Home  About us  Contact
 

Proper Operation (proper + operation)

Distribution by Scientific Domains
Chemistry40%

Selected Abstracts

Is ileoanal the proper operation for indeterminate colitis: The case against

INFLAMMATORY BOWEL DISEASES, Issue 5 2002
Dr. David J. Schoetz Jr.
No abstract is available for this article. [source]

Fabrication of Precise Fluidic Structures in LTCC

INTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY, Issue 1 2009
Fred Barlow
A number of emerging applications of low-temperature co-fired ceramic (LTCC) require embedded fluidic structure within the co-fired ceramic and or precise external dimensional tolerances. These structures enable the control of fluids for cooling, sensing, and biomedical applications, and variations in their geometry from the design can have a significant impact on the overall performance of the devices. One example of this type of application is a multilayer cooler developed recently by the authors for cooling laser diode bars. In many laser systems, laser diodes are the primary emitters, or assemblies of these diode bars are used to pump traditional laser crystals such as Nd:YLF. Assemblies of these diodes require large amounts of electrical current for proper operation, and the device operating temperature must be carefully controlled in order to avoid a shift in the output wavelength. These diodes are packaged into water-cooled assemblies and by their nature dissipate enormous amounts of heat, with waste heat fluxes on the order of 2000 W/cm2. The traditional solution to this problem has been the development of copper multilayer coolers. Assemblies of laser diodes are then formed by stacking these diode bars and coolers. Several problems exist with this approach including the erosion of the copper coolers by the coolant, a requirement for the use of deionized water within the system, and a significant CTE mismatch between the diode bar and the metal cooler. Diodes are bonded to these metal structures and liquid coolant is circulated through the metal layers in order to cool the diode bar. In contrast, the coolers developed by the authors utilize fluid channels and jets formed within LTCC as well as embedded cavity structures to control the flow of a high-velocity liquid and actively cool the laser diode bars mounted on the surface of the LTCC., The dimensional tolerances of these cooler assemblies and complex shapes that are used to control the fluid can have a significant impact on the overall performance of the laser system. This paper describes the fabrication process used to create the precise channel and jet structures used in these LTCC-based coolers, as well as some of the challenges associated with these processes. [source]

Prediction, potential and control of plume from wet cooling tower of commercial buildings in Hong Kong: A case study

INTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 8 2007
S. K. Tyagi
Abstract This paper presents a case study of the prediction, potential and control of plume in wet cooling towers from a huge commercial building in Hong Kong based on the weather data available for a particular year. The power input is found to be lower and the coefficient of performance (COP) moderate when all the 10 towers with low speed are in use, while it is found to be reverse when there are five towers, especially, three low and two high-speed towers are used. It is also found that the combined heating and cooling option can be a better approach than that of the heating option alone from the point of view of thermodynamics as well as from the point of view of economics. The COP of the chillers increases from 6.01 to 7.09 when the number of cooling towers increases from five to ten. On the other hand, the power consumption first decreases and then increases which is mainly due to the increment in the consumption of fan power from 270 to 900 kW for both options. The overall power consumption decreases slightly for the combined heating and cooling option, while in the heating option, the overall power consumption increases slightly. However, it is observed that a proper operation of cooling towers is an effective means to control and/or at least reduce the potential of visible plume generated by wet cooling towers at the existing chilling plant design for this particular building. Copyright © 2006 John Wiley & Sons, Ltd. [source]

Polarization-dependent six-beam X-ray pinhole topographs

ACTA CRYSTALLOGRAPHICA SECTION A, Issue 4 2006
Kouhei Okitsu
X-ray six-beam pinhole topograph images were obtained for a silicon crystal with incident synchrotron X-rays. The polarization state of X-rays incident on the sample crystal was controlled by using a four-quadrant phase-retarder system [Okitsu et al. (2002). Acta Cryst. A58, 146,154] that can be rotated around the transmitted beam axis to generate arbitrarily polarized X-rays. Quantitative agreement was found between the experimental and computer-simulated topograph images based on the n -beam Takagi,Taupin dynamical theory under the assumption that the polarization state of the incident X-rays was identical with the experiment. This result confirmed the validity of the computer algorithm to solve the n -beam dynamical theory and the proper operation of the rotating four-quadrant phase-retarder system simultaneously. [source]

Design of Simulated Moving Bed Plants by Using Noncompetitive Langmuir Isotherms

CHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 10 2009
M. Fütterer
Abstract The simulated moving bed process is increasingly used for the separation of binary mixtures. To ensure proper operation, the volumetric flow rates and the time interval must be exactly adjusted. This study presents a general method for determining the control variables for a dispersion-free SMB process. For noncompetitive Langmuir isotherms, explicit equations are derived for the case of complete separation. The proposed method allows both a good estimation of the time trajectories of the concentrations at the drains and the design of new applications for optimization and control of SMB plants. [source]