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1

a Dynamic Model for Thick Elastic Plates  

NASA Astrophysics Data System (ADS)

In this paper the general equations of motion for thick elastic plates with arbitrary shape are derived by using a variational principle. In addition to the influences of the bending, the transverse shear deformation and the rotatory inertia, the proposed theory also contains the effects of the transverse normal stress and the membrane forces. The equations presented in this paper can be reduced to those deduced by E. Reissner and R. D. Mindlin. Some numerical results are compared with those obtained from the Reissner-Mindlin plate theory and the classical plate theory. It is found that for thick plates there exists a dense region of frequencies and the position of frequencies is shifted, so that the influence of the transverse normal stress must be considered.

Deshun, Zeng; Hauger, W.; Matthes, M.; Schreiber, S.

1999-03-01

2

Modes of vibration on sqaure fiberglass epoxy composite thick plate  

NASA Technical Reports Server (NTRS)

The frequencies and nodal patterns of a square thick plate of unidirectional fiberglass epoxy composite are measured experimentally. The constituent material is transversely isotropic. The plate is transversely excited at the center of the upper face, its resonant frequencies in the frequency range of 3 kHz to 21.73 kHz are detected and the measured nodal patterns are sketched.

Williams, J. H., Jr.; Marques, E. R. C.; Lee, S. S.

1986-01-01

3

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

4

Eddy Current Testing of Thick Aluminum Plates with Hidden Cracks  

NASA Astrophysics Data System (ADS)

In this paper we present theoretical analysis which gives the possibility to determine optimum excitation frequencies in eddy current examination of thick aluminum plates. A computer controlled non-destructive testing system and a probe with a magnetoresistive sensor were utilized in laboratory tests. Experiments with specimens containing hidden cracks were carried out for a wide spectrum of frequencies. The optimum operating frequencies achieved from the experiments are in a very good agreement with those obtained by using theoretical analysis. Application of the optimum frequencies makes it possible to detect shallow cracks located on the reverse side of the specimens. Detection of a 15 % crack in a 10 mm thick plate made of aluminum and a 20 % crack in a 20 mm thick plate has been confirmed.

Sikora, R.; Chady, T.; Gratkowski, S.; Komorowski, M.; Stawicki, K.

2003-03-01

5

Thick plate welding with Nd:YAG laser and COIL  

NASA Astrophysics Data System (ADS)

In the field of heavy industries, many products are made of thick metal parts. Nd:YAG laser has been recently developed up to 10 kW. Nd:YAG laser has the characteristics of the optical fiber transmittance and the good absorption by the metal surface, so that it is expected to apply Nd:YAG laser to thick plate welding. This study presents the thick plate welding with Nd:YAG laser and COIL (Chemical Oxygen-Iodine Laser). We have developed a coaxial beam combining system with beams of Nd:YAG laser and COIL. The maximum average power of the combined beam was 19 kW. Welding tests of 304 stainless steel plates were carried out. The effects of various welding parameters were investigated, such as the laser power and pulse modulation. As a result, it was clarified that the pulse wave has good efficiency of deeper penetration as compared to continuous wave at low welding speed. When the combined beam was used, 20 mm penetration depth on the stainless steel could be obtained in high aspect ratio at welding speed of 1m/min. When the combined beams and another Nd:YAG laser beam whose power was 4 kW were used, both side welding on 30 mm thickness plate could be achieved.

Nakabayashi, Tokuhiro; Wani, Fumio; Hayakawa, Akiyoshi; Suzuki, Sachio; Yasuda, Kozo

2003-03-01

6

Growth defects in thick ion-plated coatings  

NASA Technical Reports Server (NTRS)

Industrial ion plating conditions were selected to deposit metallic coatings such as copper, gold, and chromium 2 micrometer thick on metal and glass substrates. The surface finishes of 304 stainless steel, copper, and brass were utilized with mechanically and electrolytically polished surfaces. Nodular growth occurred in these coatings during ion plating as revealed by scanning electron microscopy. Surface irregularities such as scratches, steps, ledges, and so forth are responsible for outward growth, the typical cone type, whereas surface contaminants and loosely settled foreign particles are responsible for lateral growth; namely, the extreme localized surface outgrowths. These defect crystallographic features create porosity in the coatings when subjected to stresses and strains.

Spalvins, T.

1975-01-01

7

Thickness vibrations of a piezoelectric plate with dissipation  

Microsoft Academic Search

The three-dimensional (3-D) equations of linear piezoelectricity with quasi-electrostatic approximation are extended to include losses attributed to the acoustic viscosity and electrical conductivity. These equations are used to investigate effects of dissipation on the propagation of plane waves in an infinite solid and forced thickness vibrations in an infinite piezoelectric plate with general symmetry. For a harmonic plane wave propagating

Peter C. Y. Lee; Ninghui Liu; Arthur Ballato

2004-01-01

8

On the propagation of long thickness-stretch waves in piezoelectric plates.  

PubMed

We study the propagation of thickness-stretch waves in a piezoelectric plate of polarized ceramics with thickness poling or crystals of class 6 mm whose sixfold axis is along the plate thickness. For device applications we consider long waves with wavelengths much longer than the plate thickness. A system of two-dimensional equations in the literature governing thickness-stretch, extensional, and symmetric thickness-shear motions of the plate is further simplified. The equations obtained can be used to analyze piezoelectric plate acoustic wave devices operating with thickness-stretch modes. PMID:24582557

Huang, Dejin; Yang, Jiashi

2014-07-01

9

On two mixed variational principles for thick laminated composite plates  

NASA Astrophysics Data System (ADS)

The basic behavior of the shear deformation plate theories derived from the recently proposed Reissner's and Jing-Liao's functionals is studied in this paper. The difference between these two functionals is on the energy form of transverse normal stress. In Reissner's functional, the transverse normal stress has to be assumed as well as displacements and transverse shear. On the other hand, the independent variables in Jing-Liao's functional include only displacements and transverse shear. The comparison of these functionals is made through two examples, one with assumed transverse normal stress and the other without. It is found that for the cases studied in this paper Jing-Liao's functional provides a simpler, sometimes even better, alternative approach than Reissner's functional in formulating shear deformation theory of thick plates.

Jing, H.-S.; Tzeng, K.-G.

10

The effects of plate thickness and perforation diameter on the supporting vapor velocity for a perforated plate fractionating column  

E-print Network

. Supporting Velocity versus Liquid Iiei'ht by Dif. eront Definitions. 6A. Supporting Velocity versus Perforation ziamoter with Four Inohes of Water on the Plate 27 63. Supportin. Velocity versus Perforation Diameter with o. ' Inches oi' iqater on *he...- tion Diameters oith Two Inches of i'ater or. the Plate?. . . . . . . , 12. Supporting Velocity versus Plate Thickness i' or Licuids of 36 37 Various Surface Tensions. 13. Supporting Velocity versus Plate Thickness for Liquid. s of Page Various...

Cottle, John Ernest

1948-01-01

11

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

12

Plate coating: influence of concentrated surfactants on the film thickness.  

PubMed

We present a large range of experimental data concerning the influence of surfactants on the well-known Landau-Levich-Derjaguin experiment where a liquid film is generated by pulling a plate out of a bath. The thickness h of the film was measured as a function of the pulling velocity V for different kinds of surfactants (C(12)E(6), which is a nonionic surfactant, and DeTAB and DTAB, which are ionic) and at various concentrations near and above the critical micellar concentration (cmc). We report the thickening factor ? = h/h(LLD), where h(LLD) is the film thickness obtained without a surfactant effect, i.e., as for a pure fluid but with the same viscosity and surface tension as the surfactant solution, over a wide range of capillary numbers (Ca = ?V/?, with ? being the surfactant solution viscosity and ? its surface tension) and identify three regimes: (i) at small Ca ? is large due to confinement and surface elasticity (or Marangoni) effects, (ii) for increasing Ca there is an intermediate regime where ? decreases as Ca increases, and (iii) at larger (but still small) Ca ? is slightly higher than unity due to surface viscosity effects. In the case of nonionic surfactants, the second regime begins at a fixed Ca, independent of the surfactant concentration, while for ionic surfactants the transition depends on the concentration, which we suggest is probably due to the existence of an electrostatic barrier to surface adsorption. Control of the physical chemistry at the interface allowed us to elucidate the nature of the three regimes in terms of surface rheological properties. PMID:22283676

Delacotte, Jrme; Montel, Lorraine; Restagno, Frdric; Scheid, Benot; Dollet, Benjamin; Stone, Howard A; Langevin, Dominique; Rio, Emmanuelle

2012-02-28

13

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

14

46 CFR 32.59-1 - Minimum section modulus and plating thickness requirements-TB/ALL.  

Code of Federal Regulations, 2010 CFR

...and plating thickness requirements-TB/ALL. 32.59-1 Section 32.59-1 ...Vessels That Carry Certain Oil Cargoes-TB/ALL 32.59-1 Minimum section modulus and plating thickness requirementsTB/ALL. (a) As used in this section,...

2010-10-01

15

Relationship between clinical periodontal biotype and labial plate thickness: an in vivo study.  

PubMed

The primary aim of this study was to evaluate the differences in labial plate thickness in patients identified as having thin versus thick/average periodontal biotypes. The association between biotype and labial plate thickness was evaluated by correlating information obtained from cone beam computed tomographs, diagnostic impressions, and clinical examinations of the maxillary anterior teeth (canine to canine) in 60 patients. Compared to a thick/average biotype, a thin biotype was associated with thinner labial plate thickness (P < .001), narrower keratinized tissue width (P < .001), greater distance from the cementoenamel junction to the initial alveolar crest (P = .02), and probe visibility through the sulcus. There was no relationship between biotype and tooth height-to-width ratio or facial recession. Periodontal biotype is significantly related to labial plate thickness, alveolar crest position, keratinized tissue width, gingival architecture, and probe visibility but unrelated to facial recession. PMID:21837300

Cook, D Ryan; Mealey, Brian L; Verrett, Ronald G; Mills, Michael P; Noujeim, Marcel E; Lasho, David J; Cronin, Robert J

2011-01-01

16

49 CFR 179.200-6 - Thickness of plates.  

Code of Federal Regulations, 2010 CFR

...joint efficiency; except E =1.0 for seamless heads; L = Main inside radius to which head is dished, measured on concave side in inches; P = Minimum required bursting pressure in psig; S = Minimum tensile strength of plate material...

2010-10-01

17

49 CFR 179.220-6 - Thickness of plates.  

Code of Federal Regulations, 2010 CFR

...joint efficiency; except E =1.0 for seamless heads; L = Main inside radius to which head is dished, measured on concave side in inches; P = Minimum required bursting pressure in psig; S = Minimum tensile strength of plate...

2010-10-01

18

The displacement field in the vibration analysis of laminated thick plates  

SciTech Connect

The present paper discusses the assumption of displacement fields used in the vibration analysis of FRP laminated thick plates. For this purpose, the strain and kinetic energies of a FRP cross-ply laminated plate are evaluated analytically based on the three-dimensional theory of elasticity, and the displacements of the rectangular plate, which are simply-supported at all edges, are expanded into the polynomial forms with respect to thickness coordinate. A frequency equation is formulated by using the energy method minimizing the Lagrange function. In the numerical calculations, natural frequencies are obtained for the plates with various stacking sequence and the thickness ratios, and the validity of the assumption of displacement fields and the range of applicability of the various plate theories (e.g. the Classical Plate Theory (CPT), the First-Order Shear Deformation Theory (FSDT) and the Higher-Order Shear Deformation Theory (HSDT)), which are widely used in the vibration analysis of FRP laminated plates, to the laminated thick plates are discussed by comparing the present results with the CPT and the FSDT solutions.

Ohta, Yoshiki; Narita, Yoshihiro [Hokkaido Inst. of Tech., Hokkaido (Japan). Dept. of Mechanical Engineering

1995-11-01

19

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

Microsoft Academic Search

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

L. F. Qian; R. C. Batra

2005-01-01

20

Laser Based Measurement of Plate Thickness Using a Fundamental Antisymmetric Mode of Lamb Wave  

NASA Astrophysics Data System (ADS)

A guided wave technique for measurement of remaining thickness distribution is presented for the purpose of maintenance of large structures like oil storage tanks and pipe networks. This study used a laser source to excite the guided wave at many locations on aluminum plates with defect that have high ratio of A0 mode transmission and small mode conversions. The A0 mode was used to interrogate the through-thickness over the rastered areas in the test plates. It was expected that many modes of Lamb wave were excited in intact and defect regions of the plates through the thermoelastic stresses from the laser source. The fundamental antisymmetric mode A0 was extracted to indicate the thickness distribution in aluminum test plates with the defect. The results exhibit greater amplitude distributions of A0 mode over thinner regions around defects and smaller amplitudes distributions over the intact regions.

Salim, Muhammad Nor; Hayashi, Takahiro; Murase, Morimasa; Ito, Toshihiro; Kamiya, Shoji

2010-02-01

21

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

22

Governing equations for a piezoelectric plate with graded properties across the thickness  

Microsoft Academic Search

Two-dimensional first-order governing equations for electroded piezoelectric crystal plates with general symmetry and thickness-graded material properties are deduced from the three-dimensional equations of linear piezoelectricity by Mindlin's general procedure of series expansion. Mechanical displacements and thickness-graded material properties, i.e., the elastic stiffnesses, piezoelectric coefficients, dielectric permittivities, and mass density, are expanded in powers of the thickness coordinate, while electric potential

Peter C. Y. Lee; Jiun-Der Yu

1998-01-01

23

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

24

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

25

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

26

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

27

Thick plate bending wave transmission using a mobility power flow approach  

NASA Technical Reports Server (NTRS)

The mobility power flow (MPF) approach is used in this paper to describe the flexural behavior of an L-shaped plate structure consisting of thick plates with rotary inertia and shear deformation effects included in the analysis. The introduction of the thick plate effects significantly increases the complexity of the structural mobility functions used in the definitions of the power flow terms; however, because of the substructuring that is used in the MPF approach, the complexity of the problem is significantly reduced as compared to solving for the global structure. Additionally, with the MPF approach the modal behavior is described. The MPF analysis of the L-shaped plate is performed for the case of point force excitation on one plate, with the two plates being identical in both size and thickness. The results of this analysis are compared to results from the finite-element analysis (FEA) and the statistical energy analysis (SEA) and show very good agreement in the low- and high-frequency regimes, respectively.

Mccollum, M. D.; Cuschieri, J. M.

1990-01-01

28

High-precision thickness setting models for titanium alloy plate cold rolling without tension  

NASA Astrophysics Data System (ADS)

Due to its highly favorable physical and chemical properties, titanium and titanium alloy are widely used in a variety of industries. Because of the low output of a single batch, plate cold rolling without tension is the most common rolling production method for titanium alloy. This method is lack of on-line thickness closed-loop control, with carefully thickness setting models for precision. A set of high-precision thickness setting models are proposed to suit the production method. Because of frequent variations in rolling specification, a model structural for the combination of analytical models and statistical models is adopted to replace the traditional self-learning method. The deformation resistance and friction factor, the primary factors which affect model precision, are considered as the objectives of statistical modeling. Firstly, the coefficient fitting of deformation resistance analytical model based on over-determined equations set is adopted. Additionally, a support vector machine(SVM) is applied to the modeling of the deformation resistance and friction factor. The setting models are applied to a 1450 plate-coiling mill for titanium alloy plate rolling, and then thickness precision is found consistently to be within 3%, exceeding the precision of traditional setting models with a self-learning method based on a large number of stable rolling data. Excellent application performance is obtained. The proposed research provides a set of high-precision thickness setting models which are well adapted to the characteristics of titanium alloy plate cold rolling without tension.

Wang, Xiaochen; Yang, Quan; He, Fei; Sun, Youzhao; Xiao, Huifang

2014-10-01

29

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

30

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

31

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

32

The propagation of Lamb waves in a laminated composite plate with a variable stepped thickness  

Microsoft Academic Search

In this study Lamb waves propagating in a laminated composite plate with stepped thickness variance are characterized through experiments. Understanding the characteristics of Lamb waves is very important for developing a structural health monitoring system, as the number, size, and location of transducers should be determined at the structural design stage. Thin piezoelectric (PZT) transducers bonded to the surface were

Jeongho Han; Chun-Gon Kim; Jung-Yub Kim

2006-01-01

33

Ultrasonic Determination of Temperature Distribution in Thick Plates during Single Sided Heating  

NASA Astrophysics Data System (ADS)

A new ultrasonic method for determining temperature distribution of a thick plate being heated is presented. The principle of the method is based on temperature dependence of ultrasound velocity in heated materials. An inverse analysis method coupled with a finite difference calculation has been developed to determine one-dimensional temperature distribution in the heated plate. To demonstrate the feasibility of the developed method, a single side of a steel plate of 30 mm thickness is heated by contact with molten aluminum at 700C and ultrasonic pulse-echo measurements are then performed for the steel during heating. The transit time of ultrasound of the heated steel is acquired and used to determine the transient variation of temperature distribution of the steel. The ultrasonically determined results almost agree with those measured using thermocouples installed in the steel.

Takahashi, Manabu; Ihara, Ikuo

34

A finite element method including transverse stresses for thick laminated plates and shells  

NASA Astrophysics Data System (ADS)

The work attempts to compute transverse shear and normal stresses in thick laminated composite plates and shells by using shear-deformable finite element formulations. Quasi-3D finite element formulations are conventional displacement formulations which relax the Kirchhoff hypothesis by independently prescribing three displacements and three rotations at each node. Interpolation functions are chosen to obtain the desired spatial variation in the transverse (interlaminar) stresses. A fully 3D solid finite element formulation containing three displacements per node with shear-deformable capability is also developed. It is the objective to extend the described formulations to include thick geometries by layering plate elements through the thickness and integrating the equilibrium equations through the sets of interfacing elements to obtain the transverse normal and shear stresses. Integrating the equilibrium equations to compute interlaminar stresses is performed through several layers of elements by modifying the procedure to account for the continuity between elements provided by the penalty functions. Interlaminar stress results for thick laminates subjected to sinusoidal and cylindrical bending shows the extended plate formulation to be an effective and accurate method for computing interlaminar stresses. Similarly, the integration of the equilibrium equations within the solid formulation improves the interlaminar stresses in thick laminates and near debonds.

Fuehne, Joseph Patrick

35

Active sound radiation control of a thick piezolaminated smart rectangular plate  

NASA Astrophysics Data System (ADS)

A spatial state-space formulation based on the linear three-dimensional piezoelasticity theory in conjunction with the classical Rayleigh integral acoustic radiation model is employed to obtain a semi-analytic solution for the coupled vibroacoustic response of a simply supported, arbitrarily thick, piezolaminated rectangular plate, set in an infinite rigid baffle. The smart structure is composed of an orthotropic supporting core layer integrated with matched volume velocity spatially distributed piezoelectric sensor and uniform force actuator layers. To assist controller design, a frequency-domain subspace-based identification technique is applied to estimate the coupled fluid-structure dynamics of the system. A standard linear quadratic Gaussian (LQG) optimal controller is subsequently synthesized and simulated based on the identified model and the optimal control input voltage for minimizing the estimated net volume velocity (total radiated power) of the panel is calculated in both frequency and time domains. Numerical simulations demonstrate the effectiveness of the adopted volumetric sensing/actuation technique in conjunction with the optimal control strategy for suppressing the predicted sound radiation response of a three-layered (NaNb5O15/Al/PZT4) sandwich panel in both frequency and time domains. The trade-off between dynamic performance and control effort penalty is examined for two different types of loading (i.e., impulsive and broadband random disturbances). Validity of the results is demonstrated by comparison with a commercial finite element package, as well as with the data available in the literature.

Hasheminejad, Seyyed M.; Keshavarzpour, Hemad

2013-09-01

36

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

37

Natural frequencies of thick, symmetrically-laminated, skew, trapezoidal plates with various boundary supports  

SciTech Connect

Increasing use of composite materials in structures requires an accurate method of predicting response. Transverse shear effects can play an important role in laminated structures, even those that are considered thin, and as a result, should not be neglected. The free vibration response of generally laminated, thick, skewed, trapezoidal plates is investigated due of the lack of information in this area. In the method developed, Chebychev polynomials are used as displacement functions in the Rayleigh-Ritz method. To account for various edge supports, free, simply supported, and clamped, appropriate linear and rotational springs are introduced to satisfy the essential boundary conditions. First-order shear theory is used to account for transverse shear effects, and rotary inertia is also included in the model. Convergence of the solution resulting from changes in spring values and number of terms in the series is investigated. To demonstrate the accuracy of the method, results for thin isotropic and laminated plates are compared to past results for various planforms and boundary conditions. Next, thick isotropic plate results are compared to available published results. Thick laminated plate results for various planforms and boundary conditions are then presented. Variations in natural frequencies due to geometric parameter changes, such as taper ratio and sweep angle, are also studied.

Kapania, R.K.; Lovejoy, A.E.

1994-12-31

38

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

39

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 Tukeys 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. PMID:24959508

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

2014-01-01

40

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

41

Finite element analysis of nonlinear thickness-shear vibrations of AT-cut quartz crystal plates  

Microsoft Academic Search

The nonlinear finite element analysis is performed with the nonlinear Mindlin plate theory, which is further simplified to have only the thickness-shear and flexural modes to reduce the complicated couplings due to the consideration of material nonlinearity and higher-order strain components. The 2D nonlinear equations with two variables are implemented so the problem will have a smaller size in comparison

Ji Wang; Leping Chen; Jianke Du; Yuantai Hu; Guoqing Li

2010-01-01

42

Thickness effects on a cracked aluminum plate with composite patch repair  

NASA Astrophysics Data System (ADS)

Post-repair fatigue crack growth was investigated in 3.175, 4.826, and 6.35 mm thick aluminum panels (508 mm long, 153 mm wide), asymmetrically repaired with boron/epoxy composite patches bonded to the plates with FM73 sheet adhesive. Patches were uniaxial with patch to panel stiffness ratios ranging from 0.46 to 1.3. Experimental fatigue tests were carried out at 120 MPa, R = 0.1, and 10 Hz (sinusoidal) to measure patched and unpatched face crack lengths, center crack opening displacements, and selected strains. Crack growth data was acquired using optical, eddy current, and post-test analysis methods. Crack growth rates were calculated using the incremental polynomial method. Test results showed increased plate thickness caused increased fatigue crack growth rates in both unrepaired and repaired panels. Thermally-induced bending due to patch bonding affects crack growth rates. Increased stiffness ratios increased life-spans and reduced crack growth anomalies such as retardation. Disbond growth is more dependent on crack size than on patch configuration and tends to accelerate when the crack grows beyond a critical length or where the patch changes thickness. A three-layer Mindlin plate finite element model was used as a two-dimensional analytical technique to predict patched and unpatched face reaction loads and displacements. This method uses a third plate layer to model the adhesive layer as a continuum. Constraint equations are used to enforce compatibility conditions along the plate-adhesive and adhesive patch interfaces. The calculated loads and displacements, in conjunction with the modified crack closure method, were used to compute stress intensity factors for the crack tips. Crack growth rates were calculated using experimentally determined material constants and the fatigue crack growth relationship (Paris Law) of the unpatched plate. Comparisons of the experimental to analytical curvatures of repaired panels showed excellent agreement for crack lengths up to 60-80 mm long. Enhancements to the predictions are presented to provide accurate life-span predictions. Crack growth rate and life-span predictions are consistent with their experimental counterparts at the unpatched face to within two life-spans. The present analysis is, thus, an effective tool to investigate the behavior of fatigue crack growth in thick and thin aluminum panels repaired with composite patches.

Schubbe, Joel Jon

43

Quantitative Microstructural Characterization of Thick Aluminum Plates Heavily Deformed Using Equal Channel Angular Extrusion  

NASA Astrophysics Data System (ADS)

A detailed quantitative analysis of the microstructure has been performed in three orthogonal planes of 15-mm-thick aluminum plates heavily deformed via two equal channel angular extrusion (ECAE) routes. One route was a conventional route A with no rotation between passes. Another route involved sequential 90 deg rotations about the normal direction (ND) between passes. The microstructure in the center of these plates, and especially the extent of microstructural heterogeneity, has been characterized quantitatively and compared with that in bar samples extruded via either route A or route Bc with 90 deg rotations about the longitudinal axis. Statistically robust data were obtained in this work using gallium enhanced microscopy and EBSD mapping of large sample areas. For the plate processed using route A, the fraction of high-angle boundaries was found to strongly depend on the inspection plane, being smallest in the plane perpendicular to the ND (plane Z), where the largest subgrain size and most profound microstructural heterogeneities were also revealed. In comparison, the plate extruded with 90 deg rotations about the ND was less heterogeneous and contained smaller subgrains in plane Z. Comparing the plate and bar samples, the most refined and least heterogeneous microstructure was observed in the route Bc bar sample. The differences in the microstructure are reflected in the hardness data; the hardness is lowest after ECAE via route A and greatest in the bar sample processed using route Bc.

Mishin, O. V.; Segal, V. M.; Ferrasse, S.

2012-12-01

44

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

45

Coherent structures in the boundary layer of a flat thick plate  

NASA Astrophysics Data System (ADS)

We use POD and EPOD (extended POD) analysis to extract the main features of the flow over a thick flat plate simulated with an LES. Our goal is to better understand the coupling between the velocity field and the surface pressure field. We find that POD modes based on the full velocity and energy fields contain both flapping and shedding frequencies. Pressure modes are found to be uniform in the spanwise direction and the most intense variations take place at the mean reattachment point. Velocity modes educed from the pressure modes with EPOD are seen to correspond to eddies shed by the recirculation bubble. xml:lang="fr"

Podvin, Brengre; Fraigneau, Yann; Tenaud, Christian; Daru, Virginie

2014-06-01

46

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

47

Simulation studies of hadron energy resolution as a function of iron plate thickness at INO-ICAL  

NASA Astrophysics Data System (ADS)

We report on a detailed simulation study of the hadron energy resolution as a function of the thickness of the absorber plates for the proposed Iron Calorimeter (ICAL) detector at the India-based Neutrino Observatory (INO). We compare the hadron resolutions obtained with absorber thicknesses in the range 1.58 cm for neutrino interactions in the energy range 215 GeV, which is relevant to hadron production in atmospheric neutrino interactions. We find that at lower energies, the thickness dependence of energy resolution is steeper than at higher energies, however there is a thickness-independent contribution that dominates at the lower thicknesses discussed in this work. As a result, the gain in hadron energy resolution with decreasing plate thickness is marginal. We present the results in the form of fits to a function with energy-dependent exponent.

Lakshmi, S. M.; Ghosh, A.; Devi, M. M.; Kaur, D.; Choubey, S.; Dighe, A.; Indumathi, D.; Murthy, M. V. N.; Naimuddin, Md

2014-09-01

48

Arctic Crustal Thickness and Oceanic Lithosphere Distribution from Gravity Inversion: Constraining Plate Reconstructions  

NASA Astrophysics Data System (ADS)

Mapping crustal thickness, continental lithosphere thinning and oceanic lithosphere distribution represents a substantial challenge for the Polar Regions. Using gravity anomaly inversion, we have produced the first comprehensive maps of crustal thickness and oceanic lithosphere distribution for the Arctic. The Arctic region formed as a series of small distinct ocean basins leading to a complex distribution of oceanic crust, thinned continental crust, possible micro-continents and rifted continental margins. Mapping of continental lithosphere thinning factor and crustal thickness from gravity inversion provide predictions of ocean-continent transition structure and magmatic type and continent ocean boundary location independent of magnetic isochrons. Restoration of crustal thickness and continent-ocean boundary location from gravity inversion may be used to test plate tectonic reconstructions. Using crustal thickness and continental lithosphere thinning factor maps with superimposed shaded-relief free-air gravity anomaly, we improve the determination of pre-breakup rifted margin conjugacy and sea-floor spreading trajectory within the Arctic basins. By restoring crustal thickness & continental lithosphere thinning maps of the Eurasia Basin & NE Atlantic to their initial post-breakup configuration we show the geometry and segmentation of the rifted continental margins at their time of breakup, together with the location of highly-stretched failed breakup basins and rifted micro-continents. Our gravity inversion predicts thin crust and high continental lithosphere thinning factors in the Makarov, Podvodnikov, Nautilus and Canada Basins consistent with these basins being underlain by oceanic or highly thinned continental crust. Larger crustal thicknesses, in the range 20 - 30 km, are predicted for the Lomonosov, Alpha and Mendeleev Ridges. Moho depths predicted compare well with seismic estimates. Predicted very thin continental or oceanic crust under the North Chuchki Basin has major implications for understanding the plate tectonic history of the Amerasia Basin. Thinned continental crust rather than oceanic crust is predicted under the Laptev Sea. We interpret gravity inversion crustal thicknesses underneath Morris Jessop Rise & Yermak Plateau as continental crust which provided a barrier to the tectonic and palaeo-oceanic linkage between the Arctic & North Atlantic until the Oligocene. Before this time, we link the seafloor spreading within the Eurasia Basin to that in Baffin Bay. We determine Moho depth, crustal basement thickness, continental lithosphere thinning and ocean-continent transition location using a 3D spectral domain gravity inversion method which incorporates a lithosphere thermal gravity anomaly correction. The gravity anomaly contribution from sediments is included in the gravity inversion and assumes a compaction controlled sediment density increase with depth. A correction to the predicted continental lithospheric thinning derived from gravity inversion is made for volcanic material addition produced by decompression melting during continental rifting and seafloor spreading. Gravity anomaly and bathymetry data used in the gravity inversion are from the NGA (U) Arctic Gravity Project and IBCAO respectively; sediment thickness is from a new regional compilation.

Kusznir, N. J.; Alvey, A.; Roberts, A. M.

2013-12-01

49

Analysis of transient heat flow to thick-walled plates and cylinders. [to determine gas heat transfer coefficient  

NASA Technical Reports Server (NTRS)

A methodology is described for the analysis of a transient temperature measurement made in a flat or curved plate subjected to convective heat transfer, such that the surface heat flux, the hot-gas temperture, and the gas heat transfer coefficient can be determined. It is shown that if the transient temperature measurement is made at a particular point located nearly midway in the thickness of the plate there is an important simplification in the data analysis process, in that the factor relating the surface heat flux to the measured rate of rise of temperature becomes invariant for a Fourier Number above 0.60 and for all values of the Biot Number. Parameters are derived, tabulated, and plotted which enable straightforward determination of the surface heat flux, the hot-gas temperature, of the plate, the rate of rise of temperature, the plate thickness and curvature, and the mean thermal properties of the plate material at the test temperature.

Powell, W. B.

1973-01-01

50

Thickness Determination of a Plate with Varying Thickness Using AN Artificial Neural Network for Time-Frequency Representation of Lamb Waves  

NASA Astrophysics Data System (ADS)

Thickness estimation of a varying-thickness media is carried out using an algorithm acting as an artificial neural network for time-frequency representation (TFR) of Lamb waves. Dispersion curves are reconstructed using a self adjustable network multi-input fuzzy rules emulated network (MIFREN). The uncertainty in the time-frequency determination is compared with a typical spectrogram technique. The proposed algorithm is computationally less complex than others used in the past. Experimental results were obtained by exciting Lamb waves on an aluminum plate with varying thickness; these were compared with numerical estimations.

Treesatayapun, C.; Baltazar, A.; Balvantin, A.; Kim, J.-Y.

2009-03-01

51

Interaction of the Fundamental Shear Horizontal Mode with a Through Thickness Crack in an Isotropic Plate  

NASA Astrophysics Data System (ADS)

There is much interest in improving the resolution of ultrasonic guided wave NDE towards defect sizing for applications where access is difficult. This paper presents a study of the interaction of the cylindrical crested fundamental shear horizontal (SH0) mode with a through thickness crack in an isotropic plate. The study examines the reflection and diffraction of the wave at the crack, in order to gain understanding for the development of imaging procedures. Circular wavefronts are used to imitate the field from individual elements of a transducer array, which behave as point sources. Finite element (FE) simulations are used to gain an insight into the problem and the relative strengths of the diffraction and reflection fields for various crack lengths are assessed.

Rajagopal, P.; Lowe, M. J. S.

2006-03-01

52

Optimal rectangular plate and shallow shell topologies using thickness distribution or homogenization  

NASA Astrophysics Data System (ADS)

Topological optimization of plates, as well as shallow cylindrical and curved (spherical) shells, are attempted in the present study. For all structures examined, our objective is the minimization of the strain energy function under a volume constraint. An optimum distribution of thickness or microstructural density is sought under the hypothesis that the design variables can only be assigned their extreme allowable bounds, or values very near them, so that material can be removed from low density areas and thus, an optimum topology can be determined. The structural response is computed via a finite element analysis. The analytical formulation is based on a form of linear shallow shell theory with the effects of transverse shear deformation and bending-extensional coupling included. The method of feasible directions is used to perform the optimization task. Numerical examples for various boundary conditions showing similarities or differences of the two methods are presented and discussed. For all structures examined, it is found that the assumption of a repetitious microstructure based on homogenization theory resulted in stronger optima. For clamped plates and shells, both methods converged to nearly identical topologies, an indication of possible global optimal layouts.

Tenek, Lazarus H.; Hagiwara, Ichiro

1994-05-01

53

A {1,2}-Order Plate Theory Accounting for Three-Dimensional Thermoelastic Deformations in Thick Composite and Sandwich Laminates  

NASA Technical Reports Server (NTRS)

A {1,2}-order theory for laminated composite and sandwich plates is extended to include thermoelastic effects. The theory incorporates all three-dimensional strains and stresses. Mixed-field assumptions are introduced which include linear in-plane displacements, parabolic transverse displacement and shear strains, and a cubic distribution of the transverse normal stress. Least squares strain compatibility conditions and exact traction boundary conditions are enforced to yield higher polynomial degree distributions for the transverse shear strains and transverse normal stress through the plate thickness. The principle of virtual work is used to derive a 10th-order system of equilibrium equations and associated Poisson boundary conditions. The predictive capability of the theory is demonstrated using a closed-form analytic solution for a simply-supported rectangular plate subjected to a linearly varying temperature field across the thickness. Several thin and moderately thick laminated composite and sandwich plates are analyzed. Numerical comparisons are made with corresponding solutions of the first-order shear deformation theory and three-dimensional elasticity theory. These results, which closely approximate the three-dimensional elasticity solutions, demonstrate that through - the - thickness deformations even in relatively thin and, especially in thick. composite and sandwich laminates can be significant under severe thermal gradients. The {1,2}-order kinematic assumptions insure an overall accurate theory that is in general superior and, in some cases, equivalent to the first-order theory.

Tessler, A.; Annett, M. S.; Gendron, G.

2001-01-01

54

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

55

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

56

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

57

Earthquakes, Plate Boundaries, and Depth Indiana Standard Indicators  

E-print Network

, volcanoes, trenches, and mountains. ES.1.24 ­ Understand and discuss continental drift, sea-floor spreading of the ocean and continental crust and the depth of earthquakes, and types of plate boundaries where or continental crust? · What is the explanation behind the earthquakes that do not occur at plate boundaries? #12

Polly, David

58

Homogenization of thick periodic plates: application of the Bending-Gradient plate theory to a folded core sandwich panel  

E-print Network

theory, Higher-order Models, Sandwich panels, Homogenization, Periodic plates, Folded cores, Chevron-Gradient homogenization scheme and apply it to a sandwich panel including the chevron pattern. It turns out that the shear to a broad variety of configurations. The present work is dedicated to the chevron pattern (Figure A.1) which

Paris-Sud XI, Université de

59

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

60

Multiregional evaluation of the SimPlate heterotrophic plate count method compared to the standard plate count agar pour plate method in water.  

PubMed

A new SimPlate heterotrophic plate count (HPC) method (IDEXX Laboratories, Westbrook, Maine) was compared with the pour plate method at 35 degrees C for 48 h. Six laboratories tested a total of 632 water samples. The SimPlate HPC method was found to be equivalent to the pour plate method by regression analysis (r = 0. 95; y = 0.99X + 0.06). PMID:10618266

Jackson, R W; Osborne, K; Barnes, G; Jolliff, C; Zamani, D; Roll, B; Stillings, A; Herzog, D; Cannon, S; Loveland, S

2000-01-01

61

Multiregional Evaluation of the SimPlate Heterotrophic Plate Count Method Compared to the Standard Plate Count Agar Pour Plate Method in Water  

PubMed Central

A new SimPlate heterotrophic plate count (HPC) method (IDEXX Laboratories, Westbrook, Maine) was compared with the pour plate method at 35C for 48 h. Six laboratories tested a total of 632 water samples. The SimPlate HPC method was found to be equivalent to the pour plate method by regression analysis (r = 0.95; y = 0.99X + 0.06). PMID:10618266

Jackson, R. Wayne; Osborne, Karen; Barnes, Gary; Jolliff, Carol; Zamani, Dianna; Roll, Bruce; Stillings, Amy; Herzog, David; Cannon, Shelly; Loveland, Scott

2000-01-01

62

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

63

Magnitude and phase spectral analysis of through-transmitted ultrasound pulses for the determination of the ultrasound velocity and the thickness of solid plates  

NASA Astrophysics Data System (ADS)

A method that combines transmission of air-coupled ultrasound pulses through solid plates and magnitude and phase spectral analysis is presented. The purpose is to determine, simultaneously, velocity and attenuation coefficient of the ultrasounds in the material, and the thickness and the density of the plate. This is especially useful when thickness can not be measured independently and it is necessary to obtain estimations for the velocity and the attenuation coefficient of ultrasounds in the plate.

Gmez lvarez-Arenas, Toms E.

2010-01-01

64

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

65

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

SciTech Connect

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 [Research Institute of Industrial Science and Technology, 32 Hyoja-Dong, Nam-Ku, Pohang (Korea, Republic of); Park, Ik-Keun; Kim, Tae-Hyung [Dept. of Mechanical Engineering, Seoul National University of Technology, Seoul 139-743 (Korea, Republic of); Kim, Hyun-Mook [Graduate School, Hanyang University, Seoul 133-791 (Korea, Republic of); Kim, Yong-Kwon [Graduate School of Energy and Environment, Seoul National University of Technology, Seoul 139-743 (Korea, Republic of); Cho, Yong-Sang [Korea Electric Power Research Institute, Daejeon 305-380 (Korea, Republic of)

2006-03-06

66

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

SciTech Connect

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 [Shanghai Key Laboratory of Digital Manufacture for Thin-walled Structures, Shanghai Jiao Tong University, Shanghai 200240 (China); Yang, Bing; Gao, Yongsheng [Automotive Steel Research Institute, R and D Center, BaoShan Iron and Steel Co.,Ltd, Shanghai 201900 (China)

2013-12-16

67

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

68

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

69

The dynamic mechanical properties study on the sandwich panel of different thickness steel plate-foam aluminum core  

NASA Astrophysics Data System (ADS)

The foam aluminum belongs to multi-cell materials, and it has good mechanical performance, such as large deformation capacity and good energy absorption, and usually used as core material of sandwich panel, now it is widely used in automotive, aviation, aerospace and other fields, particularly suitable for various anti-collision structure and buffer structure. In this article, based on an engineering background, the INSTRON4505 electronic universal testing machine and split Hopkinson pressure bar (SHPB) were used for testing the static and dynamic mechanical properties of sandwich panel with different thickness steel plate- foam aluminum core, from the results we can see that the steel plate thickness has big influence on the stress-strain curve of the sandwich panel, and also takes the sandwich panel with 1mm steel panel to study the material strain rate dependence which under different high shock wave stress loaded, the results show that the sandwich panel is strain rate dependence material. And also, in order to get good waveforms in the SHPB experiment, the waveform shaped technique is used in the dynamic experiments, and the study of this paper will good to sandwich panel used in the engineering.

Chang, Zhongliang; Zou, Guangping; Zhao, Weiling; Xia, Peixiu

2010-03-01

70

The dynamic mechanical properties study on the sandwich panel of different thickness steel plate-foam aluminum core  

NASA Astrophysics Data System (ADS)

The foam aluminum belongs to multi-cell materials, and it has good mechanical performance, such as large deformation capacity and good energy absorption, and usually used as core material of sandwich panel, now it is widely used in automotive, aviation, aerospace and other fields, particularly suitable for various anti-collision structure and buffer structure. In this article, based on an engineering background, the INSTRON4505 electronic universal testing machine and split Hopkinson pressure bar (SHPB) were used for testing the static and dynamic mechanical properties of sandwich panel with different thickness steel plate- foam aluminum core, from the results we can see that the steel plate thickness has big influence on the stress-strain curve of the sandwich panel, and also takes the sandwich panel with 1mm steel panel to study the material strain rate dependence which under different high shock wave stress loaded, the results show that the sandwich panel is strain rate dependence material. And also, in order to get good waveforms in the SHPB experiment, the waveform shaped technique is used in the dynamic experiments, and the study of this paper will good to sandwich panel used in the engineering.

Chang, Zhongliang; Zou, Guangping; Zhao, Weiling; Xia, Peixiu

2009-12-01

71

Open-ended rectangular waveguide for nondestructive thickness measurement and variation detection of lossy dielectric slabs backed by a conducting plate  

Microsoft Academic Search

Solutions for fields inside a slab of a generally lossy dielectric medium backed by a conducting plate, placed outside a waveguide-fed rectangular aperture, are used for the microwave nondestructive thickness measurement of such dielectric slabs. Upon construction of the waveguide terminating admittance expression from its variational form, an inverse problem is solved to extract the slab thickness form the conductance

Sasan Bakhtiari; Stoyan I. Ganchev; Reza Zoughi

1993-01-01

72

Parameterization of hybrid laser-assisted oxygen cutting of thick steel plates  

NASA Astrophysics Data System (ADS)

Specific features of hybrid laser-assisted oxygen cutting of mild steel sheets are studied theoretically and experimentally. The shape and geometrical size of a supersonic confuser-diffuser nozzle are demonstrated to play an important role in the formation of oxygen cutting jet. The numerical solution of three-dimensional Navier-Stokes equations reveals a pseudoshock phenomenon in the gas flow in a narrow channel, which is the reason for elevated roughness in the lower part of the cut under certain conditions. A method of the analytical calculation of effective cutting parameters, which depend on the material thickness, nozzle geometry, and range of oxygen pressure, is proposed. Engineering recommendations are formulated, which are used to perform full-scale experiments on an automated laser technological complex in cutting steel sheets upto 30-50 mm thick.

Ermolaev, G. V.; Kovalev, O. B.; Zaitsev, A. V.

2013-04-01

73

Transmission analysis of ultrasonic Lamb mode conversion in a plate with partial-thickness notch.  

PubMed

Mode conversions of Lamb waves can occur upon encountering damage or defect such as a notch, leading to newly-converted modes apart from wave reflection and transmission. In this paper, the transmission of the fundamental Lamb modes symmetrical S0 and anti-symmetrical A0 with anti-symmetrical notches were investigated in steel plates within the relatively short propagation distance. The group velocity and modal energy of the converted modes were analyzed using simulations and experiments. Two-dimensional finite difference time domain (2D-FDTD) method was employed to calculate the scattering field and extract numerical trends for simulation study and experimental confirmation. Both simulations and experiments revealed that the apparent group velocities of the converted modes in the transmitted signals subject to the notch positions. To describe the mode conversion degree and evaluate the notch severity, wave packets of the originally-transmitted modes and newly-converted modes were separated and corresponding mode energy percentages were analyzed at different notch severities. Frequency-sweeping measurements illustrated that the modal energy percentages varied monotonically over the notch-depth increase with a statistically consistency (R=1.00, P<0.0004). PMID:23916666

Xu, Kailiang; Ta, Dean; Su, Zhongqing; Wang, Weiqi

2014-01-01

74

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

75

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

76

Simultaneous measurement of surface shape and variation in optical thickness of a transparent parallel plate in wavelength-scanning Fizeau interferometer.  

PubMed

Wavelength-scanning interferometry permits the simultaneous measurement of variations in surface shape and optical thickness of a nearly parallel plate. Interference signals from both surfaces of the test plate can be separated in frequency space; however, these frequencies are shifted from the expected frequency by the refractive-index dispersion of the test plate and any nonlinearity that is due to wavelength scanning. Conventional Fourier analysis is sensitive to this detuning of the signal frequency and suffers from multiple-beam interference noise. We propose new wavelength-scanning algorithms that permit a large tolerance for dispersion of the test plate and nonlinearity of scanning. Two 19-sample algorithms that suppress multiple-interference noise up to the second order of the reflectance of the test plate are presented. Experimental results show that the variation in surface shape and optical thickness of a glass parallel plate of 250-mm diameter was measured with a resolution of 1-2 nm rms. PMID:15008525

Hibino, Kenichi; Oreb, Bozenko F; Fairman, Philip S; Burke, Jan

2004-02-20

77

A study of narrow gap laser welding for thick plates using the multi-layer and multi-pass method  

NASA Astrophysics Data System (ADS)

This paper details a new method that combines laser autogenous welding, laser wire filling welding and hybrid laser-GMAW welding to weld 30 mm thick plate using a multi-layer, multi-pass process. A Y shaped groove was used to create the joint. Research was also performed to optimize the groove size and the processing parameters. Laser autogenous welding is first used to create the backing weld. The lower, narrowest part of the groove is then welded using laser wire filling welding. Finally, the upper part of the groove is welded using laser-GMAW hybrid welding. Additionally, the wire feeding and droplet transfer behaviors are observed by high speed photography. The two main conclusions from this work are: the wire is often biased towards the side walls, resulting in a lack of fusion at the joint and the creation of other defects for larger groove sizes. Additionally, this results in the droplet transfer behavior becoming unstable, leading to a poor weld appearance for smaller groove sizes.

Li, Ruoyang; Wang, Tianjiao; Wang, Chunming; Yan, Fei; Shao, Xinyu; Hu, Xiyuan; Li, Jianmin

2014-12-01

78

Preparation and evaluation of submerged-arc weld in 4 inch thick 3Cr-1. 5Mo-0. 1V steel plate. Final report  

SciTech Connect

A 79-pass submerged-arc weld joint was prepared in a 4-inch thick 3Cr-1.5Mo-0.1V steel plate using welding wire with a composition similar to the base plate. Welding was made without difficulty, and no cracking was observed after stress relieving at 1175 F (635 C) for 4 hours. After stress relieving to tensile strength levels of 80 to 110 ksi (550 to 760 Mpa), tensile and Charpy impact properties of the weld metal and the heat-affected zone (HAZ) were determined. The HAZ exhibited virtually the same tensile strength and toughness as the base plate. The weld metal exhibited somewhat lower toughness, while its tensile strength was equivalent to that of the base plate.

Wada, T.; Cox, T.B.

1983-12-15

79

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

PubMed

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 5.6 kg of filter-collected combustion particulate matter (SRM 2975) from operating forklifts with diesel engines. The mutagenicity and a summary of the related chemical analysis of mutagens in SRM 1975 is presented in this paper, and are available from the NIST. Mutagenicity test conditions were: Salmonella typhimurium TA98, TA100 (standard strains); TA98NR, TA100NR (nitroreductase (NR) gene deficient); and YG1021 and YG1026 (NR gene addition); 10 dose levels in the linear portion of the dose-response curve; duplicate plates per dose; and S9 at 6.4% or 1.1 mg of protein/plate. Four rounds of testing were conducted. Rounds were conducted at least 1 week apart. Slopes (revertants/microg) were calculated by the linear regression rejection model of Bernstein and by the Stead and Krewski models which analyze non-linear data. The GeneTox Manager software package developed at the EPA was used to record the data and calculate the slopes. Results demonstrated: (1) the ranking of slopes without S9 was: YG1021 > TA98 > TA98NR > YG1026 > TA100 > TA100NR in all three statistical models; (2) the mutagenic activity of SRM 1975 was significantly increased by the presence of the NR gene; (3) the slope values for the TA100 series were significantly less than for the TA98 series; (4) in general, the addition of the S9 significantly reduced mutagenic activity; (5) the mutagenic activity of the SRM 1975 was stable over time and variability was low (generally less than 20% in slope values over the 4 rounds); and (6) agreement of the slope values among the three models was excellent due to the linear nature of the data. These data will be useful in ranking other diesel and air samples for mutagenic activity, for quality assurance of data generated in different laboratories, for quality control within a laboratory, and as positive control values for future air and automotive emission studies. PMID:9268049

Hughes, T J; Lewtas, J; Claxton, L D

1997-07-14

80

76 FR 35806 - Amendments to National Emission Standards for Hazardous Air Pollutants for Area Sources: Plating...  

Federal Register 2010, 2011, 2012, 2013

...for Hazardous Air Pollutants for Area Sources: Plating and Polishing AGENCY: Environmental...HAP) for the plating and polishing area source category under section 112 of the Clean...NESHAP) for the plating and polishing area source category published on June 12,...

2011-06-20

81

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

82

Fluids Mechanics -1 Consider a circular plate of outer radius Ro (a portion of which is shown in the figure). A fluid filled gap of thickness h(t)  

E-print Network

Fluids Mechanics - 1 Consider a circular plate of outer radius Ro (a portion of which is shown in the figure). A fluid filled gap of thickness h(t) exists between the bottom of the plate and the flat surface that the fluid filling the gap is incompressible, inviscid and its motion is irrotational. Also assume the radial

Virginia Tech

83

The effect of material type and plate thickness on drilling time of abrasive water jet drilling process  

Microsoft Academic Search

Abrasive water jet processing is being developed in relation to the developments in engineering materials science. In this study, brass-353 (?+? brass), 99% pure aluminum, Al-6061 aluminum alloy, AISI 304, AISI 1030 and cold working tool steel (D3) materials were drilled with AWJ. The effects of thickness and material type on the drilling time were investigated and discussed. Hardness of

Adnan Akkurt

2009-01-01

84

Standard guide for mutual inductance bridge applications for wall thickness determinations in boiler tubing  

E-print Network

1.1 This guide describes a procedure for obtaining relative wall thickness indications in ferromagnetic and non-ferromagnetic steels using the mutual inductance bridge method. The procedure is intended for use with instruments capable of inducing two substantially identical magnetic fields and noting the change in inductance resulting from differing amounts of steel. It is used to distinguish acceptable wall thickness conditions from those which could place tubular vessels or piping at risk of bursting under high temperature and pressure conditions. 1.2 This guide is intended to satisfy two general needs for users of industrial Mutual Inductance Bridge (MIB) equipment: (1) the need for a tutorial guide addressing the general principles of Mutual Inductance Bridges as they apply to industrial piping; and (2) the need for a consistent set of MIB performance parameter definitions, including how these performance parameters relate to MIB system specifications. Potential users and buyers, as well as experienced M...

American Society for Testing and Materials. Philadelphia

2010-01-01

85

Influence of Laser Wavelength on Melt Bath Dynamics and Resulting Seam Quality at Welding of Thick Plates  

NASA Astrophysics Data System (ADS)

CO2- and solid-state lasers are the most widely used beam sources. Owing to their different physical beam characteristics, these two types of laser differ fundamentally not only in how the beam is guided but also in their process behavior during deep penetration welding. Almost all industrial applications in thick material > 8 mm have to be full penetration welds to increase fatigue strength, for example in ship building, pipeline construction, train and rail construction or power-train, Holzer et al., 2011. Therefore process behavior and limits at full penetration will be analyzed in detail for both beam sources.

Haug, P.; Rominger, V.; Speker, N.; Weber, R.; Graf, T.; Weigl, M.; Schmidt, M.

86

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

87

Within-plate magmatism under condition of abnormally thick sialic crust: Evidence for Proterozoic anorthosite-rapakivi granite complexes of the East-European Craton  

NASA Astrophysics Data System (ADS)

Mid-Proterozoic (1.8-1.5 Ga) large bimodal multistage anorthosite-rapakivi granite complexes (ARGCs) are distinct magmatic assemblages in central part of the East European Craton. ARGCs formation commenced after stabilization of the Svecofennian orogen and relics of its abnormally thick (up to 50-60 km now) crust survived here in many places. Such massifs are practically absent at the eastern part of the craton (Kola-Karelian, Volga-Urals, etc. domains) with normal thickness (~40 km) of the crust. The ARGCs formation was accompanied by emplacement of diabase, quartz porphyry and complex dike swarms. Intra-plutonic diabase dikes (Fe-Ti basalts plume-related type), intruding the rapakivi granites, are often crossed in turn by later portions of granites; injections of basaltic melt into granitic magma chambers resulted in magma mingling. It indicates that melted out occurred simultaneously in mantle and crust during ARGC formation. Geochemical peculiarities of the ARGC rocks are enrichment in alkali (especially in K), Ti, Zn, Pb, and Zr, relatively high concentrations of Be, Sn, In, Y, Nb, Rb, F, Cu, W and Mo, and sometimes - Li and U. ?Nd value, ranges from -1.2 to +1.6, and relative high Th and Zn contents, most frequently observable in anorthosites, imply that the mafic magmas were considerably contaminated by crustal components. According to geophysical data, ARGCs represent upper parts of large transcrustal systems, composed by alternation of basic and silicic rocks, which located above rises of the mantle up to 10-20 km high. Such localization of ARGCs, probably evidence that such protuberances were mantle plume heads in time, where melting of their material occurred due to adiabatic decompression. Newly-formed basaltic melts (apparently Fe-Ti basalts, similar in composition to intra-plutonic dike rocks) intruded at different depths into abnormally thick sialic crust of stabilized by then Svecofennian orogen in form of large sills and caused melting of crustal material above them. As a result, complex magmatic systems appeared here. Partial melting of the crust was the consequence of advective heating from the hot mantle magmas. Due to convection, the main heat loss during solidification was realized through roofs of basaltic sills. Consequently, extensive melting of warmed-up siliceous rocks above them would be occurred, at that thickness of newly formed granitic layer could twice exceed the thickness of basaltic sill (Huppert and Sparks, 1988). During the initial stages relatively cool crustal material at the boundary of basaltic melt and sialic roof involved in convective flows and dissolved in hot basaltic melt, which led to it's enrichment in SiO2 and Al2O3., led to predomination of plagioclase cumulates among the rocks of basic sections. Solidification of such complex chambers were began from hardening of lower basic layers; it led to domination of ascending currents in the upper silicic layer, which was favour to appearance of specific rapakivi textures in granites. ARGCs are usually associated with large Mid-Proterozoic belts of within-plate felsic volcanism, developed on all Precambrian shields on place of stabilized Paleoproterozoic orogens with thick sialic crust. From such point of view, it was the main reason for existence of such volcanism, because majority of mantle-derived mafic magmas was not reached the surface and secondary felsic melts were predominated. Evidently, ARGCs illustrate structure and processes in transitions magma chambers of such peculiar magmatic systems. Many investigators suggest that ARGCs are a part of anorthosite-mangerite-charnockite granite (AMCG) suite. However, typical AMCG complexes were commonly developed in mobile zones and undergone by deformation and high-grade metamorphism. In contrast, anorogenic ARGCs are usually localized among stabilized domains and appeared on places where Paleoproterozoic orogens completed their development. So, their tectonic settings can be described in terms of within-plate activity, distinctive from the settings of the AMCG suite.

Sharkov, Evgenii

2010-05-01

88

[Quantitative trait locus analysis of standard length, body depth and body thickness in mirror carp (Cyprinus carpio L.)].  

PubMed

Based on a full-sib family, the genetic linkage map was constructed with 246 microsatellite and 306 SNP markers, which was used to detect the QTLs for standard length (SL), body depth (H), body thickness (BT), and the ratio of standard length and body depth (SLH) in mirror carp by GridQTL software. The results indicated that a total of 14 related QTLs distributed on the 7 linkage groups were obtained. Seven QTLs were related to standard length, of which the linkage groups of LG6, LG17, LG21, LG23, and LG35 were at 5% significant level, and linkage group LG1 and LG28 were at 1% significant level, which explained 6.6%-12.6% of the phenotypic variance. Three QTLs were identified for body depth on the linkage groups of LG17, LG23 and LG28 (P amp; 0.01), accounting for 11.6%, 12.7%, and 15.6% of the phenotypic variance, respectively. Two QTLs were associated with body thickness on the linkage of LG23 and LG28 (P amp; 0.05), which explained 8.6% and 7.2% of the phenotypic variation, respectively. Two QTLs were responsible for the ratio of standard length and body depth on the linkage of LG21 and LG35 (P amp; 0.05), both of which explained 8.2% of the phenotypic variance. The results provide a useful reference for further candidate gene research and molecular marker assisted selection in mirror carp. PMID:22207383

Zheng, Xian-Hu; Kuang, You-Yi; Lu, Cui-Yun; Wang, Xuan-Peng; Li, Wen-Sheng; L, Wei-Hua; Sun, Xiao-Wen

2011-12-01

89

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 525.9034.08 m, 525.9234.10 m, 530.3035.62 m, and 543.5037.11 m 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 -0.056.77 m (13.3/-13.3) between SD-OCT and Scheimpflug-Placido topographer, 4.383.79 m (11.8/-3.1) between OLCR and SD-OCT, 4.386.03 m (16.2/-7.5) between OLCR and Scheimpflug-Placido topographer, 13.206.46 m (25.9/0.5) between USP and OLCR, 17.596.76 m (30.8/4.3) between USP and SD-OCT, and 17.588.13 m (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. PMID:24790874

Bayhan, Hasan Ali; Aslan Bayhan, Seray; Can, ?zzet

2014-01-01

90

Angular shear plate  

Microsoft Academic Search

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

Mitchell C. Ruda; Alan W. Greynolds; Tilman W. Stuhlinger

2009-01-01

91

Plate Tectonics  

NSDL National Science Digital Library

The Plate Tectonics SciPack explores the various materials that make up Earth and the processes they undergo to provide a framework for understanding how continents are created and change over time. The focus is on Standards and Benchmarks related to Earth's layers, oceanic and continental plates and the interactions between plates.In addition to comprehensive inquiry-based learning materials tied to Science Education Standards and Benchmarks, the SciPack includes the following additional components:� Pedagogical Implications section addressing common misconceptions, teaching resources and strand maps linking grade band appropriate content to standards. � Access to one-on-one support via e-mail to content "Wizards".� Final Assessment which can be used to certify mastery of the concepts.Learning Outcomes:Plate Tectonics: Layered Earth� Identify that Earth has layers (not necessarily name them), and that the interior is hotter and more dense than the crust.� Identify the crust as mechanically strong, and the underlying mantle as deformable and convecting.Plate Tectonics: Plates� Identify that the outermost layer of Earth is made up of separate plates.� Choose the correct speed of the motion of plates.� Identify the ocean floor as plate, in addition to the continents (to combat the common idea that only continents are plates, floating around on the oceans).� Recognize that oceans and continents can coexist on the same plate.Plate Tectonics: Plate Interactions� Identify the different interactions between plates.� Discuss what happens as a result of those interactions.Plate Tectonics: Consequences of Plate Interactions� 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.Plate Tectonics: Lines of Evidence� Use plate tectonics to explain changes in continents and their positions over geologic time.� Provide evidence for the idea of plates, including the location of earthquakes and volcanoes, continental drift, magnetic orientation of rocks in the ocean floor, etc.

National Science Teachers Association (NSTA)

2007-03-21

92

Standard Test Method for Mechanical Hydrogen Embrittlement Evaluation of Plating/Coating Processes and Service Environments  

E-print Network

1.1 This test method describes mechanical test methods and defines acceptance criteria for coating and plating processes that can cause hydrogen embrittlement in steels. Subsequent exposure to chemicals encountered in service environments, such as fluids, cleaning treatments or maintenance chemicals that come in contact with the plated/coated or bare surface of the steel, can also be evaluated. 1.2 This test method is not intended to measure the relative susceptibility of different steels. The relative susceptibility of different materials to hydrogen embrittlement may be determined in accordance with Test Method F1459 and Test Method F1624. 1.3 This test method specifies the use of air melted AISI E4340 steel per SAE AMS-S-5000 (formerly MIL-S-5000) heat treated to 260 280 ksi (pounds per square inch x 1000) as the baseline. This combination of alloy and heat treat level has been used for many years and a large database has been accumulated in the aerospace industry on its specific response to exposure...

American Society for Testing and Materials. Philadelphia

2010-01-01

93

Angular shear plate  

SciTech Connect

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

94

Chromium ion plating studies for enhancement of bearing lifetime  

NASA Technical Reports Server (NTRS)

Six 440-C hardened stainless steel roller bearing test rods were ion plated with various chromium films of thicknesses from .2 microns to 7 microns. The thinner (approximately .2 microns) coating sample had 3 times the fatigue life of the unplated (standard) specimens. Contrastingly, the samples having thicker coatings (several microns) had short fatigue lives (about 3% of the unplated standard).

Davis, J. H.

1982-01-01

95

Assessment of computational models for thermoelectroelastic multilayered plates  

NASA Technical Reports Server (NTRS)

A study is made of the accuracy of the steady-state (static) thermoelectroelastic response of multilayered hybrid composite plates predicted by five modeling approaches, based on two-dimensional plate theories. The plates consist of a combination of fiber-reinforced and piezothermoelastic layers. The standard of comparison is taken to be the exact three-dimensional thermoelectroelastic solutions, and the quantities compared include gross response characteristics (e.g., strain energy components, and average through-the-thickness displacements); detailed, through-the-thickness distributions of displacements and stresses; and sensitivity coefficients of the response quantities (derivatives of the response quantities with respect to material parameters of the plate). The modeling approaches considered include first-order theory; third-order theory; discrete-layer theory (with piecewise linear variation of the in-plane displacements, temperature and electric potential, in the thickness direction); and two predictor-corrector procedures.

Tang, Yvette T.; Noor, Ahmed K.; Xu, Kangming

1995-01-01

96

Prediction of force-time histories in thick steel plates due to penetration by tungsten rods at velocities of 1.5 2.5 km s ?1  

Microsoft Academic Search

An analytical model has been proposed to predict the force time history in an isotropic plate due to penetration by a projectile. The analytical model developed considers the prediction of shape and size of the cavity, pressure distribution along the cavity wall and force-time history for the penetration event. The shape and the radius of the cavity obtained from the

J. E. Saliba; S. Dhar; D. J. Grove; N. S. Brar

1996-01-01

97

Beyond Plate Tectonics: Plate Dynamics  

E-print Network

Plate tectonics dogma has resulted in a variety of theories that frequently violate first principles. In this article it is suggested that ridges are in compression, not tension from convection cells, triple junctions cause hot spots (not vice versa), mantle plumes do not cause hot spot tracks, chord push creates pressures well in excess of lithostatic load, the arch effect demonstrates that rifts form both in compression and tension, surging (i.e. the sudden and rapid motion of the plates) occurs episodically, the presence of a basal shear zone a few meters thick during surging, the preferred initiation of subduction zones at the ridge, revision of the Wilson Cycle, the conformance of old school geologists and plate tectonicians, earth-based non bolide impact mass extinctions, the loss of the earths magnetic field and its subsequent reappearance, additional application of the least work (or maximum

Richard Moody

98

Plating To Reinforce Welded Joints  

NASA Technical Reports Server (NTRS)

Electrodeposition used to strengthen welded joints gouged, nicked, or suffered other mechanical damage. Plating cell, typically of acrylic plastic such as poly (Methylmetacrylate), is assembled around part to be plated. Areas not to be plated are masked with plater's tape. Weld area is plated in standard nickel-plating process.

Otousa, J. E.

1982-01-01

99

Plate Tectonics: 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

100

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

101

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

102

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

103

Plate TectonicsPlate Tectonics Plate TectonicsPlate Tectonics  

E-print Network

Plate TectonicsPlate Tectonics #12;Plate TectonicsPlate Tectonics · Lithosphere ­ strong, rigid, transform boundaries ­ travel 1 to 11 cm/yr relative to one another #12;14 tectonic plates today #12;Mid asthenosphere that flows · 8 large lithospheric plates and 6 smaller ones ­ separated by divergent, convergent

Siebel, Wolfgang

104

Aluminum transfer method for plating plastics  

NASA Technical Reports Server (NTRS)

Electroless plating technique produces plate of uniform thickness. Hardness and abrasion resistance can be increased further by heat treatment. Method results in seamless coating over many materials, has low thermal conductivity, and is relatively inexpensive compared to conventional methods.

Goodrich, W. D.; Stalmach, C. J., Jr.

1977-01-01

105

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

106

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

107

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

108

Standard Test Method for Measuring the Curved Beam Strength of a Fiber-Reinforced Polymer-Matrix Composite - (View Full Text) D6416/D6416M-01(2007) Standard Test Method for Two-Dimensional Flexural Properties of Simply Supported Sandwich Composite Plates Subjected to a Distributed Load  

E-print Network

Standard Test Method for Measuring the Curved Beam Strength of a Fiber-Reinforced Polymer-Matrix Composite - (View Full Text) D6416/D6416M-01(2007) Standard Test Method for Two-Dimensional Flexural Properties of Simply Supported Sandwich Composite Plates Subjected to a Distributed Load

American Society for Testing and Materials. Philadelphia

2001-01-01

109

Violin plate modes.  

PubMed

As the first step toward developing a generic model for the acoustically radiating vibrational modes of the violin and related instruments, the modes of both freely supported and edge-constrained top and back plates have been investigated as functions of shape, arching height, elastic anisotropy, the f-holes and associated island area, thickness graduations, and the additional boundary constraints of the ribs, soundpost, and bass-bar present in the assembled instrument. Comsol shell structure finite element software has been used as a quasi-experimental tool, with physical and geometric properties varied smoothly, often over several orders of magnitude, allowing the development of the plate modes to be followed continuously from those of an initially square plate to those of doubly-arched, guitar-shaped, orthotropic plates and their dependence on all the above factors. PMID:25618046

Gough, Colin

2015-01-01

110

Plate Boundaries  

NSDL National Science Digital Library

This site provides information on plate boundaries, which are found at the edge of the lithospheric plates and are of three types: convergent, divergent and conservative. Wide zones of deformation are usually characteristic of plate boundaries because of the interaction between two plates. The three boundaries are characterized by their distinct motions which are described in the text and depicted with block diagram illustrations, all of which are animated. There are also two maps that show the direction of motion of the plates. Active links lead to more information on plate tectonics.

111

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

112

Standardizing  

NSDL National Science Digital Library

This page, created by Statisical Literacy.com, contains a short article on Simpson's Paradox with an example of how standardizing changes the results. It also contains links to other "real world" articles on Simpson's 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

113

Forming Weld Lands On Metal Plates  

NASA Technical Reports Server (NTRS)

Forming shoe pounds edge of newly inserted plate workpiece. After many passes of shoe and advances of plate, thick land builds up at edge. Workpiece heated to enable metal to flow without strain hardening. Proposed upset-forming process replaces relatively expensive, time-consuming, and wasteful process in which integral weld lands created by machining metal away from plates everywhere except at lands.

Weddendorf, Bruce

1994-01-01

114

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.

115

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

116

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.

2005-12-17

117

Stresa, Italy, 25-27 April 2007 DESIGN AND MODELING OF MICROMECHANICAL GaAs BASED HOT PLATE FOR  

E-print Network

. 1. INTRODUCTION Standard micro hotplates are based on membranes made of silicon nitride and oxide micromechanical hot plates. Mechanical stability and a fast thermal response are especially significant parameters to be designed with the thickness as thin as possible. Additionally, optimization of the MTC structure dimensions

Paris-Sud XI, Université de

118

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

119

Bipolar battery plate  

NASA Technical Reports Server (NTRS)

A liquid-impermeable plate (10) having through-plate conductivity with essentially zero resistance comprises an insulator sheet (12) having a series of spaced perforations (14) each of which contains a metal element (16) sealingly received into the perforation (14). A low-cost plate can readily be manufactured by punching a thermoplastic sheet (40) such as polypropylene with a punching tool (52), filling the apertures with led spheres (63) having a diameter smaller than the holes (50) but larger than the thickness of the sheet, sweeping excess spheres (62) off the sheet with a doctor blade (60) and then pressing a heated platen (74) onto the sheet to swage the spheres into a cylindrical shape and melt the surrounding resin to form a liquid-impermeable collar (4) sealing the metal into the sheet.

Rowlette, John J. (Inventor)

1987-01-01

120

with a uniform standard deviation of 5 L/100. To study the DFG conversion efficiency as a function of the sample thickness L, the  

E-print Network

of the sample thickness L, the samples are bevelled by mechanical polishing to produce wedges with angles of 258 to measure DFG coherence length in ZnSe (,78 mm in the 8­12-mm DFG range)19 . If a resonance is to be found the minimum index dispersion of ZnSe in this spectral region equidistant between the gap and the Restrahlung

Mittleman, Daniel

121

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

122

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

123

Peen plating  

NASA Technical Reports Server (NTRS)

A process for metal plating which comprises spraying a mixture of metallic powder and small peening particles at high velocity against a surface is described. The velocity must be sufficient to impact and bond metallic powder onto the surface. In the case of metal surfaces, the process has as one of its advantages providing mechanical working (hardening) of the surface simultaneously with the metal plating.

Babecki, A. J. (inventor); Haehner, C. L.

1973-01-01

124

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

125

A slotted orifice plate used as a flow measurement device  

E-print Network

The standard orifice plate is used extensively by the natural gas industry for the metering of fuel. Because of the costs associated with errors in flow measurement inherent with the use of a standard orifice plate, any improvements upon...

Macek, Michael Lee

2012-06-07

126

Lightweight, Rack-Mountable Composite Cold Plate/Shelves  

NASA Technical Reports Server (NTRS)

Rack-mountable composite-material structural components that would serve as both shelves and cold plates for removing heat from electronic or other equipment mounted on the shelves have been proposed as lightweight alternatives to all-metal cold plate/shelves now in use. A proposed cold plate/shelf would include a highly thermally conductive face sheet containing oriented graphite fibers bonded to an aluminum honeycomb core, plus an extruded stainless-steel substructure containing optimized flow passages for a cooling fluid, and an inlet and outlet that could be connected to standard manifold sections. To maximize heat-transfer efficiency, the extruded stainless-steel substructure would be connected directly to the face sheet. On the basis of a tentative design, the proposed composite cold plate/shelf would weigh about 38 percent less than does an all-aluminum cold plate in use or planned for use in some spacecraft and possibly aircraft. Although weight is a primary consideration, the tentative design offers the additional benefit of reduction of thickness to half that of the all-aluminum version.

Hurlbert, Kathryn M.; Ruemmele, Warren; Nguyen, Hai D.; Andish, Kambiz; McCalley, Sean

2004-01-01

127

Gas tungsten arc welding procedures for tantalum alloy T-111 (Ta8W--2Hf) plate. Final report, 1971--1972  

Microsoft Academic Search

Methods of eliminating or reducing underbred cracking in multipass GTA ; welds in thick T-111 plate were studied. Single-V butt welds prepared using ; experimental filler metal compositions and standard weld procedures resulted in ; only moderate success in reducing underbred cracking. Subsequent procedural ; changes incorporating manual welding, slower weld speeds, and three or fewer fill ; passes resulted

R. E. Gold; R. L. Kesterson

1973-01-01

128

49 CFR 213.123 - Tie plates.  

Code of Federal Regulations, 2011 CFR

...2011-10-01 2011-10-01 false Tie plates. 213.123 Section 213.123...STANDARDS Track Structure 213.123 Tie plates. (a) In Classes 3 through...timber crossties are in use there shall be tie plates under the running rails on at...

2011-10-01

129

49 CFR 213.123 - Tie plates.  

Code of Federal Regulations, 2012 CFR

...2012-10-01 2012-10-01 false Tie plates. 213.123 Section 213.123...STANDARDS Track Structure 213.123 Tie plates. (a) In Classes 3 through...timber crossties are in use there shall be tie plates under the running rails on at...

2012-10-01

130

49 CFR 213.123 - Tie plates.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 2013-10-01 false Tie plates. 213.123 Section 213.123...STANDARDS Track Structure 213.123 Tie plates. (a) In Classes 3 through...timber crossties are in use there shall be tie plates under the running rails on at...

2013-10-01

131

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

132

Mechanical properties and microstructure of gas tungsten arc welded magnesium AZ91D plates  

Microsoft Academic Search

Gas tungsten arc (GTA) welds were performed on 4-mm thick plates, machined from as-cast magnesium AZ91D ingots. The microstructure and defect formation was investigated by optical and scanning electron microscopy. Mechanical properties were determined by standard tensile tests on small-scale specimens. A wide heat affected zone (HAZ) (>3 mm) was created adjacent to the fusion line that consisted of two

A. Munitz; C. Cotler; A. Stern; G. Kohn

2001-01-01

133

Bipolar battery plate  

NASA Technical Reports Server (NTRS)

A liquid-impermeable plate (10) having throughplate conductivity with essentially zero resistance comprises an insulator sheet (12) having a series of spaced perforations (14) each of which contains a metal element (16) sealingly received into the perforation (14). A low-cost plate can readily be manufactured by punching a thermoplastic sheet (40) such as polypropylene with a punching tool (52), filling the apertures with lead spheres (63) having a diameter smaller than the holes (50) but larger than the thickness of the sheet, sweeping excess spheres (62) off the sheet with a doctor blade (60) and then pressing a heated platen (74) onto the sheet to swage the spheres into a cylindrical shape and melt the surrounding resin to form a liquid-impermeable collar (4) sealing the metal into the sheet.

Rowlette, John J. (Inventor)

1985-01-01

134

Growth Plate Injuries  

MedlinePLUS

Growth Plate Injuries May 2014 Questions and Answers about Growth Plate Injuries This publication contains general information about ... Classification of Growth Plate Injuries What Is the Growth Plate? The growth plate, also known as the ...

135

Martian plate tectonics  

NASA Astrophysics Data System (ADS)

The northern lowlands of Mars have been produced by plate tectonics. Preexisting old thick highland crust was subducted, while seafloor spreading produced thin lowland crust during late Noachian and Early Hesperian time. In the preferred reconstruction, a breakup margin extended north of Cimmeria Terra between Daedalia Planum and Isidis Planitia where the highland-lowland transition is relatively simple. South dipping subduction occured beneath Arabia Terra and east dipping subduction beneath Tharsis Montes and Tempe Terra. Lineations associated with Gordii Dorsum are attributed to ridge-parallel structures, while Phelegra Montes and Scandia Colles are interpreted as transfer-parallel structures or ridge-fault-fault triple junction tracks. Other than for these few features, there is little topographic roughness in the lowlands. Seafloor spreading, if it occurred, must have been relatively rapid. Quantitative estimates of spreading rate are obtained by considering the physics of seafloor spreading in the lower (approx. 0.4 g) gravity of Mars, the absence of vertical scarps from age differences across fracture zones, and the smooth axial topography. Crustal thickness at a given potential temperature in the mantle source region scales inversely with gravity. Thus, the velocity of the rough-smooth transition for axial topography also scales inversely with gravity. Plate reorganizations where young crust becomes difficult to subduct are another constraint on spreading age. Plate tectonics, if it occurred, dominated the thermal and stress history of the planet. A geochemical implication is that the lower gravity of Mars allows deeper hydrothermal circulation through cracks and hence more hydration of oceanic crust so that more water is easily subducted than on the Earth. Age and structural relationships from photogeology as well as median wavelength gravity anomalies across the now dead breakup and subduction margins are the data most likely to test and modify hypotheses about Mars plate tectonics.

Sleep, N. H.

1994-03-01

136

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, Herv; Chryssostalis, Ariane; Robin, Franoise

2013-01-01

137

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

138

Reappraising elastic thickness variation at oceanic trenches  

Microsoft Academic Search

We reassess the variation of elastic thickness as a function of lithospheric plate age using a global database of bathymetric and free-air gravity profiles which are perpendicular to oceanic trenches. As in many previous studies, our starting point is the well-known floating elastic plate model. In order to remove the influence of short-wavelength features not associated with lithospheric bending, adjacent

Madeleine Bry; Nicky White

2007-01-01

139

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

140

Shear bands and cracking of metallic glass plates in bending  

Microsoft Academic Search

The thickness dependence of yielding and fracture of metallic glass plates subjected to bending is considered in terms of the shear band processes responsible for these properties. We argue that the shear band spacing ~and length! scales with the thickness of the plate because of strain relaxation in the vicinity of the shear band at the surface. This is consistent

R. D. Conner; W. L. Johnson; W. D. Nixa; W. D. Nix

2006-01-01

141

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

142

FISSION PLATE POWER MEASUREMENT BY A TRANSIENT-TEMPERATURE METHOD  

Microsoft Academic Search

Transient-temperature behavior following a step change in internal heat ; generation was analyzed to determine the power generation in the Battelle ; Shielding Facility fission plate. The fission plate is employed for shielding ; studies as a radiation source with a fission energy distribution. The plate is a ; 28-in diam, 0.0199-in. thick uranium disk containing 3741 gm of uranium

Anno

1963-01-01

143

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.

144

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

145

Plate motions: fundamentals  

E-print Network

lithospheric plates" · Plate tectonics = a kinematic theory ­ Rigid plates (no intraplate deformation") · Convergent = subductions ("trenches") · Strike-slip = transform faults · Plate tectonics describesPlate motions: fundamentals · Assume a pie-shaped wedge plate B, rotating around E (=rotation pole

Déverchère, Jacques

146

Discrete singular convolution method for buckling analysis of rectangular Mindlin plates  

Microsoft Academic Search

The discrete singular convolution (DSC) method is proposed for solving the elastic buckling problem of thick rectangular plates under a uniaxial compressive loading. To allow for the effect of transverse shear deformation in thick plates, the Mindlin plate theory has been adopted. The numerical results are checked against available analytical and other numerical solutions. It is found that the convergence

H. Ersoy; . Civalek; M. Grses

2009-01-01

147

Plate Tectonics  

NSDL National Science Digital Library

In this activity, presented by the Lane Community College MAPS GIS Program, students will learn the concept of a digital data viewer, and how this resource can help them learn more about plate tectonics. Students will learn terminology associated with both geology and computer aided GIS. The activity is presented as a PDF, and helps the student learn by presenting a series of easy to follow questions. This allows students to learn at their own pace, as it tests their knowledge every step of the way. Visitors will find links to the instructor and student versions of the lesson and links to the web-based GIS utility used in the activity.

2008-12-11

148

Importance of Corneal Thickness  

MedlinePLUS

The Importance of Corneal Thickness email Send this article to a friend by filling out the fields below: Your name: Your friend's name: ... intraocular eye pressure and glaucoma development. Why is Corneal Thickness Important? Corneal thickness is important because it ...

149

Birefringence of Muscovite Mica Plate Temperature Effect in the Ultraviolet and Visible Spectrum  

E-print Network

We developed a method to measure the phase retardation and birefringence of muscovite mica plate in the temperature range of 223K to 358K within the spectrum of 300 to 700 nm. The phase retardation data is gained through the standard transmission ellipsometry using spectroscopic ellipsometer. With the phase retardation and thickness of the mica plate we can calculate its birefringence dispersion. Our results give abundant phase retardation and birefringence data of muscovite mica in the ultraviolet and visible spectrum from 223K to 358K. From the experimental data, the phase retardation and birefringence will drop down at the fixed wavelength when the temperature rises. The accuracy of the birefringence of mica plate is better than 3.5e-5.

Zhang, Xu; Qi, Limei; Zhang, Xia; Hao, Dianzhong

2014-01-01

150

Plate mouse  

PubMed Central

Fracture shaft humerus when surgically fixed is known to go into non-union and one of the main reasons of this is implant failure. The causes of implant failure may lie in the fracture personality, faulty implant material or choice, dubious surgical technique & faulty mechanics of fixation. Implants may break and cut-through but a unique type of implant migration from one surgical compartment to the other or one anatomical part of body to the other has not been hitherto reported. A 45-year-old male, farmer by occupation, was operated for fracture shaft of humerus 15 years back. He presented to us because of pain due to subcutaneous presence of plate in forearm. X-ray of the elbow with forearm showed that the plate used for fixation of humerus had migrated from one body part to another that is from arm to forearm. The patient on deliberation regarding the pros and cons of surgical treatment options, chose not to get his humerus non-union resolved surgically. This was because he could do his activities related to farming reasonably well.

Lal, Hitesh; Sharma, Deepak Kumar; Mittal, Deepak

2012-01-01

151

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

152

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

153

30 CFR 57.12032 - Inspection and cover plates.  

...LABOR METAL AND NONMETAL MINE SAFETY AND HEALTH SAFETY AND HEALTH STANDARDS-UNDERGROUND METAL AND NONMETAL MINES Electricity Surface and Underground 57.12032 Inspection and cover plates. Inspection and cover plates on electrical...

2014-07-01

154

30 CFR 56.12032 - Inspection and cover plates.  

...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...

2014-07-01

155

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

156

Heat Treatment of Friction-Stir-Welded 7050 Aluminum Plates  

NASA Technical Reports Server (NTRS)

A method of heat treatment has been developed to reverse some of the deleterious effects of friction stir welding of plates of aluminum alloy 7050. This alloy is considered unweldable by arc and high-energy-density beam fusion welding processes. The alloy can be friction stir welded, but as-welded workpieces exhibit low ductility, low tensile and yield strengths, and low resistance to stress corrosion cracking. Heat treatment according to the present method increases tensile and yield strengths, and minimizes or eliminates stress corrosion cracking. It also increases ductility. This method of heat treatment is a superior alternative to a specification-required heat treatment that caused the formation of large columnar grains, which are undesired. Workpieces subjected to the prior heat treatment exhibited elongations <2 percent, and standard three-point bend specimens shattered. The development of the present heat treatment method was guided partly by the principles that (1) by minimizing grain sizes and relieving deformation stresses, one can minimize or eliminate stress corrosion cracking and (2) the key to maximizing strength and eliminating residual stresses is to perform post-weld solution heating for as long a time as possible while incurring little or no development of large columnar grains in friction stir weld nuggets. It is necessary to perform some of the solution heat treatment (to soften the alloy and improve machine welding parameters) before welding. The following is an example of thickness- dependent pre- and post-weld heat treatments according to the present method: For plates 0.270 in. (approx.6.86 mm) thick milled from plates 4.5 in. (114.3 mm) thick, perform pre-weld solution heating at 890 F (477 C) for 1 hour, then cool in air. After friction stir welding, perform solution heating for 10 minutes, quench, hold at room temperature for 96 hours, then age at 250 F (121 C) for 5 hours followed by 325 F (163 C) for 27 hours.

Petter, George E.; Figert, John D.; Rybicki, Daniel J.; Burns, Timothy

2006-01-01

157

Quaternions as astrometric plate constants  

NASA Technical Reports Server (NTRS)

A new method for solving problems in relative astrometry is proposed. In it, the relationship between the measured quantities and the components of the position vector of a star is modeled using quaternions, in effect replacing the plate constants of a standard four-plate-constant solution with the four components of a quaternion. The method allows a direct solution for the position vectors of the stars, and hence for the equatorial coordinates. Distortions, magnitude, and color effects are readily incorporated into the formalism, and the method is directly applicable to overlapping-plate problems. The advantages of the method include the simplicity of the resulting equations, their freedom from singularities, and the fact that trigonometric functions and tangential point transformations are not needed to model the plate material. A global solution over the entire sky is possible.

Jefferys, William H.

1987-01-01

158

An elastic plate model for interseismic deformation in subduction Ravi V. S. Kanda1  

E-print Network

the subducting and overriding plates, as well as zero net steady state vertical offset between the two plates, 1983]. The BSM accomplishes this zero net strain in the overriding plate by parameterizing interseismic case of zero plate thickness, thereby providing an alternative motivation for the BSM. The ESPM also

159

New heat transfer and friction factor design data for perforated plate heat exchangers  

Microsoft Academic Search

Perforated plate heat exchangers have been found to have inherently low axial conduction and are therefore excellent candidates for cryogenic applications where an all-metal design is required. A total of three plate cores were tested; two were chemically etched and the other mechanically punched. Hole size, percent open area and plate thickness parameters were varied among the plates. Experimental results

Richard H. Hubbell; Christina L. Cain

1988-01-01

160

Plastic Analysis and Design of Steel Plate Shear Walls Jeffrey Berman, M.ASCE,1  

E-print Network

. In this procedure the thickness of the infill plate is found using equations that are derived from the plastic analysis of the strip model, which is an accepted model for the representation of steel plate shear walls of the infill plates. This led engineers to design heavily stiffened plates that offered little economic

Bruneau, Michel

161

Non-linear static and dynamic analysis of stiffened laminated plates  

Microsoft Academic Search

The static and dynamic analysis of eccentrically stiffened laminated plates is presented. For large deformations, the von Karman kinematic relations of the plate and stiffener are considered in the formulation. Also, the formulation accounts for transverse shear deformation effects of the plate and stiffener, and the model is applicable for the analysis of both thin and thick stiffened laminated plates.

M. Kolli; K. Chandrashekhara

1997-01-01

162

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

163

Mechanical properties of Indonesian-made narrow dynamic compression plate.  

PubMed

Osteosynthesis plates are clinically used to fixate and position a fractured bone. They should have the ability to withstand cyclic loads produced by muscle contractions and total body weight. The very high demand for osteosynthesis plates in developing countries in general and in Indonesia in particular necessitates the utilisation of local products. In this paper, we investigated the mechanical properties, i.e. proportional limit and fatigue strength of Indonesian-made Narrow Dynamic Compression Plates (Narrow DCP) as one of the most frequently used osteosynthesis plates, in comparison to the European AO standard plate, and its relationship to geometry, micro structural features and surface defects of the plates. All Indonesian-made plates appeared to be weaker than the standard Narrow DCP because they consistently failed at lower stresses. Surface defects did not play a major role in this, although the polishing of the Indonesian Narrow DCP was found to be poor. The standard plate showed indications of cold deformation from the production process in contrast to the Indonesian plates, which might be the first reason for the differences in strength. This is confirmed by hardness measurements. A second reason could be the use of an inferior version of stainless steel. The Indonesian plates showed lower mechanical behaviour compared to the AO-plates. These findings could initiate the development of improved Indonesian manufactured DCP-plates with properties comparable to commonly used plates, such as the standard European AO-plates. PMID:22842280

Dewo, P; van der Houwen, E B; Sharma, P K; Magetsari, R; Bor, T C; Vargas-Llona, L D; van Horn, J R; Busscher, H J; Verkerke, G J

2012-09-01

164

Polymeric composite bipolar plates for vehicle applications  

Microsoft Academic Search

At present membrane electrode assembly performance levels and stack operating conditions of PEM fuel cells, a plate area specific resistance of less than approximately 20m?cm2 and a plate thickness of less than 2mm are required to meet the vehicular volumetric power density target (>2kWl?1). It is, however, difficult to meet these aggressive requirements, and simultaneously obtain good mechanical properties when

Richard Blunk; Mahmoud Hassan Abd Elhamid; Daniel Lisi; Youssef Mikhail

2006-01-01

165

Flat Plate Cascades at Supersonic Speed  

NASA Technical Reports Server (NTRS)

A brief review of exact two-dimensional supersonic flow theory and Ackeret's linearized theory are first presented. The lift and drag coefficients of a cascade of flat plates are calculated exactly and compared to those obtained using the linearized theory. The forces on the cascade are determined for unsteady inlet flow. The flat plate cascade theory is extended to compute the efficiency of a supersonic propeller with friction and finite blade thickness.

El Badrawy, Rashad M

1956-01-01

166

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

167

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

168

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

169

Thick GEM with a resistive coating  

NASA Astrophysics Data System (ADS)

The results of testing a detector based on a thick gas electron multiplier (GEM) are presented. Impact of the TGEM dielectric charging on detector physical parameters is assessed based on simulation and experimental results. The further development of the detectorTGEM with resistive coating was constructed and tested. The test results are presented and compared to a standard thick GEM.

Vankov, I.; Vasilev, S. E.; Golutvin, I. A.; Ershov, Yu. V.; Karjavin, V. Yu.; Makankin, A. M.; Perelygin, V. V.; Chekhovski, V. A.

2013-12-01

170

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

171

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

172

Growth Plate Fractures  

MedlinePLUS

... 2013 by the American Academy of Orthopaedic Surgeons. Growth Plate Fractures Description The bones of children and ... also subject to a unique injury called a growth plate fracture. Growth plates are areas of developing ...

173

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

174

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...

175

Risk factors associated with bulk tank standard plate count, bulk tank coliform count, and the presence of Staphylococcus aureus on organic and conventional dairy farms in the United States.  

PubMed

The purpose of this study was to assess the association of bulk tank milk standard plate counts, bulk tank coliform counts (CC), and the presence of Staphylococcus aureus in bulk tank milk with various management and farm characteristics on organic and conventional dairy farms throughout New York, Wisconsin, and Oregon. Data from size-matched organic farms (n=192), conventional nongrazing farms (n=64), and conventional grazing farms (n=36) were collected at a single visit for each farm. Of the 292 farms visited, 290 bulk tank milk samples were collected. Statistical models were created using data from all herds in the study, as well as exclusively for the organic subset of herds. Because of incomplete data, 267 of 290 herds were analyzed for total herd modeling, and 173 of 190 organic herds were analyzed for the organic herd modeling. Overall, more bulk tanks from organic farms had Staph. aureus cultured from them (62% of organic herds, 42% conventional nongrazing herds, and 43% of conventional grazing herds), whereas fewer organic herds had a high CC, defined as ?50 cfu/mL, than conventional farms in the study. A high standard plate count (1,000 cfu/mL) was associated with decreased body condition score of adult cows and decreased milk production in both models. Several variables were significant only in the model created using all herds or only in organic herds. The presence of Staph. aureus in the bulk tank milk was associated with fewer people treating mastitis, increased age of housing, and a higher percentage of cows with 3 or fewer teats in both the organic and total herd models. The Staph. aureus total herd model also showed a relationship with fewer first-lactation animals, higher hock scores, and less use of automatic takeoffs at milking. High bulk tank CC was related to feeding a total mixed ration and using natural service in nonlactating heifers in both models. Overall, attentive management and use of outside resources were useful with regard to CC on organic farms. In all models except the organic CC model, we observed an association with the average reported somatic cell count from 3 mo before the herd visit, indicating that many of the regularly tested milk quality parameters are interconnected. In conclusion, we found that conventional and organic farms are similar in regard to overall herd management, but each grazing system faces unique challenges when managing milk quality. PMID:24140332

Cicconi-Hogan, K M; Gamroth, M; Richert, R; Ruegg, P L; Stiglbauer, K E; Schukken, Y H

2013-12-01

176

Steady incompressible variable thickness shear layer aerodynamics  

NASA Technical Reports Server (NTRS)

A shear flow aerodynamic theory for steady incompressible flows is presented for both the lifting and non lifting problems. The slow variation of the boundary layer thickness is considered. The slowly varying behavior is treated by using multitime scales. The analysis begins with the elementary wavy wall problem and, through Fourier superpositions over the wave number space, the shear flow equivalents to the aerodynamic transfer functions of classical potential flow are obtained. The aerodynamic transfer functions provide integral equations which relate the wall pressure and the upwash. Computational results are presented for the pressure distribution, the lift coefficient, and the center of pressure travel along a two dimensional flat plate in a shear flow. The aerodynamic load is decreased by the shear layer, compared to the potential flow. The variable thickness shear layer decreases it less than the uniform thickness shear layer based upon equal maximum shear layer thicknesses.

Chi, M. R.

1976-01-01

177

Vibration of circular plates, of several thicknesses, with three supports  

E-print Network

~mplitudes Found. by t, he Amplitude Pickup Instruments for l/8- in. Plat e 0 ~ 0 ~ 0 ~ eeoc' Bibliography ~ o ~ eoaa gaea VIBRATION OP CIRCULAR PLi'. TZS, OF SEVERAL THICi'KZSSZS, ;11TH THREE SUFPORTS INTRODUCTION The different. 1al equations for the vibrat.... ion of thin plat, es ancl clast, ic bodies with cert, ain simple boundary conditions snd. certain definite support configurations have been solved, Many texts on vibrations have these solut, iona, but their' solution reouires idea3. 1zations...

Ballentine, John Richard

2012-06-07

178

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

179

Inevitability of Plate Tectonics on Super-Earths  

E-print Network

The recent discovery of super-Earths (masses ? 10 M?) has initiated a discussion about conditions for habitable worlds. Among these is the mode of convection, which influences a planets thermal evolution and surface conditions. On Earth, plate tectonics has been proposed as a necessary condition for life. Here we show, that super-Earths will also have plate tectonics. We demonstrate that as planetary mass increases, the shear stress available to overcome resistance to plate motion increases while the plate thickness decreases, thereby enhancing plate weakness. These effects contribute favorably to the subduction of the lithosphere, an essential component of plate tectonics. Moreover, uncertainties in achieving plate tectonics in the one earth-mass regime disappear as mass increases: super-Earths, even if dry, will exhibit plate tectonic behaviour. Subject headings: planetary systems planets and satellites Earth 1 corresponding author 2

Diana Valencia; Richard J. Oconnell; Dimitar D. Sasselov

180

Inevitability of Plate Tectonics on Super-Earths  

E-print Network

The recent discovery of super-Earths (masses less or equal to 10 earth-masses) has initiated a discussion about conditions for habitable worlds. Among these is the mode of convection, which influences a planet's thermal evolution and surface conditions. On Earth, plate tectonics has been proposed as a necessary condition for life. Here we show, that super-Earths will also have plate tectonics. We demonstrate that as planetary mass increases, the shear stress available to overcome resistance to plate motion increases while the plate thickness decreases, thereby enhancing plate weakness. These effects contribute favorably to the subduction of the lithosphere, an essential component of plate tectonics. Moreover, uncertainties in achieving plate tectonics in the one earth-mass regime disappear as mass increases: super-Earths, even if dry, will exhibit plate tectonic behaviour.

Valencia, Diana; Sasselov, Dimitar D

2007-01-01

181

Inevitability of Plate Tectonics on Super-Earths  

E-print Network

The recent discovery of super-Earths (masses less or equal to 10 earth-masses) has initiated a discussion about conditions for habitable worlds. Among these is the mode of convection, which influences a planet's thermal evolution and surface conditions. On Earth, plate tectonics has been proposed as a necessary condition for life. Here we show, that super-Earths will also have plate tectonics. We demonstrate that as planetary mass increases, the shear stress available to overcome resistance to plate motion increases while the plate thickness decreases, thereby enhancing plate weakness. These effects contribute favorably to the subduction of the lithosphere, an essential component of plate tectonics. Moreover, uncertainties in achieving plate tectonics in the one earth-mass regime disappear as mass increases: super-Earths, even if dry, will exhibit plate tectonic behaviour.

Diana Valencia; Richard J. O'Connell; Dimitar D. Sasselov

2007-10-03

182

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

183

Minimal Pixilated Resistive Plate Chamber  

NASA Astrophysics Data System (ADS)

Two conducting plates, separated by a suitable gas at atmospheric pressure, can be used as a detector for minimum ionizing particles. However, if a spark develops the energy carried by the spark can damage the surface of the plates. The energy available to a spark can be reduced to a harmless level by covering one of the plates with a material with a high resistance. This insulating layer must be thick enough so that transient voltages do not punch holes in the layer (0.2-0.5 mm). The resistance between the front and the back of the layer needs to be large but still small enough so that the surface charge can be replenished in a time of the order of one microsecond. This requires a resistance of the order of 500 M?/cm^2, which is in the range of ceramic enamels that are made for application to metal surfaces. The other plate can be divided into pixels, in effect making a number of separate detectors.

Norbeck, Edwin; Onel, Yasar

2009-10-01

184

Transient waves in inhomogeneous isotropic elastic plates  

Microsoft Academic Search

Summary This paper deals with the problem of transient wave propagation in isotropic inhomogeneous elastic Cosserat plates of uniform thickness by the method of singular wave curves. The transport equations governing the growth-decay behaviour of all extensional and bending wave modes are explicitly integrated to provide a common general formula involving the material parameters and wave geometry. An example of

H. Cohen; R. S. D. Thomas

1984-01-01

185

A refined higher-order C plate bending element  

Microsoft Academic Search

A general finite element formulation for plate bending problem based on a higher-order displacement model and a threedimensional state of stress and strain is attempted. The theory incorporates linear and quadratic variations of transverse normal strain and transverse shearing strains and stresses respectively through the thickness of the plate. The 9-noded quadrilateral from the family of two dimensional Co continuous

TARUN KANT; D. R. J. OWENS; C. ZIENKIEWICZQ

1982-01-01

186

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

187

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. PMID:22685377

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

2010-01-01

188

Copper plating on the polyimide film by electroless plating techniques for EMI shielding.  

PubMed

In this work, the metal plated film was prepared by electroless plating techniques. The film was prepared for the fabrication of EMI shielding. Polyimide film was treated by base solution for etching and then activated by silver. The modified polyimide film was immersed into the electroless copper plating solution which has different molar ratios of nickel in the solution. The thickness and surface morphology of copper layer on the polyimide films were characterized with scanning electron microscopy (SEM). Furthermore, EMI shielding ability of the film was calculated by measuring reflectivity of EM wave on the film surface using the equation of Schelkunoff theory. PMID:19908729

Ji, Eun Sun; Cha, Hyun Gil; Kim, Chang Woo; Kang, Dong In; Kang, Young Soo

2009-12-01

189

Isopachic contouring of opaque plates  

NASA Technical Reports Server (NTRS)

Contour maps of change of thickness of opaque plates subjected to external loads are obtained using holographic interferometry in conjunction with the moire effect. A simple holographic-interferometry arrangement is used first to obtain contour maps of the out-of-plane displacements of the two sides of the object. Carrier patterns of equal magnitude but opposite signs are added to these contours. Superposition of the reconstructed holograms of the two sides produces a pattern of additive-moire fringes, which are contours of change of thickness. Effects of midplane warpage of the loaded specimen are cancelled. Sensitivity is lambda/2 per fringe order, contrast of the isopachic-fringe pattern is excellent, and the process is compatible with a mechanical-testing-machine environment.

Post, D.; Asundi, A.; Czarnek, R.

1984-01-01

190

Accurate stress resultants equations for laminated composite deep thick shells  

SciTech Connect

This paper derives accurate equations for the normal and shear force as well as bending and twisting moment resultants for laminated composite deep, thick shells. The stress resultant equations for laminated composite thick shells are shown to be different from those of plates. This is due to the fact the stresses over the thickness of the shell have to be integrated on a trapezoidal-like shell element to obtain the stress resultants. Numerical results are obtained and showed that accurate stress resultants are needed for laminated composite deep thick shells, especially if the curvature is not spherical.

Qatu, M.S. [Franklin Univ., Columbus, OH (United States)

1995-11-01

191

Pavement Thickness Design Parameter  

E-print Network

consuming · Several methods available, but design information generally the same · Terminology: #12;Pavement Thickness Design · Good design uses these parameters: ­ Soil characteristics (subgrade) ­ Soil compaction Distribution ­ HMA ­ PCC #12;Pavement Thickness Design · Soil Resilient Modulus MR ­ Property of the soil

192

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

193

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

194

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

195

Thickness distribution of Antarctic sea ice  

NASA Astrophysics Data System (ADS)

Ship-based observations are used to describe regional and seasonal changes in the thickness distribution and characteristics of sea ice and snow cover thickness around Antarctica. The data set comprises 23,373 observations collected over more than 2 decades of activity and has been compiled as part of the Scientific Committee on Antarctic Research (SCAR) Antarctic Sea Ice Processes and Climate (ASPeCt) program. The results show the seasonal progression of the ice thickness distribution for six regions around the continent together with statistics on the mean thickness, surface ridging, snow cover, and local variability for each region and season. A simple ridge model is used to calculate the total ice thickness from the observations of level ice and surface topography, to provide a best estimate of the total ice mass, including the ridged component. The long-term mean and standard deviation of total sea ice thickness (including ridges) is reported as 0.87 0.91 m, which is 40% greater than the mean level ice thickness of 0.62 m. Analysis of the structure function along north/south and east/west transects revealed lag distances over which sea ice thickness decorrelates to be of the order of 100-300 km, which we use as a basis for presenting near-continuous maps of sea ice and snow cover thickness plotted on a 2.5 5.0 grid.

Worby, Anthony P.; Geiger, Cathleen A.; Paget, Matthew J.; van Woert, Michael L.; Ackley, Stephen F.; Deliberty, Tracy L.

2008-05-01

196

a Study of Transverse Normal Stress Effect on Vibration of Multilayered Plates and Shells  

NASA Astrophysics Data System (ADS)

This paper evaluates transverse normal stress ?zzeffect on vibration of multilayered structures. To this purpose a mixed plate model initially introduced by Toledano and Murakami has been extended to dynamics analysis of double curved shells. These models allow both continuous interlaminar transverse shear and normal stresses as well as the zigzag form of the displacement distribution in the shell thickness directions to be modelled. Governing equations have been derived by employing a Reissner's mixed theorem. Classical models on the basis of standard displacement formulations have been considered for comparison purposes. The evaluations of transverse stress effects have been conducted by comparing constant, linear and higher order distributions of transverse displacement components in the plate thickness directions. Free vibrational response of layered, simply supported plates, cylindrical and spherical shells made of isotropic as well as orthotropic layers has been analyzed. The numerical investigation carried out and comparison with earlier results has concluded that:1. The possibility of describing interlaminar continuous transverse normal stress makes the mixed theories more attractive with respect to other available modelling.2. Any refinements of classical models are meaningless, unless the effects of interlaminar continuous transverse shear and normal stresses are both taken into account in a multilayered shell theory.

CARRERA, E.

1999-09-01

197

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.

198

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

199

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.

200

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

201

Penetration of DH-36 steel plates with and without polyurea coating Liang Xue a  

E-print Network

Penetration of DH-36 steel plates with and without polyurea coating Liang Xue a , Willis Mock Jr. b c l e i n f o Article history: Received 26 January 2010 Received in revised form 18 August 2010 scenarios are considered: (1) a blank (unbacked) steel plate; (2) the same steel plate backed by a thick

Xue, Liang

202

Optical and thermal performance of a remote phosphor plate  

NASA Astrophysics Data System (ADS)

The objective of this study was to understand how optical and thermal performances are impacted in a remote phosphor LED (light-emitting diode) system when the phosphor plate thickness and phosphor concentration change with a fixed amount of a commonly used YAG:Ce phosphor. In the first part of this two-part study, an optical raytracing analysis was carried out to quantify the optical power and the color properties as a function of remote phosphor plate thickness, and a laboratory experiment was conducted to verify the results obtained from the raytracing analysis and also to examine the phosphor temperature variation due to thickness change.

Mou, Xi; Narendran, Nadarajah; Zhu, Yiting; Perera, Indika U.

2014-09-01

203

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

204

FEP-171 resist thickness optimization and dry etch screening on NTAR7 chrome substrates for Sigma7300 DUV laser pattern generator  

NASA Astrophysics Data System (ADS)

Chrome and resist thickness are limiting factors for final resolution on mask. The trend in mask manufacturing is consequently moving towards thinner chrome and resist films. The Sigma7300 is a 248nm DUV laser pattern generator with optical resolution approaching 100nm. The earlier standard mask blank for the mask writer had 1030 thick AR8 chrome together with 4000 FEP-171 resist. To fully benefit from the resolution capability of the mask writer, this study aimed to investigate the 730 thick NTAR7 chrome together with thinner FEP-171 resist. The dry etch characteristics of thin chrome and thin resist were also studied. As a first step, a set of plates with varying resist thickness was exposed to extract the swing curve. The resist thickness ranged from 3050 - 3600 in steps of 50. The fitted curve based on the dose required to break through the resist (dose-to-clear) for different thicknesses showed a maximum at approximately 3200. A resolution improvement of about 10nm was achieved in this resist thickness compared to the earlier 4000 film. Design of Experiments (DoE) was used to perform a screening of the dry etch process on NTAR7 and the 3200 resist. All plates were exposed using the Sigma7300. Etching was performed on a UNAXIS Gen III Mask Etcher with standard Cl2/O2/He gas mixture. The dry etch process developed from the DoE responses was used to characterize the lithographic performance on mask from the Sigma7300 together with the new optimized blanks. CD linearity <10nm (range) was demonstrated both for clear and dark isolated lines down to 180nm line width. Global CD uniformity <6nm (3s) was achieved and very well defined chrome profiles for 150nm isolated clear lines and 130 nm isolated dark lines were demonstrated.

Karlsson, Johan O.; Xing, Kezhao; Bajramovic, Adisa; Dahlberg, Henrik; Bjornberg, Charles; Hogfeldt, Peter; Kjellberg, Lars; Fosshaug, Hans; Dahlberg, Anna; Lundvall, Axel

2004-12-01

205

Rotatable shear plate interferometer  

DOEpatents

A rotatable shear plate interferometer comprises a transparent shear plate mounted obliquely in a tubular supporting member at 45.degree. with respect to its horizontal center axis. This tubular supporting member is supported rotatably around its center axis and a collimated laser beam is made incident on the shear plate along this center axis such that defocus in different directions can be easily measured.

Duffus, Richard C. (Livermore, CA)

1988-01-01

206

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.

207

Computerized Ultrasonic Testing System (CUTS) for in-process thickness determination  

NASA Technical Reports Server (NTRS)

A Computerized Ultrasonic Testing System (CUTS) was developed to measure, in real-time, the rate of deposition and thickness of chromium plated on the inside of thick steel tubes. The measurements are made from the outside of the tubes with the ultrasonic pulse-echo technique. The resolution of the system is 2.5 micron. (0.0001 in.) and the accuracy is better than 10 micron (0.0004 in.). The thickness is measured using six transducers mounted at different locations on the tube. In addition, two transducers are mounted on two reference standards, thereby allowing the system to be continuously calibrated. The tube temperature varies during the process, thus the input from eight thermocouples, located at the measurement sites, is used to calculate and compensate for the change in return time of the ultrasonic echo due to the temperature dependence of the sound velocity. CUTS is applicable to any commercial process where real-time change of thickness of a sample has to be known, with the advantage of facilitating increased efficiency and of improving process control.

Frankel, J.; Doxbeck, M.; Schroeder, S. C.; Abbate, A.

1994-01-01

208

Delamination characterization of composite plates with holes/inclusions under general in-plane loading  

E-print Network

/epoxy plates under tensile loads l5) . The FEM model The quasi ? 3D isoparametric element Representative model showing Guassian points in mesh 1' or the evalu- ation of stresses along the interfaces and free edge FEM model used to evaluate strain energy... to uniaxial tension . . . . . . . . . . . . . 35 Interlaminar stresses through the thickness at the free edge for a plate with a through hole subjected to uniaxial tension . . . . . . . . . 36 Maximum interlaminar stresses through the thickness for a, plate...

Bense, Ronald

2012-06-07

209

Linear versus nonlinear theories for laminated composite plates and shells  

SciTech Connect

Linear and nonlinear shear-deformation theories for laminated composite plates and shells are discussed in this paper. The emphasis here is on the range of validity for each class of theories. The finite element method is used to determine the maximum stresses for a wide range of statically loaded plate and shell panels with various thickness ratios. This paper concludes that for the vast majority of composite materials and for moderately thick plates and shells, stresses normally reach the maximum allowable stress before nonlinear terms can become important. This has been demonstrated by showing that for the limiting case of shear deformation theories (in which the minimum span length (or radius) to thickness ratio is 20), the material usually fails before the maximum deflection reaches the magnitude of the thickness (where nonlinear terms start to become significant).

Qatu, M.S. [Franklin Univ., Columbus, OH (United States)

1995-11-01

210

Thickness-shear and thickness-twist modes in an AT-cut quartz acoustic wave filter.  

PubMed

We studied thickness-shear and thickness-twist vibrations of a monolithic, two-pole crystal filter made from a plate of AT-cut quartz. The scalar differential equations derived by Tiersten and Smythe for electroded and unelectroded quartz plates were employed which are valid for both the fundamental and the overtone modes. Exact solutions for the free vibration resonant frequencies and modes were obtained from the equations. For a structurally symmetric filter, the modes can be separated into symmetric and antisymmetric ones. Trapped modes with vibrations mainly under the electrodes were found. The effect of the distance between the two pairs of electrodes was examined. PMID:25627930

Zhao, Zinan; Qian, Zhenghua; Wang, Bin; Yang, Jiashi

2015-04-01

211

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

212

Adjustable orifice plate seal  

SciTech Connect

This patent describes an orifice fitting of the type having a body with a flow passage for connecting into a pipeline, an orifice plate seal seat located in a slot in the flow passage, a plate carrier which carries an orifice plate having a orifice for the passage of fluid, and gear means in the body for moving the plate carrier from an inactive position out of the flow passage to an active position in the slot in engagement with the seat and with the orifice plate in the flow passage, an improved mans for sealing the orifice plate against the seat. It comprises the plate carrier having a mounting hole therethrough which has an axis, the orifice plate locating in the mounting hole with the orifice concentric with the axis; an annular seal member located on a downstream side of the plate carrier and encircling the mounting hole, the seal member having a downstream face for engaging the seat; a retaining ring located in the mounting hole, sandwiching the orifice plate between the retaining ring and the seal member; mounting means for mounting the retaining ring to the plate carrier so that the retaining ring may protrude in an upstream direction from the plate carrier by an amount that may be adjusted to fit the axial width of the slot; and wherein the mounting means comprises: a set of threads on the perimeter of the retaining ring which engages the threads in the mounting hole, so that rotating the retaining ring relative to the plate carrier will provide a selected protrusion of the retaining ring from the plate carrier; and set screws located in threaded apertures spaced around the retaining ring and extending through the retaining ring into engagement with the orifice plate, so that rotating the set screws in one direction in the threaded.

Foster, J.H.; Beson, J.

1992-03-10

213

An improved plating process  

NASA Technical Reports Server (NTRS)

An alternative to the immersion process for the electrodeposition of chromium from aqueous solutions on the inside diameter (ID) of long tubes is described. The Vessel Plating Process eliminates the need for deep processing tanks, large volumes of solutions, and associated safety and environmental concerns. Vessel Plating allows the process to be monitored and controlled by computer thus increasing reliability, flexibility and quality. Elimination of the trivalent chromium accumulation normally associated with ID plating is intrinsic to the Vessel Plating Process. The construction and operation of a prototype Vessel Plating Facility with emphasis on materials of construction, engineered and operational safety and a unique system for rinse water recovery are described.

Askew, John C.

1994-01-01

214

Coherent radar ice thickness measurements over the Greenland ice sheet  

E-print Network

; : ': ' : :  t52 50--\\"-\\" I ; ; ' . \\"- I ,---T- - ; : ;..,- ........ . ...... I ' --- Red solid line = Flight lines which have data i -o. .i ........ .........  .............. --:-. - :. Plate 1. Locations of ice thickness data collected... of the ice sheet. (The radar data have been averaged over a distance covered by aircraft in 1 s (-130 m).) GOGINENI ET AL.: COHERENT RADAR ICE THICKNESS MEASUREMENTS 33,765 100 ? I 2O0 300 6O0 700-. 800- 900- 1000  Ice -. bedrock Interface 100...

Gogineni, S. Prasad; Tammana, Dilip; Braaten, David A.; Leuschen, C.; Legarsky, J.; Kanagaratnam, P.; Stiles, J.; Allen, C.; Jezek, K.; Akins, T.

2001-12-27

215

Measuring Thicknesses Of Vacuum-Deposited Organic Thin Films  

NASA Technical Reports Server (NTRS)

Method of measuring thickness of thin organic liquid film deposited in vacuum involves use of quartz-crystal monitor (QCM) calibrated by use of witness plate that has, in turn, calibrated by measurement of absorption of infrared light in deposited material. Present procedure somewhat tedious, but once calibration accomplished, thicknesses of organic liquid deposits monitored in real time and in situ by use of QCM.

David, Carey E.

1996-01-01

216

Multicolor printing plate joining  

NASA Technical Reports Server (NTRS)

An upper plate having ink flow channels and a lower plate having a multicolored pattern are joined. The joining is accomplished without clogging any ink flow paths. A pattern having different colored parts and apertures is formed in a lower plate. Ink flow channels each having respective ink input ports are formed in an upper plate. The ink flow channels are coated with solder mask and the bottom of the upper plate is then coated with solder. The upper and lower plates are pressed together at from 2 to 5 psi and heated to a temperature of from 295 F to 750 F or enough to melt the solder. After the plates have cooled and the pressure is released, the solder mask is removed from the interior passageways by means of a liquid solvent.

Waters, W. J. (inventor)

1984-01-01

217

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

218

Crustal Thickness of Iran Inferred from Converted Waves  

NASA Astrophysics Data System (ADS)

The Iranian plate is part of the Alpine-Himalayan orogenic belt, which has been formed by the continental collision between the Arabian and Eurasian plates. The present-day Iranian plate is characterized by diverse tectonic domains including mountain belts (e.g. Zagros and Alborz, Kopeh-Dagh) and oceanic plate subduction (e.g. Makran). Here we present the lateral variations of the Moho discontinuity beneath Iran using a detailed P receiver function study. Our results allow for more precise estimations of the crustal thickness and enable us to provide a detailed Moho depth map for all of Iran for the first time. We used the teleseismic events recorded from 1995 to 2011 at 77 national permanent stations (24 broadband and 53 short period stations). Our results show significant variations in the crustal thickness, which are related to the different geological features within Iran. In general, the average crustal thickness beneath Iran is about 40-45 km. A relatively thick crust of about 54 2 km due to the shortening is observed beneath the Alborz mountain ranges. The crust beneath the Alborz zone shows a thickness changing from 47 2 to 45 2 km from west to east and reaches a thickness of about 50 2 km beneath the Kopeh-Dagh mountain range. We find the thinnest crust of about 33 2 km beneath the Makran subduction zone in southeast Iran showing a normal continental crust, which has not been influenced by collisional processes. The thickest crust (~66 2 km) is locally observed beneath the Sanandaj-Sirjan Zone, which is considered the suture zone of the collision between the Arabian and Eurasian plates.

Taghizadeh-Farahmand, Fataneh; Afsari, Narges; Sodoudi, Forough

2015-02-01

219

Near-absolute Hugoniot measurements in aluminum to 500 GPa using a magnetically accelerated flyer plate technique  

NASA Astrophysics Data System (ADS)

Hugoniot measurements were performed on aluminum (6061-T6) in the stress range of 100-500 GPa (1-5 Mbar) using a magnetically accelerated flyer plate technique. This method of flyer plate launch utilizes the high currents, and resulting magnetic fields produced at the Sandia Z Accelerator to accelerate macroscopic aluminum flyer plates (approximately 1225 mm in lateral dimension and 300 ?m in thickness) to velocities in excess of 20 km/s. This technique was used to perform plate-impact shock-wave experiments on aluminum to determine the high-stress equation of state (EOS). Using a near-symmetric impact method, Hugoniot measurements were obtained in the stress range of 100-500 GPa. The results of these experiments are in excellent agreement with previously reported Hugoniot measurements of aluminum in this stress range. The agreement at lower stress, where highly accurate gas gun data exist, establishes the magnetically accelerated flyer plate technique as a suitable method for generating EOS data. Furthermore, the present results exhibit increased accuracy over the previous techniques used to obtain data in the higher-stress range. This improved accuracy enhances our understanding of the response of aluminum to 500 GPa, and lends increased confidence to the use of aluminum as a standard material in future impedance matching experiments.

Knudson, M. D.; Lemke, R. W.; Hayes, D. B.; Hall, C. A.; Deeney, C.; Asay, J. R.

2003-10-01

220

Stability of a rectangular plate under biaxial tension  

NASA Astrophysics Data System (ADS)

The stability problem of a rectangular plate undergoing uniform biaxial in-plane tensile strain is solved using the three-dimensional equations of nonlinear elasticity. The surfaces of the plate are stress-free, and special boundary conditions that allow one to separate variables in the linearized equilibrium equations are specified on the lateral surfaces. For three particular models of incompressible materials, the critical curves are constructed and the instability region is determined in the plane of the loading parameters (the multiplicities of elongations of the plate material in the unperturbed equilibrium state). The numerical results show that for thin plates loaded by tensile stresses, the size and shape of the instability region depend only slightly on the relation among the length, width, and thickness of the plate. Based on the results obtained, a simple approximate stability criterion is proposed for an elastic plate under tensile loads.

Sheidakov, D. N.

2007-07-01

221

Plate Wave Resonance with Air-Coupled Ultrasonics  

NASA Astrophysics Data System (ADS)

Air-coupled ultrasonic transducers can excite plate waves in metals and composites. The coincidence effect, i.e., the wave vector of plate wave coincides with projection of exciting airborne sound vector, leads to a resonance which strongly amplifies the sound transmission through the plate. The resonance depends on the angle of incidence and the frequency. In the present study, the incidence angle for maximum transmission (?max) is measured in plates of steel, aluminum, carbon fiber reinforced composites and honeycomb sandwich panels. The variations of (?max) with plate thickness are compared with theoretical values in steel, aluminum and quasi-isotropic carbon fiber composites. The enhanced transmission of air-coupled ultrasound at oblique incidence can substantially improve the probability of flaw detection in plates and especially in honeycomb structures. Experimental air-coupled ultrasonic scan of subtle flaws in CFRP laminates showed definite improvement of signal-to-noise ratio with oblique incidence at ?max.

Bar, H. N.; Dayal, V.; Barnard, D.; Hsu, D. K.

2010-02-01

222

Plates and FEM  

NASA Astrophysics Data System (ADS)

The word plate is a collective term for systems in which transfer of forces occurs in two directions; walls, deep beams, floors and bridge slabs are all plates. We distinguish two main categories, plates that are loaded in their plane, and plates loaded perpendicularly to their plane. For both categories we give an approach with differential equations, such that a basic understanding is provided and for certain characteristic cases an exact solution can be determined. We follow the displacement method, working with differential equations. In plates that are loaded in their plane, the plane stress state is called the membrane state. All stress components are parallel to the mid- plane of the plate. In special cases we can simply determine the stresses.

Blaauwendraad, J.

223

Drag Measurements of Porous Plate Acoustic Liners  

NASA Technical Reports Server (NTRS)

This paper presents the results of direct drag measurements on a variety of porous plate acoustic liners. The existing literature describes numerous studies of drag on porous walls with injection or suction, but relatively few of drag on porous plates with neither injection nor suction. Furthermore, the porosity of the porous plate in existing studies is much lower than typically used in acoustic liners. In the present work, the acoustic liners consisted of a perforated face sheet covering a bulk acoustic absorber material. Factors that were varied in the experiment were hole diameter, hole pattern, face sheet thickness, bulk material type, and size of the gap (if any) between the face sheet and the absorber material.

Wolter, John D.

2005-01-01

224

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.

2007-12-12

225

Plating methods, a survey  

NASA Technical Reports Server (NTRS)

Results are presented of a comprehensive search of the literature available, much of which has been generated by the research centers of NASA and its contractors, on plating and coating methods and techniques. Methods covered included: (1) electroplating from aqueous solutions; (2) electroplating from nonaqueous solutions; (3) electroplating from fused-salt baths; (4) electroforming; (5) electroless plating, immersion plating, and mirroring; (6) electroplating from gaseous plasmas; and (7) anodized films and conversion coatings.

Berkowitz, J. B.; Emerson, N. H.

1972-01-01

226

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

227

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

228

Spreading continents kick-started plate tectonics.  

PubMed

Stresses acting on cold, thick and negatively buoyant oceanic lithosphere are thought to be crucial to the initiation of subduction and the operation of plate tectonics, which characterizes the present-day geodynamics of the Earth. Because the Earth's interior was hotter in the Archaean eon, the oceanic crust may have been thicker, thereby making the oceanic lithosphere more buoyant than at present, and whether subduction and plate tectonics occurred during this time is ambiguous, both in the geological record and in geodynamic models. Here we show that because the oceanic crust was thick and buoyant, early continents may have produced intra-lithospheric gravitational stresses large enough to drive their gravitational spreading, to initiate subduction at their margins and to trigger episodes of subduction. Our model predicts the co-occurrence of deep to progressively shallower mafic volcanics and arc magmatism within continents in a self-consistent geodynamic framework, explaining the enigmatic multimodal volcanism and tectonic record of Archaean cratons. Moreover, our model predicts a petrological stratification and tectonic structure of the sub-continental lithospheric mantle, two predictions that are consistent with xenolith and seismic studies, respectively, and consistent with the existence of a mid-lithospheric seismic discontinuity. The slow gravitational collapse of early continents could have kick-started transient episodes of plate tectonics until, as the Earth's interior cooled and oceanic lithosphere became heavier, plate tectonics became self-sustaining. PMID:25230662

Rey, Patrice F; Coltice, Nicolas; Flament, Nicolas

2014-09-18

229

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

230

Compton Thick AGN  

NASA Astrophysics Data System (ADS)

Compton thick active galactic nuclei (AGN), which are obscured by column density NH > 1.5 104 cm-2, can be difficult to identify. They are certainly cosmically significant, both in producing the observed cosmic X-ray background, and in providing a location where black hole growth is hidden from view. Here I review some recent results from surveys that provide indications of Compton thick AGN, considering X-ray, radio, and infrared selection techniques. I also offer a caution against using mid-infrared silicate features to measure line-of-sight obscuration to active galactic nuclei. Instead, these features better indicate the geometric distribution of dust that the central engine heats. I conclude that the outstanding problem of Compton thick AGN is not the cases where the obscuration is directly associated with the environment of the active nucleus itself, even in the most obscured examples. Instead, we still risk missing the completely buried AGN, which are obscured by large amounts of gas and dust over large solid angles. The solution to finding Compton thick AGN may be to begin the search based on infrared emission and star formation, and then select for nuclear activity.

Levenson, N. A.

2014-07-01

231

Mechanosensing of substrate thickness  

PubMed Central

Structure and function of the adherent cell depend in a crucial way on its microenvironment, including the stiffness of its substrate. It is often asserted that substrate thickness (as opposed to stiffness) plays a negligible role and therefore may be considered semi-infinite. This assertion has been recently challenged, but the characteristic length scale to consider in this regard is poorly understood. We show here that this characteristic length scale is the lateral cell size. As substrate thickness approaches the lateral dimension of the cell, the apparent stiffness of the substrate is amplified to levels much greater than the intrinsic stiffness of the substrate. This change in apparent stiffness is readily sensed by the cell, leading to changes in cell spreading area, stiffness, and contractile forces. In contrast to these responses that occur over the length of the cell, mechanosensing around an isolated point force is influenced greatly by intrinsic substrate stiffness but to a negligible extent by substrate thickness. We conclude that mechanosensing of substrate thickness is dominated in large part by traction forces spread over the lateral dimension of the cell. PMID:21230324

Lin, Yu-Chun; Tambe, Dhananjay T.; Park, Chan Young; Wasserman, Michael R.; Trepat, Xavier; Krishnan, Ramaswamy; Lenormand, Guillaume; Fredberg, Jeffrey J.; Butler, James P.

2012-01-01

232

Author's personal copy Plate tectonic reconstructions with continuously closing plates$  

E-print Network

Author's personal copy Plate tectonic reconstructions with continuously closing plates$ Michael May 2011 Keywords: Geodynamics Plate tectonics a b s t r a c t We present a new algorithm for modeling margins and plates, traditional global plate tectonic reconstructions have become inadequate

Bower, Dan J.

233

Sensing properties of normal oscillatory modes of quartz plates  

NASA Astrophysics Data System (ADS)

The responses (relative velocity variations ? v/v of normal (symmetric or asymmetric) Lamb and shear-horizontal modes of ST-cut quartz plates, whose thickness is comparable with the wavelength, is studied. Since modes of different orders n belonging to these two families have different propagation velocities v n, polarizations u i, and displacement distributions in depth H, they exhibit different responses to variations in the parameters of the plate (density, elastic moduli, thickness, and temperature) and to the loading of its surface by thin films (i.e., to surface adsorption). Results of numerical calculation of the responses to these parameters are corroborated by experiments on the effect of the plate temperature variation and the effect of adsorption of water vapor onto the plate surface.

Anisimkin, I. V.

2004-03-01

234

Growth of bloodstream and procyclic T. brucei colonies on agarose plates Vern B. Carruthers & Kevin Tan, Laboratory of Molecular Parasitology, Rockefeller University.  

E-print Network

be lifted onto filters and processed according to standard protocols for hybridization with DNA probes. Autoclave 15 min, mix thoroughly and place in a 50 °C water bath. Ingredient 5 plates 10 plates 15 plates 20

Cross, George

235

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, 2011 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,...

2011-07-01

236

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

237

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

238

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

239

Assessment of computational models for thermoelectroelastic multilayered plates  

Microsoft Academic Search

A study is made of the accuracy of the steady-state (static) thermoelectroelastic response of multilayered hybrid composite plates predicted by five modeling approaches, based on two-dimensional plate theories. The plates consist of a combination of fibre-reinforced and piezothermoelastic layers. The standard of comparison is taken to be the exact three-dimensional thermoelectroelastic solutions, and the quantities compared include gross response characteristics

Y. Y. Tangt; A. K. Noor; K. Xu

1996-01-01

240

Effect of Curvature on the Impact Damage Characteristics and Residual Strength of Composite Plates  

NASA Technical Reports Server (NTRS)

The results of a study of the response and failure characteristics of thin, cylindrically curved, composite plates subjected to low-speed impact damage are presented. The results indicate that the plate radius and the plate thickness are important structural parameters that influence the nonlinear response of a plate for a given amount of impact energy. Analytical and experimental contact-force results are compared for several plates and the results correlate well. The impact-energy levels required to cause damage initiation and barely visible impact damage are a function of the plate radius for a given plate thickness. The impact-energy levels required to initiate impact damage for plates with a certain range of radii are greater than plates with other radii. The contact-force results corresponding to these impact-energy levels follow a similar trend. Residual strength results for plates with barely visible impact damage suggest that the compression-after-impact residual strength is also a function of plate radius. The residual strength of impact-damaged flat plates appears to be lower than the residual strength of the corresponding cylindrically curved plates.

Ambur, Damodar R.; Starnes, James H., Jr.

1998-01-01

241

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.

242

The Moving Plates  

NSDL National Science Digital Library

This lesson focuses on relative versus absolute velocity. Students can use a program (must be connected to the internet) to calculate the different types of velocities for different points along plate boundaries. A very brief description of the earth's plates is given, with links to additional information and images. Includes discussion questions.

243

Mapping Plate Boundaries  

NSDL National Science Digital Library

This in-class exercise, profiled on the Starting Point website, is intended to have the students discover plate boundaries based on the uneven geographic occurrence of geologic hazards. The website details the learning goals, teaching notes and materials, and context for this activity. It offers an extensive list of links to additional resources and materials for lecture on geologic hazards and plate tectonics.

Johnson, Rurik

2009-11-12

244

How Do Plates Move?  

NSDL National Science Digital Library

The representation shows the circulation of convection cells in the mantle related to plate movement. A static cross-sectional diagram and accompanying text illustrates the how material heated by the core rises and then sinks when it eventually cools down and attributes this cycle of heating and cooling to tectonic plate movement.

245

Vibration of skewed cantilever plates and helicoidal shells  

NASA Technical Reports Server (NTRS)

Theoretical vibration frequencies and mode shapes are obtained for skewed plates and helicoidal shells with a cantilever boundary. Using Hamilton's law of varying action, a power series solution is developed to obtain converged numerical results for the five lowest frequencies. Effects of geometrical variables such as aspect ratio, sweep angle and shell radius to thickness ratio are investigated. Accuracy of the solution method is substantiated by comparison with existing skewed plate spherical cap, and conical shell results.

Beres, D. P.; Bailey, C. D.

1975-01-01

246

Plate Tectonics Prof. Thomas Herring  

E-print Network

1 Plate Tectonics Prof. Thomas Herring MIT 05/14/02 Lexington HS Plate tectonics 2 Contact/14/02 Lexington HS Plate tectonics 3 Overview · Development of the Plate tectonic theory · Geological Data ­ Sea-floor spreading ­ Fault types from earthquakes ­ Transform faults ­ Today's measurements of plate tectonics 05

Herring, Thomas

247

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

248

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.

249

Thermophoresis of Graphene Plates  

NASA Astrophysics Data System (ADS)

Thermophoresis of graphene plates in an air medium is discussed within the framework of a molecular-kinetic approach. Its rate is found to be independent of the plate area and the aspect ratio of a rectangular graphene. It does depend on the plate orientation in space, which is controlled by the principle of least resistance. The dependence is expressed via a geometrical parameter ?, whose limiting values within the variation interval are found to be 0.46 and 0.65. A solution of the Euler problem on the Brownian rotation of a plate around its center of mass as a result of collisions of molecules in the temperature gradient field allowed us to obtain for the graphene plates a statistical average of ? =0.5. This value turned out to be the same as the one for spherical nanoparticles, for which rotations are irrelevant.

Bubenchikov, A. M.; Bubenchikov, M. A.; Potekaev, A. I.; Maslov, A. S.; Ovcharenko, V. V.; Usenko, O. V.

2014-11-01

250

PLATE TECTONICS USING GIS Understanding plate tectonics using real  

E-print Network

PLATE TECTONICS USING GIS Understanding plate tectonics using real global data sets pertaining OF THE UPSTATE, SC An afternoon field trip to observe the evidences for plate tectonic history, and to witness

251

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 75C. 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 70C and 110C 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

2011-04-01

252

Plate forming and break down pizza box  

DOEpatents

A standard corrugated paper pizza box is provided with slit cuts cut through the top panel of the pizza box in a shape to form four circular serving plates with a beveled raised edge and cross slit cuts through the bottom panel of the pizza box separating the box into four essentially equal portions for easy disposal.

Pantisano, Frank (411 Linda Ave., Blackwood, NJ 08012); Devine, Scott M. (B7 Fairways Apartments, Blackwood, NJ 08012)

1992-01-01

253

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

254

Plating of isolated tobacco mesophyll protoplasts on agar medium  

Microsoft Academic Search

A technique was developed to derive cell and plant clones from isolated mesophyll protoplasts of tobacco. The protoplasts, plated on a fully defined agar medium, divided and grew actively forming visible colonies after one month of culture. Efficiency of colony formation depended on cell density and light condition during incubation. Under standard conditions, 60% of plated protoplasts formed colonies. Upon

Toshiyuki Nagata; Itaru Takebe

1971-01-01

255

A dual polarized near-field focusing plate at microwave frequencies providing sub-wavelength focusing in two dimensions  

Microsoft Academic Search

In this work we introduce a novel near-field focusing plate able to provide sub-wavelength focusing in both directions, parallel to the plate, as well as for both polarizations of the illuminating plane wave at microwave frequencies. Two similar designs are proposed: the first one is made of a thick metallic plate, whereas the second one is made of a thin

S. Ali Hosseini; Salvatore Campione; Filippo Capolino

2011-01-01

256

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

257

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

258

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. PMID:24453601

Mandarano-Filho, Luiz Garcia; Bezuti, Mrcio Takey; Mazzer, Nilton; Barbieri, Cludio Henrique

2012-01-01

259

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

260

Powder metallurgy titanium 6A1-4V plate  

SciTech Connect

A powder metallurgical approach has been combined with controlled mill processing to produce a highly uniform plate material suitable for structural applications. Prealloyed ELI Titanium 6A1-4V powder produced by the rotating electrode process was consolidated into billet by hot isostatic pressing. The resulting billet of uniform composition and random texture was then hot cross-rolled to 3 cm thick plate. Following rolling, the plate was given a beta annealing heat treatment to maximize damage tolerance. The plate was characterized with respect to metallurgical structure, composition, texture, and room temperature mechanical properties. The results of the study show that a powder metallurgy titanium mill product possessing uniform macro- and microstructure is technically feasible and exhibits tensile and fatigue properties equivalent to those of conventionally produced ingot-source wrought plate.

Geisendorfer, R.F.

1980-01-01

261

Power flow analysis of two coupled plates with arbitrary characteristics  

NASA Technical Reports Server (NTRS)

The limitation of keeping two plates identical is removed and the vibrational power input and output are evaluated for different area ratios, plate thickness ratios, and for different values of the structural damping loss factor for the source plate (plate with excitation) and the receiver plate. In performing this parametric analysis, the source plate characteristics are kept constant. The purpose of this parametric analysis is to be able to determine the most critical parameters that influence the flow of vibrational power from the source plate to the receiver plate. In the case of the structural damping parametric analysis, the influence of changes in the source plate damping is also investigated. As was done previously, results obtained from the mobility power flow approach will be compared to results obtained using a statistical energy analysis (SEA) approach. The significance of the power flow results are discussed together with a discussion and a comparison between SEA results and the mobility power flow results. Furthermore, the benefits that can be derived from using the mobility power flow approach, are also examined.

Cuschieri, J. M.

1988-01-01

262

Optimizing material properties of composite plates for sound transmission problem  

NASA Astrophysics Data System (ADS)

To calculate the specific transmission loss (TL) of a composite plate, the conjugate gradient optimization method is utilized to estimate and optimize material properties of the composite plate in this study. For an n-layer composite plate, a nonlinear dynamic stiffness matrix based on the thick plate theory is formulated. To avoid huge computational efforts due to the combination of different composite material plates, a transfer matrix approach is proposed to restrict the dynamic stiffness matrix of the composite plate to a 44 matrix. Moreover, the transfer matrix approach has also been used to simplify the complexity of the objective function gradient for the optimization method. Numerical simulations are performed to validate the present algorithm by comparing the TL of the optimal composite plate with that of the original plate. Small number of iterations required during convergence tests illustrates the efficiency of the optimization method. The results indicate that an excellent estimation for the composite plate can be obtained for the desired sound transmission.

Tsai, Yu-Ting; Pawar, S. J.; Huang, Jin H.

2015-01-01

263

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.

Stuart Snodgrass

2002-03-14

264

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.

265

Mode selection of guided waves for ultrasonic inspection of gas pipelines with thick coating  

Microsoft Academic Search

Mode selection of guided waves in an elastic steel plate with thick coating layer has been studied here. Effect of both thick elastic coating and damping of the coating layer on the dispersion and mode shapes has been investigated and modes that are less affected by elastic coating and damping have been identified. For modeling the viscoelastic behavior of the

E. Pan; J. Rogers; S. K. Datta; A. H. Shah

1999-01-01

266

Optical low coherence reflectometry for the measurement of collagen thickness  

E-print Network

OF FIGURES Figure Figure 1. Power Limitation on Incident Light in the Eye 2. Measurement of Corneal Thickness by LDI. '. Page 13 Figure 3. Standard Michelson Interferometer. " Figure 4 One Dimensional View of the Michelson Interferometer... primarily in the eye. The major applications of OLCR are to measure corneal thickness and axial eye length. ~'" The cornea-curvature radius can also be examined. ' OLCR can be used to measure the anterior chamber thickness. This measurement helps...

Merchant, Jean Carol

2012-06-07

267

Correlations between force plate measures for assessment of balance  

Microsoft Academic Search

Objective. To compare different force plate measures for assessment of postural stability during normal standing. Five types of measures were analysed: (1) The standard deviation of the horizontal ground reaction force, (2) the standard deviation of the centre of pressure, (3) the mean velocity of the centre of pressure, (4) movement strategy measures, and (5) the standard deviation of the

Annica Karlsson; Gunilla Frykberg

2000-01-01

268

49 CFR 230.26 - Tensile strength of shell plates.  

Code of Federal Regulations, 2010 CFR

...DEPARTMENT OF TRANSPORTATION STEAM LOCOMOTIVE INSPECTION AND MAINTENANCE STANDARDS Boilers and Appurtenances Strength of Materials 230.26 Tensile strength of shell plates. When the tensile strength of steel or wrought-iron shell...

2010-10-01

269

Plate flexure and mechanics: Observational constraints  

NASA Astrophysics Data System (ADS)

Plate flexure is a phenomenon that describes how the lithosphere responds to long-term (>10^5 a) geological loads. By comparing the flexure in the vicinity of ice, volcano, and sediment loads to predictions based on simple plate models it has been possible to estimate the effective elastic thickness of the lithosphere, T_e. In the oceans, T_e is the range 2-50 km and is determined mainly by plate and load age. The continents, in contrast, are characterised by T_e values of up to 80 km and greater. Rheological considerations based on data from experimental rock mechanics suggest that T_e reflects the integrated brittle, elastic and ductile strength of the lithosphere. T_e differs, therefore, from the seismogenic layer thickness, T_s, which indicates the depth to which faulting extends in the uppermost brittle layer. Despite differences in their time-scales, T_e and T_s are similar in the oceans where loading reduces the initial mechanical thickness to a thickness that coincides with that of the brittle layer. They differ, however, in continents, which unlike oceans, are characterized by a multi-layer rheology. As a result, T_e >> T_s in cratons, many convergent zones, and some rifts. Most rifts, however, are characterized by low T_e which has been variously attributed to a young thermal age of the rifted lithosphere, thinning and heating at the time of rifting, and yielding due to post-rift sediment loading. Irrespective of their origin, the Wilson Cycle makes it likely that low values will be inherited by some foreland basins which, in turn, helps explain why similarities between T_e and T_s extend beyond rifts into other tectonic regions such as orogenic belts and, occasionally, the cratons themselves.

Watts, A. B.; Burov, E. B.

2003-04-01

270

Experimental Structural Dynamic Response of Plate Specimens Due to Sonic Loads in a Progressive Wave Tube  

NASA Technical Reports Server (NTRS)

The objective of the current study was to assess the repeatability of experiments at NASA Langley's Thermal Acoustic Fatigue Apparatus (TAFA) facility and to use these experiments to validate numerical models. Experiments show that power spectral density (PSD) curves were repeatable except at the resonant frequencies, which tended to vary between 5 Hz to 15 Hz. Results show that the thinner specimen had more variability in the resonant frequency location than the thicker sample, especially for modes higher than the first mode in the frequency range. Root Mean Square (RMS) tended to be more repeatable. The RMS behaved linearly through the SPL range of 135 to 153 dB. Standard Deviations (STDs) of the results tended to be relatively low constant up to about 147 dB. The RMS results were more repeatable than the PDS results. The STD results were less than 10% of the RMS results for both the 0.125 in (0.318 cm) and 0.062 in (0.1588 cm) thick plate. The STD of the PSD results were around 20% to 100% of the mean PSD results for non-resonant and resonant frequencies, respectively, for the 0.125 in (0.318 cm) thicker plate and between 25% to 125% of the mean PSD results, for nonresonant and resonant frequencies, respectively, for the thinner plate.

Betts, Juan F.

2001-01-01

271

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 waves 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

272

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 waves 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

273

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

274

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

275

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

276

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

277

Fabrication of a micro-hole array on metal foil by nanosecond pulsed laser beam machining using a cover plate  

NASA Astrophysics Data System (ADS)

A novel laser beam machining (LBM) method is proposed to achieve higher precision and better quality beyond the limits of a commercialized nanosecond pulsed laser system. The use of a cover plate is found to be effective for the precision machining of a thin metal foil at micro scale. For verifying the capability of cover plate laser beam machining (c-LBM) technology, a 30 by 30 array of micro-holes was fabricated on 8?m-thick stainless steel 304 (STS) foil. As a result, thermal deformation and cracks were significantly reduced in comparison with the results using LBM without a cover plate. The standard deviation of the inscribed and circumscribed circle of the holes with a diameter of 12?m was reduced to 33% and 81%, respectively and the average roundness improved by 77%. Moreover, the smallest diameter obtainable by c-LBM in the given equipment was found to be 6.9?m, which was 60% less than the minimum size hole by LBM without a cover plate.

Ha, Kyoung Ho; Lee, Se Won; Kim, Janggil; Jee, Won Young; Chu, Chong Nam

2015-02-01

278

Plate Rolling Modeling at Mill 5000 of OJSC ``Magnitogorsk Iron and Steel'' for Analysis and Optimization of Temperature Rates  

NASA Astrophysics Data System (ADS)

Modeling of strip deflected mode and thermal state in rolling is an integral part of the technology and perspective rolling-mill machinery such as plate mill 5000 of the OJSC "Magnitogorsk Iron and Steel". To comprehend metal behavior in the deformation zone in the rough passes during plate rolling it is essential to assess the impact of various temperature factors on variations in field of stress and strain intensities as well as temperature fields in deformation. To do such researches in consideration of various software products and adequate results one of the most effective methods nowadays is regarded as the method of finite elements. The research shows modeling of roughing rolling of a pipe steel sheet with strength category X80 according to standard API-5L. In the research of the metal deflected mode software product DEFORM 2D has been used for the isothermal and nonisothermic process. The mathematical modeling allows revealing the impact of temperature field on the metal deflected mode in the rough passes in plate rolling. Supposedly, it is deformation heating that can have more impact on the ingot temperature profile in the finishing passes in controlled rolling of the pipe steel grades. It is defined by high percent reduction, rolling speeds; more area of heat exchange surface; less thickness and lower temperature of rolling. The results can be used to develop efficient modes of plate rolling of the pipe steels.

Salganik, V.; Shmakov, A.; Pesin, A.; Pustovoytov, D.

2010-06-01

279

Plate Tectonics: An Introduction  

NSDL National Science Digital Library

In the early 1900s, most geologists thought that Earth's appearance, including the arrangement of the continents, had changed little since its formation. This video segment describes the impact the theory of plate tectonics has had on our understanding of Earth's geological history, and provides a brief overview of what is currently known about the Earth's tectonic plates and their motions. The segment is two minutes twenty-one seconds in length. A background essay and list of discussion questions are also provided.

280

Fractal multifiber microchannel plates  

NASA Technical Reports Server (NTRS)

The construction and performance of microchannel plates (MCPs) made using fractal tiling mehtods are reviewed. MCPs with 40 mm active areas having near-perfect channel ordering were produced. These plates demonstrated electrical performance characteristics equivalent to conventionally constructed MCPs. These apparently are the first MCPs which have a sufficiently high degree of order to permit single channel addressability. Potential applications for these devices and the prospects for further development are discussed.

Cook, Lee M.; Feller, W. B.; Kenter, Almus T.; Chappell, Jon H.

1992-01-01

281

How Plates Move  

NSDL National Science Digital Library

This information on the two major types of plate interaction and the resulting features discusses the Mid Atlantic Ridge and the mid-ocean ridges in connection with divergence and ocean trenches and connects the Pacific Ring of Fire to the concept of subduction. Volcanic activity as a result of subduction is also covered. The site also features links to goals, objectives, and materials for a hands-on lesson on how plates move.

282

Free vibrations of thermally stressed orthotropic plates with various boundary conditions  

NASA Technical Reports Server (NTRS)

An analytical investigation of the vibrations of thermally stressed orthotropic plates in the prebuckled region is presented. The investigation covers the broad class of trapezoidal plates with two opposite sides parallel. Each edge of the plate may be subjected to different uniform boundary conditions. variable thickness and arbitrary temperature distributions (analytical or experimental) for any desired combination of boundary conditions may be prescribed. Results obtained using this analysis are compared to experimental results obtained for isotropic plates with thermal stress, and to results contained in the literature for orthotropic plates without thermal stress. Good agreement exists for both sets of comparisons.

Bailey, C. D.; Greetham, J. C.

1973-01-01

283

Measurement of Thin Oil Film Thickness Using Ultrasonic Technique  

NASA Astrophysics Data System (ADS)

An application of ultrasonic technique is attempted for the purpose of measuring thin oil film thickness between two surfaces. The amplitude of the wave reflected from the boundary is vary depending on film thickness, because the ultrasonic wave emitted to the interface between two surfaces does multiple reflection and interference in oil film. Quantitative measurement of oil film thickness then can be possible. For instance, it is possible to measure the submicron film thickness which exists near the point contact formed by convex glass and plate with high frequency probe. And it is confirmed that the oil film thickness estimated from the echo height agrees with the film thickness decided by the curvature of the lens or obtained by the optical interference method, even if it is 100 nm. On the other hand, the thickness of oil film between cylinder and piston ring can be easily measured by setting the small ultrasonic probe on the back of piston ring. For example, the influence of the second ring and oil ring for the behavior of an oil film formed on a top ring is able to evaluate quantitatively. As mentioned above, it is cleared that quantitative evaluation of thin film thickness is possible with investigating the echo height obtained by ultrasonic wave pulse reflection method.

Takeuchi, Akitoshi; Terada, Seiichi; Toda, So

284

Magnetic and microwave absorbing properties of CoFe thin films plated on hollow ceramic microspheres of low density  

Microsoft Academic Search

Conductive and magnetic microspheres are fabricated by plating of CoFe alloy thin films on hollow ceramic microspheres of low density for the application to lightweight microwave absorbers. Metal plating was carried out in a two-step electroless plating process (pre-treatment of sensitizing and subsequent plating). Uniform coating of the film with about 2?m thickness was identified by SEM. High-frequency magnetic and

Sung-Soo Kim; Seon-Tae Kim; Joon-Mo Ahn; Keun-Hong Kim

2004-01-01

285

A database of worldwide glacier thickness observations  

NASA Astrophysics Data System (ADS)

One of the grand challenges in glacier research is to assess the total ice volume and its global distribution. Over the past few decades the compilation of a world glacier inventory has been well-advanced both in institutional set-up and in spatial coverage. The inventory is restricted to glacier surface observations. However, although thickness has been observed on many glaciers and ice caps around the globe, it has not yet been published in the shape of a readily available database. Here, we present a standardized database of glacier thickness observations compiled by an extensive literature review and from airborne data extracted from NASA's Operation IceBridge. This database contains ice thickness observations from roughly 1100 glaciers and ice caps including 550 glacier-wide estimates and 750,000 point observations. A comparison of these observational ice thicknesses with results from area- and slope-dependent approaches reveals large deviations both from the observations and between different estimation approaches. For glaciers and ice caps all estimation approaches show a tendency to overestimation. For glaciers the median relative absolute deviation lies around 30% when analyzing the different estimation approaches. This initial database of glacier and ice caps thickness will hopefully be further enlarged and intensively used for a better understanding of the global glacier ice volume and its distribution.

Grtner-Roer, I.; Naegeli, K.; Huss, M.; Knecht, T.; Machguth, H.; Zemp, M.

2014-11-01

286

Modeling of composite beams and plates for static and dynamic analysis  

NASA Technical Reports Server (NTRS)

A rigorous theory and the corresponding computational algorithms were developed for through-the-thickness analysis of composite plates. This type of analysis is needed in order to find the elastic stiffness constants of a plate. Additionally, the analysis is used to post-process the resulting plate solution in order to find approximate three-dimensional displacement, strain, and stress distributions throughout the plate. It was decided that the variational-asymptotical method (VAM) would serve as a suitable framework in which to solve these types of problems. Work during this reporting period has progressed along two lines: (1) further evaluation of neo-classical plate theory (NCPT) as applied to shear-coupled laminates; and (2) continued modeling of plates with nonuniform thickness.

Hodges, Dewey H.

1992-01-01

287

Vibrational analysis of rectangular sandwich plates resting on some elastic point supports  

SciTech Connect

An approximate solution of forced-vibration for rectangular sandwich plate resting on some elastic point supports is presented. The sandwich plate has thin, anisotropic composite laminated faces and a thick orthotropic core. The simplified sandwich plate model is used in the analysis. The governing equation of elastically point supported rectangular sandwich plate is obtained by using the Lagrange equation. The steady state response solution to a sinusoidally varying point force is also derived. The response curves of rectangular sandwich plates having CFRP laminated faces and aluminum honeycomb core is calculated. Application examples illustrate the effects of laminate lay-up of face sheets, core material properties and core thickness ratio on the vibration characteristics of rectangular sandwich plate.

Ichinomiya, Osamu; Maruyama, Koichi; Sekine, Kouji [Hokkaido Inst. of Tech., Sapporo (Japan). Dept. of Mechanical engineering

1995-11-01

288

Scintillating plate calorimeter mechanical design  

Microsoft Academic Search

Progress on designs for compensating scintillator plate calorimeters will be presented. One design includes a lead composite absorber, fiber readout, and radiation hardened scintillator plates, and the second design has depleted uranium absorbers, wave length shifter plate readout, and scintillator plates. The lead absorber is cast with slots to accept the scintillator in the first design, while the depleted uranium

A. Buehring; N. Hill; T. Kirk; J. Nasiatka; E. Petereit; L. Price; J. Proudfoot; H. Spinka; D. Underwood; M. Burke; D. Hackworth; T. Hordubay; D. Marshik; D. Scherbarth; R. Swensrud

1990-01-01

289

An Introduction to Plate Tectonics  

NSDL National Science Digital Library

This page is a brief introduction to plate tectonics. It starts with a discussion of the evolution of the theory of plate tectonics and the arguments supporting it. It then discusses the processes associated with tectonics and the types of plate boundaries: divergent, convergent and transform boundaries. It concludes with a discussion of the current hypotheses of what causes plates to move.

290

India Plate Motion, Intraplate deformation and Plate Boundary Processes (Invited)  

NASA Astrophysics Data System (ADS)

We use GPS-measured velocities to geodetically constrain India plate motion, intraplate strain, and examine plate boundary deformation and plate interactions around the India plate. Our solution includes 15 GPS velocities from continuously recording stations from within the stable India plate interior that are used to estimate angular velocity of the India plate with respect to its neighbors. We test a two-plate India system divided along the topographically prominent Narmada Son Lineament and find this scenario to be significant only to 89%. Dense station coverage along the Himalayan range front allows us to rigorously test boundary parameterizations and develop a preferred plate boundary model. In our preferred model the Himalayan Range Front accumulates ~50% of the India-Eurasia convergence with as much as 18 mm/yr of slip accumulation along some segments. We compare earthquake slip vector orientations with predicted divergence directions from our preferred model along the India-Somalia plate boundary. We see good agreement between predicted plate directions from our preferred model and the seismological data. Deviations between our model and the slip vectors highlight areas of diffuse oceanic deformation along the plate boundary. We estimate convergence vectors for the relative plate pairs along the Sumatra subduction zone. We test for the transition between Australian plate convergence and India plate convergence along the Sumatra subduction zone and refine the estimated motion of the Burman sliver plate.

Apel, E. V.; Burgmann, R.; Banerjee, P.

2010-12-01

291

Caribbean plate interactions  

SciTech Connect

Vector analysis of plate motions, derived from studies of Atlantic magnetic lineations and fracture zone trends, indicates the following relative movements between the Caribbean, North American, and South American Plates. (1) During Early Jurassic to Early Cretaceous, the North American Plate moved 1900 km westward and 900 km northward relative to the South American Plate. A broad zone including the Caribbean region, i.e., the zone between the North and South America Plates, was a site of left-lateral shear and north-south extension. (2) During Early Cretaceous to Late Cretaceous, the North American Mate moved an additional 1200 km westward relative to South America across this zone. (3) During Late Cretaceous to the end of the Eocene, the North American Plate moved 200 km westward and 400 km northward relative to the South American Plate. (4) From the end of the Eocene to near the end of the Miocene, North America converged on South America some 200 km and moved 100 km eastward relative to it. Through the Mesozoic and earliest Tertiary history of the Caribbean, the region was a shear zone within which left-lateral displacement exceeded 3000 km and north-south extension exceeded 1300 km. In regard to time, 80% of the history of the Caribbean region is one of north-south extension and left-lateral shear. In terms of space, 97% of the shear is left-lateral and the ratio of divergence versus convergence is 7 to 1. Thus, characterizing the Caribbean region, and the Atlantic to its east, as a zone of north-south extension and left-lateral shear, is a fair generalization.

Ball, M. (Geological Survey, Denver, CO (United States))

1993-02-01

292

Redesign of Indonesian-made osteosynthesis plates to enhance their mechanical behavior.  

PubMed

Mechanical properties determined by fatigue strength, ductility, and toughness are important measures for osteosynthesis plates in order to tolerate some load-bearing situations caused by muscle contractions and weight-bearing effects. Previous study indicated that Indonesian-made plates showed lower mechanical strength compared to the European AO standard plate. High stress under load-bearing situations often starts from surface of the plate; we therefore refined the grain size of the surface by using shot peening and surface mechanical attrition treatment (SMAT). Single cycle bending tests showed that shot-peened and SMAT-treated plates had significantly higher load limit and bending stress compared to the original plates (p<0.05). Weibull analysis confirmed the improvement of proportional load limit of SMAT-treated plates. Fatigue limit also increased upon shot-peening and SMAT treatment (improvement ratio 18% and 27%, respectively). Significant improvement ratio of fatigue tests can be observed in SMAT-treated plates compared to the untreated and shot-peened plates. Fatigue performance demonstrated equivalent results between SMAT-treated and standard plate. These designated that mechanical properties of Indonesian-made plates can be improved upon SMAT treatment leading to significant enhancement of mechanical strength thus is comparable to the standard plate. Our findings highlight the benefits of SMAT treatment to improve mechanical strength of Indonesian-made osteosynthesis plates. PMID:25523978

Dewo, P; van der Houwen, E B; Suyitno; Marius, R; Magetsari, R; Verkerke, G J

2015-02-01

293

HETEROTROPHIC PLATE COUNT BACTERIA IN POTABLE WATER: MONITORING METHODS AND APPLICATION  

EPA Science Inventory

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

294

Response of a slotted plate flow meter to horizontal two phase flow  

E-print Network

meter is always better in performance and accuracy than the standard orifice plate flow meter. This study is primarily based on how a slotted plate responds to horizontal two-phase flow with air and water being used as the working fluids. The plates...

Muralidharan, Vasanth

2005-02-17

295

BEPLATE emdash simulation of electrochemical plating  

SciTech Connect

BEPLATE is a FORTRAN code that uses the boundary element method to simulate the electrochemical plating of material on parts, primarily rotating axisymmetric parts. A boundary element technique is used to solve for the local current density and thus the plating rate on the part, which is used to calculate the growth in the plated layer over a user-specified time step. The surface is moved to reflect this growth, and the new surface is used to generate the local current density. This cycle is repeated until the final time specified by the analyst, producing the final plated thickness. BEPLATE includes models for the polarization effects at both the part (cathode) and anode and allows the use of symmetry planes and nonconducting shields. For electroplating simulations, the part shape is normally assumed to be axisymmetric with a centerline along the z-axis. More general part shapes can be analyzed by BEPLATE if the surface growth simulation is not needed. In either case, the shield, anode, and tank geometries are not restricted to specific shapes. This report includes the information required to run BEPLATE, specifically, a brief description of the BEPLATE system including hardware and software requirements, a description of the complete simulation process, discussion of rules for generating models, and additional reference material. This system of codes consists of model generators (PIGS or PATRAN), input processor (BEPIN), the simulation code (BEPLATE) and postprocessing codes (PATRAN or CONPLOT).

Giles, G.E. (Oak Ridge K-25 Site, TN (USA)); Gray, L.J. (Oak Ridge National Lab., TN (USA)); Bullock, J.S. IV (Oak Ridge Y-12 Plant, TN (USA))

1990-09-01

296

Dynamic characterization of a laminated composite magnetorheological fluid sandwich plate  

NASA Astrophysics Data System (ADS)

This study investigates the dynamic properties of a laminated composite magnetorheological (MR) fluid sandwich plate. The governing differential equations of motion of a sandwich plate embedding a MR fluid layer as the core layer and laminated composite plates as the face layers are presented in a finite element formulation. The validity of the developed finite element formulation is demonstrated by comparing the results in terms of the natural frequencies derived from the present finite element formulation with those in the available literature. Various parametric studies are also performed to investigate the effect of a magnetic field on the variation of the natural frequencies and loss factors of the MR fluid composite sandwich plate under various boundary conditions. Furthermore, the effect of the thickness of the MR fluid layer and the ply orientation of the composite face layers on the variation of the natural frequencies and loss factors are studied. The free vibration mode shapes under various boundary conditions of a MR fluid laminated composite sandwich plate are also presented. The forced vibration response of a MR fluid composite plate is investigated to study the dynamic response of the sandwich plate under harmonic force excitations in various magnetic fields. The study suggests that the natural frequency increases with increasing magnetic field, irrespective of the boundary conditions. The reduction in peak deflection at each mode under a harmonic excitation force with variation of the applied magnetic field shows the effectiveness of the MR fluid layer in reducing the vibration amplitude of the composite sandwich plate.

Manoharan, R.; Vasudevan, R.; Jeevanantham, A. K.

2014-02-01

297

Dual passband dichroic plate for X-band  

NASA Technical Reports Server (NTRS)

A need arose in the Deep Space Network for a dichroic plate that would simultaneously pass two desired frequency bands in the X-band region. In addition, the plate must be totally reflective for S-band frequencies. A dielectrically loaded dichroic plate is described that was developed to meet this need. The unique microwave properties that the new dichroic plate had to possess were: (1) insertion losses of less than 0.04 dB for X-band uplink frequencies centered at 7167 MHz and for X-band downlink frequencies centered at about 8425 MHz; (2) insertion losses that met the low loss requirements at 30 deg incidence angle simultaneously for both parallel and perpendicular polarizations; (3) total reflectivity at S-band frequencies; and (4) ability to maintain these electrical characteristics while passing 100 kW of CW power at X-band or while reflecting 100 kW of CW power at S-band. The dual passband dichroic plate is a thick metallic plate having an array of periodic round holes filled with Teflon plugs. Test results on an experimental prototype plate indicate that it is technically possible to design a dielectrically filled dichroic plate that meets all of the technical requirements.

Otoshi, T. Y.; Franco, M. M.

1988-01-01

298

Surface Potential of Insulating Plate Coated by Metallic Paint Spray  

Microsoft Academic Search

Surface potential of insulating plate coated by metallic paint spray has been investigated for improving coating system using an air spray gun. The metallic paint contained aluminum flakes with a thickness of about 30 nm in organic solvent. The paint was sprayed on a test target by the air spray gun at a pressure of 0.2 MPa. The target was

Toshiyuki Sugimoto; Noriyuki Shirahata; Yoshio Higashiyama; Koichi Takeda

2007-01-01

299

Characterization of a texture gradient in tantalum plate  

SciTech Connect

Clark et al. have shown that significant texture gradients can be produced in rolled tantalum plate and that the strength of the gradient is dependent on the processing path. Texture gradients are often ignored because they are time consuming to characterize and add significant complexity to materials modeling. The variation in texture through the thickness of rolled materials is most commonly measured by sectioning samples to different depths through the thickness of the plate and then measuring the texture from these section planes by X-ray diffraction. A new technique based on automatic indexing of electron backscatter diffraction patterns in the scanning electron microscope enables spatially specific orientations to be measured in a practical manner. This technique allows spatial variations in texture to be measured directly enabling gradients in texture to be investigated in more detail than previously possible. This data can be used directly in coupled finite-element/polycrystal-plasticity models to simulate the effects of variations in texture on the plastic behavior of polycrystals. This work examines the variation in texture through the thickness of a tantalum plate and its resultant effect on the compressive deformation of samples prepared from the plate. The characterization of the texture gradient using the automatic point-by-point measurement technique mentioned above is described in detail. The effect of the gradient on the plastic response of through-thickness compression tests is also discussed.

Wright, S.I.; Gray, G.T. III

1994-11-01

300

Increasing the impact fatigue strength of ring valve plates  

Microsoft Academic Search

The authors have made an investigation with the object of selecting the optimum shot treatment conditions for ring valve plates. The investigations were conducted on testpieces of grade 30Kh13 steel of length 60 mm, width 10 mm, and thickness 3 mm. These were heat treated as follows: hardening at a temperature of 10301050~ with cooling in oil, tempering at a

V. A. Pyshkin; V. A. Yakovlev; V. Yu. Kuznetsov; S. A. Abramenko

1976-01-01

301

Liquid film thickness measurement by two-line TDLAS  

SciTech Connect

A fiber-based two-line tunable diode-laser absorption sensor with two near-infrared (NIR) distributed-feedback (DFB) diode lasers at ?1.4 ?m was used for non-intrusive time-resolved liquid water film thickness measurement. When probing the liquid film at two different wavelengths with significantly different absorption cross-sections, the additional signal losses due to surface fowling, reflection and beam steering can be eliminated. In this work, the evaporation process of a liquid film on transparent quartz plate was tracked and large fluctuations of film thickness were found at the end of the evaporation.

Yang, Huinan [School of Energy and Power Engineering, University of Shanghai for Science and Technology, 200093, Shanghai, China and IVG, University of Duisburg-Essen, 47057, Duisburg (Germany); Chen, Jun; Cai, Xiaoshu [School of Energy and Power Engineering, University of Shanghai for Science and Technology, 200093, Shanghai (China); Greszik, Daniel; Dreier, Thomas; Schulz, Christof [IVG, University of Duisburg-Essen, 47057, Duisburg (Germany)

2014-04-11

302

Piezoelectric control of composite plate vibration: Effect of electric potential distribution  

Microsoft Academic Search

The paper deals with the vibration analysis of active rectangular plates. The plates considered are composites containing piezoelectric sensor\\/actuator layers, which operate in a velocity feedback control to achieve transverse vibration suppression. The piezoelectric layers are poled through the thickness and equipped with traditional surface electrodes. In order to satisfy the Maxwell electrostatics equation the widely used simplification of the

Marek Pietrzakowski

2008-01-01

303

Improved design procedure for embedded plates in gravity anchors for precast concrete panels  

E-print Network

, in terms of load and principal normal stress, to the physical dimensions and material strength of the plate. That is, P/S = f(t, a~bgE) (4. 1) where P is the applied normal load, S is the largest principal normal stress, t is the plate thickness, a...

Fragomeli, Lawrence Fred

2012-06-07

304

The Finite Element Analysis of Quartz Crystal Resonators with Nonlinear Plate Equations  

E-print Network

The Finite Element Analysis of Quartz Crystal Resonators with Nonlinear Plate Equations Ji Wang1, dujianke, wanglihong}@nbu.edu.cn, yyong@rci.rutgers.edu Abstract--The finite element analysis of quartz for typical thickness-shear vibrations of quartz crystal plates. While linear finite element analysis

Wang, Ji

305

Finite-Element Investigation and Design Recommendations for Perforated Steel Plate Shear Walls  

E-print Network

however the two models are in a good agreement. Based on the analytical results design recommendations of these perforated SPSWs are presented. The shear strength of a SPSW infill plate having a pattern of multiple. However, in some SPSW applications, the minimum available thickness of infill plate might be thicker

Bruneau, Michel

306

The ballistic properties of tool steel as a potential improvised armour plate  

Microsoft Academic Search

The ballistic behaviour of a 0.95 weight per cent carbon tool steel against 7.62 mm ball and armour piercing bullets was investigated in the unwelded and welded condition. Gross cracking occurred at plate hardnesses of 510 HV and greater. The mode of perforation for tool steel of hardness 380 H V, which was petalling for 5 mm thick plates and

M. R. Edwards; A. Mathewson

1997-01-01

307

A study on the failure of circular plates struck by masses. Part 1: experimental results  

Microsoft Academic Search

In the present study experimental results recorded from a series of tests are presented, which examine the dynamic response and petalling failure of thin circular plates struck transversely at the centre by masses having conical heads and spherical noses. The circular plates are cut from mild steel plates with five different thicknesses of 1.17, 1.5, 2, 3 and 4mm and

W. Q. Shen; N. O. Rieve; B. Baharun

2002-01-01

308

On crack susceptibility in the submerged arc welding of medium-carbon steel plates  

Microsoft Academic Search

The present paper describes cracking behaviour during the submerged arc welding of medium carbon steel plates (0.45% C). It discusses the results of tests made to examine the effect of welding variables (current, welding speed and wire feed rate), plate fabrication conditions (rolling reduction ratio) and plate thickness on cracking susceptibility using trans-varestraint tests.It is found that the cracking susceptibility

M. E. Khallaf; M. A. Ibrahim; N. A. El-Mahallawy; M. A. Taha

1997-01-01

309

Tectonic Plates, Earthquakes, and Volcanoes  

NSDL National Science Digital Library

According to theory of plate tectonics, Earth is an active planet -- its surface is composed of many individual plates that move and interact, constantly changing and reshaping Earth's outer layer. Volcanoes and earthquakes both result from the movement of tectonic plates. This interactive feature shows the relationship between earthquakes and volcanoes and the boundaries of tectonic plates. By clicking on a map, viewers can superimpose the locations of plate boundaries, volcanoes and earthquakes.

310

Stress Concentration Around an Open Circular Hole in a Plate Subjected to Bending Normal to the Plane of the Plate  

NASA Technical Reports Server (NTRS)

An aluminum-alloy plate containing an open circular hole of diameter large compared with the thickness of the plate was subjected to bending forces normal to the plane of the plate. Deflection and strain measurements were taken for two different loads. Stress concentrations occurred at the edge of the hole and the maximum stresses were tangential to the hole at the ends of the transverse diameter. The maximum stress at the edge of the hole was 1.59 times the computed stress on the net section and 1.85 times the computed stress in a solid plate of the same dimensions subjected to the same bending forces. The maximum deflections were about 20 percent greater than the corresponding deflection for a solid plate of the same size subjected to the same bending forces. The smallest edge distance was equal to 2-1/2 times the diameter of the hole and the stress concentration on this side of the hole was the same as on the side where the edge distance was about 4-1/2 diameters. A theoretical analysis of the problem shows that, for an aluminum plate of infinite width, the stress concentration at the edge of the hole would be 1.87 times the stress in a solid plate, which is substantially the same relation obtained for the plate tested.

Dumont, C

1939-01-01

311

Dynamic responses of Reissner--Mindlin plates with free edges resting on tensionless elastic foundations  

NASA Astrophysics Data System (ADS)

Dynamic response analysis is presented for a Reissner-Mindlin plate with four free edges resting on a tensionless elastic foundation of the Winkler-type and Pasternak-type. The mechanical loads consist of transverse partially distributed impulsive loads and in-plane static edge loads while the temperature field is assumed to exhibit a linear variation through the thickness of the plate. The material properties are assumed to be independent of temperature. The two cases of initially compressed plates and of initially heated plates are considered. The formulations are based on Reissner-Mindlin first-order shear deformation plate theory and include the plate-foundation interaction and thermal effects. A set of admissible functions is developed for the dynamic response analysis of moderately thick plates with four free edges. The Galerkin method, the Gauss-Legendre quadrature procedure and the Runge-Kutta technique are employed in conjunction with this set of admissible functions to determine the deflection-time and bending moment-time curves, as well as shape mode curves. An iterative scheme is developed to obtain numerical results without using any assumption on the shape of the contact region. The numerical illustrations concern moderately thick plates with four free edges resting on tensionless elastic foundations of the Winkler-type and Pasternak-type, from which results for conventional elastic foundations are obtained as comparators. The results confirm that the plate will have stronger dynamic behavior than its counterpart when it is supported by a tensionless elastic foundation.

Yu, L.; Shen, Hui-Shen; Huo, X.-P.

2007-01-01

312

Predicting gravity and sediment thickness in Afghanistan  

NASA Astrophysics Data System (ADS)

The US Naval Research Laboratory conducted comprehensive high-altitude (7 km above mean sea level) aero-geophysical surveys over Afghanistan in 2006 (Rampant Lion I). The surveys were done in collaboration with the US Geological Survey and upon the request of Islamic Republic of Afghanistan Ministry of Mines. In this study, we show that a best fitting admittance between topography and airborne gravity in western Afghanistan can be used to predict airborne gravity for the no-data area of eastern Afghanistan where the mountains are too high to conduct airborne surveys, due to the threat of ground fire. The differences between the airborne and the predicted gravity along a tie-track through the no-data area were found to be within 12 mGal range with rms difference 7.3 mGal, while those between the predicted gravity from a simple Airy model (with compensation depth of 32 km and crustal density of 2.67 g cm-3) and the airborne gravity were within 22 mGal range with rms difference 10.3 mGal. A combined airborne free-air anomaly has been constructed by merging the predicted gravity with the airborne data. We also demonstrate that sediment thickness can be estimated for basin areas where surface topography and airborne free-air anomaly profiles do not show a correlation presumably because of thick sediments. In order to estimate sediment thickness, we first determine a simple linear relationship from a scatter plot of the airborne gravity points and the interpolated Shuttle Radar Topography Mission (SRTM) topography along the Rampant Lion I tracks, and computed corresponding quasi-topography tracks by multiplying the linear relationship with the airborne free-air anomalies. We then take the differences between the SRTM and quasi-topography as a first-order estimate of sediment thickness. A global gravity model (GOCO02S), upward continued to the same altitude (7 km above mean sea level) as the data collection, was compared with the low-pass filtered (with cutoff wavelength 132 km which is approximately equivalent to the reported safe degree and order 250 of GOCO02S at 34 N) combined airborne free-air anomalies. The rms difference between the two data sets was 12.4 mGal. The observed admittance in the western Afghanistan mountains appears to be best fit to a theoretical elastic plate compensation model (with an effective elastic thickness of 5 km and crustal thickness of 22 km) where the ratio between surface load and subsurface load is equal.

Jung, W.; Brozena, J.; Peters, M.

2013-02-01

313

Thickness distribution of superplastic formed titanium-based domes  

NASA Astrophysics Data System (ADS)

Superplastic forming is an appealing and affordable technique for manufacturing titanium-based structural parts. In this work, circular samples with uniform initial thickness were formed superplastically using finite element modeling (FEM) and the formed domes are analyzed to investigate their thickness distributions. The results indicate that the dome thickness is not uniform and decreases from the apex to the periphery for each formed dome. The increase of the formed dome height results in the increased thinning of the samples, and the increase of the ratio between the thickness at the dome apex and that at the dome periphery. The predicted thickness distribution based on the Enikeev and Kruglov (E-K) model has a good agreement with the FEM result for the formed domes with a large apex height, while it deviates from the FEM result for the formed domes with a small apex height. A possible reason is the neglecting of the body force from the sample weight in the analytical E-K model. The obtained knowledge will help guide the initial thickness design for the plate samples to realize the expected final thickness distributions.

Li, Qizhen

2010-05-01

314

Discovering Plate Boundaries  

NSDL National Science Digital Library

???d?ersity's Earth Science Department offers the Discovering Plate Boundaries educational activity. The exercise is described as a data rich exercise to help students discover the processes that occur at plate tectonic boundaries and has been used successfully with 5th graders to undergraduates. The site provides the necessary downloads of maps; earthquake, volcanic, seafloor, topographic, and bathymetric data; and teacher guides and complete instructions. Because the activity can be geared towards such a large range of students, is well designed, and is easily accessible, educators will definitely appreciate the site.

2007-12-12

315

Plate Tectonics and Volcanism  

NSDL National Science Digital Library

This is a lesson where learners explore plate movement and the relationship between plate tectonics and volcanoes. The lesson models scientific inquiry using the 5E instructional model and includes teacher notes, prerequisite concepts, common misconceptions, student journal and reading. This is lesson five in the Astro-Venture Geology Training Unit that was developed to increase students' awareness of and interest in astrobiology and the many career opportunities that utilize science, math and technology skills. The lessons are designed for educators to use with the Astro-Venture multimedia modules.

316

Theory and performance of plated thermocouples.  

NASA Technical Reports Server (NTRS)

A theory has been developed to describe the performance of thermocouples which have been formed by electroplating portions of one thermoelectric material with another. The electroplated leg of the thermocouple was modeled as a collection of infinitesimally small homogeneous thermocouples connected in series. Experiments were performed using several combinations of Constantan wire sizes and copper plating thicknesses. A transient method was used to develop the thermoelectric calibrations, and the theory was found to be in quite good agreement with the experiments. In addition, data gathered in a Soviet experiment were also found to be in close agreement with the theory.

Pesko, R. N.; Ash, R. L.; Cupschalk, S. G.; Germain, E. F.

1972-01-01

317

Design of Fracture Fixation Plate for Necessary and Sufficient Bone Stress Shielding  

NASA Astrophysics Data System (ADS)

The objective of treating the fractured bone is to achieve painless functioning of the bone and undisturbed healing at the fracture. Internal fixation by stiff bone-plate is one of the standard methods to achieve these objectives. Recently, there is considerable interest in the usage of compliant plates to enhance bone healing with reduced stress shielding. Herein, first an analytical solution is developed to determine screw forces in the bone-plate assembly that conforms the plate and the bone under bending load. Based on the analytical calculations, an optimal fixator plate selection criterion for necessary and sufficient stress shielding is proposed. Second, effectiveness of employing a non-homogeneous stiffness graded (SG) plate rather than a homogeneous stainless steel (SS) plate for stress shielding is investigated using a finite element method. It is found that stress shielding on bone by SG plate is less compared to SS plate.

Ramakrishna, Kotlanka; Sridhar, Idapalapati; Sivashanker, Sathiamoorthy; Khong, Kok Sun; Ghista, Dhanjoo N.

318

The magma ocean as an impediment to lunar plate tectonics  

NASA Technical Reports Server (NTRS)

The primary impediment to plate tectonics on the moon was probably the great thickness of its crust and particularly its high crust/lithosphere thickness ratio. This in turn can be attributed to the preponderance of low-density feldspar over all other Al-compatible phases in the lunar interior. During the magma ocean epoch, the moon's crust/lithosphere thickness ratio was at the maximum theoretical value, approximately 1, and it remained high for a long time afterwards. A few large regions of thin crust were produced by basin-scale cratering approximately contemporaneous with the demise of the magma ocean. However, these regions probably also tend to have uncommonly thin lithosphere, since they were directly heated and indirectly enriched in K, Th, and U by the same cratering process. Thus, plate tectonics on the moon in the form of systematic lithosphere subduction was impeded by the magma ocean.

Warren, Paul H.

1993-01-01

319

Nuclear reactor alignment plate configuration  

DOEpatents

An alignment plate that is attached to a core barrel of a pressurized water reactor and fits within slots within a top plate of a lower core shroud and upper core plate to maintain lateral alignment of the reactor internals. The alignment plate is connected to the core barrel through two vertically-spaced dowel pins that extend from the outside surface of the core barrel through a reinforcement pad and into corresponding holes in the alignment plate. Additionally, threaded fasteners are inserted around the perimeter of the reinforcement pad and into the alignment plate to further secure the alignment plate to the core barrel. A fillet weld also is deposited around the perimeter of the reinforcement pad. To accomodate thermal growth between the alignment plate and the core barrel, a gap is left above, below and at both sides of one of the dowel pins in the alignment plate holes through with the dowel pins pass.

Altman, David A; Forsyth, David R; Smith, Richard E; Singleton, Norman R

2014-01-28

320

Flat plate puncture test convergence study.  

SciTech Connect

The ASME Task Group on Computational Mechanics for Explicit Dynamics is investigating the types of finite element models needed to accurately solve various problems that occur frequently in cask design. One type of problem is the 1-meter impact onto a puncture spike. The work described in this paper considers this impact for a relatively thin-walled shell, represented as a flat plate. The effects of mesh refinement, friction coefficient, material models, and finite element code will be discussed. The actual punch, as defined in the transport regulations, is 15 cm in diameter with a corner radius of no more than 6 mm. The punch used in the initial part of this study has the same diameter, but has a corner radius of 25 mm. This more rounded punch was used to allow convergence of the solution with a coarser mesh. A future task will be to investigate the effect of having a punch with a smaller corner radius. The 25-cm thick type 304 stainless steel plate that represents the cask wall is 1 meter in diameter and has added mass on the edge to represent the remainder of the cask. The amount of added mass to use was calculated using Nelm's equation, an empirically derived relationship between weight, wall thickness, and ultimate strength that prevents punch through. The outer edge of the plate is restrained so that it can only move in the direction parallel to the axis of the punch. Results that are compared include the deflection at the edge of the plate, the deflection at the center of the plate, the plastic strains at radius r=50 cm and r=100 cm , and qualitatively, the distribution of plastic strains. The strains of interest are those on the surface of the plate, not the integration point strains. Because cask designers are using analyses of this type to determine if shell will puncture, a failure theory, including the effect of the tri-axial nature of the stress state, is also discussed. The results of this study will help to determine what constitutes an adequate finite element model for analyzing the puncture hypothetical accident.

Snow, Spencer (Idaho National Laboratories); Ammerman, Douglas James; Molitoris, David (Westinghouse); Tso, Chi-Fung (ARUP); Yaksh, Mike (NAC International)

2010-10-01

321

Aeroelastic Tailoring of a Plate Wing with Functionally Graded Materials  

NASA Technical Reports Server (NTRS)

This work explores the use of functionally graded materials for the aeroelastic tailoring of a metallic cantilevered plate-like wing. Pareto trade-off curves between dynamic stability (flutter) and static aeroelastic stresses are obtained for a variety of grading strategies. A key comparison is between the effectiveness of material grading, geometric grading (i.e., plate thickness variations), and using both simultaneously. The introduction of material grading does, in some cases, improve the aeroelastic performance. This improvement, and the physical mechanism upon which it is based, depends on numerous factors: the two sets of metallic material parameters used for grading, the sweep of the plate, the aspect ratio of the plate, and whether the material is graded continuously or discretely.

Dunning, Peter D.; Stanford, Bret K.; Kim, H. Alicia; Jutte, Christine V.

2014-01-01

322

Chromium plating pollution source reduction by plasma source ion implantation  

SciTech Connect

There is growing concern over the environmental toxicity and workers` health issues due to the chemical baths and rinse water used in the hard chromium plating process. In this regard the significant hardening response of chromium to nitrogen ion implantation can be environmentally beneficial from the standpoint of decreasing the thickness and the frequency of application of chromium plating. In this paper the results of a study of nitrogen ion implantation of chrome plated test flats using the non-line-of-sight Plasma Source Ion Implantation (PSII) process, are discussed. Surface characterization was performed using Scanning Electron Microscopy (SEM), Auger Electron Spectroscopy (AES), and Electron Spectroscopy for Chemical Analysis (ESCA). The surface properties were evaluated using a microhardness tester, a pin-on-disk wear tester, and a corrosion measurement system. Industrial field testing of nitrogen PSII treated chromium plated parts showed an improvement by a factor of two compared to the unimplanted case.

Chen, A.; Sridharan, K.; Dodd, R.A.; Conrad, J.R. [Univ. of Wisconsin, Madison, WI (United States); Qiu, X.; Hamdi, A.H.; Elmoursi, A.A.; Malaczynski, G.W. [General Motors Research Labs., Warren, MI (United States); Horne, W.G. [Empire Hard Chrome, Chicago, IL (United States)

1995-12-31

323

Stainless steel bipolar plates  

Microsoft Academic Search

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

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

2005-01-01

324

The Arctic plate boundary  

Microsoft Academic Search

Earthquakes provide information on the regional segmentation and seismotectonics of the poorly known boundary between the Eurasian and the North American plates from the Knipovich Ridge to the Laptev Sea continental margin. To this end, we have sorted earthquake epicenter locations and focal mechanism solutions from global and regional catalogs, assessed location errors and network detectabilities, and compiled a well-constrained

yvind Engen; Olav Eldholm; Hilmar Bungum

2003-01-01

325

Bipolar battery plate  

SciTech Connect

A method is described of forming a bipolar plate for a battery comprising the steps of: disposing metal pellets in each aperture of a perforated thermoplastic sheet to form an assembly; heating and pressing the assembly to seal the pellets into the apertures with first and second surfaces exposed in the opposite faces of the sheet.

Rowlette, J.J.

1987-04-21

326

INL HIP Plate Fabrication  

SciTech Connect

This document outlines the process used to bond monolithic fuel plates by Hot Isostatic Pressing (HIP). This method was developed at Idaho National Laboratory (INL) for the Reduced Enrichment for Research and Test Reactors (RERTR) program. These foils have been used in a number of irradiation experiments in support of the United States Global Threat Reduction Initiative (GTRI) program.

B. H. Park; C. R. Clark; J. F. Jue

2010-02-01

327

The Plate Tectonics Project  

Microsoft Academic Search

The Plate Tectonics Project is a multiday, inquiry-based unit that facilitates students as self-motivated learners. Reliable Web sites are offered to assist with lessons, and a summative rubric is used to facilitate the holistic nature of the project. After each topic (parts of the Earth, continental drift, etc.) is covered, the students will generate a portion of the summative assessment

Annamae J. Hein

2011-01-01

328

Earthquakes and Plates  

NSDL National Science Digital Library

The representation depicts global distribution of earthquakes. A world map shows the location of large earthquakes that occurred from 1975-1995. A slider at the bottom left of the map allows the user to change the map to reveal the location of major plates or to select both views layered on top of one another.

329

Plate Tectonics Quiz  

NSDL National Science Digital Library

This quiz for younger students asks them 10 questions about plate motions, rock types in continental and oceanic crust, crustal formation and mountain building, the supercontinent Pangea, and the theory of continental drift. A link to a page on continental drift provides information to answer the questions.

330

The Plate Tectonics Project  

ERIC Educational Resources Information Center

The Plate Tectonics Project is a multiday, inquiry-based unit that facilitates students as self-motivated learners. Reliable Web sites are offered to assist with lessons, and a summative rubric is used to facilitate the holistic nature of the project. After each topic (parts of the Earth, continental drift, etc.) is covered, the students will

Hein, Annamae J.

2011-01-01

331

Earth: Plates on the Move  

NSDL National Science Digital Library

In this activity, students explore how the movement of tectonic plates forms mountains, volcanoes, oceans, and earthquakes. It first describes the plates and the various types of interaction at plate boundaries. An interactive map of the world shows the relationship between plate boundaries and earthquakes, allowing the student to click on selected place to explore a volcano, mountain, hotspot or earthquake. They then zoom in the see how the plates are moving, play an animation about the plate interaction, and read a story about the event. In addition, a set of links lead to more detailed information.

332

Effects of transverse shearing flexibility on the postbuckling of plates loaded by inplane shear  

NASA Technical Reports Server (NTRS)

This paper presents buckling and postbuckling results for plates loaded by inplane shear. The buckling results have been plotted to show the effects of thickness on the stress coefficient for aluminum plates. Results are given for various length-to-width ratios. Postbuckling results for thin plates with transverse shearing flexibility are compared to results from classical theory. The problems considered are the postbuckling response of plates in shear made of aluminum and of a + or - 45 deg graphite-epoxy laminate. Thus the materials are isotropic and orthotropic, respectively. The plates are considered to be long with side edges simply supported, with various inplane edge conditions, and the plates are subject to a constant shearing displacement along the side edges. Characteristic curves presenting the average shear stress resultant as a function of the applied displacement are given. These curves indicate that change in inplane edge conditions influence plate postbuckling stiffness and that transverse shearing is important in some cases.

Stein, Manuel

1987-01-01

333

Panel flutter characteristics of sandwich plates with CNT reinforced facesheets using an accurate higher-order theory  

NASA Astrophysics Data System (ADS)

In this paper, the flutter characteristics of sandwich panels with carbon nanotube (CNT) reinforced face sheets are investigated using QUAD-8 shear flexible element developed based on higher-order structural theory. The formulation accounts for the realistic variation of the displacements through the thickness, the possible discontinuity in the slope at the interface, and the thickness stretch affecting the transverse deflection. The in-plane and rotary inertia terms are also included in the formulation. The first-order high Mach number approximation to linear potential flow theory is employed for evaluating the aerodynamic pressure. The solutions of the complex eigenvalue problem, developed based on Lagrange's equation of motion are obtained using the standard method for finding the eigenvalues. The accuracy of the present formulation is demonstrated considering the problems for which solutions are available. A detailed numerical study is carried out to bring out the efficacy of the higher-order model over the first-order theory and also to examine the influence of the volume fraction of the CNT, core-to-face sheet thickness, the plate thickness and the aspect ratio, damping and the temperature on the flutter boundaries and the associated vibration modes.

Sankar, A.; Natarajan, S.; Haboussi, M.; Ramajeyathilagam, K.; Ganapathi, M.

2014-10-01

334

Flexural Thickness Variations of the Maracaibo Block  

NASA Astrophysics Data System (ADS)

We estimated the lateral variations of the flexural thickness (Te) of the Maracaibo Block (MB) and its adjacent terranes using a 3D numerical approach. The calculation is based on solving the fourth-order partial differential equation that governs the bending of a thin plate fixed on its boundaries (zero displacement) and variable thickness (Te), using centered finite differences. The initial mechanical model accounts for: (1) four main loads: Mrida Andes (MA), Perij Range (PR), Santa Marta Mountains (SMM) and the Northern Colombian Andes (NCA) represented as a downs-sampled topographic grid (used as initial loads); (2) mechanical parameters extracted from previous research; (3) constant Te (25 km). Loads and Te were modified to fit the general basement configuration, and the residual topography to fit the down-sampled topography. The final result is a Te map that covers the MB and the surrounding sections of the South American Plate (SA). This map shows that the Te ranges from 30 km to 18 km, with a mean value of 23.57 km and a mode of 26 km. The orientation of the Te contours is roughly N45E, similar to the MA. The largest Te values are associated with the location of the SMM and with the deformed Guyana Shield to the southeast (Barinas Apure Basin), while the smallest ones to the MA-Maracaibo Basin flexural system. Te limit between SA and MB appears in the northern flank of the MA and the Bocon Fault, which is congruent with the gravimetric data of the area, where the Bouguer Anomaly low (that characterizes an locally compensated mountain ranged) is displaced to the north. The basement configuration within the Maracaibo Basin seems to be controlled by 2 important loads: (1) MA large load that generates the depocenter of the basin (at least 9 km); (2) PR and NCA limit the existence and outcrop of a large forebulge within the MB. Larger Te values in the north, particularly near SMM would explained why this mountain does not have sings of been isostatically compensated (as free air anomaly and Bouguer anomaly are positive). This could be related to the convergence of SA and the Caribbean Plate (CP) and the coupling related to this process. We conclude that the flexural history of the MB and the formation of the foreland basins were controlled by the lateral variations of the Te, originally generated by early crust thinning and graben formation, and by the unique distribution of loads. We also conclude that the isostatic state of the northern limit of the MB is related to large Te in SMM somehow associated to its geological and thermal history.

Arnaiz-Rodriguez, M. S.; Audemard, F. A.

2013-05-01

335

Highly conductive, multi-layer composite precursor composition to fuel cell flow field plate or bipolar plate  

DOEpatents

This invention provides a moldable, multiple-layer composite composition, which is a precursor to an electrically conductive composite flow field plate or bipolar plate. In one preferred embodiment, the composition comprises a plurality of conductive sheets and a plurality of mixture layers of a curable resin and conductive fillers, wherein (A) each conductive sheet is attached to at least one resin-filler mixture layer; (B) at least one of the conductive sheets comprises flexible graphite; and (C) at least one resin-filler mixture layer comprises a thermosetting resin and conductive fillers with the fillers being present in a sufficient quantity to render the resulting flow field plate or bipolar plate electrically conductive with a conductivity no less than 100 S/cm and thickness-direction areal conductivity no less than 200 S/cm.sup.2.

Jang, Bor Z. (Centerville, OH); Zhamu, Aruna (Centerville, OH); Guo, Jiusheng (Centerville, OH)

2011-02-15

336

Analytical modeling and vibration analysis of internally cracked rectangular plates  

NASA Astrophysics Data System (ADS)

This study proposes an analytical model for nonlinear vibrations in a cracked rectangular isotropic plate containing a single and two perpendicular internal cracks located at the center of the plate. The two cracks are in the form of continuous line with each parallel to one of the edges of the plate. The equation of motion for isotropic cracked plate, based on classical plate theory is modified to accommodate the effect of internal cracks using the Line Spring Model. Berger's formulation for in-plane forces makes the model nonlinear. Galerkin's method used with three different boundary conditions transforms the equation into time dependent modal functions. The natural frequencies of the cracked plate are calculated for various crack lengths in case of a single crack and for various crack length ratio for the two cracks. The effect of the location of the part through crack(s) along the thickness of the plate on natural frequencies is studied considering appropriate crack compliance coefficients. It is thus deduced that the natural frequencies are maximally affected when the crack(s) are internal crack(s) symmetric about the mid-plane of the plate and are minimally affected when the crack(s) are surface crack(s), for all the three boundary conditions considered. It is also shown that crack parallel to the longer side of the plate affect the vibration characteristics more as compared to crack parallel to the shorter side. Further the application of method of multiple scales gives the nonlinear amplitudes for different aspect ratios of the cracked plate. The analytical results obtained for surface crack(s) are also assessed with FEM results. The FEM formulation is carried out in ANSYS.

Joshi, P. V.; Jain, N. K.; Ramtekkar, G. D.

2014-10-01

337

HETEROTROPHIC PLATE COUNT (HPC) METHODOLOGY IN THE UNITED STATES  

EPA Science Inventory

ABSTRACT In the United States (U.S.), the history of bacterial plate counting 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 St...

338

Perforated plates for cryogenic regenerators and method of fabrication  

DOEpatents

Perforated plates (10) having very small holes (14) with a uniform diameter throughout the plate thickness are prepared by a "wire drawing" process in which a billet of sacrificial metal is disposed in an extrusion can of the plate metal, and the can is extruded and restacked repeatedly, converting the billet to a wire of the desired hole diameter. At final size, the rod is then sliced into wafers, and the wires are removed by selective etching. This process is useful for plate metals of interest for high performance regenerator applications, in particular, copper, niobium, molybdenum, erbium, and other rare earth metals. Er.sub.3 Ni, which has uniquely favorable thermophysical properties for such applications, may be incorporated in regions of the plates by providing extrusion cans (20) containing erbium and nickel metals in a stacked array (53) with extrusion cans of the plate metal, which may be copper. The array is heated to convert the erbium and nickel metals to Er.sub.3 Ni. Perforated plates having two sizes of perforations (38, 42), one of which is small enough for storage of helium, are also disclosed.

Hendricks, John B. (Huntsville, AL)

1994-01-01

339

Subduction of thick crust: the Alaska example (Invited)  

NASA Astrophysics Data System (ADS)

It is a paradigm of plate tectonics that oceanic lithosphere subducts readily, while lithosphere transporting much thicker continental crust does not. Analyses of plate buoyancy have included a variety of effects, such as eclogitization, crustal compositional stratification, and plate strength, but all lead to the conclusion that crust needs to be thinner than about 15-25 km in order to subduct. A test of this conclusion is underway in southern Alaska, where the Yakutat terrane is being driven by the Pacific plate into the Alaskan margin. Its crust is 15-30 km thick, varying along strike, with a seismic velocity structure resembling an oceanic plateau; thus it spans the predicted limit in thickness of subductable crust. In the eastern thicker part, the terrane appears to be colliding and driving orogenesis in the St. Elias-Chugach ranges, although voluminous volcanism of the Wrangell Volcanic Field may be a consequence of some crust subducting. Farther west, the Yakutat terrane is 15-20 km thick and clearly subducting beneath the Prince William Sound and Kenai Peninsula. It forms the slab subducting beneath the central Alaska Range 400 km inland. The thick crust has been imaged at all depths less than 130 km, through receiver functions, travel-time tomography, and offshore by active-source imaging, with similar structure in most images. Greater than 130 km depth the imaged crust vanishes in seismic images, consistent with predicted depths of eclogitization of weakly hydrated metagabbroic crust, and the lack of a velocity contrast between eclogite and peridotite. Lithosphere including the thick Yakutat crust gives a net buoyancy close to neutral, so its subduction will depend on other factors. The high buoyancy may be responsible for the remarkably shallow dip of the plate at depths less than 50 km, producing one of the widest seismogenic thrust zones on the planet, allowing it to host the great (Mw 9.3) 1964 Gulf of Alaska earthquake. The shallow dip may also aid in driving deformation in the Alaska Range, several hundred km inland. Analogous mountain-building may occur at other sites where oceanic plateaus or rises subduct, for example in southeast Costa Rica, or where leading edges of continents subduct, such as Timor or northern New Guinea.

Abers, G. A.; Kim, Y.; Christensen, D. H.

2013-12-01

340

The Influence of Pre-existing Deformation on GMA Welding Distortion in Thin Steel Plates  

NASA Astrophysics Data System (ADS)

Weld distortion is particularly problematic for large thin structures that are used in the assembly of ships. The drive toward lighter ships and thinner plate is restricted by the significant increase in distortion as the plate thickness decreases. The influence of pre-existing deformation in the plates to be joined on the resultant distortion in gas metal arc welded structure has been studied. DH-36 steel plate surface profiles were measured before and after the butt welding of two plates 1000 500 4 mm in size. Three dimensional finite element models that incorporate the initial plate profile have been created to simulate the welding process and to examine the relationship between the final welded plate profiles and the initial deformation present in the plates. Both symmetric and asymmetric models were considered. A significant variation in the unwelded base plates' initial distortion was observed. Generally, it has been found that if an out-of-plane deformation exists in a plate prior to welding, the level of distortion further increases in the same direction following welding. The final distortions are strongly related to the initial plate profiles. The residual stress distributions in the plates are also to some extent affected by the level of distortion initially present.

Davies, C. M.; Ahn, J.; Tsunori, M.; Dye, D.; Nikbin, K. M.

2015-01-01

341

The Influence of Pre-existing Deformation on GMA Welding Distortion in Thin Steel Plates  

NASA Astrophysics Data System (ADS)

Weld distortion is particularly problematic for large thin structures that are used in the assembly of ships. The drive toward lighter ships and thinner plate is restricted by the significant increase in distortion as the plate thickness decreases. The influence of pre-existing deformation in the plates to be joined on the resultant distortion in gas metal arc welded structure has been studied. DH-36 steel plate surface profiles were measured before and after the butt welding of two plates 1000 500 4 mm in size. Three dimensional finite element models that incorporate the initial plate profile have been created to simulate the welding process and to examine the relationship between the final welded plate profiles and the initial deformation present in the plates. Both symmetric and asymmetric models were considered. A significant variation in the unwelded base plates' initial distortion was observed. Generally, it has been found that if an out-of-plane deformation exists in a plate prior to welding, the level of distortion further increases in the same direction following welding. The final distortions are strongly related to the initial plate profiles. The residual stress distributions in the plates are also to some extent affected by the level of distortion initially present.

Davies, C. M.; Ahn, J.; Tsunori, M.; Dye, D.; Nikbin, K. M.

2014-11-01

342

Tectonic Plates, Earthquakes, and Volcanoes  

NSDL National Science Digital Library

The representation shows earthquake and volcanic activity corresponds to plate boundaries. This interactive topographical map with the ocean water removed shows the boundaries of major plates and the locations of major volcanic eruptions and earthquakes worldwide.

343

EGDT-1040 AutoCAD - Drawing Standards  

NSDL National Science Digital Library

Lines Letters Location - Many Items Contribute To Drawing Standards Core Standards: The following standard from the Technical Design 1 standards will be promoted on this page. Standard 2 Students will be able to understand and demonstrate the use of the alphabet of Lines. Objective 1 Understand and demonstrate the recommended thickness of lines.

Jonathan Allred

2012-09-05

344

New Eddy Current Probe for Thickness Gauging of Conductive Materials  

NASA Technical Reports Server (NTRS)

The accurate measure of material thickness is important for many non-destructive evaluation applications. Factors such as corrosion damage can jeopardize structural integrity through material thinning and process control considerations often mandate strict limits on material dimensions. Access to the material under test can be limited to a single side and large areas may need to be examined in a small time period. In an effort to enhance the effectiveness of material thickness measurements a flux focusing eddy current probe has been developed at NASA Langley Research Center. The probe provides an accurate measure of the thickness of conducting materials from a single sided measurement. It is straight forward to use and can be easily automated for production line testing. The probe also requires only minimal instrumentation and power so that extremely portable units can be manufactured at a low cost. This new eddy current probe has been used to accurately measure the thickness of aluminum alloy plates with a resolution of greater than 0.001 in. (25 microns). Simulated corrosion damage has also been detected on both single layer and multi-layer samples. The present work will explain the output voltage dependence of the device as a function of material thickness and present experimental results for thickness gauging and corrosion detection.

Wincheski, Buzz; Fulton, Jim; Nath, Shridhar; Namkung, Min

1993-01-01

345

International Thermonuclear Experimental Reactor (ITER) divertor plate performance and lifetime considerations  

SciTech Connect

The ITER divertor plate performance during the technology phase of operation has been analyzed. High-Z materials, such as tungsten and tantalum, have been considered as plasma side materials, and refractory metal alloys, Ta-10W, TZM, Nb-1Zr, and V-15Cr-5Ti, plus copper alloys have been considered as the structural materials. The fatigue lifetime have been predicted for structural plates and for duplex plates with the plasma side material bonded to the structure. The results indicate that refractory alloys have a comparable or improved performance to copper alloys. Peak allowable heat fluxes for these analyses are in the range of 15--20 MW/m{sup 2} for 2 mm thick structural plates and 7--11 MW/m{sup 2} for 4 mm thick duplex plates. 4 refs., 55 figs., 6 tabs.

Mattas, R.F.

1990-03-01

346

Three-dimensional stress constraint in an elastic plate with a notch  

Microsoft Academic Search

This paper presents analytical solutions for the three-dimensional stress distribution around typical stress concentrators in an isotropic plate of arbitrary thickness. Based on the assumption of a generalised plane-strain theory, which assumes that the through-the-thickness extensional strain is uniform in the thickness direction, an exact three-dimensional solution has been obtained for an annulus subjected to arbitrary loading along its edges.

A. Kotousov; C. H. Wang

2002-01-01

347

Glacial isostasy and plate motion  

Microsoft Academic Search

The influence of glacial-isostatic adjustment (GIA) on the motion of tectonic plates is usually neglected. Employing a recently developed numerical approach, we examine the effect of glacial loading on the motion of the Earths tectonic plates where we consider an elastic lithosphere of laterally variable strength and the plates losely connected by low viscous zones. The aim of this paper

Volker Klemann; Zdenek Martinec; Erik R. Ivins

2008-01-01

348

Gauge Measures Thicknesses Of Blankets  

NASA Technical Reports Server (NTRS)

Tool makes highly repeatable measurements of thickness of penetrable blanket insulation. Includes commercial holder for replaceable knife blades, which holds needle instead of knife. Needle penetrates blanket to establish reference plane. Ballasted slider applies fixed preload to blanket. Technician reads thickness value on scale.

Hagen, George R.; Yoshino, Stanley Y.

1991-01-01

349

Regional geotherms and lithospheric thickness  

Microsoft Academic Search

Continental and oceanic geotherm families parametric in surface heat flow intersect the mantle solidus at a depth coincident with the top of the seismic low-velocity zone, thus allowing surface heat-flow variations to be used to map the thickness of the lithosphere on a global scale. Thermal models were developed that predict a lithospheric thickness of a few tens of kilometers

David S. Chapman; Henry N. Pollack

1977-01-01

350

Residual stress measurements in a thick, dissimilar aluminum alloy friction stir weld  

Microsoft Academic Search

Plates (25.4mm thick) of aluminum alloys 7050-T7451 and 2024-T351 were joined in a butt joint by friction stir welding (FSW). A 54mm long test specimen was removed from the parent plate, and cross-sectional maps of residual stresses were measured using neutron diffraction and the contour method. The stresses in the test specimen peaked at only about 32MPa and had the

Michael B. Prime; Thomas Gnupel-Herold; John A. Baumann; Richard J. Lederich; David M. Bowden; Robert J. Sebring

2006-01-01

351

Microchannel plate streak camera  

DOEpatents

An improved streak camera in which a microchannel plate electron multiplier is used in place of or in combination with the photocathode used in prior streak cameras. The improved streak camera is far more sensitive to photons (uv to gamma-rays) than the conventional x-ray streak camera which uses a photocathode. The improved streak camera offers gamma-ray detection with high temporal resolution. It also offers low-energy x-ray detection without attenuation inside the cathode. Using the microchannel plate in the improved camera has resulted in a time resolution of about 150 ps, and has provided a sensitivity sufficient for 1000 keV x-rays.

Wang, C.L.

1984-09-28

352

Microchannel plate streak camera  

DOEpatents

An improved streak camera in which a microchannel plate electron multiplier is used in place of or in combination with the photocathode used in prior streak cameras. The improved streak camera is far more sensitive to photons (UV to gamma-rays) than the conventional x-ray streak camera which uses a photocathode. The improved streak camera offers gamma-ray detection with high temporal resolution. It also offers low-energy x-ray detection without attenuation inside the cathode. Using the microchannel plate in the improved camera has resulted in a time resolution of about 150 ps, and has provided a sensitivity sufficient for 1000 KeV x-rays.

Wang, Ching L. (Livermore, CA)

1989-01-01

353

Microchannel plate streak camera  

DOEpatents

An improved streak camera in which a microchannel plate electron multiplier is used in place of or in combination with the photocathode used in prior streak cameras is disclosed. The improved streak camera is far more sensitive to photons (UV to gamma-rays) than the conventional x-ray streak camera which uses a photocathode. The improved streak camera offers gamma-ray detection with high temporal resolution. It also offers low-energy x-ray detection without attenuation inside the cathode. Using the microchannel plate in the improved camera has resulted in a time resolution of about 150 ps, and has provided a sensitivity sufficient for 1,000 KeV x-rays. 3 figs.

Wang, C.L.

1989-03-21

354

North American plate dynamics  

NASA Technical Reports Server (NTRS)

Deformation within the North American plate in response to various tectonic processes is modeled using an elastic finite element analysis. The tectonic processes considered in the modeling include ridge forces associated with the normal thermal evolution of oceanic lithosphere, shear and normal stresses transmitted across transforms, normal stresses transmitted across convergent boundaries, stresses due to horizontal density contrasts within the continent, and shear tractions applied along the base of the plate. Model stresses are calculated with respect to a lithostatic reference stress state. Shear stresses transmitted across transform boundaries along the San Andreas and Caribbean are small, of the order of 5-10 MPa. Also, compressive stresses of the order of 5-10 MPa transmitted across the major transforms improve the fit to the data. Compressive stresses across convergent margins along the Aleutians and the Middle America trench are important.

Richardson, Randall M.; Reding, Lynn M.

1991-01-01

355

New heat transfer and friction factor design data for perforated plate heat exchangers  

NASA Astrophysics Data System (ADS)

Perforated plate heat exchangers have been found to have inherently low axial conduction and are therefore excellent candidates for cryogenic applications where an all-metal design is required. A total of three plate cores were tested; two were chemically etched and the other mechanically punched. Hole size, percent open area and plate thickness parameters were varied among the plates. Experimental results were compared to analytical projections and found to differ significantly. The single-blow, transient test technique was used to determine the heat transfer coefficients and the isothermal pressure drop test was used to determine friction factors, as a function of Reynolds number.

Hubbell, Richard H.; Cain, Christina L.

356

Ultrasonic testing of plates containing edge cracks  

NASA Technical Reports Server (NTRS)

The stress wave factor (SWF) signal is utilized for the nondestructive evaluation of plates containing perpendicular edge cracks. The effects of the existence lateral location and depth of the crack on the magnitude spectra of individual reflections in the SWF signal are studied. If the reflections in the SWF signal are not overlapped the short time Fourier analysis is applied. If the reflections are overlapped the short time homomorphic analysis (cepstrum analysis) is applied. Several reflections which have average resonant frequencies approximately at 0.9, 1.3, and 1.7 MHz are analyzed. It is observed that the magnitude ratios evaluated at average resonant frequencies decrease more with increasing d/h if the crack is located between the transducers, where h is plate thickness and d is crack depth. Moreover, for the plates, crack geometries, reflections, and frequencies considered, the average decibel drop depends mainly on the dimensionless parameter d/h and it is approximately -1 dB per 0.07 d/h. Changes in the average resonant frequencies of the magnitude spectra are also observed due to changes in the location of the crack.

Williams, J. H., Jr.; Karagulle, H.; Lee, S. S.

1985-01-01

357

Plated wire memory subsystem  

NASA Technical Reports Server (NTRS)

The work performed entailed the design, development, construction and testing of a 4000 word by 18 bit random access, NDRO plated wire memory for use in conjunction with a spacecraft imput/output unit and central processing unit. The primary design parameters, in order of importance, were high reliability, low power, volume and weight. A single memory unit, referred to as a qualification model, was delivered.

Reynolds, L.; Tweed, H.

1972-01-01

358

Plate Tectonics: The Mechanism  

NSDL National Science Digital Library

This text explains how detailed mapping of the ocean floor led scientists like Howard Hess and R. Deitz to revive the Holmes convection theory. Hess and Deitz modified the theory considerably and called their new theory Sea-floor Spreading. Among the seafloor features that supported the sea-floor spreading hypothesis were: mid-oceanic ridges, deep sea trenches, island arcs, geomagnetic patterns, and fault patterns. These features are treated in detail and related to the current Theory of Plate Tectonics.

359

Plate motion and deformation  

SciTech Connect

Our goal is to understand the motions of the plates, the deformation along their boundaries and within their interiors, and the processes that control these tectonic phenomena. In the broadest terms, we must strive to understand the relationships of regional and local deformation to flow in the upper mantle and the rheological, thermal and density structure of the lithosphere. The essential data sets which we require to reach our goal consist of maps of current strain rates at the earth's surface and the distribution of integrated deformation through time as recorded in the geologic record. Our success will depend on the effective synthesis of crustal kinematics with a variety of other geological and geophysical data, within a quantitative theoretical framework describing processes in the earth's interior. Only in this way can we relate the snapshot of current motions and earth structure provided by geodetic and geophysical data with long-term processes operating on the time scales relevant to most geological processes. The wide-spread use of space-based techniques, coupled with traditional geological and geophysical data, promises a revolution in our understanding of the kinematics and dynamics of plate motions over a broad range of spatial and temporal scales and in a variety of geologic settings. The space-based techniques that best address problems in plate motion and deformation are precise space-geodetic positioning -- on land and on the seafloor -- and satellite acquisition of detailed altimetric and remote sensing data in oceanic and continental areas. The overall science objectives for the NASA Solid Earth Science plan for the 1990's, are to Understand the motion and deformation of the lithosphere within and across plate boundaries'', and to understand the dynamics of the mantle, the structure and evolution of the lithosphere, and the landforms that result from local and regional deformation. 57 refs., 7 figs., 2 tabs.

Minster, B.; Prescott, W.; Royden, L.

1991-02-01

360

Friction Stir Welding of Curved Plates  

NASA Technical Reports Server (NTRS)

Friction stir welding (FSW) is a remarkable technology for making butt and lap joints in aluminum alloys. The process operates by passing a rotating tool between two closely butted plates. This process generates heat and the heated material is stirred from both sides of the plates to generate a high quality weld. Application of this technique has a very broad field for NASA. In particular, NASA is interested in using this welding process to manufacture tanks and curved elements. Therefore, this research has been oriented to the study the FSW of curved plates. The study has covered a number of topics that are important in the model development and to uncover the physical process involve in the welding itself. The materials used for the experimental welds were as close to each other as we could possibly find, aluminum 5454-0 and 5456-0 with properties listed at http://matweb.com. The application of FSW to curved plates needs to consider the behavior that we observed in this study. There is going to be larger force in the normal direction (Fz) as the curvature of the plate increases. A particular model needs to be derived for each material and thickness. A more complete study should also include parameters such as spin rate, tool velocity, and power used. The force in the direction of motion (Fx) needs to be reconsidered to make sure of its variability with respect to other parameters such as velocity, thickness, etc. It seems like the curvature does not play a role in this case. Variations in temperature were found with respect to the curvature. However, these changes seem to be smaller than the effect on Fz. The temperatures were all below the melting point. We understand now that the process of FSW produces a three dimensional flow of material that takes place during the weld. This flow needs to be study in a more detailed way to see in which directions the flow of material is stronger. It could be possible to model the flow using a 2-dimensional model in the particular directions where the flow moves faster. More experimental information is required to enrich the knowledge about FSW, and from this point, derive useful mathematical formulas to optimize the process and the design of the machines that will perform it. More experiments and experimental equipment are required to uncover the mathematics of the process.

Sanchez, Nestor

1999-01-01

361

Injection moulded low cost bipolar plates for PEM fuel cells  

Microsoft Academic Search

The development of bipolar plates that can be produced by standard mass production techniques is a main issue for the commercialization of PEM fuel cells, as bipolar plates contribute significantly to the cost structure of PEM stacks. In recent years, the University of Duisburg-Essen together with the Zentrum fr BrennstoffzellenTechnik GmbH (ZBT) has identified a number of carbonpolymer composites with

A. Heinzel; F. Mahlendorf; O. Niemzig; C. Kreuz

2004-01-01

362

Swelling Properties of Thin-Plate Hydrogels under Mechanical Constraint  

NASA Astrophysics Data System (ADS)

The static swelling ratio of thin-plate poly(N-isopropylacylamide) (NIPA) gel was studied under mechanical constraint; one surface is mechanically and chemically clamped on a glass plate, therefore the gel can swell and shrink only along a one-dimensional thickness-direction. The equilibrium thickness was measured as functions of temperature including the volume phase transition point. Compared with the free NIPA gel without mechanical constraint, the transition temperature slightly increased, and the total volume decreased (or increased) below (or above) 30C. The swelling ratio in the swollen state was found to depend on the thickness at gelation. The results were compared with the equation of states of gels on the basis of the Flory-type theory. In addition, the swelling and shrinking kinetics between two different swollen states were studied by measuring the temporal evolution of the thickness in response to the abrupt temperature change. The power of the kinetics was compared with that of the free NIPA gels as well as that of the thin-plate NIPA gels with two opposing surfaces clamped.

Suzuki, Atsushi; Wu, Xi Rong; Kuroda, Makoto; Ishiyama, Eiichi; Kanama, Daisuke

2003-02-01

363

Discovering Plate Boundaries  

NSDL National Science Digital Library

Discovering Plate Boundaries is based on 5 world maps containing earthquake, volcano, topography, satellite gravity, and seafloor age data. The novel aspect of the exercise is the "jigsaw" manner in which student groups access the maps and use them to discover, classify, and describe plate boundary types. The exercise is based only on observation and description, which makes it useful at a wide variety of levels; it has been used successfully in 5th grade classes, as well as in non-major earth science classes. The exercise is based on a set of wall maps that are not consumed during the exercise. Other inexpensive materials required include two 11x17 black and white copies per student and colored pencils. Because the exercise is not based on student access to the web, it is not dependent on classroom technology equipment. The exercise takes three 50-minute class periods to complete, and involves the students in making presentations to one another in small groups as well as to the whole class. The students come away from the exercise with knowledge of the key features of each type of plate boundary and a sense of why each looks and acts the way it does.

Dale Sawyer

1997-09-15

364

Effective radiation attenuation calibration for breast density: compression thickness influences and correction  

Microsoft Academic Search

BACKGROUND: Calibrating mammograms to produce a standardized breast density measurement for breast cancer risk analysis requires an accurate spatial measure of the compressed breast thickness. Thickness inaccuracies due to the nominal system readout value and compression paddle orientation induce unacceptable errors in the calibration. METHOD: A thickness correction was developed and evaluated using a fully specified two-component surrogate breast model.

John J Heine; Ke Cao; Jerry A Thomas

2010-01-01

365

Three-dimensional structure of the shell plate assembly of the chiton Tonicella marmorea and its biomechanical consequences.  

PubMed

This study investigates the three-dimensional structure of the eight plate exoskeletal (shell) assembly of the chiton Tonicella marmorea. X-ray micro-computed tomography and 3D printing elucidate the mechanism of conformational change from a passive (slightly curved, attached to surface) to a defensive (rolled, detached from surface) state of the plate assembly. The passive and defensive conformations exhibited differences in longitudinal curvature index (0.43 vs. 0.70), average plate-to-plate overlap (?62% vs. ?48%), cross-sectional overlap heterogeneity (60-82.5% vs. 0-90%, fourth plate), and plate-to-plate separation distance (100% increase in normalized separation distance between plates 4 and 5), respectively. The plate-to-plate interconnections consist of two rigid plates joined by a compliant, actuating muscle, analogous to a geometrically structured shear lap joint. This work provides an understanding of how T. marmorea achieves the balance between mobility and protection. In the passive state, the morphometry of the plates and plate-to-plate interconnections results in an approximately continuous curvature and constant armor thickness, resulting in limited mobility but maximum protection. In the defensive state, the underlying soft tissues gain protection and the chiton gains mobility through tidal flow, but regions of vulnerability open dorsally, due to the increase in plate-to-plate separation and decrease in plate-to-plate overlap. Lastly, experiments using optical and scanning electron microscopy, mercury porosimetry, and Fourier-transform infrared spectroscopy explore the microstructure and spatial distribution of the six layers within the intermediate plates, the role of multilayering in resisting predatory attacks, and the detection of chitin as a major component of the intra-plate organic matrix and girdle. PMID:22248452

Connors, Matthew J; Ehrlich, Hermann; Hog, Martin; Godeffroy, Clemence; Araya, Sergio; Kallai, Ilan; Gazit, Dan; Boyce, Mary; Ortiz, Christine

2012-02-01

366

Advances in sputtered and ion plated solid film lubrication  

NASA Technical Reports Server (NTRS)

The glow discharge or ion assisted vacuum deposition techniques, primarily sputtering and ion plating, have rapidly emerged and offer great potential to deposit solid lubricants. The increased energizing of these deposition processes lead to improved adherence and coherence, favorable morphological growth, higher density, and reduced residual stresses in the film. These techniques are of invaluable importance where high precision machines tribo-components require very thin, uniform lubricating films (0.2 m), which do not interface with component tolerances. The performance of sputtered MoS2 films and ion plated Au and Pb films are described in terms of film thickness, coefficient of friction, and wear lives.

Spalvins, T.

1985-01-01

367

On the breakup of tectonic plates by polar wandering  

NASA Technical Reports Server (NTRS)

The equations for the stresses in a homogeneous shell of uniform thickness caused by a shift of the axis of rotation are derived. The magnitude of these stresses reaches a maximum value of the order of 10 to the 9th power dyn/sq cm, which is sufficient for explaining a tectonic breakup. In order to deduce the fracture pattern according to which the breakup of tectonic plates can be expected the theory of plastic deformation of shells is applied. The analysis of this pattern gives an explanation of the existing boundary systems of the major tectonic plates as described by Morgan (1968), LePichon (1968) and Isacks et al. (1968).

Liu, H.-S.

1974-01-01

368

Welded tie plate feasibility study for ITER central solenoid structure  

NASA Astrophysics Data System (ADS)

The result of a Nitronic 50 (N50) weld-screening program conducted in support of CS-Tie Plate Structure Design and Development is reported here. The goal of this program is to evaluate four different weld practices and to select the best weld practice for thick section welding of the N50 tie plate structure. The structure design specifies both the weld and base metals have the same minimum mechanical properties requirements. The criteria for selecting the best weld practice are based on the combination of the 295 K tensile properties and the 4 K-tensile, fatigue, and fracture-toughness properties.

Walsh, R.; McRae, D.; Dalder, E.; Litherland, S.; Goddard, R.; Han, K.; Trosen, M.; Kuhlmann, D. D.

2014-01-01

369

Abstract--In electrically substituted radiometers, the ultra low noise control of the temperature is required. In this framework, we present results dedicated to the temperature regulation of copper plates, 3 cm diameter and 1 mm thick, using YBa2Cu3O7-d  

E-print Network

. A low noise operation at this level means that standard low noise analog IC circuits and components must conductance Gt is deduced as their ratio. After these first parameters are fixed, the thermal capacitance Ct holder is designed for an operating temperature above the liquid nitrogen temperature (77 K

Paris-Sud XI, Université de

370

Symmetries in laminated composite plates  

NASA Technical Reports Server (NTRS)

The different types of symmetry exhibited by laminated anisotropic fibrous composite plates are identified and contrasted with the symmetries of isotropic and homogeneous orthotropic plates. The effects of variations in the fiber orientation and the stacking sequence of the layers on the symmetries exhibited by composite plates are discussed. Both the linear and geometrically nonlinear responses of the plates are considered. A simple procedure is presented for exploiting the symmetries in the finite element analysis. Examples are given of square, skew and polygonal plates where use of symmetry concepts can significantly reduce the scope and cost of analysis.

Noor, A. K.

1976-01-01

371

Simultaneous measurement of refractive index and thickness with a convergent beam  

NASA Astrophysics Data System (ADS)

A new approach to the simultaneous measurement of refractive index and thickness based on the focus shifts of a convergent beam intercepted by a test plate is proposed. By using ray optics, a defined focus shift can be derived as a function of the refractive index and thickness as well as the angular position of the test plate with respect to the optical axis. From a pair of focus shifts obtained at two different angular positions, it is shown that the desired measurands can be simultaneously determined without prior knowledge of either parameter. A simulation result for the proposed concept based on graphically solving the equations of their respective focus shifts is presented.

Hii, King Ung; Kwek, Kuan Hiang

2014-09-01

372

Alumina plate containing photosystem I reaction center complex oriented inside plate-penetrating silica nanopores.  

PubMed

The photosynthetic photosystem I reaction center complex (PSI-RC), which has a molecular diameter of 21 nm with 100 pigments, was incorporated into silica nanopores with a 100-nm diameter that penetrates an alumina plate of 60-?m thickness to make up an inorganic-biological hybrid photocell. PSI-RCs, purified from a thermophilic cyanobacterium, were stable inside the nanopores and rapidly photoreduced a mediator dye methyl viologen. The reduced dye was more stable inside nanopores suggesting the decrease of dissolved oxygen. The analysis by a cryogenic electron spin paramagnetic resonance indicated the oriented arrangement of RCs inside the 100-nm nanopores, with their surface parallel to the silica wall and perpendicular to the plane of the alumina plate. PSI RC complex in the semicrystalline orientation inside silica nanopores can be a new type of light energy conversion unit to supply strong reducing power selectively to other molecules inside or outside nanopores. PMID:23888886

Kamidaki, Chihiro; Kondo, Toru; Noji, Tomoyasu; Itoh, Tetsuji; Yamaguchi, Akira; Itoh, Shigeru

2013-08-22

373

Conducted noise suppression effect up to 3 GHz by NiZn ferrite film plated at 90?C directly onto printed circuit board  

NASA Astrophysics Data System (ADS)

A NiZn ferrite film (3 ?m thick) was deposited at 90 C by the spin-spray ferrite plating from an aqueous solution onto a 50 ? microstrip line formed on an epoxy printed circuit board (PCB). A strong magnetic loss was caused by the ferrite film in a GHz range, ?Ploss reaching 67% attenuation at 3 GHz, the upper limit of our measurement. Furthermore, the reflection loss was very weak, S11 being smaller than 7%. Thus plated NiZn ferrite films hold strong promise to be actually applied to a type of thin film electromagnetic noise suppressors; the films can be directly deposited onto noise sources (semiconductor elements or electronic circuits) to attenuate conducted-electromagnetic noises in the GHz range. Because the plated NiZn ferrite film was magnetically isotropic in film plane, the noise suppressors will be isotropic, attenuating noise electromagnetic waves radiated from any directions. The NiZn ferrite film was also plated on a flat glass substrate as a standard, which exhibited natural resonance frequency of fr=500 MHz and initial real permeability of ?'=50. Compared to these values, the film on the PCB had higher fr of 850 MHz, though reduced in ?' to 40. But the spectrum of the imaginary permeability ?? shifted to a higher frequency range. This facilitated the strong magnetic loss at the high frequencies. The higher fr for the film on the PCB may be attributed to the undulated columnar structure of the film which was observed by scanning electron microscopy.

Kondo, K.; Chiba, T.; Ono, H.; Yoshida, S.; Shimada, Y.; Matsushita, N.; Abe, M.

2003-05-01

374

High Frequency Ultrasound for Evaluation of Intimal Thickness  

PubMed Central

Background: The measurement of carotid intima-medial thickness is a well validated measure of cardiovascular risk. Although atherosclerosis occurs in the intima, this arterial layer is not measured alone due to limitation in ultrasound resolution with standard frequency probes. Methods: We evaluated the feasibility of using a 55-MHz ultrasound system with high resolution to measure intima thickness in several vascular territories compared to a standard frequency probe. Results: The intima and medial thickness was measured in the brachial, radial and tibial arteries in 10 healthy subjects and 5 subjects with peripheral arterial disease. The high frequency ultrasound probe showed superior resolution compared to the standard frequency probe allowing for measurement of intima separately from media. Conclusions: The intima can be measured independently of media with a high degree of reproducibility using a high frequency probe. This technology may allow for early detection of cardiovascular risk and extend knowledge about the physiological changes in the early atherosclerotic development. PMID:19647399

Mohler, Emile R.; Sibley, Alexandra A.; Schultz, Susan M.; Zhang, Lifeng; Sehgal, Chandra M.

2009-01-01

375

Shape from equal thickness contours  

SciTech Connect

A unique imaging modality based on Equal Thickness Contours (ETC) has introduced a new opportunity for 3D shape reconstruction from multiple views. We present a computational framework for representing each view of an object in terms of its object thickness, and then integrating these representations into a 3D surface by algebraic reconstruction. The object thickness is inferred by grouping curve segments that correspond to points of second derivative maxima. At each step of the process, we use some form of regularization to ensure closeness to the original features, as well as neighborhood continuity. We apply our approach to images of a sub-micron crystal structure obtained through a holographic process.

Cong, G.; Parvin, B.

1998-05-10

376

Comparison of resorbable plates and titanium plates for fixation stability of combined mandibular symphysis and angle fractures  

PubMed Central

Objectives We compared resorbable plates with titanium plates for treatment of combined mandibular angle and symphyseal fractures. Materials and Methods Patients with mandibular angle and symphysis fractures were divided into two groups. The control (T) group received titanium plates while the experimental (R) group received resorbable plates. All procedures were carried out under general anesthesia using standard surgical techniques. We compared the frequency of wound dehiscence, development of infection, malocclusion, malunion, screw breakage, and any other technical difficulties between the two groups. Results Thirteen patients were included in the R group, where 39 resorbable plates were applied. The T group consisted of 16 patients who received 48 titanium plates. The mean age in the R and T groups was 28.29 and 24.23 years, respectively. Primary healing of the fractured mandible was obtained in all patients in both groups. Postoperative complications were minor and transient. Moreover, there were no significant differences in the rates of various complications between the two groups. Breakage of 3 screws during the perioperative period was seen in the R group, while no screws or plates were broken in the T group. Conclusion Resorbable plates can be used to stabilize combined mandibular angle and symphysis fractures. PMID:25551093

Lim, Ho-Yong; Jung, Chang-Hwa; Kim, Seong-Yong; Cho, Jin-Yong; Ryu, Jae-Young

2014-01-01

377

Constraining the Mean Crustal Thickness on Mercury  

NASA Technical Reports Server (NTRS)

The topography of Mercury is poorly known, with only limited radar and stereo coverage available. However, radar profiles reveal topographic contrasts of several kilometers over wavelengths of approximately 1000 km. The bulk of Mercury's geologic activity took place within the first 1 Ga of the planet's history), and it is therefore likely that these topographic features derive from this period. On Earth, long wavelength topographic features are supported either convectively, or through some combination of isostasy and flexure. Photographic images show no evidence for plume-like features, nor for plate tectonics; I therefore assume that neither convective support nor Pratt isostasy are operating. The composition and structure of the crust of Mercury are almost unknown. The reflectance spectrum of the surface of Mercury is similar to that of the lunar highlands, which are predominantly plagioclase. Anderson et al. used the observed center-of-mass center-of-figure offset together with an assumption of Airy isostasy to infer a crustal thickness of 100-300 km. Based on tidal despinning arguments, the early elastic thickness (T(sub e)) of the (unfractured) lithosphere was approximately equal to or less than 100 km. Thrust faults with lengths of up to 500 km and ages of about 4 Ga B.P. are known to exist on Mercury. Assuming a semicircular slip distribution and a typical thrust fault angle of 10 degrees, the likely vertical depth to the base of these faults is about 45 km. More sophisticated modelling gives similar or slightly smaller answers. The depth to the base of faulting and the elastic layer are usually similar on Earth, and both are thought to be thermally controlled. Assuming that the characteristic temperature is about 750 K, the observed fault depth implies that the heat flux at 4 Ga B.P. is unlikely to be less than 20 mW m(exp -2) for a linear temperature gradient. For an elastic thickness of 45 km, topography at 1000 km wavelength is likely to be about 60% compensated. There are thus likely to be considerable lateral variations in crustal thickness. Additional information is contained in the original extended abstract.

Nimmo, F.

2001-01-01

378

Focusing and waveguiding of Lamb waves in micro-fabricated piezoelectric phononic plates.  

PubMed

This paper presents results on the numerical and experimental studies of focusing and waveguiding of the lowest anti-symmetric Lamb wave in micro-fabricated piezoelectric phononic plates. The phononic structure was based on an AT-cut quartz plate and consisted of a gradient-index phononic crystal (GRIN PC) lens and a linear phononic plate waveguide. The band structures of the square-latticed AT-cut quartz phononic crystal plates with different filling ratios were analyzed using the finite element method. The design of a GRIN PC plate lens which is attached with a linear phononic plate waveguide is proposed. In designing the waveguide, propagation modes in square-latticed PC plates with different waveguide widths were studied and the results were served for the experimental design. In the micro-fabrication, deep reactive ion etching (Deep-RIE) process with a laboratory-made etcher was utilized to fabricate both the GRIN PC plate lens and the linear phononic waveguide on an 80 ?m thick AT-cut quartz plate. Interdigital transducers were fabricated directly on the quartz plate to generate the lowest anti-symmetric Lamb waves. A vibro-meter was used to detect the wave fields and the measured results on the focusing and waveguiding of the piezoelectric GRIN PC lens and waveguide are in good accordance with the numerical predictions. The results of this study may serve as a basis for developing an active micro plate lens and related devices. PMID:24909597

Chiou, Meng-Jhen; Lin, Yu-Ching; Ono, Takahito; Esashi, Masayoshi; Yeh, Sih-Ling; Wu, Tsung-Tsong

2014-09-01

379

Investigation and performance tests of a new parallel plate ionization chamber with double sensitive volume for measuring diagnostic X-rays  

NASA Astrophysics Data System (ADS)

Medical diagnostic equipment, like diagnostic radiology and mammography require a dosimeter with high accuracy for dosimetry of the diagnostic X-ray beam. Ionization chambers are suitable instruments for dosimetry of diagnostic-range X-ray beams because of their appropriate response and high reliability. This work introduces the design and fabrication of a new parallel plate ionization chamber with a PMMA body, graphite-coated PMMA windows (0.5 mm thick) and a graphite-foil central electrode (0.1 mm thick, 0.7 g/cm3 dense). This design improves upon the response characteristics of existing designs through the specific choice of materials as well as the appropriate size and arrangement of the ionization chamber components. The results of performance tests conducted at the Secondary Standard Dosimetry laboratory in Karaj-Iran demonstrated the short and long-term stability, the low leakage current, the low directional dependence, and the high ion collection efficiency of the design. Furthermore, the FLUKA Monte Carlo simulations confirmed the low effect of central electrode on this new ionization chamber response. The response characteristics of the parallel plate ionization chamber presented in this work makes the instrument suitable for use as a standard dosimeter in laboratories.

Sharifi, B.; Zamani Zeinali, H.; Soltani, J.; Negarestani, A.; Shahvar, A.

2015-01-01

380

Curved plate damper test and simulations with snubbers, through- flow, and flexible plate effects  

E-print Network

(Continued) F toi instantaneous dynamic radial force on the whole plate GN2 = gaseous nitrogen g(x, y) = normalized non-dimensional deflection shape function h = fluid film thickness, in. h, clearance, in. I(P) = functional for Reynold's equation IOD... . '&. Z = 28. 794 (X and YI Dta = 1. 752 0. 622 0. 5 0 2'I Dia =399 5. 192 0 5 0. 29 Dia = 4 g72 0 622 ~ Mid&lie probes, Z = 17. 137 (X anil YI 11. 523 ~ Calibration Pnihc 1. 5 I 3125 10 ~ Upper D. imper Probe&, Z = 6& 862 (X and Yl Damper...

Gadangi, Ravindra Kumar

2012-06-07

381

Brand Standards Brand StandardsBrand Standards  

E-print Network

Brand Standards 6.6.11 #12;Brand StandardsBrand Standards VISUAL IDENTITY AND BRANDING INITIATIVE, the signature building on the University/UMMC campus. The new brand identity provides a simplified & UMMC) and the public on May 12, 2011. #12;Brand StandardsBrand Standards Logos, marks, seals, colors

Weber, David J.

382

PLATE WAVE RESONANCE WITH AIR-COUPLED ULTRASONICS  

SciTech Connect

Air-coupled ultrasonic transducers can excite plate waves in metals and composites. The coincidence effect, i.e., the wave vector of plate wave coincides with projection of exciting airborne sound vector, leads to a resonance which strongly amplifies the sound transmission through the plate. The resonance depends on the angle of incidence and the frequency. In the present study, the incidence angle for maximum transmission (theta{sub max}) is measured in plates of steel, aluminum, carbon fiber reinforced composites and honeycomb sandwich panels. The variations of (theta{sub max}) with plate thickness are compared with theoretical values in steel, aluminum and quasi-isotropic carbon fiber composites. The enhanced transmission of air-coupled ultrasound at oblique incidence can substantially improve the probability of flaw detection in plates and especially in honeycomb structures. Experimental air-coupled ultrasonic scan of subtle flaws in CFRP laminates showed definite improvement of signal-to-noise ratio with oblique incidence at theta{sub max}.

Bar, H. N. [National Metallurgical Laboratory, Jamshedpur, India 831007 (India); Dayal, V.; Barnard, D.; Hsu, D. K. [Center for Nondestructive Evaluation, Iowa State University, Ames, IA 50011 (United States)

2010-02-22

383

Nonlinear analysis of piezoelectric nanocomposite energy harvesting plates  

NASA Astrophysics Data System (ADS)

This paper investigates the nonlinear analysis of energy harvesting from piezoelectric functionally graded carbon nanotube reinforced composite plates under combined thermal and mechanical loadings. The excitation, which derives from harmonically varying mechanical in-plane loading, results in parametric excitation. The governing equations of the piezoelectric functionally graded carbon nanotube reinforced composite plates are derived based on classical plate theory and von Krmn geometric nonlinearity. The material properties of the nanocomposite plate are assumed to be graded in the thickness direction. The single-walled carbon nanotubes (SWCNTs) are assumed to be aligned, straight and have a uniform layout. The linear buckling and vibration behavior of the nanocomposite plates is obtained in the first step. Then, Galerkins method is employed to derive the nonlinear governing equations of the problem with cubic nonlinearities associated with mid-plane stretching. Periodic solutions are determined by using the Poincar-Lindstedt perturbation scheme with movable simply supported boundary conditions. The effects of temperature change, the volume fraction and the distribution pattern of the SWCNTs on the parametric resonance, in particular the amplitude of vibration and the average harvested power of the smart functionally graded carbon nanotube reinforced composite plates, are investigated through a detailed parametric study.

Rafiee, M.; He, X. Q.; Liew, K. M.

2014-06-01

384

Optical waveguide spectrometer based on thin-film glass plates  

NASA Astrophysics Data System (ADS)

Commercially available thin-film glass plates have been successfully used for optical waveguide spectroscopy of chemical and biological films adsorbed upon the plates' surfaces. A 50-?m-thick glass plate was placed in contact with two parallel strips of silicone rubber supported on a slide glass. The plate area between the rubber strips served as the waveguiding region, eliminating the negative effect of the substrate on absorbance sensitivity. We coupled white light into the waveguide by focusing the light from a xenon lamp onto one end of a glass fiber and then inserting the other end into a glycerol drop overlaid upon the plate's surface. With a CCD detector, light at wavelengths as short as 360 nm was found to transmit out of the plate's end face. The propagation loss of the waveguide was measured to be <=1.2 dB/cm in the wavelength range 400-800 nm. A hemoglobin submonolayer equivalent to ~2% of a closely packed monolayer was detected with the sensor when the sensing path was 2 cm long.

Qi, Zhi-Mei; Matsuda, Naoki; Yoshida, Takamitsu; Asano, Hajime; Takatsu, Akiko; Kato, Kenji

2002-11-01

385

Electrochemical Machining of Metal Plates  

SciTech Connect

Electrochemical machining (ECM) with concentrated sodium chlorate electrolyte was used to rapidly cut a circular groove (13 cm diameter, 0.2 cm wide) through a 0.15 cm thick sheet of steel--thus opening a 5-inch porthole in as little as 10 minutes. The most favorable operating conditions were: T = 22 C; chlorate concentration 600 g NaClO{sub 3}/liter-solution; electric power of 100 A at 10 V; and flow of 0.5 l/s at a pressure drop of 10 kPa (1.5 psi). The porthole may be removed entirely by electrochemical means, or the electrochemical dissolution may continue until only thin membrane remains that is subsequently cut with a utility knife. An array of thermocouples was used to track temperature in the flowing solution and in the trough being machined; the maximum increase in temperature in the trough was 5 C over that of the flowing electrolyte which increased in temperature by 19 C because of power dissipation. ECM is shown feasible for rapid perforation of plates of ferrous and non-ferrous metals using portable equipment and commercial batteries. The technique can be extended to cut perforations of arbitrary shape through non-planar surfaces using a deformable ring cathode. Analysis of the power requirements for electrolyte flow and ECM indicate a total system weight of less than 45 kg (100 lb) using a commercial NiMH battery. The technique is recommended for reduction to practice and demonstration on full scale as an engineering prototype.

Cooper, J F; Evans, M C

2005-03-04

386

Improved Coal-Thickness Measurement  

NASA Technical Reports Server (NTRS)

Summed signals and dielectric-filled antenna improve measurement. Improved FM radar for measuring thickness of coal seam eliminates spectrum splitting and reduces magnitude of echo from front coal surface.

Barr, T. A.

1984-01-01

387

Tethered Triangular Plate  

NSDL National Science Digital Library

Simulation Software: Glotzer Group Code Simulation Method: Brownian Dynamics BD simulation of polymer tethered triangular plates. A system of building blocks of composition P10bT18b at a concentration of 0.20, was run starting at an effectively infinite temperature then instantaneously quenched to a temperature of 0.83. The system was then run for 12,000,000 time steps forming a hexagonally packing twisted columnar phase.The solve was favorable for the tethers. Simulation Model: United Atom Bead Spring with Lennard-Jones and FENE

Zhang, Zhenli

2005-01-31

388

Plates on the Move  

NSDL National Science Digital Library

In this activity, students create a model of sea floor spreading using two sheets of white paper and a metric ruler. The paper strips are pulled through a slit representing a mid-ocean ridge and divergent plate boundary. The model mimics how molten material rises to the surface and then spreads out in both directions. The resource is part of the teacher's guide accompanying the video, NASA SCI Files: The Case of the Shaky Quake. Lesson objectives supported by the video, additional resources, teaching tips and an answer sheet are included in the teacher's guide.

389

Plated wire memory subsystem  

NASA Technical Reports Server (NTRS)

The design, construction, and test history of a 4096 word by 18 bit random access NDRO Plated Wire Memory for use in conjunction with a spacecraft input/output and central processing unit is reported. A technical and functional description is given along with diagrams illustrating layout and systems operation. Test data is shown on the procedures and results of system level and memory stack testing, and hybrid circuit screening. A comparison of the most significant physical and performance characteristics of the memory unit versus the specified requirements is also included.

Carpenter, K. H.

1974-01-01

390

Plate Tectonics: Further Evidence  

NSDL National Science Digital Library

Early evidence showing striking similarities between regions on opposite sides of vast oceans suggested that in Earth's distant past what are now separate continents may once have been connected. However, this evidence said nothing about how the continents could have moved to their present positions. This video shows how seafloor spreading creates new oceanic crust and how the crust is destroyed by subduction into Earth's mantle, providing the mechanism and forces that propel tectonic plates across Earth's surface. The segment is two minutes nine seconds in length.

391

Earthquakes and Plate Tectonics  

NSDL National Science Digital Library

This activity, from the Real World Learning Objects Resource Library, allows students to use first-hand data analysis to "determine if there is any pattern to earthquake events and speculate on the causes of earthquakes." Intended to be an introductory activity for a unit of study on earthquakes, this 60-minute activity is complete with learning goals, step-by-step classroom procedures, materials, assessment activities, and resources for further information. The "Content Materials" section contains directions for students and graphics to help students understand earthquakes and plate tectonics. This is an excellent resource for geology and earth science instructors that is ready to use for the classroom.

2007-10-04

392

Dynamics of Tectonic Plates  

E-print Network

We suggest a model that describes a mutual dynamic of tectonic plates. The dynamic is a sort of stick-slip one which is modeled by a Markov random process. The process defines a microlevel of the dynamic. A macrolevel is obtained by a scaling limit which leads to a system of integro-differential equations which determines a kind of mean field systems. Conditions when Gutenberg-Richter empirical law are presented on the mean field level. These conditions are rather universal and do not depend on features of resistant forces.

Pechersky, E; Sadowski, G; Yambartsev, A

2014-01-01

393

High-temperature measurement using Cu-plating fiber Bragg grating for metal smart structure applications  

NASA Astrophysics Data System (ADS)

High-temperature experiments for electroless Cu-plating Fiber Bragg Grating (FBG) indicate that Cu-plating FBG can measure high-temperature up to (even beyond) 300C and it has high linearity, accuracy and repeatability. We can control Cu-plating FBG's temperature sensitivity by controlling plating layer's thickness. Temperature sensitivity of FBG with Cu-plating can be improved by more than three times with no less than 300?mthick coating by electroless and electrical Cu-plating. Such FBG can be soldered onto metal structures to get good bonding with the structure. As a result, such fiber sensors can get good protection, and high-temperature monitoring of smart structure is obtained.

Chang, Tianying; Jia, Lei; Sui, Qingmei; Cui, Hong-Liang

2014-03-01

394

A model of convergent plate margins based on the recent tectonics of Shikoku, Japan  

NASA Technical Reports Server (NTRS)

A viscoelastic finite element plate tectonic model is applied to displacement data for the island of Shikoku, Japan. The flow properties and geometry of the upper portions of the earth are assumed known from geophysical evidence, and the loading characteristics are determined from the model. The nature of the forces acting on the Philippine Sea plate, particularly in the vicinity of the Nankai trough, is determined. Seismic displacement data related to the 1946 Nankaido earthquake are modeled in terms of a thick elastic plate overlying a fluidlike substratum. The sequence of preseismic and seismic displacements can be explained in terms of two independent processes operating on elastic lithospheric plates: a strain accumulation process caused by vertical downward forces acting on or within the lithosphere in the vicinity of the trench, and a strain release process caused by plate failure along a preexisting zone on weakness. This is a restatement of Reid's elastic rebound theory in terms of elastic lithospheric plates.

Bischke, R. E.

1974-01-01

395

GEODVEL: Plate Motions From Space Geodesy  

NASA Astrophysics Data System (ADS)

We determine the relative angular velocities among eleven major plates using four space geodetic techniques. The data input consist of site motions estimated from 24 years of VLBI, 24 years of SLR, 14 years of GPS, and 12 years of DORIS data. We assign sites to plates on the basis of geology. We let sites move independently of plates if they are suspected of moving significantly due to isostatic adjustment to unloading of the late Pleistocene ice sheets. GEODVEL differs substantially from REVEL [Sella et al. 2002]. The 95% confidence limits in the GEODVEL angular velocities exclude REVEL for 19 of 21 plate pairs. The median angular velocity difference is 0.026 deg/Myr, which is 2.9 mm/yr. We will show that this difference is due partly to differences in the means by which the velocity of Earth's center is determined. (Sella et al. 2002 adopt ITRF19997; ITRF2000 differs from ITRF1997 by 2 mm/yr; we estimate the Earth center velocity to be near ITRF2000.) The relative angular velocities of seven plates are tightly constrained: North America, Eurasia, South America, Nubia, Pacific, Australia, and Antarctica. The three-dimensional standard error ellipsoids have principal semiaxes between 0.005 deg/Myr and 0.014 deg/Myr long; the one-dimensional 95% confidence limits are 0.6 to 1.8 mm/yr. We will compare GEODVEL against an updated set of angular velocities determined from seafloor spreading rates and transform azimuths.

Argus, D. F.; Gordon, R. G.; Ma, C.; Eanes, R. J.; Heflin, M. B.; Owen, S. E.; Willis, P.

2006-12-01

396

Prediction of high frequency gust response with airfoil thickness effects  

NASA Astrophysics Data System (ADS)

The unsteady lift forces that act on an airfoil in turbulent flow are an undesirable source of vibration and noise in many industrial applications. Methods to predict these forces have traditionally treated the airfoil as a flat plate. At higher frequencies, where the relevant turbulent length scales are comparable to the airfoil thickness, the flat plate approximation becomes invalid and results in overprediction of the unsteady force spectrum. This work provides an improved methodology for the prediction of the unsteady lift forces that accounts for the thickness of the airfoil. An analytical model was developed to calculate the response of the airfoil to high frequency gusts. The approach is based on a time-domain calculation with a sharp-edged gust and accounts for the distortion of the gust by the mean flow around the airfoil leading edge. The unsteady lift is calculated from a weighted integration of the gust vorticity, which makes the model relatively straightforward to implement and verify. For routine design calculations of turbulence-induced forces, a closed-form gust response thickness correction factor was developed for NACA 65 series airfoils.

Lysak, Peter D.; Capone, Dean E.; Jonson, Michael L.

2013-05-01

397

Plate tectonics on Venus  

NASA Technical Reports Server (NTRS)

The high surface temperature of Venus implies a permanently buoyant lithosphere and a thick basaltic crust. Terrestrial-style tectonics with deep subduction and crustal recycling is not possible. Overthickened basaltic crust partially melts instead of converting to eclogite. Because mantle magmas do not have convenient access to the surface the Ar-40 abundance in the atmosphere should be low. Venus may provide an analog to Archean tectonics on the earth.

Anderson, D. L.

1981-01-01

398

Plating on difficult-to-plate metals: what's new  

SciTech Connect

Some of the changes since 1970 in procedures for plating on such materials as titanium, molybdenum, silicon, aluminum, and gallium arsenide are summarized. While basic procedures for plating some of these materials were developed as many as 30 to 40 years ago, changes in the end uses of the plated products have necessitated new plating processes. In some cases, vacuum techniques - such as ion bombardment, ion implantation, and vacuum metallization - have been introduced to improve the adhesion of electrodeposits. In other cases, these techniques have been used to deposit materials upon which electrodeposits are required.

Wiesner, H.J.

1980-07-30

399

High accuracy wall thickness loss monitoring  

NASA Astrophysics Data System (ADS)

Ultrasonic inspection of wall thickness in pipes is a standard technique applied widely in the petrochemical industry. The potential precision of repeat measurements with permanently installed ultrasonic sensors however significantly surpasses that of handheld sensors as uncertainties associated with coupling fluids and positional offsets are eliminated. With permanently installed sensors the precise evaluation of very small wall loss rates becomes feasible in a matter of hours. The improved accuracy and speed of wall loss rate measurements can be used to evaluate and develop more effective mitigation strategies. This paper presents an overview of factors causing variability in the ultrasonic measurements which are then systematically addressed and an experimental setup with the best achievable stability based on these considerations is presented. In the experimental setup galvanic corrosion is used to induce predictable and very small wall thickness loss. Furthermore, it is shown that the experimental measurements can be used to assess the effect of reduced wall loss that is produced by the injection of corrosion inhibitor. The measurements show an estimated standard deviation of about 20nm, which in turn allows us to evaluate the effect and behaviour of corrosion inhibitors within less than an hour.

Gajdacsi, Attila; Cegla, Frederic

2014-02-01

400

75 FR 61699 - Stainless Steel Plate in Coils From Belgium, Italy, South Africa, South Korea, and Taiwan: Final...  

Federal Register 2010, 2011, 2012, 2013

...A-583-830] Stainless Steel Plate in Coils From Belgium, Italy, South Africa, South...duty orders on stainless steel plate in coils (SSPC) from Belgium, Italy, South Africa...and 4.75 mm or more in thickness, in coils, and annealed or otherwise heat...

2010-10-06

401

J. Acoustic Emission, 19 (2001) 258 2001 Acoustic Emission Group EFFECTS OF LATERAL PLATE DIMENSIONS ON ACOUSTIC EMISSION SIGNALS  

E-print Network

. The signals were filtered with either a 40-kHz high-pass filter or a 100-to-300-kHz bandpass filter. The AE-of-plane displacements corresponding to model sources of acoustic emission (AE) were calculated in aluminum plate samples-dipole located at different depths within the plate thickness. Analysis of the simulated AE signals shows

Hamstad, Marv

402

Numerical model of mixed convection heat transfer between a series of vertical parallel plates with planar heat sources  

E-print Network

. Independent parameters that were varied in this study included the buoyancy parameter (Gr/Re), the ratio of the plate conductivity to the fluid conductivity (K), and the ratio of the plate thickness to the channel width (W/B). The velocity profiles within...

Watson, James Christopher

2012-06-07

403

Visualization and thermal resistance measurement for the sintered mesh-wick evaporator in operating flat-plate heat pipes  

Microsoft Academic Search

This work presents visualization and measurement of the evaporation resistance for operating flat-plate heat pipes with sintered multi-layer copper-mesh wick. A glass plate was adopted as the top wall for visualization. The multi-layer copper-mesh wick was sintered on the copper bottom plate. With different combinations of 100 and 200 mesh screens, the wick thickness ranged from 0.26mm to 0.8mm. Uniform

Jhan-Hong Liou; Chia-Wei Chang; Chi Chao; Shwin-Chung Wong

2010-01-01

404

The science behind Plate Tectonics  

NSDL National Science Digital Library

Plate tectonics is a quantitative, robust and testable, geologic model describing the surface motions of Earth's outer skin. It is based on real data and assumptions, and built using the scientific method. New space geodesy data provide important quantitative (and independent) tests of this model. In general, these new data show a close match to model predictions, and suggest that plate motion is steady and uniform over millions of years. Active research continues to refine the model and to better our understanding of plate motion and tectonics. The exercise presented here aims to help students experience the process of doing science and to understand the science underlying the plate tectonic theory. Key words: plate tectonics, global plate motion models, assumptions, geologic data (spreading rates, transform fault azimuths, earthquake slip vectors), space geodesy tests.

Weber, John

405

Tectonics of the Easter plate  

NASA Technical Reports Server (NTRS)

A new model for the Easter plate is presented in which rift propagation has resulted in the formation of a rigid plate between the propagating and dying ridges. The distribution of earthquakes, eleven new focal mechanisms, and existing bathymetric and magnetic data are used to describe the tectonics of this area. Both the Easter-Nazca and Easter-Pacific Euler poles are sufficiently close to the Easter plate to cause rapid changes in rates and directions of motion along the boundaries. The east and west boundaries are propagating and dying ridges; the southwest boundary is a slow-spreading ridge and the northern boundary is a complex zone of convergent and transform motion. The Easter plate may reflect the tectonics of rift propagation on a large scale, where rigid plate tectonics requires boundary reorientation. Simple schematic models to illustrate the general features and processes which occur at plates resulting from large-scale rift propagation are used.

Engeln, J. F.; Stein, S.

1984-01-01

406

Study of gas tungsten arc welding procedures for tantalum alloy T-111 (Ta-8 W-2Hf) plate  

NASA Technical Reports Server (NTRS)

Methods of eliminating or reducing underbread cracking in multipass GTA welds in thick T-111 plate were studied. Single V butt welds prepared using experimental filler metal compositions and standard weld procedures resulted in only moderate success in reducing underbread cracking. Subsequent procedural changes incorporating manual welding, slower weld speeds, and three or fewer fill passes resulted in crack-free single V welds only when the filler metal was free of hafnium. The double V joint design with successive fill passes on opposite sides of the joint produced excellent welds. The quality of each weld was determined metallographically since the cracking, when present, was very slight and undetectable using standard NDT techniques. Tensile and bend tests were performed on selected weldments. The inherent filler metal strength and the joint geometry determined the strength of the weldment. Hardness and electron beam microprobe traverses were made on selected specimens with the result that significant filler metal-base metal dilution as well as hafnium segregation was detected. A tentative explanation of T-111 plate underbread cracking is presented based on the intrinsic effects of hafnium in the weldment.

Gold, R. E.; Kesterson, R. L.

1973-01-01

407

Standard methods for open hole tension testing of textile composites  

NASA Technical Reports Server (NTRS)

Sizing effects have been investigated by comparing the open hole failure strengths of each of the four different braided architectures as a function of specimen thickness, hole diameter, and the ratio of specimen width to hole diameter. The data used to make these comparisons was primarily generated by Boeing. Direct comparisons of Boeing's results were made with experiments conducted at West Virginia University whenever possible. Indirect comparisons were made with test results for other 2-D braids and 3-D weaves tested by Boeing and Lockheed. In general, failure strength was found to decrease with increasing plate thickness, increase with decreasing hole size, and decreasing with decreasing width to diameter ratio. The interpretation of the sensitive to each of these geometrical parameters was complicated by scatter in the test data. For open hole tension testing of textile composites, the use of standard testing practices employed by industry, such as ASTM D5766 - Standard Test Method for Open Hole Tensile Strength of Polymer Matrix Composite Laminates should provide adequate results for material comparisons studies.

Portanova, M. A.; Masters, J. E.

1995-01-01

408

Remote measurement of in-plane diffusivity components in plates  

NASA Technical Reports Server (NTRS)

A method of determining thermal diffusivity in thin plates is presented. The method, using infrared images of evolving thermal patterns previously injected with a laser, is noncontacting, one-sided, and remote. It does not require independent estimates of either the emissivity of the sample or the sample thickness. With a line-segment pattern for thermal input, it yields the inplane components of the diffusivity tensor in anisotropic materials and also the rate of heat loss to the environment of the plate. Two methods of data analysis are presented, one corresponding to a heating line of general cross section and the other considering a Gaussian cross section, thereby saving considerable computer time. Both methods produce a statistical evaluation of measurement quality as well as estimates of diffusivity and loss rate. Results are shown for plates of metals and graphite-epoxy composite materials. Principal components and orientation for the diffusivity tensor are obtained in the anisotropic graphite-epoxy sample.

Welch, Christopher S.; Heath, D. Michele; Winfree, William P.

1987-01-01

409

Excitations of thermoelastic waves in plates by a pulsed laser  

NASA Astrophysics Data System (ADS)

The method of the eigenfunction expansion, also known as the expansion in normal modes, is employed to study numerically the axisymmetric excitation of the thermoelastic waves in plates by a pulsed laser. This method gives a systematic treatment and allows one to investigate not only the quasistatic and dynamic thermoelastic responses of pulsed photothermal deformation on the time scale of 1 ?s, but also the thermoelastic generation of longitudinal, transverse, and surface acoustic waves in thick materials, as well as the excitations of the Rayleigh-Lamb wave modes in thin plates. The formalism is particularly suitable for waveform analyses of the excitations of transient Lamb waves in thin plates because one needs only to calculate the contributions of several lower eigenmodes. The numerical technique provides a quantitative tool for the experimental determination of material properties, especially the mechanical and elastic properties of free-standing films and thicker sheet materials by thermoelastic detection.

Cheng, J. C.; Zhang, S. Y.; Wu, L.

1995-09-01

410

Distribution of hydrogen in chromium-plated specimens  

SciTech Connect

The authors investigate the distribution of hydrogen in chromium-plated components and the way in which it is influenced by the individual operations of preliminary and subsequent treatments. It is shown that the hydrogen distribution has three zones with different concentrations and distributions of hydrogen. The hydrogen distribution in the specimens is influenced by surface hardening, by the temperature and the heat-treatment duration, and by thickness of the coating.

Zuev, B.K.; Kulakov, Y.A.; Kunin, L.L.; Mikhailova, G.V.; Sevast'yanov, V.S.; Timonina, O.K.

1985-07-01

411

Friction stir welding of 5052 aluminum alloy plates  

Microsoft Academic Search

Friction stir welding between 5052 aluminum alloy plates with a thickness of 2 mm was performed. The tool for welding was rotated at speeds ranging from 500 to 3?000 r\\/min under a constant traverse speed of 100 mm\\/min. The results show that at all tool rotation speeds, defect-free welds are successfully obtained. Especially at 1?000, 2?000 and 3?000 r\\/min, the

Yong-Jai KWON; Seong-Beom SHIM; Dong-Hwan PARK

2009-01-01

412

Spall behavior of rolled aluminum 5083-H116 plate  

NASA Astrophysics Data System (ADS)

The spall properties of rolled Al 5083-H116 plate are investigated using symmetric plate impact experiments over the stress range 1.5-6.2 GPa. Rear free surface velocity measurements made employing Velocity Interferometer System for Any Reflector interferometry reveal velocity profiles with clear signals of the Hugoniot elastic limit (HEL) and velocity pullback, indicative of a transition from elastic to plastic behavior and spalling. Experiments were performed on samples obtained both through the thickness and along all of the three principal axes of the rolled plate. For impact through the thickness, the average values of the HEL and spall strength are 0.43 GPa and 0.81 GPa, respectively. Decreasing the flyer plate and sample thicknesses resulted in an increased spall strength value of 0.95 GPa, while the HEL remained the same. The spall strength along the longitudinal (rolling) direction was 1.06 GPa versus 0.95 GPa for impact along either transverse direction. Spall damage for this impact direction often propagated away from the spall plane in the direction of impact and along the grain boundaries. For impact through the thickness, the fracture surface revealed a mixed mode of ductile and intergranular fracture that was not present for the fracture surface in the other two directions. This mixed fracture mode seems to correspond to a shoulder observed in the free surface velocity traces after the pullback. In all cases, cracked brittle inclusions were observed near the spall damage regions, indicating their role in nucleating voids during spall failure.

Whelchel, R. L.; Kennedy, G. B.; Dwivedi, S. K.; Sanders, T. H.; Thadhani, N. N.

2013-06-01

413

Performance of an inverted flat plate solar collector  

NASA Astrophysics Data System (ADS)

In this note an analysis of an inverted flat plate solar collector has been presented. Effect of various parameters, namely thickness of the insulation, air conductance between flowing water and top of the bottom insulation, length of the collector and flow velocity of water on the performance of the collector have been studied. Numerical calculations have been made for typical cold day in Delhi, namely 26 January 1980.

Tiwari, G. N.; Garg, H. P.; Husain, M. S.

1984-09-01

414

Global Topography and Tectonic Plates  

NSDL National Science Digital Library

The goal of this activity is to investigate global topographic and tectonic features, especially the tectonic plates and their boundaries. Using a double-page size digital topographic map of the Earth that includes both land and sea floor topography, students are asked to draw plate boundaries, deduce plate motions and interactions, and explore the connections between topography and tectonic processes at the global scale.

David Greene

415

Tectonic Plate Movements and Hotspots  

NSDL National Science Digital Library

This lesson introduces the idea that rates and directions of plate movements can be measured. The discussion centers on the use of mantle 'hotspots' to determine plate motions. Examples include the Hawaiian Islands, the Galapagos Islands, and the Yellowstone hotspot. The lesson includes an activity in which students use online resources to answer questions about the Galapagos Islands and measure plate movement rates using online data for the Hawaiian Islands hotspot.

Rhinehart, Ken

416

Plate T-11: Appalachian Mountains  

NSDL National Science Digital Library

Appalachian Mountain landforms clearly demonstrate the relation of plate tectonics and structure to geomorphology. The folded rocks record the convergence of two continental plates in Pennsylvanian/Permian time. This page uses text, maps, and remotely sensed imagery to explain the relationship between plate tectonics, geologic structures, and the resulting landforms. It is part of an out-of-print NASA publication entitled 'Geomorphology from Space'. Links to the rest of the book are provided.

417

Ion plating for the future  

NASA Technical Reports Server (NTRS)

The ion plating techniques are classified relative to the instrumental set up, evaporation media, and mode of transport. A distinction is drawn between the low vacuum (plasma) and high vacuum (ion beam) techniques. Ion plating technology is discussed at the fundamental and industrial level. At the fundamental level, the capabilities and limitations of the plasma (evaporant flux) and film characteristics are evaluated. And on the industrial level, the performance and potential uses of ion plated films are discussed.

Spalvins, T.

1981-01-01

418

Plane Wave Solutions and Modal Analysis in Higher Order Shear and Normal Deformable Plate Theories  

NASA Astrophysics Data System (ADS)

We use the three-dimensional Hellinger-Reissner mixed variational principle to derive a K th order (K = 0,1,2,...) shear and normal deformable plate theory. The balance laws, the constitutive relations and the boundary conditions for the plate theory are deduced. The constitutive relations incorporate the shear and the normal tractions applied on the top and the bottom surfaces of the plate. For a K th order plate theory with displacements expressed as a power series in the thickness co-ordinate z with terms up to z K, the transverse shear and the transverse normal stresses involve terms upto zK +2 while in-plane stress components have terms up to z K . The equations for the plate theory are expressed in a compact form by taking Legendre polynomials as the basis functions. The plate theory is used to study plane travelling waves and in particular the lengths of decay of the displacement components; this allows for a rigorous ordering of the importance of the displacement descriptors in terms of decaying properties.Finally, we study the free vibrations of a simply supported rectangular orthotropic thick plate; results from the present theory are compared with an exact three-dimensional solution and with other plate theories. To this end, a K th order compatible plate theory is also deduced; the term "compatible" alludes to the fact that the reduction map for the stress fields is induced by the kinematical reduction map, whilst in the "mixed" models it is postulated independently. It is found that the frequencies up to the fifth mode of vibration computed with the fifth order theory and without introducing any shear correction factors match very well with the corresponding analytical solution. Also, through-the-thickness distribution of all of the stress components is found to agree well with the three-dimensional elasticitysolution, while the stress distribution obtained from the compatible plate theories deviatesconsiderably, especially for the higher modes.

Batra, R. C.; Vidoli, S.; Vestroni, F.

2002-10-01

419

Glass-bead peen plating  

NASA Technical Reports Server (NTRS)

Peen plating of aluminum, copper, and nickel powders was investigated. Only aluminum was plated successfully within the range of peen plating conditions studied. Optimum plating conditions for aluminum were found to be: (1) bead/powder mixture containing 25 to 35% powder by weight, (2) peening intensity of 0.007A as measured by Almen strip, and (3) glass impact bead diameter of at least 297 microns (0.0117 inches) for depositing-100 mesh aluminum powder. No extensive cleaning or substrate preparation is required beyond removing loose dirt or heavy oil.

Graves, J. R.

1974-01-01

420

Carbon-assisted flyer plates  

DOEpatents

A laser driven flyer plate utilizing an optical fiber connected to a laser. The end of the optical fiber has a layer of carbon and a metal layer deposited onto it. The carbon layer provides the laser induced plasma which is superior to the plasma produced from most metals. The carbon layer plasma is capable of providing a flatter flyer plate, converting more of the laser energy to driving plasma, promoting a higher flyer plate acceleration, and providing a more uniform pulse behind the plate. In another embodiment, the laser is in optical communication with a substrate onto which a layer of carbon and a layer of metal have been deposited.

Stahl, David B. (Los Alamos, NM); Paisley, Dennis L. (Santa Fe, NM)

1994-01-01

421

True Shear Parallel Plate Viscometer  

NASA Technical Reports Server (NTRS)

This viscometer (which can also be used as a rheometer) is designed for use with liquids over a large temperature range. The device consists of horizontally disposed, similarly sized, parallel plates with a precisely known gap. The lower plate is driven laterally with a motor to apply shear to the liquid in the gap. The upper plate is freely suspended from a double-arm pendulum with a sufficiently long radius to reduce height variations during the swing to negligible levels. A sensitive load cell measures the shear force applied by the liquid to the upper plate. Viscosity is measured by taking the ratio of shear stress to shear rate.

Ethridge, Edwin; Kaukler, William

2010-01-01

422

Laser-driven flyer plate  

DOEpatents

Apparatus for producing high velocity flyer plates involving placing a layer of dielectric material between a first metal foil and a second metal foil. With laser irradiation through an optical substrate, the first metal foil forms a plasma in the area of the irradiation, between the substrate and the solid portion of the first metal foil. When the pressure between the substrate and the foil reaches the stress limit of the dielectric, the dielectric will break away and launch the flyer plate out of the second metal foil. The mass of the flyer plate is controlled, as no portion of the flyer plate is transformed into a plasma.

Paisley, Dennis L. (Santa Fe, NM)

1991-01-01

423

The Nature of Tectonic Plates  

NSDL National Science Digital Library

This lesson provides an overview of the various types of interactions between tectonic plates. The discussion uses the analogy of a cracked egg to describe the tectonic plates composing Earth's crust. Other topics include the concentrated earthquake and volcanic activity associated with plate boundaries, types of interactions at the boundaries, and how plate motions are affecting the Atlantic and Pacific Oceans. The lesson includes an activity in which students will use online references to locate a hypothetical nuclear power plant in a geologically safe area, investigate the history of large earthquakes in South Carolina, provide a likely location for a hypothetical geothermal power plant, and others.

Rhinehart, Ken

424

License Plates of the World  

NSDL National Science Digital Library

Whether you're interested in collecting license plates, or are just moving to Andorra and wonder what your car will be wearing when it gets there, this site provided by collector Michael Kustermann can be a handy reference. A winner in the "labor of love" website category, this frames-based directory contains pictures of and descriptive information about a dizzying range of automobile license plates, arranged geographically. Special issue and commemorative plates are also covered, as well as links to collector's clubs and a bibliography about the art and science of license plate hunting and gathering. You'll never look at bumpers quite the same way.

425

Finite element modelling of the flexural performance of resorbable phosphate glass fibre reinforced PLA composite bone plates.  

PubMed

A finite element method is presented to predict the flexural properties of resorbable phosphate glass fibre reinforced PLA composite bone plates. A novel method for meshing discontinuous fibre architectures is presented, which removes many of the limitations imposed by conventional finite element approaches. The model is used to understand the effects of increasing the span-to-thickness ratio for different fibre architectures used for PBG/PLA composites. A span-to-thickness ratio of 16:1 is found to be appropriate for materials with randomly orientated fibres, which agrees well with the test standard. However, for highly aligned materials the model indicates that a span-to-thickness ratio of 80:1 is required, in order to minimise the effects of shear deflection. The model is validated against flexural stiffness data from the literature for a range of polymers, fibres and fibre volume fractions. Generally there is less than 10% error between the FE predictions and experimental values. The model is subsequently used to perform a parametric study to understand what material developments are required to match the properties of PGF/PLA composites to cortical bone. It is concluded that alignment of the fibre is necessary to exceed the 20 GPa target, since the current manufacturing methods limit the fibre length to ?10 mm, which consequently restricts the flexural modulus to ?19 GPa (at 50% volume fraction). PMID:23022951

Harper, L T; Ahmed, I; Felfel, R M; Qian, C

2012-11-01

426

Sharp Lithosphere-asthenosphere Boundaries of Oceanic Plates  

NASA Astrophysics Data System (ADS)

P- and S-receiver function (RF) analysis of borehole broadband ocean bottom seismic data (Kumar et al., 2008, this meeting) and the high-resolution RF image of the subducting Pacific plate beneath the northeast Japan (Kawakatsu, 2008, this meeting) both show the presence of sharp lithosphere-asthenosphere boundaries (LABs) of oceanic plates which appear to show dependence on the plate age. The apparent plate-age dependence of the thickness of the oceanic plate is consistent with a thermally controlled origin for the oceanic LAB, but the fact it is observed in short period (~3s) indicates a sharp boundary (the transition thickness of less than 10-15km), thus a chemical or fabric origin. The observed amplitude of the LAB signals, on the other hand, requires a rather large S-wave speed reduction of ~7%, similar to the observation beneath the eastern North America (Rychert et al., 2007, JGR). One possibility to explain these features is the presence of partial melting in the asthenosphere. The depth of partial melting of the model of Mierdel et al. (2007, Science) estimated using a thermal model incorporating pressure and thermal effect on the thermal diffusivity (Honda&Yuen, 2001, GRL) reproduces the basic trend in the data. For a texturally equilibrated partially molten region, however, a 7% S-wave speed reduction translates into ~3.5% of melting (Takei, 2002, JGR) which may be unrealistically large. The presence of the rather strong LAB signal of oceanic plates reported here may be partly attributed to other mechanisms such as the presence of shear zone of partially-molten region in the asthenosphere (e.g., Holtzman et al., 2003, Science).

Kawakatsu, H.; Kumar, P.; Shinohara, M.; Kanazawa, T.; Araki, E.; Suyehiro, K.

2008-12-01

427

System for measuring film thickness  

DOEpatents

A system for determining the thicknesses of thin films of materials exhibiting fluorescence in response to exposure to excitation energy from a suitable source of such energy. A section of film is illuminated with a fixed level of excitation energy from a source such as an argon ion laser emitting blue-green light. The amount of fluorescent light produced by the film over a limited area within the section so illuminated is then measured using a detector such as a photomultiplier tube. Since the amount of fluorescent light produced is a function of the thicknesses of thin films, the thickness of a specific film can be determined by comparing the intensity of fluorescent light produced by this film with the intensity of light produced by similar films of known thicknesses in response to the same amount of excitation energy. The preferred embodiment of the invention uses fiber optic probes in measuring the thicknesses of oil films on the operational components of machinery which are ordinarily obscured from view.

Batishko, Charles R. (West Richland, WA); Kirihara, Leslie J. (Richland, WA); Peters, Timothy J. (Richland, WA); Rasmussen, Donald E. (Richland, WA)

1990-01-01

428

Buckling Analysis of Laminated Composite Plates Using Higher Order SemiAnalytical Finite Strip Method  

NASA Astrophysics Data System (ADS)

Rectangular plates made of laminated composite material because of the advantageously high strength and stiffness to weight ratio are used frequently as structural component in various branches of engineering, chief of which are aerospace and marine engineering. Design concepts of these plates that lead to the increase in the buckling load can directly lower the structural cost and/or weight. The finite strip method is one of a number of procedures which can be used to solve the buckling problem of plate structures. In the present work the main concern is with the buckling behavior of plates with simply supported ends subjected to uni-axial pure compression loads. The solution is sought by implementing the higher order semi-analytical finite strip method which incorporates additional degrees of freedom for each nodal line by using Reddys higher order plate theory. Therefore the current method is more universal in dealing with different plate thicknesses. In addition, in this semi-analytical finite strip method, all the displacements are postulated by the appropriate harmonic shape functions in the longitudinal direction and polynomial interpolation functions in the transverse direction. The solution is based on the concept of principle of minimum potential energy and an eigen-value analysis is subsequently carried out. From the presented results it can be concluded that the higher order semi-analytical finite strip method is very reliable for the preliminary design of composite plates especially in the case of buckling analysis of relatively thick plates.

Ovesy, Hamid R.; Ghannadpour, Sayyed Amir M.; Sherafat, Mohammad H.

2010-04-01

429

Downgoing plate controls on overriding plate deformation in subduction zones  

NASA Astrophysics Data System (ADS)

Although subduction zones are convergent margins, deformation in the upper plate can be extensional or compressional and tends to change through time, sometimes in repeated episodes of strong deformation, e.g, phases of back-arc extension. It is not well understood what factors control this upper plate deformation. We use the code Fluidity, which uses an adaptive mesh and a free-surface formulation, to model a two-plate subduction system in 2-D. The model includes a composite temperature- and stress-dependent rheology, and plates are decoupled by a weak layer, which allows for free trench motion. We investigate the evolution of the state of stress and topography of the overriding plate during the different phases of the subduction process: onset of subduction, free-fall sinking in the upper mantle and interaction of the slab with the transition zone, here represented by a viscosity contrast between upper and lower mantle. We focus on (i) how overriding plate deformation varies with subducting plate age; (ii) how spontaneous and episodic back-arc spreading develops for some subduction settings; (iii) the correlation between overriding plate deformation and slab interaction with the transition zone; (iv) whether these trends resemble observations on Earth.

Garel, Fanny; Davies, Rhodri; Goes, Saskia; Davies, Huw; Kramer, Stephan; Wilson, Cian

2014-05-01

430

Lithosphere thickness variation along the Eastern Alps  

NASA Astrophysics Data System (ADS)

Analysis of Ps and Sp receiver functions from datasets collected by permanent and temporary seismic stations, image lithospheric discontinuities across the entire Eastern Alps with tens of kilometers lateral resolution. The receiver functions show the presence of a discontinuity within the upper mantle that is due to a negative velocity contrast. The comparison with other geophysical observations renders it likely that the observed discontinuity represents the lithosphere-asthenosphere boundary. This sheds light on the formation and evolution of the Eastern Alps, being a result of long-term convergence between the European and Adriatic plates and of the lateral (east directed) tectonic extrusion associated with the retreating subduction of the nearby Carpathian slab. The lateral variations in lithosphere thickness mirror these two processes and both mechanisms are reflected in the structure we image with the lithospheric discontinuities. For the first time in the area the Lithosphere-Asthenosphere Boundary is imaged with such a clear depth variation, reflecting the depth extent of the dextral extrusion of the EA towards the Pannonian Basin.

Bianchi, Irene; Miller, Meghan S.; Bokelmann, Gtz

2014-05-01

431

Automatic plate measurement  

NASA Astrophysics Data System (ADS)

A working model of an automatic device for measuring astronomical plates has been developed and built which performs the functions of photometry and image diameter and coordinate determination. The model consists of a system for obtaining an accurate position, a scanner and a small computer, and is capable of operating in the automatic and semiautomatic modes. The image coordinates for a point object may be determined with an rms error of less than 1 micron, with an average time for object search and measurement of 20-30 sec. Measurements of the phases of the asteroid 39 Laetitia have demonstrated that the instrument is capable of measurements with precisions exceeding those in present star catalogs. The instrument is thus suitable for the automatic preparation of photographic reference star catalogs.

Rizvanov, N. G.; Sergeev, A. V.

1981-02-01

432

Plate Tectonics: Earthquake Epicenter  

NSDL National Science Digital Library

This lesson provides an overview of destructive earthquakes and their connection to tectonic movements of the Earth's crust. It includes a discussion of some especially destructive historic earthquakes, and a brief introduction to contintental drift and the theory of plate tectonics. There is also discussion of basic seismology (types of waves) and measures of the magnitude of an earthquake (the Richter Scale). The lesson inlcudes an activity in which students use an online simulator to locate the epicenter of an earthquake using readings from three different seismograph stations. After they have completed the simulation, they attempt to locate the epicenter of a real earthquake using data from the United States Geological Survey (USGS) earthquake website.

Pratte, John

433

Intermittent plate tectonics?  

PubMed

Although it is commonly assumed that subduction has operated continuously on Earth without interruption, subduction zones are routinely terminated by ocean closure and supercontinent assembly. Under certain circumstances, this could lead to a dramatic loss of subduction, globally. Closure of a Pacific-type basin, for example, would eliminate most subduction, unless this loss were compensated for by comparable subduction initiation elsewhere. Given the evidence for Pacific-type closure in Earth's past, the absence of a direct mechanism for termination/initiation compensation, and recent data supporting a minimum in subduction flux in the Mesoproterozoic, we hypothesize that dramatic reductions or temporary cessations of subduction have occurred in Earth's history. Such deviations in the continuity of plate tectonics have important consequences for Earth's thermal and continental evolution. PMID:18174440

Silver, Paul G; Behn, Mark D

2008-01-01

434

Phase contrast without phase plates and phase rings--optical solutions for improved imaging of phase structures.  

PubMed

Using the optical methods described, phase specimens can be observed with a modified light microscope in enhanced clarity, purified from typical artifacts which are apparent in standard phase contrast illumination. In particular, haloing and shade-off are absent, lateral and vertical resolution are maximized and the image quality remains constant even in problematic preparations which cannot be well examined in normal phase contrast, such as specimens beyond a critical thickness or covered by obliquely situated cover slips. The background brightness and thus the range of contrast can be continuously modulated and specimens can be illuminated in concentric-peripheral, axial or paraxial light. Additional contrast effects can be achieved by spectral color separation. Normal glass or mirror lenses can be used; they do not need to be fitted with a phase plate or a phase ring. The methods described should be of general interest for all disciplines using phase microscopy. PMID:23913620

Piper, Timm; Piper, Jrg

2013-10-01

435

Assessment of marginal bone loss using full thickness versus partial thickness flaps for alveolar ridge splitting and immediate implant placement in the anterior maxilla.  

PubMed

The aim of this study was to evaluate the effectiveness of maintaining the periosteal attachment of the facial and palatal cortical plates on crestal bone loss that occurs at the margin of dental implants placed immediately in split anterior maxillary alveolar ridges. This was a prospective randomized comparative clinical trial. The study population included 22 patients with edentulous anterior maxillary alveolar ridges who presented for treatment during the period March 2012 to September 2013. The selected patients were divided randomly into two equal groups. All patients underwent a maxillary ridge splitting technique; a total of 43 implants were placed immediately. A full thickness mucoperiosteal flap was performed in the control group patients, while a split thickness mucosal flap was done in the study group patients. Assessments included measurements of the linear changes in the marginal bone surrounding the implants immediately postoperative and after 6 months. Measurements were taken from cross-sectional and longitudinal cone beam computed tomography images using special software. The partial thickness flap used in the study group decreased the percentage of bone loss by 9.5% for the labial bone plate, 7.9% for the palatal bone plate, and 3.5% for the mesiodistal bone plate. PMID:24973295

Mounir, M; Beheiri, G; El-Beialy, W

2014-11-01

436

DAMAGE LOCATION IN THICK COMPOSITE MATERIAL BASED ON ACOUSTIC EMISSION AND WIRELESS NODES  

E-print Network

rechargeable batteries. The set of experiments were based on a composite plate containing two TDAMAGE LOCATION IN THICK COMPOSITE MATERIAL BASED ON ACOUSTIC EMISSION AND WIRELESS NODES as the feasibility to use such technology for impact location. KEYWORDS : acoustic emission, composite, damage

Boyer, Edmond

437

Analysis of tongue and groove joints for thick laminatesq Karel Matous, George J. Dvorak*  

E-print Network

Received 19 September 2003; accepted 11 January 2004 Available online 9 June 2004 Abstract A finite element 2. Then, Section 3 explains the finite element solution procedure used in solving specific problems of a homogenized thick composite laminate to steel plate. The quasi-isotropic laminate is made of glass fabric

Matous, Karel

438

Fatigue crack detection in thick steel structures with piezoelectric wafer active sensors  

Microsoft Academic Search

This paper presents a set of numerical and experimental results on the use of guided waves for structural health monitoring (SHM) of crack growth during a fatigue test in a thick steel plate used for civil engineering application. The capability of embedded piezoelectric wafer active sensors (PWAS) to perform in situ nondestructive evaluation (NDE) is explored. Numerical simulation and experimental

M. Gresil; L. Yu; V. Giurgiutiu

2011-01-01

439

Fermion localization on thick branes  

SciTech Connect

We consider chiral fermion confinement in scalar thick branes, which are known to localize gravity, coupled through a Yukawa term. The conditions for the confinement and their behavior in the thin-wall limit are found for various different BPS branes, including double walls and branes interpolating between different AdS{sub 5} spacetimes. We show that only one massless chiral mode is localized in all these walls, whenever the wall thickness is keep finite. We also show that, independently of wall's thickness, chiral fermionic modes cannot be localized in dS{sub 4} walls embedded in a M{sub 5} spacetime. Finally, massive fermions in double wall spacetimes are also investigated. We find that, besides the massless chiral mode localization, these double walls support quasilocalized massive modes of both chiralities.

Melfo, Alejandra; Pantoja, Nelson [Centro de Fisica Fundamental, Universidad de Los Andes, Merida (Venezuela); Tempo, Jose David [Centro de Fisica Fundamental, Universidad de Los Andes, Merida (Venezuela); Centro de Estudios Cientificos CECS, Casilla 1469, Valdivia (Chile)

2006-02-15

440

Plate tectonics, damage and inheritance  

NASA Astrophysics Data System (ADS)

The initiation of plate tectonics on Earth is a critical event in our planet's history. The time lag between the first proto-subduction (about 4 billion years ago) and global tectonics (approximately 3 billion years ago) suggests that plates and plate boundaries became widespread over a period of 1 billion years. The reason for this time lag is unknown but fundamental to understanding the origin of plate tectonics. Here we suggest that when sufficient lithospheric damage (which promotes shear localization and long-lived weak zones) combines with transient mantle flow and migrating proto-subduction, it leads to the accumulation of weak plate boundaries and eventually to fully formed tectonic plates driven by subduction alone. We simulate this process using a grain evolution and damage mechanism with a composite rheology (which is compatible with field and laboratory observations of polycrystalline rocks), coupled to an idealized model of pressure-driven lithospheric flow in which a low-pressure zone is equivalent to the suction of convective downwellings. In the simplest case, for Earth-like conditions, a few successive rotations of the driving pressure field yield relic damaged weak zones that are inherited by the lithospheric flow to form a nearly perfect plate, with passive spreading and strike-slip margins that persist and localize further, even though flow is driven only by subduction. But for hotter surface conditions, such as those on Venus, accumulation and inheritance of damage is negligible; hence only subduction zones survive and plate tectonics does not spread, which corresponds to observations. After plates have developed, continued changes in driving forces, combined with inherited damage and weak zones, promote increased tectonic complexity, such as oblique subduction, strike-slip boundaries that are subparallel to plate motion, and spalling of minor plates.

Bercovici, David; Ricard, Yanick

2014-04-01

441

Plate tectonics, damage and inheritance.  

PubMed

The initiation of plate tectonics on Earth is a critical event in our planet's history. The time lag between the first proto-subduction (about 4?billion years ago) and global tectonics (approximately 3?billion years ago) suggests that plates and plate boundaries became widespread over a period of 1?billion years. The reason for this time lag is unknown but fundamental to understanding the origin of plate tectonics. Here we suggest that when sufficient lithospheric damage (which promotes shear localization and long-lived weak zones) combines with transient mantle flow and migrating proto-subduction, it leads to the accumulation of weak plate boundaries and eventually to fully formed tectonic plates driven by subduction alone. We simulate this process using a grain evolution and damage mechanism with a composite rheology (which is compatible with field and laboratory observations of polycrystalline rocks), coupled to an idealized model of pressure-driven lithospheric flow in which a low-pressure zone is equivalent to the suction of convective downwellings. In the simplest case, for Earth-like conditions, a few successive rotations of the driving pressure field yield relic damaged weak zones that are inherited by the lithospheric flow to form a nearly perfect plate, with passive spreading and strike-slip margins that persist and localize further, even though flow is driven only by subduction. But for hotter surface conditions, such as those on Venus, accumulation and inheritance of damage is negligible; hence only subduction zones survive and plate tectonics does not spread, which corresponds to observations. After plates have developed, continued changes in driving forces, combined with inherited damage and weak zones, promote increased tectonic complexity, such as oblique subduction, strike-slip boundaries that are subparallel to plate motion, and spalling of minor plates. PMID:24717430

Bercovici, David; Ricard, Yanick

2014-04-24

442

Relative motions of the Australian, Pacific and Antarctic plates estimated by the Global Positioning System  

NASA Technical Reports Server (NTRS)

Global Positioning System (GPS) measurements spanning approximately 3 years have been used to determine velocities for 7 sites on the Australian, Pacific and Antarctic plates. The site velocities agree with both plate model predictions and other space geodetic techniques. We find no evidence for internal deformation of the interior of the Australian plate. Wellington, New Zealand, located in the Australian-Pacific plate boundary zone, moves 20 +/- 5 mm/yr west-southwest relative to the Australian plate. Its velocity lies midway between the predicted velocities of the two plates. Relative Euler vectors for the Australia-Antarctica and Pacific-Antarctica plates agree within one standard deviation with the NUVEL-1A predictions.

Larson, Kristine M.; Freymueller, Jeff

1995-01-01

443

Non contact probing of interfacial stiffnesses between two plates by zero-group velocity Lamb modes  

NASA Astrophysics Data System (ADS)

A non contact technique using zero-group velocity (ZGV) Lamb modes is developed to probe the bonding between two solid plates coupled by a thin layer. The layer thickness is assumed to be negligible compared with the plate thickness and the acoustic wavelength. The coupling layer is modeled by a normal and a tangential spring to take into account the normal and shear interfacial stresses. Theoretical ZGV frequencies are determined for a symmetrical bi-layer structure and the effect of the interfacial stiffnesses on the cut-off and ZGV frequencies are evaluated. Experiments are conducted with two glass plates bonded by a drop of water, oil, or salol, leading to a few micrometer thick layer. An evaluation of normal and shear stiffnesses is obtained using ZGV resonances locally excited and detected with laser ultrasonic techniques.

Mezil, Sylvain; Laurent, Jrme; Royer, Daniel; Prada, Claire

2014-07-01

444

Measurements of displacement around holes in composite plates subjected to quasi-static compression  

NASA Technical Reports Server (NTRS)

Attempts to develop a whole-field, high sensitivity optical technque for measurement of load induced changes of thickness of composite plates are described. Graphite-epoxy plates of quasi-isotropic layup were used as test specimens. Changes of thickness of three plates, each with a central hole of different size, were measured as a function of applied compressive loads. The first test specimen showed localized zones where no holographic fringes were present, surrounded by zones of low fringe contrast. This was thought to be a result of localized motion or creep. Subsequent tests with an increased time interval between specimen loading and holographic exposure demonstrated no localized zones of absent fringes. No plausible explanation for radical differences in the quality of fringe patterns was found, although the use of specimens having a high quality mirrorized surface provided superior change of thickness patterns. Recommendations for further investigations and changes in test procedure are presented.

Duke, J. C., Jr.; Post, D.; Czarnek, R.; Asundi, A.

1982-01-01

445

How Thick is Your Hair?  

NSDL National Science Digital Library

In this activity on page 13 of the PDF, learners use a laser pointer (with known wavelength of light) to measure the thickness of a human hair. By shining the laser on a hair, analyzing the patterns created, and completing some calculations, learners the thickness of a hair in nanometers. Learners can calibrate the laser to find its wavelength by completing the first activity in the manual entitled, "Spots, Lines and Lasers." This manual contains 4 activities related to the Spectra: The Original Laser Superhero Force comic book published by the American Physical Society.

Thompson-Flagg, Rebecca; Johnson, Kerry G.

2010-01-01

446

Monitoring deterioration of waffle cooler thickness at Polokwane Smelter  

NASA Astrophysics Data System (ADS)

Cooling elements in operating furnaces, such as waffle coolers, finger coolers, cooling staves, and plate coolers, are subject to wearing and deterioration over time. Ultrasonic (UT) pulse echo is an efficient nondestructive testing methodology to monitor the thickness and quality of the cooling blocks through periodical inspections; however, the highly dampening properties of copper and the high temperatures on the hot face of the cooling elements could cause errors in UT thickness measurements. To eliminate potential errors in UT measurements, a study was conducted to determine the correct temperature and velocity distributions and relationship in waffle coolers. In this study, a combination of mathematical modeling and experimental work was used to establish a relationship between the temperature and the speed of ultrasonic waves in copper elements.

Sadri, Afshin; Gebski, Pawel; Ghorbani, Hamid; McGarrie, Gordon; de Vries, Tamryn

2009-10-01

447

Wind-tunnel simulation of thick turbulent boundary layer  

NASA Astrophysics Data System (ADS)

An experimental study aimed at revealing the possibility of simulation, in a subsonic wind tunnel, of enhanced Reynolds numbers Re** via modeling a thick flat-plate boundary layer possessing the properties of a Clauser-equilibrium shear flow is reported. We show that turbulators prepared in the form of variable-height cylinders of height h and diameter d = 3 mm and installed in two rows along the normal to the streamlined wall offer rather an efficient means for modification of turbulent boundary layer in solving the problem. In the majority of cases, mean and fluctuating characteristics of the boundary layer exhibit values typical of naturally developing turbulent boundary layers at a distance of 530 cylinder diameters. The profiles of mean velocity with artificially enhanced boundary-layer thickness can be well approximated, in the law-of-the-wall variables, with the well-known distribution of velocities for canonical boundary layer.

Kornilov, V. I.; Boiko, A. V.

2012-06-01

448

A New Electromagnetic Instrument for Thickness Gauging of Conductive Materials  

NASA Technical Reports Server (NTRS)

Eddy current techniques are widely used to measure the thickness of electrically conducting materials. The approach, however, requires an extensive set of calibration standards and can be quite time consuming to set up and perform. Recently, an electromagnetic sensor was developed which eliminates the need for impedance measurements. The ability to monitor the magnitude of a voltage output independent of the phase enables the use of extremely simple instrumentation. Using this new sensor a portable hand-held instrument was developed. The device makes single point measurements of the thickness of nonferromagnetic conductive materials. The technique utilized by this instrument requires calibration with two samples of known thicknesses that are representative of the upper and lower thickness values to be measured. The accuracy of the instrument depends upon the calibration range, with a larger range giving a larger error. The measured thicknesses are typically within 2-3% of the calibration range (the difference between the thin and thick sample) of their actual values. In this paper the design, operational and performance characteristics of the instrument along with a detailed description of the thickness gauging algorithm used in the device are presented.

Fulton, J. P.; Wincheski, B.; Nath, S.; Reilly, J.; Namkung, M.

1994-01-01

449

Bladder Wall Thickness Mapping for Magnetic Resonance Cystography  

PubMed Central

Clinical studies have shown the evidence that the bladder wall thickness is an effective biomarker for bladder abnormalities. The clinical optical cystoscopy, the current gold standard, cannot show the wall thickness. The use of ultrasound by experts may generate some local thickness information, but the information is limited in field-of-view and is user dependent. Recent advances in magnetic resonance (MR) imaging technologies lead MR-based virtual cystoscopy or MR cystography toward a potential alternative to map the wall thickness for the entire bladder. From a high resolution structural MR volumetric image of the abdomen, a reasonable segmentation of the inner and outer borders of the bladder wall can be achievable. Starting from here, this paper reviews the limitation of a previous distance field-based approach of measuring the thickness between the two borders and then provides a solution to overcome the limitation by an electric field-based strategy. In addition, this paper further investigates a surface fitting strategy to minimize the discretization errors on the voxel-like borders and facilitate the thickness mapping on the three-dimensional patient-specific bladder model. The presented thickness calculation and mapping were tested on both phantom and human subject datasets. The results are preliminary but very promising with a noticeable improvement over the previous distance field-based approach. PMID:23835844

Zhao, Yang; Liang, Zhengrong; Zhu, Hongbin; Han, Hao; Duan, Chaijie; Yan, Zengmin; Lu, Hongbing; Gu, Xianfeng

2013-01-01

450

Plate Borders and Mountain Building  

NSDL National Science Digital Library

This page features animations of four different types of plate boundaries, including one animation of the collision of two pieces of continental crust, forming steep mountain ranges. The animations are all presented in flash, and the plate convergence offers a useful, generic view of orogeny.

Schlumberger Excellence in Educational Development, Inc.

451

Anodic aluminum oxide microchannel plates  

Microsoft Academic Search

A new material for microchannel plates (MCP) is proposed anodic aluminum oxide. Microchannel plates made of this material may be much cheaper than with conventional lead glass MCP. Also a significantly smaller channel diameter (up to 70nm) is easily achievable, which means better spatial resolution and the possibility to operate in strong magnetic fields. Methods and means are developed

A. Govyadinov; I. Emeliantchik; A. Kurilin

1998-01-01

452

Earthquakes, Volcanoes, and Plate Tectonics  

NSDL National Science Digital Library

This page consists of two maps of the world, showing how earthquakes define the boundaries of tectonic plates. Volcanoes are also distributed at plate boundaries (the "Ring of Fire" in the Pacific) and at oceanic ridges. It is part of the U.S. Geological Survey's Cascades Volcano Observatory website, which features written material, images, maps, and links to related topics.

453

Plate Tectonics: Recycling the Seafloor  

NSDL National Science Digital Library

In this activity, learners work in teams to predict and outline the location of plate boundaries using the National Oceanic and Atmospheric Administration's Acoustic Monitoring Program's underwater earthquake data. Then, learners compare their estimates to the USGS's map of the plates and discuss.

Lawrence, Lisa A.

2012-12-27

454

Global Curvature, Thickness, and the Ideal Shapes of Knots  

Microsoft Academic Search

The global radius of curvature of a space curve is introduced. This function is related to, but distinct from, the standard local radius of curvature and is connected to various physically appealing properties of a curve. In particular, the global radius of curvature function provides a concise characterization of the thickness of a curve, and of certain ideal shapes of

Oscar Gonzalez; John H. Maddocks

1999-01-01

455

Effect of thickness variation on collapse pressure of seamless pipes  

Microsoft Academic Search

The present paper is concerned with determining the effect of thickness variation on collapse pressure of seamless pipes. There exists extensive information on the effects external pressure has on pipelines. A substantial amount of literature deals with results of analysis, numerical modelling and testing of pipes those are gradually subject to external pressure. This knowledge has been incorporated into standards

Fuat Kara; Josef Navarro; Robert L. Allwood

2010-01-01

456

Global Plate Velocities from the Global Positioning System  

NASA Technical Reports Server (NTRS)

We have analyzed 204 days of Global Positioning System (GPS) data from the global GPS network spanning January 1991 through March 1996. On the basis of these GPS coordinate solutions, we have estimated velocities for 38 sites, mostly located on the interiors of the Africa, Antarctica, Australia, Eurasia, Nazca, North America, Pacific, and South America plates. The uncertainties of the horizontal velocity components range from 1.2 to 5.0 mm/yr. With the exception of sites on the Pacific and Nazca plates, the GPS velocities agree with absolute plate model predictions within 95% confidence. For most of the sites in North America, Antarctica, and Eurasia, the agreement is better than 2 mm/yr. We find no persuasive evidence for significant vertical motions (less than 3 standard deviations), except at four sites. Three of these four were sites constrained to geodetic reference frame velocities. The GPS velocities were then used to estimate angular velocities for eight tectonic plates. Absolute angular velocities derived from the GPS data agree with the no net rotation (NNR) NUVEL-1A model within 95% confidence except for the Pacific plate. Our pole of rotation for the Pacific plate lies 11.5 deg west of the NNR NUVEL-1A pole, with an angular speed 10% faster. Our relative angular velocities agree with NUVEL-1A except for some involving the Pacific plate. While our Pacific-North America angular velocity differs significantly from NUVEL-1A, our model and NUVEL-1A predict very small differences in relative motion along the Pacific-North America plate boundary itself. Our Pacific-Australia and Pacific- Eurasia angular velocities are significantly faster than NUVEL-1A, predicting more rapid convergence at these two plate boundaries. Along the East Pacific Pise, our Pacific-Nazca angular velocity agrees in both rate and azimuth with NUVFL-1A.

Larson, Kristine M.; Freymueller, Jeffrey T.; Philipsen, Steven

1997-01-01

457

Small deflection of a class of clamped thin plates using collocation  

NASA Technical Reports Server (NTRS)

Equations are given for the optimization of a class of two-and three-dimensional structures. The application of existing analytical techniques to the response of thin clamped plates is described. The ratios of deflections to plate thickness are given for uniform transverse loads as well as for uniform plus linearly varying transverse loads. Deflections are presented at angular increments of 5 degrees and at radial increments of 0.1 of the radius.

Worley, W. J.

1977-01-01

458

High electric fields and surface layers in very thin single crystal plates of triglycine sulfate  

Microsoft Academic Search

We have recently seen drastic changes of electrical properties in newly available very thin single crystal plates of triglycine sulfate. They can be considered as arising from a high internal field (1 MV\\/m in a 1 ?m thick plate cut perpendicular to the axis, electrodes short circuited).This electric field is explained in a new phenomenological surface-layer model where spontaneous polarization

A. Hadni; R. Thomas

1984-01-01

459

Flexural analysis of laminated composites using refined higher-order C plate bending elements  

Microsoft Academic Search

A finite element formulation for flexure of a symmetrically laminated plate based on a higher-order displacement model and a three-dimensional state of stress and strain is presented here. The present higher-order theory incorporates linear variation of transverse normal strains and parabolic variation of transverse shear strains through the plate thickness, and as a result it does not require shear correction

B. N. PANDYA; Tarun KANT

1988-01-01

460

How Mantle Slabs Drive Plate Tectonics  

Microsoft Academic Search

The gravitational pull of subducted slabs is thought to drive the motions of Earth's tectonic plates, but the coupling between slabs and plates is not well established. If a slab is mechanically attached to a subducting plate, it can exert a direct pull on the plate. Alternatively, a detached slab may drive a plate by exciting flow in the mantle

Clinton P. Conrad; Carolina Lithgow-Bertelloni

2002-01-01

461

Lens (thick lens) and mirror  

NSDL National Science Digital Library

This applet allows the user to make a lens or a mirror and observe its effect on distant light. The user can change the thickness, the curvatures, the diameter, the index of refraction of the lens, and the index of refraction of the surrounding medium. Several special cases are pre-programmed and can be invoked by clicking on a link.

Hwang, Fu-Kwun

2008-12-27

462

Convergent plate margin east of North Island, New Zealand  

SciTech Connect

The Indian-Pacific plate boundary passes along the eastern margin of North Island, New Zealand, with the Pacific plate being thrust under the Indian plate to the west. The continental slope forming the Indian plate margin is broad with a well-formed series of trench slope basins and intervening ridges along the continental slope and shelf, subparallel to the margin, and continuing onto land. Multichannel seismic reflection data recorded across this margin show a thick (2.5-km) sedimentary section overlying oceanic basement in the deep-water part of the profile, and part of this sedimentary section is apparently being subducted under the accretionary prism. At the toe of the continental slope, nascent thrusts, often showing little apparent offset but a change in reflection amplitude, occur over a broad region. Well-defined trench slope basins show several episodes of basin formation and thrusting and are similar to structural interpretations for adjacent onshore basins. A bottom simulating reflector, which may delineate a gas-hydrate layer, can be traced over the midslope part of the profile. A major reflector, interpreted as the base of the accretionary prism, can be traced discontinuously to the coast where it coincides with the top of a zone of high seismicity, considered to mark the top of the subducted Pacific plate.

Davey, F.J; Hampton, M.; Lewis, K.

1986-07-01

463

Plate tectonics, damage and inheritance  

NASA Astrophysics Data System (ADS)

The initiation of plate tectonics on Earth is a critical event in our planet's history. The time lag between the first proto subduction about 4Ga, evident in geochemical analysis from ancient cratons, to global tectonics by 3-2.7Ga, suggests that plates and plate boundaries spread globally over a 1Gyr period. We hypothesize that when sufficient lithospheric damage, which promotes shear-localization and long-lived weak zones, combines with transient mantle flow and migrating proto-subduction, it leads to the accumulation of plate boundaries and eventually fully formed tectonic plates driven by subduction alone. We demonstrate this process with an idealized model of pressure-driven flow (wherein a low pressure zone is equivalent to downwelling suction or slab pull) in a lithosphere that self-weakens according to a mylonitic-type polycrystalline grain-damage mechanism (Bercovici and Ricard, Phys. Earth Planet. Int. v.202-203, pp27-55, 2012). In the simplest case, for Earth-like conditions, four successive orthogonal rotations of the driving pressure field yield relic damage