Efficient Geometric Disassembly of Multiple Components from an Assembly Using Wave Propagation

2000 ◽  
Vol 122 (2) ◽  
pp. 179-184 ◽  
Author(s):  
Hari Srinivasan ◽  
Rajit Gadh
Keyword(s):  
Wave Propagation ◽  
Three Dimensional ◽  
Computation Time ◽  
Two Dimensional ◽  
New Approach ◽  
Multiple Components ◽  
Disassembly Sequence ◽  
Minimal Component ◽  
Selective Disassembly ◽  
The Waves

This paper analyzes the problem of disassembling multiple selected components from an assembly, defined as selective disassembly, and presents algorithms for efficient disassembly analysis of geometric models. Applications for selective disassembly include assembling, maintenance and recycling. A new approach called ‘Disassembly Wave Propagation’ is proposed to determine a selective disassembly sequence with minimal component removals from an assembly. This approach defines: (i) disassembly waves to topologically arrange the components denoting the disassembly order and (ii) intersection events between the waves to determine the selective disassembly sequences. In order to evaluate a minimal removal sequence in a feasible computation time, algorithms are proposed that prioritize and process the intersection events based on the order in which they occurred. The proposed algorithms analyze selective disassembly from the geometric perspective and are applicable for both two-dimensional and three-dimensional product assemblies. [S1050-0472(00)01402-1]

scholarly journals Quasi-two-dimensional approximation for numerical simulation of flows in engine ducts

2019 ◽  
Author(s):  
V. Vlasenko ◽  
A. Shiryaeva
Keyword(s):  
High Speed ◽  
Fuel Injection ◽  
Three Dimensional ◽  
Preliminary Design ◽  
Two Dimensional ◽  
Combustion Chambers ◽  
New Approach ◽  
One Dimensional ◽  
Dimensional Approximation ◽  
3D Flows

New quasi-two-dimensional (2.5D) approach to description of three-dimensional (3D) flows in ducts is proposed. It generalizes quasi-one-dimensional (quasi-1D, 1.5D) theories. Calculations are performed in the (x; y) plane, but variable width of duct in the z direction is taken into account. Derivation of 2.5D approximation equations is given. Tests for verification of 2.5D calculations are proposed. Parametrical 2.5D calculations of flow with hydrogen combustion in an elliptical combustor of a high-speed aircraft, investigated within HEXAFLY-INT international project, are described. Optimal scheme of fuel injection is found and explained. For one regime, 2.5D and 3D calculations are compared. The new approach is recommended for use during preliminary design of combustion chambers.

A New Approach to Thin Aerofoil Theory

1951 ◽  
Vol 3 (3) ◽  
pp. 193-210 ◽  
Author(s):  
M.J. Lighthill
Keyword(s):  
Three Dimensional ◽  
Leading Edge ◽  
Approximate Solutions ◽  
Radius Of Curvature ◽  
Two Dimensional ◽  
General Technique ◽  
New Approach ◽  
Flow Problems ◽  
Physical Problems ◽  
First Approximation

SummaryThe general technique for rendering approximate solutions to physical problems uniformly valid is here applied to the simplest form of the problem of correcting the theory of thin wings near a rounded leading edge. The flow investigated is two-dimensional, irrotational and incompressible, and therefore the results do not materially add to our already extensive knowledge of this subject, but the method, which is here satisfactorily checked against this knowledge, shows promise of extension to three-dimensional, and compressible, flow problems.The conclusion, in the problem studied here, is that the velocity field obtained by a straightforward expansion in powers of the disturbances, up to and including either the first or the second power, with coefficients functions of co-ordinates such that the leading edge is at the origin and the aerofoil chord is one of the axes, may be rendered a valid first approximation near the leading edge, as well as a valid first or second approximation away from it, if the whole field is shifted downstream parallel to the chord for a distance of half the leading edge radius of curvature ρL. It follows that the fluid speed on the aerofoil surface, as given on such a straightforward second approximation as a function of distance x along the chord, similarly is rendered uniformly valid (see equation (52)) if the part singular like x-1 is subtracted and the remainder is multiplied by .

2.5D AND 3D GREEN'S FUNCTIONS FOR ACOUSTIC WEDGES: IMAGE SOURCE TECHNIQUE VERSUS A NORMAL MODE APPROACH

2013 ◽  
Vol 21 (01) ◽  
pp. 1250025 ◽  
Author(s):  
A. TADEU ◽  
E. G. A. COSTA ◽  
J. ANTÓNIO ◽  
P. AMADO-MENDES
Keyword(s):  
Wave Propagation ◽  
Normal Mode ◽  
Green's Functions ◽  
Green’S Functions ◽  
Three Dimensional ◽  
Element Formulation ◽  
Two Dimensional ◽  
Image Source ◽  
Point Pressure ◽  
Fluid Channel

2.5D and 3D Green's functions are implemented to simulate wave propagation in the vicinity of two-dimensional wedges. All Green's functions are defined by the image-source technique, which does not account directly for the acoustic penetration of the wedge surfaces. The performance of these Green's functions is compared with solutions based on a normal mode model, which are found not to converge easily for receivers whose distance to the apex is similar to the distance from the source to the apex. The applicability of the image source Green's functions is then demonstrated by means of computational examples for three-dimensional wave propagation. For this purpose, a boundary element formulation in the frequency domain is developed to simulate the wave field produced by a 3D point pressure source inside a two-dimensional fluid channel. The propagating domain may couple different dipping wedges and flat horizontal layers. The full discretization of the boundary surfaces of the channel is avoided since 2.5D Green's functions are used. The BEM is used to couple the different subdomains, discretizing only the vertical interfaces between them.

Numerical study of Love wave propagation

Geophysics ◽  
1983 ◽  
Vol 48 (7) ◽  
pp. 833-853 ◽  
Author(s):  
K. R. Kelly
Keyword(s):  
Numerical Modeling ◽  
Wave Propagation ◽  
Love Wave ◽  
Fourier Transforms ◽  
Narrow Band ◽  
Numerical Study ◽  
Two Dimensional ◽  
Band Pass ◽  
The Waves ◽  
Insight Into

Love wave propagation is studied by investigating numerical modeling results for several examples of geologic interest. The modal characteristics of the results are clarified by the use of narrow band‐pass filters and two‐dimensional Fourier transforms in range and time. Such processing makes it possible to study changes in phase and group velocity for the various modes and to locate points of reflection. This permits one to gain insight into changes in the physical properties of the surface channel supporting the waves.

Study of the Effect of Boundary Conditions on Residual Stresses in Welding Using Element Birth and Element Movement Techniques

2003 ◽  
Vol 125 (4) ◽  
pp. 432-439 ◽  
Author(s):  
Ihab F. Z. Fanous ◽  
Maher Y. A. Younan ◽  
Abdalla S. Wifi
Keyword(s):  
Residual Stresses ◽  
Boundary Conditions ◽  
Three Dimensional ◽  
Welding Process ◽  
Computation Time ◽  
The Other ◽  
Two Dimensional ◽  
The Media ◽  
Three Dimensional Models ◽  
Element Movement

The structure in which the welding process is performed highly affects the residual stresses generated in the welding. This effect is simulated by choosing the appropriate boundary conditions in modeling the welding process. The major parameters of the boundary conditions are the method by which the base metal is being fixed and the amount of heat being applied through the torch. Other parameters may include the coefficients of thermal heat loss from the plate which may simulate the media in which the welding is taking place. In modeling the welding process, two-dimensional forms of approximation were developed in analyzing most of the models of such problem. Three-dimensional models analyzing the welding process were developed in limited applications due to its high computation time and cost. With the development of new finite element tools, namely the element movement technique developed by the authors, full three-dimensional analysis of the welding process is becoming in hand. In the present work, three different boundary conditions shall be modeled comparing their effect on the welding. These boundary conditions shall be applied to two models of the welding process: one using the element birth technique and the other using the element movement technique showing the similarity in their responses verifying the effectiveness of the latter being accomplished in a shorter time.

scholarly journals Wave resistance: Some cases of three-dimensional fluid motion

1919 ◽  
Vol 95 (670) ◽  
pp. 354-365 ◽  
Keyword(s):  
Surface Pressure ◽  
Fluid Motion ◽  
Three Dimensional ◽  
Wave Resistance ◽  
The Other ◽  
Two Dimensional ◽  
Pressure System ◽  
Submerged Body ◽  
Submerged Sphere ◽  
The Waves

1. Calculations of wave resistance, corresponding to a pressure system travelling over the surface, have hitherto been limited to two-dimensional fluid motion; in those cases, the distribution of pressure on the surface is one-dimensional, and the regular waves produced have straight, parallel crests. The object of the following paper is to work out some cases when the surface pressure is two-dimensional and the wave pattern is like that produced by a ship. A certain pressure system symmetrical about a point is first examined, and more general distributions are obtained by superposition. By combining two simple systems of equal magnitude, one in rear of the other, we obtain results which show interesting interference effects. In similar calculations with line pressure systems, at certain speeds the waves due to one system cancel out those due to the other, and the wave resistance is zero; the corresponding ideal form of ship has been called a wave-free pontoon. Such cases of perfect interference do not occur in three-dimensional problems; the graph showing the variation of wave resistance with velocity has the humps and hollows which are characteristic of the resistance curves of ship models. Although the main object is to show how to calculate the wave resistance for assigned surface pressures of considerable generality, it is of interest to interpret some of the results in terms of a certain related problem. With certain limitations, the waves produced by a travelling surface pressure are such as would be caused by a submerged body of suitable form. The expression for the wave resistance of a submerged sphere, given in a previous paper, is confirmed by the following analysis. It is also shown how to extend the method to a submerged body whose form is derived from stream lines obtained by combining sources and siuks with a uniform stream; in particular, an expression is given for the wave resistance of a prolate spheroid moving in the direction of its axis.

Supported two- and three-dimensional vanadium oxide species on the surface of β-SiC

2017 ◽  
Vol 7 (17) ◽  
pp. 3707-3714 ◽  
Author(s):  
Carlos A. Carrero ◽  
Samuel P. Burt ◽  
Fangying Huang ◽  
Juan M. Venegas ◽  
Alyssa M. Love ◽  
...  
Keyword(s):  
Vanadium Oxide ◽  
Scale Up ◽  
Three Dimensional ◽  
Two Dimensional ◽  
New Approach ◽  
Propane Odh

Dispersing two-dimensional VOx species on β-SiC offers a new approach to scale up propane ODH.

scholarly journals Studi Penjalaran Gelombang Laut di Pulau Panjang, Kabupaten Jepara

2021 ◽  
Vol 10 (1) ◽  
pp. 75-87
Author(s):  
Tri Widya Laksana Putra ◽  
Muhammad Zainuri ◽  
Denny Nugroho Sugianto
Keyword(s):  
Wave Propagation ◽  
Direct Measurement ◽  
Hydrodynamic Model ◽  
High Tide ◽  
Acoustic Doppler Current Profiler ◽  
Wind Data ◽  
Two Dimensional ◽  
Single Beam ◽  
Current Profiler ◽  
The Waves

Pulau Panjang terletak di sebelah barat pantai Kota Jepara memiliki luas wilayah teritorial 30 Ha dan dimanfaatan sebagai wisata pulau, wisata ziarah, dan lokasi penangkapan ikan. Kombinasi kondisi gelombang ekstrim dan air pasang mengakibatkan tekanan kuat di pesisir Pulau Panjang sehingga menimbulkan kerusakan pada fasilitas wisata. Berdasarkan hal tersebut, diperlukan adanya analisis mengenai karakteristik penjalaran gelombang laut untuk menunjang segala jenis kegiatan masyarakat. Analisis penjalaran gelombang dilakukan melalui pendekatan pemodelan numerik hidrodinamika dua dimensi (two-dimensional hydrodynamic model). Data primer yang digunakan adalah data pengukuran langsung nilai gelombang menggunakan instrument Acoustic Doppler Current Profiler dan pengukuran langsung data batimetri menggunakan instrument single-beam echosounder. Data sekunder meliputi data angin (1999 – 2019) yang didapatkan dari portal unduh data di www.ogimet.com, data pasang surut BMKG dan data batimetri dari Badan Informasi Geospasial. Tinggi gelombang signifikan (Hs) dan periode signifikan (Ts) didapatkan dari konversi data angin menjadi nilai Hs dan Ts dengan metode DNS. Nilai Hs dan Ts maksimal setiap arah mata angin mmenjadi input perhitungan model hidrdodinamika. Hasil spasial penjalaran gelombang tertinggi terjadi pada arah datang gelombang dari arah timur laut, tenggara dan barat.  Penjalaran gelombang di Pulau Panjang menciptakan daerah terlindung di sisi seberang dari arah datang gelombang dan saat gelombang endekati pantai penjalaran gelombang mengikuti kontur garis pantai diikuti dengan melemahnya kecepatan rambat gelombang. Panjang Island is located on the west coast of Jepara City and has a territorial area of 30 hectares and is used as island tourism, pilgrimage tours, and fishing locations. The combination of extreme wave conditions and high tide resulted in strong force on the coast of Panjang Island causing damage to tourist facilities. Based on this, it is necessary to have an characteristics analysis of the sea waves propagation to support all types of community activities. Analysis of the propagation of the waves was carried out using a two-dimensional hydrodynamic model approach. The primary data used are direct measurement data of wave values using the Acoustic Doppler Current Profiler instrument and direct measurement of bathymetric data using a single-beam echosounder instrument. Secondary data includes wind data (1999 - 2019) obtained from the data download portal at www.ogimet.com, BMKG tidal data and bathymetry data from the Geospatial Information Agency. Significant wave height (Hs) and significant period (Ts) are obtained from the conversion of wind data into Hs and Ts values using the DNS method. The maximum Hs and Ts values for each cardinal direction are the input for calculating the hydrodynamic model. The highest spatial results of wave propagation occur in the coming direction of waves from the northeast, southeast and west. The wave propagation in Panjang Island creates a protected area on the opposite side from the direction of the waves coming and when the waves approach the coast the propagation of the waves follow the contours of the coastline followed by a weakening of the wave propagation speed.

The relationship between two- and three-dimensional elastic-wave propagation

1971 ◽  
Vol 61 (6) ◽  
pp. 1583-1588 ◽  
Author(s):  
C. N. G. Dampney
Keyword(s):  
Wave Propagation ◽  
Elastic Wave ◽  
Three Dimensional ◽  
Elastic Wave Propagation ◽  
Simple Relationship ◽  
Two Dimensional ◽  
Intrinsic Interest ◽  
Cylindrically Symmetric ◽  
The Relationship ◽  
Dimensional Wave

abstract A technique similar to inverting Abel's equation is used to invert the descent of dimensions method between three-dimensional, cylindrically-symmetric and two-dimensional wave propagation. The end result is a very simple relationship between the two types of wave propagation. Apart from its intrinsic interest, the large number of two-dimensional studies reported in the literature could now be related to their three-dimensional counterparts.

Sign in / Sign up

Export Citation Format

Share Document