scholarly journals Dynamic Optics with Transparency and Color Changes under Ambient Conditions

Polymers ◽  
2019 ◽  
Vol 11 (1) ◽  
pp. 103 ◽  
Author(s):  
Yejia Jiang ◽  
Songshan Zeng ◽  
Yu Yao ◽  
Shiyu Xu ◽  
Qiaonan Dong ◽  
...  
Keyword(s):  
Hybrid Film ◽  
Humanoid Robots ◽  
Strain Sensors ◽  
Working Environment ◽  
Practical Implementation ◽  
Ambient Conditions ◽  
Widespread Application ◽  
Smart Windows ◽  
Color Changes ◽  
Potential Applications

Mechanochromic materials have recently received tremendous attention because of their potential applications in humanoid robots, smart windows, strain sensors, anti-counterfeit tags, etc. However, improvements in device design are highly desired for practical implementation in a broader working environment with a high stability. In this article, a novel and robust mechanochromism was designed and fabricated via a facile method. Silica nanoparticles (NPs) that serve as a trigger of color switch were embedded in elastomer to form a bi-layer hybrid film. Upon stretching under ambient conditions, the hybrid film can change color as well as transparency. Furthermore, it demonstrates excellent reversibility and reproducibility and is promising for widespread application.

scholarly journals Ultra-Stretchable and Self-Healing Anti-Freezing Strain Sensors Based on Hydrophobic Associated Polyacrylic Acid Hydrogels

Materials ◽  
2021 ◽  
Vol 14 (20) ◽  
pp. 6165
Author(s):  
Shuya Yin ◽  
Gehong Su ◽  
Jiajun Chen ◽  
Xiaoyan Peng ◽  
Tao Zhou
Keyword(s):  
Flexible Electronics ◽  
Polyacrylic Acid ◽  
Retention Rate ◽  
Strain Sensors ◽  
Working Environment ◽  
Glycerol Solution ◽  
Self Healing ◽  
Ambient Conditions ◽  
Subzero Temperatures ◽  
Water Glycerol

Water-rich conductive hydrogels with excellent stretchability are promising in strain sensors due to their potential application in flexible electronics. However, the features of being water-rich also limit their working environment. Hydrogels must be frozen at subzero temperatures and dried out under ambient conditions, leading to a loss of mechanical and electric properties. Herein, we prepare HAGx hydrogels (a polyacrylic acid (HAPAA) hydrogel in a binary water–glycerol solution, where x is the mass ratio of water to glycerol), in which the water is replaced with water–glycerol mixed solutions. The as-prepared HAGx hydrogels show great anti-freezing properties at a range of −70 to 25 °C, as well as excellent moisture stability (the weight retention rate was as high as 93% after 14 days). With the increase of glycerol, HAGx hydrogels demonstrate a superior stretchable and self-healing ability, which could even be stretched to more than 6000% without breaking, and had a 100% self-healing efficiency. The HAGx hydrogels had good self-healing ability at subzero temperatures. In addition, HAGx hydrogels also had eye-catching adhesive properties and transparency, which is helpful when used as strain sensors.

Yttrium Oxyhydrides for Photochromic Applications: Correlating Composition and Optical Response

2018 ◽  
Author(s):  
Dmitrii Moldarev ◽  
Elbruz M. Baba ◽  
Marcos V. Moro ◽  
Chang C. You ◽  
Smagul Zh. Karazhanov ◽  
...  
Keyword(s):  
Medical Devices ◽  
Ternary Diagram ◽  
Optical And Electrical Properties ◽  
Ambient Conditions ◽  
Elastic Recoil ◽  
Elastic Recoil Detection Analysis ◽  
Photochromic Properties ◽  
Smart Windows ◽  
Elastic Recoil Detection ◽  
Detection Analysis

It has been recently demonstrated that yttrium oxyhydride(YHO) films can exhibit reversible photochromic properties when exposed to illumination at ambient conditions. This switchable optical propertyenables their utilization in many technological applications, such as smart windows, sensors, goggles, medical devices, etc. However, how the composition of the films affects their optical properties is not fully clear and therefore demands a straightforward investigation. In this work, the composition of YHO films manufactured by reactive magnetron sputtering under different conditions is deduced in a ternary diagram from Time-of-Flight Elastic Recoil Detection Analysis (ToF-ERDA). The results suggest that stable compounds are formed with a specificchemical formula – YH<sub>2-δ</sub>O<sub>δ</sub>. In addition, optical and electrical properties of the films are investigated, and a correlation with their compositions is established. The corresponding photochromic response is found in a specific oxygen concentration range (0.45 < δ < 1.5) with maximum and minimum of magnitude on the lower and higher border, respectively.

scholarly journals Foldable and washable textile-based OLEDs with a multi-functional near-room-temperature encapsulation layer for smart e-textiles

2021 ◽  
Vol 5 (1) ◽  
Author(s):  
So Yeong Jeong ◽  
Hye Rin Shim ◽  
Yunha Na ◽  
Ki Suk Kang ◽  
Yongmin Jeon ◽  
...  
Keyword(s):  
Room Temperature ◽  
Wearable Electronics ◽  
Ambient Conditions ◽  
Light Emitting ◽  
Stable Operating ◽  
Mechanical Durability ◽  
Potential Applications ◽  
Wearable Electronic ◽  
Data Signal ◽  
Wearable Electronic Devices

AbstractWearable electronic devices are being developed because of their wide potential applications and user convenience. Among them, wearable organic light emitting diodes (OLEDs) play an important role in visualizing the data signal processed in wearable electronics to humans. In this study, textile-based OLEDs were fabricated and their practical utility was demonstrated. The textile-based OLEDs exhibited a stable operating lifetime under ambient conditions, enough mechanical durability to endure the deformation by the movement of humans, and washability for maintaining its optoelectronic properties even in water condition such as rain, sweat, or washing. In this study, the main technology used to realize this textile-based OLED was multi-functional near-room-temperature encapsulation. The outstanding impermeability of TiO2 film deposited at near-room-temperature was demonstrated. The internal residual stress in the encapsulation layer was controlled, and the device was capped by highly cross-linked hydrophobic polymer film, providing a highly impermeable, mechanically flexible, and waterproof encapsulation.

Vanadium dioxide for thermochromic smart windows in ambient conditions

2021 ◽  
pp. 100827
Author(s):  
Nan Shen ◽  
Shi Chen ◽  
Runqing Huang ◽  
Jiaqi Huang ◽  
Jingyi Li ◽  
...  
Keyword(s):  
Vanadium Dioxide ◽  
Ambient Conditions ◽  
Smart Windows

Early Fault Detection of Hot Components in Gas Turbines

2016 ◽  
Vol 139 (2) ◽  
Author(s):  
Liu Jinfu ◽  
Liu Jiao ◽  
Wan Jie ◽  
Wang Zhongqi ◽  
Yu Daren
Keyword(s):  
Fault Detection ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Working Environment ◽  
Detection Sensitivity ◽  
Normal Operation ◽  
Large Temperature ◽  
Ambient Conditions ◽  
Fisher Discriminant Analysis ◽  
Early Fault Detection

The working environment of hot components is the most adverse of all gas turbine components. Malfunction of hot components is often followed by catastrophic consequences. Early fault detection plays a significant role in detecting performance deterioration immediately and reducing unscheduled maintenance. In this paper, an early fault detection method is introduced to detect early fault symptoms of hot components in gas turbines. The exhaust gas temperature (EGT) is usually used to monitor the performance of the hot components. The EGT is measured by several thermocouples distributed equally at the outlet of the gas turbine. EGT profile is symmetrical when the unit is in normal operation. And the faults of hot components lead to large temperature differences between different thermocouple readings. However, interferences can potentially affect temperature differences, and sometimes, especially in the early stages of the fault, its influence can be even higher than that of the faults. To improve the detection sensitivity, the influence of interferences must be eliminated. The two main interferences investigated in this study are associated with the operating and ambient conditions, and the structure deviation of different combustion chambers caused by processing and installation errors. Based on the basic principles of gas turbines and Fisher discriminant analysis (FDA), a new detection indicator is presented that characterizes the intrinsic structure information of the hot components. Using this new indicator, the interferences involving the certainty and the uncertainty are suppressed and the sensitivity of early fault detection in gas turbine hot components is improved. The robustness and the sensitivity of the proposed method are verified by actual data from a Taurus 70 gas turbine produced by Solar Turbines.

scholarly journals Pulsed Electrodeposition for Copper Nanowires

Crystals ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 218 ◽  
Author(s):  
Duc-Thinh Vuong ◽  
Ha-My Hoang ◽  
Nguyen-Hung Tran ◽  
Hyun-Chul Kim
Keyword(s):  
Sheet Resistance ◽  
Indium Tin Oxide ◽  
Transparent Electrode ◽  
Pulse Frequency ◽  
Transparent Conductors ◽  
Copper Nanowires ◽  
Ambient Conditions ◽  
Smart Windows ◽  
Promising Alternative ◽  
Flexible Polymer

Copper nanowires (Cu NWs) are a promising alternative to indium tin oxide (ITO), for use as transparent conductors that exhibit comparable performance at a lower cost. Furthermore, Cu NWs are flexible, a property not possessed by ITO. However, the Cu NW-based transparent electrode has a reddish color and tends to deteriorate in ambient conditions due to the oxidation of Cu. In this paper, we propose a pulsed-current (PC) plating method to deposit nickel onto the Cu NWs in order to reduce oxidation over a 30-day period, and to minimize the sheet resistance. Additionally, the effects of the pulse current, duty cycle, and pulse frequency on the performance of the Cu–Ni (copper–nickel) NW films have also been investigated. As a result, the reddish color of the electrode was eliminated, as oxidation was completely suppressed, and the sheet resistance was reduced from 35 Ω/sq to 27 Ω/sq. However, the transmittance decreased slightly from 86% to 76% at a wavelength of 550 nm. The Cu–Ni NW electrodes also exhibited excellent long-term cycling stability after 6000 bending cycles. Our fabricated Cu–Ni electrodes were successfully applied in flexible polymer-dispersed liquid crystal smart windows.

Advanced Multi-Cup Fuel Injector Technology for Environmentally Responsible Aviation Gas Turbine Engines

2015 ◽  
Author(s):  
Erlendur Steinthorsson ◽  
Adel Mansour ◽  
Brian Hollon ◽  
Michael Teter ◽  
Clarence Chang
Keyword(s):  
Gas Turbine ◽  
Direct Injection ◽  
Pressure Ratio ◽  
Test Facility ◽  
Turbine Engines ◽  
Practical Implementation ◽  
Gas Turbine Engines ◽  
Fuel Injector ◽  
Ambient Conditions ◽  
Environmentally Responsible

Participating in NASA’s Environmentally Responsible Aviation (ERA) Project, Parker Hannifin built and tested multipoint Lean Direct Injection (LDI) fuel injectors designed for NASA’s N+2 55:1 Overall Pressure-Ratio (OPR) gas turbine engine cycles. The injectors are based on Parker’s earlier three-zone injector (3ZI) which was conceived to enable practical implementation of multipoint LDI schemes in conventional aviation gas turbine engines. The new injectors offer significant aerodynamic design flexibility, excellent thermal performance, and scalability to various engine sizes. The injectors built for this project contain 15 injection points and incorporate staging to enable operation at low power conditions. Ignition and flame stability were demonstrated at ambient conditions with ignition air pressure drop as low as 0.3% and fuel-to-air ratio (FAR) as low as 0.011. Lean Blowout (LBO) occurred at FAR as low as 0.005 with air at 460 K and atmospheric pressure. A high pressure combustion testing campaign was conducted in the CE-5 test facility at NASA Glenn Research Center at pressures up to 250 psi and combustor exit temperatures up to 2,033 K (3,200 °F). The tests demonstrated estimated LTO cycle emissions that are about 30% of CAEP/6 for a reference 60,000 lbf thrust, 54.8-OPR engine. This paper presents some details of the injector design along with results from ignition, LBO and emissions testing.

scholarly journals Thin Film Stabilization of Different VO2 Polymorphs

2020 ◽  
Author(s):  
Manish Kumar ◽  
Chirag Saharan ◽  
Sunita Rani
Keyword(s):  
Thin Film ◽  
Growth Parameters ◽  
Chemical Properties ◽  
X Ray Diffraction ◽  
Smart Windows ◽  
Thin Film Form ◽  
Potential Applications ◽  
Vo2 Thin Films ◽  
Physical And Chemical ◽  
Film Form

In recent years, VO2 has emerged as a popular candidate among the scientific community across the globe owing to its unique technological and fundamental aspects. VO2 can exist in several polymorphs (such as: A, B, C, D, M1, M2, M3, P, R and T) which offer a broad spectrum of functionalities suitable for numerous potential applications likewise smart windows, switching devices, memory materials, battery materials and so on. Each phase of VO2 has specific physical and chemical properties. The device realization based on specific functionality call for stabilization of good quality single phase VO2 thin films of desired polymorphs. Hence, the control on the growth of different VO2 polymorphs in thin film form is very crucial. Different polymorphs of VO2 can be stabilized by selecting the growth route, growth parameters and type of substrate etc. In this chapter, we present an overview of stabilization of the different phases of VO2 in the thin film form and the identification of these phases mainly by X-ray diffraction and Raman spectroscopy techniques.

scholarly journals Mechanoresponsive scatterers for high-contrast optical modulation

Nanophotonics ◽  
2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Donghwi Cho ◽  
Haomin Chen ◽  
Jonghwa Shin ◽  
Seokwoo Jeon
Keyword(s):  
Energy Consumption ◽  
Electric Fields ◽  
Structural Parameters ◽  
Future Research ◽  
Great Promise ◽  
Design Strategies ◽  
Smart Windows ◽  
Advantages And Disadvantages ◽  
Potential Applications ◽  
External Stimuli

Abstract Smart chromatic materials with optical transmittances that can be modified by light scattering upon external stimuli are attracting extensive interest because of their appealing applications in smart windows, privacy protection, electronic displays, etc. However, the development of these scatterers, which are mostly activated by electric fields, is hindered by their intrinsic energy consumption, slow responses, and poor stability. Recently, mechanoresponsive scatterers based on a strain-driven reconfiguration of the surface or internal structure have emerged, featuring fast responses and a simple composition/fabrication. Because there is no energy consumption to maintain the transparency/opacity, this novel scheme for scatterers holds great promise to break the existing bottleneck. This article presents recent advances in the development of mechanoresponsive scatterers and compares different structural design strategies. The scatterers are categorized into 2D, 3D, and other types according to the dimensions of their functioning structures. The fabrication methods, mechanisms, and relationships between the structural parameters and optical modulating performances are discussed for each category. Next, the potential applications of these scatterers are outlined. Finally, the advantages and disadvantages of the mainstream 2D and 3D categories are summarized, followed by a perspective on future research directions.

scholarly journals Energy-Efficient Smart Window Based on Thermochromic Hydrogel with Ultrahigh Visible Transparency and Unprecedented Infrared Transmittance Modulation

2021 ◽  
Author(s):  
Rong Zhang ◽  
Bo Xiang ◽  
Min Feng ◽  
Liru Xia ◽  
Lei Xu ◽  
...  
Keyword(s):  
Energy Saving ◽  
Superior Performance ◽  
Significant Advance ◽  
Solar Modulation ◽  
Smart Window ◽  
Smart Windows ◽  
Responsive Materials ◽  
Infrared Transmittance ◽  
Potential Applications ◽  
Glass Panels

Abstract Both high visible transparency and strong solar modulating ability are highly required for energy-saving smart windows, but conventional responsive materials usually have low transparency and narrow solar transmittance range. Herein, we report a significant advance toward the design and fabrication of responsive smart windows by trapping novel V0.8W0.2O2@SiO2 doped poly(N-isopropyl acrylamide) (PNIPAm) thermochromic liquid hydrogel within two glass panels. The smart window is highly transparent to allow solar transmittance at low temperatures, while turns opaque automatically to cut off solar energy gain when exposed in sunlight. With a remarkably low content (1.0wt‰) of dopant, V0.8W0.2O2@SiO2/PNIPAm (VSP) hydrogels exhibit ultrahigh luminous transmittance Tlum of 92.48% and solar modulation ∆Tsol of 77.20%. The superior performance is mainly attributed to that V0.8W0.2O2@SiO2 doping induces PNIPAm particles’ size reduction and internal structure change. W-doping decreases the phase transition temperature (Tc) of VO2 from 68 ºC to ~30 ºC (close to the Tc of PNIPAm), contributing to an unprecedented infrared transmittance modulation. Especially, the smart window shows excellent energy-saving during daytime outdoor demonstrations where practically achievable cooling temperature reaches up to 15.1 ºC. In addition, the smart window exhibits outstanding stability, as embodied by unchanged optical performance even after 100 transparency-opaqueness reversible cycles. This new type of thermochromic hydrogel offering unique advantages of shape-independence, scalability together with soundproof functionality promises potential applications in energy-saving buildings and greenhouses.

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