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Instrumentation for High-Performance Liquid Chromatography
Published in Grinberg Nelu, Rodriguez Sonia, Ewing’s Analytical Instrumentation Handbook, Fourth Edition, 2019
There are still two main means of solvent mixing employed by modern chromatographic instrumentation to provide the desired mobile phase composition: using low-pressure solvent proportioning (metering) valves before the pump or using one pump per solvent and varying the flow rates of the individual pumps. Low-pressure systems meter aliquots of individual solvent at the desired ratio before the intake of the pump. In high-pressure systems, each solvent is assigned to an individual pump, and the overall solvent composition of the mobile phase is controlled by the relative flow rates of the individual pumps. High-pressure pump mixing is thus limited by the resolution of the individual pump flows, whereas low-pressure mixing is limited to the resolution of the proportioning valve. Practically, low-pressure proportioning valves are limited to four solvents, and high-pressure mixing systems are limited to two solvents, leading to their designation as quaternary and binary systems. There are some key differences, which are summarized in Table 22.3.
Thermal treatment and sludge disposal
Published in Bhola R. Gurjar, Vinay Kumar Tyagi, Sludge Management, 2017
Bhola R. Gurjar, Vinay Kumar Tyagi
Gaseous discharge from a pelletizing drier used in the treatment of sewage sludge is partially directed back to a combustion chamber that generates an effluent, which is fed to the drier. Volumetric requirements of a gas scrubber and an after burner are reduced to the volume of gaseous discharge not recycled back to the combustion chamber. A concentrated stream of sewage sludge is mixed with a quantity of dehydrated particulate matter and supplied to a rotary pelletizing drier. Fuel and air undergo a combustion process and are mixed with additional air and part of the gaseous discharge in the combustion chamber, which generates a hot gaseous effluent that is directed through the drier. The effluent removes moisture from the mixture of concentrated sludge and dehydrated particulate sludge and the gaseous discharge. Entrained materials are initially separated from the gaseous discharge by cyclone separators. A gas flow-proportioning valve is disposed in a duct system interconnecting the cyclone separators, gas scrubber and combustion chamber for directing a portion of the gaseous discharge back to the combustion chamber.
Computer Simulation and Parameter Sensitivity Study of a Commercial Vehicle During Antiskid Braking
Published in H.-P. Willumeit, The Dynamics of Vehicles on roads and on tracks, 2018
The other brake-related items of interest in Table 3 are the effects of reduced rear brake effectiveness (Item 1.2) and load proportioning (Items 1.11, 1.12). Each of these influences are similar in effect and are advantageous for two reasons: (1) the reduced torque output of the rear brake, whether deriving from a reduction in brake effectiveness or the indicated proportioning valve mechanisms, results in improved brake torque distribution on the vehicle, thereby lessening the redistribution requirements performed by the antiskid system, and (2) the reduced rear torque raises the minimum brake pressures experienced during cycling, thereby reducing the influences of hysteresis and air supply time lags, as discussed above.
Examining the resiliency of intertwined supply networks: a jury-rigging perspective
Published in International Journal of Production Research, 2023
Javad Feizabadi, David M. Gligor, Thomas Y. Choi
The jury-rigging concept has components of search characteristic (i.e. rigging) and decision-making authority (i.e. jury) (Kauffman et al. 2018). The adaptive response in a supply network can be enacted by giving more autonomy and increasing the degrees of freedom among the firms for their potential response (Choi, Dooley, and Rungtusanatham 2001; Choi and Hong 2002; Levinthal and Marino 2015). An illustrative example of jury-rigging response occurred after a fire at a supplier working for Toyota. Aisin Seiki was the sole supplier of proportioning-valve for Toyota, famous for its low inventory level and higher vulnerability to production disruption (Kauffman et al. 2018). The disruption was avoided by the adaptive behaviors in the supply network in which other suppliers were able to learn promptly how to make the p-valve and supply it to Toyota. The interdependencies of other suppliers with Aisin Seiki in conjunction with delegated authority enabled them to circumvent the bureaucratic process of getting approvals and quickly alleviate the disruption. These collective behaviors to enhance the system’s adaptive capacity have been suggested in past research (Corning 2003; Kim, Chen, and Linderman 2015; Hajmohammad and Vachon 2016; Azadegan and Jayaram 2018).