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Sample records for bed load transport

  1. Manual for computing bed load transport using BAGS (Bedload Assessment for Gravel-bed Streams) Software

    Science.gov (United States)

    John Pitlick; Yantao Cui; Peter Wilcock

    2009-01-01

    This manual provides background information and instructions on the use of a spreadsheet-based program for Bedload Assessment in Gravel-bed Streams (BAGS). The program implements six bed load transport equations developed specifically for gravel-bed rivers. Transport capacities are calculated on the basis of field measurements of channel geometry, reach-average slope,...

  2. Bed Load Transport in Channels with Bank Vegetation

    Science.gov (United States)

    Specht, F.-J.

    2003-04-01

    Natural and restored rivers are dominated to a high extent by the vegetation at the banks and on the flood plains of the river. Especially, the interactive zone between the region of water flow through the vegetation and the region of free flowing water in the main channel is of great importance. It is characterized by large vortices at the interface of these two regions. The vortices have an influence on the flow resistance, especially on bed shear stress and thus on bed load transport and dune shape. The aim of the study was to investigate the hydraulic/sedimentological processes in a trapezoidal channel depending on the arrangement of the vegetation and channel width. Laboratory experiments were carried out in a 30 m long and 2.0 m wide tilting flume. The sand of the bed (d50 = 0.82 mm) was recirculated. The arrangement of the bank vegetation (made of rigid PVC-sticks with a diameter of 10 mm, bank slope 1:1) and the width B of the channel bed was variied from B = 0.4 m to B = 1.2 m to investigate the influence of channel width on the overall processes. Based on the experimental results, the existing bed load formulas were verified to determine the influence of rigid bank vegetation on bed load transport. In the case of wide channels (B/h > 3, with h = water depth) the deviation between measured and calculated values was low. However, in the case of narrow channels (B/h bank vegetation down to the river bed the measured transport rates were 52% higher than the calculated ones and in the extreme case of B/h load transport formulas could be modified. In the experiments a significant influence of the vegetation on the occurring dunes was observed. In the series without vegetation the dune crests and vales were horizontally distributed over the width. Especially, the dune vales close to the vegetation zones are scoured in the series with vegetation. The dune crests were tilted in the cross-section of the channel in the series with vegetation on one bank only. As a

  3. Relaxation approximation to bed-load sediment transport

    Science.gov (United States)

    Delis, A. I.; Papoglou, I.

    2008-04-01

    In this work we propose and apply a numerical method based on finite volume relaxation approximation for computing the bed-load sediment transport in shallow water flows, in one and two space dimensions. The water flow is modeled by the well-known nonlinear shallow water equations which are coupled with a bed updating equation. Using a relaxation approximation, the nonlinear set of equations (and for two different formulations) is transformed to a semilinear diagonalizable problem with linear characteristic variablesE A second order MUSCL-TVD method is used for the advection stage while an implicit-explicit Runge-Kutta scheme solves the relaxation stage. The main advantages of this approach are that neither Riemann problem solvers nor nonlinear iterations are required during the solution process. For the two different formulations, the applicability and effectiveness of the presented scheme is verified by comparing numerical results obtained for several benchmark test problems.

  4. Influence of turbulence on bed load sediment transport

    DEFF Research Database (Denmark)

    Sumer, B. Mutlu; Chua, L.; Cheng, N. S.

    2003-01-01

    -bed experiments and the ripple-covered-bed experiments. In the former case, the flow in the presence of the turbulence generator was adjusted so that the mean bed shear stress was the same as in the case without the turbulence generator in order to single out the effect of the external turbulence on the sediment...... transport. In the ripple-covered-bed case, the mean and turbulence quantities of the streamwise component of the velocity were measured, and the Shields parameter, due to skin friction, was determined. The Shields parameter, together with the r.m.s. value of the streamwise velocity fluctuations, were...

  5. Performance of bed-load transport equations relative to geomorphic significance: Predicting effective discharge and its transport rate

    Science.gov (United States)

    Jeffrey J. Barry; John M. Buffington; Peter Goodwin; John .G. King; William W. Emmett

    2008-01-01

    Previous studies assessing the accuracy of bed-load transport equations have considered equation performance statistically based on paired observations of measured and predicted bed-load transport rates. However, transport measurements were typically taken during low flows, biasing the assessment of equation performance toward low discharges, and because equation...

  6. Sediment and Fecal Indicator Bacteria Loading in a Mixed Land Use Watershed: Contributions from Suspended and Bed Load Transport

    Science.gov (United States)

    Water quality studies that quantify sediment and fecal bacteria loading commonly focus on suspended contaminants transported during high flows. Fecal contaminants in bed sediments are typically ignored and need to be considered because of their potential to increase pathogen load...

  7. The role of velocity, pressure, and bed stress fluctuations in bed load transport over bed forms: numerical simulation downstream of a backward-facing step

    Directory of Open Access Journals (Sweden)

    M. W. Schmeeckle

    2015-02-01

    Full Text Available Bed load transport over ripples and dunes in rivers exhibits strong spatial and temporal variability due to the complex turbulence field caused by flow separation at bedform crests. A turbulence-resolving flow model downstream of a backward-facing step, coupled with a model integrating the equations of motion of individual sand grains, is used to investigate the physical interaction between bed load motion and turbulence downstream of separated flow. Large bed load transport events are found to correspond to low-frequency positive pressure fluctuations. Episodic penetration of fluid into the bed increases the bed stress and moves grains. Fluid penetration events are larger in magnitude near the point of reattachment than farther downstream. Models of bed load transport over ripples and dunes must incorporate the effects of these penetration events of high stress and sediment flux.

  8. The role of velocity, pressure, and bed stress fluctuations in bed load transport over bed forms: numerical simulation downstream of a backward-facing step

    Science.gov (United States)

    Schmeeckle, M. W.

    2015-02-01

    Bed load transport over ripples and dunes in rivers exhibits strong spatial and temporal variability due to the complex turbulence field caused by flow separation at bedform crests. A turbulence-resolving flow model downstream of a backward-facing step, coupled with a model integrating the equations of motion of individual sand grains, is used to investigate the physical interaction between bed load motion and turbulence downstream of separated flow. Large bed load transport events are found to correspond to low-frequency positive pressure fluctuations. Episodic penetration of fluid into the bed increases the bed stress and moves grains. Fluid penetration events are larger in magnitude near the point of reattachment than farther downstream. Models of bed load transport over ripples and dunes must incorporate the effects of these penetration events of high stress and sediment flux.

  9. Influence of turbulence on bed load sediment transport

    DEFF Research Database (Denmark)

    Sumer, B. Mutlu; Chua, L.; Cheng, N. S.

    2003-01-01

    -bed experiments and the ripple-covered-bed experiments. In the former case, the flow in the presence of the turbulence generator was adjusted so that the mean bed shear stress was the same as in the case without the turbulence generator in order to single out the effect of the external turbulence on the sediment...

  10. An experimental analysis of bed load transport in gravel-bed braided rivers with high grain Reynolds numbers

    Science.gov (United States)

    De Vincenzo, Annamaria; Brancati, Francesco; Pannone, Marilena

    2016-08-01

    Laboratory experiments were performed with nearly uniform fluvial gravel (D50=9 mm, D10=5 mm and D90=13 mm) to analyse the relationship between stream power and bed load transport rate in gravel-bed braided rivers at high grain Reynolds numbers. The values of the unit-width dimensionless bed-load rate qb* and unit-width dimensionless stream power ω* were evaluated in equilibrium conditions based on ten different experimental runs. Then, they were plotted along with values obtained during particularly representative field studies documented in the literature, and a regression law was derived. For comparison, a regression analysis was performed using the data obtained from laboratory experiments characterized by smaller grain sizes and, therefore, referring to relatively low grain Reynolds numbers. A numerical integration of Exner's equation was performed to reconstruct the local and time-dependent functional dependence of qb* and ω*. The results led to the following conclusions: 1) At equilibrium, the reach-averaged bed load transport rate is related to the reach-averaged stream power by different regression laws at high and low grain Reynolds numbers. Additionally, the transition from bed to suspended load transport is accelerated by low Re*, with the corresponding bed load discharge increasing with stream power at a lower, linear rate. 2) When tested against the gravel laboratory measurements, the high Re* power law derived in the present study performs considerably better than do previous formulas. 3) The longitudinal variability of the section-averaged equilibrium stream power is much more pronounced than that characterizing the bed load rate, at least for high Re*. Thus, the stream power and its local-scale heterogeneity seem to be directly responsible for transverse sediment re-distribution and, ultimately, for the determination of the spatial and temporal scales that characterize the gravel bedforms. 4) Finally, the stochastic interpretation of the wetted

  11. Effects of check dams on bed-load transport and steep-slope stream morphodynamics

    Science.gov (United States)

    Piton, Guillaume; Recking, Alain

    2017-08-01

    Check dams are transversal structures built across morphologically-active streams in mountainous regions. These structures have been used widely in torrent-hazard mitigation for over 150 years. Thousands of them are regularly maintained by stream managers and torrent-control services. The stabilization role of these structures is well known, i.e. they durably constrain the stream-bed through the creation of vertical and planar fixed points. What is not yet clear is to what extent check dams influence bed-load transport: How do peak solid discharge or flood-transported volume change when check dams are added to a reach? To address these questions, long-lasting small-scale experiments were conducted in a 4.8-m-long flume with either one, three or no structures. The results show that the addition of structures creates independent compartments in the bed level, which have a strong influence on bed surface armouring and stream morphodynamics: the consequence is that instantaneous transport intensities are unchanged, but peak solid discharge occur more often and for shorter duration. This results in the same total transported volume over the long term, but reduced volume for a single transport event. It reaffirms the observation of pioneering authors of the mid-19th and early 20th century who conceptualized the possible sediment transport regulation function of check dams: in addition to stabilizing the stream-bed, check dams influence bed-load transport through a buffering effect, releasing frequently and in small doses what, in their absence, would be transported abruptly en masse during rare extreme events.

  12. Radionuclide transport in running waters, sensitivity analysis of bed-load, channel geometry and model discretisation

    International Nuclear Information System (INIS)

    Jonsson, Karin; Elert, Mark

    2006-08-01

    In this report, further investigations of the model concept for radionuclide transport in stream, developed in the SKB report TR-05-03 is presented. Especially three issues have been the focus of the model investigations. The first issue was to investigate the influence of assumed channel geometry on the simulation results. The second issue was to reconsider the applicability of the equation for the bed-load transport in the stream model, and finally the last issue was to investigate how the model discretisation will influence the simulation results. The simulations showed that there were relatively small differences in results when applying different cross-sections in the model. The inclusion of the exact shape of the cross-section in the model is therefore not crucial, however, if cross-sectional data exist, the overall shape of the cross-section should be used in the model formulation. This could e.g. be accomplished by using measured values of the stream width and depth in the middle of the stream and by assuming a triangular shape. The bed-load transport was in this study determined for different sediment characteristics which can be used as an order of magnitude estimation if no exact determinations of the bed-load are available. The difference in the calculated bed-load transport for the different materials was, however, found to be limited. The investigation of model discretisation showed that a fine model discretisation to account for numerical effects is probably not important for the performed simulations. However, it can be necessary for being able to account for different conditions along a stream. For example, the application of mean slopes instead of individual values in the different stream reaches can result in very different predicted concentrations

  13. Propagation of hydrological modeling uncertainties on bed load transport simulations in steep mountain streams

    Science.gov (United States)

    Eichner, Bernhard; Koller, Julian; Kammerlander, Johannes; Schöber, Johannes; Achleitner, Stefan

    2017-04-01

    As mountain streams are sources of both, water and sediment, they are strongly influencing the whole downstream river network. Besides large flood flow events, the continuous transport of sediments during the year is in the focus of this work. Since small mountain streams are usually not measured, spatial distributed hydrological models are used to assess the internal discharges triggering the sediment transport. In general model calibration will never be perfect and is focused on specific criteria such as mass balance or peak flow, etc. The remaining uncertainties influence the subsequent applications, where the simulation results are used. The presented work focuses on the question, how modelling uncertainties in hydrological modelling impact the subsequent simulation of sediment transport. The applied auto calibration by means of MonteCarlo Simulation optimizes the model parameters for different aspects (efficiency criteria) of the runoff time series. In this case, we investigated the impacts of different hydrological criteria on a subsequent bed load transport simulation in catchment of the Längentaler Bach, a small catchment in the Stubai Alps. The used hydrologic model HQSim is a physically based semi-distributed water balance model. Different hydrologic response units (HRU), which are characterized by elevation, orientation, vegetation, soil type and depth, drain with various delay into specified river reaches. The runoff results of the Monte-Carlo simulation are evaluated in comparison to runoff gauge, where water is collected by the Tiroler Wasserkraft AG (TIWAG). Using the Nash-Sutcliffe efficiency (NSE) on events and main runoff period (summer), the weighted root mean squared error (RMSE) on duration curve and a combination of different criteria, a set of best fit parametrization with varying runoff series was received as input for the bed load transport simulation. These simulations are performed with sedFlow, a tool especially developed for bed load

  14. Comparison of genetic algorithm and imperialist competitive algorithms in predicting bed load transport in clean pipe.

    Science.gov (United States)

    Ebtehaj, Isa; Bonakdari, Hossein

    2014-01-01

    The existence of sediments in wastewater greatly affects the performance of the sewer and wastewater transmission systems. Increased sedimentation in wastewater collection systems causes problems such as reduced transmission capacity and early combined sewer overflow. The article reviews the performance of the genetic algorithm (GA) and imperialist competitive algorithm (ICA) in minimizing the target function (mean square error of observed and predicted Froude number). To study the impact of bed load transport parameters, using four non-dimensional groups, six different models have been presented. Moreover, the roulette wheel selection method is used to select the parents. The ICA with root mean square error (RMSE) = 0.007, mean absolute percentage error (MAPE) = 3.5% show better results than GA (RMSE = 0.007, MAPE = 5.6%) for the selected model. All six models return better results than the GA. Also, the results of these two algorithms were compared with multi-layer perceptron and existing equations.

  15. A Framework for Dynamic Modeling of Surface-Structure Patches on Bed Load Transport in Coarse Grained Reaches

    Science.gov (United States)

    Strom, K. B.

    2010-12-01

    Mountain streams are the first link in the fluvial system and often have complex bed morphologies which make it difficult to develop simple quantitative expressions for sediment mass flux and stream flow resistance. Such expressions are important for landscape evolution modeling as well as stream management and restoration practices and efforts. Part of the difficulty lies in the fact that stream beds can have large variations in particle size and structural organization - both of which lead to variations in bed strength that can change as a function of time. This study presents a mathematical framework to account for the dynamic impact of surface-structure patches on bed strength and bed load transport under simplified conditions. The framework is based on conservation principles for tracking the exchange of mass between structured and unstructured surface patches in the bed during structure formation and breakup. Two main transport equations are solved for the mobile and stationary phases, and the exchange between the two is modeled using particle collision theory and a simple breakup model (figure 1). The experiments of Strom et al. (2004) are used to parameterize the model initial conditions, and calculated and experimentally observed transport rates are compared as a function of time. Conceptual sketch of the modeling framework for: (A) a gravel bed, and (B) an idealized bed of uniform spherical particles. Mass conservation equations are written for each phase (structured and unstructured) and then solved with time under varying conditions.

  16. Use of 198 Au, with surface labelling, in the study of solid transport by bed load in large natural channels

    International Nuclear Information System (INIS)

    Nakahira, S.

    1987-01-01

    The present study aims to present a method of measuring the bed load transport using a radioisotope technique in large natural channels. This study describes the basic principles of radioisotope application in this field, emphasizing the use of 198 Au for surface labelling of a natural sediment. Moreover, it presents the theoretical aspects, critical analysis, recommendations and comments on the methodology proposed. (author)

  17. Bed load transport for a mixture of particle sizes: Downstream sorting rather than anomalous diffusion

    Science.gov (United States)

    Fan, Niannian; Xie, Yushu; Nie, Ruihua

    2017-10-01

    The stochastic nature of bed load transport induces diffusion of sediment tracers, which is governed by the dynamics of their bulk behavior over time. By deploying both numerical simulations and flume experiments, the emergent particle diffusion regimes for both uniform and mixed tracer particles were studied and compared. For uniform particles, power-law-distributed resting times Tr produced super-, sub- or normal diffusion regimes for certain values of the tail exponent ν . Based on the assumption that heterogeneity in particle size leads to a power-law distribution of Tr , a completely different diffusion regime emerges in mixtures compared with those obtained from uniform particles with the same value of the tail exponent ν . Mixtures exhibited the same ballistic regime (the variance of travel distance grows as time squared) for different values of ν , and ballistic regimes for mixtures also emerged from several other tested models. Furthermore, our experimental results confirmed the ballistic regime; however, the decreasing number of tracked particles may result in apparent but deceptive sub-diffusion. We conclude that ballistic regimes for mixtures result from violations of the independent and identically distributed (i.i.d.) assumptions, attributing to downstream sorting processes.

  18. A SPH elastic-viscoplastic model for granular flows and bed-load transport

    Science.gov (United States)

    Ghaïtanellis, Alex; Violeau, Damien; Ferrand, Martin; Abderrezzak, Kamal El Kadi; Leroy, Agnès; Joly, Antoine

    2018-01-01

    An elastic-viscoplastic model (Ulrich, 2013) is combined to a multi-phase SPH formulation (Hu and Adams, 2006; Ghaitanellis et al., 2015) to model granular flows and non-cohesive sediment transport. The soil is treated as a continuum exhibiting a viscoplastic behaviour. Thus, below a critical shear stress (i.e. the yield stress), the soil is assumed to behave as an isotropic linear-elastic solid. When the yield stress is exceeded, the soil flows and behaves as a shear-thinning fluid. A liquid-solid transition threshold based on the granular material properties is proposed, so as to make the model free of numerical parameter. The yield stress is obtained from Drucker-Prager criterion that requires an accurate computation of the effective stress in the soil. A novel method is proposed to compute the effective stress in SPH, solving a Laplace equation. The model is applied to a two-dimensional soil collapse (Bui et al., 2008) and a dam break over mobile beds (Spinewine and Zech, 2007). Results are compared with experimental data and a good agreement is obtained.

  19. Experiment on temporal variation of bed load transport in response to changes in sediment supply in streams

    Science.gov (United States)

    Elgueta-Astaburuaga, Maria A.; Hassan, Marwan A.

    2017-01-01

    A flume experiment was conducted to study channel adjustment to episodic sediment supply in mountain streams. The bulk sediment used for the bed and feed included grain sizes 0.5-64 mm with geometric mean Dg>(bulk>) of 5.7 mm. Water discharge was held constant for 40 h, and 300 kg of sediment was supplied through a range of scenarios. Bed slope, sediment storage, sediment transport, and bed surface texture responded to sediment supply. During the first of seven runs, bed slope decreased from 0.022 m/m (flume slope) to 0.018 m/m due to sediment starvation. Bed slope increased beginning in the second run as the bed aggraded due to preferential storage of grains >8 mm. Transport rate and bed-surface particle size were significantly affected by magnitude-frequency of sediment feed. Under constant feed, transport rate increased gradually and Dg >(surface>) ranged between 12 and 15 mm. Instead, sediment pulses caused a pronounced increase in sediment transport rate and surface fining, trends that were inverted as sediment evacuated. At the run scale, sediment transport and storage behaved as with constant feed if pulse relaxation time exceeded time between pulses. The increase in transport rate and surface fining were proportional to pulse size. After the 300 kg pulse, transport rate reached 100 g m-1 s-1 and Dg >(surface>) was g >(surface>) was >12 mm. Textural differences on the initial bed surface influenced the patterns of sediment transport. Channel adjustment was controlled by magnitude-frequency of sediment feed and not by total feed.

  20. Linking the spatial distribution of bed load transport to morphological change during high-flow events in a shallow braided river

    Science.gov (United States)

    Williams, R. D.; Rennie, C. D.; Brasington, J.; Hicks, D. M.; Vericat, D.

    2015-03-01

    This paper provides novel observations linking the connections between spatially distributed bed load transport pathways, hydraulic patterns, and morphological change in a shallow, gravel bed braided river. These observations shed light on the mechanics of braiding processes and illustrate the potential to quantify coupled material fluxes using remotely sensed methods. The paper focuses upon a 300 m long segment of the Rees River, New Zealand, and utilizes spatially dense observations from a mobile acoustic Doppler current profiler (aDcp) to map depth, velocity, and channel topography through a sequence of high-flow events. Apparent bed load velocity is estimated from the bias in aDcp bottom tracking and mapped to indicate bed load transport pathways. Terrestrial laser scanning (TLS) of exposed bar surfaces is fused with the aDcp surveys to generate spatially continuous digital elevation models, which quantify morphological change through the sequence of events. Results map spatially distributed bed load pathways that were likely to link zones of erosion and deposition. The coherence between the channel thalweg, zone of maximum hydraulic forcing, and maximum apparent bed load pathways varied. This suggests that, in places, local sediment supply sources exerted a strong control on the distribution of bed load, distinct from hydraulic forcing. The principal braiding mechanisms observed were channel choking, leading to subsequent bifurcation. Results show the connection between sediment sources, pathways, and sinks and their influence on channel morphology and flow path directions. The methodology of coupling spatially dense aDcp surveys with TLS has considerable potential to understand connections between processes and morphological change in dynamic fluvial settings.

  1. Bed-load transportmeter for find sand "Sphinx"

    NARCIS (Netherlands)

    Vinckers, J.B.; Bijker, E.W.; Schijf, J.B.

    1953-01-01

    A new bed-load transportmeter has been designed particularly for very fine bed material (below 400 micron). The basic conception is the same as for the so-called Delft-bottle used for measuring transport by turbulent suspension. The instrument is of the flow-through type. The flow enters through a

  2. Effects of bed-load movement on flow resistance over bed forms

    Indian Academy of Sciences (India)

    Abstract. The effect of bed-load transport on flow resistance of alluvial channels with undulated bed was experimentally investigated. The experiments were carried out in a tilting flume 250mm wide and 12·5m long with glass-sides of rectan- gular cross-section and artificial dune shaped floor that was made from Plexi-glass.

  3. Variability of bed mobility in natural, gravel-bed channels and adjustments to sediment load at local and reach scales

    Science.gov (United States)

    Thomas E. Lisle; Jonathan M. Nelson; John Pitlick; Mary Ann Madej; Brent L. Barkett

    2000-01-01

    Abstract - Local variations in boundary shear stress acting on bed-surface particles control patterns of bed load transport and channel evolution during varying stream discharges. At the reach scale a channel adjusts to imposed water and sediment supply through mutual interactions among channel form, local grain size, and local flow dynamics that govern bed mobility...

  4. Method for loading resin beds

    International Nuclear Information System (INIS)

    Notz, K.J.; Rainey, R.H.; Greene, C.W.; Shockley, W.E.

    1978-01-01

    An improved method of preparing nuclear reactor fuel by carbonizing a uranium loaded cation exchange resin provided by contacting a H+ loaded resin with a uranyl nitrate solution deficient in nitrate, comprises providing the nitrate deficient solution by a method comprising the steps of reacting in a reaction zone maintained between about 145 to 200 0 C, a first aqueous component comprising a uranyl nitrate solution having a boiling point of at least 145 0 C with a second aqueous component to provide a gaseous phase containing HNO 3 and a reaction product comprising an aqueous uranyl nitrate solution deficient in nitrate

  5. Bed-Load Dispersion: A Literature Review

    Science.gov (United States)

    2016-12-01

    ER D C/ CH L SR -1 6- 5 Coastal Inlets Research Program Bed-Load Dispersion: A Literature Review Co as ta l a nd H yd ra ul ic s La bo...ERDC/CHL SR-16-5 December 2016 Bed-Load Dispersion: A Literature Review James W. Lewis, Alejandro Sanchez, Travis Dahl, and Ian Floyd Coastal and...calculated at all nodes of each cross-section. 1.2 Objective The objective of this literature review is to prepare the conceptual founda- tion for the

  6. All-metal uranium bed loading system

    International Nuclear Information System (INIS)

    Eichman, C.C.

    1979-01-01

    The uranium bed processing system is essentially a vacuum system designed to transfer tritium gas from a large shipping container into small, portable containers called beds. The portable beds, designed to contain specific amounts of tritium or deuterium gas, are attached to various production systems for the purpose of hydriding occluder films in the production of neutron generators. The beds are constructed of stainless steel and contain uranium that is hydrided up to 50% capacity with tritium or deuterum gas. This technique not only makes it easy to load a bed, but also to recover surplus gas from a production system after the neutron generator hydriding process has been completed. The process development activities were directed toward solving and developing processing procedures for: (1) purifying the tritium gas; (2) reducing the protium gas; (3) removing helium (due to tritium decay) from the vacuum system; (4) eliminating hydrocarbon contamination; (5) increasing helium pumping speed with ion pumps; (6) providing multiple bed processing capability; (7) measuring pressure accurately; and (8) detect system leaks and obtain residual gas analyses of the system

  7. On the effect of segregation on intense bimodal bed load

    Directory of Open Access Journals (Sweden)

    Zrostlík Štěpán

    2017-01-01

    Full Text Available Open-channel two-phase flow above a granular mobile bed is studied experimentally and theoretically. In the two-phase flow, water serves as a carrying liquid for plastic grains transported as collisional contact load in the upper-stage plane bed regime. The investigation evaluates friction- and transport characteristics of the flow under the condition of intense collisional transport of grains and links them with the internal structure of the two-phase flow. The paper focusses on the effect of bimodal solids (mixed two fractions of grains of similar density and different size and shape on the flow characteristics and internal structure. Hence, experimental results obtained for the bimodal mixture are compared with results for individual grain fractions. The experiments show that the bimodal character of the transported solids affects the layered internal structure of the flow as a result of fraction segregation due primarily to gravity (kinetic sieving during transport. The segregation also affects the friction- and transport characteristics of intense bed load. In the paper, the effects are described and quantified.

  8. On the effect of segregation on intense bimodal bed load

    Science.gov (United States)

    Zrostlík, Štěpán; Matoušek, Václav

    Open-channel two-phase flow above a granular mobile bed is studied experimentally and theoretically. In the two-phase flow, water serves as a carrying liquid for plastic grains transported as collisional contact load in the upper-stage plane bed regime. The investigation evaluates friction- and transport characteristics of the flow under the condition of intense collisional transport of grains and links them with the internal structure of the two-phase flow. The paper focusses on the effect of bimodal solids (mixed two fractions of grains of similar density and different size and shape) on the flow characteristics and internal structure. Hence, experimental results obtained for the bimodal mixture are compared with results for individual grain fractions. The experiments show that the bimodal character of the transported solids affects the layered internal structure of the flow as a result of fraction segregation due primarily to gravity (kinetic) sieving during transport. The segregation also affects the friction- and transport characteristics of intense bed load. In the paper, the effects are described and quantified.

  9. A method for improving predictions of bed-load discharges to reservoirs

    Science.gov (United States)

    Lopes, V.L.; Osterkamp, W.R.; Bravo-Espinosa, M.

    2007-01-01

    Effective management options for mitigating the loss of reservoir water storage capacity to sedimentation depend on improved predictions of bed-load discharges into the reservoirs. Most predictions of bed-load discharges, however, are based on the assumption that the rates of bed-load sediment availability equal the transport capacity of the flow, ignoring the spatio-temporal variability of the sediment supply. This paper develops a semiquantitative method to characterize bed-load sediment transport in alluvial channels, assuming a channel reach is non-supply limited when the bed-load discharge of a given sediment particle-size class is functionally related to the energy that is available to transport that fraction of the total bed-load. The method was applied to 22 alluvial stream channels in the USA to determine whether a channel reach had a supply-limited or non-supply-limited bed-load transport regime. The non-supply-limited transport regime was further subdivided into two groups on the basis of statistical tests. The results indicated the pattern of bed-load sediment transport in alluvial channels depends on the complete spectrum of sediment particle sizes available for transport rather than individual particle-size fractions represented by one characteristic particle size. The application of the method developed in this paper should assist reservoir managers in selecting bed-load sediment transport equations to improve predictions of bed-load discharge in alluvial streams, thereby significantly increasing the efficiency of management options for maintaining the storage capacity of waterbodies. ?? 2007 Blackwell Publishing Asia Pty Ltd.

  10. Dynamics and mechanics of bed-load tracer particles

    Directory of Open Access Journals (Sweden)

    C. B. Phillips

    2014-12-01

    Full Text Available Understanding the mechanics of bed load at the flood scale is necessary to link hydrology to landscape evolution. Here we report on observations of the transport of coarse sediment tracer particles in a cobble-bedded alluvial river and a step-pool bedrock tributary, at the individual flood and multi-annual timescales. Tracer particle data for each survey are composed of measured displacement lengths for individual particles, and the number of tagged particles mobilized. For single floods we find that measured tracer particle displacement lengths are exponentially distributed; the number of mobile particles increases linearly with peak flood Shields stress, indicating partial bed load transport for all observed floods; and modal displacement distances scale linearly with excess shear velocity. These findings provide quantitative field support for a recently proposed modeling framework based on momentum conservation at the grain scale. Tracer displacement is weakly negatively correlated with particle size at the individual flood scale; however cumulative travel distance begins to show a stronger inverse relation to grain size when measured over many transport events. The observed spatial sorting of tracers approaches that of the river bed, and is consistent with size-selective deposition models and laboratory experiments. Tracer displacement data for the bedrock and alluvial channels collapse onto a single curve – despite more than an order of magnitude difference in channel slope – when variations of critical Shields stress and flow resistance between the two are accounted for. Results show how bed load dynamics may be predicted from a record of river stage, providing a direct link between climate and sediment transport.

  11. Variability of Bed Load Components in Different Hydrological Conditions

    Directory of Open Access Journals (Sweden)

    Hossein Kheirfam

    2017-04-01

    New hydrological insights: We found that the amount of the minimum, the mean and the maximum bed load were 3 × 10−8, 6.15 × 10−4± 7.17 × 10−4 and 4.38 × 10−3 kg s−1, respectively. The minimum, the mean, and the maximum discharge were also 60, 334 ± 215.56 and 780 l s−1, respectively. In low discharge conditions during summer, the fine grain sediments had the largest amount of bed load sediment. Coarse and medium-grained sediment transportation was higher in autumn and the early winter consistent with the occurrence of extreme rainfall and flood flows.

  12. Evaluation of ADCP apparent bed load velocity in a large sand-bed river: Moving versus stationary boat conditions

    Science.gov (United States)

    Jamieson, E.C.; Rennie, C.D.; Jacobson, R.B.; Townsend, R.D.

    2011-01-01

    Detailed mapping of bathymetry and apparent bed load velocity using a boat-mounted acoustic Doppler current profiler (ADCP) was carried out along a 388-m section of the lower Missouri River near Columbia, Missouri. Sampling transects (moving boat) were completed at 5- and 20-m spacing along the study section. Stationary (fixed-boat) measurements were made by maintaining constant boat position over a target point where the position of the boat did not deviate more than 3 m in any direction. For each transect and stationary measurement, apparent bed load velocity (vb) was estimated using ADCP bottom tracking data and high precision real-time kinematic (RTK) global positioning system (GPS). The principal objectives of this research are to (1) determine whether boat motion introduces a bias in apparent bed load velocity measurements; and (2) evaluate the reliability of ADCP bed velocity measurements for a range of sediment transport environments. Results indicate that both high transport (vb>0.6 m/s) and moving-boat conditions (for both high and low transport environments) increase the relative variability in estimates of mean bed velocity. Despite this, the spatially dense single-transect measurements were capable of producing detailed bed velocity maps that correspond closely with the expected pattern of sediment transport over large dunes. ?? 2011 American Society of Civil Engineers.

  13. The nature of the bed load transport in the mouth of the river to the non-tidal sea (the Vistula River, Poland)

    Science.gov (United States)

    Lisimenka, Aliaksandr; Zwoliński, Zbigniew; Rudowski, Stanisław

    2015-04-01

    layer thickness exceeds 3 m. In addition to, granulometry analysis indicates dominating of medium-grained sands, in average well sorted, with the small add mixture of coarsed-grained sand (mainly on the crest of dunes) and sandy muds (mainly in the hollows). Field and computer analyzes indicated on the hydrodynamic conditions of water discharge in the mouth of the Vistula River in the longitudinal and transverse profiles, variations of bed load facies and variations of morphodynamic zones in the river channel. Despite the large internal dynamics of the river channel, analyzes show the relative spatial stability of that channel, independent of seasonal variations. This demonstrates the inertial character (stable) of depositional environment in estuary section of the Vistula River.

  14. Literature Review for Texas Department of Transportation Research Project 0-4695: Guidance for Design in Areas of Extreme Bed-Load Mobility, Edwards Plateau, Texas

    National Research Council Canada - National Science Library

    Heitmuller, Franklin T; Asquith, William H; Fang, Xing; Thompson, David B; Wang, Keh-Han

    2005-01-01

    .... Major themes within the body of literature include deterministic sediment transport theory and equations, development of methods to measure and analyze fluvial sediment, applications and development...

  15. The relative contribution of near-bed vs. intragravel horizontal transport to fine sediment accumulation processes in river gravel beds

    Science.gov (United States)

    Casas-Mulet, Roser; Lakhanpal, Garima; Stewardson, Michael J.

    2018-02-01

    Understanding flow-sediment interactions is important for comprehending river functioning. Fine sediment accumulation processes, in particular, have key implications for ecosystem health. However, the amount of fines generated by intragravel flows and later accumulated in gravel streambeds may have been underestimated, as the hydraulic-related driving transport mechanisms in play are not clearly identified. Specifically, the relative contribution of fines from upper vs. lower sediment layers in gravel beds is not well understood. By recreating flooded and dewatered conditions in an experimental flume filled with natural sediment, we estimated such contributions by observing and collecting intragravel transported fines that were later accumulated into a void in the middle of the sediment matrix. Near-bed transport in the upper sediment layers (named Brinkman load) during flooded conditions accounted for most (90%) of the accumulated fines. Intragravel transport in the lower sediment layers (named Interstitial load) was the sole source of transport and accumulation during dewatered conditions with steeper hydraulic gradients. Interstitial load accounted for 10% of the total transport during flooded conditions. Although small, such estimations demonstrate that hydraulic-gradient transport in the lower sediment layers occurs in spite of the contradicting analytical assessments. We provide a case study to challenge the traditional approaches of assessing intragravel transport, and a useful framework to understand the origin and relative contribution of fine sediment accumulation in gravel beds. Such knowledge will be highly useful for the design of monitoring programs aiding river management, particularly in regulated rivers.

  16. Loading and Unloading Weaned Pigs: Effects of Bedding Types, Ramp Angle, and Bedding Moisture

    Directory of Open Access Journals (Sweden)

    Arlene Garcia

    2014-12-01

    Full Text Available The use of non-slip surfaces during loading and unloading of weaned pigs plays an important role in animal welfare and economics of the pork industry. Currently, the guidelines available only suggest the use of ramps below 20° to load and unload pigs. Three ramp angles (0°, 10° or 20°, five bedding materials (nothing, sand, feed, wood shavings or wheat straw hay, two moistures (dry or wet bedding; >50% moisture over two seasons (>23.9 °C summer, <23.9 °C winter were assessed for slips/falls/vocalizations (n = 6,000 pig observations. “Score” was calculated by the sum of slips, falls, and vocalizations. With the exception of using feed as a bedding, all beddings provided some protection against elevated slips, falls, and vocalizations (P < 0.01. Providing bedding reduced (P < 0.05 scores regardless of whether the bedding was dry or wet. Scores increased as the slope increased (P < 0.01. Provision of bedding, other than feed, at slopes greater than zero, decreased slips, falls and vocalizations. The total time it took to load and unload pigs was

  17. Unravelling the relative contribution of bed and suspended sediment load on a large alluvial river

    Science.gov (United States)

    Darby, S. E.; Hackney, C. R.; Parsons, D. R.; Leyland, J.; Aalto, R. E.; Nicholas, A. P.; Best, J.

    2017-12-01

    The world's largest rivers transport 19 billion tonnes of sediment to the coastal zone annually, often supporting large deltas that rely on this sediment load to maintain their elevation in the face of rising sea level, and to sustain high levels of agricultural productivity and biodiversity. However, the majority of estimates of sediment delivery to coastal regions pertain solely to the suspended fraction of the sediment load, with the bedload fraction often being neglected due to the difficulty in estimating bedload flux and the assumption that bedload contributes a minor (define suspended sediment rating curves using the inversion of acoustic return data from a series of acoustic Doppler current profiler surveys conducted through the Lower Mekong River in Cambodia, and into the bifurcating channels of the Mekong delta in Vietnam. Additionally, we detail estimates of bed-load sediment transport determined using repeat multibeam echo sounder surveys of the channel bed. By combining estimates of both fractions of the sediment load, we show the spatial and temporal contribution of bedload to the total sediment load of the Mekong and refine estimates of sediment transport to the Mekong delta. Our results indicate that the time-averaged suspended load transport rates for the Mekong River are 87 MT/yr, whilst bedload transport forms c. < 5% of the total sediment load within the Mekong River. Such estimates are integral to future channel management within this highly threatened river basin.

  18. Sediment transport primer: estimating bed-material transport in gravel-bed rivers

    Science.gov (United States)

    Peter Wilcock; John Pitlick; Yantao Cui

    2009-01-01

    This primer accompanies the release of BAGS, software developed to calculate sediment transport rate in gravel-bed rivers. BAGS and other programs facilitate calculation and can reduce some errors, but cannot ensure that calculations are accurate or relevant. This primer was written to help the software user define relevant and tractable problems, select appropriate...

  19. Universal characteristics of particle shape evolution by bed-load chipping

    Science.gov (United States)

    Sipos, András Árpád; Shaw, Sam; Sarti, Giovanni; Domokos, Gábor

    2018-01-01

    River currents, wind, and waves drive bed-load transport, in which sediment particles collide with each other and Earth’s surface. A generic consequence is impact attrition and rounding of particles as a result of chipping, often referred to in geological literature as abrasion. Recent studies have shown that the rounding of river pebbles can be modeled as diffusion of surface curvature, indicating that geometric aspects of impact attrition are insensitive to details of collisions and material properties. We present data from fluvial, aeolian, and coastal environments and laboratory experiments that suggest a common relation between circularity and mass attrition for particles transported as bed load. Theory and simulations demonstrate that universal characteristics of shape evolution arise because of three constraints: (i) Initial particles are mildly elongated fragments, (ii) particles collide with similarly-sized particles or the bed, and (iii) collision energy is small enough that chipping dominates over fragmentation but large enough that sliding friction is negligible. We show that bed-load transport selects these constraints, providing the foundation to estimate a particle’s attrition rate from its shape alone in most sedimentary environments. These findings may be used to determine the contribution of attrition to downstream fining in rivers and deserts and to infer transport conditions using only images of sediment grains. PMID:29670937

  20. The influence of sediment transport rate on the development of structure in gravel bed rivers

    Science.gov (United States)

    Ockelford, Annie; Rice, Steve; Powell, Mark; Reid, Ian; Nguyen, Thao; Tate, Nick; Wood, Jo

    2013-04-01

    Although adjustments of surface grain size are known to be strongly influenced by sediment transport rate little work has systematically explored how different transport rates can affect the development of surface structure in gravel bed rivers. Specifically, it has been well established that the transport of mixed sized sediments leads to the development of a coarser surface or armour layer which occurs over larger areas of the gravel bed. Armour layer development is known to moderate overall sediment transport rate as well as being extremely sensitive to changes in applied shear stress. However, during this armouring process a bed is created where, smaller gain scale changes, to the bed surface are also apparent such as the development of pebble clusters and imbricate structures. Although these smaller scale changes affect the overall surface grain size distribution very little their presence has the ability to significantly increase the surface stability and hence alter overall sediment transport rates. Consequently, the interplay between the moderation of transport rate as a function of surface coarsening at a larger scale and moderation of transport rate as a function of the development of structure on the bed surface at the smaller scale is complicated and warrants further investigation. During experiments a unimodal grain size distribution (σg = 1.30, D50 = 8.8mm) was exposed to 3 different levels of constant discharge that produced sediment transport conditions ranging from marginal transport to conditions approaching full mobility of all size fractions. Sediment was re-circulated during the experiments surface grain size distribution bed load and fractional transport rates were measured at a high temporal resolution such that the time evolution of the beds could be fully described. Discussion concentrates on analysing the effects of the evolving bed condition sediment transport rate (capacity) and transported grain size (competence). The outcome of this

  1. Measuring the Bed Load velocity in Laboratory flumes using ADCP and Digital Cameras

    Science.gov (United States)

    Conevski, Slaven; Guerrero, Massimo; Rennie, Colin; Bombardier, Josselin

    2017-04-01

    Measuring the transport rate and apparent velocity of the bedload is notoriously hard and there is not a certain technique that would obtain continues data. There are many empirical models, based on the estimation of the shear stress, but only few involve direct measurement of the bed load velocity. The bottom tracking (BT) mode of an acoustic Doppler current profiler (ADCP) has been used many times to estimate the apparent velocity of the bed load. Herein is the basic idea, to exploit the bias of the BT signal towards the bed load movement and to calibrate this signal with traditional measuring techniques. These measurements are quite scarce and seldom reliable since there are not taken in controlled conditions. So far, no clear confirmation has been conducted in laboratory-controlled conditions that would attest the assumptions made in the estimation of the apparent bed load velocity, nor in the calibration of the empirical equations. Therefore, this study explores several experiments under stationary conditions, where the signal of the ADCP BT mode is recorded and compared to the bed load motion recorded by digital camera videography. The experiments have been performed in the hydraulic laboratories of Ottawa and Bologna, using two different ADCPs and two different high resolution cameras. In total, more then 30 experiments were performed for different sediment mixtures and different hydraulic conditions. In general, a good match is documented between the apparent bed load velocity measured by the ADCP and the videography. The slight deviation in single experiments can be explained by gravel particles inhomogeneity, difficult in reproducing the same hydro-sedimentological conditions and the randomness of the backscattering strength.

  2. Establishing Bedding Requirements on Trailers Transporting Market Weight Pigs in Warm Weather

    Directory of Open Access Journals (Sweden)

    Rebecca Kephart

    2014-07-01

    Full Text Available During warm weather, incorrect bedding levels on a trailer transporting market weight pigs may result in heat stress, fatigue, and death. Two experiments were conducted in June and July of 2011; Experiment 1 used 80 loads (n = 13,887 pigs to determine the effects of two bedding levels (3 (68.1 kg or 6 bags (136.2 kg of wood shavings/trailer [each bag contained 22.7 kg, 0.2 m3] on pig measures (surface temperature, vocalizations, slips and falls, and stress signs. Experiment 2 used 131 loads (n = 22,917 pigs to determine the effects of bedding (3 vs. 6 bags on transport losses (dead, sum of dead- and euthanized- on arrival; non-ambulatory, sum of fatigued and injured; total transport losses sum of dead and non-ambulatory. Bedding did not affect surface temperature, vocalizations, or slips and falls (p = 0.58, p = 0.50, and p = 0.28, respectively. However, pigs transported on 6 bags/trailer had 1.5% more stress signs than pigs transported on 3 bags/trailer (p < 0.01. No differences were observed between bedding levels for non-ambulatory, dead, or total transport losses (p = 0.10, p = 0.67, and p = 0.34, respectively. Within the context of these experiments, bedding level did not result in deleterious effects on pig measures or transport losses. However, using more bedding may result in higher costs to the industry. Therefore, 3 bags of bedding/trailer may be used when transporting market weight pigs during warm weather in the Midwestern U.S.

  3. Bed load determination in Parana river by radioactive tracer technique

    International Nuclear Information System (INIS)

    Aoki, P.E.; Enokihara, C.T.; Rocca, H.C.C.; Bittencourt, A.V.L.

    1988-10-01

    Radioactive tracing technique with marked sand was employed to evaluate the bottom sediment drag of Parana river, near the future site for the ''Ilha Grande'' Dam in Guaira City (State of Parana). 198 Au radioisotope was employed and measurements had been performed for a period of fifteen days. A bed load rate of 952,3 t/day was obtained for a laminar layer of 0,33 m mean thickness and 1.65 m/day mean velocity. (author) [pt

  4. Fluvial sediment transport: Analytical techniques for measuring sediment load

    International Nuclear Information System (INIS)

    2005-07-01

    Sediment transport data are often used for the evaluation of land surface erosion, reservoir sedimentation, ecological habitat quality and coastal sediment budgets. Sediment transport by rivers is usually considered to occur in two major ways: (1) in the flow as a suspended load and (2) along the bed as a bed load. This publication provides guidance on selected techniques for the measurement of particles moving in both modes in the fluvial environment. The relative importance of the transport mode is variable and depends on the hydraulic and sedimentary conditions. The potential user is directed in the selection of an appropriate technique through the presentation of operating principles, application guidelines and estimated costs. Techniques which require laboratory analysis are grab sample, pump sample, depth sample, point integrated and radioactive tracers. Techniques which will continuously record data are optical backscattering, nuclear transmission, single frequency acoustic and laser diffraction

  5. The Importance of Splat Events to the Spatiotemporal Structure of Near-Bed Fluid Velocity and Bed Load Motion Over Bed Forms: Laboratory Experiments Downstream of a Backward Facing Step

    Science.gov (United States)

    Leary, K. C. P.; Schmeeckle, M. W.

    2017-12-01

    Flow separation/reattachment on the lee side of alluvial bed forms is known to produce a complex turbulence field, but the spatiotemporal details of the associated patterns of bed load sediment transported remain largely unknown. Here we report turbulence-resolving, simultaneous measurements of bed load motion and near-bed fluid velocity downstream of a backward facing step in a laboratory flume. Two synchronized high-speed video cameras simultaneously observed bed load motion and the motion of neutrally buoyant particles in a laser light sheet 6 mm above the bed at 250 frames/s downstream of a 3.8 cm backward facing step. Particle Imaging Velocimetry (PIV) and Acoustic Doppler Velocimetry (ADV) were used to characterize fluid turbulent patterns, while manual particle tracking techniques were used to characterize bed load transport. Octant analysis, conducted using ADV data, coupled with Markovian sequence probability analysis highlights differences in the flow near reattachment versus farther downstream. Near reattachment, three distinct flow patterns are apparent. Farther downstream we see the development of a dominant flow sequence. Localized, intermittent, high-magnitude transport events are more apparent near flow reattachment. These events are composed of streamwise and cross-stream fluxes of comparable magnitudes. Transport pattern and fluid velocity data are consistent with the existence of permeable "splat events," wherein a volume of fluid moves toward and impinges on the bed (sweep) causing a radial movement of fluid in all directions around the point of impingement (outward interaction). This is congruent with flow patterns, identified with octant analysis, proximal to flow reattachment.

  6. VO2 kinetics of constant-load exercise following bed-rest-induced deconditioning

    Science.gov (United States)

    Convertino, V. A.; Goldwater, D. J.; Sandler, H.

    1984-01-01

    Previous studies have shown that the oxygen uptake kinetics during exercise and recovery may be changed by alterations in work intensity, prior exercise, muscle group involvement, ambient conditions, posture, disease state, and level of physical conditioning. However, the effects of detraining on oxygen uptake kinetics have not been determined. The present investigation has the objective to determine the effects of deconditioning following seven days of continuous head-down bed rest on changes in steady-state oxygen uptake, O2 deficit, and recovery oxygen uptake during the performance of constant-load exercise. The obtained results may provide support for previous proposals that submaximal oxygen uptake was significantly reduced following bed rest. The major finding was that bed-rest deconditioning resulted in a reduction of total O2 transport/utilization capacity during the transient phase of upright but not supine exercise.

  7. The Impact of Urbanization on Temporal Changes in Sediment Transport in a Gravel Bed Channel in Southern Ontario, Canada

    Science.gov (United States)

    Plumb, B. D.; Annable, W. K.; Thompson, P. J.; Hassan, M. A.

    2017-10-01

    A field investigation has been undertaken to characterize the event-based bed load transport dynamics of a highly urbanized gravel bed stream. A combination of direct bed load and tracer particle measurements were taken over a 3 year period during which time approximately 30 sediment mobilizing events occurred. Sediment transport measurements were used to calibrate a fractional bed load transport model and combined with hydrometric data which represent four different land use conditions (ranging from rural to highly urbanized) to analyze the differences in discharge magnitude and frequency and its impact on sediment transport. Fractional transport analysis of the bed load measurements indicates that frequent intermediate discharge events can mobilize sand and fine gravel to an approximate equally mobile condition, however, the transport rates at these discharges exhibit greater variability than at discharges above the bankfull discharge. Path lengths of the coarse fraction, measured using tracer clasts, are insensitive to peak discharge, and instead transport at distances less than those reported in other gravel bed channels, which is attributed to the shorter duration discharge events common to urban streams. The magnitude-frequency analysis reveals that the frequency, time, and volume of competent sediment mobilizing events are increasing with urbanization. Variability in effective discharges suggests that a range of discharges, spanning between frequent, low magnitude events to less frequent, high magnitude events are geomorphically significant. However, trends in the different land use scenarios suggest that urbanization is shifting the geomorphic significance toward more frequent, lower magnitude events.

  8. Sediment and Hydraulic Measurements with Computed Bed Load on the Missouri River, Sioux City to Hermann, 2014

    Science.gov (United States)

    2017-05-01

    profiler, suspended sediment, and bed material samples were collected for each site visit. As requested by the Districts, all units are in English ...CHL TR-17-8 203 site. The data in these graphs were provided by written communication with David Heimann, Hydrologist at the USGS, Missouri Water...in English units. In addition to quantifying all the intended data types listed above, bed-load transport values were computed for all sites and all

  9. Deterministic and stochastic dynamics of bed load tracer particles in a coarse grained river

    Science.gov (United States)

    Phillips, C. B.; Martin, R. L.; Jerolmack, D. J.

    2012-12-01

    Understanding the mechanics of a single coarse sediment particle, and the mechanics of sediment transport at the flood scale, is critical to linking event scale bed load transport rates to annual bed load fluxes. We present research on the dynamics of coarse sediment tracer particles tagged with passive radio transponder tags, observing motion resulting from individual floods and the cumulative transport over many floods spanning two years, in the Mameyes River in the Luquillo Mountains of Puerto Rico. This region presents an ideal study area due to the high frequency of coarse sediment mobilizing events, which allows us to field test the applicability of recently-proposed deterministic and stochastic theories for particle motion. Data for each flood are composed of (1) measured 'flight' lengths for each transported particle, (2) the fraction of tagged particles mobilized, and (3) high-resolution river stage measurements. At the single flood scale, measured tracer particle flight lengths are exponentially distributed, and modal flight lengths scale linearly with excess shear velocity. This is in quantitative agreement with recent theory and laboratory experiments, suggesting that moving particles' velocity is determined by momentum balance with the fluid. The fraction of mobile particles per event increases rapidly with flood stage, creating a logistic-like curve whose inflection point is used to empirically define the threshold of motion. This finding is in contrast to the linear relation observed in small-scale experiments and predicted from momentum balance between sediment and fluid; we use a particle Stokes number argument to suggest that a collision cascade from grain-grain interactions is responsible for the nonlinear relation between mobile fraction and fluid stress, in dynamical equivalence with aeolian sand transport. To examine particle dispersion and relate it to transport mechanics, it is necessary to remove the time over which the fluid stress is

  10. Pressurized fluidized-bed combustion part-load behavior. Volume I. Summary report

    Energy Technology Data Exchange (ETDEWEB)

    Roberts, A. G.; Pillai, K. K.; Raven, P.; Wood, P.

    1981-09-01

    Tests performed during 1980 to determine the part-load characteristics of a pressurized fluidized-bed combustor for a combined-cycle power plant and to examine its behavior during load changing are discussed. Part-load operation was achieved by varying the bed temperature by amounts between 200 to 300/sup 0/F and the bed depth from between 9 and 10 ft at rates varying between 0.2 ft/min and 0.5 ft/min. The performance at part-load steady-state conditions and during transient conditions is reported with information on combustion efficiency (99% at full-load with 9 ft bed depth and 1650/sup 0/F bed temperature; 95% with 4 ft depth and 1390/sup 0/F); sulfur retention (95/sup 0/ at full load to 80% at low bed depth and low bed temperature); sulfur emissions (no definitive results); NO/sub x/ emissions (tendency for increase as bed temperature was reduced); alkali emissions (no bed temperature effect detected); and heat transfer. It was demonstrated that load can be altered in a rapid and controlled manner by changing combinations of bed depth temperature and pressure. The most important practical change was the reduction in O/sub 2/ concentration which occurred when the bed height was increased at a rapid rate. The extra energy required to reheat the incoming bed material resulted (in the most extreme case) in a temporary drop in excess air from 65% to 12%. In a full-scale plant the loss of heat from the stored bed material would be much lower and the excess air trough when increasing load would not be as pronounced. Nevertheless, it seems prudent to design full-scale plant for a full load excess air of not less than about 50% when using bed depth as a load control parameter.

  11. Coupling Solute and Fine Particle Transport with Sand Bed Morphodynamics within a Field Experiment

    Science.gov (United States)

    Phillips, C. B.; Ortiz, C. P.; Schumer, R.; Jerolmack, D. J.; Packman, A. I.

    2017-12-01

    Fine suspended particles are typically considered to pass through streams and rivers as wash load without interacting with the bed, however experiments have demonstrated that hyporheic flow causes advective exchange of fine particles with the stream bed, yielding accumulation of fine particle deposits within the bed. Ultimately, understanding river morphodynamics and ecosystem dynamics requires coupling both fine particle and solute transport with bed morphodynamics. To better understand the coupling between these processes we analyze a novel dataset from a controlled field experiment conducted on Clear Run, a 2nd order sand bed stream located within the North Carolina coastal plain. Data include concentrations of continuously injected conservative solutes and fine particulate tracers measured at various depths within the stream bed, overhead time lapse images of bed forms, stream discharge, and geomorphological surveys of the stream. We use image analysis of bed morphodynamics to assess exchange, retention, and remobilization of solutes and fine particles during constant discharge and a short duration experimental flood. From the images, we extract a time series of bedform elevations and scour depths for the duration of the experiment. The high-resolution timeseries of bed elevation enables us to assess coupling of bed morphodynamics with both the solute and fine particle flux during steady state mobile bedforms prior to the flood and to changing bedforms during the flood. These data allow the application of a stochastic modeling framework relating bed elevation fluctuations to fine particle residence times. This combined experimental and modeling approach ultimately informs our ability to predict not only the fate of fine particulate matter but also associated nutrient and carbon dynamics within streams and rivers.

  12. Desulfurization Sorbents for Transport-Bed Applications

    International Nuclear Information System (INIS)

    Gupta, Raghubir P.; Turk, Brian S.; Vierheilig, Albert A.

    1997-01-01

    This project extends the prior work on the development of fluidizable zinc titanate particles using a spray-drying technique to impart high reactivity and attrition resistance. The specific objectives are: (1) To develop highly reactive and attrition-resistant zinc titanate sorbents in 40- to 150-(micro)m particle size range for transport reactor applications; (2) To transfer sorbent production technology to private sector; and (3) To provide technical support to Sierra Pacific Clean Coal Technology Demonstration plant and FETC's Hot-Gas Desulfurization Process Development Unit (PDU), both employing a transport reactor system

  13. Product removal and solids transport from fluidized-bed calciners

    International Nuclear Information System (INIS)

    Grimmett, E.S.; Munger, D.H.

    1978-09-01

    Methods of removing the solid product from pilot-plant and production fluidized-bed calciners, and transporting product to underground storage vaults are reported here. Testing of dense-phase solids transport systems in test loops during development of a 15-cm-diam. and 30-cm-diam. calciner are described. A lean-phase solid transport system is used with the Waste Calcining Facility. The results of some recent tests done in a lean-phase transport system connected to the 30-cm-diam. calciner are included in this report

  14. Bed load size distribution and flow conditions in a high mountain catchment of Central Pyrenees

    OpenAIRE

    Martínez Castroviejo, Ricardo

    1990-01-01

    The bed load size distribution caused by different types of flow are compared in a high mountain catchment located in the upper Gallego river basin (Central Spanish’ Pyrenees). Three kinds of hydrologic events could be defined: those triggered by heavy autumn rainfalls, those originated by isolated summer rainstorms and those promoted by snowmelting. Each one is characterized by a peculiar bed load size distribution. Thus, it could be demonstrated that the coarser fractions, above 30 mm in di...

  15. Bed load size distribution and flow conditions in a high mountain catchment of Central Pyrenees

    Directory of Open Access Journals (Sweden)

    Martínez-Castroviejo, Ricardo

    1990-06-01

    Full Text Available The bed load size distribution caused by different types of flow are compared in a high mountain catchment located in the upper Gallego river basin (Central Spanish’ Pyrenees. Three kinds of hydrologic events could be defined: those triggered by heavy autumn rainfalls, those originated by isolated summer rainstorms and those promoted by snowmelting. Each one is characterized by a peculiar bed load size distribution. Thus, it could be demonstrated that the coarser fractions, above 30 mm in diameter, are up to six times more abundant, in percentage of total weight, in transports caused by heavy rainfalls than in the material collected after snowmelt flows. In its turn, bed load mobilized by snowmelt flows is mainly composed by medium and fine gravel, from 2 to 8 mm. These may amount up to 60 % of total weight of bed load. The reasons for these so different size distributions are discussed.

    [es] En una cuenca de alta montaña localizada en el alto valle del río Gallego (Pirineo central se comparan las distribuciones por tamaños de los acarreos movilizados por diferentes tipos de caudal. Tres tipos de eventos hidrológicos han podido ser caracterizados: los ocasionados por intensas lluvias de otoño, los originados por tormentas estivales aisladas y los producidos por la fusión de la nieve acumulada durante el invierno. Se concluye que cada uno de ellos lleva asociada una distribución por tamaños típica de la carga de fondo. Así, se ha comprobado que las fracciones más gruesas consideradas -superiores a los 30 mm de diámetro- son hasta seis veces más abundantes -en porcentaje sobre el peso total- en las exportaciones causadas por lluvias de gran intensidad que en las generadas por caudales de fusión. A su vez, las descargas ocasionadas por la fusión arrastran principalmente gravas de calibre medio y fino -entre 2y8 mm- que llegan a suponer el 60 % en peso del volumen movilizado. Este artículo discute las razones que provocan

  16. Calculations of Bed-Material Transport, Chetco River, Oregon

    Science.gov (United States)

    Anderson, S.; Wallick, R.; Cannon, C.; O'Connor, J. E.

    2009-12-01

    The Chetco River drains 914 square kilometers of the Klamath Mountains in far southwestern Oregon. The lower 18 kilometers of the river are flanked by large and abundant gravel bars, which have been commercially mined for aggregate during most of the last century. Increasing concern regarding the impact of this mining on aquatic habitats motivated an assessment of historical channel change and sediment transport rates along this lower reach. A key component of this research was estimating bed-material transport through the application of sediment transport equations at multiple locations along the study reach. Flow hydraulics were estimated with a 1-D hydraulic model constructed in HEC-RAS, using a combination of LiDAR and bathymetric surveys to characterize the valley morphology. Once calibrated to USGS rating curves, low flow water surfaces, and several high flow photos, this model allowed us to calculate energy slopes for a given cross section at a variety of flows. These flow-energy slope pairs, along with cross sections and sediment data collected from surface pebble counts, were then applied to a number of different modern bedload transport equations. This process was facilitated by the Bedload Assessment in Gravel-bedded Streams Excel macro, or BAGS, which allows users to quickly apply multiple transport equations using a single set of inputs (Pitlick et al., 2009). A review of the literature, along with tests of internal consistency and comparisons to direct bedload measurements taken in the winter of 2008-09, led us to choose the Parker (1991) and Wilcock-Crowe (2003) equations as the two most applicable to the Chetco River. Sediment transport-flow curves for both equations were calculated for seven cross sections spanning the study area. For each of these cross sections, we estimated annual transport fluxes using derived transport rating curves in conjunction with unit flow data from a USGS gage at the upstream end of study reach, with data extending back

  17. Bed load tracer mobility in a mixed bedrock/alluvial channel

    Science.gov (United States)

    Ferguson, R. I.; Sharma, B. P.; Hodge, R. A.; Hardy, R. J.; Warburton, J.

    2017-04-01

    The presence of bare or partially covered rock in an otherwise alluvial river implies a downstream change in transport capacity relative to supply. Field investigations of this change and what causes it are lacking. We used two sets of magnet-tagged tracer clasts to investigate bed load transport during the same sequence of floods in fully alluvial, bare rock, and partial-cover reaches of an upland stream. High-flow shear stresses in different reaches were calculated by using stage loggers. Tracers seeded in the upstream alluvial channel moved more slowly than elsewhere until the frontrunners reached bare rock and sped up. Tracers seeded on bare rock moved rapidly off it and accumulated just upstream from, and later in, a partial-cover zone with many boulders. The backwater effect of the boulder-rich zone is significant in reducing tracer mobility. Tracer movement over full or partial sediment cover was size selective but dispersion over bare rock was not. Along-channel changes in tracer mobility are interpreted in terms of measured differences in shear stress and estimated differences in threshold stress.

  18. Direct Observation of Heavy-Tailed Storage Times of Bed Load Tracer Particles Causing Anomalous Superdiffusion

    Science.gov (United States)

    Bradley, D. Nathan

    2017-12-01

    A consensus has formed that the step length distribution of fluvial bed load is thin tailed and that the observed anomalous superdiffusion of bed load tracer particles must arise from heavy-tailed resting times. However, heavy-tailed resting times have never been directly observed in the field over multiple floods. Using 9 years of data from a large bed load tracer experiment, I show that the spatial variance of the tracer plume scales faster than linearly with integrated excess stream power, indicating anomalous superdiffusion. The superdiffusion is caused by a heavy-tailed distribution of observed storage times that is fit with a truncated Pareto distribution with a tail parameter that is predicted by anomalous diffusion theory. The heavy-tailed distribution of storage times causes the tracer virtual velocity to slow over time, indicated by a sublinear increase in the mean displacement that is predicted by the storage time distribution tail parameter.

  19. Bed-material entrainment and associated transportation infrastructure problems in streams of the Edwards Plateau, central Texas

    Science.gov (United States)

    Heitmuller, Franklin T.; Asquith, William H.

    2008-01-01

    The Texas Department of Transportation commonly builds and maintains low-water crossings (LWCs) over streams in the Edwards Plateau in Central Texas. LWCs are low-height structures, typically constructed of concrete and asphalt, that provide acceptable passage over seasonal rivers or streams with relatively low normal-depth flow. They are designed to accommodate flow by roadway overtopping during high-flow events. The streams of the Edwards Plateau are characterized by cobble- and gravel-sized bed material and highly variable flow regimes. Low base flows that occur most of the time occasionally are interrupted by severe floods. The floods entrain and transport substantial loads of bed material in the stream channels. As a result, LWCs over streams in the Edwards Plateau are bombarded and abraded by bed material during floods and periodically must be maintained or even replaced.

  20. Bed topography and sand transport responses to a step change in discharge and water depth

    Science.gov (United States)

    Ephemeral streams with sand and gravel beds may inherit bed topography caused by previous flow events, resulting in bed topography that is not in equilibrium with flow conditions, complicating the modeling of flow and sediment transport. Major flow events, resulting from rainfall with high intensity...

  1. Modified Laursen Method for Estimating Bed-Material Sediment Load

    Science.gov (United States)

    1993-10-01

    Mr. 1Tnomas. At the time of publication of this report, Director of WES was Dr. Robert W. Whalin. Commander was COL Bruce K. Howard, EN . iv Conversion...GOrade near Bernalillo, New Mexico Middle Loop River at Dunning. Nebraska Niobrara River near Cody, Nebraska Arkansas River at Dardandle and Morrilton...comparable to results of other sediment load computation procedures. CWp 5 Appkaik of Modaed Laurmn FundconA RWtonsNp 13 IGO- 060OMM UM.TO.AM F~gur S

  2. Synergism Analysis of Bedding Slope with Piles and Anchor Cable Support under Sine Wave Vehicle Load

    Directory of Open Access Journals (Sweden)

    Li Dan-Feng

    2016-01-01

    Full Text Available Slope instability under dynamic load is the technical difficulty in the engineering; the evaluation of slope stability under dynamic load and the control of dynamic load is particularly important. In this paper, taking the right side slope of K27+140 m~380 m typical section (K27 slope for short in Chongqing Fuling-Fengdu-Shizhu expresses highway as an example to calculate and analyze. The K27 slope is under sinusoidal vehicle load and supported by anchor cable and antislide pile to resist downslide strength; at the same time, the combined effect of them is studied. Three-dimensional finite element methodology (FEM is used to simulate the bedding slope with piles and anchor cable support; furthermore, the eigenvalue can be obtained. In order to reduce error of the elastic boundary conditions caused by the reflection effect of wavelengths, the combination of Lysmer surface viscous boundary and traditional ground support boundaries is utilized to analyze and calculate the time-histories during bedding slope under dynamic load. The dynamic response of pile anchor support to resist sliding force is obtained. The concept of the pile anchor supporting coordinate interval is put forward. Furthermore, it is verified that the pile anchor supporting coordinate interval can be used to evaluate the stability of the slope under dynamic load and provide a new method for the control of the dynamic load.

  3. Solid phase transport in series fluidised bed reactors

    International Nuclear Information System (INIS)

    Hayes, M.R.

    1980-01-01

    In a multistage counter-current fluidised bed column, fluidised bed material is recycled within each stage and a fraction is continuously withdrawn to the next lower stage at a rate dependent only on the rate of removal of the fluidised bed material from the base of the column. It has a particular application to the ion exchange treatment of liquids containing suspended solids, for example leach solutions from uranium ores. (author)

  4. Biomass gasification using nickel loaded brown coal char in fluidized bed gasifier at relatively low temperature

    Energy Technology Data Exchange (ETDEWEB)

    Le, D.D.; Xiao, X.B.; Morishita, K.; Takarada, T. [Gunma University, Gumma (Japan)

    2009-07-01

    Our work focuses on developing nickel loaded brown coal char as a new catalyst to decompose tar and to enhance quality of product gas delivered from woody biomass pyrolysis at relatively low temperatures of 823 K and 923 K. It is carried out in two-stage fixed-bed reactor and a lab scale fluidized bed gasifier (FBG) under various conditions. Inside of gasifier is constructed by two beds, the primary one is a fluidized bed with sand. and the second one is a catalyst bed. The catalyst bed is used to evaluate and to compare catalytic activity between the new catalyst and a conventional Ni/Al{sub 2}O{sub 3} catalyst. The new catalyst is prepared by ion exchange method, dried at 380 K in nitrogen for 24 h, and is then calcined at 923 K in nitrogen for 90 min. The temperature as a function of gas yield and the effect of catalysts on gas yield in presence and absence of steam are investigated in this study. The new catalyst has shown high catalytic activity and stable activity and given the high quality of product gas in presence of steam.

  5. Technical and economic assessment of fluidized-bed-augmented compressed-air energy-storage system: system load following capability

    Energy Technology Data Exchange (ETDEWEB)

    Lessard, R.D.; Blecher, W.A.; Merrick, D.

    1981-09-01

    The load-following capability of fluidized bed combustion-augmented compressed air energy storage systems was evaluated. The results are presented in two parts. The first part is an Executive Summary which provides a concise overview of all major elements of the study including the conclusions, and, second, a detailed technical report describing the part-load and load following capability of both the pressurized fluid bed combustor and the entire pressurized fluid bed combustor/compressed air energy storage system. The specific tasks in this investigation were to: define the steady-state, part-load operation of the CAES open-bed PFBC; estimate the steady-state, part-load performance of the PFBC/CAES system and evaluate any possible operational constraints; simulate the performance of the PFBC/CAES system during transient operation and assess the load following capability of the system; and establish a start-up procedure for the open-bed PFBC and evaluate the impact of this procedure. The conclusions are encouraging and indicate that the open-bed PFBC/CAES power plant should provide good part-load and transient performance, and should have no major equipment-related constraints, specifically, no major problems associated with the performance or design of either the open-end PFBC or the PFBC/CAES power plant in steady-state, part-load operation are envisioned. The open-bed PFBC/CAES power plant would have a load following capability which would be responsive to electric utility requirements for a peak-load power plant. The open-bed PFBC could be brought to full operating conditions within 15 min after routine shutdown, by employing a hot-start mode of operation. The PFBC/CAES system would be capable of rapid changes in output power (12% of design load per minute) over a wide output power range (25% to 100% of design output). (LCL)

  6. Appraisal of soft computing techniques in prediction of total bed material load in tropical rivers

    Science.gov (United States)

    Chang, C. K.; Azamathulla, H. Md; Zakaria, N. A.; Ghani, A. Ab

    2012-02-01

    This paper evaluates the performance of three soft computing techniques, namely Gene-Expression Programming (GEP) (Zakaria et al 2010), Feed Forward Neural Networks (FFNN) (Ab Ghani et al 2011), and Adaptive Neuro-Fuzzy Inference System (ANFIS) in the prediction of total bed material load for three Malaysian rivers namely Kurau, Langat and Muda. The results of present study are very promising: FFNN ( R 2 = 0.958, RMSE = 0.0698), ANFIS ( R 2 = 0.648, RMSE = 6.654), and GEP ( R 2 = 0.97, RMSE = 0.057), which support the use of these intelligent techniques in the prediction of sediment loads in tropical rivers.

  7. Turbulent flow and sand transport over a cobble bed in a laboratory flume

    Science.gov (United States)

    The turbulence structure of flow over rough beds and its interaction with fine sediments in the bed are important for efforts to predict sediment transport downstream of dams. The advanced age and impending decommissioning of many dams have brought increased attention to the fate of sediments stored...

  8. Probability distributions of bed load particle velocities, accelerations, hop distances, and travel times informed by Jaynes's principle of maximum entropy

    Science.gov (United States)

    Furbish, David; Schmeeckle, Mark; Schumer, Rina; Fathel, Siobhan

    2016-01-01

    We describe the most likely forms of the probability distributions of bed load particle velocities, accelerations, hop distances, and travel times, in a manner that formally appeals to inferential statistics while honoring mechanical and kinematic constraints imposed by equilibrium transport conditions. The analysis is based on E. Jaynes's elaboration of the implications of the similarity between the Gibbs entropy in statistical mechanics and the Shannon entropy in information theory. By maximizing the information entropy of a distribution subject to known constraints on its moments, our choice of the form of the distribution is unbiased. The analysis suggests that particle velocities and travel times are exponentially distributed and that particle accelerations follow a Laplace distribution with zero mean. Particle hop distances, viewed alone, ought to be distributed exponentially. However, the covariance between hop distances and travel times precludes this result. Instead, the covariance structure suggests that hop distances follow a Weibull distribution. These distributions are consistent with high-resolution measurements obtained from high-speed imaging of bed load particle motions. The analysis brings us closer to choosing distributions based on our mechanical insight.

  9. PTC test bed upgrades to provide ACSES testing support capabilities at transportation technology center.

    Science.gov (United States)

    2015-06-01

    FRA Task Order 314 upgraded the Positive Train Control (PTC) Test Bed at the Transportation Technology Center to support : testing of PTC systems, components, and related equipment associated with the Advanced Civil Speed Enforcement System : (ACSES)...

  10. Leaf transport in mimic mangrove forests and seagrass beds

    NARCIS (Netherlands)

    Gillis, L.G.; Bouma, T.J.; Kiswara, W.; Ziegler, A.D.; Herman, P.M.J.

    2014-01-01

    Mangrove forests and seagrass beds are thought to exchange particulate organic material, especially in the form of leaves. However, relatively little is known about the trapping capacity of mangrove above-ground roots and seagrass plants for leaf segments. We aimed to identify the major factors

  11. Predicting Coarse Sediment Transport from Patchy Beds in Ephemeral Channels

    Science.gov (United States)

    2012-04-01

    basin fill of Plio-Pleistocene plutonic or volcanic clasts approaching 900 m in thickness. Surficial ERDC/GSL TR-12-17 7 sediments were likely...flow velocity, D84 is grain size in which 84% of the channel bed grains are finer. The variable a is a channel shape factor defined as h R a D

  12. Temperature and Relative Humidity Inside Trailers During Finishing Pig Loading and Transport in Cold and Mild Weather

    Directory of Open Access Journals (Sweden)

    John McGlone

    2014-09-01

    Full Text Available The effect of bedding levels and trailer compartment on internal trailer temperature and relative humidity (RH during loading and transport of finishing pigs was evaluated in cold and mild weather. Three levels of bedding were used in each experiment: 0.6 m3, 1.2 m3, and 2.4 m3. In mild weather, internal temperatures were lower when 1.2 m3 or 2.4 m3 of bedding were used during loading and transport compared to 0.6 m3 (P < 0.05. Internal trailer temperature increased in a quadratic fashion in the top front compartment when 1.2 m3 was used (P < 0.05, and in a linear fashion in the top rear compartment when 2.4 m3 were used in cold weather (P < 0.05. In mild weather, temperature increased linearly in the top front compartment with heavy bedding levels. Relative humidity increased in a linear fashion in the top front compartment with 0.6 m3, bottom front with 1.2 m3, and top front with 1.2 m3 in cold weather (P < 0.05. In general, temperature and RH increased as bedding levels increased in both cold and mild temperatures. Excess bedding can absorb more moisture, resulting in transport loss and decreased animal welfare.

  13. Establishing Bedding Requirements during Transport and Monitoring Skin Temperature during Cold and Mild Seasons after Transport for Finishing Pigs.

    Science.gov (United States)

    McGlone, John; Johnson, Anna; Sapkota, Avi; Kephart, Rebecca

    2014-05-21

    The broad aim of this study was to determine whether bedding level in the transport trailer influenced pig performance and welfare. Specifically, the objective was to define the bedding requirements of pigs during transportation in commercial settings during cold and mild weather. Animals (n = 112,078 pigs on 572 trailers) used were raised in commercial finishing sites and transported in trailers to commercial processing plants. Dead on arrival (DOA), non-ambulatory (NA), and total dead and down (D&D) data were collected and skin surface temperatures of the pigs were measured by infrared thermography. Data were collected during winter (Experiment 1) and fall/spring (Experiment 2). Total D&D percent showed no interaction between bedding level and outside air temperature in any experiments. Average skin surface temperature during unloading increased with outside air temperature linearly in both experiments (P transport.

  14. Influence of tube and particle diameter on heat transport in packed beds

    NARCIS (Netherlands)

    Borkink, J.G.H.; Borkink, J.G.H.; Westerterp, K.R.

    1992-01-01

    Influence of the tube and particle diameter and shape, as well as their ratio, on the radial heat transport in packed beds has been studied. Heat transport experiments were performed with four different packings in three wall-cooled tubes, which differed in inner diameter only. Experimental values

  15. Investigation on energy storage and quick load change control of subcritical circulating fluidized bed boiler units

    International Nuclear Information System (INIS)

    Gao, Mingming; Hong, Feng; Liu, Jizhen

    2017-01-01

    Highlights: • The model of energy storage of subcritical CFB boilers is established. • The capacity and increment rate of heat storage are quantified. • A novel load control strategy is proposed to improve the quick load change ability. • An application on the 300 MW CFB unit proves the load change rate to 5–8 MW/min. - Abstract: The energy storage of circulating fluidized bed (CFB) boilers on fuel side cannot be ignored due to the special combustion type different from pulverized coal boilers. The sizable energy storage makes it possible for CFB units to enhance the quick load change ability and to increase the scale of new energy power connected into grid. Through mechanism analysis, the model of energy storage of subcritical CFB boilers has been established for the first time. Then by the project practice, the quantitative analysis is demonstrated for the capacity and control characteristics of energy storage on fuel side and steam water side. Based on the control characteristics and the transformation of the energy storage, a coordinated control system (CCS) control strategy named advanced energy balance (AEB) is designed to shorten the response time through the use of energy storage and to accelerate the load change speed of subcritical CFB units. Finally, a case study on a 300 MW CFB unit proves the feasibility of the proposed control strategy.

  16. Sediment transport capacity of concentrated flows on steep loessial slope with erodible beds.

    Science.gov (United States)

    Xiao, Hai; Liu, Gang; Liu, Puling; Zheng, Fenli; Zhang, Jiaqiong; Hu, Feinan

    2017-05-24

    Previous research on sediment transport capacity has been inadequate and incomplete in describing the detachment and transport process of concentrated flows on slope farmlands during rill development. An indoor concentrated flow scouring experiment was carried out on steep loessial soil slope with erodible bed to investigate the sediment transport capacity under different flow rates and slope gradients. The results indicated that the sediment transport capacity increases with increasing flow rate and slope gradient, and these relationships can be described by power functions and exponential functions, respectively. Multivariate, nonlinear regression analysis showed that sediment transport capacity was more sensitive to slope gradient than to flow rate, and it was more sensitive to unit discharge per unit width than to slope gradient for sediment transport capacity in this study. When similar soil was used, the results were similar to those of previous research conducted under both erodible and non-erodible bed conditions. However, the equation derived from previous research under non-erodible bed conditions with for river bed sand tends to overestimate sediment transport capacity in our experiment.

  17. Continuous separation of protein loaded nanoparticles by simulated moving bed chromatography.

    Science.gov (United States)

    Satzer, Peter; Wellhoefer, Martin; Jungbauer, Alois

    2014-07-04

    For scale up and efficient production of protein loaded nanoparticles continuous separation by size exclusion chromatography in simulated moving bed (SMB) mode helps do reduce unbound protein concentration and increase yields for perfectly covered particles. Silica nanoparticles were loaded with an excess of beta casein or bovine serum albumin (BSA) and the loaded particles purified by size exclusion chromatography using Sephacryl300 as stationary phase in a four zone SMB. We determined our working points for the SMB from batch separations and the triangle theory described by Mazzotti et al. with an SMB setup of one Sephacryl300 26/70mm column per zone with switch times of 5min for BSA and 7min for beta casein. In the case of BSA the Raffinate contained loaded nanoparticles of 63% purity with 98% recovery and the extract was essentially particle free (95% purity). We showed that the low purity of the Raffinate was only due to BSA multimers present in the used protein solution. In the case of beta casein where no multimers are present we achieved 89% purity and 90% recovery of loaded nanoparticles in the Raffinate and an extract free of particles (92% purity). Using a tangential flow filtration unit with 5kDa cutoff membrane we proved that the extract can be concentrated for recycling of protein and buffer. The calculated space-time-yield for loaded nanoparticles was 0.25g of loaded nanoparticles per hour and liter of used resin. This proves that the presented process is suitable for large scale production for industrial purposes. Copyright © 2014 The Authors. Published by Elsevier B.V. All rights reserved.

  18. Auto Carrier Transporter Loading and Unloading Improvement

    National Research Council Canada - National Science Library

    Miller, Brian

    2003-01-01

    .... Any reduction in time and energy will result in a significant savings of money. The intent of this research is to develop an algorithm to solve the Auto Carrier Transport Pickup and Delivery Problem...

  19. Missouri S&T hydrogen transportation test bed equipment & construction.

    Science.gov (United States)

    2010-08-01

    Investments through the National University Transportation Center at Missouri University of Science and Technology have really scored on the Centers mission areas and particularly Transition-state fuel vehicle infrastructure leading to a hydrogen ...

  20. Sediment and Hydraulic Measurements with Computed Bed Load on the Missouri River, Sioux City to Hermann, 2014

    Science.gov (United States)

    2017-05-01

    large sand bed river, with seven sites representing increasingly larger flows along the river length. The data set will be very useful for additional...24 Table 11. Suspended sediment load distributed by grain size and soil type – April 30, 2014. ............. 28 Table 12. Suspended sediment...load distributed by grain size and soil type – June 5, 2014. .............. 28 Table 13. Suspended sediment load distributed by grain size and soil type

  1. Geologic and physiographic controls on bed-material yield, transport, and channel morphology for alluvial and bedrock rivers, western Oregon

    Science.gov (United States)

    O'Connor, James E.; Mangano, Joseph F.; Anderson, Scott A.; Wallick, J. Rose; Jones, Krista L.; Keith, Mackenzie K.

    2014-01-01

    The rivers of western Oregon have diverse forms and characteristics, with channel substrates ranging from continuous alluvial gravel to bare bedrock. Analysis of several measurable morphologic attributes of 24 valley reaches on 17 rivers provides a basis for comparing nonalluvial and alluvial channels. Key differences are that alluvial reaches have greater bar area, greater migration rates, and show systematic correlation among variables relating grain size to bed-material transport capacity. We relate these differences between channel types to bed-material transport rates as derived from a coupled regional analysis of empirical sediment yield measurements and physical experiments of clast attrition during transport. This sediment supply analysis shows that overall bed-material transport rates for western Oregon are chiefly controlled by (1) lithology and basin slope, which are the key factors for bed-material supply into the stream network, and (2) lithologic control of bed-material attrition from in-transport abrasion and disintegration. This bed-material comminution strongly affects bed-material transport in the study area, reducing transport rates by 50%–90% along the length of the larger rivers in the study area. A comparison of the bed-material transport estimates with the morphologic analyses shows that alluvial gravel-bed channels have systematic and bounding relations between bed-material transport rate and attributes such as bar area and local transport capacity. By contrast, few such relations are evident for nonalluvial rivers with bedrock or mixed-bed substrates, which are apparently more influenced by local controls on channel geometry and sediment supply. At the scale of western Oregon, the physiographic and lithologic controls on the balance between bed-material supply and transport capacity exert far-reaching influence on the distribution of alluvial and nonalluvial channels and their consequently distinctive morphologies and behaviors

  2. Model of rough bed for numerical simulation of saltation

    Czech Academy of Sciences Publication Activity Database

    Kharlamova, Irina; Vlasák, Pavel

    2015-01-01

    Roč. 19, č. 3 (2015), s. 366-385 ISSN 1964-8189 R&D Projects: GA ČR GA103/09/1718; GA ČR GAP105/10/1574 Institutional support: RVO:67985874 Keywords : saltation * bed load transport * rough bed * armoured bed * bed roughness Subject RIV: BK - Fluid Dynamics Impact factor: 0.636, year: 2015

  3. Establishing Bedding Requirements during Transport and Monitoring Skin Temperature during Cold and Mild Seasons after Transport for Finishing Pigs

    Directory of Open Access Journals (Sweden)

    John McGlone

    2014-05-01

    Full Text Available The broad aim of this study was to determine whether bedding level in the transport trailer influenced pig performance and welfare. Specifically, the objective was to define the bedding requirements of pigs during transportation in commercial settings during cold and mild weather. Animals (n = 112,078 pigs on 572 trailers used were raised in commercial finishing sites and transported in trailers to commercial processing plants. Dead on arrival (DOA, non-ambulatory (NA, and total dead and down (D&D data were collected and skin surface temperatures of the pigs were measured by infrared thermography. Data were collected during winter (Experiment 1 and fall/spring (Experiment 2. Total D&D percent showed no interaction between bedding level and outside air temperature in any experiments. Average skin surface temperature during unloading increased with outside air temperature linearly in both experiments (P < 0.01. In conclusion, over-use of bedding may be economically inefficient. Pig skin surface temperature could be a useful measure of pig welfare during or after transport.

  4. Improvement of burnup analysis for pebble bed reactors with an accumulative fuel loading scheme

    International Nuclear Information System (INIS)

    Simanullang, Irwan Liapto; Obara, Toru

    2015-01-01

    Given the limitations of natural uranium resources, innovative nuclear power plant concepts that increase the efficiency of nuclear fuel utilization are needed. The Pebble Bed Reactor (PBR) shows some potential to achieve high efficiency in natural uranium utilization. To simplify the PBR concept, PBR with an accumulation fuel loading scheme was introduced and the Fuel Handling System (FHS) removed. In this concept, the pebble balls are added little by little into the reactor core until the pebble balls reach the top of the reactor core, and all pebble balls are discharged from the core at the end of the operation period. A code based on the MVP/MVP-BURN method has been developed to perform an analysis of a PBR with the accumulative fuel loading scheme. The optimum fuel composition was found using the code for high burnup performance. Previous efforts provided several motivations to improve the burnup performance: First, some errors in the input code were corrected. This correction, and an overall simplification of the input code, was implemented for easier analysis of a PBR with the accumulative fuel loading scheme. Second, the optimum fuel design had been obtained in the infinite geometry. To improve the optimum fuel composition, a parametric survey was obtained by varying the amount of Heavy Metal (HM) uranium per pebble and the degree of uranium enrichment. Moreover, an entire analysis of the parametric survey was obtained in the finite geometry. The results show that improvements in the fuel composition can lead to more accurate analysis with the code. (author)

  5. Load converter interactions with the secondary system in the Space Station Freedom power management and distribution DC test bed

    Science.gov (United States)

    Lebron, Ramon C.

    1992-01-01

    The NASA LeRC in Cleveland, Ohio, is responsible for the design, development, and assembly of the Space Station Freedom (SSF) Electrical Power System (EPS). In order to identify and understand system level issues during the SSF Program design and development phases, a system Power Management and Distribution (PMAD) DC test bed was assembled. Some of the objectives of this test bed facility are the evaluation of, system efficiency, power quality, system stability, and system protection and reconfiguration schemes. In order to provide a realistic operating scenario, dc Load Converter Units are used in the PMAD dc test bed to characterize the user interface with the power system. These units are dc to dc converters that provide the final system regulation before power is delivered to the load. This final regulation is required on the actual space station because the majority of user loads will require voltage levels different from the secondary bus voltage. This paper describes the testing of load converters in an end to end system environment (from solar array to loads) where their interactions and compatibility with other system components are considered. Some of the system effects of interest that are presented include load converters transient behavior interactions with protective current limiting switchgear, load converters ripple effects, and the effects of load converter constant power behavior with protective features such as foldback.

  6. Field Observation and Numerical Modeling of Bed-Material Transport Dynamics in the Lower Mississippi River

    Science.gov (United States)

    Ramirez, M. T.; Allison, M. A.; Meselhe, E. A.

    2012-12-01

    Understanding specific pathways for sand transport through the lower reaches of large rivers like the Mississippi is a key to addressing (1) significant source-to-sink geologic problems for sediment and particulate organic carbon and (2) environmental restoration efforts in deltas under threat from climate change. Five field studies were performed in the Mississippi River 75-100 km upstream of the Gulf of Mexico outlet in 2010 and 2011 at discharges ranging from 18,500 to 32,000 m3 s-1 to examine sand transport phenomena in the river channel. These studies utilized multibeam sonar bathymetric surveys, acoustic Doppler current profiler measurements of current velocity and acoustic backscatter, point-integrated isokinetic suspended sediment sampling, and channel-bed grab sampling to examine fluid flow and suspended/bedload sediment transport. Substantial interaction was observed between flow conditions in the river (boundary shear stress, turbulence intensity), channel-bed morphology (size and extent of sandy bedforms), and bed-material sand transport (quantity, transport mode, and spatial distribution). A lateral shift was observed in the region of maximum dune size and water column turbulence intensity from deep to shallow areas of lateral sand bars as water discharge increased, and is associated with the expansion of the bar top area experiencing critical shear stress conditions. Bed material was transported both in traction and in suspension at these water discharges, with the highest suspended mass flux rates associated with the part of the channel cross-section where the largest dunes were present, as a result of a relationship between bed shear stress, dune size, and turbulence intensity. We posit that the downriver flux of sand grains alternates between these two modes over relatively short spatial (up to a few km) and temporal scales. These results complicate the task of using cross-sectional flux measurements taken in lower reaches of large river channels

  7. Mass transport in bedded salt and salt interbeds

    International Nuclear Information System (INIS)

    Hwang, Y.; Pigford, T.H.; Chambre, P.L.; Lee, W.W.L.

    1989-08-01

    Salt is the proposed host rock for geologic repositories of nuclear waste in several nations because it is nearly dry and probably impermeable. Although experiments and experience at potential salt sites indicate that salt may contain brine, the low porosity, creep, and permeability of salt make it still a good choice for geologic isolation. In this paper we summarize several mass-transfer and transport analyses of salt repositories. The mathematical details are given in our technical reports

  8. Turbulence structure and sand transport over gravel and cobble beds in laboratory flumes

    Science.gov (United States)

    Characterizing the turbulence generated by flow over rough beds has become increasingly important in support of efforts to predict sediment transport downstream of dams. The advanced age and impending decommissioning of many dams have brought increased attention to the fate of sediments stored in r...

  9. Stoichiometric variation and loading capacity of a high-loading anammox attached film expanded bed (AAEEB) reactor.

    Science.gov (United States)

    Zhang, Yanlong; Ma, Haiyuan; Chen, Rong; Niu, Qigui; Li, Yu-You

    2018-04-01

    The nitrogen loading rate (NLR) of an anammox attached film expanded bed (AAFEB) reactor was increased from 5.0 to 60.0 gN/L/d. During the stable operational period, the TN removal efficiency maintained at 87.3 ± 2.5%, and a maximum nitrogen removal rate (NRR) of 44.9 ± 0.3 gN/L/d was achieved. Overload resulted in the sharp deterioration of reactor performance, the ratio of (Food/Microorganism)/SAA should be maintained at lower than 66 ± 7% to ensure the stable operation of the AAFEB reactor. New stoichiometric equations for the anammox process under the low NLR condition (5.0 gN/L/d) and the high NLR condition (50.0 gN/L/d) were proposed. The quantitative SAA-cytochrome heme C relationship was established for the first time that providing a simple way for monitoring the reactor performance. Substrate tolerance ability was significantly increased that proving the stability of the AAFEB reactor was continuously enhanced during the stable operational periods. Copyright © 2018 Elsevier Ltd. All rights reserved.

  10. Attrition of limestones by impact loading in fluidized beds: The influence of reaction conditions

    Energy Technology Data Exchange (ETDEWEB)

    Scala, Fabrizio [Istituto di Ricerche sulla Combustione, Consiglio Nazionale delle Ricerche, Napoli (Italy); Salatino, Piero [Istituto di Ricerche sulla Combustione, Consiglio Nazionale delle Ricerche, Napoli (Italy); Dipartimento di Ingegneria Chimica, Universita degli Studi di Napoli Federico II, Napoli (Italy)

    2010-09-15

    The extent of attrition associated with impact loading was studied for five different limestones pre-processed in fluidized bed under different reaction conditions. The experimental procedure was based on the measurement of the amount and the particle size distribution of the debris generated upon impact of sorbent samples against a target at velocities between 10 and 45 m/s. The effect of calcination, sulfation and calcination/re-carbonation on impact damage was assessed. Fragmentation by impact loading of the limestones was significant and increased with the impact velocity. Lime samples displayed the largest propensity to undergo impact damage, followed by sulfated, re-carbonated and raw limestones. Fragmentation of the sulfated samples followed a pattern typical of the failure of brittle materials. On the other hand, the behaviour of lime samples better conformed to a disintegration failure mode, with extensive generation of very fine fragments. Raw limestone and re-carbonated lime samples followed either of the two patterns depending on the sorbent nature. The extent of particle fragmentation increased after multiple impacts, but the incremental amount of fragments generated upon one impact decreased with the number of successive impacts. (author)

  11. Transport and storage of bed material in a gravel-bed channel during episodes of aggradation and degradation: a field and flume study

    Science.gov (United States)

    Bonnie Smith Pryor; Thomas Lisle; Diane Sutherland Montoya; Sue Hilton

    2011-01-01

    The dynamics of sediment transport capacity in gravel-bed rivers is critical to understanding the formation and preservation of fluvial landforms and formulating sediment-routing models in drainage systems. We examine transport-storage relations during cycles of aggradation and degradation by augmenting observations of three events of channel aggradation and...

  12. Understanding Sediment Sources, Pathways, and Sinks in Regional Sediment Management: Application of Wash Load and Bed-Material Load Concept

    National Research Council Canada - National Science Library

    Biedenham, David S; Hubbard, Lisa C; Thome, Colin R; Watson, Chester C

    2006-01-01

    ... through the fluvial system for sediments derived from various bed, bank, gully, and catchment sources thereby providing a reliable analytical foundation for effective regional sediment management...

  13. Improvement of loading and transport bodies of tunneling machines

    Science.gov (United States)

    Nosenko, A. S.; Isakov, V. S.; Domnitskiy, A. A.; Shemshura, E. A.; Zubov, V. V.

    2017-10-01

    The article discusses the use of sets of equipment for mining and construction of road tunnels with the use of a self-propelled vehicle and bunker loaders to transport the mined rock. A patented design of the tunneling combine loading body, which allows adjusting its performance and power consumption in the loading mode, is considered. Reducing stress in extreme situations will make it possible to avoid overloading the drive and increase the reliability of the combine as a whole. The scheme of one of the most promising variants of the wedge bunker loader with variable geometry of the conveying elements is presented. The proposed design solves the problem of “locking” the material in narrow parts of the conveying body or in places where loading and transport bodies of different width are connected, as well as in the blast-and-heap mode of the loader.

  14. Preliminary assessment of channel stability and bed-material transport in the Rogue River basin, southwestern Oregon

    Science.gov (United States)

    Jones, Krista L.; O'Connor, Jim E.; Keith, Mackenzie K.; Mangano, Joseph F.; Wallick, J. Rose

    2012-01-01

    Illinois River included in this study was treated as one reach. This stretch of the Illinois River is fully alluvial, with nearly continuous gravel bars flanking the channel. The width of the active channel is confined by the narrow topography of the valley. * The primary human activities that have likely influenced channel condition, bed-material transport, and the extent and area of bars are (1) historical gold mining throughout the basin, (2) historical and ongoing gravel mining from instream sites in the Tidal Reach and floodplain sites such as those in the Lower Applegate River Reach, (3) hydropower and flow control structures, (4) forest management and fires throughout the basin, and (5) dredging. These anthropogenic activities likely have varying effects on channel condition and the transport and deposition of sediment throughout the study area and over time. * Several vertical (aspect) aerial photographs (including the complete coverages of the study area taken in 1995, 2000, 2005, and 2009 and the partial coverages taken in 1967, 1968, 1969, and 1990) are available for assessing long-term changes in attributes such as channel condition, bar area, and vegetation cover. A Light Detection And Ranging (LiDAR) survey performed in 2007-2008 provides 1-m resolution topographic data for sections of the Grants Pass (RKM 178.5-167.6) and Lobster Creek (RKM 17.8-12 and 10-6.7) Reaches and the entire Tidal Reach. * Previous studies provide information for specific locations, including (1) an estimated average annual bed-material load of 76,000 m3 at the former Savage Rapids Dam site (RKM 173.1, Grants Pass Reach), (2) over 490 m of channel shifting from 1965 to 1991 in the Brushy Chutes area (RKM 142-141, Merlin Reach), (3) active sediment transport and channel processes in the Lobster Creek Reach, (4) lateral channel migration in the Tidal Reach, and (5) up to 1.8 m of bar aggradation from the town of Agness (RKM 45.1) to the Rogue River mouth following the flood in water

  15. Characterization of bed load discharge in unsteady flow events in an ephemeral channel

    Science.gov (United States)

    Halfi, Eran

    2017-04-01

    There are many methods and equations for estimating bedload flux in steady flow conditions. Yet, very little is known about the effect of very unsteady flows, such as flash floods, on bedload flux. The unpredictable nature of the floods together with many logistic difficulties and safety issues in monitoring explain this gap in knowledge. Global climate change may increase flood event occurrence, making their understanding even more crucial. This research focuses on two durations of flash floods where the flow is most rapidly changing: a) flash flood bore arriving on dry river bed and b) flash flood bore arriving on a column of moving water. The methodology of our study is based on the demonstrated ability of the Eshtemoa gauging station to automatically monitor the variation of bedload flux depending on flow and bed characteristics, along with innovative equipment including hydrophones and geophones for capturing acoustic signals of bedload sediments (1 Hz), video cameras for continuous monitoring of water surface velocity (by the LSPIV method to determine its structure and velocity) and 3-D velocimetry for characterizing turbulence (40 Hz). Additional to these, a well-planned deployment was carried out, including alerting sensors and cellular transmission, enabling to be onsite when bores arrive. During the winter of 2015-2016 two flow events were sufficiently large to transport significant amounts of bedload; the magnitude of the larger event occurs once in a few years. Calibration between the acoustic indirect sensor and the direct slot sampler allow determination of bedload flux at a frequency of 1 Hz. Analyses of the two events indicate an increase of the turbulent nature (increase of the turbulent kinetic energy and the instantaneous vertical velocities), shear stress and bedload flux during the rising limb in the first two minutes of bore arrival.

  16. Aeolian Sand Transport in the Planetary Context: Respective Roles of Aerodynamic and Bed-Dilatancy Thresholds

    Science.gov (United States)

    Marshall, J. R.; Borucki, J.; Bratton, C.

    1999-09-01

    The traditional view of aeolian sand transport generally estimates flux from the perspective of aerodynamic forces creating the airborne grain population, although it has been recognized that "reptation" causes a significant part of the total airborne flux; reptation involves both ballistic injection of grains into the air stream by the impact of saltating grains as well as the "nudging" of surface grains into a creeping motion. Whilst aerodynamic forces may initiate sand motion, it is proposed here that within a fully-matured grain cloud, flux is actually governed by two thresholds: an aerodynamic threshold, and a bed-dilatancy threshold. It is the latter which controls the reptation population, and its significance increases proportionally with transport energy. Because we only have experience with terrestrial sand transport, extrapolations of aeolian theory to Mars and Venus have adjusted only the aerodynamic factor, taking gravitational forces and atmospheric density as the prime variables in the aerodynamic equations, but neglecting reptation. The basis for our perspective on the importance of reptation and bed dilatancy is a set of experiments that were designed to simulate sand transport across the surface of a martian dune. Using a modified sporting crossbow in which a sand-impelling sabot replaced the bolt-firing mechanism, individual grains of sand were fired at loose sand targets with glancing angles typical of saltation impact; grains were projected at about 80 m/s to simulate velocities commensurate with those predicted for extreme martian aeolian conditions. The sabot impelling method permitted study of individual impacts without the masking effect of bed mobilization encountered in wind-tunnel studies. At these martian impact velocities, grains produced small craters formed by the ejection of several hundred grains from the bed. Unexpectedly, the craters were not elongated, despite glancing impact; the craters were very close to circular in planform

  17. Flow pattern analysis of a full-scale expanded granular sludge bed-type reactor under different organic loading rates.

    Science.gov (United States)

    Zheng, M X; Wang, K J; Zuo, J E; Yan, Z; Fang, H; Yu, J W

    2012-03-01

    The hydraulic characteristics of a lab-scale and a full-scale (275 m(3)) expanded granular sludge bed (EGSB)-type reactor under different organic loading rates varying from 10 kg COD m(-3)d(-1) to 45 kg COD m(-3)d(-1) were investigated. A modified combined model composed of two completely mixing regions and a plug flow region was sufficient for simulating the flow pattern of a full-scale EGSB-type reactor. Moreover, the outputs fitted the measured tracer distribution results well. The simplified model structure was in very good agreement with the physical structure of a full-scale EGSB-type reactor. The upflow (liquid+gas) velocity, high concentration of granular sludge, and gas hold-up effect may contribute to the generation of dead spaces (maximum of 19.5%). The bed expansion characteristics indicated that the sludge bed of the EGSB-type reactor performed as a suspended bed, in which the bed expansion was controlled between 20% and 30%, rather than the usually considered expanded bed. Copyright © 2011 Elsevier Ltd. All rights reserved.

  18. Cargo Loading and Unloading Efficiency Analysis in Multimodal Transport

    Directory of Open Access Journals (Sweden)

    Rafał Burdzik

    2014-08-01

    Full Text Available The paper presents assessment of the impact of the processes handling efficiency on the transport process based on research done in the real object, using same technologies and material handling equipment. The aim of the paper was to confirm importance of loading and unloading processes of palletized cargo as an initial and final link of multimodal transport by developing methods’ proposal for monitoring and assessing the effectiveness of cargo operations as well as development of measures and comparison estimators. The analysis of the manipulation operations’ duration throughout the transport process is based on the percentile rates of manipulation and carriage in total transport process duration and the percentage of manipulating time in the duration of the carriage. These indicators and examined loading and unloading times, are the basis for the development of scheduling algorithms for optimizing transport processes on the scale of the whole transport chain. This data is also a helpful input to support strategic decisions on the allocation of financial resources for the development of infrastructure and terminal equipment, warehouses and other facilities.

  19. A probabilistic definition of the bed load sediment flux: Theory (Invited)

    Science.gov (United States)

    Furbish, D. J.; Haff, P. K.; Roseberry, J. C.; Schmeeckle, M. W.

    2010-12-01

    We provide a concise, probabilistic definition of the bed load sediment flux. In treating particle positions and motions as stochastic quantities, a flux form of the Master Equation reveals that the volumetric flux involves an advective part equal to the product of an average particle velocity and the particle activity (the solid volume of particles in motion per unit streambed area), and a diffusive part involving the gradient of the product of the particle activity and a diffusivity that arises from the second moment of the probability density function of particle displacements. Gradients in the activity, instantaneous or time-averaged, therefore effect a particle flux, and time-averaged descriptions of the flux involve covariances of the particle activity, the particle velocity and the diffusivity, whose significance depends on the averaging timescale. The flux form of the Exner equation looks like a Fokker-Planck equation. The entrainment form of the Exner equation similarly involves advective and diffusive terms, but because it is based on the joint probability density function of particle hop distances and associated travel times, this form involves time derivative terms that represent a lag effect associated with the exchange of particles between the static and active states. The formulation highlights that the probability distribution of particle displacements figures prominently in describing particle motions across a range of scales, notably bearing on the possibility of anomalous versus Fickian diffusive behavior.

  20. Processes and parameters involved in modeling radionuclide transport from bedded salt repositories. Final report. Technical memorandum

    International Nuclear Information System (INIS)

    Evenson, D.E.; Prickett, T.A.; Showalter, P.A.

    1979-07-01

    The parameters necessary to model radionuclide transport in salt beds are identified and described. A proposed plan for disposal of the radioactive wastes generated by nuclear power plants is to store waste canisters in repository sites contained in stable salt formations approximately 600 meters below the ground surface. Among the principal radioactive wastes contained in these canisters will be radioactive isotopes of neptunium, americium, uranium, and plutonium along with many highly radioactive fission products. A concern with this form of waste disposal is the possibility of ground-water flow occurring in the salt beds and endangering water supplies and the public health. Specifically, the research investigated the processes involved in the movement of radioactive wastes from the repository site by groundwater flow. Since the radioactive waste canisters also generate heat, temperature is an important factor. Among the processes affecting movement of radioactive wastes from a repository site in a salt bed are thermal conduction, groundwater movement, ion exchange, radioactive decay, dissolution and precipitation of salt, dispersion and diffusion, adsorption, and thermomigration. In addition, structural changes in the salt beds as a result of temperature changes are important. Based upon the half-lives of the radioactive wastes, he period of concern is on the order of a million years. As a result, major geologic phenomena that could affect both the salt bed and groundwater flow in the salt beds was considered. These phenomena include items such as volcanism, faulting, erosion, glaciation, and the impact of meteorites. CDM reviewed all of the critical processes involved in regional groundwater movement of radioactive wastes and identified and described the parameters that must be included to mathematically model their behavior. In addition, CDM briefly reviewed available echniques to measure these parameters

  1. Drug loaded and ethylcellulose coated mesoporous silica for controlled drug release prepared using a pilot scale fluid bed system.

    Science.gov (United States)

    Hacene, Youcef Chakib; Singh, Abhishek; Van den Mooter, Guy

    2016-06-15

    The goal of this study was to test the feasibility to load non-ordered, non-spherical mesoporous silica with the model drug paracetamol, and subsequently coat the loaded particles using one single pilot scale fluid bed system equipped with a Wurster insert. Mesoporous silica particles (Davisil(®)) with a size ranging from 310 to 500μm and an average pore diameter of 15nm were loaded with paracetamol to 18.8% drug content. Subsequently, loaded cores were coated with ethylcellulose to obtain controlled drug release. Coating processing variables were varied following a full factorial design and their effect on drug release was assessed. Increasing coating solution feed rate and decreasing fluidizing air temperature were found to increase drug release rates. Increasing pore former level and decreasing coating level were found to increase drug release rates. The release medium's osmolality was varied using different sodium chloride concentrations, which was found to affect drug release rates. The results of this study clearly indicate the potential of non-ordered, non-spherical mesoporous silica as a reservoir carrier for the controlled release of drugs. Although non-spherical, we were able to reproducibly coat this carrier using a bottom spray fluid bed system. However, a major hurdle that needs to be tackled is the attrition the material suffers from during fluid bed processing. Copyright © 2016 Elsevier B.V. All rights reserved.

  2. Adsorption of phosphate from aqueous solutions and sewage using zirconium loaded okara (ZLO): Fixed-bed column study

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen, T.A.H. [Centre for Technology in Water and Wastewater, School of Civil and Environmental Engineering, University of Technology, Sydney (UTS), 15 Broadway, Ultimo, NSW 2007 (Australia); Ngo, H.H., E-mail: ngohuuhao121@gmail.com [Centre for Technology in Water and Wastewater, School of Civil and Environmental Engineering, University of Technology, Sydney (UTS), 15 Broadway, Ultimo, NSW 2007 (Australia); Guo, W.S. [Centre for Technology in Water and Wastewater, School of Civil and Environmental Engineering, University of Technology, Sydney (UTS), 15 Broadway, Ultimo, NSW 2007 (Australia); Pham, T.Q. [Faculty of Geography, University of Science, Vietnam National University, Hanoi (Viet Nam); Li, F.M. [College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100 (China); Nguyen, T.V. [Centre for Technology in Water and Wastewater, School of Civil and Environmental Engineering, University of Technology, Sydney (UTS), 15 Broadway, Ultimo, NSW 2007 (Australia); Bui, X.T. [Environmental Engineering and Management Research Group, Ton Duc Thang University, Ho Chi Minh City (Viet Nam); Faculty of Environment and Natural Resources, Ho Chi Minh City University of Technology-Vietnam National University, Ho Chi Minh City (Viet Nam)

    2015-08-01

    This study explores the potential of removing phosphorus from aqueous solutions and sewage by Zr(IV)-loaded okara (ZLO) in the fixed-bed column. Soybean residue (okara) was impregnated with 0.25 M Zr(IV) solution to prepare active binding sites for phosphate. The effect of several factors, including flow rate, bed height, initial phosphorus concentration, pH and adsorbent particle size on the performance of ZLO was examined. The maximum dynamic adsorption capacity of ZLO for phosphorus was estimated to be 16.43 mg/g. Breakthrough curve modeling indicated that Adams–Bohart model and Thomas model fitted the experimental data better than Yoon–Nelson model. After treatment with ZLO packed bed column, the effluent could meet the discharge standard for phosphorus in Australia. Successful desorption and regeneration were achieved with 0.2 NaOH and 0.1 HCl, respectively. The results prove that ZLO can be used as a promising phosphorus adsorbent in the dynamic adsorption system. - Highlights: • Dynamic adsorption of P from water and wastewater by Zr(IV)-loaded okara was tested. • Effects of column design parameters on the adsorption performance were investigated. • The dynamic adsorption capacity of Zr(IV)-loaded okara for P was reasonably high. • The spent column was effectively regenerated with 0.2 M NaOH followed by 0.1 M HCl. • Zr(IV)-loaded okara column was efficient in eliminating P from municipal sewage.

  3. Adsorption of phosphate from aqueous solutions and sewage using zirconium loaded okara (ZLO): Fixed-bed column study

    International Nuclear Information System (INIS)

    Nguyen, T.A.H.; Ngo, H.H.; Guo, W.S.; Pham, T.Q.; Li, F.M.; Nguyen, T.V.; Bui, X.T.

    2015-01-01

    This study explores the potential of removing phosphorus from aqueous solutions and sewage by Zr(IV)-loaded okara (ZLO) in the fixed-bed column. Soybean residue (okara) was impregnated with 0.25 M Zr(IV) solution to prepare active binding sites for phosphate. The effect of several factors, including flow rate, bed height, initial phosphorus concentration, pH and adsorbent particle size on the performance of ZLO was examined. The maximum dynamic adsorption capacity of ZLO for phosphorus was estimated to be 16.43 mg/g. Breakthrough curve modeling indicated that Adams–Bohart model and Thomas model fitted the experimental data better than Yoon–Nelson model. After treatment with ZLO packed bed column, the effluent could meet the discharge standard for phosphorus in Australia. Successful desorption and regeneration were achieved with 0.2 NaOH and 0.1 HCl, respectively. The results prove that ZLO can be used as a promising phosphorus adsorbent in the dynamic adsorption system. - Highlights: • Dynamic adsorption of P from water and wastewater by Zr(IV)-loaded okara was tested. • Effects of column design parameters on the adsorption performance were investigated. • The dynamic adsorption capacity of Zr(IV)-loaded okara for P was reasonably high. • The spent column was effectively regenerated with 0.2 M NaOH followed by 0.1 M HCl. • Zr(IV)-loaded okara column was efficient in eliminating P from municipal sewage

  4. Near-Bed Monitoring of Suspended Sediment during a Major Flood Event Highlights Deficiencies in Existing Event-Loading Estimates

    Directory of Open Access Journals (Sweden)

    Alistair Grinham

    2018-01-01

    Full Text Available Rates of fluvial sediment discharge are notoriously difficult to quantify, particularly during major flood events. Measurements are typically undertaken using event stations requiring large capital investment, and the high cost tends to reduce the spatial coverage of monitoring sites. This study aimed to characterise the near-bed suspended sediment dynamics during a major flood event using a low-cost approach. Monitoring nodes consisted of a total suspended sediment (TSS logger, a single stage sampler, and a time-lapse camera for a total cost of less than US$420. Seven nodes were deployed across an elevation gradient on the stream bank of Laidley Creek, Queensland, Australia, and two of these nodes successfully characterised the near-bed suspended sediment dynamics across a major flood event. Near-bed TSS concentrations were closely related to stream flow, with the contribution of suspended bed material dominating the total suspended load during peak flows. Observed TSS concentrations were orders of magnitude higher than historical monitoring data for this site collected using the State government event station. This difference was attributed to the event station pump inlet screening the suspended bed material prior to sample collection. The ‘first flush’ phenomenon was detected and attributed to a local resuspension of muddy crusts immediately upstream of the study site. This low-cost approach will provide an important addition to the existing monitoring of fluvial sediment discharge during flood events.

  5. Thrust load determination for the high pressure turbo unit of the pebble bed micro model / Jacobus Janse van Rensburg

    OpenAIRE

    Janse van Rensburg, Jacobus

    2006-01-01

    Commercial turbochargers used on earth-moving equipment, were used as the turbo machinery for the Pebble Bed Micro Model (PBMM) instead of custom-built turbo units. A premature thrust bearing failure occurred on the High Pressure Turbo Unit (HPTU) of the PBMM during a test. Due to the closed Brayton cycle operation of the PBMM, it might have been possible to exert larger thrust loads on the thrust bearing of the HPTU than normally present in the turbo diesel engine application. ...

  6. STUDI PEMODELAN DAN PERHITUNGAN TRANSPORT MONTE CARLO DALAM TERAS HTR PEBBLE BED

    Directory of Open Access Journals (Sweden)

    Zuhair .

    2013-01-01

    Full Text Available Konsep sistem energi VHTR baik yang berbahan bakar pebble (VHTR pebble bed maupun blok prismatik (VHTR prismatik menarik perhatian fisikawan reaktor nuklir. Salah satu kelebihan teknologi bahan bakar bola adalah menawarkan terobosan teknologi pengisian bahan bakar tanpa harus menghentikan produksi listrik. Selain itu, partikel bahan bakar pebble dengan kernel uranium oksida (UO2 atau uranium oksikarbida (UCO yang dibalut TRISO dan pelapisan silikon karbida (SiC dianggap sebagai opsi utama dengan pertimbangan performa tinggi pada burn-up bahan bakar dan temperatur tinggi. Makalah ini mendiskusikan pemodelan dan perhitungan transport Monte Carlo dalam teras HTR pebble bed. HTR pebble bed adalah reaktor berpendingin gas temperatur tinggi dan bermoderator grafit dengan kemampuan kogenerasi. Perhitungan dikerjakan dengan program MCNP5 pada temperatur 1200 K. Pustaka data nuklir energi kontinu ENDF/B-V dan ENDF/B-VI dimanfaatkan untuk melengkapi analisis. Hasil perhitungan secara keseluruhan menunjukkan konsistensi dengan nilai keff yang hampir sama untuk pustaka data nuklir yang digunakan. Pustaka ENDF/B-VI (66c selalu memproduksi keff lebih besar dibandingkan ENDF/B-V (50c maupun ENDF/B-VI (60c dengan bias kurang dari 0,25%. Kisi BCC memprediksi keff hampir selalu lebih kecil daripada kisi lainnya, khususnya FCC. Nilai keff kisi BCC lebih dekat dengan kisi FCC dengan bias kurang dari 0,19% sedangkan dengan kisi SH bias perhitungannya kurang dari 0,22%. Fraksi packing yang sedikit berbeda (BCC= 61%, SH= 60,459% tidak membuat bias perhitungan menjadi berbeda jauh. Estimasi keff ketiga model kisi menyimpulkan bahwa model BCC lebih bisa diadopsi dalam perhitungan HTR pebble bed dibandingkan model FCC dan SH. Verifikasi hasil estimasi ini perlu dilakukan dengan simulasi Monte Carlo atau bahkan program deterministik lainnya guna optimisasi perhitungan teras reaktor temperatur tinggi.   Kata-kunci: kernel, TRISO, bahan bakar pebble, HTR pebble bed

  7. Effects of three day bed-rest on circulatory, metabolic and hormonal responses to oral glucose load in endurance trained athletes and untrained subjects

    Science.gov (United States)

    Smorawinski, J.; Kubala, P.; Kaciuba-Uociako, H.; Nazar, K.; Titow-Stupnicka, E.; Greenleaf, J. E.

    1996-01-01

    Endurance trained long distance runners and untrained individuals underwent three days of bed rest and oral glucose loading. Before and after bed rest, individuals were given glucose tolerance tests, and their heart rates, blood pressure, blood glucose levels, insulin levels, and catecholamine interactions were measured. Results indicated that glucose tolerance is more affected by bed rest-induced deconditioning in untrained individuals than in trained individuals.

  8. Method of online cleanliness control for upward-facing transport mirrors in integration test bed

    International Nuclear Information System (INIS)

    Zhao Longbiao; Qin Lang; Zhou Guorui; Ye Yayun; Zhang Chuanchao; Miao Xinxiang; Wang Hongbin; Yuan Xiaodong; Wang Xiaohong; Cheng Xiaofeng

    2013-01-01

    An online cleanliness control method based on the online monitoring system was developed for controlling the particle pollution and damage of upward-facing transport mirrors in the integration test bed. By building up gas knife system, the online cleanliness processing was effectively achieved for the particle pollution on the mirror surface. By using the gas screen, the cleanliness of the mirror surface was effectively online maintained. The image processing system was applied to assessing the effect of online cleanliness processing. The experimental results indicate that the particle pollution was reduced by the gas knife and the gas screen was useful to avoid the settlement of particle pollution. (authors)

  9. Combining Inverse and Transport Modeling to Estimate Bacterial Loading and Transport in a Tidal Embayment

    Directory of Open Access Journals (Sweden)

    Mac Sisson

    2016-11-01

    Full Text Available Poquoson River is a tidal coastal embayment located along the Western Shore of the Chesapeake Bay about 4 km south of the York River mouth in the City of Poquoson and in York County, Virginia. Its drainage area has diversified land uses, including high densities of residence, agricultural, salt marsh land uses, as well as a National Wildlife Refuge. This embayment experiences elevated bacterial concentration due to excess bacterial inputs from storm water runoff, nonpoint sources, and wash off from marshes due to tide and wind-induced set-up and set-down. Bacteria can also grow in the marsh and small tributaries. It is difficult to use a traditional watershed model to simulate bacterial loading, especially in this low-lying marsh area with abundant wildlife, while runoff is not solely driven by precipitation. An inverse approach is introduced to estimate loading from unknown sources based on observations in the embayment. The estimated loadings were combined with loadings estimated from different sources (human, wildlife, agriculture, pets, etc. and input to the watershed model. The watershed model simulated long-term flow and bacterial loading and discharged to a three-dimensional transport model driven by tide, wind, and freshwater discharge. The transport model efficiently simulates the transport and fate of the bacterial concentration in the embayment and is capable of determining the loading reduction needed to improve the water quality condition of the embayment. Combining inverse, watershed, and transport models is a sound approach for simulating bacterial transport correctly in the coastal embayment with complex unknown bacterial sources, which are not solely driven by precipitation.

  10. Fission Product Transport and Source Terms in HTRs: Experience from AVR Pebble Bed Reactor

    Directory of Open Access Journals (Sweden)

    Rainer Moormann

    2008-01-01

    Full Text Available Fission products deposited in the coolant circuit outside of the active core play a dominant role in source term estimations for advanced small pebble bed HTRs, particularly in design basis accidents (DBA. The deposited fission products may be released in depressurization accidents because present pebble bed HTR concepts abstain from a gas tight containment. Contamination of the circuit also hinders maintenance work. Experiments, performed from 1972 to 88 on the AVR, an experimental pebble bed HTR, allow for a deeper insight into fission product transport behavior. The activity deposition per coolant pass was lower than expected and was influenced by fission product chemistry and by presence of carbonaceous dust. The latter lead also to inconsistencies between Cs plate out experiments in laboratory and in AVR. The deposition behavior of Ag was in line with present models. Dust as activity carrier is of safety relevance because of its mobility and of its sorption capability for fission products. All metal surfaces in pebble bed reactors were covered by a carbonaceous dust layer. Dust in AVR was produced by abrasion in amounts of about 5 kg/y. Additional dust sources in AVR were ours oil ingress and peeling of fuel element surfaces due to an air ingress. Dust has a size of about 1  m, consists mainly of graphite, is partly remobilized by flow perturbations, and deposits with time constants of 1 to 2 hours. In future reactors, an efficient filtering via a gas tight containment is required because accidents with fast depressurizations induce dust mobilization. Enhanced core temperatures in normal operation as in AVR and broken fuel pebbles have to be considered, as inflammable dust concentrations in the gas phase.

  11. Coupled dynamics of the co-evolution of gravel bed topography, flow turbulence and sediment transport in an experimental channel

    Science.gov (United States)

    Singh, Arvind; Foufoula-Georgiou, Efi; Porté-Agel, Fernando; Wilcock, Peter R.

    2012-12-01

    A series of flume experiments were conducted in a large experimental channel at the St. Anthony Falls Laboratory to understand the coupled dynamics of flow and bed forms above the sediment-water interface. Simultaneous high resolution measurements of velocity fluctuations, bed elevations and sediment flux at the downstream end of the channel, were made for a range of discharges. The probability density functions (pdfs) of bed elevation increments and instantaneous Reynolds stress reveal a power law tail behavior and a wavelet cross-correlation analysis depicts a strong dependence of these series across a range of scales, indicating a feedback between bed form dynamics and near-bed turbulence. These results complement our previous findings in which the signature of bed form evolution on the near-bed velocity fluctuations was confirmed via the presence of a spectral gap and two distinct power law scaling regimes in the spectral density of velocity fluctuations. We report herein a strong asymmetry in the probability distribution of bed elevation increments and instantaneous Reynolds stresses, the latter being further analyzed and interpreted via a quadrant analysis of velocity fluctuations in the longitudinal and vertical directions. We also report the presence of intermittency (multifractality) in bed elevation increments and interpret it, in view of the asymmetric nature of the pdfs, as the result of scale coupling. In other words, the geometric asymmetry at the bed form scale gets transferred down to a probabilistic asymmetry at all smaller scales indicating a local anisotropy in the energy transfer. Finally, we propose a predictive relationship between bed form averaged sediment transport rates and bed form averaged instantaneous Reynolds stress and validate it using our experimental data.

  12. Dynamic evaluation of a fixed bed anaerobic digestion process in response to organic overloads and toxicant shock loads.

    Science.gov (United States)

    Dupla, M; Conte, T; Bouvier, J C; Bernet, N; Steyer, J P

    2004-01-01

    This paper details a dynamic evaluation of a 1 m3 fixed bed anaerobic digestion reactor in response to organic overloads and toxicant shock loads. Raw industrial wine distillery wastewater was used as a reference substrate and several disturbances were applied to the process: (i) organic overloads with and without pH regulation in the feeding line, (ii) adding of ammonia in the input wastewater. The purpose of this study was to assess, using on-line instrumentation, the robustness of a fixed bed anaerobic digester. Anaerobic digestion processes have the reputation of being difficult to operate and prone to process instability due to external disturbances and the objective of this study was to demonstrate the possibility of such a reactor configuration for industrial use.

  13. Fluidized bed electrodes with high carbon loading for water desalination by capacitive deionization

    NARCIS (Netherlands)

    Doornbusch, G.J.; Dykstra, J.E.; Biesheuvel, P.M.; Suss, M.E.

    2016-01-01

    The use of carbon flow electrodes has significantly impacted electrochemical energy storage and capacitive deionization (CDI), but device performance is limited as these electrodes cannot surpass ∼20 wt% carbon while maintaining flowability. We here introduce flowable fluidized bed electrodes

  14. Dependence of saltation characteristics on bed organisation in numerical simulation

    Czech Academy of Sciences Publication Activity Database

    Kharlamova, Irina; Vlasák, Pavel

    2015-01-01

    Roč. 19, č. 1 (2015), s. 177-184 ISSN 1226-4806 R&D Projects: GA ČR GA103/09/1718; GA ČR GAP105/10/1574 Institutional support: RVO:67985874 Keywords : saltation parameters * bed roughness * bed structure * bed load transport * armoured bed Subject RIV: BK - Fluid Dynamics Impact factor: 0.922, year: 2015 http://link.springer.com/content/pdf/10.1007%2Fs12303-014-0029-3.pdf

  15. Contamination transfers during fuel transport cask loading. A concrete situation

    International Nuclear Information System (INIS)

    Fournel, B.; Turchet, J.P.; Faure, S.; Allinei, P.G.; Briquet, L.; Baubet, D.

    2002-01-01

    In 1998, a number of contamination cases detected during fuel shipments have been pointed out by the french nuclear safety authority. Wagon and casks external surfaces were partly contaminated upon arrival in Valognes railway terminal. Since then, measures taken by nuclear power plants operators in France and abroad solved the problem. In Germany, a report analyzing the situation in depth has been published in which correctives actions have been listed. In France, EDF launched a large cleanliness program (projet proprete radiologique) in order to better understand contamination transfers mechanisms during power plants exploitation and to list remediation actions to avoid further problems. In this context, CEA Department for Wastes Studies at Cadarache (CEA/DEN/DED) was in charge of a study about contamination transfers during fuel elements loading operations. It was decided to lead experiments for a concrete case. The loading of a transport cask at Tricastin-PWR-1 was followed in november 2000 and different analysis comprising water analysis and smear tests analysis were carried out and are detailed in this paper. Results are discussed and qualitatively compared to those obtained in Philippsburg-BWR, Germany for a similar set of tests. (authors)

  16. Determination of the solid consumption in the transport of sands in sea beds with gold 198

    International Nuclear Information System (INIS)

    Rodriguez A, G.

    1983-01-01

    The study of the movement of sediments in sea beds, is necessary when one plans to build a port. Among the techniques used for this studies, it is the radiotracer balance that gives an useful estimation of the quantity of sediment that it moves per day and by meter (perpendicular to the displacement). The main objectives of this work are: to) to present the characteristics of the obtaining of the used radiotracer, describing details those used safety measures, b) to describe the handling of the radiotracer and it radiological safety, during the transport and injection in the sea bottom, c) description of the detection way and the used equipment, d) to describe the information processing obtained in the field and finally, e) the estimate of the solid consumption and the determination of the direction and speed of displacement of those sediments in the sea bottom, in front of the Tabasco coast, to be used jointly with the information obtained by means of other techniques so that one can make a good planning of the operations of dredging during the construction and later on the maintenance of the Dos Bocas marine terminal. The first step is to obtain the radiotracer that in this case was sand of uniform grain metric, marked superficially with Gold-198. The second step is to transport the sand to the place of interest, to place it in the injection equipment and to deposit it in the sea bottom. The third step is to detect the radiotracer in the sea bed, from a craft that drags a sled, which takes mounted a scintillation detector of sodium iodide activated with thallium NaI(Tl) (probe). The fourth step is to process the field information and to obtain the corresponding results. (Author)

  17. Burnup performance of rock-like oxide (ROX) fuel in small pebble bed reactor with accumulative fuel loading scheme

    International Nuclear Information System (INIS)

    Simanullang, Irwan Liapto; Obara, Toru

    2017-01-01

    Highlights: • Burnup performance using ROX fuel in PBR with accumulative fuel loading scheme was analyzed. • Initial excess reactivity was suppressed by reducing 235 U enrichment in the startup condition. • Negative temperature coefficient was achieved in all condition of PBR with accumulative fuel loading scheme using ROX fuel. • Core lifetime of PBR with accumulative fuel loading scheme using ROX fuel was shorter than with UO 2 fuel. • In PBR with accumulative fuel loading scheme using ROX fuel, achieved discharged burnup can be as high as that for UO 2 fuel. - Abstract: The Japan Atomic Energy Agency (JAEA) has proposed rock-like oxide (ROX) fuel as a new, once-through type fuel concept. Here, burnup performance using ROX fuel was simulated in a pebble bed reactor with an accumulative fuel loading scheme. The MVP-BURN code was used to simulate the burnup calculation. Fuel of 5 g-HM/pebble with 20% 235 U enrichment was selected as the optimum composition. Discharged burnup could reach up to 218 GWd/t, with a core lifetime of about 8.4 years. However, high excess reactivity occurred in the initial condition. Initial fuel enrichment was therefore reduced from 20% to 4.65% to counter the initial excess reactivity. The operation period was reduced by the decrease of initial fuel enrichment, but the maximum discharged burnup was 198 GWd/t. Burnup performance of ROX fuel in this reactor concept was compared with that of UO 2 fuel obtained previously. Discharged burnup for ROX fuel in the PBR with an accumulative fuel loading scheme was as high as UO 2 fuel. Maximum power density could be lowered by introducing ROX fuel compared to UO 2 fuel. However, PBR core lifetime was shorter with ROX fuel than with UO 2 fuel. A negative temperature coefficient was achieved for both UO 2 and ROX fuels throughout the operation period.

  18. Preliminary assessment of channel stability and bed-material transport along Hunter Creek, southwestern Oregon

    Science.gov (United States)

    Jones, Krista L.; Wallick, J. Rose; O'Connor, Jim E.; Keith, Mackenzie K.; Mangano, Joseph F.; Risley, John C.

    2011-01-01

    This preliminary assessment of (1) bed-material transport in the Hunter Creek basin, (2) historical changes in channel condition, and (3) supplementary data needed to inform permitting decisions regarding instream gravel extraction revealed the following: Along the lower 12.4 km (kilometers) of Hunter Creek from its confluence with the Little South Fork Hunter Creek to its mouth, the river has confined and unconfined segments and is predominately alluvial in its lowermost 11 km. This 12.4-km stretch of river can be divided into two geomorphically distinct study reaches based primarily on valley physiography. In the Upper Study Reach (river kilometer [RKM] 12.4-6), the active channel comprises a mixed bed of bedrock, boulders, and smaller grains. The stream is confined in the upper 1.4 km of the reach by a bedrock canyon and in the lower 2.4 km by its valley. In the Lower Study Reach (RKM 6-0), where the area of gravel bars historically was largest, the stream flows over bed material that is predominately alluvial sediments. The channel alternates between confined and unconfined segments. The primary human activities that likely have affected bed-material transport and the extent and area of gravel bars are (1) historical and ongoing aggregate extraction from gravel bars in the study area and (2) timber harvest and associated road construction throughout the basin. These anthropogenic activities likely have varying effects on sediment transport and deposition throughout the study area and over time. Although assessing the relative effects of these anthropogenic activities on sediment dynamics would be challenging, the Hunter Creek basin may serve as a case study for such an assessment because it is mostly free of other alterations to hydrologic and geomorphic processes such as flow regulation, dredging, and other navigation improvements that are common in many Oregon coastal basins. Several datasets are available that may support a more detailed physical assessment

  19. Gas composition of sludge residue profiles in a sludge treatment reed bed between loadings

    DEFF Research Database (Denmark)

    Larsen, Julie Dam; Nielsen, Steen M; Scheutz, Charlotte

    2017-01-01

    Treatment of sludge in sludge treatment reed bed systems includes dewatering and mineralization. The mineralization process, which is driven by microorganisms, produces different gas species as by-products. The pore space composition of the gas species provides useful information on the biological...... processes occurring in the sludge residue. In this study, we measured the change in composition of gas species in the pore space at different depth levels in vertical sludge residue profiles during a resting period of 32 days. The gas composition of the pore space in the sludge residue changed during...... the resting period. As the resting period proceeded, atmospheric air re-entered the pore space at all depth levels. The methane (CH4) concentration was at its highest during the first part of the resting period, and then declined as the sludge residue became more dewatered and thereby aerated. In the pore...

  20. Steady-state and dynamic evaluation of the electric propulsion system test bed vehicle on a road load simulator

    Science.gov (United States)

    Dustin, M. O.

    1983-01-01

    The propulsion system of the Lewis Research Center's electric propulsion system test bed vehicle was tested on the road load simulator under the DOE Electric and Hybrid Vehicle Program. This propulsion system, consisting of a series-wound dc motor controlled by an infinitely variable SCR chopper and an 84-V battery pack, is typical of those used in electric vehicles made in 1976. Steady-state tests were conducted over a wide range of differential output torques and vehicle speeds. Efficiencies of all of the components were determined. Effects of temperature and voltage variations on the motor and the effect of voltage changes on the controller were examined. Energy consumption and energy efficiency for the system were determined over the B and C driving schedules of the SAE J227a test procedure.

  1. Slow-wave sleep estimation on a load-cell-installed bed: a non-constrained method

    International Nuclear Information System (INIS)

    Choi, Byung Hun; Chung, Gih Sung; Lee, Jin-Seong; Jeong, Do-Un; Park, Kwang Suk

    2009-01-01

    Polysomnography (PSG) involves simultaneous and continuous monitoring of relevant normal and abnormal physiological activity during sleep. At present, an electroencephalography-based rule is generally used for classifying sleep stages. However, scoring the PSG record is quite laborious and time consuming. In this paper, movement and cardiac activity were measured unobtrusively by a load-cell-installed bed, and sleep was classified into two stages: slow-wave sleep and non-slow-wave sleep. From the measured cardiac activity, we extracted heartbeat data and calculated heart rate variability parameters: standard deviation of R–R intervals SDNN, low frequency-to-high frequency ratio, alpha of detrended fluctuation analysis and correlation coefficient of R–R interval. The developed system showed a substantial concordance with PSG results when compared using a contingency test. The mean epoch-by-epoch agreement between the proposed method and PSG was 92.5% and Cohen's kappa was 0.62

  2. Effect of Mass-Transport Limitations on the Performance of a Packed Bed Membrane Reactor for Partial Oxidations. Transport from the Membrane to the Packed Bed

    NARCIS (Netherlands)

    van Sint Annaland, M.; Kurten, U.; Kuipers, J.A.M.

    2007-01-01

    With a packed bed membrane reactor, the product yield can be significantly enhanced for partial oxidation systems, via distributive addition of oxygen to the reaction mixture along the axial coordinate of the reactor, provided that the reaction order in oxygen of the formation rate of the target

  3. Multimodal transport and TransLoad facilities in Arkansas.

    Science.gov (United States)

    2015-01-01

    National Priorities consist of building a clean and ecient 21st century : transportation sector, and Multimodal Transportation is one of ve : Transportation System Eciency strategies at the US Department of Energy. Six : locomotives co...

  4. Microforms in gravel bed rivers: Formation, disintegration, and effects on bedload transport

    Science.gov (United States)

    Strom, K.; Papanicolaou, A.N.; Evangelopoulos, N.; Odeh, M.

    2004-01-01

    This research aims to advance current knowledge on cluster formation and evolution by tackling some of the aspects associated with cluster microtopography and the effects of clusters on bedload transport. The specific objectives of the study are (1) to identify the bed shear stress range in which clusters form and disintegrate, (2) to quantitatively describe the spacing characteristics and orientation of clusters with respect to flow characteristics, (3) to quantify the effects clusters have on the mean bedload rate, and (4) to assess the effects of clusters on the pulsating nature of bedload. In order to meet the objectives of this study, two main experimental scenarios, namely, Test Series A and B (20 experiments overall) are considered in a laboratory flume under well-controlled conditions. Series A tests are performed to address objectives (1) and (2) while Series B is designed to meet objectives (3) and (4). Results show that cluster microforms develop in uniform sediment at 1.25 to 2 times the Shields parameter of an individual particle and start disintegrating at about 2.25 times the Shields parameter. It is found that during an unsteady flow event, effects of clusters on bedload transport rate can be classified in three different phases: a sink phase where clusters absorb incoming sediment, a neutral phase where clusters do not affect bedload, and a source phase where clusters release particles. Clusters also increase the magnitude of the fluctuations in bedload transport rate, showing that clusters amplify the unsteady nature of bedload transport. A fourth-order autoregressive, autoregressive integrated moving average model is employed to describe the time series of bedload and provide a predictive formula for predicting bedload at different periods. Finally, a change-point analysis enhanced with a binary segmentation procedure is performed to identify the abrupt changes in the bedload statistic characteristics due to the effects of clusters and detect the

  5. The influence of transport phenomena on the fluidized bed combustion of a single carbon particle

    NARCIS (Netherlands)

    Prins, W.; van Swaaij, Willibrordus Petrus Maria

    1990-01-01

    The burning rate and temperature of the carbon particles are known to affect the efficiency of a fluidized bed combustor, and also the emission levels of undesired noxious components. The main results of an extensive study on the fluidized bed combustion behaviour of a single carbon particle [1] are

  6. Mathematical Determination of Thermal Load for Fluidised Bed Furnaces Using Sawdust

    Directory of Open Access Journals (Sweden)

    Antonescu Nicolae

    2014-06-01

    Full Text Available For technical applications, a physical model capable of predicting the particle evolution in the burning process along its trajectory through the furnace is very useful. There are two major demands: all the thermo-dynamic processes that describe the particle burning process must be accounted and the model must be written in such equation terms to allow the intervention for parameter settings and particle definition. The computations were performed for the following parameters: furnace average temperature between 700 and 1200 °C, size of the sawdust particle from 4 to 6 mm and fix carbon ignition between 500 and 900 °C. The values obtained for the characteristic parameters of the burning process ranged from 30 to 60 [kg/(h·m3] for the gravimetrical burning speed WGh and from 150 to 280 [kW/m3] for the volumetric thermal load of the furnace QV. The main conclusion was that the calculus results are in good agreement with the experimental data from the pilot installations and the real-case measurements in the sawdust working boiler furnaces or pre-burning chambers. Another very important conclusion is that the process speed variation, when the furnace temperature changes, confirms the thermo-kinetic predictions, namely that the burning process speed decreases when the furnace temperature increases.

  7. Liquid transportation fuels via large-scale fluidised-bed gasification of lignocellulosic biomass

    Energy Technology Data Exchange (ETDEWEB)

    Hannula, I.; Kurkela, E.

    2013-04-15

    With the objective of gaining a better understanding of the system design trade-offs and economics that pertain to biomass-to-liquids processes, 20 individual BTL plant designs were evaluated based on their technical and economic performance. The investigation was focused on gasification-based processes that enable the conversion of biomass to methanol, dimethyl ether, Fischer-Tropsch liquids or synthetic gasoline at a large (300 MWth of biomass) scale. The biomass conversion technology was based on pressurised steam/O2-blown fluidised-bed gasification, followed by hot-gas filtration and catalytic conversion of hydrocarbons and tars. This technology has seen extensive development and demonstration activities in Finland during the recent years and newly generated experimental data has also been used in our simulation models. Our study included conceptual design issues, process descriptions, mass and energy balances and production cost estimates. Several studies exist that discuss the overall efficiency and economics of biomass conversion to transportation liquids, but very few studies have presented a detailed comparison between various syntheses using consistent process designs and uniform cost database. In addition, no studies exist that examine and compare BTL plant designs using the same front-end configuration as described in this work. Our analysis shows that it is possible to produce sustainable low-carbon fuels from lignocellulosic biomass with first-law efficiency in the range of 49.6-66.7% depending on the end-product and process conditions. Production cost estimates were calculated assuming Nth plant economics and without public investment support, CO2 credits or tax assumptions. They are 58-65 euro/MWh for methanol, 58-66 euro/MWh for DME, 64-75 euro/MWh for Fischer-Tropsch liquids and 68-78 euro/MWh for synthetic gasoline. (orig.)

  8. Boulder-Faced Log Dams and other Alternatives for Gabion Check Dams in First-Order Ephemeral Streams with Coarse Bed Load in Ethiopia

    Science.gov (United States)

    Nyssen, Jan; Gebreslassie, Seifu; Assefa, Romha; Deckers, Jozef; Guyassa, Etefa; Poesen, Jean; Frankl, Amaury

    2017-04-01

    Many thousands of gabion check dams have been installed to control gully erosion in Ethiopia, but several challenges still remain, such as the issue of gabion failure in ephemeral streams with coarse bed load, that abrades at the chute step. As an alternative for gabion check dams in torrents with coarse bed load, boulder-faced log dams were conceived, installed transversally across torrents and tested (n = 30). For this, logs (22-35 cm across) were embedded in the banks of torrents, 0.5-1 m above the bed and their upstream sides were faced with boulders (0.3-0.7 m across). Similar to gabion check dams, boulder-faced log dams lead to temporary ponding, spreading of peak flow over the entire channel width and sediment deposition. Results of testing under extreme flow conditions (including two storms with return periods of 5.6 and 7 years) show that 18 dams resisted strong floods. Beyond certain flood thresholds, represented by proxies such as Strahler's stream order, catchment area, D95 or channel width), 11 log dams were completely destroyed. Smallholder farmers see much potential in this type of structure to control first-order torrents with coarse bed load, since the technique is cost-effective and can be easily installed.

  9. Preliminary assessment of channel stability and bed-material transport in the Tillamook Bay tributaries and Nehalem River basin, northwestern Oregon

    Science.gov (United States)

    Jones, Krista L.; Keith, Mackenzie K.; O'Connor, Jim E.; Mangano, Joseph F.; Wallick, J. Rose

    2012-01-01

    relation between transport capacity and sediment is more ambiguous for the fluvial reaches on the Wilson and Miami Rivers, but transport-limited conditions are likely for at least parts of these reaches. Some of these reaches have possibly evolved from sediment supply-limited to transport-limited over the last several decades in response to changing basin and climate conditions. * Because of exceedingly low gradients, all the tidal reaches are transport-limited. Bed material in these reaches, however, is primarily sand and finer grain-size material and probably transported as suspended load from upstream reaches. These reaches will be most susceptible to watershed conditions affecting the supply and transport of fine sediment. * Compared to basins on the southwestern Oregon coast, such as the Chetco and Rogue River basins, these six basins likely transport overall less gravel bed material. Although tentative in the absence of actual transport measurements, this conclusion is supported by the much lower area and frequency of bars and longer tidal reaches along all the northcoast rivers examined in this study. * Previous studies suggest that the expansive and largely unvegetated bars visible in the 1939 photographs are primarily associated with voluminous sedimentation starting soon after the first Tillamook Burn fire in 1933. However, USGS studies of temporal bar trends in other Oregon coastal rivers unaffected by the Tillamook Burn show similar declines in bar area over approximately the same analysis period. In the Umpqua and Chetco River basins, historical declines in bar area are associated with long-term decreases in flood magnitude. Other factors may include changes in the type and volume of large wood and riparian vegetation. Further characterization of hydrology patterns in these basins and possible linkages with climate factors related to flood peaks, such as the Pacific Decadal Oscillation, could support inferences of expected future changes in vegetation

  10. Flow fields, bed shear stresses, and suspended bed sediment dynamics in bifurcations of a large river

    Science.gov (United States)

    Szupiany, R. N.; Amsler, M. L.; Hernandez, J.; Parsons, D. R.; Best, J. L.; Fornari, E.; Trento, A.

    2012-11-01

    Channel bifurcations associated with bars and islands are important nodes in braided rivers and may control flow partitioning and thus affect downstream confluences, as well as the formation and dynamics of bars. However, the morphodynamic processes associated with bar formation are poorly understood, and previous studies have largely concerned laboratory experiments, small natural streams, or numerical analyses with large Froude numbers, high slopes, and low Shields stresses. In these cases, the morphologic changes at bifurcations are relatively rapid, with predominant bed load transport and the suspended load playing a minor role. In this paper, the evolution of the flow structure and suspended bed sediment transport along four expansion-diffluence units in the Rio Paraná, Argentina, are described. The Rio Paraná is a large multichannel river with a bed composed of medium and fine sands and possesses low Froude numbers and high suspended bed material transport. Primary and secondary flow velocity components were measured with an acoustic Doppler current profiler (ADCP) along the expansion-diffluence units, and the backscatter signal of the ADCP was calibrated to allow simultaneous measurements of suspended bed sediment concentrations. The interactions between these variables show that the cores of primary flow velocity and suspended bed sediment concentration do not necessarily follow the thalweg at the bifurcation and that inertial effects on the suspended bed sediment may influence the morphodynamics of bar formation. It is suggested that changes in flow stage, as well as the presence of vegetation, may further increase the deposition of suspended bed sediment at the bar head. This study suggests that the ratio of suspended bed material to bed load is an important factor controlling the morphodynamics of bifurcations in large sand bed braided rivers.

  11. Testing the feasibility of using a conveyor belt to load weanling and nursery pigs for transportation

    Science.gov (United States)

    Transportation is known to be a multi-faceted stressor, with the process of loading being one of the most significant factors impacting the stress to which animals are exposed. This project was designed to determine if using a conveyor to load pigs into the top deck of a simulated straight deck trai...

  12. Maximal load of the vitamin B12 transport system

    DEFF Research Database (Denmark)

    Lildballe, Dorte L; Mutti, Elena; Birn, Henrik

    2012-01-01

    Several studies suggest that the vitamin B12 (B12) transport system can be used for the cellular delivery of B12-conjugated drugs, also in long-term treatment Whether this strategy will affect the endogenous metabolism of B12 is not known. To study the effect of treatment with excess B12...... levels for methylenetetrahydrofolate reductase in kidneys and for transcobalamin and transcobalamin receptor in the salivary glands were reduced. Our study confirms the feasibility of delivering drugs through the B12 transport system but emphasises that B12 status should be monitored because...... there is a risk of decreasing the transport of endogenous B12. This risk may lead to B12 deficiency during prolonged treatment....

  13. Bed Degradation and Sediment Export from the Missouri River after Dam Construction and River Training: Significance to Lower Mississippi River Sediment Loads

    Science.gov (United States)

    Blum, M. D.; Viparelli, E.; Sulaiman, Z. A.; Pettit, B. S.

    2016-12-01

    More than 40,000 dams have been constructed in the Mississippi River drainage basin, which has had a dramatic impact on suspended sediment load for the Mississippi delta. The most significant dams were constructed in the 1950s on the Missouri River in South Dakota, after which total suspended loads for the lower Mississippi River, some 2500 km downstream, were cut in half: gauging station data from the Missouri-Mississippi system show significant load reductions immediately after dam closure, followed by a continued downward trend since that time. The delta region is experiencing tremendous land loss in response to acceleration of global sea-level rise, and load reductions of this magnitude may place severe limits on mitigation efforts. Here we examine sediment export from the Missouri system due to bed scour. The US Army Corps of Engineers has compiled changes in river stage at constant discharge for 8 stations between the lowermost dam at Yankton, South Dakota and the Missouri-Mississippi confluence at St. Louis (a distance of 1250 river km), for the period 1930-2010, which we have updated to 2015. These data show two general reaches of significant bed degradation. The first extends from the last major dam at Yankton, South Dakota downstream 300 km to Omaha, Nebraska, where degradation in response to the dam exceeds 3 m. The second reach, with >2.5 m of degradation, occurs in and around Kansas City, Missouri, and has been attributed to river training activities. The reach between Omaha and Kansas City, as well as the lower Missouri below Kansas City, show River due to bed scour following dam construction and river training. This number equates to 20-25 million tons per year, which is sufficient to account for 30% of the total Missouri River load, and 15% of the total post-dam annual sediment load for the lower Mississippi River. For perspective, the quantity of sediment exported from the Missouri River due to bed scour is greater than the total load for all

  14. Sediment Transport on Continental Shelves: Storm Bed Formation and Preservation in Heterogeneous Sediments

    Science.gov (United States)

    2012-01-01

    extends from fair-weather wave base to the beach berm or coastal dune . Observations and modelling studies show that some sand is removed from the...deposit. The top is wave rippled and overlain by fine sediment. (B) Example of hummocky cross stratification (HCS) from the Ferron Sand - stone in Utah...xDept. of Earth Science, Memorial University of Newfoundland, St. Johns, Newfoundland, Canada ABSTRACT Many storm beds are constructed of silt/ sand

  15. Dynamic model development and validation for a nitrifying moving bed biofilter: Effect of temperature and influent load on the performance

    DEFF Research Database (Denmark)

    Sin, Gürkan; Weijma, Jan; Spanjers, Henri

    2008-01-01

    A mathematical model with adequate complexity integrating hydraulics, biofilm and microbial conversion processes is successfully developed for a continuously moving bed biofilter performing tertiary nitrification. The model was calibrated and validated using data from Nether Stowey pilot plant...

  16. Two-phase model of hydrogen transport to optimize nanoparticle catalyst loading for hydrogen evolution reaction

    DEFF Research Database (Denmark)

    Kemppainen, Erno; Halme, Janne; Hansen, Ole

    2016-01-01

    With electrocatalysts it is important to be able to distinguish between the effects of mass transport and reaction kinetics on the performance of the catalyst. When the hydrogen evolution reaction (HER) is considered, an additional and often neglected detail of mass transport in liquid...... is the evolution and transport of gaseous H2, since HER leads to the continuous formation of H2 bubbles near the electrode. We present a numerical model that includes the transport of both gaseous and dissolved H2, as well as mass exchange between them, and combine it with a kinetic model of HER at platinum (Pt......) nanoparticle electrodes. We study the effect of the diffusion layer thickness and H2 dissolution rate constant on the importance of gaseous transport, and the effect of equilibrium hydrogen coverage and Pt loading on the kinetic and mass transport overpotentials. Gaseous transport becomes significant when...

  17. 49 CFR 174.84 - Position in train of loaded placarded rail cars, transport vehicles, freight containers or bulk...

    Science.gov (United States)

    2010-10-01

    ... CARRIAGE BY RAIL Handling of Placarded Rail Cars, Transport Vehicles and Freight Containers § 174.84 Position in train of loaded placarded rail cars, transport vehicles, freight containers or bulk packagings... 49 Transportation 2 2010-10-01 2010-10-01 false Position in train of loaded placarded rail cars...

  18. Robust transport by multiple motors with nonlinear force–velocity relations and stochastic load sharing

    International Nuclear Information System (INIS)

    Kunwar, Ambarish; Mogilner, Alexander

    2010-01-01

    Transport by processive molecular motors plays an important role in many cell biological phenomena. In many cases, motors work together to transport cargos in the cell, so it is important to understand the mechanics of the multiple motors. Based on earlier modeling efforts, here we study effects of nonlinear force–velocity relations and stochastic load sharing on multiple motor transport. We find that when two or three motors transport the cargo, then the nonlinear and stochastic effects compensate so that the mechanical properties of the transport are robust. Similarly, the transport is insensitive to compliance of the cargo-motor links. Furthermore, the rate of movement against moderate loads is not improved by increasing the small number of motors. When the motor number is greater than 4, correlations between the motors become negligible, and the earlier analytical mean-field theory of the multiple motor transport holds. We predict that the effective diffusion of the cargo driven by the multiple motors under load increases by an order of magnitude compared to that for the single motor. Finally, our simulations predict that the stochastic effects are responsible for a significant dispersion of velocities generated by the 'tug-of-war' of the multiple opposing motors

  19. Estimation of transported pollutant load in Ardila catchment using the SWAT model

    OpenAIRE

    DURÃO, A.; LEITÃO, P.; BRITO, D.; FERNANDES, R.M.; NEVES, R.; MORAIS, M.

    2011-01-01

    Excess of organic matter and nutrients in the water body promotes algae blooms, which can accelerate the eutrophication process, situation often observed in the Ardila river. This river was identified as very polluted and classified as critical for Alqueva-Pedrogão System. The aim of this study was to estimate the transported nutrients load in a transboundary catchment using the SWAT (Soil and Water Assessment Tool) model and to determine the contribution off nutrients load in the entire catc...

  20. Flow regulation in the Swiss Alps: a river network modelling approach to investigate the impacts on bed load and grain size distribution

    Science.gov (United States)

    Costa, A.; Molnar, P.; Schmitt, R. J. P.

    2017-12-01

    The grain size distribution (GSD) of river bed sediment results from the long term balance between transport capacity and sediment supply. Changes in climate and human activities may alter the spatial distribution of transport capacity and sediment supply along channels and hence impact local bedload transport and GSD. The effects of changed flow are not easily inferable due the non-linear, threshold-based nature of the relation between discharge and sediment mobilization, and the network-scale control on local sediment supply. We present a network-scale model for fractional sediment transport to quantify the impact of hydropower (HP) operations on river network GSD. We represent the river network as a series of connected links for which we extract the geometric characteristics from satellite images and a digital elevation model. We assign surface roughness based on the channel bed GSD. Bed shear stress is estimated at link-scale under the assumptions of rectangular prismatic cross sections and normal flow. The mass balance between sediment supply and transport capacity, computed with the Wilcock and Crowe model, determines transport rates of multiple grain size classes and the resulting GSD. We apply the model to the upper Rhone basin, a large Alpine basin in Switzerland. Since 1960s, changed flow conditions due to HP operations and sediment storage behind dams have potentially altered the sediment transport of the basin. However, little is known on the magnitude and spatial distribution of these changes. We force the model with time series of daily discharge derived with a spatially distributed hydrological model for pre and post HP scenarios. We initialize GSD under the assumption that coarse grains (d90) are mobilized only during mean annual maximum flows, and on the basis of ratios between d90 and characteristic diameters estimated from field measurements. Results show that effects of flow regulation vary significantly in space and in time and are grain size

  1. Effect of hydraulic parameters on sediment transport capacity in overland flow over erodible beds

    NARCIS (Netherlands)

    Ali, M.; Sterk, G.; Seeger, K.M.; Boersema, M.P.; Peters, P.D.

    2012-01-01

    Sediment transport is an important component of the soil erosion process, which depends on several hydraulic parameters like unit discharge, mean flow velocity, and slope gradient. In most of the previous studies, the impact of these hydraulic parameters on transport capacity was studied for

  2. Modeling Non-Fickian Transport and Hyperexponential Deposition for Deep Bed Filtration

    DEFF Research Database (Denmark)

    Yuan, Hao; Shapiro, Alexander

    2010-01-01

    coefficients. For such cases the elliptic equation excels the advection dispersion equation in both fitting breakthrough curves and predicting deposition profiles related to natural or highly heterogeneous porous media. The deposition hyperexponentiality can be caused by the following three mechanisms...... influencing breakthrough curves and deposition profiles for the deep bed filtration systems. Results are compared with a large set of experimental observations. Our findings show that highly dispersed breakthrough curves, e.g. those with early arrivals and large ending tails, correspond to large dispersion...

  3. Bed morphology, flow structure, and sediment transport at the outlet of Lake Huron and in the upper St. Clair River

    Science.gov (United States)

    Czuba, J.A.; Best, J.L.; Oberg, K.A.; Parsons, D.R.; Jackson, P.R.; Garcia, M.H.; Ashmore, P.

    2011-01-01

    An integrated multibeam echo sounder and acoustic Doppler current profiler field survey was conducted in July 2008 to investigate the morphodynamics of the St. Clair River at the outlet of Lake Huron. The principal morphological features of the upper St. Clair River included flow-transverse bedforms that appear weakly mobile, erosive bedforms in cohesive muds, thin non-cohesive veneers of weakly mobile sediment that cover an underlying cohesive (till or glacio-lacustrine) surface, and vegetation that covers the bed. The flow was characterized by acceleration as the banks constrict from Lake Huron into the St. Clair River, an approximately 1500-m long region of flow separation downstream from the Blue Water Bridge, and secondary flow connected to: i) channel curvature; ii) forcing of the flow by local bed topography, and iii) flow wakes in the lee side of ship wrecks. Nearshore, sand-sized, sediment from Lake Huron was capable of being transported into, and principally along, the banks of the upper St. Clair River by the measured flow. A comparison of bathymetric surveys conducted in 2007 and 2008 identifies that the gravel bed does undergo slow downstream movement, but that this movement does not appear to be generated by the mean flow, and could possibly be caused by ship-propeller-induced turbulence. The study results suggest that the measured mean flow and dredging within the channel have not produced major scour of the upper St. Clair River and that the recent fall in the level of Lake Huron is unlikely to have been caused by these mechanisms. ?? 2011.

  4. Modelling dynamic transport and adsorption of arsenic in soil-bed filters for long-term performance evaluation

    Science.gov (United States)

    Mondal, Sourav; Mondal, Raka; de, Sirshendu; Griffiths, Ian

    2017-11-01

    Purification of contaminated water following the safe water guidelines while generating sufficiently large throughput is a crucial requirement for the steady supply of safe water to large populations. Adsorption-based filtration processes using a multilayer soil bed has been posed as a viable method to achieve this goal. This work describes the theory of operation and prediction of the long-term behaviour of such a system. The fixed-bed column has a single input of contaminated water from the top and an output from the bottom. As the contaminant passes through the column, it is adsorbed by the medium. Like any other adsorption medium, the filter has a certain lifespan, beyond which the filtrate does not meet the safe limit of drinking water, which is defined as `breakthrough'. A mathematical model is developed that couples the fluid flow through the porous medium to the convective, diffusive and adsorptive transport of the contaminant. The results are validated with experimental observations and the model is then used to predict the breakthrough and lifetime of the filter. The key advantage of this model is that it can predict the long-term behaviour of any adsorption column system for any set of physical characteristics of the system. This worked was supported by the EPSRC Global Challenge Research Fund Institutional Sponsorship 2016.

  5. Airborne pollutants. Transports, effects and critical loads; Lufttransporterte forurensninger. Tilfoersler, virkninger og taalegrenser

    Energy Technology Data Exchange (ETDEWEB)

    Floeysand, I.; Loebersli, E. [eds.

    1996-01-01

    The report from a conference concerns two Norwegian research programmes. The first one deals with the transports and effects of airborne pollutants, and the second one relates to the critical loads of nature. A number of 17 papers from the conference are prepared. 318 refs., 57 figs., 22 tabs.

  6. Transport of phosphorus, wash load and suspended sediment in the River Varde A in southwest Jutland, Denmark

    DEFF Research Database (Denmark)

    Thodsen, Hans; Hasholt, Bent; Pejrup, Morten

    2004-01-01

    Total phosphorus (TP) concentrations, suspended sediment concentrations (SSC) and wash load have been measured at three river monitoring stations in the River Varde Angstrom system since 1998. This provides the possibility of studying the link between SSC and wash load and concentrations of TP....... Transport rates of TP, suspended sediment and wash load at the three stations, calculated using rating curves, indicate the dependence of TP transport on the transport of suspended sediment and wash load. Two stations are located on tributaries flowing upstream of the third station located at a weir...... at the end of a small impoundment. Transport rates at the upstream stations were 57% higher for suspended sediment and 27% higher for wash load than at the downstream station, while transport of TP was the same. This indicates that phosphorus is transported adhered to the finest grain size fractions that do...

  7. Implications of nitrogen phloem loading for carbon metabolism and transport during Arabidopsis development.

    Science.gov (United States)

    Santiago, James P; Tegeder, Mechthild

    2017-06-01

    Metabolite transport processes and primary metabolism are highly interconnected. This study examined the importance of source-to-sink nitrogen partitioning, and associated nitrogen metabolism for carbon capture, transport and usage. Specifically, Arabidopsis aap8 (AMINO ACID PERMEASE 8) mutant lines were analyzed to resolve the consequences of reduced amino acid phloem loading for source leaf carbon metabolism, sucrose phloem transport and sink development during vegetative and reproductive growth phase. Results showed that decreased amino acid transport had a negative effect on sink development of aap8 lines throughout the life cycle, leading to an overall decrease in plant biomass. During vegetative stage, photosynthesis and carbohydrate levels were decreased in aap8 leaves, while expression of carbon metabolism and transport genes, as well as sucrose phloem transport were not affected despite reduced sink strength. However, when aap8 plants transitioned to reproductive phase, carbon fixation and assimilation as well as sucrose partitioning to siliques were strongly decreased. Overall, this work demonstrates that phloem loading of nitrogen has varying implications for carbon fixation, assimilation and source-to-sink allocation depending on plant growth stage. It further suggests alterations in source-sink relationships, and regulation of carbon metabolism and transport by sink strength in a development-dependent manner. © 2017 Institute of Botany, Chinese Academy of Sciences.

  8. Passive phloem loading and long-distance transport in a synthetic tree-on-a-chip

    DEFF Research Database (Denmark)

    Comtet, Jean; Jensen, Kaare Hartvig; Turgeon, Robert

    2017-01-01

    Vascular plants rely on differences in osmotic pressure to export sugars from regions of synthesis (mature leaves) to sugar sinks (roots, fruits). In this process, known as Münch pressure flow, the loading of sugars from photosynthetic cells to the export conduit (the phloem) is crucial, as it sets...... the pressure head necessary to power long-distance transport. Whereas most herbaceous plants use active mechanisms to increase phloem sugar concentration above that of the photosynthetic cells, in most tree species, for which transport distances are largest, loading seems, counterintuitively, to occur by means......, diffusion-limited export leads to small phloem concentrations and weak scaling of flow rates with hydraulic resistance. We then show that the effective regime of convection-limited export is predominant in plants with large transport resistances and low xylem pressures. Moreover, hydrostatic pressures...

  9. Fate and transport of phenol in a packed bed reactor containing simulated solid waste

    International Nuclear Information System (INIS)

    Saquing, Jovita M.; Knappe, Detlef R.U.; Barlaz, Morton A.

    2012-01-01

    Highlights: ► Anaerobic column experiments were conducted at 37 °C using a simulated waste mixture. ► Sorption and biodegradation model parameters were determined from batch tests. ► HYDRUS simulated well the fate and transport of phenol in a fully saturated waste column. ► The batch biodegradation rate and the rate obtained by inverse modeling differed by a factor of ∼2. ► Tracer tests showed the importance of hydrodynamic parameters to improve model estimates. - Abstract: An assessment of the risk to human health and the environment associated with the presence of organic contaminants (OCs) in landfills necessitates reliable predictive models. The overall objectives of this study were to (1) conduct column experiments to measure the fate and transport of an OC in a simulated solid waste mixture, (2) compare the results of column experiments to model predictions using HYDRUS-1D (version 4.13), a contaminant fate and transport model that can be parameterized to simulate the laboratory experimental system, and (3) determine model input parameters from independently conducted batch experiments. Experiments were conducted in which sorption only and sorption plus biodegradation influenced OC transport. HYDRUS-1D can reasonably simulate the fate and transport of phenol in an anaerobic and fully saturated waste column in which biodegradation and sorption are the prevailing fate processes. The agreement between model predictions and column data was imperfect (i.e., within a factor of two) for the sorption plus biodegradation test and the error almost certainly lies in the difficulty of measuring a biodegradation rate that is applicable to the column conditions. Nevertheless, a biodegradation rate estimate that is within a factor of two or even five may be adequate in the context of a landfill, given the extended retention time and the fact that leachate release will be controlled by the infiltration rate which can be minimized by engineering controls.

  10. Trace element-bearing phases during the solid transport: in-situ characterization and temporal variability in the Loire bed-sediments (France)

    Science.gov (United States)

    Grosbois, Cécile; Courtin-Nomade, Alexandra; Dhivert, Elie; Desmet, Marc; Kunz, Martin

    2013-04-01

    As a result of increased of agriculture, land use, urban areas, industry, traffic and population density, trace element inputs have altered considerably fluvial system (sediment, water quality and biota). The Loire River Basin (117,800 km2, total population of 8.4 Mp in 2010), even if it is considered one of the least human-impacted hydrosystem among the 5 large French basins, has been exposed to multiple sources of metals during the last 150 years, originating from major mining districts (coal and non-ferrous metals) and their associated industrial activities (Grosbois et al, 2012; Dhivert et al, 2013). Two major contamination periods were recorded in several core sediments throughout the basin: urban development of the basin. The limited dilution by detrital material (Loire sediment load between1.5 and 3.5 Mt/y) was an additional cause of such severe contamination. After 1950, river eutrophication was well-marked by the general increase of endogenic calcite in the mid and downstream part of the basin, slightly diluting all major and trace element bulk concentrations by 20% (Grosbois et al, 2012). Since 1980, a generalized and gradual decontamination of bed sediments started while mines were gradually closing, urban waste waters collected and treated in addition to new environmental regulations. They aim to limit metallic pollutant dispersion like industrial recycling of metal wastes and to reduce atmospheric emissions and consequently atmospheric fall out wet and dry deposition In-situ chemical and mineralogical techniques (EPMA, SEM-EDS/ACC system and synchrotron based µXRD) were used (i) to highlight anthropogenic activities by a specific mineralogical signature and (ii) to determine potential effects of post-depositional remobilization and access trace element mobility during the solid transport. Trace element-bearing phases were identified at a micron scale during both mechanical erosion and solid transport. However, some others also reflect post

  11. Numerical modeling of cohesive sediment transport and bed morphology in estuaries

    OpenAIRE

    Leupi, Célestin; Deville, Michel; Altinakar, Mustafa S.

    2007-01-01

    Two major lines of investigation have been pursued in this thesis: (1) More efficient, robust and realistic numerical techniques are designed for the simulation of complex turbulent fluid flows; (2) A new algorithm and its analysis is performed in the context of multiphasic fluid flow, for a cohesive fine-grained sediment (fluid mud) transport in estuaries. Estuaries exist between marine and freshwater system where waters of different physical, chemical and biological composition meet, combin...

  12. An analysis of travel costs on transport of load and nest building in golden hamster.

    Science.gov (United States)

    Guerra, Rogerio F.; Ades, Cesar

    2002-03-28

    We investigated the effects of travel costs on transporting nest material and nest-building activity in golden hamsters. Nest-deprived animals were submitted to run alleys 30, 90 and 180 cm long to access a source containing paper strips as nest material (Experiment 1) or were submitted to the same travel costs in 24-h experimental sessions (Experiment 2). We noted that increased travel costs were related to a decreased number of trips to the source, larger amounts (cm(2)) of nest material transported per trip (although total loads also decreased in longer alleys), longer intervals between trips, and increased time spent at the source and in nest building activity. Foraging efficiency (i.e. size of load divided by the time spent at the source) decreased as a function of travel costs, and animals transported their loads in two fundamental ways: in 30-cm alleys, they simply used their mouth to pull the paper strips, but in 90- or 180-cm alleys they transported the loads in their cheek pouches. The animals were faster when returning to the home-cage and their running speed (cm/s) increased as a function of the length of the alley, showing that animals are under different environmental pressures when searching for resources and subsequently running back with the load to the nest. Both male and female subjects were sensitive to travel costs, but males engaged in nest building activity more promptly and exhibited higher mean performances in most measures. We conclude that nest material is a good reinforcer, and our major results are in accordance with the predictions of microeconomic and optimal foraging theories.

  13. The transport phase of pyrolytic oil exiting a fast fluidized bed reactor

    Science.gov (United States)

    Daugaard, Daren Einar

    An unresolved and debated aspect in the fast pyrolysis of biomass is whether the bio-oil exits as a vapor or as an aerosol from the pyrolytic reactor. The determination of the bio-oil transport phase will have direct and significant impact on the design of fast pyrolysis systems. Optimization of both the removal of particulate matter and collection of bio-oil will require this information. In addition, the success of catalytic reforming of bio-oil to high-value chemicals will depend upon this transport phase. A variety of experimental techniques were used to identify the transport phase. Some tests were as simple as examining the catch of an inline filter while others attempted to deduce whether vapor or aerosol predominated by examining the pressure drop across a flow restriction. In supplementary testing, the effect of char on aerosol formation and the potential impact of cracking during direct contact filtering are evaluated. The study indicates that for pyrolysis of red oak approximately 90 wt-% of the collected bio-oil existed as a liquid aerosol. Conversely, the pyrolysis of corn starch produced bio-oil predominately in the vapor phase at the exit of the reactor. Furthermore, it was determined that the addition of char promotes the production of aerosols during pyrolysis of corn starch. Direct contact filtering of the product stream did not collect any liquids and the bio-oil yield was not significantly reduced indicating measurable cracking or coking did not occur.

  14. TMI-2 transportation program - Design considerations for the NUPAC 125-B cask handling and loading/unloading equipment

    International Nuclear Information System (INIS)

    Schmoker, D.S.; Schmitt, R.C.; Barkanic, R.J.

    1987-01-01

    Removal, transport and receipt of core debris from the damaged reactor at Three Mile Island Unit 2 (TMI-2) required the design of transport cask handling and ''dry'' loading and unloading equipment. The system for ''dry'' (not underwater) loading of the transport cask includes; 1) equipment for handling the cask, 2) equipment for loading core debris canisters into the cask at TMI, and 3) equipment for removing the canisters in a hot cell facility. This paper reviews the technical design considerations operational parameters and summarizes lessons learned in the design, testing, startup and use of the equipment provided for the TMI-2 Transportation Program

  15. Sensitivity of growth characteristics of tidal sand ridges and long bed waves to formulations of bed shear stress, sand transport and tidal forcing : A numerical model study

    NARCIS (Netherlands)

    Yuan, Bing; de Swart, Huib E.; Panadès, Carles

    2016-01-01

    Tidal sand ridges and long bed waves are large-scale bedforms that are observed on continental shelves. They differ in their wavelength and in their orientation with respect to the principal direction of tidal currents. Previous studies indicate that tidal sand ridges appear in areas where tidal

  16. DETERMINATION OF THE LOADING OF CONTAINERS IN MIXED TRAINS WHEN TRANSPORTING BY TRAIN FERRIES

    Directory of Open Access Journals (Sweden)

    A. O. Lovska

    2017-12-01

    Full Text Available Purpose. The study is aimed at determination of the loading of containers in mixed trains when transporting by train ferries. Methodology. In order to achieve the objective the author studied accelerations (as components of the dynamic load influencing the bearing structure of a 1CC standard container located on a flat car during transportation by train ferry. In order to determine accelerations influencing the bearing structure of a container, a mathematical model of the container’s movements under train ferry oscillations was made. The model considered angular displacements of a train ferry relative to the longitudinal axis (bank as being the maximum load on the bearing structure, as well as changes in the container stability relative to the flat car frame. While working out the motion equations three diagrams of interrelation between the container and the flat car located on the train ferry deck were considered: 1 absence of displacements of the flat car and containers relative to the initial place under the train ferry oscillations; 2 with displacements of the flat car under the train ferry oscillations when containers are immovable relative to the flat car frame; 3 with displacements of the flat car relative to the deck and relative to the flat car frame. The differential equations of motion were solved in Mathсad taking into account their reduction to a normal Cauchy problemwith a subsequent integration by the Runge–Kutta method. Findings. Refined values of accelerations influencing the bearing structure of containers located on the flat car while transporting by train ferry were obtained. Originality. The mathematical models of displacements of container bearing structures located on a flat car while transporting by train ferry were proposed. Practical value. The results of investigations can be applied for designing bearing structures of new generation containers, besides they may improve the efficiency of mixed transportation along

  17. Real rock-microfluidic flow cell: A test bed for real-time in situ analysis of flow, transport, and reaction in a subsurface reactive transport environment.

    Science.gov (United States)

    Singh, Rajveer; Sivaguru, Mayandi; Fried, Glenn A; Fouke, Bruce W; Sanford, Robert A; Carrera, Martin; Werth, Charles J

    2017-09-01

    Physical, chemical, and biological interactions between groundwater and sedimentary rock directly control the fundamental subsurface properties such as porosity, permeability, and flow. This is true for a variety of subsurface scenarios, ranging from shallow groundwater aquifers to deeply buried hydrocarbon reservoirs. Microfluidic flow cells are now commonly being used to study these processes at the pore scale in simplified pore structures meant to mimic subsurface reservoirs. However, these micromodels are typically fabricated from glass, silicon, or polydimethylsiloxane (PDMS), and are therefore incapable of replicating the geochemical reactivity and complex three-dimensional pore networks present in subsurface lithologies. To address these limitations, we developed a new microfluidic experimental test bed, herein called the Real Rock-Microfluidic Flow Cell (RR-MFC). A porous 500μm-thick real rock sample of the Clair Group sandstone from a subsurface hydrocarbon reservoir of the North Sea was prepared and mounted inside a PDMS microfluidic channel, creating a dynamic flow-through experimental platform for real-time tracking of subsurface reactive transport. Transmitted and reflected microscopy, cathodoluminescence microscopy, Raman spectroscopy, and confocal laser microscopy techniques were used to (1) determine the mineralogy, geochemistry, and pore networks within the sandstone inserted in the RR-MFC, (2) analyze non-reactive tracer breakthrough in two- and (depth-limited) three-dimensions, and (3) characterize multiphase flow. The RR-MFC is the first microfluidic experimental platform that allows direct visualization of flow and transport in the pore space of a real subsurface reservoir rock sample, and holds potential to advance our understandings of reactive transport and other subsurface processes relevant to pollutant transport and cleanup in groundwater, as well as energy recovery. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. Experience with the loading and transport of fuel assembly transport casks, including CASTOR casks, and the radiation exposure of personnel

    International Nuclear Information System (INIS)

    Bentele, W.; Kinzelmann, T.

    1999-01-01

    In 1997 and 1998, six spent fuel assembly transports started from the nuclear power plant Gemeinschaftskernkraftwerk Neckar (GKN), using CASTOR-V19 casks. Professor Kuni of Marburg University challenged the statement made by the German Federal Office for Radiation Protection (Bundesamt fuer Strahlenschutz (BfS)) based on accepted scientific knowledge, according to which so-called CASTOR transports present no risk, either to the population or to the escorting police units. This paper shows that the collective dose during the loading of the CASTOR casks amounted to 4.5 mSv (gamma and neutrons) per cask at the most, and that the maximum individual dose amounted to 0.26 mSv. In addition to these doses, the collective dose during handling and transport must be considered: this amounted to 0.35 mSv (gamma and neutrons). The dose to the police escort was -2 (limit for surface contamination), presented degrees of contamination >4 Bq cm -2 upon reaching the Valognes/Cogema terminal. However, transport casks coming from French plants also revealed degrees of contamination >4 Bq cm -2 , as well as 'hot spots'. No such contamination was found on NTL 11 casks transported from the GKN to Sellafield. Neither was any increased contamination found upon the arrival of CASTOR-V19 casks transported from GKN to Gorleben or Ahaus. The partially sensationalist media reports were inversely proportional to the actual radiological relevance of the matter. The German Commission on Radiation Protection (SSK) confirmed that the radiological effect of such contaminated spent fuel transports is negligible. (author)

  19. On the influence of suspended sediment transport on the generation of offshore sand waves

    NARCIS (Netherlands)

    Sterlini-Van der Meer, Fenneke; Hulscher, Suzanne J.M.H.; van den Berg, J.; Geurts, Bernardus J.; Clercx, H.J.H.; Uijttewaal, Wim

    2007-01-01

    Sand waves are bed-forms occurring in shallow seas. Although their characteristics are mainly affected by bed load transport, during rough weather suspended sediment transport can influence their characteristics. As a first step to model these influences, we added suspended sediment transport to a

  20. Model behavior and sensitivity in an application of the cohesive bed component of the community sediment transport modeling system for the York River estuary, VA, USA

    Science.gov (United States)

    Fall, Kelsey A.; Harris, Courtney K.; Friedrichs, Carl T.; Rinehimer, J. Paul; Sherwood, Christopher R.

    2014-01-01

    The Community Sediment Transport Modeling System (CSTMS) cohesive bed sub-model that accounts for erosion, deposition, consolidation, and swelling was implemented in a three-dimensional domain to represent the York River estuary, Virginia. The objectives of this paper are to (1) describe the application of the three-dimensional hydrodynamic York Cohesive Bed Model, (2) compare calculations to observations, and (3) investigate sensitivities of the cohesive bed sub-model to user-defined parameters. Model results for summer 2007 showed good agreement with tidal-phase averaged estimates of sediment concentration, bed stress, and current velocity derived from Acoustic Doppler Velocimeter (ADV) field measurements. An important step in implementing the cohesive bed model was specification of both the initial and equilibrium critical shear stress profiles, in addition to choosing other parameters like the consolidation and swelling timescales. This model promises to be a useful tool for investigating the fundamental controls on bed erodibility and settling velocity in the York River, a classical muddy estuary, provided that appropriate data exists to inform the choice of model parameters.

  1. Insights from analog gelatin experiments on the effect of bedding dip on sill morphology and crystal load

    Science.gov (United States)

    Currier, R. M.; Marsh, B. D.; Mittal, T.

    2010-12-01

    The profusion of sills the world over offers a wide spectrum of geologic conditions under which to study emplacement mechanisms and the establishment of the initial conditions governing the subsequent magmatic evolution. Many diabase/dolerite sills are featureless bodies whose only record of solidification is contained in the variation of crystal size. But other sills formed of magma containing crystals entrained from earlier crystallization episodes often show a rich history of interaction between settling crystals and solidification fronts such that the physical history of differentiation can be readily observed. This work explores this aspect of sills using visco-elastic gelatin as country rock, molten wax as magma and tiny particles as phenocrysts. Magmatic sills form mechanically, when an ascending dike encounters a more rigid layer, is diverted laterally, and systematically inflates as guided along by the interface. In this manner, sills grow about the injection site, and can do so symmetrically or asymmetrically. The degree of asymmetry is affected by the dip angle of the interface. An angled interface implies a directional pressure gradient, and magma flows preferentially in the direction of decreasing pressure, in this case, up tilt. So, the greater the tilt, the greater the asymmetry. By experimentally producing sills in layered, tilted, media, we have investigated the influence of bed dip on sill morphology. Experiments were performed by injecting wax and particles into gelatin where the layers were poured at set angles to mimic tilted bedding. In addition to its visco-elastic properties, gelatin also has the added benefit of transparency, allowing for direct observation during the experiment and can be washed away later to reveal the exact details of the remaining solid. To emulate magma as a multi-phase slurry, a magmatic analog was used consisting of a mixture of molten wax near its liquidus and ultrafine glitter. Wax solidifies in response to thermal

  2. Near-bed observations of high-concentration sediment transport in the Changjiang Estuary

    Science.gov (United States)

    Zhou, Z.; Ge, J.; Ding, P.

    2017-12-01

    The North Passage, the core of turbidity maximum in the Changjiang Estuary, is now under the strong sedimentation due to the abundant sediment supply from the upstream Changjiang River and the river-tide interacted dynamics. Recent studies suggested that strong siltation could be attributed to bottom high-concentration sediment transport, which however is very difficult to be detected and observed by vessel-anchored survey methods. To better understand the mechanisms of sediment transport and deposition in the channel region of the North Passage and its adjacent areas, we conducted continuous field observations which covered spring and neap tide period in the wintertime of 2016, the summertime of 2015 and 2017, focusing on near-bottom sediment transport. Tripods mounted with multiple instruments, including up-looking and down-looking Acoustic Doppler Current Profilers(ADCP), Vector Current Meter(ADV), Optical Backscatter Sensor(OBS), ASM, ALEC and RBR were used to observe the near-bottom physical process and its induced sediment dynamics. Results of these observations clearly described the current-wave-sediment interaction, which produced different patterns of bottom mud suspension at different tripods. Both hydrodynamic features and suspended sediment showed variations between spring and neap tide. Taking data of 2016 as an example, averaged suspended sediment concentration(SSC) at two tripods was 1.52 g/L and 2.13 g/L during the neap tide, 4.51 g/L and 5.75 g/L with the peak value reaching 25 g/L during the spring tide. At the tripod which was closer to the channel region, three peaks of SSC during the spring tide occurred near the flood slack with notable salinity increase, indicating the impact of saltwater intrusion on the bottom hydrodynamics. The results showed the occurrence of high-concentration suspended sediment was probably related to combined effects of bottom salinity intrusion, turbulent kinetic energy(TKE) and local stratification due to density

  3. Effect of loading types on performance characteristics of a trickle-bed bioreactor and biofilter during styrene/acetone vapor biofiltration.

    Science.gov (United States)

    Halecky, Martin; Paca, Jan; Kozliak, Evguenii; Jones, Kim

    2016-07-02

    A 2:1 (w/w) mixture of styrene (STY) and acetone (AC) was subjected to lab-scale biofiltration under varied loading in both a trickle bed reactor (TBR) and biofilter (BF) to investigate substrate interactions and determine the limits of biofiltration efficiency of typical binary air pollutant mixtures containing both hydrophobic and polar components. A comparison of the STY/AC mixture degradation in the TBR and BF revealed higher pollutant removal efficiencies and degradation rates in the TBR, with the pollutant concentrations increasing up to the overloading limit. The maximum styrene degradation rates were 12 and 8 gc m(-3) h(-1) for the TBR and BF, respectively. However, the order of performance switched in favor of the BF when the loading was conducted by increasing air flow rate while keeping the inlet styrene concentration (Cin) constant in contrast to loading by increasing Cin. This switch may be due to a drastic difference in the effective surface area between these two reactors, so the biofilter becomes the reactor of choice when the rate-limiting step switches from biochemical processes to mass transfer by changing the loading mode. The presence of acetone in the mixture decreased the efficiency of styrene degradation and its degradation rate at high loadings. When the overloading was lifted by lowering the pollutant inlet concentrations, short-term back-stripping of both substrates in both reactors into the outlet air was observed, with a subsequent gradual recovery taking several hours and days in the BF and TBR, respectively. Removal of excess biomass from the TBR significantly improved the reactor performance. Identification of the cultivable strains, which was performed on Day 763 of continuous operation, showed the presence of 7 G(-) bacteria, 2 G(+) bacteria and 4 fungi. Flies and larvae of Lycoriella nigripes survived half a year of the biofilter operation by feeding on the biofilm resulting in the maintenance of a nearly constant pressure drop.

  4. Metals transport in the Sacramento River, California, 1996-1997; Volume 2: Interpretation of metal loads

    Science.gov (United States)

    Alpers, Charles N.; Antweiler, Ronald C.; Taylor, Howard E.; Dileanis, Peter D.; Domagalski, Joseph L.

    2000-01-01

    Metals transport in the Sacramento River, northern California, from July 1996 to June 1997 was evaluated in terms of metal loads from samples of water and suspended colloids that were collected on up to six occasions at 13 sites in the Sacramento River Basin. Four of the sampling periods (July, September, and November 1996; and May-June 1997) took place during relatively low-flow conditions and two sampling periods (December 1996 and January 1997) took place during high-flow and flooding conditions, respectively. This study focused primarily on loads of cadmium, copper, lead, and zinc, with secondary emphasis on loads of aluminum, iron, and mercury.Trace metals in acid mine drainage from abandoned and inactive base-metal mines, in the East and West Shasta mining districts, enter the Sacramento River system in predominantly dissolved form into both Shasta Lake and Keswick Reservoir. The proportion of trace metals that was dissolved (as opposed to colloidal) in samples collected at Shasta and Keswick dams decreased in the order zinc ≈ cadmium > copper > lead. At four sampling sites on the Sacramento River--71, 256, 360, and 412 kilometers downstream of Keswick Dam--trace-metal loads were predominantly colloidal during both high- and low-flow conditions. The proportion of total cadmium, copper, lead, and zinc loads transported to San Francisco Bay and the Sacramento-San Joaquin Delta estuary (referred to as the Bay-Delta) that is associated with mineralized areas was estimated by dividing loads at Keswick Dam by loads 412 kilometers downstream at Freeport and the Yolo Bypass. During moderately high flows in December 1996, mineralization-related total (dissolved + colloidal) trace-metal loads to the Bay-Delta (as a percentage of total loads measured downstream) were cadmium, 87 percent; copper, 35 percent; lead, 10 percent; and zinc, 51 percent. During flood conditions in January 1997 loads were cadmium, 22 percent; copper, 11 percent; lead, 2 percent; and zinc, 15

  5. New ZnO-based regenerable sulfur sorbents for fluid-bed/transport reactor applications

    Energy Technology Data Exchange (ETDEWEB)

    Slimane, R.B.; Williams, B.E. [Inst. of Gas Technology, Des Plaines, IL (United States)

    2002-11-13

    A new sorbent synthesis technique has been developed at GTI, based on sol-gel processing of inorganic and organic precursors, for the preparation of ZnO-based regenerable sulfur sorbents with unique properties that could not be attained with 'conventional' sorbent preparation methods such as coprecipitation or solid-oxide mixing followed by extrusion, granulation, or spray drying. Unlike these techniques, which require very high calcination temperatures to impart physical strength to sorbents, sol-gel processing offers the unique capability of producing sintering at exceptionally low temperatures. As a result, materials with high surface areas, small pore sizes, and very high resistance to attrition can be synthesized. Sorbents prepared with this new technique demonstrated attrition indices that are well below the stringent requirement of the transport reactor of about 4% and effective capacity for sulfur absorption exceeding 8 g of S 1100 g of sorbent. In addition, these sorbents demonstrated regenerability at temperatures that are lower than those required by typical zinc titanates. On the basis of chemical analysis, physical characterization, attrition resistance determination, and evaluation of chemical reactivity and regenerability, the exceptional characteristics of this new class of zinc-based sorbents are demonstrated in this paper.

  6. The use of the carbon/nitrogen ratio and specific organic loading rate as tools for improving biohydrogen production in fixed-bed reactors

    Directory of Open Access Journals (Sweden)

    Mélida del Pilar Anzola-Rojas

    2015-03-01

    Full Text Available This study assessed the effect of the carbon/nitrogen (C/N ratio on the hydrogen production from sucrose-based synthetic wastewater in upflow fixed-bed anaerobic reactors. C/N ratios of 40, 90, 140, and 190 (g C/g N were studied using sucrose and urea as the carbon and nitrogen sources, respectively. An optimum hydrogen yield of 3.5 mol H2 mol−1 sucrose was obtained for a C/N ratio of 137 by means of mathematical adjustment. For all C/N ratios, the sucrose removal efficiency reached values greater than 80% and was stable after the transient stage. However, biogas production was not stable at all C/N ratios as a consequence of the continuous decreasing of the specific organic loading rate (SOLR when the biomass accumulated in the fixed-bed, causing the proliferation of H2-consuming microorganisms. It was found that the application of a constant SOLR of 6.0 g sucrose g−1 VSS d−1 stabilized the system.

  7. Partitioning and analyzing temporal variability of wash and bed ...

    Indian Academy of Sciences (India)

    leads to reduction in storage capacity of dams, increases flood risk, deteriorates water quality and ultimately results .... results showed that the capacity of bed material load transport was controlled by hydraulic conditions ... oped mainly for livestock grazing in uplands. Land covers comprise Fagus orientalis, Alnus sp., Acer.

  8. An exact model for airline flight network optimization based on transport momentum and aircraft load factor

    Directory of Open Access Journals (Sweden)

    Daniel Jorge Caetano

    2017-12-01

    Full Text Available The problem of airline flight network optimization can be split into subproblems such as Schedule Generation (SG and Fleet Assignment (FA, solved in consecutive steps or in an integrated way, usually based on monetary costs and revenue forecasts. A linear pro­gramming model to solve SG and FA in an integrated way is presented, but with an al­ternative approach based on transport momentum and aircraft load factor. This alterna­tive approach relies on demand forecast and allows obtaining solutions considering min­imum average load factors. Results of the proposed model applications to instances of a regional Brazilian airline are presented. The comparison of the schedules generated by the proposed approach against those obtained by applying a model based on mone­tary costs and revenue forecasts demonstrates the validity of this alternative approach for airlines network planning.

  9. Loading and transport of high-active waste (HAW) with the TN85 flask in 2008

    Energy Technology Data Exchange (ETDEWEB)

    Rys, Michael; Horn, Thomas; Graf, Wilhelm [GNS Gesellschaft fuer Nuklear-Service mbH (Germany); Bonface, Jean-Michael [TN International, Montigny-le-Bretonneux (France)

    2009-07-01

    As a part of the operation of nuclear power plants, it is essential to safely manage the radioactive waste. With new developments in science and technology, it is a dynamic process to adapt procedures, equipment and flasks to be used in the future. This is a task for specialists - a task for GNS Gesellschaft fuer Nuklear-Service mbH and for TN International. Until 1994 reprocessing of spent fuel from German nuclear power plants was mandatory for the Utilities (EVU) in Germany. Basis for the reprocessing was the German Atomic Act. The German Utilities concluded contracts on reprocessing with Compagnie Generale des Matieres Nucleaires (COGEMA, now AREVA NC) in France and British Nuclear Fuels plc (BNFL, now INS) in England. The total amount to be reprocessed comes to 5309 t HM contracted to AREVA NC and 768 t HM contracted to INS. The waste generated from reprocessing - or an equivalent amount of radioactive material - has to be returned to the country of origin. In 1979 already an exchange of notes took place between the German and the French government with the obligation of both sides to enable and support the return of reprocessing residues or equivalents. The return of high-active waste (HAW) from France has started in 1996 with the first attribution of 28 glass canisters (one flask) to German Utilities by AREVA NC. Until 2007, 75 flasks loaded with vitrified residue (VR) canisters have been transported to Gorleben. For these transports CASTOR {sup registered} HAW 20/28 CG flasks have been used. This presentation will give some background information about the last HAW transport in 2008 with the new flask generation of the type TN85. It will also describe the assembly of the new flask, the preparation of the flask for the loading campaign as well as the loading procedure. (orig.)

  10. The anatomy of effective discharge: the dynamics of coarse sediment transport revealed using continuous bedload monitoring in a gravel-bed river during a very wet year

    OpenAIRE

    Downs, Peter W.; Soar, Philip J.; Taylor, Alex

    2015-01-01

    Indirect, passive approaches for monitoring coarse bedload transport could allow cheaper, safer, higher-resolution, longer-term data that revolutionises bedload understanding and informs river management. Here, insights provided by seismic impact plates in a downstream reach of a flashy gravel-bed river (River Avon, Devon, UK) are explored in the context of plate performance. Monitoring of a centrally-situated plate (IP1) during an extremely wet 12-month period demonstrated that impacts were ...

  11. Quasi-Three-Dimensional Mathematical Modeling of Morphological Processes Based on Equilibrium Sediment Transport

    Science.gov (United States)

    Charafi, My. M.; Sadok, A.; Kamal, A.; Menai, A.

    A quasi-three-dimensional mathematical model has been developed to study the morphological processes based on equilibrium sediment transport method. The flow velocities are computed by a two-dimensional horizontal depth-averaged flow model (H2D) in combination with logarithmic velocity profiles. The transport of sediment particles by a flow water has been considered in the form of bed load and suspended load. The bed load transport rate is defined as the transport of particles by rolling and saltating along the bed surface and is given by the Van Rijn relationship (1987). The equilibrium suspended load transport is described in terms of an equilibrium sediment concentration profile (ce) and a logarithmic velocity (u). Based on the equilibrium transport, the bed change rate is given by integration of the sediment mass-balance equation. The model results have been compared with a Van Rijn results (equilibrium approach) and good agreement has been found.

  12. [The approach to the regulation of mercury according to the content of its termoforms in soils and bed loads].

    Science.gov (United States)

    Bogdanov, N A

    also developed ranking scales of the ecological and hygienic condition of the land areas and surface water bodies. As a result, on the base of such approach to the regulation of Hg the information value of assessments of mercury contamination of land significantly increased. At the objects of assessments there were identified following areas: foci of the manifestation of Hg hypolimnetic emanations on the landscape surface - dispersion halos in the areas of the Earth crust fracture (the dome of the Astrakhan gas condensate field); environmentally dangerous (sometimes even at a low total content of Hg) parts of cities, towns, their districts, as well as beds of watercourses and water reservoirs bottom (the Volga river valley and delta, the Lefortovo quarter in Moscow). There was also diagnosed the threshold of the background distribution of gross Hg content detected = 0.2-0.3 mg/kg. Its magnitude is consistent with domestic and abroad safe levels of Hg accumulation in soils = 0.3-0.4 mg/kg. The approach provides the differentiation of the environmental hazard lands. Technology of the approach can be used in the development of normative Document for the diagnosis of environmental and sanitary condition of territories in the system of Classifications of hazard of waste, in decontamination of territories, water areas and land zoning according to the criteria of natural or anthropogenic Hg accumulation.

  13. Improving Log Loading Efficiency for Improved Sustainable Transport within the Irish Forest and Biomass Sectors

    Directory of Open Access Journals (Sweden)

    Amanda Sosa

    2015-03-01

    Full Text Available In Ireland, timber and biomass haulage faces the challenge of transporting enough material within strict legal dimensions and gross vehicle weights restrictions for trucks and trailers. The objective of this study was to develop a method to control payload weight by knowing the moisture content of the wood. Weights, volumes, and moisture content were gathered from 100 truckloads of Sitka spruce pulpwood. Truck volume and weight utilization patterns were analyzed based on stacked volume, truck volume, and weights recorded from the weighbridge. Solid/bulk volume conversion factors for the truckloads were estimated indicating the truck’s solid volume capacity to be filled. Trucks were grouped into five conditions based on their configuration—volume capacity and legal maximum payload. A loaded volume fraction was estimated to assess the optimal volume capacity and stanchion height at which the trucks should be loaded. Results showed that 100% of the trucks presented volume underutilization, with a maximum of 27.5 m3 (only 39.85% volume capacity. In contrast, 67% of trucks were overweight while the remaining 33% were under the legal maximum weight. The average solid/bulk volume conversion factor was 0.66 ± 0.013 at 95% confidence level. Depending on the conditions, trucks can be filled to 100% of their volume capacity with wood at an MC from 29% to 55%. The minimum truck volume capacity utilization was 45%. This methodology can be used by truck hauliers, enabling them to determine in-forest the optimum volume and weight of wood to be transported by knowing the moisture content (MC, the wood specie, and using the height of the stanchions of the trailer as reference when loading the truck.

  14. Changing river channels: The roles of hydrological processes, plants and pioneer fluvial landforms in humid temperate, mixed load, gravel bed rivers

    Science.gov (United States)

    Gurnell, Angela M.; Bertoldi, Walter; Corenblit, Dov

    2012-02-01

    The fluvial riparian and aquatic patch mosaic varies along rivers according to geomorphological setting, hydrological regime, sediment supply and surface-groundwater connectivity. This relation between physical processes and plants is not unidirectional. Once established, riparian and aquatic plants frequently act as physical ecosystem engineers by trapping and stabilising sediments, organic matter and the propagules of other plant species, modifying the local sedimentary and morphological environment by driving the development of landforms and associated habitats, and so facilitating the rapid establishment of other plants that can in turn reinforce the development of landforms such as river banks, vegetated islands and floodplains. This paper reviews knowledge on the hydrogeomorphological significance of riparian and aquatic vegetation with a particular emphasis on humid temperate, mixed load, gravel bed, floodplain rivers. First, we investigate how vegetation dynamics across river margins are governed by hydrological processes that can both promote riparian vegetation growth and disturb and destroy riparian and aquatic vegetation. We show, with some simple numerical modeling, that different combinations of moisture supply and flow disturbance have the potential to generate many different responses in the lateral distribution of vegetation biomass along river corridors. Second, building on the varied lateral biomass distributions that are primarily dictated by hydrological processes, we review research evaluating characteristic vegetation-mediated landform development. We investigate aquatic and riparian plants acting as physical ecosystem engineers by creating and modifying habitats in river systems with sufficient suspended sediment supply for habitat or landform building. These plants have a crucial impact on sediment stabilisation and pioneer landform building along the interface between plant (resistance) dominated and fluvial-disturbance (force) dominated

  15. Assessment of the transportation route of oversize and excessive loads in relation to the load-bearing capacity of existing bridges

    Science.gov (United States)

    Doležel, Jiří; Novák, Drahomír; Petrů, Jan

    2017-09-01

    Transportation routes of oversize and excessive loads are currently planned in relation to ensure the transit of a vehicle through critical points on the road. Critical points are level-intersection of roads, bridges etc. This article presents a comprehensive procedure to determine a reliability and a load-bearing capacity level of the existing bridges on highways and roads using the advanced methods of reliability analysis based on simulation techniques of Monte Carlo type in combination with nonlinear finite element method analysis. The safety index is considered as a main criterion of the reliability level of the existing construction structures and the index is described in current structural design standards, e.g. ISO and Eurocode. An example of a single-span slab bridge made of precast prestressed concrete girders of the 60 year current time and its load bearing capacity is set for the ultimate limit state and serviceability limit state. The structure’s design load capacity was estimated by the full probability nonlinear MKP analysis using a simulation technique Latin Hypercube Sampling (LHS). Load-bearing capacity values based on a fully probabilistic analysis are compared with the load-bearing capacity levels which were estimated by deterministic methods of a critical section of the most loaded girders.

  16. Breakup and reestablishment of the armour layer in a large gravel-bed river below dams: The lower Ebro

    Science.gov (United States)

    Vericat, Damia; Batalla, Ramon J.; Garcia, Celso

    2006-06-01

    Changes in armour layer during floods under supply limited conditions are little known. This paper describes the breakup and the reestablishment of the bed armour layer in the regulated gravel-bed Ebro River during a flooding period. The study was conducted over a 28-km study reach from 2002 to 2004. The surface, subsurface and bed load grain size distribution constitute the bases for the analysis of bed-armouring dynamics. The results indicate that the magnitude of floods controlled the degree of armouring of the river bed. The initial mean armouring ratio was 2.3, with maximum values reaching 4.4. Floods in the winter of 2002-2003 ( Q8) caused the breakup of the armour layer in several sections. This resulted in the erratic bed load pattern observed during the December 2002 flushing flow and in the increase in bed load transport during successive events. Most grain size classes were entrained and transported, causing river bed incision. The mean armouring ratio decreased to 1.9. In contrast, during low magnitude floods in 2003-2004 ( Q2), the coarsest fractions (64 mm) did not take part in the bed load while finer particles were winnowed, thus surface deposits coarsened. As a result, the armour layer was reestablished (i.e., the mean armouring ratio increased to 2.3), and the supply of subsurface sediment decreased. The supply and transport of bed material appear to be in balance in the river reach immediately below the dam. In contrast, the transport of medium and finer size classes in the downstream reaches was higher than their supply from upstream, a phenomenon that progressively reduced their availability in the river bed surface, hence the armour layer reworking.

  17. Performance and design considerations for an anaerobic moving bed biofilm reactor treating brewery wastewater: Impact of surface area loading rate and temperature.

    Science.gov (United States)

    di Biase, A; Devlin, T R; Kowalski, M S; Oleszkiewicz, J A

    2017-06-05

    Three 4 L anaerobic moving bed biofilm reactors (AMBBR) treated brewery wastewater with AC920 media providing 680 m 2 protected surface area per m 3 of media. Different hydraulic retention times (HRT; 24, 18, 12, 10, 8 and 6 h) at 40% media fill and 35 °C, as well as different temperatures (15, 25 and 35 °C) at 50% media fill and 18 h HRT were examined. Best performance at 35 °C and 40% media fill was observed when HRT was 18 h, which corresponded with 92% removal of soluble COD (sCOD). Organic loading rates (OLR) above 24 kg-COD m -3 d -1 decreased performance below 80% sCOD removal at 35 °C and 40% media fill. The reason was confirmed to be that surface area loading rates (SALR) above 50 g-sCOD m -2 d -1 caused excessive biofilm thickness that filled up internal channels of the media, leading to mass transfer limitations. Temperature had a very significant impact on process performance with 50% media fill and 18 h HRT. Biomass concentrations were significantly higher at lower temperatures. At 15 °C the mass of volatile solids (VS) was more than three times higher than at 35 °C for the same OLR. Biofilms acclimated to 25 °C and 15 °C achieved removal of 80% sCOD at SALR of 10 g-sCOD m -2 d -1 and 1.0 g-sCOD m -2 d -1 , respectively. Even though biomass concentrations were higher at lower temperature, biofilm acclimated to 25 °C and 15 °C performed significantly slower than that acclimated to 35 °C. Copyright © 2017 Elsevier Ltd. All rights reserved.

  18. Influence of Boulder Concentration on Turbulence and Sediment Transport in Open-Channel Flow Over Submerged Boulders

    Science.gov (United States)

    Fang, H. W.; Liu, Y.; Stoesser, T.

    2017-12-01

    In this paper the effects of boulder concentration on hydrodynamics and local and reach-averaged sediment transport properties with a flow over submerged boulder arrays are investigated. Four numerical simulations are performed in which the boulders' streamwise spacings are varied. Statistics of near-bed velocity, Reynolds shear stresses, and turbulent events are collected and used to predict bed load transport rates. The results demonstrate that the presence of boulders at various interboulder spacings altered the flow field in their vicinity causing (1) flow deceleration, wake formation, and vortex shedding; (2) enhanced outward and inward interaction turbulence events downstream of the boulders; and (3) a redistribution of the local bed shear stress around the boulder consisting of pockets of high and low bed shear stresses. The spatial variety of the predicted bed load transport rate qs based on local bed shear stress is visualized and is shown to depend greatly on the boulder concentration. Quantitative bed load transport calculations demonstrate that the reach-averaged bed load transport rate may be overestimated by up to 25 times when including the form-drag-generated shear stress of the immobile boulders in the chosen bed load formula. Further, the reach-averaged bed load transport rate may be underestimated by 11% if the local variability of the bed shear stress is not accounted for. Finally, it is shown that for the small-spaced boulder array, the bed load transport rates should no longer be predicted using a normal distribution with standard deviation of the shear stress distribution σ.

  19. A deceleration system for near-diameter spheres in pipeline transportation in a pebble bed reactor based on the resistance of a pneumatic cushion

    International Nuclear Information System (INIS)

    Liu, Hongbing; He, Ayada; Du, Dong; Wang, Xin; Zhang, Haiquan

    2014-01-01

    Highlights: • A deceleration system for fuel transportation in a pebble bed reactor is designed. • Dynamic analysis and motion analysis of the deceleration process are conducted. • The effectiveness of the system is verified by the analysis and the experiment. • Some key design parameters are studied to achieve effective deceleration. • This research provides a guide for the design of a pebble bed reactor. - Abstract: The fuel elements cycle occurring inside and outside the core of a pebble bed reactor is carried out by pneumatic conveying. In some processes of conveyance, it is necessary to reduce the velocity of the moving fuel element in a short time to avoid damage to the fuel elements and the equipment. In this research, a deceleration system for near-diameter spheres in pipeline transportation based on the resistance of a pneumatic cushion is designed to achieve an effective and reliable deceleration process. Dynamic analysis and motion analysis of the deceleration process are conducted. The results show that when the fuel element is moving in the deceleration pipeline, the gas in the pipeline is compressed to create a pneumatic cushion which resists the movement of the fuel element. In this way, the velocity of the fuel element is decreased to below the target value. During this process, the deceleration is steady and reliable. On this basis some key design parameters are studied, such as the deceleration pipeline length, the ratio of the diameter of the fuel element to the internal diameter of the pipeline, etc. The experimental results are generally consistent with the analysis and demonstrate the considerable effectiveness of the deceleration process as well. This research provides a guide for the design of the fuel elements cycling system in a pebble bed reactor along with the optimization of its control

  20. Temperature and press load stimulation on thermal transport in fibrous and porous composite insulators

    International Nuclear Information System (INIS)

    Rehman, M.A.; Maqsood, A.

    2006-01-01

    Thermal transport properties of synthetic pliable insulators are measured as a function of applied pressure at constant temperatures. Advantageous Transient Plane Source (ATPS) method is used for the simultaneous measurement of thermal conductivity and thermal diffusivity of these materials and heat capacity per unit volume is then calculated. Three samples namely foam, closed cell foam and fiber glass are subjected to press load, taking into account the flexibility and sustainability of the samples and the requirements of the technique used. The thermal data of the samples were determined within the temperature range (300-414K) and pressure range (Normal -15kPa). These materials are used for thermal insulation and temperature control of air-conditioned space, acoustic and sound insulation, agriculture and fishery, sports and leisure goods, building and civil engineering, industrial packaging cold storage ware house, boiler work and other electric appliances, so they are helpful in reducing energy losses. (author)

  1. Effect of light-load resistance exercise on postprandial amino acid transporter expression in elderly men

    DEFF Research Database (Denmark)

    Agergaard, Jakob; Bülow, Jacob; Jensen, Jacob K

    2017-01-01

    An impaired amino acid sensing is associated with age-related loss of skeletal muscle mass. We tested whether light-load resistance exercise (LL-RE) affects postprandial amino acid transporter (AAT) expression in aging skeletal muscle. Untrained, healthy men (age: +65 years) were subjected to 13 h...... and 12 g at 7 h) (BOLUS, N = 10), or hourly isocaloric maltodextrin drinks (placebo, N = 10). Quadriceps muscle biopsies were taken at 0, 3, 7, and 10 h postexercise from both the resting and exercised leg, from which the membrane protein and mRNA expression of select AATs were analyzed by Western Blot...... decrease in SNAT2 mRNA expression was observed. LL-RE increased membrane-associated AAT protein expression and mRNA expression. Altered AAT protein expression was only seen in groups that ingested whey protein, with the greatest effect observed after hourly feeding. This points toward an importance of AATs...

  2. Does Moss Grow on a Rolling Stone? The Influence of Precipitation Phase on Streamflow Characteristics, Bed Particle Transport and Periphyton Development in 18 Mountain Channels, Central Idaho

    Science.gov (United States)

    Tennant, C.; Crosby, B. T.; Baxter, C.

    2012-12-01

    It has been suggested that linked ecological and geomorphological systems exhibit complex and non-linear response to disturbance. However, quantifying the response of these systems is complicated by identifying the relevant linkages between system components and by variability in time scale adjustments. To help elucidate some of these complexities we characterized the influence of streamflow and bed-substrate mobility on periphyton assemblage development. Study catchments are subdivided into 3 categories based on the fraction of precipitation that fell as rain vs. snow. The categories are rain-dominated (RD), mixed rain-snow (MRS) and snow-dominated (SD). Three water years of streamflow data demonstrate that RD catchments experienced the largest inter-regime and inter-annual variability in streamflow conditions. RD sites were characterized by flashy responses to frequent precipitation events during wet winter and spring months and experienced channel drying during the summer. Runoff in MRS and SD catchments was characterized by much higher magnitude, longer duration flow events in early and mid-summer. Hydrologic results suggest that RD watersheds limit periphyton mass because of drought conditions and that MRS and SD channels control the temporal scale of periphyton development via long duration, high magnitude flood events that transport bed sediments and disrupt primary production. Results from our rock-tracing experiment indicate that assessments of biological disturbance based on hydrologic metrics alone miss important details of the characteristics of physical disturbance within channels. Channels within RD catchments appear to be in disequilibrium because of variability in the frequency and consistency of hydrologic events capable of mobilizing bed particles. Wet winters resulted in frequent and flashy streamflow events that likely caused bedload transport, whereas drier winters caused few streamflow events and subsequently little to no bedload transport

  3. Transport of jundiá Rhamdia quelen juveniles at different loading densities: water quality and blood parameters

    Directory of Open Access Journals (Sweden)

    Paulo César Falanghe Carneiro

    Full Text Available Fish transportation is a common practice on fish farms and is considered to be a stressor that could negatively affect fish health. The objective of this study was to evaluate several physiological responses of stress in jundiá caused by transport at different loading densities. Jundiá juveniles were placed in plastic bags on a mechanical transport simulator for four hours at four different loading densities (75, 150, 250 and 350 g L-1 and then transferred to sixteen 80-L plastic boxes for 96 hours after transport. Water samples were collected before and after transport to measure dissolved oxygen, temperature, pH and ammonia levels. Blood samples were taken at departure and arrival, as well as at 24 and 96 hours after transport to monitor cortisol, glucose, ammonia, chloride and hematocrit levels. Water ammonia levels were found to increase gradually as loading densities increased. Plasma ammonia was higher after transport in fish from all treatments. Compared to initial values, substantial increases in plasma cortisol and ammonia levels were detected mainly in those fish submitted to the highest loading density. Blood glucose appeared to be positively influenced by the increase of transport densities. No statistical differences were observed in any of the other blood parameters. The costs in fish culture, as in other animal production systems, must be minimized and fish producers depend on optimal techniques to ensure better profit. Therefore, based on fish survival and the physiological indicators determined in the present study, especially during recovery, the best density at which to transport jundiá in plastic bags for four hours is about 350 g/L.

  4. Effects of trail gradient on leaf tissue transport and load size selection in leaf-cutter ants

    OpenAIRE

    O. T. Lewis; M. Martin; T. J. Czaczkes

    2008-01-01

    Leaf-cutter ants in the genus Atta are frequent model organisms in studies of central-place foraging. Workers carry leaf fragments from the foraging site to the nest. Larger workers carry heavier loads, but it has been noted repeatedly that workers typically carry fragments lower in mass than appropriate to maximize leaf tissue transport. Here, we suggest and test a previously unconsidered explanation for this discrepancy. Previous calculations of rate-maximizing load sizes have been based on...

  5. Myosin VI as a transporter and an anchor: A model for kinetics of the motor under load

    Science.gov (United States)

    Chuan, Peiying; Spudich, James; Dunn, Alexander

    2010-03-01

    Myosin VI is an actin-based motor that is thought to function both as a transporter and an anchor in vivo. In an earlier study (Altman et al, Cell 2004), inhibition of myosin VI stepping kinetics by load applied using an optical trap was observed at saturating ATP and low ADP concentrations (ADP binding increases exponentially with load was proposed. This model predicts that myosin VI functions primarily as an anchor at loads greater than ˜0.5 pN under physiological nucleotide conditions, which is potentially inconsistent with its roles in vivo. Here we present myosin VI stepping data taken at a variety of applied loads and ADP concentrations, and show that the Altman model only holds at low ADP concentrations. At higher, physiologically relevant ADP concentrations under load we observe dwell times that are an order of magnitude smaller than predicted by the Altman model. We present a modified model in which applied load alters the equilibrium between two myosin VI states with different nucleotide affinities. This new kinetic scheme accurately describes myosin VI behavior at various nucleotide conditions under a large range of loads, and explains how the motor is able to carry out its roles in vivo, both as a force-generating transporter and as an anchor.

  6. Refrigeration logistics operations and perishable transport costs in groupage loads: an application for Spanish exports in Europe

    OpenAIRE

    Andrés González-Moralejo, Silvia

    2012-01-01

    Creative Commons Attribution License [EN] In this paper, we analyze the current Spanish tariff system as applied by low-temperature distribution companies on transport in part loads of perishable freight that are destined to Spain’s main European export markets. Using 2008 data that have been directly obtained from a sample of transport companies, the price structure is formulated by making a distinction between ordinary and final prices and their respective variables. Next, ...

  7. Application of SELECT and SWAT models to simulate source load, fate, and transport of fecal bacteria in watersheds.

    Science.gov (United States)

    Ranatunga, T.

    2017-12-01

    Modeling of fate and transport of fecal bacteria in a watershed is a processed based approach that considers releases from manure, point sources, and septic systems. Overland transport with water and sediments, infiltration into soils, transport in the vadose zone and groundwater, die-off and growth processes, and in-stream transport are considered as the other major processes in bacteria simulation. This presentation will discuss a simulation of fecal indicator bacteria source loading and in-stream conditions of a non-tidal watershed (Cedar Bayou Watershed) in South Central Texas using two models; Spatially Explicit Load Enrichment Calculation Tool (SELECT) and Soil and Water Assessment Tool (SWAT). Furthermore, it will discuss a probable approach of bacteria source load reduction in order to meet the water quality standards in the streams. The selected watershed is listed as having levels of fecal indicator bacteria that posed a risk for contact recreation and wading by the Texas Commission of Environmental Quality (TCEQ). The SELECT modeling approach was used in estimating the bacteria source loading from land categories. Major bacteria sources considered were, failing septic systems, discharges from wastewater treatment facilities, excreta from livestock (Cattle, Horses, Sheep and Goat), excreta from Wildlife (Feral Hogs, and Deer), Pet waste (mainly from Dogs), and runoff from urban surfaces. The estimated source loads from SELECT model were input to the SWAT model, and simulate the bacteria transport through the land and in-stream. The calibrated SWAT model was then used to estimate the indicator bacteria in-stream concentrations for future years based on regional land use, population and household forecast (up to 2040). Based on the reductions required to meet the water quality standards in-stream, the corresponding required source load reductions were estimated.

  8. Effect of Mass-Transport Limitations on the Performance of a Packed Bed Membrane Reactor for Partial Oxidations. Intraparticle Mass Transport

    NARCIS (Netherlands)

    van Sint Annaland, M.; Kurten, U.; Kuipers, J.A.M.

    2007-01-01

    For partial oxidation systems, where the reaction order in oxygen of the formation rate of the target product is smaller than the reaction order in oxygen of the consecutive reaction rate toward the waste product, a packed bed membrane reactor can be applied to distributively dose oxygen along the

  9. Anomalous Dispersion in a Sand Bed River

    Science.gov (United States)

    Bradley, D. N.; Tucker, G. E.; Benson, D. M.

    2009-04-01

    There has been a recent surge of interest in non-local, heavy-tailed models of sediment transport and dispersion that are governed by fractional order differential equations. These models have a firm mathematical foundation and have been successfully applied in a variety of transport systems, but their use in geomorphology has been minimal because the data required to validate the models is difficult to acquire. We use data from a nearly 50-year-old tracer experiment to test a fluvial bed load transport model with a two unique features. First, the model uses a heavy-tailed particle velocity distribution with a divergent second moment to reproduce the anomalously high fraction of tracer mass observed in the downstream tail of the spatial distribution. Second, the model partitions mass into a detectable mobile phase and an undetectable, immobile phase. This two-phase transport model predicts two other features observed in the data: a decrease in the amount of detected tracer mass over the course of the experiment and the high initial velocity of the tracer plume. Because our model uses a heavy-tailed velocity distribution with a divergent second moment it is non-local and non-Fickian and able to reproduce aspects of the data that a local, Fickian model cannot. The model's successful prediction of the observed concentration profiles provides some of the first evidence of anomalous dispersion of bed load in a natural river.

  10. Performance of CASTORR HAW Cask Cold Trials for Loading, Transport and Storage of HAW canisters

    International Nuclear Information System (INIS)

    Wilmsmeier, Marco; Vossnacke, Andre

    2008-01-01

    On the basis of reprocessing contracts, concluded between the German Nuclear Utilities (GNUs) and the reprocessing companies in France (AREVA NC) and the UK (Nuclear Decommissioning Authority), GNS has the task to return the resulting residues to Germany. The high active waste (HAW) residuals from nuclear fuel reprocessing are vitrified and filled into steel cans, the HAW canisters. According to reprocessing contracts the equivalent number of HAW canisters to heavy metals delivered has to be returned to the country of origin and stored at an interim storage facility where applicable. The GNS' CASTOR R HAW casks are designed and licensed to fulfil the requirements for transport and long-term storage of HAW canisters. The new cask type CASTOR R HAW28M is capable of storing 28 HAW canisters with a maximum thermal power of 56 kW in total. Prior to the first active cask loading at a reprocessing facility it is required to demonstrate all important handling steps with the CASTOR R HAW28M cask according to a specific and approved sequence plan (MAP). These cold trials have to be carried out at the cask loading plant and at the reception area of an interim storage facility in Gorleben (TBL-G), witnessed by the licensing authorities and their independent experts. At transhipment stations GNS performs internal trials to demonstrate safe handling. A brand-new, empty CASTOR R HAW28M cask has been shipped from the GNS cask assembly facility in Muelheim to the TBL-G for cold trials. With this cask, GNS has to demonstrate the transhipment of casks at the Dannenberg transfer station from rail to road, transport to and reception at the TBL-G as well as incoming dose rate and contamination measurements and preparation for storage. After removal of all shock absorbers with a cask specific handling frame, tilting operation and assembly of the secondary lid with a pressure sensor, the helium leak tightness and 'Block-mass' tests have to be carried out as well. GNS long-term CASTOR R

  11. Transportation of 33 irradiated MTR fuel assemblies from FRM/Garching to Savannah River Site, USA, using a GNS transport cask and using a new loading device

    International Nuclear Information System (INIS)

    Dreesen, K.; Goetze, H.G.; Holst, L.; Gerstenberg, H.; Schreckenbach, K.

    2000-01-01

    According to the Department of Energy program of the return spent fuel from the foreign research reactors operators, 33 irradiated MTR box shaped fuel assemblies from the Technical University Munich were shipped to SRS/USA. The fuel assemblies were irradiated for typically 800 full days and, after a sufficient cooling time, loaded into a GNS 16 cask. The GNS 16 cask is a new transport cask for box shaped MTR fuel assemblies and TRIGA fuel assemblies and was used for the first time at the FRM Garching. The capacity of the cask is 33 box shaped MTR fuel assemblies. During the loading of the fuel assemblies, a newly developed loading device was used. The main components of the loading device are the transfer flask, the shielded loading lock, adapter plate and a mobile water tank. The loading device works mechanically with manpower. For the handling of the transfer flask, a crane with a capacity of 5 metric tons is necessary. During installation of the lid the mobile water pool is filled with demineralized water and the shielded loading passage is taken away. After that the lid is put on the cask. After drainage, the mobile water pool is disassembled, and the cask is dewatered. Finally leak tests of all seals are made. The achieved leakage rate was -5 Pa x I/s. The work in FRM was done between 03.02.99 and 12.02.99 including a dry run and leak test. (author)

  12. The design, fabrication and maintenance of semi-trailers employed in the highway transport of weight-concentrated radioactive loads

    Energy Technology Data Exchange (ETDEWEB)

    Huffman, D.S. [Allied-Signal Inc., Metropolis, IL (United States)

    1991-12-31

    Transportation of weight-concentrated radioactive loads by truck is an essential part of a safe and economical nuclear industry. This proposed standard presents guidance and performance criteria for the safe transport of these weight-concentrated radioactive loads. ANSI N14.30 will detail specific requirements for the design, fabrication, testing, in-service inspections, maintenance and certification of the semi-trailers to be employed in said service. Furthermore, guidelines for a quality assurance program are also enumerated. This standard would apply to any semi-trailer that may or may not be specifically designed to carry weight-concentrated loads. Equipment not suitable per the criteria established in the standard would be removed from service. The nature of the nuclear industry and the need for a positive public perception of the various processes and players, mandates that the highway transportation of weight-concentrated radioactive loads be standardized and made inherently safe. This proposed standard takes a giant step in that direction.

  13. Assessment of the transport routes of oversized and excessive loads in relation to the passage through roundabout

    Science.gov (United States)

    Petru, Jan; Dolezel, Jiri; Krivda, Vladislav

    2017-09-01

    In the past the excessive and oversized loads were realized on selected routes on roads that were adapted to ensure smooth passage of transport. Over the years, keeping the passages was abandoned and currently there are no earmarked routes which would be adapted for such type of transportation. The routes of excessive and oversized loads are currently planned to ensure passage of the vehicle through the critical points on the roads. Critical points are level and fly-over crossings of roads, bridges, toll gates, traffic signs and electrical and other lines. The article deals with the probability assessment of selected critical points of the route of the excessive load on the roads of 1st class, in relation to ensuring the passage through the roundabout. The bases for assessing the passage of the vehicle with excessive load through a roundabout are long-term results of video analyses of monitoring the movement of transports on similar intersections and determination of the theoretical probability model of vehicle movement at selected junctions. On the basis of a virtual simulation of the vehicle movement at crossroads and using MonteCarlo simulation method vehicles’ paths are analysed and the probability of exit of the vehicle outside the crossroad in given junctions is quantified.

  14. An inventory model of purchase quantity for fully-loaded vehicles with maximum trips in consecutive transport time

    Directory of Open Access Journals (Sweden)

    Chen Pоуu

    2013-01-01

    Full Text Available Products made overseas but sold in Taiwan are very common. Regarding the cross-border or interregional production and marketing of goods, inventory decision-makers often have to think about how to determine the amount of purchases per cycle, the number of transport vehicles, the working hours of each transport vehicle, and the delivery by ground or air transport to sales offices in order to minimize the total cost of the inventory in unit time. This model assumes that the amount of purchases for each order cycle should allow all rented vehicles to be fully loaded and the transport times to reach the upper limit within the time period. The main research findings of this study included the search for the optimal solution of the integer planning of the model and the results of sensitivity analysis.

  15. Inclined Weight-Loaded Walking at Different Speeds: Pelvis-Shoulder Coordination, Trunk Movements and Cost of Transport.

    Science.gov (United States)

    Rosa, Rodrigo Gomes da; Gomeñuka, Natalia Andrea; Oliveira, Henrique Bianchi de; Peyré-Tartaruga, Leonardo Alexandre

    2018-01-01

    Although studied at level surface, the trunk kinematics and pelvis-shoulder coordination of incline walking are unknown. The aim of this study was to evaluate the speed effects on pelvis-shoulder coordination and trunk movement and the cost of transport (C) during unloaded and loaded (25% of body mass) 15% incline walking. We collected 3-dimensional kinematic and oxygen consumption data from 10 physically active young men. The movements were analyzed in the sagittal plane (inclination and range of trunk motion) and the transverse plane (range of shoulder and pelvic girdle motion and phase difference). The rotational amplitude of the shoulder girdle decreased with load at all speeds, and it was lower at the highest speeds. The rotational amplitude of the pelvic girdle did not change with the different speeds. The phase difference was greater at optimal speed (3 km.hr -1 , at the lowest C) in the loaded and the unloaded conditions. The trunk inclination was greater with load and increased with speed, whereas the range of trunk motion was lower in the loaded condition and decreased with increasing speed. In conclusion, the load decreased the range of girdles and trunk motion, and the pelvis-shoulder coordination seemed to be critical for the incline walking performance.

  16. Detection system for location of fuel pebbles transported in pipes in a pebble-bed reactor based on vibration signal processing

    International Nuclear Information System (INIS)

    Liu, Hongbing; Du, Dong; Huang, An; Chang, Baohua; Han, Zandong; He, Ayada

    2016-01-01

    Highlights: • A detection system for locations of pebbles transported in pipes is introduced. • The detection system is based on vibration signal processing, which is original. • The characteristics of the vibration signals of the pipe are analyzed. • The experiment shows that the detection results are accurate. • The research provides an important basis for the design of the reactor. - Abstract: Pebble-bed high temperature gas-cooled reactors have many advantages such as inherent safety, high efficiency, etc., and have been considered as a candidate for Generation IV nuclear reactors. During the operation of the reactor, there are thousands of fuel pebbles transported in the pipes outside the core by gravity and helium flow. The pattern of the pipes which consist of straight and arc sections is very complex. When a fuel pebble is transported, it will constantly collide with the pipes, especially in the arc sections. The collisions will lead to the vibration of the pipes. This paper aims to provide a detection system for the location of fuel pebbles transported in pipes in a pebble-bed reactor based on vibration signal processing. Before the reactor is running, the system acquires the vibration signals of several key sections by sensors. Then the frequency characteristics of the signals are obtained by joint time–frequency analysis. When the reactor is running, the system detects the signals and processes them based on their frequency characteristics in real time. According to the results of the processing, the system can correctly judge whether the fuel pebble has passed through the section and records the time of the passing. The experiment validates the accuracy and reliability of the detection results. In this way, the operational condition of the reactor can be monitored so that the normal running of the reactor can be ensured. Additionally, the detection data are of great significance to the evaluation and optimization of the reactor performance

  17. Detection system for location of fuel pebbles transported in pipes in a pebble-bed reactor based on vibration signal processing

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Hongbing, E-mail: liuhb07@mails.tsinghua.edu.cn [Department of Mechanical Engineering, Tsinghua University, Beijing 100084 (China); Key Laboratory for Advanced Materials Processing Technology, Ministry of Education P. R. China, Beijing 100084 (China); Du, Dong, E-mail: dudong@tsinghua.edu.cn [Department of Mechanical Engineering, Tsinghua University, Beijing 100084 (China); Key Laboratory for Advanced Materials Processing Technology, Ministry of Education P. R. China, Beijing 100084 (China); Huang, An; Chang, Baohua; Han, Zandong [Department of Mechanical Engineering, Tsinghua University, Beijing 100084 (China); Key Laboratory for Advanced Materials Processing Technology, Ministry of Education P. R. China, Beijing 100084 (China); He, Ayada [Shanghai Electric Power Generation Group Shanghai Generator Works, Shanghai 200240 (China)

    2016-08-15

    Highlights: • A detection system for locations of pebbles transported in pipes is introduced. • The detection system is based on vibration signal processing, which is original. • The characteristics of the vibration signals of the pipe are analyzed. • The experiment shows that the detection results are accurate. • The research provides an important basis for the design of the reactor. - Abstract: Pebble-bed high temperature gas-cooled reactors have many advantages such as inherent safety, high efficiency, etc., and have been considered as a candidate for Generation IV nuclear reactors. During the operation of the reactor, there are thousands of fuel pebbles transported in the pipes outside the core by gravity and helium flow. The pattern of the pipes which consist of straight and arc sections is very complex. When a fuel pebble is transported, it will constantly collide with the pipes, especially in the arc sections. The collisions will lead to the vibration of the pipes. This paper aims to provide a detection system for the location of fuel pebbles transported in pipes in a pebble-bed reactor based on vibration signal processing. Before the reactor is running, the system acquires the vibration signals of several key sections by sensors. Then the frequency characteristics of the signals are obtained by joint time–frequency analysis. When the reactor is running, the system detects the signals and processes them based on their frequency characteristics in real time. According to the results of the processing, the system can correctly judge whether the fuel pebble has passed through the section and records the time of the passing. The experiment validates the accuracy and reliability of the detection results. In this way, the operational condition of the reactor can be monitored so that the normal running of the reactor can be ensured. Additionally, the detection data are of great significance to the evaluation and optimization of the reactor performance

  18. Characteristics of Loads of Cattle Stopping for Feed, Water and Rest during Long-Distance Transport in Canada

    Directory of Open Access Journals (Sweden)

    Hannah E. Flint

    2014-03-01

    Full Text Available This study is the first comprehensive examination of long-haul cattle being transported across Canada and off-loaded for feed, water and rest. A total of 129 truckloads were observed at one of two commercial rest stations near Thunder Bay, Ontario. Data collected included information regarding the truck driver, the trailer, the trip, the animals and animal handling. The majority of the loads stopping were feeder calves (60.94% while 21.09% were weaned calves, and the remaining 14.84% were market weight cattle. The truck loads surveyed were in transit for, on average, 28.2 ± 5.0 hours before stopping and cattle were rested for an average of 11.2 ± 2.8 hours. These data suggest that loads stopping at the rest station were adhering to the regulations stated in the Health of Animals Act, which outline a maximum of 48 hours in transit before a mandatory stop of at least 5 hours for feed, water and rest. There was a large amount of variability around how well recommendations, such as stocking density were followed. Further research is required to assess how well cattle are coping with long-distance transport under current regulations and industry practices.

  19. Structural analysis of deformations in the seal region of a radioactive material transport cask under thermal loadings

    International Nuclear Information System (INIS)

    Turula, P.; Wang, Z.

    1991-01-01

    In the design of casks for the transport of highly radioactive materials, a major concern is preventing leakage under both the normal conditions of transport and the hypothetical accident conditions specified in the federal regulations. The designs must accommodate various loadings, including thermal loadings. The latter are particularly difficult to withstand because thermal considerations require exceptional structural flexibility, while other design considerations require structural stiffness. To guarantee a design that will be leaktight, the designer needs to quantify and limit the range of possible movement between the cask body and the lid under all conditions. This paper first shows the deformations obtained from a simplified model of the basic configuration of a sample design under selected normal and hypothetical thermal loading conditions. The design is then modified and re-analyzed to evaluate the effectiveness of two configuration modifications intended to reduce relative movement at the closure interface between cask body and the lid. Comparisons of required bolting forces demonstrate that accommodating the thermal loadings must be a primary consideration in designing the cask. 5 refs., 6 figs., 1 tab

  20. Tolerance Limit for Trucks with Excess Load in Transport Regulation in Indonesia

    Directory of Open Access Journals (Sweden)

    Sigit Hadiwardoyo

    2012-05-01

    Full Text Available Reliability of a road is mandatory since damaged will impede the traffic. Destruction is caused by various factors; one of the most important factors is excess load. Overload may give the load of each axle of a vehicle exceeds the determined standard. This condition occurs in trucks exceeding the load limit. In designing the structure of a road based on the method of Directorate General of Highways Ministry of Public Works of the Republic of Indonesia, axle load calculated in equivalent-number, or known as equivalent axle load (EAL, of 8.16 tons of standard axle. Total equivalent-number over the service life is defined as cumulative equivalent standard axle load (CESA. Due to traffic volume exceeding the volume forecast or, in other words there is an excessive load of traffic, it will make CESA achieved faster than planned. This excessive load in Indonesia, however, has been  considered as a factor of environmental condition, so there is a need to introduce a correction factor for EAL as high as 20-25% in the process of designing flexible and rigid pavement so as to reduce early damage.

  1. An analysis of bedload and suspended load interactions

    Science.gov (United States)

    Recking, alain; Navratil, Oldrich

    2013-04-01

    Several approaches were used to develop suspension equations. It includes semi-theoretical equations based on the convection diffusion equation (Einstein 1950; Van Rijn 1984; Camenen and Larson 2008; Julien 2010), semi-empirical tools based on energy concept (Velikanov 1954; Bagnold 1966), empirical adjustments (Prosser and Rusttomji 2000). One essential characteristic of all these equations is that most of them were developed by considering continuity between bedload and suspended load, and that the partitioning between these two modes of transport evolves progressively with increasing shear stress, which is the case for fine bed materials. The use of these equations is thus likely to be welcome in estuaries or lowland sandy rivers, but may be questionable in gravel-bed rivers and headwater streams where the bed is usually structured vertically and fine sediments potentially contributing to suspension are stored under a poorly mobile surface armour comprising coarse sediments. Thus one question this work aimed to answer is does the presence of an armour at the bed surface influence suspended load? This was investigated through a large field data set comprising instantaneous measurements of both bedload and suspension. We also considered the river characteristics, distinguishing between lowland rivers, gravel bed rivers and headwater streams. The results showed that a correlation exist between bedload and suspension for lowland and gravel bed rivers. This suggests that in gravel bed rivers a large part of the suspended load is fed by subsurface material, and depends on the remobilization of the surface material. No correlation was observed for head water streams where the sediment production is more likely related to hillslope processes. These results were used with a bedload transport equation for proposing a method for suspended load estimate. The method is rough, but especially for gravel bed rivers, it predicts suspended load reasonably well when compared to

  2. Impaired phloem loading in zmsweet13a,b,c sucrose transporter triple knock-out mutants in Zea mays.

    Science.gov (United States)

    Bezrutczyk, Margaret; Hartwig, Thomas; Horschman, Marc; Char, Si Nian; Yang, Jinliang; Yang, Bing; Frommer, Wolf B; Sosso, Davide

    2018-04-01

    Crop yield depends on efficient allocation of sucrose from leaves to seeds. In Arabidopsis, phloem loading is mediated by a combination of SWEET sucrose effluxers and subsequent uptake by SUT1/SUC2 sucrose/H + symporters. ZmSUT1 is essential for carbon allocation in maize, but the relative contribution to apoplasmic phloem loading and retrieval of sucrose leaking from the translocation path is not known. Here we analysed the contribution of SWEETs to phloem loading in maize. We identified three leaf-expressed SWEET sucrose transporters as key components of apoplasmic phloem loading in Zea mays L. ZmSWEET13 paralogues (a, b, c) are among the most highly expressed genes in the leaf vasculature. Genome-edited triple knock-out mutants were severely stunted. Photosynthesis of mutants was impaired and leaves accumulated high levels of soluble sugars and starch. RNA-seq revealed profound transcriptional deregulation of genes associated with photosynthesis and carbohydrate metabolism. Genome-wide association study (GWAS) analyses may indicate that variability in ZmSWEET13s correlates with agronomical traits, especifically flowering time and leaf angle. This work provides support for cooperation of three ZmSWEET13s with ZmSUT1 in phloem loading in Z. mays. © 2018 The Authors. New Phytologist © 2018 New Phytologist Trust.

  3. Ascent structural wind loads for the National Space Transportation System (NSTS)

    Science.gov (United States)

    Smith, O. E.; Adelfang, S. I.; Brown, R. P.

    1988-01-01

    An aerospace vehicle must withstand the design ascent structural load or be within any flight constraint to safely reach orbit. For the NSTS an assessment for flight readiness is made for each mission. This assessment for ascent loads and performance parameters is stated in terms of launch probability derived from samples of Jimsphere wind profiles. For the day of launch operations an allowance is made for the ascent load variability due to the wind profile variability over a 3.5-hour period. This is the current time period required to obtain a Jimsphere measurement and perform a complete load simulation prior to launch time. The load variability is derived from a sample of 3.5-hour Jimsphere wind profile pairs. It is applied as a conditional percentile value given the wind load at 3.5 hours prior to launch time. Probability models are used for these analyses. Application of the univariate, bivariate and conditional forms of the extreme value (Gumbel) probability distribution to the analysis of extreme wind speeds, wind shears and vehicle loads is described.

  4. Changes in ADC Caused by Tensile Loading of Rabbit Achilles Tendon: Evidence for Water Transport

    Science.gov (United States)

    Han, S.; Gemmell, S. J.; Helmer, K. G.; Grigg, P.; Wellen, J. W.; Hoffman, A. H.; Sotak, C. H.

    2000-06-01

    Water diffusion measurements were performed on rabbit Achilles tendons during static tensile loading and tendons in an unloaded state. The apparent diffusion coefficient (ADC) was measured along two directions: parallel and perpendicular to the long axis of the tendon. Tendons were studied after being prepared in two ways: (a) after being stored frozen in phosphate-buffered saline (PBS) and (b) freshly isolated. Statistically significant directional anisotropy was observed in the ADC in all tendons. The ADC was significantly greater in the direction parallel to the long axis of the tendon than in the perpendicular direction. The anisotropy is attributed to the greater restrictions seen by the water molecules in the perpendicular direction and is consistent with the known geometry of the tendon. Storage in PBS caused tendons to swell. This increased the ADC measured along both directions and reduced the anisotropy. The existence of anisotropy in the ADC was not related to the orientation of the specimen in the magnet. The ADC increased along both directions following the application of a 5-N tensile load; the increase was greatest along the perpendicular axis of the tendon. In order to determine whether load-related changes in the ADC reflected changes in interfibrilar spacing, we used electron microscopy to measure load-related changes in fibril spacing. Load-related changes in fiber spacing could not account for the observed changes in the ADC. The increase in ADC caused by loading was attributed to the extrusion of tendon water into a bulk phase along the outside surface of the tendon. In PBS-stored samples, enough fluid was extruded that it could be visualized. The transient response of the ADC to a 5-N tensile load was also studied. The absolute ADC in both directions increased with loading and recovered to baseline upon unloading. The transient changes in ADC, for both loading and unloading, had a mean time constant of approximately 15 min. The magnitude of

  5. Modeling phosphate transport and removal in a compact bed filled with a mineral-based sorbent for domestic wastewater treatment.

    Science.gov (United States)

    Herrmann, Inga; Jourak, Amir; Gustafsson, Jon Petter; Hedström, Annelie; Lundström, T Staffan; Viklander, Maria

    2013-11-01

    Phosphorus filter units containing mineral-based sorbents with a high phosphate (PO4) binding capacity have been shown to be appropriate for removing PO4 in the treatment of domestic wastewater in on-site facilities. However, a better understanding of their PO4 removal mechanisms, and reactions that could lead to the formation of PO4 compounds, is required to evaluate the potential utility of candidate sorbents. Models based on data obtained from laboratory-scale experiments with columns of selected materials can be valuable for acquiring such understanding. Thus, in this study the transport and removal of PO4 in experiments with a laboratory-scale column filled with a commercial silicate-based sorbent were modeled, using the hydro-geochemical transport code PHREEQC. The resulting models, that incorporated the dissolution of calcite, kinetic constrains for the dissolution of calcium oxide (CaO) and wollastonite (CaSiO3), and the precipitation of amorphous tricalcium phosphate, Ca3(PO4)2, successfully simulated the removal of PO4 observed in the experiments. © 2013. Published by Elsevier B.V. All rights reserved.

  6. Tracking channel bed resiliency in forested mountain catchments using high temporal resolution channel bed movement

    Science.gov (United States)

    Martin, Sarah E.; Conklin, Martha H.

    2018-01-01

    This study uses continuous-recording load cell pressure sensors in four, high-elevation (1500-1800 m), Sierra Nevada headwater streams to collect high-temporal-resolution, bedload-movement data for investigating the channel bed movement patterns within these streams for water years 2012-2014. Data show an annual pattern where channel bed material in the thalweg starts to build up in early fall, peaks around peak snow melt, and scours back to baseline levels during hydrograph drawdown and base flow. This pattern is punctuated by disturbance and recovery of channel bed material associated with short-term storm events. A conceptual model, linking sediment sources at the channel margins to patterns of channel bed fill and scour in the thalweg, is proposed building on the results of Martin et al. (2014). The material in the thalweg represents a balance between sediment supply from the channel margins and sporadic, conveyor-belt-like downstream transport in the thalweg. The conceptual model highlights not only the importance of production and transport rates but also that seasonal connectedness between the margins and thalweg is a key sediment control, determining the accumulation rate of sediment stores at the margins and the redistribution of sediment from margins to thalweg that feeds the conveyor belt. Disturbance and recovery cycles are observed at multiple temporal scales; but long term, the channel beds are stable, suggesting that the beds act as short-term storage for sediment but are in equilibrium interannually. The feasibility of use for these sensors in forested mountain stream environments is tested. Despite a high failure rate (50%), load cell pressure sensors show potential for high-temporal-resolution bedload measurements, allowing for the collection of channel bed movement data to move beyond time-integrated change measurements - where many of the subtleties of bedload movement patterns may be missed - to continuous and/or real-time measurements. This

  7. Remote Loading of 64Cu2+ into Liposomes without the Use of Ion Transport Enhancers

    DEFF Research Database (Denmark)

    Henriksen, Jonas Rosager; Petersen, Anncatrine Luisa; Hansen, Anders Elias

    2015-01-01

    depleted, cationic, anionic, and zwitterionic lipid compositions. We demonstrate high in vivo stability of 64Cu-liposomes in a large canine model observing a blood circulation half-life of 24 h and show a tumor accumulation of 6% ID/g in FaDu xenograft mice using PET imaging. With this work......Due to low ion permeability of lipid bilayers, it has been and still is common practice to use transporter molecules such as ionophores or lipophilic chelators to increase transmembrane diffusion rates and loading efficiencies of radionuclides into liposomes. Here, we report a novel and very simple...... method for loading the positron emitter 64Cu2+ into liposomes, which is important for in vivo positron emission tomography (PET) imaging. By this approach, copper is added to liposomes entrapping a chelator, which causes spontaneous diffusion of copper across the lipid bilayer where it is trapped. Using...

  8. Application of the SWAT model to an AMD-affected river (Meca River, SW Spain). Estimation of transported pollutant load

    Science.gov (United States)

    Galván, L.; Olías, M.; Fernandez de Villarán, R.; Domingo Santos, J. M.; Nieto, J. M.; Sarmiento, A. M.; Cánovas, C. R.

    2009-10-01

    SummaryThe Meca River is highly contaminated by acid mine drainage coming from the Tharsis mining district, belonging to the Iberian Pyrite Belt. This river is regulated by the Sancho reservoir (58 hm 3), with a pH close to 4.2. In this work, the load transported by the Meca River to the Sancho reservoir has been assessed. Due to the lack of streamflow data, the hydrological behaviour of the Meca River basin has been simulated using the SWAT model. The model has been calibrated against registered daily inflows of the Sancho reservoir (1982-2000), excluding the hydrological years 2000/2001 and 2001/2002 that were kept for the validation. The results were satisfactory; the evaluation coefficients for monthly calibration were: r = 0.85 (Pearson's correlation coefficient), NSE = 0.83 (Nash-Sutcliffe coefficient) and DV = 1.08 (runoff volume deviation). The main uncertainty was the calibration during low water because of the poor accuracy in the measurement of the inputs to the reservoir in these conditions. Discharge and dissolved concentration relationships for different elements were obtained from hydrochemical samplings, which allowed us to estimate the element pollutant load transported to the reservoir: 418 ton/year of Al, 8024 ton/year of SO 4, 121 ton/year of Zn, etc. Based on these loads, concentrations in the reservoir were calculated for some elements. Apart from Mn and Sr, good adjustment between calculated and measured values was observed (±20% for Ca, Co, Li, Mg, Na, Ni, Zn and SO 4). Capsule: Hydrological model combined with water quality data show how pollution by AMD can generate huge loads of contaminants acidifying streams and reservoirs.

  9. Determination of the solid consumption in the transport of sands in sea beds with gold 198; Determinacion del gasto solido en el transporte de arenas en lechos marinos con oro 198

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez A, G

    1983-07-01

    The study of the movement of sediments in sea beds, is necessary when one plans to build a port. Among the techniques used for this studies, it is the radiotracer balance that gives an useful estimation of the quantity of sediment that it moves per day and by meter (perpendicular to the displacement). The main objectives of this work are: to) to present the characteristics of the obtaining of the used radiotracer, describing details those used safety measures, b) to describe the handling of the radiotracer and it radiological safety, during the transport and injection in the sea bottom, c) description of the detection way and the used equipment, d) to describe the information processing obtained in the field and finally, e) the estimate of the solid consumption and the determination of the direction and speed of displacement of those sediments in the sea bottom, in front of the Tabasco coast, to be used jointly with the information obtained by means of other techniques so that one can make a good planning of the operations of dredging during the construction and later on the maintenance of the Dos Bocas marine terminal. The first step is to obtain the radiotracer that in this case was sand of uniform grain metric, marked superficially with Gold-198. The second step is to transport the sand to the place of interest, to place it in the injection equipment and to deposit it in the sea bottom. The third step is to detect the radiotracer in the sea bed, from a craft that drags a sled, which takes mounted a scintillation detector of sodium iodide activated with thallium NaI(Tl) (probe). The fourth step is to process the field information and to obtain the corresponding results. (Author)

  10. Analysis of offshore steel jacket during load-out and transport

    Digital Repository Service at National Institute of Oceanography (India)

    Mandal, S.; Chettiar, C.G.

    In transporting large offshore structures on barges to the installation sites, the structure and seafastenings will be experiencing very high stresses due to rough sea and severe wind conditions This is more critical in cases where the installation...

  11. Variability of Bed Drag on Cohesive Beds under Wave Action

    Directory of Open Access Journals (Sweden)

    Ilgar Safak

    2016-04-01

    Full Text Available Drag force at the bed acting on water flow is a major control on water circulation and sediment transport. Bed drag has been thoroughly studied in sandy waters, but less so in muddy coastal waters. The variation of bed drag on a muddy shelf is investigated here using field observations of currents, waves, and sediment concentration collected during moderate wind and wave events. To estimate bottom shear stress and the bed drag coefficient, an indirect empirical method of logarithmic fitting to current velocity profiles (log-law, a bottom boundary layer model for combined wave-current flow, and a direct method that uses turbulent fluctuations of velocity are used. The overestimation by the log-law is significantly reduced by taking turbulence suppression due to sediment-induced stratification into account. The best agreement between the model and the direct estimates is obtained by using a hydraulic roughness of 10 - 4 m in the model. Direct estimate of bed drag on the muddy bed is found to have a decreasing trend with increasing current speed, and is estimated to be around 0.0025 in conditions where wave-induced flow is relatively weak. Bed drag shows an increase (up to fourfold with increasing wave energy. These findings can be used to test the bed drag parameterizations in hydrodynamic and sediment transport models and the skills of these models in predicting flows in muddy environments.

  12. Variability of bed drag on cohesive beds under wave action

    Science.gov (United States)

    Safak, Ilgar

    2016-01-01

    Drag force at the bed acting on water flow is a major control on water circulation and sediment transport. Bed drag has been thoroughly studied in sandy waters, but less so in muddy coastal waters. The variation of bed drag on a muddy shelf is investigated here using field observations of currents, waves, and sediment concentration collected during moderate wind and wave events. To estimate bottom shear stress and the bed drag coefficient, an indirect empirical method of logarithmic fitting to current velocity profiles (log-law), a bottom boundary layer model for combined wave-current flow, and a direct method that uses turbulent fluctuations of velocity are used. The overestimation by the log-law is significantly reduced by taking turbulence suppression due to sediment-induced stratification into account. The best agreement between the model and the direct estimates is obtained by using a hydraulic roughness of 10 -4">−4 m in the model. Direct estimate of bed drag on the muddy bed is found to have a decreasing trend with increasing current speed, and is estimated to be around 0.0025 in conditions where wave-induced flow is relatively weak. Bed drag shows an increase (up to fourfold) with increasing wave energy. These findings can be used to test the bed drag parameterizations in hydrodynamic and sediment transport models and the skills of these models in predicting flows in muddy environments.

  13. Problems of increased transport load as a result of implementation of projects of high-rise constructions

    Science.gov (United States)

    Provotorov, Ivan; Gasilov, Valentin; Anisimova, Nadezhda

    2018-03-01

    The structure of problems of high-rise construction us suggested, which includes the impact on environment, design solutions, transportation problems, financial costs for construction and operation, and others. Positive and negative aspects of high-rise construction are considered. One of the basic problems of high-rise construction is the problem of increased transport load. Construction of the subway on the basis of the concession mechanism, with the use of unmanned control of rolling stock is proposed as the most expedient solution. An evaluation of the effectiveness of this project is presented, it shows quite high performance indicators for a private investor. Main problems that the project implementation may face in conditions of lack of scientific and methodological support are outlined.

  14. The role of water management on the oxygen transport resistance in polymer electrolyte fuel cell with ultra-low precious metal loading

    Science.gov (United States)

    Srouji, A. K.; Zheng, L. J.; Dross, R.; Aaron, D.; Mench, M. M.

    2017-10-01

    Limiting current measurements are used to evaluate oxygen transport resistance in the catalyst layer of a polymer electrolyte fuel cell (PEFC). The pressure independent oxygen transport resistance in the electrode is quantified for two cell architectures and two cathode Pt loadings (0.4 and 0.07 mgPt.cm-2). The compounded effect of the flow field and Pt loading is used to shed light on the nature of the observed transport resistance, especially its response to fundamentally different flow fields, which is shown to directly or indirectly scale with Pt loading in the open literature. By varying gas pressure and using low oxygen concentrations, the total oxygen transport resistance is divided into intermolecular gas diffusion (a pressure-dependent component) and a pressure independent component, which can be attributed to Knudsen diffusion or dissolution film resistance. The pressure-independent oxygen transport resistance in the catalyst layer varies between 13.3 and 34.4 s/m. It is shown that the pressure independent oxygen transport resistance increases with reduced Pt loading, but that effect is greatly exacerbated by using conventional channel/lands. The results indicate that open metallic element architecture improves the oxygen transport resistance in ultra-low Pt loading electrodes, likely due to enhanced water management at the catalyst layer.

  15. Impact of increasing freight loads on rail substructure from fracking sand transportation.

    Science.gov (United States)

    2014-03-01

    In this report the effect of surface infiltration of frac sand and heavy axle loads (HALs) were studied for their impact on the ballast layer. : Different combinations of ballast and fracking sand were constructed to observe long term trends of defor...

  16. Fluidized Bed Gasification as a Mature And Reliable Technology for the Production of Bio-Syngas and Applied in the Production of Liquid Transportation Fuels—A Review

    Directory of Open Access Journals (Sweden)

    Adrian H.M. Verkooijen

    2011-03-01

    Full Text Available Biomass is one of the renewable and potentially sustainable energy sources and has many possible applications varying from heat generation to the production of advanced secondary energy carriers. The latter option would allow mobile services like the transportation sector to reduce its dependency on the fossil fuel supply. This article reviews the state-of-the-art of the fluidization technology applied for the gasification of biomass aimed at the production of gas for subsequent synthesis of the liquid energy carriers via, e.g., the Fischer-Tropsch process. It discusses the advantages of the gasification technology over combustion, considers the size of the conversion plant in view of the local biomass availability, assesses the pros and cons of different gasifier types in view of the application of the product gas. Subsequently the article focuses on the fluidized bed technology to discuss the main process parameters and their influence on the product composition and the operability of the gasifier. Finally a synthesis process (FT is introduced shortly to illustrate the necessary gas cleaning steps in view of the purity requirements for the FT feed gas.

  17. Ratchetting behavior of primary heat transport (PHT) piping material SA-333 carbon steel subjected to cyclic loads at room temperature

    International Nuclear Information System (INIS)

    Kulkarni, S.; Desai, Y.M.; Kant, T.; Reddy, G.R.; Gupta, C.; Chakravarthy, J.K.

    2004-01-01

    Ratchetting behavior of SA-333 Gr. 6 carbon steel used as primary heat transport (PHT) piping material has been investigated with three constitutive models proposed by Armstrong-Frederick, Chaboche and Ohno-Wang involving different hardening rules. Performance of the above mentioned models have been evaluated for a broad set of uniaxial and biaxial loading histories. The uniaxial ratchetting simulations have been performed for a range of stress ratios (R) by imposing different stress amplitudes and mean stress conditions. Numerical simulations indicated significant ratchetting and opening of hysteresis loop for negative stress ratio with constant mean stress. Application of cyclic stress without mean stress (R = -1.0) has been observed to produce negligible ratchet-strain accumulation in the material. Simulation under the biaxial stress condition was based on modeling of an internally pressurized thin walled pipe subjected to cyclic bending load. Numerical results have been validated with the experiments as per simulation conditions. All three models have been found to predict the observed accumulation of circumferential strain with increasing number of cycles. However, the Armstrong Frederick (A-F) model was found to be inadequate in simulating the ratchetting response for both uniaxial as well as biaxial loading cases. The A-F model actually over-predicted the ratchetting strain in comparison with the experimental strain values. On the other hand, results obtained with the Chaboche and the Ohno-Wang models for both the uniaxial as well as biaxial loading histories have been observed to closely simulate the experimental results. The Ohno-Wang model resulted in better simulation for the presents sets of experimental results in comparison with the Chaboche model. It can be concluded that the Ohno-Wang model suited well compared to the Chaboche model for above sets of uniaxial and biaxial loading histories. (authors)

  18. Experimental investigations on a fuel element transportation vessel for analysis of mechanical loads

    International Nuclear Information System (INIS)

    Diersch, R.; Ulrich, N.; Huggenberg, R.; Janberg, K.; Ettemeyer, A.

    1995-01-01

    During approval of fuel element transportation vessels extensive proofs have to be made to qualify the theoretical calculations. In order to get maximum information about the behaviour of the components of the vessels and the real boundary conditions holographic measuring techniques are used. The application of holography on the experimental analysis of a fuel element transportation vessel is shown on a THTR-CASTOR-container. As an example, the deformation of a lifting lug is analysed and the flexible bending of the vessel cap is measured. The experimental results are compared with analytical calculation results. (orig.)

  19. Experimental study on evolution of bed structures of natural mountain rivers

    Directory of Open Access Journals (Sweden)

    Huai-xiang Liu

    2011-06-01

    Full Text Available Bed structures in many mountain rivers provide additional resistance to the flow. A field experiment was conducted on debris flow deposits in the valley of the Jiangjiagou Ravine, a tributary of the Yangtze River in southwestern China, to study the evolution and distribution of bed structures and their relationship with environmental conditions. Water and sediment from the Jiangjiagou main stream were diverted into the experimental channel. Several hydrological schemes were adopted to scour the channel until equilibrium was reached. During this process the evolutions of bed structures and channel configuration were investigated. The results indicate that stronger bed structures mean greater stream power consumption, greater resistance, and greater slope in a certain section when rivers are in dynamic equilibrium. Thus, to some extent the longitudinal profiles of channels can be determined by the distribution of bed structures. In natural cases, the strength and evolution of bed structures are under the influence of environmental conditions such as discharge and bed-load transportation rate. That is, given the same conditions, the same bed structure distribution and longitudinal profile can be predicted.

  20. Loading density and welfare of goat kids during long distance road transport

    NARCIS (Netherlands)

    Hindle, V.A.; Reimert, H.G.M.; Werf, van der J.T.N.; Lambooij, E.

    2013-01-01

    Many goat kids (Capra aegagrus hircus) are transported live from The Netherlands for slaughter in France or Spain. Current standards indicate that goats (<35 kg) should have sufficient space at 0.2–0.30 m2 per animal (approximately 5 goats per m2). Research was devised to assess behaviour and

  1. Role of the convergence zone over West Africa in controlling Saharan mineral dust load and transport in the boreal summer

    Directory of Open Access Journals (Sweden)

    Owen M. Doherty

    2014-07-01

    Full Text Available During summer, large amounts of mineral dust are emitted and transported from North Africa over the tropical North Atlantic towards the Caribbean with the exact quantity varying greatly from year to year. Much effort has been made to explain the variability of summer season mineral dust load, for example, by relating dust variability to teleconnection indices such as ENSO and the NAO. However, only weak relationships between such climate indices and the abundance of mineral dust have been found. In this work, we demonstrate the role of the near-surface convergence zone over West Africa in controlling dust load and transport of mineral dust. We apply the ‘Center of Action’ approach to obtain indices that quantify the movement and strength of the convergence zone using NCEP/NCAR Reanalysis data. The latitudinal position of the convergence zone is significantly correlated with the quantity of mineral dust at Barbados over the period 1965–2003 (r=−0.47. A southward displacement of the convergence zone is associated with both increased near-surface flow and decreased precipitation over the dust source regions of the southern Saharan desert, Sahel and Lake Chad. This in turn reduces soil moisture and vegetation, furthering the potential for dust emission. In contrast, the intensity of the convergence zone is not correlated with dust concentration at Barbados. We conclude that the coupling of changes in near-surface winds with changes in precipitation in source regions driven by a southward movement of the convergence zone most directly influence dust load at Barbados and over the tropical North Atlantic during summer.

  2. Year-round variations in the fluvial transport load of particulate 137Cs in a forested catchment affected by the Fukushima Daiichi Nuclear Power Plant accident

    International Nuclear Information System (INIS)

    Takeshi Matsunaga; Takahiro Nakanishi; Mariko Atarashi-Andoh; Erina Takeuchi; Kotomi Muto; Katsunori Tsuduki; Syusaku Nishimura; Jun Koarashi; Shigeyoshi Otosaka; Tsutomu Sato

    2016-01-01

    Particulate 137 Cs was collected from stream water for 2 years to assess the long-term trend of 137 Cs discharge from a forest after the Fukushima Nuclear Power Plant accident. A seasonal increase in the fluvial transport load of particulate 137 Cs in suspended solids (SS) was observed in July-October when rainfall was abundant. The 137 Cs load was controlled by the SS load. This control was attributed to cesium affinity for phyllosilicate clay minerals as verified by the low extractability of particulate 137 Cs. These findings indicate the fluvial particulate 137 Cs load is significantly related to the climate and geomorphological features of Japan. (author)

  3. Sampling surface and subsurface particle-size distributions in wadable gravel-and cobble-bed streams for analyses in sediment transport, hydraulics, and streambed monitoring

    Science.gov (United States)

    Kristin Bunte; Steven R. Abt

    2001-01-01

    This document provides guidance for sampling surface and subsurface sediment from wadable gravel-and cobble-bed streams. After a short introduction to streams types and classifications in gravel-bed rivers, the document explains the field and laboratory measurement of particle sizes and the statistical analysis of particle-size distributions. Analysis of particle...

  4. Linear and nonlinear instabilities of a granular bed: determination of the scales of ripples and dunes in rivers

    OpenAIRE

    Franklin, Erick de Moraes

    2016-01-01

    Granular media are frequently found in nature and in industry and their transport by a fluid flow is of great importance to human activities. One case of particular interest is the transport of sand in open-channel and river flows. In many instances, the shear stresses exerted by the fluid flow are bounded to certain limits and some grains are entrained as bed-load: a mobile layer which stays in contact with the fixed part of the granular bed. Under these conditions, an initially flat granula...

  5. Effect of algae on flocculation of suspended bed sediments in a large shallow lake. Consequences for ecology and sediment transport processes

    Science.gov (United States)

    de Lucas Pardo, Miguel Angel; Sarpe, Dirk; Winterwerp, Johan Christian

    2015-06-01

    Lake Markermeer, a large shallow lake in The Netherlands, suffers from turbidity and ecology problems. As part of a study aiming to mitigate these problems, we study flocculation processes in the lake; in particular, the possible mutual flocculation between algae and re-suspended bed sediments. We show that sediment re-suspended from the bed of the lake can flocculate, forming flocs for which size is a function of the turbulence level in the water column. Moreover, we also demonstrate that algae and re-suspended bed sediments can mutually flocculate, yielding organic-inorganic aggregates. These aggregates have different features to those of their individual components, some of which have been measured and characterized in this paper. Furthermore, the characteristics of the resulting organic-inorganic flocs are strongly influenced by the type of algae in the aggregate. We found that, in the case of flocs consisting of bed sediments and filamentous algae, flocculation yields smaller flocs than for bed sediments only, resulting in an increased turbidity in the water column. In the case of flocs consisting of bed sediments and colonial algae, flocs grow faster and become larger than bed sediment flocs, which may result in the depletion of most colonies from the water column.

  6. Modeling transport of nutrients & sediment loads into Lake Tahoe under climate change

    Science.gov (United States)

    Riverson, John; Coats, Robert; Costa-Cabral, Mariza; Dettinger, Mike; Reuter, John; Sahoo, Goloka; Schladow, Geoffrey

    2013-01-01

    The outputs from two General Circulation Models (GCMs) with two emissions scenarios were downscaled and bias-corrected to develop regional climate change projections for the Tahoe Basin. For one model—the Geophysical Fluid Dynamics Laboratory or GFDL model—the daily model results were used to drive a distributed hydrologic model. The watershed model used an energy balance approach for computing evapotranspiration and snowpack dynamics so that the processes remain a function of the climate change projections. For this study, all other aspects of the model (i.e. land use distribution, routing configuration, and parameterization) were held constant to isolate impacts of climate change projections. The results indicate that (1) precipitation falling as rain rather than snow will increase, starting at the current mean snowline, and moving towards higher elevations over time; (2) annual accumulated snowpack will be reduced; (3) snowpack accumulation will start later; and (4) snowmelt will start earlier in the year. Certain changes were masked (or counter-balanced) when summarized as basin-wide averages; however, spatial evaluation added notable resolution. While rainfall runoff increased at higher elevations, a drop in total precipitation volume decreased runoff and fine sediment load from the lower elevation meadow areas and also decreased baseflow and nitrogen loads basin-wide. This finding also highlights the important role that the meadow areas could play as high-flow buffers under climatic change. Because the watershed model accounts for elevation change and variable meteorological patterns, it provided a robust platform for evaluating the impacts of projected climate change on hydrology and water quality.

  7. Simplified methods for impact loads of solid-walled transportation packagings for radioactive materials

    International Nuclear Information System (INIS)

    Teper, W.W.; Sauve, R.G.

    1989-01-01

    Transportation packagings for radioactive materials must withstand severe impact conditions without loss of integrity and without excessive permanent distortions in the seal regions. The compliance with the requirements may be shown either through extensive testing, elastic- plastic impact analysis or a combination of both. Elastic- plastic finite element analysis, although less costly than testing, is usually expensive and time consuming. This paper presents simplified methods for determining the impact force for the following impact cases of solid walled casks: impact on a pin, impact on an edge, and impact on a corner. The results of the simplified methods are in good agreement with the results of elastic-plastic finite element analysis. It is shown that in each case almost the entire impact energy is dissipated by the plastic deformation of the material in the impact zone

  8. 49 CFR 236.706 - Bed, locking.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Bed, locking. 236.706 Section 236.706 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION, DEPARTMENT OF TRANSPORTATION RULES, STANDARDS, AND INSTRUCTIONS GOVERNING THE INSTALLATION, INSPECTION...

  9. Anomalous mass transport in Au/304 stainless steel powder under shock loading

    Energy Technology Data Exchange (ETDEWEB)

    Staudhammer, Karl P.

    2004-01-01

    Dynamic deformation experiments on gold plated 304L stainless steel powders were undertaken using a axial symmetrical implosion geometry. These experiments utilized pressures of 0.08 to 1.0 Mbar and contained a symmetric radial melt region along the central axis of the sample holder. To understand the role of deformation in a porous material, the pressure, and temperature as well as the deformation heat and associated defects must be accounted for. Using a strain controllable shock loading design it was possible to separate and control independently strain and pressure. Thus enabling the ability to control the added heat from the deformation process undergoing compaction/consolidation of the powder. When the added heat of consolidation deformation exceeds the melt temperature of the 304 powders, a melt zone results that can consume large regions of the compact. It is within these regions that very high diffusion of gold into the powder occurs. These anomalous increases have been observed via optical microscopy, scanning electron microscopy and EDAX measurements. Values exceeding 1200 m/sec have been measured and correlated to the powder sizes, size distribution and packing density, concomitant with sample container strains ranging from 2.0% to 26%.

  10. Modelling the effect of suspended load transport and tidal asymmetry on the equilibrium tidal sand wave height

    NARCIS (Netherlands)

    van Gerwen, W.; Borsje, Bastiaan Wijnand; Damveld, Johan Hendrik; Hulscher, Suzanne J.M.H.

    2018-01-01

    Tidal sand waves are rhythmic bed forms found in shallow sandy coastal seas, reaching heights up to ten meters and migration rates of several meters per year. Because of their dynamic behaviour, unravelling the physical processes behind the growth of these bed forms is of particular interest to

  11. Safety Analysis of 'Older/Aged' Handling and Transportation Equipment for Heavy Loads, Radioactive Waste and Materials in Accordance with German Nuclear Standards KTA 3902, 3903 and 3905

    International Nuclear Information System (INIS)

    Macias, P.; Prucker, E.; Stang, W.

    2006-01-01

    The purpose of this paper is to present a general safety analysis of important handling and transportation processes and their related equipment ('load chains' consisting of cranes, load-bearing equipment and load-attaching points). This project was arranged by the responsible Bavarian ministry for environment, health and consumer protection (StMUGV) in agreement with the power plant operators of all Bavarian nuclear power plants to work out potential safety improvements. The range of the equipment (e.g. reactor building, crane, refuelling machine, load-bearing equipment and load-attaching points) covers the handling and transportation of fuel elements (e. g. with fuel flasks), heavy loads (e.g. reactor pressure vessel closure head, shielding slabs) and radioactive materials and waste (e.g. waste flasks, control elements, fuel channels, structure elements). The handling equipment was subjected to a general safety analysis taking into account the ageing of the equipment and the progress of standards. Compliance with the current valid requirements of the state of science and technology as required by German Atomic Act and particularly of the nuclear safety KTA-standards (3902, 3903 and 3905) was examined. The higher protection aims 'safe handling and transportation of heavy loads and safe handling of radioactive materials and waste' of the whole analysis are to avoid a criticality accident, the release of radioactivity and inadmissible effects on important technical equipment and buildings. The scope of the analysis was to check whether these protection aims were fulfilled for all important technical handling and transportation processes. In particularly the design and manufacturing of the components and the regulations of the handling itself were examined. (authors)

  12. Resuspension created by bedload transport of macroalgae

    DEFF Research Database (Denmark)

    Canal Vergés, Paula; Kristensen, Erik; Flindt, Mogens

    2009-01-01

    surface sediment while drifting as bed load. To improve the understanding of this ballistic effect of moving plants on the sediment surface, controlled annular flume experiments were performed. Plant transport was measured together with turbidity and suspended particulate matter during increasing water......Earlier studies have quantified that plant bound transport in shallow lagoons and estuaries may periodically be the dominating nutrient transport form. In some of these field studies turbidity increased when plant transport increased. The hypothesis in this study is therefore that macroalgae erode...

  13. Performance of CASTOR{sup R} HAW Cask Cold Trials for Loading, Transport and Storage of HAW canisters

    Energy Technology Data Exchange (ETDEWEB)

    Wilmsmeier, Marco; Vossnacke, Andre [GNS Gesellschaft fuer Nuklear-Service mbH, Hollestrasse 7A, D-45127 Essen (Germany)

    2008-07-01

    On the basis of reprocessing contracts, concluded between the German Nuclear Utilities (GNUs) and the reprocessing companies in France (AREVA NC) and the UK (Nuclear Decommissioning Authority), GNS has the task to return the resulting residues to Germany. The high active waste (HAW) residuals from nuclear fuel reprocessing are vitrified and filled into steel cans, the HAW canisters. According to reprocessing contracts the equivalent number of HAW canisters to heavy metals delivered has to be returned to the country of origin and stored at an interim storage facility where applicable. The GNS' CASTOR{sup R} HAW casks are designed and licensed to fulfil the requirements for transport and long-term storage of HAW canisters. The new cask type CASTOR{sup R} HAW28M is capable of storing 28 HAW canisters with a maximum thermal power of 56 kW in total. Prior to the first active cask loading at a reprocessing facility it is required to demonstrate all important handling steps with the CASTOR{sup R} HAW28M cask according to a specific and approved sequence plan (MAP). These cold trials have to be carried out at the cask loading plant and at the reception area of an interim storage facility in Gorleben (TBL-G), witnessed by the licensing authorities and their independent experts. At transhipment stations GNS performs internal trials to demonstrate safe handling. A brand-new, empty CASTOR{sup R} HAW28M cask has been shipped from the GNS cask assembly facility in Muelheim to the TBL-G for cold trials. With this cask, GNS has to demonstrate the transhipment of casks at the Dannenberg transfer station from rail to road, transport to and reception at the TBL-G as well as incoming dose rate and contamination measurements and preparation for storage. After removal of all shock absorbers with a cask specific handling frame, tilting operation and assembly of the secondary lid with a pressure sensor, the helium leak tightness and 'Block-mass' tests have to be carried out

  14. Experiments in a high-amplitude Kinoshita meandering channel: 2. Implications of bend orientation on bed morphodynamics

    Science.gov (United States)

    Abad, Jorge D.; Garcia, Marcelo H.

    2009-02-01

    Experiments carried out under flat smooth bed condition in a periodic, asymmetric, Kinoshita meandering channel showed that bend skewness controls the three-dimensional mean flow (e.g., primary and secondary flow) and turbulence structure (e.g., location of shear layers and turbulent shear stresses). In this paper, similar hydraulic conditions are used to perform movable-bed experiments with uniform sediment size in order to study the effect of bend orientation on bed morphodynamics. Two main differences between the upstream- and downstream-skewed meander configurations are found: (1) for the case of bends oriented upstream valley, the bed forms are produced just upstream of the bend apex, whereas for the case of bends oriented downstream valley they are observed around the upstream inflection point, and (2) the downstream-skewed condition produces the deepest scour region, which is located downstream of the bend apex. A comparison with observations at two bends on the Wabash River, Illinois, shows some remarkable similarities with the bed morphology observed in the Kinoshita channel. Further analysis of the bed form celerity, bed load transport during evolution, and superimposition of migrating bed forms and their implications on bend migration are presented.

  15. The environment of nature reserves under anthropogenic load: air transport of pollution to the North of European Russia

    Science.gov (United States)

    Vinogradova, A. A.; Ivanova, Yu. A.; Veremeychik, A. O.

    2012-04-01

    Nature reserves are created to keep in their original states natural environment, flora and fauna of various ecological systems, territories, climatic zones, etc. Now natural objects everywhere exist under anthropogenic loading from man-made activities. It is impossible to avoid atmospheric or river transport of pollution to the environment of reserved territories. The main idea of the work is to analyze atmospheric transport of anthropogenic metals (Ni, Cu, Pb, Fe, Al), as well as of soot (black carbon - BC) from Russian large industrial areas (source-regions) to the territories of nature reserves at the North of European Russia - the Kostomukshsky reserve (KR) in Karelia (64.57°N, 30.67°E) and the Nenetzky reserve (NR) at the Pechora River mouth (68,5°N, 53,5°E). The basic data for these 2 points were back trajectories of air mass transport calculated for every day of January, April, July, and October during 10 years from 2001 to 2010. We used NCEP/NCAR Reanalysis Data Files with HYSPLIT 4 model and two approaches for analyzing the trajectories. The main source-regions were chosen for each reserve. The annual source emissions for the last decade are generalized from the data published by Roshydromet of Russia (http://www.nii-atmosphere.ru/files/PUBL/Eg_2008.doc). The deposition velocity was a sum of dry and wet components. The equal values of deposition velocities onto the surface were assumed for all impurities because they are mainly on submicron aerosol particles under atmospheric transport for a long distance. The seasonal and spatial variations of averaged deposition velocity were accounted in accordance with surface properties and precipitation regimes. As a result, the maximal air concentrations of aerosol pollutants are observed in cold seasons, whereas the maximal fluxes onto the surface occur in warm period. Thus, it's possible that the cleanest air does not indicate the same surface. Fe and Al are the crust (dust or soil) elements. Thus, their main

  16. Effect of algae on flocculation of suspended bed sediments in a large shallow lake. Consequences for ecology and sediment transport processes

    NARCIS (Netherlands)

    de Lucas Pardo, MiguelAngel; Sarpe, Dirk; Winterwerp, JohanChristian

    2015-01-01

    Lake Markermeer, a large shallow lake in The Netherlands, suffers from turbidity and ecology problems. As part of a study aiming to mitigate these problems, we study flocculation processes in the lake; in particular, the possible mutual flocculation between algae and re-suspended bed sediments. We

  17. Development of Yam Dioscorin-Loaded Nanoparticles for Paracellular Transport Across Human Intestinal Caco-2 Cell Monolayers.

    Science.gov (United States)

    Hsieh, Hung-Ling; Lee, Chia-Hung; Lin, Kuo-Chih

    2018-02-07

    Dioscorins, the major storage proteins of yam tubers, exert immunomodulatory activities. To improve oral bioavailability of dioscorins in the intestine, recombinant dioscorin (rDioscorin) was coated with N,N,N-trimethyl chitosan (TMC) and tripolyphosphate (TPP), resulting in the formation of TMC-rDio-TPP nanoparticles (NPs). The loading capacity and entrapment efficiency of rDioscorin in the NPs were 26 ± 0.7% and 61 ± 1.4%, respectively. The NPs demonstrated a substantial release profile in the pH environment of the jejunum. The rDioscorin released from the NPs stimulated proliferation and phagocytosis of the macrophage RAW264.7 and activated the gene expression of IL-1β and IL-6. Incubation of the NPs in the Caco-2 cell monolayer led to a 5.2-fold increase of P app compared with rDioscorin alone, suggesting that rDioscorin, with the assistance of TMC, can be promptly transported across the intestinal epithelia. These results demonstrate that the TMC-rDio-TPP NPs can be utilized for elucidating the immunopharmacological effects of dioscorins through oral delivery.

  18. Regulation of unbalanced electromagnetic moment in mutual loading systems of electric machines of traction rolling stock and multiple unit of mainline and industrial transport

    Directory of Open Access Journals (Sweden)

    A. M. Afanasov

    2014-12-01

    Full Text Available Purpose. The research data are aimed to identify the regulatory principles of unbalanced electromagnetic moment of mutually loaded electric machines of traction rolling stock and multiple unit of main and industrial transport. The purpose of this study is energy efficiency increase of the testing of traction electric machines of direct and pulse current using the improvement methods of their mutual loading, including the principles of automatic regulation of mutual loading system. Methodology. The general theoretical provisions and principles of system approach to the theoretical electric engineering, the theory of electric machines and theoretical mechanics are the methodological basis of this research. The known methods of analysis of electromagnetic and electromechanical processes in electrical machines of direct and pulse current are used in the study. Methods analysis of loading modes regulation of traction electric machines was conducted using the generalized scheme of mutual loading. It is universal for all known methods to cover the losses of idling using the electric power. Findings. The general management principles of mutual loading modes of the traction electric machines of direct and pulse current by regulating their unbalanced electric magnetic moment were developed. Regulatory options of unbalanced electromagnetic moment are examined by changing the difference of the magnetic fluxes of mutually loaded electric machines, the current difference of electric machines anchors, the difference of the angular velocities of electric machines shafts. Originality. It was obtained the scientific basis development to improve the energy efficiency test methods of traction electric machines of direct and pulse current. The management principles of mutual loading modes of traction electric machines were formulated. For the first time it is introduced the concept and developed the principles of regulation of unbalanced electromagnetic moment in

  19. Positive train control test bed interoperability upgrades.

    Science.gov (United States)

    2013-02-01

    Transportation Technology Center, Inc. (TTCI) upgraded the Positive Train Control (PTC) Test Bed to support additional PTC testing configurations under Federal Railroad Administration (FRA) Task Order 270. The scope of work provided additional PTC Co...

  20. Environmental assessment for DOE permission for the off-loading and transportation of commercial low-level radioactive waste across the Savannah River Site

    International Nuclear Information System (INIS)

    1997-10-01

    The Department of Energy (DOE) prepared this Environmental Assessment (EA) to assess the potential environmental impacts associated with DOE allowing Chem-Nuclear Systems, L.L.C. (CNS) to off-load and transport low-level radioactive waste (LLW) packages across the Savannah River Site (SRS), located near Aiken, South Carolina, to the nearby CNS facility. The proposed action entails DOE granting permission to CNS to use SRS for landing shipping barges at the existing SRS boat ramp and off-loading trailered LLW packages for transportation across SRS to the CNS facility. Project activities would include modification of the SRS boat ramp on the Savannah River, as needed for off-loading activities, and construction of a bridge across Lower Three Runs. The proposed action also encompasses any similar future off-loading and transportation activities for LLW en route to the CNS facility. The National Environmental Policy Act requires the assessment of environmental consequences of Federal actions that may affect the quality of the human environment. Based on the potential for impacts described herein, DOE will either publish a Finding of No Significant Impact or prepare an Environmental Impact Statement (EIS)

  1. Optimization of process variables of zanamivir-loaded solid lipid nanoparticles and the prediction of their cellular transport in Caco-2 cell model.

    Science.gov (United States)

    Shi, Li-Li; Cao, Yue; Zhu, Xiao-Yin; Cui, Jing-Hao; Cao, Qing-Ri

    2015-01-15

    The aim of this study was to optimize the process variables of zanamivir-loaded solid lipid nanoparticles (SLNs) and to predict their cellular transport across Caco-2 cell monolayers. Zanamivir-loaded SLNs were prepared by a double emulsion solvent evaporation method. The effects of process variables on the mean particle size and zeta potential of SLNs were investigated and the physicochemical properties of SLNs were characterized. In addition, the cytotoxicity and transport ability of SLNs were also studied in Caco-2 cell model. The mean particle size of drug-loaded SLNs was significantly affected by the process variables. The SLNs were prepared using glyceryl monosterate (1% polyvinyl alcohol (PVA) or 1.5% poloxamer 188 as surfactant) had a regular shape with a relatively lower mean particle size (324.2 and 224.9 nm, respectively), higher encapsulation efficacy (55.7 and 42.4%, respectively) and sustained drug release over 12h. The crystalline form of drug had been partly changed and no physicochemical interaction had occurred between drug and carriers in SLNs. The cell viability was approximately 100% even at a high concentration of blank SLNs. There was no remarkable difference in drug permeation between drug-loaded SLNs and drug solution at 2h, while drug-loaded SLNs showed a significant decrease in drug permeation compared with the drug solution at 4h. The process variables of zanamivir-loaded SLNs were successfully optimized in this study. However, these SLNs significantly reduced the transport ability of zanamivir across Caco-2 cell monolayers. Further studies are needed to fully understand the real absorption mechanism of developed SLNs. Copyright © 2014 Elsevier B.V. All rights reserved.

  2. Affective and ergonomic quality of a new bedding product

    OpenAIRE

    Ayas Pinar, Ebru

    2008-01-01

    It is essential that design of bed clothes in healthcare and other industries e.g. hospitality are suitable for the personnel when they perform bedding tasks. The bed clothes are important not just for patients’ experience of healthcare service, but also for serving as tools for nurses satisfaction and performance in the bed making task. Ergonomics and work load of the nurses are directly affected from design and development of product characteristics (material, weight etc.) and related tasks...

  3. Functional characterisation and cell specificity of BvSUT1, the transporter that loads sucrose into the phloem of sugar beet (Beta vulgaris L.) source leaves.

    Science.gov (United States)

    Nieberl, P; Ehrl, C; Pommerrenig, B; Graus, D; Marten, I; Jung, B; Ludewig, F; Koch, W; Harms, K; Flügge, U-I; Neuhaus, H E; Hedrich, R; Sauer, N

    2017-05-01

    Sugar beet (Beta vulgaris L.) is one of the most important sugar-producing plants worldwide and provides about one third of the sugar consumed by humans. Here we report on molecular characterisation of the BvSUT1 gene and on the functional characterisation of the encoded transporter. In contrast to the recently identified tonoplast-localised sucrose transporter BvTST2.1 from sugar beet taproots, which evolved within the monosaccharide transporter (MST) superfamily, BvSUT1 represents a classical sucrose transporter and is a typical member of the disaccharide transporter (DST) superfamily. Transgenic Arabidopsis plants expressing the β-GLUCURONIDASE (GUS) reporter gene under control of the BvSUT1-promoter showed GUS histochemical staining of their phloem; an anti-BvSUT1-antiserum identified the BvSUT1 transporter specifically in phloem companion cells. After expression of BvSUT1 cDNA in bakers' yeasts (Saccharomyces cerevisiae) uptake characteristics of the BvSUT1 protein were studied. Moreover, the sugar beet transporter was characterised as a proton-coupled sucrose symporter in Xenopus laevis oocytes. Our findings indicate that BvSUT1 is the sucrose transporter that is responsible for loading of sucrose into the phloem of sugar beet source leaves delivering sucrose to the storage tissue in sugar beet taproot sinks. © 2017 German Botanical Society and The Royal Botanical Society of the Netherlands.

  4. Road transport management system: a self regulation initiative to promote load optimisation, vehicle maintenance and driver wellness in heavy vehicle transport in South Africa

    CSIR Research Space (South Africa)

    Nordengen, Paul A

    2008-04-01

    Full Text Available vehicle transport industry through a Road Transport Management System (RTMS) with the aim of contributing to the road authorities’ efforts to address the above problems. During 2003 a heavy vehicle accreditation scheme was developed and implemented...

  5. Formation and development of a breaker bar under regular waves. Part 2: Sediment transport and morphology

    DEFF Research Database (Denmark)

    Jacobsen, Niels Gjøl; Fredsøe, Jørgen

    2014-01-01

    In Part 2 of this work, the hydrodynamic model described in Part 1 is applied for the simulation of sediment transport and the associated morphological development of breaker bars. The sediment description is split into bed load and suspended load, and like the hydrodynamics the sediment transport...... is phase-resolved in order to get on- and offshore directed contributions to the sediment transport from phase lags between the suspended sediment and the hydrodynamics.First, the sediment transport over a morphologically fixed bed of a constant slope is considered, and the transport rates are discussed......) is discussed relative to the reference simulation.The coupling between sediment transport rate and morphology is analysed and discussed. © 2014 Elsevier B.V....

  6. Calculation of radiation doses and thermal loads for specific situations that may occur during the transport and storage of spent fuel assemblies from the Rossendorf reactor

    International Nuclear Information System (INIS)

    Seifert, E.

    1995-01-01

    The CAeSAR-III transfer cask and the CASTOR MTR 2 transport and storage cask have been selected for accommodating the spent fuel assemblies from the Rossendorf reactor. The fuel assemblies are packed into the loading units consisting of Al cylinders provided with the suitable gaps for insertion of the spent fuel, according to the various types of fuel elements (EK10, WWR-M, WWR-M2, tubular elements). From among the various types of loading units, only type A designed for accepting 21 single fuel assemblies ( or 7 triple elements) of WWR-M or WWR-M2 is of significance in this context, as they represent the covering neutron and gamma source taken as the radiation source for the calculations. The CAeSAR cask can accommodate one of these loading units, and the CASTOR seven. The dose calculations performed with the MCNP Monte-Carlo code (equivalent dose rate) refer to the loaded casks and some hypothetical situations occurring during loading. The thermal load calculations include the heat-up curve in the event of ''Fire'' in the CASTOR cask, and the stationary temperature distribution in the CASTOR cask due to internal heat generation ( darioactive decay of the inserted fuel assemblies). The HEATING program is used for this purpose. (orig.) [de

  7. The macroinvertebrate fauna of the Młynne stream (Polish Carpathians in the aspect of the bed load transport and water quality

    Directory of Open Access Journals (Sweden)

    Oglęcki Paweł

    2015-12-01

    Full Text Available Fauna makrobezkregowa na tle transportu rumowiska dennego oraz jakości wody w potoku Młynne w Karpatach Polskich. W artykule poruszono temat składu osadów dennych oraz transportu zawiesiny w potoku górskim. Badania przeprowadzono na potoku Młynne w Gorcach. Płynie on częściowo korytem naturalnym, a częściowo uregulowanym poprzez kaskady. Zawiesina denna jest akumulowana w zbiorniku powyżej zapory i pod względem jakościowym różni się od tej gromadzącej się na kaskadach. Fauna bezkręgowa jest dobrym wskaźnikiem zmian hydromorfologicznych i ich wpływu na ekosystem. Bogactwa gatunkowe potoku Młynne jest nieco większe niż innych badanych cieków górskich i podgórskich, ale mniejsze w porównaniu z większymi rzekami. Liczba taksonów na odcinkach naturalnych jest ponaddwukrotnie większa niż na uregulowanych, przy większym udziale gatunków bardzo dużych wymaganiach siedliskowych i dużych wartościach wskaźnika BMWP-PL. W pracy poruszono problem przyjaznych środowisku rozwiązań technicznych przy różnych rodzajach działalności ludzkiej w dolinach rzek górskich i podgórskich, mogących korzystnie wpływać zarówno na dobro człowieka, jak różnorodność biologiczną i odporność ekosystemu na niekorzystne czynniki zewnętrzne.

  8. Modeling sediment transport with an integrated view of the biofilm effects

    Science.gov (United States)

    Fang, H. W.; Lai, H. J.; Cheng, W.; Huang, L.; He, G. J.

    2017-09-01

    Most natural sediment is invariably covered by biofilms in reservoirs and lakes, which have significant influence on bed form dynamics and sediment transport, and also play a crucial role in natural river evolution, pollutant transport, and habitat changes. However, most models for sediment transport are based on experiments using clean sediments without biological materials. In this study, a three-dimensional mathematical model of hydrodynamics and sediment transport is presented with a comprehensive consideration of the biofilm effects. The changes of the bed resistance mainly due to the different bed form dynamics of the biofilm-coated sediment (biosediment), which affect the hydrodynamic characteristics, are considered. Moreover, the variations of parameters related to sediment transport after the biofilm growth are integrated, including the significant changes of the incipient velocity, settling velocity, reference concentration, and equilibrium bed load transport rate. The proposed model is applied to evaluate the effects of biofilms on the hydrodynamic characteristics and sediment transport in laboratory experiments. Results indicate that the mean velocity increases after the biofilm growth, and the turbulence intensity near the river bed decreases under the same flow condition. Meanwhile, biofilm inhibits sediment from moving independently. Thus, the moderate erosion is observed for biosediment resulting in smaller suspended sediment concentrations. The proposed model can reasonably reflect these sediment transport characteristics with biofilms, and the approach to integration of the biological impact could also be used in other modeling of sediment transport, which can be further applied to provide references for the integrated management of natural aqueous systems.

  9. ALARA Principle Application for Loading Spent Nuclear Fuel Assemblies from Nuclear Research Reactor WR-S Mergal-Bucharest Romania into Transportation Casks

    International Nuclear Information System (INIS)

    Dragusin, M.

    2009-01-01

    Safety implementation of Spent Nuclear Fuels Assemblies (SNFA) handling procedures at the WR-S reactor site is ensured by technical perfection and reliability of equipment, monitoring of its condition, qualification and discipline of personnel as well as organization and execution of work complied with requirements of regulatory documents, process procedures, guidance and manuals. The personnel training for execution loading of SNF FAs is other important aspect for radiation protection and safely activities. Estimations carried out using Micro Shield software show that maximal dose rate upon working site when loading four FAs into basket of cask will not exceed 1.7 and 956;Sv/h, excluding natural radiation. Radiation Safety Analyses estimates for loading 70 SNFA in 18 transportation casks are: maximal individual dose: 4274.7 and 956;Sv, maximal expected collective dose persons: 17 031.2 man and 956;Sv. By application ALARA principle with technical and administrative measures the loading process developed in the following conditions: maximal individual dose: 68 and 956;Sv, the collective dose persons: 732 man and 956;Sv. The work will presented the technical measures and procedures applied in loading process.

  10. RANS-based simulation of wave-induced sheet-flow transport of graded sediments

    DEFF Research Database (Denmark)

    Calistan, Ugur; Fuhrman, David R.

    2017-01-01

    A one-dimensional vertical (1DV) turbulence-closure flow model, coupled with sediment transport capabilities,is extended to incorporate graded sediment mixtures. The hydrodynamic model solves the horizontalcomponent of the incompressible Reynolds-averaged Navier–Stokes (RANS) equations coupled...... with k–ωturbulence closure. The sediment transport description includes both bed and suspended load descriptions. Socalledhigh-concentration effects (turbulence damping and hindered settling velocities) are likewise included.The sediment transport model treats the bed and suspended load individually....... The sediment transport model is validated against sheet-flow experimentaloscillatory tunnel measurements beneath velocity-skewed wave signals, and demonstrates similar accuracy(transport rates generally within a factor of two) for both graded and uniform sands. The model is likewisevalidated against...

  11. Transportation

    International Nuclear Information System (INIS)

    Anon.

    1998-01-01

    Here is the decree of the thirtieth of July 1998 relative to road transportation, to trade and brokerage of wastes. It requires to firms which carry out a road transportation as well as to traders and to brokers of wastes to declare their operations to the prefect. The declaration has to be renewed every five years. (O.M.)

  12. Influence of Housing System and Number of Transported Animals on Transport-induced Mortality in Slaughter Pigs

    Directory of Open Access Journals (Sweden)

    Eva Voslářová

    2010-01-01

    Full Text Available The study monitored the effect of the housing system and the number of animals transported together on transport-induced mortality of slaughter pigs in the Czech Republic in the period from 2004 to 2008. Concerning the type of housing during the fattening, the lowest mortality rate during the subsequent transport to slaughter houses was detected among pigs fattened on solid floor (0.047% and on deep bedding (0.084%. The highest mortality during transport was detected among pigs fattened on fully or partially slatted floor (0.139%, a significant difference (p p < 0.01 compared to the load sizes of up to 40 animals.

  13. Lumbosacral loads in bedmaking.

    Science.gov (United States)

    Milburn, P D; Barrett, R S

    1999-06-01

    The purpose of this study was to determine whether the introduction of larger and heavier beds which were lower to the floor increased the physical stress on employees responsible for room cleaning and bedmaking in the hospitality industry. More specifically, this study assessed the effect of bed size (single, double and king) and bed height (460 and 560 mm) on dynamic and static estimates of L5/S1 compression force and static L5/S1 shear force for six simulated components of the overall bedmaking task. Results confirmed the view that static models severely underestimate the loads on the lumbar spine under inertial lifting conditions, and also indicated that: (i) tasks with the greatest hand loads were not necessarily associated with the greatest spinal loads due to differences in the way each task was performed; (ii) L5/S1 loads produced during bedmaking may exceed recommended safe lifting limits for certain task-size height combinations; and (iii) the use of larger and heavier beds in the hospitality industry imposes increased loads on the lumbar spine. The investigation of alternative work practices designed to minimise loads on the lumbar spine is recommended.

  14. Used Nuclear Fuel Loading and Structural Performance Under Normal Conditions of Transport - Modeling, Simulation and Experimental Integration RD&D Plan

    Energy Technology Data Exchange (ETDEWEB)

    Adkins, Harold E. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2013-04-01

    Under current U.S. Nuclear Regulatory Commission regulation, it is not sufficient for used nuclear fuel (UNF) to simply maintain its integrity during the storage period, it must maintain its integrity in such a way that it can withstand the physical forces of handling and transportation associated with restaging the fuel and moving it to treatment or recycling facilities, or a geologic repository. Hence it is necessary to understand the performance characteristics of aged UNF cladding and ancillary components under loadings stemming from transport initiatives. Researchers would like to demonstrate that enough information, including experimental support and modeling and simulation capabilities, exists to establish a preliminary determination of UNF structural performance under normal conditions of transport (NCT). This research, development and demonstration (RD&D) plan describes a methodology, including development and use of analytical models, to evaluate loading and associated mechanical responses of UNF rods and key structural components. This methodology will be used to provide a preliminary assessment of the performance characteristics of UNF cladding and ancillary components under rail-related NCT loading. The methodology couples modeling and simulation and experimental efforts currently under way within the Used Fuel Disposition Campaign (UFDC). The methodology will involve limited uncertainty quantification in the form of sensitivity evaluations focused around available fuel and ancillary fuel structure properties exclusively. The work includes collecting information via literature review, soliciting input/guidance from subject matter experts, performing computational analyses, planning experimental measurement and possible execution (depending on timing), and preparing a variety of supporting documents that will feed into and provide the basis for future initiatives. The methodology demonstration will focus on structural performance evaluation of

  15. Fluidized Bed Gasification as a Mature And Reliable Technology for the Production of Bio-Syngas and Applied in the Production of Liquid Transportation Fuels : A Review

    NARCIS (Netherlands)

    Siedlecki, M.; De Jong, W.; Verkooijen, A.H.M.

    2011-01-01

    Biomass is one of the renewable and potentially sustainable energy sources and has many possible applications varying from heat generation to the production of advanced secondary energy carriers. The latter option would allow mobile services like the transportation sector to reduce its dependency on

  16. Downstream effects of the Pelton-Round Butte hydroelectric project on bedload, transport, channel morphology, and channel-bed texture, lower Deschutes River, Oregon.

    Science.gov (United States)

    Heidi Fassnacht; Ellen M. McClure; Gordon E. Grant; Peter C. Klingeman

    2003-01-01

    Field, laboratory, and historical data provide the basis for interpreting the effects of the Pelton-Round Butte dam complex on the surface water hydrology and geomorphology of the lower Deschutes River, Oregon, USA. The river's response to upstream impoundment and flow regulation is evaluated in terms of changes in predicted bedload transport rates, channel...

  17. Transportation

    National Research Council Canada - National Science Library

    Allshouse, Michael; Armstrong, Frederick Henry; Burns, Stephen; Courts, Michael; Denn, Douglas; Fortunato, Paul; Gettings, Daniel; Hansen, David; Hoffman, Douglas; Jones, Robert

    2007-01-01

    .... The ability of the global transportation industry to rapidly move passengers and products from one corner of the globe to another continues to amaze even those wise to the dynamics of such operations...

  18. The Theoretical Basis of the Concept of Using the Controlled Pyrotechnical Reaction Method as an Energy Source in Transportation from the Sea Bed

    Directory of Open Access Journals (Sweden)

    Wiktor Filipek

    2017-12-01

    Full Text Available In recent years we have observed the global growing interest in undersea exploitation of mineral deposits. Research on various concepts of operating systems on the seabed has been conducted, where different methods of transporting excavated material from the bottom to the surface are used. Great depths, where there are the most interesting resources (eg. IOM lot for the Clarion-Clipperton 4500 m set very high technical and technological demands which results in intensive search for solutions. The authors of the paper want to explain the concept of the use of pyrotechnic materials for transportation in the aquatic environment. The presented method is designed for the cyclic transport from great depths (less than 200 m from the seabed. The principle of operation of the relay unit is based on the change in the average density of the entire module which is inseparably connected with the force of buoyancy acting on the submerged body. Changing the density of the whole module to the given depth of immersion is strictly dependent on the amount of energy supplied to the system by a power source in the form of a controlled pyrotechnic reaction. However, during the ascent energy demand decreases. The problem of transport of spoil from depth not only boils down to such considerations as initiation of the process of ascent. One should also consider how to use the excess energy occurring during the movement of the object toward the surface. The authors of the paper present the concept of making the transport of cyclic depths (less than 200 m from the seabed taking into account the optimal use of energy from controlled pyrotechnic reaction.

  19. Updated Performance Evaluation of the ISS Water Processor Multifiltration Beds

    Science.gov (United States)

    Bowman, Elizabeth M.; Carter, Layne; Carpenter, Joyce; Orozco, Nicole; Weir, Natalee; Wilson, Mark

    2014-01-01

    The ISS Water Processor Assembly (WPA) produces potable water from a waste stream containing humidity condensate and urine distillate. The primary treatment process is achieved in the Multifiltration Beds, which include adsorbent media and ion exchange resin for the removal of dissolved organic and inorganic contaminants. Two Multifiltration Beds (MF Beds) were replaced on ISS in July 2010 after initial indication of inorganic breakthrough of the first bed and an increasing Total Organic Carbon (TOC) trend in the product water. The first bed was sampled and analyzed Sept 2011 through March 2012. The second MF Bed was sampled and analyzed June 2012 through August 2012. The water resident in the both beds was analyzed for various parameters to evaluate adsorbent loading, performance of the ion exchange resin, microbial activity, and generation of leachates from the ion exchange resin. Portions of the adsorbent media and ion exchange resin were sampled and subsequently desorbed to identify the primary contaminants removed at various points in the bed in addition to microbial analysis. Analysis of the second bed will be compared to results from the first bed to provide a comprehensive overview of how the Multifiltration Beds function on orbit. New data from the second bed supplements the analysis of the first bed (previously reported) and gives a more complete picture of breakthrough compounds, resin breakdown products, microbial activity, and difficult to remove compounds. The results of these investigations and implications to the operation of the WPA on ISS are documented in this paper.

  20. Rans-Based Numerical Simulation of Wave-Induced Sheet-Flow Transport of Graded Sediments

    DEFF Research Database (Denmark)

    Fuhrman, David R.; Caliskan, Ugur

    An existing one-dimensional vertical (1DV) turbulence-closure flow model, coupled with sediment transport capabilities, is extended to incorporate graded sediment mixtures. The hydrodynamic model solves the horizontal component of the incompressible Reynolds-averaged Navier–Stokes (RANS) equations...... coupled with k–ω turbulence closure. In addition to standard bed and suspended load descriptions, the sediment transport model incorporates so-called high-concentration effects (turbulence damping and hindered settling velocities). The sediment transport model treats the bed and suspended load......, and then translated to a common level, which conveniently enables use of a single computational grid for the simulation of suspended sediments. Parametric study shows that these effects combine to help alleviate an otherwise systematic tendency towards over- and under- predicted transport rates for fine and coarse...

  1. Analysis of circulating fluidized bed combustion technology

    Energy Technology Data Exchange (ETDEWEB)

    Furusawa, Takehiko; Shimizu, Tadaaki; Yang, Guilin

    1987-05-20

    Fluidized bed combustors are commercialized as a technology to combust solid fuels with higher efficiency and lower emission and have functions of both combustion and simultaneous desulfurization and NOx reduction with dense phase fluidized beds but it is not so easy to realize these problems. The technology of circulating fluidized bed coal combustion is expected to offer potential break-through of various problems. But the details are not reported so far. Quantitative analysis of present situations was conducted and future problems were shown with officially available informations. This analysis includes the circulating rate and loading of solids, heat recovery and heat transfer rate as a function of loading of solids, the design of cyclones related to high solid concentration within the combustor, sulfur retention with reduced Ca/S ratio and problems related to NOx reduction to be developed in future. (51 refs, 23 figs, 8 tabs)

  2. INTRODUCTION Sandstone beds within Auchi locality are the ...

    African Journals Online (AJOL)

    alternating sequence of red, brown, and grayish colours. There are also few intercalations of thin fine grained friable sandstone whose contact with the shale bed is marked by load structures. Worm burrows were also found at the upper section of the shale beds and extend into the overlying sandstone unit. The tabular cross ...

  3. SIMULATION OF TEMPERATURE AND TRANSPORT LOAD IMPACT ON FORMATION AND DEVELOPMENT OF CRACKS ON ASPHALT-CONCRETE ROAD SURFACES

    OpenAIRE

    I. S. Melnikova

    2012-01-01

    An analysis of statistical data has shown that about 60 % of all types of road surface destructions and damages in the Republic of Belarus are attributed to cracks (separate, frequent and cracks network). The process of cracks formation in the asphalt concrete pavement is rather complicated and it is affected by a number of factors. The most important and determining factors are character and value of traffic loads, temperature action, road pavement structure, properties of materials used for...

  4. Simulating an Impact of Road Network Improvements on the Performance of Transportation Systems under Critical Load: Agent-based Approach

    NARCIS (Netherlands)

    Milevich, D.; Melnikov, V.; Karbovskii, V.; Krzhizhanovskaya, V.

    2016-01-01

    In this paper, we analyze the impact of planned road network development on the dynamics of the automobile transportation system during the departure of visitors after the semifinal match of the 2018 FIFA World Cup, which will take place in the newly built stadium on Krestovsky Island. To perform

  5. Transportation studies: 40-MM collider dipole magnets

    International Nuclear Information System (INIS)

    Daly, E.

    1992-01-01

    Several fully functional 40-mm Collider Dipole Magnets (CDM) were instrumented with accelerometers to monitor shock and vibration loads during transport. The magnets were measured with optical tooling telescopes before and after transport. Changes in mechanical alignment due to shipping and handling were determined. The mechanical stability of the cryogen lines were checked using the same method. Field quality and dipole angle were measured warm before and after transport to determine changes in these parameters. Power spectra were calculated for accelerometers located on the cold mass, vacuum vessel, and trailer bed. Where available, plots of field quality and dipole roll both before and after were created. Shipping loads measured were largest in the vertical direction, where most of the structural deformation of the magnet was evident. It was not clear that magnetic performance was affected by the shipping and handling environment

  6. Fluid-bed combustion

    Energy Technology Data Exchange (ETDEWEB)

    Hunt, G.; Schoebotham, N.

    1981-02-01

    In Energy Equipment Company's two-stage fluidized bed system, partial combustion in a fluidized bed is followed by burn-off of the generated gases above the bed. The system can be retrofitted to existing boilers, and can burn small, high ash coal efficiently. It has advantages when used as a hot gas generator for process drying. Tests on a boiler at a Cadbury Schweppes plant are reported.

  7. A laboratory apparatus to measure clast-bed contact forces

    Science.gov (United States)

    Cohen, D.

    2007-12-01

    Glacier dynamics, sediment transport, and erosion are controlled in part by processes occurring at the interface between basal ice and bedrock. One critical parameter is the contact force between a clast and the bedrock. This force affects many processes such as basal friction which regulates sliding speed, slip resistance which influences basal shear stress and may cause micro-seismic events associated with slip instabilities, abrasion which controls rates of erosion, landscape evolution, and production of sediments. Despite field and laboratory evidences indicating that contact forces may be up to one order of magnitude higher than estimated from leading theories, no studies have yet measured with precision the magnitude of contact forces and how contact forces vary as a function of key glaciological variables such as basal melt rate and effective pressure. An apparatus was designed to make two independent measurements: (1) the contact force between a clast and a hard bed as a function of melt rate and effective pressure; (2) the drag force on an identical clast away from the bed as a function of the ice speed. The contact force differs from the drag force because of the presence of the bed which modifies the ice flow field. Measurement (2) is necessary to estimate the rheological properties of the ice and to quantify wall- (bed) effects on the drag force. The apparatus consists of a hydraulic press that pressurizes an ice cylinder, 24~cm high and 20~cm in diameter, to 1.0 - 1.5~MPa. The ice cylinder is contained inside a polycarbonate vessel. Above and below the ice cylinder are three disks: an aluminum disk sandwiched between two Delrin disks. The aluminum disks are hollow and used to circulate a fluid at a controlled temperature. The Delrin disks are used to isolate the ice from the cold room and to control the flow of heat to the ice block. The ice is kept at the melting temperature by circulating a fluid in channels inside the polycarbonate vessel and in the

  8. Long range transport of fine grained sediments on Mars: Atmospheric dust loading, as inferred from Viking Lander imaging data

    Science.gov (United States)

    Pollack, J. B.; Colburn, D. S.

    1984-01-01

    During the first Viking year, two global dust storms occurred and they contributed about 90% of the dust suspended in the Martian atmosphere on a global average, over the course of this year. The remainder was due to the cumulative effect of local dust storms. When globally distributed, the amount of suspended dust introduced into the atmosphere this Martian year was about 5x10(-3) g/sq cm. This mass loading was derived from the incremental optical depths measured over this year and estimates of the mean size of the dust particles (2.5 microns). During the second Martian year, global dust storms were far more muted than during the first year. No near perihelion dust storm occurred, and a somewhat weaker dust storm may have occurred near the start of the spring season in the Southern Hemisphere, at about the same time that the first global dust storm of the first year occurred. Thus, the dust loading derived for the first Martian year may be somewhat higher than the average over many Martian years, a conclusion that appears to be supported by preliminary studies of Martian years beyond the second Viking year on Mars.

  9. SIMULATION OF TEMPERATURE AND TRANSPORT LOAD IMPACT ON FORMATION AND DEVELOPMENT OF CRACKS ON ASPHALT-CONCRETE ROAD SURFACES

    Directory of Open Access Journals (Sweden)

    I. S. Melnikova

    2012-01-01

    Full Text Available An analysis of statistical data has shown that about 60 % of all types of road surface destructions and damages in the Republic of Belarus are attributed to cracks (separate, frequent and cracks network. The process of cracks formation in the asphalt concrete pavement is rather complicated and it is affected by a number of factors. The most important and determining factors are character and value of traffic loads, temperature action, road pavement structure, properties of materials used for its layers. Some regularities of the cracks formation and development in the asphalt-concrete layers of the pavement have been established on the basis of the physical and mathematical modeling. Application of a finite  element  method for  calculations  has made it possible to determine  numerical values of compressive and tensile stresses arising due to temperature action and traffic load, deflection of road pavement constructive layers. The paper contains recommendations for a road pavement design and repair of asphalt-concrete pavements which have been made on the basis of the obtained data analysis.

  10. Scour and fill in cobble-bedded streams

    OpenAIRE

    Carling, P.A.

    1982-01-01

    Scour and deposition have been measured in two small cobble-bedded upland streams, for two years. Grids of scour chains were inserted in the bed and relocated after the passage of individual hydrographs. Scour, fill and the area of the bed affected by these processes were recorded. The relationship between mean scour or fill and maximum scour or fill is assessed. In addition, the relationship between the depth of scour and the sediment transport rate as bedload is discussed briefly.

  11. Numerical simulations and correlations on the coal -conveying gas flow in pipe for fluidized -bed coal gasification facility

    International Nuclear Information System (INIS)

    Lee, Chan; Lee, Jin Wook; Kwon, Tae Wan; Kim, Gyoo Tae

    2014-01-01

    CFD modeling and simulation are made on the key flow elements, vertical, horizontal pipes and elbow pipes , used in the pneumatic coal -transport system of fluidized -bed gasification test facility. The coal- gas flow inside the flow elements are modeled by combining Reynolds -stress Averaged Navier- Stokes equations Solver (RANS), k- ε turbulence model and Discrete Phase Model (DPM) in the ANSYS Fluent code. Using the developed coal -gas flow analysis model, computations are carried out to investigate the gas flow path, the coal particle behavior and the pressure loss characteristics in flow element at various coal/ gas loading ratio and coal mass flux. The present prediction results show the coal -gas flow behavior of each flow element is changed from dilute -flow to dense -flow pattern at a specific coal/gas loading ratio where pressure loss is abruptly increased. From the numerical results, the present study also provides the limiting coal/gas loading conditions to secure stable coal feeding and the correlations for pressure losses in horizontal, vertical and elbow pipes, which can be suitable for the design guidelines of actual fluidized -bed coal gasification. Key words : Pneumatic Coal -Transport; Coal -Gas Flow, Dense Phase Flow; Dilute Phase Flow; Pressure Loss; Coal/Gas Loading Ratio; Correlation

  12. Simultaneous Vehicle and Crew Routing and Scheduling for Partial- and Full-Load Long-Distance Road Transport

    Directory of Open Access Journals (Sweden)

    Michael Drexl

    2013-11-01

    Full Text Available This paper studies a simultaneous vehicle and crew routing and scheduling problem arising in long-distance road transport in Europe: Pickup-and-delivery requests have to be fulfilled over a multi-period planning horizon by a heterogeneous fleet of trucks and drivers. Typically, in the vehicle routing literature, a fixed assignment of a driver to a truck is assumed. In our approach, we abandon this assumption and allow truck/driver changes at geographically dispersed relay stations. This offers greater planning flexibility and allows a better utilization of trucks, but also creates intricate interdependencies between trucks and drivers and requires the synchronization of their routes. A solution heuristic based on a two-stage decomposition of the problem is developed, taking into account European Union social legislation for drivers, and computational experiments using real-world data provided by a major German forwarder are presented and analyzed. The obtained results suggest that for the vehicle and driver cost structure prevalent in Western Europe and for transport requests that are not systematically acquired to complement one another, no cost savings are possible through simultaneous vehicle and crew routing and scheduling, although no formal proof of this fact is possible.

  13. Cardiac atrophy after bed rest and spaceflight

    Science.gov (United States)

    Perhonen, M. A.; Franco, F.; Lane, L. D.; Buckey, J. C.; Blomqvist, C. G.; Zerwekh, J. E.; Peshock, R. M.; Weatherall, P. T.; Levine, B. D.

    2001-01-01

    Cardiac muscle adapts well to changes in loading conditions. For example, left ventricular (LV) hypertrophy may be induced physiologically (via exercise training) or pathologically (via hypertension or valvular heart disease). If hypertension is treated, LV hypertrophy regresses, suggesting a sensitivity to LV work. However, whether physical inactivity in nonathletic populations causes adaptive changes in LV mass or even frank atrophy is not clear. We exposed previously sedentary men to 6 (n = 5) and 12 (n = 3) wk of horizontal bed rest. LV and right ventricular (RV) mass and end-diastolic volume were measured using cine magnetic resonance imaging (MRI) at 2, 6, and 12 wk of bed rest; five healthy men were also studied before and after at least 6 wk of routine daily activities as controls. In addition, four astronauts were exposed to the complete elimination of hydrostatic gradients during a spaceflight of 10 days. During bed rest, LV mass decreased by 8.0 +/- 2.2% (P = 0.005) after 6 wk with an additional atrophy of 7.6 +/- 2.3% in the subjects who remained in bed for 12 wk; there was no change in LV mass for the control subjects (153.0 +/- 12.2 vs. 153.4 +/- 12.1 g, P = 0.81). Mean wall thickness decreased (4 +/- 2.5%, P = 0.01) after 6 wk of bed rest associated with the decrease in LV mass, suggesting a physiological remodeling with respect to altered load. LV end-diastolic volume decreased by 14 +/- 1.7% (P = 0.002) after 2 wk of bed rest and changed minimally thereafter. After 6 wk of bed rest, RV free wall mass decreased by 10 +/- 2.7% (P = 0.06) and RV end-diastolic volume by 16 +/- 7.9% (P = 0.06). After spaceflight, LV mass decreased by 12 +/- 6.9% (P = 0.07). In conclusion, cardiac atrophy occurs during prolonged (6 wk) horizontal bed rest and may also occur after short-term spaceflight. We suggest that cardiac atrophy is due to a physiological adaptation to reduced myocardial load and work in real or simulated microgravity and demonstrates the plasticity

  14. Fluidized bed incinerator development

    International Nuclear Information System (INIS)

    Ziegler, D.L.; Johnson, A.J.

    1976-01-01

    A fluidized bed incinerator is being developed for burning rad contaminated solid and liquid waste materials. In situ neutralization of acid gases by the bed material, catalytic afterburning, and gas filtration are used to produce a clean flue gas without the use of aqueous scrubbing

  15. Sediment supply versus local hydraulic controls on sediment transport and storage in a river with large sediment loads

    Science.gov (United States)

    Dean, David J.; Topping, David J.; Schmidt, John C.; Griffiths, Ronald E.; Sabol, Thomas A.

    2016-01-01

    The Rio Grande in the Big Bend region of Texas, USA, and Chihuahua and Coahuila, Mexico, undergoes rapid geomorphic changes as a result of its large sediment supply and variable hydrology; thus, it is a useful natural laboratory to investigate the relative importance of flow strength and sediment supply in controlling alluvial channel change. We analyzed a suite of sediment transport and geomorphic data to determine the cumulative influence of different flood types on changing channel form. In this study, physically based analyses suggest that channel change in the Rio Grande is controlled by both changes in flow strength and sediment supply over different spatial and temporal scales. Channel narrowing is primarily caused by substantial deposition of sediment supplied to the Rio Grande during tributary-sourced flash floods. Tributary floods have large suspended-sediment concentrations, occur for short durations, and attenuate rapidly downstream in the Rio Grande, depositing much of their sediment in downstream reaches. Long-duration floods on the mainstem have the capacity to enlarge the Rio Grande, and these floods, released from upstream dams, can either erode or deposit sediment in the Rio Grande depending upon the antecedent in-channel sediment supply and the magnitude and duration of the flood. Geomorphic and sediment transport analyses show that the locations and rates of sand erosion and deposition during long-duration floods are most strongly controlled by spatial changes in flow strength, largely through changes in channel slope. However, spatial differences in the in-channel sediment supply regulate sediment evacuation or accumulation over time in long reaches (greater than a kilometer).

  16. Characterizing and simulating sediment loads and transport in the lower part of the San Antonio River Basin

    Science.gov (United States)

    Banta, J. Ryan; Ockerman, Darwin J.; Crow, Cassi; Opsahl, Stephen P.

    2015-01-01

    This extended abstract is based on the U.S. Geological Survey Scientific Investigations Reports by Crow et al. (2013) and Banta and Ockerman (2014). Suspended sediment in rivers and streams can play an important role in ecological health of rivers and estuaries and consequently is an important issue for water-resource managers. The quantity and type of suspended sediment can affect the biological communities (Wood and Armitage, 1997), the concentration and movement of natural constituents and anthropogenic contaminants (Moran and others, 2012), and the amount of sediment deposition in coastal environments (Milliman and Meade, 1983). To better understand suspended-sediment characteristics in the San Antonio River Basin, the U.S. Geological Survey (USGS), in cooperation with the San Antonio River Authority and Texas Water Development Board, conducted a two-phase study to (1) collect and analyze sediment data to characterize sediment conditions in the San Antonio River downstream of San Antonio, Texas, and (2) develop and calibrate a watershed model to simulate hydrologic conditions and suspended-sediment loads for four watersheds in the San Antonio River Basin, downstream from San Antonio, Texas.

  17. The impact of feeding Cyprinids on river bed sediment structures and grain entrainment

    Science.gov (United States)

    Pledger, A.; Rice, S. P.; Millett, J.

    2012-04-01

    In gravel-bed rivers, between bed-mobilising flood events, surface sediment particles are rearranged by moderate flows, generally into more stable "water-worked" positions characterised by structures of various types, including imbrication and pebble clusters. This surface layer of structured, relatively coarse particles moderates the availability of finer sub-surface sediment and the transfer of mobile material from upstream. The work reported here is focused on understanding how benthic feeding fish (Cyprinids and Salmonids) dismantle surface structures, making particles less stable and potentially rendering vulnerable sub-surface material more mobile. An increase in available, transportable sediment has implications for sediment transport fluxes, reach-scale sediment loads, channel morphology and aquatic habitat. However, almost nothing is known about the impacts of feeding fish on bed sediment structures, entrainment and sediment fluxes. A series of flume experiments will quantify the effects of six different species of fish on sediment structure and grain entrainment. The experiments will consider 1) topographic variations between pre- and post-feeding substrates using DEMs interpolated from laser scans and 2) differences in sediment entrainment from water-worked substrates exposed to feeding fish and control substrates, without fish. Using interpolated DEMs, a variety of structural parameters will be extracted (e.g. imbrication indices) to quantify the impact of each species whilst feeding. Underwater videography techniques will be used to establish entrainment thresholds and transport rates under low critical shear stresses. A second set of flume experiments are planned using a large outdoor flume to investigate the effects of feeding Barbel Barbus barbus on surface structure, to assess how disturbance and sediment mobility vary as a function of species size and shoal density. A final set of field experiments will consider the large-scale, geomorphological

  18. Hybrid modelling of bed-discordant river confluences

    Science.gov (United States)

    Franca, M. J.; Guillén-Ludeña, S.; Cheng, Z.; Cardoso, A. H.; Constantinescu, G.

    2016-12-01

    In fluvial networks, tributaries are the main providers of sediment and water to the main rivers. Furthermore, confluences are environmental hotspots since they provide ecological connectivity and flow and morphology diversity. Mountain confluences, in particular, are characterized by narrow and steep tributaries that provide important sediment load to the confluence, whereas the main channel supplies the dominant flow discharge. This results in a marked bed discordance between the tributary and main channel. This discordance has been observed to be a key feature that alters the dynamics of the confluence, when compared to concordant confluences. The processes of initiation and maintenance of the morphology of confluences is still unknown, and research linking morphodynamics and hydrodynamics of river confluences is required to understand this. Here, a hybrid approach combining laboratory experiments made in a live-bed model of a river confluence, with 3D numerical simulations using advanced turbulence models is presented. We use the laboratory experiments performed by Guillén-Ludeña et al. (2016) for a 70o channel confluence, which focused on sediment transport and morphology changes rather than on the structure of the flow. Highly eddy resolving simulations were performed for two extreme bathymetric conditions, at the start of the experiment and at equilibrium scour conditions. The first allows to understand the initiation mechanisms which will condition later the equilibrium morphology. The second allows to understand the hydrodynamics actions which keep the equilibrium morphology. The patterns of the mean flow, turbulence and dynamics of the large-scale coherent structures, show how the main sediment-entrainment mechanisms evolve during the scour process. The present results contribute to a better understanding of the interaction between bed morphology and flow dynamics at discordant mountain river confluences.

  19. Partitioning and analyzing temporal variability of wash and bed ...

    Indian Academy of Sciences (India)

    In this study, 24 samples of suspended load, bed load and channel material were taken bi-weekly for a period of one year from the Kojour River of the Educational and Research Forest Watershed of Tarbiat Modares University in Iran. The suspended sediment concentration and particle-size distribution were determined.

  20. Sediment Transport

    DEFF Research Database (Denmark)

    Liu, Zhou

    Flow and sediment transport are important in relation to several engineering topics, e.g. erosion around structures, backfilling of dredged channels and nearshore morphological change. The purpose of the present book is to describe both the basic hydrodynamics and the basic sediment transport...... mechanics. Chapter 1 deals with fundamentals in fluid mechanics with emphasis on bed shear stress by currents, while chapter 3 discusses wave boundary layer theory. They are both written with a view to sediment transport. Sediment transport in rivers, cross-shore and longshore are dealt with in chapters 2...

  1. Stowing of packages containing radioactive materials during their road transportation with trucks for loads up to 38 tons

    International Nuclear Information System (INIS)

    Gilles, P.; Chevalier, G.; Pouard, M.; Draulans, J.; Lafontaine, I.

    1986-01-01

    A compilation and a coordination of available standards, regulatory prescriptions and directives on stowing are first presented. Then generated forces resulting from road vehicle deceleration in accidental conditions are searched. The investigation shows that higher dangerous materials transportation probabilities essentially concern front end impacts (51.4 %) and side on impacts (19 %). These accidents occur with a speed of about 80 km/h before the impact and 50 km/h during the crash. During the latter, deceleration values ranging from 20 to 100g could be reached, the mean value could be about 30g. A mathematical model is developed. Experiments are realized with the aims on the one hand, to verify the results obtained from a mathematical model of accident and on the other hand to collect experimental values allowing to work out a code of good practice for the stowing of radioactive materials packages having a maximum weight of about 20 tons. A number of 8 tests has been performed with two types of packagings: lower and higher centre of gravity in front end and side on impacts. In case of a front end impact, the stowing system must be able to absorb entirely the kinetic energy generated by the package deceleration. This means that a tie-down system according to the 2g - 1g - 1g standard is convenient provided that the package is chocked in the direction of the traffic. The damage is proportional to the weight of the vehicle responsible for such side on impact. This weight could be much higher than the package weight. Deceleration values up to 120g have been recorded. As a result, the tie down system similar to the 2g - 1g - 1g standard is convenient, but chocks acting perpendicularly to the direction of the traffic are to be prohibited

  2. Kinetics of deactivation of catalysts for vinyl acetate synthesis in the fluidized-bed reactor: The optimal loading and distribution of zinc acetate in the porous structure of a support

    Energy Technology Data Exchange (ETDEWEB)

    Romanchuk, S.V.; Makhlin, V.A. [Karpov Institute of Physical Chemistry, Moscow (Russian Federation)

    1995-03-01

    The deactivation of a catalyst (zinc acetate on activated carbon) including a change of the phase state of the active component is considered. The mechanism and relevant kinetic model of the deactivation are presented. A degree of thermal decomposition of zinc acetate controls the deactivation rate, which depends on the loading and distribution of zinc acetate in the porous structure of a support. A modeling of the process in an industrial reactor is performed with regard to the deactivation, attrition, and loss of a catalyst. Each carbon support has an optimal loading of zinc acetate (equal to the critical value), which provides both a high activity and stability of catalyst operation. The reasons behind the fast deactivation of the commercial catalyst are revealed. The possibility is demonstrated of extending the life time of a catalyst on available carbon supports by a factor of {approximately}2.5, due to the optimal loading and distribution of the active component in the porous support structure.

  3. Bed rest during pregnancy

    Science.gov (United States)

    ... Belizán JM, Bergel E. Bed rest in singleton pregnancies for preventing preterm birth. Cochrane Database ... and Gynecology, Loma Linda University School of Medicine, Loma Linda Center for Fertility, ...

  4. Enuresis (Bed-Wetting)

    Science.gov (United States)

    ... Symptoms of enuresis Enuresis is when an older child (age 7 or older) wets the bed at night ... feel guilt and embarrassment. It’s true that your child should take responsibility for bedwetting. He or she could do this ...

  5. Particle fuel bed tests

    International Nuclear Information System (INIS)

    Horn, F.L.; Powell, J.R.; Savino, J.M.

    1985-01-01

    Gas-cooled reactors, using packed beds of small diameter coated fuel particles have been proposed for compact, high-power systems. The particulate fuel used in the tests was 800 microns in diameter, consisting of a thoria kernel coated with 200 microns of pyrocarbon. Typically, the bed of fuel particles was contained in a ceramic cylinder with porous metallic frits at each end. A dc voltage was applied to the metallic frits and the resulting electric current heated the bed. Heat was removed by passing coolant (helium or hydrogen) through the bed. Candidate frit materials, rhenium, nickel, zirconium carbide, and zirconium oxide were unaffected, while tungsten and tungsten-rhenium lost weight and strength. Zirconium-carbide particles were tested at 2000 K in H 2 for 12 hours with no visible reaction or weight loss

  6. Modes of sediment transport in channelized water flows with ramifications to the erosion of the Martian outflow channels

    Science.gov (United States)

    Komar, P. D.

    1980-01-01

    The paper discusses application to Martian water flows of the criteria that determine which grain-size ranges are transported as bed load, suspension, and wash load. The results show nearly all sand-sized material and finer would have been transported as wash load and that basalt pebbles and even cobbles could have been transported at rapid rates of suspension. An analysis of the threshold of sediment motion on Mars further indicates that the flows would have been highly competent, the larger flows having been able to transport boulder-sized material. Comparisons with terrestrial rivers which transport hyperconcentration levels of sediments suggest that the Martian water flows could have achieved sediment concentrations up to 70% in weight. Although it is possible that flows could have picked up enough sediment to convert to pseudolaminar mud flows, they probably remained at hyperconcentration levels and fully turbulent in flow character.

  7. Innovative rock bed construction

    Energy Technology Data Exchange (ETDEWEB)

    Cook, J.

    1983-06-01

    A general discussion of the use of rock beds for heating and cooling thermal storage is particularized for design and construction in Phoenix, Arizona. The rock bed parameters for three two-story condominium apartments constructed in 1982 are discussed, including sizing criteria and original construction details. A revised construction method using gabions that are self-supporting chain link cylinders provided a much more economical construction method as well as other advantages of speed and structural flexibility.

  8. An Apparatus for Bed Material Sediment Extraction From Coarse River Beds in Large Alluvial Rivers

    Science.gov (United States)

    Singer, M. B.; Adam, H.; Cooper, J.; Cepello, S.

    2005-12-01

    Grain size distributions of bed material sediment in large alluvial rivers are required in applications ranging from habitat mapping, calibration of sediment transport models, high resolution sediment routing, and testing of existing theories of longitudinal and cross steam sediment sorting. However, characterizing bed material sediment from coarse river beds is hampered by difficulties in sediment extraction, a challenge that is generally circumvented via pebble counts on point bars, even though it is unclear whether the bulk grain size distribution of bed sediments is well represented by pebble counts on bars. We have developed and tested a boat-based sampling apparatus and methodology for extracting bulk sediment from a wide range of riverbed materials. It involves the use of a 0.4 x 0.4 x 0.2 meter stainless steel toothed sampler, called the Cooper Scooper, which is deployed from and dragged downstream by the weight of a jet boat. The design is based on that of a river anchor such that a rotating center bar connected to a rope line in the boat aligns the sampler in the downstream direction, the teeth penetrate the bed surface, and the sampler digs into the bed. The sampler is fitted with lead weights to keep it from tipping over. The force of the sampler `biting' into the bed can be felt on the rope line held by a person in the boat at which point they let out slack. The boat then motors to the spot above the embedded sampler, which is hoisted to the water surface via a system of pulleys. The Cooper Scooper is then clipped into a winch and boom assembly by which it is brought aboard. This apparatus improves upon commonly used clamshell dredge samplers, which are unable to penetrate coarse or mixed bed surfaces. The Cooper Scooper, by contrast, extracts statistically representative bed material sediment samples of up to 30 kilograms. Not surprisingly, the sampler does not perform well in very coarse or armored beds (e.g. where surface material size is on the

  9. Mesoporous anatase TiO2 microspheres with interconnected nanoparticles delivering enhanced dye-loading and charge transport for efficient dye-sensitized solar cells

    International Nuclear Information System (INIS)

    Chu, Liang; Qin, Zhengfei; Zhang, Qiaoxia; Chen, Wei; Yang, Jian; Yang, Jianping; Li, Xing’ao

    2016-01-01

    Graphical abstract: The photoelectrodes of DSSCs consisted of mesoporous anatase TiO 2 microspheres with interconnected nanoparticles. The interconnected nanoparticles enhance dye-loading capacity and charge transport. - Highlights: • The mesoporous anatase TiO 2 microspheres were synthesized by a template-free, one-step fast solvothermal process. • The mesoporous anatase TiO 2 microspheres with interconnected nanoparticles have the advantages of large surface area and connected-structure for electron transfer. • The mesoporous anatase TiO 2 microspheres were further utilized as efficient photoelectrodes for dye-sensitized solar cells. - Abstract: Mesoporous anatase TiO 2 microspheres with interconnected nanostructures meet both large surface area and connected-structure for electron transfer as ideal nano/micromaterials for application in solar cells, energy storage, catalysis, water splitting and gas sensing. In this work, mesoporous anatase TiO 2 microspheres consisting of interconnected nanoparticles were synthesized by template-free, one-step fast solvothermal process, where urea was used as capping agent to control phase and promote oriented growth. The morphology was assembled by nucleation-growth-assembly-mechanism. The mesoporous anatase TiO 2 microspheres with interconnected nanoparticles were further utilized as efficient photoelectrodes of dye-sensitized solar cells (DSSCs), which were beneficial to capacity of dye loading and charge transfer. The power conversion efficiency (PCE) based on the optimized thickness of TiO 2 photoelectrodes was up to 7.13% under standard AM 1.5 G illumination (100 mW/cm 2 ).

  10. Quasi-two-layer morphodynamic model for bedload-dominated problems: bed slope-induced morphological diffusion.

    Science.gov (United States)

    Maldonado, Sergio; Borthwick, Alistair G L

    2018-02-01

    We derive a two-layer depth-averaged model of sediment transport and morphological evolution for application to bedload-dominated problems. The near-bed transport region is represented by the lower (bedload) layer which has an arbitrarily constant, vanishing thickness (of approx. 10 times the sediment particle diameter), and whose average sediment concentration is free to vary. Sediment is allowed to enter the upper layer, and hence the total load may also be simulated, provided that concentrations of suspended sediment remain low. The model conforms with established theories of bedload, and is validated satisfactorily against empirical expressions for sediment transport rates and the morphodynamic experiment of a migrating mining pit by Lee et al. (1993 J. Hydraul. Eng. 119 , 64-80 (doi:10.1061/(ASCE)0733-9429(1993)119:1(64))). Investigation into the effect of a local bed gradient on bedload leads to derivation of an analytical, physically meaningful expression for morphological diffusion induced by a non-zero local bed slope. Incorporation of the proposed morphological diffusion into a conventional morphodynamic model (defined as a coupling between the shallow water equations, Exner equation and an empirical formula for bedload) improves model predictions when applied to the evolution of a mining pit, without the need either to resort to special numerical treatment of the equations or to use additional tuning parameters.

  11. Quasi-two-layer morphodynamic model for bedload-dominated problems: bed slope-induced morphological diffusion

    Science.gov (United States)

    Maldonado, Sergio; Borthwick, Alistair G. L.

    2018-02-01

    We derive a two-layer depth-averaged model of sediment transport and morphological evolution for application to bedload-dominated problems. The near-bed transport region is represented by the lower (bedload) layer which has an arbitrarily constant, vanishing thickness (of approx. 10 times the sediment particle diameter), and whose average sediment concentration is free to vary. Sediment is allowed to enter the upper layer, and hence the total load may also be simulated, provided that concentrations of suspended sediment remain low. The model conforms with established theories of bedload, and is validated satisfactorily against empirical expressions for sediment transport rates and the morphodynamic experiment of a migrating mining pit by Lee et al. (1993 J. Hydraul. Eng. 119, 64-80 (doi:10.1061/(ASCE)0733-9429(1993)119:1(64))). Investigation into the effect of a local bed gradient on bedload leads to derivation of an analytical, physically meaningful expression for morphological diffusion induced by a non-zero local bed slope. Incorporation of the proposed morphological diffusion into a conventional morphodynamic model (defined as a coupling between the shallow water equations, Exner equation and an empirical formula for bedload) improves model predictions when applied to the evolution of a mining pit, without the need either to resort to special numerical treatment of the equations or to use additional tuning parameters.

  12. Sediment loads and transport at constructed chutes along the Missouri River - Upper Hamburg Chute near Nebraska City, Nebraska, and Kansas Chute near Peru, Nebraska

    Science.gov (United States)

    Densmore, Brenda K.; Rus, David L.; Moser, Matthew T.; Hall, Brent M.; Andersen, Michael J.

    2016-02-04

    estimate streamflow within each chute. The sampling design was developed to understand the suspended-sediment differences within each chute and between the chute and the Missouri River main channel during discrete sampling. The sampling design also allowed for site-specific surrogate relations between SSC and turbidity to be developed, which could be used to compute real-time estimates of SSC and sediment loads within the chutes. Real-time estimates of SSC and sediment loads enable a better understanding of sediment transport within the chutes during times when physical samples are not collected, including periods of high flow.

  13. Estimated Loads of Suspended Sediment and Selected Trace Elements Transported through Milltown Reservoir in the Upper Clark Fork Basin, Montana, Water Years 2004-07

    Science.gov (United States)

    Lambing, John H.; Sando, Steven K.

    2008-01-01

    The purpose of this report is to present estimated daily and annual loads of suspended sediment and selected trace elements for water years 2004-07 at two sites upstream and one site downstream from Milltown Reservoir. Milltown Reservoir is a National Priorities List Superfund site in the upper Clark Fork basin of western Montana where sediments enriched in trace elements from historical mining and ore processing have been deposited since the construction of Milltown Dam in 1907. The estimated loads were used to quantify annual net gains and losses (mass balance) of suspended sediment and trace elements within Milltown Reservoir before and after June 1, 2006, which was the start of Stage 1 of a permanent drawdown of the reservoir in preparation for removal of Milltown Dam. This study was done in cooperation with the U.S. Environmental Protection Agency. Daily loads of suspended sediment were estimated for water years 2004-07 by using either high-frequency sampling as part of daily sediment monitoring or regression equations relating suspended-sediment discharge to streamflow. Daily loads of unfiltered-recoverable arsenic, cadmium, copper, iron, lead, manganese, and zinc were estimated by using regression equations relating trace-element discharge to suspended-sediment discharge. Regression equations were developed from data for eriodic water-quality samples collected during water years 2004-07. The equations were applied to daily records of either streamflow or suspended-sediment discharge to produce estimated daily loads. Variations in daily suspended-sediment and trace-element loads generally coincided with variations in streamflow. For most of the period before June 1, 2006, differences in daily loads transported to and from Milltown Reservoir were minor or indicated small amounts of deposition; however, losses of suspended sediment and trace elements from the reservoir occurred during temporary drawdowns in July-August 2004 and October-December 2005. After the

  14. Use of sediment rating curves and optical backscatter data to characterize sediment transport in the Upper Yuba River watershed, California, 2001-03

    Science.gov (United States)

    Curtis, Jennifer A.; Flint, Lorraine E.; Alpers, Charles N.; Wright, Scott A.; Snyder, Noah P.

    2006-01-01

    Sediment transport in the upper Yuba River watershed, California, was evaluated from October 2001 through September 2003. This report presents results of a three-year study by the U.S. Geological Survey, in cooperation with the California Ecosystem Restoration Program of the California Bay-Delta Authority and the California Resources Agency. Streamflow and suspended-sediment concentration (SSC) samples were collected at four gaging stations; however, this report focuses on sediment transport at the Middle Yuba River (11410000) and the South Yuba River (11417500) gaging stations. Seasonal suspended-sediment rating curves were developed using a group-average method and non-linear least-squares regression. Bed-load transport relations were used to develop bed-load rating curves, and bed-load measurements were collected to assess the accuracy of these curves. Annual suspended-sediment loads estimated using seasonal SSC rating curves were compared with previously published annual loads estimated using the Graphical Constituent Loading Analysis System (GCLAS). The percent difference ranged from -85 percent to +54 percent and averaged -7.5 percent. During water year 2003 optical backscatter sensors (OBS) were installed to assess event-based suspended-sediment transport. Event-based suspended-sediment loads calculated using seasonal SSC rating curves were compared with loads calculated using calibrated OBS output. The percent difference ranged from +50 percent to -369 percent and averaged -79 percent. The estimated average annual sediment yield at the Middle Yuba River (11410000) gage (5 tons/mi2) was significantly lower than that estimated at the South Yuba River (11417500) gage (14 tons/mi2). In both rivers, bed load represented 1 percent or less of the total annual load throughout the project period. Suspended sediment at the Middle Yuba River (11410000) and South Yuba River (11417500) gages was typically greater than 85 percent silt and clay during water year 2003, and

  15. State-of-the-art in modeling solute and sediment transport in rivers

    International Nuclear Information System (INIS)

    Sayre, W.W.

    1980-01-01

    This overview is structured around a comprehensive general model based on the conservation of mass principle as applied to dissolved and particulate constituents in rivers, with a few restricted but more specific examples that illustrate the state-of-the-art in modeling typical physical, chemical, and biological processes undergone by selected constituents in rivers. These examples include: simplified one- and two-dimensional formulations focusing on the hydrodynamic advection and dispersion mechanisms; a two-dimensional biochemial oxygen demand-dissolved oxygen model; a one-dimensional polychlorinated biphenyl model that includes uptake and release of constituent by suspended sediment, and deposition and erosion of contaminated particles; and a one-dimensional sediment transport model that accounts for interactions between the flow and the bed, and is capable of tracking dispersing slugs of sediment through cycles of erosion, entrainment, transport in suspension and as bed load, and burial and storage in the bed

  16. Nuclear fuel pellet loading apparatus

    International Nuclear Information System (INIS)

    Gerkey, K.S.

    1979-01-01

    An automatic apparatus for loading a predetermined amount of nuclear fuel pellets into a nuclear fuel element to be used in a nuclear reactor is described. The apparatus consists of a vibratory bed capable of supporting corrugated trays containing rows of nuclear fuel pellets and arranged in alignment with the open ends of several nuclear fuel elements. A sweep mechanism is arranged above the trays and serves to sweep the rows of fuel pellets onto the vibratory bed and into the fuel element. A length detecting system, in conjunction with a pellet stopping mechanism, is also provided to assure that a predetermined amount of nuclear fuel pellets are loaded into each fuel element

  17. The Effect of Bedding Structure on Mechanical Property of Coal

    Directory of Open Access Journals (Sweden)

    Zetian Zhang

    2014-01-01

    Full Text Available The mechanical property of coal, influencing mining activity considerably, is significantly determined by the natural fracture distributed within coal mass. In order to study the effecting mechanism of bedding structure on mechanical property of coal, a series of uniaxial compression tests and mesoscopic tests have been conducted. The experimental results show that the distribution characteristic of calcite particles, which significantly influences the growth of cracks and the macroscopic mechanical properties of coal, is obviously affected by the bedding structure. Specifically, the uniaxial compression strength of coal sample is mainly controlled by bedding structure, and the average peak stress of specimens with axes perpendicular to the bedding planes is 20.00 MPa, which is 2.88 times the average amount of parallel ones. The test results also show a close relationship between the bedding structure and the whole deformation process under uniaxial loading.

  18. Tracing cohesive sediment transportation at river mouths around Tokyo, Japan by Cesium originated from Fukushima Daiichi Power Plant

    Science.gov (United States)

    koibuchi, Y.

    2012-12-01

    Sediment transport at river mouths, which consists of suspended-load and bed-load, has not been fully understood, since bed-load transport of cohesive sand is difficult to observe. Especially, the impact of sediment transport on the total amount of fine-grained cohesive sediment has not been elucidated. Cesium-134 and cesium-137 were spread from the Fukushima Daiichi Nuclear Power Plant (FDNPP) after the earthquake of March 11 of 2011, and attached to the fine-grained sand on the land. The contaminated sand flowed into the river mouths through the rivers possibly due to the complex physical processes in estuarine areas. To evaluate the fine-grained sediment transport around Tokyo and Tokyo Bay, field observations were carried out utilizing radionuclide originated from FDNPP as an effective tracer. The cohesive sediment transport at three different river mouths around Tokyo was successfully quantified. The cohesive sediment transport deposited in the estuary was found to be greatly dependent on the land use, geometry, river discharge and salinity. In addition,the transport driven by the rainfall was minute, and its behavior was quite different from suspended solids. Although further field observations of radionuclide are necessary, it is clear that fine-grained sediment in the bay from rivers already settled on the river mouth by aggregation. The settled sand will not move even in rainfall events. Consequently, the transport of radionuclide to the Pacific Ocean may not occur.; Cesium distribution around Tokyo Bay ; Cesium Concentration in Edogawa river

  19. Prediction of diffuse organic micropollutant loads in streams under changing climatic, socio-economic and technical boundary conditions with an integrated transport model

    Science.gov (United States)

    Honti, Mark; Schuwirth, Nele; Rieckermann, Jörg; Ghielmetti, Nico; Stamm, Christian

    2014-05-01

    Catchments are complex systems where water quantity, quality and the ecological services provided are determined by interacting physical, chemical, biological, economical and social factors. The realization of these interactions led to the prevailing catchment management paradigm: Integrated Water Resources Management (IWRM). IWRM requires considering all these aspects during the design of sustainable resource utilization. Due to the complexity of this task, mathematical modeling plays a key role in IWRM, namely in the evaluation of the impacts of hypothetical scenarios and management measures. Toxicity is a key determinant of the ecological state and as such a focal point in IWRM, but we still have significant knowledge gaps about the diffuse loads of organic micropollutants (OMP) that leak from both urban and agricultural areas. Most European catchments possess mixed land use, containing rural (natural and agricultural) landscapes and settlements in varying proportions. Thus, a catchment model supporting IWRM must be able to cope with both classes. However, the majority of existing catchment models is dedicated to either rural or urban areas, while the minority capable of simulating both contain overly simplified descriptions for either land use category. We applied a conceptual model that describes all major land use classes for assessing the impacts of climate change, socio-economic development and management alternatives on diffuse OMP loads. We simulated the loads of 12 compounds (agricultural and urban pesticides and urban biocides) with daily resolution at 11 locations in the stream network of a small catchment (46 km2) in Switzerland. The model considers all important diffuse transport pathways separately, but each with a simple empirical process rate. Consequently, some site-specific observations were required to calibrate rate parameters. We assessed uncertainty during both calibration and prediction phases. Predictions indicated that future OMP loads

  20. Sediment transport simulation in an armoured stream

    Science.gov (United States)

    Milhous, Robert T.; Bradley, Jeffrey B.; Loeffler, Cindy L.

    1986-01-01

    Improved methods of calculating bed material stability and transport must be developed for a gravel bed stream having an armoured surface in order to use the HEC-6 model to examine channel change. Good possibilities exist for use of a two layer model based on the Schoklitsch and the Einstein-Brown transport equations. In Einstein-Brown the D35 of the armour is used for stabilities and the D50 of the bed (sub-surface) is used for transport. Data on the armour and sub-surface size distribution needs to be obtained as part of a bed material study in a gravel bed river; a "shovel" sample is not adequate. The Meyer-Peter, Muller equation should not be applied to a gravel bed stream with an armoured surface to estimate the initiation of transport or for calculation of transport at low effective bed shear stress.

  1. Inert blanketing of a hydride bed using typical grade protium

    Energy Technology Data Exchange (ETDEWEB)

    Klein, J.E. [Savannah River National Laboratory, Aiken (United States)

    2015-03-15

    This paper describes the impact of 500 ppm (0.05%) impurities in protium on the absorption rate of a 9.66 kg LaNi{sub 4.25}Al{sub 0.75} (LANA0.75) metal hydride bed. The presence of 500 ppm or less inerts (i.e. non-hydrogen isotopes) can significantly impact hydrogen bed absorption rates. The impact on reducing absorption rates is significantly greater than predicted assuming uniform temperature, pressure, and compositions throughout the bed. Possible explanations are discussed. One possibility considered was the feed gas contained impurity levels higher than 500 ppm. It was shown that a level of 5000 ppm of inerts would have been necessary to fit the experimental result so this possibility wa dismissed. Another possibility is that the impurities in the protium supply reacted with the hydride material and partially poisoned the hydride. If the hydride were poisoned with CO or another impurity, the removal of the over-pressure gas in the bed would not be expected to allow the hydride loading of the bed to continue as the experimental results showed, so this possibility was also dismissed. The last possibility questions the validity of the calculations. It is assumed in all the calculations that the gas phase composition, temperature, and pressure are uniform throughout the bed. These assumptions are less valid for large beds where there can be large temperature, pressure, and composition gradients throughout the bed. Eventually the impact of 0.05% inerts in protium on bed absorption rate is shown and explained in terms of an increase in inert partial pressure as the bed was loaded.

  2. The Spatial Distribution of Bed Sediment on Fluvial System: A Mini Review of the Aceh Meandering River

    Directory of Open Access Journals (Sweden)

    Muhammad Irham

    2016-08-01

    Full Text Available Dynamic interactions of hydrological and geomorphological processes in the fluvial system result in accumulated deposit on the bed because the capacity to carry sediment has been exceeded. The bed load of the Aceh fluvial system is primarily generated by mechanical weathering resulting in boulders, pebbles, and sand, which roll or bounce along the river bed forming temporary deposits as bars on the insides of meander bends, as a result of a loss of transport energy in the system. This dynamic controls the style and range of deposits in the Aceh River. This study focuses on the spatial distribution of bed-load transport of the Aceh River. Understanding the spatial distribution of deposits facilitates the reconstruction of the changes in controlling factors during accumulation of deposits. One of the methods can be done by sieve analysis of sediment, where the method illuminates the distribution of sediment changes associated with channel morphology under different flow regimes. Hence, the purpose of this mini review is to investigate how the sediment along the river meander spatially dispersed. The results demonstrate that channel deposits in the Aceh River are formed from four different type of materials: pebble deposited along upstream left bank; sand located on the upstream, downstream, and along meander belts; and silt and clay located along the cut bank of meander bends. Because of different depositional pattern, the distribution of the sediment along the river can be used as a surrogate to identify bank stability, as well as to predict critical geometry for meander bend initiation

  3. Bed bug deterrence

    Directory of Open Access Journals (Sweden)

    Haynes Kenneth F

    2010-09-01

    Full Text Available Abstract A recent study in BMC Biology has determined that the immature stage of the bed bug (the nymph signals its reproductive status to adult males using pheromones and thus avoids the trauma associated with copulation in this species. The success of this nymphal strategy of deterrence is instructive. Against the background of increasing problems with bed bugs, this research raises the question whether pheromones might be used to control them. See research article http://www.biomedcentral.com/1741-7007/8/121

  4. Load Tracking in Road Transport

    Directory of Open Access Journals (Sweden)

    Rudi Čop

    2002-09-01

    Full Text Available For the first time in history, remole moniloring and safekeepingof the assels is now possible also during road lransporl.These possibililies were enabled by developmelll of !he informaliontechnology during the last decade. Whereas such developmenlcontinues in a planned direction, !he influence of !heimproved and cheaper means of informal ion upon !he transporicompanies could be foreseen.This arlicle includes !he !ales/ guidelines for !ruck and loadmoniloring syslems develop men!. On the basis of lhese guidelines,!he role of users in !he rem ole monitoring syslems developmentis also presenled. In order lo express !heir problemsmore quickly and lo respond wilh grea/er efficiency, if may benecessmy for !hem lo gel basic knowledge aboul lelecommunicalionand informalics.

  5. The Safety of Hospital Beds

    Science.gov (United States)

    Gervais, Pierre; Pooler, Charlotte; Merryweather, Andrew; Doig, Alexa K.; Bloswick, Donald

    2015-01-01

    To explore the safety of the standard and the low hospital bed, we report on a microanalysis of 15 patients’ ability to ingress, move about the bed, and egress. The 15 participants were purposefully selected with various disabilities. Bed conditions were randomized with side rails up or down and one low bed with side rails down. We explored the patients’ use of the side rails, bed height, ability to lift their legs onto the mattress, and ability to turn, egress, and walk back to the chair. The standard bed was too high for some participants, both for ingress and egress. Side rails were used by most participants when entering, turning in bed, and exiting. We recommend that side rails be reconsidered as a means to facilitate in-bed movement, ingress, and egress. Furthermore, single deck height settings for all patients are not optimal. Low beds as a safety measure must be re-evaluated. PMID:28462302

  6. On the entrainment of solid particles from a fluidized bed

    Energy Technology Data Exchange (ETDEWEB)

    Sciazko, M. (Institute of Chemical Processing of Coal, Zabrze (Poland)); Bandrowski, J.; Raczek, J. (Politechnika Slaska, Gliwice (Poland). Inst. of Chemical Engineering and Apparatus Construction)

    1991-04-01

    This paper presents a generalized approach to the phenomenon of entrainment of solids from a fluidized bed. Starting with the discussion of the transport disengaging height (TDH) and of the elutriation of particles above the TDH, one arrives finally at the relationship between the elutriation rate constant, saturation carrying capacity and choking parameters of pneumatic transport. (orig.).

  7. On equivalent roughness of mobile bed at high shear stress

    Czech Academy of Sciences Publication Activity Database

    Matoušek, Václav; Krupička, Jan

    2009-01-01

    Roč. 57, č. 3 (2009), s. 191-199 ISSN 0042-790X R&D Projects: GA ČR GA103/06/0428 Institutional research plan: CEZ:AV0Z20600510 Keywords : bed shear * experiment * hydraulic transport * sediment transport Subject RIV: BK - Fluid Dynamics Impact factor: 1.000, year: 2009

  8. System for the Reduction of Substances in Reject Water from Reed-Bed Sludge Mineralization Plants

    DEFF Research Database (Denmark)

    2004-01-01

    the reject water via recirculation into a mixed reactor and back onto the reed-beds. The mixed rector consists of a container in which sludge (that is typically loaded directly on to reed-beds) is mixed with recirculated reject water from reed-beds. The sludge mixture has a definable hydraulic retention time...... within the container. The solution is then applied to the reed-beds, which dewaters, converts, and partially mineralize the sludge mixture. The reject water from the reed-beds is split where up to100% of the reject water is recirculated back to the mixed reactor and the remaining usually disposed......The invention is a system for the reduction of substances in reject water from reed-bed sludge mineralization plants (also referred to as sludge dewatering reed-beds). The systems utilizes the composition of substances in reject water from reed-beds and that of sludge to reduce substance mass from...

  9. Field testing of absorption bed clogging

    International Nuclear Information System (INIS)

    Aaltomaa, T.; Joy, D.M

    2002-01-01

    On-site wastewater treatment systems throughout North America most commonly use absorption beds to re-introduce treated wastewater from rural properties into the groundwater. With proper design and operating conditions these systems can work well for over 20 years with some reports of over 40 years. However, failure rates as high as 30% for on-site systems are reported and the most common mode of failure is the clogging of the soil absorption system. Research under laboratory settings has been conducted in a number of institutions to demonstrate the key factors leading to failure. These include items such as poor design, excessive hydraulic loading, and high concentrations of wastewater constituents leading to the formation of an excessive biologic layer (the biomat) at the interface of the sand and gravel. Most of these studies have been on simplified systems under accelerated conditions leading to questions about the validity of the results for actual systems. This project was designed to determine the causes of clogging using actual systems so that questions about the effects of simplified testing could be avoided. In this study actual soil absorption systems with ages from 3 to 15 years were studied to determine the proportion of the bed that was 'failed'. Failure was defined as the portion of the bed which had a significant biomat present and ponding water. Measurements were made of the effluent rates, effluent quality, absorption bed characteristics and background soil conditions. The results confirmed the effect of background soils in that fine grain soils showed a much stronger tendency for biomat formation and reached failure sooner. What was of greatest importance was the effect of the wastewater constituents, most particularly BOD, on the expected bed life. With the exception of soil characteristics, BOD had greatest impact on the rate of failure. For normal operating conditions even a modest change in BOD, within the range of expected values, resulted

  10. Bed Prism Spectacles

    Science.gov (United States)

    Ribeiro, Jair Lúcio Prados

    2018-01-01

    We only became aware of the existence of bed prism spectacles when a student brought them to the classroom and asked us about how they work. The device proved to be a fertile source of curiosity among the students, and, to be properly understood, it required us to develop a comparison between reflection in a typical mirror and total internal…

  11. Practice Hospital Bed Safety

    Science.gov (United States)

    ... the mattress end Subscribe: FDA Consumer Health Information "Hospital beds are found in nearly all patient care settings or environments," says Joan Ferlo Todd, RN, a senior nurse-consultant at the Food and Drug Administration’s (FDA) Center for Devices and Radiological Health (CDRH). " ...

  12. THE BASING OF STABILIZATION PARAMETERS OF A FORTIFIED RAILWAY BED

    Directory of Open Access Journals (Sweden)

    V. D. Petrenko

    2014-12-01

    Full Text Available Purpose. The article is devoted to stabilization parameters determination of reinforced railway bed. At the present time, the railway plays the leading role in transport system to ensure the needs of freight and passenger traffic. In modern conditions railway operation concentrates on ensuring the necessary level of track reliability, including the roadbed, this is one of the main elements of road structures. The purpose of this article is the determination of basic parameters of stress-strain state to stabilize the soil subgrade embankment by reinforced materials. Methodology. To achieve this goal the following tasks of researches were solved: the effect of reinforcing layer of geomaterial on deformation properties of soil subgrade in various design of strengthening was investigated, the distributions of stresses in the subgrade were determined, reinforced of geomaterials under state load. Experimental studies to explore the nature of the deformation model subgrade at various degrees of stress were carried out. Findings. The analysis of the results of performed experimental and theoretical studies permitted to do the following conclusions. In conducting researches determined the distribution of stresses in the subgrade reinforced geomaterials under static load. The complex of experimental studies allows exploring the nature of the deformation model subgrade at various degrees of stress. Originality. On the basis of the theoretical studies have been regarded the problem of determining the stress-strain state of subgrade reinforced geomaterials by measuring stresses in its application for step loads. Practical value. The practical value was presented by the results of evaluating the effect of reinforcing way for changing the stress-strain state of subgrade.

  13. Probabilistic estimation of entrainment rate in coarse sediment beds

    Science.gov (United States)

    Bottacin-Busolin, Andrea; Tregnaghi, Matteo; Cecchetto, Martina; Marion, Andrea; Tait, Simon

    2017-04-01

    Many problems in river and coastal engineering depend on sediment transport dynamics induced by turbulent flows over sediment beds. Given the chaotic nature of turbulence and the complex mechanics of granular beds, grain-scale interactions between fluid and sediment are better described using stochastic approaches. A probabilistic model is presented linking entrainment rate to the stochastic properties of the near-bed fluid velocity and the probability distribution of particle elevation. By using a simplified description of the mechanics of grain dislodgement, the distribution of particle waiting time is derived, which is linked to the entrainment rate. The predictive capability of the model and the associated uncertainty are analysed using near-bed flow field and grain motion data obtained from flume experiments at low transport stages. The model predictions are found to be in good agreement with the data. Experimental evidence of distinct entrainment mechanisms is discussed, and flow patterns are identified that cause significant fluctuations in the entrainment rate.

  14. VA National Bed Control System

    Data.gov (United States)

    Department of Veterans Affairs — The VA National Bed Control System records the levels of operating, unavailable and authorized beds at each VAMC, and it tracks requests for changes in these levels....

  15. Bed-To-Wall Heat Transfer in a Supercritical Circulating Fluidised Bed Boiler

    Directory of Open Access Journals (Sweden)

    Błaszczuk Artur

    2014-06-01

    Full Text Available The purpose of this work is to find a correlation for heat transfer to walls in a 1296 t/h supercritical circulating fluidised bed (CFB boiler. The effect of bed-to-wall heat transfer coefficient in a long active heat transfer surface was discussed, excluding the radiation component. Experiments for four different unit loads (i.e. 100% MCR, 80% MCR, 60% MCR and 40% MCR were conducted at a constant excess air ratio and high level of bed pressure (ca. 6 kPa in each test run. The empirical correlation of the heat transfer coefficient in a large-scale CFB boiler was mainly determined by two key operating parameters, suspension density and bed temperature. Furthermore, data processing was used in order to develop empirical correlation ranges between 3.05 to 5.35 m·s-1 for gas superficial velocity, 0.25 to 0.51 for the ratio of the secondary to the primary air, 1028 to 1137K for bed temperature inside the furnace chamber of a commercial CFB boiler, and 1.20 to 553 kg·m-3 for suspension density. The suspension density was specified on the base of pressure measurements inside the boiler’s combustion chamber using pressure sensors. Pressure measurements were collected at the measuring ports situated on the front wall of the combustion chamber. The obtained correlation of the heat transfer coefficient is in agreement with the data obtained from typical industrial CFB boilers.

  16. Input-variable sensitivity assessment for sediment transport relations

    Science.gov (United States)

    Fernández, Roberto; Garcia, Marcelo H.

    2017-09-01

    A methodology to assess input-variable sensitivity for sediment transport relations is presented. The Mean Value First Order Second Moment Method (MVFOSM) is applied to two bed load transport equations showing that it may be used to rank all input variables in terms of how their specific variance affects the overall variance of the sediment transport estimation. In sites where data are scarce or nonexistent, the results obtained may be used to (i) determine what variables would have the largest impact when estimating sediment loads in the absence of field observations and (ii) design field campaigns to specifically measure those variables for which a given transport equation is most sensitive; in sites where data are readily available, the results would allow quantifying the effect that the variance associated with each input variable has on the variance of the sediment transport estimates. An application of the method to two transport relations using data from a tropical mountain river in Costa Rica is implemented to exemplify the potential of the method in places where input data are limited. Results are compared against Monte Carlo simulations to assess the reliability of the method and validate its results. For both of the sediment transport relations used in the sensitivity analysis, accurate knowledge of sediment size was found to have more impact on sediment transport predictions than precise knowledge of other input variables such as channel slope and flow discharge.

  17. Hipertensão arterial e obesidade em motoristas profissionais de transporte de cargas Hipertensión arterial y obesidad en choferes profesionales de transporte de cargas Hypertension and obesity among professional drivers who work transporting loads

    Directory of Open Access Journals (Sweden)

    Luciane Cesira Cavagioni

    2010-01-01

    Full Text Available OBJETIVOS: Verificar a prevalência de hipertensão arterial e obesidade em motoristas profissionais de transporte de carga e associá-la com variáveis estudadas. MÉTODOS: Estudo transversal abragendo amostra de 258 motoristas profissionais de transporte de cargas que trafegavam pela Rodovia BR-116, no trecho paulista Regis Bittencourt. RESULTADOS: Os motoristas eram adultos jovens (37,5±10 anos, 19% tabagistas, 55% referiram ingestão de bebidas alcoólicas, 74% sedentários, 57% usavam medicamentos inibidores do sono, percorriam em média 800 km/dia e dirigiam 10 horas/dia. A prevalência da hipertensão arterial foi de 37%, 46% tinham sobrepeso, 36% obesidade e 58% circunferência abdominal aumentada. A análise de regressão logística indicou que a hipertensão arterial se associou (OD: Odds ratio, IC: intervalo de confiança a 95% com: aumento do índice de massa corporal (OR=1,183 IC 1,065-1,314; glicemia (OR=1,039 IC 1,004-1,076; e hábito de ingerir medicamento para inibir o sono (OR= 0,322 IC 0,129-0,801. CONCLUSÃO: Foi expressiva a presença de hipertensão, sobrepeso e obesidade nesses profissionais.OBJETIVOS: Verificar la prevalencia de hipertensión arterial y obesidad en choferes profesionales de transporte de carga y asociarla con variables estudiadas. MÉTODOS: Estudio transversal abarcando una muestra de 258 choferes profesionales de transporte de carga que circulan por la carretera BR-116, en el trecho Regis Bittencourt, en el estado de Sao Paulo. RESULTADOS: Los choferes eran adultos jóvenes (37,5±10 años, 19% tabaquistas, 55% refirieron ingestión de bebidas alcohólicas, 74% sedentarios, 57% usaban medicamentos inhibidores del sueño; recorrían en promedio 800 km/día y conducían 10 horas/día. La prevalencia de la hipertensión arterial fue de 37%, 46% tenían sobrepeso, 36% obesidad y 58% circunferencia abdominal aumentada. El análisis de regresión logística indicó que la hipertensión arterial se asoció (OD

  18. Nail bed onychomatricoma.

    Science.gov (United States)

    Wang, Lei; Gao, Tianwen; Wang, Gang

    2014-10-01

    Onychomatricoma is a rare tumor originating from the nail matrix, and, in rare conditions, from the ventral aspect of the proximal nailfold. Here we report a rare case of a 51-year-old man presenting with melanonychia mainly involving the distal nail plate. Histopathologic examination showed typical findings of onychomatricoma mainly involving the nail bed, while the nail matrix was largely uninvolved. We also identified fungal infection in a focal area of the distal nail plate. Our findings indicate that onychomatricoma can develop in the surrounding epithelial tissue of the nail unit, including the nail bed, and suggest that fungal infection may represent a secondary phenomenon of onychomatricoma. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  19. Geomechanics of bedded salt

    International Nuclear Information System (INIS)

    Serata, S.; Milnor, S.W.

    1979-01-01

    Creep data from the literature search is reinterpreted by SGI, resulting in a better understanding of the temperature and stress state dependence of the octahedral creep rate and the octahedral shear strength. The concept of a transition strength between the elastic and the plastic states is in agreement with the data. The elastic and rheological properties of salt are described, and a set of constitutive equations is presented. The dependence of material properties on parameters such as temperature is considered. Findings on the permeability of salt are summarized, and the in-situ behavior of openings in bedded salt is described based on extensive engineering experience. A stress measuring system utilizing a finite element computer code is discussed. Geological factors affecting the stability of salt openings are considered, and the Stress Control Technique for designing stable openings in bedded salt formations is explained

  20. Modeling biomass gasification in circulating fluidized beds

    Science.gov (United States)

    Miao, Qi

    In this thesis, the modeling of biomass gasification in circulating fluidized beds was studied. The hydrodynamics of a circulating fluidized bed operating on biomass particles were first investigated, both experimentally and numerically. Then a comprehensive mathematical model was presented to predict the overall performance of a 1.2 MWe biomass gasification and power generation plant. A sensitivity analysis was conducted to test its response to several gasifier operating conditions. The model was validated using the experimental results obtained from the plant and two other circulating fluidized bed biomass gasifiers (CFBBGs). Finally, an ASPEN PLUS simulation model of biomass gasification was presented based on minimization of the Gibbs free energy of the reaction system at chemical equilibrium. Hydrodynamics plays a crucial role in defining the performance of gas-solid circulating fluidized beds (CFBs). A 2-dimensional mathematical model was developed considering the hydrodynamic behavior of CFB gasifiers. In the modeling, the CFB riser was divided into two regions: a dense region at the bottom and a dilute region at the top of the riser. Kunii and Levenspiel (1991)'s model was adopted to express the vertical solids distribution with some other assumptions. Radial distributions of bed voidage were taken into account in the upper zone by using Zhang et al. (1991)'s correlation. For model validation purposes, a cold model CFB was employed, in which sawdust was transported with air as the fluidizing agent. A comprehensive mathematical model was developed to predict the overall performance of a 1.2 MWe biomass gasification and power generation demonstration plant in China. Hydrodynamics as well as chemical reaction kinetics were considered. The fluidized bed riser was divided into two distinct sections: (a) a dense region at the bottom of the bed where biomass undergoes mainly heterogeneous reactions and (b) a dilute region at the top where most of homogeneous

  1. Fluid-dynamic behavior of flaxseed fluidized and spouted bed

    Directory of Open Access Journals (Sweden)

    Elza Brandão Santana

    2017-09-01

    Full Text Available ABSTRACT: Processing of particles in a moving bed, such as a fluidized bed or a spouting bed, is commonly used in the operations of drying, coating, and granulation of particulate systems. This process has applications in the chemical, pharmaceutical and, presently, agronomical industries, especially for seed treatment/coating. This research aimed to analyze the fluid-dynamic behavior of fluidized and spouting beds with different air temperatures and loads of flaxseeds (Linum usitatissimum L., with estimates of the fluid-dynamic parameters correlated to each process. The parameters were compared with the values obtained from classical correlations in the literature, with indications of associated percentages of deviation. Influence of fluid dynamics on the physiological quality of seeds was assessed by germination tests and the germination speed index. An analysis of the results indicated that seed processing was adequate for processing in dynamically active beds; however, temperatures above 50ºC in both beds caused significant reductions in the physiological quality of the seeds. Processing in a fluidized bed presented a smaller reduction of the physiological properties of the flaxseed.

  2. Performance Evaluation of the ISS Water Processor Multifiltration Beds

    Science.gov (United States)

    Bowman, Elizabeth M.; Carter, Layne; Wilson, Mark; Cole, Harold; Orozco, Nicole; Snowdon, Doug

    2012-01-01

    The ISS Water Processor Assembly (WPA) produces potable water from a waste stream containing humidity condensate and urine distillate. The primary treatment process is achieved in the Multifiltration Bed, which includes adsorbent media and ion exchange resin for the removal of dissolved organic and inorganic contaminants. The first Multifiltration Bed was replaced on ISS in July 2010 after initial indication of inorganic breakthrough. This bed was returned to ground in July 2011 for an engineering investigation. The water resident in the bed was analyzed for various parameters to evaluate adsorbent loading, performance of the ion exchange resin, microbial activity, and generation of leachates from the ion exchange resin. Portions of the adsorbent media and ion exchange resin were sampled and subsequently desorbed to identify the primary contaminants removed at various points in the bed. In addition, an unused Multifiltration Bed was evaluated after two years in storage to assess the generation of leachates during storage. This assessment was performed to evaluate the possibility that these leachates are impacting performance of the Catalytic Reactor located downstream of the Multifiltration Bed. The results of these investigations and implications to the operation of the WPA on ISS are documented in this paper.

  3. The role of the hyporheic flow on sediment transport processes : an experimental approach using particle image velocimetry

    Science.gov (United States)

    Rousseau, Gauthier; Sklivaniti, Angeliki; Vito Papa, Daniel; Ancey, Christophe

    2017-04-01

    The study of river dynamics usually considers a turbulent stream on an impervious bed. However, it is known that part of the total discharge takes place through the erodible bed, especially for mountain rivers. This hyporheic flow (or subsurface flow) is likely to play an active role in the stability of the erodible bed. The question then arises: How does the hyporheic flow affect bed stability and thereby bed load transport? Monitoring hyporheic flow under natural conditions remains a key challenge. Laboratory experiments and new measurement techniques shed new light on this problem. Using PIV-LIF method (Particle Image Velocimetry - Laser Induced Fluorescence) we investigate hyporheic flows through erodible beds. The experiment is conducted in a 2-m-long and 6-cm-width flume with 2-mm-diameter glass beads and 4-mm-diameter natural pebbles under turbulent stream conditions. In parallel, we develop a simple analytical model that accounts for the interaction between the surface and subsurface flows at the bed interface. As the Reynolds number of the hyporheic flow is fairly high (10 to 100), inertia cannot be neglected. This leads us to use the Darcy-Forchheimer law instead of Darcy's law to model hyporheic flows. We show that this model is consistent with the PIV-LIF experimental results. Moreover, the PIV-LIF data show that hyporheic flows modify the velocity profile and turbulence. Our measurements and empirical model emphasize the exchange processes in coarse-grained river for incipient sediment motion.

  4. Celebrating 40 years anaerobic sludge bed reactors for industrial wastewater treatment

    NARCIS (Netherlands)

    Van Lier, J.B.; Van der Zee, F.P.; Frijters, C.T.M.J.; Ersahin, M.E.

    2015-01-01

    In the last 40 years, anaerobic sludge bed reactor technology evolved from localized lab-scale trials to worldwide successful implementations at a variety of industries. High-rate sludge bed reactors are characterized by a very small foot print and high applicable volumetric loading rates. Best

  5. Understanding and predicting bed humidity in fluidized bed granulation.

    Science.gov (United States)

    Hu, Xinhui; Cunningham, John; Winstead, Denita

    2008-04-01

    Bed humidity is a critical parameter that needs to be controlled in a fluidized bed granulation to ensure reliability. To predict and control the bed humidity during the fluidized bed granulation process, a simple model based on the mass conservation of moisture was developed. The moisture mass balance model quantitatively simulates the effects of spray rate, binder solution concentration, airflow rate, inlet air temperature, and dew point on the bed humidity. The model was validated by a series of granulations performed in different scale granulators including Glatt GPCG-1, GPCG-15, and GPCG-60. Good agreement was observed between the theoretical prediction and the measured loss on drying (LOD). The model developed in the current work enables us to choose the appropriate parameters for the fluidized bed granulation and can be used as a valuable tool in process scaling-up. 2007 Wiley-Liss, Inc

  6. Coal Bed Methane Primer

    Energy Technology Data Exchange (ETDEWEB)

    Dan Arthur; Bruce Langhus; Jon Seekins

    2005-05-25

    During the second half of the 1990's Coal Bed Methane (CBM) production increased dramatically nationwide to represent a significant new source of income and natural gas for many independent and established producers. Matching these soaring production rates during this period was a heightened public awareness of environmental concerns. These concerns left unexplained and under-addressed have created a significant growth in public involvement generating literally thousands of unfocused project comments for various regional NEPA efforts resulting in the delayed development of public and fee lands. The accelerating interest in CBM development coupled to the growth in public involvement has prompted the conceptualization of this project for the development of a CBM Primer. The Primer is designed to serve as a summary document, which introduces and encapsulates information pertinent to the development of Coal Bed Methane (CBM), including focused discussions of coal deposits, methane as a natural formed gas, split mineral estates, development techniques, operational issues, producing methods, applicable regulatory frameworks, land and resource management, mitigation measures, preparation of project plans, data availability, Indian Trust issues and relevant environmental technologies. An important aspect of gaining access to federal, state, tribal, or fee lands involves education of a broad array of stakeholders, including land and mineral owners, regulators, conservationists, tribal governments, special interest groups, and numerous others that could be impacted by the development of coal bed methane. Perhaps the most crucial aspect of successfully developing CBM resources is stakeholder education. Currently, an inconsistent picture of CBM exists. There is a significant lack of understanding on the parts of nearly all stakeholders, including industry, government, special interest groups, and land owners. It is envisioned the Primer would being used by a variety of

  7. Bed Rest Muscular Atrophy

    Science.gov (United States)

    Greenleaf, John E.

    2000-01-01

    A major debilitating response from prolonged bed rest (BR) is muscle atrophy, defined as a "decrease in size of a part of tissue after full development has been attained: a wasting away of tissue as from disuse, old age, injury or disease". Part of the complicated mechanism for the dizziness, increased body instability, and exaggerated gait in patients who arise immediately after BR may be a result of not only foot pain, but also of muscular atrophy and associated reduction in lower limb strength. Also, there seems to be a close association between muscle atrophy and bone atrophy. A discussion of many facets of the total BR homeostatic syndrome has been published. The old adage that use determines form which promotes function of bone (Wolff's law) also applies to those people exposed to prolonged BR (without exercise training) in whom muscle atrophy is a consistent finding. An extreme case involved a 16-year-old boy who was ordered to bed by his mother in 1932: after 50 years in bed he had "a lily-white frame with limbs as thin as the legs of a ladder-back chair". These findings emphasize the close relationship between muscle atrophy and bone atrophy. In addition to loss of muscle mass during deconditioning, there is a significant loss of muscle strength and a decrease in protein synthesis. Because the decreases in force (strength) are proportionately greater than those in fiber size or muscle cross-sectional area, other contributory factors must be involved; muscle fiber dehydration may be important.

  8. Evaluation of Effect of Fuel Assembly Loading Patterns on Thermal and Shielding Performance of a Spent Fuel Storage/Transportation Cask

    Energy Technology Data Exchange (ETDEWEB)

    Cuta, Judith M.; Jenquin, Urban P.; McKinnon, Mikal A.

    2001-11-20

    The licensing of spent fuel storage casks is generally based on conservative analyses that assume a storage system being uniformly loaded with design basis fuel. The design basis fuel typically assumes a maximum assembly enrichment, maximum burn up, and minimum cooling time. These conditions set the maximum decay heat loads and radioactive source terms for the design. Recognizing that reactor spent fuel pools hold spent fuel with an array of initial enrichments, burners, and cooling times, this study was performed to evaluate the effect of load pattern on peak cladding temperature and cask surface dose rate. Based on the analysis, the authors concluded that load patterns could be used to reduce peak cladding temperatures in a cask without adversely impacting the surface dose rates.

  9. Experimental evaluation of a novel robotic hospital bed mover with omni-directional mobility.

    Science.gov (United States)

    Guo, Zhao; Yee, Rachael Bei; Mun, Kyung-Ryoul; Yu, Haoyong

    2017-11-01

    Bed pushing during patient transfer is one of the most physically demanding and yet common tasks in the hospital setting. Powered bed movers have been increasingly introduced to hospitals to reduce physiological strains on the users. This study introduces and quantifies the manpower efficiency and health benefits of a novel robotic-assisted omni-directional hospital bed transporter (SESTO Bed Mover) in comparison with a conventional manual transport stretcher (Stryker Trauma Stretcher 1037) and a powered transport stretcher (HOSPIMEK HMPT 740), which has a fifth powered wheel providing power assistance only in the forward direction. A total of 14 subjects were recruited (7 porters and 7 students) and were tasked to complete a course within a controlled lab environment. It is concluded that the robotic bed mover is able to halve the required manpower to push hospital beds as compared to conventional bed pushing without any additional physiological strain, potentially improving efficiency by two-fold. Electromyography (EMG) patterns showed that users relied on the shoulder and back muscles in a fashion similar to conventional pushing, further confirming the intuitive drive of the robotic bed mover. Overall, the robotic bed mover shows reduced physical demands, less manpower required for patient transport and reduced back muscle activities, which strongly suggest health benefits for workers in the hospital. Copyright © 2017 Elsevier Ltd. All rights reserved.

  10. Particle bed reactor modeling

    Science.gov (United States)

    Sapyta, Joe; Reid, Hank; Walton, Lew

    The topics are presented in viewgraph form and include the following: particle bed reactor (PBR) core cross section; PBR bleed cycle; fuel and moderator flow paths; PBR modeling requirements; characteristics of PBR and nuclear thermal propulsion (NTP) modeling; challenges for PBR and NTP modeling; thermal hydraulic computer codes; capabilities for PBR/reactor application; thermal/hydralic codes; limitations; physical correlations; comparison of predicted friction factor and experimental data; frit pressure drop testing; cold frit mask factor; decay heat flow rate; startup transient simulation; and philosophy of systems modeling.

  11. Feasibility Study of a Lunar Analog Bed Rest Model

    Science.gov (United States)

    Cromwell, Ronita L.; Platts, Steven H.; Yarbough, Patrice; Buccello-Stout, Regina

    2010-01-01

    The purpose of this study was to determine the feasibility of using a 9.5deg head-up tilt bed rest model to simulate the effects of the 1/6 g load to the human body that exists on the lunar surface. The lunar analog bed rest model utilized a modified hospital bed. The modifications included mounting the mattress on a sled that rolled on bearings to provide freedom of movement. The weight of the sled was off-loaded using a counterweight system to insure that 1/6 body weight was applied along the long axis (z-axis) of the body. Force was verified through use of a force plate mounted at the foot of the bed. A seating assembly was added to the bed to permit periods of sitting. Subjects alternated between standing and sitting positions throughout the day. A total of 35% of the day was spent in the standing position and 65% was spent sitting. In an effort to achieve physiologic fluid shifts expected for a 1/6 G environment, subjects wore compression stockings and performed unloaded foot and ankle exercises. Eight subjects (3 females and 5 males) participated in this study. Subjects spent 13 days in the pre-bed rest phase, 6 days in bed rest and 3 days post bed rest. Subjects consumed a standardized diet throughout the study. To determine feasibility, measures of subject comfort, force and plasma volume were collected. Subject comfort was assessed using a Likert scale. Subjects were asked to assess level of comfort (0-100) for 11 body regions and provide an overall rating. Results indicated minimal to no discomfort as most subjects reported scores of zero. Force measures were performed for each standing position and were validated against subject s calculated 1/6 body weight (r(sup 2) = 0.993). The carbon monoxide rebreathing technique was used to assess plasma volume during pre-bed rest and on the last day of bed rest. Plasma volume results indicated a significant decrease (p = 0.001) from pre to post bed rest values. Subjects lost on average 8.3% (sd = 6.1%) during the

  12. Load Measurements

    DEFF Research Database (Denmark)

    Kock, Carsten Weber; Vesth, Allan

    The report describes Load measurements carried out on a given wind turbine. The aim of the measurement program regarding the loads on the turbine is to verify the basic characteristics of the wind turbine and loads on the blades, the rotor and the tower, using [Ref 1], [Ref2] and [Ref 3]. Regarding...... the fatigue loads, the rotor, blades and tower moments are presented. The fatigue loads are evaluated using rainflow counting described in detail in Ref. [1]. The 1Hz equivalent load ranges are calculated at different wind speeds. All information regarding the instrumentation is collected in [ref 4] and [ref...

  13. Predicting Bed Mobility in a Simple River Channel

    Science.gov (United States)

    Wydzga, M. A.; Legleiter, C.; Dunne, T.

    2007-12-01

    Prediction of the frequency and spatial pattern of bed mobility in gravel bed rivers is central to a wide range of theoretical and applied interests ranging from sediment transport to the impacts of natural or managed floods on aquatic organisms. Although bed mobility has been investigated in numerous flume and field studies, accurate predictions of grain entrainment and transport in gravel bed rivers remain elusive. Alluvial rivers typically encompass a much wider range of hydraulic and sedimentological conditions than those that have been recreated in laboratory flume studies upon which many grain entrainment and transport models are based. These flume studies are limited to the examination of processes occurring over the short term, commonly with the absence of slower processes such as fine-grain infilling. On the other hand, in field studies key variables can not be controlled and the spatial complexity of processes and conditions complicate data collection and analysis. A unique opportunity currently exists to help bridge this gap between laboratory and field studies: a 3.2 km long, recently constructed, single thread, alternate bar, gravel bed river channel of the Merced River. This channel, constructed for ecosystem restoration purposes, is slowly developing greater complexity, but is still currently defined by a simple plan form and cross-sectional channel geometry compared to most natural gravel bed river channels. This channel can thus be considered a full-scale flume. In the six years since the channel was constructed, a wider range of sedimentological bed conditions have evolved than have been created in a laboratory flume. We are characterizing the bed grain sizes, flow field, grain entrainment, and the sedimentological or bed state conditions in this simple channel. The flow field is modeled using a calibrated, 2D hydrodynamic flow model, MD_SWMS. Grain entrainment is measured with both metal tags inserted into the bed, and painted rock tracers

  14. Prediction of bed level variations in nonuniform sediment bed channel

    Indian Academy of Sciences (India)

    B R Andharia

    2018-04-12

    Apr 12, 2018 ... have been undertaken for measurements of bed and water levels in an aggrading channel due to overloading of nonuniform sediments ..... 2.4 Thickness of active bed layer. The mixing zone of sediment remaining in contact with the flow is referred as active layer (ABL). The thickness and particle size ...

  15. Combustion of peanut shells in a cone-shaped bubbling fluidized-bed combustor using alumina as the bed material

    International Nuclear Information System (INIS)

    Arromdee, Porametr; Kuprianov, Vladimir I.

    2012-01-01

    Highlights: ► We propose burning of peanut shells in a conical fluidized bed using alumina sand. ► We examine hydrodynamic, combustion and emission characteristics of the reactor. ► High, over 99%, combustion efficiency is achievable. ► Emissions of CO and NO from the combustor meet the national emission limits. ► Composition of the bed material undergoes significant changes during the combustion. -- Abstract: This paper reports experimental studies on burning peanut shells in the conical fluidized-bed combustor using alumina sand as the fluidizing agent. Prior to combustion tests, hydrodynamic regimes and characteristics of a conical alumina–biomass bed were investigated under cold-state conditions for variable percentage of peanut shells in the mixture and static bed height. With selected particle sizes (300–500 μm) and static bed height (30 cm), alumina ensured bubbling fluidization regime of the bed at operating conditions specified for firing biomass. Combustion tests were performed at 60 kg/h and 45 kg/h fuel feed rates, while ranging excess air from 20% to 80% at a fixed combustor load. Temperature and gas concentrations (O 2 , CO, C x H y as CH 4 , and NO) were measured along radial and axial directions inside the reactor as well as at stack in order to characterize combustion and emission performance of the combustor for the ranges of operating conditions. For firing 60 kg/h peanut shells, excess air of 40% can be selected as an appropriate value ensuring high, about 99%, combustion efficiency and rather low emissions of CO and NO: 520 ppm and 125 ppm, respectively (both on a dry basis and at 6% O 2 ). With reducing combustor load, the combustion efficiency and emission characteristics were improved to a little extent. No evidence of bed agglomeration was found during 30-h combustion tests on this conical fluidized-bed combustor using alumina sand as the bed material. However, the timescale effect on the composition of the bed material was

  16. Load and resistance factor design calibration to determine a resistance factor for the modification of the Kansas Department of Transportation-Engineering News Record formula.

    Science.gov (United States)

    2014-02-01

    This report contains the results of a study describing the development of resistance factors for use : with the Kansas Department of Transportation (KDOT) Engineering News Record (ENR) formula for driven : piles. KDOT has verified driven pile resista...

  17. Numerical investigation of bed morphodynamics due to a hydrokinetic turbine

    Science.gov (United States)

    Yang, X.; Khosronejad, A.; Sotiropoulos, F.

    2013-12-01

    Marine and hydrokinetic (MHK) energy comprises an important source of clean and renewable energy. The beds of natural waterways are usually erodible. The hydrokinetic turbines affect the sediment transport, which, on the other hand, also influences the performance of hydrokinetic turbines. A powerful computational framework for simulating marine and hydrokinetic (MHK) turbine arrays mounted in complex river bathymetry with sediment transport has been developed and validated by our group. In this work we apply this method to simulate the turbulent flow over a hydrokinetic turbine mounted in an open channel with erodible bed. Preliminary results show qualitatively good agreement with the experiment. Detailed comparison with measurements and analysis of the simulation results will be presented in the conference. Contours of the instantaneous streamwise velocity for flow past a hydrokinetic turbine mounted on an erodible bed.

  18. The impact of structural development on near bed flow dynamics in gravel bed rivers: coupling flume experiments with numerical modelling

    Science.gov (United States)

    Ockelford, A.; Hardy, R. J.; Rice, S. P.; Powell, M.

    2017-12-01

    It is increasingly being recognised that gravel bed rivers develop a surface `texture' in response to changes in the flow and sediment regime. This textural response often takes the form of a bed structure which develops to ultimately stabilise the surface across a range of spatio-temporal scales and it is these topographical structures which determine the flow structures that develop over the river bed. However, our ability to measure and parameterise that structure in ways that are useful and meaningful for the prediction of flow dynamics, still remains inadequate; this paper uses a three dimensional numerical model to assess how the temporal development of structure influences the near bed flow dynamics. Using a suite of flume based experiments a unimodal grain size distribution (σg = 1.30, D50 = 8.8mm) was exposed to three different levels of constant bed shear that produced sediment transport conditions ranging from marginal transport to conditions approaching full mobility of all size fractions. Surface structuring characteristics were measured at a high spatio-temporal resolution such that the time evolution of the beds could be fully described. In total 54 surfaces were generated and run through a Reynolds averaged three dimensional numerical model with an Rng turbulence closure. The topography input included using an immersed boundary technique within a Cartesian framework. Discussion concentrates on the how the trajectory of structural evolution under the different treatments affects the near bed flow dynamics. Specifically links are made between how the scales of boundary topography influence the flow and discusses how the measured flow variability at any one point will contain both locally derived and upstream-inherited flow structures, according to the range of scales of bed topography present. Keywords: Graded, Sediment, Structure, Turbulence, Modelling

  19. The state of development of multilayer sand bed filters

    International Nuclear Information System (INIS)

    Jordan, S.; Schikarski, W.

    1977-01-01

    The state of development of multilayer sand bed filters may be described as follows: 1) Sand bed filters are generally suitable for the filtration of aggressive aerosols, in particular in cases of additional thermal loads, pressure peaks (fire safety, earthquakes). 2) Sand bed filters permit high flow rates, GfK filters (GfK = Gesellschaft fuer Kernforschung) reach 10 m 3 /min x m 2 with charges of more than 1 kg/m 2 and a separating efficiency > 99%. (use as pre-filters for the separation of large amounts of aerosols). 3) With proper optimization, the separating efficiency is better than that of class S filters (99.97%), while no significant reduction of the charge is required. 4) Exchange of sand bed filters is possible with a suitable vertical arrangement of the sand layers. 5) Sand bed filters may be combined with class S filters. The experience so far with sand bed filters was gained on the basis of experiments with aerosols from metal combustion. (orig./HP) [de

  20. REMOVING AGGRESSIVE CARBON DIOXIDE FROM WATER USING MELAPHYRE BED

    Directory of Open Access Journals (Sweden)

    Magdalena Maria Michel

    2017-09-01

    Full Text Available The experiment was based on filtration of the highly aggressive water through the melaphyre bed. The quartz bed was non-reactive reference material. The aim of this work was to determine the ability of the melaphyre to remove aggressive CO2 during the chemical reaction. It was noted that a decrease of acidity of the filtrate in comparison to the feed and an increase of its alkalinity and pH. It was calculated that until the moment of exhaustion of the de-acidifying properties of the melaphyre, maximum amount of bound CO2 added to the water was 29.7 g CO2/L of the bed, and maximum amount of the aggressive CO2 removed from the water was 33.3 g CO2/L of the bed. Regarding very high content of the aggressive CO2 (116 mg/L average in the feed only 28.76% of this component was subject to transformation into bound and affiliated CO2 in the filtrate. For the melaphyre bed the CO2 loss from the experiment system following from desorption was 7.80% of the total load of CO2 added with the feed. On the quartz bed the loss was slightly lower 4.56%.

  1. Sediment Transport On The Vegetated Bank of The Soil Bioengineering Test Flume At The Wien River

    Science.gov (United States)

    Meixner, H.; Rauch, H. P.; Schreiber, J.; Vollsinger, St.

    Soil bioengineering structures are frequently used to protect river banks. Studies by WEITZER / DOPPLER / FLORINETH (1998) on measuring the pull-out resistance and by OPLATKA (1998) on the effective flow acting on willows show that a high hydraulic load by itself does not lead to failure or dislodging of the plants but that the slopeSs instability is caused by the erosion of bed material. The onset of erosion is indicated by a critical shear stress, determined by the combination of a number of factors such as flow velocity, lift force, turbulence, grain size, grain shape, stratifica- tion of the river bed material and the type and density of the vegetation. Investigations into the stability of a variety of soil bioengineering structures (brush mattress with wil- lows, branch layers, fascine layers) are carried out at the soil bioengineering test flume along the Wien river, where artificial flooding runs expose the plant/soil complex to extreme hydraulic loads. Marked, surveyed and weighed gravel material of different grain diameters (10, 20, 40, 60, 80 and 100 mm) and variable layer arrangements is put into the bed or bank of the test flume to determine the critical shear stress. The exact grain position is identified before and after each artificial flooding, so that the mean sediment transport path can be determined for each grain diameter. By comparing sed- iment transport paths for different grain sizes, a critical grain diameter can be defined for each soil bioengineering structure. The critical grain diameter thus obtained is used as an input parameter in calculating the critical shear stress from bed load transport equations. Based on the data thus collected and their analysis it is possible to present and interpret initial findings.

  2. Reconstructing the transport history of pebbles on Mars

    Science.gov (United States)

    Szabó, Tímea; Domokos, Gábor; Grotzinger, John P.; Jerolmack, Douglas J.

    2015-01-01

    The discovery of remarkably rounded pebbles by the rover Curiosity, within an exhumed alluvial fan complex in Gale Crater, presents some of the most compelling evidence yet for sustained fluvial activity on Mars. While rounding is known to result from abrasion by inter-particle collisions, geologic interpretations of sediment shape have been qualitative. Here we show how quantitative information on the transport distance of river pebbles can be extracted from their shape alone, using a combination of theory, laboratory experiments and terrestrial field data. We determine that the Martian basalt pebbles have been carried tens of kilometres from their source, by bed-load transport on an alluvial fan. In contrast, angular clasts strewn about the surface of the Curiosity traverse are indicative of later emplacement by rock fragmentation processes. The proposed method for decoding transport history from particle shape provides a new tool for terrestrial and planetary sedimentology. PMID:26460507

  3. Effectiveness of Bed Bug Pesticides

    Science.gov (United States)

    Before EPA allows a bed bug claim on a label, the product must be supported by data showing it will kill bed bugs when applied according to the label. Also consider factors such as extent of infestation, site preparation, and insect life stages.

  4. Turning patients over in bed

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/patientinstructions/000426.htm Turning patients over in bed To use the sharing features on this page, ... Patient The following steps should be followed when turning a patient: If you can, raise the bed to a level that reduces back strain for ...

  5. Novel instrumentation to detect sliding and erratic bed load motion

    CSIR Research Space (South Africa)

    Ilgner, HJ

    2014-09-01

    Full Text Available and processed online. Tests were conducted at different test facilities with metallic pipes providing internal diameters ranging from 40 to 150 mm, and with various pipe wall thicknesses between 2 and 18 mm. While the clamp-on sensors were able to detect...

  6. On the use of horizontal acoustic doppler profilers for continuous bed shear stress monitoring

    NARCIS (Netherlands)

    Vermeulen, B.; Hoitink, A.J.F.; Sassi, M.G.

    2013-01-01

    Continuous monitoring of bed shear stress in large river systems may serve to better estimate alluvial sediment transport to the coastal ocean. Here we explore the possibility of using a horizontally deployed acoustic Doppler current profiler (ADCP) to monitor bed shear stress, applying a prescribed

  7. Gas-particle interactions in dense gas-fluidised beds

    NARCIS (Netherlands)

    Li, J.; Kuipers, J.A.M.

    2003-01-01

    The occurrence of heterogeneous flow structures in gas-particle flows seriously affects gas¿solid contacting and transport processes in dense gas-fluidized beds. A computational study, using a discrete particle method based on Molecular Dynamics techniques, has been carried out to explore the

  8. Propylene polymerization in a circulating slugging fluidized bed reactor

    NARCIS (Netherlands)

    van Putten, I.C.

    2004-01-01

    The work presented in this thesis is concerned with research on the riser of a circulating fluidized bed system for olefin polymerization. In the riser section, fluidization takes place in the transporting slugging mode and polymer particles are produced in the riser in a non-isothermal way.

  9. High resolution field study of sediment dynamics on a strongly heterogeneous bed

    Science.gov (United States)

    Bailly Du Bois, P.; Blanpain, O.; Lafite, R.; Cugier, P.; Lunven, M.

    2010-12-01

    Extensive field measurements have been carried out at several stations in a macrotidal inner continental shelf in the English Channel (around 25 m depth) during spring tide period. The strong tidal current measured (up to 1.6 m.s-1) allowed sediment dynamics on a bed characterised by a mixture of size with coarse grains to be dominant. Data acquired in such hydro-sedimentary conditions are scarce. A new instrument, the DYnamic Sediment Profile Imagery (DySPI) system, was specifically conceived and implemented in-situ to observe and measure, with a high temporal resolution, the dynamics of a strongly heterogeneous mixture of particles in a grain-size scale. The data collected covered: 1) grain size range (side scan sonar, video observations, Shipeck grab samples, DySPI images) and vertical sorting (stratigraphic sampling by divers) of sediment cover, 2) hydrodynamic features (acoustic Doppler velocimeter, acoustic Doppler profiler), 3) suspended load nature and dynamics (optical backscatter, chlorophyll fluorometer, particle size analyser, Niskin bottles, scanning electron microscopy), 4) sand and gravel bedload transport estimates (DySPI image processing), 5) transfer dynamics of fine grains within a coarse matrix and their depth of penetration (radionuclides measurements in stratigraphic samples). The four stations present different grain size vertical sorting from a quasi-permanent armouring to a homogenous distribution. The sediment cover condition is directly linked to hydrodynamic capacity and sediment availability. Fine grain ratio within deep sediment layers (up to 10 cm) is higher when the bed armouring is durable. However, fine sediments are not permanently depth trapped: deep layers are composed of few years-old radionuclide tracers fixed on fine grains and a vertical mixing coefficient has been evaluated for each sediment cover. Fine grain dynamics within a coarse matrix is inversely proportional to the robustness of the armour layer. For current

  10. Neutronic modeling of pebble bed reactors in APOLLO2

    International Nuclear Information System (INIS)

    Grimod, M.

    2010-01-01

    In this thesis we develop a new iterative homogenization technique for pebble bed reactors, based on a 'macro-stochastic' transport approximation in the collision probability method. A model has been developed to deal with the stochastic distribution of pebbles with different burnup in the core, considering spectral differences in homogenization and depletion calculations. This is generally not done in the codes presently used for pebble bed analyses, where a pebble with average isotopic composition is considered to perform the cell calculation. Also an iterative core calculation scheme has been set up, where the low-order RZ S N full-core calculation computes the entering currents in the spectrum zones subdividing the core. These currents, together with the core k eff , are then used as surface source in the fine-group heterogeneous calculation of the multi-pebble geometries. The developed method has been verified using reference Monte Carlo simulations of a simplified PBMR- 400 model. The pebbles in this model are individually positioned and have different randomly assigned burnup values. The APOLLO2 developed method matches the reference core k eff within ± 100 pcm, with relative differences on the production shape factors within ± 4%, and maximum discrepancy of 3% at the hotspot. Moreover, the first criticality experiment of the HTR-10 reactor was used to perform a first validation of the developed model. The computed critical number of pebbles to be loaded in the core is very close to the experimental value of 16890, only 77 pebbles less. A method to calculate the equilibrium reactor state was also developed and applied to analyze the simplified PBMR-400 model loaded with different fuel types (UO 2 , Pu, Pu + MA). The potential of the APOLLO2 method to compute different fluxes for the different pebble types of a multi-pebble geometry was used to evaluate the bias committed by the average composition pebble approximation. Thanks to a 'compensation of error

  11. Effects of bed-load movement on flow resistance over bed forms

    Indian Academy of Sciences (India)

    Tehran, Iran. 2Department of Irrigation and Reclamation Engineering, Soil and Water Faculty,. University of Tehran, Tehran, Iran ... Steady flow of clear as against sediment-laden water with different flow depths and velocities were studied in the ..... McGraw-Hill Series In: Water Resource and Envi- ronmental Engineering.

  12. Effects of bed-load movement on flow resistance over bed forms

    Indian Academy of Sciences (India)

    1. Department of Irrigation and Reclamation Engineering, University of Tehran, Tehran, Iran; Department of Irrigation and Reclamation Engineering, Soil and Water Faculty, University of Tehran, Tehran, Iran ...

  13. Multiscale Analysis of Pebble Bed Reactors

    Energy Technology Data Exchange (ETDEWEB)

    Hans Gougar; Woo Yoon; Abderrafi Ougouag

    2010-10-01

    – The PEBBED code was developed at the Idaho National Laboratory for design and analysis of pebble-bed high temperature reactors. The diffusion-depletion-pebble-mixing algorithm of the original PEBBED code was enhanced through coupling with the THERMIX-KONVEK code for thermal fluid analysis and by the COMBINE code for online cross section generation. The COMBINE code solves the B-1 or B-3 approximations to the transport equation for neutron slowing down and resonance interactions in a homogeneous medium with simple corrections for shadowing and thermal self-shielding. The number densities of materials within specified regions of the core are averaged and transferred to COMBINE from PEBBED for updating during the burnup iteration. The simple treatment of self-shielding in previous versions of COMBINE led to inaccurate results for cross sections and unsatisfactory core performance calculations. A new version of COMBINE has been developed that treats all levels of heterogeneity using the 1D transport code ANISN. In a 3-stage calculation, slowing down is performed in 167 groups for each homogeneous subregion (kernel, particle layers, graphite shell, control rod absorber annulus, etc.) Particles in a local average pebble are homogenized using ANISN then passed to the next (pebble) stage. A 1D transport solution is again performed over the pebble geometry and the homogenized pebble cross sections are passed to a 1-d radial model of a wedge of the pebble bed core. This wedge may also include homogeneous reflector regions and a control rod region composed of annuli of different absorbing regions. Radial leakage effects are therefore captured with discrete ordinates transport while axial and azimuthal effects are captured with a transverse buckling term. In this paper, results of various PBR models will be compared with comparable models from literature. Performance of the code will be assessed.

  14. Load and resistance factor design calibration to determine a resistance factor for the modification of the Kansas Department of Transportation-Engineering News Record formula : [technical summary].

    Science.gov (United States)

    2014-02-01

    The Kansas Department of Transportation (KDOT) has, in recent years, used a : variation of the Engineering News Record (ENR) formula to determine the capacity of : piles in the field. It was a concern that the KDOT-ENR formula was under-predicting : ...

  15. Transport of microplastics in coastal seas

    Science.gov (United States)

    Zhang, Hua

    2017-12-01

    Microplastic pollution of the marine environment has received increasing attention from scientists, the public, and policy makers over the last few years. Marine microplastics predominantly originate near the coast and can remain in the nearshore zone for some time. However, at present, there is little understanding of the fate and transport of microplastics in coastal regions. This paper provides a comprehensive overview of the physical processes involved in the movement of microplastics from estuaries to the continental shelf. The trajectory and speed of microplastics are controlled by their physical characteristics (density, size, and shape) and ocean dynamic conditions (wind, waves, tides, thermohaline gradients, and the influence of benthic sediments). Microplastic particles can be subjected to beaching, surface drifting, vertical mixing, and biofouling, as well as bed-load and suspended load transport processes, until reaching terminal deposition on beaches, in coastal marshes, in benthic sediments or until they are carried by ocean currents to subtropical convergence zones. The dynamic interaction of released microplastics with the shoreline is regulated by onshore/offshore transport, which is impacted by the source location as well as the geometry, vegetation, tidal regime, and wave direction. Wind and wave conditions dominate surface drifting of buoyant particles through Ekman drift, windage, and Stokes drift mechanisms. Neustic microplastic particles travel in the subsurface because of vertical mixing through wind-driven Langmuir circulation and heat cycling. Increasing accumulation of microplastics in benthic sediments needs to be quantitatively explored in terms of biofouling, deposition, entrainment, and transport dynamics. Further studies are required to understand the following: 1) the primary parameters (e.g., windage, terminal velocity, diffusivity, critical shear stress) that determine microplastic transport in different pathways; 2) dynamic

  16. Next generation network based carrier ethernet test bed for IPTV traffic

    DEFF Research Database (Denmark)

    Fu, Rong; Berger, Michael Stübert; Zheng, Yu

    2009-01-01

    This paper presents a Carrier Ethernet (CE) test bed based on the Next Generation Network (NGN) framework. After the concept of CE carried out by Metro Ethernet Forum (MEF), the carrier-grade Ethernet are obtaining more and more interests and being investigated as the low cost and high performanc...... services of transport network to carry the IPTV traffic. This test bed is approaching to support the research on providing a high performance carrier-grade Ethernet transport network for IPTV traffic....

  17. Load forecasting

    International Nuclear Information System (INIS)

    Mak, H.

    1995-01-01

    Slides used in a presentation at The Power of Change Conference in Vancouver, BC in April 1995 about the changing needs for load forecasting were presented. Technological innovations and population increase were said to be the prime driving forces behind the changing needs in load forecasting. Structural changes, market place changes, electricity supply planning changes, and changes in planning objectives were other factors discussed. It was concluded that load forecasting was a form of information gathering, that provided important market intelligence

  18. Transport and concentration controls for chloride, strontium, potassium and lead in Uvas Creek, a small cobble-bed stream in Santa Clara County, California, U.S.A. 1. Conceptual model

    Science.gov (United States)

    Kennedy, V.C.; Jackman, A.P.; Zand, S.M.; Zellweger, G.W.; Avanzino, R.J.

    1984-01-01

    Stream sediments adsorb certain solutes from streams, thereby significantly changing the solute composition; but little is known about the details and rates of these adsorptive processes. To investigate such processes, a 24-hr. injection of a solution containing chloride, strontium, potassium, sodium and lead was made at the head of a 640-m reach of Uvas Creek in west-central Santa Clara County, California. Uvas Creek is a cobble-bed pool-and-riffle stream draining the eastern slopes of the Santa Cruz Mountains. By September 12, 1973, after a long dry season, Uvas Creek had a low (0.0215 m3s-1 average) flow which varied diurnally, from 0.018 to 0.025 m3s-1. Because stream discharge varied while the injection rate was constant, the concentration of tracers (injected solutes), after mixing in the stream, varied inversely with discharge. Chloride, a nonreactive solute, served as a tracer of water movement. Analysis of extensive chloride concentration data at five sites below the injection point during and after the injection demonstrated that there was considerable underflow of water through the stream gravels; however, the extent of underflow varied greatly within the study reach. Pre-injection water, displaced by tracer-laden water percolating through the gravels, diluted tracers in the stream channel, giving the mistaken impression of groundwater inflow at some points. Accurate measurement of total discharge in such streams requires prolonged tracer injection unless a reach can be found where underflow is negligible. Strontium and potassium were adsorbed by the bed sediments to a moderate extent and lead was strongly adsorbed. A high proportion of these metals could be removed by adsorption from percolating underflow because of extensive and intimate contact with bed sediments. After channel clearing following injection cutoff, 51% of the added strontium and 96% of the lead remained in the study reach, whereas only 19% of the chloride remained. Packets of sized

  19. Torsion testing of bed joints

    DEFF Research Database (Denmark)

    Hansen, Klavs Feilberg; Pedersen, Carsten Mørk

    2008-01-01

    be carried out directly in a normal testing machine. The torsion strength is believed to be the most important parameter in out-of-plane resistance of masonry walls subjected to bending about an axis perpendicular to the bed joints. The paper also contains a few test results from bending of small walls about...... an axis perpendicular to the bed joints, which indicate the close connection between these results and results from torsion tests. These characteristics make the torsion strength well suited to act as substitute parameter for the bending strength of masonry about an axis perpendicular to the bed joints....

  20. Isolating roughness scales of gravel-bed patches

    Science.gov (United States)

    Bertin, Stephane; Groom, Jane; Friedrich, Heide

    2017-08-01

    There is a growing consensus that gravel-bed roughness should be parameterized based on bed-surface topography, not only sediment size. One benefit is the possible identification of various spatial scales of surface roughness and evaluation of their respective contributions to flow resistance (and also to bedload transport). The absence of relationships between roughness at the different scales is apparent in previous work, which currently limits roughness parameterization from topography and application in flow modeling. This study examines the use of moving-window detrending on gravel-bed digital elevation models (DEMs) for isolating roughness scales and their respective signatures. A large data set of 35 water-worked gravel-bed patches from both the laboratory and the field was used for the analysis. The measured bed topography was separated into two distinct DEMs: one representing grains, the other representing small bedforms. For all DEMs, bed-elevation parameters measuring vertical roughness, imbrication, and spatial correlations were determined. Our results show distinct topographic signatures between grain and bedform DEMs. We show strong positive linear relationships between grain vertical roughness and the size of the bed-surface material. Surface sediment arrangement also determined bedform shape, with groupings of coarse sediment forming humps on the surface, and finer sediment sheltered in hollows. Patch-scale vertical roughness could not be estimated simply as the sum of grain and bedform vertical roughness. Instead, our results suggest weighted summation and the existence of universal weighting coefficients. Practical applications for studies on gravel-bed roughness and flow modeling using DEMs are discussed.

  1. Particle motions in oscillatory flow over a smooth bed

    DEFF Research Database (Denmark)

    Jensen, Karsten Lindegård; Sumer, B. Mutlu; Fredsøe, Jørgen

    2014-01-01

    This study investigates particle motions near the bed in an oscillating tunnel with a smooth bed. Trajectories of a heavy particle were recorded in two dimensions (horizontal and vertical) and in time. The wave boundary layer Reynolds number is Re = 520000. Kinematical quantities...... such as the probability distribution of particle position in the vertical, and the horizontal and vertical particle velocities, among others, are determined. The particle is observed to reach heights of 2.5-3d, similar to that characterizing a typical bedload particle in sediment transport....

  2. Dynamic behavior and control requirements of an atmospheric fluidized-bed coal combustion power plant: A conceptual study

    Energy Technology Data Exchange (ETDEWEB)

    Smith, O.L.

    1987-06-01

    A first-principles model of a nominal 20-MW atmospheric-pressure fluidized-bed coal combustion (AFBC) power plant was developed to provide insight into fundamental dynamic behavior of fluidized-bed systems. The control system included major loops for firing rate, steam pressure and temperature, forced and induced draft air flow, SO/sub 2/ emission, drum water level, evaporator recirculation, and bed level. The model was used to investigate system sensitivity to design features such as the distribution of heat transfer surface among the bed boiler and superheater and the out-of-bed superheater. Also calculated were the sensitivities of temperatures, pressures, and flow rates to changes in throttle, attemperator, and feedwater valve settings and forced and induced draft damper settings. The large bed mass, accounting for approx.40% of the active heat capacity, may vary under load change and could impact controller tuning. Model analysis indicated, however, that for the design studied, the change in bed mass does not appear to significantly affect controller tuning even if the bed mass varies appreciably under load-following conditions. Several bed designs are being considered for AFBC plants, some with partitions between bed sections and some without, and these differences may significantly affect the load-following capability of the plant. The results indicated that the slumping mode of operation can cause distortion of the heat source/sink distribution in the bed such that the load-following capability (rate of load change) of the plant may be reduced by as much as a factor of 5 compared with the mode in which tube surface is exposed. 9 refs., 13 figs., 6 tabs.

  3. Determining the contribution of long-range transport, regional and local source areas, to PM10 mass loading in Hessen, Germany using a novel multi-receptor based statistical approach

    Science.gov (United States)

    Garg, Saryu; Sinha, Baerbel

    2017-10-01

    This study uses two newly developed statistical source apportionment models, MuSAM and MuReSAM, to perform quantitative statistical source apportionment of PM10 at multiple receptor sites in South Hessen. MuSAM uses multi-site back trajectory data to quantify the contribution of long-range transport, while MuReSAM uses wind speed and direction as proxy for regional transport and quantifies the contribution of regional source areas. On average, between 7.8 and 9.1 μg/m3 of PM10 (∼50%) at receptor sites in South Hessen is contributed by long-range transport. The dominant source regions are Eastern, South Eastern, and Southern Europe. 32% of the PM10 at receptor sites in South Hessen is contributed by regional source areas (2.8-9.41 μg/m3). This fraction varies from 40% for urban stations. Sources located within a 2 km radius around the receptor site are responsible for 7%-20% of the total PM10 mass (0.7-4.4 μg/m3). The perturbation study of the traffic flow due to the closing and reopening of the Schiersteiner Brücke revealed that the contribution of the bridge to PM10 mass loadings at two nearby receptor sites increased by approximately 120% after it reopened and became a bottleneck, although in absolute terms, the increase is small.

  4. Bed Bugs: The Australian Response

    Directory of Open Access Journals (Sweden)

    Richard C. Russell

    2011-04-01

    Full Text Available Australia has experienced a sudden and unexpected resurgence in bed bug infestations from both Cimex lectularius L. and Cimex hemipterus F. A survey in 2006 revealed that infestations had increased across the nation by an average of 4,500% since the start of the decade. In response, a multi-disciplinary approach to combat the rise of this public health pest was implemented and involved the coordinated efforts of several organizations. The key components of the strategy included the introduction of a pest management standard ‘A Code of Practice for the Control of Bed Bug Infestations in Australia’ that defines and promotes ‘best practice’ in bed bug eradication, the development of a policy and procedural guide for accommodation providers, education of stakeholders in best management practices, and research. These strategies continue to evolve with developments that lead to improvements in ‘best practice’ while bed bugs remain problematic in Australia.

  5. Getting Rid of Bed Bugs

    Science.gov (United States)

    ... control is very important whether you are considering hiring a professional or planning to do it yourself. Controlling bed ... control methods, as others may cause serious harm. Hiring a pest management professional is a good option in many cases, but ...

  6. Sea bed mapping and inspection

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2006-07-01

    The conference has 24 presentations on the topics: Sea bed mapping, inspection, positioning, hydrography, marine archaeology, remote operation vehicles and computerized simulation technologies, oil field activities and plans, technological experiences and problems. (tk)

  7. Styrene biofiltration in a trickle-bed reactor

    Directory of Open Access Journals (Sweden)

    V. Novak

    2008-04-01

    Full Text Available The biological treatment of styrene waste gas in a trickle-bed filter (TBF was investigated. The bioreactor consisted of a two-part glass cylinder (ID 150 mm filled with 25 mm polypropylene Pall rings serving as packing material. The bed height was 1m. Although the laboratory temperature was maintained at 22 ºC, the water temperature in the trickle-bed filter was slightly lower (about 18 ºC.The main aim of our study was to observe the effect of empty-bed residence time (EBRT on bioreactor performance at a constant pollutant concentration over an extended time period. The bioreactor was inoculated with a mixed microbial consortium isolated from a styrene-degrading biofilter that had been running for the previous two years. After three weeks of acclimation period, the bioreactor was loaded with styrene (100 mg.m-3. EBRT was in the range of 53 s to 13 s. A maximum elimination capacity (EC of 11.3 gC.m-3.h-1 was reached at an organic loading (OL rate of 18.6 gC.m-3.h-1.

  8. Rock bed storage with heat pump. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Remmers, H.E.; Mills, G.L.

    1979-05-01

    The study, Rock Bed Storage with Heat Pump, established the feasibility of mating a heat pump to a rock bed storage to effect optimal performance at the lowest cost in single family residences. The operating characteristics of off-the-shelf components of heat pump/rock bed storage systems were studied, and the results were used to formulate configurations of representative systems. These systems were modeled and subsequently analyzed using the TRNSYS computer program and a life cycle cost analysis program called LCCA. A detailed load model of a baseline house was formulated as part of the TRNSYS analysis. Results of the analysis involved the development of a technique to confine the range of heat pump/rock bed storage systems to those systems which are economical for a specific location and set of economic conditions. Additionally, the results included a comparison of the detailed load model with simple UA models such as the ASHRAE bin method. Several modifications and additions were made to the TRNSYS and LCCA computer programs during the course of the study.

  9. Operating characteristics of rotating beds

    Energy Technology Data Exchange (ETDEWEB)

    Keyvani, M.; Gardner, N.C.

    1988-01-01

    Vapor-liquid contacting in high gravitational fields offers prospects for significant reductions in the physical size, capital, and operating costs of packed towers. Pressure drops, power requirements, mass transfer coefficients and liquid residence time distributions are reported for a rotating bed separator. The beds studied were rigid, foamed aluminum, with specific surface areas ranging from 650 to 3000 m{sup 2}/m{sup 2}. Gravitational fields were varied from 50 to 300g.

  10. Sediment transport dynamics in the Central Himalaya: assessing during monsoon the erosion processes signature in the daily suspended load of the Narayani river

    Science.gov (United States)

    Morin, Guillaume; Lavé, Jérôme; Lanord, Christian France; Prassad Gajurel, Ananta

    2017-04-01

    The evolution of mountainous landscapes is the result of competition between tectonic and erosional processes. In response to the creation of topography by tectonics, fluvial, glacial, and hillslope denudation processes erode topography, leading to rock exhumation and sediment redistribution. When trying to better document the links between climate, tectonic, or lithologic controls in mountain range evolution, a detailed understanding of the influence of each erosion process in a given environment is fundamental. At the scale of a whole mountain range, a systematic survey and monitoring of all the geomorphologic processes at work can rapidly become difficult. An alternative approach can be provided by studying the characteristics and temporal evolution of the sediments exported out of the range. In central Himalaya, the Narayani watershed presents contrasted lithologic, geochemical or isotopic signatures of the outcropping rocks as well as of the erosional processes: this particular setting allows conducting such type of approach by partly untangling the myopic vision of the spatial integration at the watershed scale. Based on the acquisition and analysis of a new dataset on the daily suspended load concentration and geochemical characteristics at the mountain outlet of one of the largest Himalayan rivers (drainage area = 30000 km2) bring several important results on Himalayan erosion, and on climatic and process controls. 1. Based on discrete depth sampling and on daily surface sampling of suspended load associated to flow characterization through ADCP measurements, we were first able to integrate sediment flux across a river cross-section and over time. We estimate for 2010 year an equivalent erosion rate of 1.8 +0.35/-0.2 mm/yr, and over the last 15 years, using past sediment load records from the DHM of Nepal, an equivalent erosion rate of 1.6 +0.3/-0.2 mm/yr. These rates are also in close agreement with the longer term ( 500 yrs) denudation rates of 1.7 mm

  11. Shaft placement in a bedded salt repository

    International Nuclear Information System (INIS)

    Klasi, M.L.

    1982-10-01

    Preferred shaft pillar sizes and shaft locations were determined with respect to the induced thermal stresses in a generic bedded salt repository at a depth of 610 m with a gross thermal loading of 14.8 W/m 2 . The model assumes isotropic material properties, plane strain and linear elastic behavior. Various shaft locations were analyzed over a 25 year period. The thermal results show that for this time span, the stratigraphy is unimportant except for the region immediately adjacent to the repository. The thermomechanical results show that for the given repository depth of 610 m, a minimum central shaft pillar radius of 244 m is required to equal the material strength in the barrier pillar. An assumed constant stress and constant temperature distribution creep model of the central shaft region adjacent to the repository conservatively overestimates a creep closure of 310 mm in a 6.1 m diameter centrally-located shaft

  12. Dynamic transition between fixed- and mobile-bed: mathematical and numerical aspects

    Science.gov (United States)

    Zugliani, Daniel; Pasqualini, Matteo; Rosatti, Giorgio

    2017-04-01

    Free-surface flows with high sediment transport (as debris flow or hyper-concentrated flow) are composed by a mixture of fluid and solid phase, usually water and sediment. When these flows propagate over loose beds, particles constituting the mixture of water and sediments strongly interact with the ones forming the bed, leading to erosion or deposition. However, there are lots of other situations when the mixture flows over rigid bedrocks or over artificially paved transects, so there is no mass exchange between bed and mixture. The two situations are usually referred to as, respectively, mobile- and fixed-bed conditions. From a mathematical point of view, the systems of Partial Differential Equations (PDEs) that describe these flows derive from mass and momentum balance of both phases, but, the two resulting PDEs systems are different. The main difference concerns the concentration: in the mobile-bed condition, the concentration is linked to the local flow conditions by means of a suitable rheological relation, while in the fixed-bed case, the concentration is an unknown of the problem. It is quite common that a free surface flow with high sediment transport, in its path, encounters both conditions. In the recent work of Rosatti & Zugliani 2015, the mathematical and numerical description of the transition between fixed- and mobile-bed was successfully resolved, for the case of low sediment transport phenomena, by the introduction of a suitable erodibility variable and satisfactory results were obtained. The main disadvantage of the approach is related to the erodibility variable, that changes in space, based on bed characteristics, but remains constant in time. However, the nature of the bed can change dynamically as result of deposition over fixed bed or high erosion over mobile bed. With this work, we extend the applicability of the mentioned approach to the more complex PDEs describing the hyper-concentrated flow. Moreover, we introduce a strategy that allows

  13. Biofilm detachment mechanisms in a liquid-fluidized bed.

    Science.gov (United States)

    Chang, H T; Rittmann, B E; Amar, D; Heim, R; Ehlinger, O; Lesty, Y

    1991-08-20

    Bed fluidization offers the possibility of gaining the advantages of fixed-film biological processes without the disadvantage of pore clogging. However, the biofilm detachment rate, due to hydrodynamics and particle-to-particle attrition, is very poorly understood for fluidized-bed biofilm processes. In this work, a two-phase fluidized-bed biofilm was operated under a constant surface loading (0.09 mg total organic carbon/cm(2) day) and with a range of bed height (H), fluid velocities (U), and support-particle concentrations (C(p)). Direct measurements were made for the specific biofilm loss rate coefficient (b(s))and the total biofilm accumulation (X(f)L(f)). A hydrodynamic model allowed independent determination of the biofilm density (X(f)), biofilm thickness (L(f)), liquid shear stress (tau), and Reynolds number (Re). Multiple regression analysis of the results showed that increased particle-to-particle attrition, proportional to C(p) and increased turbulence, described by Re, caused the biofilms to be denser and thinner. The specific detachment rate coefficient (b(s)) increased as C(p) and Re increased. Almost all of the 6, values were larger than predicted by a previous model derived for smooth biofilms on a nonfluidized surface. Therefore, the turbulence and attrition of bed fluidization appear to be dominant detachment mechanisms.

  14. Borehole-inclusion stressmeter measurements in bedded salt

    International Nuclear Information System (INIS)

    Cook, C.W.; Ames, E.S.

    1980-07-01

    Sandia purchased borehole-inclusion stressmeters from a commercial supplier to measure in situ stress changes in bedded salt. However, the supplied stressmeters were difficult to set in place and gave erratic results in bedded salt. These problems were overcome with a new extended platen design. Also a straingaged transducer was designed which can be read with a conventional data logger. Due to the nonlinear behavior of bedded salt under uniaxial loading, a new empirical calibration scheme was devised. In essence, the stressmeters are calibrated as force transducers and this calibration curve is then used to determine the relationship between uniaxial stress changes in bedded salt and the gage's output. The stressmeter and calibration procedures have been applied under mine conditions and produced viable results. Future work will involve finite element analysis to calculate the observed behavior of the stressmeters. The response of the stressmeters in bedded salt is neither that of a true stressmeter or of a true strainmeter. However, repeatable calibrations make the gages very useful

  15. Modeling sediment transport after ditch network maintenance of a forested peatland

    Science.gov (United States)

    Haahti, K.; Marttila, H.; Warsta, L.; Kokkonen, T.; Finér, L.; Koivusalo, H.

    2016-11-01

    Elevated suspended sediment (SS) loads released from peatlands after drainage operations and the resulting negative effect on the ecological status of the receiving water bodies have been widely recognized. Understanding the processes controlling erosion and sediment transport within the ditch network forms a prerequisite for adequate sediment control. While numerous experimental studies have been reported in this field, model based assessments are rare. This study presents a modeling approach to investigate sediment transport in a peatland ditch network. The transport model describes bed erosion, rain-induced bank erosion, floc deposition, and consolidation of the bed. Coupled to a distributed hydrological model, sediment transport was simulated in a 5.2 ha forestry-drained peatland catchment for 2 years after ditch cleaning. Comparing simulation results to measured SS concentrations suggested that the loose peat material, produced during excavation, contributed markedly to elevated SS concentrations immediately after ditch cleaning. Both snowmelt and summer rainstorms contributed critically to annual loads. Springtime peat erosion during snowmelt was driven by ditch flow whereas during summer rainfalls, bank erosion by raindrop impact was identified as an important process. Relating modeling results to observed spatial topographic changes in the ditch network was challenging and the results were difficult to verify. Nevertheless, the model has potential to identify risk areas for erosion. The results demonstrate that modeling is effective in separating the importance of different processes and complements pure experimental approaches. Modeling results can aid planning and designing efficient sediment control measures and guide the focus of experimental studies.

  16. Mechanisms for decreased exercise capacity after bed rest in normal middle-aged men

    Energy Technology Data Exchange (ETDEWEB)

    Hung, J.; Goldwater, D.; Convertino, V.A.; McKillop, J.H.; Goris, M.L.; DeBusk, R.F.

    1983-01-15

    The mechanisms responsible for the decrease in exercise capacity after bed rest were assessed in 12 apparently healthy men aged 50 +/- 4 years who underwent equilibrium gated blood pool scintigraphy during supine and upright multistage bicycle ergometry before and after 10 days of bed rest. After bed rest, echocardiographically measured supine resting left ventricular end-diastolic volume decreased by 16% (p less than 0.05). Peak oxygen uptake during supine effort after bed rest was diminished by 6% (p . not significant (NS)), whereas peak oxygen uptake during upright effort declined by 15% (p less than 0.05). After bed rest, increases in heart rate were also greater during exercise in the upright than in the supine position (p less than 0.05). Values of left ventricular ejection fraction increased normally during both supine and upright effort after bed rest and were higher than corresponding values before bed rest (p less than 0.05). After bed rest, increased left ventricular ejection fraction and heart rate largely compensated for the reduced cardiac volume during supine effort, but these mechanisms were insufficient to maintain oxygen transport capacity at levels during upright effort before bed rest. These results indicate that orthostatically induced cardiac underfilling, not physical deconditioning or left ventricular dysfunction, is the major cause of reduced effort tolerance after 10 days of bed rest in normal middle-aged men.

  17. Variability of solid load in the proglacial Fagge River, Tyrol (Austria)

    Science.gov (United States)

    Baewert, Henning; Weber, Martin; Faust, Matthias; Morche, David

    2016-04-01

    Glaciers can strongly affect sediment dynamics in high-mountain basins. They receive clastic material from rock walls by gravitational processes of various magnitudes (rock slides to rockfalls) or by subglacial erosion and transport sediments downvalley like a conveyor belt. At the glacier tongue the meltwater with its accompanying river load enters the proglacial system. Fine material is moving in suspension leading to turbid meltwater. The coarse fraction of the meltwater load is rolling or sliding as bedload on the proglacial channel bed. As glaciers are vulnerable to and thus indicators of climate change the sediment transfer systems in Alpine glacier basins will respond as well. Since the end of the Little Ice Age (LIA) around 1850 glacier in the European Alps have been melting down and their front lines have been retreating. Where the glacier ice is gone large amounts unconsolidated sediments are deposited (moraines, glaciofluvial deposits) and can easily be reworked during subsequent rain storms or snowmelt. As a consequence it is of great concern whether more solid load (higher sediment availability) or less solid load (trapping effect of proglacial lakes) is transported in proglacial rivers in the near future. Due to glacier retreat the amount of unconsolidated, sparsely vegetated sediments, which are prone to rapid remobilization, is increasing. Because more of these sediments are available for fluvial sediment transport, it is generally assumed that glacier retreat leads to an increase in sediment discharge from proglacial zones. The main objective of this study is to present a budget of the fluvial sediment transport within the proglacial Fagge River for the observation period 2012 - 2014. This quantification of solid sediment transport is needed for further investigations on the way to a holistic sediment budget for the whole glaciated catchment of the Gepatschferner in Tyrol/Austria.

  18. Feasibility study - Lowered bed temperature in Fluidised Bed boilers for waste; Foerstudie - Saenkt baeddtemperatur i FB-pannor foer avfallsfoerbraenning

    Energy Technology Data Exchange (ETDEWEB)

    Niklasson, Fredrik

    2009-01-15

    Waste incineration generally serves two purposes; 1) dispose of waste and 2) generation of heat and power. In the process of power production from waste fuels, the steam temperatures in super heaters are generally limited by the severe fouling and corrosion that occurs at elevated material temperatures, caused by high concentrations of alkali metals and chloride in the flue gas and fly ash. The overall aim of a continuation of present project is to determine if a reduced temperature of the bed zone in a fluidized bed waste incinerator reduces the amount of alkali chlorides in the flue gas. If so, a reduced bed temperature might enable increased steam temperature in super heaters, or, at unchanged steam temperature, improve the lifespan of the super heaters. The results from the project are of interest for plant owners wishing to improve performance of existing plants. The results may also be used to modify the design of future plants by boiler manufacturers. The aim of present pre-study was to determine how far the bed temperature can be reduced in a waste fired fluidized bed boiler in Boraas while maintaining a stable operation with sufficient combustion temperature in the freeboard to fulfil the directives of waste incineration. A continuation of the project will be based on the results from present study. The work is based on experiments at the test boiler. During the present study, no other measurements were performed apart from some sampling of bed material and ashes at different modes of operation. The experiments show that it is possible to alter the air and recycled flue gas in such a manner that the bed temperature is reduced from about 870 deg C to 700 deg C at 100% load and normal fuel mixture, while fulfilling the directive of 850 deg C at 2 seconds. Within normal variations of the fuel properties, however, the bed temperature increases to somewhat above 700 deg C if the fuel turns dry, while it falls below 650 deg C when the fuel turns wet. With

  19. The Kaldnes Moving Bed biofilm technology for treatment of industrial wastewater; Tecnologia Kaldnes Moving Bed biofilm (KMT) para la depuracion de aguas residuales industriales

    Energy Technology Data Exchange (ETDEWEB)

    Rasmussen, V.; Garcia Carrion, M.; Farre Solsona, C.

    2004-07-01

    The Kaldnes Moving bed biofilm technology is a biofilm process which is very suitable for treatment of industrial wastewaters. Biofilm processes have several acknowledged advantages compared to suspended biomass processes, e. g. resistance to toxicity and load variations. Traditionally biofilm processes have been known to clog at high loads and hence have not been suited for industrial effluents: however, the Kaldnes Moving Bed biofilm process has overcome this problem. This article describes how the process has been used as pre-treatment up front of activated sludge at a dairy in USA, and as sole treatment at pharmaceutical industry in Sweden. (Author)

  20. Used Nuclear Fuel Loading and Structural Performance Under Normal Conditions of Transport- Demonstration of Approach and Results on Used Fuel Performance Characterization

    Energy Technology Data Exchange (ETDEWEB)

    Adkins, Harold [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Geelhood, Ken [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Koeppel, Brian [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Coleman, Justin [Idaho National Lab. (INL), Idaho Falls, ID (United States); Bignell, John [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Flores, Gregg [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Wang, Jy-An [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Sanborn, Scott [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Spears, Robert [Idaho National Lab. (INL), Idaho Falls, ID (United States); Klymyshyn, Nick [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2013-09-30

    This document addresses Oak Ridge National Laboratory milestone M2FT-13OR0822015 Demonstration of Approach and Results on Used Nuclear Fuel Performance Characterization. This report provides results of the initial demonstration of the modeling capability developed to perform preliminary deterministic evaluations of moderate-to-high burnup used nuclear fuel (UNF) mechanical performance under normal conditions of storage (NCS) and normal conditions of transport (NCT) conditions. This report also provides results from the sensitivity studies that have been performed. Finally, discussion on the long-term goals and objectives of this initiative are provided.

  1. Time/motion observations and dose analysis of reactor loading, transportation, and dry unloading of an overweight truck spent fuel shipment

    International Nuclear Information System (INIS)

    Hostick, C.J.; Lavender, J.C.; Wakeman, B.H.

    1992-04-01

    This document presents observed activity durations and radiation dose analyses for an overweight truck shipment of pressurized water reactor (PWR) spent fuel from the Surry Power Station in Virginia to the Idaho National Engineering Laboratory. The shipment consisted of a TN-8L shipping cask carrying three 9-year-old PWR spent fuel assemblies. Handling times and dose analyses for at-reactor activities were completed by Virginia Electric and Power Company (Virginia Power) personnel. Observations of in-transit and unloading activities were made by Pacific Northwest Laboratory (PNL) personnel, who followed the shipment for approximately 2800 miles and observed cask unloading activities. In-transit dose estimates were calculated using dose rate maps provided by Virginia Power for a fully loaded TN-8L shipping cask. The dose analysis for the cask unloading operations is based on the observations of PNL personnel

  2. Phase transition behavior of sediment transport at the sand-mud interface, across scales from flumes to the large rivers

    Science.gov (United States)

    Ma, H.; Nittrouer, J. A.; Wu, B.; Zhang, Y.; Mohrig, D. C.; Lamb, M. P.; Wang, Y.; Fu, X.; Moodie, A. J.; Naito, K.; Parker, G.

    2017-12-01

    Sediment dispersal and deposition creates deltaic landscapes, establishes coastlines, and produces fertile floodplains, all of which serve as critical landforms inhabited by a large proportion of humankind. If poorly managed, sediment loads in these environments can elevate and clog channels, thereby enhancing hazards such as severe flooding. Predictive descriptions of sediment loads, however, are not well constrained, especially for fine-grained (silt and very-fine sand) dispersal systems, which often include river deltas and coastlines. Here, we show efforts to collect and analyze an extensive sediment load database for fine-grained channels, spanning from small flume experiments to large rivers, in order to evaluate the nature of sediment flux. Our analyses determined that sediment transport exhibits two distinct transport phases, separated by a discontinuous transition, whereby sediment flux differs by one to two orders of magnitude. It is determined that the transition responds to the bed material grain size, and we propose a phase diagram based on this metric alone. These findings help elucidate why previous theories of sediment transport at the sand-silt interface, which are typically continuous, are not able to give satisfactory predictions across different scales and environments. Our work serves to help evaluate anthropic influences on rivers, deltas, and coastlines, and can be applied to better constrain sediment flux of paleo-fluvial systems found on Earth and Mars. For example, in situ measurements of sediment flux for the silty-sandy bed of the lower Yellow River, China, validate the aforementioned phase transition behavior, and illustrate that the channel resides near the transition of high to low efficiency transport modes. Recent dam construction and resulting downstream coarsening of the bed via armoring, however, might lead to the unintended consequence of enhancing flood risk by driving the system to a low efficiency transport mode with high

  3. Hydrodynamic studies in designing of fluidized bed system

    International Nuclear Information System (INIS)

    Mohamad Puad Abu; Muhd Noor Muhd Yunus; Syed Nasaruddin Syed Idris

    2002-01-01

    Fluidized bed process have been used mostly in the petroleum and paper industries, and for processing nuclear wastes, spent cook liquor, wood chips, and sewage sludge disposal. Even at MINT some of the equipment available used this principal. Before we use or purchase this equipment, it is very grateful if we could understand how the system has been designed. The hydrodynamic fluidization studies is very important in designing of fluidized bed system especially in determining the minimum fluidizing velocity, terminal velocity, flexibility of operation, slugging condition, bubble size and velocity, and transport disengaging height. They can be determined either by calculation or experimentation. This paper will highlight the hydrodynamic study that need to be performed in designing of fluidized bed system so that its can be used appropriately. (Author)

  4. Estimated Loads of Suspended Sediment and Selected Trace Elements Transported through the Milltown Reservoir Project Area Before and After the Breaching of Milltown Dam in the Upper Clark Fork Basin, Montana, Water Year 2008

    Science.gov (United States)

    Lambing, John H.; Sando, Steven K.

    2009-01-01

    This report presents estimated daily and cumulative loads of suspended sediment and selected trace elements transported during water year 2008 at three streamflow-gaging stations that bracket the Milltown Reservoir project area in the upper Clark Fork basin of western Montana. Milltown Reservoir is a National Priorities List Superfund site where sediments enriched in trace elements from historical mining and ore processing have been deposited since the construction of Milltown Dam in 1907. Milltown Dam was breached on March 28, 2008, as part of Superfund remedial activities to remove the dam and contaminated sediment that had accumulated in Milltown Reservoir. The estimated loads transported through the project area during the periods before and after the breaching of Milltown Dam, and for the entire water year 2008, were used to quantify the net gain or loss (mass balance) of suspended sediment and trace elements within the project area during the transition from a reservoir environment to a free-flowing river. This study was done in cooperation with the U.S. Environmental Protection Agency. Streamflow during water year 2008 compared to long-term streamflow, as represented by the record for Clark Fork above Missoula (water years 1930-2008), generally was below normal (long-term median) from about October 2007 through April 2008. Sustained runoff started in mid-April, which increased flows to near normal by mid-May. After mid-May, flows sharply increased to above normal, reaching a maximum daily mean streamflow of 16,800 cubic feet per second (ft3/s) on May 21, which essentially equaled the long-term 10th-exceedance percentile for that date. Flows substantially above normal were sustained through June, then decreased through the summer and reached near-normal by August. Annual mean streamflow during water year 2008 (3,040 ft3/s) was 105 percent of the long-term mean annual streamflow (2,900 ft3/s). The annual peak flow (17,500 ft3/s) occurred on May 21 and was 112

  5. Assembly procedure for Shot Loading Platform

    International Nuclear Information System (INIS)

    Routh, R.D.

    1995-01-01

    This supporting document describes the assembly procedure for the Shot Loading Platform. The Shot Loading Platform is used by multiple equipment removal projects to load shielding shot in the annular spaces of the equipment storage containers. The platform height is adjustable to accommodate different sizes of storage containers and transport assemblies

  6. Reactive-transport simulation of phosphorus in the sewage plume at the Massachusetts Military Reservation, Cape Cod, Massachusetts

    Science.gov (United States)

    Parkhurst, David L.; Stollenwerk, Kenneth G.; Colman, John A.

    2003-01-01

    The subsurface transport of phosphorus introduced by the disposal of treated sewage effluent to ground-infiltration disposal beds at the Massachusetts Military Reservation on western Cape Cod was simulated with a three-dimensional reactive-transport model. The simulations were used to estimate the load of phosphorus transported to Ashumet Pond during operation of the sewage-treatment plant?from 1936 to 1995?and for 60 years following cessation of sewage disposal. The model accounted for spatial and temporal changes in water discharge from the sewage-treatment plant, ground-water flow, transport of associated chemical constituents, and a set of chemical reactions, including phosphorus sorption on aquifer materials, dissolution and precipitation of iron- and manganese-oxyhydroxide and iron phosphate minerals, organic carbon sorption and decomposition, cation sorption, and irreversible denitrification. The flow and transport in the aquifer were simulated by using parameters consistent with those used in previous flow models of this area of Cape Cod, except that numerical dispersion was much larger than the physical dispersion estimated in previous studies. Sorption parameters were fit to data derived from phosphorus sorption and desorption laboratory column experiments. Rates of organic carbon decomposition were adjusted to match the location of iron concentrations in an anoxic iron zone within the sewage plume. The sensitivity of the simulated load of phosphorus transported to Ashumet Pond was calculated for a variety of processes and input parameters. Model limitations included large uncertainties associated with the loading of the sewage beds, the flow system, and the chemistry and sorption characteristics in the aquifer. The results of current model simulations indicate a small load of phosphorus transported to Ashumet Pond during 1965?85, but this small load was particularly sensitive to model parameters that specify flow conditions and the chemical process by

  7. Can we predict the response of large sand bed rivers to changes in flow and sediment supply? The case of the Missouri River.

    Science.gov (United States)

    Viparelli, E.; Blum, M. D.

    2015-12-01

    In the past century engineering projects and changes in land use significantly modified the hydrology and the sediment supply of large sand bed rivers all over the world. Field studies documented the river responses to the imposed changes, which can be summarized as adjustments in channel geometry, slope, and/or characteristics of the bed material. Further, one-, two- and three-dimensional river morphodynamic models were used to predict the fluvial system response to the imposed changes at time scales ranging from few months up to several decades. Notwithstading this previous research effort, the spatial and temporal scales of river adjustment, as well as quantitative predictions of the river responses, are still a matter of debate due to the difficulties associated with the interpretation of limited field datasets and with the large scale sediment transport modeling. Here we present the preliminary results of a study of the Missouri River response to the construction of dams, i.e. reduction in flood flow and sediment supply. In particular, we first compare the numerical results of a one-dimensional model of river morphodynamics for large, low slope sand bed rivers with field data to validate the model. The validated model is then used to constrain the spatial and temporal scales of the river adjustment, i.e. bed degradation in the Missouri River case. In other words, our numerical work focuses on how the magnitude and speed of the wave of channel bed degradation changes in time and space for the Missouri River case and how these scales change for different values of the ratio between pre- and pos-dam flow rates, and pre- and post-dam sediment loads.

  8. Three dimensional model for particle saltation close to stream beds, including a detailed description of the particle interaction with turbulence and inter-particle collisions

    KAUST Repository

    Moreno, Pablo M.

    2011-05-19

    We present in this paper a new three-dimensional (3-D) model for bed-load sediment transport, based on a Lagrangian description. We analyze generalized sub-models for the velocities after collision and the representation of the bed-roughness. The free-flight sub-model includes the effect of several forces, such as buoyancy, drag, virtual mass, lift, Basset and Magnus, and also addresses the particle rotation. A recent methodology for saving computational time in the Basset force is also employed. The sub-models for the post-collision velocity and rotation are based on the conservation of linear and angular momentum during the collision with the bed. We develop a new 3-D representation for the bed roughness by using geometric considerations. In order to address the interaction of particles with the turbulent flow, we tracked the particles through a computed turbulent velocity field for a smooth flat plate. This velocity field was used as a surrogate of the 3-D turbulent conditions close to the bed in streams. We first checked that the basic turbulence statistics for this velocity field could be used to approximate those in an open-channel flow. We then analyzed the interaction of the sediment and the turbulence for a single and multiple particles. We compared numerical results with experimental data obtained by Niño and García (1998b). We show that model predictions are in good agreement with existing data, in the sand size range. © 2011 ASCE.

  9. A Comparison of Tandem Walk Performance Between Bed Rest Subjects and Astronauts

    Science.gov (United States)

    Miller, Chris; Peters, Brian; Kofman, Igor; Philips, Tiffany; Batson, Crystal; Cerisano, Jody; Fisher, Elizabeth; Mulavara, Ajitkumar; Feiveson, Alan; Reschke, Millard; hide

    2015-01-01

    Astronauts experience a microgravity environment during spaceflight, which results in a central reinterpretation of both vestibular and body axial-loading information by the sensorimotor system. Subjects in bed rest studies lie at 6deg head-down in strict bed rest to simulate the fluid shift and gravity-unloading of the microgravity environment. However, bed rest subjects still sense gravity in the vestibular organs. Therefore, bed rest isolates the axial-unloading component, thus allowing for the direct study of its effects. The Tandem Walk is a standard sensorimotor test of dynamic postural stability. In a previous abstract, we compared performance on a Tandem Walk test between bed rest control subjects, and short- and long-duration astronauts both before and after flight/bed rest using a composite index of performance, called the Tandem Walk Parameter (TWP), that takes into account speed, accuracy, and balance control. This new study extends the previous data set to include bed rest subjects who performed exercise countermeasures. The purpose of this study was to compare performance during the Tandem Walk test between bed rest subjects (with and without exercise), short-duration (Space Shuttle) crewmembers, and long-duration International Space Station (ISS) crewmembers at various time points during their recovery from bed rest or spaceflight.

  10. Development of fluidized bed combustion of biomass; Leijupolttoprosessin kehittaeminen vaikeille biopolttoaineille soveltuvaksi

    Energy Technology Data Exchange (ETDEWEB)

    Hiltunen, M.; Vaehaenen-Koivuluoma, T. [Foster Wheeler Energia Oy, Karhula (Finland)

    1997-10-01

    Some commercial BFB boilers burning biofuels, or biofuels and industrial wood wastes have suffered serious problems in bed material sintering. In worst cases the cumulation of reactive alkali compounds has caused total sintering of bed material even during a few days` operation. This presentation reports the results obtained from three separate cases, where sintering problems occurred. Boiler A burned biofuel with quartz sand and limestone addition. Boiler B burned softwood bark and industrial wood waste with sand addition. Boiler C burned softwood bark and sludge with sand addition. Due to the fuel used, bed sintering occurred in all boilers. Obviously, sintering was also influenced by some technical problems. Bed material samples have been analyzed with XRF and SEM-EDS techniques. According to these analyses, the main reason for sintering in boiler A is the cumulation of reactive potassium in bed material. In boiler B, the main reason is the fuel change from a mixture of softwood bark and industrial wood waste to pure industrial wood waste. The extra load of reactive sodium exceeded the critical concentration of alkali compounds in bed material. Also in boiler C, the fuel change from a mixture of softwood bark and sludge to pure softwood bark seems to be one of the reasons for bed sintering. After the fuel change the bed saturated with reactive potassium and the bed sintered. (orig.)

  11. Effects of Fourteen-Day Bed Rest on Trunk Stabilizing Functions in Aging Adults

    Directory of Open Access Journals (Sweden)

    Nejc Sarabon

    2015-01-01

    Full Text Available Bed rest has been shown to have detrimental effects on structural and functional characteristics of the trunk muscles, possibly affecting trunk and spinal stability. This is especially important in populations such as aging adults with often altered trunk stabilizing functions. This study examined the effects of a fourteen-day bed rest on anticipatory postural adjustments and postural reflex responses of the abdominal wall and back muscles in sixteen adult men. Postural activation of trunk muscles was measured using voluntary quick arm movement and sudden arm loading paradigm. Measurements were conducted prior to the bed rest, immediately after, and fourteen days after the bed rest. Immediately after the bed rest, latencies of anticipatory postural adjustments showed significant shortening, especially for the obliquus internus and externus muscles. After a fourteen-day recuperation period, anticipatory postural adjustments reached a near to complete recovery. On the contrary, reactive response latencies increased from pre-bed-rest to both post-bed-rest measurement sessions. Results indicate an important effect of bed rest on stabilizing functions of the trunk muscles in elderly adults. Moreover, there proved to be a significant deterioration of postural reactive responses that outlasted the 14-day post-bed-rest rehabilitation.

  12. Particle Size Distribution Controls the Threshold Between Net Sediment Erosion and Deposition in Suspended Load Dominated Flows

    Science.gov (United States)

    Dorrell, R. M.; Amy, L. A.; Peakall, J.; McCaffrey, W. D.

    2018-02-01

    The central problem of describing most environmental and industrial flows is predicting when material is entrained into, or deposited from, suspension. The threshold between erosional and depositional flow has previously been modeled in terms of the volumetric amount of material transported in suspension. Here a new model of the threshold is proposed, which incorporates (i) volumetric and particle size limits on a flow's ability to transport material in suspension, (ii) particle size distribution effects, and (iii) a new particle entrainment function, where erosion is defined in terms of the power used to lift mass from the bed. While current suspended load transport models commonly use a single characteristic particle size, the model developed herein demonstrates that particle size distribution is a critical control on the threshold between erosional and depositional flow. The new model offers an order of magnitude, or better, improvement in predicting the erosional-depositional threshold and significantly outperforms existing particle-laden flow models.

  13. Particle motion in fluidised beds

    International Nuclear Information System (INIS)

    Stein, M.G.

    1999-07-01

    Gas fluidised beds are important components in many process industries, e.g. coal combustors and granulators, but not much is known about the movement of the solids. Positron Emission Particle Tracking (PEPT) enables the movement of a single, radioactive tracer particle to be followed rapidly and faithfully. Experiments were carried out in columns sized between 70 and 240mm. diameter, operating in the bubbling regime at ambient process conditions using particles of group B and D (Geldart Classification). Particle motion was tracked and the data applied to models for particle movement at the gas distributor as well as close to other surfaces and to models for particle circulation in beds of cohesive particles. In the light of these data, models for particle and bubble interaction, particle circulation, segregation, attrition, erosion, heat transfer and fluidised bed scale-up rules were reassessed. Particle motion is directly caused by bubble motion, and their velocities were found to be equal for particles travelling in a bubble. PEPT enables particle circulation to be measured, giving a more accurate correlation for future predictions. Particle motion follows the scale-up rules based on similarities of the bubble motion in the bed. A new group of parameters was identified controlling the amount of attrition in fluidised beds and a new model to predict attrition is proposed. (author)

  14. Clinical physiology of bed rest

    Science.gov (United States)

    Greenleaf, John E.

    1993-01-01

    Maintenance of optimal health in humans requires the proper balance between exercise, rest, and sleep as well as time in the upright position. About one-third of a lifetime is spent sleeping; and it is no coincidence that sleeping is performed in the horizontal position, the position in which gravitational influence on the body is minimal. Although enforced bed rest is necessary for the treatment of some ailments, in some cases it has probably been used unwisely. In addition to the lower hydrostatic pressure with the normally dependent regions of the cardiovascular system, body fuid compartments during bed rest in the horizontal body position, and virtual elimination of compression on the long bones of the skeletal system during bed rest (hypogravia), there is often reduction in energy metabolism due to the relative confinement (hypodynamia) and alteration of ambulatory circadian variations in metabolism, body temperature, and many hormonal systems. If patients are also moved to unfamiliar surroundings, they probably experience some feelings of anxiety and some sociopsychological problems. Adaptive physiological responses during bed rest are normal for that environment. They are attempts by the body to reduce unnecessary energy expenditure, to optimize its function, and to enhance its survival potential. Many of the deconditioning responses begin within the first day or two of bed rest; these early responses have prompted physicians to insist upon early resumption of the upright posture and ambulation of bedridden patients.

  15. Radial voidage variation in fixed beds of fuel wood pellets

    International Nuclear Information System (INIS)

    Hamel, Stefan; Krumm, Wolfgang

    2012-01-01

    Fixed beds of fuel wood are commonly found in numerous processes: storage and transportation, drying and thermal conversion such as combustion or gasification. Pellets in particular are mostly used as fuel for domestic heating boilers. The characterization of spatial voidage distribution is of great importance for flow and reactor modelling. The present study focuses on the radial porosity variations of cylindrical beds of commercially available wood pellets. The experimental procedure is based on the classical technique of consolidating packed beds with a resin. The radial voidage distribution of three different cylindrical beds is determined by image analysis of sections of the solidified packing. The results are discussed and summarized in a mathematical expression correlating the radial voidage distribution depending on packing core porosity and dimensionless distance from the tube wall. -- Highlights: ► Packing characteristics for commercially available wood pellets were investigated. ► Radial porosity variations of cylindrical pellets beds were investigated. ► Epoxy resin consolidated packings were investigated by image analysis. ► Mathematical term for radial voidage distribution of pellet packing was derived.

  16. Deep space test bed for radiation studies

    International Nuclear Information System (INIS)

    The Deep Space Test-Bed (DSTB) Facility is designed to investigate the effects of galactic cosmic rays on crews and systems during missions to the Moon or Mars. To gain access to the interplanetary ionizing radiation environment the DSTB uses high-altitude polar balloon flights. The DSTB provides a platform for measurements to validate the radiation transport codes that are used by NASA to calculate the radiation environment within crewed space systems. It is also designed to support other exploration related investigations such as measuring the shielding effectiveness of candidate spacecraft and habitat materials, testing new radiation monitoring instrumentation, flight avionics and investigating the biological effects of deep space radiation. We describe the work completed thus far in the development of the DSTB and its current status

  17. Determination of pressure distribution in an aerated bed in a controlled pilot-scale compost reactor

    Energy Technology Data Exchange (ETDEWEB)

    Solowiej, P. [Warmia and Mazury Univ., Olsztyn (Poland)

    2010-07-01

    This study investigated the effectiveness of dealing with biological waste by composting. In particular, it examined the feasibility of recovering excess thermal energy produced in the process of composting biological waste in terms of mass and energy transport parameters required in the aerated compost bed. An experiment was performed in which a 100 dm{sup 3} adiabatic, leak-tight reactor equipped with a controlled aeration system was constructed to study the temperature and pressure distribution in the bed. Sensors were used to determine the amount and humidity of emitted gases under variable external physical conditions. The perforated bottom of the reactor allowed for bed aeration. As such, the humidity and heat were transported upwards, forced by the air pumped in and by natural convection. In terms of pressure distribution inside the composted and aerated bed, the study results showed that there were considerable differences in pressure for the selected places of the bed of the composted biological material. An increase in upwards pressure was observed in the heap throughout the experiment. Pressure differences in the same plane of the bed were also noted. The study results should facilitate the development of a model of mass and energy transport in a bed of composted material.

  18. Effects of Bed Forms and Large Protruding Grains on Near-Bed Flow Hydraulics in Low Relative Submergence Conditions

    Science.gov (United States)

    Monsalve, Angel; Yager, Elowyn M.; Schmeeckle, Mark W.

    2017-10-01

    In mountain rivers, bed forms, large relatively immobile grains, and bed texture and topographic variability can significantly alter local and reach-averaged flow characteristics. The low relative submergence of large immobile grains causes highly three-dimensional flow fields that may not be represented by traditional shear stress, flow velocity, and turbulence intensity equations. To explore the influence of large protruding grains and bed forms on flow properties, we conducted a set of experiments in which we varied the relative submergence while holding the sediment transport capacity and upstream sediment supply constant. Flow and bed measurements were conducted at the beginning and end of each experiment to account for the absence or presence of bed forms, respectively. Detailed information on the flow was obtained by combining our measurements with a 3-D numerical model. Commonly used velocity profile equations only performed well at the reach scale when shallow flow effects and the roughness length of the relatively mobile sediment were considered. However, at the local scale large deviations from these profiles were observed and simple methods to estimate the spatial distribution of near-bed shear stresses are likely to be inaccurate. Zones of high turbulent kinetic energy occurred near the water surface and were largely controlled by the immobile grains and plunging flow. The reach-averaged shear stress did not correlate to depth or slope, as commonly assumed, but instead was controlled by the relative boulder submergence and degree of plunging flow. For accurate flow predictions in mountain rivers, the effects of bed forms and large boulders must be considered.

  19. Particle Bed Reactor scaling relationships

    International Nuclear Information System (INIS)

    Slovik, G.; Araj, K.; Horn, F.L.; Ludewig, H.; Benenati, R.

    1987-01-01

    Scaling relationships for Particle Bed Reactors (PBRs) are discussed. The particular applications are short duration systems, i.e., for propulsion or burst power. Particle Bed Reactors can use a wide selection of different moderators and reflectors and be designed for such a wide range of power and bed power densities. Additional design considerations include the effect of varying the number of fuel elements, outlet Mach number in hot gas channel, etc. All of these variables and options result in a wide range of reactor weights and performance. Extremely light weight reactors (approximately 1 kg/MW) are possible with the appropriate choice of moderator/reflector and power density. Such systems are very attractive for propulsion systems where parasitic weight has to be minimized

  20. Fluidized-bed nuclear reactor

    International Nuclear Information System (INIS)

    Grimmett, E.S.; Kunze, J.F.

    1975-01-01

    A reactor vessel containing a fluidized-bed region of particulate material including both a neutron-moderating and a fertile substance is described. A gas flow including fissile material passes through the vessel at a sufficient rate to fluidize the particulate material and at a sufficient density to support a thermal fission reaction within the fluidized-bed region. The high-temperature portion of a heat transfer system is located within the fluidized-bed region of the reactor vessel in direct contact with the fluidized particles. Heat released by fission is thereby transferred at an enhanced rate to a coolant circulating within the heat transfer system. Fission products are continuously removed from the gas flow and supplemental fissile material added during the reactor operation. (U.S.)

  1. Quantifying the contribution of Long-Range Transport to PM, NOx, and SO2 loadings at a suburban site in the North-Western Indo Gangetic Basin

    Science.gov (United States)

    Pawar, Harshita; Sachan, Himanshu; Garg, Saryu; Arya, Ruhani; Singh, Nitin Kumar; Sinha, Baerbel; Sinha, Vinayak

    2013-04-01

    We investigate the climatology of air masses arriving at the IISER Mohali Atmospheric Chemistry facility (30.67°N, 76.73°E; 310 m amsl) through 3-day backtrajectories arriving at 20 m above ground level for the period August 2011-November 2012. IISER Mohali is a suburban site in the North-Western Indo Gangetic Basin. The trajectories are computed in ensemble mode twice daily with an arrival time of 2:30 pm local time (daytime) and 4:30 am local time (nighttime) using the HYSPLIT 4 model with the National Oceanic and Atmospheric Administration's GDAS file as meterological input data. Due to the close proximity of the site to the Himalayan mountain range the trajectory output is found to be very sensitive to the models input data. IISER Air Quality station is located in the IGB at an altitude of 310 m amsl approximately 20 km south west of the Shivalik hills, but the model terrain height for the site in the ensemble run output varies between 200 m amsl and 3500 m amsl for the GDAS dataset and 200 m amsl to 5000 m amsl for the reanalysis dataset. We conclude that the GDAS dataset performs better than than reanalysis dataset for our site and selected only those trajectories from the trajectory ensemble for cluster analysis, for which the terrain height in the model output was 400 m amsl for Shimla (a site located at an altitude of 1000 m amsl in the mountains 60 km north east of Mohali). We subjected the trajectories to hierarchical, and non-hierarchical (K-means) clustering and found that the air mass transport to our station can be characterised by 10 distinct airflow patterns; 3 of which occur only during the monsoon season. For pre-monsoon season (March-June), post-monsoon season (Sept-Nov) and winter season (Dec-Feb), air mass transport to our site is predominantly from the west. Direct transport of north westerly air masses to our site is subdivided into three clusters (slow, medium and rapid) while other clusters are attributed to south westerly air currents

  2. Better backs by better beds?

    DEFF Research Database (Denmark)

    Bergholdt, Kim; Fabricius, Rasmus N; Bendix, Tom

    2008-01-01

    STUDY DESIGN: A "randomized"/stratified, single-blinded, parallel-group study. OBJECTIVE.: To evaluate 3 structurally different mattresses relative influence on patients with chronic low back pain (CLBP). SUMMARY OF BACKGROUND DATA: In several advertisements, it is proclaimed that certain...... using the probably most relevant "worst case" data. There were no relevant difference between the effects of the water bed and the foam bed. CONCLUSION: The Waterbed and foam mattress' did influence back symptoms, function and sleep more positively as apposed to the hard mattress, but the differences...

  3. A balanced treatment of secondary currents, turbulence and dispersion in a depth-integrated hydrodynamic and bed deformation model for channel bends

    Science.gov (United States)

    Begnudelli, Lorenzo; Valiani, Alessandro; Sanders, Brett F.

    2010-01-01

    This work deals with the formulation and numerical implementation of a two-dimensional mathematical and numerical model describing open channel hydrodynamics, sediment and/or scalar transport and riverbed evolution in curved channels. It is shown that a well balanced 2D model can predict flow features, sediment and scalar concentration, and bed elevation with an accuracy that is suitable for practical river engineering. The term "balanced" implies that important physical processes are modeled with a similar degree of complexity and exhaustiveness. The starting point of the model formulation is the assumption of self-similarity of vertical velocity profiles (horizontal velocities in the longitudinal and transverse directions), that are scaled by shear velocity and streamline curvature, both resolved by the model. The former is scaled by a bed-resistance coefficient that must be estimated or calibrated - as usual - on a application-specific basis, and the latter is computed by a new, grid-based but grid orientation independent, scheme that acts on the discrete solution. All processes, including bottom shear, momentum dispersion, scalar dispersion, turbulent diffusion, bed load, and suspended load, are modeled using physically based, averaged values of empirical or semi-empirical constants, and consistently with the assumed velocity profiles (and bed-generated turbulence). Bed deformation modeling can be implemented with either an equilibrium or non-equilibrium formulation of the Exner equation, depending on the adaptation length scale, which must be taken under consideration if significantly larger than the length scale of the spatial discretization. The governing equations are solved by high-resolution, unstructured-grid Godunov method, which is elsewhere tested and shown to be reliable and second-order accurate. Application of the model to laboratory test cases, using standard parameter values and previously reported bed-resistance coefficients, gives results

  4. Co-transport and co-combustion. An alternative to separate collecting of biological waste?; Co-Transport und Co-Verwertung. Eine Alternative zur getrennten Bioabfallsammlung?

    Energy Technology Data Exchange (ETDEWEB)

    Kegebein, J.; Hoffmann, E.; Hahn, H.H. [Karlsruhe Univ. (T.H.) (Germany). Inst. fuer Siedlungswasserwirtschaft

    2001-06-01

    As an alternative or supplementary to the separate bio-waste collection system the transport of ground organic kitchen waste along with wastewater in sewer systems has been investigated and reuse processes are discussed. Organic kitchen waste has been ground with a commercial food-waste-grinder, the suspensions were characterized with respect to transport, particle size and settling velocity distribution. Approximately 1/3 of the solids were solbilized due to the grinding-process. Residual non-solubilized solids have been transported evenly as bed load and as suspended solids within a half-scale flow channel at low flow velocities. Organic food waste may be utilized as carbon-source for enhanced biological nutrient removal or as substrate for anaerobic digestion and bio-gas production or as a combination of both reuse path-ways. (orig.)

  5. Conceptual evaluation of hybrid energy system comprising wind-biomass-nuclear plants for load balancing and for production of renewable synthetic transport fuels

    International Nuclear Information System (INIS)

    Carlsson, Johan; Purvins, Arturs; Papaioannou, Ioulia T.; Shropshire, David; Cherry, Robert S.

    2014-01-01

    Future energy systems will increasingly need to integrate variable renewable energy in order to reduce greenhouse gas emissions from power production. Addressing this trend the present paper studies how a hybrid energy systems comprising aggregated wind farms, a biomass processing plant, and a nuclear cogeneration plant could support high renewable energy penetration. The hybrid energy system operates so that its electrical output tends to meet demand. This is achieved mainly through altering the heat-to-power ratio of the nuclear reactor and by using excess electricity for hydrogen production through electrolysis. Hybrid energy systems with biomass treatment processes, i.e. drying, torrefaction, pyrolysis and synthetic fuel production were evaluated. It was shown that the studied hybrid energy system comprising a 1 GWe wind farm and a 347 MWe nuclear reactor could closely follow the power demand profile with a standard deviation of 34 MWe. In addition, on average 600 m 3 of bio-gasoline and 750 m 3 bio-diesel are produced daily. The reduction of greenhouse gas emissions of up to 4.4 MtCO 2 eq annually compared to power generation and transport using conventional fossil fuel sources. (author)

  6. A review of a method for dynamic load distribution, dynamical modeling, and explicit internal force control when two manipulators mutually lift and transport a rigid body object

    Energy Technology Data Exchange (ETDEWEB)

    Unseren, M.A.

    1997-04-20

    The paper reviews a method for modeling and controlling two serial link manipulators which mutually lift and transport a rigid body object in a three dimensional workspace. A new vector variable is introduced which parameterizes the internal contact force controlled degrees of freedom. A technique for dynamically distributing the payload between the manipulators is suggested which yields a family of solutions for the contact forces and torques the manipulators impart to the object. A set of rigid body kinematic constraints which restrict the values of the joint velocities of both manipulators is derived. A rigid body dynamical model for the closed chain system is first developed in the joint space. The model is obtained by generalizing the previous methods for deriving the model. The joint velocity and acceleration variables in the model are expressed in terms of independent pseudovariables. The pseudospace model is transformed to obtain reduced order equations of motion and a separate set of equations governing the internal components of the contact forces and torques. A theoretic control architecture is suggested which explicitly decouples the two sets of equations comprising the model. The controller enables the designer to develop independent, non-interacting control laws for the position control and internal force control of the system.

  7. Performance Assessment of a Generic Repository in Bedded Salt for DOE-Managed Nuclear Waste

    Science.gov (United States)

    Stein, E. R.; Sevougian, S. D.; Hammond, G. E.; Frederick, J. M.; Mariner, P. E.

    2016-12-01

    A mined repository in salt is one of the concepts under consideration for disposal of DOE-managed defense-related spent nuclear fuel (SNF) and high level waste (HLW). Bedded salt is a favorable medium for disposal of nuclear waste due to its low permeability, high thermal conductivity, and ability to self-heal. Sandia's Generic Disposal System Analysis framework is used to assess the ability of a generic repository in bedded salt to isolate radionuclides from the biosphere. The performance assessment considers multiple waste types of varying thermal load and radionuclide inventory, the engineered barrier system comprising the waste packages, backfill, and emplacement drifts, and the natural barrier system formed by a bedded salt deposit and the overlying sedimentary sequence (including an aquifer). The model simulates disposal of nearly the entire inventory of DOE-managed, defense-related SNF (excluding Naval SNF) and HLW in a half-symmetry domain containing approximately 6 million grid cells. Grid refinement captures the detail of 25,200 individual waste packages in 180 disposal panels, associated access halls, and 4 shafts connecting the land surface to the repository. Equations describing coupled heat and fluid flow and reactive transport are solved numerically with PFLOTRAN, a massively parallel flow and transport code. Simulated processes include heat conduction and convection, waste package failure, waste form dissolution, radioactive decay and ingrowth, sorption, solubility limits, advection, dispersion, and diffusion. Simulations are run to 1 million years, and radionuclide concentrations are observed within an aquifer at a point approximately 4 kilometers downgradient of the repository. The software package DAKOTA is used to sample likely ranges of input parameters including waste form dissolution rates and properties of engineered and natural materials in order to quantify uncertainty in predicted concentrations and sensitivity to input parameters. Sandia

  8. Stress responses of juvenile matrinxã (Brycon amazonicus after transport in a closed system under different loading densities Respostas de estresse de matrinxã (Brycon amazonicus juvenil após transporte em sistema fechado sob diferentes densidades de carga

    Directory of Open Access Journals (Sweden)

    Janessa Sampaio de Abreu

    2008-08-01

    Full Text Available Optimum loading density for the transport of matrinxã juveniles was investigated in a closed system with plastic bags. Transport was conducted for 4 h with fish (23.5± 0.4g and 11.6 (0.08cm starved for 24h at loading densities of 83g L-1 (D1, 125g L-1 (D2, 168g L-1 (D3 and 206g L-1 (D4. Fish were sampled before transport (BT, after transport (AT and 24h AT. The water quality was monitored before capturing fish in depuration tanks, after transport in plastic bags and in recovery tanks. Water oxygen decreased to values below 4mg L-1 in D2, D3 and D4, temperature was around 32°C, pH 6.5-6.78, total ammonia 1.09-1.7mg L-1, un-ionized ammonia 3.58-9.33x10³mg L-1 and alkalinity 134-165mg CaCO3 L-1. Blood cortisol and glucose concentrations increased in fish of all densities AT and recovered the BT levels 24h after arrival. Osmolality did not change AT but increased 24h AT in fish of all densities whereas plasma chloride decreased inversely to the loading densities after the procedure. Hematocrit decreased 24h AT in fish of all densities but no differences were verified in the number of erythrocytes. No mortality was registered in any treatment during the next week after transport. Matrinxã demonstrated to be a crowding tolerant-species in transport operations besides tolerating low levels of oxygen in the water.Neste estudo, foram investigadas as densidades de carga adequadas para transporte de matrinxãs juvenis em sistema fechado com sacos plásticos. O transporte de 4h foi feito com peixes (23,5±0,4g; 11,6 (0,08cm em jejum por 24h, em densidades de 83g L-1 (D1, 125g L-1 (D2, 168g L-1 (D3 e 206g L-1 (D4. Os peixes foram amostrados antes do transporte (AT, logo após o transporte (chegada (DT e 24h depois. A qualidade da água foi monitorada antes da captura dos peixes nos tanques de depuração, após o transporte nos sacos plásticos e nos tanques de recuperação. O oxigênio da água diminuiu para valores inferiores a 4mg L-1 em D2, D3 e D4

  9. Apparatus and process for controlling fluidized beds

    Science.gov (United States)

    Rehmat, Amirali G.; Patel, Jitendra G.

    1985-10-01

    An apparatus and process for control and maintenance of fluidized beds under non-steady state conditions. An ash removal conduit is provided for removing solid particulates from a fluidized bed separate from an ash discharge conduit in the lower portion of the grate supporting such a bed. The apparatus and process of this invention is particularly suitable for use in ash agglomerating fluidized beds and provides control of the fluidized bed before ash agglomeration is initiated and during upset conditions resulting in stable, sinter-free fluidized bed maintenance.

  10. Conceptual Site Model for Newark Bay—Hydrodynamics and Sediment Transport

    Directory of Open Access Journals (Sweden)

    Parmeshwar L. Shrestha

    2014-02-01

    Full Text Available A conceptual site model (CSM has been developed for the Newark Bay Study Area (NBSA as part of the Remedial Investigation/Feasibility Study (RI/FS for this New Jersey site. The CSM is an evolving document that describes the influence of physical, chemical and biological processes on contaminant fate and transport. The CSM is initiated at the start of a project, updated during site activities, and used to inform sampling and remediation planning. This paper describes the hydrodynamic and sediment transport components of the CSM for the NBSA. Hydrodynamic processes are influenced by freshwater inflows, astronomical forcing through two tidal straits, meteorological conditions, and anthropogenic activities such as navigational dredging. Sediment dynamics are driven by hydrodynamics, waves, sediment loading from freshwater sources and the tidal straits, sediment size gradation, sediment bed properties, and particle-to-particle interactions. Cohesive sediment transport is governed by advection, dispersion, aggregation, settling, consolidation, and erosion. Noncohesive sediment transport is governed by advection, dispersion, settling, armoring, and transport in suspension and along the bed. The CSM will inform the development and application of a numerical model that accounts for all key variables to adequately describe the NBSA’s historical, current, and future physical conditions.

  11. Physiology Of Prolonged Bed Rest

    Science.gov (United States)

    Greenleaf, John E.

    1991-01-01

    Report describes physiological effects of prolonged bed rest. Rest for periods of 24 hours or longer deconditions body to some extent; healing proceeds simultaneously with deconditioning. Report provides details on shifts in fluid electrolytes and loss of lean body mass, which comprises everything in body besides fat - that is, water, muscle, and bone. Based on published research.

  12. Accident resistant transport container

    Science.gov (United States)

    Anderson, J.A.; Cole, K.K.

    The invention relates to a container for the safe air transport of plutonium having several intermediate wood layers and a load spreader intermediate an inner container and an outer shell for mitigation of shock during a hypothetical accident.

  13. Influence of large wood on channel hydraulics, sediment (dis-)connectivity and channel morphology in a medium-sized mixed-load Austrian stream

    Science.gov (United States)

    Schuchardt, Anne; Pöppl, Ronald; Morche, David

    2017-04-01

    It is widely known that large wood (LW) in rivers alters channel hydraulics, channel morphology and sediment transport. Channel spanning LW can create blocking barriers, steps and dams which store sediment and organic material in small reservoirs for the lifetime of the damming structure. Otherwise, the breach of LW key logs and jams makes the long term stored sediment available for fluvial transport. However, detailed field measurements on the distribution of LW and its influence on hydraulic variables, channel morphology and (especially) sediment connectivity are still rare, thus further constituting the major aim of this study. The study was performed along the lower reaches ( 6 km) of the Fugnitz River, a mixed-load, medium-sized (catchment area 130 km2) single-thread perennial stream, located in the Bohemian Massif, Austria. The spatial distribution and characterization of LW (>1 m in length and >10 cm in diameter) was examined along the main stem via field mapping and dGPS measurements. Hydraulic channel parameters (e.g. channel gradient, cross-sectional profiles) and volumes of retained sediment were determined via field measurements, while channel morphology incl. indications of LW-induced geomorphic processes (e.g. bank undercutting, scouring) was obtained via geomorphic mapping. Flow characteristics and bed load transport rates were measured using an Ott-Nautilus and a portable Helley-Smith bed load sampler during different water stages. Additionally, bed sediment textures were examined by performing pebble count analyses. In-channel LW accumulations (total volume of 588 m3) were primarily observed in meandering river reaches as well as in reaches with steep hillslopes. 36% of all LW accumulations were classified as dams, steps or deflectors altering flow conditions or creating backwater areas decreasing sediment connectivity. Highest volumes of sediment storage (total volume of 26 m3) have been primarily recorded at locations where bank erosion processes

  14. A 2D hydrodynamic-sedimentological model for gravel bed rivers. Part II, Case study: the Brenta River in Italy

    Directory of Open Access Journals (Sweden)

    Gabriel Kaless

    2013-09-01

    Full Text Available A 2D depth average model has been used to simulate water and sediment flow in the Brenta River so as to interpret channel changes and to assess model predictive capabilities. The Brenta River is a gravel bed river located in Northern Italy. The study reach is 1400 long and has a mean slope of 0.0056. High resolution digital terrain models has been produced combining laser imaging detection and ranging data with colour bathymetry techniques. Extensive field sedimentological surveys have been also carried out for surface and subsurface material. The data were loaded in the model and the passage of a high intense flood (R.I. > 9 years was simulated. The model was run under the hypothesis of a substantial equilibrium between sediment input and transport capacity. In this way, the model results were considered as a reference condition, and the potential trend of the reach was assessed. Low-frequency floods (R.I. » 1.5 years are expected to produce negligible changes in the channel while high floods may focalize erosion on banks instead than on channel bed. Furthermore, the model predicts well the location of erosion and siltation areas and the results promote its application to other reaches of the Brenta River in order to assess their stability and medium-term evolution.

  15. Carbohydrate Loading.

    Science.gov (United States)

    Csernus, Marilyn

    Carbohydrate loading is a frequently used technique to improve performance by altering an athlete's diet. The objective is to increase glycogen stored in muscles for use in prolonged strenuous exercise. For two to three days, the athlete consumes a diet that is low in carbohydrates and high in fat and protein while continuing to exercise and…

  16. Design and simulation of a circulating fluidized bed to clean the products of biomass gasification

    Energy Technology Data Exchange (ETDEWEB)

    Uchoa Neto, Moises; Carvalho, Yuri de Araujo [Dept. de Engenharia Mecanica. Faculdade de Tecnologia. Universidade de Brasilia, DF (Brazil); Oliveira, Taygoara Felamingo de; Barcelos, Manuel [Faculdade do Gama. Universidade de Brasilia, Gama, DF (Brazil)], e-mail: taygoara@unb.br

    2010-07-01

    The main goal of this work is to design a workbench circulating fluidized bed to study the cracking of tar in gases from the processes of biomass gasification. For this, a design methodology based on analytical results and empirical correlations for fluidized beds was employed. In parallel, a numerical code of open source technology (MFIX) for the solution of the transport equations of the multiphase flow in the column of a fluidized bed was used to give support to the choice of the design elements. The whole project of the workbench fluidized bed was completely developed, whose operation parameters such as bed geometry, gas velocity, circulating ratio and void fraction characterize a fast fluidization process. A preliminary mesh convergence study was executed with the numerical tool, that was validated comparing with analytical results. Among the most important results, the code computed the predicted value for the minimum fluidization. (author)

  17. Sand transport in the lower Mississippi River does not yield to dams: Applications for building deltaic land in Louisiana

    Science.gov (United States)

    Nittrouer, J. A.; Viparelli, E.

    2013-12-01

    The Mississippi Delta is presently undergoing a catastrophic drowning, whereby 5000 km2 of low-lying wetlands have converted to open water. This land loss is primarily the result of: a) relative sea-level rise, occurring due to the combined effect of rapid subsidence associated with subsurface fluids extraction and eustatic rise; b) leveeing and damming of the river and its tributaries, which restricts sediment delivery to and dispersal within the delta; and c) severe excavation of the delta for navigation channels. It has been argued that continued net land loss of the Mississippi Delta is inevitable due to declining measured total (sand and mud) suspended sediment loads over the past 6 decades. However, recent research has documented that the key to delta growth is deposition of sand, which accounts for ~50-70% of modern and ancient (up to 9 m.a.) Mississippi Delta deposits, but comprises only ~20% of the sampled portion of the total load. Here we present new analysis of existing data to show that sand transport has not diminished since dam construction. Furthermore, we produce a numerical model based on the mass balance of bed material loads over the lower 1600 km of the Mississippi River to show that mining of sand from the channel bed continues to replenish downstream sand loads. For example, our model results indicate that it requires approximately 240 years for a reduced sand load to reach the delta apex. Furthermore, our calculations indicate that sand load at the delta apex is reduced by a noticeable amount (17%) only after about 600 years. We also show how channel bed elevations are predicted to change over the lower 1600 km of the river channel due to channel mining. Channel-bed degradation is greatest at the upstream end of the study reach and decreases downstream. After 300 years the wave of significant degradation has just passed ~800 km downstream, or roughly half of our model domain. These results are in contrast to the measurements which concern

  18. Coevolution of bed surface patchiness and channel morphology: 1. Mechanisms of forced patch formation

    Science.gov (United States)

    Nelson, Peter A.; McDonald, Richard R.; Nelson, Jonathan M.; Dietrich, William E.

    2015-01-01

    Riverbeds frequently display a spatial structure where the sediment mixture composing the channel bed has been sorted into discrete patches of similar grain size. Even though patches are a fundamental feature in gravel bed rivers, we have little understanding of how patches form, evolve, and interact. Here we present a two-dimensional morphodynamic model that is used to examine in greater detail the mechanisms responsible for the development of forced bed surface patches and the coevolution of bed morphology and bed surface patchiness. The model computes the depth-averaged channel hydrodynamics, mixed-grain-size sediment transport, and bed evolution by coupling the river morphodynamic model Flow and Sediment Transport with Morphological Evolution of Channels (FaSTMECH) with a transport relation for gravel mixtures and the mixed-grain-size Exner equation using the active layer assumption. To test the model, we use it to simulate a flume experiment in which the bed developed a sequence of alternate bars and temporally and spatially persistent forced patches with a general pattern of coarse bar tops and fine pools. Cross-stream sediment flux causes sediment to be exported off of bars and imported into pools at a rate that balances downstream gradients in the streamwise sediment transport rate, allowing quasi-steady bar-pool topography to persist. The relative importance of lateral gravitational forces on the cross-stream component of sediment transport is a primary control on the amplitude of the bars. Because boundary shear stress declines as flow shoals over the bars, the lateral sediment transport is increasingly size selective and leads to the development of coarse bar tops and fine pools.

  19. Stable-channel design in gravel-bed rivers

    Science.gov (United States)

    Griffiths, George A.

    1981-07-01

    Regime relations are derived for more or less straight, stable, symmetrical, wide reaches of coarse gravel-bed rivers having low rates of bedload transport at bankfull flow conditions. The relations are combined to express channel width as a function of median size of bed pavement, energy slope and bankfull water discharge, for sediment of constant specific gravity. This stable-channel design equation, together with three others of similar form in current usage, is tested for accuracy of channel width prediction with 60 field data sets from appropriate gravel-bed river reaches. The minimum mean deviation of predicted width, from the actual width prescribed in each data set, was 160%, with a standard deviation of 430%. A dimensionless stability index, defined in terms of the above parameters, is deduced and shown to be remarkably constant in value at stable reach sections on particular gravel-bed rivers, and for rivers within a single watershed. Employment of this index will result in a substantial improvement in the accuracy of stable-channel design. The range of application of the stability index method is increased by a combination with an empirical equation that predicts median bed-pavement size, from given flow conditions over gravel-bed material having a known initial sediment size distribution. An example of the suggested design procedure, following from this combination, is given for an existing unstable river-diversion channel. Some recommendations are made concerning the identification of stable river reaches and the determination of the requisite sediment parameters for design.

  20. Textiles wastewater treatment using anoxic filter bed and biological wriggle bed-ozone biological aerated filter.

    Science.gov (United States)

    Fu, Zhimin; Zhang, Yugao; Wang, Xiaojun

    2011-02-01

    In this study, the performance of the anoxic filter bed and biological wriggle bed-ozone biological aerated filter (AFB-BWB-O(3)-BAF) process treating real textile dyeing wastewater was investigated. After more than 2 month process operation, the average effluent COD concentration of the AFB, BWB, O(3)-BAF were 704.8 mg/L, 294.6 mg/L and 128.8 mg/L, with HRT being 8.1-7.7h, 9.2h and 5.45 h, respectively. Results showed that the effluent COD concentration of the AFB decreased with new carriers added and the average removal COD efficiency was 20.2%. During operation conditions, HRT of the BWB and O(3)-BAF was increased, resulting in a decrease in the effluent COD concentration. However, on increasing the HRT, the COD reduction capability expressed by the unit carrier COD removal loading of the BWB reactor increased, while that of the O(3)-BAF reactor decreased. This study is a beneficial attempt to utilize the AFB-BWB-O(3)-BAF combine process for textile wastewater treatment. Copyright © 2010 Elsevier Ltd. All rights reserved.

  1. Protecting Your Home from Bed Bugs

    Science.gov (United States)

    ... your home: Inspect the luggage rack in your hotel room for bed bugs. Check secondhand furniture, beds, ... Grants January 19, 2017 Web Snapshot No FEAR Act Data Privacy Privacy and Security Notice Connect. Data. ...

  2. Videos, Webinars, Blogs Related to Bed Bugs

    Science.gov (United States)

    These tools provide practical insight on issues such as integrated pest management (IPM) for schools, bed bug bites, how carpet beetles can help, bed bugs as hitchhikers, and preventing and controlling infestations.

  3. EPA-Registered Bed Bug Products

    Science.gov (United States)

    ... treat your bed bug infestation. Foggers and bug bombs should not be used as the only method ... effective but take some time to kill the population); or Bed bugs’ becoming resistant to a specific ...

  4. RANS-based simulation of turbulent wave boundary layer and sheet-flow sediment transport processes

    DEFF Research Database (Denmark)

    Fuhrman, David R.; Schløer, Signe; Sterner, Johanna

    2013-01-01

    with bed and suspended load descriptions, the latter based on an unsteady turbulent-diffusion equation, for simulation of sheet-flow sediment transport processes. In addition to standard features common within such RANS-based approaches, the present model includes: (1) hindered settling velocities at high...... of a number of local factors important within cross-shore wave boundary layer and sediment transport dynamics. The hydrodynamic model is validated for both hydraulically smooth and rough conditions, based on wave friction factor diagrams and boundary layer streaming profiles, with the results in excellent...... agreement with experimental and/or previous numerical work. The sediment transport model is likewise validated against oscillatory tunnel experiments involving both velocity-skewed and acceleration-skewed flows, as well as against measurements beneath real progressive waves.Model capabilities are exploited...

  5. Effects of colloids on metal transport in a river receiving acid mine drainage, upper Arkansas River, Colorado, U.S.A.

    Science.gov (United States)

    Kimball, Briant A.

    1995-01-01

    Inflows of metal-rich, acidic water that drain from mine dumps and tailings piles in the Leadville, Colorado, area enter the non-acidic water in the upper Arkansas River. Hydrous iron oxides precipitate as colloids and move downstream in suspension, particularly downstream from California Gulch, which has been the major source of metal loads. The colloids influence the concentrations of metals dissolved in the water and the concentrations in bed sediments. To determine the role of colloids, samples of water, colloids, and fine-grained bed sediment were obtained at stream-gaging sites on the upper Arkansas River and at the mouths of major tributaries over a 250-km reach. Dissolved and colloidal metal concentrations in the water column were operationally defined using tangential-flow filtration through 0.001-pm membranes to separate the water and the colloids. Surface-extractable and total bed sediment metal concentrations were obtained on the colloids, and bed sediments occurred just downstream from California Gulch. Iron dominated the colloid composition, but substantial concentrations of As, Cd, Cu, Mn, Pb, and Zn also occurred in the colloidal solids. The colloidal load decreased by one half in the first 50 km downstream from the mining inflows due to sedimentation of aggregated colloids to the streambed. Nevertheless, a substantial load of colloids was transported through the entire study reach to Pueblo Reservoir. Dissolved metals were dominated by Mn and Zn, and their concentrations remained relatively high throughout the 250-km reach. The composition of extractable and total metals in bed sediment for several kilometers downstream from California Gulch is similar to the composition of the colloids that settle to the bed. Substantial concentrations of Mn and Zn were extractable, which is consistent with sediment-water chemical reaction. Concentrations of Cd, Pb, and Zn in bed sediment clearly result from the influence of mining near Leadville. Concentrations

  6. Chemical characterisation and source apportionment of PM1 during massive loading at an urban location in Indo-Gangetic Plain: impact of local sources and long-range transport

    Directory of Open Access Journals (Sweden)

    Prashant Rajput

    2016-07-01

    Full Text Available This study assesses temporal variability and source contributions of PM1 (particles with aerodynamic diameter ≤ 1.0 µm samples (n=51; November 2009–February 2010 from an urban location at Kanpur (26.30°N; 80.13°E; 142 m above mean sea-level in the Indo-Gangetic Plain (IGP. A study period from November to February is preferred owing to massive loading of particulate matter in entire IGP. PM1 varies from 18 to 348 (Avg±SD: 113±72 µg m−3 in this study. A total of 11 trace metals, five major elements and four water-soluble inorganic species (WSIS have been measured. Mass fraction of total metals (∑metals=trace+major centres at 18±14 %, of which nearly 15 % is contributed by major elements. Furthermore, ∑WSIS contributes about 26 % to PM1 mass concentration. Abundance pattern among assessed WSIS in this study follows the order: ≈> > Cl−. The K-to-PM1 mass fraction (Avg: 2 % in conjunction with air-mass back trajectories (AMBT indicates that the prevailing north-westerly winds transport biomass burning derived pollutants from upwind IGP. A recent version of positive matrix factorisation (PMF 5.0 has been utilised to quantify the contribution of fine-mode aerosols from various sources. The contribution from each source is highly variable and shows a strong dependence on AMBT. Events with predominant contribution from biomass burning emission (>70 % indicate origin of air-masses from source region upwind in IGP. One of the most interesting features of our study relates to the observation that secondary aerosols (contributing as high as ~60 % to PM1 loading are predominantly derived from stationary combustion sources (/ ratio: 0.30±0.23. Thus, our study highlights a high concentration of PM1 loading and atmospheric fog prevalent during wintertime can have a severe impact on atmospheric chemistry in the air-shed of IGP.

  7. An old paper revisited: "a mathematical model of carbohydrate energy metabolism. Interaction between glycolysis, the Krebs cycle and the H-transporting shuttles at varying ATPases load" by V.V. Dynnik, R. Heinrich and E.E. Sel'kov.

    Science.gov (United States)

    Nazaret, Christine; Mazat, Jean-Pierre

    2008-06-07

    We revisit an old Russian paper by V.V. Dynnik, R. Heinrich and E.E. Sel'kov (1980a,b) describing: "A mathematical model of carbohydrate energy metabolism. Interaction between glycolysis, the Krebs cycle and the H-transporting shuttles at varying ATPases load". We analyse the model mathematically and calculate the control coefficients as a function of ATPase loads. We also evaluate the structure of the metabolic network in terms of elementary flux modes. We show how this model can respond to an ATPase load as well as to the glucose supply. We also show how this simple model can help in understanding the articulation between the major blocks of energetic metabolism, i.e. glycolysis, the Krebs cycle and the H-transporting shuttles.

  8. Fluidization quality analyzer for fluidized beds

    Science.gov (United States)

    Daw, C.S.; Hawk, J.A.

    1995-07-25

    A control loop and fluidization quality analyzer for a fluidized bed utilizes time varying pressure drop measurements. A fast-response pressure transducer measures the overall bed pressure drop, or over some segment of the bed, and the pressure drop signal is processed to produce an output voltage which changes with the degree of fluidization turbulence. 9 figs.

  9. Designing a CR Test bed

    DEFF Research Database (Denmark)

    Cattoni, Andrea Fabio; Buthler, Jakob Lindbjerg; Tonelli, Oscar

    2014-01-01

    with their own set up, since the potential costs and efforts could not pay back in term of expected research results. Software Defined Radio solutions offer an easy way to communication researchers for the development of customized research test beds. While several hardware products are commercially available......Research on intelligent and reconfigurable wireless systems is in continuous evolution. Nevertheless, in order to fix some keystones, more and more researchers are entering the idea of research-oriented test beds. Unfortunately, it is very difficult for a wide number of research groups to start......, the software is most of the times open source and ready to use for third party users. Even though the software solution developers claim complete easiness in the development of custom applications, in reality there are a number of practical hardware and software issues that research groups need to face, before...

  10. Review of acute cancer beds.

    LENUS (Irish Health Repository)

    Evans, D S

    2012-01-01

    A review of admissions to cancer services at University Hospital Galway (UHG) was undertaken to assess the appropriateness of hospital usage. All cancer specialty patients admitted from 26-28 May 2009 were reviewed (n = 82). Chi square tests, Exact tests, and One-way ANOVA were utilised to analyse key issues emerging from the data. Fifty (61%) were classified as emergencies. Twenty three (67%) occupied a designated cancer bed with 24 (30%) in outlying non-oncology wards. The mean length of stay was 29.3 days. Possible alternatives to admission were identified for 15 (19%) patients. There was no evidence of discharge planning for 50 (60%) admissions. There is considerable potential to make more appropriate utilisation of UHG for cancer patients, particularly in terms of reducing bed days and length of stay and the proportion of emergency cancer admissions, and further developing integrated systems of discharge planning.

  11. Device for measuring bed pressure

    Energy Technology Data Exchange (ETDEWEB)

    Gulin, B.M.; Chubar, V.G.

    1979-03-05

    The invention refers to studies in wells and is designed for piezomeasurements for the processes of undergrond leaching out associated with the movement of fluids of variable density to the productive beds. The purpose of he invention is to increase the accuracy of measurements of bed pressure by reducing the influence of changes of fluid density in the well. The goal is achieved because the device is equipped with a piezometric pipe arranged in the well and filled with liquid whose density is less than the density of the solution, and the transformer of the level is installed in the pipe. The pipe can have a throttle. A drawing and description of the proposed device are presented.

  12. THE BAUXITES AND JELAR - BEDS

    Directory of Open Access Journals (Sweden)

    Krešimir Sakač

    1993-12-01

    Full Text Available Minor bauxite deposits and occurrences were formed in technically disturbed environments in the middle part of the Adriatic geotectonic unit in Dinarides, contemporary with the clastic Jelar-beds in the Late Lutetian time. Uneven chemical composition of these Eocene bauxites, their sporadic occurrences in developed paleorelief as well as characteristic petrographic composition of the immediate overlying rocks point out at different genetical conditions (the paper is published in Croatian.

  13. Dynometer test bed (fact sheet)

    Energy Technology Data Exchange (ETDEWEB)

    O' Dell, K.

    2000-04-24

    The National Renewable Energy Laboratory's (NREL's) Dynamometer Test Bed is one of a kind. It offers wind industry engineers a unique opportunity to conduct lifetime endurance tests on a wide range of wind turbine drivetrains and gearboxes at various speeds, using low or high torque. By testing full-scale wind turbines, engineers from NREL and industry hope to understand the impact of various wind conditions with the goal of improving hardware design.

  14. Transport of sediments in Himalaya-Karakorum and its influence on hydropower plants; Sedimenttransportprozesse im Himalaya-Karakorum und ihre Bedeutung fuer Wasserkraftanlagen

    Energy Technology Data Exchange (ETDEWEB)

    Palt, S.M.

    2001-07-01

    In the present study the sediment transport processes in alpine mountain areas and their impact on hydropower development projects are investigated. The aim of the present work is to contribute to the understanding of the transport process system, which is characterized by high magnitude-low frequency - events, to ensure an appropriate layout of high head hydropower projects in mountain regions. The sediment transport in large areas in the macro scale is triggered by natural hazards, such as earthquakes, rock slides, earth movements, debris flows, glacial lake outbursts and floods. The basic principle of complex transport processes in this scale is described and explained on the example of the Himalaya-Karakorum-region. The sediment transport process in the smaller scale, so called meso scale, is investigated by means of extensive field measurements at river reaches of 16 different mountain rivers of a 80000 km{sup 2} large project area. The measurements include topographic survey works and measurements of discharge, bed load and suspended load. Since the conditions of mountain rivers in terms of size of bed material as well as available flow velocities can be considered as extreme, an appropriate bed load sampler named B-69 was developed, constructed and used in the field. Moreover the hydraulic as well as the sedimentological efficiency of the sampler was tested in the laboratory tests. Due to the nice performance of the bed load sampler B-69 at high flow velocities it might be useful for flood conditions in gravel-bed rivers in other parts of the world as well. Based on the results of the study the parameter of the river slope can be considered as the most important one for the characteristics of the morphology, the flow conditions, the bed stability as well as the bed load transport in steep mountain rivers. With increasing slope morphological structures in the longitudinal direction will develop from flat bed conditions. The so called step-pool-systems consist

  15. First results of the post-irradiation examination of the Ceramic Breeder materials from the Pebble Bed Assemblies Irradiation for the HCPB Blanket concept

    International Nuclear Information System (INIS)

    Hegeman, J.; Magielsen, A.J.; Peeters, M.; Stijkel, M.P.; Fokkens, J.H.; Laan, J.G. van der

    2006-01-01

    In the framework of developing the European Helium Cooled Pebble-Bed (HCPB) blanket an irradiation test of pebble-bed assemblies is performed in the HFR Petten. The experiment is focused on the thermo-mechanical behavior of the HCPB type breeder pebble-bed at DEMO representative levels of temperature and defined thermal-mechanical loads. To achieve representative conditions a section of the HCPB is simulated by EUROFER-97 cylinders with a horizontal bed of ceramic breeder pebbles sandwiched between two beryllium beds. Floating Eurofer-97 steel plates separate the pebble-beds. The structural integrity of the ceramic breeder materials is an issue for the design of the Helium Cooled Pebble Bed concept. Therefore the objective of the post irradiation examination is to study deformation of pebbles and the pebble beds and to investigate the microstructure of the ceramic pebbles from the Pebble Bed Assemblies. This paper concentrates on the Post Irradiation Examination (PIE) of the four ceramic pebble beds that have been irradiated in the Pebble Bed Assembly experiment for the HCPB blanket concept. Two assemblies with Li 4 SiO 4 pebble-beds are operated at different maximum temperatures of approximately 600 o C and 800 o C. Post irradiation computational analysis has shown that both have different creep deformation. Two other assemblies have been loaded with a ceramic breeder bed of two types of Li 2 TiO 3 beds having different sintering temperatures and consequently different creep behavior. The irradiation maximum temperature of the Li 2 TiO 3 was 800 o C. To support the first PIE result, the post irradiation thermal analysis will be discussed because thermal gradients have influence on the pebble-bed thermo-mechanical behavior and as a result it may have impact on the structural integrity of the ceramic breeder materials. (author)

  16. Advances in fluidized bed technologies

    International Nuclear Information System (INIS)

    Mutanen, K.

    1992-01-01

    Atmospheric fluidized bed combustion (AFBC) has advanced into industrial cogeneration and utility-scale electric generation. During the 1980's AFBC became the dominant technology in the United States for power generation systems fired with solid fuels. Development of pressurized fluidized bed combustion/gasification (PFB/G) has grown rapidly from small bench-scale rigs to large pilot and demonstration plants. AFBC as large as 160 MWe in capacity are now in operation, while pressurized combustion systems generating 80 MWe have started up two years ago. The major driving forces behind development of fluidized bed technologies are all the time strictening emission control regulations, need for fuel flexibility, repowering of older power plants and need for higher efficiency in electricity generation. Independent power producers (IPP) and cogenerators were the first ones in the United States who accepted AFBC for wide commercial use. Their role will be dominant in the markets of the 1990's also. Developers of AFBC systems are working on designs that reduce investment costs, decrease emissions and offer even higher reliability and availability in utility-scale applications while developers of PFBC/G work on designs that increase plant efficiencies, allow modular construction, decrease emissions further and reduce the cost of generating power. This paper presents technological background, commercial status, boiler performance, emissions and future developments for both AFBC and PFBC/G systems

  17. Natural gas in coal beds

    Energy Technology Data Exchange (ETDEWEB)

    Kravtsov, A.I.; Voytov, G.I.

    1983-01-01

    The special importance is noted of the problem of computing and careful use of the energy raw material, coal, oil and natural gases. An examination is made of the mechanism for the formation of carboniferous gases in the beds with the use of the model of coal macromolecule. A schematic section is presented for the coal field and plan for vertical gas zonality. The change in chemical composition of the natural gases with depth is governed by the countermovement of the natural gases: from top to bottom the gases of the earth's atmosphere move, mainly oxygenand nitrogen, from bottom to top, the gases of metamorphic and deep origin. Constant isotope composition of the carbon in the fossil coals is noted. The distribution of the quanitity deltaC/sup 13/ of carbon in the fossil coals of the Donets basin is illustrated. The gas content of the coal beds and gas reserves are discussed. The flowsheet is shown for the unit for degasification of the coal bed before the cleaning face.

  18. Estimated loads of suspended sediment and selected trace elements transported through the Clark Fork basin, Montana, in selected periods before and after the breach of Milltown Dam (water years 1985-2009)

    Science.gov (United States)

    Sando, Steven K.; Lambing, John H.

    2011-01-01

    Milltown Reservoir is a National Priorities List Superfund site in the upper Clark Fork basin of western Montana where sediments enriched in trace elements from historical mining and ore processing have been deposited since the completion of Milltown Dam in 1908. Milltown Dam was breached on March 28, 2008, as part of Superfund remediation activities to remove the dam and excavate contaminated sediment that had accumulated in Milltown Reservoir. In preparation for the breach of Milltown Dam, permanent drawdown of Milltown Reservoir began on June 1, 2006, and lowered the water-surface elevation by about 10 to 12 feet. After the breach of Milltown Dam, the water-surface elevation was lowered an additional 17 feet. Hydrologic data-collection activities were conducted by the U.S. Geological Survey in cooperation with U.S. Environmental Protection Agency to estimate loads of suspended sediment and trace elements transported through the Clark Fork basin before and after the breach of Milltown Dam. This report presents selected results of the data-collection activities.

  19. Using Natural Boundary Conditions to Probe the Internal Dynamics of Pyroclastic Flows: Mass, Enthalpy and Momentum Transfer at the Flow-Bed Interface

    Science.gov (United States)

    Dufek, J.; Bergantz, G. W.; Manga, M.

    2006-12-01

    The interaction of pyroclastic density currents with their substrate plays a significant role in the transport and deposition of these flows. The basal particle concentration of these flows will ultimately determine the mechanism of mass, enthalpy and momentum transfer and the sensitivity of these flows to bed roughness, topography and even their ability to cross bodies of water. In order to probe the internal structure of these flows we used an Eulerian-Eulerian-Lagrangian (EEL) computational approach coupled with an examination of ignimbrite deposits of the Kos Plateau Tuff (KPT) and the near-shore deposits of the 2003 Montserrat dome collapse (Allen and Cas, 2001; Edmonds and Herd, 2005). In particular, the KPT eruption provides a unique opportunity to compare flows that have traversed a body of water (and thereby filtering out their bed-load) versus flows that have traveled over-land. The examined Montserrat pyroclastic flows also encounter the ocean, and comparison with observations of the recently produced near-shore deposits allow us to access the near-surface energy transfer required to produce the observed steam explosions and the mass transfer necessary to produce tsunami. This coupled deposit-driven and numerical investigation reveals that energy-dissipation at the basal boundary is one of the primary factors determining the run-out distance of pyroclastic flows. A significant portion of the momentum of over-land flows is transported in a bed-load region dominated by numerous particle-particle and particle-boundary interactions. Mass and energy transfer in the near shore environment produce tsunami and steam explosions, which result in preferential fining in the proximal deposits and a source of water vapor to the propagating currents. However, the simulations indicate the internal structure and head of the pyroclastic density current are not significantly impacted by the steam explosions after they have traveled several kilometers away from the shore as

  20. The characteristics of bed agglomeration during fluidized bed combustion of eucalyptus bark

    International Nuclear Information System (INIS)

    Chaivatamaset, Pawin; Tia, Suvit

    2015-01-01

    The bed agglomeration behaviors were investigated experimentally when eucalyptus bark was burning tested in a laboratory scale fluidized bed reactor. The focuses of this work were the influences of operating conditions and bed materials on the bed agglomeration tendency and the elucidation in the behaviors of fuel inorganic elements and the governing mode of the agglomeration. It was found that the defluidization caused by the bed agglomeration was clearly detectable from the decrease in measured bed pressure. The growth of bed particle and accumulation of agglomerates during combustion provided the partial to complete defluidization. The defluidization was promoted by the increase of bed temperature and bed particle size, and the decrease of fluidizing air velocity. The SEM-EDS analyses revealed that the bed agglomeration was mainly attributed to the formation of potassium silicate compounds as liquid phase during the combustion. This was initiated by the chemical reaction between the bed particle and the released ash constituents. In this study, the inorganic migration from fuel particle to bed particle was likely dominated by the condensation/reaction. The thermodynamic examination by ternary phase diagram analysis corroborated that the liquid phase formation of the ash derived materials controlled the agglomeration. The alumina sand prevented the bed agglomeration since it was inactive in the formation of viscous molten substances during combustion at the observed temperatures. - Highlights: • The behaviors of bed agglomeration were studied during the fluidized bed combustion of eucalyptus bark. • The increase in bed temperature and sand size, and the decrease of air velocity promoted bed defluidization. • The formation of molten potassium silicate compounds conduced to the bed agglomeration. • Condensation/reaction was the dominant inorganic migration mechanism from fuel particle to bed particle. • The alumina sand prevented effectively the bed

  1. Bed agglomeration characteristics of palm shell and corncob combustion in fluidized bed

    International Nuclear Information System (INIS)

    Chaivatamaset, Pawin; Sricharoon, Panchan; Tia, Suvit

    2011-01-01

    Bed particle agglomeration was studied experimentally in an atmospheric laboratory scale fluidized bed combustor using quartz sand as bed material. Palm shell and corncob were tested. The objectives of the study were (i) to describe the contributions of the biomass ash properties and the operating conditions on the bed agglomeration tendency in term of the bed defluidization time (t def ) and the extent of potassium accumulation in the bed (K/Bed) and (ii) to further elucidate the ash inorganic behaviors and the governing bed agglomeration mechanisms. Defluidization caused by the bed agglomeration was experienced in all experiments during combustion of these biomasses, as a consequence of the presence of potassium in biomass. The experimental results indicated that biomass ash characteristics were the significant influence on the bed agglomeration. The increasing bed temperature, bed particle size and static bed height and the decreasing fluidizing air velocity enhanced the bed agglomeration tendency. The SEM/EDS analyses on the agglomerates confirmed that the agglomeration was attributed to the formation of potassium silicate liquid enriched on the surface of quartz sand particles in conjunction with the high surface temperature of the burning biomass char particles. Thermodynamic examination based on the phase diagram analysis confirmed that the molten phase formation was responsible for the agglomeration. In this study, the high molten ash fraction resulting from the high potassium content in biomass promoted the agglomeration and thus defluidization. - Highlights: → Palm shell and corncob of Thailand are tested their bed agglomeration behaviors during fluidized bed combustion. → The increase of bed temperature, bed particle size and static bed height and the decrease of air velocity enhance bed agglomeration. → The formation of ash derived potassium silicate melts enriched on sand surface is the key process. → The collision between char and sand

  2. Magnetic resonance imaging assessment of trunk muscles during prolonged bed rest.

    Science.gov (United States)

    Hides, Julie A; Belavý, Daniel L; Stanton, Warren; Wilson, Stephen J; Rittweger, Jörn; Felsenberg, Dieter; Richardson, Carolyn A

    2007-07-01

    Prospective longitudinal study. OBJECTIVE.: To investigate, using magnetic resonance imaging (MRI), the influence of bed rest on the lumbopelvic musculature. Reduced gravitational loading and inactivity (bed rest) are known to result in significant change in musculoskeletal function, although little is known about its effects on specific muscles of the lumbopelvic region. Ten healthy male subjects underwent 8 weeks of bed rest with 6 months of follow-up. MRI of the lumbopelvic region was conducted at regular time-points during and after bed rest. Using uniplanar images at L4, cross-sectional areas (CSAs) of the multifidus, lumbar erector spinae, quadratus lumborum, psoas, anterolateral abdominal, and rectus abdominis muscles were measured. Multifidus CSA decreased by day 14 of bed rest (F = 7.4, P = 0.04). The lumbar erector spinae and quadratus lumborum CSA showed no statistically significant difference to baseline across the time of bed rest (P > 0.05). The anterolateral abdominal, rectus abdominis, and psoas CSA all increased over this time. Psoas CSA increased by day 14 (F = 6.9, P = 0.047) and remained so until day 56, whereas the anterolateral abdominal CSA (F = 29.4, P = 0.003) and rectus abdominis CSA (F = 8.9, P = 0.03) were not statistically larger than baseline until day 56. On reambulation after completion of the bed rest phase, multifidus, anterolateral abdominal, and rectus abdominis CSA returned to baseline levels (P > 0.05) by day 4 of follow-up, whereas psoas CSA returned to baseline level after day 28 of the follow-up period. Bed rest resulted in selective atrophy of the multifidus muscle. An increased CSA of the trunk flexor musculature (increases in psoas, anterolateral abdominal, and rectus abdominis muscles) may reflect muscle shortening or possible overactivity during bed rest. Some of the changes resemble those seen in low back pain and may in part explain the negative effects of bed rest seen in low back pain sufferers.

  3. Clinical evaluation of an automated turning bed.

    Science.gov (United States)

    Melland, H I; Langemo, D; Hanson, D; Olson, B; Hunter, S

    1999-01-01

    The purposes of this study were to assess client comfort and sleep quality, client physiologic response (skin and respiratory status), the effect on the need for caregiver assistance, and cost when using an automated turning bed. Nonexperimental, evaluative study. Twenty-four adult home or long-term care resident subjects who had a degenerative disease, spinal cord injury, stroke, cerebral palsy, or back surgery. Each subject agreed to use the automated turning bed for four weeks. Researchers completed a demographic survey and skin assessment, and assessed each subject for pressure ulcer risk and for the need of assistance of a care giver for turning before and after the four weeks of using the turning bed. Subjects rated the turning bed in terms of comfort and sleep quality. Subjects rated the turning bed as more comfortable than their own bed and expressed satisfaction at the pain relief attained when on the turning bed. While using the turning bed, there was a significant improvement in sleep quality. No skin breakdown or deterioration in respiratory status occurred. Fewer subjects required the assistance of a caregiver for turning when on the turning bed. This automated turning bed shows great promise in meeting a need for patients with limited mobility whether they are homebound or in a residential community. Future studies that further investigate use of the turning bed for postoperative back patients while still in the acute care setting are indicated. Replicative studies with a larger sample size are also indicated.

  4. Fault controlled dissolution of bedded rock salt

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, Neil L.; Knapp, Ralph W. [Kansas Geological Survey, Lawrence, KS (United States); Brown, R. James [Calgary Univ., AB (Canada)

    1993-12-31

    Analysis of well log and seismic data suggest that about 40 m of Famennian-age bedded rock salt was uniformly deposited within the Wabamun Group in the Stettler area, southeastern Alberta, Canada. Subsequent to deposition, this original rock salt was leached to the extent that is preserved, now only as isolated-to-contiguous bodies of irregular shape and variable thickness. In the immediate study area, dissolution appears to have been initiated by regional faulting and/or fracturing during the mid-Late Cretaceous, and accentuated thereafter by various large-scale mechanisms including glaciation. In this paper, seismic data across a prominent NNE trending salt-dissolution feature in the Stettler area are presented. In short cross-section, this subsidence feature is manifested as an up-ward-expanding zone of measurable subsidence, characterized by increased structural relief at greater depths, and small-amplitude near-vertical offsets. This subsidence feature is consistent with: the onset of salt dissolution as a result of regional faulting and/or fracturing during mid-Late Cretaceous time; the plastic deformation of rock salt creep; the gradual (as opposed to catastrophic) subsidence of the post-salt strata; and accelerated rates of leaching during the Pleistocene and Holocene in response to glacial loading and unloading. (author). 12 refs., 4 figs

  5. COMPUTATIONAL MODELING OF CIRCULATING FLUIDIZED BED REACTORS

    Energy Technology Data Exchange (ETDEWEB)

    Ibrahim, Essam A

    2013-01-09

    Details of numerical simulations of two-phase gas-solid turbulent flow in the riser section of Circulating Fluidized Bed Reactor (CFBR) using Computational Fluid Dynamics (CFD) technique are reported. Two CFBR riser configurations are considered and modeled. Each of these two riser models consist of inlet, exit, connecting elbows and a main pipe. Both riser configurations are cylindrical and have the same diameter but differ in their inlet lengths and main pipe height to enable investigation of riser geometrical scaling effects. In addition, two types of solid particles are exploited in the solid phase of the two-phase gas-solid riser flow simulations to study the influence of solid loading ratio on flow patterns. The gaseous phase in the two-phase flow is represented by standard atmospheric air. The CFD-based FLUENT software is employed to obtain steady state and transient solutions for flow modulations in the riser. The physical dimensions, types and numbers of computation meshes, and solution methodology utilized in the present work are stated. Flow parameters, such as static and dynamic pressure, species velocity, and volume fractions are monitored and analyzed. The differences in the computational results between the two models, under steady and transient conditions, are compared, contrasted, and discussed.

  6. Critical Issues for Particle-Bed Reactor Fuels

    Science.gov (United States)

    Evans, Robert S.; Husser, Dewayne L.; Jensen, Russell R.; Kerr, John M.

    1994-07-01

    Particle-Bed Reactors (PBRs) potentially offer performance advantages for nuclear thermal propulsion, including very high power densities, thrust-to-weight ratios, and specific impulses. A key factor in achieving all of these is the development of a very-high-temperature fuel. The critical issues for all such PBR fuels are uranium loading, thermomechanical and thermochemical stability, compatibility with contacting materials, fission product retention, manufacturability, and operational tolerance for particle failures. Each issue is discussed with respect to its importance to PBR operation, its status among current fuels, and additional development needs. Mixed-carbide-based fuels are recommended for further development to support high-performance PBRs.

  7. A parametric study pf powder holdups in a packed bed under ...

    African Journals Online (AJOL)

    More specifically, a parametric study is performed to determine the effects of the gas blast velocity, particle size adn powder loading on the powder holdups. Results are presented in terms of fines accumulation area. This work shows the dependency of the powder holdups on the packed bed flow parameters. Keywords: ...

  8. Operation of Packed-Bed Reactors Studied in Microgravity

    Science.gov (United States)

    Motil, Brian J.; Balakotaiah, Vemuri

    2004-01-01

    The operation of a packed bed reactor (PBR) involves gas and liquid flowing simultaneously through a fixed-bed of solid particles. Depending on the application, the particles can be various shapes and sizes but are generally designed to force the two fluid phases through a tortuous route of narrow channels connecting the interstitial space. The PBR is the most common type of reactor in industry because it provides for intimate contact and high rates of transport between the phases needed to sustain chemical or biological reactions. The packing may also serve as either a catalyst or as a support for growing biological material. Furthermore, this type of reactor is relatively compact and requires minimal power to operate. This makes it an excellent candidate for unit operations in support of long-duration human space activities.

  9. The Safety of Hospital Beds: Ingress, Egress, and In-Bed Mobility.

    Science.gov (United States)

    Morse, Janice M; Gervais, Pierre; Pooler, Charlotte; Merryweather, Andrew; Doig, Alexa K; Bloswick, Donald

    2015-01-01

    To explore the safety of the standard and the low hospital bed, we report on a microanalysis of 15 patients' ability to ingress, move about the bed, and egress. The 15 participants were purposefully selected with various disabilities. Bed conditions were randomized with side rails up or down and one low bed with side rails down. We explored the patients' use of the side rails, bed height, ability to lift their legs onto the mattress, and ability to turn, egress, and walk back to the chair. The standard bed was too high for some participants, both for ingress and egress. Side rails were used by most participants when entering, turning in bed, and exiting. We recommend that side rails be reconsidered as a means to facilitate in-bed movement, ingress, and egress. Furthermore, single deck height settings for all patients are not optimal. Low beds as a safety measure must be re-evaluated.

  10. Unethical evidence against cattle dignity during loading ...

    African Journals Online (AJOL)

    Some activities that showed unethical practices against cattle during loading, transportation and off-loading were considered in this paper. Three major cattle market centres (Akinyele, Bodija and Oranyan) in Ibadan metropolis were used. Eighty (80) structured questionnaires were randomly administered to the cattle ...

  11. Baseline axle load survey in Malawi - 2014

    CSIR Research Space (South Africa)

    Roux, M

    2015-07-01

    Full Text Available As part of the project to update the Malawian Directorate of Road Transport and Safety Services’ (DRTSS) 2005 Axle Load Control Strategy and to provide a five-year implementation plan, a country-wide axle load survey was undertaken to assess...

  12. Laboratory studies on bedload transport under unsteady flow conditions

    OpenAIRE

    Mrokowska Magdalena M.; Rowiński Paweł M.; Książek Leszek; Strużyński Andrzej; Wyrębek Maciej; Radecki-Pawlik Artur

    2018-01-01

    Two sets of triangular hydrographs were generated in a 12-m-long laboratory flume for two sets of initial bed conditions: intact and water-worked gravel bed. Flowrate ranging from 0.0013 m3 s-1 to 0.0456 m3 s-1, water level ranging from 0.02 m to 0.11 m, and cumulative mass of transported sediment ranging from 4.5 kg to 14.2 kg were measured. Then, bedload transport rate, water surface slope, bed shear stress, and stream power were evaluated. The results indicated the impact of initial bed co...

  13. Particle bed reactor scaling relationships

    Science.gov (United States)

    Slovik, G.; Araj, K.; Horn, F. L.; Ludewig, H.; Benenati, R.

    The Particle Bed Reactor (PBR) concept can be used in several applications both as part of a power generating system or as a direct propulsion unit. In order to carry out optimization studies of systems involving a PBR, it is necessary to know the variation of the critical mass with pertinent system parameters such as weight, size, power level and thrust level. A parametric study is presented for all the practical combinations of fuel and moderating material. The PBR is described, the practical combinations of materials and dimensions are discussed, and an example is presented.

  14. Suspension of bed material over sand bars in the Lower Mississippi River and its implications for Mississippi delta environmental restoration

    Science.gov (United States)

    Ramirez, Michael T.; Allison, Mead A.

    2013-06-01

    specific pathways for sand transport in the lower reaches of large rivers, including the Mississippi, is a key for addressing multiple significant geologic problems, such as delta building and discharge to the oceans, and for environmental restoration efforts in deltaic environments threatened by rising sea levels. Field studies were performed in the Mississippi River 75-100 km upstream of the Gulf of Mexico outlet in 2010-2011 to examine sand transport phenomena in the tidally affected river channel over a range of discharges. Methods included mapping bottom morphology (multibeam sonar), cross-sectional and longitudinal measurements of water column velocity and acoustic backscatter, suspended sediment sampling, and channel-bed sampling. Substantial interaction was observed between the flow conditions in the river (boundary shear stress), channel-bed morphology (size and extent of sandy bedforms), and bed material sand transport (quantity, transport mode, and spatial distribution). A lateral shift was observed in the region of maximum bed material transport from deep to shallow areas of subaqueous sand bars with increasing water discharge. Bed material was transported both in traction and in suspension at these water discharges, and we posit that the downriver flux of sand grains is composed of both locally- and drainage basin-sourced material, with distinct transport pathways and relations to flow conditions. We provide suggestions for the optimal design and operation of planned river diversion projects.

  15. Sand Bed Morphodynamics under Standing Waves and Vegetated Conditions

    Science.gov (United States)

    Landry, B. J.; Garcia, M. H.

    2010-12-01

    Littoral processes such as sediment transport, wave attenuation, and boundary layer development are governed by the presence of bathymetric features, which include large-scale sand bars upon which smaller-scale sand ripples are superimposed, as well as the presence of submarine vegetation. Numerous studies on sand ripples and bars have aided to elucidate the dynamics in oscillatory flows; however, the effect of vegetation on the system is less understood. Recent laboratory studies have focused on quantifying wave attenuation by emergent vegetation as a natural method to mitigate storm surges. The emergent vegetation, while promising for coastal protection, alters sediment transport rates directly by the physical presence of the plants near the bed and indirectly from reduction in near-bed shear stresses due to attenuated wave energy. The experimental work herein focuses on the area near the deeply submerged vegetated canopy limit (current work has a ratio of mean still water depth to plant height, H/h, = 7.9) to minimize the effect on the surface waves and discern the direct impact vegetation has on sand bed morphodynamics. Experiments were conducted in the large wave tank (49-m long by 1.83-m wide by 1.22-m deep) in the Ven Te Chow Hydrosystems Laboratory at the University of Illinois in which a high reflection wave forcing was used over a uniform sand bed with a 0.25-mm median sediment diameter in which staggered and uniform arrangements of idealized vegetation (i.e., 6.35-mm diameter rigid wooden cylinders) were positioned along the bed (e.g., at predetermined sand bar troughs and over an entire sand bar). The resulting bathymetric evolution from the vegetated case experiments were compared to the base case of no vegetation using two optical methods: a high-resolution laser displacement sensor for three-dimensional surveys and digitized profiles via high-definition panoramic images of the entire test section. The experimental findings illustrate the profound

  16. Measurements and theoretical modeling of effective thermal conductivity of particle beds under compression in air and vacuum

    Directory of Open Access Journals (Sweden)

    Jingwen Mo

    2017-09-01

    Full Text Available Effective thermal conductivity experiments were carried out with spherical particle beds under low and high compressive pressure loading in vacuum and air. A theoretical model was proposed for the effective thermal conductivity of particle beds based on the experimental results. The model incorporates heat conduction by particles including contact thermal resistance between particles, conduction through the gas in between particles, and radiation between particles, and includes two fitting parameters, namely the coefficient of heat conducted through the fluid, and the macro-contact thermal resistance. The predictions from the theoretical model satisfactorily match the experimental data for the bed effective thermal conductivity over the range of applied loading pressures on particles with different Young's modulus and the gas environment. The model can be used generally to describe the effect of compression stress or pressure on effective thermal conductivity of particle beds.

  17. Fluvial sediment transport in a glacier-fed high-mountain river (Riffler Bach, Austrian Alps)

    Science.gov (United States)

    Morche, David; Weber, Martin; Faust, Matthias; Schuchardt, Anne; Baewert, Henning

    2017-04-01

    High-alpine environments are strongly affected by glacier retreat since the Little Ice Age (LIA). Due to ongoing climate change the hydrology of proglacial rivers is also influenced. It is expected that the growing proportions of snow melt and rainfall events will change runoff characteristics of proglacial rivers. Additionally, the importance of paraglacial sediment sources in recently deglaciating glacier forefields is increasing, while the role of glacial erosion is declining. Thus complex environmental conditions leading to a complex pattern of fluvial sediment transport in partly glaciated catchments of the European Alps. Under the umbrella of the joint PROSA-project the fluvial sediment transport of the river Riffler Bach (Kaunertal, Tyrol, Austria) was studied in 3 consecutive ablation seasons in order to quantify sediment yields. In June 2012 a probe for water level and an automatic water sampler (AWS) were installed at the outlet of the catchment (20km2). In order to calculate annual stage-discharge-relations by the rating-curve approach, discharge (Q) was repeatedly measured with current meters and by salt dilution. Concurrent to the discharge measurements bed load was collected using a portable Helley-Smith sampler. Bed load samples were weighted and sieved in the laboratory to gain annual bed load rating curves and grain size distributions. In total 564 (2012: 154, 2013: 209, 2014: 201) water samples were collected and subsequently filtered to quantify suspended sediment concentrations (SSC). Q-SSC-relations were calculated for single flood events due to the high variability of suspended sediment transport. The results show a high inter- and intra-annual variability of solid fluvial sediment transport, which can be explained by the characteristics of suspended sediment transport. Only 13 of 22 event-based Q-SSC-relations show causal dependency. In 2012, during a period with multiple pluvial-induced peak discharges most sediment was transported. On the

  18. 49 CFR 1247.1 - Annual Report of Cars Loaded and Cars Terminated.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 9 2010-10-01 2010-10-01 false Annual Report of Cars Loaded and Cars Terminated... TRANSPORTATION BOARD, DEPARTMENT OF TRANSPORTATION (CONTINUED) ACCOUNTS, RECORDS AND REPORTS REPORT OF CARS LOADED AND CARS TERMINATED § 1247.1 Annual Report of Cars Loaded and Cars Terminated. Beginning with the...

  19. DEGRADATION OF AROMATIC COMPOUNDS USING MOVING BED BIOFILM REACTORS

    Directory of Open Access Journals (Sweden)

    B. Ayati, H. Ganjidoust, M. Mir Fattah

    2007-04-01

    Full Text Available For biological treatment of water, there are many different biofilm systems in use. Examples of them are trickling filters, rotating biological contactors, fixed media submerged biofilters, granular media biofilters and fluidized bed reactors. They all have their advantages and disadvantages. Hence, the Moving Bed Biofilm Reactor process was developed in Norway in the late 1980s and early 1990s to adopt the best features of the activated sludge process as well as those of the biofilter processes, without including the worst. Two cylindrical moving bed biofilm reactors were used in this study working in upflow stream conditions. Experiments have been done in aerobic batch flow regime. Laboratory experiments were conducted at room temperature (23–28C and synthetic wastewater comprising a composition of phenol and hydroquinone in each reactor as the main organic constituents, plus balanced nutrients and alkalinity were used to feed the reactor. The ratio of influent to effluent COD was determined at different retention times. The results indicated that the removal efficiency of each selected compound is affected by the detention time. At low phenol and hydroquinone concentration (from 700 to 1000 mg/L maximum removal efficiency (over 80 % was obtained. By further increasing in COD loading rate up to 3000 mg/L, a decrease in COD removal rate was occurred. In the reactor containing pyrogallol in COD of 1500 mg/L, the removal rate decreased to 10 percent because of its toxicity for microorganisms.

  20. The influence of bed roughness on partial alluviation in an experimental bedrock channel

    Science.gov (United States)

    Davis, J. R.; Sklar, L. S.; Demeter, G. I.; Johnson, J. P.; Whipple, K. X.

    2005-12-01

    The extent of alluvial cover on a bedrock channel bed strongly influences the efficiency of river incision, and can affect the quality of habitat for aquatic ecosystems. The extent of partial cover is commonly modeled as a simple function of sediment supply relative to the transport capacity of the stream, although other factors are likely to be important, particularly the roughness of the underlying bedrock surface. Here we report results of a set of laboratory experiments investigating the influence of bedrock channel bed topography on the dynamics of partial bed alluviation. The experiments were conducted in a tilting flume 8 m long and 0.3 m wide with an erodible bedrock bed made of a sand-cement mixture. The flume has a calibrated sediment feed and a double-basket sediment trap that provides a continuous record of sediment flux out of the downstream end. We used a uniform grain size of 5 mm, and varied the sediment supply rate from zero to that sufficient to create a fully alluviated bed. We created a variety of bedrock roughness conditions, from smooth, nearly planar surfaces to an egg-carton texture made with a plaster-coated foam mold. Intermediate roughness was achieved by chiseling into smooth beds and by allowing the bed topography to evolve by sustained bedload abrasion. We used a laser microtopography scanning device to make topographic maps of the bed surface, with a vertical resolution of 0.2 mm and a horizontal spacing of 5 mm. From these data we quantify bedrock bed roughness as the standard deviation of the distribution of bed elevations relative to a plane inclined at the mean bed slope. To guide our selection of bed roughness values we made topographic surveys of a number of bedrock channel beds, including partially alluviated channels where we dug trenches through alluvial deposits to expose the underlying bedrock surface. For each bed roughness condition we systematically varied the sediment supply rate and repeatedly mapped the extent of

  1. Process development and modeling of fluidized-bed reactor with coimmobilized biocatalyst for fuel ethanol production

    Science.gov (United States)

    Sun, May Yongmei

    was 25--44g/L-hr (based on reactor volume), the average yield was 0.45 g ethanol/g starch, the biocatalyst retained physical integrity and contamination did not affect fermentation. For the Z. mobilis system the maximum volumetric productivity was 38 g ethanol/L-h, the average yield was 0.51 g ethanol/g starch and the FBR was successfully operated for almost one month. In order to develop, scale-up and economically evaluate this system more efficiently, a predictive mathematical model that is based on fundamental principles was developed and verified. This model includes kinetics of reactions, transport phenomena of the reactant and product by diffusion within the biocatalyst bead, and the hydrodynamics of the three phase fluidized bed. The co-immobilized biocatalyst involves a consecutive reaction mechanism The mathematical descriptions of the effectiveness factors of reactant and the intermediate product were developed. Hydrodynamic literature correlations were used to develop the dispersion coefficient and gas, liquid, and solid holdup. The solutions of coupled non-linear second order equations for biocatalyst bead and reactor together with the boundary conditions were solved numerically. This model gives considerable information about the system, such as concentration profiles inside both the beads and column, flow rate and feed concentration influences on productivity and phase hold up, and the influence of enzyme and cell mass loading in the catalyst. This model is generic in nature such that it can be easily applied to a diverse set of applications and operating conditions.

  2. On partial fluidization in rotating fluidized beds

    International Nuclear Information System (INIS)

    Kao, J.; Pfeffer, R.; Tardos, G.I.

    1987-01-01

    In a rotating fluidized bed, unlike in a conventional fluidized bed, the granules are fluidized layer by layer from the (inner) free surface outward at increasing radius as the gas velocity is increased. This is a very significant and interesting phenomenon and is extremely important in the design of these fluidized beds. The phenomenon was first suggested in a theoretical analysis and recently verified experimentally in the authors' laboratory. However, in the first paper, the equations presented are too cumbersome and the influence of bed thickness is not clearly stated. In this note the authors present simplified equations, based on that paper, for the pressure drop and the minimum fluidizing velocities in a rotating fluidized bed. Experimental data are also shown and compared with the theoretical model, and the effect of bed thickness is shown. Furthermore, an explanation for the observation of a maximum in the pressure drop vs. velocity curve instead of the plateau derived by Chen is proposed

  3. Gruppebaseret behandling af BED - et faseopdelt behandlingstilbud

    DEFF Research Database (Denmark)

    Laust, Jakob; Lau, Marianne Engelbrecht; Waaddegaard, Mette

    2015-01-01

    Titel: Afrapportering vedr. SATS-puljemidler til behandling og erfaringsopsamling vedr. BED for perioden 1. marts 2013 – 1. maj 2015. Baggrund: Binge Eating Disorder (BED), på dansk tvangsoverspisning, er en udbredt, men overset spiseforstyrrelse med alvorlige psykiske, fysiske og sociale...... konsekvenser. BED blev i 2013 optaget i DSM-5 (Diagnostic and Statistical Manual of Mental Disorders) som en selvstændig diagnose og BED forventes medtaget i den forestående revision af det internationale diagnose system, ICD-11. Sundhedsstyrelsen gav på denne baggrund satspuljemidler til erfaringsopsamling...... vedr. BED. I den forbindelse ansøgte Ambulatorium for Spiseforstyrrelser på Psykoterapeutisk Center Stolpegård ovenstående midler til at udvikle en ambulant, primært psykoterapeutisk gruppebehandling til patienter med moderat til svær BED med fokus på såvel spiseforstyrrelse såvel som overvægt. Metode...

  4. Theoretical and Experimental Substantiation for Applicability of a Damping Layer in a Foundation Slab Placed on Soil Bed

    Directory of Open Access Journals (Sweden)

    Kiselev Nikita

    2016-01-01

    Full Text Available Authors present the results of studies of innovative foundation structure. The idea of how to increase the operational quality of foundations and reduce the costs due to rational loading of the soil bed is numerically simulated. It is shown that the bending moment in the foundation slab depends on uneven settlements of the soil bed. It is proposed to stabilize the deformable soil bed by the damping layer placed under the slab footing in the zones with minor settlements. Considered is the concept of the damping layer in the foundation slab placed on the soil bed (DLS. The in-situ test for DLS-clayey bed interaction is described. Given are the results obtained after the experiments for DLS performance. The result of DLS implementation in designing the foundation of the 22-storeyed block of flats is considered. The expediency of DLS in comparison to standard foundations is presented.

  5. Gas distributor for fluidized bed coal gasifier

    Science.gov (United States)

    Worley, Arthur C.; Zboray, James A.

    1980-01-01

    A gas distributor for distributing high temperature reaction gases to a fluidized bed of coal particles in a coal gasification process. The distributor includes a pipe with a refractory reinforced lining and a plurality of openings in the lining through which gas is fed into the bed. These feed openings have an expanding tapered shape in the downstream or exhaust direction which aids in reducing the velocity of the gas jets as they enter the bed.

  6. Measurements, patterns, and controls of nitrogen flux in a cranberry bed during the harvest flood

    Science.gov (United States)

    Kennedy, C. D.

    2012-12-01

    Nitrogen (N) is an essential nutrient for cranberry production but also a source of freshwater eutrophication in southeastern Massachusetts. Surface application of N fertilizer is pervasive throughout the cranberry industry, accounting for 93% of total annual N export from farms. The agricultural practice of "wet harvesting", involving the flooding of farms with ~1 ft of water, may promote the vertical transport and transformation of nitrogen in cranberry beds. A cranberry bed at the University of Massachusetts Cranberry Station (East Wareham, MA) has been instrumented with a network of hydrological monitoring equipment for quantifying patterns and controls of nitrogen dynamics during the harvest flood. Here, data of (1) hydraulic head gradient between floodwater and groundwater (J), (2) hydraulic conductivity (K), and (3) N concentration in groundwater (C) collected from multiple points on the cranberry bed will be presented, and used to evaluate the patterns and controls N fluxes (f = JKC) in the cranberry bed.

  7. Gas filtration in binary fluidized beds

    Energy Technology Data Exchange (ETDEWEB)

    Rincon, J. (Univ. de Castilla-La Mancha, Ciudad Real (Spain)); Guardiola, J.; Romero, A. (Univ. de Alcala de Henares, Madrid (Spain))

    1992-12-01

    A systematic experimental study of aerosol filtration in a binary fluidized bed of dielectric material is carried out. Measurements of the collection efficiency when such parameters as gas velocity, bed height, collecting mixture, and column diameter are varied over a wide range have been made. Experimental evidence is given to show that charges generated naturally by triboelectrification of the bed dielectric particles can considerably increase the efficiency of such beds. Furthermore, it is demonstrated that a proper choice of the fluidized mixture can significantly improve the performance of such filters.

  8. Air purification from a mixture VOCs in the pilot-scale trickle-bed bioreactor (TBB)

    Science.gov (United States)

    Sarzyński, Rafał; Gąszczak, Agnieszka; Janecki, Daniel; Bartelmus, Grażyna

    2017-10-01

    The efficiency of the air bio-purification from the mixture of two volatile organic compounds (styrene and p-xylene) was studied. The process was carried out in a pilot-scale trickle-bed bioreactor installation designed to purify ˜200 m3h-1 of the polluted air. The bioreactor operated at concurrent flow of gas and liquid (mineral salt solution) through packing (polypropylene Ralu rings) covered with a thin layer of microorganisms (bacterial consortium of Pseudomonas sp. E-022150 and Pseudomonas putida mt-2). The experiments, carried out for various values of a reactor load with pollutant, confirmed the great efficiency of the investigated process. At the tested bed load with pollution (inlet specific pollutant load was changed within the range of 41 - 84 gm-3 h -1), styrene conversion degree changed within the range of 80-87% and p-xylene conversion degree within the range of 42-48%.

  9. Thermoelastic analyses of spent fuel repositories in bedded and dome salt. Technical memorandum report RSI-0054

    International Nuclear Information System (INIS)

    Callahan, G.D.; Ratigan, J.L.

    1978-01-01

    Global thermoelastic analyses of bedded and dome salt models showed a slight preference for the bedded salt model through the range of thermal loading conditions. Spent fuel thermal loadings should be less than 75 kW/acre of the repository pending more accurate material modeling. One should first limit the study to one or two spent fuel thermal loading (i.e. 75 kW/acre and/or 50 kW/acre) analyses up to a maximum time of approximately 2000 years. Parametric thermoelastic type analyses could then be readily obtained to determine the influence of the thermomechanical properties. Recommendations for further study include parametric analyses, plasticity analyses, consideration of the material interfaces as joints, and possibly consideration of a global joint pattern (i.e. jointed at the same orientation everywhere) for the non-salt materials. Subsequently, the viscoelastic analyses could be performed

  10. Air purification from a mixture VOCs in the pilot-scale trickle-bed bioreactor (TBB

    Directory of Open Access Journals (Sweden)

    Sarzyński Rafał

    2017-01-01

    Full Text Available The efficiency of the air bio-purification from the mixture of two volatile organic compounds (styrene and p-xylene was studied. The process was carried out in a pilot-scale trickle-bed bioreactor installation designed to purify ∼200 m3h-1 of the polluted air. The bioreactor operated at concurrent flow of gas and liquid (mineral salt solution through packing (polypropylene Ralu rings covered with a thin layer of microorganisms (bacterial consortium of Pseudomonas sp. E-022150 and Pseudomonas putida mt-2. The experiments, carried out for various values of a reactor load with pollutant, confirmed the great efficiency of the investigated process. At the tested bed load with pollution (inlet specific pollutant load was changed within the range of 41 – 84 gm-3 h -1, styrene conversion degree changed within the range of 80-87% and p-xylene conversion degree within the range of 42-48%.

  11. Sediment transport under breaking waves

    DEFF Research Database (Denmark)

    Christensen, Erik Damgaard; Hjelmager Jensen, Jacob; Mayer, Stefan

    2000-01-01

    generated at the surface where the wave breaks as well as the turbulence generated near the bed due to the wave-motion and the undertow. In general, the levels of turbulent kinetic energy are found to be higher than experiments show. This results in an over prediction of the sediment transport. Nevertheless...

  12. Transport phenomena in particulate systems

    CERN Document Server

    Freire, José Teixeira; Ferreira, Maria do Carmo

    2012-01-01

    This volume spans 10 chapters covering different aspects of transport phenomena including fixed and fluidized systems, spouted beds, electrochemical and wastewater treatment reactors. This e-book will be valuable for students, engineers and researchers aiming to keep updated on the latest developments on particulate systems.

  13. Modeling hydraulic transport and anaerobic uptake by PAOs and GAOs during wastewater feeding in EBPR granular sludge reactors.

    Science.gov (United States)

    Weissbrodt, David G; Holliger, Christof; Morgenroth, Eberhard

    2017-08-01

    New-generation bioprocesses using granular sludge aim for a high-rate removal of nutrients from wastewater with low footprint. Achieving enhanced biological phosphorus removal (EBPR) relies on the design of sludge beds and wastewater feeding conditions to optimally load the biomass and to select for polyphosphate- (PAOs) over glycogen-accumulating organisms (GAOs) and over other heterotrophs. A hydraulic-metabolic mathematical model was developed to elucidate the impact of hydraulic transport patterns and environmental conditions on the PAO/GAO competition during up-flow feeding through an EBPR granular sludge bed. Tracer experiments highlighted plug-flow regimes with dispersion under both rapid (9 m h -1 , Re bed  = 1.6, Pe z  = 7.2, Pe t  = 4.6) and slow (0.9 m h -1 , Re bed  = 0.2, Pe z  = 21.3, Pe t  = 3.4) feeding. Non-turbulent regimes (Re bed  impacted bacterial competition for carbon uptake under anaerobic slow feeding. Feeding duration should be designed to avoid full depletion of intracellular storage polymers within static granules. PAOs bear twice longer feeding than GAOs by using both polyphosphate and glycogen hydrolysis to sustain anaerobic C-uptake. Alkaline conditions (pH 7.25-8.0) by, e.g., dosing lime in the feed select for PAOs independently of temperature (10-30°C). A twice higher bed is required for full anaerobic conversions at 10 rather than 20°C. Biosystem responses for anaerobic C-uptake can be anticipated using the model toward designing robust anaerobic selectors to manage the microbial resource in EBPR granular sludge. Biotechnol. Bioeng. 2017;114: 1688-1702. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  14. Initial prediction of dust production in pebble bed reactors

    Directory of Open Access Journals (Sweden)

    M. Rostamian

    2011-09-01

    Full Text Available This paper describes the computational simulation of contact zones between pebbles in a pebble bed reactor. In this type of reactor, the potential for graphite dust generation from frictional contact of graphite pebbles and the subsequent transport of dust and fission products can cause significant safety issues at very high temperatures around 900 °C in HTRs. The present simulation is an initial attempt to quantify the amount of nuclear grade graphite dust produced within a very high temperature reactor.

  15. Single particle behaviour in circulating fluidized bed combustors

    DEFF Research Database (Denmark)

    Erik Weinell, Claus

    1994-01-01

    of fuel particles in a boiler. A cold pilot scale model of a circulating fluidized bed combustor was used. Here sand was recirculated by means of air. Pressure measurements along the riser determined suspension density. A radioactive tracking facility to determined the dynamic picture of the particle...... trajectories in the simulated boiler. In the splash zone, closest to the secondary air inlet an exponential decay in the solids suspension density with the riser height was observed. A transport zone was characterized by an exponential decay in the solids suspension but with a smaller decay constant...

  16. Using a modified Lane’s relation in local bed scouring studies in aluvial bed

    Directory of Open Access Journals (Sweden)

    Marta Kiraga

    2016-12-01

    Full Text Available Numerous approaches to the local scour studies have been developed. The research aim was to verify modified Lane’s relation in scope of local scouring phenomenon basing on laboratory studies results. Original Lane’s relation [1955] is applicable in dynamic balance conditions in alluvial rivers context. Original form is not an equation, but a qualitative expression which cannot be directly used to estimate the influence of a change in one parameter on the magnitude of others. Modified version allows transforming it into equation for dynamic equilibrium conditions in steady flow assumption and gives a new opportunity to this principle application. Two physical models of laboratory channel with rectangular cross-sections and glass panels have been constructed, with totally or partially sandy bottom. Model I assumed non-continual sediment transport, because of model construction, i.e. the solid bottom transforms into sandy bottom in the intake part. Model II assumed water structure (the weir with four slots introducing into laboratory channel with solid bottom in its region, whereas the rest of channel was filled with sand above and below structure, i.e. continuity of sediment transport was assured. Results of research confirmed modified Lane’s relation usability in scope of local scouring phenomenon description in dynamic equilibrium conditions of alluvial sandy bed.

  17. Metabolic Resistance in Bed Bugs

    Directory of Open Access Journals (Sweden)

    Omprakash Mittapalli

    2011-03-01

    Full Text Available Blood-feeding insects have evolved resistance to various insecticides (organochlorines, pyrethroids, carbamates, etc. through gene mutations and increased metabolism. Bed bugs (Cimex lectularius are hematophagous ectoparasites that are poised to become one of the major pests in households throughout the United States. Currently, C. lectularius has attained a high global impact status due to its sudden and rampant resurgence. Resistance to pesticides is one factor implicated in this phenomenon. Although much emphasis has been placed on target sensitivity, little to no knowledge is available on the role of key metabolic players (e.g., cytochrome P450s and glutathione S-transferases towards pesticide resistance in C. lectularius. In this review, we discuss different modes of resistance (target sensitivity, penetration resistance, behavioral resistance, and metabolic resistance with more emphasis on metabolic resistance.

  18. Particle Bed Reactor engine technology

    International Nuclear Information System (INIS)

    Sandler, S.; Feddersen, R.

    1992-01-01

    This paper discusses the Particle Bed Reactor (PBR) based propulsion system being developed under the Space Nuclear Thermal Propulsion (SNTP) program. A PBR engine is a light weight, compact propulsion system which offers significant improvement over current technology systems. Current performance goals are a system thrust of 75,000 pounds at an Isp of 1000 sec. A target thrust to weight ratio (T/W) of 30 has been established for an unshielded engine. The functionality of the PBR, its pertinent technology issues and the systems required to make up a propulsion system are described herein. Accomplishments to date which include hardware development and tests for the PBR engine are also discussed. This paper is intended to provide information on and describe the current state-of-the-art of PBR technology. 4 refs

  19. Particle Bed Reactor engine technology

    Science.gov (United States)

    Sandler, S.; Feddersen, R.

    1992-03-01

    This paper discusses the Particle Bed Reactor (PBR) based propulsion system being developed under the Space Nuclear Thermal Propulsion (SNTP) program. A PBR engine is a light weight, compact propulsion system which offers significant improvement over current technology systems. Current performance goals are a system thrust of 75,000 pounds at an Isp of 1000 sec. A target thrust to weight ratio (T/W) of 30 has been established for an unshielded engine. The functionality of the PBR, its pertinent technology issues and the systems required to make up a propulsion system are described herein. Accomplishments to date which include hardware development and tests for the PBR engine are also discussed. This paper is intended to provide information on and describe the current state-of-the-art of PBR technology.

  20. Building Controls Virtual Test Bed

    Energy Technology Data Exchange (ETDEWEB)

    2008-04-01

    The Building Controls Virtual Test Bed (BCVTB) is a modular software environment that is based on the Ptolemy II software environment. The BCVTB can be used for design and analysis of heterogenous systems, such as building energy and controls systems. Our additions to Ptolemy II allow users to Couple to Ptolemy II simulation software such as EnergyPlus, MATLAB/Simulink or Dymola for data exchange during run-time. Future versions of the BCVTS will also contain an interface to BACnet which is a communication protocol for building Control systems, and interfaces to digital/analog converters that allow communication with controls hardware. Through Ptolemy II, the BCVTB provides a graphical model building environment, synchronizes the exchanged data and visualizes the system evolution during run- time.

  1. Flue gas desulfurization by rotating beds

    Energy Technology Data Exchange (ETDEWEB)

    Gardner, N.; Keyvani, M.; Coskundeniz, A.

    1992-01-01

    The operating and mass transfer characteristics of rotating foam metal beds were studied to determine the potential for flue gas desulfurization. This is a final technical report on the work supported by DOE [number sign]FG22-87-PC79924. The report is divided into two sections, Part 1 deals primarily with the operating characteristics of rotating beds, and Part 2 covers the mass transfer characteristics of S0[sub 2] absorption in water-lime slurries. Rotating foam metal beds are in essence packed towers operated in high gravitational fields. The foam metal bed is in the form of a cylindrical donut, or torus, and is rotated to produced the high centrifugal forces. The liquid phase enters the bed at the inner surface of the torus and is pulled by the field through the bed. Gas flows countercurrent to the liquid. The bed packing can have a very large specific surface areas and not flood. Possible benefits include much smaller height of a transfer unit resulting in smaller equipment and supporting structures, reduced solvent inventory, faster response with improved process control, reduced pressure drop, and shorter startup and shut-down times. This work is concerned broadly with the operating characteristics of rotating beds, the objectives being to (1) determine the pressure drop through the rotating bed; (2) determine the power required to operate the beds, (3) investigate the residence time distribution of the liquid phase in the beds; and (4) determine the mass transfer coefficients of S0[sub 2] absorption. Three packings of differing specific surface areas were studied, with areas ranging from 656 to 2952 m[sub 2]/m[sub 3]. Liquid flow rates to 36 kg/s*m[sub 2], gas flow rate to 2.2 kg/s*m[sub 2], and gravitational fields to 300 g were covered in this study.

  2. Road transport of cattle, swine and poultry in North America and its impact on animal welfare, carcass and meat quality: a review.

    Science.gov (United States)

    Schwartzkopf-Genswein, K S; Faucitano, L; Dadgar, S; Shand, P; González, L A; Crowe, T G

    2012-11-01

    This paper reviews the effects of road transport on the welfare, carcass and meat quality of cattle, swine and poultry in North America (NA). The main effects of loading density, trailer microclimate, transport duration, animal size and condition, management factors including bedding, ventilation, handling, facilities, and vehicle design are summarized by species. The main effects listed above all have impacts on welfare (stress, health, injury, fatigue, dehydration, core body temperature, mortality and morbidity) and carcass and meat quality (shrink, bruising, pH, color defects and water losses) to varying degrees. It is clear that the effect of road transport is a multi-factorial problem where a combination of stressors rather than a single factor is responsible for the animal's well-being and meat quality post transport. Animals least fit for transport suffer the greatest losses in terms of welfare and meat quality while market ready animals (in particular cattle and pigs) in good condition appear to have fewer issues. More research is needed to identify the factors or combination of factors with the greatest negative impacts on welfare and meat quality relative to the species, and their size, age and condition under extreme environmental conditions. Future research needs to focus on controlled scientific assessments, under NA conditions, of varying loading densities, trailer design, microclimate, and handling quality during the transport process. Achieving optimal animal well-being, carcass and meat quality will entirely depend on the quality of the animal transport process. Crown Copyright © 2012. Published by Elsevier Ltd. All rights reserved.

  3. Preliminary Results on Sediment Sorting Under Intense Bedload Transport

    Science.gov (United States)

    Hernandez Moreira, R. R.; Vautin, D.; Mathews, S. L.; Kuprenas, R.; Viparelli, E.

    2014-12-01

    Previous experiments show that parallel-laminated deposits are emplaced under upper plane bed regime by the migration of small-amplitude, long-wavelength bedforms. The present research focuses on how sediment is sorted under upper plane bed and sheet flow transport regimes, and whether parallel-lamination is inhibited during sheet flow transport. The problem of studying the sorting of sediment under so intense transport conditions is plagued by the uncertainties related to flow resistances and bedload transport rates. We simplify the problem by first running the experiments with uniform sediment, to establish a baseline that will aid in the design of the experiments with poorly sorted material. We are running experiments at the Hydraulics Laboratory of the Department of Civil and Environmental Engineering at the University of South Carolina in Columbia, in a unidirectional sediment-feed flume, 9 meters long by 0.2 meters wide, of which 7 meters are used as test section. During the experiments, water surface and bed elevations are periodically measured to characterize the global parameters of the flow, e.g. mean flow velocity and bed shear stress. When the flow and the sediment transport reach conditions of mobile bed equilibrium, bed elevation fluctuations are measured with ultrasonic transducer systems at six fixed locations. Channel bed aggradation is then induced by slowly raising the tail gate of the flume such that there is no change in transport regime, as confirmed by additional measurements of water surface and bed elevation and bed elevation fluctuations. Preliminary observations under upper plane bed regime show the formation of the small-amplitude and long-wavelength bedforms, as well as hints of parallel lamination in the deposits. In the near future we aim to achieve sheet flow transport conditions with both uniform and non-uniform grain size distributions to look at the internal structure of the emplaced deposit.

  4. Pulsed atmospheric fluidized bed combustion

    Energy Technology Data Exchange (ETDEWEB)

    1989-11-01

    In order to verify the technical feasibility of the MTCI Pulsed Atmospheric Fluidized Bed Combustor technology, a laboratory-scale system was designed, built and tested. Important aspects of the operational and performance parameters of the system were established experimentally. A considerable amount of the effort was invested in the initial task of constructing an AFBC that would represent a reasonable baseline against which the performance of the PAFBC could be compared. A summary comparison of the performance and emissions data from the MTCI 2 ft {times} 2 ft facility (AFBC and PAFBC modes) with those from conventional BFBC (taller freeboard and recycle operation) and circulating fluidized bed combustion (CFBC) units is given in Table ES-1. The comparison is for typical high-volatile bituminous coals and sorbents of average reactivity. The values indicated for BFBC and CFBC were based on published information. The AFBC unit that was designed to act as a baseline for the comparison was indeed representative of the larger units even at the smaller scale for which it was designed. The PAFBC mode exhibited superior performance in relation to the AFBC mode. The higher combustion efficiency translates into reduced coal consumption and lower system operating cost; the improvement in sulfur capture implies less sorbent requirement and waste generation and in turn lower operating cost; lower NO{sub x} and CO emissions mean ease of site permitting; and greater steam-generation rate translates into less heat exchange surface area and reduced capital cost. Also, the PAFBC performance generally surpasses those of conventional BFBC, is comparable to CFBC in combustion and NO{sub x} emissions, and is better than CFBC in sulfur capture and CO emissions even at the scaled-down size used for the experimental feasibility tests.

  5. Solute dispersion in open channel flow with bed absorption

    Science.gov (United States)

    Wang, Ping; Chen, G. Q.

    2016-12-01

    Reactive solute dispersion is of essential significance in various ecological and environmental applications. It is only qualitatively known that boundary absorption depletes pollutant around the boundary and reduces the concentration nearby. All the existing studies on this topic have been focused on the longitudinally distributed mean concentration, far from enough to fully characterize the transport process with tremendous cross-sectional concentration nonuniformity. This work presents an analytical study of the evolution of two-dimensional concentration distribution for solute dispersion in a laminar open channel flow with bed absorption. The fourth order Aris-Gill expansion proposed in our previous study (Wang and Chen, 2016b) is further extended for the case with bed absorption to cover the transitional effects of skewness and kurtosis. Results reveal the extremely nonuniform cross-sectional concentration distribution, and demonstrate that concentration at the bed instead of the mean should be used for reliable quantification of the absorption flux. The accurate two-dimensional concentration distribution presented in this study brings important environmental implications such as risk assessment associated with peak concentration position and duration of toxic pollutant cloud in open channel waters.

  6. Enhanced Productivity of Chemical Processes Using Dense Fluidized Beds

    Energy Technology Data Exchange (ETDEWEB)

    Sibashis Banerjee; Alvin Chen; Rutton Patel; Dale Snider; Ken Williams; Timothy O' Hern; Paul Tortora

    2008-02-29

    The work detailed in this report addresses Enabling Technologies within Computational Technology by integrating a “breakthrough” particle-fluid computational technology into traditional Process Science and Engineering Technology. The work completed under this DOE project addresses five major development areas 1) gas chemistry in dense fluidized beds 2) thermal cracking of liquid film on solids producing gas products 3) liquid injection in a fluidized bed with particle-to-particle liquid film transport 4) solid-gas chemistry and 5) first level validation of models. Because of the nature of the research using tightly coupled solids and fluid phases with a Lagrangian description of the solids and continuum description of fluid, the work provides ground-breaking advances in reactor prediction capability. This capability has been tested against experimental data where available. The commercial product arising out of this work is called Barracuda and is suitable for a wide (dense-to-dilute) range of industrial scale gas-solid flows with and without reactions. Commercial applications include dense gas-solid beds, gasifiers, riser reactors and cyclones.

  7. Laboratory study of gravel-bed cluster formation and disintegration

    Science.gov (United States)

    Heays, K. G.; Friedrich, H.; Melville, B. W.

    2014-03-01

    Increased knowledge of clusters is essential for the understanding of sediment transport behavior and the monitoring and protection of aquatic life. A physical study using graded river gravels is conducted in a laboratory environment. Using photogrammetry and painted gravels, a cluster identification tool (CIT) is developed based on image subtraction between subsequent frames, allowing identification of any stable areas and groups of particles on the bed. This is combined with digital particle tracking (DPT) to present a novel approach for monitoring the formation and disintegration of clusters. Clusters from graded gravels are formed successfully during the experimental stage, allowing investigation into the complex dynamic behavior of cluster formation and disintegration in a simulated natural environment. Various anchor stone arrangements are used in the experiments. However, only about one fifth of the potential anchor stones on the bed surface enable cluster formation. In general, clusters classified as "typical" and "heap" are most common. Inspection of temporal cluster coverage of the test-bed surface shows that the proportion of clusters present on the surface tends to grow with time. Maximum cluster surface coverage of between 5% and 34% is observed. In addition, particles entering and departing from clusters are monitored. Most commonly, particles enter from directly upstream of the cluster, however >20% of particles approach from a direction >20 deg from the streamwise direction. Approximately 35% of all particles directly upstream of a cluster bypass the cluster.

  8. Load rating and retrofit testing of bridge timber piles subjected to eccentric loading.

    Science.gov (United States)

    2012-11-01

    This report first evaluated the load rating procedure currently in use by the Illinois Department of Transportation (IDOT) for rating timber : piles supporting multiple-span, simply supported bridges. For simplicity, these piles are often rated under...

  9. Absorber rod for nuclear reactors in a pebble bed of spherical operating elements

    International Nuclear Information System (INIS)

    Reinstein, D.; Gnutzmann, H.

    1978-01-01

    The claim refers to the constructional configuration of an absorber rod, whose and penetrating into the pebble bed has an opening to reduce the fracture rate, so that the operating elements can escape into a channel within the absorber rod. To suit this to the direction of movement of the elements a part of the end of the rod is flexibly connected to the hollow absorber rod via a joint. In this way the mechanical load of the element particles is reduced and simultaneously one achieves that much lower force is required to insert the absorber rod into the pebble bed. (UA) [de

  10. Flue Gas Emissions from Fluidized Bed Combustion

    NARCIS (Netherlands)

    Bramer, E.A.; Valk, M.

    1995-01-01

    During the past decades fluidized bed coal combustion was developed as a technology for burning coal in an effective way meeting the standards for pollution control. During the earlier years of research on fluidized bed combustion, the potential for limiting the S02 emission by adding limestone to

  11. Print a Bed Bug Card - (Single Cards)

    Science.gov (United States)

    Two sets of business-card-sized lists of tips for recognizing bed bugs and the signs of an infestation, including a photo of bed bugs to assist identification. One card is for general use around home or office, the other for travelers.

  12. Variation in Sediment Mobility and the Active Width in Gravel-bed Braided Rivers

    Science.gov (United States)

    Peirce, S.; Leduc, P.; Ashmore, P.

    2016-12-01

    The complex and dynamic morphology of gravel-bed braided rivers is fundamentally a consequence of spatially and temporally variable sediment transport. For example, while braided rivers have multiple channels conveying water, few ( 1-2) channels convey sediment and only a narrow area (morphological active width) of those active channels transport bedload. To investigate the relationship between the morphological active width and bedload transport, a 1:30 physical-scale model of a gravel-bed river (D50 = 1.3mm) with adjustable discharge (0.7-2.1l/s) was used to simulate three experimental hydrographs. The physical model represents a braided river with 1.5% slope, medium gravel, and discharges between 4-13 m3s-1. High-resolution (± 1.15 mm) DEMs of the dry-bed surface were generated at 15 minute intervals using digital photogrammetry and the software program Agisoft PhotoScan. The morphological active width was quantified by subtracting successive DEMs to highlight areas and volumes of erosion and deposition. Bedload transport and grain size distribution were independently measured by accumulating bedload in baskets at the downstream outlet. Results show that while bedload transport and the active width are spatially and temporally variable, they both increase with increasing discharge above a lower threshold of 1.1l/s. Exceptions from this trend suggest that antecedent morphological conditions, such as migrating bars and bedload sheets, contribute to the inherent spatio-temporal variability. Grain size analysis shows that bedload transport moves from partial mobility towards equal mobility with increasing discharge, even in these dynamic multi-channel river systems. Understanding the relationships between channel morphology, bedload transport and mobility, and the active width will improve predictions of bedload transport rate in complex rivers and provide a more complete understanding of morph-dynamic processes in gravel-bed rivers.

  13. 49 CFR 575.103 - Truck-camper loading.

    Science.gov (United States)

    2010-10-01

    ... Transportation Other Regulations Relating to Transportation (Continued) NATIONAL HIGHWAY TRAFFIC SAFETY... loading of the camper and to provide more detailed loading information in the owner's manual. This section... manufacturer as the cargo-carrying capacity, in pounds or kilograms, of a vehicle, exclusive of the weight of...

  14. Determination of true bed thickness using folded bed model and borehole data

    Energy Technology Data Exchange (ETDEWEB)

    Xu, S.S.; Velasquillo-Martinez, L.G.; Grajales-Nishimura, J.M.; Murillo-Muneton, G. [Inst. Mexicano del Petroleo, Mexico City (Mexico); Garcia-Hernandez, J. [Petroleos Mexicanos Exploracion y Produccion, Tamaulipas (Mexico); Nieto-Samaniego, A.F. [Nacional Autonoma de Mexico Univ., Veracruz (Mexico). Centro de Geociencias

    2007-11-15

    The actual thickness of a given formation perpendicular to the bedding plane is known as the true bed thickness. Petroleum engineers rely on information regarding true bed thickness, particularly in dipping beds and in deviated holes because reservoir volume and isochore maps depend on these properties and not on the measured thickness. True bed thickness can be estimated from information gathered from well logs such as the dipmeter and borehole images. However, when deviations and dips exceed 10 degrees, corrections are needed. In this paper, a folded bed model was proposed to calculate the true bed thickness in the subsurface utilizing well log data. The value of true bed thickness (t) was shown to depend on the angle and the direction of the dip of the measured formation, as well as the drift angle and azimuth of the borehole. A case study from the Cantarell oil field in the southern Gulf of Mexico, offshore Campeche, was used to test the folded bed method. The model was shown to yield more uniform spatial change of the values of t, compared to the monoclinal bed model that often overestimates the average value of t. The maximum relative deviation of t from the monoclinal bed model reached 22.3 per cent and the maximum absolute deviation of t reached 34.5 m. The key factors that influence the values of t were found to be the bed dip, the dip difference between the top and base of the bed and the deviated angle of the well. The folded bed model yielded fewer changed values of the true bed thickness. 10 refs., 2 tabs., 9 figs.

  15. Continuous monitoring bed-level dynamics on an intertidal flat: Introducing novel, stand-alone high-resolution SED-sensors

    NARCIS (Netherlands)

    Hu, Z.; Lenting, W.; Van der Wal, D.; Bouma, T.J.

    2015-01-01

    Tidal flat morphology is continuously shaped by hydrodynamic forces, resulting in a highly dynamic bed surface. The knowledge of short-term bed-level changes is important both for assessing sediment transport processes as well as for understanding critical ecological processes, such as vegetation

  16. a novel interconnected fluidised bed for the combined flash pyrolysis of biomass and combustion of char

    NARCIS (Netherlands)

    Janse, A.M.C.; Janse, Arthur M.C.; Biesheuvel, P.M.; Biesheuvel, Pieter Maarten; Prins, W.; van Swaaij, Willibrordus Petrus Maria

    1999-01-01

    A novel system of two adjacent fluidised beds operating in different gas atmospheres and exchanging solids was developed for the combined flash pyrolysis of biomass and combustion of the produced char. Fluidised sand particles (200 μm < dp < 400 μm) are transported from the pyrolysis reactor to the

  17. A novel interconnected fluidised bed for the combined flash pyrolysis of biomass and combustion of char.

    NARCIS (Netherlands)

    Janse, Arthur M.C.; Janse, A.M.C.; Biesheuvel, P.M.; Biesheuvel, Pieter Maarten; Prins, W.; van Swaaij, Willibrordus Petrus Maria

    2000-01-01

    A novel system of two adjacent fluidised beds operating in different gas atmospheres and exchanging solids was developed for the combined flash pyrolysis of biomass and combustion of the produced char. Fluidised sand particles (200 μm < dp < 400 μm) are transported from the pyrolysis reactor to the

  18. Technical and economic assessment of fluidized bed augmented compressed air energy storage system. Volume III. Preconceptual design

    Energy Technology Data Exchange (ETDEWEB)

    Giramonti, A.J.; Lessard, R.D.; Merrick, D.; Hobson, M.J.

    1981-09-01

    A technical and economic assessment of fluidized bed combustion augmented compressed air energy storage systems is presented. The results of this assessment effort are presented in three volumes. Volume III - Preconceptual Design contains the system analysis which led to the identification of a preferred component configuration for a fluidized bed combustion augmented compressed air energy storage system, the results of the effort which transformed the preferred configuration into preconceptual power plant design, and an introductory evaluation of the performance of the power plant system during part-load operation and while load following.

  19. Does Bedding Affect the Airway and Allergy?

    Directory of Open Access Journals (Sweden)

    RW Siebers

    2011-03-01

    Full Text Available Various cross-sectional and longitudinal studies have suggested that synthetic bedding is associated with asthma, allergic rhinitis and eczema while feather bedding seems to be protective. Synthetic bedding items have higher house dust mite allergen levels than feather bedding items. This is possibly the mechanism involved although fungal and bacterial proinflammatory compounds and volatile organic compounds may play a role. In this review we present and discuss the epidemiological evidence and suggest possible mechanisms. Primary intervention studies are required to show whether feather bedding is protective for the development of childhood asthma and allergic diseases while secondary intervention studies are required to potentially reduce symptoms and medication use in subjects with established disease.

  20. Continuous austempering fluidized bed furnace. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Srinivasan, M.N. [Lamar Univ., Beaumont, TX (United States). Dept. of Mechanical Engineering

    1997-09-23

    The intended objective of this project was to show the benefits of using a fluidized bed furnace for austenitizing and austempering of steel castings in a continuous manner. The division of responsibilities was as follows: (1) design of the fluidized bed furnace--Kemp Development Corporation; (2) fabrication of the fluidized bed furnace--Quality Electric Steel, Inc.; (3) procedure for austempering of steel castings, analysis of the results after austempering--Texas A and M University (Texas Engineering Experiment Station). The Department of Energy provided funding to Texas A and M University and Kemp Development Corporation. The responsibility of Quality Electric Steel was to fabricate the fluidized bed, make test castings and perform austempering of the steel castings in the fluidized bed, at their own expense. The project goals had to be reviewed several times due to financial constraints and technical difficulties encountered during the course of the project. The modifications made and the associated events are listed in chronological order.