An Investigation of Viscosity, Relaxation Time, Tilt Angle and Radiation Force Variations by Using a Laser Interferometer Method of a Laser Dye Solvent

SummaryConventional force-balances, “accelerometer balances” and photographic monitoring of freely-flying models are not suitable for use in the Q.M.C. shock tunnel where the force levels are of order 10N for flow durations of about 1 ms. An interferometric method has therefore been developed for following the trajectory of a weakly-restrained model. The prototype system consists of two simple Michelson interferometers, a single He-Ne laser being employed to provide two measurement and two reference beams so that the motion of two points on the model can be followed. The measurement beams are returned by corner-cube retroreflectors carried on the model which ensures that for each measurement arm the reference and measurement beams recombine at the surface of a photo-detector. As the model moves, interference fringes are produced at the detectors, the cycle dark-light-dark corresponding to a model displacement along the measurement beam of ½λ, about 0.3μm. The frequency-modulated wave-trains produced are recorded using two transient recorders, the data being subsequently played back to a two-channel pen recorder giving a record 500 mm in length corresponding to the test time. The fringe number as a function of time is read manually, and the data analysed by curve fitting to a parabola which yields the accelerations of the measurement points. A knowledge of the inertial characteristics of the model then gives the forces on it. By suitably aligning the beams, lift and pitching moment for a ridge-delta of aspect-ratio 1 were obtained. Two models of the same geometric size but of different inertia were tested. All the data were obtained for model displacements less than 1 mm and pitch rotations less than 0.1°.

Download Full-text

Stage Equipped with Single Actuator for Nano-Positioning in Large Travel Range

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.364-366.768 ◽

2007 ◽

Vol 364-366 ◽

pp. 768-772

Author(s):

Yung Cheng Wang ◽

Chiun Jie Lin ◽

Chao Jung Chen ◽

Huay Chung Liou

Keyword(s):

High Precision ◽

Tilt Angle ◽

Laser Interferometer ◽

Low Cost ◽

Positioning System ◽

Precision Positioning ◽

Angle Sensor ◽

Positioning Control ◽

Increasing Demand ◽

Displacement Measurements

Precision positioning is an essential basis for precision mechanical engineering, such as positioning for precision manufacture, or positioning control of robot arms. Due to the increasing demand for precision in the submicrometer range, precision positioning plays an important role for precision manufacture. In this investigation a nano-positioning stage is developed. With the positioning system, high precision positioning and large displacement range can be achieved simultaneously. Advantages of this developed system are positioning driver with single actuator, uncomplicated mechanical structure, low cost and lower hardware requirement. A laser interferometer is used for displacement measurements of the translation stage, and a mini-autocollimator serves as angle sensor for tilt angle measurements. The tilt angle can be minimized with piezo translators and control operations. By the displacement measurements of laser interferometer, the feedback control is performed for positioning in large travel range. High precision positioning in nanometer-order can be achieved with the positioning system. With this development, individual sensor modules are self-accomplished and dominating technologies for the complete nano-positioning system are established.

Download Full-text

The dislocation structure of a 10° [110] tilt boundary in silicon

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100074446 ◽

1983 ◽

Vol 41 ◽

pp. 114-115

Author(s):

B. Cunningham ◽

D.G. Ast

Keyword(s):

Dislocation Structure ◽

Tilt Angle ◽

Imaging Technique ◽

Diamond Lattice ◽

Tilt Boundary ◽

Formation Mechanisms ◽

Diffraction Contrast ◽

Lattice Fringe ◽

Tilt Boundaries ◽

Chemically Vapor Deposited

There have Been a number of studies of low-angle, θ < 4°, [10] tilt boundaries in the diamond lattice. Dislocations with Burgers vectors a/2<110>, a/2<112>, a<111> and a<001> have been reported in melt-grown bicrystals of germanium, and dislocations with Burgers vectors a<001> and a/2<112> have been reported in hot-pressed bicrystals of silicon. Most of the dislocations were found to be dissociated, the dissociation widths being dependent on the tilt angle. Possible dissociation schemes and formation mechanisms for the a<001> and a<111> dislocations from the interaction of lattice dislocations have recently been given.The present study reports on the dislocation structure of a 10° [10] tilt boundary in chemically vapor deposited silicon. The dislocations in the boundary were spaced about 1-3nm apart, making them difficult to resolve by conventional diffraction contrast techniques. The dislocation structure was therefore studied by the lattice-fringe imaging technique.

Download Full-text

A High Angle, Double Tilting Cold Stage for the AEI EM7

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100052262 ◽

1974 ◽

Vol 32 ◽

pp. 450-451

Author(s):

P.R. Swann ◽

A.E. Lloyd

Keyword(s):

Habit Plane ◽

Temperature Control ◽

Tilt Angle ◽

Cooling System ◽

Thermal Drift ◽

High Angle ◽

Cold Stage ◽

High Degree ◽

Better Than

Figure 1 shows the design of a specimen stage used for the in situ observation of phase transformations in the temperature range between ambient and −160°C. The design has the following features a high degree of specimen stability during tilting linear tilt actuation about two orthogonal axes for accurate control of tilt angle read-out high angle tilt range for stereo work and habit plane determination simple, robust construction temperature control of better than ±0.5°C minimum thermal drift and transmission of vibration from the cooling system.

Download Full-text

The use of a Bent Grid to Improve the take-Off Angle for Electron Probe Analysis

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100091780 ◽

1976 ◽

Vol 34 ◽

pp. 360-361

Author(s):

Delbert E. Philpott ◽

David Leaffer

Keyword(s):

Quantitative Analysis ◽

Tilt Angle ◽

Count Rate ◽

Electron Probe ◽

Open Area ◽

Electron Probe Analysis ◽

Background Ratio ◽

Probe Analysis

There are certain advantages for electron probe analysis if the sample can be tilted directly towards the detector. The count rate is higher, it optimizes the geometry since only one angle need be taken into account for quantitative analysis and the signal to background ratio is improved. The need for less tilt angle may be an advantage because the grid bars are not moved quite as close to each other, leaving a little more open area for observation. Our present detector (EDAX) and microscope (Philips 300) combination precludes moving the detector behind the microscope where it would point directly at the grid. Therefore, the angle of the specimen was changed in order to optimize the geometry between the specimen and the detector.

Download Full-text

Methods for three-dimensional reconstruction of cellular components within a thick section

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100141871 ◽

1986 ◽

Vol 44 ◽

pp. 18-21

Author(s):

J. Frank ◽

B. F. McEwen ◽

M. Radermacher ◽

C. L. Rieder

Keyword(s):

Tilt Angle ◽

Tomographic Reconstruction ◽

3D Structure ◽

Three Dimensional ◽

Thick Section ◽

Three Dimensional Reconstruction ◽

Axis Ratio ◽

Dimensional Reconstruction ◽

Cellular Components

The tomographic reconstruction from multiple projections of cellular components, within a thick section, offers a way of visualizing and quantifying their three-dimensional (3D) structure. However, asymmetric objects require as many views from the widest tilt range as possible; otherwise the reconstruction may be uninterpretable. Even if not for geometric obstructions, the increasing pathway of electrons, as the tilt angle is increased, poses the ultimate upper limitation to the projection range. With the maximum tilt angle being fixed, the only way to improve the faithfulness of the reconstruction is by changing the mode of the tilting from single-axis to conical; a point within the object projected with a tilt angle of 60° and a full 360° azimuthal range is then reconstructed as a slightly elliptic (axis ratio 1.2 : 1) sphere.

Download Full-text

Rationale Abklärung von Lebererkrankungen

Therapeutische Umschau ◽

10.1024/0040-5930/a000889 ◽

2017 ◽

Vol 74 (3) ◽

pp. 79-86

Author(s):

Leona von Köckritz ◽

Andrea De Gottardi

Keyword(s):

Acoustic Radiation ◽

Radiation Force ◽

Acoustic Radiation Force ◽

Acoustic Radiation Force Impulse ◽

Alkalische Phosphatase ◽

Gamma Glutamyltransferase ◽

Alpha 1 Antitrypsin

Zusammenfassung. Im klinischen Alltag werden häufig erhöhte Leberwerte beobachtet. In der Regel erfordern sie weitere Abklärungen bezüglich der möglichen Ätiologie und des Schweregrad einer akuten oder chronischen Lebererkrankung. Die Abklärung sollte dabei neben einer gezielten Anamnese und sorgfältigen klinischen Untersuchung, auch die Bestimmung von laborchemischen Markern für Cholestase und Leberfunktionsstörungen (wie Alkalische Phosphatase, gamma-Glutamyltransferase, Bilirubin, Albumin und Gerinnungsfaktoren) umfassen. Die Bestimmung weiterer Parameter wie Ferritin und Transferrinsättigung, Autoimmunantikörper, Virusserologien, alpha-1 Antitrypsin und Coerulolasmin können weitere Hinweise für die kausalen Zusammenhänge der Leberfunktionsstörung liefern. Bei Patienten mit Lebererkrankungen ist eine sonografische Beurteilung der Leber obligat. Ergänzend zur Sonografie werden heute weitere nicht-invasive Methoden wie Fibroscan, Acoustic Radiation Force Impulse Elastometrie und Magnet-Resonanz-Elastografie zur Beurteilung der Leberfibrose eingesetzt. In ausgewählten Fällen ist eine Leberbiopsie notwendig, um den Grad der Fibrose und die Ätiologie der Lebererkrankung zu eruieren. Mithilfe eines Fallbeispiels, diskutieren die Autoren im Folgenden die rationale Anwendung diagnostischer Tests und deren korrekte Interpretation und schlagen eine Orientierungshilfe zur rationalen Abklärung von Patienten mit Lebererkrankungen vor.

Download Full-text

Neue Horizonte bei der Lebersonographie

Praxis ◽

10.1024/1661-8157/a001112 ◽

2012 ◽

Vol 101 (18) ◽

pp. 1161-1166

Author(s):

Hagara ◽

Schwarzenbach ◽

Cerny

Keyword(s):

Acoustic Radiation ◽

Radiation Force ◽

Acoustic Radiation Force ◽

Acoustic Radiation Force Impulse

Dank technologischer Verbesserungen und einer immer besser werdenden klinischen Evidenzlage wird der diagnostische Ultraschall im Vergleich zu den Röntgen- und Magnetresonanzverfahren vermehrt eingesetzt. Dies nicht nur aus Kostengründen, sondern auch um der Zunahme der Strahlenbelastung der Bevölkerung durch diagnostische ionisierende Strahlen entgegenzuwirken. In der folgenden Übersichtsarbeit versuchen die Autoren die neuesten Entwicklungen im Bereich des Leberultraschalls vorzustellen. Bemerkenswert sind Verfahren, die eine dynamische Untersuchung der Leberdurchblutung mittels Kontrastmittelultraschall (Schwefelhexafluorid SonoVue®) und damit Verbesserungen bei der Charakterisierung von fokalen Leberläsionen wie Metastasen extrahepatischer Tumoren, Regeneratsknoten bei Leberzirrhose, fokaler nodulärer Hyperplasie, hepatozellu-lärem Karzinom, Leberhämangiom, Leberadenom sowie fokaler Mehr- oder Minderverfettung ermöglichen. Ebenfalls wichtig sind Techniken, die eine Bestimmung der Gewebekonsistenz mittels transienter Elastographie (Fibroscan), ARFI (Acoustic Radiation Force Impulse) oder Echtzeit-Gewebe-Elastographie erlauben. Die Quantifizierung des Steatosegrads ist für Diagnose und Verlaufsbeurteilung von Leberpathologien unabdingbar.

Download Full-text