Different Rates Of Temperature Change Research Articles

A novel method to eliminate the symmetry dependence of fiber coils for shupe mitigation

It is a well-known fact that interferometric fiber optic gyroscopes (IFOGs) are easily distorted by thermal effects and distortion results in the degradation of the performance of these sensors. Changing the fiber coil geometry, increasing the winding symmetry, adding fiber buffer layers around the fiber coil, using different modulation methods for multifunctional integrated optic chips, and using special types of fibers, such as photonic crystal fibers, are some alternative solutions for preventing this degradation. This paper, theoretically and experimentally, investigates not only how different types of fiber coil winding methods behave under different rates of temperature change but also presents a novel method, to the best of our knowledge, to eliminate the Shupe effect, without violating the simplest IFOG scheme. This method rules out the importance of the winding symmetry epochally and the need of any extra treatment for the fiber coil to increase the thermal performance of the system. Regardless of the symmetry of the fiber coil winding, the rate error due to the Shupe effect can be reduced to about ±0.05∘/\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\pm 0.05^\\circ /$$\\end{document}h for any rate of temperature change with this new method according to the experimental results.

Investigation of the performance of mock-target IR thermography for indoor air temperature measurements under transient conditions

Mock Target IR Thermography for indoor air temperature measurement has been proven as an effective methodology for steady-state conditions. This method uses vertical poles of known emissivity placed in a space to measure air temperature by employing IR thermography. Compared to thermocouple / point-by-point measurement, this technique allows obtaining air temperature values in a continuous line. Several poles can be installed in a space ensuring the collection of a large amount of air temperature data entries by taking a single IR image, whereas measurements in large spaces with hundreds of thermocouples would require complicated wiring and data collection hardware. However, for this approach to be more widely considered, such measurement techniques should be adaptable for transient conditions as well, as air temperature can fluctuate and change due to external climatic conditions, occupancy or faults in HVAC equipment. This work aims to investigate if IR Thermography which was only tested in steady-state conditions can be applied to conditions of transient variation of indoor air temperature. For this purpose, measurements under lab conditions and numerical analysis with the use of finite element modelling (FEM) were performed. Specifically, measurements were carried out by using both Mock Target IR thermography and thermocouples, to investigate the precision of IR-obtained transient data. The experiments were conducted in the environmental chamber under controlled conditions. Three types of heating systems (underfloor heating, radiator heating, and ventilation heating) were investigated to ensure that the method is tested under conditions of different heat-emitting devices, as well as different convection and radiation ratios. Validated numerical models were developed using the FEM Multiphysics approach, to extend the scope of the assessment under various conditions and to observe the difference between the mock target pole temperature and air temperature. It was concluded that the mock target IR Thermography performance was accurate for the case of transient air temperature, as well as for different rates of temperature change, with an average temperature deviation of 0.4 [%] according to the experimental measurements and 1.74 [%] based on the numerical simulations.

Cool and warm ionotropic receptors control multiple thermotaxes in Drosophila larvae.

Animals are continuously confronted with different rates of temperature variation. The mechanism underlying how temperature-sensing systems detect and respond to fast and slow temperature changes is not fully understood in fly larvae. Here, we applied two-choice behavioral assays to mimic fast temperature variations and a gradient assay to model slow temperature changes. Previous research indicates that Rhodopsin 1 (Rh1) and its phospholipase C (PLC) cascade regulate fast and slow temperature responses. We focused on the ionotropic receptors (IRs) expressed in dorsal organ ganglions (DOG), in which dorsal organ cool-activated cells (DOCCs) and warm-activated cells (DOWCs) rely on IR-formed cool and warm receptors to respond to temperature changes. In two-choice assays, both cool and warm IRs are sufficient for selecting 18°C between 18°C and 25°C but neither function in cool preferences between 25°C and 32°C. The Rh1 pathway, on the other hand, contributes to choosing preferred temperatures in both assays. In a gradient assay, cool and warm IR receptors exert opposite effects to guide animals to ∼25°C. Cool IRs drive animals to avoid cool temperatures, whereas warm IRs guide them to leave warm regions. The Rh1 cascade and warm IRs may function in the same pathway to drive warm avoidance in gradient assays. Moreover, IR92a is not expressed in temperature-responsive neurons but regulates the activation of DOWCs and the deactivation of DOCCs. Together with previous studies, we conclude that multiple thermosensory systems, in various collaborative ways, help larvae to make their optimal choices in response to different rates of temperature change.

Rates of warming impact oxidative stress in zebrafish (Danio rerio).

Potentially negative effects of thermal variation on physiological functions may be modulated by compensatory responses, but their efficacy depends on the time scale of phenotypic adjustment relative to the rate of temperature change. Increasing temperatures in particular can affect mitochondrial bioenergetics and rates of reactive oxygen species (ROS) production. Our aim was to test whether different rates of temperature increase affect mitochondrial bioenergetics and modulate oxidative stress. We exposed zebrafish (Danio rerio) to warming from 20°C to 28°C over 3, 6, 24 or 48 h, and compared these with a control group that was kept at constant 20°C. Fish exposed to the fastest (3 h) and slowest (48 h) rates of warming had significantly higher rates of H2O2 production relative to the control treatment, and the proportion of O2 converted to H2O2 (H2O2/O2 ratio) was significantly greater in these groups. However, ROS production was not paralleled by differences in mitochondrial substrate oxidation rates, leak respiration rates or coupling (respiratory control ratios). Increased rates of ROS production did not lead to damage of proteins or membranes, which may be explained by a moderate increase in catalase activity at the fastest, but not the slowest, rate of warming. The increase in ROS production at the slowest rate of warming indicates that even seemingly benign environments may be stressful. Understanding how animals respond to different rates of temperature change is important, because the rate determines the time period for phenotypic adjustments and it also alters the environmental thermal signal that triggers compensatory pathways.

Temperature drift compensation of a FOG based on an HKSVM optimized by an improved hybrid BAS-GSA algorithm.

In this paper, the optimal hybrid kernel support vector machine is employed to propose a compensation strategy intended for the temperature drift of a fiber optical gyroscope (FOG). First, the mode of the hybrid kernel with an interpolation and extrapolation capability is constructed, which consists of the radial basis function and the polynomial kernel function. Second, the combination model of the beetle antennae search algorithm and gravitational search algorithm that has both local and global search capability is proposed to optimize the structure-related parameters of a hybrid kernel support vector machine (HKSVM). Finally, the proposed approach is trained and tested using the experimental data of temperature drift at two different rates of temperature change (10°C/min and 5°C/min). In addition, the proposed method is validated against those conventional compensation algorithms. According to the research results, the compensation error (mean squared error) of the proposed approach is reduced by 92% compared to the traditional support vector machine based on the radial basis function.

Within-lake habitat heterogeneity mediates community response to warming trends.

Climate change is rapidly altering many aquatic systems, and life history traits and physiological diversity create differences in organism responses. In addition, habitat diversity may be expressed on small spatial scales, and it is therefore necessary to account for variation among both species and locations when evaluating climate impacts on biological communities. Here, we investigated the effects of temperature and spatial heterogeneity on long-term community composition in a large boreal lake. We used a five-decade time series of water temperature and relative abundance of fish species captured in the littoral zone throughout the summer at 10 discrete locations around the lake. We applied a spatial dynamic factor analysis (SDFA) model to this time series, which estimates the sensitivity of each species to changing water temperature while accounting for spatiotemporal variation. This analysis described the trend in community composition at each sampling location in the lake, given their different trends in temperature over time. The SDFA indicated different magnitude and direction of species responses to temperature; some species increased while others decreased in abundance. The model also identified five unique trends in species abundance across sites and time, indicating residual dynamics in abundance after accounting for temperature effects. Thus, different regions in the lake have experienced different trajectories in community change associated with different rates of temperature change. These results highlight the importance of considering habitat heterogeneity in explaining and predicting future species abundances, and our model provides a means of visualizing spatially-explicit temporal variation in species' dynamics.

Lack of coherence in the warming responses of marine crustaceans

SummaryUnderstanding the extent to which organisms are affected by climate change and are capable of adapting to warming is essential for managing biodiversity. Recent macrophysiological analyses suggest that range‐related responses to warming may be more coherent (less variable) and predictable in marine than in terrestrial systems.To examine this generalization, we investigate basal upper thermal tolerances (measured asCTmax), the extent of their phenotypic plasticity and the impacts of different rates of temperature change on these tolerances, in five species of intertidal crustaceans from three distinct thermal regimes, incorporating South African (RSA) shores and sub‐Antarctic Marion Island (MI).For all species, lower rates of change resulted in lowerCTmax,while acclimation resulted in varied responses depending on the rate of temperature change. At fast rates of temperature change, higher temperature acclimation resulted in elevatedCTmax,while at slow rates of change, acclimation had no effect or resulted in a decline inCTmax.Maximum habitat temperatures recorded at the organisms' microsites were lower than theCTmaxfor theMIpopulations but were aboveCTmaxat slow rates of change forRSApopulations. Thus, populations from more equatorward locations have a lower tolerance of extremes than those from cooler regions. In addition to reduced warming tolerance,RSApopulations had a lower acclimation capacity than their sub‐Antarctic counterparts.We find substantial differences in long‐term responses among groups in different areas as a consequence of spatial variation in the interactions among basal tolerance, phenotypic plasticity and thermal environments. These outcomes emphasize the significance of examining forecasts using a range of data and approaches so that their certainty can be established to inform key policy decisions in a spatially appropriate context.

Phenotypic variance, plasticity and heritability estimates of critical thermal limits depend on methodological context

Summary 1 Biologists have long been concerned with measuring thermal performance curves and limits because of their significance to fitness. Basic experimental design may have a marked effect on the outcome of such measurements, and this is true especially of the experimental rates of temperature change used during assessments of critical thermal limits to activity. To date, the focus of work has almost exclusively been on the effects of rate variation on mean values of the critical limits. 2 If the rate of temperature change used in an experimental trial affects not only the trait mean but also its variance, estimates of heritable variation would also be profoundly affected. Moreover, if the outcomes of acclimation are likewise affected by methodological approach, assessment of beneficial acclimation and other hypotheses might also be compromised. 3 In this article, we determined whether this is the case for critical thermal limits using a population of the model species Drosophila melanogaster and the invasive ant species Linepithema humile. 4 We found that effects of the different rates of temperature change are variable among traits and species. However, in general, different rates of temperature change resulted in different phenotypic variances and different estimates of heritability, presuming that genetic variance remains constant. We also found that different rates resulted in different conclusions regarding the responses of the species to acclimation, especially in the case of L. humile. 5 Although it seems premature to dismiss past generalities concerning interspecific and acclimation-related variation in critical thermal limits, we recommend that conditions during trials be appropriately selected, carefully reported and rigorously controlled.

Strain–temperature hysteresis in concrete under cyclic freeze–thaw conditions

Submerged concrete specimens with 0.55 and 0.65 water–cement ratio were studied under cyclic freeze–thaw conditions at two different rates of temperature change. The strain variation at the centres of each of the specimens was measured using embedded strain-gauges. The strain at the centres of the specimens due to thermal gradients were modelled based only on the temperatures at the surface and the centres of the specimens. It was found that the hysteresis observed in the strain–temperature variations could be attributed to the thermal gradients with significant accuracy even at low rates of temperature change. Thermal gradients were found to be an essential requirement of any comprehensive modelling dealing with cyclic freeze–thaw tests in the laboratory.

Adaptation to warming but not cooling at slow rates of stimulus change in thermal threshold measurements

The relationship between thermal detection threshold and rate of temperature change of the thermal stimulus when slow (<1°C s−1) rates of change are employed was investigated. Using both the reaction time (RT) inclusive Method of Limits and RT exclusive Method of Levels healthy volunteers had warming (WDT) and cooling detection thresholds (CDT) measured at four different rates of temperature change (0.3, 0.5, 0.7 and 1.0°C s−1) from the thenar and/or mental regions using a contact thermode. With the Method of Limits, CDT increased linearly with rate of temperature change suggesting increments were due to RT artefacts. This was further supported by threshold assessment with the Method of Levels which showed CDT were unaffected by the rate of change in the RT exclusive method (P > 0.1). In contrast, WDT did not increase linearly with rate of stimulus temperature change when the Method of Limits was used and threshold assessment with the Method of Levels showed WDT assessed using a 0.3°C s−1 ramp rate were significantly higher than those measured with a 1°C s−1 rate of change (P < 0.05). This study indicates that adaptation to a warming stimulus can occur at faster rates of stimulus change than previously anticipated and identifies differences in warming and cooling pathways in sensitivity to adaptation.

Peculiarities of Dielectric Relaxation in DMAAS Ferroelectric Crystals

This paper presents the results of investigations of the dielectric properties of NH 2 (CH 3 ) 2 Al(SO 4 ) 2 x 6H 2 O crystals performed in a wide frequency range. In particular, the temperature and frequency dependences of the dielectric permittivity were measured in the region of ferroelectric phase at different rates of temperature change. The thermal dipole relaxation with a critical slowing-down at T c 1 was observed at comparatively low frequencies of measuring field. The relaxation connected with the domain freezing takes place at still lower frequencies (below 100 kHz) and was found to be strongly dependent on the rate of the temperature change. It was shown that deuteration results in a noticeable change of the parameters characterising this process including the temperature of domain wall freezing.

C- and Aδ-fibre mediated thermal perception: response to rate of temperature change using method of limits

Studies investigating the effect of rate of temperature change on thermal thresholds have used a variety of different methods and threshold combinations, and many display incomplete reporting of statistical analyses. It has been suggested that C- and A i -fibre mediated thresholds differ in their reaction to different rates of temperature change. Ten healthy female volunteers (aged 18-26 years; mean 21 - S.D. 2.53) undertook cold sensation (CS), warm sensation (WS), cold pain (CP) and heat pain (HP) threshold determinations on the thenar eminence of the dominant hand. Rates of temperature change of 0.5, 1, 2.5 and 4°C/s were used, with a modified method of limits. Adaptation temperature was 32°C and thermode size 3cm 2 3cm. Results showed a significant increase in WS, HP and CP thresholds with increased rates of temperature change (all p < 0.001), but no significant change for CS ( p = 0.653). These results suggest that thresholds with a C-fibre component (WS, HP and CP) and those that are A i -fibre mediated (CS) behave differently. A traditional explanation of measurement artefact alone is insufficient in rationalizing these results, with additional factors potentially involved. Slow rates of temperature change were shown to reduce mean intra-individual differences in recorded threshold values, and also to abolish ceiling effects with HP threshold determinations. Clinically, therefore, using slow rates of temperature change with method of limits has a range of benefits over and above simply minimizing measurement artefact.

Determination of nerve conduction velocity of C-fibres in humans from thermal thresholds to contact heat (thermode) and from evoked brain potentials to radiant heat (CO 2 laser)

This study was designed to estimate and compare nerve conduction velocity (NCV) of cutaneous heat-sensitive C-fibres obtained using two methods. The first is a method based on reaction times to different rates of temperature change produced by a large contact thermode (Thermotest). The second is a novel method based on ultra-late-evoked brain potentials to CO2 laser stimuli with tiny beam sections (< 0.25 mm2), allowing selective and direct activation of very slow conducting afferents. Both methods were applied on three sites of the right leg (foot, knee and thigh) of ten healthy subjects. When based on the reaction times to contact heat, NCV estimations were 0.4 +/- 0.22 m/s for the proximal segment (knee-thigh) and 0.6 +/- 0.23 m/s for the distal segment (foot-knee). When based on the difference in latency of the ultra-late positivity of laser-evoked brain potentials, NCV estimations were respectively 1.4 +/- 0.77 m/s and 1.2 +/- 0.55 m/s. For both methods, the difference in NCV between proximal and distal limb segments was not significant. Although both methods give NCV estimations within the range of C-fibres, the systematic difference between NCV obtained from each method may result from the activation of subpopulations of C-fibres with different NCV depending on the method of stimulation (low-threshold thermal receptors by the thermode and thermal nociceptors by the CO2 laser). Considering the difficulty of investigating peripheral fibres with slow conduction velocities (C-fibres) in humans, the methods used in the present study may be useful tools in both experimental and clinical situations.

The retro-effect in stoichiometric CuAu: a resistometric study

Abstract Long-range ordering and disordering in nearly stoichiometric CuAu (49.4 at% Cu, 50.5 at% Au) has been investigated by dynamic in situ resistometry. Linear cooling and linear heating, starting from constant initial conditions, was performed at different rates of temperature change. For cooling runs the usual effect of undercooling was found, increasing with increasing cooling rate. For heating runs, however, a shift of the transformation temperature to lower temperatures with increasing heating rate was observed. This is similar to what has been previously reported for cyclic measurements ( retro-effect ). This effect is not influenced by isothermal annealing at 300 °C; it is probably connected with the nucleation stage of the phase transformation and thereby with the microstructure of the material.

Behavioural response of larval Atlantic menhaden to different rates of temperature change

Larval Atlantic menhaden Brevoortia tyrannus, spawned off North Carolina (U.S.A.) during the winter, undergo cross‐shelf transport from the western Gulf Stream edge to coastal bays and estuaries. Variation in water flow direction with depth provides larvae the opportunity to enhance shoreward transport, if they can regulate their depth behaviourally. Temperature, which normally decreases with depth on the continental shelf, is one possible cue for depth regulation. Laboratory‐reared larval menhaden of two different ages were exposed to varying relative rates of temperature increases and decreases, which were presented from both above and below the larvae. Temperature decreases from below caused an ascent response in both young and old larvae, but neither responded to this cue from above. The minimum (threshold) relative rates of decrease for initiating ascents were similar (7.9 × 10−2, 10.7 × 10−2° C min−1) for both age larvae as were the minimum absolute amounts of decrease that must occur before a response (0.1, 0.05°C). Young larvae did not respond to a temperature increase, while old larvae ascended regardless of whether the increase was presented from above or below. Threshold relative rates of increase were 8.59 × 10−2°C min−1 from below and 14.79 × 10−2° C min−1 from above. The threshold rates and range of larval speeds during vertical movements were used to calculate vertical temperature gradients that could be perceived. These values were compared to measured gradients in areas inhabited by menhaden larvae. On the continental shelf, detectable temperature gradients appear common for temperature decreases that would occur upon descending and temperature increases upon ascending. However, it is uncommon for larvae to encounter temperature increases upon descending that would initiate an ascent response. These results support the hypothesis that menhaden larvae are capable of using temperature gradients for depth regulation.

Low-frequency dielectric losses near the Curie point in deuteuted triglycine selenate

Abstract Low-frequency dielectric losses near the Curie point at different rates of temperature change, frequency of measuring field, bias electric field strength as well as the X-ray irradiation in deuterated triglycine selenate single crystal have been studied. It was found that the peculiarities of dielectric losses are explained within the low-frequency fluctuation mechanism of dielectric losses

The dynamic properties of trigeminal thermoreceptors following heat-rearing in rats.

Dynamic properties of thermoresponsive units at the caudal trigeminal nucleus are not modified by heat-rearing. The modification of the thermoregulatory system by heat-rearing is unlikely to be a consequence of altered thermoreceptive function at this level. Rats were reared at ambient temperatures of 30 degrees C (heat-reared) and 20 degrees C (controls). Extracellular recordings of thermoresponsive units at the caudal trigeminal nucleus were made while the facial receptive fields of these thermoresponsive units were stimulated with 6 different rates of temperature change (+0.5, +0.1, +0.02, -0.02, -0.1 and -0.5 degrees C/sec). All thermoresponsive units encountered were cold-sensitive. The static maxima were clustered around 13.5 degrees C and did not differ between treatment groups. Dynamic maxima occurred at temperatures around 29-30 degrees C and were not different in thermoresponsive neurones from the two treatment groups. There was no difference between the two treatment groups in the dynamic activity of trigeminal cold-responsive neurones at any of the 42 combinations of temperature and rate of temperature change examined.