Effect Of Changes In Ambient Temperature Research Articles

Comprehensive Investigation of the Temperature-Dependent Electromechanical Behaviors of Carbon Nanotube/Polymer Composites.

The performances of flexible piezoresistive sensors based on polymer nanocomposites are significantly affected by the environmental temperature; therefore, comprehensively investigating the temperature-dependent electromechanical response behaviors of conductive polymer nanocomposites is crucial for developing high-precision flexible piezoresistive sensors in a wide-temperature range. Herein, carbon nanotube (CNT)/polydimethylsiloxane (PDMS) composites widely used for flexible piezoresistive sensors were prepared, and then the temperature-dependent electrical, mechanical, and electromechanical properties of the optimized CNT/PDMS composite in the temperature range from -150 to 150 °C were systematically investigated. At a low temperature of -150 °C, the CNT/PDMS composite becomes brittle with a compressive modulus of ∼1.2 MPa and loses its elasticity and reversible sensing capability. At a high temperature (above 90 °C), the CNT/PDMS composite softens, shows a fluid-like mechanical property, and loses its reversible sensing capability. In the temperature range from -60 to 90 °C, the CNT/PDMS composite exhibits good elasticity and reversible sensing behaviors and its modulus, resistivity, and sensing sensitivity decrease with an increasing temperature. At room temperature (30 °C), the CNT/PDMS composite exhibits better mechanical and piezoresistive stability than those at low and high temperatures. Given that environmental temperature changes have significant effects on the sensing performances of conductive polymer composites, the effect of ambient temperature changes must be considered when flexible piezoresistive sensors are designed and fabricated.

Calculation of noise field in main transformer room of indoor substation based on thermal-acoustic coupling

In order to calculate the noise field distribution in the main transformer room of an indoor substation accurately, a thermal-acoustic coupling idea was introduced, and a noise field solving the algorithm based on thermal-acoustic coupling was proposed in view of the noise quality loss caused by the effect of ambient temperature changes. Firstly, the fluid-structure coupling model of the main transformer room is established, and the computational fluid dynamics method is used to calculate the flow field distribution and temperature boundary conditions under the action of the heat source; Then, extracting the rheological equation of the environmental boundary conditions in the flow field calculation, and use the difference function to couple the rheological equation to the sound grid to obtain the sound field coupling model under the condition of variable temperature; Finally, the modified parameter acoustic integral equation under the sound field coupling model is calculated based on the conventional Gauss numerical integration method, and the sound field of the main transformer room considering the effect of variable temperature is obtained. The algorithm has been successfully applied in the analysis of the noise field of Xi'an 110 kV Zhenxing Substation, and the error with the measured value is 2.083%.

Magnesium Alloy Composite Water‐Repellent Surface with Durable Corrosion Resistance and Self‐Cleaning Behavior

Magnesium (Mg) alloys have poor corrosion resistance, higher requirements for corrosion resistance of the coating, and the changes in the environment in the actual application are complicated and diverse. Therefore, it is urgent to develop bio‐inspired water‐repellent surfaces (WRSs) with long‐lasting corrosion resistance and multiple excellent properties for Mg alloys. In this study, a composite water‐repellent surface (CWRS) with long‐lasting corrosion resistance and self‐cleaning behavior is prepared by combining laser processing, hydrothermal treatment, and immersion method on the Mg alloy surface. The effect of ambient temperature changes on the wettability and corrosion resistance of the CWRS is investigated. The experimental results showed that a uniform and dense CWRS with a film thickness of 36 μm could be prepared on the Mg alloy surface at an ambient temperature of 180 °C, demonstrating excellent corrosion resistance and self‐cleaning behavior. In addition, in the harsh salt spray test, it is found that even if the superhydrophobicity of the CWRS was lost, the surface still has good corrosion resistance. Multifunctional CWRSs have become a research hotspot, and it is of great significance to promote the application of Mg alloys in actual working conditions.

Non-stressful temperature changes affect transgenerational phenotypic plasticity across the life cycle of Arabidopsis thaliana plants.

Plants respond in a plastic manner to seasonal changes, often resulting in adaptation to environmental variation. Although much is known about how seasonality regulates developmental transitions within generations, transgenerational effects of non-stressful environmental changes are only beginning to be unveiled. This study aimed to evaluate the effects of ambient temperature changes on the expression of transgenerational plasticity in key developmental traits of Arabidopsis thaliana plants. We grew Columbia-0 plants in two contrasting temperature environments (18 and 24 °C) during their whole life cycles, or the combination of those temperatures before and after bolting (18-24 and 24-18 °C) across two generations. We recorded seed germination, flowering time and reproductive biomass production for the second generation, and seed size of the third generation. The environment during the whole life cycle of the first generation of plants, even that experienced before flowering, influenced the germination response and flowering time of the second generation. These effects showed opposing directions in a pattern dependent on the life stage experiencing the cue in the first generation. In contrast, the production of reproductive biomass depended on the immediate environment of the progeny generation. Finally, the seed area of the third generation was influenced positively by correlated environments across generations. Our results suggest that non-stressful environmental changes affect the expression of key developmental traits across generations, although those changes can have contrasting effects depending on the parental and grandparental life stage that perceives the cue. Thus, transgenerational effects in response to non-stressful cues might influence the expression of life-history traits and potential adaptation of future generations.

Compensation of Rotary Encoders Using Fourier Expansion-Back Propagation Neural Network Optimized by Genetic Algorithm.

The measurement accuracy of the precision instruments that contain rotation joints is influenced significantly by the rotary encoders that are installed in the rotation joints. Apart from the imperfect manufacturing and installation of the rotary encoder, the variations of ambient temperature could cause the angle measurement error of the rotary encoder. According to the characteristics of the periodicity of the angle measurement at the stationary temperature and the complexity of the effects of ambient temperature changes, the method based on the Fourier expansion-back propagation (BP) neural network optimized by genetic algorithm (FE-GABPNN) is proposed to improve the angle measurement accuracy of the rotary encoder. The proposed method, which innovatively integrates the characteristics of Fourier expansion, the BP neural network and genetic algorithm, has good fitting performance. The rotary encoder that is installed in the rotation joint of the articulated coordinate measuring machine (ACMM) is calibrated by using an autocollimator and a regular optical polygon at ambient temperature ranging from 10 to 40 °C. The contrastive analysis is carried out. The experimental results show that the angle measurement errors decrease remarkably, from 110.2″ to 2.7″ after compensation. The mean root mean square error (RMSE) of the residual errors is 0.85″.

The effects of ambient temperature changes on foodborne illness outbreaks associated with the restaurant industry

Foodborne illness outbreaks generate serious socioeconomic costs in the United States. Among many causes, the effects of weather change and the habit of frequently dining out at restaurants are very important topics for researchers, because ambient temperature change may influence the entire process of food consumption from farms to tables, and restaurants are considered to be the most predominant single location responsible for foodborne illness outbreaks. However, few studies have examined both factors simultaneously, although empirical findings support a significant relationship between each factor and foodborne illness outbreaks. Therefore, the objective of this study is to link the effects of ambient temperature change with foodborne illness outbreaks in restaurant business settings. Furthermore, this study aims to identify how restaurant firms have performed compared with others in regard to foodborne illness outbreaks. Finally, this study intends to suggest how restaurant firms can reduce or prevent the prevalence of foodborne illness outbreaks.

Effect of Ambient Temperature Changes on Blood Flow in Anterior Cerebral Artery of Patients with Skull Prosthesis

In many cases, an injury to the head leads to the replacement of a part of the skull with materials such as titanium and polyether ether ketone. Three-dimensional heads model of 15 healthy individuals and 13 patients were prepared. The models were simulated using thermal fluid structure interaction analysis to evaluate the effects of cold (5°C) and hot (55°C) temperatures of the skull on the conditions of blood flow in the anterior cerebral artery. The results showed negligible changes (<3%) in wall shear stress (WSS) vessel and von Mises stress between the healthy individuals and patients both at 25°C and 55°C. However, at 5°C, the values of these 2 parameters in the patients were 2.1 and 2.5 times those in healthy individuals, respectively. The value of WSS in healthy individuals and the patients in cold temperature was 1.2 and 2.9 times those at normal temperature. The corresponding values for von Mises stress were 1.1 and 2.2, respectively. Accordingly, the stress changes between cold and hot ambient temperatures were found to be negligible in all samples. The changes in stress were significant only for the patients when exposed to cold ambient temperature, and only in patients, exposure to a cold ambient temperature significantly increased the risks of vascular aneurysm and damage to the brain tissue surrounding the blood vessels. These risks were found to be negligible for both healthy individuals and patients when exposed to hot ambient temperature and also for healthy individuals exposed to cold ambient temperature.

Equivalent full-load hours for assessing climate change impact on building cooling and heating energy consumption in large Asian cities

Estimating cooling and heating energy requirements is an integral part of designing and managing buildings. Further, as buildings are among the largest energy consumers in cities, the estimates are important for formulating effective energy conservation strategies. Where complex hourly simulation models are not favored, such estimates may be derived by simplified methods that are less computationally intensive but still provide results that are reasonably close to those obtained from the more complicated approach. The equivalent full load hours (EFLH) method is a simplified energy estimation method that has recently gained popularity. It offers a straightforward means of evaluating energy efficiency programs. However, to date, easily accessible EFLH data exist only for a very limited number of countries in North America and Europe, but not Asia. This current work provides previously unavailable monthly EFLH data for building cooling and heating in three large Asian cities, viz. Hong Kong, Seoul and Tokyo. To assess the effects of changing temperature over the course of decades on building cooling and heating energy consumption, EFLH data are calculated for three time periods: past (1983–2005), present (2006–2014) and future (2015–2044). The projections for the future time period are based on the climate scenarios Representative Concentration Pathways (RCPs) 4.5 and 8.5 of the Intergovernmental Panel on Climate Change (IPCC) Fifth Assessment Report. RCP-4.5 assumes a stabilization of future greenhouse gas (GHG) emissions followed by a reduction, while RCP-8.5 assumes their further increase. From the EFLH data, considering just the effects of ambient temperature changes, it is projected the total energy required to heat and/or cool residential dwellings in Hong Kong, Seoul and Tokyo to increase by 18.3%, 4% and 10.4%, respectively over 62years from 1983 to 2044 in the case of RCP-4.5, and by 23.3%, 9.3% and 15.8%, respectively in the case of RCP-8.5. This shows that even with future stabilization and reduction of GHG emissions, as per scenario RCP-4.5, the energy needs of the three cities for building heating and cooling combined can be expected to increase over the next few decades. This has significant implications, namely increased demands for additional primary energy, which will result in further GHG emissions. These effects, however, can be controlled with adjustments to the electricity fuel mix of each location, and also by use of more efficient heating, ventilation and air-conditioning (HVAC) devices.

Functional Assessment of Cardiac Responses of Adult Zebrafish (Danio rerio) to Acute and Chronic Temperature Change Using High-Resolution Echocardiography.

The zebrafish (Danio rerio) is an important organism as a model for understanding vertebrate cardiovascular development. However, little is known about adult ZF cardiac function and how contractile function changes to cope with fluctuations in ambient temperature. The goals of this study were to: 1) determine if high resolution echocardiography (HRE) in the presence of reduced cardiodepressant anesthetics could be used to accurately investigate the structural and functional properties of the ZF heart and 2) if the effect of ambient temperature changes both acutely and chronically could be determined non-invasively using HRE in vivo. Heart rate (HR) appears to be the critical factor in modifying cardiac output (CO) with ambient temperature fluctuation as it increases from 78 ± 5.9 bpm at 18°C to 162 ± 9.7 bpm at 28°C regardless of acclimation state (cold acclimated CA– 18°C; warm acclimated WA– 28°C). Stroke volume (SV) is highest when the ambient temperature matches the acclimation temperature, though this difference did not constitute a significant effect (CA 1.17 ± 0.15 μL at 18°C vs 1.06 ± 0.14 μl at 28°C; WA 1.10 ± 0.13 μL at 18°C vs 1.12 ± 0.12 μl at 28°C). The isovolumetric contraction time (IVCT) was significantly shorter in CA fish at 18°C. The CA group showed improved systolic function at 18°C in comparison to the WA group with significant increases in both ejection fraction and fractional shortening and decreases in IVCT. The decreased early peak (E) velocity and early peak velocity / atrial peak velocity (E/A) ratio in the CA group are likely associated with increased reliance on atrial contraction for ventricular filling.

Chikungunya virus in non-mammalian species: a possible new reservoir

Chikungunya virus (CHIKV) is an arbovirus distributed widely in tropical regions of the world that causes a febrile and often painful disease in adults and children. Recent outbreaks of CHIKV infection in the Caribbean have raised concerns about establishment of this virus in North America. A significant question about the transmission cycle of CHIKV is whether non-human reservoir hosts are important in maintenance or transmission of the virus. We conducted experimental infections with CHIKV and discovered that several reptiles and amphibians developed viremia of sufficient magnitude to possibly serve as reservoir hosts. One or two strains of CHIKV were inoculated into a variety of ball pythons, Burmese pythons, Northern garter snakes, American alligators, green iguanas, painted turtles, leopard frogs, Bufo species toads and cane toads. Viremia was not detected in alligators or cane toads but all other species developed viremia at variable magnitude. Peak viremia in the other species varied from 2.8 (Burmese pythons) to 4.7 (leopard frogs) log10 pfu/ml. We also conducted experiment to evaluate the effect of ambient temperature changes to monitor the “over wintering” capabilities of CHIKV in snakes. Northern garter snakes were inoculated a South African strain of CHIKV at temperatures of 16 C versus 26 C and tested for viremia. The snakes kept at 26 C developed a short term viremia, whereas in snakes kept at 16 C, the virus was maintained for a longer period and viremia titers as high as 7.2 log10 pfu/ml were achieved when animals were subsequently slowly warmed to 26 C.

The Effect of Ambient Temperature Changes on Micturition in Infants ‒ A Study of 800 Infants Aged up to 12 Months

Background: Cold may aggravate urge symptoms in patients with frequency/urgency syndromes. Objectives: This paper attempts to establish the correlation between the changes in three variables, namely the changes of ambient temperature, age and weight of conscious infants and their micturition rate. Materials and Methods: The time interval between the napkin removal and micturition was recorded, in order to establish the relationship between environmental temperature changes and urination. Results: Micturition occurred in response to decreased skin temperature of the lower trunk, during the first minute interval of napkin removal, in 287 of the infants (35.9%). Totally, 428 infants (53.5%) voided in a 5 minute interval. The younger infants urinated more frequently and also faster, in relation to ambient temperature changes. Conclusions: We concluded that the occurrence of urination, as a response to cooling stimulation of the lower trunk, is correlated with infants’ age and amount of environmental temperature degree.

Effect of temperature on calibration quality of structured-light three-dimensional scanners.

This paper presents the outcome of research into the effects of ambient temperature changes on structured-light three-dimensional (3D) scanners. The tests were conducted in a thermal chamber and consisted of a comparison of the 3D measurement of a special reference unit (made of a carbon composite) performed at different temperatures, with measurements performed at the calibration temperature. A contact measuring arm with temperature compensation was used as a reference. Based on the results of these experiments, we propose a method that allows us to extend the existing scanner calibration method by using a temperature-correction procedure that is based on linear and nonlinear mathematical models. An exemplary application of this procedure has shown that the range of temperatures in which scanner accuracy is within declared limits can be increased 11-fold.

Measurement of electric field enhanced optical absorption in hydrogenated amorphous silicon

AbstractOptical properties of amorphous semiconductors are influenced by applied or built‐in electric fields. Measurements of the optical absorption change of device grade intrinsic hydrogenated amorphous silicon were performed indirectly by measuring the optical transmission of the samples with and without an applied DC electric field. Effects of ambient temperature changes were limited by strict control of the ambient temperature. Temperature effects caused by self‐heating of the samples were compensated in two different ways to ensure the validity of the results. The influence of temperature change on optical absorption was identified and compensated by the analysis of measurements of multiple samples with different levels of power dissipation brought about by sample conductivity variations. The second method of temperature compensation consisted of determining the temperature change of each sample during the measurements, modelling absorption coefficient change caused by the temperature change and by subtracting the calculated absorption change caused by the temperature change from the measured absorption change. Results of both methods of temperature compensation are in good agreement. The obtained results are also in agreement with the results of other researchers up to photon energies slightly above the mobility edge, where our measurements exhibit a slightly different dependency on photon energy than previously published measurements. (© 2014 WILEY‐VCH Verlag GmbH &amp; Co. KGaA, Weinheim)

Evaporative system for water and beverage refrigeration in hot countries

The present study proposes an evaporative refrigerating system used to keep water or other beverages cool in hot arid regions. The system uses a flow of air that flows around a water container, which is wrapped in a wet fabric. The air before being introduced could be dehumidified and cooled to capture more quantity of water vapour. A mathematical model has been developed to describe the system behaviour and the model has been solved numerically. The effects of many parameters on the system performance have been investigated. Results showed that the suurounding pressure around the tank has a significant effect. A cross-over value of mass flowrate at which the effect of ambient temperature changes is found. The results obtained are found to be consistent with the available literature data.

Noninvasive Heart Rate Measurement Using a Digital Egg Monitor in Chicken and Turkey Embryos

Abstract Monitoring the life status of a developing embryo is very useful, especially during last days of incubation when hatching could potentially be assisted if deemed necessary. A commercially available digital egg monitor (Buddy, Vetronic Services, Devon, UK) uses noninvasive methodology to monitor the heart rate of an embryo by measuring the amount of infrared light absorbed by embryonic blood. Thirty specific pathogen-free (SPF) chicken eggs (29 fertile) were incubated at 37.8 ± 0.1°C and the heart rate of each embryo was measured. Heart rates were first detectable in 13 eggs at day 6 of incubation. At day 7, an average heart rate of 170 ± 20 beats/min was detected in all 29 fertile eggs, which is comparable to reported values. Ten additional SPF chicken eggs were evaluated at day 13 of incubation to test the effects of ambient temperature changes on embryonic heart rate. Embryonic heart rates dropped from 262 to 106 beats/min in eggs kept at room temperature (25°C) for 90 minutes and to <60 beats/...

Improvements in microwave power measurements through the use of feedback

The measurement of microwave power by calorimetric and bolometric methods, together with problems inherent in these types of measurements, are discussed. The methods have high inherent accuracies but in their simplest form suffer from abnormally long time-constants and the effect of ambient-temperature changes. Methods are discussed for lessening the effect of these problems. The long time-constants associated with measurements of this type can be greatly decreased by the proper use of feedback. The effect of ambient-temperature changes can be minimized by the use of a balanced structure in which two identical power-sensing elements are exposed to the same environmental conditions.

Fixed attenuators consisting of a network of identical resistors

Fixed attenuators constructed of identical resistors have advantages of freedom from distortion by the stray self-inductance of the resistors and freedom from the effects of ambient temperature changes. A suitable form for such attenuating networks is described. It is possible to design a network of this form to give attentuation in any ration N to 1, where N is an integer. The minimum number of resistors needed for any value of N is not excessive, being less than seven resistors per decade of N. A table is given which makes the calculation of an optimum network very easy for any value of N up to 400.

Variations in the characteristics of some corona-stabilizer tubes

The variations in the characteristics of several 500 V corona-stabilizer tubes have been studied in detail experimentally. Variations of striking voltage and running voltage from tube to tube have been recorded and the effects of ambient-temperature changes and of excess current on tube characteristics have been noted. The results of this work are presented together with some information on the running-voltage drifts to be expected during the first 1200 hours of life. The properties of tubes run with reversed polarity are also discussed.

Pressure-Temperature Relations in Gas-Filled (Class III) Thermometers

Abstract Fundamental relations are presented for the pressure within the system of a thermometer or thermal system charged with a perfect gas. An expression is developed which gives the approximate pressure in terms of bulb temperature, ambient temperature, and ratio of bulb volume to ambient volume, this being sufficiently accurate if the volume change of the pressure-responsive element is small. An exact equation for the pressure in the system is developed in terms of the temperatures and volumes of bulb, capillary, and pressure-responsive element, and the volume change of the pressure-responsive element, assuming the volume change to be linear with pressure change. From this relation, means are developed for determining the necessary charging pressure to give a specified pressure change when the bulb is varied through a specified temperature span. An example is included in the Appendix in which charging pressure, pressure-temperature curve, and the effect of ambient-temperature changes are computed by means of the exact expressions developed.