Academic literature on the topic 'Full tip imaging in APT'
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Journal articles on the topic "Full tip imaging in APT"
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Du, Sichao, Timothy Burgess, Shyeh Tjing Loi, Baptiste Gault, Qiang Gao, Peite Bao, Li Li, et al. "Full tip imaging in atom probe tomography." Ultramicroscopy 124 (January 2013): 96–101. http://dx.doi.org/10.1016/j.ultramic.2012.08.014.
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Barroo, Cédric, Austin J. Akey, and David C. Bell. "Atom Probe Tomography for Catalysis Applications: A Review." Applied Sciences 9, no. 13 (July 5, 2019): 2721. http://dx.doi.org/10.3390/app9132721.
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Atom probe tomography is a well-established analytical instrument for imaging the 3D structure and composition of materials with high mass resolution, sub-nanometer spatial resolution and ppm elemental sensitivity. Thanks to recent hardware developments in Atom Probe Tomography (APT), combined with progress on site-specific focused ion beam (FIB)-based sample preparation methods and improved data treatment software, complex materials can now be routinely investigated. From model samples to complex, usable porous structures, there is currently a growing interest in the analysis of catalytic materials. APT is able to probe the end state of atomic-scale processes, providing information needed to improve the synthesis of catalysts and to unravel structure/composition/reactivity relationships. This review focuses on the study of catalytic materials with increasing complexity (tip-sample, unsupported and supported nanoparticles, powders, self-supported catalysts and zeolites), as well as sample preparation methods developed to obtain suitable specimens for APT experiments.
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Rice, Katherine P., Yimeng Chen, Ty J. Prosa, and David J. Larson. "Implementing Transmission Electron Backscatter Diffraction for Atom Probe Tomography." Microscopy and Microanalysis 22, no. 3 (June 2016): 583–88. http://dx.doi.org/10.1017/s1431927616011296.
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AbstractThere are advantages to performing transmission electron backscattering diffraction (tEBSD) in conjunction with focused ion beam-based specimen preparation for atom probe tomography (APT). Although tEBSD allows users to identify the position and character of grain boundaries, which can then be combined with APT to provide full chemical and orientation characterization of grain boundaries, tEBSD can also provide imaging information that improves the APT specimen preparation process by insuring proper placement of the targeted grain boundary within an APT specimen. In this report we discuss sample tilt angles, ion beam milling energies, and other considerations to optimize Kikuchi diffraction pattern quality for the APT specimen geometry. Coordinated specimen preparation and analysis of a grain boundary in a Ni-based Inconel 600 alloy is used to illustrate the approach revealing a 50° misorientation and trace element segregation to the grain boundary.
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Stadler, Johannes, Thomas Schmid, Lothar Opilik, Phillip Kuhn, Petra S. Dittrich, and Renato Zenobi. "Tip-enhanced Raman spectroscopic imaging of patterned thiol monolayers." Beilstein Journal of Nanotechnology 2 (August 30, 2011): 509–15. http://dx.doi.org/10.3762/bjnano.2.55.
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Full spectroscopic imaging by means of tip-enhanced Raman spectroscopy (TERS) was used to measure the distribution of two isomeric thiols (2-mercaptopyridine (2-PySH) and 4-mercaptopyridine (4-PySH)) in a self-assembled monolayer (SAM) on a gold surface. From a patterned sample created by microcontact printing, an image with full spectral information in every pixel was acquired. The spectroscopic data is in good agreement with the expected molecular distribution on the sample surface due to the microcontact printing process. Using specific marker bands at 1000 cm−1 for 2-PySH and 1100 cm−1 for 4-PySH, both isomers could be localized on the surface and semi-quantitative information was deduced from the band intensities. Even though nanometer size resolution information was not required, the large signal enhancement of TERS was employed here to detect a monolayer coverage of weakly scattering analytes that were not detectable with normal Raman spectroscopy, emphasizing the usefulness of TERS.
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Neyaz, Zafar. "Soft-Tip Stylet and Saline Instillation Technique: Making Difficult Percutaneous CT-Guided Biopsies Possible." Indian Journal of Radiology and Imaging 31, no. 04 (October 2021): 956–60. http://dx.doi.org/10.1055/s-0041-1741094.
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AbstractFinding a safe needle path during percutaneous computed tomography-guided biopsy is sometimes difficult due to concern for injuring a vital structure. Saline instillation technique has been used to displace the structure out of the way. Another useful tool is a soft-tip stylet. A soft-tip also referred as blunt-tip stylet for the introducer cannula is provided with some coaxial biopsy sets in additional to standard sharp-tip stylet. While the sharp-tip stylet is fitted with introducer cannula for piercing skin, muscle, and fascia, a soft-tip stylet may be used for avoiding injury to structures like vessels and bowel loops especially while advancing introducer cannula through fatty tissue. Additionally, it is also useful for avoiding injury to nerves and giving pleural anesthesia. Although its use has been described in medical literature, many radiologists are still not utilizing this tool to its full potential. In this educational exhibit, various applications of soft-tip stylet and saline instillation technique have been depicted using representative cases.
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Raffel, Markus, James T. Heineck, Edward Schairer, Friedrich Leopold, and Kolja Kindler. "Background-Oriented Schlieren Imaging for Full-Scale and In-Flight Testing." Journal of the American Helicopter Society 59, no. 1 (January 1, 2014): 1–9. http://dx.doi.org/10.4050/jahs.59.012002.
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Background-oriented schlieren (BOS) methods suited for large-scale and in-flight testing are presented with special emphasis on the detection and tracing of blade tip vortices in situ. Retroreflective recording and photogrammetric epipolar analysis for the computation of the vortices' spatial coordinates in the wind tunnel are described. Feasibility and fidelity of reference-free BOS in conjunction with natural formation backgrounds and related evaluation methods are discussed, additionally, illustrating their simplicity and robustness. Results of successful image acquisition from a chaser aircraft are presented allowing vortex wakes to be identified at a wide range of flight attitudes, including complex maneuvers.
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Fleischer, Monika. "Near-field scanning optical microscopy nanoprobes." Nanotechnology Reviews 1, no. 4 (August 1, 2012): 313–38. http://dx.doi.org/10.1515/ntrev-2012-0027.
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AbstractNear-field scanning optical microscopy (NSOM) is a powerful method for the optical imaging of surfaces with a resolution down to the nanometer scale. By focusing an external electromagnetic field to the subwavelength aperture or apex of a sharp tip, the diffraction limit is avoided and a near-field spot with a size on the order of the aperture or tip diameter can be created. This point light source is used for scanning a sample surface and recording the signal emitted from the small surface area that interacts with the near field of the probe. In tip-enhanced Raman spectroscopy, such a tip configuration can be used as well to record a full spectrum at each image point, from which chemically specific spectral images of the surface can be extracted. In either case, the contrast and resolution of the images depend critically on the properties of the NSOM probe used in the experiment. In this review, an overview of eligible tip properties and different approaches for tailoring specifically engineered NSOM probes is given from a fabrication point of view.
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Lübbe, Jannis, Matthias Temmen, Philipp Rahe, and Michael Reichling. "Noise in NC-AFM measurements with significant tip–sample interaction." Beilstein Journal of Nanotechnology 7 (December 1, 2016): 1885–904. http://dx.doi.org/10.3762/bjnano.7.181.
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The frequency shift noise in non-contact atomic force microscopy (NC-AFM) imaging and spectroscopy consists of thermal noise and detection system noise with an additional contribution from amplitude noise if there are significant tip–sample interactions. The total noise power spectral density D Δ f (f m) is, however, not just the sum of these noise contributions. Instead its magnitude and spectral characteristics are determined by the strongly non-linear tip–sample interaction, by the coupling between the amplitude and tip–sample distance control loops of the NC-AFM system as well as by the characteristics of the phase locked loop (PLL) detector used for frequency demodulation. Here, we measure D Δ f (f m) for various NC-AFM parameter settings representing realistic measurement conditions and compare experimental data to simulations based on a model of the NC-AFM system that includes the tip–sample interaction. The good agreement between predicted and measured noise spectra confirms that the model covers the relevant noise contributions and interactions. Results yield a general understanding of noise generation and propagation in the NC-AFM and provide a quantitative prediction of noise for given experimental parameters. We derive strategies for noise-optimised imaging and spectroscopy and outline a full optimisation procedure for the instrumentation and control loops.
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Paulite, Melissa, Carolin Blum, Thomas Schmid, Lothar Opilik, Klaus Eyer, Gilbert C. Walker, and Renato Zenobi. "Full Spectroscopic Tip-Enhanced Raman Imaging of Single Nanotapes Formed from β-Amyloid(1–40) Peptide Fragments." ACS Nano 7, no. 2 (January 22, 2013): 911–20. http://dx.doi.org/10.1021/nn305677k.
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Murray, Kermit K., Suman Ghorai, and Chinthaka A. Seneviratne. "Tip Enhanced Laser Ablation Sample Transfer for Mass Spectrometry." MRS Proceedings 1754 (2015): 87–95. http://dx.doi.org/10.1557/opl.2015.286.
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ABSTRACTMass spectrometry is one of the primary analysis techniques for biological analysis but there are technological barriers in sampling scale that must be overcome for it to be used to its full potential on the size scale of single cells. Current mass spectrometry imaging methods are limited in spatial resolution when analyzing large biomolecules. The goal of this project is to use atomic force microscope (AFM) tip enhanced laser ablation to remove material from cells and tissue and capture it for subsequent mass spectrometry analysis. The laser ablation sample transfer system uses an AFM stage to hold the metal-coated tip at a distance of approximately 10 nm from a sample surface. The metal tip acts as an antenna for the electromagnetic radiation and enables the ablation of the sample with a spot size much smaller than a laser focused with a conventional lens system. A pulsed nanosecond UV or visible wavelength laser is focused onto the gold-coated silicon tip at an angle nearly parallel with the surface, which results in the removal of material from a spot between 500 nm and 1 µm in diameter and 200 and 500 nm deep. This corresponds to a few picograms of ablated material, which can be captured on a metal surface for MALDI analysis. We have used this approach to transfer small peptides and proteins from a thin film for analysis by mass spectrometry as a first step toward high spatial resolution imaging.
Dissertations / Theses on the topic "Full tip imaging in APT"
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Du, Sichao. "Atom probe microscopy of III-V semiconductor nanowires." Thesis, The University of Sydney, 2013. http://hdl.handle.net/2123/10219.
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Group III-V semiconductor nanowires, showing novel properties, are promising building blocks for future applications. However, characterisation of individual NWs at the atomic level, which remains challenging, is critical to understand the detail growth mechanism. Therefore, this doctoral research aims, to develop a characterisation technique amenable to the specific configuration of a single nanowire, and to apply this technique to understand III-V nanowire growth. First, we developed a unique atom probe microscopy technique for directly measuring pristine nanowires on the growth substrate, which allows avoiding any damage introduced during sample preparation. Both experimental results and electrostatic simulations demonstrate the viability of this measuring approach to image the entire cross-section of a specimen, termed full tip imaging. Second, we characterised the distribution and relative concentration of dopants. The reconstruction parameters were determined based on crystallographic features. Background noises were removed based on multiple detector events. The concentration profile shows the dopants distributing radially inhomogeneous. Third, we investigated the vapour-liquid-solid and vapour-solid growth components in individual ternary InGaAs nanowires. A Ga-enriched core and In-enriched shell structure in the InGaAs nanowire has been found, which can essentially be related to the different growth mechanisms. This doctoral research advanced the atom probe microscopy characterisation of III-V nanowires. It developed a way to measure the pristine nanowire and increased the field-of-view by using the unique specimen preparation method. The atom probe microscopy results offer important compositional and structural information for the understanding of nanowire growth in order to realize applications in the future.
Conference papers on the topic "Full tip imaging in APT"
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Hashemi, Sayyed H., Ian C. Howard, John R. Yates, Robert M. Andrews, and Alan M. Edwards. "A Single Specimen CTOA Test Method for Evaluating the Crack Tip Opening Angle in Gas Pipeline Steels." In 2004 International Pipeline Conference. ASMEDC, 2004. http://dx.doi.org/10.1115/ipc2004-0610.
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Failure information from recent full-scale burst experiments on modern TMCP gas pipeline steels having a yield strength level of 690MPa and higher has shown that the CTOA fracture criterion can be effectively used to predict the arrest/propagation behaviour of the pipe against possible axial ductile fractures. The use of CTOA as an alternative or an addition to the Charpy V-notch and DWTT fracture energy in pipelines is currently under review. A significant difficulty currently limiting the more extensive use of CTOA in pipeline assessment is its practical evaluation either in the real structure or in a laboratory scale test. Different combinations of experimental and finite element analyses have been proposed for the measurement of the CTOA of a material. Although most of these models are able to predict the CTOA effectively, their implementation requires extensive calibration processes using the test load-deflection data. The authors have recently developed a novel test technique for direct measurement of the steady state CTOA using a modified double cantilever beam geometry. The technique uses optical imaging to register the uniform deformation of a fine square grid scored on the sides of the specimen. The slope of the deformed gridlines near the crack tip is measured during crack growth from captured images. Its value is a representative of the material CTOA. This paper presents recent results from the implementation of the technique to determine the steady state CTOA (steady state in this work refers to regions of ductile crack growth where CTOA values are constant and independent of crack length) of API X80 and X100 grade gas pipeline steels. In each case the approach was able to produce large amounts of highly consistent CTOA data from both sides of the test sample even from a single specimen. This extensive data set allowed an evaluation of the variance of the stable CTOA as the crack grew through the microstructure. The test method generated a steady CTOA value of 11.1° for X80 and 8.5° for X100 steels tested, respectively.
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Wolf, C., Johannes Braukmann, Stefan Koch, Markus Raffel, Clemens Schwarz, and Armin Weiss. "Wake Unsteadiness and Tip Vortex System of Full-Scale Helicopters in Ground Effect." In Vertical Flight Society 77th Annual Forum & Technology Display. The Vertical Flight Society, 2021. http://dx.doi.org/10.4050/f-0077-2021-16711.
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The main rotor wake of free–flying helicopters in ground effect was investigated during a measurement campaign with the DLR test rotorcraft Airbus Bo105 and EC135. An advanced measurement system combined high–speed schlieren imaging with point–wise constant temperature anemometry for a comprehensive analysis of the flow. In hover conditions, the wake structure was similar to earlier data, in spite of the environmental conditions, which were found to have a significant influence. The schlieren system tracked the blade tip vortices convecting along the slipstream boundary. Depending on the rotorcraft, the vortices developed either instabilities of individual filaments or cooperative pairing instabilities. Both instability types occurred one to two revolutions below the rotor plane, and the decayed tip vortices fell below the schlieren sensitivity limit soon after. The velocity footprint of the vortices was detected by fiber–film sensors further downstream along the slipstream boundary, but harmonic oscillations play a minor role in comparison to broad–banded turbulence with a Kolmogorov–like spectrum. The wake was found to be hover–like for vertical take–off cases until breaking down into low–frequency oscillations when exceeding a hub height of approximately 1.4 rotor radii. In forward flight conditions, blade–vortex interactions were found in the frontal area of the main rotor plane, and between the main rotor tip vortices and the Bo105’s tail rotor.
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Fan, Tai-Hsi, and Andrei G. Fedorov. "Electrohydrodynamics and Surface Force Analysis in AFM Imaging of a Charged, Deformable Biological Membrane in a Dilute Electrolyte Solution." In ASME/JSME 2003 4th Joint Fluids Summer Engineering Conference. ASMEDC, 2003. http://dx.doi.org/10.1115/fedsm2003-45152.
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Surface forces arising in AFM imaging of a deformable, negatively charged biological membrane in an electrolyte solution are investigated in the limit of continuous electrohydrodynamics. Specifically, we extend our previous analysis [1] of purely hydrodynamic interactions between an AFM tip and the elastic cell membrane by accounting for electric double-layer forces under the assumption of a dilute electrolyte solution and local electrochemical equilibrium. The solution of the problem is obtained by integrating the quasisteady, electrically-forced Stokes equation for the electrohydrodynamic field, the linearized Poisson-Boltzmann equation for the electrostatic field in the electrolyte inside and outside of the cell, and the Laplace equation for the electrostatic field within a dielectric AFM tip. The Helfrich and Zhongcan’s equation for an equilibrium shape of the cell membrane is employed as a quasi-steady, nonlinear boundary condition linking the stress fields on both sides of the cell membrane augmented by the local membrane incompressibility condition in order to find the local tension/compression force acting on the membrane. For the first time, an integrated framework for the dynamic coupling of the membrane double-layer effects and the AFM tip-electrolyte-membrane motion is established that allows for characterizing of the local electrolyte flow field, the electrostatic field, the elastic deformation of the membrane, and the electrohydrodynamic surface force acting on the AFM tip in great detail. The results of the analysis provide information on the motion of the membrane and the surface forces induced by both an electrolyte motion and the Maxwell stresses resulting from the charge double-layer screening effect for a full cycle motion of the AFM tip in a non-contact mode imaging of the cell membrane.
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Haines, Harvey, Lars Hörchens, and Jasper Schouten. "Adaptive Ultrasonic Imaging of Electric Resistance Welded Pipeline Seams." In 2018 12th International Pipeline Conference. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/ipc2018-78189.
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Imaging techniques using full matrix capture (FMC) ultrasonic NDE are well suited for in-service examination of electric resistance welded (ERW) pipe seams. We have been involved in developing an imagine technique since 2013 and presented results from Phase I at IPC in 2016 showing the system capable of detecting seam weld and SCC flaws and determining their orientation. The advantages over other methods such as phased array (PA) is the ability to image the flaw surface in addition to the flaw tip and corners where the flaw intersects the pipeline surface. This improves the ability to determine flaw orientation for discrimination of different types or crack-like features. The system produces UT images by overlaying multiple modes using reflections off the ID and OD pipe surface for ultrasonic illumination of the weld area from different directions. Using multiple modes produces a reflection off features regardless of flaw orientation from at least one of the modes. A complementary mode can then be used to size each feature by detecting the tips or ends of the feature from lower amplitude diffraction signals. Phase I used a model which assumed a cylindrical pipe shape. Real world use of this technique found limitations when pipe deviated from the assumed cylindrical shape such as severe offset plate edges, flat spots which can be the result of poor crimping adjacent the seam weld, or thickening of the seam caused by post weld heat treatment. In Phase II a need for reduced sizing error led to improved calibration and more advanced processing. To compensate for the non-perfect nature of real pipe, a new adaptive IWEX technique was developed to improve focusing and alignment of the various modes using the actual geometry to construct better focusing laws. First the OD and ID surfaces are imaged and the resulting surfaces are used to construct focusing laws which adapt to changes in the OD and ID surfaces. Results are better aligned UT images with the ability to image complex flaws with changes in orientation, and the ability to discriminate complex flaws from multiple small flaws in the pipe. Results show improvements in pipe with the greatest improvements in pipe with the largest deviations from a cylindrical shape.
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Bosetti, Paolo, and Francesco Biral. "Rapid Development of a CNC Software Within Manufacturing Automation Courses." In ASME 2008 International Mechanical Engineering Congress and Exposition. ASMEDC, 2008. http://dx.doi.org/10.1115/imece2008-68420.
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A significant part of a Manufacturing Automation course is devoted to CNC machine tools, their architecture, and the part programming languages (APT, ISO G-code and so on). Nevertheless, it is not trivial to provide the students with a complete understanding of the relationships between the machine dynamics, the path planning strategy, and the control systems. For this reason, a short laboratory course has been developed aimed at the programming of a simplified CNC software with the following functionalities: to parse a part program written in a subset of the ISO G-code; to process the instruction blocks and to generate trapezoidal velocity profiles; to convert the velocity profiles reference trajectory; to interpolate the reference trajectory at the servo loop control frequency. In order to shorten the development time, the following choices have been made. The parser only implements a small subset of the ISO G-code, which is point-to-point positioning (G00), linear interpolation (G01) and full stop (M30). The velocity profiles are calculated as acceleration-limited trapezoidal profiles with zero-feed velocity boundary conditions. Finally, the system is developed in Ruby, which is an object-oriented scripting language, easy to learn and well suited for rapid prototyping of complex software systems. This is why the project has been named RNC (Ruby Numerical Control). At the course start, the overall system architecture is explained and is translated in the set of Ruby classes that have to be developed, and classes interfaces are mandatorily determined. During the laboratory activity, students work in teams, and each team is encouraged to work separately on the development of each Ruby class. At the end of the development phase, the students can interface the RNC they wrote with a machine tool simulator (developed separately) and use the whole software system to test the accuracy of the tool-tip trajectories as a function of the system parameters (servo loop gains, motors torque, masses and dynamic performance of the virtual machine tool). Moreover, thanks to the object-based architecture of RNC and to the common, pre-determined class interfaces, the students can then swap and mix different implementations of the above reported functionalities, as well as enhanced versions provided by the teacher. With respect to other similar Mathlab/Simulink based solutions, the presented laboratory activity brings a more detailed insight into a CNC software still limiting the code complexity thanks to the Ruby language and it is only based on open-source tools.
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Hsu, C. P., N. E. Jewell-Larsen, A. C. Rollins, I. A. Krichtafovitch, S. W. Montgomery, J. T. Dibene, and A. V. Mamishev. "Miniaturization of Electrostatic Fluid Accelerators." In ASME 2006 International Mechanical Engineering Congress and Exposition. ASMEDC, 2006. http://dx.doi.org/10.1115/imece2006-13990.
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Existing thermal management methods for electronics do not meet technology needs and remain a major bottleneck in the evolution of computing, sensing, and information technology. The decreasing size of microelectronics components and the resulting increasing thermal output density require novel cooling solutions. Electrohydrodynamic ionic wind pumps, also known as electrostatic fluid accelerators (EFA), have the potential of becoming a critical element of electronic thermal management solutions. In order to take full advantage of EFA-based thermal management, it is essential to miniaturize EFA technology. This paper demonstrates the successful operation of a meso-scale microfabricated silicon EFA. A cantilever structure fabricated in bulk silicon with a radius of tip curvature of 25 μm is used as the corona electrode. The device was fabricated using a Deep Reactive Ion Etching (DRIE) microfabrication process. Forced convection cooling is demonstrated using infrared imaging, showing a 25°C surface temperature reduction over an actively heated substrate. The fabrication and test results of a meso-scale microfabricated EFA are presented in this paper.
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Siw, Sin Chien, Minking K. Chyu, and Mary Anne Alvin. "Effects of Pin Detached Space on Heat Transfer in a Rib Roughened Channel." In ASME 2011 Turbo Expo: Turbine Technical Conference and Exposition. ASMEDC, 2011. http://dx.doi.org/10.1115/gt2011-46078.
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An experimental study is performed to investigate the heat transfer characteristics and frictional losses in a rib roughened walls combined with detached pin-fins. The overall channel geometry (W = 76.2 mm, E = 25.4 mm) simulates an internal cooling passage of wide aspect ratio (3:1) in a gas turbine airfoil. With a given pin diameter, D = 6.35 mm = 1/4E, three different pin-fin height-to-diameter ratios, H/D = 4, 3, and 2, were examined. Each of these three cases corresponds to a specific pin array geometry of detachment spacing (C) between the pin-tip and one of the endwalls, i.e. C/D = 0, 1, 2, respectively. The rib height-to-channel height ratio is 0.0625. Two newly proposed cross-ribs, namely the broken ribs and full ribs are evaluated in this effort. The broken ribs are positioned in between two consecutive rows of pin-fins, while the full ribs are fully extended adjacent to the pin fins. The Reynolds number, based on the hydraulic diameter of the unobstructed cross-section and the mean bulk velocity, ranges from 10,000 to 25,000. The experiment employs a hybrid technique based on transient liquid crystal imaging to obtain distributions of the local heat transfer coefficient over all of the participating surfaces, including the endwalls and all the pin elements. The presence of ribs has enhanced the local heat transfer coefficient on the endwall substantially by about 20% up to 50% as compared to the neighboring endwall. In addition, affected by the rib geometry, which is a relatively low profile as compared to the overall height of the channel, the pressure loss seems to be insensitive to the presence of the ribs. However, from the overall heat transfer enhancement standpoint, the baseline cases (without ribs) outperforms cases with broken ribs and full ribs.
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Lall, Pradeep, Mandar Kulkarni, Sandeep Shantaram, and Jeff Suhling. "SIF Evaluation Using XFEM and Line Spring Models Under High Strain Rate Environment for Leadfree Alloys." In ASME 2011 Pacific Rim Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Systems. ASMEDC, 2011. http://dx.doi.org/10.1115/ipack2011-52196.
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In this paper, fracture properties of Sn3Ag0.5Cu leadfree high strain-rate solder-copper interface have been evaluated and validated with those from experimental methods. Bi-material Copper-Solder specimen have been tested at strain rates typical of shock and vibration with impact-hammer tensile testing machine. Models for crack initiation and propagation have been developed using Line spring method and extended finite element method (XFEM). Critical stress intensity factor for Sn3Ag0.5Cu solder-copper interface have been extracted from line spring models. Displacements and derivatives of displacements have been measured at crack tip and near interface of bi-material specimen using high speed imaging in conjunction with digital image correlation. Specimens have been tested at strain rates of 20s−1 and 55s−1 and the event is monitored using high speed data acquisition system as well as high speed cameras with frame rates in the neighborhood of 300,000 fps. Previously the authors have applied the technique of XFEM and DIC for predicting failure location and to develop constitutive models in leaded and few leadfree solder alloys [Lall 2010a]. The measured fracture properties have been applied to prediction of failure in ball-grid arrays subjected to high-g shock loading in the neighborhood of 12500g in JEDEC configuration. Prediction of fracture in board assemblies using explicit finite element full-field models of board assemblies under transient-shock is new. Stress intensity factor at Copper pad and bulk solder interface is also evaluated in ball grid array packages.
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Wardaya, P. D. "Characterizing the Seismic Response of Naturally Fractured Basement Reservoir in Sumatra Area: Towards an Efficient Seismic Exploration Strategy." In Indonesian Petroleum Association 44th Annual Convention and Exhibition. Indonesian Petroleum Association, 2021. http://dx.doi.org/10.29118/ipa21-g-261.
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Although only contributes few to the total oil and gas production, fractured basement reservoir is one of the important unconventional reservoirs in Indonesia. It was estimated that the gas reserve in basement in South Sumatra is about 6 TCF (trillion cubic feet). Most of the existing geophysical methods is not intended to explore events within the basement. In fact, majority of basement reservoir discovery was coincident. Despite its significant contribution to Indonesia’s gas production, the exploration success story in the fractured basement play is still poorly documented. The challenges and difficulties in their characterization are higher than the conventional reservoir. This study presents an integrated geological and geophysical approach to improve the outcome of seismic imaging of the fractured basement reservoir. A comprehensive geological study and geophysical modelling were conducted to provide an efficient strategy for designing an optimum seismic survey in imaging the fractures within the basement. Both surface and subsurface data were thoroughly analyzed to yield a reliable representation of the subsurface fracture model at basement level. Outcrop sample analysis combined with aerial remote sensing analysis were performed as input to digital outcrop modelling. The modelling was intended to provide information about fracture orientation, length, and density. This will provide a fracture property in the surface which is related to the fracture properties in subsurface. The resulting fracture properties was then used as an input to evaluate the seismic wave response during its propagation in the reservoir. Seismic modelling has been done using a 2D finite-difference full wavefield approach in a Graphics Processing Unit (GPU) accelerated computing system. We observe how fracture properties affect the propagating seismic wavefield. Wave scattering is observed more prominently around the fracture tip when the fracture plane is orthogonal to wavefield direction.
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Moles, Michael, and Simon Labbe´. "A Complete Solution for Weld Inspections: Phased Arrays and Diffraction Sizing." In ASME 2007 Pressure Vessels and Piping Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/creep2007-26579.
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Welds have been inspected by radiography for years, but this technology has major drawbacks: low detection rates for critical planar defects (i.e. cracks and lack of fusion), subjective interpretation, no vertical sizing capability, significant safety hazards, licensing issues, plant closures, and is generally slow. For decades, the main alternative was manual ultrasonics, which is also slow, subjective and normally has little hardcopy record. New technology and techniques are now available for improved weld inspections, specifically phased array technology and diffraction techniques. Phased arrays are essentially the industrial version of medical ultrasound, but require a very different approach. In contrast to medical activities, industrial applications typically require a correctly angled beam, with large quantities of data, on variable component geometry, and the ability to save and image defects. All this capability is now packaged in a portable unit, which can be used for rapid and reliable weld inspections. Specifically, the OmniScan MX can now perform a single linear scan of the weld, while the instrumentation performs multiple scans at different angles simultaneously. In addition, phased arrays can perform unique scans, like S-scans (sectorial scans), record and display all data in “top, side, end” views or similar, and perform multi-mode scans. Phased arrays permit electronic rastering in many different modes, which saves considerable inspection time; for example, some estimates show that phased arrays are five or more times quicker than manual scanning. Besides being portable and requiring just a single operator, portable phased arrays are now economically competitive with other weld inspection techniques — and generally provide a much better inspection. The “new” techniques consist of forward and backward diffraction for sizing defects. In reality, both these techniques have been around for years, but new technology has made them more practical. Forward diffraction (TOFD or Time-Of-Flight Diffraction) is now well established, and has been demonstrated for many applications. For most weld inspections, TOFD just requires a single linear pass, with two transducers (or arrays) on either side of the weld. TOFD provides good sizing and defect detection in the midwall, though it has dead zones at the two surfaces. Generally, sizing with TOFD is significantly better than with amplitude techniques, but is limited to defects ∼3 mm and up. TOFD also has the great advantage that it is highly independent of defect orientation, unlike pulse echo techniques. Even better, phased arrays can perform both pulse echo and TOFD simultaneously during a single linear scan, so giving essentially a “complete” weld inspection. Another diffraction sizing technique which has received relatively little attention until recently is “tip back diffraction”. This approach uses the low amplitude signals reflected back from crack tips to size defects. Back diffraction has the great advantages that it is intuitive, and can size defects as small as ∼1 mm, which is generally better than TOFD. However, tip back diffraction has the major disadvantage that it is sometimes difficult to correctly distinguish the crack tips from other signals, and signal-to-noise ratio is usually poor. These two limitations are largely overcome by phased arrays; first, the imaging allows correct determination of the crack tip, and second, new piezo-composite arrays with focusing and filtering give significantly improved signal amplitudes. S-scan imaging can be performed with off-the-shelf phased array equipment. Some of the more advanced phased array techniques include: 2D and 1.5D arrays for improved beam shaping and focusing; curved arrays, also for better sizing; special TRL-PA (Transmit-Receive Longitudinal Wave-Phased Array) probes for austenitic steels; additional beams for special inspections. Examples of these inspections on welds will be given. Overall, a combination of phased arrays with TOFD or back diffraction allows the operator to perform cost-effective inspections with high reliability, repeatability, good defect sizing and full data storage.