REDUCTION OF SPATIAL TEMPERATURE VARIATIONS IN AIR-COOLED STORAGE ROOMS. II.

1946 ◽  
Vol 24f (5) ◽  
pp. 380-395
Author(s):  
J. W. Hopkins ◽  
T. A. Steeves ◽  
W. H. Cook
Keyword(s):  
Vertical Distribution ◽  
Heat Load ◽  
Air Flow ◽  
Temperature Gradients ◽  
Single Factor ◽  
Temperature Variations ◽  
Storage Room ◽  
End To End ◽  
Practical Implications ◽  
Spatial Temperature

Measurements made under a series of imposed conditions of heat load, dunnage spacing, and air flow were in agreement with previous work in this laboratory in demonstrating (a) the occurrence of appreciable permanent temperature gradients in material, whether exothermic or not, stacked in an air-cooled storage room, and (b) the possibility of markedly reducing these gradients by effective channelling of air through the stack. With end-to-end circulation, blocking of voids in the room was the most important single factor in minimizing intra-stack temperature differentials under the conditions of these tests. Further improvement was effected by the provision of optimum dunnage and by augmenting the air flow. It is to be inferred that with blocked voids, dunnage should be extended to all external surfaces of the stack. The desirability of uniform transverse and vertical distribution of the circulating air was also evident. Further trials on a larger scale are required to explore the practical implications of these findings.

A FLUID SYSTEM FOR TRANSFERRING HEAT OVER SMALL TEMPERATURE GRADIENTS WITHOUT FORCED CIRCULATION

1940 ◽  
Vol 18a (8) ◽  
pp. 144-150
Author(s):  
W. H. Cook ◽  
T. A. Steeves
Keyword(s):  
Liquid Ammonia ◽  
Temperature Gradients ◽  
Fluid System ◽  
Small Temperature ◽  
Thermostatic Control ◽  
Forced Circulation ◽  
Temperature Variations ◽  
Spatial Temperature

An enclosed system of piping partly filled with liquid ammonia was found to transfer useful quantities of heat to a bunker containing a solid refrigerant (ice), with temperature gradients of 30 to 50° F. without the use of forced circulation. The system could be adapted to reduce spatial temperature variations and provide thermostatic control where solid refrigerants are used, as in railway refrigerator cars. Such arrangements are discussed briefly.

The Effect of Money Denomination on Prosocial Behavior: Through the Perspective of Metaphorical Cognitive Theory

2021 ◽  
pp. 003329412110070
Author(s):  
Jianfeng Yang ◽  
Tao Xu ◽  
Yanhui Hou ◽  
Emily C. Monczynski ◽  
Xiaochuan Jiang
Keyword(s):  
Prosocial Behavior ◽  
Sample Size ◽  
Alternative Explanation ◽  
Cognitive Theory ◽  
Design Experiment ◽  
Single Factor ◽  
Behavior Study ◽  
Factor Design ◽  
Factorial Design Experiment ◽  
Practical Implications

Based on metaphorical cognitive theory, this research did four experiments to examine whether and how one important feature of money, denomination, could influence prosocial behavior. Study 1 was an experiment with a sample size of 209 undergraduates ( Mage = 18.97) showed that a larger denomination enhanced the probability of participants engaging in prosocial behavior rather than with a smaller denomination. Study 2 collecting data from 269 undergraduates ( Mage = 18.50) further showed that larger denominations condition inspired more prosocial behavior than the control condition; and the small denominations condition produced similar levels of prosocial behavior to the control condition. Study 3 used single factor design with a sample size of 192 undergraduates ( Mage = 20.49) repeated the results of Study 2. Furthermore, Study 3 excluded an important alternative explanation that the value rather than the denomination influenced prosocial behavior. Last, Study 4 applied a factorial design experiment with a sample size of 132 undergraduates ( Mage = 20.92) which demonstrated that generosity mediated the effect of denomination on prosocial behavior; the effect of denomination on prosocial behavior did not depend on money priming methods. Finally, theoretical and practical implications were discussed.

scholarly journals Cardiac Spiral Wave Drifting Due to Spatial Temperature Gradients – a Numerical Study

2018 ◽  
Author(s):  
Guy Malki ◽  
Sharon Zlochiver
Keyword(s):  
Numerical Simulations ◽  
Single Cell ◽  
Numerical Study ◽  
Spiral Wave ◽  
Spiral Waves ◽  
Temperature Gradients ◽  
Effect Of Temperature ◽  
Local Perturbation ◽  
Marginal Effect ◽  
Spatial Temperature

ABSTRACTCardiac rotors are believed to be a major driver source of persistent atrial fibrillation (AF), and their spatiotemporal characterization is essential for successful ablation procedures. However, electrograms guided ablation have not been proven to have benefit over empirical ablation thus far, and there is a strong need of improving the localization of cardiac arrhythmogenic targets for ablation. A new approach for characterize rotors is proposed that is based on induced spatial temperature gradients (STGs), and investigated by theoretical study using numerical simulations. We hypothesize that such gradients will cause rotor drifting due to induced spatial heterogeneity in excitability, so that rotors could be driven towards the ablating probe. Numerical simulations were conducted in single cell and 2D atrial models using AF remodeled kinetics. STGs were applied either linearly on the entire tissue or as a small local perturbation, and the major ion channel rate constants were adjusted following Arrhenius equation. In the AF-remodeled single cell, recovery time increased exponentially with decreasing temperatures, despite the marginal effect of temperature on the action potential duration. In 2D models, spiral waves drifted with drifting velocity components affected by both temperature gradient direction and the spiral wave rotation direction. Overall, spiral waves drifted towards the colder tissue region associated with global minimum of excitability. A local perturbation with a temperature of T=28°C was found optimal for spiral wave attraction for the studied conditions. This work provides a preliminary proof-of-concept for a potential prospective technique for rotor attraction. We envision that the insights from this study will be utilize in the future in the design of a new methodology for AF characterization and termination during ablation procedures.

Raised Floor Hybrid Cooled Data Center: Effect on Rack Inlet Air Temperatures When In Row Cooling Units are Installed Between the Racks

2015 ◽  
Author(s):  
Tianyi Gao ◽  
James Geer ◽  
Russell Tipton ◽  
Bruce Murray ◽  
Bahgat G. Sammakia ◽  
...  
Keyword(s):  
Flow Rate ◽  
Data Center ◽  
Heat Load ◽  
Data Centers ◽  
Cooling System ◽  
Air Flow ◽  
Inlet Temperature ◽  
Air Flow Rate ◽  
Air Temperatures ◽  
Cooling Unit

The heat dissipated by high performance IT equipment such as servers and switches in data centers is increasing rapidly, which makes the thermal management even more challenging. IT equipment is typically designed to operate at a rack inlet air temperature ranging between 10 °C and 35 °C. The newest published environmental standards for operating IT equipment proposed by ASHARE specify a long term recommended dry bulb IT air inlet temperature range as 18°C to 27°C. In terms of the short term specification, the largest allowable inlet temperature range to operate at is between 5°C and 45°C. Failure in maintaining these specifications will lead to significantly detrimental impacts to the performance and reliability of these electronic devices. Thus, understanding the cooling system is of paramount importance for the design and operation of data centers. In this paper, a hybrid cooling system is numerically modeled and investigated. The numerical modeling is conducted using a commercial computational fluid dynamics (CFD) code. The hybrid cooling strategy is specified by mounting the in row cooling units between the server racks to assist the raised floor air cooling. The effect of several input variables, including rack heat load and heat density, rack air flow rate, in row cooling unit operating cooling fluid flow rate and temperature, in row coil effectiveness, centralized cooling unit supply air flow rate, non-uniformity in rack heat load, and raised floor height are studied parametrically. Their detailed effects on the rack inlet air temperatures and the in row cooler performance are presented. The modeling results and corresponding analyses are used to develop general installation and operation guidance for the in row cooler strategy of a data center.

scholarly journals The valuation performance of mathematically-optimised, equity-based composite multiples

2017 ◽  
Vol 22 (43) ◽  
pp. 224-250
Author(s):  
Soon Nel ◽  
Niël le Roux
Keyword(s):  
Principal Component Regression ◽  
Principal Component ◽  
Single Factor ◽  
Content Type ◽  
Body Of Knowledge ◽  
Composite Models ◽  
Optimisation Methods ◽  
Key Industries ◽  
Mathematical Optimisation ◽  
Practical Implications

Purpose This paper aims to examine the valuation precision of composite models in each of six key industries in South Africa. The objective is to ascertain whether equity-based composite multiples models produce more accurate equity valuations than optimal equity-based, single-factor multiples models. Design/methodology/approach This study applied principal component regression and various mathematical optimisation methods to test the valuation precision of equity-based composite multiples models vis-à-vis equity-based, single-factor multiples models. Findings The findings confirmed that equity-based composite multiples models consistently produced valuations that were substantially more accurate than those of single-factor multiples models for the period between 2001 and 2010. The research results indicated that composite models produced up to 67 per cent more accurate valuations than single-factor multiples models for the period between 2001 and 2010, which represents a substantial gain in valuation precision. Research implications The evidence, therefore, suggests that equity-based composite modelling may offer substantial gains in valuation precision over single-factor multiples modelling. Practical implications In light of the fact that analysts’ reports typically contain various different multiples, it seems prudent to consider the inclusion of composite models as a more accurate alternative. Originality/value This study adds to the existing body of knowledge on the multiples-based approach to equity valuations by presenting composite modelling as a more accurate alternative to the conventional single-factor, multiples-based modelling approach.

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