scholarly journals Structural Control Aiming for High-performance SiC Polycrystalline Fiber

2016 ◽  
Vol 53 (6) ◽  
pp. 615-621 ◽  
Author(s):  
Toshihiro Ishikawa ◽  
Hiroshi Oda
Keyword(s):  
Structural Control ◽  
High Performance

A New X-Actuator Design for Controlling Wing Bending and Twisting Modes

1999 ◽  
Author(s):  
R. Ye ◽  
J. H. Ding ◽  
H. S. Tzou
Keyword(s):  
Structural Control ◽  
High Performance ◽  
Fe Method ◽  
Aerodynamic Efficiency ◽  
Aircraft Wings ◽  
Helicopter Blades ◽  
Active Structural Control ◽  
Trailing Edges ◽  
Parallel Configuration ◽  
Actuator Design

Abstract Recent development of smart structures and structronic systems has demonstrated the technology in many engineering applications. Active structural control of aircraft wings or helicopter blades (e.g., shapes, flaps, leading and/or trailing edges) can significantly enhance the aerodynamic efficiency and flight maneuverability of high-performance airplanes and helicopters. This paper in to evaluate the dual bending and torsion vibration control effects of an X-actuator configuration reconfigured from a parallel configuration. Finite element (FE) formation of a new FE using the layerwise constant shear angle theory is reviewed and the derived governing equations are discussed. Bending and torsion control effects of plates are studied using the FE method and also demonstrated via laboratory experiments. FE and experimental results both suggest the X-actuator is effective to both bending and torsion control of plates.

An Active-Passive Piezoelectric Vibration Absorber for Structural Control Under Harmonic Excitations With Time-Varying Frequency

2000 ◽  
Author(s):  
Ronald A. Morgan ◽  
K. W. Wang
Keyword(s):  
Active Control ◽  
Structural Control ◽  
High Performance ◽  
Piezoelectric Materials ◽  
Negative Resistance ◽  
Electrical Circuit ◽  
Superior Performance ◽  
Electrical Networks ◽  
Harmonic Excitations ◽  
Time Varying Frequency

Abstract It has been shown that piezoelectric materials can be used as passive electromechanical vibration absorbers when shunted by electrical networks. Semi-active piezoelectric absorbers have also been proposed for suppressing harmonic excitations with varying frequency. However, these semi-active devices have limitations that restrict their applications. The design presented here is a high performance active-passive alternative to semi-active absorbers that uses a combination of a passive electrical circuit and active control actions. The active control consists of three parts: an adaptive inductor tuning action, a negative resistance action, and a coupling enhancement action. A formulation for the optimal tuning of the piezoelectric absorber inductance on a multiple degree of freedom (MDOF) structure is derived. The effectiveness of the proposed system is demonstrated experimentally on a system under a variable frequency excitation. Extensive parameter studies are also carried out to show that the proposed design offers superior performance and efficiency compared to other state-of-the-art control methods.

Structural Control of SiOx Coatings and their Migration-Resistance Properties

2012 ◽  
Vol 200 ◽  
pp. 207-215 ◽  
Author(s):  
Fei Fei ◽  
Zheng Duo Wang ◽  
Li Zhen Yang ◽  
Zhao Li Hu ◽  
Li Jun Sang ◽  
...  
Keyword(s):  
Structural Control ◽  
High Performance ◽  
Food Packaging ◽  
Chemical Vapor ◽  
Thickness Measurement ◽  
Composition Analysis ◽  
Diethylhexyl Phthalate ◽  
Property Evaluation ◽  
Fresh Food ◽  
Migration Resistance

Diethylhexyl phthalate (DEHP) is a kind of plasticizers which is generally used in plastics packaging materials to provide the flexibility. Especially in PVC films, a large amount of DEHP used makes it possibility of the widespread usage of PVC in the fresh food packaging market. But recent researches proved that DEHP can be easily migration into food and food stimulant. It causes reproductive disorders, mutation, carcinogenicity, and other genetic toxicity to all mammals. Hence blocking the migration of DEHP from the plastic to the foods becomes very important issue for the food safety. In this work, the migration kinetics of DEHP was explored. We achieved that the migration of DEHP can be well controlled through coated nano-scale SiOxbarrier layer on the surface of PVC films, and the plasma enhanced chemical vapor deposition (PECVD) process is a very efficient way to prepare SiOxcoatings on the plastic surface. It is also noticed that there is a relationship between the migration-resistance properties and coating structure through Fourier transform infrared spectroscopy (FTIR) for the chemical composition analysis, scanning electron microscope (SEM) for the topography investigation of the coating surfaces, surface profilemeter for the thickness measurement of coatings, and high-performance liquid chromatography (HPLC) for the barrier property evaluation of coatings at last. We conclude that the coatings can perfectly block the migration of the DEHP from plastics to their contents. When the deposition conditions of SiOxcoatings were optimized, i.e. 50W of the discharge power, 4:1 of ratio of O2: HMDSO, and ca.100 nm thickness of SiOx, the 71.2% DEHP, compared to the control PVC film, was effectively barriered.

scholarly journals Lithium-Conducting Self-Assembled Organic Nanotubes

2021 ◽  
Author(s):  
Michael Strauss ◽  
Insu Hwang ◽  
Austin Evans ◽  
Anusree Natraj ◽  
Xavier Aguilar-Enriquez ◽  
...  
Keyword(s):  
Structural Control ◽  
High Performance ◽  
Electrochemical Impedance ◽  
Linear Sweep Voltammetry ◽  
Triethylene Glycol ◽  
Potential Range ◽  
Stimuli Responsive ◽  
Temperature Conductivity ◽  
Room Temperature Conductivity ◽  
Self Assembled

<p>Supramolecular polymers are compelling platforms for the design of stimuli-responsive materials with emergent functions. Here, we report the assembly of an amphiphilic nanotube for Li-ion conduction that exhibits high ionic conductivity, mechanical integrity, electrochemical stability, and solution processability. Imine condensation of a pyridine-containing diamine with a triethylene glycol functionalized isophthalaldehyde yields pore-functionalized macrocycles. Atomic force microscopy, scanning electron microscopy, and <i>in solvo</i> X-ray diffraction reveal that macrocycle protonation under their mild synthetic conditions drives assembly into high-aspect ratio (>10<sup>3</sup>) nanotubes with three interior triethylene glycol groups. Electrochemical impedance spectroscopy demonstrates that lithiated nanotubes are efficient Li<sup>+</sup> conductors, with an activation energy of 0.42 eV and a peak room temperature conductivity of 3.91 × 10<sup>-5</sup> S cm<sup>-1</sup>. <sup>7</sup>Li NMR and Raman spectroscopy demonstrate that lithiation occurs exclusively within the nanotube interior and implicates the glycol groups in facilitating efficient Li<sup>+</sup> transduction. Linear sweep voltammetry and galvanostatic lithium plating-stripping tests reveal that this nanotube-based electrolyte is stable over a wide potential range and supports long-term cyclability. These findings demonstrate how coupling synthetic design and supramolecular structural control can yield high-performance ionic transporters that are amenable to device relevant fabrication. More broadly, these results demonstrate the technological potential of chemically designed self-assembled nanotubes. </p>

Nonlinear Shape Control of Shells and Plates

1999 ◽  
Author(s):  
H. S. Tzou ◽  
Y. Bao ◽  
C. S. Chou
Keyword(s):  
Linear Theory ◽  
Structural Control ◽  
Shape Control ◽  
High Performance ◽  
Engineering Systems ◽  
Helicopter Blades ◽  
Performance Engineering ◽  
Control Concept ◽  
Shell Equations ◽  
Piezoelectric Shell

Abstract Adaptive shape control is essential in many high-performance engineering systems, such as nozzles, airplane wings, helicopter blades, etc. Recent development of smart structures and structronic systems offers new alternatives to shape control with inherent and embedded actuator components. Imposed shape control often involves large deformations implying that the conventional linear theory is no longer applicable. This study is to explore a new structural control concept based on nonlinear theories. Nonlinear piezoelectric shell equations are derived based on von Karman geometric nonlinearity. Physical significance and application are discussed. As to compare the linear and nonlinear theories, a zero-curvature shell–plate is investigated. Analytical results suggest that the linear theory is indeed invalid when large deformation shape control is considered. Differences between the two theories are presented. Control effects of the plate with polymeric and ceramic piezoelectric actuators are compared.

scholarly journals Control of Shape and Size in Iron Fluoride Porous Sub-Microspheres: Consequences for Steric Hindrance Interaction

2021 ◽  
Vol 3 ◽  
Author(s):  
Weibing Song ◽  
Hongyu Lu ◽  
Wenlong Zhao ◽  
Xiaofei Cao ◽  
Lei Yan ◽  
...  
Keyword(s):  
Porous Structure ◽  
Steric Hindrance ◽  
Structural Control ◽  
High Performance ◽  
Retention Rate ◽  
Rate Capability ◽  
Peg 400 ◽  
Excellent Electrochemical Performance ◽  
Remaining Capacity ◽  
Iron Based

Iron-based fluorides are promising alternates for advanced sodium-free battery cathodes due to their large theoretical capacity. However, the rational structural control on the iron-based fluorides toward high-performance batteries is still challenging. To this end, a controllable porous structure on FeF3·0.33H2O sub-microspheres is achieved by a polyethylene glycol (PEG)-assisted hydrothermal method via adjusting the volume of PEG-400. Experimental and molecular dynamic results verify that the formation of small amethyst-like sub-microspheres is mainly ascribed to the steric hindrance reaction of PEG-400, which makes it difficult for F− to combine with Fe3+ to form coordination bonds, and partially hinders the nucleation and growth of FeF3·0.33H2O nanospheres. As a sodium-free battery cathode, the FeF3·0.33H2O sub-microspheres with porous structure and smaller particle size exhibit excellent electrochemical performance with regard to cycle capacity and rate capability (a remaining capacity of 328 mAh g−1 and up to 95.3% retention rate when backs to 0.1 C after 60 cycles).

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