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1

Diffraction phenomena inside thick Fresnel zone plates  

Microsoft Academic Search

The parabolic wave equation method is used to describe the complex wave field inside the body of a thick zone plate used to focus X ray radiation. Two analytical approaches are applied: (1) Diffraction of a plane wave incident onto a separate interface between opaque and open zones is considered. We construct an approximate analytical solution to the classical problem

Yuri V. Kopylov; Alexei V. Popov; Alexander V. Vinogradov

1996-01-01

2

Effect of plate thickness on stress state at sharp notches and the strength paradox of thick plates  

Microsoft Academic Search

Notched plates are often found in various applications ranging from microelectronic devices to large-scale civil structures. Stress analysis of plate components wherein the loading is uniformly distributed over the thickness, parallel to the plane of the plate, is normally based on plane stress or plane strain assumptions. Three-dimensional effects, such as the influence of the plate thickness on stress components,

Andrei Kotousov

2010-01-01

3

A mixed 3D finite element for modelling thick plates  

NASA Astrophysics Data System (ADS)

Based on the Hellinger-Reissner variational principle, we formulate a mixed 3-d finite element for plate bending. This element is used to model thick plates and alleviates the problem of shear-locking in plates with large length/thickness ratios. The computer code which was used here, is available.

Asch, Mark; Bercovier, Michel

1994-09-01

4

Plane impact of metal plates of equal thickness  

Microsoft Academic Search

The authors consider the problem of the collision of two metal plates of identical thickness l at velocity vâ in a vacuum and in the presence of an intervening layer of air of thickness lâ. They assume that the length of the plates is much greater than their thicknesses and accordingly study the wave interaction process in the one-dimensional approximation.

A. A. Deribas; V. M. Fomin; E. M. Khakimov; I. D. Zakharenko

1984-01-01

5

Standardization of Thick Crowberry Extract  

Microsoft Academic Search

Recently [1], we have developed a method for obtaining a thick extract of black crowberry (Empetrum nigrum L.) using an acetone infusion – a by-product in the technology of the anticonvulsant drug empetrin, also manufactured in this plant. The results of pharmacological tests performed in the Research Institute of Pharmacology (Tomsk Scientific Center, Siberian Division, Russian Academy of Medical Sciences,

E. V. Ermilova; T. V. Kadyrova; E. A. Krasnov; A. A. Blinnikova

2002-01-01

6

Plate Thickness Variation Effects on Crack Growth Rates in 7050-T7451 Alloy Thick Plate  

NASA Astrophysics Data System (ADS)

A study has been accomplished to characterize the fatigue crack growth rates and mechanisms in thick plate (16.51 cm) commercial grade 7050-T7451 aluminum plate in the L-S orientation. Examination of the effects of potential property gradients in the plate material was accomplished through hardness measurements along the short transverse direction and with compact tension tests. Tests exhibited a distinct trend of reduced center plane hardness in the plates. Compact tension specimens and the compliance method were used to determine crack growth rates for specimens machined from the t/4 and t/2 planar locations and oriented for L-S crack growth. Crack growth rate data (long crack) from the tests highlighted significant growth rate differences between the t/4 and t/2 locations. No significant effect of R-ratio was observed in the 0.05-0.3 range tested. Additionally, crack front splitting was noted in all specimens to differing degrees with data showing significant retardation of growth rate curves for the L-S orientation above 13 MPa ?m in the center plane, and 10 MPa ?m at quarter plane, where branching and splitting parallel to the load axis are dominant growth mechanisms.

Schubbe, Joel J.

2011-02-01

7

Oblique Perforation of Thick Metallic Plates by Rigid Projectiles  

Microsoft Academic Search

Oblique perforation of thick metallic plates by rigid projectiles with various nose shapes is studied in this paper. Two perforation mechanisms, i.e., the hole enlargement for a sharp projectile nose and the plugging formation for a blunt projectile nose, are considered in the proposed analytical model. It is shown that the perforation of a thick plate is dominated by several

Xiaowei Chen; Qingming Li; Saucheong Fan

2006-01-01

8

TRANSIENT THERMOELASTIC DEFORMATIONS OF A THICK FUNCTIONALLY GRADED PLATE  

Microsoft Academic Search

We study transient thermoelastic deformations of a thick functionally graded plate with edges held at a uniform temperature and either simply supported or clamped. Either the temperature or the heat flux is prescribed on the top surface of the plate with the bottom surface of the plate kept at either a uniform temperature or thermally insulated. Stresses and deformations induced

L. F. Qian; R. C. Batra

2004-01-01

9

Thickness vibration of an electroelastic plate under biasing fields.  

PubMed

We study thickness vibrations of an electroelastic plate under uniform but otherwise arbitrary thermoelectromechanical biasing fields in a manner more general than previous studies of thickness vibrations of plates. An exact solution is obtained for materials with general anisotropy. Special attention is paid to the case of thickness-shear vibrations of plates of monoclinic crystals. The special cases of unidirectional extension and free thermal expansion are discussed in detail. Simple and useful formulas for frequency shifts and capacitance change versus biasing fields are obtained. PMID:18019259

Yang, Jiashi

2007-10-01

10

Effect of the Plate Thickness on the Out-of-Plane Displacement Field of a Cracked Elastic Plate Loaded in Mode I  

Microsoft Academic Search

The paper presents analytical results on the out-of-plane displacement of the lateral surface of a plate in the vicinity of\\u000a a through-the-thickness crack at different ratios of the crack length to the plate thickness. The theoretical approach is\\u000a based on a recently developed three-dimensional elastic solution for an edge dislocation in a plate of arbitrary thickness\\u000a and the standard distributed

Andrei Kotousov; Peng Jing Tan

2004-01-01

11

Effect of Plate Thickness on Crack-Tip Plasticity  

Microsoft Academic Search

This paper presents an analytical method for determining the three-dimensional stress fields in plates with a through-the-thickness crack, especially under elastic-plastic conditions. Using the generalised plane strain theory in conjunction with the deformation theories of plasticity, exact solutions are obtained for the effects of plate thickness on the crack-tip plastic zone size and a plastic constraint factor, which is shown

A. Kotousov; C. H. Wang

2001-01-01

12

CTOD for the through-the-thickness crack in a plate of arbitrary thickness  

Microsoft Academic Search

The sectional thickness of plate-like components has a significant influence on the fatigue and fracture properties. This effect is primarily due to the differences in the through-the-thickness stresses prevailing at the tip of a crack in a finite-thickness plate or shell. Characterization of this effect to date has remained largely empirical. The current paper presents new analytical results for CTOD

Andrei Kotousov

2003-01-01

13

Transient motion of thick anisotropic plates  

NASA Technical Reports Server (NTRS)

Analyses are developed for the response of anisotropic plate strips to a transient load. The load is taken in the form of a line load of normal stress on the surface or within the body of the strip. The characteristic free vibrational modes of the strip are derived and used to derive the secular equation for this case in closed form and to isolate the mathematical conditions for symmetric and antisymmetric wave mode propagation in completely separate terms. The applied loads are expanded in terms of these normal modes and the response of the plate is obtained by superposition of the appropriate components. Material systems of higher symmetry are contained implicitly in the analysis.

Nayfeh, Adnan H.; Taylor, Timothy W.

1991-01-01

14

Modelling ultrasound guided wave propagation for plate thickness measurement  

NASA Astrophysics Data System (ADS)

Structural Health monitoring refers to monitoring the health of plate-like walls of large reactors, pipelines and other structures in terms of corrosion detection and thickness estimation. The objective of this work is modeling the ultrasonic guided waves generated in a plate. The piezoelectric is excited by an input pulse to generate ultrasonic guided lamb waves in the plate that are received by another piezoelectric transducer. In contrast with existing methods, we develop a mathematical model of the direct component of the signal (DCS) recorded at the terminals of the piezoelectric transducer. The DCS model uses maximum likelihood technique to estimate the different parameters, namely the time delay of the signal due to the transducer delay and amplitude scaling of all the lamb wave modes due to attenuation, while taking into account the received signal spreading in time due to dispersion. The maximum likelihood estimate minimizes the energy difference between the experimental and the DCS model-generated signal. We demonstrate that the DCS model matches closely with experimentally recorded signals and show it can be used to estimate thickness of the plate. The main idea of the thickness estimation algorithm is to generate a bank of DCS model-generated signals, each corresponding to a different thickness of the plate and then find the closest match among these signals to the received signal, resulting in an estimate of the thickness of the plate. Therefore our approach provides a complementary suite of analytics to the existing thickness monitoring approaches.

Malladi, Rakesh; Dabak, Anand; Murthy, Nitish Krishna

2014-03-01

15

Lamb waves and nearly-longitudinal waves in thick plates  

Microsoft Academic Search

We discuss waves created in relatively thick plates by edge excitation at frequency-thickness (fd) products that correspond, in principle, to multiple Lamb wave modes. For relatively low values of the fd product it is clear that Lamb wave modes will be generated, while at large values of the fd product we observe a bulk (longitudinal wave) in the solid, but

David W. Greve; Irving J. Oppenheim; Peng Zheng

2008-01-01

16

Lamb Waves and Nearly-Longitudinal Waves in Thick Plates  

Microsoft Academic Search

We discuss waves created in relatively thick plates by edge excitation at frequency-thickness (fd) products that correspond, in principle, to multiple Lamb wave modes. For relatively low values of the fd product it is clear that Lamb wave modes will be generated, while at large values of the fd product we observe a bulk (longitudinal wave) in the solid, but

David W. Greve; Irving J. Oppenheim; Peng Zheng

17

A new method for detecting lithium plating by measuring the cell thickness  

NASA Astrophysics Data System (ADS)

Charging Li-ion cells at low temperatures and/or high currents can cause the lithium ions to deposit on the anode surface rather than intercalating into the graphite lattice. This effect, named lithium plating, may severely affect the performance, reliability and safety of the cell. Because metallic lithium at the anode consumes more space than intercalated into the graphite, the cell volume increases in the case of lithium plating. An experimental setup for precise measuring the thickness of pouch cells with a resolution of 1 ?m was built. The cell thickness as a function of its charge under standard cycling conditions was recorded as a reference. In the case of lithium plating an additional increase of the thickness was observed. This can be used as an indicator for the non-destructive detection of lithium plating in pouch cells. Compared with the standard capacity based methods this procedure allows a higher sensitivity and gives results more quickly.

Bitzer, Bernhard; Gruhle, Andreas

2014-09-01

18

Oblique Perforation of Thick Metallic Plates by Rigid Projectiles  

NASA Astrophysics Data System (ADS)

Oblique perforation of thick metallic plates by rigid projectiles with various nose shapes is studied in this paper. Two perforation mechanisms, i.e., the hole enlargement for a sharp projectile nose and the plugging formation for a blunt projectile nose, are considered in the proposed analytical model. It is shown that the perforation of a thick plate is dominated by several non-dimensional numbers, i.e., the impact function, the geometry function of projectile, the non-dimensional thickness of target and the impact obliquity. Explicit formulae are obtained to predict the ballistic limit, residual velocity and directional change for the oblique perforation of thick metallic plates. The proposed model is able to predict the critical condition for the occurrence of ricochet. The proposed model is validated by comparing the predictions with other existing models and independent experimental data.

Chen, Xiaowei; Li, Qingming; Fan, Saucheong

2006-08-01

19

Exact vibration analysis of variable thickness thick annular isotropic and FGM plates  

Microsoft Academic Search

Annular plates are used in many engineering structures. In many cases variable thickness is used in order to save weight and improve structural characteristics. In recent years functionally graded materials (FGM) are used in many engineering applications. A FGM plate is an inhomogeneous composite made of two constituents (usually ceramic and metal), with both the composition and the material properties

E. Efraim; M. Eisenberger

2007-01-01

20

3D thermoelasticity solutions for functionally graded thick plates  

Microsoft Academic Search

Thermal-mechanical behavior of functionally graded thick plates, with one pair of opposite edges simply supported, is investigated\\u000a based on 3D thermoelasticity. As for the arbitrary boundary conditions, a semi-analytical solution is presented via a hybrid\\u000a approach combining the state space method and the technique of differential quadrature. The temperature field in the plate\\u000a is determined according to the steady-state 3D

Ji Ying; Chao-feng Lü; C. W. Lim

2009-01-01

21

Propagation of thickness-twist waves in elastic plates with periodically varying thickness and phononic crystals.  

PubMed

We study the propagation of thickness-twist (TT) waves in a crystal plate of AT-cut quartz with periodically varying, piecewise constant thickness. The scalar differential equation by Tiersten and Smythe is employed. The problem is found to be mathematically equivalent to the motion of an electron in a periodic potential field governed by Schrodinger's equation. An analytical solution is obtained. Numerical results show that the eigenvalue (frequency) spectrum of the waves has a band structure with allowed and forbidden bands. Therefore, for TT waves, plates with periodically varying thickness can be considered as phononic crystals. The effects of various parameters on the frequency spectrum are examined. PMID:24924785

Zhu, Jun; Chen, Weiqiu; Yang, Jiashi

2014-09-01

22

Perforation of a thick plate by rigid projectiles  

Microsoft Academic Search

Perforation of a thick plate by rigid projectiles with various geometrical characteristics is studied in the present paper. The rigid projectile is subjected to the resistant force from the surrounding medium, which is formulated by the dynamic cavity expansion theory. Two perforation mechanisms, i.e., the hole enlargement for a sharp projectile nose and the plugging formation for a blunt projectile

X. W. Chen; Q. M. Li

2003-01-01

23

Analytical 3-D p-element for quadrilateral plates—Part 1: Thick isotropic plate structures  

NASA Astrophysics Data System (ADS)

An analytical three-dimensional (3-D) p-version element for the vibration analysis of arbitrary quadrilateral thick plates is presented. With the additional hierarchical shape functions and analytically integrated element matrices, the computed accuracy is considerably improved. The computed natural frequencies of cantilever and simply supported square plates show that the convergence rate of the present element is very fast with respect to the number of hierarchical terms and it can predict very accurate modes. The element is applicable to the free vibration analysis of quadrilateral, polygonal plates as well as 3-D space structures. The continuous wavelet transform (CWT) is applied for the identification of damping ratios. Based on the Rayleigh damping model, the damped vibration response is obtained. A simple experiment is performed to verify the predicted vibration responses. The results show that the proposed element is also efficient for the vibration response analysis of plates.

Zhu, B.; Leung, A. Y. T.; Li, Q. S.; Lu, J. W. Z.; Zhang, X. C.

2007-06-01

24

Effect of base plate thickness on wave size and wave morphology in explosively welded couples  

Microsoft Academic Search

The influence of plate thickness on the wave morphology generated in explosive welding is analysed by the use of mild steel base plates machined into steps of different thicknesses and a constant-thickness mild steel flyer plate, to ensure similar impacting conditions. It is found that wave shape, at the same distance from the collision point, remains unchanged for the different

D. Jaramillov; O. T. Inal; A. Szecket

1987-01-01

25

Analysis of a Thick Dichroic Plate with Arbitrarily Shaped Holes  

NASA Astrophysics Data System (ADS)

A thick dichroic plate acts as a frequency selective surface (FSS) in that it is transparent at one frequency while at the same time reflective to other frequencies. It is used in the DSN to enable simultaneous multiple-frequency operation. Most of the plates currently in use were designed with programs that analyzed only the simple geometries, such as circular or rectangular holes. Since it is too expensive to experimentally determine the FSS parameters, only designs that could be accurately analyzed were chosen, and it is the primary reason why the recent FSS designs use rectangular holes. To achieve the sharp corners of the rectangular holes, it was necessary to use an electrical discharge machining (EDM) manufacturing technique. This manufacturing technique is expensive, and an important use of the arbitrary-shaped analysis is to enable designs that use rounded corners that are able to be manufactured by less expensive techniques. The analysis is accomplished by combining the finite-element method (FEM) for determining the waveguide modes of arbitrarily shaped guides with the method of moments and Floquet mode theory for periodic structures. The software was verified by comparison with previously measured and computed dichroic plates.

Imbriale, W. A.

2001-04-01

26

49 CFR 179.400-8 - Thickness of plates.  

Code of Federal Regulations, 2013 CFR

...in inches; S = minimum tensile strength of the plate material, as...in inches; S = minimum tensile strength of the plate material, as...in inches; S = minimum tensile strength of plate material, as...

2013-10-01

27

LOCAL BUCKLING ANALYSIS OF THICK ANISTROPIC PLATES USING COMPLEX FINITE STRIP METHOD  

Microsoft Academic Search

An analysis of buckling for thick anisotropic plates subjected to arbitrary loading is presented. The analysis employs the complex finite strip method which utilizes complex harmonic functions in the longitudinal direction, a cubic polynomial in the transverse direction and a parabolic distribution of the transverse shear strains through the thickness of the thick plate based on the higher-order shear deformation

M. AZHARI; K. H. KASSAEI

28

Estimates of elastic plate thicknesses beneath large volcanos on Venus  

NASA Technical Reports Server (NTRS)

Megellan radar imaging and topography data are now available for a number of volcanos on Venus greater than 100 km in radius. These data can be examined to reveal evidence of the flexural response of the lithosphere to the volcanic load. On Earth, flexure beneath large hotspot volcanos results in an annual topographic moat that is partially to completely filled in by sedimentation and mass wasting from the volcano's flanks. On Venus, erosion and sediment deposition are considered to be negligible at the resolution of Magellan images. Thus, it may be possible to observe evidence of flexure by the ponding of recent volcanic flows in the moat. We also might expect to find topographic signals from unfilled moats surrounding large volcanos on Venus, although these signals may be partially obscured by regional topography. Also, in the absence of sedimentation, tectonic evidence of deformation around large volcanos should be evident except where buried by very young flows. We use analytic solutions in axisymmetric geometry for deflections and stresses resulting from loading of a plate overlying an inviscid fluid. Solutions for a set of disk loads are superimposed to obtain a solution for a conical volcano. The deflection of the lithosphere produces an annular depression or moat, the extent of which can be estimated by measuring the distance from the volcano's edge to the first zero crossing or to the peak of the flexural arch. Magellan altimetry data records (ARCDRs) from data cycle 1 are processed using the GMT mapping and graphics software to produce topographic contour maps of the volcanos. We then take topographic profiles that cut across the annular and ponded flows seen on the radar images. By comparing the locations of these flows to the predicted moat locations from a range of models, we estimate the elastic plate thickness that best fits the observations, together with the uncertainty in that estimate.

Mcgovern, Patrick J.; Solomon, Sean C.

1992-01-01

29

49 CFR 179.220-6 - Thickness of plates.  

Code of Federal Regulations, 2013 CFR

...required bursting pressure in psig; S = Minimum tensile strength of plate material in p.s.i. as prescribed in...required bursting pressure in psig; S = Minimum tensile strength of plate material in psi as prescribed in AAR...

2013-10-01

30

Thermal buckling of a simply supported moderately thick rectangular FGM plate  

Microsoft Academic Search

Equilibrium and stability equations of a moderately thick rectangular plate made of functionally graded materials under thermal loads are derived based on the first order shear deformation theory. It is assumed that the material properties vary as a power form of thickness coordinate variable z. The derived equilibrium and buckling equations are then solved analytically for a plate with simply

Wu Lanhe

2004-01-01

31

Laser-Assisted Stir Welding of 25-mm-Thick HSLA65 Plate  

Microsoft Academic Search

Laser-assisted stir welding is a hybrid process that combines energy from a laser with functional heating and mechanical energy to join materials in the solid state. The technology is an adaptation of friction stir welding which is particularly suited for joining thick plates. Aluminum plates up to 75 mm thick have been successfully joined using friction stir welding. Since joining

Keith M. Williamson

2002-01-01

32

Three-Dimensional Vibration Analysis of Thick FGM Plate Strips Under Moving Line Loads  

Microsoft Academic Search

An exact three-dimensional analysis for steady-state dynamic response of an arbitrarily thick, isotropic, and functionally graded plate strip due to the action of a transverse distributed moving line load which is propagating parallel to the infinite simply supported edges of the plate at constant speed is presented based on the linear elasticity theory. The inhomogeneous plate is approximated by a

Seyyed M. Hasheminejad; Ahmad Rafsanjani

2009-01-01

33

Measurement of the residual stress distribution in a thick pre-stretched aluminum plate  

NASA Astrophysics Data System (ADS)

Thick pre-stretched aluminum alloy plates are widely used in aircraft, while machining distortion caused by initial residual stress release in thick plates is a common and serious problem. To reduce the distortion, the residual stress distribution in thick plate must be measured. According to the characteristics of the thick pre-stretched aluminum alloy plate, based the elastic mechanical theory, this article deduces the modified layer-removal strain method adapting two different strain situations, which are caused by tensile and compressive stress. To validate this method, the residual stresses distribution along the thick direction of plate 2D70T351 is measured by this method, it is shown that the new method deduced in this paper is simple and accurate, and is very useful in engineering.

Yuan, S. X.; Li, X. Q.; M, S.; Zhang, Y. C.; Gong, Y. D.

2008-12-01

34

On the Effect of Plate Thickness on Post-Overload Fatigue Crack Growth  

Microsoft Academic Search

Plate thickness can have a profound effect on fatigue crack growth following theapplication of an overload cycle. A modified\\u000a strip-yield model is presented for determining the effects of plate thickness based on the mechanism of plasticity-induced\\u000a crack closure and first-order plate theory. This approach eliminates the need for any empirical or fitting parameters. Comparisons\\u000a are made with experimental data for

John Codrington

2009-01-01

35

Buccal Bone Plate Thickness of the Asian People  

Microsoft Academic Search

Distances from the apex to the buccal bone plate were measured on the computed tomography (CT) images of 1806 teeth from 66 patients, using an image analyzer program (Image-Pro Plus, Ver. 4.0, Media Cybernetics). In the mandible, the mean distance from the distal apex of the mandibular second molar to the buccal bone plate was the largest distance measured, at

G.-C Jin; K.-D Kim; B.-D Roh; C.-Y Lee; S.-J Lee

2005-01-01

36

Free vibration of stepped thickness rectangular plates using spectral finite element method  

NASA Astrophysics Data System (ADS)

Free vibration of stepped thickness rectangular plates is investigated in this paper using the spectral finite element method (SFEM). It is impossible to obtain closed-form solutions for a uniform rectangular plate with arbitrary boundary conditions except the Levy-type plates, i.e., at least simply-supported at two opposite edges. Moreover, the variation of plate thickness adds complexity to the problem. The Kantorovich method is employed to obtain an analytical approximation solution form. Then, a plate spectral finite element is developed accordingly in the frequency domain. Similar to the conventional finite element method (CFEM), after assembling elements and applying boundary conditions, each modal frequency and associated mode shape function can be determined by iteratively solving corresponding equations in plate x and y directions. Available literature results along with NASTRAN simulations are used to validate our SFEM predictions of stepped thickness plates with various boundary conditions. Compared to the CFEM, only a fraction of the mesh is needed to achieve comparable accuracy in each mode. Substantial computation cost can then be saved. Mode shape functions are extracted and presented in a semi-analytical form. Physical insights of wave propagation characteristics in a stepped thickness rectangular plate can be collected from these results. In summary, an efficient and accurate SFEM is developed to conduct free vibration analysis of stepped thickness rectangular plates with various boundary conditions. Assume the mnth plate mode shape function with a separation of variables form W(x,y,?)=?i=1NxX(x,?)Yn(y,?)={

Wang, Gang; Unal, Ahmet

2013-09-01

37

49 CFR 179.300-6 - Thickness of plates.  

Code of Federal Regulations, 2013 CFR

...pressure in psig; S = minimum tensile strength of plate material in p.s...are clad with material having tensile strength at least equal to the base...cladding material does not have tensile strength at least equal to the...

2013-10-01

38

A simple method to measure the thickness and order number of a wave plate  

NASA Astrophysics Data System (ADS)

Thickness and order number are important parameters for a wave plate in optical experiments. However, the encapsulation of the wave plate makes its thickness difficult to measure directly. In this paper, we propose an indirect measurement method to obtain the thickness and order number of a uniaxial crystal wave plate. With this method only the maximum and minimum values of the optical power of the transmitted light through the wave plate are measured in the experiment by rotating the wave plate around its optical axis. This simple method is easy to realize in the college physics laboratory, and it is also of importance for students to further understand the underlying physics of the wave plates.

Hu, Yichuan; Yi, Zhenglei; Yang, Hujiang; Xiao, Jinghua

2013-09-01

39

Thickness vibrations of a piezo-semiconducting plate layer  

Microsoft Academic Search

The small thickness oscillations of a piezo-semiconducting planar layer of finite thickness including heat conduction effects are investigated. On the surfaces of the structure, certain (homogeneous) boundary conditions are prescribed. Basically, the excitation can be either a mechanical body force, a volume-distributed heat source or a prescribed charge production inside the slab. A linear description and the usual electrically quasistatic

S. Suherman

1997-01-01

40

New approach to the excitation of plate waves for piezoelectric thick-film devices.  

PubMed

A method is presented for exciting the propagation of plate waves in elastic guides. It is implemented in a device whose minimum working structure consists of a non-piezoelectric plane guide and two piezoelectric transducers operating as a generator and detector. The device is entirely in accordance with thick-film technology standard procedures. Both transducers are composed of a PZT ferroelectric layer deposited on a ceramic substrate and a suitable system of three coplanar metal electrodes placed inside the same layer. Beside setting the wavelength of propagation, the electrode system promotes piezoelectric deformations parallel to the substrate simultaneously contracting and extending contiguous active regions in the layer. Pure shear stresses are then induced on the involved guide surface, alternately distributed, with the spatial periodicity of the wave that will propagate in the guide. The propagation of several kinds of guided waves is possible so the selection of the one that meets a specific device design best is allowed. This work describes the design, realization and operation of a prototype structure consisting of an alumina plate guide and two pairs of piezoelectric thick-film transducers realized on it. The results related to the propagation of symmetric and asymmetric Lamb modes are reported. Moreover, the potential of the method is highlighted, emphasizing its effectiveness, easy implementation and application in the development of devices for the sensing and non-destructive testing areas. PMID:18486958

De Cicco, Giorgio; Morten, Bruno

2008-12-01

41

Effects of Thickness and Ply Orientation on Buckling of Laminated Plates.  

National Technical Information Service (NTIS)

The buckling loads of laminated plates are predicted using a new theory which takes into account transverse shearing effects. This new theory assumes trigonometric terms through-the-thickness in the displacements to take into account transverse shearing e...

D. C. Jegley

1986-01-01

42

Effects of Thickness and Ply Orientation on Buckling of Laminated Plates.  

National Technical Information Service (NTIS)

The buckling loads of laminated plates are predicted using a new theory which takes into account transverse shearing ettects. This new theory assumes trigonometric terms through-the-thickness in the displacements to take into account transverse shearing e...

D. C. Jegley

1986-01-01

43

Programmed Test Method of Heavy Thickness Steel Plates for Nuclear Vessels.  

National Technical Information Service (NTIS)

The authors have developed a programmed test method which is capable of verifying the mechanical properties of heavy thickness steel plates for nuclear vessels by using small specimens which are simulated to the cooling curves from austenitized temperatur...

H. Susukida T. Ando Y. Hibaru

1971-01-01

44

Effect of mechanical restraint on weldability of reduced activation ferritic/martensitic steel thick plates  

NASA Astrophysics Data System (ADS)

As one of the reduced activation ferritic/martensitic steels, the weldability of thick F82H plate was experimentally examined using new heat sources in order to minimize the total heat input energy in comparison with TIG welding. A full penetration of 32 mm thick plate could be produced as a combination of a 12 mm deep first layer generated by a 10 kW fiber laser beam and upper layers deposited by a plasma MIG hybrid welding with Ar + 2%O shielding gas. Also, the effect of mechanical restraint on the weldability under EB welding of thick F82H plate was studied by using FEM to select an appropriate specimen size for the basic test. The appropriate and minimum size for the basic test of weldability under EB welding of 90 mm thick plate might be 200 mm in length and 400 mm in width where the welding length should be about 180 mm.

Serizawa, Hisashi; Nakamura, Shinichiro; Tanaka, Manabu; Kawahito, Yousuke; Tanigawa, Hiroyasu; Katayama, Seiji

2011-10-01

45

Vibration and Damping of Laminated, Composite-Material Plates Including Thickness-Shear Effects.  

National Technical Information Service (NTIS)

An analytical investigation of sinusoidally forced vibration of laminated, anisotropic plates including bending-stretching coupling, thbility, all three types of inertia effects, and material damping is presented. In the analysis the effects of thickness-...

C. C. Siu C. W. Bert

1972-01-01

46

Energy trapping of thickness-shear vibration modes of elastic plates with functionally graded materials.  

PubMed

Energy trapping has important applications in the design of thickness-shear resonators. Considerable efforts have been made for the effective utilization and improvement of energy trapping with variations of plate configurations, such as adding electrodes and contouring. As a new approach in seeking improved energy trapping feature, we analyze thickness-shear vibrations in an elastic plate with functionally graded material (FGM) of in-plane variation of mechanical properties, such as elastic constants and density. A simple and general equation governing the thickness-shear modes is derived from a variational analysis. A plate with piecewise constant material properties is analyzed as an example. It is shown that such a plate can support thickness-shear vibration modes with obvious energy trapping. Bechmann's number for the existence of only one trapped mode also can be determined accordingly. PMID:17375839

Wang, Ji; Yang, Jiashi; Li, Jiangyu

2007-03-01

47

A solution procedure for behavior of thick plates on a nonlinear foundation and postbuckling behavior of long plates  

NASA Technical Reports Server (NTRS)

Approximate solutions for three nonlinear orthotropic plate problems are presented: (1) a thick plate attached to a pad having nonlinear material properties which, in turn, is attached to a substructure which is then deformed; (2) a long plate loaded in inplane longitudinal compression beyond its buckling load; and (3) a long plate loaded in inplane shear beyond its buckling load. For all three problems, the two dimensional plate equations are reduced to one dimensional equations in the y-direction by using a one dimensional trigonometric approximation in the x-direction. Each problem uses different trigonometric terms. Solutions are obtained using an existing algorithm for simultaneous, first order, nonlinear, ordinary differential equations subject to two point boundary conditions. Ordinary differential equations are derived to determine the variable coefficients of the trigonometric terms.

Stein, M.; Stein, P. A.

1978-01-01

48

Three-dimensional elastic stress fields near notches in finite thickness plates  

Microsoft Academic Search

Based on detailed three-dimensional finite element (3D FE) analyses, elastic notch-root fields in plates with different thicknesses and notch configurations subjected to uniaxial tension have been investigated. By comparing with the planar notch-root fields and crack-tip fields, the following characteristics of the 3D stress–strain fields near the notch front are revealed: (1) The plate thickness and notch configuration have obvious

Zhenhuan Li; Wanlin Guo; Zhenbang Kuang

2000-01-01

49

The distributed dislocation technique for calculating plasticity-induced crack closure in plates of finite thickness  

Microsoft Academic Search

An analytical method for calculating plasticity-induced fatigue crack closure in plates of finite thickness is presented.\\u000a The developed method utilizes the distributed dislocation technique (DDT) and Gauss-Chebyshev quadrature. Crack tip plasticity\\u000a is incorporated by adopting a Dugdale type strip yield model. The finite plate thickness effects are taken into account by\\u000a using a recently obtained three-dimensional solution for an edge

John Codrington; Andrei Kotousov

2007-01-01

50

Meshless Local Petrov-Galerkin (MLPG) Formulation for Analysis of Thick Plates  

Microsoft Academic Search

An efficient meshless formulation based on the Local Petrov-Galerkin approach for the analysis of shear deformable thick plates is presented. Using the kinematics of a three-dimensional continuum, the local symmetric weak form of the equilibrium equations over the cylindrical shaped local sub-domain is derived. The linear test function in the plate thickness direction is as- sumed. Discretization in the in-plane

J. Sori ´; Q. Li; T. Jarak; S. N. Atluri

51

Convective Heat Transfer from a Thick Hemispherical Plate during Free Liquid Jet Impingement  

Microsoft Academic Search

Convective heat transfer during free liquid jet impingement on a hemispherical solid plate of finite thickness has been examined. The model included the entire fluid region (impinging jet and flow spreading out over the hemispherical surface) and solid plate as a conjugate problem. Solution was done for both isothermal and constant heat flux boundary conditions at the inner surface of

Muhammad M. Rahman; Jorge C. Lallave; Cesar F. Hernandez

2008-01-01

52

Inelastic local buckling of flat, thin-walled structures containing thickness-tapered plates  

Microsoft Academic Search

This paper is concerned with the inelastic local buckling of flat plate structures that contain plates with variable thicknesses. Use is made of the semi-analytical complex finite strip method, which is augmented with transverse bubble functions. Stiffness and stability matrices are derived for inclusion in the finite strip method, which is based on the deformation theory of plasticity. The numerical

M. Azhari; M. M. Saadatpour; M. A. Bradford

2004-01-01

53

A finite difference method at arbitrary meshes for the bending of plates with variable thickness  

Microsoft Academic Search

A finite difference method at arbitrary meshes for the bending of plates with variable thickness is presented in this paper.\\u000a The method is completely general with respect to various boundary conditions, load cases and shapes of plates. This difference\\u000a scheme is simple and the numerical results agree well with those obtained by other methods.

Li Guang-yao; Zhou Han-bin

1993-01-01

54

Aluminum-Copper-Lithium Alloy 2050 Developed for Medium to Thick Plate  

Microsoft Academic Search

This article discusses Al-Cu-Li 2050 alloy developed, qualified, and produced by Alcan Aerospace as plates. AA2050 alloy offers\\u000a a low density high corrosion resistant alternative to incumbent medium to thick plate alloys like 7050-T7451, and to thin\\u000a plate alloys like 2024 or higher damage tolerant versions. The fundamentals behind the choice of the Al-Cu-Li chemistry are\\u000a highlighted, as well as

Ph. Lequeu; K. P. Smith; A. Daniélou

2010-01-01

55

Measurement of water falling film thickness to flat plate using confocal chromatic sensoring technique  

SciTech Connect

An experimental investigation of wavy water film falling down a flat plate has been carried out using confocal chromatic sensoring technique to determine the instantaneous and statistical characteristics of the film. The experiments involved three parameters: liquid feed mode, Reynolds number and plate inclination angle. The present time-average film thickness data is compared with the previous experimental and theoretical results showing a good agreement. A new correlation for the average film thickness is suggested. Our results show that the liquid feed mode has a vital influence on the film thickness and that the film thickness increases with Reynolds number and decreased plate inclination angle. The root-mean-square value of the film thickness fluctuations depends non-monotonically on the film Reynolds number. The corresponding mechanisms are analyzed. (author)

Zhou, D.W. [Darmstadt University of Technology, Chair of Technical Thermodynamics Petersenstr. 30, 64287 Darmstadt (Germany)]|[Department of Mechanical and Aerospace Engineering, Arizona State University, Tempe, AZ 85287-6106 (United States); Gambaryan-Roisman, T.; Stephan, P. [Darmstadt University of Technology, Chair of Technical Thermodynamics Petersenstr. 30, 64287 Darmstadt (Germany)

2009-01-15

56

Orientation anomalies in plating thickness measurements from advanced packaging substrates  

NASA Astrophysics Data System (ADS)

Experiments show that serious anomalies arise in the measurement by XRF of film thickness in bond fingers on packages. The anomalies can be exposed as a package orientation dependence in the film thickness measurement. The orientation anomalies occur on translation of the specimen between rows of bond fingers. The anomalies are due to either primary fluorescence or to scattered radiation from the substrate with an escape path to the detector. In bond fingers consisting of Au, Ni and Cu, primary fluorescence of substrate Br enhances the Au signal, while scattering of W characteristic lines enhances the Ni signal. The anomalies can be overcome by ensuring that the bond finger lies in the plane containing the x-ray source and the proportional counter detector so that substrate emissions are buried. Instrumental improvements are also suggested.

Tan, N. X.; Lee, A. J. Y.; Bourdillon, A. J.; Tan, C. Y. S.

1996-03-01

57

Vibration and damping of laminated, composite-material plates including thickness-shear effects  

NASA Technical Reports Server (NTRS)

An analytical investigation of sinusoidally forced vibration of laminated, anisotropic plates including bending-stretching coupling, thickness-shear flexibility, all three types of inertia effects, and material damping is presented. In the analysis the effects of thickness-shear deformation are considered by the use of a shear correction factor K, analogous to that used by Mindlin for homogeneous plates. Two entirely different approaches for calculating the thickness-shear factor for a laminate are presented. Numerical examples indicate that the value of K depends on the layer properties and the stacking sequence of the laminate.

Bert, C. W.; Siu, C. C.

1972-01-01

58

Damage assessment and residual compression strength of thick composite plates with through-the-thickness reinforcements  

NASA Technical Reports Server (NTRS)

Damage in composite materials was studied with through-the-thickness reinforcements. As a first step it was necessary to develop new ultrasonic imaging technology to better assess internal damage of the composite. A useful ultrasonic imaging technique was successfully developed to assess the internal damage of composite panels. The ultrasonic technique accurately determines the size of the internal damage. It was found that the ultrasonic imaging technique was better able to assess the damage in composite panel with through-the-thickness reinforcements than by destructively sectioning the specimen and visual inspection under a microscope. Five composite compression-after-impact panels were tested. The compression-after-impact strength of the panels with the through-the-thickness reinforcements was almost twice that of the comparable panel without through-the-thickness reinforcement.

Smith, Barry T.; Farley, Gary L.; Maiden, Janice; Coogan, Dreux; Moore, Judith G.

1991-01-01

59

Damage assessment and residual compression strength of thick composite plates with through-the-thickness reinforcements  

NASA Technical Reports Server (NTRS)

Damage in composite materials was studied with through-the-thickness reinforcements. As a first step it was necessary to develop new ultrasonic imaging technology to better assess internal damage of the composite. A useful ultrasonic imaging technique was successfully developed to assess the internal damage of composite panels. The ultrasonic technique accurately determines the size of the internal damage. It was found that the ultrasonic imaging technique was better able to assess the damage in a composite panel with through-the-thickness reinforcements than by destructively sectioning the specimen and visual inspection under a microscope. Five composite compression-after-impact panels were tested. The compression-after-impact strength of the panels with the through-the-thickness reinforcements was almost twice that of the comparable panel without through-the-thickness reinforcement.

Smith, Barry T.

1990-01-01

60

Characterization of Fracture and Fatigue Behavior of 7050 Aluminum Alloy Ultra-thick Plate  

NASA Astrophysics Data System (ADS)

The microstructure, mechanical property, fracture toughness, and fatigue behavior of 7050 aluminum alloy pre-stretched ultra-thick plate were investigated by means of optical microscopy, scanning electron microscopy, transmission electron microscopy, tensile test, fracture toughness test, and high-cycle fatigue test. The results showed that the microstructure of the ultra-thick plate consisted of recrystallized grains, subgrains, constituent particles, precipitated phases, and precipitate-free zone. Mechanical tests indicated that anisotropy of fracture toughness existed in L-T, T-L, and S-T orientation. Fractographic features suggested that this anisotropy was significant due to the difference of recrystallized grain on different metallographic planes. Compared to 7050 aluminum alloy plate in less thickness, the ultra-thick plate showed deterioration on fracture toughness due to the increase of recrystallized grains but improvement on fatigue property ascribed to the less densely populated particles. Fractographic observations showed that fatigue initiation of this ultra-thick plate was primarily related to the constituent particles and promoted by increase of the stress amplitude.

Wei, Lili; Pan, Qinglin; Wang, Yilin; Feng, Lei; Huang, Hongfeng

2013-09-01

61

Orbiter Cold Plate Intergranular Corrosion: Development of NDE Standards and Assessment of NDE Methods  

NASA Technical Reports Server (NTRS)

During pre-servicing of a space shuttle (orbiter vehicle, OV-102), helium leak detection of an avionics cold plate identified a leak located in the face sheet oriented towards the support shelf. Subsequent destructive examination of the leaking cold plate revealed that intergranular corrosion had penetrated the 0.017-inch thick aluminum (AA6061) face sheet. The intergranular attack (IGA) was likely caused by an aggressive crevice environment created by condensation of water vapor between the cold plate and support shelf. Face sheet susceptibility to IGA is a result of the brazing process used in the fabrication of the cold plates. Cold plate components were brazed at 1000 F followed by a slow cooling process to avoid distortion of the bonded cold plate. The slow cool process caused excessive grain boundary precipitation resulting in a material that is susceptible to IGA. The objectives of this work are as follows: (1) Develop first-of-a-kind nondestructive evaluation (NDE) standards that contain IGA identical to that found in the orbiter cold plates; and (2) Assess advanced NDE techniques for corrosion detection and recommend methods for cold plate examination. This report documents the results of work performed at Langley Research Center to fulfill these objectives.

Smith, Stephen W.; Winfree, William P.; Piascik, Robert S.

2002-01-01

62

Propagating plane harmonic waves through finite length plates of variable thickness using finite element techniques  

NASA Technical Reports Server (NTRS)

An analysis is given using finite element techniques which addresses the propagaton of a uniform incident pressure wave through a finite diameter axisymmetric tapered plate immersed in a fluid. The approach utilized in developing a finite element solution to this problem is based upon a technique for axisymmetric fluid structure interaction problems. The problem addressed is that of a 10 inch diameter axisymmetric fixed plate totally immersed in a fluid. The plate increases in thickness from approximately 0.01 inches thick at the center to 0.421 inches thick at a radius of 5 inches. Against each face of the tapered plate a cylindrical fluid volume was represented extending five wavelengths off the plate in the axial direction. The outer boundary of the fluid and plate regions were represented as a rigid encasement cylinder as was nearly the case in the physical problem. The primary objective of the analysis is to determine the form of the transmitted pressure distribution on the downstream side of the plate.

Clark, J. H.; Kalinowski, A. J.; Wagner, C. A.

1983-01-01

63

Development of Eddy Current Probe for Thick-Walled Plates and Quantitative Evaluation of Cracks  

NASA Astrophysics Data System (ADS)

This paper demonstrates the crack detection of thick-walled non-magnetic metal plates by eddy current testing, which used to be difficult because of the skin effect generally. For the purpose, this paper proposes a novel eddy current testing probe for cracks in thick-walled plates and evaluates the capability of the present probe. The probe was designed, based on the numerical computation using 3D fast eddy current code. The advantages of the present probe are strong eddy current on the back of specimens and small decay of eddy current in the thickness direction. Through experiments, we confirmed that this probe can detect the back artificial defect on INCONEL718 specimen with thickness of 7.0mm and 304 Stainless steel specimen with thickness of 8.0mm.

Takagi, T.; Uchimoto, T.; Sato, K.; Huang, H.

2003-03-01

64

Thickness effects on the plastic collapse of perforated plates with triangular penetration patterns  

SciTech Connect

This paper investigates the effects of plate thickness on the accuracy of limit load solutions obtained using an elastic-perfectly plastic [EPP] equivalent solid [EQS] procedure for flat perforated plates with a triangular array of penetrations. The EQS approach for limit loads is based on an EQS collapse surface that is valid for generalized plane strain. This assumption is applicable for very thick plates but is known to be less reasonable for very thin plates where plane stress may be a better assumption. The limits of applicability of the generalized plane strain assumption are investigated by obtaining limit load solutions for perforated plates of various thicknesses that are subjected to in-plane and bending loads. Plastic limit load solutions obtained using three-dimensional EPP finite element analysis [FEA] of models which include each penetration explicitly are compared with solutions obtained using the EQS approximation. The penetration pattern chosen for this study has a ligament efficiency (ligament width-to-pitch ratio, h/P) of 0.32. For plates thicker than the pitch, the limit load calculated using the EQS method for both in-plane and bending loads is shown to be very accurate (within 4%) of the limit load calculated for the explicit model. On the other hand, for thin plates (t/P< 2), the EQS limit load is 5% greater than the explicit limit load for bending and 8% greater than the explicit limit load for in-plane loads. For thinner plates, the collapse surface is tied to the local geometry deformation and, hence, an equivalent solid plate representation of plastic collapse is a function of deformation mode and thickness.

Gordon, J.L.; Jones, D.P.; Holliday, J.E.

2000-03-01

65

A study on friction stir welding of 12mm thick aluminum alloy plates  

NASA Astrophysics Data System (ADS)

Most of the investigations regarding friction stir welding (FSW) of aluminum alloy plates have been limited to about 5 to 6 mm thick plates. In prior work conducted the various aspects concerning the process parameters and the FSW tool geometry were studied utilizing friction stir welding of 12 mm thick commercial grade aluminum alloy. Two different simple-to-manufacture tool geometries were used. The effect of varying welding parameters and dwell time of FSW tool on mechanical properties and weld quality was examined. It was observed that in order to achieve a defect free welding on such thick aluminum alloy plates, tool having trapezoidal pin geometry was suitable. Adequate tensile strength and ductility can be achieved utilizing a combination of high tool rotational speed of about 2000 r/min and low speed of welding around 28 mm/min. At very low and high dwell time the ductility of welded joints are reduced significantly.

Kumar, Deepati Anil; Biswas, Pankaj; Tikader, Sujoy; Mahapatra, M. M.; Mandal, N. R.

2013-12-01

66

Experimentation and modeling of inclined ballistic impact in thick polycarbonate plates  

Microsoft Academic Search

The penetration and perforation of a thick polycarbonate (PC) plate (one and 3 stacked) by an armor piercing 7.62 mm projectile is investigated experimentally and numerically. The characteristic structure of the projectile’s trajectory in the PC plates is studied. It is observed that the trajectory consist of a cavity and a circumferential cracked zone attached to it, which is fully embedded

A. Dorogoy; D. Rittel; A. Brill

2011-01-01

67

Effect of projectile nose shape, impact velocity and target thickness on deformation behavior of aluminum plates  

Microsoft Academic Search

The present study deals with the experimental and numerical investigations of aluminum target plates impacted by blunt, ogive and hemispherical nosed steel projectiles. The projectiles were normally impacted on the target plates of 0.5, 0.71, 1, 1.5, 2, 2.5 and 3mm thicknesses at different velocities with the help of a pneumatic gun. Effect of projectile nose shape, impact velocity and

N. K. Gupta; M. A. Iqbal; G. S. Sekhon

2007-01-01

68

Crack-growth behavior in thick welded plates of Inconel 718 at room and cryogenic temperatures  

NASA Technical Reports Server (NTRS)

Results of mechanical-properties and axial-load fatigue and fracture tests performed on thick welded plates of Inconel 718 superalloy are presented. The test objectives were to determine the tensile strength properties and the crack-growth behavior in electron-beam, plasma-arc, and gas tungsten are welds for plates 1.90 cm (0.75 in) thick. Base-metal specimens were also tested to determine the flaw-growth behavior. The tests were performed in room-temperature-air and liquid nitrogen environments. The experimental crack-growth-rate data are correlated with theoretical crack-growth-rate predictions for semielliptical surface flaws.

Forman, R. G.

1974-01-01

69

Relation between subduction megathrust earthquakes, sediment thickness at trench, and plate coupling  

NASA Astrophysics Data System (ADS)

Extreme seismic events (Mw 8.5 and higher) are uniformly characterized by trench-parallel rupture lengths longer than about 250 km, whereas downdip rupture width ranges from less than 70 km (e.g., Central Aleutians) to more than 200 km (e.g., Andaman-Sumatra). The ability of rupture to propagate in the trench-parallel direction thus appears to play a fundamental role in determining the potential magnitude that an earthquake can achieve for a given subduction zone. The rupture length may be influenced by the nature of the plate interface and the normal stresses applied to the plate interface (plate coupling). The nature of the plate interface is potentially modified by sediment subduction. Subduction of a thick section of trench sediment constructs a laterally homogenous layer between upper and lower plates that smoothes subducted sea-floor relief and strength-coupling asperities (Ruff, 1989). Such a homogeneous interface running parallel to the subduction zone tends to favor long trench-parallel propagation of rupture, and thus large earthquake magnitudes. Compressive normal stresses applied along the plate interface may also tune the earthquake magnitude potential (Ruff & Kanamori, 1980). This plate coupling across the subducting interface can be indirectly estimated by Upper Plate Strain analysis, by using the back-arc as a strain sensor from which we can infer the back-arc stress state. Compressive back-arcs indicate that large stresses are transmitted across the plate interface whereas extensional settings indicate weak plate coupling. Here we present the results of a study funded by the European Science Foundation - EURYI project titled "Convergent margin and seismogenesis". Maximal earthquake magnitude, sediment thickness at the trench and Upper Plate Strain are characterized for worldwide subduction zones in order to test how plate coupling and sediment thickness combine to explain the occurrence of mega-events at the subduction interface. Subduction zones are described through an initial set of 505 transects, systematically extracted each 1° of trench, and merged into 62 subduction segments of homogeneous seismogenetic conditions. Maximal earthquake magnitude has been estimated by combining instrumental and historical seismicity. Trench sediment thickness has been constrained for 48 subduction segments; based on a compilation of 165 different seismic-reflection lines (33% of the initial set of transects).

Heuret, A.; Conrad, C. P.; Funiciello, F.; Lallemand, S.

2011-12-01

70

Thickness-twist and face-shear waves in piezoelectric plates of monoclinic crystals.  

PubMed

We study the propagation of thickness-twist and face-shear waves in piezoelectric plates of monoclinic crystals, which include rotated Y-cut quartz and langasite as special cases. The equations of linear piezoelectricity are used. Exact solutions are obtained for both fully-electroded and unelectroded plates. Dispersion relations are plotted for both AT-cut quartz and Y-cut langasite plates. The difference in frequencies between the exact piezoelectric solutions obtained in the present paper and the approximate elastic solutions in the literature is found to be of the order of 1%, which is significant in acoustic wave resonator and sensor applications. PMID:23443714

Zhu, Jun; Chen, Weiqiu

2011-12-01

71

On the relations between cratonic lithosphere thickness, plate motions, and basal drag  

USGS Publications Warehouse

An overview of seismic, thermal, and petrological evidence on the structure of Precambrian lithosphere suggests that its local maximum thickness is highly variable (140-350 km), with a bimodal distribution for Archean cratons (200-220 km and 300-350 km). We discuss the origin of such large differences in lithospheric thickness, and propose that the lithospheric base can have large depth variations over short distances. The topography of Bryce Canyon (western USA) is proposed as an inverted analog of the base of the lithosphere. The horizontal and vertical dimensions of Archean cratons are strongly correlated: larger cratons have thicker lithosphere. Analysis of the bimodal distribution of lithospheric thickness in Archean cratons shows that the "critical" surface area for cratons to have thick (>300 km) keels is >6-8 ?? 106 km2 . Extrapolation of the linear trend between Archean lithospheric thickness and cratonic area to zero area yields a thickness of 180 km. This implies that the reworking of Archean crust should be accompanied by thinning and reworking of the entire lithospheric column to a thickness of 180 km in accord with thickness estimates for Proterozoic lithosphere. Likewise, extrapolation of the same trend to the size equal to the total area of all Archean cratons implies that the lithospheric thickness of a hypothesized early Archean supercontinent could have been 350-450 km decreasing to 280-400 km for Gondwanaland. We evaluate the basal drag model as a possible mechanism that may thin the cratonic lithosphere. Inverse correlations are found between lithospheric thickness and (a) fractional subduction length and (b) the effective ridge length. In agreement with theoretical predictions, lithospheric thickness of Archean keels is proportional to the square root of the ratio of the craton length (along the direction of plate motion) to the plate velocity. Large cratons with thick keels and low plate velocities are less eroded by basal drag than small fast-moving cratons. Basal drag may have varied in magnitude over the past 4 Ga. Higher mantle temperatures in the Archean would have resulted in lower mantle viscosity. This in turn would have reduced basal drag and basal erosion, and promoted the preservation of thick (>300 km) Archean keels, even if plate velocities were high during the Archean. ?? 2002 Elsevier Science B.V. All rights reserved.

Artemieva, I. M.; Mooney, W. D.

2002-01-01

72

A phenomenological model for perforation of moderately thick plates by tumbling projectiles  

Microsoft Academic Search

A phenomenological model has been developed to describe the mechanism of tumbling perforation of blunt-faced cylindrical projectiles in moderately thick aluminum plates. The perforation process, based on experimental observations, consists of four stages: erosion; plugging; hole enlargement and petaling. The modeling in the plugging stage consists sequentially of cratering, plug formation, plug separation, plug slipping and post perforation deformation. Bulging

Kezhun Li; Werner Goldsmith

1996-01-01

73

A Higher Order Shear Deformation Theory for the Vibration of Thick Plates  

Microsoft Academic Search

Several first order, shear deformation theories for thick plates have been formulated during the past half-century (e.g., by Reissner, Hencky, Mindlin and Ambartsumyan). The Mindlin theory has been widely used for vibration analysis. It is well known that consideration of shear flexibility corrects the flexural frequencies by reducing them. However, it has been found that first order shear deformation theories

N. F. Hanna; A. W. Leissa

1994-01-01

74

Effect of target thickness in blunt projectile penetration of Weldox 460 E steel plates  

Microsoft Academic Search

This paper describes an experimental, analytical and numerical investigation of the penetration and perforation of circular Weldox 460 E steel plates with different thicknesses struck by a blunt projectile at various impact velocities. In the experimental tests, a compressed gas gun was used to launch the sabot mounted projectile at impact velocities well above and just below the ballistic limit

Tore Børvik; Odd Sture Hopperstad; Magnus Langseth; Kjell Arne Malo

2003-01-01

75

Thermal optimization of plate-fin heat sinks with fins of variable thickness under natural convection  

Microsoft Academic Search

In this study, thermal performance of a vertical plate-fin heat sink under natural convection was optimized for the case in which the fin thickness varied in the direction normal to the fluid flow. For this optimization, the averaging approach presented in an earlier paper for the case of the heat sinks under forced convection was extended to study the performance

Dong-Kwon Kim

76

The finite element analysis of thickness-shear vibrations of quartz crystal plates with ANSYS  

Microsoft Academic Search

Finite element analysis is a powerful approach to the vibration analysis of complicated structures including the piezoelectric acoustic wave resonators such as the quartz crystal resonators, which usually vibrate at the thickness-hear mode with much higher frequency. The analysis has been done with the Mindlin plate equations for straight-crested wave solutions for displacements and vibration frequency, which are important in

Ji Wang; Jun Shi; Jian-ke Du

2009-01-01

77

Fineline photoprocessing of thick resists for solar-cell and hybrid-circuit plating applications  

SciTech Connect

Several types of photoresist candidates were evaluated for solar cells and thin film networks. Candidates included wet and dry film, positive and negative acting, and solvent and aqueous types. After development work to produce high resolution patterns in thick resist with vertical sidewalls, two candidates for pattern plating were examined. (LEW)

Norwood, D.

1983-01-01

78

Comparison of Thin Plate and Thick Aerofoil Blades in a Centrifugal Fan.  

National Technical Information Service (NTIS)

The patterns and stability of the airflow in the rotor of a centrifugal fan have been studied, with thin plate blading and with thick aerofoil blades. Specifications of the blading are presented, and a detailed comparison is made of the visualised flow pa...

H. S. Fowler

1971-01-01

79

Non-destructive thickness measurement of dichromated gelatin films deposited on glass plates  

Microsoft Academic Search

A quick estimation of the thickness of thin films deposited on glass plates is described in this paper. The principle of the method is based on the measurement of the Haidinger fringes generated by the film. For ease of observation and measurement, a commercial Fizeau-type interferometer such as a Zygo interferometer using a large angle of illumination has been used.

R. P. Shukla; D. V. Udupa; N. C. Das; Murty V. Mantravadi

2006-01-01

80

Thick shell tectonics on one-plate planets - Applications to Mars  

Microsoft Academic Search

Using the zero frequency equations of a self-gravitating elastic spherical shell overlying a strengthless fluid, a theory for stress distribution in thick lithospheric shells on one-plate planets is developed. For both the compensated and flexural modes, stress distributions in lithospheres are reviewed. For compensated modes, surface stresses depend only on surface topography, whereas for flexural modes it is shown that,

W. B. Banerdt; R. S. Saunders; R. J. Phillips; N. H. Sleep

1982-01-01

81

Aluminum-Copper-Lithium Alloy 2050 Developed for Medium to Thick Plate  

NASA Astrophysics Data System (ADS)

This article discusses Al-Cu-Li 2050 alloy developed, qualified, and produced by Alcan Aerospace as plates. AA2050 alloy offers a low density high corrosion resistant alternative to incumbent medium to thick plate alloys like 7050-T7451, and to thin plate alloys like 2024 or higher damage tolerant versions. The fundamentals behind the choice of the Al-Cu-Li chemistry are highlighted, as well as the property balance generated in a wide range of thickness from 12 to 127 mm (0.5 to 5 in.). Manufacturing behavior of the alloy when machining or friction stir welding is also discussed in detail. Finally, it is shown that the appropriate recycling investments and logistics permit the use of 2050 alloy at an acceptable level of extra cost per kilo saved, when weight benefits are taken into account.

Lequeu, Ph.; Smith, K. P.; Daniélou, A.

2010-08-01

82

Relation between subduction megathrust earthquakes, trench sediment thickness and upper plate strain  

NASA Astrophysics Data System (ADS)

Giant earthquake (moment magnitude Mw ? 8.5) forecasts for subduction zones have been empirically related to both tectonic stresses and geometrical irregularities along the subduction interface. Both of these controls have been suggested as able to tune the ability of rupture to propagate laterally and, in turn, exert an important control on giant earthquake generation. Here we test these hypotheses, and their combined influence, by compiling a dataset of trench fill thickness (a proxy for smoothing of subducting plate relief by sediment input into the subduction channel) and upper plate strain (a proxy for the tectonic stresses applied to the subduction interface) for 44 segments of the global subduction network. We statistically compare relationships between upper plate strain, trench sediment thickness and maximal earthquake magnitude. We find that the combination of both large trench fill (?1 km) and neutral upper plate strain explains spatial patterns of giant earthquake occurrence to a statistically significant degree. In fact, the concert of these two factors is more highly correlated with giant earthquake occurrence than either factor on its own. Less frequent giant earthquakes of lower magnitude are also possible at subduction zones with thinner trench fill and compressive upper plate strain. Extensional upper plate strain and trench fill < 0.5 km appear to be unfavorable conditions, as giant earthquakes have not been observed in these geodynamical environments during the last 111 years.

Heuret, A.; Conrad, C. P.; Funiciello, F.; Lallemand, S.; Sandri, L.

2012-03-01

83

Thickness measurement system for transparent plates using dual digital versatile disc (DVD) pickups  

SciTech Connect

A low-cost high-precision thickness measurement system for transparent plates that uses dual digital versatile disc (DVD) pickups is proposed. The two DVD pickups are used as the transmitter and the receiver in the measurement system, respectively. One of the DVD pickups emits a laser to the other DVD pickup (receiver) and projects on the photodiode integrated circuit of the receiver. The transparent plate is placed in the optical path to change the focused point that will affect the focusing error signal (FES) of the receiver. Using the FES, a mathematical model for thickness measurement based on the geometric optical method is developed. The experimental results show that the accuracy is 1.5 {mu}m, and the uncertainty is estimated to be {+-}1.37 {mu}m for the measured thickness of 150{mu}m.

Liu, Chien-Hung; Yeh, Shien-Chang; Huang, Hsueh-Liang

2010-02-01

84

Testing Plate Reconstructions For The High Arctic Using Crustal Thickness Mapping From Gravity Inversion  

NASA Astrophysics Data System (ADS)

The plate tectonic history of the Amerasia Basin (High Arctic) and its distribution of oceanic and continental lithosphere is poorly known. A new method of gravity inversion with an embedded lithosphere thermal gravity anomaly correction has been applied to the NGA (U) Arctic Gravity Project data to predict crustal thickness and to test different plate reconstructions within the Arctic region. Two end member plate reconstruction models have been tested: in one model the Mendeleev Ridge is rifted from the Canadian margin while in the other it is rifted from the Lomonosov Ridge. The inversion of gravity data to map crustal thickness variation within oceanic and rifted continental margin lithosphere requires the incorporation of a lithosphere thermal gravity anomaly correction for both oceanic and continental lithosphere. Oceanic lithosphere and stretched continental margin lithosphere produce a large negative residual thermal gravity anomaly (up to -380 mGal), for which a correction must be made in order to determine realistic Moho depth by gravity anomaly inversion. The lithosphere thermal model used to predict the lithosphere thermal gravity anomaly correction may be conditioned using plate reconstruction models to provide the age and location of oceanic lithosphere. Two end- member plate reconstruction models have been constructed for the opening of the Amerasia Basin and used to determine lithosphere thermal gravity anomaly corrections: in one model the (presumably) continental Mendeleev Ridge is rifted from the Canadian margin in the Jurassic while in the other it is rifted off the Lomonosov Ridge (Eurasia Basin) in the Late-Cretaceous. Crustal thickness predicted by gravity anomaly inversion for the two plate reconstructions is significantly different in the Makarov Basin because of their different lithosphere thermal gravity corrections. The plate reconstruction with younger Makarov Basin ages gives a crustal thickness of the order 6-8 km thinner than the older Makarov Basin model. A crustal thickness of approximately 20 km has been obtained from seismic refraction data (Lebedeva-Ivanova et al., 2006) which would imply a Late Mid-Cretaceous age for the Makarov Basin. In this case plume-related forces may have contributed to the opening of this basin, as regional plate tectonics predict compression and not extension in the Makarov Basin area at this time.

Alvey, A. D.; Gaina, C.; Kusznir, N. J.; Torsvik, T. H.

2006-12-01

85

Postbuckling response of long thick plates loaded in compression including higher order transverse shearing effects  

NASA Technical Reports Server (NTRS)

Buckling and postbuckling results are presented for compression-loaded simply-supported aluminum plates and composite plates with a symmetric lay-up of thin + or - 45 deg plies composed of many layers. Buckling results for aluminum plates of finite length are given for various length-to-width ratios. Asymptotes to the curves based on buckling results give N(sub xcr) for plates of infinite length. Postbuckling results for plates with transverse shearing flexibility are compared to results from classical theory for various width-to-thickness ratios. Characteristic curves indicating the average longitudinal direct stress resultant as a function of the applied displacements are calculated based on four different theories: Classical von Karman theory using the Kirchoff assumptions, first-order shear deformation theory, higher-order shear deformation theory, and 3-D flexibility theory. Present results indicate that the 3-D flexibility theory gives the lowest buckling loads. The higher-order shear deformation theory has fewer unknowns than the 3-D flexibility theory but does not take into account through-the-thickness effects. The figures presented show that small differences occur in the average longitudinal direct stress resultants from the four theories that are functions of applied end-shortening displacement.

Stein, Manuel; Sydow, P. Daniel; Librescu, Liviu

1990-01-01

86

Postbuckling response of long thick plates loaded in compression including higher order transverse shearing effects  

NASA Technical Reports Server (NTRS)

This paper presents buckling and postbuckling results for compression-loaded simply-supported aluminum plates and composite plates with a symmetric lay-up of thin +/-45-deg plies composed of many layers. Buckling results for aluminum plates of finite length are given for various length-to-width ratios. Asymptotes to the curves based on the buckling results give N(XCr) for plates of infinite length. Postbuckling results for plates with transverse shearing flexibility are compared to results from classical theory for various width-to-thickness ratios. Characteristic curves indicating the average longitudinal direct stress resultant as a function of the applied displacements are calculated based on four different theories: classical von Karman theory using the Kirchhoff assumptions, first-order shear deformation theory, higher-order shear deformation theory, and three-dimensional flexibility theory. Present results indicate that the three-dimensional flexibility theory gives the lowest buckling loads. The higher-order shear deformation theory has fewer unknowns than the three-dimensional flexibility theory but does not take into account through-the-thickness effects. The figures presented show that small differences occur in the average longitudinal direct stress resultants from the four theories that are functions of applied end-shortening displacement.

Stein, Manuel; Sydow, Daniel P.; Librescu, Liviu

1990-01-01

87

An equivalent single-layer approach for free vibration analysis of smart laminated thick composite plates  

NASA Astrophysics Data System (ADS)

An equivalent single-layer model for the free vibration analysis of smart laminated plates is presented. The electric and magnetic fields are assumed to be quasi-static, and third order in-plane kinematics is employed to adequately take the shear influence into account when the plate thickness increases. The model governing equations are the plate equations of motion written in terms of mechanical primary variables and effective stiffness coefficients, which take the multi-field coupling effects into account. The model shows that the surface magneto-electric boundary conditions enter the definitions of the laminate forces and moment resultants. Moreover, it reveals that new stiffness terms, which are related to the derivatives of the transverse displacement component and are exclusively associated with the piezoelectric and piezomagnetic couplings, are involved. Free vibration solutions for simply supported plates are presented to validate the model by comparing the present results with benchmark 3D solutions. Comparison of the results obtained by lower order models, namely zero and first order shear deformation theories, is presented and discussed, focusing on the adequateness of the obtained models with respect to the plate thickness. Some characteristic features of smart laminate behavior have also been addressed.

Milazzo, A.; Orlando, C.

2012-07-01

88

Evaluation of Palatal Plate Thickness of Maxillary Prosthesis on Phonation- A Comparative Clinical Study  

PubMed Central

Background: Prosthodontic treatment involves clinical procedures which influence speech performance directly or indirectly. Prosthetic rehabilitation of missing teeth with partial or complete maxillary removable dentures influences the individual voice characteristics like Phonation, resonance etc. Aim: To evaluate the effect of Acrylic palatal plate thickness (1mm-3mm) of maxillary prosthesis on phonation. Materials and Methods: Twelve subjects were selected randomly between the age group of 20-25 years who have full complement of teeth and have no speech problems. Speech evaluation was done under four experimental conditions i.e. Without any experimental acrylic palatal plate (control), with experimental acrylic palatal plates of thickness 1 mm, 2 mm and 3 mm respectively. The speech material for phonation test consisted of Vowels sounds /a/, /i/, and /o/. Speech analysis to assess phonation was done using digital acoustic analysis (PRAAT software). The obtained results were statistically analyzed by One-way ANOVA and Tukey’s multiple post-hoc for comparison of four experimental conditions with respect to different vowel sounds. Results: Mean harmonics to noise ratio (HNR) values obtained for all the Experimental conditions did not show significant difference (p>0.05). In conclusion, an increase in the thickness of the acrylic palatal plate of maxillary prosthesis for about 1 mm - 3mm in complete or partial maxillary removable dentures resulted in no significant effect on phonation of vowel sounds /a/, /i/ and /o/. Conclusion: Increasing the thickness of the palatal plate from 1 mm to 3 mm has not shown any significant effect on the phonation.

B, Sreedevi; Anne, Gopinadh; Manne, Prakash; Bindu O, Swetha Hima; Atla, Jyothi; Deepthi, Sneha; Chaitanya A, Krishna

2014-01-01

89

Contribution of antisymmetric and symmetric waves to the reflection of sound in a fluid by a thick, homogeneous plate  

Microsoft Academic Search

Thick-plate theory, for flexural and extensional waves in plates is applied to the analysis of the reflection of sound from an isotropic, homogeneous plate. An explicit expression is given for the reflection coefficient when both antisymmetric and symmetric waves are contributing to the reflection mechanism. This is compared with the case in which these types of waves are assumed to

P. S. Dubbelday

1980-01-01

90

An equilibrium method for prediction of transverse shear stresses in a thick laminated plate  

NASA Technical Reports Server (NTRS)

First two equations of equilibrium are utilized to compute the transverse shear stress variation through thickness of a thick laminated plate after in-plane stresses have been computed using an assumed quadratic displacement triangular element based on transverse inextensibility and layerwise constant shear angle theory (LCST). Centroid of the triangle is the point of exceptional accuracy for transverse shear stresses. Numerical results indicate close agreement with elasticity theory. An interesting comparison between the present theory and that based on assumed stress hybrid finite element approach suggests that the latter does not satisfy the condition of free normal traction at the edge. Comparison with numerical results obtained by using constant shear angle theory suggests that LCST is close to the elasticity solution while the CST is closer to classical (CLT) solution. It is also demonstrated that the reduced integration gives faster convergence when the present theory is applied to a thin plate.

Chaudhuri, R. Z.

1986-01-01

91

Nonlinear theory for laminated and thick plates and shells including the effects of transverse shearing  

NASA Technical Reports Server (NTRS)

Nonlinear strain displacement relations for three-dimensional elasticity are determined in orthogonal curvilinear coordinates. To develop a two-dimensional theory, the displacements are expressed by trigonometric series representation through-the-thickness. The nonlinear strain-displacement relations are expanded into series which contain all first and second degree terms. In the series for the displacements only the first few terms are retained. Insertion of the expansions into the three-dimensional virtual work expression leads to nonlinear equations of equilibrium for laminated and thick plates and shells that include the effects of transverse shearing. Equations of equilibrium and buckling equations are derived for flat plates and cylindrical shells. The shell equations reduce to conventional transverse shearing shell equations when the effects of the trigonometric terms are omitted and to classical shell equations when the trigonometric terms are omitted and the shell is assumed to be thin.

Stein, M.

1985-01-01

92

Accurate free vibration analysis of thick laminated circular plates with attached rigid core  

NASA Astrophysics Data System (ADS)

This paper deals with the free vibration behavior of laminated transversely isotropic circular plates with axisymmetric rigid core attached at the center. The governing equations of motion are obtained based on Mindlin's first-order shear deformation plate theory. Two possible categories of vibration modes related to up-down translation of the core and wobbly rotation of the core about a diameter are studied. Accurate natural frequencies hitherto not reported in the literature are presented for a wide range of thickness-to-radius ratio, inner-to-outer radius ratio, mass and moment of inertia ratios of the core and various boundary conditions at the outer edge of the plate. Numerical results are compared with those of a three-dimensional finite element method (3-D FEM) to demonstrate the high accuracy and reliability of the current analysis.

Hosseini-Hashemi, Sh.; Rezaee, V.; Atashipour, S. R.; Girhammar, U. A.

2012-12-01

93

Mechanical response of thick laminated beams and plates subject to out-of-plane loading  

NASA Technical Reports Server (NTRS)

The use of simplified elasticity solutions to determine the mechanical response of thick laminated beams and plates subject to out-of-plane loading is demonstrated. Excellent results were obtained which compare favorably with theoretical, numerical and experimental analyses from other sources. The most important characteristic of the solution methodology presented is that it combines great mathematical precision with simplicity. This symbiosis has been needed for design with advanced composite materials.

Hiel, C. C.; Brinson, . F.

1989-01-01

94

Non-destructive thickness measurement of dichromated gelatin films deposited on glass plates  

NASA Astrophysics Data System (ADS)

A quick estimation of the thickness of thin films deposited on glass plates is described in this paper. The principle of the method is based on the measurement of the Haidinger fringes generated by the film. For ease of observation and measurement, a commercial Fizeau-type interferometer such as a Zygo interferometer using a large angle of illumination has been used. The simple modification to observe the Haidinger fringes with the Fizeau-type interferometer is also described. The thickness of the film is related to the diameters of the Haidinger fringes. It is possible to estimate the thickness quickly by counting the number of fringes. A more accurate estimate can be obtained by the measurement of the diameters of the fringes and using these data in a formula that relates these two to the thickness of the film. The method is found to be useful for measuring the thickness of dichromated gelatin films (DCG) coated on a substrate to make holographic optical elements. The accuracy in estimating the thickness of the film is of the order ±1 ?m. The method is entirely non-destructive and works well in the thickness range of 5- 150 ?m.

Shukla, R. P.; Udupa, D. V.; Das, N. C.; Mantravadi, Murty V.

2006-10-01

95

Postbuckling response of long thick isotropic plates loaded in compression including higher order transverse shearing effects  

NASA Technical Reports Server (NTRS)

Buckling and postbuckling results for aluminum plates loaded in compression are presented. The buckling results were plotted to show the effects of thickness on the stress coefficient. Buckling results are given for various length-to-width ratios. Postbuckling results for plates with transverse shearing flexibility are compared to results from classical theory for various width-to-thickness ratios. The plates are considered to be long with side edges simply supported, with edges free of stress and the plates are subjected to longitudinal compressive displacement. Characteristic curves indicating the average longitudinal direct stress resultant as a function of the applied displacements are calculated based on four different theories: Classical von Karman, first-order shear deformation, higher-order shear deformation, and three-dimensional flexibility. Present results indicate that the three-dimensional flexibility theory gives the lowest and therefore, most accurate results. The higher-order shear deformation theory has fewer unknowns than the three-dimensional flexibility but is not as accurate. The figures presented show that small differences occur in the maximum stress resultants and the transverse displacements calculated when the effects of transverse shear are included.

Stein, Manuel; Sydow, P. Daniel; Librescu, Liviu

1990-01-01

96

Three-Dimensional transient heat conduction in a functionally graded thick plate with a higher-order plate theory and a meshless local Petrov-Galerkin method  

NASA Astrophysics Data System (ADS)

We analyze transient heat conduction in a thick functionally graded plate by using a higher-order plate theory and a meshless local Petrov-Galerkin (MLPG) method. The temperature field is expanded in the thickness direction by using Legendre polynomials as basis functions. For temperature prescribed on one or both major surfaces of the plate, modified Lagrange polynomials are used as basis and additional terms are added to these expansions to exactly match the given temperatures. Partial differential equations for the evolution of the coefficients of the Legendre polynomials are reduced to a set of coupled ordinary differential equations (ODEs) in time by a MLPG method. The ODEs are integrated by the central-difference method. The time history of evolution of the temperature at the plate centroid and through-the-thickness distribution of the temperature computed with the fifth-order plate theory are found to agree very well with those obtained analytically.

Qian, L. F.; Batra, R. C.

2005-02-01

97

Single Transducer Ultrasonic Imaging Method that Eliminates the Effect of Plate Thickness Variation in the Image  

NASA Technical Reports Server (NTRS)

This article describes a single transducer ultrasonic imaging method that eliminates the effect of plate thickness variation in the image. The method thus isolates ultrasonic variations due to material microstructure. The use of this method can result in significant cost savings because the ultrasonic image can be interpreted correctly without the need for machining to achieve precise thickness uniformity during nondestructive evaluations of material development. The method is based on measurement of ultrasonic velocity. Images obtained using the thickness-independent methodology are compared with conventional velocity and c-scan echo peak amplitude images for monolithic ceramic (silicon nitride), metal matrix composite and polymer matrix composite materials. It was found that the thickness-independent ultrasonic images reveal and quantify correctly areas of global microstructural (pore and fiber volume fraction) variation due to the elimination of thickness effects. The thickness-independent ultrasonic imaging method described in this article is currently being commercialized under a cooperative agreement between NASA Lewis Research Center and Sonix, Inc.

Roth, Don J.

1996-01-01

98

Analysis of thick plates by using a higher-order shear and normal deformable plate theory and MLPG method with radial basis functions  

Microsoft Academic Search

Infinitesimal deformations of a homogeneous and isotropic thick elastic plate have been analyzed by using a meshless local Petrov–Galerkin (MLPG) method and a higher-order shear and normal deformable plate theory (HONSDPT). Radial basis functions (RBF) are employed for constructing trial solutions, while a spline function is used as the weight function over a local subdomain. The present method uses a

J. R. Xiao; R. C. Batra; D. F. Gilhooley; J. W. Gillespie Jr; M. A. McCarthy

2007-01-01

99

Analysis of thick functionally graded plates by using higher-order shear and normal deformable plate theory and MLPG method with radial basis functions  

Microsoft Academic Search

Infinitesimal deformations of a functionally graded thick elastic plate are analyzed by using a meshless local Petrov–Galerkin (MLPG) method, and a higher-order shear and normal deformable plate theory (HOSNDPT). Two types of Radial basis functions RBFs, i.e. Multiquadrics and Thin Plate Splines, are employed for constructing the trial solutions, while a fourth-order Spline function is used as the weight\\/test function

D. F. Gilhooley; R. C. Batra; J. R. Xiao; M. A. McCarthy; J. W. Gillespie Jr

2007-01-01

100

Integrated crustal thickness mapping and plate reconstructions for the high Arctic  

NASA Astrophysics Data System (ADS)

The plate tectonic history of the Amerasia Basin (High Arctic) and its distribution of oceanic and continental lithosphere are poorly known. A new method of gravity inversion with an embedded lithosphere thermal gravity anomaly correction has been applied to the NGA (U) Arctic Gravity Project (ArcGP) data to predict crustal thickness and continental lithosphere thinning factors which are used to test different plate reconstructions within the Arctic region. The inversion of gravity data to map crustal thickness variation within oceanic and rifted continental margin lithosphere requires the incorporation of a lithosphere thermal gravity anomaly correction for both oceanic and continental lithosphere. Oceanic lithosphere and stretched continental margin lithosphere produce a large negative residual thermal gravity anomaly (up to - 380 mGal), for which a correction must be made in order to determine realistic Moho depth by gravity anomaly inversion. The lithosphere thermal model used to predict the lithosphere thermal gravity anomaly correction may be conditioned using plate reconstruction models to provide the age and location of oceanic lithosphere. Three plate reconstruction models have been examined for the opening of the Amerasia Basin, two end member models and a hybrid model: in one end member model the Mendeleev Ridge is rifted from the Canadian margin while in the other it is rifted from the Lomonosov Ridge (Eurasia Basin), the hybrid model contains elements of both end member models. The two end member plate reconstruction models are consistent with the gravity inversion for their prediction of the location of oceanic lithosphere within the Canada Basin but fail in the Makarov and Western Podvodnikov Basins. The hybrid model is consistent with predictions of the location of the ocean-continent transition from continental lithosphere thinning factors obtained from gravity inversion. A crustal thickness of approximately 20 km is predicted for Late Cretaceous Makarov/Podvodnikov Basins which is similar to the value obtained from seismic refraction. We suggest that this method could be used for discriminating between various plate tectonic scenarios, especially in remote or poorly surveyed regions.

Alvey, A.; Gaina, C.; Kusznir, N. J.; Torsvik, T. H.

2008-10-01

101

Effect of plastic cover thickness on top loss coefficient of flat-plate collectors  

SciTech Connect

The effect of plastic cover thickness on the top heat loss coefficient of collectors with outer glass and inner Teflon glazings is investigated. The total radiative properties of the Teflon films are computed from measured normal incidence spectral data. These properties are used in the overall heat transfer analysis of the system. Results are obtained for plastic thicknesses from 12.5 {mu}m to 100 {mu}m, over a range of wind heat loss coefficients and several absorber emissivities. These values are compared with those for collectors with glass covers and the difference is correlated with the important design variables. The results show that for low values of the absorber emissivity (e.g., those with selective coatings), the dependence of the loss coefficient on the film thickness is small. However, in the case of most frequently encountered collectors which have a high absorber plate emissivity, the thickness of the plastic cover can have a significant effect on the collector heat loss coefficient. This is true for the single-plastic cover and two-plastic cover systems. A design correlation for the top heat loss coefficient is presented in terms of the plastic cover thickness.

Wijeysundera, N.E. (National Univ. of Singapore (Singapore)); Iqbal, M. (Univ. of British Columbia, Vancouver, British Columbia (Canada))

1991-01-01

102

Measurement of relevant elastic and damping material properties in sandwich thick plates  

NASA Astrophysics Data System (ADS)

An easy-to-implement method to measure relevant elastic and damping properties of the constituents of a sandwich structure, possibly with a heterogeneous core, is proposed. The method makes use of a one-point dynamical measurement on a thick-plate. The hysteretic model for each (possibly orthotropic) constituent is written generically as " E(1+j?)" for all mechanical parameters. The estimation method of the parameters relies on a mixed experimental/numerical procedure. The frequencies and dampings of the natural modes of the plate are obtained from experimental impulse responses by means of a high-resolution modal analysis technique. This allows for considerably more experimental data to be used. Numerical modes (frequencies, dampings, and modal shapes) are computed by means of an extended Rayleigh-Ritz procedure under the "light damping" hypothesis, for given values of the mechanical parameters. Minimising the differences between the modal characteristics yields an estimation of the values of the mechanical parameters describing the hysteretic behaviour. A sensitivity analysis assesses the reliability of the method for each parameter. Validations of the method are proposed by (a) applying it to virtual plates on which a finite-element model replaces the experimental modal analysis, (b) some comparisons with results obtained by static mechanical measurements, and (c) by comparing the results on different plates made of the same sandwich material.

Rébillat, Marc; Boutillon, Xavier

2011-12-01

103

Three-dimensional static analysis of thick functionally graded plates by using meshless local Petrov–Galerkin (MLPG) method  

Microsoft Academic Search

In this paper, a version of meshless local Petrov–Galerkin (MLPG) method is developed to obtain three-dimensional (3D) static solutions for thick functionally graded (FG) plates. The Young's modulus is considered to be graded through the thickness of plates by an exponential function while the Poisson's ratio is assumed to be constant. The local symmetric weak formulation is derived using the

R. Vaghefi; G. H. Baradaran; H. Koohkan

2010-01-01

104

Effect of projectile nose shape, impact velocity and target thickness on the deformation behavior of layered plates  

Microsoft Academic Search

The present study is based on the experimental and numerical investigations of deformation behavior of layered aluminum plates of different thicknesses under the impact of flat, ogive and hemispherical nosed steel projectiles. Thin-layered plates arranged in various combinations were normally impacted at different velocities with the help of a pneumatic gun. Ballistic limit velocity and the residual velocity of the

N. K. Gupta; M. A. Iqbal; G. S. Sekhon

2008-01-01

105

Exact closed-form frequency equations for thick circular plates using a third-order shear deformation theory  

Microsoft Academic Search

This paper presents, for the first time, exact closed-form frequency equations and transverse displacement for thick circular plates with free, soft simply supported, hard simply supported and clamped boundary conditions based on Reddy's third-order shear deformation theory. Hamiltonian and minimum potential energy principles are used to extract the equations of dynamic equilibrium and natural boundary conditions of the plate. The

Sh. Hosseini-Hashemi; M. Es'Haghi; H. Rokni Damavandi Taher; M. Fadaie

2010-01-01

106

An improved plate theory of order (1,2) for thick composite laminates  

NASA Technical Reports Server (NTRS)

A new (1,2)-order theory is proposed for the linear elasto-static analysis of laminated composite plates. The basic assumptions are those concerning the distribution through the laminate thickness of the displacements, transverse shear strains and the transverse normal stress, with these quantities regarded as some weighted averages of their exact elasticity theory representations. The displacement expansions are linear for the inplane components and quadratic for the transverse component, whereas the transverse shear strains and transverse normal stress are respectively quadratic and cubic through the thickness. The main distinguishing feature of the theory is that all strain and stress components are expressed in terms of the assumed displacements prior to the application of a variational principle. This is accomplished by an a priori least-square compatibility requirement for the transverse strains and by requiring exact stress boundary conditions at the top and bottom plate surfaces. Equations of equilibrium and associated Poisson boundary conditions are derived from the virtual work principle. It is shown that the theory is particularly suited for finite element discretization as it requires simple C(sup 0)- and C(sup -1)-continuous displacement interpolation fields. Analytic solutions for the problem of cylindrical bending are derived and compared with the exact elasticity solutions and those of our earlier (1,2)-order theory based on the assumed displacements and transverse strains.

Tessler, A.

1992-01-01

107

A crack closure model of fatigue crack growth in plates of finite thickness under small-scale yielding conditions  

Microsoft Academic Search

Crack growth rates are significantly affected by the thickness of the specimen when all other parameters are kept constant. A quantitative estimation of the thickness effect is thus necessary to make predictions of crack growth rates more accurate and reliable. For this purpose a theoretical model was developed based on the strip-yield assumption and first-order plate theory. No empirical or

John Codrington; Andrei Kotousov

2009-01-01

108

Simple Method for Plating Escherichia coli Bacteriophages Forming Very Small Plaques or No Plaques under Standard Conditions ?  

PubMed Central

The use of low concentrations (optimally 2.5 to 3.5 ?g/ml, depending on top agar thickness) of ampicillin in the bottom agar of the plate allows for formation of highly visible plaques of bacteriophages which otherwise form extremely small plaques or no plaques on Escherichia coli lawns. Using this method, we were able to obtain plaques of newly isolated bacteriophages, propagated after induction of prophages present in six E. coli O157:H? strains which did not form plaques when standard plating procedures were employed.

Los, Joanna M.; Golec, Piotr; Wegrzyn, Grzegorz; Wegrzyn, Alicja; Los, Marcin

2008-01-01

109

Simple method for plating Escherichia coli bacteriophages forming very small plaques or no plaques under standard conditions.  

PubMed

The use of low concentrations (optimally 2.5 to 3.5 microg/ml, depending on top agar thickness) of ampicillin in the bottom agar of the plate allows for formation of highly visible plaques of bacteriophages which otherwise form extremely small plaques or no plaques on Escherichia coli lawns. Using this method, we were able to obtain plaques of newly isolated bacteriophages, propagated after induction of prophages present in six E. coli O157:H(-) strains which did not form plaques when standard plating procedures were employed. PMID:18586961

Lo?, Joanna M; Golec, Piotr; Wegrzyn, Grzegorz; Wegrzyn, Alicja; Lo?, Marcin

2008-08-01

110

Static Analysis of Thick Functionally Graded Plates by using a Higher-Order Shear and Normal Deformable Plate Theory and MLPG method with Radial Basis Functions  

Microsoft Academic Search

Infinitesimal deformations of a thick functionally graded elastic plate have been analyzed by using the meshless local Petrov-Galerkin\\u000a (MLPG) method and the higher-order shear and normal deformable plate theory (HOSNDPT). Radial basis functions (RBF) are employed\\u000a for constructing trial functions, while a spline function is used as the weighting function over a local subdomain. The present\\u000a method employs a number

Romesh C. Batra; Jia-Run Xiao; David F. Gilhooley; Michael A. McCarthy; John W. Gillespie

111

Elastostatic Deformations of a Thick Plate by using a Higher-Order Shear and Normal Deformable Plate Theory and two Meshless Local Petrov-Galerkin (MLPG) Methods  

Microsoft Academic Search

We use two meshless local Petrov-Galerkin formulations, namely, the MLPG1 and the MLPG5, to analyze infinitesimal deformations of a homogeneous and isotropic thick elastic plate with a higher-order shear and normal deformable plate theory. It is found that the two MLPG formulations give results very close to those obtained by other researchers and also by the three- dimensional analysis of

L. F. Qianl; R. C. Batra; L. M. Chen

112

The influence of Poisson’s ratio on thickness-dependent stress concentration at elliptic holes in elastic plates  

Microsoft Academic Search

The influence of Poisson’s ratio (?) on the thickness-dependent stress concentration factor (SCF) along the root of elliptic holes in elastic plates subjected to tension is systematically investigated by use of three-dimensional finite element method. It is found that the thickness-dependent maximum of SCF, (Kt)max, increases significantly with increasing ?. As the thickness to root radius ratio B\\/? grows from

Peishi Yu; Wanlin Guo; Chongmin She; Junhua Zhao

2008-01-01

113

Analysis of method for measuring thickness of plane-parallel plates and lenses using chromatic confocal sensor.  

PubMed

Noncontact optical metrology based on the chromatic confocal principle is becoming increasingly important for fast and accurate measurements of surface topography, distance, and layer thickness in engineering and industry. These sensors are based on the wavelength dependence of longitudinal chromatic aberration of optical systems, and the distance or thickness of the measured sample is coded into spectral information. We provide a theoretical analysis of a problem of the thickness measurement of transparent samples (glass plane-parallel plates or lenses) with respect to material dispersion. Our work deals with a description and analysis of induced measurement errors in the cases of measurement of the thickness of a plane-parallel plate and the central thickness of a lens. Relations are derived for a quantitative evaluation of these errors and a method is presented for minimizing the influence of these errors on the accuracy of measurement. PMID:20539342

Miks, Antonin; Novak, Jiri; Novak, Pavel

2010-06-10

114

78 FR 63015 - Exhaust Emissions Standards for New Aircraft Gas Turbine Engines and Identification Plate for...  

Federal Register 2010, 2011, 2012, 2013

...Emissions Standards for New Aircraft Gas Turbine Engines and Identification Plate for Aircraft...amended the emission standards for certain turbine engine powered airplanes to incorporate...The EPA also proposed adopting the gas turbine engine test procedures of the...

2013-10-23

115

78 FR 63017 - Exhaust Emissions Standards for New Aircraft Gas Turbine Engines and Identification Plate for...  

Federal Register 2010, 2011, 2012, 2013

...Emissions Standards for New Aircraft Gas Turbine Engines and Identification Plate for Aircraft...comments amending the emission standards for turbine engine powered airplanes to incorporate...The EPA also proposed adopting the gas turbine engine test procedures of the...

2013-10-23

116

Some Considerations Regarding Film Thickness Standards for the Semiconductor Industry.  

National Technical Information Service (NTIS)

The paper first considers some of the requisite properties of Standard Reference Materials (SRMs) for effective use in improving the uniformity of measurements. It then considers some of the limitations imposed by real-world thin film specimens and our st...

J. R. Ehrstein

1980-01-01

117

Properties of thick 5083-O aluminum alloy plates for the equatorial ring of a spherical LNG cargo tank  

SciTech Connect

The characteristics of a newly developed 160-mm thick 5083-O aluminum alloy plate have been examined with particular emphasis placed on the through thickness (ST) properties. Elongation of the plate in the ST direction is higher than for any other available in data. The fatigue properties are also satisfactory and fatigue strength in the ST direction is 11 kgf/mm/sup 2/ at 10/sup 7/ cycles. The deep notch test result demonstrates that the plate behaves in a fully ductile manner even with a load in the ST direction at -196/sup 0/C. The tendency of the plate to microfissuring in HAZ is very low. All these excellent properties are attributed to the improved internal soundness of the material.

Miyagi, Y.; Fujino, M.; Hino, M.; Yanai, H.

1985-03-01

118

Thickness resonances dispersion characteristics of a lossy piezoceramic plate with electrodes of arbitrary conductivity.  

PubMed

A theoretical description of the dissipative phenomena in the wave dispersion related to the "energytrap" effect in a thickness-vibrating, infinite thicknesspolarized piezoceramic plate with resistive electrodes is presented. The three-dimensional (3-D) equations of linear piezoelectricity were used to obtain symmetric and antisymmetric solutions of plane harmonic waves and investigate the eigen-modes of thickness longitudinal (TL) up to third harmonic and shear (TSh) up to ninth harmonic vibrations of odd- and even-orders. The effects of internal and electrode energy dissipation parameters on the wave propagation under regimes ranging from a short-circuit (sc) condition through RC-type relaxation dispersion to an opencircuit (oc) condition are examined in detail for PZT piezoceramics with three characteristic T -mode energy-trap figure-of-merit c-(D)(33)/c-(E)(44) values - less, near equal and higher 4 - when the second harmonic spurious TSh resonance lies below, inside, and above the fundamental TL resonanceantiresonance frequency interval. Calculated complex lateral wave number dispersion dependences on frequency and electrode resistance are found to follow the universal scaling formula similar to those for dielectrics characterization. Formally represented as a Cole-Cole diagram, the dispersion branches basically exhibit Debye-like and modified Davidson Cole dependences. Varying the dissipation parameters of internal loss and electrode conductivity, the interaction of different branches was demonstrated by analytical and numerical analysis. For the purposes of dispersion characterization of at least any thickness resonance, the following theorem was stated: the ratio of two characteristic determinants, specifically constructed from the oc and sc boundary conditions, in the limit of zero lateral wave number, is equal to the basic elementary-mode normalized admittance. As was found based on the theorem, the dispersion near the basic and nonbasic TL and TSh resonances reveal some simple representations related to the respective elementary admittance and showing the connection between the propagation and excitation problems in a continuous piezoactive medium. PMID:18276573

Mezheritsky, Alex A; Mezheritsky, Alex V

2007-12-01

119

Axisymmetric bending analysis of thick functionally graded circular plates using fourth-order shear deformation theory  

Microsoft Academic Search

In the present article, axisymmetric bending and stretching of functionally graded (FG) circular plates subjected to uniform transverse loading based on fourth-order shear deformation plate theory (FOST) have been studied. Using a fourth-order shear deformation theory, the solutions for deflection and rotation functions of FG plates are presented in terms of the corresponding quantities for a homogeneous plate using the

S. Sahraee; A. R. Saidi

2009-01-01

120

Simulation results on a resistive plate chamber for a bakelite thickness of 1 mm up to 3 mm  

Microsoft Academic Search

The performance of bakelite electrodes with thicknesses of 1, 2, and 3 mm in a double-gap resistive plate chamber (RPC) have been tested by GEANT-based Monte Carlo simulation. Results show that the thickness of bakelite plays an important role in detecting particle signals. For checking the efficiency of these RPCs, gamma particles in the range 0.01-100 MeV have been simulated

J. T. Rhee; M. Jamil

2005-01-01

121

Laser-Assisted Stir Welding of 25-mm-Thick HSLA-65 Plate  

NASA Astrophysics Data System (ADS)

Laser-assisted stir welding is a hybrid process that combines energy from a laser with functional heating and mechanical energy to join materials in the solid state. The technology is an adaptation of friction stir welding which is particularly suited for joining thick plates. Aluminum plates up to 75 mm thick have been successfully joined using friction stir welding. Since joining occurs in the solid state, stir technology offers the capability for fabricating full penetration joints in thick plates with better mechanical properties and less weld distortion than is possible by fusion processes. Currently friction stir welding is being used in several industries to improve productivity, reduce weight, and increase the strength of welded structures. Examples include: (a) the aircraft/aerospace industry where stir technology is currently being used to fabricate the space shuttle's external tank as well as components of the Delta family of rockets; (b) the shipping industry where container manufacturers are using stir technology to produce lighter containers with more payload capacity; and (c) the oil industry where offshore platform manufactures are using automated stir welding plants to fabricate large panels and structures up to 16 meters long with widths as required. In all these cases, stir technology has been restricted to aluminum alloys; however, stainless and HSLA 65 steels have been recently stir welded with friction as the primary heat source. One of the difficulties in adapting stir welding to steel is tool wear aggravated by the high tool rubbing velocities needed to provide frictional heat input into the material. Early work showed that the tool shoulder reached temperatures above 1000 C and the weld seam behind the tool stayed within this temperature range for up to 25 mm behind the tool. Cross sections of stir welded samples showed that the heat-affected zone is relatively wide and follows the profile of the tool shoulder. Besides minimizing the tool wear by increasing the energy into the material, another benefit of the proposed Laser Assisted Stir Welding (LASW is to reduce the width of the heat affected zone which typically has the lowest hardness in the weld region. Additionally, thermal modeling of the friction stir process shows that the heat input is asymmetric and suggests that the degree of asymmetry could improve the efficiency of the process. These asymmetries occur because the leading edge of the tool supplies heat to cold material while the trailing edge provides heat to material already preheated by the leading edge. As a result, flow stresses on the advancing side of the joint are lower than corresponding values on the retreating side. The proposed LASW process enhances these asymmetries by providing directional heating to increase the differential in flow stress across the joint and improve the stir tool efficiency. Theoretically the LASW process can provide the energy input to allow the flow stresses on the advancing side to approach zero and the stir efficiency to approach 100 percent. Reducing the flow stresses on the advancing side of the weld creates the greatest pressure differential across the stir weld and eliminates the possibility of voids on the advancing side of the joint. Small pressure differentials result in poor stir welds because voids on the advancing side are not filled by the plastic flow of material from the retreating side.

Williamson, Keith M.

2002-12-01

122

Optical thickness measurement of mask blank glass plate by the excess fraction method using a wavelength-tuning interferometer  

NASA Astrophysics Data System (ADS)

The absolute optical thickness of a 140-mm2 mask blank glass plate 3.1 mm thickness was measured by three-surface interferometry using a wavelength-tuning Fizeau interferometer. The interference order was determined by the excess fraction method. The wavelength of a tunable laser diode was scanned linearly from 632 to 642 nm, and a CCD detector recorded 2000 interference images. Two kinds of optical thicknesses measured by discrete Fourier analysis and phase-shifting were synthesized to obtain the optical thickness with respect to the ordinary refractive index. The optical thickness defined by the group refractive index at the 637 nm central wavelength was measured by wavelength scanning. The optical thickness deviation defined by the ordinary refractive index was measured using tunable phase-shifting. The systematic errors caused by nonlinearity in the wavelength tuning were corrected through correlation analysis between the theoretical and observed interference fringes.

Kim, Yangjin; Hibino, Kenichi; Sugita, Naohiko; Mitsuishi, Mamoru

2013-10-01

123

Perforation of 12 mm thick steel plates by 20 mm diameter projectiles with flat, hemispherical and conical noses  

Microsoft Academic Search

Projectiles with three different nose shapes (blunt, hemispherical and conical) have been used in gas gun experiments to penetrate 12mm thick Weldox 460E steel plates. Based on the experimental results, the residual velocity curves of the target material were constructed and compared. It was found that the nose shape of the projectile significantly affected both the energy absorption mechanism and

T Børvik; M Langseth; O. S Hopperstad; K. A Malo

2002-01-01

124

Analysis of Thick Rectangular Plates with Symmetric Cross-ply Laminates Based on First-order Shear Deformation Theory  

Microsoft Academic Search

A new numerical technique, the discrete singular convolution (DSC) method, is developed for static analysis of thick symmetric cross-ply laminated composite plates based on the first-order shear deformation theory of Whitney and Pagano [1]. Regularized Shannon's delta (RSD) kernel and Lagrange delta sequence (LDS) kernel are selected as singular convolution to illustrate the present algorithm. In the proposed approach, the

Ömer Civalek

2008-01-01

125

Lattice Theory of Face-Shear and Thickness-Twist Waves in Body-Centered Cubic Crystal Plates.  

National Technical Information Service (NTIS)

An analytical study is made of face-shear and thickness-twist waves propagating along the (100) and (110) directions of a body-centered cubic lattice plate bounded by a pair of (001) surfaces. The behavior of the waves in the (110) direction is similar to...

C. Gong

1970-01-01

126

Influence of porous-coating thickness on the stability and transition of flat-plate supersonic boundary layer  

NASA Astrophysics Data System (ADS)

In the present study, we examined, both experimentally and theoretically, the influence of porouscoating thickness on the stability and laminar-turbulent transition of flat-plate supersonic boundary layer at free-stream Mach number M? = 2. A qualitative agreement between the data calculated by the linear theory of stability and the experimental data on the transition obtained for models with different porous-coating thicknesses was established. We show that with decreasing (within a certain interval) the porouscoating thickness the boundary layer becomes more stable to perturbations, and the laminar-turbulent transition, more delayed.

Gaponov, S. A.; Ermolaev, Yu. G.; Kosinov, A. D.; Lysenko, V. I.; Semenov, N. V.; Smorodskii, B. V.

2012-12-01

127

Thick shell tectonics on one-plate planets - Applications to Mars  

NASA Technical Reports Server (NTRS)

Using the zero frequency equations of a self-gravitating elastic spherical shell overlying a strengthless fluid, a theory for stress distribution in thick lithospheric shells on one-plate planets is developed. For both the compensated and flexural modes, stress distributions in lithospheres are reviewed. For compensated modes, surface stresses depend only on surface topography, whereas for flexural modes it is shown that, for long wavelengths, stress trajectories are mainly dependent on the lithospheric lateral density distribution and not on elastic properties. Computational analyses are performed for Mars, and it is found that isostatically compensated models correctly predict the graben structure in the immediate Tharsis region and a flexural loading model is satisfactory in explaining the graben in the regions surrounding Tharsis. A three-stage model for the evolution of Tharsis is hypothesized: isostasy with north-south graben formation on Tharsis, followed by flexural loading and radial graben formation on the perimeter of Tharsis, followed by a last stage of loading with little or no regional deformation.

Banerdt, W. B.; Saunders, R. S.; Phillips, R. J.; Sleep, N. H.

1982-01-01

128

Understanding LIP formation in relation to lithospheric thickness, plate boundaries and plumes from a global plate tectonic perspective  

NASA Astrophysics Data System (ADS)

Large igneous provinces (LIPs) have been defined as either forming in a range of tectonic settings, or predominantly in intraplate tectonic settings. Using plate tectonic reconstructions for the past 200 million years we investigate the relationships between LIP formation, the condition of the underlying lithosphere, and the type and proximity of the closest plume and plate boundaries. We assess >70 continental and oceanic LIPs and ~70 proposed hotspots in the framework of a global plate tectonic model which incorporates dynamically evolving plate boundaries. We investigate (1) the age of the lithosphere LIPs form on (ii) the most likely plume responsible for the formation of each LIP, (iii) differences between the surface expressions of 'deep' versus 'shallow' plumes, and (iv) relationships between active plate boundaries and triple junctions, and LIP formation. A key result of our analysis is that oceanic LIPs, other than seamount chains, form on young oceanic lithosphere (mean age of ~17 million years). We also find that the majority of these oceanic LIPs form within close proximity to hotspots that have previously been classified as originating from deep within the mantle on the basis of criteria such as seismic tomography, isotopic signature, buoyancy and associated seamount chains.

Whittaker, J. M.; Landgrebe, T. C.; Seton, M.; Williams, S.; Matthews, K. J.; Müller, R.

2012-12-01

129

Postbuckling Response of Long Thick Plates Loaded in Compression Including Higher Order Transverse Shearing Effects.  

National Technical Information Service (NTIS)

Buckling and postbuckling results are presented for compression-loaded simply-supported aluminum plates and composite plates with a symmetric lay-up of thin + or - 45 deg plies composed of many layers. Buckling results for aluminum plates of finite length...

M. Stein P. D. Sydow L. Librescu

1990-01-01

130

Numerical modeling and measurement by pulsed television holography of ultrasonic displacement maps in plates with through-thickness defects  

NASA Astrophysics Data System (ADS)

We present a novel numerical modeling of ultrasonic Lamb and Rayleigh wave propagation and scattering by through-thickness defects like holes and slots in homogeneous plates, and its experimental verification in both near and far field by a self-developed pulsed TV holography system. In contrast to rigorous vectorial formulation of elasticity theory, our model is based on the 2-D scalar wave equation over the plate surface, with specific boundary conditions in the defects and plate edges. The experimental data include complex amplitude maps of the out-of-plane displacements of the plate surface, obtained by a two-step spatiotemporal Fourier transform method. We find a fair match between the numerical and experimental results, which allows for quantitative characterization of the defects.

López-Vázquez, J. Carlos; Deán-Ben, X. Luís; Trillo, Cristina; Doval, Ángel F.; Fernández, José L.; Amlani, Faisal; Bruno, Oscar P.

2010-09-01

131

Standardization and application of indirect plate ELISA for immunodiagnosis of paramphistomosis in ruminants  

Microsoft Academic Search

Indirect plate enzyme-linked immunosorbent assay was standardized and evaluated for its effectiveness in immunodiagnosis of\\u000a paramphistomosis in experimental and clinical cases in sheep, goat, cattle and buffaloes by using somatic whole adult antigen\\u000a of Paramphistomum epiclitum and Gastrothylax crumenifer. Plate enzymelinked immunosorbent assay (ELISA) was standardized using 2 ?g\\/ml of antigen concentration with 1:200 and 1:1,000\\u000a of sera and conjugate

Shivjot Kaur; L. D. Singla; S. S. Hassan; P. D. Juyal

2009-01-01

132

Effect of Backing Plate Thermal Property on Friction Stir Welding of 25-mm-Thick AA6061  

NASA Astrophysics Data System (ADS)

By using backing plates made out of materials with widely varying thermal diffusivity this work seeks to elucidate the effects of the root side thermal boundary condition on weld process variables and resulting joint properties. Welds were made in 25.4-mm-thick AA6061 using ceramic, titanium, steel, and aluminum as backing plate (BP) material. Welds were also made using a "composite backing plate" consisting of longitudinal narrow strip of low diffusivity material at the center and two side plates of high diffusivity aluminum. Stir zone temperature during the welding was measured using two thermocouples spot welded at the core of the probe: one at the midplane height and another near the tip of the probe corresponding to the root of the weld. Steady state midplane probe temperatures for all the BPs used were found to be very similar. Near root peak temperature, however, varied significantly among weld made with different BPs all other things being equal. Whereas the near root and midplane temperature were the same in the case of ceramic backing plate, the root peak temperature was 318 K (45 °C) less than the midplane temperature in the case of aluminum BP. The trends of nugget hardness and grain size in through thickness direction were in agreement with the measured probe temperatures. Hardness and tensile test results show that the use of composite BP results in stronger joint compared to monolithic steel BP.

Upadhyay, Piyush; Reynolds, Anthony

2014-04-01

133

Observation of spatter formation mechanisms in high-power fiber laser welding of thick plate  

NASA Astrophysics Data System (ADS)

This paper aims to present the dynamic behaviors of spatter formation, and to clarify the spatter formation mechanisms in the high-power fiber laser welding of a thick plate at low welding speeds. We used a modified "sandwich" specimen to directly observe the geometry of the longitudinal keyhole wall. The dynamic behaviors of the keyhole, vapor plume, and melt pool with the formation of spatters were observed using high-speed imaging. The mechanisms of the formation of the spatter ejected from the top and bottom surfaces were analyzed. The recoil momentum associated with the energized vapor plume jet acts on the tips of the gauffers on the front keyhole wall and micro-droplets inside the keyhole, thereby resulting in the formation of high-speed micro-spatter. At partial penetration, the spatter ejected from the keyhole inlet is influenced mainly by the upward melt flow above the keyhole, melt displacement around the keyhole, and the strong shear stream of the directed vapor plume force. Moreover, some spatter droplets are accelerated through the vapor plume outside the keyhole. At full penetration of the melt, spatters are generated when the downward momentum of the melt due to downward flow and gravity, or vapor burst with an open keyhole, exceeds the surface tension forces. At full penetration of the keyhole, the crucial driving force for spatter generation is the viscous friction drag associated with high-speed motion of the energized vapor plume through the open keyhole. The welding process evolves into almost a cutting process at a lower welding speed.

Zhang, M. J.; Chen, G. Y.; Zhou, Y.; Li, S. C.; Deng, H.

2013-09-01

134

A finite volume method for analysing the bending deformation of thick and thin plates  

Microsoft Academic Search

The formulation of a novel finite volume based procedure for determining deformations and moment distributions within transversely loaded plates is described in detail. The formulation employs the Mindlin theory of plate deformation. Transverse displacement and bending moment distributions are determined for a number of test problems. The effect of mesh refinement upon the accuracy of the displacement and moment fields

M. A. Wheel

1997-01-01

135

Thickness-shear vibration of an AT-cut quartz plate with elliptical electrodes and implications in optimal blank geometry.  

PubMed

We analyze thickness-shear vibration of an AT-cut quartz plate with elliptical electrodes. The electrodes are essentially optimal in the sense of Mindlin in that they approximately satisfy the criterion for Bechmann's number in every direction. The results of our analysis suggest that optimal crystal blank geometry is essentially elliptical. We also suggest a way of machining elliptical crystal blanks. PMID:19406718

Xu, Limei; Geng, Yunlong; Hu, Yuantai; Fan, Hui; Yang, Jiashi

2009-04-01

136

Three dimensional static and dynamic analysis of thick functionally graded plates by the meshless local Petrov–Galerkin (MLPG) method  

Microsoft Academic Search

In this paper, three dimensional (3D) static and dynamic analysis of thick functionally graded plates based on the Meshless Local Petrov–Galerkin (MLPG) is presented. Using the kinematics of a three-dimensional continuum, the local weak form of the equilibrium equations is derived. A weak formulation for the set of governing equations is transformed into local integral equations on local sub-domains using

A. Rezaei Mojdehi; A. Darvizeh; A. Basti; H. Rajabi

2011-01-01

137

Differential Quadrature and RAYLEIGH RITZ Methods to Determine the Fundamental Frequencies of Simply Supported Rectangular Plates with Linearly Varying Thickness  

NASA Astrophysics Data System (ADS)

In this paper, differential quadrature and Rayleigh-Ritz methods are presented for computation of the fundamental frequency of simply supported, homogeneous, isotropic, thin rectangular plates with the thickness tapering linearly in one direction. The complete analytical formulation and solution procedure is presented for both methods. Results obtained by these two methods are compared with available results in the literature and by the finite element method. Effects of the level of discretization, aspect and taper ratios are also presented.

Kukreti, A. R.; Farsa, J.; Bert, C. W.

1996-01-01

138

Deposition of thick TiAlN coatings on 2024 Al\\/SiC p substrate by Arc ion plating  

Microsoft Academic Search

Aluminum-matrix composites with particulate SiC ceramic reinforcements (Al\\/SiCp) have received much attention for space and aircraft propulsion applications. It is imperative to deposit thick hard coatings on these composites for protection. TiAlN coatings with a Ti interlayer were deposited by arc ion plating (AIP) on 2024 Al\\/SiCp substrates at various nitrogen flow rates. It was found that when the nitrogen

Sheng-Sheng Zhao; Hao Du; Jing-Di Zheng; Ying Yang; Wei Wang; Jun Gong; Chao Sun

2008-01-01

139

Effect of interlayer thickness on shear deformation behavior of AA5083 aluminum alloy\\/SS41 steel plates manufactured by explosive welding  

Microsoft Academic Search

An AA5083 aluminum alloy plate and an SS41 steel plate were cladded by an explosive welding method using an AA1050 aluminum alloy interlayer plate. The effects of the interlayer thickness on the interface morphology and the shear deformation behavior of the cladded plates were studied. The interfacial zone was composed of an intermetallic compound, FeAl3, formed by the AA1050 interlayer.

Jun Hyun Han; Jae Pyoung Ahn; Myung Chul Shin

2003-01-01

140

Scattering of the fundamental shear horizontal guided wave by a part-thickness crack in an isotropic plate.  

PubMed

The interaction of the fundamental shear horizontal (SH0) guided mode with part-thickness cracks in an isotropic plate is studied as an extension within the context and general framework of previous work ["Short range scattering of the fundamental shear horizontal guided wave mode normally incident at a through thickness crack in an isotropic plate," J. Acoust Soc. Am. 122, 1527-1538 (2007); "Angular influence on scattering when the fundamental shear horizontal guided wave mode is incident at a through-thickness crack in an isotropic plate," J. Acoust. Soc. Am. 124, 2021-2030 (2008)] by the authors with through-cracks. The symmetric incidence case where the principal direction of the incident beam bisects the crack face at 90 degrees is studied using finite element simulations validated by experiments and analysis, and conclusions are inferred for general incidence angles using insights obtained with the through-thickness studies. The influence of the crack length and the monitoring distance on the specular reflection is first examined, followed by a study of the angular profile of the reflected field. With each crack length considered, the crack depth and operating frequencies are varied. For all crack depths studied, the trend of the results is identical to that for the corresponding through-thickness case and the values differ only by a frequency dependent scale factor. Theoretical analysis is used to understand the physical basis for such behavior and estimates are suggested for the scale factor--exact for the high-frequency scattering regime and empirical for the medium- and low-frequency regimes. PMID:19045777

Rajagopal, P; Lowe, M J S

2008-11-01

141

Development of a standard reference material for diesel mutagenicity in the Salmonella plate incorporation assay  

Microsoft Academic Search

The present study documents the mutagenicity of a new National Institute of Standards and Technology (NIST) standard reference material (SRM) in the Salmonella plate incorporation assay. This study is in response to a previous recommendation by the World Health Organization to develop large batches of new SRMs for biological and chemical research. SRM 1975 is a dichloromethane (DCM) extract of

Thomas J. Hughes; Joellen Lewtas; Larry D. Claxton

1997-01-01

142

Evaluation of Thickness Reduction in a Thin Plate Using a Non-Contact Guided Wave Technique  

NASA Astrophysics Data System (ADS)

Ultrasonic guided waves are widely being studied and successfully applied to various non-destructive tests with the advantage of a long range inspection. Recently, non-contact methods are also adopted and combined with the guided wave techniques. In this paper, an advanced technique for the nondestructive detection of thinning defects simulating hidden corrosion in thin plates using non-contact guided waves is presented. The proposed approach uses EMAT(Electro-Magnetic Acoustic Transducer) for the non-contact generation and detection of guided plate waves in aluminum plates. Interesting features of the dispersive behavior in selected wave modes are used for the detection of plate thinning. The experimental results show that the mode cutoff measurements provide a qualitative measurement of thinning defects and change in the mode group velocity can be used as quantitative parameter of thinning depth measurement.

Song, Won-Joon; Park, Ik-Keun; Kim, Tae-Hyung; Kim, Hyun-Mook; Kim, Yong-Kwon; Cho, Yong-Sang

2006-03-01

143

Effect of plastic cover thickness on top loss coefficient of flat-plate collectors  

Microsoft Academic Search

The effect of plastic cover thickness on the top heat loss coefficient of collectors with outer glass and inner Teflon glazings is investigated. The total radiative properties of the Teflon films are computed from measured normal incidence spectral data. These properties are used in the overall heat transfer analysis of the system. Results are obtained for plastic thicknesses from 12.5

N. E. Wijeysundera; M. Iqbal

1991-01-01

144

Design and construction of a full-thickness guarded hot plate test system  

Microsoft Academic Search

The need to determine the thermal performance of thick, light-density fibrous insulating materials at full manufactured thickness has necessitated the design and construction of new, large test equipment. The technical challenges imposed by thicker, high R-value insulation test samples and longer system time constants have increased the stability and precision measurement requirements of all system parameters. This paper describes the

Messmer

1983-01-01

145

Propagation of the transverse normal stress in a thick plate due to distributed lateral impulsive loadings  

NASA Technical Reports Server (NTRS)

A theoretical study of the elastic stresses produced in an infinite plate when struck by a high-speed object is presented. The solution is obtained by means of linear elasticity. Laplace transformation techniques are employed to solve the axisymmetric problem. The plate is loaded normal to its surface with a uniform load over a circular area. The normal stress at the wave front of the unreflected dilatation wave along the axis and its variation with the radius of loading are determined. Various facets of the problem are discussed.

Oline, L. W.

1972-01-01

146

Application of MMC model on simulation of shearing process of thick hot-rolled high strength steel plate  

NASA Astrophysics Data System (ADS)

Shear operation is widely used as the first step in sheet metal forming to cut the sheet or plate into the required size. The shear of thick hot-rolled High Strength Steel (HSS) requires large shearing force and the sheared edge quality is relatively poor because of the large thickness and high strength compared with the traditional low carbon steel. Bad sheared edge quality will easily lead to edge cracking during the post-forming process. This study investigates the shearing process of thick hot-rolled HSS plate metal, which is generally exploited as the beam of heavy trucks. The Modified Mohr-Coulomb fracture criterion (MMC) is employed in numerical simulation to calculate the initiation and propagation of cracks during the process evolution. Tensile specimens are designed to obtain various stress states in tension. Equivalent fracture strains are measured with Digital Image Correlation (DIC) equipment to constitute the fracture locus. Simulation of the tension test is carried out to check the fracture model. Then the MMC model is applied to the simulation of the shearing process, and the simulation results show that the MMC model predicts the ductile fracture successfully.

Dong, Liang; Li, Shuhui; Yang, Bing; Gao, Yongsheng

2013-12-01

147

Exact Solution for Thermoelastic Deformations of Functionally Graded Thick Rectangular Plates  

Microsoft Academic Search

An exact solution is obtained for three-dimensional deformations of a simply supported functionally graded rectangular plate subjected to mechanical and thermal loads on its top and\\/or bottom surfaces. Suitable temper- ature and displacement functions that identically satisfy boundary conditions at the edges are used to reduce the partial differential equations governing the thermomechanical deformations to a set of coupled ordinary

Senthil S. Vel; R. C. Batra

2002-01-01

148

The finite element analysis on frequency shift of a piezoelectric plate operating in the thickness-shear mode under biasing fields  

Microsoft Academic Search

Based on the theory for small fields superposed on finite biasing fields, the finite element model of a high frequency, double-layer plate, thickness-shear vibration pressure sensor under biasing field is set up, and a biasing field finite element method (BFFEM) is proposed. Both ends of the piezoelectric plate, vibrating in thickness-shear mode, are subjected to bending moment and axial force,

Xing-ye Shan; Hong-ping Hu; Huan Xue; Yuan-tai Hu

2010-01-01

149

Postbuckling of long thick plates in compression including higher order transverse shearing effects  

NASA Technical Reports Server (NTRS)

Aluminum plates of various length/width ratios loaded in compression are examined analytically in terms of buckling and postbuckling for comparison with classical theory. The plates are considered to be subjected to longitudinal compressive displacement with no edge stress and are assumed to be simply supported at the side edges. The average longitudinal direct stresses are computed to plot characteristic curves by means of the following theories: 3D flexibility, higher-order shear deformation, first-order shear deformation, and classical von Karman. The 3D flexibility approach yields the lowest results with more unknowns than the higher-order shear-deformation method. The 3D flexibility approach is considered to be the most accurate, and it is shown that the calculated resultants and displacements tend to vary when consideration is given to the effects of transverse shear.

Stein, Manuel; Sydow, P. D.; Librescu, Liviu

1990-01-01

150

Levy-Type Solution for Bending-Stretching of Thick Functionally Graded Rectangular Plates Based on Third-order Shear Deformation Theory  

Microsoft Academic Search

In this article, an analytical approach for bending-stretching analysis of thick functionally graded rectangular plates is presented. The governing equilibrium equations are obtained based on the third-order shear deformation plate theory. Introducing four new analytical functions and doing some algebraic operations, five highly coupled governing equilibrium equations are converted into two independent partial differential equations in terms of transverse displacement

A. R. Saidi; M. Bodaghi; S. R. Atashipour

2012-01-01

151

Simplified model for oblique penetration of long-rod into plates of finite thickness  

NASA Astrophysics Data System (ADS)

A simplified calculation model describes the penetration phenomena of ricochet, embedment and perforation for long-rod penetrators impacting into homogeneous plates at various angles, and gives the profiles of craters and the bulge on the back of targets. The striking velocity range is from 900m/s to 1800m/s. The calculations for the model conform relatively well to test results.

Zhao, Guozhi

152

78 FR 65554 - Exhaust Emission Standards for New Aircraft Turbine Engines and Identification Plate for Aircraft...  

Federal Register 2010, 2011, 2012, 2013

...45 [Docket No.: FAA-2012-1333; Amendment No. 34-5A] RIN 2120-AK15 Exhaust Emission Standards for New Aircraft Turbine Engines and Identification Plate for Aircraft Engines Correction In rule document 2013-24712, appearing on pages...

2013-11-01

153

An analysis of nonlinear vibrations of coupled thickness-shear and flexural modes of quartz crystal plates with the homotopy analysis method.  

PubMed

We investigated the nonlinear vibrations of the coupled thickness-shear and flexural modes of quartz crystal plates with the nonlinear Mindlin plate equations, taking into consideration the kinematic and material nonlinearities. The nonlinear Mindlin plate equations for strongly coupled thickness- shear and flexural modes have been established by following Mindlin with the nonlinear constitutive relations and approximation procedures. Based on the long thickness-shear wave approximation and aided by corresponding linear solutions, the nonlinear equation of thickness-shear vibrations of quartz crystal plate has been solved by the combination of the Galerkin and homotopy analysis methods. The amplitude frequency relation we obtained showed that the nonlinear frequency of thickness-shear vibrations depends on the vibration amplitude, thickness, and length of plate, which is significantly different from the linear case. Numerical results from this study also indicated that neither kinematic nor material nonlinearities are the main factors in frequency shifts and performance fluctuation of the quartz crystal resonators we have observed. These efforts will result in applicable solution techniques for further studies of nonlinear effects of quartz plates under bias fields for the precise analysis and design of quartz crystal resonators. PMID:22293733

Wu, Rongxing; Wang, Ji; Du, Jianke; Huang, Dejin; Yan, Wei; Hu, Yuantai

2012-01-01

154

Longitudinal change in femorotibial cartilage thickness and subchondral bone plate area in male and female adolescent vs. mature athletes.  

PubMed

Little is known about changes in human cartilage thickness and subchondral bone plate area (tAB) during growth. The objective of this study was to explore longitudinal change in femorotibial cartilage thickness and tAB in adolescent athletes, and to compare these data with those of mature former athletes. Twenty young (baseline age 16.0±0.6 years) and 20 mature (46.3±4.7 years) volleyball athletes were studied (10 men and 10 women in each group). Magnetic resonance images were acquired at baseline and at year 2-follow-up, and longitudinal changes in cartilage thickness and tAB were determined quantitatively after segmentation. The yearly increase in total femorotibial cartilage thickness was 0.8% (95% confidence interval [CI]: -0.5; 2.1%) in young men and 1.4% (95% CI: 0.7; 2.2%) in young women; the gain in tAB was 0.4% (95% CI: -0.1; 0.8%) and 0.7% (95% CI: 0.2; 1.2%), respectively (no significant difference between sexes). The cartilage thickness increase was greatest in the medial femur, and was not significantly associated with the variability in tAB growth (r=-0.19). Mature athletes showed smaller gains in tAB, and lost >1% of femorotibial cartilage per annum, with the greatest loss observed in the lateral tibia. In conclusion, we find an increase in cartilage thickness (and some in tAB) in young athletes toward the end of adolescence. This increase appeared somewhat greater in women than men, but the differences between both sexes did not reach statistical significance. Mature (former) athletes displayed high rates of (lateral) femorotibial cartilage loss, potentially due to a high prevalence of knee injuries. PMID:24439995

Eckstein, Felix; Boeth, Heide; Diederichs, Gerd; Wirth, Wolfgang; Hudelmaier, Martin; Cotofana, Sebastian; Hofmann-Amtenbrink, Margarethe; Duda, Georg

2014-05-01

155

Estimation of ultrasonic guided wave mode conversion in a plate with thickness variation  

Microsoft Academic Search

The hybrid boundary element method aimed at analyzing Lamb wave scattering from defects can provide us with an excellent numerical tool for tackling complicated mode conversion phenomena under waveguide thickness variation. In this paper, utilization of hybrid boundary element modeling for specific Lamb wave mode incidence situations with special energy distributions along the structural cross section is proposed for estimating

Younho Cho

2000-01-01

156

A Tool Measuring Remaining Thickness of Notched Acoustic Cavities in Primary Reaction Control Thruster NDI Standards  

NASA Technical Reports Server (NTRS)

Stress corrosion cracking in the relief radius area of a space shuttle primary reaction control thruster is an issue of concern. The current approach for monitoring of potential crack growth is nondestructive inspection (NDI) of remaining thickness (RT) to the acoustic cavities using an eddy current or remote field eddy current probe. EDM manufacturers have difficulty in providing accurate RT calibration standards. Significant error in the RT values of NDI calibration standards could lead to a mistaken judgment of cracking condition of a thruster under inspection. A tool based on eddy current principle has been developed to measure the RT at each acoustic cavity of a calibration standard in order to validate that the standard meets the sample design criteria.

Sun, Yushi; Sun, Changhong; Zhu, Harry; Wincheski, Buzz

2006-01-01

157

Surface imperfection and wringing thickness in uncertainty estimation of end standards calibration  

NASA Astrophysics Data System (ADS)

Empirical estimation of uncertainty in dimensional metrology is a vital part in calibration processes. Uncertainty estimation in gauge block measurement mainly depends on three major areas, thermal effects, dimension metrology system that includes measurement strategy, and end standard surface perfection grades. This paper focuses precisely to estimate the uncertainty due to the geometrical imperfection of measuring surfaces and wringing thickness U(Lg+Lw) in calibration of end standards grade 0. An optomechanical system equipped with Zygo interferometer and AFM techniques have been employed. A novel protocol of measurement covering the geometric form of end standard surfaces and wrung base platen was experimentally applied. Surface imperfection characteristics of commonly used 6.5 mm GB have been achieved by AFM in 2D and 3D to be applied in three sets of experiments. The results show that there are obvious mapping relations between geometrical imperfection and wringing thickness of the end standards calibration. Moreover, the predicted uncertainties are clearly estimated within an acceptable range from 0.132 to 0.202 ?m respectively. Experimental and analytical results are also presented and discussed.

Ali, Salah H. R.; Naeim, Ihab H.

2014-09-01

158

Comparison of Residual Stress Distributions of Similar and Dissimilar Thick Butt-Weld Plates  

NASA Astrophysics Data System (ADS)

Residual stress distributions of 35 mm thick dissimilar metal butt-weld between A533B ferritic steel and Type 304 austenitic stainless steel (304SS) with Ni alloy welds and similar metal butt-weld of 304SS were measured using neutron diffraction. Effects of differences in thermal expansion coefficients (CTEs) and material strengths on the weld residual stress distributions were discussed by comparison of the residual stress distributions between the similar and dissimilar metal butt-welds. Residual stresses in the similar metal butt-weld exhibited typical distributions found in a thick butt-weld and they were distributed symmetrically on either side of the weld line. Meanwhile, asymmetric residual stress distributions were observed near the root of the dissimilar metal butt-weld, which was caused by differences in CTEs and yield strengths among both parent materials and weld metals. Transverse residual stress distribution of the dissimilar metal butt-weld was similar trend to that of the similar metal butt-weld, since effect of difference in CTEs were negligible, while magnitude of the transverse residual stress near the root depended on the yield strengths of each metal. In contrast, the normal and longitudinal residual stresses in the dissimilar metal butt-weld distributed asymmetrically on either side of weld line due to influence of differences in CTEs.

Suzuki, Hiroshi; Katsuyama, Jinya; Morii, Yukio

159

Biomechanical analysis of a new carbon fiber/flax/epoxy bone fracture plate shows less stress shielding compared to a standard clinical metal plate.  

PubMed

Femur fracture at the tip of a total hip replacement (THR), commonly known as Vancouver B1 fracture, is mainly treated using rigid metallic bone plates which may result in "stress shielding" leading to bone resorption and implant loosening. To minimize stress shielding, a new carbon fiber (CF)/Flax/Epoxy composite plate has been developed and biomechanically compared to a standard clinical metal plate. For fatigue tests, experiments were done using six artificial femurs cyclically loaded through the femoral head in axial compression for four stages: Stage 1 (intact), stage 2 (after THR insertion), stage 3 (after plate fixation of a simulated Vancouver B1 femoral midshaft fracture gap), and stage 4 (after fracture gap healing). For fracture fixation, one group was fitted with the new CF/Flax/Epoxy plate (n?=?3), whereas another group was repaired with a standard clinical metal plate (Zimmer, Warsaw, IN) (n?=?3). In addition to axial stiffness measurements, infrared thermography technique was used to capture the femur and plate surface stresses during the testing. Moreover, finite element analysis (FEA) was performed to evaluate the composite plate's axial stiffness and surface stress field. Experimental results showed that the CF/Flax/Epoxy plated femur had comparable axial stiffness (fractured?=?645?±?67?N/mm; healed?=?1731?±?109?N/mm) to the metal-plated femur (fractured?=?658?±?69?N/mm; healed?=?1751?±?39?N/mm) (p?=?1.00). However, the bone beneath the CF/Flax/Epoxy plate was the only area that had a significantly higher average surface stress (fractured?=?2.10?±?0.66?MPa; healed?=?1.89?±?0.39?MPa) compared to bone beneath the metal plate (fractured?=?1.18?±?0.93?MPa; healed?=?0.71?±?0.24?MPa) (p?plated femurs at the vicinity of nearest screw just proximal to fracture (stage 3), 21?MPa for composite and 24?MPa for metal-plated femurs at the vicinity of screw farthest away distally from fracture (stage 4). These results confirm that the new CF/Flax/Epoxy material could be a potential candidate for bone fracture plate applications as it can simultaneously provide similar mechanical stiffness and lower stress shielding (i.e., higher bone stress) compared to a standard clinical metal bone plate. PMID:24828985

Bagheri, Zahra S; Tavakkoli Avval, Pouria; Bougherara, Habiba; Aziz, Mina S R; Schemitsch, Emil H; Zdero, Radovan

2014-09-01

160

High-temperature crack-arrest behavior in 152-mm-thick SEN wide plates of quenched and tempered A 533 grade B class 1 steel  

SciTech Connect

The Heavy-Section Steel Technology (HSST) Program at the Oak Ridge National Laboratory, under the sponsorship of the US Nuclear Regulatory Commission, is conducting analytical and experimental studies aimed at understanding the circumstances that would initiate the growth of an existing crack in a reactor pressure vessel and the conditions that would lead to arrest of a propagating crack. HSST wide-plate crack-arrest tests are being performed at the National Institute of Standards and Technology (NIST), Gaithersburg, Maryland, in a 27-MN-capacity testing machine. This report contains results for two tests that used A 533 grade B class 1 material. Each test used a 1 x 1 x 0.15 m thick single-edge notched plate (a/w = 0.2) that was subjected to a linear thermal gradient along the plane of crack propagation. The thermal gradient was applied to the specimen by cooling the notched edge and heating the other edge. By varying the crack-tip temperature and transverse temperature profile, the initiation load and depth of crack propagation were changed from test to test. During each test, strain and temperature measurements were obtained as functions of position and time. Load, crack-opening displacement, and acoustic-emission data were also obtained as functions of time. 24 refs., 91 figs., 12 tabs.

Naus, D.J.; Keeney-Walker, J.; Bass, B.R.; Bolt, S.E.; Fields, R.J.; deWit, R.; Low, S.R. III

1989-04-01

161

Simulation results on a resistive plate chamber for a bakelite thickness of 1 mm up to 3 mm  

SciTech Connect

The performance of bakelite electrodes with thicknesses of 1, 2, and 3 mm in a double-gap resistive plate chamber (RPC) have been tested by GEANT-based Monte Carlo simulation. Results show that the thickness of bakelite plays an important role in detecting particle signals. For checking the efficiency of these RPCs, gamma particles in the range 0.01-100 MeV have been simulated through different bakelite setups. For an isotropic gamma source, a sensitivity s{sub {gamma}}<3.5x10{sup -2} at <100 MeV by a 1 mm bakelite double-gap RPC has been observed. For the same gamma source with a 2 mm bakelite RPC, a sensitivity s{sub {gamma}}<4.0x10{sup -2} at <100 MeV has been measured, whereas for 3 mm bakelite RPC, sensitivity results were s{sub {gamma}}<4.44x10{sup -2} at <100 MeV. Similar characteristics of bakelite electrodes have been observed for a parallel gamma source configuration.

Rhee, J.T.; Jamil, M. [Institute for Advanced Physics, Konkuk University, Seoul 143-701 (Korea, Republic of)

2005-07-15

162

Simulation results on a resistive plate chamber for a bakelite thickness of 1 mm up to 3 mm  

NASA Astrophysics Data System (ADS)

The performance of bakelite electrodes with thicknesses of 1, 2, and 3 mm in a double-gap resistive plate chamber (RPC) have been tested by GEANT-based Monte Carlo simulation. Results show that the thickness of bakelite plays an important role in detecting particle signals. For checking the efficiency of these RPCs, gamma particles in the range 0.01-100 MeV have been simulated through different bakelite setups. For an isotropic gamma source, a sensitivity s?<3.5×10-2 at <100 MeV by a 1 mm bakelite double-gap RPC has been observed. For the same gamma source with a 2 mm bakelite RPC, a sensitivity s?<4.0×10-2 at <100 MeV has been measured, whereas for 3 mm bakelite RPC, sensitivity results were s?<4.44×10-2 at <100 MeV. Similar characteristics of bakelite electrodes have been observed for a parallel gamma source configuration.

Rhee, J. T.; Jamil, M.

2005-07-01

163

Investigation of trapped thickness-twist waves induced by functionally graded piezoelectric material in an inhomogeneous plate  

NASA Astrophysics Data System (ADS)

The effect of functional graded piezoelectric materials on the propagation of thickness-twist waves is investigated through equations of the linear theory of piezoelectricity. The elastic and piezoelectric coefficients, dielectric permittivity, and mass density are assumed to change in a linear form but with different graded parameters along the wave propagation direction. We employ the power-series technique to solve the governing differential equations with variable coefficients attributed to the different graded parameters and prove the correction and convergence of this method. As a special case, the functional graded middle layer resulting from piezoelectric damage and material bonding is investigated. Piezoelectric damaged material can facilitate energy trapping, which is impossible in perfect materials. The increase in the damaged length and the reduction in the piezoelectric coefficient decrease the resonance frequency but increase the number of modes. Higher modes of thickness-twist waves appear periodically along the damaged length. Moreover, the displacement of the center of the damaged portion is neither symmetric nor anti-symmetric, unlike the non-graded plate. The conclusions are theoretically and practically significant for wave devices.

Li, Peng; Jin, Feng; Cao, Xiao-Shan

2013-09-01

164

Full-field localization of plate-thickness inhomogeneities through the local changes in the wavenumber of Lamb waves measured with pulsed TV holography  

NASA Astrophysics Data System (ADS)

A new capability of TV holography, also known as electronic speckle pattern interferometry (ESPI), is presented for locating and imaging slightly thinned or thickened areas in metallic plates. It is based on the measurement of the wavenumber variation of narrowband Lamb waves as they propagate through these plate-thickness inhomogeneities. The relation between frequency and phase velocity of all Lamb modes depends on the elastic constants of the material the plate is made of (two parameters in isotropic materials) and on the plate thickness. Therefore, the associated dispersion curve of each mode present wavenumber changes that are sensitive to a thickness reduction. We have formerly developed a double-pulsed TV holography system which allows the full-field measurement of the instantaneous out-of-plane displacement field induced by surface acoustic waves and, by further processing, to calculate maps of the acoustic amplitude and phase. A method based on further analysis of the acoustic complex-displacement map is therefore proposed to locate and characterize such smooth thickness reductions. In particular, we calculate a map of the local wavenumber of the acoustic wave as the modulus of the two-dimensional gradient of the mechanical phase. Hence, as the variations in the wavenumber correspond to variations in the plate thickness, the local thickness reductions and increments can be detected in this map. Within the resolution limits imposed by the wavelength of the Lamb wave, this method allows also to contour the shape of the inhomogeneities. The technique is demonstrated herein by imaging a X-shaped recess machined on an aluminium plate.

Deán, J. Luis; Trillo, Cristina; Doval, Ángel F.; Fernández, José L.

2008-06-01

165

Free vibrations of simply supported nonhomogeneous isotropic rectangular plates of bilinearly varying thickness and elastically restrained edges against rotation using Rayleigh-Ritz method  

NASA Astrophysics Data System (ADS)

This paper addresses the free transverse vibrations of thin simply supported nonhomogeneous isotropic rectangular plates of bilinearly varying thickness with elastically restrained edges against rotation. The Gram-Schmidt process has been used to generate two-dimensional boundary characteristic orthogonal polynomials, which have been used in the Rayleigh-Ritz method to study the problem. The lowest three frequencies have been computed for various values of nonhomogeneous parameters, thickness parameters, aspect ratio and flexibility parameters. A comparison of the results with those available in the literature has been made. Three-dimensional mode shapes for the specified plate have been presented.

Kumar, Yajuvindra

2012-03-01

166

A generalized higher-order theory for buckling of thick multi-layered composite plates with normal and transverse shear strains  

Microsoft Academic Search

The onset of buckling in square laminated multi-layered composite plates, subject to unidirectional in-plane loads, is investigated within the framework of a generalized higher-order shear deformation theory suitable to capture significant transverse shear and thickness-wise deformation effects. The displacement field is expanded in a Taylor series of the thickness coordinate with arbitrary polynomial degree; in turn, the series coefficients, expressed

Lars Fiedler; Walter Lacarbonara; Fabrizio Vestroni

2010-01-01

167

Tectonic plate coupling and elastic thickness derived from the inversion of a steady state viscoelastic model using geodetic data: Application to southern North Island, New Zealand  

Microsoft Academic Search

A steady state viscoelastic model of deformation at an oblique convergence zone is used to analyze crustal velocities deduced from Global Positioning System (GPS) observations in southern North Island, New Zealand. The model is physically more reasonable than elastic dislocation theory because the tectonic plates have finite elastic thicknesses. In an inversion that makes use of Green's functions derived from

Steven C. Cohen; Desmond J. Darby

2003-01-01

168

A new clinical unit for digital radiography based on a thick amorphous Selenium plate: Physical and psychophysical characterization  

SciTech Connect

Purpose: Here, we present a physical and psychophysical characterization of a new clinical unit (named AcSelerate) for digital radiography based on a thick a-Se layer. We also compared images acquired with and without a software filter (named CRF) developed for reducing sharpness and noise of the images and making them similar to images coming from traditional computed radiography systems. Methods: The characterization was achieved in terms of physical figures of merit [modulation transfer function (MTF), noise power spectra (NPS), detective quantum efficiency (DQE)], and psychophysical parameters (contrast-detail analysis with an automatic reading of CDRAD images). We accomplished measurements with four standard beam conditions: RAQ3, RQA5, RQA7, and RQA9. Results: The system shows an excellent MTF (about 50% at the Nyquist frequency). The DQE is about 55% at 0.5 lp/mm and above 20% at the Nyquist frequency and is almost independent from exposure. The contrast-detail curves are comparable to some of the best published data for other systems devoted to imaging in general radiography. The CRF filter influences both the MTF and NPS, but it does lead to very small changes on DQE. Also the visibility of CDRAD details is basically unaltered, when the filter is activated. Conclusions: As normally happens with detector based on direct conversion, the system presents an excellent MTF. The improved efficiency caused by the thick layer allows getting good noise characteristics and DQE results better (about 10% on average) than many of the computed radiography (CR) systems and comparable to those obtained by the best systems for digital radiography available on the market.

Rivetti, Stefano; Lanconelli, Nico; Bertolini, Marco; Acchiappati, Domenico [Alma Mater Studiorum, Physics Department, University of Bologna, 40127 Bologna, Italy and S.C. di Fisica Sanitaria ''Azienda USL di Modena'' 41100 Modena (Italy); Alma Mater Studiorum, Physics Department, University of Bologna, 40127 Bologna (Italy); Arcispedale Santa Maria Nuova, 42123 Reggio Emilia (Italy); S.C. di Fisica Sanitaria ''Azienda USL di Modena'' 41100 Modena (Italy)

2011-08-15

169

A comparison of standard cultural methods for the detection of foodborne Salmonella species including three new chromogenic plating media  

Microsoft Academic Search

In this study the draft of the horizontal method for the detection of Salmonella species from human food and animal feed (ISO 6579:2002) was compared to the European gold standard (DIN EN 12824:1998), including the three new chromogenic plating media AES Salmonella Agar Plate (ASAP), Oxoid Salmonella Chromogen Media (OSCM) and Miller–Mallinson agar (MM). First the growth and appearance of

Vanessa Schönenbrücher; Edward T. Mallinson; Michael Bülte

2008-01-01

170

Geometrically Induced Stress Singularities of a Thick FGM Plate Based on the Third-Order Shear Deformation Theory  

Microsoft Academic Search

Asymptotic solutions for a functionally graded material (FGM) plate are developed to elucidate stress singularities at a plate corner, using a third-order shear deformation theory. The characteristic equations are given explicitly for determining the order of stress singularity at the vertex of a corner with two radial edges having various boundary conditions. The non-homogeneous elasticity properties are present only in

C. S. Huang; M. J. Chang

2009-01-01

171

Static and Dynamic Analysis of Thick Functionally Graded Plates with Piezoelectric Layers Using Layerwise Finite Element Model  

Microsoft Academic Search

In this paper, static and dynamic analysis of a functionally graded material (FGM) plate with surface-bonded piezoelectric layers is studied. A general finite element formulation based on the layerwise theory is developed for modelling an FG plate with piezoelectric layers or patches. The intermediate FG layer is assumed to be made of many sublayers. Each sublayer is considered as an

M. Shakeri; R. Mirzaeifar

2009-01-01

172

Effect of volume fraction and shape of sulfide inclusions on through-thickness ductility and impact energy of high-strength 4340 plate steels  

Microsoft Academic Search

The effect of volume fraction and shape of sulfide inclusions on the tensile ductility and impact energy of high-strength\\u000a AISI 4340 plate steels in the transverse and through-thickness testing directions was investigated for four tensile-strength\\u000a levels of 930, 1210, 1410, and 1960 MPa (135, 175, 205, and 285 ksi). The volume fraction of sulfide inclusions was changed\\u000a by varying the

G. R. Speich; W. A. Spitzig

1982-01-01

173

Effect of volume fraction and shape of sulfide inclusions on through-thickness ductility and impact energy of high-strength 4340 plate steels  

Microsoft Academic Search

The effect of volume fraction and shape of sulfide inclusions on the tensile ductility and impact energy of high-strength AISI 4340 plate steels in the transverse and through-thickness testing directions was investigated for four tensile-strength levels of 930, 1210, 1410, and 1960 MPa (135, 175, 205, and 285 ksi). The volume fraction of sulfide inclusions was changed by varying the

G. R. Speich; W. A. Spitzig

1982-01-01

174

Three-dimensional linear elastic distributions of stress and strain energy density ahead of V-shaped notches in plates of arbitrary thickness  

Microsoft Academic Search

This paper presents an analytical solution, substantiated by extensive finite element calculations, for the stress field at a notch root in a plate of arbitrary thickness. The present approach builds on two recently developed analysis methods for the in-plane stresses at notch root under plane-stress or plane strain conditions, and the out-of-plane stresses at a three-dimensional notch root. The former

Filippo Berto; Paolo Lazzarin; Chun Hui Wang

2004-01-01

175

Simple Method for Plating Escherichia coli Bacteriophages Forming Very Small Plaques or No Plaques under Standard Conditions  

Microsoft Academic Search

The use of low concentrations (optimally 2.5 to 3.5 g\\/ml, depending on top agar thickness) of ampicillin in the bottom agar of the plate allows for formation of highly visible plaques of bacteriophages which otherwise form extremely small plaques or no plaques on Escherichia coli lawns. Using this method, we were able to obtain plaques of newly isolated bacteriophages, propagated

J. M. Los; Piotr Golec; G. Wegrzyn; A. Wegrzyn; M. Los

2008-01-01

176

Tectonic Plate Coupling and Elastic Thickness Using a Viscoelastic Model of Crustal Deformation in Southern North Island, New Zealand  

Microsoft Academic Search

The crustal deformation in the Wellington region of North Island, New Zealand has been studied by inverting GPS-derived crustal velocities using a steady-state viscoelastic model of oblique plate convergence. The deformation is driven by pseudo-backslip on the locked Pacific-Australia plate interface. Finite element techniques are used to calculate effective Green functions for the slip elements and slip velocities are determined

S. C. Cohen; D. J. Darby

2001-01-01

177

Method for measuring the refractive index and the thickness of transparent plates with a lateral-shear, wavelength-scanning interferometer.  

PubMed

A new method for measuring simultaneously the thickness and the refractive index of a transparent plate is proposed. The method is based on a simple, variable lateral-shear, wavelength-scanning interferometer. To achieve highly accurate measurements of both refractive index n and thickness d we use several means to determine these two quantities. We finely tune a distributed-feedback diode laser light source to introduce a phase shift into the detected signal, whereas we make the sample rotate to produce variable lateral shearing. Phase shifting permits precise determination of the optical thickness, nd, whereas refractive index n is obtained from the retrieved phase of the overall interference signal for all incidence angles. PMID:12868826

Coppola, Giuseppe; Ferraro, Pietro; Iodice, Mario; De Nicola, Sergio

2003-07-01

178

Free and Forced Vibrations of Thick Rectangular Plates using Higher-Or~er Shear and Normal Deformable Plate Theory and Meshless Petrov-Galerkin (MLPG) Method  

Microsoft Academic Search

We use a meshless local Petrov-Galerkin Liu (2001) have used the MLPG method to find natu- (MLPG) method to analyze three-dimensional infinitesi- ral frequencies and forced plane ,strain deformations.of mal elastodynamic deformations of a homogeneous rect- a cantilever beam. Batra and Chmg .(2002~ have de!m- angular plate subjected to different edge conditions. We eated the time evolution of the stress-mtenslty

L. F. Qianl; R. C. Batra; L. M. Chenl

2003-01-01

179

Energy response of an imaging plate exposed to standard beta sources.  

PubMed

Imaging plates (IPs) are a reusable media, which when exposed to ionizing radiation, store a latent image that can be read out with a red laser as photostimulated luminescence (PSL). They are widely used as a substitute for X-ray films for diagnostic studies. In diagnostic radiology this technology is known as computed radiography. In this work, the energy response of a commercial IP to beta-particle reference radiation fields used for calibrations at the National Institute of Standards and Technology was investigated. The absorbed dose in the active storage phosphor layer was calculated following the scaling procedure for depth dose for high Z materials with reference to water. It was found that the beta particles from Pm-147 and Kr-85 gave 68% and 24% higher PSL responses than that induced by Sr-90, respectively, which was caused by the different PSL detection efficiencies. In addition, normalized response curves of the IPs as a function of depth in polystyrene were measured and compared with the data measured using extrapolation chamber techniques. The difference between both sets of data resulted from the continuous energy change as the beta particle travels across the material, which leads to a different PSL response. PMID:12406632

Gonzalez, A L; Li, H; Mitch, M; Tolk, N; Duggan, D M

2002-12-01

180

Correlation between standard plate count and somatic cell count milk quality results for Wisconsin dairy producers.  

PubMed

The objective of this study was to determine if a correlation exists between standard plate count (SPC) and somatic cell count (SCC) monthly reported results for Wisconsin dairy producers. Such a correlation may indicate that Wisconsin producers effectively controlling sanitation and milk temperature (reflected in low SPC) also have implemented good herd health management practices (reflected in low SCC). The SPC and SCC results for all grade A and B dairy producers who submitted results to the Wisconsin Department of Agriculture, Trade, and Consumer Protection, in each month of 2012 were analyzed. Grade A producer SPC results were less dispersed than grade B producer SPC results. Regression analysis showed a highly significant correlation between SPC and SCC, but the R(2) value was very small (0.02-0.03), suggesting that many other factors, besides SCC, influence SPC. Average SCC (across 12mo) for grade A and B producers decreased with an increase in the number of monthly SPC results (out of 12) that were ?25,000cfu/mL. A chi-squared test of independence showed that the proportion of monthly SCC results >250,000cells/mL varied significantly depending on whether the corresponding SPC result was ?25,000 or >25,000cfu/mL. This significant difference occurred in all months of 2012 for grade A and B producers. The results suggest that a generally consistent level of skill exists across dairy production practices affecting SPC and SCC. PMID:24630657

Borneman, Darand L; Ingham, Steve

2014-05-01

181

On the thermally-induced residual stresses in thick fiber-thermoplastic matrix (PEEK) cross-ply laminated plates  

NASA Technical Reports Server (NTRS)

An analytical method for calculating thermally-induced residual stresses in laminated plates is applied to cross-ply PEEK laminates. We considered three cooling procedures: slow cooling (uniform temperature distribution); convective and radiative cooling; and rapid cooling by quenching (constant surface temperature). Some of the calculated stresses are of sufficient magnitude to effect failure properties such as matrix microcracking.

Hu, Shoufeng; Nairn, John A.

1992-01-01

182

Orbiter Cold Plate Intergranular Corrosion: Development of NDE Standards and Assessment of NDE Methods.  

National Technical Information Service (NTIS)

During pre-servicing of a space shuttle (orbiter vehicle, OV-102), helium leak detection of an avionics cold plate identified a leak located in the face sheet oriented towards the support shelf. Subsequent destructive examination of the leaking cold plate...

S. W. Smith W. P. Winfree R. S. Piascik

2002-01-01

183

Lattice Theory of Face-Shear and Thickness-Twist Waves in Face-Centered Cubic Crystal Plates.  

National Technical Information Service (NTIS)

Finite difference equations of motion of the sixth order and the associated boundary conditions for principal planes are formulated for a face-centered cubic lattice of mass particles. The equations are solved for face-shear and thickness-twist waves in a...

K. J. Brady

1969-01-01

184

A Comparative Analysis of Standard Microtiter Plate Reading Versus Imaging in Cellular Assays  

PubMed Central

Abstract We evaluated the performance of two plate readers (the Beckman Coulter [Fullerton, CA] DTX and the PerkinElmer [Wellesley, MA] EnVision™) and a plate imager (the General Electric [Fairfield, CT] IN Cell 1000 Analyzer™) in a primary fluorescent cellular screen of 10,000 Molecular Libraries Screening Center Network library compounds for up- and down-regulation of vascular cell adhesion molecule (VCAM)-1, which has been shown to be up-regulated in artherothrombotic vascular disease and is a general indicator of chronic inflammatory disease. Prior to screening, imaging of a twofold, six-step titration of fluorescent cells in a 384-well test plate showed greater consistency, sensitivity, and dynamic range of signal detection curves throughout the detection range, as compared to the plate readers. With the same 384-well test plate, the detection limits for fluorescent protein-labeled cells on the DTX and EnVision instruments were 2,250 and 560 fluorescent cells per well, respectively, as compared to 280 on the IN Cell 1000. During VCAM screening, sensitivity was critical for detection of antagonists, which reduced brightness of the primary immunofluorescence readout; inhibitor controls yielded Z? values of 0.41 and 0.16 for the IN Cell 1000 and EnVision instruments, respectively. The best 1% of small molecule inhibitors from all platforms were visually confirmed using images from the IN Cell 1000. The EnVision and DTX plate readers mutually identified approximately 57% and 21%, respectively, of the VCAM-1 inhibitors visually confirmed in the IN Cell best 1% of inhibitors. Furthermore, the plate reader hits were largely exclusive, with only 6% agreement across all platforms (three hits out of 47). Taken together, the imager outperformed the plate readers at hit detection in this bimodal assay because of superior sensitivity and had the advantage of speeding hit confirmation during post-acquisition analysis.

Bushway, Paul J.

2008-01-01

185

Practical Bench Comparison of BBL CHROMagar Orientation and Standard Two-Plate Media for Urine Cultures  

Microsoft Academic Search

A total of 1,023 urine samples sent for routine culture were plated onto sheep blood and MacConkey agars and a BBL CHROMagar Orientation (CO; Becton Dickinson, Cockeysville, Md.) plate, and the results were compared. Of these, 250 urine samples (24%) grew >10,000 CFU of one or two putative pathogens\\/ml and 773 showed no growth (NG), mixed growth of <10,000 CFU\\/ml,

Holly A. D'Souza; Mary Campbell; Ellen Jo Baron

2004-01-01

186

Enumeration of waterborne Escherichia coli with petrifilm plates: comparison to standard methods.  

PubMed

Escherichia coli is often monitored in environmental waters as an indicator of the possible presence of human pathogens associated with feces. Petrifilm E. coli/coliform count plates (3M, Minneapolis, MN), previously validated for enumerating E. coli in food, were tested for monitoring E. coli in environmental water. Escherichia coli counts in environmental water samples enumerated with Petrifilm were significantly correlated (R > 0.9; slope = 0.9-1.0; p < 0.001) with counts obtained with three commonly used methods, mTEC (Becton Dickinson, Sparks, MD), m-ColiBlue (Hach, Loveland, CO), and Colilert-18/IDEXX Quanti-Tray 2000 (IDEXX, Westbrook, ME). Blue colonies on Petrifilm plates were most reliably identified as E. coli when accompanied by gas formation, as determined by characterization of the colonies on MacConkey agar plates (PML Microbiologicals, Mississauga, ON, Canada) and by polymerase chair reaction (PCR) with E. coli-specific primers. The main disadvantage of Petrifilm plates for environmental water testing is the small volume (1 mL per sample) that can be tested; however, the plates appear to be suitable for screening and locating sites that exceed criteria for total body and partial body contact. Simplicity of use and storage, reliability, and relatively low cost make Petrifilm plates suitable for volunteer-based and educational water quality monitoring applications, particularly when used as a preliminary screening method to identify problem sites. PMID:12549577

Vail, J H; Morgan, R; Merino, C R; Gonzales, F; Miller, R; Ram, J L

2003-01-01

187

A0 mode interaction with a plate free edge: theory and experiments at very low frequency by thickness product.  

PubMed

When a plane acoustic wave reaches a medium with an impedance infinite or null, it experiences a phase shift of zero or pi and its amplitude on the edge is maximum or vanishes. The case of a flexion wave (A0 Lamb wave) at a free end is also simple; its amplitude is multiplied by a factor 2 square root 2 and the phase shift is pi/2. The evanescent wave at the origin of these phenomena, perfectly described by the classical flexural plate theory, is identified as the imaginary A1 mode of the exact Rayleigh-Lamb theory. The experiences confirm the theoretical predictions. PMID:17672620

Ribay, Guillemette; Catheline, Stefan; Clorennec, Dominique; Ing, Ros Kiri; Fink, Mathias

2007-08-01

188

76 FR 35744 - Amendments to National Emission Standards for Hazardous Air Pollutants for Area Sources: Plating...  

Federal Register 2010, 2011, 2012, 2013

...wetting agents/fume suppressants to...such as laboratory testing, which provide equal...the fact that HAP emissions are based on the...add wetting agent/fume suppressant to replenish...plating as well as for emission control. However...more wetting agent/fume suppressant...

2011-06-20

189

76 FR 57913 - Amendments to National Emission Standards for Hazardous Air Pollutants for Area Sources: Plating...  

Federal Register 2010, 2011, 2012, 2013

...more wetting agent/fume suppressant than needed...necessarily reduce HAP emissions. This revision ensures...of the wetting agent/fume suppressant does not...plating as well as for emission control. However, adding more wetting agent/fume suppressant beyond...

2011-09-19

190

Comparison of central corneal thickness measurements with three new optical devices and a standard ultrasonic pachymeter.  

PubMed Central

AIM To compare the RTVue spectral optical coherence tomography (SD-OCT), Sirius Scheimpflug-Placido topographer, Lenstar optical low coherence reflectometry (OLCR) and ultrasound pachymetry (USP) devices in terms of their agreement and repeatability of measuring central corneal thickness (CCT). METHODS In this prospective study, 50 eyes of 50 patients were included. Three repeated measures were obtained using SD-OCT, Scheimpflug-Placido topographer and USP and five measurements were determined with the OLCR. Bland-Altman plots were used to assess agreement among the instruments, and 95% limits of agreement (LoA) for each comparison were calculated. Intra-examiner repeatability was assessed using intraclass correlation coefficients (ICCs). RESULTS The mean CCT by SD-OCT, Scheimpflug-Placido topographer, OLCR, and USP were 525.90±34.08 µm, 525.92±34.10 µm, 530.30±35.62 µm, and 543.50±37.11 µm respectively. All 4 modalities of CCT measurements correlated closely with each other, with Pearson correlation coefficients ranging from 0.977 to 0.995. The mean differences (and upper/lower LoA) for CCT measurements were -0.05±6.77 µm (13.3/-13.3) between SD-OCT and Scheimpflug-Placido topographer, 4.38±3.79 µm (11.8/-3.1) between OLCR and SD-OCT, 4.38±6.03 µm (16.2/-7.5) between OLCR and Scheimpflug-Placido topographer, 13.20±6.46 µm (25.9/0.5) between USP and OLCR, 17.59±6.76 µm (30.8/4.3) between USP and SD-OCT, and 17.58±8.13 µm (33.5/1.6) between USP and Scheimpflug-Placido topographer. Intra-examiner repeatability was excellent for all devices with ICCs>0.98. CONCLUSION For most practical purposes, CCT measurements with the RTVue, Sirius and Lenstar can be used interchangeably. Although highly correlated, CCT measurement differences between USP and these 3 optical instruments can be significant depending on the clinical situation.

Bayhan, Hasan Ali; Aslan Bayhan, Seray; Can, Izzet

2014-01-01

191

A 3D shell-like approach using element-free Galerkin method for analysis of thin and thick plate structures  

NASA Astrophysics Data System (ADS)

A new efficient meshless method based on the element-free Galerkin method is proposed to analyze the static deformation of thin and thick plate structures in this paper. Using the new 3D shell-like kinematics in analogy to the solid-shell concept of the finite element method, discretization is carried out by the nodes located on the upper and lower surfaces of the structures. The approximation of all unknown field variables is carried out by using the moving least squares (MLS) approximation scheme in the in-plane directions, while the linear interpolation is applied through the thickness direction. Thus, different boundary conditions are defined only using displacements and penalty method is used to enforce the essential boundary conditions. The constrained Galerkin weak form, which incorporates only displacement degrees of freedom (d.o.f.s), is derived. A modified 3D constitutive relationship is adopted in order to avoid or eliminate some self-locking effects. The numeric efficiency of the proposed meshless formulation is illustrated by the numeric examples.

Yin, Yu; Yao, Lin-Quan; Cao, Yang

2013-02-01

192

Real time monitoring of electroless nickel plating  

NASA Astrophysics Data System (ADS)

This work deals with the design and manufacturing of the heat and chemical resistant transducer case required for on-line immersion testing, experimental design, data acquisition and signal processing. Results are presented for several depositions with an accuracy of two ten-thousandths of an inch in coating thickness obtained. Monitoring the deposition rate of Electroless Nickel (EN) plating in-situ will provide measurement of the accurate dimensions of the component being plated, in real time. EN is used as for corrosion and wear protection for automotive an - Electroless Nickel (EN) plating is commonly used for corrosion and wear protection for automotive and aerospace components. It plates evenly and symmetrically, theoretically allowing the part to be plated to its final dimension. Currently the standard approach to monitoring the thickness of the deposited nickel is to remove the component from the plating bath and physically measure the part. This can lead to plating problems such as pitting, non-adhesion of the deposit and contamination of the plating solution. The goal of this research effort is to demonstrate that plating thickness can be rapidly and accurately measured using ultrasonic testing. Here a special housing is designed to allow immersion of the ultrasonic transducers directly into the plating bath. An FFT based signal processing algorithm was developed to resolve closely spaced echoes for precise thickness determination. The technique in this research effort was found to be capable of measuring plating thicknesses to within 0.0002 inches. It is expected that this approach will lead to cost savings in many EN plating operations.

Rains, Aaron E.; Kline, Ronald A.

2013-01-01

193

Biomechanical comparison of a unique locking plate versus a standard plate for internal fixation of proximal humerus fractures in a cadaveric model  

Microsoft Academic Search

BackgroundNewer internal fixation devices with a locking mechanism between the plate and the screw have recently been released. The efficacy of these plates in the proximal humerus has yet to be fully described. There is a need to compare the biomechanical properties of efficacy of plate fixation with or without locking screws for surgery of two-part proximal humerus fractures. Multiple-plane

Stephen Walsh; Rudy Reindl; Edward Harvey; Gregory Berry; Lorne Beckman; Thomas Steffen

2006-01-01

194

Laser induced copper plating  

Microsoft Academic Search

Argon laser induced plating of copper spots and lines from copper sulfate solutions on glass and phenolic resin paper has been investigated. The substrates had to be precoated with an evaporated copper film. The highest plating rates have been obtained with a small film thickness of 25 nm. Spots with a thickness up to 30 ?m were plated.

A. K. Al-Sufi; H. J. Eichler; J. Salk; H. J. Riedel

1983-01-01

195

Tungsten Inert Gas and Friction Stir Welding Characteristics of 4-mm-Thick 2219-T87 Plates at Room Temperature and -196 °C  

NASA Astrophysics Data System (ADS)

2219-T87 aluminum alloy is widely used for fabricating liquid rocket propellant storage tank, due to its admirable cryogenic property. Welding is the dominant joining method in the manufacturing process of aerospace components. In this study, the tungsten inert gas welding and friction stir welding (FSW) characteristics of 4-mm-thick 2219-T87 alloy plate at room temperature (25 °C) and deep cryogenic temperature (-196 °C) were investigated by property measurements and microscopy methods. The studied 2219 base alloy exhibits a low strength plane anisotropy and excellent room temperature and cryogenic mechanical properties. The ultimate tensile strength values of TIG and FSW welding joints can reach 265 and 353 MPa at room temperature, and 342 and 438 MPa at -196 °C, respectively. The base metal consists of elongated deformed grains and many nano-scaled ? (Al2Cu) aging precipitates. Fusion zone and heat-affected zone (HAZ) of the TIG joint are characterized by coarsening dendritic grains and equiaxed recrystallized grains, respectively. The FSW-welded joint consists of the weld nugget zone, thermo-mechanically affected zone (TMAZ), and HAZ. In the weld nugget zone, a micro-scaled sub-grain structure is the main microstructure characteristic. The TMAZ and HAZ are both characterized by coarsened aging precipitates and elongated deformed grains. The excellent FSW welding properties are attributed to the preservation of the working structures and homogenous chemical compositions.

Lei, Xuefeng; Deng, Ying; Yin, Zhimin; Xu, Guofu

2014-04-01

196

Angular influence on the scattering of fundamental shear horizontal guided waves by a through-thickness crack in an isotropic plate.  

PubMed

The angular influence on the scattering of cylindrical-crested waves of the fundamental shear horizontal (SH0) guided mode by through-thickness cracks in an isotropic plate is studied in the context of array imaging using ultrasonic guided waves. Finite element simulations are used to obtain trends which are subject to analytical study and experimental confirmation. The influence of the incidence angle on reflection behavior is first studied in terms of two complementary cases, that of normal incidence and that of specular reflection at various oblique incidence angles. The normal incidence study suggests that for a given incidence angle, the peak reflection is concentrated around the specular direction, while the oblique incidence studies show that maximum specular reflection occurs in the case of normal incidence. The variation of diffraction with both the angle of incidence and that of monitoring is then taken up and this shows that when the first diffraction from the crack edges can be separated, its angular dependence can be obtained from literature on similar bulk elastic wave scattering problems. PMID:19062842

Rajagopal, P; Lowe, M J S

2008-10-01

197

Short range scattering of the fundamental shear horizontal guided wave mode normally incident at a through-thickness crack in an isotropic plate.  

PubMed

Interaction of the fundamental shear horizontal mode with through-thickness cracks in an isotropic plate is studied in the context of low frequency array imaging for ultrasonic guided wave nondestructive evaluation with improved resolution. Circular wave fronts are used and the symmetric case where a line from the wave source bisects the crack face normally is considered. Finite element simulations are employed to obtain trends subject to analytical and experimental validation. The influence of the crack length and of the location of source and measurement positions on the specular reflection from the crack face is first examined. These studies show that low frequency short range scattering is strongly affected by diffraction phenomena, leading to focusing of energy by the crack in the backscatter direction. Study of the diffraction from the crack edges reveals contributions due to a direct diffraction at the edges and multiple reverberations across the crack length. A simple diffraction model is shown to adequately represent cracks up to moderate lengths, providing an easy means of estimating the far field of the waves. The presence of multiple diffraction components is quantitatively established and surface waves on the crack face are identified as equivalent to low frequency symmetric modes of rectangular ridge waveguides. PMID:17927412

Rajagopal, P; Lowe, M J S

2007-09-01

198

Tungsten Inert Gas and Friction Stir Welding Characteristics of 4-mm-Thick 2219-T87 Plates at Room Temperature and -196 °C  

NASA Astrophysics Data System (ADS)

2219-T87 aluminum alloy is widely used for fabricating liquid rocket propellant storage tank, due to its admirable cryogenic property. Welding is the dominant joining method in the manufacturing process of aerospace components. In this study, the tungsten inert gas welding and friction stir welding (FSW) characteristics of 4-mm-thick 2219-T87 alloy plate at room temperature (25 °C) and deep cryogenic temperature (-196 °C) were investigated by property measurements and microscopy methods. The studied 2219 base alloy exhibits a low strength plane anisotropy and excellent room temperature and cryogenic mechanical properties. The ultimate tensile strength values of TIG and FSW welding joints can reach 265 and 353 MPa at room temperature, and 342 and 438 MPa at -196 °C, respectively. The base metal consists of elongated deformed grains and many nano-scaled ? (Al2Cu) aging precipitates. Fusion zone and heat-affected zone (HAZ) of the TIG joint are characterized by coarsening dendritic grains and equiaxed recrystallized grains, respectively. The FSW-welded joint consists of the weld nugget zone, thermo-mechanically affected zone (TMAZ), and HAZ. In the weld nugget zone, a micro-scaled sub-grain structure is the main microstructure characteristic. The TMAZ and HAZ are both characterized by coarsened aging precipitates and elongated deformed grains. The excellent FSW welding properties are attributed to the preservation of the working structures and homogenous chemical compositions.

Lei, Xuefeng; Deng, Ying; Yin, Zhimin; Xu, Guofu

2014-06-01

199

Reflective License Plate Material. Evaluation of Conspicuity and Legibility Performance for a Standard License Plate Configuration Using Beads on Paint versus Reflective Sheeting.  

National Technical Information Service (NTIS)

The literature on nighttime conspicuity (visibility) and legibility of non-reflectorized and reflectorized license plates and their accident reduction potential, safety and other benefits was reviewed. A nighttime field study using 20 young subjects using...

H. T. Zwahlen

1991-01-01

200

A Statistical Comparison of Analyst Accuracy and Speed in Counting Standard Methods Agar Plates Within Selected Colony Count Ranges.  

National Technical Information Service (NTIS)

Agar plates, prepared from serially diluted food homogenate and containing from 30-300 colonies per plate, are used by food microbiology testing laboratories to estimate the microbial population of food samples. Six analysts counted plates with 0-<400 col...

J. T. Fruin T. M. Hill J. B. Clarke J. L. Fowler

1976-01-01

201

Angular shear plate  

DOEpatents

One or more disc-shaped angular shear plates each include a region thereon having a thickness that varies with a nonlinear function. For the case of two such shear plates, they are positioned in a facing relationship and rotated relative to each other. Light passing through the variable thickness regions in the angular plates is refracted. By properly timing the relative rotation of the plates and by the use of an appropriate polynomial function for the thickness of the shear plate, light passing therethrough can be focused at variable positions.

Ruda, Mitchell C. (Tucson, AZ); Greynolds, Alan W. (Tucson, AZ); Stuhlinger, Tilman W. (Tucson, AZ)

2009-07-14

202

Evaluation of brush plated alloys as substitutes for tank plated hard chromium  

SciTech Connect

This paper summarizes results obtained from a test program conducted in cooperation with Tinker Air Force Base (TAFB) in 1993 for the purpose of evaluating the potential of using brush plated alloys as replacements for tank plated hard chromium which is used in the overhaul of jet engines. Tank plating is energy expensive and generates waste products in several of the plating steps. Test specimens used in this study were fabricated from carbon steel, chromium-based stainless steel, and nickel-based stainless steel. Baseline specimens were tank plated with hard chromium or with a soft nickel capped with hard chromium. The specimens were tested for fatigue, thickness, microhardness, Taber wear, and Falex pin and vee block wear. All test were conducted in accordance with standard procedures of the American Society for Testing and Materials (ASTM). Test results obtained from the baseline specimens were compared with those obtained from specimens which had been coated with the three brush plated layered alloy solutions used in this evaluation. Results of this study show that brush plated alloy coatings appear promising as alternatives to tank plated hard chromium. Some data quality problems were encountered during testing, so at this time, definitive statements concerning the use of brush plating alloys as an acceptable alternative to tank plated hard chromium in critical TAFB maintenance, cannot be made. Although these tests results are not positive for TAFB`s operation, users of hard chromium tank plating with less critical applications may find brush plated coatings a suitable alternative. 1 ref.

Durham, H.B. [Environmental Protection Agency, Cincinnati, OH (United States); Hooper, A.M. [Foster Wheeler USA Process Plants Division, Clinton, NY (United States)

1995-11-01

203

Inelastic initial local buckling of skew thin thickness-tapered plates with and without intermediate supports using the isoparametric spline finite strip method  

Microsoft Academic Search

In this paper, skew isotropic plates subjected to in-plane loadings are analyzed using a stability analysis based on the isoparametric spline finite strip method, which includes inelasticity. Using this method, the initial inelastic local buckling of skew plates with or without intermediate line supports is studied based on Ramberg–Osgood representation of the stress–strain curve using the deformation theory of plasticity.

S. Lotfi; M. Azhari; A. Heidarpour

2011-01-01

204

The effect of current density and thickness of the active mass upon the corrosion rate of the spines of lead-acid battery plates  

NASA Astrophysics Data System (ADS)

The effect of current density and the thickness of the active mass upon the corrosion of the spines of tubular lead-acid batteries has been determined by measuring the corrosion rate by the weight loss method. The presence of antimony in the alloy decreases the overvoltage of the corrosion reaction. Study of electrodes of different active mass layer thickness shows that with increase in thickness the corrosion rate decreases. If the thickness is above 3 mm, the corrosion rate remains constant, and is affected only by the nature of the alloy. The density of the active mass does not affect the corrosion behaviour of the electrodes. The experimental results confirm the validity of the oxygen corrosion model.

Rogatchev, T.; Papazov, G.; Pavlov, D.

205

High-temperature crack-arrest behavior in 152-mm-thick SEN wide plates of quenched and tempered A 533 grade B class 1 steel  

Microsoft Academic Search

The Heavy-Section Steel Technology (HSST) Program at the Oak Ridge National Laboratory, under the sponsorship of the US Nuclear Regulatory Commission, is conducting analytical and experimental studies aimed at understanding the circumstances that would initiate the growth of an existing crack in a reactor pressure vessel and the conditions that would lead to arrest of a propagating crack. HSST wide-plate

D. J. Naus; J. Keeney-Walker; B. R. Bass; S. E. Bolt; R. J. Fields; R. deWit; S. R. Low

1989-01-01

206

Split-Thickness Skin Grafts Remain the Gold Standard for the Closure of Large Acute and Chronic Wounds  

PubMed Central

Healing large chronic and acute wounds is a challenging task for wound care providers. It requires numerous visits and frequent dressing changes and often involves expensive therapeutic modalities. Our primary and ultimate goal is to heal these wounds as quickly as possible. In a prepared wound bed, covered with granulation tissue and free of infection, skin graft is the gold standard procedure to achieve this goal. One should keep in mind that not all patients are good candidates for surgery.

Simman, Richard; Phavixay, Laemthong

2012-01-01

207

Topology optimum design of loading plate in fuselage flutter model  

Microsoft Academic Search

Loading plate in fuselage flutter model is a thin-walled plate which is divided into regions with different thickness, so the design and manufacture is a difficult job. In this paper, topology optimum design of loading plate in fuselage flutter model for frequencies is presented. A thin-walled plate of variable thickness is converted to a constant thickness plate with holes. The

Yang Xuyin; Yang Rui; Wang Xianlin

2009-01-01

208

Coracoid bone graft osteolysis after Latarjet procedure: A comparison study between two screws standard technique vs mini-plate fixation  

PubMed Central

Aims: One of the reason for Latarjet procedure failure may be coracoid graft osteolysis. In this study, we aimed to understand if a better compression between the coracoid process and the glenoid, using a mini-plate fixation during the Latarjet procedure, could reduce the amount of coracoid graft osteolysis. Materials and Methods: A computed tomography scan analysis of 26 prospectively followed-up patients was conducted after modified Latarjet procedure using mini-plate fixation technique to determine both the location and the amount of coracoid graft osteolysis in them. We then compared our current results with results from that of our previous study without using mini-plate fixation to determine if there is any statistical significant difference in terms of corcacoid bone graft osteolysis between the two surgical techniques. Results: The most relevant osteolysis was represented by the superficial part of the proximal coracoid, whereas the deep part of the proximal coracoid graft is least involved in osteolysis and has best bone healing. The current study showed a significant difference only for the deep part of the distal coracoid with our previous study (P < 0.01). Discussion: To our knowledge, there are no studies in literature that show the causes of coracoid bone graft osteolysis after Latarjet procedure. Conclusion: Our study suggests that there is a significant difference only for the deep part of the distal coracoid in terms of osteolysis. At clinical examination, this difference did not correspond with any clinical findings. Level of Evidence: Level 4. Clinical Relevance: Prospective case series, Treatment study.

Giacomo, Giovanni Di; Costantini, Alberto; de Gasperis, Nicola; De Vita, Andrea; Lin, Bernard K. H.; Francone, Marco; Beccaglia, Mario A. Rojas; Mastantuono, Marco

2013-01-01

209

Locking Effects for the Reissner-Mindlin Plate Model.  

National Technical Information Service (NTIS)

We analyze the robustness of various standard finite element schemes for the Reissner-Mindlin plate and obtain asymptotic convergence estimates that are uniform in terms of the thickness d. We identify h version schemes that show locking, i.e. for which t...

M. Suri I. Babuska C. Schwab

1992-01-01

210

Hypervelocity plate acceleration  

SciTech Connect

Shock tubes have been used to accelerate 1.5-mm-thick stainless steel plates to high velocity while retaining their integrity. The fast shock tubes are 5.1-cm-diameter, 15.2-cm-long cylinders of PBX-9501 explosive containing a 1.1-cm-diameter cylindrical core of low-density polystyrene foam. The plates have been placed directly in contact with one face of the explosive system. Plane-wave detonation was initiated on the opposite face. A Mach disk was formed in the imploding styrofoam core, which provided the impulse required to accelerate the metal plate to high velocity. Parametric studies were made on this system to find the effect of varying plate metal, plate thickness, foam properties, and addition of a barrel. A maximum plate velocity of 9.0 km/s has been observed. 6 refs., 17 figs.

Marsh, S.P.; Tan, T.H.

1991-01-01

211

The Fresnel zone plate antenna  

Microsoft Academic Search

The Fresnel zone plate, a planar device producing lens-like focusing and imaging of electromagnetic waves, is introduced. Compared to lenses, the zone plate offers advantages in terms of simplicity (flat construction, no curvature), reduced thickness, weight, absorption loss and cost. The main disadvantage of the zone plates is a reduced efficiency compared to a lens; a quarter-wave correction gives 81

James C. Wiltse; James E. Garrett

1991-01-01

212

Channel plate for DNA sequencing  

DOEpatents

This invention is a channel plate that facilitates data compaction in DNA sequencing. The channel plate has a length, a width and a thickness, and further has a plurality of channels that are parallel. Each channel has a depth partially through the thickness of the channel plate. Additionally an interface edge permits electrical communication across an interface through a buffer to a deposition membrane surface. 15 figs.

Douthart, R.J.; Crowell, S.L.

1998-01-13

213

Channel plate for DNA sequencing  

DOEpatents

This invention is a channel plate that facilitates data compaction in DNA sequencing. The channel plate has a length, a width and a thickness, and further has a plurality of channels that are parallel. Each channel has a depth partially through the thickness of the channel plate. Additionally an interface edge permits electrical communication across an interface through a buffer to a deposition membrane surface.

Douthart, Richard J. (Richland, WA); Crowell, Shannon L. (Eltopia, WA)

1998-01-01

214

Standardizing  

NSDL National Science Digital Library

This page, created by Statisical Literacy.com, contains a short article on Simpson'ÃÂÃÂs Paradox with an example of how standardizing changes the results. It also contains links to other "real world" articles on Simpson'ÃÂÃÂs Paradox, including a newspaper article illustrating that this topic is timely. The site features a few graphs to help better represent the concept. Overall, this is a brief but useful explanation of this concept.

2009-02-04

215

Microsphere plate electron multiplier: measurements and modeling  

NASA Astrophysics Data System (ADS)

Microsphere plates (MSPs), a new type of electron multiplier, consisting of sintered disks of glass beads, have recently become available from El-Mul Technologies Ltd. The principles of MSP operation are similar to those of microchannel plates (MCPs). This paper reports a survey of the gain, resistance, dark noise, count rate capability, charge abstraction lifetime, and image characteristics of a number of standard 33 mm diameter microsphere plates (of thickness 0.7 and 1.4 mm), operated both singly and as two-stage multipliers. We also describe a simple Monte-Carlo model of MSP operation, which enables us to estimate numerically a number of MSP characteristics, including (1) output pulse height distributions (PHDs), (2) output electron spatial and energy distributions, and (3) transit time distributions.

Tremsin, Anton S.; Pearson, James F.; Lees, John E.; Fraser, George W.

1995-09-01

216

Measuring Metal Thickness With an Electric Probe  

NASA Technical Reports Server (NTRS)

Thickness of metal parts measured from one side with aid of Kelvin probe. Method developed for measuring thickness of end plate on sealed metal bellows from outside. Suitable for thicknesses of few thousandth's of inch (few hundred micrometers). Method also used to determine thickness of metal coatings applied by sputtering, electroplating, and flame spraying.

Shumka, A.

1986-01-01

217

Fracture in plates of finite thickness  

Microsoft Academic Search

Application of the plane theory of elasticity to planar crack or angular corner geometries leads to the concept of stress singularity and stress intensity factor, which are the cornerstone of contemporary fracture mechanics. However, the stress state near an actual crack tip or corner vertex is always three-dimensional, and the meaning of the results obtained within the plane theory of

A. Kotousov

2007-01-01

218

Rigid Projectile Perforation of Target Plates.  

National Technical Information Service (NTIS)

A new model for rigid projectile perforation of target plates is compared with experimental results for many combinations of spherical projectile diameters, target materials, target plate thickness and impact angles. In most cases of importance the model ...

G. Wijk A. Collin

2001-01-01

219

Assessment of shear deformation theories for multilayered composite plates  

NASA Technical Reports Server (NTRS)

A review is made of the different approaches used for modeling multilayered composite plates. Discussion focuses on different approaches for developing two-dimensional shear deformation theories; classification of two-dimensional theories based on introducing plausible displacement, strain and/or stress assumptions in the thickness direction; and first-order shear deformation theories based on linear displacement assumptions in the thickness coordinate. Extensive numerical results are presented showing the effects of variation in the lamination and geometric parameters of simply supported composite plates on the accuracy of the static and vibrational responses predicted by six different modeling approaches (based on two-dimensional shear deformation theories). The standard of comparison is taken to be the exact three-dimensional elasticity solutions. Some of the future directions for research on the modeling of multilayered composite plates are outlined.

Noor, Ahmed K.; Burton, W. Scott

1989-01-01

220

Guided wave signal transport in curved and tapered plates  

NASA Astrophysics Data System (ADS)

A numerical study is presented of the influence of plate curvature and taper on the transport of ultrasound guided wave signals for nondestructive evaluation (NDE) and structural health monitoring (SHM) applications. Model formulations for transmission at sharp transitions in plate curvature and thickness taper are summarized. Results are presented showing that transitions in plate curvature and tapered plate thickness have minimal effect on signal transmission efficiency when associated characteristic dimensions are large compared to plate thickness.

Roberts, R. A.

2013-01-01

221

A Comparison of Third Grade Suburban and Inner City Children's Performance on the Standard Administration of the Peabody Picture Vocabulary Test and the Naming of the Peabody Picture Vocabulary Test Plates.  

ERIC Educational Resources Information Center

Ninety children were administered the Peabody Picture Vocabulary Test (PPVT) with the standardized administration, as well as an elicited word response task of the PPVT Stimulus Plates. The subjects were inner city black (BIC), inner city white (WIC), and middle class white (WMC) children. The data were analyzed to determine consistency of item…

Daniels, Lenore W.; And Others

222

Short communication: Repeatability of differential goat bulk milk culture and associations with somatic cell count, total bacterial count, and standard plate count.  

PubMed

The aims of this study were to assess how different bacterial groups in bulk milk are related to bulk milk somatic cell count (SCC), bulk milk total bacterial count (TBC), and bulk milk standard plate count (SPC) and to measure the repeatability of bulk milk culturing. On 53 Dutch dairy goat farms, 3 bulk milk samples were collected at intervals of 2 wk. The samples were cultured for SPC, coliform count, and staphylococcal count and for the presence of Staphylococcus aureus. Furthermore, SCC (Fossomatic 5000, Foss, Hillerød, Denmark) and TBC (BactoScan FC 150, Foss) were measured. Staphylococcal count was correlated to SCC (r=0.40), TBC (r=0.51), and SPC (r=0.53). Coliform count was correlated to TBC (r=0.33), but not to any of the other variables. Staphylococcus aureus did not correlate to SCC. The contribution of the staphylococcal count to the SPC was 31%, whereas the coliform count comprised only 1% of the SPC. The agreement of the repeated measurements was low. This study indicates that staphylococci in goat bulk milk are related to SCC and make a significant contribution to SPC. Because of the high variation in bacterial counts, repeated sampling is necessary to draw valid conclusions from bulk milk culturing. PMID:20494165

Koop, G; Dik, N; Nielen, M; Lipman, L J A

2010-06-01

223

Propeller induced hull plate vibrations  

NASA Astrophysics Data System (ADS)

The response of a fluid loaded plate is derived as function of the incident pressure in the fluid. The results are compared with full scale measurements made in the aft peak tank on a ship. Propeller induced pressure and hull plate velocity were measured with flush-mounted hydrophones and accelerometers. It is found that for a typical aft body construction the boundaries of the plate elements can be assumed to be simply supported. The plate model agrees well with full scale measurements down to 40 Hz. Below this frequency global vibrations determine the response of the hull. Both theoretical and experimental results indicate that the field induced by the vibrating plate elements can be considerable. The response of a plate can be decreased if the width of the plate is decreased or the plate thickness increased.

Nilsson, A. C.

1980-04-01

224

Plate motion  

SciTech Connect

The motion of tectonic plates on the earth is characterized in a critical review of U.S. research from the period 1987-1990. Topics addressed include the NUVEL-1 global model of current plate motions, diffuse plate boundaries and the oceanic lithosphere, the relation between plate motions and distributed deformations, accelerations and the steadiness of plate motions, the distribution of current Pacific-North America motion across western North America and its margin, plate reconstructions and their uncertainties, hotspots, and plate dynamics. A comprehensive bibliography is provided. 126 refs.

Gordon, R.G. (USAF, Geophysics Laboratory, Hanscom AFB, MA (United States))

1991-01-01

225

Plate Tectonics  

NSDL National Science Digital Library

Students will go over the main points of plate tectonics, including the theory of continental drift, different types of plate boundaries, seafloor spreading, and convection currents. We have been spending time learning about plate tectonics. We have discussed the theory of continental drift, we have talked about the different types of plate boundaries, we have also learned about seafloor spreading and convection currents. Plate Boundary Diagram Now is your chance ...

Rohlfing, Mrs.

2011-02-03

226

Plate tectonic modelling: virtual reality with GMAP 1 GMAP Standard is available as a freeware on http:\\/\\/www.ngu.no\\/geophysics 1  

Microsoft Academic Search

Palaeogeographic reconstructions have been an integral part of global tectonic research since the advent of the plate tectonic paradigm, and GMAP is a state of the art computer program which performs all processing and plotting tasks associated with the generation of palaeogeographic reconstructions and plate tectonic modelling. GMAP is menu-driven and easy to use; the user is never far removed

Trond Helge Torsvik; Mark Andrew Smethurst

1999-01-01

227

Thermal buckling of functionally graded circular plates based on higher order shear deformation plate theory  

Microsoft Academic Search

In this research, thermal buckling of circular plates compose of functionally graded material (FGM) is considered. Equilibrium and stability equations of a FGM circular plate under thermal loads are derived, based on the higher order shear deformation plate theory (3rd order plate theory). Assuming that the material properties vary as a power form of the thickness coordinate variable z and

M. M. Najafizadeh; H. R. Heydari

2004-01-01

228

Sub-Plate Overlap Code Documentation  

NASA Technical Reports Server (NTRS)

An expansion of the plate overlap method of astrometric data reduction to a single plate has been proposed and successfully tested. Each plate is (artificially) divided into sub-plates which can then be overlapped. This reduces the area of a 'plate' over which a plate model needs to accurately represent the relationship between measured coordinates and standard coordinates. Application is made to non-astrographic plates such as Schmidt plates and to wide-field astrographic plates. Indeed, the method is completely general and can be applied to any type of recording media.

Taff, L. G.; Bucciarelli, B.; Zarate, N.

1997-01-01

229

Plate Tectonics  

NSDL National Science Digital Library

In this activity students use data from underwater earthquakes to outline the location of plate boundaries. Data from the Northeast Pacific, eastern Equatorial Pacific, and North Atlantic are examined in more detail. Background information on plate tectonics is provided.

2002-01-01

230

Fuel cell end plate structure  

DOEpatents

The end plates (16) of a fuel cell stack (12) are formed of a thin membrane. Pressure plates (20) exert compressive load through insulation layers (22, 26) to the membrane. Electrical contact between the end plates (16) and electrodes (50, 58) is maintained without deleterious making and breaking of electrical contacts during thermal transients. The thin end plate (16) under compressive load will not distort with a temperature difference across its thickness. Pressure plate (20) experiences a low thermal transient because it is insulated from the cell. The impact on the end plate of any slight deflection created in the pressure plate by temperature difference is minimized by the resilient pressure pad, in the form of insulation, therebetween.

Guthrie, Robin J. (East Hartford, CT); Katz, Murray (Newington, CT); Schroll, Craig R. (Glastonbury, CT)

1991-04-23

231

Plate Tectonics  

NSDL National Science Digital Library

This interactive Flash explores plate tectonics and provides an interactive map where users can identify plate boundaries with name and velocities as well as locations of earthquakes, volcanoes, and hotspots. The site also provides animations and supplementary information about plate movement and subduction. This resource is a helpful overview or review for introductory level high school or undergraduate physical geology or Earth science students.

Smoothstone; Company, Houghton M.

232

Plate Tectonics  

NSDL National Science Digital Library

Create a poster all about Plate Tectonics! Directions: Make a poster about Plate Tectonics. (20 points) Include at least (1) large picture (15 points) on your poster complete with labels of every part (10 points). (15 points) Include at least three (3) facts about Plate Tectonics. (5 points ...

Walls, Mrs.

2011-01-30

233

Tectonic Plates and Plate Boundaries  

NSDL National Science Digital Library

This interactive activity adapted from NASA features world maps that identify different sections of the Earth's crust called tectonic plates. The locations of different types of plate boundaries are also identified, including convergent, divergent, and transform boundaries.

Foundation, Wgbh E.

2005-12-17

234

Shear Effect Factor for Mindlin Plate Buckling.  

National Technical Information Service (NTIS)

Recent buckling studies by the first author and his associates on circular and rectangular plates indicate a link between the thin plate and thick plate buckling solutions. Such a link is well-known in the elastic buckling loads of Euler's flexural column...

C. M. Wang S. Kitipornchai Y. Xiang

1994-01-01

235

Thick DGP braneworlds  

SciTech Connect

We study Dvali-Gabadadze-Porrati (DGP) braneworlds with finite thickness. In respect to the standard (thin) DGP Friedmann equation, finite thickness of the brane causes a subtle modification of the cosmological equations that can lead to significant physical consequences. The resulting cosmology is governed by two length scales which are associated with the brane thickness and with the crossover length, respectively. In this setup both early inflation and late-time acceleration of the expansion are a consequence of the 5D geometry. At early times, as well as at late times, 5D effects become dominant (gravity leaks into the extra dimension), while, at intermediate times, gravity is effectively 4D due to nontrivial physics occurring in standard (thin) DGP scenarios.

Quiros, Israel [Departamento de Fisica, Universidad Central de Las Villas, 54830 Santa Clara (Cuba); Matos, Tonatiuh [Departamento de Fisica, Centro de Investigacion y de Estudios Avanzados del IPN, A.P. 14-740, 07000 Mexico D.F. (Mexico)

2008-11-15

236

Plate perforation by eroding rod projectiles  

Microsoft Academic Search

The penetration and perforation of stationary, oblique steel plates by hypervelocity tungsten-alloy projectiles is examined here. Simulations have been performed for L\\/D 10 projectiles against one- and two-plate target configurations. The plate thickness-to-rod diameter ratio t\\/D varied slightly, as did the plate spacing-to-plate thickness ratio tgap\\/t. For all simulations, t\\/D?[1.2,1.6] and tgap\\/t?[0.7,1]. Normalized line-of-sight perforation is one measure of performance,

D. J. Gee

2003-01-01

237

Pixelated neutron image plates  

NASA Astrophysics Data System (ADS)

Neutron image plates (NIPs) have found widespread application as neutron detectors for single-crystal and powder diffraction, small-angle scattering and tomography. After neutron exposure, the image plate can be read out by scanning with a laser. Commercially available NIPs consist of a powder mixture of BaFBr : Eu2+ and Gd2O3 dispersed in a polymer matrix and supported by a flexible polymer sheet. Since BaFBr : Eu2+ is an excellent x-ray storage phosphor, these NIPs are particularly sensitive to ggr-radiation, which is always present as a background radiation in neutron experiments. In this work we present results on NIPs consisting of KCl : Eu2+ and LiF that were fabricated into ceramic image plates in which the alkali halides act as a self-supporting matrix without the necessity for using a polymeric binder. An advantage of this type of NIP is the significantly reduced ggr-sensitivity. However, the much lower neutron absorption cross section of LiF compared with Gd2O3 demands a thicker image plate for obtaining comparable neutron absorption. The greater thickness of the NIP inevitably leads to a loss in spatial resolution of the image plate. However, this reduction in resolution can be restricted by a novel image plate concept in which a ceramic structure with square cells (referred to as a 'honeycomb') is embedded in the NIP, resulting in a pixelated image plate. In such a NIP the read-out light is confined to the particular illuminated pixel, decoupling the spatial resolution from the optical properties of the image plate material and morphology. In this work, a comparison of experimentally determined and simulated spatial resolutions of pixelated and unstructured image plates for a fixed read-out laser intensity is presented, as well as simulations of the properties of these NIPs at higher laser powers.

Schlapp, M.; Conrad, H.; von Seggern, H.

2004-09-01

238

Ballistic Limit of CFRP Plates  

NASA Astrophysics Data System (ADS)

JAXA has carried out the hypervelocity impact tests of carbon fiber reinforced plastic (CFRP) plates together with University of Padova. Quasi-isotropic CFRP plates of 2.3, 3.5, and 4.7 mm in thickness were tested. Aluminum sphere of 0.8 to 2.9 mm in diameter was used as projectiles. With a two-stage light gas gun, the projectile was launched with a velocity range of 2 to 5 km/sec in the normal direction to the CFRP plate. Since the perforated hole and the crater on the CFRP plate after the impact are filled with flakes of the carbon fiber, it is difficult to determine the perforation of the projectile. Therefore, whether the projectile perforated the CFRP plate or not was decided by the craters on a copper plate installed behind the CFRP plate. After the impact, peeling along the fiber direction was observed on the surface of the CFRP plate. Moreover, internal delamination was generated near the surface. Finally, a ballistic limit equation of CFRP plates of 2 to 5 mm in thickness was calculated on the basis of the Cour-Palais equation. The ballistic limit equation was in good agreement with the test results.

Higashide, Masumi; Nagao, Yosuke; Kibe, Seishiro; Francesconi, Alessandro; Pavarin, Daniele

239

Strap grid tubular plate—a new positive plate for lead-acid batteries. Processes of residual sulphation of the positive plate  

NASA Astrophysics Data System (ADS)

For almost a century now the tubular plate design has been based on cylindrical tubes and spines. The contact surface between the positive active mass (PAM) and the spine is small, which results in high polarisation of the plate at high discharge currents and low power output of the cell. In an attempt to eliminate these disadvantages, the shape of the tubes has been changed to flattened elliptic and the spines have been replaced by strap grids. The thickness of this new type of tubular plate, strap grid tubular plate (SGTP), is between 3 and 5 mm. Batteries with tubular plates of the new design (SGTP batteries) can be used in electric vehicle (EV) and photovoltaic (PV) system applications. This paper presents results of SGTP battery tests according to the European standards for EV, hybrid electric vehicle (HEV) and photovoltaic (PV) system batteries. SGTP batteries have a cycle life of 1000 ECE-15-EV cycles, 6000 ECE-HEV cycles and more than eight gross PV cycles. The optimum battery charge algorithm for VRLA batteries with strap grid tubular plates has been established and the mechanism of disintegration of the positive active mass has been disclosed. The following phenomena are responsible for the decline in capacity of the positive plates. First, when the PAM is built up of globules adhering closely to each other, a strong skeleton with thick aggregates (branches) with a membrane surface is formed. The surface layer of the branches impedes the access of H 2O and H 2SO 4 to their interior thus reducing the utilisation of the PAM. Besides, internal stresses are created in the aggregates, which cause them to crack. Secondly, when the PAM is built up of individual agglomerates with micropores in between, a porous mass with large surface is formed. The tubes keep the aggregates together and prolong the cycle life of the battery. During discharge, the contacts between the aggregates weaken and the capacity declines. Third, during discharge, the H 2SO 4 concentration in the pores of the plate inner layers (close to the straps) increases. In concentrated H 2SO 4 solution the solubility of PbSO 4 crystals decreases. This slows down the rate of oxidation of PbSO 4 to PbO 2. Some parts of the PbSO 4 crystals in the PAM of the charged plate remain unoxidised (residual sulphation). Thus, the capacity of the plate is lower. Strap corrosion is the phenomenon that may limit the cycle life of SGT plates.

Pavlov, D.; Papazov, G.; Monahov, B.

240

Effect of Chrome Plating on the Wear Characteristics and Ballistic Performance in the 155-mm M198 Artillery System.  

National Technical Information Service (NTIS)

Wear tests were conducted on both a 0.25-mm thick, chrome-plated M199 cannon for the M198 artillery system and the standard M199 steel cannon. During testing, M483A1 projectiles were fired from both tubes with the high zone propelling charge M203. After e...

A. C. Vallado J. A. Lannon

1981-01-01

241

Shear deflection of anisotropic plate  

NASA Astrophysics Data System (ADS)

In the thin plate theory, shear deformation is neglected. This theory is unreliable for plates of considerable thickness in the vicinity of the point of application of load, and sandwich plates with shear rigidity which is very low compared with bending rigidity. A widely accepted theory which includes the effects of shear deformation was developed by Reissner and Mindlin. In recent years, composite materials have been widely employed as structure elements. Plates of composite material are characterized by strong anisotropy and low out-of-plane shear rigidity. This paper provides a convenient representation for the stiffness matrix of the finite element in order to analyze a sandwich plate with an anisotropic face plate and core. The formulation is based on the nonconforming element of Zienkiewicz (1977) and is obtained with a modified stiffness matrix in the condition in which the out-of-plane shear strain is constant in two directions within an element.

Katori, Hiroaki; Nishimura, Tohru

1992-01-01

242

Piezoactuation of sandwich plates with viscoelastic cores  

Microsoft Academic Search

Experimental and analytical validations of a Galerkin analysis of sandwich plates is presented in this paper. The 3-layered sandwich plate specimen consists of isotropic face-plates with surface bonded piezo-electric patch actuators, and a viscoelastic core. The experimental validation is conducted by testing sandwiched plates that are 67.31 cm (26.5') long, 52.07 cm (20.5') wide and nominally 0.16 cm (1\\/16') thick.

Gang Wang; Norman M. Wereley

1999-01-01

243

Plating Processes Utilizing High Intensity Acoustic Beams  

NASA Technical Reports Server (NTRS)

A system and a method for selective plating processes are disclosed which use directed beams of high intensity acoustic waves to create non-linear effects that alter and improve the plating process. The directed beams are focused on the surface of an object, which in one embodiment is immersed in a plating solution, and in another embodiment is suspended above a plating solution. The plating processes provide precise control of the thickness of the layers of the plating, while at the same time, in at least some incidents, eliminates the need for masking.

Oeftering, Richard C. (Inventor); Denofrio, Charles (Inventor)

2002-01-01

244

Consecutive plate acoustic suppressor apparatus and methods  

NASA Technical Reports Server (NTRS)

An apparatus and method for suppressing acoustic noise utilizes consecutive plates, closely spaced to each other so as to exploit dissipation associated with sound propagation in narrow channels to optimize the acoustic resistance at a liner surface. The closely spaced plates can be utilized as high temperature structural materials for jet engines by constructing the plates from composite materials. Geometries of the plates, such as plate depth, shape, thickness, inter-plate spacing, arrangement, etc., can be selected to achieve bulk material-like behavior.

Doychak, Joseph (inventor); Parrott, Tony (inventor)

1992-01-01

245

Consecutive plate acoustic suppressor apparatus and methods  

NASA Astrophysics Data System (ADS)

An apparatus and method for suppressing acoustic noise utilizes consecutive plates, closely spaced to each other so as to exploit dissipation associated with sound propagation in narrow channels to optimize the acoustic resistance at a liner surface. The closely spaced plates can be utilized as high temperature structural materials for jet engines by constructing the plates from composite materials. Geometries of the plates, such as plate depth, shape, thickness, inter-plate spacing, arrangement, etc., can be selected to achieve bulk material-like behavior.

Doychak, Joseph; Parrott, Tony

1992-10-01

246

Plate Tectonics  

NSDL National Science Digital Library

In this lesson, students are introduced to the theory of plate tectonics and explore how the theory was developed and supported by evidence. Through class discussion, videos, and activities, students seek connections between tectonic activity and geologic features and investigate how the theory of plate tectonics evolved.

2006-01-01

247

Plate Tectonics  

NSDL National Science Digital Library

This site contains 25 questions on the topic of plate tectonics, which covers the development of the theory, crustal movements, geologic features associated with tectonics, and plate boundaries (convergent, divergent, transform). This is part of the Principles of Earth Science course at the University of South Dakota. Users submit their answers and are provided immediate verification.

Heaton, Timothy

248

Statistical tests of additional plate boundaries from plate motion inversions  

Microsoft Academic Search

The application of the F-ratio test, a standard statistical technique, to the results of relative plate motion inversions has been investigated. The method tests whether the improvement in fit of the model to the data resulting from the addition of another plate to the model is greater than that expected purely by chance. This approach appears to be useful in

Seth Stein; R. G. Gordon

1984-01-01

249

Correlations of skin fold thickness and validation of prediction equations using DEXA as the gold standard for estimation of body fat composition in Pakistani children  

PubMed Central

Objective To determine the correlation between dual energy X-ray absorptiometry (DEXA) and skin fold thickness (SKF) equations for estimation of body fat (BF) composition in secondary school children and validation of prediction equations by Slaughter, Goran and Dezenberg. Design Cross sectional analytical study. Setting Joint Commission for International Accredited (JCIA) tertiary care hospital of Karachi, Pakistan from January 2010 to May 2010. Participants The study was approved by the Hospital's ethical review committee. Written and verbal consents were obtained from principals of two schools and parents of 99 children (mean age of 14±1.89?years; min–max 9–19?years; 54 men and 45 women) accrued in study. DEXA scan was acquired and SKF was measured at angle of the scapula, iliac crest and mid-arm for bicep and tricep skin folds using Holtain Callipers. Correlations were established between estimated fat mass (FM) and per cent BF (%BF) calculated by DEXA and those predicted by prediction equations. On obtaining significant correlation of >0.5, overall accuracy, precision and bias was calculated. Results There was an overall increased adiposity in females with FM of 3.57?kg and %BF 6.2% higher than male counterparts (p<0.05). Slaughter equation predicted %BF accurately with overall high accuracy, minimal bias and with good precision with DEXA. Dezenberg and Goran equations had significant bias in prediction of FM which was statistically significant with low level of accuracy of the Goran equation. Conclusions We conclude that Slaughter equation for estimating %BF showed reasonable validation with DEXA. Nevertheless further studies with consideration for maturity and ethnicity are warranted for better results. However, for estimation of FM, previously formulated equations by Goran and Dezenberg showed significant difference in our population. We do recommend further studies for developing and validation of skin fold equations specific to Pakistani paediatric population.

Hussain, Zainab; Jafar, Tazeen; Zaman, Maseeh uz; Parveen, Riffat; Saeed, Farzan

2014-01-01

250

Comparison of a standard fully covered stent with a super-thick silicone-covered stent for the treatment of refractory esophageal benign strictures: A prospective multicenter study  

PubMed Central

Background Some esophageal strictures resist endoscopic treatments. There is a need for new treatments, such as specifically designed stents. Objective Our study sought to compare the results achieved with a standard, fully covered metallic stent (FCMS) and those achieved using a stent designed specifically for benign strictures (BS-FCMS). Patients and methods The study used a prospective, multicenter, controlled design, with patients recruited from tertiary referral centers. Patients with refractory esophageal strictures were included. Standard FCMS were used in group 1 (N?=?24), and BS-FCMS were used in group 2 (N?=?17). Patients were followed for 24 months after stent removal. The main outcomes measured were stricture resolution rate, 24 months’ recurrence rate and stent-related morbidity. Results Early stent migrations occurred in one (4.1%) patient from group 1 and five (29.4%) from group 2 (p?

Chaput, Ulriikka; Heresbach, Denis; Audureau, Etienne; Vanbiervliet, Geoffroy; Gaudric, Marianne; Bichard, Philippe; Bauret, Paul; Coumaros, Dimitri; Ponchon, Thierry; Fumex, Fabien; Bensoussan, Emmanuel; Lamouliatte, Herve; Chryssostalis, Ariane; Robin, Francoise

2013-01-01

251

Ballistic Limit of CFRP Plates  

Microsoft Academic Search

JAXA has carried out the hypervelocity impact tests of carbon fiber reinforced plastic (CFRP) plates together with University of Padova. Quasi-isotropic CFRP plates of 2.3, 3.5, and 4.7 mm in thickness were tested. Aluminum sphere of 0.8 to 2.9 mm in diameter was used as projectiles. With a two-stage light gas gun, the projectile was launched with a velocity range

Masumi Higashide; Yosuke Nagao; Seishiro Kibe; Alessandro Francesconi; Daniele Pavarin

2009-01-01

252

Carotid wall elastography to assess midterm vascular dysfunction secondary to intrauterine growth restriction: feasibility and comparison with standardized intima-media thickness.  

PubMed

Several studies have suggested that intrauterine growth restriction (IUGR) increases the risk of cardiovascular disease and early atherosclerosis. Early detection of arteriopathy is essential to early intervention. Although arterial intima-media thickness (IMT) is considered an index of subclinical atherosclerosis in the adult, its validity in pediatric patients may be limited. We have recently introduced a novel imaging-based biomarker (ImBioMark) to assess intrinsic mechanical features of the arterial wall from B-mode ultrasound data. The aim of the work described here was to evaluate the potential of ImBioMark in investigation of cardiovascular health status at the level of the common carotid artery (CCA) in adolescents born after IUGR. We also compared ImBioMark results with automated IMT measurements, a well-established biomarker used in clinical practice and research. The potential sequelae of IUGR on the CCA were examined in a group of adolescents in comparison with healthy controls. Patients with IUGR (n = 7) were 13.85 ± 0.46 y old; the healthy controls (n = 7) were 14.58 ± 0.80 y old (p = 0.058). Cine loops of the CCA B-mode data were digitally recorded, and the arterial elastic modulus was estimated a posteriori with ImBioMark. IMT of the CCA was automatically calculated using QLAB software (Philips, Andover, MA, USA). All patients had been evaluated in utero in our fetal echocardiographic laboratory. ImBioMark detected a significant increase in CCA stiffness in patients with IUGR as compared with healthy controls: elastic modulus = 90.74 ± 11.86 versus 61.30 ± 15.94 kPa, respectively (p = 0.002). There was, however, no significant difference between patients with IUGR and controls in IMT (0.483 ± 0.067 versus 0.476 ± 0.051 mm, respectively, p = 0.831). The impact of IUGR on CCA wall dynamics was confirmed by ImBioMark. The apparent limitation of IMT measurement in this cohort may be the result of geometric arterial changes, that is, the expected thickening, below the level of detection at this age. As early detection of vascular modulation is essential to early intervention in a population at risk, we now intend to extend ImBioMark to investigate larger pathologic cohorts with various degrees of arteriopathy. PMID:24495436

Maurice, Roch L; Vaujois, Laurence; Dahdah, Nagib; Chibab, Najat; Maurice, Anika; Nuyt, Anne-Monique; Lévy, Emile; Bigras, Jean-Luc

2014-05-01

253

Effective elastic thickness and crustal thickness variations in west central Africa inferred from gravity data  

SciTech Connect

This report uses coherence function analysis of 32,000 gravity and topography points from Cameroon west Africa to determine the relationship between the plate tectonic and flexural rigidity of the lithosphere in terms of the crusts effective elastic thickness.

Poudjom Djomani, Y.H.; Nnange, J.M.; Ebinger, C.J. [Univ. of Leeds (United Kingdom)] [and others] [Univ. of Leeds (United Kingdom); and others

1995-11-10

254

Femoral plating.  

PubMed

We have demonstrated that we are able to meet both trauma and orthopedic goals with immediate plate fixation of femoral fractures in patients with blunt polytrauma. Our femoral fracture mortality rate is less than our predicted institutional mortality rate of patients with comparative injury severity scores. Ipsilateral femoral neck and shaft fractures are easily repaired with femoral plating. Infections, even in open fractures and systemically unstable patients, are rare. Implant failures have been infrequent and are easily reconstructed with intramedullary nails. Knee motion has been restored reliably. Stainless steel DCP plate fixation requires primary bone grafting. Achieving union and subsequent knee rehabilitation often requires that patients remain on crutches for up to 6 months. Our experience with titanium LCDCP plates is preliminary, but we are seeing a significant amount of callus formation and, perhaps, earlier union and bearing weight. PMID:8090475

Riemer, B L; Foglesong, M E; Miranda, M A

1994-10-01

255

Plate Motions  

NSDL National Science Digital Library

To prepare for this exercise students read the Chapter on plate tectonics in their text book. In class, they are given a color isochron map of the sea floor. They are given 4 tasks: Answer basic questions about the timing and rate of opening of the N. and S. Atlantic; Determine what has happened to the oceanic crust that is created on the eastern side of the East Pacific Rise; Determine what type of plate boundary existed on the western edge of the N. America plate before the San Andreas Fault and when this transition occurred; and Reconstruct the motion of the plates over the last 40 Ma assuming that the surface area of the Earth has not changed.

Nunn, Jeffrey

256

Novel Method for Characterizing the Impact Response of Functionally Graded Plates.  

National Technical Information Service (NTIS)

Functionally graded material (FGM) plates are advanced composites with properties that vary continuously through the thickness of the plate. Metal-ceramic FGM plates have been proposed for use in thermal protection systems where a metal-rich interior surf...

R. A. Larson

2008-01-01

257

Factors Affecting Energy Absorption of a Plate during Shock Wave Impact Using a Damage Material Model.  

National Technical Information Service (NTIS)

This thesis examines the influences of five factors on the strain energy at failure of metallic alloy plates during a shock wave impact. The five factors are material type, initial damage, boundary conditions, plate thickness, and plate temperature. The f...

Z. K. Crosby

2010-01-01

258

On a boundary layer phenomenon in Mindlin-Reissner plate theory for laminated circular sector plates  

Microsoft Academic Search

Summary In this article, the edge-zone equation of Mindlin-Reissner plate theory, for composite plates laminated of transversely isotropic layers is studied. Analytical solutions are obtained for both circular sector and completely circular plates with various boundary conditions. The boundary-layer function and its effect on the stresses are numerically studied. Effects of plate thickness and boundary conditions are investigated. The results

A. Nosier; A. Yavari; S. Sarkani

2001-01-01

259

Frequency spectra of beam-plates revisited.  

PubMed

Based on Mindlin's plate theory, the frequency spectra for flexural and thickness-shear vibrations of a finite beam-plate with different combinations of boundary conditions are presented and studied. Comparing them with the dispersion curves of the infinite beam-plate reveals an intrinsic relation between resonant vibration and guided wave propagation. The fundamental frequency spectra, which are for beam-plates with hinged and/or guided edges, are found to play an important role in understanding the spectra of beam-plates with other boundary conditions. PMID:18606431

Guo, Y Q; Chen, W Q; Pao, Y H

2009-01-01

260

The Bending and Stretching of Plates  

NASA Astrophysics Data System (ADS)

Written by one of the world's leading authorities on plate behavior, this study gives a clear physical insight into elastic plate behavior. Small-deflection theory is treated in Part 1 in chapters dealing with basic equations: including thermal effects and multi-layered anisotropic plates, rectangular plates, circular and other shaped plates, plates whose boundaries are amenable to conformal transformation, plates with variable thickness, and approximate methods. Large-deflection theory is treated in Part 2 in chapters dealing with basic equations and exact solutions; approximate methods, including post-buckling behavior; and asymptotic theories for very thin plates, including tension field theory and inextensional theory. The mathematical content is necessarily high, making the style of the book appropriate to engineers and applied mathematicians. E.H. Mansfield is a Fellow of the Royal Society, a founder member of the Fellowship of Engineering, and the author of over 100 publications.

Mansfield, Eric Harold

2005-08-01

261

The Bending and Stretching of Plates  

NASA Astrophysics Data System (ADS)

Written by one of the world's leading authorities on plate behavior, this study gives a clear physical insight into elastic plate behavior. Small-deflection theory is treated in Part 1 in chapters dealing with basic equations: including thermal effects and multi-layered anisotropic plates, rectangular plates, circular and other shaped plates, plates whose boundaries are amenable to conformal transformation, plates with variable thickness, and approximate methods. Large-deflection theory is treated in Part 2 in chapters dealing with basic equations and exact solutions; approximate methods, including post-buckling behavior; and asymptotic theories for very thin plates, including tension field theory and inextensional theory. The mathematical content is necessarily high, making the style of the book appropriate to engineers and applied mathematicians. E.H. Mansfield is a Fellow of the Royal Society, a founder member of the Fellowship of Engineering, and the author of over 100 publications.

Mansfield, Eric Harold

1989-09-01

262

Reliability assessment of different plate theories for elastic wave propagation analysis in functionally graded plates.  

PubMed

The importance of elastic wave propagation problem in plates arises from the application of ultrasonic elastic waves in non-destructive evaluation of plate-like structures. However, precise study and analysis of acoustic guided waves especially in non-homogeneous waveguides such as functionally graded plates are so complicated that exact elastodynamic methods are rarely employed in practical applications. Thus, the simple approximate plate theories have attracted much interest for the calculation of wave fields in FGM plates. Therefore, in the current research, the classical plate theory (CPT), first-order shear deformation theory (FSDT) and third-order shear deformation theory (TSDT) are used to obtain the transient responses of flexural waves in FGM plates subjected to transverse impulsive loadings. Moreover, comparing the results with those based on a well recognized hybrid numerical method (HNM), we examine the accuracy of the plate theories for several plates of various thicknesses under excitations of different frequencies. The material properties of the plate are assumed to vary across the plate thickness according to a simple power-law distribution in terms of volume fractions of constituents. In all analyses, spatial Fourier transform together with modal analysis are applied to compute displacement responses of the plates. A comparison of the results demonstrates the reliability ranges of the approximate plate theories for elastic wave propagation analysis in FGM plates. Furthermore, based on various examples, it is shown that whenever the plate theories are used within the appropriate ranges of plate thickness and frequency content, solution process in wave number-time domain based on modal analysis approach is not only sufficient but also efficient for finding the transient waveforms in FGM plates. PMID:23714123

Mehrkash, Milad; Azhari, Mojtaba; Mirdamadi, Hamid Reza

2014-01-01

263

30 CFR 20.13 - Approval plate.  

Code of Federal Regulations, 2013 CFR

...ELECTRIC MINE LAMPS OTHER THAN STANDARD CAP LAMPS § 20.13 Approval plate. The manufacturer shall attach, stamp, or mold an approval plate on the battery container or housing of each permissible lamp. The plate shall bear the emblem of the...

2013-07-01

264

Stainless steel bipolar plates  

NASA Astrophysics Data System (ADS)

In this research, a specific surface modification technology was developed for stainless steel bipolar plates to obtain a corrosion-resistant oxide film. The surface roughness was measured, and an electron spectroscopy analysis (ESCA) was conducted to verify the chemical composition of the surface layer. From the binding energy of the ESCA spectrum, the amounts of chemical shift were used to identify the major chemical compositions. The thickness of the oxide film was analyzed by auger electron spectroscopy (AES). From the results of the ESCA and AES analyses, the effects of the surface modification on the integrity of the surface were evaluated. Uniform corrosion and localized corrosion tests were also conducted to investigate any improvement on the corrosion characteristics. A single cell was assembled for cell performance tests. The surface of the treated plates was bright and smooth. The ESCA and AES analyses showed that the treated plates had a much higher chrome content. The metallurgical structure was dense with substantially less defects. The chemical and electrochemical properties were more stable. The corrosion rates of the treated plates were also much improved, resulting in better electric conductivity, stable cell performance as well as longer cell life.

Lee, Shuo-Jen; Lai, Jian-Jang; Huang, Ching-Han

265

Musical Plates  

NSDL National Science Digital Library

This on-line project is part of the Center for Improved Engineering and Science Education (CIESE) program. As they complete this series of lessons, students will use real-time data to solve a problem, study the correlation between earthquakes and tectonic plates, and determine whether or not there is a relationship between volcanoes and plate boundaries. Musical Plates has four Core Activities that will teach students how to access and interpret real-time earthquake and volcano data and to how use the information to solve a real-world problem. Each of the core activities is designed to be used in a 45-minute class period. This unit also has three enrichment lessons and a final project lesson that can also be used for assessment.

2007-12-12

266

Bipolar battery plate  

SciTech Connect

A liquid-impermeable plate having throughplate conductivity with essentially zero resistance comprises an insulator sheet having a series of spaced perforations each of which contains a metal element sealingly received into the perforation. A low-cost plate can readily be manufactured by punching a thermoplastic sheet such as polypropylene with a punching tool, filling the apertures with lead spheres having a diameter smaller than the holes but larger than the thickness of the sheet, sweeping excess spheres off the sheet with a doctor blade and then pressing a heated platen onto the sheet to swage the spheres into a cylindrical shape and melt the surrounding resin to form a liquid-impermeable collar sealing the metal into the sheet.

Rowlette, J. J.

1985-09-17

267

Inelastic buckling of plate  

NASA Astrophysics Data System (ADS)

This paper concerns the inelastic stability of a thin plate under in-plane loading. In Love-Kirchhoffs approximation, using Hencky's relations and the Von Mises criterion, yield the particular stress distribution across the plate thickness for elastic and elastic-plastic prestress fields. The principle of virtual work is used to study the equilibrium of the bifurcated solution. This leads to the energy relations where explicit dependence between the stability equation coefficients and the solution is carried out. In the equilibrium equation, two nonquadratic additional terms are obtained which are neglected in the classical equation. Some applications are made using Ramberg-Osgood's formula to show the importance of the additional terms.

Rio, G.

268

Cadmium plating replacements  

NASA Technical Reports Server (NTRS)

The Boeing Company has been searching for replacements to cadmium plate. Two alloy plating systems seem close to meeting the needs of a cadmium replacement. The two alloys, zinc-nickel and tin-zinc are from alloy plating baths; both baths are neutral pH. The alloys meet the requirements for salt fog corrosion resistance, and both alloys excel as a paint base. Currently, tests are being performed on standard fasteners to compare zinc-nickel and tin-zinc on threaded hardware where cadmium is heavily used. The Hydrogen embrittlement propensity of the zinc-nickel bath has been tested, and just beginning for the tin-zinc bath. Another area of interest is the electrical properties on aluminum for tin-zinc and will be discussed. The zinc-nickel alloy plating bath is in production in Boeing Commercial Airplane Group for non-critical low strength steels. The outlook is promising that these two coatings will help The Boeing Company significantly reduce its dependence on cadmium plating.

Nelson, Mary J.; Groshart, Earl C.

1995-01-01

269

Musical Plates: A Study of Plate Tectonics  

NSDL National Science Digital Library

In this project, students use Real-Time earthquake and volcano data from the Internet to explore the relationship between earthquakes, plate tectonics, and volcanoes. There is a teachers guide that explains how to use real time data, and in the same section, there is a section for curriculum standards, Supplement and enrichment activities, and assessment suggestions. Included on this webpage are four core activities, and three enrichment activities, including an activity where the student writes a letter to the president. There is also a link to reference materials that might also interest you and your students.

2007-01-01

270

Assumed strain distributions for a finite strip plate bending element using Mindlin-Reissner plate theory  

NASA Technical Reports Server (NTRS)

A linear finite strip plate element based on Mindlin-Reissner plate theory is developed. The analysis is suitable for both thin and thick plates. In the formulation, new transverse shear strains are introduced and assumed constant in each two-node linear strip. The element stiffness matrix is explicitly formulated for efficient computation and computer implementation. Numerical results showing the efficiency and predictive capability of the element for the analysis of plates are presented for different support and loading conditions and a wide range of thicknesses. No sign of shear locking is observed with the newly developed element.

Chulya, Abhisak; Mullen, Robert L.

1989-01-01

271

On the scaling of the magnetically accelerated flyer plate technique to currents greater than 20 MA  

NASA Astrophysics Data System (ADS)

In this article we discuss scaling the magnetically accelerated flyer plate technique to currents greater than is available on the Z accelerator. Peak flyer plate speeds in the range 7-46 km/s are achieved in pulsed power driven, hyper-velocity impact experiments on Z for peak currents in the range 8-20 MA. The highest (lowest) speeds are produced using aluminum (aluminum-copper) flyer plates. In either case, the =1 mm thick flyer plate is shocklessly accelerated by magnetic pressure to ballistic speed in =400 ns; it arrives at the target with a fraction of material at standard density. During acceleration a melt front, due to resistive heating, moves from the drive-side toward the target-side of the flyer plate; the speed of the melt front increases with increasing current. Peak flyer speeds on Z scale quadratically (linearly) with current at the low (high) end of the range. Magnetohydrodynamic simulation shows that the change in scaling is due to geometric deformation, and that linear scaling continues as current increases. However, the combined effects of shockless acceleration and resistive heating lead to an upper bound on the magnetic field feasible for pulsed power driven flyer plate experiments, which limits the maximum possible speed of a useful flyer plate to < 100 km/s.

Lemke, R. W.; Knudson, M. D.; Cochrane, K. R.; Desjarlais, M. P.; Asay, J. R.

2014-05-01

272

Large dielectric plate antenna charging and protection in space  

Microsoft Academic Search

This paper reports the study of the charging of a large dielectric plate antenna in space. The work presented here consists of three parts. First, the surface charging of the large dielectric plate antenna and its effects due to aurora precipitate electron. The antenna surface could charge to kV magnitude because of its thick dielectric plate, and the charging rate

Wang Li; Liu Yang; Li Kai; Qing Xiaogang

2000-01-01

273

Tectonic Plates and Plate Boundaries  

NSDL National Science Digital Library

Continents were once thought to be static, locked tight in their positions in Earth's crust. Similarities between distant coastlines, such as those on opposite sides of the Atlantic, were thought to be the work of a scientist's overactive imagination, or, if real, the result of erosion on a massive scale. This interactive feature shows 11 tectonic plates and their names, the continents that occupy them, and the types of boundaries between them.

2011-05-09

274

An analytical study on the free vibration of smart circular thin FGM plate based on classical plate theory  

Microsoft Academic Search

Analytical investigation of the free vibration behavior of thin circular functionally graded (FG) plates integrated with two uniformly distributed actuator layers made of piezoelectric (PZT4) material based on the classical plate theory (CPT) is presented in this paper. The material properties of the FG substrate plate are assumed to be graded in the thickness direction according to the power-law distribution

Farzad Ebrahimi; Abbas Rastgo

2008-01-01

275

Tube wall thickness measurement apparatus  

DOEpatents

An apparatus for measuring the thickness of a tube's wall for the tube's entire length and radius by determining the deviation of the tube wall thickness from the known thickness of a selected standard item. The apparatus comprises a base and a first support member having first and second ends. The first end is connected to the base and the second end is connected to a spherical element. A second support member is connected to the base and spaced apart from the first support member. A positioning element is connected to and movable relative to the second support member. An indicator is connected to the positioning element and is movable to a location proximate the spherical element. The indicator includes a contact ball for first contacting the selected standard item and holding it against the spherical element. The contact ball then contacts the tube when the tube is disposed about the spherical element. The indicator includes a dial having a rotatable needle for indicating the deviation of the tube wall thickness from the thickness of the selected standard item.

Lagasse, P.R.

1985-06-21

276

Tube wall thickness measurement apparatus  

DOEpatents

An apparatus for measuring the thickness of a tube's wall for the tube's entire length and circumference by determining the deviation of the tube wall thickness from the known thickness of a selected standard item. The apparatus comprises a base and a first support member having first and second ends. The first end is connected to the base and the second end is connected to a spherical element. A second support member is connected to the base and spaced apart from the first support member. A positioning element is connected to and movable relative to the second support member. An indicator is connected to the positioning element and is movable to a location proximate the spherical element. The indicator includes a contact ball for first contacting the selected standard item and holding it against the spherical element. The contact ball then contacts the tube when the tube is disposed about the spherical element. The indicator includes a dial having a rotatable needle for indicating the deviation of the tube wall thickness from the thickness of the selected standard item.

Lagasse, Paul R. (Santa Fe, NM)

1987-01-01

277

Corrections for Thermal Expansion in Thermal Conductivity Measurement of Insulations Using the High-Temperature Guarded Hot-Plate Method  

NASA Astrophysics Data System (ADS)

The anticipation of recently published European product standards for industrial thermal insulation has driven improvements in high-temperature thermal conductivity measurements in an attempt to obtain overall measurement uncertainties better than 5 % ( k = 2). The two measurement issues that are focused on in this article are the effect of thermal expansion on in situ thickness measurement and on determining the metering area at high temperatures. When implementing in situ thickness measurements, it is vital to correct the thermal expansion of components in a high-temperature guarded hot plate (HTGHP). For example, in the NPL HTGHP this could cause 3.2 % measurement error for a 50 mm thick specimen at 800 °C. The thermal expansion data for nickel 201 measured by NPL are presented, and the effect of this on the metering area of NPL's heater plate (nickel 201) is discussed.

Wu, Jiyu; Morrell, Roger

2012-02-01

278

Free vibration of functionally graded rectangular plates using first-order shear deformation plate theory  

Microsoft Academic Search

The main objective of this research work is to present analytical solutions for free vibration analysis of moderately thick rectangular plates, which are composed of functionally graded materials (FGMs) and supported by either Winkler or Pasternak elastic foundations. The proposed rectangular plates have two opposite edges simply-supported, while all possible combinations of free, simply-supported and clamped boundary conditions are applied

Sh. Hosseini-Hashemi; H. Rokni Damavandi Taher; H. Akhavan; M. Omidi

2010-01-01

279

Properties of the Anisimkin Jr.' modes in quartz plates.  

PubMed

Dispersion curves, surface displacements, and displacement profiles over the plate thickness are numerically calculated for acoustic plate modes, propagating in fused and Y-rotated, X-cut quartz samples with thickness h/lambda in the range 0-4.5 (h, thickness; lambda, wavelength). The Anisimkin Jr.' modes with velocity v(n) close to that of longitudinal bulk wave v(L) and the dominant longitudinal displacement u1 distributed uniformly through the plate thickness are found in quartz crystals with cut angles mu = 120 degrees-140 degrees and plate thickness h/lambda = 0-0.36, 0.94-1.78, 2.32-3.08, and 3.64-4.44. The same modes in fused quartz are not found, except in a narrow region near zero thickness. PMID:17718327

Gulyaev, Yury V

2007-07-01

280

Impact on multilayered composite plates  

NASA Technical Reports Server (NTRS)

Stress wave propagation in a multilayer composite plate due to impact was examined by means of the anisotropic elasticity theory. The plate was modelled as a number of identical anisotropic layers and the approximate plate theory of Mindlin was then applied to each layer to obtain a set of difference-differential equations of motion. Dispersion relations for harmonic waves and correction factors were found. The governing equations were reduced to difference equations via integral transforms. With given impact boundary conditions these equations were solved for an arbitrary number of layers in the plate and the transient propagation of waves was calculated by means of a Fast Fourier Transform algorithm. The multilayered plate problem was extended to examine the effect of damping layers present between two elastic layers. A reduction of the interlaminar normal stress was significant when the thickness of damping layer was increased but the effect was mostly due to the softness of the damping layer. Finally, the problem of a composite plate with a crack on the interlaminar boundary was formulated.

Kim, B. S.; Moon, F. C.

1977-01-01

281

Statistical tests of additional plate boundaries from plate motion inversions  

NASA Technical Reports Server (NTRS)

The application of the F-ratio test, a standard statistical technique, to the results of relative plate motion inversions has been investigated. The method tests whether the improvement in fit of the model to the data resulting from the addition of another plate to the model is greater than that expected purely by chance. This approach appears to be useful in determining whether additional plate boundaries are justified. Previous results have been confirmed favoring separate North American and South American plates with a boundary located beween 30 N and the equator. Using Chase's global relative motion data, it is shown that in addition to separate West African and Somalian plates, separate West Indian and Australian plates, with a best-fitting boundary between 70 E and 90 E, can be resolved. These results are generally consistent with the observation that the Indian plate's internal deformation extends somewhat westward of the Ninetyeast Ridge. The relative motion pole is similar to Minster and Jordan's and predicts the NW-SE compression observed in earthquake mechanisms near the Ninetyeast Ridge.

Stein, S.; Gordon, R. G.

1984-01-01

282

Compressive failure of thick-section composite laminates with and without cutouts subjected to biaxial loading  

NASA Technical Reports Server (NTRS)

The composites studied are fiber composite laminate plates made of carbon fibers and a thermoplastic matrix material. Tests and results are given for: the solution convergence for transverse shear in a clamped plate without cutout under compression; the effects of cutout and laminate thickness on maximum shear in buckling and postbuckling response of a clamped plate under biaxial compression; the effects of cutout and laminate thickness on maximum shear in buckling and postbuckling response of a clamped plate under biaxial compression; and the effects of laminate thickness and cutout of the lowest three eigenvalues of a clamped plate under biaxial compression. Additional test results are given.

Rouxel, L.; Wang, S. S.

1990-01-01

283

Asymmetric flexural vibration and thermoelastic stability of FGM circular plates using finite element method  

Microsoft Academic Search

Here, asymmetric free vibration characteristics and thermoelastic stability of functionally graded circular plates are investigated using finite element procedure. A three-noded shear flexible plate element based on the field-consistency principle is used. Temperature field is assumed to be a uniform distribution over the plate surface and varied in thickness direction only. Material properties are graded in the thickness direction according

T. Prakash; M. Ganapathi

2006-01-01

284

Plate Tectonics II: Plates, plate boundaries, and driving forces  

NSDL National Science Digital Library

The distribution of earthquakes and volcanoes around the world confirmed the theory of plate tectonics first proposed by Wegener. These phenomena also help categorize plate boundaries into three different types: convergent, divergent, and transform.

Egger, Anne

2003-03-18

285

Learning Assessment #1 - Plate Tectonics  

NSDL National Science Digital Library

In Part 1 of this activity, students are provided with a blank topographic profile and an associated tectonic plate boundary map. Students are asked to draw a schematic cross-section on the profile down to the asthenosphere including tectonic plates (with relative thicknesses of crust etc. appropriately illustrated), arrows indicating directions of plate movement, tectonic features (mid-ocean ridges, trenches and volcanic arcs) and symbols indicating where melting is occurring at depth. In Part 2, students are asked to provide geological and geophysical lines of evidence to support their placement of convergent and divergent boundaries, respectively. A bonus question asks students to predict what would happen if spreading along the Atlantic mid-ocean ridge were to stop. Students are referred to appropriate sections of the textbook to guide them in completing all the parts of this activity. Students are also provided with a checklist of required elements for both parts of the assignment.

Speta, Michelle; Reid, Leslie

286

Toward the Standard Population Synthesis Model of the X-Ray Background: Evolution of X-Ray Luminosity and Absorption Functions of Active Galactic Nuclei Including Compton-thick Populations  

NASA Astrophysics Data System (ADS)

We present the most up to date X-ray luminosity function (XLF) and absorption function of active galactic nuclei (AGNs) over the redshift range from 0 to 5, utilizing the largest, highly complete sample ever available obtained from surveys performed with Swift/BAT, MAXI, ASCA, XMM-Newton, Chandra, and ROSAT. The combined sample, including that of the Subaru/XMM-Newton Deep Survey, consists of 4039 detections in the soft (0.5-2 keV) and/or hard (>2 keV) band. We utilize a maximum likelihood method to reproduce the count rate versus redshift distribution for each survey, by taking into account the evolution of the absorbed fraction, the contribution from Compton-thick (CTK) AGNs, and broadband spectra of AGNs, including reflection components from tori based on the luminosity- and redshift-dependent unified scheme. We find that the shape of the XLF at z ~ 1-3 is significantly different from that in the local universe, for which the luminosity-dependent density evolution model gives much better description than the luminosity and density evolution model. These results establish the standard population synthesis model of the X-ray background (XRB), which well reproduces the source counts, the observed fractions of CTK AGNs, and the spectrum of the hard XRB. The number ratio of CTK AGNs to the absorbed Compton-thin (CTN) AGNs is constrained to be ?0.5-1.6 to produce the 20-50 keV XRB intensity within present uncertainties, by assuming that they follow the same evolution as CTN AGNs. The growth history of supermassive black holes is discussed based on the new AGN bolometric luminosity function.

Ueda, Yoshihiro; Akiyama, Masayuki; Hasinger, Günther; Miyaji, Takamitsu; Watson, Michael G.

2014-05-01

287

Voltage-current characteristics of a pin-plate system with different plate configurations  

NASA Astrophysics Data System (ADS)

In this paper, the voltage-current (V-I) characteristics of a pin-plate system with four types of collection plate configurations are studied experimentally. The collection plates consider a single metal plate, a metal plate with a fly ash cake layer, a metal plate with a clean filter media and a metal plate with a dirty filter media. The results show that the clean filter media has no obvious effect on the V-I characteristics. But the dirty filter media reduces the current density because of its high resistance. The thick fly ash cake layer increase current density because of the anti-corona effect but the increment is not very obvious.

Feng, Zhuangbo; Long, Zhengwei

2013-03-01

288

30 CFR 56.12032 - Inspection and cover plates.  

Code of Federal Regulations, 2013 CFR

...DEPARTMENT OF LABOR METAL AND NONMETAL MINE SAFETY AND HEALTH SAFETY AND HEALTH STANDARDS-SURFACE METAL AND NONMETAL MINES Electricity § 56.12032 Inspection and cover plates. Inspection and cover plates on electrical equipment and junction boxes...

2013-07-01

289

Modification of the contact area of a standard force platform and runway for small breed dogs.  

PubMed

Objectives: To develop a platform that used standard size force plates for large breed dogs to capture ground reaction force data from any size dog. Methods: A walkway platform was constructed to accommodate two force plates (60 cm x 40 cm) positioned in series to a variety of smaller sizes. It was constructed from a custom wood frame with thick aluminium sheet force plate covers that prevented transfer of load to the force plate, except for rectangular windows of three different dimensions. A friction study was performed to ensure plates did not translate relative to one another during gait trials. A prospective, observational, single crossover study design was used to compare the effect of force platform configuration (full plate size [original plate], half plate size [modified plate]) on ground reaction forces using eight adult healthy Labrador Retriever dogs. Results: Slippage of the steel plate on the force plate did not occur. Peak propulsion force was the only kinetic variable statistically different between the full size and half sized platforms. There were no clinically significant differences between the full and half force platforms for the variables and dogs studied. Discussion and conclusion: The modified force platform allows the original 60 x 40 cm force plate to be adjusted effectively to a 30 x 40 cm, 20 x 40 cm and 15 x 40 cm sized plate with no clinically significant change in kinetic variables. This modification that worked for large breed dogs will potentially allow kinetic analysis of a large variety of dogs with different stride lengths. PMID:24817147

Kapatkin, A S; Kim, J Y W; Garcia-Nolan, T C; Kim, S Y; Hayashi, K; Hitchens, P L; Stover, S M

2014-07-21

290

TFSSRA - THICK FREQUENCY SELECTIVE SURFACE WITH RECTANGULAR APERTURES  

NASA Technical Reports Server (NTRS)

Thick Frequency Selective Surface with Rectangular Apertures (TFSSRA) was developed to calculate the scattering parameters for a thick frequency selective surface with rectangular apertures on a skew grid at oblique angle of incidence. The method of moments is used to transform the integral equation into a matrix equation suitable for evaluation on a digital computer. TFSSRA predicts the reflection and transmission characteristics of a thick frequency selective surface for both TE and TM orthogonal linearly polarized plane waves. A model of a half-space infinite array is used in the analysis. A complete set of basis functions with unknown coefficients is developed for the waveguide region (waveguide modes) and for the free space region (Floquet modes) in order to represent the electromagnetic fields. To ensure the convergence of the solutions, the number of waveguide modes is adjustable. The method of moments is used to compute the unknown mode coefficients. Then, the scattering matrix of the half-space infinite array is calculated. Next, the reference plane of the scattering matrix is moved half a plate thickness in the negative z-direction, and a frequency selective surface of finite thickness is synthesized by positioning two plates of half-thickness back-to-back. The total scattering matrix is obtained by cascading the scattering matrices of the two half-space infinite arrays. TFSSRA is written in FORTRAN 77 with single precision. It has been successfully implemented on a Sun4 series computer running SunOS, an IBM PC compatible running MS-DOS, and a CRAY series computer running UNICOS, and should run on other systems with slight modifications. Double precision is recommended for running on a PC if many modes are used or if high accuracy is required. This package requires the LINPACK math library, which is included. TFSSRA requires 1Mb of RAM for execution. The standard distribution medium for this program is one 5.25 inch 360K MS-DOS format diskette. It is also available on a .25 inch streaming magnetic tape cartridge (Sun QIC-24) in UNIX tar format. This program was developed in 1992 and is a copyrighted work with all copyright vested in NASA.

Chen, J. C.

1994-01-01

291

Tectonic Plates and Plate Boundaries (WMS)  

NSDL National Science Digital Library

The earths crust is constantly in motion. Sections of the crust, called plates, push against each other due to forces from the molten interior of the earth. The areas where these plates collide often have increased volcanic and earthquake activity. These images show the locations of the plates and their boundaries in the earths crust. Convergent boundaries are areas where two plates are pushing against each other and one plate may be subducting under another. Divergent boundaries have two plates pulling away from each other and indicate regions where new land could be created. Transform boundaries are places where two plates are sliding against each other in opposite directions, and diffuse boundaries are places where two plates have the same relative motion. Numerous small microplates have been omitted from the plate image. These images have been derived from images made available by the United States Geological Surveys Earthquake Hazards Program.

Sokolowsky, Eric; Mitchell, Horace

2004-06-14

292

A preliminary study of bending stiffness alteration in shape changing nitinol plates for fracture fixation.  

PubMed

Nitinol is a promising biomaterial based on its remarkable shape changing capacity, biocompatibility, and resilient mechanical properties. Until now, very limited applications have been tested for the use of Nitinol plates for fracture fixation in orthopaedics. Newly designed fracture-fixation plates are tested by four-point bending to examine a change in equivalent bending stiffness before and after shape transformation. The goal of stiffness alterable bone plates is to optimize the healing process during osteosynthesis in situ that is customized in time of onset, percent change as well as being performed non-invasively for the patient. The equivalent bending stiffness in plates of varying thicknesses changed before and after shape transformation in the range of 24-73% (p values <0.05 for all tests). Tests on a Nitinol plate of 3.0 mm increased in stiffness from 0.81 to 0.98 Nm² (corresponding standard deviation 0.08 and 0.05) and shared a good correlation to results from numerical calculation. The stiffness of the tested fracture-fixation plates can be altered in a consistent matter that would be predicted by determining the change of the cross-sectional area moment of inertia. PMID:21286815

Olender, Gavin; Pfeifer, Ronny; Müller, Christian W; Gösling, Thomas; Barcikowski, Stephan; Hurschler, Christof

2011-05-01

293

Rozhen Observatory wide-field plate archives  

NASA Astrophysics Data System (ADS)

This paper provides an overview of the wide-field (>10) plate archives at disposal in the Institute of Astronomy and National Astronomical Observatory Rozhen of the Bulgarian Academy of Sciences. The plates with total number 10093 are obtained in the period November 1978 - February 1998 with the 2 m RCC telescope and 50/70/172 cm Schmidt telescope. The available plate catalogues are upgraded with new information, as well as with link to the digitized logbooks (in JPEG file format). The digitization with high quality EPSON flatbed scanners of the available 2 m RCC telescope plates (with low resolution in JPEG, and with high resolution in standardized FITS file format) is accomplished. The digitization of the available 50/70/172 cm Schmidt telescope plates is running. The low resolution images of the scanned Rozhen plates are included in the Wide-Field Plate Database (http://wfpdb.org) and accessible online.

Tsvetkova, K.; Tsvetkov, M.

2013-01-01

294

The Biggest Plates on Earth: Plate Tectonics  

NSDL National Science Digital Library

In this lesson, students investigate the movement of Earth's tectonic plates, the results of these movements, and how magnetic anomalies present at spreading centers document the motion of the crust. As a result of this activity, students will be able to describe the motion of tectonic plates, differentiate between three types of plate boundaries, infer what type of boundary exists between two tectonic plates, and understand how magnetic anomalies provide a record of geologic history and crustal motion around spreading centers. As an example, they will also describe plate boundaries and tectonic activity in the vicinity of the Juan de Fuca plate adjacent to the Pacific Northwest coast of North America.

295

Heterotrophic Plate Count Bacteria in Potable Water: Monitoring Methods and Applications.  

National Technical Information Service (NTIS)

The heterotrophic plate count (HPC), formerly known as the standard plate count, is a useful tool for enumerating bacteria in potable water. The document briefly reviews the development of the heterotrophic bacterial plate count for use in water quality m...

D. J. Reasoner

1989-01-01

296

EXTRAGALACTIC THICK DISKS  

Microsoft Academic Search

I briefly review the growing evidence that thick stellar disks surround most edgeon disk galaxies. Recent studies show that\\u000a these extragalactic thick disks have old ages, low metallicities, long scale lengths, and moderately flattened axial ratios,\\u000a much like the thick disk of the MilkyWay. However, the properties of thick disks change systematically with the mass of the\\u000a galaxy. The thick

Julianne J. Dalcanton; Anil C. Seth; Peter Yoachim

2007-01-01

297

Stop motion microphotography of laser driven plates  

SciTech Connect

Laser driven plates have been used for several years for high velocity shock wave and impact studies. Recent questions about the integrity and ablation rates of these plates coupled with an improved capability for microscopic stop motion photography led to this study. For these experiments, the plates were aluminum, coated on the ends of optical fibers. A high power laser pulse in the fiber ionizes the aluminum at the fiber/coating interface. The plasma thus created accelerates the remaining aluminum to high velocities, several kilometers per second. We defined {open_quotes}thick{close_quotes} or {open_quotes}thin{close_quotes} coatings as those where a flying plate (flyer) was launched vs. the material being completely ionized. Here we were specifically interested in the thick/thin boundary to develop data for the numerical models attempting to predict flyer behavior.

Frank, A.M. [Lawrence Livermore National Lab., CA (United States); Trott, W.M. [Sandia National Labs., Albuquerque, NM (United States)

1994-09-01

298

Earth's Decelerating Tectonic Plates  

Microsoft Academic Search

Space geodetic and oceanic magnetic anomaly constraints on tectonic plate motions are employed to determine a new global map of present-day rates of change of plate velocities. This map shows that Earth's largest plate, the Pacific, is presently decelerating along with several other plates in the Pacific and Indo-Atlantic hemispheres. These plate decelerations contribute to an overall, globally averaged slowdown

A M Forte; R Moucha; D B Rowley; S Quere; J X Mitrovica; N A Simmons; S P Grand

2008-01-01

299

A study of microclad thickness variation (1987)  

SciTech Connect

A study was conducted to investigate the thickness variation of microclad material used in fabricating 1E38 bridges. For the role sampled (nine reels), standard deviations within reels ranged from 6.11 to 12.07 {mu}in. Thickness variations within reels ranged from 16.2 to 40.9 {mu}in., with the average thickness between 142.90 and 161.28 {mu}in.

Ramachandran, R.S.; Armstrong, K.P.

1989-06-22

300

A theoretical analysis of FGM thin plates based on physical neutral surface  

Microsoft Academic Search

This paper presents a theoretical analysis to the FGM (functionally graded materials) thin plates based on the physical neutral surface. Under the assumption of changeable parameters such as the Young’s modulus E and the mass density ? along the thickness of the plate, the physical neutral surface of a FGM plate is determined by the theory of thin plate when

Da-Guang Zhang; You-He Zhou

2008-01-01

301

Computing relative plate velocities: a primer  

SciTech Connect

Standard models of present-day plate motions are framed in terms of rates and poles of rotation, in accordance with the well-known theorem due to Euler. This article shows how computation of relative plate velocities from such models can be viewed as a simple problem in spherical trigonometry. A FORTRAN subroutine is provided to perform the necessary computations.

Bevis, M.

1987-08-01

302

Plated-through hole testing. Final repot  

SciTech Connect

An improved microresistance testing method to measure the thickness of copper plating in plated-through holes of double-sided printed wiring boards is presented. A new probe design, combined with a microprocessor controller, makes it possible for a direct reading tester to provide variables data. Tester design and software programs for the system are included. Results of correlation studies, comparing the improved resistance method to cross-sectional measurements are presented. Limitations on the microresistance test method are discussed.

Abel, W.B.

1980-05-01

303

Plate Tectonics: Consequences of Plate Interactions  

NSDL National Science Digital Library

This Science Object is the fourth of five Science Objects in the Plate Tectonic SciPack. It identifies the events that may occur and landscapes that form as a result of different plate interactions. The areas along plate margins are active. Plates pushing against one another can cause earthquakes, volcanoes, mountain formation, and very deep ocean trenches. Plates pulling apart from one another can cause smaller earthquakes, magma rising to the surface, volcanoes, and oceanic valleys and mountains from sea-floor spreading. Plates sliding past one another can cause earthquakes and rock deformation. Learning Outcomes:� Explain why volcanoes and earthquakes occur along plate boundaries. � Explain how new sea floor is created and destroyed.� Describe features that may be seen on the surface as a result of plate interactions.

National Science Teachers Association (NSTA)

2006-11-01

304

Caribbean plate tectonics  

NSDL National Science Digital Library

This illustration available at Wikimedia Commons shows the plate tectonic setting in the Caribbean. Plate boundaries are color-coded by margin type and plate motions are noted with direction and magnitude in mm/yr.

Sting; Commons, Wikimedia

305

Frequencies of Piezoelectrically Forced Vibrations of Electroded, Doubly Rotated, Quartz Plates.  

National Technical Information Service (NTIS)

Two-dimensional equations of motion of piezoelectric crystal plates, obtained from the three-dimensional equations of linear piezoelectricity by expansion in power series of the thickness coordinate of the plate, are solved for forced vibrations of electr...

1983-01-01

306

Variations in lithospheric thickness on Venus  

NASA Technical Reports Server (NTRS)

Recent analyses of Magellan data have indicated many regions exhibiting topograhic flexure. On Venus, flexure is associated predominantly with coronae and the chasmata with Aphrodite Terra. Modeling of these flexural signatures allows the elastic and mechanical thickness of the lithosphere to be estimated. In areas where the lithosphere is flexed beyond its elastic limit the saturation moment provides information on the strength of the lithosphere. Modeling of 12 flexural features on Venus has indicated lithospheric thicknesses comparable with terrestrial values. This has important implications for the venusian heat budget. Flexure of a thin elastic plate due simultaneously to a line load on a continuous plate and a bending moment applied to the end of a broken plate is considered. The mean radius and regional topographic gradient are also included in the model. Features with a large radius of curvature were selected so that a two-dimensional approximation could be used. Comparisons with an axisymmetric model were made for some features to check the validity of the two-dimensional assumption. The best-fit elastic thickness was found for each profile crossing a given flexural feature. In addition, the surface stress and bending moment at the first zero crossing of each profile were also calculated. Flexural amplitudes and elastic thicknesses obtained for 12 features vary significantly. Three examples of the model fitting procedures are discussed.

Johnson, C. L.; Sandwell, David T.

1992-01-01

307

Heterotrophic plate count methodology in the United States  

Microsoft Academic Search

In the United States (US), the history of bacterial plate counting (BPC) methods used for water can be traced largely through Standard Methods for the Examination of Water and Wastewater (Standard Methods). The bacterial count method has evolved from the original Standard Methods (1st edition, 1905) plate count which used nutrient gelatin and incubation at 20 °C for 48 h,

Donald J Reasoner

2004-01-01

308

A THUMBNAIL HISTORY OF HETEROTROPHIC PLATE COUNT (HPC) METHODOLOGY IN THE UNITED STATES  

EPA Science Inventory

Over the past 100 years, the method of determining the number of bacteria in water, foods or other materials has been termed variously as: bacterial plate count, total plate count, total viable plate count, aerobic plate count, standard plate cound and more recently, heterotrophi...

309

Deformation and fracture of plates of finite thickness  

Microsoft Academic Search

Plane theories of elasticity are the theoretical foundation of many important developments in engineering. However, the understanding of the elastic solutions derived under plane stress or plane strain assumption, is rather far from complete. In particular, it is not clear how adequate the classical two-dimensional solutions of the plane theories of elasticity are when applied to the analysis of actual

A. Kotousov; S. Harding; J. Codrington

2009-01-01

310

Crack Under Shear Loading in a Plate of Finite Thickness  

Microsoft Academic Search

Application of the plane theory of elasticity to planar crack geometries leads to the concept of stress singularity and stress intensity factor, which are the cornerstone of contemporary fracture mechanics. However, the stress state near an actual crack tip is always three-dimensional, and the meaning of the results obtained with the plane theory of elasticity and their relation to the

A. Kotousov; J. Codrington

2007-01-01

311

Steady-state heat conduction in multilayered composite plates and shells  

NASA Technical Reports Server (NTRS)

A study is made of a predictor-corrector procedure for the accurate determination of the temperature and heat flux distributions in thick multilayered composite plates and shells. A linear through-the-thickness temperature distribution is used in the predictor phase. The functional dependence of temperature on the thickness coordinate is then calculated a posteriori and used in the corrector phase. Extensive numerical results are presented for linear steady-state heat conduction problems, showing the effects of variation in the geometric and lamination parameters on the accuracy of the thermal response predictions of the predictor-corrector approach. Both antisymmetrically laminated anisotropic plates and multilayered orthotropic cylinders are considered. The solutions are assumed to be periodic in the surface coordinates. For each problem the standard of comparison is taken to be the analytic three-dimensional solution based on treating each layer as a homogeneous anisotropic medium. The potential of the predictor-corrector approach for predicting the thermal response of multilayered plates and shells with complicated geometry is discussed.

Noor, A. K.; Burton, W. S.

1991-01-01

312

Plate Tectonics: Diverging, Converging, and Transform Boundaries  

NSDL National Science Digital Library

In this lesson, students will learn to distinguish the different layers of the Earth, observe the effects of plate movements, and explore the reasons for earthquakes and volcanoes. They will label and measure the thicknesses of each layer of the Earth (lithosphere, asthenosphere, etc.) and record their results, construct models from sand and clay to illustrate what happens at the three types of plate boundaries (transform, diverging, and converging), and investigate convergent plate boundaries to see which scenarios may create earthquakes and/or volcanoes.

313

High order shear horizontal modes for minimum remnant thickness.  

PubMed

Thickness mapping in aging structures suffering from corrosion is challenging especially when the structure is only partially accessible. In plates the high order shear horizontal guided wave modes all have a cutoff frequency thickness product below which they cannot propagate. This property is potentially attractive to estimate the minimum remnant thickness between two transducers. When using a source and a sensor array it is possible to control the number of modes being excited and the size of the region interrogated by the technique. Finite element simulations were used to show that by exciting multiple guided wave modes simultaneously and identifying which modes are received by a sensor array it is possible to estimate the minimum remaining thickness along the propagation path. Initial experimental results showed excellent agreement with the finite element simulations when the plate is uniform and with a thickness reduction between the source and the sensor arrays the minimum remnant thickness was underestimated by approximately 20%. PMID:24472432

Belanger, Pierre

2014-04-01

314

Temperature-dependent creep buckling of plates  

NASA Technical Reports Server (NTRS)

Time-dependent lateral deflection of flat rectangular plates is predicted by the Norton-Bailey (Norton 1929, Bailey 1935) power law for material creep. The plates have a through-thickness steady-state temperature distribution, and the effects are considered by using Maxwell's law to modify the power creep law. Equations are derived for creep exponents of 3 and 5, using the sandwich plate element to predict creep buckling of plates. Predictions of creep buckling with a temperature variation between the inner and outer plate surfaces are found to be somewhat dependent on the creep buckling relationship assumed. When significant scatter justifies a variation in the creep constants up to an order of magnitude, discrepancies in predictions using the two exponents are reasonable, and for one engineering material, the predictions have the same degree of agreement with experimental data as have the respective creep laws.

Ross, D. A.; Berke, L.

1981-01-01

315

Bipolar plates for PEM fuel cells  

NASA Astrophysics Data System (ADS)

The bipolar plates are in weight and volume the major part of the PEM fuel cell stack, and are also a significant contributor to the stack costs. The bipolar plate is therefore a key component if power density has to increase and costs must come down. Three cell plate technologies are expected to reach targeted cost price levels, all having specific advantages and drawbacks. NedStack has developed a conductive composite materials and a production process for fuel cell plates (bipolar and mono-polar). The material has a high electric and thermal conductivity, and can be processed into bipolar plates by a proprietary molding process. Process cycle time has been reduced to less than 10 s, making the material and process suitable for economical mass production. Other development work to increase material efficiency resulted in thin bipolar plates with integrated cooling channels, and integrated seals, and in two-component bipolar plates. Total thickness of the bipolar plates is now less than 3 mm, and will be reduced to 2 mm in the near future. With these thin integrated plates it is possible to increase power density up to 2 kW/l and 2 kW/kg, while at the same time reducing cost by integrating other functions and less material use.

Middelman, E.; Kout, W.; Vogelaar, B.; Lenssen, J.; de Waal, E.

316

Accuracy of the TRIA3 thick shell element  

NASA Technical Reports Server (NTRS)

The accuracy of the new TRIA3 thick shell element is assessed via comparison with a theoretical solution for thick homogeneous and honeycomb flat simply supported plates under the action of a uniform pressure load. The theoretical thick plate solution is based on the theory developed by Reissner and includes the effects of transverse shear flexibility which are not included in the thin plate solutions based on Kirchoff plate theory. In addition, the TRIA3 is assessed using a set of finite element test problems developed by the MacNeal-Schwendler Corp. (MSC). Comparison of the COSMIC TRIA3 element as well as those from MSC and Universal Analytics Inc. (UAI) for these problems is presented. The current COSMIC TRIA3 element is shown to have excellent comparison with both the theoretical solutions and also those from the two commercial versions of NASTRAN with which it is compared.

Case, William R.; Concha, Marco; Mcginnis, Mark

1992-01-01

317

Accuracy of the QUAD4 thick shell element  

NASA Technical Reports Server (NTRS)

The accuracy of the relatively new QUAD4 thick shell element is assessed via comparison with a theoretical solution for thick homogeneous and honeycomb flat simply supported plates under the action of a uniform pressure load. The theoretical thick plate solution is based on the theory developed by Reissner and includes the effects of transverse shear flexibility which are not included in the thin plate solutions based on Kirchoff plate theory. In addition, the QUAD4 is assessed using a set of finite element test problems developed by the MacNeal-Schwendler Corp. (MSC). Comparison of the COSMIC QUAD4 element as well as those from MSC and Universal Analytics, Inc. (UAI) for these test problems is presented. The current COSMIC QUAD4 element is shown to have excellent comparison with both the theoretical solutions and also those from the two commercial versions of NASTRAN that it was compared to.

Case, William R.; Bowles, Tiffany D.; Croft, Alicia K.; Mcginnis, Mark A.

1990-01-01

318

Adhesion Between Rubber Compound and Copper-Film-Plated Steel Cord  

Microsoft Academic Search

Four copper-film-plated steel cords (abbreviated hereafter as copper-plated cord) with different thickness of copper film from 32 to 90 nm were prepared and their adhesion properties with rubber compound were investigated. Adhesion properties improved with the decrease in the thickness of the copper film. Unaged pull-out force and rubber coverage of copper-plated cords were inferior to those of brass-plated cord,

Pyong Lae Cho; Gyung Soo Jeon; Seung Kyun Ryu; Gon Seo

1999-01-01

319

High-performance multilevel blazed x-ray microscopy Fresnel zone plates: Fabricated using x-ray lithography  

SciTech Connect

Diffractive lenses are becoming the optical elements of choice for many applications. One type of diffractive lens, the binary zone plate, has already demonstrated high-resolution performance experimentally. However, in order to increase the diffraction efficiency of these zone plates, a blazed grating profile must be used. This can best be approximated by a staircase grating profile, created by multilevel exposures. Using x-ray lithograph, we fabricated for the first time circular, linear bi- and trilevel zone plates, with gold structures 0.75 [mu]m thick (per level), on silicon nitride substrates. The zone plates were designed for use at a wavelength of 1.54 A, and had a theoretical efficiency of 68.5% for bilevel and 81.5% for trilevel zone plates. Due to the large depth of focus and high resolution inherent to x-ray lithography, the finished zone plate exhibits very steep sidewall profiles, with linewidth resolution down to 0.25 [mu]m. Such vertical sidewalls are essential for achieving high lens efficiency. Fabrication errors, such as thickness variation in the electroplated gold and misalignment, were considered, and their effect on the optical efficiency of the zone plate was estimated. Alignment errors between levels were minimized, achieving a best result of 25 nm (3[sigma]). In fabricating the zone plates, we employed standard integrated device tools, such as a Leica Cambridge Electron Beam microfabricator (EBMF) 10cs/120 electron-beam writer for the x-ray mask fabrication, and a Suss 200 x-ray stepper for the multilevel exposures. Thus, we have shown that it will be possible to fabricate many lenses, with a variety of optical characteristics, in one wafer.

Di Fabrizio, E.; Gentili, M.; Grella, L.; Baciocchi, M. (Istituto di Elettronica dello Stato Solido, Consiglio Nazionale delle Ricerche (CNR), I-00156 Rome (Italy)); Krasnoperova, A.; Cerrina, F. (Department of Electrical and Computer Engineering, Center for X-ray Lithography, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States)); Yun, W.; Lai, B.; Gluskin, E. (Argonne National Laboratory, Argonne, Illinois 60439 (United States))

1994-11-01

320

Volcano spacing and plate rigidity  

SciTech Connect

In-plane stresses, which accompany the flexural deformation of the lithosphere under the load adjacent volcanoes, may govern the spacing of volcanoes in hotspot provinces. Specifically, compressive stresses in the vicinity of a volcano prevent new upwelling in this area, forcing a new volcano to develop at a minimum distance that is equal to the distance in which the radial stresses change from compressional to tensile (the inflection point). If a volcano is modeled as a point load on a thin elastic plate, then the distance to the inflection point is proportional to the thickness of the plate to the power of 3/4. Compilation of volcano spacing in seven volcanic groups in East Africa and seven volcanic groups of oceanic hotspots shows significant correlation with the elastic thickness of the plate and matches the calculated distance to the inflection point. In contrast, volcano spacing in island arcs and over subduction zones is fairly uniform and is much larger than predicted by the distance to the inflection point, reflecting differences in the geometry of the source and the upwelling areas.

Brink, U. (Stanford Univ., California (USA))

1991-04-01

321

MTR plates modeling with MAIA  

SciTech Connect

MAIA is a thermo-mechanical code dedicated to the modeling of MTR fuel plates. The main physical phenomena modeled in the code are the cladding oxidation, the interaction between fuel and Al-matrix, the swelling due to fission products and the Al/fuel particles interaction. The creeping of the plate can be modeled in the mechanical calculation. MAIA has been validated on U-Mo dispersion fuel experiments such as IRIS 1 and 2 and FUTURE. The results are in rather good agreement with post-irradiation examinations. MAIA can also be used to calculate in-pile behavior of U{sub 3}Si{sub 2} plates as in the SHARE experiment irradiated in the SCK/Mol BR2 reactor. The main outputs given by MAIA throughout the irradiation are temperatures, cladding oxidation thickness, interaction thickness, volume fraction of meat constituents, swelling, displacements, strains and stresses. MAIA is originally a two-dimensional code but a three-dimensional version is currently under development. (author)

Marelle, V.; Dubois, S.; Ripert, M.; Noirot, J. [DEN/DEC, CEA Cadarache, 13108 St Paul Lez Durance (France); Lemoine, P. [DEN/DSOE, CEA Saclay, 91191 Gif sur Yvette (France)

2008-07-15

322

Wave propagation and transient response of a FGM plate under a point impact load based on higher-order shear deformation theory  

Microsoft Academic Search

In this paper, the wave propagation and transient response of an infinite functionally graded plate under a point impact load are presented. The effective material properties of functionally graded materials (FGMs) for the plate are assumed to vary continuously through the plate thickness and be distributed according to a volume fraction power law along the plate thickness. Based on the

Dan Sun; Song-Nan Luo

2011-01-01

323

Rotation angle measurement based on white-light interferometry with a standard optical flat.  

PubMed

We propose a simple white-light interferometric method of measuring a one-dimensional rotation angle with use of an optical plane parallel plate of standard refractive index. The phase change of the interference pattern of the interferometer during the rotation of the flat plate of known refractive index and thickness placed in one of the interferometer's arms is used for determination of the rotation angle. This method has been demonstrated for an accurate angle measurement over the angle range from 0° to 40° within a maximum uncertainty of 0.057°. PMID:22358161

Yun, Hyo Geun; Kim, Seung Hwan; Jeong, Heung Sun; Kim, Kyong Hon

2012-02-20

324

Sputtering and ion plating  

NASA Technical Reports Server (NTRS)

The proceedings of a conference on sputtering and ion plating are presented. Subjects discussed are: (1) concepts and applications of ion plating, (2) sputtering for deposition of solid film lubricants, (3) commercial ion plating equipment, (4) industrial potential for ion plating and sputtering, and (5) fundamentals of RF and DC sputtering.

1972-01-01

325

Plate Tectonics Animation  

NSDL National Science Digital Library

Plate tectonics describes the behavior of Earth's outer shell, with pieces (plates) bumping and grinding and jostling each other about. Explore these maps and animations to get a jump start on understanding plate tectonic processes, history, and how motion of the plates affects our planet today.

2002-01-01

326

Realization of a broadband low-frequency plate silencer using sandwich plates  

NASA Astrophysics Data System (ADS)

A broadband low-frequency plate silencer is realized experimentally using sandwich plates. The silencer consists of an expansion chamber with two side-branch cavities, each covered by a light but extremely stiff plate. The requirement for high bending stiffness and low density of the plate is satisfied with a sandwich construction by adhering two high-rigidity thin sheets with a relatively thick and light foam core. A test rig is built with a square duct of 100 mm in dimension, and each cavity is 100 mm deep and 500 mm long. Three types of sandwich plates with different mechanical properties are tested. The plate having the highest bending stiffness and lowest density results in a measured stopband from 133 to 274 Hz in which the transmission loss is higher than 10 dB over the whole frequency band. Comparisons between the three sandwich plates partly confirm the theoretical findings on the effect of plate properties on the silencer performance. It is also shown that the mathematical model based on homogeneous plates can provide satisfactory prediction on the performance of a sandwich plate silencer in the low-frequency range of interest. Experimental and theoretical results are found to be in fair agreement.

Wang, Chunqi; Cheng, Li; Huang, Lixi

2008-12-01

327

Mapping Plate Tectonic Boundaries  

NSDL National Science Digital Library

To prepare for this activity, students do background reading on Plate Tectonics from the course textbook. Students also participate in a lecture on the discovery and formulation of the unifying theory of plate tectonics, and the relationship between plate boundaries and geologic features such as volcanoes. Lastly, in lecture, students are introduced to a series of geologic hazards caused by certain plate tectonic interactions. The activity gives students practices at identifying plate boundaries and allows them to explore lesser known tectonically active regions.

Kerwin, Michael

328

Mechanics of Projectile Impact against Thin Plates.  

National Technical Information Service (NTIS)

A comprehensive theoretical and experimental investigation was undertaken to study the effects of projectile impact on plates involving targets of soft aluminum and mild steel, with thicknesses ranging from 0.05 to 1 in. The preponderance of the tests and...

W. Goldsmith

1984-01-01

329

Prisms and Plates for Showing Dichromatism  

Microsoft Academic Search

DICHROMATISM, or the change of colour of an absorbing medium with increasing thickness, is usually shown with plates of coloured glass. It is not always easy to obtain the right kind of glass, and only a few of the aniline dyes are suitable for the purpose. The medium should transmit two distinct regions of the spectrum, the absorption coefficient for

R. W. Wood

1902-01-01

330

Thermal postbuckling analysis of FGM skew plates  

Microsoft Academic Search

In this paper, the postbuckling behavior of functionally graded material (FGM) skew plates under thermal load is investigated based on the shear deformable finite element approach. The material is graded in the thickness direction according to a power-law distribution in terms of the volume fractions of the constituents. The Mori–Tanaka homogenization method is used to estimate the effective material properties

T. Prakash; M. K. Singha; M. Ganapathi

2008-01-01

331

Applicability of thermal conduction models to mid-plate volcanism: Comments on a paper by Gass et al  

Microsoft Academic Search

The proposition that mid-plate ('hot spot') magmatism is strongly discouraged by a combination of thick lithosphere and rapid plate motion is examined empirically on a global basis and found to be inadequate. Although hot spots perhaps tend to 'avoid' cratonic areas, the nonrandom worldwide distribution of hot spots appears primarily to reflect the state of the sublithospheric mantle. Plate thickness

P. R. Vogt

1981-01-01

332

Thermal distortion tests of aluminum and stainless steel plates  

SciTech Connect

An important upgrade to the STAR detector at the Brookhaven National Laboratory RHIC accelerator will be an electromagnetic calorimeter. One design being considered for this calorimeter involves cast lead modules covering {Delta}{phi} = 6{degree} and 0 {le} {vert_bar}{eta}{vert_bar} {le} 1. These modules would consist of alternating layers of lead and sheets of plastic scintillator. The gaps for scintillator between the layers of lead would be created by parallel aluminum plates of thickness {approx_equal}6.6 mm = 0.260in. in the mold for the modules. These plates would need to be machined or ground to be reasonably flat, perhaps to {plus_minus}0.003in., and of uniform thickness from plate to plate. These requirements are imposed by the need to remove the plates from the casting after cooling, and to have good uniformity of the lead layer thickness, which gives good performance for the modules as a calorimeter. Aluminum was chosen for the plates because of its high coefficient of thermal expansion. An important cost in this calorimeter design is associated with the machining or grinding of the plates to proper thickness and flatness. In most cost estimates, it has been assumed that the mold parts could be used many times. This note describes a simple test which was conducted to investigate possible distortions in the plates after repeated heating to temperatures at which the lead would be poured into the mold and cooling.

Bielick, E.; Fornek, T.; Spinka, H.; Underwood, D.

1993-06-25

333

Extension of generalized plane strain plates with reinforced cracks  

Microsoft Academic Search

Applying the transversally isotropic generalized plane strain plate of Mindlin and Kane, as refined by Kotousov and Wang, the authors use Fourier transforms to develop a hyper-singular line-spring model for a reinforced crack under extensional loads, enabling the analysis of cracks in plates of arbitrary thickness. The new model is used to develop fracture mechanics geometry correction factors to account

R. J. Clark; D. P. Romilly

2008-01-01

334

A PROBLEM OF WIAGNETOSTATI CS RELATED TO THIN PLATES (*)  

Microsoft Academic Search

Motivated by an industrial project concerning the electrolysis cells f or the production of aluminium, we study the asymptotic behaviour of fer romagnetic plates first when the magnetic susceptibility is large and then when the thickness of the plates is small €> Elsevier, Paris

Jean DESCLOUX; Michel FLUECK; Michel V. ROMERIOC

335

ASYMPTOTIC THERMOELASTIC ANALYSIS OF ANISOTROPIC INHOMOGENEOUS AND LAMINATED PLATES  

Microsoft Academic Search

On the basis of three-dimensional elasticity without a priori assumptions, we develop an asymptotic theory for the thermoelastic analysis of anisotropic inhomogeneous plates subject to general temperature variations and under the action of lateral loads. The inhomogeneities considered are in the thickness direction, and the laminated plate represents an important special case. Through reformulation of the basic equations and nondimensionalization

Jiann-Quo Tarn; Yung-Ming Wang

1995-01-01

336

Bending response of inhomogeneous fiber-reinforced viscoelastic sandwich plates  

Microsoft Academic Search

The static response of an inhomogeneous fiber-reinforced viscoelastic sandwich plate is investigated by using the first-order\\u000a shear deformation theory. Several types of sandwich plates are considered taking into account the symmetry of the plate and\\u000a the thickness of each layer. In addition, two cases are considered depending on the viscoelastic material which are included\\u000a in the core or the faces

M. N. M. Allam; A. M. Zenkour; H. F. El-Mekawy

2010-01-01

337

Postbuckling of stiffened composite plates under combined loading  

NASA Technical Reports Server (NTRS)

An analysis methodology for the postbuckling behavior of laminated plates under combined in-plane normal and shear loading is presented. The plates are simply supported on their ends and elastically restrained against rotation along their longitudinal edges. Discrete thickness changes along the plate edges are included in the formulation to account for attached stiffener flanges and/or edge pad-ups. The resulting analytical approach is suitable for inclusion in a preliminary sizing procedure for longitudinally stiffened composite panels.

Kunz, Richard K.

1990-01-01

338

CMUT Fabrication Based On A Thick Buried Oxide Layer  

PubMed Central

We introduce a versatile fabrication process for direct wafer-bonded CMUTs. The objective is a flexible fabrication platform for single element transducers, 1D and 2D arrays, and reconfigurable arrays. The main process features are: A low number of litho masks (five for a fully populated 2D array); a simple fabrication sequence on standard MEMS tools without complicated wafer handling (carrier wafers); an improved device reliability; a wide design space in terms of operation frequency and geometric parameters (cell diameter, gap height, effective insulation layer thickness); and a continuous front face of the transducer (CMUT plate) that is connected to ground (shielding for good SNR and human safety in medical applications). All of this is achieved by connecting the hot electrodes individually through a thick buried oxide layer, i.e. from the handle layer of an SOI substrate to silicon electrodes located in each CMUT cell built in the device layer. Vertical insulation trenches are used to isolate these silicon electrodes from the rest of the substrate. Thus, the high electric field is only present where required – in the evacuated gap region of the device and not in the insulation layer of the post region. Array elements (1D and 2D) are simply defined be etching insulation trenches into the handle wafer of the SOI substrate.

Kupnik, Mario; Vaithilingam, Srikant; Torashima, Kazutoshi; Wygant, Ira O.; Khuri-Yakub, Butrus T.

2010-01-01

339

An exact solution for buckling of functionally graded circular plates based on higher order shear deformation plate theory under uniform radial compression  

Microsoft Academic Search

In this research, mechanical buckling of circular plates composed of functionally graded materials (FGMs) is considered. Equilibrium and stability equations of a FGM circular plate under uniform radial compression are derived, based on the higher order shear deformation plate theory (HSDT). Assuming that the material properties vary as a power form of the thickness coordinate variable z and using the

M. M. Najafizadeh; H. R. Heydari

2008-01-01

340

Plane wave quantity and its measurement of plate working surface  

NASA Astrophysics Data System (ADS)

This paper deals with the assay requirements and the method of plane. Wave quantity of the plate working surface according to the National Standards of 'cast iron plate' and 'rock plate', derives in detail, the detecting principle of plane wave detector and gives out the relationship between the partial plane error and the partial defect of the plate and the plane wave quantity. It also inquires into the relationship between the contact spot and 200 mm straight line wave and plane wave quantity.

Liu, Jun-Qi; Liu, Ya-Nan; Cao, Linxiang; Zhao, XiaoMing

1999-11-01

341

Three-dimensional dynamic models of subducting plate-overriding plate-upper mantle interaction  

NASA Astrophysics Data System (ADS)

We present fully dynamic generic three-dimensional laboratory models of progressive subduction with an overriding plate and a weak subduction zone interface. Overriding plate thickness (TOP) is varied systematically (in the range 0-2.5 cm scaling to 0-125 km) to investigate its effect on subduction kinematics and overriding plate deformation. The general pattern of subduction is the same for all models with slab draping on the 670 km discontinuity, comparable slab dip angles, trench retreat, trenchward subducting plate motion, and a concave trench curvature. The narrow slab models only show overriding plate extension. Subduction partitioning (vSP? / (vSP? + vT?)) increases with increasing TOP, where trenchward subducting plate motion (vSP?) increases at the expense of trench retreat (vT?). This results from an increase in trench suction force with increasing TOP, which retards trench retreat. An increase in TOP also corresponds to a decrease in overriding plate extension and curvature because a thicker overriding plate provides more resistance to deform. Overriding plate extension is maximum at a scaled distance of ~200-400 km from the trench, not at the trench, suggesting that basal shear tractions resulting from mantle flow below the overriding plate primarily drive extension rather than deviatoric tensional normal stresses at the subduction zone interface. The force that drives overriding plate extension is 5%-11% of the slab negative buoyancy force. The models show a positive correlation between vT? and overriding plate extension rate, in agreement with observations. The results suggest that slab rollback and associated toroidal mantle flow drive overriding plate extension and backarc basin formation.

Meyer, C.; Schellart, W. P.

2013-02-01

342

Local plate/rod descriptors of 3D trabecular bone micro-CT images from medial axis topologic analysis  

SciTech Connect

Purpose: Trabecular bone microarchitecture is made of a complex network of plate and rod structures evolving with age and disease. The purpose of this article is to propose a new 3D local analysis method for the quantitative assessment of parameters related to the geometry of trabecular bone microarchitecture. Methods: The method is based on the topologic classification of the medial axis of the 3D image into branches, rods, and plates. Thanks to the reversibility of the medial axis, the classification is next extended to the whole 3D image. Finally, the percentages of rods and plates as well as their mean thicknesses are calculated. The method was applied both to simulated test images and 3D micro-CT images of human trabecular bone. Results: The classification of simulated phantoms made of plates and rods shows that the maximum error in the quantitative percentages of plate and rods is less than 6% and smaller than with the structure model index (SMI). Micro-CT images of human femoral bone taken in osteoporosis and early or advanced osteoarthritis were analyzed. Despite the large physiological variability, the present method avoids the underestimation of rods observed with other local methods. The relative percentages of rods and plates were not significantly different between osteoarthritis and osteoporotic groups, whereas their absolute percentages were in relation to an increase of rod and plate thicknesses in advanced osteoarthritis with also higher relative and absolute number of nodes. Conclusions: The proposed method is model-independent, robust to surface irregularities, and enables geometrical characterization of not only skeletal structures but entire 3D images. Its application provided more accurate results than the standard SMI on simple simulated phantoms, but the discrepancy observed on the advanced osteoarthritis group raises questions that will require further investigations. The systematic use of such a local method in the characterization of trabecular bone samples could provide new insight in bone microarchitecture changes related to bone diseases or to those induced by drugs or therapy.

Peyrin, Francoise; Attali, Dominique; Chappard, Christine; Benhamou, Claude Laurent [CREATIS, UMR CNRS 5220, 69621 Villeurbanne (France); Inserm, U 630, 69621 Villeurbanne (France); Insa de Lyon, 69621 Villeurbanne (France); Universite Lyon I, 69621 Villeurbanne (France); Universite de Lyon, 69621 Villeurbanne (France) and ESRF (European Synchrotron Radiation Facility), BP 220, 38043 Grenoble (France); GIPSA Laboratory, UMR CNRS 5216, 38402 Grenoble (France); Inserm, U 658, 45032 Orleans Cedex 1 (France) and B20A, UMR7052 CNRS, Universite Paris 7, 75010 Paris (France); Inserm, U 658, 45032 Orleans Cedex 1 (France)

2010-08-15

343

Thick film hydrogen sensor  

DOEpatents

A thick film hydrogen sensor element includes an essentially inert, electrically-insulating substrate having deposited thereon a thick film metallization forming at least two resistors. The metallization is a sintered composition of Pd and a sinterable binder such as glass frit. An essentially inert, electrically insulating, hydrogen impermeable passivation layer covers at least one of the resistors.

Hoffheins, Barbara S. (Knoxville, TN); Lauf, Robert J. (Oak Ridge, TN)

1995-01-01

344

Education and "Thick" Epistemology  

ERIC Educational Resources Information Center

In this essay Ben Kotzee addresses the implications of Bernard Williams's distinction between "thick" and "thin" concepts in ethics for epistemology and for education. Kotzee holds that, as in the case of ethics, one may distinguish between "thick" and "thin" concepts of epistemology and, further, that this distinction points to the importance of…

Kotzee, Ben

2011-01-01

345

Thick film hydrogen sensor  

DOEpatents

A thick film hydrogen sensor element includes an essentially inert, electrically-insulating substrate having deposited thereon a thick film metallization forming at least two resistors. The metallization is a sintered composition of Pd and a sinterable binder such as glass frit. An essentially inert, electrically insulating, hydrogen impermeable passivation layer covers at least one of the resistors. 8 figs.

Hoffheins, B.S.; Lauf, R.J.

1995-09-19

346

Piezoactuation of sandwich plates with viscoelastic cores  

NASA Astrophysics Data System (ADS)

Experimental and analytical validations of a Galerkin analysis of sandwich plates is presented in this paper. The 3-layered sandwich plate specimen consists of isotropic face-plates with surface bonded piezo-electric patch actuators, and a viscoelastic core. The experimental validation is conducted by testing sandwiched plates that are 67.31 cm (26.5') long, 52.07 cm (20.5') wide and nominally 0.16 cm (1/16') thick. The analysis includes the membrane and transverse energies in the face plates, and shear energies in the core. The shear modulus of the dissipative core is assumed to be complex and variant with frequency and temperature. The Golla-Hughes-McTavish (GHM) method is used to account for the frequency dependent properties of the viscoelastic core. Experiments have been conducted on sandwich plates with aluminum face-plates under clamped boundary conditions to validate the model for isotropic face-plates. Symmetric and asymmetric sandwiches have been tested. The maximum error in damped natural frequency predictions obtained via the assumed modes solutions is less than 11%. Analytical studies on the influence of the number of assumed modes in the Galerkin approximation, and the temperature variation, have been conducted. Error in the first plate bending mode is 112% when only a single in-plane mode is used; error reduces to 3.95% as the number of in-plane modes is increased to 25 in each of the in-plane directions. The study on the temperature influence shows that every plate mode has a corresponding temperature, wherein the loss factor is maximized.

Wang, Gang; Wereley, Norman M.

1999-06-01

347

My Plate Food Guide  

MedlinePLUS

... you won't get the best nutrition. 1. Vegetables The vegetable portion of MyPlate is shown in green. It's ... the largest sections on the plate. That's because vegetables provide many of the vitamins and minerals we ...

348

Plate Tectonics: Further Evidence  

NSDL National Science Digital Library

The representation depicts the spreading of the sea floor along the mid-ocean ridges. The resource generally describes the theory of plate tectonics, including the movement of plates with regard to one another.

349

External Resource: Plate Tectonics  

NSDL National Science Digital Library

This Windows to the Universe interactive webpage connects students to the study and understanding of plate tectonics, the main force that shapes our planets surface. Topics: plate tectonics, lithosphere, subduction zones, faults, ridges.

1900-01-01

350

Earth's Decelerating Tectonic Plates  

SciTech Connect

Space geodetic and oceanic magnetic anomaly constraints on tectonic plate motions are employed to determine a new global map of present-day rates of change of plate velocities. This map shows that Earth's largest plate, the Pacific, is presently decelerating along with several other plates in the Pacific and Indo-Atlantic hemispheres. These plate decelerations contribute to an overall, globally averaged slowdown in tectonic plate speeds. The map of plate decelerations provides new and unique constraints on the dynamics of time-dependent convection in Earth's mantle. We employ a recently developed convection model constrained by seismic, geodynamic and mineral physics data to show that time-dependent changes in mantle buoyancy forces can explain the deceleration of the major plates in the Pacific and Indo-Atlantic hemispheres.

Forte, A M; Moucha, R; Rowley, D B; Quere, S; Mitrovica, J X; Simmons, N A; Grand, S P

2008-08-22

351

The PLATES Project  

NSDL National Science Digital Library

This is the web page for PLATES, a program of research into plate tectonic and geologic reconstructions at the University of Texas at Austin Institute for Geophysics. The page contains links to a brief overview of plate tectonics and plate reconstructions using the PLATES Project's global plate reconstruction model, in addition to movies in the format of powerpoint animations which can be downloaded for later use. Models are shown on the evolution of the earth's oceans and the movement of the earth's tectonic plates from the Late Precambrian through the present day, reconstructing (i.e. "predicting") geological environments through geologic history. Maps of the following can be accessed: late Neo-Proterozoic, Silurian, early Jurassic, early Cretaceous, Cretaceous-Tertiary Boundary, and Oligocene. Movies are available on the following subjects: global plate motion, Jurassic to present day, opening of the Indian Ocean, and tectonic evolution of the Arctic region.

352

Oxidation of the copper alloy with pure copper plating  

Microsoft Academic Search

The oxidation failure of a copper alloy lead frame with\\/without a copper plating layer was investigated. The oxidation rate and adhesion strength of oxide films on copper alloy substrates were studied by measuring the thickness and by carrying out peel tests. The adhesion strength of the oxide film was mainly influenced by the composition but not the thickness of the

Yuchen Liu; Jin Hu; Anmin Hu; Ming Li; Dali Mao

2012-01-01

353

Global Plate Driving Forces at 50Ma  

NASA Astrophysics Data System (ADS)

We apply a novel workflow utilising the BEM-Earth geodynamic software to analyse the global coupled plate-mantle dynamics at 50 Ma. A subduction history model based on kinematic data going as far back as 80 Ma was developed using the GPlates software. Advection of the plates into the mantle takes into account the absolute plate motions and lithospheric thickness derived from its age to produce an estimated density heterogeneity initial model condition in the upper mantle. The resulting global model consists of regions of a mantle viscosity and density structure that is post-processed to ensure smooth non-overlapping 3D surfaces. BEM-Earth is then free to evolve the model toward the 50 Ma solution. The evolution of the model is driven by self-consistent buoyancy driven mantle dynamics. We use the model velocity output to quantify changes in forces driving the plates before and after 50 Ma. We analyse the rapid change in plate motion of India, Africa and plates in the Pacific Ocean basin by considering slab-pull, ridge-push and mantle drag/suction forces that naturally result from such top-down driven mantle flow. We compare the results with plate kinematic reconstructions and other geological observations.

Butterworth, N. P.; Quevedo, L. E.; Müller, R. D.

2011-12-01

354

Scaling of energy absorbing composite plates  

NASA Astrophysics Data System (ADS)

The energy absorption response and crushing characteristics of geometrically scaled graphite-Kevlar epoxy composite plates were investigated. Three different trigger mechanisms including chamfer, notch, and steeple geometries were incorporated into the plate specimens to initiate crushing. Sustained crushing was achieved with a simple test fixture which provided lateral support to prevent global buckling. Values of specific sustained crushing stress (SSCS) were obtained which were comparable to values reported for tube specimens from previously published data. Two sizes of hybrid plates were fabricated; a baseline or model plate, and a full-scale plate with in-plane dimensions scaled by a factor of two. The thickness dimension of the full-scale plates was increased using two different techniques; the ply-level method in which each ply orientation in the baseline laminate stacking sequence is doubled, and the sublaminate technique in which the baseline laminate stacking sequence is repeated as a group. Results indicated that the SSCS is independent of trigger mechanism geometry. However, a reduction in the SSCS of 10-25 percent was observed for the full-scale plates as compared with the baseline specimens, indicating a scaling effect in the crushing response.

Jackson, Karen; Morton, John; Traffanstedt, Catherine; Boitnott, Richard

355

Redesign of plates by large admissible perturbations  

NASA Astrophysics Data System (ADS)

The problem of structural redesign of plates for static deflection and modal dynamics objectives is formulated and solved by the method of large admissible perturbations. The perturbation approach to redesign is first used to develop response equations for the objective plate design based on its specifications and the baseline plate design. The equations of the objective state are strongly nonlinear implicit expressions of the variable plate thickness. A large admissible perturbations algorithm is developed to solve the plate redesign problem and define the optimal objective state. The latter is reached incrementally with a prediction-correction scheme without repeated finite element analyses. Systematic numerical applications in redesign of a cantilever plate of 216 degrees of freedom are used to investigate the effects of number of extracted modes and redesign variables. It is shown that the large admissible perturbations theory can be used efficiently to redesign plates for multiple specifications that require changes to the baseline design and its response of the order of 100%.

Bernitsas, Michael M.; Rim, Chae Whan

1994-05-01

356

Geology: Plate Tectonics  

NSDL National Science Digital Library

This site is the Plate Tectonics portion of the Geology site from the University of California, Berkeley, Museum of Paleontology. This exhibit has a section devoted to the explanation of the history of plate tectonics and a section that focuses on the mechanisms driving plate tectonics. The mechanisms section discusses convection, mid-oceanic ridges, geomagnetic anomalies, deep sea trenches, and island arcs. The site also contains links to numerous animations illustrating historical plate positions and movements.

357

Plate Tectonics: Moving Middle School Science  

NSDL National Science Digital Library

This resource guide from the Middle School Portal 2 project, written specifically for teachers, provides links to exemplary resources including background information, lessons, career information, and related national science education standards. This wiki page is about plate tectonics and features online resources that were hand-picked for middle school teachers. The resources are organized into three sets: background information (for teachers and students), activities (single-day and multiple-day), and animations. National Science Education Standards related to plate tectonics are also provided. Each resource set begins with a discussion of its strengths. For example, students work with models and data in the activities, many of which are discovery-oriented. Teaching tips and usage suggestions are offered in the set introductions and in the descriptions of individual resources. Together, the resources address topics such as the development of the plate tectonics theory and the types of plate boundaries and their locations.

Barber, Carolee; Ridgway, Judith

2004-11-01

358

Far infrared transmission of a thick TGS single crystal at 7K, and beers' law validity  

Microsoft Academic Search

Far IR transmission of a thick Triglycine Sulfate (TGS) single crystal t=8 mm thick is compared with calculations using the absorption index measured with a very thin t=13 µm thick plate. Big discrepancies suggest the occurence of surface layers.

X. Gerbaux; H. Marin Cudraz

1990-01-01

359

Optimal truss plates  

Microsoft Academic Search

Sandwich plates comprised of truss cores faced with either planar trusses or solid sheets are optimally designed for minimum weight subject to prescribed combinations of bending and transverse shear loads. Motivated by recent advances in manufacturing possibilities, attention is focussed on plates with truss elements and faces made from a single material. The optimized plates are compared with similarly optimized

Nathan Wicks; John W Hutchinson

2001-01-01

360

Plate Tectonic Theory  

NSDL National Science Digital Library

This is the web site for a Plate Tectonics Theory class at The University of Nevada, Reno. The home page/syllabus contains links to several of the topics covered in the course. The topics with web based lecture materials are earthquake seismology, structure of the Earth, composition of the Earth, lithospheric deformation, the plate tectonics paradigm, and the driving mechanisms of plate tectonics.

Louie, John

361

Earthquakes and Plate Tectonics  

NSDL National Science Digital Library

This article describes the theory of plate tectonics and its relation to earthquakes and seismic zones. Materials include an overview of plate tectonics, a description of Earth's crustal plates and their motions, and descriptions of the four types of seismic zones.

362

Stability and Vibration of Isotropic, Orthotropic and Laminated Plates According to a Higher-Order Shear Deformation Theory.  

National Technical Information Service (NTIS)

A higher-order shear deformation theory is used to determine the natural frequencies and buckling loads of elastic plates. The theory accounts for parabolic distribution of the transverse shear strains through the thickness of the plate and rotary inertia...

J. N. Reddy N. D. Phan

1985-01-01

363

78 FR 30271 - Stainless Steel Plate in Coils From Belgium, South Africa, and Taiwan: Notice of Court Decision...  

Federal Register 2010, 2011, 2012, 2013

...Steel Plate in Coils From Belgium, South Africa, and Taiwan: Notice of Court...in coils (SSPC) from Belgium, South Africa, and Taiwan with a nominal thickness...Plate in Coils from Belgium and South Africa; and Notice of...

2013-05-22

364

EFFECT OF PITTING CORROSION ON ULTIMATE STRENGTH AND BUCKLING STRENGTH OF PLATES - A REVIEW  

Microsoft Academic Search

The plate structures have become a great importance of study due to their wide use in field of marine and offshore structure. Moreover, in several structural engineering applications, the thickness of the plate used has a variable thickness mainly resulted from metal surface losses due to corrosion .Out of all deteriorating factors, the main focus is on corrosion because they

A. ADHITHYA PLATO SIDHARTH

365

Nonlinear analysis of FGM plates under pressure loads using the higher-order shear deformation theories  

Microsoft Academic Search

In this study, the energy concept along with the first- and third-order shear deformation theories (FSDT and TSDT) are used to predict the large deflection and through the thickness stress of FGM plates. These responses are studied and discussed as a function of plate thickness and the order “n” of a power law function which is considered for the through

R. Sarfaraz Khabbaz; B. Dehghan Manshadi; A. Abedian

2009-01-01

366

Screen test for cadmium and nickel plates  

NASA Technical Reports Server (NTRS)

A new procedure is described which was recently developed to quantify loading uniformity of nickel and cadmium plates and to screen finished electrodes prior to cell assembly. The technique utilizes the initial solubility rates of the active material in a standard chemical deloading solution at fixed conditions. The method can provide a reproducible indication of plate loading uniformity in situations where high surface loading limits the free flow of deloading solution into the internal porosity of the sinter plate. A preliminary study indicates that 'good' cell performance is associated with higher deloading rates.

Phan, Angie H.; Zimmerman, Albert H.

1994-01-01

367

Design of MM-wave Fresnel zone plate reflector antenna with continuous phase structure  

Microsoft Academic Search

The phase Fresnel zone plate, whose diffraction efficiency is up 97%, has been made. Because of the advantages of thinner thickness, lighter weight and design flexibility, the phase Fresnel zone plate has been considered for use as a MM-wave antenna so as to increase the diffraction efficiency. However, zone plates with only four phase steps are generally made up to

Fan Zhongwei; Lu Zhenwu; Liao Jianghong; Zhang Junrong; Chen Fangyun

1997-01-01

368

Finite strip analysis of anisotropic laminated composite plates using higher-order shear deformation theory  

Microsoft Academic Search

In the present study, a finite strip method for the elastic analysis of anisotropic laminated composite plates is developed according to higher-order shear deformation theory. This theory accounts for the parabolic distribution of the transverse shear strains through the thickness of the plate and for zero transverse shear stresses on the plate surfaces. In comparison with the finite strip method

G. Akhras; M. S. Cheung; W. Li

1994-01-01

369

Active control of FGM plates with integrated piezoelectric sensors and actuators  

Microsoft Academic Search

In this paper, a finite element formulation based on the classical laminated plate theory is presented for the shape and vibration control of the functionally graded material (FGM) plates with integrated piezoelectric sensors and actuators. The properties of the FGM plates are functionally graded in the thickness direction according to a volume fraction power law distribution. A constant velocity feedback

X. Q. He; T. Y. Ng; S. Sivashanker; K. M. Liew

2001-01-01

370

Postbuckling of FGM plates with piezoelectric actuators under thermo-electro-mechanical loadings  

Microsoft Academic Search

A postbuckling analysis is presented for a simply supported, shear deformable functionally graded plate with piezoelectric actuators subjected to the combined action of mechanical, electrical and thermal loads. The temperature field considered is assumed to be of uniform distribution over the plate surface and through the plate thickness and the electric field considered only has non-zero-valued component EZ. The material

Hui-Shen Shen

2005-01-01

371

The optimum arrangement of the plates in a multi-layered shield  

Microsoft Academic Search

A normal impact of a three-dimensional rigid conical impactor penetrating into a layered shield is studied using a simplified model for an impactor–shield interaction. The shield consists of adjacent plates manufactured from one of two possible materials, and the total thickness of the plates manufactured from every material is given. It is found that advancing any plate inside a shield

G. Ben-Dor; A. Dubinsky; T. Elperin

2000-01-01

372

Development and Optimization of Pulse Plating of Copper Films for MEMS Applications  

Microsoft Academic Search

High-aspect-ratio copper structures are important in the fabrication of heat dissipaters, heat sinks and radio frequency (RF) antennas among many other microelectromechanical systems (MEMS) devices. Electroplating is a preferred technique for coating thick films (> 1 µm) on metallic surfaces. The properties of the plated films are improved by the use of pulse plating. In pulse plating, the potential or

Merine Zinsou

373

A Baffle Plate For Subsurface Acoustic Module In High Ship-noise Operation  

Microsoft Academic Search

Development of a baffle plate useful for: shielding a subsurface acoustic module from high acoustic noise of a surface ship is described. The baffle plate was made of 12.7 cm (5”) thick steel plate, octagonal in shape with a 1 m diagonal length. The lower surface was covered with a layer of an acoustic absorption material, SAPER-DTM. A test was

Ham Matsumoto; Edward Noda; J. Sharkey; Frank McHale

1991-01-01

374

Solderability and environmental testing of Sn-plated surfaces  

SciTech Connect

The effect of atmospheric corrosion on the solderability of Sn plated surfaces was evaluated with 60Sn-40Pb solder. Tin thicknesses of 10, 50, and 150 {mu}in on Ni plated Cu were studied. The 10 {mu}in. plating gave the smallest solder meniscus rise. A general decrease in contact angle, or increase in wettability, was observed with increasing Sn plating. The environmental exposures retarded the wetting rate and increased the time to maximum wetting, particularly with only 10 {mu}in. of Sn. Although the solderability of the 50 and 150 {mu}in. surfaces wee not significantly affected by the test conditions, an intermediate plating thickness of 100 {mu}in. is preferred for processing flexibility. 13 refs., 7 figs., 1 tab.

Sorensen, N.R.; Hosking, F.M.

1990-01-01

375

Thick Film Glasses.  

National Technical Information Service (NTIS)

The technicA1 literature was reviewed in order to characterize the thermal expansion, viscosity, surface tension and wetting behavior as functions of composition for glasses of present or potential use in thick film formulations. The applicability of the ...

R. W. Vest

1978-01-01

376

Behavior of laminated composite plates with piezoelectric elements  

NASA Astrophysics Data System (ADS)

A finite element formulation based on higher-order shear deformation theory is presented for modeling the behavior of laminated composite plates with piezoelectric elements under static and dynamic loadings. This model is valid for both continuous and segmented piezoelectric elements that are either surface-bonded or embedded in the laminated plate. Voltage is not introduced as an additional degree of freedom in the present model and the piezoelectric elements on the upper and lower surfaces of the plate are used as actuators. The effect of actuator voltage on the static and dynamic behavior of such plates having different edge conditions and width-to-thickness ratio has been studied.

Latheswary, S.; Valsarajan, K. V.; Sadasiva Rao, Y. V. K.

2003-10-01

377

Thick frequency selective surfaces  

Microsoft Academic Search

As an additional means of controlling bandwidth, the use of periodic screens in free space with thick metallization was investigated for single-square loop and double-concentric-square loop elements. These loops elements were chosen because the passbands of such screens, with tight lattice spacing, display a remarkable insensitivity to incident polarization and angle of incidence. The effect of thick metallization on passband

D. B. Webb; E. Michielssen; R. Mittra

1992-01-01

378

Quantitative morphology of the subchondral plate of the tibial plateau.  

PubMed Central

The object of the present investigation was to measure the thickness distribution of the subchondral plate of the tibial plateau. The data were obtained by computerised image analysis of serial sections. The measured values revealed a marked difference in the thickness between the various regions of the joint surface. Thinner zones (100-300 microns) are found in the peripheral region near the margin of the tibial plateau. Thickness maxima (up to 1500 microns and more) are to be seen at the centres of the joint surfaces. The relationship between the thickness distribution of the subchondral plate and information about the stress distribution of this particular joint surface support the conclusion that the morphology of the subchondral plate of the tibial plateau is determined by the function of the joint. Images Fig. 2 Fig. 3

Milz, S; Putz, R

1994-01-01

379

Optimal interaction of indenter with inhomogeneous plate  

NASA Technical Reports Server (NTRS)

Consideration is given to a new class of problems dealing with an optimal design of an inhomogeneous plate during dynamic penetration of the rigid indenter. The quality criterion of the process is defined by the specific mass of the target, which absorbs the given kinetic mass of the indenter. Parameters of control are expressed in terms of mechanical characteristics, i.e., distribution of density and the related hardness across the plate thickness. The maximum principle of Pontryagin is used to search for the piecewise continuous control function. With consideration of impact conditions and characteristics for a given class of material, an optimal target structure criterion was estimated for engineering applications.

Aptukov, Valery N.

1991-01-01

380

Fabrication of Fresnel zone plates with high aspect ratio by soft X-ray lithography  

Microsoft Academic Search

High focusing efficiency Fresnel zone plates for hard X-ray imaging is fabricated by electron beam lithography, soft X-ray\\u000a lithography, and gold electroplating techniques. Using the electron beam lithography, Fresnel zone plates which has an outermost\\u000a zone width of 100 nm and thickness of 250 nm has been fabricated. Fresnel zone plates with outermost zone width of 150 nm\\u000a and thickness of 660 nm has

Longhua Liu; Gang Liu; Ying Xiong; Jie Chen; Chunlei Kang; Xinlong Huang; Yangchao Tian

2008-01-01

381

Experimental and theoretical analyses on laser-generated transient Lamb waves in an orthotropic plate  

Microsoft Academic Search

The technique of laser-generated and laser-detected Lamb waves is a powerful tool for characterizing elastic property of plates. However, the transient waveforms depend strongly on the longitudinal acoustic wavelength L and the plate thickness H. For a thick plate (bulk material), L\\/H≪1, a typical waveform consists of arrivals of longitudinal, shear, and surface wave pulses, if a detecting position is

J. C. Cheng; S. Y. Zhang; Y. Berthelot

2000-01-01

382

Experimental and theoretical analyses on laser-generated transient Lamb waves in an orthotropic plate  

Microsoft Academic Search

The technique of laser-generated and laser-detected Lamb waves is a powerful tool for characterizing elastic property of plates. However, the transient waveforms depend strongly on the longitudinal acoustic wavelength L and the plate thickness H. For a thick plate (bulk material), L\\/H<>1, the transient waveform is characterized by the lowest Lamb wave modes, i.e., the first arrival of the spike

J. C. Cheng; S. Y. Zhang; Y. Berthelot

2000-01-01

383

A double layer plaque assay using spread plate technique for enumeration of bacteriophage MS2.  

PubMed

Bacteriophage MS2 is used widely as a model organism to estimate pathogenic virus survival in various environments, and is usually quantified by plaque assay. Although current plaque assays work well in enumeration of MS2 in environmental samples, quantification of MS2 calls for better visibility and higher consistency. In an attempt to improve the visibility and consistency of the current plaque assay, spread plate technique was introduced, instead of the pour plate technique used commonly in existing methods. Other parameters that influence the outcome of the plaque assay were also compared. Using spread plate technique resulted in an increase of plaque size by approximately 50% and contributed to a better visibility. Addition of supplements (glucose, CaCl2 and thiamine); reduction of agar thickness and hardness, also contributed to enhanced plaque visibility and increased plaque count. Among all the conditions tested, a supplemented thin bottom agar (10ml 1% agar) and a supplemented thin top agar (10ml 0.45% agar) with spread plate technique gave the maximum countable plaques with a minimum standard deviation. When compared to other methods, it produced significantly higher plaque count and lower variation. The optimized plaque assay significantly improved visibility and consistency of the existing plaque assay methods and could be used in quantification of MS2. PMID:24211298

Cormier, Jiemin; Janes, Marlene

2014-02-01

384

Infrared vacuum soldering process for thick-film hybrid microcircuits  

Microsoft Academic Search

An infrared vacuum soldering (IVS) process was developed for thick-film hybrid microcircuits (HMC's) being manufactured at Allied-Signal Inc., Kansas City Division (KCD). Sample HMC's were assembled and destructively tested to determine the intermetallic growth of the thick-film metallization when soldered to a mounting plate using 50-indium\\/50-lead solder and 63-tin\\/37-lead solder. The large voids in a solder joint reduce the area

R. W. Brown

1993-01-01

385

Fuel Cell Thermal Management Through Conductive Cooling Plates  

NASA Technical Reports Server (NTRS)

An analysis was performed to evaluate the concept of utilizing conductive cooling plates to remove heat from a fuel cell stack, as opposed to a conventional internal cooling loop. The potential advantages of this type of cooling system are reduced stack complexity and weight and increased reliability through the reduction of the number of internal fluid seals. The conductive cooling plates would extract heat from the stack transferring it to an external coolant loop. The analysis was performed to determine the required thickness of these plates. The analysis was based on an energy balance between the thermal energy produced within the stack and the heat removal from the cooling plates. To accomplish the energy balance, the heat flow into and along the plates to the cooling fluid was modeled. Results were generated for various numbers of cells being cooled by a single cooling plate. The results provided cooling plate thickness, mass, and operating temperature of the plates. It was determined that utilizing high-conductivity pyrolitic graphite cooling plates can provide a specific cooling capacity (W/kg) equivalent to or potentially greater than a conventional internal cooling loop system.

Colozza, Anthony J.; Burke, Kenneth A.

2008-01-01

386

Materials science in pre-plated leadframes for electronic packages  

NASA Astrophysics Data System (ADS)

Au/Pd/Ni pre-plated leadframes (PPF) are high performance frames for accommodating high-end electronic packages. Cost and reliability are major concerns in their wide application. The present work, from a materials science point view, deepens the understanding of PPFs, optimizes the conventional PPFs, develops a novel PPF architecture and models the residual stress relaxation in heteroepitaxial thin films. The wire pull test, the solderability test, and High-Resolution Transmission Electron Microscopy (HRTEM) were employed to characterize the PPFs in order to understand the relationship between performance and microstructure. We optimized the electroplating profiles and determined the minimum thickness of the Pd layer with the PPF performance satisfying the industry standards. Further increasing the Pd layer thickness beyond the critical thickness will not enhance the performance more, but increase the product cost. With the optimized electroplating profile, the electroplated Au layer is epitaxially deposited on the Pd layer, and so does the Pd layer on the Ni layer. Misfit dislocations and nanotwins are present at the interface between the Pd and Ni layers, which are generated to release the about 10.4% misfit strain between the Pd and Ni lattices. This work demonstrates that the electro-deposition technique can electroplate epitaxy-like Pd films on the highly (200) textured Ni films, which are grown on the Cu substrates. A novel technique for impeding Cu out-diffusion in Cu alloy based pre-plated leadframes was developed by electroplating a 3-4 nm thick Sn layer on a Cu alloy base prior to electroplating a Ni layer. A 10-14 nm thick epitaxy-like and dense (Cu,Ni)3Sn intermetallic compound (IMC) layer is automatically formed en route of diffuse reaction, which leads to a drastic reduction in Cu out-diffusion and hence improves significantly the protection of the leadframes against oxidation and corrosion attack. The oxidation behaviours were quantified by Electron Diffraction X-ray (EX) incorporated in Scanning Electron Microscopy (SEM) in the present work, which is a good complementary to the traditional weight gain test by a balance. A diffusion/oxidation model was developed to estimate the effective diffusion coefficient of Cu in the formed IMC nanolayers. The estimated Cu diffusion coefficient in the IMC interlayer is about 1.6x10 -22m2/s at 250°C, which is around 7~11 orders lower than the interdiffusion coefficients for eta- Cu6Sn5 and epsilon- Cu3Sn phases at corresponding temperatures. Based on the dislocation theory of twinning, analytical solutions by using the hybrid superposition and Fourier transformation approach were derived for the calculation of various energies involved in the misfit twinning process. For a given epilayer thickness and lattice mismatch strain, the twin formation energy should reach its minimum to determine the twin width and a zero minimum formation energy determines the critical thickness for misfit twinning. The effect of elastic mismatch between the epilayer and the substrate on the critical thickness was studied comprehensively, revealing that an elastically soft epilayer has a large critical thickness. Moreover, a misfit-twin-and-perfect-dislocation predominance chart is constructed to predict the predominant regions of misfit twinning and perfect dislocation in the mismatch strain and the specific twin boundary energy domain. Multiple misfit twins in epilayer/substrate systems were studied by summing up the stress and displacement fields of individual twins. In principle, the energy minimization approach can be applied to multiple misfit twins, although only periodic arrays of parallel and alternating twins were investigated here in detail. The equilibrium twin width and equilibrium twin spacing of a periodic array of twins represent the misfit twin morphology. The theoretical results indicate that the difference in elastic constants between an epilayer and its substrate has great effects on the morphology of equilibrium twins. The theoretical predictions agree with experimental

Liu, Lilin

387

Sound absorption by clamped poroelastic plates.  

PubMed

Measurements and predictions have been made of the absorption coefficient and the surface acoustic impedance of poroelastic plates clamped in a large impedance tube and separated from the rigid termination by an air gap. The measured and predicted absorption coefficient and surface impedance spectra exhibit low frequency peaks. The peak frequencies observed in the absorption coefficient are close to those predicted and measured in the deflection spectra of the clamped poroelastic plates. The influences of the rigidity of the clamping conditions and the width of the air gap have been investigated. Both influences are found to be important. Increasing the rigidity of clamping reduces the low frequency absorption peaks compared with those measured for simply supported plates or plates in an intermediate clamping condition. Results for a closed cell foam plate and for two open cell foam plates made from recycled materials are presented. For identical clamping conditions and width of air gap, the results for the different materials differ as a consequence mainly of their different elasticity, thickness, and cell structure. PMID:19045646

Aygun, H; Attenborough, K

2008-09-01

388

Computational model for residual stresses in a clad plate and clad fracture specimens  

Microsoft Academic Search

This report contains the results from computed residual stresses for three stainless steel clad plate configurations. Each simulates a condition of interest to a study on the effect of surface cracks in the clad layer of reactor pressure vessels. The configurations analyzed were the as-received 118-mm thick clad plate, a 32-mm thick specimen with a full-thickness of cladding weld metal,

E. F. Rybicki; R. B. Stonesifer

1986-01-01

389

Ceramic burner plate  

SciTech Connect

This invention relates to a ceramic burner plate using a fiber composite ceramic of low thermal conductivity having gas passages, and provides a burner plate, wherein the burner plate contains a lithium component and such components as nickel, manganese, cobalt, titanium, copper, iron, chromium, and vanadium, to assist in the combustion of gas, and has a surface construction having triangular projections, hexagonal projections or rhombic projections, to ensure increased heat radiation.

Mihara, T.; Kusuda, T.; Noma, K.; Taki, H.

1985-03-12

390

Zone plate interferometer  

NASA Technical Reports Server (NTRS)

A developed form of the Fresner zone-plate interferometer is described. Three basic configurations are distinguished, associated with the real and virtual first order foci of a zone plate. Related versions and higher order variants are also educed. Compensated phase zone plates used in this application are found to produce uniform amplitude wavefronts. The properties of the interferometer in this form are discussed and an example given of its high-quality performance.

Smartt, R. N.

1974-01-01

391

Understanding Plate Motions  

NSDL National Science Digital Library

This interactive site uses illustrations and photographs along with text to explain the movement of tectonic plates and the result of this movement on the surface of the Earth. There is a detailed discussion of the movement at each of the four types of plate boundaries: divergent, convergent, transform, and plate boundary zones. Both lateral and vertical movements are depicted by maps and diagrams and resulting Earth structures are shown in photographs.

392

Localized bending waves in a transversely isotropic plate  

NASA Astrophysics Data System (ADS)

The problem of bending waves localized near the free edge of a transversely isotropic plate is investigated using the Ambartsumian higher-order plate theory which takes account of the transverse shears generated by flexural deformation. Unlike the first-order Reissner-Mindlin theory, which also takes account of transverse shears, Ambartsumian's analysis does not demand that plane normal cross-sections remain plane during bending. Within this analysis the existence of localized bending waves in transversely isotropic plates is established, and solutions of the dispersion equation obtained for different values of the elastic parameters. The analysis of frequencies of localized bending waves shows that for thick plates the effect of anisotropy can be considerable. For the particular case of vibrations of a narrow plate, from the long wave approximation a new beam vibration equation of the Timoshenko type is obtained for a transversally isotropic plate.

Piliposian, G. T.; Belubekyan, M. V.; Ghazaryan, K. B.

2010-08-01

393

Axisymmetric Bending Analysis of Two Directional Functionally Graded Circular Plates Using Third Order Shear Deformation Theory  

Microsoft Academic Search

\\u000a Bending analysis of a functionally graded circular plate with clamped and simply supported boundary conditions is carried\\u000a out. Material properties of the plate are assumed to be functionally graded in two directions, namely in the radial direction\\u000a and through the thickness of the plate, obeying exponential distribution laws. Poisson’s ratio is assumed to be constant throughout\\u000a the plate. Governing equations

Reza Akbari Alashti; Hossein Rahbari

394

Plate Motion Calculator  

NSDL National Science Digital Library

This program calculates tectonic plate motion at any location on Earth using one or more plate motion models. The possible plate motion models are GSRM v1.2 (2004), CGPS (2004), HS3-NUVEL1A, REVEL 2000, APKIM2000.0, HS2-NUVEL1A, NUVEL 1A, NUVEL 1, and two models for ITRF2000. Plates or frames are selected from dropdown lists or can be entered by the user. Position coordinates can be entered in geographic coordinates (decimal degrees, or degrees/minutes/seconds) or in WGS84 cartesian XYZ, as either a single point or multiple points.

Estey, Lou

395

Plates on the Move  

NSDL National Science Digital Library

This fun Web article is part of OLogy, where kids can collect virtual trading cards and create projects with them. Here, they learn about the Earth's outer shell and its constant movement. It begins with an overview that explains tectonic plates. There is an animation that shows recent earthquakes and their relationship to plate boundaries. Students can click to explore 12 individual volcanoes, mountains, hotspots, and earthquakes. For each of the geological formations or events, they will see a map that shows how the plates are moving, an animation about plate interaction, stats, and a story about that particular formation or event.

396

Influence of filter thickness on PESA calibration  

NASA Astrophysics Data System (ADS)

Elemental analysis of air particulate matter collected on Teflon filters using ion beam analysis (IBA) allows simultaneous analysis of the hydrogen content. Hydrogen is determined by a method known as particle elastic scattering analysis (PESA). The hydrogen concentration in the air particulate matter samples is determined by comparing the ratio of the hydrogen peak yield to the yields from standards of known hydrogen composition. The study presented in this paper shows that this process can be inaccurate if the calibration standards used are of different thicknesses compared to the air pollution samples. A series of experiments were undertaken to investigate the effect of sample and standard thickness on the determination of hydrogen concentrations. It was found that the filter thickness and the distribution of the air particulate matter within the filter significantly affected the yield of the hydrogen peak in the PESA spectra. Therefore, it is important to consider the effect of thickness and the distribution of the hydrogen in both the calibration standards and the sample filters for PESA analysis.

Trompetter, W. J.; Davy, P.; Barry, B.; Kennedy, J.

2014-08-01

397

Mannheim Intima-Media Thickness Consensus  

Microsoft Academic Search

Intima-media thickness (IMT) is increasingly used in clinical trials as a surrogate end point for determining the success of interventions that lower risk factors for atherosclerosis. The necessity for unified criteria to distinguish early atherosclerotic plaque formation from thickening of IMT and to standardize IMT measurements is addressed in this consensus statement. Plaque is defined as a focal structure that

P.-J. Touboul; M. G. Hennerici; S. Meairs; H. Adams; P. Amarenco; M. Desvarieux; S. Ebrahim; M. Fatar; R. Hernandez Hernandez; S. Kownator; P. Prati; T. Rundek; A. Taylor; N. Bornstein; L. Csiba; E. Vicaut; K. S. Woo; F. Zannad

2004-01-01

398

Localized vibrational modes in bars and plates  

NASA Astrophysics Data System (ADS)

We consider the localized vibrational modes that can exist at the edge of a semi-infinite plate and at the end of a semi-infinite bar of small thickness. It is known that for certain special values of Poisson's ratio ? these modes are perfectly localized, are uncoupled to bulk modes, and thus do not lose energy by acoustic radiation. We show that for other values of ? it is possible to modify the shape of the end of the plate or bar in a way such that a perfectly localized edge mode is formed. Finally, we discuss the effect of this localization phenomenon on the vibrational modes of plates and bars of finite length.

Ma, Jing; Maris, Humphrey J.

2010-05-01

399

Diffusion of copper into gold plating  

Microsoft Academic Search

The value of the room-temperature copper-gold interdiffusion coefficient derived by extrapolating from high-temperature measurements is an underestimate by several orders of magnitude. Plating copper with a gold film has several disadvantages. Two specimens were analyzed by using Auger electron spectroscopy. Once the full thickness of the gold film is penetrated, copper accumulates on the surface, and a layer of high

Sunchana P. Pucic

1993-01-01

400

Improved genetic algorithm for minimum thickness composite laminate design  

Microsoft Academic Search

The use of a genetic algorithm for the minimum thickness design of composite laminated plates is explored. A previously developed genetic algorithm for laminate design is thoroughly revised and improved, by incorporating knowledge of the physics of the problem into the genetic algorithm. Constraints are accounted for by combining fixed and progressive penalty functions. Improved selection, mutation, and permutation operators

R. Le Riche; R. T. Haftka

1995-01-01

401

Thick Film Interference.  

ERIC Educational Resources Information Center

Discusses why interference effects cannot be seen with a thick film, starting with a review of the origin of interference patterns in thin films. Considers properties of materials in films, properties of the light source, and the nature of light. (JN)

Trefil, James

1983-01-01

402

40 CFR 426.40 - Applicability; description of the plate glass manufacturing subcategory.  

Code of Federal Regulations, 2013 CFR

...Applicability; description of the plate glass manufacturing subcategory. 426.40 Section 426...GUIDELINES AND STANDARDS (CONTINUED) GLASS MANUFACTURING POINT SOURCE CATEGORY Plate Glass Manufacturing Subcategory § 426.40...

2013-07-01

403

Industrialization of the ion plating process  

NASA Technical Reports Server (NTRS)

A new process referred to as ion plating by induction heating (IPIH) is described, which combines the advantages of both ion plating and induction heating. The IPIH apparatus consists of the specimen (cathode) to be coated and the evaporation heating source, which is a ceramic crucible containing the metal to be heated. The specimen is an internal part of the high-voltage ceramic-metal vacuum feedthrough and is connected to the negative terminal of the high-voltage power supply, the positive terminal of the power supply being grounded. The plating conditions are the same as those most commonly used in industrial ion plating. A number of metals - such as nickel, iron, platinum - which were practically impossible to deposit by resistance heating evaporation can now be effectively evaporated and deposited to any desired thickness. Excellent adherence is observed for many metals deposited on various metal surfaces in thicknesses from 0.15 to 50 microns, regardless of the materials selected for coating and substrate.

Spalvins, T.

1976-01-01

404

Proposed Method for Determining the Thickness of Glass in Solar Collector Panels.  

National Technical Information Service (NTIS)

An analytical method was developed for determining the minimum thickness for simply supported, rectangular glass plates subjected to uniform normal pressure environmental loads such as wind, earthquake, snow, and deadweight. The method consists of compari...

D. M. Moore

1980-01-01

405

Plates and their motions  

NASA Technical Reports Server (NTRS)

Work on plate motions published in 1983-1986 and in early 1987 is reviewed. Models for these motions, including global ones for driving forces and local ones for subduction history and back-arc spreading, are addressed. The problem of reference frames, both hotspot and paleomagnetic, is discussed. The assessment of errors in plate motion studies is reviewed.

Jurdy, Donna M.

1987-01-01

406

Magnitogorsk Armor Plate.  

National Technical Information Service (NTIS)

This is a sketch of how the metallurgists at the Magnitogorsk (Magnitka) steel factory in the Soviet Union fulfilled the Soviet Union's need for armor plate during World War II. Since no mills for rolling armor plate existed in Magnitka before the war, en...

Y. Petrov

1968-01-01

407

Polygonal Fresnel zone plates  

Microsoft Academic Search

The performance of Fresnel zone plates having a polygonal boundary between zones has been studied. The contribution of the complex amplitude of each zone is calculated analytically and numerically solved. The case of a continuous phase plate is considered as the limit case in performance for each polygonal shape. This performance is compared with respect to the circular case. Also

Javier Alda; Francisco Javier González

2009-01-01

408

Blue Willow Story Plates  

ERIC Educational Resources Information Center

In the December 1997 issue of "SchoolArts" is a lesson titled "Blue Willow Story Plates" by Susan Striker. In this article, the author shares how she used this lesson with her middle-school students many times over the years. Here, she describes a Blue Willow plate painting project that her students made.

Fontes, Kris

2009-01-01

409

Internet Geography: Plate Tectonics  

NSDL National Science Digital Library

This site is part of GeoNet Internet Geography, a resource for pre-collegiate British geography students and their instructors. This page focuses on the structure of the Earth and the theory of plate tectonics, including continental drift, plate boundaries, the Ring of Fire, and mountains.

410

Wave propagation of functionally graded material plates in thermal environments.  

PubMed

The wave propagation of an infinite functionally graded plate in thermal environments is studied using the higher-order shear deformation plate theory. The thermal effects and temperature-dependent material properties are both taken into account. The temperature field considered is assumed to be a uniform distribution over the plate surface and varied in the thickness direction only. Material properties are assumed to be temperature-dependent, and graded in the thickness direction according to a simple power law distribution in terms of the volume fractions of the constituents. Considering the effects of transverse shear deformation and rotary inertia, the governing equations of the wave propagation in the functionally graded plate are derived by using the Hamilton's principle. The analytic dispersion relation of the functionally graded plate is obtained by solving an eigenvalue problem. Numerical examples show that the characteristics of wave propagation in the functionally graded plate are relates to the volume fraction index and thermal environment of the functionally graded plate. The influences of the volume fraction distributions and temperature on wave propagation of functionally graded plate are discussed in detail. The results carried out can be used in the ultrasonic inspection techniques and structural health monitoring. PMID:21663930

Sun, Dan; Luo, Song-Nan

2011-12-01

411

Heterotrophic plate count methodology in the United States.  

PubMed

In the United States (US), the history of bacterial plate counting (BPC) methods used for water can be traced largely through Standard Methods for the Examination of Water and Wastewater (Standard Methods). The bacterial count method has evolved from the original Standard Methods (1st edition, 1905) plate count which used nutrient gelatin and incubation at 20 degrees C for 48 h, to the HPC method options in the latest edition of Standard Methods that provide greater flexibility of application, depending on the data needs of the water analyst. The use of agar-agar as a gelling agent, replacing gelatin, allowed the use of higher incubation temperatures and resulted in the "body temperature count" (37 degrees C) found in the 3rd through the 8th edition of Standard Methods. The change from 37 degrees C incubation to 35+/-0.5 degrees C accommodated laboratories that did both milk and water analyses. By using a single temperature, fewer incubators were needed. The term "standard plate count" (SPC) first appeared in 1960 (11th edition) along with plate count agar. Incubation at 20 degrees C for the plate count was dropped from the 13th to 15th editions and few changes were made in the SPC method from the 11th edition through the 13th editions. Plate count analysis of bottled waters was included in the 14th edition (1975), calling for incubation at 35+/-0.5 degrees C for 72+/-4 h. Perhaps the most significant changes in plate count methods occurred with the 16th edition (1985). The term heterotrophic plate count replaced the standard plate count, and the spread plate (SP) and membrane filter (MF) methods were added along with new media for pour and spread plates (R2A agar and NWRI agar, both low nutrient) and for the membrane filter method (mHPC medium). The use of low nutrient media, lower incubation temperature, and longer incubation times, results in higher plate count results for most water samples. The options currently available, including low and high nutrient media, incubation temperatures (20 degrees C, 28 degrees C or 35 degrees C), plating methods (pour plate (PP), spread plate and membrane filter) and range of incubation times (24, 48, 72 h and 5-7 days) provide great flexibility in the application of the HPC analysis to drinking water. PMID:15145589

Reasoner, Donald J

2004-05-01

412

Fashion Plate Collection  

NSDL National Science Digital Library

There are fashion plates, and then there are the exquisite fashion plates that constitute the University of Washington Libraries digitized collection. The plates were first collected by long-time home economics professor Blanche Payne, who taught at the University from 1927 to 1966. The plates come from leading French, American, and British fashion journals of the 19th and early 20th century and they document many stylistic periods, such as the Empire, Romantic, Victorian, and Edwardian. Visitors will want to start by reading an essay on the collection, and then they should feel welcome to browse the collection of over 400 plates at their leisure, or to browse the collection by subject. One fascinating aspect of the site is an extended excerpt from the 1913 book "Dame fashion" which comments on the history and transformation of various fashions during the 19th century.

413

COMPPAP - COMPOSITE PLATE BUCKLING ANALYSIS PROGRAM (UNIX VERSION)  

NASA Technical Reports Server (NTRS)

The Composite Plate Buckling Analysis Program (COMPPAP) was written to help engineers determine buckling loads of orthotropic (or isotropic) irregularly shaped plates without requiring hand calculations from design curves or extensive finite element modeling. COMPPAP is a one element finite element program that utilizes high-order displacement functions. The high order of the displacement functions enables the user to produce results more accurate than traditional h-finite elements. This program uses these high-order displacement functions to perform a plane stress analysis of a general plate followed by a buckling calculation based on the stresses found in the plane stress solution. The current version assumes a flat plate (constant thickness) subject to a constant edge load (normal or shear) on one or more edges. COMPPAP uses the power method to find the eigenvalues of the buckling problem. The power method provides an efficient solution when only one eigenvalue is desired. Once the eigenvalue is found, the eigenvector, which corresponds to the plate buckling mode shape, results as a by-product. A positive feature of the power method is that the dominant eigenvalue is the first found, which is this case is the plate buckling load. The reported eigenvalue expresses a load factor to induce plate buckling. COMPPAP is written in ANSI FORTRAN 77. Two machine versions are available from COSMIC: a PC version (MSC-22428), which is for IBM PC 386 series and higher computers and compatibles running MS-DOS; and a UNIX version (MSC-22286). The distribution medium for both machine versions includes source code for both single and double precision versions of COMPPAP. The PC version includes source code which has been optimized for implementation within DOS memory constraints as well as sample executables for both the single and double precision versions of COMPPAP. The double precision versions of COMPPAP have been successfully implemented on an IBM PC 386 compatible running MS-DOS, a Sun4 series computer running SunOS, an HP-9000 series computer running HP-UX, and a CRAY X-MP series computer running UNICOS. COMPPAP requires 1Mb of RAM and the BLAS and LINPACK math libraries, which are included on the distribution medium. The COMPPAP documentation provides instructions for using the commercial post-processing package PATRAN for graphical interpretation of COMPPAP output. The UNIX version includes two electronic versions of the documentation: one in LaTex format and one in PostScript format. The standard distribution medium for the PC version (MSC-22428) is a 5.25 inch 1.2Mb MS-DOS format diskette. The standard distribution medium for the UNIX version (MSC-22286) is a .25 inch streaming magnetic tape cartridge (Sun QIC-24) in UNIX tar format. For the UNIX version, alternate distribution media and formats are available upon request. COMPPAP was developed in 1992.

Smith, J. P.

1994-01-01

414

COMPPAP - COMPOSITE PLATE BUCKLING ANALYSIS PROGRAM (IBM PC VERSION)  

NASA Technical Reports Server (NTRS)

The Composite Plate Buckling Analysis Program (COMPPAP) was written to help engineers determine buckling loads of orthotropic (or isotropic) irregularly shaped plates without requiring hand calculations from design curves or extensive finite element modeling. COMPPAP is a one element finite element program that utilizes high-order displacement functions. The high order of the displacement functions enables the user to produce results more accurate than traditional h-finite elements. This program uses these high-order displacement functions to perform a plane stress analysis of a general plate followed by a buckling calculation based on the stresses found in the plane stress solution. The current version assumes a flat plate (constant thickness) subject to a constant edge load (normal or shear) on one or more edges. COMPPAP uses the power method to find the eigenvalues of the buckling problem. The power method provides an efficient solution when only one eigenvalue is desired. Once the eigenvalue is found, the eigenvector, which corresponds to the plate buckling mode shape, results as a by-product. A positive feature of the power method is that the dominant eigenvalue is the first found, which is this case is the plate buckling load. The reported eigenvalue expresses a load factor to induce plate buckling. COMPPAP is written in ANSI FORTRAN 77. Two machine versions are available from COSMIC: a PC version (MSC-22428), which is for IBM PC 386 series and higher computers and compatibles running MS-DOS; and a UNIX version (MSC-22286). The distribution medium for both machine versions includes source code for both single and double precision versions of COMPPAP. The PC version includes source code which has been optimized for implementation within DOS memory constraints as well as sample executables for both the single and double precision versions of COMPPAP. The double precision versions of COMPPAP have been successfully implemented on an IBM PC 386 compatible running MS-DOS, a Sun4 series computer running SunOS, an HP-9000 series computer running HP-UX, and a CRAY X-MP series computer running UNICOS. COMPPAP requires 1Mb of RAM and the BLAS and LINPACK math libraries, which are included on the distribution medium. The COMPPAP documentation provides instructions for using the commercial post-processing package PATRAN for graphical interpretation of COMPPAP output. The UNIX version includes two electronic versions of the documentation: one in LaTex format and one in PostScript format. The standard distribution medium for the PC version (MSC-22428) is a 5.25 inch 1.2Mb MS-DOS format diskette. The standard distribution medium for the UNIX version (MSC-22286) is a .25 inch streaming magnetic tape cartridge (Sun QIC-24) in UNIX tar format. For the UNIX version, alternate distribution media and formats are available upon request. COMPPAP was developed in 1992.

Smith, J. P.

1994-01-01

415

40 CFR Table 1 to Subpart Wwwwww... - Table 1 to Subpart WWWWWW of Part 63. Applicability of General Provisions to Plating and...  

Code of Federal Regulations, 2010 CFR

...Applicability of General Provisions to Plating and Polishing Area Sources 1 Table 1 to...Applicability of General Provisions to Plating and Polishing Area Sources Protection of Environment...Pollutants: Area Source Standards for Plating and Polishing Operations Pt. 63,...

2009-07-01

416

40 CFR Table 1 to Subpart Wwwwww... - Table 1 to Subpart WWWWWW of Part 63. Applicability of General Provisions to Plating and...  

Code of Federal Regulations, 2010 CFR

...Applicability of General Provisions to Plating and Polishing Area Sources 1 Table 1 to...Applicability of General Provisions to Plating and Polishing Area Sources Protection of Environment...Pollutants: Area Source Standards for Plating and Polishing Operations Pt. 63,...

2010-07-01

417

Standardization versus Standards.  

ERIC Educational Resources Information Center

Examines differences between old state-designed norm-referenced tests and new tests aligned with the curriculum. Concludes that new state tests are very similar to old ones. Discusses impact of new high-stakes standardized tests on students and teachers. Argues the new wave of standardized testing is not the answer to improving student…

Meier, Deborah

2002-01-01

418

Imaging performance of microsphere plates  

NASA Astrophysics Data System (ADS)

The microsphere plate (MSP) is a new type of electron multiplier device operating along similar lines to the well known microchannel plate (MCP). The MSP is manufactured by El- Mul Technologies Ltd., using glass beads 20 to 60 micrometer diameter, sintered together to form a wafer less than 1 mm thick. Conductive coatings are applied to the upper and lower surfaces, and a high voltage is applied between these two electrodes, allowing secondary electron multiplication to take place. The device uses the surfaces of the randomly arranged interstices of the sintered glass beads as dynodes, whereas in the MCP, dynodes are constituted by the inner surfaces of the longitudinal pores. The homogeneous composition of the MSP causes charge to spread laterally during multiplication, resulting in a spatial resolution of about 2 line pairs/mm when proximity focused to a phosphor. Charge division readouts benefit from this charge spreading, such as the wedge and strip anode which requires a charge footprint of order 1 - 2 mm diameter. We present results of experiments on the imaging performance of detectors using MSPs with readouts such as the wedge and strip anode. We discuss and quantify the potential advantages to be gained from MSPs, such as the higher gain achievable per stage, reduced susceptibility to paralysis owing to their isotropic conductivity, etc. Potential MSP disadvantages, such as image nonlinearities, quantum efficiency variability, and pulse height saturation are analyzed.

Lapington, Jonathan S.; Worth, L. B.; Trow, Matthew W.

1995-09-01

419

Solderability of environmentally exposed Sn-plated surfaces  

SciTech Connect

Solderability of Class II environmentally exposed Ni-Sn plated Cu substrates was evaluated with 60Sn-40Pb solder. Tin thickness were 10, 50, and 150 {mu}in. The 10 {mu}in. plating gave the smallest solder meniscus rise. A general decrease in contact angle, or increase in wettability, was observed with increasing Sn plating. The environmental exposures retarded the wetting rate and increased the time to maximum wetting, particularly with only 10 {mu}in. of Sn. Although the solderability of the 50 and 150 {mu}in. surfaces were not significantly affected by the test conditions, an intermediate plating thickness of 100 {mu}in. is preferred for processing flexibility. 13 refs., 6 figs., 1 tab.

Hosking, F.M.; Sorensen, N.R.

1990-01-01

420

Observations of plate martensite in a low carbon steel  

SciTech Connect

It has long been known that there are two predominant morphologies of martensite in steels. These morphologies are currently referred to as plate martensite and lath martensite and are primarily distinguished by the size and shape of individual martensite grains. Plate martensite is typically several microns thick and tens of microns in diameter, while lath martensite is typically less than one-half micron thick, a few microns wide, and tens of microns long. This paper presents evidence of a coarse plate-shaped martensite morphology in a commercial HSLA-100 steel which contains only 0.07% carbon. This morphology was discovered during microstructural characterization of specimens thermally cycled to simulate weld heat affected zones in a steel plate and was reproduced in other specimens subjected to a quench and temper heat treatment.

Fonda, R.W.; Spanos, G.; Vandermeer, R.A. (Naval Research Lab., Washington, DC (United States))

1994-09-15

421

Intro to Plate Tectonic Theory  

NSDL National Science Digital Library

This website from PBS provides information about the plate tectonics, the theory that the Earth's outer layer is made up of plates, which have moved throughout time. The four types of plate boundaries are described and illustrated with animations. The first page of plate tectonics also provides a plate tectonics activity and information about related people and discoveries.

2008-05-28

422

Plate Tectonics: A Continuous Process  

NSDL National Science Digital Library

This page provides an introduction to plate tectonics for secondary students. Topics include plate motions, the layers of the Earth and oceanic versus continental plates. A set of links provides access to material on the processes of plate tectonics occuring at plate boundaries, zones of movement and instability.

423

Effect of adhesive thickness on adhesively bonded T-joint  

NASA Astrophysics Data System (ADS)

The aim of this work is to analyze the effect of adhesive thickness on tensile strength of adhesively bonded stainless steel T-joint. Specimens were made from SUS 304 Stainless Steel plate and SUS 304 Stainless Steel perforated plate. Four T-joint specimens with different adhesive thicknesses (0.5, 1.0, 1.5 and 2.0 mm) were made. Experiment result shows T-joint specimen with adhesive thickness of 1.0 mm yield highest maximum load. Identical T-joint specimen jointed by spot welding was also tested. Tensile test shows welded T-Joint had eight times higher tensile load than adhesively bonded T-joint. However, in low pressure application such as urea granulator chamber, high tensile strength is not mandatory. This work is useful for designer in fertilizer industry and others who are searching for alternative to spot welding.

Abdullah, A. R.; Afendi, Mohd; Majid, M. S. Abdul

2013-12-01

424

Comparison of plate count agar and R2A medium for enumeration of heterotrophic bacteria in natural mineral water  

Microsoft Academic Search

In order to recover as many viable bacteria as possible from natural mineral water, in this study we have compared the counts obtained with the standard method (pour plate procedure with Plate Count Agar (PCA)) and counts with alternative test methods (PCA\\/spread plates, R2A medium\\/pour plates and R2A medium\\/spread plates). The results showed that counts with R2A medium\\/spread plates at

Salvatore Massa; Marisa Caruso; Francesca Trovatelli; Massimo Tosques

1998-01-01

425

Thick film conductor compositions  

Microsoft Academic Search

A copper-containing thick film conductor composition comprising a mixture of finely divided particles of a conductive material containing copper metal, inorganic binder and 0.2-5% wt. of a noncuprous metal selected from the group consisting of tungsten, molybdenum, rhenium and alloys and mixtures thereof all dispersed in organic medium. The metal particles must be within certain narrow ranges of particle size.

Siuta

1985-01-01

426

Gold thick film conductors  

Microsoft Academic Search

Conventional thick film conductors rely for their adhesion on the formation of a glassy layer which keys them both chemically\\u000a and mechanically to the substrate surface. A newer type of conductor contains no glass frit but is reactively-bonded to the\\u000a substrate, resulting in different properties which may be advantageous for certain applications. This article is based upon\\u000a a contribution presented

M. V. Coleman; G. E. Gurnett

1977-01-01

427

Compression Behaviors of Thickness-Reduced Steel Pipes Repaired with Underwater Welds  

Microsoft Academic Search

Underwater welding is commonly used to repair corroded offshore steel structures. Corrosion-damaged portions are covered by welded patch plates. According to the current design manual, a thickness of patch plate and a weld length can be determined. However, different weld patterns can be designed to achieve the same required weld length. In order to examine the effectiveness of these different

X. Chen; Y. Kitane; Y. Itoh

2011-01-01

428

Thick brane solutions  

NASA Astrophysics Data System (ADS)

This paper gives a comprehensive review on thick brane solutions and related topics. Such models have attracted much attention from many aspects since the birth of the brane world scenario. In many works, it has been usually assumed that a brane is an infinitely thin object; however, in more general situations, one can no longer assume this. It is also widely considered that more fundamental theories such as string theory would have a minimal length scale. Many multidimensional field theories coupled to gravitation have exact solutions of gravitating topological defects, which can represent our brane world. The inclusion of brane thickness can realize a variety of possible brane world models. Given our understanding, the known solutions can be classified into topologically non-trivial solutions and trivial ones. The former class contains solutions of a single scalar (domain walls), multi-scalar, gauge-Higgs (vortices), Weyl gravity and so on. As an example of the latter class, we consider solutions of two interacting scalar fields. Approaches to obtain cosmological equations in the thick brane world are reviewed. Solutions with spatially extended branes (S-branes) and those with an extra time-like direction are also discussed.

Dzhunushaliev, Vladimir; Folomeev, Vladimir; Minamitsuji, Masato

2010-06-01

429

General properties of the Anisimkin Jr. plate modes.  

PubMed

Acoustic plate modes of different orders n, having equal velocities v(n) close to that of the longitudinal BAW v(L), are numerically studied in crystals of different symmetries. Three families of the modes with v(n) ? v(L), each at relevant plate thickness h/? = (h/?)n, are found (h is the thickness, ? is the wavelength): the generalized Lamb mode with comparable longitudinal u1, shear-horizontal u2, and shear-vertical u3 displacements, the Anisimkin Jr. (AN) mode with u1 > u2 and u3, and u1 ? constant ? 0 at any depth, and the quasilongitudinal (QL) mode with u1 > u2, and u3, but u1 ? constant over the plate thickness. Existence of the families does not depend on anisotropy or piezoelectric properties of the plate, but on the closeness of the mode velocity v(n) to the BAW velocity v(L), the value of the dispersion slope dv(n)/d(h/?) at v(n) = v(L) and h/? = (h/?)n, and the proximity of the plate thickness (h/?)n supporting the mode, to the thickness (h/?)R providing transverse BAW resonance between plate faces. The Lamb modes approach v(n) = v(L) at irregular (h/?)n far from resonance (h/?)R and at large dv(n)/d(h/?) ~10(3) m/s. The two other modes are characterized by lower dispersion dv(n)/d(h/?) ? 10(3) m/s and regular (h/?)n close to the resonance (h/?)R. Because both modes have small vertical displacement on plate faces and propagate almost entirely within the crystals, they are attractive for liquid sensing. PMID:20875992

Anisimkin, Vladimir I

2010-09-01

430

Rapid thickness measurements using guided waves from a scanning laser source.  

PubMed

Guided waves have been effectively used for rapid inspections of plates and pipes. However, the guided-wave technique is not generally used for measuring the remaining thickness in a plate and a pipe due to the difficulties in guided-wave motion. Instead, time-consuming and costly direct contact thickness measurements are still used in practice. This study describes a thickness measurement technique using the A0 mode of a Lamb wave generated by a laser source. A finite element analysis of Lamb wave revealed that this mode propagates with small reflections and mode conversions at a rounded shallow defect and has larger amplitude at thinner regions. Using these characteristics, it is experimentally demonstrated that the distributions of plate thickness were obtained from the amplitude of A0 mode generated by a scanning laser source and received by an angle-beam transducer. The resulting distribution images were obtained at extremely high speed compared to the conventional thickness measurements. PMID:19739722

Hayashi, Takahiro; Murase, Morimasa; Salim, Muhammad Nor

2009-09-01

431

Free flexural vibrations of super elliptic plates  

NASA Astrophysics Data System (ADS)

This paper deals with a direct problem of the free flexural vibrations of a plate with rounded corners on the basis of the theory of thin plates. The plate of uniform thickness is made of linear elastic, isotropic materials, and its periphery is given by a super elliptic function with a power. The super elliptic power defines the shape of the plate ranging from an ellipse to a rectangle and indicates the degree of roundness. The method of solution is based on the method of separation of variables together with certain methods of weighted residuals (i.e., the method of moments, and the Galerkin and least squares methods). The shape functions are chosen in the form of double series polynomials, and they satisfy either a simply supported or a clamped boundary condition. Some numerical results are reported for the vibration frequencies in the case of both symmetric and antisymmetric mode shapes of the plate. The results are compared with the existing literature, and the convergence of solutions is discussed. [Work supported in part by TUBA.

Altekin, Murat; Altay, Gulay; Dokmeci, M. Cengiz

2001-05-01

432

Finite element approximation of free vibration of folded plates  

Microsoft Academic Search

In this paper a finite element approximation of the free vibration of folded plates is studied. Naghdi model, including bending, shear and membrane terms for the plate, is considered. Quadrilateral low order MITC (Mixed Interpolation Tensorial Component) elements are used for the bending and shear effect, coupled with standard quadratic elements enriched with a drilling degree of freedom for the

Erwin Hernández; Luis Hervella-Nieto

2009-01-01

433

Weldability evaluation of high tensile plates using GMAW process  

Microsoft Academic Search

High tensile plates, SAILMA-450 high impact (HI) (yield strength, 45 kg\\/mm2 minimum; ultimate tensile strength, 57 kg\\/mm2 minimum; elongation, 19% minimum; Charpy impact energy 2.0 kg.m at ?20 C minimum) were successfully developed at the Steel\\u000a Authority of India Ltd., up to 32 mm plate thickness. Since then the steel has been extensively used for the fabrication of\\u000a impellers, bridges,

R. Datta; D. Mukerjee; K. L. Rohira; R. Veeraraghavan

1999-01-01

434

Frictional and morphological characteristics of ion plated soft, metallic films  

NASA Technical Reports Server (NTRS)

Ion plated metallic films in contrast to films applied by other deposition techniques offer a lower friction coefficient, longer endurance lives and exhibit a gradual increase in friction coefficient after the film has been worn off. The friction coefficients of metallic films are affected by the degree of adherence, thickness and nucleation and growth characteristics during ion plating lead to a fine, continuous crystalline structure, which contributes to a lower friction coefficient.

Spalvins, T.; Buzek, B.

1981-01-01

435

SUEX process optimization for ultra-thick high-aspect ratio LIGA imaging  

NASA Astrophysics Data System (ADS)

The focus of this paper is on the use of SUEX Thick Dry Film Sheet (TDFS) laminates which DJ DevCorp is developing as a thick resist material in optical and X-ray lithography. Preliminary thick dry film sheets up to 1mm thickness were successfully prepared and patterned at the CAMD X-ray beamlines and presented at HARMST 2007. Recently, new results have been published using SUEX resist sheets in UV lithography showing great market potential including plating molds for metal microparts, polymer MEMS, multilayer microfluidics structures, BioMEMS, medical devices, wafer level packaging processes, and displays. The SUEX TDFS are available in a range of thicknesses from 100?m to 1mm or more and are pre-cut into a number of standard wafer sizes. This new material is a modified epoxy formulation containing an antimony-free photo acid generator (PAG) prepared under a highly controlled solvent-less process which provides uniform coatings between two throw-away layers of protective polyester film. As part of our initial studies resist layers of 250, 500 and 1000?m were laminated onto regular silicon wafers using a hot roll laminator at a speed of 1ft/min at 75°C. The entire substrate preparation takes about 1 hour and with practice users can prepare up to 10 substrates in this time which are typically ready to use within 2 hours. In our efforts to develop a commercially viable product we have conducted experiments using standard equipment available at CAMD (Quintel UV aligner and CAMD XRLM 1 and 4 beamline). Initial X-ray exposure tests were done with a bottom dose ranging between 100 and 400 J/cm3 and a top/bottom dose ratio of less than 3 for sheets up to 2mm in thickness. Exposure time for typical conditions of the CAMD storage ring (ring current ranging between 100 and 160mA, beam lifetime of about 10hrs at 100mA ring current) is about 10-15min for a 4' wafer. After exposure the samples were immediately post exposure baked between 70°C and 110°C using a convection oven, taken out and cooled to RT then relaxed up to 3 days before development to reduce stress. Development was done in PGMEA for up to 3 hours for the 1000?m thick samples followed by a short IPA rinse and drying in air. Very high aspect ratios of 100 or more have been routinely patterned with nearly perfectly straight sidewalls (~1-1.5?m deviation for a 1mm tall structure) and excellent image fidelity.

Johnson, Donald W.; Goettert, Jost; Singh, Varshni; Yemane, Dawit

2011-03-01

436

How many plates?  

NASA Astrophysics Data System (ADS)

Herein I address the current number of plates, the number there should be, and whether there is a pattern in the plate mosaic. Related issues are the optimal sizes and shapes of plates and spacings of ridges, trenches, and transform faults. Similar questions arise in studies of foams, bubble rafts, buckyballs, mudcracks, columnar jointing, the tessellation of spheres, and the planforms of convection. In sphere-covering problems, and in dynamic problems, pentagons replace the familiar hexagons. The “ground” state of plate tectonics on a homogeneous planet may involve ˜12 plates with five nearest and five next-nearest neighbors. The plate mosaic may be a self-organized network of plates and force chains, which are readily reorganized by stress changes. This paper starts with the premise that the mosaic may have simple and surficial explanations rather than convective or plutonic causes. The study of the tessellation of Earth can be called “platonics” to distinguish it from the idea that the lithosphere necessarily mirrors the planform of mantle convection.

Anderson, Don L.

2002-05-01

437

Earthquakes and plate tectonics.  

USGS Publications Warehouse

Earthquakes occur at the following three kinds of plate boundary: ocean ridges where the plates are pulled apart, margins where the plates scrape past one another, and margins where one plate is thrust under the other. Thus, we can predict the general regions on the earth's surface where we can expect large earthquakes in the future. We know that each year about 140 earthquakes of magnitude 6 or greater will occur within this area which is 10% of the earth's surface. But on a worldwide basis we cannot say with much accuracy when these events will occur. The reason is that the processes in plate tectonics have been going on for millions of years. Averaged over this interval, plate motions amount to several mm per year. But at any instant in geologic time, for example the year 1982, we do not know, exactly where we are in the worldwide cycle of strain build-up and strain release. Only by monitoring the stress and strain in small areas, for instance, the San Andreas fault, in great detail can we hope to predict when renewed activity in that part of the plate tectonics arena is likely to take place. -from Author

Spall, H.

1982-01-01

438

Unsteady aerodynamics of fluttering and tumbling plates  

NASA Astrophysics Data System (ADS)

We investigate the aerodynamics of freely falling plates in a quasi-two-dimensional flow at Reynolds number of 10(3) , which is typical for a leaf or business card falling in air. We quantify the trajectories experimentally using high-speed digital video at sufficient resolution to determine the instantaneous plate accelerations and thus to deduce the instantaneous fluid forces. We compare the measurements with direct numerical solutions of the two-dimensional Navier Stokes equation. Using inviscid theory as a guide, we decompose the fluid forces into contributions due to acceleration, translation, and rotation of the plate. For both fluttering and tumbling we find that the fluid circulation is dominated by a rotational term proportional to the angular velocity of the plate, as opposed to the translational velocity for a glider with fixed angle of attack. We find that the torque on a freely falling plate is small, i.e. the torque is one to two orders of magnitude smaller than the torque on a glider with fixed angle of attack. Based on these results we revise the existing ODE models of freely falling plates. We get access to different kinds of dynamics by exploring the phase diagram spanned by the Reynolds number, the dimensionless moment of inertia, and the thickness-to-width ratio. In agreement with previous experiments, we find fluttering, tumbling, and apparently chaotic motion. We further investigate the dependence on initial conditions and find brief transients followed by periodic fluttering described by simple harmonics and tumbling with a pronounced period-two structure. Near the cusp-like turning points, the plates elevate, a feature which would be absent if the lift depended on the translational velocity alone.

Andersen, A.; Pesavento, U.; Wang, Z. Jane

2005-10-01

439

Burma plate motion  

NASA Astrophysics Data System (ADS)

Plate motion in the Indo-Burmese Arc-Andaman-Sumatra region of Burma plate is poorly resolved. This is mainly due to lack of relevant data and complex tectonics of the region. We analyze (1) azimuths of coseismic displacements due to the 2004 Sumatra-Andaman and 2005 Nias earthquakes; (2) estimates of interseismic deformation in the Indo-Burmese Arc, Andaman, Sumatra, and Sagaing Fault regions (all based on GPS measurements); (3) long-term plate motion rates across Sumatra Fault System, Sagaing Fault, and Andaman Sea from geomorphological and other geophysical studies, and (4) the earthquake focal mechanisms in the region. We suggest that the SSW motion of Sunda plate with respect to Indian plate may be partitioned into the dextral strike-slip motion across the Sagaing Fault in the north and Sumatra Fault System in south in the back-arc region, and the arc-normal motion across the Sumatra subduction zone, which becomes oblique in Andaman and southern Indo-Burmese Arc region and dextral in the northern Indo-Burmese Arc region of the fore arc. Under the rigid plate approximation, we estimate a pole for India-Burma plate pair at 27 ± 1°N, 82 ± 1.1°E with an angular velocity of 0.845 ± 0.12°/Ma and for Burma-Sunda at 22.3 ± 1.1°N, 109.3 ± 2.5°E with an angular velocity of 0.67 ± 0.12°/Ma. Thus the plate motion in the northern and southern regions of Burma plate, namely, the Indo-Burmese Arc and Andaman-Sumatra Arc, may be explained by a single pole and does not require a boundary between the two.

Gahalaut, Vineet K.; Gahalaut, Kalpna

2007-10-01

440

Plate Tectonics Jigsaw  

NSDL National Science Digital Library

This activity is a slight variation on an original activity, Discovering Plate Boundaries, developed by Dale Sawyer at Rice University. I made different maps, including more detail in all of the datasets, and used a different map projection, but otherwise the general progression of the activity is the same. More information about jigsaw activities in general can be found in the Jigsaws module. The activity occurs in several sections, which can be completed in one or multiple classes. In the first section, students are divided into "specialist" groups, and each group is given a global map with a single dataset: global seismicity, volcanoes, topography, age of the seafloor, and free-air gravity. Each student is also given a map of plate boundaries. Their task in the specialist group is to become familiar with their dataset and develop categories of plate boundaries based only on their dataset. Each group then presents their results to the class. In the second section, students reorganize into groups with 1-2 of each type of specialist per group. Each new group is given a plate, and they combine their different datasets on that one plate and look for patterns. Again, each plate group presents to the class. The common patterns and connections between the different datasets quickly become apparent, and the final section of the activity involves a short lecture from the instructor about types of plate boundaries and why the common features are generated at those plate boundaries. A follow-up section or class involves using a problem-solving approach to explain the areas that don't "fit" into the typical boundary types - intra-plate volcanism, earthquakes in the Eastern California Shear Zone, etc.

Egger, Anne

441

Improved finite strip Mindlin plate bending element using assumed shear strain distributions  

NASA Technical Reports Server (NTRS)

A linear finite strip plate element based on Mindlin/Reissner plate theory is developed. The analysis is suitable for both thin and thick plates. In the formulation new transverse shear strains are introduced and assumed constant in each two-code linear strip. The element stiffness matrix is explicitly formulated for efficient computation and computer implementation. Numerical results showing the efficiency and predictive capability of the element for the analysis of plates are presented for different support and loading conditions and a wide range of thicknesses. No sign of shear locking phenomenon was observed with the newly developed element.

Chulya, Abhisak; Thompson, Robert L.

1988-01-01

442

Mountains and Moving Plates  

NSDL National Science Digital Library

These are the lecture notes for a class on plate tectonics and mountain building which is taught at the University of Wisconsin-Madison. The course describes the connections between the earth's tectonic plates, earthquakes, and its many mountain ranges. Topics include basic geography, the structure of the earth's interior, the relationships between the seismic cycle, volcanism, and plate movements, erosion of mountains, and mass wasting. Links are provided to additional resources, including aerial photos of geologic features, an interactive map of geology and topography of the United States, and a glossary.

443

Plate Tectonics at Work  

NSDL National Science Digital Library

This is a brief description of the results of plate movement according to the Theory of Plate Tectonics. It explains how divergence at the mid-ocean ridges accounts for the discoveries of Harry Hess. The site also refers to the invention of the magnetometer and the discovery of the young age of the ocean floor basalt. It concludes that these are the kinds of discoveries and thinking that ultimately led to the development of the theory of plate tectonics and that in just a few decades, have greatly changed our view of and notions about our planet and the sciences that attempt to explain its existence and development.

444

Farallon Plate remnants  

NSDL National Science Digital Library

The Rockies are fifteen hundred kilometers, or one thousand miles, to the east. The cause must be the tectonic plate that built these mountains. Its name is Farallon. Farallon started off normally enough. It plunged beneath the North American Plate at a forty-five degree angle. This process sprouted volcanoes to form the Sierra Nevada in what is now California. Next, mantle motions pulled North America westward over Farallon, and the plate scraped along the bottom of the continent - for fifteen hundred kilometers. As North America continued its westward trek, Farallon settled to the bottom of the mantle.

Snodgrass, Stuart; Bunge, Hans-Peter

2002-03-14

445

Buckling of Plates of Inhomogeneous Material with Elasto-Plastic Deformations (Izgib Plastin iz Neodnorodnogo Materials pri Uprugo-Plasticheskikh Deformatsiyakh).  

National Technical Information Service (NTIS)

The elasto-plastic buckling of rectangular plates made of inhomogeneous material when the modulus of elasticity, or shear modulus, and yield point change through the thickness of the plate, is examined. The elastic solutions method in combination with the...

A. I. Strelbitskaya S. I. Matoshko V. A. Kolgadin

1972-01-01

446

Finite Element and Plate Theory Modeling of Acoustic Emission Waveforms  

NASA Technical Reports Server (NTRS)

A comparison was made between two approaches to predict acoustic emission waveforms in thin plates. A normal mode solution method for Mindlin plate theory was used to predict the response of the flexural plate mode to a point source, step-function load, applied on the plate surface. The second approach used a dynamic finite element method to model the problem using equations of motion based on exact linear elasticity. Calculations were made using properties for both isotropic (aluminum) and anisotropic (unidirectional graphite/epoxy composite) materials. For simulations of anisotropic plates, propagation along multiple directions was evaluated. In general, agreement between the two theoretical approaches was good. Discrepancies in the waveforms at longer times were caused by differences in reflections from the lateral plate boundaries. These differences resulted from the fact that the two methods used different boundary conditions. At shorter times in the signals, before reflections, the slight discrepancies in the waveforms were attributed to limitations of Mindlin plate theory, which is an approximate plate theory. The advantages of the finite element method are that it used the exact linear elasticity solutions, and that it can be used to model real source conditions and complicated, finite specimen geometries as well as thick plates. These advantages come at a cost of increased computational difficulty, requiring lengthy calculations on workstations or supercomputers. The Mindlin plate theory solutions, meanwhile, can be quickly generated on personal computers. Specimens with finite geometry can also be modeled. However, only limited simple geometries such as circular or rectangular plates can easily be accommodated with the normal mode solution technique. Likewise, very limited source configurations can be modeled and plate theory is applicable only to thin plates.

Prosser, W. H.; Hamstad, M. A.; Gary, J.; OGallagher, A.

1998-01-01

447

Delaminations in composite plates under transverse impact loads - Experimental results  

NASA Technical Reports Server (NTRS)

Tests were performed measuring the locations and geometries of delaminations in Fiberite T300/976 graphite/epoxy, Fiberite IM7/977-2 graphite-toughened epoxy, and ICI APC-2 graphite/PEEK plates subjected to transverse impact loads. The data provide specific information on the effects of impactor velocity, impactor mass, material, thickness of back ply group, difference in fiber orientation between adjacent ply groups, plate thickness, and impactor nose radius. The data were compared to the results of the Finn-Springer model. The model was found to describe the data with reasonable accuracy.

Finn, Scott R.; He, Ye-Fei; Springer, George S.

1993-01-01

448

Conductivity fuel cell collector plate and method of fabrication  

DOEpatents

An improved method of manufacturing a PEM fuel cell collector plate is disclosed. During molding a highly conductive polymer composite is formed having a relatively high polymer concentration along its external surfaces. After molding the polymer rich layer is removed from the land areas by machining, grinding or similar process. This layer removal results in increased overall conductivity of the molded collector plate. The polymer rich surface remains in the collector plate channels, providing increased mechanical strength and other benefits to the channels. The improved method also permits greater mold cavity thickness providing a number of advantages during the molding process.

Braun, James C. (Juno Beach, FL)

2002-01-01

449

Normal-pressure tests of circular plates with clamped edges  

NASA Technical Reports Server (NTRS)

A fixture is described for making normal-pressure tests of flat plates 5 inches in diameter in which particular care was taken to obtain rigid clamping at the edges. Results are given for 19 plates, ranging in thickness form 0.015 to 0.072 inch. The center deflections and the extreme-fiber stresses at low pressures were found to agree with theoretical values; the center deflections at high pressures were 4 to 12 percent greater than the theoretical values. Empirical curves are derived of the pressure for the beginning of the permanent set as a function of the dimensions of the plate and the tensile properties of the material.

Mcpherson, Albert E; Ramberg, Walter; Levy, Samuel

1942-01-01

450

Influence of cortical bone thickness on the ultrasound velocity  

PubMed Central

Objective An experimental in vitro study was carried out to evaluate the influence of cortical bone thickness on ultrasound propagation velocity. Methods Sixty bone plates were used, made from bovine femurs, with thickness ranging from 1 to 6 mm (10 of each). The ultrasound velocity measurements were performed using a device specially designed for this purpose, in an underwater acoustic tank and with direct contact using contact gel. The transducers were positioned in two ways: on opposite sides, with the bone between them, for the transverse measurement; and parallel to each other, on the same side of the bone plates, for the axial measurements. Results In the axial transmission mode, the ultrasound velocity speed increased with cortical bone thickness, regardless of the distance between the transducers, up to a thickness of 5 mm, then remained constant thereafter. There were no changes in velocity when the transverse measures were made. Conclusion Ultrasound velocity increased with cortical bone thickness in the axial transmission mode, until the thickness surpasses the wavelength, after which point it remained constant. Level of Evidence: Experimental Study.

Mandarano-Filho, Luiz Garcia; Bezuti, Marcio Takey; Mazzer, Nilton; Barbieri, Claudio Henrique

2012-01-01

451

Paleomagnetism and Plate Tectonics.  

National Technical Information Service (NTIS)

Paleomagnetism and plate tectonics are combined in a new procedure for producing paleogeographic reconstructions of the evolution of present day world geography from proto-continents. For each geologic epoch, the continents are first subjected to rotation...

J. Francheteau

1970-01-01

452

Farallon Plate Remnants  

NSDL National Science Digital Library

This image and short video from the NASA's Scientific Visualization Studio shows the remnants of the Farallon Plate based on seismic tomography studies. The studies were conducted by Hans-Peter Bunge at Princeton University in 2000.

Studio, Nasa/goddard S.

453

Feynman's wobbling plate  

NASA Astrophysics Data System (ADS)

In the book Surely You Are Joking, Mr. Feynman! Richard Feynman tells a story of a Cornell cafeteria plate being tossed into the air. As the plate spun, it wobbled. Feynman noticed a relation between the two motions. He solved the motion of the plate by using the Lagrangian approach. This solution didn't satisfy him. He wanted to understand the motion of the plate by analyzing the motion of its individual particles and the forces acting on them. He was successful, but he didn't tell us how he did it. We provide an elementary explanation for the two-to-one ratio of wobble to spin frequencies, based on an analysis of the motion of the particles and the forces acting on them. We also demonstrate the power of numerical simulation and computer animation to provide insight into a physical phenomenon and guidance on how to do the analysis.

Tuleja, Slavomir; Gazovic, Boris; Tomori, Alexander; Hanc, Jozef

2007-03-01

454

Growth Plate Injuries  

MedlinePLUS

... traumatic event, such as a fall or automobile accident, or from chronic stress and overuse. Most growth ... Although many growth plate injuries are caused by accidents that occur during play or athletic activity, growth ...

455

Quarter Wave Plate Program  

NSDL National Science Digital Library

The Quarter Wave Plate program displays the effect of a quarter wave plate on an incident electromagnetic wave. The default electromagnetic wave is plane polarized but this polarization can be changed by specifying the components of the waveâs Jones vector using the input fields. The slider can be used to rotate the quarter wave plate to change its orientation. Quarter Wave Plate is an Open Source Physics program written for the teaching of optics. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the optics_quarterwave.jar file will run the program if Java is installed. Other optics programs are also available. They can be found by searching ComPADRE for Open Source Physics, OSP, or Optics.

Simov, Kiril; Christian, Wolfgang

2008-05-20

456

Half Wave Plate Program  

NSDL National Science Digital Library

The Half Wave Plate program displays the effect of a half wave plate on an incident electromagnetic wave. The default electromagnetic wave is plane polarized but this polarization can be changed by specifying the components of the waveâs Jones vector using the input fields. The slider can be used to rotate the half wave plate to change its orientation. Half Wave Plate is an Open Source Physics program written for the teaching of optics. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the optics_halfwave.jar file will run the program if Java is installed. Other optics programs are also available. They can be found by searching ComPADRE for Open Source Physics, OSP, or Optics.

Simov, Kiril; Christian, Wolfgang

2008-05-20

457

Plate Tectonics Learning Module  

NSDL National Science Digital Library

This plate tectonics unit was designed to be used with a college course in physical geography. Subject matter covered includes: the development of the theory including Wegener's Continental Drift Hypothesis and the existence of Pangaea, Harry Hess and his work on sea-floor spreading, and the final theory. It points out that global features such as deep oceanic trenches, mid-ocean ridges, volcanic activity, and the location of earthquake epicenters can now be related to the story of plate tectonics, since most geological activity occurs along plate boundaries. Divergent, convergent and transform plate boundaries are discussed in detail. This module contains a study guide and outline notes, study questions, and practice quizzes. One feature of the module is a web exploration section with links to twelve outside sites that augment the instruction.

Haberlin, Rita

458

Tectonic Plate Movement.  

ERIC Educational Resources Information Center

Presents an activity that employs movement to enable students to understand concepts related to plate tectonics. Argues that movement brings topics to life in a concrete way and helps children retain knowledge. (DDR)

Landalf, Helen

1998-01-01

459

Flat plate solar oven  

SciTech Connect

The construction of an Indian Rs. 186 (US $20.33) flat-plate solar oven is described. Detailed drawings are provided and relevant information on cooking times and temperature for different foods is given.

Parikh, M.

1981-01-01

460

Wide Rim Microchannel Plates.  

National Technical Information Service (NTIS)

Wide rim 18 mm microchannel plates were successfully manufactured during this contract. The necessary modifications to fixturing and equipment to accomplish the program objectives are detailed in this report. Adjustments to hydrogen firing and vacuum baki...

R. Layman C. Sicora

1977-01-01

461

Interaction between two leaky Lamb wave modes propagating in a water-loaded bilayer consisting of a piezoelectric ceramic plate and a glass plate  

Microsoft Academic Search

The coupling of velocity dispersion curves of leaky Lamb waves is studied based on numerical calculations. The bilayers consisting of two thin plates with various thickness ratios can be regarded equivalently as single-layered plates with various material properties between those of the original two materials in terms of the leaky Lamb wave velocities. The phase velocity dispersion curves, the imaginary

Kenji Motegi; Kohji Toda

1999-01-01

462

A refined nonlinear theory of plates with transverse shear deformation  

NASA Technical Reports Server (NTRS)

A higher-order shear deformation theory of plates accounting for the von Karman strains is presented. The theory contains the same dependent unknowns as in the Hencky-Mindlin type first-order shear deformation theory and accounts for parabolic distribution of the transverse shear strains through the thickness of the plate. Exact solutions of simply supported plates are obtained using the linear theory and the results are compared with the exact solutions of three-dimensional elasticity theory, the first order shear deformation theory, and the classical plate theory. The present theory predicts the deflections, stresses, and frequencies more accurately when compared to the first-order theory and the classical plate theory.

Reddy, J. N.

1984-01-01

463

Stability and vibration of isotropic, orthotropic and laminated plates according to a higher-order shear deformation theory  

Microsoft Academic Search

A higher-order shear deformation theory is used to determine the natural frequencies and buckling loads of elastic plates. The theory accounts for parabolic distribution of the transverse shear strains through the thickness of the plate and rotary inertia. Exact solutions of simply supported plates are obtained and the results are compared with the exact solutions of three-dimensional elasticity theory, the

J. N. Reddy; N. D. Phan

1985-01-01