Effect Of Thermal Environment Research Articles

Effect of Thermal Environment and Peripheral Loading on Axisymmetric Vibrations of Non-uniform FG Circular Plates via Generalized Differential Quadrature Method

In this article, axisymmetric vibrations of a non-uniform functionally graded circular plate subjected to uniform in-plane peripheral loading and non-linear temperature rise across the thickness have been analyzed on the basis of classical theory of plates. The thickness of the plate is assumed to vary exponentially along the radial direction. The plate material is graded in thickness direction using a power-law model and its mechanical properties are temperature-dependent. Keeping the uniform thermal environment over the top and bottom surfaces, the equations for thermoelastic equilibrium and axisymmetric motion for such a plate model have been derived by Hamilton’s energy principle. Employing generalized differential quadrature method, the frequency equations for clamped and simply supported plates have been obtained and solved numerically using MATLAB. The lowest three roots have been retained as the frequencies for the first three modes of vibration. The influence of various parameters, such as power-law index, in-plane force parameter and temperature difference with varying values of thickness parameter, has been analyzed on the vibration characteristics of the plate. By allowing the frequency to approach zero, the critical buckling loads with varying values of other parameters have been computed. The benchmark results for linear as well as uniform temperature rise have also been computed. The validity of the present technique is verified by comparing the results with the published work.

Field study of pedestrians' comfort temperatures under outdoor and semi-outdoor conditions in Malaysian university campuses.

Difficulties in controlling the effects of outdoor thermal environment on the human body are attracting considerable research attention. This study investigated the outdoor thermal comfort of urban pedestrians by assessing their perceptions of the tropical, micrometeorological, and physical conditions via a questionnaire survey. Evaluation of the outdoor thermal comfort involved pedestrians performing various physical activities (sitting, walking, and standing) in outdoor and semi-outdoor spaces where the data collection of air temperature, globe temperature, relative humidity, wind speed, solar radiation, metabolic activity, and clothing insulation data was done simultaneously. A total of 1011 participants were interviewed, and the micrometeorological data were recorded under outdoor and semi-outdoor conditions at two Malaysian university campuses. The neutral temperatures obtained which were 28.1°C and 30.8°C were within the biothermal acceptable ranges of 24-34°C and 26-33°C of the PET thermal sensation ranges for the outdoor and semi-outdoor conditions, respectively. Additionally, the participants' thermal sensation and preference votes were highly correlated with the PET and strongly related to air and mean radiant temperatures. The findings demonstrated the influence of individuals' thermal adaptation on the outdoor thermal comfort levels. This knowledge could be useful in the planning and designing of outdoor environments in hot and humid regions to create better thermal environments.

Effect of different thermal environments on yield and yield attributes of different mustard genotypes under Chhattisgarh plain climatic conditions

The present investigation entitled “Effect of different thermal environments on Yield and yield attributes of different mustard genotypes under Chhattisgarh plain climatic conditions” was carried out at the research farm, I.G.K.V., Raipur during rabi season of 2015-2016. Dry matter accumulation was significantly maximum in crop sown on 25th November and thereafter the rate of dry matter accumulation declined due to delayed in sowing up to 15th December. Leaf area index was faster right from 25 DAS to 55 DAS with maximum values at 55 DAS in case of crop sown on 25th November as compared to delayed sown crop. Highest siliqua length was recorded in crop sown on 25th November with a maximum value of 6.23 cm in variety PT-303 and minimum in variety PT-30 (5.11 cm). The maximum number of seeds siliqua-1 was recorded in crop sown on 25th November in variety Pusa Mustard-26 (13.60) while the lowest were recorded in crop sown on 15th December in variety PT-30 (11.20) and 1000-seed weight was also recorded maximum in crop sown on 25th November in variety Pusa Mustard (6.01 g) while lowest was recorded from variety PT-30 (4.93 g) crop sown on 15th December. Highest stover and seed yield were recorded in crop sown on 25th November as compared to delayed sowings. Among the varieties, higher seed yield was recorded from Pusa mustard-26 in all thermal environments as compared to other varieties.

Investigating dynamic response of nonlocal functionally graded porous piezoelectric plates in thermal environment

In this research, thermal and electrical effects on dynamic response of a porous nano-sized plate modeled by a nonlocal higher-order refined plate model have been explored in detail. A hyperbolic shear stain function has been used. The porous material considered in this research may have uniform or non-uniform porosity distribution across the cross section. Stain gradient effects have also been considered for more accurate modeling of the scale-dependent plate. Hamilton's rule has been employed for establishing the governing equations. Derived findings by differential quadrature (DQ) method have been validated with those represented in previous researches. The effects of thermal environment, electrical environment, nonlocal scale, and porous material on dynamic behaviors of foam-based nanoplate have been explored.

The effect of cracks and thermal environment on free vibration of FGM plates

The free vibration parameters of cracked functionally graded material (FGM) plates with nonlinear varying thickness according to the symmetric parabola function under temperature is studied in this paper. The temperature transfers through the thickness of the FGM plate and material properties of the plate are distributed power law in the thickness direction and depend on the temperature. The formulas were developed based on Shi's third-order shear deformation theory and the phase field theory in destructive mechanics. The results of the present approach are compared with the existing literature for the validation. The free vibration frequencies of the plate are calculated depending on various parameters such as crack length, crack angle, plate length ratio, temperature, volume fraction index and boundary conditions. In addition, the effect of plate edges and symmetrical parabolic thickness shapes on the natural frequencies of FGM plates are also studied.

寝室内環境が睡眠の質に与える影響 （第 6 報）異なる季節における寝返り後時間経過を考慮した人体熱負荷が睡眠に及ぼす影響

寝室内環境が睡眠の質に与える影響 （第 6 報）異なる季節における寝返り後時間経過を考慮した人体熱負荷が睡眠に及ぼす影響

Thermal Environment of Urban Schoolyards: Current and Future Design with Respect to Children’s Thermal Comfort

Urban outdoor thermal conditions, and its impacts on the health and well-being for the city inhabitants have reached increased attention among biometeorological studies during the last two decades. Children are considered more sensitive and vulnerable to hot ambient conditions compared to adults, and are affected strongly by their thermal environment. One of the urban outdoor environments that children spend almost one third of their school time is the schoolyard. The aims of the present manuscript were to review studies conducted worldwide, in order to present the biophysical characteristics of the typical design of the urban schoolyard. This was done to assess, in terms of bioclimatology, the interactions between the thermal environment and the children’s body, to discuss the adverse effects of thermal environment on children, especially the case of heat stress, and to propose measures that could be applied to improve the thermal environment of schoolyards, focusing on vegetation. Human thermal comfort monitoring tools are mainly developed for adults, thus, further research is needed to adapt them to children. The schemes that are usually followed to design urban schoolyards create conditions that favour the exposure of children to excessive heat, inducing high health risks to them. The literature survey showed that typical urban schoolyard design (i.e., dense surface materials, absence of trees) triggered high surface temperatures (that may exceed 58 °C) and increased absorption of radiative heat load (that may exceed 64 °C in terms of Mean Radiant Temperature) during a clear day with intense solar radiation. Furthermore, vegetation cover has a positive impact on schoolyard’s microclimate, by improving thermal comfort and reducing heat stress perception of children. Design options for urban schoolyards and strategies that can mitigate the adverse effects of heat stress are proposed with focus on vegetation cover that affect positively their thermal environment and improve their aesthetic and functionality.

Effect of early thermal environment on the morphology and performance of a lizard species with bimodal reproduction.

Early developmental environments influence life-history traits and survival of reptiles. In fact, rising global temperatures have already caused widespread extinctions among lizards. Viviparous species might be more susceptible to increasing temperatures because of their inability to meet their energetic demands following rapid environmental changes. Nevertheless, we do not yet fully understand how lizards with different reproductive modes can respond to climate change. We investigated the effect of both maternal thermal environment during pregnancy and incubation temperature on hatchling morphology and physiological performance of two populations of the lizard Saiphos equalis differing in their mode of reproduction, to test whether reproductive mode affects the ability to buffer against rising temperatures. Gravid females from both populations were subjected to current or projected end-of-century (future) thermal environments, to evaluate differences in the body size, growth rate, thermal preference, and locomotor performance of their offspring. Our results show that independently of the mode of reproduction, high temperatures accelerated gestation periods. Thermal environments did not affect hatchling thermal preference, but viviparous hatchlings consistently preferred lower temperatures. Unlike viviparous lizards, oviparous hatchlings incubated under future temperatures were smaller and had a lower growth rate compared to current-incubated hatchlings. Finally, thermal environments did not affect hatchling endurance and speed when controlling for body size. Our results show that global warming is likely to have a negative impact on S. equalis, but suggest that some of its effects may be ameliorated by maternal responses during pregnancy, particularly in viviparous populations.

Effect of thermal environment on sleep quality in actual bedroom in summer by sleep stages analysis

AbstractThis field survey was conducted during summer in actual bedrooms and used polysomnography to evaluate the effect of thermal environment on sleep quality by analyzing electroencephalogram, electro‐oculogram, and electromyogram signals, which were continuously measured during sleep. It was found that the effect of the thermal environment (ie, air temperature, air velocity, and air turbulence) on sleep quality varied according to the sleep cycle and stages. The effect of air turbulence depended mainly on the air temperature. At low or neutral temperatures, air turbulence had negative effects on sleep quality, whereas under warm temperatures, air turbulence had negligible effects on sleep quality.

Inexpensive Home Infrared Living/Environment Sensor with Regional Thermal Information for Infant Physical and Psychological Development

The use of home-based image sensors for biological and environmental monitoring provides novel insight into health and development but it is difficult to evaluate people during their normal activities in their home. Therefore, we developed a low-cost infrared (IR) technology-based motion, location, temperature and thermal environment detection system that can be used non-invasively for long-term studies in the home environment. We tested this technology along with the associated analysis algorithm to visualize the effects of parental care and thermal environment on developmental state change in a non-human primate model, the common marmoset (Callithrix jacchus). To validate this system, we first compared it to a manual analysis technique and we then assessed the development of circadian rhythms in common marmosets from postnatal day 15–45. The semi-automatically tracked biological indices of locomotion velocity (BV) and body surface temperature (BT) and the potential psychological index of place preference toward the door (BD), showed age-dependent shifts in circadian phase patterns. Although environmental variables appeared to affect circadian rhythm development, principal component analysis and signal superimposing imaging methods revealed a novel phasic pattern of BD-BT correlation day/night switching in animals older than postnatal day 38 (approximately equivalent to one year of age in humans). The origin of this switch was related to earlier development of body temperature (BT) rhythms and alteration of psychological behavior rhythms (BD) around earlier feeding times. We propose that this cost-effective, inclusive sensing and analytic technique has value for understanding developmental care conditions for which continual home non-invasive monitoring would be beneficial and further suggest the potential to adapt this technique for use in humans.

Large Amplitude Free Vibrations of FGM Beams on Nonlinear Elastic Foundation in Thermal Field Based on Neutral/Mid-plane Formulations

The present research deals with the small and large amplitude free vibrations of thick functionally graded material (FGM) beams. Beams are resting on an elastic foundation which consists of the Winkler layer, shear layer and nonlinear springs. The effect of uniform temperature elevation is also included into the formulation. A third-order shear deformation beam theory is adopted as the basic assumption of the formulation which satisfies the traction-free boundary conditions on the top and bottom surfaces. Using two different formulations, i.e. the mid-surface-based formulation and the neutral surface-based formulation, the governing equations of motion are established. For the case of beams with immovable edges in in-plane direction and simply supported in flexure, the governing equations are given in a new presentation. These equations are solved using the two-step perturbation technique. Closed-form expressions are provided to obtain the small and large amplitude natural frequencies of the FGM beam resting on nonlinear elastic foundation and operating in thermal environment. Numerical results are given to discuss the effects of thermal environment, elastic foundation parameters, different formulations, and the geometrical parameters.

Effect of In-Plane Load and Thermal Environment on Buckling and Vibration Behavior of Two-Dimensional Functionally Graded Tapered Timoshenko Nanobeam

Abstract In this work, buckling and vibration characteristics of two-dimensional functionally graded (FG) nanobeam of nonuniform thickness subjected to in-plane and thermal loads have been analyzed within the frame work of Timoshenko beam theory. The beam is tapered by linear variation in thickness along the length. The temperature-dependent material properties of the beam are varying along thickness and length as per a power-law distribution and exponential function, respectively. The analysis has been presented using Eringen’s nonlocal theory to incorporate the size effect. Hamilton’s energy principle has been used to formulate the governing equations of motion. These resulting equations have been solved via generalized differential quadrature method (GDQM) for three combinations of clamped and simply supported boundary conditions. The effect of in-plane load together with temperature variation, nonuniformity parameter, gradient indices, nonlocal parameter, and slenderness ratio on the natural frequencies is illustrated for the first three modes of vibration. The critical buckling loads in compression have been computed by putting the frequencies equal to zero. A significant contribution of in-plane load on mechanical behavior of two-directional functionally graded nanobeam with nonuniform cross section has been noticed. Results are in good accordance.

Structural performance of 3D-printed composites under various loads and environmental conditions

Sandwich-structured composites are in high demand in various industries, and additive manufacturing has proven its ability to meet this demand. As a result of the advances in three-dimensional (3D) printing techniques, 3D-printed polymers have received considerable attention in fabrication of sandwich structures with complex geometries. This paper is concerned with design, manufacturing, and analysis of the 3D-printed sandwich-structured components which experienced various loadings and environmental conditions. The core structure plays a major role in the in-plane behavior of lattice composites, therefore in this study, sandwich specimens with two types of core topologies made of two common and similar 3D printing filaments, acrylonitrile butadiene styrene (ABS) and acrylonitrile styrene acrylate (ASA), were manufactured. Based on the applications of sandwich-structured parts, they might experience different temperatures in their service life. In order to determine effects of thermal environment, we conducted accelerated thermal aging within temperatures of 22-60 °C, which is below glass temperature of the examined materials. Based on a series of three-point bending tests, the failure behavior of the original and aged components are determined, and the effects of temperature change on the bending behavior of 3D-printed sandwich parts are discussed. The experimental practice revealed that ASA with honeycomb core specimens indicated highest stability under bending load after thermal aging. The current study sheds lights on durability of 3D-printed sandwich structural elements, and the obtained results demonstrate feasibility of 3D printing technology in fabrication of thermal-stable sandwich structures.

A review of research on the urban thermal environment effects of green quantity

The regulative function of green quantity in urban thermal environment is an important topic in urban studies. Here, we reviewed the concepts and developments of green quantity, the measurements of green quantity and urban thermal environment, the relevance between green quantity and urban thermal environment, and its implications for urban planning. After summarizing domestic and international research processes, we put forward four prospective directions: 1) improving the methods for three-dimensional investigation of green quantity, 2) developing means for urban thermal environment monitoring and forecasting, 3) establishing an index system for three-dimensional pattern of urban green quantity, and 4) creating three-dimensional analytical methods to quantify the relationship between green quantity and urban thermal environment. It was expected to provide a three-dimensional spatial perspective for exploring the relevance between green quantity and urban thermal environment. It was proposed to deeply examine three-dimensional patterns of urban green quantity, in order to balance urban thermal environment and multiple ecological benefits, and to provide scientific basis for urban green space planning and design, as well as to form theoretical supports for adaptation to climate change and regulation of urban thermal environments.

Effect of Temperature on Electromagnetic Performance of Active Phased Array Antenna

Active phased array antennas (APAAs) can suffer from the effects of harsh thermal environments, which are caused by the large quantity of power generated by densely packed T/R modules and external thermal impacts. The situation may be worse in the case of limited room and severe thermal loads, due to heat radiation and a low temperature sink. The temperature field of the antenna can be changed. Since large numbers of temperature-sensitive electronic components exist in T/R modules, excitation current output can be significantly affected and the electromagnetic performance of APAAs can be seriously degraded. However, due to a lack of quantitative analysis, it is difficult to directly estimate the effect of temperature on the electromagnetic performance of APAAs. Therefore, this study investigated the electromagnetic performance of APAAs as affected by two key factors—the uniformly distributed temperature field and the temperature gradient field—based on different antenna shapes and sizes, to provide theoretical guidance for their thermal design.

Genetic background and thermal environment differentially influence the ontogeny of immune components during early life in an ectothermic vertebrate.

An understudied aspect of vertebrate ecoimmunology has been the relative contributions of environmental factors (E), genetic background (G) and their interaction (G×E) in shaping immune development and function. Environmental temperature is known to affect many aspects of immune function and alterations in temperature regimes have been implicated in emergent disease outbreaks, making it a critical environmental factor to study in the context of immune phenotype determinants of wild animals. We assessed the relative influences of environmental temperature, genetic background and their interaction on first-year development of innate and adaptive immune defences of captive-born garter snakes Thamnophis elegans using a reciprocal transplant laboratory experiment. We used a full-factorial design with snakes from two divergent life-history ecotypes, which are known to differ in immune function in their native habitats, raised under conditions mimicking the natural thermal regime-that is, warmer and cooler-of each habitat. Genetic background (ecotype) and thermal regime influenced innate and adaptive immune parameters of snakes, but in an immune-component specific manner. We found some evidence of G×E interactions but no indication of adaptive plasticity with respect to thermal environment. At the individual level, the effects of thermal environment on resource allocation decisions varied between the fast- and the slow-paced life-history ecotypes. Under warmer conditions, which increased food consumption of individuals in both ecotypes, the former invested mostly in growth, whereas the latter invested more evenly between growth and immune development. Overall, immune parameters were highly flexible, but results suggest that other environmental factors are likely more important than temperature per se in driving the ecotype differences in immunity previously documented in the snakes under field conditions. Our results also add to the understanding of investment in immune development and growth during early postnatal life under different thermal environments. Our finding of immune-component specific patterns strongly cautions against oversimplification of the highly complex immune system in ecoimmunological studies. In conjunction, these results deepen our understanding of the degree of immunological flexibility wild animals present, information that is ever more vital in the context of rapid global environmental change.

Noise-adaptive test of quantum correlations with quasiprobability functions

We introduce a method for testing quantum correlations in terms of quasiprobability functions in the presence of noise. We analyze the effects of measurement imperfection and thermal environment on quantum correlations and show that their noise effects can be well encapsulated into the change of the order parameter of the generalized quasiprobability function. We then formulate a noise-adaptive entanglement witness in the form of a Bell-type inequality by using the generalized quasiprobability function. Remarkably, it allows us to observe quantum correlations under severe noise. Our method provides a useful tool to test quantum correlations in near-term noisy quantum processors with continuous-variable systems.

Effects of early thermal environment on the behavior and learning of a lizard with bimodal reproduction

Early developmental temperatures influence the physiology and behavior of reptiles, with important consequences for their fitness and survival. For example, many viviparous lizards are cold adapted which may restrict their activity times during the reproductive season, increasing their susceptibility to global warming. However, it is unclear if and how lizards with different reproductive modes (oviparity vs. viviparity) can respond to rising temperatures by modifying their life-history traits. We examined the effect of developmental temperatures on hatchling behavior and learning in viviparous and oviparous populations of the lizard Saiphos equalis to test whether their reproductive behavior can buffer against rising temperatures. Gravid females from both populations were subjected to current or projected end-of-century (future) thermal environments to evaluate differences in the exploratory, foraging and antipredator behavior, and spatial learning ability of their offspring. We found that viviparous lizards were more exploratory and had a less-pronounced antipredator response than oviparous lizards. Regardless of the mode of reproduction, elevated temperatures reduced the exploratory behavior of hatchling lizards. Elevated temperatures also reduced the foraging efficiency of oviparous, but not viviparous, hatchlings. Finally, future-gestated oviparous hatchlings were more likely to choose the correct refuge and made fewer mistakes in a spatial learning task; however, we found only weak evidence of spatial learning in S. equalis. Our results suggest that although global warming is likely to have a negative impact on phenotypic traits, in S. equalis, some of these effects may be ameliorated by maternal behavior and/or physiological responses during pregnancy, particularly in viviparous populations. Computational modeling studies suggest that live-bearing lizards (viviparous) are more vulnerable to global warming compared with egg-laying ones (oviparous). However, there is little experimental evidence showing that viviparous species are indeed at a greater risk of extinction. Using a lizard species that has both oviparous and viviparous populations, we tested the effect of high developmental temperatures (projected for 2100) on the behavior and learning of their offspring. We found that elevated temperatures had a stronger negative effect on egg-laying lizards by producing hatchlings with lower foraging efficiency. Our results suggest that viviparous mothers can ameliorate some of the effects of global warming on their offspring. Moreover, our study suggests that if live bearers are indeed more vulnerable to global warming, it is likely not due to maladaptive behavior in offspring, but rather, to other causes that affect pregnant females.

Thermal buckling of porous symmetric and non-symmetric sandwich plate with homogenous core and S-FGM face sheets resting on Pasternak foundation

The effect of porosity and thermal environment on buckling responses for the sandwich plates with different boundary conditions is analyzed and discussed in the present study. The author’s recently developed sandwich plate using a new modified sigmoid function based functionally graded material (S-FGM) plate of different symmetric and asymmetric configurations is considered. A new temperature distribution through the thickness based on modified sigmoid law is proposed in which temperature is assumed to be conducted in the thickness direction. Three different types of porosity are considered viz. even, uneven but symmetric and uneven but non-symmetric. A new uneven non-symmetric porosity model is used in which micro-voids are varied in accordance with material property variation in the thickness direction to capture the accurate distribution of voids on the plate. The principle of virtual work is employed to derive equilibrium equations. An exact solution is obtained using the assumed solution with shape functions satisfying the edge boundary conditions. This is implemented using Galerkin Vlasov’s method. The analysis has been performed to study the effect of porosity, geometric configurations, inhomogeneity parameter, and foundation parameter. It is observed that the elastic foundation parameters have the least effect on non-symmetric plate configuration subjected to nonlinear temperature distribution in comparison to other symmetric and non-symmetric plate configurations and temperature distribution. Besides, the non-symmetric plate configuration possesses maximum thermal buckling temperature in comparison to a symmetric configuration. The volume fraction exponent with value 2 is observed as a changeover point where the effect of porosity distribution is null and void for 2-1-1 plate configuration irrespective of boundary conditions. The calculated outcomes and interpretations can be useful as a validation study for the imminent investigation of sandwich S-FGM plates having porosities in the thermal environment.

Daily fluctuating temperatures decrease growth and reproduction rate of a lethal amphibian fungal pathogen in culture

BackgroundEmerging infectious diseases (EIDs) are contributing to species die-offs worldwide. We can better understand EIDs by using ecological approaches to study pathogen biology. For example, pathogens are exposed to variable temperatures across daily, seasonal, and annual scales. Exposure to temperature fluctuations may reduce pathogen growth and reproduction, which could affect pathogen virulence, transmission, and environmental persistence with implications for disease. We examined the effect of a variable thermal environment on reproductive life history traits of the fungal pathogen Batrachochytrium dendrobatidis (Bd). Bd causes chytridiomycosis, an emerging infectious disease of amphibians. As a pathogen of ectothermic hosts, Bd can be exposed to large temperature fluctuations in nature. To determine the effect of fluctuating temperatures on Bd growth and reproduction, we collected temperature data from breeding pools of the Yosemite toad (Anaxyrus canorus), a federally threatened species that is susceptible to chytridiomycosis. We cultured Bd under a daily fluctuating temperature regime that simulated Yosemite toad breeding pool temperatures and measured Bd growth, reproduction, fecundity, and viability.ResultsWe observed decreased Bd growth and reproduction in a diurnally fluctuating thermal environment as compared to cultures grown at constant temperatures within the optimal Bd thermal range. We also found that Bd exhibits temperature-induced trade-offs under constant low and constant high temperature conditions.ConclusionsOur results provide novel insights on variable responses of Bd to dynamic thermal conditions and highlight the importance of incorporating realistic temperature fluctuations into investigations of pathogen ecology and EIDs.