59,748 results
Search Results
2. Study on mechanical and electrical properties improvement of insulating paper modified by cellulose nanocrystals.
- Author
-
Zhang, Daning, Zhai, Xinnan, Wang, Siyu, Li, Xuan, Xu, Pengjiang, Zhao, Haoxiang, and Zhang, Guan-jun
- Subjects
YOUNG'S modulus ,DOPING agents (Chemistry) ,DIELECTRIC properties ,CONCENTRATION gradient ,SCANNING electron microscopy ,CELLULOSE nanocrystals - Abstract
The mechanical and dielectric properties of transformer insulating paper are key factors that require close attention to ensure optimal operation. In this study, a novel approach of enhancing properties by nanocellulose modification was proposed. To investigate the effect of doping, insulating paper with different doping mass fractions of cellulose nanocrystals (CNCs) was prepared, and multiple properties of the sample were characterized. By applying a doping concentration gradient, the non-monotonic trend in performance with doping levels was revealed, and the impact of doping concentration on the data variability was investigated. The effects of CNC doping on the surface pore size of the samples were analyzed by SEM (scanning electron microscopy) and a mercury intrusion method, and the regularity of CNC dispersion uniformity with doping concentration was investigated. The Brunauer, Emmett, and Teller model was employed to fit the water vapor adsorption isotherm data, providing an analysis of the impact of doping on hydrogen bond connections and the moisture adsorption properties. Tensile strength and Young's modulus were measured and analyzed using the Page model and the Halpin–Kardos model. The tensile strength of the 6 wt. % CNC-modified paper was increased by 6.91%. 10 wt. % CNC-modified paper had a Young's modulus increase of 11.98%. 3 wt. % CNC-modified paper has a 28.53% increase in the AC breakdown field strength and an 8.72% increase in the DC breakdown field strength. The influence of CNC on the dielectric properties of the insulating paper was discussed using the Havriliak–Negami (H–N) model. The results indicate that the introduction of CNC can effectively enhance the comprehensive performance of oil-immersed insulating paper. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
3. Fabrication of negative magnetostrictive Japanese traditional paper (washi) with cobalt ferrite particles.
- Author
-
Kurita, Hiroki, Rova, Lovisa, Keino, Takumi, and Narita, Fumio
- Subjects
MAGNETOSTRICTION ,FERRITES ,COBALT ,JAPANESE language ,WOOD-pulp ,CELLULOSE fibers ,MAGNETIC particles - Abstract
The cellulose fibers that form washi are longer than those of regular paper made from wood pulp. Hence, the mechanical properties of washi can be higher than those of conventional paper. This study evaluated the magnetic, magnetostrictive, and tensile properties of negative magnetostrictive cobalt ferrite (CoFe
2 O4 ) particle dispersed handmade washi (washi−CoFe2 O4 ). The CoFe2 O4 additives magnetized the washi, which displayed negative magnetostriction with the fiber direction perpendicular to the magnetic field and in the parallel fiber direction. Concerning the mechanical properties, the washi−CoFe2 O4 displayed an elongation of up to 77% after yielding. [ABSTRACT FROM AUTHOR]- Published
- 2023
- Full Text
- View/download PDF
4. Molecular simulation of different types of polysilsesquioxane doped cellulose insulating paper: A guide for special cellulose insulating paper.
- Author
-
Zeng, Zhenglin, Tan, Weimin, Deng, Yanhe, Cheng, Quan, Fu, Liuyue, and Tang, Chao
- Subjects
CELLULOSE fibers ,CELLULOSE ,GLASS transition temperature ,MODULUS of rigidity ,BULK modulus ,ELASTIC modulus ,DIELECTRIC properties - Abstract
To develop special insulating paper is of great significance to promote the service life of transformers. Using molecular simulation to guide the development of special insulating paper can greatly reduce the trial-and-error rate and waste of resources in traditional experiments. The effect of different types of polysilsesquioxane (POSS) on cellulose insulating paper was investigated by using molecular simulation. This paper investigated the thermal stability and mechanical properties and electrical characteristics of caged POSS, semi-caged POSS, and ladder-like POSS doped cellulose insulating paper. The results show that POSS with all types can enhance the performance of cellulose insulating paper, and ladder-like POSS possess the best modification effect. The glass transition temperature was increased by 58 K, and the bulk modulus, shear modulus, and elastic modulus of cellulose insulating paper doped with ladder-like POSS can improve up to 27.07%, 45.67%, and 41.28%, respectively. Meanwhile, the dielectric properties of ladder-like POSS modified insulating paper are also significantly improved. The findings of this paper propose a method for the preparation of ladder-like POSS modified insulating paper, which provides theoretical guidance for the experimental preparation of special insulating paper. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
5. Fabrication and characterization of graphene-based paper for heat spreader applications.
- Author
-
Muhsan, Ali A. and Lafdi, Khalid
- Subjects
THERMAL conductivity measurement ,THERMAL conductivity ,CHEMICAL processes ,CHEMICAL vapor deposition ,SCANNING electron microscopy ,SLURRY - Abstract
In this work, in-plane thermal conductivity measurement was carried out on graphene-based papers. Graphene-based papers were fabricated using various processing techniques such as chemical vapor deposition (CVD), hot pressing of graphene slurry, and evaporation induced self-assembly. The prepared materials were characterized using scanning electron microscopy, Raman spectroscopy, and X-ray diffraction. In-plane thermal conductivity measurement was performed via a steady state thin film thermal conductivity apparatus. The in-plane thermal conductivity measurements show that the CVD based sample has the highest thermal conductivity. COMSOL Multiphysics was used to simulate the in-plane thermal conductivity of graphene-based papers. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
6. X-ray microtomography and laser ablation in the analysis of ink distribution in coated paper.
- Author
-
Myllys, M., Häkkänen, H., Korppi-Tommola, J., Backfolk, K., Sirviö, P., and Timonen, J.
- Subjects
LASER ablation ,X-ray computed microtomography ,INK chemistry ,PERMEABILITY of paper coatings ,PROFILOMETER ,PENETRATION mechanics - Abstract
A novel method was developed for studying the ink-paper interface and the structural variations of a deposited layer of ink. Combining high-resolution x-ray tomography with laser ablation, the depth profile of ink (toner), i.e., its varying thickness, could be determined in a paper substrate. X-ray tomography was used to produce the 3D structure of paper with about 1 μm spatial resolution. Laser ablation combined with optical imaging was used to produce the 3D structure of the printed layer of ink on top of that paper with about 70 nm depth resolution. Ablation depth was calibrated with an optical profilometer. It can be concluded that a toner layer on a light-weight-coated paper substrate was strongly perturbed by protruding fibers of the base paper. Such fibers together with the surface topography of the base paper seem to be the major factors that control the leveling of toner and its penetration into a thinly coated paper substrate. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
7. Construct Schottky interface containing energy-filtering effect: An efficient strategy to decouple thermopower and conductivity.
- Author
-
Lin, Zizhen, Ping, Xiaofan, Zhao, Dongming, Wang, Lichuang, Li, Menglei, Cai, Zihe, Zhang, Yun, Li, Xinlian, and Zhang, Xuankai
- Subjects
THERMOELECTRIC power ,THERMOELECTRIC materials ,IMPURITY centers ,ELECTRIC conductivity ,CHARGE carriers ,SEEBECK coefficient ,FILTERS & filtration - Abstract
Organic/inorganic thermoelectric hybrids demonstrate great potential for wearable applications. However, their scalability is hindered by an inferior power factor (S 2 σ). Nowadays, achieving deep optimization of S 2 σ necessitates a strategy to decouple the Seebeck coefficient (S) and electrical conductivity (σ). In this work, we propose a strategy to break the coupling between S and σ by constructing a Schottky interface that exhibits an energy-filtering effect. We validate the feasibility of this approach using a PANI/TiN–TiO
2 /carbon paper. The results demonstrate a 1.16-fold increase in σ and a 1.08-fold increase in S in PANI/TiN–TiO2 /carbon paper achieved through the construction of a Schottky-type TiN/TiO2 interface. The separation of hole/electron at the TiN/TiO2 interface serves as the scattering center for ionized impurity scattering and facilitates the transport pathway for charge carriers. These factors are crucial in determining the simultaneous optimization of S and σ , respectively. Additionally, the energy-filtering effect of the TiN/TiO2 interface plays a positive role in the ionized impurity scattering mechanism by selectively filtering out low-energy carriers. This further strengthens decoupling of the thermoelectric properties. The 14.9% PANI/11.2% TiN–14.5% TiO2 /59.44% carbon paper displays the highest S 2 σ and achieves a high ZT value of 223.6 μVm−1 K−2 and 0.31 at 300 K, highlighting the advantages of PANI-based thermoelectric hybrids. This work provides valuable guidance for the design of thermoelectric hybrids incorporating multi-interface morphology. [ABSTRACT FROM AUTHOR]- Published
- 2023
- Full Text
- View/download PDF
8. Reactive molecular dynamics research on influences of water on aging characteristics of PMIA insulation paper.
- Author
-
Wang, Lihan, Yin, Fei, Shen, Yin, and Tang, Chao
- Subjects
MOLECULAR dynamics ,INSULATING oils ,CHEMICAL stability ,HYDROXYL group ,ACTIVATION energy ,MOISTURE content of food - Abstract
The diffusion of moisture in the meta-aramid fiber (PMIA) oil-paper insulation system and the thermal decomposition of PMIA insulation paper in different moisture contents were studied via molecular dynamics simulations. The results showed that the PMIA insulation paper had a stronger ability to absorb water molecules than the insulating oil; therefore, water molecules in the insulating oil diffuse to the insulation paper, which further affects the thermal decomposition of the PMIA insulation paper. The activation energy of the water-bearing composite model was 129.96 kJ/mol, which was 5.5% lower than that of the pure PMIA (137.61 kJ/mol). It indicated that moisture could promote PMIA decomposition. The micromechanism of the enhanced thermal decomposition of PMIA with moisture contents could be described as follows: The O–H bond of the water can easily break to generate H atoms and hydroxyl radicals (
• OH). The strong activity of H atoms allows it to easily combine with the ammonia base at the end of PMIA to generate NH3 . Additionally, the free• OH radical can easily combine with the amido and carbonyl bonds at two ends of PMIA, undergo an oxidation reaction, and generate an oxhydryl. Therefore, it can reduce the chemical stability of the PMIA chain and further drive thermal decomposition. Statistical data on fragments generated by the thermal decomposition of the water-bearing PMIA composite system show that the main products include H2 , C/H/O-containing molecules, hydrocarbon molecules, N-bearing molecules, and free radicals. [ABSTRACT FROM AUTHOR]- Published
- 2020
- Full Text
- View/download PDF
9. Temperature-dependence of electrical and dielectric properties of papers for electrophotography.
- Author
-
Maldzius, R., Sirviö, P., Sidaravicius, J., Lozovski, T., Backfolk, K., and Rosenholm, J. B.
- Subjects
ELECTROPHOTOGRAPHY ,PRINTING ,PHOTORECEPTORS ,ELECTRIC fields ,ELECTRIC conductivity ,TEMPERATURE - Abstract
The temperature-dependence of the electrical and dielectric properties of paper substrates was studied using experimental papers with different NaCl contents, different thicknesses, and different grammages. Physical processes related to the charging potential, charge decay rate, conductivity, dielectric constant, and dielectric loss of papers are dependent on thermal energy, and this dependence on temperature can be described by exponential expressions. The ion content of paper not only determines the level of these properties at a given temperature, as expected but also influences their temperature-dependence. Frequency analysis of the dielectric loss confirms that new structures are formed in paper by the addition of NaCl. The results may be applicable to the design of materials and equipment, e.g., for the electrophotographic printing processes. [ABSTRACT FROM AUTHOR]
- Published
- 2010
- Full Text
- View/download PDF
10. X-ray texture analysis of paper coating pigments and the correlation with chemical composition analysis.
- Author
-
Roine, J., Tenho, M., Murtomaa, M., Lehto, V.-P., and Kansanaho, R.
- Subjects
SURFACES (Technology) ,PRINTING properties of paper ,PRINTING equipment ,X-ray spectroscopy ,SURFACE coatings - Abstract
The present research experiments the applicability of x-ray texture analysis in investigating the properties of paper coatings. The preferred orientations of kaolin, talc, ground calcium carbonate, and precipitated calcium carbonate particles used in four different paper coatings were determined qualitatively based on the measured crystal orientation data. The extent of the orientation, namely, the degree of the texture of each pigment, was characterized quantitatively using a single parameter. As a result, the effect of paper calendering is clearly seen as an increase on the degree of texture of the coating pigments. The effect of calendering on the preferred orientation of kaolin was also evident in an independent energy dispersive spectrometer analysis on micrometer scale and an electron spectroscopy for chemical analysis on nanometer scale. Thus, the present work proves x-ray texture analysis to be a potential research tool for characterizing the properties of paper coating layers. [ABSTRACT FROM AUTHOR]
- Published
- 2007
- Full Text
- View/download PDF
11. Thin film versus paper-like reduced graphene oxide: Comparative study of structural, electrical, and thermoelectrical properties.
- Author
-
Okhay, Olena, Gonçalves, Gil, Tkach, Alexander, Dias, Catarina, Ventura, Joao, da Silva, Manuel Fernando Ribeiro, Valente Gonçalves, Luís Miguel, and Titus, Elby
- Subjects
GRAPHENE oxide ,THIN films ,CHEMICAL reduction ,HYDRAZINE ,SEMICONDUCTORS - Abstract
We report fabrication of reduced graphene oxide (rGO) films using chemical reduction by hydrazine hydrate and rGO paper-like samples using low temperature treatment reduction. Structural analysis confirms the formation of the rGO structure for both samples. Current-voltage (I-V) measurements of the rGO film reveal semiconductor behavior with the maximum current value of ~3×10
-4 A. The current for the rGO paper sample is found to be, at least, one order of magnitude higher. Moreover, bipolar resistance switching, corresponding to memristive behavior of type II, is observed in the I-V data of the rGO paper. Although precise values of the rGO film conductivity and the Seebeck coefficient could not be measured, rGO paper shows an electrical conductivity of 6.7×102 S/m and Seebeck coefficient of -6μV/°C. Thus, we demonstrate a simplified way for the fabrication of rGO paper that possesses better and easier measurable macroscopic electrical properties than that of rGO thin film. [ABSTRACT FROM AUTHOR]- Published
- 2016
- Full Text
- View/download PDF
12. Electrically and magnetically dual-driven Janus particles for handwriting-enabled electronic paper.
- Author
-
Komazaki, Y., Hirama, H., and Torii, T.
- Subjects
JANUS particles ,ELECTRONIC paper ,MICROFLUIDIC analytical techniques ,SUPERPARAMAGNETIC materials ,NANOPARTICLES ,ELECTRIC potential ,MAGNETIC fields ,INTERNET forums - Abstract
In this work, we describe the synthesis of novel electrically and magnetically dual-driven Janus particles for a handwriting-enabled twisting ball display via the microfluidic technique. One hemisphere of the Janus particles contains a charge control agent, which allows the display color to be controlled by applying a voltage and superparamagnetic nanoparticles, allows handwriting by applying a magnetic field to the display. We fabricated a twisting ball display utilizing these Janus particles and tested the electric color control and handwriting using a magnet. As a result, the display was capable of permitting handwriting with a small magnet in addition to conventional color control using an applied voltage (80 V). Handwriting performance was improved by increasing the concentration of superparamagnetic nanoparticles and was determined to be possible even when 80V was applied across the electrodes for 4 wt.% superparamagnetic nanoparticles in one hemisphere. This improvement was impossible when the concentration was reduced to 2 wt.% superparamagnetic nanoparticles. The technology presented in our work can be applied to low-cost, lightweight, highly visible, and energy-saving electronic message boards and large whiteboards because the large-size display can be fabricated easily due to its simple structure. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
13. Radiation effects in single-walled carbon nanotube papers.
- Author
-
Cress, Cory D., Schauerman, Christopher M., Landi, Brian J., Messenger, Scott R., Raffaelle, Ryne P., and Walters, Robert J.
- Subjects
CARBON nanotubes ,NANOTUBES ,IONIZING radiation ,RADIATION ,NANOSTRUCTURES - Abstract
The effects of ionizing radiation on the temperature-dependent conductivity of single-walled carbon nanotube (SWCNT) papers have been investigated in situ in a high vacuum environment. Irradiation of the SWCNT papers with 4.2 MeV alpha particles results in a steady decrease in the SWCNT paper conductivity, resulting in a 25% reduction in room temperature conductivity after a fluence of 3×10
12 alpha particles/cm2 . The radiation-induced temperature-dependent conductivity modification indicates that radiation damage causes an increase in the effective activation barrier for tunneling-like conductivity and a concomitant increase in wavefunction localization of charge carriers within individual SWCNTs. The spatial defect generation within the SWCNT paper was modeled and confirms that a uniform displacement damage dose was imparted to the paper. This allows the damage coefficient (i.e., differential change in conductivity with fluence) for alpha particles, carbon ions, and protons to be compared with the corresponding nonionizing energy loss (NIEL) of the incident particle. The resulting nonlinear relationship with NIEL between these parameters is distinct from the more typical linear response observed in many bulk semiconductors and superconductors and indicates that localized radiation damage in the SWCNT papers has a greater impact than distributed damage. Although SWCNT papers behave largely as a bulk material with properties that are a convolution of the underlying SWCNT distribution, the radiation response appears to be largely dominated by degradation in the preferred one-dimensional conduction within these two-dimensionally confined nanostructures. [ABSTRACT FROM AUTHOR]- Published
- 2010
- Full Text
- View/download PDF
14. Mechanism study of the conductivity characteristics of cellulose electrical insulation influenced by moisture.
- Author
-
Zhao, Haoxiang, Mu, Haibao, Zhang, Daning, Baumeier, Björn, Yao, Huanmin, Guo, Guangzhi, and Zhang, Guanjun
- Subjects
ELECTRIC insulators & insulation ,FRONTIER orbitals ,MOLECULAR dynamics ,CELLULOSE ,ELECTRIC distortion ,MOISTURE ,CELLULOSE synthase ,SILICONE rubber - Abstract
Cellulose insulating paper is widely used in the power industry for its good electrical insulating properties. Moisture sharply increases its conductivity, which directly leads to the weakening of insulation performance and greatly increases the risk of subsequent electric field distortion and insulation breakdown. This paper focuses on the microscopic mechanism of moisture changing the characteristics of charge transport in cellulose insulation and attempts to reveal the related conductivity mechanism. To achieve this purpose, microscopic and macroscopic perspectives are integrated and several simulation and experimental methods are utilized comprehensively. The molecular dynamics simulation results showed that most water molecules in damped cellulose were individually and uniformly adsorbed on the hydroxyl groups by hydrogen bond, and the quantum chemistry computation results showed that the lowest unoccupied molecular orbital more appeared on the water molecule and the corresponding density of state increased. Then, experimentally, it was confirmed that the trap energy level decreased by the thermally stimulated current method. On this basis, the promotion effect of moisture on charge transport is predicted and verified by polarization and depolarization current methods. As the moisture content increased, more charge carriers escaped from the trap by hopping and participated in long-range continuous charge motion. Therefore, after dampness, the current of cellulose insulating paper increased exponentially with the increase in electric field strength, which was consistent with the hopping conductivity mechanism. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
15. Electronic structure spectroscopy of organic semiconductors by energy resolved-electrochemical impedance spectroscopy (ER-EIS).
- Author
-
Schauer, Franz
- Subjects
ORGANIC semiconductors ,ELECTRONIC structure ,IMPEDANCE spectroscopy ,SEMICONDUCTOR materials ,MATERIALS science ,FULLERENES ,ELECTRONIC paper ,TIME-resolved spectroscopy - Abstract
Organic electronic applications are envisioned to address broad markets, which includes flexible displays, electronic papers, sensors, disposable and wearable electronics, and medical and biophysical applications, leading to a tremendous amount of interest from both academia and industry in the study of devices. These fields of science and technology constitute interdisciplinary fields that cover physics, chemistry, biology, and materials science, leading, as a wanted output, to the elucidation of physical and chemical properties, as well as structures, fabrication, and performance evaluation of devices and the creation of new knowledge underlying the operation of organic devices using new synthesized organic materials—organic semiconductors. We testify the situation when the available organic electronic applications sometimes lack a theoretical background. The cause may be the complicated properties of disordered, weak bounded, molecular materials with properties different from their inorganic counterparts. One of the basic information-rich resources is the electronic structure of organic semiconductors, elucidated by the methods, hardly possible to be transferred from the branch of inorganic semiconductors. Electrochemical spectroscopic methods, in general, and electrochemical impedance spectroscopy, in particular, tend and seem to fill this gap. In this Perspective article, the energy resolved-electrochemical impedance spectroscopic method for electronic structure studies of surface and bulk of organic semiconductors is presented, and its theoretical and implementation background is highlighted. To show the method's properties and strength, both as to the wide energy and excessive dynamic range, the basic measurements on polymeric materials and D–A blends are introduced, and to highlight its broad applicability, the results on polysilanes degradability, gap engineering of non-fullerene D–A blends, and electron structure spectroscopy of an inorganic nanocrystalline film are highlighted. In the outlook and perspective, the electrolyte/polymer interface will be studied in general and specifically devoted to the morphological, transport, and recombination properties of organic semiconductors and biophysical materials. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
16. Thermophysical characterization of artificially aged papers by means of the photothermal...
- Author
-
Bertolotti, M. and Ligia, S.
- Subjects
PAPER ,THERMOPHYSICAL properties - Abstract
Presents information on a study which determined the thermophysical properties of artificially aged paper samples by means of photothermal deflection technique. Theory; Experimental results and discussion; Conclusions.
- Published
- 1999
- Full Text
- View/download PDF
17. Improvements of mechanical properties of multilayer open-hole graphene papers.
- Author
-
Xia, Yuxuan, Li, Yeyuan, Zhu, Chunhua, Wei, Ning, and Zhao, Junhua
- Subjects
SHEAR strength ,CARBON-carbon bonds ,TENSILE strength ,STRESS concentration ,COVALENT bonds ,LAMINATED glass - Abstract
Holes and defects can greatly reduce the mechanical properties of multilayer graphene sheets under different loading conditions due to the stress concentration near the hole edge in each in-plane sheet and the lack of interlayer carbon–carbon bonds between the layers. Here, we report a novel design of multilayer open-hole graphene papers (MLGPs) formed through interlayer covalent bonding at the hole edges of multilayer open-hole graphene sheets (MLGSs) under high temperature using molecular dynamics (MD) simulations. Our MD results show that the hybrid sp
2 –sp3 interlayer bonds of MLGPs can significantly improve their both tensile strength and interlayer shear strength. The tensile strength and interlayer shear strength of MLGPs increase by around 20% and 3 times by comparison with those of MLGSs with the same number of layers, respectively, which mainly depends on the uniformity of their interlayer bond distribution. This study can provide an effective way to improve the mechanical performances of multilayer graphene sheets with flaws and also offer corresponding guidance for the design of MLGS-based nanocomposites. [ABSTRACT FROM AUTHOR]- Published
- 2019
- Full Text
- View/download PDF
18. Dynamic Measurements of Physical Properties of Pulp and Paper by Audiofrequency Sound.
- Author
-
Horio, M. and Onogi, S.
- Published
- 1951
- Full Text
- View/download PDF
19. Physics in The Paper Industry.
- Author
-
Samson, E. W.
- Published
- 1937
- Full Text
- View/download PDF
20. Electrical conductivity of carbon-nanotube/cellulose composite paper.
- Author
-
Tanaka, Tomo, Sano, Eiichi, Imai, Masanori, and Akiyama, Kousuke
- Subjects
CARBON nanotubes ,NANOTUBES ,ELECTRIC conductivity research ,CELLULOSE ,COMPOSITE materials ,QUANTUM tunneling ,MATHEMATICAL models - Abstract
We fabricated multiwalled carbon-nanotube/cellulose composite papers and measured their temperature dependences of electrical conductivity. The dependences were described with the Sheng’s fluctuation-induced tunneling (FIT) model. A possible mechanism of the electrical conduction in the composite paper was discussed in the context of the FIT model. [ABSTRACT FROM AUTHOR]
- Published
- 2010
- Full Text
- View/download PDF
21. Paper-based ultracapacitors with carbon nanotubes-graphene composites.
- Author
-
Jian Li, Xiaoqian Cheng, Jianwei Sun, Brand, Cameron, Shashurin, Alexey, Reeves, Mark, and Keidar, Michael
- Subjects
SUPERCAPACITORS ,CARBON nanotubes ,GRAPHENE ,SCANNING electron microscopes ,TRANSMISSION electron microscopes ,RAMAN spectroscopy ,THIN films - Abstract
In this paper, a paper-based ultracapacitors were fabricated by the rod-rolling method with the ink of carbon nanomaterials, which were synthesized by arc discharge under various magnetic conditions. Composites of carbon nanostructures, including high-purity single-walled carbon nanotubes (SWCNTs) and graphene flakes were synthesized simultaneously in a magnetically enhanced arc. These two nanostructures have promising electrical properties and synergistic effects in the application of ultracapacitors. Scanning electron microscope, transmission electron microscope, and Raman spectroscopy were employed to characterize the properties of carbon nanostructures and their thin films. The sheet resistance of the SWCNT and composite thin films was also evaluated by four-point probe from room temperature to the cryogenic temperature as low as 90 K. In addition, measurements of cyclic voltammetery and galvanostatic charging/discharging showed the ultracapacitor based on composites possessed a superior specific capacitance of up to 100 F/g, which is around three times higher than the ultracapacitor entirely fabricated with SWCNT. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
- View/download PDF
22. Study on the response of the winding direction of multi-layer CORC cable to its electromagnetic characteristics.
- Author
-
Jia, Rongli, Zhou, Wenhai, Liang, Rui, Su, Bingxu, and Hu, Zongwu
- Subjects
HIGH temperature superconductors ,CABLES ,STRAINS & stresses (Mechanics) ,ELECTROMAGNETIC fields ,ADHESIVE tape ,MAGNETIC fields ,ATHLETIC tape - Abstract
A Conductor on Round Core (CORC) cable wound with a high-temperature superconductor is an important cable concept for high-current density applications. It is widely used in large power systems because of its advantages of good flexibility and high engineering current density. However, the complex design structure of CORC cable makes it very difficult to understand its electromagnetic properties (such as AC loss). In particular, the different winding directions of each layer in multi-layer cable have a great influence on its electromagnetic characteristics. In this paper, the H-method is used to solve the electromagnetism and mechanics equations. The influence of the winding direction of CORC cable on its electromagnetic field distribution characteristics, AC loss, and mechanical variation under the action of external magnetic field is investigated. The AC loss study of single-layer cable reveals that when the applied magnetic field is increased from 0.01 to 0.02 and 0.03 T, the AC loss peak of the cable increases by 10
7 and 103 orders of magnitude, respectively, indicating that the effect of low applied magnetic field on the AC loss of the cable is more significant. For multi-layer cables, cables with opposite winding directions have a greater depth of current density penetration than cables with the same winding direction. In addition, the mechanical variations of multi-layer cables with different winding orientations are explored. The results show that the Mises stress in the cable with the same winding direction is about 32% higher than that of the cable with the opposite winding direction, which indicates that the method of winding the cable in the opposite direction between adjacent layers of tape can avoid excessive mechanical stress. [ABSTRACT FROM AUTHOR]- Published
- 2024
- Full Text
- View/download PDF
23. Development of a differential photoacoustic system for the determination of the effective water diffusion and water vapor permeability coefficients in thin films.
- Author
-
Martinez-Munoz, P. E., Martinez-Hernandez, H. D., Rojas-Beltran, C. F., Perez-Ospina, J. L., and Rodriguez-Garcia, M. E.
- Subjects
THIN films ,PERMEABILITY ,WATER vapor ,HUMIDITY ,ELECTRONIC noise ,DIFFUSION coefficients ,RESERVOIRS - Abstract
This paper focused on developing a methodology and metrology using a differential photoacoustic (PA) system to determine the effective water vapor diffusion coefficient (D e f f ) and the effective permeability coefficient (Π) in thin films as a piece of paper and standard polystyrene for a controlled relative humidity. The methodology proposes a new differential photoacoustic system, including the water reservoir, relative humidity, and temperature detectors. Two cells, reference/sample, were used to obtain the instrumental function to reduce the electronic and environmental noises. A method based on the study of ln [ 1 − (S − S 0) / Δ S ] = t / τ D and the behaviors of R
2 as a function of the number of data was proposed to assess the region in which the photoacoustic signal should be processed to determine each effective coefficient. S is the amplitude of the PA signal, S 0 is the initial amplitude value, Δ S is the change, t (time), and τ D is the water vapor diffusion time. The effective water diffusion coefficient (D e f f ) for water and polystyrene was 1.90 × 10−11 m2 /s and 3.09 × 10−11 m2 /s, respectively. The permeability coefficient value for the piece of paper was 4.18 × 10−9 mol kg−1 cm−2 s−1 Pa−1 , while for polystyrene, it was 6.80 × 10−9 mol kg−1 cm−2 s−1 Pa−1 for 70% of relative humidity. This methodology can be extended by changing the moisture content on the chamber to obtain the dependence of D e f f as a function of relative humidity. [ABSTRACT FROM AUTHOR]- Published
- 2022
- Full Text
- View/download PDF
24. Microwave driven atmospheric water harvesting with common sorbents.
- Author
-
Nepal, Suman, Shahrokhian, Aida, and King, Hunter
- Subjects
WATER harvesting ,SORBENTS ,MASS transfer ,MICROWAVES ,HUMIDITY ,MICROWAVE heating ,SORPTION - Abstract
Using sorbent materials to separate and concentrate ambient humidity is a promising option for atmospheric water harvesting in the face of impending worldwide freshwater scarcity. The method of cycled sorption and forced release can facilitate efficient condensation, but performance strongly depends on device-scale issues of heat and mass transfer. We examine the potential of using microwave radiation to liberate sorbed vapor, in proof-of-concept experiments with hygroscopic salt-infused paper towel as simple sorbents. We quantify performance as a function of tunable system parameters and ambient humidity. Our results demonstrate promising aspects: both rapid desorption and regeneration, owing to water-tuned dielectric heating and directing flow through fibrous sorbent, respectively; substantial efficiency of moisture separation toward very low (∼ 25 %) relative humidity; and robust repeatability over many cycles, due to the targeted energy input and retention of hygroscopic salt within the paper scaffold. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
25. Advanced mechanical properties of graphene paper.
- Author
-
Bei Wang, Xiaoping Shen, Guoxiu Wang, and Ranjbartoreh, Ali R.
- Subjects
GRAPHENE ,CARBON steel ,MICROMECHANICS ,STRAINS & stresses (Mechanics) ,STRENGTH of materials ,CARBON - Abstract
Graphene paper (GP) has been prepared by flow-directed assembly of graphene nanosheets. The mechanical properties of as-prepared GPs were investigated by tensile, indentation, and bending tests. Heat treated GPs demonstrate superior hardness, ten times that of synthetic graphite, and two times that of carbon steel; besides, their yielding strength is significantly higher than that of carbon steel. GPs show extremely high modulus of elasticity during bending test; in the range of a few terapascal. The high strength and stiffness of GP is ascribed to the interlocking-tile microstructure of individual graphene nanosheets in the paper. These outstanding mechanical properties of GPs could lead to a wide range of engineering applications. [ABSTRACT FROM AUTHOR]
- Published
- 2011
- Full Text
- View/download PDF
26. Phase field study on electrical treeing under combined AC/DC voltage based on bipolar barrier transfer model.
- Author
-
Shang, Gaoyi, Sun, Yingman, Chen, Ming, Shao, Yuhang, Li, Minjie, Tang, Hao, Li, Xining, and Liu, Xuandong
- Subjects
TREES (Electricity) ,SPACE charge ,VOLTAGE ,INSULATING materials ,ELECTRONIC equipment ,DIELECTRIC breakdown ,PARTIAL discharges - Abstract
The study of insulation degradation processes is crucial for the reliable operation of power equipment and electronic devices. The phase field method has been widely used in recent years to simulate the degradation process of insulation materials. However, the effect of space charge was ignored. In this paper, a novel phase field method based on the bipolar carrier transfer model is suggested. This model can simulate degradation under different temperatures and DC or combined AC/DC voltage. The cases under AC and combined AC/DC voltage at different temperatures are simulated by COMSOL. Methods to ensure model convergence are proposed. The results show that the field strength distribution under a combined AC/DC field is more uniform, especially for negative polarity. For the same voltage form, temperature and breakdown time show an exponential relationship. The results are consistent with those of previous experimental studies, proving the usability of the model. In addition, the processes of initiation, growth, and breakdown stage of the dielectric degradation process, as well as the stagnation period, are explored theoretically. The stagnation time at low temperatures under combined AC/negative DC voltage is long. The research in this paper is useful for insulation optimization design, condition assessment, and longevity prediction. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
27. Understanding ac losses in CORC cables of YBCO superconducting tapes by numerical simulations.
- Author
-
Nguyen, Linh N., Shields, Nathaniel, Ashworth, Stephen, and Nguyen, Doan N.
- Subjects
SUPERCONDUCTING coils ,SUPERCONDUCTING cables ,HIGH temperature superconductors ,CABLES ,FINITE element method ,COMPUTER simulation ,ADHESIVE tape ,CURRENT distribution - Abstract
Alternating current (ac) losses in conductor-on-rounded-core (CORC) cables of YBCO high-temperature superconducting (HTS) tapes are a significant challenge in HTS power applications. This study employs two finite element analysis (FEA) models to investigate the contributions from different ac loss components and provide approaches for reducing ac losses in cables. An FEA model based on the T-A formulation treats the cross section of thin superconducting layers as 1D lines and, therefore, only can predict the ac loss generated by the perpendicular magnetic field. In contrast, the model based on H-formulation can be performed on the actual 2D rectangular cross section HTS tapes to provide the total ac losses generated by magnetic fluxes penetrating from both the edges and surfaces of HTS tapes, although this model requires more computing time and memory. The 1D and 2D simulation models were validated by cross comparing the results from both models and by comparing sub-section and full cross section models. Subsequently, two models relate cable design and operational parameters to the surface and edge losses of a two-layer CORC cable by considering the (1) relative contributions of edge and surface losses to the overall ac losses; (2) effect of the current distribution between inner and outer HTS layers on ac losses; (3) impact of the tape alignment on ac losses in each HTS layer; (4) influence of the thickness of HTS layers on ac losses; (5) effect of size and number of inter-tape gaps on ac losses; and (6) contribution frequency on the ac losses. The research results given in this paper are therefore not only valuable to suggest strategies for reducing ac loss in multi-layer cables but also for developing more accurate and effective methods to calculate ac loss in CORC HTS cables. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
28. Comment on "Transverse vibration analysis of single-layered graphene sheet under magneto-thermal environment based on non-local plate theory [J. Appl. Phys. 116(16), 164303 (2014)]" and "Nonlocal elasticity based magnetic field affected vibration response of double single-walled carbon nanotube systems [J. Appl. Phys. 111(11), 113511 (2012)]"
- Author
-
Sinha, Rakesh and Mishra, Ankit
- Subjects
DOUBLE walled carbon nanotubes ,MAXWELL equations ,MAGNETIC fields ,CARBON nanotubes ,IRON & steel plates ,LORENTZ force - Abstract
The impact of a time-varying external magnetic field on carbon nanotubes has been studied using Maxwell's equations in the mentioned articles. However, the Maxwell's equations are erroneously presented in the papers. The incorrect Maxwell's equations, their derivatives, and the Lorentz force equations have all been examined in this work. In this article, we have endeavored to ensure that the equations are formatted correctly and have made an effort to do so. We have made an effort to intuitively correct the equations' errors. We did not comment on the other portions of the mentioned articles; instead, we restricted ourselves to the examination of the impact of Maxwell's equations and Lorentz force equations. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
29. The Theory of Extreme Values and Its Implications in the Study of the Dielectric Strength of Paper Capacitors.
- Author
-
Epstein, Benjamin and Brooks, Hamilton
- Published
- 1948
- Full Text
- View/download PDF
30. Multiband topological acoustic waveguide with multistage toroidal resonant cavities.
- Author
-
Zhang, Zhi, Liang, Xiao, Chu, Jiaming, Luo, Jiangxia, Meng, Daxiang, and Zhou, Zhuo
- Subjects
TRANSMISSION of sound ,ACOUSTIC waveguides ,SOUND waves ,TOPOLOGICAL insulators ,ACOUSTICS - Abstract
In recent years, there has been significant development in acoustic waveguides through the introduction of topological phase correlation concepts in acoustics. Many studies have shown the properties of acoustic unidirectional transmission. This paper presents a new ring-shaped acoustic topological insulator that is multi-band, unlike previous structures. The structure improves internal space utilization with the same dimensions, reducing acoustic wave conduction frequency in air environments. Additionally, the introduction of a multistage ring-shaped resonant cavity enables the conduction of acoustic waves in multiple frequency bands. This paper employs the rotational scattering mechanism to invert the topological phase of the lattice. This allows for the construction of two crystals with opposite phases, which can be used to create a topological channel for the transmission of acoustic waves. At the topological interface, the acoustic transmission losses within the four bands are small. Furthermore, this paper verifies by simulation that the defects have little effect on acoustic transmission. The paper's research offers potential for multiband acoustic control. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
31. Hydrodynamic simulation of laser ablation with electronic entropy effects included.
- Author
-
Watanabe, Shuto, Akashi, Ryosuke, Ishikawa, Takahiro, Tanaka, Yuta, and Tsuneyuki, Shinji
- Subjects
ULTRA-short pulsed lasers ,POLAR effects (Chemistry) ,HOT carriers ,MELTING points ,LASER ablation ,ULTRASHORT laser pulses - Abstract
In this paper, we present a methodology of laser ablation simulation including electronic entropy effects. Ablation by ultrashort laser pulses is suitable for micromachining because of its small thermal damage. To further enhance its effectiveness, it is crucial to explore both theoretically and experimentally the desirable conditions for processing. The density functional theory calculations predict that hot electrons make crystalline lattice thermodynamically unstable at electronic temperature roughly above 20 000 K due to the electronic entropy-driven mechanism. In our simulations, equations combining hydrodynamic equations and the two-temperature model are modeled and are numerically solved, where the electronic entropy effects are included as the electronic temperature-dependent latent heat, boiling point, and melting point. For metal targets, Al and Cu, the calculated ablation rates for 100 fs laser pulses agree with the experimental one at laser fluences up to 10 J/cm 2. The heat-affected zone (HAZ) is numerically evaluated from the thickness of the molten layer. Short pulses produce a high ablation rate and small HAZ because of the suppression of diffusion of the deposited pulse energy. Electronic entropy effects make a clear difference between 100 fs and 10 ps pulses. The calculation method presented in this paper serves as a useful tool for exploring nonequilibrium between electrons and ions in the equation of states for metals such as Al and Cu. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
32. Ab initio calculations of structural stability, thermodynamic and elastic properties of Ni, Pd, Rh, and Ir at high pressures.
- Author
-
Smirnov, N. A.
- Subjects
THERMODYNAMICS ,AB-initio calculations ,ELASTICITY ,STRUCTURAL stability ,BODY centered cubic structure - Abstract
This paper presents results of a comprehensive study from first principles into the properties of Ni, Pd, Rh, and Ir crystals under pressure. We calculated elastic constants, phonon spectra, isotherms, Hugoniots, sound velocities, relative structural stability, and phase diagrams. It is shown that in nickel and palladium under high pressures (>0.14 TPa) and temperatures (>4 kK), the body-centered cubic structure is thermodynamically most stable than of the face-centered cubic one. Calculated results suggest that nickel under Earth-core conditions (P ∼ 0.3 TPa, T ∼ 6 kK) have a bcc structure. No structural changes were found to occur in Rh and Ir under pressures to 1 TPa at least. This paper also provides estimations for the pressure and temperature at which the metals of interest begin to melt under shock compression. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
33. Modeling of electromechanical behavior of chitosan-blended cellulose electroactive paper (EAPap).
- Author
-
Jang, Sang-Dong, Kim, Joo-Hyung, and Kim, Jaehwan
- Subjects
CHITOSAN ,CELLULOSE ,ELECTRIC fields ,ACTUATORS ,BENDING (Metalwork) ,IONS - Abstract
Electromechanical bending actuation of chitosan-blended cellulose (CBC) electroactive paper (EAPap) was studied using a theoretical model, followed by an experimental comparison. The bending displacement of the model was calculated based on an ion traveling phenomenon and multilayered cantilever beam. By comparing the bending model and experimental data, we found that the bending model could predict the electromechanical actuation behavior as well as redistribution of ions inside of CBC EAPap under different humidity levels and electric fields. The bending actuation model of EAPap can be useful to investigate the electromechanical actuation behavior of EAPap devices such as artificial muscles, microrobots, and other various actuators. [ABSTRACT FROM AUTHOR]
- Published
- 2009
- Full Text
- View/download PDF
34. Simulation studies of internal mechanisms in the static deflection of a cellulose electroactive paper actuator.
- Author
-
Joshi, R. P., Mbaye, F., Basappa, P., Jang, S. D., Kim, J., and Hall, J. C.
- Subjects
HUMIDITY ,ABSORPTION ,STRAINS & stresses (Mechanics) ,PROPERTIES of matter ,DYNAMICS ,PHYSICS - Abstract
Studies of voltage-induced deflections in electroactive paper (EAPap) have been carried out. On the experimental side, measurements of bias-dependent deflections and strain, water absorption as a function of time, and relative humidity were obtained for the cellulose EAPap actuator. In addition, model simulations have also been carried out to probe and quantify the role of the various internal mechanisms responsible for the deflection. Our simulation predictions yield good agreement with the measured deflection data for the EAPap. The modeling suggests that internal ion content and its migration, water absorption leading to a nonuniform permittivity, random variations in the transverse piezoelectric-coupling coefficient d
31,i , and the modulus of elasticity all collectively contribute to the EAPap deflection electrophysics. It also appears that higher sensitivity, with a minimal bias dependence, could be achieved by deliberately adding ions during EAPap processing. [ABSTRACT FROM AUTHOR]- Published
- 2008
- Full Text
- View/download PDF
35. New equivalent circuit model for electrographic discharge to dielectric paper.
- Author
-
Landheer, D.
- Published
- 1980
- Full Text
- View/download PDF
36. Photoacoustic study of layer thickness and moisture content from varnished packaging materials.
- Author
-
Walther, H. G. and Christ, A.
- Subjects
PAPER coatings ,PAPER containers ,PACKAGING equipment ,MATERIALS analysis - Abstract
By means of a photoacoustic gas-cell technique we estimated the thickness of varnish layers on base paper. Interpretation of the measurements was supported by a theoretical model which describes the packaging material as a multilayer stack with freely eligible thermal and optical properties. The variable moisture content could be taken into account using mixture formulas for the definition of thermal effusivity and thermal diffusivity at different percentages of water. Satisfying correspondence between photoacoustic phase slope measurements and calculations simulating water migration was able to be achieved. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]
- Published
- 2001
- Full Text
- View/download PDF
37. Biocellulose-based flexible magnetic paper.
- Author
-
Barud, H. S., Tercjak, A., Gutierrez, J., Viali, W. R., Nunes, E. S., Ribeiro, S. J. L., Jafellici, M., Nalin, M., and Marques, R. F. C.
- Subjects
CELLULOSE ,ELECTROMAGNETIC waves ,X-rays ,IRON oxides ,SPECTRUM analysis ,ADSORPTION (Chemistry) ,MAGNETIC materials - Abstract
Biocellulose or bacterial cellulose (BC) is a biocompatible (nano) material produced with a threedimensional network structure composed of microfibrils having nanometric diameters obtained by the Gluconacetobacter xylinus bacteria. BC membranes present relatively high porosity, allowing the incorporation or synthesis in situ of inorganic nanoparticles for multifunctional applications and have been used as flexible membranes for incorporation of magnetic nanocomposite. In this work, highly stable superparamagnetic iron oxide nanoparticles (SPION), functionalized with polyethylene glycol (PEG), with an average diameter of 5 nm and a saturation magnetization of 41 emu/g at 300K were prepared. PEG-Fe
2 O3 hybrid was dispersed by mixing a pristine BC membrane in a stable aqueous dispersion of PEG-SPION. The PEG chains at PEG-SPION's surface provide a good permeability and strong affinity between the BC chains and SPION through hydrogen-bonding interactions. PEG-SPION also allow the incorporation of higher content of nanoparticles without compromising the mechanical properties of the nanocomposite. Structural and magnetic properties of the composite have been characterized by XRD, SEM, energy-dispersive X-ray spectroscopy (EDX), magnetization, Raman spectroscopy, and magnetic force microscopy. [ABSTRACT FROM AUTHOR]- Published
- 2015
- Full Text
- View/download PDF
38. BubbleID: A deep learning framework for bubble interface dynamics analysis.
- Author
-
Dunlap, C., Li, C., Pandey, H., Le, N., and Hu, H.
- Subjects
INTERFACE dynamics ,BUBBLE dynamics ,DEEP learning ,HEAT flux ,ARCHITECTURAL design ,EBULLITION - Abstract
This paper presents BubbleID, a sophisticated deep learning architecture designed to comprehensively identify both static and dynamic attributes of bubbles within sequences of boiling images. By amalgamating segmentation powered by Mask R-CNN with SORT-based tracking techniques, the framework is capable of analyzing each bubble's location, dimensions, interface shape, and velocity over its lifetime and capturing dynamic events such as bubble departure. BubbleID is trained and tested on boiling images across diverse heater surfaces and operational settings. This paper also offers a comparative analysis of bubble interface dynamics prior to and post-critical heat flux conditions. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
39. Revealing the phase transition scenario in antiferroelectric thin films by x-ray diffuse scattering.
- Author
-
Kniazeva, Maria A., Ganzha, Alexander E., Gao, Ran, Dasgupta, Arvind, Filimonov, Alexey V., and Burkovsky, Roman G.
- Subjects
PHASE transitions ,THIN films ,RADIOGRAPHIC films ,POLARIZATION (Electricity) ,DIELECTRIC measurements ,X-ray scattering - Abstract
There is no consensus among researchers regarding how phase transitions occur in antiferroelectric (AFE) epitaxial heterostructures, in particular, in heterostructures based on model AFE lead zirconate. The questions about the number of phase transitions in such films and by what mechanism they occur remain controversial. This paper presents a look at the phase transition scenario in two types of epitaxial heterostructures: PbZrO 3 /Ba[La–Sn]O 3 /MgO (001) thin films with thicknesses from 25 to 1000 nm and PbZrO 3 /SrRuO 3 /SrTiO 3 (001) thin film 100 nm thick using the diffuse x-ray scattering in the grazing incidence setup. We register the characteristic butterfly-shaped diffuse scattering (DS) intensity distribution in the H K pseudocubic planes, which corresponds to the anisotropic ferroelectric soft mode. No incommensurate soft mode was observed in the cuts of reciprocal space parallel to the film surface by diffuse scattering. We reproduce the shape of DS distribution at different temperatures by the model based on the dielectric stiffness and the electric polarization correlation tensor in the cubic approximation. Such modeling allows not only to characterize the DS parameters from the challengingly low signal-to-background data set, but also to extract experimentally the sensitivity of the materials with respect to inhomogeneous polarization. While the observed temperature evolution of DS is consistent with the dielectric measurements, the correlation between the DS and the phase transition sequence observed by superstructure reflections is yet to be understood better. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
40. Toward new scaling laws for wrinkling in biologically relevant fiber-reinforced bilayers.
- Author
-
Mirandola, A., Cutolo, A., Carotenuto, A. R., Nguyen, N., Pocivavsek, L., Fraldi, M., and Deseri, L.
- Subjects
WRINKLE patterns ,THICK films ,THIN films ,FINITE element method ,PHENOMENOLOGICAL biology - Abstract
Wrinkling, creasing, and folding are frequent phenomena encountered in biological and man-made bilayers made by thin films bonded to thicker and softer substrates often containing fibers. Paradigmatic examples of the latter are the skin, the brain, and arterial walls, for which wiggly cross sections are detected. Although experimental investigations on corrugation of these and analog bilayers would greatly benefit from scaling laws for prompt comparison of the wrinkling features, neither are they available nor have systematic approaches yielding to such laws ever been provided before. This gap is filled in this paper, where a uniaxially compressed bilayer formed by a thin elastic film bonded on a hyperelastic fiber-reinforced substrate is considered. The force balance at the film–substrate interface is here analytically and numerically investigated for highly mismatched film–substrates. The onset of wrinkling is then characterized in terms of both the critical strain and its corresponding wavenumber. Inspired by the asymptotic laws available for neo-Hookean bilayers, the paper then provides a systematic way to achieve novel scaling laws for the wrinkling features for fiber-reinforced highly mismatched hyperelastic bilayers. Such novel scaling laws shed light on the key contributions defining the response of the bilayer, as it is characterized by a fiber-induced complex anisotropy. Results are compared with finite element analyses and also with outcomes of both existing linear models and available ad hoc scalings. Furthermore, the amplitude, the global maximum and minimum of ruga occurring under increasing compression spanning the wrinkling, period doubling, and folding regimes are also obtained. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
41. Plasma propulsion modeling with particle-based algorithms.
- Author
-
Taccogna, F., Cichocki, F., Eremin, D., Fubiani, G., and Garrigues, L.
- Subjects
PLASMA chemistry ,CYCLOTRON resonance ,PLASMA-wall interactions ,PROPELLANTS ,ELECTROMAGNETIC devices ,PLASMA interactions ,ELECTRIC arc - Abstract
This Perspective paper deals with an overview of particle-in-cell/Monte Carlo collision models applied to different plasma-propulsion configurations and scenarios, from electrostatic (E × B and pulsed arc) devices to electromagnetic (RF inductive, helicon, electron cyclotron resonance) thrusters, as well as plasma plumes and their interaction with the satellite. The most important items related to the modeling of plasma–wall interaction are also presented. Finally, the paper reports new progress in the particle-in-cell computational methodology, in particular, regarding accelerating computational techniques for multi-dimensional simulations and plasma chemistry Monte Carlo modules for molecular and alternative propellants. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
42. Layer-by-layer acoustic travel time approximation using ray theory for total focusing method imaging in carbon fiber reinforced polymer.
- Author
-
Cao, Ziyi, Shi, Fangfang, and Zhang, Bixing
- Subjects
CARBON fibers ,MONOMOLECULAR films ,FINITE element method ,TIME management ,POLYMERS - Abstract
This paper proposes a layer-by-layer acoustic travel time approximation method based on ray theory for total focusing method (TFM) imaging in carbon fiber reinforced polymer (CFRP) laminates. The method considers the anisotropy in every monolayer and heterogeneity of CFRP, which approximates the path of propagation as straight in the whole material. The application of this method to TFM imaging is called TravelTimeAppro-TFM. In comparison to isotropic-TFM and Dijkstra-TFM, the experimental results indicated that TravelTimeAppro-TFM outperforms isotropic-TFM in terms of imaging amplitude gain with a maximum gain of 4.67 dB. On the other hand, this approach reduces the computational work compared to Dijkstra-TFM. The proposed method demonstrates significant improvements in both focusing performance and the speed of calculation. This paper also investigates the effective angular range of the layer-by-layer acoustic travel time approximation method through experimental and finite element simulation analysis. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
43. Analysis of near field mutual coupling in wideband magnetoelectric antennas array.
- Author
-
Dong, Biao, Yan, Zhongming, Zhang, Yong, Han, Tianhao, Zhou, Hongcheng, and Wang, Yu
- Subjects
ANTENNA arrays ,MAGNETIC field effects ,ANTENNAS (Electronics) ,SOUND waves ,RESONANCE effect - Abstract
The operating bandwidth of miniaturized magnetoelectric (ME) antenna is generally narrow due to the acoustic wave driven magneto-electromechanical resonance effect, parallel connection of multiple ME antennas with different resonant frequencies is an effective way to broaden the operating bandwidth of the antenna. This paper presents an ME antenna array consisting of three units, which are constructed of a sandwich stack of Metglas/Pb(Mg
1/3 Nb2/3 )O3 –PbTiO3 /Metglas. The −3 dB operating bandwidth of 152.4–172.8 kHz is achieved, and the relative bandwidth is 12.5%. Experimental results indicated that the bias magnetic field and coupling effect between the ME antenna units significantly influence the performance of ME antenna array. A modified Butterworth–Van Dyke (MBVD) equivalent circuit model is used and improved to analyze the influence of sound waves, electric fields, magnetic fields, parasitic capacitance, and bias magnetic field on the ME antenna array. The simulation results of the MBVD equivalent circuit model are agreed well with the experimental results. The improved MBVD model is beneficial for the design of acoustic wave driven antenna array. [ABSTRACT FROM AUTHOR]- Published
- 2023
- Full Text
- View/download PDF
44. High-precision wave height detection of triboelectric nanogenerator by using voltage waveforms and artificial neural network.
- Author
-
Lai, Yuming, Ma, Jiahua, Wen, Honggui, Yao, Huilu, Wei, Wenjuan, Wan, Lingyu, and Yang, Xiaodong
- Subjects
TRIBOELECTRICITY ,WATER waves ,VOLTAGE - Abstract
As we known waves contain important information, however, to realizing high-precision quantification for ocean exploitation and utilization is challenging. In this paper, we proposed a neural network for wave height detection by training the voltage waveform of a triboelectric nanogenerator (TENG). First, we analyzed the voltage signal obtained using a TENG. Second, we proposed a lightweight artificial neural network model that achieves a minimal monitoring error of 0.049% at low amplitudes and yields better monitoring results than the linear model. The findings presented in this paper enable the measurement of water surface waves and eliminate the influence of external factors on sensor performance. Wave parameters can be obtained using neural networks, and this work provides a new strategy for computational and intelligent applications by using wave data. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
45. Second harmonic generation in centrosymmetric multilayered structures: Theoretical approach for nonlinear boundary conditions.
- Author
-
Obeid, B., Ionica, I., Vitrant, G., Damianos, D., and Bastard, L.
- Subjects
SECOND harmonic generation ,NONLINEAR optics ,OPTOELECTRONIC devices - Abstract
Second harmonic generation (SHG) is used to characterize the interfaces of centrosymmetric materials typically used in microelectronic/optoelectronic devices. For such applications, the materials are actually multi-layer stacks, and in this case, the SHG can be difficult to interpret and model. This paper presents the theory of the second harmonic light generated from multilayer structures. The focus is on describing the nonlinear boundary conditions at the interfaces between two different materials, taking into account the distinct contributions of bulk and interface regions. Using these conditions, it is possible to calculate the second harmonic signal from any stack of materials. In this paper, we address stacks containing silicon (100) because it is a material with numerous applications. The nonlinear polarization expressions of the surface and bulk of Si(100), according to Sipe et al. [Phys. Rev. B 35, 1129 (1987)], were integrated into nonlinear boundary conditions in order to determine transmitted and reflected second harmonic waves. An analytical validation was performed on the simple case of an air–silicon interface. For multilayered stacks, the model was compared with experimental results obtained on samples corresponding to pragmatic substrates widely used in microelectronic and optoelectronic applications. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
46. On the polytropic coefficient of negative ions for modeling the sheath and presheath of electronegative plasmas.
- Author
-
Schiesko, L., Lishev, St., Revel, A., Carbone, E., and Minea, T.
- Subjects
ANIONS ,LOW temperature plasmas ,PLASMA chemistry ,CATIONS ,PLASMA sheaths - Abstract
The fluid description is widely used for the multi-dimensional modeling of low temperature plasmas with complex chemistries due to their relative low computational cost. It relies, however, on a series of simplifying assumptions and some truncation of the moment equations for describing the non-equilibrium between the electrons, positive ions, negative ions, and the neutrals. In this paper, the classical assumption of isothermal negative ions is revisited for electronegative plasmas and, more particularly, for the fluid modeling of the transition between the plasma and its sheath. To do so, and in contrast to previous studies, the energy balance equation for the negative ions is also computed, and it allows us to derive the polytropic coefficient γ of the negative ions in addition to one of the positive ions. Strong variations in the sheath and presheath of the negative ions temperature and their polytropic coefficient are observed. The polytropic coefficient is shown to be a strongly varying function of space having for consequence that the negative ions are isothermal only in a very narrow extension of the presheath. For the case considered in this paper, both positive and negative ion flows are nearly adiabatic at the sheath-edge and become adiabatic inside the sheath. This paper shows that classical fluid modeling assumptions need to be verified for each system under consideration, most particularly while modeling the transition from plasma to a wall. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
47. Charged particle-display.
- Author
-
Cho, Sung Nae
- Subjects
INFORMATION display systems ,ELECTRODES ,ELECTRONIC paper ,MATHEMATICAL models ,GOLD ,NANOPARTICLES ,MAXWELL-Boltzmann distribution law - Abstract
An optical shutter based on charged particles is presented. The output light intensity of the proposed device has an intrinsic dependence on the interparticle spacing between charged particles, which can be controlled by varying voltages applied to the control electrodes. The interparticle spacing between charged particles can be varied continuously and this opens up the possibility of particle based displays with continuous grayscale. [ABSTRACT FROM AUTHOR]
- Published
- 2009
- Full Text
- View/download PDF
48. Model for electrostatic imaging of forensic evidence via discharge through Mylar-paper path.
- Author
-
Seward, George H.
- Subjects
ELECTROSTATICS ,PHYSICS - Abstract
Presents a model for the electrostatic detection apparatus. Why the model was developed; Information on the experimental evidence provided to support the model; Role of Mylar-paper in the detection apparatus; Detailed information on the model presented.
- Published
- 1998
- Full Text
- View/download PDF
49. Determination of thin-film stresses on round substrates.
- Author
-
Blech, Ilan A., Blech, Iditt, and Finot, Marc
- Subjects
THIN films ,STRESS concentration ,STRAINS & stresses (Mechanics) ,ELASTIC solids ,CHROMOGENIC compounds ,INDICATORS & test-papers - Abstract
Thin films deposited on wafers show, in some cases, large variations in stress. The local curvature is often used in the Stoney equation [G. G. Stoney, Proc. R. Soc. London, Ser. A 82, 172 (1909)] to calculate the local stress. This practice leads to false stress results. A general method for the calculation of the film stress, for films with isotropic stress, is presented here. The stress is calculated from both the local and overall shape of the substrate. Simple examples of isotropic stress were simulated and the substrate deformation calculated. The film stress was calculated back from the substrate shape with good agreement with the initial stress distribution. The substrate shape under films with centrosymmetric stress distribution can be analytically calculated. The current method successfully calculates the stress distribution from the substrate shape. Some guidelines for the deviation of the calculated stress from that of Stoney’s are given. Finally, the case of nonisotropic stressed film cannot be generally solved since there is no unique stress distribution for any given substrate shape. [ABSTRACT FROM AUTHOR]
- Published
- 2005
- Full Text
- View/download PDF
50. Synthesis, characterizations, and field emission studies of crystalline Na2V6O16 nanobelt paper.
- Author
-
Lim, S. H., Lin, J. Y., Zhu, Y. W., Sow, C. H., and Ji, W.
- Subjects
SEMICONDUCTORS ,CRYSTALS ,ELECTRIC conductivity ,ELECTRICAL engineering materials ,FIELD emission ,ELECTRON emission - Abstract
Crystalline Na
2 V6 O16 ·3H2 O nanobelts have been synthesized by refluxing V2 O5 and NaF and self-weaved into a sheet of paper via a vacuum filtration process. Scanning electron microscopy, x-ray diffraction, and x-ray photoelectron spectroscopy were used to characterize the morphology, structure, and chemical composition of the nanobelt papers. The dehydrated Na2 V6 O16 nanobelts are excellent field emission candidates, with a low turn-on field of 6.8 V/μm, a large current density up to 2.5 mA/cm2 at an electric field of 10 V/μm, and a very uniform distribution of emission sites. [ABSTRACT FROM AUTHOR]- Published
- 2006
- Full Text
- View/download PDF
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.