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Results for “ASPECT RATIO”
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Fabrication of extreemly high aspect ratio diffraction gratings for X-ray phase contrast imaging.
Abstract not provided.
Copper Electrodeposition in High Aspect Ratio Mesoscale Through-Silicon Vias: Scaling from Die Level to Wafer Level Plating.
Abstract not provided.
AUTOMATED DRILLING OF HIGH ASPECT RATIO SMALL DIAMETER HOLES IN REMOTE CONFINED SPACES.
Abstract not provided.
Cu ECD in High Aspect Ratio Mesoscale TSVs: Scaling from Die Level to Wafer Level Plating.
Abstract not provided.
Direct synthesis of high-aspect ratio zeolite nanosheets
An example material includes a planar layer of MFI zeolite. The planar layer has a thickness in a range between 4 nm and 10 nm for at least 70% of a basal area of the planar layer. In one embodiment, the planar layer includes an embedded particle of an MFI zeolite.
High Aspect Ratio Al-Rich AlGaN Etching Technology for FinFET Fabrication
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A widefield fluorescence microscope with a linear image sensor for image cytometry of biospecimens: Considerations for image quality optimization
Linear image sensors have been widely used in numerous research and industry applications to provide continuous imaging of moving objects. Here, we present a widefield fluorescence microscope with a linear image sensor used to image translating objects for image cytometry. First, a calibration curve was characterized for a custom microfluidic chamber over a span of volumetric pump rates. Image data were also acquired using 15 μm fluorescent polystyrene spheres on a slide with a motorized translation stage in order to match linear translation speed with line exposure periods to preserve the image aspect ratio. Aspect ratios were then calculated after imaging to ensure quality control of image data. Fluorescent beads were imaged in suspension flowing through the microfluidics chamber being pumped by a mechanical syringe pump at 16 μl min{sup −1} with a line exposure period of 150 μs. The line period was selected to acquire images of fluorescent beads with a 40 dB signal-to-background ratio. A motorized translation stage was then used to transport conventional glass slides of stained cellular biospecimens. Whole blood collected from healthy volunteers was stained with 0.02% (w/v) proflavine hemisulfate was imaged to highlight leukocyte morphology with a 1.56 mm × 1.28 mm field of view (1540 ms total acquisition time). Oral squamous cells were also collected from healthy volunteers and stained with 0.01% (w/v) proflavine hemisulfate to demonstrate quantifiable subcellular features and an average nuclear to cytoplasmic ratio of 0.03 (n = 75), with a resolution of 0.31 μm pixels{sup −1}.
Drag of wings with end plates
In this report a formula for calculating the induced drag of multiplanes with end plates is derived. The frictional drag of the end plates are used, is sufficiently large to increase the efficiency of the wing. Curves showing the reduction of drag for monoplanes and biplanes are constructed; the influence of gap-chord ratio, aspect ratio, and height of end plate are determined for typical cases. The method of obtaining the reduction of drag for a multiplane is described. Comparisons are made of calculated and experimental results obtained in wind tunnel tests with airfoils of various aspect ratios and end plates of various sizes. The agreement between calculated and experimental results is good. Analysis of the experimental results shows that the shape and section of the end plates are important.
Supersonic Wave Drag of Sweptback Tapered Wings at Zero Lift
On the basis of a recently developed theory for sweptback wings at supersonic velocities, equations are derived for the wave drag of sweptback tapered wings with thin symmetrical double-wedge sections at zero lift. Calculations of section wave-drag distributions and wing wave drag are presented for families of tapered plan forms. Distributions of section wave drag along the span of tapered wings are, in general, very similar in shape to those of untapered plan forms. For a given taper ratio and aspect ratio, an appreciable reduction in wing wave-drag coefficient with increased sweepback is noted for the entire range of Mach number considered. For a given sweep and taper ratio, higher aspect ratios reduce the wing wave-drag coefficient at substantially subcritical supersonic Mach numbers. At Mach numbers approaching the critical value, that is, a value equal to the secant of the sweepback angle, the plan forms of low aspect ratio have lower drag coefficients. Calculations for wings of equal root bending stress (and hence different aspect ratio) indicate that tapering the wing reduces the wing wave-drag coefficient at Mach numbers considerably less than the critical value but increases the drag coefficient at Mach numbers near the critical values. Comparisons on the basis of constant aspect ratio, however, indicate an increase of the wing wave-drag coefficient with taper at Mach numbers considerably less than the critical value and a decrease of the drag coefficient with taper at Mach numbers near the critical value.
Supersonic Wave Drag of Sweptback Tapered Wings at Zero Lift
On the basis of a recently developed theory for sweptback wings at supersonic velocities, equations are derived for the wave drag of sweptback tapered wings with thin symmetrical double-wedge sections at zero lift. Calculations of section wave-drag distributions and wing wave drag are presented for families of tapered plan forms. Distributions of section wave drag along the span of tapered wings are, in general, very similar in shape to those of untapered plan forms. For a given taper ratio and aspect ratio, an appreciable reduction in wing wave-drag coefficient with increased sweepback is noted for the entire range of Mach number considered. For a given sweep and taper ratio, higher aspect ratios reduce the wing wave-drag coefficient at substantially subcritical supersonic Mach numbers. At Mach numbers approaching the critical value, that is, a value equal to the secant of the sweepback angle, the plan forms of low aspect ratio have lower drag coefficients. Calculations for wings of equal root bending stress (and hence different aspect ratio) indicate that tapering the wing reduces the wing wave-drag coefficient at Mach numbers considerably less than the critical value and a decrease of the drag coefficient with taper at Mach numbers near the critical value.
Unsteady Subsonic and Transonic Potential Flow over Helicopter Rotor Blades
Differential equations and boundary conditions for a rotor blade in forward flight, with subsonic or transonic tip Mach number, are derived. A variety of limiting flow regimes determined by different limits involving blade thickness ratio, aspect ratio, advance ratio and maximum tip Mach number is discussed. The transonic problem is discussed in some detail, and in particular the conditions that make this problem quasi-steady or essentially unsteady are determined. Asymptotic forms of equations and boundary conditions that are valid in an appropriately scaled region of the tip and an azimuthal sector on the advancing side are derived. The equations are then put in a form that is valid from the blade tip inboard through the strip theory region.
An investigation of corner separation within a thrust augmenter having Coanda jets
The development of separation in corners of thrust augmentor wings having Coanda jets was investigated using hot film surface sensors and pressure transducers. Separation on the test augmentor began at a corner very close to the augmentor exit and then rapidly proceeded upstream. Measurements of the pressure fields in the corner region indicated that a modified form of the Stratford criterion could be used to predict the onset of separation. Testing was conducted over a range of nozzle pressure ratios, aspect ratios, diffuser angles, and designs of the boundary layer and Coanda nozzles.
Data and analysis procedures for improved aerial applications mission performance
An analysis procedure is given and cases analyzed for the effects of wing geometry on lateral transport of a variety of agricultural particles released in the wake of an agricultural airplane. The cases analyzed simulate the release of particles from a fuselage centerline-mounted dry material spreader; however, the procedure applies to particles released anywhere along the wing span. Consideration is given to the effects of taper ratio, aspect ratio, wing loading, and deflected flaps. It is noted that significant lateral transport of large particles can be achieved using high-lift devices positioned to create a strong vortex near the location of particle release.
Analysis of fully stalled compressor
An analysis yields a model for energy transfer in compressor stages operating in the closed-throttle condition. The derivation indicates that three geometry parameters (hub/tip ratio, aspect ratio, and rotor blade setting angle) influence the values of pressure coefficient when the compressor flow is close to zero.
A Conceptual Wing Flutter Analysis Tool for Systems Analysis and Parametric Design Study
An interactive computer program was developed for wing flutter analysis in the conceptual design stage. The objective was to estimate flutt er instability boundaries of a typical wing, when detailed structural and aerodynamic data are not available. Effects of change in key flu tter parameters can also be estimated in order to guide the conceptual design. This userfriendly software was developed using MathCad and M atlab codes. The analysis method was based on non-dimensional paramet ric plots of two primary flutter parameters, namely Regier number and Flutter number, with normalization factors based on wing torsion stiffness, sweep, mass ratio, taper ratio, aspect ratio, center of gravit y location and pitch-inertia radius of gyration. These parametric plo ts were compiled in a Chance-Vought Corporation report from database of past experiments and wind tunnel test results. An example was prese nted for conceptual flutter analysis of outer-wing of a Blended-Wing- Body aircraft.
A Theoretical Investigation of Vortex-Sheet Deformation Behind a Highly Loaded Wing and Its Effect on Lift
The induced drag polar is developed for wt-ngs capable of attaining extremely high loadings while possessing an elliptical distribution of circulation. This development is accomplished through a theoretical investigation of the vortex-wake deformation process and the deduction of the airfoil forces from the impulse and kinetic energy contents of the ultimate wake form. The investigation shows that the induced velocities of the wake limit the maximum lift coefficient to a value of 1.94 times the wing aspect ratio, for aspect ratios equal to or less than 6.5, and that the section properties of the airfoil limit the lift coefficient to 12.6 for aspect ratios greater than 6.5. Relations are developed for the rate of deformation of the vortex wake. It is also shown that linear wing theory is app1icable up to lift coefficients equal to 1.1 times the aspect ratio.
Cost-Benefit Analysis of High-Strength Materials for Safety-Related Nuclear Reinforced Concrete Shear Walls
A numerical parametric investigation was conducted to determine the economic benefits of utilizing high-strength concrete and high-strength steel reinforcing bar (rebar) in reinforced concrete (RC) shear walls for nuclear power plant structures. Thick RC shear walls with low height-to-length aspect ratios (i.e., aspect ratios, h{sub w}/l{sub w}≤2.0, where h{sub w} is the wall height and l{sub w} is the wall length) are the most common lateral load resisting members in non-containment, safety-related nuclear structures. Typically, the walls are reinforced with multiple layers of overlapping, large-diameter vertical and horizontal rebar on each face. These heavily-reinforced walls provide large lateral stiffness and strength to prevent significant deformations and/or cracking that could compromise the integrity of the nuclear facility. However, this design adversely affects constructability as the rebar cages become highly congested. The time, labor, and materials required for this construction lead to high overall project costs. There has been a recent research thrust in the U.S. to allow high-strength rebar in non-nuclear building structures. While some of this research (e.g., steel properties, bond, anchorage) is applicable to RC structures in general, there are important differences specific to nuclear structures, such as much thicker walls (often controlled by radiation and thermal cycling), larger reinforcement ratios, and increased susceptibility to shear-controlled behavior (due to low aspect ratios). An important limiting factor for non-nuclear structures in seismic regions is the reduced deformation capacity of high-strength rebar as compared with normal-strength rebar used in current practice. Differences in seismic design philosophy lessen this limitation for nuclear structures (i.e., nuclear structures are designed more conservatively and allowed to undergo significantly smaller nonlinear displacements), making high-strength rebar a promising alternative to reinforcement currently permissible in the ACI 349-13 code requirements, which govern the design of nuclear safety-related concrete structures. To improve constructability and economy, this study investigates the benefits of using high-strength rebar [i.e., ASTM A615 Grade 550 (U.S. Grade 80); ASTM A1035 Grades 690 and 830 (U.S. Grades 100 and 120), where the grade indicates the specified yield strength of the steel in MPa (ksi)] together with high-strength concrete [compression strengths up to 138 MPa (20.0 ksi)] in RC nuclear shear walls. These strength ranges represent steel and concrete materials that are commercially available in the U.S. High-strength rebar can significantly reduce the required steel areas, thereby reducing material/fabrication costs, reducing rebar congestion (fewer/smaller bars and bar layers), and facilitating concrete consolidation and placement. Previous research on the use of high-strength rebar and/or high-strength concrete in nuclear RC structures does not exist in North America. A recent study assessed the potential of high-strength steel to reduce the rebar volume in non-nuclear building construction. In Japan, researchers investigated the use of high-strength materials in safety-related nuclear RC structures, but did not explore the economic benefits of these materials. To address this knowledge gap, the current paper describes a numerical parametric investigation on the potential cost savings of nuclear shear walls with high-strength rebar and/or concrete through comparisons against state-of-practice walls with normal-strength materials. Overall, the results demonstrate that significant economic benefits can be realized by implementing high-strength rebar and concrete in these structures. (authors)