208,484 research outputs found
Combined effect of electric field and surface modification on pool boiling of R-123
No full textThis thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.The effect of surface modification and high intensity electric field (uniform and non – uniform) acting separately or in combination on pool boiling of R-123 is presented in this thesis. The effect of surface modification was investigated on saturated pool boiling of R-123 for five horizontal copper surfaces modified by different treatments, namely: an emery polished surface, a fine sandblasted surface, a rough sandblasted surface, an electron beam (EB) enhanced surface and a sintered surface. Each 40 mm diameter heating surface formed the upper face of an oxygen-free copper block, electrically heated by embedded cartridge heaters. The experiments were performed from the convective heat transfer regime to the critical heat flux, with both increasing and decreasing heat flux, at 1.01 bar, and additionally at 2 bar and 4 bar for the emery polished surface. Significant enhancement of heat transfer with increasing surface modification was demonstrated, particularly for the EB enhanced and sintered surfaces. The emery polished and sandblasted surface results are compared with nucleate boiling correlations and other published data. The effect of uniform and non-uniform electric fields on saturated pool boiling of R-123 at 1.01 bar pressure was also examined. This method of heat transfer enhancement is known as electrohydrodynamic abbreviated as EHD-enhancement. A high voltage potential was applied at the electrode located above the heating surface, which was earthed. The voltage was varied from 0 to 30 kV. The uniform electric field was provided through a 40 mm diameter circular electrode of stainless steel 304 wire mesh having an aperture of 5.1 mm, while the non-uniform electric field was obtained by using a 40 mm diameter circular rod electrode with rods 5 and 8 mm apart. The effect of uniform electric field was investigated using all five modified surfaces, i.e. emery polished, fine sandblasted, rough sandblasted, EB enhanced and sintered surfaces, while non – uniform electric field was tested using the emery polished, fine sandblasted, EB enhanced and sintered surfaces. The effect of pressure on EHD enhancement was also examined using emery polished surface at saturation pressure of 2 and 4 bars while the electric field was fix at 20 kV corresponding to 2 MV/m. Further, the bubble dynamics is presented for the emery polished surface obtained using a high-speed high – resolution camera.The Government of Pakista
ENGAGE Biocrates GWA meta analyses - data
No full textThese files contain the summary statistics of the meta analyses performed in Draisma, H., Pool, R., Kobl, M. et al. Genome-wide association study identifies novel genetic variants contributing to variation in blood metabolite levels. Nat Commun 6, 7208 (2015) (https://doi.org/10.1038/ncomms8208)
Compound effect of EHD and surface roughness in pool boiling and CHF with R-123
No full textThis article is a post-print version of the fianl published article which may be accessed at the link below.Saturated pool boiling of R-123 at 1 bar, including the critical heat flux (CHF), was enhanced by modifying the surface characteristics and applying a high intensity electrostatic field, the latter termed electrohydrodynamic (and abbreviated EHD) enhancement. The heat flux was varied from very low values in the natural convection regime up to CHF. Experiments were performed with increasing and decreasing heat flux to study boiling hysteresis without and with EHD. Boiling occurred on the sand blasted surface of a
cylindrical copper block with embedded electrical heating elements, with standardized surface parameter Pa = 3.5 μm. The electric field was generated by a potential of 5 kV to 25 kV, applied through a 40 mm diameter circular electrode of ss-304 wire mesh, aperture size 5.1 mm, located at distances of 5 - 60 mm from the surface, with most of the data obtained for 20 mm. The data for the rough surface were compared with earlier data for a smooth surface and indicated a significant increase in the heat transfer rates. EHD produced a further increase in the heat transfer rates, particularly at low heat flux values and near the CHF. Boiling hysteresis was reduced progressively by EHD and eliminated at high field strength.This work was supported by Government of Pakistan under a scholarship programme
Understanding pool-riffle dynamics through continuous morphological simulations
No full textPool-riffle dynamics is governed by complex time and spatial interactions between water and sediment flows. In the last few decades, significant advances have been made in characterizing and modeling the hydrodynamics of pool-riffle sequences, and this information has been extensively used as the basis of conceptual models to describe or infer pool-riffle morphodynamics. A lot less attention, however, has been paid to the coupled dynamics of flow and sediment, which is essential to fully understand these complex geomorphic systems. This paper uses an unsteady 1-D flow-morphology and bed-sorting model to analyze pool-riffle dynamics. The model is first applied to a pool-riffle sequence on a 1.1 km reach of the lower Bear Creek, Arkansas, United States. After showing the model's ability to describe the general reach hydrodynamics and morphological evolution over 1 year, the detailed sediment and flow information is used to investigate pool-riffle dynamics in terms of self-maintenance mechanisms. Two effects that have been only marginally explored in the past, i.e., bed sediment sorting and downstream riffle control, are explained and quantified with the help of the model's outputs. The results show that self-maintenance occurs more frequently than previously thought as a result of grain sorting and that erosion or deposition of contiguous riffles also constitutes a self-maintenance mechanism. These findings provide the support for a physically based, integral description of pool-riffle morphodynamics and highlight the importance of flow and sediment variability on pool-riffle self-maintenance. The morphodynamic analysis bridges the gap between observations and current theories based mainly on hydrodynamic information
[Texas Historical Commission Marker: Pool Manufacturing Company]
No full textPhotograph of the Texas Historical Commission marker for Pool Manufacturing Company in Sherman, Texas. Text: BACK
Originally chartered September 20, 1909, as Sherman Overall Manufacturing. First machinery was secured from a glove manufacturer and placed in the Birge-Forbes Building on East Lamar Street.
Company was purchased in August 1911, by R. F. Pool and son Carl; in following years, expansion led to use of several separate buildings in downtown Sherman. Name changed to Pool Manufacturing Co. in 1925.
In December 1928, plant was moved to this site with 60,000 square feet of manufacturing space.
Originally manufacturing overalls, they later added work pants, work shirts, and matched uniforms; all bearing the Pool's "Swetpruf" brand, an important first in the industry being a colorfast khaki. Pool was leader in the practice of preshrinking fabrics before manufacture; this was before sanforization.
In the early 1930s Pool introduced the original Army cramerton cloth, basic fabric still used by the U. S. Armed Forces. Carl Pool began and developed application of modern-day industrial engineering to manufacture of garments. Further expansion recently has put Pool into the field of manufacturing sports clothes.
Market area now extends to the Pacific Coast and some foreign countries
An Intergenerational Common Pool Resource Experiment
No full textintergenerational common pool resources;growth and altruism;free-riding intentions
Member Commitment and the Market and Financial Performance of the Saskatchewan Wheat Pool
No full textSince 2001 several of the largest agricultural co-operatives in Western Canada and the United States have battled impending bankruptcy or ceased operations. In February 2001 Dairyworld Foods was bought out by Montreal dairy processor and cheese producer Saputo Inc. (Saputo; Toronto Stock Exchange). In November 2001, Agricore, formed through a 1998 merger of Alberta Wheat Pool Ltd. and Manitoba Pool Elevators, merged with United Grain Growers to form Agricore United (Agricore United). In the United States, AgWay and Farmland Industries filed for Chapter 11 bankruptcy protection in 2002 (Reuters, 2000), while the Saskatchewan Wheat Pool (hereinafter referred to as SWP or the Pool) underwent a massive debt restructuring in 2003 after four years of consecutive multi-million dollar net losses (SWP Annual Report, 2003). This decline in the market and financial performance of agricultural co-operatives has been associated with a decline in the commitment of the members to their co-operatives (Fulton, 1999; Fulton and Giannakas, 2001; Richards, Klein and Walburger, 1998; Burt and Wirth, 1990). The purpose of this article is to examine the market and financial performance of one of a number of co-operatives that have faced recent financial and market hardships, and to link this performance to member commitment. Specifically, the article examines whether the Pool’s declining market and financial performance is consistent with the predictions that emerge from a model that examines the impact of falling member commitment in a co-operative.Marketing,
Effect of torch angle on arc properties and weld pool shape in stationary GTAW
No full textIn this paper, a three dimensional numerical simulation is performed on a stationary arc to study the effect of torch angle in gas tungsten arc welding (GTAW) of SS304 stainless steel. A comparison has been made to investigate 90o and 70o torch angles and analyze the effect on arc and weld pool shape. Current density, heat flux and gas shear stress are calculated in the arc region and are used as input to the workpiece to determine the weld pool. Buoyancy and Marangoni shear also affect the weld pool shape and are taken into account. The computed and experimental results are observed symmetric for 90o torch angle. For 70o torch angle, current density and hence the heat flux due to electron contribution is found the maximum behind and heat flux due to conduction and convection is found the maximum ahead of the electrode tip in the welding direction. This makes the maximum of total heat flux symmetric along the arc center. Heat flux due to conduction and convection decreases as the torch angle decreases resulting in a shallow weld pool. The nonsymmetric “w” shaped weld pool is developed by the combined effect of the gas shear and Marangoni convection. It is found that for 70o torch angle, the weld pool becomes non-symmetric, shallow and wide ahead of the electrode tip in the welding direction. The numerical weld pool shapes are verified through experiments
Melt Pool and Keyhole Behavior Analysis for Deep Penetration Laser Welding
No full textOne usually defines the main characteristic of the welding performances of a given laser system by its “penetration curve” that corresponds to the welding depth as a function of the welding speed Vw for a given set of operating parameters. Analysis of a penetration curve is interesting and gives very fruitful results. Coupled with high speed video imaging of melt pool surface and ejected plume behaviors, the analysis of this penetration curve on a very large range of welding speeds, typically from 0 to 50 m/min, has allowed us to observe very different and characteristic regimes. These regimes are mainly characterized by the physical processes by which they impede the laser beam penetration inside the material. We show that it is only at rather high welding speeds that these limiting processes are reduced. Consequently the scaling law of welding depth with welding speed is in agreement with adapted modeling of this process. On the other hand, as the welding speed is reduced, different effects depending of the weld pool dynamics and plume interaction, strongly disturb the keyhole stability and are responsible of the deviation of the penetration curve from the previous modeling that agrees with a 1/Vw scaling law. A corresponding criterion for the occurrence of this effect is defined
Letter from William R. Hughes, Petersburg, Virginia, to Sergeant Wilson P. Pool, August 16, 1864
No full textWilliam R. Hughes writes this letter while serving in the 41st Alabama Infantry during the Civil War. It is from a collection of letters that he has written from bivouacs in Tennessee, Mississippi, and Virginia, 1862-1864, primarily to his wife in Northport, Alabama, but also to his mother and other family members. The letters include news of family and friends, accounts of camp life, and other matters
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