Compensation of lens manufacturing errors and inhomogeneities by filtering view images in three-dimensional lenticular displays

2021 ◽  
Author(s):  
Jundong Zhou ◽  
Valeriano Ferreras Paz ◽  
Wilhelm Stork
Keyword(s):  
Three Dimensional ◽  
Manufacturing Errors

A Three-Dimensional Load Sharing Model of Planetary Gear Sets Having Manufacturing Errors

2015 ◽  
Author(s):  
Nicholas D. Leque ◽  
Ahmet Kahraman
Keyword(s):  
Three Dimensional ◽  
Planetary Gear ◽  
Load Sharing ◽  
Distribution Model ◽  
Gear Mesh ◽  
Position Errors ◽  
Proposed Model ◽  
Manufacturing Errors ◽  
Manufacturing Tolerancing ◽  
Planetary Gear Sets

Planet-to-planet load sharing is a major design and manufacturing tolerancing issue in planetary gear sets. Planetary gear sets are advantageous over their countershaft alternatives in many aspects, provided that each planet branch carries a reasonable, preferably equal, share of the torque transmitted. In practice, the load shared among the planets is typically not equal due to the presence of various manufacturing errors. This study aims at enhancing the models for planet load sharing through a three-dimensional formulation of N-planet helical planetary gear sets. Apart from previous models, the proposed model employs a gear mesh load distribution model to capture load and time dependency of the gear meshes iteratively. It includes all three types of manufacturing errors, namely constant errors such as planet pinhole position errors and pinhole diameter errors, constant but assembly dependent errors such as nominal planet tooth thickness errors, planet bore diameter errors, and rotation and assembly dependent errors such as gear eccentricities and run-outs. At the end, the model is used to show combined influence of these errors on planet load sharing to aid designers on how to account for manufacturing tolerances in the design of the gears of a planetary gear set.

Numerical Analysis of the Impact of Manufacturing Errors on the Structural Stiffness of Foil Bearings

2017 ◽  
Author(s):  
Aurelian Fatu ◽  
Mihai Arghir
Keyword(s):  
Standard Deviation ◽  
Mechanical Characteristics ◽  
Three Dimensional ◽  
Simplified Model ◽  
Radial Clearance ◽  
Foil Bearings ◽  
Bump Height ◽  
Manufacturing Errors ◽  
The Impact ◽  
Bearing Structure

The dynamic characteristics of foil bearings operating at high rotation speeds depend very much on the mechanical characteristics of the foil structure. For this reason, the stiffness and damping of the structure of foil bearings is a problem that is the focus of many analyses. The mechanical characteristics of the foil structure (top and bump foil) are analyzed either by using a simple approach obtained for an isolated bump modeled as a beam or with more elaborate ones taking into account the three-dimensional nature of the bumps and their mutual interactions. These two kinds of models give different foil structure stiffness, with lower values for the simplified model. However, the published experimental results of the foil bearing structure tend to validate the simplified model. The present paper explains the differences between the simplified and the elaborate models by taking into account the manufacturing errors of the foil structure. A three-dimensional model based on the non-linear theory of elasticity is developed. The model offers a unique insight into the way the bearing structure deforms when the rotor is incrementally pushed into the foil structure. Three realistic manufacturing errors, bump height, bump length and radius of the bump foil are analyzed. Bump height and length vary following a normal distribution with a given standard deviation while the radius of the bump foil is given a waviness form with an imposed peak-to-peak amplitude. Three to five cases were calculated for each kind of error. Results show that only the manufacturing errors of the bump height affect the stiffness of the foil structure by diminishing its values. Height errors of 20 μm standard deviation (4% of the average bump height and 60% of the radial clearance) may induce a 40–50% reduction of the stiffness of the foil structure, i.e. in the range of the predictions of the simplified model.

scholarly journals INFLUENCE OF CONSTRUCTIVE ARRANGEMENT DECISIONS AND MANUFACTURING ERRORS OF ELEMENTS OF THE WIDEBAND HORN ANTENNA ON ITS TECHNICAL CHARACTERISTICS

2019 ◽  
pp. 98-109
Author(s):  
O. A. Nahorniuk ◽  
Y. O. Kolos
Keyword(s):  
Three Dimensional ◽  
Horn Antenna ◽  
Significant Deterioration ◽  
Dielectric Characteristics ◽  
Insulating Material ◽  
Specialized Software ◽  
Computer Aided ◽  
Manufacturing Errors ◽  
Bolt Connection ◽  
Constituent Elements

The results of the research of the main releases of arrangement of horn antenna with two ridges, which differ in the ways of fixing the elements: bolt connection (rivets) and soldering (welding), are presented in the article. The influence of inaccuracies in the manufacture of particular antenna elements (errors in the geometric dimensions of the waveguide and the horn aperture, errors in the location of the feed pin, differences in the relative permittivity of the insulating material from the calculated one and others) and their interconnections (the width of the slots between the horn aperture plates, the distance between the ridges at the feeding point) on the main antenna characteristics (voltage standing-wave ratio, gain, radiation pattern). The researches were carried out using software environments for computer-aided designing, modeling and optimizing three-dimensional electromagnetic systems ANTENNA MAGUS and CST STUDIO SUITE. It has been found that with the same accuracy of manufacturing the constituent elements of a wideband horn antenna, the considered releases of arrangement provide similar technical characteristics. The research of manufacturing errors of the antenna elements and their interconnections showed that the longitudinal waveguide dimensions, the distance between the ridges at the point of excitation, the location and diameter of the feed pin, and also the dielectric characteristics of the insulating material have the greatest influence on the characteristics of the antenna. It has been established that a change in particular antenna sizes by 10% can lead to a significant deterioration in its matching. The system of tolerances for the sizes and connections of antenna elements, the adherence of which will ensure the conformity of the characteristics of the manufactured example to those obtained in the process of modeling and optimization using specialized software, is justified.

Numerical Analysis of the Impact of Manufacturing Errors on the Structural Stiffness of Foil Bearings

2017 ◽  
Vol 140 (4) ◽  
Author(s):  
Aurelian Fatu ◽  
Mihai Arghir
Keyword(s):  
Standard Deviation ◽  
Mechanical Characteristics ◽  
Three Dimensional ◽  
Simplified Model ◽  
Radial Clearance ◽  
Foil Bearings ◽  
Bump Height ◽  
Manufacturing Errors ◽  
The Impact ◽  
Bearing Structure

The dynamic characteristics of foil bearings operating at high rotation speeds depend very much on the mechanical characteristics of the foil structure. For this reason, the stiffness and damping of the structure of foil bearings are problems that are the focus of many analyses. The mechanical characteristics of the foil structure (top and bump foil) are analyzed either by using a simple approach obtained for an isolated bump modeled as a beam or with more elaborate ones taking into account the three-dimensional nature of the bumps and their mutual interactions. These two kinds of models give different foil structure stiffness, with lower values for the simplified model. However, the published experimental results of the foil bearing structure tend to validate the simplified model. The present paper explains the differences between the simplified and the elaborate models by taking into account the manufacturing errors of the foil structure. A three-dimensional model based on the nonlinear theory of elasticity is developed. The model offers a unique insight into the way the bearing structure deforms when the rotor is incrementally pushed into the foil structure. Three realistic manufacturing errors, bump height, bump length, and radius of the bump foil, are analyzed. Bump height and length vary following a normal distribution with a given standard deviation while the radius of the bump foil is given a waviness form with an imposed peak-to-peak amplitude. Three to five cases were calculated for each kind of error. Results show that only the manufacturing errors of the bump height affect the stiffness of the foil structure by diminishing its values. Height errors of 20 μm standard deviation (4% of the average bump height and 60% of the radial clearance) may induce a 40–50% reduction of the stiffness of the foil structure, i.e., in the range of the predictions of the simplified model.

scholarly journals Detection and Visualization of Manufacturing Errors of Internal Cavity Structural Parts

2020 ◽  
Author(s):  
Li-Ming Duan ◽  
Lei Si ◽  
Xue-Qing Luo ◽  
Jia-Hang Wu ◽  
Cheng Fang
Keyword(s):  
Three Dimensional ◽  
Measurement Model ◽  
Internal Cavity ◽  
Manufacturing Error ◽  
Dimensional Measurement ◽  
Manufacturing Errors ◽  
Three Dimensional Measurement ◽  
Industrial Ct ◽  
Structural Parts ◽  
Cylindricity Error

Abstract Aiming at the difficulty of manufacturing error detection of internal cavity structural parts, a detection method of common manufacturing error based on industrial CT images was proposed. Firstly, the image sequence of part scanned by an industrial CT machine is converted into a three-dimensional measurement model; Then, the registration of the three-dimensional measurement model with the original design model is completed; The surface information of the part is obtained by segmenting surfaces of the three-dimensional measurement model; Next, the datum surface is selected, the error value of the test surface is calculated after selecting datum surface; Finally, the detection result is obtained by comparing the error value with the tolerance value, analyzing the result and the areas that do not meet the tolerance requirements is visualized in the developed software system. The common manufacturing errors of complex inner cavity parts can be detected by the method, such as dimension error of length, planeness error, cylindricity error, parallelism and perpendicularity error of face-to-face, at the same time, it can intuitively show the area whose manufacturing errors in the cavity structure of the parts are not satisfied, which provides a basis for judging the quality of manufacturing and processing of parts.

A Three-Dimensional Load Sharing Model of Planetary Gear Sets Having Manufacturing Errors

2017 ◽  
Vol 139 (3) ◽  
Author(s):  
N. Leque ◽  
A. Kahraman
Keyword(s):  
Three Dimensional ◽  
Planetary Gear ◽  
Load Sharing ◽  
Distribution Model ◽  
Gear Mesh ◽  
Position Errors ◽  
Proposed Model ◽  
Manufacturing Errors ◽  
Manufacturing Tolerancing ◽  
Planetary Gear Sets

Planet-to-planet load sharing is a major design and manufacturing tolerancing issue in planetary gear sets. Planetary gear sets are advantageous over their countershaft alternatives in many aspects, provided that each planet branch carries a reasonable, preferably equal, share of the torque transmitted. In practice, the load shared among the planets is typically not equal due to the presence of various manufacturing errors. This study aims at enhancing the models for planet load sharing through a three-dimensional (3D) formulation of N planet helical planetary gear sets. Apart from previous models, the proposed model employs a gear mesh load distribution model to capture load and time dependency of the gear meshes iteratively. It includes all the three types of manufacturing errors, namely, constant errors such as carrier pinhole position errors and pinhole diameter errors, constant but assembly dependent errors such as nominal planet tooth thickness errors, planet bore diameter errors, and rotation, and assembly dependent errors such as gear eccentricities and run-outs. At the end, the model is used to show combined influence of these errors on planet load sharing to aid designers on how to account for manufacturing tolerances in the design of the gears of a planetary gear set.

The orbit of Pluto over a long interval of time

1966 ◽  
Vol 25 ◽  
pp. 227-229 ◽  
Author(s):  
D. Brouwer
Keyword(s):  
Periodic Orbit ◽  
Numerical Integration ◽  
Restricted Problem ◽  
Three Dimensional ◽  
The Third ◽  
Circular Restricted Problem ◽  
Resonance Relation

The paper presents a summary of the results obtained by C. J. Cohen and E. C. Hubbard, who established by numerical integration that a resonance relation exists between the orbits of Neptune and Pluto. The problem may be explored further by approximating the motion of Pluto by that of a particle with negligible mass in the three-dimensional (circular) restricted problem. The mass of Pluto and the eccentricity of Neptune's orbit are ignored in this approximation. Significant features of the problem appear to be the presence of two critical arguments and the possibility that the orbit may be related to a periodic orbit of the third kind.

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