The Experts below are selected from a list of 2274 Experts worldwide ranked by ideXlab platform
Graham Sattler - One of the best experts on this subject based on the ideXlab platform.
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Hands-Free Transcranial Color Doppler Probe
2012Co-Authors: Robert C. Chin, Srihdar Madala, Graham SattlerAbstract:Current transcranial color Doppler (TCD) transducer probes are bulky and difficult to move in tiny increments to search and optimize TCD signals. This invention provides miniature motions of a TCD transducer probe to optimize TCD signals. The mechanical probe uses a spherical beaRing in guiding and locating the tilting crystal face. The lateral motion of the crystal face as it tilts across the full range of motion was achieved by minimizing the distance between the pivot location and the crystal face. The smallest commonly available metal spherical beaRing was used with an outer diameter of 12 mm, a 3-mm tall Retaining Ring, and 5-mm overall height. Small geared motors were used that would provide sufficient power in a very compact package. After confirming the validity of the basic positioning concept, optimization design loops were completed to yield the final design. A parallel motor configuration was used to minimize the amount of space wasted inside the probe case while minimizing the overall case dimensions. The distance from the front edge of the crystal to the edge of the case was also minimized to allow positioning of the probe very close to the ear on the temporal lobe. The mechanical probe is able to achieve a +/-20deg tip and tilt with smooth repeatable action in a very compact package. The enclosed probe is about 7 cm long, 4 cm wide, and 1.8 cm tall. The device is compact, hands-free, and can be adjusted via an innovative touchscreen. Positioning of the probe to the head is performed via conventional transducer gels and pillows. This device is amendable to having advanced software, which could intelligently focus and optimize the TCD signal.
Madala Srihdar - One of the best experts on this subject based on the ideXlab platform.
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Hands-Free Transcranial Color Doppler Probe
2012Co-Authors: Sattler Graham, Chin Robert, Madala SrihdarAbstract:Current transcranial color Doppler (TCD) transducer probes are bulky and difficult to move in tiny increments to search and optimize TCD signals. This invention provides miniature motions of a TCD transducer probe to optimize TCD signals. The mechanical probe uses spherical beaRing in guiding and locating the tilting crystal face. The lateral motion of the crystal face as it tilts across the full range of motion was achieved by minimizing the distance between the pivot location and the crystal face. The smallest commonly available metal spherical beaRing was used with an outer diameter of 12 mm, a 3-mm tall Retaining Ring, and 5-mm overall height. Small geared motors were used that would provide sufficient power in a very compact package. After confirming the validity of the basic positioning concept, optimization design loops were completed to yield the final design
Iwao Ikai - One of the best experts on this subject based on the ideXlab platform.
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double purse stRing telescoped pancreaticogastro stomy using an atraumatic self Retaining Ring retractor in a subtotal stomach preserving pancreaticoduodenectomy
Annals of Surgical Oncology, 2016Co-Authors: Masato Narita, Ryo Matsusue, Hiroaki Hata, Takashi Yamaguchi, Tetsushi Otani, Iwao IkaiAbstract:Background Pancreatoenteric anastomotic failure is the main cause of pancreatic fistula after pancreaticoduodenectomy (PD). Double purse-stRing telescoped pancreaticogastrostomy, reported by Addeo et al., is an easy and safe procedure.1 The aim of this article was to introduce our technique of pancreaticogastrostomy using an atraumatic self-Retaining Ring retractor (Alexis Wound Retractor®) in a patient undergoing subtotal stomach-preserving PD (SSPPD).
Vazquez Bengochea Leticia - One of the best experts on this subject based on the ideXlab platform.
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Slurry Assay and Flow Characterization in Chemical Mechanical Planarization
The University of Arizona., 2018Co-Authors: Vazquez Bengochea LeticiaAbstract:This thesis includes three studies which, even if independent of one another, have the same underlying goal: optimization of slurry use in chemical mechanical planarization (CMP). Slurry is one of the major concerns in CMP, both for economical and environmental reasons. On the one hand, it represents more than 50% of the cost of ownership of the process, which translates into more than $1 billion per year. On the other hand, it makes waste management very complicated and costly, since it contains nanoparticles and chemicals that are highly hazardous and traditional wastewater treatment is not effective. Therefore, the studies presented in Chapters 4 to 6 aim to optimize slurry distribution on the pad and slurry in-situ monitoRing to optimize its use and reduce its consumption. In the first study, a method to visualize and quantify the slurry bow wave that forms at the leading edge of the Retaining Ring duRing polishing is developed. This technology relies on high-speed videography and image analysis, and it overcomes many limitations of other slurry visualization methods. Previous work was performed using UV light, so it needed a dark environment and black pads and it suffered from photobleaching. Our technique avoids all those problems: it can be used with common industrial equipment in normally lit environment and it provides real-time data, with a data acquisition speed of 240 frames per second. We apply our method to polishing experiments with different flow rates and we are able to quantify the slurry bow wave width. Two different regions on the pad are analyzed, one closer to the center and another one closer to the edge. The bow wave width in the region closer to the edge is not significantly affected by changes in flow rate. We believe that in this region most of the slurry has already been transported through the slots or to the waste stream, so the bow wave is governed by a hydrodynamic boundary layer on the Retaining Ring wall, which remains approximately constant. However, in the region closer to the center, the bow wave is formed due to the excess slurry availability in this region, and its width changes under different conditions. After obtaining the spectral fingerprint, we can successfully attribute the bow wave fluctuations to kinematics of the system. The second study is a continuation of the previous one, where we employ the new method we have developed to analyze the differences in bow wave (i.e., in slurry distribution) under different polishing conditions and with different consumables. As such, we perform experiments with different Retaining Ring slot designs, conditioning disc designs and conditioning modes (i.e., in-situ vs. ex-situ). A Retaining Ring with rounded slots results in wider bow wave than a Ring with sharp slots. When in-situ conditioning is employed, four peaks corresponding to the conditioner sweeping frequency are observed, which are not present using ex-situ conditioning. A conditioner disc with vanes on its surface results in a thinner bow wave than a full-faced conditioner disc. We are able to explain all those variations based on the slurry availability and flow dynamics in each case. As in the previous study, we also obtain the spectral fingerprint to elucidate the root causes of the observed bow wave fluctuations. The third study focuses on slurry monitoRing and it investigates the possibility of introducing refractive index (RI) measurements to obtain a better control on slurry density and composition. Slurry storage, handling and blending often introduce changes in composition and can lead to density non-uniformity, which can impact CMP performance. Commonly employed densitometers are often not precise enough to detect those changes and can potentially introduce contamination in the slurry due to metal corrosion. We study three industrially employed silica-based slurries and find a very strong linear correlation between density and refractive index, with regression coefficients in the excess of 0.95. When we compare the approximate limit of detection of both instruments, the refractometer can detect changes in slurry concentration that are up to 50% smaller than the densitometer. The introduction of RI measurements to monitor slurry properties could lead to an earlier detection of slurry changes in composition and improved performance. Overall, the work included in this thesis contributes to the effort my research group has been doing to develop methods and consumables that reduce COO and EHS impact in CMP, focusing this time on the concerns derived from slurry use
A Q Khan - One of the best experts on this subject based on the ideXlab platform.
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study of inclusions in a failed aero engine component
Metallurgical and Materials Transactions A-physical Metallurgy and Materials Science, 1997Co-Authors: A Tauqir, I Salam, F H Hashmi, A Q KhanAbstract:The cause of the fatigue failure in the Retaining Ring of the compressor region of an aero-engine turbine was found to be the presence of a high concentration of nonmetallic inclusions. The results of chemical analysis were used to estimate the phases present. The most frequently observed inclusions were spinel solid solutions of the type MO · N2O3, where M=Fe, Mn, or Mg and N=Cr or Al. The detrimental inclusions were corundum, calcium aluminates, cristobalite, and silicates. The most detrimental phases were traced on the surfaces of the specimens fractured using impact loading; the comparison is being made with the polished surfaces and the tensile specimen fracture surfaces. The inclusions in the failed Retaining Ring were compared with the ones in a similar component obtained from a used engine. In the case of the latter, a large number of fine and elongated (Mn, Cr, Fe)S inclusions were present along with spinels. The nondeformable, rigid oxide particles are considered more undesirable than the sulfides as far as fatigue life of the component is concerned. It has been reported that the presence of sulfides may eliminate the stresses due to oxides.
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Causes of fatigue failure in an aero-engine component
Engineering Failure Analysis, 1997Co-Authors: I Salam, A Tauqir, A Q KhanAbstract:Abstract The Retaining Ring of an aero-engine failed in fatigue mode. Metallurgical investigations revealed that there was a high density of inclusions in the material which are not deformable. DuRing deformation, they disintegrated and formed voids which could act as sharp notches duRing fatigue loading. Axial surface cracks were visible on the surface of the Ring. It is proposed, as found in previous failure analysis studies, that surface cracks trap lubricants used duRing the drawing process of the wires, and carburize the region duRing subsequent annealing. These regions can also be potential sites of fatigue crack initiation.