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Sample records for bed slope effects

  1. Influence of bedforms on the transverse bed slope effect

    NARCIS (Netherlands)

    Baar, A.W.; Kleinhans, M.G.; Smit, Jaco; Uijttewaal, Wim

    2016-01-01

    The deflection of sediment transport on a transverse slope due to gravity determines the large scale morphology by influencing bar dimensions and bifurcation dynamics. However, existing transverse bed slope predictors in morphodynamic models are based on a small range of flow conditions and sediment

  2. Bed Slope Effect on Non-uniform Flow through Porous Media

    Science.gov (United States)

    Bhanu Prakasham Reddy, N.; Krishnaiah, S.; Ramakrishna Reddy, M.

    2016-09-01

    The tilting angle or bed slope (φ) effect on piezometric head was studied in a tilting angle converging permeameter for different rate of flows and for different bed slopes or tilting angles (φ) and the equipotential lines of piezometric head are depicted pictorially to establish the suitability of the convergent flow assumption and have a proper insight into the subject of seepage flow. The porosity effect is considered while computing seepage velocity (V), linear parameter, non-linear parameter, increases with decrease of porosity (N) and increases with decrease of angle of inclination. In order to meet the objective of this study, a crushed rock of size 7.30 mm was used as media and water as fluid, to develop curves relating friction factor (FR) and Reynolds number (RR) for different ratios of width using hydraulic radius (R) as characteristic length for different bed slopes or tilting angles (φ). The effect of varying tilting angles (φ) on head loss of fluid flow through porous media when packed between convergent boundaries for different ratios of width (B1/B2) was studied and inferred that tilting angles (φ) have a significant effect on the non uniform flow.

  3. Irregular Wave Forces on Monopile Foundations. Effect af Full Nonlinearity and Bed Slope

    DEFF Research Database (Denmark)

    Schløer, Signe; Bredmose, Henrik; Bingham, Harry B.

    2011-01-01

    Forces on a monopile from a nonlinear irregular unidirectional wave model are investigated. Two seabed profiles of different slopes are considered. Morison’s equation is used to investigate the forcing from fully nonlinear irregular waves and to compare the results with those obtained from linear...... wave theory and with stream function wave theory. The latter of these theories is only valid on a flat bed. The three predictions of wave forces are compared and the influence of the bed slope is investigated. Force-profiles of two selected waves from the irregular wave train are further compared...... with the corresponding forceprofiles from stream function theory. The results suggest that the nonlinear irregular waves give rise to larger extreme wave forces than those predicted by linear theory and that a steeper bed slope increases the wave forces both for linear and nonlinear waves. It is further found...

  4. Bed slope effects on turbulent wave boundary layers: 2. Comparison with skewness, asymmetry, and other effects

    DEFF Research Database (Denmark)

    Fuhrman, David R.; Fredsøe, Jørgen; Sumer, B. Mutlu

    2009-01-01

    investigated for each component, and skewness and asymmetry are demonstrated to promote largely negative streaming velocities, consistent with earlier work. For hydraulically smooth cases, however, a thin region of positive streaming is revealed in the viscous sublayer which is effectively absent...... in hydraulically rough conditions. Cross-shore boundary layer dynamics are generally acknowledged to be a complicated combination of numerous competing physical processes, and this work is among few to systematically compare a number of these. It is hoped that the results will be useful in assessing which...

  5. Full-Wave Algorithm to Model Effects of Bedding Slopes on the Response of Subsurface Electromagnetic Geophysical Sensors near Unconformities

    CERN Document Server

    Sainath, Kamalesh

    2015-01-01

    We propose a full-wave pseudo-analytical numerical electromagnetic (EM) algorithm to model subsurface induction sensors, traversing planar-layered geological formations of arbitrary EM material anisotropy and loss, which are used, for example, in the exploration of hydrocarbon reserves. Unlike past pseudo-analytical planar-layered modeling algorithms that impose parallelism between the formation's bed junctions however, our method involves judicious employment of Transformation Optics techniques to address challenges related to modeling arbitrarily-oriented, relative slope (i.e., tilting) between said junctions. The algorithm exhibits this flexibility, both with respect to anisotropy in the formation layers as well as junction tilting, via employing special planar slabs that coat each "flattened" (i.e., originally tilted) planar interface, locally redirecting the incident wave within the coating slabs to cause wave fronts to interact with the flattened interfaces as if they were still tilted with a specific, ...

  6. Bed slope effects on turbulent wave boundary layers: 1. Model validation and quantification of rough-turbulent results

    DEFF Research Database (Denmark)

    Fuhrman, David R.; Fredsøe, Jørgen; Sumer, B. Mutlu

    2009-01-01

    are first validated against hydraulically smooth and rough data from flat bed experiments in the form of wave friction factor diagrams. The results show that the model provides acceptable accuracy for wave orbital amplitude to roughness length ratios a/k(N) >= 20. Validation against experimental...

  7. 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.

  8. Entrainment, motion, and deposition of coarse particles transported by water over a sloping mobile bed

    Science.gov (United States)

    Heyman, J.; Bohorquez, P.; Ancey, C.

    2016-10-01

    In gravel bed rivers, bed load transport exhibits considerable variability in time and space. Recently, stochastic bed load transport theories have been developed to address the mechanisms and effects of bed load transport fluctuations. Stochastic models involve parameters such as particle diffusivity, entrainment, and deposition rates. The lack of hard information on how these parameters vary with flow conditions is a clear impediment to their application to real-world scenarios. In this paper, we determined the closure equations for the above parameters from laboratory experiments. We focused on shallow supercritical flow on a sloping mobile bed in straight channels, a setting that was representative of flow conditions in mountain rivers. Experiments were run at low sediment transport rates under steady nonuniform flow conditions (i.e., the water discharge was kept constant, but bed forms developed and migrated upstream, making flow nonuniform). Using image processing, we reconstructed particle paths to deduce the particle velocity and its probability distribution, particle diffusivity, and rates of deposition and entrainment. We found that on average, particle acceleration, velocity, and deposition rate were responsive to local flow conditions, whereas entrainment rate depended strongly on local bed activity. Particle diffusivity varied linearly with the depth-averaged flow velocity. The empirical probability distribution of particle velocity was well approximated by a Gaussian distribution when all particle positions were considered together. In contrast, the particles located in close vicinity to the bed had exponentially distributed velocities. Our experimental results provide closure equations for stochastic or deterministic bed load transport models.

  9. EXPERIMENTAL STUDY ON INCIPIENT MOTION OF SEDIMENT PARTICLES ON GENERALIZED SLOPING FLUVIAL BEDS

    Institute of Scientific and Technical Information of China (English)

    Subhasish DEY

    2001-01-01

    This paper presents an experimental investigation on incipient motion of non-cohesive uniform sediment under a steady-uniform stream flow on generalized sloping fluvial beds (combined lateral and stream-wise slope). The characteristic parameters affecting the incipient motion of sediment particles, identified based on the physical reasoning and dimensional analysis, are the threshold shear stress ratio (ratio of threshold shear stress for sloping bed to that for horizontal bed), lateral slope,stream-wise slope and angle of repose of sediment particles. Experiments were carried out in two ducts (closed-conduit flow) having section of semicircular invert with three types of sediments. In an open channel flow (laboratory flume study), the uniform flow is a difficult, if not impossible,proposition for a steeply sloping channel and is impossible to obtain in an adversely sloping channel.To avoid this problem, the tests were conducted with a closed-conduit flow. Equation of critical bed shear stress for the initial movement of sediment particles on generalized sloping beds was obtained using the experimental data.

  10. A Three-Point Method for Separating Incident and Reflected Waves over A Sloping Bed

    Institute of Scientific and Technical Information of China (English)

    CHANG Hsien-Kuo

    2002-01-01

    This study presents a three-point method for separating incident and reflected waves to explain normally incident waves' propagating over a sloping bed. Linear wave shoaling is used to determine changes in wave amplitude and phase in response to variations of bathymetry. The wave reflection coefficient and incident amplitude are estimated from wave heights measured at three fixed wave gauges with unequal spacing. Sensitivity analysis demonstrates that the proposed method can predict the reflection and amplitude of waves over a sloping bed more accurately than the two-point method.

  11. NUMERICAL INVESTIGATION ON MUD BED-GENERATION AND IMPACTING A WALL ALONG A SLOPE

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    In this paper mud was treated as the Bingham fluid. In staggered grids, two-dimensional incompressible Navier-Stokes equations for non-Newtonian fluid was solved by the MAC method. Numerical simulations were conducted on mud bed-generating phenomenon and mud impacting a wall along a slope. The distributions of free surface, pressure and velocity of mud and water were obtained. The results indicate that the computed layer thickness of mud bed almost equals the theoretically predicted value. Because of the differences in constitutive relationship, the distributions of free surface are different for water and mud. The distortion of water free surface is much more complicated.

  12. Wave interaction with large roughness elements on an impermeable sloping bed

    DEFF Research Database (Denmark)

    Jensen, Bjarne; Christensen, Erik Damgaard; Sumer, B. Mutlu

    2012-01-01

    is on the details in the porous core flow and the armour layer flow i.e. the interaction between the two flow domains and the effect on the armour layer stability. In order to isolate the processes involved with the flow in the porous core the investigations are first carried out with a completely impermeable bed...

  13. [Effects of slope gradient on slope runoff and sediment yield under different single rainfall conditions].

    Science.gov (United States)

    He, Ji-Jun; Cai, Qiang-Guo; Liu, Song-Bo

    2012-05-01

    Based on the field observation data of runoff and sediment yield produced by single rainfall events in runoff plots, this paper analyzed the variation patterns of runoff and sediment yield on the slopes with different gradients under different single rainfall conditions. The differences in the rainfall conditions had little effects on the variation patterns of slope runoff with the gradient. Under the conditions of six different rainfall events in the study area, the variation patterns of slope runoff with the gradient were basically the same, i. e., the runoff increased with increasing gradient, but the increment of the runoff decreased slightly with increasing gradient, which was mainly determined by the infiltration flux of atmospheric precipitation. Rainfall condition played an important role on the slope sediment yield. Generally, there existed a critical slope gradient for slope erosion, but the critical gradient was not a fixed value, which varied with rainfall condition. The critical slope gradient for slope erosion increased with increasing slope gradient. When the critical slope gradient was greater, the variation of slope sediment yield with slope gradient always became larger.

  14. Effects of grapevine root density and reinforcement on slopes prone to shallow slope instability

    Science.gov (United States)

    Meisina, Claudia; Bordoni, Massimiliano; Bischetti, Gianbattista; Vercesi, Alberto; Chiaradia, Enrico; Cislaghi, Alessio; Valentino, Roberto; Bittelli, Marco; Vergani, Chiara; Chersich, Silvia; Giuseppina Persichillo, Maria; Comolli, Roberto

    2016-04-01

    Slope erosion and shallow slope instabilities are the major factors of soil losses in cultivated steep terrains. These phenomena also cause loss of organic matter and plants nutrients, together with the partial or total destruction of the structures, such as the row tillage pattern of the vineyards, which allow for the plants cultivation. Vegetation has long been used as an effective tool to decrease the susceptibility of a slope to erosion and to shallow landslides. In particular, the scientific research focused on the role played by the plant roots, because the belowground biomass has the major control on the potential development of soil erosion and of shallow failures. Instead, a comprehensive study that analyzes the effects of the roots of agricultural plants on both soil erosion and slope instability has not been carried out yet. This aspect should be fundamental where sloped terrains are cultivated with plants of great economical relevance, as grapevine. To contribute to fill this gap, in this study the features of root density in the soil profile have been analyzed in slopes cultivated with vineyards, located on a sample hilly area of Oltrepò Pavese (northern Italy). In this area, the viticulture is the most important branch of the local economy. Moreover, several events of rainfall-induced slope erosion and shallow landslides have occurred in this area in the last 6 years, causing several economical damages linked to the destruction of the vineyards and the loss of high productivity soils. Grapevine root distribution have been measured in different test-site slopes, representative of the main geological, geomorphological, pedological, landslides distribution, agricultural features, in order to identify particular patterns on root density that can influence the development of slope instabilities. Roots have been sampled in each test-site for characterizing their strength, in terms of the relation between root diameter and root force at rupture. Root

  15. The effect of beach slope on tidal influenced saltwater intrusion

    Science.gov (United States)

    Zhao, Z.; Shen, C.; Jin, G.; Xin, P.; Hua, G.; Tao, X.; Zhao, J.

    2015-12-01

    Beach slope changes the tidal induced saltwater-freshwater circulations in coastal aquifers. However, the effect of beach slope on tidal influenced saltwater-freshwater mixing process is far from understood. Based on sand flume experiments and numerical simulations, we investigated the intrusion process of saltwater into freshwater under tidal forcing and variable beach slopes. The sand flume experiment results show that milder slope induces larger upper saline plume (USP) and seaward salt wedge interface (SWI) under tidal forcing. While, the steady state SWI keeps stagnant with different beach slopes. Consistent with the previous research, our numerical simulations also show a lager flux exchange across the milder beach induced by the tidal fluctuations. The groundwater table fluctuates more intensify with deeper beach slope. The next step of our study will pay attention to the effect of beach slope on the instability of USP which induces the salt-fingering flow.

  16. Effective Thermal Conductivity of Adsorbent Packed Beds

    Science.gov (United States)

    Mori, Hideo; Hamamoto, Yoshinori; Yoshida, Suguru

    The effective thermal conductivity of adsorbent packed beds of granular zeolite 13X and granular silica gel A in the presence of stagnant steam or air was measured under different conditions of the adsorbent bed temperature, particle size and filler-gas pressure. The measured effective thermal conductivity showed to become smaller with decreasing particle size or decreasing pressure, but it was nearly independent of the bed temperature. When steam was the filler-gas, the rise in the thermal conductivity of the adsorbent particles due to steam adsorption led to the increase in the effective thermal conductivity of the bed, and this effect was not negligible at high steam pressure for the bed of large particle size. It was found that both the predictions of the effective thermal conductivity by the Hayashi et al.'s model and the Bauer-Schlünder model generally agreed well with the measurements, by considering the particle thermal conductivity rise due to steam adsorption. The thermal conductivity of a consolidated bed of granular zeolite 13X was also measured, and it was found to be much larger than that of the packed bed especially at lower pressure. The above prediction models underestimated the effective thermal conductivity of the consolidated bed.

  17. Check dams effects on sediment transport in steep slope flume

    Science.gov (United States)

    Piton, Guillaume; Recking, Alain

    2014-05-01

    Depending on many influences (geology, relief, hydrology, land use, etc.) some mountainous watershed are prone to cause casualties and facilities damages. Large amounts of sediments episodically released by torrents are often the biggest problem in torrent related hazard mitigation. Series of transversal structures as check dams and ground sills are often used in the panel of risk mitigation technics. A large literature exits on check dams and it mainly concerns engineering design, e.g. toe scouring, stability stress diagram, changes in upper and lower reaches equilibrium slopes. Check dams in steep slope rivers constitute fixed points in the bed profile and prevent general bed incision. However their influence on sediment transport once they are filled is not yet clear. Two flume test campaigns, synthetize in Table 1, were performed to investigate this question: Table 1 : experiment plan Run (duration) Ref1 (50h)CD1a (30h)CD1b (30h)Ref2 (92h)CD2 (18h) Solid feeding discharge (g.s^-1) 44 44 44 60 60 Number of check dams none 1 3 none 2 A nearly 5-m-long, 10-cm-wide and 12%-steep flume was used. The water discharge was set to 0,55 l/s in all runs. A mixture of poorly sorted natural sediments with diameters between 0.8 and 40 mm was used. An open solid-discharge-feeding circuit kept the inlet sediment flux constant during all experiments. As both feeding rates did not present variation, changes in outlet solid discharge were assumed to be due to bed variations in the bed storage. We observed strong fluctuations of solid flux and slope in each reaches of all runs between: (i) steep aggradating armoured bed and (ii) less steep and finer bed releasing bedload sheets during erosion events and inducing bedload pulses. All experiments showed consistent results: transported volume associated with erosion event decreased with the length between two subsequent check dams. Solid transversal structures shorten the upstream erosion-propagation and avoid downstream change in the

  18. Effects of rainfall infiltration on deep slope failure

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    With the finite element method and the limit equilibrium method, a numerical model has been established for examining the effects of rainfall infiltration on the stability of slopes. This model is able to availably reflect the variations in pore pressure field in slopes, dead weight of soil, and the softening of soil strength caused by rainfall infiltration. As a case study, an actual landslide located at the Nongji Jixiao in Chongqing is studied to analyze the effects of rainfall infiltration on the seepage field and the slope stability. The simulated results show that a deep slope failure is prone to occur when rainfall infiltration will lead to a remarkable variation in the seepage field, in particular, for large range pore water pressure increase in slopes.

  19. Effects of rainfall infiltration on deep slope failure

    Institute of Scientific and Technical Information of China (English)

    SUN JianPing; LIU QingQuan; LI JiaChun; AN Yi

    2009-01-01

    With the finite element method and the limit equilibrium method, a numerical model has been estab-lished for examining the effects of rainfall infiltration on the stability of slopes. This model is able to availably reflect the variations in pore pressure field in slopes, dead weight of soil, and the softening of soil strength caused by rainfall infiltration. As a case study, an actual landslide located at the Nongji Jixiao in Chongqing is studied to analyze the effects of rainfall infiltration on the seepage field and the slope stability. The simulated results show that a deep slope failure is prone to occur when rainfall infiltration will lead to a remarkable variation in the seepage field, in particular, for large range pore water pressure increase in slopes.

  20. 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

  1. Stability analysis of slopes of expansive soils considering rainfall effect

    Institute of Scientific and Technical Information of China (English)

    ZHU Fang-cai

    2007-01-01

    Typical failure types of slopes of expansive soils are divided to two kinds: slip in surface layer and slip in shallow layer. Based on total strength law of expansive soils, the relationship between its water content and shear strength inculding cohesion and friction angle, was studied in detail. Acoording to change of water content and depth effect during rainfall, distribution of shear strength in slopes of expansive soils was analyzed. Finally,with a slope of expansive soils in Nanning city of Guangxi Autonomous Region of China as a case, safety factor and slip surface was studied.

  2. The Effect of Fines in Mixed Size Sediment Transport in a Gravel Bed

    Science.gov (United States)

    Hill, K. M.; Baumgardner, S.; Gaffney, J.; Wilcock, P.; Paola, C.

    2011-12-01

    Washload is a widely recognized concept that remains difficult to define. In a gravel-bed river, washload has been defined as those sizes present in the bed only in small proportions. It has also been defined as the portion of transported sediment that has little effect on bed material transport. We experimentally investigate the impact of fine sediment on the mobility and composition of a gravel bed. We conducted flume experiments using a constant water discharge and feed rate of gravel. After reaching steady state, we doubled the feed rate by feeding sediment of finer size, using size ratios from 1:1 to 1:16. As we decrease the size of the fine particles relative to the size of the gravel particles, the system transitions between three regimes. (1) For particle size ratios close to one, the bed slope increases to supply the additional shear stress needed to transport the additional load of similar-sized particles. (2) For intermediate particle size ratios the increased fines content increases the mobility of the sediment mix, resulting in a decreased bed slope. The bed composition is a mix of fine and coarse grains. (3) For the largest particle size ratios (the smallest fines), the additional fines travel primarily in suspension and cause essentially no change in bed slope, though the subsurface becomes clogged with fine sediment. The behavior for near-unity and intermediate particle size ratios can be predicted using a mixed-size bed-material transport formula. For the mixtures with the smallest fine particles, the presence of fines has little effect on the mobility of the gravel and thus the total transport can no longer be predicted with a bed material transport formula. These results provide useful insights concerning the nature of wash load. The effect of sediment feed on gravel mobility and bed slope is not controlled solely by the amount of fines in the bed (the first definition of wash load), but also depends strongly on the relative grain size of the

  3. Formal deduction of the Saint-Venant-Exner model including arbitrarily sloping sediment beds and associated energy

    CERN Document Server

    Fernández-Nieto, E D; Narbona-Reina, G; Zabsonré, J D

    2015-01-01

    In this work we present a deduction of the Saint-Venant-Exner model through an asymptotic analysis of the Navier-Stokes equations. A multi-scale analysis is performed in order to take into account that the velocity of the sediment layer is smaller than the one of the fluid layer. This leads us to consider a shallow water type system for the fluid layer and a lubrication Reynolds equation for the sediment one. This deduction provides some improvements with respect to the classical Saint-Venant-Exner model: (i) the deduced model has an associated energy. Moreover, it allows us to explain why classical models do not have an associated energy and how to modify them in order to recover a model with this property. (ii) The model incorporates naturally a necessary modification that must be taken into account in order to be applied to arbitrarily sloping beds. Furthermore, we show that this modification is different of the ones considered classically, and that it coincides with a classical one only if the solution ha...

  4. The effects of plant density of Melastoma malabathricum on the erosion rate of slope soil at different slope orientations

    Institute of Scientific and Technical Information of China (English)

    Aimee Halim n; Osman Normaniza

    2015-01-01

    abstract Malaysia's cut slopes, especially for road lines accommodation, are prone to erosions and landslides. These problems mainly occur due to lack of vegetation cover and strong erosive forces. In addition, the topography factors have also become a major factor affecting soil degradation. Thus, this study is aimed at determining the effects of planting density of a selected species, namely Melastoma malabathricum;one, two, and three seedlings per box, on the erosion rate at selected slopes of different orientation (morning and evening sun) at the Guthrie Corridor Expressway, Selangor. In six months of observation, treatment with three seedlings/box on the morning sun slope showed a lower erosion rate by 69.2%than those with the same treatment on the evening sun slope. In addition, the treatment of the three seedlings recorded at month six (final observation) had the highest reduction of soil saturation level (STL), by 23.6%. Furthermore, the physiological values of the species studied, grown on the morning sun slope, were higher in terms of stomatal conductance and photosynthetic rate by 12.1%and15.8%(three seedlings/box), respectively. The overall results showed that plant density was inversely related to the STL and erosion rate on the slope. In conclusion, a planting density of three seedlings/box and morning sun orientation gave positive effects on the plant's physiological performance of the slope, reducing the STL, as well as alleviating the erosion rate of slope soils.

  5. Sea-bed biogeochemistry and benthic foraminiferal bathymetric zonation on the slope of the northwest Gulf of Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Loubere, P. (Northern Illinois Univ., DeKalb, IL (United States)); Gary, A. (Unocal Science and Technology Division, Brea, CA (United States)); Lagoe, M. (Univ. of Texas, Austin, TX (United States))

    1993-10-01

    The bathymetric zonation of benthic Foraminiferal taxa in the northwest Gulf of Mexico is summarized and compared to several important environmental parameters measured in boxcores collected along a depth transect. The parameters are bottom water temperature, organic carbon flux, bottom water oxygen content, biogeochemical gradients within the sediments and sedimentation regime. The prominent Foraminiferal boundary between 170 and 200 m is associated with the position of the mudline in the northwest Gulf. Below this, assemblage changes are more gradational with water depth and, between 200 and 600 m, appear to be related to gradients in temperature, oxygen supply and organic carbon flux. Between 600 and 2000 m bathymetric zonation correlates to the organic carbon flux profile. An analysis of sediment pore water geochemistry and sedimentary features in the box-cores shows that there is a progressive change in the vertical distribution and character of potential microhabitats within the sediments down the slope of the northwest Gulf. From 250 to about 700 m water depth the biogenic structures observed in the sediments are abundant and complex, and the biogeochemical gradients in the sediments are steep. The visible complexity and chemical gradients gradually decrease with increasing water depth so that by 1000 m the anoxic boundary is deeper than 7 cm in our boxcores. At water depths greater than 1200 m the sediments are homogeneous, oxidized, hemipelagites. The published Foraminiferal bathymetric zonation of the N.W. Gulf appears to follow this gradient in sedimentary environments which must influence the generation of benthic Foraminiferal assemblages. The gradient is largely controlled by the organic carbon flux to the sea-bed. 42 refs., 8 figs., 3 tabs.

  6. The effect of vibration on bed voidage behaviors in fluidized beds with large particles

    Energy Technology Data Exchange (ETDEWEB)

    Jin, H.; Zhang, J.; Zhang, B.

    2007-07-01

    The effects of vibration parameters, operating conditions and material properties on bed voidage were investigated using an optical fiber probe approach in a vibrating fluidized bed with a diameter of 148 mm. Variables studied included frequency (0-282 s{sup -1}), amplitude (0 mm-1 mm), bed height (0.1 m-0.4 m) as well as four kinds of particles (belonging to Geldart's B and D groups). The axial and radial voidage distribution with vibration is compared with that without vibration, which shows vibration can aid in the fluidization behaviors of particles. For a larger vibration amplitude, the vibration seriously affects bed voidage. The vibration energy can damp out for particle layers with increasing the bed height. According to analysis of experimental data, an empirical correlation for predicting bed voidage, giving good agreement with the experimental data and a deviation within {+-}15%, was proposed. 20 refs., 8 figs., 2 tabs.

  7. The effect of vibration on bed voidage behaviors in fluidized beds with large particles

    Directory of Open Access Journals (Sweden)

    H. Jin

    2007-09-01

    Full Text Available The effects of vibration parameters, operating conditions and material properties on bed voidage were investigated using an optical fiber probe approach in a vibrating fluidized bed with a diameter of 148 mm. Variables studied included frequency (0-282 s-1, amplitude (0 mm-1 mm, bed height (0.1 m-0.4 m as well as four kinds of particles (belonging to Geldart's B and D groups. The axial and radial voidage distribution with vibration is compared with that without vibration, which shows vibration can aid in the fluidization behaviors of particles. For a larger vibration amplitude, the vibration seriously affects bed voidage. The vibration energy can damp out for particle layers with increasing the bed height. According to analysis of experimental data, an empirical correlation for predicting bed voidage, giving good agreement with the experimental data and a deviation within ±15%, was proposed.

  8. CFD-DEM study of effect of bed thickness for bubbling fluidized beds

    Institute of Scientific and Technical Information of China (English)

    Tingwen Li; Pradeep Gopalakrishnana; Rahul Garg; Mehrdad Shahnam

    2012-01-01

    The effect of bed thickness in rectangular fluidized beds is investigated through the CFD-DEM simulations of small-scale systems.Numerical results are compared for bubbling fluidized beds of various bed thicknesses with respect to particle packing,bed expansion,bubble behavior,solids velocities,and particle kinetic energy.Good two-dimensional (2D) flow behavior is observed in the bed having a thickness of up to 20 particle diameters.However,a strong three-dimensional (3D) flow behavior is observed in beds with a thickness of 40 particle diameters,indicating the transition from 2D flow to 3D flow within the range of 20-40 particle diameters.Comparison of velocity profiles near the walls and at the center of the bed shows significant impact of the front and back walls on the flow hydrodynamics of pseudo-2D fluidized beds.Hence,for quantitative comparison with experiments in pseudo-2D columns,the effect of wails has to be accounted for in numerical simulations.

  9. CFD-DEM study of effect of bed thickness for bubbling fluidized beds

    Energy Technology Data Exchange (ETDEWEB)

    Tingwen, Li; Gopalakrishnan, Pradeep; Garg, Rahul; Shahnam, Mehrdad

    2011-10-01

    The effect of bed thickness in rectangular fluidized beds is investigated through the CFD–DEM simulations of small-scale systems. Numerical results are compared for bubbling fluidized beds of various bed thicknesses with respect to particle packing, bed expansion, bubble behavior, solids velocities, and particle kinetic energy. Good two-dimensional (2D) flow behavior is observed in the bed having a thickness of up to 20 particle diameters. However, a strong three-dimensional (3D) flow behavior is observed in beds with a thickness of 40 particle diameters, indicating the transition from 2D flow to 3D flow within the range of 20–40 particle diameters. Comparison of velocity profiles near the walls and at the center of the bed shows significant impact of the front and back walls on the flow hydrodynamics of pseudo-2D fluidized beds. Hence, for quantitative comparison with experiments in pseudo-2D columns, the effect of walls has to be accounted for in numerical simulations.

  10. HIGH FIELD Q-SLOPE AND THE BAKING EFFECT

    Energy Technology Data Exchange (ETDEWEB)

    Ciovati, Gianluigi [JLAB

    2009-11-01

    The performance of SRF cavities made of bulk Nb at high fields (peak surface magnetic field greater than about 90 mT) is characterized by exponentially increasing RF losses (high-field Q-slope), in the absence of field emission, which are often mitigated by a low temperature (100-140 °C, 12-48h) baking. In this contribution, recent experimental results and phenomenological models to explain this effect will be briefly reviewed. New experimental results on the high-field Q-slope will be presented for cavities that had been heat treated at high temperature in the presence of a small partial pressure of nitrogen. Improvement of the cavity performances have been obtained, while surface analysis measurements on Nb samples treated with the cavities revealed significantly lower hydrogen concentration than for samples that followed standard cavity treatments.

  11. Effects of Topographic Slopes on Hydrological Proecsses and Climate

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Based on previous research results on river re-distribution models, a modification on the effects of topographic slopes for a runoff parameterization was proposed and implemented to the NCAR's land sur face model (LSM). This modification has two aspects: firstly, the topographic slopes cause outflows from higher topography and inflows into the lower topography points; secondly, topographic slopes also cause decrease of infiltration at higher topography and increases of infiltration at lower topography. Then changes in infiltration result in changes in soil moisture, surface fluxes and then in surface temperature, and eventual ly in the upper atmosphere and the climate. This mechanism is very clearly demonstrated in the point bud gets analysis at the Andes Mountains vicinities. Analysis from a regional scale perspective in the Mackenzie GEWEX Study (MAGS) area, the focus of the ongoing Canadian GEWEX program, shows that the modi fied runoff parameterization does bring significant changes in the regional surface climate. More important ly, detailed analysis from a global perspective shows many encouraging improvements introduced by the modified LSM over the original model in simulating basic atmospheric climate properties such as thermodynamic features (temperature and humidity). All of these improvements in the atmospheric climate simulation illustrate that the inclusion of topographic effects in the LSM can force the AGCM to produce a more realistic model climate.

  12. Effect of slope angle of an artificial pool on distributions of turbulence

    Institute of Scientific and Technical Information of China (English)

    Atefeh Fazlollahi; Hossein Afzalimehr; Jueyi Sui

    2015-01-01

    abstract Experiments were carried out over a 2-dimentional pool with a constant length of 1.5 m and four different slopes. The distributions of velocity, Reynolds stress and turbulence intensities have been studied in this paper. Results show that as flow continues up the exit slope, the flow velocity increases near the channel bed and decreases near the water surface. The flow separation was not observed by ADV at the crest of the bed-form. In addition, the length of the separation zone increases with the increasing of entrance and exit slopes. The largest slope angle causes the maximum normalized shear stress. Based on the experiments, it is concluded that the shape of Reynolds stress distribution is generally dependent on the entrance and exit slopes of the pool. Also, the shape of Reynolds stress distribution is affected by both decelerating and accelerating flows. Additionally, with the increase in the slope angle, secondary currents are developed and become more stable. Results of the quadrant analysis show that the momentum between flow and bed-form is mostly transferred by sweep and ejection events.&2015 International Research and Training Centre on Erosion and Sedimentation/the World Association for Sedimentation and Erosion Research. Published by Elsevier B.V. All rights reserved.

  13. Effect of bed particles to combustion of gases in fluidized bed

    Energy Technology Data Exchange (ETDEWEB)

    Raiko, R.; Wallen, V.; Etelaeaho, R.; Correia, S. [Tampere Univ. of Technology (Finland). Energy and Process Engineering

    1997-10-01

    The objective of this project was to obtain experimental data on effects of sand particles to the combustion of gases. The effect of the surface area of the particles was tested using different sized particles. The fluidized bed reactor used in these experiments was a stainless-steel tube with an internal diameter of 42 mm surrounded by an electric heater. The test rig was built in the Laboratory of Energy and Process Engineering at Tampere University of Technology. In order to elucidate the possible changes of particle surface, microscopic and porosimetric studies were conducted with both fresh bed particles and used bed particles. These measurements indicate that carbon monoxide significantly reacts with oxygen in the particulate or emulsion phase of a fluidized bed, if the residence time is long enough. The reaction rate depends mainly on temperature, air coefficient, residence time and particle size of the solids. It seems that the combustion enhances if the average particle size increases. Whether this is caused by increased free path length or reduced specific surface area of the bed is yet unknown. The first might be more probable cause because the majority of reactions often took place in the freeboard right above the bed. It was clear that the bed hindered proper combustion in several cases. (orig.)

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

    Indian Academy of Sciences (India)

    Mohammad Hossein Omid; Masoud Karbasi; Javad Farhoudi

    2010-12-01

    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 250 mm wide and 12·5 m long with glass-sides of rectangular cross-section and artificial dune shaped floor that was made from Plexi-glass. Steady flow of clear as against sediment-laden water with different flow depths and velocities were studied in the experiments with a fine sand ($d_{50} =$ 0·5 mm). The results indicate that the transport of fine particles ($d_{50} =$ 0·5 mm) can decrease the friction factor by 22% and 24% respectively for smooth and rough beds. Increasing the bed-load size ($d_{50} =$ 2·84 mm) can decrease the friction factor by 32% and 39% respectively for smooth and rough beds. The decrease in flow resistance is due to filling up of the troughs of dunes. This separation zone is responsible for increasing the flow resistance. On the upstream side of dunes condition is similar to plane bed. Presence of bed-load causes to increase the shear velocity and hence increasing flow resistance. But decreasing in flow resistance is more and it causes to decrease the total flow resistance. Grains saturated the troughs in the bed topography, effectively helping in smoothening of bed irregularities.

  15. Effect of slope height and horizontal forces on the bearing capacity of strip footings near slopes in cohesionless soil

    DEFF Research Database (Denmark)

    Krabbenhøft, Sven; Damkilde, Lars; Krabbenhøft, Kristian

    2016-01-01

    , and in such cases the bearing capacity of the footing cannot be found using the existing methods. The present work comprises finite element based upper- and lower-bound calculations, using the geotechnical software OptumG2 to investigate the effect of the slope height and horizontal forces on the total bearing...

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

    Science.gov (United States)

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

    2012-02-01

    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 non-erodible bed conditions. Hence, this study aimed to examine the influence of unit discharge, mean flow velocity and slope gradient on sediment transport capacity for erodible beds and also to investigate the relationship between transport capacity and composite force predictors, i.e. shear stress, stream power, unit stream power and effective stream power. In order to accomplish the objectives, experiments were carried out in a 3.0 m long and 0.5 m wide flume using four well sorted sands (0.230, 0.536, 0.719, 1.022 mm). Unit discharges ranging from 0.07 to 2.07 × 10-3 m2 s-1 were simulated inside the flume at four slopes (5.2, 8.7, 13.2 and 17.6%) to analyze their impact on sediment transport rate. The sediment transport rate measured at the bottom end of the flume by taking water and sediment samples was considered equal to sediment transport capacity, because the selected flume length of 3.0 m was found sufficient to reach the transport capacity. The experimental result reveals that the slope gradient has a stronger impact on transport capacity than unit discharge and mean flow velocity due to the fact that the tangential component of gravity force increases with slope gradient. Our results show that unit stream power is an optimal composite force predictor for estimating transport capacity. Stream power and effective stream power can also be successfully related to the transport capacity, however the relations are strongly dependent on grain size. Shear stress showed poor performance, because part of shear stress is dissipated by bed irregularities, bed form evolution and sediment detachment. An empirical transport capacity equation was derived, which illustrates that

  17. Variance-in-Mean Effects of the Long Forward-Rate Slope

    DEFF Research Database (Denmark)

    Christiansen, Charlotte

    2005-01-01

    This paper contains an empirical analysis of the dependence of the long forward-rate slope on the long-rate variance. The long forward-rate slope and the long rate are described by a bivariate GARCH-in-mean model. In accordance with theory, a negative long-rate variance-in-mean effect for the long...... forward-rate slope is documented. Thus, the greater the long-rate variance, the steeper the long forward-rate curve slopes downward (the long forward-rate slope is negative). The variance-in-mean effect is both statistically and economically significant....

  18. Aspen shaving versus chip bedding: effects on breeding and behavior.

    Science.gov (United States)

    Jackson, E; Demarest, K; Eckert, W J; Cates-Gatto, C; Nadav, T; Cates, L N; Howard, H; Roberts, A J

    2015-01-01

    The choice of laboratory cage bedding material is often based on both practical and husbandry issues, whereas behavioral outcomes rarely appear to be considered. It has been noted that a breeding success difference appears to be associated with the differential use of aspen chip and aspen shaving bedding in our facility; therefore, we sought to analyze breeding records maintained over a 20-month period. In fact, in all four mouse strains analyzed, shaving bedding was associated with a significant increase in average weanlings per litter relative to chip bedding. To determine whether these bedding types also resulted in differences in behaviors associated with wellbeing, we examined nest building, anxiety-like, depressive-like (or helpless-like), and social behavior in mice housed on chip versus shaving bedding. We found differences in the nests built, but no overall effect of bedding type on the other behaviors examined. Therefore, we argue that breeding success, perhaps especially in more challenging strains, is improved on shaving bedding and this is likely due to improved nest-building potential. For standard laboratory practices, however, these bedding types appear equivalent.

  19. Stabilizing effect of plasma discharge on bubbling fluidized granular bed

    Science.gov (United States)

    Hu, Mao-Bin; Dang, Sai-Chao; Ma, Qiang; Xia, Wei-Dong

    2015-07-01

    Fluidized beds have been widely used for processing granular materials. In this paper, we study the effect of plasma on the fluidization behavior of a bubbling fluidized bed with an atmospheric pressure plasma discharger. Experiment results show that the bubbling fluidized bed is stabilized with the discharge of plasma. When the discharge current reaches a minimum stabilization current Cms, air bubbles in the bed will disappear and the surface fluctuation is completely suppressed. A simplified model is proposed to consider the effect of electric Coulomb force generated by the plasma. It is found that the Coulomb force will propel the particles to move towards the void area, so that the bubbling fluidized bed is stabilized with a high enough plasma discharge. Project supported by the National Natural Science Foundation of China (Grant Nos. 11035005 and 11034010).

  20. Effect of Different Groundwater Levels on Seismic Dynamic Response and Failure Mode of Sandy Slope.

    Science.gov (United States)

    Huang, Shuai; Lv, Yuejun; Peng, Yanju; Zhang, Lifang; Xiu, Liwei

    2015-01-01

    Heavy seismic damage tends to occur in slopes when groundwater is present. The main objectives of this paper are to determine the dynamic response and failure mode of sandy slope subjected simultaneously to seismic forces and variable groundwater conditions. This paper applies the finite element method, which is a fast and efficient design tool in modern engineering analysis, to evaluate dynamic response of the slope subjected simultaneously to seismic forces and variable groundwater conditions. Shaking table test is conducted to analyze the failure mode and verify the accuracy of the finite element method results. The research results show that dynamic response values of the slope have different variation rules under near and far field earthquakes. And the damage location and pattern of the slope are different in varying groundwater conditions. The destruction starts at the top of the slope when the slope is in no groundwater, which shows that the slope appears obvious whipping effect under the earthquake. The destruction starts at the toe of the slope when the slope is in the high groundwater levels. Meanwhile, the top of the slope shows obvious seismic subsidence phenomenon after earthquake. Furthermore, the existence of the groundwater has a certain effect of damping.

  1. Effect of Different Groundwater Levels on Seismic Dynamic Response and Failure Mode of Sandy Slope.

    Directory of Open Access Journals (Sweden)

    Shuai Huang

    Full Text Available Heavy seismic damage tends to occur in slopes when groundwater is present. The main objectives of this paper are to determine the dynamic response and failure mode of sandy slope subjected simultaneously to seismic forces and variable groundwater conditions. This paper applies the finite element method, which is a fast and efficient design tool in modern engineering analysis, to evaluate dynamic response of the slope subjected simultaneously to seismic forces and variable groundwater conditions. Shaking table test is conducted to analyze the failure mode and verify the accuracy of the finite element method results. The research results show that dynamic response values of the slope have different variation rules under near and far field earthquakes. And the damage location and pattern of the slope are different in varying groundwater conditions. The destruction starts at the top of the slope when the slope is in no groundwater, which shows that the slope appears obvious whipping effect under the earthquake. The destruction starts at the toe of the slope when the slope is in the high groundwater levels. Meanwhile, the top of the slope shows obvious seismic subsidence phenomenon after earthquake. Furthermore, the existence of the groundwater has a certain effect of damping.

  2. Bed of polydisperse viscous spherical drops under thermocapillary effects

    Science.gov (United States)

    Sharanya, V.; Raja Sekhar, G. P.; Rohde, Christian

    2016-08-01

    Viscous flow past an ensemble of polydisperse spherical drops is investigated under thermocapillary effects. We assume that the collection of spherical drops behaves as a porous media and estimates the hydrodynamic interactions analytically via the so- called cell model that is defined around a specific representative particle. In this method, the hydrodynamic interactions are assumed to be accounted by suitable boundary conditions on a fictitious fluid envelope surrounding the representative particle. The force calculated on this representative particle will then be extended to a bed of spherical drops visualized as a Darcy porous bed. Thus, the "effective bed permeability" of such a porous bed will be computed as a function of various parameters and then will be compared with Carman-Kozeny relation. We use cell model approach to a packed bed of spherical drops of uniform size (monodisperse spherical drops) and then extend the work for a packed bed of polydisperse spherical drops, for a specific parameters. Our results show a good agreement with the Carman-Kozeny relation for the case of monodisperse spherical drops. The prediction of overall bed permeability using our present model agrees well with the Carman-Kozeny relation when the packing size distribution is narrow, whereas a small deviation can be noted when the size distribution becomes broader.

  3. Analysis of effective solid stresses in a conical spouted bed

    Directory of Open Access Journals (Sweden)

    CHARBEL A. L. T.

    1999-01-01

    Full Text Available Some applications of spouted beds have been limited by problems with spout stability. In order to overcome these limitations, research should be concentrated on describing the mechanism by which the spout is developed. This work presents a theoretical and experimental study to describe the effective solid stress distribution in the annular region of a conical spouted bed. From experimental observation, the failure state of the bed of particles at the outset of spouting is identified and related to fluid-particle properties and column dimensions. Linear and angular momentum balances for the solid phase are then formulated as a function of the bed failure state. The set of equations obtained is solved using numerical methods, and results regarding stress distribution, stability and spout shape are presented and discussed.

  4. Effects of gasifying conditions and bed materials on fluidized bed steam gasification of wood biomass.

    Science.gov (United States)

    Weerachanchai, Piyarat; Horio, Masayuki; Tangsathitkulchai, Chaiyot

    2009-02-01

    The effect of steam gasification conditions on products properties was investigated in a bubbling fluidized bed reactor, using larch wood as the starting material. For bed material effect, calcined limestone and calcined waste concrete gave high content of H(2) and CO(2), while silica sand provided the high content of CO. At 650 degrees C, calcined limestone proved to be most effective for tar adsorption and showed high ability to adsorb CO(2) in bed. At 750 degrees C it could not capture CO(2) but still gave the highest cold gas efficiency (% LHV) of 79.61%. Steam gasification gave higher amount of gas product and higher H(2)/CO ratio than those obtained with N(2) pyrolysis. The combined use of calcined limestone and calcined waste concrete with equal proportion contributed relatively the same gas composition, gas yield and cold gas efficiency as those of calcined limestone, but showed less attrition, sintering, and agglomeration propensities similar to the use of calcined waste concrete alone.

  5. Meteorological, elevation, and slope effects on surface hoar formation

    Science.gov (United States)

    Horton, S.; Schirmer, M.; Jamieson, B.

    2015-08-01

    Failure in layers of buried surface hoar crystals (frost) can cause hazardous snow slab avalanches. Surface hoar crystals form on the snow surface and are sensitive to micro-meteorological conditions. In this study, the role of meteorological and terrain factors was investigated for three layers of surface hoar in the Columbia Mountains of Canada. The distribution of crystals over different elevations and aspects was observed on 20 days of field observations during a period of high pressure. The same layers were modelled over simplified terrain on a 2.5 km horizontal grid by forcing the snow cover model SNOWPACK with forecast weather data from a numerical weather prediction model. Modelled surface hoar growth was associated with warm air temperatures, high humidity, cold surface temperatures, and low wind speeds. Surface hoar was most developed in regions and elevation bands where these conditions existed, although strong winds at high elevations caused some model discrepancies. SNOWPACK simulations on virtual slopes systematically predicted smaller surface hoar on south-facing slopes. In the field, a complex combination of surface hoar and sun crusts were observed, suggesting the simplified model did not adequately resolve the surface energy balance on slopes. Overall, a coupled weather-snow cover model could benefit avalanche forecasters by predicting surface hoar layers on a regional scale over different elevation bands.

  6. Short-term vegetation recovery after a spring grassland fire in Lithuania. Effect of time and slope position

    Directory of Open Access Journals (Sweden)

    P. Pereira

    2013-01-01

    Full Text Available The aim of this work is study the effects of a grassland fire in vegetation recuperation according to fire severity, slope exposition and position. We designed two experimental plots, one located in an east faced slope (Slope A and other in a west faced (Slope B. Vegetation recuperation was assessed 10, 17, 31 and 46 days after the fire. The results showed that fire severity was higher in slope B, than in slope A. In both slopes vegetation recuperation was different according position. Bottom positions recovered faster than slope and upslope positions, that it is attributed to fire severity (higher in slope and upslope areas and ash and soil transport and deposition in bottom areas. The vegetation recuperated faster in slope B and 46 days after the fire, 100% of the plot was covered. This was attributed to higher severity, more complex topography, and inclination of Slope A, that delayed the vegetation recover.

  7. Effects of rye grass coverage on soil loss from loess slopes

    Directory of Open Access Journals (Sweden)

    Yuequn Dong

    2015-09-01

    Full Text Available Vegetative coverage is commonly used to reduce urban slope soil erosion. Laboratory experimental study on soil erosion under grass covered slopes is conventionally time and space consuming. In this study, a new method is suggested to study the influences of vegetation coverage on soil erosion from a sloped loess surface under three slope gradients of 5°, 15°, and 25°; four rye grass coverages of 0%, 25%, 50%, and 75%; and three rainfall intensities of 60, 90, and 120 mm/h with a silt-loamy loess soil. Rye grasses were planted in the field with the studied soil before being transplanted into a laboratory flume. Grass was allowed to resume growth for a period before the rain simulation experiment. Results showed that the grass cover reduced soil erosion by 63.90% to 92.75% and sediment transport rate by 80.59% to 96.17% under different slope gradients and rainfall intensities. The sediment concentration/sediment transport rate from bare slope was significantly higher than from a grass-covered slope. The sediment concentration/transport rate from grass-covered slopes decreased linearly with grass coverage and increased with rainfall intensity. The sediment concentration/transport rate from the bare slope increased as a power function of slope and reached the maximum value at the gradient of about 25°, whereas that from grass-covered slope increased linearly and at much lower levels. The results of this study can be used to estimate the effect of vegetation on soil erosion from loess slopes.

  8. Effect of prolonged bed rest on the anterior hip muscles.

    Science.gov (United States)

    Dilani Mendis, M; Hides, Julie A; Wilson, Stephen J; Grimaldi, Alison; Belavý, Daniel L; Stanton, Warren; Felsenberg, Dieter; Rittweger, Joern; Richardson, Carolyn

    2009-11-01

    Prolonged bed rest and inactivity is known to cause muscular atrophy with previous research indicating that muscles involved in joint stabilisation are more susceptible. The anterior hip muscles are important for hip joint function and stability but little is known about the effects of prolonged inactivity on their function. This study investigated the effect of prolonged bed rest on the size of the anterior hip muscles and their pattern of recovery. The effect of resistive vibration exercise (RVE) as a countermeasure to muscle atrophy was also investigated. 12 male participants, randomly assigned to either a control or an exercise group, underwent 8 weeks of bed rest with 6 months follow-up. Changes in muscle cross-sectional area (CSA) of the iliacus, psoas, iliopsoas, sartorius and rectus femoris muscles were measured by magnetic resonance imaging at regular intervals during bed rest and recovery phases. CSAs of iliopsoas and sartorius decreased at the hip joint (piliacus, psoas, and rectus femoris CSAs were unchanged (p>0.05). No significant difference was found between the two groups for all muscles (all p>0.1), suggesting inefficacy of the countermeasure in this sample. These findings suggest that prolonged bed rest can result in the atrophy of specific muscles across the hip joint which may affect its stability and function.

  9. Effect of slope height and horizontal forces on the bearing capacity of strip footings near slopes in cohesionless soil

    DEFF Research Database (Denmark)

    Krabbenhøft, Sven; Damkilde, Lars; Krabbenhøft, Kristian

    2016-01-01

    The problem of determining the bearing capacity of a strip foundation located near a slope of infinite height has been dealt with by several authors. Very often in practical problems the slope is of limited height, and furthermore the resulting load may be inclined at an angle to the horizontal, ...

  10. Buoyancy Effect on MHD Flow Past a Permeable Bed

    Directory of Open Access Journals (Sweden)

    S. Venkataramana

    1986-10-01

    Full Text Available In this paper, the effect of buoyancy force on the parallel flows bounded above by a rigid permeable plate which may be moving or stationary and below, by a permeable bed has been investigated. To discuss the solution, the flow region is divided into two zones. In Zone 1, the flow is laminar and is governed by the Navier-Stokes equations from the impermeable upper rigid plate to the permeable bed. In Zone 2, the flow is governed by the Darcy law in the permeable bed below the nominal surface. The expressions for velocity and temparature distributions, Slip velocity, slip temperature, mass flow rate and the rates of heat transfer coefficients are obtained. The effects of magnetic, porous, slip and buoyancy parameters and Biot number on the above physical quantities are investigated. The thickness of the boundary layer in Zone 2 has been evaluated.

  11. The Effect of Rainfall Patterns on the Mechanisms of Shallow Slope Failure

    Directory of Open Access Journals (Sweden)

    Muhammad Suradi

    2014-04-01

    Full Text Available This paper examines how rainfall patterns affect the mechanisms of shallow slope failure. Numerical modelling, utilising the commercial software SVFlux and SVSlope, was carried out for a coupled analysis of rainfall-induced slope seepage and instability, with reference to a shallow landslide took place in Jabiru, Northern Territory (NT Australia in 2007. Rainfall events were varied in terms of pattern in this analysis. The results revealed that slopes are sensitive to rainfall pattern when the rainfall intensity has a high degree of fluctuation at around the same value as that of saturated hydraulic conductivity. Average rainfall intensity at the beginning of a rainfall period plays a primary role in determining the rate of decrease in initial factor of safety (Fi towards minimum factor of safety (Fmin. The effect of rainfall events on the slope instability is attributed to the amount of rainwater infiltration into slope associated with rainfall pattern.

  12. Stability analysis of sandy slope considering anisotropy effect in friction angle

    Indian Academy of Sciences (India)

    Hamed Farshbaf Aghajani; Hossein Salehzadeh; Habib Shahnazari

    2015-09-01

    This paper aims to investigate the effect of anisotropy of shear strength parameter on the stability of a sandy slope by performing the limit equilibrium analysis. Because of scarcity of mathematical equation for anisotropic friction angle of sand, at first, all results of principal stress rotation tests are processed by artificial neural network and a computational procedure is developed for determining sand friction angle subjected to various loading directions. By implementing this procedure, slope stability analysis is performed in both isotropic and anisotropic conditions. The results indicate that while isotropic slope stability overestimates the factor of safety between 5 and 25% which the deviation is more for flatter slope, the location of critical slip surface is coincident in both conditions. Also in specific slip surface, the parameters of face angle, geometry of slip surface and soil properties relating to anisotropy are the main factors governing the result of anisotropic slope stability.

  13. A laboratory investigation into the effects of slope on lava flow morphology

    Science.gov (United States)

    Gregg, Tracy K. P.; Fink, Jonathan H.

    2000-03-01

    In an attempt to model the effect of slope on the dynamics of lava flow emplacement, four distinct morphologies were repeatedly produced in a series of laboratory simulations where polyethylene glycol (PEG) was extruded at a constant rate beneath cold sucrose solution onto a uniform slope which could be varied from 1° through 60°. The lowest extrusion rates and slopes, and highest cooling rates, produced flows that rapidly crusted over and advanced through bulbous toes, or pillows (similar to subaerial "toey" pahoehoe flows and to submarine pillowed flows). As extrusion rate and slope increased, and cooling rate decreased, pillowed flows gave way to rifted flows (linear zones of liquid wax separated by plates of solid crust, similar to what is observed on the surface of convecting lava lakes), then to folded flows with surface crusts buckled transversely to the flow direction, and, at the highest extrusion rates and slopes, and lowest cooling rates, to leveed flows, which solidified only at their margins. A dimensionless parameter, Ψ, primarily controlled by effusion rate, cooling rate and flow viscosity, quantifies these flow types. Increasing the underlying slope up to 30° allows the liquid wax to advance further before solidifying, with an effect similar to that of increasing the effusion rate. For example, conditions that produce rifted flows on a 10° slope result in folded flows on a 30° slope. For underlying slopes of 40°, however, this trend reverses, slightly owing to increased gravitational forces relative to the strength of the solid wax. Because of its significant influence on heat advection and the disruption of a solid crust, slope must be incorporated into any quantitative attempt to correlate eruption parameters and lava flow morphologies. These experiments and subsequent scaling incorporate key physical parameters of both an extrusion and its environment, allowing their results to be used to interpret lava flow morphologies on land, on the

  14. The effect of shearing rate and slope angle on the simple shear response of marine clays

    Science.gov (United States)

    Biscontin, G.; Rutherford, C.

    2010-12-01

    The response of submarine slopes to seismic or storm loading has become an important element in the risk assessment for offshore structures and local tsunami hazard. Evaluation of submarine slope stability requires characterization of soil behavior and relies on the selection of appropriate parameter values. Although the traditional simple shear device has been used to investigate cyclic loading effects on marine clay, it does not allow for complex loading conditions which often contribute to the failure on submarine slopes. Understanding the interaction between the initial shear stress, the slope angle, and the multi-directional shaking due to earthquakes or storm loading is an important aspect to understanding the failure mechanisms of submarine slope failures. The initial static driving force on the slope is combined with the dynamic loading by storms and earthquakes to create complex loading paths. Therefore, the ability to apply complex stress or strain paths is important to fully study the shear response of marine clays on submarine slopes. A new multi-directional simple shear device developed at Texas A&M University allows loading along three independent axes, two perpendicular horizontal directions to allow any stress or strain paths in the horizontal plane, and a third in the vertical direction. This device is used to investigate the response of Gulf of Mexico marine deposits to different loading conditions. To study the effect of slope angle on the shear response of the soil, samples are subjected to a shear stress during consolidation, Kα consolidation. One-dimensional monotonic and cyclic shearing of Ko consolidated specimens is used to simulate level ground conditions, whereas sloping surfaces were simulated using Kα consolidation for both monotonic and cyclic tests. The effects of shearing rate on the soil response are investigated using strain controlled tests at varying frequencies.

  15. Effect of slope position on physico-chemical properties of eroded soil

    Directory of Open Access Journals (Sweden)

    Farmanullah Khan, Zubair Hayat, Waqar Ahmad,

    2013-05-01

    Full Text Available The research work was conducted on eroded soil (Missa Series in Samarbagh, District Lower Dir to determine the effect of slope position on soil physico-chemical properties. Soil samples were collected from top-slope, mid-slope and bottom slope positions at horizon-A, B and C. Results showed a significant difference among the physico-chemical properties of top, mid and bottom slope soils. Bulk density of the top-slope (1.51 g cm-3 was the highest followed by mid (1.39 g cm-3 and bottom slopes (1.32 g cm-3. Conversely, electrical conductivity EC-2.47 dS m-1, phosphorus (3.40 mg kg-1, Potassium (118.8 mg kg-1, Organic matter content (1.52 %, clay content (20.39 % and silt content (49.17% were the highest at bottom slope followed by mid and top-slopes, respectively. Soil A, B and C horizons were also significantly (p<0.05 different in their physico-chemical properties. Mean values showed that horizon Ap had the highest bulk density (1.43 g cm-3 and lower electrical conductivity (1.74 dS m-1, phosphorus (2.29 mg kg-1, potassium (84.86 mg kg-1, organic matter (1.08%, clay (12.83% and silt content (40.49% than both the B and C horizons. The deterioration in physico-chemical properties of top slope as compared to mid and bottom slopes and that of Ap horizon as compared to B and C horizons were presumed to be due to past soil erosion effect that removed the finer soil particles including soil organic matter and other plant nutrients. This study concluded that increasing extent of erosion due to slope effect can further deteriorate soil properties. The control of such damaging effects would require soil conservation strategies such as proper land levelling, afforestation, terracing and inclusion of restorative crops in cropping systems on these lands.

  16. The effect of slope angle on splash detachment in steep forest plantation

    Science.gov (United States)

    Mizugaki, S.; Nanko, K.; Onda, Y.

    2007-12-01

    To study splash detachment rate and investigate the effects of rainfall and slope angle on splash detachment, the field observation of splash detachment was conducted for five months using 27 splash cups under natural rainfall events in Japanese cypress (Hinoki; Chamaecyparis obtusa) plantation in the Shimanto River watershed, southern Japan. In this plantation forest, the unit kinetic energy of throughfall (unit KE; J/m2/mm) was found to be constant independent of rainfall intensity. The total rainfall over six observation periods was 853 mm and the maximum rainfall intensity for 1 h ( RI1h) varied from 8.0 to 19.6 mm h-1. A significantly high coefficient of linear regression was found between RI1h and the average splash detachment of all splash cups over six periods, although the splash detachment from the individual cups had larger variations with RI1h. This variation in splash detachment may attribute to the spatial variability in soil surface condition such as slope angle. In the relationship between the splash detachment and slope angle, no correlation was found over the entire periods. However, different correlations were found among the observation periods due to the differences in rainfall intensity. The splash detachment from a lower slope angle (14°) exhibited a strong relation with the maximum rainfall intensity for a shorter period, such as 10 to 30 minutes. In contrast, the splash detachment from a slope angle of over 35° exhibited high correlation with the maximum rainfall intensity for 3 h, suggesting that longer time is required for ponding in steeper slopes than gentler slopes. In gentler slopes, prolonged rainfall may cause the higher ponding depth, resulting in reducing the raindrop impact and less splash detachment. Therefore, under the forest canopies, the effect of slope angle on the rainfall parameter should be incorporated into the future splash erosion model.

  17. The Effect of Rotation Period on Slope Distribution on Asteroid Itokawa

    Science.gov (United States)

    Kanamaru, Masanori; Sasaki, Sho

    2016-07-01

    The centrifugal force due to the rotation occupies a big part of the surface gravity field for small solar system bodies, for example, Asteroid 25143 Itokawa. Change of rotation period by solar radiation is known as YORP effect. This phenomenon makes a strong effect on Itokawa's history of reconfiguration and surface terrain formation in hundreds of thousand years time span. We calculated the gravity potential, acceleration and slope over the Itokawa surface by means of a calculation method for a polyhedron with a homogeneous density (Werner and Scheeres (1997)). "Slope" is defined as the separation angle of a gravity acceleration vector and a normal vector of a surface facet. In this study, we used Itokawa shape models (Gaskell et al. 2006) and the bulk density value 1.95 grams per cubic centimeters (Abe et al. 2006). We investigated slope distributions with different rotation period (4h, 6.5h, 9h, 12.1324h, 18h, 24h). In addition, we made a slope histogram only for the neck region (150 < x < 250) of Itokawa in order to investigate a difference of slope distribution between all over the body and in a specific region. We found that the number of steep slope facets decreased when we shortened the rotation period. Steep slope areas were fewest when we assumed the rotation period 6.5h. But, the surface became much steeper when we assumed the rotation period 4h. Slope distribution also depended on regions. Steep slope areas were concentrated on the neck region. The slope histogram all over the body had a peak around 10 degrees, while the histogram only for the neck region had a peak around 20 degrees and there existed more steeper areas than that. Such a steep slope seems to be unstable. If a slope angle is an indicator of mismatch between a gravity field and local topography, we can reduce that by accelerating the rotation rate. One of possible scenarios for Itokawa formation is that Itokawa rotated much faster before and surface topography was formed according to the

  18. The effects of sufentanil in the feline pulmonary vascular bed.

    Science.gov (United States)

    Kaye, Alan D; Phelps, James; Baluch, Amir; Ibrahim, Ikhlass N; Hoover, Jason M; Baber, Syed R; Zhang, Cuihua; Armstrong, Christopher; Huffman, Shane; Fields, Aaron

    2006-03-18

    The purpose of this prospective vehicle controlled study was to test the hypothesis that sufentanil induces a depressor response in the pulmonary vascular bed of the cat and identify the receptors involved in the mediation or modulation of these effects. In separate experiments, the effects of diphenydramine (histamine receptor blocker), glibenclamide (ATP-sensitive K+ channel blocker), L-N5-(1-Iminoethyl) ornithine hydrochloride (L-NIO) (nitric oxide synthase inhibitor), nimesulide (selective cyclooxygenase (COX)-2 inhibitor), and naloxone (opiate receptor antagonist) were investigated on pulmonary arterial responses to sufentanil and other agonists in the feline pulmonary vascular bed. The lobar arterial perfusion pressures were continuously monitored, electronically averaged, and recorded. In the feline pulmonary vascular bed of the isolated left lower lobe, sufentanil induced a dose-dependent vasodepressor response that was not significantly altered after administration of glibenclamide, L-NIO, and nimesulide. However, the responses to sufentanil were significantly attenuated following administration of diphenhydramine and naloxone. The results of the present study suggest that sufentanil has potent vasodepressor activity in the pulmonary vascular bed of the cat and that this response may be mediated or modulated by both histaminergic and opioid receptor sensitive pathways.

  19. Comparison of the Effects of the Different Methods for Computing the Slope Length Factor at a Watershed Scale

    Directory of Open Access Journals (Sweden)

    Fu Suhua

    2013-09-01

    Full Text Available The slope length factor is one of the parameters of the Universal Soil Loss Equation (USLE and the Revised Universal Soil Loss Equation (RUSLE and is sometimes calculated based on a digital elevation model (DEM. The methods for calculating the slope length factor are important because the values obtained may depend on the methods used for calculation. The purpose of this study was to compare the difference in spatial distribution of the slope length factor between the different methods at a watershed scale. One method used the uniform slope length factor equation (USLFE where the effects of slope irregularities (such as slope gradient, etc. on soil erosion by water were not considered. The other method used segmented slope length factor equation(SSLFE which considered the effects of slope irregularities on soil erosion by water. The Arc Macro Language (AML Version 4 program for the revised universal soil loss equation(RUSLE.which uses the USLFE, was chosen to calculate the slope length factor. In a parallel analysis, the AML code of RUSLE Version 4 was modified according to the SSLFE to calculate the slope length factor. Two watersheds with different slope and gully densities were chosen. The results show that the slope length factor and soil loss using the USLFE method were lower than those using the SSLFE method, especially on downslopes watershed with more frequent steep slopes and higher gully densities. In addition, the slope length factor and soil loss calculated by the USLFE showed less spatial variation.

  20. [Effects of land use type and slope position on soil physical properties in loess tableland area].

    Science.gov (United States)

    Li, Zhi; Liu, Wen-Zhao; Wang, Qiu-Xian

    2008-06-01

    Soil samples under different land use types and at different slope positions in the Wangdonggou watershed of loess tableland area were collected to determine their particle composition, bulk density (pb), and saturated hydraulic conductivity (Ks), and the effects of land use type and slope position on the soil physical properties were studied in virtue of the variation coefficient and non-parameter tests. The results showed that the physical properties of soil varied in horizontal direction and vertical profile, however at the same slope position or under the same land use type, the pb and particle composition were similar. In horizontal direction, Ks varied strongly, slit content and pb varied weakly, and clay and sand contents varied medially. In vertical profile, soil particles had a continuous distribution, but pb and Ks varied greatly in 0-25 cm layer. With the slope degree descended, soil contained more clay and had a higher pb, and Ks increased. At upper and middle slopes, soil physical properties were similar, and thus, could be merged into one in related researches. There was a significant difference in soil physical properties between grassland and other land use types, which was mainly due to the effects of slope position, but the soil physical properties in farmland and orchard were similar, indicating the important effects of human activities.

  1. Quantifying Slope Effects and Variations in Crater Density across a Single Geologic Unit

    Science.gov (United States)

    Meyer, Heather; Mahanti, Prasun; Robinson, Mark; Povilaitis, Reinhold

    2016-10-01

    Steep underlying slopes (>~5°) significantly increase the rate of degradation of craters [1-3]. As a result, the density of craters is less on steeper slopes for terrains of the same age [2, 4]. Thus, when age-dating a planetary surface, an area encompassing one geologic unit of constant low slope is chosen. However, many key geologic units, such as ejecta blankets, lack sufficient area of constant slope to derive robust age estimates. Therefore, accurate age-dating of such units requires an accurate understanding of the effects of slope on age estimates. This work seeks to determine if the observed trend of decreasing crater density with increasing slopes [2] holds for craters >1 km and to quantify the effect of slope for craters of this size, focusing on the effect of slopes over the kilometer scale. Our study focuses on the continuous ejecta of Orientale basin, where we measure craters >1 km excluding secondaries that occur as chains or clusters. Age-dating via crater density measurements relies on uniform cratering across a single geologic unit. In the case of ejecta blankets and other impact related surfaces, this assumption may not hold due to the formation of auto- secondary craters. As such, we use LRO WAC mosaics [5], crater size-frequency distributions, absolute age estimates, a 3 km slope map derived from the WAC GLD100 [6], and density maps for various crater size ranges to look for evidence of non-uniform cratering across the continuous ejecta of Orientale and to determine the effect of slope on crater density. Preliminary results suggest that crater density does decrease with increasing slope for craters >1 km in diameter though at a slower rate than for smaller craters.References: [1] Trask N. J. and Rowan L. C. (1967) Science 158, 1529-1535. [2] Basilevsky (1976) Proc. Lunar Sci. Conf. 7th, p. 1005-1020. [3] Pohn and Offield (1970) USGS Prof. Pap., 153-162. [4] Xiao et al. (2013) Earth and Planet. Sci. Lett., 376, pgs. 1-11. doi:10.1016/j.epsl.2013

  2. Dynamic Response and Dynamic Failure Mode of a Weak Intercalated Rock Slope Using a Shaking Table

    Science.gov (United States)

    Fan, Gang; Zhang, Jianjing; Wu, Jinbiao; Yan, Kongming

    2016-08-01

    A large-scale shaking table test was performed to study the dynamic response of slopes parallel to geological bedding (bedding slopes) and slopes that cross-cut geological bedding (counter-bedding slopes). The test results show that the acceleration amplification coefficients increase with increasing elevation and, when the input earthquake amplitude is greater than 0.3 g, both bedding and counter-bedding slopes begin to show nonlinear dynamic response characteristics. With increasing elevation, the displacement of the bedding slope surface increases greatly. Conversely, the displacement of the counter-bedding slope surface increases first and then decreases; the slope develops a bulge at the relative elevation of 0.85. The displacement of the bedding slope surface is greater than that of the counter-bedding slope. The counter-bedding slope is more seismically stable compared with the bedding slope. Based on the Hilbert-Huang transform and marginal spectrum theories, the processes that develop dynamic damage of the bedding and counter-bedding slopes are identified. It is shown that the dynamic failure mode of the bedding slope is mainly represented by vertical tensile cracks at the rear of the slope, bedding slide of the strata along the weak intercalation, and rock collapse from the slope crest. However, the dynamic failure mode of the counter-bedding slope is mainly represented by staggered horizontal and vertical fissures, extrusion of the weak intercalation, and breakage at the slope crest.

  3. Effects of shear elasticity on sea bed scattering: numerical examples.

    Science.gov (United States)

    Ivakin, A N; Jackson, D R

    1998-01-01

    It is known that marine sediments can support both compressional and shear waves. However, published work on scattering from irregular elastic media has not examined the influence of shear on sea bed scattering in detail. A perturbation model previously developed by the authors for joint roughness-volume scattering is used to study the effects of elasticity for three sea bed types: sedimentary rock, sand with high shear speed, and sand with "normal" shear wave speed. Both bistatic and monostatic cases are considered. For sedimentary rock it is found that shear elasticity tends to increase the importance of volume scattering and decrease the importance of roughness scattering relative to the fluid case. Shear effects are shown to be small for sands.

  4. Effect of pressure on combustion of char in fluidised beds

    Energy Technology Data Exchange (ETDEWEB)

    Turnbull, E.; Blackshaw, H.W.; Davidson, J.F.; Goodyer, P.T.Y.; Hopes, R.B.; Kossakowski, E.R.

    1984-07-01

    Measurements of burn-out time are reported, for 0.25-1.7 mm carbon particles in an air-fluidised 100 mm dia bed of sand at pressures up to 17 bar absolute and bed temperatures of 1023-1173 K. A variety of carbons was used including (i) coke (ii) chars formed from coals of different ranks: thus the carbons had various porosities and surface areas. The effect of increased pressure is to increase the combustion rate, because of the higher oxygen concentration which accelerates the chemical reactions of combustion. On the other hand, pressure has virtually no influence on diffusion of oxygen towards a burning particle, because the higher oxygen concentration is offset by a proportionately lower diffusion coefficient. The overall effect is that as pressure increases, the chemical rate controlling steps become less important, so at very high pressure, combustion is diffusion controlled.

  5. Rheological Characteristics of Weak Rock Mass and Effects on the Long-Term Stability of Slopes

    Science.gov (United States)

    Yang, Tianhong; Xu, Tao; Liu, Hongyuan; Zhang, Chunming; Wang, Shanyong; Rui, Yongqin; Shen, Li

    2014-11-01

    The creep deformation behavior of the northern slope of an open-pit mine is introduced. Direct shear creep tests are then conducted for the samples taken from the northern slope to study the rheological characteristics of the rock mass. The experimental results are analyzed afterwards using an empirical method to develop a rheological model for the rock mass. The proposed rheological model is finally applied to understand the creep behavior of the northern slope, predict the long-term stability, and guide appropriate measures to be taken at suitable times to increase the factor of safety to ensure stability. Through this study, a failure criterion is proposed to predict the long-term stability of the slope based on the rheological characteristics of the rock mass and a critical deformation rate is adopted to determine when appropriate measures should be taken to ensure slope stability. The method has been successfully applied for stability analysis and engineering management of the toppling and slippage of the northern slope of the open-pit mine. This success in application indicates that it is theoretically accurate, practically feasible, and highly cost-effective.

  6. Effects of nonlinear strength parameters on stability of 3D soil slopes

    Institute of Scientific and Technical Information of China (English)

    高玉峰; 吴迪; 张飞; 秦红玉; 朱德胜

    2016-01-01

    Actual slope stability problems have three-dimensional (3D) characteristics and the soils of slopes have curved failure envelopes. This incorporates a power-law nonlinear failure criterion into the kinematic approach of limit analysis to conduct the evaluation of the stability of 3D slopes. A tangential technique is adopted to simplify the nonlinear failure criterion in the form of equivalent Mohr-Coulomb strength parameters. A class of 3D admissible rotational failure mechanisms is selected for soil slopes including three types of failure mechanisms: face failure, base failure, and toe failure. The upper-bound solutions and corresponding critical slip surfaces can be obtained by an efficient optimization method. The results indicate that the nonlinear parameters have significant influences on the assessment of slope stability, especially on the type of failure mechanism. The effects of nonlinear parameters appear to be pronounced for gentle slopes constrained to a narrow width. Compared with the solutions derived from plane-strain analysis, the 3D solutions are more sensitive to the values of nonlinear parameters.

  7. The effects of China’s Sloping Land Conversion Program on agricultural households

    DEFF Research Database (Denmark)

    Liu, Zhen; Henningsen, Arne

    In the late 1990s, China aimed to mitigate environmental degradation from agricultural production activities by introducing the world’s largest ’Payments for Environmental Services’ (PES) program ― the Sloping Land Conversion Program (SLCP). In order to analyze its effects on agricultural...... compensation payment rates has had some notable, but generally small effects....

  8. Numerical Simulations of the Effects of a Tidal Turbine Array on Near-Bed Velocity and Local Bed Shear Stress

    Directory of Open Access Journals (Sweden)

    Philip A. Gillibrand

    2016-10-01

    Full Text Available We apply a three-dimensional hydrodynamic model to consider the potential effects of energy extraction by an array of tidal turbines on the ambient near-bed velocity field and local bed shear stress in a coastal channel with strong tidal currents. Local bed shear stress plays a key role in local sediment dynamics. The model solves the Reynold-averaged Navier-Stokes (RANS equations on an unstructured mesh using mixed finite element and finite volume techniques. Tidal turbines are represented through an additional form drag in the momentum balance equation, with the thrust imparted and power generated by the turbines being velocity dependent with appropriate cut-in and cut-out velocities. Arrays of 1, 4 and 57 tidal turbines, each of 1.5 MW capacity, were simulated. Effects due to a single turbine and an array of four turbines were negligible. The main effect of the array of 57 turbines was to cause a shift in position of the jet through the tidal channel, as the flow was diverted around the tidal array. The net effect of this shift was to increase near-bed velocities and bed shear stress along the northern perimeter of the array by up to 0.8 m·s−1 and 5 Pa respectively. Within the array and directly downstream, near-bed velocities and bed shear stress were reduced by similar amounts. Changes of this magnitude have the potential to modify the known sand and shell banks in the region. Continued monitoring of the sediment distributions in the region will provide a valuable dataset on the impacts of tidal energy extraction on local sediment dynamics. Finally, the mean power generated per turbine is shown to decrease as the turbine array increased in size.

  9. Deleterious Thermal Effects Due To Randomized Flow Paths in Pebble Bed, and Particle Bed Style Reactors

    Science.gov (United States)

    Moran, Robert P.

    2013-01-01

    A review of literature associated with Pebble Bed and Particle Bed reactor core research has revealed a systemic problem inherent to reactor core concepts which utilize randomized rather than structured coolant channel flow paths. For both the Pebble Bed and Particle Bed Reactor designs; case studies reveal that for indeterminate reasons, regions within the core would suffer from excessive heating leading to thermal runaway and localized fuel melting. A thermal Computational Fluid Dynamics model was utilized to verify that In both the Pebble Bed and Particle Bed Reactor concepts randomized coolant channel pathways combined with localized high temperature regions would work together to resist the flow of coolant diverting it away from where it is needed the most to cooler less resistive pathways where it is needed the least. In other words given the choice via randomized coolant pathways the reactor coolant will take the path of least resistance, and hot zones offer the highest resistance. Having identified the relationship between randomized coolant channel pathways and localized fuel melting it is now safe to assume that other reactor concepts that utilize randomized coolant pathways such as the foam core reactor are also susceptible to this phenomenon.

  10. EFFECT OF VERTICAL BAFFLES ON PARTICLE MIXING AND DRYING IN FLUIDIZED BEDS OF GROUP D PARTICLES

    Institute of Scientific and Technical Information of China (English)

    Chung Lim Law; Siti Masrinda Tasirin; Wan Ramli Wan Daud; Derek Geldart

    2003-01-01

    This study reports the effect of vertical baffles on the group D powder mixing and drying characteristics in a batch fluidized bed dryer. Results obtained in this study showed that operating the fluidized bed dryer with vertical baffles gave better particle mixing. This is due to the fact that the vertical baffles acted to limit the growth of small bubbles into large bubbles and the small bubbles caused more vigorous mixing in the bed of particles before finally erupting at the bed surface. Thus, insertion of vertical baffles is a useful way to process group D particles in a fluidized bed, especially when the fluidized bed is large.

  11. DEVELOPMENT OF STEP-POOL SEQUENCE AND ITS EFFECTS IN RESISTANCE AND STREAM BED STABILITY

    Institute of Scientific and Technical Information of China (English)

    Zhao-Yin WANG; Jiang XU; Changzhi LI

    2004-01-01

    Experiments were conducted and field investigations were performed to study the development of step-pool sequence and its effects on resistance to the flow and stream bed stability. Step-pool sequence develops in incised channels as a result of streambed erosion, which is compared with sand dunes and armor layer of the role in resistance and streambed protection. The tight interlocking of particles in steps gives them an inherent stability which only extreme floods are likely to disturb. That stability suggests that step-pools are a valid equilibrium form, especially when coupled with their apparent regularity form and their role in satisfying the extreme condition of resistance maximization. The development degree of step-pools, SP, is proportional to the streambed slope. If the incoming sediment load is equal to or more than the sediment-carrying capacity of the flow, there is no bed erosion and thence there are no step-pools. Ifthe flow depth increases and is over the step-height the resistance caused by the step-pool sequence will be greatly reduced. The rate of energy dissipation by step-pools is a function of SP. The higher is SP, the larger is the rate of energy dissipation. The step-pool sequence increases the resistance and flow depth, reduces the shear stress of the flow and protects the streambed from erosion. Moreover,step-pool sequence provides ecologically sound habitats for aquatic bio-community as well.

  12. Effect of flushing condensate by bed water in Bakhar fields

    Energy Technology Data Exchange (ETDEWEB)

    Azimov, E.Kh.; Mamiyev, G.S.; Yusufzade, B.Kh.

    1984-01-01

    An analysis is made of the features of manifestation of elastic-water pressure mode and flooding of wells in the Bakhar field. Results are presented of operating a series of flooded wells illustrating the effects of flushing of the condensate that has fallen into the bed. The presence of individual interlayers causes selective advance of the water towards the well and results in spasmodic change in water recovery. The period of increased condensate content during flooding is 6-8 months and the additional extracted condensate can reach a high quantity.

  13. Slope gradient and shape effects on soil profiles in the northern mountainous forests of Iran

    Science.gov (United States)

    Fazlollahi Mohammadi, M.; Jalali, S. G. H.; Kooch, Y.; Said-Pullicino, D.

    2016-12-01

    In order to evaluate the variability of the soil profiles at two shapes (concave and convex) and five positions (summit, shoulder, back slope, footslope and toeslope) of a slope, a study of a virgin area was made in a Beech stand of mountain forests, northern Iran. Across the slope positions, the soil profiles demonstrated significant changes due to topography for two shape slopes. The solum depth of the convex slope was higher than the concave one in all five positions, and it decreased from the summit to shoulder and increased from the mid to lower slope positions for both convex and concave slopes. The thin solum at the upper positions and concave slope demonstrated that pedogenetic development is least at upper slope positions and concave slope where leaching and biomass productivity are less than at lower slopes and concave slope. A large decrease in the thickness of O and A horizons from the summit to back slope was noted for both concave and convex slopes, but it increased from back slope toward down slope for both of them. The average thickness of B horizons increased from summit to down slopes in the case of the concave slope, but in the case of convex slope it decreased from summit to shoulder and afterwards it increased to the down slope. The thicknesses of the different horizons varied in part in the different positions and shape slopes because they had different plant species cover and soil features, which were related to topography.

  14. Effect of static bed height in the upper fluidized bed on flow behavior in the lower riser section of a coupled reactor

    Institute of Scientific and Technical Information of China (English)

    Dewu Wang; Chunxi Lu; Chaoyu Yan

    2009-01-01

    To study olefin reduction by using an auxiliary reactor for FCC naphtha upgrading, a large-scale cold model of a riser-bed coupled to an upper fluidized bed was established. The effect of static bed height in the upper fluidized bed on particle flow behavior in the lower riser was investigated experimentally. A restriction index of solids holdup was used to evaluate quantitatively the restrictive effect of the upper fluidized bed. Experimental results show that, under the restrictive effect of the upper fluidized bed, the riser could be divided into three regions in the longitudinal direction: accelerating, fully developed and restriction. The axial distribution of solids holdup in the riser is characterized by large solids holdup in the top and bottom sections and small solids holdup in the middle section. Overall solids holdup increased with increasing static bed height in the upper fluidized bed, while particle velocity decreased. Such restrictive effect of the upper fluidized bed could extend from the middle and top sections to the whole riser volume when riser outlet resistance is increased, which increases with increasing static bed height in the upper fluidized bed. The upper bed exerts the strongest restriction on the area close to the riser outlet.

  15. Thermofluid effect on energy storage in fluidized bed reactor

    Science.gov (United States)

    Mahfoudi, Nadjiba; El Ganaoui, Mohammed; Moummi, Abdelhafid

    2016-05-01

    The development of innovative systems of heat storage is imperative to improve the efficiency of the existing systems used in the thermal solar energy applications. Several techniques were developed and realized in this context. The technology of the sand fluidized bed (sandTES) offers a promising alternative to the current state-of-the-art of the heat storage systems, such as fixed bed using a storage materials, as sand, ceramic, and stones, etc. Indeed, the use of the fluidization technique allows an effective heat transfer to the solid particles. With the sand, an important capacity of storage is obtained by an economic and ecological material [N. Mahfoudi, A. Moummi, M. El Ganaoui, Appl. Mech. Mater. 621, 214 (2014); N. Mahfoudi, A. Khachkouch, A. Moummi B. Benhaoua, M. El Ganaoui, Mech. Ind. 16, 411 (2015); N. Mahfoudi, A. Moummi, M. El Ganaoui, F. Mnasri, K.M. Aboudou, 3e Colloque internationale Francophone d"énergétique et mécanique, Comores, 2014, p. 91]. This paper presents a CFD simulation of the hydrodynamics and the thermal transient behavior of a fluidized bed reactor of sand, to determine the characteristics of storage. The simulation shows a symmetry breaking that occurs and gave way to chaotic transient generation of bubble formation after 3 s. Furthermore, the predicted average temperature of the solid phase (sand) increases gradually versus the time with a gain of 1 °C in an interval of 10 s. Contribution to the topical issue "Materials for Energy Harvesting, Conversion and Storage (ICOME 2015) - Elected submissions", edited by Jean-Michel Nunzi, Rachid Bennacer and Mohammed El Ganaoui

  16. Effect of slope on treetop detection using a LiDAR Canopy Height Model

    Science.gov (United States)

    Khosravipour, Anahita; Skidmore, Andrew K.; Wang, Tiejun; Isenburg, Martin; Khoshelham, Kourosh

    2015-06-01

    Canopy Height Models (CHMs) or normalized Digital Surface Models (nDSM) derived from LiDAR data have been applied to extract relevant forest inventory information. However, generating a CHM by height normalizing the raw LiDAR points is challenging if trees are located on complex terrain. On steep slopes, the raw elevation values located on either the downhill or the uphill part of a tree crown are height-normalized with parts of the digital terrain model that may be much lower or higher than the tree stem base, respectively. In treetop detection, a highest crown return located in the downhill part may prove to be a "false" local maximum that is distant from the true treetop. Based on this observation, we theoretically and experimentally quantify the effect of slope on the accuracy of treetop detection. The theoretical model presented a systematic horizontal displacement of treetops that causes tree height to be systematically displaced as a function of terrain slope and tree crown radius. Interestingly, our experimental results showed that the effect of CHM distortion on treetop displacement depends not only on the steepness of the slope but more importantly on the crown shape, which is species-dependent. The influence of the systematic error was significant for Scots pine, which has an irregular crown pattern and weak apical dominance, but not for mountain pine, which has a narrow conical crown with a distinct apex. Based on our findings, we suggest that in order to minimize the negative effect of steep slopes on the CHM, especially in heterogeneous forest with multiple species or species which change their morphological characteristics as they mature, it is best to use raw elevation values (i.e., use the un-normalized DSM) and compute the height after treetop detection.

  17. Effects of sand addition on turbulent flow over an immobile gravel bed

    Science.gov (United States)

    Wren, D. G.; Langendoen, E. J.; Kuhnle, R. A.

    2011-03-01

    The factors controlling the complex interaction of a coarse streambed with flow and sediment are difficult to measure. However, planning for reservoir flushing or dam removal requires knowledge of these interactions. In both cases, impounded sediments are introduced to channel beds that have had fine sediment particles removed without replacement. The channel bed pore space interacts with the flow and provides storage for particles. In order to address the need for information on such systems, an adjustable-slope, recirculating laboratory flume was used to study the changes in flow and turbulence caused by sand added to an immobile gravel bed. Detailed measurements were made using an acoustic Doppler velocimeter that collected three velocity components at a rate of 200 Hz. Because of the rough nature of the bed, individual velocity profiles varied significantly; therefore, in order to determine general trends, the data were spatially averaged over six 10 × 20 cm planes parallel to the bed with the lowest plane about 2 cm below the maximum gravel elevation. The increasing elevation of sand relative to the gravel layer resulted in decreased bed shear stress, decreased Reynolds stress, increased relative turbulence intensity, and a near-bed shift toward sweep-dominated turbulence.

  18. Quantifying Slopes with Digital Elevation Models of the Verdugo Hills, California: Effects of Resolution

    Science.gov (United States)

    Fielding, E. J.; Burbank, D. W.; Duncan, C. C.

    1996-01-01

    Quantification of surface slope angles is valuable in a wide variety of earth sciences. Slopes measured from digital elevation models (DEMs) or other topographic data sets depend strongly on the length scale or window size used in the slope calculations.

  19. The effect of 8 days of strict bed rest on the incretin effect in healthy volunteers

    DEFF Research Database (Denmark)

    Nielsen, Signe Tellerup; Harder-Lauridsen, Nina Majlund; Benatti, Fabiana Braga

    2016-01-01

    Bed rest and physical inactivity are the consequences of hospital admission for many patients. Physical inactivity induces changes in glucose metabolism, but its effect on the incretin effect, which is reduced in, e.g., Type 2 diabetes, is unknown. To investigate how 8 days of strict bed rest...... affects the incretin effect, 10 healthy nonobese male volunteers underwent 8 days of strict bed rest. Before and after the intervention, all volunteers underwent an oral glucose tolerance test (OGTT) followed by an intravenous glucose infusion (IVGI) on the following day to mimic the blood glucose profile...... difference between the area under the curve for the insulin response during the OGTT and that of the corresponding IVGI, respectively. Concentrations of glucose, insulin, C-peptide, and GIP measured during the OGTT were higher after the bed rest intervention (all P

  20. Effect of seat and table top slope on the biomechanical stress sustained by the musculo-skeletal system.

    Science.gov (United States)

    Hamaoui, Alain; Hassaïne, Myriam; Watier, Bruno; Zanone, Pier-Giorgio

    2016-01-01

    The purpose of this study was to assess the effect of table and seat slope on the biomechanical stress sustained by the musculo-skeletal system. Angular position of the head and trunk, and surface electromyography of eleven postural muscles were recorded while seated under different conditions of seat slope (0°, 15° forward) and table slope (0°, 20° backward). The specific stress sustained by C7-T1 joint was estimated with isometric torque calculation. The results showed that the backward sloping table was associated with a reduction of neck flexion and neck extensors EMG, contrasting with a concurrent overactivity of the deltoideus. The forward sloping chair induced an anterior pelvic tilt, but also a higher activity of the knee (vasti) and ankle (soleus) extensors. It was concluded that sloping chairs and tables favor a more erect posture of the spine, but entails an undesirable overactivity of upper and lower limbs muscles to prevent the body from sliding.

  1. The effect of chestnut coppice forests abandon on slope stability: a case study

    Science.gov (United States)

    Vergani, Chiara; Bassanelli, Chiara; Rossi, Lorenzo; Chiaradia, Enrico Antonio; Battista Bischetti, Gian

    2013-04-01

    Sweet chestnut has been fundamental for Italian mountainous economies for many centuries. This kind of forest was traditionally managed by coppicing in shortly rotation (15-20 years) to rapidly produce wood biomass until half of XX century. In the last decades these forests were in large part abandoned due to change in economy which made coppiced forest management unprofitable, especially in steeper slopes and where forest viability is scarce. As a consequence most of them are over aged and very dense, leading to an observed increasing in localized slope instability, primary because of the uprooting of stools (Vogt et al., 2006). In this work the effect of the abandon of chestnut coppice on slope stability was analyzed, focusing on shallow landslides triggering. The mechanical contribution to soil shear strength of differently managed chestnut stand was estimated and compared in terms of additional root cohesion. The study area is located in the Valcuvia Valley (Lombardy Prealps - Northern Italy) at an elevation about 600 m a.s.l., where two different stands, one managed and the other abandoned (over 40 year aged), were chosen. The two sampling stands are on cohesionless slopes (quaternary moraine deposits) and are homogeneous with regard to the substrate, exposure and elevation. Slope steepness influences heavily forestry practices and steeper stands are more frequently abandoned than stands on gentler terrain: in fact in the abandoned coppice the slope was higher (35 degrees against 13 in the managed stand) and no stands completely homogeneous can be found. In each site the main characteristics of the stand were surveyed and a trench in each stand was excavated to analyze root diameter and number distribution with depth; root specimens were also collected for the tensile force determination through laboratory tensile tests. Root distribution and force were then used to estimate root cohesion values through a Fiber Boundle Model (Pollen and Simon, 2005). Results

  2. Lithological effects in soil formation and soil slips on weathering-limited slopes underlain by granitic bedrocks in Japan

    OpenAIRE

    Wakatsuki, Tsuyoshi; Matsukura, Yukinori

    2008-01-01

    Soil slips occur every few years due to heavy rains on biotite granite (Gb) and hornblende biotite granite (Ghb) slopes in the Taga Mountains, Ibaraki Prefecture, Japan. The occurrence density of soil slips per unit area is 2.7 times greater in the Gb slopes than that in Ghb slopes. We examined the chemical, mineral, physical, and mechanical properties of two soil profiles on soil-slip scars in these slopes to study the effect of bedrock mineral composition on the density of soil slips. For a...

  3. The effective exponent gamma(Q) and the slope of the beta function

    CERN Document Server

    Stevenson, P M

    2016-01-01

    The slope of the beta function at a fixed point is commonly thought to be RG invariant and to be the critical exponent gamma* that governs the approach of any physical quantity R to its fixed-point limit: R*-R proportional to Q^gamma*. Chyla has shown that this is not quite true. Here we define a proper RG invariant, the "effective exponent" gamma(Q), whose fixed-point limit is the true gamma*.

  4. Effects of slope plate variable and reheating on semi-solid structure of ductile cast iron

    Institute of Scientific and Technical Information of China (English)

    M. Nili-Ahmadabadi; F. Pahlevani; P. Babaghorbani

    2008-01-01

    Semi-solid metal casting and forming are known as a promising process for a wide range of metal alloys production. In spite of growing application of semi-solid processed light alloys, a few works have been reported about semi-solid processing of iron and steel. In this research inclined plate was used to change dendritic structure of iron to globular one. The effects of length and slope of plate on the casting structure were examined. The results show that the process can effectively change the dendritic structure to globular. In the slope plate angle of 7.5°and length of 560 mm with cooling rate of 67K·s-1 the optimum nodular graphite and solid globular particle were achieved.The results also show that by using slope plate inoculant fading can be prevented more easily since the total time of process is rather short.In addition, the semi-solid ductile cast iron prepared by inclined plate method, was reheated to examine the effect of reheating conditions on the microstructure and coarsening kinetics of the alloy. Solid fraction at different reheating temperatures and holding time was obtained and based on these results the optimum reheating temperature range was determined.

  5. The effects of China's Sloping Land Conversion Program on agricultural households

    DEFF Research Database (Denmark)

    Liu, Zhen; Henningsen, Arne

    2016-01-01

    In the late 1990s, China aimed to mitigate environmental degradation from agricultural production activities by introducing the world's largest "Payments for Environmental Services" program: the Sloping Land Conversion Program (SLCP). We develop a microeconomic Agricultural Household Model, which...... nonfarm labor supply and total consumption in some regions, these effects could not be observed in others. The recent reduction of the SLCP compensation payment rates generally had negligible effects on agricultural production and off-farm work and only very small effects on household consumption....

  6. Effect of promoters on dynamics of gas-solid fluidized bed-Statistical and ANN approaches

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    In this study, a bubbling fluidized bed column, 99 mm in inside diameter and 960 mm in height, was used to investigate the effect of rod and disc promoters on fluctuation and expansion ratios. Factorial design (statistical approach) and artificial neural network (ANN) models were developed to predict the fluctuation and expansion ratios in this gas-solid fluidized bed with varying gas flow rates, bed heights, particle sizes and densities. The fluctuation and expansion predicted using these statistical and ANN models, for beds with and without promoters, were found to agree well with corresponding experiments. The statistical model was found to be superior to the ANN model due to its ability to take into account both individual and interactive effects. The rod promoters were found to be more effective in reducing bed fluctuation, and in increasing bed expansion at high gas mass velocities.

  7. The Effect of Increased Electrical Field Strength of 950 MHz Waves on the EPSP Slope

    Directory of Open Access Journals (Sweden)

    Seyed Mohammad Firoozabadi

    2009-03-01

    Full Text Available Introduction: Over the last decade, exposure to electromagnetic waves due to base station antennas has increased. This study was planned to evaluate the effects of different electrical field strengths with 950 MHz waves of the GSM mobile phone system on the excitatory postsynaptic potentiation (EPSP slope of the dentate gyrus long-term potentiation (LTP. Material and Methods: Twenty four naive male Wistar rats (3 months old, weighing 220 + 15 g were randomly divided into three groups (sham–exposed, GSM with 50.4 V/m and GSM with 60 V/m electrical field strength. The exposure program was carried out for 10 sessions during 3 days. The animals were exposed to the electromagnetic field for 45 minutes in a plastic chamber. Immediately after the exposure, anesthesia was induced for LTP induction and the field potentials were recorded for 60 minutes, then the EPSP slope and maintenance were analyzed. Results: Our data showed that whole-body exposure to 950 MHz waves of the GSM mobile phone system with 60 V/m electrical field strength could change the EPSP slope in rat brain hippocampus. Discussion and Conclusion: Increasing the electrical field strength could change synaptic plasticity and LTP characteristics in rat brain hippocampus.

  8. Green roof stormwater retention: effects of roof surface, slope, and media depth.

    Science.gov (United States)

    VanWoert, Nicholaus D; Rowe, D Bradley; Andresen, Jeffrey A; Rugh, Clayton L; Fernandez, R Thomas; Xiao, Lan

    2005-01-01

    Urban areas generate considerably more stormwater runoff than natural areas of the same size due to a greater percentage of impervious surfaces that impede water infiltration. Roof surfaces account for a large portion of this impervious cover. Establishing vegetation on rooftops, known as green roofs, is one method of recovering lost green space that can aid in mitigating stormwater runoff. Two studies were performed using several roof platforms to quantify the effects of various treatments on stormwater retention. The first study used three different roof surface treatments to quantify differences in stormwater retention of a standard commercial roof with gravel ballast, an extensive green roof system without vegetation, and a typical extensive green roof with vegetation. Overall, mean percent rainfall retention ranged from 48.7% (gravel) to 82.8% (vegetated). The second study tested the influence of roof slope (2 and 6.5%) and green roof media depth (2.5, 4.0, and 6.0 cm) on stormwater retention. For all combined rain events, platforms at 2% slope with a 4-cm media depth had the greatest mean retention, 87%, although the difference from the other treatments was minimal. The combination of reduced slope and deeper media clearly reduced the total quantity of runoff. For both studies, vegetated green roof systems not only reduced the amount of stormwater runoff, they also extended its duration over a period of time beyond the actual rain event.

  9. Effectiveness of fluidized pellet bed for removing soluble contaminants

    Institute of Scientific and Technical Information of China (English)

    WANG Xiaochang; LI Zhihua; WANG Zhen; LI Jinrong; LI Jiayu; CHEN Rong

    2009-01-01

    Fluidized pellet bed (FPB) has been successfully applied in water and wastewater treatment. However, the removal mechanism of contaminants especially the soluble ones, is still unclear. This study aimed to evaluate the effectiveness of FPB reactor for removing soluble contaminants from synthetic wastewater. By only coagulation through jar test operation with addition of polyaluminium chloride (PACl) as primary coagulant and polyacryamide (PAM) as coagulant-aid, the removals of soluble chemical oxygen demand (COD), suspended solids (SS), total phosphorus (TP), and NH4+-N were found to be only 2.2%--7.5%, 5.7%--25.5%, and 9.9%--18.5%, respectively. However, by FPB operation under the same dosage of coagulants, these values increased to 82.7%, 37.2%, and 50%, indicating that the formation of pellets in the FPB effectively enhanced the removal of soluble contaminants. By careful comparison of the settleablility and filterability of the pollutants after coagulation, the originally soluble contaminants could be divided into three groups, namely: (i) coagulated-and-settleable, (ii) coagulated-but-nonsettleable, and (iii) uncoagulable. It was found that not only the first two groups but also a large part of the third group could be effectively removed by FPB operation. However, the mechanism for the removal of the uncoagulable pollutants by FPB operation still needs further investigation.

  10. Cardiovascular consequences of bed rest: effect on maximal oxygen uptake

    Science.gov (United States)

    Convertino, V. A.

    1997-01-01

    Maximal oxygen uptake (VO2max) is reduced in healthy individuals confined to bed rest, suggesting it is independent of any disease state. The magnitude of reduction in VO2max is dependent on duration of bed rest and the initial level of aerobic fitness (VO2max), but it appears to be independent of age or gender. Bed rest induces an elevated maximal heart rate which, in turn, is associated with decreased cardiac vagal tone, increased sympathetic catecholamine secretion, and greater cardiac beta-receptor sensitivity. Despite the elevation in heart rate, VO2max is reduced primarily from decreased maximal stroke volume and cardiac output. An elevated ejection fraction during exercise following bed rest suggests that the lower stroke volume is not caused by ventricular dysfunction but is primarily the result of decreased venous return associated with lower circulating blood volume, reduced central venous pressure, and higher venous compliance in the lower extremities. VO2max, stroke volume, and cardiac output are further compromised by exercise in the upright posture. The contribution of hypovolemia to reduced cardiac output during exercise following bed rest is supported by the close relationship between the relative magnitude (% delta) and time course of change in blood volume and VO2max during bed rest, and also by the fact that retention of plasma volume is associated with maintenance of VO2max after bed rest. Arteriovenous oxygen difference during maximal exercise is not altered by bed rest, suggesting that peripheral mechanisms may not contribute significantly to the decreased VO2max. However reduction in baseline and maximal muscle blood flow, red blood cell volume, and capillarization in working muscles represent peripheral mechanisms that may contribute to limited oxygen delivery and, subsequently, lowered VO2max. Thus, alterations in cardiac and vascular functions induced by prolonged confinement to bed rest contribute to diminution of maximal oxygen uptake

  11. Hyperbolic Mild Slope Equations with Inclusion of Amplitude Dispersion Effect: Regular Waves

    Institute of Scientific and Technical Information of China (English)

    JIN Hong; ZOU Zhi-li

    2008-01-01

    A new form of hyperbolic mild slope equations is derived with the inclusion of the amplitude dispersion of nonlinear waves. The effects of including the amplitude dispersion effect on the wave propagation are discussed. Wave breaking mechanism is incorporated into the present model to apply the new equations to surf zone. The equations are solved numerically for regular wave propagation over a shoal and in surf zone, and a comparison is made against measurements. It is found that the inclusion of the amplitude dispersion can also improve model's performance on prediction of wave heights around breaking point for the wave motions in surf zone.

  12. EXTENDED MILD-SLOPE EQUATION

    Institute of Scientific and Technical Information of China (English)

    黄虎; 丁平兴; 吕秀红

    2001-01-01

    The Hamiltonian formalism for surface waves and the mild-slope approximation were empolyed in handling the case of slowly varying three-dimensional currents and an uneven bottom, thus leading to an extended mild-slope equation. The bottom topography consists of two components: the slowly varying component whose horizontal length scale is longer than the surface wave length, and the fast varying component with the amplitude being smaller than that of the surface wave. The frequency of the fast varying depth component is, however, comparable to that of the surface waves. The extended mild- slope equation is more widely applicable and contains as special cases famous mild-slope equations below: the classical mild-slope equation of Berkhoff , Kirby' s mild-slope equation with current, and Dingemans' s mild-slope equation for rippled bed. The extended shallow water equations for ambient currents and rapidly varying topography are also obtained.

  13. Use of Structure-from-Motion Photogrammetry Technique to model Danxia red bed landform slope stability by discrete element modeling - case study at Mt. Langshan, Hunan Province, China

    Science.gov (United States)

    Simonson, Scott; Hua, Peng; Luobin, Yan; Zhi, Chen

    2016-04-01

    Important to the evolution of Danxia landforms is how the rock cliffs are in large part shaped by rock collapse events, ranging from small break offs to large collapses. Quantitative research of Danxia landform evolution is still relatively young. In 2013-2014, Chinese and Slovak researchers conducted joint research to measure deformation of two large rock walls. In situ measurements of one rock wall found it to be stable, and Ps-InSAR measurements of the other were too few to be validated. Research conducted this year by Chinese researchers modeled the stress states of a stone pillar at Mt. Langshan, in Hunan Province, that toppled over in 2009. The model was able to demonstrate how stress states within the pillar changed as the soft basal layer retreated, but was not able to show the stress states at the point of complete collapse. According to field observations, the back side of the pillar fell away from the entire cliff mass before the complete collapse, and no models have been able to demonstrate the mechanisms behind this behavior. A further understanding of the mechanisms controlling rockfall events in Danxia landforms is extremely important because these stunning sceneries draw millions of tourists each year. Protecting the tourists and the infrastructure constructed to accommodate tourism is of utmost concern. This research will employ a UAV to as universally as possible photograph a stone pillar at Mt. Langshan that stands next to where the stone pillar collapsed in 2009. Using the recently developed structure-from-motion technique, a 3D model of the pillar will be constructed in order to extract geometrical data of the entire slope and its structural fabric. Also in situ measurements will be taken of the slope's toe during the field work exercises. These data are essential to constructing a realistic discrete element model using the 3DEC code and perform a kinematic analysis of the rock mass. Intact rock behavior will be based on the Mohr Coulomb

  14. 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.

  15. NUMERICAL STUDY ON EFFECT OF WAVING BED ON THE SURFACE WAVE

    Institute of Scientific and Technical Information of China (English)

    WU Zheng-ren; CHENG You-liang; WANG Song-ling

    2006-01-01

    The effect of the waving bed on the surface wave was investigated. The wave equation was reduced from the potential flow theory with the perturbation technique, and then was solved by using the pseudo-spectral method. The waterfall of the surface wave was simulated with the Matlab. It is shown that for the waving bed, an additional harmonic wave appears on the surface together with the solitary wave existing for the non-waving bed, and two kinds of waves do not interfere with each other. With the development of time, the waveform for the waving bed is kept invariable, and just the amplitude is reduced gradually. Wave-breaking phenomenon for the non-waving bed does not appear, so the waving bed seems useful to prevent the breaking of the wave.

  16. Effects of light polarization and waves slope statistics on the reflectance factor of the sea surface.

    Science.gov (United States)

    D'Alimonte, Davide; Kajiyama, Tamito

    2016-04-18

    Above-water radiometry depends on estimates of the reflectance factor ρ of the sea surface to compute the in situ water-leaving radiance. The Monte Carlo code for ocean color simulations MOX is used in this study to analyze the effect of different environmental components on ρ values. A first aspect is examining the reflectance factor without and by accounting for the sky-radiance polarization. The influence of the sea-surface statistics at discrete grid points is then considered by presenting a new scheme to define the variance of the waves slope. Results at different sun elevations and sensor orientations indicate that the light polarization effect on ρ simulations reduces from ∼17 to ∼10% when the wind speed increases from 0 to 14m s-1. An opposite tendency characterizes the modeling of the sea-surface slope variance, with ρ differences up to ∼12% at a wind speed of 10m s-1. The joint effect of polarization and the the sea-surface statistics displays a less systematic dependence on the wind speed, with differences in the range ∼13 to ∼18%. The ρ changes due to the light polarization and the variance of the waves slope become more relevant at sky-viewing geometries respectively lower and higher than 40° with respect to the zenith. An overall compensation of positive and negative offsets due to light polarization is finally documented when considering different sun elevations. These results address additional investigations which, by combining the modeling and experimental components of marine optics, better evaluate specific measurement protocols for collecting above-water radiometric data in the field.

  17. Effect of calcium on moving-bed biofilm reactor biofilms.

    Science.gov (United States)

    Goode, C; Allen, D G

    2011-03-01

    The effect of calcium concentration on the biofilm structure, microbiology, and treatment performance was evaluated in a moving-bed biofilm reactor. Three experiments were conducted in replicate laboratory-scale reactors to determine if wastewater calcium is an important variable for the design and optimization of these reactors. Biofilm structural properties, such as thickness, oxygen microprofiles, and the composition of extracellular polymeric substances (EPS) were affected by increasing calcium concentrations. Above a threshold concentration of calcium between 1 and 50 mg/L, biofilms became thicker and denser, with a shift toward increasingly proteinaceous EPS at higher calcium concentrations up to 200 mgCa2+/L. At 300 mgCa2+/L, biofilms were found to become primarily composed of inorganic calcium precipitates. Microbiology was assessed through microscopy, denaturing grade gel electrophoresis, and enumeration of higher organisms. Higher calcium concentrations were found to change the bacterial community and promote the abundant growth of filamentous organisms and various protazoa and metazoan populations. The chemical oxygen demand removal efficiency was improved for reactors at calcium concentrations of 50 mg/L and above. Reactor effluents for the lowest calcium concentration (1 mgCa2+/L) were found to be turbid (>50 NTU), as a result of the detachment of small and poorly settling planktonic biomass, whereas higher concentrations promoted settling of the suspended phase. In general, calcium was found to be an important variable causing significant changes in biofilm structure and reactor function.

  18. Rainfall infiltration on hilly slopes under various lithology and its effect on tree growth in the dry-hot valley

    Institute of Scientific and Technical Information of China (English)

    YANG; Zhong; XIONG; Donghong; ZHOU; Hongyi; ZHANG; Xinbao

    2003-01-01

    Revegetation is very difficult in dry-hot valleys in China. Rainfall infiltration capability on hilly slopes is one of the key factors determining soil moisture conditions and tree growth in the dry-hot valley. Low rainfall infiltration often results in soil drought on slopes under the dry-hot valleys climate. Rainfall infiltration capability varies greatly with the difference of slope lithologic porosity. The infiltration rates of five lithologic slope-types, Schist Slope, Grit Slope, Gravel Slope, the slightly eroded Mudstone Slope and the intensively eroded Mudstone Slope, are 1.40-8.67, 6.33, 0.69-2.20, 0.6-1.3 and 0.03-0.63 mm/min, respectively. With its viscid compact soil body and low infiltration capability which causes little infiltrating rainfall, mudstone slope can afford little effective supply to soil water and leads to serious drought of soil in dry seasons, resulting in cessation of growth or even wide-spread death of trees due to physiological damage for the excessive deficit of water in dry season and also the low productivity of stands. Hence, it is extremely difficult to restore vegetation on this type of slope. The other four lithologic slope-types, however, with well-developed soil crevice, high infiltration capability and thus more infiltrating rainfall, can afford more available soil water supply and the trees on them can obtain better growth and relatively higher productivity, compared with those on Mudstone Slope. Revegetation in dry-hot valleys is controlled by the soil moisture conditions of different slope-types, and it can be implemented by relying on the dominative life-form plant species, the suitable spatial arrangement of different life-forms of arbor-shrub-herb species, and the establishment of ecological community relationship between vegetation and soil moisture in habits. On the other hand, ground making measures for forestation and the runoff-collecting engineering measures to increase the rainfall infiltration are the major

  19. The large-scale shaking table test study of dynamic response and failure mode of bedding rock slope under earthquake%地震作用下顺层岩质边坡动力响应和破坏模式大型振动台试验研究

    Institute of Scientific and Technical Information of China (English)

    董金玉; 杨国香; 伍法权; 祁生文

    2011-01-01

    It is necessary to study bedding rock landslides induced by "5-12" Wenchuan earthquake. According to the similar relationship of dynamic model test, a bedding model slope is built with a height of 1.6 m, length of 1.75 m, width of 0.8 m and a slope angle larger than the dip angle of the rock stratum. A large-scale shaking table test of the model slope is performed. The results show that amplification coefficients of the acceleration along slope surface and in vertical direction increase with the elevation increasing. And its increment speeds also increase with the elevation increasing. At the same elevation, the amplification coefficients of the acceleration on slope surface are larger than that in slope body. The input frequency of seismic waves has obvious effects on dynamic responses of slope. The amplification effect of acceleration enhances evidently with the frequency increasing and approach to the natural frequency of the model slope. The amplification coefficients of the acceleration decrease with the earthquake amplitudes increasing. Comparing with the acceleration monitoring data obtained by the shaking table test of the homogeneous slope, it is found that structural surface of the slope also has effects on the amplification coefficients of the acceleration. Because of reflection and refraction of structural surface, the amplification effect of acceleration enhances evidently. Based on analysis of failure features of the slope, the failure process is described as earthquake induction-loosening of rock mass and tensile failure of the crest of the slope-propagation and coalescence of cracks in the middle part of slope surface-occurrence of high locality landslide-formation of debris flow-accumulation at the slope toe. The study results are helpful to reveal the formation mechanism of landslide under earthquake and provide valuable references for disaster prevention and reduction.%5·12汶川大地震触发了大量的顺层岩质滑坡,对其进行研究

  20. Thermal field of the Joule-Thomson effect under conditions of bed cooling

    Energy Technology Data Exchange (ETDEWEB)

    Sharafutdinov, R.F.; Filippov, A.I.

    1983-01-01

    Features are examined of the thermal field for the Joule-Thomson effect under bed conditions when there is cooling by injected water. It is indicated that the time for establishing the temperature significantly depends on the thermophysical properties of the bed and underlying rocks. Results of calculations of the temperature relationship for different conditions of well operation are presented.

  1. Geometrical volume effects in the computation of the slope of the Isgur-Wise function

    Energy Technology Data Exchange (ETDEWEB)

    Lellouch, L. [Southampton Univ. (United Kingdom). Dept. of Physics; Nieves, J. [Southampton Univ. (United Kingdom). Dept. of Physics; Sachrajda, C.T. [Southampton Univ. (United Kingdom). Dept. of Physics; Stella, N. [Southampton Univ. (United Kingdom). Dept. of Physics; Wittig, H. [Southampton Univ. (United Kingdom). Dept. of Physics; Martinelli, G. [Dipartimento di Fisica, Universita di Roma `La Sapienza`, 00185 Rome (Italy); Richards, D.G. [Department of Physics, The University of Edinburgh, Edinburgh EH9 3JZ, Scotland (United Kingdom); UKQCD Collaboration

    1995-06-19

    We use a method recently suggested for evaluating the slope of the Isgur-Wise function, at the zero-recoil point, on the lattice. The computations are performed in the quenched approximation to lattice QCD, on a 24{sup 3} x48 lattice at {beta}=6.2, using an O(a)-improved action for the fermions. We have found unexpectedly large finite-volume effects in such a calculation. These volume corrections turned out to be purely geometrical and independent of the dynamics of the system. After the study of these effects on a smaller volume and for different quark masses, we give approximate expressions that account for them. Using these approximations we find {xi}{sup `}(1)=-1.7{sup +2}{sub -2} and {xi}{sup `}(1)=-1.4{sup +2}{sub -1} for the slope of the Isgur-Wise function, for two mesons composed of a heavy quark slightly heavier and lighter, respectively, than the charm quark, and in both cases, a light antiquark whose mass is about that of the strange quark. ((orig.)).

  2. Non-linear effects on solute transfer between flowing water and a sediment bed.

    Science.gov (United States)

    Higashino, Makoto; Stefan, Heinz G

    2011-11-15

    A previously developed model of periodic pore water flow in space and time, and associated solute transport in a stream bed of fine sand is extended to coarse sand and fine gravel. The pore water flow immediately below the sediment/water interface becomes intermittently a non-Darcy flow. The periodic pressure and velocity fluctuations considered are induced by near-bed coherent turbulent motions in the stream flow; they penetrate from the sediment/water interface into the sediment pore system and are described by a wave number (χ) and a period (T) that are given as functions of the shear velocity (U(∗)) between the flowing water and the sediment bed. The stream bed has a flat surface without bed forms. The flow field in the sediment pore system is described by the continuity equation and a resistance law that includes both viscous (Darcy) and non-linear (inertial) effects. Simulation results show that non-linear (inertial) effects near the sediment/water interface increase flow resistance and reduce mean flow velocities. Compared to pure Darcy flow, non-linear (inertial) effects reduce solute exchange rates between overlying water and the sediment bed but only by a moderate amount (less than 50%). Turbulent coherent flow structures in the stream flow enhance solute transfer in the pore system of a stream bed compared to pure molecular diffusion, but by much less than standing surface waves or bed forms.

  3. Summer Monsoon and Annual Variability of Sea Surface Slope and Their Effects on Alongshore Current near Qingdao

    Institute of Scientific and Technical Information of China (English)

    蒲书箴; 程军; 张义钧; 石强; 骆敬新; 范文静

    2004-01-01

    Based on the monthly mean sea level data obtained from 3 years′ (1999-2001) tide-gauge measurements, the annual variability of the sea level near Qingdao and Jiaozhou Bay is studied and discussed in this paper. Results show that the sea surface height at all the tide gauges becomes higher in summer than that in winter,with an obvious seasonal variability.Furthermore the sea surface height measured at a short distance outside the bay is lower than that in thebay, showing a sea surface slope downward from north to south. The reasons for the formation of the slope are explained as well, The dynamic action ofthe summer monsoon and the sea surface slope, and their effects on the monthly mean current are studied by means of dynamics principles. The importance of the summer monsoon and the pressure gradient generated by the sea surface slope, with their effects on the alongshore current, is pointed out and emphasized in this paper.

  4. Effect of the slope and initial moisture content on soil loss, aggregate and particle size distribution

    Science.gov (United States)

    Szabó, Judit Alexandra; Jakab, Gergely; Szabó, Boglárka

    2015-04-01

    Soil structure degradation has effect through the soil water balance and nutrient supply on the agricultural potential of an area. The soil erosion process comprises two phases: detachment and transport by water. To study the transport phase nozzle type laboratory-scale rainfall simulator was used with constant 80 mmhr-1 intensity on an arable haplic Cambisol. Measuring the aggregate and particle size distribution of the soil loss gives a good approach the erosion process. The primary objective of this study was to examine the sediment concentration, and detect the quality and quantity change of the soil loss during a single precipitation under six treatment combinations (recently tilled and crusty soil surface on two different slope steepness, inland inundation and drought soil conditions). Soil loss were collected continually, and separated per aggregate size fractions with sieves in three rounds during a rain to measure the weights. The particle size distribution was measured with Horiba LA-950 particle size analyzer. In general the ratio of the macro aggregates decreases and the ratio of the micro aggregates and clay fraction increases in the sediment with time during the precipitation due to the raindrop impact. Sediment concentration depends on the slope steepness, as from steeper slopes the runoff can transport bigger amount of sediment, but from the tilled surface bigger aggregates were washing down. Micro aggregate fraction is one of the indicators of good soil structure. The degradation of micro aggregates occurs in steeper slopes and the most erosive time period depends on the micromorphology of the surface. And while the aggregate size distribution of the soil loss of the treatments shows high variety of distribution and differs from the original soil, the particle size distribution of each aggregate size fraction shows similar trends except the 50-250 µm fraction where the fine sand fraction is dominating instead of the loam. This anomaly may be

  5. Effect of impulse and bedding on impact toughness of coal

    Institute of Scientific and Technical Information of China (English)

    YU Yong-jiang; WANG Lai-gui; LI Jian-xin

    2008-01-01

    In order to understand the properties of impact toughness of coal at different impact speeds,and the change of impact toughness of lump coal to joint directivity of lump coal,a series of impact tests were conducted on Beijing Da'anshan Lump Coal at different impact speeds and in different impact direction.Through analyzing the test result,it is shown that the change of testing samples is similar when impact is exerted on the vertical bedding and the parallel bedding when the impulse is less than 20 Nos,and the difference increases with the impulse increasing when the impulse is more than 20 Nos.At the same time,the expanding energy of fracture in samples increases with its expanding speed,and the expanding energy of fracture has close relation with the impact direction of the tested samples.And the difference of impact toughness of lump coal produced by different impact direction increase with the impact speed.The fracture surface of lump coal when impact is exerted on the vertical bedding is smooth and the broken block number is fewer;but the fracture surface of lump coal when impact is exerted on the parallel bedding isn't smooth and the broken block number is more,which inflects impact toughness of coal is sensitive to some deficiency.

  6. Effect of impulse and bedding on impact toughness of coal

    Institute of Scientific and Technical Information of China (English)

    YU Yong-jiang; WANG Lai-gui; LI Jian-xin

    2008-01-01

    In order to understand the properties of impact toughness of coal at different impact speeds, and the change of impact toughness of lump coal to joint directivity of lump coal, a series of impact tests were conducted on Beijing Da'anshan Lump Coal at different impact speeds and in different impact direction. Through analyzing the test result, it is shown that the change of testing samples is similar when impact is exerted on the vertical bedding and the parallel bedding when the impulse is less than 20 Nos, and the difference increases with the impulse increasing when the impulse is more than 20 Nos. At the same time, the expanding energy of fracture in samples increases with its expanding speed, and the expanding energy of fracture has close relation with the impact direction of the tested samples. And the difference of impact toughness of lump coal produced by different im-pact direction increase with the impact speed. The fracture surface of lump coal when im-pact is exerted on the vertical bedding is smooth and the broken block number is fewer; but the fracture surface of lump coal when impact is exerted on the parallel bedding isn't smooth and the broken block number is more, which inflects impact toughness of coal is sensitive to some deficiency.

  7. Nonequilibrium effects in fixed-bed interstitial fluid dispersion

    NARCIS (Netherlands)

    Kronberg, A.E.; Westerterp, K.R.

    1999-01-01

    Continuum models for the role of the interstitial fluid with respect to mass and heat dispersion in a fixed bed are discussed. It is argued that the departures from local equilibrium and not the concentration and temperature gradients as such should be considered as the driving forces for mass and h

  8. The feedback effect caused by bed load on a turbulent liquid flow

    CERN Document Server

    Franklin, Erick de Moraes; Rosa, Eugênio Spanó

    2016-01-01

    Experiments on the effects due solely to a mobile granular layer on a liquid flow are presented (feedback effect). Nonintrusive measurements were performed in a closed conduit channel of rectangular cross section where grains were transported as bed load by a turbulent water flow. The water velocity profiles were measured over fixed and mobile granular beds of same granulometry by Particle Image Velocimetry. The spatial resolution of the measurements allowed the experimental quantification of the feedback effect. The present findings are of importance for predicting the bed-load transport rate and the pressure drop in activities related to the conveyance of grains.

  9. Hyperbolic Mild Slope Equations with Inclusion of Amplitude Dispersion Effect: Random Waves

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    New hyperbolic mild slope equations for random waves are developed with the inclusion of amplitude dispersion. The frequency perturbation around the peak frequency of random waves is adopted to extend the equations for regular waves to random waves. The nonlinear effect of amplitude dispersion is incorporated approximately into the model by only considering the nonlinear effect on the carrier waves of random waves, which is done by introducing a representative wave amplitude for the carrier waves. The computation time is greatly saved by the introduction of the representative wave amplitude. The extension of the present model to breaking waves is also considered in order to apply the new equations to surf zone. The model is validated for random waves propagate over a shoal and in surf zone against measurements.

  10. Effect of Slope Position on Soil Properties and Types Along an Elevation Gradient of Arasbaran Forest, Iran

    Directory of Open Access Journals (Sweden)

    Hossein Rezaei

    2015-01-01

    Full Text Available Sustainable development by forest managing need to identify forest ecosystem elements. Forest soil is the most important element of forest ecosystem that has key roles in forest managing. Therefore, studying of soil properties and evolution under different environmental conditions is necessary for sustainable management of forest ecosystems. Spatial variation of soil properties is significantly influenced by some environmental factors that slope position is one of them. The aim of this study was evaluating effects of slope position on forest soil change which was carried out in Arasbaran forest, North-West of Iran. Nine soil profiles were dug, described and sampled in three different parts of an altitudinal transect with same environmental conditions and different slope positions. Then soil samples were analysed physicaly and chemicaly and so classified based on Soil Taxonomy 2014. Also according to obtained results One-way analysis of variance was used to test relations of soil properties and slope positions. This results revealed significant effect of slope positions on thickness of the soil profile and solum, clay, organic carbon and total nitrogen percentages and cation exchange capacity at 5% level of confidence which lead to change of type, depth and sequence of soil horizons along altitudinal transect. Finally, it has found that slope position not only has important role in soil properties changes and soil evolution but also it can't be refused the various role and influence of same forest stand in different slope positions. Therefore various soils such as Inceptisols, Alfisols and Molisols were observed under different slope positions. Then it can be achieved that, because of special forest vegetation, soil evolution along altitudinal transect of forest ecosystems are differing from other ecosystems. Thus, for forest soil management program it is necessary to consider both of topography and vegetation effect over the area, even if one of

  11. Tracking bed bugs (Cimex lectularius): a study of the effect of physiological and extrinsic factors on the response to bed bug-derived volatiles.

    Science.gov (United States)

    Weeks, E N I; Logan, J G; Birkett, M A; Pickett, J A; Cameron, M M

    2013-02-01

    The common bed bug, Cimex lectularius, feeds on the blood of mammal and bird hosts, and is a pest of global importance. Semiochemicals are chemicals involved in animal communication that may affect behaviour and/or physiology. Attractive semiochemicals that play a role in mediating bed bug behaviour could be exploited for the development of a highly effective novel monitoring device. Tracking software was used to record the response of bed bugs to volatiles from paper previously exposed to conspecific bugs in a still-air olfactometer illuminated by infrared lights, through a variety of activity variables. The effect of time of day as an extrinsic factor, and sex, stage, mating status and nutritional status as physiological factors on the response of bed bugs to the volatiles was examined. Bed bugs of both sexes and all stages responded to the volatiles from bed bug-exposed papers, showing significant attraction and orientation towards the volatile source whether they were starved or engorged. Confirmation that the physiological factors examined do not affect the response of bed bugs to the volatiles from bed bug-exposed papers provides evidence that these bed bug-derived volatiles contain aggregation cues, as semiochemicals that promote aggregation should by definition be detected by both sexes and all life stages. A device baited with such semiochemicals could play a major role in limiting the impact of the current bed bug resurgence by enabling timely detection of infestations, along with quantitative evaluation of control and effective surveillance of the geographical distribution of the pest species.

  12. Effects of Rainfall Intensity and Slope Gradient on Runoff and Soil Moisture Content on Different Growing Stages of Spring Maize

    Directory of Open Access Journals (Sweden)

    Wenbin Mu

    2015-06-01

    Full Text Available The rainfall-runoff process (RRP is an important part of hydrologic process. There is an effective measure to study RRP through artificial rainfall simulation. This paper describes a study on three growing stages (jointing stage, tasseling stage, and mature stage of spring maize in which simulated rainfall events were used to study the effects of various factors (rainfall intensity and slope gradient on the RRP. The RRP was tested with three different rainfall intensities (0.67, 1.00, and 1.67 mm/min and subjected to three different slopes (5°, 15°, and 20° so as to study RRP characteristics in semiarid regions. Regression analysis was used to study the results of this test. The following key results were obtained: (1 With the increase in rainfall intensity and slope, the increasing relationship with rainfall duration, overland flow, and cumulative runoff, respectively, complied with logarithmic and quadratic functions before reaching stable runoff in each growing stage of spring maize; (2 The runoff coefficient increased with the increase in rainfall intensity and slope in each growing stages of spring maize. The relationship between runoff coefficient, slope, rainfall intensity, rainfall duration, antecedent soil moisture, and vegetation coverage was multivariate and nonlinear; (3 The runoff lag time decreased with the increase in rainfall intensity and slope within the same growing stage. In addition, the relationship between runoff lag time, slope, rainfall intensity, antecedent soil moisture, and vegetation coverage could also be expressed by a multivariate nonlinear equation; (4 The descent rate of soil infiltration rate curve increased with the increased rainfall intensity and slope in the same growing stage. Furthermore, by comparing the Kostiakov, Horton, and Philip models, it was found that the Horton infiltration model was the best for estimating soil infiltration rate and cumulative infiltration under the condition of test.

  13. Effects of basin bottom slope on jet hydrodynamics and river mouth bar formation

    Science.gov (United States)

    Jiménez-Robles, A. M.; Ortega-Sánchez, M.; Losada, M. A.

    2016-06-01

    River mouth bars are strategic morphological units primarily responsible for the development of entire deltaic systems. This paper addresses the role of receiving basin slope in the hydrodynamics of an exiting sediment-laden turbulent jet and in resulting mouth bar morphodynamics. We use Delft3D, a coupled hydrodynamic and morphodynamic numerical model, along with a theoretical formulation to reproduce the physics of the problem, characterized by a fluvially dominated inlet free of waves and tides. We propose an updated theoretical model with a slope-dependent entrainment coefficient, showing that the rate at which ambient fluid is incorporated into a jet increases with higher basin slopes. Transient results reveal that the magnitude of a basin slope can alter the stability of a jet, favoring the formation of an unstable meandering jet. While a stable jet gives rise to "middle-ground" bars accompanied by diverging channels, a "lunate" mouth bar results from unstable jets. Additional morphodynamic simulations demonstrate that the time required for mouth bar stagnation in its final position increases linearly with the basin slope. In contrast, the distance at which the mouth bar eventually forms decreases until reaching an asymptotic value for slopes higher than 2%. Moreover, the basin slope highly influences sedimentary processes responsible for bar formation: for milder slopes, progradation processes prevail, while in steeper basins aggradation is more relevant. Finally, the minimum relative water depth over a bar crest that forces the flow to bifurcate around a fully developed bar decreases with the basin slope.

  14. CNPC Develops Effective Coal-bed Methane Techniques

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    The technology for recovery of coal-bed methane developed by China National Petroleum Corporation (CNPC), which is the parent company of PetroChina, will help the nation lower reliance on overseas companies and better position itself to produce that resource at a low cost. Trapped in coal deposits, the special type of methane is one among several types of high-energy unconventional gases that are expected to become important sources of the country's energy.

  15. The Effects of Terrain Slope and Orientation on Different Weather Processes in China under Different Model Resolutions

    Institute of Scientific and Technical Information of China (English)

    HUANG Danqing; QIAN Yongfu

    2009-01-01

    Currently, short wave radiation at the ground surface (GSW) is calculated under the assumption of a horizontal surface. This method of estimating the GSW may lead to considerable errors when the model resolution becomes higher and the model terrain becomes steeper. In this paper, to improve the short wave solar radiation simulations, a terrain slope and orientation parameterization has been implemented into the non-hydrostatic mesoscale model GRAPES (Global/Regional Assimilation and Prediction System). The effects of the terrain slope and orientation on different short range weather processes in China under differentmodel resolutions are simulated and discussed. In the simulations, topography height is taken from NCEP (National Centers for Environmental Prediction) with a resolution of 1 kin, and the slope and orientation of terrain are calculated using different staggering schemes and under different weather conditions. The results show that when the model resolution is low (30 and 60 kin) and the slope of terrain is not large, the influence of the slope and orientation of terrain on the GSW is not evident; otherwise, however, it is not negligible.Under high model resolutions (3 and 6 kin), the increase (decrease) of simulated precipitation corresponds to the decrease (increase) of the GSW induced by the slope effect, and the variations of precipitation are usually ranged between -5 and 5 mm. Under the high resolution, the surface temperature and heat fluxes are strongly correlated to each other and the high correlation exists mostly in the complex terrain regions. The changes of the GSW, precipitation, surface temperature, and heat fluxes induced by the effects of the terrain slope and orientation are more obvious in mountainous regions, due to the alternations in the atmospheric circulation. It is found as well that under the weather condition of less cloud and less precipitation, the effects of the terrain slope and orientation can be more realistically seen

  16. Negative priming effect on organic matter mineralisation in NE Atlantic slope sediments.

    Directory of Open Access Journals (Sweden)

    Evangelia Gontikaki

    Full Text Available The priming effect (PE is a complex phenomenon which describes a modification (acceleration or retardation in the mineralisation rate of refractory organic matter (OM following inputs of labile material. PEs are well-studied in terrestrial ecosystems owing to their potential importance in the evolution of soil carbon stocks but have been largely ignored in aquatic systems despite the fact that the prerequisite for their occurrence, i.e. the co-existence of labile and refractory OM, is also true for sediments. We conducted stable isotope tracer experiments in continental margin sediments from the NE Atlantic (550-950 m to study PE occurrence and intensity in relation to labile OM input. Sediment slurries were treated with increasing quantities of the (13C-labelled diatom Thalassiosira rotula and PE was quantified after 7, 14 and 21 days. There was a stepwise effect of diatom quantity on its mineralisation although mineralisation efficiency dropped with increasing substrate amounts. The addition of diatomaceous OM yielded a negative PE (i.e. retardation of existing sediment OM mineralisation at the end of the experiment regardless of diatom quantity. Negative PE is often the result of preferential utilisation of the newly deposited labile material by the microbial community ("preferential substrate utilization", PSU which is usually observed at excessive substrate additions. The fact that PSU and the associated negative PE occurred even at low substrate levels in this study could be attributed to limited amounts of OM subject to priming in our study area (~0.2% organic carbon [OC] which seems to be an exception among continental slopes (typically >0.5%OC. We postulate that PEs will normally be positive in continental slope sediments and that their intensity will be a direct function of sediment OC content. More experiments with varying supply of substrate targeting C-poor vs. C-rich sediments are needed to confirm these hypotheses.

  17. Effects of Immersed Surfaces on the Combustor Efficiency of Small-Scale Fluidized Beds

    OpenAIRE

    Nurdil Eskin; Afsin Gungor

    2005-01-01

    In this study, effects of the different types of heat exchanger surfaces on the second law efficiency of a small-scale circulating fluidized bed (CFB) combustor are analyzed and the results are compared with the bubbling fluidized bed coal combustor effectiveness values. Using a previously developed simulation program, combustor efficiency and entropy generation values are obtained at different operation velocities at different height and volume ratios of the immersed surfaces, both for circu...

  18. Effect of forest vegetation on runoff and sediment production in sloping lands of Loess area

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xiaoming; YU Xinxiao; WU Sihong; WEI Tianxing; ZHANG Xuepei

    2006-01-01

    According to fixed-position data for 1985-2003 from nine runoff plots of Caijiachuan watershed which lies in Jixian County of Shanxi Province in Loess area,this paper studied the relationship between vegetation and runoff and sediment production in sloping lands in detail,which helps to provide scientific basis for vegetation m-construction and studies on environmental transformation of water and sediment in watersheds of Loess area.Although,many study results testify that forest vegetation has an important function in soil and water conservation and cutting runoff,the effect of vegetation on runoff and sediment transmission is complicated,and this needs to be studied in depth.The results of the paper showed the following.Firstly,the natural secondary forest performs better function of soil and water conservation than artificial Robinia pseudoacacia forest,and runoff and sediment produced in the former in individual rainfall were 65%-82% and 23%-92% of those pro duced in the latter.At the same time,better correlative relationship between runoff and sediment production and rainfall and rainfall intensity were testified by multiple regression,but the correlation decreased gradually with the increase of canopy density of forest.Secondly,the difference of runoff and sediment production in several land use types was very distinct,and the amount of runoff and sediment produced from Ostryopsis davidiana forest and natural secondary forest were the least,and runoff and sediment produced from in artificial Robinia pseudoacacia forest and Pinus tabulaeformis forest were 5-fold as much as those from O.davidiana forest.Besides,runoff and sediment produced in mixed planting of apple trees and crops were 16.14-fold and 2.96-fold than those of O.davidiana forest,respectively,but the amount decreased obviously after high-standard soil preparation in the case of the former.Thirdly,based on gray cognate analyses of factors affecting runoff and sediment production in sloping land

  19. Quantification of the bed load effects on turbulent open-channel flows

    Science.gov (United States)

    Liu, Detian; Liu, Xiaofeng; Fu, Xudong; Wang, Guangqian

    2016-04-01

    With a computational model combining large eddy simulation and a discrete element model, detailed quantification of the bed load effects on turbulent open-channel flows is presented. The objective is the revelation of bed load particle impact on the mean flow properties and coherent structures. Two comparative numerical experiments with mobile and immobile beds are conducted. Mean properties (e.g., velocity and Reynolds stress profiles) show good agreement with experimental data. Comparing the mobile and immobile cases, the effective bed position is nearly the same, whereas the equivalent sand roughness is changed. The flow experiences higher bottom shear stress over immobile bed. To quantify impact on turbulent structures, a revised quadrant analysis is performed to calculate four key parameters of ejection and sweep events (duration, maximum shear stress, transported momentum, and period). Results show that the ejection and sweep events have comparable importance in the outer region. However, sweep becomes dominant in the near-wall region. The motion of particles enhances the sweep dominance by breaking up the ejection structures and decreasing their occurrence ratio. The results also suggest that the ejection events are easier to be influenced by the particle motions because they originate from the near-wall region. The duration, maximum shear stress, and transported momentum decrease close to the bed. The period remains relatively constant in the outer region but decreases near the bed. Visualization of the coherent structure reveals that the instantaneous particle motion has strong correlation with the bursting cycle events.

  20. Exercise Effects on the Course of Gray Matter Changes Over 70 Days of Bed Rest

    Science.gov (United States)

    Koppelmans, V.; Ploutz-Snyder, L.; DeDios, Y. E.; Wood, S. J.; Reuter-Lorenz, P. A.; Kofman, I.; Bloomberg, J. J.; Mulavara, A. P.; Seidler, R. D.

    2014-01-01

    Long duration spaceflight affects posture control, locomotion, and manual control. The microgravity environment is an important causal factor for spaceflight induced sensorimotor changes through direct effects on peripheral changes that result from reduced vestibular stimulation and body unloading. Effects of microgravity on sensorimotor function have been investigated on earth using bed rest studies. Long duration bed rest serves as a space-flight analogue because it mimics microgravity in body unloading and bodily fluid shifts. It has been hypothesized that the cephalad fluid shift that has been observed in microgravity could potentially affect central nervous system function and structure, and thereby indirectly affect sensorimotor or cognitive functioning. Preliminary results of one of our ongoing studies indeed showed that 70 days of long duration head down-tilt bed rest results in focal changes in gray matter volume from pre-bed rest to various time points during bed rest. These gray matter changes that could reflect fluid shifts as well as neuroplasticity were related to decrements in motor skills such as maintenance of equilibrium. In consideration of the health and performance of crewmembers both inand post-flight we are currently conducting a study that investigates the potential preventive effects of exercise on gray matter and motor performance changes that we observed over the course of bed rest. Numerous studies have shown beneficial effects of aerobic exercise on brain structure and cognitive performance in healthy and demented subjects over a large age range. We therefore hypothesized that an exercise intervention in bed rest could potentially mitigate or prevent the effects of bed rest on the central nervous system. Here we present preliminary outcomes of our study.

  1. IN THE FLUIDIZED BED THE EFFECT OF SOLID QUANTITY ON THE HEIGHT OF BED AND SOLID OF RATE

    Directory of Open Access Journals (Sweden)

    Kamil Bekir KOÇ

    1999-01-01

    Full Text Available In the process of meeting the growing demand for electric power and heat, coal will play an increasingly important role in the world wide. Fluidized combustion offers a clean and relatively inexpensive method for coal combustion, a method insensitive to fuel quality and capable of reducing sulfur and nitric oxides emission. At the work, a prototype fluid bed was produced and the distance between the holes had been narrower towards to the center of the distributor sieve in order to balance the distribution of the air. Later on, the quantity of the coal was decreased continuously and at the end of the measurements, the heights of the solids and the rates of the solid had been defined and the effects of the coal quantity had been investigated.

  2. Performance optimization of dense-array concentrator photovoltaic system considering effects of circumsolar radiation and slope error.

    Science.gov (United States)

    Wong, Chee-Woon; Chong, Kok-Keong; Tan, Ming-Hui

    2015-07-27

    This paper presents an approach to optimize the electrical performance of dense-array concentrator photovoltaic system comprised of non-imaging dish concentrator by considering the circumsolar radiation and slope error effects. Based on the simulated flux distribution, a systematic methodology to optimize the layout configuration of solar cells interconnection circuit in dense array concentrator photovoltaic module has been proposed by minimizing the current mismatch caused by non-uniformity of concentrated sunlight. An optimized layout of interconnection solar cells circuit with minimum electrical power loss of 6.5% can be achieved by minimizing the effects of both circumsolar radiation and slope error.

  3. The Effects of Long Duration Bed Rest on Brain Functional Connectivity and Sensorimotor Functioning

    Science.gov (United States)

    Cassady, K.; Koppelmans, V.; De Dios, Y.; Stepanyan, V.; Szecsy, D.; Gadd, N.; Wood, S.; Reuter-Lorenz, P.; Castenada, R. Riascos; Kofman, I.; Bloomberg, J.; Mulavara, A; Seidler, R.

    2016-01-01

    Long duration spaceflight has been associated with detrimental alterations in human sensorimotor functioning. Prolonged exposure to a head-down tilt (HDT) position during long duration bed rest can resemble several effects of the microgravity environment such as reduced sensory inputs, body unloading and increased cephalic fluid distribution. The question of whether microgravity affects other central nervous system functions such as brain functional connectivity and its relationship with behavior is largely unknown, but of importance to the health and performance of astronauts both during and post-flight. In the present study, we investigate the effects of prolonged exposure to HDT bed rest on resting state brain functional connectivity and its association with behavioral changes in 17 male participants. To validate that our findings were not due to confounding factors such as time or task practice, we also acquired resting state functional magnetic resonance imaging (rs-fMRI) and behavioral measurements from 14 normative control participants at four time points. Bed rest participants remained in bed with their heads tilted down six degrees below their feet for 70 consecutive days. Rs-fMRI and behavioral data were obtained at seven time points averaging around: 12 and 8 days prior to bed rest; 7, 50, and 70 days during bed rest; and 8 and 12 days after bed rest. 70 days of HDT bed rest resulted in significant increases in functional connectivity during bed rest followed by a reversal of changes in the post bed rest recovery period between motor cortical and somatosensory areas of the brain. In contrast, decreases in connectivity were observed between temporoparietal regions. Furthermore, post-hoc correlation analyses revealed a significant relationship between motor-somatosensory network connectivity and standing balance performance changes; participants that exhibited the greatest increases in connectivity strength showed the least deterioration in postural

  4. Effectiveness of sloping agricultural land technology on soil fertility status of mid-hills in Nepal

    Institute of Scientific and Technical Information of China (English)

    Kiran Lamichhane

    2013-01-01

    Hedgerows with intercropping systems were established at the ICIMOD test and demonstration site at Godawari to assess the effective-ness of Sloping Agricultural Land Technology (SALT) in reducing run-off water volume, controlling soil loss, increasing crop production, and improving soil fertility in the mid-hills of Nepal. Runoff water volume (1996-2002), soil loss (1996-2002) and maize yield (1995-2001), and soil fertility-related parameters were assessed on SALT models with three factors:the type of nitrogen-fixing plant, the farmers’ practice, and fertilizer use. Results showed a significant effect of Alnus nepalensis and/or Indigofera dosua on runoff water volume, soil loss, crop produc-tion, soil water retention, and soil nutrients (NPK). Farmers’ practice and fertilization did not play a significant role in reducing runoff water and soil loss. However, farmers’ practice significantly increased crop produc-tion. Therefore, integrating soil conservation approaches on SALT sys-tems enhances stable economic output to hills and mountain farmers.

  5. Success-slope effects on the illusion of control and on remembered success-frequency

    Directory of Open Access Journals (Sweden)

    Anastasia Ejova

    2013-07-01

    Full Text Available The illusion of control refers to the inference of action-outcome contingency in situations where outcomes are in fact random. The strength of this illusion has been found to be affected by whether the frequency of successes increases or decreases over repeated trials, in what can be termed a ``success-slope'' effect. Previous studies have generated inconsistent findings regarding the nature of this effect. In this paper we present an experiment (N = 334 that overcomes several methodological limitations within this literature, employing a wider range of dependent measures (measures of two different types of illusory control, primary (by self and secondary (by luck, as well as measures of remembered success-frequency. Results indicate that different dependent measures lead to different effects. On measures of (primary, but not secondary control over the task, scores were highest when the rate of success increased over time. Meanwhile, estimates of success-frequency in the task did not vary across conditions and showed trends consistent with the broader literature on human memory.

  6. Effect of rainfall regime and slope on runoff in a gullied loess region on the Loess Plateau in China.

    Science.gov (United States)

    Fang, H Y; Cai, Q G; Chen, H; Li, Q Y

    2008-09-01

    Runoff was measured from seven plots with different slopes nested in Tuanshangou catchment on the Loess Plateau to study effect of slopes on runoff in relation to rainfall regimes. Based on nine years of field observation and K-mean clusters, 84 rainfall events were grouped into three rainfall regimes. Rainfall regime A is the group of events with strong rainfall intensity, high frequency, and short duration. Rainfall regime C consists of events with low intensity, long duration, and infrequent occurrence. Rainfall regime B is the aggregation of events of medium intensity and medium duration, and less frequent occurrence. The following results were found: (1) Different from traditional studies, runoff coefficient neither decreased nor increased, but presented peak value on the slope surfaces; (2) For individual plot, runoff coefficients induced by rainfall regime A were the highest, and those induced by rainfall regime C were the lowest; Downslope, the runoff coefficients induced by three rainfall regimes presented the same changing trend, although the peak value induced by regime A occurred on a shorter slope length compared to those by regime B and C; (3) Scale effect on runoff induced by rainfall regime A was the least, and that induced by rainfall regime C was the largest. These results can be explained by the interactions of crusting, soil moisture content, slope length and gradient, and erosion units, etc., in the context of different rainfall regimes.

  7. Tube array heat transfer in fluidized beds; a study of particle size effects

    Energy Technology Data Exchange (ETDEWEB)

    Chung, T.Y.; Welty, J.R. (Oregon State Univ., Corvallis, OR (USA). Dept. of Mechanical Engineering)

    1989-07-01

    Experiments were performed with an array of horizontal tubes, arranged in a regular equilateral triangular pattern, immersed in a fluidized bed operating at 812 {Kappa}. Data are reported for heat transfer between the bed and a centrally-located tube in the array. Both total and radiative heat transfer rates were measured for superficial velocities spanning the range from packed bed conditions to over twice the minimum fluidization velocity. Results are presented for five different-size particles. Local heat transfer values, measured around the tube periphery, and integrated averages are reported for all test conditions. Comparisons are also made between the heat transfer behavior of a tube in an array and that for a single tube in a hot fluidized bed under the same overall operating conditions. The results of this comparison suggests that the two mechanisms, gas convection and radiation, are competing effects.

  8. Effect of soil management systems on erosion and nutrition loss in vineyards on steep slopes.

    Science.gov (United States)

    Vrsic, Stanko; Ivancic, Anton; Pulko, Borut; Valdhuber, Janez

    2011-05-01

    Green cover in vineyards on steep slopes may play an important role in the reduction of soil erosion. The main objective of this study was to investigate the effect of a permanent green cover (PGC) on soil erosion, together with any loss of nutrients, and to compare it with periodic soil tillage (PST). PST took place in the spring (May) and summer (August), in each second area between rows, in a vineyard with permanent green cover. In the case of PST experimental treatments, on average, 1892 kg of soil ha-1 yr-1 eroded, together with the nutrients. In the case of PGC treatments, the amountof soil erosion was only 92 kg ha-1 yr-1. The greater portion of erosive events occurred after tillage in summer, which was accompanied by heavy rainfall and slow renewal of grass cover (slower than in spring). PGC treatment provided a better environment for the activities of soil macro-organisms (i.e., earthworms belonging to the family Lumbricidae), and mostof the organisms were close to the soil surface. In PST treatment, the majority of macro-organisms were below the area disturbed by the tillage (between 10 and 20 cm). The results of our investigation indicate that, in order to adjust wine production activities to climatic changes in vineyards with permanent green cover, PST in area between rows is more advisable in spring (end of May) than in summer (first decade of August) owing to an earlier establishment of effective grass cover.

  9. The experiment study on slippage effect of the coal-bed methane transfusion

    Energy Technology Data Exchange (ETDEWEB)

    Peng, X.; Pan, Y.; Xiao, C.; Chen, C. [Liaoning Technical University, Fuxin (China). College of Science

    2008-12-15

    When gas flows in a compact porous medium at low speed, it has a slippage effect which is caused by molecular collisions of gas with the solid skeleton. Using the gas transfusion slippage effect for researching coal bed transfusion, a mathematical model of the coal bed was established which considered the slippage effect. The experiment indicates that the higher the surrounding pressure, the more marked is the slippage effect. At the same condition of axial pressure and surrounding pressure, with an increase of the hole pressure, the coal permeability become higher and then lower. The coal body effective stress and the permeability curve also has the same change tendency. Thus the conclusion can be drawn that the transfusion of the gas in the coal bed generally has a slippage effect. 5 refs., 3 figs.

  10. Snowpack spatial variability: Towards understanding its effect on remote sensing measurements and snow slope stability

    Science.gov (United States)

    Marshall, Hans-Peter

    on a slope. The ability to accurately characterize snowpack properties at much higher resolutions and spatial extent than previously possible will hopefully help lead to a more complete understanding of spatial variability, its effect on remote sensing measurements and snow slope stability, and result in improvements in avalanche prediction and accuracy of SWE estimates from space.

  11. Effective grouting area of jointed slope and stress deformation responses by numerical analysis with FLAC3D

    Institute of Scientific and Technical Information of China (English)

    ZHU Zi-qiang; LIU Qun-yi; ZENG Fan-he; QING Du-gan

    2009-01-01

    To study the grouting reinforcement mechanism in jointed rock slope, first, the theoretical deduction was done to calculate the critical length of slipping if the slope angle is larger than that of joint inclination; Second, the numerical calculation model was founded by FLAG3D, so as to find the stress and deformation responses of rock mass in the state before and after grouting, the analysis results show that the range between the boundary of critical slipping block and the joint plane that passes the slope toe is the effective grouting area (EGA). After excavation, large deformation occurs along the joint plane. After grouting, the displacements of rock particles become uniform and continuous, and large deformations along the joint plane are controlled; the dynamic displacement can reflect the deformation response of slope during excavation in the state before and after grouting, as well as the shear location of potential slip plane. After grouting, the dynamic displacement of each monitoring point reaches the peak value with very few time steps,which indicate that the parameters of the joint plane, such as strength and stiffness, are improved; the stress field becomes uniform. Tensile area reduces gradually; whole stability of the slope and its ability to resist tensile and shear stress are improved greatly.

  12. Effects of Rainfall Characteristics on the Stability of Tropical Residual Soil Slope

    Directory of Open Access Journals (Sweden)

    Rahardjo Harianto

    2016-01-01

    Full Text Available Global climate change has a significant impact on rainfall characteristics, sea water level and groundwater table. Changes in rainfall characteristics may affect stability of slopes and have severe impacts on sustainable urban living. Information on the intensity, frequency and duration of rainfall is often required by geotechnical engineers for performing slope stability analyses. Many seepage analyses are commonly performed using the most extreme rainfall possible which is uneconomical in designing a slope repair or slope failure preventive measure. In this study, the historical rainfall data were analyzed and investigated to understand the characteristics of rainfall in Singapore. The frequency distribution method was used to estimate future rainfall characteristics in Singapore. New intensity-duration-frequency (IDF curves for rainfall in Singapore were developed for six different durations (10, 20, 30 min and 1, 2 and 24 h and six frequencies (2, 5, 10, 25, 50 and 100 years. The new IDF curves were used in the seepage and slope stability analyses to determine the variation of factor of safety of residual soil slopes under different rainfall intensities in Singapore.

  13. The experiment study on slippage effect of the coal-bed methane transfusion

    Institute of Scientific and Technical Information of China (English)

    PENG Xiao-hua; PAN Yi-shan; XIAO Xiao-chun; CHEN Chang-hua

    2008-01-01

    When the gas flow in the compact porous medium at low speed,it has slippage effect which is caused by the gas molecular collision whit the solidskeleton.Using the gas transfusion slippage effect at researching the coal bed transfusion rule,established the transfusion mathematical model of the coal bed which had considered the slippage effect.Observing the influence of the different toencircle presses,the different hole press and the different actual stress to the coal bed by using the three-axles permeameter.Thus summarized the transfusion rule of the coal bed.The experiment indicates that the bigger of the surrounding pressure,the more obvious of the slippage effect.At the same condition of axial pressure and the surrounding pressure,with the increase of the hole pressure,the coal permeability became bigger and then smaller.The coal body effective tress and the permeability curve nearly also has the same change tendency.Thus we can draws the conclusion that the transfusion of the gas in the coal bed generally has the slippage effect.

  14. The experiment study on slippage effect of the coal-bed methane transfusion

    Institute of Scientific and Technical Information of China (English)

    PENG Xiao-hua; PAN Yi-shan; XIAO Xiao-chun; CHEN Chang-hua

    2008-01-01

    When the gas flow in the compact porous medium at low speed, it has slippage effect which is caused by the gas molecular collision whit the solidskeleton. Using the gas transfusion slippage effect at researching the coal bed transfusion rule, established the transfusion mathematical model of the coal bed which had considered the slippage effect. Observing the influence of the different toencircle presses, the different hole press and the different actual stress to the coal bed by using the three-axles permeameter. Thus sum-marized the transfusion rule of the coal bed. The experiment indicates that the bigger of the surrounding pressure, the more obvious of the slippage effect. At the same condition of axial pressure and the surrounding pressure, with the increase of the hole pressure, the coal permeability became bigger and then smaller. The coal body effective tress and the permeability curve nearly also has the same change tendency. Thus we can draws the conclusion that the transfusion of the gas in the coal bed generally has the slippage effect.

  15. Estimation of infiltration rate, run-off and sediment yield under simulated rainfall experiments in upper Pravara Basin, India: Effect of slope angle and grass-cover

    Indian Academy of Sciences (India)

    Veena U Joshi; Devidas T Tambe

    2010-12-01

    The main objective of this study is to measure the effect of slope and grass-cover on in filtration rate, run-off and sediment yield under simulated rainfall conditions in a badland area located in the upper Pravara Basin in western India. An automatic rainfall simulator was designed following Dunne et al (1980) and considering the local conditions. Experiments were conducted on six selected experimental fields of 2 × 2 m within the catchment with distinct variations in surface characteristics –grass-covered area with gentle slope, recently ploughed gently sloping area, area covered by crop residue (moderate slope), bare badland with steep slope, gravelly surface with near flat slope and steep slope with grass-cover. The results indicate subtle to noteworthy variations amongst the plots depending on their slope angle and surface characteristics. An important finding that emerges from the study is that the grass-cover is the most effective measure in inducing infiltration and in turn minimizing run-off and sediment yield. Sediment yields are lowest in gently sloping grass-covered surfaces and highest in bare badland surfaces with steep slopes. These findings have enormous implication for this area, because over 2/3 area is characterized by bare and steep slopes.

  16. Effects of Soil-Vegetation-Atmosphere Interaction on the Stability of a Clay Slope: A Case Study

    Directory of Open Access Journals (Sweden)

    Pedone Giuseppe

    2016-01-01

    Full Text Available Deep and slow landslide processes are frequently observed in clay slopes located along the Southern Apennines (Italy. A case study representative of these processes, named Pisciolo case study, is discussed in the paper. The geo-hydro-mechanical characteristics of the materials involved in the instability phenomena are initially discussed. Pluviometric, piezometric, inclinometric and GPS monitoring data are subsequently presented, suggesting that rainfall infiltration constitutes the main factor inducing slope movements. The connection between formation of landslide bodies and slope-atmosphere interaction has been demonstrated through a hydro-mechanical finite element analysis, whose results are finally reported in the work. This analysis has been conducted employing a constitutive model that is capable of simulating both saturated and unsaturated soil behaviour, as well as a boundary condition able to simulate the effects of the soil-vegetation-atmosphere interaction.

  17. Effects of image orientation and ground control points distribution on unmanned aerial vehicle photogrammetry projects on a road cut slope

    Science.gov (United States)

    Carvajal-Ramírez, Fernando; Agüera-Vega, Francisco; Martínez-Carricondo, Patricio J.

    2016-07-01

    The morphology of road cut slopes, such as length and high slopes, is one of the most prevalent causes of landslides and terrain stability troubles. Digital elevation models (DEMs) and orthoimages are used for land management purposes. Two flights with different orientations with respect to the target surface were planned, and four photogrammetric projects were carried out during these flights to study the image orientation effects. Orthogonal images oriented to the cut slope with only sidelaps were compared to the classical vertical orientation, with sidelapping, endlapping, and both types of overlapping simultaneously. DEM and orthoimages obtained from the orthogonal project showed smaller errors than those obtained from the other three photogrammetric projects, with the first one being much easier to manage. One additional flight and six photogrammetric projects were used to establish an objective criterion to locate the three ground control points for georeferencing and rectification DEMs and orthoimages. All possible sources of errors were evaluated in the DEMs and orthoimages.

  18. Cost-effective temporary microirrigation system for grass establishment on environmentally sensitive steep slopes

    Energy Technology Data Exchange (ETDEWEB)

    Gyasi-Agyei, Y. [University of Central Queensland, Rockhampton, Qld. (Australia). James Goldston Faculty of Engineering & Physical Systems

    2004-05-15

    An advanced technology cost-effective drip irrigation system design and setup on environmentally sensitive elevated steep slopes (batters) of a coal train derailment site in Central Queensland, Australia, are presented. The final profile of the coal burial site consists of six batters and associated berms with a drop in elevation of about 35 m. A small dam constructed downstream of the confluence of the two main drainage channels at the site supplied water for irrigation of the batters to aid the establishment of grass to control erosion. Water was periodically pumped from the small dam to three storage tanks using a petrol (gas) pump. Three solar pumps drew water from the storage tanks and dam to irrigate the top four batters. Contactors, pressure switches and irrigation control valves in turn shared a single solar power source between the solar pumps. Level balls (floating switches) placed in the storage tanks cut the solar power supply to the pumps when the storage tanks were nearly empty. On the whole, the irrigation system worked very well and excellent grass cover was established within 12 weeks. Given the environmental risks associated with the on-site burying of coal, and the estimated cost of about AU$11.73/m{sup 2} (every 10 years) in maintenance if the railway batters are not treated, the estimated total cost of AU$4.61/m{sup 2} of batter area treated with irrigation, including AU$3.08/m{sup 2} in irrigation cost, is justified.

  19. Integrating the effects of forest cover on slope stability in a deterministic landslide susceptibility model (TRIGRS 2.0)

    Science.gov (United States)

    Zieher, T.; Rutzinger, M.; Bremer, M.; Meissl, G.; Geitner, C.

    2014-12-01

    The potentially stabilizing effects of forest cover in respect of slope stability have been the subject of many studies in the recent past. Hence, the effects of trees are also considered in many deterministic landslide susceptibility models. TRIGRS 2.0 (Transient Rainfall Infiltration and Grid-Based Regional Slope-Stability; USGS) is a dynamic, physically-based model designed to estimate shallow landslide susceptibility in space and time. In the original version the effects of forest cover are not considered. As for further studies in Vorarlberg (Austria) TRIGRS 2.0 is intended to be applied in selected catchments that are densely forested, the effects of trees on slope stability were implemented in the model. Besides hydrological impacts such as interception or transpiration by tree canopies and stems, root cohesion directly influences the stability of slopes especially in case of shallow landslides while the additional weight superimposed by trees is of minor relevance. Detailed data on tree positions and further attributes such as tree height and diameter at breast height were derived throughout the study area (52 km²) from high-resolution airborne laser scanning data. Different scenarios were computed for spruce (Picea abies) in the study area. Root cohesion was estimated area-wide based on published correlations between root reinforcement and distance to tree stems depending on the stem diameter at breast height. In order to account for decreasing root cohesion with depth an exponential distribution was assumed and implemented in the model. Preliminary modelling results show that forest cover can have positive effects on slope stability yet strongly depending on tree age and stand structure. This work has been conducted within C3S-ISLS, which is funded by the Austrian Climate and Energy Fund, 5th ACRP Program.

  20. Effects of Bed Rest on Conduction Velocity of the Triceps Surae Stretch Reflex and Postural Control

    Science.gov (United States)

    Reschke, M. F.; Wood, S. J.; Cerisano, J. M.; Kofman, I. S.; Fisher, E. A.; Esteves, J. T.; Taylor, L. C.; DeDios, Y. E.; Harm, D. L.

    2011-01-01

    Despite rigorous exercise and nutritional management during space missions, astronauts returning from microgravity exhibit neuromuscular deficits and a significant loss in muscle mass in the postural muscles of the lower leg. Similar changes in the postural muscles occur in subjects participating in long-duration bed rest studies. These adaptive muscle changes manifest as a reduction in reflex conduction velocity during head-down bed rest. Because the stretch reflex encompasses both the peripheral (muscle spindle and nerve axon) and central (spinal synapse) components involved in adaptation to calf muscle unloading, it may be used to provide feedback on the general condition of neuromuscular function, and might be used to evaluate the effectiveness of countermeasures aimed at preserving muscle mass and function during periods of unloading. Stretch reflexes were measured on 18 control subjects who spent 60 to 90 days in continuous 6 deg head-down bed rest. Using a motorized system capable of rotating the foot around the ankle joint (dorsiflexion) through an angle of 10 degrees at a peak velocity of about 250 deg/sec, a stretch reflex was recorded from the subject's left triceps surae muscle group. Using surface electromyography, about 300 reflex responses were obtained and ensemble-averaged on 3 separate days before bed rest, 3 to 4 times in bed, and 3 times after bed rest. The averaged responses for each test day were examined for reflex latency and conduction velocity (CV) across gender. Computerized posturography was also conducted on these same subjects before and after bed rest as part of the standard measures. Peak-to-peak sway was measured during Sensory Organization Tests (SOTs) to evaluate changes in the ability to effectively use or suppress visual, vestibular, and proprioceptive information for postural control. Although no gender differences were found, a significant increase in reflex latency and a significant decrease in CV were observed during the bed

  1. Electrocatalysts based on Ru nanoparticles : effect of methanol on the ORR Tafel slope

    Energy Technology Data Exchange (ETDEWEB)

    Duron-Torres, S.M.; Leyva-Noyola, F.; Galvan-Valencia, M. [Univ. Autonoma de Zacatecas, Guadalupe, Zacatecas (Mexico). U.A. de Ciencias Quimicas; Solorza-Feria, O. [Centro de Investigacion y Estudios Avanzados del I.P.N., Col. San Pedro Zacatenco (Mexico). Depto. de Quimica

    2008-04-15

    Proton Exchange Membrane Fuel Cells (PEMFCs) are promising candidates in systems that require small-sized power sources such as non-stationary electronic equipment and transportation. However, the scientific and technical challenges of PEMFC which include diminution of catalytic charges, catalyst substitution, membrane development, optimization of bipolar plates and a global cost decrease require further study. A strategic approach that will help with the diffusion and assimilation of the PEMFC technology involves the use of fuel other than hydrogen in cells such as methanol. However, the use of methanol in direct methanol fuel cells (DMFC) presents further challenges including slow kinetics in both anodic and cathodic reactions, and fuel crossover due to exchange membrane alcohol permeability, meaning a lower global efficiency of DMFC as compared with the hydrogen fuel cell. This article provided a contribution to the synthesis and characterization of novel catalytic materials research for DMFC. A series of materials based on ruthenium (Ru) nanoparticles were produced and catalytically studied in a multielectron charge transfer process. These materials are electroactive for the oxygen reduction reaction (ORR) in acid medium and methanol tolerant as well. The Ru nanoparticles and some binary and ternary mixtures with platinum (Pt) and cobalt (Co) were obtained by a pyrolysis procedure of solid precursors at 190 degrees Celsius. Physiochemical characterization was conducted by using a scanning electronic microscopy and energy dispersion spectroscopy mapping. Kinetic parameters of the cathodic reaction in a 0.5M sulfuric acid solution at different methanol concentrations were compared using electrochemical characterization with cyclic voltammetry and rotating disc electrodes. It was concluded that methanol has a major effect on the ORR electrocatalytic activity on binary Ru-Pt materials with a higher Pt proportion. In addition, the methanol effect on the Tafel slope

  2. Bed Stability and Debris Flow Erosion: A Dynamic "Shields Criterion" Associated with Bed Structure

    Science.gov (United States)

    Longjas, A.; Hill, K. M.

    2015-12-01

    Debris flows are mass movements that play an important role in transporting sediment from steep uplands to rivers at lower slopes. As the debris flow moves downstream, it entrains materials such as loose boulders, gravel, sand and mud deposited locally by shorter flows such as slides and rockfalls. To capture the conditions under which debris flows entrain bed sediment, some models use something akin to the Shields' criterion and an excess shear stress of the flow. However, these models typically neglect granular-scale effects in the bed which can modify the conditions under which a debris flow is erosional or depositional. For example, it is well known that repeated shearing causes denser packing in loose dry soils, which undoubtedly changes their resistance to shear. Here, we present laboratory flume experiments showing that the conditions for entrainment by debris flows is significantly dependent on the aging of an erodible bed even for narrowly distributed spherical particles. We investigate this quantitatively using particle tracking measurements to quantify instantaneous erosion rates and the evolving bed structure or "fabric". With progressive experiments we find a signature that emerges in the bed fabric that is correlated with an increasing apparent "fragility" of the bed. Specifically, a system that is originally depositional may become erosional after repeated debris flow events, and an erodible bed becomes increasingly erodible with repeated flows. We hypothesize that related effects of bed aging at the field scale may be partly responsible for the increasing destructiveness of secondary flows of landslides and debris flows.

  3. Comparative Study of Guizhou Sloping Land Soil and Water Conservation Effect of the Three Cropping Patterns

    Institute of Scientific and Technical Information of China (English)

    Zhenggang; CHEN; Yanhua; XIONG; Jian; LI; Qing; ZHU

    2013-01-01

    Surface cover degree,monthly variation of topsoil water content,loss of soil and nutrient in alfalfa-corn intercropping,strip rotation cropping and corn monoculture were studied in this paper. Then soil and water conservation effect of these planting modes were compared. Results showed that surface cover degree was high during the all rainy season in both alfalfa-corn intercropping and strip rotation cropping mode, with slope field covered by vegetation all the year round. Roots of alfalfa grew well,which not only improved the root biomass in 0-20cm layer,enhanced the capacity of the infiltration of rainwater to soil,protected biodiversity,but also reduced surface off and soil erosion of 39. 3% and 59. 3% . Strip rotation cropping could also reduce surface off and soil erosion of 10. 4% and 21. 3% . Both alfalfa-corn intercropping and strip rotation cropping increased soil moisture in rainy season and before rainy season,whilst reduced loss of organic matter (caused by soil erosion) of 29. 9%-52. 4% ,total N of 26. 7%-54. 9% ,total K of 27. 3%-70. 9% ,slow available K of 21. 4%-58. 9% ,increased corn production of 33. 0%-35. 9% . Moreover,there was 13664kg/hm 2 in alfalfa-corn intercropping,which was 4. 1 times higher than common mode. There was 12492 kg/hm 2 in strip rotation cropping which was 2. 7 times higher than common mode.

  4. Effects of biofilm on flow over and through a permeable bed

    Science.gov (United States)

    Kazemifar, Farzan; Blois, Gianluca; Aybar, Marcelo; Perez-Calleja, Patricia; Nerenberg, Robert; Sinha, Sumit; Hardy, Richard; Best, James; Sambrook-Smith, Gregory; Christensen, Kenneth

    2016-11-01

    Biofilms constitute an important form of bacterial life in aquatic environments and are present at the interface of fluids and solids, such as riverbeds. Biofilms are permeable, heterogeneous, and deformable structures that can influence the flow and mass/momentum transport, yet their interaction with flow is not fully understood in part due to technical obstacles impeding quantitative experimental investigations. The porosity of river beds results in the generation of a diverse mosaic of 'suction' and 'ejection' events that are far removed from typical assumptions of turbulent flow structure over an impermeable bed. In this work, the effect of biofilm on bed permeability is studied. Experiments are conducted in a closed water channel equipped with 4-cm-deep permeable bed models consisting of horizontal cylinders normal to the bulk flow direction, forming an idealized two-dimensional permeable bed. Prior to conducting flow experiments, the models are placed within an independent biofilm reactor to initiate and control the biofilm growth. Once a targeted biofilm growth stage is achieved, the models are transferred to the water channel and subjected to transitional and turbulent flows. Long-distance microscopic particle image velocimetry measurements are performed to quantify the effect of biofilm on the turbulence structure of the free flow as well as the freestream-subsurface flow interaction.

  5. Effect of a flow-corrective insert on the flow pattern in a pebble bed reactor

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yu; Gui, Nan; Yang, Xingtuan [Institute of Nuclear and New Energy Technology, Collaborative Innovation Center of Advanced Nuclear Energy Technology, Key Laboratory of Advanced Reactor Engineering and Safety of Ministry of Education, Tsinghua University, Beijing 100084 (China); Tu, Jiyuan [Institute of Nuclear and New Energy Technology, Collaborative Innovation Center of Advanced Nuclear Energy Technology, Key Laboratory of Advanced Reactor Engineering and Safety of Ministry of Education, Tsinghua University, Beijing 100084 (China); School of Aerospace, Mechanical & Manufacturing Engineering, RMIT University, Melbourne 3083, VIC (Australia); Jiang, Shengyao, E-mail: shengyaojiang@sina.com [Institute of Nuclear and New Energy Technology, Collaborative Innovation Center of Advanced Nuclear Energy Technology, Key Laboratory of Advanced Reactor Engineering and Safety of Ministry of Education, Tsinghua University, Beijing 100084 (China)

    2016-04-15

    Highlights: • Effect of an insert on improving flow uniformity and eliminating stagnant zone is studied. • Three values concerned with the stagnant zone, radial uniformity and flow sequence are used. • Outlet diameter is a critical parameter that determines balancing mechanism of the insert. • Height/location is varied to let the insert work in unbalanced region and avoid adverse effect. - Abstract: A flow-corrective insert is adopted in the pebble-bed high temperature gas-cooled reactor (HTGR) to improve flow performance of the pebble flow for the first time. 3D discrete element method (DEM) modeling is employed to study this slow and dense granular flow. It is verified that locating a properly designed insert in the bed can help transform unsatisfactory flow field to the preferred flow pattern for pebble bed reactors. Three characteristic values on the stagnant zone, radial uniformity and flow sequence of pebble flow are defined to evaluate uniformity of the overall flow field quantitatively. The results demonstrate that the pebble bed equipped with an insert performs better than normal beds from all these three aspects. Moreover, based on numerical experiments, several universal tips for insert design on height, location and outlet diameter are suggested.

  6. The effect of different methods of seed bed preparation on greenhouse cucumber yield and yield components

    Directory of Open Access Journals (Sweden)

    D. Momeni

    2010-12-01

    Full Text Available To investigate the effects of different methods of seed bed preparation on yield of greenhouse cucumber, a two-year long experiment was conducted as a randomized complete block design with four replications in Jiroft from 2004. Different methods of seed bed preparation were as follows: 1 ridge with 20 cm height and 50 cm width and 2 plant rows with 40 cm distance, 2 furrow with 20 cm depth and 50 cm width and 2 plant rows inside, with 40 cm distance, and 3 planting on flat area with 40 cm distance. The results showed that the effect of planting bed on yield of greenhouse cucumber was significant. Furrow and flat area increased yield significantly, compared to the ridge treatment. Analysis of yield components such as plant height, number of pickling fruits, number of leaves, photosynthetic area and number of flowers showed that they are all correlated with fruit yield. The number of pickling fruits was significantly more in furrow and flat area than in ridge treatment. The height of cucumber plants on flat bed was significantly higher than that of the other treatments. The number of leaves and photosynthetic area of plants on flat bed were significantly greater than those in the other treatments. The least dead plants due to fungi disease were observed in ridge treatment. In view of yield and its components under the condition of this experiment, it can be concluded that flat area and furrow treatments are better than ridge treatment.

  7. Effect of graph generation on slope stability analysis based on graph theory

    Institute of Scientific and Technical Information of China (English)

    Enpu Li; Xiaoying Zhuang; Wenbo Zheng; Yongchang Cai

    2014-01-01

    Limit equilibrium method (LEM) and strength reduction method (SRM) are the most widely used methods for slope stability analysis. However, it can be noted that they both have some limitations in practical application. In the LEM, the constitutive model cannot be considered and many assumptions are needed between slices of soil/rock. The SRM requires iterative calculations and does not give the slip surface directly. A method for slope stability analysis based on the graph theory is recently developed to directly calculate the minimum safety factor and potential critical slip surface according to the stress results of numerical simulation. The method is based on current stress state and can overcome the disadvantages mentioned above in the two traditional methods. The influences of edge generation and mesh geometry on the position of slip surface and the safety factor of slope are studied, in which a new method for edge generation is proposed, and reasonable mesh size is suggested. The results of bench-mark examples and a rock slope show good accuracy and efficiency of the presented method.

  8. Effect of minimal shoes and slope on vertical and leg stiffness during running

    Directory of Open Access Journals (Sweden)

    Thibault Lussiana

    2015-06-01

    Conclusion: This study showed that kvert and kleg during running respond differently to change in footwear and/or slope. These two stiffness measures can hence provide a unique insight on the biomechanical adaptations of running under varying conditions and their respective quantification may assist in furthering our understanding of training, performance, and/or injury in this sport.

  9. The Effect of Climbing Ability and Slope Inclination on Vertical Foot Loading Using a Novel Force Sensor Instrumentation System

    Directory of Open Access Journals (Sweden)

    Baláš Jiří

    2014-12-01

    Full Text Available The aim of the study was to assess the effects of climbing ability and slope inclination on vertical loading both in terms the forces involved and physiological responses. Five novice and six intermediate female climbers completed a climbing route at three slope inclinations (85°, 90°, and 98°. The vertical loading during the climb was assessed by force-time integral using a Novel Pedar-X insole and physiological responses via oxygen uptake and heart rate. The novice climbers had a significantly lower (p < 0.05 vertical loading on foot holds and higher oxygen uptake and heart rate compared to intermediate climbers. A significant negative correlation was identified between the force-time integral and oxygen uptake (R = -0.72, and with heart rate (R = -0.64, respectively. The time-force integral decreased across the ascents with increasing slope inclination (p < 0.001. The results indicate that more advanced ability climbers make greater use of foot holds, with associated lowering in physiological response (oxygen uptake and heart rate across all slope inclinations.

  10. Effect of pouring temperature on cooling slope casting of semi-solid Al-Si-Mg alloy

    Institute of Scientific and Technical Information of China (English)

    Prosenjit Das; Sudip K. Samanta; Himadri Chattopadhyay; Pradip Dutta

    2012-01-01

    Present trend of semi-solid processing is directed towards rheocasting route which allows manufacturing of near-net-shape cast components directly from the prepared semi-solid slurry.Generation of globular equi-axed grains during solidification of rheocast components,compared to the columnar dendritic structure of conventional casting routes,facilitates the manufacturing of components with improved mechanical properties and structural integrity.In the present investigation,a cooling slope has been designed and indigenously fabricated to produce semi solid slurry of Al-Si-Mg (A356) alloy and successively cast in a metallic mould.The scope of the present work discusses about development of a numerical model to simulate the liquid metal flow through cooling slope using Eulerian two-phase flow approach and to investigate the effect of pouring temperature on cooling slope semi-solid slurry generation process.The two phases considered in the present model are liquid metal and air.Solid fraction evolution of the solidifying melt is tracked at different locations of the cooling slope,following Schiel's equation.The continuity equation,momentum equation and energy equation are solved considering thin wall boundary condition approach.During solidification of the liquid metal,a modified temperature recovery scheme has been employed taking care of the latent heat release and change of fraction of liquid.The results obtained from simulations are compared with experimental findings and good agreement has been found.

  11. SEASONAL REVERSE OF SEA SURFACE SLOPE IN THE NORTHERN YELLOW SEA AND ITS DYNAMIC RELATION WITH MONSOON EFFECTS

    Institute of Scientific and Technical Information of China (English)

    PU Shu-zhen; CHENG Jun; ZHANG Yi-jun; SHI Qiang

    2004-01-01

    Based on the monthly average sea level data from the tide gauge measurement(1999-2001),the seasonal variability of the sea level in the Northern and Middle Yellow Sea is studied to reveal that the sea surface height at all the tide gauges becomes higher in summer than that in winter.In addition,the sea surface height of the Northern Yellow Sea is higher than the one of the Middle Yellow Sea with a slope downward from the north to the south in summer,while it is lower with a reversed slope in winter.The seasonal reverse of the sea surface slope can be attributed to the monsoon effects i.e.the annual reverse of the monsoon direction and the annual variation of the monsoon rainfall.A set of equations are established in light of the dynamic principles to expound how the monsoon forcing and the sea surface slope generate a summer outflow and a winter inflow in the Yellow Sea.

  12. Hydrodynamic modeling of juvenile mussel dispersal in a large river: The potential effects of bed shear stress and other parameters

    Science.gov (United States)

    Daraio, J.A.; Weber, L.J.; Newton, T.J.

    2010-01-01

    Because unionid mussels have a parasitic larval stage, they are able to disperse upstream and downstream as larvae while attached to their host fish and with flow as juveniles after excystment from the host. Understanding unionid population ecology requires knowledge of the processes that affect juvenile dispersal prior to establishment. We examined presettlement (transport and dispersion with flow) and early postsettlement (bed shear stress) hydraulic processes as negative censoring mechanisms. Our approach was to model dispersal using particle tracking through a 3-dimensional flow field output from hydrodynamic models of a reach of the Upper Mississippi River. We tested the potential effects of bed shear stress (??b) at 5 flow rates on juvenile mussel dispersal and quantified the magnitude of these effects as a function of flow rate. We explored the reach-scale relationships of Froude number (Fr), water depth (H), local bed slope (S), and unit stream power (QS) with the likelihood of juvenile settling (??). We ran multiple dispersal simulations at each flow rate to estimate ??, the parameter of a Poisson distribution, from the number of juveniles settling in each grid cell, and calculated dispersal distances. Virtual juveniles that settled in areas of the river where b > critical shear stress (c) were resuspended in the flow and transported further downstream, so we ran simulations at 3 different conditions for ??c (??c = ??? no resuspension, 0.1, and 0.05 N/m2). Differences in virtual juvenile dispersal distance were significantly dependent upon c and flow rate, and effects of b on settling distribution were dependent upon c. Most simulations resulted in positive correlations between ?? and ??b, results suggesting that during early postsettlement, ??b might be the primary determinant of juvenile settling distribution. Negative correlations between ?? and ??b occurred in some simulations, a result suggesting that physical or biological presettlement processes

  13. An overview of the issues: physiological effects of bed rest and restricted physical activity

    Science.gov (United States)

    Convertino, V. A.; Bloomfield, S. A.; Greenleaf, J. E.

    1997-01-01

    Reduction of exercise capacity with confinement to bed rest is well recognized. Underlying physiological mechanisms include dramatic reductions in maximal stroke volume, cardiac output, and oxygen uptake. However, bed rest by itself does not appear to contribute to cardiac dysfunction. Increased muscle fatigue is associated with reduced muscle blood flow, red cell volume, capillarization and oxidative enzymes. Loss of muscle mass and bone density may be reflected by reduced muscle strength and higher risk for injury to bones and joints. The resultant deconditioning caused by bed rest can be independent of the primary disease and physically debilitating in patients who attempt to reambulate to normal active living and working. A challenge to clinicians and health care specialists has been the identification of appropriate and effective methods to restore physical capacity of patients during or after restricted physical activity associated with prolonged bed rest. The examination of physiological responses to bed rest deconditioning and exercise training in healthy subjects has provided significant information to develop effective rehabilitation treatments. The successful application of acute exercise to enhance orthostatic stability, daily endurance exercise to maintain aerobic capacity, or specific resistance exercises to maintain musculoskeletal integrity rather than the use of surgical, pharmacological, and other medical treatments for clinical conditions has been enhanced by investigation and understanding of underlying mechanisms that distinguish physical deconditioning from the disease. This symposium presents an overview of cardiovascular and musculoskeletal deconditioning associated with reduced physical work capacity following prolonged bed rest and exercise training regimens that have proven successful in ameliorating or reversing these adverse effects.

  14. Effect of flue gas recirculation on heat transfer in a supercritical circulating fluidized bed combustor

    Directory of Open Access Journals (Sweden)

    Błaszczuk Artur

    2015-09-01

    Full Text Available This paper focuses on assessment of the effect of flue gas recirculation (FGR on heat transfer behavior in 1296t/h supercritical coal-fired circulating fluidized bed (CFB combustor. The performance test in supercritical CFB combustor with capacity 966 MWth was performed with the low level of flue gas recirculation rate 6.9% into furnace chamber, for 80% unit load at the bed pressure of 7.7 kPa and the ratio of secondary air to the primary air SA/PA = 0.33. Heat transfer behavior in a supercritical CFB furnace between the active heat transfer surfaces (membrane wall and superheater and bed material has been analyzed for Geldart B particle with Sauter mean diameters of 0.219 and 0.246 mm. Bed material used in the heat transfer experiments had particle density of 2700 kg/m3. A mechanistic heat transfer model based on cluster renewal approach was used in this work. A heat transfer analysis of CFB combustion system with detailed consideration of bed-to-wall heat transfer coefficient distributions along furnace height is investigated. Heat transfer data for FGR test were compared with the data obtained for representative conditions without recycled flue gases back to the furnace through star-up burners.

  15. LONG TERM EFFECTS OF REHABILITATION MEASURES ON BED LOAD TRANSPORT AT THE SALZACH RIVER

    Institute of Scientific and Technical Information of China (English)

    Sven HARTMANN

    2001-01-01

    The river Salzach and its tributary Saalach as part of the border line between Germany and Austria represents a permanent water management problem since centuries. While in former times threats for the people mainly arose from severe flood events the present situation is characterized by significant ecological deficits. These were caused by a rectification of the river resulting in a concentration of the flow followed by erosion of the river bed. The situation got worse in the late 60s after construction of hydropower plants started upstream holding back nearly all bed load material. The degradation of the river bed in the downstream section of the Salzach is stated critical by the authorities in respect of the lack of sufficient gravel remaining on top of fine material. As erosion processes of fine sand and silt cannot be predicted accurately but will be probably much faster than those of the gravel bed measures are necessary to stabilize the river bottom to avoid major damages of the embankments and further degradation of the groundwater table. Different alternatives were investigated in a framework of a wide range of studies over the past years. One of the major tasks was to estimate the long term effects on bed load transport.

  16. Effect of flue gas recirculation on heat transfer in a supercritical circulating fluidized bed combustor

    Science.gov (United States)

    Błaszczuk, Artur

    2015-09-01

    This paper focuses on assessment of the effect of flue gas recirculation (FGR) on heat transfer behavior in 1296t/h supercritical coal-fired circulating fluidized bed (CFB) combustor. The performance test in supercritical CFB combustor with capacity 966 MWth was performed with the low level of flue gas recirculation rate 6.9% into furnace chamber, for 80% unit load at the bed pressure of 7.7 kPa and the ratio of secondary air to the primary air SA/PA = 0.33. Heat transfer behavior in a supercritical CFB furnace between the active heat transfer surfaces (membrane wall and superheater) and bed material has been analyzed for Geldart B particle with Sauter mean diameters of 0.219 and 0.246 mm. Bed material used in the heat transfer experiments had particle density of 2700 kg/m3. A mechanistic heat transfer model based on cluster renewal approach was used in this work. A heat transfer analysis of CFB combustion system with detailed consideration of bed-to-wall heat transfer coefficient distributions along furnace height is investigated. Heat transfer data for FGR test were compared with the data obtained for representative conditions without recycled flue gases back to the furnace through star-up burners.

  17. Effects of Soil Erosion on Ecohydrology of Constructed Slopes From Opencast Coal Mining in a Mediterranean-Continental Environment.

    Science.gov (United States)

    Moreno, M.; Nicolau, J.; Espigares, T.; Merino, L.

    2007-12-01

    Numerous works have revealed strong links between hydrological processes, soil moisture, and the structure and function of biological communities. Nevertheless, the influence of soil erosion on soil-water-plant interactions has been poorly documented, particularly on constructed slopes, wherein soil erosion has a key role for restoration success. The main objective of this work is to investigate the eco-hydrological implications of soil erosion on constructed slopes from the opencast coal mining in a Mediterranean-Continental environment: the Teruel coalfield (Spain). Water deficit is the main limiting factor for revegetation success in Mediterranean-Continental environments. Soil moisture in these artificial systems is controlled by feedback mechanisms between soil erosion and vegetation. Our hypothesis states that a major effect of soil erosion on plant communities deals with the increase of the climatic water deficit. Thus, the mechanisms involved are as follows: the crust formation, the reduction of soil superficial roughness and the efficient overland flow evacuation by means of rill network. The final result is a net reduction of water availability for plants through the increase of run-off and the decrease of infiltration and re- infiltration processes at slope scale. Moreover, the lack of vegetation development leads to increase run-off and soil erosion. This work has been carried out in five constructed slopes which were reclaimed with similar treatments and substrata, but differ in vegetation cover and erosion (from 0 up to 120 t/ha/year). These differences are mainly triggered by different amounts of run-on coming from external sources as mining tracks and banks. During 2005- 06 hydrological year, we monitored run-off and sediment yield as well as soil moisture and vegetation traits (cover, biomass, water potential) on these slopes. Our results reinforce the general hypothesis. In this way, on the least eroded slopes, biological control of hydrological

  18. Enhanced stability of steep channel beds to mass failure and debris flow initiation

    Science.gov (United States)

    Prancevic, J.; Lamb, M. P.; Ayoub, F.; Venditti, J. G.

    2015-12-01

    Debris flows dominate bedrock erosion and sediment transport in very steep mountain channels, and are often initiated from failure of channel-bed alluvium during storms. While several theoretical models exist to predict mass failures, few have been tested because observations of in-channel bed failures are extremely limited. To fill this gap in our understanding, we performed laboratory flume experiments to identify the conditions necessary to initiate bed failures in non-cohesive sediment of different sizes (D = 0.7 mm to 15 mm) on steep channel-bed slopes (S = 0.45 to 0.93) and in the presence of water flow. In beds composed of sand, failures occurred under sub-saturated conditions on steep bed slopes (S > 0.5) and under super-saturated conditions at lower slopes. In beds of gravel, however, failures occurred only under super-saturated conditions at all tested slopes, even those approaching the dry angle of repose. Consistent with theoretical models, mass failures under super-saturated conditions initiated along a failure plane approximately one grain-diameter below the bed surface, whereas the failure plane was located near the base of the bed under sub-saturated conditions. However, all experimental beds were more stable than predicted by 1-D infinite-slope stability models. In partially saturated sand, enhanced stability appears to result from suction stress. Enhanced stability in gravel may result from turbulent energy losses in pores or increased granular friction for failures that are shallow with respect to grain size. These grain-size dependent effects are not currently included in stability models for non-cohesive sediment, and they may help to explain better the timing and location of debris flow occurrence.

  19. Effect of H2O2 injection patterns on catalyst bed characteristics

    Science.gov (United States)

    Kang, Hongjae; Lee, Dahae; Kang, Shinjae; Kwon, Sejin

    2017-01-01

    The decomposition process of hydrogen peroxide can be applied to a bipropellant thruster, as well as to monopropellant thruster. To provide a framework for the optimal design of the injector and catalyst bed depending on a type of thruster, this research scrutinizes the effect of injection patterns of the propellant on the performance of the catalyst bed. A showerhead injector and impinging jet injector were tested with a 50 N monopropellant thruster. Manganese oxide/γ-alumina catalyst and manganese oxide/lanthanum-doped alumina catalyst were prepared and tested. The showerhead injector provided a fast response time, suitable for pulse mode operation. The impinging jet injector mitigated the performance instability and catalyst attrition that is favorable for large scale bipropellant thrusters. The design of a dual catalyst bed was conceptually proposed based on the data obtained from firing tests.

  20. The effect of biomass immobilization support material and bed porosity on hydrogen production in an upflow anaerobic packed-bed bioreactor.

    Science.gov (United States)

    Fernandes, B S; Saavedra, N K; Maintinguer, S I; Sette, L D; Oliveira, V M; Varesche, M B A; Zaiat, M

    2013-07-01

    The aim of this study was to investigate the effect of the support material used for biomass attachment and bed porosity on the potential generation of hydrogen gas in an anaerobic bioreactor treating low-strength wastewater. For this purpose, an upflow anaerobic packed-bed (UAPB) reactor fed with sucrose-based synthetic wastewater was used. Three reactors with various support materials (expanded clay, vegetal coal, and low-density polyethylene) were operated for hydraulic retention time (HRT) of 0.5 and 2 h. Based on the results obtained, three further reactors were operated with low-density polyethylene as a material support using various bed porosities (91, 75, and 50 %) for an HRT of 0.5 h. The UAPB reactor was found to be a feasible technology for hydrogen production, reaching a maximum substrate-based hydrogen yield of 7 mol H₂ mol(-1) sucrose for an HRT of 0.5 h. The type of support material used did not affect hydrogen production or the microbial population inside the reactor. Increasing the bed porosity to 91 % provided a continuous and cyclic production of hydrogen, whereas the lower bed porosities resulted in a reduced time of hydrogen production due to biomass accumulation, which resulted in a decreasing working volume.

  1. Fluid and salt supplementation effect on body hydration and electrolyte homeostasis during bed rest and ambulation

    Science.gov (United States)

    Zorbas, Yan G.; Kakurin, Vassily J.; Kuznetsov, Nikolai A.; Yarullin, Vladimir L.

    2002-06-01

    Bed rest (BR) induces significant urinary and blood electrolyte changes, but little is known about the effect of fluid and salt supplements (FSS) on catabolism, hydration and electrolytes. The aim was to measure the effect of FSS on catabolism, body hydration and electrolytes during BR. Studies were done during 7 days of a pre-bed rest period and during 30 days of a rigorous bed rest period. Thirty male athletes aged, 24.6±7.6 years were chosen as subjects. They were divided into three groups: unsupplemented ambulatory control subjects (UACS), unsupplemented bed rested subjects (UBRS) and supplemented bed rested subjects (SBRS). The UBRS and SBRS groups were kept under a rigorous bed rest regime for 30 days. The SBRS daily took 30 ml water per kg body weight and 0.1 sodium chloride per kg body weight. Plasma sodium (Na), potassium (K), calcium (Ca) and magnesium (Mg) levels, urinary Na, K, Ca and Mg excretion, plasma osmolality, plasma protein level, whole blood hemoglobin (Hb) and hematocrit (Hct) level increased significantly ( p≤0.05), while plasma volume (PV), body weight, body fat, peak oxygen uptake, food and fluid intake decreased significantly ( p≤0.05) in the UBRS group when compared with the SBRS and UACS groups. In contrast, plasma and urinary electrolytes, osmolality, protein level, whole blood Hct and Hb level decreased significantly ( p≤0.05), while PV, fluid intake, body weight and peak oxygen uptake increased significantly ( p≤0.05) in the SBRS group when compared with the UBRS group. The measured parameters did not change significantly in the UACS group when compared with their baseline control values. The data indicate that FSS stabilizes electrolytes and body hydration during BR, while BR alone induces significant changes in electrolytes and body hydration. We conclude that FSS may be used to prevent catabolism and normalize body hydration status and electrolyte values during BR.

  2. Effect of Temperature in Fluidized Bed Fast Pyrolysis of Biomass: Oil Quality Assessment in Test Units

    NARCIS (Netherlands)

    Westerhof, R.J.M.; Brilman, D.W.F.; Swaaij, van W.P.M.; Kersten, S.R.A.

    2010-01-01

    Pine wood was pyrolyzed in a 1 kg/h fluidized bed fast pyrolysis reactor that allows a residence time of pine wood particles up to 25 min. The reactor temperature was varied between 330 and 580 °C to study the effect on product yields and oil composition. Apart from the physical−chemical analysis, a

  3. Fluidized bed combustion chamber

    Energy Technology Data Exchange (ETDEWEB)

    Kullendorff, A.; Wikner, J.

    1985-03-25

    The chamber is confined in a pressure vessel. The lower part of the chamber has tilted parallel gutters up to the height of the fluidized bed. The slope of the gutter walls is 5 degrees-15 degrees and the top area of the gutters is 1.3 to 3 times larger than their bottom.

  4. Effect of Slope Plate Variable and Reheating on the Semi-Solid Structure of Ductile Cast Iron

    Institute of Scientific and Technical Information of China (English)

    M. Nili-Ahmadabadi; F. Pahlevani; P. Babaghorbani

    2008-01-01

    Semi-solid metal casting and forming is a promising production method for a wide range of metal alloys. In spite of many applications for semi-solid processed light alloys, few works have reported on the semi-solid processing of iron and steel. In this research, an inclined plate was used to change the dendritic structure of iron to globular. The effects of the length and slope of the plate on the casting structure were examined. The results show that the process effectively changes the dendritic structure to globular. A sloped plate angle of 7.5° and length of 560 mm with a cooling rate of 67 K·s-1 gave the optimum graphite nodu-larity and solid particle globularity. The results also show that the sloped plate more easily prevents inocu-lant fading since the total time processing is rather short. In addition the semi-solid ductile cast iron prepared using the inclined plate method was reheated to examine the effect of reheating conditions on the micro-structure and coarsening kinetics of the alloy. The solid fractions at different reheating temperatures and holding times were used to find the optimum reheating temperature range.

  5. The Effects of Long Duration Bed Rest on Functional Mobility and Balance: Relationship to Resting State Motor Cortex Connectivity

    Science.gov (United States)

    Erdeniz, B.; Koppelmans, V.; Bloomberg, J. J.; Kofman, I. S.; DeDios, Y. E.; Riascos-Castaneda, R. F.; Wood, S. J.; Mulavara, A. P.; Seidler, R. D.

    2014-01-01

    NASA offers researchers from a variety of backgrounds the opportunity to study bed rest as an experimental analog for space flight. Extended exposure to a head-down tilt position during long duration bed rest can resemble many of the effects of a low-gravity environment such as reduced sensory inputs, body unloading and increased cephalic fluid distribution. The aim of our study is to a) identify changes in brain function that occur with prolonged bed rest and characterize their recovery time course; b) assess whether and how these changes impact behavioral and neurocognitive performance. Thus far, we completed data collection from six participants that include task based and resting state fMRI. The data have been acquired through the bed rest facility located at the University of Texas Medical Branch (Galveston, TX). Subjects remained in bed with their heads tilted down 6 degrees below their feet for 70 consecutive days. Behavioral measures and neuroimaging assessments were obtained at seven time points: a) 7 and 12 days before bed rest; b) 7, 30, and 65 days during bed rest; and c) 7 and 12 days after bed rest. Functional connectivity magnetic resonance imaging (FcMRI) analysis was performed to assess the connectivity of motor cortex in and out of bed rest. We found a decrease in motor cortex connectivity with vestibular cortex and the cerebellum from pre bed rest to in bed rest. We also used a battery of behavioral measures including the functional mobility test and computerized dynamic posturography collected before and after bed rest. We will report the preliminary results of analyses relating brain and behavior changes. Furthermore, we will also report the preliminary results of a spatial working memory task and vestibular stimulation during in and out of bed rest.

  6. Effects of refraction on transmission spectra of gas giants: decrease of the Rayleigh scattering slope and breaking of retrieval degeneracies

    CERN Document Server

    Bétrémieux, Yan

    2015-01-01

    Detection of the signature of Rayleigh scattering in the transmission spectrum of an exoplanet is increasingly becoming the target of observational campaigns because the spectral slope of the Rayleigh continuum enables one to determine the scaleheight of its atmosphere in the absence of hazes. However, this is only true when one ignores the refractive effects of the exoplanet's atmosphere. I illustrate with a suite of simple isothermal clear Jovian H2-He atmosphere models with various abundances of water that refraction can decrease significantly the spectral slope of the Rayleigh continuum and that it becomes flat in the infrared. This mimics a surface, or an optically thick cloud deck, at much smaller pressures than one can probe in the non-refractive case. Although the relative impact of refraction on an exoplanet's transmission spectrum increases with decreasing atmospheric temperatures as well as increasing stellar temperature, it is still quite important from a retrieval's perspective even for a Jovian-...

  7. Effects of Slope and Aspect Variations on Satellite Surface Temperature Retrievals and Mesoscale Analysis in Mountainous Terrain.

    Science.gov (United States)

    Lipton, Alan E.

    1992-03-01

    Surface temperature retrieval in mountainous areas is complicated by the high variability of temperatures that can occur within a single satellite field of view. Temperatures depend in part on slope orientation relative to the sun, which can vary radically over very short distances. The surface temperature detected by a satellite is biased toward the temperatures of the sub-field-of-view terrain elements that most directly face the satellite. Numerical simulations were conducted to estimate the effects of satellite viewing geometry on surface temperature retrievals for a section of central Colorado. Surface temperatures were computed using a mesoscale model with a parameterization of subgrid variations in slope and aspect angles.The simulations indicate that the slope-aspect effect can lead to local surface temperature variations up to 30°C for autumn conditions in the Colorado mountains. For realistic satellite viewing conditions, these variations can give rise to biases in retrieved surface temperatures of about 3°C. Relative biases between retrievals from two satellites with different viewing angles can be over 6°C, which could lead to confusion when merging datasets. The bias computations were limited by the resolution of the available terrain height data (90 m). The results suggest that the biases would be significantly larger if the data resolution was fine enough to represent every detail of the real Colorado terrain or if retrievals were made in mountain areas that have a larger proportion of steep slopes than the Colorado Rockies. The computed bias gradients across the Colorado domain were not large enough to significantly alter the forcing of the diurnal upslope-downslope circulations, according to simulations in which surface temperature retrievals with view-dependent biases were assimilated into time-continuous analyses. View-dependent retrieval biases may be relevant to climatological analysts that rely on remotely sensed data, given that bias

  8. Analytical solution of coal-bed methane migration with slippage effects in hvpotonic reservoir

    Institute of Scientific and Technical Information of China (English)

    XIAO Xiao-chun; PAN Yi-shan; YU Li-yan; JIANG Chun-yu

    2011-01-01

    Using theoretical analysis, the single-phase gas seepage mathematical model influenced by slippage effects was established. The results show that the pressure of producing wells attenuates more violently than the wells without slippage effects. The decay rate of reservoir pressure is more violent as the Klinkenberg factor increases. The gas prediction output gradually increases as the Klinenberg factor increases when considering gas slippage effects. Through specific examples, analyzed the law of stope pore pressure and gas output forecast changing in a hypotonic reservoir with slippage effects. The results have great theoretical significance in the study of the law of coal-bed methane migration in hypotonic reservoirs and for the exploitation of coal-bed methane.

  9. Materials problems in fluidized-bed combustion systems: effect of process variables on in-bed corrosion. Interim report

    Energy Technology Data Exchange (ETDEWEB)

    Minchener, A.J.; Rogers, E.A.; LaNauze, R.D.

    1980-08-01

    The influence of operating conditions in a coal fired fluidized bed combustor on the rate of fireside corrosion of air cooled heat exchanger tubes, with metal temperatures in the range 540/sup 0/C to 900/sup 0/C, has been investigated. Four 250 hour tests were carried out on a 0.3 m square atmospheric pressure fluidized bed combustor operating with a fluidizing velocity of 0.9 ms/sup -1/, 10 to 20% excess air and bed temperatures of 850/sup 0/C and 900/sup 0/C. The feed coal was Illinois No. 6 which was used both with and without the addition of limestones to suppress the emission of sulfur oxides. A test without the addition of limestone showed very little corrosive attack of any metal components. Tests with the addition of limestone showed a range of corrosive attack. In general, where different alloy types were exposed at the same metal temperature, the iron based austenitic steels showed a better corrosion resistance than the nickel based alloys. This result strongly supports the model for the corrosion which has been developed as a result of the earlier investigations. This model postulates that local regions of low oxygen activity exist in the system, and, in the presence of calcium sulfate, these result in the generation of high local sulfur activities. The combination of low oxygen and high sulfur activities leads to sulfidation of sensitive alloys.

  10. Simulating run-up on steep slopes with operational Boussinesq models; capabilities, spurious effects and instabilities

    Directory of Open Access Journals (Sweden)

    F. Løvholt

    2013-06-01

    Full Text Available Tsunamis induced by rock slides plunging into fjords constitute a severe threat to local coastal communities. The rock slide impact may give rise to highly non-linear waves in the near field, and because the wave lengths are relatively short, frequency dispersion comes into play. Fjord systems are rugged with steep slopes, and modeling non-linear dispersive waves in this environment with simultaneous run-up is demanding. We have run an operational Boussinesq-type TVD (total variation diminishing model using different run-up formulations. Two different tests are considered, inundation on steep slopes and propagation in a trapezoidal channel. In addition, a set of Lagrangian models serves as reference models. Demanding test cases with solitary waves with amplitudes ranging from 0.1 to 0.5 were applied, and slopes were ranging from 10 to 50°. Different run-up formulations yielded clearly different accuracy and stability, and only some provided similar accuracy as the reference models. The test cases revealed that the model was prone to instabilities for large non-linearity and fine resolution. Some of the instabilities were linked with false breaking during the first positive inundation, which was not observed for the reference models. None of the models were able to handle the bore forming during drawdown, however. The instabilities are linked to short-crested undulations on the grid scale, and appear on fine resolution during inundation. As a consequence, convergence was not always obtained. It is reason to believe that the instability may be a general problem for Boussinesq models in fjords.

  11. Effect of work of adhesion on deep bed filtration process

    Science.gov (United States)

    Przekop, Rafał; Jackiewicz, Anna; WoŻniak, Michał; Gradoń, Leon

    2016-06-01

    Collection of aerosol particles in the particular steps of the technology of their production, and purification of the air at the workplace and atmospheric environment, requires the efficient method of separation of particulate matter from the carrier gas. There are many papers published in last few years in which the deposition of particles on fibrous collectors is considered, Most of them assume that collisions between particle and collector surface is 100% effective. In this work we study the influence of particles and fiber properties on the deposition efficiency. For the purpose of this work the lattice-Boltzmann model describes fluid dynamics, while the solid particle motion is modeled by the Brownian dynamics. The interactions between particles and surface are modelled using energy balanced oscillatory model. The work of adhesion was estimated using Atomic Force Microscopy.

  12. Hydrologic Effects of Clearcutting and Wildfire on Steep Granitic Slopes in Idaho

    Science.gov (United States)

    Megahan, Walter F.

    1983-06-01

    Many of the environmental impacts of logging and wildfire are caused by changes in the hydrologic response of slopes after disturbances. This study was conducted to evaluate changes in inflow, storage, and outflow for 3-year periods before and after clearcut logging and wildfire on two steep, granitic microwatersheds in Idaho. Clearcutting alone and clearcutting plus wildfire increased annual peak snow water equivalent and snowmelt rates an average of 41% and 30%, respectively. The greater volume and rate of snowmelt caused respective increases in the peak piezometric rise and in total piezometric storage, amounting to 47% and 27%. Accordingly, the total volume of subsurface flow intercepted by the roadcut was increased 96% and was accompanied by 27% greater peak flow rates. None of the above responses were detectable on an adjacent watershed that was burned by wildfire alone. Evapotranspiration was reduced on both watersheds after clearcutting or wildfire, as indicated by increases in the unsaturated soil water content at the end of the growing season amounting to 44 and 72%, respectively. Accelerated mass erosion on clearcut slopes, and accelerated surface and mass erosion on roads and in channels below roads, can result from such changes.

  13. Effectiveness of Mutual Learning Approach in the Academic Achievement of B.Ed Students in Learning Optional II English

    Science.gov (United States)

    Arulselvi, Evangelin

    2013-01-01

    The present study aims at finding out the effectiveness of Mutual learning approach over the conventional method in learning English optional II among B.Ed students. The randomized pre-test, post test, control group and experimental group design was employed. The B.Ed students of the same college formed the control and experimental groups. Each…

  14. Effect of Slope, Rainfall Intensity and Mulch on Erosion and Infiltration under Simulated Rain on Purple Soil of South-Western Sichuan Province, China

    Directory of Open Access Journals (Sweden)

    Muhammad Naeem Khan

    2016-11-01

    Full Text Available Purple soil is widely distributed in the hilly areas of the Sichuan basin, southwest China, and is highly susceptible to water erosion. The triggering of this process is related to slope, rainfall intensity and surface cover. Therefore, this study assesses the effects of different simulated rainfall intensities with different slopes on hydrological and erosional processes in un-mulched and mulched purple soils. Results show that the sediment and water losses increased with an increase of rainfall intensity and slope steepness. Generally, the slope contribution (Sc on water and sediment losses decreased with increasing rainfall intensity and slope steepness under both un-mulched and mulched soil. In un-mulched conditions, water losses were independent of slope steepness (Sc < 50% during the highest rainfall intensity. However, in mulched soil, the higher contributions of slope (Sc and rainfall (Rc were found for water and sediment losses, respectively, i.e., >50%, except during the increase in slope steepness from 15° to 25° under the highest rainfall intensity (120 mm·h−1. The effectiveness of mulch was more pronounced in reducing sediment losses (81%–100% compared with water losses (14%–100%. The conservation effectiveness of mulch both decreased and increased with slope steepness for water and sediment losses, respectively, under higher rainfall intensities. Water infiltration and recharge coefficient (RC decreased with an increase of slope steepness, while with an increase in rainfall intensity, the water infiltration and RC were increased and decreased, respectively, in both un-mulched and mulched soil. On the other hand, mulched soil maintained a significantly (α = 0.05 higher infiltration capacity and RC compared to that of the un-mulched soil.

  15. Effects of starvation and molting on the metabolic rate of the bed bug (Cimex lectularius L.).

    Science.gov (United States)

    DeVries, Zachary C; Kells, Stephen A; Appel, Arthur G

    2015-01-01

    The bed bug (Cimex lectularius L.) is a common hematophagous pest in the urban environment and is capable of surviving extended periods of starvation. However, the relationship between starvation and metabolism in bed bugs is not well understood. To better understand this relationship, we measured the metabolism of all life stages for >900 h after feeding (starvation) using closed-system respirometry. Measurements were made around molting for the immature life stages, which occurs only after a blood meal. In addition, both mated and unmated adults were measured. Starvation and molting had significant effects on the metabolism of the bed bug. Mass-specific metabolic rate (V(O2); mL g(-1) h(-1)) declined in a curvilinear fashion with the period of starvation for adults and with the postmolting period for immature bed bugs (used to standardize all immature life stages). A standard curve was developed to depict the generalized pattern of metabolic decline observed in all life stages that molted. Individual metabolic comparisons among life stages that molted revealed some differences in metabolic rate between unmated males and females. In addition, the mass scaling coefficient was found to decline with starvation time (postmolting time) for all life stages that molted. In most life stages, the ratio of V(CO2) to V(O2) (respiratory exchange ratio) declined over time, indicating a change in metabolic substrate with starvation. Finally, daily percent loss in body mass declined in a pattern similar to that of V(O2). The observed patterns in metabolic decline are evaluated in relation to the life history of bed bugs. In addition, the evolutionary development of these patterns is discussed. The metabolic pattern after feeding was also found to share several similarities with that of other ectothermic species.

  16. Use of wood-based materials in beef bedded manure packs: 2. Effect on odorous volatile organic compounds, odor activity value, , and nutrient concentrations.

    Science.gov (United States)

    Spiehs, Mindy J; Brown-Brandl, Tami M; Berry, Elaine D; Wells, James E; Parker, David B; Miller, Daniel N; Jaderborg, Jeffrey P; DiCostanzo, Alfred

    2014-07-01

    The objectives of this study were to determine the effects of three types of wood-based bedding materials (kiln-dried pine wood chips, dry cedar chips, and green cedar chips) and corn stover on the concentration of odorous volatile organic compounds (VOCs) and total in bedded pack material. Four bedded packs of each bedding material were maintained for two 42-d periods ( = 32; eight replicates/bedding material). Straight- and branched-chained fatty acids, aromatic compounds, and sulfide compounds were measured from the headspace above each bedded pack. Green cedar bedding had the highest concentration of odorous VOCs, and pine chip bedding had the lowest ( dry cedar, corn stover, and pine chip bedding. As the bedded packs aged, the concentration of odorous VOCs increased, particularly in the bedded packs containing green cedar chips and dry cedar chips. Total concentrations increased from Days 0 to 21 and then began to decline and were similar among all bedding materials ( < 0.10). Results of this study indicate that producers using a long-term bedded pack management in their facility may benefit from using pine chips because they do not appear to increase odor over time. Cedar-based bedding materials may be better suited for a scrape-and-haul system, where the bedded pack is removed after 1 or 2 wk. Total concentrations did not differ between any of the four bedding materials over time.

  17. Experimental Investigation of Effects of Vibration upon Elastic and Cohesive Properties of Beds of Wet Sand

    Directory of Open Access Journals (Sweden)

    S. Alsop

    1995-01-01

    Full Text Available The transmission of sinusoidal vibrations through beds of cohesive particulate solids was measured. Results were interpreted in terms of a critical state model to predict the elastic swelling constant k, and the cohesive stress C. Factorial experimental design was used to identify significant parameters. Factors that affect k include percent moisture, bulk density, sample size, sample shape, the presence of a supporting membrane, and loading order. Factors that affect C include percent moisture and particle size distribution. Factors affecting k were interpreted in terms of their effects upon bed structure and factors affecting C in terms of an equivalent pore water pressure due to capillary and liquid bridge effects. The critical state model was modified to incorporate general relationships between axial and radial strains.

  18. Effects of fluidized bed combustion residue on pecan seedling growth and nutrient content. [Carya illinoensis

    Energy Technology Data Exchange (ETDEWEB)

    Edwards, J.H.; White, A.W. Jr.; Bennett, O.L.

    1985-01-01

    Fluidized bed combustion residue from a calcitic limestone source (FBCRC), a by-product of scrubbing SO/sub 2/ from fossil fuel fired boilers using the FBC technique was evaluated as a source of calcium for pecan (Carya illinoensis (Wang.) K. Koch) seedlings. Fluidized bed combustion residue produced following injection of calcitic limestone into the combustion chamber was more effective in neutralizing soil acidity and increasing extractable soil Ca levels than agricultural calcitic limestone. The Ca concentration in the pecan leaves was increased linearly by Ca rates for both 12- and 24-week growth periods, but stem and petiole Ca concentration was increased linearly for the second 12-week growth period. Macronutrient concentrations were affected by Ca rates for both 12- and 24-week growth periods, but no effect was observed with Ca source. The primary difference was between the control and all other Ca rates.

  19. Elucidating the mechanical effects of pore water pressure increase on the stability of unsaturated soil slopes

    Science.gov (United States)

    Buscarnera, G.

    2012-12-01

    The increase of the pore water pressure due to rain infiltration can be a dominant component in the activation of slope failures. This paper shows an application of the theory of material stability to the triggering analysis of this important class of natural hazards. The goal is to identify the mechanisms through which the process of suction removal promotes the initiation of mechanical instabilities. The interplay between increase in pore water pressure, and failure mechanisms is investigated at material point level. In order to account for multiple failure mechanisms, the second-order work criterion is used and different stability indices are devised. The paper shows that the theory of material stability can assess the risk of shear failure and static liquefaction in both saturated and unsaturated contexts. It is shown that the combined use of an enhanced definition of second-order work for unsaturated porous media and a hydro-mechanical constitutive framework enables to retrieve bifurcation conditions for water-infiltration processes in unsaturated deposits. This finding discloses the importance of the coupling terms that incorporate the interaction between the solid skeleton and the pore fluids. As a consequence, these theoretical results suggest that some material properties that are not directly associated with the shearing resistance (e.g., the potential for wetting compaction) can play an important role in the initiation of slope failures. According to the proposed interpretation, the process of pore pressure increase can be understood as a trigger of uncontrolled strains, which at material point level are reflected by the onset of bifurcation conditions.

  20. Edge Effects Are Important in Supporting Beetle Biodiversity in a Gravel-Bed River Floodplain

    OpenAIRE

    2014-01-01

    Understanding complex, dynamic, and diverse ecosystems is essential for developing sound management and conservation strategies. Gravel-bed river floodplains are composed of an interlinked mosaic of aquatic and terrestrial habitats hosting a diverse, specialized, and endangered fauna. Therefore, they serve as excellent models to investigate the biodiversity of multiple ecotones and related edge effects. In this study, we investigated the abundance, composition, richness, and conservation stat...

  1. Solid conduction effects and design criteria in moving bed heat exchangers

    OpenAIRE

    Almendros-Ibáñez, J.A.; Soria-Verdugo, A.; Ruiz-Rivas, U.; Santana, D.

    2011-01-01

    Abstract This work presents a theoretical study of the energetic performance of a Moving Bed Heat Exchanger (MBHE), which consists on a ow of solid particles moving down that recovers heat from a gas ow percolating the solids in cross ow. In order to defne the solid conduction effects, two solutions for the MBHE energy equations have been studied: an analytical solution considering only convection heat transfer (and neglecting solid conduction) and a numerical solution with the sol...

  2. ANALYSIS METHODS ON STABILITY OF TALL AND BEDDIIG CREEP SLOPE

    Institute of Scientific and Technical Information of China (English)

    RUIYongqin; JIANGZhiming; LIUJinghui

    1995-01-01

    Based on the model of slope engineering geology,the creep and its failure mechanism of tall and bedding slope are deeply analyzed in this paper .The creep laws of weak intercalations are also discussed.The analysis om the stability of creep slope and the age forecasting of sliding slope have been conducted through mumerical simulations using Finite Element Method (FEM)and Dintimct Element Method(DEM).

  3. Effects of magnetic fields on improving mass transfer in flue gas desulfurization using a fluidized bed

    Science.gov (United States)

    Zhang, Qi; Gui, Keting; Wang, Xiaobo

    2016-02-01

    The effects of magnetic fields on improving the mass transfer in flue gas desulfurization using a fluidized bed are investigated in the paper. In this research, the magnetically fluidized bed (MFB) is used as the reactor in which ferromagnetic particles are fluidized with simulated flue gas under the influence of an external magnetic field. Lime slurry is continuously sprayed into the reactor. As a consequence, the desulfurization reaction and the slurry drying process take place simultaneously in the MFB. In this paper, the effects of ferromagnetic particles and external magnetic fields on the desulphurization efficiency are studied and compared with that of quartz particles as the fluidized particles. Experimental results show that the ferromagnetic particles not only act as a platform for lime slurry to precipitate on like quartz particles, but also take part in the desulfurization reaction. The results also show that the specific surface area of ferromagnetic particles after reaction is enlarged as the magnetic intensity increases, and the external magnetic field promotes the oxidation of S(IV), improving the mass transfer between sulphur and its sorbent. Hence, the efficiency of desulphurization under the effects of external magnetic fields is higher than that in general fluidized beds.

  4. Effect of Faulting on Ordovician Carbonate Buried-Hill Reservoir Beds in Hetianhe Gas Field,Tarim Basin

    Institute of Scientific and Technical Information of China (English)

    Lü Xiuxiang; Bai Zhongkai; Li Jianjiao; Wang Weiguang; Fu Hui; Wang Qinghua

    2008-01-01

    Ordovician carbonate buried-hill reservoir beds in the Hetianhe (和田河) gas field,located in the Mazhatage (玛扎塔格) structural belt on the southern margin of the Bachu (巴楚) faulted uplift,southwestern Tarim basin,were studied.Based on field survey,core and slice observation,the general characteristics of carbonate buried-hill reservoir beds and specifically Ordovician carbonate buried-hill reservoir beds in the Hetianhe gas field were discussed.The karst zone of the reservoir beds in Hetianhe gas field was divided into superficial karst zone,vertical infiltration karst zone,lower subsurface flow karst zone,and deep sluggish flow zone from top to bottom.The effects of faulting on Ordovician carbonate buried-hill reservoir beds in the Hetianhe gas field were obvious.The faulting intensified the karstification and increased the depth of denudation.Faulting and subsequent fracture growth modified the reservoir beds and improved the physical property and quality of the reservoir beds.Moreover,faulting enhanced the development of the dissolution holes and fractures and increased the thickness of the effective reservoir beds.Meanwhile,faulting made the high porosity-permeability carbonate belts,which created conditions for the hydrocarbon accumulation,develop near the fault zone.

  5. Energy identification method for dynamic failure mode of bedding rock slope with soft strata%含软弱夹层顺层岩质边坡动力破坏模式的能量判识方法研究

    Institute of Scientific and Technical Information of China (English)

    范刚; 张建经; 付晓; 王志佳; 田华

    2016-01-01

    基于希尔伯特–黄变换和边际谱理论,进行了含软弱夹层顺层岩质边坡的大型振动台试验,并利用试验结果对含软弱夹层顺层岩质边坡动力破坏模式的能量判识方法进行了研究,结果表明:边际谱峰值和特征频率的变化能清晰地表征边坡内部的震害损伤发展过程;地震作用下含软弱夹层顺层岩质边坡的损伤首先出现在坡肩位置,随着地震动强度的增大,震害损伤逐渐向低高程发展,最终边坡在坡体中上部相对高度0.56处沿软弱夹层顺层剪出,试验中坡面的位移监测结果表明坡体中上部位移出现陡增时刻晚于坡肩,边际谱分析结果与位移监测结果吻合较好;坡面附近的震害程度强于坡体内部;边坡中下部特征频率发生突变,表明坡体中下部为边坡动力响应的不连续带;含软弱夹层顺层岩质边坡的破坏形式主要表现为边坡后缘垂直的拉裂破坏和沿边坡中上部相对高度0.56处软弱夹层的剪切滑出破坏,边坡的破坏模式为拉裂-滑移-崩落式。本文提出的能量判识方法对识别边坡的破坏模式具有一定的指导意义。%Based on the Hilbert-Huang transformation and marginal spectrum theory, large scale shaking table tests on rock slope with soft strata are performed. The energy method for dynamic failure mode identification of bedding rock slope with soft strata is studied according to the test results. The research results in this work show that the peak value and characteristic frequency of marginal spectrum can represent the dynamic damage development process in the rock slope clearly. In the bedding rock slope with soft strata, the dynamic damage first occurs on the slope shoulder, and then the damage location moves to the lower elevation with the increase of input seismic wave amplitude, and finally, the slope is sheared out at the location of upper soft strata. In the displacement monitoring

  6. ElevationSlope_SLOPE1M2009

    Data.gov (United States)

    Vermont Center for Geographic Information — This metadata applies to the following collection area(s): Barre Montpelier 2009 1m and related SLOPE datasets. Created using ArcGIS "SLOPE" command to produce...

  7. ElevationSlope_SLOPE2M

    Data.gov (United States)

    Vermont Center for Geographic Information — This metadata applies to the following collection area(s): Bennington County 2012 2.0m and related SLOPE datasets. Created using ArcGIS "SLOPE" command to produce...

  8. ElevationSlope_SLOPE1M2005

    Data.gov (United States)

    Vermont Center for Geographic Information — This metadata applies to the following collection area(s): Essex County 2005 1m and related SLOPE datasets. Created using ArcGIS "SLOPE" command to produce change in...

  9. ElevationSlope_SLOPE1M2010

    Data.gov (United States)

    Vermont Center for Geographic Information — This metadata applies to the following collection area(s): Bennington Floodplain 2010 1m and related SLOPE datasets. Created using ArcGIS "SLOPE" command to produce...

  10. ElevationSlope_SLOPE1M2007

    Data.gov (United States)

    Vermont Center for Geographic Information — This metadata applies to the following collection area(s): Bennington Floodplain 2007 1m and related SLOPE datasets. Created using ArcGIS "SLOPE" command to produce...

  11. Effect of Soil Erosion on Soil Properties and Crop Yields on Slopes in the Sichuan Basin, China

    Institute of Scientific and Technical Information of China (English)

    SU Zheng-An; ZHANG Jian-Hui; NIE Xiao-Jun

    2010-01-01

    Roles of tillage erosion and water erosion in the development of within-field spatial variation of surface soil properties and soil degradation and their contributions to the reduction of crop yields were studied on three linear slopes in the Sichuan Basin,southwestern China.Tillage erosion was found to be the dominant erosion process at upper slope positions of each linear slope and on the whole short slope (20 m).On the long slope (110 m) and medium slope (40 m),watererosion was the dominant erosion process.Soil organic matter and soil nutrients in the tillage layer were significantly related to slope length and 137Cs inventories on the long slope;however,there was no significant correlation among themon the short slope,suggesting that water erosion lowered soil quality by transporting SOM and surface soil nutrients selectively from the upper to lower slope positions,while tillage erosion transported soil materials unselectively.On the medium slope,SOM,total N,and available N in the tillage layer were correlated with slope length and the other properties were distributed evenly on the slope,indicating that water erosion on this slope was still the dominant soil redistribution process.Similar patterns were found for the responses of grain yield,aboveground biomaas,and harvest index for slopes.These results indicated that tillage erosion was a major cause for soil degradation and grain yield reduction on the linear slopes because it resulted in displacement of the tillage layer soil required for maintaining soil quality and plant growth.

  12. Effects of gravel on infiltration, runoff, and sediment yield in landslide deposit slope in Wenchuan earthquake area, China.

    Science.gov (United States)

    Li, Tianyang; He, Binghui; Chen, Zhanpeng; Zhang, Yi; Liang, Chuan; Wang, Renxin

    2016-06-01

    Amounts of landslide deposits were triggered by the Wenchuan earthquake with magnitude 8.0 on May 12, 2008. The landslide deposits were composed of soil and rock fragments, which play important roles in hydrological and erosion processes in the steep slope of landslide deposits. The mixtures of soil and gravels are common in the top layers of landslide deposits, and its processes are obviously different with the soil without gravels. Based on the data of field investigation, a series of simulated scouring flow experiments with four proportion of gravel (0, 25, 33.3, and 50 %) and three scouring flow rates (4, 8, 12 L/min) under two steep slopes (67.5, 72.7 %) were conducted sequentially to know the effects of proportion of gravel on infiltration capacity, runoff generation, and sediment production in the steep slope of landslide deposit. Results indicated that gravel had promoted or reduced effects on infiltration capacity which could affect further the cumulative runoff volume and cumulative sediment mass increase or decrease. The cumulative infiltration volume in 25 % proportion of gravel was less than those in 0, 33.3, and 50 % proportion of gravel. The cumulative runoff volume was in an order of 25 > 0 > 33.3 > 50 % while cumulative sediment mass ranked as 25 > 33.3 > 0 > 50 % with different proportions of gravel. A significant power relationship was found between scouring time and cumulative runoff volume as well as cumulative sediment mass. The relationship between average soil and water loss rate and proportion of gravel was able to express by quadratic function, with a high degree of reliability. The results have important implications for soil and water conservation and modeling in landslide deposit but also provide useful information for the similar conditions.

  13. Effect of Wetting and Contamination of Granular Beds During Sphere Impact

    KAUST Repository

    Kouraytem, Nadia

    2013-03-01

    This thesis presents results from an experimental study of the impact of dense solid spheres onto granular beds. The overall aim is to further our understanding of the dynamical response of granular materials to impact. In order to do this, we will study both the initial penetration stages and peak acceleration exerted on the sphere by using high-speed imaging. Another critical part is to measure the penetration depth of the sphere and calculate the corresponding depth-averaged stopping force. Both of these main focal points will be assessed for not only dry, but wet and “contaminated” grains, whereby the granular bed will be comprised of two distinct size ranges of base grains. In doing so, we aim to broadly determine whether contaminated grains or wet grains are more effective at increasing the tensile strength of granular materials.

  14. Physiological Effects of Aquatic Exercise in Pregnant Women on Bed Rest.

    Science.gov (United States)

    Sechrist, Dawndra M; Tiongco, Cynthia Gorter; Whisner, Sandra M; Geddie, Matthew D

    2015-01-01

    This pilot study examined the effectiveness of an Aquatic Exercise Program (AEP) provided by an occupational therapist for pregnant women on hospitalized bed rest. Researchers conducted a retrospective analysis of medical records of hospitalized pregnant women comparing those who attended an AEP (n = 19) to a control group who received no AEP (n = 12). Statistical tests were used to assess evidence of differences in length of gestation as well as blood pressure and amniotic fluid index (AFI) at discharge. Women who received an AEP had increased AFI and length of gestation compared to the control group. This study supports the use of an AEP as an intervention for pregnant women on prescribed bed rest. Further research is recommended to validate these findings with a larger sample.

  15. Effects of sintered metal distributor on fluidization quality of the air dense medium fluidized bed

    Institute of Scientific and Technical Information of China (English)

    Yang Xuliang; Zhao Yuemin; Luo Zhenfu; Chen Zengqiang; Song Shulei

    2011-01-01

    Dry coal beneficiation using an air dense medium fluidized bed (ADMFB) requires the formation of a stable and uniform bed from the dense medium.Others have shown that the structure and geometric parameters of the air distributor have a significant influence on the experimentally observed fluidization quality.In this study we used a sintered metal distributor (SMD) in the ADMFB separator and study its effect on the fluidization quality.The results show that for the same open area ratio (OAR),a smaller aperture in the SMD will provide improved fluidization quality.If aperture size is held constant bigger open area ratios result in improved fluidization quality.And,the fluidization quality also improves when the pressure drop across the SMD increases.A model relating distributor pressure drop and the geometric parameters of the SMD is also proposed.

  16. Effect of Microwave on Fluidized Bed Drying of Beetroot (Beta vulgaris L.

    Directory of Open Access Journals (Sweden)

    Yashwant Kumar

    2016-07-01

    Full Text Available In the present work, an attempt has been made to study the effect of inlet air temperature and velocity on the drying characteristics of beetroot’s (Beta vulgaris L. pieces in microwave assisted fluidized bed drying (MAFBD system. The results were compared with samples of beetroot dried in a fluidized bed dryer (FBD at the same combination of temperatures and air velocities. The selected inlet air temperatures and inlet air velocities were 60°C, 67.50°C and 75°C and 9 m/s, 10.50 m/s and 12 m/s, respectively. Moisture content and outlet air humidity was measured at 5 minutes interval. The MAFBD method offered two to three times reduction in drying time as compared to the FBD method. It was also observed that the beetroot samples obtained from the MAFBD system had lower final moisture content than those obtained from the FBD system.

  17. Effects of different types of bedding materials on behavioral development in laboratory CD1 mice (Mus musculus).

    Science.gov (United States)

    Tanaka, Toyohito; Ogata, Akio; Inomata, Akiko; Nakae, Dai

    2014-10-01

    Male and female mice were housed in cages, containing different types of bedding materials (wood flakes or pulp chips), from 4 weeks of age in the F0 generation to 11 weeks of age in the F1 generation; selected reproductive and neurobehavioral parameters were measured in the F1 generation. There were no adverse effects of bedding materials on litter size, litter weight, or sex ratios at the time of birth. With regard to behavioral development parameters, bedding materials did not influence any variables (p > 0.05) in both sexes. Regarding exploratory behavior in the F1 generation, number of defecations significantly varied (p = 0.0203) with bedding materials in males at 3 weeks of age. The number of horizontal activities also significantly varied (p = 0.0342) with bedding materials in males at 8 weeks of age. Multiple-T water maze performance data indicated that the time required was significantly shortened across trials in pulp chips group than wood flakes group in males (p = 0.0211). Moreover, all spontaneous behavior variables in males significantly varied with bedding materials, particularly the average time of movement was significantly different (p = 0.0037) in distance between parallel lines of types of bedding materials in the F1 generation. The present study shows that bedding materials influence the neurobehavioral development in mice.

  18. Numerical study of cavitation and pinning effects due to gas injection through a bed of particles: application to a radial-flow moving-bed reactor

    Science.gov (United States)

    Vinay, Guillaume; Vasquez, Felaurys; Richard, Florence; Applied Mechanics Team

    2016-11-01

    In the petroleum and chemical industries, radial-flow moving-bed reactors are used to carry out chemical reactions such as catalytic reforming. Radial-flow reactors provide high capacity without increased pressure drop or greatly increased vessel dimensions. This is done by holding the catalyst in a basket forming an annular bed, and causing the gas to flow radially between the outer annulus and the central tube. Catalyst enter the top of the reactor, move through the vessel by gravity to the bottom where it is removed and then regenerated. Within the catalytic bed, the combined effects of particles motion and radial injection of the gas may lead to cavitation and pinning phenomenon that may clearly damage the reactor. We study both cavitation and pinning effects using an in-house numerical software, named PeliGRIFF (www.peligriff.com/), designed to simulate particulate flows at different scales; from the particle scale, where fluid/particle interactions are directly solved, to the particles suspension scale where the fluid/solid interactions are modeled. In the past, theoretical and experimental studies have already been conducted in order to understand the way cavitation and pinning occur. Here, we performed simulations involving a few thousands of particles aiming at reproducing experimental experiments. We will present comparisons between our numerical results and experimental results in terms of pressure drop, velocity, porosity.

  19. Slope and amplitude asymmetry effects on low frequency capacitively coupled carbon tetrafluoride plasmas

    Science.gov (United States)

    Bruneau, B.; Korolov, I.; Lafleur, T.; Gans, T.; O'Connell, D.; Greb, A.; Derzsi, A.; Donkó, Z.; Brandt, S.; Schüngel, E.; Schulze, J.; Johnson, E.; Booth, J.-P.

    2016-04-01

    We report investigations of capacitively coupled carbon tetrafluoride (CF4) plasmas excited with tailored voltage waveforms containing up to five harmonics of a base frequency of 5.5 MHz. The impact of both the slope asymmetry, and the amplitude asymmetry, of these waveforms on the discharge is examined by combining experiments with particle-in-cell simulations. For all conditions studied herein, the discharge is shown to operate in the drift-ambipolar mode, where a comparatively large electric field in the plasma bulk (outside the sheaths) is the main mechanism for electron power absorption leading to ionization. We show that both types of waveform asymmetries strongly influence the ion energy at the electrodes, with the particularity of having the highest ion flux on the electrode where the lowest ion energy is observed. Even at the comparatively high pressure (600 mTorr) and low fundamental frequency of 5.5 MHz used here, tailoring the voltage waveforms is shown to efficiently create an asymmetry of both the ion energy and the ion flux in geometrically symmetric reactors.

  20. Continuum viscoplastic simulation of a granular column collapse on large slopes: μ(I) rheology and lateral wall effects

    Science.gov (United States)

    Martin, N.; Ionescu, I. R.; Mangeney, A.; Bouchut, F.; Farin, M.

    2017-01-01

    We simulate here dry granular flows resulting from the collapse of granular columns on an inclined channel (up to 22°) and compare precisely the results with laboratory experiments. Incompressibility is assumed despite the dilatancy observed in the experiments (up to 10%). The 2-D model is based on the so-called μ (I ) rheology that induces a Drucker-Prager yield stress and a variable viscosity. A nonlinear Coulomb friction term, representing the friction on the lateral walls of the channel, is added to the model. We demonstrate that this term is crucial to accurately reproduce granular collapses on slopes ≳10°, whereas it remains of little effect on the horizontal slope. Quantitative comparison between the experimental and numerical changes with time of the thickness profiles and front velocity makes it possible to strongly constrain the rheology. In particular, we show that the use of a variable or a constant viscosity does not change significantly the results provided that these viscosities are of the same order. However, only a fine tuning of the constant viscosity (η =1 Pa s) makes it possible to predict the slow propagation phase observed experimentally at large slopes. Finally, we observed that small-scale instabilities develop when refining the mesh (also called ill-posed behavior, characterized in the work of Barker et al. ["Well-posed and ill-posed behaviour of the μ (I ) -rheology for granular flow," J. Fluid Mech. 779, 794-818 (2015)] and in the present work) associated with the mechanical model. The velocity field becomes stratified and the bands of high velocity gradient appear. These model instabilities are not avoided by using variable viscosity models such as the μ (I ) rheology. However we show that the velocity range, the static-flowing transition, and the thickness profiles are almost not affected by them.

  1. Effects of Tafel slope, exchange current density and electrode potential on the corrosion of steel in concrete

    Energy Technology Data Exchange (ETDEWEB)

    Ge, J.; Isgor, O.B. [Carleton University, Department of Civil and Environmental Engineering, Mackenzie Engineering Building, Ottawa, K1S 5B6 ON (Canada)

    2007-08-15

    A parametric study is carried out to investigate the effect of variations in anodic and cathodic Tafel slopes, exchange current densities and electrode potentials on the rate of steel corrosion in concrete. The main goal of this investigation is to identify the parameters that have significant influence on steel corrosion rate. Since there is a degree of uncertainty associated with the selection of these parameters, particularly during modelling exercises, it is intended that the results of this study will provide valuable information to engineers and researchers who simulate steel corrosion in concrete. To achieve this goal, the effect of a parameter on the corrosion rate of steel is studied while all other parameters are kept constant at a predefined base case. For each parameter, two extreme cases of anode-to-cathode ratio are studied. The investigation revealed that the variations in the anodic electrode potential have the greatest impact on the corrosion rate, followed by the variations in the cathodic Tafel slope. (Abstract Copyright [2007], Wiley Periodicals, Inc.)

  2. Insecticide-impregnated bed nets for malaria control: varying experiences from Ecuador, Colombia, and Peru concerning acceptability and effectiveness.

    Science.gov (United States)

    Kroeger, A; Mancheno, M; Alarcon, J; Pesse, K

    1995-10-01

    Between 1991 and 1994, an intervention program with permethrin- and lambdacyhalothrin-impregnated bed nets was carried out over a period of nine months in each of five endemic, malarious areas of Ecuador, Peru, and Colombia. This program was evaluated through household surveys, blood sampling, in-depth longitudinal studies, and entomologic analysis. Eighty-four communities (including approximately 35,000 individuals) were paired according to malaria incidence, size, and coverage with bed nets and then randomly allocated to intervention and control groups. The results showed that peoples' acceptance of the measure was related to their perception of an immediate protective effect against insects. The effectiveness of the bed nets, measured as a reduction of malaria incidence in intervention communities as against control communities, showed large variations between and within the study areas. The protective efficacy varied between 0% and 70% when looking only at the postintervention differences between intervention and control groups. The average protection was 40.8% when considering a four-month incidence of clinical malaria attacks and 28.3% when considering a two-week malaria incidence. Important factors for the success of the bed net program were insect susceptibility to pyrethroids, high coverage with impregnated bed nets, high malaria incidence, good community participation, high mosquito densities when people go to bed, and a high proportion of Plasmodium falciparum. In one area, where DDT spraying in the control communities was executed, the effectiveness of bed net impregnation was slightly better than that of spraying.

  3. Effect of 21 days of horizontal bed rest on behavioural thermoregulation.

    Science.gov (United States)

    Yogev, Daniel; Eiken, Ola; Pisot, Rado; Biolo, Gianni; di Prampero, Pietro; Narici, Marco; Mekjavic, Igor B

    2010-01-01

    The present study investigated the effect of 21 days of horizontal bed rest on cutaneous cold and warm sensitivity, and on behavioural temperature regulation. Healthy male subjects (N = 10) were accommodated in a hospital ward for the duration of the study and were under 24-h medical care. All activities (eating, drinking, hygiene, etc.) were conducted in the horizontal position. On the 1st and 22nd day of bed rest, cutaneous temperature sensitivity was tested by applying cold and warm stimuli of different magnitudes to the volar region of the forearm via a Peltier element thermode. Behavioural thermoregulation was assessed by having the subjects regulate the temperature of the water within a water-perfused suit (T (wps)) they were wearing. A control unit established a sinusoidal change in T (wps), such that it varied from 27 to 42 degrees C. The subjects could alter the direction of the change of T (wps), when they perceived it as thermally uncomfortable. The magnitude of the oscillations towards the end of the trial was assumed to represent the upper and lower boundaries of the thermal comfort zone. The cutaneous threshold for detecting cold stimulus decreased (P wps). We conclude that although cold sensitivity increased after bed rest, it was not of sufficient magnitude to cause any alteration in behavioural thermoregulatory responses.

  4. A study on the effects of operational parameters on bed-to-wall heat transfer

    Energy Technology Data Exchange (ETDEWEB)

    Gungor, A. [Nigde University, Nigde (Turkey). Dept. of Mechanical Engineering

    2009-08-15

    In this study the effects of operational parameters on bed-to-wall heat transfer in CFBs are investigated such as solids volume fraction, particle diameter, suspension density, solid circulation rate. Based on a previously developed 2D CFB model, a modified cluster renewal model is used in this investigation. The model uses the particle-based approach (PBA) and integrates the hydrodynamics and combustion aspects. The study is also validated with experimental data. As a result of this study, it is observed that the bed-to-wall heat transfer coefficients are strongly dependent on particle diameter and solids concentration at the riser wall. The smaller particles result in higher heat transfer coefficients than larger particles for the same solids volume fraction values. The heat transfer coefficient increases with suspension density. However, at a constant suspension density, the superficial velocity does not have a significant influence on the heat transfer coefficient. PBA is satisfactorily adapted to cluster renewal model so that to define the bed-to-wall heat transfer mechanisms for the upper zone.

  5. The effect of coal-bed methane water on spearmint and peppermint.

    Science.gov (United States)

    Zheljazkov, Valtcho D; Cantrell, Charles L; Astatkie, Tess; Schlegel, Vicki; Jeliazkova, Ekaterina; Lowe, Derek

    2013-11-01

    Coal bed methane is extracted from underground coal seams that are flooded with water. To reduce the pressure and to release the methane, the water needs to be pumped out. The resulting waste water is known as coal bed methane water (CBMW). Major concerns with the use of CBMW are its high concentrations of S, Na, dissolved Ca, Mg, SO, and bicarbonate (HCO). Irrigation water is a scarce resource in most of the western states. The objective of this study was to evaluate the effect of various amounts of CBMW on the growth, essential oil content, composition, and antioxidant activity of spearmint ( L.) and peppermint ( L.) crops that were irrigated with the water. These two crops are grown in some western states and are potential specialty crops to Wyoming farmers. The irrigation treatments were 0% CBMW (tap water only), 25% CBMW (25% CBMW plus 75% tap water), 50% CBMW (50% CBMW and 50% tap water), 75% CBMW (75% CBMW plus 25% tap water), and 100% CBMW. Analyses of the data revealed that the CBMW treatments did not affect the antioxidant capacity of spearmint or peppermint oil (242 and 377 μmol L Trolox g, respectively) or their major oil constituents (carvone or menthol). Coal bed methane water at 100% increased total phenols and total flavonoids in spearmint but not in peppermint. Coal bed methane water also affected oil content in peppermint but not in spearmint. Spearmint and peppermint could be watered with CBMW at 50% without suppression of fresh herbage yields. However, CBMW at 75 and 100% reduced fresh herbage yields of both crops and oil yields of peppermint relative to the control.

  6. Exercise Effects on the Brain and Sensorimotor Function in Bed Rest

    Science.gov (United States)

    Koppelmans, V.; Cassady, K.; De Dios, Y. E.; Szecsy, D.; Gadd, N.; Wood, S. J.; Reuter-Lorenz, R. A.; Kofman, I.; Bloomberg, J. J.; Mulavara, A. P.; Ploutz-Snyder, L.; Seidler, R. D.

    2016-01-01

    Long duration spaceflight microgravity results in cephalad fluid shifts and deficits in posture control and locomotion. Effects of microgravity on sensorimotor function have been investigated on Earth using head down tilt bed rest (HDBR). HDBR serves as a spaceflight analogue because it mimics microgravity in body unloading and bodily fluid shifts. Preliminary results from our prior 70 days HDBR studies showed that HDBR is associated with focal gray matter (GM) changes and gait and balance deficits, as well as changes in brain functional connectivity. In consideration of the health and performance of crewmembers we investigated whether exercise reduces the effects of HDBR on GM, functional connectivity, and motor performance. Numerous studies have shown beneficial effects of exercise on brain health. We therefore hypothesized that an exercise intervention during HDBR could potentially mitigate the effects of HDBR on the central nervous system. Eighteen subjects were assessed before (12 and 7 days), during (7, 30, and 70 days) and after (8 and 12 days) 70 days of 6-degrees HDBR at the NASA HDBR facility in UTMB, Galveston, TX, US. Each subject was randomly assigned to a control group or one of two exercise groups. Exercise consisted of daily supine exercise which started 20 days before the start of HDBR. The exercise subjects participated either in regular aerobic and resistance exercise (e.g. squat, heel raise, leg press, cycling and treadmill running), or aerobic and resistance exercise using a flywheel apparatus (rowing). Aerobic and resistance exercise intensity in both groups was similar, which is why we collapsed the two exercise groups for the current experiment. During each time point T1-weighted MRI scans and resting state functional connectivity scans were obtained using a 3T Siemens scanner. Focal changes over time in GM density were assessed using voxel based morphometry (VBM8) under SPM. Changes in resting state functional connectivity was assessed

  7. Investigation of effective thermal conductivity for pebble beds by one-way coupled CFD-DEM method for CFETR WCCB

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Lei [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, Anhui 230031 (China); University of Science and Technology of China, Hefei, Anhui 230027 (China); Chen, Youhua [University of Science and Technology of China, Hefei, Anhui 230027 (China); Huang, Kai [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, Anhui 230031 (China); Liu, Songlin, E-mail: slliu@ipp.ac.cn [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, Anhui 230031 (China); University of Science and Technology of China, Hefei, Anhui 230027 (China)

    2016-05-15

    Highlights: • A CFD-DEM coupled numerical model is built based on the prototypical blanket pebble bed. • The numerical model can be applied to simulate heat transfer of a pebble bed and estimate effective thermal conductivity. • The numerical model agrees well with the theoretical SZB model. • Effective thermal conductivity of pebble beds for WCCB is estimated by the current model. - Abstract: The mono-sized beryllium pebble bed and the multi-sized Li{sub 2}TiO{sub 3}/Be{sub 12}Ti mixed pebble bed are the main schemes for the Water-cooled ceramic breeder blanket (WCCB) of China Fusion Engineering Test Reactor (CFETR). And the effective thermal conductivity (k{sub eff}) of the pebble beds is important to characterize the thermal performance of WCCB. In this study, a one-way coupled CFD-DEM method was employed to simulate heat transfer and estimate k{sub eff}. The geometric topology of a prototypical blanket pebble bed was produced by the discrete element method (DEM). Based on the geometric topology, the temperature distribution and the k{sub eff} were obtained by the computational fluid dynamics (CFD) analysis. The current numerical model presented a good performance to calculate k{sub eff} of the beryllium pebble bed, and according to the modeling of the Li{sub 2}TiO{sub 3}/Be{sub 12}Ti mixed pebble bed, k{sub eff} was estimated with values ranged between 2.0 and 4.0 W/(m∙K).

  8. Effects of Bahia Grass Cover and Mulch on Runoff and Sediment Yield of Sloping Red Soil in Southern China

    Institute of Scientific and Technical Information of China (English)

    LI Xin-Hu; ZHANG Zhan-Yu; YANG Jie; ZHANG Guo-Hua; WANG Bin

    2011-01-01

    Rainfall, runoff (surface runoff, interflow and groundwater runoff) and soil loss from 5 m × 15 m plots were recorded for 5 years (2001-2005) in an experiment with three treatments (cover, mulch and bare ground) on sloping red soil in southern China. Surface runoff and erosion from the Bahia grass (Paspalum notatum Flugge) cover plot (A) and mulch plot (B) during the 5 years were low,despite the occurrence of potentially erosive rains. In contrast, the bare plot (C) had both the highest surface runoff coefficient and the highest sediment yield. There were significant differences in interflow and surface runoff and no significant difference in groundwater runoff among plots. The runoff coefficients and duration of interflow and groundwater runoff were in the order plot B > plot A > plot C. Effects of Bahia grass cover were excellent, indicating that the use of Bahia grass cover can be a simple and feasible practice for soil and water conservation on sloping red soil in the region.

  9. Tailored Voltage Waveforms in an SF6 /O2 discharge: slope asymmetry and its effect on surface nanotexturing of silicon

    Science.gov (United States)

    Fischer, G.; Drahi, E.; Poulain, G.; Bruneau, B.; Johnson, E. V.

    2016-09-01

    The nanotexturing of the surface of a crystalline silicon (c-Si) wafer for improved photovoltaic performance can be achieved through the use of a SF6 /O2 capacitively coupled reactive ion etching plasma. In this study, we attempt to modify the texturing conditions by taking advantage of slope asymmetries of Tailored Voltage Waveform (TVW) excitation. We show that TVW shapes resembling ``sawtooths'', presenting a large slope asymmetry, induce high ionization asymmetries in the discharge, and that the dominance of this effect strongly depends on both gas mixture and pressure. These asymmetries have been previously observed in other electronegative gas and are due to differing plasma sheath dynamics at powered and grounded electrode in a discharge operating in drift-ambipolar mode. The texturing of c-Si in SF6 /O2 occurs through competing mechanisms, including etching by fluorine radicals and in-situ deposition of micro-masking species. The relative fluxes of etching and passivating species are expected to be strongly varied due to the plasma asymmetry. Morphological and optical characterization of textured c-Si surfaces will give more insight into both the plasma properties and the mechanisms involved in dry nanotexturing. This project has been supported by the French Government in the frame of the program of investment for the future (Programme d'Investissement d'Avenir - ANR-IEED-002-01).

  10. Reinforcement mechanism of slope stability method with no cutting trees

    OpenAIRE

    Yuki, Chikata; Harushige, KUSUMI; 楠見, 晴重; Katsumi, TERAOKA

    2008-01-01

    The study in this paper is the slope stability. Although many slopes are prone to collapse, countermeasures against slop failures have not been progressed yet in Japan. Most slope protection methods were to cover shotcrete on the slope in 1960’s. However, the slope covered shotcrete have been deteriorating. Therefore, the slope failures frequently occur due to the natural disaster such as heavy rainfall and earthquake. It is important to develop an effective slope stability method. Moreover, ...

  11. Coal-Bed Methane Water Effects on Dill and Its Essential Oils.

    Science.gov (United States)

    Poudyal, Shital; Zheljazkov, Valtcho D; Cantrell, Charles L; Kelleners, Thijs

    2016-03-01

    Pumping water from coal seams decreases the pressure in the seam and in turn releases trapped methane; this is the most common and economic method of methane extraction. The water that is pumped out is known as "coal-bed methane water" (CBMW), which is high in sodium and other salts. In the past 25 yr, the United States has seen a 16-fold increase in the production of coal bed methane gas, and trillions of cubic meters are yet to be extracted. There is no sustainable disposal method for CBMW, and there are very few studies investigating the effects of this water on plants and their secondary metabolites and on soil properties. This study was conducted to determine the effects of CBMW on soil chemical properties and on the biomass and essential oil yield and composition of dill ( L.). This crop was grown in a greenhouse and was subjected to different levels of CBMW treatment: tap water only; 25% CBMW, 75% tap water; 50% CBMW, 50% tap water; 75% CBMW, 25% tap water; and 100% CBMW. The major dill oil constituents, limonene and α-phellandrene, were not affected by the treatments; however, the concentration of dill ether increased with increasing CBMW levels, whereas the concentration of carvone decreased. In soil, sodium level significantly increased with increasing level of treatment, but pH and cation exchange capacity were not much affected. Coal bed methane water could be used for irrigation of dill for one growing season, but longer-term studies may be needed to clarify the long-term effects on soil and plant.

  12. Effect of cohesion on granular-fluid flows in spouted beds: PIV measurement and DEM simulations

    Science.gov (United States)

    Zhu, Runru; LI, Shuiqing; Yao, Qiang

    2013-06-01

    In contrast to wet granular flows, the effect of cohesion on complex granular-fluid flows is intriguing but much challenging. The liquid bridges, forming between binary particles with the addition of a small amount of liquids, might significantly change the granular-fluid system due to both cohesion and lubrication effects. In this paper, a spouted bed, among various fluidization technologies, is particularly selected as a prototypical system for studying granular-fluid flows, since it can provide a quasi-steady flow pattern of granular particles, i.e., a core of upward granular-fluid flow called the "spout" and a surrounding region of downward quasi-static granular flow called the "annulus". Firstly, using self-developed particle image velocimetery (PIV) technique, the effects of cohesion on the spout-annulus interface (namely the spout width) and on the particle velocity profiles in distinct zones are examined. Further, the discrete element method (DEM), by incorporating liquid bridge adhesion into soft-sphere model, is established and used to predict the microdynamic behavior of particles in spouted beds. Finally, based on both experiments and DEM validation, the effects on the granular patterns in these two zones are comparatively discussed.

  13. Capacity and Utilization in Health Care: The Effect of Empty Beds on Neonatal Intensive Care Admission.

    Science.gov (United States)

    Freedman, Seth

    2016-05-01

    Because geographic variation in medical care utilization is jointly determined by both supply and demand, it is difficult to empirically estimate whether capacity itself has a causal impact on utilization in health care. In this paper, I exploit short-term variation in Neonatal Intensive Care Unit (NICU) capacity that is unlikely to be correlated with unobserved demand determinants. I find that available NICU beds have little to no effect on NICU utilization for the sickest infants, but do increase utilization for those in the range of birth weights where admission decisions are likely to be more discretionary.

  14. Effect of Mulch Surface Color on Root-knot of Tomato Grown in Simulated Planting Beds

    OpenAIRE

    Fortnum, B. A.; Kasperbauer, M. J.; Decoteau, D. R.

    2000-01-01

    The effect of different-colored polyethylene mulches on quantity and spectra of reflected light, plant morphology, and root-knot disease was studied in tomato (Lycopersicon esculentum) grown in simulated planting beds. Tomato plants were inoculated with Meloidogyne incognita at initial populations (Pi) of 0, 1,000, 10,000, or 50,000 eggs/plant, and grown in a greenhouse for 50 days over white, red, or black mulch. Soil temperature was kept constant among the mulch treatments by placing an ins...

  15. The origin ofhigh hydraulic resistance for filter cakes ofdef ormable particles: cell-bed deformation or surface-layer effect?

    OpenAIRE

    Meireles, Martine; Molle, C.; Clifton, Michaël; Aimar, Pierre

    2004-01-01

    This study reports a numerical approach for modeling the hydraulic resistance ofa filter cake ofdef ormable cells. First, a mechanical and osmotic model that describes the volume fraction ofsolids in a bed ofyeast cells as a function ofthe compressive pressure it experiences is presented. The effects ofpressure on the compressibility ofyeast cells beds were further investigated both by filtration experiments and by centrifugal experiments based on the multiple speed equilibrium sediment he...

  16. Effect of Wavelike Sloping Plate Rheocasting on Microstructures of Hypereutectic Al-18 pct Si-5 pct Fe Alloys

    Science.gov (United States)

    Guan, Ren-Guo; Zhao, Zhan-Yong; Lee, Chong Soo; Zhang, Qiu-Sheng; Liu, Chun-Ming

    2012-04-01

    To refine and spheroidize the microstructures of hypereutectic Al-Si-Fe alloys, a novel method of wavelike sloping plate (WSP) rheocasting was proposed, and the effect of the WSP rheocasting on the microstructures of hypereutectic Al-18 pct Si-5 pct Fe alloys was investigated. The results reveal that the morphologies of the primary Si crystal, the Al18Si10Fe5, and the Al8Si2Fe phases can be improved by the WSP rheocasting, and various phases tend to be refined and spheroidized with the decrease of the casting temperature. The alloy ingots with excellent microstructures can be obtained when the casting temperature is between 943 K and 953 K (670 °C and 680 °C). During the WSP rheocasting, the crystal nucleus multiplication, inhibited grain growth, and dendrite break-up take place simultaneously, which leads to grain refinement of the alloys.

  17. Modeling of spatial lag in bed-load transport processes and its effect on dune morphology

    NARCIS (Netherlands)

    Duin, van O.J.M.; Hulscher, S.J.M.H.; Ribberink, J.S.; Dohmen-Janssen, C.M.

    2016-01-01

    In the present study, two bed-load transport models are introduced in an existing idealized dune model. These allow for the modeling of the spatial lag between the sediment transport rate and bed shear stress along dune surfaces. This lag is an important factor in determining transitions between bed

  18. 2-D SIMULATION OF CHANNEL FLOWS WITH MOVEABLE BED

    Institute of Scientific and Technical Information of China (English)

    Wilhelm BECHTELER; Davood FARSHI

    2001-01-01

    This paper presents some preliminary results of 2-D numerical simulation of open channel flow with moveable bed. The unsteady two dimensional channel flow and sediment transport are simulated by solving shallow water equations and sediment continuity equation in conservation form based on unstructured finite volume method. Redefining longitudinal and transverse slopes of the bed is implemented in order to consider them in the bedload equation. A simple modeling treatment dealing with secondary flow effect on sediment movement is also discussed. Finally, two examples of numerical simulation are presented.

  19. Effect of fuel properties on the bottom ash generation rate by a laboratory fluidized bed combustor

    Energy Technology Data Exchange (ETDEWEB)

    Rozelle, P.L.; Pisupati, S.V.; Scaroni, A.W. [Penn State University, University Park, PA (United States). Dept. of Energy & Geoenvironmental Engineering

    2007-06-15

    The range of fuels that can be accommodated by an FBC boiler system is affected by the ability of the fuel, sorbent, and ash-handling equipment to move the required solids through the boiler. Of specific interest is the bottom ash handling equipment, which must have sufficient capacity to remove ash from the system in order to maintain a constant bed inventory level, and must have sufficient capability to cool the ash well below the bed temperature. Quantification of a fuel's bottom ash removal requirements can be useful for plant design. The effect of fuel properties on the rate of bottom ash production in a laboratory FBC test system was examined. The work used coal products ranging in ash content from 20 to 40+ wt. %. The system's classification of solids by particle size into flyash and bottom ash was characterized using a partition curve. Fuel fractions in the size range characteristic of bottom ash were further analyzed for distributions of ash content with respect to specific gravity, using float sink tests. The fuel fractions were then ashed in a fixed bed. In each case, the highest ash content fraction produced ash with the coarsest size consist (characteristic of bottom ash). The lower ash content fractions were found to produce ash in the size range characteristic of flyash, suggesting that the high ash content fractions were largely responsible for the production of bottom ash. The contributions of the specific gravity fractions to the composite ash in the fuels were quantified. The fuels were fired in the laboratory test system. Fuels with higher amounts of high specific gravity particles, in the size ranges characteristic of bottom ash, were found to produce more bottom ash, indicating the potential utility of float sink methods in the prediction of bottom ash removal requirements.

  20. Effects of herbivorous birds on intertidal seagrass beds in the northern Wadden Sea

    Science.gov (United States)

    Nacken, M.; Reise, K.

    2000-07-01

    During autumn migration (September to December), brent geese (Branta b. bernicla) and wigeon (Anas penelope) feed on the seagrass Zostera noltii in the nearshore, upper tidal zone leeward of the island of Sylt (eastern North Sea). To graze on leaves and shoots above the sediment and on rhizomes and roots below, these birds reworked the entire upper 1 cm layer of sediment eight times within this 3-month period. In addition, brent geese excavated pits 3-10 cm deep by trampling in order to feed on below-ground phytomass. About 12% of the seagrass beds became pitted to an average depth of 4.5 cm. Using net exclosures, it was estimated that birds removed 34 g dry weight m-2 of above-ground and 28 g of below-ground phytomass. This corresponds to 45% of the phytomass in September. Of the overall loss of phytomass from September to December, 63% was caused by birds. Roughly half of the leaves fell off anyway until December and the other half were taken by the birds. Below the ground, phytomass remained almost constant where birds were excluded, while with birds phytomass of rhizomes and roots was halved. In spite of this strong effect, in the next vegetation period the blade density was lower at former exclosure sites compared to the ambient seagrass bed. The underlying process seems to be a self-inhibition of dense overwintering seagrass by mud accretion. Assuming our experimental results can be scaled up to the entire seagrass bed, we hypothesize that in the sheltered upper intertidal zone, seasonal erosion caused by herbivorous geese and ducks is necessary for the persistence of Z. noltii.

  1. Standard metabolic rate of the bed bug, Cimex lectularius: effects of temperature, mass, and life stage.

    Science.gov (United States)

    Devries, Zachary C; Kells, Stephen A; Appel, Arthur G

    2013-11-01

    Metabolic rates provide important information about the biology of organisms. For ectothermic species such as insects, factors such as temperature and mass heavily influence metabolism, but these effects differ considerably between species. In this study we examined the standard metabolic rate of the bed bug, Cimex lectularius L. We used closed system respirometry and measured both O2 consumption and CO2 production across a range of temperatures (10, 20, 25, 30, 35°C) and life stages, while also accounting for activity. Temperature had a stronger effect on the mass specific .VO2 (mlg(-1)h(-1)) of mated males (Q10=3.29), mated females (Q10=3.19), unmated males (Q10=3.09), and nymphs that hatched (first instars, Q10=3.05) than on unmated females (Q10=2.77) and nymphs that molted (second through fifth instars, Q10=2.78). First instars had significantly lower respiratory quotients (RQ) than all other life stages. RQ of all stages was not affected by temperature. .VO2 (mlh(-1)) scaled more with mass than values previously reported for other arthropods or that would be predicted by the 3/4-power law. The results are used to understand the biology and ecology of the bed bug.

  2. Talus slope development: an integrated concept based on the Eastern Alps.

    Science.gov (United States)

    Sanders, D.; Ostermann, M.

    2009-04-01

    Talus slopes are deposystems that accumulate in onlap onto the area of sediment provenance, that is, rock cliffs. 'Talus slope - rock cliff ensembles' are subject to strong internal feedback due to the direct interplay of slope accumulation with cliff degradation. Our field observations in numerous Quaternary talus-slope successions indicate an overall predictable relation between talus slope maturity, depositional geometry, and sedimentary facies: After exposure of rock cliffs by deglaciation or rocksliding, a low-dipping immature talus (dominated by debris flows and/or by rockfalls) or a rock glacier initially accumulates. Upon progressive aggradation and steepening of the proximal slope segment, prevalent processes of deposition change to grain flows and 'sorted rockfalls' in the steep-dipping (30-35°) proximal slope segment, while deposits of debris flows, ephemeral fluid flows, and rare large rockfalls prevail on the distal, lower-dipping slope segment. In successions of mature talus slopes, the proximal slope package overlies the lower-dipping, distal slope deposits along a narrow 'downlap interval'. The downlap interval is characterized by a marked upslope steepening of bedding surfaces over a short vertical and lateral distance. Immediately after cliff exposure by deglaciation or rocksliding, talus can aggrade at rates of up to a few tens of meters per 1000 years; initially high accumulation rates, however, decrease rapidly with buildup of slope and consequent burial of the rock cliff. On present carbonate-lithic talus slopes of the Eastern Alps the prevalent processes of sediment transport, final deposition, and deposit overprint in many cases change over lateral distances of a few tens to a few hundreds of meters; this gives rise to different types of talus slopes. Whereas glacial-interglacial cycles determine presence/absence of talus, as well as the altitude range of effective talus formation, minor climatic changes thus are hardly to read clearly from

  3. Effect of rock mass structure and block size on the slope stability--Physical modeling and discrete element simulation

    Institute of Scientific and Technical Information of China (English)

    LI; Shihai; LIAN; Zhenzhong; J.; G.; Wang

    2005-01-01

    This paper studies the stability of jointed rock slopes by using our improved three-dimensional discrete element methods (DEM) and physical modeling. Results show that the DEM can simulate all failure modes of rock slopes with different joint configurations. The stress in each rock block is not homogeneous and blocks rotate in failure development. Failure modes depend on the configuration of joints. Toppling failure is observed for the slope with straight joints and sliding failure is observed for the slope with staged joints. The DEM results are also compared with those of limit equilibrium method (LEM). Without considering the joints in rock masses, the LEM predicts much higher factor of safety than physical modeling and DEM. The failure mode and factor of safety predicted by the DEM are in good agreement with laboratory tests for any jointed rock slope.

  4. A field study of the geomorphic effects of sublimating CO2 blocks on dune slopes at Coral Pink Dunes, Utah.

    Science.gov (United States)

    Bourke, Mary; Nield, Jo; Diniega, Serina; Hansen, Candy; McElwaine, Jim

    2016-04-01

    compared to the Arizona site, but a pronounced unpaired-levee formed towards the base of the lee slope. These data show that sublimating blocks of CO2 ice leave signatures of transport paths and are capable of eroding and transporting sediment. Diniega,S. et al (2013) A new dry hypothesis for the formation of Martian linear gullies. Icarus. Vol. 225, 1, p. 526-537. Bourke, M.C. et al (2016) The geomorphic effect of sublimating CO2 blocks on dune lee slopes at Grand Falls, Arizona. LPSC

  5. Effective coastal boundary conditions for tsunami wave run-up over sloping bathymetry

    NARCIS (Netherlands)

    Kristina, W.; Bokhove, O.; Groesen, van E.W.C.

    2014-01-01

    An effective boundary condition (EBC) is introduced as a novel technique for predicting tsunami wave run-up along the coast, and offshore wave reflections. Numerical modeling of tsunami propagation in the coastal zone has been a daunting task, since high accuracy is needed to capture aspects of wave

  6. Scale effects in Hortonian surface runoff on agricultural slopes in West Africa: Field data and models

    NARCIS (Netherlands)

    Giesen, van de N.; Stomph, T.J.; Ajayi, A.E.; Bagayoko, F.

    2011-01-01

    This article provides an overview of both experimental and modeling research carried out over the past 15 years by the authors addressing scaling effects in Hortonian surface runoff. Hortonian surface runoff occurs when rainfall intensity exceeds infiltration capacity of the soil. At three sites in

  7. EXPERIMENTAL STUDY ON BED SCOUR IN A 90°CHANNEL BEND

    Institute of Scientific and Technical Information of China (English)

    Masoud GHODSIAN; S. Kamal MOUSAVI

    2006-01-01

    The special feature of bend flow leads to scouring of the bed and bank. Various parameters like flow depth, flow velocity or discharge, geometry of bend and characteristics of bed material may affect the scour process. Experiments were carried out to study the effect of some important parameters on bend scour under clear water condition. Experiments were conducted in a 0.6m wide and 0.7m high flume with 90 degree bend. The lateral variations of bed slope were studied. The maximum depth of scour was correlated to densimetric Froude number, relative bend radius and relative depth of flow.

  8. Effect of Seismic Permanent Deformation on Safety and Stability of Earth-Rock Dam Slope

    Institute of Scientific and Technical Information of China (English)

    戚蓝; 陈启振; 蔡建成

    2015-01-01

    In order to study the effect of seismic permanent deformation on the safety and stability of earth-rock dam, the permanent deformation is considered as the non-design permanent load, and the stress-strain hysteresis curve is also considered when the earth is under cyclic load. The research work can make the calculation results of plastic col-lapse more accurate by including the effect of the post-earthquake degree of plastic deformation on the stability of the earth-rock dam, and the dam safety factor decreases from 2.50 to 1.90 after the magnitude-8 earthquake. Moreover, the research work will also improve the design of the earth-rock dam under abnormal operating conditions.

  9. Effectiveness of a Reduced-Risk Insecticide Based Bed Bug Management Program in Low-Income Housing

    Directory of Open Access Journals (Sweden)

    Narinderpal Singh

    2013-11-01

    Full Text Available Bed bug (Cimex lectularius L. infestations are becoming increasingly common in low-income communities. Once they are introduced, elimination is very difficult. As part of the efforts to develop effective and safe bed bug management programs, we conducted a laboratory study evaluating the efficacy of a reduced-risk insecticide—Alpine aerosol (0.5% dinotefuran. We then conducted a field evaluation of a reduced-risk insecticide based integrated pest management (IPM program in low-income family apartments with young children. In laboratory evaluations, direct spray and 5 min exposure to dry Alpine aerosol residue caused 100.0 ± 0.0 and 91.7 ± 8.3% mortality to bed bug nymphs, respectively. Direct Alpine aerosol spray killed 91.3 ± 4.3% of the eggs. The IPM program included education, steam, bagging infested linens, placing intercepting devices under furniture legs and corners of rooms, applying Alpine aerosol and Alpine dust (0.25% dinotefuran, 95% diatomaceous earth dust, and regularly scheduled monitoring and re-treatment. Nine apartments ranging from 1–1,428 (median: 29 bed bugs based on visual inspection and Climbup interceptor counts were included. Over a 6-month period, an average 172 g insecticide (Alpine aerosol + Alpine dust was used in each apartment, a 96% reduction in pesticide usage compared to chemical only treatment reported in a similar environment. The IPM program resulted in an average of 96.8 ± 2.2% reduction in the number of bed bugs. However, elimination of bed bugs was only achieved in three lightly infested apartments (<30 bed bugs at the beginning. Elimination success was closely correlated with the level of bed bug populations.

  10. Effectiveness of a Batteryless and Wireless Wearable Sensor System for Identifying Bed and Chair Exits in Healthy Older People.

    Science.gov (United States)

    Torres, Roberto Luis Shinmoto; Visvanathan, Renuka; Hoskins, Stephen; van den Hengel, Anton; Ranasinghe, Damith C

    2016-04-15

    Aging populations are increasing worldwide and strategies to minimize the impact of falls on older people need to be examined. Falls in hospitals are common and current hospital technological implementations use localized sensors on beds and chairs to alert caregivers of unsupervised patient ambulations; however, such systems have high false alarm rates. We investigate the recognition of bed and chair exits in real-time using a wireless wearable sensor worn by healthy older volunteers. Fourteen healthy older participants joined in supervised trials. They wore a batteryless, lightweight and wireless sensor over their attire and performed a set of broadly scripted activities. We developed a movement monitoring approach for the recognition of bed and chair exits based on a machine learning activity predictor. We investigated the effectiveness of our approach in generating bed and chair exit alerts in two possible clinical deployments (Room 1 and Room 2). The system obtained recall results above 93% (Room 2) and 94% (Room 1) for bed and chair exits, respectively. Precision was >78% and 67%, respectively, while F-score was >84% and 77% for bed and chair exits, respectively. This system has potential for real-time monitoring but further research in the final target population of older people is necessary.

  11. Effectiveness of a Batteryless and Wireless Wearable Sensor System for Identifying Bed and Chair Exits in Healthy Older People

    Directory of Open Access Journals (Sweden)

    Roberto Luis Shinmoto Torres

    2016-04-01

    Full Text Available Aging populations are increasing worldwide and strategies to minimize the impact of falls on older people need to be examined. Falls in hospitals are common and current hospital technological implementations use localized sensors on beds and chairs to alert caregivers of unsupervised patient ambulations; however, such systems have high false alarm rates. We investigate the recognition of bed and chair exits in real-time using a wireless wearable sensor worn by healthy older volunteers. Fourteen healthy older participants joined in supervised trials. They wore a batteryless, lightweight and wireless sensor over their attire and performed a set of broadly scripted activities. We developed a movement monitoring approach for the recognition of bed and chair exits based on a machine learning activity predictor. We investigated the effectiveness of our approach in generating bed and chair exit alerts in two possible clinical deployments (Room 1 and Room 2. The system obtained recall results above 93% (Room 2 and 94% (Room 1 for bed and chair exits, respectively. Precision was >78% and 67%, respectively, while F-score was >84% and 77% for bed and chair exits, respectively. This system has potential for real-time monitoring but further research in the final target population of older people is necessary.

  12. Gravity-induced stresses in finite slopes

    Science.gov (United States)

    Savage, W.Z.

    1994-01-01

    An exact solution for gravity-induced stresses in finite elastic slopes is presented. This solution, which is applied for gravity-induced stresses in 15, 30, 45 and 90?? finite slopes, has application in pit-slope design, compares favorably with published finite element results for this problem and satisfies the conditions that shear and normal stresses vanish on the ground surface. The solution predicts that horizontal stresses are compressive along the top of the slopes (zero in the case of the 90?? slope) and tensile away from the bottom of the slopes, effects which are caused by downward movement and near-surface horizontal extension in front of the slope in response to gravity loading caused by the additional material associated with the finite slope. ?? 1994.

  13. Grey Relational Analysis on the Effects of Rainfall Factors on Runoff and Sediment in the Sloping Farmland with Different Plants in the Central South of Shandong Province

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    [Objective] The aim was to study the main rainfall factors influencing runoff and sediment in the sloping farmland with different plants in the central south of Shandong Province.[Method] Through grey relational analysis,the effects of different rainfall factors on runoff and sediment with different plants in the central south of Shandong were studied.[Result] In the sloping farmland with different plants,the effects of rainfall factors on runoff and sediment weren't consistent.Rainfall was the dominant inf...

  14. THE EFFECT OF REINFORCEMENT ON THE GBFS AND LIME TREATED MARINE CLAY FOR FOUNDATION SOIL BEDS

    Directory of Open Access Journals (Sweden)

    D. Koteswara Rao,

    2011-03-01

    Full Text Available India being peninsular country has large area coming under coastal region and also it has been the habitat for considerable percentage of population. The marine clays are generally found in the coastal region of West Bengal, Orissa, Andhra Pradesh, Tamilnadu, Kerala, Karnataka, Maharashtra and some parts of Gujarat. Marine or soft clays exists in these region are weak and deformative in nature. The present study deals with the strength characteristics of the marine clay collected from Kakinada Sea Port Ltd, Kakinada, A.P, India. The effect of lime on the strength characteristics of marine clay are studied in this investigation along with the reinforcement effect using geotextile as reinforcement and separator for the foundation soil bed.

  15. Negative effects of blue mussel ( Mytilus edulis) presence in eelgrass ( Zostera marina) beds in Flensborg fjord, Denmark

    Science.gov (United States)

    Vinther, Hanne Fogh; Laursen, Jens Sund; Holmer, Marianne

    2008-03-01

    The effect of blue mussel ( Mytilus edulis) presence in eelgrass ( Zostera marina) beds was studied from June 2004 to July 2005 in Flensborg fjord, Denmark. The field experiments were conducted at two stations, one with only Z. marina (Eelgrass station) present and one where M. edulis were present in the Z. marina beds (Mixed station). Zostera marina parameters were measured (growth of leaves, shoot density, leaf length, and nutrient content) in combination with epiphyte cover and sediment parameters (sulphate reduction rates, sediment nutrient fluxes, organic content, C, N and P content) to examine possible positive and negative effects of the mussels on eelgrass performance. The fluxes of ammonium from the sediments were stimulated at all sampling dates at the Mixed station, and possibly stimulated epiphyte growth at this station. Further 15N signals in epiphytes from the Mixed station suggested that excretion products from the mussels were important nitrogen sources at this station. Sulphate reduction rates were enhanced at the Mixed station and also sediment sulphide concentrations increased under mussel influence, which may have resulted in sulphide toxicity and decreased growth of Z. marina at this station. The study indicates that for Z. marina beds in Flensborg Fjord the effects of M. edulis in seagrass beds are primarily negative, and raises the question whether this leads to negative effects on the stability and expansion of Z. marina beds.

  16. Effects of aligning pulse duration on the degree and the slope of nitrogen field-free alignment

    Institute of Scientific and Technical Information of China (English)

    Wang Fei; Jiang Hong-Bing; Gong Qi-Huang

    2012-01-01

    Through theoretical analysis,we show how aligning pulse durations affect the degree and the time-rate slope of nitrogen field-free alignment at a fixed pulse intensity.It is found that both the degree and the slope first increase,then saturate,and finally decrease with the increasing pump duration.The optimal durations for the maximum degree and the maximum slope of the alignment are found to be different.Additionally,they are found to mainly depend on the molecular rotational period,and are affected by the temperature and the aligning pump intensities.The mechanism of molecular alignment is also discussed.

  17. Mesoscale Characterization of Coupled Hydromechanical Behavior of a Fractured Porous Slope in Response to Free Water-Surface Movement

    Energy Technology Data Exchange (ETDEWEB)

    Rutqvist, Jonny; Guglielmi, Y.; Cappa, F.; Rutqvist, J.; Tsang, C.-F.; Thoraval, A.

    2008-05-15

    To better understand the role of groundwater-level changes on rock-slope deformation and damage, a carbonate rock slope (30 m x 30 m x 15 m) was extensively instrumented for mesoscale hydraulic and mechanical measurements during water-level changes. The slope is naturally drained by a spring that can be artificially closed or opened by a water gate. In this study, a 2-hour slope-dewatering experiment was analyzed. Changes in fluid pressure and deformation were simultaneously monitored, both at discontinuities and in the intact rock, using short-base extensometers and pressure gauges as well as tiltmeters fixed at the slope surface. Field data were analyzed with different coupled hydromechanical (HM) codes (ROCMAS, FLAC{sup 3D}, and UDEC). Field data indicate that in the faults, a 40 kPa pressure fall occurs in 2 minutes and induces a 0.5 to 31 x 10{sup -6} m normal closure. Pressure fall is slower in the bedding-planes, lasting 120 minutes with no normal deformation. No pressure change or deformation is observed in the intact rock. The slope surface displays a complex tilt towards the interior of the slope, with magnitudes ranging from 0.6 to 15 x 10{sup -6} rad. Close agreement with model for both slope surface and internal measurements is obtained when a high variability in slope-element properties is introduced into the models, with normal stiffnesses of k{sub n{_}faults} = 10{sup -3} x k{sub n{_}bedding-planes} and permeabilities of k{sub h{_}faults} = 10{sup 3} x k{sub h{_}bedding-planes}. A nonlinear correlation between hydraulic and mechanical discontinuity properties is proposed and related to discontinuity damage. A parametric study shows that 90% of slope deformation depends on HM effects in a few highly permeable and highly deformable discontinuities located in the basal, saturated part of the slope while the remaining 10% are related to elasto-plastic deformations in the low-permeability discontinuities induced by complex stress/strain transfers from

  18. NONUNIFORM OPEN CHANNEL FLOW WITH UPWARD SEEPAGE THROUGH LOOSE BEDS

    Institute of Scientific and Technical Information of China (English)

    Subhasish DEY

    2003-01-01

    The Reynolds stress and bed shear stress are important parameters in fluvial hydraulics. Steadynonuniform flow in open channels with streamwise sloping beds having upward seepage through loose beds is theoretically analyzed to estimate the Reynolds stress and bed shear stress. Equations of the Reynolds stress and bed shear stress are developed, assuming a modified logarithmic velocity distribution law due to upward seepage, and using the Reynolds and continuity equations of twodimensional flow in open channels.

  19. Bed-levelling experiments with suspended load

    NARCIS (Netherlands)

    Talmon, A.M.; De Graaff, J.

    1991-01-01

    Bed-levelling experiments are conducted in a straight laboratory channel. The experiments involve a significant fraction of suspended sediment transport. The purpose of the experiments is to provide data for modelling of the direction of sediment transport on a transverse sloping alluvial river bed,

  20. Edge effects are important in supporting beetle biodiversity in a gravel-bed river floodplain.

    Directory of Open Access Journals (Sweden)

    Simone D Langhans

    Full Text Available Understanding complex, dynamic, and diverse ecosystems is essential for developing sound management and conservation strategies. Gravel-bed river floodplains are composed of an interlinked mosaic of aquatic and terrestrial habitats hosting a diverse, specialized, and endangered fauna. Therefore, they serve as excellent models to investigate the biodiversity of multiple ecotones and related edge effects. In this study, we investigated the abundance, composition, richness, and conservation status of beetle assemblages at varying sediment depth (0, 0.1, 0.6 and 1.1 m, distance from the channel (1, 5, 20, and 60-100 m, and 5 m within the riparian forest, and time of the year (February-November across a 200 m-wide gravel bar at the near-natural Tagliamento River (Italy, to detect edge effects in four floodplain ecotones: aquatic-terrestrial, forest-active floodplain, sediment-air, and sediment-groundwater. We used conventional pitfall traps and novel tube traps to sample beetles comparably on the sediment surface and within the unsaturated sediments. We found a total of 308 beetle species (including 87 of conservation concern that showed multiple, significant positive edge effects across the floodplain ecotones, mainly driven by spatial heterogeneity: Total and red list beetle abundance and richness peaked on the sediment surface, at channel margins, and at the edge of the riparian forest. All ecotones possessed edge/habitat specialists. Most red list species occurred on the sediment surface, including five species previously considered extinct--yet two of these species occurred in higher densities in the unsaturated sediments. Conservation and management efforts along gravel-bed rivers must therefore promote a dynamic flow and sediment regime to create and maintain habitat heterogeneity and ecotone diversity, which support a unique and high biodiversity.

  1. Edge effects are important in supporting beetle biodiversity in a gravel-bed river floodplain.

    Science.gov (United States)

    Langhans, Simone D; Tockner, Klement

    2014-01-01

    Understanding complex, dynamic, and diverse ecosystems is essential for developing sound management and conservation strategies. Gravel-bed river floodplains are composed of an interlinked mosaic of aquatic and terrestrial habitats hosting a diverse, specialized, and endangered fauna. Therefore, they serve as excellent models to investigate the biodiversity of multiple ecotones and related edge effects. In this study, we investigated the abundance, composition, richness, and conservation status of beetle assemblages at varying sediment depth (0, 0.1, 0.6 and 1.1 m), distance from the channel (1, 5, 20, and 60-100 m, and 5 m within the riparian forest), and time of the year (February-November) across a 200 m-wide gravel bar at the near-natural Tagliamento River (Italy), to detect edge effects in four floodplain ecotones: aquatic-terrestrial, forest-active floodplain, sediment-air, and sediment-groundwater. We used conventional pitfall traps and novel tube traps to sample beetles comparably on the sediment surface and within the unsaturated sediments. We found a total of 308 beetle species (including 87 of conservation concern) that showed multiple, significant positive edge effects across the floodplain ecotones, mainly driven by spatial heterogeneity: Total and red list beetle abundance and richness peaked on the sediment surface, at channel margins, and at the edge of the riparian forest. All ecotones possessed edge/habitat specialists. Most red list species occurred on the sediment surface, including five species previously considered extinct--yet two of these species occurred in higher densities in the unsaturated sediments. Conservation and management efforts along gravel-bed rivers must therefore promote a dynamic flow and sediment regime to create and maintain habitat heterogeneity and ecotone diversity, which support a unique and high biodiversity.

  2. COUPLING EFFECT BETWEEN RELIABILITY OF BEDDING LAYER AND STABILITY OF DOWNSTREAM CONCRETE SLAB OF OVERFLOW EARTH-ROCK COFFERDAM

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The protection of downstream concrete slab is a key issue for the stability of overflow earth-rock cofferdam. The coupling effect between bedding layer and concrete slab was taken into account when the stability of downstream concrete slab was researched. The characteristics of overflow and seepage over the downstream concrete slab were investigated when floodwater passes over the cofferdam. Firstly a limit equation of seepage failure for the bedding layer was derived with the consideration of geometric and mechanical factors, and a reliability model was established and numerically simulated. Then based on the reliability calculation for the bedding layer, the coupling effect between bedding layer and downstream concrete slab was analyzed. Under the most unfavorable pressure condition for the concrete slab, its instability criterion was put forward, which offers a structural design tool of downstream concrete slab for overflow earth-rock cofferdam. Compared with model tests, it shows that the model of reliability calculation of bedding layer and the stability analysis of downstream concrete slab are effective.

  3. Haulage Vehicle Traffic and Runoff Effect on Gully Growth on Roadside Slopes of Unpaved Sand-Quarry Road, Uyo.

    Directory of Open Access Journals (Sweden)

    Obot Ekpo Essien

    2013-10-01

    Full Text Available Rainfall runoff and sand haulage truck traffic count were quantified and regressed on gully soil loss and gully morphometric volume growth on unpaved haulage roadside erosion. The gully erosion on unpaved roadside was accelerated by the agency of runoff in splash wash from the road, and high axle sand haulage trucks traffic. The effect of the Runoff discharge and traffic count, as independent variables and cumulativequantities, on the cumulative soil loss from jagged side slope gullies, and the gully volume growth were very significant at P < 0.01 generally. Predictive coefficient of determination, significant at P < 0.01, were very perfect at R2= 88.8 to 98.9%. Different regimes of association were obtained such as: high runoff and high traffic count; high flow rate and low traffic count, and low runoff and high traffic count for effect and on gully loss and gully volume growth, and they gave accurate and significant relationship. Regulation of sand-mining over a catchment is recommended as it has otherwise destroyed landform and initiated unrestrained gullying.

  4. Zebra mussel beds: an effective feeding ground for Ponto-Caspian gobies or suitable shelter for their prey?

    Directory of Open Access Journals (Sweden)

    Jarosław Kobak

    2016-11-01

    Full Text Available Aggregations of the Ponto-Caspian invasive zebra mussel (Dreissena polymorpha constitute a suitable habitat for macroinvertebrates, considerably increasing their abundance and providing effective antipredator protection. Thus, the overall effect of a mussel bed on particular predator species may vary from positive to negative, depending on both prey density increase and predator ability to prey in a structurally complex habitat. Alien Ponto-Caspian goby fish are likely to be facilitated when introduced into new areas by zebra mussels, provided that they are capable of utilizing mussel beds as habitat and feeding grounds. We ran laboratory experiments to find which prey (chironomid larvae densities (from ca. 500 to 2,000 individuals m−2 in a mussel bed make it a more beneficial feeding ground for the racer goby Babka gymnotrachelus (RG and western tubenose goby Proterorhinus semilunaris (WTG compared to sandy and stone substrata (containing the basic prey density of 500 ind. m−2. Moreover, we checked how food availability affects habitat selection by fish. Mussel beds became more suitable for fish than alternative mineral substrata when food abundance was at least two times higher (1,000 vs. 500 ind. m−2, regardless of fish size and species. WTG was associated with mussel beds regardless of its size and prey density, whereas RG switched to this habitat when it became a better feeding ground than alternative substrata. Larger RG exhibited a stronger affinity for mussels than small individuals. WTG fed more efficiently from a mussel bed at high food abundances than RG. A literature review has shown that increasing chironomid density, which in our study was sufficient to make a mussel habitat an attractive feeding ground for the gobies, is commonly observed in mussel beds in the field. Therefore, we conclude that zebra mussels may positively affect the alien goby species and are likely to facilitate their establishment in novel areas

  5. Effects of head-down bed rest on complex heart rate variability: Response to LBNP testing

    Science.gov (United States)

    Goldberger, Ary L.; Mietus, Joseph E.; Rigney, David R.; Wood, Margie L.; Fortney, Suzanne M.

    1994-01-01

    Head-down bed rest is used to model physiological changes during spaceflight. We postulated that bed rest would decrease the degree of complex physiological heart rate variability. We analyzed continuous heart rate data from digitized Holter recordings in eight healthy female volunteers (age 28-34 yr) who underwent a 13-day 6 deg head-down bed rest study with serial lower body negative pressure (LBNP) trials. Heart rate variability was measured on a 4-min data sets using conventional time and frequency domain measures as well as with a new measure of signal 'complexity' (approximate entropy). Data were obtained pre-bed rest (control), during bed rest (day 4 and day 9 or 11), and 2 days post-bed rest (recovery). Tolerance to LBNP was significantly reduced on both bed rest days vs. pre-bed rest. Heart rate variability was assessed at peak LBNP. Heart rate approximate entropy was significantly decreased at day 4 and day 9 or 11, returning toward normal during recovery. Heart rate standard deviation and the ratio of high- to low-power frequency did not change significantly. We conclude that short-term bed rest is associated with a decrease in the complex variability of heart rate during LBNP testing in healthy young adult women. Measurement of heart rate complexity, using a method derived from nonlinear dynamics ('chaos theory'), may provide a sensitive marker of this loss of physiological variability, complementing conventional time and frequency domain statistical measures.

  6. Comparison of the Effects of Fluidized-Bed and Fixed-Bed Reactors in Microwave-Assisted Catalytic Decomposition of TCE by Hydrogen

    Directory of Open Access Journals (Sweden)

    Lili Ren

    2012-01-01

    Full Text Available Trichloroethylene (TCE decomposition by hydrogen with microwave heating under different reaction systems was investigated. The activities of a series of catalysts for microwave-assisted TCE hydrodechlorination were tested through the fixed-bed and the fluidized-bed reactor systems. This study found that the different reaction system is suitable for different catalyst type. And there is an interactive relationship between the catalyst type and the reaction bed type.

  7. Effect of Climatic Conditions on Differences in Thermo-Technical Properties of Organic Bedding in Laboratory Testing

    Directory of Open Access Journals (Sweden)

    Lendelová Jana

    2017-03-01

    Full Text Available The aim of this experiment was to analyse the influence of climatic factors on the thermal performance of separated liquid manure. The samples of organic bedding were collected from the lying area of dairy housing and preparatory store. The measurement of properties of recycled manure solids (RMS was carried out in laboratory conditions. Samples were examined with determining the temperature effect on the thermal conductivity λ of ’dry‘ separated liquid manure (with a dry matter content of 60% and ’wet‘ liquid manure (with a dry matter content of 26%, in air temperatures ranging from 0 °C to 40 °C. Subsequently, the thermal resistance of three selected types of cows lying structures was calculated for winter and summer boundary values. Based on the results of thermal conductivity and thermal resistance, it was observed that dry separated liquid manure as an alternative bedding has, in low temperature (up to 5 °C, the most suitable thermal performance if it is maintained in a dry condition (with a dry matter content of 60%. With increasing temperature (above 20 °C and increasing humidity of bedding (below 26%, thermo-technical properties get worse; however, when comparing the thermal resistance of the cow bed structure with sandwich mattresses with a 50 mm layer of organic bedding and the deep cubicle filled with 200 mm of organic bedding, the thermal resistance of floor structure decreases by 7.6% or 18.4%, respectively. With a proper handling of the recycled organic bedding, it is possible to use its economic advantages.

  8. Effectiveness of powered hospital bed movers for reducing physiological strain and back muscle activation.

    Science.gov (United States)

    Daniell, Nathan; Merrett, Simon; Paul, Gunther

    2014-07-01

    Battery powered bed movers are becoming increasingly common within the hospital setting. The use of powered bed movers is believed to result in reduced physical efforts required by health care workers, which may be associated with a decreased risk of occupation related injuries. However, little work has been conducted assessing how powered bed movers impact on levels of physiological strain and muscle activation for the user. The muscular efforts associated with moving hospital beds using three different methods; powered StaminaLift Bed Mover (PBM1), powered Gzunda Bed Mover (PBM2) and manual pushing were measured on six male subjects. Fourteen muscles were assessed moving a weighted hospital bed along a standardized route in an Australian hospital environment. Trunk inclination and upper spine acceleration were also quantified. Powered bed movers exhibited significantly lower muscle activation levels than manual pushing for the majority of muscles. When using the PBM1, users adopted a more upright posture which was maintained while performing different tasks (e.g. turning a corner, entering a lift), while trunk inclination varied considerably for manual pushing and the PBM2. The reduction in lower back muscular activation levels may result in lower incidence of lower back injury.

  9. Effects of Long Duration Spaceflight on Venous and Arterial Compliance: Bed Rest

    Science.gov (United States)

    Ribeiro, L. Christine; Platts, Steven H.; Laurie, Steven S.; Lee, Stuart M. C.; Martin, David S.; Ploutz-Snyder, Robert J.; Stenger, Michael B.

    2017-01-01

    The primary objective was to determine whether a high sodium diet during bed rest induced alterations in vascular compliance and was related to the incidence of VIIP. Ocular structural and functional measures and vascular ultrasound of the head and neck were acquired in bed rest subjects completing 10-14 days in 6deg head-down tilt.

  10. An aerated and fluidized bed membrane bioreactor for effective wastewater treatment with low membrane fouling

    KAUST Repository

    Ye, Yaoli

    2016-09-24

    Anaerobic fluidized bed membrane bioreactors (AFMBRs) use granular activated carbon (GAC) particles suspended by recirculation to effectively treat low strength wastewaters (∼100–200 mg L−1, chemical oxygen demand, COD), but the effluent can contain dissolved methane. An aerobic fluidized bed membrane bioreactor (AOFMBR) was developed to avoid methane production and the need for wastewater recirculation by using rising air bubbles to suspend GAC particles. The performance of the AOFMBR was compared to an AFMBR and a conventional aerobic membrane bioreactor (AeMBR) for domestic wastewater treatment over 130 d at ambient temperatures (fixed hydraulic retention time of 1.3 h). The effluent of the AOFMBR had a COD of 20 ± 8 mg L−1, and a turbidity of <0.2 NTU, for low-COD influent (153 ± 19 and 214 ± 27 mg L−1), similar to the AeMBR and AFMBR. For the high-COD influent (299 ± 24 mg L−1), higher effluent CODs were obtained for the AeMBR (38 ± 9 mg L−1) and AFMBR (51 ± 11 mg L−1) than the AOFMBR (26 ± 6 mg L−1). Transmembrane pressure of the AOFMBR increased at 0.04 kPa d−1, which was 20% less than the AeMBR and 57% less than the AFMBR, at the low influent COD. Scanning electron microscopy (SEM) analysis indicated a more uniform biofilm on the membrane in AOFMBR than that from the AeMBR biofilm, and no evidence of membrane damage. High similarity was found between communities in the suspended sludge in the AOFMBR and AeMBR (square-root transformed Bray–Curtis similarity, SRBCS, 0.69). Communities on the GAC and suspended sludge were dissimilar in the AOFMBR (SRBCS, 0.52), but clustered in the AFMBR (SRBCS, 0.63).

  11. The effect of coal bed dewatering and partial oxidation on biogenic methane potential

    Science.gov (United States)

    Jones, Elizabeth J.P.; Harris, Steve H.; Barnhart, Elliott P.; Orem, William H.; Clark, Arthur C.; Corum, Margo D.; Kirshtein, Julie D.; Varonka, Matthew S.; Voytek, Mary A.

    2013-01-01

    Coal formation dewatering at a site in the Powder River Basin was associated with enhanced potential for secondary biogenic methane determined by using a bioassay. We hypothesized that dewatering can stimulate microbial activity and increase the bioavailability of coal. We analyzed one dewatered and two water-saturated coals to examine possible ways in which dewatering influences coal bed natural gas biogenesis by looking at differences with respect to the native coal microbial community, coal-methane organic intermediates, and residual coal oxidation potential. Microbial biomass did not increase in response to dewatering. Small Subunit rRNA sequences retrieved from all coals sampled represented members from genera known to be aerobic, anaerobic and facultatively anaerobic. A Bray Curtis similarity analysis indicated that the microbial communities in water-saturated coals were more similar to each other than to the dewatered coal, suggesting an effect of dewatering. There was a higher incidence of long chain and volatile fatty acid intermediates in incubations of the dewatered coal compared to the water-saturated coals, and this could either be due to differences in microbial enzymatic activities or to chemical oxidation of the coal associated with O2 exposure. Dilute H2O2 treatment of two fractions of structural coal (kerogen and bitumen + kerogen) was used as a proxy for chemical oxidation by O2. The dewatered coal had a low residual oxidation potential compared to the water-saturated coals. Oxidation with 5% H2O2 did increase the bioavailability of structural coal, and the increase in residual oxidation potential in the water saturated coals was approximately equivalent to the higher methanogenic potential measured in the dewatered coal. Evidence from this study supports the idea that coal bed dewatering could stimulate biogenic methanogenesis through partial oxidation of the structural organics in coal once anaerobic conditions are restored.

  12. Numerical simulation of dune-flat bed transition and stage-discharge relationship with hysteresis effect

    Science.gov (United States)

    Shimizu, Y.; Giri, S.; Yamaguchi, S.; Nelson, Jack L.

    2009-01-01

    This work presents recent advances on morphodynamic modeling of bed forms under unsteady discharge. This paper includes further development of a morphodynamic model proposed earlier by Giri and Shimizu (2006a). This model reproduces the temporal development of river dunes and accurately replicates the physical properties associated with bed form evolution. Model results appear to provide accurate predictions of bed form geometry and form drag over bed forms for arbitrary steady flows. However, accurate predictions of temporal changes of form drag are key to the prediction of stage-discharge relation during flood events. Herein, the model capability is extended to replicate the dune-flat bed transition, and in turn, the variation of form drag produced by the temporal growth or decay of bed forms under unsteady flow conditions. Some numerical experiments are performed to analyze hysteresis of the stage-discharge relationship caused by the transition between dune and flat bed regimes during rising and falling stages of varying flows. The numerical model successfully simulates dune-flat bed transition and the associated hysteresis of the stage-discharge relationship; this is in good agreement with physical observations but has been treated in the past only using empirical methods. A hypothetical relationship for a sediment parameter (the mean step length) is proposed to a first level of approximation that enables reproduction of the dune-flat bed transition. The proposed numerical model demonstrates its ability to address an important practical problem associated with bed form evolution and flow resistance in varying flows. Copyright 2009 by the American Geophysical Union.

  13. Feature of resistivity response of slope from steady to unsteady

    Institute of Scientific and Technical Information of China (English)

    谢忠球; 张玉池; 温佩琳; 段靓靓

    2008-01-01

    Using resistivity as index and referring to the law about effect of slope to resistivity,the apparent resistivities of geophysical model concerned with unsteady rock type slope failure were calculated systematically by using the boundary integral equation method.After studying the feature of resistivity response of slope failure,the variety of resistivity during evolution of slope from steady to unsteady was found and the characteristics of resistivity response about slope failure was concluded.These make electrical exploring method for detecting the slip plane or structural plane of slope failure,evaluating the stability of the slope,and forecasting slope failure become true.

  14. Biomass-Ash-Induced Agglomeration in a Fluidized Bed. Part 1: Experimental Study on the Effects of a Gas Atmosphere

    DEFF Research Database (Denmark)

    Ma, Teng; Fan, Chuigang; Hao, Lifang

    2016-01-01

    Fluidized beds have been widely applied to gasification and combustion of biomass. During gasification, a high temperature is preferable to increase the carbon conversion and to reduce the undesirable tar. However, the high temperature may lead to a severe agglomeration problem in a fluidized bed....... Understanding of the agglomeration in various atmospheres is crucial to optimize the design and operation conditions. This study focuses on the effects of gases on agglomeration tendency with different types of biomass, including corn straw, rice straw, and wheat straw. The biomass ash samples are mixed...

  15. Effects of gravitational stress, hypokinesia and hypodynamia on the structure of the vascular bed of the spleen

    Science.gov (United States)

    Nesterenko, N. T.

    1980-01-01

    The effects of two extreme factors, hypokinesia and hypodynamia, on spleen vascular beds were studied on 180 male and female albino rats. Vessels were studied by roentgenography, microroentgenography, clearing of sections and histology. Gravity stress yielded construction of all links of arterial bed and of order 5-7 veins. Large intraorganic vein diameters changed significantly but erratically. Hypokinesia in early phases produced pronounced spleen size reduction. Veins and arteries constricted along entire length. Later hypokinetic stages showed arteries still constricted; veins began to dilate from week 4 of hypokinesia. Sinuosity, uneven contours and varicose dilations of walls in large arteries and veins occurred. Abrupt changes in parenchyma, e.g., atrophy of folliculi, narrowing of lumen of central arteries from thickening of muscular wall. After exposure to hypokinesia followed by gravitational stress, pronounced lesions such as deformation of vascular wall, including rupture, in all vessels of the spleen vascular bed.

  16. High short-term effectiveness of modulated dry bed training in adolescents and young adults with treatment-resistant enuresis

    NARCIS (Netherlands)

    Hofmeester, I.; Cobussen-Boekhorst, J.G.L.; Kortmann, B.B.M.; Mulder, Z.; Steffens, M.G.; Feitz, W.F.J.; Van Capelle, J.W.; Blanker, M.H.

    2015-01-01

    INTRODUCTION & OBJECTIVES: Two percent of adolescents and young adults suffer from therapy-resistant enuresis, with considerable negative impact on self-esteem and relationships. We evaluated the effect of a Modulated Dry Bed Training (MDBT) in a previously therapyresistant group of adolescents with

  17. High short-term effectiveness of modulated dry bed training in adolescents and young adults with treatment-resistant enuresis

    NARCIS (Netherlands)

    Hofmeester, I.; Cobussen-Boekhorst, J.G.L.; Kortmann, B.B.M.; Mulder, Z.; Steffens, M.G.; Feitz, W.F.J.; Van Capelle, J.W.; Blanker, M.H.

    2015-01-01

    Hypothesis/aims of study Two percent of adolescents and adults suffers from enuresis. In this age group, social problems can arise. We evaluated the effect of a Modulated Dry Bed Training (MDBT) in a previously therapy-resistant group of adolescents and adults with enuresis, provided by a specialize

  18. Effect of 2 Bedding Materials on Ammonia Levels in Individually Ventilated Cages.

    Science.gov (United States)

    Koontz, Jason M; Kumsher, David M; Kelly, Richard; Stallings, Jonathan D

    2016-01-01

    This study sought to identify an optimal rodent bedding and cage-change interval to establish standard procedures for the IVC in our rodent vivarium. Disposable cages were prefilled with either corncob or α-cellulose bedding and were used to house 2 adult Sprague-Dawley rats (experimental condition) or contained no animals (control). Rats were observed and intracage ammonia levels measured daily for 21 d. Intracage ammonia accumulation became significant by day 8 in experimental cages containing α-cellulose bedding, whereas experimental cages containing corncob bedding did not reach detectable levels of ammonia until day 14. In all 3 experimental cages containing α-cellulose, ammonia exceeded 100 ppm (our maximum acceptable limit) by day 11. Two experimental corncob cages required changing at days 16 and 17, whereas the remaining cage containing corncob bedding lasted the entire 21 d without reaching the 100-ppm ammonia threshold. These data suggests that corncob bedding provides nearly twice the service life of α-cellulose bedding in the IVC system.

  19. Effect of 2 Bedding Materials on Ammonia Levels in Individually Ventilated Cages

    Science.gov (United States)

    Koontz, Jason M; Kumsher, David M; III, Richard Kelly; Stallings, Jonathan D

    2016-01-01

    This study sought to identify an optimal rodent bedding and cage-change interval to establish standard procedures for the IVC in our rodent vivarium. Disposable cages were prefilled with either corncob or α-cellulose bedding and were used to house 2 adult Sprague–Dawley rats (experimental condition) or contained no animals (control). Rats were observed and intracage ammonia levels measured daily for 21 d. Intracage ammonia accumulation became significant by day 8 in experimental cages containing α-cellulose bedding, whereas experimental cages containing corncob bedding did not reach detectable levels of ammonia until day 14. In all 3 experimental cages containing α-cellulose, ammonia exceeded 100 ppm (our maximum acceptable limit) by day 11. Two experimental corncob cages required changing at days 16 and 17, whereas the remaining cage containing corncob bedding lasted the entire 21 d without reaching the 100-ppm ammonia threshold. These data suggests that corncob bedding provides nearly twice the service life of α-cellulose bedding in the IVC system. PMID:26817976

  20. THE 05.06.2012 SLOPE FLOOD RUNOFF IN THE LOWER BASIN OF ILIŞUA RIVER – CAUSES, EFFECTS AND FUTURE MEASURES

    Directory of Open Access Journals (Sweden)

    Gh. Şerban

    2013-03-01

    Full Text Available In the context of the Code Yellow for rainfalls and storms, issued by National Administration of Meteorology (NAM, a downpoor occurred on the 5th of June 2012 in the afternoon, between 16.00 and 16.30 hours, with maximum intensity in the area of the Dobric – Dobricel – Spermezeu – Păltineasa – Dumbrăviţa – Căianu Mare – Căianu Mic localities. The extreme meteorological event has caused a severe slope runoff. Fortunately, the effects did not include any victims, although they were very severe, judging by the blocking of tens of kilometres of road, the flooding of almost 200 households and several hundreds of hectares of agricultural land. The risk map showing the occurrence distribution of slope flood runoff and associate meteorological events reveals the need of implementing strict measures consisting in: partial afforestation of the two thirds of the cleared slopes, management and diversion of floods that discharge their liquid and alluvial material over the human settlements located in the closest proximity of the slopes, resizing of the access infrastructure (bridges, footbridges and flood defence infrastructure (dams, runoff drainage system, scenario-based training of population to react promptly to the development of the extreme hydrometeorological events. On the contrary, the questionnaires applied in the study area reveal a lower preparedness level of the population for an efficient, optimum reaction, in order to significantly reduce the effects of these phenomena.

  1. Effects of Pulse Ultrasound on Adsorption of Geniposide on Resin 1300 in a Fixed Bed

    Institute of Scientific and Technical Information of China (English)

    陆向红; 徐之超; 计建炳

    2011-01-01

    The effects of pulse ultrasound with different pulse parameters on the breakthrough curves of Geniposide on Resin 1300 were studied. The mass transfer model describing the adsorption process was constructed. Adsorption capability and the overall mass-transfer coefficient were obtained by fitting the constructed mass-transfer model and the experimental data. The effects of pulse ultrasound on adsorption of Geniposide on Resin1300 in a fixed bed were studied and compared. Amount of Geniposide adsorbed on Resin 1300 in the presence of ultrasound is lower than that in the absence of ultrasound, but the mass-transfer rate with ultrasonic irradiation is higher than that without ultrasound. Furthermore, mass transfer rate is enhanced by pulse modulation. In the conditions studied, the adsorption equilibrium constant decreases with increasing ultrasonic power, while the overall mass-transfer co-efficient increases. With increasing pulse duty ratio, adsorption equilibrium constant decreases initially, reaches a minimum when pulse duty ratio is 0.5, and then increases. On the contrary, the overall mass-transfer coefficient in-creases initially and reaches a maximum when pulse ratio is 0.5, and then decreases. Effects of pulse period on ad-sorption equilibrium and mass transfer rate reached the peak at pulse period of 28.6 ms.

  2. Effects of cohesion on the flow patterns of granular materials in spouted beds

    Science.gov (United States)

    Zhu, Runru; Li, Shuiqing; Yao, Qiang

    2013-02-01

    Two-dimensional spouted bed, capable to provide both dilute granular gas and dense granular solid flow patterns in one system, was selected as a prototypical system for studying granular materials. Effects of liquid cohesion on such kind of complex granular patterns were studied using particle image velocimetry. It is seen that the addition of liquid oils by a small fraction of 10-3-10-2 causes a remarkable narrowing (about 15%) of the spout area. In the dense annulus, as the liquid fraction increases, the downward particle velocity gradually decreases and approaches a minimum where, at a microscopic grain scale, the liquid bridge reaches spherical regimes with a maximum capillarity. Viscous lubrication effect is observed at a much higher fraction but is really weak with respect to the capillary effect. In the dilute spout, in contrast to the dry grains, the wet grains have a lightly smaller acceleration in the initial 1/3 of the spout, but have a dramatically higher acceleration in the rest of the spout. We attribute the former to the additional work needed to overcome interparticle cohesion during particle entrainment at the spout-annulus interface. Then, using mass and momentum balances, the latter is explained by the relative higher drag force resulting from both higher gas velocities and higher voidages due to spout narrowing in the wet system. The experimental findings will provide useful data for the validation of discrete element simulation of cohesive granular-fluid flows.

  3. Effects of Artificial Gravity and Bed Rest on Spatial Orientation and Balance Control

    Science.gov (United States)

    Paloski, William H.; Moore, S. T.; Feiveson, A. H.; Taylor, L. C.

    2007-01-01

    While the vestibular system should be well-adapted to bed rest (a condition it experiences approximately 8/24 hrs each day), questions remain regarding the degree to which repeated exposures to the unusual gravito-inertial force environment of a short-radius centrifuge might affect central processing of vestibular information used in spatial orientation and balance control. Should these functions be impaired by intermittent AG, its feasibility as a counter-measure would be diminished. We, therefore, examined the effects of AG on spatial orientation and balance control in 15 male volunteers before and after 21 days of 6 HDT bed rest (BR). Eight of the subjects were treated with daily 1hr AG exposures (2.5g at the feet; 1.0g at the heart) aboard a short radius (3m) centrifuge, while the other seven served as controls (C). Spatial orientation was assessed by measures of ocular counter-rolling (OCR; rotation of the eye about the line of sight, an otolith-mediated reflex) and subjective visual vertical (SVV; perception of the spatial upright). Both OCR and SVV measurements were made with the subject upright, lying on their left sides, and lying on their right sides. OCR was measured from binocular eye orientation recordings made while the subjects fixated for 10s on a point target directly in front of the face at a distance of 1 m. SVV was assessed by asking subjects (in the dark) to adjust to upright (using a handheld controller) the orientation of a luminous bar randomly perturbed (15) to either side of the vertical meridian. Balance control performance was assessed using a computerized dynamic posturography (CDP) protocol similar to that currently required for all returning crew members. During each session, the subjects completed a combination of trials of sensory organization test (SOT) 2 (eyes closed, fixed platform) and SOT 5 (eyes closed, sway-referenced platform) with and without static and dynamic pitch plane head movements (plus or minus 20 deg., dynamic

  4. Effects of 30-, 60-, and 90-Day Bed Rest on Postural Control in Men and Women

    Science.gov (United States)

    Esteves, Julie; Taylor, Laura C.; Vanya, Robert D.; Dean, S. Lance; Wood, Scott J.

    2011-01-01

    INTRODUCTION Head-down-tilt bed rest (HDT) has been used as a safe gr ound-based analog to mimic and develop countermeasures for the physiological effects of spaceflight, including decrements in postural stability. The purpose of this investigation was to characterize the effects of 30-, 60-, and 90-day bed rest on postural control in men and women. METHODS Twenty-nine subjects (18M,11F) underwent 13 days of ambula tory acclimatization and were placed in 6? HDT for 30 (n=12), 60 (n=8), or 90 (n=9) days, followed by 14 days of ambulatory recovery. Computerized dynamic posturography (CDP) was used to assess changes in sensory and motor components of postural control, and recovery after HDT. Sensory Organization Tests (SOTs) objectively evaluate one?s ability to effectively use or suppress visual, vestibular, and proprioceptive information for postural control. Stability during the SOTs was assessed using peak-to-peak sway and convergence toward stability limits to derive an equilibrium score. Motor Control Tests (MCTs) evaluate one?s ability to recover from unexpected support surface perturbations, with performance determined by center-of-pressure path length. Whole-body kinematic data were collected to determine body-sway strategy used to maintain stability during each condition. Baselines were determined pre-HDT. Recovery was tracked post-HDT on days 0, 1, 2, and 4. RESULTS Immediately after HDT, subjects showed decreased performance on most SOTs, primarily on sway-referenced support conditions, typically returning to baseline levels within 4 days. MCT performance was not significantly affected. There were no significant gender or duration differences in performance. Kinematic data revealed a tendency to use ankle strategy to maintain an upright stance during most SOT conditions. Interestingly, six subjects (2M,4F) experienced orthostatic intolerance and were unable to complete day 0 testing. CONCLUSION HDT mimics some un loading mechanisms of spaceflight and

  5. Practical aspects and uncertainty analysis of biological effective dose (BED) regarding its three-dimensional calculation in multiphase radiotherapy treatment plans

    Energy Technology Data Exchange (ETDEWEB)

    Kauweloa, Kevin I., E-mail: Kauweloa@livemail.uthscsa.edu; Gutierrez, Alonso N.; Bergamo, Angelo; Stathakis, Sotirios; Papanikolaou, Nikos; Mavroidis, Panayiotis [Department of Radiology, University of Texas Health Science Center at San Antonio, San Antonio, Texas 78229 and Cancer Therapy and Research Center, San Antonio, Texas 78229 (United States)

    2014-07-15

    Purpose: There is a growing interest in the radiation oncology community to use the biological effective dose (BED) rather than the physical dose (PD) in treatment plan evaluation and optimization due to its stronger correlation with radiobiological effects. Radiotherapy patients may receive treatments involving a single only phase or multiple phases (e.g., primary and boost). Since most treatment planning systems cannot calculate the analytical BED distribution in multiphase treatments, an approximate multiphase BED expression, which is based on the total physical dose distribution, has been used. The purpose of this paper is to reveal the mathematical properties of the approximate BED formulation, relative to the true BED. Methods: The mathematical properties of the approximate multiphase BED equation are analyzed and evaluated. In order to better understand the accuracy of the approximate multiphase BED equation, the true multiphase BED equation was derived and the mathematical differences between the true and approximate multiphase BED equations were determined. The magnitude of its inaccuracies under common clinical circumstances was also studied. All calculations were performed on a voxel-by-voxel basis using the three-dimensional dose matrices. Results: Results showed that the approximate multiphase BED equation is accurate only when the dose-per-fractions (DPFs) in both the first and second phases are equal, which occur when the dose distribution does not significantly change between the phases. In the case of heterogeneous dose distributions, which significantly vary between the phases, there are fewer occurrences of equal DPFs and hence the inaccuracy of the approximate multiphase BED is greater. These characteristics are usually seen in the dose distributions being delivered to organs at risk rather than to targets. Conclusions: The finding of this study indicates that the true multiphase BED equation should be implemented in the treatment planning

  6. Influence of Ordovician carbonate reservoir beds in Tarim Basin by faulting

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The quality of the Ordovician carbonate reservoir beds in the Tarim Basin is closely related to the development of secondary pores,fractures and cavities. Karstification is important in improving the properties of reservoir beds,and karstification related to unconformity has caught wide attention. Compared with the recent research on the unconformity karst reservoir bed improvement,this paper shows a new way of carbonate reservoir bed transformation. Based on field survey,core and slices observation,transformation of Ordovician carbonate reservoir beds by faulting can be classified into three types: (1) Secondary faults and fracturs generated by faulting improved carbonate reservoir bed properties,which were named the Lunnan or Tazhong82 model; (2) upflow of deep geothermal fluids caused by faulting,with some components metasomatizing with carbonate and forming some secon-dary deposit,such as fluorite. It can improve carbonate reservoir bed properties obviously and is named the Tazhong 82 model; and (3) the faulting extending up to the surface increased the depth of supergene karstification and the thickness of reservoir bed. It is named the Hetianhe model. Trans-formation effect of carbonate reservoir beds by faulting was very significant,mainly distributed on the slopes or on the edge or plunging end of the uplift.

  7. The effect of slope exposition on the growth dynamics of Larix gmelinii in permafrost conditions of Central Siberia. I. Differences in tree radial dynamics growth in the north- and south-facing slopes

    Directory of Open Access Journals (Sweden)

    А. V. Benkova

    2015-08-01

    Full Text Available This paper is devoted to revealing the distinctive characteristics of radial growth of larch trees (Larix gmelinii (Rupr. Rupr. growing in permafrost contrast conditions of the north and south facing slopes (Central Siberia, 64°19´23˝ N, 100°13´28˝ E. Even-aged larch stems regenerated after strong fire in 1899 in opposite north and south facing slopes of the hills situated on the banks of Kulingdakan stream were under study. Two sample sites at the middle part of the slopes were established. 23 model trees in the north facing slope and 13 ones in the south-facing slope were selected for dendrochronological analysis. From each tree, disks at 1.3 m height of the stems were taken. Tree ring widths were measured, comparative analysis of dynamics of radial growth in the slopes was made. In order to separate time intervals, characterized by distinctive climate impact on radial increment, sliding response functions were calculated and analyzed. Daily solar radiation for both sample sites was calculated. The results showed that solar radiation in the north-facing slope is 20 % less than that in south-facing slope. Solar radiation regime promotes intensive thickening of moss-lichen cover, so that its thickness to 2009 was nearly two times thicker than in south-facing slope. Both factors affected the worth thermal soil growth conditions in the north facing slope. The latter was responsible for narrower ring widths formation in the stems and governed higher sensitivity of the trees to air temperature in the periods of cambium reactivation, start and intensive growth.

  8. [Effects of planting system on soil and water conservation and crop output value in a sloping land of Southwest China].

    Science.gov (United States)

    Xiang, Da-Bing; Yong, Tai-Wen; Yang, Wen-Yu; Yu, Xiao-Bo; Guo, Kai

    2010-06-01

    A three-year experiment was conducted to study the effects of wheat/maize/soybean with total no-tillage and mulching (NTM), wheat/maize/soybean with part no-tillage and part mulching (PTM), wheat/maize/soybean with total tillage without mulching (TWM), and wheat/maize/ sweet potato with total tillage without mulching (TWMS) on the soil and water conservation, soil fertility, and crop output value in a sloping land of Southwest China. The average soil erosion amount and surface runoff of NTM were significantly lower than those of the other three planting systems, being 1189 kg x hm(-2) and 215 m3 x hm(-2), and 10.6% and 84.7% lower than those of TWMS, respectively. The soil organic matter, total N, available K and available N contents of NTM were increased by 15.7%, 18.2%, 55.2%, and 25.9%, respectively, being the highest among the test planting systems. PTM and TWM took the second place, and TWMS pattern had the least. NTM had the highest annual crop output value (18809 yuan x hm(-2)) and net income (12619 yuan x hm(-2)) in three years, being 2.2% -20.6% and 3.8% -32.9% higher than other three planting systems, respectively. In a word, the planting system wheat/maize/soybean was more beneficial to the water and soil conservation and the improvement of soil fertility and crop output value, compared with the traditional planting system wheat/maize/sweet potato.

  9. [Rainfall intensity effects on nutrients transport in surface runoff from farmlands in gentle slope hilly area of Taihu Lake Basin].

    Science.gov (United States)

    Li, Rui-ling; Zhang, Yong-chun; Liu, Zhuang; Zeng, Yuan; Li, Wei-xin; Zhang, Hong-ling

    2010-05-01

    To investigate the effect of rainfall on agricultural nonpoint source pollution, watershed scale experiments were conducted to study the characteristics of nutrients in surface runoff under different rainfall intensities from farmlands in gentle slope hilly areas around Taihu Lake. Rainfall intensity significantly affected N and P concentrations in runoff. Rainfall intensity was positively related to TP, PO4(3-) -P and NH4+ -N event mean concentrations(EMC). However, this study have found the EMC of TN and NO3- -N to be positively related to rainfall intensity under light rain and negatively related to rainfall intensity under heavy rain. TN and TP site mean amounts (SMA) in runoff were positively related to rainfall intensity and were 1.91, 311.83, 127.65, 731.69 g/hm2 and 0.04, 7.77, 2.99, 32.02 g/hm2 with rainfall applied under light rain, moderate rain, heavy rain and rainstorm respectively. N in runoff was mainly NO3- -N and NH4+ -N and was primarily in dissolved form from Meilin soils. Dissolved P (DP) was the dominant form of TP under light rain, but particulate P (PP) mass loss increased with the increase of rainfall intensity and to be the dominant form when the rainfall intensity reaches rainstorm. Single relationships were used to describe the dependence of TN and TP mass losses in runoff on rainfall, maximum rainfall intensity, average rainfall intensity and rainfall duration respectively. The results showed a significant positive correlation between TN mass loss and rainfall, maximum rainfall intensity respectively (p rainfall, maximum rainfall intensity respectively (p < 0.01).

  10. Effect of plastic tarps over raised-beds and potassium thiosulfate in furrows on chloropicrin emissions from drip fumigated fields.

    Science.gov (United States)

    Qin, Ruijun; Gao, Suduan; McDonald, Jason A; Ajwa, Husein; Shem-Tov, Shachar; Sullivan, David A

    2008-06-01

    Plastic tarps are commonly used in raised bed strawberry production to minimize emissions of preplant soil fumigants and are left in place throughout the growing season as part of the standard cultural practices. Soil amendments with chemicals such as thiosulfate (S2O3(2-)) can reduce fumigant emissions. A field study was conducted near Santa Maria, CA to determine the effects of low density polyethylene (LDPE) and virtually impermeable film (VIF) over raised-beds and applying potassium thiosulfate (KTS) in furrows on reducing chloropicrin (CP) emissions from a strawberry field. Four fields (or treatments) were tested with 224 kg ha(-1) CP drip-applied threecm under the soil surface. The CP flux from bed tops and furrows and gas-phase concentrations under the tarps were monitored for five d. The CP emission flux and concentration under tarp were highest immediately following application. Diurnal temperature change affected CP concentration and emission fluxes (higher values during the day and lower at night). Slightly higher CP cumulative emission occurred using LDPE tarp (19%) compared to VIF (17%). Normalized flux (CP emission flux from the beds divided by CP concentration under the tarp) being estimated from field measurement was slightly higher for LDPE than VIF indicating different tarp permeability in the field. Because of extremely low emissions from the furrows (emission loss), KTS application to furrow treatments did not show further emission reductions than non-KTS treatments. This indicates that emission reduction should focus on the tarp above raised-beds when fumigant was drip-applied near bed-surface.

  11. Effect of Operating Conditions on Catalytic Gasification of Bamboo in a Fluidized Bed

    Directory of Open Access Journals (Sweden)

    Thanasit Wongsiriamnuay

    2013-01-01

    Full Text Available Catalytic gasification of bamboo in a laboratory-scale, fluidized bed reactor was investigated. Experiments were performed to determine the effects of reactor temperature (400, 500, and 600°C, gasifying medium (air and air/steam, and catalyst to biomass ratio (0 : 1, 1 : 1, and 1.5 : 1 on product gas composition, H2/CO ratio, carbon conversion efficiency, heating value, and tar conversion. From the results obtained, it was shown that at 400°C with air/steam gasification, maximum hydrogen content of 16.5% v/v, carbon conversion efficiency of 98.5%, and tar conversion of 80% were obtained. The presence of catalyst was found to promote the tar reforming reaction and resulted in improvement of heating value, carbon conversion efficiency, and gas yield due to increases in H2, CO, and CH4. The presence of steam and dolomite had an effect on the increasing of tar conversion.

  12. Effects of fluidized bed drying on the quality of soybean kernels

    Directory of Open Access Journals (Sweden)

    Hosain Darvishi

    2015-06-01

    Full Text Available The effects of air temperature and velocity on the drying qualities (cracking, bulk density, shrinkage and rehydration of soybean kernels in fluidized bed dryer were investigated. Drying was carried out at 80, 100, 120 and 140 °C and air velocity of 1.8, 3.1 and 4.5 m/s. Soybean kernels were dehydrated from the initial moisture content of 25% (w.b to a final moisture content of 10%. The drying evaluation showed that high drying temperature and air velocity resulted in high cracking and low rehydration ratios (P < 0.05. However, air velocity had no significant effect on bulk density and shrinkage of soybeans. By increasing the temperature and air velocity over their full ranges, drying time decreased from 380 to 50 min. Cracking, bulk density, degree of shrinkage and rehydration ratio varied from 31.80% to 58.22%, 1101.31 to 1186.39 kg/m3, 0.730 to 0.787, and 0.583 to 0.873, respectively. Regression equations were established which can be used for the estimation of the quality parameters as a function of the drying variables.

  13. The Artificial Gravity Bed Rest Pilot Project: Effects on Knee Extensor and Plantar Flexor Muscle Groups

    Science.gov (United States)

    Caiozzo, V. J.; Haddad, F.; Lee, S.; Baker, M.; Baldwin, K. M.

    2007-01-01

    The goal of this project was to examine the effects of artificial gravity (2.5 g) on skeletal muscle strength and key anabolic/catabolic markers known to regulate muscle mass. Two groups of subjects were selected for study: 1) a 21 day-bed rest (BR) control (C) group (N=7); and 2) an AG group (N=8), which was exposed to 21 days of bed-rest plus daily 1 hr exposures to AG (2.5 g). This particular experiment was part of an integrated AG Pilot Project sponsored by NASA/Johnson Space Center. The in vivo torque-velocity relationships of the knee extensors and plantar flexors of the ankle were determined pre and post treatment. Also, pre- and post treatment biopsy samples were obtained from both the vastus lateralis and soleus muscles and were used, in part, for a series of analyses on gene expression (mRNA abundance) of key factors implicated in the anabolic versus catabolic state of the muscle. Post/Pre toque-velocity determinations revealed greater decrements in knee extensor performance in the C versus AG group (P less than 0.04). The plantar flexor muscle group of the AG subjects actually demonstrated a net gain in torque-velocity relationship; whereas, in the C group the overall post/pre responses declined (AG vs C; P less than 0.001). Measurements of muscle fiber cross-sectional area (for both muscles) demonstrated a loss of approx. 20% in the C group while no losses were evident in the AG group. RT-PCR analyses of muscle biopsy specimens demonstrated that markers of growth and cytoskeletal integrity (IGF-1, IGF-1 BP4, mechano growth factor, total RNA, and pro-collagen 3a) were higher in the AG group, whereas catabolic markers (myostatin and atrogen) were elevated in the C group. Importantly, these patterns were seen in both muscles. Based on these observations we conclude that paradigms of AG have the potential to maintain the functional, biochemical, and structural homeostasis of skeletal muscle in the face of chronic unloading states. These findings also

  14. Effect of particle distribution on the compaction behavior of granular beds

    Science.gov (United States)

    Lowe, C. A.; Longbottom, A. W.

    2006-06-01

    This research determines how particle size and particle distribution affects the compaction of granular beds. A modelling and experimental effort was recently designed to compare the compaction behavior of two types of granular HMX: prepressed conventional (coarse) HMX material (mean diameter of 40μm) and microfine HMX (mean diameter Journal of Applied Physics 97, 093521 (2005)]. The microfine material demonstrated higher levels of granular bed strength. Mesoscale modelling of granular beds that are of fixed initial solid volume fraction but vary in particle size and distribution have been undertaken that include a simple elastic-plastic strength model. These suggest that it is not inherently the "size" of a particle that controls the bed strength but the morphology and distribution of particle grains. These solutions are compared with the behavior predicted from continuum scale models of material compaction.

  15. Branched-chain amino acid supplementation during bed rest: effect on recovery

    Science.gov (United States)

    Stein, T. P.; Donaldson, M. R.; Leskiw, M. J.; Schluter, M. D.; Baggett, D. W.; Boden, G.

    2003-01-01

    Bed rest is associated with a loss of protein from the weight-bearing muscle. The objectives of this study are to determine whether increasing dietary branched-chain amino acids (BCAAs) during bed rest improves the anabolic response after bed rest. The study consisted of a 1-day ambulatory period, 14 days of bed rest, and a 4-day recovery period. During bed rest, dietary intake was supplemented with either 30 mmol/day each of glycine, serine, and alanine (group 1) or with 30 mmol/day each of the three BCAAs (group 2). Whole body protein synthesis was determined with U-(15)N-labeled amino acids, muscle, and selected plasma protein synthesis with l-[(2)H(5)]phenylalanine. Total glucose production and gluconeogenesis from alanine were determined with l-[U-(13)C(3)]alanine and [6,6-(2)H(2)]glucose. During bed rest, nitrogen (N) retention was greater with BCAA feeding (56 +/- 6 vs. 26 +/- 12 mg N. kg(-1). day(-1), P BCAA supplementation on either whole body, muscle, or plasma protein synthesis or the rate of 3-MeH excretion. Muscle tissue free amino acid concentrations were increased during bed rest with BCAA (0.214 +/- 0.066 vs. 0.088 +/- 0.12 nmol/mg protein, P BCAA group in the recovery phase. In conclusion, the improved N retention during bed rest is due, at least in part, to accretion of amino acids in the tissue free amino acid pools. The amount accreted is not enough to impact protein kinetics in the recovery phase but does improve N retention by providing additional essential amino acids in the early recovery phase.

  16. Effects of age and inactivity due to prolonged bed rest on atrophy of trunk muscles.

    Science.gov (United States)

    Ikezoe, Tome; Mori, Natsuko; Nakamura, Masatoshi; Ichihashi, Noriaki

    2012-01-01

    This study investigated the effects of age and inactivity due to being chronically bedridden on atrophy of trunk muscles. The subjects comprised 33 young women (young group) and 41 elderly women who resided in nursing homes or chronic care institutions. The elderly subjects were divided into two groups: independent elderly group who were able to perform activities of daily living involving walking independently (n = 28) and dependent elderly group who were chronically bedridden (n = 13). The thickness of the following six trunk muscles was measured by B-mode ultrasound: the rectus abdominis, external oblique, internal oblique, transversus abdominis, thoracic erector spinae (longissimus) and lumbar multifidus muscles. All muscles except for the transversus abdominis and lumbar multifidus muscles were significantly thinner in the independent elderly group compared with those in the young group. The thicknesses of all muscles in the dependent elderly group was significantly smaller than that in the young group, whereas there were no differences between the dependent elderly and independent elderly groups in the muscle thicknesses of the rectus abdominis and internal oblique muscles. In conclusion, our results suggest that: (1) age-related atrophy compared with young women was less in the deep antigravity trunk muscles than the superficial muscles in the independent elderly women; (2) atrophy associated with chronic bed rest was more marked in the antigravity muscles, such as the back and transversus abdominis.

  17. Air effects on subharmonic bifurcations of impact in vertically vibrated granular beds

    Science.gov (United States)

    Jiang, Z. H.; Han, H.; Zhang, R.; Li, X. R.

    2013-06-01

    Experiments have been performed to investigate the effects of interstitial air on the impact bifurcations in vertically vibrated granular beds. The impact of particles on the container bottom commonly undergoes a series of subharmonic bifurcations in the sequence of period-2, period-4, chaos, period-3, period-6, chaos, period-4, period-8, and so on. In the container with an air impermeable bottom, air flows are induced and air drag on the particles causes the bifurcations to be dependent on the particle size; the bifurcation point increases with the decreasing of particle size. This makes the higher-order bifurcations become unobservable when the particle size is sufficiently small. Meanwhile, such bifurcations are shown to be controlled by both the normalized vibration acceleration and the vibration frequency. However, in the container with an air permeable bottom the size dependence of bifurcations is cancelled, and the bifurcations turn to be controlled solely by the normalized vibration acceleration. The observed results are explained in terms of an inelastic bouncing ball model with air dragging terms involved.

  18. Effect of hydraulic retention time on metal precipitation in sulfate reducing inverse fluidized bed reactors

    KAUST Repository

    Villa-Gómez, Denys Kristalia

    2014-02-13

    BACKGROUND: Metal sulfide recovery in sulfate reducing bioreactors is a challenge due to the formation of small precipitates with poor settling properties. The size of the metal sulfide precipitates with the change in operational parameters such as pH, sulfide concentration and reactor configuration has been previously studied. The effect of the hydraulic retention time (HRT) on the metal precipitate characteristics such as particle size for settling has not yet been addressed. RESULTS: The change in size of the metal (Cu, Zn, Pb and Cd) sulfide precipitates as a function of the HRT was studied in two sulfate reducing inversed fluidized bed (IFB) reactors operating at different chemical oxygen demand concentrations to produce high and low sulfide concentrations. The decrease of the HRT from 24 to 9h in both IFB reactors affected the contact time of the precipitates formed, thus making differences in aggregation and particle growth regardless of the differences in sulfide concentration. Further HRT decrease to 4.5h affected the sulfate reducing activity for sulfide production and hence, the supersaturation level and solid phase speciation. Metal sulfide precipitates affected the sulfate reducing activity and community in the biofilm, probably because of the stronger local supersaturation causing metal sulfides accumulation in the biofilm. CONCLUSIONS: This study shows that the HRT is an important factor determining the size and thus the settling rate of the metal sulfides formed in bioreactors.

  19. Effects of mass transfer and hydrogen pressure on the fixed-bed pyrolysis of sunflower bagasse

    Energy Technology Data Exchange (ETDEWEB)

    Putun, E.; Kockar, O.M.; Gercel, F. [Anadolu Univ., Eskisehir (Turkey)] [and others

    1994-12-31

    There are a number of waste and biomass sources being considered as potential sources of fuels and chemical feedstocks. The economics for biomass pyrolysis are generally considered to be most favourable for (1) plants which grow abundantly and require little cultivation in and lands and (2) wastes available in relatively large quantities from agricultural plants, for example, sunflower and hazel nuts. For the former, one such group of plants is Euphorbiaceae which are characterised by their ability to produce a milky latex, an emulsion of about 30% w/w terpenoids in water. One species in the family, Euphorbia Rigida from Southwestern Anatolia, Turkey is cultivated in close proximity to the sunflower growing regions and their oil extraction plants. The Turkish sunflower oil industry generates 800,000 tons of extraction residue (bagasse) per annum. Thus, both sunflower wastes and latex-producing plants are being considered as feedstocks for a future thermochemical demonstration unit in Turkey. Pyrolysis at relatively high hydrogen pressures (hydropyrolysis) has not been widely investigated for biomass. A potential advantage of hydropyrolysis is the ability to upgrade tar vapours over hydroprocessing catalysts. Fixed-bed pyrolysis and hydropyrolysis experiments have been conducted on sunflower bagasse to assess the effects of mass transfer and hydrogen pressure on oil yield and quality.

  20. Effect of Liquid Viscosity and Solid Inventory on Hydrodynamics in a Liquid - solid Circulating Fluidized Bed

    Directory of Open Access Journals (Sweden)

    Nirmala sundaram

    2017-01-01

    Full Text Available A comprehensive hydrodynamic study of a Liquid - Solid Circulating Fluidized Bed (LSCFB is conducted with changes in viscosity of the fluidizing medium and the inventory height of solids initially fed into the system. An LSCFB of height 2.95m and riser outer diameter 0.1m was chosen for experimentation. The three liquid media systems with varying viscosities that were chosen were water, glycerol 10% (v/v and glycerol 20% (v/v. Effect of inventory on the hydrodynamics was also studied, by taking initial heights of inventory to be 15cm, 25cm and 35cm. The hydrodynamic studies concentrated on pressure gradients along the axial pressure tapings, axial solid holdup, average solid holdup, solid circulation rate and slip velocity. Uniformity in axial solid holdup and average solid holdup was validated for changes in viscosity and inventory. Solid flux was seen to follow an inverse relationship to holdup. The changes in slip velocity with varying viscosity and inventory were studied, and found to decrease with both variables. The distribution parameter, Co of the drift flux model was found to be in the range of 0.983-0.994, suggesting non-uniformity in radial solid distribution, with higher solid concentration by the walls compared to the core of the column.

  1. Effects of a malfunctional column on conventional and FeedCol-simulated moving bed chromatography performance.

    Science.gov (United States)

    Song, Ji-Yeon; Oh, Donghoon; Lee, Chang-Ha

    2015-07-17

    The effects of a malfunctional column on the performance of a simulated moving bed (SMB) process were studied experimentally and theoretically. The experimental results of conventional four-zone SMB (2-2-2-2 configuration) and FeedCol operation (2-2-2-2 configuration with one feed column) with one malfunctional column were compared with simulation results of the corresponding SMB processes with a normal column configuration. The malfunctional column in SMB processes significantly deteriorated raffinate purity. However, the extract purity was equivalent or slightly improved compared with the corresponding normal SMB operation because the complete separation zone of the malfunctional column moved to a lower flow rate range in zones II and III. With the malfunctional column configuration, FeedCol operation gave better experimental performance (up to 7%) than conventional SMB operation because controlling product purity with FeedCol operation was more flexible through the use of two additional operating variables, injection time and injection length. Thus, compared with conventional SMB separation, extract with equivalent or slightly better purity could be produced from FeedCol operation even with a malfunctional column, while minimizing the decrease in raffinate purity (less than 2%).

  2. Effect of substrate concentration on dark fermentation hydrogen production using an anaerobic fluidized bed reactor.

    Science.gov (United States)

    de Amorim, Eduardo Lucena Cavalcante; Sader, Leandro Takano; Silva, Edson Luiz

    2012-03-01

    The effect of substrate (glucose) concentration on the stability and yield of a continuous fermentative process that produces hydrogen was studied. Four anaerobic fluidized bed reactors (AFBRs) were operated with a hydraulic retention time (HRT) from 1 to 8 h and an influent glucose concentration from 2 to 25 g L(-1). The reactors were inoculated with thermally pre-treated anaerobic sludge and operated at a temperature of 30 °C with an influent pH around 5.5 and an effluent pH of about 3.5. The AFBRs with a HRT of 2 h and a feed strength of 2, 4, and 10 g L(-1) showed satisfactory H(2) production performance, but the reactor fed with 25 g L(-1) of glucose did not. The highest hydrogen yield value was obtained in the reactor with a glucose concentration of 2 g L(-1) when it was operated at a HRT of 2 h. The maximum hydrogen production rate value was achieved in the reactor with a HRT of 1 h and a feed strength of 10 g L(-1). The AFBRs operated with glucose concentrations of 2 and 4 g L(-1) produced greater amounts of acetic and butyric acids, while AFBRs with higher glucose concentrations produced a greater amount of solvents.

  3. Effects of Slope on Land Use/Land Cover Change%坡度对土地利用/覆被变化的影响研究

    Institute of Scientific and Technical Information of China (English)

    胡荣明; 李锐; 郭斌; 文雯

    2011-01-01

    为了研究坡度因素对土地利用/覆被分布及其动态变化的影响,以陕西省西安市长安区为研究区,采用数字高程模型、遥感影像及相关辅助数据,应用GIS手段提供的空间分析方法,将长安区地形进行坡度分级,把两个不同时期的遥感影像解译结果与坡度分级图进行了空间叠加分析。研究结果表明,耕地、建筑用地、水域等分布在坡度较小范围,林地、草地的坡度分布范围近似于正态分布。不同年份各土地利用类型在相同坡度所占面积比例基本不变;不同坡度范围内的土地利用变化不尽相同。其它土地类型向耕地和建筑用地的转化主要集中在低坡度范围内,而其它土地类型向林地和草地的转化在整个坡度范围上大体呈正态分布。因此,坡度因素是土地利用/土地覆被的重要影响因素,坡度因素对土地利用格局具有明显的控制作用。%In order to study the effects of slope on land use/land cover distribution and its dynamic change,taking Chang′an District of Xi′an City,Shaanxi Province as a case study area,classified the slope derived from the digital elevation model,and then a spatial overlay analysis has been done for slope map and land use map derived from remote sensing maps.The results showed that cultivated field,construction land,water mainly distributed in areas with slight slope,and woodland,grassland distribution on slope showed a normal distribution.The percentage of different land use types in same slope area was essentially same in different years while different land-use change existed in different slopes.The conversion of other land use types to construction land and the farmland mainly occurred in the slight slope area while the conversion to forest and grassland showed a normal distribution in the whole range of slope.The slope is an important factor to land use/land cover distribution and land use pattern.

  4. Numerical simulation of flow and bed morphology in the case of dam break floods with vegetation effect

    Institute of Scientific and Technical Information of China (English)

    姜恒志; 张明亮; 许媛媛; 乔洋; 张钟哲; 张国胜

    2016-01-01

    The purpose of this study is to establish a depth-averaged 2-D hydrodynamic and sediment transport model for the dam- break flows with vegetation effect. The generalized shallow water equations are solved using an explicit finite volume method with unstructured quadtree rectangular grid, and in the hydrodynamic model, a Harten-Lax-Van Leer (HLL) approximate Riemann solver is used to calculate the intercell flux for capturing the dry-to-wet moving boundary. The sediment transport and bed variation equations in a coupled fashion are calculated by including the bed variation and the variable flow density in the flow continuity and momentum equations. The drag force of vegetation is modeled as the sink terms in the momentum equations. The developed model is tested against lab experiments of the dam-break flows over a fix bed and a movable bed in vegetated and non-vegetated channels. The results are compared with experimental data, and good agreement is obtained. It is shown that the reduced velocity under vegetated conditions leads to a decrease of the peak discharge and a rise of the water level of rivers and also an enhancement of the sediment deposition.

  5. LBNP/ergometer effects on female cardiovascular and muscle deconditioning in 15d head-down bed rest

    Science.gov (United States)

    Wang, Lin-Jie

    2012-07-01

    Female has already been an important part of astronaut corps but gender characteristics in weightlessness and countermeasure effects still not clearly elucidated. In this study the LBNP/Ergometer effects on female cardiovascular deconditioning and muscle atrophy in 15d head-down bed rest were explored. 22 female university students were recruited as volunteers that participated in the 15d head-down bed rest. They were divided into control group (Con,n=8), LBNP exercise group (LBNP,n=7) and LBNP combined with ergometer exercise group (LBNP+Ergo, n=7). Grade negative pressures of -10,-20,-30,-40mmHg 20 or 55min were used in LBNP exercise. In ergometer exercises the subjects must maintain 60-80% VO2peak of pre-bed rest at pedal speed of about 70cycle/min for 15min and the entire exercise duration was 30min. LBNP were performed at 6th,8th,10th,12th,and 13th day and Ergometer were operated at 4th,5th,7th,9th,11th day during bed rest. Before and after bed rest, cardiovascular tilt test were performed to evaluate orthostatic intolerance, supine cycle ergometer were used to test the cardiopulmonary function, MRI tests were operated to examine the volume variations of leg muscle groups and isokinetic test were given to test the muscle strength and endurance of knee. 40% of female subjects did not pass the tilt table test after bed rest and exercises made no difference. Compared with pre-BR, VO2max and VO2max /body weight, VO2/HRmax, maximal power and duration significantly decreased in CON group and LBNP group. For the ERGO+LBNP group, there were no visible different in the parameters of cardiopulmonary function except that maximal power and duration decreased. Muscle maximal voluntary contraction and muscle (quadriceps, rectus femoris, gastrocnemius and soleus) volume decreasing in non-predominant leg was larger in Con group than in LBNP+Ergo group. It is suggested that LBNP combined with ergometer in some degrees can counteract the cardiovascular and muscle deconditioning

  6. Net phytoplankton and zooplankton in the New York Bight, January 1976 to February 1978, with comments on the effects of wind, Gulf Stream eddies, and slope water intrusions

    OpenAIRE

    Smith, Daniel E.; Jossi, Jack W.

    1984-01-01

    Results are given of monthly net phytoplankton and zooplankton sampling from a 10 m depth in shelf, slope, and Gulf Stream eddy water along a transect running southeastward from Ambrose Light, New York, in 1976, 1977, and early 1978. Plankton abundance and temperature at 10 m and sea surface salinity at each station are listed. The effects of atmospheric forcing and Gulf Stream eddies on plankton distribution and abundance arc discussed. The frequency of Gulf Stream eddy passage through the N...

  7. The effects of railway transportation on the enrichment of heavy metals in the artificial soil on railway cut slopes.

    Science.gov (United States)

    Chen, Zhaoqiong; Wang, KeXiu; Ai, Ying Wei; Li, Wei; Gao, Hongying; Fang, Chen

    2014-02-01

    Heavy metal contamination in the artificial soils on the railway cut slopes may have great influence on the revegetation of the cut slopes. The purpose of this study was to assess the variation of heavy metal contamination levels with railway operation time and analyze their possible resources. A total of 100 soil samples from four cut slopes, which were affected by railway transportation for different years, were analyzed for metal pollution (Cd, Pb, Cr, Cu, Zn, Fe). The concentrations of Cd, Pb showed increasing trend with increasing operation time of railways, while such trend was not found in Cr, Cu, Zn, Fe. According to the soil quality standard of China, Cd was considered to have considerable contamination, while Pb has less, but Cr, Cu, Zn, Fe have none. Moreover, cadmium exhibited remarkably higher levels rather than those reported in other studies. Enrichment factors and ecological index showed that Cd and Pb showed a moderate enrichment and a considerable ecological risk in most of the soil samples. The results of descriptive statistic, principal component analysis, cluster analysis and correlation analysis were totally consistent with each other. Their results revealed that Cr, Cu, Zn and Fe had common origins, and they may come from natural resources. While Cd and Pb were significantly influenced by railway transportation, leaked cargos, fuel combustion, the use of lubricate oils and sleeper impregnation oils during railway transportation may be their main resources.

  8. Nitrification of an industrial wastewater in a moving-bed biofilm reactor: effect of salt concentration.

    Science.gov (United States)

    Vendramel, Simone; Dezotti, Marcia; Sant'Anna, Geraldo L

    2011-01-01

    Nitrification of wastewaters from chemical industries can pose some challenges due to the presence of inhibitory compounds. Some wastewaters, besides their organic complexity present variable levels of salt concentration. In order to investigate the effect of salt (NaCl) content on the nitrification of a conventional biologically treated industrial wastewater, a bench scale moving-bed biofilm reactor was operated on a sequencing batch mode. The wastewater presenting a chloride content of 0.05 g l(-1) was supplemented with NaCl up to 12 g Cl(-) l(-1). The reactor operation cycle was: filling (5 min), aeration (12 or 24h), settling (5 min) and drawing (5 min). Each experimental run was conducted for 3 to 6 months to address problems related to the inherent wastewater variability and process stabilization. A PLC system assured automatic operation and control of the pertinent process variables. Data obtained from selected batch experiments were adjusted by a kinetic model, which considered ammonia, nitrite and nitrate variations. The average performance results indicated that nitrification efficiency was not influenced by chloride content in the range of 0.05 to 6 g Cl(-) l(-1) and remained around 90%. When the chloride content was 12 g Cl(-) l(-1), a significant drop in the nitrification efficiency was observed, even operating with a reaction period of 24 h. Also, a negative effect of the wastewater organic matter content on nitrification efficiency was observed, which was probably caused by growth of heterotrophs in detriment of autotrophs and nitrification inhibition by residual chemicals.

  9. Effects of slope plate variable and reheating on semi-solid structure of reheating on semi-solid structure of ductile cast iron

    Directory of Open Access Journals (Sweden)

    M. Nili-Ahmadabadi

    2008-02-01

    Full Text Available Semi-solid metal casting and forming are known as a promising process for a wide range of metal alloys production. In spite of growing application of semi-solid processed light alloys, a few works have been reported about semi-solid processing of iron and steel. In this research inclined plate was used to change dendritic structure of iron to globular one. The effects of length and slope of plate on the casting structure were examined. The results show that the process can effectively change the dendritic structure to globular. In the slope plate angle of 7.5° and length of 560 mm with cooling rate of 67Ks-1 the optimum nodular graphite and solid globular particle were achieved.The results also show that by using slope plate inoculant fading can be prevented more easily since the total time of process is rather short. In addition, the semi-solid ductile cast iron prepared by inclined plate method, was reheated to examine the effect of reheating conditions on the microstructure and coarsening kinetics of the alloy. Solid fraction at different reheating temperatures and holding time was obtained and based on these results the optimum reheating temperature range was determined.

  10. A three-dimensional k-ε-kp model in curvilinear coordinates for sediment movement and bed evolution

    Institute of Scientific and Technical Information of China (English)

    SHEN YongMing; LIU Cheng

    2009-01-01

    To aim at the substitution of the magnitude and direction of water flow movement near bed for those of bed load transport in solid-liquid two-phase one-fluid model, and to simulate the effect of secondary flow on transverse bed load transport in channel bends and the effect of bed slope on bed load transport in a better way, a three-dimensional k-ε-kp solid-liquid two-phase two-fluid model in curvilinear coordinates is solved numerically with a finite-volume method on an adaptive grid for studying water-sediment movements and bed evolution in a 120° channel bend. Numerical results show that the trajectories of solid-phase deviate from those of liquid-phase in the channel bend, and the deviation increases with the increase of the particle diameters. The calculated bed deformation by the k-ε-kpmodel is in better agreement with measured bed deformation than those by one-fluid model. It is proved that the k-ε-kp model can simulate the effect of secondary flow on lateral bed load transport with the higher accuracy than the one-fluid model.

  11. A three-dimensional k-ε-k_p model in curvilinear coordinates for sediment movement and bed evolution

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    To aim at the substitution of the magnitude and direction of water flow movement near bed for those of bed load transport in solid-liquid two-phase one-fluid model, and to simulate the effect of secondary flow on transverse bed load transport in channel bends and the effect of bed slope on bed load trans- port in a better way, a three-dimensional k-ε-kp solid-liquid two-phase two-fluid model in curvilinear coordinates is solved numerically with a finite-volume method on an adaptive grid for studying wa- ter-sediment movements and bed evolution in a 120° channel bend. Numerical results show that the trajectories of solid-phase deviate from those of liquid-phase in the channel bend, and the deviation increases with the increase of the particle diameters. The calculated bed deformation by the k-ε-kp model is in better agreement with measured bed deformation than those by one-fluid model. It is proved that the k-ε-kp model can simulate the effect of secondary flow on lateral bed load transport with the higher accuracy than the one-fluid model.

  12. Stratification effects on flow field and bed topography in meandering rivers

    Science.gov (United States)

    Bolla Pittaluga, M.

    2010-12-01

    and eddy diffusivity, enhances significantly the vertical distribution of lateral velocity. Next, we investigate whether the point bar pattern in the inner bank and pool in the outer bank typically observed in meandering rivers may be significantly affected by the stratification effect. With the help of the Exner equation we show that, in the ideal case analyzed here, namely a uniform and steady flow in a constant curvature channel, stratification gives rise to steeper lateral bed profiles with respect to the unstratified case.

  13. Effects of ulvoid (Ulva spp.) accumulation on the structure and function of eelgrass (Zostera marina L.) bed

    Energy Technology Data Exchange (ETDEWEB)

    Sugimoto, Kenji [Hiroshima Environment and Health Association, 9-11, Hirosekitamachi Naka-ku, Hiroshima 730-8631 (Japan)], E-mail: kenji.sugimoto@kanhokyo.or.jp; Hiraoka, Kiyonori [Hiroshima Environment and Health Association, 9-11, Hirosekitamachi Naka-ku, Hiroshima 730-8631 (Japan); Ohta, Seiji [Hiroshima Defense Facilities Administration Bureau, 6-30, Kamihattyobori, Naka-ku, Hiroshima 730-0012 (Japan); Niimura, Yoko [National Research Institute of Fisheries and Environment of Inland Sea, 2-17-5 Maruishi Ohno, Saeki, Hiroshima 739-0452 (Japan); Terawaki, Toshinobu [Fisheries Research Agency, Queen' s Tower-B 15F, Minato-Mirai, West, Yokohama 220-6115 (Japan); Okada, Mitsumasa [Hiroshima University, 1-4-1, Kagamiyama, Higashihiroshima 739-8527 (Japan)

    2007-10-15

    The objective of this study is to clarify the effect of ulvoid (Ulva spp.) accumulation on the structure and function of an eelgrass bed by the coast of Iwakuni, Seto Inland Sea, Japan. We monitored eelgrass shoot density and volume of ulvoid accumulation in the study site and evaluated effects of the accumulated ulvoid canopy on the percent survival, seedling density, growth rates, photosynthetic photon flux density (PPFD) and carbon contents of eelgrass. Eelgrass shoot density decreased by the accumulation of ulvoid. Also, seedling density decreased by the increase in the ulvoid volumes. Shoot density, seedling density and leaf elongation were negatively correlated with ulvoid volume. Carbon contents in eelgrass decreased by the accumulation of ulvoid (canopy height: 25 cm). These results suggest that accumulation of ulvoid bloom has significant negative impacts on the structure and function of eelgrass bed, i.e. decreases in vegetative shoot density, seedling density, shoot height and growth rate.

  14. Effects of ulvoid (Ulva spp.) accumulation on the structure and function of eelgrass (Zostera marina L.) bed.

    Science.gov (United States)

    Sugimoto, Kenji; Hiraoka, Kiyonori; Ohta, Seiji; Niimura, Yoko; Terawaki, Toshinobu; Okada, Mitsumasa

    2007-10-01

    The objective of this study is to clarify the effect of ulvoid (Ulva spp.) accumulation on the structure and function of an eelgrass bed by the coast of Iwakuni, Seto Inland Sea, Japan. We monitored eelgrass shoot density and volume of ulvoid accumulation in the study site and evaluated effects of the accumulated ulvoid canopy on the percent survival, seedling density, growth rates, photosynthetic photon flux density (PPFD) and carbon contents of eelgrass. Eelgrass shoot density decreased by the accumulation of ulvoid. Also, seedling density decreased by the increase in the ulvoid volumes. Shoot density, seedling density and leaf elongation were negatively correlated with ulvoid volume. Carbon contents in eelgrass decreased by the accumulation of ulvoid (canopy height: 25cm). These results suggest that accumulation of ulvoid bloom has significant negative impacts on the structure and function of eelgrass bed, i.e. decreases in vegetative shoot density, seedling density, shoot height and growth rate.

  15. DISSIPATION OF WAVE ENERGY ON VERY MILD SLOPE

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    This paper presents the analysis and calculation of wave attenuation when waves travel on sand bed, sand ripple bed and muddy bed, respectively. The study shows that (1) The dissipation of wave energy due to bottom percolation may be neglected on sand bed; (2) The wave attenuation due to the friction of sand ripples is one order higher than that of flat sand bed and (3) The energy loss of waves propagating on muddy bed is the largest. Then, the equivalent coefficients of friction are calculated in order to compare with the solution by the bottom-friction model. Wave attenuation are also computed by the Bingham-model and the principle of conservation of wave energy flux on very mild muddy slope. The results coincide well with the wave information from the Lianyungang Wave Observation Station. Theoretical prediction proves that the equivalent coefficients of friction strongly rely on water depth, which inerease with decreasing depth.

  16. Accelerating effect of hydroxylamine and hydrazine on nitrogen removal rate in moving bed biofilm reactor.

    Science.gov (United States)

    Zekker, Ivar; Kroon, Kristel; Rikmann, Ergo; Tenno, Toomas; Tomingas, Martin; Vabamäe, Priit; Vlaeminck, Siegfried E; Tenno, Taavo

    2012-09-01

    In biological nitrogen removal, application of the autotrophic anammox process is gaining ground worldwide. Although this field has been widely researched in last years, some aspects as the accelerating effect of putative intermediates (mainly N₂H₄ and NH₂OH) need more specific investigation. In the current study, experiments in a moving bed biofilm reactor (MBBR) and batch tests were performed to evaluate the optimum concentrations of anammox process intermediates that accelerate the autotrophic nitrogen removal and mitigate a decrease in the anammox bacteria activity using anammox (anaerobic ammonium oxidation) biomass enriched on ring-shaped biofilm carriers. Anammox biomass was previously grown on blank biofilm carriers for 450 days at moderate temperature 26.0 (±0.5) °C by using sludge reject water as seeding material. FISH analysis revealed that anammox microorganisms were located in clusters in the biofilm. With addition of 1.27 and 1.31 mg N L⁻¹ of each NH₂OH and N₂H₄, respectively, into the MBBR total nitrogen (TN) removal efficiency was rapidly restored after inhibitions by NO₂⁻. Various combinations of N₂H₄, NH₂OH, NH₄⁺, and NO₂⁻ were used as batch substrates. The highest total nitrogen (TN) removal rate with the optimum N₂H₄ concentration (4.38 mg N L⁻¹) present in these batches was 5.43 mg N g⁻¹ TSS h⁻¹, whereas equimolar concentrations of N₂H₄ and NH₂OH added together showed lower TN removal rates. Intermediates could be applied in practice to contribute to the recovery of inhibition-damaged wastewater treatment facilities using anammox technology.

  17. The Effects of Spaceflight and Head Down Tilt Bed Rest on Neurocognitive Performance: Extent, Longevity, and Neural Bases

    Science.gov (United States)

    Seidler, Rachael D.; Bloomberg, Jacob; Wood, Scott; Mulavara, Ajit; Kofman, Igor; De Dios, Yiri; Gadd, Nicole; Stepanyan, Vahagn

    2017-01-01

    Spaceflight effects on gait, balance, & manual motor control have been well studied; some evidence for cognitive deficits. Rodent cortical motor & sensory systems show neural structural alterations with spaceflight. specific Aims: Aim 1-Identify changes in brain structure, function, and network integrity as a function of head down tilt bed rest and spaceflight, and characterize their time course. Aim 2-Specify relationships between structural and functional brain changes and performance and characterize their time course.

  18. The Effects of Long Duration Bed Rest as a Spaceflight Analogue on Resting State Sensorimotor Network Functional Connectivity and Neurocognitive Performance

    Science.gov (United States)

    Cassady, K.; Koppelmans, V.; Yuan, P.; Cooke, K.; De Dios, Y.; Stepanyan, V.; Szecsy, D.; Gadd, N.; Wood, S.; Reuter-Lorenz, P.; Castenada, R. Riascos; Kofman, I.; Bloomberg, J.; Mulavara, A.; Seidler, R.

    2015-01-01

    Long duration spaceflight has been associated with detrimental alterations in human sensorimotor systems and neurocognitive performance. Prolonged exposure to a head-down tilt position during long duration bed rest can resemble several effects of the microgravity environment such as reduced sensory inputs, body unloading and increased cephalic fluid distribution. The question of whether microgravity affects other central nervous system functions such as brain functional connectivity and its relationship with neurocognitive performance is largely unknown, but of potential importance to the health and performance of astronauts both during and post-flight. The aims of the present study are 1) to identify changes in sensorimotor resting state functional connectivity that occur with extended bed rest exposure, and to characterize their recovery time course; 2) to evaluate how these neural changes correlate with neurocognitive performance. Resting-state functional magnetic resonance imaging (rsfMRI) data were collected from 17 male participants. The data were acquired through the NASA bed rest facility, located at the University of Texas Medical Branch (Galveston, TX). Participants remained in bed with their heads tilted down six degrees below their feet for 70 consecutive days. RsfMRI data were obtained at seven time points: 7 and 12 days before bed rest; 7, 50, and 65 days during bed rest; and 7 and 12 days after bed rest. Functional connectivity magnetic resonance imaging (fcMRI) analysis was performed to measure the connectivity of sensorimotor networks in the brain before, during, and post-bed rest. We found a decrease in left putamen connectivity with the pre- and post-central gyri from pre bed rest to the last day in bed rest. In addition, vestibular cortex connectivity with the posterior cingulate cortex decreased from pre to post bed rest. Furthermore, connectivity between cerebellar right superior posterior fissure and other cerebellar regions decreased from

  19. Coal-bed methane water effects on dill and essential oils

    Science.gov (United States)

    Pumping water from coal seams decreases the pressure in the seam and in turn releases trapped methane; this is the most common and economic way of methane extraction. The water that is pumped out is known as coal-bed methane water (CBMW), which is high in sodium and other salts. In past 25 years, th...

  20. Effect of sediment transport boundary conditions on the numerical modeling of bed morphodynamics

    Science.gov (United States)

    Experimental sediment transport studies in laboratory flumes can use two sediment-supply methods: an imposed feed at the upstream end or recirculation of sediment from the downstream end to the upstream end. These methods generally produce similar equilibrium bed morphology, but temporal evolution c...

  1. The effect of operational conditions on the hydrodynamic characteristics of the sludge bed in UASB reactors

    NARCIS (Netherlands)

    Leitao, R.C.; Santaellla, S.T.; Haandel, van A.C.; Zeeman, G.; Lettinga, G.

    2011-01-01

    This work aims to evaluate the hydrodynamic properties of the sludge bed of Upflow Anaerobic Sludge Blanket (UASB) reactors based on its settleability and expansion characteristics. The methodologies used for the evaluation of the settleability of aerobic activated sludge, and for the expansibility

  2. Modeling of structural effects in biomedical elements after titanium oxidation in fluidized bed

    Directory of Open Access Journals (Sweden)

    Mendzik K.

    2010-06-01

    Full Text Available Oxidation is one of the most employed methods to improve titanium and its alloys properties especially due to medical application. This process like most of the thermochemical treatment processes substantially influences on the characteristic of surface layers and the same on its mechanical and useful properties. Oxide coatings produced during titanium oxidation were examined due to their composition identification. Titanium was oxidized in fluidized bed in temperature range between 500÷700°C. Microstructures of titanium with a visible oxide coating on its surface after thermochemical treatment and changes of grain size in core of titanium samples are described. Moreover Xray phase analysis of obtained oxides coatings was made as well as microhardness measurements of titanium surface layers after oxidation process. Finally, the surfaces of titanium after oxidation in fluidized bed were measured by Auger electron spectroscopy. All research results are used to built numerical model of oxidation process in fluidized. Titanium oxidation process in fluidized bed is very complicated, because changes of parameters are non linear characteristics. This fact and lack of mathematical algorithms describing this process makes modeling properties of titanium elements by traditional numerical methods difficult or even impossible. In this case it is possible to try using artificial neural network. Using neural networks for modeling oxidizing in fluidized bed is caused by several nets' features: non linear character, ability to generalize the results of calculations for data out of training set, no need for mathematical algorithms describing influence changes input parameters on modeling materials properties.

  3. Effects of bedding material on ammonia volatilization in a broiler house

    Science.gov (United States)

    Ammonia volatilization from poultry house bedding material is a major production issues because the buildup of ammonia within the facilities is a human health issue and can negatively impact the performance of the birds. Major operational cost is associated with the ventilation of poultry houses to ...

  4. Effect of Vegetation and Precipitation upon Runoff and Sediment Production on Slope Lands of the Loess Area in China

    Institute of Scientific and Technical Information of China (English)

    WU Sihong; ZHANG Xiaoming; ZHU Qinke

    2006-01-01

    According to fixed-position data for 1992-2003 from 16 runoff plots of Caijiachuan watershed which lie in Jixian County,Shanxi Province,in the loess area,this paper studied the relationship between vegetation and runoff and sediment production on slope lands.The results showed as follows:1)Runoff and sediment production in Robinia pseudoacacia forest and Pinus tabulaeformis forest had a high correlation with precipitation amount and rainfall intensity,but the correlation decreased gradually with the increase of canopy density;2)The secondary forest had better function of soil and water conservation than artificial R.pseudoacacia forest,and runoff and sediment production in the former in an individual rain event was 65%-82% and 23%-92% lower than those in the latter,respectively;3)The difference of runoff and sediment production in several land uses was very distinct.Runoff and sediment production in Ostryopsis davidiana forest and the secondary forest were the least;runoff and sediment production in artificial R.pseudoacacia forest and P. tabulaeformis forest were 5-fold as much as those in O.davidiana forest.Besides.runoff and sediment production in mixed stand of apple trees and crops were 16.14-fold and 2.96-fold higher than that in O.davidiana forest,respectively,but the amount decreased obviously after high-standard soil preparation for the former;4)Based on gray correlation analysis of various factors affecting runoff and sediment production on slope lands,it can be seen that stand canopy density and herb and litter biomass were the most significant ones,whose gray correlation values all exceeded 0.6.Therefore.mixed forest with multi-layer stand structure and shrub forest should be developed in vegetation reconstruction of the loess area,which help to increase coverage and litter thickness to cut down the runoff and sediment production dramatically on slope lands.

  5. Effect of Various Organic Matter stimulates Bacteria and Arbuscular Mycorrhizal Fungi Plantations on Eroded Slopes in Nepal

    Science.gov (United States)

    Shrestha Vaidya, G.; Shrestha, K.; Wallander, H.

    2009-04-01

    Erosion resulting from landslides is a serious problem in mountainous countries such as Nepal. To restore such sites it is essential to establish plant cover that protects the soil and reduces erosion. Trees and shrubs on the lower hillsides in Nepal form symbiosis with arbuscular mycorrhizal (AM) fungi and these fungi are important for the uptake of mineral nutrients from the soil. In addition, the mycelia formed by these fungi have an important function in stabilizing the soil. The success of plantations of these eroded slopes is therefore highly dependent on the extent of mycorrhizal colonization of the plants. Mycorrhizal fungi growing in symbiosis with plants are essential in this respect because they improve both plant and nutrient uptake and soil structure. We investigated the influence of organic matter and P amendment on recently produced biomass of bacteria and arbuscular mycorrhizal (AM) fungi in eroded slopes in Nepal. Eroded soil mixed with different types of organic matter was placed in mesh bags which were buried around the trees of Bauhinia purpurea and Leucaena diversifolia .This experiment were done in two seasons ( (the wet and the dry season). Signature fatty acids were used to determine bacterial and AM fungal biomass after the six month intervals. The amount and composition of AM fungal spores were analyzed in the mesh bags from the wet and dry seasons. More microbial biomass was produced during wet season than during dry season. Further more, organic matter addition enhanced the production of AM fungal and bacterial biomass during both seasons. The positive influence of organic matter addition on AM fungi could be an important contribution to plant survival, growth and nutrient composition in the soil in plantations on eroded slopes. Different AM spore communities and bacterial profiles were obtained with different organic amendments and this suggests a possible way of selecting for specific microbial communities in the management of eroded

  6. Effect of contaminant concentration on aerobic microbial mineralization of DCE and VC in stream-bed sediments

    Science.gov (United States)

    Bradley, P.M.; Chapelle, F.H.

    1998-01-01

    Discharge of DCE and VC to an aerobic surface water system simultaneously represents a significant environmental concern and, potentially, a non-engineered opportunity for efficient contaminant bioremediation. The potential for bioremediation, however, depends on the ability of the stream-bed microbial community to efficiently and completely degrade DCE and VC over a range of contaminant concentrations. The purposes of the studies reported here were to assess the potential for aerobic DCE and VC mineralization by stream-bed microorganisms and to evaluate the effects of DCE and VC concentrations on the apparent rates of aerobic mineralization. Bed-sediment microorganisms indigenous to a creek, where DCE-contaminated groundwater continuously discharges, demonstrated rapid mineralization of DCE and VC under aerobic conditions. Over 8 days, the recovery of [1,2-14C]DCE radioactivity as 14CO2 ranged from 17% to 100%, and the recovery of [1,2- 14C]VC radioactivity as 14CO2 ranged from 45% to 100%. Rates of DCE and VC mineralization increased significantly with increasing contaminant concentration, and the response of apparent mineralization rates to changes in DCE and VC concentrations was adequately described by Michaelis-Menten kinetics.Discharge of DCE and VC to an aerobic surface water system simultaneously represents a significant environmental concern and, potentially, a non-engineered opportunity for efficient contaminant bioremediation. The potential for bioremediation, however, depends on the ability of the stream-bed microbial community to efficiently and completely degrade DCE and VC over a range of contaminant concentrations. The purposes of the studies reported here were to assess the potential for aerobic DCE and VC mineralization by stream-bed microorganisms and to evaluate the effects of DCE and VC concentrations on the apparent rates of aerobic mineralization. Bed-sediment microorganisms indigenous to a creek, where DCE-contaminated groundwater

  7. The effects of the mineral phase on C stabilization mechanisms and the microbial community along an eroding slope transect

    Science.gov (United States)

    Doetterl, S.; Opfergelt, S.; Cornelis, J.; Boeckx, P. F.; van oost, K.; Six, J.

    2013-12-01

    An increasing number of studies show the importance of including soil redistribution processes in understanding carbon (C) dynamics in eroding landscapes. The quality and quantity of soil organic carbon in sloping cropland differs with topographic position. These differences are commonly more visible in the subsoil, while the size and composition of topsoil C pools are similar along the hillslope. The type (plant- or microbial-derived) and quality (level of degradation) of C found in a specific soil fraction depends on the interplay between the temporal dynamic of the specific mechanism and it's strength to protect C from decomposition. Here, we present an analysis that aims to clarify the bio/geo-chemical and mineralogical components involved in stabilizing C at various depths and slope positions and how they affect the microbial community and the degradation of C. For this we analyzed soil samples from different soil depths along a slope transect applying (i) a sequential extraction of the reactive soil phase using pyrophosphate, oxalate and dithionite-citrate-bicarbonate, (ii) a semi-quantitative and qualitative analysis of the clay mineralogy, (iii) an analysis of the microbial community using amino sugars and (iv) an analysis of the level of degradation of C in different soil fractions focusing on the soil Lignin signature. The results show that the pattern of minerals and their relative importance in stabilizing C varies greatly along the transect. In the investigated soils, pyrophosphate extractable Manganese, and not Iron or Aluminum as often observed, is strongly correlated to C in the bulk soil and in the non-aggregated silt and clay fractions. This suggests a certain role of Manganese for C stabilization where physical protection is absent. In contrast, pyrophosphate extractable Iron and Aluminum components are largely abundant in water-stable soil aggregates but not correlated to C, suggesting importance of these extracts to stabilize aggregates and

  8. Hydrodynamic modeling of dense gas-fluidised beds using the kinetic theory of granular flow: effect of coefficient of restitution on bed dynamics

    NARCIS (Netherlands)

    Goldschmidt, M.J.V.; Kuipers, J.A.M.; Swaaij, van W.P.M.

    2000-01-01

    A two-dimensional multi-fluid Eulerian CFD model with closure laws according to the kinetic theory of granular flow has been applied to study the influence of the coefficient of restitution on the hydrodynamics of dense gas-fluidised beds. It is demonstrated that hydrodynamics of dense gas-fluidised

  9. Hydrodynamic modelling of dense gas-fluidised beds using the kinetic theory of granular flow: effect of coefficient of restitution on bed dynamics.

    NARCIS (Netherlands)

    Goldschmidt, M.J.V.; Kuipers, J.A.M.; Swaaij, van W.P.M.

    2001-01-01

    A two-dimensional multi-fluid Eulerian CFD model with closure laws according to the kinetic theory of granular flow has been applied to study the influence of the coefficient of restitution on the hydrodynamics of dense gas-fluidised beds. It is demonstrated that hydrodynamics of dense gas-fluidised

  10. 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)

    Sint Annaland, van M.; Kürten, 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 pro

  11. Study of Blasting Vibration Effect on HML Open-pit Mine Slope%爆破震动对HML露天矿边坡影响的研究

    Institute of Scientific and Technical Information of China (English)

    张建华; 黄刚

    2012-01-01

    Frequent blasting vibration could exert its influence on the stability of exiting slope of open-pit mine. Based on the study of HML open-pit mine monitors the effect of blasting vibration on the slope and obtains the formula of decay law of blasting seismic waves in rock mass with regression analysis principle. According to the formula,it can help to design the blasting parameter and predict the vibration for future. Based on the former data, the mine blasting could be simulated by the LS-DYNA explicit dynamic analysis software to analysis the effect of blasting vibration on slope. The mechanism of hazards and laws of seismic waves in the propagation of the rock mass can be concluded by analyzing the vibration speed and effective stress of dot and element from slope model in HML mining which ensures the smooth running of mine production and provides the basis to maintain the stability of the slope.%频繁的爆破震动会对露天矿已有边坡稳定性造成影响.以HML露天矿为背景,监测爆破震动对边坡的扰动,用回归分析原理得出爆破地震波在岩体中传播衰减规律公式.为今后的爆破设计和震动的预测提供依据.在原有的数据基础上,利用LS—DYNA显式动力分析软件模拟矿山爆破,分析爆破地震波对边坡的影响.在边坡模型上选取点和单元体,通过分析比较其震动速度和有效应力的衰减规律,可以总结出地震波在HML矿山岩体中的传播规律和危害机理.为确保矿山生产顺利进行,维护矿山边坡的稳定性提供依据.

  12. Effect of head-down bed rest on the neuroendocrine response to orthostatic stress in physically fit men.

    Science.gov (United States)

    Koska, J; Ksinantová, L; Kvetnanský, R; Marko, M; Hamar, D; Vigas, M; Hatala, R

    2003-01-01

    The role of neuroendocrine responsiveness in the development of orthostatic intolerance after bed rest was studied in physically fit subjects. Head-down bed-rest (HDBR, -6 degrees, 4 days) was performed in 15 men after 6 weeks of aerobic training. The standing test was performed before, after training and on day 4 of the HDBR. Orthostatic intolerance was observed in one subject before and after training. The blood pressure response after training was enhanced (mean BP increments 18+/-2 vs. 13+/- 2 mm Hg, pE.M.), although noradrenaline response was diminished (1.38+/-0.18 vs. 2.76+/-0.25 mol.l(-1), pstanding and had no effect on the orthostatic tolerance. In orthostatic intolerance the BP response induced by subsequent HDBR was absent despite an enhanced sympathetic response.

  13. EFFECTS OF NUTRIENT ENRICHMENT ON PRIMARY PRODUCTION AND BIOMASS OF SEDIMENT MICROALGAE IN A SUBTROPICAL SEAGRASS BED(1).

    Science.gov (United States)

    Bucolo, Philip; Sullivan, Michael J; Zimba, Paul V

    2008-08-01

    Eutrophication of coastal waters often leads to excessive growth of microalgal epiphytes attached to seagrass leaves; however, the effect of increased nutrient levels on sediment microalgae has not been studied within seagrass communities. A slow-release NPK Osmocote fertilizer was added to sediments within and outside beds of the shoal grass Halodule wrightii, in Big Lagoon, Perdido Key, Florida. Gross primary production (GPP) and biomass (HPLC photopigments) of sediment microalgae within and adjacent to fertilized and control H. wrightii beds were measured following two 4-week enrichment periods during June and July 2004. There was no effect of position on sediment microalgal GPP or biomass in control and enriched plots. However, nutrient enrichment significantly increased GPP in both June and July. These results suggest that sediment microalgae could fill some of the void in primary production where seagrass beds disappear due to excessive nutrient enrichment. Sedimentary chl a (proxy of total microalgal biomass) significantly increased only during the June enrichment period, whereas fucoxanthin (proxy of total diatom biomass) was not increased by nutrient enrichment even though its concentration doubled in the enriched plots in June.

  14. Effect of char preparation temperature on the evolution of nitrogen-containing species during char oxidation at fluidized bed combustion

    Energy Technology Data Exchange (ETDEWEB)

    Ren, W.; Lu, J.; Yue, G. [Tsinghua Univ., Beijing (China). Dept. of Thermal Engineering; Beer, J.M. [Massachusetts Inst. of Technology, Boston, MA (United States). Dept. of Chemical and Fuel Engineering; Molina, A.; Sarofim, A.F. [Utah Univ., Salt Lake City, UT (United States). Dept. of Chemical and Fuels Engineering

    2002-07-01

    Fluidized bed combustion is gaining popularity as a means to burn coal and waste fuels because the low temperatures of fluidized bed combustors generally result in low thermal nitric oxide (NO) production. However, nitrous oxide (N{sub 2}O) emissions can be relativity high and strategies must be developed to reduce emissions of this greenhouse gas. This paper presents the results of a laboratory study that examined the effect of pyrolysis temperature on the conversion of char-N to N{sub 2}O, NO and hydrogen cyanide (HCN) in fluidized bed combustion. When anthracite coal was used, an increase in the pyrolysis temperature resulted in reduced conversion of char-N to N{sub 2}O and HCN. However, the conversion to NO increased. This observation may be due to the lower hydrogen content of the chars produced at higher temperature and their lower reactivity. Other possibilities may be that the lower char reactivity for chars produced at high pyrolysis temperature may affect the reactions occurring in the boundary layer. Chars of lower reactivity in particular, may react at lower particle temperature and under high transient oxygen concentrations. A simplified char combustion representation was used to examine the effect of temperature and equivalence ratio on HCN oxidation. A reduction of equivalence ratio could explain some of the observed variations in product distribution with increased pyrolysis temperature. 19 refs., 1 tab., 5 figs.

  15. THE EFFECT OF THE THICKNESS OF A PACKED BED ON THE DYNAMIC AND THERMAL BEHAVIOR OF A SOLAR DRYER

    Directory of Open Access Journals (Sweden)

    S KHALDI

    2015-06-01

    Full Text Available Drying food in the sun is a safe, easy and economical way to preserve food, especially fruits. Cabinet dryers are the most popular equipment for fruit drying. Because of intermittent nature of solar energy, storage is required for uninterrupted supply in order to match the needs. The main objective of this study is to assess effectiveness of continuous solar dryer integrated with packed bed as thermal storage with natural airflow for drying figs (Ficuscarica. The cabinet dryer were envisaged theoretically (computational fluid dynamics (CFD. The distribution of the velocity and temperature of air within the solar dryer were presented during one day of August and under the climate conditions of Tlemcen (Algeria.  The effects of presence of a packed bed on the distribution of velocity and temperature of airflow and on the temperature of figs were analyzed. The results show that the solar dryer design, incorporating a packed bed enhances the capabilities and performance of the solar dryer, through increasing time of drying.

  16. Effects of erosion in the fate of soil organic carbon and soil aggregation in a burned Mediterranean hill-slope

    Science.gov (United States)

    Campo, Julian; Cammeraat, Erik; Gimeno-García, Eugenia; Andreu, Vicente

    2016-04-01

    The Intergovernmental Panel on Climate Change indicated a higher degree of confidence that meteorological conditions associated to climate change will be propitious to increasing extreme events manifested, among others, in bigger and more frequent wildfires (IPCC, 2014). Wildfires contribute to shaping the landscape, and also the geomorphological and hydrological processes that operate on soil are affected (Bento-Gonçalves et al., 2012). Whereas, it is well documented that wildfires produce significant changes on erosion processes, the associated fate of soil organic carbon (SOC) has received less attention. This research assesses this gap by studying the loss, redistribution, and stabilization of SOC in a Mediterranean forest hill-slope burned the 28-08-2014, with high severity fire, at the Natural Park of Sierra de Espadán, Spain (39°50'45.11"N, 0°22'20.52"W). To this end, soil was sampled (19-9-2014) in the foot's slope (depositional), middle part (transport) and top (eroding) at two depths (146 drops). Significant differences (ANOVA, pBS) and soil depths (topsoil>subsoil). However, no significant differences were observed among eroding (58.8+20.8 gC kg-1), transport (67.3+34.4 gC kg-1), and depositional zones (62.0+31.3 gC kg-1), which is not in agreement with other SOC redistribution studies (Wang et al., 2014). Significant differences (Kruskal-Wallis, pBS) but not between soil depths or hill-slope positions. In the first post-fire erosive rains occurred in the area (29-11-14), closest pluviometer (Sot de Ferrer: 4.5 km) registered a total daily rain up to 64.2 l m-2. In this event a total of 12.7 kg of sediment were collected (contributing area ≈0.25 ha), with a content of 252.6 gC kg-1 the total SOC transported or stored in the depositional zone can reach up to 3.2 kg. In the second erosive event (23-3-15: 103.2 l m-2), total sediment in the fences was 143.6 kg, with content of 112.2 gC kg-1, made a total SOC eroded of up to 16.1 kg. It is hypothesized

  17. Modeling the competitive effect of ammonium oxidizers and heterotrophs on the degradation of MTBE in a packed bed reactor

    DEFF Research Database (Denmark)

    Waul, Christopher Kevin; Arvin, Erik; Schmidt, Jens Ejbye

    2008-01-01

    A mathematical model was used to study effects on the degradation of methyl tert-butyl ether (MTBE) in a packed bed reactor due to the presence of contaminants such as ammonium, and the mix of benzene, toluene, ethylbenzene and xylenes (BTEX). It was shown that competition between the slower...... where the co-contaminants were oxidized. The results of the model further indicate that contradicting findings in the literature about the effects of BTEX on the degradation of MTBE are mainly due to differences in the study methodologies. Effects such as short-term toxicity of BTEX and the lack...

  18. Effects of slope plate variable and reheating on semi-solid structure of reheating on semi-solid structure of ductile cast iron

    OpenAIRE

    M. Nili-Ahmadabadi; Pahlevani, F.; P. Babaghorbani

    2008-01-01

    Semi-solid metal casting and forming are known as a promising process for a wide range of metal alloys production. In spite of growing application of semi-solid processed light alloys, a few works have been reported about semi-solid processing of iron and steel. In this research inclined plate was used to change dendritic structure of iron to globular one. The effects of length and slope of plate on the casting structure were examined. The results show that the process can effectively change ...

  19. Biological aspects and ecological effects of a bed of the invasive non-indigenous mussel Brachidontes pharaonis (Fischer P., 1870 in Malta

    Directory of Open Access Journals (Sweden)

    L. BONNICI

    2012-12-01

    Full Text Available No mussel beds were known to occur in the Maltese Islands previous to 2009, when a single bed of the Lessepsian immigrant Brachidontes pharaonis, first recorded from the islands in 1970, was discovered in Birzebbugia Bay. The population structure of B. pharaonis was investigated to assess its potential to spread and colonise new shores, while the biotic community at the mussel bed was compared to that present on uncolonised substratum to determine the effects of mussel bed establishment on the associated biota. Results indicate a lower species richness and slightly different community structure with greater small-scale heterogeneity at the mussel bed site compared to the adjacent rocky shore where mussels are present but where there is no bed formation. The B. pharaonis population had a peak density of 16550 ± 2051 ind.m-2 within the mussel bed and included recent recruits. These data suggest that the B. pharaonis population has the potential to expand. Establishment of extensive beds by this invasive mussel could change the structure of native rocky shore assemblages around the Maltese Islands and elsewhere in the Mediterranean.

  20. Effect of Slope Degree and Slope Position on Soil Nutrient Variability in the Early Succession of Rocky Slope Revegetation%坡度和坡位对岩质边坡早期生态恢复土壤养分变异性的影响

    Institute of Scientific and Technical Information of China (English)

    潘树林; 周顺涛; 辜彬

    2012-01-01

    Through the analysis on 16 rocky slopes of Zhejiang Province which had already been ecological restored for one year,in the early vegetation recovery stage when there was no interactive development between vegetation and environment on the slope,the influence of slope angle and slope position on soil nutrient variability were as follow:(1) in some rocky slopes with slope degree of 45°-52°,available P content showed consistent trends: the lower slope position〉the middle slope position〉the upper slope position,and the total N,total P,total K contents of other rocky slopes varied significantly: the middle slope position〉the lower slope position〉the upper slope position;(2) in different slope positions with similar slope degree,the total N,total K contents and organic matter had no significant differences,but soil available nutrients had showed more remarkable differences in the multiple comparisons of soil nutrients;(3) in different slope angles with the same slope position,significant differences were only found in two groups in the multiple comparisons of soil nutrients,and there was no large—scale variability of soil nutrients.In other words,in the early succession stage of rocky slope revegetation,soil nutrients wouldn′t be significantly influence by slope angle ranging from 30° to 52°.%通过对浙江省经过1a生态恢复的16个岩质边坡,在坡面没有植被和坡面环境形成交互发展的植被早期恢复进行研究,结果表明:(1)除45°~52°类型的边坡土壤有效磷含量为坡下〉坡中〉坡上外,其它3个坡度类型中全氮、全磷、全钾都呈现出较明显的坡中〉坡下〉坡上的分布规律。(2)在相似坡度及不同坡位条件下,全氮、全钾、有机质都没有表现出显著性差异。土壤养分多重比较出现较多差异的是有效态养分。(3)在相同坡位不同坡度条件下,对岩质边坡早期生态恢复的土壤养分进行多

  1. Effects of polyacrylamide on soil erosion and nutrient losses from substrate material in steep rocky slope stabilization projects.

    Science.gov (United States)

    Chen, Zhang; Chen, Wenlu; Li, Chengjun; Pu, Yanpin; Sun, Haifeng

    2016-06-01

    Erosion of denuded steep rocky slopes causes increasing losses of nitrogen and phosphorus, which is a severe problem in rocky slope protection. Thus, it is important to determine the appropriate materials that can reduce the erodibility and losses of nitrogen and phosphorus of the soil. In this paper, twenty-seven simulated rainfall events were carried out in a greenhouse, in which the substrate material was artificial soil; nine types of anionic polyacrylamide (PAM) were studied, which consisted of three molecular weight (6, 12, and 18 Mg mol(-1)) and three charge density (10, 20, and 30%) formulations in a 3 by 3 factorial design. The results showed that: (1) Polyacrylamide application reduced total nitrogen losses by 35.3% to 50.0% and total phosphorus losses by 34.9% to 48.0% relative to the control group. (2) The losses of total nitrogen and total phosphorus had significant correlation with the molecular weight. Besides, the losses of total phosphorus, particulate-bound phosphorus and inorganic nitrogen (NH4-N) were significantly correlated with their molecular weight and charge density. However, the losses of dissolved organic nitrogen, inorganic nitrogen (NO3-N), dissolved organic phosphorus, inorganic phosphorus (PO4-P) were non-significantly correlated with molecular weight and charge density. (3) Particulate-bound nitrogen and phosphorus were responsible for the losses of nitrogen and phosphorus during runoff events, where particulate-bound nitrogen made up 71.7% to 73.2% of total nitrogen losses, and particulate-bound phosphorus made up 82.3% to 85.2% of total phosphorus losses. (4) Polyacrylamide treatments increased water-stable aggregates content by 32.3% to 59.1%, total porosity by 11.3% to 49.0%, final infiltrative rate by 41.3% to 72.5%, and reduced soil erosion by 18.9% to 39.8% compared with the control group. Overall, the results of this study indicated that polyacrylamide application in the steep rocky slope stabilization projects could

  2. Effects of prolonged bed rest on the total peripheral resistance baroreflex

    Science.gov (United States)

    Xiao, X.; Mukkamala, R.; Sheynberg, N.; Williams, G. H.; Cohen, R. J.; Mark, R. G. (Principal Investigator)

    2002-01-01

    Orthostatic intolerance following prolonged exposure to microgravity continues to be a primary concern of the human space program. Reduced autonomic tone has been demonstrated to contribute to this phenomenon, and the heart rate baroreflex, in particular, has been repeatedly shown to be impaired. However, only the works of Yelle et al. have attempted to address the role of the total peripheral resistance (TPR) baroreflex, a potentially more significant contributor to blood pressure regulation. We applied a previously developed method for estimating the static gains of both the arterial and cardiopulmonary TPR baroreflexes to data obtained before and after 16-day bed rest. Reductions in the estimated static gains of the arterial (statistically significant) and cardiopulmonary TPR baroreflexes were found after bed rest. This study supports the works of Yelle et al, which imply that the TPR baroreflex is reduced after spaceflight.

  3. Development of an Effective Special Therapy Bed Management System at Walter Reed Army Medical Center.

    Science.gov (United States)

    1991-12-01

    term care of the elderly , health care providers began looking for better bed surfaces for their high risk patients. The search for a pressure relieving...immobile patients at risk for pressure sore development is the role of proper positioning by nursing personnel. The repositioning of patients every...and efficacy of air-fluidized therapy in the treatment of pressure ulcers . Journal of Enterostomal Therapy, 15(6), 247-251. Hargest, T. S., & Artz, C

  4. Effects of Starvation on Deltamethrin Tolerance in Bed Bugs, Cimex lectularius L. (Hemiptera: Cimicidae

    Directory of Open Access Journals (Sweden)

    Zachary C. DeVries

    2015-01-01

    Full Text Available Bed bugs, Cimex lectularius L., are a major pest in the urban environment. Their presence often results in physical, psychological, and financial distress of homeowners and apartment dwellers. Although many insecticide bioassays have been performed on this pest, little attention has been paid to bed bug feeding status, which is closely linked to metabolism, molting, and mass. Therefore, we evaluated the toxicity of topically applied deltamethrin on insecticide susceptible adult male bed bugs fed 2 d, 9 d, and 21 d prior to testing. When toxicity was evaluated on a “per-bug” basis, there was no difference between 2 d [LD50 = 0.498 (0.316 − 0.692 ng·bug−1] and 9 d [LD50 = 0.572 (0.436 − 0.724 ng·bug−1] starved bugs, while 21 d starved bugs had a significantly lower LD50 [0.221 (0.075 − 0.386 ng·bug−1]. When toxicity was evaluated in terms of body mass, 9 d starved bugs had the highest LD50 values [0.138 (0.102 − 0.176 ng·mg−1], followed by 2 d starved bugs [0.095 (0.060 − 0.134 ng·mg−1], and then 21 d starved bugs [0.058 (0.019–0.102 ng·mg−1]; the LD50 values of 2 d and 9 d starved bugs were significantly different from 21 d starved bugs. These results indicate that feeding status plays an important role in the toxicity of deltamethrin. In addition, the lack of differences between 2 d and 9 d starved bugs indicate that the blood meal itself has little impact on tolerance, but rather it is some physiological change following feeding that confers increased tolerance to bed bugs.

  5. Comparative analysis of CFD models for jetting fluidized beds: Effect of particle-phase viscosity

    Institute of Scientific and Technical Information of China (English)

    Pei Pei; Kai Zhang; Gang Xu; Yongping Yang; Dongsheng Wen

    2012-01-01

    Under the Eulerian-Eulerian framework of simulating gas-solid two-phase flow,the accuracy of the hydrodynamic prediction is strongly affected by the selection of rheology of the particulate phase,for which a detailed assessment is still absent.Using a jetting fluidized bed as an example,this work investigates the influence of solid theology on the hydrodynamic behavior by employing different particle-phase viscosity models.Both constant particle-phase viscosity model (CVM) with different viscosity values and a simple two-fluid model without particle-phase viscosity (NVM) are incorporated into the classical twofluid model and compared with the experimental measurements.Qualitative and quantitative results show that the jet penetration depth,jet frequency and averaged bed pressure drop are not a strong function of the particle-phase viscosity.Compared to CVM,the NVM exhibits better predictions on the jet behaviors,which is more suitable for investigating the hydrodynamics of gas-solid fluidized bed with a central jet.

  6. The Soret and Dufour Effects in Non-thermal Equilibrium Packed Beds with Forced Convection and Endothermic Reactions

    Institute of Scientific and Technical Information of China (English)

    李明春; 赵中亮; 静宇; 刘家涛; 吴玉胜

    2013-01-01

    To study the influence of the Soret and Dufour effects on the reactive characteristics of a porous packed bed with endothermic reactions and forced convection, a two-dimensional mathematical model considering the cross-diffusion effects was developed in accordance with the thermodynamics of irreversible processes and the lo-cal thermal non-equilibrium model. The simulation results were validated by comparing with experimental data. The influence of the Soret and Dufour effects on the heat transfer, mass transfer and endothermic chemical reaction in the non-thermal equilibrium packed bed is discussed. It was found that when the Peclet number reaches 1865, the maximum relative error of the concentration of gas product induced by the Soret effect is 34.7% and that of the solid fractional conversion caused by the Dufour effect is 10.8%at reaction time 160 s and initial temperature 1473 K. The differences induced by the Soret and Dufour effects are demonstrated numerically to increase gradually with the initial temperature of feeding gas and the Peclet number.

  7. Gas hydrate dissociation structures in submarine slopes

    Energy Technology Data Exchange (ETDEWEB)

    Gidley, I.; Grozic, J.L.H. [Calgary Univ., AB (Canada). Dept. of Civil Engineering

    2008-07-01

    Studies have suggested that gas hydrates may play a role in submarine slope failures. However, the mechanics surrounding such failures are poorly understood. This paper discussed experimental tests conducted on a small-scale physical model of submarine soils with hydrate inclusions. The laboratory tests investigated the effects of slope angle and depth of burial of the hydrate on gas escape structures and slope stability. Laponite was used to model the soils due to its ability to swell and produce a clear, colorless thixotropic gel when dispersed in water. An R-11 refrigerant was used to form hydrate layers and nodules. The aim of the experiment was to investigate the path of the fluid escape structures and the development of a subsequent slip plane caused by the dissociation of the R-11 hydrates. Slope angles of 5, 10, and 15 degrees were examined. Slopes were examined using high-resolution, high-speed imaging techniques. Hydrate placement and slope inclinations were varied in order to obtain stability data. Results of the study showed that slope angle influenced the direction of travel of the escaping gas, and that the depth of burial affected sensitivity to slope angle. Theoretical models developed from the experimental data have accurately mapped deformations and stress states during testing. Further research is being conducted to investigate the influence of the size, shape, and placement of the hydrates. 30 refs., 15 figs.

  8. 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.

  9. A silicon doped hafnium oxide ferroelectric p–n–p–n SOI tunneling field–effect transistor with steep subthreshold slope and high switching state current ratio

    Directory of Open Access Journals (Sweden)

    Saeid Marjani

    2016-09-01

    Full Text Available In this paper, a silicon–on–insulator (SOI p–n–p–n tunneling field–effect transistor (TFET with a silicon doped hafnium oxide (Si:HfO2 ferroelectric gate stack is proposed and investigated via 2D device simulation with a calibrated nonlocal band–to–band tunneling model. Utilization of Si:HfO2 instead of conventional perovskite ferroelectrics such as lead zirconium titanate (PbZrTiO3 and strontium bismuth tantalate (SrBi2Ta2O9 provides compatibility to the CMOS process as well as improved device scalability. By using Si:HfO2 ferroelectric gate stack, the applied gate voltage is effectively amplified that causes increased electric field at the tunneling junction and reduced tunneling barrier width. Compared with the conventional p–n–p–n SOI TFET, the on–state current and switching state current ratio are appreciably increased; and the average subthreshold slope (SS is effectively reduced. The simulation results of Si:HfO2 ferroelectric p–n–p–n SOI TFET show significant improvement in transconductance (∼9.8X enhancement at high overdrive voltage and average subthreshold slope (∼35% enhancement over nine decades of drain current at room temperature, indicating that this device is a promising candidate to strengthen the performance of p–n–p–n and conventional TFET for a switching performance.

  10. Hazard assessment of vegetated slopes

    NARCIS (Netherlands)

    J.E. Norris; J.R. Greenwood; A. Achim; B.A. Gardiner; B.C. Nicoll; E. Cammeraat; S.B. Mickovski

    2008-01-01

    The hazard assessment of vegetated slopes are reviewed and discussed in terms of the stability of the slope both with and without vegetation, soil erosion and the stability of the vegetated slope from windthrow and snow loading. Slope stability can be determined by using either limit equilibrium or

  11. Separate effects tests to determine the thermal dispersion in structured pebble beds in the PBMR HPTU test facility

    Energy Technology Data Exchange (ETDEWEB)

    Toit, C.G. du, E-mail: jat.dutoit@nwu.ac.za; Rousseau, P.G.; Kgame, T.L.

    2014-05-01

    Thermal-fluid simulations are used extensively to predict the maximum fuel temperatures, flows, pressure drops and thermal capacitance of pebble bed gas cooled reactors in support of the reactor safety case. The PBMR company developed the HTTF test facility in cooperation with M-Tech Industrial (Pty) Ltd. and the North-West University in South Africa to conduct comprehensive separate effects tests as well as integrated effects tests to study the different thermal-fluid phenomena. This paper describes the separate effects tests that were conducted to determine the effect of the porous structure on the fluid effective thermal conductivity due to the thermal dispersion. It also presents the methodology applied in the data analysis to derive the resultant values of the effective thermal conductivity and its associated uncertainty.

  12. Effect of particle size and interparticle force on the fluidization behavior of gas-fluidized beds.

    Science.gov (United States)

    Valverde, J M; Castellanos, A; Mills, P; Quintanilla, M A S

    2003-05-01

    Gas-fluidized powders of fine particles display a fluidlike regime in which the bed does not have a yield strength, it expands uniformly as the gas velocity is increased and macroscopic bubbles are absent. In this paper we test the extension of this fluidlike regime as a function of particle size and interparticle attractive force. Our results show that for sufficiently large particles, bubbling initiates just after the solidlike fluidized regime as it is obtained experimentally by other workers. A scaling behavior of the solid-phase pressure in the fluidlike regime and a predictive criterion for the onset of macroscopic bubbling are analyzed in the light of these results.

  13. A graphical user interface (GUI) toolkit for the calculation of three-dimensional (3D) multi-phase biological effective dose (BED) distributions including statistical analyses.

    Science.gov (United States)

    Kauweloa, Kevin I; Gutierrez, Alonso N; Stathakis, Sotirios; Papanikolaou, Niko; Mavroidis, Panayiotis

    2016-07-01

    A toolkit has been developed for calculating the 3-dimensional biological effective dose (BED) distributions in multi-phase, external beam radiotherapy treatments such as those applied in liver stereotactic body radiation therapy (SBRT) and in multi-prescription treatments. This toolkit also provides a wide range of statistical results related to dose and BED distributions. MATLAB 2010a, version 7.10 was used to create this GUI toolkit. The input data consist of the dose distribution matrices, organ contour coordinates, and treatment planning parameters from the treatment planning system (TPS). The toolkit has the capability of calculating the multi-phase BED distributions using different formulas (denoted as true and approximate). Following the calculations of the BED distributions, the dose and BED distributions can be viewed in different projections (e.g. coronal, sagittal and transverse). The different elements of this toolkit are presented and the important steps for the execution of its calculations are illustrated. The toolkit is applied on brain, head & neck and prostate cancer patients, who received primary and boost phases in order to demonstrate its capability in calculating BED distributions, as well as measuring the inaccuracy and imprecision of the approximate BED distributions. Finally, the clinical situations in which the use of the present toolkit would have a significant clinical impact are indicated.

  14. Slope constrained Topology Optimization

    DEFF Research Database (Denmark)

    Petersson, J.; Sigmund, Ole

    1998-01-01

    pointwise bounds on the density slopes. A finite element discretization procedure is described, and a proof of convergence of finite element solutions to exact solutions is given, as well as numerical examples obtained by a continuation/SLP (sequential linear programming) method. The convergence proof...

  15. Tree- and Stand-Level Thinning Effects on Growth of European Beech (Fagus sylvatica L. on a Northeast- and a Southwest-Facing Slope in Southwest Germany

    Directory of Open Access Journals (Sweden)

    Daniela Diaconu

    2015-09-01

    Full Text Available Anticipated changes in climate and research findings on the drought sensitivity of beech have triggered controversial discussions about the future of European beech. We investigated the growth response of beech on the tree- and stand-level in mature stands to three different thinning intensities (no thinning, strong thinning, very strong thinning on a northeast- and southwest-facing slope in Southwest Germany. Linear mixed-effects models were formulated to describe effects on growth parameters on the tree- and stand-level (diameter, height, basal area, volume. At the stand-level, the stand basal area increment and stand volume increment were lower on the thinned plots. At the tree-level, the basal area increment significantly increased with increasing thinning intensity. The growth of individual trees was also influenced by initial tree size, the size-related rank of the tree within a stand, and by the aspect of the site. Our data indicate that growth of European beech is impaired on the southwest-facing slope with a warmer and drier climate and that a very strong thinning regime applied at advanced age can accelerate growth of European beech trees even on the warmer and drier site. Our findings, therefore, imply that in a warmer climate intensive thinning may also represent an important adaptive forest management measure in European beech stands.

  16. The origin of high hydraulic resistance for filter cakes of deformable particles: cell-bed deformation or surface-layer effect?

    OpenAIRE

    Meireles, Martine; Molle, Catherine; Clifton, Michael J.; Aimar, Pierre

    2004-01-01

    International audience; This study reports a numerical approach for modeling the hydraulic resistance of a filter cake of deformable cells. First, a mechanical and osmotic model that describes the volume fraction of solids in a bed of yeast cells as a function of the compressive pressure it experiences is presented. The effects of pressure on the compressibility of yeast cells beds were further investigated both by filtration experiments and by centrifugal experiments based on the multiple sp...

  17. Effects of NH3 on N2O Formation and Destruction in Fluidized Bed Coal Combustion

    Institute of Scientific and Technical Information of China (English)

    JianWeiYuan; BoFeng; 等

    1994-01-01

    The NH3 oxidation and reduction process are experimentally and kinetically studied in this paper,It is found that NH3 has contributions not only to N2O formation,but also to N2O destruction in certain conditions.The main product of homogeneous NH3 oxidation is found to be NO rather than N2O,but some bed materials and suplhur sorbents have catalytic contributions to N2O formation from NH3 oxidation.In reduction atmosphere,NH3 can promote the KC destruction.It is deduced that the ammonia injection into fluidized bed coal combustion flue gas can decrease both NOx and N2O emissions.The ammonia injection process is kinetically simulated in this study,and the reduction.rates of NOx and N2O are found to depend on temperature,O2 concentration,initial NOx and N2O concentrations,and amount of injected ammonia.

  18. 坡度对降雨溅蚀影响的研究%EFFECTS OF SLOPE GRADIENT ON RAINDROP SPLASH EROSION

    Institute of Scientific and Technical Information of China (English)

    刘和平; 符素华; 王秀颖; 徐丽; 方岚; 刘宝元; 路炳军

    2011-01-01

    利用可以分别收集不同方向溅蚀土样的土槽装置,选取9个坡度(5°~45°),采用北京的普通褐土,借助人工模拟降雨手段研究了降雨溅蚀的发生过程及溅蚀量与坡度的关系.结果表明,随着坡度的不同,各方向的溅蚀过程呈现三种形式:(1)产流前溅蚀率较小,产流后迅速达到峰值,之后逐渐减小并逐渐达到稳定,峰值与稳定溅蚀率相差2倍以上;(2)产流前溅蚀率最大,产流后迅速减小并趋于稳定;(3)整个降雨过程中没有明显起伏.各个坡度下,次降雨溅蚀量均为上坡最小,下坡最大.上坡和侧坡溅蚀量与坡度成负相关,可分别用直线和指数函数拟合.下坡溅蚀量、溅蚀总分散量和溅蚀净搬运量均随着坡度的增大而先增大后减小,且为线性关系,临界坡度为35°.本研究将有助于深入理解降雨溅蚀侵蚀机理,并可为布设水土保持措施提供理论依据.%Slope gradient is an important factor affecting raindrop splash erosion. Hence its effect was investigated using soil trays simulating nine slope gradients (9% , 18% , 27% , 36% , 47% , 58% , 70% , 84% , and 100% ) , and each soil tray was 0. 5 m × 0.5 m × 0. 1 m ( horizontal length × width × depth) in dimension, containing loamy soil,collected from Yanqing, Beijing. All the treatments were subjected to a simulated rainfall with a constant intensity of 67 mm h -1 for 1 hour. Specially designed samplers were used to partition total splash into directional components ( e. g.upslope, downslope, and lateral). Results indicate that splash erosion occurred in the following three patterns: ( 1 ) the rate was low prior to the generation of runoff, peaked rapidly at the beginning of runoff, decreased gradually and leveled off; (2) the rate was high prior to the generation of runoff and dropped rapidly after runoff was generated and then leveled off at a certain rate; or (3) the rate did not show any obvious fluctuation

  19. Mechanical interaction between roots and soil mass in slope vegetation

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The most basic function of slope vegetation is to strengthen rock and soil mass through plant roots which increase the shear strength of the slope markedly and thereby increase the stability of the slope. However, the calculation of the reinforcement ability of slope vegetation still remains at the stage of judging by experience, because it is rather difficult due to the intricacy and volatility of the force condition of plant roots in rock and soil medium. Although some scholars have tried to study the interaction between plant roots and soil mass, the systemic analysis of the mechanical reinforcement mechanism and the contribution of plant roots to strengthening the rock and soil mass on the surface of the slope is untapped. In this paper, by analyzing the mechanism of slope vegetation and the corresponding reinforcement effect, the effects that slope vegetation generates on the shear strength of slope soil mass are studied, thereby a theoretical basis for plant protection designing is provided.

  20. in Spouted Bed

    Directory of Open Access Journals (Sweden)

    Bronislaw Buczek

    2013-01-01

    Full Text Available Samples of active coke, fresh and spent after cleaning flue gases from communal waste incinerators, were investigated. The outer layers of both coke particles were separately removed by comminution in a spouted bed. The samples of both active cokes were analysed by means of densities, mercury porosimetry, and adsorption technique. Remaining cores were examined to determine the degree of consumption of coke by the sorption of hazardous emissions (SO2, HCl, and heavy metals through its bed. Differences in contamination levels within the porous structure of the particles were estimated. The study demonstrated the effectiveness of commercial active coke in the cleaning of flue gases.

  1. A geochemical investigation into the effect of coal rank on the potential environmental effects of CO2 sequestration in deep coal beds

    Science.gov (United States)

    Kolak, Jonathan J.; Burruss, Robert A.

    2005-01-01

    Coal samples of different rank were extracted in the laboratory with supercritical CO2 to evaluate the potential for mobilizing hydrocarbons during CO2 sequestration or enhanced coal bed methane recovery from deep coal beds. The concentrations of aliphatic hydrocarbons mobilized from the subbituminous C, high-volatile C bituminous, and anthracite coal samples were 41.2, 43.1, and 3.11 ?g g-1 dry coal, respectively. Substantial, but lower, concentrations of polycyclic aromatic hydrocarbons (PAHs) were mobilized from these samples: 2.19, 10.1, and 1.44 ?g g-1 dry coal, respectively. The hydrocarbon distributions within the aliphatic and aromatic fractions obtained from each coal sample also varied with coal rank and reflected changes to the coal matrix associated with increasing degree of coalification. Bitumen present within the coal matrix may affect hydrocarbon partitioning between coal and supercritical CO2. The coal samples continued to yield hydrocarbons during consecutive extractions with supercritical CO2. The amount of hydrocarbons mobilized declined with each successive extraction, and the relative proportion of higher molecular weight hydrocarbons increased during successive extractions. These results demonstrate that the potential for mobilizing hydrocarbons from coal beds, and the effect of coal rank on this process, are important to consider when evaluating coal beds for CO2 storage.

  2. Effects of space flight and -6 degrees bed rest on the neuroendocrine response to metabolic stress in physically fit subjects.

    Science.gov (United States)

    Ksinantová, Lucia; Koska, Juraj; Martinkovic, Miroslav; Vigas, Milan; Macho, Ladislav; Kvetnansky, Richard

    2004-06-01

    The aim of this study was to evaluate the association of plasma epinephrine (EPI) and norepinephrine (NE) responses to insulin-induced hypoglycemia (ITT) 3 weeks before the space flight (SF), on the fifth day of SF, on days 2 and 16 after landing in the first Slovak astronaut, and before and on the fifth day of prolonged bed rest (BR) in 15 military aircraft pilots, aged 33.5 +/- 1.4 years, body mass index (BMI) 26.5 +/- 0.7 kg/m(2), maximal oxygen uptake (VO(2max)) 55.2 +/- 2.4 mL/kg/min, who volunteered for the study. ITT was induced by i.v. administrations of 0.1 IU/kg body weight insulin (Actrapid HM) in a bolus. Insulin administration led to a comparable hypoglycemia in preflight, actual flight conditions, and before and after bed rest. ITT led to a pronounced increase in EPI levels and moderate increase in NE in preflight studies. However, an evidently reduced plasma elevation of EPI was found after insulin administration during SF and during BR. Thus, during the real microgravity in SF and simulated microgravity in BR, ITT activates the adrenomedullary system to less extent that at conditions of the Earth's gravitation. Post-flight changes in EPI and NE did not differ from those of preflight values, since SF was relatively short (8 days) and the readaptation to Earth's gravitation was fast. It seems that an increased blood flow in brain might be responsible for the reduced EPI response to insulin. Responses to ITT in physically fit subjects indicate the stimulus specificity of the deconditioning effect of 5 days of bed rest on the stress response.

  3. Effect of high sodium intake during 14 days of bed-rest on acid-base balance

    Science.gov (United States)

    Frings, P.; Baecker, N.; Heer, M.

    Lowering mechanical load like in microgravity is the dominant stimulus leading to bone loss However high dietary sodium intake is also considered as a risk factor for osteoporosis and thereby might exacerbate the microgravity induced bone loss In a metabolic balance non bed-rest study we have recently shown that a very high sodium intake leads to an increased bone resorption most likely because of a mild metabolic acidosis Frings et al FASEB J 19 5 A1345 2005 To test if mild metabolic acidosis also occurs during immobilization we examined the effect of increased dietary sodium on bone metabolism and acid-base balance in eight healthy male test subjects mean age 26 25 pm 3 49 years body weight 77 98 pm 4 34 kg in our metabolic ward during a 14-day head-down tilt HDT bed-rest study The study was designed as a randomized crossover study with two study periods Each period was divided into three parts 4 ambulatory days with 200 mmol sodium intake 14 days of bed-rest with either 550 mmol or 50 mmol sodium intake and 3 recovery days with 200 mmol sodium intake The sodium intake was altered by variations in dietary sodium chloride content Blood pH P CO2 and P O2 were analyzed in fasting morning fingertip blood samples several times during the entire study Bicarbonate HCO 3 - and base excess BE were calculated according to the Henderson-Hasselbach equation Preliminary results in the acid-base balance from the first study period 4 subjects with 550 mmol and 4 subjects with 50 mmol sodium intake strongly

  4. The effect of bubble plume on oxygen transfer for moving bed biofilm reactor

    Institute of Scientific and Technical Information of China (English)

    CHENG Wen; LIU Hu; WANG Meng; WANG Min

    2014-01-01

    The movement of the bubble plume plays an important role in the operation of a moving bed biofilm reactor (MBBR), and it directly affects the contact and the mixture of the gas-liquid-solid phases in the aeration tank and also the oxygen transfer from the gas phase to the liquid phase. In this study, the velocity field is determined by a 4-frame PTV as well as the time-averaged and time- dependent velocity distributions. The velocity distribution of the bubble plume is analyzed to evaluate the operating efficiency of the MBBR. The results show that the aeration rate is one of the main factors that sway the velocity distribution of the bubble plumes and affect the operating efficiency of the reactor.

  5. Effects of across-and along-slope ploughs on soil aggregate stability%横坡和顺坡耕作对紫色土土壤团聚体稳定性的影响

    Institute of Scientific and Technical Information of China (English)

    张怡; 何丙辉; 王仁新; 郭志敏; 唐柄哲

    2013-01-01

    Soil aggregate is an key soil fertility identification index which determines the quality and erosion resistance of soils. Soil organic carbon content somehow influences soil stability and soil water-stable aggregate forms. It is a critical driving factor of soil fertility and soil cushioning property. Farming measures also influence changes in soil organic carbon pool and different farming measures have different effects on soil physical and chemical property. To find proper tillage measures on slope croplands in purple soils, the effects of across- and along-slope ploughs on soil aggregate stability in purple soils were studied. Through plot runoff experiments, the characteristics of water-stable aggregates and organic carbon contents in top soils (0~20 cm) were studied, On the slope-land of South China, peasants preferred doing along-slope plough than across-slope plough because ease of along-slope plough. However, rill erosion easily occurred in along-slope plough conditions, especially in big rainfall events. This worsened the degree of soil erosion in the region. On the other hand, research on soil nutrient loss in across-slope plough conditions has sown that due to high risks and inputs, across-slope plough farming was unacceptable to most peasants. Studies have shown that soil aggregate organic carbon content accounts for 90% of surface soil nutrients and agricultural production activities occurred mostly in surface soils. This research studied the effects of across- and along-slope ploughs on water-stable aggregates and organic carbon in surface purple soils. The study offered some theoretical bases for effective utilization of soil management measures in slope-land conditions. Results showed that compared with along-slope plough, across-slope plough increased aggregate water stability index by 38.99%. Aggregate dispersion index in along-slope plough was 1.64 times that in across-slope plough. This suggested that erosion resistance in across-slope plough

  6. Slope earthquake stability

    CERN Document Server

    Changwei, Yang; Jing, Lian; Wenying, Yu; Jianjing, Zhang

    2017-01-01

    This book begins with the dynamic characteristics of the covering layerbedrock type slope, containing monitoring data of the seismic array, shaking table tests, numerical analysis and theoretical derivation. Then it focuses on the landslide mechanism and assessment method. It also proposes a model that assessing the hazard area based on the field investigations. Many questions, exercises and solutions are given. Researchers and engineers in the field of Geotechnical Engineering and Anti-seismic Engineering can benefit from it.

  7. Application of the Time-Dependent Mild-Slope Equations for the Simulation of Wake Effects in the Lee of a Farm of Wave Dragon Wave Energy Converters

    DEFF Research Database (Denmark)

    Beels, Charlotte; Troch, Peter; Visch, Kenneth De;

    2010-01-01

    in a time-dependent mild-slope equation model by using numerical sponge layers. In this paper the developed WEC implementation is applied to a single Wave Dragon WEC and multiple Wave Dragon WECs. The Wave Dragon WEC is a floating offshore converter of the overtopping type. Two wave reflectors focus...... and reservoir) are simulated as porous structures, exhibiting the same reflection, respectively absorption characteristics as obtained for the prototype Wave Dragon WEC. The wake effects behind a single Wave Dragon WEC are studied in detail for uni- and multidirectional waves. The shadow zone indicating...... the wake effect is decreasing with increasing directional spreading. The wake in the lee of a farm of five Wave Dragon WECs, installed in a staggered grid (3 WECs in the first row and 2 WECs in the second row), is calculated for three in-between distances of respectively D, 2D and 3D, with D the distance...

  8. ElevationSlope_SLOPE3p2M

    Data.gov (United States)

    Vermont Center for Geographic Information — This metadata applies to the following collection area(s): ( and related SLOPE datasets. Created using ArcGIS "SLOPE" command to produce change in elevation over the...

  9. ElevationSlope_SLOPE0p7M2013

    Data.gov (United States)

    Vermont Center for Geographic Information — This metadata applies to the following collection area(s): Rutland/GI Counties 2013 0.7m and related SLOPE datasets. Created using ArcGIS "SLOPE" command to produce...

  10. ElevationSlope_SLOPE0p7M2015

    Data.gov (United States)

    Vermont Center for Geographic Information — This metadata applies to the following collection area(s): Windham County 2015 0.7m and related SLOPE datasets. Created using ArcGIS "SLOPE" command to produce...

  11. ElevationSlope_SLOPE1p6M2010

    Data.gov (United States)

    Vermont Center for Geographic Information — This metadata applies to the following collection area(s): Missisquoi Upper 2010 1.6m and related SLOPE datasets. Created using ArcGIS "SLOPE" command to produce...

  12. ElevationSlope_SLOPE1p6M2012

    Data.gov (United States)

    Vermont Center for Geographic Information — This metadata applies to the following collection area(s): Addison County 2012 1.6m and related SLOPE datasets. Created using ArcGIS "SLOPE" command to produce...

  13. ElevationSlope_SLOPE0p7M2014

    Data.gov (United States)

    Vermont Center for Geographic Information — This metadata applies to the following collection area(s): Eastern VT 2014 0.7m and related SLOPE datasets. Created using ArcGIS "SLOPE" command to produce change in...

  14. ElevationSlope_SLOPE1p6M2008

    Data.gov (United States)

    Vermont Center for Geographic Information — This metadata applies to the following collection area(s): Missisquoi Lower 2008 1.6m and related SLOPE datasets. Created using ArcGIS "SLOPE" command to produce...

  15. ElevationSlope_SLOPE3p2M2004

    Data.gov (United States)

    Vermont Center for Geographic Information — This metadata applies to the following collection area(s): ( and related SLOPE datasets. Created using ArcGIS "SLOPE" command to produce change in elevation over the...

  16. Drainage effects on the transient, near-surface hydrologic response of a steep hillslope to rainfall: implications for slope stability, Edmonds, Washington, USA

    Science.gov (United States)

    Biavati, G.; Godt, J. W.; McKenna, J. P.

    2006-05-01

    Shallow landslides on steep (>25°) hillsides along Puget Sound have resulted in occasional loss of life and costly damage to property during intense or prolonged rainfall. As part of a larger project to assess landslide hazards in the Seattle area, the U.S. Geological Survey instrumented two coastal bluff sites in 2001 to observe the subsurface hydrologic response to rainfall. The instrumentation at one of these sites, near Edmonds, Washington, consists of two rain gauges, two water-content probes that measure volumetric water content at eight depths between 0.2 and 2.0 m, and two tensiometer nests that measure soil-water suction at six depths ranging from 0.2 to 1.5 m. Measurements from these instruments are used to test one- and two-dimensional numerical models of infiltration and groundwater flow. Capillary-rise tests, performed in the laboratory on soil sample from the Edmonds site, are used to define the soil hydraulic properties for the wetting process. The field observations of water content and suction show an apparent effect of porosity variation with depth on the hydraulic response to rainfall. Using a range of physical properties consistent with our laboratory and field measurements, we perform sensitivity analyses to investigate the effects of variation in physical and hydraulic properties of the soil on rainfall infiltration, pore-pressure response, and, hence, slope stability. For a two-layer-system in which the hydraulic conductivity of the upper layer is at least 10 times greater than the conductivity of the lower layer, and the infiltration rate is greater than the conductivity of the lower layer, a perched water table forms above the layer boundary potentially destabilizing the upper layer of soil. Two-dimensional modeling results indicate that the addition of a simple trench drain to the same two-layer slope has differing effects on the hydraulic response depending on the initial pressure head conditions. For slope-parallel flow conditions

  17. Drainage effects on the transient, near-surface hydrologic response of a steep hillslope to rainfall: Implications for slope stability, Edmonds, Washington, USA

    Science.gov (United States)

    Biavati, G.; Godt, J.W.; McKenna, J.P.

    2006-01-01

    Shallow landslides on steep (>25??) hillsides along Puget Sound have resulted in occasional loss of life and costly damage to property during intense or prolonged rainfall. As part of a larger project to assess landslide hazards in the Seattle area, the U.S. Geological Survey instrumented two coastal bluff sites in 2001 to observe the subsurface hydrologic response to rainfall. The instrumentation at one of these sites, near Edmonds, Washington, consists of two rain gauges, two water-content probes that measure volumetric water content at eight depths between 0.2 and 2.0 m, and two tensiometer nests that measure soil-water suction at six depths ranging from 0.2 to 1.5m. Measurements from these instruments are used to test one- and two-dimensional numerical models of infiltration and groundwater flow. Capillary-rise tests, performed in the laboratory on soil sample from the Edmonds site, are used to define the soil hydraulic properties for the wetting process. The field observations of water content and suction show an apparent effect of porosity variation with depth on the hydraulic response to rainfall. Using a range of physical properties consistent with our laboratory and field measurements, we perform sensitivity analyses to investigate the effects of variation in physical and hydraulic properties of the soil on rainfall infiltration, pore-pressure response, and, hence, slope stability. For a two-layer-system in which the hydraulic conductivity of the upper layer is at least 10 times greater than the conductivity of the lower layer, and the infiltration rate is greater than the conductivity of the lower layer, a perched water table forms above the layer boundary potentially destabilizing the upper layer of soil. Two-dimensional modeling results indicate that the addition of a simple trench drain to the same two-layer slope has differing effects on the hydraulic response depending on the initial pressure head conditions. For slope-parallel flow conditions

  18. Drainage effects on the transient, near-surface hydrologic response of a steep hillslope to rainfall: implications for slope stability, Edmonds, Washington, USA

    Directory of Open Access Journals (Sweden)

    G. Biavati

    2006-01-01

    Full Text Available Shallow landslides on steep (>25° hillsides along Puget Sound have resulted in occasional loss of life and costly damage to property during intense or prolonged rainfall. As part of a larger project to assess landslide hazards in the Seattle area, the U.S. Geological Survey instrumented two coastal bluff sites in 2001 to observe the subsurface hydrologic response to rainfall. The instrumentation at one of these sites, near Edmonds, Washington, consists of two rain gauges, two water-content probes that measure volumetric water content at eight depths between 0.2 and 2.0 m, and two tensiometer nests that measure soil-water suction at six depths ranging from 0.2 to 1.5 m. Measurements from these instruments are used to test one- and two-dimensional numerical models of infiltration and groundwater flow. Capillary-rise tests, performed in the laboratory on soil sample from the Edmonds site, are used to define the soil hydraulic properties for the wetting process. The field observations of water content and suction show an apparent effect of porosity variation with depth on the hydraulic response to rainfall. Using a range of physical properties consistent with our laboratory and field measurements, we perform sensitivity analyses to investigate the effects of variation in physical and hydraulic properties of the soil on rainfall infiltration, pore-pressure response, and, hence, slope stability. For a two-layer-system in which the hydraulic conductivity of the upper layer is at least 10 times greater than the conductivity of the lower layer, and the infiltration rate is greater than the conductivity of the lower layer, a perched water table forms above the layer boundary potentially destabilizing the upper layer of soil. Two-dimensional modeling results indicate that the addition of a simple trench drain to the same two-layer slope has differing effects on the hydraulic response depending on the initial pressure head conditions. For slope

  19. The effect of rowing ergometry and resistive exercise on skeletal muscle structure and function during bed rest.

    Science.gov (United States)

    Krainski, Felix; Hastings, Jeffrey L; Heinicke, Katja; Romain, Nadine; Pacini, Eric L; Snell, Peter G; Wyrick, Phil; Palmer, M Dean; Haller, Ronald G; Levine, Benjamin D

    2014-06-15

    Exposure to microgravity causes functional and structural impairment of skeletal muscle. Current exercise regimens are time-consuming and insufficiently effective; an integrated countermeasure is needed that addresses musculoskeletal along with cardiovascular health. High-intensity, short-duration rowing ergometry and supplemental resistive strength exercise may achieve these goals. Twenty-seven healthy volunteers completed 5 wk of head-down-tilt bed rest (HDBR): 18 were randomized to exercise, 9 remained sedentary. Exercise consisted of rowing ergometry 6 days/wk, including interval training, and supplemental strength training 2 days/wk. Measurements before and after HDBR and following reambulation included assessment of strength, skeletal muscle volume (MRI), and muscle metabolism (magnetic resonance spectroscopy); quadriceps muscle biopsies were obtained to assess muscle fiber types, capillarization, and oxidative capacity. Sedentary bed rest (BR) led to decreased muscle volume (quadriceps: -9 ± 4%, P antigravity muscles. Due to its integrated cardiovascular benefits, rowing ergometry could be a primary component of exercise prescriptions for astronauts or patients suffering from severe deconditioning.

  20. The effect of channel shape, bed morphology, and shipwrecks on flow velocities in the Upper St. Clair River

    Science.gov (United States)

    Czuba, Jonathan A.; Oberg, Kevin; Best, Jim; Parsons, Daniel R.

    2009-01-01

    In the Great Lakes of North America, the St. Clair River is the major outlet of Lake Huron and conveys water to Lake St. Clair which then flows to Lake Erie. One major topic of interest is morphological change in the St. Clair River and its impact on water levels in the Upper Great Lakes and connecting channel flows. A combined multibeam echosounder (MBES) bathymetric survey and acoustic Doppler current profiler (ADCP) flow survey of the outlet of Lake Huron and the Upper St. Clair River was conducted July 21 – 25, 2008. This paper presents how channel morphology and shipwrecks affect the flow in the Upper St. Clair River. The river is most constricted at the Blue Water Bridge near Port Huron, Michigan, with water velocities over 2 ms-1 for a flow of 5,200 m3s-1. Downstream of this constriction, the river flows around a bend and expands creating a large recirculation zone along the left bank due to flow separation. This recirculation zone reduces the effective channel width, and thus increases flow velocities to over 2 ms-1 in this region. The surveys reveal several shipwrecks on the bed of the St. Clair River, which possess distinct wakes in their flow velocity downstream of the wrecks. The constriction and expansion of the channel, combined with forcing of the flow by bed topography, initiates channel-scale secondary flow, creating streamwise vortices that maintain coherence downstream over a distance of several channel widths.

  1. Comparison of the effect of grounding the column wall in gas-solid fluidized beds on electrostatic charge generation

    Energy Technology Data Exchange (ETDEWEB)

    Sowinski, Andrew; Mayne, Antonio; Javed, Bassam; Mehrani, Poupak, E-mail: poupak.mehrani@uottawa.ca [University of Ottawa, Chemical and Biological Engineering Department, 161 Louis Pasteur St., Ottawa, Ontario, K1N 6N5 (Canada)

    2011-06-23

    In gas-solid fluidized beds as particles are fluidized, they continuously come into contact with other particles, as well as the fluidization column wall. This generates electrostatic charges by means of triboelectrification and frictional charging, leading to particle agglomeration, reactor wall fouling, and eventually process downtime and large financial losses. Grounding the fluidization column has been considered as a means of helping electrostatic charge dissipation within fluidized beds; however, in industrial applications despite the process vessels being grounded, the electrostatic problem still persists. This work focused on the effect of fluidization column grounding on particle wall fouling. Experiments were conducted in an atmospheric system consist of a 0.1 m in diameter carbon steel fluidization column. The mass and charge-to-mass ratio (q/m) of the particles that remained adhered to the column wall upon the completion of one hour fluidization period were measured in an electrically isolated and grounded columns to quantitatively determine the amount of reactor wall fouling. Polyethylene particles with different particle size ranges (300- 1000 {mu}m) were fluidized with extra dry air at 1.5 times their respective minimum fluidization velocity (u{sub mf}). Results obtained in the grounded fluidization column were not significantly different from those in the isolated column for all particle size ranges tested where the particles mass collected and q/m and were found to be generally similar.

  2. Numerical and experimental studies on effects of moisture content on combustion characteristics of simulated municipal solid wastes in a fixed bed

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Rui, E-mail: Sunsr@hit.edu.cn [School of Energy Science and Engineering, Harbin Institute of Technology, 92, West Dazhi Street, Harbin 150001 (China); Ismail, Tamer M., E-mail: temoil@aucegypt.edu [Department of Mechanical Engineering, Suez Canal University, Ismailia (Egypt); Ren, Xiaohan [School of Energy Science and Engineering, Harbin Institute of Technology, 92, West Dazhi Street, Harbin 150001 (China); Abd El-Salam, M. [Department of Basic Science, Cairo University, Giza (Egypt)

    2015-05-15

    Highlights: • The effects of moisture content on the burning process of MSW are investigated. • A two-dimensional mathematical model was built to simulate the combustion process. • Temperature distributions, process rates, gas species were measured and simulated. • The The conversion ratio of C/CO and N/NO in MSW are inverse to moisture content. - Abstract: In order to reveal the features of the combustion process in the porous bed of a waste incinerator, a two-dimensional unsteady state model and experimental study were employed to investigate the combustion process in a fixed bed of municipal solid waste (MSW) on the combustion process in a fixed bed reactor. Conservation equations of the waste bed were implemented to describe the incineration process. The gas phase turbulence was modeled using the k–ε turbulent model and the particle phase was modeled using the kinetic theory of granular flow. The rate of moisture evaporation, devolatilization rate, and char burnout was calculated according to the waste property characters. The simulation results were then compared with experimental data for different moisture content of MSW, which shows that the incineration process of waste in the fixed bed is reasonably simulated. The simulation results of solid temperature, gas species and process rate in the bed are accordant with experimental data. Due to the high moisture content of fuel, moisture evaporation consumes a vast amount of heat, and the evaporation takes up most of the combustion time (about 2/3 of the whole combustion process). The whole bed combustion process reduces greatly as MSW moisture content increases. The experimental and simulation results provide direction for design and optimization of the fixed bed of MSW.

  3. MONITORING OF COAL BED EXTRACTION AS AN EFFECTIVE TOOL FOR IMPROVING THE PRODUCTION RESULTS OF A MINE

    Directory of Open Access Journals (Sweden)

    Witold BIAŁY

    2015-07-01

    Full Text Available The basic source of information necessary for proper and effective management of a hard coal mine is continuous monitoring of the mining process. An increased number of machines and devices used in a mine caused a need for continuous monitoring of mining departments’ work. Monitoring of the extraction of hard coal beds is crucial for this process management, as it determines the proper course of the mining process. Hence, monitoring can be considered the most important element of the controlling process, especially in the area of mining process management in a mine. Effective monitoring and proper, quick reacting to any irregularities in this process have a significant influence on the production results of a mine.

  4. Decreasing ventromedial prefrontal cortex deactivation in risky decision making after simulated microgravity: Effects of -6 degree head-down tilt bed rest

    Directory of Open Access Journals (Sweden)

    Li-Lin eRao

    2014-05-01

    Full Text Available Space is characterized by risk and uncertainty. As humans play an important role in long-duration space missions, the ability to make risky decisions effectively is important for astronauts who spend extended time periods in space. The present study used the Balloon Analog Risk Task to conduct both behavioral and fMRI experiments to evaluate the effects of simulated microgravity on individuals’ risk-taking behavior and the neural basis of the effect. The results showed that participants’ risk-taking behavior was not affected by bed rest. However, we found that the ventromedial prefrontal cortex (VMPFC showed less deactivation after bed rest and that the VMPFC activation in the active choice condition showed no significant difference between the win outcome and the loss outcome after bed rest, although its activation was significantly greater in the win outcome than in the loss outcome before bed rest. These results suggested that the participants showed a decreased level of value calculation after the bed rest. Our findings can contribute to a better understanding of the effect of microgravity on individual higher-level cognitive functioning.

  5. The Effects of Three Sessions of Running on a Negative Slope on Serum Levels of Liver Enzymes in Adult Male Rats

    Directory of Open Access Journals (Sweden)

    Mohsen Rezaei

    2013-05-01

    Full Text Available Background: The purpose of this study was to investigate the effects of three sessions of running on a negative slope (eccentric contraction on changes of the serum levels of aspartate aminotransferase (AST and alanin aminotransferaze (ALT in adult male rats. Materials and Methods: 20 adult male rats were divided randomly into two equal groups (exercise and control. Levels of AST and ALT in both groups were measured in a fasting state, 24 hours before and 24 hours after the last session of training.Results: Exercise increased the levels of serum AST and ALT enzymes, significantly (p<0.05.Conclusion: Eccentric exercise, without allowing enough time for returning to the pre-exercise state, leads to the damage of some body organs such as the liver.

  6. Effect of downward seepage on turbulent flow characteristics and bed morphology around bridge piers

    Science.gov (United States)

    Chavan, Rutuja; Sharma, Anurag; Kumar, Bimlesh

    2017-03-01

    In this work, experimental investigations have been pursued to analyse the influence of downward seepage on the turbulent characteristics of flow and corresponding changes in vortex structure around circular bridge pier in alluvial channel. Experiments were conducted in sand bed channel with circular piers of different sizes for no seepage, 10% seepage and 20% seepage cases. The measurement of turbulent flow statistics such as velocity and Reynolds stresses is found to be negative within the scour hole at upstream of the pier whereas application of downward seepage retards the reversal of the flow causing a decrement in the velocity and Reynolds stresses. Higher Reynolds shear stress prevails at the downstream side because of the production of wake vortices. Contribution of all bursting events to the total Reynolds shear stress production has been observed to increase with downward seepage. The analysis of integral scale suggest that size of eddies increases with seepage, which is responsible for increase in particle mobility. Initially rate of scouring is more which abatements gradually with expanding time as well as with the increased of downward seepage. Presence of downward seepage reduces the depth and length of vortex and shifts towards downstream side of the pier.

  7. Effect of filling fraction on the performance of sponge-based moving bed biofilm reactor.

    Science.gov (United States)

    Zhang, Xinbo; Chen, Xun; Zhang, Chunqing; Wen, Haitao; Guo, Wenshan; Ngo, Huu Hao

    2016-11-01

    Cubic-shaped polyurethane sponges (15×15×15mm) in the form of biofilm carriers were used in a moving bed biofilm reactor (MBBR) for treating synthetic domestic wastewater. Results indicated there was no significant difference in total organic carbon (TOC) and ammonia (NH4(+)-N) removal at different filling fractions. Three reactors exhibited high removal efficiencies of over 93% TOC and 95% NH4(+)-N on average at an HRT of 12h and aeration flow of 0.09m(3)/h. However, total nitrogen (TN) removal and simultaneous nitrification and denitrification (SND) increased with increasing the filling fraction. TN removal averaged at 77.2, 85.5% and 86.7% in 10%, 20% and 30% filling fraction reactor, respectively. Correspondingly, SND were 85.5±8.7%, 91.3±9.4% and 93.3±10.2%. Moreover, it was observed that sponge carriers in the 20% filling fraction reactor achieved the maximum biomass amount per gram sponge, followed by the 10% and 30% filling fraction reactors.

  8. Application of the time-dependent mild-slope equations for the simulation of wake effects in the lee of a farm of Wave Dragon wave energy converters

    Energy Technology Data Exchange (ETDEWEB)

    Beels, Charlotte; Troch, Peter; De Visch, Kenneth; De Backer, Griet [Ghent University, Department of Civil Engineering, Technologiepark 904, B-9052 Zwijnaarde (Belgium); Kofoed, Jens Peter [Aalborg University, Department of Civil Engineering, Sohngaardsholmsvej 57, DK-9000 Aalborg (Denmark)

    2010-08-15

    Time-dependent mild-slope equations have been extensively used to compute wave transformations near coastal and offshore structures for more than 20 years. Recently the wave absorption characteristics of a Wave Energy Converter (abbreviated as WEC) of the overtopping type have been implemented in a time-dependent mild-slope equation model by using numerical sponge layers. In this paper the developed WEC implementation is applied to a single Wave Dragon WEC and multiple Wave Dragon WECs. The Wave Dragon WEC is a floating offshore converter of the overtopping type. Two wave reflectors focus the incident wave power towards a ramp. The focussed waves run up the ramp and overtop in a water reservoir above mean sea level. The obtained potential energy is converted into electricity when the stored water drains back to the sea through hydro turbines. The wave reflectors and the main body (ramp and reservoir) are simulated as porous structures, exhibiting the same reflection, respectively absorption characteristics as obtained for the prototype Wave Dragon WEC. The wake effects behind a single Wave Dragon WEC are studied in detail for uni- and multidirectional waves. The shadow zone indicating the wake effect is decreasing with increasing directional spreading. The wake in the lee of a farm of five Wave Dragon WECs, installed in a staggered grid (3 WECs in the first row and 2 WECs in the second row), is calculated for three in-between distances of respectively D, 2D and 3D, with D the distance between the tips of the wave reflectors of a single WEC. As a result, a farm of five Wave Dragon WECs installed in a staggered grid with an in-between distance of 2D is preferred, when taking cost and spatial considerations into account. (author)

  9. Comments on the slope function

    CERN Document Server

    Kim, Minkyoo

    2016-01-01

    The exact slope function was first proposed in $SL(2)$ sector and generalized to $SU(2)$ sector later. In this note, we consider the slope function in $SU(1|1)$ sector of ${\\cal N}=4$ SYM. We derive the quantity through the method invented by N. Gromov and discuss about its validity. Further, we give comments on the slope function in deformed SYM.

  10. Prediction of slope failure due to earthquake

    Institute of Scientific and Technical Information of China (English)

    CHEN XiaoLi; KATO Nobuaki; TSUNAKI Ryosuke; MUKAI Keiji

    2009-01-01

    The earthquake-triggered landslides and slope failures are common phenomena during strong earthquakes and have drawn more attention from the world because of severe hazards they induced.These hazards usually cannot be prevented by current mitigating measures,thus,it becomes more and more important to develop a precise technique for the risk assessment of earthquake-induced failures in the mountainous area.The application of discrimination analysis method is proved to be successful and effective in the prediction of earthquake-triggered landslides and slope failures in the region of Imokawa Basin in Japan.Diacriminant score can be used to assess the relative risk of slope failures,as the score increases,the possibility of slope failures occurrence increases accordingly.At the same time,the variables in the judgement formula,such as slope gradient,slope curvature and seismic peak ground acceleration,are easy to obtain.This advantage makes this method more practical and manipulable than others at present.In order to apply this method more effectively,there are still several problems to resolve.

  11. Limited effect of fly-wheel and spinal mobilization exercise countermeasures on lumbar spine deconditioning during 90 d bed-rest in the Toulouse LTBR study

    Science.gov (United States)

    Belavý, Daniel L.; Ohshima, Hiroshi; Bareille, Marie-Pierre; Rittweger, Jörn; Felsenberg, Dieter

    2011-09-01

    We examined the effect of high-load fly-wheel (targeting the lower-limb musculature and concurrent loading of the spine via shoulder restraints) and spinal movement countermeasures against lumbar spine muscle atrophy, disc and spinal morphology changes and trunk isokinetic torque loss during prolonged bed-rest. Twenty-four male subjects underwent 90 d head-down tilt bed-rest and performed either fly-wheel (FW) exercises every three days, spinal movement exercises in lying five times daily (SpMob), or no exercise (Ctrl). There was no significant impact of countermeasures on losses of isokinetic trunk flexion/extension ( p≥0.65). Muscle volume change by day-89 of bed-rest in the psoas, iliacus, lumbar erector spinae, lumbar multifidus and quadratus lumborum, as measured via magnetic resonance imaging (MRI), was statistically similar in all three groups ( p≥0.33). No significant effect on MRI-measures of lumbar intervertebral disc volume, spinal length and lordosis ( p≥0.09) were seen either, but there was some impact ( p≤0.048) on axial plane disc dimensions (greater reduction than in Ctrl) and disc height (greater increases than in Ctrl). MRI-data from subjects measured 13 and 90-days after bed-rest showed partial recovery of the spinal extensor musculature by day-13 after bed-rest with this process complete by day-90. Some changes in lumbar spine and disc morphology parameters were still persistent 90-days after bed-rest. The present results indicate that the countermeasures tested were not optimal to maintain integrity of the spine and trunk musculature during bed rest.

  12. Bed rest during pregnancy

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/patientinstructions/000581.htm Bed rest during pregnancy To use the sharing features on ... your daily activities. Why Do I Need Bed Rest? Bed rest used to be recommended routinely for ...

  13. Soil application of ash produced by low-temperature fluidized bed gasification: effects on soil nutrient dynamics and crop response

    DEFF Research Database (Denmark)

    Müller-Stöver, Dorette Sophie; Ahrenfeldt, Jesper; Holm, Jens Kai

    2012-01-01

    Recycling of residual products of bioenergy conversion processes is important for adding value to the technologies and as a potential beneficial soil fertility amendment. In this study, two different ash materials originating from low temperature circulating fluidized bed (LT-CFB) gasification...... of either wheat straw (SA) or residue fibers mainly from citrus peels (CP) were tested regarding their potential to be used as fertilizer on agricultural soils. A soil incubation study, a greenhouse experiment with barley and faba bean, and an accompanying outdoor experiment with maize were carried out...... to investigate the effects of the ashes on soil microbiological and chemical properties and on the response of the three crops. The ash treatments were compared with a control treatment that received only nitrogen, magnesium, and sulphur (CO) and a fully fertilized control (COPK). Soil microbial parameters were...

  14. No effect of artificial gravity on lung function with exercise training during head-down bed rest

    Science.gov (United States)

    Su, Longxiang; Guo, Yinghua; Wang, Yajuan; Wang, Delong; Liu, Changting

    2016-04-01

    The aim of this study is to explore the effectiveness of microgravity simulated by head-down bed rest (HDBR) and artificial gravity (AG) with exercise on lung function. Twenty-four volunteers were randomly divided into control and exercise countermeasure (CM) groups for 96 h of 6° HDBR. Comparisons of pulse rate, pulse oxygen saturation (SpO2) and lung function were made between these two groups at 0, 24, 48, 72, 96 h. Compared with the sitting position, inspiratory capacity and respiratory reserve volume were significantly higher than before HDBR (0° position) (P control nor CM groups showed significant differences in pulse rate, SpO2, pulmonary volume and pulmonary ventilation function over the HDBR observation time. Postural changes can lead to variation in lung volume and ventilation function, but a HDBR model induced no changes in pulmonary function and therefore should not be used to study AG countermeasures.

  15. Effect of hydrogen combustion reaction on the dehydrogenation of ethane in a fixed-bed catalytic membrane reactor

    Institute of Scientific and Technical Information of China (English)

    Masoud Hasany; Mohammad Malakootikhah; Vahid Rahmanian; Soheila Yaghmaei

    2015-01-01

    A two-dimensional non-isothermal mathematical model has been developed for the ethane dehydrogenation reaction in a fixed-bed catalytic membrane reactor. Since ethane dehydrogenation is an equilibrium reaction, removal of produced hydrogen by the membrane shifts the thermodynamic equilibrium to ethylene production. For further displacement of the dehydrogenation reaction, oxidative dehydrogenation method has been used. Since ethane dehydrogenation is an endothermic reaction, the energy produced by the oxidative dehydrogena-tion method is consumed by the dehydrogenation reaction. The results show that the oxidative dehydrogenation method generated a substantial improvement in the reactor performance in terms of high conversions and significant energy saving. It was also established that the sweep gas velocity in the shell side of the reactor is one of the most important factors in the effectiveness of the reactor.

  16. Effect of HCO3- concentration on anammox nitrogen removal rate in a moving bed biofilm reactor.

    Science.gov (United States)

    Zekker, Ivar; Rikmann, Ergo; Tenno, Toomas; Vabamäe, Priit; Kroon, Kristel; Loorits, Liis; Saluste, Alar; Tenno, Taavo

    2012-01-01

    Anammox biomass enriched in a moving bed biofilm reactor (MBBR) fed by actual sewage sludge reject water and synthetically added NO2- was used to study the total nitrogen (TN) removal rate of the anammox process depending on bicarbonate (HCO3-) concentration. MBBR performance resulted in the maximum TN removal rate of 1100 g N m(-3) d(-1) when the optimum HCO3- concentration (910 mg L(-1)) was used. The average reaction ratio of NO2- removal, NO3- production and NH4+ removal were 1.18/0.20/1. When the HCO3- concentration was increased to 1760mg L(-1) the TN removal rate diminished to 270 g N m(-3) d(-1). The process recovered from bicarbonate inhibition within 1 week. The batch tests performed with biomass taken from the MBBR showed that for the HCO3- concentration of 615 mg L(-1) the TN removal rate was 3.3 mg N L(-1) h(-1), whereas for both lower (120 mg L(-1)) and higher (5750 mg L(-1)) HCO3- concentrations the TN removal rates were 2.3 (+/- 0.15) and 1.6 (+/- 0.12) mg N L(-1) d(-1), respectively. PCR and DGGE analyses resulted in the detection of uncultured Planctomycetales bacterium clone P4 and, surprisingly, low-oxygen-tolerant aerobic ammonia oxidizers. The ability of anammox bacteria for mixotrophy was established by diminished amounts of nitrate produced when comparing the experiments with an organic carbon source and an inorganic carbon source.

  17. Effect of dietary sodium on fluid/electrolyte regulation during bed rest

    Science.gov (United States)

    Williams, W. Jon; Schneider, Suzanne M.; Gretebeck, Randall J.; Lane, Helen W.; Stuart, Charles A.; Whitson, Peggy A.

    2003-01-01

    BACKGROUND: A negative fluid balance during bed rest (BR) is accompanied by decreased plasma volume (PV) which contributes to cardiovascular deconditioning. HYPOTHESIS: We hypothesized that increasing dietary sodium while controlling fluid intake would increase plasma osmolality (POSM), stimulate fluid conserving hormones, and reduce fluid/electrolyte (F/E) losses during BR; conversely, decreasing dietary sodium would decrease POSM, suppress fluid conserving hormones, and increase F/E losses. METHODS: We controlled fluid intake (30 ml x kg(-1) x d(-1)) in 17 men who consumed either a 4.0 +/- 0.06 g x d(-1) (174 mmol x d(-1)) (CONT; n = 6), 1.0 +/- 0.02 g x d(-1) (43 mmol x d(-1)) (LS; n = 6), or 10.0 +/- 0.04 g x d(-1) (430 mmol x d(-1)) (HS; n = 5) sodium diet before, during, and after 21 d of 6 degrees head-down BR. PV, total body water, urine volume and osmolality, POSM, and F/E controlling hormone concentrations were measured. RESULTS: In HS subjects, plasma renin activity (-92%), plasma/urinary aldosterone (-59%; -64%), and PV (-15.0%; 6.0 ml x kg(-1); p plasma atrial natriuretic peptide (+34%) and urine antidiuretic hormone (+24%) increased during BR (p plasma renin activity (+166%), plasma aldosterone (+167%), plasma antidiuretic hormone (+19%), and urinary aldosterone (+335%) increased with no change in PV compared with CONT (p < 0.05). Total body water did not change in any of the subjects. CONCLUSIONS: Contrary to our hypothesis, increasing dietary sodium while controlling fluid intake during BR resulted in a greater loss of PV compared with the CONT subjects. Reducing dietary sodium while controlling fluid intake did not alter the PV response during BR compared with CONT subjects.

  18. Assessment of highway slope failure using neural networks

    Institute of Scientific and Technical Information of China (English)

    Tsung-lin LEE; Hung-ming LIN; Yuh-pin LU

    2009-01-01

    An artificial intelligence technique of back-propagation neural networks is used to assess the slope failure. On-site slope failure data from the South Cross-Island Highway in southern Taiwan are used to test the performance of the neural network model. The numerical results demonstrate the effectiveness of artificial neural networks in the evaluation of slope failure potential based on five major factors, such as the slope gradient angle, the slope height, the cumulative precipitation, daily rainfall and strength of materials.

  19. [Treatment effect of biological filtration and vegetable floating-bed combined system on greenhouse turtle breeding wastewater].

    Science.gov (United States)

    Chen, Chong-Jun; Zhang, Rui; Xiang, Kun; Wu, Wei-Xiang

    2014-08-01

    Unorganized discharge of greenhouse turtle breeding wastewater has brought several negative influences on the ecological environment in the rural area of Yangtze River Delta. Biological filtration and vegetable floating-bed combined system is a potential ecological method for greenhouse turtle breeding wastewater treatment. In order to explore the feasibility of this system and evaluate the contribution of vegetable uptake of nitrogen (N) and phosphorus (P) in treating greenhouse turtle breeding wastewater, three types of vegetables, including Ipomoea aquatica, lettuce and celery were selected in this study. Results showed the combined system had a high capacity in simultaneous removal of organic matter, N and P. The removal efficiencies of COD, NH4(+)-N, TN and TP from the wastewater reached up to 93.2%-95.6%, 97.2%-99.6%, 73.9%-93.1% and 74.9%-90.0%, respectively. System with I. aquatica had the highest efficiencies in N and P removal, followed by lettuce and celery. However, plant uptake was not the primary pathway for TN arid TP removal in the combined system. The vegetable uptake of N and P accounted for only 9.1%-25.0% of TN and TP removal from the wastewater while the effect of microorganisms would be dominant for N and P removal. In addition, the highest amounts of N and P uptake in I. aquatica were closely related with the biomass of plant. Results from the study indicated that the biological filtration and vegetable floating-bed combined system was an effective approach to treating greenhouse turtle breeding wastewater in China.

  20. Health impact and cost-effectiveness of a private sector bed net distribution: experimental evidence from Zambia

    Science.gov (United States)

    2013-01-01

    Background Relatively few programmes have attempted to actively engage the private sector in national malaria control efforts. This paper evaluates the health impact of a large-scale distribution of insecticide-treated nets (ITNs) conducted in partnership with a Zambian agribusiness, and its cost-effectiveness from the perspective of the National Malaria Control Programme (NMCP). Methods The study was designed as a cluster-randomized controlled trial. A list of 81,597 cotton farmers was obtained from Dunavant, a contract farming company in Zambia’s cotton sector, in December 2010. 39,963 (49%) were randomly selected to obtain one ITN each. Follow-up interviews were conducted with 438 farmers in the treatment and 458 farmers in the control group in June and July 2011. Treatment and control households were compared with respect to bed net ownership, bed net usage, self-reported fever, and self-reported confirmed malaria. Cost data was collected throughout the programme. Results The distribution effectively reached target beneficiaries, with approximately 95% of households in the treatment group reporting that they had received an ITN through the programme. The average increase in the fraction of household members sleeping under an ITN the night prior to the interview was 14.6 percentage points (p-value <0.001). Treatment was associated with a 42 percent reduction in the odds of self-reported fever (p-value <0.001) and with a 49 percent reduction in the odds of self-reported malaria (p-value 0.002). This was accomplished at a cost of approximately five US$ per ITN to Zambia’s NMCP. Conclusions The results illustrate that existing private sector networks can efficiently control malaria in remote rural regions. The intra-household allocation of ITNs distributed through this channel was comparable to that of ITNs received from other sources, and the health impact remained substantial. PMID:23506170

  1. Lacustrine Basin Slope Break — A New Domain of Strata and Lithological Trap Exploration

    Institute of Scientific and Technical Information of China (English)

    WangYingmin; LiuHao; XinRenchen; JinWudi; WangYuan; LiWeiguo

    2004-01-01

    Based on the studies of the Songliao Basin characterized by Cretaceous down-warping, of the Jurassic compressional flexural Junggar basin and of the Bohai Bay Basin characterized by Paleogene rifting, the multiple-grades slope break has developed in lacustrine basins of different origins. Their genetic types can be divided into tectonic slope break, depositional slope break and erodent slope break. The dominant agent of the slope break is tectogenesis, and the scale of slope breaks relates with the size of tectogenesis. The results of the study show that control of mutual grades slope breaks on atectonic traps mainly represent: 1) Atectonic traps develop close to mutual grades slope breaks, with beads-shaped distribution along the slope breaks. 2) In the longitudinal direction, the development of atectonic traps is characterized by the inheritance. 3) Different slope breaks and their different geographical positions can lead to different development types of atectonic traps. 4) A slope break can form different kinds of atectonic traps because of its great lateral variation. 5) The existence of mutual-grade slope breaks leads to different responses of erosion and deposition at different geographical positions in the basin. The oil source bed, reservoir and cap rock combination of atectonic traps is fine. 6) The oil-bearing condition of atectonic traps controlled by slope breaks is very favorable.

  2. Three-dimensional analysis of slopes reinforced with piles

    Institute of Scientific and Technical Information of China (English)

    高玉峰; 叶茂; 张飞

    2015-01-01

    Based on the upper bound of limit analysis, the plane-strain analysis of the slopes reinforced with a row of piles to the 3D case was extended. A 3D rotational failure mechanism was adopted to yield the upper bound of the factor of safety. Parametric studies were carried out to explore the end effects of the slope failures and the effects of the pile location and diameter on the safety of the reinforced slopes. The results demonstrate that the end effects nearly have no effects on the most suitable location of the installed piles but have significant influence on the safety of the slopes. For a slope constrained to a narrow width, the slope becomes more stable owing to the contribution of the end effects. When the slope is reinforced with a row of piles in small space between piles, the effects of group piles are significant for evaluating the safety of slopes. The presented method is more appropriate for assessing the stability of slopes reinforced with piles and can be also utilized in the design of plies stabilizing the unstable slopes.

  3. Effectiveness of soil and water conservation structures in reducing runoff and soil loss for different land use and slope gradients: Case study from northern Ethiopia

    Science.gov (United States)

    Taye, Gebeyehu; Poesen, Jean; Vanwesemael, Bas; Vanmaercke, Matthias; Teka, Daniel; Deckers, Jozef; Goosse, Tom; Maetens, Willem; Nyssen, Jan; Hallet, Vincent; Haregeweyn, Nigussie

    2014-05-01

    Land degradation and recurrent drought are the major threats to rain-fed agriculture in the semi-arid Ethiopian highlands. To mitigate drought and to ensure food security in the Tigray region, water harvesting using reservoirs for irrigation development has become a priority since 1990. However, the success of water harvesting in reservoirs is limited due to the reduced inflow. As a result, less area is irrigated than originally planned. The aim of this study is to investigate the effectiveness of soil and water conservation (SWC) structures in reducing runoff and soil loss under different land use types and slope gradients. Six runoff measuring sites, corresponding to three slope gradients (5%, 12% and 16%) were established for cropland and rangeland in the Mayleba catchment (Tigray). In total, 21 large runoff plots (with lengths of 60 to 100 m and widths of 10 m) were monitored daily for runoff production and soil loss during the main rainy season (July-September) in 2010. For each site in cropland, three plots were installed and treated with stone bunds and stone bunds with trenches in addition to a control plot. At each site in rangeland four runoff plots were installed: a plot treated with stone bunds, a plot treated with trenches, a plot treated with stone bunds and trenches as well as a control plot. Overall uncertainties on the runoff and soil loss measurements were estimated by means of Monte Carlo simulation techniques. The results show that the seasonal runoff coefficient (RCs) was much higher for rangeland (0.38 < RCs < 0.50) compared to RCs-values for cropland (0.11 < RCS < 0.15). Seasonal soil loss (SLs) values were five to six times larger on rangeland (28.6 < SLs < 50.0 ton ha-1) compared to that for cropland (4.6 < SLs < 11.4 ton ha-1). All tested SWC structures are effective in reducing runoff and soil loss compared to control plots. However, reduction in RCs were relatively much smaller than reductions in SLs. Trenches and stone bunds with

  4. 边坡侧面挖掘对建筑稳定性的影响——以重庆为例%Effect of Side Slope Excavation on Construction Stability-Taking Chongqing as an Example

    Institute of Scientific and Technical Information of China (English)

    黄治国

    2016-01-01

    Study in Chongqing mountain area construction side slope excavation of the effect on the stability of the building, to Chongqing slope safety design of the building to provide accurate basis. The current envelope with positive slope excavation construction earthquake-resistance design, does not take into account the effect of horizontal displacement difference, this will lead to the structure of the structure is not stable, safe hidden trouble. Put forward a kind of side slope mining in Chongqing mountain building based on the finite element method. According to the finite element analysis of stress on the construction side slope excavation model is set up, using the side slope excavation under the structure of the geometric equations, the structural equation and energy equation and the stiffness equation, the winning side slope excavation under the structure of the balance equation, the complete side slope excavation analysis of the stability of the building. The simulation experimental results show that the improved method can carry on the more precise to the slope stability of the building performance analysis, the effect is satisfactory.%研究重庆山区建筑中边坡侧面挖掘对建筑稳定性的影响,能够为重庆坡地建筑物的安全设计提供准确的依据.当前采用边坡正面挖掘进行建筑抗震性的包络设计,没有考虑横向位移差的作用,这样就会导致建筑物的结构不稳定,带来安全隐患.提出一种基于有限元的重庆山区建筑中边坡侧面挖掘的方法.根据有限元分析法建立边坡侧面挖掘下建筑的受力模型,利用边坡侧面挖掘下建筑物的几何方程、结构方程与势能方程求出单元刚度方程,最终获得边坡侧面挖掘下建筑物的平衡方程,完成边坡侧面挖掘对建筑稳定性的分析.仿真实验结果表明,改进方法能够对坡地建筑物的稳定性能进行更精确的分析,效果令人满意.

  5. Mycorrhizal aspects in slope stabilisation

    Science.gov (United States)

    Graf, Frank

    2016-04-01

    In order to re-colonise and stabilise slopes affected by superficial soil failure with plants essential requirements have to be met: the plants must grow the plants must survive sustainably plant succession must start and continuously develop These requirements, however, are anything but easy given, particularly under the often hostile environmental conditions dominating on bare and steep slopes. Mycorrhizal fungi, the symbiotic partners of almost all plants used in eco-engineering, are said to improve the plants' ability to overcome periods governed by strongly (growth) limiting factors. Subsequently, results of investigations are presented of mycorrhizal effects on different plant and soil functions related to eco-engineering in general and soil and slope stabilisation in particular. Generally, inoculation yielded higher biomass of the host plants above as well as below ground. Furthermore, the survival rate was higher for mycorrhized compared to non-mycorrhized plants, particularly under extreme environmental conditions. However, the scale of the mycorrhizal impact may be species specific of both the plant host as well as the fungal partner(s) and often becomes evident only after a certain time lag. Depending on the plant-fungus combination the root length per soil volume was found to be between 0 and 2.5 times higher for inoculated compared to non-inoculated specimens. On an alpine graded ski slope the survival of inoculated compared to non-treated Salix herbacea cuttings was significant after one vegetation period only for one of the three added mycorrhizal fungus species. However, after three years all of the inoculated plantlets performed significantly better than the non-inoculated controls. The analysis of the potential for producing and stabilising soil aggregates of five different ectomycorrhizal fungi showed high variation and, for the species Inocybe lacera, no significant difference compared to untreated soil. Furthermore, inoculation of Salix

  6. Atmospheric stability effects on wind fields and scalar mixing within and just above a subalpine forest in sloping terrain

    Science.gov (United States)

    Burns, Sean P.; Sun, Jielun; Lenschow, D.H.; Oncley, S.P.; Stephens, B.B.; Yi, C.; Anderson, D.E.; Hu, Jiawen; Monson, Russell K.

    2011-01-01

    Air temperature Ta, specific humidity q, CO2 mole fraction ??c, and three-dimensional winds were measured in mountainous terrain from five tall towers within a 1 km region encompassing a wide range of canopy densities. The measurements were sorted by a bulk Richardson number Rib. For stable conditions, we found vertical scalar differences developed over a "transition" region between 0.05 1), the vertical scalar differences reached a maximum and remained fairly constant with increasing stability. The relationships q and ??c have with Rib are explained by considering their sources and sinks. For winds, the strong momentum absorption in the upper canopy allows the canopy sublayer to be influenced by pressure gradient forces and terrain effects that lead to complex subcanopy flow patterns. At the dense-canopy sites, soil respiration coupled with wind-sheltering resulted in CO2 near the ground being 5-7 ??mol mol-1 larger than aloft, even with strong above-canopy winds (near-neutral conditions). We found Rib-binning to be a useful tool for evaluating vertical scalar mixing; however, additional information (e.g., pressure gradients, detailed vegetation/topography, etc.) is needed to fully explain the subcanopy wind patterns. Implications of our results for CO2 advection over heterogenous, complex terrain are discussed. ?? 2010 Springer Science+Business Media B.V.

  7. Nitrate removal, communities of denitrifiers and adverse effects in different carbon substrates for use in denitrification beds.

    Science.gov (United States)

    Warneke, Sören; Schipper, Louis A; Matiasek, Michael G; Scow, Kate M; Cameron, Stewart; Bruesewitz, Denise A; McDonald, Ian R

    2011-11-01

    Denitrification beds are containers filled with wood by-products that serve as a carbon and energy source to denitrifiers, which reduce nitrate (NO(3)(-)) from point source discharges into non-reactive dinitrogen (N(2)) gas. This study investigates a range of alternative carbon sources and determines rates, mechanisms and factors controlling NO(3)(-) removal, denitrifying bacterial community, and the adverse effects of these substrates. Experimental barrels (0.2 m(3)) filled with either maize cobs, wheat straw, green waste, sawdust, pine woodchips or eucalyptus woodchips were incubated at 16.8 °C or 27.1 °C (outlet temperature), and received NO(3)(-) enriched water (14.38 mg N L(-1) and 17.15 mg N L(-1)). After 2.5 years of incubation measurements were made of NO(3)(-)-N removal rates, in vitro denitrification rates (DR), factors limiting denitrification (carbon and nitrate availability, dissolved oxygen, temperature, pH, and concentrations of NO(3)(-), nitrite and ammonia), copy number of nitrite reductase (nirS and nirK) and nitrous oxide reductase (nosZ) genes, and greenhouse gas production (dissolved nitrous oxide (N(2)O) and methane), and carbon (TOC) loss. Microbial denitrification was the main mechanism for NO(3)(-)-N removal. Nitrate-N removal rates ranged from 1.3 (pine woodchips) to 6.2 g N m(-3) d(-1) (maize cobs), and were predominantly limited by C availability and temperature (Q(10) = 1.2) when NO(3)(-)-N outlet concentrations remained above 1 mg L(-1). The NO(3)(-)-N removal rate did not depend directly on substrate type, but on the quantity of microbially available carbon, which differed between carbon sources. The abundance of denitrifying genes (nirS, nirK and nosZ) was similar in replicate barrels under cold incubation, but varied substantially under warm incubation, and between substrates. Warm incubation enhanced growth of nirS containing bacteria and bacteria that lacked the nosZ gene, potentially explaining the greater N(2)O emission in

  8. Effect of cropland management and slope position on soil organic carbon pool at the North Appalachian Experimental Watersheds

    Energy Technology Data Exchange (ETDEWEB)

    Hao, Yueli; Lal, Rattan; Owens, Lloyd; Izaurralde, R Cesar C.; Post, W M.; Hothem, Daniel

    2002-12-01

    Soil organic matter is strongly related to soil type, landscape morphology, and soil and crop management practices. Therefore, long-term (15-36-years) effects of six cropland management systems on soil organic carbon (SOC) pool in 0-30 cm depth were studied for the period of 1939-1999 at the North Appalachian Experimental Watersheds (<3 ha, Dystric Cambisol, Haplic Luvisol, and Haplic Alisol) near Coshocton, OH, USA. Six management treatments were: (1) no tillage continuous corn with NPK (NC); (2) no tillage continuous corn with NPK and manure (NTC-M); (3) no tillage corn?soybean rotation (NTR); (4) chisel tillage corn?soybean rotation (CTR); (5) moldboard tillage with corn?wheat?meadow?meadow rotation with improved practices (MTR-I); (6) moldboard tillage with corn?wheat?meadow?meadow rotation with prevalent practices (MTR-P). The SOC pool ranged from 24.5Mgha?1 in the 32-years moldboard tillage corn (Zea mays L.)?wheat (Triticum aestivum L.)?meadow?meadow rotation with straight row farming and annual application of fertilizer (N:P:K = 5:9:17) of 56?112 kg ha?1 and cattle (Bos taurus) manure of 9Mg ha?1 as the prevalent system (MTR-P) to 65.5Mgha?1 in the 36-years no tillage continuous corn with contour row farming and annual application of 170?225 kgNha?1 and appropriate amounts of P and K, and 6?11Mgha?1 of cattle manure as the improved system (NTC-M).

  9. Effects of Long-term Conservation Tillage on Soil Nutrients in Sloping Fields in Regions Characterized by Water and Wind Erosion.

    Science.gov (United States)

    Tan, Chunjian; Cao, Xue; Yuan, Shuai; Wang, Weiyu; Feng, Yongzhong; Qiao, Bo

    2015-12-01

    Conservation tillage is commonly used in regions affected by water and wind erosion. To understand the effects of conservation tillage on soil nutrients and yield, a long-term experiment was set up in a region affected by water and wind erosion on the Loess Plateau. The treatments used were traditional tillage (CK), no tillage (NT), straw mulching (SM), plastic-film mulching (PM), ridging and plastic-film mulching (RPM) and intercropping (In). Our results demonstrate that the available nutrients in soils subjected to non-traditional tillage treatments decreased during the first several years and then remained stable over the last several years of the experiment. The soil organic matter and total nitrogen content increased gradually over 6 years in all treatments except CK. The nutrient content of soils subjected to conservative tillage methods, such as NT and SM, were significantly higher than those in soils under the CK treatment. Straw mulching and film mulching effectively reduced an observed decrease in soybean yield. Over the final 6 years of the experiment, soybean yields followed the trend RPM > PM > SM > NT > CK > In. This trend has implications for controlling soil erosion and preventing non-point source pollution in sloping fields by sacrificing some food production.

  10. The Effect of Computer Games on the Proficiency of the B.Ed. Teacher Trainees in Using the Conventional Expressions in Conversations

    Science.gov (United States)

    Muthiah, Rajendran

    2015-01-01

    The purpose of the study is to assess the effect of computer games on the proficiency of the B.Ed teacher trainees in using the conventional expressions in conversations. The role of technology in language learning has made outdated, drills, grammatical explanations and translation of texts, and the focus is shifted to communication based…

  11. The Sloping Land Conversion Program in China

    DEFF Research Database (Denmark)

    Liu, Zhen

    conversion program. Our results show that SLCP works as a valid external policy intervention on rural livelihood diversification. In addition, the findings demonstrate that there exist heterogeneous effects of SLCP implementation on livelihood diversification across different rural income groups. The lower......By overcoming the barriers that limit access to financial liquidity and human resource, the Sloping Land Conversion Program (SLCP) can promote rural livelihood diversification. This paper examines this effect using a household survey data set spanning the 1999 implementation of the Sloping land...... income group was more affected by the program in terms of income diversification....

  12. 植物纤维毯对道路边坡微生境的影响%Effect of Geotextile on Road Slope Microhabitat

    Institute of Scientific and Technical Information of China (English)

    2016-01-01

    In order to better understand the ecological protection function of geotextiles, comprehensively understand the principle of slope protection, and analyze in-depth the advantages of ecological slope protection of geotextiles, the field experiment is carried out on the slope of Shijiazhuang—Anyang expressway . Taking straw mats, coconut mats and straw coconut mats as the experimental object and the non-woven fabric as the control group, we observed the amount of surface runoff, soil erosion volume, surface soil moisture, soil temperature and soil organic matter content, etc. to analyse the influence of different geotextiles on slope microhabitat. The result shows that (1) 3 kinds of geotextile on the microhabitat of the slope have certain improvement, the soil loss from plots covered with the 3 kinds of geotextile decreased obviously, and the amount of surface runoff decreased in straw mats and straw coconut mats;(2) the 3 kinds of geotextile can reduce the surface soil temperature in the high temperature season, and the cooling effect of straw mats is the best;(3) from the view of the surface soil moisture content, the straw coconut mat is more advantageous to the rain water infiltration, resulting in high soil moisture, and the surface soil moisture loss is slow after rain stopped, so that it is more advantageous to the plant growth;(4) the degradation of 3 kinds of geotextile can increase the soil organic matter content, enhance soil fertility, and improve the soil, the effect of the straw mats is the best;(5) the influence of geotextiles on the soil microhabitat is an improvement, it can promote plant growth, especially it can promote the growth of the roots of the plants.%为更好地了解植物纤维毯的生态防护功能,全面认识其护坡原理,深入分析植物纤维毯的生态护坡优势,依托石安(石家庄—安阳)高速公路展开实地边坡试验.以稻草毯、 稻草椰丝混合毯和椰丝毯为试验对象,以无纺布为对照组

  13. Decision Guide for Roof Slope Selection

    Energy Technology Data Exchange (ETDEWEB)

    Sharp, T.R.

    1988-01-01

    This decision guide has been written for personnel who are responsible for the design, construction, and replacement of Air Force roofs. It provides the necessary information and analytical tools for making prudent and cost-effective decisions regarding the amount of slope to provide in various roofing situations. Because the expertise and experience of the decision makers will vary, the guide contains both basic slope-related concepts as well as more sophisticated technical data. This breadth of information enables the less experienced user to develop an understanding of roof slope issues before applying the more sophisticated analytical tools, while the experienced user can proceed directly to the technical sections. Although much of this guide is devoted to the analysis of costs, it is not a cost-estimating document. It does, however, provide the reader with the relative costs of a variety of roof slope options; and it shows how to determine the relative cost-effectiveness of different options. The selection of the proper roof slope coupled with good roof design, a quality installation, periodic inspection, and appropriate maintenance and repair will achieve the Air Force's objective of obtaining the best possible roofing value for its buildings.

  14. Cost-effective nanoporous Agar-Agar polymer/Nickel powder composite particle for effective bio-products adsorption by expanded bed chromatography.

    Science.gov (United States)

    Asgari, Setareh; Jahanshahi, Mohsen; Rahimpour, Ahmad

    2014-09-26

    In the present work a novel kind of dense nanoporous composite matrix for expanded bed application has been successfully first prepared with Nickel powder as a densifier and was covered with Agar-Agar layer as a skeleton, through the method of water-in-oil emulsification. Agar-Agar is a porous and inexpensive polymer. In order to fabricate cost-effective adsorbent with favorable qualities Agar-Agar polymer was used. Thereafter, the customized composite particle was modified by pseudo-affinity dye-ligand, Reactive Blue 4 (RB4), aimed at preparing a pseudo-affinity adsorbent (RB4-Agar-Ni) for bioprodut adsorption from aqueous solution. Bovine Serum Albumin (BSA) was selected as a model protein to investigate the adsorption behavior in batchwise and expanded bed chromatography, and the obtained results were evaluated with that of Streamline™ (Amersham-Pharmacia Biotech, Sweden). Spherical appearance and porous structure of composite particles were observed by the optical microscope (OM) and scanning electronic microscope (SEM). The results suggested that the matrices followed the logarithmic normal size distribution with the range of 65-300 μm and average diameter of 126.81-151.47 μm, proper wet density of 1.64-2.78 g/ml, water content of 62.74-34%, porosity of 98-90% and pore size of about 38-130 nm. For better comprehension of the impact of solid phase properties on the performance of the expanded bed, the expansion and hydrodynamic properties of a composite matrix with a series of densities was evaluated and estimated by the retention time distribution method (RTD) in an expanded bed and was compared with that of other matrices. According to obtained results the expansion factors under the same fluid velocity decreased by increasing the matrix density. Moreover, the axial dispersion coefficient (Dax) is the most appropriate parameter for evaluating the stability of expanded bed, on various operating conditions, such as different flow velocity, bed expansion

  15. 公路边坡绿化覆盖物水土保持效果试验研究%Effectiveness of soil and water conservation of greening mulch of roadside slope

    Institute of Scientific and Technical Information of China (English)

    骆汉; 赵廷宁; 彭贤锋; 郭宇; 梁超

    2013-01-01

    examine the effects of three kinds of mulch, shade net, non-woven fabrics and straws mat on road slopes in decreasing runoff and soil loss. The aim was to obtain the best effectiveness of soil and water conservation in the process of green construction of road slope. The process of runoff production on the slope was strongly influenced by the effects of the underlying surface conditions. The ANOVA showed that there were significant differences among the hydrological responses of the slopes depending on the different mulch. The surface runoff curves are logarithmic. The highest average runoff coefficient was determined for the bare slope (21.3%). Runoff coefficients of slopes with shade net and non-woven fabrics were 13.5%and 18.9%respectively. Average runoff coefficients were lower on the slope with straw mats (6.4%). The three kinds of mulch were all successful in reducing the runoff rate. The average runoff rates were 4.2 mL/s, 5.8 mL/s and 1.9 mL/s for slopes with shade net, non-woven fabrics and straw mats, respectively, which were all much lower than that of bare slope (6.6 mL/s). The same behavior was observed for the peaks of runoff rate. Some differences were also detected in the sediment concentration in runoff water. The greatest erosion was detected on the bare slope, where average sediment yield was 5.7 g/L and total soil loss was 44.2 g/m2. The soil loss from the slopes covered with shade net and non-woven fabrics was approximately 8 g/m2 and 5 g/m2 respectively. The lowest erosion was determined for the slope covered with straw mats (with 1.0 g/L as an average sediment yield and 1.5 g/m2 as a average total soil loss). Sediment yield data were also higher for the bare slope (5.7 g/L) than for the slopes covered with shade net (2.4 g/L) and non-woven fabrics (1.9 g/L). The same behavior was observed for the peaks of sediment yield:the highest value for the bare slope was 8.1 g/L, and the lowest value for the slope with straw mats was 1.8 g/L. The three kinds

  16. The effect of slope steepness and antecedent moisture content on interrill erosion, runoff and sediment size distribution in the highlands of Ethiopia

    Directory of Open Access Journals (Sweden)

    M. B. Defersha

    2011-07-01

    Full Text Available Soil erosion is a two-phase process consisting of the detachment of individual particles and their transport by the flowing water. This study discusses the results of laboratory experiments in which for three soils, the runoff depth, sediment yield, splash erosion and sediment size were measured. Rainfall intensity, slope and antecedent moisture contents were varied in the experiment. The soil types ranged from clay to sandy clay loam (Alemaya Black soil, Regosols and Cambisols. Rainfall was applied for six sequential 15-min periods with rainfall intensities varying between 55 and 120 mm h−1. The three slopes tested were 9, 25, and 45 %. Results show that as slope increased from 9 to 25 %, splash erosion and sediment yield increased. An increase in slope from 25 to 45 % generally decreases in splash erosion. Sediment yield for one soil increased and one soil decreased with slope and for the third soil the trend was different between the two initial moisture contents. Sediment yield was correlated (r = 0.66 with runoff amounts but not with splash erosion. Interrill erosion models that were based on the flowing water and rainfall intensity fitted the data better than when based on rainfall intensity solely. Models that assume a positive linear relationship between erosion and slope may overestimate sediment yield.

  17. Effects of High-Temperature Preoxidation on the Titanomagnetite Ore Structure and Reduction Behaviors in Fluidized Bed

    Science.gov (United States)

    Sun, Haoyan; Adetoro, Ajala Adewole; Pan, Feng; Wang, Zhen; Zhu, Qingshan

    2017-02-01

    The oxidation behaviors of South Africa (SA) titanomagnetite (TTM) and its effects on the gas solid reduction in the fluidized bed were investigated on the basis of the two-stage short process of direct reduction-electric arc furnace (DR-EAF) melting separation. The results showed that the oxidation phase transformations in the high-temperature range from 1073 K to 1223 K (800 °C to 950 °C) can be divided into two typical processes: with the fast generation of pseudobrookite and with the maghemite generation at the initial stage. The reduction efficiency for SA TTM was improved by the preoxidation treatment, mainly because of the dissociation of titania-ferrous oxides to the easy reducible hematite. However, at a preoxidation temperature higher than 1173 K (900 °C), the improving effect became weak, due to high-temperature sintering and the larger crystallite size of oxidation products. There is an extreme value of the preoxidation influence, and the optimum preoxidation time is different for various temperatures. The reduction metallization degree of SA TTM can be relatively improved by 14.5 and 4.5 pct for the first and second reduction steps, respectively, by 1173 K (900 °C) preoxidation with an optimum time of 30 minutes. Finally, the equilibrium relationship between the metallization degree and the gas reduction potential for TTM ore with preoxidation treatment was built.

  18. Carrier effects on tertiary nitrifying moving bed biofilm reactor: An examination of performance, biofilm and biologically produced solids.

    Science.gov (United States)

    Forrest, Daina; Delatolla, Robert; Kennedy, Kevin

    2016-01-01

    Increasingly stricter ammonia and nitrogen release regulations with respect to wastewater effluents are creating a need for tertiary treatment systems. The moving bed biofilm reactor (MBBR) is being considered as an upgrade option for an increasing number of wastewater treatment facilities due to its small footprint and ease of operation. Despite the MBBRs creation as a system to remove nitrogen, recent research on MBBR systems showing that the system's performance is directly related to carrier surface area and is irrespective of carrier shape and type has been performed exclusively on chemical oxygen demand (COD) removal systems. Furthermore, the influence of carrier type on the solids produced by MBBR systems has also been exclusively studied for COD removal systems. This work investigates the effects of three specific carrier types on ammonia removal rates, biofilm morphology, along with solids production and settleability of tertiary nitrifying MBBR systems. The study concludes that carrier type has no significant effect on tertiary nitrifying MBBR system performance under steady, moderate loading conditions. The research does however highlight the propensity of greater surface area to volume carriers to become clogged under high loading conditions and that the high surface area carriers investigated in this study required longer adjustment periods to changes in loading after becoming clogged.

  19. Effects of 3-day bed rest on physiological responses to graded exercise in athletes and sedentary men

    Science.gov (United States)

    Smorawinski, J.; Nazar, K.; Kaciuba-Uscilko, H.; Kaminska, E.; Cybulski, G.; Kodrzycka, A.; Bicz, B.; Greenleaf, J. E.

    2001-01-01

    To test the hypotheses that short-term bed-rest (BR) deconditioning influences metabolic, cardiorespiratory, and neurohormonal responses to exercise and that these effects depend on the subjects' training status, 12 sedentary men and 10 endurance- and 10 strength-trained athletes were submitted to 3-day BR. Before and after BR they performed incremental exercise test until volitional exhaustion. Respiratory gas exchange and heart rate (HR) were recorded continuously, and stroke volume (SV) was measured at submaximal loads. Blood was taken for lactate concentration ([LA]), epinephrine concentration ([Epi]), norepinephrine concentration ([NE]), plasma renin activity (PRA), human growth hormone concentration ([hGH]), testosterone, and cortisol determination. Reduction of peak oxygen uptake (VO(2 peak)) after BR was greater in the endurance athletes than in the remaining groups (17 vs. 10%). Decrements in VO(2 peak) correlated positively with the initial values (r = 0.73, P exercise respiratory exchange ratios were increased in athletes. Cardiac output was unchanged by BR in all groups, but exercise HR was increased and SV diminished in the sedentary subjects. The submaximal [LA] and [LA] thresholds were decreased in the endurance athletes from 71 to 60% VO(2 peak) (P exercise. These effects were insignificant in the remaining subjects. In conclusion, reduction of exercise performance and modifications in neurohormonal response to exercise after BR depend on the previous level and mode of physical training, being the most pronounced in the endurance athletes.

  20. Effects of pulse-to-pulse residual species on discharges in repetitively pulsed discharges through packed bed reactors

    Science.gov (United States)

    Kruszelnicki, Juliusz; Engeling, Kenneth W.; Foster, John E.; Kushner, Mark J.

    2016-09-01

    Atmospheric pressure dielectric barrier discharges (DBDs) sustained in packed bed reactors (PBRs) are being investigated for conversion of toxic and waste gases, and CO2 removal. These discharges are repetitively pulsed having varying flow rates and internal geometries, which results in species from the prior pulse still being in the discharge zone at the time the following discharge pulse occurs. A non-negligible residual plasma density remains, which effectively acts as preionization. This residual charge changes the discharge properties of subsequent pulses, and may impact important PBR properties such as chemical selectivity. Similarly, the residual neutral reactive species produced during earlier pulses will impact the reaction rates on subsequent pulses. We report on results of a computational investigation of a 2D PBR using the plasma hydrodynamics simulator nonPDPSIM. Results will be discussed for air flowing though an array of dielectric rods at atmospheric pressure. The effects of inter-pulse residual species on PBR discharges will be quantified. Means of controlling the presence of residual species in the reactor through gas flow rate, pulse repetition, pulse width and geometry will be described. Comparisons will be made to experiments. Work supported by US DOE Office of Fusion Energy Science and the National Science Foundation.

  1. Mechanisms of Neuroplasticity and Ethanol's Effects on Plasticity in the Striatum and Bed Nucleus of the Stria Terminalis.

    Science.gov (United States)

    Lovinger, David M; Kash, Thomas L

    2015-01-01

    Long-lasting changes in synaptic function (i.e., synaptic plasticity) have long been thought to contribute to information storage in the nervous system. Although synaptic plasticity mainly has adaptive functions that allow the organism to function in complex environments, it is now clear that certain events or exposure to various substances can produce plasticity that has negative consequences for organisms. Exposure to drugs of abuse, in particular ethanol, is a life experience that can activate or alter synaptic plasticity, often resulting in increased drug seeking and taking and in many cases addiction.Two brain regions subject to alcohol's effects on synaptic plasticity are the striatum and bed nucleus of the stria terminalis (BNST), both of which have key roles in alcohol's actions and control of intake. The specific effects depend on both the brain region analyzed (e.g., specific subregions of the striatum and BNST) and the duration of ethanol exposure (i.e., acute vs. chronic). Plastic changes in synaptic transmission in these two brain regions following prolonged ethanol exposure are thought to contribute to excessive alcohol drinking and relapse to drinking. Understanding the mechanisms underlying this plasticity may lead to new therapies for treatment of these and other aspects of alcohol use disorder.

  2. Geomorphologic mapping in the Ny Ålesund area (Svalbard Island, Norway) for the analysis of geomorphologic effects on rock slopes induced by glacier retreat in climate sensitive High Arctic regions

    Science.gov (United States)

    Miccadei, Enrico; Piacentini, Tommaso; Casacchia, Ruggero; Sparapani, Roberto

    2014-05-01

    The geomorphological effects of glacial retreat, rapidly changing Arctic environments and consequent local temporary permafrost melting are several types of glacial and periglacial landforms (pingos, solifluction, drumlins, etc.) but also debris and rock falls, alluvial fan and glacial outwash development and scarp/slopes retreat and evolution. In this work we have realized a geomorphologic map of rockfalls, landslides, alluvial fans and the slopes and scarps of steep mountainsides in the Ny Ålesund area (Svalbard Island, Norway) focused on the analysis of rock falls as geomorphological effects of glacier retreat, permafrost degradation and higher temperatures on slope processes. The investigation is based on geological and geomorphological field survey, and remote sensing and aerial photo interpretation, The Ny Ålesund area landscape is characterized by rugged non-vegetated mountains only partially covered by glaciers, with steep flanks and rock scarps; the scarps are formed by different types of rocks (intrusive and effusive igneous rocks, marine sedimentary rocks); this landscape is highly affected by debris and rock falls (from scarps and slopes) forming wide talus slopes and by alluvial fan and fluvial outwash (from glaciers), which make the surface sedimentary cover of the island together with rock glaciers and moraine deposits and locally fluvial deposits. The work is focused on the comprehension of the role of different factors in inducing rock falls, alluvial fans, slope/scarps evolution in high geomorphological sensitivity environments (i.e. glacial, periglacial or mountain) including: orography, lithology, rock fracturation, morphostructural setting, meteorological context. The conclusions focus on the possible geomorphological hazards affecting the Ny Ålesund area.

  3. The features of soil aggregation and its eco—environmental effects under different subalpine forests on the east slope of Gongga Mountain,China

    Institute of Scientific and Technical Information of China (English)

    ZHANGBao-hua; HEYu-rong; ZHOUHong-yi; CHENGGen-wei

    2003-01-01

    Structural properties of forest soils have important hydro-ecological function and can influence the soil water-physical characters and soil erosion.The experimental soil samples were obtained in surface horizon (0-10cm) from different subalpine forest types on east slope of Gongga Mountain in the upriver area of Yangtze River China in May 2002.The soil bulk density,porosity,stable infiltration rate,aggregate distribution and particle-size distribution were analyzed by the routine methods in room,and the features and effects on eco-environment of soil aggregation were studied.The results showed that the structure of soil under mixed mature forest is in the best condition and can clearly enhance the eco-environmental function of soil,and the soil structure under the clear-cutting forest is the worst,the others are ranked between them.The study results can offer a basic guidance for the eco-environmental construction in the upper reaches of Yangtze River.

  4. Relief unity emulator and slope stability simulator applied to mass movement occurrence analysis in slope evolution

    Science.gov (United States)

    Colangelo, Antonio C.

    2010-05-01

    This work refers to a part of my "Fellow" thesis "Geomorphosynthesis and Geomorphocinematic applied to slope stability and evolution" (Colangelo, 2007). Relief unity emulator (rue) is a device that permits to synthesize a slope unity by means of a single generatrix profile that determine the initial conditions for application of a set of a geotechnical, hydrological and morphological models. This initial profile is considered in equilibrium with original environmental conditions, and operates in an integrated manner with these models. The aim is to induce a boundary condition on initial profile and produce a new profile: a threshold profile. For this manner and by iterations we generate a set of new profiles that represents, each one, a meta-stable profile, or a descending profile. The evolution of these profiles is in according with the central geomorphologycal concepts of slope retreat, base level change and head retreat. This set of "descending profiles" will be now sliced at topographic equivalent points, that will linked for describe a "topographic equivalence line". The crossing of this kind of isolines with descending profiles composes a 3D slope unity. This descending slope unity is represented by a mesh built for the crossing of these new slope profiles with the topographic equivalence lines and, the result is a four-dimensional meta-stable object integrated to the slope stability simulator (sss). This composite "rue-sss" device operates with 10 main models and 16 variables. The models describe effective stress, shearing resistance, soil saturation level behavior, potential rupture surface depth, critical depth, potential rupture surface critical gradient, critical soil saturation level, top of percolation flow gradient and unit weight of soil. Of this manner, is possible to evaluate effective friction angles and cohesion, critical soil saturation levels, critical gradients for potential rupture surfaces, neutral stress, shear strength, shear stress

  5. On the Effective Thermal Conductivity of Porous Packed Beds with Uniform Spherical Particles

    Science.gov (United States)

    Kandula, Max

    2010-01-01

    Point contact models for the effective thermal conductivity of porous media with uniform spherical inclusions have been briefly reviewed. The model of Zehner and Schlunder (1970) has been further validated with recent experimental data over a broad range of conductivity ratio from 8 to 1200 and over a range of solids fraction up to about 0.8. The comparisons further confirm the validity of Zehner-Schlunder model, known to be applicable for conductivity ratios less than about 2000, above which area contact between the particles becomes significant. This validation of the Zehner-Schlunder model has implications for its use in the prediction of the effective thermal conductivity of water frost (with conductivity ratio around 100) which arises in many important areas of technology.

  6. Overland flow resistances on varying slope gradients and partitioning on grassed slopes under simulated rainfall

    Science.gov (United States)

    Pan, Chengzhong; Ma, Lan; Wainwright, John; Shangguan, Zhouping

    2016-04-01

    It is still unclear how slope steepness (S) and revegetation affect resistance (f) to overland flow. A series of experiments on runoff hydraulics was conducted on granular surfaces (bare soil and sandpaper) and grassed surfaces, including grass plots (GP), GP with litter (GL), and GP without leaves (GS) under simulated rainfall and inflow (30grass plots. A greater f occurred at the gentle and steep slopes for the granular surfaces, while f decreased with increasing slopes for the grass treatments. The different f-S relations suggest that f is not a simple function of S. When Re≈1000, the sowing rye grass with level lines increased f by approximately 100 times and decreased bed shear stress to approximately 5%. The contribution of grass leaves, stems, litter, and grain surface to total resistance in the grass plots were averagely 52%, 32%, 16%, and 1%. The greater resistance from leaves may result from the leaves lying at the plot surface impacted by raindrop impact. These results are beneficial to understand the dynamics of runoff and erosion on hillslopes impacted by vegetation restoration.

  7. Effect of freeboard extension on co-combustion of coal and olive cake in a fluidized bed combustor

    Energy Technology Data Exchange (ETDEWEB)

    Akpulat, O.; Varol, M.; Atimtay, A.T. [Middle East Technical University, Ankara (Turkey). Dept. of Environmental Engineering

    2010-08-15

    In this study, flue gas emissions and combustion efficiencies during combustion and co-combustion of olive cake and coal were investigated in a bubbling fluidized bed. Temperature distributions along the combustion column and flue gas concentrations of O{sub 2}, CO, SO{sub 2} and NOx were measured during combustion experiments. Two sets of experiments were performed to examine the effect of fuel composition, excess air ratio and freeboard extension on flue gas emissions and combustion efficiency. The results of the experiments showed that coal combustion occurs at lower parts of the combustion column whereas olive cake combustion takes place more in the freeboard region. As olive cake percentage in the fuel mixture increased, CO emissions increased, SO{sub 2} and NOx emissions decreased. Additionally, flue gas emissions could be lowered with the freeboard extension while burning biomass or biomass/coal mixtures. Noticeable decrease in CO emissions and slight increase in combustion efficiencies were observed with a column height of 1900 mm instead of 900 mm.

  8. Effect of freeboard extension on co-combustion of coal and olive cake in a fluidized bed combustor.

    Science.gov (United States)

    Akpulat, Onur; Varol, Murat; Atimtay, Aysel T

    2010-08-01

    In this study, flue gas emissions and combustion efficiencies during combustion and co-combustion of olive cake and coal were investigated in a bubbling fluidized bed. Temperature distributions along the combustion column and flue gas concentrations of O(2), CO, SO(2) and NO(x) were measured during combustion experiments. Two sets of experiments were performed to examine the effect of fuel composition, excess air ratio and freeboard extension on flue gas emissions and combustion efficiency. The results of the experiments showed that coal combustion occurs at lower parts of the combustion column whereas olive cake combustion takes place more in the freeboard region. As olive cake percentage in the fuel mixture increased, CO emissions increased, SO(2) and NO(x) emissions decreased. Additionally, flue gas emissions could be lowered with the freeboard extension while burning biomass or biomass/coal mixtures. Noticeable decrease in CO emissions and slight increase in combustion efficiencies were observed with a column height of 1900 mm instead of 900 mm.

  9. On the effect of cross sectional shape on incipient motion and deposition of sediments in fixed bed channels

    Directory of Open Access Journals (Sweden)

    Safari Mir-Jafar-Sadegh

    2014-03-01

    Full Text Available The condition of incipient motion and deposition are of the essential issues for the study of sediment transport. This phenomenon is of great importance to hydraulic engineers for designing sewers, drainage, as well as other rigid boundary channels. This is a study carried out with the objectives of describing the effect of cross-sectional shape on incipient motion and deposition of particles in rigid boundary channels. In this research work, the experimental data given by Loveless (1992 and Mohammadi (2005 are used. On the basis of the critical velocity approach, a new incipient motion equation for a V-shaped bottom channel and incipient deposition of sediment particles equations for rigid boundary channels having circular, rectangular, and U-shaped cross sections are obtained. New equations were compared to the other incipient motion equations. The result shows that the cross-sectional shape is an important factor for defining the minimum velocity for no-deposit particles. This study also distinguishes incipient motion of particles from incipient deposition for particles. The results may be useful for designing fixed bed channels with a limited deposition condition.

  10. Effect of sand bed depth and media age on Escherichia coli and turbidity removal in biosand filters.

    Science.gov (United States)

    Napotnik, Julie A; Baker, Derek; Jellison, Kristen L

    2017-02-17

    The main objective of this study was to build several full-scale biosand filters (BSFs) and assess the long-term (9 month) efficacy for particulate and Escherichia coli removal under simulated real-world usage. Four replicates of three different filter designs were built: the traditional concrete BSF, and two scaled-down versions that use a 5-gal or 2-gal bucket, respectively, as the casing material. The smaller sand bed depths in the bucket-sized filters did not impact filter performance with respect to (i) turbidity and E. coli removal or (ii) effluent levels of turbidity and E. coli. All filters produced effluents with a mean turbidity of <0.6 NTU. In addition, 78%, 74%, and 72% of effluent samples for the concrete, 5-gal, and 2-gal filters, respectively, had E. coli concentrations <1 CFU/100 mL. The bucket-sized filters were found to be a potential alternative to the concrete BSFs for the removal of E. coli and turbidity from drinking water. Since smaller BSFs must be filled more frequently than larger BSFs to produce comparable water volumes, the effect of shorter pause periods on BSF performance should be investigated.

  11. Effects of coal-bed methane discharge waters on the vegetation and soil ecosystem in Powder River Basin, Wyoming

    Science.gov (United States)

    Stearns, M.; Tindall, J.A.; Cronin, G.; Friedel, M.J.; Bergquist, E.

    2005-01-01

    Coal-bed methane (CBM) co-produced discharge waters in the Powder River Basin of Wyoming, resulting from extraction of methane from coal seams, have become a priority for chemical, hydrological and biological research during the last few years. Soil and vegetation samples were taken from affected and reference sites (upland elevations and wetted gully) in Juniper Draw to investigate the effects of CBM discharge waters on soil physical and chemical properties and on native and introduced vegetation density and diversity. Results indicate an increase of salinity and sodicity within local soil ecosystems at sites directly exposed to CBM discharge waters. Elevated concentrations of sodium in the soil are correlated with consistent exposure to CBM waters. Clay-loam soils in the study area have a much larger specific surface area than the sandy soils and facilitate a greater sodium adsorption. However, there was no significant relation between increasing water sodium adsorption ratio (SAR) values and increasing sediment SAR values downstream; however, soils exposed to the CBM water ranged from the moderate to severe SAR hazard index. Native vegetation species density was highest at the reference (upland and gully) and CBM affected upland sites. The affected gully had the greatest percent composition of introduced vegetation species. Salt-tolerant species had the greatest richness at the affected gully, implying a potential threat of invasion and competition to established native vegetation. These findings suggest that CBM waters could affect agricultural production operations and long-term water quality. ?? Springer 2005.

  12. Effects of octahedral molecular sieve on treatment performance, microbial metabolism, and microbial community in expanded granular sludge bed reactor.

    Science.gov (United States)

    Pan, Fei; Xu, Aihua; Xia, Dongsheng; Yu, Yang; Chen, Guo; Meyer, Melissa; Zhao, Dongye; Huang, Ching-Hua; Wu, Qihang; Fu, Jie

    2015-12-15

    This study evaluated the effects of synthesized octahedral molecular sieve (OMS-2) nanoparticles on the anaerobic microbial community in a model digester, expanded granular sludge bed (EGSB) reactor. The addition of OMS-2 (0.025 g/L) in the EGSB reactors resulted in an enhanced operational performance, i.e., COD removal and biogas production increased by 4% and 11% respectively, and effluent volatile fatty acid (VFA) decreased by 11% relative to the control group. The Biolog EcoPlate™ test was employed to investigate microbial metabolism in the EGSB reactors. Results showed that OMS-2 not only increased the microbial metabolic level but also significantly changed the community level physiological profiling of the microorganisms. The Illumina MiSeq high-throughput sequencing of 16S rRNA gene indicated OMS-2 enhanced the microbial diversity and altered the community structure. The largest bacterial genus Lactococcus, a lactic acid bacterium, reduced from 29.3% to 20.4% by abundance in the presence of 0.25 g/L OMS-2, which may be conducive to decreasing the VFA production and increasing the microbial diversity. OMS-2 also increased the quantities of acetogenic bacteria and Archaea, and promoted the acetogenesis and methanogenesis. The X-ray photoelectron spectroscopy illustrated that Mn(IV)/Mn(III) with high redox potential in OMS-2 were reduced to Mn(II) in the EGSB reactors; this in turn affected the microbial community.

  13. In situ strength of coal bed based on the size effect study on the uniaxial compressive strength

    Institute of Scientific and Technical Information of China (English)

    Gonzatti C.; Zorzi L.; Agostini I.M.; Fiorentini J.A.; Viero A.P.; Philipp R.P.

    2014-01-01

    In the early 1990s, the Foundation for Science and Technology of Rio Grande do Sul State (CIENTEC) developed a pioneering study in Brazil, related to the simultaneous mining of multiple coal seams. One of the activities included detailed studies on the geomechanical characterization of materials present in the Irapua coal seam, under exploitation in the A-Sangao Mine, located near the city of Criciuma-SC, within the South-Catarinense coalfield. The goal of the laboratory tests was to define the behavior of the uniaxial compressive strength of the Irapua coal seam and establish a first approximation for the in situ strength value of this coal seam, since existing knowledge is solely based on practical mining experience over the years. Large samples of the coal seam were collected, using special techniques to maintain the integrity of the material, and a set of 56 uniaxial compression tests in cubic specimens, with side length ranging from 4.5 to 31 cm, were conducted in laboratory. This paper describes the experimen-tal techniques used in the assays, and also presents the uniaxial compression strength results obtained. Moreover, important aspects of this type of study are considered, highlighting the size effect for the carbonaceous bed and the estimation of in situ strength values for the Irapua coal seam.

  14. RMS slope of exponentially correlated surface roughness for radar applications

    DEFF Research Database (Denmark)

    Dierking, Wolfgang

    2000-01-01

    In radar signature analysis, the root mean square (RMS) surface slope is utilized to assess the relative contribution of multiple scattering effects. For an exponentially correlated surface, an effective RMS slope can be determined by truncating the high frequency tail of the roughness spectrum...

  15. Centerline Bed Elevation Profile of Sand Bed Channel due to Bar Formation

    Science.gov (United States)

    Tholibon, D. A.; Ariffin, J.; Abdullah, J.; Muhamad, N. S.

    2016-07-01

    Numerous data on bar formation have been accumulated yet the methods to predict bar geometry especially bar height are still insufficient. Objectives of this study to determine the trend in term of a significant difference of centreline bed elevation profile along the longitudinal distance. This can be investigate by carried out an experimental work in an erodible sand bed channel using a large-scale physical river model. The study included the various hydraulic characteristics with steady flow rates and sediment supply. An experimental work consists of four matrices of flow rate and channel width with other variables namely grains size and bed slope were kept constant. Analysis have included the discussion on a significant difference of centreline bed elevation profile along the longitudinal distance. As a conclusion the higher velocity in the smaller channel width have induced erosion of the banks that resulted in elevation increase while the larger flow rates have contributed to higher elevation.

  16. Stability Analysis for Loosened Rock Slope of Jinyang Grand Buddha in Taiyuan, China

    Science.gov (United States)

    SUN, Jinzhong; TIAN, Xiaofu; GUAN, Xudong; YU, Yonggui; YANG, Xiusheng

    On the basis of the status quo of Jinyang Grand Buddha in Taiyuan, some factors such as topography, geological structures, climate, hydrology, and engineering geology that influence the stability of the Buddha slope are considered, and several working situations of the slope that possibly suffered are presented in this article. The Buddha slope stands upright and the rock masses are composed of thick Permian sandstone, which dips slightly inward to the slope. Affected by both the incision of regional joints and the load relief to the free surface, the rock mass of the Buddha slope has turned into loosened blocks. Numerical stability analysis by FLAC-2D on the basis of the strength reduction method reveals that the localized deformation of the rock masses near the vertical surface of the slope may trigger reversing of rock beddings making the back dip slope convert into a dip slope with the possibility of plane sliding failure. Furthermore, the pseudostatic method for the dynamic process and limit equilibrium method for the static process are applied to different working situations of the Buddha slope. The analytical results illustrate that plane sliding failure will not occur when the slope is affected only by seism. However, water filling in the cracks of the loosened rock mass may greatly contribute to the potential plane sliding failure. When horizontal seism-force and hydrostatic pressure are coupled, the Buddha slope can hardly keep stable. Additionally, the loosened rock masses are prone to block toppling failure when influenced by the seism force.

  17. Effectiveness of the GAEC cross-compliance standard Short-term measures for runoff water control on sloping land (temporary ditches and grass strips in controlling soil erosion

    Directory of Open Access Journals (Sweden)

    Paolo Bazzoffi

    2011-08-01

    Full Text Available The agronomic measures made obligatory by the cross-compliance Standard Temporary measures for runoff water control on sloping land included in the Ministry of Agricultural, Food and Forestry Policies (MiPAAF decree on cross compliance until 2008, and by Standard 1.1 Creation of temporary ditches for the prevention of soil erosion in the 2009 decree, certainly appear to be useful for the control of soil erosion and runoff. The efficacy of temporary drainage ditches and of grass strips in controlling runoff and erosion has been demonstrated in trials conducted in field test plots in Italy. When level temporary drainage ditches are correctly built, namely with an inclination of not more than 2.5% in relation to the maximum hillslope gradient, they allow the suspended sediment eroded upstream to settle in the ditches, retaining the material carried away on the slope and, as a result, reducing the quantity of sediment delivered to the hydrographic network. In particular, among all the results, the erosion and runoff data in a trial conducted in Guiglia (Modena showed that in corn plots, temporary drainage ditches reduced soil erosion by 94%, from 14.4 Mg ha-1 year-1 (above the limit established by the NRCS-USDA of 11.2 Mg ha-1 year-1 to 0.8 Mg ha-1 year-1 (within the NRCS limit and also within the more restrictive limit established by the OECD of 6.0 Mg ha-1 year-1. With respect to the grass buffer strips the most significant research was carried out in Volterra. This research demonstrated their efficacy in reducing erosion from 8.15 Mg ha-1 to 1.6 Mg ha-1, which is approximately 5 times less than the erosion observed on bare soil. The effectiveness of temporary drainage ditches was also assessed through the application of the Revised Universal Soil Loss Equation (RUSLE erosion model to 60 areas under the control of the Agency for Agricultural Payments (AGEA in 2009, comparing the risk of erosion in these sample areas by simulating the presence and

  18. Improvement parameters in dynamic compaction adjacent to the slopes

    Institute of Scientific and Technical Information of China (English)

    Elham Ghanbari; Amir Hamidi

    2015-01-01

    Dynamic compaction is a cost-effective method commonly used for improvement of sandy soils. A number of researchers have investigated experimentally and numerically the improvement parameters of soils using dynamic compaction, such as crater depth, improvement depth, and radial improvement, however, these parameters are not studied for improvement adjacent to the slopes or trenches. In this research, four different slopes with different inclinations are modeled numerically using the finite element code ABAQUS, and impact loads of dynamic compaction are applied. The static factors of safety are kept similar for all trenches and determined numerically by application of gravity loads to the slope using strength reduction method (SRM). The analysis focuses on crater depth and improvement region which are compared to the state of flat ground. It can be observed that compacted area adjacent to the slopes is narrower and slightly away from the slope compared to the flat state. Moreover, crater depth increases with increase in slope inclination.

  19. Earth slope reliability analysis under seismic loadings using neural network

    Institute of Scientific and Technical Information of China (English)

    PENG Huai-sheng; DENG Jian; GU De-sheng

    2005-01-01

    A new method was proposed to cope with the earth slope reliability problem under seismic loadings. The algorithm integrates the concepts of artificial neural network, the first order second moment reliability method and the deterministic stability analysis method of earth slope. The performance function and its derivatives in slope stability analysis under seismic loadings were approximated by a trained multi-layer feed-forward neural network with differentiable transfer functions. The statistical moments calculated from the performance function values and the corresponding gradients using neural network were then used in the first order second moment method for the calculation of the reliability index in slope safety analysis. Two earth slope examples were presented for illustrating the applicability of the proposed approach. The new method is effective in slope reliability analysis. And it has potential application to other reliability problems of complicated engineering structure with a considerably large number of random variables.

  20. ElevationSlope_SLOPE1p6M

    Data.gov (United States)

    Vermont Center for Geographic Information — This metadata applies to the following collection area(s): Addison County 2012 1.6m; Missisquoi Upper 2010 1.6m; Missisquoi Lower 2008 1.6m and related SLOPE...

  1. Effects of 3-day bed rest on physiological responses to graded exercise in athletes and sedentary men

    Science.gov (United States)

    Smorawinski, J.; Nazar, K.; Kaciuba-Uscilko, H.; Kaminska, E.; Cybulski, G.; Kodrzycka, A.; Bicz, B.; Greenleaf, J. E.

    2001-01-01

    To test the hypotheses that short-term bed-rest (BR) deconditioning influences metabolic, cardiorespiratory, and neurohormonal responses to exercise and that these effects depend on the subjects' training status, 12 sedentary men and 10 endurance- and 10 strength-trained athletes were submitted to 3-day BR. Before and after BR they performed incremental exercise test until volitional exhaustion. Respiratory gas exchange and heart rate (HR) were recorded continuously, and stroke volume (SV) was measured at submaximal loads. Blood was taken for lactate concentration ([LA]), epinephrine concentration ([Epi]), norepinephrine concentration ([NE]), plasma renin activity (PRA), human growth hormone concentration ([hGH]), testosterone, and cortisol determination. Reduction of peak oxygen uptake (VO(2 peak)) after BR was greater in the endurance athletes than in the remaining groups (17 vs. 10%). Decrements in VO(2 peak) correlated positively with the initial values (r = 0.73, P < 0.001). Resting and exercise respiratory exchange ratios were increased in athletes. Cardiac output was unchanged by BR in all groups, but exercise HR was increased and SV diminished in the sedentary subjects. The submaximal [LA] and [LA] thresholds were decreased in the endurance athletes from 71 to 60% VO(2 peak) (P < 0.001); they also had an earlier increase in [NE], an attenuated increase in [hGH], and accentuated PRA and cortisol elevations during exercise. These effects were insignificant in the remaining subjects. In conclusion, reduction of exercise performance and modifications in neurohormonal response to exercise after BR depend on the previous level and mode of physical training, being the most pronounced in the endurance athletes.

  2. Effect of organic loading rate on a wastewater treatment process combining moving bed biofilm and membrane reactors.

    Science.gov (United States)

    Melin, E; Leiknes, T; Helness, H; Rasmussen, V; Odegaard, H

    2005-01-01

    The effect of moving bed biofilm reactor (MBBR) loading rate on membrane fouling rate was studied in two parallel units combining MBBR and membrane reactor. Hollow fiber membranes with molecular weight cut-off of 30 kD were used. The HRTs of the MBBRs varied from 45 min to 4 h and the COD loading rates ranged from 4.1 to 26.6 g COD m(-2) d(-1). The trans-membrane pressure (TMP) was very sensitive to fluxes for the used membranes and the experiments were carried out at relatively low fluxes (3.3-5.6 l m(-2) h(-1)). Beside the test with the highest flux, there were no consistent differences in fouling rate between the low- and high-rate reactors. Also, the removal efficiencies were quite similar in both systems. The average COD removal efficiencies in the total process were 87% at 3-4 h HRT and 83% at 0.75-1 h HRT. At high loading rates, there was a shift in particle size distribution towards smaller particles in the MBBR effluents. However, 79-81% of the COD was in particles that were separated by membranes, explaining the relatively small differences in the removal efficiencies at different loading rates. The COD fractionation also indicated that the choice of membrane pore size within the range of 30 kD to 0.1 microm has very small effect on the COD removal in the MBBR/membrane process, especially with low-rate MBBRs.

  3. Combined Effects of Dam Removal and Past Sediment Mining on a Relatively Large Lowland Sandy Gravelly Bed River (Vienne River, France).

    Science.gov (United States)

    Rodrigues, S.; Ursache, O.; Bouchard, J. P.; Juge, P.

    2014-12-01

    Dam removal is of growing interest for the management of sediment fluxes, morphological evolution and ecological restoration of rivers. If dam removal experiments are well documented for small streams, examples of lowland and large rivers are scarce. We present the morphological response of a relatively large lowland river (Vienne River, France) to a dam removal. The objective is to understand and quantify the morphological adaptation on a reach of 50 km and over 15 years associated with the dam removal and the presence of ancient sand pits located along the riverbed. This study is based on field data collected during 7 surveys performed between 1998 and 2013. This dataset focuses on bed geometry, sediment grain size, and bedload fluxes. It was combined with a 1D numerical model to assess flow dynamics and sediment transport before and after dam removal. Results show that dam removal triggered both regressive and progressive erosions and that discharges higher than 100 m3.s-1 were sufficient to erode the sandy sediments trapped by the dam whereas gravels were mobilised for discharges higher than 300 m3.s-1. Since 1999, large bedload sediment waves coming from upstream migrated downstream at an average celerity of 2.2 km.year-1 and were trapped by three ancient sand pits located downstream. Some of these pits constitute efficient sediment traps even 15 years after dam removal. As a result, between 2002 and 2013, the slope of the river bed adjusted gently and observed morphological processes were minors compared with the time period between 1998 and 2002.

  4. Effect of Distributor Design on Gas-Liquid Distribution in Monolithic Bed at High Gas/Liquid Ratios

    Institute of Scientific and Technical Information of China (English)

    周媛; AL-DAHHAN Muthanna; DUDUKOVIC Milorad; 刘辉

    2012-01-01

    Experiments were carried out to investigate the liquid flow distribution at high gas/liquid ratios in a cold model monolith bed of a 0.048 m diameter with 62 cells per cm2.Three types of distributor for the liquid distribu-tion were used to evaluate their distribution performance.Local liquid saturation in individual channels was meas-ured using 16 single-point optical fiber probes mounted inside the channels.The results indicate that 1) The optical fiber probe technique can measure phase distribution in the monolith bed;2) Liquid saturation distribution along the radial direction of the monolith bed is not uniform and the extent of non-uniformity depends on the distributor de-sign and phase velocities;and 3) The tube array distributor provides superior liquid distribution performance over the showerhead and nozzle distributors.

  5. Effects of material properties on the competition mechanism of heat transfer of a granular bed in rotary cylinders

    Institute of Scientific and Technical Information of China (English)

    Xie Zhi-Yin; Feng Jun-Xiao

    2013-01-01

    Mixing and heat transfer processes of the granular materials within rotary cylinders play a key role in industrial processes.The numerical simulation is carried out by using the discrete element method (DEM) to investigate the influences of material properties on the bed mixing and heat transfer process,including heat conductivity,heat capacity,and shear modulus.Moreover,a new Péclet number is derived to determine the dominant mechanism of the heating rate within the particle bed,which is directly related to thermal and mechanical properties.The system exhibits a faster heating rate with the increase of ratio of thermal conductivity and heat capacity,or the decrease of shear modulus when inter-particle conduction dominates the heating rate; conversely,it shows a fast-mixing bed when particle convection governs the heating rate.The simulation results show good agreement with the theoretical predictions.

  6. Effects of untreated bed nets on the transmission of Plasmodium falciparum, P. vivax and Wuchereria bancrofti in Papua New Guinea.

    Science.gov (United States)

    Burkot, T R; Garner, P; Paru, R; Dagoro, H; Barnes, A; McDougall, S; Wirtz, R A; Campbell, G; Spark, R

    1990-01-01

    The impact of untreated bed nets on the transmission of human malaria and filariasis in a village in a hyperendemic area of Papua New Guinea was studied. In anopheline mosquitoes, the Plasmodium falciparum sporozoite antigen positivity rate, filarial infection rates and human blood indices dropped significantly after bed nets were introduced. This reduction in human-vector contact did not affect mosquito density as no significant difference in either landing rates or indoor resting catches was found. The number of bed nets in a house and ownership of dogs were factors significantly associated with a reduction in the number of indoor resting mosquitoes. However, the reduction in the P. falciparum sporozoite antigen rate in mosquitoes was not accompanied by a reduction in either malaria parasite or antibody prevalences or titres against the P. falciparum circumsporozoite protein.

  7. The effects of twelve weeks of bed rest on bone histology, biochemical markers of bone turnover, and calcium homeostasis in eleven normal subjects

    Science.gov (United States)

    Zerwekh, J. E.; Ruml, L. A.; Gottschalk, F.; Pak, C. Y.; Blomqvist, C. G. (Principal Investigator)

    1998-01-01

    This study was undertaken to examine the effects of 12 weeks of skeletal unloading on parameters of calcium homeostasis, calcitropic hormones, bone histology, and biochemical markers of bone turnover in 11 normal subjects (9 men, 2 women; 34 +/- 11 years of age). Following an ambulatory control evaluation, all subjects underwent 12 weeks of bed rest. An additional metabolic evaluation was performed after 12 days of reambulation. Bone mineral density declined at the spine (-2.9%, p = 0.092) and at the hip (-3.8%, p = 0.002 for the trochanter). Bed rest prompted a rapid, sustained, significant increase in urinary calcium and phosphorus as well as a significant increase in serum calcium. Urinary calcium increased from a pre-bed rest value of 5.3 mmol/day to values as high as 73 mmol/day during bed rest. Immunoreactive parathyroid hormone and serum 1,25-dihydroxyvitamin D declined significantly during bed rest, although the mean values remained within normal limits. Significant changes in bone histology included a suppression of osteoblastic surface for cancellous bone (3.1 +/- 1.3% to 1.9 +/- 1.5%, p = 0.0142) and increased bone resorption for both cancellous and cortical bone. Cortical eroded surface increased from 3.5 +/- 1.1% to 7.3 +/- 4.0% (p = 0.018) as did active osteoclastic surface (0.2 +/- 0.3% to 0.7 +/- 0.7%, p = 0.021). Cancellous eroded surface increased from 2.1 +/- 1.1% to 4.7 +/- 2.2% (p = 0.002), while mean active osteoclastic surface doubled (0.2 +/- 0.2% to 0.4 +/- 0.3%, p = 0.020). Serum biochemical markers of bone formation (osteocalcin, bone-specific alkaline phosphatase, and type I procollagen extension peptide) did not change significantly during bed rest. Urinary biochemical markers of bone resorption (hydroxyproline, deoxypyridinoline, and N-telopeptide of type I collagen) as well as a serum marker of bone resorption (type I collagen carboxytelopeptide) all demonstrated significant increases during bed rest which declined toward normal

  8. Thresholds of flow-induced bed disturbances and their effects on stream metabolism in an agricultural river

    Science.gov (United States)

    O'Connor, Ben L.; Harvey, Judson W.; McPhillips, Lauren E.

    2012-01-01

    Storm-driven flow pulses in rivers destroy and restructure sediment habitats that affect stream metabolism. This study examined thresholds of bed disturbances that affected patch- and reach-scale sediment conditions and metabolism rates. A 4 year record of discharge and diel changes in dissolved oxygen concentrations (ΔDO) was analyzed for disturbances and recovery periods of the ΔDO signal. Disturbances to the ΔDO signal were associated with flow pulses, and the recovery times for the ΔDO signal were found to be in two categories: less than 5 days (30% of the disturbances) or greater than 15 days (70% of the disturbances). A field study was performed during the fall of 2007, which included a storm event that increased discharge from 3.1 to 6.9 m3/s over a 7 h period. During stable flow conditions before the storm, variability in patch-scale stream metabolism values were associated with sediment texture classes with values ranging from −16.4 to 2.3 g O22/d (negative sign indicates net respiration) that bounded the reach-averaged rate of −5.6 g O22/d. Hydraulic modeling of bed shear stresses demonstrated a storm-induced flow pulse mobilized approximately 25% of the bed and reach-scale metabolism rates shifted from −5 to −40 g O22/d. These results suggest that storm-induced bed disturbances led to threshold behavior with respect to stream metabolism. Small flow pulses resulted in partial-bed mobilization that disrupted stream metabolism by increased turbidity with short recovery times. Large flow pulses resulted in full-bed mobilization that disrupted stream metabolism by destroying periphyton habitats with long recovery times.

  9. Comparative non-shivering thermogenesis in adjacent populations of the common spiny mouse (Acomys cahirinus) from opposite slopes: the effects of increasing salinity.

    Science.gov (United States)

    Scantlebury, Michael; Afik, Daniel; Shanas, Uri; Haim, Abraham

    2002-01-01

    We compared non-shivering thermogenesis between two adjacent populations of the common spiny mouse Acomys cahirinus from different habitats, in relation to increasing salinity. Individuals were captured from the north- and south-facing slopes of the same valley, that represent "Mediterranean" and "desert" habitats, respectively. We hypothesized that the two populations of mice would differ in their thermoregulatory capacities, reflecting their need to cope with the environmental stress in each habitat. We measured resting metabolic rate by recording oxygen consumption, body temperature and response to an injection of exogenous noradrenaline. Mice were maintained on diets with increasing levels of salt intake to examine their abilities to cope with increasing osmotic stress. Mice from north-facing slopes generally had a higher resting metabolic rate and a higher increase in oxygen consumption in response to noradrenaline than mice from south-facing slopes. Increasing salinity decreased resting metabolic rate values, body temperature, and oxygen consumption in response to noradrenaline in both populations, and diminished slope-dependant differences. We suggest that these differences could be a result of an ongoing adaptive process to different climatic conditions, typical of the Mediterranean region, that are a demonstrable example of evolution in action.

  10. The Effects of Long Duration Head Down Tilt Bed Rest on Neurocognitive Performance: The Effects of Exercise Interventions

    Science.gov (United States)

    Seidler, R. D.; Mulavara, A. P.; Koppelmans, V.; Erdeniz. B.; Kofman, I. S.; DeDios, Y. E.; Szecsy, D. L.; Riascos-Castaneda, R. F.; Wood, S. J.; Bloomberg, J. J.

    2014-01-01

    We are conducting ongoing experiments in which we are performing structural and functional magnetic resonance brain imaging to identify the relationships between changes in neurocognitive function and neural structural alterations following a six month International Space Station mission and following 70 days exposure to a spaceflight analog, head down tilt bedrest. Our central hypothesis is that measures of brain structure, function, and network integrity will change from pre to post intervention (spaceflight, bedrest). Moreover, we predict that these changes will correlate with indices of cognitive, sensory, and motor function in a neuroanatomically selective fashion. Our interdisciplinary approach utilizes cutting edge neuroimaging techniques and a broad ranging battery of sensory, motor, and cognitive assessments that will be conducted pre flight, during flight, and post flight to investigate potential neuroplastic and maladaptive brain changes in crewmembers following long-duration spaceflight. Success in this endeavor would 1) result in identification of the underlying neural mechanisms and operational risks of spaceflight-induced changes in behavior, and 2) identify whether a return to normative behavioral function following re-adaptation to Earth's gravitational environment is associated with a restitution of brain structure and function or instead is supported by substitution with compensatory brain processes. Our ongoing bed rest participants are also engaging in exercise studies directed by Dr. Lori Ploutz Snyder. In this presentation, I will briefly highlight the existing literature linking exercise and fitness to brain and behavioral functions. I will also overview the metrics from my study that could be investigated in relation to the exercise and control subgroups.

  11. Morphological characteristics of overdeepenings in high-mountain glacier beds

    Science.gov (United States)

    Haeberli, Wilfried; Cochachin, Alejo; Fischer, Urs; Giráldez, Claudia; Linsbauer, Andreas; Salazar, Cesar

    2014-05-01

    Overdeepenings, i.e. closed topographic depressions with adverse slopes in the flow direction, are characteristic for glacier beds and glacially sculpted landscapes. Besides their importance as geomorphological landforms, groundwater bodies and sedimentary archives, they are of increasing interest in relation to climate-induced lake formation in de-glaciating landscapes and to depth erosion under ice age conditions in connection with the long-term safety of radioactive waste repositories in some mid-latitude countries. Quantitative predictions of their shape, distribution and conditions of occurrence, however, remain difficult. One major problem thereby relates to the still unsatisfactory treatment in glacier erosion theory of sediment evacuation at glacier beds, especially by subglacial meltwater. An alternative way of searching for realistic/empirical quantitative estimates is, therefore, to analyse the geometry of well-documented overdeepenings. The present study attempts to do this by combining statistical analyses of (a) detailed bathymetries from recently exposed lakes in the Peruvian Andes, (b) numerous bed overdeepenigs below still existing glaciers of the Swiss Alps and the Himalaya-Karakoram region modelled with a robust shear stress approximation linking surface slope to ice thickness at high resolution, and (c, for comparison) reconstructed overdeepenings produced by ice age glaciers in the Swiss Plateau based on numerous drillings and geophysical soundings. The sample of (a) has the advantage that geometries are exactly measured and only subject to young/small sedimentation effects. Sample (b) allows for a comparison with a modern model calculation and with known glacier characteristics. Sample (c) may provide some insights into the question how safely results from high mountain topography can be transferred to sites with markedly different topographic, climatic and glaciological controls (cold-arid lowland). Where possible, mean and maximum values of

  12. No-rinse, one-step bed bath: the effects on the occurrence of skin tears in a long-term care setting.

    Science.gov (United States)

    Birch, Sharon; Coggins, Terry

    2003-01-01

    As the population ages, the occurrence of skin tears becomes a common concern for those providing care. Skin tears are painful and increase the cost of caring for residents in long-term care facilities. Records of 29 bed-bound residents at a 72-bed, long-term care facility were reviewed to ascertain the effects of changing from using soap and water to a no-rinse formula for bathing on the occurrence of skin tears. The effect of the bathing change on nursing practice, patient care outcomes, and cost of patient care also were examined. When the new bath procedure was used, the number of skin tears decreased from 13 in the first month to one in the fourth month, affecting both caregiver time and cost. The observed reduction in the occurrence of skin tears was estimated to result in an annual decrease in cost $2,446.

  13. Introduction to Bed Bugs

    Science.gov (United States)

    The common bed bug (Cimex lectularius) is a pest – feeding on blood, causing itchy bites and generally irritating their human hosts. EPA and other agencies all consider bed bugs a public health pest, but bed bugs are not known to transmit disease.

  14. Assessment and mapping of slope stability based on slope units: A case study in Yan’an, China

    Indian Academy of Sciences (India)

    Jianqi Zhuang; Jianbing Peng; Yonglong Xu; Qiang Xu; Xinghua Zhu; Wei Li

    2016-10-01

    Precipitation frequently triggers shallow landslides in the Loess Plateau of Shaanxi, China, resulting in loss of life, damage to gas and oil routes, and destruction of transport infrastructure and farmland. To assess the possibility of shallow landslides at different precipitation levels, a method to draw slope units and steepest slope profiles based on ARCtools and a new method for calculating slope stability areproposed. The methods were implemented in a case study conducted in Yan’an, north-west China. High resolution DEM (Digital Elevation Model) images, soil parameters from in-situ laboratory measurements and maximum depths of precipitation infiltration were used as input parameters in the method. Next,DEM and reverse DEM were employed to map 2146 slope units in the study area, based on which the steepest profiles of the slope units were constructed. Combining analysis of the water content of loess, strength of the sliding surface, its response to precipitation and the infinite slope stability equation, a newequation to calculate infinite slope stability is proposed to assess shallow landslide stability. The slope unit stability was calculated using the equation at 10-, 20-, 50- and 100-year return periods of antecedent effective precipitation. The number of slope units experiencing failure increased in response to increasing effective antecedent rainfall. These results were validated based on the occurrence of landslides in recent decades. Finally, the applicability and limitations of the model are discussed.

  15. Studies of the quality of the intraosseous dental implant bed and of thermal effects in implant pathology

    Energy Technology Data Exchange (ETDEWEB)

    Wong, K

    2000-07-01

    Dental implants may offer solutions to problems of tooth loss and removable dentures, avoiding the blighting of sound teeth in conventional bridgework. However, there may be severe problems due to deficient and poor quality host bone, particularly in the maxillary sinus region. The success of particulate irradiated mineralised cancellous allograft (IMCA) in generating new bone in the sinus was analysed using the trephine bone cores removed to create an implant bed. Bone cores were embedded and examined using 3D fluorescence fight microscopy and scanning electron microscopy in the backscattered electron (BSE) mode to study the quantity and the quality [degree of mineralisation] of bone in implant sites. In all graft cases, new bone as immature (woven) or mature (lamellar) bone formed on the surfaces of the allograft. The bone volume fraction was found to be significantly greater within 5 mm height of the host sinus floor. In an extended study, control sinuses grafted with IMCA soaked in saline showed no significant difference to the test side treated with the patient's own serum. IMCA was shown to retain much of its original topographical and morphological characteristics. Biopsy core specimens from other (non-sinus) sites in both maxilla and mandible were treated similarly. The highest mineral density distributions were observed in the mandible, with the lowest in the residual posterior maxilla beneath the sinus floor. A novel quantitative bone quality scale is proposed to include three parameters of bone quality: mineralisation density, bone volume fraction and connectivity. Clinical use of Laser Doppler Flowmetry (LDF) confirmed positive blood flow in grafts, sinus membrane, and oral tissues. A model of heat conduction in dental implants, predicted oral heat to be a possible factor in implant pathology. The effect of temperature on avian osteoclastic resorption in vitro was studied using a volumetric pit assay. Osteoclastic function measured as volumes and

  16. Agglomeration in a fluidized bed using multiple jet streams

    Energy Technology Data Exchange (ETDEWEB)

    Rehmat, A.; Abbasian, J. (Institute of Gas Technology, Chicago, IL (United States)); Kothari, M.; Hariri, H.; Arastoopour, H. (Illinois Inst. of Tech., Chicago, IL (United States))

    1992-01-01

    Tests were conducted to determine the overall temperature distribution, temperature in the vicinity of the jets, and the rate of agglomeration in a fluidized bed containing multiple jet streams. Agglomeration of ash during coal gasification increases carbon utilization efficiency considerably. The agglomeration requires a fluidized-bed reactor with a specially designed distributor equipped with a jet to yield a hot zone confined within the bed. The rate of agglomeration depends upon the size and the intensity of the zone. This rate, and hence the unit capacity, could be increased by adding multiple jets to the distributor. The purpose of this study was to verify this phenomenon. The temperature distribution inside the agglomerating fluidized-bed reactor with a single jet was studied by Hariri et al. Various parameters were involved in agglomeration phenomena -- bed material, fluidization velocity, bed temperature, jet velocity, jet temperature, bed geometry, and distributor geometry. Controlled agglomerates were produced in the fluidized bed when a sloped gas distributor consisting of a central jet and a porous plate was used. Gas at temperatures above the melting temperature of a bed material was introduced into the jet and gas at temperatures below the softening temperature was introduced into the distributor. The rate of agglomerate formation was significantly influenced by an increase in either jet air or auxiliary (grid) air temperature. The extent of agglomeration also depended strongly upon the volume of the hot zone confined within the isotherms with temperatures higher than the melting point of the bed material.

  17. Agglomeration in a fluidized bed using multiple jet streams

    Energy Technology Data Exchange (ETDEWEB)

    Rehmat, A.; Abbasian, J. [Institute of Gas Technology, Chicago, IL (United States); Kothari, M.; Hariri, H.; Arastoopour, H. [Illinois Inst. of Tech., Chicago, IL (United States)

    1992-12-31

    Tests were conducted to determine the overall temperature distribution, temperature in the vicinity of the jets, and the rate of agglomeration in a fluidized bed containing multiple jet streams. Agglomeration of ash during coal gasification increases carbon utilization efficiency considerably. The agglomeration requires a fluidized-bed reactor with a specially designed distributor equipped with a jet to yield a hot zone confined within the bed. The rate of agglomeration depends upon the size and the intensity of the zone. This rate, and hence the unit capacity, could be increased by adding multiple jets to the distributor. The purpose of this study was to verify this phenomenon. The temperature distribution inside the agglomerating fluidized-bed reactor with a single jet was studied by Hariri et al. Various parameters were involved in agglomeration phenomena -- bed material, fluidization velocity, bed temperature, jet velocity, jet temperature, bed geometry, and distributor geometry. Controlled agglomerates were produced in the fluidized bed when a sloped gas distributor consisting of a central jet and a porous plate was used. Gas at temperatures above the melting temperature of a bed material was introduced into the jet and gas at temperatures below the softening temperature was introduced into the distributor. The rate of agglomerate formation was significantly influenced by an increase in either jet air or auxiliary (grid) air temperature. The extent of agglomeration also depended strongly upon the volume of the hot zone confined within the isotherms with temperatures higher than the melting point of the bed material.

  18. SU-C-BRE-02: BED Vs. Local Control: Radiobiological Effect of Tumor Volume in Monte Carlo (MC) Lung SBRT Planning

    Energy Technology Data Exchange (ETDEWEB)

    Pokhrel, D; Badkul, R; Jiang, H; Estes, C; Park, J; Kumar, P; Wang, F [UniversityKansas Medical Center, Kansas City, KS (United States)

    2014-06-15

    Purpose: SBRT with hypofractionated dose schemata has emerged a compelling treatment modality for medically inoperable early stage lung cancer patients. It requires more accurate dose calculation and treatment delivery technique. This report presents the relationship between tumor control probability(TCP) and size-adjusted biological effective dose(sBED) of tumor volume for MC lung SBRT patients. Methods: Fifteen patients who were treated with MC-based lung SBRT to 50Gy in 5 fractions to PTVV100%=95% were studied. ITVs were delineated on MIP images of 4DCT-scans. PTVs diameter(ITV+5mm margins) ranged from 2.7–4.9cm (mean 3.7cm). Plans were generated using non-coplanar conformal arcs/beams using iPlan XVMC algorithm (BrainLABiPlan ver.4.1.2) for Novalis-TX with HD-MLCs and 6MVSRS(1000MU/min) mode, following RTOG-0813 dosimetric guidelines. To understand the known uncertainties of conventional heterogeneities-corrected/uncorrected pencil beam (PBhete/ PB-homo) algorithms, dose distributions were re-calculated with PBhete/ PB-homo using same beam configurations, MLCs and monitor units. Biologically effective dose(BED10) was computed using LQ-model with α/β=10Gy for meanPTV and meanITV. BED10-c*L, gave size-adjusted BED(sBED), where c=10Gy/cm and L=PTV diameter in centimeter. The TCP model was adopted from Ohri et al.(IJROBP, 2012): TCP = exp[sBEDTCD50]/ k /(1.0 + exp[sBED-TCD50]/k), where k=31Gy corresponding to TCD50=0Gy; and more realistic MC-based TCP was computed for PTV(V99%). Results: Mean PTV PB-hete TCP value was 6% higher, but, mean PTV PB-homo TCP value was 4% lower compared to mean PTV MC TCP. Mean ITV PB-hete/PB-homo TCP values were comparable (within ±3.0%) to mean ITV MC TCP. The mean PTV(V99%)had BED10=90.9±3.7%(median=92.2%),sBED=54.1±8.2%(median=53.5%) corresponding to mean MC TCP value of 84.8±3.3%(median=84.9%) at 2- year local control. Conclusion: The TCP model which incorporates BED10 and tumor diameter indicates that radiobiological

  19. North Slope (Wahluke Slope) expedited response action cleanup plan

    Energy Technology Data Exchange (ETDEWEB)

    1994-02-01

    The purpose of this action is to mitigate any threat to public health and the environment from hazards on the North Slope and meet the expedited response action (ERA) objective of cleanup to a degree requiring no further action. The ERA may be the final remediation of the 100-I-3 Operable Unit. A No Action record of decision (ROD) may be issued after remediation completion. The US Department of Energy (DOE) currently owns or administers approximately 140 mi{sup 2} (about 90,000 acres) of land north and east of the Columbia River (referred to as the North Slope) that is part of the Hanford Site. The North Slope, also commonly known as the Wahluke Slope, was not used for plutonium production or support facilities; it was used for military air defense of the Hanford Site and vicinity. The North Slope contained seven antiaircraft gun emplacements and three Nike-Ajax missile positions. These military positions were vacated in 1960--1961 as the defense requirements at Hanford changed. They were demolished in 1974. Prior to government control in 1943, the North Slope was homesteaded. Since the initiation of this ERA in the summer of 1992, DOE signed the modified Hanford Federal Agreement and Consent Order (Tri-Party Agreement) with the Washington Department of Ecology (Ecology) and the US Environmental Protection Agency (EPA), in which a milestone was set to complete remediation activities and a draft closeout report by October 1994. Remediation activities will make the North Slope area available for future non-DOE uses. Thirty-nine sites have undergone limited characterization to determine if significant environmental hazards exist. This plan documents the results of that characterization and evaluates the potential remediation alternatives.

  20. Resonance effects on the dynamics of dense granular beds: achieving optimal energy transfer in vibrated granular systems

    NARCIS (Netherlands)

    Windows-Yule, C.R.K.; Rosato, A.D.; Thornton, A.R.; Parker, D.J.

    2015-01-01

    Using a combination of experimental techniques and discrete particle method simulations, we investigate the resonant behaviour of a dense, vibrated granular system. We demonstrate that a bed of particles driven by a vibrating plate may exhibit marked differences in its internal energy dependent on t

  1. The effect of an experimentally created mussel bed on bird densities and food intake of the Oystercatcher Haematopus ostralegus

    NARCIS (Netherlands)

    Ens, BJ; Alting, D

    1996-01-01

    When an experimental mussel bed was created in 1987 on the mudflats south of Schiermonnikoog, Herring Gulls immediately increased in numbers, consuming starfish and damaged Mussels. The build-up of oyster catcher numbers was more gradual, but persisted for longer. Most Oystercatchers attracted to th

  2. Exposure of bed bugs to metarhizium anisopliae, and the effect of defensive secretions on fungal growth in vitro

    Science.gov (United States)

    Bed bugs Cimex lectularius were treated with conidia of the entomopathogenic fungus Metarhizium anisopliae by topical, spray, and contact exposure. One week post-exposure, inconsistent mortalities were observed, averaging 30% across all treatment groups and replicates. Microscopic examination of top...

  3. Effect of urinations on the ammonia emission from group-housing systems for sows with straw bedding: Model assessment

    NARCIS (Netherlands)

    Groenestein, C.M.; Monteny, G.J.; Aarnink, A.J.A.; Metz, J.H.M.

    2007-01-01

    A model was developed as a tool for designing straw-bedded sow group-housing systems with low ammonia emission. Using mechanistic and empirical relationships it calculates the total ammonia emission by integrating ammonia volatilisations from all the urine pools in the house. The reference data were

  4. Investigation of the baffle effects on reactor of fluidized beds with circulating flow along with ozone decomposition

    Directory of Open Access Journals (Sweden)

    E. Zohrabi

    2016-09-01

    Full Text Available Fluidized beds with circulating flow, as the gas-solid contactors, are widely used in physical and chemical processes such as drying of solids, pharmaceutical industries, coating solids, granulation, and water and wastewater treatment industry. In this study, numerical simulation using FLUENT software was conducted to investigate the distribution of solid particles of fluidized beds with circulating flow. To conduct simulation, Eulerian-Eulerian with the help of kinetic theory of granular flow was used. Various values of particle-wall elastic modulus were studied. After selecting the appropriate model to predict the particles flow behavior, ozone decomposition reaction was carried out in fluidized beds with circulating flow and they were solved by FLUENT software. The results showed that the location of ring baffles has the greatest impact on fluctuation of system pressure drop, and adverse mix of gas and increase of solid materials are tangible by baffles, resulting from regulation of bed and accumulation of circulating particles beside the wall.

  5. Effect of pressure on gas-solid flow behavior in dense gas-fluidised beds: a discrete particle simulation study

    NARCIS (Netherlands)

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

    2002-01-01

    A computational study has been carried out to assess the influence of pressure on the flow structures and regime transitions in dense gas-fluidized beds using the discrete particle simulation (DPS) approach. By employing particle level simulation, the particle–particle–fluid interactions were analyz

  6. Modeling downstream fining in sand-bed rivers. II: Application

    Science.gov (United States)

    Wright, S.; Parker, G.

    2005-01-01

    In this paper the model presented in the companion paper, Wright and Parker (2005) is applied to a generic river reach typical of a large, sand-bed river flowing into the ocean in order to investigate the mechanisms controlling longitudinal profile development and downstream fining. Three mechanisms which drive downstream fining are studied: a delta prograding into standing water, sea-level rise, and tectonic subsidence. Various rates of sea-level rise (typical of the late Holocene) and tectonic subsidence are modeled in order to quantify their effects on the degree of profile concavity and downstream fining. Also, several other physical mechanisms which may affect fining are studied, including the relative importance of the suspended versus bed load, the effect of the loss of sediment overbank, and the influence of the delta bottom slope. Finally, sensitivity analysis is used to show that the grain-size distribution at the interface between the active layer and substrate has a significant effect on downstream fining. ?? 2005 International Association of Hydraulic Engineering and Research.

  7. Critical conditions of bed sediment entrainment due to debris flow

    Directory of Open Access Journals (Sweden)

    M. Papa

    2004-01-01

    Full Text Available The present study describes entrainment characteristics of bed material into debris flow, based on flume tests, numerical and dimensional analyses. Flume tests are conducted to investigate influences of bed sediment size on erosion rate by supplying debris flows having unsaturated sediment concentration over erodible beds. Experimental results show that the erosion rate decreases monotonically with increase of sediment size, although erosion rate changes with sediment concentration of debris flow body. In order to evaluate critical condition of bed sediment entrainment, a length scale which measures an effective bed shear stress is introduced. The effective bed shear stress is defined as total shear stress minus yield stress on the bed surface. The results show that critical entrainment conditions can be evaluated well in terms of Shields curve using the effective bed shear stress instead of a usual bed shear stress.

  8. Diurnal changes in pore water sulfide concentrations in the seagrass Thalassia testudinum beds: the effects of seagrasses on sulfide dynamics.

    Science.gov (United States)

    Lee; Dunton

    2000-12-20

    The dynamics of the seagrass-sulfide interaction were examined in relation to diel changes in sediment pore water sulfide concentrations in Thalassia testudinum beds and adjacent bare areas in Corpus Christi Bay and lower Laguna Madre, Texas, USA, during July 1996. Pore water sulfide concentrations in seagrass beds were significantly higher than in adjacent bare areas and showed strong diurnal variations; levels significantly decreased during mid-day at shallow sediment depths (0-10 cm) containing high below-ground tissue biomass and surface area. In contrast, diurnal variations in sediment sulfide concentrations were absent in adjacent bare patches, and at deeper (>10 cm) sediment depths characterized by low below-ground plant biomass or when the grasses were experimentally shaded. These observations suggest that the mid-day depressions in sulfide levels are linked to the transport of photosynthetically produced oxygen to seagrass below-ground tissues that fuels sediment sulfide oxidation. Lower sulfide concentrations in bare areas are likely a result of low sulfate reduction rates due to low organic matter available for remineralization. Further, high reoxidation rates due to rapid exchange between anoxic pore water and oxic overlying water are probably stimulated in bare areas by higher current velocity on the sediment surface than in seagrass beds. The dynamics of pore water sulfides in seagrass beds suggest no toxic sulfide intrusion into below-ground tissues during photosynthetic periods and demonstrate that the sediment chemical environment is considerably modified by seagrasses. The reduced sediment sulfide levels in seagrass beds during photosynthetic periods will enhance seagrass production through reduced sulfide toxicity to seagrasses and sediment microorganisms related to the nutrient cycling.

  9. Spouted bed drying of Bauhinia forficata link extract: the effects of feed atomizer position and operating conditions on equipment performance and product properties

    Directory of Open Access Journals (Sweden)

    C. R. F. Souza

    2005-06-01

    Full Text Available In this paper the effects of feed atomizer position and operating conditions on equipment performance (accumulation rate, product recovery, elutriation and thermal efficiency and product properties (moisture content, size distribution, flavonoid degradation and flow properties during spouted bed drying of Bauhinia forficata Link extract are evaluated. The parameters studied were the position of the atomizer system (top spray or bottom spray, the inlet temperature of the spouting gas (80 and 150oC and the feed mass flow rate of concentrated extract relative to the evaporation capacity of the dryer, Ws/Wmax (15 to 100%. Higher accumulation rate values were obtained with the atomizer placed at the bottom of the bed. In this configuration, the accumulation rate increases with the increase in the Ws/Wmax ratio. The best drying performance was obtained for the top spray configuration.

  10. Propagated fixed-bed mixed-acid fermentation: Part I: Effect of volatile solid loading rate and agitation at high pH.

    Science.gov (United States)

    Golub, Kristina W; Forrest, Andrea K; Mercy, Kevin L; Holtzapple, Mark T

    2011-11-01

    Countercurrent fermentation is a high performing process design for mixed-acid fermentation. However, there are high operating costs associated with moving solids, which is an integral component of this configuration. This study investigated the effect of volatile solid loading rate (VSLR) and agitation in propagated fixed-bed fermentation, a configuration which may be more commercially viable. To evaluate the role of agitation on fixed-bed configuration performance, continuous mixing was compared with periodic mixing. VSLR was also varied and not found to affect acid yields. However, increased VSLR and liquid retention time did result in higher conversions, productivity, acid concentrations, but lower selectivities. Agitation was demonstrated to be important for this fermentor configuration, the periodically-mixed fermentation had the lowest conversion and yields. Operating at a high pH (∼9) contributed to the high selectivity to acetic acid, which might be industrially desirable but at the cost of lower yield compared to a neutral pH.

  11. Effect of granular activated carbon concentration on the content of organic matter and salt, influencing E. coli activity and survival in fluidized bed disinfection reactor.

    Science.gov (United States)

    Racyte, Justina; Langenhoff, Alette A M; Ribeiro, Ana F M M R; Paulitsch-Fuchs, Astrid H; Bruning, Harry; Rijnaarts, Huub H M

    2014-10-01

    Granular activated carbon (GAC) is used in water treatment systems, typically to remove pollutants such as natural organic matter, volatile organic compounds, chlorine, taste, and odor. GAC is also used as a key component of a new technology that combines a fluidized bed reactor with radio frequency electric fields for disinfection. So far, the effects of GAC on bacteria in these fluidized bed reactors are unclear. This paper describes a systematic study of the physico-chemical changes in five microbial media compositions caused by different concentrations (23-350 g/L) of GAC, and the effects of these physico-chemical changes on the metabolic activity and survival of a model microorganism (Escherichia coli YMc10) in a fluidized bed reactor. The chemical adsorption taking place in suspensions with specific GAC changed nutritional, osmotic, and pH conditions in the investigated microbial media (LB, diluted LB, PBS, diluted PBS, and tap water), leading to a decay of the metabolic activity and survival of E. coli. Especially media that are poor in organic and mineral compounds (e.g., PBS) with suspended GAC showed a concentration decay of 3.5 Log CFU/mL E. coli after 6 h. Organic compounds depletion and severe pH variation were enhanced in the presence of higher GAC concentrations.

  12. Ultrasonic P-wave velocity measurements with variable effective pressure at the boundary between slope basin sediments and the accretionary prism: IODP Expedition 315 Site C0001

    Science.gov (United States)

    Hashimoto, Y.; Knuth, M. W.; Tobin, H. J.; 314/315/316 Scientist, I.

    2008-12-01

    IODP Expedition 315 Site C0001 is located on the hanging wall of the midslope megasplay fault in the Nankai subduction zone off Kii peninsula (SW Japan), and penetrated an unconformity between ~200 m thick slope basin sediments and the accretionary prism. While a down-section porosity increase was clearly observed at the boundary from ~50% to ~60%, logging velocity does not appear to decrease at the boundary, which suggests that different diagenetic processes might exist above and below the boundary. In this study, we conducted ultrasonic P-wave velocity measurements with pore pressure control. We also conducted observations of sediment and chemical analysis. We examined the relationships between the acoustic properties, sediment textures, logging data from IODP Expedition 314 Site C0001 and data from shipboard core analysis. The ultrasonic P-wave velocity measurements were conducted under constant pore pressure (500 kPa) and varying confining pressure to control effective pressure. The confining pressure ranges from 550 kPa to a maximum calculated from the density of overlying sediments (lithostatic pressure - hydrostatic pressure). 8 samples were analyzed, located from ~70 m to ~450 m below the sea floor. P-wave velocity ranges from ~1620 m/s to ~1990 m/s under the hydrostatic pressure condition. These velocities are in good agreement with the logging data. Porosity-velocity relationship in the analyzed data also coincide with that observed in the logging data. Samples shallower than ~300 m fall within previously-defined empirical relationships for normal- and high- consolidation. The deeper samples (at ~370 m and ~450 m below sea floor) show much higher velocity than that predicted by the empirical relationship, suggesting that significant cementation is present in those samples. The textural observations of sediments indicate a decrease in pore space with depth. Quartz and feldspar grains are surrounded by clay mineral matrices. Grain size seems to be almost

  13. Pig manure vermicompost as a component of a horticultural bedding plant medium: effects on physicochemical properties and plant growth.

    Science.gov (United States)

    Atiyeh, R M; Edwards, C A; Subler, S; Metzger, J D

    2001-05-01

    This experiment was designed to characterize the physical, chemical and microbial properties of a standard commercial horticultural, greenhouse container, bedding plant medium (Metro-Mix 360), that had been substituted with a range of increasing concentrations (0%, 5%, 10%, 25%, 50% and 100% by volume) of pig manure vermicompost and to relate these properties to plant growth responses. The growth trials used tomatoes (Lycopersicon esculentum Mill.), grown in the substituted media for 31 days under glasshouse conditions, with seedling growth recorded in 20 pots for each treatment. Half of the tomato seedlings (10 pots per treatment) were watered daily with liquid inorganic fertilizer while the other half received water only. The percentage total porosity, percentage air space, pH and ammonium concentrations of the container medium all decreased significantly, after substitution of Metro-Mix 360 with equivalent amounts of pig manure vermicompost; whereas bulk density, container capacity, electrical conductivity, overall microbial activity and nitrate concentrations, all increased with increasing substitutions of vermicompost. The growth of tomato seedlings in the potting mixtures containing 100% pig manure vermicompost was reduced, possibly as a result of high soluble salt concentrations in the vermicompost and poorer porosity and aeration. The growth of tomato seedlings was greatest after substitution of Metro-Mix 360 with between 25% and 50% pig manure vermicompost, with more growth occurring in combinations of pig manure vermicompost treated regularly with a liquid fertilizer solution than in those with no fertilizer applied. Some of the growth enhancement in these mixtures seemed to be related to the combined effects of improved porosity, aeration and water retention in the medium and the high nitrate content of the substrate, which produced an increased uptake of nitrogen by the plant tissues, resulting in increased plant growth. When the tomato seedlings were

  14. On device design for steep-slope negative-capacitance field-effect-transistor operating at sub-0.2V supply voltage with ferroelectric HfO2 thin film

    OpenAIRE

    Masaharu Kobayashi; Toshiro Hiramoto

    2016-01-01

    Internet-of-Things (IoT) technologies require a new energy-efficient transistor which operates at ultralow voltage and ultralow power for sensor node devices employing energy-harvesting techniques as power supply. In this paper, a practical device design guideline for low voltage operation of steep-slope negative-capacitance field-effect-transistors (NCFETs) operating at sub-0.2V supply voltage is investigated regarding operation speed, material requirement and energy efficiency in the case o...

  15. Slope stability hazard management systems

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Weather-related geo-hazards are a major concern for both natural slopes and man-made slopes and embankments.Government agencies and private companies are increasingly required to ensure that there is adequate protection of sloping surfaces in order that interaction with the climate does not produce instability. Superior theoretical formulations and computer tools are now available to address engineering design issues related to the near ground surface soil-atmospheric interactions. An example is given in this paper that illustrates the consequences of not paying adequate attention to the hazards of slope stability prior to the construction of a highway in South America. On the other hand, examples are given from Hong Kong and Mainland China where significant benefits are derived from putting in place a hazard slope stability management system. Some results from a hazard management slope stability study related to the railway system in Canada are also reported. The study took advantage of recent research on unsaturated soil behaviour and applied this information to real-time modelling of climatic conditions. The quantification of the water balance at the ground surface, and subsequent infiltration, is used as the primary tool for hazard level assessment. The suggested hazard model can be applied at either specific high risk locations or in a more general, broad-based manner over large areas. A more thorough understanding of unsaturated soil behaviour as it applies to near ground surface soils,along with the numerical computational power of the computer has made it possible for new approaches to be used in slope hazard management engineering.

  16. Experiences with Rice Grown on Permanent Raised Beds:Effect of Crop Establishment Techniques on Water Use, Productivity, Profitability and Soil Physical Properties

    Institute of Scientific and Technical Information of China (English)

    R.K.NARESH; S.S.TOMAR; Dipender KUMAR; Samsher; Purushottam; S.P.SINGH; Ashish DWIVEDI; Vineet KUMAR

    2014-01-01

    In recent years, conventional rice production technologies have been leading to deterioration of soil health and declining farm profitability due to high inputs of water and labor. Conservation agriculture (CA) based resource-conserving technologies i.e. zero-tillage (ZT), raised-bed planting and direct-seeded rice (DSR) have shown promise as alternatives to conventional production technologies to overcome these problems. Present study was undertaken during 2009-2012 to establish an understanding of how permanent raised bed cropping system could be practiced to save water at the field application level to improve water productivity and also have the capability to enhance productivity, profitability and soil physical quality. The results showed that among different crop establishment techniques, conventional-tilled puddle transplanted rice (CT-TPR) required 14%-25% more water than other techniques. Compared with the CT-TPR system, zero till direct-seeded rice (ZT-DSR) consumed 6%-10%less water with almost equal system productivity and demonstrated higher water productivity. Wide raised beds saved about 15%-24% water and grain yield decrease of about 8%. Direct-seeded rice after ZT or reduced tillage or on unpuddled soil provided more net income than CT-TPR. The CT-TPR system had higher bulk density and penetration resistance due to compaction caused by the repeated wet tillage in rice. The steady-state infiltration rate and soil aggregation (> 0.25 mm) were higher under permanent beds and ZT and lower in the CT-TPR system. Under CT-TPR, soil aggregation was static across seasons, whereas it improved under no-till and permanent beds. Similarly, mean weight diameter of aggregates was higher under ZT and permanent beds and increased over time. The study reveals that to sustain the rice productivity, CA-based planting techniques can be more viable options. However, the long-term effects of these alternative technologies need to be studied under varying agro-ecologies in

  17. Area utilization efficiency of a sloping heliostat system for solar concentration.

    Science.gov (United States)

    Wei, L Y

    1983-02-15

    Area utilization efficiency (AUE) is formulated for a sloping heliostat system facing any direction. The effects of slope shading, incidence factor, sun shading, and tower blocking by the mirrors are all taken into account. Our results show that annually averaged AUEs calculated for heliostat systems (1) increase with tower height at low slope angles but less rapidly at high slopes, (2) increase monotonically with slope angle and saturate at large slopes for systems facing due south, (3) reach a maximum at a certain slope for systems facing other directions than due south, and (4) drop sharply at slopes greater than a certain value for systems facing due east or west due to slope shading effect. The results are useful for solar energy collection on nonflat terrains.

  18. [Effect of hypodynamia on the hemomicrocirculatory bed of the triceps muscle and brachial fascia in the rat].

    Science.gov (United States)

    Nikitin, M V; Shafikova, L F

    1984-10-01

    By means of amputation of the forearm (the place of the brachial musculus attachment is kept intact) in 30 male rats certain conditions are produced for decreasing force activity in the m. triceps brachii. Anatomical changes in structure and in distribution of links of the hemomicrocirculatory bed (HMCB) are followed in the medial head of the muscle and in the fascia covering it. Time of observations - 1-60 days. The sections of the muscles and some parts of the fascia are impregnated with silver nitrate solution. The greatest changes are observed to occur in the capillary-venular links of the HMCB during the interval of 1.14-4.5 days and are manifested as initial congestion of venous blood in these links. Later (4.5-15.3 and further 60 days) together with stable dilatation of all venous components of the blood bed certain qualitative changes take place in the arteriolar links of the HMCB.

  19. Effect of fouling on the capacity and breakthrough characteristics of a packed bed ion exchange chromatography column.

    Science.gov (United States)

    Siu, Sun Chau; Baldascini, Helen; Hearle, David C; Hoare, Mike; Titchener-Hooker, Nigel J

    2006-05-01

    This study examined the impact of fouling with yeast homogenate on capacity and breakthrough performance of an ion exchange packed bed column. Column performance was assessed by analysis of breakthrough curves obtained with BSA as a test protein. The overall impact of fouling on breakthrough performance depended heavily on the level of clarification of the feed stream. Challenging the column with particulate-free homogenate caused no change in column performance. Loading successive small volumes of poorly clarified homogenate, interspersed with frequent column salt washes, did not alter significantly the column capacity. By contrast, when the column was challenged with an equivalent cumulative volume of poorly clarified homogenate, dynamic binding capacity decreased significantly and changes in breakthrough curves suggested increased intraparticle and external mass transfer limitations. These changes were ascribed to deposition of solid particulates in void spaces in the bed and colloidal contaminants in the bead pores.

  20. Effect of change in patient′s bed angles on pain after coronary angiography according to vital signals

    Directory of Open Access Journals (Sweden)

    Mohamad Amin Younessi Heravi

    2015-01-01

    Full Text Available Background: One of the most common and important diagnostic methods for the detection of heart diseases is coronary angiography. The aim of this study was to determine the optimum angle of the bed by using vital signals to optimize the patient′s position after the angiography. Materials and Methods: This study was a randomized clinical trial (RCT on participants after angiography who were divided into five groups. The first group was placed routinely in a supine position. In the other groups, all of the patients were placed in bed by angle 15°, 30°, 45°, and 60° upward. In each group, vital signals were measured that included blood pressure, percent of blood oxygen saturation, heart rate, respiratory rate, and temperature. All of measured data compared with the pain score has been achieved from numerical pain scale. The data were analyzed by descriptive statistics method, variance analysis, and post hoc tests in the Statistical Package for the Social Sciences (SPSS software, version 16. Estimation of the relationship was done by MATLAB version 2011. The level of significance was considered to be 0.05. Results: In various groups, there was no significance difference in demographic variables such as gender, age, height, and weight. The mean of pain score, heart rate, systolic blood pressure, and respiratory rate changed significantly (P 0.05. It showed linear changes between pain and systolic blood pressure, respiratory rate, and heart rate changes. A dramatic reduction was also seen in systolic blood pressure, respiratory rate, heart rate, and also pain at an angle of 45 ° . Conclusion: This study showed that, 45 ° was the best angle of the bed to optimize the patient′s position after the procedure, based on his/her vital signs and pain score. Thus, in order to relive pain, this change in bed angle is advised to be planned by postangiography nurses in patients after coronary angiography.

  1. Displacement Damage Effects in Solar Cells: Mining Damage From the Microelectronics and Photonics Test Bed Space Experiment

    Science.gov (United States)

    Hardage, Donna (Technical Monitor); Walters, R. J.; Morton, T. L.; Messenger, S. R.

    2004-01-01

    The objective is to develop an improved space solar cell radiation response analysis capability and to produce a computer modeling tool which implements the analysis. This was accomplished through analysis of solar cell flight data taken on the Microelectronics and Photonics Test Bed experiment. This effort specifically addresses issues related to rapid technological change in the area of solar cells for space applications in order to enhance system performance, decrease risk, and reduce cost for future missions.

  2. Effects of the updated national emission regulation in China on circulating fluidized bed boilers and the solutions to meet them.

    Science.gov (United States)

    Li, Jingji; Yang, Hairui; Wu, Yuxin; Lv, Junfu; Yue, Guangxi

    2013-06-18

    The advantage of circulating fluidized bed (CFB) boilers in China is their ability to utilize low rank coal with low cost emission control. However, the new National Emission Regulation (NER) issued in early 2012 brings much more stringent challenges on the CFB industries, which also causes much attention from other countries. Based on the principle of a CFB boiler and previous operating experience, it is possible for the CFB boilers to meet the new NER and maintain the advantage of low cost emission control, while, more influences should be considered in their design and operation. To meet the requirement of the new NER, the fly ash collector should adopt a bag house or combination of electrostatic precipitator and bag filter to ensure dust emissions of less than 30 mg · Nm(-3). For SO2 emission control, the bed temperature should be strictly lower than 900 °C to maintain high reactivity and pores. The limestone particle size distribution should be ranged within a special scope to optimize the residence time and gas-solid reaction. At the same time, the injecting point should be optimized to ensure fast contact of lime with oxygen. In such conditions, the desulfurization efficiency could be increased more than 90%. For lower sulfur content fuels (bed temperature lower than 900 °C for fuels with low volatiles content (circulating ash, the efficiency of SNCR could reach as high as 70%. The Hg emission of CFB is very low for the new NER due to its innate property.

  3. Effect of particle shape of active pharmaceutical ingredients prepared by fluidized-bed jet-milling on cohesiveness.

    Science.gov (United States)

    Fukunaka, Tadashi; Sawaguchi, Kohta; Golman, Boris; Shinohara, Kunio

    2005-05-01

    Milling is a common procedure to improve bioavailability of many active pharmaceutical ingredients (APIs), which typically have low solubility in water. But such micronization can yield an increase in the cohesiveness of particles. Although particle cohesiveness is desirable for tablet strength in the subsequent formulation process, increased particle cohesiveness can lead to operational difficulties in a milling equipment due to compaction of particles inside. In this article, the impact of milling via a fluidized-bed jet-mill on the cohesive strength and interparticle force was studied using Ethenzamide as a pharmaceutical model compound. As a result, the particle shape was found to affect both the tensile strength of powder bed and the interparticle cohesive force. A powder bed, having relatively high void fraction by direct tensile test, shows a positive correlation between the cohesive force and the particle sphericity, while powders with low void fraction by diametral compression test show a positive correlation between the cohesive force and the angularity of the particle.

  4. ElevationSlope_SLOPE0p7M

    Data.gov (United States)

    Vermont Center for Geographic Information — This metadata applies to the following collection area(s): Windham County 2015 0.7m; Eastern VT 2014 0.7m; Rutland/GI Counties 2013 0.7m and related SLOPE datasets....

  5. Slope spectrum variation in a simulated loess watershed

    Science.gov (United States)

    Li, Fayuan; Tang, Guoan; Wang, Chun; Cui, Lingzhou; Zhu, Rui

    2016-06-01

    A simulated loess watershed, where the loess material and relief properly represent the true loess surface, is adopted to investigate the variation in slope spectrum with loess watershed evolution. The evolution of the simulated loess watershed was driven by the exogenetic force of artificial rainfall. For a period of three months, twenty artificial rainfall events with different intensities and durations were carried out. In the process, nine DEM data sets, each with 10 mm grid resolution, were established by the method of close-range photogrammetry. The slope spectra were then extracted from these DEMs. Subsequent series of carefully designed quantitative analyses indicated a strong relationship between the slope spectrum and the evolution of the simulated loess watershed. Quantitative indices of the slope spectrum varied regularly following the evolution of the simulated loess watershed. Mean slope, slope spectrum information entropy ( H), terrain driving force ( T d ), Mean patch area ( AREA_MN), Contagion Index ( CONTAG), and Patch Cohesion Index ( COHESION) kept increasing following the evolution of the simulated watershed, while skewness ( S), Perimeter-Area Fractal Dimension ( PAFRAC), and Interspersion and Juxtaposition Index ( IJI) represented an opposite trend. All the indices changed actively in the early and active development periods, but slowly in the stable development periods. These experimental results indicate that the time series of slope spectra was able to effectively depict the slope distribution of the simulated loess watershed, thus presenting a potential method for modeling loess landforms.

  6. Study of Slope Reinforcement Force Based on FLAC

    Institute of Scientific and Technical Information of China (English)

    HUANG Xian-wu; MAO xian-biao; MIAO Xie-xing; CHEN Zhan-qing

    2006-01-01

    A slope will slide if the unbalanced force does not tend to zero when the stability of the slope is analyzed with the help of FLAC. Thus the ultimate reason of slope sliding is the unbalanced force determined by FLAC. The slope will remain stable if the unbalanced force is counterbalanced by a reinforcement force which is produced by a suitable reinforcement method. In this paper, the stability of the slope was analyzed by using FLAC, and the unbalanced force of the slope was obtained through the FISH function in FLAC. According to the equilibrium conditions, the relationship between the reinforcement force and unbalanced force was derived and accordingly the reinforcement force was determined. The reinforcement design was adopted by using pre-stressed anchor bars on the basis of the reinforcement force. An example is used to show that the effect of slope reinforcement based on the reinforcement force is safe and economical. The method doesn't need to suppose a sliding surface to obtain the reinforcement force, and it is also clear in physical meaning. So this method realized the organic unification of the stability analysis and the slope reinforcement

  7. INFLUENCE OF LEAF AREA INDEX (LAI ON SLOPE STABILITY

    Directory of Open Access Journals (Sweden)

    Tymoteusz Adam Zydroń

    2016-09-01

    Full Text Available Determination of effect of the leaf area ratio on the results of slope stability calculation of one of the landslide's prone slope of in the Pogórze Wiśnickie was presented in the paper. The calculations were carried out in modules Vadose/W and SLOPE/W of package GeoStudio 2012. The calculations involved the integration of rainfall infiltration process and slope stability calculations. As a result, the calculations allow to determinate precipitation conditions (time and accumulated precipitation height causing slope failure (i.e. rainfall threshold. The calculation results showed significant impact of LAI on the results of modeling. It was revealed, that LAI values in range 1-3, corresponding to the grass vegetation, contribute in long-term to accumulation of precipitation within slope, which limits its retention ability when intense rainfalls occur. In turn, the leaf are index LAI = 5, corresponding to the coverage of trees, increase the retentive capacity of the soil, which resulting in delayed response of slope on rainfall with in comparison to an area covered with grass plants. It was also found significant impact of moisture content conditions on rainfall threshold. It was revealed that in case of analyzed slope threshold rainfall can be comprised from 90 mm to over 700 mm.

  8. Long Duration Head Down Tilt Bed Rest and Spaceflight Effects on Neurocognitive Performance: Extent, Longevity and Neural Bases

    Science.gov (United States)

    Seidler, R. D.; Mulavara, A. P.; Koppelmans, V.; Cassady, K.; Yuan, P.; Kofman, I. S.; De Dios, Y. E.; Riascos-Castaneda, R. F.; Wood, S. J.; Bloomberg, J. J.

    2017-01-01

    We have recently completed a long duration head down tilt bed rest (HDBR) study in which we performed structural and functional magnetic resonance brain imaging to identify the relationships between changes in neurocognitive function and neural structural alterations in a spaceflight analog environment. We are also collecting the same measures in crewmembers prior to and following a six month International Space Station mission. We will present data demonstrating that bed rest resulted in functional mobility and balance deterioration with recovery post-HDBR. We observed numerous changes in brain structure, function, and connectivity relative to a control group which were associated with pre to post bed rest changes in sensorimotor function. For example, gray matter volume (GMv) increased in posterior parietal areas and decreased in frontal regions. GMv increases largely overlapped with fluid decreases and vice versa. Larger increases in precentral gyrus (M1)/ postcentral gyrus (S1+2) GMv and fluid decreases were associated with smaller balance decrements. Vestibular activation in the bilateral insular cortex increased with bed rest and subsequently recovered. Larger increases in vestibular activation in multiple brain regions were associated with greater decrements in balance and mobility. We found connectivity increases between left M1 with right S1+2 and the superior parietal lobule, and right vestibular cortex with the cerebellum. Decreases were observed between right Lobule VIII with right S1+2 and the supramarginal gyrus, right posterior parietal cortex (PPC) with occipital regions, and the right superior posterior fissure with right Crus I and II. Connectivity strength between left M1 and right S1+2/superior parietal lobule increased the most in individuals that exhibited the least balance impairments. In sum, we observed HDBR-related changes in measures of brain structure, function, and network connectivity, which correlated with indices of sensorimotor

  9. Observation and Research on Gravitational Erosion Process of Bank Slopes in Headstream Area of Jiangjia Ravine, Yunnan, China

    Institute of Scientific and Technical Information of China (English)

    FENG Zi-li; CUI Peng; CHEN Xiao-qin; CHEN Jie; ZHU Yin-yan

    2005-01-01

    To reveal the gravitational erosion process in the headstream area of Jiangjia Ravine, continuous observation was conducted duing the rainy season. The observation and research show that the change of water content of the bank slope lags the precipitation process, the infiltration water concentrates mainly in the shallow layer of the bank slope, also the bank slope was unsaturated, the floods and debris flows in the gully down cut the gully bed, and scour the foot of the bank slope. These results in many collapses, which is the main type of gravitational erosion process, and it provides large amounts of loose solid materials for the eruption of debris flows.

  10. Udder health in a Danish compost bedded pack barn

    DEFF Research Database (Denmark)

    Svennesen, Line; Enevoldsen, Carsten; Bjerg, Bjarne Schmidt;

    Besides welfare advantages of the compost bedded pack system (CBP) there could be a negative effect of the organic bedding on udder health. Our objectives were to evaluate the effects of a CBP on udder health compared to a free stall system (FS) with sand bedded cubicles. Within the same Danish...

  11. Eastern slopes grizzly bear project

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2001-01-01

    The cumulative effects of human activities on the grizzly bears in the central Canadian Rockies are not well known. As a result, a project was initiated in 1994 to address the urgent requirement for accurate scientific information on the habitat and populations of grizzly bears in the area of the Banff National Park and Kananaskis Country. This area is probably the most heavily used and developed area where the grizzly still survives. The information gathered throughout the course of this study will be used to better protect and manage the bears and other sensitive carnivores in the region. Using telemetry, researchers are monitoring 25 grizzly bears which were radio-collared in a 22,000 square-kilometer area in the upper Bow Valley drainage of the eastern Alberta slopes. The researchers involved in the project are working with representatives from Husky Oil and Talisman Energy on the sound development of the Moose Mountain oil and gas field without adversely affecting the grizzly bear population. Information collected over seven years indicated that the grizzly bears have few and infrequent offspring. Using the information gathered so far, the location of the Moose Mountain to Jumping Pound pipeline was carefully selected, since the bears recover very slowly from high mortality, and also considering that the food and cover had already been compromised by the high number of roads, trails and other human activities in the area. The status of the population and habitat of the grizzly bear will be assessed upon the conclusion of the field research phase in 2001. Models will be updated using the data obtained during eight years and will assist in the understanding of complex variables that affect grizzly bears.

  12. Studies on Dynamic Response of Loess Slope Under Effects of Construction Vibration Load%施工振动荷载作用下黄土边坡动力响应研究

    Institute of Scientific and Technical Information of China (English)

    马鹏; 杨丹; 李伟

    2014-01-01

    黄土地层因其特殊性,常给工程带来不利影响。为此工程中采取多种措施进行加固。但加固施工产生的振动常会引起边坡坍塌。为了深入研究黄土边坡对施工振动荷载的动力响应,文章以郑西客运专线吕家崖隧道入口处路堑边坡为测试分析对象,在DDC桩施工振动荷载作用下,研究黄土边坡动力响应特征。在现场对水平路基表面和路堑边坡内振动波的振动幅值进行了测量,分析了水平路基表面和路堑边坡内振动波的振幅放大系数和振动能量比,并采用FLAC3D模拟施工振动荷载作用下,边坡的动力响应特征。研究结果表明,黄土边坡对振动存在较强的动力响应,对振动幅值、振动速度幅值存在放大效应,说明在强夯、打桩等施工振动荷载作用下,黄土边坡稳定性受到较大影响,特别是变坡点、坡顶等突出位置容易产生破坏,设计和施工中应给予足够重视。%The particularity of the loess stratum often brings adverse effects to projects, therefore, a lot of reinforcement measures are adopted, but the vibration caused by strengthening construction may cause collapse of side slope. In order to study the dynamic response of loess slope from construction vibration load,the cutting slope at the entrance of Lvjiaya Tunnel on Zhengzhou-Xi’an Passenger Line is chosen for test and analysis. This paper studies the characteristics of lo-ess slope dynamic response under vibrating load caused by DDC piles construction, and FLAC3D is adopted for simulating the dynamic response characteristics under construction vibration load. Results show that the dynamic response of vibra-tion was more strong in loess slope,and there is amplification effect on vibration amplitude and vibration energy, which illustrates that the stability of loess slope will be affected by construction vibrating load of dynamic compaction or piling etc. Especially the prominent

  13. An Extended Mild-Slope Equation

    Institute of Scientific and Technical Information of China (English)

    PAN Junning; HONG Guangwen; ZUO Qihua

    2000-01-01

    On the assumption that the vortex and the vertical velocity component of the current are small, a mild-slope equation for wave propagation on non-uniform flows is deduced from the basic hydrodynamic equations, with the terms of ( h h)2 and /2h h included in the equation. The terms of bottom friction, wind energy input and wave nonlinearity are also introduced into the equation. The wind energy input functions for wind waves and swells are separately considered by adopting Wen′s (1989) empirical formula for wind waves and Snyder′s observation results for swells. Thus, an extended mild-slope equation is obtained, in which the effects of refraction, diffraction, reflection, current, bottom friction, wind energy input and wave nonlinearity are considered synthetically.

  14. Study on Division and Correlation of Red Beds Based on Climate Change Feature: a Case Study on the Southern Slope of Dongying Depression%基于气候变化特征的红层划分对比——以东营凹陷南坡为例

    Institute of Scientific and Technical Information of China (English)

    贺振建; 刘书会; 王长轩; 李慧; 张存霞; 何青芳

    2012-01-01

    首次利用气候变化特征,对由于缺少特征古生物化石资料而长期难以进行地层划分的东营凹陷南坡始新统沙河街组四段下亚段—孔店组一段的红层进行了有效划分.采用基于孢粉化石Ephedripites相对含量约束下的测井数据法恢复相对古气候变化,首先根据Ephedripites相对含量的变化确定气候变化拐点(最干旱点)的位置段,再根据能谱测井数据或常规测井数据计算出的连续粘土矿物组成确定气候拐点的具体点,即为层位界线.根据标准井测井数据建立的数学模型,可以对该井附近新钻探井的红层进行划分对比,其科学性、合理性已被之后的勘探成果所证实.该方法为缺少古生物化石数据的“哑地层”划分提供了一种新思路.%According to the characteristics of the climate change, the red beds from the Es4"1""1櫁Ekl (the Lower Sub -Member of the 4th Member, Shahejie Formation, to the 1st Member, Kongdian Formation, Eocene) in Dongying Depression are availably divided, which have not been divided for a long time because of lacking referential fossils. The relative climate change is recovered based on logging data in combination with the relative content of Ephedripites. At first, according to the relative content of Ephedripites, the depth section of the inflection point of the climate change is defined. Then, based on continuous clay mineral contents which are determined by natural gamma ray spectrometry log data or conventional log data, the concrete depth of the inflection point of the climate is thereby defined, which is recognized as the boundary in the red beds. By the model which from standard well log data, red beds in other new wells nearby can also be divided. The scientific and rational method has been proved by afterward exploration. This method provides a new thought in dividing the fossil barren-beds.

  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

    Science.gov (United States)

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

    2016-09-01

    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 currents are above 0.5 m s-1, while long bed waves occur in regions where the maximum tidal current velocity is slightly above the critical velocity for sand erosion and the current is elliptical. An idealized nonlinear numerical model was developed to improve the understanding of the initial formation of these bedforms. The model governs the feedbacks between tidally forced depth-averaged currents and the sandy bed on the outer shelf. The effects of different formulations of bed shear stress and sand transport, tidal ellipticity and different tidal constituents on the characteristics of these bedforms (growth rate, wavelength, orientation of the preferred bedforms) during their initial formation were examined systematically. The results show that the formulations for bed shear stress and slope-induced sand transport are not critical for the initial formation of these bedforms. For tidal sand ridges, under rectilinear tidal currents, increasing the critical bed shear stress for sand erosion decreases the growth rate and the wavelength of the preferred bedforms significantly, while the orientation angle slightly decreases. The dependence of the growth rate, wavelength and the orientation of the preferred bedforms on the tidal ellipticity is non-monotonic. A decrease in tidal frequency results in preferred bedforms with larger wavelength and smaller orientation angle, while their growth rate hardly changes. In the case of joint diurnal and semidiurnal tides, or spring-neap tides, the characteristics of the bedforms are determined by the dominant tidal constituent. For long bed waves, the number of anticyclonically/cyclonically oriented bedforms with respect to the principal

  16. Particle pressures in fluidized beds. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Campbell, C.S.; Rahman, K.; Jin, C.

    1996-09-01

    This project studies the particle pressure, which may be thought of as the force exerted by the particulate phase of a multiphase mixture, independently of that exerted by other phases. The project is divided into two parts, one concerning gas and the other liquid fluidized beds. Previous work on gas fluidized beds had suggested that the particle pressures are generated by bubbling action. Thus, for these gas fluidized bed studies, the particle pressure is measured around single bubbles generated in 2-D fluidized beds, using special probes developed especially for this purpose. Liquid beds are immune from bubbling and the particle pressures proved too small to measure directly. However, the major interest in particle pressures in liquid beds lies in their stabilizing effect that arises from the effective elasticity (the derivative of the particle pressure with respect to the void fraction), they impart to the bed. So rather than directly measure the particle pressure, the authors inferred the values of the elasticity from measurements of instability growth in liquid beds; the inference was made by first developing a generic stability model (one with all the normally modeled coefficients left undetermined) and then working backwards to determine the unknown coefficients, including the elasticity.

  17. Particle Pressures in Fluidized Beds. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Campbell, C.S.; Rahman, K.; Jin, C.

    1996-09-01

    This project studies the particle pressure, which may be thought of as the force exerted by the particulate phase of a multiphase mixture, independently of that exerted by other phases. The project is divided into two parts, one concerning gas and the other liquid fluidized beds. Previous work on gas fluidized beds had suggested that the particle pressures are generated by bubbling action. Thus, for these gas fluidized bed studies, the particle pressure is measured around single bubbles generated in 2-D fluidized beds, using special probes developed especially for this purpose. Liquid beds are immune from bubbling and the particle pressures proved too small to measure directly. However, the major interest in particle pressures in liquid beds lies in their stabilizing effect that arises from the effective elasticity (the derivative of the particle pressure with respect to the void fraction): they impart to the bed. So rather than directly measure the particle pressure, we inferred the values of the elasticity from measurements of instability growth in liquid beds the inference was made by first developing a generic stability model (one with all the normally modeled coefficients left undetermined)and then working backwards to determine the unknown coefficients, including the elasticity.

  18. Slope Morphology of Twin Peaks, Mars Pathfinder Landing Site

    Science.gov (United States)

    Hobbs, Steven; Paine, Colin; Clarke, Jon; Caprarelli, Graziella

    2010-05-01

    . This being the case, slope morphology results from shallow processes related to mass wasting and surface erosion, although it is obvious from the difference in slope angle between the upper and lower slopes that there is a difference either in lithology across the section of the hill, that the erosional effects were different, or that the surficial processes acting on the slopes were different. On Earth slopes frequently evolve by lower facets expanding upwards at the expense of the facet above, a process defined as slope retreat and replacement - lower slope facets replace upper slope facets. Therefore we conclude that the second possibility is more likely. The mid slope region marks a departure from symmetry with a 6˚ difference between the two sides. This may indicate separate processes operating on either side of the hill. Further investigation is currently underway to clarify the nature of the mid-hill slope differences. Additional studies are also being conducted to determine the sequence of lithologies forming the peak. References [1] Ahnert, F. (1970). Z. Geomorphol., Suppl Band 9, 88-101. [2] Kirkby, M.J. (1984). Z. Geomorphol 28(4), 405-426. [3] Young, A., (1972). Oliver and Boyd, Edinburgh. [4] Savigear, R.A.G. (1952). Trans. Inst. British Geog. 18, 31-51. [5] Pain, C.F. (1986). Catena 13, 227-239. [6] Gutierrez Elorza, M., and Sese Martinez, V.H., (2001). Geomorp.38, 19-29. [7] Montgomery, D.R. (2001). Am. J. of Sci. 301, 432-454. [8] Golombek, M. P., and N. T. Bridges (2000). J. Geophys. Res. 105(E1), 1841-1853. [9] Parker, T. J., and Rice Jr, J. W. (1997). J. Geophys. Res. 102(E11), 25,641-25,656. [10] Lucchitta, B. K., (1998) LPSC, XXIX.

  19. Landscape evolution in relation with occurrence of gravitational slope deformation and catastrophic landslides

    Science.gov (United States)

    Tsou, Ching-Ying; Chigira, Masahiro; Matsushi, Yuki; Chen, Su-Chin

    2013-04-01

    The Central Range of Taiwan is an example of a tectonically active orogen. The topography of a mountainous catchment of the Dahan River in northern side of the Central Range exhibits V-shaped inner valleys where landsliding is the dominant process of hillslope erosion and bedrock rivers are incising into the landscape. We take two approaches including (i) the study of present day morphostructural features of gravitationally deformed slopes and (ii) the study of the relationship between the gravitational slope deformation and fluvial incision to research the linkage of gravitational slope deformations, catastrophic landslides, and landscape evolution for the prediction of potential sites of future landslides. Mapped deep-seated gravitational slope deformations and scars of rainfall-induced rock/debris avalanches imply that their distributions are closely related to three series of convex slope breaks relating to the rejuvenation of topography by a three-phase fluvial incision leaded by three series of knickpoints migration. Many shallow rock/debris avalanches have occurred below the lowest slope break. By contrast, majority of gravitational slope deformations have occurred at the margins of the highest slope break around the paleosurface remnants, suggesting that the rejuvenation caused debuttressing of hillslopes and subsequent stress-release led to large scale slope destabilization, resulting in gravitational slope deformations. Catastrophic landslides in many locations deem to be preceded by gravitational slope deformation of rocks with adverse geological structures, many of which are buckling of alternating beds of sandstone and mudstone, and toppling of argillite and slate. The gravitationally deformed slopes change the topography and remain for a long time, and commonly accompany with some other types of mass movements (e.g. debris flows, rock/debris avalanches, and rockfalls). The results suggest that landslides are strongly controlled by geomorphology and

  20. Cofiring of difficult fuels: The effect of Ca-based sorbents on the gas chemistry in fluidised bed combustion; Kalsiumpohjaisten lisaeaineiden vaikutus leijukerrospolton kaasukemiaan vaikeiden polttoaineiden sekapoltossa

    Energy Technology Data Exchange (ETDEWEB)

    Aeijaelae, M.; Partanen, J.; Fabritius, M.; Elo, T.; Virta, A.K. [Imatran Voima Oy, Vantaa (Finland)

    1997-10-01

    The objective of this project is to establish the effects of Ca-based sorbents on sulphur, halogen and alkaline chemistry in fluidised bed combustion of difficult fuels, and to find out any restrictions on the use of these sorbents. The aim is to acquire sufficient knowledge to ensure the operational reliability of power plants and to minimise the emissions and costs of flue gas cleaning. The results enable the owner to anticipate necessary changes associated with slagging, fouling and emission control in the existing power plants, when there are plans to increase the range of fuels used. (orig.)

  1. Effect of Process and Post-Process Conditions on the Mechanical Properties of an A357 Alloy Produced via Laser Powder Bed Fusion

    Directory of Open Access Journals (Sweden)

    Alberta Aversa

    2017-02-01

    Full Text Available A357 samples were realized by laser powder bed fusion (LPBF on building platforms heated up to different temperatures. The effect of the preheating temperature and of the post processing heat treatment on the microstructure and the mechanical properties of the samples was studied. It was demonstrated that building platform heating can act as an in situ ageing heat treatment following the fast cooling that arises during laser scanning. A 17% higher ultimate tensile strength was achieved by the selection of the optimum building platform temperature. Moreover, the possibility to further increase the mechanical properties by means of a direct ageing heat treatment was investigated.

  2. Anisotropy of Soil Hydraulic Properties Along Arable Slopes

    Institute of Scientific and Technical Information of China (English)

    JING Yuan-Shu; ZHANG Bin; A.THIMM; H.ZEPP

    2008-01-01

    The spatial variations of the soil hydraulic properties were mainly considered in vertical direction.The objectives of this study were to measure water-retention curves,θ(ψ),and unsaturated hydraulic conductivity functions,K(ψ),of the soils sampled at different slope positions in three directions,namely,in vertical direction,along the slope and along the contour,and to determine the effects of sampling direction and slope position of two soil catenas.At the upper slope positions,the surface soils (0-10 cm) sampled in the vertical direction had a lower soil water content,θ,at a certain soil water potential (-1500 kPa <ψ<-10 kPa) and had the greatest unsaturated hydraulic conductivity,K,at ψ> -10kPa.At the lower slope positions,K at ψ>-10 kPa was smaller in the vertical direction than in the direction along the slope.The deep soils (100-110 cm) had similar soil hydraulic properties in all the three directions.The anisotropic variations of the hydraulic properties of the surface soils were ascribed to the effects of natural wetting and drying cycles on the structural heterogeneity.These results suggested that the anisotropy of soil hydraulic properties might be significant in influencing soil water movement along the slope and need to be considered in modeling.

  3. Fluidized bed calciner apparatus

    Science.gov (United States)

    Owen, Thomas J.; Klem, Jr., Michael J.; Cash, Robert J.

    1988-01-01

    An apparatus for remotely calcining a slurry or solution feed stream of toxic or hazardous material, such as ammonium diurante slurry or uranyl nitrate solution, is disclosed. The calcining apparatus includes a vertical substantially cylindrical inner shell disposed in a vertical substantially cylindrical outer shell, in which inner shell is disposed a fluidized bed comprising the feed stream material to be calcined and spherical beads to aid in heat transfer. Extending through the outer and inner shells is a feed nozzle for delivering feed material or a cleaning chemical to the beads. Disposed in and extending across the lower portion of the inner shell and upstream of the fluidized bed is a support member for supporting the fluidized bed, the support member having uniform slots for directing uniform gas flow to the fluidized bed from a fluidizing gas orifice disposed upstream of the support member. Disposed in the lower portion of the inner shell are a plurality of internal electric resistance heaters for heating the fluidized bed. Disposed circumferentially about the outside length of the inner shell are a plurality of external heaters for heating the inner shell thereby heating the fluidized bed. Further, connected to the internal and external heaters is a means for maintaining the fluidized bed temperature to within plus or minus approximately 25.degree. C. of a predetermined bed temperature. Disposed about the external heaters is the outer shell for providing radiative heat reflection back to the inner shell.