Split Angle Research Articles

An evaluation of the ergonomics of three computer keyboards

The influence of keyboard design on hand position, typing productivity and keyboard preference was evaluated by comparing two segmented alternative designs with the linear standard keyboard. The FIXED alternative keyboard featured a split angle of 12° and a moderate lateral inclination angle of 10°. The adjustable OPEN alternative keyboard was used with a 15° split setting, which resulted in a marked 42° of demiboard lateral inclination. Sixteen typists, who completed 10 h of training on both alternative keyboards, were videotaped while typing set texts on all three keyboards. Forearm and wrist angles based on threedimensional video analyses were significantly different (p< 0.05) among the three designs tested. Both alternative keyboards placed the forearm and wrist closer to neutral positions than did the standard keyboard. While the OPEN keyboard reduced pronation, it simultaneously increased radial deviation. The FIXED keyboard kept the forearm in moderate pronation and the wrist closer to neutral. More time was spent in neutral and moderate ranges of wrist motion when subjects typed on the FIXED compared with the other two designs. With respect to the standard keyboard, typing productivity was reduced by 10% on the FIXED and 20% on the OPEN designs. No significant difference in preference was found between the standard and FIXED keyboards, both of which were preferred over the OPEN. It was concluded that, of the three keyboards evaluated, the FIXED design incorporated moderate changes to the standard keyboard. These changes promoted a more natural hand position while typing thereby reducing the potential for cumulative trauma disorders of the wrist. In addition, the FIXED design preserved a reasonable level of productivity and was well accepted by users.

Wrist and Forearm Posture from Typing on Split and Vertically Inclined Computer Keyboards

A study was conducted on 90 experienced office workers to determine how commercially available alternative computer keyboards affected wrist and forearm posture. The alternative keyboards tested had the QWERTY layout of keys and were of three designs: split fixed angle, split adjustable angle, and vertically inclined (tilted or tented). When set up correctly, commercially available split keyboards reduced mean ulnar deviation of the right and left wrists from 12 degrees to within 5 degrees of a neutral position compared with a conventional keyboard. The finding that split keyboards place the wrist closer to a neutral posture in the radial/ulnar plane substantially reduces one occupational risk factor of work-related musculoskeletal disorders (WMSDs): ulnar deviation of the wrist. Applications of this research include commercially available computer keyboard designs that typists can use and ergonomists can recommend to their clients in order to minimize wrist ulnar deviation from typing.

A Proof of the Exponentially Small Transversality of the Separatrices for the Standard Map

In 1984 V. F. Lazutkin [Laz84, LST89] obtained an asymptotic formula for the separatrix splitting angle for the standard map. The difficulty of this problem is related to the exponential smallness of the splitting with respect to a perturbation parameter. Lazutkin's proof was based on two conjectures. Probably, the original form of those conjectures was incorrect, but Lazutkin's method was very efficient and inspired a large number of studies on the exponentially small splitting of separatrices. The consequent works [Laz91, Laz92, GLS94] and [Gel96] prepared the base to fill all the gaps of the original proof. The present paper contains a complete and self-contained proof of a refined version of the original formula (formula (1.7) of the present paper). In this form the formula was obtained in [GLS94]. The proof is inspired by the ideas of Lazutkin's original paper [Laz84].

Microwave Gaussian beam splitting with a variable split angle by using a chiral lens

In this paper we present analysis and design of a chiral lens that is used to split a linearly polarized Gaussian beam into right‐circularly and left‐circularly polarized beams traveling in different directions. It will be shown that split beams remain Gaussian if the curvature of the lens is large in comparison with the beam width. Moreover, the split angle can be varied by changing the point of beam incidence on the curved surface of the lens. Parameters like the beam width and cross‐polarization ratio for the split beams are derived and computed.

Fabrication of spatial walk-off polarizing film exhibiting a large split angle by oblique silicon deposition

A spatial walk-off polarizing film with a large split angle was fabricated by use of the oblique deposition method. The film is composed of slanted needlelike microcolumns of a-Si that are separated by resultant fine voids. The polarization-splitting characteristics of the film were clearly observed. The maximum split angle at a wavelength of 1.55 microm was as large as 20 degrees , more than three times greater than those of existing polarizers such as those constructed of rutile and calcite.

Ion-exchanged diffractive elements in glass for substrate-mode optics

We recently demonstrated the use of continuous-phase ion-exchanged diffractive elements in glass for free-space optics. We extend our design methods to substrate-mode optics, which permits compact packing of miniature-sized free-space optical systems. We designed one-dimensional gratings for equal-intensity 1 ? 3 and 1 ? 5 beam splitting, assuming both planar and conical incidence angles. An experimental demonstration of a 1 ? 3 beam splitter with a uniformity error of 3.4% is presented.

Behavior of acoustic axes and internal conical refraction in LiNbO/sub 3/ and SrTiO/sub 3/ crystals placed in an external electric field

The behavior of acoustic axes and conical refraction are analyzed for lithium niobate and strontium titanate crystals, which are either mechanically squeezed or mechanically free and placed in an external electric field. Relying on numerical calculation, field dependencies of the acoustic axis shift and splitting angles have been elaborated, which are compared with the results obtained previously in the context of the theory of perturbations. External electric fields with the intensity E<10(7) V/m have yielded small (<1 degrees ) angles of acoustic axis splitting and shift; however, for greater field intensities, E>/=10(7) V/m, the rearrangement of the crystal's acoustic axes with respect to its initial position (E=O) assumes a "macroscopic nature". In particular, degeneracies having Poincare indexes with opposite signs may merge and "annihilate". We also first examined the variation of the conical refraction parameters versus the external electric field with transverse elastic waves which propagate along the acoustic axes of conical degeneracy in the above-mentioned materials. With actually achievable field strengths, the direction of energy velocity can be altered by several degrees. It is sufficient for the development of highly effective modulators, switchers, and acoustic wave gates to be used in various logic elements and other signal processing units.

Poly-Si/SiO/sub 2/ laminated walk-off polarizer having a beam-splitting angle of more than 20

A spatial walk-off polarizer having a split angle of more than 20/spl deg/ in both the 1.3 and 1.5 /spl mu/m wavelength regions has been fabricated for the first time. The polarizer consists of alternate laminated layers of poly-Si and silica. The new polarizer makes the best use of the characteristics of crystal Si, namely high refractive index, and low absorption coefficients in the longer wavelength regions. A rather simplified fabrication process that utilizes the RF sputtering method is also proposed, in which only the oxygen-intake valve is used to control the deposition of poly-Si and silica layers from a single-crystal Si target. The fabricated polarizer has beam splitting angles as large as 22 and 21/spl deg/ at wavelengths of 1.30 and 1.55 /spl mu/m, respectively, being roughly four times larger than those of rutile or calcite.

Ship grounding on rock—I. Theory

This paper presents a set of analytical expressions which can be used to calculate the reaction force on a ship bottom deformed by a conical rock with a rounded tip. Closed-form solutions are given for the resistance of inner and outer bottom plating, longitudinal stiffeners, girders and bulkheads and transverse frames, floors and bulkheads. The expressions are derived by use of an energy method or a type of ‘upper bound’ method which rigorously takes into account the effects of large plastic deformations, friction and fracture. A high level of generality for the methodology has been optained by postulating a global mode of deformation for the structure around the rock with one free parameter, the plate split angle, related to the shape of the deformation mode. It is assumed that intersections between structural components stay intact during the entire deformation process so the resistance of the individual structural members are derived according to the global deformation mode. The resistance of the entire structure is found by minimizing the energy dissipation from all the deformed members with respect to the plate split angle. In a subsequent paper (B.C. Simonsen, Ship grounding on rock—II. Validation and application, Marine structures 10 (1997) 563–584) it is shown that the theoretical model predicts the damage of four large scale tests and an accidental grounding with errors less than 10%. Moreover, it is illustrated by an example that the model evaluation of a grounding scenario is sufficiently fast to be used in a probabilistic framework in a Formal Safety Assessment.

Universal homoclinic bifurcations and chaos near double resonances

We study the dynamics near the intersection of a weaker and a stronger resonance inn-degree-of-freedom, nearly integrable Hamiltonian systems. For a truncated normal form we show the existence of (n−2)-dimensional hyperbolic invariant tori whose whiskers intersect inmultipulse homoclinic orbits with large splitting angles. The homoclinic obits are doubly asymptotic to solutions that “diffuse” across the weak resonance along the strong resonance. We derive a universalhomoclinic tree that describes the bifurcations of these orbits, which are shown to survive in the full normal form. We illustrate our results on a three-degree-of-freedom mechanical system.

A-SiC:H/SiO 2 Laminated Polarization Splitter for the Wavelength Region Longer Than 1.3 μm Prepared by Plasma-Enhanced Chemical Vapor Deposition

A laminated polarization splitter for the wavelength region longer than 1.3 μm is fabricated for the first time. It is composed of a-SiC:H/SiO 2 alternative multilayers prepared by plasma-enhanced chemical vapor deposition. Splitting behavior is also verified experimentally. It has low absorption loss even for the wavelength region around λ = 1.3 μm because the band-gap energy of a-Sic is larger than that of a-Si. The measured splitting angle is 13.8°, which is 2.4 times larger than the 5.7° splitting angle of rutile. The absorption loss of the multilayer is reduced to 1 × 10 -3 dB/μm at λ = 1.3 μm. The magnitude of the residual stress is 9.45 × 10 8 dyn/cm 2, which is about one-third of that prepared by the rf bias sputtering equipment which is used for another project of our group. The deposition rate of SiO 2, is increased to 135 nm/min, which is 27 times larger than that prepared by the sputtering equipment.

Fabrication And Characterization Of Polyimide Waveguides For Optical Interconnection

ABSTRACTThis paper reports the fabrication and characterization of polyimide branching waveguides for on-chip optical signal distribution in GaAs-based optoelectronic integrated circuits (OEICs). Low-loss polyimide s-bends and splitters with good splitting ratios and angles considerably larger than similar structures made from inorganic (e.g. LiNbO3) and semiconductor (e.g. GaAs, InP) materials, have been successfully fabricated and tested. The effects of the radius of curvature, splitter angle and cladding materials on the optical losses are discussed.

Characteristics of heavily carbon-doped GaAs by LPMOCVD and critical layer thickness

The carbon-doping characteristics of GaAs epilayers have been investigated by varying the growth parameters - V/III ratio and growth temperature. We have obtained the highest 1.4 × 10 20 cm -3 hole concentration with hole mobility 42 cm 2/V·s without using intentional doping source gases. The carbon incorporation increased with increasing growth temperature up to the critical temperature and above this temperature the carbon incorporation decreased. This critical temperature depends on input TMG flow rate. The peak energy of the PL intensity distribution was shifted to lower energy (red shift) and the full width at half maximum (FWHM) increased with increasing hole concentration. The (400) diffraction peak of the carbon-doped GaAs epilayer was split from the substrate GaAs peak. The split angle was 191.25 arc for the carbon-doped GaAs with 9 × 10 19 cm -3 hole concentration. We also have discussed the relationship between carbon-doping concentration and critical layer thickness ( L C ) by an excess stress model. The excess stress at which partial strain relief became observable was σ exc / μ = 0.0021. Thus we identified this excess stress as the critical excess stress for carbon-doped GaAs epilayers. If the excess stress was greater than this, the epilayers showed the surface cross-hatching.

Laminated polarization splitter with a large split angle

A new spatial walk-off polarizer with a large polarization-splitting angle is fabricated. The polarizer, which utilizes artificial anisotropic dielectrics, is composed of layers of periodically laminated a-Si:H/SiO2 thin films. The thickness of each layer is 67 nm, while the total number of the layers amounts to 1440. The measured polarization-splitting angle is 15.5° at λ=1.55 μm, which is 2.7 times larger than that of existing polarizers.

Experimental analysis of thermal fields in horizontally eccentric cylindrical annuli

This paper presents new experimental results on thermal field and heat transfer in a two-dimensional annulus between horizontally eccentric cylinders. The study is conducted by means of optical techniques, for 1.07×104≤Ra L≤8.27×104 and a wide eccentricity range. The horizontal eccentricity of the inner cylinder substantially alters the thermal field and the geometry of the plume, but, in analogy to the behaviour for vertical eccentricity, the average Nu is slightly affected in the investigated range of eccentricity. The concentric geometry is also considered mainly to validate the experimental technique and evaluate the accuracy of the adopted methodology by comparison with available results. Both shearing interferometer and reference beam interferometer are obtained by means of Wollaston prisms with appropriate splitting angles, so that the temperature and local Nu distributions may be evaluated quantitatively from the original pictures via digital image processing.

Experimental verification of a form-birefringent polarization splitter

Experimental verification is made of a new polarization splitter which utilizes artificial anisotropic dielectrics. The splitter is composed of layers of periodically laminated SiO2/TiO2 thin films. The SiO2 and TiO2 films are alternately deposited by rf sputtering and reactive dc sputtering, respectively. The thickness of each layer is 50 nm, while the total number of the layers amounts to 2000. The measured polarization split angles are 5.7° (λ=0.63 μm) and 5.1° (λ=1.3 μm), being roughly the same as those predicted.

Spatial walk-off polarizer utilizing artificial anisotropic dielectrics

We propose a new spatial walk-off polarizer that utilizes artificial anisotropic dielectrics. The polarizer is composed of two kinds of periodically laminated dielectric layer. We calculated the characteristics of the polarizer composed of periodically laminated a-Si/SiO(2) layers and found that the split angle between the ordinary wave and the extraordinary wave in the polarizer is more than three times larger than that in well-known birefringent crystals, e.g., rutile and calcite. The polarizer holds promise for the miniaturization of polarization beam splitters and polarization-independent isolators.

Wollaston prism with large split angle

The image formation through a Wollaston prism with large split angle is studied. Formulas for the split angle, approximate calculations of aberrations, and ray tracings are used. The most important aberrations found are astigmatism and anamorphic distortion. Tilting the Wollaston with respect to the incident beam may reduce these aberrations, and if the orientation of the optical axis in the first element is varied it is possible to cancel one of the two aberrations for both images simultaneously, while the other one is substantially reduced. With an adequate adjustment of all the construction parameters the images become sharp enough to allow the use of large split angles (approximately 15 degrees).

New Types of Polarizers Made from Crystals of the Calomel Group

AbstractThe present work deals with the applicability of the mercurous halide crystals to the production of polarizers of light. The wide transmission region of these crystals mainly in the infrared region allows to use them for wavelenghts up to about 20 m̈m for mercurous chloride and 30 m̈m for mecrurous bromide. Especially high double refraction allows a construction of classical polarizer types having very advantageous parameters, i.e. small thickness of the element and large angle of splitting of the ordinary and extraordinary ray. Besides, high double refraction allows an original design of single‐piece (monolithic) polarizers which are characterized by relatively simple treatment, high quality and low losses.

Digital Light Deflectors

Several electrooptic digital light deflection techniques have been proposed. The maximum number of resolvable deflection positions for all methods is determined, essentially, by economic reasons, the tolerable amount of background light, and aberrations. In this paper, three different types of deflection methods (split angle, total internal reflection, Wollaston prism) are described. Design, construction details, and performance of three deflector models are reported. Combined deflection systems use the advantageous properties of each of these methods to economically obtain the maximum number of resolvable deflection positions. A suggested combination to achieve 1024x1024 positions arranged in a two-dimensional field would consist of one total internal reflection stage, seven stages of split angles, and two stages of Wollaston prisms for each dimension.