291,500 research outputs found
CT Bed Bug Forum and additional information. Harvested on 2012: Dec. 7.
No full textBed bug information for recycling and refurbishing industries, shelters and other accommodations, schools and day care services.; Harvested from the web on 12/10/1
Effect of Distributed Superficial-Velocity in Deep-Bed Grain Drying
No full textThis paper deals with influence of velocity field distribution to heat and mass transfer process in deep bed grain dryers. Two-dimensional (2D) models of deep-bed grain dryers were built by considering simultaneously momentum, heat, and mass transfer in the drying air phase. The Navier-Stokes momentum equations are applied to simulate pressure drop and velocity field of the drying airflow. Effect of velocity distribution to the heat and mass transfer coefficient distribution were simulated along the height of grains bed. The dynamic equations are solved numerically by using finite difference method by utilization of alternating direction implicit method, while the momentum equations are solved numerically by utilization of SIMPLE algorithm. The simulation results showed that velocity distribution along the grains bed - 5 cm of bed height - did not so influenced to the heat and mass transfer coefficient. Further, the vector plot of drying air superficial velocity field and contour of pressure distribution along deep bed of grain was simulated
The influence of multiple tubes on the tube-to-bed heat transfer in a fluidised bed
No full textThere have been few studies modelling both flow and heat transfer in fluidised beds. The kinetic theory of granular flow (KTGF) has been used for flow prediction in the past without heat transfer modelling. In the present study, a two-fluid Eulerian-Eulerian formulation incorporating the KTGF was applied first to a tube-to-bed reactor with one immersed tube and compared with the results in the literature. The bed was then modified to introduce two and three heated tubes. The effects on the flow and temperature distribution, local heat transfer coefficients and averaged heat transfer coefficients over a 3.0s time period were carried out. Results showed that increasing the number of tubes promotes heat transfer from tubes to the particles and flow. The heat transfer coefficients extracted from the single-tube to three-tube cases were analyzed in detail, confirming the importance of linking flow/particle and heat transfer calculation
Changes in intervertebral disc morphology persist 5 mo after 21-day bed rest
No full textAs part of the nutrition-
countermeasures (NUC) study in Cologne, Germany in 2010,
seven healthy male subjects underwent 21 days of head-down tilt bed
rest and returned 153 days later to undergo a second bout of 21-day
bed rest. As part of this model, we aimed to examine the recovery of
the lumbar intervertebral discs and muscle cross-sectional area (CSA)
after bed rest using magnetic resonance imaging and conduct a pilot
study on the effects of bed rest in lumbar muscle activation, as
measured by signal intensity changes in T2-weighted images after a
standardized isometric spinal extension loading task. The changes in
intervertebral disc volume, anterior and posterior disc height, and
intervertebral length seen after bed rest did not return to prebed-rest
values 153 days later. While recovery of muscle CSA occurred after
bed rest, increases (P 0.016) in multifidus, psoas, and quadratus
lumborum muscle CSA were seen 153 days after bed rest. A trend was
seen for greater activation of the erector spinae and multifidus muscles
in the standardized loading task after bed rest. Greater reductions of
multifidus and psoas CSA muscle and greater increases in multifidus
signal intensity with loading were associated with incidence of low
back pain in the first 28 days after bed rest (P 0.044). The current
study contributes to our understanding of the recovery of the lumbar
spine after 21-day bed rest, and the main finding was that a decrease
in spinal extensor muscle CSA recovers within 5 mo after bed rest but
that changes in the intervertebral discs persist
Hydrodynamic Characteristics of a Fluidized Bed with Rotating Distributor
No full textThe performance of a novel rotating distributor fluidized bed is presented.
The pressure drop and the standard deviation of pressure fluctuations were used to find the minimum fluidization velocity, Umf, and to characterize
the quality of fluidization at different rotational speeds of the distributor
plate. Experiments were conducted in the freely bubbling regime in a 0.19 m
i.d. fluidized bed, operating with Group B particles according to Geldart’s
classification. A decrease in Umf is observed when the rotational speed increases.
Frequency analysis of pressure fluctuations shows that fluidization
can be controlled by the adjustable rotational speed, at several excess gas
velocities
Numerical analysis of flow structures and bed entrainment in turbulent open-channel flow
No full textPhDThe results from a Direct Numerical Simulation (DNS) and a Large Eddy
Simulation (LES) are employed to study the large-scale coherent structures
and bed entrainment in the turbulent open-channel flow. The gravel bed is
represented by a hexagonal arrangement of uniform spheres.
The large-scale coherent structures are composed of a group of quasistreamwise
vortices and asymmetric hairpin vortices. The meandering
structures are shown to be longer than the length of the computational box,
more than 20 times the effective flow depth in this study, and the width
tends to be one order of magnitude smaller than the length. The signature
of the large-scale motion is elongated local maximum of streamwise
velocity. It is also found that these structures contribute substantially to
both of the Reynolds Stress (RS) and the Turbulent Kinetic Energy (TKE).
The entrainment of bed gravels is investigated by the three-dimensional
analysis of the relationship between near-wall coherent structures and the
force moments exerted on the particles. It is found that the spanwise drag
moment (MD2) is of the same order of magnitude compared with the
streamwise drag moment (MD1). The majority of MD2 originates from
pressure whilst the viscous force plays as an important role as pressure for
MD1. The contributions of the forces at different heights of the particle to
MD1 and MD2 are explored. The quasi-streamwise vortices are strongly
associated with MD2 and the ejections are shown to be more favorable for
bed entrainment than the sweeps in this bed condition
Silicon Chemical Vapor Deposition on macro and submicron powders in a fluidized bed
No full textTitanium oxide (TiO2) submicron powders have been treated by Chemical Vapor Deposition (CVD) in a vibro-fluidized bed in order to deposit silicon layers of nanometer scale on each individual grain from silane (SiH4). Experimental results show that for the conditions tested, the original granular structure of the powders is preserved for 90% of the initial bed weight while the remaining 10% consists of agglomerates in millimetre range found near the distributor of the reactor. A comparison between experimental and modelling results using the MFIX code shows that for Geldart's Group B alumina particles (Al2O3), the model represents both the bed hydrodynamics and silane conversion rates quite well. The future objective is to extend the simulation capability to cohesive submicron powders in order to achieve better predictability of the phenomena governing ultrafine particles
Changes in lower extremity muscle function after 56 days of bed rest
No full textPreservation of muscle function, known to decline in microgravity and simulation (bed rest), is important for successful spaceflight missions. Hence, there is great interest in developing interventions to prevent musclefunction
loss. In this study, 20 males underwent 56 days of bed rest.
Ten volunteers were randomized to do resistive vibration exercise (RVE). The other 10 served as controls. RVE consisted of muscle contractions against resistance and concurrent whole-body vibration.
Main outcome parameters were maximal isometric plantar-flexion force (IPFF), electromyography (EMG)/force ratio, as well as jumping power and height. Measurements were obtained before and after bed rest, including a morning and evening assessment on the first day of recovery from bed rest. IPFF (-17.1%), jumping peak power (-24.1%), and height (-28.5%) declined (P < 0.05) in the control
group. There was a trend to EMG/force ratio decrease (-20%; P < 0.051). RVE preserved IPFF and mitigated the decline of countermovement jump performance (peak power -12.2%; height -14.2%). In both groups, IPFF was reduced between the two measurements of the first day of reambulation. This study indicates that bed rest and countermeasure exercises differentially affect the various functions of skeletal muscle. Moreover, the time course during recovery needs to
be considered more thoroughly in future studies, as IPFF declined not only with bed rest but also within the first day of reambulation. RVE was effective in maintaining IPFF but only mitigated the decline in jumping performance. More research is needed to develop countermeasures that maintain muscle strength as well as other muscle functions including power
Method for Particle Size Control During the Drying and Granulation in Fluidized Bed
No full textThe fluidized bed process presented in this paper is suitable for recovery of solids from
solutions in the form of granules. The solution is sprayed into the bed and as solvent
evaporates, solid material is deposited on the surface of fluidizing particles. During this
process, particle growth takes place by surface layering and/or agglomeration. A special
grinder is used in the fluidized bed to control particle growth by causing selective
disintegration of large particles. For steady state operation, the most important task is to
determine the existing particle size distribution in the fluidized bed. A special method
was developed to measure torque and stress fluctuations* in the bed of particles. Using a
correlation between torque and stress fluctuations and particle size, this method and
device can be used for direct control of the rotation speed of the grinder to produce
granules of given size in the fluidized bed. Results of torque and stress measurements
and their correlation to particle size are presented
The effects of bed rest and countermeasure exercise on the endocrine system in male adults: Evidence for immobilization-induced reduction in sex hormone-binding globulin levels
No full textBackground and Aim. There is limited data on the effects of inactivity (prolonged bed-rest) on parameters of endocrine and metabolic function; we therefore aimed to examine changes in these systems during and after prolonged (56-day) bed-rest in male adults.
Subjects and Methods. 20 healthy male subjects underwent 8 weeks of strict bed-rest and 12 months follow-up as part of the Berlin Bed-Rest Study. Subjects were randomised to an inactive group or a group that performed resistive vibration exercise (RVE) during bed-rest. All outcome parameters were measured before, during and after bed-rest. These included body composition (by whole body dual X-ray absorptiometry), sex hormone-binding globulin (SHBG), testosterone (T), estradiol (E2), prolactin (PRL), cortisol (C), thyroid stimulating hormone (TSH) and free triiodothyronine (FT3).
Results. Serum SHBG levels decreased in inactive subjects but remained unchanged in the RVE group (p<.001). Serum T concentrations increased during the first 3-weeks of bed-rest in both groups (p<.0001), while E2 levels sharply rose with re-mobilisation (p<.0001). Serum PRL decreased in the CTRL group but increased in the RVE group (p=.021). C levels did not change over time (p≥.10). TSH increased whilst FT3 decreased during bed-rest (p all≤.0013).
Conclusions. Prolonged bed-rest has significant effects on parameters of endocrine and metabolic function, some of which are related to, or counteracted by physical activity
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