scholarly journals Evaluating the efficiency of utilizing selectively optimized metamaterial nanostructures for passive radiative cooling of satellites and components

2019 ◽  
Vol 6 ◽  
pp. 110-123
Author(s):  
Federico Moreno ◽  
Swapnil Poudyal ◽  
Otto Cranwell ◽  
Ben Andrew
Keyword(s):  
Meta Analysis ◽  
Inductive Reasoning ◽  
Visible Spectrum ◽  
Optical Filters ◽  
Thermal Control ◽  
Cooling Power ◽  
Radiative Cooling ◽  
Temperature Sensitive ◽  
Selective Absorption ◽  
Nanophotonic Structures

The need for efficient, smart radiators and thermal control technologies will be imperative to ensure the longevity of satellites and for carrying out temperature sensitive operations in space. Advancement in nanofabrication techniques has brought about the ability to create metamaterial nanostructures and selectively control their optical properties so that they reflect better in the visible spectrum and strongly emit in the infrared spectrum, which allows for better cooling. This meta-analysis looks at contemporary research that has utilised metamaterial nanostructures for passive radiative cooling attempting to identify the cooling trends among these structures. The absorbance, emissivity and reflection spectra of these structures are compared, and their effectiveness compared to conventional coolant coatings is critiqued upon. The defining thermodynamic parameters for this study were radiative cooling power and temperature reduction. Through inductive reasoning, we predict that the emissivity in the infrared of a pyramidal layered structure of Al2O3, TiO2 and SiO2 can outperform current material choices. Improving efficiency with the prediction outlined can provide increased radiative cooling. Keywords: Passive radiative cooling; thermal radiation; metamaterials; broadband optical filters; selective absorption and emission; two-dimensional thin film coatings; nanophotonic structures

scholarly journals Radiative sky cooling: fundamental physics, materials, structures, and applications

Nanophotonics ◽  
2017 ◽  
Vol 6 (5) ◽  
pp. 997-1015 ◽  
Author(s):  
Xingshu Sun ◽  
Yubo Sun ◽  
Zhiguang Zhou ◽  
Muhammad Ashraful Alam ◽  
Peter Bermel
Keyword(s):  
Infrared Detectors ◽  
Detailed Comparison ◽  
Radiative Cooling ◽  
Temperature Sensitive ◽  
Bulk Materials ◽  
Fundamental Physics ◽  
Potential Applications ◽  
Modeling And Experiments ◽  
Ancient Times ◽  
Nanophotonic Structures

AbstractRadiative sky cooling reduces the temperature of a system by promoting heat exchange with the sky; its key advantage is that no input energy is required. We will review the origins of radiative sky cooling from ancient times to the modern day, and illustrate how the fundamental physics of radiative cooling calls for a combination of properties that may not occur in bulk materials. A detailed comparison with recent modeling and experiments on nanophotonic structures will then illustrate the advantages of this recently emerging approach. Potential applications of these radiative cooling materials to a variety of temperature-sensitive optoelectronic devices, such as photovoltaics, thermophotovoltaics, rectennas, and infrared detectors, will then be discussed. This review will conclude by forecasting the prospects for the field as a whole in both terrestrial and space-based systems.

scholarly journals DIGITAL IMAGE ANALYSIS OF THE VISIBLE REGION THROUGH SIMULATION OF ROCK ART PAINTINGS

2016 ◽  
Author(s):  
Berta Carrión-Ruiz ◽  
Silvia Blanco-Pons ◽  
Jose Luis Lerma
Keyword(s):  
Rock Art ◽  
Visible Region ◽  
Visible Spectrum ◽  
Principal Component ◽  
Optical Filters ◽  
Visible Range ◽  
Redundant Data ◽  
The Difference ◽  
Entire Visible Spectrum ◽  
New Research

Non-destructive rock art recording techniques are getting special attention in the last years, opening new research lines in order to improve the level of documentation and understanding of our rich legacy. This paper applies the principal component analysis (PCA) technique in images that include wavelengths between 400-700 nm (visible  range). Our approach is focused on determining the difference provided by the image processing of the visible region through four spectral images versus an image that encompasses the entire visible spectrum. The images were taken by means of optical filters that take specific wavelengths and exclude parts of the spectrum. Simulation of rock art is prepared in laboratory. For this purpose, three different pigments were made simulating the material composition of rock art paintings. The advantages of studying the visible spectrum in separate images are analysed. In addition, PCA is applied to each of the images to reduce redundant data. Finally, PCA is applied to the image that contains the entire visible spectrum and is compared with previous results. Through the results of the four visible spectral images one can begin to draw conclusions about constituent painting materials without using decorrelation techniques.

scholarly journals The Application of Passive Radiative Cooling in Greenhouses

2019 ◽  
Vol 11 (23) ◽  
pp. 6703 ◽  
Author(s):  
Chia-Hsin Liu ◽  
Chyung Ay ◽  
Chun-Yu Tsai ◽  
Maw-Tien Lee
Keyword(s):  
Convection Heat Transfer ◽  
Cooling Power ◽  
Radiative Cooling ◽  
Natural Convection Heat Transfer ◽  
Convection Heat ◽  
Monolayer Film ◽  
Cooling Method ◽  
The World ◽  
Oxide Particles ◽  
Reducing Energy

At present, greenhouses are used to grow a variety of crops around the world. However, with the change of climate, the increasingly harsh weather makes it more and more disadvantageous for people to work inside, and plants are difficult to grow. Previous research has illustrated that radiative cooling can be realized by using certain nonmetal oxide particles created for emission in an infrared atmospheric transparency window, which is an environmentally friendly cooling method due to reducing energy consumption. Polyethylene (PE)-based formulations with a UV stabilizer and nonmetal oxide particles (NOP) were first granulated and then formed a monolayer film by co-injection molding. The experimental results show that due to passive radiative cooling, under the environmental conditions of 35 °C, and only considering the natural convection heat transfer, the net cooling power of the greenhouse film developed in this study is 28 W·m−2 higher than that of the conventional PE film. The temperature inside the simulated greenhouse cladded with the new greenhouse covering was on average 2.2 °C less than that of the greenhouse with the conventional PE film.

The Neural Correlates of Relational Reasoning: A Meta-analysis of 47 Functional Magnetic Resonance Studies

2018 ◽  
Vol 30 (11) ◽  
pp. 1734-1748 ◽  
Author(s):  
Julia Wertheim ◽  
Marco Ragni
Keyword(s):  
Spatial Information ◽  
Meta Analysis ◽  
Inductive Reasoning ◽  
Neural Correlates ◽  
Relational Reasoning ◽  
Cognitive Mechanisms ◽  
Train Station ◽  
Frontoparietal Network ◽  
Open Questions ◽  
The Impact

It is a core cognitive ability of humans to represent and reason about relational information, such as “the train station is north of the hotel” or “Charles is richer than Jim.” However, the neural processes underlying the ability to draw conclusions about relations are still not sufficiently understood. Central open questions are as follows: (1) What are the neural correlates of relational reasoning? (2) Where can deductive and inductive reasoning be localized? (3) What is the impact of different informational types on cerebral activity? For that, we conducted a meta-analysis of 47 neuroimaging studies. We found activation of the frontoparietal network during both deductive and inductive reasoning, with additional activation in an extended network during inductive reasoning in the basal ganglia and the inferior parietal cortex. Analyses revealed a double dissociation concerning the lateral and medial Brodmann's area 6 during deductive and inductive reasoning, indicating differences in terms of processing verbal information in deductive and spatial information in inductive tasks. During semantic and symbolic tasks, the frontoparietal network was found active, whereas geometric tasks only elicited prefrontal activation, which can be explained by the reduced demand for the construction of a mental representation in geometric tasks. Our study provides new insights into the cognitive mechanisms underlying relational reasoning and clarifies previous controversies concerning involved brain areas.

Restoration of thermoregulation after exercise

2017 ◽  
Vol 122 (4) ◽  
pp. 933-944 ◽  
Author(s):  
Glen P. Kenny ◽  
Ryan McGinn
Keyword(s):  
Heat Loss ◽  
Core Temperature ◽  
Current Knowledge ◽  
Thermal Control ◽  
The Body ◽  
Body Core Temperature ◽  
Whole Body ◽  
Temperature Sensitive ◽  
Internal Core ◽  
Body Core

Performing exercise, especially in hot conditions, can heat the body, causing significant increases in internal body temperature. To offset this increase, powerful and highly developed autonomic thermoregulatory responses (i.e., skin blood flow and sweating) are activated to enhance whole body heat loss; a response mediated by temperature-sensitive receptors in both the skin and the internal core regions of the body. Independent of thermal control of heat loss, nonthermal factors can have profound consequences on the body’s ability to dissipate heat during exercise. These include the activation of the body’s sensory receptors (i.e., baroreceptors, metaboreceptors, mechanoreceptors, etc.) as well as phenotypic factors such as age, sex, acclimation, fitness, and chronic diseases (e.g., diabetes). The influence of these factors extends into recovery such that marked impairments in thermoregulatory function occur, leading to prolonged and sustained elevations in body core temperature. Irrespective of the level of hyperthermia, there is a time-dependent suppression of the body’s physiological ability to dissipate heat. This delay in the restoration of postexercise thermoregulation has been associated with disturbances in cardiovascular function which manifest most commonly as postexercise hypotension. This review examines the current knowledge regarding the restoration of thermoregulation postexercise. In addition, the factors that are thought to accelerate or delay the return of body core temperature to resting levels are highlighted with a particular emphasis on strategies to manage heat stress in athletic and/or occupational settings.

scholarly journals Quo vadis Common Agricultural Policy of the European Union?

Management ◽  
2019 ◽  
Vol 23 (2) ◽  
pp. 295-309 ◽  
Author(s):  
Sebastian Stępień ◽  
Andrzej Czyżewski
Keyword(s):  
European Union ◽  
Agricultural Policy ◽  
Common Agricultural Policy ◽  
Agricultural Sector ◽  
Meta Analysis ◽  
Inductive Reasoning ◽  
The European Union ◽  
Macroeconomic Conditions ◽  
Quo Vadis ◽  
The Eu

Summary The agricultural policy of the European Union - Common Agricultural Policy (CAP) - was introduced in the 1960s as the first EU policy. Over the next decades it constituted the largest share in the expenditure of the EU budget. Today, although cohesion policy has replaced it in the first place, it is still being prioritized by the countries of the Community. Observation of the next financial perspectives, however, allows to conclude that the nature of the CAP is changing, which is a manifestation of the evolution of views on the role of the food sector in the economic development of the European Union. The aim of the study is to indicate the directions of reforms of the Common Agricultural Policy during its sixty-year functioning, the reasons for these changes and the consequences they have had for the agricultural sector in EU countries. These outcomes were supplemented by outlining the perspectives for the development of the EU agricultural policy in the coming years. The authors focused on the basic instruments of the CAP including income-generating, environmental and rural development-related. On the basis of the analysis of objectives and instruments of the CAP, it was stated that it departed from traditional market support to create more sophisticated intervention related to the changing macroeconomic conditions and expectations of the society. The paper is a review, with elements of meta-analysis, deduction and inductive reasoning.

scholarly journals UAS-Based Archaeological Remote Sensing: Review, Meta-Analysis and State-of-the-Art

Drones ◽  
2020 ◽  
Vol 4 (3) ◽  
pp. 46 ◽  
Author(s):  
Efstathios Adamopoulos ◽  
Fulvio Rinaudo
Keyword(s):  
Remote Sensing ◽  
State Of The Art ◽  
Meta Analysis ◽  
Visible Spectrum ◽  
Unmanned Aircraft ◽  
Future Research ◽  
Radar Sensors ◽  
Technological Developments ◽  
Aerial Platforms ◽  
Historical Sites

Over the last decade, we have witnessed momentous technological developments in unmanned aircraft systems (UAS) and in lightweight sensors operating at various wavelengths, at and beyond the visible spectrum, which can be integrated with unmanned aerial platforms. These innovations have made feasible close-range and high-resolution remote sensing for numerous archaeological applications, including documentation, prospection, and monitoring bridging the gap between satellite, high-altitude airborne, and terrestrial sensing of historical sites and landscapes. In this article, we track the progress made so far, by systematically reviewing the literature relevant to the combined use of UAS platforms with visible, infrared, multi-spectral, hyper-spectral, laser, and radar sensors to reveal archaeological features otherwise invisible to archaeologists with applied non-destructive techniques. We review, specific applications and their global distribution, as well as commonly used platforms, sensors, and data-processing workflows. Furthermore, we identify the contemporary state-of-the-art and discuss the challenges that have already been overcome, and those that have not, to propose suggestions for future research.

scholarly journals Quick Response Circulating Water Cooling of ±3 mK Using Dynamic Thermal Filtering

2020 ◽  
Vol 10 (16) ◽  
pp. 5483
Author(s):  
Yesheng Lu ◽  
Junning Cui ◽  
Jiubin Tan ◽  
Xingyuan Bian
Keyword(s):  
Temperature Control ◽  
Dynamic Performance ◽  
Cooling Water ◽  
Thermal Inertia ◽  
Temperature Stability ◽  
Thermal Control ◽  
Cooling Power ◽  
Quick Response ◽  
High Temperature Stability ◽  
Bidirectional Regulation

An enhanced circulating cooling water (CCW) machine is developed to simultaneously achieve high temperature stability and dynamic performance of CCW temperature control. Dynamic thermal filtering based on an auto-updatable thermal capacity medium is proposed to reduce the temperature fluctuation of the CCW. Agile thermal control is presented to realize a quick response and high resolution of temperature control, through thermal inertia minimization and bidirectional regulation of heating/cooling power. Experimental results indicate that a temperature stability of ±3 mK (peak to peak value) and a settling time of 128 s, corresponding to a 1 K step set value, are achieved. It can therefore be concluded that the developed machine can satisfy the challenging requirements of precision manufacturing.

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