scholarly journals Numerical and experimental determination of in-structure temperature profiles

2015 ◽  
Vol 10 (1) ◽  
pp. 65-72 ◽  
Author(s):  
Marek Zozulák ◽  
Dušan Katunský
Keyword(s):  
Temperature Field ◽  
Initial Conditions ◽  
Building Envelope ◽  
The Body ◽  
Temperature Profiles ◽  
Initial Condition ◽  
Start Up ◽  
Outdoor Test ◽  
Building Physics

Abstract When building physics simulations are done initial conditions express the actual hygrothermal state of building envelope. For the temperature field simulations initial condition is represented by the initial temperature in the body profile at the start of heat transfer. In-structure temperature varies quickly so temperature initial conditions are often neglected. Nevertheless in specific cases initial conditions have to be taken into an account even when simple temperature field simulations are done. The contribution shows various temperature initial conditions determination for insulated construction of outdoor test cell. Comparison of measured and calculated temperature profiles in structure shows correctness of start-up pre-calculation initial condition consideration

Hygrothermal Initial Conditions - Case Studies

2016 ◽  
Vol 820 ◽  
pp. 273-278
Author(s):  
Marek Zozulák ◽  
Marián Vertaľ ◽  
Dušan Katunský
Keyword(s):  
Moisture Transfer ◽  
Initial Conditions ◽  
Building Envelope ◽  
The Body ◽  
Initial Condition ◽  
Moisture Condition ◽  
Building Simulations ◽  
Building Components ◽  
Outdoor Test ◽  
Heat And Moisture

In building simulations initial conditions express the actual hygrothermal state of building envelope. For the temperature field simulations initial condition is represented by the initial temperature in the body profile at the start of heat transfer. In-structure temperature varies quickly so temperature initial conditions are often neglected. The contribution shows various temperature initial conditions determination for insulated construction of outdoor test cell. We confirmed importance of setting the initial moisture condition for numerical analysis of complex heat and moisture transfer in multi-layer building components. Comparison of measured and calculated temperature profiles in structure show correctness initial condition consideration.

The Distribution of Temperatures in a Hot/Cold Die Set: The Effect of the Pressure, Temperature, and Material

1995 ◽  
Vol 117 (2) ◽  
pp. 220-227 ◽  
Author(s):  
J. G. Lenard ◽  
M. E. Davies
Keyword(s):  
Initial Conditions ◽  
Control Program ◽  
The Body ◽  
Temperature Fields ◽  
Surface Temperatures ◽  
Direct Measurements ◽  
Die Set ◽  
The Difference ◽  
Interface Pressures

Modern hot metalforming operations require a predictive-adaptive control program in which the predictive component precalculates the necessary parameters—such as temperatures and loads—and the adaptive component sets up, monitors and adjusts the forming equipment. One of the needs of a predictive model of the process is for an understanding of the boundary conditions at the surface of contact. For high temperature operations, one of these conditions is described by the heat transfer coefficient, relating the heat flux and the difference of the temperatures of the contacting surfaces, at the die-workpiece interface. The surface temperatures are, of course, dependent on the distribution of the temperatures within the body of the dies. The determination of these distributions is the topic of the present project. Thermocouples embedded in a cold/hot die set as well as thermocouples placed on the surface of contact are used to monitor the temperature fields, within the body as well as on the surfaces, for various interface pressures, initial temperatures and materials. The results indicate that direct measurements of the temperatures of the contacting surfaces is very difficult and may lead to significant errors. It is recommended that a mathematical model, which uses the measured internal temperatures as initial conditions, should be employed to calculate the contact surface temperatures.

How can inter-specific interferences explain coexistence or confirm the competitive exclusion principle in a chemostat?

2018 ◽  
Vol 11 (08) ◽  
pp. 1850111 ◽  
Author(s):  
Miled El Hajji
Keyword(s):  
Competitive Exclusion ◽  
Initial Conditions ◽  
Exclusion Principle ◽  
Initial Condition ◽  
System Of Differential Equations ◽  
Specific Density ◽  
Competitive Exclusion Principle ◽  
Mutualistic Relationship ◽  
Dependent Growth

In this paper, I consider two species feeding on limiting substrate in a chemostat taking into account some possible effects of each species on the other one. System of differential equations is proposed as model of these effects with general inter-specific density-dependent growth rates. Three cases were considered. The first one for a mutual inhibitory relationship where it is proved that at most one species can survive which confirms the competitive exclusion principle. Initial concentrations of species have great importance in determination of which species is the winner. The second one for a food web relationship where it is proved that under general assumptions on the dilution rate, both species persist for any initial conditions. Finally, a third case dealing with an obligate mutualistic relationship was discussed. It is proved that initial condition has a great importance in determination of persistence or extinction of both species.

Characteristics and mechanisms of the effects of heart rate history on transient AV nodal responses

1996 ◽  
Vol 270 (6) ◽  
pp. H2070-H2080 ◽  
Author(s):  
J. Zhao ◽  
J. Billette
Keyword(s):  
Heart Rate ◽  
Cycle Length ◽  
Initial Conditions ◽  
Fast Rate ◽  
Hysteresis Loops ◽  
Rabbit Heart ◽  
Initial Condition ◽  
Stimulus Interval ◽  
Basic Cycle Length

The characteristics and functional origin of the changes in transient atrioventricular (AV) nodal responses with heart rate history were studied in isolated rabbit heart preparations. For this purpose, ramp stimulation sequences were applied to the atrium from different initial conditions. A ramp decrease and increase in the His-stimulus interval and a reverse sequence consisting of a ramp increase and decrease were performed starting from a control basic cycle length, after 5 min of fast rate, or with 5 min of fast rate inserted between the two ramps. The nodal conduction times (NCT) obtained during the ramp stimulations formed hysteresis loops, the direction, shape, and magnitude of which varied markedly with the nodal history. That is, the nodal response to a given ramp took a variety of forms, depending on the initial condition. The effects of the initial condition also depended on ramp direction and sequence. A paradoxical NCT-recovery relationship (decrease in NCT with shortening His-atrial interval) was consistently observed at the onset of any ramp decrease performed after 5 min of fast rate. These effects also varied with the rate used to change the nodal history. The insertion of a control cycle at every 20th beat during repeated ramp protocols allowed the determination of the contribution of the nodal property of fatigue to these effects. Fatigue was found to account for all observed hysteresis patterns. In conclusion, heart rate history can, by modulating beat-to-beat changes in fatigue, transform transient nodal responses and hysteresis observed during stimulation ramps. Interpretation of transient nodal responses thus requires exact knowledge of previous nodal history.

Heat Conduction in Solids With Random Initial Conditions

1974 ◽  
Vol 96 (4) ◽  
pp. 474-477 ◽  
Author(s):  
G. Ahmadi
Keyword(s):  
Temperature Field ◽  
Heat Conduction ◽  
General Theory ◽  
Unbounded Domain ◽  
Initial Conditions ◽  
Bounded Domains ◽  
Random Initial Condition ◽  
Initial Condition ◽  
Random Initial Conditions ◽  
Random Temperature Field

The problem of heat conduction in solids with random initial condition is studied. A general theory is first discussed and several examples are considered. It is observed that the homogeneity of the random initial condition is sufficient for the homogeneity of the temperature field in an unbounded domain. But in bounded domains the random temperature field becomes nonhomogeneous even though the initial condition is homogeneous.

scholarly journals Heat Transport Analysis in Rectangular Shields Using the Laplace and Poisson Equations

Energies ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1714
Author(s):  
Stefan Owczarek ◽  
Mariusz Owczarek
Keyword(s):  
Temperature Field ◽  
Steady State ◽  
Heat Flow ◽  
Direct Method ◽  
Transient State ◽  
Building Envelope ◽  
Heat Fluxes ◽  
Flow Process ◽  
Infinite Power ◽  
Building Physics

In the design of a building envelope, there is the issue of heat flow through the partitions. In the heat flow process, we distinguish steady and dynamic states in which heat fluxes need to be obtained as part of building physics calculations. This article describes the issue of determining the size of those heat fluxes. The search for the temperature field in a two-dimensional problem is common in building physics and heat exchange in general. Both numerical and analytical methods can be used to obtain a solution. Two methods were dealt with, the first of which was used to obtain the solution in the steady state and the other in the transient. In the steady state a method of initial functions, the basics of which were given by W.Z. Vlasov and A.Y. Lur’e was adopted. Originally MIF was used for analysis of the loads of a flat elastic medium. Since then it was used for solving concrete beams, plates and composite materials problems. Polynomial half-reverse solutions are used in the theory of a continuous medium. Here solutions were obtained by the direct method. As a result, polynomial forms of the considered temperature field were obtained. A Cartesian coordinate system and rectangular shape of the plate were assumed. The problem is governed by the Laplace equation in the steady state and Poisson in the transient state. Boundary conditions in the form of temperature (τ(x), t(y)) or/and flux (p(x), q(y)) can be provided. In the steady state the solution T(x, y) was assumed in the form of an infinite power series developed in relation to the variable y with coefficients Cn depending on x. The assumed solution was substituted into the Fourier equation and after expanding into the Taylor series the boundary condition for y = 0 and y = h was taken into account. From this condition the coefficient Cn can be calculated and, therefore, a closed solution for the temperature field in the plate.

Gender determination of caucasoid hair using image analysis

1993 ◽  
Vol 51 ◽  
pp. 216-217
Author(s):  
T.B. Ball ◽  
W.M. Hess
Keyword(s):  
Image Analysis ◽  
Cross Sections ◽  
Scalp Hair ◽  
The Body ◽  
Equivalent Diameter ◽  
Cross Sectional ◽  
Hair Samples ◽  
Length Width ◽  
Morphological Differences

It has been demonstrated that cross sections of bundles of hair can be effectively studied using image analysis. These studies can help to elucidate morphological differences of hair from one region of the body to another. The purpose of the present investigation was to use image analysis to determine whether morphological differences could be demonstrated between male and female human Caucasian terminal scalp hair.Hair samples were taken from the back of the head from 18 caucasoid males and 13 caucasoid females (Figs. 1-2). Bundles of 50 hairs were processed for cross-sectional examination and then analyzed using Prism Image Analysis software on a Macintosh llci computer. Twenty morphological parameters of size and shape were evaluated for each hair cross-section. The size parameters evaluated were area, convex area, perimeter, convex perimeter, length, breadth, fiber length, width, equivalent diameter, and inscribed radius. The shape parameters considered were formfactor, roundness, convexity, solidity, compactness, aspect ratio, elongation, curl, and fractal dimension.

Is it a Right Assumption That B and Ge are Distributed Randomly After Growing a Strained HBT-Structure?

2002 ◽  
Vol 716 ◽  
Author(s):  
Victor I. Kol'dyaev
Keyword(s):  
Surface Segregation ◽  
Initial Conditions ◽  
Initial Condition ◽  
Basic Assumptions ◽  
Transient Diffusion ◽  
Segregation Process ◽  
Main Observation

AbstractIt is accepted that surface Ge atoms are considered to be responsible for the surface B segregation process. A set of original experiments is carried out. A main observation from the B and Ge profiles grown at different conditions shows that at certain conditions B is taking initiative and determine the Ge surface segregation process. basic assumptions are suggested to self-consistently explain these original experimental features and what is observed in the literature. These results have a strong implication for modeling the B diffusion in Si1-xGex where the initial conditions should be formulated accounting for the correlation in B and Ge distribution. A new assumption for the initial condition to be “all B atoms are captured by Ge” is regarded as a right one implicating that there is no any transient diffusion representing the B capturing kinetics.

Determination of the profile of the temperature field of material heated by continuous laser radiation

2020 ◽  
pp. 51-10
Author(s):  
B.A. Lapshinov ◽  
◽  
N.I. Timchenko ◽  
Keyword(s):  
Temperature Field ◽  
Optical Fiber ◽  
Prolonged Exposure ◽  
Radiation Spectrum ◽  
Visible Range ◽  
Continuous Laser ◽  
Surface Temperature Distribution ◽  
Continuous Radiation ◽  
Spectral Pyrometry

Spectral pyrometry was used to determine the surface temperature distribution of Si, Nb, Cu, and graphite samples when they were locally heated by continuous radiation of an Nd:YAG laser (λ = 1.064 μm). With prolonged exposure to radiation, a stationary temperature field was established in the samples. The thermal spectra were recorded with a small spectrometer in the visible range in the temperature range above 850 K. The optical fiber used to transmit the radiation spectrum to the spectrometer had an additional diaphragm with a diameter of 1 mm located at a certain distance from the fiber end, which ensured the locality of the recorded spectra. The optical fiber moved continuously along the sample, and the spectrometer recorded up to 100 spectra with a frequency of 5-10 Hz. The temperature profile of the samples was calculated based on the results of processing the spectra using the Spectral Pyrometry program.

Determination of Lead Content in Red Colored Lipsticks from Mandalay Market by Flame Atomic Absorption Spectrophotometer

2018 ◽  
Vol 30 (3) ◽  
pp. 167-173
Keyword(s):  
Sampling Procedure ◽  
The Body ◽  
Lead Content ◽  
Social Psychological ◽  
Allowable Limit ◽  
Flame Atomic Absorption ◽  
Therapeutic Benefits ◽  
Flame Atomic Absorption Spectrophotometer ◽  
Exposure Levels

Red colored lipstick is the most widely used cosmetic product. Although lipstick gives a lot of social, psychological and therapeutic benefits, it may harm the consumers. Because some lipsticks contain a considerable amount of heavy metal especially lead. Lead is being used in lipstick mainly for the pigments required to obtain needed colors. Lead accumulates in the body over time and lead-containing lipstick applied several times a day, every day, combined with lead in water and other sources, could add up to significant exposure levels. Therefore, this study was aimed to determine lead content in red colored lipsticks from market. This study was laboratorybased, analytical study by using 25 lipstick samples. Red colored lipsticks were bought from Mandalay Market by random sampling procedure and they were completely coded to avoid the bias. Then, lead content in coded samples was determined by Flame AAS according to International Conference on Harmonization (ICH) guideline. Lead contents of 88% of the lipsticks samples were more than specified limit (20 ppm) of Food and Drug Administration, United States. All of them, lead content was highest in counterfeit lipsticks group. Among the tested lipstick samples, lipstick with lowest lead content was LE-RL 01 (15.74 ppm) and the lipstick with highest lead content was CF-RL 01(60.09 ppm). In conclusion, lead contents of red colored lipsticks (22 out of 25) from market samples were higher than allowable limit (20 ppm).

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