scholarly journals Deployment of Solar Sails by Joule Effect: Thermal Analysis and Experimental Results

Aerospace ◽  
2020 ◽  
Vol 7 (12) ◽  
pp. 180
Author(s):  
Gianluigi Bovesecchi ◽  
Sandra Corasaniti ◽  
Girolamo Costanza ◽  
Fabrizio Paolo Piferi ◽  
Maria Elisa Tata
Keyword(s):  
Thermal Analysis ◽  
Solar Sail ◽  
Electrical Circuit ◽  
Nickel Titanium ◽  
Design Parameters ◽  
Space Vehicles ◽  
The Sun ◽  
Solar Sails ◽  
Joule Effect ◽  
Electrical Circuits

Space vehicles may be propelled by solar sails exploiting the radiation pressure coming from the sun and applied on their surfaces. This work deals with the adoption of Nickel-Titanium Shape Memory Alloy (SMA) elements in the sail deployment mechanism activated by the Joule Effect, i.e., using the same SMA elements as a resistance within suitable designed electrical circuits. Mathematical models were analyzed for the thermal analysis by implementing algorithms for the evaluation of the temperature trend depending on the design parameters. Several solar sail prototypes were built up and tested with different number, size, and arrangement of the SMA elements, as well as the type of the selected electrical circuit. The main parameters were discussed in the tested configurations and advantages discussed as well.

scholarly journals Deployment of Solar Sails by Joule Effect: Thermal Analysis and Experimental Results

2020 ◽  
Author(s):  
Gianluigi Bovesecchi ◽  
Sandra Corasaniti ◽  
Girolamo Costanza ◽  
Fabrizio Paolo Piferi ◽  
Maria Elisa Tata
Keyword(s):  
Thermal Analysis ◽  
Shape Memory Alloy ◽  
Solar Sail ◽  
Electrical Circuit ◽  
Design Parameters ◽  
Space Vehicles ◽  
The Sun ◽  
Solar Sails ◽  
Joule Effect ◽  
Electrical Circuits

Space vehicles may be propelled by solar sails exploiting the radiation pressure coming from the sun and applied on their surfaces. This work deals with the adoption of Shape-Memory Alloy (SMA) elements in the sail deployment mechanism activated by the Joule Effect, i.e. using the same SMA elements as a resistance within suitable designed electrical circuits. Mathematical models were analyzed for the thermal analysis by implementing algorithms for the evaluation of the temperature trend depending on the design parameters. Several solar sail prototypes were built up and tested with different number, size and arrangement of the SMA elements, as well as the type of the selected electrical circuit. The main parameters have been discussed in the tested configurations and advantages discussed as well.

scholarly journals A Novel Self-Deployable Solar Sail System Activated by Shape Memory Alloys

Aerospace ◽  
2019 ◽  
Vol 6 (7) ◽  
pp. 78 ◽  
Author(s):  
Gianluigi Bovesecchi ◽  
Sandra Corasaniti ◽  
Girolamo Costanza ◽  
Maria Elisa Tata
Keyword(s):  
Shape Memory Alloys ◽  
Shape Memory ◽  
Environmental Conditions ◽  
Solar Sail ◽  
Operating Conditions ◽  
Small Scale ◽  
Space Vehicles ◽  
Solar Sails ◽  
Suitable Material ◽  
Transfer Mechanisms

This work deals with the feasibility and reliability about the use of shape memory alloys (SMAs) as mechanical actuators for solar sail self-deployment instead of heavy and bulky mechanical booms. Solar sails exploit radiation pressure a as propulsion system for the exploration of the solar system. Sunlight is used to propel space vehicles by reflecting solar photons from a large and light-weight material, so that no propellant is required for primary propulsion. In this work, different small-scale solar sail prototypes (SSP) were studied, manufactured, and tested for bending and in three different environmental conditions to simulate as much as possible the real operating conditions where the solar sails work. Kapton is the most suitable material for sail production and, in the space missions till now, activated booms as deployment systems have always been used. In the present work for the activation of the SMA elements some visible lamps have been employed to simulate the solar radiation and time-temperature diagrams have been acquired for different sail geometries and environmental conditions. Heat transfer mechanisms have been discussed and the minimum distance from the sun allowing the full self-deployment of the sail have also been calculated.

Mathematical views of the fractional Chua's electrical circuit described by the Caputo-Liouville derivative

2021 ◽  
Vol 67 (1 Jan-Feb) ◽  
pp. 91
Author(s):  
N. Sene
Keyword(s):  
Caputo Derivative ◽  
Local Stability ◽  
Numerical Scheme ◽  
Equilibrium Points ◽  
Electrical Circuit ◽  
Maximal Lyapunov Exponent ◽  
Electrical Circuits ◽  
Adaptive Controls ◽  
Liouville Derivative

This paper revisits Chua's electrical circuit in the context of the Caputo derivative. We introduce the Caputo derivative into the modeling of the electrical circuit. The solutions of the new model are proposed using numerical discretizations. The discretizations use the numerical scheme of the Riemann-Liouville integral. We have determined the equilibrium points and study their local stability. The existence of the chaotic behaviors with the used fractional-order has been characterized by the determination of the maximal Lyapunov exponent value. The variations of the parameters of the model into the Chua's electrical circuit have been quantified using the bifurcation concept. We also propose adaptive controls under which the master and the slave fractional Chua's electrical circuits go in the same way. The graphical representations have supported all the main results of the paper.

scholarly journals Signal Processing and Analysis of Electrical Circuit

Electronics ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 17
Author(s):  
Adam Glowacz ◽  
Jose Alfonso Antonino Daviu
Keyword(s):  
Signal Processing ◽  
Electrical Circuit ◽  
Electrical Circuits ◽  
Electrical Systems

The analysis of electrical circuits is an essential task in the evaluation of electrical systems [...]

scholarly journals Effect of Core Mass and Alloy on Cyclic Fatigue Resistance of Different Nickel-Titanium Endodontic Instruments in Matching Artificial Canals

Materials ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 5734
Author(s):  
Sebastian Bürklein ◽  
Lennart Zupanc ◽  
David Donnermeyer ◽  
Karsten Tegtmeyer ◽  
Edgar Schäfer
Keyword(s):  
Fatigue Resistance ◽  
Cyclic Fatigue ◽  
Nickel Titanium ◽  
The Other ◽  
Design Parameters ◽  
Core Mass ◽  
Cross Sectional ◽  
Significance Level ◽  
Cross Sectional Design ◽  
The Impact

Instrument failure during root canal preparation is still a concern among endodontists. However, it remains unclear whether the use of more martensitic alloys or the cross-sectional design parameters (i.e., core mass) significantly improve fracture resistance. The aim of the study was to evaluate the impact of core mass and alloy on dynamic cyclic fatigue resistance of nickel-titanium endodontic instruments in matching artificial canals at body temperature. Two groups were tested. (A) taper 0.04: F360 (Komet, Lemgo, Germany), Twisted file (Sybron Endo, Glendora, CA, USA) (=TF), JIZAI (Mani, Tochigi, Japan) (=J_04) (all size #25) and the variable tapered TruNatomy (Dentsply, Ballaigues, Switzerland) (size #26) (=TN). (B) size #25; taper 0.06: (Mtwo (VDW, Munich, Germany), JIZAI (Mani) (=J_06), and variable tapered Hyflex EDM OneFile (Coltene Whaledent, Altstätten, Switzerland) (=HF). Time, number of cycles to fracture (NCF), and number and length of fractured fragments were recorded and statistically analysed using ANOVA Student-Newman-Keuls, Kruskal–Wallis or Chi-square test (significance level = 0.05). (A) TN showed the significantly shortest time until fracture, followed by TF, F360 and J_04 which also differed significantly, while NCF showed the following order: F360 < TN < TF < J_04 (p < 0.05). Only one J_04 but all instruments of the other groups fractured within the test-limit of 10 min. (B) Mtwo was significantly inferior concerning time until fracture and NCF, compared to J_06 and HF (p < 0.05), which did not differ significantly (p > 0.05). While all Mtwo instruments fractured, only four instruments failed in the other groups (p < 0.05). Within the limitations of this study, alloy and cross-sectional design (i.e., core mass) were critical factors regarding instrument failure, but none of these factors could be determined as a main parameter for increased or decreased time, and cycles to fracture. Rather, it seemed to be the interaction of multiple factors (e.g., longitudinal and cross-sectional design, alloy, and rotational speed) that was responsible for differences in the time and cycles to fracture. Nonetheless, all instruments had lifetimes that allow safe clinical use. However, the superiority or inferiority of an instrument with regard to cyclic fatigue based on laboratory results—even when identical trajectories are guaranteed—may be considered questionable, as the characteristics and design parameters of the instruments vary considerably, and the experimental setups lack additional clinical parameters and thus clinical relevance.

Combining Computational Fluid Dynamics (CFD) and Flow Network Modeling (FNM) for Design of a Multi-Chip Module (MCM) Cold Plate

2013 ◽  
Author(s):  
John Fernandes ◽  
Saeed Ghalambor ◽  
Akhil Docca ◽  
Chris Aldham ◽  
Dereje Agonafer ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Thermal Analysis ◽  
Computational Fluid Dynamics ◽  
Network Modeling ◽  
Computational Time ◽  
Design Parameters ◽  
Cold Plate ◽  
Original Solution ◽  
Flow Network ◽  
Computational Fluid Dynamics Cfd

The objective of the study is to improve on performance of the current liquid cooling solution for a Multi-Chip Module (MCM) through design of a chip-scale cold plate with quick and accurate thermal analysis. This can be achieved through application of Flow Network Modeling (FNM) and Computational Fluid Dynamics (CFD) in an interactive manner. Thermal analysis of the baseline cold plate design is performed using CFD to determine initial improvement in performance as compared to the original solution, in terms of thermal resistance and pumping power. Fluid flow through the solution is modeled using FNM and verified with results from the CFD analysis. In addition, CFD is employed to generate flow impedance curves of non-standard components within the cold plate, which are used as input for the Hardy Cross method in FNM. Using the verified flow network model, design parameters of different components in the cold plate are modified to promote uniform flow distribution to each active region in the chip-scale solution. Analysis of the resultant design using CFD determines additional improvement in performance over the original solution, if available. Thus, through complementary application of FNM and CFD, a robust cold plate can be designed without requiring expensive fabrication of prototypes and with minimal computational time and resources.

80 MHz Observations of the Coronal Broadening of the Crab Nebula

1970 ◽  
Vol 1 (7) ◽  
pp. 319-320 ◽  
Author(s):  
J. R. Harries ◽  
R. G. Blesing ◽  
P. A. Dennison
Keyword(s):  
Interplanetary Medium ◽  
Crab Nebula ◽  
Angular Size ◽  
Space Vehicles ◽  
Radio Sources ◽  
The Sun ◽  
Amplitude Scintillation ◽  
Interplanetary Plasma ◽  
The Crab Nebula

Regions of the interplanetary medium currently inaccessible to space vehicles may conveniently be studied using the radio scattering properties of the interplanetary plasma. These effects may give rise to angular broadening of radio sources sufficiently close to the Sun, or to amplitude scintillation of sources of small angular size.

scholarly journals Car Soundproof Improvement through an SMA Adaptive System

Actuators ◽  
2018 ◽  
Vol 7 (4) ◽  
pp. 88 ◽  
Author(s):  
Salvatore Ameduri ◽  
Angela Brindisi ◽  
Monica Ciminello ◽  
Antonio Concilio ◽  
Vincenzo Quaranta ◽  
...  
Keyword(s):  
Computer Aided Design ◽  
Adaptive System ◽  
System Development ◽  
Numerical Models ◽  
Modular System ◽  
Design Parameters ◽  
Joule Effect ◽  
Acoustic Insulation ◽  
Opening And Closing ◽  
Aided Design

The work at hand focuses on an adaptive system aimed at improving the soundproof performance of car door seals at specific regimes (cruise), without interfering with the conventional opening and closing operations. The idea addresses the necessity of increasing seal effectiveness, jeopardized by aerodynamic actions that strengthen as the speed increases, generating a growing pressure difference between the internal and the external field in the direction of opening the door, and then deteriorating the acoustic insulation. An original expansion mechanism driven by a shape memory alloy (SMA) wire was integrated within the seal cavity to reduce that effect. The smart material was activated (heated) by using the Joule effect; its compactness contributed to the realization of a highly-integrable and modular system (expanding cells). In this paper, the system development process is described together with the verification and validation activity, aimed at proving the functionality of the realized device. Starting from industrial requirements, a suitable solution was identified by considering the basic phenomenon principle and the allowable design parameters. The envisaged system was designed and its executive digital mock-up (CAD, computer-aided design) was released. Prototyping and laboratory tests showed the reliability of the developed numerical models and validated the associated predictions. Finally, the system was integrated within the reference car. To demonstrate the insulation effect, the experimental campaign was carried out in an anechoic room, achieving significant results on the concept value.

On the Amount of Dust in the Asteroid Belt

1971 ◽  
Vol 12 ◽  
pp. 389-393
Author(s):  
Fred L. Whipple
Keyword(s):  
Solar Radiation ◽  
Particle Density ◽  
Asteroid Belt ◽  
Space Vehicles ◽  
The Sun ◽  
Small Particles ◽  
Zodiacal Cloud ◽  
Upper Limit ◽  
Upper Limits

Calculations of upper limits to the quantity of small particles in the asteroid belt are based on (1) the brightness of the counterglow coupled with observations and theory for the zodiacal cloud near Earth's orbit and (2) the destruction and erosion of asteroidal particles as they spiral toward the Sun because of solar radiation via the Poynting-Robertson effect. These calculations place the likely upper limit on asteroidal space particle density at the order of 5 to 10 times and the hazard to space vehicles at 2 to 4 times those near Earth's orbit. No such evidence indicates, however, that the hazard from small particles is actually much greater in the asteroid belt.

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