Search

Several mechanochemically heated processes have been published in recent years. However, precise control over the mechanochemical catalysed coupling reactions remained elusive. A recent report from Leitch, Browne and co‐workers demonstrated how a programmable jar heater manifold delivers an efficient methodology for the Suzuki–Miyaura‐type cross coupling reaction of aryl sulfamates and aryl boronic acid species. This methodology can be readily upscaled 200‐fold using twin‐screw extrusion methodologies. [ABSTRACT FROM AUTHOR]

Temperatures predicted by the Thermal Mathematical Models (TMMs) used in the thermal control design of spacecraft, usually present differences with the values measured during the thermal test campaign. Therefore, the TMMs must be correlated with the thermal tests to reduce these differences to admissible values. This task can be addressed in an automatized way considering the correlation as an optimization problem, where the differences between predicted and measured temperatures are minimized. This is achieved modifying the values assigned to some parameters used in the TMMs. The main drawback of this approximation is the risk of loosing the physical sense of some model parameters. The reason is that the thermal inverse problem, that is, calculate the thermal parameters that produce a specific temperature distribution, often has not a unique solution. A methodology of automatized correlation to calculate the correct values of the model parameters, in the sense that they maintain its physical interpretation, is presented in this article. The key point relies in setting up an overdetermined system of equations. The expression to calculate the minimum number of load cases required, is developed, and several case studies are presented to validate the proposed methodology. A gradient based public available set of subroutines (TOLMIN) has been used as optimization algorithm. • Application of a temperatures correlation method to a real experiment flown in the ISS. • Development of minimization software for space thermal tests. • Suggested guidelines for future thermal balance experiments. • In depth analysis of algorithm results and their applicability. [ABSTRACT FROM AUTHOR]

• A 3D printer is designed for on-orbit servicing/manufacturing missions. • A thermal control strategy that uses P and fuzzy PI controllers is designed. • The PEEK material is selected to study the thermal control performances. • The simulation results show that the 3D printer is feasible to work on-orbit. On-orbit manufacturing can reduce the cost and time needed by space exploration missions because in-situ maintenance activities can be achieved without the need for additional launches. Furthermore, recent developments in materials science in terms of better mechanical and thermal performance have allowed this application to become a potential reality. However, the deployment of on-orbit manufacturing presents several challenges, including the lack of convective heat transfer and human intervention. This paper proposes an on-orbit 3D printing device capable of operating at a temperature up to 400 °C in the vacuum environment. To validate its feasibility for on-orbit manufacturing, we designed four extruders with different characteristics. We investigated the temperature profiles across the extruders under the vacuum condition through a heat transfer model. Based on the thermal analysis, a thermal control method, which combines the Proportion (P) and Fuzzy Proportion and Integration (Fuzzy PI) strategies, is designed to regulate the 3D printing device operation. With the extrusion rate of 8654.6 mm3 /h and the printing temperature at 400 °C, the melting and solidification status of the PEEK (Polyether ether ketone) material is verified. [ABSTRACT FROM AUTHOR]

The unbalanced operation of multiphase drives has been adopted for the fault-tolerance purpose in mission critical applications. However, the higher number of phases increases the number of devices and the probability of thermal mismatches among them. Indeed, parametric mismatches, thermal cross coupling, inhomogeneous cooling, and uneven degradation have been reported as root causes of critical thermal deviation among power semiconductor devices. Consequently, a higher temperature in a subset of devices provokes degradation unevenness and a lifetime reduction of the whole power converter. In modular systems, for example, power routing has been proposed to better distribute the temperature among the high number of devices and overcome this problem. Although not modular, the capability of a multiphase machine to operate under unbalanced condition allows an uneven power distribution without overloading the phases and degrading the machine magnetic performance. Therefore, this work investigates the soft-unbalance operation for power routing in multiphase drives. To validate the presented solutions, finite-element analysis based in a real multiphase system is conducted. Additionally, experimental results show the multiphase machine performance in soft-unbalanced conditions. Moreover, a case study is carried out to evaluate the impact of the power routing on the lifetime of a high power mission critical application. [ABSTRACT FROM AUTHOR]

This article presents a thermal control design method for a surface acoustic wave (SAW) device. We designed a heat-dissipation structure and packaging scheme to solve three key issues observed in SAW devices using anisotropic crystals as piezoelectric substrates in acoustofluidics (e.g., lithium niobate): SAW chip cracking caused by thermal stress, SAW chip cracking caused by mismatched thermal expansion coefficients of the packaging materials, and enhancement of the structural strength and stability of the SAW chip. This study establishes the physical model of the designed structure and the relationship between the steady-state working temperature and the physical properties of the material. By comparing these physical properties and numerical calculations, we identified nanosilver adhesive as the most effective bonding material between the SAW chip and the heat sink. In addition to designing and fabricating, we also evaluated our SAW devices experimentally. The results not only confirmed that the abovementioned three key problems were solved but also demonstrated the significant enhancement of the stability of the SAW device. [ABSTRACT FROM AUTHOR]

The precise calculation of GRACE and GRACE-FO satellite orbits is reliant on knowledge of accurate non-gravitational accelerations acting on the spacecraft. These are measured by the on-board accelerometers that require a thermal environment stabilised to ∼ ± 0.1 °C per revolution. However, during periods of the GRACE mission with reduced thermal control, internal temperature variations reached up to 10 °C within a revolution, causing low-frequency and non-linear drifts in the accelerometer observations. Additionally, accelerometer bias drifts occurred throughout the GRACE mission as changes in the orientation of the orbital plane with respect to the Earth-to-Sun vector caused the satellites to absorb more or less solar energy. These temperature-induced drifts degrade the quality of mass change estimates, particularly during the latter half of the GRACE mission after thermal control of the satellites was terminated. We filter (in the frequency domain) the accelerometer observations to remove these low-frequency components (f < 0.045 mHz). The bias drift removed from the cross-track is then scaled to derive a thermally-based correction for the highly sensitive along-track observations. We then estimate temporal gravity fields using the ANU GRACE software, our filtered accelerometer observations and the range acceleration as the inter-satellite observation. The use of our thermally-corrected accelerometer measurements significantly improves the accuracy of both orbit modelling and gravity field estimation. [ABSTRACT FROM AUTHOR]

Thermal deformation of space-borne radar antenna caused by dramatic changes in orbit thermal environment has a serious effect on image qualities. In this paper, the NX TMG module was used to simulate the orbit thermal environment of the antenna, and a thermal control design was proposed. The thermal control structure consists of three layers; the top is a radiator with high emissivity surface, the middle is a multi-layer insulation, and the bottom is a highly reflective layer. The simulation results show that the thermal design could reduce the temperature gradient from 238.1 to 31.4 °C effectively. [ABSTRACT FROM AUTHOR]

ABSTRACT Pesticide environmental risks and increased weed resistance have encouraged studies for alternatives to herbicides. Among these are weed thermal control methods by controlled heat application machines. Thus, this study aimed to test a prototype of heat-applicator machine as a function of changes in gas pressure, travel speed, and tire traffic effect on plants. Then, three experimental factors were tested: gas pressure (98, 196, and 245 kPa), travel speed (0.56, 0.78, and 1.17 m s−1), and tire traffic effect on plants (with and without traffic). The results showed that tire traffic effect on plants and subsequent heat application had no effect on control rate. Weed control rates reached levels considered satisfactory using a heat application speed of 0.56 m s−1 associated with gas pressures of 245 or 196 kPa, as well as a heat application speed of 0.78 m s−1 associated with a gas pressure of 245 kPa. A total between 60.9 and 84.9 kg ha−1 liquefied petroleum gas was required for weed control of around 80%.

The relevance of the study is caused by the lack of regulatory documents for the control of the rock mass in the conditions of its artificial freezing, unified requirements for organization and monitoring of the frozen wall formation. The main aim of the work is to substantiate the optimal technological parameters of the thermal control of the frozen wall. Objects of the research are the rock mass under the conditions of artificial freezing and the freezing system. Methods: experimental study of the temperature dynamics of the frozen rocks, statistical processing and analysis of experimental data; simulation of thermodynamic processes occurring in artificially frozen rock mass. Results. The paper presents the experimental measurements of temperature distribution in control wells in artificially frozen rock mass. The artificial freezing is considered in relation to the problem of mine shaft sinking in flooded rocks. Processing and analysis of experimental data shown the influence of the artificial freezing on local sections of the rock mass. A study was made of the influence of the control well location on the accuracy of the solution of the inverse Stefan problem. It makes possible to adjust the thermophysical properties of the rock mass model and calculate the temperature field in the entire volume of the frozen rock mass. It was determined that the control well should be placed straight between the adjacent freezing wells. The analysis of the emergency failures of the freezing wells showed that the required number of control wells should be at least 30 % of the total number of freezing wells. Performed thermal monitoring allows the substantiation of optimal locations and number of control wells with the necessary spatial resolution of temperature measurements of rock mass in depth. According to the results of the work, a methodology for selecting technological parameters of the method of frozen wall thermal control were proposed.

High-current pulsed electron beam sources are the core components of high-power microwave systems. In order to meet the requirements of future applications, one needs to improve the performance of electron beam sources in terms of vacuum insulation, beam transportation, and thermal management. In this paper, we report about our recent progress in the development of high-current vacuum electron beam sources. In order to meet the vacuum maintenance requirements of high-power microwave tubes, a high-electric field ceramic vacuum interface is designed and fabricated based on the ceramic metal brazing technique. In our experiments, a stable operation of the ceramic vacuum interface is demonstrated in the 10 Hz repetition mode with withstand voltage of larger than 600 kV and pulse width of about 100 ns. Besides, a cold cathode is developed using SiC nanowires, and an average beam current density of 1.2 kA/cm2 is achieved under the electric field strength of 90 kV/cm. Compared with traditional velvet cathodes, the characteristics of the SiC nanowire cathode, such as macro-electrical stability, emission uniformity, and operating life have been significantly improved. Furthermore, a high-current electron beam collector has been developed for relativistic backward wave oscillator tubes. A spiral flume is designed in the collector to meet the requirement of both high specific energy and low flow rate. It shows that the withstand heat flow density is in the order of 1012 W/m2, which is suitable for the long pulse and repetitive operation of the system. These results represent a significant step towards the practical application of long-life high-power microwave systems.

Satellite performance and capability have increased dramatically, particularly for micro- and nanosatellites, requiring more power supply and higher thermal conditions. Problems worth considering include how to provide more power with little or no weight increase, and how to reduce satellite thermal control difficulties. A new way to decrease the temperature of the solar panels on a satellite was proposed. Firstly, the model of solar cells is presented, and the relationship between solar irradiation and the electricity generated explained. Based on this, a new method to reduce the temperature of the solar cell is proposed. Details about current generation and temperature rise calculations for various types of solar cells are also provided. Finally, an experiment was conducted on original and proposed solar cells. While the experiment showed some degree of effectiveness, further experiments are needed.

The paper presents the findings of the investigative study on the contact zone of the tractive and carrying belts of the intermediate belt conveyor drive in cross section using thermal filming. The description of the test bench, conditions and sequence of the study is provided. The regularities of belt interaction are identified; particularly the irregularity of their adhesion in width in the contact zone, resulting in a number of primary longitudinally oriented areas. The location of the areas in cross section corresponds to the contact points of the belt sections with the roller ribs of supporting roller carriages. On the basis of the investigative study, the design procedure of the reduced factor of belt adhesion is developed. The procedure takes into account lumpiness of the loads as well, particularly probable bearing of the load particle layer adjacent to the belt directly through the edges. The paper shows the limitations within the context of the proposed procedure depending on the types of transported materials. The example of traction coefficient calculation is shown.

Two-phase cooling devices are used to remove and dissipate heat from high power-density electronic systems to maintain them within their operating temperature limits. The manufacture of these devices, such as heat pipes, thermosyphons or vapour chambers, involves firstly removing any internal air or non-condensable gases before charging with the required volume of working fluid. This paper presents detailed designs and operating instructions for a single bench-top station for use in a laboratory environment for the vacuum evacuation, degassing and charging of these devices. Two configurations allow for the filling of fluids which are either liquids or gases at standard temperature and pressure conditions. For liquids, the dispensed volume can be measured directly on an integrated burette, while the method of vapour transfer is used for gases. The hardware was demonstrated by filling multiple thermosyphon devices with a number of common working fluids used in two-phase systems, including water, acetone and ammonia. It was shown to deliver precise and repeatable filling volumes with average differences compared to target volumes of 1.7% and 10.5% for liquids and gases respectively. The design is intended to be highly customisable where its size can be modified to accommodate filling volume requirements for different applications., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2024 The Author(s).)

Ground thermal tests are always mandatory before any space mission is flown into space. The collected results of these tests are mainly temperatures of the different parts of the spacecraft (nodes) for different mission scenarios. The measured temperatures always show differences with the expected values coming from the computer thermal mathematical models. The origin of these differences is partially related to the inherent error coming from physical measurements. The thermal parameters that compose the computer thermal mathematical models must always be correlated with the results coming from tests. This paper studies, through three thermal models, the difficulties that are found in the correlation process when the measured temperatures reach a certain level of error. Thermal parameters become more difficult to be identified when the measurement error level increases. However, the temperature fields obtained with these poor thermal parameters are good enough for the mission thermal analysis. Several error levels, different load cases and correlation for steady-state and transient cases are studied to probe these findings.

A method is described for controlling the heat input in three-dimensional surfacing by means of a numerical algorithm determining the required parameter variation over time in mathematical modeling of the thermal problem. The goal is to ensure stable surfacing, the required geometric characteristics of the multilayer product, and the absence of defects. [ABSTRACT FROM AUTHOR]

This work proposes an active thermal management technology that operates ac drive inverters safely at thermal limits to maximize their current and torque capability. For that purpose, the technology exploits two fundamental opportunities: First, it monitors the coolant and junction temperature to adaptively determine the maximal peak current capability that increases at low coolant temperature. Second, it takes advantage of the thermal impedance frequency response function $Z_{\mathrm{th}}(\text {j}\omega)$ that decays with higher frequencies. Thus, larger currents are feasible at higher excitation frequencies without increasing peak junction temperature, because the associated transient losses are absorbed by the thermal capacitance of the power module. This article presents a unique active thermal management algorithm that addresses the two identified opportunities. It utilizes primarily a reduced-order electrothermal real-time model as well as negative temperature coefficient thermistor temperature information. Thus, it can be applied on most drive systems with small software modifications to adaptively maximize its current capability. To make this technology applicable in ac drives, this article also proposes torque control strategies that utilize variable current limits and discusses essential design limitation. With the introduced technology, state-of-the-art drive inverters can operate safely at up to 200% overload current and torque across a wide speed range. This supports the development of highly reliable drives with increased base speed range and power density that save space, cost, and resources. [ABSTRACT FROM AUTHOR]

Implementing multifunctional bioregenerative technologies may provide mission carbon loop closure while simultaneously addressing multiple environmental control and life support system requirements. This paper proposes using water-based algal medium for thermal control of the spacecraft cabin, while taking advantage of the algae's photosynthetic activity for air revitalization. Consequently, this could expose the algal culture to transient thermal environments fluctuating between +4 °C and +30 °C, in the span of minutes, reflecting the operation of the International Space Station (ISS) internal thermal control and cabin system. This paper presents an initial investigation of the metabolic response of Chlorella vulgaris to transient environmental temperatures, reflecting temperature ranges and cycling frequency of the ISS cooling loop (+9 °C to +27 °C, 30 min). The constant 19 °C control represented the time-averaged temperature of the cycled condition. Growth and acclimation were observed in both tested conditions through pH, dissolved oxygen, optical density, and photosynthetic quantum yield measurements. However, there was significant reduction in the oxygen production rate, measured pH, and optical density for the cycled temperature condition when compared to the control (cycled temperature = 0.95 gO 2 L−1 d−1, pH = 6.75, OD = 0.05; control = 1.17 gO 2 L−1 d−1, pH = 8.20, OD = 0.08). No significant reduction in growth rate or photosynthetic quantum yield were recorded between the two tested conditions. Growth rate of the cycled temperature condition reflected those of psychrotolerant algae, suggesting some amount of culture acclimation to the rapidly dynamic environment. Results suggest that while C. vulgaris was viable within the tested temperature environment reflecting the ISS thermal control loop and cabin, there was a measurable reduction in the oxygen production rate. • A photobioreactor for simultaneous spacecraft thermal control and air revitalization. • Chlorella survive extreme thermal profile of spacecraft thermal control. • Oxygen production rate significantly less for cycled temperature algae. • Minimal cellular stress documented for steady and cycled temperature algae. [ABSTRACT FROM AUTHOR]

The Space Robotics Laboratory (SRL) of Tohoku University has developed a 50-kg-class microsatellite called RISESAT, which was launched in January 2019. The main missions of this satellite are to conduct earth observation using a high-resolution telescope and perform a demonstration of optical communication. To achieve these missions, it is necessary to maintain the on-board components in a specified safe temperature range. In this satellite, on-board components such as the battery and power control unit are mounted to the central pillars of the satellite structure, which are insulated from the outer panels, and are thus not easily affected by the external environment. Therefore, it is important to determine the amount of heat generation by the components as well as the heat transfer parameters between structure panels. The purpose of this study is to determine the parameters such as thermal contact conductance between structure panels and heat generation of the components. We conducted the thermal vacuum tests to improve the accuracy of the determination of these parameters. Finally, we analyzed the flight data and evaluated the validity of the parameter determination using data from the regular operations phase of the mission. The seasonal effects on the thermal design were also evaluated using data from the first 480 days after launch. [ABSTRACT FROM AUTHOR]

The Space Robotics Laboratory (SRL) of Tohoku University and ALE Co., Ltd. developed a 60-kg-class microsatellite known as the ALE-1, which was launched in January 2019. The main mission was to generate artificial meteors. To achieve this, the temperature of the ALE-1 on-board components must be strictly maintained within specified ranges of safe operation. This is particularly critical because high power consumption is required for the mission. The purpose of this study is to propose a heat transfer parameter determination method using an experimental equation to calculate the thermal contact conductance. Additionally, to improve the accuracy of the heat transfer parameter determination, a thermal vacuum test was conducted and the experimental equation was calibrated. This study also discusses the significance and necessity of calibrating the experimental equation. Finally, the validity of the heat transfer parameters obtained by the ground test was evaluated by comparison with actual flight data. In the flight data analysis, the change in solar cell absorptivity owing to variations in the battery state-of-charge is also considered. The flight data analysis covers the early orbit entry phase and the period after high power consumption. [ABSTRACT FROM AUTHOR]

The present work deals with thermal regulation of a spherical electronic device used in naval navigation techniques. Cooling is achieved by means of porous media saturated with water–copper nanofluid contained in another sphere kept isothermal. Nanofluid volume fraction varies between 0 (pure water) and 5%, Rayleigh number ranges from 6.5 × 106 to 1.32 × 109, while ratio between the thermal conductivity of the porous material's matrix and that of water varies in the 0–40 range. Results for different configurations obtained through variation of these three influencing parameters show that the thermal conductivity ratio has a strong influence on the component's average surface temperature, while the fraction volume has a moderate influence throughout the range of the considered Rayleigh number. Evolution of the average temperature versus the Rayleigh number is conventional of the power type. It can be calculated through the correlation proposed in this work for any combination of the three influencing parameters. This work complements a recent study where heat transfer occurring around the active sphere is quantified. This optimizes the thermal sizing of the assembly and enhances its reliability. [ABSTRACT FROM AUTHOR]

In this study, a polymer-stabilised cholesteric liquid crystal film with broadband reflection was prepared by using a nanofibre film loaded with chiral dopants as the carrier. The nanofibre film prepared by the electrospinning technology ensures that chiral dopants can be uniformly distributed on the film and can be controlled release during the heating process. In order to obtain the maximum non-uniform distribution of the pitch, a series of investigations were conducted on the concentration of the polymerised monomer, polymerisation temperature, and intensity of the ultraviolet light. By screening different experimental conditions, the optimal conditions for broadening the reflection band were obtained, and the reflection bandwidth was broadened from 270 to 425 nm. The prepared cholesteric liquid crystal films with broadband reflection characteristics have potential application value in many fields, such as light-brightening films, smart windows, infrared shielding devices, laser protective coatings, etc. [ABSTRACT FROM AUTHOR]

To access the enhancement effect of the topology optimization and porous foam structure, numerical studies were conducted to investigate the heat conduction enhancement (by metal foam, graphite foam, topologically optimized fins, and combinations of metal foam and topologically optimized fins) of phase change material (PCM (n-octadecane)) based tubular thermal energy storage unit for spacecraft. The results showed that metal foam performed better than topologically optimized fins and a combination of metal foam and topology optimized fins, of which conductive material, unit mass, and volume fraction of PCM were the same. Graphite foam (140 W/(m·K)) had the best heat transfer enhancing effect, making PCM melt much faster than other enhancing methods investigated. A multi-criteria decision-making (MCDM) method integrated with the combined weight and TOPSIS method was introduced to evaluate the preferred alternatives’ performance based on the energy storage time, equivalent density, and energy storage. The evaluation pointed out that 3% topologically optimized aluminum fins with 98% copper foam had the best comprehensive performance. This study guided the optimal design of latent heat thermal energy storage units for spacecraft under microgravity.

Industrial power plant buildings differ from all other types of buildings, mainly due to their significant heights and volumes without internal floor sections, exceptionally heat gains during daily work, and potentially high fire risk. Those buildings consist of boiler and turbine houses with multilevel stairways. This complicated architecture creates an extraordinary natural thermal stack effect, causing special ventilation and smoke control systems requirements, adapted to their specific structures and internal conditions. The paper demonstrates a proposal for optimal thermal smoke control ventilation solutions in industrial power plant buildings designated on the basis of performance-based calculations and confirmed by CFD simulations. It demonstrates the possibilities of using daily ventilation in the boiler houses in a function of smoke control systems in the event of a fire and defines fundamental rules for designing the system. Additionally, a new method of sufficient staircase (pylons) protection with a modified pressurization system is proposed.

To achieve the automation of blast furnace operation, an automatic control system for hot metal temperature (HMT) was developed. Nonlinear model predictive control (NMPC) which predicts up to ten-hour-ahead HMT and calculates appropriate control actions of pulverized coal rate (PCR) was constructed. Simulation validation showed that the NMPC algorithm generates control actions similar to those by the operators and that HMT can be maintained within ±10 °C of the set point. The automatic control system using NMPC was then implemented in an actual plant. As a result, the developed control system suppressed the effects of disturbances, such as the changes in the coke ratio and blast volume, and successfully reduced the average control error of HMT by 4.6 °C compared to the conventional manual operation. The developed control system has contributed to the reduction of reducing agent rate (RAR) and CO2 emissions.

Ultra-thin microstructures of eutectic aluminum alloys have attracted attention due to their excellent mechanical properties. In this context, it is known that the massive production of industrial components may require adaptations in the processing routes with severe thermal control. Considering the benefits of molding applications, knowledge of proper conditions of the metal/mold interface is essential. The interfacial heat transfer efficiency controls the solidification kinetics and so the microstructure evolution. Furthermore, much of the existing work in this field involves the use of either water-cooled or massive copper molds. The goal is achieving moderate or fast cooling conditions and produce refined structures. In this sense, the association of the interfacial heat transfer coefficient, h, with desired microstructures can expand the application to other types of mold and process conditions. In this respect, the present research work applies a numerical mathematical model based on an inverse heat conduction problem (IHCP) for the solidification of relevant binary eutectic alloys, considered as priority for the production of ultrafine eutectics. It was demonstrated the compromise existing between the overall interfacial coefficient hg and the eutectic spacing for the Al-6.3 wt% Ni, Al-33 wt% Cu, Al-wt.12% Si and Al-1.0 wt% Co eutectic alloys. Expressions relating hg as a function of time (t) and hg versus the representative eutectic microstructural spacing (λ) of each alloy are proposed. The hg vs λ expressions allow inferring hg values necessary to induce the formation of ultrafine λ values.

Introduction: Cold water imposes many risks to the diver. These risks include decompression illness, physical and cognitive impairment, and hypothermia. Cognitive impairment can be estimated using a critical flicker fusion frequency (CFFF) test, but this method has only been used in a few studies conducted in an open water environment. We studied the effect of the cold and a helium-containing mixed breathing gas on the cognition of closed circuit rebreather (CCR) divers.Materials and Methods: Twenty-three divers performed an identical dive with controlled trimix gas with a CCR device in an ice-covered quarry. They assessed their thermal comfort at four time points during the dive. In addition, their skin temperature was measured at 5-min intervals throughout the dive. The divers performed the CFFF test before the dive, at target depth, and after the dive.Results: A statistically significant increase of 111.7% in CFFF values was recorded during the dive compared to the pre-dive values (p < 0.0001). The values returned to the baseline after surfacing. There was a significant drop in the divers’ skin temperature of 0.48°C every 10 min during the dive (p < 0.001). The divers’ subjectively assessed thermal comfort also decreased during the dive (p = 0.01).Conclusion: Our findings showed that neither extreme cold water nor helium-containing mixed breathing gas had any influence on the general CFFF profile described in the previous studies from warmer water and where divers used other breathing gases. We hypothesize that cold-water diving and helium-containing breathing gases do not in these diving conditions cause clinically relevant cerebral impairment. Therefore, we conclude that CCR diving in these conditions is safe from the perspective of alertness and cognitive performance.

Including a multifunctional, bioregenerative algal photobioreactor for simultaneous air revitalization and thermal control may aid in carbon loop closure for long-duration surface habitats. However, using water-based algal media as a cabin heat sink may expose the contained culture to a dynamic, low temperature environment. Including psychrotolerant microalgae, native to these temperature regimes, in the photobioreactor may contribute to system stability. This paper assesses the impact of a cycled temperature environment, reflective of spacecraft thermal loops, to the oxygen provision capability of temperate Chlorella vulgaris and eurythermic Antarctic Chlorophyta. The tested 28-min temperature cycles reflected the internal thermal control loops of the International Space Station (C. vulgaris, 9–27°C; Chlorophyta-Ant, 4–14°C) and included a constant temperature control (10°C). Both sample types of the cycled temperature condition concluded with increased oxygen production rates (C. vulgaris; initial: 0.013 mgO2 L–1, final: 3.15 mgO2 L–1 and Chlorophyta-Ant; initial: 0.653 mgO2 L–1, final: 1.03 mgO2 L–1) and culture growth, suggesting environmental acclimation. Antarctic sample conditions exhibited increases or sustainment of oxygen production rates normalized by biomass dry weight, while both C. vulgaris sample conditions decreased oxygen production per biomass. However, even with the temperature-induced reduction, cycled temperature C. vulgaris had a significantly higher normalized oxygen production rate than Antarctic Chlorophyta. Chlorophyll fluorometry measurements showed that the cycled temperature conditions did not overly stress both sample types (FV/FM: 0.6–0.75), but the Antarctic Chlorophyta sample had significantly higher fluorometry readings than its C. vulgaris counterpart (F = 6.26, P < 0.05). The steady state C. vulgaris condition had significantly lower fluorometry readings than all other conditions (FV/FM: 0.34), suggesting a stressed culture. This study compares the results to similar experiments conducted in steady state or diurnally cycled temperature conditions. Recommendations for surface system implementation are based off the presented results. The preliminary findings imply that both C. vulgaris and Antarctic Chlorophyta can withstand the dynamic temperature environment reflective of a thermal control loop and these data can be used for future design models.

Including a multifunctional, bioregenerative algal photobioreactor for simultaneous air revitalization and thermal control may aid in carbon loop closure for long-duration surface habitats. However, using water-based algal media as a cabin heat sink may expose the contained culture to a dynamic, low temperature environment. Including psychrotolerant microalgae, native to these temperature regimes, in the photobioreactor may contribute to system stability. This paper assesses the impact of a cycled temperature environment, reflective of spacecraft thermal loops, to the oxygen provision capability of temperate Chlorella vulgaris and eurythermic Antarctic Chlorophyta. The tested 28-min temperature cycles reflected the internal thermal control loops of the International Space Station (C. vulgaris , 9–27°C; Chlorophyta-Ant, 4–14°C) and included a constant temperature control (10°C). Both sample types of the cycled temperature condition concluded with increased oxygen production rates (C. vulgaris ; initial: 0.013 mgO2 L–1, final: 3.15 mgO2 L–1 and Chlorophyta-Ant; initial: 0.653 mgO2 L–1, final: 1.03 mgO2 L–1) and culture growth, suggesting environmental acclimation. Antarctic sample conditions exhibited increases or sustainment of oxygen production rates normalized by biomass dry weight, while both C. vulgaris sample conditions decreased oxygen production per biomass. However, even with the temperature-induced reduction, cycled temperature C. vulgaris had a significantly higher normalized oxygen production rate than Antarctic Chlorophyta. Chlorophyll fluorometry measurements showed that the cycled temperature conditions did not overly stress both sample types (FV/FM: 0.6–0.75), but the Antarctic Chlorophyta sample had significantly higher fluorometry readings than its C. vulgaris counterpart (F = 6.26, P < 0.05). The steady state C. vulgaris condition had significantly lower fluorometry readings than all other conditions (FV/FM: 0.34), suggesting a stressed culture. This study compares the results to similar experiments conducted in steady state or diurnally cycled temperature conditions. Recommendations for surface system implementation are based off the presented results. The preliminary findings imply that both C. vulgaris and Antarctic Chlorophyta can withstand the dynamic temperature environment reflective of a thermal control loop and these data can be used for future design models. [ABSTRACT FROM AUTHOR]

Introduction: Cold water imposes many risks to the diver. These risks include decompression illness, physical and cognitive impairment, and hypothermia. Cognitive impairment can be estimated using a critical flicker fusion frequency (CFFF) test, but this method has only been used in a few studies conducted in an open water environment. We studied the effect of the cold and a helium-containing mixed breathing gas on the cognition of closed circuit rebreather (CCR) divers. Materials and Methods: Twenty-three divers performed an identical dive with controlled trimix gas with a CCR device in an ice-covered quarry. They assessed their thermal comfort at four time points during the dive. In addition, their skin temperature was measured at 5-min intervals throughout the dive. The divers performed the CFFF test before the dive, at target depth, and after the dive. Results: A statistically significant increase of 111.7% in CFFF values was recorded during the dive compared to the pre-dive values (p < 0.0001). The values returned to the baseline after surfacing. There was a significant drop in the divers' skin temperature of 0.48°C every 10 min during the dive (p < 0.001). The divers' subjectively assessed thermal comfort also decreased during the dive (p = 0.01). Conclusion: Our findings showed that neither extreme cold water nor helium-containing mixed breathing gas had any influence on the general CFFF profile described in the previous studies from warmer water and where divers used other breathing gases. We hypothesize that cold-water diving and helium-containing breathing gases do not in these diving conditions cause clinically relevant cerebral impairment. Therefore, we conclude that CCR diving in these conditions is safe from the perspective of alertness and cognitive performance. [ABSTRACT FROM AUTHOR]

Electric cars, in addition to representing an ecological solution, represent a turning point in terms of renewal for the world economy. One of the main problems of electric cars is given by the thermal control of their batteries, as below and above a certain temperature range, they abruptly decrease the range of the vehicle, creating inconvenience to the owners of such cars. The thermal control of lithium batteries for electric cars must therefore take into account both the problems of thermal increase due to the operation of the battery itself, and the climatic conditions outside the vehicle that impact, if above a certain range, negatively on the performance of the car, decreasing both the range and the life of the battery. In this study, an attempt is made to control the temperature peaks due to the operation of the battery itself to this end, a thermal control system with metal foam phase change material is studied in order to evaluate the heat transfer behavior for use in the cooling of lithium batteries. A two-dimensional model is considered to numerically study the thermal control with different charge and discharge cycles. The battery is simulated as a wall-mounted heat flow. Thermal control is achieved by means of an inner layer of copper foam and phase change material, PCM (paraffin) and the outer surfaces are cooled by convective flow. The governing equations, written assuming local thermal equilibrium for the metal foam, are solved by the finite volume method using the commercial Ansys-Fluent code. Several cases are simulated for different values of external convective heat transfer coefficient. Results, performed for metal foams with different PPIs and porosities, are provided in terms of temperature fields and liquid fraction, heat transfer behaviors such as surface temperature profiles as a function of time, and temperature distributions along the outer surface of the battery for the different cases. In addition, some comparisons with pure PCM within the thermal control system are provided to show the advantages of the composite thermal control system with PCM within the metal foam. The results obtained show that the best solution among those studied is given by the use of copper foams filled with paraffin PCM. [ABSTRACT FROM AUTHOR]

In this article, an approach for boosting the efficiency of energy management strategies (EMSs) in fuel cell hybrid electric vehicles using an online systemic management of the fuel cell system (FCS) is put forward. Unlike other similar works which solely determine the requested current from the FCS, this article capitalizes on simultaneous regulation of current and temperature, which have different dynamic behavior. In this regard, first, an online systemic management scheme is developed to guarantee the supply of the requested power from the stack with the highest efficiency. This scheme is based on an updatable three-dimensional map which relates the requested power from the stack to its optimal temperature and current. Second, two different EMSs are used to distribute the power between the FCS and battery. The EMSs’ constraints are constantly updated by the online model to embrace the stack performance drifts owing to degradation and operating conditions variation. Finally, the effect of integrating the developed online systemic management into the EMSs’ design is experimentally scrutinized under two standard driving cycles and indicated that up to 3.7% efficiency enhancement can be reached by employing such a systemic approach. Moreover, FCS's health adaptation unawareness can increase the hydrogen consumption up to 6.6%. [ABSTRACT FROM AUTHOR]

[Display omitted] • Electrical vehicle safety using optical shuttering action. • A liquid crystal ingredient optical shutter is devised and characterized. • Optically shuttering action characteristics are discussed. • Compilation traditional devices indicates superior features of liquid crystal device. This intermediate phase between solid and liquid enables liquid crystal engineers for various interesting yet fascinating thermo-optical applications. One such application of exploited for electric vehicle safety is optical shutter realized using thermotropic liquid crystals. Optical shutters are essential components in various optical systems, in providing control over the transmission of visible light. These shutters are categorized into various types of mechanical shutters, electro-optical shutters, liquid crystal optical shutters (LCOS) etc. liquid crystal cells and polarizing elements to quickly change the transmittance of light, making them ultimate for applications such as imaging and precision illumination. In this work, we explored the experimental techniques, key specifications, features, and applications of an optical shutter developed using liquid crystalline material LCOS. [ABSTRACT FROM AUTHOR]

• A vision-based model for estimating real-time personal factors was developed. • The model simultaneously estimates metabolic rate and clothing insulation. • A real-time PMV-based control algorithm was developed for both individual and group. • The algorithm enhanced thermal comfort of occupants compared to conventional methods. • The core technique was verified to balance energy and comfort in building operations. To optimize thermal comfort for occupants' wellbeing and health care, it's essential to adjust heating and cooling systems in real-time based on occupants' thermal preferences. For this, personal factors affect individual thermal comfort, such as metabolic rate and clothing insulation, should be estimated in real-time. The aim of this research is introducing an intelligent model capable of estimating metabolic rate and clothing insulation values from indoor images, suitable for both single and multi-occupant scenarios. Additionally, a control algorithm considering a real-time predicted mean vote (PMV), was developed using the proposed model, and its implications for thermal comfort and energy efficiency were investigated. Utilizing advanced computer vision methodologies, the model achieved a remarkable 95% training accuracy, and its reliability was further validated through experimentation. Evaluations of the PMV-based algorithm underscored its efficacy in enhancing thermal comfort relative to conventional methods in both individual and multi-occupant settings. Conversely, energy use was contingent upon the personal factors. In group settings, the mode values of metabolic rate and clothing insulation were effective for determining a representative PMV. In conclusion, the real-time PMV-based control represents a pioneering approach to augment thermal comfort using actual occupant data, paving the way for a synergistic balance between comfort augmentation and energy saving. [ABSTRACT FROM AUTHOR]

In this paper, we present an optical structure for two-stage beam combination to realize a high-power fiber-coupled diode laser source. In the first stage, dense spectral combination based on reflecting volume Bragg gratings is implemented for combining five diode laser blocks with a spectral separation of 1.5 nm, to a high output power submodule. In the second stage, submodules are further coaxially multiplexed by polarization beam combination and coarse spectral combination to obtain a higher output power. In the process of the beam combination, thermal effects of combining elements are also investigated. By using a temperature control, the diode laser source can steadily produce 3120-W power from an optical fiber with 105-μm core diameter and 0.2 numerical aperture. This paper demonstrates the benefits of this combination structure and the effectiveness of the temperature control.

The road transport industry faces the need to develop its fleet for lower energy consumption, pollutants and CO2 emissions. Waste heat recovery systems with Thermoelectric Generators (TEGs) can directly convert the exhaust heat into electric energy, aiding the electrical needs of the vehicle, thus reducing its dependency on fuel energy. The present work assesses the optimisation and evaluation of a temperature-controlled thermoelectric generator (TCTG) concept to be used in a commercial heavy-duty vehicle (HDV). The system consists of a heat exchanger with wavy fins (WFs) embedded in an aluminium matrix along with vapour chambers (VCs), machined directly into the matrix, that grant the thermal control based on the spreading of local excess heat by phase change, as proposed by the authors in previous publications and patents. The TCTG concept behaviour was analysed under realistic driving conditions. An HDV with a 16 L Diesel engine was simulated in AVL Cruise to obtain the exhaust gas temperature and mass flow rate for each point of two cycle runs. A model proposed in previous publications was adapted to the new fin geometry and vapour chamber configuration and used the AVL Cruise data as input. It was possible to predict the thermal and thermoelectric performance of the TCTG along the corresponding driving cycles. The developed system proved to have a good capacity for applications with highly variable thermal loads since it was able to uncouple the maximisation of heat absorption from the regulation of the thermal level at the hot face of the TEG modules, avoiding both thermal dilution and overheating. This was achieved by the controlled phase change temperature of the heat spreader, that would ensure the spreading of the excess heat from overheated to underheated areas of the generator instead of wasting excess heat. A maximum average electrical production of 2.4 kW was predicted, which resulted in fuel savings of about 2% and CO2 emissions reduction of around 37 g/km.

Effects of current density, oxidation time and sealing on thermal control properties of anodic coatings of magnesium-lithium alloy were investigated. The microstructure, thermal control properties, adhesion properties, thickness, thermal cycling test and corrosion resistance were studied. The results indicate that high infrared emittance (εH) increases with the increase of current density and oxidation time, eventually stabilizes at around 0.85. Sealing has little effect on high infrared emittance (εH); variation of εH is in the range of less than 0.05. After 96 h neutral salt spray test, the coating shows good corrosion resistance.