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The performance of a pilot-scale, struvite crystallization process, for recovering phosphorus from various supernatants, was investigated. Using synthetic supernatant, as well as anaerobic digester supernatants from two full-scale...
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The performance of a pilot-scale, struvite crystallization process, for recovering phosphorus from various supernatants, was investigated. Using synthetic supernatant, as well as anaerobic digester supernatants from two full-scale wastewater treatment plants located in Vancouver, B.C., Canada, it was found that over 90% phosphate removal efficiency was achieved through controlling the supersaturation ratio, operational pH and magnesium dosage in the supernatant. With a high supersaturation ratio, or high operational pH, or high magnesium dosage, excellent phosphate removal was achieved. However, an operational pH greater than 8 was not necessary; it was possible to control the process using a high magnesium dosage in place of a higher operating pH, but without a compromise in phosphate removal. Chemical analysis of the harvested crystals indicated very pure struvite (in excess of 91%), with only small amounts of residual calcium, carbonate, and trace metals. Most crystals exceeded 2mm in mean diameter.Le rendement d'un processus de cristallisation de la struvite à l'échelle pilote pour l'enlèvement du phosphore de divers surnageants a été étudié. L'essai utilisant un surnageant synthétique ainsi que des surnageants d'un digesteur anaérobie provenant de deux usines de traitement des eaux usées pleine grandeur à Vancouver, C.-B., Canada, a révélé que plus de 90 % de l'efficacité de la déphosphatation était due au contrôle du degré de sursaturation, du pH de fonctionnement et du dosage de magnésium dans le surnageant. Une excellente déphosphatation a été réalisée à un haut degré de sursaturation ou à un fort pH de fonctionnement ou encore à un dosage élevé de magnésium. Toutefois, un pH de fonctionnement supérieur à 8 n'était pas nécessaire; il a été possible de contrôler le processus en utilisant un dosage élevé de magnésium au lieu d'un fort pH de fonctionnement, mais sans influencer la déphosphatation. L'analyse chimique des cristaux récoltés a indiqué de la struvite très pure (plus de 91 %) et une petite quantité de calcium, de carbonate et de métaux traces résiduels. Le diamètre de la plupart des cristaux est supérieur à 2mm.
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We consider the scattering of plane acoustic waves by spherical objects near a plane hard surface. The angles of incidence are arbitrary and so are the distances of the objects from the hard boundary. We use the method of images. ...
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We consider the scattering of plane acoustic waves by spherical objects near a plane hard surface. The angles of incidence are arbitrary and so are the distances of the objects from the hard boundary. We use the method of images. The final result for the sound field consists of four parts: the incident field and its reflection from the boundary, which are shown combined; the scattered field from the sphere, and that scattered by its image. These last two appear coupled since both sphere and image are repeatedly interacting with each other. The entire solution is referred to the center of the real sphere. This can be accomplished in an exact fashion by means of the addition theorems for spherical wave-functions. These theorems are taken from the atomic physics literature, where they are more frequently used. The required coupling coefficients, b/sub mn/, are obtained from the solution of an infinite linear complex system of transcendental equations with coefficients given by series. The system is suitably truncated to obtain numerical predictions for the form-functions by means of the Gauss-Seidel iteration method. Many calculations are displayed exhibiting the distortion that the proximity of the hard boundary causes on the free-space solution. The form-functions are graphed versus ka, for various values of the normalized separation D/spl equiv/d/a of the sphere from its image. They are also plotted versus the angle of observation, for fixed values of /spl Omega/=La and D. These plots are the exact benchmark curves against which the accuracy of approximate solutions, found by other methods, could be assessed. They could also serve to determine the distances above the bottom, beyond which the bottom effect could be neglected. This is an idealized model to predict the distorted sonar cross section of a hard spherical object near a hard flat bottom.
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The functional, flowline and cellular layouts are traditional facility layouts that have been discussed extensively in the literature. However, due to the large variety of parts usually produced in jobshops, none of these layouts ...
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The functional, flowline and cellular layouts are traditional facility layouts that have been discussed extensively in the literature. However, due to the large variety of parts usually produced in jobshops, none of these layouts by themselves provide a satisfactory layout solution. This paper introduces a new idea in layout design that decomposes a layout into a network of "layout modules." Each module has a unique material-flow pattern, which, in some cases, corresponds to that of one of the traditional layouts. The use of layout modules allows for a single facility to have different types of layout configurations designed for different portions of its material-flow network. This paper introduces a systematic method for implementation of this design approach and demonstrates its application using a sample of routings obtained from industry.
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The introduction of a 36V battery along side of the 12V battery will enhance starting reliability, but it also creates new risks and, therefore, a strategy for jump start is needed. This paper discusses the issues that must be add...
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The introduction of a 36V battery along side of the 12V battery will enhance starting reliability, but it also creates new risks and, therefore, a strategy for jump start is needed. This paper discusses the issues that must be addressed with respect to charging and jump starting the batteries in the 42V/14V dual voltage systems.
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This paper demonstrates the identification of crack depths using signals obtained from eddy current testing (ECT). The identification method is based on finite elements with the pre-computed unflawed database approach and a meshle...
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This paper demonstrates the identification of crack depths using signals obtained from eddy current testing (ECT). The identification method is based on finite elements with the pre-computed unflawed database approach and a meshless crack representation technique, and parameter estimation in nonlinear problems. Four different cracks are estimated by using laboratory data.
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To study equilibrium temporal dynamics and the mechanisms of magnetohydrodynamic instabilities, a 16-channel heterodyne electron cyclotron emission (ECE) radiometer has been developed to view the J-TEXT tokamak from the low field ...
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To study equilibrium temporal dynamics and the mechanisms of magnetohydrodynamic instabilities, a 16-channel heterodyne electron cyclotron emission (ECE) radiometer has been developed to view the J-TEXT tokamak from the low field side. The ECE radiometer detects second-harmonic extraordinary mode in the frequency band of 94–125 GHz which corresponds to resonances from 1.8 T to 2.2 T. This ECE system consists of an ECE transmission line, a radio frequency unit, and two 8-channel intermediate frequency units. An in situ blackbody calibration source is applied for system calibration by comparison of hot and cold sources in order to provide an absolute temperature measurement.
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A transmission-line model for thin-film heads is presented in which the magnetic structure is divided into four sections. In one of them, the width decreases at a constant rate; in another, the spacing between the magnetic layers ...
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A transmission-line model for thin-film heads is presented in which the magnetic structure is divided into four sections. In one of them, the width decreases at a constant rate; in another, the spacing between the magnetic layers behaves in a similar way. The appropriate differential equations are solved and the boundary conditions are satisfied. Frequency effects are incorporated by way of complex effective permeabilities. Edge effects are taken into account. The computed impedance functions agree well with experiment.
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