Artykuły w czasopismach: „Surface generation techniques”

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Nafi, Muhammad Abdun, i Muhammad Pervej Jahan. "Functional Surface Generation by EDM—A Review". Micromachines 14, nr 1 (31.12.2022): 115. http://dx.doi.org/10.3390/mi14010115.

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Electro-discharge machining (EDM) removes electrically conductive materials by high frequency spark discharges between the tool electrode and the workpiece in the presence of a dielectric liquid. Being an electrothermal process and with melting and evaporation being the mechanisms of material removal, EDM suffers from migration of materials between the tool and the workpiece. Although unwanted surface modification was considered a challenge in the past for many applications, this inherent nature of the EDM process has recently become of interest to the scientific community. As a result, researchers have been focusing on using the EDM process for surface modification and coating by targeted surface engineering. In order to engineer a surface or generate functional coatings using the electro-discharge process, proper knowledge of the EDM process and science of electro-discharge surface modification must be understood. This paper aims to provide an overview of the electro-discharge surface modification and coating processes, thus assisting the readers on exploring potential applications of EDM-based techniques of surface engineering and coating generation. This review starts with a brief introduction to the EDM process, the physics behind the EDM process, and the science of the surface modification process in EDM. The paper then discusses the reasons and purposes of surface modification and coating practices. The common EDM-based techniques reported in the literature for producing coatings on the surface are discussed with their process mechanisms, important parameters, and design considerations. The characterization techniques used for the analysis of modified surfaces and coating layers, as well as the tribological and surface properties of modified surfaces or coatings are discussed. Some of the important applications of EDM-based surface modification and coating processes are generating surfaces for protective coating, for aesthetic purposes, for enhancing the biocompatibility of implants, for improving corrosion resistance, for improving wear resistance, and for improving tribological performance. The current state of the research in these application areas is discussed with examples. Finally, suggestions are provided on future research directions and innovative potential new applications of the electro-discharge-based surface engineering and coating processes.

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Ghafurian, Mohammad Mustafa, Hamid Niazmand, Ehsan Ebrahimnia-Bajestan i Robert A. Taylor. "Wood surface treatment techniques for enhanced solar steam generation". Renewable Energy 146 (luty 2020): 2308–15. http://dx.doi.org/10.1016/j.renene.2019.08.036.

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Wong, Kiing S., Nicholas S. L. Chew, Mary Low i Ming K. Tan. "Plasma-Activated Water: Physicochemical Properties, Generation Techniques, and Applications". Processes 11, nr 7 (23.07.2023): 2213. http://dx.doi.org/10.3390/pr11072213.

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Plasma-activated water (PAW) is water that has been treated with atmospheric pressure plasma. Due to the presence of reactive oxygen and nitrogen species (RONS), PAW can be used in various applications such as (1) surface disinfection and food decontamination, (2) enhancement in seed germination, and (3) enhancement in surface cooling in the nucleate boiling regime. Briefly, for surface disinfection, the reactive species in PAW can induce oxidative stress on microbes; for enhancement of seed germination, the reactive species in PAW can trigger seed germination and provide nutrients; for enhancement in surface cooling, the reactive species cause a reduction in the surface tension of PAW, facilitating the phase-change heat transfer and, quite unexpectedly, minimizing the surface oxidation. Here, we review the physicochemical properties of PAW, the three commonly used techniques (plasma jet, dielectric barrier discharge, and corona discharge) for generating atmospheric pressure plasma, and the use of PAW for the above three applications. In particular, we review the recent development of the miniaturization of the plasma generator integrated with an acoustic neutralizer to produce plasma-activated aerosols, elimination of the need for storage, and the interesting physicochemical properties of PAW that lead to cooling enhancement.

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Tong, Gang, Maria Savchenko i Ichiro Hagiwara. "Polygonal Mesh Partitioning for NURBS Surface Generation". Advanced Materials Research 204-210 (luty 2011): 1824–29. http://dx.doi.org/10.4028/www.scientific.net/amr.204-210.1824.

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Surface reconstruction and NURBS surface generation based on 3D surface mesh partitioning are more essential today. In this paper, we present a new method of automatic partitioning complex surface meshes into the bounded regions with four corner points (quadrilateral regions) based on using control points (notches) for NURBS surface generation. The procedure of this method consists of 4 major steps: (1) the 3D polygons mapping into 2D polygons; (2) convex decomposition of the polygons in the 2D space; (3) subdivision of each polygons into quadrilateral regions; (4) mapping the received 2D regions onto the 3D original surface mesh. Main contribution in this paper is automatic partitioning of the 3D segmented parts of complex surfaces into quadrilateral regions based on combination of segmentation, mapping, and subdivision techniques. Automatic partitioning allows us to create not rectangular but quadrilateral regions without using any user-dependent parameters for further NURBS surface generation.

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Chen, Y. J., i B. Ravani. "Offset Surface Generation and Contouring in Computer-Aided Design". Journal of Mechanisms, Transmissions, and Automation in Design 109, nr 1 (1.03.1987): 133–42. http://dx.doi.org/10.1115/1.3258777.

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Two computational techniques are presented for Computer-Aided Design (CAD) and Machining (CAM) of parametrically defined surfaces. One technique deals with construction of offset surfaces. An algorithm is presented that would allow detection and removal of the closed loop on the offset surface due to its self-intersection. The second computational technique presented deals with contouring of parametric surfaces. The technique presented allows for optimal generation of planar contour lines. The results are applied to Numerical Control (NC) machining of surfaces.

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Iancu, Florin, John Trevino i Steven Sommer. "Numerical Analysis of Blade Geometry Generation Techniques for Centrifugal Compressors". International Journal of Rotating Machinery 2007 (2007): 1–7. http://dx.doi.org/10.1155/2007/48683.

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It is a known fact that machined impellers result in improved compressor performance compared to cast impellers of the same design. The performance improvements can be attributed to better surface finish, more accurate geometric definition (tighter dimensional tolerances), well-defined edges, and the lack of blade tip fillet on shrouded impellers. In addition, it has been observed through experimental investigations that the construction method of the impellers has an impact on performance. This paper presents computational fluid dynamic investigations of two types of impellers, with blade surfaces generated using straight-line elements (SLEs) and CAD arbitrary definitions. Because there are many different mathematical definitions that CAD tools employ for curves, the resulting arbitrary blade surface is not unique. The numerical results will help understand the causes of the performance differences as well as the effects of SLE blades on the flow through the impeller. Input conditions for computational dynamic simulations are based on experimental results. All references to experimental data in the present paper are for cast impellers. Therefore, the differences in performance are attributed to blade definition (SLE versus other) and not to differences resulting from manufacturing methods.

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Ma, Wan. "Isothermal hydrodynamic pressure and load carrying capacity of parallel rough surfaces based on FFT techniques". Transactions of the Canadian Society for Mechanical Engineering 44, nr 4 (1.12.2020): 602–12. http://dx.doi.org/10.1139/tcsme-2019-0174.

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In lubricated contacts, the component macrogeometry (radius of curvature) determines the pressure generation, and the surface microgeometry (i.e., roughness) alters it somewhat. However, for parallel surfaces, the microgeometry completely determines the hydrodynamic lubrication. This paper extends earlier work to numerically solve the isothermal hydrodynamic pressure generation and load carrying capacity (LCC) of surfaces with more complicated roughness features. A fast Fourier transform (FFT)-based method is described to quickly obtain the pressure distribution. The method is applicable to both real surface topographies and artificially generated rough surfaces. Results show that it enables one to predict the hydrodynamic pressure, when cavitation is negligible. The relative error of the LCC over the central domain is smaller than 8% and a 500× time saving, compared with the numerical method, is obtained.

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Rasouli, Rahimeh, Ahmed Barhoum i Hasan Uludag. "A review of nanostructured surfaces and materials for dental implants: surface coating, patterning and functionalization for improved performance". Biomaterials Science 6, nr 6 (2018): 1312–38. http://dx.doi.org/10.1039/c8bm00021b.

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CAVANAGH, M., J. R. POWER, J. F. McGILP, H. MÜNDER i M. G. BERGER. "OPTICAL SECOND-HARMONIC GENERATION FROM POROUS SILICON IN UHV". Surface Review and Letters 01, nr 04 (grudzień 1994): 585–88. http://dx.doi.org/10.1142/s0218625x94000722.

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The origin of the luminescence from porous Si (PS) is currently under intense scrutiny. Characterisation of this material on the atomic scale is difficult and optical techniques offer certain advantages. Ultrahigh vacuum studies of PS by optical second-harmonic generation (SHG) are presented. Excitation wavelengths corresponding to surface state and a suspected strain resonance from clean Si surfaces are used. Hydrogen-terminated and clean surfaces of Si(100) and PS are compared. The H-terminated surfaces give no signal under the excitation conditions used. On desorbing the hydrogen, a stable SH signal is obtained from the PS which has polarisation dependences different to those of clean Si(100), and which also differ between the surface and strain resonances.

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Ocaña, José L., Daniel Huerta-Murillo, Andrés Fabián Lasagni, Alfredo Ismael Aguilar-Morales, Sabri Alamri, Jose T. Cardoso, Angel García-Beltrán, Francisco Cordovilla i Ignacio Angulo. "Modification of Ti6Al4V surface properties by combined DLW-DLIP hierarchical micro-nano structuring". Advanced Optical Technologies 9, nr 3 (25.06.2020): 121–30. http://dx.doi.org/10.1515/aot-2019-0071.

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AbstractThe use of pulsed laser irradiation techniques has proven to be a clearly effective procedure for the achievement of surface properties modification via micro-/nano-structuration, different conceptual approaches having been the subject of research and extensively reported in the literature. Completing the broad spectrum of applications developed mostly involving the generation of structured surfaces (particularly of metallic materials) with specific contact, friction and wear functionalities, the application of laser sources to the surface structuration of metal surfaces for the modification of their wetability and corrosion resistance properties is considered. The particular problems found for the generation of the appropriate surface microstructure able to replicate the hydrophobic behaviour of some live structures present in nature, their long term stability and their amenability to macroscopic scale are discussed along with innovative methods to generate the required hierarchical micro-/nano-structures by a combination of the DLW and DLIP techniques.

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Finster, Ken, Robert Small, Andrea Belz, John Mahoney, Julius Perel i Jian Gong. "Applications of Electrostatic Spray Techniques to Surface Cleaning". Solid State Phenomena 145-146 (styczeń 2009): 51–54. http://dx.doi.org/10.4028/www.scientific.net/ssp.145-146.51.

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Conventional cleaning technologies have been effective in removal of particles, metals, and organic films. However, two trends motivating the development of new techniques are 1) the desire to minimize the environmental impact of large volumes of cleaning solutions; and 2) the need to clean at the sub-45 nm level, consistent with decreasing feature sizes. We report here on the initial characterization of a system to apply electrospray techniques to variants of the SC-1 and SC-2 solutions, as well as to solvent mixtures. We describe the generation of submicron sized droplets (<1 m radius) of cleaning mixtures and demonstrate a preliminary methodology, using a combination of experimental data and phenomenological modeling approaches, to characterize the physics of the droplet-surface interaction

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Vasarmidis, Panagiotis, Vasiliki Stratigaki, Tomohiro Suzuki, Marcel Zijlema i Peter Troch. "Internal Wave Generation in a Non-Hydrostatic Wave Model". Water 11, nr 5 (10.05.2019): 986. http://dx.doi.org/10.3390/w11050986.

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In this work, internal wave generation techniques are developed in an open source non-hydrostatic wave model (Simulating WAves till SHore, SWASH) for accurate generation of regular and irregular long-crested waves. Two different internal wave generation techniques are examined: a source term addition method where additional surface elevation is added to the calculated surface elevation in a specific location in the domain and a spatially distributed source function where a spatially distributed mass is added in the continuity equation. These internal wave generation techniques in combination with numerical wave absorbing sponge layers are proposed as an alternative to the weakly reflective wave generation boundary to avoid re-reflections in case of dispersive and directional waves. The implemented techniques are validated against analytical solutions and experimental data including water surface elevations, orbital velocities, frequency spectra and wave heights. The numerical results show a very good agreement with the analytical solution and the experimental data indicating that SWASH with the addition of the proposed internal wave generation technique can be used to study coastal areas and wave energy converter (WEC) farms even under highly dispersive and directional waves without any spurious reflection from the wave generator.

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Suresh, P. "Analysis of Solar Power Generation Performance Improvement Techniques". IRO Journal on Sustainable Wireless Systems 4, nr 3 (15.09.2022): 212–21. http://dx.doi.org/10.36548/jsws.2022.3.008.

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The performance of solar power generation systems broadly depends upon the effectiveness of the solar cell placed in the architecture. The performance of the solar cell may vary with respect to the heat generated over its surface. Hence different types of cooling methods are employed over the solar power generation system to improve its power efficiency. Apart from solar cell cooling method, different types of optimization techniques are also implemented to the solar power generation unit for extracting a good power output. The maximum power point tracking algorithm is one of the primary methods used for matching the generated power to reach the required power in the connected battery system. The paper analyzes the research attainments and limitations of the various cooling models employed for the solar power generation system to develop an efficient system in future.

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Vansarochana, Anujit, Nitin K. Tripathi i Roberto Clemente. "Finding appropriate interpolation techniques for topographic surface generation for mudslide risk zonation". Geocarto International 24, nr 4 (sierpień 2009): 313–32. http://dx.doi.org/10.1080/10106040802547735.

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Benčina, Metka, Niharika Rawat, Katja Lakota, Snežna Sodin-Šemrl, Aleš Iglič i Ita Junkar. "Bio-Performance of Hydrothermally and Plasma-Treated Titanium: The New Generation of Vascular Stents". International Journal of Molecular Sciences 22, nr 21 (1.11.2021): 11858. http://dx.doi.org/10.3390/ijms222111858.

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The research presented herein follows an urgent global need for the development of novel surface engineering techniques that would allow the fabrication of next-generation cardiovascular stents, which would drastically reduce cardiovascular diseases (CVD). The combination of hydrothermal treatment (HT) and treatment with highly reactive oxygen plasma (P) allowed for the formation of an oxygen-rich nanostructured surface. The morphology, surface roughness, chemical composition and wettability of the newly prepared oxide layer on the Ti substrate were characterized by scanning electron microscopy (SEM) with energy-dispersive X-ray analysis (EDX), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and water contact angle (WCA) analysis. The alteration of surface characteristics influenced the material’s bio-performance; platelet aggregation and activation was reduced on surfaces treated by hydrothermal treatment, as well as after plasma treatment. Moreover, it was shown that surfaces treated by both treatment procedures (HT and P) promoted the adhesion and proliferation of vascular endothelial cells, while at the same time inhibiting the adhesion and proliferation of vascular smooth muscle cells. The combination of both techniques presents a novel approach for the fabrication of vascular implants, with superior characteristics.

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DUMAS, P., M. K. WELDON, Y. J. CHABAL i G. P. WILLIAMS. "MOLECULES AT SURFACES AND INTERFACES STUDIED USING VIBRATIONAL SPECTROSCOPIES AND RELATED TECHNIQUES". Surface Review and Letters 06, nr 02 (kwiecień 1999): 225–55. http://dx.doi.org/10.1142/s0218625x99000263.

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Recent developments in the major experimental vibrational-spectroscopic techniques (i.e. infrared absorption, Raman scattering, high resolution electron loss, helium atom scattering and sum frequency generation) are reviewed and illustrated with selected results. Particular emphasis is given to two important topics which have attracted much attention in recent years: (i) the complex surface reactions taking place on technologically relevant surfaces and interfaces, and (ii) vibrational dynamics with emphasis on energy dissipation at surfaces.

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Anuradha, K., Deekshitha Erlapally, G. Karuna, V. Srilakshmi i K. Adilakshmi. "Analysis Of Solar Power Generation Forecasting Using Machine Learning Techniques". E3S Web of Conferences 309 (2021): 01163. http://dx.doi.org/10.1051/e3sconf/202130901163.

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Solar power is generated using photovoltaic (PV) systems all over the world. Because the output power of PV systems is alternating and highly dependent on environmental circumstances, solar power sources are unpredictable in nature. Irradiance, humidity, PV surface temperature, and wind speed are only a few of these variables. Because of the unpredictability in photovoltaic generating, it’s crucial to plan ahead for solar power generation as in solar power forecasting is required for electric grid. Solar power generation is weather-dependent and unpredictable, this forecast is complex and difficult. The impacts of various environmental conditions on the output of a PV system are discussed. Machine Learning (ML) algorithms have shown great results in time series forecasting and so can be used to anticipate power with weather conditions as model inputs. The use of multiple machine learning, Deep learning and artificial neural network techniques to perform solar power forecasting. Here in this regression models from machine learning techniques like support vector machine regressor, random forest regressor and linear regression model from which random forest regressor beaten the other two regression models with vast accuracy.

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Girbacia, Teodora, Florin Girbacia i Gheorghe Mogan. "Virtual Planning of Robot Trajectories for Spray Painting Applications". Applied Mechanics and Materials 658 (październik 2014): 632–37. http://dx.doi.org/10.4028/www.scientific.net/amm.658.632.

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In this paper is presented a Virtual Reality application that can be used for automatic generation of robot trajectories for spray painting operations conducted on products with complex surfaces. The trajectory generation for robots that perform painting operations of complex curved surfaces was achieved by implementing a generic algorithm capable of maintaining an optimal distance for painting. The distance between the effecter of the robot and the surface of the CAD model, used to compensate and maintain an optimal painting distance, is determined by a "rayhit" collision detection algorithm that allows the detection of the contact between a linear segment and the mesh of the virtual object. To visualize in the virtual environment the deposition of paint layers, an algorithm was implemented that is based on mapping techniques for dynamically generated textures on the surface that is being painted. A VR software application was developed for generating and visualizing the trajectories of a KUKA robotic system that performs the activity of painting a complex curved product.

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T. V., Smitha, Madhura S, Sindhu R i Brundha R. "A Study on Various Mesh Generation Techniques used for Engineering Applications". Journal of Innovative Image Processing 3, nr 2 (2.06.2021): 75–84. http://dx.doi.org/10.36548/jiip.2021.2.001.

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In this paper our aim is to provide a survey of mesh generation techniques for some Engineering applications. Mesh generation is a very important requirement to solve any problem by very popular numerical method known as Finite element method (FEM). It has several applications in various fields. One such technique is Automated generation of finite element meshes for aircraft conceptual design. It’s an approach for automated generation of fully connected finite element meshes for all internal structural components, given wing body, geometry model, controlled by a few conceptual level structural layout parameters. Another application where it is used is in the study of biomolecules to generate volumetric mesh of a biomolecule of any size and shape based on its atomic structure. These methods are proved to be a faster method due to the usage of computing techniques. Mesh generator is also used for creating finite element surface and volumetric mesh from 3D binary and gray scale medical images. Some of the applications include volumetric images, surface mesh extraction, surface mesh repairing and many more. It is of great importance in understanding the human brain which is a complex subject. Though 3D visualization is a useful tool available, yet it is inadequate due to its challenging computational problem. This paper also includes the survey on latest tools used for these applications which overcomes many problems associated with the conventional approaches.

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Iviglia, Giorgio, i Marco Morra. "Engineering Interfacial Environment of Epigallocatechin Gallate Coated Titanium for Next-Generation Bioactive Dental Implant Components". International Journal of Molecular Sciences 24, nr 3 (31.01.2023): 2661. http://dx.doi.org/10.3390/ijms24032661.

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In view of endowing the surface of abutments, a component of titanium dental implant systems, with antioxidant and antimicrobial properties, a surface layer coated with epigallocatechin gallate (EGCg), a polyphenol belonging to the class of flavonoids, was built on titanium samples. To modulate interfacial properties, EGCg was linked either directly to the surface, or after populating the surface with terminally linked polyethyleneglycol (PEG) chains, Mw ~1600 Da. The underlying assumption is that fouling-resistant, highly hydrated PEG chains could reduce non-specific bioadhesion and magnify intrinsic EGCg properties. Treated surfaces were investigated by a panel of surface/interfacial sensitive techniques, to provide chemico–physical characterization of the surface layer and its interfacial environment. Results show: (i) successful EGCg coupling for both approaches; (ii) that both approaches endow the Ti surface with the same antioxidant properties; (iii) that PEG-EGCg coated surfaces are more hydrophilic and show a significantly higher (>50%) interaction force with water. Obtained results build up a rationale basis for evaluation of the merits of finely tuning interfacial properties of polyphenols coated surfaces in biological tests.

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Saito, Genki, i Tomohiro Akiyama. "Nanomaterial Synthesis Using Plasma Generation in Liquid". Journal of Nanomaterials 2015 (2015): 1–21. http://dx.doi.org/10.1155/2015/123696.

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Over the past few decades, the research field of nanomaterials (NMs) has developed rapidly because of the unique electrical, optical, magnetic, and catalytic properties of these materials. Among the various methods available today for NM synthesis, techniques for plasma generation in liquid are relatively new. Various types of plasma such as arc discharge and glow discharge can be applied to produce metal, alloy, oxide, inorganic, carbonaceous, and composite NMs. Many experimental setups have been reported, in which various parameters such as the liquid, electrode material, electrode configuration, and electric power source are varied. By examining the various electrode configurations and power sources available in the literature, this review classifies all available plasma in liquid setups into four main groups: (i) gas discharge between an electrode and the electrolyte surface, (ii) direct discharge between two electrodes, (iii) contact discharge between an electrode and the surface of surrounding electrolyte, and (iv) radio frequency and microwave plasma in liquid. After discussion of the techniques, NMs of metal, alloy, oxide, silicon, carbon, and composite produced by techniques for plasma generation in liquid are presented, where the source materials, reaction media, and electrode configurations are discussed in detail.

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Faran, K. J., R. J. Dwayne Miller i S. M. Gracewski. "Analysis of Surface Wave Generation by Laser Interference". Journal of Applied Mechanics 57, nr 2 (1.06.1990): 415–18. http://dx.doi.org/10.1115/1.2892005.

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An analytical solution for thermal excitation of elastic waves in an homogeneous, isotropic, elastic half-space resulting from a pulsed laser interference pattern incident on the solid surface is presented. The spacially-periodic laser field absorbed by the surface causes rapid heating within the optical penetration depth. Thus, a temperature field is generated which can be modeled as being spacially harmonic along the free edge, decaying exponentially with depth, and having a Heaviside dependence on time. Transform techniques yield expressions for the resulting transverse and normal displacements within the laser interference region in terms of infinite integrals over frequency. The integrands contain poles indicating the expected Rayleigh waves propagating along the surface, as well as branch points corresponding to the bulk longitudinal and transverse wave speeds. The solution is obtained by integrating numerically in the complex frequency plane with an appropriate contour around the poles and branch cuts. Normal and transverse displacements are plotted as functions of time and depth for various materials and temperature fields.

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Mei, Gang. "Summary on Several Key Techniques in 3D Geological Modeling". Scientific World Journal 2014 (2014): 1–11. http://dx.doi.org/10.1155/2014/723832.

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Several key techniques in 3D geological modeling including planar mesh generation, spatial interpolation, and surface intersection are summarized in this paper. Note that these techniques are generic and widely used in various applications but play a key role in 3D geological modeling. There are two essential procedures in 3D geological modeling: the first is the simulation of geological interfaces using geometric surfaces and the second is the building of geological objects by means of various geometric computations such as the intersection of surfaces. Discrete geometric surfaces that represent geological interfaces can be generated by creating planar meshes first and then spatially interpolating; those surfaces intersect and then form volumes that represent three-dimensional geological objects such as rock bodies. In this paper, the most commonly used algorithms of the key techniques in 3D geological modeling are summarized.

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Bhatt, Pankaj, Vipin Kumar, Vetriselvan Subramaniyan, Kandasamy Nagarajan, Mahendran Sekar, Suresh V. Chinni i Gobinath Ramachawolran. "Plasma Modification Techniques for Natural Polymer-Based Drug Delivery Systems". Pharmaceutics 15, nr 8 (1.08.2023): 2066. http://dx.doi.org/10.3390/pharmaceutics15082066.

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Natural polymers have attracted significant attention in drug delivery applications due to their biocompatibility, biodegradability, and versatility. However, their surface properties often limit their use as drug delivery vehicles, as they may exhibit poor wettability, weak adhesion, and inadequate drug loading and release. Plasma treatment is a promising surface modification technique that can overcome these limitations by introducing various functional groups onto the natural polymer surface, thus enhancing its physicochemical and biological properties. This review provides a critical overview of recent advances in the plasma modification of natural polymer-based drug delivery systems, with a focus on controllable plasma treatment techniques. The review covers the fundamental principles of plasma generation, process control, and characterization of plasma-treated natural polymer surfaces. It discusses the various applications of plasma-modified natural polymer-based drug delivery systems, including improved biocompatibility, controlled drug release, and targeted drug delivery. The challenges and emerging trends in the field of plasma modification of natural polymer-based drug delivery systems are also highlighted. The review concludes with a discussion of the potential of controllable plasma treatment as a versatile and effective tool for the surface functionalization of natural polymer-based drug delivery systems.

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Xia, Yuwei, Sang Wook Han i Hyock Ju Kwon. "Image Generation and Recognition for Railway Surface Defect Detection". Sensors 23, nr 10 (16.05.2023): 4793. http://dx.doi.org/10.3390/s23104793.

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Railway defects can result in substantial economic and human losses. Among all defects, surface defects are the most common and prominent type, and various optical-based non-destructive testing (NDT) methods have been employed to detect them. In NDT, reliable and accurate interpretation of test data is vital for effective defect detection. Among the many sources of errors, human errors are the most unpredictable and frequent. Artificial intelligence (AI) has the potential to address this challenge; however, the lack of sufficient railway images with diverse types of defects is the major obstacle to training the AI models through supervised learning. To overcome this obstacle, this research proposes the RailGAN model, which enhances the basic CycleGAN model by introducing a pre-sampling stage for railway tracks. Two pre-sampling techniques are tested for the RailGAN model: image-filtration, and U-Net. By applying both techniques to 20 real-time railway images, it is demonstrated that U-Net produces more consistent results in image segmentation across all images and is less affected by the pixel intensity values of the railway track. Comparison of the RailGAN model with U-Net and the original CycleGAN model on real-time railway images reveals that the original CycleGAN model generates defects in the irrelevant background, while the RailGAN model produces synthetic defect patterns exclusively on the railway surface. The artificial images generated by the RailGAN model closely resemble real cracks on railway tracks and are suitable for training neural-network-based defect identification algorithms. The effectiveness of the RailGAN model can be evaluated by training a defect identification algorithm with the generated dataset and applying it to real defect images. The proposed RailGAN model has the potential to improve the accuracy of NDT for railway defects, which can ultimately lead to increased safety and reduced economic losses. The method is currently performed offline, but further study is planned to achieve real-time defect detection in the future.

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Arnold, Thomas, Anne Maiwald, Georg Böhm, Martin Erhrhard i Klaus Zimmer. "Optical freeform generation by laser machining and plasma-assisted polishing". EPJ Web of Conferences 215 (2019): 03003. http://dx.doi.org/10.1051/epjconf/201921503003.

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Tailored optical freeform lenses are required for different applications. Sub-aperture deterministic machining techniques such as plasma jet machining have shown great potential to generate freeform surfaces. However, depending on the required local slopes of the surface shape geometrical limitations occur due to the lateral tool function width. In the paper an alternative approach to fabricate freeform shapes exhibiting steep local slopes is presented. A first step involves a dwell time based fs-laser ablation process to generate the surface contour on a fused silica sample. Since the resulting roughness after laser machining lies in the range of 400 nm RMS which does not match optical requirements a subsequent plasma jet based polishing step is performed where micro-roughness is drastically reduced to values below 0.3 nm RMS.

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CONRAD, EDWARD H. "THE STABILITY OF LOW INDEX METAL SURFACES TO TOPOLOGICAL DEFECTS". International Journal of Modern Physics B 05, nr 03 (10.02.1991): 427–59. http://dx.doi.org/10.1142/s0217979291000274.

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The study of defect formation at metal surfaces is a fundamental problem in surface physics. An understanding of defect formation is pertinent to growth and diffusion mechanisms. In addition, surface roughening, faceting, and surface melting are all defect mediated phase transitions involving the formation of different topological defects. While the importance of defects at surfaces is well recognized, the study of surface defects has been hampered by the lack of sufficiently accurate experimental techniques. In fact, it is only in the past 6 years that experiments on the thermal generation of defects on metal surfaces have been performed. This review attempts to outline both the theoretical and experimental work on surface defect formation on metal systems.

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Hoppe, Viktoria, Patrycja Szymczyk-Ziółkowska, Małgorzata Rusińska, Dominik Poradowski, Maciej Janeczek, Grzegorz Ziółkowski i Bogdan Dybała. "Study of cytotoxic activity of Ti–13Nb–13Zr medical alloy with different surface finishing techniques". Journal of Materials Science 56, nr 31 (20.08.2021): 17747–67. http://dx.doi.org/10.1007/s10853-021-06430-y.

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AbstractThe characterization of materials surface is essential, as the initial in vivo response is highly dependent on surface properties. Surface topography is a key aspect that influences the response of cells to products resulting from interaction with the surface of a titanium alloy, including parameters such as adhesion, spread, migration, proliferation, and differentiation of cells. Various surface modifications are used to improve the interface properties between MC3T3 and NHDF cells and the Ti–13Nb–13Zr-based surface. Among the techniques discussed in this paper, scanning electron microscopy, laser confocal scanning microscopy, and computed tomography are adequate to investigate materials topography at different scale levels. Chemical characterization of the outer layers of Ti–13Nb–13Zr samples was performed with X-ray photoelectron spectrometry. Studies have shown that the surfaces resulting from the treatment enabling the formation of titanium oxide and zirconium oxide show the lowest cytotoxicity. Implants made from the new generation of titanium alloy, not containing toxic elements, with the use of surface modification could be an essential innovation in implantology.

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Kenda, Klemen, Jože Peternelj, Nikos Mellios, Dimitris Kofinas, Matej Čerin i Jože Rožanec. "Usage of statistical modeling techniques in surface and groundwater level prediction". Journal of Water Supply: Research and Technology-Aqua 69, nr 3 (20.04.2020): 248–65. http://dx.doi.org/10.2166/aqua.2020.143.

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Abstract The paper presents a thorough evaluation of the performance of different statistical modeling techniques in ground- and surface-level prediction scenarios as well as some aspects of the application of data-driven modeling in practice (feature generation, feature selection, heterogeneous data fusion, hyperparameter tuning, and model evaluation). Twenty-one different regression and classification techniques were tested. The results reveal that batch regression techniques are superior to incremental techniques in terms of accuracy and that among them gradient boosting, random forest and linear regression perform best. On the other hand, introduced incremental models are cheaper to build and update and could still yield good enough results for certain large-scale applications.

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Velimirovic, Ljubica, Mica Stankovic i Grozdana Radivojevic. "Modeling conoid surfaces". Facta universitatis - series: Architecture and Civil Engineering 2, nr 4 (2002): 261–66. http://dx.doi.org/10.2298/fuace0204261v.

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In tins paper we consider conoid surfaces as frequently used surfaces in building techniques, mainly as daring roof structures. Different types of conoids are presented using the programme package Mathematica. We describe the generation of conoids and by means of parametric representation we get their graphics. The geometric approach offers a wide range of possibilities in the research of complicated spatial surface systems.

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Govindarajan, Tina, i Robin Shandas. "A Survey of Surface Modification Techniques for Next-Generation Shape Memory Polymer Stent Devices". Polymers 6, nr 9 (29.08.2014): 2309–31. http://dx.doi.org/10.3390/polym6092309.

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Ahn, Hyun S., i Allen J. Bard. "Switching Transient Generation in Surface Interrogation Scanning Electrochemical Microscopy and Time-of-Flight Techniques". Analytical Chemistry 87, nr 24 (grudzień 2015): 12276–80. http://dx.doi.org/10.1021/acs.analchem.5b03542.

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Fang, Hsu-Wei, Stephen M. Hsu i Jan V. Sengers. "Generation of narrowly distributed ultra-high-molecular-weight polyethylene particles by surface texturing techniques". Journal of Biomedical Materials Research 67B, nr 2 (29.10.2003): 741–49. http://dx.doi.org/10.1002/jbm.b.10067.

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Kundu, P., i B. N. Mandal. "Generation of Surface Waves Due to Initial Axisymmetric Surface Disturbance in Water with a Porous Bottom". International Journal of Applied Mechanics and Engineering 24, nr 3 (1.08.2019): 625–44. http://dx.doi.org/10.2478/ijame-2019-0039.

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Abstract A two-dimensional Cauchy Poisson problem for water with a porous bottom generated by an axisymmetric initial surface disturbance is investigated here. The problem is formulated as an initial value problem for the velocity potential describing the motion in the fluid. The Laplace and Hankel transform techniques have been used in the mathematical analysis to obtain the form of the free surface in terms of a multiple infinite integral. This integral is then evaluated asymptotically by the method of stationary phase. The asymptotic form of the free surface is depicted graphically in a number of figures for different values of the porosity parameter and for different types of initial disturbances.

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Tabares, Francisco L., i Ita Junkar. "Cold Plasma Systems and Their Application in Surface Treatments for Medicine". Molecules 26, nr 7 (28.03.2021): 1903. http://dx.doi.org/10.3390/molecules26071903.

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In this paper, a review of cold plasma setups and the physical and chemical processes leading to the generation of active species is presented. The emphasis is given to the interaction of cold plasmas with materials used in medical applications, especially medical implants as well as live cells. An overview of the different kinds of plasmas and techniques used for generation of active species, which significantly alter the surface properties of biomaterials is presented. The elemental processes responsible for the observed changes in the physio-chemical properties of surfaces when exposed to plasma are described. Examples of ongoing research in the field are given to illustrate the state-of-the-art at the more conceptual level.

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Ho, Chih-Hao, Cagatay Basdogan i Mandayam A. Srinivasan. "Efficient Point-Based Rendering Techniques for Haptic Display of Virtual Objects". Presence: Teleoperators and Virtual Environments 8, nr 5 (październik 1999): 477–91. http://dx.doi.org/10.1162/105474699566413.

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Computer haptics, an emerging field of research that is analogous to computer graphics, is concerned with the generation and rendering of haptic virtual objects. In this paper, we propose an efficient haptic rendering method for displaying the feel of 3-D polyhedral objects in virtual environments (VEs). Using this method and a haptic interface device, the users can manually explore and feel the shape and surface details of virtual objects. The main component of our rendering method is the “neighborhood watch” algorithm that takes advantage of precomputed connectivity information for detecting collisions between the end effector of a force-reflecting robot and polyhedral objects in VEs. We use a hierarchical database, multithreading techniques, and efficient search procedures to reduce the computational time such that the haptic servo rate after the first contact is essentially independent of the number of polygons that represent the object. We also propose efficient methods for displaying surface properties of objects such as haptic texture and friction. Our haptic-texturing techniques and friction model can add surface details onto convex or concave 3-D polygonal surfaces. These haptic-rendering techniques can be extended to display dynamics of rigid and deformable objects.

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McGILP, J. F. "SECOND-HARMONIC GENERATION AT SEMICONDUCTOR AND METAL SURFACES". Surface Review and Letters 06, nr 03n04 (czerwiec 1999): 529–58. http://dx.doi.org/10.1142/s0218625x99000494.

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Optical second-harmonic generation, although a sophisticated technique, is making a significant contribution to the characterization of surfaces and interfaces. The advantages include: all pressure ranges are accessible; insulators are studied without the problem of charging effects; solid–solid and solid–liquid interfaces are characterized by utilizing the large penetration depth of optical radiation. Single wavelength studies yield information on the crystallographic and magnetic structure of surfaces and interfaces, and are particularly sensitive to symmetry changes. Spectroscopic studies, which have recently become simpler due to the availability of high pulse power, tunable, broadband laser sources, additionally provide electronic structure information, although the interpretation of this may not be simple. In this review examples from well-characterized interfaces are emphasized, and it is shown that the technique is now well understood at the phenomenological level, although theoretical calculations are proving to be difficult. Interfaces not accessible to conventional surface techniques can now be studied with confidence.

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Anstey, James R., Peter R. Forrest, Helen Cass, Paul Emery, Christian Karcher, Megan Kelly, Lidgalem Mesfin, David Moore i Rinaldo Bellomo. "Sustained normothermia in septic shock and the energy transfer required: a report of a pilot feasibility study using newer-generation surface cooling devices". Critical Care and Resuscitation 23, nr 1 (1.03.2021): 113–16. http://dx.doi.org/10.51893/2021.1.rl1.

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There is significant uncertainty about the potential role of temperature control in the intensive care unit (ICU) in general, but more specifically in septic shock patients.1,2 Common techniques for temperature control have been limited by minimal effect (eg, paracetamol, fans or air blankets), undesirable side effects (eg, non-steroidal anti-inflammatories), or being burdensome (eg, heavy sedation, paralysis with surface cooling; intravascular cooling devices3). In contrast, the potential of newer-generation surface-cooling devices to achieve temperature control more simply has created the possibility of studying temperature modulation in the septic ICU population.

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Käppler, Iris, Rolf-Dieter Hund i Chokri Cherif. "Surface modification of carbon fibres using plasma technique". Autex Research Journal 14, nr 1 (14.03.2014): 34–38. http://dx.doi.org/10.2478/v10304-012-0048-y.

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Abstract For the development of a new generation non-crimp fabrics (NCF) made of carbon fibres, a feasibility study of different characterisation methods and surface treatments of the used carbon fibres needs to be performed. In order to join the carbon fibre layers with the binder for realising this new type of NCF, the surface topography and functionality of the fibres have to be analysed first. The wettability of the binder to the carbon fibre surface is of prime significance and needs to be enhanced. Here, the enhancement is carried out by improving the surface energy using atmospheric plasma of compressed air, argon and nitrogen. It is also proposed to improve the surface energy through chemical techniques.

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Wang, Dawei, Yang Zhao, Yixin He, Xiao Tang, Lixin Li, Ruonan Zhang i Daosen Zhai. "Passive Beamforming and Trajectory Optimization for Reconfigurable Intelligent Surface-Assisted UAV Secure Communication". Remote Sensing 13, nr 21 (25.10.2021): 4286. http://dx.doi.org/10.3390/rs13214286.

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Unmanned aerial vehicle (UAV) and reconfigurable intelligent surface (RIS) methods are promising techniques for improving the energy and spectrum efficiency of Fifth Generation/Beyond Fifth Generation (5G/B5G) networks. In order to take advantage of both techniques, we propose an RIS-assisted UAV secure communication scheme, where an UAV is equipped with RIS to facilitate secure transmission. To maximize the average secrecy rate, we jointly optimize the beamforming power, reflect phase shift, and UAV’s trajectory. For this non-convex problem, we decompose it into the power beamforming problem, the phase shift optimization problem, and the UAV’s trajectory design problem, and proposed an efficient iterative algorithm to solve the problem. The numerical results verify the superiority of the proposed scheme that can improve the average secure transmission rate by about 20% compared to that of Eavesdropping elimination methods.

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Deng, Hui, i Kazuya Yamamura. "Evaluation of Surface Roughness and Subsurface Damage of 4H-SiC Processed by Different Finishing Techniques". Key Engineering Materials 523-524 (listopad 2012): 19–23. http://dx.doi.org/10.4028/www.scientific.net/kem.523-524.19.

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Single crystal SiC is one of the most attractive semiconductor materials for next generation power device applications. However, it is very difficult to be precisely machined due to its high hardness and chemical inertness. We evaluated the machining characteristics of 4H-SiC using different processes including diamond abrasives lapping, chemical mechanical polishing (CMP) and plasma assisted polishing (PAP). Scratches were introduced through diamond abrasives lapping due to the high hardness of diamond, which resulted in the worsening of surface roughness. A damage layer was observed in the cross-sectional transmission electron microscopy (XTEM) images. A scratch-free surface was obtained through CMP, but it’s not atomically flat since step/terrace structure couldn’t be clearly observed. PAP was newly proposed for the finishing of difficult to machine materials. In PAP, water vapor plasma oxidation and soft abrasive polishing were repeatedly conducted. Ceria which is much softer than SiC was used as the abrasive material. PAP was proved very effective to achieve surfaces out of scratches. Also, due to the low hardness of ceria, no damage layers were introduced. The roughness of PAP processed surface was decreased to about 0.1 nm rms. The surface was also observed by XTEM, which proved an atomically flat surface without crystallographical damage was obtained.

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Page, G. J. "Rapid, parallel CFD grid generation using octrees". Aeronautical Journal 117, nr 1188 (luty 2013): 133–46. http://dx.doi.org/10.1017/s0001924000007910.

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Abstract As Large Eddy Simulation is increasingly applied to flows containing complex geometry, grid generation becomes difficult and time consuming when using software originally developed for RANS flow solvers. The traditional ‘pipeline’ approach of grid generation → solve → visualise entails the time consuming transfer of large files and conversion of file formats. This work demonstrates a grid generation methodology developed specifically to be integrated with parallel LES. The current approach is to use a Cartesian grid with adaptive refinement based upon geometry intersection, surface detail and surface curvature. The grid is defined by an octree data structure with the geometry defined by triangular facets using the STL file format. The result is a set of ‘cubical’ subdomains, each with identical numbers of cells and uniform distributions within the cube. Some subdomains will be entirely fluid and can be solved using straightforward CFD techniques, whilst some cubes will be cut by the surfaces. Individual cells are then tagged as ‘solid’, ‘fluid’ or ‘cut’ with the solver expected to use an immersed boundary approach to model the surface. A key feature is the design of the algorithm to be parallelisable on both shared and distributed memory systems. The distributed memory parallel dynamically partitions the grid as it is being generated, so that the partitioning is suitable for a subsequent flow solver. Grid generation testing has been carried out on a variety of input CAD files ranging up to 350,000 facets. A landing gear case shows how the grid generator correctly finds the fluid inside of the tire and other cavities within the hub. In scalar mode, a grid with 4,916 cubes and 468 million cells is generated in less than 100 seconds, whilst in parallel on 32 processor cores this can be achieved in 4·6 seconds.

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Guan, Yefeng, Huiru Zhang, Zhibin Yan, Xue Wei, Zhuo Zhang i Xuelian Chen. "Surface Modification of Cyclic-Olefin-Copolymer (COC)-Based Microchannels for the Large-Scale Industrial Production of Droplet Microfluidic Devices". Bioengineering 10, nr 7 (25.06.2023): 763. http://dx.doi.org/10.3390/bioengineering10070763.

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The copolymers of cycloolefin (COC), a type of thermoplastic material, have been widely used for the large-scale industrial fabrication of droplet microfluidic devices, which is often performed using hot-embossing or injection-molding techniques. The generation of droplets and the uniformity of droplet sizes are significantly affected by the surface wettability of COC during fabrication and the pressure stability of the employed fluid pump during operation. In order to alleviate the effects of undesirable surface wettability and pressure variation on the generation of droplets in COC-based devices, a simple surface modification procedure was applied to hydrophobically modify the surfaces of COC-based microchannels for large-scale industrial production. The surface modification procedure consisted of an oxygen plasma treatment of the polymer surface followed by a solution-phase reaction in fluorocarbon solvent. The experimental results demonstrate that following the proposed surface modification, the COC droplet microfluidic devices could stably generate microvolume water droplets with a small coefficient of variation, even if the pressure of the dispersed phase (water) fluctuated. The durability test results regarding the modified surfaces show that the hydrophobicity of the modified COC surfaces could be sustained for up to four months, deteriorating with time thereafter. Our study can provide a potential solution useful in and guidance for the large-scale industrial production of droplet microfluidic devices for various applications, including polymerase chain reaction and single-cell analysis.

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Speyerer, Christian, Kirsten Borchers, Joachim Storsberg, Günter E. M. Tovar, Thomas Hirth i Achim Weber. "Generation and Surface Functionalization of Electro Photographic Toner Particles for Biomaterial Applications". MRS Proceedings 1569 (2013): 165–71. http://dx.doi.org/10.1557/opl.2013.906.

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ABSTRACTIn this paper, we provide the investigation about the controlled surface functionalization of acrylic toner particles for electro photography (“laser printing”) with sodium hydroxide and the subsequent carbodiimide-mediated coupling of numerous functional amines onto the generated carboxylic group. Various chemically valuable functionalities, comprising of thiol, alkyne and azide, were bound onto the particles’ surface and allow for further versatile modifications via huisgen cycloaddition as well as thiol-ene reaction. The functionalization of the acrylic toner surface with alkyne, azide and carboxylic groups increased the cell viability up to 178 % ± 22 % and might offer an interesting path for new applications using common laser printing techniques.

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Mineo, Carmelo, Stephen Gareth Pierce, Pascual Ian Nicholson i Ian Cooper. "Introducing a novel mesh following technique for approximation-free robotic tool path trajectories". Journal of Computational Design and Engineering 4, nr 3 (16.02.2017): 192–202. http://dx.doi.org/10.1016/j.jcde.2017.01.002.

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Abstract Modern tools for designing and manufacturing of large components with complex geometries allow more flexible production with reduced cycle times. This is achieved through a combination of traditional subtractive approaches and new additive manufacturing processes. The problem of generating optimum tool-paths to perform specific actions (e.g. part manufacturing or inspection) on curved surface samples, through numerical control machinery or robotic manipulators, will be increasingly encountered. Part variability often precludes using original design CAD data directly for toolpath generation (especially for composite materials), instead surface mapping software is often used to generate tessellated models. However, such models differ from precise analytical models and are often not suitable to be used in current commercially available path-planning software, since they require formats where the geometrical entities are mathematically represented thus introducing approximation errors which propagate into the generated toolpath. This work adopts a fundamentally different approach to such surface mapping and presents a novel Mesh Following Technique (MFT) for the generation of tool-paths directly from tessellated models. The technique does not introduce any approximation and allows smoother and more accurate surface following tool-paths to be generated. The background mathematics to the new MFT algorithm are introduced and the algorithm is validated by testing through an application example. Comparative metrology experiments were undertaken to assess the tracking performance of the MFT algorithms, compared to tool-paths generated through commercial software. It is shown that the MFT tool-paths produced 40% smaller errors and up to 66% lower dispersion around the mean values. Highlights This work presents a technique for generation of tool-paths from tessellated models. The technique does not introduce approximations to surface following tool-paths. Comparative metrology experiments were carried out to assess the technique. The technique produces smaller errors and lower dispersion around the mean values. The developed method is aligned with the growing use of surface mapping techniques.

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Holder, Daniel, Matthias Buser, Artur Leis, Rudolf Weber i Thomas Graf. "Post-processing of additively manufactured metal parts by ultrashort laser pulses for high-quality net shape geometries and advanced functionality". IOP Conference Series: Materials Science and Engineering 1135, nr 1 (1.11.2021): 012005. http://dx.doi.org/10.1088/1757-899x/1135/1/012005.

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Abstract Additive manufacturing by means of laser-based powder bed fusion (LPBF) offers high flexibility with respect to the generation of individualized and light-weight metal parts. However, the produced parts are typically attached to support structures and deviate a few tens of micrometers from the targeted final component in geometrical net shape and surface roughness due to the melt-based fusion process. Therefore, different post-processing techniques were examined in the past to resolve the mentioned quality drawbacks. In our work, we investigated the potential of post-processing of LPBF-generated Ti6Al4V parts with ultrashort pulse laser ablation. As a result, the support structures were effectively removed, the surface roughness was reduced by 81% and complex geometries with high shape accuracy were fabricated. Furthermore, the LBPF-generated parts were laser surface structured to investigate the potential of post-processing with ultrashort laser pulses for advanced functionality, such as water-repellent surfaces. The generation of surface structures on the LPBF-generated Ti6Al4V part changed the wetting behaviour from hydrophilic to hydrophobic with an increased contact angle from 73° up to 130°.

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Ariaratnam, Samuel T., Erez N. Allouche i Kevin W. Biggar. "Testing of a new generation horizontal soil sampler". Canadian Geotechnical Journal 37, nr 1 (1.02.2000): 259–63. http://dx.doi.org/10.1139/t99-097.

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Sampling using horizontal directional drilling allows the collection of soil samples from suspected zones located beneath structures and other surface-subsurface obstacles. However, current horizontal sampling techniques are time consuming and thus expensive. This paper describes the design and testing of a new multiple-port sampler for collection of soil samples from directionally drilled boreholes. The device uses a new methodology for horizontal sampling to improve cost-effectiveness and sample quality.Key words: horizontal directional drilling, horizontal wells, design, remediation, site characterization, sampling.

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Patil, S., i Q. Guo. "STELLAR: A LARGE SATELLITE STEREO DATASET FOR DIGITAL SURFACE MODEL GENERATION". International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLVIII-M-1-2023 (14.06.2023): 433–40. http://dx.doi.org/10.5194/isprs-archives-xlviii-m-1-2023-433-2023.

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Abstract. Stellar is a large, satellite stereo dataset. It contains rectified stereo pairs of the terrain captured by the satellite image sensors and corresponding true disparity maps and semantic segmentation. Unlike stereo vision in autonomous driving and mobile imaging, a satellite stereo pair is not captured simultaneously. Thus, the same object in a satellite stereo pair is more likely to have a varied visual appearance. Stellar provides flexible access to such stereo pairs to train methods to be robust to such appearance variation. We use publicly available data sources, and invented several techniques to perform data registration, rectification, and semantic segmentation on the data to build Stellar. In our preliminary experiment, we fine-tuned two deep-learning stereo methods on Stellar. The result demonstrates that most of the time, these methods generate denser and more accurate disparity maps for satellite stereo by fine-tuning on Stellar, compared to without fine-tuning on satellite stereo datasets, or fine-tuning on previous, smaller satellite stereo datasets. Stellar is available to download at https://github.com/guo-research-group/Stellar.

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Alamri, Sabri, Fotis Fraggelakis, Tim Kunze, Benjamin Krupop, Girolamo Mincuzzi, Rainer Kling i Andrés Fabián Lasagni. "On the Interplay of DLIP and LIPSS Upon Ultra-Short Laser Pulse Irradiation". Materials 12, nr 7 (27.03.2019): 1018. http://dx.doi.org/10.3390/ma12071018.

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Controlling laser induced surface morphology is essential for developing specialized functional surfaces. This work presents novel, multi-scale periodic patterns with two-dimensional symmetry generated on stainless steel, polyimide and sapphire. The microstructures were realized by combining Direct Laser Interference Patterning with the generation of Laser Induced Periodic Surface Structures in a one-step process. An industrial, fiber femtosecond laser source emitting at 1030 nm with a pulse duration of 500 fs was utilized for the experiments. In the case of stainless steel, it was possible to create line-like or pillar-like surface patterns by rotating the polarization orientation with respect to the interference pattern. In the case of polyimide and sapphire, the absorption of the laser radiation was promoted by a multiphoton mechanism. In polyimide, grooves and pillars of several microns in depth were produced over an area much larger than the spot size. Finally, for sapphire, the simultaneous generation of interference-like pattern and laser induced periodic surface structures was realized. The results reported here provide valuable data on the feasibility to combine two state-of-the-art techniques with an industrial apparatus, to control the induced surface morphology.

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Wang, Zhenfeng. "Fabrication Techniques for Production of Thermoplastic-Based Microfluidics Devices". Journal of Molecular and Engineering Materials 04, nr 03 (wrzesień 2016): 1640016. http://dx.doi.org/10.1142/s2251237316400165.

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Microfluidics is a multidisciplinary technology which enables the face-lift crossing a wide range of applications such as life science research, point-of-care diagnostics and personal medicine. Polymer materials, especially thermoplastics, are dominating this emerging market due to the low material cost and the ease of mass production. This paper reviews the major fabrication technologies for making polymer, especially thermoplastic microfluidic chips, such as micro tooling, injection molding, bonding and surface treatment. The paper also summarizes the key challenges in fulfilling the needs of next generation microfluidic products.

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