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Auswahl der wissenschaftlichen Literatur zum Thema „Artificial nanochannels“
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Zeitschriftenartikel zum Thema "Artificial nanochannels"
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Zhao, Yuanyuan, Jin Wang, Xiang-Yu Kong, Weiwen Xin, Teng Zhou, Yongchao Qian, Linsen Yang, Jinhui Pang, Lei Jiang und Liping Wen. „Robust sulfonated poly (ether ether ketone) nanochannels for high-performance osmotic energy conversion“. National Science Review 7, Nr. 8 (02.04.2020): 1349–59. http://dx.doi.org/10.1093/nsr/nwaa057.
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Abstract The membrane-based reverse electrodialysis (RED) technique has a fundamental role in harvesting clean and sustainable osmotic energy existing in the salinity gradient. However, the current designs of membranes cannot cope with the high output power density and robustness. Here, we construct a sulfonated poly (ether ether ketone) (SPEEK) nanochannel membrane with numerous nanochannels for a membrane-based osmotic power generator. The parallel nanochannels with high space charges show excellent cation-selectivity, which could further be improved by adjusting the length and charge density of nanochannels. Based on numerical simulation, the system with space charge shows better conductivity and selectivity than those of a surface-charged nanochannel. The output power density of our proposed membrane-based device reaches up to 5.8 W/m2 by mixing artificial seawater and river water. Additionally, the SPEEK membranes exhibit good mechanical properties, endowing the possibility of creating a high-endurance scale-up membrane-based generator system. We believe that this work provides useful insights into material design and fluid transport for the power generator in osmotic energy conversion.
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Liu, Jie, Tao Zhang und Shuyu Sun. „Molecular Dynamics Simulations of Ion Transport through Protein Nanochannels in Peritoneal Dialysis“. International Journal of Molecular Sciences 24, Nr. 12 (13.06.2023): 10074. http://dx.doi.org/10.3390/ijms241210074.
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In recent decades, the development of dialysis techniques has greatly improved the survival rate of renal failure patients, and peritoneal dialysis is gradually showing dominance over hemodialysis. This method relies on the abundant membrane proteins in the peritoneum, avoiding the use of artificial semipermeable membranes, and the ion fluid transport is partly controlled by the protein nanochannels. Hence, this study investigated ion transport in these nanochannels by using molecular dynamics (MD) simulations and an MD Monte Carlo (MDMC) algorithm for a generalized protein nanochannel model and a saline fluid environment. The spatial distribution of ions was determined via MD simulations, and it agreed with that modeled via the MDMC method; the effects of simulation duration and external electronic fields were also explored to validate the MDMC algorithm. The specific atomic sequence within a nanochannel was visualized, which was the rare transport state during the ion transport process. The residence time was assessed through both methods to represent the involved dynamic process, and its values showed the temporal sequential order of different components in the nanochannel as follows: H2O > Na+ > Cl−. The accurate prediction using the MDMC method of the spatial and temporal properties proves its suitability to handle ion transport problems in protein nanochannels.
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Kaya, Dila, Vanina M. Cayón, Christina Trautmann und Maria Eugenia Toimil Molares. „Biosensing with Tailored Track-Etched Nanochannels“. ECS Meeting Abstracts MA2023-02, Nr. 57 (22.12.2023): 2785. http://dx.doi.org/10.1149/ma2023-02572785mtgabs.
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Inspired by the high sensitivity, efficiency and selectivity of biological ion channels, the development of solid-state nanochannel sensors has been at the forefront of nanotechnology research in the last years. Many researchers worldwide have concentrated their efforts on the development of artificial nanochannels that can mimic the features of biological ion channels. These synthetic nanostructures are based on abiotic materials which provide higher robustness, thermal stability, chemical versatility and mechanical resistance than their biological counterparts. Furthermore, synthetic nanochannels and specific surface functionalization strategies have enabled fine control over the geometry and charge distribution which yielded the ability to manipulate the flux of ions through the channel. This gave rise to the formation of nanochannel-based platforms with applications in (bio)sensing as well as other fields. The development of chemical- and biosensors requires a combination of reliable nanofabrication techniques and versatile surface modification strategies, which render high sensitivity and high selectivity, respectively [1]. Tailored single polymer nanochannels are routinely fabricated by ion-track nanotechnology. Polymer films are first irradiated with individual swift heavy ions at the GSI UNILAC accelerator. Each ion generates a highly localized cylindrical damage zone along its trajectory. These so-called ion tracks are subsequently dissolved and enlarged in a chemical etching process. By selecting suitable etching conditions, geometry (cylindrical, conical or bullet-like) and size of the nanochannels can be adjusted. The nanochannel surface can then be functionalized by means of different chemical strategies to enhance the sensing capabilities. There are two main nanochannel sensing techniques, ion current rectification (ICR) and resistive-pulse sensing (RPS). Both are affected by the geometry and surface charge of the nanochannel and based on measuring the change in ion current flowing through the channel induced by the chosen analyte [2]. In both approaches, the presence of a target analyte triggers a variation in the physicochemical properties of the channel which can be related to measurable changes in the transmembrane current, and is proportional to the analyte concentration. In this contribution, we will present nanochannel sensing platforms based on several single polymer channels fabricated by ion-track nanotechnology and a selection of surface functionalization strategies applied to the nanochannels. We will then discuss selected examples recently obtained with these tailored functionalized nanochannels and demonstrate selective and sensitive sensing applications based on both the ICR and RPS phenomena. [1] Toum Terrones, Y., Cayón, V. M., Laucirica, G., Cortez, M. L., Toimil-Molares, M. E., Trautmann, C., ... & Azzaroni, O. (2022). Ion Track-Based Nanofluidic Biosensors. In Miniaturized Biosensing Devices: Fabrication and Applications (pp. 57-81). Singapore: Springer Nature Singapore. [2] Kaya, D., & Keçeci, K. (2020). Track-etched nanoporous polymer membranes as sensors: A review. Journal of The Electrochemical Society, 167(3), 037543.
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Shen, Yigang, Xin Wang, Jinmei Lei, Shuli Wang, Yaqi Hou und Xu Hou. „Catalytic confinement effects in nanochannels: from biological synthesis to chemical engineering“. Nanoscale Advances 4, Nr. 6 (2022): 1517–26. http://dx.doi.org/10.1039/d2na00021k.
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The minireview summarizes the latest progress on catalytic confinement effects associated with biological synthesis in bio-nanochannels and catalytic reactions in artificial nanochannels in chemical engineering.
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Yang, Lingling, Kuanzhi Qu, Junli Guo, Huijie Xu, Zhenqing Dai, Zhi-Da Gao und Yan-Yan Song. „Asymmetric coupling of Au nanospheres on TiO2 nanochannel membranes for NIR-gated artificial ionic nanochannels“. Chemical Communications 55, Nr. 97 (2019): 14625–28. http://dx.doi.org/10.1039/c9cc08317k.
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Au nanospheres are selectively formed at one tip of TiO2 nanochannels by combining a photocatalytic reaction with limited penetration of light. The closed–open switching behavior of the temperature-responsive polymer is achieved under NIR irradiation.
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Han, Cuiping, Xu Hou, Huacheng Zhang, Wei Guo, Haibing Li und Lei Jiang. „Enantioselective Recognition in Biomimetic Single Artificial Nanochannels“. Journal of the American Chemical Society 133, Nr. 20 (25.05.2011): 7644–47. http://dx.doi.org/10.1021/ja2004939.
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Sutisna, B., G. Polymeropoulos, E. Mygiakis, V. Musteata, K. V. Peinemann, D. M. Smilgies, N. Hadjichristidis und S. P. Nunes. „Artificial membranes with selective nanochannels for protein transport“. Polymer Chemistry 7, Nr. 40 (2016): 6189–201. http://dx.doi.org/10.1039/c6py01401a.
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Membranes based on poly(styrene-b-4-hydroxystyrene-b-styrene) were prepared with nanochannels for preferential transport of proteins with molecular weight 14.3 kg mol−1 and rejection of neutral polyethylene glycol molecules with molecular size of 10 kg mol−1.
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Zhang, Qianqian, Zhaoyue Liu und Jin Zhai. „Photocurrent generation in a light-harvesting system with multifunctional artificial nanochannels“. Chemical Communications 51, Nr. 61 (2015): 12286–89. http://dx.doi.org/10.1039/c5cc04271b.
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Liu, Shanshan, Rongjie Yang, Xingyu Lin und Bin Su. „Gated thermoelectric sensation by nanochannels grafted with thermally responsive polymers“. Chemical Communications 56, Nr. 91 (2020): 14291–94. http://dx.doi.org/10.1039/d0cc06734b.
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Hsu, Jyh-Ping, Yu-Min Chen, Chih-Yuan Lin und Shiojenn Tseng. „Electrokinetic ion transport in an asymmetric double-gated nanochannel with a pH-tunable zwitterionic surface“. Physical Chemistry Chemical Physics 21, Nr. 15 (2019): 7773–80. http://dx.doi.org/10.1039/c9cp00266a.
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Bioinspired, artificial functional nanochannels for intelligent molecular and ionic transport control have versatile potential applications in nanofluidics, energy conversion, and controlled drug release.
Dissertationen zum Thema "Artificial nanochannels"
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Du, Haiqin. „Beta-Cyclodextrin-based artificial nanochannel scaffolds inserted in polymeric membrane“. Electronic Thesis or Diss., Sorbonne université, 2021. http://www.theses.fr/2021SORUS262.
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Ce projet de thèse visait à construire une plateforme polyvalente en nanotechnologie, conçue comme un compartiment de type polymère, équipé de nanocanaux artificiels à base de bêta-cyclodextrine (βCD). Des polymersomes bien définis ont été produits via l'auto-assemblage de copolymères à blocs amphiphiles linéaires, polyglycidol-b-poly(oxyde de butylène)-b-polyglycidol (PGL-PBO-PGL), possédant une stabilité à long terme et une capacité antisalissure. Des copolymères amphiphiles en étoile, à cœur βCD, bien définis, βCD-(PBO-PGL)14, ont également été synthétisés avec une longueur sur mesure de chaque bloc, une faible dispersité et une pureté élevée. Les comportements d'auto-assemblage des copolymères étoiles amphiphiles étaient similaires à ceux de leurs homologues linéaires. En outre, la perméabilité de la membrane polymère, constituée de copolymères linéaires ou en étoile, aux ions (H+, K+, Cl-) a été étudiée par spectroscopie de fluorescence et par mesures de type BLM : il a été montré des comportements différents pour les copolymères linéaires et en étoile. Il semble que les copolymères étoiles βCD-(PBO-PGL)14 pourraient s'insérer dans la membrane plane PGL-PBO-PGL, mais des investigations supplémentaires doivent être effectuéesThis PhD project aimed to construct a versatile platform for nanotechnological applications, which was designed as a polyglycidol (PGL)-based polymersomal compartment equipped with beta-cyclodextrin (¦ÂCD)-based artificial nanochannels. Well-defined polymersomes have been produced via self-assembling of linear amphiphilic block copolymers, polyglycidol-block-poly(butylene oxide)-block-polyglycidol (PGL-PBO-PGL), possessing long-term storage stability and antifouling capacity. Well-defined ¦ÂCD-cored star amphiphilic copolymers, ¦ÂCD-(PBO-PGL)14, have also been synthesized with tailor-made length of each block, low polydispersity and high purity. The self-assembly behaviors of the amphiphilic star copolymers were similar to those of their linear counterparts. Additionally, the permeability of the polymeric membrane made of linear or star copolymers to small ions (H+, K+, Cl-) were investigated by fluorescence spectroscopy and BLM-type measurements: different behaviors for linear and star copolymers have been shown. It seems that βCD-(PBO-PGL)14 star copolymers could insert into the planar PGL-PBO-PGL membrane, but further investigations have to be performed
Konferenzberichte zum Thema "Artificial nanochannels"
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Duan, Chuanhua, Rohit Karnik, Ming-Chang Lu und Arun Majumdar. „Evaporation Induced Cavitation in Nanochannels“. In 2010 14th International Heat Transfer Conference. ASMEDC, 2010. http://dx.doi.org/10.1115/ihtc14-23272.
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Cavitation refers to a nucleation phenomenon that occurs at room temperature when the liquid pressure is below the corresponding saturation vapor pressure. Although water confined by a nanochannel and a liquid-air meniscus is under negative pressure, i.e. much smaller than the corresponding satraton vapor pressure, cavitation has not been observed in any nanochannels. In this work, we report our observation and studies of cavitations in nanochannels for the first time. 1-D confined nanochannels for this work were fabricated based on a sacrificial-layer-etching scheme. The unique cavitation phenomenon occurred when water started evaporation at the nanochannel entrances. Instead of meniscus recession, a bubble was present inside the nanochannel and two meniscii were pinned at the entrances. This bubble started growing along both directions until it totally occupied the whole channel. We found that the bubble grows linearly with time and the bubble growth rate decreases with the increasing channel height. A theoretical model was developed to study this dynamic process. It is found that the bubble growth rate is determined by the evaporation rate at the entrance. Since the total evaporation flux is a constant, the predicted bubble growth rate is reversely proportional to the channel height, quantitatively consistent with the experimental results. Since most current studies for caviation are theoretical studies, our studies provide a new experimental approach to study these phenomena in artificial transparent nanochannel devices.
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Xu, Dongyan, Deyu Li, Yongsheng Leng und Yunfei Chen. „Molecular Dynamics Simulation of Ion Distribution in Nanochannels“. In ASME 2006 International Mechanical Engineering Congress and Exposition. ASMEDC, 2006. http://dx.doi.org/10.1115/imece2006-15075.
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Ion distribution in nanochannels with overlapped electric double layers is important for understanding many interesting phenomena in nature and designing novel nanofluidic devices for different applications. Molecular Dynamics has been proved to be a powerful tool to study the ion distribution and electroosmotic flow inside nanochannels. However, a big problem in molecular dynamics simulation is the assignment of the number of ions in the simulation domain since no theory is available to determine the number of ions in the nanochannel, which is directly related to the chemical potential of the bulk electrolyte. In the literature, attention has been paid mainly to meet the requirement of the overall neutrality among surface charges and mobile ions. However, since both positive and negative ions may exist in the solution, the exact number of positive and negative ions corresponding to certain bulk concentration was unknown and assigned somewhat arbitrarily. We believe that this arbitrary assignment may lead to artificial results and tries to attack this fundamental problem in molecular dynamics simulation by extending the simulation domain to include two bulk regions sandwiching the nanochannel of interest. This way, when the system reaches equilibrium, the concentration of the electrolyte in the bulk region and the number of ions in the center region will emerge naturally instead of artificially assigned. It was shown that both cation and anion concentrations in the nanochannel could be significantly different from the ion concentration in the bulk region.
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Boone, C., M. Fuest, K. Wellmerling und S. Prakash. „Effect of Time Dependent Excitation Signals on Gating in Nanofluidic Channels“. In ASME 2015 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/imece2015-53038.
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Nanofluidic field effect devices feature a gate electrode embedded in the nanochannel wall. The gate electrode creates local variation in the electric field allowing active, tunable control of ionic transport. Tunable control over ionic transport through nanofluidic networks is essential for applications including artificial ion channels, ion pumps, ion separation, and biosensing. Using DC excitation at the gate, experiments have demonstrated multiple current states in the nanochannel, including the ability to switch off the measured current; however, experimental evaluation of transient signals at the gate electrode has not been explored. Modeling results have shown ion transport at the nanoscale has known time scales for diffusion, electromigration, and convection. This supports the evidence detailed here that use of a time-dependent signal to create local perturbation in the electric field can be used for systematic manipulation of ionic transport in nanochannels. In this report, sinusoidal waveforms of various frequencies were compared against DC excitation on the gate electrode. The ionic transport was quantified by measuring the current through the nanochannels as a function of applied axial and gate potentials. It was found that time varying signals have a higher degree of modulation than a VRMS matched DC signal.
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Caldag, Hakan Osman, und Serhat Yesilyurt. „Dynamics of Artificial Helical Microswimmers Under Confinement“. In ASME 2018 16th International Conference on Nanochannels, Microchannels, and Minichannels. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/icnmm2018-7632.
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Understanding trajectories of natural and artificial helical swimmers under confinement is important in biology and for controlled swimming in potential medical applications. Swimmers follow helical or straight trajectories depending on whether the helical tail is pushing or pulling the swimmer. To investigate swimming dynamics of helical swimmers further, we present a Computational Fluid Dynamics (CFD) model for simulation of an artificial microswimmer in cylindrical channels. The microswimmer has a cylindrical head and a left-handed helical tail. The kinematic model solves for the position and rotation of the swimmer based on the linear and angular velocities of the force-free swimmer from a CFD model. Third-order Adams-Bashforth solver is used to obtain the orientation and the position of the swimmer. Viscous, gravitational, magnetic and contact forces and torques are considered in the model. The model is validated with experimental results. 3D trajectories, propulsion and tangential velocities are reported.
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Kuzma-Kichta, Yu A., A. Lavrikov, S. Afonin und M. Shustov. „Boiling Investigation on a Surface With Artificial and Natural Nucleons Sites“. In ASME 2008 6th International Conference on Nanochannels, Microchannels, and Minichannels. ASMEDC, 2008. http://dx.doi.org/10.1115/icnmm2008-62212.
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The water and Na2SO4 water solution boiling investigation had been carried in pool on the surfaces with artificial and natural nucleons sites under different pressures using high speed digital camera. The boiling of water was investigated at atmosphere pressure on a surface with a artificial nucleons site, which had a micro scale (cavity’s diameters – 100 and 200 μm and depth – 80 μm), in the Fridrich-Alexander University Erlangen-Nu¨rnberg, Germany in the Institute of Fluid Mechanics. The boiling of water and Na2SO4 water solution with concentration 20 g/l was investigated on a surface with natural nucleons sites in the pressure range 0.1 – 1 MPa in the Moscow Power-Engineering Institute (Technical University) on department of Thermal Physics. The “hand” video processing was used for the study’s results in case of the pool boiling on a surface with a artificial nucleon site. The data processing was realized for the study’s results using with a program “Bubble Detector”, which was specially developed for case of the pool boiling on a surface with the natural nucleon sites, and the “hand” processing was carried for video, which showed the reliability of the program “Bubble Detector”. First the distributions and dependences of basic boiling characteristics (frequency, departure diameter) were obtained at water pool boiling on a surface with a artificial cavity in the range of heat flux from 20 to 128 kW/m2 and the time dependence of vapor bubble’s grow. It was obtained, that departure diameters of vapor bubbles do not depend in case of boiling on a surface with a single cavity practically on heat flux. First the distributions and dependences of swimming velocities and equivalent diameters were obtained at water and Na2SO4 water solution with concentration 20 g/l pool boiling on a surface with natural nucleon sites in range of pressures from 0.1 to 1 MPa. The comparison of diameters’ and swimming velocities’ distributions of vapor bubbles was carried for under consideration conditions.
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Suciu, Claudiu Valentin. „Energy Dissipation During Liquid Adsorption/Desorption In/From Liquid-Repellent Nanochannels“. In ASME 2008 6th International Conference on Nanochannels, Microchannels, and Minichannels. ASMEDC, 2008. http://dx.doi.org/10.1115/icnmm2008-62040.
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Ability of viscous fluids, flowing in narrow interstices, to dissipate the mechanical energy of shock and vibration is well known. In recent years, connected to the nano-technological development, solid-liquid interfaces have been used to dissipate surface energies, in systems where the solid is liquid-repellent; such interfaces are able to store, release or transform the energy. Thus, the contact angle hysteresis can be applied to dissipate the mechanical energy, and this kind of energy loss, in which not the viscosity but the surface tension of the liquid plays the main role, is called surface dissipation. In fact a liquid nano-porosimeter that exhibits nano-damping ability, when applied to mechanical systems is called colloidal damper. Concretely, during the cyclical adsorption/desorption of the liquid (e.g., water or aqueous solutions) in/from the liquid-repellent nanochannels (e.g., modified nanoporous silica gel) the energy is dissipated. Such absorber is convenient from the ecological standpoint since it is oil-free and since both the silica gel (artificial sand with controlled architecture) and the liquid are environment-friendly. Connected to this attractive kind of energy loss, one of the problems awaiting solution is that a theoretical model of the surface dissipation remains to be developed and validated by tests. Accordingly, in this work, based on a detailed discussion of the mechanism of surface dissipation one reveals that the parameters which determine the magnitude of the energy loss are the silica gel mass, the liquid and solid surface tensions, and an integral function (specific pore surface) which is related to the nano-architecture of the liquid-repellent coating, to the silica gel pore architecture and to the maximum applied pressure. Silica gel particles are supposed to be obtained through the aggregation of nano-particles, producing rough nanochannels of variable radius, and normal distribution fits quite well the measured pores size distributions. Heterogeneous molecules of the liquid-repellent coating have a methyl group as head, and a body consisted of methylene groups; they produce a nanopillar structure on the silica gel surface. Maximization of the surface dissipation for imposed working liquid or imposed coating molecule is discussed. Test rig is a compression-decompression chamber used to validate the theoretical findings. Results obtained are useful in general for the appropriate design of liquid-repellent nanochannels with technological applications, and in particular for the absorber optimum design under imposed requirements.
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Kim, Seontae, Hyungmo Kim, Hyung Dae Kim, Ho Seon Ahn, Moo Hwan Kim, Joonwon Kim und Goon-Cherl Park. „Experimental Investigation of Critical Heat Flux Enhancement by Micro/Nanoscale Surface Modification in Pool Boiling“. In ASME 2008 6th International Conference on Nanochannels, Microchannels, and Minichannels. ASMEDC, 2008. http://dx.doi.org/10.1115/icnmm2008-62289.
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Nanofluids, which contain uniformly and stably dispersed nanoparticles, exhibit an abnormal enhancement of the critical heat flux (CHF) when used as a working fluid in pool boiling. It has recently been demonstrated that optimal CHF enhancement in nanofluids is attained by the significant deposition of nanoparticles on the heater surface during pool boiling. The surface deposition of oxidized metal nanoparticles significantly enhances the wettability, and fractal micro/nanostructures formed by nanoparticle deposition induce liquid suction due to capillary wicking. It is supposed that the superior wettability and capillary wicking of the nanoparticle-fouled surface enhances CHF by promoting the dry patches to be effectively rewetted during the boiling process. In this regard, the excellent CHF performance of the nanoparticle-deposited surface can be reproduced using artificial structures via innovative surface-modification methods that yield good wettability and capillarity. To accomplish this goal, we plan to design and fabricate various artificial micro/nano-structured surfaces with good surface wettability and capillarity, and investigate their CHF performance. In the present study, we examined experimentally the CHF performances of a series of surface-modified samples (plane, micro-structured, nano-structured, and micro/nano structured surfaces). Pool boiling heat transfer of pure water on sample surfaces was investigated under atmospheric conditions. The CHF increase due to artificial surface modification is discussed based on solid-liquid interfacial parameters (static contact angle, roughness) that are closely related to CHF phenomenon in pool boiling.
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Nedea, S. V., A. J. Markvoort, P. Spijker und A. A. van Steenhoven. „Heat Transfer Predictions Using Accommodation Coefficients for a Dense Gas in a Micro/Nano-Channel“. In ASME 2008 6th International Conference on Nanochannels, Microchannels, and Minichannels. ASMEDC, 2008. http://dx.doi.org/10.1115/icnmm2008-62179.
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The influence of gas-gas and gas-wall interactions on the heat flux predictions for a dense gas confined between two parallel walls of a micro/nano-channel is realized using combined Monte Carlo (MC) and Molecular Dynamics (MD) techniques. The accommodation coefficients are computed from explicit MD simulations. These MD coefficients are then used as effective accommodation coefficients in Maxwell-like boundary conditions in MC simulations. We find that heat flux predictions from MC based on these coefficients compare good with the results of explicit simulations except the case when there are hydrophobic gas-wall/gas-gas interactions. For this case an artificial wall was introduced in order to measure these MD accommodation coefficients at this artificial border. Good agreement is found then for both hydrophilic and hydrophobic gas-wall interactions and we show this by confronting the heat fluxes from explicit MD simulations with the the MC heat flux predictions for all the generic accommodation coefficients.
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Sato, Takato, Yasuo Koizumi und Hiroyasu Ohtake. „Experimental Study on Behavior of Bubbles and Temperature Fluctuation of Heat Transfer Surface by Using Heat Transfer Surface With Artificial Cavities Created by MEMS Technology“. In ASME 2009 7th International Conference on Nanochannels, Microchannels, and Minichannels. ASMEDC, 2009. http://dx.doi.org/10.1115/icnmm2009-82276.
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Pool nucleate boiling heat transfer experiments were performed for water using heat transfer surfaces having a unified cavity. A single cylindrical hole of 10 μm in diameter and 40 μm in depth was formed on a mirror-finished silicon wafer of 0.2 mm in thickness using the Micro-Electro Mechanical Systems (MEMS) technology. This silicon plate was used as the heat transfer surface. The back side of the heat transfer surface was heated by a semi-conductor laser beam. The back-side surface temperature was measured by a radiation thermograph with a temperature resolution of 0.08 K and a time resolution of 3 ms/line. Experiments were conducted in the range up to 1.35 × 105 W/m2. The standard deviations of the local fluctuating heat transfer surface temperature were calculated. So the cross-correlation coefficients between the cavity center and a certain point were calculated by using the standard deviations and the time-series surface temperature data. Then, the intensity of the thermal influence exerted by the boiling bubbles on the local position was derived. The thermal influence extents determined from the intensity were 2.1 – 3.3 times larger than the mean diameter of all departure bubbles in the present experimental range.
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Rostamy, Noorallah, Soheil Akbari, David Sumner und Donald J. Bergstrom. „Calibration of Triple-Wire Probes Using an Artificial Neural Network“. In ASME 2010 3rd Joint US-European Fluids Engineering Summer Meeting collocated with 8th International Conference on Nanochannels, Microchannels, and Minichannels. ASMEDC, 2010. http://dx.doi.org/10.1115/fedsm-icnmm2010-31198.
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Hot-wire anemometry is an established technique for velocity measurements in turbulent flows. Calibration of hot-wire probes is challenging due to the nonlinear relationship between the probe output voltage and the velocity, and the sensitivity to the temperature difference between the heated wire and the ambient flow. A triple-wire probe contains three mutually orthogonal wires that permit the three components of the local instantaneous velocity vector to be measured simultaneously. Calibration data reduction methods for multi-wire probes, based on variable-angle calibration techniques, may include curve-fits and direct-interpolation schemes. In the present study, a novel calibration data reduction method for a triple-wire probe is reported which uses an artificial neural network. Such a method has been successfully applied by other researchers for the calibration of seven-hole pressure probes. For the triple-wire probe, the neural network is used to produce a calibration relation between the three probe output voltages and the three components of the local velocity vector. Variable-angle calibration data were obtained for a triple-wire probe for velocity magnitudes from 5 to 40 m/s, yaw angles from −35° to +35°, and roll angles from 0° to 345°. A three-layer perceptron feed-forward network, using a Levenberg-Marquardt training algorithm, was applied to the calibration data, to map the mean voltages to the mean velocity components. The network was tested using an independent data set. The present results yielded standard errors of approximately ±0.38 m/s, ±0.25 m/s and ±0.26 m/s in the magnitudes of the streamwise, vertical, and cross-flow velocity components, respectively. The results showed that the present neural network model is not significantly sensitive to the size of the calibration data set, suggesting it may be a more convenient calibration data reduction method compared to other methods.