Changes In Ambient Temperature Research Articles

Improved photoresponse performance of self-powered solar-blind UV photodetectors based on n-Si/n-Ga2O3/p-Li:NiO dual-junction

The solar-blind photodetectors (SBPDs) based on the wide-bandgap semiconductor gallium oxide (Ga2O3) exhibit significant potential for applications in military, civilian, and medical fields. Although multiple structural designs of Ga2O3-based SBPDs have been proposed, their performance typically falls short of commercial standards. However, the photoresponse speed of most self-powered PDs decreases rapidly in the solar-blind region. To address this issue, we first prepared high-quality single-crystal β-Ga2O3 films using RF magnetron sputtering, which exhibit an average transmittance exceeding 85% across the 400–800 nm range and possess a relatively smooth surface. Subsequently, a superior performance self-powered SBPD of vertical structure of n-Si/n-Ga2O3/p-Li:NiO dual-junction was fabricated, which possesses a responsivity of 0.18 mA/W, a photo-to-dark current ratio of 395, rapid rise/decay times of 132/148 ms, and a specific detectivity of 1.57 × 109 Jones at 0 V bias under 254 nm illumination. The photocurrent of the device fully recovered to its initial level after experiencing changes in ambient temperature [from room temperature (RT) to 100 °C and back to RT], demonstrating robust stability in harsh environments. In addition, the valence band structures of p-Li:NiO and n-Ga2O3 were investigated in detail using XPS, and the working mechanism of the devices was analyzed based on the Fermi level alignment. The excellent performance of PDs can be attributed to the increased depletion layer width, which generates more photogenerated carriers. Additionally, the separation and transmission of photo-induced carriers are enhanced by the superposition of a double built-in electric field. Our strategy offers a promising approach for achieving high-performance Ga2O3-based photovoltaic PDs.

Performance analysis and optimization of a combined cooling, heating and power system based on active regulation of thermal energy storage

The energy storage unit can significantly address the issue of mismatch between the energy supply and demand of the combined cooling, heating and power (CCHP) system. Therefore, this article proposes a micro-gas turbine coupled with low-concentrating photovoltaic/thermal CCHP system with thermal energy storage active regulation, which can change the thermoelectric output ratio of the micro-gas turbine. The impact of the volume of the heat storage tank and the changes in ambient temperature on the system's performance is analyzed. This system is optimized with the objective functions of primary energy consumption saving rate, carbon dioxide emission reduction rate, total annual cost saving rate and exergy efficiency maximization. The results indicate that increasing the volume of the thermal energy storage tank enhances the exergy efficiency. Furthermore, an increase in ambient temperature can improve the objective functions. The optimum comprehensive performance of this system is achieved when the thermal energy storage tank volume is 40 m³ and the gas boiler capacity is 241.16 kW. With the thermal energy storage active regulation, the primary energy consumption, carbon dioxide emissions and annual total cost of the system decline by 2.51%, 2.37% and 1.22%, and the system exergy efficiency improves by 1.98%.

Design optimization of continuous fiber composites with thermo-mechanical coupling and load uncertainties

This paper introduces a theoretical framework for the design optimization of continuous fiber composites reinforced with continuous fiber trajectories subject to thermo-mechanical coupling and load uncertainties. Different uniform temperature variations are applied in the structure to investigate the influence of ambient temperature change on the structural performance. To consider the external load uncertainties, a robust design optimization model is proposed where the loads are modeled as hybrid variables, namely magnitudes as random variables and directions as interval variables, with the robust objective determined through a hybrid orthogonal polynomial expansion method. Furthermore, we use a level-set function to represent the structural boundary, with its evolution driven by shape derivatives calculated based on uncertainty analysis. The continuous fiber paths are subsequently determined by the level-set isoline extracted from the structural boundary, which in turn influences the structural mechanical performance due to the material anisotropy of composites. The continuity of continuous fiber and the equal space between adjacent trajectories largely ensure the additive manufacturability of the composites. Three numerical examples are presented to demonstrate the effectiveness of the developed framework. The results show that the ambient temperature variations and load uncertainties largely impact the optimized topology and fiber infill patterns of composites, thus are important to be considered in the design stage. Moreover, the optimized structure can have a 5-fold stiffness per unit mass compared with the initial design thus largely increasing the material efficiency in carrying external uncertain loads.

A highly visible-transparent thermochromic smart window with broadband infrared modulation for all-season energy savings

Abstract Thermochromic smart windows effectively reduce the energy consumption for building through passive light modulation including the transmission of visible (TVis), near-infrared (TNIR), and the emissivity of mid-infrared (εMIR) in response to the ambient temperature change. However, thermochromic windows that maintain high TVis while modulating TNIR and εMIR simultaneously are highly desirable but still challenging. Here, we develop a thermochromic smart window based on a two-way shape memory polymer to enable reversible transformation and achieve TNIR modulation of 44.0% and εMIR modulation of 76.5% while maintaining high TVis (>50%). Compared to traditional windows based on silica glass, this device shows 4°C lower temperature in summer daytime, 2°C higher in winter daytime, and 1°C higher in spring nighttime. It is expected that our device can achieve greater annual energy savings in comparison with commercial glass anywhere in the world and promote the progress of thermochromic windows for energy-efficient buildings.

The effect of different mission profiles and ambient temperature on the lifetime of boost converter IGBT with a robust controller in a hybrid electric vehicle

AbstractThe reliability of power electronic converters is one of the essential issues in designing of electric vehicles. This paper estimates the lifetime of the boost converter switch by Semikron and Coffin‐Manson models for two common failure mechanisms of Bond wire and Base plate solder, respectively. Four mission profiles based on the Artemis standard are applied to hybrid electrical vehicle model to determine unidirectional output power. Kharitonov's theory is used to design a robust controller to handle the uncertainty raised by different power cycles of the electric vehicle and the parameters of the converter during simulation. Stability of converter is achieved during simulation by identifying simple proportional integral controller coefficients with Kharitonov's theorem. A prototype 230 W boost converter is designed and utilized to validate average model and switch loss calculation relationships. The lifetime results indicate that the number of cycles, and the average and the maximum junction temperature have a more impact than the duration of the drive cycle on the lifetime of the converter. A mixed mission profile is considered to investigate the effect of sudden change in driving modes and speed on total consumed life and lifetime to enhance the study's applicability. Lifetime of switch is decreased significantly in mixed mode in comparison with other mission profiles in the same driving time. Furthermore, the motorway mission profile has 53%, 39.6%, and 160% less total consumed life in comparison with the urban, rural and mixed mission profiles, respectively. In addition, the effect of ambient temperature changes on IGBT lifetime has been investigated for four mission profiles. While motorway had the least total consumed life in 25°C, the urban had better performance in comparison with other mission profiles from 25 to 55°C.

How ambient temperature rise affects mercury dynamics and its pools in secondary forests

The forest ecosystem is a significant pool for capturing atmospheric mercury (Hg) deposition, with most Hg accumulating in forest soils. As secondary forests now dominate global forest cover, they are particularly sensitive to changes in ambient temperature. However, the impact of these changes on Hg dynamics in secondary forests remains poorly understood. Here, we quantified Hg inputs, outputs, and mass balances in two secondary forests in China, each with different ambient temperatures. We found that elevated ambient temperature (~1.0℃) advanced the germination of leaves by 2-3 days and extended the growing season by approximately one week, resulting in increased litterfall biomass by 1.18 Mg hm-2 yr-1 and a thicker litterfall layer by 0.22cm over 34 years. This temperature rise also facilitated Hg methylation within forest and enhanced methylmercury (MeHg) export, heightening the potential risk of MeHg exposure to surrounding ecosystems. Additionally, higher ambient temperature not only increased soil Hg emissions (2.75µgm-2 yr-1) but also led to significant Hg deposition via litterfall (9.26µgm-2 yr-1), resulting in a net annual Hg deposition of 6.88µgm-2 yr-1. This net Hg deposition accumulated in the topsoil, increasing the Hg pool by 0.51mgm-2 in organic and 0-10cm mineral soil horizons. Our findings suggest that even a ~1.0℃ temperature rise could enhance the role of secondary forests as atmospheric Hg sink by 45.10%. Therefore, the impact of ongoing climate warming on Hg cycling and pools in forests should receive increased attention and warrants further research.

High capacity, low power, short reach integrated silicon photonic interconnects

The architecture and component technology of a low power, high capacity, short reach optical interconnect are detailed. Measurements from high-performance 300 mm silicon photonics components that comprise the system are shown, along with a quantum-dot mode-locked laser 20-channel comb source with free space wall plug efficiencies up to 17%, advanced packaging techniques for 3D silicon photonic-electronic integration, and schematics for integrated electronics that control the photonic integrated circuits. Techniques for operating such a system in the presence of changing ambient temperature are addressed. Experiments on a 1 Tbps design are conducted with an optical link experiment indicating sub-picojoule/bit energy consumption at scale.

Studying the effect of ambient temperature variations on perovskite precursor film formation using different antisolvents

This study investigates the sensitivity of two antisolvents to ambient temperature fluctuations during the fabrication of triple-cation perovskite thin films. Chlorobenzene (CB) and ethyl acetate (EA) were employed as antisolvents in the preparation of perovskite solar cells (PSCs) under identical ambient temperature variation conditions. The experimental results reveal that the quality of the perovskite films does not exhibit a consistent trend in response to ambient temperature changes depending on the antisolvent used. When CB was used as the antisolvent, the highest-performing device, produced at an ambient temperature of 18 °C, achieved a power conversion efficiency (PCE) of 19.9 %. In contrast, when EA was employed as the antisolvent, the highest-performing device was fabricated at 25 °C, reaching a PCE of 20.5 %. Furthermore, when the ambient temperature exceeded 30 °C, all films prepared with either antisolvent exhibited significant cracking, indicating that elevated temperatures adversely affect perovskite film formation. To further investigate the mechanism through which ambient temperature affects the film-forming process, antisolvents at varying temperatures were used during perovskite film preparation to simulate transient temperature increases during formation. This study reveals that the impact of ambient temperature variations on perovskite film formation does not exhibit a uniform trend but is significantly influenced by the choice of antisolvent. Moreover, this work offers valuable insights for optimizing the fabrication of high-quality perovskite thin films.

Adaptive temperature compensation for [formula omitted] humidity sensor in complex environments using ISSA-BP neural network

High-precision humidity detection in complex environments is essential across various fields. In this study, a high-performance MoS2 humidity sensor with a dynamic response time of less than 3 s was developed using molten salt-assisted chemical vapor deposition. To address the challenges posed by dynamic ambient temperature changes on sensor accuracy, an improved sparrow search algorithm-back propagation (ISSA-BP) neural network was constructed to mitigate temperature drift and correct nonlinear errors in the sensor output. The ISSA-BP neural network utilizes a global optimization strategy with adaptive learning, significantly enhancing accuracy and efficiency by optimizing the initialization and iterative update processes of traditional algorithms. Experimental results indicate that the proposed ISSA-BP achieves an average relative error of just 0.75% in humidity sensors across various environmental conditions, representing a 5.8-fold improvement in accuracy compared to traditional methods. Additionally, the algorithm demonstrated high robustness and accuracy across different environments, sensors, and datasets, confirming its applicability in complex and variable scenarios.

Dual-Mode cellulose acetate@Al2O3/MWCNTs Janus fabric with radiative cooling and solar heating for personal thermal management

Personal thermal management (PTM) textiles with heating and cooling functionalities are highly appealing due to their potential to offer personalized comfort while also contributing to decrease energy consumption. However, most PTM fabrics are static and unable to meet the human body’s thermal comfort needs during seasonal and ambient temperature fluctuations. Herein, this work presents a dual-mode Janus Metafabric to provide radiation cooling and solar heating. The cooling side of Metafabric (cellulose acetate@Al2O3 porous coating) offers high solar reflectance (92.12 %), infrared emissivity (83.22 %), and net cooling power of 55.85 W·m−2. The heating side (multi-walled carbon nanotubes) exhibits a high solar absorption rate (88.4 %). Compared with raw fabric, it can achieve an additional cooling of 4.58 °C and heating of 38.02 °C. In addition, Metafabric also have excellent ultraviolet resistance, wear resistance, and washing properties, making it suitable for practical wearing. By flipping the Janus fabric, it is easy to switch between the cooling and heating modes to adapt to dynamic ambient temperature changes, which have great potential for maintaining human thermal comfort and alleviating the energy crisis.

Bioinspired smart dual-layer hydrogels system with synchronous solar and thermal radiation modulation for energy-saving all-season temperature regulation

All-season thermal management with zero energy consumption and emissions is more crucial to global decarbonization over traditional energy-intensive cooling/heating systems. However, the static single thermal management for cooling or heating fails to self-regulate the temperature in dynamic seasonal temperature condition. Herein, inspired by the dual-temperature regulation function of the fur color changes on the backs and abdomens of penguins, a smart thermal management composite hydrogel (PNA@H-PM Gel) system was subtly created though an “on-demand” dual-layer structure design strategy. The PNA@H-PM Gel system features synchronous solar and thermal radiation modulation as well as tunable phase transition temperatures to meet the variable seasonal thermal requirements and energy-saving demands via self-adaptive radiative cooling and solar heating regulation. Furthermore, this system demonstrates superb modulations of both the solar reflectance (ΔR = 0.74) and thermal emissivity (ΔE = 0.52) in response to ambient temperature changes, highlighting efficient temperature regulation with average radiative cooling and solar heating effects of 9.6 °C in summer and 6.1 °C in winter, respectively. Moreover, compared to standard building baselines, the PNA@H-PM Gel presents a more substantial energy-saving cooling/heating potentials for energy-efficient buildings across various regions and climates. This novel solution, inspired by penguins in the real world, will offer a fresh approach for producing intelligent, energy-saving thermal management materials, and serve for temperature regulation under dynamic climate conditions and even throughout all seasons.

Modeling of Bacillus cereus evolution in pasteurized cow milk locally distributed at point of sale: a case of three companies in Tlemcen region, Algeria

Bacillus cereus is among the most hazardous bacteria that could reduce the shelf life of pasteurized milk and could threaten consumers’ health. These bacteria groups are known for their heat resistance and their ability to produce two types of toxins, diarrheic and emetic. This study aimed to enumerate the B. cereus in raw cow’s milk collected from three companies in the Tlemcen region, then modeled, based on a probabilistic approach, their evolution throughout the process, split into six steps, until the point of sale. At first, the analysis of 242 samples on MYP medium, shows a high prevalence between 92% and 98% of B. cereus with variable concentrations among the three companies. Throughout the storage of milk at refrigeration temperatures (2°C, 4°C and 5°C), no growth of B. cereus was estimated. Otherwise, the pasteurization process reduces the contamination level depending on pasteurization temperature as for company A, the mean concentration decreases from 1.53 log CFU/mL to 1.07 log CFU/mL. In this study, the distribution step at ambient temperature changes significantly the B. cereus concentration to reach a critical concentration during July and August. In conclusion, the quality of raw cow milk must be controlled before reception on the farm and the cold chain must be maintained throughout all process points until consumption.

Effects of thermal cycles and time-dependent behavior of the deck on steel network arch bridges

Network arches are a type of arch bridges with inclined hangers, in which some hangers cross each other at least twice. This paper aims to evaluate the effects of thermal fluctuations and volumetric changes of the concrete deck on steel network arches. Fifty-nine variants of a reference network arch bridge were developed, assuming identical arch geometries but varying hanger arrangements. Each bridge was modeled using the finite element method and subjected to heat flux due to solar radiation and changes in ambient temperature in addition to heat transfer via conduction, convection, and radiation. The time-dependent deformations of the concrete deck were implemented using a rate-type formulation. Results obtained during a one-year period after the assumed end of construction showed that stress changes in the arch bridge due to ambient and time-dependent effects were not very sensitive to the hanger layout. Neglecting concrete creep and shrinkage was found to cause a 15-20% underestimation of maximum stresses in the concrete deck, whereas a 40-60% error was observed in both the deck and rib when thermal effects were ignored. The radial arrangement of hangers, already known to perform favorably under live loads, was also found to provide the smallest bending moments and the fewest number of relaxed hangers due to thermal and time-dependent effects.

The growth mechanism and optical properties of flower-like porous Gd2O2S:Er3+/Yb3+ phosphor

The self-assembly mechanism of porous materials has always been a hot topic and a challenging issue in research. What factors induce the self-assembly process, and how is the temperature sensing performance related to it? Innovatively, in this paper, Gd2O2S:Er3+/Yb3+ phosphors with different morphologies were synthesized, and elucidated the formation mechanism of flower-like structures through relevant theorems, formulas, and experiments, proposing that polar molecules and dipole-dipole interactions guide the synergistic effect of van der Waals forces and hydrogen bonding, which ultimately induces the self-assembly of spherical structures into flower-like ones. In addition, four representative intermediates were selected to investigate their luminescence and temperature sensing properties. The results show that the flower-like sample can respond more effectively to changes in ambient temperature because of its rich pore structures, and thus exhibit better temperature sensing performance. In-depth research on the self-assembly mechanism of materials helps to predict and regulate their properties, and the unique characteristics of flower-like sample provide new ideas for material selection in the field of high-precision temperature measurement.

Global climate change impacts on the potential distribution of typical Trachinotus fishes and early warning assessment of invasions

Marine habitats and ecosystems are increasingly being impacted by global climate change and the global spread of captive breeding. In this study, we focused on five typical Trachinotus species (Trachinotus anak, Trachinotus blochii, Trachinotus mookalee, Trachinotus goreenisi, Trachinotus ovatus) as research subjects. We utilized species distribution models and ecological niche models to predict the present and future potential distribution of these species, as well as to assess ecological niche overlap and evaluate the early warning of invasion by Trachinotus species. T. ovatus stands out with its broad distribution range and high adaptability to different environments. It occupies 1.114% of medium-high suitable areas, spanning 100,147 km2. Our predictions also suggest that T. ovatus would undergo a significant expansion (approximately 55% of the total area) under both past and future environmental scenarios, demonstrating a higher tolerance and adaptability to changes in ambient temperatures. It can be discerned that T. ovatus exhibits strong environmental adaptability, which may potentially lead to biological invasion along the southeastern coast of China. The T. anak, on the other hand, showed a higher expansion trend under high carbon dioxide concentrations (RCP8.5), indicating a certain convergence with carbon dioxide concentration. Our models showed that under future climatic conditions, T. ovatus would become the dominant species, with increased competition with T. mookalee and decreased competition with T. goreenisi, T. mookalee, and T. anak. Based on our findings and the net-pen culture mode of T. ovatus, we identified the hotspot habitat of T. ovatus to be located in the Indo-Pacific convergence zone. However, there is a possibility of an expansion trend towards the southeast coast of China in the future. Therefore, it is crucial to provide an early warning for the potential biological invasion of T. ovatus.

Preferences for drinking water temperature in mice vary with ambient temperature.

Temperature detection and temperature preference are critical for the maintenance of thermal homeostasis and protection from noxious temperature. Methods to measure the time spent on plates of different temperatures such as the two-plate test and thermal-gradient test are generally used to evaluate temperature preference. In this study, we established a temperature preference test that assesses water drinking behavior by modifying the two-bottle taste preference test. We found that mice in a common-temperature environment of 23 °C avoid drinking water more than 40 °C. While mice in a common-temperature environment preferred 10 °C and 30 °C water equally, mice in a hot environment at 35 °C preferred to 10 °C water compared to 30 °C water. Moreover, mice in a cold environment of 10 °C did not avoid drinking 40 °C water compared to 10 °C water. From these results, the temperature preference test that we developed could be used to evaluate temperature preference owing to the ambient temperature changes.

Energy consumption analysis and operating characteristics research on small time scale of variable refrigerant flow air conditioning systems in public buildings

In order to analyze the energy consumption and operation characteristics of the variable refrigerant flow (VRF) air-conditioning system on small time scale and put forward effective energy-saving suggestions, the VRF system operation experiments are carried out under different indoor set temperatures, different indoor unit opening quantities and different indoor set air velocities. This experiment studies the main influencing factors of energy consumption and operation of the VRF system, such as indoor temperature difference, indoor air velocity, outdoor environment temperature and so on. The results show that the rated power of indoor unit is linearly related to the energy consumption of the VRF system. The total active power changes greatly when the VRF starts and stops, and the outdoor ambient temperature changes. The indoor set air velocities have a great influence on the energy consumption and operation of the VRF system. The performance parameters increase first and then decrease with the increase of compressor frequency and load rate. When the load rate is 40 %∼60 %, the performance parameters can reach 3.2 ∼ 4.2.

What is the relationship between risk attitudes and ambient temperature? Evidence from a large population-based cohort study

Rising temperatures affect human behavior and risk-taking in several domains. However, it is not yet well understood just how ambient temperature shapes risk attitudes. Using data from the large population-based KORA-Fit study (Cooperative Health Research in the Region of Augsburg) of older people (N=2454), we identify a statistically significant, but very small, positive association between short-term ambient temperature changes and individuals’ general willingness to take risks. Health-related risk attitudes, however, show no significant relationship with temperature. These findings support a domain-specific view of risk attitudes, with results remaining consistent for vulnerable individuals with the chronic conditions diabetes, hypertension, and asthma. Overall, our findings suggest that risk attitudes are somewhat stable towards changes in ambient temperature.

The Thermal Performance of The Plate-fin Heat Sink under Natural Convection at Different Power Levels and Ambient Temperatures

The thermal performance of a flat heat sink and a plate-fin heat sink was experimentally compared under natural convection conditions at thermal powers of 16.5 W and 33 W and ambient temperatures of 30°C and 40°C. For the same heating powers, surface and junction temperatures increased as the ambient temperature rose from 30°C to 40°C, but the increase was not as much as the ambient temperature change. For the flat heat sink, the increase in junction temperature was 5°C at 16.5 W and 6.68°C at 33 W. For the plate-fin heat sink, the increase in junction temperature was 3.55°C at 16.5 W and 4.47°C at 33 W. The increase in surface temperature for the flat heat sink was 5.35°C at 16.5 W and 5.91°C at 33 W, while for the plate-fin heat sink, the surface temperature increase was 4.76°C at 16.5 W and 2.22°C at 33 W. The thermal resistance of the flat heat sink was around 4 K/W, while for the plate-fin heat sink, it ranged between 2-2.5 K/W, providing approximately twice the advantage in thermal resistance for the plate-fin model compared to the flat model. Under all conditions, the Rayleigh number (Ra) significantly decreased with the increase in ambient temperature but increased with the applied thermal power. Thus, the increase in Rayleigh number with power was more pronounced in the plate-fin model, indicating a more significant effect. In the plate-fin model, the fin efficiency slightly decreased with the increase in ambient temperature, from 0.63 to 0.62 at 16.5 W and from 0.65 to 0.64 at 33 W.

Enhanced Peltier refrigerator using an innovative hot-side heat-rejection mechanism; Experimental study under both transient and steady-state conditions

Peltier refrigerators are an environmentally friendly cooling method, as they require no refrigerants and have no moving parts. However, effective cooling requires optimal-strong heat rejection from the hot side of the Peltier module. This research proposes and tests a self-capillary ultra-thin (0.1 mm) water-attracting coated PVC membrane (SCCP) as an innovative effective heat rejection mechanism. The SCCP cools the hot side of the Peltier module to temperatures even lower than ambient air, without external power. The cooling effect is achieved through the evaporation of a thin water film on the hot surface, driven by capillary action, which releases latent heat. This process can occur under natural or forced convection, both of which are investigated under various voltage and temperature conditions. The SCCP method was compared to traditional heatsinks and showed superior performance, with the hot side temperature being not only cooler than that in heatsink mode but also cooler than the ambient temperature in most cases. Additionally, the SCCP method demonstrated reduced sensitivity to ambient temperature changes, with only a 2–3° increase in the hot side temperature when the ambient temperature was raised by 10°. The findings suggest that SCCP is a promising technique, with further results discussed.