Definition of Commonly Used Day Types (Atmospheric Ambient Temperature Characteristics Versus Pressure Altitude)

There is a misbelief that the same animal has the same thermoneutral zone (TNZ) in different experimental setups. In reality, TNZ strongly depends on the physical environment and varies widely across setups. Current methods for determining TNZ require elaborate equipment and can be applied only to a limited set of experimental conditions. A new, broadly applicable approach that rapidly determines whether given conditions are neutral for a given animal is needed. Consistent with the definition of TNZ [the range of ambient temperature (Ta) at which body core temperature (Tc) regulation is achieved only by control of sensible heat loss], we propose three criteria of thermoneutrality: 1) the presence of high-magnitude fluctuations in skin temperature (Tsk) of body parts serving as specialized heat exchangers with the environment (e.g., rat tail), 2) the closeness of Tsk to the median of its operational range, and 3) a strong negative correlation between Tskand Tc. Thermocouple thermometry and liquid crystal thermography were performed in five rat strains at 13 Ta. Under the conditions tested (no bedding or filter tops, no group thermoregulation), the Ta range of 29.5–30.5°C satisfied all three TNZ criteria in Wistar, BDIX, Long-Evans, and Zucker lean rats; Zucker fatty rats had a slightly lower TNZ (28.0–29.0°C). Skin thermometry or thermography is a definition-based, simple, and inexpensive technique to determine whether experimental or housing conditions are neutral, subneutral, or supraneutral for a given animal.

Download Full-text

Analyzing the Impact of Ambient Temperature Indicators on Transformer Life in Different Regions of Chinese Mainland

The Scientific World JOURNAL ◽

10.1155/2013/125896 ◽

2013 ◽

Vol 2013 ◽

pp. 1-10 ◽

Cited By ~ 1

Author(s):

Cui-fen Bai ◽

Wen-Sheng Gao ◽

Tong Liu

Keyword(s):

Ambient Temperature ◽

Least Squares ◽

Partial Least Squares ◽

Partial Least Squares Regression ◽

Chinese Mainland ◽

Least Squares Regression ◽

Temperature Characteristics ◽

Life Consumption ◽

The Impact ◽

The Relationship

Regression analysis is applied to quantitatively analyze the impact of different ambient temperature characteristics on the transformer life at different locations of Chinese mainland. 200 typical locations in Chinese mainland are selected for the study. They are specially divided into six regions so that the subsequent analysis can be done in a regional context. For each region, the local historical ambient temperature and load data are provided as inputs variables of the life consumption model in IEEE Std. C57.91-1995 to estimate the transformer life at every location. Five ambient temperature indicators related to the transformer life are involved into the partial least squares regression to describe their impact on the transformer life. According to a contribution measurement criterion of partial least squares regression, three indicators are conclusively found to be the most important factors influencing the transformer life, and an explicit expression is provided to describe the relationship between the indicators and the transformer life for every region. The analysis result is applicable to the area where the temperature characteristics are similar to Chinese mainland, and the expressions obtained can be applied to the other locations that are not included in this paper if these three indicators are known.

Download Full-text

Prestress state evolution during thermal activation of memory effect in concrete beams strengthened with external SMA wires

Archives of Civil and Mechanical Engineering ◽

10.1007/s43452-020-00133-y ◽

2020 ◽

Vol 20 (4) ◽

Author(s):

A. Debska ◽

Piotr Gwozdziewicz ◽

A. Seruga ◽

X. Balandraud ◽

J. F. Destrebecq

Keyword(s):

Ambient Temperature ◽

Memory Effect ◽

Concrete Beams ◽

Macroscopic Model ◽

Maximum Temperature ◽

Joule Effect ◽

Mechanical Coupling ◽

State Evolution ◽

Definition Of ◽

Concrete Elements

Abstract The memory effect of shape-memory alloys (SMAs) has opened interesting perspectives to create prestress states in concrete elements. However, the procedure has not been yet fully resolved due to the complex thermomechanical behavior of these alloys, in addition to the practical difficulties of mechanical coupling between SMA and concrete elements. The present study deals with tests on the development of prestressing forces in concrete beams during the thermal cycle required in the procedure. Pre-stretched nickel–titanium wires were externally placed on concrete prismatic beams equipped with strain gauges. As concrete rupture may occur during the heating by the Joule effect, a compromise must be found between the SMA pre-stretch level and the maximum temperature to be applied before returning to ambient temperature. A macroscopic model was developed to analyze this compromise. The complex thermomechanical response of SMAs implies a particular attention in the definition of the ambient temperature and heating conditions for the creation of prestress states in concrete components.

Download Full-text

Behavior of an asphalt mixture MDC-19 under the cycles of ambient temperature in the city of Tunja, Colombia

Respuestas ◽

10.22463/0122820x.1803 ◽

2019 ◽

Vol 24 (1) ◽

pp. 56-64

Author(s):

Carol Rosabeth Sanabria Sanabria ◽

Carlos Hernando Higuera Sandoval

Keyword(s):

Ambient Temperature ◽

Environmental Temperature ◽

Asphalt Mixture ◽

Early Morning ◽

Maximum Temperature ◽

Temperature Cycles ◽

Weather Factor ◽

Asphalt Mix ◽

And Performance ◽

Definition Of

The weather factor plays an important role in the behavior and performance of asphalt mixtures as a surface layer in a flexible pavement structure, not just from the moisture, but also from the environmental temperature. Asphalt layers of the flexible pavements in Tunja city exposes daily to environmental temperature variations, which usually occur when the highest temperatures are reached during the daytime, and the lowest temperatures appear at night and early morning time. Firstly, this research is based , on the definition of the environmental temperature cycles that occur daily in Tunja City, from the analysis of the temperature series. Subsequently, the analysis was done through laboratory tests on an asphalt mix MDC-19 INVIAS type, made and compacted in the laboratory, to determine the influence of the cycles of environmental temperature on its density, stability and flow properties, during 120 daily and continuous temperature cycles, which consist of 12 hours of maximum temperature and 12 hours of minimum temperature to simulate the environmental conditions. As a result of this investigation, the presentation density is presented, presenting a tendency to increase the measurement that increases the temperature cycles and then a decrease in the briquettes of the mixture that have sometimes been until the last cycles. Variations in the resistance to deformation of the analysis mixture were obtained as the ambient temperature cycles were sometimes made, which concludes that the ambient temperature cycles have an influence on the behavior of the asphalt mixture.

Download Full-text

Velocity Temperature Characteristics of Time Domain Reflectometry Cable Length Measurement System

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.225-226.753 ◽

2011 ◽

Vol 225-226 ◽

pp. 753-756

Author(s):

Jian Hui Song ◽

Liang Chen

Keyword(s):

Ambient Temperature ◽

Wave Velocity ◽

Measurement System ◽

Time Domain ◽

Traveling Wave ◽

Time Domain Reflectometry ◽

Length Measurement ◽

Temperature Characteristics ◽

Cable Length ◽

The Time Domain

Traveling wave velocity is the key to the measuring accuracy of the time-domain reflectometry cable length measurement system. The velocity value is affected by many factors. In order to reduce the ambient temperature impact on velocity, the velocity temperature characteristics of time domain reflectometry cable length measurement system are studied. The change law of the traveling wave propagation velocity in the cable with the change in ambient temperature is studied. The velocity temperature error compensation coefficients of traveling wave in the PVC insulated cable is obtained according to the experimental data by measuring the traveling wave velocity in these cables at different temperature. Experimental results show that the measuring accuracy of the time-domain reflectometry cable length measurement system is improved significantly by velocity temperature compensation.

Download Full-text