Three-Dimensional and Shell-Theory Analysis of Elastic Waves in a Hollow Sphere: Part 2—Numerical Results

1969 ◽  
Vol 36 (3) ◽  
pp. 440-444 ◽  
Author(s):  
A. H. Shah ◽  
C. V. Ramkrishnan ◽  
S. K. Datta
Keyword(s):  
Elastic Waves ◽  
Three Dimensional ◽  
Numerical Results ◽  
Mode Analysis ◽  
Theory Analysis ◽  
Frequency Spectra ◽  
The Past ◽  
Shell Analysis ◽  
Shell Equations ◽  
Thick Shells

In this Part 2 of the paper, numerical results obtained through an IBM 7044 digital computer are presented. Frequency values for the two classes of vibrations for different values of n are calculated from the exact frequency equations and also from the shell equations. Comparisons are made with the exact frequency spectra of those obtained from the present six-mode shell analysis and other available shell and membrane analyses. It is found that the lowest branches of the frequency spectra for the two classes of vibrations obtained by the six-mode analysis agree very well with the exact ones, even for very thick shells, whereas other shell analysis done in the past make erroneous predictions when the thickness-to-radius ratio of the shell is greater than 10 percent.

A Note on Three-Dimensional Supercavitating Hydrofoils

1975 ◽  
Vol 19 (03) ◽  
pp. 164-165
Author(s):  
A. J. Acosta ◽  
O. Furuya
Keyword(s):  
Experimental Data ◽  
Three Dimensional ◽  
Numerical Results ◽  
Experimental Results ◽  
Surface Theory ◽  
Finite Span ◽  
The Past ◽  
Lifting Surface ◽  
Experimental Findings

The three-dimensional or finite-span effect on supercavitating hydrofoils has received much attention in recent years. Among others may be mentioned the work of Tsen and Gullbaud [1], 3 who give the numerical results of their own fully linearized supercavitating lifting-surface theory together with some experimental data, both their own and from other sources. The numerical results are somewhat different from what one might expect based on existing theories, and some of the experimental findings appear to differ from previously published results. The purpose of this brief note is to compare some of the theoretical and experimental results from reference [1] with other recent works both for fully linearized treatments (valid only for vanishing angles of attack), and nonlinear theories and other experimental data that have been used in the past.

Three-Dimensional and Shell-Theory Analysis of Elastic Waves in a Hollow Sphere: Part 1—Analytical Foundation

1969 ◽  
Vol 36 (3) ◽  
pp. 431-439 ◽  
Author(s):  
A. H. Shah ◽  
C. V. Ramkrishnan ◽  
S. K. Datta
Keyword(s):  
Elastic Waves ◽  
Shell Theory ◽  
Three Dimensional ◽  
Frequency Equation ◽  
Wave Number ◽  
Normal Strain ◽  
Theory Analysis ◽  
Analytical Foundation ◽  
Transverse Normal Strain ◽  
Approximate Equations

In Part 1 of this paper an exact analysis of the nonaxisymmetric wave propagation in a hollow elastic sphere is presented. It is found that the characteristic frequency equation is independent of the longitudinal wave number. Approximate equations for thin shells and membranes are derived by way of asymptotic expansions. In general, the vibrations fall into two distinct classes, one of which is equivoluminal. Also included in the paper is a six-mode shell theory in which the effects of transverse normal strain are included. A technique due to van der Neut is used to separate the governing partial differential equations whereby two frequency equations corresponding to the two classes of vibrations are obtained.

Mitochondrial Reconstructions Based on Serial Thick Sections and HVEM

1975 ◽  
Vol 33 ◽  
pp. 286-287
Author(s):  
Jerome J. Paulin
Keyword(s):  
Imaging Techniques ◽  
Three Dimensional ◽  
Posterior Pole ◽  
Dimensional Structure ◽  
Stereo Imaging ◽  
Thin Sections ◽  
Anatomical Features ◽  
The Past ◽  
Cellular Components ◽  
Mitochondrial Reticulum

Within the past decade it has become apparent that HVEM offers the biologist a means to explore the three-dimensional structure of cells and/or organelles. Stereo-imaging of thick sections (e.g. 0.25-10 μm) not only reveals anatomical features of cellular components, but also reduces errors of interpretation associated with overlap of structures seen in thick sections. Concomitant with stereo-imaging techniques conventional serial Sectioning methods developed with thin sections have been adopted to serial thick sections (≥ 0.25 μm). Three-dimensional reconstructions of the chondriome of several species of trypanosomatid flagellates have been made from tracings of mitochondrial profiles on cellulose acetate sheets. The sheets are flooded with acetone, gluing them together, and the model sawed from the composite and redrawn.The extensive mitochondrial reticulum can be seen in consecutive thick sections of (0.25 μm thick) Crithidia fasciculata (Figs. 1-2). Profiles of the mitochondrion are distinguishable from the anterior apex of the cell (small arrow, Fig. 1) to the posterior pole (small arrow, Fig. 2).

Effects of stator splitter blades on aerodynamic performance of a single-stage transonic axial compressor

2020 ◽  
Vol 14 (4) ◽  
pp. 7369-7378
Author(s):  
Ky-Quang Pham ◽  
Xuan-Truong Le ◽  
Cong-Truong Dinh
Keyword(s):  
Stokes Equations ◽  
Three Dimensional ◽  
Axial Compressor ◽  
Aerodynamic Performance ◽  
Numerical Results ◽  
Single Stage ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Operating Stability ◽  
Length Coverage

Splitter blades located between stator blades in a single-stage axial compressor were proposed and investigated in this work to find their effects on aerodynamic performance and operating stability. Aerodynamic performance of the compressor was evaluated using three-dimensional Reynolds-averaged Navier-Stokes equations using the k-e turbulence model with a scalable wall function. The numerical results for the typical performance parameters without stator splitter blades were validated in comparison with experimental data. The numerical results of a parametric study using four geometric parameters (chord length, coverage angle, height and position) of the stator splitter blades showed that the operational stability of the single-stage axial compressor enhances remarkably using the stator splitter blades. The splitters were effective in suppressing flow separation in the stator domain of the compressor at near-stall condition which affects considerably the aerodynamic performance of the compressor.

To the theory analysis of tightness of tank of pressure testing

2019 ◽  
Vol 5 (4) ◽  
pp. 129-142
Author(s):  
Vladislav Sh. Shagapov ◽  
Ismagilyan G. Khusainov ◽  
Emiliya V. Galiakbarova ◽  
Zulfya R. Khakimova
Keyword(s):  
Relaxation Time ◽  
Three Dimensional ◽  
Petroleum Products ◽  
Technical Condition ◽  
Excess Pressure ◽  
Soil Parameters ◽  
Theory Analysis ◽  
Pressure Testing ◽  
Tank Pressure ◽  
Over Time

This article studies the process of relaxation of the pressure in a tank with the damaged area of the wall after pressure-testing. The authors use different methods for the diagnosis of the technical condition of objects of petroleum products storage. Pressure testing is one of nondestructive methods. The rate of pressure decrease is characteristic of the system tightness. This article studies the cases of ground and underground location of the tank. Pressure testing involves excess pressure inside of a tank and observing its decrease. Over time, one can assess the integrity of the system. This has required creating mathematical models to account the filtration of the liquid depending on the location of the tank. The results include the analytical solution of the task and the formulas for describing the dependence of the relaxation time of pressure in the tank from the liquid and soil parameters, geometry of the tank, and the damaged portion of the wall. The two- and three-dimensional cases of liquids filtration for the case of underground location of the tank were considered. The results of some numerical calculations of the dependence of reduction time and the time of half-life pressure from the area of the damaged portion of the wall were shown. The obtained solutions allow assessing the extent of the damaged area by the pressure testing with known values of tank, liquid, and soil.

scholarly journals Midface Reconstruction: Planning and Outcome

2020 ◽  
Vol 53 (03) ◽  
pp. 324-334
Author(s):  
Gautam Biswas
Keyword(s):  
Digital Imaging ◽  
3D Structure ◽  
Three Dimensional ◽  
The Past ◽  
Complex Anatomy ◽  
Osseointegrated Implants ◽  
Low Profile ◽  
3D Printed ◽  
Midface Reconstruction ◽  
Reconstruction Planning

Abstract Reconstruction of the complex anatomy and aesthetics of the midface is often a challenge. A careful understanding of this three-dimensional (3D) structure is necessary. Anticipating the extent of excision and its planning following oncological resections is critical.In the past over two decades, with the advances in microsurgical procedures, contributions toward the reconstruction of this area have generated interest. Planning using digital imaging, 3D printed models, osseointegrated implants, and low-profile plates, has favorably impacted the outcome. However, there are still controversies in the management: to use single composite tissues versus multiple tissues; implants versus autografts; vascularized versus nonvascularized bone; prosthesis versus reconstruction.This article explores the present available options in maxillary reconstruction and outlines the approach in the management garnered from past publications and experiences.

scholarly journals The Study of Three-Dimensional Fingerprint Recognition in Cultural Heritage

2021 ◽  
Vol 14 (4) ◽  
pp. 1-20
Author(s):  
Dzemila Sero ◽  
Isabelle Garachon ◽  
Erma Hermens ◽  
Robert Van Liere ◽  
Kees Joost Batenburg
Keyword(s):  
Image Processing ◽  
Cultural Heritage ◽  
Three Dimensional ◽  
Fingerprint Recognition ◽  
Person Identification ◽  
Imaging Technologies ◽  
The Past ◽  
Reconstruction Methods ◽  
Cultural Systems ◽  
Digital Fingerprint

Fingerprints play a central role in any field where person identification is required. In forensics and biometrics, three-dimensional fingerprint-based imaging technologies, and corresponding recognition methods, have been vastly investigated. In cultural heritage, preliminary studies provide evidence that the three-dimensional impressions left on objects from the past (ancient fingerprints) are of paramount relevance to understand the socio-cultural systems of former societies, to possibly identify a single producer of multiple potteries, and to authenticate the artist of a sculpture. These findings suggest that the study of ancient fingerprints can be further investigated and open new avenues of research. However, the potential for capturing and analyzing ancient fingerprints is still largely unexplored in the context of cultural heritage research. In fact, most of the existing studies have focused on plane fingerprint representations and commercial software for image processing. Our aim is to outline the opportunities and challenges of digital fingerprint recognition in answering a range of questions in cultural heritage research. Therefore, we summarize the fingerprint-based imaging technologies, reconstruction methods, and analyses used in biometrics that could be beneficial to the study of ancient fingerprints in cultural heritage. In addition, we analyze the works conducted on ancient fingerprints from potteries and ceramic/fired clay sculptures. We conclude with a discussion on the open challenges and future works that could initiate novel strategies for ancient fingerprint acquisition, digitization, and processing within the cultural heritage community.

Design and Marker-Based Validation of a Biplane Fluoroscopy System for Studying the Foot and Ankle

2012 ◽  
Author(s):  
Joseph M. Iaquinto ◽  
Richard Tsai ◽  
Michael J. Fassbind ◽  
David R. Haynor ◽  
Bruce J. Sangeorzan ◽  
...  
Keyword(s):  
Precise Measurement ◽  
Three Dimensional ◽  
The Body ◽  
Initial Evaluation ◽  
Foot And Ankle ◽  
Research Groups ◽  
The Past ◽  
Model Based ◽  
Biplane Fluoroscopy ◽  
Model Based Analysis

The ability to accurately measure three dimensional (3D) bone kinematics is key to understanding the motion of the joints of the body, and how such motion is altered by injury, disease, and treatment. Precise measurement of such kinematics is technically challenging. Biplane fluoroscopy is ideally suited to measure bone motion. Such systems have been developed in the past for both radiographic stereo-photogrammetric analysis (RSA) [1] and the more challenging model-based analysis [2]. Research groups have studied the knee [3,4], shoulder [5] and ankle [6] motion with similar techniques. The work presented here is an initial evaluation of the performance of our system, i.e., a validation that this in-house system can detect magnitudes of motion on-par with other existing systems.

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