WorldWideScience

Sample records for cascade v-11 pond

  1. Unintended consequences of management actions in salt pond restoration: cascading effects in trophic interactions.

    Directory of Open Access Journals (Sweden)

    John Y Takekawa

    Full Text Available Salt evaporation ponds have played an important role as habitat for migratory waterbirds across the world, however, efforts to restore and manage these habitats to maximize their conservation value has proven to be challenging. For example, salinity reduction has been a goal for restoring and managing former salt evaporation ponds to support waterbirds in the South Bay Salt Pond Restoration Project in San Francisco Bay, California, USA. Here, we describe a case study of unexpected consequences of a low-dissolved oxygen (DO event on trophic interactions in a salt pond system following management actions to reduce salinity concentrations. We document the ramifications of an anoxic event in water quality including salinity, DO, and temperature, and in the response of the biota including prey fish biomass, numerical response by California Gulls (Larus californicus, and chick survival of Forster's Tern (Sterna forsteri. Management actions intended to protect receiving waters resulted in decreased DO concentrations that collapsed to zero for ≥ 4 consecutive days, resulting in an extensive fish kill. DO depletion likely resulted from an algal bloom that arose following transition of the pond system from high to low salinity as respiration and decomposition outpaced photosynthetic production. We measured a ≥ 6-fold increase in biomass of fish dropped on the levee by foraging avian predators compared with weeks prior to and following the low-DO event. California Gulls rapidly responded to the availability of aerobically-stressed and vulnerable fish and increased in abundance by two orders of magnitude. Mark-recapture analysis of 254 Forster's Tern chicks indicated that their survival declined substantially following the increase in gull abundance. Thus, management actions to reduce salinity concentrations resulted in cascading effects in trophic interactions that serves as a cautionary tale illustrating the importance of understanding the interaction

  2. Evaluation of design factors for a cascade aerator to enhance the efficiency of an oxidation pond for ferruginous mine drainage.

    Science.gov (United States)

    Oh, Chamteut; Ji, Sangwoo; Cheong, Youngwook; Yim, Giljae; Hong, Ji-Hye

    2016-10-01

    This research focused on the optimum design of a cascade aerator to enhance the efficiency of an oxidation pond in a passive treatment system for remediating ferruginous mine drainage. For this purpose, various aeration experiments with aerators of different drop heights (0-4 m) and formations (types A and B) were executed on mine drainage. Type A simply drops the mine drainage into the oxidation pond while type B sprays the mine drainage and retains it for 8 min in each step. The efficiency enhancement of the oxidation pond was strongly dependent on the increase in pH and DO of the mine drainage discharged into the pond. The water quality improved with the increase in drop height but especially showed better effect with type B. The reasons for this result were attributed to the increase of contact surface and retention time of the mine drainage. The cascade aerator, therefore, should be designed to be as high as possible with the assistance of spraying form and retention time of the mine drainage to maximize the efficiency of the oxidation pond. These effects could be evaluated by calculating required areas of the oxidation pond for 95% of Fe(2+) oxidation. PMID:26936197

  3. EFFECT OF TROUT PRODUCTION IN CONCRETE PONDS WITH A CASCADING FLOW OF WATER ON PHYSICAL AND CHEMICAL PROPERTY OF WATER

    Directory of Open Access Journals (Sweden)

    Marcin Sidoruk

    2014-10-01

    Full Text Available Fish rearing causes changes in water quality due to the use of feed, mineral and organic fertilizers, pharmaceuticals and disinfectants. Rational fishery management aims to maintain or restore the quality of water in natural ecosystems. Cultures produce a certain amount of waste and pollutants released into the environment with waters departing from ponds, but their harmfulness depends on the conditions and type of farming. Studies on the assessment of the effects of rearing trout on physical and chemical properties of surface water were carried out in 2010-2012. Were chosen trout farm located in the Pomeranian province about 36 miles southeast of Słupsk. Water samples for physical and chemical analysis were collected every two months (a total of 12 sets samples collected and labeled them: temperature [°C], dissolved oxygen [mg · dm-3], oxygen saturation [%] electrolytic conductivity [S · cm-1], pH, redox potential [mV] and BOD5 and CODCr. The study showed that the water used to supply breeding facilities meet the requirements to be met which are inland water salmonid habitat. Only periodically for BOD5 standards have been slightly exceeded. After passing through the joints deterioration of water quality did not cause a change in the quality of the class, if only temporarily BOD5 ratio were lower in its quality from the first to the third class.

  4. WhatsUp Gold v11 Premium

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    如今,许多中小型公司都将Email和数据库等主要商务程序作为其业务运行必不可少的工具。这些程序一旦发生故障,将严重影响用户的工作,并对公司带来经济损失。因此,为了避免这些问题,需要对程序进行管理,在故障出现之前及时做出通知。WhatsUp Gold v11 Premium就是专为中小型公司推出的一个程序和网络管理方案,能够确保重要业务正常运行,令用户可以放心工作。虽然中小型公司的网络结构也同大型公司一样愈加复杂,但是必须根据它们的自身条件设计专门的网络管理方案。

  5. 216-B-3 expansion ponds closure plan

    International Nuclear Information System (INIS)

    This document describes the activities for clean closure under the Resource Conservation and Recovery Act of 1976 (RCRA) of the 216-B-3 Expansion Ponds. The 216-B-3 Expansion Ponds are operated by the US Department of Energy, Richland Operations Office (DOE-RL) and co-operated by Westinghouse Hanford Company (Westinghouse Hanford). The 216-B-3 Expansion Ponds consists of a series of three earthen, unlined, interconnected ponds that receive waste water from various 200 East Area operating facilities. The 3A, 3B, and 3C ponds are referred to as Expansion Ponds because they expanded the capability of the B Pond System. Waste water (primarily cooling water, steam condensate, and sanitary water) from various 200 East Area facilities is discharged to the Bypass pipe (Project X-009). Water discharged to the Bypass pipe flows directly into the 216-B-3C Pond. The ponds were operated in a cascade mode, where the Main Pond overflowed into the 3A Pond and the 3A Pond overflowed into the 3C Pond. The 3B Pond has not received waste water since May 1985; however, when in operation, the 3B Pond received overflow from the 3A Pond. In the past, waste water discharges to the Expansion Ponds had the potential to have contained mixed waste (radioactive waste and dangerous waste). The radioactive portion of mixed waste has been interpreted by the US Department of Energy (DOE) to be regulated under the Atomic Energy Act of 1954; the dangerous waste portion of mixed waste is regulated under RCRA

  6. 216-B-3 expansion ponds closure plan

    Energy Technology Data Exchange (ETDEWEB)

    1994-10-01

    This document describes the activities for clean closure under the Resource Conservation and Recovery Act of 1976 (RCRA) of the 216-B-3 Expansion Ponds. The 216-B-3 Expansion Ponds are operated by the US Department of Energy, Richland Operations Office (DOE-RL) and co-operated by Westinghouse Hanford Company (Westinghouse Hanford). The 216-B-3 Expansion Ponds consists of a series of three earthen, unlined, interconnected ponds that receive waste water from various 200 East Area operating facilities. The 3A, 3B, and 3C ponds are referred to as Expansion Ponds because they expanded the capability of the B Pond System. Waste water (primarily cooling water, steam condensate, and sanitary water) from various 200 East Area facilities is discharged to the Bypass pipe (Project X-009). Water discharged to the Bypass pipe flows directly into the 216-B-3C Pond. The ponds were operated in a cascade mode, where the Main Pond overflowed into the 3A Pond and the 3A Pond overflowed into the 3C Pond. The 3B Pond has not received waste water since May 1985; however, when in operation, the 3B Pond received overflow from the 3A Pond. In the past, waste water discharges to the Expansion Ponds had the potential to have contained mixed waste (radioactive waste and dangerous waste). The radioactive portion of mixed waste has been interpreted by the US Department of Energy (DOE) to be regulated under the Atomic Energy Act of 1954; the dangerous waste portion of mixed waste is regulated under RCRA.

  7. Frozen ponds

    DEFF Research Database (Denmark)

    Langer, M; Westermann, S.; Anthony, K. Walter; Wischnewski, K.; Boike, J.

    2015-01-01

    Lakes and ponds play a key role in the carbon cycle of permafrost ecosystems, where they are considered to be hotspots of carbon dioxide CO2 and methane CH4 emission. The strength of these emissions is, however, controlled by a variety of physical and biogeochemical processes whose responses to a...... warming climate are complex and only poorly understood. Small waterbodies have been attracting an increasing amount of attention since recent studies demonstrated that ponds can make a significant contribution to the CO2 and CH4emissions of tundra ecosystems. Waterbodies also have a marked effect on the...... thermal state of the surrounding permafrost; during the freezing period they prolong the period of time during which thawed soil material is available for microbial decomposition.  This study presents net CH4 production rates during the freezing period from ponds within a typical lowland tundra landscape...

  8. Design concept of Hydro cascade control system

    International Nuclear Information System (INIS)

    In this paper a design concept of the comple hydro cascade scheme is presented with the design parameters of the main technical features. The cascade control system architecture is designed considering up-to-date communication and information technology. The control algorithm is based on Pond Level Control and Economic Load Allocation concepts.

  9. Technical manual for calculating cooling pond performance

    International Nuclear Information System (INIS)

    This manual is produced in response to a growing number of requests for a technical aid to explain methods for simulating cooling pond performance. As such, it is a compilation of reports, charts and graphs developed through the years for use in analyzing situations. Section II contains a report summarizing the factors affecting cooling pond performance and lists statistical parameters used in developing performance simulations. Section III contains the graphs of simulated cooling pond performance on an hourly basis for various combinations of criteria (wind, solar, depth, air temperature and humidity) developed from the report in Section II. Section IV contains correspondence describing how to develop further data from the graphs in Section III, as well as mathematical models for the system of performance calculation. Section V contains the formulas used to simulate cooling pond performances in a cascade arrangement, such as the Fermilab Main Ring ponds. Section VI contains the calculations currently in use to evaluate the Main Ring pond performance based on current flows and Watts loadings. Section VII contains the overall site drawing of the Main Ring cooling ponds with thermal analysis and physical data

  10. Solar pond technology

    OpenAIRE

    J. Srinivasan

    1993-01-01

    Solar pond technology has made substantial progress in the last fifteen years. This paper reviews the basic principles of solar ponds and the problems encountered in their operation and maintenance. The factors which influence the technical and economic viability of solar ponds for thermal applications and power generation have been discussed.

  11. Kinescan/IBV v11: Valoración biomecánica en tiempo real

    OpenAIRE

    MONTERO VILELA, JOSE; Parra Gonzalez, Francisco; Parrilla Bernabé, Eduardo; Medina Ripoll, Enrique; Lopez Pascual, Juan; Moreno Cano, Rafael; Castelli, Andrea; Bermejo Bosch, Ignacio

    2013-01-01

    [EN] Experts in biomechanical assessment are very interested in increasing precision of the measurements, reducing the needed time for evaluating patients and giving more flexibility to their labs. Therefore, we developed a new version of our system for kinematic analysis of human movement: Kinescan/IBV V11. Kinescan/IBV V11 is based in digital video technology and is able to make a distributed pre-processing. So it can analyse automatically movements in...

  12. Par Pond water balance

    International Nuclear Information System (INIS)

    A water budget for the Par Pond hydrologic system was established in order to estimate the rate of groundwater influx to Par Pond. This estimate will be used in modeling exercises to predict Par Pond reservoir elevation and spillway discharge in the scenario where Savannah River water is no longer pumped and discharged into Par Pond. The principal of conservation of mass was used to develop the water budget, where water inflow was set equal to water outflow. Components of the water budget were identified, and the flux associated with each was determined. The water budget was considered balanced when inflow and outflow summed to zero. The results of this study suggest that Par Pond gains water from the groundwater system in the upper reaches of the reservoir, but looses water to the groundwater system near the dam. The rate of flux of groundwater from the water table aquifer into Par Pond was determined to be 13 cfs. The rate of flux from Par Pond to the water table aquifer near the dam was determined to be 7 cfs

  13. Learning Cascading

    CERN Document Server

    Covert, Michael

    2015-01-01

    This book is intended for software developers, system architects and analysts, big data project managers, and data scientists who wish to deploy big data solutions using the Cascading framework. You must have a basic understanding of the big data paradigm and should be familiar with Java development techniques.

  14. Kealia Pond - Ungulate Exclusion Fence

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This project will contribute to the building of a fence around the Kealia Pond National Wildlife Refuge. Kealia Pond NWR is home to two endangered waterbird...

  15. Expenditure Cascades

    OpenAIRE

    2014-01-01

    Prevailing economic models of consumer behavior completely ignore the well-documented link between context and evaluation. We propose and test a theory that explicitly incorporates this link. Changes in one group's spending shift the frame of reference that defines consumption standards for others just below them on the income scale, giving rise to expenditure cascades. Our model, a descendant of James Duesenberry's relative income hypothesis, predicts the observed ways in which individual sa...

  16. Agricultural ponds support amphibian populations

    Science.gov (United States)

    Knutson, M.G.; Richardson, W.B.; Reineke, D.M.; Gray, B.R.; Parmelee, J.R.; Weick, S.E.

    2004-01-01

    In some agricultural regions, natural wetlands are scarce, and constructed agricultural ponds may represent important alternative breeding habitats for amphibians. Properly managed, these agricultural ponds may effectively increase the total amount of breeding habitat and help to sustain populations. We studied small, constructed agricultural ponds in southeastern Minnesota to assess their value as amphibian breeding sites. Our study examined habitat factors associated with amphibian reproduction at two spatial scales: the pond and the landscape surrounding the pond. We found that small agricultural ponds in southeastern Minnesota provided breeding habitat for at least 10 species of amphibians. Species richness and multispecies reproductive success were more closely associated with characteristics of the pond (water quality, vegetation, and predators) compared with characteristics of the surrounding landscape, but individual species were associated with both pond and landscape variables. Ponds surrounded by row crops had similar species richness and reproductive success compared with natural wetlands and ponds surrounded by nongrazed pasture. Ponds used for watering livestock had elevated concentrations of phosphorus, higher turbidity, and a trend toward reduced amphibian reproductive success. Species richness was highest in small ponds, ponds with lower total nitrogen concentrations, tiger salamanders (Ambystoma tigrinum) present, and lacking fish. Multispecies reproductive success was best in ponds with lower total nitrogen concentrations, less emergent vegetation, and lacking fish. Habitat factors associated with higher reproductive success varied among individual species. We conclude that small, constructed farm ponds, properly managed, may help sustain amphibian populations in landscapes where natural wetland habitat is rare. We recommend management actions such as limiting livestock access to the pond to improve water quality, reducing nitrogen input, and

  17. The identification of a cascade hypernucleus

    CERN Document Server

    Mondal, A S; Husain, A; Kasim, M M

    1979-01-01

    In a systematic search for rare hypernuclear species in nuclear emulsion exposed to 3.0 GeV/c K/sup -/-mesons at the CERN PS, an event with three connecting stars has been observed. The two secondary stars are most probably due to the decay of a cascade hypernucleus according to the following channel: /sub Xi //sup -13/-C to /sub Lambda //sup 8 /Be+/sub Lambda //sup 5/He+Q. The binding energy of the Xi - hypernucleus is B/sub Xi /-(/sub Xi //sup 13/-C)=(18.1+or-3.2) MeV. (11 refs).

  18. Microbiology of solar salt ponds

    Science.gov (United States)

    Javor, B.

    1985-01-01

    Solar salt ponds are shallow ponds of brines that range in salinity from that of normal seawater (3.4 percent) through NaCl saturation. Some salterns evaporate brines to the potash stage of concentration (bitterns). All the brines (except the bitterns, which are devoid of life) harbor high concentrations of microorganisms. The high concentrations of microorganisms and their adaptation to life in the salt pond are discussed.

  19. Pond Ecology in the Classroom.

    Science.gov (United States)

    Kneidl, Sally Stenhouse

    1993-01-01

    Describes activities with organisms from freshwater ponds and ditches. Several experiments involve predation, some involve habitat choices, and one addressees the role of sunlight in supporting plant-eating animals. (PR)

  20. Do Cascades Recur?

    OpenAIRE

    Cheng, Justin; Adamic, Lada A.; Kleinberg, Jon; Leskovec, Jure

    2016-01-01

    Cascades of information-sharing are a primary mechanism by which content reaches its audience on social media, and an active line of research has studied how such cascades, which form as content is reshared from person to person, develop and subside. In this paper, we perform a large-scale analysis of cascades on Facebook over significantly longer time scales, and find that a more complex picture emerges, in which many large cascades recur, exhibiting multiple bursts of popularity with period...

  1. Par Pond vegetation status 1996

    International Nuclear Information System (INIS)

    The water level of Par Pond was lowered approximately 20 feet in mid-1991 in order to protect downstream residents from possible dam failure suggested by subsidence on the downstream slope of the dam and to repair the dam. This lowering exposed both emergent and nonemergent macrophyte beds to drying conditions resulting in extensive losses. A survey of the newly emergent, shoreline aquatic plant communities of Par Pond began in June 1995, three months after the refilling of Par Pond to approximately 200 feet above mean sea level. These surveys continued in July, September, and late October, 1995, and into the early spring and late summer of 1996. Communities similar to the pre-drawdown, Par Pond aquatic plant communities continue to become re-established. Emergent beds of maidencane, lotus, waterlily, watershield, and Pontederia are extensive and well developed. Measures of percent cover, width of beds, and estimates of area of coverage with satellite data indicate regrowth within two years of from 40 to 60% of levels prior to the draw down. Cattail occurrence continued to increase during the summer of 1996, especially in the former warm arm of Par Pond, but large beds common to Par Pond prior to the draw down still have not formed. Lotus has invaded and occupies many of the areas formerly dominated by cattail beds. To track the continued development of macrophytes in Par Pond, future surveys through the summer and early fall of 1997, along with the evaluation of satellite data to map the extent of the macrophyte beds of Par Pond, are planned

  2. 2101-M pond closure plan

    International Nuclear Information System (INIS)

    This document describes activities for the closure of a surface impoundment (2101-M Pond) at the Hanford Site. The 2101-H Pond was initially constructed in 1953 to serve as a drainage collection area for the 2101-H Building. (Until the Basalt Waste Isolation Project (BWIP) Laboratory was constructed in the 2101-M Building in 1979--1981, the only source contributing discharge to the pond was condensate water from the 2101-H Building heating, ventilation, and air conditioning (HVAC) system. The drains for the BWIP Laboratory rooms were plumbed into a 4-in., cast-iron, low-pressure drain pipe that carries waste water from the HVAC system to the pond. During the active life of the BWIP Laboratory, solutions of dissolved barium in groundwater samples were discharged to the 2101-M Pond via the laboratory drains. As a result of the discharges, a Part A permit application was initially submitted to the Washington State Department of Ecology (Ecology) in August 1986 which designates the 2101-M Pond as a surface impoundment

  3. Theoretical line ratios for high temperature and high density Ne V11 plasmas

    International Nuclear Information System (INIS)

    Relative ionic populations and line intensity ratios have been calculated for the ten n=2 levels of Ne VII over a range of electron densities, 1012-1017 cm-3 and temperatures, 5 x 105 - 4 x 106 K, suitable for comparison with laboratory experiments. Electron excitation rates were calculated using the R-matrix method, with the effect of proton and electron collisions between the fine structure triplet levels being considered. A test calculation including the effects of cascading from the n=3 levels indicated that although the processes were not important at high densities, the predicted ratios changed by up to 40% at the lowest density considered. A brief comparison is also made with experimental results. (author)

  4. Blogging from North Pond

    Science.gov (United States)

    Marziali, C. G.; Edwards, K. J.

    2009-12-01

    Sea going research expeditions provide an ideal opportunity for outreach through blogs: the finite duration limits the author's commitment; scientists are usually in a remote location with fewer distractions; and fieldwork is visual and interesting to describe. Over four weeks this winter, Katrina Edwards of USC authored a blog about her deep-sea drilling expedition to North Pond, a depression in the ocean crust in the mid-Atlantic. She emailed daily dispatches and photos to USC Media Relations, which maintained a (still accessible) blog. Written for the general public, the blog quickly attracted interest from lay readers as well as from media organizations. Scientific American carried the blog on its web site, and the National Science Foundation linked to it in its "Science 360" electronic news digest. The blog also led to a Q&A with Edwards in the widely-read "Behind the Scenes" feature of LiveScience. Interest from science bloggers and National Geographic towards the end suggests that the blog could have expanded its reach given more time: expeditions lasting between six weeks and three months, such as occur during ocean drilling expeditions, would appear to be ideal candidates for a blog. Most importantly, the blog educated readers about the importance to planetary life of what Edwards calls the "intraterrestrials": the countless microbes that inhabit the oceanic crust and influence major chemical and biological cycles. Considering that the subjects of the expedition were invisible critters in a pitch-dark place, the blog shows what can be accomplished by scientists and institutions committed to public outreach.

  5. Solar Pond Fluid Dynamics and Heat Transfer

    Science.gov (United States)

    Jones, G. F.

    1984-01-01

    The primary objective of the solar pond research was to obtain an indepth understanding of solar pond fluid dynamics and heat transfer. The key product was the development of a validated one-dimensional computer model with the capability to accurately predict time-dependent solar pond temperature, salinities, and interface motions. Laboratory scale flow visualization experiments were conducted to better understand layer motion. Two laboratory small-scale ponds and a large-scale outdoor solar pond were designed and built to provide quantitative data. This data provided a basis for validating the model and enhancing the understanding of pond dynamic behavior.

  6. Pond 1 : closure of the first oil sands tailings pond

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, H.B.; Wells, P.S.; Cox, L [Suncor Energy, Fort McMurray, AB (Canada)

    2010-10-01

    This article discussed the closure and reclamation of the first oilsands tailings pond in the Athabasca Oil Sands region. Pond 1 began construction in 1966, received tailings until 1995, and was released for reclamation in 2007. Infilling was completed in 2009, and surface land forming and revegetation were finished in the fall of 2010. The challenges associated with closing a tailings pond were unknown. Environmental goals evolved over the life of the pond, from initial absence to grass cover to prevent wind erosion, tree plantings for wildlife habitat, and finally to reclamation to viable ecosystems compatible with pre-development. The final stage involved infilling and reclamation of the pond interior. The Mature Fine Tailings were removed to a different location for storage and treatment. Infilling with course tailings sand established a trafficable surface on which to perform reclamation activities. The landform design involved a sand pile that had become bird habitat; a small marsh wetland; swales to collect and control surface runoff water; and hummocks for topographical diversity and increased biodiversity. The reclamation soil cover was a peat/mineral mix. Micro-topographical enhancements created locally diverse conditions for wildlife habitat. An excavated area was lined with a geosynthetic material for water retention, amended with peat/mineral mix, and planted with wetland species to create the marsh. The revegetation involved 33 different species of trees, shrubs, grasses, and aquatic plants. The pond closure is taking place in a highly regulated environment with a substantial knowledge base of reclamation techniques and clearly defined reclamation goals. 8 figs.

  7. 100-D Ponds closure plan

    International Nuclear Information System (INIS)

    The 100-D Ponds is located within the Hanford Site and is a land surface impoundment for the disposal of liquid effluent. This unit has been classified as a Resource Conservation and Recovery Act of 1976 (RCRA) treatment, storage, and/or disposal (TSD) unit because of a potential for having received nonradioactive, regulated dangerous waste. These ponds are no longer being used to receive waste with a potential to be dangerous and so will be closed as a RCRA-regulated TSD unit consists of a Part A Permit Application (Revision 3) and a closure plan. The Part A Permit Application revisions are explained at the beginning of the Part A section. The closure plan presents a description of the 100-D Ponds structures and boundaries, the history of the waste managed, and the approach that will be followed to close the 100-0 Ponds TSD unit. Radionuclides (source, special nuclear, and by-product material) are not within the scope of WAC 173-303 or of this closure plan. The dangerous waste directly leading to the classification of the site as a RCRA TSD unit did not contain radioactive constituents. Information provided on radionuclides is only for general knowledge where appropriate. Only dangerous constituents derived from the 100-D Ponds operations are addressed in this closure plan

  8. Invertebrate communities of the High Arctic ponds in Hornsund

    Directory of Open Access Journals (Sweden)

    Luoto Tomi P.

    2016-03-01

    Full Text Available How environmental conditions influence current distributions of organisms at the local scale in sensitive High Arctic freshwaters is essential to understand in order to better comprehend the cascading consequences of the ongoing climate change. This knowledge is also important background data for paleolimnological assessments of long-term limnoecological changes and in describing the range of environmental variability. We sampled five limnologically different freshwater sites from the Fuglebergsletta marine terrace in Hornsund, southern Svalbard, for aquatic invertebrates. Invertebrate communities were tested against non-climatic environmental drivers as limnological and catchment variables. A clear separation in the communities between the sites was observed. The largest and deepest lake was characterized by a diverse Chironomidae community but Cladocera were absent. In a pond with marine influence, crustaceans, such as Ostracoda, Amphipoda, and calanoid Copepoda were the most abundant invertebrates. Two nutrient-rich ponds were dominated by a chironomid, Orthocladius consobrinus, whereas themost eutrophic pond was dominated by the cladoceran Daphnia pulex, suggesting decreasing diversity along with the trophic status. Overall, nutrient related variables appeared to have an important influence on the invertebrate community composition and diversity, the trophic state of the sites being linked with their exposure to geese guano. Other segregating variables included water color, presence/absence of fish, abundance of aquatic vegetation and lake depth. These results suggest that since most of these variables are climate-driven at a larger scale, the impacts of the ongoing climate change will have cumulative effects on aquatic ecosystems.

  9. Bosonic Cascade Laser

    OpenAIRE

    Liew, T. C. H.; Glazov, M. M.; Kavokin, K. V.; Shelykh, I. A.; Kaliteevski, M A; Kavokin, A.V.

    2012-01-01

    We propose a concept of a quantum cascade laser based on transitions of bosonic quasiparticles (excitons and exciton-polaritons) in a parabolic potential trap in a semiconductor microcavity. This laser would emit terahertz radiation due to bosonic stimulation of excitonic transitions. Dynamics of a bosonic cascade is strongly different from the dynamics of a conventional fermionic cascade laser. We show that populations of excitonic ladders are parity-dependent and quantized if the laser oper...

  10. Comment on "Comparison of dose rates calculated on Nucletron NPS v11 catheter tracking versus catheter describing"

    CERN Document Server

    Van der Laarse, R

    2003-01-01

    N D MacDougall has reported to Nucletron a dose error in the module MPS v11.33 of the Nucletron NPS brachytherapy program. This dose error occurred when an implant was reconstructed using the image tracking method. MPS v11 offers five methods for reconstruction from radiographs of the 3D localization in space of an iridium wire implant. The method using catheter-describing points is the most accurate one. It is based on digitizing the corresponding images of X-ray markers in the catheters on two radiographs, taken at different angles with an isocentric X-ray machine such as a treatment simulator. The method using tracking is the least accurate one. It tracks wire images on the radiographs to reconstruct a wire in space consisting of maximally 98 wire segments. This is the least accurate method because there is no correspondence between the image points of a wire on the radiographs.

  11. Par Pond Fish, Water, and Sediment Chemistry

    International Nuclear Information System (INIS)

    The objectives of this report are to describe the Par Pond fish community and the impact of the drawdown and refill on the community, describe contaminant levels in Par Pond fish, sediments, and water and indicate how contaminant concentrations and distributions were affected by the drawdown and refill, and predict possible effects of future water level fluctuations in Par Pond

  12. How Healthy Is Our Pond?

    Science.gov (United States)

    Sterling, Donna R.; Hargrove, Dori L.

    2014-01-01

    With crosscutting concepts such as stability and change in the "Next Generation Science Standards," this article was written for those who have wondered how to teach these concepts in a way that is relevant to students. In this investigation, students ask the question, "Why is the pond dirty?" As students investigate the health…

  13. Cascade quantum teleportation

    Institute of Scientific and Technical Information of China (English)

    ZHOU Nan-run; GONG Li-hua; LIU Ye

    2006-01-01

    In this letter a cascade quantum teleportation scheme is proposed. The proposed scheme needs less local quantum operations than those of quantum multi-teleportation. A quantum teleportation scheme based on entanglement swapping is presented and compared with the cascade quantum teleportation scheme. Those two schemes can effectively teleport quantum information and extend the distance of quantum communication.

  14. Collision cascade temperature

    International Nuclear Information System (INIS)

    Interaction of a projectile with a solid has been considered in detail. It has been found that any collision cascade generated by a projectile can be characterized by the average kinetic energy of cascade atoms that represents an 'instantaneous temperature' of the cascade during its very short lifetime (10-12 s). We refer to this value as the 'dynamic temperature' in order to emphasize the fact that cascade atoms are in a dynamic equilibrium and have a definite energy distribution. The dynamic temperature defines the electron distribution in the cascade area and, hence, the ionization probability of sputtered atoms. The energy distribution of cascade atoms and, as a consequence, the dynamic temperature can be found experimentally by measuring the energy distribution of sputtered atoms. The calculated dynamic temperature has been found to be in good agreement with the experimental data on ion formation in the case of cesium and oxygen ion sputtering of silicon. Based on the developed model we suggest an experimental technique for a radical improvement of the existing cascade sputtering models

  15. Effects of pond draining on biodiversity and water quality of farm ponds.

    Science.gov (United States)

    Usio, Nisikawa; Imada, Miho; Nakagawa, Megumi; Akasaka, Munemitsu; Takamura, Noriko

    2013-12-01

    Farm ponds have high conservation value because they contribute significantly to regional biodiversity and ecosystem services. In Japan pond draining is a traditional management method that is widely believed to improve water quality and eradicate invasive fish. In addition, fishing by means of pond draining has significant cultural value for local people, serving as a social event. However, there is a widespread belief that pond draining reduces freshwater biodiversity through the extirpation of aquatic animals, but scientific evaluation of the effectiveness of pond draining is lacking. We conducted a large-scale field study to evaluate the effects of pond draining on invasive animal control, water quality, and aquatic biodiversity relative to different pond-management practices, pond physicochemistry, and surrounding land use. The results of boosted regression-tree models and analyses of similarity showed that pond draining had little effect on invasive fish control, water quality, or aquatic biodiversity. Draining even facilitated the colonization of farm ponds by invasive red swamp crayfish (Procambarus clarkii), which in turn may have detrimental effects on the biodiversity and water quality of farm ponds. Our results highlight the need for reconsidering current pond management and developing management plans with respect to multifunctionality of such ponds. Efectos del Drenado de Estanques sobre la Biodiversidad y la Calidad del Agua en Estanques de Cultivo. PMID:23869702

  16. Informational Cascades : A Mirage?

    OpenAIRE

    Spiwoks, Markus; Bizer, Kilian; Hein, Oliver

    2008-01-01

    Experimental research found contradictory results regarding the occurrence of informational cascades. Whereas Anderson and Holt (1997) confirmed the model of Banerjee (1992), and Bikhchandani et al. (1992) through lab tests, Huck and Oechssler (2000) came to contradictory results on crucial issues. This article presents experimental evidence supporting further doubts concerning "Bayesian" informational cascades: Just under two thirds of all decisions are characterized by an excessive orientat...

  17. Cascade Lake: A Novel

    OpenAIRE

    Pack, Camille Marian

    2009-01-01

    Twenty-two-year-old Macy Oman narrates the book in retrospect from Cascade, Oregon, where she is visiting her mother. Macy's father moved with her to Portland shortly after the accidental death of her brother, Nick, seven years before the narration begins. Macy's mother stayed behind in Cascade. Thematically the work centers on the emotional repercussions of these losses. Macy's, and her older lover Jason's, involvement with Nick's death is unknown to everyone. Her guilt and her mother's perc...

  18. Pond Fish Culture Practices in Nigeria

    OpenAIRE

    J.A. Akankali; J.F.N. Abowei; A. Eli

    2011-01-01

    Pond fish culture practices in Nigeria was reviewed to refresh the minds of fish and other interested stake holders on some basic principles involved in pond fish culture. Fish pond system is the commonest agricultural techniques in the Niger Delta Region of Nigeria. Profit making, job creation, provision of raw materials for several industries and increase in foreign exchange earnings are some benefits. However, loss of land and introduction some water borne diseases are some disadvantages i...

  19. Review of SERI Solar Pond Work

    Science.gov (United States)

    Zangrando, F.; Johnson, D. H.

    1984-01-01

    Development of models of pond thermal performance; analysis of solar pond use for building space heat and hot water production; use of low-temperature pond-produced heat for industrial processes, desalination, and electricity production; development of direct-contact heat exchanger to reduce conversion equipment cost; determination of effects of extracted heat and mass from the storage layer on pond performance; and investigation of factors which determine gradient layer stability and the stability of this interface between this level and the upper and lower convecting layers were described.

  20. Mercury assessment of Brandy Pond T39 MD, Maine

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Brandy Pond is a remote, shallow, pond in east‐central Maine. A bald eagle (Haliaeetus leucocephalus) nest territory has existed on the pond since the mid-1960s....

  1. The Lower Vistula Cascade

    Directory of Open Access Journals (Sweden)

    Ireneusz Ankiersztejn

    2013-09-01

    Full Text Available This article outlines the development and modifications of the Lower Vistula Cascade concept in order to meet changing requirements for utilisation of the river for power generation and navigation purposes. In the years 1957–1993 the Lower Vistula Cascade concept was modified in order to achieve the maximum power generation capacity (an example was the high efficiency of the hydropower station at the Włocławek Barrage, built in 1970 as the first and so far the only barrage of the proposed cascade. In the 1990s the potential economic benefits of the Vistula River management were re-evaluated in favour of natural and landscape merits, and another multi-variant modification of the Lower Vistula Cascade concept was carried out applying the principles of sustainable development and environmental protection. The analysis of the cascade variants considered in 1999 led to the conclusion that there is no justification for the project implementation, with the exception of the barrage located downstream of Włocławek (Nieszawa-Ciechocinek, the construction of which is essential for the Włocławek Barrage safety.

  2. Cascade Organic Solar Cells

    KAUST Repository

    Schlenker, Cody W.

    2011-09-27

    We demonstrate planar organic solar cells consisting of a series of complementary donor materials with cascading exciton energies, incorporated in the following structure: glass/indium-tin-oxide/donor cascade/C 60/bathocuproine/Al. Using a tetracene layer grown in a descending energy cascade on 5,6-diphenyl-tetracene and capped with 5,6,11,12-tetraphenyl- tetracene, where the accessibility of the π-system in each material is expected to influence the rate of parasitic carrier leakage and charge recombination at the donor/acceptor interface, we observe an increase in open circuit voltage (Voc) of approximately 40% (corresponding to a change of +200 mV) compared to that of a single tetracene donor. Little change is observed in other parameters such as fill factor and short circuit current density (FF = 0.50 ± 0.02 and Jsc = 2.55 ± 0.23 mA/cm2) compared to those of the control tetracene-C60 solar cells (FF = 0.54 ± 0.02 and Jsc = 2.86 ± 0.23 mA/cm2). We demonstrate that this cascade architecture is effective in reducing losses due to polaron pair recombination at donor-acceptor interfaces, while enhancing spectral coverage, resulting in a substantial increase in the power conversion efficiency for cascade organic photovoltaic cells compared to tetracene and pentacene based devices with a single donor layer. © 2011 American Chemical Society.

  3. Evaluation of the range shifter model for proton pencil-beam scanning for the Eclipse v.11 treatment planning system.

    Science.gov (United States)

    Matysiak, Witold; Yeung, Daniel; Slopsema, Roelf; Li, Zuofeng

    2016-01-01

    Existing proton therapy pencil-beam scanning (PBS) systems have limitations on the minimum range to which a patient can be treated. This limitation arises from practical considerations, such as beam current intensity, layer spacing, and delivery time. The range shifter (RS) - a slab of stopping material inserted between the nozzle and the patient - is used to reduce the residual range of the incident beam so that the treatment ranges can be extended to shallow depths. Accurate modeling of the RS allows one to calculate the beam spot size entering the patient, given the proton energy, for arbitrary positions and thicknesses of the RS in the beam path. The Eclipse version 11 (v11) treatment planning system (TPS) models RS-induced beam widening by incorporating the scattering properties of the RS material into the V-parameter. Monte Carlo simulations with Geant4 code and analytical calculations using the Fermi-Eyges (FE) theory with Highland approximation of multiple Coulomb scattering (MCS) were employed to calculate proton beam widening due to scattering in the RS. We demonstrated that both methods achieved consistent results and could be used as a benchmark for evaluating the Eclipse V-parameter model. In most cases, the V-parameter model correctly predicted the beam spot size after traversing the RS. However, Eclipse did not enforce the constraint for a nonnegative covariance matrix when fitting the spot sizes to derive the phase space parameters, which resulted in incorrect calculations under specific conditions. In addition, Eclipse v11 incorrectly imposed limits on the individual values of the phase space parameters, which could lead to incorrect spot size values in the air calculated for beams with spot sigmas <3.8 mm. Notably, the TPS supplier (Varian) and hardware vendor (Ion Beam Applications) inconsistently refer to the RS position, which may result in improper spot size calculations. PMID:27074461

  4. Zooplankton succession in fingerling production ponds

    Science.gov (United States)

    Many pond cultured species require a range of zooplankton species for consumption before they can be weaned onto manufactured feed. The widest variety of plankton species develops when empty ponds are filled and fertilized. Use of organic and inorganic fertilizers facilitates the development of ba...

  5. Assessment of Ash Pond Project effectiveness

    International Nuclear Information System (INIS)

    In April 1989 the US Department of Energy (DOE) completed the Ash Pond Isolation Project at the Weldon Spring Site Remedial Action Project (WSSRAP). This Interim Response Action (IRA) was designed to reduce uranium concentrations in surface water released from the Ash Pond Outfall at the Weldon Spring Site (WSS). Uranium concentrations at this outfall have been measured as high as 5,500 pCi/l with an average concentration of 1,498 pCi/l. This project was one of several IRAs aimed at improving health and safety conditions at the WSS prior to the Record of Decision. The Ash Pond Isolation Project was constructed to intercept surface water runoff to the Ash Pond drainage and redirect flows around the Ash Pond and South Dump areas, thereby eliminating leaching and transport of uranium-contaminated materials from these source areas. The DOE has monitored the releases from the Ash Pond Outfall in fulfillment of the site's National Pollutant Discharge Elimination System Permit and initiated additional monitoring to further assess the effectiveness of the Ash Pond Isolation Project. Results of this monitoring effort indicate a reduction in uranium concentrations measured at the Ash Pond Outfall from a pre-completion average of 1,498 pCi/l to an average of 145 pCi/l following completion of the IRA. 6 refs., 6 figs., 3 tabs

  6. 33 CFR 117.600 - Lagoon Pond.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Lagoon Pond. 117.600 Section 117.600 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY BRIDGES DRAWBRIDGE OPERATION REGULATIONS Specific Requirements Massachusetts § 117.600 Lagoon Pond. The draw of the Lagoon...

  7. WMOST v2 Case Study: Monponsett Ponds

    Science.gov (United States)

    This webinar presents an overview of the preliminary results of a case study application of EPA's Watershed Management Optimization Support Tool v2 (WMOST) for stakeholders in the Monponsett Ponds Watershed Workgroup. Monponsett Ponds is a large water system consisting of two ba...

  8. Aquatic studies of Gable Mountain Pond

    International Nuclear Information System (INIS)

    Studies of the biotic and abiotic components of the Gable Mountain Pond (HAPO cooling water disposal pond) ecosystem were undertaken to determine if there was a potential problem for off-site transfer of radioactivity to man originating with the aquatic food web. Most of the 137Cs in the pond is associated with the sediments which are probably the main source of 137Cs for uptake by the biota. Generally, highest concentrations of 137Cs and other radioisotopes were found in the upper two inches of sediments in the northwest end of the pond and in the deeper areas along the long-axis of the pond. Native goldfish had maximum and average 137Cs concentrations of about 340 and 170 pCi/g dry wt, respectively. Algae, macrophytes, and detritus comprised the main food items of the goldfish, and the 137Cs levels in the plants were usually higher than the 137Cs concentration in the fish. The 137Cs concentrations of wild experimental ducks restricted to Gable Mountain Pond were approximately the same as resident coots, but significantly higher than transient wild ducks. Neither the goldfish nor the waterfowl inhabiting the pond attained concentrations of 137Cs exceeding acceptable limits. Sediment, however, could be a source of high concentrations of radioactivity or radioactive contamination concern if the concentration of radiocontaminants increased and/or the pond dries up, and the contaminated sediments become windborne. (U.S.)

  9. 100-D Ponds closure plan. Revision 1

    Energy Technology Data Exchange (ETDEWEB)

    Petersen, S.W.

    1997-09-01

    The 100-D Ponds is a Treatment, Storage, and Disposal (TSD) unit on the Hanford Facility that received both dangerous and nonregulated waste. This Closure Plan (Rev. 1) for the 100-D Ponds TSD unit consists of a RCRA Part A Dangerous Waste Permit Application (Rev. 3), a RCRA Closure Plan, and supporting information contained in the appendices to the plan. The closure plan consists of eight chapters containing facility description, process information, waste characteristics, and groundwater monitoring data. There are also chapters containing the closure strategy and performance standards. The strategy for the closure of the 100-D Ponds TSD unit is clean closure. Appendices A and B of the closure plan demonstrate that soil and groundwater beneath 100-D Ponds are below cleanup limits. All dangerous wastes or dangerous waste constituents or residues associated with the operation of the ponds have been removed, therefore, human health and the environment are protected. Discharges to the 100-D Ponds, which are located in the 100-DR-1 operable unit, were discontinued in June 1994. Contaminated sediment was removed from the ponds in August 1996. Subsequent sampling and analysis demonstrated that there is no contamination remaining in the ponds, therefore, this closure plan is a demonstration of clean closure.

  10. Par Pond vegetation status Summer 1995 -- Summary

    International Nuclear Information System (INIS)

    The water level of Par Pond was lowered approximately 20 feet in mid-1991 in order to protect downstream residents from possible dam failure suggested by subsidence on the downstream slope of the dam and to repair the dam. This lowering exposed both emergent and nonemergent macrophyte beds to drying conditions resulting in extensive losses. A survey of the newly emergent, shoreline aquatic plant communities of Par Pond began in June 1995, three months after the refilling of Par Pond to approximately 200 feet above mean sea level. These surveys continued in July, September, and late October, 1995. Communities similar to the pre-drawdown, Par Pond aquatic plant communities are becoming re-established. Emergent beds of maidencane, lotus, waterlily, and watershield are extensive and well developed. Cattail occurrence continued to increase during the summer, but large beds common to Par Pond prior to the drawdown have not formed. Estimates from SPOT HRV, remote sensing satellite data indicated that as much as 120 hectares of emergent wetlands vegetation may have been present along the Par Pond shoreline by early October, 1995. To track the continued development of macrophytes in Par Pond, future surveys throughout 1996 and 1997, along with the continued evaluation of satellite data to map the areal extent of the macrophyte beds of Par Pond, are planned

  11. 100-D Ponds closure plan. Revision 1

    International Nuclear Information System (INIS)

    The 100-D Ponds is a Treatment, Storage, and Disposal (TSD) unit on the Hanford Facility that received both dangerous and nonregulated waste. This Closure Plan (Rev. 1) for the 100-D Ponds TSD unit consists of a RCRA Part A Dangerous Waste Permit Application (Rev. 3), a RCRA Closure Plan, and supporting information contained in the appendices to the plan. The closure plan consists of eight chapters containing facility description, process information, waste characteristics, and groundwater monitoring data. There are also chapters containing the closure strategy and performance standards. The strategy for the closure of the 100-D Ponds TSD unit is clean closure. Appendices A and B of the closure plan demonstrate that soil and groundwater beneath 100-D Ponds are below cleanup limits. All dangerous wastes or dangerous waste constituents or residues associated with the operation of the ponds have been removed, therefore, human health and the environment are protected. Discharges to the 100-D Ponds, which are located in the 100-DR-1 operable unit, were discontinued in June 1994. Contaminated sediment was removed from the ponds in August 1996. Subsequent sampling and analysis demonstrated that there is no contamination remaining in the ponds, therefore, this closure plan is a demonstration of clean closure

  12. Pond of Illusion: Interacting through Mixed Reality

    DEFF Research Database (Denmark)

    Nobel-Jørgensen, Morten; Nielsen, Jannik Boll; Larsen, Anders Boesen Lindbo;

    2013-01-01

    Pond of Illusion is a mixed reality installation where a virtual space (the pond) is injected between two real spaces. The users are in either of the real spaces, and they can see each other through windows in the virtual space as illustrated in Figure 1(left). The installation attracts people to a...... large display in either of the real spaces by allowing them to feed virtual fish swimming in the pond. Figure 1(middle) shows how a Microsoft Kinect mounted on top of the display is used for detecting throw motions, which triggers virtual breadcrumbs to be thrown into the pond for feeding the nearby...... fish. Of course, the fish may not be available because they are busy eating what people have thrown into the pond from the other side....

  13. Intermediate pond sizes contain the highest density, richness, and diversity of pond-breeding amphibians.

    Directory of Open Access Journals (Sweden)

    Raymond D Semlitsch

    Full Text Available We present data on amphibian density, species richness, and diversity from a 7140-ha area consisting of 200 ponds in the Midwestern U.S. that represents most of the possible lentic aquatic breeding habitats common in this region. Our study includes all possible breeding sites with natural and anthropogenic disturbance processes that can be missing from studies where sampling intensity is low, sample area is small, or partial disturbance gradients are sampled. We tested whether pond area was a significant predictor of density, species richness, and diversity of amphibians and if values peaked at intermediate pond areas. We found that in all cases a quadratic model fit our data significantly better than a linear model. Because small ponds have a high probability of pond drying and large ponds have a high probability of fish colonization and accumulation of invertebrate predators, drying and predation may be two mechanisms driving the peak of density and diversity towards intermediate values of pond size. We also found that not all intermediate sized ponds produced many larvae; in fact, some had low amphibian density, richness, and diversity. Further analyses of the subset of ponds represented in the peak of the area distribution showed that fish, hydroperiod, invertebrate density, and canopy are additional factors that drive density, richness and diversity of ponds up or down, when extremely small or large ponds are eliminated. Our results indicate that fishless ponds at intermediate sizes are more diverse, produce more larvae, and have greater potential to recruit juveniles into adult populations of most species sampled. Further, hylid and chorus frogs are found predictably more often in ephemeral ponds whereas bullfrogs, green frogs, and cricket frogs are found most often in permanent ponds with fish. Our data increase understanding of what factors structure and maintain amphibian diversity across large landscapes.

  14. Intermediate pond sizes contain the highest density, richness, and diversity of pond-breeding amphibians.

    Science.gov (United States)

    Semlitsch, Raymond D; Peterman, William E; Anderson, Thomas L; Drake, Dana L; Ousterhout, Brittany H

    2015-01-01

    We present data on amphibian density, species richness, and diversity from a 7140-ha area consisting of 200 ponds in the Midwestern U.S. that represents most of the possible lentic aquatic breeding habitats common in this region. Our study includes all possible breeding sites with natural and anthropogenic disturbance processes that can be missing from studies where sampling intensity is low, sample area is small, or partial disturbance gradients are sampled. We tested whether pond area was a significant predictor of density, species richness, and diversity of amphibians and if values peaked at intermediate pond areas. We found that in all cases a quadratic model fit our data significantly better than a linear model. Because small ponds have a high probability of pond drying and large ponds have a high probability of fish colonization and accumulation of invertebrate predators, drying and predation may be two mechanisms driving the peak of density and diversity towards intermediate values of pond size. We also found that not all intermediate sized ponds produced many larvae; in fact, some had low amphibian density, richness, and diversity. Further analyses of the subset of ponds represented in the peak of the area distribution showed that fish, hydroperiod, invertebrate density, and canopy are additional factors that drive density, richness and diversity of ponds up or down, when extremely small or large ponds are eliminated. Our results indicate that fishless ponds at intermediate sizes are more diverse, produce more larvae, and have greater potential to recruit juveniles into adult populations of most species sampled. Further, hylid and chorus frogs are found predictably more often in ephemeral ponds whereas bullfrogs, green frogs, and cricket frogs are found most often in permanent ponds with fish. Our data increase understanding of what factors structure and maintain amphibian diversity across large landscapes. PMID:25906355

  15. CSS - Cascading Style Sheets

    OpenAIRE

    Martinelli, Massimo

    2009-01-01

    Curso "CSS - Cascading Style Sheets" sobre programación web con CSS para el "Máster doble competencia en ciencias informáticas y ciencias sociales" ("Master double competence in computer science and social science"). Proyecto TEMPUS JEP – 26235-2005

  16. Pond Fish Culture Practices in Nigeria

    Directory of Open Access Journals (Sweden)

    J.A. Akankali

    2011-06-01

    Full Text Available Pond fish culture practices in Nigeria was reviewed to refresh the minds of fish and other interested stake holders on some basic principles involved in pond fish culture. Fish pond system is the commonest agricultural techniques in the Niger Delta Region of Nigeria. Profit making, job creation, provision of raw materials for several industries and increase in foreign exchange earnings are some benefits. However, loss of land and introduction some water borne diseases are some disadvantages in pond fish culture. This articles reviews the fish pond management processes, stocking of ponds, feeding of fish, types of culture, fish farming combined with other branches of agriculture, rearing of fish for purposes other than food, other fish culture, types of fish used for fish culture in central east Africa, general biology of the species of value in fish culture and suitable combinations of fish for stocking to reawaken the minds of individuals, companies and government on the need to develop pond fish culture in Nigeria.

  17. CO₂ efflux from shrimp ponds in Indonesia.

    Directory of Open Access Journals (Sweden)

    Frida Sidik

    Full Text Available The conversion of mangrove forest to aquaculture ponds has been increasing in recent decades. One of major concerns of this habitat loss is the release of stored 'blue' carbon from mangrove soils to the atmosphere. In this study, we assessed carbon dioxide (CO₂ efflux from soil in intensive shrimp ponds in Bali, Indonesia. We measured CO₂ efflux from the floors and walls of shrimp ponds. Rates of CO₂ efflux within shrimp ponds were 4.37 kg CO₂ m⁻² y⁻¹ from the walls and 1.60 kg CO₂ m⁻² y⁻¹ from the floors. Combining our findings with published data of aquaculture land use in Indonesia, we estimated that shrimp ponds in this region result in CO₂ emissions to the atmosphere between 5.76 and 13.95 Tg y⁻¹. The results indicate that conversion of mangrove forests to aquaculture ponds contributes to greenhouse gas emissions that are comparable to peat forest conversion to other land uses in Indonesia. Higher magnitudes of CO₂ emission may be released to atmosphere where ponds are constructed in newly cleared mangrove forests. This study indicates the need for incentives that can meet the target of aquaculture industry without expanding the converted mangrove areas, which will lead to increased CO₂ released to atmosphere.

  18. Photosynthesis and fish production in culture ponds

    Energy Technology Data Exchange (ETDEWEB)

    Szyper, J.P.

    1995-12-31

    The widely-cultured Nile tilapia, Oreochromis niloticus, has been the major species used in standardized experiments by the Pond Dynamics/Aquaculture Collaborative Research Support Program (PD/ACRSP). Yields of Nile Tilapia from fertilized, unfed ponds have served as a bioassay for effectiveness of pond management protocols developed during worldwide tropical experiments. Yield rates near 10 T/ha/y can be achieved without feed inputs in ponds which maintain high standing stocks of phytoplankton and exhibit high rates near 10 T/ha/y can be achieved without feed inputs in ponds which maintain high standing stocks of phytoplankton and exhibit high rates of primary production. Fish production is related to daytime net photosynthetic production, but it is not clear whether production of food materials or oxygen is the more direct influence. Excessively high standing stocks of phytoplankton are not the best net producers, and increase and risk of nighttime oxygen depletion. Fish readily grow to individual sizes of 200-300 g/fish in fertilized ponds, which is sufficient market size in many locations. Supplemental feeding of caged or free-ranging fish greatly accelerates growth beyond 300 g and potentiates high areal yields; the PD/A CRSP has also developed efficient feeding regimes and shown that supplemental feeding need not begin before fish reach 200 g weight. High standing stocks of phytoplankton and high photosynthetic rates in eutrophic ponds make study of photosynthesis possible without radioisotopes. Such ponds also exhibit complete extinction of incident solar radiation within shallow depths, and vertical temperature structure resembling that of deeper bodies of water. These characteristics make ponds useful as microcosms for study of some aspects of photosynthesis in natural waters.

  19. WWER-type NPP spray ponds screen

    International Nuclear Information System (INIS)

    The objective of this study is to develop a protection screen of WWER-type NPP spray ponds. The screen design is to ensure reduction of the water droplets blown by the wind and, if possible, their return back to the spray ponds. The cooling capacity of the ponds is not to be changed below the design level for safety reasons. Computational fluid dynamics analysis is used to assess the influence of each design variant on the behavior of the water droplets distribution. Two variants are presented here. The one with plants is found not feasible. The second variant, with steel screen and terrain profile modification is selected for implementation. (author)

  20. ANL-W 779 pond seepage test

    International Nuclear Information System (INIS)

    The ANL-W 779 sanitary wastewater treatment ponds are located on the Idaho National Engineering Laboratory (INEL), north of the Argonne National Laboratory -- West (ANL-W) site A seepage test was performed for two Argonne National Laboratory -- West (ANL-W) sanitary wastewater treatment ponds, Facility 779. Seepage rates were measured to determine if the ponds are a wastewater land application facility. The common industry standard for wastewater land application facilities is a field-measured seepage rate of one quarter inch per day or greater

  1. 2MASS J18082002-5104378: The brightest (V=11.9) ultra metal-poor star

    CERN Document Server

    Melendez, Jorge; Tucci-Maia, Marcelo; Ramirez, Ivan; Li, Ting S; Perez, Gabriel

    2016-01-01

    Context. The most primitive metal-poor stars are important for studying the conditions of the early galaxy and are also relevant to big bang nucleosynthesis. Aims. Our objective is to find the brightest (V<14) most metal-poor stars. Methods. Candidates were selected using a new method, which is based on the mismatch between spectral types derived from colors and observed spectral types. They were observed first at low resolution with EFOSC2 at the NTT/ESO to obtain an initial set of stellar parameters. The most promising candidate, 2MASS J18082002-5104378 (V=11.9), was observed at high resolution (R=50 000) with UVES at the VLT/ESO, and a standard abundance analysis was performed. Results. We found that 2MASS J18082002-5104378 is an ultra metal-poor star with stellar parameters Teff = 5440 K, log g = 3.0 dex, vt = 1.5 km/s, [Fe/H] = -4.1 dex. The star has [C/Fe]<+0.9 in a 1D analysis, or [C/Fe]<=+0.5 if 3D effects are considered; its abundance pattern is typical of normal (non-CEMP) ultra metal-poor ...

  2. Information cascade on networks

    Science.gov (United States)

    Hisakado, Masato; Mori, Shintaro

    2016-05-01

    In this paper, we discuss a voting model by considering three different kinds of networks: a random graph, the Barabási-Albert (BA) model, and a fitness model. A voting model represents the way in which public perceptions are conveyed to voters. Our voting model is constructed by using two types of voters-herders and independents-and two candidates. Independents conduct voting based on their fundamental values; on the other hand, herders base their voting on the number of previous votes. Hence, herders vote for the majority candidates and obtain information relating to previous votes from their networks. We discuss the difference between the phases on which the networks depend. Two kinds of phase transitions, an information cascade transition and a super-normal transition, were identified. The first of these is a transition between a state in which most voters make the correct choices and a state in which most of them are wrong. The second is a transition of convergence speed. The information cascade transition prevails when herder effects are stronger than the super-normal transition. In the BA and fitness models, the critical point of the information cascade transition is the same as that of the random network model. However, the critical point of the super-normal transition disappears when these two models are used. In conclusion, the influence of networks is shown to only affect the convergence speed and not the information cascade transition. We are therefore able to conclude that the influence of hubs on voters' perceptions is limited.

  3. Superconducting cascade electron refrigerator

    Energy Technology Data Exchange (ETDEWEB)

    Camarasa-Gómez, M.; Giazotto, F. [NEST, Istituto Nanoscienze-CNR and Scuola Normale Superiore, 56127 Pisa (Italy); Di Marco, A.; Hekking, F. W. J. [LPMMC, CNRS and Université Joseph Fourier, 38042 Grenoble (France); Winkelmann, C. B.; Courtois, H. [Univ. Grenoble Alpes, Institut Néel, 38042 Grenoble (France); CNRS, Institut Néel, 38042 Grenoble (France)

    2014-05-12

    The design and operation of an electronic cooler based on a combination of superconducting tunnel junctions is described. The cascade extraction of hot-quasiparticles, which stems from the energy gaps of two different superconductors, allows for a normal metal to be cooled down to about 100 mK starting from a bath temperature of 0.5 K. We discuss the practical implementation, potential performance, and limitations of such a device.

  4. Quantum Cascade Detectors

    OpenAIRE

    Giorgetta, Fabrizio R.; Baumann, Esther; Graf, Marcel; Yang, Quankui; Manz, Christian; Köhler, Klaus; Beere, Harvey E.; Ritchie, David A.; Linfield, Edmund; Davies, Alexander G.; Fedoryshyn, Yuriy; Jackel, Heinz; Fischer, Milan; Faist, Jérôme; Hofstetter, Daniel

    2010-01-01

    This paper gives an overview on the design, fabrication, and characterization of quantum cascade detectors. They are tailorable infrared photodetectors based on intersubband transitions in semiconductor quantum wells that do not require an external bias voltage due to their asymmetric conduction band profile. They thus profit from favorable noise behavior, reduced thermal load, and simpler readout circuits. This was demonstrated at wavelengths from the near infrared at 2 μm to THz radiation a...

  5. Cascade ICF power reactor

    International Nuclear Information System (INIS)

    The double-cone-shaped Cascade reaction chamber rotates at 50 rpm to keep a blanket of ceramic granules in place against the wall as they slide from the poles to the exit slots at the equator. The 1 m-thick blanket consists of layers of carbon, beryllium oxide, and lithium aluminate granules about 1 mm in diameter. The x rays and debris are stopped in the carbon granules; the neutrons are multiplied and moderated in the BeO and breed tritium in the LiAlO2. The chamber wall is made up of SiO tiles held in compression by a network of composite SiC/Al tendons. Cascade operates at a 5 Hz pulse rate with 300 MJ in each pulse. The temperature in the blanket reaches 1600 K on the inner surface and 1350 K at the outer edge. The granules are automatically thrown into three separate vacuum heat exchangers where they give up their energy to high pressure helium. The helium is used in a Brayton cycle to obtain a thermal-to-electric conversion efficiency of 55%. Studies have been done on neutron activation, debris recovery, vaporization and recondensation of blanket material, tritium control and recovery, fire safety, and cost. These studies indicate that Cascade appears to be a promising ICF reactor candidate from all standpoints. At the 1000 MWe size, electricity could be made for about the same cost as in a future fission reactor

  6. Cascading to the MSSM

    CERN Document Server

    Heckman, Jonathan J; Verlinde, Herman; Wijnholt, Martijn

    2008-01-01

    The MSSM can arise as an orientifold of a pyramid-like quiver in the context of intersecting D-branes. Here we consider quiver realizations of the MSSM which can emerge at the bottom of a duality cascade. We classify all possible minimal ways this can be done by allowing only one extra node. It turns out that this requires extending the geometry of the pyramid to an octahedron. The MSSM at the bottom of the cascade arises in one of two possible ways, with the extra node disappearing either via Higgsing or confinement. Remarkably, the quiver of the Higgsing scenario turns out to be nothing but the quiver version of the left-right symmetric extension of the MSSM. In the minimal confining scenario the duality cascade can proceed if and only if there is exactly one up/down Higgs pair. Moreover, the symmetries of the octahedron naturally admit an automorphism of the quiver which solves a version of the mu problem precisely when there are an odd number of generations.

  7. Solar pond design for Arabian Gulf conditions

    Energy Technology Data Exchange (ETDEWEB)

    Hassab, M.A.; Tag, I.A.; Jassim, I.A.; Al-Juburi, F.Y.

    1987-01-01

    Collection and storage of solar energy in salt gradient solar ponds under conditions of high ambient and ground temperatures and all year-round sunny weather are investigated theoretically. A transient model based on measured local environmental conditions is developed to predict solar transmission, temperature distribution and salt distribution inside the pond for any day of the year. In the model the effects of heat dissipation into the ground, bottom reflection, pond dimensions, load extraction and variation of the pond's physical properties with temperature and concentration are investigated. The generated non-linear coupled system of heat and salt concentration equations for the composite media, considered to have isothermal boundary conditions, is solved numerically using the implicit finite-difference scheme.

  8. Status report on Fish Springs pond snail

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This report provides a life history of the pond snail (Lymnaea Hinkleyia pilsbryi) at Fish Springs National Wildlife Refuge. The following information is included;...

  9. South Bay Salt Ponds : Initial stewardship plan

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The California Department of Fish and Game and the U.S. Fish and Wildlife Service will operate and maintain the South Bay Salt Ponds under this Initial Stewardship...

  10. Wintertime Emissions from Produced Water Ponds

    Science.gov (United States)

    Evans, J.; Lyman, S.; Mansfield, M. L.

    2013-12-01

    Every year oil and gas drilling in the U.S. generates billions of barrels of produced water (water brought to the surface during oil or gas production). Efficiently disposing of produced water presents a constant financial challenge for producers. The most noticeable disposal method in eastern Utah's Uintah Basin is the use of evaporation ponds. There are 427 acres of produced water ponds in the Uintah Basin, and these were used to evaporate more than 5 million barrels of produced water in 2012, 6% of all produced water in the Basin. Ozone concentrations exceeding EPA standards have been observed in the Uintah Basin during winter inversion conditions, with daily maximum 8 hour average concentrations at some research sites exceeding 150 parts per billion. Produced water contains ozone-forming volatile organic compounds (VOC) which escape into the atmosphere as the water is evaporated, potentially contributing to air quality problems. No peer-reviewed study of VOC emissions from produced water ponds has been reported, and filling this gap is essential for the development of accurate emissions inventories for the Uintah Basin and other air sheds with oil and gas production. Methane, carbon dioxide, and VOC emissions were measured at three separate pond facilities in the Uintah Basin in February and March of 2013 using a dynamic flux chamber. Pond emissions vary with meteorological conditions, so measurements of VOC emissions were collected during winter to obtain data relevant to periods of high ozone production. Much of the pond area at evaporation facilities was frozen during the study period, but areas that actively received water from trucks remained unfrozen. These areas accounted for 99.2% of total emissions but only 9.5% of the total pond area on average. Ice and snow on frozen ponds served as a cap, prohibiting VOC from being emitted into the atmosphere. Emissions of benzene, toluene, and other aromatic VOCs averaged over 150 mg m-2 h-1 from unfrozen pond

  11. Radioecological implications of the Par Pond drawdown

    International Nuclear Information System (INIS)

    The drawdown of the Par Pond reservoir created dramatic alterations in this formerly stable lentic ecosystem. In addition, the radiation environment at Par Pond has changed significantly because of the exposure of Cesium 137-contaminated sediments and the appearance of new transport pathways to the terrestrial environment. In response to this situation, SREL was asked to study the radioecological implications of the reservoir drawdown. This report contains the objectives, methods, and results of the SREL study

  12. Biological traits of European pond macroinvertebrates

    OpenAIRE

    Céréghino, Régis; Oertli, Beat; Marcello BAZZANTI; Coccia, Cristina; Compin, Arthur; Biggs, Jeremy; Bressi, Nicolas; Grillas, Patrick; Hull, Andrew P.; Kalettka, Thomas; Scher, Olivier

    2012-01-01

    Whilst biological traits of river macroinvertebrates show unimodal responses to geographic changes in habitat conditions in Europe, we still do not know whether spatial turnover of species result in distinct combinations of biological traits for pond macroinvertebrates. Here, we used data on the occurrence of 204 macroinvertebrate taxa in 120 ponds from four biogeographic regions of Europe, to compare their biological traits. The Mediterranean, Atlantic, Alpine, and Continental regions have s...

  13. History, origins and importance of temporary ponds

    OpenAIRE

    Williams, Penny; Biggs, Jeremy; Fox, Gill; Nicolet, Pascale; Whitfield, Merica

    2001-01-01

    In Europe, temporary ponds are a naturally common and widespread habitat occurring, often in abundance, in all biogeographical regions from the boreal snow-melt pools of northern Scandinavia to the seasonally inundated coastal dune pools of southern Spain. Ecological studies in Europe and elsewhere also emphasise that temporary ponds are a biologically important habitat type, renowned both for their specialised assemblages and the considerable numbers of rare and endemic species they support....

  14. Displacement cascades in polyatomic materials

    Energy Technology Data Exchange (ETDEWEB)

    Parkin, D.M.; Coulter, C.A.

    1982-01-01

    Using a continuous-slowing-down, random amorphous material model, we have studied displacement cascades in a number of diatomic materials. This paper reviews a number of previous results that elucidate the effects of atomic mass, recoil energy, displacement energy, capture energy and material stoichiometry on the numbers of displacements in a cascade. The displacement cascade reveals a complex structure that is dependent on the type of irradiation and the material properties. Conclusions related to damage analysis for fusion reactors are given.

  15. Quantum dot cascade laser

    OpenAIRE

    Zhuo, Ning; Liu, Feng Qi; Zhang, Jin Chuan; Wang, Li Jun; Liu, Jun Qi; Zhai, Shen Qiang; Wang, Zhan Guo

    2014-01-01

    We demonstrated an unambiguous quantum dot cascade laser based on InGaAs/GaAs/InAs/InAlAs heterostructure by making use of self-assembled quantum dots in the Stranski-Krastanow growth mode and two-step strain compensation active region design. The prototype generates stimulated emission at λ ~ 6.15 μm and a broad electroluminescence band with full width at half maximum over 3 μm. The characteristic temperature for the threshold current density within the temperature range of 82 to 162 K is up...

  16. Quantum dot cascade laser

    Science.gov (United States)

    2014-01-01

    We demonstrated an unambiguous quantum dot cascade laser based on InGaAs/GaAs/InAs/InAlAs heterostructure by making use of self-assembled quantum dots in the Stranski-Krastanow growth mode and two-step strain compensation active region design. The prototype generates stimulated emission at λ ~ 6.15 μm and a broad electroluminescence band with full width at half maximum over 3 μm. The characteristic temperature for the threshold current density within the temperature range of 82 to 162 K is up to 400 K. Moreover, our materials show the strong perpendicular mid-infrared response at about 1,900 cm-1. These results are very promising for extending the present laser concept to terahertz quantum cascade laser, which would lead to room temperature operation. PACS 42.55.Px; 78.55.Cr; 78.67.Hc PMID:24666965

  17. Event-based stormwater management pond runoff temperature model

    Science.gov (United States)

    Sabouri, F.; Gharabaghi, B.; Sattar, A. M. A.; Thompson, A. M.

    2016-09-01

    Stormwater management wet ponds are generally very shallow and hence can significantly increase (about 5.4 °C on average in this study) runoff temperatures in summer months, which adversely affects receiving urban stream ecosystems. This study uses gene expression programming (GEP) and artificial neural networks (ANN) modeling techniques to advance our knowledge of the key factors governing thermal enrichment effects of stormwater ponds. The models developed in this study build upon and compliment the ANN model developed by Sabouri et al. (2013) that predicts the catchment event mean runoff temperature entering the pond as a function of event climatic and catchment characteristic parameters. The key factors that control pond outlet runoff temperature, include: (1) Upland Catchment Parameters (catchment drainage area and event mean runoff temperature inflow to the pond); (2) Climatic Parameters (rainfall depth, event mean air temperature, and pond initial water temperature); and (3) Pond Design Parameters (pond length-to-width ratio, pond surface area, pond average depth, and pond outlet depth). We used monitoring data for three summers from 2009 to 2011 in four stormwater management ponds, located in the cities of Guelph and Kitchener, Ontario, Canada to develop the models. The prediction uncertainties of the developed ANN and GEP models for the case study sites are around 0.4% and 1.7% of the median value. Sensitivity analysis of the trained models indicates that the thermal enrichment of the pond outlet runoff is inversely proportional to pond length-to-width ratio, pond outlet depth, and directly proportional to event runoff volume, event mean pond inflow runoff temperature, and pond initial water temperature.

  18. Accumulation of Pollutants in Highway Detention Ponds

    DEFF Research Database (Denmark)

    Bentzen, Thomas Ruby

    This PhD study deals with issues related to water and pollutant transport from highway surfaces caused by rain. It is essential in the study to apply methods and models in which improvements in relation to removal of pollutants can be identified and to be able to predict the yearly discharges of...... single rain event. From the hindcast results it is possible to calculate mean water and pollutant loads. This method is commonly used in urban drainage systems for capacity analysis or for prediction of CSO's. The challenge is to develop a simplified and still accurate description of flow and transport....... Measurements of water and pollutant transport are carried out in different highway systems. A geometrically well-defined test pond is established, wherein the deposition of particulate matter can be measured. The result from the test pond is transferred to real detention ponds in which the three...

  19. Cascade Error Projection Learning Algorithm

    Science.gov (United States)

    Duong, T. A.; Stubberud, A. R.; Daud, T.

    1995-01-01

    A detailed mathematical analysis is presented for a new learning algorithm termed cascade error projection (CEP) and a general learning frame work. This frame work can be used to obtain the cascade correlation learning algorithm by choosing a particular set of parameters.

  20. Cascade Distillation System Development

    Science.gov (United States)

    Callahan, Michael R.; Sargushingh, Miriam; Shull, Sarah

    2014-01-01

    NASA's Advanced Exploration Systems (AES) Life Support System (LSS) Project is chartered with de-veloping advanced life support systems that will ena-ble NASA human exploration beyond low Earth orbit (LEO). The goal of AES is to increase the affordabil-ity of long-duration life support missions, and to re-duce the risk associated with integrating and infusing new enabling technologies required to ensure mission success. Because of the robust nature of distillation systems, the AES LSS Project is pursuing develop-ment of the Cascade Distillation Subsystem (CDS) as part of its technology portfolio. Currently, the system is being developed into a flight forward Generation 2.0 design.

  1. Bioaccumulation of heavy metals in two wet retention ponds

    DEFF Research Database (Denmark)

    Søberg, Laila C.; Vollertsen, Jes; Blecken, Godecke-Tobias; Nielsen, Asbjørn Haaning; Viklander, Maria

    2016-01-01

    Metal accumulation in stormwater ponds may contaminate the inhabiting fauna, thus jeopardizing their ecosystem servicing function. We evaluated bioaccumulation of metals in natural fauna and caged mussel indicator organisms in two wet retention ponds. Mussel cages were distributed throughout the ...

  2. Sea Ice Melt Pond Data from the Canadian Arctic

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set contains observations of albedo, depth, and physical characteristics of melt ponds on sea ice, taken during the summer of 1994. The melt ponds studied...

  3. Fuel element storage pond for nuclear installations

    International Nuclear Information System (INIS)

    In a fuel element storage pond for nuclear installations, with different water levels, radioactive particles are deposited at the points of contact of the water surface with the pond wall. So that this deposition will not occur, a metal apron is provided in the area of the points of contact of the water surface with the bond wall. The metal apron consists of individual sheets of metal which are suspended by claws in wall hooks. To clean the sheets, these are moved to a position below the water level. The sheets are suspended from the wall hooks during this process. (orig.)

  4. Interband cascade lasers

    Science.gov (United States)

    Vurgaftman, I.; Weih, R.; Kamp, M.; Meyer, J. R.; Canedy, C. L.; Kim, C. S.; Kim, M.; Bewley, W. W.; Merritt, C. D.; Abell, J.; Höfling, S.

    2015-04-01

    We review the current status of interband cascade lasers (ICLs) emitting in the midwave infrared (IR). The ICL may be considered the hybrid of a conventional diode laser that generates photons via electron-hole recombination, and an intersubband-based quantum cascade laser (QCL) that stacks multiple stages for enhanced current efficiency. Following a brief historical overview, we discuss theoretical aspects of the active region and core designs, growth by molecular beam epitaxy, and the processing of broad-area, narrow-ridge, and distributed feedback (DFB) devices. We then review the experimental performance of pulsed broad area ICLs, as well as the continuous-wave (cw) characteristics of narrow ridges having good beam quality and DFBs producing output in a single spectral mode. Because the threshold drive powers are far lower than those of QCLs throughout the λ = 3-6 µm spectral band, ICLs are increasingly viewed as the laser of choice for mid-IR laser spectroscopy applications that do not require high output power but need to be hand-portable and/or battery operated. Demonstrated ICL performance characteristics to date include threshold current densities as low as 106 A cm-2 at room temperature (RT), cw threshold drive powers as low as 29 mW at RT, maximum cw operating temperatures as high as 118 °C, maximum cw output powers exceeding 400 mW at RT, maximum cw wallplug efficiencies as high as 18% at RT, maximum cw single-mode output powers as high as 55 mW at RT, and single-mode output at λ = 5.2 µm with a cw drive power of only 138 mW at RT.

  5. Interband cascade lasers

    International Nuclear Information System (INIS)

    We review the current status of interband cascade lasers (ICLs) emitting in the midwave infrared (IR). The ICL may be considered the hybrid of a conventional diode laser that generates photons via electron–hole recombination, and an intersubband-based quantum cascade laser (QCL) that stacks multiple stages for enhanced current efficiency. Following a brief historical overview, we discuss theoretical aspects of the active region and core designs, growth by molecular beam epitaxy, and the processing of broad-area, narrow-ridge, and distributed feedback (DFB) devices. We then review the experimental performance of pulsed broad area ICLs, as well as the continuous-wave (cw) characteristics of narrow ridges having good beam quality and DFBs producing output in a single spectral mode. Because the threshold drive powers are far lower than those of QCLs throughout the λ = 3–6 µm spectral band, ICLs are increasingly viewed as the laser of choice for mid-IR laser spectroscopy applications that do not require high output power but need to be hand-portable and/or battery operated. Demonstrated ICL performance characteristics to date include threshold current densities as low as 106 A cm−2 at room temperature (RT), cw threshold drive powers as low as 29 mW at RT, maximum cw operating temperatures as high as 118 °C, maximum cw output powers exceeding 400 mW at RT, maximum cw wallplug efficiencies as high as 18% at RT, maximum cw single-mode output powers as high as 55 mW at RT, and single-mode output at λ = 5.2 µm with a cw drive power of only 138 mW at RT. (topical review)

  6. Detention Pond Sediment Accumulation Prediction using Monte Carlo Simulation

    OpenAIRE

    Supiah Shamsudin; Abd R.M. Darom; Irma N. Mohamad; Azmi A. Rahman

    2012-01-01

    Problem statement: A study in Malaysia had been carried out to predict the sediment accumulation in urban detention ponds. Suspended sediment is pollutant of primary concern to the river that results in adverse environmental effect. Detention pond becomes a practical approach to this problem. Suspended sediment that settled in stormwater detention pond, can bring effect to the detention pond functions. Questions were raised on how certain were the observed and predicted values of sediment dep...

  7. Retrieval of Melt Pond Coverage from MODIS using Optimal Estimation

    OpenAIRE

    Dodd, Emma

    2011-01-01

    Melt pond coverage on sea ice is an important influence on sea ice albedo reduction during the summer and can also affect the monitoring of sea ice extent, sea ice models and sea ice forecasting. Techniques to estimate melt pond coverage from global satellites have been developed in order to provide large scale information on melt ponds, but these techniques have limitations. In this study a new approach to estimating melt pond coverage from MODIS data was developed, based on Optimal Estimati...

  8. Cyanobacterial biodiversity from different freshwater ponds of Thanjavur, Tamilnadu (India)

    OpenAIRE

    Muthukumar, Chinnasamy; Muralitharan, Gangatharan; Vijayakumar, Ramasamy; Panneerselvam, Annamalai; Thajuddin, Nooruddin

    2007-01-01

    Cyanobacterial biodiversity from different freshwater ponds of Thanjavur, Tamilnadu (India). Studies on the cyanobacterial biodiversity of 5 different freshwater ponds in and around Thanjavur, Tamilnadu during summer month (June, 2004) has been made and compared their variations among five different ponds. In addition, certain physico-chemical parameters of pond waters such as dissolved oxygen, net productivity, pH, carbonate, bicarbonate, nitrate, nitrite, total phosphorus, inorganic phospho...

  9. Plankton biomass in secondary ponds treating piggery waste

    OpenAIRE

    Lígia Barthel; Paulo Armando Victória de Oliveira; Rejane Helena Ribeiro da Costa

    2008-01-01

    This study aimed at analyzing the plankton biomass found in a piggery waste treatment system, composed of a high rate algal pond (HRAP), two maturation ponds (MP1, MP2) (System A) and a water hyacinth pond (WHP) (System B). The ponds were disposed in series and the study was performed for 32 weeks. The physicochemical variables monitored were: pH, temperature, dissolved oxygen, soluble chemical oxygen demand, nitrogen compounds and total phosphorus. The plankton biomass was identified at genu...

  10. Investigation of abandoned surface settling ponds

    International Nuclear Information System (INIS)

    One of the problems that may appear during the ground reclamation of surface settling ponds of underground mines is enhanced radon exhalation from bottom sediments. This problem becomes more important when the concentration of radium isotopes in sediments is enhanced due to the discharge of radium-bearing waters into the pond. For investigations, special radon accumulation chambers have been designed and constructed. The concentration of radon in these chambers can be measured with the application of Lucas cells or activated charcoal detectors. In the latter method, radon is extracted from charcoal into a liquid scintillator and the sample is measured in a liquid scintillation spectrometer. Therefore the lower limit of detection (LLD) of the second method is as low as 0.1 mBq·m-2s-1, while the LLD for Lucas cells is 1.5 mBq·m-2s-1. The above-mentioned methods for the measurement of radon exhalation have been applied to investigations of a surface settling pond of one Polish coal mine, abandoned and emptied at the beginning of 2002. An agreement between the mine management and the local authority was to make the ground reclamation of the pond. A thick layer of sediments with an enhanced concentration of radium isotopes covers the bottom of the pond. The maximum concentration of radium isotopes in these sediments is as high as 2000 Bq/kg for 226Ra and up to 4000 Bq/kg for 228Ra. Two years after the complete release of brines from the pond, bottom sediments are still soaked with water. Therefore, measurements of radon in soil gas were not possible. On the other hand, in some parts of the pond investigations of radon exhalation coefficient were done. The preliminary results of measurements, conducted in 2002, showed that radon exhalation rates in specific parts of the pond were higher than the highest values of radon exhalation from the ground in the Upper Silesia region. Values of exhalation coefficient up to 200 mBq·m-2s-1 were found. It must be pointed out that

  11. Separation of carrier-free holmium and dysprosium produced in 70 MeV 11B5+ irradiated europium target by liquid-liquid extraction with HDEHP

    International Nuclear Information System (INIS)

    Heavy ion activation of natural europium oxide with 70 MeV 11B5+ results in the formation of carrier-free erbium isotopes, 157-160Er, and their corresponding decay products, 158-160Ho and 157Dy in the matrix. Carrier-free holmium and dysprosium isotopes have been separated from the bulk target matrix europium by employing di-(2-ethylhexyl)phosphoric acid (HDEHP) as a liquid cation exchanger. (author)

  12. Nat'l_Register, ContributingResources, The Ponds at Pipe Spring National Monument, Arizona (pisp_ponds)

    Data.gov (United States)

    National Park Service, Department of the Interior — This is an Arc/Info coverage consisting of 2 polygons representing the ponds at Pipe Spring National Monument, Arizona. The ponds were collected by a Trimble GeoXT...

  13. 33 CFR 117.598 - Eel Pond Channel.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Eel Pond Channel. 117.598 Section... DRAWBRIDGE OPERATION REGULATIONS Specific Requirements Massachusetts § 117.598 Eel Pond Channel. The following requirements apply to the draw of Eel Pond (Water Street) drawbridge at mile 0.0 at...

  14. Heat extraction from a salinity-gradient solar pond using in pond heat exchanger

    Energy Technology Data Exchange (ETDEWEB)

    Jaefarzadeh, M.R. [Civil Engineering Department, Ferdowsi University of Mashhad, P.O. Box 91775-1111 Mashhad (Iran)

    2006-11-15

    Thermal energy extraction from a small salinity-gradient solar pond is studied in this article. The small pond has an area of 4.0m{sup 2} and a depth of 1.1m. Fresh water circulates through an internal heat exchanger, located in the lower convective zone, and transfers its thermal energy to an external heat exchanger. The study covers two periods of summer loading for a week and winter loading for two months. The hourly as well as daily variations of the temperatures of the storage zone, surface zone, ambient, inlet and outlet of the internal heat exchanger have been measured and analyzed. It is shown that the pond may deliver heat with a relatively high thermal efficiency in a transitional stage for a limited period of time. It can also be utilized continuously with a lower efficiency. The efficiency of the small pond in the latter case will be around 10%. (author)

  15. Fate of Pyrethroids in Farmland Ponds

    DEFF Research Database (Denmark)

    Mogensen, B. B.; Sørensen, P. B.; Stuer-Lauridsen, F.;

    Pyrethroids constitute a group of widely used insecticides, which are toxic to aquatic organisms. This report presents the results from a 2-year study of the fate of pyrethroids in ponds, i.e. their distribution in the water column, the sediment and the surface microlayer respectively. The...

  16. Ecology of Great Salt Pond, Block Island

    Science.gov (United States)

    Great Salt Pond is an island of estuarine water on Block Island, which sits in the middle of the Northwest Atlantic Continental Shelf. When the last continental glaciers retreated, they left a high spot on a terminal moraine. The rising sea from melting glaciers formed two island...

  17. Interconnected ponds operation for flood hazard distribution

    Science.gov (United States)

    Putra, S. S.; Ridwan, B. W.

    2016-05-01

    The climatic anomaly, which comes with extreme rainfall, will increase the flood hazard in an area within a short period of time. The river capacity in discharging the flood is not continuous along the river stretch and sensitive to the flood peak. This paper contains the alternatives on how to locate the flood retention pond that are physically feasible to reduce the flood peak. The flood ponds were designed based on flood curve number criteria (TR-55, USDA) with the aim of rapid flood peak capturing and gradual flood retuning back to the river. As a case study, the hydrologic condition of upper Ciliwung river basin with several presumed flood pond locations was conceptually designed. A fundamental tank model that reproducing the operation of interconnected ponds was elaborated to achieve the designed flood discharge that will flows to the downstream area. The flood hazard distribution status, as the model performance criteria, will be computed within Ciliwung river reach in Manggarai Sluice Gate spot. The predicted hazard reduction with the operation of the interconnected retention area result had been bench marked with the normal flow condition.

  18. Aquatic Habitats: Exploring Desktop Ponds. Teacher's Guide.

    Science.gov (United States)

    Barrett, Katharine; Willard, Carolyn

    This book, for grades 2-6, is designed to provide students with a highly motivating and unique opportunity to investigate an aquatic habitat. Students set up, observe, study, and reflect upon their own "desktop ponds." Accessible plants and small animals used in these activities include Elodea, Tubifex worms, snails, mosquito larvae, and fish.…

  19. Pond fractals in a tidal flat.

    Science.gov (United States)

    Cael, B B; Lambert, Bennett; Bisson, Kelsey

    2015-11-01

    Studies over the past decade have reported power-law distributions for the areas of terrestrial lakes and Arctic melt ponds, as well as fractal relationships between their areas and coastlines. Here we report similar fractal structure of ponds in a tidal flat, thereby extending the spatial and temporal scales on which such phenomena have been observed in geophysical systems. Images taken during low tide of a tidal flat in Damariscotta, Maine, reveal a well-resolved power-law distribution of pond sizes over three orders of magnitude with a consistent fractal area-perimeter relationship. The data are consistent with the predictions of percolation theory for unscreened perimeters and scale-free cluster size distributions and are robust to alterations of the image processing procedure. The small spatial and temporal scales of these data suggest this easily observable system may serve as a useful model for investigating the evolution of pond geometries, while emphasizing the generality of fractal behavior in geophysical surfaces. PMID:26651668

  20. Intermediate Pond Sizes Contain the Highest Density, Richness, and Diversity of Pond-Breeding Amphibians

    OpenAIRE

    Semlitsch, Raymond D.; William E Peterman; Anderson, Thomas L.; Drake, Dana L.; Brittany H Ousterhout

    2015-01-01

    We present data on amphibian density, species richness, and diversity from a 7140-ha area consisting of 200 ponds in the Midwestern U.S. that represents most of the possible lentic aquatic breeding habitats common in this region. Our study includes all possible breeding sites with natural and anthropogenic disturbance processes that can be missing from studies where sampling intensity is low, sample area is small, or partial disturbance gradients are sampled. We tested whether pond area was a...

  1. Prevention of sewage pollution by stabilization ponds.

    Science.gov (United States)

    Lakshminarayana, J S

    1975-01-01

    Water is polluted when it constitutes a health hazard or when its usefulness is impaired. The major sources of water pollution are municipal, manufacturing, mining, steam, electric power, cooling and agricultural. Municipal or sewage pollution forms a greater part of the man's activity and it is the immediate need of even smaller communities of today to combat sewage pollution. It is needless to stress that if an economic balance of the many varied services which a stream or a body of water is called upon to render is balanced and taken into consideration one could think of ending up in a wise management programme. In order to eliminate the existing water pollutional levels of the natural water one has to think of preventive and treatment methods. Of the various conventional and non-conventional methods of sewage treatment known today, in India, where the economic problems are complex, the waste stabilization ponds have become popular over the last two decades to let Public Health Engineers use them with confidence as a simple and reliable means of treatment of sewage and certain industrial wastes, at a fraction of the cost of conventional waste treatment plants used hitherto. A waste stabilization pond makes use of natural purification processes involved in an ecosystem through the regulating of such processes. The term "waste stabilization pond" in its simplest form is applied to a body of water, artificial or natural, employed with the intention of retaining sewage or organic waste waters until the wastes are rendered stable and inoffensive for discharge into receiving waters or on land, through physical, chemical and biological processes commonly referred to as "self-purification" and involving the symbiotic action of algae and bacteria under the influence of sunlight and air. Organic matter contained in the waste is stabilized and converted in the pond into more stable matter in the form of algal cells which find their way into the effluent and hence the term

  2. Heavy metals, PAHs and toxicity in stormwater wet detention ponds

    DEFF Research Database (Denmark)

    Wium-Andersen, Tove; Nielsen, Asbjørn Haaning; Hvitved-Jacobsen, Thorkild;

    2011-01-01

    Concentrations of 6 different heavy metals and total Polycyclic Aromatic Hydrocarbons (PAH) were determined in stormwater runoff and in the pond water of two Danish wet detention ponds. The pond water samples were analyzed for toxic effects, using the algae Selenastrum capricornutum as a test...... organism. Stormwater and pond water from a catchment with light industry showed high levels of heavy metals, especially zinc and copper. The pond water showed high toxic effects and copper were found to be the main toxicant. Additionally, a large part of the copper was suspected to be complex bound...

  3. Cascade redox flow battery systems

    Science.gov (United States)

    Horne, Craig R.; Kinoshita, Kim; Hickey, Darren B.; Sha, Jay E.; Bose, Deepak

    2014-07-22

    A reduction/oxidation ("redox") flow battery system includes a series of electrochemical cells arranged in a cascade, whereby liquid electrolyte reacts in a first electrochemical cell (or group of cells) before being directed into a second cell (or group of cells) where it reacts before being directed to subsequent cells. The cascade includes 2 to n stages, each stage having one or more electrochemical cells. During a charge reaction, electrolyte entering a first stage will have a lower state-of-charge than electrolyte entering the nth stage. In some embodiments, cell components and/or characteristics may be configured based on a state-of-charge of electrolytes expected at each cascade stage. Such engineered cascades provide redox flow battery systems with higher energy efficiency over a broader range of current density than prior art arrangements.

  4. Ultrarelativistic cascades and strangeness production

    Energy Technology Data Exchange (ETDEWEB)

    Kahana, D.E. [State Univ. of New York, Stony Brook, NY (United States). Dept. of Physics; Kahana, S.H. [Brookhaven National Lab., Upton, NY (United States). Physics Dept.

    1998-08-24

    A two-phase cascade code, LUCIFER II, developed for the treatment of ultra high energy-ion-ion collisions is applied to the production of strangeness at SPS energies {radical}(s)=17-20. This simulation is able to simultaneously describe both hard processes such as Drell-Yan and slower, soft processes such as the production of light mesons by separating the dynamics into two steps, a fast cascade involving only the nucleons in the original colliding relativistic ions followed, after an appropriate delay, by a normal multiscattering of the resulting excited baryons and mesons produced virtually in the first step. No energy loss can take place in the short time interval over which the first cascade takes place. The chief result is a reconciliation of the important Drell-Yan measurements with the apparent success of standard cascades to describe the nucleon stopping and meson production in heavy-ion experiments at the CERN SPS. (orig.) 26 refs.

  5. Ultrarelativistic cascades and strangeness production

    International Nuclear Information System (INIS)

    A two-phase cascade code, LUCIFER II, developed for the treatment of ultra high energy-ion-ion collisions is applied to the production of strangeness at SPS energies √(s)=17-20. This simulation is able to simultaneously describe both hard processes such as Drell-Yan and slower, soft processes such as the production of light mesons by separating the dynamics into two steps, a fast cascade involving only the nucleons in the original colliding relativistic ions followed, after an appropriate delay, by a normal multiscattering of the resulting excited baryons and mesons produced virtually in the first step. No energy loss can take place in the short time interval over which the first cascade takes place. The chief result is a reconciliation of the important Drell-Yan measurements with the apparent success of standard cascades to describe the nucleon stopping and meson production in heavy-ion experiments at the CERN SPS. (orig.)

  6. Ultrarelativistic cascades and strangeness production

    Energy Technology Data Exchange (ETDEWEB)

    Kahana, D.E. [State Univ. of New York, Stony Brook, NY (United States). Physics Dept.; Kahana, S.H. [Brookhaven National Lab., Upton, NY (United States). Physics Dept.

    1998-02-01

    A two phase cascade, LUCIFER II, developed for the treatment of ultra high energy Ion-Ion collisions is applied to the production of strangeness at SPS energies. This simulation is able to simultaneously describe both hard processes such as Drell-Yan and slower, soft processes such as the production of light mesons by separating the dynamics into two steps, a fast cascade involving only the nucleons in the original colliding relativistic ions followed, after an appropriate delay, by a normal multiscattering of the resulting excited baryons and mesons produced virtually in the first step. No energy loss can take place in the short time interval over which the first cascade takes place. The chief result is a reconciliation of the important Drell-Yan measurements with the apparent success of standard cascades to describe the nucleon stopping and meson production in heavy ion experiments at the CERN SPS.

  7. Microbial activities and communities in oil sands tailings ponds

    Energy Technology Data Exchange (ETDEWEB)

    Gieg, Lisa; Ramos, Esther; Clothier, Lindsay; Bordenave, Sylvain; Lin, Shiping; Voordouw, Gerrit; Dong, Xiaoli; Sensen, Christoph [University of Calgary (Canada)

    2011-07-01

    This paper discusses how the microbial communities and their activity play a vital role in tailings ponds. The ponds contain microorganisms along with metals, hydrocarbon diluent, naphthenic acid and others. The ponds play an important role in mining operations because they store bitumen extraction waste and also allow water to be re-used in the bitumen extraction process. Pond management presents a few challenges that include, among others, gas emissions and the presence of toxic and corrosive acids. Microbial activities and communities help in managing these ponds. Microbial activity measurement in active and inactive ponds is described and analyzed and the results are presented. The conditions for reducing sulfate, nitrate and iron are also presented. From the results it can be concluded that naphthenic acids can potentially serve as substrates for anaerobic populations in tailings ponds.

  8. Insect diversity and water quality parameters of two ponds of Chatla wetland, Barak valley, Assam

    Directory of Open Access Journals (Sweden)

    Susmita Gupta

    2012-12-01

    Full Text Available An investigation was carried out on two ponds of Chatla floodplain, Barak valley, Assam with special reference to aquatic insects. Pond 1 is purely a fish pond where as pond 2 is a community pond too. Present study revealed the status of water quality and in turn diversity, density, dominance and abundance of aquatic insects in both the ponds. Almost all the physico chemical parameters of both the ponds were found within permissible range for aquatic life .However in pond 2 level of phosphate was found little higher than pond 1 due to release of soaps and detergents by human influence. In both the ponds order Hemiptera showed maximum relative abundance ( 98% in pond 1 and 94% in pond 2. The study revealed lower diversity of aquatic insects in pond 2 than that in pond 1.

  9. Interband Cascade Photovoltaic Cells

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Rui Q. [Univ. of Oklahoma, Norman, OK (United States); Santos, Michael B. [Univ. of Oklahoma, Norman, OK (United States); Johnson, Matthew B. [Univ. of Oklahoma, Norman, OK (United States)

    2014-09-24

    In this project, we are performing basic and applied research to systematically investigate our newly proposed interband cascade (IC) photovoltaic (PV) cells [1]. These cells follow from the great success of infrared IC lasers [2-3] that pioneered the use of quantum-engineered IC structures. This quantum-engineered approach will enable PV cells to efficiently convert infrared radiation from the sun or other heat source, to electricity. Such cells will have important applications for more efficient use of solar energy, waste-heat recovery, and power beaming in combination with mid-infrared lasers. The objectives of our investigations are to: achieve extensive understanding of the fundamental aspects of the proposed PV structures, develop the necessary knowledge for making such IC PV cells, and demonstrate prototype working PV cells. This research will focus on IC PV structures and their segments for utilizing infrared radiation with wavelengths from 2 to 5 μm, a range well suited for emission by heat sources (1,000-2,000 K) that are widely available from combustion systems. The long-term goal of this project is to push PV technology to longer wavelengths, allowing for relatively low-temperature thermal sources. Our investigations address material quality, electrical and optical properties, and their interplay for the different regions of an IC PV structure. The tasks involve: design, modeling and optimization of IC PV structures, molecular beam epitaxial growth of PV structures and relevant segments, material characterization, prototype device fabrication and testing. At the end of this program, we expect to generate new cutting-edge knowledge in the design and understanding of quantum-engineered semiconductor structures, and demonstrate the concepts for IC PV devices with high conversion efficiencies.

  10. A Cascading Failure Model by Quantifying Interactions

    OpenAIRE

    Qi, Junjian; Mei, Shengwei

    2013-01-01

    Cascading failures triggered by trivial initial events are encountered in many complex systems. It is the interaction and coupling between components of the system that causes cascading failures. We propose a simple model to simulate cascading failure by using the matrix that determines how components interact with each other. A careful comparison is made between the original cascades and the simulated cascades by the proposed model. It is seen that the model can capture general features of t...

  11. Phase transformations during heat treatment of W-Mo-V 11-2-2 type high-speed steels with increased contents of Si and Nb or Ti

    Energy Technology Data Exchange (ETDEWEB)

    Dobrzanski, L.A.; Zarychta, A.; Ligarski, M. [Division of Tool Materials and Computer Techniques in Metal Service, Silesian Technical University, Gliwice (Poland)

    1995-12-31

    The paper presents results of investigations in W-Mo-V 11-2-2 high-speed steels with a part of vanadium substituted with niobium or titanium. The optimum combinations of 0.5%Nb or 0.3%Ti with 1.6%V gave maximum hardness of 65.5-66 HRC after tempering at 570-540{sup o}C, respectively. In all steels covered by the study secondary hardening was due chiefly to precipitation of fine M{sub 4}C{sub 3} carbides in martensite and martensitic transformation of retained austenite into {alpha} phase. (author). 14 refs, 3 tabs.

  12. Phase transformations during heat treatment of W-Mo-V 11-2-2 type high-speed steels with increased contents of Si and Nb or Ti

    International Nuclear Information System (INIS)

    The paper presents results of investigations in W-Mo-V 11-2-2 high-speed steels with a part of vanadium substituted with niobium or titanium. The optimum combinations of 0.5%Nb or 0.3%Ti with 1.6%V gave maximum hardness of 65.5-66 HRC after tempering at 570-540oC, respectively. In all steels covered by the study secondary hardening was due chiefly to precipitation of fine M4C3 carbides in martensite and martensitic transformation of retained austenite into α phase. (author)

  13. Maintenance strategy for a salt gradient solar pond coupled with an evaporation pond

    Energy Technology Data Exchange (ETDEWEB)

    Agha, K.R.; Abughres, S.M.; Ramadan, A.M. [CSES, Tripoli (Libya). Center for Solar Energy Studies

    2004-07-01

    In a previous study, the authors presented a simple mathematical model for predicting the ratio of the evaporation pond area to that of a salt gradient solar pond area. The evaporation pond idea provides a very attractive method of salt recycling by evaporation, especially in areas of high evaporation and low rates of rain as it is the case for North Africa. In this paper, the model was elaborated upon and applied to two types of surface water flushing (fresh water and seawater) under the prevailing conditions of Tripoli, Libya (latitude = 32.86{sup o}N). All the results presented were predicted for the first three years of operation. The daily variations of brine concentration in the of Tajoura's Experimental Solar pond and those based on different designs were predicted and discussed under different scenarios. The quantities of brine provided by the evaporation pond and that required by were predicted for both cases of surface water flushing (fresh water and seawater) under the different design conditions. It was predicted that the can provide 20-40% during the first year and 45-95% during the third year depending on the design selected. (author)

  14. Engineered design of SSC cooling ponds

    International Nuclear Information System (INIS)

    The cooling requirements of the SSC are significant and adequate cooling water systems to meet these requirements are critical to the project's successful operation. The use of adequately designed cooling ponds will provide reliable cooling for operation while also meeting environmental goals of the project to maintain streamflow and flood peaks to preconstruction levels as well as other streamflow and water quality requirements of the Texas Water Commission and the Environmental Protection Agency

  15. Par Pond refill water quality sampling

    International Nuclear Information System (INIS)

    This study was designed to document anoxia and its cause in the event that the anoxia caused a fish kill. However, no fish kill was observed during this study, and dissolved oxygen and nutrient concentrations generally remained within the range expected for southeastern reservoirs. Par Pond water quality monitoring will continue during the second summer after refill as the aquatic macrophytes become reestablished and nutrients in the sediments are released to the water column

  16. Thermal Efficiency for Each Zone of a Solar Pond

    Institute of Scientific and Technical Information of China (English)

    BEZ(I)R C(I)CEK Nalan; SAH(I)N SENCAN Arzu

    2011-01-01

    A salt gradient solar pond with a surface area of 3.5×3.5 m2 and a depth of 2m is built.Two collapsible covers are used to reduce thermal energy loss from the surface of the solar pond during the night and to increase the thermal efficiency of the pond solar energy harvesting during daytime.The covers can be rotated between 0 and 180° by a controlled electric motor and has insulation and reflection properties.The thermal efficiency for each solar pond zone is investigated theoretically and experimentally.A salt gradient solar pond (SGSP) can store a portion of solar radiation as thermal energy for longterm use.Long-term energy storage in a solar pond is important for many applications,i.e.greenhouse heating or heating in buildings.%A salt gradient solar pond with a surface area of 3.5×3.5 m2 and a depth of 2m is built. Two collapsible covers are used to reduce thermal energy loss from the surface of the solar pond during the night and to increase the thermal efficiency of the pond solar energy harvesting during daytime. The covers can be rotated between 0 and 180° by a controlled electric motor and has insulation and reflection properties. The thermal efficiency for each solar pond zone is investigated theoretically and experimentally.

  17. Development of shrimp in small ponds

    Directory of Open Access Journals (Sweden)

    Armando Adolfo Ortega Salas

    2014-06-01

    Full Text Available Development of white shrimp Litopenaeus vannamei in small ponds ( 6 m3 in fresh water (2-3‰ and seawater; ponds 3.66 x 1.65 x 1.0 m; availability of fresh water, sea water, aeration and drainage. Two cycles of three months each were made. The postlarvae were acclimated to seawater fresh water in four days. Four hundred postlarvas/m3 were seeded in freshwater pond and 500 in the pool of seawater. First, a culture of Daphnia magna in the freshwater pond, also appeared chyronomid larvae; Artemia cysts were seeded in sea water as a dietary supplement. The shrimp were fed Camaronina (25% protein at libitum, daily; is offered on a tray of food; the temperature ranged between 27 and 30° C, oxygen 4.26 ± 1.43 mg / L , pH between 7 and 8 . Detritus siphoned every third day. Water changes between 10 and 20% are often performed. The feed conversion rate (FCR was 1:1.3 . The shrimp were measured in length and weight to calculate weekly growth by Bertalanffy model. Survival in the first cycle was 95.8 , and 97.9% for the second cycle. In seawater parameters of the population of the first cycle were k = 0.0301, L ∞ = 322.16 and t0 = -0.8852, the second cycle of k = 0.0203, L ∞ = 294.42 and t0 = -5.3771. The biomass of 27 kg was obtained for the first cycle and 16 kg for the second cycle. Freshwater population parameters of the first cycle were k = 0.0957, L ∞ = 146.98 and t0 = - 0.93; in the second cycle of k = 0.0172 , L ∞ = 367.82 and t0 = - 4.60. The biomass of 26 kg was obtained for the first cycle and 16 kg for the second cycle. The results indicate a rapid growth during the first 10 weeks. In small ponds can be handled well aseptic conditions without disease problems, good crop was obtained.

  18. Site-specific health and safety plan 100-D Pond remediation project

    International Nuclear Information System (INIS)

    The 100-D Ponds are located north of the northern perimeter fence of the 100-D Area. The ponds were excavated in a preexisting basin that had been used for disposal of coal ash. There are two ponds, one used as a settling pond and the other a percolation pond. Liquid effluent from the 100-D process sewers was discharged to the ponds from 1977 through 1987; after 1987 the ponds received backwash and rinsate from the 100-D water treatment facilities. All discharges to the ponds ceased in June 1994, and the ponds were allowed to dry up

  19. The western pond turtle: Habitat and history. Final report

    International Nuclear Information System (INIS)

    The western pond turtle is known from many areas of Oregon. The majority of sightings and other records occur in the major drainages of the Klamath, Rogue, Umpqua, Willamette and Columbia River systems. A brief overview is presented of the evolution of the Willamette-Puget Sound hydrographic basin. A synopsis is also presented of the natural history of the western pond turtle, as well as, the status of this turtle in the Willamette drainage basin. The reproductive ecology and molecular genetics of the western pond turtle are discussed. Aquatic movements and overwintering of the western pond turtle are evaluated. The effect of introduced turtle species on the status of the western pond turtle was investigated in a central California Pond. Experiments were performed to determine if this turtle could be translocated as a mitigation strategy

  20. Rescuing Ecosystems from Extinction Cascades

    Science.gov (United States)

    Sahasrabudhe, Sagar; Motter, Adilson

    2010-03-01

    Food web perturbations stemming from climate change, overexploitation, invasive species, and natural disasters often cause an initial loss of species that results in a cascade of secondary extinctions. Using a predictive modeling framework, here we will present a systematic network-based approach to reduce the number of secondary extinctions. We will show that the extinction of one species can often be compensated by the concurrent removal of a second specific species, which is a counter-intuitive effect not previously tested in complex food webs. These compensatory perturbations frequently involve long-range interactions that are not a priori evident from local predator-prey relationships. Strikingly, in numerous cases even the early removal of a species that would eventually be extinct by the cascade is found to significantly reduce the number of cascading extinctions. Other nondestructive interventions based on partial removals and growth suppression and/or mortality increase are shown to sometimes prevent all secondary extinctions.

  1. Polishing ponds for post-treatment of digested sewage. Part 1: Flow-through ponds.

    Science.gov (United States)

    Cavalcanti, P F; van Haandel, A; Lettinga, G

    2001-01-01

    Polishing ponds are used to improve the quality of effluents from efficient anaerobic sewage treatment plants like UASB reactors, so that the final effluent quality becomes compatible with legal or desired standards. The residual organic material and suspended solids concentrations in the digested sewage are reduced, but often the main objective of polishing ponds is to improve the hygienic quality, measured by the concentration of two indicator organisms: helminth eggs and faecal coliforms (FC). The FC removal is normally the slowest process and for that reason becomes the main design criterion for a polishing pond. By contrast in conventional waste stabilisation pond (WSP) systems the organic material removal is the governing design parameter. The feasibility of operating a single polishing pond for the post-treatment of UASB effluent is shown in this paper and the final effluent quality as a function of the retention time is discussed. Even under the most adverse weather conditions (several weeks of rain) the population of algae remained stable and produced enough oxygen to maintain a predominantly aerobic environment. The final effluent TSS and BOD concentrations were not very low for retention times of less than 1 week, but this could be attributed to the presence of algae in the final effluent. Filtered effluent BOD and TSS concentrations were very low. For retention times of more than 1 week algae were efficiently removed from the liquid phase by the action of predators and algae flocculation and settling, so that a final effluent with a very low BOD and TSS concentrations was produced. To maximise the FC removal efficiency the polishing pond was constructed with the objective of approaching a plug flow regime. However, the observed efficiency was well below the expected value for all retention times, which was attributable to imperfections of the flow regime. From tracer studies it was established that the dispersion number was in the range of 0.14 to 0

  2. Geochemistry of the Upper Parana River floodplain. Study of the Garcas Pond and Patos Pond

    International Nuclear Information System (INIS)

    The aim of this study was to investigate the temporal evolution of the supply of chemical elements to the Upper Parana River floodplain and identify trends in the geochemistry of its drainage basin. The primary factor that regulates the supply of chemical elements of the Upper Parana River floodplain is the flood pulse, which can be magnified by the El Nino-Southern Oscillation. Garcas Pond is affected by agriculture, urbanization, discharge of industrial effluents and hydroelectric power production activities. Patos Pond is affected by sugarcane burning, gold mining, agriculture and urbanization. (author)

  3. Computer simulation model of salt-gradient solar ponds

    Energy Technology Data Exchange (ETDEWEB)

    Panahi, Z.

    1981-01-01

    The mass and energy transfer processes of salt-gradient solar pond were developed into a finite element of computer model. The system represented by the model can be: (1) a non-convective salt-gradient solar pond for which the energy transfer takes place by conduction through the brine and the round beneath the pond; (2) a stratified three-zone solar pond consisting of upper and lower convective zones and a non-convective gradient zone in between. The temperature of the upper and lower convective zones are predicted in terms of the net energy input to the zones. The energy fluxes at the pond surface include: reflected and absorbed solar radiation, evaporation energy loss, net long wave radiation loss to the atmosphere, advected energy of precipitation and inflow water, and convective heat loss at the surface. The model predicts the time dependent concentration, density, and temperature gradients in the pond. The program can operate with any time step of less than or equal to 24 hours, using either average daily or variables (with the time step) values of air temperature (calculated in the model using average, maximum and minimum values) and solar radiation data. The different cases that have been studied using the model are (1) the performance of a non-insulated salt-gradient solar pond with seepage of the brine and energy exchange through the ground below the pond; (2) the performance of an insulated salt-gradient solar pond with seepage of the brine and energy exchange through the ground below the pond; (2) the performance of an insulated salt-gradient and stratified three-zone solar pond. For stratified ponds comparisons on performance are made by changing the thickness of: (1) the upper convective zone, (2) the non-convective gradient zone, and (3) the lower convective (storage) zone.

  4. Transition in the fractal geometry of Arctic melt ponds

    OpenAIRE

    C. Hohenegger; B. Alali; Steffen, K. R.; D. K. Perovich; Golden, K. M.

    2012-01-01

    During the Arctic melt season, the sea ice surface undergoes a remarkable transformation from vast expanses of snow covered ice to complex mosaics of ice and melt ponds. Sea ice albedo, a key parameter in climate modeling, is determined by the complex evolution of melt pond configurations. In fact, ice–albedo feedback has played a major role in the recent declines of the summer Arctic sea ice pack. However, understanding melt pond evolution remains a significant challenge to improving climate...

  5. Transition in the fractal geometry of Arctic melt ponds

    OpenAIRE

    C. Hohenegger; B. Alali; Steffen, K. R.; D. K. Perovich; Golden, K. M.

    2012-01-01

    During the Arctic melt season, the sea ice surface undergoes a remarkable transformation from vast expanses of snow covered ice to complex mosaics of ice and melt ponds. Sea ice albedo, a key parameter in climate modeling, is determined by the complex evolution of melt pond configurations. In fact, ice-albedo feedback has played a major role in the recent declines of the summer Arctic sea ice pack. However, understanding melt pond evolution remains a significant challenge to improving climate...

  6. Monitoring, sizing and removal efficiency in stormwater ponds

    OpenAIRE

    Persson, Jesper; Pettersson, Thomas J.R

    2009-01-01

    Retention ponds and wetlands are frequently used in stormwater management to remove pollutants, reduce flow peaks and improve scenic views in parks and along roads. This study analyzes the correlation between long-term removal efficiency of pollutants (total suspended solids and heavy metals) and specific pond area (ratio between effective drainage area and surface area). For this purpose, all data on ponds in Sweden that have been monitored were collected and evaluated. The results show that...

  7. Nanowire terahertz quantum cascade lasers

    International Nuclear Information System (INIS)

    Quantum cascade lasers made of nanowire axial heterostructures are proposed. The dissipative quantum dynamics of their carriers is theoretically investigated using non-equilibrium Green functions. Their transport and gain properties are calculated for varying nanowire thickness, from the classical-wire regime to the quantum-wire regime. Our calculation shows that the lateral quantum confinement provided by the nanowires allows an increase of the maximum operation temperature and a strong reduction of the current density threshold compared to conventional terahertz quantum cascade lasers.

  8. Transition in the fractal geometry of Arctic melt ponds

    Directory of Open Access Journals (Sweden)

    C. Hohenegger

    2012-10-01

    Full Text Available During the Arctic melt season, the sea ice surface undergoes a remarkable transformation from vast expanses of snow covered ice to complex mosaics of ice and melt ponds. Sea ice albedo, a key parameter in climate modeling, is determined by the complex evolution of melt pond configurations. In fact, ice–albedo feedback has played a major role in the recent declines of the summer Arctic sea ice pack. However, understanding melt pond evolution remains a significant challenge to improving climate projections. By analyzing area–perimeter data from hundreds of thousands of melt ponds, we find here an unexpected separation of scales, where pond fractal dimension D transitions from 1 to 2 around a critical length scale of 100 m2 in area. Pond complexity increases rapidly through the transition as smaller ponds coalesce to form large connected regions, and reaches a maximum for ponds larger than 1000 m2, whose boundaries resemble space-filling curves, with D ≈ 2. These universal features of Arctic melt pond evolution are similar to phase transitions in statistical physics. The results impact sea ice albedo, the transmitted radiation fields under melting sea ice, the heat balance of sea ice and the upper ocean, and biological productivity such as under ice phytoplankton blooms.

  9. Study on technique for integrated heating of a solar pond

    Energy Technology Data Exchange (ETDEWEB)

    Cao Jinlong [Ke Yuan New Energy Tech. Development Co. Ltd., Weifang, SD (China); Lu Xiaoyan [English Dept. of Weifang Medical Univ., SD (China)

    2008-07-01

    The first example in China of an integrated heating system using a solar pond was constructed on the banks of Laizhou Bay of Weifang city, in Shandong province. Adopting heating systems for seawater solar ponds, shallow-styled solar ponds and conservatory-model solar ponds, the system solves the problem of how to overwinter warm seawater fish. The method of heating in the course of nursing young aquatic products provides a new technique for protected aquaculture using solar energy. This essay introduces the technical parameters and development of the system and analyzes the validity of the technique and its prospects for application. Several shortcomings are also discussed. (orig.)

  10. Avifauna of waste ponds ERDA Hanford Reservation, Benton County, Washington

    International Nuclear Information System (INIS)

    The presence of small ponds on the Hanford 200 Area plateau provides attractive habitats for birds. During a 29-month period, 126 bird species were observed utilizing these ponds, their associated vegetation, and air space. Waterfowls are the important agents of dispersal of radionuclides from waste ponds based on food habits, abundance, migratory habits, and importance as food in the diet of people. Abundance, long residence time, and food habits identify the American coot as the single most important species to be considered in the biological dispersal of radionuclides from waste ponds. (U.S.)

  11. Investigation of turbidity effect on exergetic performance of solar ponds

    International Nuclear Information System (INIS)

    Highlights: • A comprehensive experimental work on a turbidity of the solar pond. • Percentage transmission evaluation of the turbid and clean salty water of the zones. • Exergy analysis of the inner zones for turbid and clean salty water. • Turbidity effect on exergy efficiencies of the solar pond. • The thermal performance assessment by comparing the exergetic efficiencies of the solar pond. - Abstract: The present paper undertakes a study on the exergetic performance assessment of a solar pond and experimental investigation of turbidity effect on the system performance. There are various types of solar energy applications including solar ponds. One of significant parameters to consider in the assessment of solar pond performance is turbidity which is caused by dirty over time (e.g., insects, leaf, dust and wind bringing parts fall down). Thus, the turbidity in the salty water decreases solar energy transmission through the zones. In this study, the samples are taken from the three zones of the solar pond and analyzed using a spectrometer for three months. The transmission aspects of the solar pond are investigated under calm and turbidity currents to help distinguish the efficiencies. Furthermore, the maximum exergy efficiencies are found to be 28.40% for the calm case and 22.27% with turbidity effects for the month of August, respectively. As a result, it is confirmed that the solar pond performance is greatly affected by the turbidity effect

  12. Characteristics for two kinds of cascading events

    Science.gov (United States)

    Zou, Sheng-Rong; Gu, Ai-Hua; Liu, Ai-Fen; Xu, Xiu-Lian; Wang, Jian; He, Da-Ren

    2011-04-01

    Avalanche or cascade failure is ubiquitous. We first classify the cascading phenomena into two categories: the cascading disasters which result in large-scale functional failures and the cascading events that do not lead to disasters. We elucidate that two important factors, the increasing amount of events and the acceleration of event frequency, can induce the crossover from the cascading phenomenon to the cascading disaster. Through a simplified sandpile model and a heuristic logistic map, we demonstrate that the dependence of the event number on the observation time behaves as a power-law and as an exponential for these two different cascading events, respectively. The analytic derivations are found to be consistent with several empirical observations. Our present findings contribute to the understanding of the transition between different cascading events, providing a basis for the further understanding of the transitions among more general critical events.

  13. Cascade Support Vector Machines with Dimensionality Reduction

    Directory of Open Access Journals (Sweden)

    Oliver Kramer

    2015-01-01

    Full Text Available Cascade support vector machines have been introduced as extension of classic support vector machines that allow a fast training on large data sets. In this work, we combine cascade support vector machines with dimensionality reduction based preprocessing. The cascade principle allows fast learning based on the division of the training set into subsets and the union of cascade learning results based on support vectors in each cascade level. The combination with dimensionality reduction as preprocessing results in a significant speedup, often without loss of classifier accuracies, while considering the high-dimensional pendants of the low-dimensional support vectors in each new cascade level. We analyze and compare various instantiations of dimensionality reduction preprocessing and cascade SVMs with principal component analysis, locally linear embedding, and isometric mapping. The experimental analysis on various artificial and real-world benchmark problems includes various cascade specific parameters like intermediate training set sizes and dimensionalities.

  14. Comparison between field data and ultimate heat-sink cooling-pond and spray-pond models

    International Nuclear Information System (INIS)

    Two previously published reports, NUREG-0693 and NUREG-0733, presented models and methods by which ultimate heat sink cooling ponds and spray ponds used for safety-related water supplies in nuclear power plants could be analyzed for design-basis conditions of heat load and meteorology. These models were only partially verified with field data. The present report compares the NRC models to data collected for NRC by Battelle Pacific Northwest Laboratories on the performance of small geothermally heated ponds and spray ponds. These comparisons generally support the conclusion that the NRC models are useful tools in predicting ultimate heat sink performance

  15. Application of polymeric flocculant for enhancing settling of the pond ash particles and water drainage from hydraulically stowed pond ash

    Institute of Scientific and Technical Information of China (English)

    Mishra Devi Prasad; Das Samir Kumar

    2013-01-01

    Delayed settling of the ash particles and poor drainage of water from the pond ash are the major problems faced during the hydraulic stowing of pond ash.In this study the effect of polymeric flocculant on settling of the ash particles and drainage of water during pond ash stowing are investigated.In addition,the parameters,viz.drainage and absorption of water during pond ash stowing are quantified by stowing a mine goaf model with pond ash slurries of five different concentrations added with and without flocculant.The study revealed that addition of only 5 × 10-6 of Sodium Carboxymethyl Cellulose (Na-CMC)flocculant with the pond ash slurries during stowing offers best result in terms of quicker settling of the ash particles and enhanced water drainage from the hydraulically stowed pond ash.Besides,it resulted in drainage of more than 85% of the total water used in the initial 45 min of stowing.The improvement in drainage is caused due to coagulation and flocculation of the pond ash particles because of charge neutralization and particle-particle bridging.This study may provide a basis for estimating the drainage and absorption of water during the real pond ash stowing operation in underground mines.

  16. International experience in tailings pond remediation

    International Nuclear Information System (INIS)

    Tailings pond remediation is required primarily on mine closure. While mining is an ancient industry, requirement for mine facility remediation is a comparatively new development. Requirement for remediation has come about partly as a result of mans awareness of the environmental impacts of mining and his desire to minimize this, partly, as a result of the ever-increasing scale and production rates of tailings generation and the resulting increased environmental impacts and safety risks. The paper starts with a review of the evolution of mans intolerance of environmental impacts from tailings production and the assignment of liability to remediate such impacts. Many of the tailings ponds currently undergoing remediation were designed and constructed using methods and technology that would be considered inappropriate for new impoundments being designed and developed today. The paper reviews the history of tailings impoundment design and construction practice and the resulting inherent deficiencies that must be remediated. Current practices and future trends in tailings pond remediation are reviewed. The evolution of regulatory requirements is not only in terms of technical and safety criteria, but also in terms of financial and political risk. Perhaps the most substantive driver of risk management is today the requirement for corporate governance at mining company board level and oversight of new project development in the underdeveloped countries by the large financial institutions responsible for funding projects. Embarrassment in the public eye and punishment in the stock markets for poor environmental and safety performance is driving the need for efficient and effective risk management of potential impacts and the remediation to avoid these. A basis for practical risk management is described. (orig.)

  17. Oxygen and nitrogen dynamics in split ponds vs. conventional catfish production ponds

    Science.gov (United States)

    The Split Pond aquaculture system (SP) has captured the attention of catfish producers across the southern U.S. The SP represents a lower cost adaptation of Clemson University’s Partitioned Aquaculture System (PAS). The original PAS design relied on slowly rotating paddlewheels to move water throu...

  18. Comparison of phytoplankton communities in catfish split-pond aquaculture systems with conventional ponds.

    Science.gov (United States)

    There has been a growing interest and use of variations of partitioned aquaculture systems (PAS) in recent years by the southeastern United States of America farmed catfish industry. Split-pond systems, one type of PAS, are designed to better manage fish waste byproducts (e.g., ammonia) and dissolv...

  19. Azobenzene-functionalized cascade molecules

    DEFF Research Database (Denmark)

    Archut, A.; Vogtle, F.; De Cola, L.;

    1998-01-01

    Cascade molecules bearing up to 32 azobenzene groups in the periphery have been prepared from poly(propylene imine) dendrimers and N-hydroxysuccinimide esters. The dendritic azobenzene species show similar isomerization properties as the corresponding azobenzene monomers. The all-E azobenzene den...

  20. Applications of cascade multilevel inverters

    Institute of Scientific and Technical Information of China (English)

    彭方正; 钱照明

    2003-01-01

    Cascade multilevel inverters have been developed for electric utility applications. A cascade M-level inverter consists of (M-1)/2 H-bridges in which each bridge's dc voltage is supported by its own de ca-pacitor. The new inverter can : ( 1 ) generate almost sinusoidal waveform voltage while only switching one timeper fundamental cycle ; (2) dispense with multi-pulse inverters' transformers used in conventional utility in-terfaces and static var compensators; (3) enables direct parallel or series transformer-less connection to medium- and high-voltage power systems. In short, the cascade inverter is much more efficient and suitable for utility applications than traditional multi-pulse and pulse width modulation (PWM) inverters. The authors have experimentally demonstrated the superiority of the new inverter for power supply, (hybrid) electric vehicle (EV) motor drive, reactive power (var) and harmonic compensation. This paper summarizes the features,feasibility, and control schemes of the cascade inverter for utility applications including utility interface of renewable energy, voltage regulation, var compensation, and harmonic filtering in power systems. Analytical,simulated, and experimental results demonstrated the superiority of the new inverters.

  1. Applications of cascade multilevel inverters

    Institute of Scientific and Technical Information of China (English)

    彭方正; 钱照明

    2003-01-01

    Cascade multilevel inverters have been developed for electric utility applications. A cascade M-level inverter consists of (M-1)/2 H-bridges in which each bridge's dc voltage is supported by its own dc capacitor. The new inverter can: (1) generate almost sinusoidal waveform voltage while only switching one time per fundamental cycle; (2) dispense with multi-pulse inverters' transformers used in conventional utility interfaces and static var compensators; (3) enables direct parallel or series transformer-less connection to medium- and high-voltage power systems. In short, the cascade inverter is much more efficient and suitable for utility applications than traditional multi-pulse and pulse width modulation (PWM) inverters. The authors have experimentally demonstrated the superiority of the new inverter for power supply, (hybrid) electric vehicle (EV) motor drive, reactive power (var) and harmonic compensation. This paper summarizes the features, feasibility, and control schemes of the cascade inverter for utility applications including utility interface of renewable energy, voltage regulation, var compensation, and harmonic filtering in power systems. Analytical, simulated, and experimental results demonstrated the superiority of the new inverters.

  2. Multiplicity distributions in QCD cascades

    International Nuclear Information System (INIS)

    Multiplicity distributions for hadrons and for jets are studied in QCD parton cascades. The colour dipole formalism is used and earlier results in the double log approximation are generalized to include terms which are suppressed by colour factors or factors of ln s. The result is a set of coupled differential equations, together with appropriate boundary conditions

  3. Strangeness Production and Ultrarelativistic Cascades

    CERN Document Server

    Kahana, D E

    1998-01-01

    A two phase cascade, LUCIFER II, developed for the treatment of ultra high energy ion-ion collisions is applied to the production of strangeness at SPS energies $\\sqrt{s}=17-20$. This simulation is able to simultaneously describe both hard processes such as Drell-Yan and slower, soft processes such as the production of light mesons, including strange mesons, by separating the dynamics into two steps, a fast cascade involving only nucleons in the original colliding relativistic ions followed, after an appropriate delay, by multiscattering of the resulting excited baryons and mesons produced virtually in the first step. No energy loss can take place in the short time interval over which the first cascade takes place. The chief result is a reconciliation of the important Drell-Yan measurements with the apparent success of standard cascades to describe the nucleon stopping and meson production in heavy ion experiments at the CERN SPS. A byproduct, obtained here in preliminary calculations, is a description of str...

  4. 30 CFR 817.56 - Postmining rehabilitation of sedimentation ponds, diversions, impoundments, and treatment...

    Science.gov (United States)

    2010-07-01

    ... ponds, diversions, impoundments, and treatment facilities. 817.56 Section 817.56 Mineral Resources... Postmining rehabilitation of sedimentation ponds, diversions, impoundments, and treatment facilities. Before... removed and reclaimed, and that all permanent sedimentation ponds, diversions, impoundments, and...

  5. 30 CFR 816.56 - Postmining rehabilitation of sedimentation ponds, diversions, impoundments, and treatment...

    Science.gov (United States)

    2010-07-01

    ... ponds, diversions, impoundments, and treatment facilities. 816.56 Section 816.56 Mineral Resources... rehabilitation of sedimentation ponds, diversions, impoundments, and treatment facilities. Before abandoning a... and reclaimed, and that all permanent sedimentation ponds, diversions, impoundments, and...

  6. Phyllosphere mycobiota on garden ponds plants

    Directory of Open Access Journals (Sweden)

    Maria Kowalik

    2013-12-01

    Full Text Available Investigations were conducted on calamus, common cattail, soft rush, yellow iris and white water lily plants in twenty ponds in Malopolska and Podkarpacie Regions. Mycobiota existing in the phyllosphere caused discolouring and necroses of leaves and shoots. 88 species of mycobiota were identified and isolated from the diseased tissues. Dominant were Alternaria alternata, Epicoccum nigrum and Isaria farinosa. Fungi of genera: Aspergillus, Botrytis, Chaetomium, Cladosporium, Fusarium, Ilyonectria, Mortierella, Mucor, Penicillium, Phialophora, Phoma, Pleustomophora, Sordaria, Trichoderma and Umbelopsis were also numerous. The monophagous and the polyphagous were identified.

  7. Commercial pond fish culture using waste water

    OpenAIRE

    Okoye, F.C.; Ita, E.O.; Adeniji, H.A.

    1987-01-01

    Waste water from some National Electric Power Authority (NEPA) housing units in Nigeria was fed to a 0.4 ha pond which was stocked with 2,200 Sarotherodon galilaeus fingerlings with a mean weight of about 36.0gm and 1000 Cyprinus carpio fingerlings with a mean weight of 10gm. This yielded after 10 months, over 2300 kg of harvestable fish plus over 20,000 Sarotherodon galilaeus fingerlings. The growth rate of C. carpio was not very encouraging possibly because of the type of plankton that colo...

  8. Intranuclear cascade models lack dynamic flow

    OpenAIRE

    Molitoris, Joseph J.; Stöcker, Horst; Gustafsson, Hans-Ake; Cugnon, Joseph; L'Hote, Denis

    2006-01-01

    We study the recent claim that the intranuclear cascade model exhibits collective sidewards flow. 4000 intranuclear cascade simulations of the reaction Nb(400 MeV/nucleon)+Nb are performed employing bound and unbound versions of the Cugnon cascade. We show that instability of the target and projectile nuclei in the unbound cascade produces substantial spurious sidewards flow angles, for spectators as well as for participants. Once the nuclear binding is included, the peak of the flow angle di...

  9. Account of cascade formation depth during sputtering

    International Nuclear Information System (INIS)

    Cascade theory of sputtering is considered. It is suggested to take account of the fact that cascade in a solid forms at a certain depth. This results in decreasing a sputtered particle yield and in changing the form of angular distributions. Angular distributions of sputtered particles were calculated for plane and spherical potential barriers. It was demonstrated that account of cascade formation depth enabled to describe the experiment much better as compared to standard cascade theories. 9 refs.; 13 figs.; 2 tabs

  10. Examining Water Quality Variations of Tidal Pond System

    Science.gov (United States)

    Chui, T. F. M.; Cui, W.

    2014-12-01

    Brackish tidal shrimp ponds, traditionally referred to as gei wais, have been constructed along coastal areas in many parts of the world. The regular exchange of pond water with the surrounding coastal environment is important as it brings shrimp larvae and nutrients, etc. into and out of the pond. Such a water exchange can reduce the quality of the receiving waters; though there are opposing views recently because farming practices are becoming more sustainable while other sources of pollutions in the surroundings are increasing. This project monitors the water quality of a tidal shrimp pond and its receiving water at high temporal resolution. The pond is located within the wetland complex of Mai Po Nature Reserve in Hong Kong, China. Water quality parameters (i.e., dissolved oxygen, temperature, salinity, pH, water depth and chlorophyll) were recorded at 15-minute interval from December 2013 to March 2014 within the pond and also at its receiving water which is a water channel within a mangrove forest. Data reveals both daily and fortnightly fluctuations. Daily variations in mangrove correspond to both tidal flushing and insolation, whereas those within the pond correspond mainly to insolation. For example, dissolved oxygen in mangrove shows two peaks daily which correlate with tidal elevation, and that within the pond shows only one peak which correlates with sunlight. Dissolved oxygen within the pond also shows a fortnightly pattern that corresponds to the schedule of water exchange. Such high temporal resolution of monitoring reveals the two-way water quality influences between the pond and the mangrove. It sheds insights that can possibly lead to refinement of water exchange practice and water sampling schedule given the temporal variations of the water quality both inside and outside the pond. It thus enables us to take a step closer in adopting more sustainable farming practices despite increasing pollution in the surrounding areas.

  11. Experimental canopy removal enhances diversity of vernal pond amphibians.

    Science.gov (United States)

    Skelly, David K; Bolden, Susan R; Freidenburg, L Kealoha

    2014-03-01

    Vernal ponds are often treated as protected environments receiving special regulation and management. Within the landscapes where they are found, forest vegetation frequently dominates surrounding uplands and can grow to overtop and shade pond basins. Two bodies of research offer differing views of the role of forest canopy for vernal pond systems. Studies of landscape conversion suggest that removing forest overstory within uplands can cause local extinctions of amphibians by altering terrestrial habitat or hindering movement. Studies of canopy above pond basins imply an opposite relationship; encroachment of overstory vegetation can be associated with local extinctions potentially via changes in light, thermal, and food resource environments. Unresolved uncertainties about the role of forest canopy reveal significant gaps in our understanding of wetland species distributions and dynamics. Any misunderstanding of canopy influences is simultaneously important to managers because current practices emphasize promoting or conserving vegetation growth particularly within buffers immediately adjacent to ponds. We evaluated this apparent contradiction by conducting a landscape-scale, long-term experiment using 14 natural vernal ponds. Tree felling at six manipulated ponds was limited in spatial scope but was nevertheless effective in increasing water temperature. Compared with eight control ponds, manipulated ponds maintained more amphibian species during five years post-manipulation. There was little evidence that any species was negatively influenced, and the reproductive effort of species for which we estimated egg inputs maintained pretreatment population densities in manipulated compared with control ponds. Overall, our experiment shows that a carefully circumscribed reduction of overhead forest canopy can enhance the capacity of vernal ponds to support wildlife diversity and suggests a scale dependence of canopy influences on amphibians. These findings have

  12. Analysis of boson cascade laser characteristics

    Science.gov (United States)

    Ivanov, K. A.; Kaliteevskaya, N. A.; Gubaidullin, A. R.; Kaliteevski, M. A.

    2015-11-01

    The dependence of the level population on pumping in a boson cascade laser has been theoretically studied. Analytical expressions for the population of various cascade levels and the terahertz mode below and above the pumping threshold are obtained. Formulas for the pumping threshold and external quantum efficiency of the boson cascade laser are derived.

  13. Epitaxial growth of YBa2Cu3O7-δ on Ni89V11 non-magnetic biaxially textured substrate using NiO as buffer layer

    International Nuclear Information System (INIS)

    The superconducting YBa2Cu3O7-δ/CeO2/NiO multilayer structure was grown in situ by pulsed-laser deposition on biaxially textured Ni89V11 non-magnetic alloy. The role of vanadium is to decrease the Curie temperature of Ni and to favour the formation of oriented NiO. The (00l)NiO buffer layer has been formed by the controlled oxidation of the Ni-V substrate under 10 mTorr oxygen pressure and at 700 deg. C. The critical current density of 0.6 MA cm-2, at 77 K and zero magnetic field, was obtained for 0.7 μm thick YBa2Cu3O7-δ films. (author)

  14. Box Model of a Series of Salt Ponds, as Applied to the Alviso Salt Pond Complex, South San Francisco Bay, California

    Science.gov (United States)

    Lionberger, Megan A.; Schoellhamer, David H.; Shellenbarger, Gregory; Orlando, James L.; Ganju, Neil K.

    2007-01-01

    This report documents the development and application of a box model to simulate water level, salinity, and temperature of the Alviso Salt Pond Complex in South San Francisco Bay. These ponds were purchased for restoration in 2003 and currently are managed by the U.S. Fish and Wildlife Service to maintain existing wildlife habitat and prevent a build up of salt during the development of a long-term restoration plan. The model was developed for the purpose of aiding pond managers during the current interim management period to achieve these goals. A previously developed box model of a salt pond, SPOOM, which calculates daily pond volume and salinity, was reconfigured to simulate multiple connected ponds and a temperature subroutine was added. The updated model simulates rainfall, evaporation, water flowing between the ponds and the adjacent tidal slough network, and water flowing from one pond to the next by gravity and pumps. Theoretical and measured relations between discharge and corresponding differences in water level are used to simulate most flows between ponds and between ponds and sloughs. The principle of conservation of mass is used to calculate daily pond volume and salinity. The model configuration includes management actions specified in the Interim Stewardship Plan for the ponds. The temperature subroutine calculates hourly net heat transfer to or from a pond resulting in a rise or drop in pond temperature and daily average, minimum, and maximum pond temperatures are recorded. Simulated temperature was compared with hourly measured data from pond 3 of the Napa?Sonoma Salt Pond Complex and monthly measured data from pond A14 of the Alviso Salt-Pond Complex. Comparison showed good agreement of measured and simulated pond temperature on the daily and monthly time scales.

  15. Surface Sediments in Precooler Ponds 2, 4, and 5: March 2000

    Energy Technology Data Exchange (ETDEWEB)

    Dunn, D.L.

    2001-01-29

    Pond 2, Pond 4, and Pond 5 are inactive reactor cooling impoundments built in 1961 on the R-Reactor Effluent System in the east-central portion of the Department of Energy's Savannah River Site in Aiken, South Carolina. These precooler ponds are part of the Par Pond cooling water system and are considered part of the Par Pond operable unit. The intent was not to characterize the ponds, but to identify the maximum levels of contamination that could be exposed if the ponds are drained to remove the danger of dam failure.

  16. Delayed feeding of channel catfish fry stocked in ponds

    Science.gov (United States)

    We compared production variables between channel catfish, Ictalurus punctatus, nursery ponds fed according to industry standards, that is feeding immediately at stocking, to an alternative practice of delaying feeding for 6 wk after stocking in an effort to utilize natural pond productivity and redu...

  17. Wind Effects on Retention Time in Highway Ponds

    DEFF Research Database (Denmark)

    Bentzen, Thomas Ruby; Larsen, Torben; Rasmussen, Michael R.

    2007-01-01

    The paper presents results from an experimental and numerical study of wind-induced flows and transportation patterns in highway wet detention ponds. The study presented here is part of a general investigation on road runoff and pollution in respect to wet detention ponds. The objective is to eva...

  18. STORMWATER TREATMENT: WET/DRY PONDS VS. CONSTRUCTED WETLANDS

    Science.gov (United States)

    Extant data were used to assess the relative effectiveness of ponds vs. wetland-type BMPs. Compared to wet ponds, wetlands tended toward higher constituent concentrations in effluent, were inefficient at nitrogen removal, and appeared to preferentially retain phosphorous. These d...

  19. Origin and flatness of ponds on asteroid 433 Eros

    Science.gov (United States)

    Roberts, James H.; Kahn, Eliezer G.; Barnouin, Olivier S.; Ernst, Carolyn M.; Prockter, Louise M.; Gaskell, Robert W.

    2014-10-01

    NEAR-Shoemaker Multi-Spectral Imager data reveal several hundred "ponds" on 433 Eros: smooth deposits that sharply embay the bounding depressions in which they lie, and whose spectra appear blue relative to that of the surrounding terrain. We investigate the topography of these ponds on Eros using a new shape model derived from stereophotoclinometric analysis, and validated against altimetry from the NEAR Laser Rangefinder, to constrain the mode of pond formation from three existing models. We update the locations of 55 pond candidates identified in images registered to the new shape model. We classify the flatness of these features according to the behavior of the first and second derivatives of the topography. We find that less than half of pond candidates have clearly flat floors. Based on the pond topography, we favor an external origin for the ponds' deposits. We suggest that fine dust may be transported into bounding depressions by electrostatic levitation, but may adhere to slopes, and that seismic shaking may not be sufficient to bring the deposits to an equipotential surface. Disaggregation of a central boulder should result in an obvious break in slope, such a variation is only observed in roughly half the pond candidates.

  20. Relationship Between Accumulation and Influx of Pollutants in Highway Ponds

    DEFF Research Database (Denmark)

    Bentzen, Thomas Ruby; Larsen, Torben; Rasmussen, Michael R.

    The paper discusses the long term mass balance of pollutants in highway ponds. The accumulations of five polycyclic aromatic hydrocarbons (PAHs) and six heavy metals have been measured in eight Danish detention ponds, which receive runoff from highways only. For each pollutant the accumulation has...

  1. Cannibalism in single-batch hybrid catfish production ponds

    Science.gov (United States)

    Hybrid catfish are more efficiently harvested by seining than are Channel Catfish. Due to that, and their faster growth, hybrids are typically produced in “single-batch” production systems, either in intensively-aerated commercial ponds or in split-pond systems. In either production system, hybrids...

  2. Gauging the Health of New England's Lakes and Ponds

    Science.gov (United States)

    The New England Lakes and Ponds Project provides a consistent and first time comprehensive assessment of the ecological and water quality condition of lakes and ponds across the New England region. The project is being conducted by EPA along with the New England Interstate Water...

  3. Eutrophic urban ponds suffer from cyanobacterial blooms: Dutch examples

    NARCIS (Netherlands)

    Waaijenberg, G.W.A.M.; Faassen, E.J.; Lurling, M.

    2014-01-01

    Ponds play an important role in urban areas. However, cyanobacterial blooms counteract the societal need for a good water quality and pose serious health risks for citizens and pets. To provide insight into the extent and possible causes of cyanobacterial problems in urban ponds, we conducted a surv

  4. Factors Influencing Fecal Contamination in Pond of Bangladesh

    Science.gov (United States)

    Knappett, P. S.; Escamilla, V.; Layton, A.; McKay, L. D.; Emch, M.; Mailloux, B. J.; Williams, D. E.; Huq, M. R.; Alam, M.; Farhana, L.; Ferguson, A. S.; Sayler, G. S.; Ahmed, K.; Serre, M. L.; Akita, Y.; Yunus, M.; van Geen, A.

    2010-12-01

    Occurrence of diarrheal disease in villages in rural Bangladesh remains relatively common, even though many households have switched to tubewell water for drinking and cooking. One factor contributing to this may be exposure to fecal contamination in ponds, which are often used for bathing and fishing. The objective of this study is to determine the dominant sources of fecal pollution in typical ponds and to explore the relationship between local population, latrine density, latrine quality and concentrations of fecal bacteria and pathogens in pond water. Forty-three ponds were sampled and analyzed for E. coli using culture-based methods and for E. coli, Bacteroides and adenovirus using quantitative PCR. Population and sanitation infrastructure were surveyed and compared to levels of pond fecal contamination. Molecular fecal source tracking using Bacteroides, determined that humans were the dominant source of fecal contamination in 79% of the ponds. Ponds directly receiving latrine effluent had the highest concentrations of fecal indicator bacteria. Concentrations of fecal indicator bacteria correlated with population surveyed within a distance of 30-70 m (pcattle. Since the majority of fecal pollution is from humans, use of pond water could help explain the persistence of diarrheal disease in rural Bangladesh.

  5. Amphibian Oasis: Designing and Building a Schoolyard Pond.

    Science.gov (United States)

    Gosselin, Heather; Johnson, Bob

    1996-01-01

    Building a pond in a schoolyard is a rewarding way to help boost local populations of amphibians, to increase the natural value of school grounds, and to serve as a locale for observing the life cycles of plants, invertebrates, and amphibians. This article outlines important considerations in designing and building a pond from siting through…

  6. 2101-M Pond hydrogeologic characterization report

    Energy Technology Data Exchange (ETDEWEB)

    Chamness, M.A.; Luttrell, S.P.; Bates, D.J.; Martin, W.J.

    1990-09-01

    This report documents information collected by the Pacific Northwest Laboratory {sup (a)} at the request of Westinghouse Hanford Company. Presented in this report is the interpretation of the hydrogeologic environment at the 2101-M Pond, located in the 200-East Area of the Hanford Site. This information and its accompanying interpretation were derived from sampling and testing activities associated with the installation of four ground-water monitoring wells, in addition to data gathered from several previously existing wells. The new monitoring wells were installed as part of a groundwater monitoring program initiated in 1988. The four new monitoring wells were installed around the 2101-M Pond between May 23 and August 27, 1988. Geologic sampling, aquifer testing, and initial ground-water sampling were performed during the installation of these wells. Laboratory analyses of the sediment samples for particle size, calcium carbonate content, and selected natural and contaminant constituents were performed. A full year of quarterly ground-water sampling and the first statistical analysis of background and downgradient data have also been performed. 112 refs., 49 figs., 18 tabs.

  7. Phytoremediation efficiency of Eichhornia crassipes in fly ash pond.

    Science.gov (United States)

    Pandey, Vimal Chandra

    2016-05-01

    The present study was focused on field research to examine the phytoremediation potential of naturally grown Eichhornia crassipes in fly ash (FA) pond. Field results indicate the efficiency of E. crassipes for remediation of heavy metals from FA pond. The bioconcentration factor trend was Cr (3.75) > Cu (2.62) > Cd (1.05), and Cu (1.35) in root and stem, respectively. The survival and abundance growth of E. crassipes in the circumstance of heavy metal enriched FA pond is another highlight of the present research that reveals its toxitolerant characteristics. Thus, this lesson on phytoremediation proved that E. crassipes is a potential accumulator of Cu, Cr, and Cd from FA ponds and is a promising species for FA pond's remediation globally. PMID:26595413

  8. Simple intervention to reduce mosquito breeding in waste stabilisation ponds

    DEFF Research Database (Denmark)

    Ensink, Jeroen H J; Mukhtar, Muhammad; van der Hoek, Wim;

    2007-01-01

    Waste stabilisation ponds (WSP) are the preferred method for treatment of urban wastewater in low-income countries but, especially in arid regions, the pond systems can be important breeding sites for mosquitoes of medical importance. In a WSP system in Faisalabad, Pakistan, we assessed the impact...... of simple environmental interventions on mosquito occurrence and abundance. Reducing the amount of floating matter in the ponds, eliminating emergent vegetation and repairing cracks in the cement structure reduced the number of mosquito-positive samples in the intervention ponds to almost zero......, whereas the control ponds had a significant number of positive samples. This suggests that a combination of simple low-cost interventions is a feasible environmental management strategy for vector control in WSP systems that are located in areas where medically important mosquitoes may breed in the...

  9. Electromagnetically induced transparency and dark fluorescence in a cascade three-level Lithium molecule

    CERN Document Server

    Qi, J; Qi, Jianbing

    2005-01-01

    We observed electromagnetically induced transparency (EIT) and dark fluorescence in a cascade three-level diatomic Lithium system using Optical-Optical Double Resonance (OODR) spectroscopy. When a strong coupling laser couples the intermediate state $A^{1}\\Sigma^{+}_{u}(v=13, J=14)$ to the upper state $G^{1}\\Pi_{g}(v=11, J=14)$ of $^7Li_2$, the fluorescence from both $A^{1}\\Sigma^{+}_{u}$ and $G^{1}\\Pi_{g}$ states was drastically reduced as the weak probe laser was tuned through the resonance transition between the ground state $X^{1}\\Sigma^{+}_{g}(v=4, J=15)$ and the excited state $A^{1}\\Sigma^{+}_{u}(v=13, J=14)$. The strong coupling laser makes an optically thick medium transparent for the probe transition. In addition, The fact that fluorescence from the upper state $G^{1}\\Pi_{g}(v=11, J=14)$ was also dark when both lasers were tuned at resonance implies that the molecules were trapped in the ground state. We used density matrix methods to simulate the response of an open molecular three-level system to t...

  10. Heavy metal composition in stormwater and retention in ponds dependent on pond age, design and catchment type

    DEFF Research Database (Denmark)

    Egemose, Sara; Sønderup, Melanie J.; Grudinina, Anna;

    2015-01-01

    Heavy metals have toxic effects on flora and fauna in the aquatic environments and are of great concern in stormwater. Heavy metal runoff was studied in 37 stormwater ponds in Denmark with varying heavy metal load, catchment type and pond design. The studied metals were Cu, Cr, Cd, Pb, Ni and Zn....

  11. Internuclear cascade in high energy collisions

    International Nuclear Information System (INIS)

    The experimental analysis of the process of cascading in the target fragmentation region (TFR) is performed on the basis of the available experimental methods and data and the existing phenomenological models. The effect is studied separately for the deuteron and for the heavy nuclei. The following subjects are discussed: the experimental evidence for the existence of cascading phenomenon in TFR, the effective cascade cross section, the fraction of cascade interactions, multiplicity of particles produced through cascading and their rapidity distributions, the dependence of cascading on energy and on the type of projectile as well as on the size of the nucleus, the comparison with the phenomenological models and with other proposed mechanisms of particle production in TFR. The possibility of determining the hadronization time (formation time) through the study of the cascading process in TFR is pointed out. (author). 90 refs

  12. Bankruptcy cascades in interbank markets.

    Directory of Open Access Journals (Sweden)

    Gabriele Tedeschi

    Full Text Available We study a credit network and, in particular, an interbank system with an agent-based model. To understand the relationship between business cycles and cascades of bankruptcies, we model a three-sector economy with goods, credit and interbank market. In the interbank market, the participating banks share the risk of bad debits, which may potentially spread a bank's liquidity problems through the network of banks. Our agent-based model sheds light on the correlation between bankruptcy cascades and the endogenous economic cycle of booms and recessions. It also demonstrates the serious trade-off between, on the one hand, reducing risks of individual banks by sharing them and, on the other hand, creating systemic risks through credit-related interlinkages of banks. As a result of our study, the dynamics underlying the meltdown of financial markets in 2008 becomes much better understandable.

  13. Injectorless quantum-cascade lasers

    International Nuclear Information System (INIS)

    An 'injectorless' quantum-cascade (QC) laser is presented. The requirement of using injector regions to transport electrons from the lower laser level and other low-lying energy levels of one active region to the upper laser level of the next electron-downstream active region was eliminated by using an appropriately designed double-quantum-well 'chirped' superlattice active region. The major advantage of the 'injectorless' QC laser is the close packing of the active regions and the concomitant large optical confinement factor. Using a cascade of 75 consecutive active regions, designed for emission at λ=11.5μm, a pulsed peak output power of 270 mW is achieved at 7 K and approximately 10 mW at the maximum operating temperature of 195 K. [copyright] 2001 American Institute of Physics

  14. Bankruptcy Cascades in Interbank Markets

    Science.gov (United States)

    Tedeschi, Gabriele; Mazloumian, Amin; Gallegati, Mauro; Helbing, Dirk

    2012-01-01

    We study a credit network and, in particular, an interbank system with an agent-based model. To understand the relationship between business cycles and cascades of bankruptcies, we model a three-sector economy with goods, credit and interbank market. In the interbank market, the participating banks share the risk of bad debits, which may potentially spread a bank’s liquidity problems through the network of banks. Our agent-based model sheds light on the correlation between bankruptcy cascades and the endogenous economic cycle of booms and recessions. It also demonstrates the serious trade-off between, on the one hand, reducing risks of individual banks by sharing them and, on the other hand, creating systemic risks through credit-related interlinkages of banks. As a result of our study, the dynamics underlying the meltdown of financial markets in 2008 becomes much better understandable. PMID:23300760

  15. Lens Coupled Quantum Cascade Laser

    Science.gov (United States)

    Hu, Qing (Inventor); Lee, Alan Wei Min (Inventor)

    2013-01-01

    Terahertz quantum cascade (QC) devices are disclosed that can operate, e.g., in a range of about 1 THz to about 10 THz. In some embodiments, QC lasers are disclosed in which an optical element (e.g., a lens) is coupled to an output facet of the laser's active region to enhance coupling of the lasing radiation from the active region to an external environment. In other embodiments, terahertz amplifier and tunable terahertz QC lasers are disclosed.

  16. Results of submerged sediment core sampling and analysis on Par Pond, Pond C, and L Lake: July 1995

    International Nuclear Information System (INIS)

    Sediment cores from shallow and deep water locations in Par Pond, Pond C, and L Lake were collected and analyzed in 1995 for radioactive and nonradioactive constituents. This core analysis was conducted to develop a defensible characterization of contaminants found in the sediments of Par Pond, Pond C, and L Lake. Mercury was the only nonradiological constituent with a nonestimated quantity that was detected above the U.S Environmental Protection Agency Region IV potential contaminants of concern screening criteria. It was detected at a depth of 0.3--0.6 meters (1.0--2.0 feet) at one location in L Lake. Cesium-137, promethium-146, plutonium-238, and zirconium-95 had significantly higher concentrations in Par Pond sediments than in sediments from the reference sites. Cobalt-60, cesium-137, plutonium-238, plutonium-239/240, and strontium-90 had significantly higher concentrations in L-Lake sediments than sediments from the reference sites

  17. Par Pond phytoplankton in association with refilling of the pond: Final Report for sampling from February 1995 -- September 1996

    International Nuclear Information System (INIS)

    This report describes the results of phytoplankton analyses from Par Pond samples collected between February 1995 and September 1996. The principal objective of the study was to determine the effect of refilling of Par Pond following repair of the dam on the phytoplankton community. Algal blooms are often responsible for fish kills and other detrimental effects in ponds and lakes, and it was postulated that decaying vegetation from formerly exposed sediments might trigger algal blooms that could result in fish kills in Par Pond following the refill. Sporadic algal blooms involving blue-green algae were detected, especially during the summer of 1996. However, the data derived from the study demonstrates that overall, the refilling effort caused no significant negative impact to the pond attributable to phytoplankton dynamics

  18. Maintenance strategy for a salt gradient solar pond coupled with an evaporation pond

    Energy Technology Data Exchange (ETDEWEB)

    Agha, K.R.; Aburghres, S.M.; Ramadan, A.M. [Center for Solar Energy Studies, Tripoli (Libya)

    2000-07-01

    In this paper, all the results presented were predicted for the first three years of operation. The daily variations of brine concentration in the Evaporation Pond (EP) of Tajouras Experimental Solar Pond (TESP) and those based on different designs were predicted and discussed under different scenarios. The quantities of brine provided by the evaporation pond and that required by SGSP were predicted for both cases of surface water flushing (fresh water and seawater) under the different design conditions. The quantities of salt that can be contributed by (EP) were predicted to be in the range of 20% to 40% during the first year and 45% to 95% during the third year depending on the design selected. Comparing the percentage of salt provided for different designs, it can be clearly seen that the Autumn design presents a favorable condition. It provides a reasonable percentage reaching 79% in the case of fresh water surface flushing and 93% in the case of seawater surface flushing. Under the prevailing weather conditions of Tripoli, the results have shown that in addition to the higher flushing quantity required during the Summer, flushing is needed more frequent. It was predicted that the number of flushing varies between five times per month during the summer to two or three times per month during winter. Also, the study predicted that the quantity of seawater surface flushing is bigger than that of fresh water. (au)

  19. Design methodology for a salt gradient solar pond coupled with an evaporation pond

    Energy Technology Data Exchange (ETDEWEB)

    Agha, K.R.; Ramadan, A.M. [Center for Solar Energy Studies, Tripoli (Libya); Abughres, S.M. [Center for Solar Energy Studies, Tripoli (Libya); Faculty of Engineering, Tripoli (Libya). Dept. of Mechanical and Industrial Engineering

    2002-05-01

    This paper presents the results of a simple mathematical model for predicting the ratio of the evaporation pond (EP) area to that of a Salt Gradient Solar Pond (SGSP) area. The EP idea provides a very attractive method of salt recycling by evaporation, especially in areas of high rates of evaporation and low rates of rain as it is the case for North Africa. The model is applied for two types of surface water flushing (fresh water and seawater) under the prevailing conditions of Tripoli-Libya (Lat.=32.68{sup o}N) and for measured evaporation rates. Under the summer conditions and for the case of surface flushing by fresh water, the area ratio was estimated at about 0.17. While for the case of using seawater this ratio increases enormously to about 14.4. The time required for the salt concentration to increase from seawater concentration to a high concentrated brine, which can be injected at the bottom of the solar pond, is also presented. It was estimated that the time required to increase the salt concentration from 3.5 to 35% is about 120 to 250 days during the summer months and about 200 to 220 days during the winter months. (author)

  20. Long wavelength quantum cascade lasers

    International Nuclear Information System (INIS)

    The aim of this work is the extension of the concept of quantum cascade lasers towards longer wavelengths and the exploration of quantum cascade emission in the terahertz frequency regime. The first step is the realization of quantum cascade lasers based on GaAs/AlGaAs chirped superlattice active regions with photon energies above the longitudinal optical (LO-) phonon energy. These lasers push the long wavelength limit of GaAs-based quantum cascade lasers (previously at 13) to 23 micrometers. The 23-micrometer device is the first GaAs based quantum cascade laser with a metal surface plasmon waveguide. This waveguide scheme allows a reduction of the thickness of the epitaxially grown layer system and is therefore appropriate for long wavelength lasers. The measured threshold current densities reflect the differences in intersubband lifetimes and waveguide losses close to the LO-phonon energy. The major part of this thesis is devoted to the terahertz regime, i.e. the photon energy range below the LO-phonon energy. The intersubband scattering rate is no longer governed by LO-phonon emission from electrons at zero in-plane momentum, but disorder related scattering and electron-electron scattering come into play. Terahertz quantum cascade structures are designed, fabricated, and experimentally examined. Narrow linewidth (1.3 millielectronvolts) spontaneous emission is detected at a photon energy of 17.3 millielectronvolts (λ = 72 micrometers). To achieve population inversion the intersubband scattering rates have to be carefully engineered. Three strategies to manipulate the non-radiative rate are demonstrated: (1) Magnetic field quantization of the electronic motion reduces non-radiative scattering. Magneto-intersubband oscillations caused by inter-Landau-level transitions allow to determine the optical transition energy independently of the emission. (2) A reduction of the spatial overlap of initial and final subband by a barrier in an interwell transition causes a

  1. Observational bias and the apparent distribution of ponds on Eros

    Science.gov (United States)

    Roberts, James H.; Barnouin, Olivier S.; Kahn, Eliezer G.; Prockter, Louise M.

    2014-10-01

    Over 300 “ponds” have been identified on 433 Eros: smooth deposits that sharply embay the bounding depressions in which they lie. The known ponds are largely concentrated near the equator at the ends of the long axis of the asteroid. Here, we examine the pixel scale of images available at the pond locations, and compare the observed distribution of ponds on Eros to that of the image pixel scale. We find that the majority (60%) of ponds are found in the regions covered by images with pixel scales less than 2 m/px, a total of only 13% of the surface area. The correlation between pond density and image pixel scale suggests a significant observational bias in the identification of small ponds. These findings suggest that the distribution of ponds on Eros may not be as clear-cut as previously reported, and that it may be best not to use this distribution to assess existing models regarding their formation of these landforms.

  2. Environmental selection of planktonic methanogens in permafrost thaw ponds

    Science.gov (United States)

    Crevecoeur, Sophie; Vincent, Warwick F.; Lovejoy, Connie

    2016-08-01

    The warming and thermal erosion of ice-containing permafrost results in thaw ponds that are strong emitters of methane to the atmosphere. Here we examined methanogens and other Archaea, in two types of thaw ponds that are formed by the collapse of either permafrost peat mounds (palsas) or mineral soil mounds (lithalsas) in subarctic Quebec, Canada. Using high-throughput sequencing of a hypervariable region of 16S rRNA, we determined the taxonomic structure and diversity of archaeal communities in near-bottom water samples, and analyzed the mcrA gene transcripts from two sites. The ponds at all sites were well stratified, with hypoxic or anoxic bottom waters. Their archaeal communities were dominated by Euryarchaeota, specifically taxa in the methanogenic orders Methanomicrobiales and Methanosarcinales, indicating a potentially active community of planktonic methanogens. The order Methanomicrobiales accounted for most of the mcrA transcripts in the two ponds. The Archaeal communities differed significantly between the lithalsa and palsa ponds, with higher alpha diversity in the organic-rich palsa ponds, and pronounced differences in community structure. These results indicate the widespread occurrence of planktonic, methane-producing Archaea in thaw ponds, with environmental selection of taxa according to permafrost landscape type.

  3. Environmental selection of planktonic methanogens in permafrost thaw ponds.

    Science.gov (United States)

    Crevecoeur, Sophie; Vincent, Warwick F; Lovejoy, Connie

    2016-01-01

    The warming and thermal erosion of ice-containing permafrost results in thaw ponds that are strong emitters of methane to the atmosphere. Here we examined methanogens and other Archaea, in two types of thaw ponds that are formed by the collapse of either permafrost peat mounds (palsas) or mineral soil mounds (lithalsas) in subarctic Quebec, Canada. Using high-throughput sequencing of a hypervariable region of 16S rRNA, we determined the taxonomic structure and diversity of archaeal communities in near-bottom water samples, and analyzed the mcrA gene transcripts from two sites. The ponds at all sites were well stratified, with hypoxic or anoxic bottom waters. Their archaeal communities were dominated by Euryarchaeota, specifically taxa in the methanogenic orders Methanomicrobiales and Methanosarcinales, indicating a potentially active community of planktonic methanogens. The order Methanomicrobiales accounted for most of the mcrA transcripts in the two ponds. The Archaeal communities differed significantly between the lithalsa and palsa ponds, with higher alpha diversity in the organic-rich palsa ponds, and pronounced differences in community structure. These results indicate the widespread occurrence of planktonic, methane-producing Archaea in thaw ponds, with environmental selection of taxa according to permafrost landscape type. PMID:27501855

  4. Estimation of soil nutrients in L.vannamei culture ponds

    Directory of Open Access Journals (Sweden)

    Gunalan B

    2012-11-01

    Full Text Available Pond soil plays an important role in regulating the concentration of nutrients in the pond water. Shrimps normally live on or near the bottom, are exposed to conditions on the pond bottom. The present study was attempted to study the soil nutrients in the L.vannamei culture ponds. In the present study total carbon, total nitrogen and calcium were increasing considerably in almost all the ponds of Tamilnadu. The increment of total carbon was maximum in the ponds at Pattukottai and minimum in Marakanam. Similarly the increment of total nitrogen was maximum in Tranquebar and minimum in Parangipettai. Calcium was increased maximum in Marakanam and minimum in Tranquebar. However, boron, cadmium, cobalt, chromium, copper, iron, magnesium, manganese, nickel, lead, zinc showed decreasing trend when compared to beginning and end of the culture. The total carbon was increased maximum in the ponds of Orissa and it was minimum in Bhimavaram. Total nitrogen was increased maximum in Bhimavaram and minimum was in Gudur. Calcium was maximum in Gudur and minimum in Orissa. Other nutrients followed similar trend as in Tamilnadu. The present study strongly recommends the shrimp farmer to concentrate In every culture likely to enhance the bottom soil by adding some extra nutrient to the soil.

  5. Energy cascades in the upper ocean

    Institute of Scientific and Technical Information of China (English)

    Ray Q.Lin; Scott Chubb

    2006-01-01

    Wave-wave interactions cause energy cascades. These are the most important processes in the upper ocean because they govern wave-growth and dissipation. Through indirect cascades, wave energy is transferred from higher frequencies to lower frequencies, leading to wave growth. In direct cascades, energy is transferred from lower frequencies to the higher frequencies, which causes waves to break, and dissipation of wave energy. However, the evolution and origin of energy cascade processes are still not fully understood. In particular, for example, results from a recent theory (Kalmykov, 1998) suggest that the class I wave-wave interactions (defined by situations involving 4-, 6-, 8-, etc, even numbers of resonantly interacting waves) cause indirect cascades, and Class II wave-wave interactions (involving, 5-, 7-, 9-, etc, .., odd numbers of waves) cause direct cascades. In contrast to this theory, our model results indicate the 4-wave interactions can cause significant transfer of wave energy through both direct and indirect cascades. In most situations, 4-wave interactions provide the major source of energy transfer for both direct cascades and indirect cascades, except when the wave steepness is larger than 0.28. Our model results agree well with wave measurements, obtained using field buoy data (for example, Lin and Lin, 2002). In particular, in these observations, asymmetrical wave-wave interactions were studied. They found that direct and indirect cascades both are mainly due to the 4-wave interactions when wave steepness is less than 0.3.

  6. GROWING NIPA PALM FOR RESTORATION OF ABANDONED SHRIMP PONDS

    Institute of Scientific and Technical Information of China (English)

    Noparat Bamroongrugsa; Chorthip Purintavarakul

    2006-01-01

    Rapid increase in the production of marine shrimps in the coastal zone has resulted in large - scale conversion of mangrove forests to shrimp ponds. Productions of the shrimps in some regions have been unstable. Consequently, a number of ponds are left idle. Restoring environmental conditions within the pond site by planting a suitable mangrove species considered an option. The experiment herein was carried out to explore the effect of planting methods on growth of Nipa palm in abandoned shrimp ponds in the Southern Thailand. Economically, coastal villagers in this area earn their income from the palm in several ways, the most importantly in Nipa sugar production. Most seedlings were planted on top of furrows were constructed in the pond to avoid flooding, except for some seedlings which were planted in the pond base where additional pond sludge were slightly filled up to compare their growth rates. The results showed that planting seedlings with attached rhizomes had the best growth rate and without seedling death at 14 months after planting. At this stage, however, the height of seedlings grown from the fallen fruits was similar to those growth from bare rooted seedlings (70 cm tall). Also, seedling mortality was not observed when growth from fallen fruits whereas about6% mortality was experienced by the bare rooted ones. Among the bare rooted seedling treatments, however no significant differences in growth rates were found when applying the soil with chemical fertilizers or farm manure or liming with CaCO3. In addition, it was found that seedling growth measured at 40 months after planting for those growths in pond base was almost 100% greater than those grown on the furrows. Therefore, this finding may be applied for the restoration of abandoned shrimp ponds by growing Nipa palm.

  7. Seasonal evolution of melt ponds on Arctic sea ice

    Science.gov (United States)

    Webster, Melinda A.; Rigor, Ignatius G.; Perovich, Donald K.; Richter-Menge, Jacqueline A.; Polashenski, Christopher M.; Light, Bonnie

    2015-09-01

    The seasonal evolution of melt ponds has been well documented on multiyear and landfast first-year sea ice, but is critically lacking on drifting, first-year sea ice, which is becoming increasingly prevalent in the Arctic. Using 1 m resolution panchromatic satellite imagery paired with airborne and in situ data, we evaluated melt pond evolution for an entire melt season on drifting first-year and multiyear sea ice near the 2011 Applied Physics Laboratory Ice Station (APLIS) site in the Beaufort and Chukchi seas. A new algorithm was developed to classify the imagery into sea ice, thin ice, melt pond, and open water classes on two contrasting ice types: first-year and multiyear sea ice. Surprisingly, melt ponds formed ˜3 weeks earlier on multiyear ice. Both ice types had comparable mean snow depths, but multiyear ice had 0-5 cm deep snow covering ˜37% of its surveyed area, which may have facilitated earlier melt due to its low surface albedo compared to thicker snow. Maximum pond fractions were 53 ± 3% and 38 ± 3% on first-year and multiyear ice, respectively. APLIS pond fractions were compared with those from the Surface Heat Budget of the Arctic Ocean (SHEBA) field campaign. APLIS exhibited earlier melt and double the maximum pond fraction, which was in part due to the greater presence of thin snow and first-year ice at APLIS. These results reveal considerable differences in pond formation between ice types, and underscore the importance of snow depth distributions in the timing and progression of melt pond formation.

  8. Groundwater impact assessment report for the 100-D Ponds

    International Nuclear Information System (INIS)

    The 183-D Water Treatment Facility (WTF) discharges effluent to the 120-0-1 Ponds (100-D Ponds) located north of the 100-D Area perimeter fence. This report satisfies one of the requirements of the Hanford Federal Facility Agreement and Consent Order (Tri-Party Agreement) Milestone M-17-00B as agreed by the US Department of Energy, Washington State Department of Ecology, and the US Environmental Protection Agency. Tri-Party Agreement Milestone M-17-00B includes a requirement to assess impacts to groundwater from disposal of the 183-D WTF effluent to the 100-D Ponds. In addition, the 100-D Ponds are a Resource Conservation and Recovery Act of 1976 treatment, storage, and disposal facility covered by the 100-D Ponds Closure Plan (DOE-RL 1993a). There is evidence of groundwater contamination, primarily nitrate, tritium, and chromium, in the unconfined aquifer beneath the 100-D Area and 100 Areas in general. The contaminant plumes are area wide and are a result of past-practice reactor and disposal operations in the 100-D Area currently being investigated as part of the 100-DR-1 and 100-HR-3 Operable Units (DOE-RL 1992b, 1992a). Based on current effluent conditions, continued operation of the 100-D Ponds will not adversely affect the groundwater quality in the 100-D Area. Monitoring wells near the pond have slightly higher alkaline pH values than wells in the rest of the area. Concentrations of known contaminants in these wells are lower than ambient 100-D Area groundwater conditions and exhibit a localized dilution effect associated with discharges to the pond. Hydraulic impact to the local groundwater system from these discharges is minor. The groundwater monitoring well network for the 100-D Ponds is adequate

  9. Report on the methylmercury situation in Par Pond. Final report

    International Nuclear Information System (INIS)

    Studies are reported on the methylation and accumulation of mercury in fish populations of the pond. Results showed that the majority of the mercury in the fish muscles was in the methyl mercury form. Very low concentrations of mercury were found in the pond sediments. Physiological methylation of the mercury could not be demonstrated by in vivo or in vitro techniques. Organic ligand methylation and reduction of the mercury was shown to be a possible mechanism to account for both the mercury distribution in the pond and the concentrations of methylmercury in the fish. Recommendations are made for remedial treatments to eliminate the mercury problem. (HLW)

  10. Limnological database for Par Pond: 1959 to 1980

    International Nuclear Information System (INIS)

    A limnological database for Par Pond, a cooling reservoir for hot reactor effluent water at the Savannah River Plant, is described. The data are derived from a combination of research and monitoring efforts on Par Pond since 1959. The approximately 24,000-byte database provides water quality, primary productivity, and flow data from a number of different stations, depths, and times during the 22-year history of the Par Pond impoundment. The data have been organized to permit an interpretation of the effects of twenty years of cooling system operations on the structure and function of an aquatic ecosystem

  11. Arctic melt ponds and bifurcations in the climate system

    CERN Document Server

    Sudakov, Ivan; Golden, Kenneth M

    2014-01-01

    Understanding how sea ice melts is critical to climate projections. In the Arctic, melt ponds that develop on the surface of sea ice floes during the late spring and summer largely determine their albedo $-$ a key parameter in climate modeling. Here we explore the possibility of a simple sea ice climate model passing through a bifurcation point $-$ an irreversible critical threshold as the system warms, by incorporating geometric information about melt pond evolution. This study is based on a nonlinear phase transition model for melt ponds, and bifurcation analysis of a simple climate model with ice - albedo feedback as the key mechanism driving the system to a potential bifurcation point.

  12. Greenhouse Gas Exchange in Small Arctic Thaw Ponds

    Science.gov (United States)

    Laurion, I.; Bégin, P. N.; Bouchard, F.; Preskienis, V.

    2014-12-01

    Arctic lakes and ponds can represent up to one quarter of the land surface in permafrost landscapes, particularly in lowland tundra landscapes characterized by ice wedge organic polygons. Thaw ponds can be defined as the aquatic ecosystems associated to thawing of organic soils, either resulting from active layer processes and located above low-center peat polygons (hereafter low-center polygonal or LCP ponds), or resulting from thermokarst slumping above melting ice wedges linked to the accelerated degradation of permafrost (hereafter ice-wedge trough or IWT ponds). These ponds can merge together forming larger water bodies, but with relatively stable shores (hereafter merged polygonal or MPG ponds), and with limnological characteristics similar to LCP ponds. These aquatic systems are very small and shallow, and present a different physical structure than the larger thermokarst lakes, generated after years of development and land subsidence. In a glacier valley on Bylot Island, Nunavut, Canada, thermokarst and kettle lakes together represent 29% of the aquatic area, with a thermal profile resembling those of more standard arctic lakes (mixed epilimnion). The IWT ponds (44% of the area) are stratified for a large fraction of the summer despite their shallowness, while LCP and MPG ponds (27% of the area) show a more homogeneous water column. This will affect gas exchange in these diverse aquatic systems, in addition to their unique microbiota and organic carbon lability that control the production and consumption rates of greenhouse gases. The stratification in IWT ponds generates hypoxic conditions at the bottom, and together with the larger availability of organic carbon, stimulates methanogenesis and limits the mitigating action of methanotrophs. Overall, thaw ponds are largely supersaturated in methane, with IWT ponds dominating the emissions in this landscape (92% of total aquatic emissions estimated for the same valley), and they present large variations in

  13. In-pond raceway systems and catfish disease related cases in west Alabama

    Science.gov (United States)

    Production systems such as in-pond raceway systems (IPRS) and split-pond production systems are providing an alternative to traditional pond culture for raising catfish. Currently, there are over 1,300 water acres of production in Mississippi, Arkansas, and Alabama utilizing split-pond production sy...

  14. Geohydrology and limnology of Walden Pond, Concord, Massachusetts

    Science.gov (United States)

    Colman, John A.; Friesz, Paul J.

    2001-01-01

    The trophic ecology and ground-water contributing area of Walden Pond, in Concord and Lincoln, Mass., were investigated by the U.S. Geological Survey in cooperation with the Massachusetts Department of Environmental Management from April 1997 to July 2000. Bathymetric investigation indicated that Walden Pond (24.88 hectares), a glacial kettle-hole lake with no surface inlet or outlet, has three deep areas. The maximum depth (30.5 meters) essentially was unchanged from measurements made by Henry David Thoreau in 1846. The groundwater contributing area (621,000 square meters) to Walden Pond was determined from water-table contours in areas of stratified glacial deposits and from land-surface contours in areas of bedrock highs. Walden Pond is a flow-through lake: Walden Pond gains water from the aquifer along its eastern perimeter and loses water to the aquifer along its western perimeter. Walden Pond contributing area also includes Goose Pond and its contributing area. A water budget calculated for Walden Pond, expressed as depth of water over the lake surface, indicated that 45 percent of the inflow to the lake was from precipitation (1.215 meters per year) and 55 percent from ground water (1.47 meters per year). The groundwater inflow estimate was based on the average of two different approaches including an isotope mass-balance approach. Evaporation accounted for 26 percent of the outflow from the lake (0.71 meters per year) whereas lake-water seepage to the groundwater system contributed 74 percent of the outflow (1.97 meters per year). The water-residence time of Walden Pond is approximately 5 years. Potential point sources of nutrients to ground water, the Concord municipal landfill and a trailer park, were determined to be outside the Walden Pond groundwater contributing area. A third source, the septic leach field for the Walden Pond State Reservation facilities, was within the groundwater contributing area. Nutrient budgets for the lake indicated that

  15. A Comparison of Methods for Cascade Prediction

    CERN Document Server

    Guo, Ruocheng

    2016-01-01

    Information cascades exist in a wide variety of platforms on Internet. A very important real-world problem is to identify which information cascades can go viral. A system addressing this problem can be used in a variety of applications including public health, marketing and counter-terrorism. As a cascade can be considered as compound of the social network and the time series. However, in related literature where methods for solving the cascade prediction problem were proposed, the experimental settings were often limited to only a single metric for a specific problem formulation. Moreover, little attention was paid to the run time of those methods. In this paper, we first formulate the cascade prediction problem as both classification and regression. Then we compare three categories of cascade prediction methods: centrality based, feature based and point process based. We carry out the comparison through evaluation of the methods by both accuracy metrics and run time. The results show that feature based met...

  16. Cascades on clique-based graphs

    CERN Document Server

    Hackett, Adam

    2013-01-01

    We present an analytical approach to determining the expected cascade size in a broad range of dynamical models on the class of highly-clustered random graphs introduced in [J. P. Gleeson, Phys. Rev. E 80, 036107 (2009)]. A condition for the existence of global cascades is also derived. Applications of this approach include analyses of percolation, and Watts's model. We show how our techniques can be used to study the effects of in-group bias in cascades on social networks.

  17. Lateral Modes in Quantum Cascade Lasers

    Directory of Open Access Journals (Sweden)

    Gregory C. Dente

    2016-03-01

    Full Text Available We will examine the waveguide mode losses in ridge-guided quantum cascade lasers. Our analysis illustrates how the low-loss mode for broad-ridge quantum cascade lasers (QCLs can be a higher-order lateral waveguide mode that maximizes the feedback from the sloped ridge-wall regions. The results are in excellent agreement with the near- and far-field data taken on broad-ridge-guided quantum cascade lasers processed with sloped ridge walls.

  18. Disaster Mythology and Availability Cascades

    Directory of Open Access Journals (Sweden)

    Lisa Grow Sun

    2013-04-01

    Full Text Available Sociological research conducted in the aftermath of natural disasters has uncovered a number of “disaster myths” – widely shared misconceptions about typical post-disaster human behavior. This paper discusses the possibility that perpetuation of disaster mythology reflects an “availability cascade,” defined in prior scholarship as a “self-reinforcing process of collective belief formation by which an expressed perception triggers a chain reaction that gives the perception increasing plausibility through its rising availability in public discourse.” (Kuran and Sunstein 1999. Framing the spread of disaster mythology as an availability cascade suggests that certain tools may be useful in halting the myths’ continued perpetuation. These tools include changing the legal and social incentives of so-called “availability entrepreneurs” – those principally responsible for beginning and perpetuating the cascade, as well as insulating decision-makers from political pressures generated by the availability cascade. This paper evaluates the potential effectiveness of these and other solutions for countering disaster mythology. Las investigaciones sociológicas realizadas tras los desastres naturales han hecho evidentes una serie de “mitos del desastre”, conceptos erróneos ampliamente compartidos sobre el comportamiento humano típico tras un desastre. Este artículo analiza la posibilidad de que la perpetuación de los mitos del desastre refleje una “cascada de disponibilidad”, definida en estudios anteriores como un “proceso de auto-refuerzo de la formación de una creencia colectiva, a través del que una percepción expresada produce una reacción en cadena que hace que la percepción sea cada vez más verosímil, a través de una mayor presencia en el discurso público” (Kuran y Sunstein 1999. Enmarcar la propagación de los mitos del desastre como una cascada de disponibilidad sugiere que ciertas herramientas pueden ser

  19. Spray formation: an inverse cascade

    CERN Document Server

    Ling, Yue; Tryggvason, Gretar; zaleski, Stephane

    2015-01-01

    We present a study of droplet formation in a gas-liquid mixing layer using direct numerical simulation. It is seen that two mechanisms compete to generate the droplets: fingering at the tip of the waves and hole formation in the thin liquid sheet. The three dimensional liquid structures are much shorter than the longitudinal wavelength of the instability at the first instant of their formation. As time evolves, the structures evolves to larger and larger scales, in a way similar to the inverse cascade of length scales in droplet impact and impact crown formation.

  20. Quantum Cascade Laser Frequency Combs

    OpenAIRE

    Faist, Jérôme; Villares, Gustavo; Scalari, Giacomo; Rösch, Markus; Bonzon, Christopher; Hugi, Andreas; Beck, Mattias

    2015-01-01

    It was recently demonstrated that broadband quantum cascade lasers can operate as frequency combs. As such, they operate under direct electrical pumping at both mid-infrared and THz frequencies, making them very attractive for dual-comb spectroscopy. Performance levels are continuously improving, with average powers over 100 mW and frequency coverage of 100 cm$^{-1}$ in the mid-infrared. In the THz range, 10 mW of average power and 600 GHz of frequency coverage are reported. As a result of th...

  1. DFB Quantum Cascade Laser Arrays

    OpenAIRE

    Lee, Benjamin G.; Belkin, Mikhail A.; Pflügl, Christian; Diehl, Laurent; Zhang, Haifei; Audet, Ross M.; MacArthur, Jim B.; Bour, David P.; Corzine, Scott W.; Höfler, Gloria E.; Capasso, Federico

    2009-01-01

    DFB quantum cascade laser (DFB-QCL) arrays operating between 8.7 and 9.4 mum are investigated for their performance characteristics-single-mode selection of the DFB grating, and variability in threshold, slope efficiency, and output power of different lasers in the array. Single-mode selection refers to the ability to choose a desired mode/frequency of laser emission with a DFB grating. We apply a theoretical framework developed for general DFB gratings to analyze DFB-QCL arrays. We calculate...

  2. Availability Cascades & the Sharing Economy

    DEFF Research Database (Denmark)

    Netter, Sarah

    2014-01-01

    In search of a new concept that will provide answers to as to how modern societies should not only make sense but also resolve the social and environmental problems linked with our modes of production and consumption, collaborative consumption and the sharing economy are increasingly attracting...... attention. This conceptual paper attempts to explain the emergent focus on the sharing economy and associated business and consumption models by applying cascade theory. Risks associated with this behavior will be especially examined with regard to the sustainability claim of collaborative consumption. With...

  3. WHISTLER TURBULENCE FORWARD CASCADE VERSUS INVERSE CASCADE: THREE-DIMENSIONAL PARTICLE-IN-CELL SIMULATIONS

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Ouliang [Oracle Corporation, Redwood Shores, CA (United States); Gary, S. Peter [Space Science Institute, Boulder, CO (United States); Wang, Joseph, E-mail: ouliang@usc.edu, E-mail: pgary@lanl.gov, E-mail: josephjw@usc.edu [University of Southern California, Los Angeles, CA (United States)

    2015-02-20

    We present the results of the first fully three-dimensional particle-in-cell simulations of decaying whistler turbulence in a magnetized, homogeneous, collisionless plasma in which both forward cascades to shorter wavelengths, and inverse cascades to longer wavelengths are allowed to proceed. For the electron beta β {sub e} = 0.10 initial value considered here, the early-time rate of inverse cascade is very much smaller than the rate of forward cascade, so that at late times the fluctuation energy in the regime of the inverse cascade is much weaker than that in the forward cascade regime. Similarly, the wavevector anisotropy in the inverse cascade regime is much weaker than that in the forward cascade regime.

  4. A non-conventional isotope separation cascade without any mixing: net cascade

    International Nuclear Information System (INIS)

    A component has different concentrations in the incoming flows at a confluent point in all existing isotope separations cascades for multi-component isotope separation and mixing is inevitable, which results in deterioration of separation performance of the separation cascade. However, realization of no-mixing at a confluent point is impossible with a conventional cascade. A non-conventional isotope separation cascade, net cascade, is found to be able to realize no mixings for all components at confluent points, and its concept is further developed here. No-mixing is fulfilled by requiring symmetrical separation of two specified key components at every stage, and the procedure of realizing no-mixing is presented in detail. Some properties of net cascade are investigated preliminarily, and the results demonstrated the no-mixing property is indeed realized. Net cascade is the only separation cascade that so far possesses the no-mixing property. (authors)

  5. Contingency Analysis of Cascading Line Outage Events

    Energy Technology Data Exchange (ETDEWEB)

    Thomas L Baldwin; Magdy S Tawfik; Miles McQueen

    2011-03-01

    As the US power systems continue to increase in size and complexity, including the growth of smart grids, larger blackouts due to cascading outages become more likely. Grid congestion is often associated with a cascading collapse leading to a major blackout. Such a collapse is characterized by a self-sustaining sequence of line outages followed by a topology breakup of the network. This paper addresses the implementation and testing of a process for N-k contingency analysis and sequential cascading outage simulation in order to identify potential cascading modes. A modeling approach described in this paper offers a unique capability to identify initiating events that may lead to cascading outages. It predicts the development of cascading events by identifying and visualizing potential cascading tiers. The proposed approach was implemented using a 328-bus simplified SERC power system network. The results of the study indicate that initiating events and possible cascading chains may be identified, ranked and visualized. This approach may be used to improve the reliability of a transmission grid and reduce its vulnerability to cascading outages.

  6. Single-Seed Cascades on Clustered Networks

    CERN Document Server

    McSweeney, John K

    2015-01-01

    We consider a dynamic network cascade process developed by Watts applied to a random networks with a specified amount of clustering, belonging to a class of random networks developed by Newman. We adapt existing tree-based methods to formulate an appropriate two-type branching process to describe the spread of a cascade started with a single active node, and obtain a fixed-point equation to implicitly express the extinction probability of such a cascade. In so doing, we also recover a special case of a formula of Hackett et al. giving conditions for certain extinction of the cascade.

  7. Dynamics and structure of energetic displacement cascades

    International Nuclear Information System (INIS)

    This paper summarizes recent progress in the understanding of energetic displacement cascades and the primary state of damage in metals. On the theoretical side, the availability of supercomputers has greatly enhanced our ability to simulate cascades by molecular dynamics. Recent application of this simulation technique to Cu and Ni provides new insight into the dynamics of cascade processes. On the experimental side, new data on ion beam mixing and in situ electron microscopy studies of ion damage at low temperatures reveal the role of the thermodynamic properties of the material on cascade dynamics and structure. 38 refs., 9 figs

  8. Island ponds mitigation monitoring and reporting : Year 4 – 2009

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The Santa Clara Valley Water District and the U.S. Fish and Wildlife Service Don Edwards National Wildlife Refuge implemented the Island Ponds Restoration Project...

  9. Island ponds mitigation monitoring and reporting : Year 3 – 2008

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This report presents Year 3 2008 monitoring results for Island Ponds Restoration Project on Don Edwards San Francisco Bay NWR. The Santa Clara Valley Water District...

  10. Bacterial flora of pond reared Penaeus indicus (Milne Edwards)

    Digital Repository Service at National Institute of Oceanography (India)

    Singh, I.S.B.; Lakshmanaperumalsamy, P.; Chandramohan, D.

    group, Vibrio and Pseudomonas as the major genera, much different from that of pond sediment from where the animals collected detritus, indicating the animals' selective feeding behaviour. Intestine of prawns was found to be a congenial environment...

  11. Modeling the summertime evolution of sea-ice melt ponds

    DEFF Research Database (Denmark)

    Lüthje, Mikael; Feltham, D.L.; Taylor, P.D.; Worster, M.G.

    2006-01-01

    We present a mathematical model describing the summer melting of sea ice. We simulate the evolution of melt ponds and determine area coverage and total surface ablation. The model predictions are tested for sensitivity to the melt rate of unponded ice, enhanced melt rate beneath the melt ponds......, vertical seepage, and horizontal permeability. The model is initialized with surface topographies derived from laser altimetry corresponding to first-year sea ice and multiyear sea ice. We predict that there are large differences in the depth of melt ponds and the area of coverage between the two types of...... ice. We also find that the vertical seepage rate and the melt rate of unponded ice are important in determining the total surface ablation and area covered by melt ponds....

  12. Environmental Assessment : Two Ponds Wetland Preserve, Arvada, Colorado

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Environmental Assessment for the acquisition of approximately 80 acres known as Two Ponds Wetland Preserve. The Fish and Wildlife Service has responded to selected...

  13. South Bay Salt Ponds Restoration Project : Final Data Acquisition Plan

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This document provides the Data Acquisition Plan for the South Bay Salt Pond Restoration Project. The purpose of the Data Acquisition Plan is to guide the...

  14. Western Pond Turtle Observations - Region 1 [ds313

    Data.gov (United States)

    California Department of Resources — This dataset was developed in an effort to compile Western Pond Turtle (Clemmys marmorata) observations in CDFG Region 1. Steve Burton (CDFG Staff Environmental...

  15. The Trail Inventory of Kealia Pond NWR [Cycle 2

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The purpose of this report is to create a baseline inventory of all nonmotorized trails on Kealia Pond National Wildlife Refuge. Trails in this inventory are...

  16. Kealia Pond National Wildlife Refuge: Comprehensive Conservation Plan

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This Comprehensive Conservation Plan (CCP) was written to guide management on Kealia Pond Wildlife Refuge for the next 15 years. This plan outlines the Refuge...

  17. Water quality assessment of razorback sucker grow-out ponds

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Water quality parameters had never been assessed in these grow-out ponds. Historically growth, condition, and survival of razorback suckers have been variable...

  18. EXPERIMENTAL INVESTIGATION OF SOLAR POND PERFORMANCE IN KARABUK ENVIRONMENT

    Directory of Open Access Journals (Sweden)

    Mehmet ÖZKAYMAK

    2004-01-01

    Full Text Available The solar energy, one of the alternative energy sources, can be economically and cheaply and efficiently collected with solar ponds. In this study, varying concentrations of sodium carbonate dilution in the solar pond in terms of heat storage performance has been examined. Experiment apparatus has been located Zonguldak Karaelmas University Karabük Technical Education Faculty. Five experiments with different density levels have been done and the changes in the temperature and density have been presented graphically within the solar pond. The experiments show that the temperature difference between the bottom and top level of solar pond is max. 21 °C and the highest temperature in lower convective zone (LCZ has been measured as 49 °C.

  19. Trustom Pond National Wildlife Refuge: Comprehensive Conservation Plan

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This Comprehensive Conservation Plan (CCP) was written to guide management on Trustom Pond NWR for the next 15 years. This plan outlines the Refuge vision and...

  20. Bank layout of spray nozzles in a spray pond

    International Nuclear Information System (INIS)

    The efficiency of the spray pond performance is dependent on the type of spray nozzles. The investigations conducted at the B.E.Vedeneev VNIIG indicated that tangential spray nozzles hold much promise as they are reliable in operation and do not require careful centering during assembly. This is confirmed by special studies which showed that the cooling capacity of the sprayer plume does not change if the nozzle deflects by up to 30 degree from the vertical, whereas it decreases by less than 10% if the nozzle is inclined at an angle of 45 degree. Taking the aforesaid into consideration, a spray pond with a bank layout of spray nozzles has been constructed at the Takhiatashskaya thermal power plant. The construction of the spray pond was carried out in a non-constricted channel without shutting down the operating power plant. On-site studies of the first stage of the spray pond proved its reliability and maneuverability at the startup

  1. Pond Creek National Wildlife Refuge: Comprehensive Conservation Plan

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This Comprehensive Conservation Plan (CCP) was written to guide management on Pond Creek NWR for the next 15 years. This plan outlines the Refuge vision and purpose...

  2. Investigation of the environmental impacts of sedimentation in Anzali Pond

    Science.gov (United States)

    Barmal, Milad; Neshaei, Seyed Ahmad; Farzan, Niloofar

    2016-04-01

    Anzali harbor is the most essential transportation pole between Iran and other countries of the Caspian Sea basin. Anzali pond is an important ecosystem in the region due to its unique plant and animal species. In order to determine the effects of interaction between pond and sea, a series of in-depth studies and analysis on the pattern of sedimentation in Anzali harbor and pond were performed. The study area is Anzali harbor and pond which is located in southwest of the Caspian Sea in Iran. In recent years the economical importance and improvement program of this region has devoted many scientists and authorities attention to itself. In this paper, researches on environmental impact by sediment and pollution in this zone are performed. Analysis indicates that by disposal of sediment and pollution in this area, the physical and chemical quality of water has declined. Some practical suggestions are made to improve the quality of the studied region in terms of environmental aspects.

  3. Solar-induced thermal activity and stratification in pond water

    CERN Document Server

    Brownridge, James D

    2015-01-01

    Ponds are universally used to store water for a large number of uses. With the increasing demand for more fresh water, ponds, lakes and reservoirs are likely to be constructed on a larger scale. We must understand the effects of environmental changes on fresh water if we are to most efficiently utilize this resource. This study undertakes to increase our understanding of the rate of thermal response of ponds and other bodies of water to every-day environmental changes. The central research agenda is to investigate how the temperature of pond water from top to bottom responds to the day/night cycle, changes in air temperature just above the surface, cloud conditions, and other sudden environmental changes. Data collection for this study spanned October 2007 to June 2011 and had a continuous time resolution of 50 seconds.

  4. West Knox Pond water budget and water quality

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The purpose of this report is to analyze the water budget and water quality for West Knox Pond for the May through September period of 2002 and 2003. The...

  5. Habitat Management Plan for Pond Creek National Wildlife Refuge

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The Pond Creek National Wildlife Refuge Habitat Management Plan provides a longterm vision and specific guidance on managing habitats for the resources of concern...

  6. REMOVAL OF HELMINTH PARASITIC EGGS FROM WASTE STABILIZATION PONDS AT SHIMOGA

    OpenAIRE

    M. SHANTHALA; Hosetti, B. B.; REBECCA STOTT

    2007-01-01

    Helminth ova removal rates from waste stabilization pond effluents under tropical conditions ofShimoga using both laboratory and field modal ponds was undertaken. The helminthes were removedto the tune of 100% from laboratory model batch system ponds within 15 days of detention timeand it was only 65% in case of laboratory model continuos flow system ponds. The observation infield model ponds revealed an average 90% removal with 10 days retention time. A 100% removalcan not be expected both i...

  7. Terrestrial habitat use by western pond turtles (Actinemys marmorata) in the sierra foothills

    OpenAIRE

    Zaragoza, G; Rose, JP; Purcell, K; Todd, BD

    2015-01-01

    © 2015 Society for the Study of Amphibians and Reptiles. Western Pond Turtles (Actinemys marmorata) are endemic to western North America and are found in a diversity of aquatic habitats. To date, few studies have examined the ecology of populations in ephemeral or intermittent ponds. Here, we studied the terrestrial habitat requirements of Western Pond Turtles in an intermittent pond that dries in years with below-average rainfall. We tracked terrestrial movements of Western Pond Turtles in a...

  8. A Mathematical Model for the Removal of Organic Mater in Stabilization Ponds

    OpenAIRE

    Medri Waldir; Medri Vandir

    2002-01-01

    This work presents an application to systemize the construction of ponds systems for treatment of domestic sewage. It consisted of two anaerobic ponds operated in parallel during May/97 to April/99. These were connected in series with a chicaned facultative pond. The treatment system was controlled with samples collected from the crude sewage (compound sample), in the affluents and effluents of the ponds and along the flux of the anaerobic and facultative ponds. The following parameters were ...

  9. Dissolved organic matter photolysis in Canadian arctic thaw ponds

    International Nuclear Information System (INIS)

    The abundant thaw lakes and ponds in the circumarctic receive a new pool of organic carbon as permafrost peat soils degrade, which can be exposed to significant irradiance that potentially increases as climate warms and ice cover shortens. Exposure to sunlight is known to accelerate the transformation of dissolved organic matter (DOM) into molecules that can be more readily used by microbes. We sampled the water from two common classes of ponds found in the ice-wedge system of continuous permafrost regions of Canada, polygonal and runnel ponds, and followed the transformation of DOM over 12 days by looking at dissolved organic carbon (DOC) concentration and DOM absorption and fluorescence properties. The results indicate a relatively fast decay of color (3.4 and 1.6% loss d−1 of absorption at 320 nm for the polygonal and runnel pond, respectively) and fluorescence (6.1 and 8.3% loss d−1 of total fluorescent components, respectively) at the pond surface, faster in the case of humic-like components, but insignificant losses of DOC over the observed period. This result indicates that direct DOM mineralization (photochemical production of CO2) is apparently minor in thaw ponds compared to the photochemical transformation of DOM into less chromophoric and likely more labile molecules with a greater potential for microbial mineralization. Therefore, DOM photolysis in arctic thaw ponds can be considered as a catalytic mechanism, accelerating the microbial turnover of mobilized organic matter from thawing permafrost and the production of greenhouse gases, especially in the most shallow ponds. Under a warming climate, this mechanism will intensify as summers lengthen. (letter)

  10. Seasonal dynamics of fish assemblage in a pond canal

    Czech Academy of Sciences Publication Activity Database

    Musil, J.; Adámek, Zdeněk; Baranyi, Ch.

    2007-01-01

    Roč. 15, č. 3-4 (2007), s. 217-226. ISSN 0967-6120. [New Challenges in Pond Aquaculture . České Budějovice, 26.04.2005-28.04.2005] Institutional research plan: CEZ:AV0Z60930519 Keywords : fish assemblage * pond canal * species richness * seasonal dynamics * alien species Subject RIV: GL - Fishing Impact factor: 0.828, year: 2007

  11. Formation of the "ponds" on asteroid (433) Eros by fluidization

    Science.gov (United States)

    Sears, D. W. G.; Tornabene, L. L.; Osinski, G. R.; Hughes, S. S.; Heldmann, J. L.

    2015-11-01

    The "ponds" on asteroid (433) Eros are fine-grained deposits approximating flat (quasi-equipotential) surfaces with respect to local topographic depressions (e.g., craters) in spacecraft images. These ponds are discussed in the context of laboratory simulation experiments, crater-related ponded and pitted deposits observed on Mars and Vesta, terrestrial phreatic craters, and degassing features associated with eroded impact craters on Earth. While the details of formation of these features on Mars, Vesta and the Earth are thought to be different, they all include mechanisms that require the interactions between surface materials and volatiles (e.g., water vapor). Indeed, analogous features similar to the Eros ponds can be reproduced in the laboratory by the release of vapor (ice sublimation, water evaporation, or N2) through an unconsolidated regolith (independent of regolith composition). Eros is widely thought to be dry, but the discovery of exogenic water on Vesta, and recent arguments that subsurface water might be present in the inner asteroid belt suggest that endogenic water might also be present and serve as a source of the gases produced in the ponds. The amount of water required is comparable to the amount of water observed in little-metamorphosed ordinary chondrites (a few wt%). The primary morphologic characteristics of the Eros ponds can be explained in this model. The heat source for degassing could have been solar heating following transfer from a main belt orbit to a near Earth orbit. Although other hypotheses (e.g., electrostatic levitation, seismic shaking, and comminution of boulders) can account for most of the features of the ponds, recent observations regarding the role of volatiles on planetary surfaces, our laboratory experiments, and fluidization deposits on active comets suggests that degassing is a reasonable hypothesis to be considered and further tested for explaining the Eros ponds, and similar features on other bodies.

  12. Modeling the summertime evolution of sea-ice melt ponds

    OpenAIRE

    Lüthje, M.; D. L. Feltham; Taylor, P D; Worster, M. G.

    2006-01-01

    1] We present a mathematical model describing the summer melting of sea ice. We simulate the evolution of melt ponds and determine area coverage and total surface ablation. The model predictions are tested for sensitivity to the melt rate of unponded ice, enhanced melt rate beneath the melt ponds, vertical seepage, and horizontal permeability. The model is initialized with surface topographies derived from laser altimetry corresponding to first-year sea ice and multiyear sea ice. We predict t...

  13. Homestead fish pond and the environment in Nigeria

    OpenAIRE

    Okaeme, A.N.

    1999-01-01

    Homestead fish culture is a recent innovation for mass production of fish at backyard in Nigeria. The processes of pond construction often have resulted in soil disturbances, vegetation losses, and creation of new aquatic environment. The paper discusses homestead ponds in Nigeria, their potential impact on the environment which includes erosion, over flooding, pest and disease, accident risk, undesired fossil fuel production, vegetation destruction and fish genetic conservation, strategies f...

  14. Garden ponds as potential introduction pathway of ornamental crayfish

    OpenAIRE

    Patoka J.; Petrtýl M.; Kalous L.

    2014-01-01

    The private stocking of ornamental crayfish in garden ponds was discussed in previous studies, but there is a lack of detailed analysis for better understanding of this introduction pathway. The Czech Republic is one of leading EU countries in trade with ornamental crayfish and private garden ponds are popular among people. The crayfish keepers in the country were interviewed by self-administered questionnaire to gather data about principal characteristics of the keepers and detailed informat...

  15. Pond culture of mud crab (Scylla serrata): an economic analysis

    OpenAIRE

    Samonte, G. P.B.; Agbayani, R.F.

    1992-01-01

    The findings are presented of a study conducted to determine the economic feasibility of the pond culture of mud crab (Scylla serrata) at various stocking densities. Investments, costs, and returns are given for a 1 ha crab monoculture at 4 stocking densities - 5000, 10,000, 15,000 and 20,000. Results show that mud crab monoculture in brackishwater ponds is economically feasible at stocking densities of 5000/ha and 10,000/ha.

  16. Nature of Flow and Gas Dynamics Below Spreading Ponds

    OpenAIRE

    Jordan F Clark; Avisar, Dror; Hudson, G. Bryant

    2005-01-01

    The El Rio Spreading Grounds, an area of artificial recharge, lies within a regional groundwater depression. It consists of ten small ponds surrounded by eight production wells. A deliberate tracer experiment using sulfur hexafluoride (SF6) and an isotope of helium (3He) was conducted to determine groundwater flow. The tracer was continuously injected into one pond for one week prior to a ~50 day period of no recharge. At the time of the experiment, the artificial recharge rate through the hi...

  17. Tube Discovered During Decommissioning of Pond, Dounreay, United Kingdom

    International Nuclear Information System (INIS)

    An underwater survey was conducted as part of preparations to decommission the pond adjacent to the Dounreay Materials Test Reactor (MTR). Investigation of a higher than expected radiation reading identified a hollow metal tube on the floor of the pond. The tube measured approximately 45 cm in length and 4.5 cm in diameter. It posed no risk to the workers in its position because it was beneath 4 m of water

  18. Efficiency of aquatic macrophytes to treat Nile tilapia pond effluents

    OpenAIRE

    Henry-Silva Gustavo Gonzaga; Camargo Antonio Fernando Monteiro

    2006-01-01

    The effluents from fish farming can increase the quantity of suspended solids and promote the enrichment of nitrogen and phosphorus in aquatic ecosystems. In this context, the aim of this work was to evaluate the efficiency of three species of floating aquatic macrophytes (Eichhornia crassipes, Pistia stratiotes and Salvinia molesta) to treat effluents from Nile tilapia culture ponds. The effluent originated from a 1,000-m² pond stocked with 2,000 male Nile tilapia Oreochromis niloticus. The ...

  19. Cascade decays of hollow ions

    International Nuclear Information System (INIS)

    A multiple-electron-emission process for atoms with one or more inner-shell vacancies is treated using the radiative- and Auger-electron-emission cascade model, in which inner-shell holes are assumed to decay by sequentially emitting radiations and/or Auger electrons. Such hollow ions are produced by synchrotron irradiation of atomic targets and in ion-surface interactions with multiple-electron transfers. The final charge-state distribution is determined by the Auger and radiative branching ratios at each stage of the decay sequence. At intermediate stages of cascade, hollow ions with more than one hole in different ionization stages are created. The Ne, Mg, and Fe14+ ions with the initial 1s, 2s, and 2p vacancies are considered in detail, and the core charge dependence of the maximum charge state is studied. The hollow Mg ion with double initial 1s holes is analyzed, and the result compared with that for the case of one 1s hole. The peak is shifted more than two units to a higher degree of ionization. The correlated shake-off and shake-up multiple-electron processes are not considered, but they are expected to cause further shifts

  20. Time evolution of cascade decay

    CERN Document Server

    Boyanovsky, Daniel

    2014-01-01

    We study non-perturbatively the time evolution of cascade decay for generic fields $\\pi \\rightarrow \\phi_1\\phi_2\\rightarrow \\phi_2\\chi_1\\chi_2$ and obtain the time dependence of amplitudes and populations for the resonant and final states. We analyze in detail the different time scales and the manifestation of unitary time evolution in the dynamics of production and decay of resonant intermediate and final states. The probability of occupation (population) ``flows'' as a function of time from the initial to the final states. When the decay width of the parent particle $\\Gamma_\\pi$ is much larger than that of the intermediate resonant state $\\Gamma_{\\phi_1}$ there is a ``bottleneck'' in the flow, the population of resonant states builds up to a maximum at $t^* = \\ln[\\Gamma_\\pi/\\Gamma_{\\phi_1}]/(\\Gamma_\\pi-\\Gamma_{\\phi_1})$ nearly saturating unitarity and decays to the final state on the longer time scale $1/\\Gamma_{\\phi_1}$. As a consequence of the wide separation of time scales in this case the cascade decay ...

  1. Physics of interband cascade lasers

    Science.gov (United States)

    Vurgaftman, I.; Bewley, W. W.; Merritt, C. D.; Canedy, C. L.; Kim, C. S.; Abell, J.; Meyer, J. R.; Kim, M.

    2012-01-01

    The interband cascade laser (ICL) is a unique device concept that combines the effective parallel connection of its multiple-quantum-well active regions, interband active transitions, and internal generation of electrons and holes at a semimetallic interface within each stage of the device. The internal generation of carriers becomes effective under bias, and the role of electrical injection is to replenish the carriers consumed by recombination processes. Major strides have been made toward fundamentally understanding the rich and intricate ICL physics, which has in turn led to dramatic improvements in the device performance. In this article, we review the physical principles of the ICL operation and designs of the active region, electron and hole injectors, and optical waveguide. The results for state-of- the-art ICLs spanning the 3-6 μm wavelength range are also briefly reviewed. The cw threshold input powers at room temperature are more than an order of magnitude lower than those for quantum cascade lasers throughout the mid-IR spectral range. This will lengthen battery lifetimes and greatly relax packaging and size/weight requirements for fielded sensing systems.

  2. Compatibility determination : Waterfowl hunting on 5,500 acres of former commercial salt ponds : Don Edwards San Francisco Bay National Wildlife Refuge : Alviso and Ravenswood Salt Ponds

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This Compatibility Determination concerns the proposed waterfowl (duck, goose, and coot) hunting program for the Alviso and Ravenswood Salt Ponds. Ponds AB1, A2E,...

  3. Water requirement model for salt gradient solar ponds

    Energy Technology Data Exchange (ETDEWEB)

    Batty, J.C.; Riley, J.P.; Panahi, Z.

    1987-01-01

    A model for predicting the salt gradient solar pond (SGSP) area that could be maintained with a given water supply is presented together with several specific applications. For example, based on 30-year average water flows, the model predicts that 1.93 x 10/sup 9/ m/sup 2/ (477,000 acres) of solar ponds, 1.02 x 10/sup 9/ m/sup 2/ (253,000 acres) of evaporation ponds to recycle salt, and 0.51 x 10/sup 9/ m/sup 2/ (125,000 acres) of freshwater storage reservoirs could be maintained at the Great Salt Lake of Utah. Water use requirements per unit of electrical energy from solar ponds are calculated as 600,000 m/sup 3//MW x yr. This is roughly 30 times the water evaporated per unit of electrical energy from coal-fired generating plants using wet cooling towers, but substantially less than water evaporation losses per unit of electrical energy produced from typical hydropower dams and reservoirs. It is concluded that water use requirements for solar ponds, although not necessarily prohibitive, are substantial; and in many locations may be the physical factor that limits solar pond development. 9 references, 4 figures, 5 tables.

  4. 2101-M pond closure plan. Volume 1, Revision 2

    Energy Technology Data Exchange (ETDEWEB)

    Izatt, R. D.; Lerch, R. E.

    1993-06-01

    This document describes activities for the closure of a surface impoundment (2101-M Pond) at the Hanford Site. The 2101-H Pond was initially constructed in 1953 to serve as a drainage collection area for the 2101-H Building. (Until the Basalt Waste Isolation Project (BWIP) Laboratory was constructed in the 2101-M Building in 1979--1981, the only source contributing discharge to the pond was condensate water from the 2101-H Building heating, ventilation, and air conditioning (HVAC) system. The drains for the BWIP Laboratory rooms were plumbed into a 4-in., cast-iron, low-pressure drain pipe that carries waste water from the HVAC system to the pond. During the active life of the BWIP Laboratory, solutions of dissolved barium in groundwater samples were discharged to the 2101-M Pond via the laboratory drains. As a result of the discharges, a Part A permit application was initially submitted to the Washington State Department of Ecology (Ecology) in August 1986 which designates the 2101-M Pond as a surface impoundment.

  5. Geomembrane selection criteria for uranium tailings ponds

    International Nuclear Information System (INIS)

    The selection criteria, particularly those involving chemical compatibility, of geomembranes to be used in ponds at uranium mill operations are discussed. The principal functional criteria which a geomembrane must meet for this application are: (1) a specified service life and (2) low permeability. Chemical compatibility with the waste is essential in meeting these functional criteria. In two different types of aging tests using simulated acidic uranium mill waste, degradation of chemical and physical properties were examined in geomembranes of high-density polyethylene, polyvinyl chloride, and chlorosulfonated polyethylene. Compatibility tests according to the National Sanitation Foundation procedures are recommended to ascertain the stability of certain physical properties of the proposed geomembrane. Actual experience with a specific geomembrane in an identical application is probably the best method to assure compatibility; however, this experience is frequently not available. Experience with a geomembrane in similar applications is valuable in the selection process, however, small differences in either the geomembrane formulation or the waste composition may result in large differences in performance of the geomembrane. It is likely that many geomembranes have acceptable chemical stability for typical uranium mill applications, therefore, additional factors in the selection processes will include seaming characteristics, mechanical properties, site characteristics, and costs

  6. Actinide behavior in a freshwater pond

    International Nuclear Information System (INIS)

    Long-term investigations of solution chemistry in an alkaline freshwater pond have revealed that actinide oxidation state behavior, particularly that of plutonium, is complex. The Pu(V,VI) fraction was predominant in solution, but it varied over the entire range reported from other natural aquatic environments, in this case, as a result of intrinsic biological and chemical cycles (redox and pH-dependent phenomena). A strong positive correlation between plutonium (Pu), but not uranium (U), and hydroxyl ion over the observation period, especially when both were known to be in higher oxidation states, was particularly notable. Coupled with other examples of divergent U and Pu behavior, this result suggests that Pu(V), or perhaps a mixture of Pu(V,VI), was the prevalent oxidation state in solution. Observations of trivalent actinide sorption behavior during an algal bloom, coupled with the association with a high-molecular weight (nominally 6000 to 10,000 mol wt) organic fraction in solution, indicate that solution-detritus cycling of organic carbon, in turn, may be the primary mechanism in amercium-curium (Am-Cm) cycling. Sorption by sedimentary materials appears to predominate over other factors controlling effective actinide solubility and may explain, at least partially, the absence of an expected strong positive correlation between carbonate and dissolved U. 49 references, 6 figures, 12 tables

  7. Ecological aspects of pond fish culture intensification. 2. The effect of atmospheric conditions on the physical parameters of pond environment

    International Nuclear Information System (INIS)

    The intensification of common carp pond rearing through the introduction of large amounts of organic and mineral matter and an increase in stocking density resulted in a reduction of sunlight penetration into the water. Abundant suspended matter absorbed most of the solar radiation in the surface water layer resulting in thermal stratification and a reduction of the average temperature in ponds of intensive fish culture

  8. Nonlinearly Driven Second Harmonics of Alfven Cascades

    International Nuclear Information System (INIS)

    In recent experiments on Alcator C-Mod, measurements of density fluctuations with Phase Contrast Imaging through the plasma core show a second harmonic of the basic Alfven Cascade (AC) signal. The present work describes the perturbation at the second harmonic as a nonlinear sideband produced by the Alfven Cascade eigenmode via quadratic terms in the MHD equations. (author)

  9. A NOTE ON VECTOR CASCADE ALGORITHM

    Institute of Scientific and Technical Information of China (English)

    Qiu-hui Chen; Jin-zhao Liu; Wen-sheng Zhang

    2002-01-01

    The focus of this paper is on the relationship between accuracy of multivariate refinable vector and vector cascade algorithm. We show that, if the vector cascade algorithm (1.5) with isotropic dilation converges to a vector-valued function with regularity, then the initial function must satisfy the Strang-Fix conditions.

  10. Fractal dimensionality of cascades of atomic displacements

    International Nuclear Information System (INIS)

    The cascades of opening displacements, formed during irradiation of solids are the most typical process of dissipation of the energy of incident particles and the generation of radiation defects. The aim of the present work is the examination of the energy dependence of the fractal dimensionality of the cascades of atomic displacements in the solid

  11. Cascading costs: An economic nitrogen cycle

    Institute of Scientific and Technical Information of China (English)

    William R. Moomaw; Melissa B. L. Birch

    2005-01-01

    The chemical nitrogen cycle is becoming better characterized in terms of fluxes and reservoirs on a variety of scales. Galloway has demonstrated that reactive nitrogen can cascade through multiple ecosystems causing environmental damage at each stage before being denitrifled to N2. We propose to construct a parallel economic nitrogen cascade (ENC) in which economic impacts of nitrogen fluxes can be estimated by the costs associated with each stage of the chemical cascade. Using economic data for the benefits of damage avoided and costs of mitigation in the Chesapeake Bay basin, we have constructed an economic nitrogen cascade for the region. Since a single tonne of nitrogen can cascade through the system, the costs also cascade.Therefore evaluating the benefits of mitigating a tonne of reactive nitrogen released needs to consider the damage avoided in all of the ecosystems through which that tonne would cascade.The analysis reveals that it is most cost effective to remove a tonne of nitrogen coming from combustion since it has the greatest impact on human health and creates cascading damage through the atmospheric, terrestrial, aquatic and coastal ecosystems. We will discuss the implications of this analysis for determining the most cost effective policy option for achieving environmental quality goals.

  12. Direct Experimental Assessment of Microbial Activity in North Pond Sediments

    Science.gov (United States)

    Ferdelman, T. G.; Picard, A.; Morando, M.; Ziebis, W.

    2009-12-01

    North Pond, an isolated sediment pond located at 22°45’N on the western flank of the Mid-Atlantic Ridge, offered the opportunity to study microbial activities in deeply-buried low-activity sediments. About 8 x 15 km in size with sediment maximum thickness of about 300 m, North Pond is completely surrounded by exposed 7 Ma old basement. North Pond lies above the carbonate compensation depth at a water depth about 4500 m; hydrostatic pressure at the seafloor is about 45 MPa and the temperature is near 2°C. During the a R/V MS Merian cruise (MSM-11/1) in February -March 2009, 14 gravity cores of up to 9 m length were successfully obtained, from which samples were taken with 1-m resolution for experimental activity measurements. The goal of the experimental work was 1) to examine potential metabolic pathways in North Pond sediments and carbon assimilation pathways in this low-energy environment, and 2) explore the effects of pressure on microbial metabolic activities. As dissolved oxygen penetrated through all depths, sediments were aerobically sampled, processed and incubated at 4°C. Selected samples were immediately stored at in situ pressure until further use. The microbial uptake of both organic and inorganic carbon in selected North Pond sediment samples was investigated by following the fate of 14C in radio-labeled organic and organic compounds in North Pond sediment slurry incubations. Shipboard and on-shore experiments using 14C-leucine, 14C-glucose and 14C-bicarbonate were performed on selected cores. Day- to month- incubations were performed at 4°C. Parallel incubations were conducted at atmospheric pressure (0.1 MPa) and in situ pressure (~45 MPa). Either whole cell extraction (Kallmeyer et al., Limnol. Oceanogr.: Methods 6, 2008, 238-245) or protein-DNA extraction was carried on after various incubations to determine the fraction of 14C incorporated into cellular components. Formation of 14C-labeled CO2 was determined on samples incubated with 14C

  13. High rates of methane emissions from south taiga wetland ponds.

    Science.gov (United States)

    Glagolev, M.; Kleptsova, I.; Maksyutov, S.

    2012-04-01

    Since wetland ponds are often assumed to be insignificant sources of methane, there is a limited data about its fluxes. In this study, we found surprisingly high rates of methane emission at several shallow ponds in the south taiga zone of West Siberia. Wetland ponds within the Great Vasyugan Mire ridge-hollow-pool patterned bog system were investigated. 22 and 24 flux measurements from ponds and surrounded mires, respectively, were simultaneously made by a static chamber method in July, 2011. In contrast to previous measurements, fluxes were measured using the small boat with floated chamber to avoid disturbance to the water volume. Since the ebullition is most important emission pathway, minimization of physical disturbance provoking gas bubbling significantly increases the data accuracy. Air temperature varied from 15 to 22° C during the measurements, and pH at different pond depths - from 4.4 to 5. As it was found, background emission from surrounding ridges and hollows was 1.7/2.6/3.3 mgC·m-2·h1 (1st/2nd/3rd quartiles). These rates are in a perfect correspondence with the typical methane emission fluxes from other south taiga bogs. Methane emission from wetland ponds turned out to be by order of magnitude higher (9.3/11.3/15.6 mgC·m-2·h1). Comparing to other measurements in West Siberia, many times higher emissions (70.9/111.6/152.3 mgC·m-2·h1) were found in forest-steppe and subtaiga fen ponds. On the contrary, West Siberian tundra lakes emit methane insignificantly, with the flux rate close to surrounding wetlands (about 0.2-0.3 mgC·m-2·h1). Apparently, there is a naturally determined distribution of ponds with different flux rates over different West Siberia climate-vegetation zones. Further investigations aiming at revelation of the zones with different fluxes would be helpful for total flux revision purposes. With respect to other studies, high emission rates were already detected, for instance, in Baltic ponds (Dzyuban, 2002) and U.K. lakes

  14. Cascade Error Projection: An Efficient Hardware Learning Algorithm

    Science.gov (United States)

    Duong, T. A.

    1995-01-01

    A new learning algorithm termed cascade error projection (CEP) is presented. CEP is an adaption of a constructive architecture from cascade correlation and the dynamical stepsize of A/D conversion from the cascade back propagation algorithm.

  15. Multiscales and cascade in isotropic turbulence

    CERN Document Server

    Ran, Zheng

    2010-01-01

    The central problem of fully developed turbulence is the energy cascading process. It has revisited all attempts at a full physical understanding or mathematical formulation. The main reason for this failure are related to the large hierarchy of scales involved, the highly nonlinear character inherent in the Navier-Stokes equations, and the spatial intermittency of the dynamically active regions. Richardson has described the interplay between large and small scales and the phenomena so described are known as the Richardson cascade. This local interplay also forms the basis of a theory by Kolmogorov. In this letter, we use the explicit map method to analyze the nonlinear dynamical behavior for cascade in isotropic turbulence. This deductive scale analysis is shown to provide the first visual evidence of the celebrated Richardson cascade, and reveals in particular its multiscale character. The results also indicate that the energy cascading process has remarkable similarities with the deterministic construction...

  16. Stochastic annealing simulation of cascades in metals

    Energy Technology Data Exchange (ETDEWEB)

    Heinisch, H.L.

    1996-04-01

    The stochastic annealing simulation code ALSOME is used to investigate quantitatively the differential production of mobile vacancy and SIA defects as a function of temperature for isolated 25 KeV cascades in copper generated by MD simulations. The ALSOME code and cascade annealing simulations are described. The annealing simulations indicate that the above Stage V, where the cascade vacancy clusters are unstable,m nearly 80% of the post-quench vacancies escape the cascade volume, while about half of the post-quench SIAs remain in clusters. The results are sensitive to the relative fractions of SIAs that occur in small, highly mobile clusters and large stable clusters, respectively, which may be dependent on the cascade energy.

  17. MAPK Cascades in Guard Cell Signal Transduction.

    Science.gov (United States)

    Lee, Yuree; Kim, Yun Ju; Kim, Myung-Hee; Kwak, June M

    2016-01-01

    Guard cells form stomata on the epidermis and continuously respond to endogenous and environmental stimuli to fine-tune the gas exchange and transpirational water loss, processes which involve mitogen-activated protein kinase (MAPK) cascades. MAPKs form three-tiered kinase cascades with MAPK kinases and MAPK kinase kinases, by which signals are transduced to the target proteins. MAPK cascade genes are highly conserved in all eukaryotes, and they play crucial roles in myriad developmental and physiological processes. MAPK cascades function during biotic and abiotic stress responses by linking extracellular signals received by receptors to cytosolic events and gene expression. In this review, we highlight recent findings and insights into MAPK-mediated guard cell signaling, including the specificity of MAPK cascades and the remaining questions. PMID:26904052

  18. Network reconstruction from infection cascades

    CERN Document Server

    Braunstein, Alfredo

    2016-01-01

    Reconstructing propagation networks from observations is a fundamental inverse problem, and it's crucial to understand and control dynamics in complex systems. Here we show that it is possible to reconstruct the whole structure of an interaction network and to simultaneously infer the complete time course of activation spreading, relying just on single snapshots of a small number of activity cascades. The method, that we called Inverse Dynamics Network Reconstruction (IDNR), is shown to work successfully on several synthetic and real networks, inferring the networks and the sources of infection based on sparse observations, including single snapshots. IDNR is built on a Belief Propagation approximation, that has an impressive performance in a wide variety of topological structures. The method can be applied in absence of complete time-series data by providing a detailed modeling of the posterior distribution of trajectories conditioned to the observations. Furthermore, we show by experiments that the informat...

  19. Multifunctional Cascaded Metamaterials: Integrated Transmitarrays

    CERN Document Server

    Elsakka, Amr A; Faniayeu, Ihar A; Tcvetkova, Svetlana N; Tretyakov, Sergei A

    2016-01-01

    Control of electromagnetic waves using engineered materials is very important in a wide range of applications, therefore there is always a continuous need for new and more efficient solutions. Known natural and artificial materials and surfaces provide a particular functionality in the frequency range they operate but cast a "shadow" and produce reflections at other frequencies. Here, we introduce a concept of multifunctional engineered materials that possess different predetermined functionalities at different frequencies. Such response can be accomplished by cascading metasurfaces (thin composite layers) that are designed to perform a single operation at the desired frequency and are transparent elsewhere. Previously, out-of-band transparent metasurfaces for control over reflection and absorption were proposed. In this paper, to complete the full set of functionalities for wave control, we synthesize transmitarrays that tailor transmission in a desired way, being "invisible" beyond the operational band. The...

  20. High power quantum cascade lasers

    International Nuclear Information System (INIS)

    We report the most recent state-of-art quantum cascade laser results at wavelengths around 4.8 and 10 μm. At 4.8 μm, a room temperature wall plug efficiency (WPE) of 22 and 15.5% are obtained in pulsed mode and continuous wave (cw) mode, respectively. Room temperature cw output power reaches 3.4 W. The same laser design is able to reach a WPE of 36% at 120 K in pulsed mode. At 10 μm, room temperature average power of 2.2 W and cw power of 0.62 W are obtained. We also explore lasers utilizing the photonic crystal distributed feedback mechanism, and we demonstrate up to 12 W peak power operation at three different wavelengths around 4.7 μm with a waveguide width of 100 μm and diffraction limited beam quality.

  1. Compact Quantum Cascade Laser Transmitter

    Energy Technology Data Exchange (ETDEWEB)

    Anheier, Norman C.; Hatchell, Brian K.; Gervais, Kevin L.; Wojcik, Michael D.; Krishnaswami, Kannan; Bernacki, Bruce E.

    2009-04-01

    ): In this paper we present design considerations, thermal and optical modeling results, and device performance for a ruggedized, compact laser transmitter that utilizes a room temperature quantum cascade (QC) laser source. The QC laser transmitter is intended for portable mid-infrared (3-12 µm) spectroscopy applications, where the atmospheric transmission window is relatively free of water vapor interference and where the molecular rotational vibration absorption features can be used to detect and uniquely identify chemical compounds of interest. Initial QC laser-based sensor development efforts were constrained by the complications of cryogenic operation. However, improvements in both QC laser designs and fabrication processes have provided room-temperature devices that now enable significant miniaturization and integration potential for national security, environmental monitoring, atmospheric science, and industrial safety applications.

  2. External cavity quantum cascade laser

    International Nuclear Information System (INIS)

    In this paper we review the progress of the development of mid-infrared quantum cascade lasers (QCLs) operated in an external cavity configuration. We concentrate on QCLs based on the bound-to-continuum design, since this design is especially suitable for broadband applications. Since they were first demonstrated, these laser-based tunable sources have improved in performance in terms of output power, duty cycle, operation temperature and tuneability. Nowadays they are an interesting alternative to FTIRs for some applications. They operate at room temperature, feature a high spectral resolution while being small in size. They were successfully used in different absorption spectroscopy techniques. Due to their vast potential for applications in industry, medicine, security and research, these sources enjoy increasing interest within the research community as well as in industry. (topical review)

  3. Third Generation in Cascade Decays

    CERN Document Server

    Dutta, Bhaskar; Maxin, James A; Nanopoulos, Dimitri V; Sinha, Kuver; Walker, Joel W

    2014-01-01

    In supersymmetric models with gluinos around 1000-2000 GeV, new physics searches based on cascade decay products of the gluino are viable at the next run of the LHC. We investigate a scenario where the light stop is lighter than the gluino and both are lighter than all other squarks, and show that its signal can be established using multi b-jet, multi W and/or multi lepton final state topologies. We then utilize both boosted and conventional jet topologies in the final state in conjunction with di-tau production as a probe of the stau-neutralino co-annihilation region responsible for the model's dark matter content. This study is performed in the specific context of one such phenomenologically viable model named No-Scale F-SU(5).

  4. Cascades in interdependent flow networks

    Science.gov (United States)

    Scala, Antonio; De Sanctis Lucentini, Pier Giorgio; Caldarelli, Guido; D'Agostino, Gregorio

    2016-06-01

    In this manuscript, we investigate the abrupt breakdown behavior of coupled distribution grids under load growth. This scenario mimics the ever-increasing customer demand and the foreseen introduction of energy hubs interconnecting the different energy vectors. We extend an analytical model of cascading behavior due to line overloads to the case of interdependent networks and find evidence of first order transitions due to the long-range nature of the flows. Our results indicate that the foreseen increase in the couplings between the grids has two competing effects: on the one hand, it increases the safety region where grids can operate without withstanding systemic failures; on the other hand, it increases the possibility of a joint systems' failure.

  5. Cascades in interdependent flow networks

    CERN Document Server

    Scala, Antonio; Caldarelli, Guido; D'Agostino, Gregorio

    2015-01-01

    We investigate the abrupt breakdown behavior of coupled distribution grids under load growth. This scenario mimics the ever-increasing customer demand and the foreseen introduction of energy hubs interconnecting the different energy vectors. We extend an analytical model of cascading behavior due to line overloads to the case of interdependent networks and find evidence of first order transitions due to the long-range nature of the flows. Our results indicate that the foreseen increase in the couplings between the grids has two competing effects: on the one hand, it increases the safety region where grids can operate without withstanding systemic failures; on the other hand, it increases the possibility of a joint systems' failure.

  6. The Geant4 Bertini Cascade

    Energy Technology Data Exchange (ETDEWEB)

    Wright, D. H.; Kelsey, M. H.

    2015-12-01

    One of the medium energy hadron–nucleus interaction models in the Geant4 simulation toolkit is based partly on the Bertini intranuclear cascade model. Since its initial appearance in the toolkit, this model has been largely re-written in order to extend its physics capabilities and to reduce its memory footprint. Physics improvements include extensions in applicable energy range and incident particle types, and improved hadron–nucleon cross-sections and angular distributions. Interfaces have also been developed which allow the model to be coupled with other Geant4 models at lower and higher energies. The inevitable speed reductions due to enhanced physics have been mitigated by memory and CPU efficiency improvements. Details of these improvements, along with selected comparisons of the model to data, are discussed.

  7. Inverse cascades of angular momentum

    International Nuclear Information System (INIS)

    Most theoretical and computational studies of turbulence in Navier-Stokes fluids and/or guiding-centre plasmas have been carried out in the presence of spatially periodic boundary conditions. In view of the frequently reproduced result that two-dimensional and/or MHD decaying turbulence leads to structures comparable in length scae to a box dimension, it is natural to ask if periodic boundary conditions are an adequate representation of any physical situation. Here, we study, computationally, the decay of two-dimensional turbulence in a Navier-Stokes fluid or guiding-centre plasma in the presence of circular no-slip rigid walls. The method is wholly spectral, and relies on a Galerkin approximation by a set of functions that obey two boundary conditions at the wall radius (analogues of the Chandrasekhar-Reid functions). It is possible to explore Reynolds numbers up to the order of 1250, based on an RMS velocity and a box radius. It is found that decaying turbulence is altered significantly by the no-slip boundaries. First, strong boundary layers serve as sources of vorticity and enstrophy and enhance the early-time energy decay rate, for a given Reynolds number, well above the periodic boundary condition values. More importantly, angular momentum turns out to be an even more slowly decaying ideal invariant than energy, and to a considerable extent governs the dynamics of the decay. Angular momentum must be taken into account, for example, in order to achieve quantitative agreement with the prediction of maximum entropy, or 'most probable', states. These are predictions of conditions that are established after several eddy turnover times but before the energy has decayed away. Angular momentum will cascade to lower azimuthal mode numbers, even if absent there initially, and the angular momentum modal spectrum is eventually dominated by the lowest mode available. When no initial angular momentum is present, no behaviour that suggests the likelihood of inverse cascades

  8. Modelling faecal coliform mortality in water hyacinths ponds

    Science.gov (United States)

    Mayo, A. W.; Kalibbala, M.

    Removal of faecal coliforms was investigated in pilot-scale water hyacinths ponds. The investigation was conducted to evaluate the role of solar intensity, pH, dissolved oxygen, temperature, sedimentation, and attachment of faecal coliforms on Eichhornia crassipes on disappearance of bacteria in water hyacinths ponds. A mathematical model that used the plug flow philosophy and incorporating the aforementioned factors was developed to predict faecal coliform mortality rate. The proposed multifactor model satisfactorily predicted mortality rate of faecal coliforms in a pilot-scale water hyacinths ponds. After optimization of the parameters, mortality rate constant for pH ( kpH) was 0.001, mortality rate constant for DO ( kDO) was 0.0037 and solar intensity mortality rate constant k s was 0.0102 cm 2/cal. The results also showed that the thickness of biofilm ( Lf) was 2.5 × 10 -4 m, and the effective surface area of water hyacinths roots per unit surface area of pond ( Rs) was 10.4 m 2/m 2. The results further showed that environmental factors such as solar intensity and pH were the key factors when water hyacinths ponds have a large exposed surface area. However, attachment of bacteria to water hyacinths played a major role in ponds fully covered with water hyacinths. The inclusion of sedimentation parameters in the model improved model efficiency by only 3.2%. It was concluded that sedimentation is not a major factor governing faecal coliform disappearance in water hyacinths pond systems receiving pretreated wastewaters.

  9. Par Pond vegetation status Summer 1995 -- June survey descriptive summary

    International Nuclear Information System (INIS)

    The water level of Par Pond was lowered approximately 20 feet in mid-1991 in order to protect downstream residents from possible dam failure suggested by subsidence on the downstream slope of the dam and to repair the dam. This lowering exposed both emergent and nonemergent macrophyte beds to drying conditions resulting in extensive losses. A survey of the shoreline aquatic plant communities in June 1995, three months after the refilling of Par Pond to approximately 200 feet above mean sea level, indicated that much of the original plant communities and the intermediate shoreline communities present on the exposed sediments have been lost. The extensive old-field and emergent marsh communities that were present on the exposed shoreline during the drawdown have been flooded and much of the pre-drawdown Par Pond aquatic plant communities have not had sufficient time for re-establishment. The shoreline does, however, have extensive beds of maidencane which extend from the shoreline margin to areas as deep as 2 and perhaps 3 meters. Scattered individual plants of lotus and watershield are common and may indicate likely directions of future wetland development in Par Pond. In addition, within isolated coves, which apparently received ground water seepage and/or stream surface flows during the period of the Par Pond draw down, extensive beds of waterlilies and spike rush are common. Invasion of willow and red maple occurred along the lake shoreline as well. Although not absent from this survey, evidence of the extensive redevelopment of the large cattail and eel grass beds was not observed in this first survey of Par Pond. Future surveys during the growing seasons of 1995, 1996, and 1997 along with the evaluation of satellite date to map the areal extent of the macrophyte beds of Par Pond are planned

  10. Design and Application of a Solar Mobile Pond Aquaculture Water Quality-Regulation Machine Based in Bream Pond Aquaculture.

    Directory of Open Access Journals (Sweden)

    Xingguo Liu

    Full Text Available Bream pond aquaculture plays a very important role in China's aquaculture industry and is the main source of aquatic products. To regulate and control pond water quality and sediment, a movable solar pond aquaculture water quality regulation machine (SMWM was designed and used. This machine is solar-powered and moves on water, and its primary components are a solar power supply device, a sediment lifting device, a mechanism for walking on the water's surface and a control system. The solar power supply device provides power for the machine, and the water walking mechanism drives the machine's motion on the water. The sediment lifting device orbits the main section of the machine and affects a large area of the pond. Tests of the machine's mechanical properties revealed that the minimum illumination necessary for the SMWM to function is 13,000 Lx and that its stable speed on the water is 0.02-0.03 m/s. For an illumination of 13,000-52,500 Lx, the sediment lifting device runs at 0.13-0.35 m/s, and its water delivery capacity is 110-208 m(3/h. The sediment lifting device is able to fold away, and the angle of the suction chamber can be adjusted, making the machine work well in ponds at different water depths from 0.5 m to 2 m. The optimal distance from the sediment lifting device to the bottom of the pond is 10-15 cm. In addition, adjusting the length of the connecting rod and the direction of the traction rope allows the SMWM to work in a pond water area greater than 80%. The analysis of water quality in Wuchang bream (Parabramis pekinensis and silver carp (Hypophthalmichthys molitrix culture ponds using the SMWM resulted in decreased NH3(+-N and available phosphorus concentrations and increased TP concentrations. The TN content and the amount of available phosphorus in the sediment were reduced. In addition, the fish production showed that the SMWM enhanced the yields of Wuchang bream and silver carp by more than 30% and 24%, respectively. These

  11. Design and Application of a Solar Mobile Pond Aquaculture Water Quality-Regulation Machine Based in Bream Pond Aquaculture.

    Science.gov (United States)

    Liu, Xingguo; Xu, Hao; Ma, Zhuojun; Zhang, Yongjun; Tian, Changfeng; Cheng, Guofeng; Zou, Haisheng; Lu, Shimin; Liu, Shijing; Tang, Rong

    2016-01-01

    Bream pond aquaculture plays a very important role in China's aquaculture industry and is the main source of aquatic products. To regulate and control pond water quality and sediment, a movable solar pond aquaculture water quality regulation machine (SMWM) was designed and used. This machine is solar-powered and moves on water, and its primary components are a solar power supply device, a sediment lifting device, a mechanism for walking on the water's surface and a control system. The solar power supply device provides power for the machine, and the water walking mechanism drives the machine's motion on the water. The sediment lifting device orbits the main section of the machine and affects a large area of the pond. Tests of the machine's mechanical properties revealed that the minimum illumination necessary for the SMWM to function is 13,000 Lx and that its stable speed on the water is 0.02-0.03 m/s. For an illumination of 13,000-52,500 Lx, the sediment lifting device runs at 0.13-0.35 m/s, and its water delivery capacity is 110-208 m(3)/h. The sediment lifting device is able to fold away, and the angle of the suction chamber can be adjusted, making the machine work well in ponds at different water depths from 0.5 m to 2 m. The optimal distance from the sediment lifting device to the bottom of the pond is 10-15 cm. In addition, adjusting the length of the connecting rod and the direction of the traction rope allows the SMWM to work in a pond water area greater than 80%. The analysis of water quality in Wuchang bream (Parabramis pekinensis) and silver carp (Hypophthalmichthys molitrix) culture ponds using the SMWM resulted in decreased NH3(+)-N and available phosphorus concentrations and increased TP concentrations. The TN content and the amount of available phosphorus in the sediment were reduced. In addition, the fish production showed that the SMWM enhanced the yields of Wuchang bream and silver carp by more than 30% and 24%, respectively. These results

  12. Par Pond vegetation status Summer 1995 -- October survey descriptive summary

    International Nuclear Information System (INIS)

    The water level of Par Pond was lowered approximately 20 feet in mid-1991 in order to protect downstream residents from possible dam failure suggested by subsidence on the downstream slope of the dam and to repair the dam. This lowering exposed both emergent and nonemergent macrophyte beds to drying conditions resulting in extensive losses. A survey of the emergent shoreline aquatic plant communities began in June 1995, three months after the refilling of Par Pond to approximately 200 feet above mean sea level and continued with this late October survey. Communities similar to the pre-drawdown Par Pond aquatic plant communities are becoming re-established; especially, beds of maiden cane, lotus, waterlily, and watershield are now extensive and well established. Cattail occurrence continues to increase, but large beds common to Par Pond prior to the drawdown have not formed. Future surveys throughout 1996 and 1997, along with the continued evaluation of satellite data to map the areal extent of the macrophyte beds of Par Pond, are planned

  13. Par Pond vegetation status Summer 1995 -- September survey descriptive summary

    International Nuclear Information System (INIS)

    The water level of Par Pond was lowered approximately 20 feet in mid-1991 in order to protect downstream residents from possible dam failure suggested by subsidence on the downstream slope of the dam and to repair the dam. This lowering exposed both emergent and nonemergent macrophyte beds to drying conditions resulting in extensive losses. A survey of the emergent shoreline aquatic plant communities began in June 1995, three months after the refilling of Par Pond to approximately 200 feet above mean sea level and continued with this mid-September survey. Communities similar to the pre-drawdown Par Pond aquatic plant communities are becoming re-established; especially, beds of maidencane, lotus, waterlily, and watershield are now extensive and well established. Cattail occurrence continues to increase, but large beds common to Par Pond prior to the drawdown have not formed. Future surveys during the late growing seasons of 1995, and throughout 1996 and 1997, along with the evaluation of satellite data to map the areal extent of the macrophyte beds of Par Pond, are planned

  14. Biogeochemistry of dimethylsulfide in a seasonally stratified coastal salt pond

    Science.gov (United States)

    Wakeham, S. G.; Howes, B. L.; Dacey, J. W. H.; Schwarzenbach, R. P.; Zeyer, J.

    1987-01-01

    Dimethylsulfide (DMS) is the major volatile reduced organic sulfur compound in the water column of coastal Salt Pond, Cape Cod, MA. DMS concentration and vertical distributions vary seasonally in response to changing biogeochemical processes in the pond. When the pond is thermally stratified in summer, maximum DMS concentrations of up to 60 nmol/l were found in the oxygen-deficient metalimnion. DMS concentrations in the epilimnion (typically 5-10 nmol/l) were always an order of magnitude higher than in the hypolimnion (less than 0.2 nmol/l). The most likely precursor for DMS is algal dimethylsulfoniopropionate (DMSP), which showed vertical profiles similar to those of DMS. Laboratory experiments show that microorganisms in the pond, especially in the metalimnion, are capable of decomposing DMSP to DMS, while photosynthetic sulfur bacteria in the hypolimnion can consume DMS. Estimates of DMS production and consumption in Salt Pond have been made, considering production of DMS in the epilimnion and metalimnion and removal of DMS via gas exchange to the atmosphere, tidal exchange, and microbial consumption in the hypolimnion.

  15. Revegetation of flue gas desulfurization sludge pond disposal sites

    International Nuclear Information System (INIS)

    A comprehensive search of published literature was conducted to summarize research undertaken to date on revegetation of flue gas desulfurization (FGD) waste disposal ponds. A review of the physical and chemical properties of FGD sludges and wastes with similar characteristics is also included in order to determine the advantages and limitations of FGD sludge for plant growth. No specific guidelines have been developed for the revegetation of FGD sludge disposal sites. Survey studies showed that the wide-ranging composition of FGD wastes was determined primarily by the sulfur dioxide and other flue gas scrubbing processes used at powerplants. Sulfate rich (>90%CaSO4) FGD sludges are physically and chemically more stable, and thus more amenable to revegetation. Because of lack of macronutrients and extremely limited microbial activity, FBD sludge ponds presented a poor plant growth environment without amendment. Studies showed the natural process of inoculation of the FGD sludge with soil microbes that promote plant growth be can after disposal but proceeded slowly. Revegetation studies reviewed showed that FGD sludges amended with soils supported a wider variety of plant species better and longer than abandoned FGD ponds. Two major types of plants have been successful in revegetation of FGD waste ponds and similar wastes: salt-tolerant plants and aquatic plants. A comprehensive list of plant species with potential for regetation of FGD sludge disposal pond sites is presented along with successful revegetation techniques

  16. Genetic algorithm based separation cascade optimization

    International Nuclear Information System (INIS)

    The conventional separation cascade design procedure does not give an optimum design because of squaring-off, variation of flow rates and separation factor of the element with respect to stage location. Multi-component isotope separation further complicates the design procedure. Cascade design can be stated as a constrained multi-objective optimization. Cascade's expectation from the separating element is multi-objective i.e. overall separation factor, cut, optimum feed and separative power. Decision maker may aspire for more comprehensive multi-objective goals where optimization of cascade is coupled with the exploration of separating element optimization vector space. In real life there are many issues which make it important to understand the decision maker's perception of cost-quality-speed trade-off and consistency of preferences. Genetic algorithm (GA) is one such evolutionary technique that can be used for cascade design optimization. This paper addresses various issues involved in the GA based multi-objective optimization of the separation cascade. Reference point based optimization methodology with GA based Pareto optimality concept for separation cascade was found pragmatic and promising. This method should be explored, tested, examined and further developed for binary as well as multi-component separations. (author)

  17. The Influence of Micropore Oxygen Aeration on the Pond Water Quality Environment

    Directory of Open Access Journals (Sweden)

    Xiao-Jiang Chen

    2013-11-01

    Full Text Available In order to know the effects of micropore oxygen aeration on the water quality and economic output, take each 3 of micropore oxygen aeration (experimental pond and impeller oxygenation (control pond to make the comparison, indexs of two different aeration methods water were detected from May, 2012 to October, 2012. Such as water temperature, dissolved oxygen, ammonia nitrogen and nitrite, phytoplankton, chemical oxygen demand (CODMn. Results showed that, (1 the indexes of the dissolved oxygen, ammonia nitrogen, chemical oxygen demand(CODMn and nitrite of the experimental pond are all superior to that of the control pond, of which the concentration of the dissolved oxygen of the experimental pond is 8.37 mg/L which is higher than that of the control pond (5.7 mg/L. And, (CODMn in the experimental pond is 7.54 mg/L, lower than that in the control pond (10.19 mg/L. The difference between the control pond and the experimental pond was statistically significant (p<0.01. The ammonia nitrogen of the experimental pond is 0.1 mg/L, obviously lower than the control pond (0.16 mg/L. Besides, the nitrite is 0.13 mg/L in the experimental pond, lower than that of the control pond (0.21 mg/L. (2 Compared with the control pond, the experimental pond has quite higher general abundance of algae, with about 5.69×108 ind/L. Yet, there is no obvious difference between them. (3 Compared to the impeller oxygenation, the micropore oxygen aeration technology can be better to increase the dissolved oxygen in the aquaculture pond and improve the water quality. However, there is no significant influence to the phytoplankton abundance and diversity.

  18. Thermal compressor of cascade exchange by pressure

    Directory of Open Access Journals (Sweden)

    Aleksander KRAJNIUK

    2010-01-01

    Full Text Available A new method of organization of working cycle of device of direct transformation of heat in the located work of compression of air, based on principle of cascade exchange by pressure, is exposed; the results of pre-selection of basic dimensional and structural parameters of thermal compressor of cascade exchange by pressure are adduced; some special features of its working process are considered; main directions of perfection of working cycle of thermal compressors of cascade exchange of pressure are shown.

  19. Cascades on clique-based graphs

    Science.gov (United States)

    Hackett, Adam; Gleeson, James P.

    2013-06-01

    We present an analytical approach to determining the expected cascade size in a broad range of dynamical models on the class of highly clustered random graphs introduced by Gleeson [J. P. Gleeson, Phys. Rev. EPLEEE81539-375510.1103/PhysRevE.80.036107 80, 036107 (2009)]. A condition for the existence of global cascades is also derived. Applications of this approach include analyses of percolation, and Watts's model. We show how our techniques can be used to study the effects of in-group bias in cascades on social networks.

  20. Lime application methods, water and bottom soil acidity in fresh water fish ponds

    Directory of Open Access Journals (Sweden)

    Queiroz Julio Ferraz de

    2004-01-01

    Full Text Available Although some methods for determining lime requirement of pond soils are available and commonly used, there is still no consensus on whether it is more effective to apply liming materials to the bottoms of empty ponds or to wait and apply them over the water surface after ponds are filled. There is also little information on how deep lime reacts in pond sediment over time, and whether the depth of reaction is different when liming materials are applied to the water or to the soil. Therefore, three techniques for treating fish ponds with agricultural limestone were evaluated in ponds with clayey soils at a commercial fish farm. Amounts of agricultural limestone equal to the lime requirement of bottom soils were applied to each of three ponds by: direct application over the pond water surface; spread uniformly over the bottom of the empty pond; spread uniformly over the bottom of the empty pond followed by tilling of the bottom. Effectiveness of agricultural limestone applications did not differ among treatment methods. Agricultural limestone also reacted quickly to increase total alkalinity and total hardness of pond water to acceptable concentrations within 2 weeks after application. The reaction of lime to increase soil pH was essentially complete after one to two months, and lime had no effect below a soil depth of 8 cm. Tilling of pond bottoms to incorporate liming materials is unnecessary, and tilling consumes time and is an expensive practice; filled ponds can be limed effectively.

  1. Common carp (Cyprinus carpio L.) alters its feeding niche in response to changing food resources: direct observations in simulated ponds

    OpenAIRE

    Rahman, M.M.; Kadowaki, S.; Balcombe, S.R.; Wahab, M.A.

    2010-01-01

    We used customized fish tanks as model fish ponds to observe grazing, swimming, and conspecific social behavior of common carp (Cyprinus carpio) under variable food-resource conditions to assess alterations in feeding niche. Different food and feeding situations were created by using only pond water or pond water plus pond bottom sediment or pond water plus pond bottom sediment and artificial feeding. All tanks were fertilized twice, prior to stocking and 2 weeks later after starting the expe...

  2. Liner selection for the El Paso Solar Pond

    International Nuclear Information System (INIS)

    The El Paso Solar Pond has been operating as a research, development and demonstration project for ten years. The importance of the project's desalination technologies and electric power generation are described in a previous paper. The importance of the project as a means of disposal of brines generated by oil and gas production have also been described. The El Paso Solar Pond recently experienced a complete failure of its XR-5 8130 (SP) liner. In its place a multi-layered clay and plastic-film liner will be installed. This paper will summarize the XR-5 8130 (SP) liner failure analysis and provide preliminary results from laboratory experiments on a clay and plastic-film liner to determine its suitability for use in the new 3350 square meter El Paso Solar Pond. Heat and moisture transport characteristics of the clay-plastic liner will be investigated. An effective thermal conductivity which includes the effect of vapor transport will be investigated experimentally

  3. Stability of the dam at the Sillamaee tailings pond

    International Nuclear Information System (INIS)

    The tailings pond at Sillamaee is contained by a dam located 30 to 50 meters from the waters of the Baltic Sea. The tailings pond was begun in the 1950s, at which time the height of the dam was 12 m. It has been increased since then to 25 m. The apparently realtively unplanned buildup of the dam and lack of maintenance have led to a decrease in the stability of the dam. In its present conditions, the dam of the tailings pond is less stable than is recommended by international practice. Estonian, Norwegian, Swedish, and Finnish specialists have investigated various aspects of the dam's stability. This paper summarizes their findings and makes recommendations for further work

  4. Radiatively-driven convection in melt ponds on sea ice

    Science.gov (United States)

    Wells, Andrew; Moon, Woosok; Rees Jones, David; Kim, Joo-Hong; Wilkinson, Jeremy

    2016-04-01

    Melt ponds have a significant impact on the energy budget of sea ice, and the predictability of the evolving summer sea ice cover. Recent observations of melt-pond temperature show complex vertical structure, with significant diurnal variability. To understand the driving physical mechanisms, we use two-dimensional direct numerical simulations of turbulent convection in a relatively fresh melt pond. We quantify the competition between internal radiative heating and surface fluxes in controlling the strength of convective flow. We explore variability in the resulting energy balance for a range of forcing, including effects of the diurnal cycle. The results are evaluated in light of the strong sensitivity of sea-ice thickness to net energy flux perturbations of order of a few watts per square metre.

  5. Groundwater and contaminant transport modelling at the Sydney Tar Ponds

    Energy Technology Data Exchange (ETDEWEB)

    King, M. [Groundwater Insight Inc., Halifax, NS (Canada); Check, G. [Jacques Whitford Environment Ltd., Halifax, NS (Canada); Carey, G. [Environmental Inst. for Continuing Education, Waterloo, ON (Canada); Abbey, D. [Waterloo Hydrogeologic, Waterloo, ON (Canada); Baechler, F. [ADI Ltd., Sydney, NS (Canada)

    2003-07-01

    The Muggah Creek Watershed, a tidal estuary located in Sydney, Nova Scotia, is known locally as the Tar Ponds. Over the past century, the Tar Ponds have accumulated contaminants in the contributing watershed from the iron, steel and coke manufacturing. There are sediments contaminated with polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs). A groundwater modelling program was developed to estimate current contaminant fluxes to the estuary and site streams, through groundwater. Attempts were made to incorporate a complex stratigraphic profile, where groundwater flow and contaminant transport is strongly controlled by shallow fractured bedrock, into the conceptual model developed for the site. This conceptual model for groundwater flow and contaminant transport at the Sydney Tar Ponds site was presented. The complex flow patterns between bedrock and overburden, and between the bedrock units and surface water bodies were illustrated with model simulations. It was found that groundwater flow was dominated by discharge to the streams and the estuary. 6 refs., 2 tabs., 11 figs.

  6. Performance of municipal waste stabilization ponds in the Canadian Arctic

    DEFF Research Database (Denmark)

    Ragush, Colin M.; Schmidt, Jordan J.; Krkosek, Wendy H.;

    2015-01-01

    The majority of small remote communities in the Canadian arctic territory of Nunavut utilize waste stabilization ponds (WSPs) for municipal wastewater treatment because of their relatively low capital and operational costs, and minimal complexity. New national effluent quality regulations have been...... implemented in Canada, but not yet applied to Canada’s Arctic due to uncertainty related to the performance of current wastewater treatment systems. Waste stabilization pond (WSP) treatment performance is impacted by community water use, pond design, and climate. The greatest challenge arctic communities...... experience when using passive wastewater treatment technologies is the constraints imposed by the extreme climate, which is characterized as having long cold winters with short cool summers that can be solar intense. The removal of carbonaceous biochemical oxygen demand (CBOD5), total suspended solids (TSS...

  7. Role of livestock effluent suspended particulate in sealing effluent ponds.

    Science.gov (United States)

    Bennett, J McL; Warren, B R

    2015-05-01

    Intensive livestock feed-lots have become more prevalent in recent years to help in meeting the predicted food production targets based on expected population growth. Effluent from these is stored in ponds, representing a potential concern for seepage and contamination of groundwater. Whilst previous literature suggests that effluent particulate can limit seepage adequately in combination with a clay liner, this research addresses potential concerns for sealing of ponds with low concentration fine and then evaluates this against proposed filter-cake based methodologies to describe and predict hydraulic reduction. Short soil cores were compacted to 98% of the maximum dry density and subject to ponded head percolation with unfiltered-sediment-reduced effluent, effluent filtered to sealing was shown to follow mathematical models of filter-cake formation, but without the formation of a physical seal on top of the soil surface. Management considerations based on the results are presented. PMID:25721977

  8. Garden ponds as potential introduction pathway of ornamental crayfish

    Directory of Open Access Journals (Sweden)

    Patoka J.

    2014-01-01

    Full Text Available The private stocking of ornamental crayfish in garden ponds was discussed in previous studies, but there is a lack of detailed analysis for better understanding of this introduction pathway. The Czech Republic is one of leading EU countries in trade with ornamental crayfish and private garden ponds are popular among people. The crayfish keepers in the country were interviewed by self-administered questionnaire to gather data about principal characteristics of the keepers and detailed information about crayfish breeding that are of interest for conservation managers. Besides of releasing crayfish into garden ponds, alarming illegal behavior such as releasing of juvenile crayfish into the wild, and capturing of indigenous crayfish from wild populations, were registered. Therefore focusing on public education to increase awareness of possible unwanted consequences of crayfish release and introduction of an obligation to inform customers about hazardousness of non-indigenous crayfish species for retailers and wholesalers is recommended.

  9. Cascade-able spin torque logic gates with input-output isolation

    Science.gov (United States)

    Nikonov, Dmitri E.; Manipatruni, Sasikanth; Young, Ian A.

    2015-06-01

    Spin torque majority gate (STMG) is one of the promising options for beyond-complementary metal-oxide-semiconductor non-volatile logic circuits for normally-off computing. Modeling of prior schemes demonstrated logic completeness using majority operation and nonlinear transfer characteristics. However significant problems arose with cascade-ability and input output isolation manifesting as domain walls (DWs) stopping, reflecting off ends of wires or propagating back to the inputs. We introduce a new scheme to enable cascade-ability and isolation based on (a) in-plane DW automotion in interconnects, (b) exchange coupling of magnetization between two FM layers, and (c) ‘round-about’ topology for the majority gate. We performed micro-magnetic simulations that demonstrate switching operation of this STMG scheme. These circuits were verified to enable isolation of inputs from output signals and to be cascade-able without limitations.

  10. Embankment over fly ash pond at Portsmouth Power Station

    International Nuclear Information System (INIS)

    The fly ash and bottom ash sediments from the Portsmouth Power Station in Portsmouth, Virginia were being sluiced into a 39 acre diked ash pond near the plant. When the ash level within the pond was an average of 4 feet below the crest of the dike, it was decided to enlarge the capacity of the disposal area. The plant was about to convert to dry ash disposal, and thus, the plan was to construct a 30-foot high fly ash embarkment over the previously ponded ash. To meet regulatory guidelines, the conversion from wet to dry disposal of fly ash required that the existing ''wet'' pond area be ''closed'' with an impermeable cover and that the new ''dry'' area have an impervious liner (a cover-liner system). This posed potential drainage constraints necessitating an underdrain system below the cover-liner system. The design had to address the stability of the new 30-foot ash embankment constructed over confined, saturated ponded ash and not adversely affect the stability of the perimeter dike. The design also had to provide for interim storage of sluiced fly ash, which resulted in a new inner perimeter dike (inside the existing main dike) and for long term storage for sluiced bottom ash. The sluiced bottom ash would be collected in a small segmented diked pond within the existing main dike. This paper describes the subsurface exploration, stability evaluation, underdrains, design, instrumentation results, and problems encountered during construction of this converted disposal area which extended the life of the facility a minimum of five years

  11. Carbon dynamics in highly heterotrophic subarctic thaw ponds

    Directory of Open Access Journals (Sweden)

    T. Roiha

    2015-07-01

    Full Text Available Global warming has accelerated the formation of permafrost thaw ponds in several subarctic and arctic regions. These ponds are net heterotrophic as evidenced by their greenhouse gas (GHG supersaturation levels (CO2 and CH4, and generally receive large terrestrial carbon inputs from the thawing and eroding permafrost. We measured seasonal and vertical variations in the concentration and type of dissolved organic matter (DOM in five subarctic thaw (thermokarst ponds in northern Quebec, and explored how environmental gradients influenced heterotrophic and phototrophic biomass and productivity. Late winter DOM had low aromaticity indicating reduced inputs of terrestrial carbon, while the high concentration of dissolved organic carbon (DOC suggests that some production of non-chromophoric dissolved compounds by the microbial food web took place under the ice cover. Summer DOM had a strong terrestrial signature, but was also characterized with significant inputs of algal-derived carbon, especially at the pond surface. During late winter, bacterial production was low (maximum of 0.8 mg C m−3 d−1 and was largely based on free-living bacterioplankton (58 %. Bacterial production in summer was high (up to 58 mg C m−3 d−1, dominated by particle-attached bacteria (67 %, and strongly correlated to the amount of terrestrial carbon. Primary production was restricted to summer surface waters due to strong light limitation deeper in the water column or in winter. The phototrophic biomass was equal to the heterotrophic biomass, but as the algae were mostly composed of mixotrophic species, most probably they used bacteria rather than solar energy in such shaded ponds. According to the δ13C analyses, non-algal carbon supported 51 % of winter and 37 % of summer biomass of the phantom midge larvae, Chaoborus sp., that are at the top of the trophic chain. Our results point to a strong heterotrophic energy pathway in these thaw pond ecosystems, where

  12. Carbon dynamics in highly heterotrophic subarctic thaw ponds

    Science.gov (United States)

    Roiha, T.; Laurion, I.; Rautio, M.

    2015-07-01

    Global warming has accelerated the formation of permafrost thaw ponds in several subarctic and arctic regions. These ponds are net heterotrophic as evidenced by their greenhouse gas (GHG) supersaturation levels (CO2 and CH4), and generally receive large terrestrial carbon inputs from the thawing and eroding permafrost. We measured seasonal and vertical variations in the concentration and type of dissolved organic matter (DOM) in five subarctic thaw (thermokarst) ponds in northern Quebec, and explored how environmental gradients influenced heterotrophic and phototrophic biomass and productivity. Late winter DOM had low aromaticity indicating reduced inputs of terrestrial carbon, while the high concentration of dissolved organic carbon (DOC) suggests that some production of non-chromophoric dissolved compounds by the microbial food web took place under the ice cover. Summer DOM had a strong terrestrial signature, but was also characterized with significant inputs of algal-derived carbon, especially at the pond surface. During late winter, bacterial production was low (maximum of 0.8 mg C m-3 d-1) and was largely based on free-living bacterioplankton (58 %). Bacterial production in summer was high (up to 58 mg C m-3 d-1), dominated by particle-attached bacteria (67 %), and strongly correlated to the amount of terrestrial carbon. Primary production was restricted to summer surface waters due to strong light limitation deeper in the water column or in winter. The phototrophic biomass was equal to the heterotrophic biomass, but as the algae were mostly composed of mixotrophic species, most probably they used bacteria rather than solar energy in such shaded ponds. According to the δ13C analyses, non-algal carbon supported 51 % of winter and 37 % of summer biomass of the phantom midge larvae, Chaoborus sp., that are at the top of the trophic chain. Our results point to a strong heterotrophic energy pathway in these thaw pond ecosystems, where bacterioplankton dominates

  13. A holistic water depth simulation model for small ponds

    Science.gov (United States)

    Ali, Shakir; Ghosh, Narayan C.; Mishra, P. K.; Singh, R. K.

    2015-10-01

    Estimation of time varying water depth and time to empty of a pond is prerequisite for comprehensive and coordinated planning of water resource for its effective utilization. A holistic water depth simulation (HWDS) and time to empty (TE) model for small, shallow ephemeral ponds have been derived by employing the generalized model based on the Green-Ampt equation in the basic water balance equation. The HWDS model includes time varying rainfall, runoff, surface water evaporation, outflow and advancement of wetting front length as external inputs. The TE model includes two external inputs; surface water evaporation and advancement of wetting front length. Both the models also consider saturated hydraulic conductivity and fillable porosity of the pond's bed material as their parameters. The solution of the HWDS model involved numerical iteration in successive time intervals. The HWDS model has successfully evaluated with 3 years of field data from two small ponds located within a watershed in a semi-arid region in western India. The HWDS model simulated time varying water depth in the ponds with high accuracy as shown by correlation coefficient (R2 ⩾ 0.9765), index of agreement (d ⩾ 0.9878), root mean square errors (RMSE ⩽ 0.20 m) and percent bias (PB ⩽ 6.23%) for the pooled data sets of the measured and simulated water depth. The statistical F and t-tests also confirmed the reliability of the HWDS model at probability level, p ⩽ 0.0001. The response of the TE model showed its ability to estimate the time to empty the ponds. An additional field calibration and validation of the HWDS and TE models with observed field data in varied hydro-climatic conditions could be conducted to increase the applicability and credibility of the models.

  14. Quantum Cascade Laser Frequency Combs

    Science.gov (United States)

    Faist, Jérôme; Villares, Gustavo; Scalari, Giacomo; Rösch, Markus; Bonzon, Christopher; Hugi, Andreas; Beck, Mattias

    2016-06-01

    It was recently demonstrated that broadband quantum cascade lasers can operate as frequency combs. As such, they operate under direct electrical pumping at both mid-infrared and THz frequencies, making them very attractive for dual-comb spectroscopy. Performance levels are continuously improving, with average powers over 100mW and frequency coverage of 100 cm-1 in the mid-infrared region. In the THz range, 10mW of average power and 600 GHz of frequency coverage are reported. As a result of the very short upper state lifetime of the gain medium, the mode proliferation in these sources arises from four-wave mixing rather than saturable absorption. As a result, their optical output is characterized by the tendency of small intensity modulation of the output power, and the relative phases of the modes to be similar to the ones of a frequency modulated laser. Recent results include the proof of comb operation down to a metrological level, the observation of a Schawlow-Townes broadened linewidth, as well as the first dual-comb spectroscopy measurements. The capability of the structure to integrate monothically nonlinear optical elements as well as to operate as a detector shows great promise for future chip integration of dual-comb systems.

  15. Quantum Cascade Laser Frequency Combs

    CERN Document Server

    Faist, Jérôme; Scalari, Giacomo; Rösch, Markus; Bonzon, Christopher; Hugi, Andreas; Beck, Mattias

    2015-01-01

    It was recently demonstrated that broadband quantum cascade lasers can operate as frequency combs. As such, they operate under direct electrical pumping at both mid-infrared and THz frequencies, making them very attractive for dual-comb spectroscopy. Performance levels are continuously improving, with average powers over 100 mW and frequency coverage of 100 cm$^{-1}$ in the mid-infrared. In the THz range, 10 mW of average power and 600 GHz of frequency coverage are reported. As a result of the very short upper state lifetime of the gain medium, the mode proliferation in these sources arises from four wave mixing rather than saturable absorption. As a result, their optical output is characterized by the tendency of small intensity modulation of the output power, and the relative phases of the modes to be similar to the ones of a frequency modulated laser. Recent results include the proof of comb operation down to a metrological level, the observation of a Schawlow-Townes broadened linewidth, as well as the fir...

  16. Aspects of the QCD cascade

    International Nuclear Information System (INIS)

    A model is proposed for the production of transverse jets from diffractively excited protons. We propose that transverse jets can be obtained from gluonic bremsstrahlung in a way similar to the emission in DIS. Qualitative agreement is obtained between the model and the uncorrected data published by the UA8 collaboration. Perturbative QCD in the MLLA approximation is applied to multiple jet production in e+e--annihilation. We propose modified evolution equations for deriving the jet cross sections, defined in the 'kt' or 'Durham' algorithm. The mean number of jets as a function of the jet resolution is studied, and analytical predictions are compared to the results of MC simulations. We also study a set of differential-difference equations for multiplicity distributions in e+e--annihilations, supplemented with appropriate boundary conditions. These equations take into account nonsingular terms in the GLAP splitting functions as well as kinematical constraints related to recoil effects. The presence of retarded terms imply that the cascade develops more slowly and reduces the fluctuations. The solutions agree well with MC simulations and experimental data. (authors)

  17. South Bay Salt Pond initial stewardship plan & related Bay Area restoration projects

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The Initial Stewardship Plan for the South Bay Salt Pond Restoration Project outlines a process to reduce the salinity of the existing salt ponds and to manage the...

  18. Environmental contaminants in the aquatic bird food chain of an oil refinery wastewater pond in Wyoming

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Petroleum Hydrocarbons Based on higher PAH levels in sediment and vegetation, one would expect Pond 1 to pose a greater risk to wildlife than Pond 2. However, in...

  19. Cladocera of the pond area between Studenka and Polanka in Poodri Landscape Protected Area

    International Nuclear Information System (INIS)

    Poodri Protected Landscape Area was established in 1991, to preserve the Odra River flood plain with many ponds and pools. 32 Cladoceran taxa were identified in samples from the pond area between Studenka and Polanka. (author)

  20. DNR 100K Lakes - Fishing in the Neighborhood (FiN) Ponds

    Data.gov (United States)

    Minnesota Department of Natural Resources — This layer represents ponds included in DNR's Fishing in the Neighborhood (FiN) program. This program establishes local ponds to provide urban fishing opportunities...

  1. Valuating Ecosystem Services of Urban Ponds - case study from Bangladesh

    Science.gov (United States)

    Carle, Nina

    2016-04-01

    A climate risk assessment for the city of Barisal was carried out by a consultancy firm, financed by KfW Development Bank of Germany. Due to high dependencies on natural capital of people in developing countries they are facing high vulnerability when it comes to changes of the asset category 'natural capital' (here: urban ponds), whether due to the exposition on climate (change) related impacts, implemented measures or land use change. With a closer view on the city's assets, the question remained open to the author 1) Under current conditions, what is the demand for ecosystem services (ES) 2) What is the value of the benefits and the how much is the contribution to the city's welfare? 3) What are the future changes in the demand for ES? And what are the future changes on the supply side (pressures and threats to the ecosystem)? Methodology: The City of Barisal in Bangladesh has a calculated number of around 10.000 urban rain-fed ponds,representing 6.5% of the city area, which represents a huge natural water supply and gives the city its characteristic face. In August 2015 a user survey was conducted in the city of Barisal, in every ward (administrative unit), to determine the demand for ecosystem services related to urban ponds, evaluating over 600 ponds. The findings will present the huge variation of provisioning ecosystem services and an important regulating service, related to economic and domestic use, in a spatial resolution. It will be shown, how the importance of ES changes, by changing the unit of analysis (families or ponds or the city) and the importance for the livelihood of pond owners and users. A relationship between pond area(m2) and number of users was detected, also the role of compensation payments for the pond owners by the users. It will be shown how natural capital, privately and publicly owned,contributes in an important way in buffering unequal distribution of societies resources in the short- and long-run. However society's demand for ES

  2. Water quality characteristics of rivers and ponds in Japan

    Institute of Scientific and Technical Information of China (English)

    幸彦; 杜茂安; 玄正

    2004-01-01

    In Japan, various countermeasures have been taken to improve the water quality of public waters such as rivers and lakes. Though water quality has improved, it is still insufficient. In summer, eutrophication is seen in lakcs and inner bays, as well as rivers. As a countermeasure to prevent eutrophication, the removal treatment of nutrient salts such as nitrogen and phosphorus is done, in addition to organic substance elimination in the domestic sewerage system. This report will show the water quality characteristics of rivers and ponds in Japan. It is considered that these investigative results are effective when the water quality improvement of the stabilization ponds where eutrophication occurs are examined in China.

  3. Network effects, cascades and CCP interoperability

    Science.gov (United States)

    Feng, Xiaobing; Hu, Haibo; Pritsker, Matthew

    2014-03-01

    To control counterparty risk, financial regulations such as the Dodd Frank Act are increasingly requiring standardized derivatives trades to be cleared by central counterparties (CCPs). It is anticipated that in the near-term future, CCPs across the world will be linked through interoperability agreements that facilitate risk-sharing but also serve as a conduit for transmitting shocks. This paper theoretically studies a network with CCPs that are linked through interoperability arrangements, and studies the properties of the network that contribute to cascading failures. The magnitude of the cascading is theoretically related to the strength of network linkages, the size of the network, the logistic mapping coefficient, a stochastic effect and CCP's defense lines. Simulations indicate that larger network effects increase systemic risk from cascading failures. The size of the network N raises the threshold value of shock sizes that are required to generate cascades. Hence, the larger the network, the more robust it will be.

  4. Cascade theory in isotopic separation processes

    International Nuclear Information System (INIS)

    Three main areas are developed within the scope of this work: - the first one is devoted to fundamentals: separative power, value function, ideal cascade and square cascade. Applications to two main cases are carried out, namely: Study of binary isotopic mix, Study of processes with a small enrichment coefficient. - The second one is devoted to cascade coupling -high-flux coupling (more widely used and better known) as well as low-flux coupling are presented and compared to one another. - The third one is an outlook on problems linked to cascade transients. Those problem are somewhat intricate and their interest lies mainly into two areas: economics where the start-up time may have a large influence on the interests paid during the construction and start-up period, military productions where the start-up time has a direct bearing on the production schedule. (author). 50 figs. 3 annexes. 12 refs. 6 tabs

  5. Cascade Error Projection: A New Learning Algorithm

    Science.gov (United States)

    Duong, T. A.; Stubberud, A. R.; Daud, T.; Thakoor, A. P.

    1995-01-01

    A new neural network architecture and a hardware implementable learning algorithm is proposed. The algorithm, called cascade error projection (CEP), handles lack of precision and circuit noise better than existing algorithms.

  6. Multilevel Inverter by Cascading Industrial VSI

    DEFF Research Database (Denmark)

    Teodorescu, Remus; Blaabjerg, Frede; Pedersen, John Kim; Cengelci, E.; Enjeti, P.

    2002-01-01

    the motor rated kVA. The concept of using cascaded inverters is further extended to a new modular motor-modular inverter system where the motor winding connections are reconnected into several three-phase groups, either six-lead or 12-lead connection according to the voltage level, each powered by a......In this paper the modularity concept applied to medium-voltage adjustable speed drives is addressed. First, the single-phase cascaded voltage-source inverter that uses series connection of IGBT H-bridge modules with isolated dc-buses is presented. Next, a novel three-phase cascaded voltage...... standard triphase IGBT inverter module. Thus, a high fault tolerance is being achieved and the output transformer requirement is eliminated. A staggered space-vector modulation technique applicable to three-phase cascaded voltage-source inverter topologies is also demonstrated. Both computer simulations...

  7. Model for cascading failures in congested Internet

    Institute of Scientific and Technical Information of China (English)

    Jian WANG; Yan-heng LIU; Jian-qi ZHU; Yu JIAO

    2008-01-01

    Cascading failures often occur in congested networks such as the Internet. A cascading failure can be described as a three-phase process: generation, diffusion, and dissipation of the congestion. In this account, we present a function that represents the extent of congestion on a given node. This approach is different from existing functions based on betweenness centrality. By introducing the concept of 'delay time', we designate an intergradation between permanent removal and nouremoval. We also construct an evaluation function of network efficiency, based on congestion, which measures the damage caused by cascading failures. Finally, we investigate the effects of network structure and size, delay time, processing ability and packet generation speed on congestion propagation. Also, we uncover the relationship between the cascade dynamics and some properties of the network such as structure and size.

  8. Compression limits in cascaded quadratic soliton compression

    DEFF Research Database (Denmark)

    Bache, Morten; Bang, Ole; Krolikowski, Wieslaw;

    2008-01-01

    Cascaded quadratic soliton compressors generate under optimal conditions few-cycle pulses. Using theory and numerical simulations in a nonlinear crystal suitable for high-energy pulse compression, we address the limits to the compression quality and efficiency.......Cascaded quadratic soliton compressors generate under optimal conditions few-cycle pulses. Using theory and numerical simulations in a nonlinear crystal suitable for high-energy pulse compression, we address the limits to the compression quality and efficiency....

  9. Nonlinear response of quantum cascade structures

    OpenAIRE

    Winge, David; Lindskog, Martin; Wacker, Andreas

    2012-01-01

    The gain spectrum of a terahertz quantum cascade laser is analyzed by a nonequilibrium Green's functions approach. Higher harmonics of the response function were retrievable, providing a way to approach nonlinear phenomena in quantum cascade lasers theoretically. Gain is simulated under operation conditions and results are presented both for linear response and strong laser fields. An iterative way of reconstructing the field strength inside the laser cavity at lasing conditions is descri...

  10. Quantum dot cascade laser: Arguments in favor

    OpenAIRE

    Dmitriev, I. A.; Suris, R. A.

    2007-01-01

    Quantum cascade lasers are recognized as propitious candidates for future terahertz optoelectronics. Here we demonstrate several definite advantages of quantum dot cascade structures over quantum well devices, which suffer fundamental performance limitations owing to continuous carrier spectrum. The discrete spectrum of quantum dots opens an opportunity to control the non-radiative relaxation and optical loss and also provides for more flexibility in the choice of an optical and electrical de...

  11. Emission spectra of terahertz quantum cascade laser

    OpenAIRE

    Antonov, A V; Gavrilenko, V. I.; Ikonnikov, A. V.; Maremyanin, K. V.; Lastovkin, A. A.; Morozov, S. V.; Ushakov, D.V.; Sadofyev, Yu. G.; N. Samal

    2009-01-01

    We calculated energy levels, wave functions, and energies of radiative transitions in terahertz quantum cascade lasers based on GaAs/Al0.15Ga0.85As heterostructures. Current-voltage characteristics and current dependences of laser radiation intensity were measured, and the maximum operating temperatures reaching 85 K were determined. Radiation spectra of quantum cascade lasers were measured for different temperatures, and the effect of intensity “pumping” from lowfrequency mode...

  12. Designing the Cascade inertial confinement fusion reactor

    International Nuclear Information System (INIS)

    The primary goal in designing inertial confinement fusion (ICF) reactors is to produce electrical power as inexpensively as possible, with minimum activation and without compromising safety. This paper discusses a method for designing the Cascade rotating ceramic-granule-blanket reactor (Pitts, 1985) and its associated power plant (Pitts and Maya, 1985). Although focus is on the cascade reactor, the design method and issues presented are applicable to most other ICF reactors

  13. Small Thaw Ponds: An Unaccounted Source of Methane in the Canadian High Arctic

    OpenAIRE

    Karita Negandhi; Isabelle Laurion; Whiticar, Michael J; Pierre E Galand; Xiaomei Xu; Connie Lovejoy

    2013-01-01

    Thawing permafrost in the Canadian Arctic tundra leads to peat erosion and slumping in narrow and shallow runnel ponds that surround more commonly studied polygonal ponds. Here we compared the methane production between runnel and polygonal ponds using stable isotope ratios, ¹⁴C signatures, and investigated potential methanogenic communities through high-throughput sequencing archaeal 16S rRNA genes. We found that runnel ponds had significantly higher methane and carbon dioxide emissions, pro...

  14. Two-Dimensional Numerical Modeling of a Salt Gradient Solar Pond

    Science.gov (United States)

    Amini, Javad; Dehghan, Ali A.

    2008-09-01

    A two-dimensional numerical model is developed in order to simulate the transient thermal behavior of a salt gradient solar pond. Transient dimensionless governing equations in the form of mass, momentum, energy and concentration are discretized by employing the finite volume method and solved by using SIMPLE algorithm. Ponds with different aspect ratios are considered. The pond walls shadows and radiation attenuation in water are among the parameters whose influences on the pond thermal and flow fields are determined and discussed.

  15. Evaluation of the Preservation Value and Location of Farm Ponds in Yunlin County, Taiwan

    OpenAIRE

    Wen-Wen Chou; Soen-Han Lee; Chen-Fa Wu

    2013-01-01

    Farm ponds in Yunlin County first appeared in 1,622 and have played roles in habitation, production, the ecology, culture, and disaster reduction. Farm ponds largely disappeared with the development of urban areas and the industrial sector; thus, effective preservation of the remaining ponds is critical. The criteria to evaluate the preservation value of farm ponds is established by expert questionnaires which follow the Fuzzy Delphi Method (FDM) and Fuzzy Analytic Hierarchy Process (FAHP), a...

  16. The mitigation of power plant ash and slag pond's impact upon the environment

    International Nuclear Information System (INIS)

    The ash and slag ponds have a notable impact upon the environment that starts from the settlement of the yard for the future pond and lasts after the storing capacity runs out. In the case of the active ash ponds the main environmental impacts are due to ash sweeping off by wind and pollution of underground water by the infiltration of the leachate in soil. The main solutions of mitigate the impact of active and abandoned ash ponds are presented. (author) 9 refs

  17. Biological diversity of copepods and cladocerans in Mediterranean temporary ponds under periods of contrasting rainfall

    Directory of Open Access Journals (Sweden)

    Maria-José BOAVIDA

    2010-02-01

    Full Text Available The zooplankton communities of 5 temporary ponds in the Northern part of the Natural Park of the Southwest and Vicentina Coast (PNCSV, Southwestern Portugal, were studied during two consecutive years of contrasting rainfall. A total of ten cladoceran species and eleven copepod species (3 diaptomids, 5 cyclopoids and 3 harpacticoids were recorded. The community structure varied along the hydrological period of the ponds. Some species were restricted to the early period of the pond (Diaptomus kenitraensis, Hemidiaptomus roubaui, Daphnia hispanica while others started to build large populations in the middle of the hydroperiod and dominated the communities at the later stages of the hydroperiod: Dussartius baeticus and Ceriodaphnia reticulata dominated the larger ponds, while C. reticulata and Simocephalus exspinosus dominated the smaller ponds. Alpha and beta diversity of cladoceran and copepod species were calculated for the ponds of different hydroperiod length (i.e., water residence time and area. Alpha diversity was defined as the total diversity of species associated with each pond throughout the annual hydrological period. Copepod and cladoceran communities associated with larger ponds were more diverse than the communities of smaller ponds. As several pond species occur in succession during the length of hydrological period, a longer hydroperiod (2006/2007 allowed for the establishment of a larger number of species than a shorter hydroperiod (2007/2008. Beta diversity was considered as the turnover of species in the gradient of pond area and was higher in the longer hydrological period than in the shorter hydrological period. The degree of diversity change between pairs of ponds was larger between any of the two smaller ponds and any of the larger ponds. This is the first study on the richness of planktonic micro-crustaceans in Portuguese temporary ponds. It is our purpose to increase the knowledge on these taxa to highlight the importance

  18. Impact of Population and Latrines on Fecal Contamination of Ponds in Rural Bangladesh

    OpenAIRE

    Knappett, Peter S. K.; Escamilla, Veronica; Layton, Alice; McKay, Larry D.; Emch, Michael; Williams, Daniel E.; Huq, Md. R.; Alam, Md. J.; Farhana, Labony; Mailloux, Brian J.; Ferguson, Andy; Sayler, Gary S.; Ahmed, Kazi M.; van Geen, Alexander

    2011-01-01

    A majority of households in Bangladesh rely on pond water for hygiene. Exposure to pond water fecal contamination could therefore still contribute to diarrheal disease despite the installation of numerous tubewells for drinking. The objectives of this study are to determine the predominant sources (human or livestock) of fecal pollution in ponds and examine the association between local population, latrine density, latrine quality and concentrations of fecal bacteria and pathogens in pond wat...

  19. Emergence of event cascades in inhomogeneous networks.

    Science.gov (United States)

    Onaga, Tomokatsu; Shinomoto, Shigeru

    2016-01-01

    There is a commonality among contagious diseases, tweets, and neuronal firings that past events facilitate the future occurrence of events. The spread of events has been extensively studied such that the systems exhibit catastrophic chain reactions if the interaction represented by the ratio of reproduction exceeds unity; however, their subthreshold states are not fully understood. Here, we report that these systems are possessed by nonstationary cascades of event-occurrences already in the subthreshold regime. Event cascades can be harmful in some contexts, when the peak-demand causes vaccine shortages, heavy traffic on communication lines, but may be beneficial in other contexts, such that spontaneous activity in neural networks may be used to generate motion or store memory. Thus it is important to comprehend the mechanism by which such cascades appear, and consider controlling a system to tame or facilitate fluctuations in the event-occurrences. The critical interaction for the emergence of cascades depends greatly on the network structure in which individuals are connected. We demonstrate that we can predict whether cascades may emerge, given information about the interactions between individuals. Furthermore, we develop a method of reallocating connections among individuals so that event cascades may be either impeded or impelled in a network. PMID:27625183

  20. Oxygen transfer in marsh-pond-marsh constructed wetlands treating swine wastewater

    Science.gov (United States)

    Marsh-pond-marsh (M-P-M) constructed wetlands have been used to treat wastewater from swine anaerobic lagoons. To mitigate undesired ammonia emission from M-P-M, ponds were covered with floating wetlands (M-FB-M). The pond sections of the M-FB-M were covered with floating wetlands consisted of recyc...

  1. 78 FR 23949 - Sunkhaze Meadows National Wildlife Refuge and Carlton Pond Waterfowl Production Area, Penobscot...

    Science.gov (United States)

    2013-04-23

    ... and Carlton Pond WPA. We started this process through a notice in the Federal Register (76 FR 14984... Fish and Wildlife Service Sunkhaze Meadows National Wildlife Refuge and Carlton Pond Waterfowl... Meadows National Wildlife Refuge (NWR) and Carlton Pond Waterfowl Production Area (WPA), located...

  2. 33 CFR 208.27 - Fort Cobb Dam and Reservoir, Pond (Cobb) Creek, Oklahoma.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 3 2010-07-01 2010-07-01 false Fort Cobb Dam and Reservoir, Pond..., Pond (Cobb) Creek, Oklahoma. The Bureau of Reclamation shall operate the Fort Cobb Dam and Reservoir in... inflow below the dam, will not produce flows in excess of bankfull on Pond (Cobb) Creek downstream of...

  3. Pumping performance of a slow-rotating paddlewheel for split-ponds

    Science.gov (United States)

    Commercial catfish farmers are intensifying production by retrofitting ponds with variations of the partitioned aquaculture system. The split-pond system is the most common variation used commercially. The split-pond consists of a small fish-holding basin connected to a waste treatment lagoon by two...

  4. Performance and Modelling of a Highway Wet Detention Pond Designed for Cold Climate

    DEFF Research Database (Denmark)

    Vollertsen, Jes; Åstebøl, Svein Ole; Coward, Jan Emil;

    2009-01-01

    A wet detention pond in Norway has been monitored for 12 months. The pond receives runoff from a highway with a traffic load of 42,000 average daily traffic. Hydraulic conditions in terms of inflow, outflow, and pond water level were recorded every minute. Water quality was monitored by volume pr...

  5. Evaluation of the preservation value and location of farm ponds in Yunlin County, Taiwan.

    Science.gov (United States)

    Chou, Wen-Wen; Lee, Soen-Han; Wu, Chen-Fa

    2014-01-01

    Farm ponds in Yunlin County first appeared in 1,622 and have played roles in habitation, production, the ecology, culture, and disaster reduction. Farm ponds largely disappeared with the development of urban areas and the industrial sector; thus, effective preservation of the remaining ponds is critical. The criteria to evaluate the preservation value of farm ponds is established by expert questionnaires which follow the Fuzzy Delphi Method (FDM) and Fuzzy Analytic Hierarchy Process (FAHP), and GIS, which are integrated into a spatial analysis of the remaining 481 farm ponds in Yunlin County. The results show that 28 ponds should be preserved to continue the cultural interaction between farm ponds and settlements; 36 ponds should preserved to connect coasts and streams, which are important habitats for birds; 30 ponds should be preserved to increase storage capacity, recharge groundwater, and reduce land subsidence; four ponds should be preserved as Feng-Shui ponds in front of temples in settlements or as recreation areas for local citizens; and four farms should be preserved (high priority) in agricultural production areas to support irrigation. In short, FAHP and GIS are integrated to evaluate the number and locations of farm ponds that provide water for habitation, production, the ecology, culture, and disaster reduction and maintain the overall preservation value in Yunlin County. The results could inform governmental departments when considering conservation policies. PMID:24384776

  6. Evaluation of the Preservation Value and Location of Farm Ponds in Yunlin County, Taiwan

    Directory of Open Access Journals (Sweden)

    Wen-Wen Chou

    2013-12-01

    Full Text Available Farm ponds in Yunlin County first appeared in 1,622 and have played roles in habitation, production, the ecology, culture, and disaster reduction. Farm ponds largely disappeared with the development of urban areas and the industrial sector; thus, effective preservation of the remaining ponds is critical. The criteria to evaluate the preservation value of farm ponds is established by expert questionnaires which follow the Fuzzy Delphi Method (FDM and Fuzzy Analytic Hierarchy Process (FAHP, and GIS, which are integrated into a spatial analysis of the remaining 481 farm ponds in Yunlin County. The results show that 28 ponds should be preserved to continue the cultural interaction between farm ponds and settlements; 36 ponds should preserved to connect coasts and streams, which are important habitats for birds; 30 ponds should be preserved to increase storage capacity, recharge groundwater, and reduce land subsidence; four ponds should be preserved as Feng-Shui ponds in front of temples in settlements or as recreation areas for local citizens; and four farms should be preserved (high priority in agricultural production areas to support irrigation. In short, FAHP and GIS are integrated to evaluate the number and locations of farm ponds that provide water for habitation, production, the ecology, culture, and disaster reduction and maintain the overall preservation value in Yunlin County. The results could inform governmental departments when considering conservation policies.

  7. Phytoplankton succession in sunshine bass fry ponds and the effect of Aquashade®

    Science.gov (United States)

    Phytoplankton management in aquaculture ponds is very critical in maintaining good quality water for culturing fish especially during the fry and fingerling stages. Though much is known about succession in catfish ponds, that is not the case for sunshine bass ponds. This study was designed to look a...

  8. Review and evaluation of information on the thermal performance of ultimate heat sinks: spray ponds and cooling ponds

    International Nuclear Information System (INIS)

    A report is presented which identifies and evaluates available information and data useful in validating and improving existing models for the thermal performance of ultimate heat sinks. Included are discussions of the thermal elements of cooling ponds and spray ponds, the available information and data pertinent to the problem, and the requirements and needs for further research and performance data. An outline is presented of the necessary elements required for a performance test of an ultimate heat sink before the system is thermally approved. (auth)

  9. Par Pond vegetation status summer 1995 - July survey descriptive summary

    International Nuclear Information System (INIS)

    A survey of the emergent shoreline aquatic plant, communities began in June 1995, three months after the refilling of Par Pond to approximately 200 feet (61 meters) above mean sea level, and continued with this July survey. Aquatic plant communities, similar to the pre-drawdown Par Pond communities, are becoming reestablished. Beds of maidencane (Panicum hemitomon), lotus (Nelumbo lutea), water lily (Nymphaea odorata), and watershield (Brasenia schreberi) are now extensive and well established. In addition, within isolated coves, extensive beds of water lilies and spike-rush (Eleocharis sp.) are common. Cattail occurrence has increased since refill, but large beds common to Par Pond prior to the drawdown have not formed. Invasion of willow (Salix sp.) and red maple (Acer rubrum) occurred along the lake shoreline during drawdown. The red maples along the present shoreline are beginning to show evidence of stress and mortality from flooding over the past four months. Some of the willows appear to be stressed as well. The loblolly pines (Pinus taeda), which were flooded in all but the shallow shoreline areas, are now dead. Future surveys are planned for the growing seasons of 1995, 1996, and 1997, along with the evaluation of satellite data for mapping the areal extent of the macrophyte beds of Par Pond

  10. Efficiency of aquatic macrophytes to treat Nile tilapia pond effluents

    Directory of Open Access Journals (Sweden)

    Henry-Silva Gustavo Gonzaga

    2006-01-01

    Full Text Available The effluents from fish farming can increase the quantity of suspended solids and promote the enrichment of nitrogen and phosphorus in aquatic ecosystems. In this context, the aim of this work was to evaluate the efficiency of three species of floating aquatic macrophytes (Eichhornia crassipes, Pistia stratiotes and Salvinia molesta to treat effluents from Nile tilapia culture ponds. The effluent originated from a 1,000-m² pond stocked with 2,000 male Nile tilapia Oreochromis niloticus. The treatment systems consisted of 12 experimental tanks, three tanks for each macrophyte species, and three control tanks (without plants. Water samples were collected from the: (i fish pond source water, (ii effluent from fish pond and (iii effluents from the treatment tanks. The following water variables were evaluated: turbidity, total and dissolved nitrogen, ammoniacal-N, nitrate-N, nitrite-N, total phosphorus and dissolved phosphorus. E. crassipes and P. stratiotes were more efficient in total phosphorus removal (82.0% and 83.3%, respectively and total nitrogen removal (46.1% and 43.9%, respectively than the S. molesta (72.1% total phosphorus and 42.7% total nitrogen and the control (50.3% total phosphorus and 22.8% total nitrogen, indicating that the treated effluents may be reused in the aquaculture activity.

  11. Water quality in hybrid catfish ponds after partial fish harvest

    Science.gov (United States)

    Intensification of United States catfish aquaculture involves hybrid catfish ('channel catfish Ictalurus punctatus x ' blue catfish I. furcatus) grown in ponds with abundant aeration and high feeding rates. High feeding rates cause water quality deterioration because most of the nitrogen, phosphorus...

  12. Bioclogging and Biocementation in Construction of Water Pond in Sand

    Science.gov (United States)

    Chu, J.; Ivanov, V.; Stabnikov, V.; Li, B.

    2012-12-01

    Conventionally, compacted bentonite, geosynthetic clay liner or plastic liners are used to seal ponds, channels, and reservoirs in sand. Recently, a new approach to form a low permeability layer of several centimetres thick through the microbially induced calcium carbonate precipitation (MICP) process has been developed (Chu et al., 2012). This method has been adopted to build a laboratory scale water pond model in sand. Calcium solution for bioclogging and biocementation was supplied initially by spaying to form a layer of the clogged sand by precipitation in the pores and then by slow percolation from solution above sand surface, which formed a crust of calcite. This combination of bioclogging and biocementation formed a sand layer of 1 - 3 cm depth with low permeability. The permeability of sand after this treatment was reduced from the order of 10^-4 m/s to 10^-7 m/s when an average 2.1 kg of Ca per m^2 of sand surface was precipitated. The bending strengths of the walls and the base of the model pond were in the range of 90 to 256 kPa. The unconfined compressive strengths obtained from samples from the walls and the base were in the range of 215 to 932 kPa. The graded sand and uniform supply of calcium solution were used for the model pond construction but it was significant spatial three-dimensional heterogeneity of sand bioclogging and biocementation.

  13. Radiological impact of Par Pond drawdown from liquid effluent pathways

    International Nuclear Information System (INIS)

    The water level of Par Pond has been lowered over the past several months to reduce the effects in the event of catastrophic dam failure while assessing the condition of the dam and determining if repairs are necessary. In lowering the level of Par Pond, 60 billion liters of water containing low levels of tritium and cesium-137 were discharged to several onsite streams. SRS surface streams flow to the Savannah River. An assessment made to determine the total amount of tritium and Cs-137 discharged and to estimate the consequences to downstream Savannah River users. It is estimated that a total of 160 curies of tritium were displaced from Par Pond to the Savannah River between June 28, 1991 and September 19, 1991. This release could hypothetically result in a maximum individual dose of 3. 2x10-4 mrem and a total (80-km and drinking water populations) population dose of 1.4x10-2 person-rem. Likewise, a maximum individual dose of 5.0x10-2 mrem and a total population dose of 1.7x10-1 person- rem are predicted as a result of an estimated 0.21 curies of Cs-137 being discharged from Par Pond to the Savannah River

  14. Coleman Revisited: School Segregation, Peers, and Frog Ponds

    Science.gov (United States)

    Goldsmith, Pat Rubio

    2011-01-01

    Students from minority segregated schools tend to achieve and attain less than similar students from White segregated schools. This study examines whether peer effects can explain this relationship using normative models and frog-pond models. Normative models (where peers become alike) suggest that minority schoolmates are a liability. Frog-pond…

  15. Pathogen removal mechanisms in macrophyte and algal waste stabilization ponds

    NARCIS (Netherlands)

    Awuah, E.

    2006-01-01

    Waste stabilization ponds are recognized as the solution to domestic wastewater treatment in developing countries. The use of such natural systems is considered to be very important. This is because it is cheap, easy to construct and they do not require high skilled labour. In the developing countri

  16. Bilingual Creativity in Chinese English: Ha Jin's "In the Pond."

    Science.gov (United States)

    Zhang, Hang

    2002-01-01

    Addresses issues related to bilingual creativity in Chinese English and their implications for world Englishes in the Chinese context. The language examined is drawn from Ha Jin's novella, "In the Pond, in which the author's use of English is nativized in the Chinese context in order to recast the cultural meanings of the language. (Author/VWL)

  17. How Circulation of Water Affects Freezing in Ponds

    Science.gov (United States)

    Moreau, Theresa; Lamontagne, Robert; Letzring, Daniel

    2007-01-01

    One means of preventing the top of a pond from freezing involves running a circulating pump near the bottom to agitate the surface and expose it to air throughout the winter months. This phenomenon is similar to that of the flowing of streams in subzero temperatures and to the running of taps to prevent pipe bursts in winter. All of these cases…

  18. Science from the Pond up: Using Measurement to Introduce Inquiry

    Science.gov (United States)

    Demir, Abdulkadir; Schmidt, Frank; Abell, Sandra K.

    2010-01-01

    The authors engaged nonscience majors enrolled in an integrated science course with a prototype activity designed to change their mindset from cookbook to inquiry science. This article describes the activity, the Warm Little Pond, which helped students develop essential understanding of basic statistics, significant figures, and the idea that…

  19. Removal of Heavy Metals and PAH in Highway Detention Ponds

    DEFF Research Database (Denmark)

    Bentzen, Thomas Ruby; Larsen, Torben; Thorndahl, Søren Liedtke;

    2005-01-01

    rainfalls. The modelling will take place in a special version of the MIKE URBAN. The modelling is calibrated and validated on measurements from selected highway catchments. The removal of pollutants in the ponds is studied by local measurements in combination with CFD modelling using the MIKE 21 and MIKE 3...

  20. Nitrogen transformations and fluxes in fish ponds: a modelling approach

    NARCIS (Netherlands)

    Jimenez-Montealegre, R.A.

    2001-01-01

    Nitrogen is a key element in aquatic environments, and in Aquaculture it is an important pond management variable. In current aquaculture research two important goals are to maintain the water quality within the system, and to improve the retention of nutrients applied to the system in order to mini

  1. Physico-chemical factors and bacteria in fish ponds

    OpenAIRE

    Jun, X.; Xiuzheng, F.; Tongbing, Y.

    2000-01-01

    Analyses of pond water and mud samples show that nitrifying bacteria (including ammonifying bacteria, nitrite bacteria, nitrobacteria and denitrifying bacteria) are in general closely correlated with various physico-chemical factors, ammonifying bacteria are mainly correlated with dissolved oxygen; denitrifying bacteria are inversely correlated with phosphorus; nitrite bacteria are closely correlated with nitrites, nitrobacteria are inversely correlated with ammoniac nitrogen. The nitrifying ...

  2. Inventory of vegetation and benthos in newly laid and natural ponds in Forsmark 2012

    International Nuclear Information System (INIS)

    SKB plans to build a repository for the spent nuclear fuel. The repository is planned to be built in Forsmark and constitutes installations above and below ground. The building and operation of the construction will involve activities that might affect the nature in the area. The impact means, among other things, that a small water body, which today is a reproduction site for the red listed pool frog (Rana lessonae), will disappear. The lost locality for the pool frog has been compensated by creating four new ponds in the Forsmark area. This study is part of the follow-up of these new habitats. The aim is to describe the plant and animal communities in the ponds, and follow the succession, i.e. the development of the habitats. The study also includes two natural ponds that will serve as reference objects. The survey of vegetation and invertebrate fauna in the ponds was conducted in October 2012. The results show that the new ponds had low coverage of submersed vegetation and the species composition in the plant communities differed between the ponds. The reference ponds also had different plant communities, both in terms of species composition and coverage. This indicates that the species composition of the plant communities in the new ponds will likely depend on physical factors specific to the respective pond, but that higher vegetation coverage can be expected over time in all new ponds. The reference ponds had similar animal communities that differed from the animal communities in the new ponds. The similar species composition in the reference ponds, despite the variety of plant communities, suggests that similar animal communities are likely to develop in the new ponds, even if the plant communities continues to be different. Water chemical sampling has also been conducted in the ponds during 2012. A comparison of the inorganic environment (with regard to analysed ions) showed that the reference ponds had relatively similar ion compositions with little

  3. Distribution and Diversity of Oligochaetes in Selected Ponds of Thiruvananthapuram District, Kerala, South India

    Directory of Open Access Journals (Sweden)

    M. S. Ragi

    2014-01-01

    Full Text Available The present study was carried out to evaluate the distribution and diversity of oligochaete fauna in selected ponds of Thiruvananthapuram district in Kerala, South India. The sediment samples were collected from three ponds seasonally during the period December 2006 to November 2008. In the study, 10 oligochaete species which belong to 8 genera were identified in three selected ponds. These include Dero digitata, Dero nivea, Dero obtusa, Pristina longiseta, Aulophorus furcatus, Stylaria fossularis, Chaetogaster spp., Aeolosoma spp., Tubifex tubifex and Limnodrilus hoffmeisteri. Tubifex tubifex and Limnodrilus hoffmeisteri are the pollution-indicator oligochaete species identified in the fresh water ponds, which reveals that the studied ponds are subjected to pollution.

  4. A note on the shallow ponds on the gravel ridge of Epping Forest, Essex

    OpenAIRE

    Wheeler, Alwyne

    1998-01-01

    In a recent study in Freshwater Forum on Speakman's Pond (also known as Nursery Pond) the impression was given that it had been a permanent water-filled pond which had recently dried out due to exceptionally low rainfall. In fact, Nursery Pond was created by the extraction of gravel and was never more than 50 cm deep, until the creation of trenches in 1989 to provide a refuge for aquatic life. The Nursery Pond followed a seasonal pattern of filling with winter rain and slowly drying out betwe...

  5. Creation of temporary ponds for amphibians in northern and central Europe

    OpenAIRE

    Briggs, Lars

    2001-01-01

    More than 4000 ponds have been created or restored in Denmark since 1985 as part of a large-scale pond-digging programme to protect endangered amphibians in particular and pond flora and fauna in general. Most ponds are created on private land with public financing. The programme was triggered by, among other factors, a drastic decline in amphibian populations in Denmark between 1940 and 1980. However, in recent years there has been an increased awareness in Denmark that temporary ponds are i...

  6. A Mathematical Model for the Removal of Organic Mater in Stabilization Ponds

    Directory of Open Access Journals (Sweden)

    Medri Waldir

    2002-01-01

    Full Text Available This work presents an application to systemize the construction of ponds systems for treatment of domestic sewage. It consisted of two anaerobic ponds operated in parallel during May/97 to April/99. These were connected in series with a chicaned facultative pond. The treatment system was controlled with samples collected from the crude sewage (compound sample, in the affluents and effluents of the ponds and along the flux of the anaerobic and facultative ponds. The following parameters were analyzed: pH, Biochemical Oxygen Demand, Chemical Oxygen Demand, Total Solids, Sedimentable Solids, Total Coliforms, Oxygen Consumed in Acid Medium (OCAM and temperature.

  7. Bioaccumulation of heavy metals in fauna from wet detention ponds for stormwater runoff

    DEFF Research Database (Denmark)

    Stephansen, Diana; Nielsen, Asbjørn Haaning; Hvitved-Jacobsen, Thorkild;

    2012-01-01

    Stormwater detention ponds remove pollutants e.g. heavy metals and nutrients from stormwater runoff. These pollutants accumulate in the pond sediment and thereby become available for bioaccumulation in fauna living in the ponds. In this study the bioaccumulation was investigated by fauna samples...... from 5 wet detention ponds for analyses of heavy metal contents. Five rural shallow lakes were included in the study to survey the natural occurrence of heavy metals in water-dwelling fauna. Heavy metal concentrations in water-dwelling fauna were generally found higher in wet detention ponds compared...

  8. Harmonic cascade FEL designs for LUX

    Energy Technology Data Exchange (ETDEWEB)

    Penn, G.; Reinsch, M.; Wurtele, J.; Corlett, J.N.; Fawley, W.M.; Zholents, A.; Wan, W.

    2004-07-16

    LUX is a design concept for an ultrafast X-ray science facility, based on an electron beam accelerated to GeV energies in are circulating linac. Included in the design are short duration (200 fs or shorter FWHM) light sources using multiple stages of higher harmonic generation, seeded by a 200-250 nm laser of similar duration. This laser modulates the energy of a group of electrons within the electron bunch; this section of the electron bunch then produces radiation at a higher harmonic after entering a second, differently tuned undulator. Repeated stages in a cascade yield increasing photon energies up to 1 keV. Most of the undulators in the cascade operate in the low-gain FEL regime. Harmonic cascades have been designed for each pass of the recirculating linac up to a final electron beam energy of 3.1 GeV. For a given cascade, the photon energy can be selected over a wide range by varying the seed laser frequency and the field strength in the undulators. We present simulation results using the codes GENESIS and GINGER, as well as the results of analytical models which predict FEL performance. We discuss lattice considerations pertinent for harmonic cascade FELs, as well as sensitivity studies and requirements on the electron beam.

  9. CASCAD dry storage concept for spent fuel

    International Nuclear Information System (INIS)

    Further to a cost-benefit analysis of the various medium-term and long-term and H.L.W. storage possibilities, C.E.A. (French Atomic Energy Commission) and S.G.N. decided to develop an original dry storage process with natural convection cooling that offers many advantages: cut in the total investment and operating costs; high operating safety; natural convection cooling; existence of two containment barriers irrespective of the assumed clad conditions; flexible, modular and compact design. The process was first implemented in the so-called CASCAD Cadarache Facility (vault-type facility) constructed in Cadarache mainly to store fuel from Brennilis heavy water reactor. For the purpose, a large program was set up to develop and validate computer codes, in particular with the use of mockups. On the request of many clients, and owing to the outstanding operating results of the CASCAD Cadarache Facility, SGN was brought to adapt the process to the storage of other types of fuel: LWR, PWR, BWR, MOX/High burn up; WWER 440 and WWER 1000; RBMK. Our paper highlights the main features of: the CASCAD design; the operating experience from the CASCAD Cadarache Facility; the adaptation of the CASCAD process to the above-listed types of fuel. (author)

  10. SRF Based Cascaded Multilevel Active Filter

    Directory of Open Access Journals (Sweden)

    Narisetti Sai Lakshmi#1, B.N. Kartheek

    2013-04-01

    Full Text Available In this paper a power line conditioner using a cascaded multilevel inverter based shunt active filter using synchronous reference frame (SRF controller is developed to improve the power quality in the distribution system . The cascaded multilevel inverter consists of two H-bridges in which each bridge has separate dc source. Gating signals to the cascaded multilevel voltage source inverter are generated from proposed triangular-carrier current controller. Here control strategy is different from conventional methods and provides superior performance. Using Reference Frame Transformation, the current is transformed from a − b − c stationery frame to rotating 0 − d − q frame. Using the PI controller, the current in the 0 − d − q frame is controlled to get the desired reference signal. This proposed cascaded five level active power filter system is validated through MATLAB/SIMULINK Platform. From simulation results observed that the cascaded multilevel inverter based shunt active filter effectively compensates the current harmonics.

  11. Parametric study of a shallow solar-pond under the batch mode of heat extraction

    Energy Technology Data Exchange (ETDEWEB)

    Aboul-Enein, S.; El-Sebaii, A.A.; Ramadan, M.R.I.; Khallaf, A.M. [Tanta University (Egypt). Dept. of Physics

    2004-06-01

    In this paper, the thermal performance of a shallow solar-pond (SSP) under the batch mode of heat extraction has been investigated theoretically and experimentally. A transient mathematical model has been proposed. A computer program has been developed based on an analytical solution of the energy-balance equations of different elements of the pond. Numerical calculations have been carried out to study the effects of various configurational and operational parameters on the pond's performance. To improve the pond's performance, an outer mirror is hinged outside the pond to increase the amount of solar radiation incident on the pond cover. Optimization of various dimensions of the pond has been carried out. Effects of the pond's water-depth X{sub w}, wind speed V, the sides' X{sub s} and back X{sub b} insulation thicknesses as well as the height C and width W of the outer mirror have been investigated. The influence of the number of glass covers over the pond during the night have also been studied. Comparisons between experimental and theoretical results showed that good agreement has been achieved. Experiments indicated that the pond could provide 88 1 of hot water at a maximum temperature of 60{sup o}C at sunset. The pond can retain hot water till 7.00 a.m. next day at a temperature of 47{sup o}C: this is suitable for domestic applications. (author)

  12. Fine-scale urbanization affects Odonata species diversity in ponds of a megacity (Paris, France)

    Science.gov (United States)

    Jeanmougin, Martin; Leprieur, Fabien; Loïs, Grégoire; Clergeau, Philippe

    2014-08-01

    Current developments in urban ecology include very few studies focused on pond ecosystems, though ponds are recognized as biodiversity hotspots. Using Odonata as an indicator model, we explored changes in species composition in ponds localized along an urban gradient of a megacity (Paris, France). We then assessed the relative importance of local- and landscape-scale variables in shaping Odonata α-diversity patterns using a model-averaging approach. Analyses were performed for adult (A) and adult plus exuviae (AE) census data. At 26 ponds, we recorded 657 adults and 815 exuviae belonging to 17 Odonata species. The results showed that the Odonata species assemblage composition was not determined by pond localization along the urban gradient. Similarly, pond characteristics were found to be similar among urban, suburban and periurban ponds. The analyses of AE census data revealed that fine-scale urbanization (i.e., increased density of buildings surrounding ponds) negatively affects Odonata α-diversity. In contrast, pond localization along the urban gradient weakly explained the α-diversity patterns. Several local-scale variables, such as the coverage of submerged macrophytes, were found to be significant drivers of Odonata α-diversity. Together, these results show that the degree of urbanization around ponds must be considered instead of pond localization along the urban gradient when assessing the potential impacts of urbanization on Odonata species diversity. This work also indicates the importance of exuviae sampling in understanding the response of Odonata to urbanization.

  13. Surface and subsurface soils at the Pond B dam: July 1998

    Energy Technology Data Exchange (ETDEWEB)

    Halverson, N.V.

    1999-12-03

    Pond B, 685-13G, is an inactive reactor cooling impoundment built in 1961 on the Savannah River Site (SRS). Between 1961 and 1964, Pond B received R-Reactor cooling water discharges that were contaminated with {sup 137}Cs, {sup 90}Sr and plutonium. Though the pond has not been used since 1964, radionuclides from the contaminated cooling water remain in the water and in the surface sediments of the pond. The current proposal to fix and repair the Pond B dam structure includes installing a new drain system and monitoring equipment. The dam will be reinforced with additional previous material on the downstream face of the dam. The objectives of this report are to describe the sampling methodology used during the July 1998 sampling event at the downstream face of the Pond B dam and in Pond B, present the results of the sampling event, and compare, where possible, these results to related risk-based standards.

  14. Studies of community structure and seasonal dynamics of planktonic copepods in saline-alkaline ponds

    Institute of Scientific and Technical Information of China (English)

    ZHAO Wen; DONG Shuanglin

    2005-01-01

    Species abundance and seasonal succession of copepods in aline-alkaline ponds were studied in Zhaodian Fish Farm, Gaoqing County, Shandong Province, from 5 April 1997 to 1 September 1998. The results indicated that in the conditions of salinity ranging from 1.36 to 20 g/L, total alkalinity changing from 2.4 to 7.2 mmol/L and pH 8-9, zooplankton in saline-alkaline ponds was composed of freshwater salt-tolerated species or halophile species, some of which are halobiont species and usually occurs in freshwater In our study, copepods were predominant in many fish-culture ponds and all control ponds without fishes in spring, late autumn and early winter Dominant species of copepods were Sinocalanus tenellus, Cyclops vicinus, Thermocyclops taihokuensis. The biomass of copepods in the control ponds without fishes was higher than that of the fish-culture ponds. ponds.

  15. Groundwater monitoring plan for the Hanford Site 216-B-3 pond RCRA facility

    International Nuclear Information System (INIS)

    The 216-B-3 pond system was a series of ponds for disposal of liquid effluent from past Hanford production facilities. In operation since 1945, the B Pond system has been a RCRA facility since 1986, with Resource Conservation and Recovery Act (RCRA) interim-status groundwater monitoring in place since 1988. In 1994, discharges were diverted from the main pond, where the greatest potential for contamination was thought to reside, to the 3C expansion pond. In 1997, all discharges to the pond system were discontinued. In 1990, the B Pond system was elevated from detection groundwater monitoring to an assessment-level status because total organic halogens and total organic carbon were found to exceed critical means in two wells. Subsequent groundwater quality assessment failed to find any specific hazardous waste contaminant that could have accounted for the exceedances, which were largely isolated in occurrence. Thus, it was recommended that the facility be returned to detection-level monitoring

  16. Groundwater monitoring plan for the Hanford Site 216-B-3 pond RCRA facility

    Energy Technology Data Exchange (ETDEWEB)

    Barnett, D.B.; Chou, C.J.

    1998-06-01

    The 216-B-3 pond system was a series of ponds for disposal of liquid effluent from past Hanford production facilities. In operation since 1945, the B Pond system has been a RCRA facility since 1986, with Resource Conservation and Recovery Act (RCRA) interim-status groundwater monitoring in place since 1988. In 1994, discharges were diverted from the main pond, where the greatest potential for contamination was thought to reside, to the 3C expansion pond. In 1997, all discharges to the pond system were discontinued. In 1990, the B Pond system was elevated from detection groundwater monitoring to an assessment-level status because total organic halogens and total organic carbon were found to exceed critical means in two wells. Subsequent groundwater quality assessment failed to find any specific hazardous waste contaminant that could have accounted for the exceedances, which were largely isolated in occurrence. Thus, it was recommended that the facility be returned to detection-level monitoring.

  17. Farmed areas predict the distribution of amphibian ponds in a traditional rural landscape.

    Directory of Open Access Journals (Sweden)

    Tibor Hartel

    Full Text Available BACKGROUND: Traditional rural landscapes of Eastern Europe are undergoing major changes due to agricultural intensification, land abandonment, change in agricultural practices and infrastructural development. Small man-made ponds are important yet vulnerable components of rural landscapes. Despite their important role for biodiversity, these ponds tend to be excluded from conservation strategies. METHODOLOGY/FINDINGS: Our study was conducted in a traditional rural landscape in Eastern Europe. The aim of this study is twofold: (i to model the distribution of four major man-made pond types and (ii to present the importance of man-made ponds for the endangered Yellow Bellied Toad (Bombina variegata and the Common Toad (Bufo bufo. Six environmental variables were used to model pond distribution: Corine landcover, the heterogeneity of the landcover, slope, road distance, distance to closest village and the human population density. Land cover heterogeneity was the most important driver for the distribution of fishponds. Areas used for agriculture with significant areas of natural vegetation were the most important predictors for the distribution of temporary ponds. In addition, areas covered by transitional woodland and scrub were important for the open cattle ponds. Bombina variegata was found predominantly in the temporary ponds (e.g. ponds created by cattle and buffalo, dirt road ponds and concrete ponds created for livestock drinking and Bufo bufo in fishponds. CONCLUSIONS/SIGNIFICANCE: Our Maxent models revealed that the highest probability of occurrence for amphibian ponds was in areas used as farmland. The traditional farming practices combined with a low level of infrastructure development produces a large number of amphibian ponds. The challenge is to harmonize economic development and the maintenance of high densities of ponds in these traditional rural landscapes.

  18. Assessing the Performance of two Stormwater Management Ponds in Waterloo, Ontario

    Science.gov (United States)

    Mulroy, K.; Stone, M.

    2009-05-01

    Stormwater runoff in urban areas represents a major pathway for pollutant transfer to receiving waters. Stormwater management (SWM) ponds are used as a best management practice to help mitigate the negative effects of stormwater. This study examines the performance of two SWM pond designs (conventional and extended detention) in Waterloo, Ontario, Canada. A mass balance approach is used to quantify the concentration of total phosphorus (TP), soluble reactive phosphorus (SRP) and total suspended solids (TSS) at the inlet(s) and outlet of each pond. These parameters were sampled and characterized for 30 baseflow observations and 10 stormflow events in order to calculate the trap efficiency for each pond. The results show that, baseflow reduction for all constituents was low for both ponds. Pond 33 (extended detention design) was a source of TP and SRP during baseflow periods with trap efficiencies of -34% and -61% respectively. Pond 45 (conventional design) retained 65% of influent TP and 36% SRP. Both ponds were sinks for TSS during baseflow periods with 61% and 48% of SS retained for Pond 33 and Pond 45 respectively. Retention during storm events was higher compared to baseflow periods. Pond 33 retained 11%, 40% and 66% of TP, SRP and TSS, whereas Pond 45 had a higher trap efficiency of 90%, 93% and 97% for TP, SRP and TSS. Trap efficiency of these constituents are governed by pH, temperature and dissolved oxygen, as well as sediment geochemistry, P speciation and cycling at the sediment-water interface. Additional research focusing on P cycling in SWM ponds is required to improve trap efficiencies through improved pond design.

  19. Patterns of Assemblage Structure Indicate a Broader Conservation Potential of Focal Amphibians for Pond Management.

    Science.gov (United States)

    Soomets, Elin; Rannap, Riinu; Lõhmus, Asko

    2016-01-01

    Small freshwater ponds host diverse and vulnerable biotic assemblages but relatively few conspicuous, specially protected taxa. In Europe, the amphibians Triturus cristatus and Pelobates fuscus are among a few species whose populations have been successfully restored using pond restoration and management activities at the landscape scale. In this study, we explored whether the ponds constructed for those two target species have wider conservation significance, particularly for other species of conservation concern. We recorded the occurrence of amphibians and selected aquatic macro-invertebrates (dragonflies; damselflies; diving beetles; water scavenger beetles) in 66 ponds specially constructed for amphibians (up to 8 years post construction) and, for comparison, in 100 man-made ponds (created by local people for cattle or garden watering, peat excavation, etc.) and 65 natural ponds in Estonia. We analysed nestedness of the species assemblages and its dependence on the environment, and described the co-occurrence patterns between the target amphibians and other aquatic species. The assemblages in all ponds were significantly nested, but the environmental determinants of nestedness and co-occurrence of particular species differed among pond types. Constructed ponds were most species-rich irrespective of the presence of the target species; however, T. cristatus was frequent in those ponds and rare elsewhere, and it showed nested patterns in every type of pond. We thus conclude that pond construction for the protected amphibians can serve broader habitat conservation aims in the short term. However, the heterogeneity and inconsistent presence of species of conservation concern observed in other types of ponds implies that long-term perspectives on pond management require more explicit consideration of different habitat and biodiversity values. We also highlight nestedness analysis as a tool that can be used for the practical task of selecting focal species for

  20. Sound management of sediment yields at the catchment scale by small detention ponds

    Science.gov (United States)

    Sikorska, A. E.; Wasilewicz, M.; Banasik, K.

    2012-04-01

    Keywords: small detention pond, sediment deposits, reservoir silting, urban catchment Globally observed land use and climate changes have a clear impact on the sediment yields deriving from the catchment. Released sediments may originate from different point and non-point sources. Thereby it is difficult to manage and reduce sediment loads directly at the source without undertaking detailed and expensive monitoring programs. Small detention ponds are therefore frequently used water management systems in urban settlements to improve water quality at the catchment scale. Such ponds located at the outlet of small basins allow reducing sediment loads downstream. Additionally, they capture sediment-associated contaminants as heavy metals, nutrients and micropollutants. On the other hand, a sedimentation within the pond may be a severe problem because it decreases over the time its retention capacity. This is especially significant for small detention ponds, where the siltation rate is high. These ponds can loose their total capacity already after few years of their exploitation when no dredging operations are considered. Unfortunately, maintenance costs of small ponds are expensive and usually not taken into account when planning and constructing such ponds. Consequently, many small detention ponds become inefficient after an entire use of their capacity. Therefore careful planning of maintenance options is essential to keep an effectiveness of such ponds on the expected level. Within presented here study we addressed the problem of silting small detention ponds and we assessed an applicability of such ponds to manage sediment yields discharged from small urban catchments. To this end, a periodic measurement of deposited sediments within a small detention pond (1.35 ha, 5 years old, Warsaw, Poland) has been undertaken. This pond receives a polluted runoff from a small urbanized basin (30 km2), for which no routine sediment measurement exists. The spatial sediment

  1. High frequency energy cascades in inviscid hydrodynamics

    Science.gov (United States)

    Costa, Adam Smith N.; de Araújo, J. M.; Cohen, Nir; Lucena, Liacir S.; Viswanathan, G. M.

    2014-04-01

    With the aim of gaining insight into the notoriously difficult problem of energy and vorticity cascades in high dimensional incompressible flows, we take a simpler and very well understood low dimensional analog and approach it from a new perspective, using the Fourier transform. Specifically, we study, numerically and analytically, how kinetic energy moves from one scale to another in solutions of the hyperbolic or inviscid Burgers equation in one spatial dimension (1D). We restrict our attention to initial conditions which go to zero as x→±∞. The main result we report here is a Fourier analytic way of describing the cascade process. We find that the cascade proceeds by rapid growth of a crossover scale below which there is asymptotic power law decay of the magnitude of the Fourier transform.

  2. Bifurcations analysis of turbulent energy cascade

    Energy Technology Data Exchange (ETDEWEB)

    Divitiis, Nicola de, E-mail: n.dedivitiis@gmail.com

    2015-03-15

    This note studies the mechanism of turbulent energy cascade through an opportune bifurcations analysis of the Navier–Stokes equations, and furnishes explanations on the more significant characteristics of the turbulence. A statistical bifurcations property of the Navier–Stokes equations in fully developed turbulence is proposed, and a spatial representation of the bifurcations is presented, which is based on a proper definition of the fixed points of the velocity field. The analysis first shows that the local deformation can be much more rapid than the fluid state variables, then explains the mechanism of energy cascade through the aforementioned property of the bifurcations, and gives reasonable argumentation of the fact that the bifurcations cascade can be expressed in terms of length scales. Furthermore, the study analyzes the characteristic length scales at the transition through global properties of the bifurcations, and estimates the order of magnitude of the critical Taylor-scale Reynolds number and the number of bifurcations at the onset of turbulence.

  3. Emergence of event cascades in inhomogeneous networks

    CERN Document Server

    Onaga, Tomokatsu

    2016-01-01

    There is a commonality among contagious diseases, tweets, urban crimes, nuclear reactions, and neuronal firings that past events facilitate the future occurrence of events. The spread of events has been extensively studied such that the systems exhibit catastrophic chain reactions if the interaction represented by the ratio of reproduction exceeds unity; however, their subthreshold states for the case of the weaker interaction are not fully understood. Here, we report that these systems are possessed by nonstationary cascades of event-occurrences already in the subthreshold regime. Event cascades can be harmful in some contexts, when the peak-demand causes vaccine shortages, heavy traffic on communication lines, frequent crimes, or large fluctuations in nuclear reactions, but may be beneficial in other contexts, such that spontaneous activity in neural networks may be used to generate motion or store memory. Thus it is important to comprehend the mechanism by which such cascades appear, and consider controlli...

  4. Cascade enzymatic reactions for efficient carbon sequestration.

    Science.gov (United States)

    Xia, Shunxiang; Zhao, Xueyan; Frigo-Vaz, Benjamin; Zheng, Wenyun; Kim, Jungbae; Wang, Ping

    2015-04-01

    Thermochemical processes developed for carbon capture and storage (CCS) offer high carbon capture capacities, but are generally hampered by low energy efficiency. Reversible cascade enzyme reactions are examined in this work for energy-efficient carbon sequestration. By integrating the reactions of two key enzymes of RTCA cycle, isocitrate dehydrogenase and aconitase, we demonstrate that intensified carbon capture can be realized through such cascade enzymatic reactions. Experiments show that enhanced thermodynamic driving force for carbon conversion can be attained via pH control under ambient conditions, and that the cascade reactions have the potential to capture 0.5 mol carbon at pH 6 for each mole of substrate applied. Overall it manifests that the carbon capture capacity of biocatalytic reactions, in addition to be energy efficient, can also be ultimately intensified to approach those realized with chemical absorbents such as MEA. PMID:25708541

  5. Remediation of the Sillamae Radioactive Tailings Pond, Estonia

    International Nuclear Information System (INIS)

    The paper presents experiences gained and progress achieved during the ongoing Sillamaee Radioactive Tailings Pond Remediation Project. The Sillamaee tailings pond covering ca. 50 ha is located next to the shoreline of the Baltic Sea near Sillamaee town in Estonia. Tailings disposal included mill tailings from uranium ore processing (1953-1977), enriched uranium refining (1977- 1990), from rare earth elements processing (since 1970; tailings disposal ended 2003), black shale processing (1948-1953) and liquid oil-shale ashes from the local power plant. Initial environmental and geotechnical investigations identified insufficient safety of the tailings pond for radiological, environmental and geotechnical reasons. Contaminated seepage was entering the Baltic Sea. The 25 m high northern tailings dam was affected by marine erosion and the stability of the dam was found to be insufficient. Therefore the multi-national Sillamaee Radioactive Tailings Pond Remediation Programme was launched in 1998 jointly financed by North European Countries (NEFCO), EU and Estonia. The remediation project included the following crucial remediation steps: Drillings and samplings including geotechnical, (hydro-)geological and environmental investigations (2000-2001); relocation of mine wastes and contaminated soils from the surrounding area onto the tailings pond for interim covering (2000-2003); initial stabilization measures (2001-2003) including a 1080 m long shore protection embankment along the shoreline of the Baltic Sea, a 720 m long pile grillage for stabilizing the northern dam including two rows of 15 m or 18 m deep continuous flight auger piles, a 580 m long and 12-18 m deep cut-off wall, a deep gravel-filled drainage ditch (520 m, up to 12 m deep) and a deep drainage trench. Reshaping of the dams with respect to long term dam stability and contouring of the pond area with respect to long term settlement portions lasted from 2003 till 2004 building up a ridge-type surface

  6. Biomass and productivity of trematode parasites in pond ecosystems.

    Science.gov (United States)

    Preston, Daniel L; Orlofske, Sarah A; Lambden, Jason P; Johnson, Pieter T J

    2013-05-01

    1. Ecologists often measure the biomass and productivity of organisms to understand the importance of populations and communities in the flow of energy through ecosystems. Despite the central role of such studies in the advancement of freshwater ecology, there has been little effort to incorporate parasites into studies of freshwater energy flow. This omission is particularly important considering the roles that parasites sometimes play in shaping community structure and ecosystem processes. 2. Using quantitative surveys and dissections of over 1600 aquatic invertebrate and amphibian hosts, we calculated the ecosystem-level biomass and productivity of trematode parasites alongside the biomass of free-living aquatic organisms in three freshwater ponds in California, USA. 3. Snails and amphibian larvae, which are both important intermediate trematode hosts, dominated the dry biomass of free-living organisms across ponds (snails = 3.2 g m(-2); amphibians = 3.1 g m(-2)). An average of 33.5% of mature snails were infected with one of six trematode taxa, amounting to a density of 13 infected snails m(-2) of pond substrate. Between 18% and 33% of the combined host and parasite biomass within each infected snail consisted of larval trematode tissue, which collectively accounted for 87% of the total trematode biomass within the three ponds. Mid-summer trematode dry biomass averaged 0.10 g m(-2), which was equal to or greater than that of the most abundant insect orders (coleoptera = 0.10 g m(-2), odonata = 0.08 g m(-2), hemiptera = 0.07 g m(-2) and ephemeroptera = 0.03 g m(-2)). 4. On average, each trematode taxon produced between 14 and 1660 free-swimming larvae (cercariae) infected snail(-1) 24 h(-1) in mid-summer. Given that infected snails release cercariae for 3-4 months a year, the pond trematode communities produced an average of 153 mg m(-2) yr(-1) of dry cercarial biomass (range = 70-220 mg m(-2) yr(-1)). 5. Our results suggest that a significant amount of energy

  7. Alfven wave cascades in a tokamak

    International Nuclear Information System (INIS)

    Experiments designed for generating internal transport barriers in the plasmas of the Joint European Torus [JET, P. H. Rebut et al., Proceedings of the 10th International Conference, Plasma Physics and Controlled Nuclear Fusion, London (International Atomic Energy Agency, Vienna, 1985), Vol. I, p. 11] reveal cascades of Alfven perturbations with predominantly upward frequency sweeping. These experiments are characterized by a hollow plasma current profile, created by lower hybrid heating and current drive before the main heating power phase. The cascades are driven by ions accelerated with ion cyclotron resonance heating (ICRH). Each cascade consists of many modes with different toroidal mode numbers and different frequencies. The toroidal mode numbers vary from n=1 to n=6. The frequency starts from 20 to 90 kHz and increases up to the frequency range of toroidal Alfven eigenmodes. In the framework of ideal magnetohydrodynamics (MHD) model, a close correlation is found between the time evolution of the Alfven cascades and the evolution of the Alfven continuum frequency at the point of zero magnetic shear. This correlation facilitates the study of the time evolution of both the Alfven continuum and the safety factor, q(r), at the point of zero magnetic shear and makes it possible to use Alfven spectroscopy for studying q(r). Modeling shows that the Alfven cascade occurs when the Alfven continuum frequency has a maximum at the zero shear point. Interpretation of the Alfven cascades is given in terms of a novel-type of energetic particle mode localized at the point where q(r) has a minimum. This interpretation explains the key experimental observations: simultaneous generation of many modes, preferred direction of frequency sweeping, and the absence of strong continuum damping

  8. Piscivores, Trophic Cascades, and Lake Management

    Directory of Open Access Journals (Sweden)

    Ray W. Drenner

    2002-01-01

    Full Text Available The concept of cascading trophic interactions predicts that an increase in piscivore biomass in lakes will result in decreased planktivorous fish biomass, increased herbivorous zooplankton biomass, and decreased phytoplankton biomass. Though often accepted as a paradigm in the ecological literature and adopted by lake managers as a basis for lake management strategies, the trophic cascading interactions hypothesis has not received the unequivocal support (in the form of rigorous experimental testing that might be expected of a paradigm. Here we review field experiments and surveys, testing the hypothesis that effects of increasing piscivore biomass will cascade down through the food web yielding a decline in phytoplankton biomass. We found 39 studies in the scientific literature examining piscivore effects on phytoplankton biomass. Of the studies, 22 were confounded by supplemental manipulations (e.g., simultaneous reduction of nutrients or removal of planktivores and could not be used to assess piscivore effects. Of the 17 nonconfounded studies, most did not find piscivore effects on phytoplankton biomass and therefore did not support the trophic cascading interactions hypothesis. However, the trophic cascading interactions hypothesis also predicts that lake systems containing piscivores will have lower phytoplankton biomass for any given phosphorus concentration. Based on regression analyses of chlorophyll�total phosphorus relationships in the 17 nonconfounded piscivore studies, this aspect of the trophic cascading interactions hypothesis was supported. The slope of the chlorophyll vs. total phosphorus regression was lower in lakes with planktivores and piscivores compared with lakes containing only planktivores but no piscivores. We hypothesize that this slope can be used as an indicator of “functional piscivory” and that communities with extremes of functional piscivory (zero and very high represent classical 3- and 4-trophic level

  9. Cascading Quantum Light-Matter Interfaces

    OpenAIRE

    Namazi, Mehdi; Mittiga, Thomas; Kupchak, Connor; Figueroa, Eden

    2015-01-01

    The ability to interface multiple optical quantum devices is a key milestone towards the development of future quantum networks that are capable of sharing and processing quantum information encoded in light. One of the requirements for any node of these quantum networks will be cascadability, i.e. the ability to drive the input of a node using the output of another node. Here, we report the cascading of quantum light-matter interfaces by storing few-photon level pulses of light in warm vapor...

  10. Cascade Speed Control Of Dc Motor

    OpenAIRE

    Anagha, Ranjith K; Anand C.P; Rahul Das; Anusha A.S

    2014-01-01

    Abstract: This paper presents a MATLAB aided Cascade designed controller to control and monitor the DC motor speed. First, design the driver circuit of the DC motor and use the microcontroller PIC16F877A to collect the feedback signals from the current sensor and optical encoder. The measured speed and current are serially transmitted to PC using RS232. By the MATLAB aided cascade controller, where inner loop is the current loop and outer loop is the speed loop, the parameters are adjusted to...

  11. Cascaded Multicell Trans-Z-Source Inverters

    DEFF Research Database (Denmark)

    Li, Ding; Chiang Loh, Poh; Zhu, Miao;

    2013-01-01

    Inverters with high-output voltage gain usually face the problem of high-input current flowing through their components. The problem might further be exaggerated if the inverters use high-frequency magnetic devices like transformers or coupled inductors. Leakage inductances of these devices must...... strictly be small to prevent overvoltages caused by switching of their winding currents. To avoid these related problems, cascaded trans-Z-source inverters are proposed. They use multiple magnetic cells in an alternately cascading pattern rather than a single magnetic cell with large turns ratio...

  12. Dynamics of Soliton Cascades in Fiber Amplifiers

    CERN Document Server

    Arteaga-Sierra, F R; Agrawal, Govind P

    2016-01-01

    We study numerically the formation of cascading solitons when femtosecond optical pulses are launched into a fiber amplifier with less energy than required to form a soliton of equal duration. As the pulse is amplified, cascaded fundamental solitons are created at different distances, without soliton fission, as each fundamental soliton moves outside the gain bandwidth through the Raman-induced spectral shifts. As a result, each input pulse creates multiple, temporally separated, ultrashort pulses of different wavelengths at the amplifier output. The number of pulses depends not only on the total gain of the amplifier but also on the width of input pulses.

  13. Energy cascade in internal wave attractors

    CERN Document Server

    Brouzet, Christophe; Joubaud, Sylvain; Sibgatullin, Ilias; Dauxois, Thierry

    2016-01-01

    One of the pivotal questions in the dynamics of the oceans is related to the cascade of mechanical energy in the abyss and its contribution to mixing. Here, we propose internal wave attractors in the large amplitude regime as a unique self-consistent experimental and numerical setup that models a cascade of triadic interactions transferring energy from large-scale monochro-matic input to multi-scale internal wave motion. We also provide signatures of a discrete wave turbulence framework for internal waves. Finally, we show how beyond this regime, we have a clear transition to a regime of small-scale high-vorticity events which induce mixing. Introduction.

  14. Magnetic properties of marine magnetotactic bacteria in a seasonally stratified coastal pond (Salt Pond, MA, USA)

    Science.gov (United States)

    Moskowitz, Bruce M.; Bazylinski, Dennis A.; Egli, Ramon; Frankel, Richard B.; Edwards, Katrina J.

    2008-07-01

    Magnetic properties of suspended material in the water columns of freshwater and marine environments provide snapshots of magnetic biomineralization that have yet to be affected by the eventual time-integration and early diagenetic effects that occur after sediment deposition. Here, we report on the magnetism, geochemistry and geobiology of uncultured magnetite- and greigite-producing magnetotactic bacteria (MB) and magnetically responsive protists (MRP) in Salt Pond (Falmouth, MA, USA), a small coastal, marine basin (~5 m deep) that becomes chemically stratified during the summer months. At this time, strong inverse O2 and H2S concentration gradients form in the water column and a well-defined oxic-anoxic interface (OAI) is established at a water depth of about 3.5 m. At least four morphological types of MB, both magnetite and greigite producers, and several species of magnetically responsive protists are found associated with the OAI and the lower sulphidic hypolimnion. Magnetic properties of filtered water were determined through the water column across the OAI and were consistent with the occurrence of magnetite- and greigite-producing MB at different depths. Sharp peaks in anhysteretic remanent magnetization (ARM) and saturation isothermal remanent magnetization (SIRM) and single-domain (SD) values of ARM/SIRM occur within the OAI corresponding to high concentrations of MB and MRP with magnetically derived cell densities of 104-106 ml-1. Low-temperature (II) in the water column. However, below the OAI, magnetic minerals constitute a much larger fraction of the total dissolved Fe(II) ranging from 13.6 to 32.2 per cent depending on magnetic mineralogy. Most of this iron is possibly in the form of nanophase magnetic particles, possibly associated with biologically induced mineralization processes occurring below the OAI. Still, the OAI is a narrow but intense zone of SD particle production. Despite using just a small fraction of available dissolved Fe(II) in the

  15. Habitat cascades: the conceptual context and global relevance of facilitation cascades via habitat formation and modification.

    Science.gov (United States)

    Thomsen, Mads S; Wernberg, Thomas; Altieri, Andrew; Tuya, Fernando; Gulbransen, Dana; McGlathery, Karen J; Holmer, Marianne; Silliman, Brian R

    2010-08-01

    The importance of positive interactions is increasingly acknowledged in contemporary ecology. Most research has focused on direct positive effects of one species on another. However, there is recent evidence that indirect positive effects in the form of facilitation cascades can also structure species abundances and biodiversity. Here we conceptualize a specific type of facilitation cascade-the habitat cascade. The habitat cascade is defined as indirect positive effects on focal organisms mediated by successive facilitation in the form of biogenic formation or modification of habitat. Based on a literature review, we demonstrate that habitat cascades are a general phenomenon that enhances species abundance and diversity in forests, salt marshes, seagrass meadows, and seaweed beds. Habitat cascades are characterized by a hierarchy of facilitative interactions in which a basal habitat former (typically a large primary producer, e.g., a tree) creates living space for an intermediate habitat former (e.g., an epiphyte) that in turn creates living space for the focal organisms (e.g., spiders, beetles, and mites). We then present new data on a habitat cascade common to soft-bottom estuaries in which a relatively small invertebrate provides basal habitat for larger intermediate seaweeds that, in turn, generate habitat for focal invertebrates and epiphytes. We propose that indirect positive effects on focal organisms will be strongest when the intermediate habitat former is larger and different in form and function from the basal habitat former. We also discuss how humans create, modify, and destroy habitat cascades via global habitat destruction, climatic change, over-harvesting, pollution, or transfer of invasive species. Finally, we outline future directions for research that will lead to a better understanding of habitat cascades. PMID:21558196

  16. Cell Molecular Dynamics for Cascades (CMDC): A new tool for cascade simulation

    International Nuclear Information System (INIS)

    We present a new Molecular Dynamics (MD) scheme for the simulation of cascades: Cell Molecular Dynamics for Cascades (CMDC). It is based on the decomposition of the material in nanometric cells which are added and removed on the fly from the MD simulation and the dynamics of which are treated with a local time step. An acceleration of several orders of magnitude is observed compared to standard calculation. The capacity of the method is demonstrated on the test cases of 60 keV He implantation and self-cascades in iron up to 1.8 MeV

  17. Nitrogen and phosphorus cycling in shrimp ponds and the measures for sustainable management.

    Science.gov (United States)

    Xia, L Z; Yang, L Z; Yan, M C

    2004-01-01

    Six ponds of age 3 were selected 45 km north from Suzhou in the Tailake region, and research conducted on nitrogen and phosphorus cycling in P. vannanmei (Penaeus vannanme) ponds and M. nipponense (Macrobrachium nipponense) hatchery ponds under normal management. Two treatments each had three replications. The results confirmed that feed was the major path of nitrogen and phosphorus input, each accounted for 61.24% (193.81 kg ha(-1)) and 81.08% (45.20 kg ha(-1)) of the total nitrogen and phosphorus input for P. vannanme ponds; the values for M. nipponense ponds were 43.93% (86.31 kg ha(-1)) and 57.67% (14.61 kg ha(-1)), respectively. Water pumped into ponds contributed on average 83.57 kg ha(-1) nitrogen and 8.48 kg ha(-1) phosphorus for P. vannanmei ponds, and 87.48 kg ha(-1) nitrogen and 7.00 kg ha(-1) phosphorus for M. nipponense hatchery ponds. Shrimp harvest recovered 102.81 kg ha(-1) nitrogen (32.94% of the total nitrogen input) and 7.94 kg ha(-1) phosphorus (14.23% of the total phosphorus input) for P. vannanme ponds; and 43.94 kg ha(-1) nitrogen and 4.46 kg ha(-1) phosphorus for M. nipponense hatchery ponds. The sum of nitrogen losses through volatilization, denitrification and sedimentation was 173.62 and 122.39 kg ha(-1), 54.86% and 62.29% of the total nitrogen input for P. vannanme ponds and M. nipponense hatchery ponds, respectively. Sediment accumulated 41.46 and 14.63 kg ha(-1) phosphorus, 74.37% and 64.85% of the total phosphorus input for P. vannanm ponds and M. nipponense hatchery ponds. Draining and seeping caused 40.06 kg ha(-1) nitrogen (12.66% of total nitrogen input) and 6.36 kg ha(-1) phosphorus (11.40% of total phosphorus input) loss to the surrounding water from P. vannanme ponds in 114 days; 30.14 kg ha(-1) nitrogen (15.34% of the total input) and 4.45 kg ha(-1) phosphorus (17.57% of the total input) to channel water from M. nipponense hatchery ponds in 87 days, respectively. Countermeasures for sustainable pond management include

  18. Fate and effects of esfenvalerate in agricultural ponds

    DEFF Research Database (Denmark)

    Samsøe-Petersen, L.; Gutavson, K.; Madsen, T.;

    2001-01-01

    The fate of esfenvalerate was investigated by sampling and chemical analysis after spraying of an artificial pond (25 g a.i./ha) and in the laboratory with [C-14]esfenvalerate by trapping of (CO2)-C-14 and fractionation of the sediment. The effects were investigated on pelagic communities in...... enclosures in a natural lake and in the laboratory on surface (Cymatia coleoptrata) and sediment (Chironomus riparius) insects. The latter were used in sediment-plus-water and in water-only tests, measuring effects on emergence and mortality. The measurements in the artificial pond indicated exposure...... concentrations in the surface microlayer, water column, and sediment of 0.4 mug/L. 0.05 mug/L, and 9 mug/kg dry weight, respectively, two weeks after application. The degradation studies showed a limited mineralization (26.5%) of [chlorophenyl-C-14]esfenvalerate during 112 d. Part of the substance was...

  19. Anthropogenic climate change impacts on ponds: a thermal mass perspective

    Directory of Open Access Journals (Sweden)

    John Matthews

    2010-12-01

    Full Text Available Small freshwater aquatic lentic systems (lakes and ponds are sensitive to anthropogenic climate change through shifts in ambient air temperatures and patterns of precipitation. Shifts in air temperatures will influence lentic water temperatures through convection and by changing evaporation rates. Shifts in the timing, amount, and intensity of precipitation will alter the thermal mass of lentic systems even in the absence of detectable ambient air temperature changes. These effects are likely to be strongest in ponds (standing water bodies primarily mixed by temperature changes than by wind, for whom precipitation makes up a large component of inflows. Although historical water temperature datasets are patchy for lentic systems, thermal mass effects are likely to outweigh impacts from ambient air temperatures in most locations and may show considerable independence from those trends. Thermal mass-induced changes in water temperature will thereby alter a variety of population- and community-level processes in aquatic macroinvertebrates.

  20. Detention Pond Sediment Accumulation Prediction using Monte Carlo Simulation

    Directory of Open Access Journals (Sweden)

    Supiah Shamsudin

    2012-01-01

    Full Text Available Problem statement: A study in Malaysia had been carried out to predict the sediment accumulation in urban detention ponds. Suspended sediment is pollutant of primary concern to the river that results in adverse environmental effect. Detention pond becomes a practical approach to this problem. Suspended sediment that settled in stormwater detention pond, can bring effect to the detention pond functions. Questions were raised on how certain were the observed and predicted values of sediment depth and load accumulation estimations. Secondly the question was what the sediment accumulation be in the next 100 years. The uncertainties of sediments estimation vary greatly due to the hydrological variability and rainfall random nature obtain the relationship between flow discharge and suspended sediment rate using on-site data collection at UTM and Ledang Heights, Nusajaya. Predict accumulated sediment loads and depth from MUSLE over 10-100 years. Analyze the uncertainties of sediment loads and depth using Monte Carlo Simulation (MCS combining normal distribution. Obtain the maximum probability of occurrence of sediment loads and depth in the detention pond. Approach: Modified Universal Soil Loss Equation (MUSLE and Trap Efficiency (TE Method was applied to predict sediment accumulation. This uncertainty of sediment loads and depth was carried out using Monte Carlo Simulation (MCS Method. The water samples were collected for suspended solids data and other water quality parameters at Ledang Heights, Nusajaya, Johor and University Technology Malaysia (UTM, Johor. Sampling station were randomly selected at the inlet and outlet of the detention pond. The hydrological parameters such as flow and velocity were also collected. Results: The simulation results showed the maximum probability of occurrence value for observed sediment loads and sediment depth from Ledang Heights were 0.0062 tons (16.5% and 0.0005 mm (17.5% respectively. The maximum probability of

  1. Microbial Phosphorus Removal in Waste Stabilisation Pond Wastewater Treatment Systems

    OpenAIRE

    Mbwele, Lydia Ambakisye

    2006-01-01

    Waste Stabilisation Ponds (WSPs) are characterised by low phosphorus (P) removal capacity. Heterotrophic bacteria are principal microbial agents in WSPs in addition to algae. As treatment proceeds in WSPs, algal growth increases and pH rises, this has lead to believe that P removal is mainly through sedimentation as organic P algal biomass and precipitation as inorganic P. In activated sludge treatment plants (AS), microbial P removal has been improved and is termed as enhanced biological pho...

  2. Mobility of trace metals in retention pond sediments

    OpenAIRE

    Durand, C.; Ruban, V.; A. AMBLES

    2004-01-01

    This paper presents the results of a study on tracez mobility on the sediments of several road and urban infiltration / decantation ponds in France ; the trace metal concentrations are indeed high. The potential mobility of trace metals (cadmium, nickel, chromium, copper, lead and zinc) was evaluated by application of the sequential extraction BCR protocol. Results have been compared with those from the IHSS protocol, which allows for the extraction of various form of organic matter. Cadmium ...

  3. Pond culture of seaweed Sargassum hemiphyllum in southern China

    Institute of Scientific and Technical Information of China (English)

    YU Zonghe; HU Chaoqun; SUN Hongyan; LI Haipeng; PENG Pengfei

    2013-01-01

    The seaweed Sargassum hemiphyllum is widely distributed throughout the coastal waters of Asia and has high commercial value.In recent years,its natural biomass has declined due to over-exploitation and environmental pollution.To seek for a feasible way to culture this seaweed efficiently,we designed a simple long-line system in a shrimp pond for the culture during winter,and the growth and nutritional composition of the seaweed were examined.Results show that the culture system was durable and flexible allowing S.hemiphyllum to grow vertically offthe muddy bottom of the pond.Although the length of pondcultured S.hemiphyllum was inhibited by water depth,the weight-specific growth rate ((1.65±0.17)%/d)was nearly three times higher than that of wild plants ((0.62±0.19)%/d).The crude protein (6.92%±0.88%)and ash content (21.52%±0.07%) of the pond-cultured seaweed were significantly lower than those of the wild plants (9.38%±0.43% and 26.93%±0.07%,respectively); however,crude fat (1.01%±0.04%) was significantly higher than that of the wild plants (0.87%±0.02%).In addition,the nutritional composition of both pond-cultured and wild S.hemiphyllum was comparable to or even higher than those of other common seaweeds being used as food and/or aquaculture fodder.Future studies shall be focused on the impact of environmental parameters on its growth and nutritional composition.

  4. Pond culture of seaweed Sargassum hemiphyllum in southern China

    Science.gov (United States)

    Yu, Zonghe; Hu, Chaoqun; Sun, Hongyan; Li, Haipeng; Peng, Pengfei

    2013-03-01

    The seaweed Sargassum hemiphyllum is widely distributed throughout the coastal waters of Asia and has high commercial value. In recent years, its natural biomass has declined due to over-exploitation and environmental pollution. To seek for a feasible way to culture this seaweed efficiently, we designed a simple long-line system in a shrimp pond for the culture during winter, and the growth and nutritional composition of the seaweed were examined. Results show that the culture system was durable and flexible allowing S. hemiphyllum to grow vertically off the muddy bottom of the pond. Although the length of pondcultured S. hemiphyllum was inhibited by water depth, the weight-specific growth rate ((1.65±0.17)%/d) was nearly three times higher than that of wild plants ((0.62±0.19)%/d). The crude protein (6.92%±0.88%) and ash content (21.52%±0.07%) of the pond-cultured seaweed were significantly lower than those of the wild plants (9.38%±0.43% and 26.93%±0.07%, respectively); however, crude fat (1.01%±0.04%) was significantly higher than that of the wild plants (0.87%±0.02%). In addition, the nutritional composition of both pond-cultured and wild S. hemiphyllum was comparable to or even higher than those of other common seaweeds being used as food and/or aquaculture fodder. Future studies shall be focused on the impact of environmental parameters on its growth and nutritional composition.

  5. Anaerobic ponds for domestic wastewater treatment in temperate climates

    OpenAIRE

    Cruddas, Peter

    2014-01-01

    Energy demand, greenhouse gas emissions, and operational costs are continuing to rise year on year in the wastewater treatment sector, with traditional treatment options unable to provide sustainable solutions to increasing volumes and tightening quality standards. Current processes produce inherent fugitive greenhouse gas (GHG) emissions, whilst also generating large quantities of sludge for disposal. Anaerobic ponds (APs) are natural wastewater treatment processes that have t...

  6. Modelling the fate of organic micropollutants in stormwater ponds

    OpenAIRE

    Vezzaro, Luca; Eriksson, Eva; Ledin, Anna; Mikkelsen, Peter Steen

    2011-01-01

    Urban water managers need to estimate the potential removal of organic micropollutants (MP) in stormwater treatment systems to support MP pollution control strategies. This study documents how the potential removal of organic MP in stormwater treatment systems can be quantified by using multimedia models. The fate of four different MP in a stormwater retention pond was simulated by applying two steady-state multimedia fate models (EPI Suite and SimpleBox) commonly applied in chemical risk ass...

  7. Chromate abatement in the Y-12 Plant's New Hope Pond

    International Nuclear Information System (INIS)

    Results are reported from a 15-months field study that utilized four nonchromate-based water-treatment programs in 16 low-temperature (less than 1000F) cooling towers using corrosion and deposition studies, microbiological control, and plant effluent creek analyses as evaluation parameters. The study succeeded in bringing the chromate content of effluent of the New Hope Pond at the Oak Ridge Y-12 Plant to the limits established by the Environmental Protection Agency. (auth)

  8. Predator-prey size interaction in tropical ponds

    OpenAIRE

    Claude Gascon

    1989-01-01

    An experiment was set-up to see in mortality inflicted by tadpole predators depends on prey and predator sizes. Fish and dragonfly larvae were used as predators and two size classes of Osteocephalus taurinus tadpoles as prey. Results show that the effect of predators is dependent on the size structure of the prey population. Furthermore, dragonfly larvae are more voracious predators than the fish used in the experiment. Both predators occur in natural ponds where Osteocephalus taurinus lays i...

  9. Migratory waterbirds at artificial ponds in NW Tenerife (Canary Islands)

    OpenAIRE

    Rodríguez, Beneharo; Rodríguez, Airam

    2011-01-01

    Human settlements have mainly destroyed natural habitat but also led to the creation of new ones, some of them suitable for wildlife. In this line, the construction of artificial ponds for irrigation of agricultural land or on golf courses may also provide new habitats for waterbirds. Large freshwater wetlands are absent or very scarce on the Canary Islands, so both migratory and resident waterbirds usually use artificial water bodies as feeding or nesting sites. We compared monthly censuses ...

  10. From tailings pond 1 to Wapisiw Lookout, Suncor celebrates reclamation milestone

    Energy Technology Data Exchange (ETDEWEB)

    Jaremko, D.

    2010-12-15

    Suncor Energy is the first company to achieve the restoration of a tailings pond to a natural setting. Its Tailings Pond 1 is now known as Wapisiw Lookout, a solid surface that accommodates 630,000 shrubs and trees planted earlier in 2010. Ultimately, the area will look very similar to the natural landscape of the boreal forest. Suncor created the 220 hectare Tailings Pond 1 in 1967 when it was the only way to produce bitumen. It was part of 8 tailings ponds that covered a combined 3,154 hectares. Pond 1 was decommissioned in December 2006 with the removal of mature fine tailings (MFT). The greatest challenge facing Suncor was to create a solid surface from the sludge. Suncor backfilled the site with 30 million tonnes of reclaimed tailings sand. The site undergoes regular soil, water and vegetation assessments. Much of the MFT from Pond 1 was moved to another tailings ponds that is better suited for long-term storage and treatment. This article also described Suncor's tailings reduction operations (TRO), in which MFTs are mixed with a polymer flocculant and then deposited in thin layers over sand banks with shallow slopes to produce a dry material that can be reclaimed instead of being moved to another location. Because of its TRO, Suncor will not be building any new tailings ponds. Pond 5 is the next tailings pond targeted for reclamation. 9 figs.

  11. The effect of sunny area ratios on the thermal performance of solar ponds

    International Nuclear Information System (INIS)

    Highlights: • The effect of sunny area ratio on model solar ponds in different geometries. • The sunny area ratio was calculated for 8 different cases. • The efficiency of the model solar pond was determined for 8 different cases. • The energy efficiencies of the solar pond are affected by the sizes of the solar pond, strongly. • The results help to select the sizes of the solar pond before construction. - Abstract: In this study, we investigated the effect of the sunny area ratios on thermal efficiency of model solar pond for different cases in Adiyaman, Turkey. For this purpose, we modeled the solar ponds to compute theoretical sunny area ratios of the zones and temperature distributions in order to find the performance of the model solar ponds. Incorporating the finite difference approach, one and two dimensional heat balances were written for inner zones and insulation side walls. Through, careful determination of the dimensions, insulation parameter and incoming solar radiation reaching the storage zone increased the efficiency of the solar pond. The efficiencies of the model solar pond were determined for case1a–2a–3a–4a to be maximum 14.93%, 20.42%, 23.51% and 27.84%, and for case1b–2b–3b–4b to be maximum 12.65%, 16.76%, 21.37% and 23.30% in August, respectively. With the increase of the sunny area ratio, the performance of the solar pond significantly increased. However, with the increasing rate of the surface area, performance increase rate decreased gradually. The results provide a strong perspective to determine the dimensions of the solar pond before starting the project of a solar pond

  12. Endohelminths of European pond turtle Emys orbicularis in Southwest Iran.

    Science.gov (United States)

    Shayegh, Hossein; Rajabloo, Mohammad; Gholamhosseini, Amin; Mootabi Alavi, Amir; Salarian, Parisa; Zolfaghari, Ali

    2016-03-01

    Very little is known about parasitic diseases of European pond turtles (Emys orbicularis) in Iran. The objective of this study is to examine parasitic fauna of European pond turtles collected from Fars province, southwest Iran. Carcasses of turtles (n = 52) which died during dredging procedure are collected from earthen fishery basins in Zarghan region. They have been died earlier during dredging procedure in different farms. Three species of helminths in total were found in gastrointestinal tract, including two nematodes (Serpinema microcephalus and Falcaustra araxiana) and one digenean trematod (Telorchis assula). Large intestines of all examined turtles were infected by F. araxiana (100 %, Mean intensity = 18) and this nematode were also found in gastric nodules. Nine turtles (17.3 %, 3 male, 6 female, Mean intensity = 3) were infected with Serpinema microcephalus. T. assula were found in 25 turtles (48.07 %, 5 male, 20 female, mean intensity = 5). Helminths were not found in any examined organs and no ectoparasite found eighter. F. araxiana is the most prevalent nematode in European pond turtles. Detection of Serpinema.microcephalus is in agreement with the fact which this parasite is common parasite of turtles in all over the world. T. assula might be transmitted between variety of reptiles so presence of the trematod should be considered as a risk factor for other reptiles. PMID:27065624

  13. Little River Pond Mill a wind-powered lagoon aerator

    International Nuclear Information System (INIS)

    The Little River Pond Mill is a wind-driven surface aerator designed to be used in facultative wastewater treatment plants. The aerator consists of an eight-blade wind turbine which is mounted to a gear box that transmits torque through the shaft to the impeller. A swing tail rotates the turbine into the wind and stabilizes the unit in high winds. This study was designed to investigate how the Little River Pond Mill operated in a lagoon environment, how it affected the performance of the lagoon, and to measure the oxygen transfer rate for a field-determined wind speed. Strong mixing capabilities have been observed in both the dugout and the lagoon installations even at low windspeeds. With the installation of the aerator there was a reduction in BOD and NH3N. The oxygen transfer rate was found to be 1.47 g O2/W h at an average wind speed of 19 km/h. Due to the Pond Mill's low power requirement, this aeration efficiency has been rated as 'quite reasonable' for this wind speed. 5 refs., 10 figs

  14. Interpretation of ponded infiltration data using numerical experiments

    Directory of Open Access Journals (Sweden)

    Dohnal Michal

    2016-09-01

    Full Text Available Ponded infiltration experiment is a simple test used for in-situ determination of soil hydraulic properties, particularly saturated hydraulic conductivity and sorptivity. It is known that infiltration process in natural soils is strongly affected by presence of macropores, soil layering, initial and experimental conditions etc. As a result, infiltration record encompasses a complex of mutually compensating effects that are difficult to separate from each other. Determination of sorptivity and saturated hydraulic conductivity from such infiltration data is complicated. In the present study we use numerical simulation to examine the impact of selected experimental conditions and soil profile properties on the ponded infiltration experiment results, specifically in terms of the hydraulic conductivity and sorptivity evaluation. The effect of following factors was considered: depth of ponding, ring insertion depth, initial soil water content, presence of preferential pathways, hydraulic conductivity anisotropy, soil layering, surface layer retention capacity and hydraulic conductivity, and presence of soil pipes or stones under the infiltration ring. Results were compared with a large database of infiltration curves measured at the experimental site Liz (Bohemian Forest, Czech Republic. Reasonably good agreement between simulated and observed infiltration curves was achieved by combining several of factors tested. Moreover, the ring insertion effect was recognized as one of the major causes of uncertainty in the determination of soil hydraulic parameters.

  15. Application of Constructed Wetlands on Wastewater Treatment for Aquaculture Ponds

    Institute of Scientific and Technical Information of China (English)

    LI Gu; WU Zhenbin; CHENG Shuiping; LIANG Wei; HE Feng; FU Guiping; ZHONG Fei

    2007-01-01

    A group of constructed wetlands (CWs) were applied to the recirculating aquaculture system. This study assessed the performance of CWs in treating the aquaculture wastewater, examined the water quality condition of aquaculture ponds and the growth and the survival rate of "target" species(Ictalurus punctatus and Megalobrama amblycephala). The results showed that CWs were effective on reducing the concentrations of 5-day biochemical oxygen demand (BOD5, at 70.5%), total suspended solids (TSS, at 81.9%),chlorophyll a (Chl-a, at 91.9%), ammonium (NH4+, at 61.5%) and nitrate nitrogen (NO3--N, at 68.0%). Effect of CWs on phosphate (PO43- -P) removal was relatively lower (at 20.0%). The concentrations of BOD5, TSS, Chl-a, NH4+ and TN, TP in the recirculating culture pond were significantly lower than that in the control pond( p < 0.05 ). CWs could help to increase total yield, survival rate of the "target" species and significantly decrease feed conversion ratio ( p < 0.05 ).

  16. Performance evaluation of a tailings pond seepage collection system

    Energy Technology Data Exchange (ETDEWEB)

    Yasuda, N.; Thomson, N.R. [Waterloo Univ., ON (Canada). Dept. of Civil and Environmental Engineering; Barker, J.F. [Waterloo Univ., ON (Canada). Dept. of Earth and Environmental Sciences

    2010-12-15

    This paper presented a study evaluating the effectiveness of a seepage collection system at a large tailings pond at an oilsands mining operation. The 11-kilometre-long containment dyke that surrounds the tailings pond was constructed from permeable tailings sand. To collect process-affected water (PAW), the dyke was equipped with drains and seepage collection ditches. The field investigation focussed on the downgradient end of the tailings pond and dyke system, and groundwater flow and adjective transport modelling was used to support the analysis. Hydraulic measurements and water samples were taken via a network of piezometers and drive points to characterize the flow system of surface and ground water. Chemical tracers indicate that PAW had migrated to a shallow, permeable sand deposit on the other side of the inner seepage collection ditch and that further migration was prevented by elevated hydraulic heads on the other side of the outer ditch. A groundwater flow model was developed to simulate the hydraulic dyke conditions and estimate the amount of PAW discharging into the shallow aquifer. PAW has different chemical concentrations and stable isotope characteristics than groundwater; the parameters set forth in the study can be used to effectively track PAW migration in the future. It was concluded that the seepage collection system is adequate for effectively containing PAW under present hydraulic conditions. 25 refs., 3 tabs., 8 figs.

  17. Defect accumulation under cascade damage conditions

    DEFF Research Database (Denmark)

    Trinkaus, H.; Singh, B.N.; Woo, C.H.

    1994-01-01

    discussed in terms of this reaction kinetics taking into account cluster production, dissociation, migration and annihilation at extended sinks. Microstructural features which are characteristic of cascade damage and cannot be explained in terms of the conventional single defect reaction kinetics are...

  18. Cascaded frequency doublers for broadband laser radiation

    Energy Technology Data Exchange (ETDEWEB)

    Andreev, N F; Vlasova, K V; Davydov, V S; Kulikov, S M; Makarov, A I; Sukharev, Stanislav A; Freidman, Gennadii I; Shubin, S V

    2012-10-31

    A new scheme of a cascaded converter of the first harmonic of broadband cw laser radiation into the second harmonic (SH) with compensation for the group walk-off in cascades is proposed and investigated. The conditions under which high conversion coefficients of broadband ({approx}33 cm{sup -1}) single-mode fibre laser radiation with low peak power ({approx}300 W) into the SH are determined for frequency doublers based on the most promising LBO crystal. Conversion of cw radiation with an average power of 300 W and efficiency {eta} = 4.5 % into the SH is obtained in a single LBO crystal. Effect of coherent addition of SH radiation excited in different cascades is demonstrated for two- and three-stage schemes. The expected conversion efficiencies, calculated disregarding loss but taking into account real aberrations of elements, are 18 % and 38 %, respectively. The effect of pumping depletion begins to manifest itself in the third cascade of a three-stage converter; it may reduce the latter value to {approx}30 %. (nonlinear optical phenomena)

  19. Cascaded frequency doublers for broadband laser radiation

    Science.gov (United States)

    Andreev, N. F.; Vlasova, K. V.; Davydov, V. S.; Kulikov, S. M.; Makarov, A. I.; Sukharev, Stanislav A.; Freidman, Gennadii I.; Shubin, S. V.

    2012-10-01

    A new scheme of a cascaded converter of the first harmonic of broadband cw laser radiation into the second harmonic (SH) with compensation for the group walk-off in cascades is proposed and investigated. The conditions under which high conversion coefficients of broadband (~33 cm-1) single-mode fibre laser radiation with low peak power (~300 W) into the SH are determined for frequency doublers based on the most promising LBO crystal. Conversion of cw radiation with an average power of 300 W and efficiency η = 4.5 % into the SH is obtained in a single LBO crystal. Effect of coherent addition of SH radiation excited in different cascades is demonstrated for two- and three-stage schemes. The expected conversion efficiencies, calculated disregarding loss but taking into account real aberrations of elements, are 18 % and 38 %, respectively. The effect of pumping depletion begins to manifest itself in the third cascade of a three-stage converter; it may reduce the latter value to ~30 %.

  20. Modeling and simulation of cascading contingencies

    Science.gov (United States)

    Zhang, Jianfeng

    This dissertation proposes a new approach to model and study cascading contingencies in large power systems. The most important contribution of the work involves the development and validation of a heuristic analytic model to assess the likelihood of cascading contingencies, and the development and validation of a uniform search strategy. We model the probability of cascading contingencies as a function of power flow and power flow changes. Utilizing logistic regression, the proposed model is calibrated using real industry data. This dissertation analyzes random search strategies for Monte Carlo simulations and proposes a new uniform search strategy based on the Metropolis-Hastings Algorithm. The proposed search strategy is capable of selecting the most significant cascading contingencies, and it is capable of constructing an unbiased estimator to provide a measure of system security. This dissertation makes it possible to reasonably quantify system security and justify security operations when economic concerns conflict with reliability concerns in the new competitive power market environment. It can also provide guidance to system operators about actions that may be taken to reduce the risk of major system blackouts. Various applications can be developed to take advantage of the quantitative security measures provided in this dissertation.

  1. Gain and Loss in Quantum Cascade Lasers

    OpenAIRE

    Wacker, A.; Lee, S. -C.

    2001-01-01

    We report gain calculations for a quantum cascade laser using a fully self-consistent quantum mechanical approach based on the theory of nonequilibrium Green functions. Both the absolute value of the gain as well as the spectral position at threshold are in excellent agreement with experimental findings for T=77 K. The gain strongly decreases with temperature.

  2. Electrically Tunable Terahertz Quantum-Cascade Lasers

    Science.gov (United States)

    Gunapala, Sarath; Soidel, Alexander; Mansour, Kamjou

    2006-01-01

    Improved quantum-cascade lasers (QCLs) are being developed as electrically tunable sources of radiation in the far infrared spectral region, especially in the frequency range of 2 to 5 THz. The structures of QCLs and the processes used to fabricate them have much in common with those of multiple- quantum-well infrared photodetectors.

  3. Quantum Cascade Lasers in Biomedical Infrared Imaging.

    Science.gov (United States)

    Bird, Benjamin; Baker, Matthew J

    2015-10-01

    Technological advances, namely the integration of quantum cascade lasers (QCLs) within an infrared (IR) microscope, are enabling the development of valuable label-free biomedical-imaging tools capable of targeting and detecting salient chemical species within practical clinical timeframes. PMID:26409774

  4. Monolithic photonic crystal quantum-cascade laser

    Energy Technology Data Exchange (ETDEWEB)

    Benz, A; Deutsch, C H; Fasching, G; Unterrainer, K [Photonics Institute and Center for Micro- and Nanostructures, Vienna University of Technology, Gusshausstrasse 29/387, A-1040 Vienna (Austria); Andrews, A M; Klang, P; Schrenk, W; Strasser, G, E-mail: alexander.benz@tuwien.ac.a [Institute of Solid-State Electronics and Center for Micro- and Nanostructures, Vienna University of Technology, Floragasse 7/362, A-1040 Vienna (Austria)

    2009-11-15

    We present the design and realization of active photonic crystal (PhC) terahertz quantum-cascade lasers. The devices consist of sub-wavelength isolated pillars which are embedded in a double-metal waveguide. The lasing is observed at flat-band regions not in the bandgap itself. A stable single-mode emission under all driving conditions is achieved.

  5. Geothermal research, Oregon Cascades: Final technical report

    Energy Technology Data Exchange (ETDEWEB)

    Priest, G.R.; Black, G.L.

    1988-10-27

    Previous USDOE-funded geothermal studies have produced an extensive temperature gradient and heat flow data base for the State of Oregon. One of the important features identified as a result of these studies is a rapid transition from heat flow values on the order of 40 mW/m/sup 2/ in the Willamette Valley and Western Cascades to values of greater than or equal to100 mW/m/sup 2/ in the High Cascades and the eastern portion of the Western Cascades. These data indicate that the Cascade Range in Oregon has potential as a major geothermal province and stimulated much of the later work completed by government agencies and private industry. Additional data generated as a result of this grant and published in DOGAMI Open-File Report 0-86-2 further define the location and magnitude of this transition zone. In addition, abundant data collected from the vicinity of Breitenbush and Austin Hot Springs have permitted the formulation of relatively detailed models of these hydrothermal systems. These models are published in DOGAMI Open-File Report 0-88-5. Task 1.2 of the Deliverables section of Amendment M001 is fulfilled by DOGAMI publication GMS-48, Geologic map of the McKenzie Bridge quadrangle, Lane County, Oregon. This map was printed in October, 1988, and is part of the final submission to USDOE. 8 refs.

  6. Population analysis for atomic cascade decay processes

    International Nuclear Information System (INIS)

    Down-stream cascade decay processes in atomic systems are analyzed by solving a coupled rate equation for which an analytical solution for a population in each excited state is obtained. Some typical numerical examples for populations to interpret the decay passes connecting to features of optical or electron spectra observed in various collision experiments are also given. (author)

  7. Cascading effects of overfishing marine systems

    NARCIS (Netherlands)

    Scheffer, M.; Carpenter, S.; Young, de B.

    2005-01-01

    Profound indirect ecosystem effects of overfishing have been shown for coastal systems such as coral reefs and kelp forests. A new study from the ecosystem off the Canadian east coast now reveals that the elimination of large predatory fish can also cause marked cascading effects on the pelagic food

  8. Forecasting Social Unrest Using Activity Cascades.

    Directory of Open Access Journals (Sweden)

    Jose Cadena

    Full Text Available Social unrest is endemic in many societies, and recent news has drawn attention to happenings in Latin America, the Middle East, and Eastern Europe. Civilian populations mobilize, sometimes spontaneously and sometimes in an organized manner, to raise awareness of key issues or to demand changes in governing or other organizational structures. It is of key interest to social scientists and policy makers to forecast civil unrest using indicators observed on media such as Twitter, news, and blogs. We present an event forecasting model using a notion of activity cascades in Twitter (proposed by Gonzalez-Bailon et al., 2011 to predict the occurrence of protests in three countries of Latin America: Brazil, Mexico, and Venezuela. The basic assumption is that the emergence of a suitably detected activity cascade is a precursor or a surrogate to a real protest event that will happen "on the ground." Our model supports the theoretical characterization of large cascades using spectral properties and uses properties of detected cascades to forecast events. Experimental results on many datasets, including the recent June 2013 protests in Brazil, demonstrate the effectiveness of our approach.

  9. Forecasting Social Unrest Using Activity Cascades.

    Science.gov (United States)

    Cadena, Jose; Korkmaz, Gizem; Kuhlman, Chris J; Marathe, Achla; Ramakrishnan, Naren; Vullikanti, Anil

    2015-01-01

    Social unrest is endemic in many societies, and recent news has drawn attention to happenings in Latin America, the Middle East, and Eastern Europe. Civilian populations mobilize, sometimes spontaneously and sometimes in an organized manner, to raise awareness of key issues or to demand changes in governing or other organizational structures. It is of key interest to social scientists and policy makers to forecast civil unrest using indicators observed on media such as Twitter, news, and blogs. We present an event forecasting model using a notion of activity cascades in Twitter (proposed by Gonzalez-Bailon et al., 2011) to predict the occurrence of protests in three countries of Latin America: Brazil, Mexico, and Venezuela. The basic assumption is that the emergence of a suitably detected activity cascade is a precursor or a surrogate to a real protest event that will happen "on the ground." Our model supports the theoretical characterization of large cascades using spectral properties and uses properties of detected cascades to forecast events. Experimental results on many datasets, including the recent June 2013 protests in Brazil, demonstrate the effectiveness of our approach. PMID:26091012

  10. Conception and essential parameters of Lower Vistula river cascade

    International Nuclear Information System (INIS)

    General factors stimulated construction of the Lower Vistula river cascade are presented. Present state of the utilizing of river energy potential in Poland and experience of operation of Wloclawek water complex are briefly characterized. General technical parameters of the cascade are presented and the cascade is compared with chosen ones in Europe. Assessment of the cascade general economic parameters is conducted and end conclusions are formulated. (author). 14 refs, 1 fig., 2 tabs

  11. Cascades with coupled map lattices in preferential attachment community networks

    Institute of Scientific and Technical Information of China (English)

    Cui Di; Gao Zi-You; Zhao Xiao-Mei

    2008-01-01

    In this paper,cascading failure is studied by coupled map lattice (CML) methods in preferential attachment community networks.It is found that external perturbation R is increasing with modularity Q growing by simulation.In particular,the large modularity Q can hold off the cascading failure dynamic process in community networks.Furthermore,different attack strategies also greatly affect the cascading failure dynamic process. It is particularly significant to control cascading failure process in real community networks.

  12. A case study for biogas generation from covered anaerobic ponds treating abattoir wastewater: Investigation of pond performance and potential biogas production

    International Nuclear Information System (INIS)

    Highlights: • We report on the performance of a novel covered anaerobic pond system. • Potential biogas production was estimated using BioWin modelling software. • Ponds maintained stable operation; however, accumulation of crust was an issue. • Modelling indicated that biogas yield can be influenced by decomposition efficiency. • Configuration and operation of ponds can also impact potential biogas production. - Abstract: Covered anaerobic ponds offer significant advantages to the red meat processing industry by capturing methane rich gas as a fuel source for bioenergy while reducing greenhouse gas emissions (GHG). This paper presents the results of a novel-designed anaerobic pond system at an Australian abattoir in relation to pond performance and potential biogas production. Key findings in assessing the effectiveness of the system revealed that the covered ponds are capable of efficient wastewater decomposition and biogas production. The primary issue with the covered ponds at the abattoir was the build-up of fat/crust that prevented the accurate measurement of biogas and effective use of the cover. In the absence of field biogas data the novel application of the computer modelling software BioWin® was carried out to simulate chemical oxygen demand (COD) removal rates and subsequent biogas yield. The unique parameter used to fit field data was the fraction of the inlet COD due to a superficial crust which did not follow anaerobic digestion. Field data effluent COD removal rates were matched to simulated rates predicted by BioWin when measured influent COD was reduced to 30%. Biogas modelling results suggest significant variation in the economic benefit of biogas energy, with the quantity of biogas potentially varying tenfold (from 328 m3/d to 3284 m3/d) depending on site factors such as pond efficiency, pond configuration and operational practices

  13. 226Ra and 228Ra activities associated with agricultural drainage ponds and wetland ponds in the Kankakee Watershed, Illinois-Indiana, USA

    International Nuclear Information System (INIS)

    Background radioactivity is elevated in many agricultural drainage ponds and also constructed wetland ponds in the Kankakee watershed. During 1995-1999, gross-α and -β activities were measured up to 455 and 1650 mBq L-1, respectively. 226Ra and 228Ra averaged 139 and 192 mBq L-1 in controlled drainage ponds compared to 53 and 58 mBq L-1 for 226Ra and 228Ra, respectively, in native wetland ponds. Analyses of applied ammonium phosphate fertilizers near both native and controlled ponds indicate comparable 226Ra/228Ra and 228Ra/232Th activity ratios with only the surface waters in the controlled ponds. For example, 226Ra/ 228Ra activity ratios in controlled ponds ranged from 0.79 to 0.91 and group with a local fertilizer batch containing FL phosphate compounds with 226Ra/228Ra activity ratios of 0.83-1.04. Local soils of the Kankakee watershed have 226Ra/228Ra activity ratios of 0.54-0.70. Calculated Ra fluxes of waters, in drainage ditches associated with these controlled ponds, for 226Ra ranged from 0.77 to 9.00 mBq cm-2 d-1 and for 228Ra ranged from 1.22 to 8.43 mBq cm-2 d-1. Ra activity gradients were measured beneath these controlled ponds both in agricultural landscapes and in constructed wetlands, all being associated with drainage ditches. Ra had infiltrated to the local water table but was below regulatory maximum contaminant limits. Still, measurable Ra activity was measured downgradient of even the constructed wetlands in the Kankakee watershed, suggesting that the attenuation of Ra was low. However, no Ra excess was observed in the riparian zone or the Kankakee River downgradient of the native wetland ponds

  14. Cascade theory for isothermal atmosphere, 1

    International Nuclear Information System (INIS)

    A cascade shower formed by the gamma-ray produced at the depth of tsub(o)(c. u) in isothermal atmosphere was calculated by approx. A, Landau, and its result is reported. The electromagnetic cascade theory in the atmosphere is necessary in order to obtain the lateral structure of electromagnetic components in EAS calculation, and the result in case of uniform substance has been utilized. Further, effects of the generating point tsub(o) of gamma ray of EAS must be learned as it is not emitted at the top of atmosphere. Therefore, the calculation of the cascade in atmosphere has been performed. in the case that the energy spectra of incident photons are Esub(o)sup(-γ-1) dEsub(o) is plotted, when γ is 1.0, 1.5, and 2.0. As tsub(o) becomes larger, it conforms to the case of uniform substance; whereas when tsub(o) is o, the difference from unifrom substance is maximum. The result of calculation by saddle point approximation was compared with Misaki's result in the case of uniform substance. The difference from unifrom substance is about twice as compared by the Moliere unit at the observed point. If the Moliere unit over several cascade units is used, good approximation can be obtained as Kamata-Nishimura have pointed out. Further, it is shown that over how much cascade units the Moliere unit used must be taken so that E)sup(2)>is in conformity, when tsub(o) is o, and Esub(o)/E is 104. Numerical calculation of f(a1, a2, t, tsub(o)) is appended. (Iwakiri, K.)

  15. Geohydrology of the Flints Pond Aquifer, Hollis, New Hampshire

    Science.gov (United States)

    Ayotte, Joseph D.; Dorgan, Tracy H.

    1995-01-01

    Flints pond has been subjected to accelerated eutrophication as a result of watershed development (building of new homes and conversion of summer cottages into permanent homes) since the 1930's. Ground-water flow is the primary recharge and discharge mechanism for Flints Pond. The saturated thickness, transmissive properties, and altitude of the water table were determined by use of surface geophysics, test drilling, and aquifer-test data. Information on the geohydrology of the adjacent Flints Pond aquifer can be used in developing a water and nutrient budget for the pond-aquifer system. Ground-penetrating-radar surveys were done over more than 4 miles of the study area and on Flints Pond. Three distinct reflection signatures were commonly identifiable on the radar profiles: (1) thin, relatively flat-lying, continuous reflectors that represent fine-grained lacustrine sediment; (2) subparallel to hummocky and chaotic, coarse-grained reflectors that possibly represent coarse-grained ice-contact deposits or deltaic sediments in a lacustrine environment; and (3) sharply diffracted, fine-grained, chaotic reflectors that represent till and (or) till over bedrock. The saturated thickness of the aquifer exceeds 90 feet in the northern end of the study area and averages 30 to 50 feet in the southern and eastern parts. The saturated thickness of the western part is generally less than 10 feet. Test borings were completed at 19 sites and 13 wells (6 of which were nested pairs) were installed in various lithologic units. A water-table map, constructed from data collected in November 1994, represents average water-table conditions in the aquifer. Horizontal hydraulic conductivities calculated from single-well aquifer test data for stratified drift range from 2.8 to 226 feet per day. Hydraulic conductivities were quantitatively correlated with the reflector signatures produced with ground-penetrating radar so that transmissivities could be inferred for areas where well data were

  16. Albedo of photons in high energy electromagnetic and hadronic cascades

    International Nuclear Information System (INIS)

    The albedo of photons in electromagnetic cascades is simulated. A simple model of back current photons generation and propagation in electromagnetic cascades is considered which satisfactorily describes the general features of albedo behavior. The contribution to the photonic albedo of electromagnetic subshowers generated by high energy gamma-quanta from π0 decays in the hadron initiated cascade is evaluated. (orig.)

  17. Convergence Analysis of a Cascade Architecture Neural Network

    Science.gov (United States)

    Duong, Tuan A.; Stubberub, Allen R.; Daud, Taher; Thakoor, Anil

    1997-01-01

    In this paper, we present a mathematical foundation, including a convergence analysis, for cascading architecture neural networks. From this, a mathematical foundation for the casade correlation learning algorithm can also be found. Furthermore, it becomes apparent that the cascade correlation scheme is a special case of an efficient hardware learning algorithm called Cascade Error Projection.

  18. Z-Scan Characteristics of Cascading Nonlinear Media

    Institute of Scientific and Technical Information of China (English)

    臧维平; 田建国; 刘智波; 周文远; 杨新江; 张春平; 张光寅

    2003-01-01

    We present a method, which combines the Gaussian decomposition method and the "distributed-lens" method,for analysing Z-scan curves of cascading nonlinear medium layers or a complicated cascading structure. A good agreement with the experimental data is obtained. The method would be useful to design optical limiters and to determine the nonlinearities of cascading medium layers.

  19. Benthic microbial communities of coastal terrestrial and ice shelf Antarctic meltwater ponds

    OpenAIRE

    Archer, Stephen D. J.; McDonald, Ian R.; Herbold, Craig W.; Lee, Charles K; Cary, Craig S.

    2015-01-01

    The numerous perennial meltwater ponds distributed throughout Antarctica represent diverse and productive ecosystems central to the ecological functioning of the surrounding ultra oligotrophic environment. The dominant taxa in the pond benthic communities have been well described however, little is known regarding their regional dispersal and local drivers to community structure. The benthic microbial communities of 12 meltwater ponds in the McMurdo Sound of Antarctica were investigated to ex...

  20. Performance of a Laboratory-scale Microalgae Pond for Secondary Treatment of Distillery Wastewaters

    OpenAIRE

    Travieso, L.; Benítez, F.; Sánchez, E.; Borja, R.; De León, M; Raposo, F.; Rincón, B.

    2008-01-01

    Distillery waste disposal is one of the major problems being faced by all nations across the globe. To diminish its organic loading, the distillery waste is treated before its final disposal by biological processes. Microalgae pond gives a way to solve this situation. An evaluation of the performance of a laboratory-scale microalgae pond treating distillery waste previously treated in an anaerobic filter was carried out. The microalgae pond operated with an effluent recycling (R) of 10:1 w...

  1. Little Fish in a Big Pond--Time to Get Schooled!

    Science.gov (United States)

    Moye, Johnny J.

    2011-01-01

    One technique used by many who fish is to catch a fish in a creek or pond and then release it in a different pond. This satisfies the desire for sport, and it also serves to stock a pond that may need replenishment. Of course this restocking can be a traumatic experience for the new fish. To survive in the new environment, the fish must find its…

  2. A Simple Heat and Mass Transfer Model for Salt Gradient Solar Ponds

    OpenAIRE

    Safwan Kanan, Jonathan Dewsbury, Gregory Lane-Serff

    2014-01-01

    Abstract—A salinity gradient solar pond is a free energy source system for collecting, converting and storing solar energy as heat. In this paper, the principles of solar pond are explained. A mathematical model is developed to describe and simulate heat and mass transfer behavior of salinity gradient solar pond. MATLAB codes are programmed to solve the one dimensional finite difference method for heat and mass transfer equations. Temperature profiles and concentration distributions are calcu...

  3. Assessing metal pollution in ponds constructed for controlling runoff from reclaimed coal mines

    OpenAIRE

    Miguel Chinchilla, Leticia; Gónzalez, Eduardo; Comín, Francisco A.

    2014-01-01

    Constructing ponds to protect downstream ecosystems is a common practice in opencast coal mine reclamation. As these ponds remain integrated in the landscape, it is important to evaluate the extent of the effect of mine pollution on these ecosystems. However, this point has not been sufficiently addressed in the literature. The main objective of this work was to explore the metal pollution in man-made ponds constructed for runoff control in reclaimed opencast coal mines over time. To do so, w...

  4. A Lipid-Accumulating Alga Maintains Growth in Outdoor, Alkaliphilic Raceway Pond with Mixed Microbial Communities

    OpenAIRE

    Bell, Tisza A. S.; Prithiviraj, Bharath; Wahlen, Brad D.; Matthew W Fields; Peyton, Brent M.

    2016-01-01

    Algal biofuels and valuable co-products are being produced in both open and closed cultivation systems. Growing algae in open pond systems may be a more economical alternative, but this approach allows environmental microorganisms to colonize the pond and potentially infect or outcompete the algal “crop.” In this study, we monitored the microbial community of an outdoor, open raceway pond inoculated with a high lipid-producing alkaliphilic alga, Chlorella vulgaris BA050. The strain C. vulgari...

  5. Distribution and Diversity of Oligochaetes in Selected Ponds of Thiruvananthapuram District, Kerala, South India

    OpenAIRE

    Ragi, M. S.; Jaya, D. S.

    2014-01-01

    The present study was carried out to evaluate the distribution and diversity of oligochaete fauna in selected ponds of Thiruvananthapuram district in Kerala, South India. The sediment samples were collected from three ponds seasonally during the period December 2006 to November 2008. In the study, 10 oligochaete species which belong to 8 genera were identified in three selected ponds. These include Dero digitata, Dero nivea, Dero obtusa, Pristina longiseta, Aulophorus furcatus, Stylaria fossu...

  6. Can Environmental Education Actions Change Public Attitudes? An Example Using the Pond Habitat and Associated Biodiversity

    OpenAIRE

    Sousa, Eunice; Quintino, Victor; Palhas, Jael; Rodrigues, Ana Maria; Teixeira, José

    2016-01-01

    Ponds provide vital ecological services. They are biodiversity hotspots and important breading sites for rare and endangered species, including amphibians and dragonflies. Nevertheless, their number is decreasing due to habitat degradation caused by human activities. The “Ponds with Life” environmental education project was developed to raise public awareness and engagement in the study of ponds by promoting the direct contact between the public and nature, researchers and pedagogical hands-o...

  7. When is the best time to sample aquatic macroinvertebrates in ponds for biodiversity assessment?

    OpenAIRE

    Hill, M. J.; Sayer, C. D.; Wood, P J

    2016-01-01

    Ponds are sites of high biodiversity and conservation value, yet there is little or no statutory monitoring of them across most of Europe. There are clear and standardised protocols for sampling aquatic macroinvertebrate communities in ponds, but the most suitable time(s) to undertake the survey(s) remains poorly specified. This paper examined the aquatic macroinvertebrate communities from 95 ponds within different land use types over three seasons (spring, summer and autumn) to determine the...

  8. COLONIZATION OF MANGROVE FOREST AT ABANDONED SHRIMP-POND OF SEGARA ANAKAN-CILACAP

    OpenAIRE

    Tjut Sugandawaty Djohan

    2015-01-01

    During the 1996 to 1997, large areas of mangrove forest in the Segara Anakan were cleared and converted into intensive shrimp-ponds. After one to two years, these shrimp-ponds failed and were abandoned. These abandoned ponds created large gap areas and canopy gaps, which were colonized by mangrove shrub and liana. The Segara Anakan mangrove also experienced heavy siltation, and there were tree cuttings from the remnant of the mangrove trees. This research aimed to study the colonization of ma...

  9. Don Quixote Pond: A Small Scale Model of Weathering and Salt Accumulation

    Science.gov (United States)

    Englert, P.; Bishop, J. L.; Patel, S. N.; Gibson, E. K.; Koeberl, C.

    2015-01-01

    The formation of Don Quixote Pond in the North Fork of Wright Valley, Antarctica, is a model for unique terrestrial calcium, chlorine, and sulfate weathering, accumulation, and distribution processes. The formation of Don Quixote Pond by simple shallow and deep groundwater contrasts more complex models for Don Juan Pond in the South Fork of Wright Valley. Our study intends to understand the formation of Don Quixote Pond as unique terrestrial processes and as a model for Ca, C1, and S weathering and distribution on Mars.

  10. Description of work for 216-U-Pond cone penetrometer demonstration

    International Nuclear Information System (INIS)

    This description of work details the Proposed field activities associated with Cone Penetrometer (CPT) work at the 216-U-10 Pond (U-10 Pond) in the 200 West Area and will serve as a field guide for those performing the work. The U-10 Pond was constructed in 1944 to receive low-level liquid effluent from the various chemical reprocessing facilities within the 200 West Area. The U-10 Pond covered 30 acres and received approximately 4.3 x 1010 gal of contaminated liquid. Sampling conducted in 1980 indicated that the most significant radionuclides were 90Sr, 137Cs, plutonium, and uranium (DOE-RL 1993). The pond was deactivated and stabilized in 1985 with clean fill dirt. The thickness of the stabilization cover is variable across the former pond and ranges between 2 ft near the pond margins and delta area to 8 feet in the deepest section of the pond. The purpose of this work is to establish the extent of contamination beneath the U-10 pond

  11. Northern Seasonal Woodland Ponds: Distribution, Biota, and Ecological Linkages with the Surrounding Forest

    Science.gov (United States)

    Batzer, D.; Palik, B.

    2005-05-01

    Seasonal woodland ponds are important landscape features across much of eastern and central North America. Learning more about the ecology of these habitats is a pressing need in the US because federal protections are being reduced. Further, the fates of these habitats are not being monitored because most are too small for inclusion in the National Wetland Inventory. In our northern Minnesota study area, the distribution of seasonal woodland ponds is strongly influenced by glacial landform, with most ponds being associated with ground or end moraines. The habitats support an abundance of plants, invertebrates, and amphibians; these organisms are well adapted for the variable environments existing in ponds and they posses a durability that makes them resistant to most natural variation in conditions. Because of the small size of seasonal woodland ponds, input of plant litter and migration of invertebrates from the surrounding forest into ponds is an important ecological link. However, because ponds support an autochthonous growth of wetland trees, the relationship between ponds and the forest differs from that between streams and forests. Like eastern streams, logging of forests around ponds is a concern, but impacts of peripheral logging on theses wetlands appear less dramatic than for streams.

  12. High energy electromagnetic cascades in extragalactic space: physics and features

    CERN Document Server

    Berezinsky, V

    2016-01-01

    Using the analytic modeling of the electromagnetic cascades compared with more precise numerical simulations we describe the physical properties of electromagnetic cascades developing in the universe on CMB and EBL background radiations. A cascade is initiated by very high energy photon or electron and the remnant photons at large distance have two-component energy spectrum, $\\propto E^{-2}$ ($\\propto E^{-1.9}$ in numerical simulations) produced at cascade multiplication stage, and $\\propto E^{-3/2}$ from Inverse Compton electron cooling at low energies. The most noticeable property of the cascade spectrum in analytic modeling is 'strong universality', which includes the standard energy spectrum and the energy density of the cascade $\\omega_{\\rm cas}$ as its only numerical parameter. Using numerical simulations of the cascade spectrum and comparing it with recent Fermi LAT spectrum we obtained the upper limit on $\\omega_{\\rm cas}$ stronger than in previous works. The new feature of the analysis is "$E_{\\max}$...

  13. Cascade Apartments: Deep Energy Multifamily Retrofit

    Energy Technology Data Exchange (ETDEWEB)

    Gordon, A.; Mattheis, L.; Kunkle, R.; Howard, L.; Lubliner, M.

    2014-02-01

    In December of 2009-10, King County Housing Authority (KCHA) implemented energy retrofit improvements in the Cascade multifamily community, located in Kent, Washington (marine climate.)This research effort involved significant coordination from stakeholders KCHA, WA State Department of Commerce, utility Puget Sound Energy, and Cascade tenants. This report focuses on the following three primary BA research questions : 1. What are the modeled energy savings using DOE low income weatherization approved TREAT software? 2. How did the modeled energy savings compare with measured energy savings from aggregate utility billing analysis? 3. What is the Savings to Investment Ratio (SIR) of the retrofit package after considering utility window incentives and KCHA capitol improvement funding.

  14. Single mode terahertz quantum cascade amplifier

    Energy Technology Data Exchange (ETDEWEB)

    Ren, Y., E-mail: yr235@cam.ac.uk; Wallis, R.; Shah, Y. D.; Jessop, D. S.; Degl' Innocenti, R.; Klimont, A.; Kamboj, V.; Beere, H. E.; Ritchie, D. A. [Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, CB3 0HE Cambridge (United Kingdom)

    2014-10-06

    A terahertz (THz) optical amplifier based on a 2.9 THz quantum cascade laser (QCL) structure has been demonstrated. By depositing an antireflective coating on the QCL facet, the laser mirror losses are enhanced to fully suppress the lasing action, creating a THz quantum cascade (QC) amplifier. Terahertz radiation amplification has been obtained, by coupling a separate multi-mode THz QCL of the same active region design to the QC amplifier. A bare cavity gain is achieved and shows excellent agreement with the lasing spectrum from the original QCL without the antireflective coating. Furthermore, a maximum optical gain of ∼30 dB with single-mode radiation output is demonstrated.

  15. Cascade Apartments: Deep Energy Multifamily Retrofit

    Energy Technology Data Exchange (ETDEWEB)

    Gordon, A. [Washington State Univ. Energy Program, Olympia, WA (United States); Mattheis, L. [Washington State Univ. Energy Program, Olympia, WA (United States); Kunkle, R. [Washington State Univ. Energy Program, Olympia, WA (United States); Howard, L. [Washington State Univ. Energy Program, Olympia, WA (United States); Lubliner, M. [Washington State Univ. Energy Program, Olympia, WA (United States)

    2014-02-01

    In December of 2009-10, King County Housing Authority (KCHA) implemented energy retrofit improvements in the Cascade multifamily community, located in Kent, Washington (marine climate.)This research effort involved significant coordination from stakeholders KCHA, WA State Department of Commerce, utility Puget Sound Energy, and Cascade tenants. This report focuses on the following three primary BA research questions: 1. What are the modeled energy savings using DOE low income weatherization approved TREAT software? 2. How did the modeled energy savings compare with measured energy savings from aggregate utility billing analysis? 3. What is the Savings to Investment Ratio (SIR) of the retrofit package after considering utility window incentives and KCHA capitol improvement funding.

  16. Aspects of flow attenuation performance of retention ponds

    Science.gov (United States)

    Wallis, S. G.; Morgan, C. T.; Heal, K.

    2003-04-01

    The work reported here is part of a wider modelling study into the performance of sustainable urban drainage systems (SUDS) in Scotland. Developments that increase the urbanisation of catchments are now required by the Scottish Environment Protection Agency to include SUDS to protect receiving watercourses from flooding and water quality deterioration. Here we report specifically on some initial simulations of storm water retention ponds. These are normally wet storage facilities that provide both flow attenuation and water quality treatment (from settlement of suspended solids and biological treatment of some pollutants). Here we focus on the flow attenuation characteristics. A sensitivity analysis was performed on a model of a cylindrical pond with outflow through a V-notch weir. The aim of the simulations was to help us to learn about the flow attenuation characteristics of retention ponds, so that later work could be properly focused on the key issues. In addition the flow simulation model underpins later models of water quality and sedimentation, so it was important to ensure that its simulations were realistic. The inflows were constructed using an isosceles triangular inflow hydrograph with a peak flow of 50 l/s, a storm duration of 3.2 hours and a total inflow volume of 288 l. Values of four pond parameters were varied to test model sensitivity: radius, weir angle, weir crest elevation and initial water level. Sensitivity was investigated by observing the changes in several flow attenuation performance indicators. These were total outflow volume, peak outflow and the following three time delays: peak time delay (lag between peaks of outflow and inflow hydrographs), centroid time delay (lag between centroids of outflow and inflow hydrographs) and initial time delay (lag between the initial rise of the outflow and inflow hydrographs). Simulations were carried out using a simple Euler discretisation of the storage routing equation. A time step of 1.5 minutes

  17. Direct and inverse cascades in the geodynamo

    Czech Academy of Sciences Publication Activity Database

    Reshetnyak, M.; Hejda, Pavel

    2008-01-01

    Roč. 15, č. 6 (2008), s. 873-880. ISSN 1023-5809 R&D Projects: GA AV ČR IAA300120704 Institutional research plan: CEZ:AV0Z30120515 Keywords : geodynamo * forward and inverse cascades * magnetic field Subject RIV: DE - Earth Magnetism, Geodesy, Geography Impact factor: 1.022, year: 2008 www.nonlin-processes-geophys.net/15/873/2008/

  18. Impact of Community Structure on Cascades

    OpenAIRE

    Moharrami, Mehrdad; Subramanian, Vijay; Liu, Mingyan; Lelarge, Marc

    2016-01-01

    The threshold model is widely used to study the propagation of opinions and technologies in social networks. In this model individuals adopt the new behavior based on how many neighbors have already chosen it. We study cascades under the threshold model on sparse random graphs with community structure to see whether the existence of communities affects the number of individuals who finally adopt the new behavior. Specifically, we consider the permanent adoption model where nodes that have ado...

  19. LOSS COEFFICIENT DEPENDENCE OF TURBINE BLADE CASCADE

    Czech Academy of Sciences Publication Activity Database

    Matějka, M.; Šafařík, P.; Luxa, Martin; Šimurda, David; Synáč, J.

    Glasgow: ASME, 2010, s. 1-9. ISBN 978-0-7918-4402-1. [ASME Turbo Expo 2010. Glasgow (GB), 14.06.2010-18.06.2010] R&D Projects: GA MŠk(CZ) 1M06031; GA AV ČR(CZ) IAA200760801 Institutional research plan: CEZ:AV0Z20760514 Keywords : loss coefficient * turbine cascade * pneumatic measurement Subject RIV: BK - Fluid Dynamics http://www.asmeconferences.org/TE10/ConfSpecInfo.cfm

  20. An asymmetric pericyclic cascade approach to oxindoles

    OpenAIRE

    Richmond, Edward

    2014-01-01

    The research in this thesis describes an asymmetric pericyclic cascade approach to the synthesis of a range of enantioenriched oxindoles using enantiopure oxazolidine derived nitrones and disubstituted ketenes. Chapter 1 aims to place this work in the context of the literature, describing other commonly employed or state-of-the-art asymmetric approaches to oxindoles and related compounds. Examples of where these approaches have been used successfully in the total synthesis of related indol...

  1. Modeling techniques for quantum cascade lasers

    Energy Technology Data Exchange (ETDEWEB)

    Jirauschek, Christian [Institute for Nanoelectronics, Technische Universität München, D-80333 Munich (Germany); Kubis, Tillmann [Network for Computational Nanotechnology, Purdue University, 207 S Martin Jischke Drive, West Lafayette, Indiana 47907 (United States)

    2014-03-15

    Quantum cascade lasers are unipolar semiconductor lasers covering a wide range of the infrared and terahertz spectrum. Lasing action is achieved by using optical intersubband transitions between quantized states in specifically designed multiple-quantum-well heterostructures. A systematic improvement of quantum cascade lasers with respect to operating temperature, efficiency, and spectral range requires detailed modeling of the underlying physical processes in these structures. Moreover, the quantum cascade laser constitutes a versatile model device for the development and improvement of simulation techniques in nano- and optoelectronics. This review provides a comprehensive survey and discussion of the modeling techniques used for the simulation of quantum cascade lasers. The main focus is on the modeling of carrier transport in the nanostructured gain medium, while the simulation of the optical cavity is covered at a more basic level. Specifically, the transfer matrix and finite difference methods for solving the one-dimensional Schrödinger equation and Schrödinger-Poisson system are discussed, providing the quantized states in the multiple-quantum-well active region. The modeling of the optical cavity is covered with a focus on basic waveguide resonator structures. Furthermore, various carrier transport simulation methods are discussed, ranging from basic empirical approaches to advanced self-consistent techniques. The methods include empirical rate equation and related Maxwell-Bloch equation approaches, self-consistent rate equation and ensemble Monte Carlo methods, as well as quantum transport approaches, in particular the density matrix and non-equilibrium Green's function formalism. The derived scattering rates and self-energies are generally valid for n-type devices based on one-dimensional quantum confinement, such as quantum well structures.

  2. Free carrier absorption in quantum cascade structures

    OpenAIRE

    Carosella, F.; Ndebeka-Bandou, C.; Ferreira, R.; Dupont, E; K. Unterrainer; Strasser, G.; Wacker, Andreas; Bastard, G.

    2011-01-01

    We show that the free carrier absorption in Quantum Cascade Lasers is very small and radically different from the classical Drude result on account of the orthogonality between the direction of the carrier free motion and the electric field of the laser emission. A quantum mechanical calculation of the free carrier absorption and inter-subband oblique absorption induced by interface defects, coulombic impurities and optical phonon absorption/emission is presented for QCL's with a double quant...

  3. Extraction-Controlled Quantum Cascade Lasers

    OpenAIRE

    Wacker, Andreas

    2010-01-01

    A simple two-well design for terahertz quantum cascade lasers is proposed which is based on scattering injection and the efficient extraction of electrons from the lower laser level by resonant tunneling. In contrast to existing designs this extraction also controls the positive differential conductivity. The device is analyzed by calculations based on nonequilibrium Green's functions, which predict lasing operation well above 200 K at a frequency of 2.8 THz. (C) 2010 American Institute o...

  4. Modeling techniques for quantum cascade lasers

    International Nuclear Information System (INIS)

    Quantum cascade lasers are unipolar semiconductor lasers covering a wide range of the infrared and terahertz spectrum. Lasing action is achieved by using optical intersubband transitions between quantized states in specifically designed multiple-quantum-well heterostructures. A systematic improvement of quantum cascade lasers with respect to operating temperature, efficiency, and spectral range requires detailed modeling of the underlying physical processes in these structures. Moreover, the quantum cascade laser constitutes a versatile model device for the development and improvement of simulation techniques in nano- and optoelectronics. This review provides a comprehensive survey and discussion of the modeling techniques used for the simulation of quantum cascade lasers. The main focus is on the modeling of carrier transport in the nanostructured gain medium, while the simulation of the optical cavity is covered at a more basic level. Specifically, the transfer matrix and finite difference methods for solving the one-dimensional Schrödinger equation and Schrödinger-Poisson system are discussed, providing the quantized states in the multiple-quantum-well active region. The modeling of the optical cavity is covered with a focus on basic waveguide resonator structures. Furthermore, various carrier transport simulation methods are discussed, ranging from basic empirical approaches to advanced self-consistent techniques. The methods include empirical rate equation and related Maxwell-Bloch equation approaches, self-consistent rate equation and ensemble Monte Carlo methods, as well as quantum transport approaches, in particular the density matrix and non-equilibrium Green's function formalism. The derived scattering rates and self-energies are generally valid for n-type devices based on one-dimensional quantum confinement, such as quantum well structures

  5. Absorption spectroscopy with quantum cascade lasers

    Science.gov (United States)

    Kosterev, A. A.; Curl, R. F.; Tittel, F. K.; Gmachl, C.; Capasso, F.; Sivco, D. L.; Baillargeon, J. N.; Hutchinson, A. L.; Cho, A. Y.

    2001-01-01

    Novel pulsed and cw quantum cascade distributed feedback (QC-DFB) lasers operating near lambda=8 micrometers were used for detection and quantification of trace gases in ambient air by means of sensitive absorption spectroscopy. N2O, 12CH4, 13CH4, and different isotopic species of H2O were detected. Also, a highly selective detection of ethanol vapor in air with a sensitivity of 125 parts per billion by volume (ppb) was demonstrated.

  6. Terahertz quantum cascade laser bandwidth prediction

    OpenAIRE

    Agnew, G; Grier, A; Taimre, T; Lim, YL; Ikonic, Z.; Dean, P.; Khanna, SP; Lachab, M.; Valavanis, A.; Cooper, JD; Harrison, P.; Linfield, EH; Davies, AG; D Indjin; Rakic, AD

    2015-01-01

    Recent research shows that terahertz quantum cascade lasers are well-suited to high speed free space communication. The results of both theoretical and laboratory work indicate the devices are able to deliver bandwidths in the gigahertz to tens of gigahertz range without the burden of relaxation oscillations found in diode lasers. Using a novel rate equation model we explore the frequency response characteristics of a real device and report on the finding of a strongly peaked bias current-dep...

  7. HIV treatment cascade in tuberculosis patients

    OpenAIRE

    Lessells, Richard J; Swaminathan, Soumya; Godfrey-Faussett, Peter

    2016-01-01

    Purpose of review Globally, the number of deaths associated with tuberculosis (TB) and HIV coinfection remains unacceptably high. We review the evidence around the impact of strengthening the HIV treatment cascade in TB patients and explore recent findings about how best to deliver integrated TB/HIV services. Recent findings There is clear evidence that the timely provision of antiretroviral therapy (ART) reduces mortality in TB/HIV coinfected adults. Despite this, globally in 2013, only arou...

  8. Optical encryption with cascaded fractional wavelet transforms

    Institute of Scientific and Technical Information of China (English)

    BAO Liang-hua; CHEN Lin-fei; ZHAO Dao-mu

    2006-01-01

    On the basis of fractional wavelet transform, we propose a new method called cascaded fractional wavelet transform to encrypt images. It has the virtues of fractional Fourier transform and wavelet transform. Fractional orders, standard focal lengths and scaling factors are its keys. Multistage fractional Fourier transforms can add the keys easily and strengthen information security. This method can also realize partial encryption just as wavelet transform and fractional wavelet transform. Optical realization of encryption and decryption is proposed. Computer simulations confirmed its possibility.

  9. Evolution of Vertebrate Phototransduction: Cascade Activation.

    Science.gov (United States)

    Lamb, Trevor D; Patel, Hardip; Chuah, Aaron; Natoli, Riccardo C; Davies, Wayne I L; Hart, Nathan S; Collin, Shaun P; Hunt, David M

    2016-08-01

    We applied high-throughput sequencing to eye tissue from several species of basal vertebrates (a hagfish, two species of lamprey, and five species of gnathostome fish), and we analyzed the mRNA sequences for the proteins underlying activation of the phototransduction cascade. The molecular phylogenies that we constructed from these sequences are consistent with the 2R WGD model of two rounds of whole genome duplication. Our analysis suggests that agnathans retain an additional representative (that has been lost in gnathostomes) in each of the gene families we studied; the evidence is strong for the G-protein α subunit (GNAT) and the cGMP phosphodiesterase (PDE6), and indicative for the cyclic nucleotide-gated channels (CNGA and CNGB). Two of the species (the hagfish Eptatretus cirrhatus and the lamprey Mordacia mordax) possess only a single class of photoreceptor, simplifying deductions about the composition of cascade protein isoforms utilized in their photoreceptors. For the other lamprey, Geotria australis, analysis of the ratios of transcript levels in downstream and upstream migrant animals permits tentative conclusions to be drawn about the isoforms used in four of the five spectral classes of photoreceptor. Overall, our results suggest that agnathan rod-like photoreceptors utilize the same GNAT1 as gnathostomes, together with a homodimeric PDE6 that may be agnathan-specific, whereas agnathan cone-like photoreceptors utilize a GNAT that may be agnathan-specific, together with the same PDE6C as gnathostomes. These findings help elucidate the evolution of the vertebrate phototransduction cascade from an ancestral chordate phototransduction cascade that existed prior to the vertebrate radiation. PMID:27189541

  10. Performance of an auto refrigerant cascade refrigerator operating in liquid refrigerant supply (LRS) mode with different cascade heat exchangers

    Science.gov (United States)

    Gurudath Nayak, H.; Venkatarathnam, G.

    2010-11-01

    Auto refrigerant cascade (ARC) refrigerators operating with zeotropic mixtures provide refrigeration at temperatures less than 173 K (-100 °C) using a single compressor. Different authors have suggested different cascade heat exchangers for ARC refrigerators. There is no study in literature that suggests at what temperature ranges one, two or three cascade heat exchangers are necessary. In this paper the performance of an ARC refrigerator operating in the liquid refrigerant supply mode and operating with optimized hydrocarbon mixtures and different cascade heat exchangers is studied. The optimum number of cascade heat exchangers (stages) to be used for different operating temperatures is suggested.

  11. BIOCIDE TREATMENT OF PONDS IN SCOTLAND TO ERADICATE SIGNAL CRAYFISH

    Directory of Open Access Journals (Sweden)

    PEAY S.

    2006-01-01

    Full Text Available This trial aimed to eradicate illegally introduced signal crayfish Pacifastacus leniusculus in the North Esk catchment, Scotland. Sites treated were (1 an isolated gravel-pit (c. 9,000 m3, with crayfish present for 6 years; (2 three dammed ponds, (c. 5,000 m3 and (3 a leaking, offline pond (c. 6,000 m3, with crayfish for two years. Preliminary toxicity tests with substrate present indicated doses. Treatment at sites (1 and (2 (in October 2004, water temperature 13°C comprised deoxygenation with sodium sulphite to stimulate emergence, then application of natural pyrethrum (Pyblast. Exposed margins were sprayed with Pyblast to prevent escapes. Crayfish mortality was high, but one survivor was seen after 5 days. Pyblast was applied from a tank with Na2SO3 residue, which subsequent investigation indicated reduced Pyblast below the target 0.1 mg l-1. Site (1 was re-treated (end October, target 0.15 mg l-1 Pyblast, no Na2SO3, 9°C. Mortality was confirmed using caged crayfish. Prior to treatment at site (2, throughflow was stopped and fish removed. Biomonitoring was carried out with freshwater shrimps Gammarus in the adjacent watercourse. Treatment of site (3 (December, target 0.2 mg l-1, 4°C necessitated continuous back-pumping of leakage for a 2-week recovery period to avoid contamination of the river downstream. Caged crayfish took up to 5 days for 100% mortality. No crayfish were found in a summer survey after the treatments with Pyblast alone, but were caught in the ponds with Na2SO3 pre-treatment. Monitoring is required for 2-5 years.

  12. Barn swallows nesting near radioactive leaching ponds in southeastern Idaho

    International Nuclear Information System (INIS)

    Seasonally occurring populations of barn swallows nest near the Test Reactor Area (TRA) radioactive leaching ponds on the Idaho National Engineering Laboratory (INEL) Site. These birds utilize leaching pond arthropods and are therefore capable of accumulating radioactive materials and exporting them from the INEL Site during migration. The breeding biology is discussed for these swallows and a control group located 100 km away. Total nestling mortality for the controls and a 1977 TRA population was found to be statistically identical. Over 20 fission and activation products have been detected in immature and adult TRA birds. Mean concentrations of detectable radionuclides were used to calculate internal dose rates, and results showed that Na-24 contributed about 72% of the total average of 21.9 mrad/d for adult birds. Concentration factors were also calculated for predominant radionuclides in swallows relative to filtered pond water. Data from LiF dosimeters in swallow nests constructed with contaminated mud indicated average dose rates were 84 mrad/d for eggs and 220 mrad/d for nestlings. Growth curves were constructed for the immature TRA birds and controls. The first clutch of TRA swallows was found to have a significantly lower mean growth rate constant than the first clutch of controls. The statistical difference in growth rate between the control and TRA first clutch populations may have resulted from differences in climate, nesting site habitat, or available food sources, and cannot be solely attributed to radiation exposure as a causative factor. Growth rate parameters for TRA birds were within the range of values reported in the literature

  13. Cascade laser applications: trends and challenges

    Science.gov (United States)

    d'Humières, B.; Margoto, Éric; Fazilleau, Yves

    2016-03-01

    When analyses need rapid measurements, cost effective monitoring and miniaturization, tunable semiconductor lasers can be very good sources. Indeed, applications like on-field environmental gas analysis or in-line industrial process control are becoming available thanks to the advantage of tunable semiconductor lasers. Advances in cascade lasers (CL) are revolutionizing Mid-IR spectroscopy with two alternatives: interband cascade lasers (ICL) in the 3-6μm spectrum and quantum cascade lasers (QCL), with more power from 3 to 300μm. The market is getting mature with strong players for driving applications like industry, environment, life science or transports. CL are not the only Mid-IR laser source. In fact, a strong competition is now taking place with other technologies like: OPO, VCSEL, Solid State lasers, Gas, SC Infrared or fiber lasers. In other words, CL have to conquer a share of the Mid-IR application market. Our study is a market analysis of CL technologies and their applications. It shows that improvements of components performance, along with the progress of infrared laser spectroscopy will drive the CL market growth. We compare CL technologies with other Mid-IR sources and estimate their share in each application market.

  14. Electrokinetic densification of coal fines in waste ponds

    International Nuclear Information System (INIS)

    The objective of this research is to apply electrokinetics to remove colloidal coal and mineral particles from coal washing ponds without the addition of chemical additives. Colloidal particles do not settle gravitationally, but because their surfaces are charged one can produce settling by applying an external electric field. Of specific interest is a lake near Centralia, Washington used to wash coal prior to combustion in an electrical power generation facility. Laboratory experiments have demonstrated that electrokinetic treatment is feasible, so this project is examining how to scale up laboratory results to an industrial level. Electrode configurations, power requirements, and system properties are being studied

  15. ELECTROKINETIC DENSIFICATION OF COAL FINES IN WASTE PONDS

    Energy Technology Data Exchange (ETDEWEB)

    E. James Davis

    1999-12-18

    The objective of this research was to demonstrate that electrokinetics can be used to remove colloidal coal and mineral particles from coal-washing ponds and lakes without the addition of chemical additives such as salts and polymeric flocculants. The specific objectives were: Design and develop a scaleable electrophoresis apparatus to clarify suspensions of colloidal coal and clay particles; Demonstrate the separation process using polluted waste water from the coal-washing facilities at the coal-fired power plants in Centralia, WA; Develop a mathematical model of the process to predict the rate of clarification and the suspension electrical properties needed for scale up.

  16. Wind Effects on Retention Time in Highway Ponds

    DEFF Research Database (Denmark)

    Bentzen, Thomas Ruby; Larsen, Torben; Rasmussen, Michael R.

    2008-01-01

    evaluate the quality of long term simulations based on historical rain series of the pollutant discharges from roads and highways. The idea of this paper is to evaluate the effects of wind on the retention time and compare the retention time for the situation of a spatial uniform wind shear stress with the...... situation of a "real" spatial non-uniform shear stress distribution on the surface of the pond. The result of this paper shows that wind plays a dominant role for the retention time and flow pattern. Furthermore, the results shows that the differences in retention time between the use of uniform and non...

  17. Metabolic acceleration in the pond snail Lymnaea stagnalis?

    Science.gov (United States)

    Zimmer, Elke I.; Ducrot, V.; Jager, T.; Koene, J.; Lagadic, L.; Kooijman, S. A. L. M.

    2014-11-01

    Under constant environmental conditions, most animals tend to grow following the von Bertalanffy growth curve. Deviations from this curve can point to changes in the environment that the animals experience, such as food limitation when the available food is not sufficient or suitable. However, such deviations can also point to a phenomenon called metabolic acceleration, which is receiving increasing attention in the field of Dynamic Energy Budget (DEB) modeling. Reasons for such an acceleration are usually changes in shape during ontogeny, which cause changes in the surface area to volume ratio of the organism. Those changes, in turn, lead to changes in some of the model parameters that have length in their dimension. The life-history consequences of metabolic acceleration as implemented in the DEB theory are an s-shaped growth curve (when body size is expressed as a length measure) and a prolongation of the hatching time. The great pond snail Lymnaea stagnalis was earlier found to be food limited during the juvenile phase in laboratory experiments conducted under classical ecotoxicity test protocols. The pond snail has isomorphic shell growth but yet does not exhibit the expected von Bertalanffy growth curve under food limitation. When applying the standard DEB model to data from such life-cycle experiments, we also found that the hatching time is consistently underestimated, which could be a sign of metabolic acceleration. We here present an application of the DEB model including metabolic acceleration to the great pond snail. We account for the simultaneous hermaphroditism of the snail by including a model extension that describes the relative investment into the male and female function. This model allowed us to adequately predict the life history of the snail over the entire life cycle. However, the pond snail does not change in shape substantially after birth, so the original explanation for the metabolic acceleration does not hold. Since the change in shape

  18. Methanotrophic bacteria in oilsands tailings ponds of northern Alberta

    OpenAIRE

    Saidi-Mehrabad, Alireza; He, Zhiguo; Tamas, Ivica; Sharp, Christine E; Brady, Allyson L.; Rochman, Fauziah F.; Bodrossy, Levente; Abell, Guy CJ; Penner, Tara; Dong, Xiaoli; Sensen, Christoph W.; Dunfield, Peter F.

    2012-01-01

    We investigated methanotrophic bacteria in slightly alkaline surface water (pH 7.4–8.7) of oilsands tailings ponds in Fort McMurray, Canada. These large lakes (up to 10 km2) contain water, silt, clay and residual hydrocarbons that are not recovered in oilsands mining. They are primarily anoxic and produce methane but have an aerobic surface layer. Aerobic methane oxidation was measured in the surface water at rates up to 152 nmol CH4 ml−1 water d−1. Microbial diversity was investigated via py...

  19. PONDCALC - A Tool to Estimate Discharge from the Alviso Salt Ponds, California

    Science.gov (United States)

    Shellenbarger, Gregory; Schoellhamer, David H.; Lionberger, Megan A.

    2007-01-01

    Former commercial salt ponds in Alviso, California, now are operated by the U.S. Fish and Wildlife Service (USFWS) to provide habitat for birds. The USFWS has modified the operation of the ponds to prevent exceedingly high salinity. Ponds that were formerly hydraulically isolated from South San Francisco Bay and adjacent sloughs now are managed as flow-through ponds, and some are allowed to discharge to the Bay and sloughs. This discharge is allowed under a permit issued by the Regional Water Quality Control Board. As a requirement of the permit, the USFWS must estimate the amount of discharge from each discharge pond for the period May through November of each year. To facilitate the accurate estimation of pond discharge, a calculation methodology (hereafter referred to as 'calculator' or PONDCALC) for the discharging Alviso ponds has been developed as a Microsoft Excel file and is presented in this report. The presence of flap gates on one end of the discharge culverts, which allow only outflow from a pond, complicates the hydraulic analysis of flow through the culverts. The equation typically used for culvert flow contains an energy loss coefficient that had to be determined empirically using measured water discharge and head at the discharge structure of one of the ponds. A standard weir-flow equation is included in PONDCALC for discharge calculation in the ponds having weir box structures in addition to culverts. The resulting methodology is applicable only to the five Alviso ponds (A2W, A3W, A7, A14, and A16) that discharge to South San Francisco Bay or adjacent sloughs under the management practices for 2005.

  20. A COMPARATIVE DESCRIPTION OF THE ECOLOGICAL STATE OF NURSERY PONDS OF THE LVIV FISH FARM

    Directory of Open Access Journals (Sweden)

    A. Dobrjanska

    2014-06-01

    Full Text Available Purpose. Study of the ecological state of aquaculture ponds of the Lviv fish farms “Rudnyky” and “Derzhiv” for creation of optimum conditions for fish growing in ponds. Methodology. Growing of fish in the fish farm “Rudnyky” were conducted in the summer brood fish pond №12 of 4.2 ha area. The pond was stocked with yearlings of Lubin scaled and framed carps with an average weight of 83.3 g and stocking density of 1428 fish/ha. In the fish farm “Derzhiv”, growing of fish was conducted in the pond №1 of 4.2 ha area. The pond was stocked with fish larvae with stocking density of 18000 fish/ha. Determination of hydrochemical parameters was conducted using generally accepted analytical chemical methods. Quantitative determination of heavy metal content in water and bottom sediments was conducted by direct absorption in propane-butane flame with the aid of the absorption spectrophotometer C-115 M1. Findings. As a result of the conducted studies, we determined the pollution level of aquaculture ponds in the Lviv fish farms. Main hydrochemical indices, which characterize quality of water pond, meet norms for fish farming. All studied heavy metals in pond water of “Rudnyky” fish farm were at higher concentrations compared to those in the fish farm “Derzhiv”. Bottom sediments are characterized by a tendency of increasing nickel concentrations in both examined fish farms, values of which exceeded the maximum acceptable concentration. In the order of an increase of heavy metal content in bottom sediments, they can be ranged as Fe-Mn-Zn-Cd-Pb-Co-Cu-Ni. Originality. The ecological state of aquaculture ponds of the Lviv fish farms “Rudnyky” and “Derzhiv” has been investigated for the first time. Practical value. The obtained results of the ecological state of aquaculture ponds allow creating optimum conditions for growing of fish.

  1. Thermal evolutions of two kinds of melt pond with different salinity

    Science.gov (United States)

    Kim, Joo-Hong; Wilkinson, Jeremy; Moon, Woosok; Hwang, Byongjun; Granskog, Mats

    2016-04-01

    Melt ponds are water pools on sea ice. Their formation reduces ice surface albedo and alter surface energy balance, by which the ice melting and freezing processes are regulated. Thus, better understanding of their radiative characteristics has been vital to improve the simulation of melting/freezing of sea ice in numerical models. A melt pond would preserve nearly fresh water if it formed on multi-year ice and no flooding of sea water occurred, whereas a melt pond would contain more salty water if it formed on thinner and porous first-year ice, if there were an inflow of sea water by streams or cracks. One would expect that the fluid dynamic/thermodynamic properties (e.g., turbulence, stability, etc.) of pond water are influenced by the salinity, so that the response of pond water to any heat input (e.g., shortwave radiation) would be different. Therefore, better understanding of the salinity-dependent thermal evolution also has significant potential to improve the numerical simulation of the sea ice melting/freezing response to radiative thermal forcing. To observe and understand the salinity-dependent thermal evolution, two ice mass balance buoys (IMBs) were deployed in two kinds (fresh and salty) of melt pond on a same ice floe on 13 August 2015 during Araon Arctic cruise. The thermistor chain, extending from the air through the pond and ice into the sea water, was deployed through a drilled borehole inside the pond. Besides, the IMBs were also accompanied with three broadband solar radiation sensors (two (up and down) in the air over melt pond and one upward-looking under sea ice) to measure the net shortwave radiation at the pond surface and the penetrating solar radiation through ice. Also, the web camera was installed to observe any updates in the conditions of equipment and surrounding environment (e.g., weather, surface state, etc.). On the date of deployment, the fresh pond had salinity of 2.3 psu, light blue color, lots of slush ice particles which

  2. Energy flow along the medium-induced parton cascade

    Science.gov (United States)

    Blaizot, J.-P.; Mehtar-Tani, Y.

    2016-05-01

    We discuss the dynamics of parton cascades that develop in dense QCD matter, and contrast their properties with those of similar cascades of gluon radiation in vacuum. We argue that such cascades belong to two distinct classes that are characterized respectively by an increasing or a constant (or decreasing) branching rate along the cascade. In the former class, of which the BDMPS, medium-induced, cascade constitutes a typical example, it takes a finite time to transport a finite amount of energy to very soft quanta, while this time is essentially infinite in the latter case, to which the DGLAP cascade belongs. The medium induced cascade is accompanied by a constant flow of energy towards arbitrary soft modes, leading eventually to the accumulation of the initial energy of the leading particle at zero energy. It also exhibits scaling properties akin to wave turbulence. These properties do not show up in the cascade that develops in vacuum. There, the energy accumulates in the spectrum at smaller and smaller energy as the cascade develops, but the energy never flows all the way down to zero energy. Our analysis suggests that the way the energy is shared among the offsprings of a splitting gluon has little impact on the qualitative properties of the cascades, provided the kernel that governs the splittings is not too singular.

  3. 78 FR 56921 - South Bay Salt Pond Restoration Project, Phase 2 (Ponds R3, R4, R5, S5, A1, A2W, A8, A8S, A19...

    Science.gov (United States)

    2013-09-16

    ... Fish and Wildlife Service South Bay Salt Pond Restoration Project, Phase 2 (Ponds R3, R4, R5, S5, A1... restoration of ponds R3, R4, R5, S5, A1, A2W, A8, A8S, A19, A20, and A21 at the Don Edwards National Wildlife... 2 of the South Bay Salt Pond Restoration Project and consists of restoring and enhancing over...

  4. A comparative study of the growth of Tetraselmis sp. in large scale fixed depth and decreasing depth raceway ponds.

    Science.gov (United States)

    Das, Probir; Thaher, Mahmoud Ibrahim; Hakim, Mohammed Abdul Quadir Mohd Abdul; Al-Jabri, Hareb Mohammed S J; Alghasal, Ghamza Saed H S

    2016-09-01

    In this study, an alternative approach was proposed where excess seawater would be added only during inoculation (DD) rather than daily addition (FD). Growth and metabolite contents of Tetraselmis sp. weren't affected for daily increase of 2% NaCl salinity. Tetraselmis sp. was then cultured in DD and FD pond. In DD pond, initial culture depth was 23.5cm and its depth reduced as no water was added; for FD pond, everyday sterilized seawater was added to maintain 20cm depth. DD pond had higher biomass productivity compared to FD pond, until DD pond was deeper than FD pond; metabolite content and FAME profile of Tetraselmis sp. were also similar in both cultures. Therefore, considering the simplicity in operation, halo tolerant microalgae can be grown in DD pond method. PMID:27235973

  5. Sprays system of modern spray ponds for thermal power plants and nuclear power plants

    International Nuclear Information System (INIS)

    Design peculiarities of recently developed high-efficiency spray systems, intended for spray ponds at TEP and NPPs, are considered. Basic hydrodynamic characteristics of modern national circulation water spray systems are presented. Method for calculating optimal geometrical parameters of centrifugal nozzles relative to assigned thermal efficiency of spray pond is proposed. 11 refs., 3 figs., 1 tab

  6. Assessment of Zooplankton Size Fractionation for Monitoring Fry and Fingerling Culture Ponds

    Science.gov (United States)

    Methodology was formulated for use in the rapid assessment of zooplankton in channel catfish ponds. Understanding zooplankton prey size is useful for effective pond management. Size fractionation using differential sieve sizes was an effective means of separating size classes in live material, whe...

  7. Economic feasibility of an in-pond raceway system for commercial catfish production in west Alabama

    Science.gov (United States)

    The endeavor of this project was to improve profitability of catfish farming by demonstrating methods to achieve high levels of survival, feed performance, and efficiency in a commercial farm setting. A commercial-scale, in-pond raceway system was constructed in 2007 in a 6.0 ac earthen pond on a ca...

  8. 3D Modelling of Transport, Deposition and Resuspension of Highway Deposited Sediments in wet Detention Ponds

    DEFF Research Database (Denmark)

    Bentzen, Thomas Ruby

    2010-01-01

    The paper presents results from an experimental and numerical study of flows and transport of primarily particle bound pollutants in highway wet detention ponds. The study presented here is part of a general investigation on road runoff and pollution in respect to wet detention ponds. The objecti...

  9. REMOVAL OF HELMINTH PARASITIC EGGS FROM WASTE STABILIZATION PONDS AT SHIMOGA

    Directory of Open Access Journals (Sweden)

    M. SHANTHALA

    2007-01-01

    Full Text Available Helminth ova removal rates from waste stabilization pond effluents under tropical conditions ofShimoga using both laboratory and field modal ponds was undertaken. The helminthes were removedto the tune of 100% from laboratory model batch system ponds within 15 days of detention timeand it was only 65% in case of laboratory model continuos flow system ponds. The observation infield model ponds revealed an average 90% removal with 10 days retention time. A 100% removalcan not be expected both in continuous flow system laboratory model and field pond systems asthese receive daily fresh load of helminth eggs through influent sewage. The helminth ova are usallyremoved from waste stabilization ponds systems through sedimentation process. It is because thehelminth eggs attached to the suspended solids and when these solids settle to the bottom, the eggsare also removed from pelagic water. In the present study eggs of 4 helminth species viz. Ascarislumbricoides, Hymenolepis diminuta, Hymenolepis nana and Enterobius vermicularis wereencountered. Their rate of ova removal in batch system ponds was 99%, 97.4%, 94.9% and 98.8%for respective species. Presence of these ova in the sewage water indicates the prevalence of infectionin city population.

  10. Trace gas exchanges of marsh-pond-marsh constructed wetlands treating swine wastewater

    Science.gov (United States)

    Marsh-pond-marsh (MPM) constructed wetlands have been used effectively to treat wastewater from swine anaerobic lagoons. However, at high N loading rates, a significant portion of ammonia in the wastewater could be volatilized into the atmosphere. To mitigate ammonia emission, ponds can be covered w...

  11. DETERMINATION OF THE RATES AND PRODUCTS OF FERROUS IRON OXIDATION IN ARSENIC-CONTAMINATED POND WATER.

    Science.gov (United States)

    Dissolved ferrous iron and arsenic in the presence of insufficient oxygenated ground water is released into a pond. When the mixing of ferrous iron and oxygenated water within the pond occurs, the ferrous iron is oxidized and precipitated as an iron oxide. Groups of experiments...

  12. Aerial radiological surveys of Steed Pond, Savannah River Site: Dates of surveys, 1984--1989

    International Nuclear Information System (INIS)

    From June 1984 to August 1985, three aerial radiological surveys were conducted over Steed Pond at the Savannah River Site in South Carolina. In addition, Steed Pond was included in larger-area surveys of the Savannah River Site in subsequent years. The surveys were conducted by the Remote Sensing Laboratory of EG ampersand G Energy Measurements, Inc., Las Vegas, Nevada, for the US Department of Energy. Airborne measurements were obtained for both natural and man-made gamma radiation over Steed Pond and surrounding areas. The first survey was conducted when the pond was filled to normal capacity for the time of the year. On September 1, 1984, the Steed Pond dam spillway failed causing the pond to drain. The four subsequent surveys were conducted with the pond drained. The second survey and the third were conducted to study silt deposits exposed by the drop in water level after the spillway's opening. Steed Pond data from the February 1987 and April 1989 Savannah River Site surveys have been included to bring this study up to date

  13. Distribution of trematodes in snails in ponds at integrated small-scale aquaculture farms

    NARCIS (Netherlands)

    Boerlage, A.S.; Graat, E.A.M.; Verreth, J.A.J.; Jong, de M.C.M.

    2013-01-01

    In integrated small-scale aquaculture farming, animal and human excreta maybe used as fish feed and pond fertilizer, thereby enhancing transmission of fish-borne zoonotic trematodes (FZTs) from final hosts, like humans, pigs and chickens, to snails. Areas within a pond could vary in trematode egg-lo

  14. Nitrogen transformations and removal mechanisms in algal and duckweed stabilisation ponds

    NARCIS (Netherlands)

    Zimmo, O.

    2003-01-01

    This thesis describes the results of a comparative study of the performance of algae-based ponds (ABPs) and duckweed-based ponds (DBPs) for wastewater treatment, with emphasis on nitrogen transformations and removal mechanisms.Batch experiments simulating algae and duckweed ( Lemna gibba ) stabilisa

  15. Large contribution to inland water CO2 and CH4 emissions from very small ponds

    Science.gov (United States)

    Holgerson, Meredith A.; Raymond, Peter A.

    2016-03-01

    Inland waters are an important component of the global carbon cycle. Although they contribute to greenhouse gas emissions, estimates of carbon processing in these waters are uncertain. The global extent of very small ponds, with surface areas of less than 0.001 km2, is particularly difficult to map, resulting in their exclusion from greenhouse gas budget estimates. Here we combine estimates of the lake and pond global size distribution, gas exchange rates, and measurements of carbon dioxide and methane concentrations from 427 lakes and ponds ranging in surface area from 2.5 m2 to 674 km2. We estimate that non-running inland waters release 0.583 Pg C yr-1. Very small ponds comprise 8.6% of lakes and ponds by area globally, but account for 15.1% of CO2 emissions and 40.6% of diffusive CH4 emissions. In terms of CO2 equivalence, the ratio of CO2 to CH4 flux increases with surface area, from about 1.5 in very small ponds to about 19 in large lakes. The high fluxes from very small ponds probably result from shallow waters, high sediment and edge to water volume ratios, and frequent mixing. These attributes increase CO2 and CH4 supersaturation in the water and limit efficient methane oxidation. We conclude that very small ponds represent an important inland water carbon flux.

  16. 78 FR 59731 - License Amendment Request for Closure of Calcium Fluoride Ponds at Honeywell Metropolis Works...

    Science.gov (United States)

    2013-09-27

    ... COMMISSION License Amendment Request for Closure of Calcium Fluoride Ponds at Honeywell Metropolis Works... Honeywell International, Inc. (Honeywell) for its Metropolis Works Facility (MWF) in Metropolis, Illinois...: (1) License Amendment Request Report NRC License Number SUB-526, Closure of Retention Ponds B, C,...

  17. 78 FR 66056 - Sunkhaze Meadows National Wildlife Refuge and Carlton Pond Waterfowl Production Area, Penobscot...

    Science.gov (United States)

    2013-11-04

    ... and Carlton Pond WPA. We started this process through a notice in the Federal Register (76 FR 14984... Sunkhaze Meadows NWR and Carlton Pond WPA from April 23 to May 31, 2013 (78 FR 23949). During the comment... requesting comments in a notice of availability in the Federal Register (78 FR 23949). Currently,...

  18. An Instructional Design Using the Virtual Ecological Pond for Science Education in Elementary Schools

    Science.gov (United States)

    Tarng, Wernhuar; Ou, Kuo-Liang; Tsai, Wen-Shin; Lin, Yu-Si; Hsu, Chen-Kai

    2010-01-01

    Ecological ponds can be a good teaching tool for science teachers, but they must be built and maintained properly to provide students with a safe and suitable learning environment. However, many schools do not have the ability to build and maintain an ecological pond. This study used virtual reality technology to develop a web-based virtual…

  19. Effects of the mosquito larvicides temephos and methoprene on insect populations in experimental ponds

    Science.gov (United States)

    Pinkney, A.E.; McGowan, P.C.; Murphy, D.R.; Lowe, T.P.; Sparling, D.W.; Ferrington, L.C.

    2000-01-01

    The nontarget effects of Abate 4E ? (44.6% temephos) at 0.054 kg of active ingredient (a.i.) per 1 ha and of Altosid Liquid Larvicide ? (5% methoprene) at 0.011 kg a.i./ha were investigated in 18 experimental ponds (average area, 202 m2; maximum depth, 0.7 m) at Patuxent Wildlife Research Center, Laurel, Maryland, USA. Ponds were sprayed three times at 3-week intervals. Six ponds were sprayed with Abate, six with Altosid, and six with distilled water. Two insect-emergence traps per pond collected for 7 d and were then harvested 1 d before each spray and 13 to 14 days afterward. A repeated measures analysis of variance (ANOVA) revealed significant reductions in Shannon diversity, equatability, and numbers of individuals, species, and families in the Abate ponds relative to controls. Significant reductions also occurred in Ephemeroptera, Odonata, Diptera, Chironomidae, and Chaoborus sp. Hester-Dendy samplers were installed before spray one and harvested 16 d after spray three. Based on one-way ANOVA, Shannon diversity, equatability, and number of Ephemeroptera and Chironomidae were significantly reduced in the Abate ponds. Emergence data indicate only isolated cases with significant reductions in the Altosid ponds relative to controls, and the Hester-Dendy data indicate no significant differences between the Altosid and control ponds.

  20. Microbial Contamination of Community Pond Water in Dibrugarh District of Assam

    Directory of Open Access Journals (Sweden)

    Purnima Gogoi

    2013-04-01

    Full Text Available Our drinking water today, far from being pure, contains bacteria, viruses, inorganic minerals and a chemical cocktail that is unsuitable for human consumption. A study was undertaken with the objectives of evaluating the viable coliforms along with other water born bacteria in pond water environment. Water samples were collected from three community ponds of Dibrugarh district which are used mostly for bathing, watering livestock as well as drinking under water crises condition. Bacteria from collected pond samples were isolated by dilution plate technique. Coliform group in water was evaluated with the reference to EPA manual Microbiology Methods. The results showed that of the three ponds, pond 1 has highest number of bacterial counts (30x10 4 followed by pond 3 (24 x10 4 whereas pond 2 showed minimum colony count (12 x 10 3 per ml of water. The coliform bacteria count in the above pond water sample is far above the safety limit of WHO. Besides gram negative rod shaped coliform group, two groups of gram positive round shaped (with colony colour violet and orange and gram positive rod shaped bacteria group were also found dominant.

  1. Emergency power for fish produced in intensive, pond-based systems

    Science.gov (United States)

    Power failure in a heavily stocked and fed pond-based culture system can result in massive fish losses within minutes. Even in a conventional pond with a stand-by tractor powered aerator, the shock of a sudden loss of power can dramatically affect production resulting in mortalities and reduced perf...

  2. Constructed wetlands for water pollution management of aquaculture farms conducting earthen pond culture.

    Science.gov (United States)

    Lin, Ying-Feng; Jing, Shuh-Ren; Lee, Der-Yuan; Chang, Yih-Feng; Sui, Hsuan-Yu

    2010-08-01

    This study established farm-scale constructed wetlands integrated to shrimp ponds, using existing earthern pond areas, with a wetland-to-pond ratio of only 0.086 for shrimp culture. The constructed wetlands were used as practice for aquaculture water and wastewater treatment, to regulate the water quality of shrimp ponds and manage pollution from pond effluents. The results of water quality monitoring for influent and effluent showed that constructed wetlands significantly reduced total suspended solids (59 to 72%), turbidity (55 to 65%), chlorophyll a (58 to 72%), 5-day biochemical oxygen demand (29 to 40%), and chemical oxygen demand (13 to 24%) from pond water. The wetland treatment sufficiently regulated water quality of the recirculating shrimp pond, which was significantly (p shrimp pond, without the connection of constructed wetlands. Furthermore, the wetland-treated effluent satisfied the national effluent standards for aquaculture farms (R.O.C. Environmental Protection Administration, 2007). Accordingly, wetland treatment applications were proposed to implement the best management practices to reduce pollution from aquaculture farms in Taiwan. PMID:20853755

  3. Preferred Feeding Sites and Prey of the Adult Gold-spotted Pond Frog, Rana plancyi chosenica

    Directory of Open Access Journals (Sweden)

    Eom, Junho1

    2007-11-01

    Full Text Available To determine the feeding sites preferred by adult gold-spotted pond frogs, Rana plancyi chosenica,and the foods that induce favorable growth of the frogs in the laboratory, we conducted two separate experimentsbetween 27 May and 12 July 2007 in a vivarium. In the first experiment, we counted the number of cricketseaten by four gold-spotted pond frogs in a 60 min period at four different feeding sites within the experimentalarenas: on the water surface, at the edge of a pond, and at two terrestrial sites. Adult gold-spotted pond frogsate more crickets on the water surface and at the edge of the pond than the terrestrial sites. In the secondexperiment, we measured the growth of SVL (snout-vent length and body mass of adult gold-spotted pond frogsfed crickets, mealworms, maggots, or earthworms in individual experimental boxes over a one month period. TheSVL and body mass of the adult gold-spotted pond frogs fed crickets, mealworms, or maggots were greater thanthose of the frogs that were fed earthworms. These results indicate that providing crickets, mealworms, ormaggots on the water or at the edge of a pond should induce favorable growth of captive-reared adult goldspottedpond frogs.

  4. Comparing soil and pond ash feedlot pen surfaces for environmental management

    Science.gov (United States)

    Removing manure and replacing soil to maintain pen surfaces is expensive. Pond ash (PA), a coal-fired electrical generation by-product, has good support qualities. A study was conducted comparing the performance of pond ash (PA) surfaced pens with soil surface (SS) pens. Four pens of an eight pen se...

  5. Performance evaluation of pumping systems used in commercial-scale, split-pond aquaculture

    Science.gov (United States)

    Split-pond aquaculture systems have been adopted widely by United States catfish farmers as a way to improve production performance. The split-pond consists of a fish-culture basin that is connected to a waste-treatment lagoon by two water conveyance structures. Water is circulated between the two b...

  6. Pond preference by amphibians (Amphibia) on the Karst Plateau and in Slovenian Istria:

    OpenAIRE

    Francé, Janja

    2002-01-01

    Some habitat determinants and related presence of amphibians in 7 karst ponds in Slovenian Istria and 10 ponds on the Karst Plateau were surveyed from Marchto August 1999. The presence of different species of amphibians was established by sampling according to standard methods for amphibiand...

  7. Draft Genome Sequences of Campylobacterales (Epsilonproteobacteria) Obtained from Methanogenic Oil Sands Tailings Pond Metagenomes

    Science.gov (United States)

    Tan, BoonFei

    2014-01-01

    Draft genome sequences of two Campylobacterales (Sulfurospirillum sp. strain SCADC and Sulfuricurvum sp. strain MLSB [Mildred Lake Settling Basin]) were obtained by taxonomic binning of metagenomes originating from an oil sands tailings pond. Both genomes contain soxABXYZ genes involved in sulfur oxidation, highlighting their potential roles in sulfur cycling in oil sands tailings ponds. PMID:25323712

  8. Radioecological situation in fish ponds of the North regions of Ukraine

    International Nuclear Information System (INIS)

    The main objects of the research have been to analyze the radioactive contamination peculiarities of water,suspended matters,bottom sediments and hydrobionts in different ponds of the North regions of Ukraine.It has been stated that the Cs-137 concentration in fish of researched ponds is several times higher than the fish limits

  9. Corrosion electrochemistry of fuel element materials in pond storage conditions

    International Nuclear Information System (INIS)

    The integrity of spent fuel element clad is imperative in avoiding undesirable release of soluble fission products into cooling ponds following discharge from reactor into aqueous storage. Corrosion is a possible route to clad penetration and pond chemistry is controlled to maintain passivity. In order to allow optimisation of operating chemistry and hence minimise corrosion, the aqueous corrosion behaviours of commercial magnesium alloy Magnox Al80 and natural uranium have been studied with the use of modern electrochemical techniques. Historical corrosion investigations have generally employed conventional methods such as weight loss and hydrogen evolution which are often insensitive to certain mechanisms and require significant time-scales. Here the use of electrochemical noise and impedance spectroscopy alongside DC polarisation has allowed the study of general and localized corrosion, notably clad pitting, with greatly enhanced sensitivity and reduced time-scales. Significant practical benefits are also afforded, for example, the radiological wastes arising are reduced by shorter measurement times. Uranium exhibited a simple corrosion behaviour whilst Magnox corrosion proved to be a more complex and dynamic system. The formation of a passive layer and potential to subsequent breakdown are dictated by a number of factors, including pH and anion concentration as well as the presence of a crevice or galvanic couple. This has demanded the development and application of novel techniques and real time observations of pitting initiation and propagation have been made. (authors)

  10. Phosphorus cycling in the deep subseafloor biosphere at North Pond

    Science.gov (United States)

    Defforey, D.; Paytan, A.

    2013-12-01

    Phosphorus is a macronutrient involved both in functional and structural components of all living cells. This makes it an essential nutrient for life, including microbial life in the deep subseafloor habitat. Phosphorus availability in this environment is limited since it is thought to be mainly present in refractory mineral phases. However, recent estimates suggest that the deep biosphere may contain up to 1% of Earth's total biomass, which implies that microorganisms may possess mechanisms to harvest recalcitrant phosphorus compounds in this environment. This study sheds light on those mechanisms by investigating phosphorus cycling in deep open-ocean sediments using stable oxygen isotope ratios in phosphate. Furthermore, this study provides insight into changes in phosphorus bioavailability and mobility under a range of natural environmental conditions within the deep biosphere. Sediment samples were collected from four boreholes drilled during the IODP Expedition 336 to North Pond, an isolated sediment pond on the western flank of the Mid-Atlantic Ridge. Sedimentary phosphorus compounds are characterized using sequential extractions (SEDEX), which separate them into five distinct pools. Phosphate from the various extracts are then concentrated, purified through a series of steps, then converted to silver phosphate, which is pyrolyzed and analyzed by continuous-flow isotope ratio mass spectrometry (CF-IRMS). The isotopic signatures and/or fractionations associated with many of the potential reactions and transformations operating in the P cycle have been determined, and provide the basis for interpreting isotopic data that are obtained from the phosphate extracts.

  11. Cooling ponds and small rivers in north central United States

    International Nuclear Information System (INIS)

    An attempt is made to review those Commonwealth Edison (Ceco) programs related directly or indirectly to compensation and stock manipulation in fish populations. The direct stocking of sport fish fingerlings for mitigation is one method of stock manipulation. There are, however, two other, less common manipulative approaches to enhancing local fish stocks. First is the use of cooling ponds as off-stream nursery areas for forage and sport species. Second is the use of waste heat to modify habitat temperatures and permit or improve overwintering survival of select species such as gizzard or threadfin shad in north-temperate waters that are naturally too cold to sustain strong populations. This, in turn, will increase the abundance of these species as forage in subsequent years. There are four different Ceco projects which are discussed. These are: Fish releases in Pool 14 of the Mississippi River; Studies of endemic and stock fishes at the Collins and Dresden Cooling Ponds; Fish and water quality monitoring of the Des Plaines and Upper Illinois Rivers; and Proposed walleye, muskellunge and striped bass x white bass hybrid stocking in the Rock River. 7 references

  12. Use of stabilization pond sludge in cultivation of roses

    Directory of Open Access Journals (Sweden)

    Jorge L. da Paixão Filho

    2014-01-01

    Full Text Available One option for the increasing production of sewage sludge (SS is its agricultural use in crops with high nutritional demand, such as the rose. Therefore, the aim of this work was to study the application of SS from primary stabilization pond in roses of the variety 'Carola'. For the experiment, the roses were planted in 20 L recipients using increasing doses of sludge (T2 - 12 Mg ha-1, T3 - 24 Mg ha-1 and T4 - 36 Mg ha-1, mineral fertilizer (T5 and control treatment (T1, without N in a randomized block design. The evaluated parameters were: roots dry mass, aerial dry mass, total biomass, leaflets area and nitrogen concentration in the leaf. The SS application resulted in better development of the rose, increasing the roots and the aerial biomasses, the leaflets area, and nitrogen content in the leaves compared to the control (T1. There was no statistical difference between the use of mineral fertilizer (T5, and the SS under the highest dose (T4. With these benefits, the use in agriculture of sewage sludge derived from stabilization ponds proved to be an adequate option for its disposal.

  13. Impact of pond and fence aquaculture on reservoir environment

    Directory of Open Access Journals (Sweden)

    Huai-dong ZHOU

    2011-03-01

    Full Text Available With the rapid development of aquaculture in lakes and reservoirs, its negative effects on water quality and aquatic organisms are clearly emerging. Toward a better understanding of these effects, chemical and biological monitoring was conducted in the Fangbian Reservoir to study the relationship between aquaculture and eutrophication. As a domestic water supply source, this reservoir has reached the mesotrophic level. The concentrations of total nitrogen (TN and total phosphorus (TP in the Fangbian Reservoir have frequently exceeded the prescriptive level according to the Environmental Quality Standards for Surface Water (GB3838-2002. Pond and fence aquaculture feeding is the main cause of high levels of nitrogen and phosphorus, accounting for nearly half of the total pollution, and causing the reservoir environmental capacity to be exceeded. The amounts of nitrogen and phosphorus that went directly to the reservoir through the residual bait and fish droppings in fence aquaculture were 42 768 kg per year and 10 856 kg per year respectively, from 2007 to 2009. About 2 913 kg of nitrogen and 450 kg of phosphorus were imported to the reservoir through the exchange of water from the culturing ponds at the same time. Therefore, controlling the aquaculture scale and promoting eco-aquaculture are key measures for lessening the eutrophication degree and improving the water quality.

  14. Retention deficit: Evaluating retention pond effectiveness at controlling suburban stormwater runoff, James City County, Virginia

    Science.gov (United States)

    Hancock, G. S.; Popkin, M. B.

    2005-12-01

    Stormwater retention ponds (SRP) have become a significant component of suburban hydrology. SRPs are designed to protect streams by releasing storm runoff slowly, reducing peak flows generated from developed surfaces. Despite widespread use, little data has been collected to assess their success at controlling stormwater quantity. We present data from two SRPs in James City County, Virginia, to assess whether they manage stormwater as designed and achieve stream protection goals. Pond A collects runoff from a ~7 acre residential development (~23 homes on ~0.25 acre lots), and Pond B collects runoff from a ~22 acre development (~50 homes on ~0.3 acre lots). The SRPs are designed to retain the runoff produced by the one year, 24 hr storm (2.8 inches) for 24 hrs as well as to reduce peak discharge below uncontrolled conditions. At each pond, a pressure transducer connected to a datalogger records pond elevation every 15 min, from which pond outflow and inflow are obtained. A tipping bucket raingage at each site records rainfall totals. We analyzed data for 16 significant rainfall events from July through December 2004. All rainfall was less than the one yr, 24 hr design storm, and pond flows should therefore be less than the flow expected to occur in such an event. However, pond flows frequently exceeded this threshold. At Pond A, flows exceeded that predicted for the one year storm at least four times. Inflow exceeded the predicted 2 yr storm response four times, and outflow exceeded the 25 yr storm response three times. At Pond B, inflow exceeded the one yr storm response five times, while outflow exceeded the one yr storm response nine times, with one exceedence of the 10 yr outflow. In 16 events, Pond A met the 24 hr runoff detention goal only once, with detention ranging from 0.5 -10.5 hrs during other events. These results suggest that these SRPs receive and release higher peak discharges than intended, and often release captured stormwater over periods much

  15. Chemical aspects of the commissioning and early operation of the BNL pond water treatment plant

    International Nuclear Information System (INIS)

    An account is given of the chemical aspects of the work done in commissioning and setting-to-work the pond water treatment plant at BNL. The plant is designed to maintain the fuel pond within the specified chemical conditions for Magnox fuel storage. In normal operation the treatment requirements are met by anion exchange, i.e. the carbonate and other impurity anions in the pond water are replaced by hydroxide held on an anion exchange resin. This method is referred to as ''anion only''. In the commissioning tests the performance of the plant was substantiated by passing simulated pond water of the correct chemical composition through the plant and monitoring the water quality at the plant outlet. During the first phase of operation on the pond itself the plant was operated in non-standard fashion to convert the chemistry from the previous ''carbonate'' regime to the required conditions. (author)

  16. An investigation of the treatment of simulated Magnox fuel pond water by electrodialysis

    International Nuclear Information System (INIS)

    The cooling ponds for irradiated Magnox fuel are dosed with sodium hydroxide to protect the fuel cladding from corrosion. Carbon dioxide is absorbed by the pond water, and treatment is necessary to maintain alkalinity. The pond water treatment also controls the level of other trace impurities that can be detrimental to the fuel cladding. Ion exchange plants have been installed on all Magnox Power Station cooling ponds. Whilst these plants work quite satisfactorily, they involve a continual input of chemicals and an effluent which can be radioactively contaminated. Electrodialysis is a technique that employs ion exchange membranes rather than resin beads to alter the ionic constituents in the water. Energy is provided in electrical form, rather than chemical form as in the ion exchange regeneration. The report is an experimental investigation of the applicability of electrodialysis to Magnox fuel pond water treatment. (U.K.)

  17. Dewatering and RCRA partial closure action on solar evaporation ponds, Rocky Flats Plant, Golden, Colorado

    International Nuclear Information System (INIS)

    The Department of Energy (DOE) has prepared an Environmental Assessment (DOE/EA-0487) on its proposal to partially close five solar evaporation ponds at the Rocky Flats Plant (RFP) pursuant to the requirements of the Resource Conservation and Recovery Act (RCRA). This proposal would be known as a RCRA partial closure and would be accomplished by dewatering the ponds, where necessary, and converting any remaining sludge or evaporator concentrate to a solid wasteform (pondcrete and saltcrete). The pond sites would be stabilized to prevent erosion or other disturbance to the soil and to prevent infiltration of rain or snowmelt. The solid wasteform would be transported offsite for disposal. The five solar ponds (designated 207-A, 207-B (north, center, and south), and 207-C), are the only solar evaporation ponds that exist at the RFP. A finding of no significant impact is included

  18. Snow Dunes: A Controlling Factor of Melt Pond Distribution on Arctic Sea Ice

    Science.gov (United States)

    Petrich, Chris; Eicken, Hajo; Polashenski, Christopher M.; Sturm, Matthew; Harbeck, Jeremy P.; Perovich, Donald K.; Finnegan, David C.

    2012-01-01

    The location of snow dunes over the course of the ice-growth season 2007/08 was mapped on level landfast first-year sea ice near Barrow, Alaska. Landfast ice formed in mid-December and exhibited essentially homogeneous snow depths of 4-6 cm in mid-January; by early February distinct snow dunes were observed. Despite additional snowfall and wind redistribution throughout the season, the location of the dunes was fixed by March, and these locations were highly correlated with the distribution of meltwater ponds at the beginning of June. Our observations, including ground-based light detection and ranging system (lidar) measurements, show that melt ponds initially form in the interstices between snow dunes, and that the outline of the melt ponds is controlled by snow depth contours. The resulting preferential surface ablation of ponded ice creates the surface topography that later determines the melt pond evolution.

  19. Massive subsurface ice formed by refreezing of ice-shelf melt ponds

    Science.gov (United States)

    Hubbard, Bryn; Luckman, Adrian; Ashmore, David W.; Bevan, Suzanne; Kulessa, Bernd; Kuipers Munneke, Peter; Philippe, Morgane; Jansen, Daniela; Booth, Adam; Sevestre, Heidi; Tison, Jean-Louis; O'Leary, Martin; Rutt, Ian

    2016-06-01

    Surface melt ponds form intermittently on several Antarctic ice shelves. Although implicated in ice-shelf break up, the consequences of such ponding for ice formation and ice-shelf structure have not been evaluated. Here we report the discovery of a massive subsurface ice layer, at least 16 km across, several kilometres long and tens of metres deep, located in an area of intense melting and intermittent ponding on Larsen C Ice Shelf, Antarctica. We combine borehole optical televiewer logging and radar measurements with remote sensing and firn modelling to investigate the layer, found to be ~10 °C warmer and ~170 kg m-3 denser than anticipated in the absence of ponding and hitherto used in models of ice-shelf fracture and flow. Surface ponding and ice layers such as the one we report are likely to form on a wider range of Antarctic ice shelves in response to climatic warming in forthcoming decades.

  20. A highly sensitive underwater video system for use in turbid aquaculture ponds.

    Science.gov (United States)

    Hung, Chin-Chang; Tsao, Shih-Chieh; Huang, Kuo-Hao; Jang, Jia-Pu; Chang, Hsu-Kuang; Dobbs, Fred C

    2016-01-01

    The turbid, low-light waters characteristic of aquaculture ponds have made it difficult or impossible for previous video cameras to provide clear imagery of the ponds' benthic habitat. We developed a highly sensitive, underwater video system (UVS) for this particular application and tested it in shrimp ponds having turbidities typical of those in southern Taiwan. The system's high-quality video stream and images, together with its camera capacity (up to nine cameras), permit in situ observations of shrimp feeding behavior, shrimp size and internal anatomy, and organic matter residues on pond sediments. The UVS can operate continuously and be focused remotely, a convenience to shrimp farmers. The observations possible with the UVS provide aquaculturists with information critical to provision of feed with minimal waste; determining whether the accumulation of organic-matter residues dictates exchange of pond water; and management decisions concerning shrimp health. PMID:27554201