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Статті в журналах з теми "DOWN STREEM LENGHT"
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Shabtaie, S., and C. R. Bentley. "Ice-Thickness Map of the West Antarctic Ice Streams by Radar Sounding." Annals of Glaciology 11 (1988): 126–36. http://dx.doi.org/10.3189/s0260305500006443.
Повний текст джерелаАнотація:
Extensive radar ice-thickness sounding of ice streams A, B, and C, and the ridges between them, has been carried out. Closely spaced flight lines, as well as ties to numerous ground stations, have enabled us to compile a detailed ice-thickness map of the area. The map reveals a highly complex pattern of ice-thickness variations, which, because they are much larger than the surface relief, largely reflect the subglacial topography. Several cross-sectional profiles across the ice streams and ridges are shown, and a new configuration for Ice Stream A is presented.Ice Stream A is connected to Reedy Glacier and Horlick Ice Stream by subglacial troughs that converge down-stream. The single trough continues, at a depth of more than 1000 m below sea-level, beneath the entire length of the ice stream and adjacent part of Ross Ice Shelf. Ridge AB (part of which may be a remanent ice stream) overlies a deep bed with pronounced troughs at its headward end; the bed shoals rapidly down-stream to a height more than 500 m above the beds of the adjacent ice streams. Ice stream B1 overlies a subglacial trough that is deep inland and also shoals markedly toward the grounding line. Near its head. Ice Stream B2 is as much as 1000 m thinner than Ice Stream Bl, but then remains much more nearly constant in thickness along its length. Ridge BC is characterized by a smoother bed and less variation in bed depth than ridge AB. Ice Stream C, which is inactive, is particularly marked by uncorrelated maxima and minima in surface and bed topography.There are no distinct topographical steps that demarcate the transition from sheet to streaming flow at the head of the ice streams, and the ice streams are placed asymmetrically in some places with respect to their subglacial troughs. This may reflect a relative impermanence or transient behavior of the “Ross” ice streams.
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Shabtaie, S., and C. R. Bentley. "Ice-Thickness Map of the West Antarctic Ice Streams by Radar Sounding." Annals of Glaciology 11 (1988): 126–36. http://dx.doi.org/10.1017/s0260305500006443.
Повний текст джерелаАнотація:
Extensive radar ice-thickness sounding of ice streams A, B, and C, and the ridges between them, has been carried out. Closely spaced flight lines, as well as ties to numerous ground stations, have enabled us to compile a detailed ice-thickness map of the area. The map reveals a highly complex pattern of ice-thickness variations, which, because they are much larger than the surface relief, largely reflect the subglacial topography. Several cross-sectional profiles across the ice streams and ridges are shown, and a new configuration for Ice Stream A is presented. Ice Stream A is connected to Reedy Glacier and Horlick Ice Stream by subglacial troughs that converge down-stream. The single trough continues, at a depth of more than 1000 m below sea-level, beneath the entire length of the ice stream and adjacent part of Ross Ice Shelf. Ridge AB (part of which may be a remanent ice stream) overlies a deep bed with pronounced troughs at its headward end; the bed shoals rapidly down-stream to a height more than 500 m above the beds of the adjacent ice streams. Ice stream B1 overlies a subglacial trough that is deep inland and also shoals markedly toward the grounding line. Near its head. Ice Stream B2 is as much as 1000 m thinner than Ice Stream Bl, but then remains much more nearly constant in thickness along its length. Ridge BC is characterized by a smoother bed and less variation in bed depth than ridge AB. Ice Stream C, which is inactive, is particularly marked by uncorrelated maxima and minima in surface and bed topography. There are no distinct topographical steps that demarcate the transition from sheet to streaming flow at the head of the ice streams, and the ice streams are placed asymmetrically in some places with respect to their subglacial troughs. This may reflect a relative impermanence or transient behavior of the “Ross” ice streams.
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Perkin, Joshuah S., Keith B. Gido, Jeffrey A. Falke, Kurt D. Fausch, Harry Crockett, Eric R. Johnson, and John Sanderson. "Groundwater declines are linked to changes in Great Plains stream fish assemblages." Proceedings of the National Academy of Sciences 114, no. 28 (June 26, 2017): 7373–78. http://dx.doi.org/10.1073/pnas.1618936114.
Повний текст джерелаАнотація:
Groundwater pumping for agriculture is a major driver causing declines of global freshwater ecosystems, yet the ecological consequences for stream fish assemblages are rarely quantified. We combined retrospective (1950–2010) and prospective (2011–2060) modeling approaches within a multiscale framework to predict change in Great Plains stream fish assemblages associated with groundwater pumping from the United States High Plains Aquifer. We modeled the relationship between the length of stream receiving water from the High Plains Aquifer and the occurrence of fishes characteristic of small and large streams in the western Great Plains at a regional scale and for six subwatersheds nested within the region. Water development at the regional scale was associated with construction of 154 barriers that fragment stream habitats, increased depth to groundwater and loss of 558 km of stream, and transformation of fish assemblage structure from dominance by large-stream to small-stream fishes. Scaling down to subwatersheds revealed consistent transformations in fish assemblage structure among western subwatersheds with increasing depths to groundwater. Although transformations occurred in the absence of barriers, barriers along mainstem rivers isolate depauperate western fish assemblages from relatively intact eastern fish assemblages. Projections to 2060 indicate loss of an additional 286 km of stream across the region, as well as continued replacement of large-stream fishes by small-stream fishes where groundwater pumping has increased depth to groundwater. Our work illustrates the shrinking of streams and homogenization of Great Plains stream fish assemblages related to groundwater pumping, and we predict similar transformations worldwide where local and regional aquifer depletions occur.
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Gürkan, elin Ertürk. "Circumstantial evidence of effect of trout farming on length-weight relations of native fish species: Barbus oligolepis (Battalgil, 1941) and Squalius cii (Richardson, 1857)." Journal of Aquaculture & Marine Biology 9, no. 3 (2020): 87–90. http://dx.doi.org/10.15406/jamb.2020.09.00282.
Повний текст джерелаАнотація:
This study was carried out to reveal how the aquaculture activities, located near the stream bed, effect the length-weight relations of native freshwater fish. Fish samples were collected on monthly for one year on the Kocabaş Stream (Çanakkale), a trout farm constructed next to stream. Fish specimens were collected from up and down sections of the trout farm and control station selected from another branch of the stream by electrofishing between August 2015-July 2016. The growth type sign; b value in length-weight relationship indicates that both species are in positive allometry at the down station and isometric growth at the upper station. Fish farm might affect the growth type of both species positively due to contribution of extra food resources originated from the farm via discharge of waste water of trout farm at the down section. However, this hypothesis should be tested by proper growth parameters of the fish species.
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Mua, Kang Edwin, and Kometa Sunday Shende. "The Response of Stream Competence to Topographic and Seasonal Variations in The Bamenda-Menchum Drainage Basin, North West Region, Cameroon." Journal of Geography and Geology 11, no. 2 (May 30, 2019): 21. http://dx.doi.org/10.5539/jgg.v11n2p21.
Повний текст джерелаАнотація:
The flow direction of streams remains an establishing mechanism in understanding drainage basin function and stream competence. The ability of streams to erode, transport and deposit loads in fluvial geomorphology exert a benchmark precursor for slope dynamics given the differential geological outcrop of the Bamenda-Menchum basin. Such competence in stream network generates slope instability as materials continuously move down slope from the volcanic escarpment face of Bamenda highlands to the sedimentary lowland area of Lower Bafut-Menchum basin. This paper investigate the influence of stream flow direction and stream competence on slope dynamics and how such dynamism affects the development prospects of the drainage basin. Slope range was obtained from AVL/EBI.JHO measurement. Stream length, density and flow direction were gotten from GIS Arc 21. Stream depth, channel width, flow rate and sedimentation levels were measured. Gully depth on slopes and landslide angles were measured using 30m tape and a graduated pole. Questionnaires were used to collect information on the vulnerability of households to slope dynamics orchestrated by stream competence. Findings revealed that stream competence varies from the two geological basements and that the escarpment face respond to high flow gravity and hydraulic action contributing to rapid erosion and transportation of loads. The results equally showed that the Bamenda escarpment face that is linked to the crystalline rocks produce differential erosion and landslide. 76.7% of slope instability is explained by geological structure and seasonality effect in the basin while 23.3% of slope dynamics is explained by other variables not specified in the study. The lower basin remains liable to deposition of materials on river channels and flood plain. The accumulation of sand, stones and alluvial deposits are extracted and exploited for the development prospects of the basin. The study recommends channel and slope management by integrating slope development control policy in drainage basin management and development.
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Agarwal, N. K., and Gurnam Singh. "Documentation of fishes and physico-chemical characters of a stream Indrawati- a spring fed tributary of River Bhagirathi at Uttarkashi (Central Himalaya, Garhwal) India." Environment Conservation Journal 13, no. 3 (December 20, 2012): 117–24. http://dx.doi.org/10.36953/ecj.2012.130319.
Повний текст джерелаАнотація:
Most of the riverine resources in Garhwal region are mountainous and perennial either snow fed or spring originated. All these mountainous streams provide a good natural habitat for survival of hill stream fishes. Present communication deals with documentation of Ichthyofauna along with physico-chemical properties of a similar perennial spring fed stream Indrawati- a left side tributary of river Bhagirathi. It comes down from the hills of Baragari and through Joshiyara debouches into the river Bhagirathi at Uttarkashi (elevation 1128 masl). Major part of stream water is mainly abstracted for the irrigation purpose in the side lying fields all along its length. There is heterogeneity in the stream bed characteristics which results into the existence of varied fish fauna. Study reports eleven fish species from the stream belonging to two orders, three families and six genera. Fishes belonging to cyprinidae family are found more commonly than the cobitidae and sisoridae family. Fishery of the stream is of subsistence nature and is under intense pressure of anthropogenic activities. Fishes captured are of generally small sized. The physico-chemical characteristics recorded during the study period in the different seasons are water temperature (9.0-16.0 0C), velocity (.50 m-s-1.46 m-s), TDS (49 mg-l – 65 mg-l), pH (8.0 - 8.3), DO (7.3 mg-l – 10.5 mg-l), Free CO2 (0.10 mg-l – 0.30 mg-l) and turbidity (06-30 NTU).
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Gilbert, O. L., and V. J. Giavarini. "The Lichen Vegetation of Acid Watercourses in England." Lichenologist 29, no. 4 (July 1997): 347–67. http://dx.doi.org/10.1006/lich.1997.0090.
Повний текст джерелаАнотація:
AbstractThe lichen vegetation of forty-five acid watercourses in England is described and related to ecological variables. The zonation scheme adopted for chalk and limestone streams that involves four overlapping bands of lichen vegetation related to length of submergence is also appropriate for this habitat. The flora involves around 90 species, a number of which are rarely recorded specialists. Evidence is presented that substratum chemistry is a more powerful ecological factor than water chemistry. An attempt has been made to relate the lichen flora to homogeneous stream segments from the headwaters down to the alluvial lowlands. An investigation into the effects of water quality showed that both suspended solids (silting) and eutrophication are highly deleterious to the lichen flora; the submerged and fluvial mesic zones are the first to be affected. The zonation across streams in England is compared with those reported from Germany and found to be closely similar.
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Amrender Singh, Bachhal, Vogstad Klaus, Lal Kolhe Mohan, Chougule Abhijit, and Beyer Hans George. "Wake and Turbulence Analysis for Wind Turbine Layouts in an Island." E3S Web of Conferences 64 (2018): 06010. http://dx.doi.org/10.1051/e3sconf/20186406010.
Повний текст джерелаАнотація:
There is a big wind energy potential in supplying the power in an island and most of the islands are off-grid. Due to the limited area in island(s), there is need to find appropriate layout / location for wind turbines suited to the local wind conditions. In this paper, we have considered the wind resources data of an island in Trøndelag region of the Northern Norway, situated on the coastal line. The wind resources data of this island have been analysed for wake losses and turbulence on wind turbines for determining appropriate locations of wind turbines in this island. These analyses are very important for understanding the fatigue and mechanical stress on the wind turbines. In this work, semi empirical wake model has been used for wake losses analysis with wind speed and turbine spacings. The Jensen wake model used for the wake loss analysis due to its high degree of accuracy and the Frandsen model for characterizing the turbulent loading. The variations of the losses in the wind energy production of the down-wind turbine relative to the up-wind turbine and, the down-stream turbulence have been analysed for various turbine distances. The special emphasis has been taken for the case of wind turbine spacing, leading to the turbulence conditions for satisfying the IEC 61400-1 conditions to find the wind turbine layout in this island. The energy production of down-wind turbines has been decreased from 2 to 20% due to the lower wind speeds as they are located behind up-wind turbine, resulting in decreasing the overall energy production of the wind farm. Also, the higher wake losses have contributed to the effective turbulence, which has reduced the overall energy production from the wind farm. In this case study, the required distance for wind turbines have been changed to 6 rotor diameters for increasing the energy gain. From the results, it has been estimated that the marginal change in wake losses by moving the down-stream wind turbine by one rotor diameter distance has been in the range of 0.5 to 1% only and it is insignificant. In the full-length paper, the wake effects with wind speed variations and the wind turbine locations will be reported for reducing the wake losses on the down-stream wind turbine. The Frandsen model has been used for analysing turbulence loading on the down-stream wind turbine as per IEC 61400-1 criteria. In larger wind farms, the high turbulence from the up-stream wind turbines increases the fatigues on the turbines of the wind farm. In this work, we have used the effective turbulence criteria at a certain distance between up-stream and down-stream turbines for minimizing the fatigue load level. The sensitivity analysis on wake and turbulence analysis will be reported in the full-length paper. Results from this work will be useful for finding wind farm layouts in an island for utilizing effectively the wind energy resources and electrification using wind power plants.
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Jumper, G. W., W. C. Elrod, and R. B. Rivir. "Film Cooling Effectiveness in High-Turbulence Flow." Journal of Turbomachinery 113, no. 3 (July 1, 1991): 479–83. http://dx.doi.org/10.1115/1.2927899.
Повний текст джерелаАнотація:
The mechanisms influencing film cooling effectiveness on a flat plate in high free-stream turbulence using a single row of 30 deg slant-hole injectors are examined. The primary area of focus is the area within 40 diameters downstream of injection. Of interest are blowing ratios for optimum film cooling effectiveness within 10 diameters downstream of injection, and the decay of film cooling effectiveness down the plate. Film cooling flow Reynolds numbers. Re, from 24,700 to 86,600 and free-stream turbulence intensities from 14 to 17 percent were examined. Changes in Reynolds number or free-stream turbulence broadened and increased the blowing ratios for optimum film cooling effectiveness. In comparison with tests conducted at 0.5 percent free-stream turbulence, higher free-stream turbulence causes a faster decay in film cooling effectiveness, or a reduction in the effective cooling length, and a reduction of the level of cooling effectiveness at the higher Reynolds numbers.
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Wang, D., K. Li, and W. K. Teo. "Membrane vacuum stripping process for volatile organics removal from water using an asymmetric PVDF (polyvinylidene fluoride) hollow fiber membrane module." Water Supply 1, no. 5-6 (June 1, 2001): 65–75. http://dx.doi.org/10.2166/ws.2001.0101.
Повний текст джерелаАнотація:
The vacuum membrane stripping process (VMS) for removing a VOC (trichloroethylene) from water was studied in a polyvinylidene fluoride (PVDF) hollow fiber membrane module containing 187 fibers with a length of 0.59 m. The porous PVDF asymmetric hollow fiber used was prepared by the wet phase inversion technique. The feed solution containing trichloroethylene (TCE) was passed through the lumen of the PVDF hollow fiber. Vapors of TCE and water were transported through the pores of the membrane into the shell side maintained at a sub-atmospheric pressure, and condensed in cold traps. The effects of down-stream pressure, solution temperature, feed concentration, and feed flow rate on TCE removal, TCE permeation flux, water permeation flux and TCE concentration of the permeated solution, as well as the mass transfer coefficient were investigated. The down stream pressure and solution temperature were identified as the major factors to control VOC removal and TCE concentration in the permeate stream. A small amount of the permeated solution with higher TCE concentration was obtained at the temperature of 50°C and pressure of 80 mmHg when about 90% TCE was removed from the water.
Дисертації з теми "DOWN STREEM LENGHT"
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ARYA, ADITYA. "SCOUR AROUND DIFFERENT SHAPES OF PIERS AT DIFFERENT ORIENTATION WITH FLOW." Thesis, 2014. http://dspace.dtu.ac.in:8080/jspui/handle/repository/15500.
Повний текст джерелаАнотація:
Scour is the process of local lowering of stream bed elevation which takes place in the vicinity or around a structure constructed in flowing water. Scour takes place around bridge piers, abutments, around spurs, jetties and breakwaters due to modification of flow pattern in such a way as to cause increase in local shear stress. Due to improper knowledge of scour around bridge pier, there were lots of bridges failure cases faces by our country which leads to economic loss and life loss. To understand the phenomenon of local scour around piers an attempt is done by experiment on different shape of bridge piers at different angle of attack of flow.
A series of experiments were performed to study the phenomenon of local scour that takes place beside a bridge pier of different shape on straight channel at different angle of attack, and to investigate the relation between the dimensions of the scour hole and between non-dimensional parameters describing the flow ratio, and angle of flow attack. All tests were held under clear-water condition, using a horizontal bed consisted of non-uniform sandy soil.
The experiments were conducted under different condition of flow parameters which helps to better understanding of local scour around different shapes of piers, and piers along the channel flow, across the channel flow and inclined to channel flow. The shape of scour hole, depth of scour, length of scour hole upstream and length of scour hole downstream helps in understanding geometry of scour hole and rate of scour in different cases of piers shape and orientation.
Under the different condition of flow, its helps to understanding the scour depth variation with time, with parts run of flow and with continuous flow run in a certain time. The others parameters like length of scour hole upstream and downstream to study the variation of geometry of scour hole.
With the different shape of piers, the pier having minimum scour is best for the design consideration for scour point of view, it also helps in designing of foundation as the increasing depth of foundation increase the cost of project with proper knowledge about scour phenomenon helps in designing cost effective piers.
Частини книг з теми "DOWN STREEM LENGHT"
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"Community Ecology of Stream Fishes: Concepts, Approaches, and Techniques." In Community Ecology of Stream Fishes: Concepts, Approaches, and Techniques, edited by Keith B. Gido, Katie N. Bertrand, Justin N. Murdock, Walter K. Dodds, and Matt R. Whiles. American Fisheries Society, 2010. http://dx.doi.org/10.47886/9781934874141.ch29.
Повний текст джерелаАнотація:
<em>Abstract</em>.—Stream fishes can have strong top-down and bottom-up effects on ecosystem processes. However, the dynamic nature of streams constrains our ability to generalize these effects across systems with different disturbance regimes and species composition. To evaluate the role of fishes following disturbance, we used a series of field and mesocosm experiments that quantified the influence of grazers and water column minnows on primary productivity, periphyton structure, organic matter pools, and invertebrate communities following either scouring floods or drying of prairie streams. Results from individual experiments revealed highly significant effects of fishes, but the direction or magnitude of effects varied among experiments. Meta-analyses across experiments indicated that grazers consistently reduced the relative amount of fine benthic organic matter (FBOM) and chironomid abundance within 2 weeks after disturbances. However, effect sizes (log response ratios) were heterogeneous across experiments for algal biomass and algal filament lengths measured more than 4 weeks after a disturbance and potentially associated with system productivity and grazer densities. A similar analysis of 3–4 experiments using water column minnows only found a consistent trend of decreasing FBOM in fish treatments relative to controls when measured less than 2 weeks after disturbances and increase in gross primary productivity measured more than 4 weeks after disturbance. These results, along with those of others, were used to develop a conceptual framework for predicting the potential role of fishes in streams following disturbances (flood and drying). Both theoretical and empirical research shows that recovery of stream ecosystem processes will depend on the resilience of autotrophic and heterotrophic communities following disturbance. Fish effects may vary among functional groups but are generally predicted to be greatest during early stages of succession when algal and invertebrate communities are less complex and their biomass is low relative to fish biomass. Our analysis underscores the context dependency of consumer effects on ecosystem structure and function in nonequilibrium conditions and suggests that factors regulating fish densities and colonization of algal and invertebrate taxa need to be evaluated to predict the consequences of biodiversity loss in streams with variable or human-modified disturbance regimes.
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Gladwell, Malcolm. "Designs for Working : Why Your Bosses Want to Turn Your New Office into Greenwich Village." In Networks in the Knowledge Economy. Oxford University Press, 2003. http://dx.doi.org/10.1093/oso/9780195159509.003.0012.
Повний текст джерелаАнотація:
In the early 1960s, Jane Jacobs lived on Hudson Street, in Greenwich Village, near the intersection of Eighth Avenue and Bleecker Street. It was then, as now, a charming district of nineteenth-century tenements and townhouses, bars and shops, laid out over an irregular grid, and Jacobs loved the neighborhood. In her 1961 masterpiece, “The Death and Life of Great American Cities,” she rhapsodized about the White Horse Tavern down the block, home to Irish longshoremen and writers and intellectuals— a place where, on a winter’s night, as “the doors open, a solid wave of conversation and animation surges out and hits you.” Her Hudson Street had Mr. Slube, at the cigar store, and Mr. Lacey, the locksmith, and Bernie, the candy-store owner, who, in the course of a typical day, supervised the children crossing the street, lent an umbrella or a dollar to a customer, held on to some keys or packages for people in the neighborhood, and “lectured two youngsters who asked for cigarettes.” The street had “bundles and packages, zigzagging from the drug store to the fruit stand and back over to the butcher’s,” and “teenagers, all dressed up, are pausing to ask if their slips show or their collars look right.” It was, she said, an urban ballet. The miracle of Hudson Street, according to Jacobs, was created by the particular configuration of the streets and buildings of the neighborhood. Jacobs argued that when a neighborhood is oriented toward the street, when sidewalks are used for socializing and play and commerce, the users of that street are transformed by the resulting stimulation: they form relationships and casual contacts they would never have otherwise. The West Village, she pointed out, was blessed with a mixture of houses and apartments and shops and offices and industry, which meant that there were always people “outdoors on different schedules and . . . in the place for different purposes.” It had short blocks, and short blocks create the greatest variety in foot traffic. It had lots of old buildings, and old buildings have the low rents that permit individualized and creative uses.
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Carr, Jeremy. "Setting the Scene." In Repulsion, 71–86. Liverpool University Press, 2021. http://dx.doi.org/10.3828/liverpool/9781800859326.003.0005.
Повний текст джерелаАнотація:
In terms of its jarring camera movement, its multilayered sound design, its canted angles and intense close-ups, special effects, skewed subjectivity, and even its use of conventional shock cuts and transitions, Repulsion is one of the more audaciously stylish of Polanski’s films. A sullen camera will hold on Carol as she lies down or sits and stares, the relative inaction triggering the sensation of impending discord while the stress on concentrated stillness and silence induces a slow burn decline into madness. Polanski’s camera wanders in meditative tracks and pans and scenes end in slow fades to black, prodding the mounting pressure by way of wearing down the surface stability to uncover an ingrained horror. And just as Carol’s edgy, deliberate movements are bolstered by duration, her descent is illustrated in distorted imagery, irregular focal lengths, wide lenses, and low angles. Polanski also embraces common horror practice by teasing imminent jeopardy, providing the viewer with knowledge characters don’t have and he infuses the picture with such classically frightening scares as an uncanny figure glimpsed in a flash and the violent release of Carol as she slashes wildly at her victims or pummels them without mercy.
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Hazlitt, William. "William Godwin." In The Spirit of Controversy, edited by Jon Mee and James Grande. Oxford University Press, 2021. http://dx.doi.org/10.1093/owc/9780199591954.003.0028.
Повний текст джерелаАнотація:
The Spirit of the Age was never more fully shewn than in its treatment of this writer — its love of paradox and change, its dastard submission to prejudice and to the fashion of the day. Five-and-twenty years ago he was in the very zenith of a sultry and unwholesome popularity; he blazed as a sun in the firmament of reputation; no one was more talked of, more looked up to, more sought after, and wherever liberty, truth, justice was the theme, his name was not far off: — now he has sunk below the horizon, and enjoys the serene twilight of a doubtful immortality. Mr. Godwin, during his lifetime, has secured to himself the triumphs and the mortifications of an extreme notoriety and of a sort of posthumous fame. His bark, after being tossed in the revolutionary tempest, now raised to heaven by all the fury of popular breath, now almost dashed in pieces, and buried in the quicksands of ignorance, or scorched with the lightning of momentary indignation, at length floats on the calm wave that is to bear it down the stream of time.
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Hillerdal, Gunnar. "Health Problems Related to Environmental Fibrous Minerals." In Geology and Health. Oxford University Press, 2003. http://dx.doi.org/10.1093/oso/9780195162042.003.0025.
Повний текст джерелаАнотація:
Very early in the history of mining and with the industrial applications of asbestos, it was known that a variety of mineral fibers were hazardous to health. By the 1940s, the potential risk of lung cancer, in addition to the fibrosis disorder asbestosis, one of the pneumoconioses, was described. Within twenty years, another malignant disease, mesothelioma, cancer of the tissues that surround the lung, was ascribed to asbestos exposure. It is now common knowledge that inhalation of certain mineral fibers can cause disease (Skinner et al. 1988). Because the fibers are inhaled, the lung and surrounding tissues are the primary targets, but there may be subsequent reactions in many other parts of the body. The information on disease related to fibrous materials emanates from studies of occupational environments where the dose or exposure is likely to be high and continued over long periods of time. However, it has been increasingly realized that domestic or general environmental exposure is also possible and can pose grave dangers. For a mineral fiber to be inhalable it should be less than one micron in diameter, but the length can be 10 microns or greater because the particle can align with the air stream in the bronchi and penetrate far into the lung. The ratio between length and diameter of the fiber is critical. The most dangerous fibers are very thin (one tenth of a micron in diameter or less) with a high length-diameter ratio. Another important factor is biodurability. Typically, the dangerous fibers are not broken down at all or only very slowly, with half-lives in the body of many years. They may remain in situ throughout life and can be found at autopsy. There are many varieties of fibers in the environment today, both naturally occurring and man-made. Only a few, however, fulfill the above criteria and occur in amounts where human exposure is possible. The problem fibers are collectively known as asbestos and the fibrous zeolite, erionite. There are many other fibers (Skinner et al. 1988), but their contributions to human disease are not recognized. Asbestos is not a mineralogical but a commercial term.
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Rosell, Frank, and Róisín Campbell-Palmer. "Territoriality, communication, and populations." In Beavers, 221–60. Oxford University Press, 2022. http://dx.doi.org/10.1093/oso/9780198835042.003.0007.
Повний текст джерелаАнотація:
Beavers are highly territorial and actively defend a territory that includes nutritional resources, one or more rest sites, a family overwintering site, and a reproduction site. New territories are normally established during early autumn when dispersing subadults settle down in a new area of their own, but this can vary considerably. Each family group scent marks its territories with castoreum and/or anal gland secretion. Territory size is generally measured as the length of shoreline but can also be expressed as a combination of terrestrial and aquatic patches used by the beavers in a two-dimensional space. The territorial size depends on many factors such as habitat quality and quantity, habitat type (stream, river, or pond), density of beavers, social factors (sex and age), time of year (season), and settlement pattern. Beavers patrol their territory to look out for intruders and potential predators and scent mark their territory with fluid from their castor sacs and/or secretions from their anal glands. Territorial defence can include direct fighting or even more unusual warning behaviours such as boundary stick displays. The duration of territory occupancy and its importance for the fitness of beavers are also discussed. Further, this chapter explores beaver communication using odours, sounds, tail slapping, poses, and other movements. Beavers predominantly communicate via odours, but the importance of all these modalities is explored. Lastly, population estimations, growth, fluctuations, and densities of beaver populations are discussed.
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Worster, Donald. "Paths Across the Levee." In Wealth of Nature. Oxford University Press, 1994. http://dx.doi.org/10.1093/oso/9780195092646.003.0005.
Повний текст джерелаАнотація:
In 1821 a man came exploring across the prairies and plains of the North American continent. His name was Jacob Fowler, and with his companions he would be the first Euro-American to ascend the whole length of the Arkansas River from what is now Fort Smith, Arkansas, to the Rocky Mountains. After eight days of poling against the current, “we stoped,” he writes in his untutored spelling, “at the mouth of a bold sreem of Watter” emptying into the Arkansas, a tributary about seventy feet wide. They followed that stream north through the sand hills that cover part of present-day Reno and Rice counties in the state of Kansas. Only a few cottonwood trees grew along its banks, affording scant shelter from the big sky, but the bluestem grass was so high one could not see the river ahead as it meandered across the prairie. Beyond the rich moist bottomlands the vegetation became buffalo grass, and the bison grazed there in black, drifting multitudes; the local Indians called the stream after the female bison, a name that became “Cow Creek” in the white man’s tongue. There were pronghorn antelopes in those days, so light and agile, counterpointing the shaggy herds. Fowler and his crew might also have seen deer, elk, coyotes, and dense flocks of ducks and geese. Then, their curiosity satisfied and their senses pleased, they pushed on west. Fowler had no idea that almost three centuries earlier another European, Don Francisco Vásquez de Coronado, had come here from the opposite direction, crossing this very same Cow Creek on his quest for the fabled city of Quivira. Coronado found in the vicinity only the Wichita Indians living in domed huts thatched with grass, but he did remark that . . . the country itself is the best I have ever seen for producing all the products of Spain, for besides the land itself being very fat and black, and being very well watered by the rivulets and springs and rivers, I found prunes like those of Spain and nuts and very good sweet grapes and mulberries. . . .
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Bartlett, Howard. "Kindergarten, Again." In Learning Together. Oxford University Press, 2001. http://dx.doi.org/10.1093/oso/9780195097535.003.0026.
Повний текст джерелаАнотація:
Just because I was going back to kindergarten at the age of 42 was no reason to be nervous. After all, I had breezed through kindergarten 37 years earlier, or so my mother assured me with a warm smile as she leaned in the bathroom doorway watching me shave. “So you’re going co-oping,” my mother said. I stopped my razor at the end of its dull and somewhat painful passage up the length of my neck. I replied with a tentative yes. “What does a co-oper do?” My newly widowed mother had moved out of New England during the summer to help with the raising of our son, Bartie. She was a Yankee down to the depths of her crusty soul, suspicious, sure of what she knew, forever ready to take on the world with a mixture of honesty and determination that left little room for doubt that she would do her best to stick around forever to ensure that her own would have a safe passage through the world. “Co-opers help out in the classroom,” I replied, rinsing my razor under a brief stream of water. I knew that my reply was too short. My mother already should have known. My wife, Leslee, had been teaching in the OC for 10 years. I had written many letters home explaining the philosophy of placing the child at the center of the learning experience. “Help out? How do you help out?” Mother shifted restlessly in the doorway. I knew her well. She was concerned that this unusual school might not be good enough for her grandson. Questions she already knew the answers to were her own way of being nervous. Like all the first-time parents, she was letting a piece of herself go that morning. A school with no desks, no grades: How could she be sure that her grandson would get the basics? The idea of communication and understanding before competition sounds good. Childhood is a journey, not a race. That sounded good, too. But still... “We come up with learning centers or activities, or we help students problem solve when there is a dispute. Or we might go through stories children have just written and help them ‘book spell’ the words they spelled their own way.
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Bennett, Peggy D. "Valuing your voice." In Teaching with Vitality. Oxford University Press, 2017. http://dx.doi.org/10.1093/oso/9780190673987.003.0021.
Повний текст джерелаАнотація:
If you have ever contracted laryngitis, you know the value of your voice. You feel fine. You are not contagious. You have much to do. You cannot make a good argument for staying home. Yet teaching without a healthy voice can be hard, hard work. Our voice is our most precious instrument. Do we care for it as if that is true? These five suggestions can help you maintain a healthy voice. 1. Balance of breath and muscle. When vocal sound production is balanced with muscle and breath, we are generally using our voice properly. When more muscle than breath is used, a forced sound causes undue stress on our vocal folds, often resulting in a raspy sound. Support your voice with breath energy to help maintain healthy vocal production. 2. Hydration. Talking for lengthy amounts of time causes us to lose moisture through our breath. Don’t wait until you’re thirsty to drink water. Stay hydrated throughout the day. 3. Avoid touching your face. Our hands are often the germiest parts of our bodies. To maintain a healthy voice, avoid touching your face, especially during cold and flu season. 4. Vary your vocal expression. Variety in pitch, pace, and volume is good for our voices and good for our listeners. Vary the pitch of your voice by shifting between higher and lower tones. Speed up and slow down the pace of your speaking. Speak at louder and quieter volumes to help students listen. 5. Lift your voice. Speaking at the lower part of your vocal range, especially if you are projecting loudly to a group, can cause vocal difficulties similar to a callus on your vocal folds. For the health of your voice, lift it to a medium high range (say “mm- hm” as an agreement and stay at the “hm” level) and speak using plenty of breath energy. The louder we talk, the less students need or want to listen! Try speaking normally rather than “talking over” noisy students; they will learn to respond. In physical education, music ensembles, and other large classes, a habit of shout- speaking can develop and derail your vocal health.
Тези доповідей конференцій з теми "DOWN STREEM LENGHT"
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Yuan, Hai, Kazuma Kawano, Kazuyoshi Sekine, and Hiroaki Maruyama. "Investigation on Tendency of Stress in Local Thin Area of Shell Plate of Oil Storage Tank." In ASME 2006 Pressure Vessels and Piping/ICPVT-11 Conference. ASMEDC, 2006. http://dx.doi.org/10.1115/pvp2006-icpvt-11-93254.
Повний текст джерелаАнотація:
The shell plate of oil storage tank is an important evaluating component in the Fitness-For Service Assessment (FFS), because it is required to have sufficient strength against static and dynamic pressures in both operating and earthquake conditions. This paper presents an investigation on the tendency of stress occurred in the local thin areas (LTAs) of shell plate subjected to an internal pressure by using a partial three-dimensional shell model. In the analyses, a LTA is assumed as a rectangular area or a ring area with a rectangular cross section, and its lengths in the longitudinal and circumferential directions are taken as study parameters. The tendency of stress ratio (the stress in LTA of shell plate to that without LTA) has been investigated and the analytical results show that there is a tendency for stress ratio to be going up when the longitudinal length of LTA lengthens gradually and the thickness of shell plate is decreased. But it is opposite for increasing the circumferential length, when the stress ratio is going down. The relation between the stress ratio and the shape of LTA with different combination of sizes are clarified by the analytical results.
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Pervez, Tasneem, Omar S. Al-Abri, and Sayyad Z. Qamar. "Minimization of Pop-Out Phenomenon Effect in Down-Hole Tubular Expansion." In ASME 2015 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/imece2015-51653.
Повний текст джерелаАнотація:
In published literature, Solid Expandable Tubular (SET) is defined as a down-hole cold work process to expand a tubular to attain desired inner diameter. Tubular expansion process is a complicated process and a number of challenges are associated with its usage. However, proper planning before execution may lead the operators for more options that can affect important parameters such as; tubular length after expansion, hole diameter, expansion force, tubular structural integrity, post expansion properties, suitable material for tubular, selection or design of associated tools for expansion, and optimal selection of system components based on formation type, to name a few. Further studies are needed to overcome the challenges of these problems. Most of the published materials in this area mainly present the experience of using the technology without pointing directly to the technical challenges and understanding the fundamentals behind it. The successful expansion process shall make sure of no fracture, burst, collapse or any damage in the tubular; constant tubular diameter along the tubular; and the structural integrity of tubular and tubular connections. In general, expansion process involves placing a cone inside tubular and through the application of force at one end of the cone tubular expands. The sudden release of energy, at the end of expansion process, acts as a dynamic excitation to the tubular-fluid-formation system, which may affect tubular material properties and geometry, and is termed as pop-out phenomenon. The dynamics of problem is solved by considering inner/outer fluids and tubular itself. The forward and backward movement of pressure waves in inner and outer fluid and the stress wave in tubular is solved analytically as a coupled problem. It is assumed that the three mediums are uniform in nature, formation is isotropic, damping is negligible, fluid velocity behind cone is low and wave lengths are large compared to borehole diameter. It was found that the fluctuating stress levels at the fixed end of the tubular causes permanent ripples, which will increase tubular diameter beyond allowable limit and/or will cause converging and diverging sections within the tubular resulting from constructive or destructive interference of stress wave originating after pop-out. In order to limit the number of runs for computer simulation, particular type of tubular and well are chosen, hence keeping the geometrical parameters constant for all simulation. Other parameters are changed and their effects on pop-out phenomenon are determined. The results show that changing the formations, inner and outer fluid densities have no effect on the inner fluid pressure and axial stress for specific tubular materials. However, significant variations occur in outer fluid pressure. Among all tubular materials high Mn steel alloy experiences lower stress values. The current study can be used to aid in selection of reliable materials for SET system to minimize the affect of pop-out phenomenon. Also, formations variation varies outer fluid pressure. In addition, all expansion ratios follow the same pattern in parameters variation.
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Harvey, J., K. S. Narayanan, S. K. Das, E. V. H. M. Rao, G. Lydia, B. Malarvizhi, S. S. Murthy, M. Kumaresan, N. Kasinathan, and M. Rajan. "Assessment of Debris Bed Formation Characteristics Following Core Melt Down Scenario With Simulant System." In 16th International Conference on Nuclear Engineering. ASMEDC, 2008. http://dx.doi.org/10.1115/icone16-48172.
Повний текст джерелаАнотація:
In a fast reactor safety analysis determination of the molten core conditions when it reaches the core catcher plate is one of the main factors after a postulated MFCI event. If large fragmentation and quenching is accomplished in the coolant column no major problems for main vessel attack would occur. If instead, a significant amount of melt would remain as a solid molten cake, potential for lower head penetration would exist. In the present study towards development of a model for core melting and debris settling on to a core catcher plate, early phase of liquid stream fragmentation progression due to hydrodynamic consideration was investigated with woods metal melt water system. The system selected simulates the hydrodynamic physical properties more closely that of liquid UO2-sodium system. Assessment of debris-bed forming characteristics was carried out with different coolant column and different melt temperatures with melt inventories up to 20 kg released from a nozzle of 8 mm diameter. Bed height, debris spread area, jet break up length and repose angle obtained are presented for a melt release rate of ∼ 600 g/s. Only solidified debris constituted the bed for a melt temperature of 100°C and water temperature of 29 °C, with 720 mm water height. The estimated average bed height, bed porosity and heap repose angle were 15 cm, ∼0.6 and 43° respectively. Solidified central columnar lump of height 30 cm was seen for a water column of 360 mm. Relative bed forming characteristics for melt temperatures of 120 °C and 220 °C are also presented. High speed video imaging was taken to assess the stream break up distance and heap formation dynamics. Bulk coolant temperatures close to the melt stream were also monitored. Dependence of particulate debris and bed characteristics on melt temperature, interaction height and melt inventory have been brought out.
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Hong, Jeong K., and Thomas P. Forte. "Study on Weld Fatigue Evaluation Under Sour Service Environment Using Battelle Structural Stress Method." In ASME 2013 32nd International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/omae2013-10374.
Повний текст джерелаАнотація:
Risers, pipelines and flowlines for deep water applications are subject to corrosive environments. Especially, in the presence of hydrogen sulfide which makes the field sour, their fatigue performance becomes significantly degraded. In order to quantify the sour degradation effect, a knock-down factor has been introduced. This factor is defined as the fatigue life reduction relative to the in-air fatigue life. Several sets of fatigue test results in sour service environments have been published. These include strip specimens of different sizes, e.g., diameters, wall thicknesses, and arc lengths. Naturally, the knock-down factor must be based upon a statistically valid number of fatigue test results obtained from the same specimen geometry and the same loading conditions tested in air and in sour conditions. Currently, the database available in the open literature is too limited to properly define a knock-down factor. Moreover, there is a great deal of scatter within the database and each test in a sour environment is costly and time consuming. Thus, it is difficult to establish a statistically valid database upon which to base the knock-down factor. A mesh-insensitive structural stress method has been developed by Battelle researchers and has been proven to be highly effective in correlating the fatigue behavior of welded joints. In 2007, the Battelle structural stress based weld fatigue master S-N curve was included in ASME Section VIII Div. 2 because it successfully consolidated more than 800 fatigue test results for weld toe failures onto a single master S-N curve with very little scatter, regardless of specimen shape, size, loading type, and steel alloy [1–2]. A knock-down factor is derived by applying the Battelle structural stress method to the existing database for sour environment tests and by using the current in-air database as the reference condition. This approach will reduce the uncertainty in the knock-down factor because it allows a wider range of sour environment data from specimens of different sizes, types, and loading conditions to be combined, while simultaneously reducing scatter. As such, a unified knock-down factor can be determined with greater statistical validity and wider applicability for design recommendations in sour conditions.
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Ðurović, Kristina, Luca De Vincentiis, Daniele Simoni, Davide Lengani, Jan Pralits, Dan S. Henningson, and Ardeshir Hanifi. "Free-Stream Turbulence Induced Boundary-Layer Transition in Low-Pressure Turbines." In ASME Turbo Expo 2020: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/gt2020-15808.
Повний текст джерелаАнотація:
Abstract The aerodynamic efficiency of turbomachinery blades is profoundly affected by the occurrence of laminar-turbulent transition in the boundary layer since skin friction and losses rise for the turbulent state. Depending on the free-stream turbulence level, we can identify different paths towards a turbulent state. The present study uses direct numerical simulation as the primary tool to investigate the flow behaviour of the low-pressure turbine blade. The computational set-up was designed to follow the experiments by Lengani & Simoni [1]. In the simulations, the flow past only one blade is computed, with periodic boundary conditions in the cross-flow directions to account for the cascade. Isotropic homogeneous free-stream turbulence is prescribed at the inlet. The free-stream turbulence is prescribed as a superposition of Fourier modes with a random phase shift. Two levels of the free-stream turbulence intensity were simulated (Tu = 0.19% and 5.2%), with the integral length scale being 0.167c, at the leading edge. We observed that in case of low free-stream turbulence on the suction side, the Kelvin–Helmholz instability dominated the transition process and full-span vortices were shed from the separation bubble. Transition on the suction side proceeded more rapidly in the high-turbulence case, where streaks broke down into turbulent spots and caused bypass transition. On the pressure side, we have identified the appearance of longitudinal vortical structures, where increasing the turbulence level gives rise to more longitudinal structures. We note that these vortical structures are not produced by Görtler instability.
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Kim, Gap-Yong, Muammer Koc, and Jun Ni. "Modeling of Size Effects on the Flow Stress of Type 304 Stainless Steel and Application in Coining Process." In ASME 2007 International Mechanical Engineering Congress and Exposition. ASMEDC, 2007. http://dx.doi.org/10.1115/imece2007-41971.
Повний текст джерелаАнотація:
Application of microforming in various research areas has received much attention due to the increased demand for miniature metallic parts that require mass production. For the accurate analysis and design of microforming process, proper modeling of material behavior at the micro/meso-scale is necessary by considering the size effects. Two size effects are known to exist in metallic materials. One is the “grain size” effect, and the other is the “feature/specimen size” effect. This study investigated the “feature/specimen size” effect and introduced a scaling model which combined both feature/specimen and grain size effects. Predicted size effects were compared with experiments obtained from previous research and showed a very good agreement. The model was also applied to forming of micro-features by coining. A flow stress model for Type 304 stainless steel taking into consideration the effect of the grain and feature size was developed and implemented into a finite element simulation tool for an accurate numerical analysis. The scaling model offered a simple way to model the size effect down to length scales of a couple of grains and extended the use of continuum plasticity theories to micro/meso-length scales.
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Spanner, Jack, and Greg Selby. "Sizing Stress Corrosion Cracking in Natural Gas Pipelines Using Phased Array Ultrasound." In ASME 2002 Pressure Vessels and Piping Conference. ASMEDC, 2002. http://dx.doi.org/10.1115/pvp2002-1637.
Повний текст джерелаАнотація:
Gas transmission pipelines are inspected periodically by robotic systems that pass through the pipe. These inspection systems typically use electromagnetic nondestructive evaluation (NDE) techniques to detect flaws such as stress corrosion cracking (SCC). The electromagnetic techniques can detect and measure the length of the cracks, but cannot measure through wall depths. In some cases it would be desirable to excavate down to a cracked area of the pipe, inspect it “in the ditch” to determine the depth of the cracking, and use the depth information to support repair/replacement decisions. The objective of the research was to develop a nondestructive inspection technique capable of measuring the depth of stress corrosion cracks from the outside surface of a gas transmission pipe in the field. EPRI participated in the round robin study by using a linear phased array technique. Field removed specimens were provided by the Gas Technology Institute (GTI) containing SCC for depth sizing. In most cases sizing was difficult to accomplish because of the colony of cracks that existed. This presentation discusses the results obtained and comparing them to destructive analysis results.
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Kobrinsky, Mauro J., Erik R. Deutsch, and Stephen D. Senturia. "Influence of Support Compliance and Residual Stress on the Shape of Doubly-Supported Surface-Micromachined Beams." In ASME 1999 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1999. http://dx.doi.org/10.1115/imece1999-0238.
Повний текст джерелаАнотація:
Abstract Doubly-supported surface-micromachined beams are increasingly used to study the mechanical properties of thin films. Residual stresses in the beams cause significant vertical deflections, which affect the performance of these devices. We present here both experimental results for doubly-supported polysilicon surface-micromachined beams, and an elastic model of the devices that takes into account the compliance of the supports and the geometrical non-linear dependence of the vertical deflections on the stress in the beam. An elastic one-dimensional model was used for the beams, and the response of the supports to forces and moments was obtained using Finite Element Method simulations. The model explains a previously observed gradual increase of the maximum vertical deflections of the beams with increasing length at a given constant residual stress, and, in agreement with experimental observations, predicts two stable states for compressively stressed beams: one with the beam bent up, the other down.
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Yin, Shengjun, Terry L. Dickson, Paul T. Williams, and B. Richard Bass. "Stress Intensity Factor Influence Coefficients for External Surface Flaws in Boiling Water Reactor Pressure Vessels." In ASME 2009 Pressure Vessels and Piping Conference. ASMEDC, 2009. http://dx.doi.org/10.1115/pvp2009-77143.
Повний текст джерелаАнотація:
Over the service life of a nuclear power plant, the Boiling Water Reactor (BWR) may undergo many cool-down and heat-up thermal-hydraulic transients associated with, for example, scheduled refueling outages and other normal operational transients, or even possible overcooling transients. These thermal-hydraulic events can act on postulated surface flaws in BWRs and therefore impose potential risk on the structure integrity of Reactor Pressure Vessels (RPVs). Internal surface flaws are of interest for the BWRs under overcooling accidental scenarios, while external surface flaws are more vulnerable when the BWRs are subjected to heat-up transients. Stress Intensity Factor Influence Coefficient (SIFIC) databases for application to linear elastic fracture mechanics analyses of BWR pressure vessels which typically have an internal radius to wall thickness ratio (Ri/t) between 15 and 20 were developed for external surface breaking flaws. This paper presents three types of surface flaws necessary in fracture analyses of BWRs: (1) finite-length external surface flaws with aspect ratio of 2, 6, and 10. (2) infinite-length axial external surface flaws; and (3) 360° circumferential external surface flaws. These influence coefficients have been implemented and validated in the FAVOR fracture mechanics code developed at Oak Ridge National Laboratory (ORNL) for the US Nuclear Regulatory Commission (NRC). Although these SIFIC databases were developed in application to RPVs subjected to thermal-hydraulic transients, they could also be applied to RPVs under other general loading conditions.
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Key, M. H., C. Brown, R. G. Evans, P. Gott-Feldt, C. J. Hooker, D. Peler, S. J. Rose, et al. "XUV laser action in recombining laser-produced plasmas." In OSA Annual Meeting. Washington, D.C.: Optica Publishing Group, 1986. http://dx.doi.org/10.1364/oam.1986.wp2.
Повний текст джерелаАнотація:
New facilities for XUV laser research have recently been brought into operation at the SERC Rutherford Appleton Laboratory in the U.K. The new apparatus provides irradiation of targets at power levels of more than 1 TW in line focus geometry with length up to 2 cm and width down to 25 μm. In addition new subnanosecond time-resolved XUV diagnostics have been developed using streak cameras coupled to aperiodic grazing incidence diffraction gratings, producing a dispersed spectrum in a flat field. A consortium of U.K. research groups has been using the new facilities to study and develop XUV lasers based on recombination.
Звіти організацій з теми "DOWN STREEM LENGHT"
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Jacobsen, Nils. Linjebussens vekst og fall i den voksende byen: en studie av bybussenes geografiske kvalitet Stavanger – Sandnes 1920 – 2010. University of Stavanger, November 2019. http://dx.doi.org/10.31265/usps.244.
Повний текст джерелаАнотація:
Linear city bus services are facing increased challenges from city growth. Increased number of inhabitants on increasing acres of built-up areas, makes it demanding to maintain adequate bus services within reasonable catchment areas. Number of departures per hour give a partial description of the bus service quality. Number of departures give reference to the time aspect of bus service quality, but say nothing about the geographical aspect. What part of the entire line network is within reach of direct bus service when frequencies are limited? To address the geographical aspect of bus service quality, the term network ratio is introduced. The term Network Ratio (NR) signifies what part of the entire line network is within reach of direct bus service to or from a certain place in the network. Network Ratio is given as a mathematical term whereby direct bus lines are calculated as a percentage of the entire network. The character and development of Network Ratio in a specific city is illustrated through an analysis of the urban growth of line network and built-up areas in the twin cities of Stavanger and Sandnes. The analysis is covering the period 1920 – 2000 in intervals of 20 years from the first bus lines were established in the urban area. Year 2010 is also included due to major changes implemented right after the turn of the millennium. Development show there is a close relation between bus network and built-up areas. When areas are being built, bus lines follow. The initial fase 1920 – 40 with extensive development of bus lines combined with some areal growth, is followed by a fase of consolidation 1940 – 60. The latter period is characterized by moderate areal growth, extended lines reducing network ratios, and increasing frequencies on the best bus lines. Extensive areal growth in the following period 1960 – 80, implies increased number of bus lines. As a consequence network ratios as well as frequencies are falling in the entire network. In 1960 certain lines had developed as much as 6 departures per hour, while maximum bus line frequency in 1980 has diminished to 2. New bus service development is introduced in the following period between 1980 and 2000. Numerous bus companies are united, and a more comprehensive planning of bus services are applied. The number of bus lines is stabilized at about 40, the fall in network ratio is reduced, and certain lines develop 4 departures per hour. Parallell to the bus development, growth of built-up areas is slowing down due to increased urban renewal with higher densities within built-up areas. In the period 2000 – 2010 new efforts are given to the development of bus services. Development of Network Ratio takes a new direction: The length of network links with high NR is increasing, while links with very low NR are diminishing. Number of bus lines is decreasing, and by 2010 almost 50% of the bus lines are served with 4 departures or more. Passenger comfort is improved in buses as well as on bus stops, and low floor buses are introduced to ease accessibility. Bus service quality is further developed after 2010. Digital services are introduced including digital ticketing, bus service information and real-time information on internet. In addition real-time information is presented at high frequency bus stops through visual screen and auditory speaker. Inside the buses name of next stop is given on screen and through loudspeaker. Further development of the bus services, should include improved Network Ratios in the entire network, as well as increased frequencies on major bus corridors. The latter is a task not only for the bus service planners, but just as well for the city planners and politicians in collaboration with the developers implementing urban density and allocation of important destinations. A last, but not least, objective for bus service development will be to improve punctuality and total travel time. Today a considerable proportion of city bus services are delayed in car traffic congestions. This is occurring especially on main streets and during rush hours. A set of different solutions are needed to address this question: 1. Dedicated bus streets (including car access to limited addresses) 2. Bus lines through local streets in concentrated housing, office and shopping areas. 3. Dedicated bus lane on main streets where possible. 4. Car traffic regulations on main streets without space for extra bus lane. As an overall vision, we need to cultivate the word of Flemming Larsen: urban growth as pearls on a string, as shown in fig. 13 and fig. 14.