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Li, Xin Li. "Optimal Energy Management Strategy for Parallel Scheduling." Applied Mechanics and Materials 568-570 (June 2014): 1539–46. http://dx.doi.org/10.4028/www.scientific.net/amm.568-570.1539.
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Large-scale data streams processing is now fundamental to many data processing applications. There is growing focus on manipulating Large-scale data streams on GPUs in order to improve the data throughput. Hence, there is a need to investigate the parallel scheduling strategy at the task level for the Large-scale data streamsprocessing, and to support them efficiently. We propose two different parallel scheduling strategies to handle massive data streamsin real time. Additionally, massive data streamsprocessing on GPUs is energy-consumed computation task. So we consider the power efficiency as an important factor to the parallel strategies. We present an approximation method to quantify the power efficiency for massive data streams during the computing phase. Finally, we test and compare the two parallel scheduling strategies on a large quantity of synthetic and real stream datas. The simulation experiments and compuatation results in practice both prove the accuracy of analysis on performance and power efficiency.
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Mrzljak, Vedran, Jasna Prpić-Oršić, and Tomislav Senčić. "Change in Steam Generators Main and Auxiliary Energy Flow Streams During the Load Increase of LNG Carrier Steam Propulsion System." Pomorstvo 32, no. 1 (June 20, 2018): 121–31. http://dx.doi.org/10.31217/p.32.1.15.
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In this paper is presented an analysis of main and auxiliary steam energy flow streams from steam generators during the increase in steam system load at conventional LNG carrier. During the steam system load increase was presented differences in steam pressure and temperature between main and auxiliary steam flow streams. Energy power of the auxiliary flow stream is higher than energy power of the main flow stream only at the lowest steam system loads after which main flow stream takes over primacy at middle and high steam system loads. Cumulative auxiliary energy flow stream was divided on energy flow streams to each auxiliary device and energy power consumption of each auxiliary device was also investigated throughout number steam system loads. Analysis of steam production from marine steam generators presented in this paper provides insight into the operation dynamics of the entire steam propulsion system.
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Miller, L. M., F. Gans, and A. Kleidon. "Jet stream wind power as a renewable energy resource: little power, big impacts." Earth System Dynamics 2, no. 2 (November 29, 2011): 201–12. http://dx.doi.org/10.5194/esd-2-201-2011.
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Abstract. Jet streams are regions of sustained high wind speeds in the upper atmosphere and are seen by some as a substantial renewable energy resource. However, jet streams are nearly geostrophic flow, that is, they result from the balance between the pressure gradient and Coriolis force in the near absence of friction. Therefore, jet stream motion is associated with very small generation rates of kinetic energy to maintain the high wind velocities, and it is this generation rate that will ultimately limit the potential use of jet streams as a renewable energy resource. Here we estimate the maximum limit of jet stream wind power by considering extraction of kinetic energy as a term in the free energy balance of kinetic energy that describes the generation, depletion, and extraction of kinetic energy. We use this balance as the basis to quantify the maximum limit of how much kinetic energy can be extracted sustainably from the jet streams of the global atmosphere as well as the potential climatic impacts of its use. We first use a simple thought experiment of geostrophic flow to demonstrate why the high wind velocities of the jet streams are not associated with a high potential for renewable energy generation. We then use an atmospheric general circulation model to estimate that the maximum sustainable extraction from jet streams of the global atmosphere is about 7.5 TW. This estimate is about 200-times less than previous estimates and is due to the fact that the common expression for instantaneous wind power 12 ρv3 merely characterizes the transport of kinetic energy by the flow, but not the generation rate of kinetic energy. We also find that when maximum wind power is extracted from the jet streams, it results in significant climatic impacts due to a substantial increase of heat transport across the jet streams in the upper atmosphere. This results in upper atmospheric temperature differences of >20 °C, greater atmospheric stability, substantial reduction in synoptic activity, and substantial differences in surface climate. We conclude that jet stream wind power does not have the potential to become a significant source of renewable energy.
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Miller, L. M., F. Gans, and A. Kleidon. "Jet stream wind power as a renewable energy resource: little power, big impacts." Earth System Dynamics Discussions 2, no. 1 (June 17, 2011): 435–65. http://dx.doi.org/10.5194/esdd-2-435-2011.
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Abstract. Jet streams are regions of sustained high wind speeds in the upper atmosphere and are seen by some as a substantial renewable energy resource. However, jet streams are nearly geostrophic flow, that is, they result from the balance between the pressure gradient and Coriolis force in the near absence of friction. Therefore, jet stream motion is associated with very small generation rates of kinetic energy to maintain the high wind velocities, and it is this generation rate that will ultimately limit the potential use of jet streams as a renewable energy resource. Here we estimate the maximum limit of jet stream wind power by considering extraction of kinetic energy as a term in the free energy balance of kinetic energy that describes the generation, depletion, and extraction of kinetic energy. We use this balance as the basis to quantify the maximum limit of how much kinetic energy can be extracted sustainably from the jet streams of the global atmosphere as well as the potential climatic impacts of its use. We first use a simple thought experiment of geostrophic flow to demonstrate why the high wind velocities of the jet streams are not associated with a high potential for renewable energy generation. We then use an atmospheric general circulation model to estimate that the maximum sustainable extraction from jet streams of the global atmosphere is about 7.5 TW. This estimate is about 200-times less than previous estimates and is due to the fact that the common expression for instantaneous wind power &frac12 ρ v3 merely characterizes the transport of kinetic energy by the flow, but not the generation rate of kinetic energy. We also find that when maximum wind power is extracted from the jet streams, it results in significant climatic impacts due to a substantial increase of heat transport across the jet streams in the upper atmosphere. This results in upper atmospheric temperature differences of >20 °C, greater atmospheric stability, substantial reduction in synoptic activity, and substantial differences in surface climate. We conclude that jet stream wind power does not have the potential to become a significant source of renewable energy.
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Raymond, C. F. "Energy balance of ice streams." Journal of Glaciology 46, no. 155 (2000): 665–74. http://dx.doi.org/10.3189/172756500781832701.
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AbstractAnalysis of the cross-flow transmission of force from the central parts of a well-lubricated ice stream to its margins shows that there is a corresponding shift in the lateral location of motion-induced heat generation. The rate of basal heat generation in the center can be substantially smaller than the local rate of potential energy loss given by driving stress times the speed of downslope motion. The basal heating is a maximum for an intermediate level of lubrication for which speed is about 40% of the speed over a friction-less bed and base stress is about 25% of the driving stress. Stable and unstable balances between meltwater production and drainage on the bed are identified. A stable steady state with a speed less (more) than that giving maximum heat generation is termed drainage-(production-) limited, since an increase in speed would lead to increased (decreased) basal melting and must (need not) be balanced by increased drainage. It is shown that gradual evolution of the basal water drainage system and the factors affecting basal melting can cause discontinuous jumps between fast- and slow-moving states. A simplified analysis applied to six cross-sections of West Antarctic Ice Streams B, D, E and Rutford Ice Stream shows them to be diverse in the level of support from the sides and corresponding shift of mechanical heating sideward from their central parts. The cross-sections of Ice Stream B near “Upstream B” may be production-limited, because of especially high lubrication and related support from the sides. Cross-sections in the upper part of Ice Stream D, Ice Stream E and Rutford Ice Stream are in a drainage-limited condition. Substantial reduction of basal heat generation by side drag (in most cases) and expected high heat flow into the basal ice associated with low thickness (in some cases) tends to favor basal freezing. Nevertheless, all of the examined cross-sections except one are expected to experience basal melting with a modest geothermal heat-flux density of 60 m W m−1 or less in some cases. The lower part of Ice Stream B is an exception, where the analysis indicates that geothermal flux density must exceed 80–100 m W−1 m to maintain melting. If this high geothermal flux is not present, then the base of the lower part of Ice Stream B may be freezing, which would suggest continued deceleration of this part of Ice Stream B.
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Perry, Russell W., Michael J. Bradford, and Jeffrey A. Grout. "Effects of disturbance on contribution of energy sources to growth of juvenile chinook salmon (Oncorhynchus tshawytscha) in boreal streams." Canadian Journal of Fisheries and Aquatic Sciences 60, no. 4 (April 1, 2003): 390–400. http://dx.doi.org/10.1139/f03-035.
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We used stable isotopes of carbon in a growth-dependent tissue-turnover model to quantify the relative contribution of autochthonous and terrestrial energy sources to juvenile chinook salmon (Oncorhynchus tshawytscha) in five small boreal streams tributary to the upper Yukon River. We used a tissue-turnover model because fish did not grow enough to come into isotopic equilibrium with their diet. In two streams, autochthonous energy sources contributed 23 and 41% to the growth of juvenile salmon. In the other three, fish growth was largely due to terrestrial (i.e., allochthonous) energy sources. This low contribution of autochthonous energy appeared to be related to stream-specific disturbances: a recent forest fire impacted two of the streams and the third was affected by a large midsummer spate during the study. These disturbances reduced the relative abundance of herbivorous macroinvertebrates, the contribution of autochthonous material to other invertebrates, and ultimately, the energy flow between stream algae and fish. Our findings suggest that disturbances to streams can be an important mechanism affecting transfer of primary energy sources to higher trophic levels.
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Macayeal, D. R., R. A. Bindschadler, S. Shabtaie, S. Stephenson, and C. R. Bentley. "Force, Mass, and Energy Budgets of the Crary Ice Rise Complex, Antarctica." Journal of Glaciology 33, no. 114 (1987): 218–30. http://dx.doi.org/10.1017/s0022143000008728.
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AbstractResistive force exerted by the Crary Ice Rise on its ice-shelf/ice-stream environment and back-pressure force transmitted across the grounding lines of Ice Streams A and B are calculated from airborne radio echo-sounding data and measurements of surface strain-rates. Resistance generated by the ice rise ranges in magnitude between 45 and 51% of the back-pressure force on the ice streams (depending on the flow law). The mechanical-energy budget of the ice rise is computed by considering work done against frictional forces at the perimeter of the ice rise and gravitational potential energy fluxes associated with changing mass distribution in the ice/ocean system. Energy dissipated by flow surrounding the ice rise is balanced by potential energy released within Ice Streams A and B, and accounts for between 15 and 49% of the work done by the ice streams against ice-shelf back pressure at their grounding lines. Mass balance of the ice rise, and the discharge of Ice Streams A and B, are calculated from surface-velocity and snow-accumulation measurements. The ice rise and its immediate environment gain mass by advection and snowfall at a rate equivalent to an area-averaged thickening rate of 0.44 ± 0.06 m/year. This mass gain may be balanced by regional basal melting (which we do not measure), or could contribute to ice-rise expansion through regional thickening and ice-shelf grounding. Approximately 1/4 to 1/2 of the excess volume discharged by Ice Streams A and B above snow accumulation in their catchment areas is deposited in the vicinity of the ice rise (or melted from the bottom of the ice shelf). This suggests that the ice rise may have formed as a consequence of recent ice-stream acceleration, and that its continued growth may eventually reverse this trend of ice-stream discharge.
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Macayeal, D. R., R. A. Bindschadler, S. Shabtaie, S. Stephenson, and C. R. Bentley. "Force, Mass, and Energy Budgets of the Crary Ice Rise Complex, Antarctica." Journal of Glaciology 33, no. 114 (1987): 218–30. http://dx.doi.org/10.3189/s0022143000008728.
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AbstractResistive force exerted by the Crary Ice Rise on its ice-shelf/ice-stream environment and back-pressure force transmitted across the grounding lines of Ice Streams A and B are calculated from airborne radio echo-sounding data and measurements of surface strain-rates. Resistance generated by the ice rise ranges in magnitude between 45 and 51% of the back-pressure force on the ice streams (depending on the flow law). The mechanical-energy budget of the ice rise is computed by considering work done against frictional forces at the perimeter of the ice rise and gravitational potential energy fluxes associated with changing mass distribution in the ice/ocean system. Energy dissipated by flow surrounding the ice rise is balanced by potential energy released within Ice Streams A and B, and accounts for between 15 and 49% of the work done by the ice streams against ice-shelf back pressure at their grounding lines. Mass balance of the ice rise, and the discharge of Ice Streams A and B, are calculated from surface-velocity and snow-accumulation measurements. The ice rise and its immediate environment gain mass by advection and snowfall at a rate equivalent to an area-averaged thickening rate of 0.44 ± 0.06 m/year. This mass gain may be balanced by regional basal melting (which we do not measure), or could contribute to ice-rise expansion through regional thickening and ice-shelf grounding. Approximately 1/4 to 1/2 of the excess volume discharged by Ice Streams A and B above snow accumulation in their catchment areas is deposited in the vicinity of the ice rise (or melted from the bottom of the ice shelf). This suggests that the ice rise may have formed as a consequence of recent ice-stream acceleration, and that its continued growth may eventually reverse this trend of ice-stream discharge.
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Madinger, Hilary L., and Robert O. Hall Jr. "Nitrogen fluxes in Western streams." UW National Parks Service Research Station Annual Reports 40 (December 15, 2017): 61–68. http://dx.doi.org/10.13001/uwnpsrc.2017.5575.
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Nitrogen pollution to streams is altering the nitrogen cycling in unknown ways, causing challenges for predicting nitrogen fixation fluxes within aquatic ecosystems. Increasing nitrate pollution decreases the amount of nitrogen fixation occurring in streams. However, the relationship between stream nitrate concentration and the rate of nitrogen fixation is unknown. We predict that lower nitrate streams will have the highest rates of nitrogen fixation. Additionally, there will be much more energy produced in streams with nitrogen fixation compared to the amount required to fix the nitrogen. We estimated whole-stream gross primary production and nitrogen fixation fluxes using the diel change in dissolved nitrogen and oxygen gases compared to the expected dissolved gas saturation. Our whole-stream method is preferable to chamber estimates to understand the relationship between energy requirements for nitrogen fixation and gross primary production, but additional data is needed to distinguish between relationship types and make our measurements generalizable.
Featured photo by Intermountain Forest Service, USDA Region 4 Photography on Flickr. https://flic.kr/p/jbTRUj
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Mandelker, Nir, Daisuke Nagai, Han Aung, Avishai Dekel, Yuval Birnboim, and Frank C. van den Bosch. "Instability of supersonic cold streams feeding galaxies – IV. Survival of radiatively cooling streams." Monthly Notices of the Royal Astronomical Society 494, no. 2 (April 2, 2020): 2641–63. http://dx.doi.org/10.1093/mnras/staa812.
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ABSTRACT We study the effects of Kelvin–Helmholtz Instability (KHI) on the cold streams that feed massive haloes at high redshift, generalizing our earlier results to include the effects of radiative cooling and heating from a UV background, using analytic models and high resolution idealized simulations. We currently do not consider self-shielding, thermal conduction, or gravity. A key parameter in determining the fate of the streams is the ratio of the cooling time in the turbulent mixing layer which forms between the stream and the background following the onset of the instability, $t_{\rm cool,\, mix}$, to the time in which the mixing layer expands to the width of the stream in the non-radiative case, tshear. This can be converted into a critical stream radius, Rs, crit, such that $R_{\rm s}/R_{\rm s,crit}=t_{\rm shear}/t_{\rm cool,\, mix}$. If Rs < Rs, crit, the non-linear evolution proceeds similarly to the non-radiative case studied by Mandelker et al. If Rs > Rs,crit, which we find to almost always be the case for astrophysical cold streams, the stream is not disrupted by KHI. Rather, background mass cools and condenses on to the stream, and can increase the mass of cold gas by a factor of ∼3 within 10 stream sound crossing times. The mass entrainment induces thermal energy losses from the background and kinetic energy losses from the stream, which we model analytically. Roughly half of the dissipated energy is radiated away from gas with $T \lt 5\times 10^4\, {\rm K}$, suggesting much of it will be emitted in Ly α.
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Eckert, E. R. G. "Energy separation in fluid streams." International Communications in Heat and Mass Transfer 13, no. 2 (March 1986): 127–43. http://dx.doi.org/10.1016/0735-1933(86)90053-9.
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Chen, Jiaxing, Guomin Cui, Mei Cao, Heri Kayange, and Jian Li. "Heat Exchanger Network Optimization Based on the Participatory Evolution Strategy for Streams." Energies 14, no. 24 (December 13, 2021): 8392. http://dx.doi.org/10.3390/en14248392.
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The non-structural model of a heat exchanger network randomly selects a position of a node on hot and cold streams to generate a heat exchanger and an existing heat exchanger to participate in the evolution. Despite the model being more random and flexible, this selection method cannot easily find a good solution. In addition, the heat exchangers participating in the evolution might not be involved in all streams in each evolutionary process. A stream that does not participate in the evolution will have no significance to the current iteration. Therefore, many iterations are required to make each stream participate in the evolution, which limits the evolution efficiency of the optimization algorithm. In view of this shortcoming, this study proposes a participatory evolutionary strategy for streams based on hot streams. The proposed strategy reorders the existing heat exchangers on hot and cold streams and takes the corresponding measures to ensure that a heat exchanger is selected for each stream to participate in the evolution in every cycle. The proposed participatory evolutionary strategy for streams improves the global optimal solution for designs based on non-structural models. The effectiveness of the proposed strategy is demonstrated in two cases.
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Keeley, Ernest R., Steven O. Campbell, and Andre E. Kohler. "Bioenergetic calculations evaluate changes to habitat quality for salmonid fishes in streams treated with salmon carcass analog." Canadian Journal of Fisheries and Aquatic Sciences 73, no. 5 (May 2016): 819–31. http://dx.doi.org/10.1139/cjfas-2015-0265.
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Nutrient supplementation in oligotrophic streams is proposed as a means of mitigating losses of marine-derived subsidies from declining or extirpated populations of anadromous fishes. One of the central predictions of nutrient addition is an increased production of fish through bottom-up increases in invertebrate abundance. Such changes in food availability may increase growth and production rates for stream fishes by increasing habitat quality. In this study we apply bioenergetic calculations to estimate changes to habitat quality based on predicted increases in net energy intake. We compared invertebrate drift abundance and estimated changes in energy availability in streams treated with salmon carcass analog versus untreated controls. Our results revealed a two- to threefold increase in invertebrate drift abundance following the addition of salmon carcass analog; however, this effect appeared to be short-term. Measures of the energetic profitability of stream habitat for salmonid fishes revealed small, yet significant, increases in net energy availability in streams that received analog additions, but only after controlling for differences in physical habitat features such as temperature and stream flow.
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Kwon, Youngsang, Youkang Seo, and Jihyun Hwang. "Is the High-Density Housing Layout Affected by River Direction? Lessons from Seoul, South Korea." Sustainability 11, no. 11 (May 28, 2019): 3013. http://dx.doi.org/10.3390/su11113013.
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This study analyzes apartment building configurations in waterfront residential areas relative to water flow direction and assesses the waterfront impact on apartment construction planning. It surveyed 197 apartment buildings around Yangjaecheon, Gulpocheon, and Anyangcheon, three branches of the Han River, a major South Korean river, to ascertain the correlation between stream flows and apartment building configurations. The apartments were classified into four spatial-configuration categories relative to the adjacent stream’s flow axis—perpendicular, parallel, diagonal, and other—and three orientation categories—east- and/or west-facing, south-facing, and other. South-facing apartments were predominant around west- and north-flowing streams. The proportion of east- and/or west-facing apartments built and the percentage of south-facing apartments were relatively low, indicating that apartment building layouts are more diverse around north-flowing streams than around west-flowing streams. A t-test analysis of east- and south-facing apartments’ proportions relative to stream flow direction was statistically significant, and there were relatively higher percentages of east- and west-facing apartments near north-flowing streams than west-flowing ones. This suggests that the relationship with rivers is still important in urban housing in South Korea, and the importance of landscapes over the river is of increasing significance for planning urban settlements.
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Kobayashi, Sohei, Takashi Gomi, Roy C. Sidle, and Yasuhiro Takemon. "Disturbances structuring macroinvertebrate communities in steep headwater streams: relative importance of forest clearcutting and debris flow occurrence." Canadian Journal of Fisheries and Aquatic Sciences 67, no. 2 (February 2010): 427–44. http://dx.doi.org/10.1139/f09-186.
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This study shows that debris flow disturbances that alter in-channel physical conditions or displace organisms exert greater impacts on stream macroinvertebrate community structure than clearcutting disturbances that change energy inputs in steep headwater systems. We surveyed abiotic characteristics and macroinvertebrate communities of 10 steep headwater streams in central Japan that contained a chronosequence of forest stands and debris flow occurrences. Streams of recently logged forests had higher light levels, nitrate concentrations, and stream temperature ranges than streams of mature forests. Streams of middle-aged forests, which experienced debris flows in recent years (1989–1998), had lower abundance of shredders, crawlers, and headwater-adapted taxa than the other streams. A shredder taxon, Gammarus nipponensis , was completely absent in the streams with recent debris flows, despite their dominance in the other streams. Decreases of depositional environment associated with depletion of large wood and loss of channel structure as well as replacement of community members by rapid colonizers appear to be the major mechanisms of structural changes in macroinvertebrate communities affected by debris flows.
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Djail, Boubekeur, Walid Khaled Hidouci, and Malik Loudini. "A filtering technique for n-way stream joins in wireless sensors networks." Law, State and Telecommunications Review 11, no. 1 (May 20, 2019): 119–32. http://dx.doi.org/10.26512/lstr.v11i1.24853.
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Purpose – The join operations between data streams need more time and request more energy than traditional joins. In wireless sensor networks, energy is a critical factor. The survival of the network depends on this energy, thus it is necessary to consider, for this type of queries in such networks, the reduction of the sensors’ energy consumption. While works that have been done to treat n-way join operations between data streams are rare so far, we propose a technique, named NSLSJ (N-way Stream Local Semi-Join) to perform this type of join operations. The principal aim is to considerably reduce the consumed energy.
Methodology/approach/design – The technique 'N-way Stream Local Semi-Join (NSLSJ) proposed in this paper is based on an in-network execution, and on filtering tuples strategy for an important gain in energy.
Findings – Compared to NSLJ and Sens-Join techniques, NSLSJ shows better performances in the realized tests as it consumes less energy.
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Aidarov, K., P. Ezhilchelvan, and I. Mitrani. "Energy-aware Management of Customer Streams." Electronic Notes in Theoretical Computer Science 296 (August 2013): 199–210. http://dx.doi.org/10.1016/j.entcs.2013.07.013.
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Mesarina, Malena, and Yoshio Turner. "Reduced energy decoding of MPEG streams." Multimedia Systems 9, no. 2 (August 1, 2003): 202–13. http://dx.doi.org/10.1007/s00530-003-0090-7.
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Adcock, Thomas A. A., Scott Draper, Richard H. J. Willden, and Christopher R. Vogel. "The Fluid Mechanics of Tidal Stream Energy Conversion." Annual Review of Fluid Mechanics 53, no. 1 (January 5, 2021): 287–310. http://dx.doi.org/10.1146/annurev-fluid-010719-060207.
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Placing mechanical devices into fast-moving tidal streams to generate clean and predictable electricity is a developing technology. This review covers the fundamental fluid mechanics of this application, which is important for understanding how such devices work and how they interact with the tidal stream resource. We focus on how tidal stream turbines and energy generation are modeled analytically, numerically, and experimentally. Owing to the nature of the problem, our review is split into different scales—from turbine to array and regional—and we examine each in turn.
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Chan, Eric K. W., Yixin Zhang, and David Dudgeon. "Arthropod 'rain' into tropical streams: the importance of intact riparian forest and influences on fish diets." Marine and Freshwater Research 59, no. 8 (2008): 653. http://dx.doi.org/10.1071/mf07191.
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Terrestrial arthropods might represent an important energy source for stream predators, but these trophic linkages have seldom been studied in the tropics. Terrestrial arthropod inputs (essentially, arthropod ‘rain’) into four streams with different riparian vegetation (two draining shrublands and two draining forests) were measured over three consecutive seasons (dry, wet, dry) from 2005 to 2007 in monsoonal Hong Kong. Predatory minnows, Parazacco spilurus (Cyprinidae), were collected and their consumption of terrestrial arthropods was estimated. Inputs of arthropods were dominated by Diptera, Collembola, Formicidae and aerial Hymenoptera, accounting for ≥73% of the arthropod abundance. Seasonal variation was marked: numbers in the dry seasons were approximately half (47–57%) those in the wet season, and biomass fell to one-third (33–37%) of the wet-season value. Shrubland streams received 19–43% fewer individuals and 6–34% less biomass than shaded forest streams. An analysis of fish diets in three of the four streams showed that terrestrial insects and spiders were more important prey in the two forest streams, accounting for 35–43% of prey abundance (39–43% by volume) v. 28% (27%) in the shrubland stream. Because riparian vegetation is the source of terrestrial arthropod inputs to streams, degradation of streamside forests that reduce these inputs will have consequences for the diets of stream fishes.
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Omoniyi, Gbenga Emmanuel, Benjamin Bergerot, Laura Pellan, Maëva Delmotte, Alain Crave, Joris Heyman, and Christophe Piscart. "In-Stream Variability of Litter Breakdown and Consequences on Environmental Monitoring." Water 13, no. 16 (August 17, 2021): 2246. http://dx.doi.org/10.3390/w13162246.
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Energy derived from leaf litter decomposition fuels food webs in forested streams. However, the natural spatial variability of the decomposition rate of leaf litter and the relative contributions of its drivers are poorly known at the local scale. This study aims to determine the natural in-stream variability of leaf litter decomposition rates in successive riffles and to quantify the factors involved in this key ecosystem process at the local scale. Experiments were conducted on six successive riffles in nine streams in north-western France to monitor the decomposition rate in fine (microbial decomposition, kf) and coarse (total decomposition, kc) mesh bags. We recorded 30 ± 2% (mean ± S.E.) variation in kc among riffles and 43 ± 4% among streams. kf variability was 15 ± 1% among riffles and 20 ± 3% among streams. However, in-stream variability was higher than between-stream variability in four of the nine streams. Streambed roughness was negatively related to decomposition and was the most important factor for both total and microbial decomposition. Our study shows that the natural variability of the decomposition rate resulting from the local morphological conditions of habitats could be very important and should be taken into consideration in studies using leaf litter assays as a bio-indicator of anthropogenic impacts in streams.
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Thuy, Ngo Thi Phuong, Rajashekhar Pendyala, and Narahari Marneni. "Heat Exchanger Network Optimization Using Differential Evolution with Stream Splitting." Applied Mechanics and Materials 625 (September 2014): 373–77. http://dx.doi.org/10.4028/www.scientific.net/amm.625.373.
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Reduction in energy consumption is an important task in process industry. The basic idea of heat exchanger network (HEN) is using cold streams to cool hot streams and hot streams to heat cold streams. Hence, synthesis and optimization of HEN is a main tool for improving heat recovery. This article introduces a new strategy for HEN optimization using differential evolution algorithm. The proposed method considers splitting stream at the pinch point, to minimize the total cost of the network. Primarily, the minimum approach temperature value is determined through super-targeting. Then, differential evolution is employed to specify the heat load of heat exchangers and splitting streams. The HEN structure obtained in this work has better economics and illustrates the better performance by this approach.
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Kawashima, Hiroyuki, and Motoyuki Suzuki. "Numerical Simulation Model for Prediction of BOD Removal Rate in Streams." Water Science and Technology 21, no. 8-9 (August 1, 1989): 1003–14. http://dx.doi.org/10.2166/wst.1989.0302.
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A numerical simulation model is developed in order to predict BOD removal rate in streams on the basis of mass transfer and biochemical reaction kinetics. The double layer model of a flat aerobic and anaerobic bacterial film applies to BOD and DO balances in a stream. A relationship which relates energy dissipation, BOD and DO concentrations in streams and surface area available for attached biomass to the BOD removal rate per unit area is proposed. The different oxygen consumption rates observed in actual streams can be explained by using the model proposed here.
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Clancy, Niall G., Janice Brahney, James Dunnigan, and Phaedra Budy. "Effects of a diatom ecosystem engineer (Didymosphenia geminata) on stream food webs: implications for native fishes." Canadian Journal of Fisheries and Aquatic Sciences 78, no. 2 (February 2021): 154–64. http://dx.doi.org/10.1139/cjfas-2020-0121.
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Stream habitat changes affecting primary consumers often indirectly impact secondary consumers such as fishes. Blooms of the benthic algae Didymosphenia geminata (Didymo) are known to affect stream macroinvertebrates, but the potential indirect trophic impacts on fish consumers are poorly understood. In streams of the Kootenai River basin, we quantified the diet, condition, and growth rate of species of trout, char, and sculpin. In 2018, macroinvertebrate taxa composition was different between a stream with Didymo and a stream without, but trout diets, energy demand, and growth rates were similar. Trout abundance was higher in the stream with Didymo, but the amount of drifting invertebrates was higher in the stream without. In 2019, we surveyed 28 streams with a gradient of coverage. Didymo abundance was correlated only with the percentage of aquatic invertebrates in trout diets and was not related to diets of char or sculpin or condition of any species. Thus, we found no evidence for a trophic link between Didymo blooms and the condition or growth of trout, char, or sculpin in mountainous headwater streams.
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Johnson, Sherri L. "Factors influencing stream temperatures in small streams: substrate effects and a shading experiment." Canadian Journal of Fisheries and Aquatic Sciences 61, no. 6 (June 1, 2004): 913–23. http://dx.doi.org/10.1139/f04-040.
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The temperature of stream water is an important control of many in-stream processes. To better understand the processes and consequences of solar energy inputs to streams, stream temperature dynamics were examined before, during, and after experimental shading of a 150-m reach of a second-order stream in the Oregon Cascade Range. Maximum water temperatures declined significantly in the shaded reach, but minimum and mean temperatures were not modified. Heat budget calculations before shading show the dominance of solar energy as an influence of stream temperature. The influence of substrate type on stream temperature was examined separately where the water flowed first over bedrock and then through alluvial substrates. Maximum temperatures in the upstream bedrock reach were up to 8.6 °C higher and 3.4 °C lower than downstream in the alluvial reach. Better understanding of factors that influence not only maximum but minimum temperatures as well as diurnal temperature variation will highlight types of reaches in which stream temperature would be most responsive to changes in shading. Many apparent discrepancies in stream temperature literature can be explained by considering variation in the relative importance of different stream temperature drivers within and among streams and over time.
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Cortés Guzmán, Daniela, Javier Alcocer, José Daniel Cuevas Lara, Ismael Soria Reinoso, Luis A. Oseguera, and Martín Merino-Ibarra. "Organic matter seasonality and ecosystem metabolism in two tropical first-order streams." Limnetica 41, no. 2 (June 15, 2022): 1. http://dx.doi.org/10.23818/limn.41.19.
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Dissolved and particulate organic matter are the energy source for secondary production in forested streams. Cycling of or¬ganic matter and stream ecosystem functioning are linked to organic matter input and storage capacity and timing. This study assessed the seasonal variation (dry and rainy seasons) of environmental parameters, organic matter stock and input, and stream metabolism in two first-order tropical streams in the Selva Lacandona, Mexico. We also aimed to identify the drivers of organic matter and stream metabolism seasonality. We found seasonal variation in organic matter stock and input correlated with trop¬ical seasonality. Dissolved organic matter and seston increased in the rainy season, while benthic primary producers and leaf litter stock and input increased in the dry season correlated with lower water discharge. Gross primary production increased in the dry season, while ecosystem respiration did not differ between seasons. Seasonality defined by the rainfall pattern and its effect on stream hydrology is the main driver of organic matter dynamics in tropical streams. However, environmental parameters and organic matter stock and input were not good predictors of stream metabolism.
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Li, T. S., S. E. Koposov, D. B. Zucker, G. F. Lewis, K. Kuehn, J. D. Simpson, A. P. Ji, et al. "The southern stellar stream spectroscopic survey (S5): Overview, target selection, data reduction, validation, and early science." Monthly Notices of the Royal Astronomical Society 490, no. 3 (October 3, 2019): 3508–31. http://dx.doi.org/10.1093/mnras/stz2731.
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ABSTRACT We introduce the southern stellar stream spectroscopy survey (S5), an on-going program to map the kinematics and chemistry of stellar streams in the southern hemisphere. The initial focus of S5 has been spectroscopic observations of recently identified streams within the footprint of the dark energy survey (DES), with the eventual goal of surveying streams across the entire southern sky. Stellar streams are composed of material that has been tidally striped from dwarf galaxies and globular clusters and hence are excellent dynamical probes of the gravitational potential of the Milky Way, as well as providing a detailed snapshot of its accretion history. Observing with the 3.9 m Anglo-Australian Telescope’s 2-degree-Field fibre positioner and AAOmega spectrograph, and combining the precise photometry of DES DR1 with the superb proper motions from Gaia DR2, allows us to conduct an efficient spectroscopic survey to map these stellar streams. So far S5 has mapped nine DES streams and three streams outside of DES; the former are the first spectroscopic observations of these recently discovered streams. In addition to the stream survey, we use spare fibres to undertake a Milky Way halo survey and a low-redshift galaxy survey. This paper presents an overview of the S5 program, describing the scientific motivation for the survey, target selection, observation strategy, data reduction, and survey validation. Finally, we describe early science results on stellar streams and Milky Way halo stars drawn from the survey. Updates on S5, including future public data releases, can be found at http://s5collab.github.io.
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Rauch, Martina, and Antun Galovic. "Energy analysis of heat exchanger in a heat exchanger network." Thermal Science 22, no. 5 (2018): 1999–2011. http://dx.doi.org/10.2298/tsci171231216r.
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For many years now, heat exchanger optimization has been a field of research for a lot of scientists. Aims of optimization are different, having in mind heat exchanger networks with different temperatures of certain streams. In this paper mathematical model in dimensionless form is developed, describing operation of one heat exchanger in a heat exchanger network, with given overall area, based on the maximum heat-flow rate criterion. Under the presumption of heat exchanger being a part of the heat exchanger network, solution for the given task is resting in a possibility of connecting an additional fluid stream with certain temperature on a certain point of observed heat exchanger area. The connection point of additional fluid stream determines the exchanging areas of both heat exchangers and it needs to allow the maximum exchanged heat-flow rate. This needed heat-flow rate achieves higher value than the heat-flow rate acquired by either of streams. In other words, a criterion for the existence of the maximum heat-flow rate, as a local extremum, is obtained within this mathematical model. Results of the research are presented by the adequate diagrams and are interpreted, with emphasis on the cases which fulfill and those which do not fulfill the given condition for achieving the maximum heat-flow rate.
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Shipp, Nora, Denis Erkal, Alex Drlica-Wagner, Ting S. Li, Andrew B. Pace, Sergey E. Koposov, Lara R. Cullinane, et al. "Measuring the Mass of the Large Magellanic Cloud with Stellar Streams Observed by S 5." Astrophysical Journal 923, no. 2 (December 1, 2021): 149. http://dx.doi.org/10.3847/1538-4357/ac2e93.
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Abstract Stellar streams are excellent probes of the underlying gravitational potential in which they evolve. In this work, we fit dynamical models to five streams in the Southern Galactic hemisphere, combining observations from the Southern Stellar Stream Spectroscopic Survey (S 5), Gaia EDR3, and the Dark Energy Survey, to measure the mass of the Large Magellanic Cloud (LMC). With an ensemble of streams, we find a mass of the LMC ranging from ∼14–19 × 1010 M ⊙, probed over a range of closest approach times and distances. With the most constraining stream (Orphan–Chenab), we measure an LMC mass of 18.8 − 4.0 + 3.5 × 10 10 M ⊙ , probed at a closest approach time of 310 Myr and a closest approach distance of 25.4 kpc. This mass is compatible with previous measurements, showing that a consistent picture is emerging of the LMC’s influence on structures in the Milky Way. Using this sample of streams, we find that the LMC’s effect depends on the relative orientation of the stream and LMC at their point of closest approach. To better understand this, we present a simple model based on the impulse approximation and we show that the LMC’s effect depends both on the magnitude of the velocity kick imparted to the stream and the direction of this kick.
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Eckert, E. R. G. "Cross transport of energy in fluid streams." Wärme- und Stoffübertragung 21, no. 2-3 (March 1987): 73–81. http://dx.doi.org/10.1007/bf01377562.
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Yates, Nick, Ian Walkington, Richard Burrows, and Judith Wolf. "Appraising the extractable tidal energy resource of the UK's western coastal waters." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 371, no. 1985 (February 28, 2013): 20120181. http://dx.doi.org/10.1098/rsta.2012.0181.
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A two-dimensional west coast tidal model, built on the ADCIRC platform (an unstructured grid two-dimensional depth-integrated shallow water model), has been developed to examine the scope for reliable and fully predictable electricity generation from UK coastal waters using an ambitious combination of estuary barrages, tidal lagoons and tidal stream generator arrays. The main emphasis has been towards conjunctive operation of major estuary barrages, initially including the presence of pilot-scale tidal stream developments, though ambitious exploitation of extensive tidal streams has also been explored.
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Kahlke, Sven-Lasse, Martin Pumpa, Stefan Schütz, Alfons Kather, and Heike Rütters. "Potential Dynamics of CO2 Stream Composition and Mass Flow Rates in CCS Clusters." Processes 8, no. 9 (September 18, 2020): 1188. http://dx.doi.org/10.3390/pr8091188.
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Temporal variations in CO2 stream composition and mass flow rates may occur in a CO2 transport network, as well as further downstream when CO2 streams of different compositions and temporally variable mass flow rates are fed in. To assess the potential impacts of such variations on CO2 transport, injection, and storage, their characteristics must be known. We investigated variation characteristics in a scenario of a regional CO2 emitter cluster of seven fossil-fired power plants and four industrial plants that feed captured CO2 streams into a pipeline network. Variations of CO2 stream composition and mass flow rates in the pipelines were simulated using a network analysis tool. In addition, the potential effects of changes in the energy mix on resulting mass flow rates and CO2 stream compositions were investigated for two energy mix scenarios that consider higher shares of renewable energy sources or a replacement of lignite by hard coal and natural gas. While resulting maximum mass flow rates in the trunk line were similar in all considered scenarios, minimum flow rates and pipeline capacity utilisation differed substantially between them. Variations in CO2 stream composition followed the power plants’ operational load patterns resulting e.g., in stronger composition variations in case of higher renewable energy production.
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Van den Bulck, E., S. A. Klein, and J. W. Mitchell. "Second Law Analysis of Solid Desiccant Rotary Dehumidifiers." Journal of Solar Energy Engineering 110, no. 1 (February 1, 1988): 2–9. http://dx.doi.org/10.1115/1.3268233.
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This paper presents a second law analysis of solid desiccant rotary dehumidifiers. The equations for entropy generation for adiabatic flow of humid air over a solid desiccant are developed. The generation of entropy during operation of a rotary dehumidifier with infinite transfer coefficients is investigated and the various sources of irreversibility are identified and quantified. As they pass through the dehumidifier, both the process and regeneration air streams acquire nonuniform outlet states, and mixing both of these air streams to deliver homogeneous outlet streams is irreversible. Transfer of mass and energy between the regeneration air stream and the desiccant matrix occurs across finite differences in vapor pressure and temperature and these transfer processes generate entropy. The second law efficiency of the dehumidifier is given as a function of operating conditions and the effect of finite transfer coefficients for an actual dehumidifier is discussed. It is shown that operating the rotary dehumidifier at conditions that minimize regeneration energy also yields a local maximum for the second law efficiency.
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Augusto, Fernanda G., Aline F. Figueiredo, Plinio B. Camargo, Luciana D. Coletta, Edmar A. Mazzi, and Luiz A. Martinelli. "C3 and C4 plant leaf breakdown and assimilation by aquatic macroinvertebrates in streams of the Brazilian Atlantic Forest." Marine and Freshwater Research 71, no. 7 (2020): 814. http://dx.doi.org/10.1071/mf18430.
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The breakdown of allochthonous plants is of great importance in providing energy and nutrients in streams. In this regard, shredder macroinvertebrates play an important role in decomposing organic matter. Changes in land use strongly influence the type of material entering a stream, which ultimately affects the food chain dependent on this material. This study compared the decay of C3 (Mollinedia schottiana) and C4 (Brachiaria brizantha) plants in the montane Atlantic Forest of Brazil using litterbag experiments in two streams draining watersheds of different land uses. Concomitantly, we investigated the colonisation and assimilation of these plant detritus by aquatic macroinvertebrates. The breakdown of C4 plants in the forest stream was faster than that of C3 plants; however, aquatic macroinvertebrates did not assimilate the C4 carbon. These results support other studies that have shown a greater abundance of shredders in montane tropical streams (lower temperature) than in lowland streams. Moreover, the findings of this study support the view that changes in land use alter the structure of the benthic community, and that these changes can alter the leaf breakdown process.
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Cover, Matthew R., Juan A. de la Fuente, and Vincent H. Resh. "Catastrophic disturbances in headwater streams: the long-term ecological effects of debris flows and debris floods in the Klamath Mountains, northern California." Canadian Journal of Fisheries and Aquatic Sciences 67, no. 10 (October 2010): 1596–610. http://dx.doi.org/10.1139/f10-079.
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Debris flows and debris floods are catastrophic disturbances in steep, mountainous landscapes throughout the world, but little is known about the long-term ecological effects of these events on headwater streams. In 10 basins (10–20 km2) in the Klamath Mountains, northern California, USA, we used a space-for-time substitution to infer the long-term (10–100 years) effects of debris flows on stream ecosystem structure. Debris flows mobilized sediment and wood and removed riparian vegetation from large portions of channel networks. Stream temperatures were significantly warmer in streams that had recent debris flows (<10 years ago). Large wood, benthic organic matter, and detritivorous stoneflies were all very sparse in recent debris flow streams, suggesting that allochthonous energy pathways took decades to recover. Rainbow trout ( Oncorhynchus mykiss ) were abundant in recent debris flow streams, but populations of other vertebrates such as coastal giant salamander ( Dicamptodon tenebrosus ) and coastal tailed frog ( Ascaphus truei ) were virtually absent. Increased frequencies of catastrophic debris flows associated with forest management practices can have significant negative impacts on aquatic biodiversity in forested, mountainous landscapes.
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Aslam, Zahida, Hu Li, James Hammerton, Gordon Andrews, Andrew Ross, and Jon C. Lovett. "Increasing Access to Electricity: An Assessment of the Energy and Power Generation Potential from Biomass Waste Residues in Tanzania." Energies 14, no. 6 (March 23, 2021): 1793. http://dx.doi.org/10.3390/en14061793.
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Tanzania has a high rural population, of which many rely on off-grid diesel generators to produce electricity. The focus of this paper is to assess if the waste biomass residues in Tanzania have sufficient energy potential to produce renewable electrical energy for small-scale electricity generation using off-grid diesel generators coupled with anaerobic digestion (AD) and/or gasification. The gaseous fuel produced can then be used to substitute diesel fuel used in small-scale dual fuel diesel gen-sets; thus, providing more affordable electricity whilst reducing dependency on fossil fuels. The biomass waste streams estimated are those arising from agriculture, forestry, livestock, and urban human waste. To answer this question, the energy potentials of each of these biomass waste streams are quantified, followed by further calculations to determine the electricity generation capacity per stream based on overall efficiencies of 10 and 25%. The results show that combined these waste streams have an energy potential of 385 PJ (for the base year of 2018) generated from 26,924 kilotonnes (kt). Collectively, these residues can produce at least 1.2 times the electricity generated nationally in 2018 using AD and gasification coupled with a diesel gen-set engine.
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Andersson, Luke C., and John D. Reynolds. "Habitat features mediate selective consumption of salmon by bears." Canadian Journal of Fisheries and Aquatic Sciences 75, no. 6 (June 2018): 955–63. http://dx.doi.org/10.1139/cjfas-2017-0055.
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Salmon provide a key source of marine-derived nutrients to aquatic and surrounding terrestrial habitats in coastal areas of the North Pacific. Bears are a major predator of salmon and provide an important pathway for carcass transfer to riparian zones. We studied selective consumption of salmon (Oncorhynchus keta and Oncorhynchus gorbuscha) by bears (Ursus arctos and Ursus americanus) on 12 streams on the central coast of British Columbia, Canada. We predicted that bears would select more energy-rich parts, and eat less of each fish (i.e., selective consumption), in streams with more prey and simpler habitat (i.e., streams that facilitate salmon capture). Bears were 12% more likely to consume fish selectively in narrow, shallow streams with less pool volume, where salmon are easier to catch, than in deep, wide streams. However, bears were also 21% more likely to selectively consume fish in streams with more wood obstacles and undercut banks, where hunting was predicted to be more difficult. This suggests that stream characteristics can have significant indirect effects on riparian nutrient subsidies to ecosystems through selective feeding by bears.
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Kohil, Ahmed, Hassan Farag, and Mona Ossman. "Mathematical modeling of a multi-stream brazed aluminum plate fin heat exchanger." Thermal Science 14, no. 1 (2010): 103–14. http://dx.doi.org/10.2298/tsci1001103k.
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The need for small size and lightweight heat exchangers in many applications has resulted in the development of many heat transfer surfaces. This type of heat exchanger is much more compact than can be practically realized with circular tubes. In this work a steady-state mathematical model that representing one of the plate fin heat exchangers enclosed in cold box of an ethylene plant has been developed. This model could evaluate the performance of the heat exchanger by predicting the outlet temperatures of the hot and cold streams when the inlet conditions are known. The model has been validated by comparing the results with actual operating values and the results showed good agreement with the actual data. Sensitivity analysis was applied on the model to illustrate the main parameters that have the greatest influence on the model calculated results. The sensitivity analysis showed that the hot stream outlet temperature is more sensitive to cold streams inlet temperatures and less sensitive to hot stream inlet temperature and thermal resistance (fouling), while the cold stream outlet temperature is more sensitive to cold streams inlet flow rate and less sensitive to fouling.
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Ma, Hui Fang, and Hui Li Ma. "Combining Burst Detection for Hot Topic Extraction." Advanced Materials Research 268-270 (July 2011): 1283–88. http://dx.doi.org/10.4028/www.scientific.net/amr.268-270.1283.
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As traditional text representations are not suitable for online dynamic streams, this paper presents a hot topic extraction technique that can be used for tracking news topics over time. The model combines individual word burst into the document-word vector representation, which can emphasize the temporally features of text streams. An energy ratio threshold based burst detection approach is proposed and TF-PDF is then combined to weigh the terms. Experiment results demonstrate that this model is effective in topic extraction for news stream and it can better improve the clustering performance.
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Iwasaki, Toshiki, Takamichi Shoji, Yuki Kanno, Masahiro Sawada, Masashi Ujiie, and Koutarou Takaya. "Isentropic Analysis of Polar Cold Airmass Streams in the Northern Hemispheric Winter." Journal of the Atmospheric Sciences 71, no. 6 (May 30, 2014): 2230–43. http://dx.doi.org/10.1175/jas-d-13-058.1.
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Abstract An analysis method is proposed for polar cold airmass streams from generation to disappearance. It designates a threshold potential temperature θT at around the turning point of the extratropical direct (ETD) meridional circulation from downward to equatorward in the mass-weighted isentropic zonal mean (MIM) and clarifies the geographical distributions of the cold air mass, the negative heat content (NHC), their horizontal fluxes, and their diabatic change rates on the basis of conservation relations of the air mass and thermodynamic energy. In the Northern Hemispheric winter, the polar cold air mass below θT = 280 K has two main streams: the East Asian stream and the North American stream. The former grows over the northern part of the Eurasian continent, flows eastward, turns down southeastward toward East Asia via Siberia, and disappears over the western North Pacific Ocean. The latter grows over the Arctic Ocean, flows toward the eastern coast of North America via Hudson Bay, and disappears over the western North Atlantic Ocean. In their exit regions, wave–mean flow interactions are considered to transfer the angular momentum from the cold airstreams to the upward Eliassen–Palm flux and convert the available potential energy to wave energy.
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BENOIT, ANNE, RAMI MELHEM, PAUL RENAUD-GOUD, and YVES ROBERT. "ASSESSING THE PERFORMANCE OF ENERGY-AWARE MAPPINGS." Parallel Processing Letters 23, no. 02 (June 2013): 1340003. http://dx.doi.org/10.1142/s0129626413400033.
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We aim at mapping streaming applications that can be modeled by a series-parallel graph onto a 2-dimensional tiled chip multiprocessor (CMP) architecture. The objective of the mapping is to minimize the energy consumption, using dynamic voltage and frequency scaling (DVFS) techniques, while maintaining a given level of performance, reflected by the rate of processing the data streams. This mapping problem turns out to be NP-hard, and several heuristics are proposed. We assess their performance through comprehensive simulations using the StreamIt workflow suite and randomly generated series-parallel graphs, and various CMP grid sizes.
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Yang, M. I., E. A. Edwards, and D. G. Allen. "Anaerobic treatability and biogas production potential of selected in-mill streams." Water Science and Technology 62, no. 10 (November 1, 2010): 2427–34. http://dx.doi.org/10.2166/wst.2010.980.
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Biochemical methane potential assays (BMP assays) were performed to study the potential of anaerobic treatment of in-mill wastewaters. The assay results indicated that condensate and the BCTMP effluent, which are currently treated with the anaerobic internal circulation reactors, were the best streams for anaerobic treatment because of their relatively high degradability (>80%) and initial rates of biogas production. The softwood dewatering process stream was the worst with the lowest degradability (∼30%). The hardwood stream was more degradable than the softwood stream from the same process. Biogas production was found to be additive and predictable in blended samples. In addition, degradability was found to be negatively correlated to the concentration of dehydroabietic acid and tannin-lignin compounds. The anaerobic treatment of the suitable streams has great potential value with significantly reduced sludge production and energy savings.
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Wang, Fen, Zhi Xia He, Yue Ma, and Chang Si Li. "Numerical Simulation of the Hydrodynamic Cavitation of the Impinging Streams Mixer." Advanced Materials Research 945-949 (June 2014): 951–55. http://dx.doi.org/10.4028/www.scientific.net/amr.945-949.951.
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The impinging streams mixer is a new type micromixer. The cavitation phenomenon occurring in the mixers with T-shaped impinging streams (TS), conical impinging streams (CIS), vortex streams(VS) were investigated, respectively. The distribution of flow field in the mixer was simulated and calculated by commercial software Fluent 6.2.1. The results showed that under the same working conditions, a more obvious hydrodynamic cavitation may occur in the CIS type impinging stream than that in the CIS type or the VS type, and the vortex flow lead to an extension of the material residence time in the mixer. The distribution of turbulent kinetic energy and gas holdup were obtained by numerical simulating hydrodynamic cavitation under different entrance pressure conditions. It is showed that when the outlet pressure keeps a constant value, hydrodynamic cavitation can be enhanced by increasing the entrance pressure. The above research can be contributed to the producing of biodiesel and the solving of the key technical problem of oil and alcohol heterogeneous mixing.
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Venslauskas, Kęstutis, Kęstutis Navickas, Marja Nappa, Petteri Kangas, Revilija Mozūraitytė, Rasa Šližytė, and Vidmantas Župerka. "Energetic and Economic Evaluation of Zero-Waste Fish Co-Stream Processing." International Journal of Environmental Research and Public Health 18, no. 5 (February 28, 2021): 2358. http://dx.doi.org/10.3390/ijerph18052358.
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This study evaluates the possibility of recovery of high-quality valuable fish oil and proteins from fish co-streams by traditional means or a combination of several technologies. A techno-economically feasible and sustainable zero-waste process is needed for full utilisation of this co-stream’s potential. This study aims to determine the energy efficiency and economic feasibility of four different zero-waste bio-refineries based on salmon filleting co-streams. The study covers four concepts: (I) biogas and fertiliser production from salmon co-streams, (II) fish silage production, (III) thermal processing of salmon co-streams for producing oil, protein concentrate, and meal, and (IV) novel two-stage thermal and enzymatic process for producing high-quality oil and protein hydrolysate, while the solid residue is converted to biogas and fertilisers. Monte Carlo simulation is used to evaluate uncertainties in economic evaluation. The results show that the two-stage processing of fish co-streams leads to recovery of both high-quality marine oil and proteins, showing the largest profitability and return on investment during the economic analysis. It is a more tempting option than the currently used thermal treatment or traditional silage processes. The possibility of producing food-grade fish protein hydrolysate is the biggest benefit here. Concepts studied are examples of zero-waste processing of bioproducts and illustrate the possibilities and benefits of fully utilising the different fractions of fish as fillets, oil, protein, fertilisers, and energy production.
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Shipp, N., A. Drlica-Wagner, E. Balbinot, P. Ferguson, D. Erkal, T. S. Li, K. Bechtol, et al. "Stellar Streams Discovered in the Dark Energy Survey." Astrophysical Journal 862, no. 2 (July 30, 2018): 114. http://dx.doi.org/10.3847/1538-4357/aacdab.
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Hughes, Ben Richard, Hassam Nasarullah Chaudhry, and John Kaiser Calautit. "Passive energy recovery from natural ventilation air streams." Applied Energy 113 (January 2014): 127–40. http://dx.doi.org/10.1016/j.apenergy.2013.07.019.
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Hammer, James H. "Mass Streams for Spacecraft Propulsion and Energy Generation." Journal of Propulsion and Power 22, no. 5 (September 2006): 1111–16. http://dx.doi.org/10.2514/1.19916.
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Gajowniczek, Krzysztof, Marcin Bator, Tomasz Ząbkowski, Arkadiusz Orłowski, and Chu Kiong Loo. "Simulation Study on the Electricity Data Streams Time Series Clustering." Energies 13, no. 4 (February 19, 2020): 924. http://dx.doi.org/10.3390/en13040924.
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Currently, thanks to the rapid development of wireless sensor networks and network traffic monitoring, the data stream is gradually becoming one of the most popular data generating processes. The data stream is different from traditional static data. Cluster analysis is an important technology for data mining, which is why many researchers pay attention to grouping streaming data. In the literature, there are many data stream clustering techniques, unfortunately, very few of them try to solve the problem of clustering data streams coming from multiple sources. In this article, we present an algorithm with a tree structure for grouping data streams (in the form of a time series) that have similar properties and behaviors. We have evaluated our algorithm over real multivariate data streams generated by smart meter sensors—the Irish Commission for Energy Regulation data set. There were several measures used to analyze the various characteristics of a tree-like clustering structure (computer science perspective) and also measures that are important from a business standpoint. The proposed method was able to cluster the flows of data and has identified the customers with similar behavior during the analyzed period.
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Bozek, Michael A., and Wayne A. Hubert. "Segregation of resident trout in streams as predicted by three habitat dimensions." Canadian Journal of Zoology 70, no. 5 (May 1, 1992): 886–90. http://dx.doi.org/10.1139/z92-126.
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We assessed the relation of three measures of habitat to the distribution of four species of Salmonidae, cutthroat trout (Oncorhynchus clarki), brook trout (Salvelinus fontinalis), brown trout (Salmo trutta), and rainbow trout (Oncorhynchus mykiss), in streams of the central Rocky Mountains. We examined whether single measures of three habitat dimensions (climate, stream energy, and stream size) could account for current distribution patterns of four resident trout species in Wyoming. The three habitat dimensions were represented by three habitat variables: elevation, channel gradient, and wetted stream width. Considerable overlap in the ranges of elevation, gradient, and wetted width was observed among reaches where the four species were found, but differences in the mean values of these habitat features were observed among species. Using discriminant analysis, we categorized the presence and absence of individual species in stream reaches by the three habitat variables. We successfully predicted the presence of brook trout (87%), cutthroat trout (59%), brown trout (50%), and rainbow trout (39%) in streams, but the absence of each species was predicted more successfully (rainbow trout (94%), brown trout (94%), cutthroat trout (90%), and brook trout (57%)). The three habitat features were useful in describing the segregation of trout species in streams of the central Rocky Mountains.
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Ferreira, Fabio Cop, André Teixeira da Silva, Cristina da Silva Gonçalves, and Miguel Petrere Jr. "Disentangling the influences of habitat structure and limnological predictors on stream fish communities of a coastal basin, southeastern Brazil." Neotropical Ichthyology 12, no. 1 (March 2014): 177–86. http://dx.doi.org/10.1590/s1679-62252014000100019.
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In stream environments habitat structure and limnological factors interact regulating patterns of energy and material transfer and affecting fish communities. In the coastal basins of Southeastern Brazil, limnological and structural characteristics differ between clear and blackwaters streams. The former have a diversity of substrate types, higher water velocities, and lower water conductivity, while the latter have sandy substrate, tea-colored and acidic waters, and low water velocities. In this study, we verified the relative importance of habitat structure and limnological variables in predicting patterns of variation in stream fish communities. Eight first to third order streams were sampled in the coastal plain of Itanhaém River basin. We captured 34 fish species and verified that community structure was influenced by physical habitat and limnology, being the former more important. A fraction of the variation could not be totally decomposed, and it was assigned to the joint influence of limnology and habitat structure. Some species that were restricted to blackwater streams, may have physiological and behavioral adaptations to deal with the lower pH levels. When we examined only the clearwater streams, all the explained variation in fish community composition was assigned to structural factors, which express specific preferences for different types of habitats.