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Article
Publication date: 1 January 1992

C. LOMBARD and E.H. MATHEWS

A general numerical method for finding the steady state solution of a cyclic system is presented. The method determines the initial values by enforcing the conditions of…

Abstract

A general numerical method for finding the steady state solution of a cyclic system is presented. The method determines the initial values by enforcing the conditions of periodicity. In this way the initial value is found by integrating through only one cycle, often resulting in a considerable saving of computing effort. The method is applicable to any linear discrete set of difference equations with periodic parameters and forcing functions. The application of the method to a single pole representation of heat flow in buildings is demonstrated.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 2 no. 1
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 1 May 1995

E.H. Mathews and P.A.J. Köhler

The design of optimum pipe and duct networks with available proceduresis difficult, if not impossible. A more efficient procedure that willautomatically produce the…

Abstract

The design of optimum pipe and duct networks with available procedures is difficult, if not impossible. A more efficient procedure that will automatically produce the optimum design is required. Such a procedure is presented in this article. The design is formulated as a constrained nonlinear optimization problem. This problem is solved using a unique numerical optimization algorithm. The solution entails the calculation of the cross sectional dimensions of the ducts and pipes so that the life cycle cost of the network is minimized. The topology equations are derived using graph theory thereby allowing complex networks with loops to be designed numerically. A duct network consisting of a fan and 35 duct sections is designed according to certain specifications. Using the proposed procedure optimum designs were obtained within seconds on a 33 MHz 486 micro‐computer. The procedure was further applied to the optimization of a coal pipeline. It is shown that the optimized solution will cost 14% ($8 million) less than the previous design with conventional design techniques.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 5 no. 5
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 1 February 1994

A.J.C. Stekelenburg, T.H.J.J. Van der Hagen and H.E.A. Van Den Akker

The cross‐correlation flow measurement technique, applied formeasuring the coolant flow rate in a nuclear reactor, was calibrated with theuse of numerical simulations of…

Abstract

The cross‐correlation flow measurement technique, applied for measuring the coolant flow rate in a nuclear reactor, was calibrated with the use of numerical simulations of turbulent flow. The three‐dimensional domain was collapsed into two dimensions. With a two‐dimensional calculation of steady‐state flow with transient thermal characteristics the response of thermocouples to a temperature variation was calculated. By cross‐correlating the calculated thermocouple responses, the link between total flow rate and measured transit times was made. The reliability of the calibration was estimated at ±4.6%. In addition, a measured velocity profile effect was successfully predicted.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 4 no. 2
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 1 August 2015

Jay T. Worobets, Emma R. Skolnik and Darren J. Stefanyshyn

Far infrared radiation (FIR) has been shown to have physiological effects when used as a treatment modality for certain medical conditions. Athletic apparel are currently…

Abstract

Far infrared radiation (FIR) has been shown to have physiological effects when used as a treatment modality for certain medical conditions. Athletic apparel are currently commercially available that are constructed with fabrics that purportedly emit FIR. If apparel with this technology are capable of inducing positive physiological effects, then there may be important implications when worn by an athlete during exercise. The purpose of this study is to examine whether FIR apparel has an effect on oxygen consumption during exercise at submaximal intensities. Twelve male cyclists have completed submaximal incremental cycling tests. Each subject is tested on 4 separate days, twice while wearing a full body Control garment, and twice while wearing a similar garment made out of FIR fabric. Throughout each cycling test, the volume of oxygen uptake is monitored by using a breathing mask and metabolic analysis cart. At lower cycling intensities, the subjects consume statistically significantly less oxygen when wearing the FIR apparel compared to the Control garment, despite performing the same amount of mechanical work. Additional research is required to determine the implication of this effect for a training or competing athlete; however, the results indicate that this apparel technology does elicit a physiological effect.

Details

Research Journal of Textile and Apparel, vol. 19 no. 3
Type: Research Article
ISSN: 1560-6074

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Article
Publication date: 27 July 2018

William Vaughn McCall, Alan Letton, Jordan Lundeen, Doug Case and Francisco J. Cidral-Filho

The application of far-infrared energy to skin is expected to lead to vasodilatation of the skin surface, consequently warming the skin, and promoting sleep induction. The…

Abstract

Purpose

The application of far-infrared energy to skin is expected to lead to vasodilatation of the skin surface, consequently warming the skin, and promoting sleep induction. The purpose of this paper was to test whether bedsheets impregnated with bioceramic far-infrared technology would improve the perception of sleep in a sample of healthy adults.

Design/methodology/approach

Twenty-nine adults consented to participate, randomizing 17 to the far-infrared bedsheets and 12 to the control bedsheets. Two of the control participants dropped out prior to randomization and prior to completing any assessments and therefore are excluded from the analyses. After baseline assessment, participants slept on their randomly assigned sheets for five weeks, followed by a one week “wash out”. Insomnia symptoms were assessed with the Insomnia Severity Index, depression symptoms with the Patient Health Questionnaire, “vigor” and “fatigue” with the Profile of Mood States, and napping behavior with daily sleep diaries.

Findings

During the period of randomization, the participants on the far-infrared sheets reported fewer insomnia symptoms and less napping. This advantage was lost during the wash out period.

Originality/value

Far-infrared technology produces benefits on reported sleep in healthy normal adults.

Details

Research Journal of Textile and Apparel, vol. 22 no. 3
Type: Research Article
ISSN: 1560-6074

Keywords

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