Symmetric Angle Research Articles

Individual Phase Control of a Static Compensator for Load Compensation and Voltage Balancing and Regulation

The purpose of this paper is to discuss the developments in control strategies for static compensators using programmable high speed digital controllers. Individual phase control of static compensators has been used in the past for balancing and power factor correction of arc furnace and single phase railway loads. With the advancements in programmable high speed controllers based on microprocessor technology, more complex computations can be accurately performed for the additional purpose of regulating and balancing the voltage feeding such loads. Other developments that will be discussed are the use of symmetrical firing angle control to eliminate the even harmonics in the current spectrum and hence, reduce the cost of filtering, and the synchronization of the controller to the phase-locked-loop firing circuit to compensate for frequency variations. The results of simulator studies will be presented.

Mastery of the pass system for a symmetrical bulb angle

Mastery of the pass system for a symmetrical bulb angle

The new laval facility for polarization measurements

Abstract A new polarimetry facility has been set up. The four polarimeters used in different geometries are equipped with silicon or carbon analyzers. Extreme care has been taken to cancel out false asymmetries from apparatus misalignments. To that purpose, an automatic beam centering system has been built, two polarimeters are always run simultaneously on both sides of the beam at symmetric angles and geometric means are performed on data reduction. The installation is described in detail and data analysis and calibration runs are presented and discussed.

A simplified guide to trimming esthetically appealing diagnostic casts

T he production of consistently esthetically appealing and useful casts can become routine procedure by developing a systematic trimming technique. In addition to being useful as effective visual aids during cast presentations and patient education diagnostic casts are also valuable as showcase models of successful rehabilitations.’ The plaster cast of the entire dentition trimmed to symmetrical lines and angles has a value in direct proportion to the skill used in its production. The dentist or hygienist who uses artistically trimmed diagnostic casts will be likely to demonstrate similar skills in treating their patients. In addition, from a medicolegal aspect accurate diagnostic casts are accepted as records of results accomplished and thereby provide some protection for the dentist when needed.

Computer simulation of spatial filtering of modes by vertical array steering and double symmetrical angles of sight in shallow water propagation

A method is proposed for angular filtering for a selected normal mode by means of a steered array. Examples are given for spatial filtering by a single angle of sight and by association of the symmetrical angle of sight. Calculations were made for the particular case corresponding to previous experiments. Identity between the spatial filtering by amplitude shading with functions of one of the normal modes and by electronic steering with phase-shifters is demonstrated. Possibilities for modal spectroscopy and adaptive filtering are investigated.

インコネル600粗大柱状晶を用いた水素割れの方位差依存性の研究

The effect of misorientation on the intergranular cracking of cathodically hydrogen-charged specimens under the external tensile stress was investigated on Inconel alloy 600 with coarse columnar crystals. As the deviation of the growing direction from 〈100〉 orientation was within 10°, the grain boundaries were treated as simple tilt boundaries with 〈100〉 rotation axis. Misorientation of a grain boundary is described in terms of the three angles, relative tilt angle (ω), tilt angle (α) and symmetrical tilt angle (θ), determined with {100} planes nearest to the grain boundary plane. The depth of intergranular cracking (D) of the specimens water-quenched and sensitized at 973 K for 7.2 ks changed over a wide range up to 200 μm. There is no clear relation between D and ω. It was found that D increased with decreasing α in classified cases of ω=2°∼10° and ω=40°∼45°, and also with decreasing θ. This result shows that grain boundaries of which the planes are close to {100} of adjacent crystals have higher susceptibility to cracking. Markedly lower susceptibilities of symmetrical coincidence boundaries such as ∑5 and ∑13 are recoganized against the normal relation of D with θ. Shallower transgranular cracks compared with intergranular cracks were always observed along {100} plane. The relationship between misorientation of grain boundaries and carbide precipitation is not clear, expect the fact that symmetrical coincidence boundary and tilt boundary with ω=2°∼10° are carbide-free.

ON RESOLUTION OF RELAXATION MECHANISM IN FIBER-REINFORCED COMPOSITE

In order to elucidate the mechanism of mechanical dispersion in fiber-reinforced composite, temperature dependence of the dynamic viscoelastic properties in simple extention was studied for the epoxy resin composite reinforced with satin woven glass cloth, in which the symmetrical angle between the directions of extension and each fiber axis of warp and woof was adjusted to ±67.5° (COA67.5), ±45° (COA45), and ±22.5° (COA22.5).The composite reinforced with the cloth in which the fiber axis of warp coincided with the direction of extension (COA0), and that reinforced with uniaxially aligned continuous glass fiber to the direction of extension (ROA0) were also used as samples.Although the primary transition is merely observed for COA67.5 and COA45, a sub-transition appears at a temperature above the primary transition for COA22.5 and COA0. The sub-transition for COA0 appears more distinctly separated from the primary transition as compared with the case of COA22.5. E″ and tan δ vs. temperature curves for ROA0 are hardly distinguishable from those for COA0.Our results are similar to those reported by Reed6), in which mechanical dispersion in flexural deformation is studied for the unidirectional epoxy-glass fiber composite at various fiber orientation angles.This implies that the effect of fiber intersection has no serious influence on the mechanical dispersion behaviors. The present and Reed's results can be explained by the mechanism proposed by Lipatov et al.7) that the separation of the sub and primary transitions occurs if the boundary layers formed on the surface of reinforcement and the bulk polymer phase are aligned parallel to the direction of deformation. The sub-transition reported earlier by us for composites reinforced with randomly distributed short glass fiber is also clearly explained by the mechanism proposed by Lipatov et al.

Vanadyl(IV) conalbumin. I. Metal binding site configurations

Electron paramagnetic resonance (epr) and ultraviolet difference spectroscopy of vanadyl conalbumin indicate a binding capacity of two vanadyl ions, VO2+, per protein molecule in the pH 8–11 range; the binding capacity drops in the pH 6–8 range with an apparent pKa′ = 6.6. Iron-saturated conalbumin does not bind vanadyl ions, which suggests common binding sites for iron and vanadium. Ultraviolet difference spectroscopy indicates 2–3 tyrosines are involved in the binding of each metal ion; pH titrations show that three protons are released per vanadyl ion bound by conalbumin. Room and liquid nitrogen temperature X-band (ca. 9.2–9.5 gHz) epr spectra show that the vanadyl ion binds in three magnetically distinct environments (A, B, and C) that arise from interconvertible metal site configurations. These configurations are probably examples of conformational substrates of the protein. Q-band (ca 34 gHz) epr spectra resolve the spectral features more clearly and show that two configurations (A and B) have axially symmetric epr parameters but angles of noncoincidence of 12° and 8°, respectively, between the z components of the g and nuclear hyperfine tensors. The third (C) configuration has rhombic magnetic symmetry and a 6° angle of noncoincidence. These observations demonstrate that the metal sites are of low symmetry and are flexible in their geometry about the metal.The isotropic g and nuclear hyperfine tensor values and the line widths used in computer-simulated epr spectra are consistent with four oxygen or three oxygen and one nitrogen donor atoms binding equatorially to the VO2+ group. The apparent stability constant indicates that vanadyl ion binds to conalbumin approximately twelve orders of magnitude more weakly than iron to human serotransferrin but still sufficiently strongly to overcome hydrolysis.

Grooves on Phobos: Their distribution, morphology and possible origin

A remarkable characteristic of the surface of Phobos is that it is densely covered by grooves—long linear depressions formed in a regolith. Typically, grooves are 100–200 m wide, 10–20 m deep, and have smooth concave‐up cross profiles. Some can be traced for up to 30 km. Groove paths follow the intersection of planes with the surface of Phobos. Groove planes are grouped in four sets of parallel members. All sets are nearly parallel to the intermediate axis of Phobos: one is parallel to the equatorial plane, another perpendicular to the long axis of Phobos, the other two sets make symmetric angles (∼25°) with the equatorial plane. Grooves are widest and deepest near Stickney, the largest crater on Phobos, and are absent from the trailing region of Phobos, roughly opposite to Stickney. Groove formation occurred during a restricted time interval, which, on the basis of superposed craters, closely followed the formation of Stickney. The impact that formed Stickney probably opened fractures along preexisting planes of weakness and caused subsequent formation of the grooves either by drainage of regolith into open fractures or by ejection of regolith overlying the fractures or a combination of both processes. Heating due to the impact may have produced enough steam from the satellite's carbonaceous chondrite material to expell regolith along the fractures. Other proposed mechanisms of groove formation, such as tidal stressing, internal heating, capture fragmentation, etc., cannot account adequately for the pattern, age, and morphology of the grooves. The lack of grooves on Deimos could be explained by the absence on its surface of a crater large enough to have severely fractured the outer satellite.

BRANCH GEOMETRY AND EFFECTIVE LEAF AREA: A STUDY OF TERMINAUA‐BRANCHING PATTERN. 1. THEORETICAL TREES

Single lateral branches and branch tiers of Terminalia catappa L. are simulated and drawn by computer. Leaf clusters on the branches are approximated by discs, and the effective leaf areas are determined by use of Dirichlet domains. Theoretical optimal branching angles which produce the maximum effective leaf area are obtained from simulations. Symmetrical and asymmetrical branching angles are contrasted; the latter characterize real trees. Varying leaf disc radius and ratio of branch‐unit lengths affects optimal branching angles, as does the symmetry of a tier of five branches. Leaf area indices for individual branches and branch tiers are given for all simulations. The number of branches in a tier has a major effect on leaf area index and effective leaf area. The theoretical optimal branching angles of many simulations are very close to the values observed in real trees of T. catappa. We conclude that the observed branching angles and number of branches in a tier of this species optimize light interception within constraints of a fixed pattern of branching, one that is widespread among tropical trees.

Two-spectator quasifree processes

Two-spectator quasifree processes (graphs with two spectator particles) for the 3He( 3He, dd)pp reaction at the symmetric angle pairs θ = 30.1° at E 3He = 50 MeV and θ = 37° at E 3He = 78 MeV are investigated. The theoretical cross sections are calculated with the PWIA model. The measured cross sections are smaller but have shapes which are in good agreement with the calculation. The ratio N = experiment/theory is approximately 0.05 at 50 MeV and 0.1 at 78 MeV. The reaction 2H(d, pp)nn also was studied at the symmetric angle pair θ = 34.8° and E 2H = 34.7 MeV and the ratio is about 0.14.

A study on simultaneous symmetrical motions.

Three right handed male subjects performed a simultaneous symmetical task involving the motions of reach and pressing buttons. Simultaneous performance time was investigated at several symmetical locations. The symmetrical locations were defined by the combinations of different levels of separation distance, angle and distance. Three levels of separation distance (3, 9 and 15 inches), seven levels of angle (0, 15, 30, 45, 60, 75 and 90 degrees from the frontal reference plane) and three levels of distance (6.5, 11.0 and 15.5 inches) were applied to both hands equally. It was found that separation distance, angle and distance were significant factors in simultaneous performance. The performance time was increased when the symmetrical angle region was varied from the 0--45 degrees region to the 45--90 degrees region. Specifically, the performance time was at the minimum at 15 degrees of symmetrical angle and at the maximum at 90 degrees of symmetrical angle. In addition, the performance time increased not only as the distance of the moves was increased, but also as the separation distance interval was increased (i.e., the separation distance interval varied from a 3--9 inch interval to a 9--15 inch interval).

Computer simulation of symmetrical high angle boundaries in aluminium

The internal energy of symmetrical high angle tilt boundaries with an 〈001〉 axis has been calculated using a potential for aluminium. The computer program used permits relaxations involving rigid translations parallel and perpendicular to the boundary as well as individual atom rearrangements, subject to overall conservation of volume. The calculated energy was found to vary by a factor of about two for coincidence boundaries with 5 ⩽ Σ ⩽ 41 but did not depend simply on the size of the boundary period. The condition for low energy configurations appears to require a translation of the adjacent grains away from the coincidence position to a state where characteristic interlocking groups of closely packed atoms occur in the boundaries.

The idealization of scaffold couplers for performance tests and scaffold analysis

A scaffold coupler may be regarded as a short rigid member having multiple elastic connections at both or at one of its ends. The elastic properties need to be determined experimentally; suitable tests are described. Results are used for establishing matrices for unsymmetrical and symmetrical right angle couplers and for symmetrical swivel couplers. An example is given of the use of scaffold coupler matrices in calculations for the elastic instability strength of a three-storey scaffold tower.

Observations of energetic electrons (E≳ 200 keV) in the Earth's magnetotail: Plasma sheet and Fireball observations

With the California Institute of Technology electron/isotope spectrometer (EIS) aboard the earth-orbiting spacecraft Imp 8, intense energetic electron events (E ≳ 200 keV) have been observed at ∼30 R_E in the magnetotail on 13 of 28 magnetotail passes. In one class of events, peak absolute intensities j(E ≳ 200 keV) = 10^³–10^4 el (cm^² s sr)^(−1) are detected; the differential energy spectra for these events are very steep, with power law indices of ∼7. For this class of observations, symmetric electron pitch angle distributions are detected with the presence of little or no unidirectional streaming, a finding consistent with quasi-trapped motion of the particles. Concurrent observations with other instrumentation on the same spacecraft indicate that the local magnetic fields possess northward components while simultaneous plasma (50 eV ≤ E ≤ 45 keV) data show bulk flow speeds of a few hundred kilometers per second or less, with intense plasma heating ordinarily occurring. A second distinct class of events corresponds to lower average absolute electron intensities (E ≳ 200 keV), typically harder electron energy spectra, and strong intermittent field-aligned (and tailward) unidirectional streaming of the energetic electrons. During periods when this class of events is observed in the plasma sheet, strong southward components are found in the local magnetic fields, and large tailward bulk plasma flow has been reported (with tailward jetting in excess of 1000 km s^(−1) in certain cases). The second class of events is consistent with energetic electron motion on essentially open field lines. These streaming events are found to be associated with apparent localized acceleration regions in the magnetotail.

The effect of relative crystal orientation on the liquid metal induced grain boundary fracture of aluminum bicrystals

The effects of relative crystal orientation on liquid metal induced intergranular fracture were studied to: 1) verify the existence of the theoretically and experimentally predicted orientation dependence of this process; and 2) determine which crystallographically related property produced such dependence. A base metal of 99.993 pct pure aluminum and a liquid metal of Hg-3 at. pct Ga were chosen as the embrittlement couple. Bicrystals of aluminum were grown with symmetric tilt boundaries so that: 1) individual boundaries could be tested; and 2) the resulting embrittlement susceptibility of each boundary could be correlated with a controlled crystallographic variable, the tilt angle. A fracture mechanics testing method was developed which enabled the crack propagation resistance of each grain boundary in the Hg-3 at. pct Ga atmosphere to be determined by yielding the crack extension force of a propagating crack. The variation in crack extension force with symmetric tilt angle was analyzed to determine what crystallographically related property produced the observed variations. Consideration of the crystallographically related properties of: 1) slip compatibility between adjacent grains; 2) grain boundary atomic density; and 3) grain boundary energy led to the conclusion that the observed variations were caused by variations in grain boundary energy, and a mathematical relationship was developed that expressed the dependency.

Symmetrical and Extinction Angle Control of Solid-State Series Motor Drive

In this paper, two control schemes are proposed and investigated for solid-state dc series motor drive. Performance characteristics such as torque speed, input harmonic content, power factor variation, and peak motor current are obtained for both control schemes and compared with the commonly used phase-angle control scheme under identical operating conditions. The input power factor is always lagging in the phase and symmetrical angle control schemes, while it is leading in extinction angle control scheme over a wide range of speed and power. Each control scheme appears to have certain merits over the other schemes. Experimental results verify the basic principles of operation and demonstrate the feasibility of these control schemes.

Power spectra observed in laser scattering from moving, polydisperse particle systems in flames—I. Theory

Theoretical expressions are derived for the photocurrent power spectra observed with laser scattering from moving, polydisperse particle systems. The analysis refers to self-beating of scattered radiation (to which we refer as the homodyne spectrum) and beating between the laser beams scattered in the same direction from two, equally-intense incident laser beams which arrive at symmetrical angles with respect to the scattering direction (to which we refer as an example of heterodyne spectroscopy or, more briefly, as the heterodyne spectrum). When we use a spherically-symmetric Gaussian distribution for the illumination intensity in the coherence volume (scattering region), we obtain a Voigt profile for the photocurrent power spectrum in the general case. We have used the theoretical relations derived for moving systems in order to estimate the maximum values of the particle diameters which are measurable for Stokes-Einstein diffusion when radiation is scattered from He-Ne or Ar-ion lasers.

Quasi-free scattering and final state interactions in the reaction 2H(p,2p)n at 585 MeV

The reaction 2H(p,pp)n has been observed in a kinematically complete experiment at 585 MeV. A neutron-proton final state interaction was observed for an angle pair of 41°-61°. The spectral shape agrees reasonably well with the simple final state interaction theory. Quasi-free scattering was observed in the momentum spectrum for symmetric angles of 41°-41°. The spectator neutron momentum ranged from 0 to 425 MeV/ c. The simple impulse approximation using the Hulthén wave function describes the data very well out to 240 MeV/ c, at which point a sudden departure is observed.

The 6Li(p, 2p) 5He reaction at 100 MeV

The 6Li(p, 2p) 5He reaction has been studied at a proton bombarding energy of 100 MeV with good energy and angular resolution for proton separation energies up to 50 MeV. Data were taken for 17 coplanar symmetric angle pairs yielding both energy sharing spectra and coplanar symmetric angular correlations for various regions of separation energy. The data for the 5He ground state ( 3 2 − resonance ) does not show a significant minimum at zero recoil momentum, suggesting a contribution from an s-state knockout leading to this continuum state. DWIA calculations are presented which reproduce most of the important features of the data. These calculations indicate the importance of both the distortion effects and the offenergy-shell effects at this energy.