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1

Turbulent flow characteristics in circular corrugated culverts at mild slopes  

Microsoft Academic Search

Anthropogenic barriers to fish passage at stream crossings are an important issue in North America. Environmental regulations impose velocity restrictions on culvert flow, which may be overly simplistic. A series of laboratory experiments were conducted in a corrugated metal pipe culvert at three mild slopes. Acoustic Doppler velocimeters were used to measure velocity and turbulence quantities. A significant percentage of

Shawn P. Clark; Nicholas Kehler

2011-01-01

2

Structural Analysis of Corrugated Metal Box-Type Culverts.  

National Technical Information Service (NTIS)

In the study, field performance of a rib-corrugated aluminum, a rib-corrugated steel, a plate-corrugated steel, and a deep corrugated steel box-type culverts, with approximately the same rise and span dimensions and under relatively shallow soil cover, we...

S. M. Sargand G. A. Hazen

1990-01-01

3

Singing Corrugated Pipes  

ERIC Educational Resources Information Center

Presents theoretical and experimental observations made with a musical toy called Hummer consisting of a corrugated flexible plastic tube about three-feet long and one-inch diam open at both ends. Included are descriptions of three new instruments: the Water Pipe, the Gas-Pipe Corrugahorn Bugle, and the Gas-Pipe Blues Corrugahorn. (CC)

Crawford, Frank S.

1974-01-01

4

78 FR 5715 - Construction and Maintenance-Culvert Pipe Selection  

Federal Register 2010, 2011, 2012, 2013

...Autonomy for Culvert Pipe Selection,'' requires the Secretary...culvert and storm sewer type selection to either: (a) Include...would have to fit into the natural and constructed environment...to State DOTs regarding the selection of culvert and storm...

2013-01-28

5

Allowable Cover on Corrugated Steel Pipe.  

National Technical Information Service (NTIS)

The objective of the research project was to develop tables of allowable heights of cover for various sizes of prefabricated corrugated steel pipe, pipe arches and field assembled corrugated steel structural plate pipe and pipe arches. Ring compression th...

K. M. Fenwick

1969-01-01

6

Symposium on Durability of Culverts and Storm Drains.  

National Technical Information Service (NTIS)

The 18 papers in this report deal with the following areas: culvert durability: where are we; durability of polymer-coated corrugated steel pipe; durability of drainage structures; overview of polymer coatings for corrugated steel pipe in New York; durabi...

G. W. Ring C. M. Hirsch K. M. Jacobs R. M. Pyskadlo W. W. Renfrew

1984-01-01

7

Corrugated pipe adhesive applicator apparatus  

DOEpatents

Apparatus for coating selected portions of the troughs of a corrugated pipe with an adhesive includes a support disposed within the pipe with a reservoir containing the adhesive disposed on the support. A pump, including a spout, is utilized for supplying the adhesive from the reservoir to a trough of the pipe. A rotatable applicator is supported on the support and contacts the trough of the pipe. The applicator itself is sized so as to fit within the trough, and contacts the adhesive in the trough and spreads the adhesive in the trough upon rotation. A trough shield, supported by the support and disposed in the path of rotation of the applicator, is utilized to prevent the applicator from contacting selected portions of the trough. A locator head is also disposed on the support and provides a way for aligning the spout, the applicator, and the trough shield with the trough. 4 figs.

Shirey, R.A.

1983-06-14

8

Corrugated pipe adhesive applicator apparatus  

DOEpatents

Apparatus for coating selected portions of the troughs of a corrugated pipe within an adhesive includes a support disposed within the pipe with a reservoir containing the adhesive disposed on the support. A pump, including a spout, is utilized for supplying the adhesive from the reservoir to a trough of the pipe. A rotatable applicator is supported on the support and contacts the trough of the pipe. The applicator itself is sized so as to fit within the trough, and contacts the adhesive in the trough and spreads the adhesive in the trough upon rotation. A trough shield, supported by the support and disposed in the path of rotation of the applicator, is utilized to prevent the applicator from contacting selected portions of the trough. A locator head is also disposed on the support and provides a way for aligning the spout, the applicator, and the trough shield with the trough.

Shirey, Ray A. (North Grafton, MA)

1983-06-14

9

Corrugated Pipe as a Beam Dechirper  

SciTech Connect

We have studied the use of a metallic pipe with small corrugations for the purpose of passively dechirping, through its wakefield, a short, intense electron bunch. The corrugated pipe is attractive for this purpose because its wake: (i) has near maximal possible amplitude for a given aperture and (ii) has a relatively large oscillation wave length, even when the aperture is small. We showed how the corrugated structure can satisfy dechirping requirements encountered in the NGLS project at LBNL. We found that a linear chirp of -40 MeV/mm can be induced by an NGLS-like beam, by having it pass through a corrugated, metallic pipe of radius 3 mm, length 8.2 m, and corrugation parameters full depth 450 {mu}m and period 1000 {mu}m. This structure is about 15 times as effective in the role of dechirper as an S-band accelerator structure used passively.

Bane, K.L.F.; Stupakov, G.; /SLAC

2012-04-20

10

Hydraulic Resistance of Small-Diameter Helically Corrugated Metal Pipe.  

National Technical Information Service (NTIS)

The hydraulic resistance of helical CMP is strongly dependent on helix angle the angle of the corrugations relative to the longitudinal axis of the pipe. Smaller-diameter pipes have smaller helix angles. Helical corrugations with a significant downstream ...

B. M. McEnroe T. Malone

2008-01-01

11

Impedance issue of corrugated beam pipe from CDF  

SciTech Connect

The CDF collaboration proposed to install a new corrugated beam pipe at the Tevatron interaction area in order to better monitor the interaction vertex. This note discuss the impedance implication of such a pipe.

Ng, King-Yuen

1993-06-01

12

Predicting Performance of Pipe Culverts Buried in Soil.  

National Technical Information Service (NTIS)

An analytical tool based on the finite element method has been developed to analyze buried culvert problems in a realistic fashion. Segments of a curved bar with three degrees of freedom (normal, tangential and rotational) at each end have been used to si...

G. A. Leonards M. B. Roy

1976-01-01

13

Polymer Coatings for Corrugated Steel Pipe.  

National Technical Information Service (NTIS)

Polymer-coated culverts were first installed in New York State in late 1977. Two different products were used -- 'Nexon', manufactured by the United States Steel Corporation, and 'Beth-Cu-Loy PC', produced by the Bethlehem Steel Corporation. Shortly after...

R. M. Pyskadlo

1979-01-01

14

Performance of Corrugated Pipe Manufactured with Recycled Polyethylene Content.  

National Technical Information Service (NTIS)

The corrugated drainage pipe market in the United States consumes in excess of a billion Pounds of virgin High-Density Polyethylene (HDPE) annually. At the same time, millions of pounds of recyclable HDPE are generated each year. Industry-funded research ...

D. Cuttino R. W. Thomas

2011-01-01

15

Responses of buried corrugated metal pipes to earthquakes  

Microsoft Academic Search

This study describes the results of field investigations and analyses carried out on 61 corrugated metal pipes (CMP) that were shaken by the 1994 Northridge earthquake. These CMPs, which include 29 small-diameter (below 107 cm) CMPs and 32 large-diameter (above 107 cm) CMPs, are located within a 10 km² area encompassing the Van Normal Complex in the Northern San Fernando

C. A. Davis; J. P. Bardet

2000-01-01

16

Wall shape optimization for a thermosyphon loop featuring corrugated pipes  

NASA Astrophysics Data System (ADS)

In the present paper we address the problem of optimal wall-shape design of a single phase laminar thermosyphon loop. The model takes the buoyancy forces into account via the Boussinesq approximation. We focus our study on showing the effects of wall shape on the flow and on the temperature inside the thermosyphon. To this extend we determine the dependency of the flow rate and the increase in temperature, on the geometrical characteristics of the loop. The geometry considered is a set of axially symmetric corrugated pipes described by a set of parameters; namely the pipe inner radius, the period of the corrugation, the amplitude of the corrugation, and the ratio of expansion and contraction regions of a period of the pipe. The governing equations are solved using the Finite Element Method, in combination with an adaptive mesh refinement technique in order to capture the effects of wall shape. We characterize the effects of the amplitude and of the ratio of expansion and contraction. In particular we show that for a given fixed amplitude it is possible to find an optimal ratio of expansion and contraction that minimizes the temperature inside the thermosyphon. The results show that by adequately choosing the design parameters, the performance of the thermosyphon loop can be improved.

Rosen Esquivel, Patricio I.; ten Thije Boonkkamp, Jan H. M.; Dam, Jacques A. M.; Mattheij, Robert M. M.

2012-06-01

17

Terahertz Radiation from a Pipe with Small Corrugations  

SciTech Connect

We have studied through analytical and numerical methods the use of a relativistic electron bunch to drive a metallic beam pipe with small corrugations for the purpose of generating terahertz radiation. For the case of a pipe with dimensions that do not change along its length, we have shown that - with reasonable parameters - one can generate a narrow-band radiation pulse with frequency {approx}1 THz, and total energy of a few milli-Joules. The pulse length tends to be on the order of tens of picoseconds. We have also shown that, if the pipe radius is tapered along its length, the generated pulse will end up with a frequency chirp; if the pulse is then made to pass through a compressor, its final length can be reduced to a few picoseconds and its peak power increased to 1 GW. We have also shown that wall losses tend to be significant and need to be included in the structure design.

Bane, K.L.F.; Stupakov, G.; /SLAC

2012-01-26

18

EXPERIMENTAL STUDY OF THE FLOW-EXCITED ACOUSTICAL LOCK-IN IN A CORRUGATED PIPE  

Microsoft Academic Search

Preliminary experiments to study the aero-acoustic interaction in a corrugated pipe subjected to axial flow are reported. A number of pipes of different diameters, lengths and corrugation pitches and shapes are tested. Results are presented in the light of previous work and the aero- acoustic instability Strouhal numbers are evaluated. We notice that not a single value St is applicable

Vincent Debut; José Antunes; Miguel Moreira

19

Swimming Performance of the Threatened Leopard Darter in Relation to Road Culverts  

Microsoft Academic Search

We investigated the relationship between swinming performance of the leopard darter Percinn pantherina evaluated in the laboratory and current velocities measured at the ends of corrugated-pipe and open-box culverts through road crossings. We tested leopard darters at each of six current velocities ranging from 0 to 60 cmls and measured burst frequency and distance. We uscd analysis of variance (ANOVA)

Conrad S. Toepfer; William L. Fisher; Jason A. Haubelt

1999-01-01

20

Determination of the limiting stress-strain state of helically corrugated pipes  

Microsoft Academic Search

An approximate procedure for calculating the limiting stress-strain state (SSS) of helically corrugated pipes that operate under an axial force is developed. The calculation reduces to determination of the elastoplastic SSS of a shell of revolution with a circular corrugation, which is under axial and torsional loads. The problem is solved using the geometrically nonlinear theory of shells in a

Yu. N. Shevchenko; V. A. Merzlyakov; A. Z. Galishin; S. V. Novikov; P. S. Yukhimets

1993-01-01

21

Surface impedance formalism for a metallic beam pipe with small corrugations  

NASA Astrophysics Data System (ADS)

A metallic pipe with wall corrugations is of special interest in light of recent proposals to use such a pipe for the generation of terahertz radiation and for energy dechirping of electron bunches in free electron lasers. In this paper we calculate the surface impedance of a corrugated metal wall and show that it can be reduced to that of a thin layer with dielectric constant ? and magnetic permeability ?. We develop a technique for the calculation of these constants, given the geometrical parameters of the corrugations. We then calculate, for the specific case of a round metallic pipe with small corrugations, the frequency and strength of the resonant mode excited by a relativistic beam. Our analytical results are compared with numerical simulations, and are shown to agree well. They are also shown to be more accurate when compared to the earlier used analytical model.

Stupakov, G.; Bane, K. L. F.

2012-12-01

22

Surface Impedance Formalism for a Metallic Beam Pipe with Small Corrugations  

SciTech Connect

A metallic pipe with wall corrugations is of special interest in light of recent proposals to use such a pipe for the generation of terahertz radiation and for energy dechirping of electron bunches in free electron lasers. In this paper we calculate the surface impedance of a corrugated metal wall and show that it can be reduced to that of a thin layer with dielectric constant {epsilon} and magnetic permeability {mu}. We develop a technique for the calculation of these constants, given the geometrical parameters of the corrugations. We then calculate, for the specific case of a round metallic pipe with small corrugations, the frequency and strength of the resonant mode excited by a relativistic beam. Our analytical results are compared with numerical simulations, and are shown to agree well.

Stupakov, G.; Bane, K.L.F.; /SLAC

2012-08-30

23

Friction Factors for Hydraulic Design of Corrugated Metal Pipe.  

National Technical Information Service (NTIS)

This paper is based on the results of a research project initiated in 1958 and sponsored jointly by the Bureau of Public Roads and the Office, Chief of Engineers, for the purpose of determining resistance coefficients of structural plate corrugated metal ...

J. L. Grace

1965-01-01

24

Optimization of a technology for producing electric-welded spiral-seam pipes with helical corrugations  

Microsoft Academic Search

The Il'ich Zhdanov Metallurgical Plant collaborated with the O. E. Paton Institute to develop a technology for producing electric-welded spiral-seam pipes measuring 630 X 8 mm. The pipes were made of steel VSt3sp5 with helical corrugations. The have reduced lengthwise stiffness and compensate for axial strains due to temperature changes, internal pressure, and other factors. Existing equipment was modernized and

V. V. Ermakov; O. G. Prokhoda; E. N. Shebanits; V. M. Drozdenko; A. O. Los

1988-01-01

25

Simulation and analysis on ultrasonic testing for the cement grouting defects of the corrugated pipe  

NASA Astrophysics Data System (ADS)

The defects exist in the cement grouting process of prestressed corrugated pipe may directly impair the bridge safety. In this paper, sound fields propagation in concrete structures with corrugated pipes and the influence of various different defects are simulated and analyzed using finite element method. The simulation results demonstrate a much complex propagation characteristic due to multiple reflection, refraction and scattering, where the scattering signals caused by metal are very strong, while the signals scattered by an air bubble are weaker. The influence of defect both in time and frequency domain are found through deconvolution treatment. In the time domain, the deconvolution signals correspond to larger defect display a larger head wave amplitude and shorter arrive time than those of smaller defects; in the frequency domain, larger defect also shows a stronger amplitude, lower center frequency and lower cutoff frequency.

Qingbang, Han; Ling, Chen; Changping, Zhu

2014-02-01

26

1. View east at west facade of culvert outlet headwall, ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

1. View east at west facade of culvert outlet headwall, above which part of the canal bank has been removed. Foreground to background: streambed and coffer dam (mound in center) that was used in dewatering the culvert; intake pipes (extreme left and right) for dewatering pumps; deteriorated culvert outlet headwall with upper portion of wall fallen away; horizontal masonry cutoff wall extending above the culvert outlet partially up the canal bank (cutoff wall was exposed by removal of part of canal bank); towpath at top of canal bank. - Delaware & Raritan Canal, Six Mile Run Culvert, .2 mile South of Blackwells Mills Road, East Millstone, Somerset County, NJ

27

7. VIEW OF A DOUBLE CULVERT IN RAILROAD GRADE, LOOKING ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

7. VIEW OF A DOUBLE CULVERT IN RAILROAD GRADE, LOOKING WEST. THIS CULVERT HAS BEEN IN PLACE SINCE 1933, WHEN IT WAS MARKED ON MONTANA DEPARTMENT OF HIGHWAYS AS-BUILT PLANS. IT LOOKS LIKE THE PIPE ON THE RIGHT (NORTH) IS NOT ORIGINAL. - Great Northern Railroad Bed, From Big Sandy to Verona, Fort Benton, Chouteau County, MT

28

Field Performance Report on Corrugated Polyethylene Pipe on KY 17, Kenton County.  

National Technical Information Service (NTIS)

This report documents the installation and performance of currugated smooth lined polyethylene pipe installed during construction of KY17 in Kenton County. The majority of the pipe installed was N-12 pipe manufactured by Advanced Drainage Systems Inc., an...

L. J. Fleckenstein D. L. Allen

1993-01-01

29

Experimental Demonstration of Energy-Chirp Control in Relativistic Electron Bunches Using a Corrugated Pipe  

NASA Astrophysics Data System (ADS)

The first experimental study is presented of a corrugated wall device that uses wakefields to remove a linear energy correlation in a relativistic electron beam (a "dechirper"). Time-resolved measurements of both longitudinal and transverse wakefields of the device are presented and compared with simulations. This study demonstrates the feasibility to employ a dechirper for precise control of the beam phase space in the next generation of free-electron-lasers.

Emma, P.; Venturini, M.; Bane, K. L. F.; Stupakov, G.; Kang, H.-S.; Chae, M. S.; Hong, J.; Min, C.-K.; Yang, H.; Ha, T.; Lee, W. W.; Park, C. D.; Park, S. J.; Ko, I. S.

2014-01-01

30

Experimental demonstration of energy-chirp control in relativistic electron bunches using a corrugated pipe.  

PubMed

The first experimental study is presented of a corrugated wall device that uses wakefields to remove a linear energy correlation in a relativistic electron beam (a "dechirper"). Time-resolved measurements of both longitudinal and transverse wakefields of the device are presented and compared with simulations. This study demonstrates the feasibility to employ a dechirper for precise control of the beam phase space in the next generation of free-electron-lasers. PMID:24484143

Emma, P; Venturini, M; Bane, K L F; Stupakov, G; Kang, H-S; Chae, M S; Hong, J; Min, C-K; Yang, H; Ha, T; Lee, W W; Park, C D; Park, S J; Ko, I S

2014-01-24

31

Load Distribution on Box Culverts.  

National Technical Information Service (NTIS)

The report contains the results of field investigation of a functional, twin-cell, cast-in-place reinforced concrete box culvert in Sarpy County, Nebraska. Measurements were taken of soil pressures, concrete and steel strains, culvert deflection, and soil...

J. V. Benak, M. K. Tadros

1990-01-01

32

Singing Corrugated Pipes.  

ERIC Educational Resources Information Center

This article describes different techniques used to measure air flow velocity. The two methods used were Crawford's Wastebasket and a video camera. The results were analyzed and compared to the air flow velocity predicted by Bernoulli's principle. (ZWH)

Cadwell, Louis H.

1994-01-01

33

Application of a multistate model to estimate culvert effects on movement of small fishes  

USGS Publications Warehouse

While it is widely acknowledged that culverted road-stream crossings may impede fish passage, effects of culverts on movement of nongame and small-bodied fishes have not been extensively studied and studies generally have not accounted for spatial variation in capture probabilities. We estimated probabilities for upstream and downstream movement of small (30-120 mm standard length) benthic and water column fishes across stream reaches with and without culverts at four road-stream crossings over a 4-6-week period. Movement and reach-specific capture probabilities were estimated using multistate capture-recapture models. Although none of the culverts were complete barriers to passage, only a bottomless-box culvert appeared to permit unrestricted upstream and downstream movements by benthic fishes based on model estimates of movement probabilities. At two box culverts that were perched above the water surface at base flow, observed movements were limited to water column fishes and to intervals when runoff from storm events raised water levels above the perched level. Only a single fish was observed to move through a partially embedded pipe culvert. Estimates for probabilities of movement over distances equal to at least the length of one culvert were low (e.g., generally ???0.03, estimated for 1-2-week intervals) and had wide 95% confidence intervals as a consequence of few observed movements to nonadjacent reaches. Estimates of capture probabilities varied among reaches by a factor of 2 to over 10, illustrating the importance of accounting for spatially variable capture rates when estimating movement probabilities with capture-recapture data. Longer-term studies are needed to evaluate temporal variability in stream fish passage at culverts (e.g., in relation to streamflow variability) and to thereby better quantify the degree of population fragmentation caused by road-stream crossings with culverts. ?? American Fisheries Society 2009.

Norman, J. R.; Hagler, M. M.; Freeman, M. C.; Freeman, B. J.

2009-01-01

34

3. AERIAL VIEW OF SAW MILL RIVER CULVERT. NEPPERHAN AVENUE ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

3. AERIAL VIEW OF SAW MILL RIVER CULVERT. NEPPERHAN AVENUE IS AT LEFT, SLIGHTLY FILLED SAW MILL RIVER CULVERT IS ON RIGHT. - Old Croton Aqueduct, Saw Mill River Culvert, Spanning Nepperhan Avenue, Yonkers, Westchester County, NY

35

ECOLOGICAL CRITERIA FOR PRIORITIZATION OF CULVERT REPLACEMENT  

EPA Science Inventory

Culvert passage issues are gaining national and international focus, because they are implicated in the decline of particular species and in the more general loss of biodiversity in freshwater ecosystems. In the Pacific Northwest, inadequate fish passage at culverts is recognized...

36

Computation of peak discharge at culverts  

USGS Publications Warehouse

Methods for computing peak flood flow through culverts on the basis of a field survey of highwater marks and culvert geometry are presented. These methods are derived from investigations of culvert flow as reported in the literature and on extensive laboratory studies of culvert flow. For convenience in computation, culvert flow has been classified into six types, according to the location of the control section and the relative heights of the head-water and tail-water levels. The type of flow which occurred at any site can be determined from the field data and the criteria given in this report. A discharge equation has been developed for each flow type by combining the energy and continuity equations for the distance between an approach section upstream from the culvert and a terminal section within the culvert barrel. The discharge coefficient applicable to each flow type is listed for the more common entrance geometries. Procedures for computing peak discharge through culverts are outlined in detail for each of the six flow types.

Carter, Rolland William

1957-01-01

37

Midwest Guardrail System for Long-Span Culvert Applications  

Microsoft Academic Search

Long-span guardrail systems have been recognized as an effective means of shielding low-fill culverts. These designs are popular because, in comparison with other systems that attach posts to the top of the culvert, they are able to shield the culvert safely while creating little additional construction effort and limiting the damage to the culvert and the need for repair. However,

Robert Wayne Bielenberg; Ronald K. Faller; Dean L. Sicking; John R. Rohde; John D. Reid

2007-01-01

38

CANDE-1980: Box culverts and soil models  

NASA Astrophysics Data System (ADS)

The CANDE computer program, introduced in 1976 for the structural design and analysis of buried culverts, is extended and enhanced in this work effort to include options for automated finite element analysis of precast, reinforced concrete box culverts, and new nonlinear soil models. User input instructions for the new options, now operative in the CANDE-1980 program, are provided in the appendix of this report along with example input/output data.

Katona, M. G.; Vittes, P. D.; Lee, C. H.; Ho, H. T.

1981-05-01

39

Field Tests of Plastic Pipe for Airport Drainage Systems.  

National Technical Information Service (NTIS)

Airport designers are beginning to select plastic pipe as an alternative in the design of underdrains, storm sewers, culverts, and similar drainage elements at airports because plastic pipe is economical and easy to transport and install. This report prov...

W. J. Horn

1979-01-01

40

3. View southwest at dewatered culvert outlet headwall, with part ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

3. View southwest at dewatered culvert outlet headwall, with part of canal bank removed in back (left) of headwall. - Delaware & Raritan Canal, Ten Mile Run Culvert, 1.5 miles South of Blackwells Road, East Millstone, Somerset County, NJ

41

Frost Heave Patterns and Optimal Design of Insulated Culverts.  

National Technical Information Service (NTIS)

When a culvert is placed under a road, the presence of air at freezing temperatures in the culvert may induce differential frost conditions in pavements. Also, a differential frost heave pattern can appear when the culvert is placed in a frost-susceptible...

C. Duquennoi R. L. Sterling

1991-01-01

42

4. View southeast at culvert outlet with part of the ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

4. View southeast at culvert outlet with part of the canal bank removed. Right to left: dewatered streambed and coffer dam; tops of culvert barrels and curved wingwalls exposed; horizontal masonry cutoff wall partially up the canal bank. - Delaware & Raritan Canal, Six Mile Run Culvert, .2 mile South of Blackwells Mills Road, East Millstone, Somerset County, NJ

43

Corrugated waveguide with helically continuous corrugations  

Microsoft Academic Search

The cylindrical hybrid mode propagation and radiation characteristics have been theoretically analyzed, and corresponding experimental investigations have been carried out for a corrugated waveguide with helical anisotropy. Under the influence of helical corrugation the plane of polarization of the hybrid mode is found to rotate slowly as it moves along the guide. The frequency dependence of the plane of polarization

SUBIR GHOSH; G. P. SRIVASTAVA

1979-01-01

44

Curved Cap Corrugated Sheet.  

National Technical Information Service (NTIS)

The invention is a structure for a strong, lightweight corrugated sheet. The sheet is planar or curved and includes a plurality of corrugation segments, each segment being comprised of a generally U-shaped corrugation with a part-cylindrical crown and cap...

R. C. Davis T. T. Bales D. M. K. Royster L. R. Jackson

1983-01-01

45

Corrugated micromachined membrane structures  

Microsoft Academic Search

Thin film copper membranes on silicon substrates were constructed using microelectronic fabrication techniques. Membranes possessed radial surface corrugation patterns. Membrane sizes ranged from 3.25 mm to 4 mm in diameter. A corrugation height of 10 ?m was chosen to maximize membrane flexibility. Two corrugation pitches were used; 200 ?m and 120 ?m. Double-sided lithography was used to ensure proper alignment

Dwayne D. Chrusch; C. Shafai

2002-01-01

46

Birefringent corrugated waveguide  

DOEpatents

A corrugated waveguide having a circular bore and noncircularly symmetric corrugations, and preferably elliptical corrugations, provides birefringence for rotation of polarization in the HE.sub.11 mode. The corrugated waveguide may be fabricated by cutting circular grooves on a lathe in a cylindrical tube or rod of aluminum of a diameter suitable for the bore of the waveguide, and then cutting an approximation to ellipses for the corrugations using a cutting radius R.sub.0 from the bore axis that is greater than the bore radius, and then making two circular cuts using a radius R.sub.1 less than R.sub.0 at centers +b and -b from the axis of the waveguide bore. Alternatively, stock for the mandrel may be formed with an elliptical transverse cross section, and then only the circular grooves need be cut on a lathe, leaving elliptical corrugations between the grooves. In either case, the mandrel is first electroplated and then dissolved leaving a corrugated waveguide with noncircularly symmetric corrugations. A transition waveguide is used that gradually varies from circular to elliptical corrugations to couple a circularly corrugated waveguide to an elliptically corrugated waveguide.

Moeller, Charles P. (Del Mar, CA)

1990-01-01

47

Corrugated Metallic Cable Sheath  

Microsoft Academic Search

The helically corrugated, impervious, steel sheath is formed around the cable core, welded and corrugated in a continuous operation. This manufacturing method eliminates the thermal problems of the extrusion process, the length restrictions of the sinking or draw-down system, and also increases the pliability and the radial strength of the sheath. The sheath is an impervious barrier to gases and

K. Andresen; F. Dias; N. D. Kenney

1958-01-01

48

Midwest Guardrail System for Long-Span Culvert Applications.  

National Technical Information Service (NTIS)

Long-span guardrail systems have been recognized as an effective means of shielding low-fill culverts. These designs are popular due to their ability to safely shield the culvert while creating little additional construction effort and limiting the damage...

D. L. Sicking E. M. Allison J. C. Holloway J. D. Reid J. R. Rohde K. A. Polivka R. K. Faller R. W. Bielenberg

2007-01-01

49

1. View southeast at northwest facade of dewatered culvert outlet ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

1. View southeast at northwest facade of dewatered culvert outlet headwall, above which part of the canal bank has been removed. Buttresses and upper portion of headwall (above arches) are nineteenth-century additions to the lower, original headwall. - Delaware & Raritan Canal, Ten Mile Run Culvert, 1.5 miles South of Blackwells Road, East Millstone, Somerset County, NJ

50

Fish Movement Ecology in High Gradient Headwater Streams: Its Relevance to Fish Passage Restoration through Stream Culvert Barriers  

USGS Publications Warehouse

Executive Summary Restoration of fish passage through culvert barriers has emerged as a major issue in the Pacific Northwest and nationwide. The problem has many dimensions, including the huge number of potential barriers, uncertainty about which structures are actually barriers, the benefits and risks involved with restoration, and the financial costs and timelines. This report attempts to address what we call 'thinking outside of the pipe' in terms of fish passage information needs. This means understanding the value of each potential passage restoration project in the context of other possible projects, and to view individual restoration projects within a larger landscape of habitats and population processes. In this report we provide a brief review of some essential characteristics of animal movement and examples from a focal group of fishes in Washington State: salmon, trout, and char. While several other fishes and many other species use streams where culvert passage barriers may occur, it is the salmonids that are by far the most widespread and in most cases extending furthest into the headwaters of stream networks in Washington. We begin this report by outlining some basic characteristics of animal movement and then apply that foundation to the case of salmonid fishes. Next we consider the consequences of disrupting fish movement with human-constructed barriers, such as culverts. Finally, this body of evidence is summarized and we propose a short list of what we view as high priority information needs to support more effective restoration of fish passage through culverts.

Hoffman, Robert L.; Dunham, Jason

2007-01-01

51

7. View north at back (canal side) of culvert inlet, ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

7. View north at back (canal side) of culvert inlet, with canal bank completely removed. Background to foreground: back of inlet headwall with tops of high inlet barrels exposed; vertical transition wall between high inlet barrels and low, interior, inlet barrels; tops of low interior barrels; vertical heartening planks and low cutoff wall at site of former canal edge of canal bank; dewatered canal bed and plank sheathing on top of culvert barrels beneath canal bed. - Delaware & Raritan Canal, Ten Mile Run Culvert, 1.5 miles South of Blackwells Road, East Millstone, Somerset County, NJ

52

Contextual view showing drainage culvert in foreground boarding east side ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Contextual view showing drainage culvert in foreground boarding east side of knoll with eucalyptus windbreak. Camera facing 278" southwest. - Goerlitz House, 9893 Highland Avenue, Rancho Cucamonga, San Bernardino County, CA

53

8. A COMPLETED CULVERT ON THE POWER CANAL LOCATED ABOUT ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

8. A COMPLETED CULVERT ON THE POWER CANAL LOCATED ABOUT FOUR MILES EAST OF ROOSEVELT Photographer: Walter J. Lubken, March 29, 1905 - Roosevelt Power Canal & Diversion Dam, Parallels Salt River, Roosevelt, Gila County, AZ

54

8. Double arch culvert on Laurel Creek Road looking WSW. ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

8. Double arch culvert on Laurel Creek Road looking WSW. - Great Smoky Mountains National Park Roads & Bridges, Cades Cove Road & Laurel Creek Road, From Townsend Wye to Cades Cove, Gatlinburg, Sevier County, TN

55

9. Double arch culvert on Laurel Creek Road looking ENE. ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

9. Double arch culvert on Laurel Creek Road looking ENE. - Great Smoky Mountains National Park Roads & Bridges, Cades Cove Road & Laurel Creek Road, From Townsend Wye to Cades Cove, Gatlinburg, Sevier County, TN

56

7. EAST PORTAL OF CONCRETE LINED CULVERT LOCATED 30 YARDS ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

7. EAST PORTAL OF CONCRETE LINED CULVERT LOCATED 30 YARDS WEST OF HAPPY ISLES BRIDGE. NOTE ROCK & CONCRETE FLOOR. - Happy Isles Bridge, Spanning Merced River on Service road, Yosemite Village, Mariposa County, CA

57

6. View southwest, culvert inlet with canal bank completely removed. ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

6. View southwest, culvert inlet with canal bank completely removed. Left to right: back of headwall; tops of high inlet barrels; vertical transition wall between high inlet barrels and low, interior, inlet barrels; tops of low interior barrels; vertical heartening planks and low cutoff wall along former edge of canal bank; dewatered canal bed. - Delaware & Raritan Canal, Ten Mile Run Culvert, 1.5 miles South of Blackwells Road, East Millstone, Somerset County, NJ

58

Dealing With Uncertainty When Assessing Fish Passage Through Culvert Road Crossings  

NASA Astrophysics Data System (ADS)

Assessing the passage of aquatic organisms through culvert road crossings has become increasingly common in efforts to restore stream habitat. Several federal and state agencies and local stakeholders have adopted assessment approaches based on literature-derived criteria for culvert impassability. However, criteria differ and are typically specific to larger-bodied fishes. In an analysis to prioritize culverts for remediation to benefit imperiled, small-bodied fishes in the Upper Coosa River system in the southeastern United States, we assessed the sensitivity of prioritization to the use of differing but plausible criteria for culvert impassability. Using measurements at 256 road crossings, we assessed culvert impassability using four alternative criteria sets represented in Bayesian belief networks. Two criteria sets scored culverts as either passable or impassable based on alternative thresholds of culvert characteristics (outlet elevation, baseflow water velocity). Two additional criteria sets incorporated uncertainty concerning ability of small-bodied fishes to pass through culverts and estimated a probability of culvert impassability. To prioritize culverts for remediation, we combined estimated culvert impassability with culvert position in the stream network relative to other barriers to compute prospective gain in connected stream habitat for the target fish species. Although four culverts ranked highly for remediation regardless of which criteria were used to assess impassability, other culverts differed widely in priority depending on criteria. Our results emphasize the value of explicitly incorporating uncertainty into criteria underlying remediation decisions. Comparing outcomes among alternative, plausible criteria may also help to identify research most needed to narrow management uncertainty.

Anderson, Gregory B.; Freeman, Mary C.; Freeman, Byron J.; Straight, Carrie A.; Hagler, Megan M.; Peterson, James T.

2012-09-01

59

Dealing with uncertainty when assessing fish passage through culvert road crossings.  

PubMed

Assessing the passage of aquatic organisms through culvert road crossings has become increasingly common in efforts to restore stream habitat. Several federal and state agencies and local stakeholders have adopted assessment approaches based on literature-derived criteria for culvert impassability. However, criteria differ and are typically specific to larger-bodied fishes. In an analysis to prioritize culverts for remediation to benefit imperiled, small-bodied fishes in the Upper Coosa River system in the southeastern United States, we assessed the sensitivity of prioritization to the use of differing but plausible criteria for culvert impassability. Using measurements at 256 road crossings, we assessed culvert impassability using four alternative criteria sets represented in Bayesian belief networks. Two criteria sets scored culverts as either passable or impassable based on alternative thresholds of culvert characteristics (outlet elevation, baseflow water velocity). Two additional criteria sets incorporated uncertainty concerning ability of small-bodied fishes to pass through culverts and estimated a probability of culvert impassability. To prioritize culverts for remediation, we combined estimated culvert impassability with culvert position in the stream network relative to other barriers to compute prospective gain in connected stream habitat for the target fish species. Although four culverts ranked highly for remediation regardless of which criteria were used to assess impassability, other culverts differed widely in priority depending on criteria. Our results emphasize the value of explicitly incorporating uncertainty into criteria underlying remediation decisions. Comparing outcomes among alternative, plausible criteria may also help to identify research most needed to narrow management uncertainty. PMID:22744156

Anderson, Gregory B; Freeman, Mary C; Freeman, Byron J; Straight, Carrie A; Hagler, Megan M; Peterson, James T

2012-09-01

60

Dealing with uncertainty when assessing fish passage through culvert road crossings  

USGS Publications Warehouse

Assessing the passage of aquatic organisms through culvert road crossings has become increasingly common in efforts to restore stream habitat. Several federal and state agencies and local stakeholders have adopted assessment approaches based on literature-derived criteria for culvert impassability. However, criteria differ and are typically specific to larger-bodied fishes. In an analysis to prioritize culverts for remediation to benefit imperiled, small-bodied fishes in the Upper Coosa River system in the southeastern United States, we assessed the sensitivity of prioritization to the use of differing but plausible criteria for culvert impassability. Using measurements at 256 road crossings, we assessed culvert impassability using four alternative criteria sets represented in Bayesian belief networks. Two criteria sets scored culverts as either passable or impassable based on alternative thresholds of culvert characteristics (outlet elevation, baseflow water velocity). Two additional criteria sets incorporated uncertainty concerning ability of small-bodied fishes to pass through culverts and estimated a probability of culvert impassability. To prioritize culverts for remediation, we combined estimated culvert impassability with culvert position in the stream network relative to other barriers to compute prospective gain in connected stream habitat for the target fish species. Although four culverts ranked highly for remediation regardless of which criteria were used to assess impassability, other culverts differed widely in priority depending on criteria. Our results emphasize the value of explicitly incorporating uncertainty into criteria underlying remediation decisions. Comparing outcomes among alternative, plausible criteria may also help to identify research most needed to narrow management uncertainty.

Anderson, Gregory B.; Freeman, Mary C.; Freeman, Byron J.; Straight, Carrie A.; Hagler, Megan M.; Peterson, James T.

2012-01-01

61

Towards effective culvert design: monitoring seasonal use and behavior by Mediterranean mesocarnivores.  

PubMed

Drainage culverts are known to be used by a diverse number of species. To date, most studies looking at culvert usage have been restricted to the dry season. This seasonal bias has limited our understanding of how different species respond to culverts and, consequently, our ability to find effective ways to promote the use of culverts as aids to species movement. The main goal of this study was to examine the role of highway culverts for mesocarnivores throughout the year. We addressed (1) the seasonality of culvert use, (2) the relative importance of culvert structure, highway features, and surrounding landscape on culvert use, (3) the influence of the water depth and cover on culvert use, and (4) the effect of culvert structure on individual behavior. Fifteen culverts were monitored along 2 highways in southern Portugal using video-surveillance cameras and marble dust for 10 consecutive days per season. We used generalized linear mixed models to determine which factors most affected the culvert use and behavior by mesocarnivores. Our results highlight the effect of seasonality and water on culvert use. Culvert use was positively related with species activity throughout the year. All species (except otters (Lutra lutra)) were less likely to use culverts that contained water more than 3 cm deep or covering more than 70 % of the culvert base. Based on our results, future surveys and culvert retrofit design should address (1) the importance of seasonality in the interpretation of results and (2) the complementarity of culvert-specific features (water, ledges, and naturalization). PMID:23208760

Serronha, Ana Marta; Mateus, Ana Rita Amaro; Eaton, Finn; Santos-Reis, Margarida; Grilo, Clara

2013-08-01

62

Voice of the dragon: the rotating corrugated resonator  

Microsoft Academic Search

A simple, yet unusual, child's toy illustrates some basic features of the physics of resonance, waves and fluid dynamics. The acoustic modes of a corrugated tube open at both ends and rotating in a plane were examined as a function of rotational frequency and found to be similar but not identical to those of a stationary open-ended organ pipe. Measurements

M. P. Silverman; G. M. Cushman

1989-01-01

63

Impact of Economic Risks on Box Culvert Designs--on Application to 22 Virginia Sites.  

National Technical Information Service (NTIS)

The report demonstrates the results of a preliminary effort to incorporate economic risks into culvert design and to relate this economic design to conventional design practice for 22 culvert sites in Virginia. Economic design is defined as the minimum an...

G. K. Young M. R. Childrey

1974-01-01

64

Investigation of Culvert Hydraulics Related to Juvenile Fish Passage. Final Research Report.  

National Technical Information Service (NTIS)

Culverts often create barriers to the upstream migration of juvenile fish. The objective of this study was to determine hydraulic characteristics of culverts with different flow conditions. Methods of predicting flow profiles were developed by both Chiu a...

M. E. Barber R. C. Downs

1996-01-01

65

An Improved Method of Manufacturing Corrugated Boxes: Lateral Corrugator  

SciTech Connect

Paper physicists have known that a corrugated box constructed from outer liner sheets having a predominant fiber orientation aligned with the corrugating flute direction would have higher stiffness and crush resistance (per unit of fiber weight) than the conventional box construction. Such increased performance per unit of fiber weight could result in fiber reduction and energy savings for boxes having equivalent performance specifications. The goal of this project was to develop and demonstrate a commercially viable lateral corrugating process. This included designing and building a pilot lateral corrugator, testing and evaluating pilot machine made boxes, and developing a strategy for commercialization.

Frank C. Murray Ph.D.; , Roman Popil Ph.D.; Michael Shaepe (formerly with IPST, now at Cargill. Inc)

2008-12-18

66

Linear Corrugating - Final Technical Report  

SciTech Connect

Linear Corrugating is a process for the manufacture of corrugated containers in which the flutes of the corrugated medium are oriented in the Machine Direction (MD) of the several layers of paper used. Conversely, in the conventional corrugating process the flutes are oriented at right angles to the MD in the Cross Machine Direction (CD). Paper is stronger in MD than in CD. Therefore, boxes made using the Linear Corrugating process are significantly stronger-in the prime strength criteria, Box Compression Test (BCT) than boxes made conventionally. This means that using Linear Corrugating boxes can be manufactured to BCT equaling conventional boxes but containing 30% less fiber. The corrugated container industry is a large part of the U.S. economy, producing over 40 million tons annually. For such a large industry, the potential savings of Linear Corrugating are enormous. The grant for this project covered three phases in the development of the Linear Corrugating process: (1) Production and evaluation of corrugated boxes on commercial equipment to verify that boxes so manufactured would have enhanced BCT as proposed in the application; (2) Production and evaluation of corrugated boxes made on laboratory equipment using combined board from (1) above but having dual manufactures joints (glue joints). This box manufacturing method (Dual Joint) is proposed to overcome box perimeter limitations of the Linear Corrugating process; (3) Design, Construction, Operation and Evaluation of an engineering prototype machine to form flutes in corrugating medium in the MD of the paper. This operation is the central requirement of the Linear Corrugating process. Items I and II were successfully completed, showing predicted BCT increases from the Linear Corrugated boxes and significant strength improvement in the Dual Joint boxes. The Former was constructed and operated successfully using kraft linerboard as the forming medium. It was found that tensile strength and stretch characteristics of the corrugating medium were not sufficient to allow fluting this paper in the former. Possible causes and corrective actions to overcome this problem are addressed in the body of the report below.

Lloyd Chapman

2000-05-23

67

7. VIEW OF WEAPONS DELIVERY ROAD CULVERT OF LOWER DIAGONAL ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

7. VIEW OF WEAPONS DELIVERY ROAD CULVERT OF LOWER DIAGONAL NO. 1 DRAIN, LOOKING 522 EAST OF NORTH. - Truckee-Carson Irrigation District, Lower Diagonal No. 1 Drain, Bounded by West Gate Road & Weapons Delivery Road, Naval Air Station Fallon, Fallon, Churchill County, NV

68

5. VIEW OF WEST GATE ROAD CULVERT OF LOWER DIAGONAL ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

5. VIEW OF WEST GATE ROAD CULVERT OF LOWER DIAGONAL NO. 1 DRAIN, LOOKING 323' EAST OF NORTH. - Truckee-Carson Irrigation District, Lower Diagonal No. 1 Drain, Bounded by West Gate Road & Weapons Delivery Road, Naval Air Station Fallon, Fallon, Churchill County, NV

69

35. Photo of concrete arch culvert constructed by Puget Sound ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

35. Photo of concrete arch culvert constructed by Puget Sound Construction Company, 1911, for the Northern Pacific Railroad, over flume. Photo by Brian C. Morris, Puget Power, 1989. - Puget Sound Power & Light Company, White River Hydroelectric Project, 600 North River Avenue, Dieringer, Pierce County, WA

70

Flood magnitude and frequency of Main Ditch at the culvert on New Jersey Route 44 and at the Conrail culvert downstream, West Deptford Township, Gloucester County, New Jersey  

USGS Publications Warehouse

The magnitude and frequency of floods at Main Ditch at the culvert on New Jersey Route 44 at milepost 8.3 and at the Conrail culvert 0.21 miles downstream, in West Deptford Township, New Jersey, were determined by using the New Jersey Department of Environmental Protection Special Report 38 method. Flood-magnitude and -frequency estimates, as well as drainage-basin characteristics, are included in this report. The 100-year-flood estimates are 285 cubic feet per second at the culvert on New Jersey Route 44 and 345 cubic feet per second at the Conrail culvert.

Barringer, Thomas

1996-01-01

71

Effect of corrugated characteristics on the liquid nitrogen temperature field of HTS cable  

NASA Astrophysics Data System (ADS)

In the high temperature superconducting (HTS) cable system, liquid nitrogen is usually chosen to be the coolant because of its low saturation temperature and large latent heat of vaporization. Thus, it is very important for superconducting cables that the liquid nitrogen temperature field keeps stable. However, the cryostat is usually made of flexible corrugated pipes and multi-layer insulation materials. The characteristics (e.g. wave pitch and wave depth) of corrugated pipes may have an effect on the heat exchange between cable and liquid nitrogen, even the whole temperature field of liquid nitrogen. In this paper, a two-dimensional model for 30 m long HTS cable has been modified to analyze the effect of corrugated characteristics on the temperature field of liquid nitrogen. The liquid nitrogen temperature difference between the outlet and the inlet of passage gradually increases as the wave pitch of the corrugated tube decreases and the wave depth increases.

Li, Z. M.; Li, Y. X.; Zhao, Y. Q.; Gao, C.; Qiu, M.; Chen, G. F.; Gong, M. Q.; Wu, J. F.

2014-01-01

72

330 GHz helically corrugated waveguide  

Microsoft Academic Search

Corrugated waveguide made with a tap can significantly lower fabrication costs. A 330 GHz, 19 mm i.d., 4.5 m long brass circular waveguide was tapped and tested. Transmission measurements were compared with models that take into account the shape of the corrugation.

Paul P. Woskov; Emilio A. Nanni; Michael A. Shapiro; Sudheer K. Jawla; Jason S. Hummelt; Richard J. Temkin; Alexander B. Barnes

2011-01-01

73

Review on rail corrugation studies  

Microsoft Academic Search

In Japan, rail corrugations had not been so serious formerly, but it began to be prevailing in recent years. In order to prevent the generation of rail corrugation, many studies have been reported in the world since the end of 19th century, but theories on them have not explained the formation mechanism perfectly and no perfect countermeasures have been established

Yoshihiko Sato; Akira Matsumoto; Klaus Knothe

2002-01-01

74

Stacked Corrugated Horn Rings  

NASA Technical Reports Server (NTRS)

This Brief describes a method of machining and assembly when the depth of corrugations far exceeds the width and conventional machining is not practical. The horn is divided into easily machined, individual rings with shoulders to control the depth. In this specific instance, each of the corrugations is identical in profile, and only differs in diameter and outer profile. The horn is segmented into rings that are cut with an interference fit (zero clearance with all machining errors biased toward contact). The interference faces can be cut with a reverse taper to increase the holding strength of the joint. The taper is a compromise between the interference fit and the clearance of the two faces during assembly. Each internal ring is dipped in liquid nitrogen, then nested in the previous, larger ring. The ring is rotated in the nest until the temperature of the two parts equalizes and the pieces lock together. The resulting assay is stable, strong, and has an internal finish that cannot be achieved through other methods.

Sosnowski, John B.

2010-01-01

75

Turtles and culverts, and alternative energy development: an unreported but potentially significant mortality threat to the desert tortoise (Gopherus agassizii)  

USGS Publications Warehouse

Culverts are often used to increase the permeability of roaded landscapes for wildlife, including turtles. Although the benefits of culverts as safe passages for turtles are well documented, under some conditions culverts can entrap them and cause mortality. Here we report a culvert-related mortality in the federally threatened desert tortoise (Gopherus agassizii) at a wind energy facility in California and offer simple recommendations to mitigate the negative effects of culverts for wildlife in general.

Lovich, J. E.; Ennen, J. R.; Madrak, S.; Grover, B.

2011-01-01

76

Culvert Analysis Program Graphical User Interface 1.0--A preprocessing and postprocessing tool for estimating flow through culvert  

USGS Publications Warehouse

The peak discharge of a flood can be estimated from the elevation of high-water marks near the inlet and outlet of a culvert after the flood has occurred. This type of discharge estimate is called an “indirect measurement” because it relies on evidence left behind by the flood, such as high-water marks on trees or buildings. When combined with the cross-sectional geometry of the channel upstream from the culvert and the culvert size, shape, roughness, and orientation, the high-water marks define a water-surface profile that can be used to estimate the peak discharge by using the methods described by Bodhaine (1968). This type of measurement is in contrast to a “direct” measurement of discharge made during the flood where cross-sectional area is measured and a current meter or acoustic equipment is used to measure the water velocity. When a direct discharge measurement cannot be made at a streamgage during high flows because of logistics or safety reasons, an indirect measurement of a peak discharge is useful for defining the high-flow section of the stage-discharge relation (rating curve) at the streamgage, resulting in more accurate computation of high flows. The Culvert Analysis Program (CAP) (Fulford, 1998) is a command-line program written in Fortran for computing peak discharges and culvert rating surfaces or curves. CAP reads input data from a formatted text file and prints results to another formatted text file. Preparing and correctly formatting the input file may be time-consuming and prone to errors. This document describes the CAP graphical user interface (GUI)—a modern, cross-platform, menu-driven application that prepares the CAP input file, executes the program, and helps the user interpret the output

Bradley, D. Nathan

2013-01-01

77

LONG-SPAN GUARDRAIL SYSTEM FOR CULVERT APPLICATIONS  

Microsoft Academic Search

A long-span guardrail for use over low-fill culverts was developed and successfully crash tested. The guardrail system was configured with 30.48 m of nested, 12-gauge W-beam rail and centered around a 7.62-m-long unsupported span. The nested W-beam rail was supported by 16 W152 x 13.4 steel posts and 6 standard CRT posts, each with two 150-mm x 200 x 360

Ronald K Faller; Dean L Sicking; Karla A Polivka; John R Rohde; Bob W Bielenberg

2000-01-01

78

24. CULVERT WITH CONCRETE HEADWALL AND SIDEWALLS CARRYING THE LATERAL ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

24. CULVERT WITH CONCRETE HEADWALL AND SIDEWALLS CARRYING THE LATERAL UNDER 8TH AVENUE. - Highline Canal, Sand Creek Lateral, Beginning at intersection of Peoria Street & Highline Canal in Arapahoe County (City of Aurora), Sand Creek lateral Extends 15 miles Northerly through Araphoe County, City & County of Denver, & Adams County to its end point, approximately 1/4 mile Southest of intersectioin of D Street & Ninth Avenue in Adams County (Rocky Mountain Arsenal, Commerce City Vicinity), Commerce City, Adams County, CO

79

Effect of Wheel Live Load on Shear Behavior of Precast Reinforced Concrete Box Culverts  

Microsoft Academic Search

This study reports on a part of a comprehensive study to evaluate the shear capacity of the precast reinforced concrete box culverts. Six full-scale 2.4 m 8f t span box culverts were tested to failure by subjecting each culvert to the AASHTO HS-20 wheel load. The location of the wheel load was varied from the tip of the haunch as

Ali Abolmaali; Anil K. Garg

2008-01-01

80

49 CFR 1242.15 - Roadway, tunnels and subways, bridges and culverts, ties, rails, other track material, ballast...  

Code of Federal Regulations, 2010 CFR

...Roadway, tunnels and subways, bridges and culverts, ties, rails, other track material, ballast, track laying and...Roadway, tunnels and subways, bridges and culverts, ties, rails, other track material, ballast, track laying...

2010-10-01

81

49 CFR 1242.15 - Roadway, tunnels and subways, bridges and culverts, ties, rails, other track material, ballast...  

Code of Federal Regulations, 2010 CFR

...Roadway, tunnels and subways, bridges and culverts, ties, rails, other track material, ballast, track laying and...Roadway, tunnels and subways, bridges and culverts, ties, rails, other track material, ballast, track laying...

2009-10-01

82

Juvenile Coho Salmon Leaping Ability and Behavior in an Experimental Culvert Test Bed  

Microsoft Academic Search

As part of a research program aimed at identifying the culvert configurations and associated hydraulic conditions that foster the successful upstream movement of juvenile salmon, we investigated the ability of hatchery-raised juvenile coho salmon Oncorhynchus kisutch to leap into an experimental culvert under varying hydraulic conditions. Five outfall drops ranging from 0 to 32 cm were tested to represent differing

Robert P. Mueller; Susan S. Southard; Christopher W. May; Walter H. Pearson; Valerie I. Cullinan

2008-01-01

83

LOCATING DITCH RELIEF CULVERTS TO REDUCE SEDIMENT DELIVERY TO STREAMS - AN INTERACTIVE DESIGN TOOL  

Microsoft Academic Search

A model has been developed which allows a designer to optimize the location of ditch relief culverts to minimize sediment deliveries to streams. The model provides immediate visual feedback allowing the designer to rapidly evaluate and optimize various ditch relief culvert locations. The model's sediment delivery and routing algorithms are based on existing methodologies. Current as well as planned road

Peter Schiess; Finn Krogstad; Florentiu Damian

84

6. VIEW OF A RUSTED, HEAVYGAUGE METAL CULVERT (TY31776) PLACED ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

6. VIEW OF A RUSTED, HEAVY-GAUGE METAL CULVERT (TY-3177-6) PLACED AT A SMALL DRAW WHERE KINGS CANYON ROAD WILL BE INSLOPED AND THE CULVERT WILL BE REMOVED. LOCATED AT MILEPOST 0.05 (ACCORDING TO THE ARCHAEOLOGICAL SITE RECORD FOR TY-3177). FACING SOUTH 76ø WEST (256ø). - Kings Canyon Road, Carson City, Carson City, NV

85

Assessment of Trout Passage through Culverts in a Large Montana Drainage during Summer Low Flow  

Microsoft Academic Search

We used a combination of methods to assess the degree of fish passage restriction from road culverts during summer low flow for westslope cutthroat trout Oncorhynchus clarkii lewisi and brook trout Salvelinus fontinalis across a large drainage basin. The FishXing fish passage model classified 41 of 45 (91%) culverts as barriers to upstream passage for 152-mm westslope cutthroat trout. Population

D. Drake Burford; Thomas E. McMahon; Joel E. Cahoon; Matthew Blank

2009-01-01

86

Investigation of culvert hydraulics related to juvenile fish passage. Final research report  

Microsoft Academic Search

Culverts often create barriers to the upstream migration of juvenile fish. The objective of this study was to determine hydraulic characteristics of culverts with different flow conditions. Methods of predicting flow profiles were developed by both Chiu and Mountjoy. Two equations were compared to experimental results. An area of flow corresponding to a predetermined allowable velocity can be calculated using

M. E. Barber; R. C. Downs

1996-01-01

87

MONITORING CULVERT PASSAGE OF JUVENILE SALMONIDS WITH PIT TAGS AND STATIONARY AND PORTABLE PIT-TAG READERS  

EPA Science Inventory

Federal land management agencies in the PNW face increasing pressure to replace culverts that do not pass all life history stages of anadromous salmon and trout. Prioritization of culverts for replacement is often based on the physical parameters of culverts, and not on how fish...

88

A Simple Experiment to Explore Standing Waves in a Flexible Corrugated Sound Tube  

ERIC Educational Resources Information Center

Sound tubes, pipes, and singing rods are used as musical instruments and as toys to perform amusing experiments. In particular, corrugated tubes present unique characteristics with respect to the sounds they can produce; that is why they have been studied so intensively, both at theoretical and experimental levels. Experimental studies usually…

Amorim, Maria Eva; Sousa, Teresa Delmira; Carvalho, P. Simeao; Sousa, Adriano Sampaioe

2011-01-01

89

Corrugated quantum well infrared photodetectors  

Microsoft Academic Search

We introduce here a novel light coupling scheme for quantum well infrared photodetectors (QWIPs). The new device structure utilizing this coupling scheme, referred to as the corrugated QWIP (C-QWIP), couples normal incident light effectively even for detector size as small as 50×50 ?m 2 and shows little spectrum narrowing effect, indicating that it can be applied to the manufacturing of

C. J. Chen; K. K. Choi; D. C. Tsui

1996-01-01

90

Assessing Juvenile Salmonid Passage Through Culverts: Field Research in Support of Protocol Development  

SciTech Connect

The primary goal of our research this spring/ summer was to refine techniques and examine scenarios under which a standardized protocol could be applied to assess juvenile coho salmon (O. kisutch) passage through road culverts. Field evaluations focused on capture-mark- recapture methods that allowed analysis of fish movement patterns, estimates of culvert passability, and potential identification of cues inducing these movements. At this stage, 0+ age coho salmon fry 30 mm to 65 mm long (fork length) were the species and age class of interest. Ultimately, the protocol will provide rapid, statistically rigorous methods for trained personnel to perform standardized biological assessments of culvert passability to a number of juvenile salmon species. Questions to be addressed by the research include the following: ? Do hydraulic structures such as culverts restrict habitat for juvenile salmonids? ? How do existing culverts and retrofits perform relative to juvenile salmonid passage? ? Do some culvert characteristics and hydraulic conditions provide better passage than others? ? Does the culvert represent a barrier to certain size classes of fish? Recommendations addressed issues of study site selection, initial capture, marking, recapture/observations, and estimating movement.

Williams, Greg D.; Evans, Nathan R.; Pearson, Walter H.; Southard, John A.

2001-10-30

91

Investigation of culvert hydraulics related to juvenile fish passage. Final research report  

SciTech Connect

Culverts often create barriers to the upstream migration of juvenile fish. The objective of this study was to determine hydraulic characteristics of culverts with different flow conditions. Methods of predicting flow profiles were developed by both Chiu and Mountjoy. Two equations were compared to experimental results. An area of flow corresponding to a predetermined allowable velocity can be calculated using Mountjoy equation. This can then be used in the design of culverts as fish passage guidelines. The report contains a summary of background information, experimental methodology, the results of experimental tests, and an analysis of both the Chiu and Mountjoy equations.

Barber, M.E.; Downs, R.C.

1996-01-01

92

Corrugated Membrane Fuel Cell Structures  

SciTech Connect

One of the most challenging aspects of traditional PEM fuel cell stacks is the difficulty achieving the platinum catalyst utilization target of 0.2 gPt/kWe set forth by the DOE. Good catalyst utilization can be achieved with state-of-the-art catalyst coated membranes (CCM) when low catalyst loadings (<0.3 mg/cm2) are used at a low current. However, when low platinum loadings are used, the peak power density is lower than conventional loadings, requiring a larger total active area and a larger bipolar plate. This results in a lower overall stack power density not meeting the DOE target. By corrugating the fuel cell membrane electrode structure, Ion Power?s goal is to realize both the Pt utilization targets as well as the power density targets of the DOE. This will be achieved by demonstrating a fuel cell single cell (50 cm2) with a twofold increase in the membrane active area over the geometric area of the cell by corrugating the MEA structure. The corrugating structure must be able to demonstrate the target properties of < 10 mOhm-cm2 electrical resistance at > 20 psi compressive strength over the active area, in combination with offering at least 80% of power density that can be achieved by using the same MEA in a flat plate structure. Corrugated membrane fuel cell structures also have the potential to meet DOE power density targets by essentially packaging more membrane area into the same fuel cell volume as compared to conventional stack constructions.

Grot, Stephen [President, Ion Power Inc.] President, Ion Power Inc.

2013-09-30

93

Fundamentals of Culvert Design for Passage of Weak-Swimming Fish.  

National Technical Information Service (NTIS)

Properly designed culverts do not produce water velocities that exceed fish swimming abilities. Fish have two different musculature systems for swimming. A white muscle system generates power for short vigorous swimming. A red muscle system furnishes powe...

C. E. Behlke D. L. Kane R. F. McLean M. D. Travis

1991-01-01

94

(Graficos Hidraulicos para el Dideno de Alcantarillas) Hydraulic Charts for the Selection of Highway Culverts.  

National Technical Information Service (NTIS)

The report is a translation into Spanish of the popular and useful publication Hydraulic Charts for the Selection of Highway Culverts, published in 1965 but still considered pertinent today. A current bibliography has been added. Measurements have been gi...

L. A. Herr H. G. Bossy

1974-01-01

95

PVA Fiber Reinforced Shotcrete for Rehabilitation and Preventative Maintenance of Aging Culverts.  

National Technical Information Service (NTIS)

The goal of this project was to investigate the potential for using PVA (polyvinyl alcohol) fiber reinforced mortar for the rehabilitation and preventative maintenance of aging metal highway drainage culverts using a spray-on liner application approach. T...

B. Pillay B. Thattaiparthasarat J. Kang J. S. Davidson U. K. Vaidya

2008-01-01

96

Investigation of Culvert Hydraulics Related to Juvenile Fish Passage. Final Technical Report.  

National Technical Information Service (NTIS)

The objective of this study was to determine hydraulic characteristics of culverts with different flow conditions. Methods of predicting flow profiles were developed by both Chiu and Mountjoy. Two equations were compared to experimental results. The Mount...

M. E. Barber R. C. Downs

1996-01-01

97

Stiffness and Stress Analysis of Discretely Attached Corrugated Shear Webs with Quasi-Sinusoidal Corrugations.  

National Technical Information Service (NTIS)

A theoretical analysis and numerical data are presented for the shear stiffness of curvilinearly corrugated shear webs with discrete attachments to framing members at the ends of the corrugations, and for the maximum transverse extreme-fiber flexural stre...

L. H. Wu C. Libove

1975-01-01

98

Experimental Investigation of Shear Capacity of Precast Reinforced Concrete Box Culverts  

Microsoft Academic Search

This study presents an experimental program to investigate the shear capacity of precast reinforced concrete box culverts. Each culvert was subjected to monotonically increasing load through a 254 mm508 mm 10 in.20 in. load plate in order to simulate the HS20 truckload per AASHTO 2005. Instrumentation included strain gauges, high-resolution laser deflection sensor, and automated data acquisition. Four tests were

Anil K. Garg; Ali Abolmaali; Raul Fernandez

2007-01-01

99

Influence of Corrugation Profile on the Thermalhydraulic Performance of Cross-Corrugated Plates  

Microsoft Academic Search

This article presents a numerical investigation on the thermalhydraulic performance of cross-corrugated plates, commonly employed in plate and compact heat exchangers. Three-dimensional numerical predictions were obtained using a finite volume method and a validated low Reynolds number k-? turbulence model. The influences of Reynolds number, corrugation inclination angle, and especially corrugation profile on flow and heat transfer were studied and

Lei Zhang; Defu Che

2011-01-01

100

A parametric study of cut-off corrugated surface properties  

NASA Technical Reports Server (NTRS)

Corrugated horns involve a junction between the corrugated surface and a conducting groundplane. Proper horn design requires an understanding of the electromagnetic properties of the corrugated surface and this junction. Therefore, an integral equation solution has been used to study the influence of corrugation density and shape on the power loss. Surface current, and the scattering from a groundplane-corrugated surface junction. Both square and vee shape corrugations have been considered over the range of corrugation depths where the surface acts as a cut-off corrugated surface.

Mentzer, C. A.; Peters, L., Jr.

1973-01-01

101

Low-profile corrugated feeder antenna  

Microsoft Academic Search

A very low-profile planar rectangular horn antenna made of a subwavelength aperture surrounded by two grooves on the conducting plate is presented. This structure exhibits good return losses and radiated beam. Its operation is based upon enhanced transmission and beaming through apertures in metallic corrugated plates. Here, the corrugated structure is designed to operate in microwaves and, moreover, a waveguide

M. Beruete; I. Campillo; J. S. Dolado; J. E. Rodriguez-Seco; E. Perea; F. Falcone; M. Sorolla

2005-01-01

102

Helically corrugated circular waveguides as antenna feeders  

Microsoft Academic Search

Rotation of the plane of polarization of the TE(11)-mode is predicted and observed in a helically corrugated circular waveguide. Rotation is suppressed by a longitudinal deformation produced on the corrugation. This modified structure can be used as an antenna feeder with low losses.

F. Jecko; A. Papiernik

1983-01-01

103

Helically corrugated circular waveguides as antenna feeders  

NASA Astrophysics Data System (ADS)

Rotation of the plane of polarization of the TE(11)-mode is predicted and observed in a helically corrugated circular waveguide. Rotation is suppressed by a longitudinal deformation produced on the corrugation. This modified structure can be used as an antenna feeder with low losses.

Jecko, F.; Papiernik, A.

1983-07-01

104

RF Pulse Compression Using Helically Corrugated Waveguides  

Microsoft Academic Search

This paper describes the use of a helically corrugated waveguide as a dispersive medium for microwave pulse compression. The helically corrugated waveguide has a large variation of group velocity with frequency, but in a region where the group velocity remains large. Therefore this compressor does not suffer from reflections associated with cut-off scenarios at frequencies close to its operating regime

P. Macinnes; K. Ronald; G. Burt; A. W. Cross; A. R. Young; A. D. R. Phelps; I. V. Konoplev; W. He; S. V. Samsonov; V. L. Bratman; G. G. Denisov

2006-01-01

105

NONLINEAR FINITE ELEMENT MODELING OF CORRUGATED BOARD  

Microsoft Academic Search

In this research, an investigation on the mechanical behavior of corrugated board has been performed using finite element analysis. Numerical finite element models for corrugated board geometries have been created and executed Both geometric (large deformation) and material nonlinearities were included in the models. The analyses were performed using the commercial nonlinear finite element code ABAQUS executed on Sun SparcStations

A. C. Gilchrist; J. C. Suhling; T. J. Urbanik

106

Truss-Core Corrugation for Compression Loads.  

National Technical Information Service (NTIS)

A corrugated panel structure for supporting compressive loads is described which includes curved cap strips separated by truss-core web segments. The truss-core web segments are formed from first and second flat panels with a corrugated filler therebetwee...

R. C. Davis L. R. Jackson

1987-01-01

107

Characterization of corrugated waveguides by modal analysis  

Microsoft Academic Search

A general formulation for the characterization of corrugated waveguides is presented. The formulation is based on modal expansion in the different smooth-walled waveguides which constitute the corrugated structure and on the use of mode matching at discontinuities. The use of an admittance matrix formulation and a suitable root-finding algorithm leads to a rigorous and efficient technique. Dispersion curves are presented

Jaime Esteban; JesGs M. Rebollar

1991-01-01

108

Estimates for Pu-239 loadings in burial ground culverts based on fast/slow neutron measurements  

SciTech Connect

This report provides guideline estimates for Pu-239 mass loadings in selected burial ground culverts. The relatively high recorded Pu-239 contents of these culverts have been appraised as suspect relative to criticality concerns, because they were assayed only with the solid waste monitor (SWM) per gamma-ray counting. After 1985, subsequent waste was also assayed with the neutron coincidence counter (NCC), and a comparison of the assay methods showed that the NCC generally yielded higher assays than the SWM. These higher NCC readings signaled a need to conduct non-destructive/non-intrusive nuclear interrogations of these culverts, and a technical team conducted scoping measurements to illustrate potential assay methods based on neutron and/or gamma counting. A fast/slow neutron method has been developed to estimate the Pu-239 in the culverts. In addition, loading records include the SWM assays of all Pu-239 cuts of some of the culvert drums and these data are useful in estimating the corresponding NCC drum assays from NCC vs SWM data. Together, these methods yield predictions based on direct measurements and statistical inference.

Winn, W.G.; Hochel, R.C.; Hofstetter, K.J.; Sigg, R.A.

1989-08-15

109

Method for X-ray Radiography of Insulating Covers of Culverts for District Heating Pipes.  

National Technical Information Service (NTIS)

A special procedure using tangential x-ray beam direction, very low kilovoltage and x-ray sensitive IC-paper (Instant copy paper) has been developed for practical field application. The main advantages of using IC-paper instead of transparent film are low...

S. Dahn

1987-01-01

110

Investigation of culvert hydraulics related to juvenile fish passage. Final technical report  

SciTech Connect

The objective of this study was to determine hydraulic characteristics of culverts with different flow conditions. Methods of predicting flow profiles were developed by both Chiu and Mountjoy. Two equations were compared to experimental results. The Mountjoy equation proved to yield better results for velocity profile predictions. An area of flow corresponding to a predetermined allowable velocity can be calculated using the Mountjoy equation. This can then be used in the design of culverts as fish passage guidelines. The technical report contains a detailed description of background information, experimental methodology, the results of experimental tests, and an analysis of both the Chiu and Mountjoy equations.

Barber, M.E.; Downs, R.C.

1996-01-01

111

MICROWAVE DEVICES WITH HELICALLY CORRUGATED WAVEGUIDES  

Microsoft Academic Search

Helical corrugation of the inner surface of an oversized circular waveguide provides very flexible dispersion characteristic\\u000a of an eigenwave. Under certain corrugation parameters, the eigenwave can possess a sufficiently high and almost constant group\\u000a velocity over a wide frequency band in the region of close-to-zero axial wavenumber. This makes it attractive for broadband\\u000a gyro- TWTs and gyro-BWOs with reduced sensitivity

V. L. Bratman; A. W. Cross; G. G. Denisov; A. D. R. Phelps; S. V. Samsonov

112

Predicting the Ultimate Load Carrying Capacity of Long-Span Precast Concrete Arch Culverts.  

National Technical Information Service (NTIS)

In a previous full-scale live load test, partially sponsored by the Ohio Department of Transportation, conducted on a 36-ft precast reinforced concrete culvert the ultimate load carrying capacity could not be established due to the limited hydraulic jack'...

M. Zoghi

2000-01-01

113

Design and Proof Test Requirements for Precast Reinforced Concrete Box Culverts.  

National Technical Information Service (NTIS)

The accuracy of a proposed proof test for single cell box culverts was verified by testing 16 full size specimens. The proof test involved placing a symmetrical arrangement of concentrated loads against the upper and lower slabs. The measured strength was...

H. M. F. Ghanem J. P. Lloyd

1977-01-01

114

Investigation of culvert hydraulics related to juvenile fish passage. Final technical report  

Microsoft Academic Search

The objective of this study was to determine hydraulic characteristics of culverts with different flow conditions. Methods of predicting flow profiles were developed by both Chiu and Mountjoy. Two equations were compared to experimental results. The Mountjoy equation proved to yield better results for velocity profile predictions. An area of flow corresponding to a predetermined allowable velocity can be calculated

M. E. Barber; R. C. Downs

1996-01-01

115

Imaging Buried Culverts Using Ground Penetrating Radar: Comparing 100 MHZ Through 1 GHZ Antennae  

NASA Astrophysics Data System (ADS)

*Aziz, A A aabdulaziz@uh.edu Allied Geophysical Lab, Department of Earth and Atmospheric Sciences, University of Houston, TX, USA Stewart, R R rrstewart@uh.edu Allied Geophysical Lab, Department of Earth and Atmospheric Sciences, University of Houston, TX, USA *Green, S L slgreen@yahoo.com Allied Geophysical Lab, Department of Earth and Atmospheric Sciences, University of Houston, TX, USA A 3D ground penetrating radar (GPR) survey, using three different frequency antennae, was undertaken to image buried steel culverts at the University of Houston's La Marque Geophysical Observatory 30 miles south of Houston, Texas. The four culverts, under study, support a road crossing one of the area's bayous. A 32 m by 4.5 m survey grid was designed on the road above the culverts and data were collected with 100 MHz, 250 MHz, and 1 GHz antennae. We used an orthogonal acquisition geometry for the three surveys. Inline sampling was from 1.0 cm to 10 cm (from 1 GHz to 100 MHz antenna) with inline and crossline spacings ranging from 0.2 m to 0.5 m. We used an initial velocity of 0.1 m/ns (from previous CMP work at the site) for the display purposes. The main objective of the study was to analyze the effect of different frequency antennae on the resultant GPR images. We are also interested in the accuracy and resolution of the various images, in addition to developing an optimal processing flow.The data were initially processed with standard steps that included gain enhancement, dewow and temporal-filtering, background suppression, and 2D migration. Various radar velocities were used in the 2D migration and ultimately 0.12 m/ns was used. The data are complicated by multipathing from the surface and between culverts (from modeling). Some of this is ameliorated via deconvolution. The top of each of the four culverts was evident in the GPR images acquired with the 250 MHz and 100 MHz antennas. For 1 GHz, the top of the culvert was not clear due to the signal's attenuation. The 250 MHz shielded antenna provides a vertical resolution of about 0.1 m and is the choice to image the culverts. The 100 MHz antenna provided an increment in depth of penetration, but at the expense of a substantially diminished resolution (0.25 m).

Abdul Aziz, A.; Stewart, R. R.; Green, S. L.

2013-12-01

116

Heat transfer enhancement in three-dimensional corrugated channel flow  

Microsoft Academic Search

The effect of three-dimensional hydrodynamics on the enhancement of steady, laminar heat transfer in corrugated channels is studied using a combination of analytical and numerical techniques. Reynolds numbers are considered in the range of 0 < Re < 250 to avoid unsteady flow. Two-dimensional sinusoidal corrugations with flow perpendicular to the corrugations is taken as the base. The heat transfer

David R. Sawyers; Mihir Sen; Hsueh-Chia Chang

1998-01-01

117

Fish Passage Effectiveness of Recently Constructed Road Crossing Culverts in the Puget Sound Region of Washington State  

Microsoft Academic Search

Fish passage barriers at road–stream crossings are widely recognized as salmon Oncorhynchus spp. habitat restoration priorities in Washington State and throughout the Pacific Northwest of the USA. More than 3,500 fish passage barriers (mostly culverts) have been repaired in Washington streams since 1999, costing more than US$139 million. We evaluated fish passage at 77 randomly selected culverts (new and repaired)

David M. Price; Timothy Quinn; Robert J. Barnard

2010-01-01

118

Stereolithographed MM-wave corrugated horn antennas  

Microsoft Academic Search

We describe the fabrication and testing of corrugated horn antennas designed for operation in the W-band (75–110 GHz). These antennas are constructed using stereolithography and plated with copper. They demonstrate return loss < ?20 dB across most of the band and main beam patterns nearly identical with electroformed horns of the same design.

Peter T. Timbiea; John Gradeb; Daniel van der Weidebc; Bruno Maffeid; Giampaolo Pisanod

2011-01-01

119

Development of repetitive corrugation and straightening  

Microsoft Academic Search

In this paper, we present recent developments in repetitive corrugation and straightening (RCS), a new severe plastic deformation (SPD) technique. Two refinements of the original RCS method are presented and results are shown for commercial purity copper that illustrate the associated improvements in the effectiveness of nanostructuring. Second-generation tooling was implemented using a bench scale rolling mill for continuous processing

Jianyu Huang; Yuntian T. Zhu; David J. Alexander; Xiaozhou Liao; Terry C. Lowe; Robert J. Asaro

2004-01-01

120

Tuneable molecular doping of corrugated graphene  

Microsoft Academic Search

Density functional theory (DFT) modeling of the physisorption of four different types of molecules (toluene, bromine dimmer, water and nitrogen dioxide) over and above graphene ripples has been performed. For all types of molecules changes of charge transfer and binding energies in respect to flat graphene is found. The changes in electronic structure of corrugated graphene and turn of {\\\\pi}-orbitals

D. W. Boukhvalov

2010-01-01

121

Tuneable molecular doping of corrugated graphene  

Microsoft Academic Search

Density functional theory (DFT) modeling of the physisorption of four different types of molecules (toluene, bromine dimmer, water and nitrogen dioxide) over and under graphene ripples has been performed. For all types of molecules changes of charge transfer and binding energies in respect to flat graphene are found. The changes in the electronic structure of corrugated graphene and turn of

D. W. Boukhvalov

2010-01-01

122

Corrugated metal plate bridge with composite concrete structure  

US Patent & Trademark Office Database

A light to medium-duty bridge structure suitable for use in golf-courses, parks and similar settings. The bridge structure comprises at least one corrugated metal plate having corrugations oriented parallel to the longitudinal axis of the bridge structure. Applied to the upper surface of this corrugated metal plate is a layer of concrete or like material to provide a support/running surface. The corrugated metal plate is provided with a plurality of devices adapted to engage the concrete or like material so as to provide a composite corrugated metal plate-concrete structure capable of supporting light to medium-duty loads.

2011-01-04

123

Open top culverts as an alternative drainage system to minimize ecological effects in earth roads.  

NASA Astrophysics Data System (ADS)

During the last fifteen years a research team from School of Forestry at the Technical University of Madrid (Spain) has developed several competitive research projects regarding forest roads and open top culverts. A first approach was established with a prototype of 7 meters length in a hydraulic channel at the laboratory determining main parameters of different open top culverts in relation to different sizes of gravels and the self washing properties relationship with different slopes up to 8 %. The curves obtained may help to properly install these drainage systems avoiding maintenance costs. In addition more targeted pilot studies were developed in different forest earth roads in center and north Spain. The construction of the stations under study was financed by the U.P.M and the R&D National Plan. The main outcomes relates the low variation of humidity in a 20 m. wide range at both sides of the open top culverts and several considerations relating the angle of installation, the spacing of such drainage systems and the benefits against rilling along the roads. Also the erosion produced downhill was established and some construction methods to avoid adverse ecological effects. The diffusion of results includes congresses and a small booklet with a great acceptance in forestry services. Also a patent (ES 2 262 437) of an advanced model has been registered.

García, Jose L.; Elorrieta, Jose; Robredo, Jose C.; García, Ricardo; García, Fernando; Gimenez, Martin C.

2013-04-01

124

A 2-GHz Rectangular Corrugated Horn  

SciTech Connect

We have designed, constructed and tested a large, rectangular horn antenna with a center frequency of 2.0 GHz, corrugated on the E-plane walls, made out of aluminum sheet. A new technique has been developed to solder thin aluminum strips onto the back plane to form the corrugations. The radiation beam pattern shows half-power beamwidths of 12{sup 0} and 14{sup 0} in the H and E planes respectively, and side lobe response below -40 dB at angles greater than 50{sup 0} from horn axis. The measured return loss is less than -20 dB (VSWR < 1.22) between 1.7 and 2.3 GHz; insertion loss is less than 0.15 dB.

Bersanelli, M.; Bensadoun, M.; De Amici, Giovanni; Limon, M.; Smoot, George F.; Tanaka, S.; Witebsky, C.; Yamada, J.

1991-10-01

125

Microwave Pulse Compression using Helically Corrugated Waveguides  

Microsoft Academic Search

Cylindrical waveguide with a helical corrugation on the inner surface has proven an effective dispersive medium for the compression of smoothly frequency modulated microwave pulses. This paper presents the results of experiments where ~5.6kW, X-band (8.0GHz to 12.5GHz), microwave pulses of 80ns duration and 5% frequency modulation were compressed into 1.5ns pulses with 25 times higher peak power

A. R. Young; K. Ronald; P. MacInnes; C. G. Whyte; G. W. Burt; W. He; L. V. Konoplev; A. D. R. Phelps; A. W. Cross; S. V. Samsonov; V. L. Bratman; G. G. Denisov

2006-01-01

126

5-fold helically corrugated waveguide dispersion measurements  

Microsoft Academic Search

The results of 3-fold helically corrugated waveguide microwave pulse compression experiments are presented. A pulse of 80 ns duration having a power of 5.6 kW is compressed into a 140 kW peak power pulse of 1.5 ns duration. To enhance the power capabilities of the microwave pulse compressor a larger diameter 5fold helical waveguide structure was studied; the eigenwave dispersion

M. McStravick; K. Ronald; S. V. Samsonov; S. V. Mishakin; W. He; G. G. Denisov; C. G. Whyte; A. R. Young; V. L. Bratman; C. W. Robertson; A. W. Cross; N. G. Kolganov; A. D. R. Phelps; P. MacInnes

2010-01-01

127

Comparison of heat and mass transfer in different heat exchanger geometries with corrugated walls  

Microsoft Academic Search

In systematic comparative analyses heat exchangers with corrugated walls are analysed. The wall corrugation is generated by sinusoidally shaped walls as well as by crosswise corrugated cylinders of different cross-section on plane walls like those being used as spacers in membrane technology.Corrugated structures in crosswise orientation are composed of passages formed by layers of corrugated structures with opposite orientation of

C Zimmerer; P Gschwind; G Gaiser; V Kottke

2002-01-01

128

Formulae for the Buckling of Simply-Supported Corrugated Panels of Orthotropic Material under Shear Load.  

National Technical Information Service (NTIS)

This report presents formulae for the shear buckling of corrugated panels made of orthotropic materials. The formulae developed are to be incorporated in COPANO, a computer program for corrugated panel analysis and optimization. The corrugated panels cons...

P. G. van Bladel

1993-01-01

129

Performance of zigzag corrugated furrows in Bolivia  

NASA Astrophysics Data System (ADS)

In Bolivia, irrigation area is estimated in more than 250000 ha, being surface irrigation the most common method. In highland areas (Altiplano) and in interandean valleys, traditional and ancestral irrigation systems such as flood irrigation, contour furrows, zigzag corrugated furrows, suka kollus and irrigation by kanis, are the most important. In the case of very steep terrains and shallow soils, the zigzag corrugated irrigation method is very frequent. This irrigation method has been used for a long time but their low application efficiency and the shortage of water justify this work devoted to their characterization and to study their performance. The experimental study was conducted southeast of the city of La Paz in the community of Cebollino located at 2600 meters above sea level. Furrow characteristics vary in function of crop type and soil slope, so that the larger the slope the greater the separation between furrows. In our case, the crop chosen was the lettuce and the experimental plot had an area of 800 m2 with a slope ranging between 14 and 18%. Blocks of corrugated furrows were identified and experimental measures were made during each irrigation, once per week, in the central blocks to avoid border effects. To determine advance curves 15 stations were used spaced 18 m. At each station, advance and recession time and infiltration depth were measured. Inlet and outlet flow were controlled each 5 min. To calculate the reference evapotranspiration, the Hargraves-Samani equation was used. Due to the very high terrain slopes, the advance curve takes a linear form rather than the typical exponential form. This hinders the proper calculation of the parameters of the Kostiakov-Lewis equation used to determine the infiltrated depth values. The inlet flow range, along irrigation events, between 0.01 and 0.085 L/s due to the uncontrolled use of water in fields located upstream. The large variability of inflow flow difficult irrigation management especially in regard to the system organization and operation.

Roldán Cañas, J.; Chipana, R.; Moreno-Pérez, M. F.; Chipana, G.

2012-04-01

130

Hydraulic Flow Resistance Factors for Corrugated Metal Conduits.  

National Technical Information Service (NTIS)

This manual provides the designer with usable means for estimating the hydraulic resistance factors for five different corrugation shapes used in annular C.M.P. and four different corrugation shapes used in helical C.M.P. and enables the designer to estim...

J. N. Normann

1980-01-01

131

E-plane flared rectangular corrugated horn for tapered aperture  

Microsoft Academic Search

A flared rectangular horn is corrugated along the E-plane flaring walls. The corrugations are in the form of rectangular grooves parallel to the horn axis. The depths of the grooves are optimized to produce the tapered aperture that is needed for certain radiation pattern requirements. Two designs are presented in this paper. The first design is for a narrow beam

Amir I. Zaghloul; Theodore Anthony

2008-01-01

132

Water absorption in horizontal corrugated boards under water sprays  

Microsoft Academic Search

Experiments were performed to determine the water absorption propensity of four different corrugated boards oriented horizontally and exposed to vertical water sprays from above. The corrugated samples used in the experiments were taken from cartons and partition boards from the FM Global Standard Plastic Commodity and from the inner and outer cartons of the FM Global Class II Commodity. These

T. M. Jayaweera; H.-Z. Yu

2006-01-01

133

Dipole-excited short backfire antenna with corrugated rim  

Microsoft Academic Search

This letter reports results of an experimental study at X-band of a dipole-excited short backfire antenna having corrugations on the main reflector rim. The results obtained show that the presence of the corrugations can lead to improved antenna gain and sidelobe levels

P. S. Kooi; M. S. Leong; T. S. Yeo

1979-01-01

134

A linear model for the corrugation of rails  

Microsoft Academic Search

A linear model for the corrugation of rails is described. The study of a transfer function between the initial wheel and rail roughness and the wear rate spectra in the contact patch is presented. Under some conditions, depending on mean creepages, wheelset and track parameters, the initial roughness on the rail is shown to degenerate into corrugation in some frequency

E. Tassilly; N. Vincent

1991-01-01

135

Biased Brownian motion in extremely corrugated tubes.  

PubMed

Biased Brownian motion of point-size particles in a three-dimensional tube with varying cross-section is investigated. In the fashion of our recent work, Martens et al. [Phys. Rev. E 83, 051135 (2011)] we employ an asymptotic analysis to the stationary probability density in a geometric parameter of the tube geometry. We demonstrate that the leading order term is equivalent to the Fick-Jacobs approximation. Expression for the higher order corrections to the probability density is derived. Using this expansion orders, we obtain that in the diffusion dominated regime the average particle current equals the zeroth order Fick-Jacobs result corrected by a factor including the corrugation of the tube geometry. In particular, we demonstrate that this estimate is more accurate for extremely corrugated geometries compared with the common applied method using a spatially-dependent diffusion coefficient D(x, f) which substitutes the constant diffusion coefficient in the common Fick-Jacobs equation. The analytic findings are corroborated with the finite element calculation of a sinusoidal-shaped tube. PMID:22225392

Martens, S; Schmid, G; Schimansky-Geier, L; Hänggi, P

2011-12-01

136

Water quality effectiveness of ditch fencing and culvert crossing in the Lake Okeechobee basin, southern Florida, USA  

Microsoft Academic Search

Ditch fencing and culvert cattle crossing Best Management Practice (BMP) was evaluated in this study with regard to phosphorus (P) and nitrogen (N) load reductions and economic feasibility in the Lake Okeechobee (LO) basin. The BMP was implemented at a 170m section of a drainage ditch within a ranch in the LO basin and flow and concentration (N and P)

S. Shukla; D. Goswami; W. D. Graham; A. W. Hodges; M. C. Christman; J. M. Knowles

2011-01-01

137

An Evaluation of the Use of Critical Swimming Speed for Determination of Culvert Water Velocity Criteria for Smallmouth Bass  

Microsoft Academic Search

Critical swimming speed (Ucrit) is a common measure of the relationship between exercise intensity and duration within the prolonged performance envelope. This relationship is often used to establish water velocity criteria for fishways and culverts; however, the technique involves the assumptions that fish will choose to move at (1) a swimming speed equivalent to Ucrit and (2) a ground speed

Stephan Peake

2004-01-01

138

Heat Pipes  

ERIC Educational Resources Information Center

Describes the construction, function, and applications of heat pipes. Suggests using the heat pipe to teach principles related to heat transfer and gives sources for obtaining instructional kits for this purpose. (GS)

Lewis, J.

1975-01-01

139

Pipe Dreams.  

ERIC Educational Resources Information Center

Discusses the importance of attention to plumbing in college facilities, offering examples from various campuses. Addresses preventive maintenance, technology, and piping materials, including the debate between cast iron and PVC for drain pipes. (EV)

Milshtein, Amy

2002-01-01

140

Composite corrugated structures for morphing wing skin applications  

NASA Astrophysics Data System (ADS)

Composite corrugated structures are known for their anisotropic properties. They exhibit relatively high stiffness parallel (longitudinal) to the corrugation direction and are relatively compliant in the direction perpendicular (transverse) to the corrugation. Thus, they offer a potential solution for morphing skin panels (MSPs) in the trailing edge region of a wing as a morphing control surface. In this paper, an overview of the work carried out by the present authors over the last few years on corrugated structures for morphing skin applications is first given. The second part of the paper presents recent work on the application of corrugated sandwich structures. Panels made from multiple unit cells of corrugated sandwich structures are used as MSPs in the trailing edge region of a scaled morphing aerofoil section. The aerofoil section features an internal actuation mechanism that allows chordwise length and camber change of the trailing edge region (aft 35% chord). Wind tunnel testing was carried out to demonstrate the MSP concept but also to explore its limitations. Suggestions for improvements arising from this study were deduced, one of which includes an investigation of a segmented skin. The overall results of this study show that the MSP concept exploiting corrugated sandwich structures offers a potential solution for local morphing wing skins for low speed and small air vehicles.

Thill, C.; Etches, J. A.; Bond, I. P.; Potter, K. D.; Weaver, P. M.

2010-12-01

141

Single and dual-band multimode hard horn antennas with partly corrugated walls  

Microsoft Academic Search

We introduce a partly corrugated hard horn, consisting of a smooth-walled horn with an attached longitudinally corrugated outer section. This alleviates the problems with the manufacturing when the longitudinal corrugations extend into the throat of the horn. The transition between the inner smooth walled part and the outer corrugated part is abrupt. This is used and controlled to design better

Omid Sotoudeh; Per-Simon Kildal; Per Ingvarson; Sergei P. Skobelev

2006-01-01

142

Fatigue testing of corrugated and Teflon hoses  

NASA Technical Reports Server (NTRS)

Single and two-phase heat transport systems for the thermal control of large space facilities require fluid lines that traverse joints and either rotate or move in some other manner. Flexible hoses are being considered as one means of traversing these joints. To test the resilience of flexible hoses to bending stress, a test assembly was constructed to determine the number of flexing cycles the hoses could withstand before losing their ability to maintain a constant pressure. Corrugated metal hoses and Teflon hoses were tested at different pressures with nitrogen gas. The metal hoses had lives ranging from 30,000 to 100,000 flexing cycles. But, even after 400,000 cycles, the Teflon hoses remained essentially intact, though some leakage in the convoluted Teflon is noted.

Benner, Steve M.; Swanson, Theodore D.; Costello, Frederick A.

1990-01-01

143

Surface corrugations influence monolayer graphene electromagnetic response  

NASA Astrophysics Data System (ADS)

We consider the corrugated monolayer graphene membrane electromagnetic response in terahertz range. We study the generated in irradiated graphene total current (from both valleys) taking into account for the first time both the synthetic electric fields arising due to the (inevitable) presence in graphene of inherent out-of-plane nanodeformations and the double-valleys energy spectrum of Dirac charge particles. Our approach is based on atomistic quantum mechanics used for the description of (1) the valence ?-? bonds changes generated by activating external periodic electric field and also (2) the mechanism of Dirac electron interaction with this time-dependent perturbation. We consider the problem in the framework of the model of noninteracting Dirac electrons. Assuming surface corrugations not to be very rough we obtain for weak fields the formula for the total current induced in graphene membrane. Our formula describes the curved current paths in the linear in E(t) approximation for the given graphene surface form. We show that the local direction of current paths is determined by the synthetic electric field whose direction may essentially differ from the one of the external field and depends on the local curvature of the graphene membrane. We also demonstrate that valley currents generated by a linearly external field have nonzero elliptic polarization angles depending on the point (x,y). Valley currents are shown to rotate in opposite directions in different valleys. The results obtained below can be applied to the analysis of different devices in terahertz optics and optoelectronics and the imaging experiments at the Dirac point.

Firsov, Yu. A.; Firsova, N. E.

2014-08-01

144

Designs and applications of corrugated QWIPs  

NASA Astrophysics Data System (ADS)

In this paper, we will describe the performance of two long wavelength 1024 × 1024 corrugated quantum well infrared photodetector focal plane arrays (C-QWIP FPAs) with cutoff wavelengths at 8.6 and 9.0 ?m, respectively. The FPAs are background limited (BLIP) at around 76 K in an f/1.8 optical system. In addition to the high performance of these C-QWIPs, the corresponding FPAs are also easily producible, making them ideal for large production. We will discuss the optimization of the detectors for different applications. Since corrugated coupling is wavelength insensitive, it is capable of broadband and multi-color detection. We will present a GaAs/AlGaAs broadband detector based on a binary superlattice design. Incorporating the broadband characteristic in a high gain InGaAs/InP material, C-QWIPs with large background photocurrent can be obtained for high speed applications. For multi-color detection, we have investigated two different approaches. One is based on a voltage-tunable, two-color QWIP material, which can be switched between two detection wavelengths simply by changing the detector bias. Stacking two of these similar QWIPs together and separating them with a middle contact layer, a voltage tunable, four-color detector array can be fabricated. A second approach is to combine a broadband QWIP material with a wavelength-selective light coupling method. Using a light coupling geometry to control the detection wavelength of individual pixels, a large number of wavelengths can be detected based on a single broadband detector material.

Choi, K. K.; Monroy, C.; Goldberg, A.; Dang, G.; Jhabvala, M.; La, A.; Tamir, T.; Leung, K. M.; Majumdar, A.; Li, Jinjin; Tsui, D. C.

2005-10-01

145

Fabrication of corrugated Ge-doped silica fibers.  

PubMed

We present a method of fabricating Ge-doped SiO2 fibers with corrugations around their full circumference for a desired length in the longitudinal direction. The procedure comprises three steps: hydrogenation of Ge-doped SiO2 fibers to increase photosensitivity, recording of Bragg gratings with ultraviolet light to achieve modulation of refractive index, and chemical etching. Finite-length, radially corrugated fibers may be used as couplers. Corrugated tapered fibers are used as high energy throughput probes in scanning near-field optical microscopy. PMID:22714512

Wróbel, P; Stefaniuk, T; Antosiewicz, T J; Libura, A; Nowak, G; Wejrzanowski, T; Andrzejczuk, M; Kurzyd?owski, K J; Jedrzejewski, K; Szoplik, T

2012-06-18

146

Diverse corrugation pattern in radially shrinking carbon nanotubes  

SciTech Connect

Stable cross sections of multiwalled carbon nanotubes subjected to electron-beam irradiation are investigated in the realm of the continuum mechanics approximation. The self-healing nature of sp{sup 2} graphitic sheets implies that selective irradiation of the outermost walls causes their radial shrinkage with the remaining inner walls undamaged. The shrinking walls exert high pressure on the interior part of nanotubes, yielding a wide variety of radial-corrugation patterns (i.e., circumferentially wrinkling structures) in the cross section. All corrugation patterns can be classified into two deformation phases for which the corrugation amplitudes of the innermost wall differ significantly.

Shima, Hiroyuki; Sato, Motohiro; Iiboshi, Kohtaroh; Ghosh, Susanta; Arroyo, Marino [Division of Applied Physics, Faculty of Engineering, Hokkaido University, Sapporo, Hokkaido 060-8628, Japan and Department of Applied Mathematics 3, LaCaN, Universitat Politecnica de Catalunya, Barcelona 08034 (Spain); Division of Socio-Environmental Engineering, Faculty of Engineering, Hokkaido University, Sapporo, Hokkaido 060-8628 (Japan); Division of Socio-Environmental Engineering, Graduate School of Engineering, Hokkaido University, Sapporo, Hokkaido 060-8628 (Japan); Department of Applied Mathematics 3, LaCaN, Universitat Politecnica de Catalunya, Barcelona 08034 (Spain)

2010-08-15

147

Demonstration of Angle-Dependent Casimir Force between Corrugations  

NASA Astrophysics Data System (ADS)

The normal Casimir force between a sinusoidally corrugated gold coated plate and a sphere was measured at various angles between the corrugations using an atomic force microscope. A strong dependence on the orientation angle of the corrugation is found. The measured forces were found to deviate from the proximity force approximation and are in agreement with the theory based on the gradient expansion including correlation effects of geometry and material properties. We analyze the role of temperature. The obtained results open new opportunities for control of the Casimir effect in micromechanical systems.

Banishev, A. A.; Wagner, J.; Emig, T.; Zandi, R.; Mohideen, U.

2013-06-01

148

Demonstration of angle-dependent Casimir force between corrugations.  

PubMed

The normal Casimir force between a sinusoidally corrugated gold coated plate and a sphere was measured at various angles between the corrugations using an atomic force microscope. A strong dependence on the orientation angle of the corrugation is found. The measured forces were found to deviate from the proximity force approximation and are in agreement with the theory based on the gradient expansion including correlation effects of geometry and material properties. We analyze the role of temperature. The obtained results open new opportunities for control of the Casimir effect in micromechanical systems. PMID:23829717

Banishev, A A; Wagner, J; Emig, T; Zandi, R; Mohideen, U

2013-06-21

149

Plasma outflow from a corrugated trap in the kinetic regime  

SciTech Connect

The problem of stationary plasma outflow from an open corrugated trap in the kinetic regime is considered with allowance for pair collisions in the framework of a kinetic equation with the Landau collision integral. The distribution function is studied in the limit of small-scale corrugation and a large mirror ratio. In considering a single corrugation cell, a correction for the distribution function is calculated analytically. An equation describing variations of the distribution function along the system is derived and used to study the problem of plasma outflow into vacuum.

Skovorodin, D. I.; Beklemishev, A. D. [Russian Academy of Sciences, Budker Institute of Nuclear Physics, Siberian Branch (Russian Federation)

2012-03-15

150

Propagation and radiation characteristics of a multimode corrugated waveguide feedhorn  

NASA Technical Reports Server (NTRS)

A prototype of the multimode corrugated feedhorn which will be used in the 400 kW CW Ka-band radar system is described. A rough design is done using coupled mode theory and standard corrugated waveguide modes. A more exact analysis using mode matching techniques is then used which takes into account the effect of a finite number of corrugations per wavelength and determines the modes which are reflected from the device. A prototype feedhorn has been constructed and measured. These experimental results are then compared to the theoretical predictions which agree satisfactorily closely.

Hoppe, D.

1985-01-01

151

OBLIQUE VIEW OF POWERHOUSE OFFICE AND CORRUGATED METALCLAD MAINTENANCE BUILDING, ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

OBLIQUE VIEW OF POWERHOUSE OFFICE AND CORRUGATED METAL-CLAD MAINTENANCE BUILDING, LOOKING WEST 90mm lens - Tule River Hydroelectric Complex, CA Highway 190 at North Fork of Middle Fork of Tule River, Springville, Tulare County, CA

152

Boiling Heat Transfer in Falling Film Evaporators with Corrugated Surfaces.  

National Technical Information Service (NTIS)

Boiling heat transfer coefficients were determined for falling film evaporation on corrugated surfaces. The local coefficients varied much more from peak to valley with deionized water than with saline water, probably becuase of poorer wetting by deionize...

G. Jansen P. C. Owzarski

1971-01-01

153

Test and Evaluation of Cleated Corrugated Plastic Containers.  

National Technical Information Service (NTIS)

Testing and evaluation was conducted of a new concept for substituting a corrugated plastic material for plywood in containers otherwise constructed in accordance with Federal Specification PPP-B-601. The purpose of the new cleated plastic container conce...

P. Quijas

1986-01-01

154

Heat-transfer performance of corrugated-tube thermosiphons. Part 2; Condenser performance  

SciTech Connect

A two-phase closed thermosiphon made of a corrugated tube was developed to extend the application field of heat pipes. In the first paper, the thermal performance of the evaporator section was examined with the thermosiphons set vertical or tilted. The paper describes the thermal performance of the condenser section. A condensation heat-transfer coefficient is proposed as a function of Nusselt's theory modified by three parameters: the Lockhart--Martinelli parameter to consider the effect of vapor flow on the condensing surface, and two new parameters concerned with the effects of the inclination angle of the thermosiphon and the fill charge ratio of the working fluid. The former parameter has a linear relation with the condensation heat-transfer coefficient, and the latter two have a quadratic relation.

Hirashima, M.; Nishikawa, Y.; Taguchi, M. (Takuma Research and Development Co., Ltd. (JP)); Negishi, K. (Tokyo Metropolitan Inst. of Technology (JP)); Kaneko, K. (Univ. of Osaka Prefecture (JP)); Matsuoka, T. (Nissan Motor Co., Ltd. (JP))

1991-01-01

155

Quantum wells with corrugated interfaces: Theory of electron states  

NASA Astrophysics Data System (ADS)

We present realistic effective-mass calculations of electron and exciton states in [311] GaAs/AlAs corrugated quantum wells (QW's) taking into consideration a finite barrier potential and flux-conserving boundary conditions. One-dimensional minibands are formed in the periodic lateral corrugation potential. Light- and heavy-hole exciton binding energies are calculated as a function of QW effective width and discussed in connection with existing experimental data.

Kiselev, A. A.; Rössler, U.

1994-11-01

156

Corrugated glass–ceramics from LZSA cast tapes  

Microsoft Academic Search

The aim of this work was to fabricate corrugated lightweight structures from green tapes of Li2O–ZrO2–SiO2–Al2O3 (LZSA) glass–ceramics. The green tapes were cast, thermopressed, corrugated, and sintered at 800°C for 1h, yielding low porous and homogenous microstructures confirmed by electron microscopy analysis. Dilatometric analysis demonstrated three linear regions, each one exhibiting a specific thermal expansion coefficient (TEC) in the 25–800°C

Tina Hausöl; Cynthia M. Gomes; Hansu Birol; Antonio P. N. Oliveira; Dachamir Hotza; Nahum Travitzky; Peter Greil

2010-01-01

157

Heat Pipes  

NASA Technical Reports Server (NTRS)

Phoenix Refrigeration Systems, Inc.'s heat pipe addition to the Phoenix 2000, a supermarket rooftop refrigeration/air conditioning system, resulted from the company's participation in a field test of heat pipes. Originally developed by NASA to control temperatures in space electronic systems, the heat pipe is a simple, effective, heat transfer system. It has been used successfully in candy storage facilities where it has provided significant energy savings. Additional data is expected to fully quantify the impact of the heat pipes on supermarket air conditioning systems.

1991-01-01

158

Piping Flexibility  

NASA Technical Reports Server (NTRS)

A NASA computer program aids Hudson Engineering Corporation, Houston, Texas, in the design and construction of huge petrochemical processing plants like the one shown, which is located at Ju'aymah, Saudi Arabia. The pipes handling the flow of chemicals are subject to a variety of stresses, such as weight and variations in pressure and temperature. Hudson Engineering uses a COSMIC piping flexibility analysis computer program to analyze stresses and unsure the necessary strength and flexibility of the pipes. This program helps the company realize substantial savings in reduced engineering time.

1978-01-01

159

Directional and enhanced spontaneous emission with a corrugated metal probe.  

PubMed

A three-dimensional corrugated metal tapered probe with surface corrugated gratings at the tip apex is proposed and investigated theoretically, which leads to an obvious emission beaming effect of spontaneous emission from a single emitter near the probe. In contrast with conventional apertureless metal probes, where only the enhancement of an optical near-field is concerned, the corrugated probe is able to manipulate local excitation intensity and far-field emission direction simultaneously. The angular emission from a single dipole source, being placed close to the corrugated probe, falls into a cone with a maximum directivity angle of ±11.6°, which improves the collection efficiency 25-fold. Such a probe simultaneously increases the localized field intensity to about twice as strong as the conventional bare tip. In addition, the radiation pattern is sensitive to the working wavelength and the dipole to tip-apex separation. These findings make a promising route to the development of plasmonic spontaneous emission manipulation based on corrugated tapered antenna-for instance, tip-enhanced spectroscopy, single-molecule sensing, and single-photon source . PMID:24887425

Shen, Hongming; Lu, Guowei; He, Yingbo; Cheng, Yuqing; Liu, Haitao; Gong, Qihuang

2014-06-12

160

Finite-temperature Casimir force between perfectly metallic corrugated surfaces  

SciTech Connect

We study the Casimir force between two corrugated plates due to thermal fluctuations of a scalar field. For arbitrary corrugations and temperature T, we provide an analytical expression for the Casimir force, which is exact to second order in the corrugation amplitude. We study the specific case of two sinusoidally corrugated plates with corrugation wavelength {lambda}, lateral displacement b, and mean separation H. We find that the lateral Casimir force is F{sub l}(T,H)sin(2{pi}b/{lambda}). In other words, at all temperatures, the lateral force is a sinusoidal function of the lateral shift. In the limit {lambda}>>H, F{sub l}(T{yields}{infinity},H){proportional_to}k{sub B}TH{sup -4}{lambda}{sup -1}. In the opposite limit {lambda}<

Sarabadani, Jalal; Miri, MirFaez [Department of Physics, University of Isfahan, Isfahan 81746 (Iran, Islamic Republic of); Department of Physics, University of Tehran, P.O. Box 14395-547, Tehran (Iran, Islamic Republic of) and School of Physics, Institute for Research in Fundamental Sciences, (IPM) Tehran 19395-5531 (Iran, Islamic Republic of)

2011-09-15

161

Directional and enhanced spontaneous emission with a corrugated metal probe  

NASA Astrophysics Data System (ADS)

A three-dimensional corrugated metal tapered probe with surface corrugated gratings at the tip apex is proposed and investigated theoretically, which leads to an obvious emission beaming effect of spontaneous emission from a single emitter near the probe. In contrast with conventional apertureless metal probes, where only the enhancement of an optical near-field is concerned, the corrugated probe is able to manipulate local excitation intensity and far-field emission direction simultaneously. The angular emission from a single dipole source, being placed close to the corrugated probe, falls into a cone with a maximum directivity angle of +/-11.6°, which improves the collection efficiency 25-fold. Such a probe simultaneously increases the localized field intensity to about twice as strong as the conventional bare tip. In addition, the radiation pattern is sensitive to the working wavelength and the dipole to tip-apex separation. These findings make a promising route to the development of plasmonic spontaneous emission manipulation based on corrugated tapered antenna--for instance, tip-enhanced spectroscopy, single-molecule sensing, and single-photon source .

Shen, Hongming; Lu, Guowei; He, Yingbo; Cheng, Yuqing; Liu, Haitao; Gong, Qihuang

2014-06-01

162

Novel low-cost technique to manufacture submillimeter corrugated feedhorns  

NASA Astrophysics Data System (ADS)

Corrugated feedhorns are commonly used with reflector antennas, either for emission or reception purposes, because of their very low side lobe beam patterns, their very good E-H plane symmetry and their important bandwidth. Unfortunately, the electroforming technique that is generally used to fabricate them requires the machining of single-use mandrel. Direct milling of the horn is also possible, either in a single block or in a split block, but this also requires to machine each desired horn. At submillimeter frequencies, machining of small corrugations in a mandrel or in a block is costly. We present in this paper a cost-effective technique to fabricate helicoidal corrugated feed horns, which consists in machining one reusable mandrel and to mold as many horns as needed.

Munier, Jean-Marie; Maestrini, A.; Salez, Morvan C.; Guillon, Matthieu; Marchand, B.

2000-07-01

163

Dynamic stability of crack fronts: out-of-plane corrugations.  

PubMed

The dynamics and stability of brittle cracks are not yet fully understood. Here we use the Willis-Movchan 3D linear perturbation formalism [J. Mech. Phys. Solids 45, 591 (1997)] to study the out-of-plane stability of planar crack fronts in the framework of linear elastic fracture mechanics. We discuss a minimal scenario in which linearly unstable crack front corrugations might emerge above a critical front propagation speed. We calculate this speed as a function of Poisson's ratio and show that corrugations propagate along the crack front at nearly the Rayleigh wave speed. Finally, we hypothesize about a possible relation between such corrugations and the long-standing problem of crack branching. PMID:23383795

Adda-Bedia, Mokhtar; Arias, Rodrigo E; Bouchbinder, Eran; Katzav, Eytan

2013-01-01

164

Aerothermodynamic Assessment of Corrugated Panel Thermal Protection Systems  

NASA Technical Reports Server (NTRS)

The feasibility of using corrugated panels as a thermal protection system for an advanced space transportation vehicle was investigated. The study consisted of two major tasks: development of improved correlations for wind tunnel heat transfer and pressure data to yield design techniques, and application of the design techniques to determine if corrugated panels have application future aerospace vehicles. A single-stage-to-orbit vehicle was used to assess advantages and aerothermodynamic penalties associated with use of such panels. In the correlation task, experimental turbulent heat transfer and pressure data obtained on corrugation roughened surfaces during wind tunnel testing were analyzed and compared with flat plate data. The correlations and data comparisons included the effects of a large range of geometric, inviscid flow, internal boundary layer, and bulk boundary layer parameters in supersonic and hypersonic flow.

Brandon, H. J.; Britt, A. H.; Kipp, H. W.; Masek, R. V.

1978-01-01

165

Compact Multimode Horn with Coaxial Corrugation for Circular Coverage  

NASA Astrophysics Data System (ADS)

For achieving low cross-polarization component in addition to circular-coverage pattern in compact structure, this paper proposes a novel multimode horn with arbitrary coaxial-corrugation configuration which plays two roles of mode converters and chokes. The proposed horn can be designed by iteration of non-linear optimization procedure based on generalized scattering matrices pre-calculated by the mode-matching technique. We show a compact horn with four coaxial corrugations for shaping circular-coverage beam over frequency range of bandwidth 20%. The effectiveness of the designed horn is discussed by evaluating VSWR and radiation characteristics in X-band numerically and experimentally.

Kobayashi, Takashi; Deguchi, Hiroyuki; Tsuji, Mikio; Omori, Kouhei

166

Corrugated metallodielectric superlattices via release-rollup assembly  

NASA Astrophysics Data System (ADS)

A `release-rollup' assembly (RRA) technique is described that yields corrugated metallodielectric superlattices. Bilayers of polymer/Au cast onto diffraction gratings are released and rolled into multilayers with registration of the stacked corrugations across mm-scales. Optical imaging reveals Moiré fringes with reflection spectra that track the bilayer thickness due to mis-stacking. Angular-resolved spectra show spectrally-modulated diffraction opposite to that of the metallic stop-bands, but which agrees with a simple model. This scalable fabrication strategy is thus widely exploitable for laterally patterned metamaterials and optical superlattices.

Gibbons, N.; Baumberg, J. J.

2011-08-01

167

Corrugated metallodielectric superlattices via release-rollup assembly.  

PubMed

A 'release-rollup' assembly (RRA) technique is described that yields corrugated metallodielectric superlattices. Bilayers of polymer/Au cast onto diffraction gratings are released and rolled into multilayers with registration of the stacked corrugations across mm-scales. Optical imaging reveals Moiré fringes with reflection spectra that track the bilayer thickness due to mis-stacking. Angular-resolved spectra show spectrally-modulated diffraction opposite to that of the metallic stop-bands, but which agrees with a simple model. This scalable fabrication strategy is thus widely exploitable for laterally patterned metamaterials and optical superlattices. PMID:21934922

Gibbons, N; Baumberg, J J

2011-08-01

168

Theory of a ubitron in a corrugated waveguide  

NASA Astrophysics Data System (ADS)

A K a band ubitron is currently under development at NRL using a corrugated waveguide and a helical wiggler. The corrugated waveguide is used for low-voltage operation. A 3-D nonlinear formulation has been derived, and a simulation code TARANTULA has been developed. The model treats HE and EH modes in the vacuum waveguide. No wiggler average is imposed on the electron dynamics. Preliminary calculations indicate that 20% bandwidth operation in K a band is possible at voltages of about 90 kV with a 7-8 mm period wiggler generating a 500-600 G transverse magnetic field. Detailed results of the theory and simulation will be presented.

Freund, H. P.; Nguyen, K.; Pershing, D. E.

1997-02-01

169

Dynamics of Surface Migration in the Weak Corrugation Regime  

NASA Astrophysics Data System (ADS)

We report a systematic study for metal-on-metal surface migration in the weak corrugation regime, i.e., with migration barriers falling below ~100 meV. The migration characteristics are elucidated by variable-temperature scanning tunneling microscopy observations in the 50-200 K temperature range, which are analyzed by means of nucleation theory. The results demonstrate that, upon entering the weak corrugation regime, the dynamics of the systems are characterized by increasingly reduced effective preexponential factors, while Arrhenius behavior prevails.

Barth, J. V.; Brune, H.; Fischer, B.; Weckesser, J.; Kern, K.

2000-02-01

170

Mode switching in a gyrotron with azimuthally corrugated resonator.  

PubMed

The operation of a gyrotron having a cylindrical resonator with an azimuthally corrugated wall is analyzed. In such a device, wall corrugation cancels the degeneracy of the modes with azimuthally standing patterns. The coupling between these modes depends on the radius of electron beam. It is shown that such a gyrotron can be easily switched from one mode to another. When the switching is done with the repetition frequency equal to the rotational frequency of magnetic islands, this sort of operation can be used for suppression of neoclassical tearing modes in large-scale tokamaks and stellarators. PMID:17677705

Nusinovich, G S; Sinitsyn, O V; Antonsen, T M

2007-05-18

171

Heat Pipes  

NASA Technical Reports Server (NTRS)

Bobs Candies, Inc. produces some 24 million pounds of candy a year, much of it 'Christmas candy.' To meet Christmas demand, it must produce year-round. Thousands of cases of candy must be stored a good part of the year in two huge warehouses. The candy is very sensitive to temperature. The warehouses must be maintained at temperatures of 78-80 degrees Fahrenheit with relative humidities of 38- 42 percent. Such precise climate control of enormous buildings can be very expensive. In 1985, energy costs for the single warehouse ran to more than $57,000 for the year. NASA and the Florida Solar Energy Center (FSEC) were adapting heat pipe technology to control humidity in building environments. The heat pipes handle the jobs of precooling and reheating without using energy. The company contacted a FSEC systems engineer and from that contact eventually emerged a cooperative test project to install a heat pipe system at Bobs' warehouses, operate it for a period of time to determine accurately the cost benefits, and gather data applicable to development of future heat pipe systems. Installation was completed in mid-1987 and data collection is still in progress. In 1989, total energy cost for two warehouses, with the heat pipes complementing the air conditioning system was $28,706, and that figures out to a cost reduction.

1990-01-01

172

Dual-band low-profile corrugated feeder antenna  

Microsoft Academic Search

A dual-operating-band planar horn antenna having very low profile is presented in this paper. By opening a subwavelength aperture into a corrugated conducting plate, good return losses and a narrow radiated beam in each of the two desired operating frequency bands can be measured. This behavior is very similar to that observed in optical wavelengths where enhanced transmission was measured

Miguel Beruete Díaz; I. Campillo; J. S. Dolado; J. E. Rodriguez-Seco; E. Perea; Francisco Falcone; Mario Sorolla Ayza

2006-01-01

173

Performance of a multi-frequency elliptical corrugated horn  

Microsoft Academic Search

An elliptical corrugated horn feeding a single offset-reflector antenna is being considered for an elliptical beam spacecraft antenna system with simultaneous uplink, downlink, and RF tracking capability. The performance of such a horn was measured for the fundamental modes over a wide frequency band and also for higher order tracking modes. The cross-polar response, copolar performance, and tracking pattern performance

D. J. Brain; Y. Kol

1985-01-01

174

OBLIQUE VIEW OF POWERHOUSE OFFICE AND CORRUGATED METALCLAD VEHICLE GARAGE ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

OBLIQUE VIEW OF POWERHOUSE OFFICE AND CORRUGATED METAL-CLAD VEHICLE GARAGE AND FUEL PUMP. MAINTENANCE BUILDING IS AT RIGHT CENTER. 90mm lens - Tule River Hydroelectric Complex, CA Highway 190 at North Fork of Middle Fork of Tule River, Springville, Tulare County, CA

175

Neutron Detection by Corrugated-Plate Spark Counters  

Microsoft Academic Search

Corrugated plates as spark counter electrodes provide well-defined discharge gaps with low operating voltages, analogous to the conditions more usually obtained in multiwire arrays. By inserting boric acid or a hydrogenous material into the grooves, sensitivity to thermal or fast neutrons may be obtained. For a more sensitive counter geometry, plastic strips have been mounted between the grooves of adjoining

G. G. Eichholz; W. M. Templeton

1966-01-01

176

Helically corrugated waveguides for compression of microwave pulses  

Microsoft Academic Search

Waveguide with a helical corrugation of the inner surface has the desirable properties of optimised dispersion, operation far from cut-off and high breakdown field strength which make it an excellent medium for passive pulse compression. New compression measurements at both milli-watt and kilowatt powers using an optimised frequency modulation of the input pulse will be presented and discussed.

M. McStravick; S. V. Samsonov; A. W. Cross; G. G. Denisov; W. He; P. MacInnes; A. D. R. Phelps; V. L. Bratman; K. Ronald; S. Mishakin; I. V. Konoplev; G. Burt; A. R. Young; C. G. Whyte

2008-01-01

177

Dispersion of helically corrugated waveguides: Analytical, numerical, and experimental study  

Microsoft Academic Search

Helically corrugated waveguides have recently been studied for use in various applications such as interaction regions in gyrotron traveling-wave tubes and gyrotron backward-wave oscillators and as a dispersive medium for passive microwave pulse compression. The paper presents a summary of various methods that can be used for analysis of the wave dispersion of such waveguides. The results obtained from an

G. Burt; S. V. Samsonov; K. Ronald; G. G. Denisov; A. R. Young; V. L. Bratman; A. D. Phelps; A. W. Cross; I. V. Konoplev; W. He; J. Thomson; C. G. Whyte

2004-01-01

178

Attenuation in a circular waveguide with helical corrugation  

NASA Astrophysics Data System (ADS)

Experimental results of attenuation properties for a circular waveguide with helical corrugation propagating the HE(11) mode are presented. Dispersion curve and attenuation values are obtained using classical cavity measurements. First results show a low attenuation and then such a structure would be convenient for antenna feeder applications.

Jecko, F.; Papiernik, A.

1980-10-01

179

Attenuation in a circular waveguide with helical corrugation  

Microsoft Academic Search

Experimental results of attenuation properties for a circular waveguide with helical corrugation propagating the HE(11) mode are presented. Dispersion curve and attenuation values are obtained using classical cavity measurements. First results show a low attenuation and then such a structure would be convenient for antenna feeder applications.

F. Jecko; A. Papiernik

1980-01-01

180

Bose Einstein condensate flow in a corrugated magnetic waveguide  

Microsoft Academic Search

The flow of a Bose Einstein condensate through smooth and corrugated waveguides is studied by direct numerical solution of the time-dependent Gross Pitaevskii equation. One end of each waveguide has a teacup longitudinal potential, which when lowered generates a quasi-continuous supersonic flow. As the nonlinear strength factor, which is proportional to the scattering length times the number of atoms, becomes

M. C. Witthoeft; M. S. Pindzola

2006-01-01

181

Evaluation of Highly Weather-Resistant Corrugated Fiberboard.  

National Technical Information Service (NTIS)

The study was conducted to determine the physical properties of a new 'highly weather-resistant' single-wall corrugated fiberboard material as compared to grade V3c of Federal Specification PPP-F-320 and to evaluate its material performance and container ...

P. T. Burke

1968-01-01

182

CLOSED PROCESS WATER LOOP IN NSSC CORRUGATING MEDIUM MANUFACTURE  

EPA Science Inventory

Over the last 5 years, the Green Bay Packaging corrugating medium mill has converted to an essentially closed process water system. The mill is a net consumer of water. This is due to the greater amount of water carried out of the system with the sheet compared to the lower water...

183

Magnetic Wave Interactions in a Periodically Corrugated YIG Film  

Microsoft Academic Search

The magnetic wave interactions in a YIG film having periodically corrugated surfaces are investigated for the ease of magnetization parallel to the propagation direction. By a singular boundary perturbation procedure, the coupled-mode equations governing the nature of the interactions are deduced and analyzed to obtain the characteristics of the interactions. Representative numerical results are presented to reveal the characteristics of

S. R. Seshadri

1979-01-01

184

Spoof Surface Plasmon Polariton Modes Propagating Along Periodically Corrugated Wires  

Microsoft Academic Search

In this paper, we analyze in detail the characteristics of surface electromagnetic modes that can propagate along a periodically corrugated, perfectly conducting wire. We show how these modes, termed spoof surface plasmon polaritons, resemble surface plasmon polaritons supported by metallic wires at optical frequencies. The important point is that the dispersion relation of spoof surface plasmon polaritons is mainly controlled

A. I. Fernandez-Dominguez; L. Martin-Moreno; F. J. Garcia-Vidal; S. R. Andrews; S. A. Maier

2008-01-01

185

Stress-Strain State of a Corrugated Cylindrical Shell  

Microsoft Academic Search

By using the relations of the Kirchhoff–Love theory of shells and the method of distortion of the shape of the boundary in the process of axisymmetric heating through the thickness of shells according to a linear law, we construct a solution of the problem of statics for a corrugated cylindrical shell in an axially symmetric temperature field under the action

O. I. Vasyunyk

2003-01-01

186

Heat Pipes  

NASA Technical Reports Server (NTRS)

Heat Pipes were originally developed by NASA and the Los Alamos Scientific Laboratory during the 1960s to dissipate excessive heat build- up in critical areas of spacecraft and maintain even temperatures of satellites. Heat pipes are tubular devices where a working fluid alternately evaporates and condenses, transferring heat from one region of the tube to another. KONA Corporation refined and applied the same technology to solve complex heating requirements of hot runner systems in injection molds. KONA Hot Runner Systems are used throughout the plastics industry for products ranging in size from tiny medical devices to large single cavity automobile bumpers and instrument panels.

1996-01-01

187

Condensation of refrigerants flowing inside smooth and corrugated tubes  

SciTech Connect

Because heat exchanger thermal performance has a direct fluence on the overall cycle performance of vapor-compression refrigeration machinery,enhanced heat transfer surfaces are of interest to improve the efficiency of heat pumps and air conditioners. We investigated R-22 and a nonazeotropic refrigerant mixture (NARM) of 75% R-143a and 25% R-124 (by mass) to study their thermal performance in a condenser made of conventional smooth tubes and another condenser made of corrugated, or spirally indented, tubes. We investigated the condensing heat transfer and pressure drop characteristics in an experimental test loop model of a domestic beat pump system employing a variable speed compressor. The refrigerant circulates inside the central tube and the water circulates in the annulus. At refrigerant mass fluxes of approximately 275--300 kg/m{sup 2}s, the measured irreversible pressure drop of the corrugated surface was 23% higher than that of the smooth surface for the R-22. At refrigerant mass fluxes of 350-370 kg/m{sup 2}s, the irreversible pressure drop of the corrugated surface was 36% higher than that of the smooth surface for the NARM. The average heat transfer coefficient for the corrugated surface for R-22 was roughly 40% higher than that for the smooth tube surface at refrigerant mass fluxes of 275--295 kg/m{sup 2}s. The average heat transfer coefficient for the corrugated surface for the NARM was typically 70% higher than that for the smooth tube surface at refrigerant mass fluxes of 340--385 kg/m{sup 2}s.

Hinton, D.L. [Tennessee State Univ., Nashville, TN (United States); Conklin, J.C.; Vineyard, E.A. [Oak Ridge National Lab., TN (United States)

1995-07-01

188

Porus electrode comprising a bonded stack of pieces of corrugated metal foil  

NASA Technical Reports Server (NTRS)

An electrode suitable for use in an electrochemical cell is described. The electrode is composed of a porous conductive support with a bonded stack of pieces of thin corrugated nickel foil where the corrugations are oriented approximately perpendicular to the sides of the electrode and form an array of passages through the electrode. Active material such as cadmium hydroxide or nickel hydroxide is uniformly distributed within the passages. The support may comprise also a piece of thin flat nickel foil between adjacent pieces of the corrugated foil, forming a barrier between the passages formed on each side of it. Typically the corrugations in the odd corrugated layers are oriented at a small angle from the perpendicular in one direction and the corrugations in the even corrugated layers are oriented at a small angle from the perpendicular in the opposite direction.

Mccallum, J. (inventor)

1973-01-01

189

Test of superplastically formed corrugated aluminum compression specimens with beaded webs  

NASA Technical Reports Server (NTRS)

Corrugated wall sections provide a highly efficient structure for carrying compressive loads in aircraft and spacecraft fuselages. The superplastic forming (SPF) process offers a means to produce complex shells and panels with corrugated wall shapes. A study was made to investigate the feasibility of superplastically forming 7475-T6 aluminum sheet into a corrugated wall configuration and to demonstrate the structural integrity of the construction by testing. The corrugated configuration selected has beaded web segments separating curved-cap segments. Eight test specimens were fabricated. Two specimens were simply a single sheet of aluminum superplastically formed to a beaded-web, curved-cap corrugation configuration. Six specimens were single-sheet corrugations modified by adhesive bonding additional sheet material to selectively reinforce the curved-cap portion of the corrugation. The specimens were tested to failure by crippling in end compression at room temperature.

Davis, Randall C.; Royster, Dick M.; Bales, Thomas T.; James, William F.; Shinn, Joseph M., Jr.

1991-01-01

190

Hydrogen sulfide removal from sediment and water in box culverts/storm drains by iron-based granules.  

PubMed

A renewable granular iron-based technology for hydrogen sulfide removal from sediment and water in box culverts and storm drains is discussed. Iron granules, including granular ferric hydroxide (GFH), granular ferric oxide (GFO) and rusted waste iron crusts (RWIC) embedded in the sediment phase removed aqueous hydrogen sulfide formed from sedimentary biological sulfate reduction. The exhausted iron granules were exposed to dissolved oxygen and this regeneration process recovered the sulfide removal capacities of the granules. The recovery is likely attributable to the oxidation of the ferrous iron precipitates film and the formation of new reactive ferric iron surface sites on the iron granules and sand particles. GFH and RWIC showed larger sulfide removal capacities in the sediment phase than GFO, likely due to the less ordered crystal structures on their surfaces. This study demonstrates that the iron granules are able to remove hydrogen sulfide from sediment and water in box culverts and storm drains and they have the potential to be regenerated and reused by contacting with dissolved oxygen. PMID:24355850

Sun, J L; Shang, C; Kikkert, G A

2013-01-01

191

Bag Pipe  

NSDL National Science Digital Library

In this activity, learners explore sound by constructing their very own bagpipe instrument. Learners use PVC pipe, a ziploc bag, rubber tubing, rubber bands, a plastic bottle, and a rubber glove to build their bagpipe. Note: a drill is required, but is not included in the cost of materials.

Workshop, Environmental S.

2011-01-01

192

Experimental studies of magnetically scannable leaky-wave antennas having a corrugated ferrite slab\\/dielectric layer structure  

Microsoft Academic Search

The radiation characteristics of a magnetically scannable leaky-wave antenna using a corrugated ferrite slab supported by a Teflon waveguide have been demonstrated experimentally. A corrugated polycrystalline yttrium iron garnet (YIG) slab having the dimensions 150.0 mm x 15.0 mm x 10 mm has been fabricated. The corrugation depth, corrugation spacing, and number of corrugations are 150.0 microns, 2.0 mm, and

Heshmatollah Maheri; Makoto Tsutsumi; Nobuaki Kumagai

1988-01-01

193

Flood magnitude and frequency of Jacks Run at the culvert on U.S. Route 206, Southampton Township, Burlington County, New Jersey  

USGS Publications Warehouse

Flood magnitude and frequency of Jacks Run at the culvert on U.S. Route 206, Southampton Township, New Jersey, were determined by using the rational method. Flood magnitude and frequency estimates, as well as basin characteristics, are included in this report. The 100-year-flood estimate is 29 cubic feet per second.

Barringer, Thomas

1996-01-01

194

Progress Toward Corrugated Feed Horn Arrays in Silicon  

SciTech Connect

We are developing monolithic arrays of corrugated feed horns fabricated in silicon for dual-polarization single-mode operation at 90, 145 and 220 GHz. The arrays consist of hundreds of platelet feed horns assembled from gold-coated stacks of micro-machined silicon wafers. As a first step, Au-coated Si waveguides with a circular, corrugated cross section were fabricated; their attenuation was measured to be less than 0.15 dB/cm from 80 to 110 GHz at room temperature. To ease the manufacture of horn arrays, electrolytic deposition of Au on degenerate Si without a metal seed layer was demonstrated. An apparatus for measuring the radiation pattern, optical efficiency, and spectral band-pass of prototype horns is described. Feed horn arrays made of silicon may find use in measurements of the polarization anisotropy of the cosmic microwave background radiation.

Britton, J.; Yoon, K. W.; Beall, J. A.; Becker, D.; Cho, H. M.; Hilton, G. C.; Niemack, M. D.; Irwin, K. D. [Quantum Sensors Group, NIST, Boulder, CO 80305 (United States)

2009-12-16

195

Helically Corrugated Waveguides for Compression of Frequency Swept Pulses  

Microsoft Academic Search

Waveguides with a helical corrugation on the inner surface have proven an effective dispersive medium for the compression of smoothly frequency modulated microwave pulses. This paper presents the results of experiments where ~5.7 kW, X-band (8.0 GHz - 12.5 GHz), microwave pulses of 67 ns duration and 5% frequency modulation were compressed into 2.8 ns pulses with 12 times higher

P. Macinnes; K. Ronald; A. W. Cross; A. D. R. Phelps; A. R. Young; W. He; G. Burt; C. G. Whyte; S. V. Samsonov; V. L. Bratman; G. G. Denisov

2006-01-01

196

Experimental results on microwave pulse compression using helically corrugated waveguide  

Microsoft Academic Search

The paper presents new results on the development of a method to generate ultrahigh-power short-microwave pulses by using a known principle of compression (reduction in pulse duration accompanying with increase in pulse amplitude) of a frequency-swept wave packet propagating through a dispersive medium. An oversized circular waveguide with helical-corrugations of its inner surface ensures an eigenwave with strongly frequency dependent

M. McStravick; S. V. Samsonov; K. Ronald; S. V. Mishakin; W. He; G. G. Denisov; C. G. Whyte; V. L. Bratman; A. W. Cross; A. R. Young; P. Macinnes; C. W. Robertson; A. D. R. Phelps

2010-01-01

197

Corrugated Rectangular Waveguide Tunable Backward Wave Oscillator for Terahertz Applications  

Microsoft Academic Search

A tunable backward wave oscillator (BWO) for terahertz applications is proposed. The use of a corrugated rectangular waveguide as the slow-wave structure permits relevant performance together with full compatibility with microfabrication technologies. The design, done using an analytical electromagnetic model, is fully verified by 3-D particle-in-cell simulations. A 20% tuning bandwidth is obtained at a central frequency of 1 THz,

Mauro Mineo; Claudio Paoloni

2010-01-01

198

Bose–Einstein condensate flow in a corrugated magnetic waveguide  

Microsoft Academic Search

The flow of a Bose–Einstein condensate through smooth and corrugated waveguides is studied by direct numerical solution of the time-dependent Gross–Pitaevskii equation. One end of each waveguide has a teacup longitudinal potential, which when lowered generates a quasi-continuous supersonic flow. As the nonlinear strength factor, which is proportional to the scattering length times the number of atoms, becomes more positive,

M C Witthoeft; M S Pindzola

2006-01-01

199

Optimization of the leading edge segment of a corrugated wing  

NASA Astrophysics Data System (ADS)

Insect wings consist of flat plates of membranes stiffened by spars. The effect of this structure is that the wings appear as corrugated surfaces when considered on chordwise sections. We know that aerodynamically efficient insects such as a dragonfly engage in fixed wing flight modes for extended periods. The analysis in the literature has shown that the aerodynamic efficiency (cl/cd) of a corrugated aerofoil is sensitive to Reynolds number (Re) and angle-of-attack (AoA), yet the conclusions established are on the basis of flow analysis on a single baseline shape only. The sample size of the aerofoils must be extended further so that the influence and merits of corrugated shape features can be established. In this work, a design-of-experiments (DoE) approach is applied to induce systematic shape perturbations on a select, off-the-shelf baseline shape one feature at a time over a set number of increments. At each shape increment, the aerodynamic forces are established using a high fidelity CFD solver. The design space is modeled at a Re of 20,000 and 34,000 and at flow angle of 4.0° to represent a Micro Air Vehicle (MAV) in glide. The results confirmed the importance of the leading and trailing edge deflections on cl/cd. At Re = 20, 000, cl/cd of a corrugated aerofoil with deflection at the leading edge region only is 16% higher than the baseline shape, and 39% higher than the flat plate. At Re = 34, 000, cl/cd performance is sensitive to the trailing edge deflection. At the optimum deflection setting, cl/cd is 18% higher than the baseline shape and 23% higher than the flat plate. The results confirm that the leading and trailing edge deflections are critical to cl/cd for a MAV in glide.

Khurana, Manas; Chahl, Javaan

2014-03-01

200

Cooling performance of heat sinks with corrugated-fins  

Microsoft Academic Search

Heat sinks with corrugated fins have been developed for effective cooling of large-scale integrated circuit (LSI) packages. These heat sinks are so light that they are suitable for cooling small and light LSI packages with low\\/high heat generation, e.g. quad flat package (QFP), ball grid array (BGA) package, chip scale package (CSP), etc., which are contributing to the downsizing of

Masahito Tasaka; Kenjiro Shinohara; Chihiro Hayashi; Shoichi Kashima; Ken Koyama

1998-01-01

201

Rectangular-waveguide-excited short backfire antenna with corrugated rim  

Microsoft Academic Search

The letter presents experimental results at X-band for a short backfire antenna with corrugated rim, which is excited by a rectangular waveguide. It is shown that the use of the waveguide feed can lead to a compact antenna having a directive gain of 20 dB, sidelobe levels of -17 dB and vswr in the range 1.1-2.

M. S. Leong; P. S. Kooi

1979-01-01

202

Corrugated outer sheath gas-insulated transmission line  

DOEpatents

A gas-insulated transmission line includes two transmission line sections each of which are formed of a corrugated outer housing enclosing an inner high-voltage conductor disposed therein, with insulating support means supporting the inner conductor within the outer housing and an insulating gas providing electrical insulation therebetween. The outer housings in each section have smooth end sections at the longitudinal ends thereof which are joined together by joining means which provide for a sealing fixed joint.

Kemeny, George A. (Pittsburgh, PA); Cookson, Alan H. (Churchill Boro, PA)

1981-01-01

203

Thermally Tuning Terahertz Surface Plasmon Polaritons in Corrugated Semiconductor Films  

Microsoft Academic Search

In this work, we show that surface plasmon polaritons (SPPs) at terahertz (THz) frequencies can be tuned by changing the temperature in a periodically corrugated thin film of indium antimonide (InSb) sandwiched between air and dielectric. When a THz electromagnetic wave illuminates the structure, the temperature-dependent THz SPPs can be excited, and the first and second-order modes and their cross-couplings

Xin Wu; Ruwen Peng; De Li; Ruili Zhang; Renhao Fan; Claudio Ferrari; Mu Wang

2009-01-01

204

Surveying drainage culvert use by carnivores: sampling design and cost-benefit analyzes of track-pads vs. video-surveillance methods.  

PubMed

Environmental assessment studies often evaluate the effectiveness of drainage culverts as habitat linkages for species, however, the efficiency of the sampling designs and the survey methods are not known. Our main goal was to estimate the most cost-effective monitoring method for sampling carnivore culvert using track-pads and video-surveillance. We estimated the most efficient (lower costs and high detection success) interval between visits (days) when using track-pads and also determined the advantages of using each method. In 2006, we selected two highways in southern Portugal and sampled 15 culverts over two 10-day sampling periods (spring and summer). Using the track-pad method, 90% of the animal tracks were detected using a 2-day interval between visits. We recorded a higher number of crossings for most species using video-surveillance (n = 129) when compared with the track-pad technique (n = 102); however, the detection ability using the video-surveillance method varied with type of structure and species. More crossings were detected in circular culverts (1 m and 1.5 m diameter) than in box culverts (2 m to 4 m width), likely because video cameras had a reduced vision coverage area. On the other hand, carnivore species with small feet such as the common genet Genetta genetta were detected less often using the track-pad surveying method. The cost-benefit analyzes shows that the track-pad technique is the most appropriate technique, but video-surveillance allows year-round surveys as well as the behavior response analyzes of species using crossing structures. PMID:21181260

Mateus, Ana Rita A; Grilo, Clara; Santos-Reis, Margarida

2011-10-01

205

Heat pipe technology  

NASA Technical Reports Server (NTRS)

A bibliography of heat pipe technology to provide a summary of research projects conducted on heat pipes is presented. The subjects duscussed are: (1) heat pipe applications, (2) heat pipe theory, (3) design and fabrication, (4) testing and operation, (5) subject and author index, and (6) heat pipe related patents.

1972-01-01

206

Spectral gap induced by structural corrugation in armchair graphene nanoribbons  

NASA Astrophysics Data System (ADS)

We study the effects of the structural corrugation or rippling on the electronic properties of undoped armchair graphene nanoribbons (AGNRs). First, reanalyzing the single corrugated graphene layer we find that the two inequivalent Dirac points (DPs) move away from each other. Futhermore, the Fermi velocity vF decreases when the rippling increases. Regarding the AGNRs, whose metallic behavior depends on their widths, we analyze, in particular, the case of the zero-gap band-structure AGNRs. By solving the Dirac equation with adequate boundary conditions we show that, due to the shifting of the DP, a gap opens up in the spectra. This gap scales with the square of the rate between the height and the wavelength of the deformation. We confirm this prediction by an exact numerical solution of the finite width rippled AGNR. Moreover, we find that the quantum conductance, calculated by the nonequilibrium Green’s function technique, vanishes when the gap opens up. The main conclusion of our results is that a conductance gap should appear for all undoped corrugated AGNR, independently of their widths.

Costamagna, S.; Hernandez, O.; Dobry, A.

2010-03-01

207

Interaction of streamers and stationary corrugated ionization waves in semiconductors  

NASA Astrophysics Data System (ADS)

A numerical simulation of evolution of an identical interacting streamers array in semiconductors has been performed using the diffusion-drift approximation and taking into account the impact and tunnel ionization. It has been assumed that the external electric field E0 is static and uniform, the background electrons and holes are absent, the initial avalanches start simultaneously from the nodes of the plane hexagonal lattice, which is perpendicular to the external field, but the avalanches and streamers are axially symmetric within a cylinder of radius R. It has been shown that under certain conditions, the interaction between the streamers leads finally either to the formation of two types of stationary ionization waves with corrugated front or to a stationary plane ionization wave. A diagram of different steady states of this type of waves in the plane of parameter E0,R has been presented, and a qualitative explanation of the plane partition into four different regions has been given. Characteristics of corrugated waves have been studied in detail and discussed in the region of R and E0 large values, in which the maximum field strength at the front is large enough for the tunnel ionization implementation. It has been shown that corrugated waves ionize semiconductors more efficiently than flat ones, especially in relatively weak external fields.

Kyuregyan, A. S.

2014-04-01

208

Interaction of streamers and stationary corrugated ionization waves in semiconductors.  

PubMed

A numerical simulation of evolution of an identical interacting streamers array in semiconductors has been performed using the diffusion-drift approximation and taking into account the impact and tunnel ionization. It has been assumed that the external electric field E0 is static and uniform, the background electrons and holes are absent, the initial avalanches start simultaneously from the nodes of the plane hexagonal lattice, which is perpendicular to the external field, but the avalanches and streamers are axially symmetric within a cylinder of radius R. It has been shown that under certain conditions, the interaction between the streamers leads finally either to the formation of two types of stationary ionization waves with corrugated front or to a stationary plane ionization wave. A diagram of different steady states of this type of waves in the plane of parameter E0,R has been presented, and a qualitative explanation of the plane partition into four different regions has been given. Characteristics of corrugated waves have been studied in detail and discussed in the region of R and E0 large values, in which the maximum field strength at the front is large enough for the tunnel ionization implementation. It has been shown that corrugated waves ionize semiconductors more efficiently than flat ones, especially in relatively weak external fields. PMID:24827322

Kyuregyan, A S

2014-04-01

209

Measuring the electronic corrugation at the metal/organic interface  

NASA Astrophysics Data System (ADS)

Angle-resolved two-photon photoemission is used to probe the image potential states on monolayers of metal-free phthalocyanine (H2Pc) and cobalt phthalocyanine (CoPc) on the Ag(100) and Ag(111) surfaces. We find that in the plane of the surface the normally flat potential landscape becomes significantly corrugated in the presence of the phthalocyanine lattice, causing the opening of a band gap in the first image potential state, in agreement with previous findings. Interestingly, the data show that the absence of the electron dense metal center does not qualitatively alter this picture. Experiments conducted on Ag(100) and Ag(111) crystals demonstrate that the surface band structure and symmetry of the metal surface plays a minor role in the band folding phenomenon. A two-dimensional model that takes into account both the band structure of the substrate and the corrugation of the potential landscape in the surface plane due to the molecular lattice is presented and compared to experiment. This model enables the observation that, counter to intuition, the Co metal center at the CoPc/Ag interface actually smooths the interfacial potential relative to that of the H2Pc/Ag interface. We suggest that the strong corrugation of the potential at the organic/metal interface measured herein may account for the recent observation of surface umklapp scattering in recent ultraviolet photoemission experiments on organic/metal interfaces.

Caplins, Benjamin W.; Shearer, Alex J.; Suich, David E.; Muller, Eric A.; Harris, Charles B.

2014-04-01

210

PROCESSING OF NANOSTRUCTURED COPPER BY REPETITIVE CORRUGATION AND STRAIGHTENING (RCS)  

SciTech Connect

A new process, Repetitive Corrugation and Straightening (RCS), has been developed to create bulk, nanostructured copper. In this investigation, a high purity (99.99%). copper bar measuring 6 x 6 x 50 mm with an average grain size of 765 {micro}m was used as the starting material. It was repetitively corrugated and straightened for 14 times with 90{degree} rotations along its longitudinal axis between consecutive corrugation-straightening cycles. The copper was cooled to below room temperature before each RCS cycle. The grain size obtained after the RCS process was in the range of twenty to a few hundred nanometers, and microhardness was increased by 100%. Both equilibrium and non-equilibrium grain boundaries are observed. This work demonstrates the capability of the RCS process in refining grain size of metal materials. The RCS process can be easily adapted to large-scale industrial production and has the potential to pave the way to large-scale structural applications of nanostructured materials.

Zhu, Y.T.; Jiang, H. [and others

2000-10-01

211

Transient coexisting nanophases in ultrathin films confined between corrugated walls  

SciTech Connect

Grand-canonical Monte Carlo and microcanonical molecular dynamics methods have been used to simulate an ultrathin monatomic film confined to a slit-pore [i.e., between solid surfaces (walls)]. Both walls comprise atoms rigidly fixed in the face centered cubic (100) configuration; one wall is smooth on a nanoscale and the other is corrugated (i.e., scored with regularly spaced rectilinear grooves one to several nanometers wide). Properties of the film have been computed as a function of the lateral alignment (registry), with the temperature, chemical potential, and distance between the walls kept constant. Changing the registry carries the film through a succession of equilibrium states, ranging from all solid at one extreme to all fluid at the other. Over a range of intermediate registries the film consists of fluid and solid portions in equilibrium, that is fluid-filled nanocapillaries separated by solid strips. The range of registries over which such fluid--solid equilibria exist depends upon the width of the grooves and the frequency of the corrugation. For grooves of width comparable to the range of the interatomic potential, fluid and solid phases cease to coexist. In the limit of very wide grooves the character of the film is similar to that of the film confined by strictly smooth walls. The rich phase behavior of the confined film due to the coupling between molecular (registry) and nano (corrugation) scales has obvious implications for boundary lubrication.

Curry, J.E.; Zhang, F.; Cushman, J.H. (Lilly Hall of Life Sciences, Purdue University, West Lafayette, Indiana 47907 (United States)); Schoen, M. (Institut fuer Theoretische Physik, Technische Universitaet Berlin, Hardenbergstr. 36, 10623 Berlin (Germany)); Diestler, D.J. (Department of Agronomy, Keim Hall, University of Nebraska-Lincoln, Lincoln, Nebraska 68583-0915 (United States))

1994-12-15

212

Assessment of scour-critical data collected at selected bridges and culverts in South Carolina, 1990-92  

USGS Publications Warehouse

Data at bridges and culverts were collected at 3,506 stream crossings in South Carolina during 1990-92. The data include general information unique to the structure; structural data; and hydraulic, geomorphic, and vegetation information. The data are stored in the U.S. Geological Survey South Carolina District Bridge-Scour Data Base. Observed- and potential-scour indexes were computed from the applicable data variables. Sites with observed-scour indexes exceeding ten and (or) potential-scour indexes exceeding 20 are considered to have significant scour-related problems. Of the 3,506 sites inspected, 257 sites had an observed-scour index exceeding ten, 214 sites had a potential-scour index exceeding 20, and 85 sites had observed- and potential-scour indexes exceeding both threshold values.

Hurley, N. M., Jr.

1996-01-01

213

Experimental investigation of the strength of multiweb beams with corrugated webs  

NASA Technical Reports Server (NTRS)

The results of an experimental investigation of the strength of multiweb beams with corrugated webs are reported. Included in the investigation were two types of connection between the web and the skin. A comparison between the structural efficiency of corrugated-web and channel-web multiweb beams is presented, and it is shown that, for a considerable range of the structural index, corrugated-web beams can be built which are structurally more efficient than channel-web beams.

Fraser, Allister F

1956-01-01

214

Geometrical investigations of the Casimir effect: Thickness and corrugation dependencies  

NASA Astrophysics Data System (ADS)

In the quantum theory the vacuum is not empty space. It is considered as a state of infinite energy arising due to zero point fluctuations of the vacuum. Calculation of any physically relevant process requires subtracting this infinite energy using a procedure called normalization. As such the vacuum energy is treated as an infinite constant. However, it has been established beyond doubt that mere subtraction of this infinite constant does not remove the effect of vacuum fluctuations and it cannot be treated just as a mathematical artifact. The presence of boundaries, which restricts the vacuum field, causes vacuum polarization. Any non-trivial space-time topology can cause similar effects. This is manifested as the Casimir effect, whereby the boundaries experience a force due to a change in the energy of the vacuum. To calculate the vacuum energy we treat the boundaries or other restrictive conditions as classical backgrounds, which impose boundary conditions on the solution of the vacuum field equations. Alternatively, we can incorporate the classical background in the Lagrangian of the system as classical potentials, which automatically include the boundary conditions in the field equations. Any change in the boundary conditions changes the vacuum energy and consequently the Casimir force is experienced by the boundaries. In this dissertation we study the geometric aspect of the Casimir effect. We consider both the scalar field and the physically relevant electromagnetic field. After a brief survey of the field in Chapter 1, we derive the energy expression using the Schwinger's quantum action principle in Chapter 2. We present the multiple scattering formalism for calculating the vacuum energy, which allows us to calculate the interaction energy between disjoint bodies and subtract out the divergent terms from the beginning. We then solve the Green's dyadic equation for the electromagnetic field interacting with the planar background surfaces, where we can decompose the problem into two transverse scalar modes. In Chapter 3 we collect all the solutions for the scalar Green's functions for the planar and the cylindrical geometries, which are relevant for this dissertation. In Chapter 4 we derive the interaction energy between two dielectric slabs of finite thickness. Taking the thickness of the slabs to infinity leads to the Lifshitz results for the two infinite dielectric semi-spaces, while taking the dielectric permittivity to infinity gives the well-known Casimir energy between two perfect conductors. We then present a simple model to consider the thin-plate limit (taking the thickness of the slabs to zero) based on Drude-Sommerfeld free electron gas model, which modifies the plasma frequency of the material to include the finite size dependence. We get a non-vanishing result for the Lifshitz energy in the slab thickness going to zero limit. This is remarkable progress as it allows us to understand the infinitesimal thickness limit and opens a possibility of extending this model to apply it to graphene and other two dimensional surfaces. The Casimir and Casimir-Polder results in the perfect conductor limit give us the expected results. In Chapter 5 we study the lateral Casimir torque between two concentric corrugated cylinders described by delta-potentials, which interact through a scalar field. We derive analytic expressions for the Casimir torque for the case when the corrugation amplitudes are small in comparison to the corrugation wavelengths. We derive explicit results for the Dirichlet case, and exact results for the weak coupling limit, in the leading order. The results for the corrugated cylinders approach the corresponding expressions for the case of corrugated parallel plates in the limit of large radii of the cylinders (relative to the difference in their radii) while keeping the corrugation wavelength fixed. In Chapter 6 we calculate the lateral Casimir energy between corrugated parallel dielectric slabs of finite thickness using the multiple scattering formalism in the perturbative approximation and obt

Parashar, Prachi

215

Numerical exploration of the origin of aerodynamic enhancements in [low-Reynolds number] corrugated airfoils  

NASA Astrophysics Data System (ADS)

This paper explores the flow structure of a corrugated airfoil using a high-fidelity implicit large eddy simulation approach. The first three-dimensional simulations for a corrugated wing section are presented considering a range of Reynolds numbers of Rec = 5 × 103 to 5.8 × 104 bridging the gap left by previous numerical and experimental studies. Several important effects are shown to result from the corrugations in the leading-edge region. First, interaction between the detached shear layer and the first corrugation peak promotes recirculation upstream and enhances transition to turbulence due to flow instabilities. Thus, early transitional flow develops on the corrugated wing which helps to delay stall even at Reynolds numbers as low as Rec = 1 × 104. Transition is shown to occur as early as Rec = 7.5 × 103 and quickly advances toward the leading-edge as Reynolds number is increased. Modification of the first corrugation peak height produces significantly reduced separation and improved aerodynamic forces demonstrating the sensitivity of flow behavior to leading-edge geometry. Second, the unusual orientation of the corrugated surface and strong suction resulting from rapidly turning fluid over the separated region upstream of the first corrugation produces a new effect which serves to reduce drag. This effect was amplified through the enhanced interaction produced by a modified geometry. Corrugations were found to be most advantageous in the leading-edge region and could be optimized to properly take advantage of the flow field under different operating conditions.

Barnes, Caleb J.; Visbal, Miguel R.

2013-11-01

216

Design and performance of corrugated waveguide structures based on slab waveguide principles  

NASA Astrophysics Data System (ADS)

A simple design is developed for corrugated waveguides for operation in the millimeterwave range of frequencies. The method determines both the corrugation period and the depth. The design is based on slab waveguide principles and uses solutions of the (scalar) boundary value problem of the slab waveguide to determine the corrugation depth and the corrugation spacing. The design tecimique compares well with other techniques developed for the purpose. Reflections at 90 at certain specific wavelengths are measured in the far field to obtain the radiation patterns. The patterns show good agreement with theoretical predictions confirming the effectiveness of design principles used. Measurements range in the frequencies from 90 GHz to 100 GHz. 1.

Ayekavadi, Raj; Yeh, C. S.; Butler, Jerome K.; Evans, Gary A.; Stabile, Paul J.; Rosen, A.

1992-12-01

217

Pipe-to-Pipe Impact Tests.  

National Technical Information Service (NTIS)

The objective of the program is to generate experimental data to evaluate the Nuclear Regulatory Commission's requirements for predicting impact damage. These state that upon impact between two pipes it shall be assumed that the moving pipe will: rupture ...

M. C. C. Bampton J. M. Alzheimer F. A. Simonen

1982-01-01

218

Dispersion of helically corrugated waveguides: analytical, numerical, and experimental study.  

PubMed

Helically corrugated waveguides have recently been studied for use in various applications such as interaction regions in gyrotron traveling-wave tubes and gyrotron backward-wave oscillators and as a dispersive medium for passive microwave pulse compression. The paper presents a summary of various methods that can be used for analysis of the wave dispersion of such waveguides. The results obtained from an analytical approach, simulations with the three-dimensional numerical code MAGIC, and cold microwave measurements are analyzed and compared. PMID:15600525

Burt, G; Samsonov, S V; Ronald, K; Denisov, G G; Young, A R; Bratman, V L; Phelps, A D R; Cross, A W; Konoplev, I V; He, W; Thomson, J; Whyte, C G

2004-10-01

219

Direct synthesis of corrugated superlattices on non-(100)-oriented surfaces  

NASA Astrophysics Data System (ADS)

The paper reports on the direct synthesis of superlattices with lateral corrugation of the interfaces on (211), (311), and (111) GaAs substrates by molecular-beam epitaxy. Reflection electron diffraction directly shows the formation of arrays of macrosteps during epitaxial growth. High-resolution transmission electron microscopy confirms the transfer of the surface structure to the GaAs/AlAs interface which results in distinct energy shifts in the luminescence of GaAs/AlAs multilayer structures. The surface structure gives rise to lateral quantum-size effects which result in increased exciton continuum energies, in strong exciton-phonon interaction, and in pronounced optical anisotropy.

Noetzel, R.; Ledentsov, N. N.; Daeweritz, L.; Hohenstein, M.; Ploog, K.

1991-12-01

220

The Sacred Calf Pipe.  

ERIC Educational Resources Information Center

Tells how the author learned of and recorded the list of Sioux tribe members who have kept the White Buffalo Calf Pipe. Reviews the legend surrounding the origin of the pipe and describes the succession of pipe-keepers and how they inherit the pipe. (Author/AEM)

Simms, Thomas E.

1987-01-01

221

Shield For Flexible Pipe  

NASA Technical Reports Server (NTRS)

Cylindrical shield designed to fit around flexible pipe to protect nearby workers from injury and equipment from damage if pipe ruptures. Designed as pressure-relief device. Absorbs impact of debris ejected radially from broken flexible pipe. Also redirects flow of pressurized fluid escaping from broken pipe onto flow path allowing for relief of pressure while minimizing potential for harm.

Ponton, Michael K.; Williford, Clifford B.; Lagen, Nicholas T.

1995-01-01

222

Cross-Polarization Cancellation in an Offset Parabolic Reflector Antenna Using a Corrugated Matched Feed  

Microsoft Academic Search

This letter presents the design of a dual-mode corrugated matched feed to cancel the unwanted high cross polarization and beam squinting in an offset parabolic reflector antenna. The matched feed concept has been implemented in a cylindrical corrugated structure by adding a higher order HE21 mode to the fundamental HE11 mode. The designed feed was then used to illuminate a

S. B. Sharma; Dhaval Pujara; S. B. Chakrabarty; Ranajit Dey

2009-01-01

223

Fatigue Resistance of Large-Size Helically Corrugated Aluminum Sheathed Cables  

Microsoft Academic Search

Large-size corrugated aluminum sheathed cables are finding an increasing use in duct and manhole installations. The complex sheath geometry, relatively large conductors and increased insulation thickness, combined with restricted manholes, would lead to severe sheath strains, increasing the probability of sheath fatigue failure. The results of a program is presented for evaluating fatigue life of large-sized corrugated aluminum sheathed cables.

S. Krishnasamy

1980-01-01

224

Convective heat transfer to temperature dependent property fluids in the entry region of corrugated tubes  

Microsoft Academic Search

The present experimental investigation is aimed to the analysis of the thermal performances of corrugated wall tubes employed in a broad variety of industrial applications in order to intensify the convective heat transfer. Both axial symmetrical and helical corrugations with different pitch values, have been considered in the present analysis. In particular, the phenomena arising due both to the wall

S Rainieri; G Pagliarini

2002-01-01

225

Effect of Corrugated Flute Shape on Fibreboard Edgewise Crush Strength and Bending Stiffness  

Microsoft Academic Search

The influence of corrugated fibreboard fluting geometry on strength and stiffness is modelled and a method to optimize flute profile is presented. The fluted medium in a corrugated fibreboard is modelled as a connection of curved arc and straight flank segments. Flute pitch, flute height, flank length, arc radius and angle of wrap are normalized to form a set of

T. J. URBANIK

226

Manipulation of Thought Content as a Determinant of Mood and Corrugator Electromyographic Activity in Depressed Patients  

ERIC Educational Resources Information Center

Examines the effects of unhappy thoughts on mood and corrugator EMG (electromyographic activity) in depressed patients. Its purpose was to obtain evidence relevant to cognitive models of depression and to examine the usefulness of corrugator EMG as an indicator of depressed mood. (Author/RK)

Teasdale, John D.; Bancroft, Judy

1977-01-01

227

Spatial cost efficiency in waste paper handling: the case of corrugated board in Sweden  

Microsoft Academic Search

This paper analyzes the spatial cost efficiency of the Swedish legislation regarding waste disposal handling. We focus on the case of corrugated board and recognize that the different counties in Sweden possess different economic prerequisites in terms of waste paper recovery and utilization potential. We employ data for six corrugated board mills and 20 counties and a non-linear programming model

Christer Berglund

2004-01-01

228

Shear-driven and channel flow of a liquid film over a corrugated or indented wall  

Microsoft Academic Search

The shape of the interface between two superimposed layers in a two-dimensional channel confined between a planar and a corrugated or indented wall is investigated in the limit of Stokes flow. A perturbation analysis for walls with small-amplitude sinusoidal corrugations reveals that an insoluble surfactant amplifies the deformation of the interface and causes a negative drift in the phase shift

H. Luo; C. Pozrikidis

2006-01-01

229

Quasi-static axial and lateral crushing of radial corrugated composite tubes  

Microsoft Academic Search

This paper presents the effect of corrugation geometry on the crushing behavior, energy absorption, failure mechanism, and failure mode of woven roving glass fibre\\/epoxy laminated composite tube. Experimental investigations were carried out on three geometrical different types of composite tubes subjected to axial and lateral compressive loadings. On the addition to a radial corrugated composite tube, cylindrical composite tube, and

Elfetori F. Abdewi; Shamsuddeen Sulaiman; A. M. S. Hamouda; E. Mahdi

2008-01-01

230

The effects of cell face curvature and corrugations on the stiffness and strength of metallic foams  

Microsoft Academic Search

The measured mechanical properties of conventional lightweight metallic foams fall far short of those predicted by idealized models for closed cell foams. Their poor mechanical performance can be attributed, to a large extent, to curved and corrugated cell faces present within the foams. Idealized honeycombs and foams with idealized cell structure and curved or corrugated cell edges and faces are

A. E. Simone; L. J. Gibson

1998-01-01

231

A design chart for the plastic collapse of corrugated cylinders under external pressure  

Microsoft Academic Search

The paper presents a theoretical and an experimental investigation into the plastic collapse of circular steel corrugated cylinders under external hydrostatic pressure. The experimental investigation gives a detailed study of 9 steel corrugated cylinders which were tested to destruction. Six of these cylinders failed by plastic non-symmetric bifurcation buckling and three failed by plastic axisymmetric deformation. The results of these

C. T. F. Ross; A. Terry; A. P. F. Little

2001-01-01

232

Flood magnitude and frequency of Little Timber Creek at the culvert on Interstate Route 295, Haddon Heights Township, Camden County, New Jersey  

USGS Publications Warehouse

The magnitude and frequency of floods at the Little Timber Creek at the culvert on Interstate 295, at milepost 28.9, in Haddon Heights Township, New Jersey, were determined by using the New Jersey Department of Environmental Protection Special Report 38 method. Flood-magnitude and -frequency estimates, as well as drainage-basin characteristics, are included in this report. The 100-year-flood estimate is 770 cubic feet per second.

Barringer, T. H.

1996-01-01

233

Experimental Demonstration of Mode Change in a Q-Band Oversized Backward Wave Oscillator due to Corrugation Number  

Microsoft Academic Search

Operation mode of an oversized backward wave oscillator is studied experimentally, using an oversized slow-wave structure. The dispersion characteristics of the slow-wave structure are determined by the average radius, corrugation amplitude and pitch length of the periodic waveguide. The corrugation amplitude and the corrugation period mainly determine the upper cutoff frequency of the lowest mode. The lower cutoff frequency is

Kazuo Ogura; Ryo Yoshida; Kiyofumi Komiyama; Masakazu Sakai; Hoshiyuki Yamazaki

2004-01-01

234

Directional terahertz emission from corrugated InAs structures.  

PubMed

The terahertz (THz) radiation from transient dipoles, formed by distinct diffusion coefficients between oppositely charged carriers as often observed in low band gap semiconductors, propagates with an anisotropic amplitude distribution perpendicular to the dipole axis along the diffusive motion. By directionally adjusting the electronic diffusion, we conceptualize groove-patterned THz emitters based on (100) InAs thin films and demonstrate the unidirectional radiation. Line-of-sight emission along the surface-normal direction is greatly enhanced in a distributed asymmetric trapezoid with its period similar to the electronic diffusion length of InAs. This directional enhancement is in clear contrast to the constant emission amplitude along the lateral direction, regardless of pattern scale, which manifests the role of groove patterns as microscale reflectors in laterally corrugating the carrier density. In contrast to the rather limited nonlinearity in (100) plane, the azimuthal angle dependence of the THz field amplitude in corrugated samples shows a combined effect of diffusive transport and second-order nonlinearity, whose compositional contributions varies in different structures. PMID:24105518

Yim, Jong-Hyuk; Jeong, Hoonil; Irfan, Muhammad; Lee, Eun-Hye; Song, Jin-Dong; Jho, Young-Dahl

2013-08-26

235

Imaging Local Electronic Corrugations and Doped Regions in Graphene  

SciTech Connect

Electronic structure heterogeneities are ubiquitous in two-dimensional graphene and profoundly impact the transport properties of this material. Here we show the mapping of discrete electronic domains within a single graphene sheet using scanning transmission X-ray microscopy in conjunction with ab initio density functional theory calculations. Scanning transmission X-ray microscopy imaging provides a wealth of detail regarding the extent to which the unoccupied levels of graphene are modified by corrugation, doping and adventitious impurities, as a result of synthesis and processing. Local electronic corrugations, visualized as distortions of the {pi}*cloud, have been imaged alongside inhomogeneously doped regions characterized by distinctive spectral signatures of altered unoccupied density of states. The combination of density functional theory calculations, scanning transmission X-ray microscopy imaging, and in situ near-edge X-ray absorption fine structure spectroscopy experiments also provide resolution of a longstanding debate in the literature regarding the spectral assignments of pre-edge and interlayer states.

B Schultz; C Patridge; V Lee; C Jaye; P Lysaght; C Smith; J Barnett; D Fischer; D Prendergast; S Banerjee

2011-12-31

236

A comprehensive track model for the improvement of corrugation models  

NASA Astrophysics Data System (ADS)

This paper presents a detailed model of the railway track based on wave propagation, suitable for corrugation studies. The model analyses both the vertical and the transverse dynamics of the track. Using the finite strip method (FSM), only the cross-section of the rail must be meshed, and thus it is not necessary to discretise a whole span in 3D. This model takes into account the discrete nature of the support, introducing concepts pertaining to the theory of periodic structures in the formulation. Wave superposition is enriched taking into account the contribution of residual vectors. In this way, the model obtains accurate results when a finite section of railway track is considered. Results for the infinite track have been compared against those presented by Gry and Müller. Aside from the improvements provided by the model presented in this paper, which Gry's and Müller's models do not contemplate, the results arising from the comparison prove satisfactory. Finally, the calculated receptances are compared against the experimental values obtained by the authors, demonstrating a fair degree of adequacy. Finally, these receptances are used within a linear model of corrugation developed by the authors.

Gómez, J.; Vadillo, E. G.; Santamaría, J.

2006-06-01

237

Insulated pipe clamp design  

SciTech Connect

Thin wall large diameter piping for breeder reactor plants can be subjected to significant thermal shocks during reactor scrams and other upset events. On the Fast Flux Test Facility, the addition of thick clamps directly on the piping was undesired because the differential metal temperatures between the pipe wall and the clamp could have significantly reduced the pipe thermal fatigue life cycle capabilities. Accordingly, an insulated pipe clamp design concept was developed. The design considerations and methods along with the development tests are presented. Special considerations to guard against adverse cracking of the insulation material, to maintain the clamp-pipe stiffness desired during a seismic event, to minimize clamp restraint on the pipe during normal pipe heatup, and to resist clamp rotation or spinning on the pipe are emphasized.

Anderson, M.J.; Hyde, L.L.; Wagner, S.E.; Severud, L.K.

1980-01-01

238

Flexible ocean upwelling pipe  

DOEpatents

In an ocean thermal energy conversion facility, a cold water riser pipe is releasably supported at its upper end by the hull of the floating facility. The pipe is substantially vertical and has its lower end far below the hull above the ocean floor. The pipe is defined essentially entirely of a material which has a modulus of elasticity substantially less than that of steel, e.g., high density polyethylene, so that the pipe is flexible and compliant to rather than resistant to applied bending moments. The position of the lower end of the pipe relative to the hull is stabilized by a weight suspended below the lower end of the pipe on a flexible line. The pipe, apart from the weight, is positively buoyant. If support of the upper end of the pipe is released, the pipe sinks to the ocean floor, but is not damaged as the length of the line between the pipe and the weight is sufficient to allow the buoyant pipe to come to a stop within the line length after the weight contacts the ocean floor, and thereafter to float submerged above the ocean floor while moored to the ocean floor by the weight. The upper end of the pipe, while supported by the hull, communicates to a sump in the hull in which the water level is maintained below the ambient water level. The sump volume is sufficient to keep the pipe full during heaving of the hull, thereby preventing collapse of the pipe.

Person, Abraham (Los Alamitos, CA)

1980-01-01

239

State-of-the-art interior-piping-systems applications: Commercial buildings. Final report, June 1987June 1989  

Microsoft Academic Search

Four types of commercial buildings were identified as candidates for the use of semi-rigid tubing: low-rise offices, low-rise motels, retail buildings, and high-rise residential buildings. For each building type, design documents were obtained for a specific building. The installation costs for a conventional low-pressure rigid steel piping system and elevated-pressure (2-5 psig) corrugated stainless steel tubing and copper tubing semi-rigid

A. J. Willman; D. Stanton-Hoyle

1990-01-01

240

Giant Enhancement of Colloidal diffusion in a Corrugated Optical Vortex  

NASA Astrophysics Data System (ADS)

We experimentally study thermally driven velocity fluctuations of a Brownian particle in a tilted washboard potential. Our system consists of a single fluid-borne colloidal sphere driven by a holographically projected superposition of optical vortices. A single optical vortex is a ring-like optical trap created by focusing a helical mode of laser light. Torque exerted by an optical vortex's orbital angular momentum flux drives a trapped colloidal particle around its circumference. Superposing two optical vortices with opposite helicities and different amplitudes creates a corrugated optical vortex with sinusoidal intensity variations around its circumference. The resulting tilted washboard potential admits both static trapped states and dynamic running states. Digital video microscopy measurements of the resulting particle trajectories reveal a hundred-fold enhancement of the effective self-diffusion coefficient near the static-to-running transition.

Lee, Sang-Hyuk; Grier, David G.

2006-03-01

241

A Large L-Band Rectangular Corrugated Horn  

SciTech Connect

This paper describes a lightweight, corrugated-horn antenna, constructed from sheet metal. Over a 1.3-1.7 GHz operating band, its half-power beam width is approximately 20{sup o} in the E-plane and varies from 17{sup o} to 13{sup o} in the H-plane. Quarter-wave choke slots at the aperture help to reduce the E-plane sidelobes below -55 dB at angles greater than 90{sup o}, while the H-plane sidelobes lie in that range both with and without choke slots. Return loss throughout the operating band is -25 dB or below. Critical dimensions are provided, together with useful guidelines for designing similar antennas.

Witebsky, C.; Smoot, G.F.; Levin, S.; Bensadoun, M.

1987-01-01

242

Scaling of premixed turbulent flames in the corrugated regime  

SciTech Connect

A novel apparatus for studying premixed combustion, involving the flow through a wide-angled diffuser, is described. Flames in pure methane/air mixtures and in methane/hydrogen/air have been stabilised at various heights in the diffuser, with various types of turbulence generators at inlet. The stabilisation conditions thus embraced a range of turbulence levels and integral length scales in the corrugated flamelet regime. Particle image velocimetry and planar laser-induced fluorescence were deployed to obtain the instantaneous velocity field in the unburnt mixture and the location of the flame front. Ensemble averages over 200 images allowed the statistics for 2-D flamelet surface density and the thickness of the flame brush to be measured in flames that were nearly planar in the mean. The flamelet surface density S was shown to be related to the length scale and the turbulence level, albeit in a nonlinear manner. However, there was no clear correlation for the flame brush thickness {delta}{sub T}, two different perforated plates generating turbulence at the same level and of the same length scale but giving very different thicknesses. Integrating S across the flame and combining with information from elsewhere on the effect of stretch on the laminar burning velocity, the consumption speed was estimated. As in all determinations of this parameter in the literature, this was found to be very much less than the turbulent displacement speed. Residual mean flame curvature is not thought to be sufficient to account for this, and explanations are being sought in a more complex response of the flamelets to the turbulence than just pure corrugation. (author)

Lawn, C.J. [Department of Engineering, Queen Mary, University of London, Mile End Road, London, E1 4NS (United Kingdom); Schefer, R.W. [Combustion Research Facility, Sandia National Laboratories, Livermore, CA 94551-0969 (United States)

2006-07-15

243

Application of the method of integral equations to calculate the electrodynamic characteristics of periodically corrugated waveguides  

NASA Astrophysics Data System (ADS)

A method for calculating the electrodynamic characteristics of periodically corrugated waveguides is described which is based on the representation of the field as a solution of the Helmoltz vector equation in the form of a simple-layer potential, transformed using the Floquet conditions. Systems of mixed integral equations for the weight vector function of the simple-layer potential in azimuthally symmetric and helically corrugated waveguides are derived. A numerical implementation of the Fourier method is described in connection with finding the dispersion relation of azimuthally symmetric waves of a circular corrugated waveguide.

Belov, V. E.; Rodygin, L. V.; Fil'Chenkov, S. E.; Iunakovskii, A. D.

244

The effects of cell face curvature and corrugations on the stiffness and strength of metallic foams  

SciTech Connect

The measured mechanical properties of conventional lightweight metallic foams fall far short of those predicted by idealized models for closed cell foams. Their poor mechanical performance can be attributed, to a large extent, to curved and corrugated cell faces present within the foams. Idealized honeycombs and foams with idealized cell structure and curved or corrugated cell edges and faces are modeled using finite elements. The elastic modulus and plastic collapse stress of these honeycombs and foams are calculated relative to those of a comparable cellular material model with flat cell edges and faces. The results are presented in terms of the radius of curvature and the amplitude and frequency of the corrugation.

Simone, A.E.; Gibson, L.J. [Massachusetts Inst. of Tech., Cambridge, MA (United States)] [Massachusetts Inst. of Tech., Cambridge, MA (United States)

1998-07-01

245

Gyrokinetic simulations of off-axis minimum-q profile corrugations  

SciTech Connect

Quasiequilibrium radial 'profile corrugations' in the electron temperature gradient are found at lowest-order singular surfaces in global gyrokinetic code simulations of both monotonic-q and off-axis minimum-q discharges. The profile corrugations in the temperature and density gradients are time-averaged components of zonal flows. The m/n=2/1 electron temperature gradient corrugation is measurably large and appears to trigger an internal transport barrier as the off-axis minimum-q=2 surfaces enter the plasma.

Waltz, R.E.; Austin, M.E.; Burrell, K.H.; Candy, J. [General Atomics, P.O. Box 85608, San Diego, California 92186-5608 (United States)

2006-05-15

246

A corrugated perfect magnetic conductor surface supporting spoof surface magnon polaritons.  

PubMed

In this paper, we demonstrate that spoof surface magnon polaritons (SSMPs) can propagate along a corrugated perfect magnetic conductor (PMC) surface. From duality theorem, the existence of surface electromagnetic modes on corrugated PMC surfaces are manifest to be transverse electric (TE) mode compared with the transverse magnetic (TM) mode of spoof surface plasmon plaritons (SSPPs) excited on corrugated perfect electric conductor surfaces. Theoretical deduction through modal expansion method and simulation results clearly verify that SSMPs share the same dispersion relationship with the SSPPs. It is worth noting that this metamaterial will have more similar properties and potential applications as the SSPPs in large number of areas. PMID:24921768

Liu, Liang-Liang; Li, Zhuo; Gu, Chang-Qing; Ning, Ping-Ping; Xu, Bing-Zheng; Niu, Zhen-Yi; Zhao, Yong-Jiu

2014-05-01

247

Insulation for Piping.  

National Technical Information Service (NTIS)

A foamed insulation for cryogenic pipe lines comprised of a pair of preformed, semicircular foamed insulation half-sections is described. The faying surfaces are coated with a polyurethane adhesive and bonded together about the pipe. The faying surfaces o...

G. Lerma

1975-01-01

248

Flexible Pipe Technology.  

National Technical Information Service (NTIS)

The conference proceedings contain 12 papers. The topics covered are: Technology, products and offshore applications; Steel reinforced elastomer pipes - Design approach and performance characteristics; Flexible pipe installation techniques; Gullfaks ''A''...

1986-01-01

249

Pipe selection guide  

SciTech Connect

Four parameters are used to define a particular pipe: inside diameter, wall thickness, material, and ends. The factors influencing pipe selection are limited to fluid pressure, temperature, chemistry, flow rate, and cost. Other pipe parameters and factors that influence pipe selection and design are mentioned, and, where appropriate, the user is warned that at some stage in the project these factors must be dealt with. It is assumed that the objective is the direct application of geothermal water at temperatures lower than 200/sup 0/F and with 12-in. or smaller pipe. When considering friction losses for sizing purposes, only straight pipe is considered. A discussion of the characteristics and attributes of readily available pipe is included to aid in making a preliminary selection. Energy loss from buried pipe is considered.

Sanders, R.D.

1982-04-01

250

Miniature Heat Pipes.  

National Technical Information Service (NTIS)

Small Business Innovation Research contracts from Goddard Space Flight Center to Thermacore Inc. have fostered the company work on devices tagged 'heat pipes' for space application. To control the extreme temperature ranges in space, heat pipes are import...

1997-01-01

251

Heat pipes. [technology utilization  

NASA Technical Reports Server (NTRS)

The development and use of heat pipes are described, including space requirements and contributions. Controllable heat pipes, and designs for automatically maintaining a selected constant temperature, are discussed which would add to the versatility and usefulness of heat pipes in industrial processing, manufacture of integrated circuits, and in temperature stabilization of electronics.

1975-01-01

252

14. DETAIL OF SOUTHWEST FRONT OF WAREHOUSE, SHOWING CORRUGATED PLASTER/ASBESTOS ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

14. DETAIL OF SOUTHWEST FRONT OF WAREHOUSE, SHOWING CORRUGATED PLASTER/ASBESTOS WALLS, WINDOWS AND ROOF. VIEW TO NORTHEAST. - Commercial & Industrial Buildings, International Harvester Company Showroom, Office & Warehouse, 10 South Main Street, Dubuque, Dubuque County, IA

253

Corrugation of Phase-Separated Lipid Bilayers Supported by Nanoporous Silica Xerogel Surfaces.  

National Technical Information Service (NTIS)

Lipid bilayers supported by substrates with nanometer-scale surface corrugations holds interest in understanding both nanoparticle-membrane interactions and the challenges of constructing models of cell membranes on surfaces with desirable properties, e.g...

B. A. Nellis, E. I. Goksu, J. H. Satcher, J. T. Groves, M. L. Longo, S. H. Risbud, W. C. Lin

2008-01-01

254

``Cold'' dispersion relation of corrugated waveguide filled with plasma immersed in a finite magnetic field  

Microsoft Academic Search

A general dispersion equation of a partially filled plasma corrugated waveguide immersed in a finite magnetic field is presented. When the guiding magnet B0rightarrowinfty or 0, this equation can be reduced to the results obtained in previous works.

Wei Li; Yan-Yu Wei; Hong-Quan Xie; Sheng-Gang Liu; Ma-Li Gong

2003-01-01

255

Pipe Line Control  

NASA Technical Reports Server (NTRS)

The array of tanks, pipes and valves in the photo below is a petroleum tank farm in Georgia, part of a petrochemical pipe line system that moves refined petroleum products from Texas and Louisiana to the mid-Eastern seaboard. The same pipes handle a number of different products, such as gasoline, kerosene, jet fuel or fuel oil. The fluids are temporarily stored in tanks, pumped into the pipes in turn and routed to other way stations along the pipe line. The complex job of controlling, measuring and monitoring fuel flow is accomplished automatically by a computerized control and communications system which incorporates multiple space technologies.

1978-01-01

256

85-115 GHz corrugated conical horn antenna for the radio telescope system  

Microsoft Academic Search

The fabrication and design, based on cylindrical mode theory, for the analysis of the horn, and the vector integral method compared with Gaussian-Laguerre modes for the radiation pattern for the MM-wave corrugated conical horn feeder are determined. To design the corrugated horn in the MM-wave range, the considerations of both the excitation of the balanced hybrid mode and practical manufacturing

Taeho Son; Seog-Tae Han; Byungsoo Lee

2001-01-01

257

The Impact of Slow-Wave Modes on the Radiation Performance of a Corrugated Horn Antenna  

Microsoft Academic Search

Corrugated horn antennas offer many advantages compared with other waveguide radiators. A major disadvantage which is inherent\\u000a with the design of a corrugated horn is the fact that slow-wave modes may exist within the horn antenna. In this paper far-field\\u000a measurements of a W-band horn antenna are presented. The experimental data is compared with simulated data to confirm the\\u000a presence

Philipp Fürholz; Axel Murk

2010-01-01

258

Self-Consistent Nonlinear Theory and Simulation of Gyro-TWT With Helically Corrugated Waveguide  

Microsoft Academic Search

We present the transmission equations and dispersion equations of a helically corrugated waveguide according to the coupling wave theory and the impedance perturbation method. We analyzed the field distribution of the helically corrugated waveguide according to the dispersion equations. We developed the self-consistent nonlinear equations of beam–wave interaction through studying the self-consistent nonlinear theory of beam–wave interaction in a gyrotron

Shiqiu Zhu; Efeng Wang; Hongfu Li; Hao Li; Jinjun Feng

2012-01-01

259

High-efficiency wideband gyro-TWTs and gyro-BWOs with helically corrugated waveguides  

Microsoft Academic Search

We review the studies of gyrotron-type microwave devices whose electrodynamic system has the form of an oversized metal waveguide\\u000a with a helically corrugated internal surface. For certain parameters, such a corrugation changes radically the waveguide dispersion\\u000a ensuring an almost constant group velocity of the eigenmode for a small (close to zero) longitudinal wave number in a wide\\u000a frequency band. The

V. L. Bratman; G. G. Denisov; S. V. Samsonov; A. W. Cross; A. D. R. Phelps; W. Xe

2007-01-01

260

A W-Band Gyro-BWO using a helically corrugated waveguide  

Microsoft Academic Search

This paper presents the design of a W-band gyro-BWO with a helically corrugated waveguide and a cusp electron gun. Results are presented of simulations of the cusp gun and microwave measurements of the interaction region using a vector network analyser. Over the frequency range 85-105 GHz the helically corrugated waveguide was found to have an average loss of just under

Craig Ross Donaldson; Wenlong He; A. D. R. Phelps; A. W. Cross; K. Ronald; A. R. Young; C. G. Whyte; Fengping Li

2008-01-01

261

A ?10kW W-Band Gyro-BWO using a helically corrugated waveguide  

Microsoft Academic Search

Presented in this paper are the results of a 10 kW W-Band Gyro-BWO based on a helically corrugated interaction region and novel cusp electron gun. Microwave measurements of the helically corrugated interaction region are shown to give a low loss of 1dB over the frequency region of interest (84-104 GHz). The measured dispersion was found in good agreement with the

Craig R. Donaldson; Wenlong He; A. D. R. Phelps; Fengping Li; A. W. Cross; K. Ronald; A. R. Young; C. G. Whyte

2008-01-01

262

Corrugated waveguide and directional coupler for CW 250GHz gyrotron DNP experiments  

Microsoft Academic Search

A 250-{GHz} corrugated transmission line with a directional coupler for forward and backward power monitoring has been constructed and tested for use with a 25-W continuous-wave gyrotron for dynamic nuclear polarization {(DNP)} experiments. The main corrugated line (22-mm internal diameter, 2.4-m long) connects the gyrotron output to the {DNP} probe input. The directional coupler, inserted approximately midway, is a four-port

Paul P. Woskov; Vikram S. Bajaj; Melissa K. Hornstein; Richard J. Temkin; Robert G. Griffin

2005-01-01

263

Numerical Investigation of Flow and Heat Transfer in Corrugated Sinusoidal Wavy Channel  

Microsoft Academic Search

A three-dimensional numerical investigation of fluid flow and heat transfer in corrugated sinusoidal wavy channels with uniform wall temperature is performed for air (Pr=0.696) in the low Reynolds numbers regime (Re=40~1000). Constant properties, periodically fully developed laminar flow and heat transfer are considered. The effects of channel plate spacing (?), plate corrugation severity (?) and air mass flow rate (Re)

Jixiang Yin; Gang Yang; Guifang Hao; Ping Lv

2011-01-01

264

Analysis of Propagation Characteristics of Circular Corrugated Waveguides Using Coupled Integral Equation Technique  

Microsoft Academic Search

The circular corrugated waveguides are useful as slow-wave circuits in traveling-wave tube amplifiers, linear accelerators, and backward-wave oscillators. The study of propagation characteristic of TM waves in circular corrugated waveguides is important for applications such as those above and is the focus of this paper. The propagation characteristics are computed using the coupled integral equation technique (CIET). Both infinitesimally thin

V. Latha Christie; Lalit Kumar; N. Balakrishnan

2007-01-01

265

Critical instability and friction scaling of fluid flows through pipes with rough inner surfaces.  

PubMed

It has been shown experimentally over nearly 80 years that surface fine roughness of circular pipes has a crucial effect on the natural transition to turbulence. In this Letter, a theoretical explanation is suggested for the roughness-induced instability. Once the nonlinear effect of roughness is introduced (through a pipe with fine corrugation surface), the mean velocity profile becomes unstable to three-dimensional, asymmetric, and helical traveling waves at moderate Reynolds numbers. The threshold of the aspect ratio or shape factor of the roughness element required to cause instability scales as Re-2. Inspired by the current model, a scaling form is proposed and the scaled friction factor measurements in rough pipes collapse onto a universal curve. PMID:20366316

Tao, Jianjun

2009-12-31

266

Critical Instability and Friction Scaling of Fluid Flows through Pipes with Rough Inner Surfaces  

NASA Astrophysics Data System (ADS)

It has been shown experimentally over nearly 80 years that surface fine roughness of circular pipes has a crucial effect on the natural transition to turbulence. In this Letter, a theoretical explanation is suggested for the roughness-induced instability. Once the nonlinear effect of roughness is introduced (through a pipe with fine corrugation surface), the mean velocity profile becomes unstable to three-dimensional, asymmetric, and helical traveling waves at moderate Reynolds numbers. The threshold of the aspect ratio or shape factor of the roughness element required to cause instability scales as Re-2. Inspired by the current model, a scaling form is proposed and the scaled friction factor measurements in rough pipes collapse onto a universal curve.

Tao, Jianjun

2009-12-01

267

Corrugator Muscle Responses Are Associated With Individual Differences in Positivity-Negativity Bias  

PubMed Central

Corrugator supercilii muscle activity is considered an objective measure of valence because it increases in response to negatively valenced facial expressions (angry) and decreases to positive expressions (happy). The authors sought to determine if corrugator activity could be used as an objective measure of positivity-negativity bias. The authors recorded corrugator responses as participants rated angry, happy, and surprised faces as “positive” or “negative.” The critical measure of bias was the percentage of positive versus negative ratings assigned to surprised faces by each participant. Reaction times for surprise expressions were longer than for happy and angry expressions, consistent with their ambiguous valence. Participants who tended to rate surprised faces as negative showed increased corrugator activity to surprised faces, whereas those who tended to rate surprise as positive showed decreased activity. Critically, corrugator responses reflected the participants’ bias (i.e., their tendency to rate surprise as positive or negative). These data show that surprised faces constitute a useful tool for assessing individual differences in positivity-negativity bias, and that corrugator activity can objectively reflect this bias.

Neta, Maital; Norris, Catherine J.; Whalen, Paul J.

2009-01-01

268

Corrugator muscle responses are associated with individual differences in positivity-negativity bias.  

PubMed

Corrugator supercilii muscle activity is considered an objective measure of valence because it increases in response to negatively valenced facial expressions (angry) and decreases to positive expressions (happy). The authors sought to determine if corrugator activity could be used as an objective measure of positivity-negativity bias. The authors recorded corrugator responses as participants rated angry, happy, and surprised faces as "positive" or "negative." The critical measure of bias was the percentage of positive versus negative ratings assigned to surprised faces by each participant. Reaction times for surprise expressions were longer than for happy and angry expressions, consistent with their ambiguous valence. Participants who tended to rate surprised faces as negative showed increased corrugator activity to surprised faces, whereas those who tended to rate surprise as positive showed decreased activity. Critically, corrugator responses reflected the participants' bias (i.e., their tendency to rate surprise as positive or negative). These data show that surprised faces constitute a useful tool for assessing individual differences in positivity-negativity bias, and that corrugator activity can objectively reflect this bias. PMID:19803586

Neta, Maital; Norris, Catherine J; Whalen, Paul J

2009-10-01

269

Transfer-matrix approach based on modal analysis for modeling corrugated long-period fiber gratings.  

PubMed

A transfer-matrix method is developed for modeling a corrugated long-period fiber grating. Cladding-mode resonance in such a corrugated structure can be controlled by the applied tensile stress based on the photoelastic effect. A first-order vectorial perturbation expansion is used to derive the mode fields of the two basic regions under the strain-induced index perturbation. Because the etched cladding radius is much smaller than the unetched radius, the effect of the corrugated structure on cladding modes cannot be treated as a small perturbation. Thus the conventional coupled-mode theory is inadequate for the modeling of such a structure. Based on a self-consistent mode-matching technique, mode coupling within the corrugated structure can be described by a set of transfer matrices. We apply the formulation to the calculation of the transmission spectra of a corrugated long-period grating and compare the calculated with the experimental results. The transfer-matrix approach is found to account well for the features of the transmission spectra of the corrugated long-period gratings. PMID:18360487

Chern, G W; Wang, L A; Lin, C Y

2001-09-01

270

Effect of track irregularities on initiation and evolution of rail corrugation  

NASA Astrophysics Data System (ADS)

The effect of track irregularities on rail corrugation is investigated in detail with the numerical method when a wheelset is steadily curving. The irregularities considered in the analysis include initial running surface of rail with periodically varying and different wave length, stochastic roughness on the rail running surface, and vertical uneven support stiffness of the rail due to the discrete sleeper supports. The numerical method considers a combination of Kalker's rolling contact theory with non-Hertzian to be modified, a linear frictional work model and a vertical dynamics model of railway vehicle coupled with a curved track. The model is also validated by an experiment with a full scale facility. The influence of different speeds of wheelset curving on the development of the corrugation is taken into account in the calculation. The numerical results indicate that (1) for existing of the initial corrugation of new rail with any wavelength the depth from the peak to trough of it decreases gradually with an increase of wheelset passage, but the initial corrugation evolved has a tendency to move in the rolling direction, (2) the amplitude of the initial stochastic roughness of new rail is gradually leveled out and but a corrugation with very small depth and a few fixed passing frequencies is initiated, the passing frequencies are the same as the natural frequencies of the track, and (3) the discrete rail supports by sleepers have a great influence on the formation of the corrugation.

Jin, X. S.; Wen, Z. F.; Wang, K. Y.

2005-07-01

271

Oceanic corrugated surfaces and the strength of the axial lithosphere at slow spreading ridges  

NASA Astrophysics Data System (ADS)

We analyse the topography and gravity signature of 39 corrugated surfaces formed over the past 26 myrs in the footwall of axial detachment faults at the eastern Southwest Indian Ridge. These corrugated surfaces appear to have formed at a melt supply about half the global melt supply average for mid-ocean ridges, and we find that their presently elevated topography, relative to adjacent non-corrugated seafloor, was mostly acquired at the end of their formation, at the "termination stage". This configuration, which also characterizes many off-axis corrugated surfaces in other oceans, suggests that the plate flexural rigidity was very low during the formation of the corrugated surface, and increased significantly at the termination stage. Following Buck (1988), we hypothesize that stresses related to bending of the plate cause internal deformation and damage in the footwall of the fault, which is associated with weakening. As a possible mechanism for enhanced footwall weakening while corrugated surfaces form, we propose the formation of weak shear zones coated with hydrous minerals such as talc, amphibole, chlorite and serpentine, in mantle-derived ultramafics next to gabbro intrusions. If this hypothesis is correct, the amount of footwall weakening and roll-over along axial detachment faults at slow spreading ridges may be controlled both by access to hydrothermal fluids in the footwall of the detachment, and by the abundance and distribution of gabbros intrusions in exhumed ultramafics.

Cannat, Mathilde; Sauter, Daniel; Escartín, Javier; Lavier, Luc; Picazo, Suzanne

2009-10-01

272

65. FIRE SUPPRESSION PIPES BEHIND FLAME BUCKET. PIPES TO UMBILICAL ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

65. FIRE SUPPRESSION PIPES BEHIND FLAME BUCKET. PIPES TO UMBILICAL MAST IN LOWER LEFT CORNER; PIPES TO LAUNCHER IN UPPER LEFT CORNER; PIPES TO FLAME BUCKET IN LOWER RIGHT CORNER OF PHOTOGRAPH. POTABLE WATER PIPING IN UPPER RIGHT CORNER OF PHOTO. - Vandenberg Air Force Base, Space Launch Complex 3, Launch Pad 3 East, Napa & Alden Roads, Lompoc, Santa Barbara County, CA

273

Corrugated Quantum Well Infrared Photodetector Focal Plane Array Test Results  

NASA Technical Reports Server (NTRS)

The corrugated quantum-well infrared photodetector (C-QWIP) uses total internal reflection to couple normal incident light into the optically active quantum wells. The coupling efficiency has been shown to be relatively independent of the pixel size and wavelength thus making the C-QWIP a candidate for detectors over the entire infrared spectrum. The broadband coupling efficiency of the C-QWIP makes it an ideal candidate for multiwavelength detectors. We fabricated and tested C-QWIP focal plane arrays (FPAs) with cutoff wavelengths of 11.2 and 16.2 micrometers. Each FPA has 256 x 256 pixels that are bump-bonded to a direct injection readout circuit. Both FPAs provided infrared imagery with good aesthetic attributes. For the 11.2-micrometers FPA, background-limited performance (BLIP) was observed at 60 K with f/3 optics. For the 16.2-micrometers FPA, BLIP was observed at 38 K. Besides the reduction of dark current in C-QWIP structures, the measured internal quantum efficiency (eta) remains to be high. The values for responsivity and quantum efficiency obtained from the FPA results agree well with those measured for single devices.

Goldberg, A.; Choi, K. K.; Das, N. C.; La, A.; Jhabvala, M.

1999-01-01

274

On the Performance of Printed Dipole Antenna With Novel Composite Corrugated-Reflectors for Low-Profile Ultrawideband Applications  

Microsoft Academic Search

An investigation of the performance of printed dipole antenna with finite periodically corrugated-reflectors for low-profile ultrawideband (UWB) applications is presented. According to the relative orientations of the linear-polarized source antenna and the corrugated-reflectors, the problem could be divided into H and E cases. Their fundamental differences and design guidelines are discussed in detail. A novel composite corrugated-reflector based on the

Qi Wu; Ronghong Jin; Junping Geng; Donglin Su

2010-01-01

275

Piping Cracks in JPDR, (III)  

Microsoft Academic Search

Failure analysis was made on samples taken from type 304 stainless steel piping systems (core spray, unloading and feed water pipes) that had cracked in service. In the core spray pipe, large cracks including one penetrating through the wall were found in the upper half of the pipe wall, within the heat-affected zone of the weld joint between the pipe

Yutaka OGAWA; Masami SHINDO; Masahiko KIKUCHI

1979-01-01

276

Involvement in plastic pipe  

SciTech Connect

Vested with the responsibility of writing plastic pipe standards, ASTM's Subcommittee D20.17 on Thermoplastic Pipe and Fittings (later reorganized as a full committee, F-17) compiled many of the test methods and standards now accepted by local, state, and federal agencies. One of the most comprehensive piping specifications under F-17's jurisdiction covers gas-pressure piping materials including cellusone acetate butyrate, acrylonitrile butadiene styrene, high- and normal-impact polyvinyl chloride, a variety of polyethylenes, and polybutylene. All of these materials have been used for gas distribution service, some dating back to 1942. As of 1982, figures show that 200,000 miles of all sizes of plastic gas pipe for both gas services and mains have been installed, representing 16.5% of the total gas distribution system in the US. From a handful of early pioneers, the number of utilities using plastic pipe now stands at 933.

Buczala, G.S.; Walker, R.P.

1983-08-01

277

Deployable Heat Pipe Radiator  

NASA Technical Reports Server (NTRS)

A 1.2- by 1.8-m variable conductance heat pipe radiator was designed, built, and tested. The radiator has deployment capability and can passively control Freon-21 fluid loop temperatures under varying loads and environments. It consists of six grooved variable conductance heat pipes attached to a 0.032-in. aluminum panel. Heat is supplied to the radiator via a fluid header or a single-fluid flexible heat pipe header. The heat pipe header is an artery design that has a flexible section capable of bending up to 90 degrees. Radiator loads as high as 850 watts were successfully tested. Over a load variation of 200 watts, the outlet temperature of the Freon-21 fluid varied by 7 F. An alternate control system was also investigated which used a variable conductance heat pipe header attached to the heat pipe radiator panel.

Edelstein, F.

1975-01-01

278

Miniature Heat Pipes  

NASA Technical Reports Server (NTRS)

Small Business Innovation Research contracts from Goddard Space Flight Center to Thermacore Inc. have fostered the company work on devices tagged "heat pipes" for space application. To control the extreme temperature ranges in space, heat pipes are important to spacecraft. The problem was to maintain an 8-watt central processing unit (CPU) at less than 90 C in a notebook computer using no power, with very little space available and without using forced convection. Thermacore's answer was in the design of a powder metal wick that transfers CPU heat from a tightly confined spot to an area near available air flow. The heat pipe technology permits a notebook computer to be operated in any position without loss of performance. Miniature heat pipe technology has successfully been applied, such as in Pentium Processor notebook computers. The company expects its heat pipes to accommodate desktop computers as well. Cellular phones, camcorders, and other hand-held electronics are forsible applications for heat pipes.

1997-01-01

279

Abrasion resistant heat pipe  

DOEpatents

A specially constructed heat pipe is described for use in fluidized bed combustors. Two distinct coatings are spray coated onto a heat pipe casing constructed of low thermal expansion metal, each coating serving a different purpose. The first coating forms aluminum oxide to prevent hydrogen permeation into the heat pipe casing, and the second coating contains stabilized zirconium oxide to provide abrasion resistance while not substantially affecting the heat transfer characteristics of the system.

Ernst, D.M.

1984-10-23

280

Abrasion resistant heat pipe  

DOEpatents

A specially constructed heat pipe for use in fluidized bed combustors. Two distinct coatings are spray coated onto a heat pipe casing constructed of low thermal expansion metal, each coating serving a different purpose. The first coating forms aluminum oxide to prevent hydrogen permeation into the heat pipe casing, and the second coating contains stabilized zirconium oxide to provide abrasion resistance while not substantially affecting the heat transfer characteristics of the system.

Ernst, Donald M. (Leola, PA)

1984-10-23

281

Heat pipe investigations  

NASA Technical Reports Server (NTRS)

The OAO-C spacecraft has three circular heat pipes, each of a different internal design, located in the space between the spacecraft structural tube and the experiment tube, which are designed to isothermalize the structure. Two of the pipes are used to transport high heat loads, and the third is for low heat loads. The test problems deal with the charging of the pipes, modifications, the mobile tilt table, the position indicator, and the heat input mechanisms. The final results showed that the techniques used were adequate for thermal-vacuum testing of heat pipes.

Marshburn, J. P.

1972-01-01

282

Internal pipe attachment mechanism  

DOEpatents

An attachment mechanism is described for repairing or extending fluid carrying pipes, casings, conduits, etc. utilizing one-way motion of spring tempered fingers to provide a mechanical connection between the attachment mechanism and the pipe. The spring tempered fingers flex to permit insertion into a pipe to a desired insertion depth. The mechanical connection is accomplished by reversing the insertion motion and the mechanical leverage in the fingers forces them outwardly against the inner wall of the pipe. A seal is generated by crushing a sealing assembly by the action of setting the mechanical connection. 6 figures.

Bast, R.M.; Chesnut, D.A.; Henning, C.D.; Lennon, J.P.; Pastrnak, J.W.; Smith, J.A.

1994-12-13

283

Reference Piping Design Stress Analysis.  

National Technical Information Service (NTIS)

A history of the piping stress analysis is presented, tracing the work done from the conceptual stage to the final reference design layout. The piping stress analysis of the final reference design piping layout is also presented.

S. Mathias S. Westerman

1973-01-01

284

Smoke Production of Nonmetallic Pipes.  

National Technical Information Service (NTIS)

The smoke production of nonmetallic pipes was investigated using 'Test Method for Specific Optical Density of Smoke Generated by Solid Materials,' ASTM E 662. The pipe samples consisted of two epoxy resin glass reinforced pipes, two vinyl ester resin glas...

W. H. McLain L. Nash

1995-01-01

285

Bridges and Culverts.  

National Technical Information Service (NTIS)

The 16 papers in this report deal with the following areas: field testing of the Fremont Bridge; seismic design of curved box girders; test to failure of the Hannacroix Creek Bridge; load factor design applied to truss members in design of Greater New Orl...

M. J. Koob J. M. Hanson C. P. Heins I. C. Lin D. B. Beal

1983-01-01

286

Optomechanic interaction in a corrugated phoxonic nanobeam cavity  

NASA Astrophysics Data System (ADS)

The interaction between phonons and photons is investigated theoretically in a phoxonic cavity inside a corrugated nanobeam waveguide presenting band gaps for both electromagnetic and elastic waves. The structure is made by drilling periodic holes on a silicon nanobeam with lateral periodic stubs and the tapered cavity is constructed by changing gradually the geometrical parameters of both the holes and stubs. We show that this kind of cavity displays localized phonons and photons inside the gaps, which can enhance their interaction and also promotes the presence of many optical confined modes with high quality factor. Using the finite-element method, we demonstrate that with appropriate design of the tapering construction, one can control the cavity modes frequency without altering significantly the quality factor of the photonic modes. By changing the tapering rates over the lattice constants, we establish the possibility of shifting the phononic cavity modes frequency to place them inside the desired gap, which enhances their confinement and increases the mechanical quality factor while keeping the strength of the optomechanic coupling high. In our calculations, we take account of both mechanisms that contribute to the acousto-optic interaction, namely photoelastic and interface motion effects. We show that in our case, these two effects can contribute additively to give high coupling strength between phononic and photonic cavity modes. The calculations of the coupling coefficient which gives the phonon-photon coupling strength give values as high as 2 MHz while photonic cavity modes display quality factor of 105 and even values up to 3.4 MHz but with smaller photonic quality factors.

Oudich, Mourad; El-Jallal, Said; Pennec, Yan; Djafari-Rouhani, Bahram; Gomis-Bresco, Jordi; Navarro-Urrios, Daniel; Sotomayor Torres, Clivia M.; Martínez, Alejandro; Makhoute, Abdelkader

2014-06-01

287

Partially corrugated waveguide laser diodes for use in CATV networks  

NASA Astrophysics Data System (ADS)

Recent CATV network systems require high power (Po >= 20 mW), wide band (1 GHz) and low distortion light sources for use in high capacity network schemes. Furthermore, cost effective light sources are also needed for use in narrowing services. We have developed high performance, 1.3-micrometers partially corrugated waveguide laser diodes (PC-LDs) suitable for use in such CATV networks. The production yield of these PC-LDs with respect to low distortion specifications has been improved about three times over that of conventional distributed feedback (DFB) LDs, and this can be attributed to their characteristic of not being sensitive to grating phases as well as their flat electric field profile along the cavities. Excellent low distortion characteristics (a composite second-order distortion

Yamada, Hirohito; Okuda, Tetsuro; Huang, Yi-Dong; Muroya, Yoshiharu; Torikai, Toshitaka

1997-05-01

288

Coherent mode coupling in highly efficient top-emitting OLEDs on periodically corrugated substrates.  

PubMed

Bragg scattering at one-dimensional corrugated substrates allows to improve the light outcoupling from top-emitting organic light-emitting diodes (OLEDs). The OLEDs rely on a highly efficient phosphorescent pin stack and contain metal electrodes that introduce pronounced microcavity effects. A corrugated photoresist layer underneath the bottom electrode introduces light scattering. Compared to optically optimized reference OLEDs without the corrugated substrate, the corrugation increases light outcoupling efficiency but does not adversely affect the electrical properties of the devices. The external quantum efficiency (EQE) is increased from 15 % for an optimized planar layer structure to 17.5 % for a corrugated OLED with a grating period of 1.0 ?m and a modulation depth of about 70 nm. Detailed analysis and optical modeling of the angular resolved emission spectra of the OLEDs provide evidence for Bragg scattering of waveguided and surface plasmon modes that are normally confined within the OLED stack into the air-cone. We observe constructive and destructive interference between these scattered modes and the radiative cavity mode. This interference is quantitatively described by a complex summation of Lorentz-like resonances. PMID:24718126

Schwab, Tobias; Fuchs, Cornelius; Scholz, Reinhard; Zakhidov, Alexander; Leo, Karl; Gather, Malte C

2014-04-01

289

The heat pipe  

Microsoft Academic Search

The heat pipe is a device having a high thermal conductance which utilizes the transport of a vapour and rejection of latent heat to achieve efficient thermal energy transport. The theory of heat pipes is well developed. Their use in applications involving temperatures in the cryogenic regime, and with development units running as high as 2000 degrees C, shows that

P. D. Dunn; D. A. Reay

1973-01-01

290

Loop heat pipes  

Microsoft Academic Search

Loop heat pipes (LHPs) are two-phase heat-transfer devices with capillary pumping of a working fluid. They possess all the main advantages of conventional heat pipes, but owing to the original design and special properties of the capillary structure are capable of transferring heat efficiency for distances up to several meters at any orientation in the gravity field, or to several

Yu. F. Maydanik

2005-01-01

291

Heat pipe technology issues  

SciTech Connect

Critical high temperature, high power applications in space nuclear power designs are near the current state of the art of heat pipe technology in terms of power density, operating temperature, and lifetime. Recent heat pipe development work at Los Alamos National Laboratory has involved performance testing of typical space reactor heat pipe designs to power levels in excess of 19 kW/cm/sup 2/ axially and 300 W/cm/sup 2/ radially at temperatures in the 1400 to 1500 K range. Operation at conditions in the 10 kW/cm/sup 2/ range has been sustained for periods of up to 1000 hours without evidence of performance degradation. The effective length for heat transport in these heat pipes was from 1.0 to 1.5 M. Materials used were molybdenum alloys with lithium employed as the heat pipe operating fluid. Shorter, somewhat lower power, molybdenum heat pipes have been life tested at Los Alamos for periods of greater than 25,000 hours at 1700 K with lithium and 20,000 hours at 1500/sup 0/K with sodium. These life test demonstrations and the attendant performance limit investigations provide an experimental basis for heat pipe application in space reactor design and represent the current state-of-the-art of high temperature heat pipe technology.

Merrigan, M.A.

1984-04-01

292

Apparatus for cleaning pipe  

SciTech Connect

This patent describes an apparatus for cleaning pipe having a pipe interior, the apparatus comprising: a rigid, longitudinally extending stem; a motor stationarily mounted on the stem; an outer body which surrounds the motor; drive means for connecting the motor to the outer body; a power coupling connected to the stem for supplying power to the motor.

Allison, A.; Tarsha, S.; McMillan, J.S.

1992-02-25

293

Heat pipe development status  

SciTech Connect

Test heat pipes have been operated in the 1400 K to 1700 K range for periods in excess of 20,000 hours with the objective of understanding and controlling corrosion and failure mechanisms. The results of a post test analysis of one of these heat pipes that was operated for 25,216 hours at 1700 K are reviewed and the implications for heat pipe lifetime discussed. An in-process report of an investigation of transient heat pipe behavior is presented. This investigation is being conducted as a result of restart problems encountered during life test of a 2 m. radiation cooled heat pipe. The results of a series of shut-down tests from power and temperature are given and probable causes of the restart problem discussed.

Merrigan, M.A.

1984-01-01

294

Pipe wiper system  

SciTech Connect

This patent describes improvement in a pipe wiper assembly for stripping fluid from the outer surface of a well string. The assembly comprises: a container having side walls, a pair of pipe wiper blades situated within the container and movable between an open position, wherein they are disassociated from the well string, and a closed position, wherein they are pressed against the well string. The improvement comprises: a frame situated within the container, for limited horizontal movement therein, having a horizontal guideway to accept the pipe wiper blades for movement from opposite sides of the well string between the open and the closed positions; a pair of fluid power cylinder assemblies for each of the pipe wiper blades, mounted on the frame, arranged for linking the frame and the pipe wiper blade for movement between the open and the closed positions; and flexible means, connected to the fluid power cylinder assembly, for supplying fluid power thereto.

Reddock, J.A.

1991-01-08

295

Extendable pipe crawler  

DOEpatents

A pipe crawler is described having a front leg assembly and a back leg assembly connected together by two air cylinders, each leg assembly having four extendable legs and a pair of actuators for sliding the extendable legs radially outward to increase the range of the legs when the pipe crawler enters a section of a pipe having a larger diameter. The crawler crawls by inchworm'-like motion, the front leg assembly and back leg assembly alternately engaging and disengaging the wall of the pipe to hold the pipe crawler as the air cylinders alternately advance the front leg assembly and bring up the rear leg assembly. The pair of actuators of each leg assembly are parallel, adjacent and opposing acting so that each slides two adjacent extendable legs radially outward. 5 figures.

Hapstack, M.

1991-05-28

296

Reduction of out-of-plane warpage in surface micromachined beams using corrugation  

NASA Astrophysics Data System (ADS)

Corrugation is proposed as a means of reducing the out-of-plane warpage in surface micromachined beams that result from an asymmetric vertical stress profile. Corrugation increases beam bending stiffness without increasing film thickness, making the beam more immune to intrinsic vertical stress gradients without requiring longer film deposition times, increased beam mass, or careful stress optimization. The technique was tested using a dual-thickness metal surface micromachining process with a photoresist sacrificial layer. Several corrugation patterns and geometries were tested, and the best performing pattern was implemented on a MEMS actuator array. The off-state to on-state capacitance delta of the array improved from 0.24 to 0.7pF and the beam curvature decreased from 180 to 50 nm compared with an uncorrugated array. Other device performance parameters, such as 30 V pull-in voltage and 5 billion cycle switching lifetime, were unaffected.

Gupta, Arun; Barron, Lance; Brainin, Michael; Lee, Jeong-Bong

2014-06-01

297

Density functional theory analysis of flexural modes, elastic constants, and corrugations in strained graphene  

NASA Astrophysics Data System (ADS)

Ab initio density functional theory has been used to analyze flexural modes, elastic constants, and atomic corrugations on single- and bi-layer graphene. Frequencies of flexural modes are sensitive to compressive stress; its variation under stress can be related to the anomalous thermal expansion via a simple model based in classical elasticity theory [P. L. de Andres, F. Guinea, and M. I. Katsnelson, Phys. Rev. BPRBMDO1098-012110.1103/PhysRevB.86.144103 86, 144103 (2012)]. Under compression, flexural modes are responsible for a long-wavelength rippling with a large amplitude and a marked anharmonic behavior. This is compared with corrugations created by thermal fluctuations and the adsorption of a light impurity (hydrogen). Typical values for the later are in the sub-Angstrom regime, while maximum corrugations associated to bending modes quickly increase up to a few Angstroms under a compressive stress, due to the intrinsic instability of flexural modes.

de Andres, P. L.; Guinea, F.; Katsnelson, M. I.

2012-12-01

298

Optimization of a corrugated millimeter-wave waveguide and a miter bend by FDTD simulation  

NASA Astrophysics Data System (ADS)

We estimate the transmission efficiency of the electromagnetic wave through the system composed of waveguide and miter bend by Finite-Difference Time-Domain (FDTD) simulation. As the fisrt approach of this estimation, we choose the case that the input wave is TE11 mode. In this case, the efficiency is estimated as 99.65 % for the system without grooves and 76.48 % for the system with grooves (which is called as "corrugate"). Comparing the distributions of the input electric field with that of the output electric field, the effect of the grooves is found as follows: Because the TE11 mode has an anisotropy, its shape is changed by the miter bend. This property appears in the corrugated system more strongly than the non-corrugated system.

Nakamura, H.; Kashima, N.; Takayama, A.; Sawada, K.; Tamura, Y.; Fujiwara, S.; Kubo, S.

2013-02-01

299

Railscan: A Tool for the Detection and Quantification of Rail Corrugation  

NASA Astrophysics Data System (ADS)

Rail corrugation is a phenomenon that leads to a waving in the rails with wavelengths typically between 3 cm and 100 cm and amplitude levels of several microns. The genesis of this waving is complex. Rail corrugation is a recognized problem that leads to excess vibration on the rails and vehicles to a point of reducing their life span and compromising safety. In urban areas excess vibration noise is also a problem. A software tool was developed to analyze accelerometer signals acquired in the boggies of rail vehicles in order to quantify the rail corrugation according to their frequency and amplitude. A wavelet packet methodology was used in this work and compared with the One Third Octave Filter (OTOF) power representations, which is currently used in the industry. It is shown that the former produces better results.

Gomes, Rui; Batista, Arnaldo; Ortigueira, Manuel; Rato, Raul; Baldeiras, Marco

300

Two-color corrugated quantum-well infrared photodetector for remote temperature sensing  

SciTech Connect

A quantum-well infrared photodetector (QWIP) based on the corrugated light-coupling scheme has been fabricated and tested for remote temperature sensing. The QWIP consists of two stacks of multiple quantum wells (MQWs), each sensitive in one of the atmospheric infrared transmission windows and each with a separate readout circuit. High optical coupling efficiency is obtained in both wavelength ranges, demonstrating the use of the corrugated structure for two-color detection. By monitoring the ratio of the photocurrent generated simultaneously in each MQW stack, the temperature of the object emitting the radiation can be determined, regardless of its emissivity and the geometrical factors. This temperature sensing ability is tested by using a blackbody radiator with precision temperature control as the target. The agreement between the measured and the preset temperatures indicates that the corrugated QWIP is capable of precision thermometric measurements. {copyright} {ital 1998 American Institute of Physics.}

Chen, C.J.; Choi, K.K.; Chang, W.H.; Tsui, D.C. [Department of Electrical Engineering, Princeton University, Princeton, New Jersey 08544 (United States)] [Department of Electrical Engineering, Princeton University, Princeton, New Jersey 08544 (United States)

1998-01-01

301

Polarized Raman spectroscopy of corrugated MBE grown GaAs (6¯3¯1¯) homoepitaxial films  

NASA Astrophysics Data System (ADS)

In this work, we present a Raman scattering study of GaAs layers grown on (6¯3¯1¯)-oriented substrates by molecular beam epitaxy. A set of samples whose morphology sustained different corrugation order were grown by MBE by varying the growth parameters such as temperature and As/Ga flux ratio. We employed polarized Raman spectroscopy using the backscattering configurations Z(XX) Z¯, Z(XY) Z¯ and Z(YY)Z¯. According to the calculated dipole selection rules both TO and LO phonons are allowed for backscattering from a perfect GaAs (6¯3¯1¯) crystal, but with the intensity of the TO phonon much larger than that of the LO phonon. However, it is found that the selection rules differ for corrugated samples. Besides, the TO/LO phonon resonances intensity ratio and the LO peak asymmetry depend on the corrugation order of the samples.

Espinosa-Vega, L. I.; Rodriguez, A. G.; Cruz-Hernandez, E.; Martinez-Veliz, I.; Rojas-Ramirez, J.; Ramirez-Lopez, M.; Nieto-Navarro, J.; Lopez-Lopez, M.; Mendez-Garcia, V. H.

2013-09-01

302

Spatial stereoresolution for depth corrugations may be set in primary visual cortex.  

PubMed

Stereo "3D" depth perception requires the visual system to extract binocular disparities between the two eyes' images. Several current models of this process, based on the known physiology of primary visual cortex (V1), do this by computing a piecewise-frontoparallel local cross-correlation between the left and right eye's images. The size of the "window" within which detectors examine the local cross-correlation corresponds to the receptive field size of V1 neurons. This basic model has successfully captured many aspects of human depth perception. In particular, it accounts for the low human stereoresolution for sinusoidal depth corrugations, suggesting that the limit on stereoresolution may be set in primary visual cortex. An important feature of the model, reflecting a key property of V1 neurons, is that the initial disparity encoding is performed by detectors tuned to locally uniform patches of disparity. Such detectors respond better to square-wave depth corrugations, since these are locally flat, than to sinusoidal corrugations which are slanted almost everywhere. Consequently, for any given window size, current models predict better performance for square-wave disparity corrugations than for sine-wave corrugations at high amplitudes. We have recently shown that this prediction is not borne out: humans perform no better with square-wave than with sine-wave corrugations, even at high amplitudes. The failure of this prediction raised the question of whether stereoresolution may actually be set at later stages of cortical processing, perhaps involving neurons tuned to disparity slant or curvature. Here we extend the local cross-correlation model to include existing physiological and psychophysical evidence indicating that larger disparities are detected by neurons with larger receptive fields (a size/disparity correlation). We show that this simple modification succeeds in reconciling the model with human results, confirming that stereoresolution for disparity gratings may indeed be limited by the size of receptive fields in primary visual cortex. PMID:21876667

Allenmark, Fredrik; Read, Jenny C A

2011-08-01

303

Structural efficiency studies of corrugated compression panels with curved caps and beaded webs  

NASA Technical Reports Server (NTRS)

Curved cross-sectional elements are employed in structural concepts for minimum-mass compression panels. Corrugated panel concepts with curved caps and beaded webs are optimized by using a nonlinear mathematical programming procedure and a rigorous buckling analysis. These panel geometries are shown to have superior structural efficiencies compared with known concepts published in the literature. Fabrication of these efficient corrugation concepts became possible by advances made in the art of superplastically forming of metals. Results of the mass optimization studies of the concepts are presented as structural efficiency charts for axial compression.

Davis, R. C.; Mills, C. T.; Prabhakaran, R.; Jackson, L. R.

1984-01-01

304

Nonlinear finite-difference time-domain modeling of linear and nonlinear corrugated waveguides  

SciTech Connect

A multidimensional, nonlinear finite-difference time-domain (NL-FDTD) simulator, which is constructed from a self-consistent solution of the full-wave vector Maxwell equations and dispersive (Lorentz), nonlinear (finite-time-response Raman and instantaneous Kerr) materials models, is used to study finite-length, corrugated, optical waveguide output couplers and beam steerers. Multiple-cycle, ultrashort-optical-pulse interactions with these corrugated, nonlinear, dispersive waveguides are characterized. An all-optical nonlinear beam-steering device is designed, and its output-coupling performance is characterized with this NL-FDTD simulator.

Ziolkowski, R.W.; Judkins, J.B. (Electromagnetics Laboratory, Department of Electrical and Computer Engineering, The University of Arizona, Tucson, Arizona 85721 (United States))

1994-09-01

305

Turbulent heat transfer enhancement in a heat exchanger using helically corrugated tube  

Microsoft Academic Search

The augmentation of convective heat transfer in a single-phase turbulent flow by using helically corrugated tubes has been experimentally investigated. Effects of pitch-to-diameter ratio (P\\/DH=0.18, 0.22 and 0.27) and rib-height to diameter ratio (e\\/DH=0.02, 0.04 and 0.06) of helically corrugated tubes on the heat transfer enhancement, isothermal friction and thermal performance factor in a concentric tube heat exchanger are examined.

S. Pethkool; S. Eiamsa-ard; S. Kwankaomeng; P. Promvonge

2011-01-01

306

The difference of the transport properties of graphene with corrugation structure and with flat structure  

NASA Astrophysics Data System (ADS)

The transport properties of devices made from graphene ribbons with either perfectly flat or corrugated structures and sandwiched between metallic electrodes are investigated with first principles method. The relaxed geometry of the devices is obtained by using molecular dynamics based on the Tersoff's potential, while the transport is evaluated with a combination of density functional theory and the nonequilibrium Green's function method. In general, the transport properties of the two graphene structures differ from each other. In particular, we find that corrugation greatly enhances the conductance through the device.

Li, G. Q.; Cai, J.; Deng, J. K.; Rocha, A. R.; Sanvito, S.

2008-04-01

307

Squeezed-light generation in a nonlinear planar waveguide with a periodic corrugation  

SciTech Connect

Two-mode nonlinear interaction (second-harmonic and second-subharmonic generation) in a planar waveguide with a small periodic corrugation at the surface is studied. Scattering of the interacting fields on the corrugation leads to constructive interference that enhances the nonlinear process provided that all the interactions are phase matched. Conditions for the overall phase matching are found. Compared with a perfectly quasi-phase-matched waveguide, better values of squeezing as well as higher intensities are reached under these conditions. Procedure for finding optimum values of parameters for squeezed-light generation is described.

Perina, Jan Jr.; Haderka, Ondrej; Sibilia, Concita; Bertolotti, Mario; Scalora, Michael [Joint Laboratory of Optics of Palacky University and Institute of Physics of Academy of Sciences of the Czech Republic, 17. listopadu 50A, 772 07 Olomouc (Czech Republic); Dipartimento di Energetica, Universita 'La Sapienza' di Roma, Via A. Scarpa 16, 00161 Rome (Italy); Charles M. Bowden Research Center, RD and EC, Redstone Arsenal, Bldg 7804, Alabama 35898-5000 (United States)

2007-09-15

308

Comparison of heat transfer in straight and corrugated minichannels with two-phase flow  

NASA Astrophysics Data System (ADS)

Measurements of heat transfer rates performed with an experimental condensation heat exchanger are reported for a corrugated minichannel tube and for a straight minichannel tube. The two cases were compared at same flow regimes. The corrugation appears advantageous for relatively low steam pressures and flow rates where much higher heat transfer rates were observed close to the steam entrance, thus allowing shortening the heat exchanger with the associated advantages of costs lowering and smaller built-up space. At high steam pressures and high flow rates both tubes performed similarly.

Peukert, P.; Hrubý, J.

2014-03-01

309

Corrugation-induced metal-semiconductor transition in single-wall carbon nanotubes with a small radius  

NASA Astrophysics Data System (ADS)

Armchair single-wall carbon nanotubes (SWCNTs) are theoretically predicted to be metallic in the simple zone-folding scheme and protected from the curvature effects. They are, however, found to be small-gap semiconductors, experimentally. Lacking the genuine band-gap opening mechanism for armchair SWCNTs, the Mott insulator concept was proposed previously for the nominally metallic carbon nanotubes. Using the ab initio local density approximation method, we show, in this paper, that the carbon nanotubes without corrugation are, in fact, not metastable. The corrugated structures are always lower in energy than those without corrugation. The size of corrugation increases rapidly with the nanotubes’ curvature and vanishes for flat graphene. The corrugation breaks the local symmetry between two types of carbon sites, and a true band gap starts to develop once graphene sheets are rolled up into nanotubes.

Lu, Hongxia; Wu, Jianbao; Zhang, Weiyi

2013-07-01

310

Gas pipe explorer robot  

NASA Technical Reports Server (NTRS)

A gas pipe explorer formed of a plurality of connecting elements, and an articulation element between the connected elements. The connected elements include drive capabilities, and the articulation element allows the connected elements to traverse gas pipes of arbitrary shapes and sizes. A sensor may sends the characteristics of the gas pipe, and the communication element may send back those sends characteristics. The communication can be wired, over a tether connecting the device to a remote end. Alternatively, the connection can be wireless, driven by either a generator or a battery.

Wilcox, Brian (Inventor)

2004-01-01

311

Automated Ultrasonic Pipe Weld Inspection  

Microsoft Academic Search

Summary This article contains an overview on automated ultrasonic w eld inspection for various pipe types. Some inspection steps might by carried out with portable t est equipment (e.g. pipe end test), but the weld inspection in all internationally relevant specif ications must be automated. The pipe geometry, the production process, and the further pipe usage determine if ND T

Wolfram A. Karl; Peter SCHULTE; Michael JOSWIG; Rainer KATTWINKEL

312

Flexible ultrasonic pipe inspection apparatus  

DOEpatents

Pipe crawlers, pipe inspection {open_quotes}rabbits{close_quotes} and similar vehicles are widely used for inspecting the interior surfaces of piping systems, storage tanks and process vessels for damaged or flawed structural features. This paper describes the design of a flexible, modular ultrasonic pipe inspection apparatus.

Jenkins, C.F.; Howard, B.D.

1994-01-01

313

Experimenting with a "Pipe" Whistle  

ERIC Educational Resources Information Center

A simple pipe whistle can be made using pieces of PVC pipe. The whistle can be used to measure the resonant frequencies of open or closed pipes. A slightly modified version of the device can be used to also investigate the interesting dependence of the sound frequencies produced on the orifice-to-edge distance. The pipe whistle described here…

Stafford, Olga

2012-01-01

314

Improved Thin, Flexible Heat Pipes  

NASA Technical Reports Server (NTRS)

Flexible heat pipes of an improved type are fabricated as layers of different materials laminated together into vacuum- tight sheets or tapes. In comparison with prior flexible heat pipes, these flexible heat pipes are less susceptible to leakage. Other advantages of these flexible heat pipes, relative to prior flexible heat pipes, include high reliability and greater ease and lower cost of fabrication. Because these heat pipes are very thin, they are highly flexible. When coated on outside surfaces with adhesives, these flexible heat pipes can be applied, like common adhesive tapes, to the surfaces of heat sinks and objects to be cooled, even if those surfaces are curved.

Rosenfeld, John H.; Gernert, Nelson J.; Sarraf, David B.; Wollen, Peter J.; Surina, Frank C.; Fale, John E.

2004-01-01

315

An electrohydrodynamic heat pipe  

NASA Technical Reports Server (NTRS)

Dielectric liquid for transfer of heat provides liquid flow from the condenser section to the evaporator section in conventional heat pipes. Working fluid is guided or pumped by an array of wire electrodes connected to a high-voltage source.

Jones, T. B.

1972-01-01

316

Ceramic heat pipe development  

NASA Astrophysics Data System (ADS)

Ceramic materials used in conventional brickwork heat exchanger configurations increase allowable temperatures; however, joint leakage problems limit use of these designs. Ceramic tube heat exchanger designs reduce these problems but still require sliding joints and compliant tube end seals. Ceramic heat pipe based recuperator designs eliminate the sealing problems that limited the high temperature heat recovery installations. Heat pipe recuperators offer high corrosion and abrasion resistance, high temperature capability, reduced leakage, element redundancy, and simplified replacement and cleaning. The development of ceramic heat pipe recuperator elements involves the selection and test of materials and fabrication techniques having production potential, evaluation of technology in subscale tests, design and test of components for full scale recuperator applications, and demonstration of heat pipes in subscale and full scale recuperator installation.

Merrigan, M.

1980-09-01

317

Heat pipe manufacturing study  

NASA Technical Reports Server (NTRS)

Heat pipe manufacturing methods are examined with the goal of establishing cost effective procedures that will ultimately result in cheaper more reliable heat pipes. Those methods which are commonly used by all heat pipe manufacturers have been considered, including: (1) envelope and wick cleaning, (2) end closure and welding, (3) mechanical verification, (4) evacuation and charging, (5) working fluid purity, and (6) charge tube pinch off. The study is limited to moderate temperature aluminum and stainless steel heat pipes with ammonia, Freon-21 and methanol working fluids. Review and evaluation of available manufacturers techniques and procedures together with the results of specific manufacturing oriented tests have yielded a set of recommended cost-effective specifications which can be used by all manufacturers.

Edelstein, F.

1974-01-01

318

Heat pipe development  

NASA Technical Reports Server (NTRS)

The objective of this program was to investigate analytically and experimentally the performance of heat pipes with composite wicks--specifically, those having pedestal arteries and screwthread circumferential grooves. An analytical model was developed to describe the effects of screwthreads and screen secondary wicks on the transport capability of the artery. The model describes the hydrodynamics of the circumferential flow in triangular grooves with azimuthally varying capillary menisci and liquid cross-sections. Normalized results were obtained which give the influence of evaporator heat flux on the axial heat transport capability of the arterial wick. In order to evaluate the priming behavior of composite wicks under actual load conditions, an 'inverted' glass heat pipe was designed and constructed. The results obtained from the analysis and from the tests with the glass heat pipe were applied to the OAO-C Level 5 heat pipe, and an improved correlation between predicted and measured evaporator and transport performance were obtained.

Bienart, W. B.

1973-01-01

319

Impregnation of Concrete Pipe.  

National Technical Information Service (NTIS)

The program was undertaken to investigate methods to increase the corrosion resistance, increase the strength, and reduce the permeability of concrete used in sewer line applications by impregnating the concrete pipe with relatively low cost resins such a...

1971-01-01

320

Heat Pipe Systems  

NASA Technical Reports Server (NTRS)

The heat pipe was developed to alternately cool and heat without using energy or any moving parts. It enables non-rotating spacecraft to maintain a constant temperature when the surface exposed to the Sun is excessively hot and the non Sun-facing side is very cold. Several organizations, such as Tropic-Kool Engineering Corporation, joined NASA in a subsequent program to refine and commercialize the technology. Heat pipes have been installed in fast food restaurants in areas where humid conditions cause materials to deteriorate quickly. Moisture removal was increased by 30 percent in a Clearwater, FL Burger King after heat pipes were installed. Relative humidity and power consumption were also reduced significantly. Similar results were recorded by Taco Bell, which now specifies heat pipe systems in new restaurants in the Southeast.

1993-01-01

321

Silicon Heat Pipe Array  

NASA Technical Reports Server (NTRS)

Improved methods of heat dissipation are required for modern, high-power density electronic systems. As increased functionality is progressively compacted into decreasing volumes, this need will be exacerbated. High-performance chip power is predicted to increase monotonically and rapidly with time. Systems utilizing these chips are currently reliant upon decades of old cooling technology. Heat pipes offer a solution to this problem. Heat pipes are passive, self-contained, two-phase heat dissipation devices. Heat conducted into the device through a wick structure converts the working fluid into a vapor, which then releases the heat via condensation after being transported away from the heat source. Heat pipes have high thermal conductivities, are inexpensive, and have been utilized in previous space missions. However, the cylindrical geometry of commercial heat pipes is a poor fit to the planar geometries of microelectronic assemblies, the copper that commercial heat pipes are typically constructed of is a poor CTE (coefficient of thermal expansion) match to the semiconductor die utilized in these assemblies, and the functionality and reliability of heat pipes in general is strongly dependent on the orientation of the assembly with respect to the gravity vector. What is needed is a planar, semiconductor-based heat pipe array that can be used for cooling of generic MCM (multichip module) assemblies that can also function in all orientations. Such a structure would not only have applications in the cooling of space electronics, but would have commercial applications as well (e.g. cooling of microprocessors and high-power laser diodes). This technology is an improvement over existing heat pipe designs due to the finer porosity of the wick, which enhances capillary pumping pressure, resulting in greater effective thermal conductivity and performance in any orientation with respect to the gravity vector. In addition, it is constructed of silicon, and thus is better suited for the cooling of semiconductor devices.

Yee, Karl Y.; Ganapathi, Gani B.; Sunada, Eric T.; Bae, Youngsam; Miller, Jennifer R.; Beinsford, Daniel F.

2013-01-01

322

Freezable heat pipe  

DOEpatents

A heat pipe whose fluid can be repeatedly frozen and thawed without damage to the casing. An additional part is added to a conventional heat pipe. This addition is a simple porous structure, such as a cylinder, self-supporting and free standing, which is dimensioned with its diameter not spanning the inside transverse dimension of the casing, and with its length surpassing the depth of maximum liquid.

Ernst, Donald M. (Leola, PA); Sanzi, James L. (Lancaster, PA)

1981-02-03

323

Measurement of Amplitude and Phase Patterns of 110 GHz and 183 GHz Corrugated Horns.  

National Technical Information Service (NTIS)

Radiation patterns (amplitude and phase) of two corrugated feed horns designed for a 2 m single offset reflector antenna have been measured. The measured amplitude and phase patterns can be used to calculate the far-field radiation patterns and finally th...

A. Lehto J. Tuovinen A. Raeisaenen

1990-01-01

324

Corrugated elliptical horn antennas for the generation of radiation patterns with elliptical cross-section  

Microsoft Academic Search

This thesis is concerned with the evaluation of the electrical performance of an antenna system which consists of a single offset parabolic reflector fed by a corrugated elliptical horn radiator. Such an antenna system can be designed in such a way that it becomes suitable for an employment as the transmitting antenna of a broadcasting satellite. One objective of this

S. C. J. Worm

1985-01-01

325

Application of the method of integral equations to calculate the electrodynamic characteristics of periodically corrugated waveguides  

Microsoft Academic Search

A method for calculating the electrodynamic characteristics of periodically corrugated waveguides is described which is based on the representation of the field as a solution of the Helmoltz vector equation in the form of a simple-layer potential, transformed using the Floquet conditions. Systems of mixed integral equations for the weight vector function of the simple-layer potential in azimuthally symmetric and

V. E. Belov; L. V. Rodygin; S. E. Fil'Chenkov; A. D. Iunakovskii

1988-01-01

326

Helically corrugated waveguide gyrotron traveling wave amplifier using a thermionic cathode electron gun  

Microsoft Academic Search

Experimental operation of a gyrotron traveling wave amplifier with a helically corrugated waveguide using a thermionic cathode electron gun is presented. The coupling between the second harmonic cyclotron mode of the gyrating electron beam and the radiation occurred in the region of near infinite phase velocity over a broad frequency band. With an axis-encircling electron beam of pitch factor of

A. W. Cross; W. He; A. D. R. Phelps; K. Ronald; C. G. Whyte; A. R. Young; C. W. Robertson; E. G. Rafferty; J. Thomson

2007-01-01

327

TE(01) mode propagation at wavelength = 394 microns in smooth and corrugated circular metallic waveguides  

Microsoft Academic Search

The attenuation of the TE(01) mode in straight circular metallic waveguides has been measured at wavelength = 394 microns. The radiation was produced by an optically-pumped HCOOH waveguide laser, with i.d. as small as 4 mm. The losses were measured in smooth waveguides as well as in guides with a fine helical corrugation on the inner wall, designed to reduce

M. E. Marhic; D. Spektor

1983-01-01

328

A W-band Gyro-BWO based on a Helically Corrugated Waveguide  

Microsoft Academic Search

This paper presents the theoretical results of a CW W-band (88-102 GHz), 10 kW gyrotron backward-wave oscillator (gyro-BWO). A mildly relativistic, axis-encircling electron beam from a cusp gun has been designed to drive an interaction based on the cyclotron resonance maser (CRM) instability in a cavity with a helically corrugated inner surface.

W. He; C. R. Donaldson; A. D. R. Phelps; A. W. Cross; K. Ronald

2006-01-01

329

Analysis of coiled-tube heat exchangers to improve heat transfer rate with spirally corrugated wall  

Microsoft Academic Search

Steady heat transfer enhancement has been studied in helically coiled-tube heat exchangers. The outer side of the wall of the heat exchanger contains a helical corrugation which makes a helical rib on the inner side of the tube wall to induce additional swirling motion of fluid particles. Numerical calculations have been carried out to examine different geometrical parameters and the

A. Zachár

2010-01-01

330

Calculation of Dispersion Characteristics of a Circular Waveguide with Deep Helical Corrugation by the FDTD Method  

Microsoft Academic Search

We study the dispersion characteristics of a circular waveguide with helical corrugation, which are used in microwave amplifiers and oscillators. The results of calculations by the finite difference time domain (FDTD) method are compared with the results obtained using the perturbation theory and the experimental results. The problems of improving the calculation accuracy are considered

M. L. Kulygin

2004-01-01

331

Dispersion Analysis of helical corrugation waveguide for Gyro-TWT and Gyro-BWO  

Microsoft Academic Search

The paper puts forward a simple method of solving the coupled coefficient and the dispersion equation of the backward wave in the helical corrugation waveguide gyro-BWO. And using the VBA macro in the software CST, two taper parts and a regular part helical waveguide is founded. A simulation method is used to analysis the dispersion curve.

Lei Wen-qiang; Yang Zhong-Hai; Li Ming

2006-01-01

332

High-Gain Wide-Band Gyrotron Traveling Wave Amplifier with a Helically Corrugated Waveguide  

Microsoft Academic Search

First bandwidth measurements of a novel gyrotron amplifier are presented. The coupling between the second harmonic cyclotron mode of a gyrating electron beam and the radiation field occurred in the region of near infinite phase velocity over a broad bandwidth by using a cylindrical waveguide with a helical corrugation on its internal surface. With a beam energy of 185 keV,

V. L. Bratman; A. W. Cross; G. G. Denisov; W. He; A. D. R. Phelps; K. Ronald; S. V. Samsonov; C. G. Whyte; A. R. Young

2000-01-01

333

Compression of pulses from a relativistic bwo using helically corrugated waveguides  

Microsoft Academic Search

The use of an overmoded circular waveguide with helical corrugations (HC) of its inner surface as a dispersive medium enables compression of monotonously frequency modulated microwave pulses. The region of operating parameters (frequency range, input pulse duration, sweep interval) in conjunction with low reflection and high RF electric strength makes the HC-waveguide compressor attractive for increasing the peak power from

V. L. Bratman; S. V. Samsonov; S. V. Mishakin; G. G. Denisov; N. G. Kolganov; M. McStravick; A. W. Cross; W. He; C. W. Robertson; C. G. Whyte; A. R. Young; K. Ronald; A. D. R. Phelps; P. Maclnnes

2009-01-01

334

On the Wave Propagation and Mode Conversion in a Helically Corrugated Multimode Circular Waveguide  

Microsoft Academic Search

For specific forms of excitations, the normal modes and mode coefficients of a lossless helically corrugated circular multimode waveguide are determined from the appropriate boundary conditions. Because of the multiplicity of the roots of the characteristic dispersion equation obtained, care must be exercised in the evaluation of the equation and in the interpretation of the ?-? diagram. For the TE11

C. C. H. Tang

1966-01-01

335

Experimental investigation on phase constant and cutoff wavelength of a cocoon-section corrugated waveguide  

Microsoft Academic Search

The paper deals with an experimental investigation of the phase constant and cut-off wavelength of a waveguide, whose cross section is shaped as a cocoon and whose side walls exhibit a sinusoidal helical corrugation along the longitudinal axis. The waveguide is well suited for use as an antenna feeder waveguide in 4-, 5-, 6-, and 7-GHz band microwave communications systems.

K. Abe; A. Hashimoto

1979-01-01

336

Efficient computation of three-dimensional flow in helically corrugated hoses including swirl  

Microsoft Academic Search

In this article we propose an ecient method to compute the friction factor of helically corrugated hoses carrying flow at high Reynolds numbers. A comparison between computations of sev- eral turbulence models is made with experimental results for cor- rugation sizes that fall outside the range of validity of the Moody diagram. To do this eciently we implement quasi-periodicity. Using

Bas J. van der Linden; M Pisarenco; Jacques Dam; Arris S. Tijsseling

2009-01-01

337

Resonant Enhancement of Radiation from a Backward Wave Oscillator Utilizing Large Diameter Corrugated Metal Structure  

Microsoft Academic Search

An experiment on a backward wave oscillator (BWO) utilizing a largediameter corrugated metal wall slow wave structure (SWS) has beenpresented. Measurements are made above and below the starting beamenergy for conventional BWO operation. For the latter case, an excitednoise-level backward wave at 20 GHz (TM01 mode) is coupled at theends of the SWS to a forward anomalous Doppler shifted electroncyclotron

Kazuo Minami; Kazuo Ogura; Xiaodong Zheng; Tsuguhiro Watanabe

1995-01-01

338

Novel partially corrugated waveguide laser diode with low modulation distortion characteristics for subcarrier multiplexing  

NASA Astrophysics Data System (ADS)

A novel partially corrugated waveguide laser diode (PC-LD) for subcarrier multiplexing was proposed. High yield characteristics for low distortion specification (IMD(sub 3) less than EQ - 80dBc) were demonstrated theoretically and experimentally. This is attributed to the electric field uniformity improvement along the cavity and the grating facet phase insensitivity in the PC-LD.

Okuda, T.; Yamada, H.; Torikai, T.; Uji, T.

1994-05-01

339

Survey of recent work on the analysis of discretely attached corrugated shear webs.  

NASA Technical Reports Server (NTRS)

Summary and progress report of more recent work by the author and his students on the theoretical analysis of stiffness, stresses, and deformations of corrugated shear webs with discrete, rather than continuous, attachment between the ends of the corrugations and the surrounding members. Various kinds of discrete attachment are considered, and two kinds of corrugation cross section: the trapezoidal and the curvilinear, the latter having crests and valleys made up of identical circular arcs. The more recent analyses employ the method of minimum total potential energy and the calculus of variations to obtain differential equations and boundary conditions governing the longitudinal variation of various component modes used to describe the deformations of a cross section. They are believed to be more accurate than earlier analyses in that they generally permit more degrees of freedom in the assumed deformations. In particular, they abandon the assumption, characteristic of the earlier analyses, that the straight-line generators of the corrugation remain straight during the shearing of the web.

Libove, C.

1972-01-01

340

A numerical and experimental study of chevron, corrugated-plate heat exchangers  

Microsoft Academic Search

In this work, the widely used chevron corrugated-plate heat exchanger was simulated, and the three-dimensional temperature, pressure, and velocity fields were obtained. From the temperature field we can see that in the first zone, the temperature gradient increases gradually and get the maximum; in the central of the flow, the temperature gradient becomes smaller again. The highest temperature appears around

Xiao-Hong Han; Li-Qi Cui; Shao-Jie Chen; Guang-Ming Chen; Qin Wang

2010-01-01

341

Corrugated waveguide slow-wave structure for THz travelling wave tube  

Microsoft Academic Search

THz applications require sources and amplifiers compact, lightweight and powerful. Vacuum electron devices are the candidate solution. Among others, the corrugated waveguide slow-wave structure seems particularly suitable for traveling wave tubes in the THz region. THz vacuum electron devices require high precision technological processes with high aspect ratio such as SU-8 process. However, fabrication tolerances could highly affect the overall

Mauro Mineo; Claudio Paoloni; Aldo Di Carlo; Anna Maria Fiorello; Massimiliano Dispenza

2009-01-01

342

Scattering of Te and Tm Electromagnetic Waves From a Corrugated Cylinder  

Microsoft Academic Search

We show how integral equations can be used to solve boundary value problems of the scalar Helmholtz equation with Dirichlet and Neumann boundary data supplied on a circular cylinder. An application is given to the scattering of a TM electromagnetic wave on a corrugated perfectly conducting cylinder. We discuss when these integral equations can be used.

P. Hillion

2000-01-01

343

Fabrication and test of a thermopneumatic micropump with a corrugated p+ diaphragm  

Microsoft Academic Search

This paper presents a thermopneumatic micropump fabricated by micromachining. The micropump consists of a p+ silicon diaphragm, a micro heater and a pair of nozzle\\/diffuser. The thermopneumatic actuator of this paper is characterized by a corrugated diaphragm, which is more flexible than a flat one. The diaphragm is driven by the air cavity pressure variation caused by the ohmic heating

Ok Chan Jeong; Sang Sik Yang

2000-01-01

344

Nano-Optical Control of Hot-Spot Field Superenhancement on a Corrugated Silver Surface  

Microsoft Academic Search

Coherent control of ultrafast nano-optical excitations of a corrugated silver surface is demonstrated by means of predetermined few-parameter scans and adaptive polarization laser pulse shaping. “Hot spots” in the multiphoton photoemission signals are enhanced and manipulated with a high contrast. Switching between separated and closely spaced hot spots is shown. The latter allows controlling the shape of hot spots and

Martin Aeschlimann; Tobias Brixner; Stefan Cunovic; Alexander Fischer; Pascal Melchior; Walter Pfeiffer; Martin Rohmer; Christian Schneider; Christian Strüber; Philip Tuchscherer; Dmitri V. Voronine

2012-01-01

345

Shear band blocking in explosively driven collapse of corrugated Ni-Al laminate cylinder  

NASA Astrophysics Data System (ADS)

Ni-Al laminate materials have been identified as a possible material system that can be used as a reactive material due to the self-sustaining reaction between Al and Ni layers. Besides traditional ignition methods, shear bands developed during mechanical loading can provide sites where ignition can occur. Corrugated Ni-Al laminate samples were created by swaging alternating layers of Ni (20 micrometers thick) and Al (30 micrometers thick) foils. The thick-walled cylinder (TWC) technique was performed on a corrugated Ni-Al laminate cylinder sample to examine shear band development in this material. Post experiment examination of the corrugated Ni-Al laminate material showed that the development of global shear bands were blocked via mesoscale mechanisms. The collapse of the corrugated laminate cylinder was simulated providing insight into these mesoscale mechanisms that were involved in blocking the development of shear bands during the experiment. Despite the shear band resistance of the material, several regions of the sample had localized reactions of Al and Ni spanning approximately 10-20 layers of laminate.

Olney, Karl; Chiu, Po-Hsun; Higgins, Andrew; Serge, Matthew; Fritz, Gregory; Stover, Adam; Nesterenko, Vitali; Benson, David

2013-03-01

346

Conductor load bearing roller for a gas-insulated transmission line having a corrugated outer conductor  

DOEpatents

A gas-insulated transmission line includes a corrugated outer conductor, an inner conductor disposed within and insulated from the outer conductor by means of support insulators and an insulating gas, and a transport device for supporting and permitting movement of the inner conductor/insulating support assembly axially along the corrugated outer conductor without radial displacement. The transport device includes two movable contacts, such as skids or rollers, supported on a common pivot lever, the pivot lever being rotatably disposed about a pivot lever axis, which pivot lever axis is in turn disposed on the periphery of a support insulator or particle trap if one is used. The movable contacts are separated axially a distance equal to the axial distance between the peaks and valleys of the corrugations of the outer conductor and separated radially a distance equal to the radial distance between the peaks and valleys of the corrugations of the outer conductor. The transport device has the pivot lever axis disposed perpendicular to the direction of travel of the inner conductor/insulating support assembly.

Fischer, William H. (Pittsburgh, PA); Yoon, Kue H. (Pittsburgh, PA)

1984-04-10

347

Method for producing ultrafine-grained materials using repetitive corrugation and straightening  

DOEpatents

A method of refining the grain structure and improving the hardness and strength properties of a metal or metal alloy workpiece is disclosed. The workpiece is subjected to forces that corrugate and then straighten the workpiece. These steps are repeated until an ultrafine-grained product having improved hardness and strength is produced.

Zhu, Yuntian T. (Los Alamos, NM) [Los Alamos, NM; Lowe, Terry C. (Santa Fe, NM) [Santa Fe, NM; Jiang, Honggang (Los Alamos, NM) [Los Alamos, NM; Huang, Jianyu (Los Alamos, NM) [Los Alamos, NM

2001-01-01

348

Pressure and heating-rate distributions on a corrugated surface in a supersonic turbulent boundary layer  

NASA Technical Reports Server (NTRS)

Drag and heating rates on wavy surfaces typical of current corrugated plate designs for thermal protection systems were determined experimentally. Pressure-distribution, heating-rate, and oil-flow tests were conducted in the Langley Unitary Plan wind tunnel at Mach numbers of 2.4 and 4.5 with the corrugated surface exposed to both thick and thin turbulent boundary layers. Tests were conducted with the corrugations at cross-flow angles from 0 deg to 90 deg to the flow. Results show that for cross-flow angles of 30 deg or less, the pressure drag coefficients are less than the local flat-plate skin-friction coefficients and are not significantly affected by Mach number, Reynolds number, or boundary-layer thickness over the ranges investigated. For cross-flow angles greater than 30 deg, the drag coefficients increase significantly with cross-flow angle and moderately with Reynolds number. Increasing the Mach number causes a significant reduction in the pressure drag. The average and peak heating penalties due to the corrugated surface are small for cross-flow angles of 10 deg or less but are significantly higher for the larger cross-flow angles.

Sawyer, J. W.

1977-01-01

349

Theoretical Analysis of Axial Crushing of Cylindrical Tubes with Corrugated Surfaces  

Microsoft Academic Search

A new theoretical model of axial crushing of cylindrical tubes with corrugated surfaces has been developed in which the crushing force is analyzed by considering the equilibrium of work done by the crushing force and the energy required to deform the tube. The energy absorbed by the cylindrical tube being crushed is taken to be the sum of the bending

Dai-Heng Chen; Shingo Ozaki

2009-01-01

350

Corrugated quantum well infrared photodetectors with polyimide planarization for detector array applications  

Microsoft Academic Search

Recently, we have demonstrated a new light coupling scheme for quantum well infrared photodetectors (QWIP). The new detector structure, referred to as corrugated QWIP (C-QWIP), is created by chemically etching linear V-grooves through the detector active region. In this structure, normal incident light is directed into the detector active region through total internal reflection, with which the optical absorption of

Chen-Jung Chen; Kwong-Kit Choi; Wayne H. Chang; Daniel C. Tsui

1998-01-01

351

The effect of lateral creepage force on rail corrugation on low rail at sharp curves  

Microsoft Academic Search

In Japanese narrow gauge lines, short pitch corrugations on low rail at sharp curved track whose radius of curvature is less than 600m pose very large problems that are noise and track deterioration caused by large vibration excited with interacting forces between rail and wheel. This paper describes the lateral force has great influence on the formation of short pitch

M Ishida; T Moto; M Takikawa

2002-01-01

352

Dimensional analysis for the heat transfer characteristics in the corrugated channels of plate heat exchangers  

Microsoft Academic Search

Using the Buckingham Pi theorem, this study derives dimensionless correlations to characterize the heat transfer performance of the corrugated channel in a plate heat exchanger. The experimental data are substituted into these correlations to identify the flow characteristics and channel geometry parameters with the most significant influence on the heat transfer performance. Simplified correlations by omitting the factors with less

J. H. Lin; C. Y. Huang; C. C. Su

2007-01-01

353

Effect of absorption on terahertz surface plasmon polaritons propagating along periodically corrugated metal wires  

Microsoft Academic Search

In this paper, a rigorous method for analyzing surface plasmon polaritons (SPPs) on a periodically corrugated metal wire has been formulated, based on a modal expansion of electromagnetic fields. Compared with the previous method, our method takes into account the finite conductivity of the wire as well as higher-order modes within the wire grooves in the expansion, thus is able

Linfang Shen; Xudong Chen; Yu Zhong; Krishna Agarwal

2008-01-01

354

Terahertz Surface Plasmon-Polariton Propagation and Focusing on Periodically Corrugated Metal Wires  

Microsoft Academic Search

In this Letter, we show how the dispersion relation of surface plasmon polaritons (SPPs) propagating along a perfectly conducting wire can be tailored by corrugating its surface with a periodic array of radial grooves. In this way, highly localized SPPs can be sustained in the terahertz region of the electromagnetic spectrum. Importantly, the propagation characteristics of these spoof SPPs can

Stefan A. Maier; Steve R. Andrews; L. Martín-Moreno; F. J. García-Vidal

2006-01-01

355

Electronic and optical properties of corrugated GaAs/AlAs superlattices  

NASA Astrophysics Data System (ADS)

The tight-binding method is applied to the analysis of the electronic and optical properties of corrugated GaAs/AlAs superlattices recently grown by molecular beam epitaxy on (311) A GaAs oriented substrates. These structures are of great interest because the facetting of the flat surface leads to the formation of quantum wires by a lateral corrugation with period of 3.2 nm. The model uses a sp3s * atomic basis including the spin-orbit coupling and second-neighbor interactions. The Hamiltonian parameters are fitted so as the energy bands of the two semiconductors near the ? and X band edges are accurately described. The unit cell of quantum-wire superlattices is two-dimensional and lead to a very large tight-binding basis containing 320xN local orbitals for a superlattice of N layers along the growth direction [311]. The electronic band structure is calculated in order to investigate the nature of the lowest conduction bands and these features are explained in terms of zone folding and lateral corrugation. For corrugated superlattices with layers of equal widths larger than 3.2 nm, the main contribution to the lowest energy conduction state is due to the cation s orbitals and is identified as coming from the ?-valley of GaAs. For thinner widths, the cation p orbitals of the AlAs layers give the major contribution to the lowest conduction state. This situation is quite similar to the crossing of the ?- and X-like states of (100)-grown superlattices which present a type I-type II transition near 3 nm. Comparison with non-corrugated (311) superlattices with (311) flat faces shows that corrugation increases the confinement of the lowest conduction bands, more localizing the ?-electrons in GaAs wells and the X-electrons in the AlAs barriers. The two upper valence states are localized in GaAs layers. They result from mixing of the bulk states due to the reduced symmetry of the quantum wires and show an appreciate in-plane anisotropy. The calculated value of the ?- and X-like state crossing is in agreement with the experimental observations. Optical properties of (311) corrugated superlattice are studied and the calculated interband transitions account for the photoluminescence data.

Jouanin, Christian; Bertho, Denis

356

Heat Pipe Integrated Microsystems  

SciTech Connect

The trend in commercial electronics packaging to deliver ever smaller component packaging has enabled the development of new highly integrated modules meeting the demands of the next generation nano satellites. At under ten kilograms, these nano satellites will require both a greater density electronics and a melding of satellite structure and function. Better techniques must be developed to remove the subsequent heat generated by the active components required to-meet future computing requirements. Integration of commercially available electronics must be achieved without the increased costs normally associated with current generation multi chip modules. In this paper we present a method of component integration that uses silicon heat pipe technology and advanced flexible laminate circuit board technology to achieve thermal control and satellite structure. The' electronics/heat pipe stack then becomes an integral component of the spacecraft structure. Thermal management on satellites has always been a problem. The shrinking size of electronics and voltage requirements and the accompanying reduction in power dissipation has helped the situation somewhat. Nevertheless, the demands for increased onboard processing power have resulted in an ever increasing power density within the satellite body. With the introduction of nano satellites, small satellites under ten kilograms and under 1000 cubic inches, the area available on which to place hot components for proper heat dissipation has dwindled dramatically. The resulting satellite has become nearly a solid mass of electronics with nowhere to dissipate heat to space. The silicon heat pipe is attached to an aluminum frame using a thermally conductive epoxy or solder preform. The frame serves three purposes. First, the aluminum frame provides a heat conduction path from the edge of the heat pipe to radiators on the surface of the satellite. Secondly, it serves as an attachment point for extended structures attached to the satellite such as solar panels, radiators, antenna and.telescopes (for communications or sensors). Finally, the packages make thermal contact to the surface of the silicon heat pipe through soft thermal pads. Electronic components can be placed on both sides of the flexible circuit interconnect. Silicon heat pipes have a number of advantages over heat pipe constructed from other materials. Silicon heat pipes offer the ability to put the heat pipe structure beneath the active components of a processed silicon wafer. This would be one way of efficiently cooling the heat generated by wafer scale integrated systems. Using this technique, all the functions of a satellite could be reduced to a few silicon wafers. The integration of the heat pipe and the electronics would further reduce the size and weight of the satellite.

Gass, K.; Robertson, P.J.; Shul, R.; Tigges, C.

1999-03-30

357

Reducing stress in contained pipes  

SciTech Connect

Increasingly, chemical-process-industries plants are conveying fluids in contained pipes. These pipes inside pipes improve operational and environmental safety by keeping leaks from escaping into the plant, if the pipes are indoors, or into the soil, air or water if they are outdoors. Du Pont recently installed two contained-piping systems in one of its Wilmington, Del., facilities. The lines are made from fiberglass-reinforced vinyl ester, with 3-in.-dia. carrier pipes and 6-in.-dia. containment pipes. Heat from flowing liquid makes the carrier pipes expand, which causes them to move laterally inside the containment pipe. When flow stops, the temperature drops and the carrier pipes contract. To limit carrier-pipe movement, DuPont planned to install donut-shaped support at the ends of straight-run sections. However, a computerized analysis found that the supports cause high stress in the carrier pipes. The paper describes the solution that Du Pont found to reduce the stress on the piping and prolong the service life of the pipes.

Not Available

1993-07-01

358

Explosive Welding of Pipes  

NASA Astrophysics Data System (ADS)

For connection by welding it is suggested to use the explosive welding method. This method is rather new. Nevertheless, it has become commonly used among the technological developments. This method can be advantageous (saving material and physical resources) comparing to its statical analogs (electron-beam welding, argon-arc welding, plasma welding, gas welding, etc.), in particular, in hard-to-reach areas due to their geographic and climatic conditions. The suggestion is to use water as filler. The principle of non-compressibility of liquid under quasi-dynamic loading is used. In one-dimensional gasdynamic and elastic-plastic calculations we determined non-deformed mass of water (perturbations, which are moving in the axial direction with sound velocity, should not reach the layer end boundaries for 5-7 circulations of shock waves in the radial direction). Linear dimension of the water layer from the zone of pipe coupling along axis in each direction is >= 2R, where R is the internal radius of pipe. Model experiments with pipes having radii R = 57 mm confirmed results of the calculations and the possibility in principle to weld pipes by explosion with use of water as filler. Reduction of pipe diameter after dynamic loading and explosive welding was ˜2%.

Burtseva, Olga

2007-06-01

359

Pipe Clamp Effects on Thin-Walled Pipe Design.  

National Technical Information Service (NTIS)

Clamp induced stresses in FFTF piping are sufficiently large to require structural assessment. The basic principles and procedures used in analyzing FFTF piping at clamp support locations for compliance with ASME Code rules are given. Typical results from...

M. R. Lindquist

1980-01-01

360

Composite drill pipe  

DOEpatents

A composite pipe segment is formed to include tapered in wall thickness ends that are each defined by opposed frustoconical surfaces conformed for self centering receipt and intimate bonding contact within an annular space between corresponding surfaces of a coaxially nested set of metal end pieces. The distal peripheries of the nested end pieces are then welded to each other and the sandwiched and bonded portions are radially pinned. The composite segment may include imbedded conductive leads and the axial end portions of the end pieces are shaped to form a threaded joint with the next pipe assembly that includes a contact ring in one pipe assembly pierced by a pointed contact in the other to connect the corresponding leads across the joint.

Leslie, James C. (Fountain Valley, CA); Leslie, II, James C. (Mission Viejo, CA); Heard, James (Huntington Beach, CA); Truong, Liem (Anaheim, CA), Josephson; Marvin (Huntington Beach, CA), Neubert; Hans (Anaheim, CA)

2008-12-02

361

Heat Pipe Technology  

NASA Technical Reports Server (NTRS)

The heat pipe, a sealed chamber whose walls are lined with a "wick," a thin capillary network containing a working fluid in liquid form was developed for a heat distribution system for non-rotating satellites. Use of the heat pipe provides a continuous heat transfer mechanism. "Heat tubes" that improve temperature control in plastics manufacturing equipment incorporated the heat pipe technology. James M. Stewart, an independent consultant, patented the heat tubes he developed and granted a license to Kona Corporation. The Kona Nozzle for heaterless injection molding gets heat for its operation from an external source and has no internal heating bands, reducing machine maintenance and also eliminating electrical hazards associated with heater bands. The nozzles are used by Eastman Kodak, Bic Pen Corporation, Polaroid, Tupperware, Ford Motor Company, RCA, and Western Electric in the molding of their products.

1981-01-01

362

Heat-pipe Earth.  

PubMed

The heat transport and lithospheric dynamics of early Earth are currently explained by plate tectonic and vertical tectonic models, but these do not offer a global synthesis consistent with the geologic record. Here we use numerical simulations and comparison with the geologic record to explore a heat-pipe model in which volcanism dominates surface heat transport. These simulations indicate that a cold and thick lithosphere developed as a result of frequent volcanic eruptions that advected surface materials downwards. Declining heat sources over time led to an abrupt transition to plate tectonics. Consistent with model predictions, the geologic record shows rapid volcanic resurfacing, contractional deformation, a low geothermal gradient across the bulk of the lithosphere and a rapid decrease in heat-pipe volcanism after initiation of plate tectonics. The heat-pipe Earth model therefore offers a coherent geodynamic framework in which to explore the evolution of our planet before the onset of plate tectonics. PMID:24067709

Moore, William B; Webb, A Alexander G

2013-09-26

363

Apparatus for inspecting piping  

DOEpatents

An inspection rabbit for inspecting piping systems having severe bends therein. The rabbit consists of a flexible, modular body containing a miniaturized eddy current inspection probe, a self-contained power supply for proper operation of the rabbit, an outer surface that allows ease of movement through piping systems and means for transmitting data generated by the inspection device. The body is preferably made of flexible polyvinyl chloride (PVC) tubing or, alternatively, silicone rubber with a shrink wrapping of polytetrafluoroethylene (TEFLON.RTM.). The body is formed to contain the power supply, preferably a plurality of batteries, and a spool of communication wire that connects to a data processing computer external to the piping system.

Zollingger, W. Thor (Martinez, GA); Appel, D. Keith (Aiken, SC); Park, Larry R. (Raleigh, NC)

1995-01-01

364

Apparatus for inspecting piping  

DOEpatents

An inspection rabbit is described for inspecting piping systems having severe bends therein. The rabbit consists of a flexible, modular body containing a miniaturized eddy current inspection probe, a self-contained power supply for proper operation of the rabbit, an outer surface that allows ease of movement through piping systems and means for transmitting data generated by the inspection device. The body is preferably made of flexible polyvinyl chloride (PVC) tubing or, alternatively, silicone rubber with a shrink wrapping of polytetrafluoroethylene (TEFLON{trademark}). The body is formed to contain the power supply, preferably a plurality of batteries, and a spool of communication wire that connects to a data processing computer external to the piping system. 6 figures.

Zollingger, W.T.; Appel, D.K.; Park, L.R.

1995-03-21

365

Heat pipes and use of heat pipes in furnace exhaust  

DOEpatents

An array of a plurality of heat pipe are mounted in spaced relationship to one another with the hot end of the heat pipes in a heated environment, e.g. the exhaust flue of a furnace, and the cold end outside the furnace. Heat conversion equipment is connected to the cold end of the heat pipes.

Polcyn, Adam D. (Pittsburgh, PA) [Pittsburgh, PA

2010-12-28

366

Insituform Pipe Rehabilation, Construction Report.  

National Technical Information Service (NTIS)

The report covers the construction evaluation of a pipe rehabilitation project where INSITUFORM was used. INSITUFORM is a manufacturer's name for a pipe relining process which uses cold water inversion to propel a thermo-setting resin coated polyester fib...

B. Yedinak K. Highlands

1986-01-01

367

Tippy Tap Plus Piping  

NSDL National Science Digital Library

The Tippy Tap hand-washing station is an inexpensive and effective device used extensively in the developing world. One shortcoming of the homemade device is that it must be manually refilled with water and therefore is of limited use in high-traffic areas. In this activity, student teams design, prototype and test piping systems to transport water from a storage tank to an existing Tippy Tap hand-washing station, thereby creating a more efficient hand-washing station. Through this example service-learning engineering project, students learn basic fluid dynamic principles that are needed for creating efficient piping systems.

Integrated Teaching and Learning Program, College of Engineering, University of Colorado at Boulder,

368

Theory of a microwave-pulse compressor based on a barrel-shaped cavity with helical-corrugated surface  

Microsoft Academic Search

The radiation damping ratio and the transmission coefficient were calculated for a passive compressor of microwave pulses\\u000a that is built around a length of an oversized waveguide with a helical-corrugated internal surface.

Yu. Yu. Danilov; S. V. Kuzikov; M. I. Petelin

2000-01-01

369

Fabrication of corrugated curved beam type electrostatic actuator and SDA driven self-assembling mechanism for VOA applications  

Microsoft Academic Search

In this paper, we present an innovative design of corrugated curved beam type electrostatic actuator with continuous motion capability, and SDA (scratch drive actuator) driven self-assembling mechanism for axial type MEMS VOA application.

Yen-Jyh Lai; Chengkuo Lee; Chia-Yu Wu; Yu-Shen Lin; Ming Hung Tasi; Ruey-Shing Huang; Min-Shyong Lin

2003-01-01

370

Analysis of a disk-on-rod surface wave element inside a corrugated horn using the mode-matching technique  

NASA Astrophysics Data System (ADS)

A disk-on-rod inside a corrugated horn is one of the horn configurations for dual-frequency or wide-band operation. A mode-matching analysis method is described. A disk-on-rod inside a corrugated horn is represented as a series of coaxial waveguide sections and circular waveguide sections connected to each other. Three kinds of junctions need to be considered: coaxial-to-coaxial, coaxial-to-circular, and circular-to-circular. A computer program was developed to calculate the scattering matrix and the radiation pattern of a disk-on-rod inside a corrugated horn. The software as verified by experiment, and good agreement between calculation and measurement was obtained. The disk-on-rod inside a corrugated horn design gives an option to the Deep Space Network dual-frequency operation system, which currently is a two-horn/one-dichroic plate system.

Chen, J. C.

1995-02-01

371

Heat Pipe With Interrupted Slot  

NASA Technical Reports Server (NTRS)

Newer version of heat pipe slot interrupted by plug or, if heat pipe is cast, by bridge of heat-pipe material cast integrally across groove. Small barrier assists in priming heat pipe. Vapor and noncondensible gas still accumulates in liquid channel at evaporator before or during startup, but barrier keeps liquid out of small part of slot at bubble. Dry part of slot allows bubble to escape into vapor channel, making room for liquid to move in during startup.

Brown, Richard F.; Kosson, Robert L.; Edelstein, Fred

1994-01-01

372

Long-term aging of fiber-cement corrugated sheets – The effect of carbonation, leaching and acid rain  

Microsoft Academic Search

This paper studies the performance of fiber-cement corrugated sheets exposed to long-term weathering, exploring the effect of different environments on fiber-cement degradation. Fiber-cement corrugated sheets that had been exposed to weathering, and in place for more than 30-years, were collected from two different Brazilian cities (São Paulo and Criciúma). Mechanical properties (MOR, MOE and fracture toughness) were tested on samples

C. M. R. Dias; M. A. Cincotto; H. Savastano Jr; V. M. John

2008-01-01

373

Broadband light extraction from white organic light-emitting devices by employing corrugated metallic electrodes with dual periodicity.  

PubMed

A dual-periodic corrugation consisting of two sets of gratings with different periods to realize a broadband light extraction in white organic light-emitting diodes (WOLEDs) is shown. A 37% enhancement in current efficiency and 48% enhancement in the external quantum efficiency compared to those of the conventional planar devices have been obtained. Besides the much improved efficiency, the dual-periodic corrugated WOLEDs exhibit satisfying viewing characteristics. PMID:24352984

Bi, Yan-Gang; Feng, Jing; Li, Yun-Fei; Zhang, Xu-Lin; Liu, Yue-Feng; Jin, Yu; Sun, Hong-Bo

2013-12-23

374

Microwave pulse compression using helically corrugated waveguides and its potential for generating ultra-high power RF radiation  

Microsoft Academic Search

The use of a helically corrugated waveguide as a dispersive medium for microwave pulse compression is presented. The helically corrugated waveguide has a large variation in group-velocity with frequency in a region far from cut-off. This compressor does not suffer from reflections associated with operation near cut-off and therefore can be used at the output of a high-power microwave device.

G. Burt; S. V. Samsonov; K. Ronald; V. L. Bratman; A. R. Young; G. G. Denisov; A. D. R. Phelps; A. W. Cross; I. V. Konoplev; W. He

2004-01-01

375

Failure Limiting Pipe Expansion Joint.  

National Technical Information Service (NTIS)

The patent application describes a failure limiting pipe expansion joint for fluid conduits. It comprises a bellows, single or multi-ply, welded into each pipe section, a ribbed inner sleeve welded to the pipe at one end of the expansion joint; an outer s...

F. A. Flint

1974-01-01

376

Transient flow in pipe networks  

Microsoft Academic Search

In order to apply the fixed-grid method of characteristics to transient flow in multi-pipe systems, some pipe reaches may not satisfy the Courant condition. Various numerical techniques can be applied for these reaches. In the present study, the finite difference or interpolation techniques are coupled with the method of characteristics. The location of the disproportionate pipe, which does not satisfy

Hossein M. V. Sam Ani; Alireza Khayatzadeh

2002-01-01

377

Pump assisted heat pipe system  

Microsoft Academic Search

A laboratory model of a pump assisted heat pipe has been fabricated and tested in order to assess the potential for advanced thermal systems for future spacecraft. New arterial heat pipes with axial grooves and gear pump driven through a magnetic coupling have been developed for this purpose and two sets of heat pipe, 0.2 m and 1 m models,

Y. Miyazaki; S. Oshima; M. Furukawa; R. Imai

1988-01-01

378

Optimal disturbances in pipe flows  

Microsoft Academic Search

The growth of optimal disturbances in pipe Poiseuille flow and in a rotating pipe is investigated. In pipe Poiseuille flow the role of a pair of nearly parallel least stable modes, as a key element of the transient growth mechanism, is explored. Temporal and spatial disturbances are analyzed. The time and distance, at which the maximum energy amplification of an

Guy Ben-Dov; Jacob Cohen

2004-01-01

379

Deployable heat-pipe radiator  

NASA Technical Reports Server (NTRS)

Loop temperatures are controlled effectively under varying load conditions. Radiator has four separate pieces of hardware: heat-pipe panel, flexible heat-pipe leader, heat exchanger, fluid header. Single-fluid transport capacities of about 850 watts, corresponding to 51,000 watt-inches, have been achieved in 90 degree bend orientation of heat-pipe header.

Edelstein, F.

1978-01-01

380

Electrohydrodynamically augmented micro heat pipes  

Microsoft Academic Search

For high power density dissipation, micro heat pipes and micro grooves have demonstrated much promise. Several experimental investigations were conducted to evaluate the potential benefits of electrohydrodynamic (EHD) forces on the operation of micro heat pipes. In these experiments, electric fields were used to orient and guide the flow of the dielectric liquid within the micro heat pipes from the

Zhiquan Yu

2001-01-01

381

Reusable high-temperature heat pipes and heat pipe panels  

NASA Technical Reports Server (NTRS)

A reusable, durable heat pipe which is capable of operating at temperatures up to about 3000 F in an oxidizing environment and at temperatures above 3000 F in an inert or vacuum environment is produced by embedding a refractory metal pipe within a carbon-carbon composite structure. A reusable, durable heat pipe panel is made from an array of refractory-metal pipes spaced from each other. The reusable, durable, heat-pipe is employed to fabricate a hypersonic vehicle leading edge and nose cap.

Camarda, Charles J. (inventor); Ransone, Philip O. (inventor)

1989-01-01

382

Defect characterization in pipe-to-pipe welds in large diameter stainless steel piping  

SciTech Connect

Metallurgical evaluation of pipe-to-pipe welds in large-diameter, Type 304 stainless steel piping used to construct the moderator/coolant water systems for Savannah River Site reactors has demonstrated that small weld defects found in this 1950-vintage system do not compromise the integrity of the system. The weld defects were too small for detection by the pre-service standard radiographic inspection, but were found through systematic ultrasonic testing (UT) and penetrant testing (PT) evaluations of piping that had been removed during upgrades to the piping system. The defects include lack of weld penetration, slag inclusions, and other weld metal discontinuities. These discontinuities typically did not propagate during more than 35 years of service. The defects examined were too small and isolated to degrade the mechanical properties of the pipe-to-pipe weldments and therefore did not compromise the integrity of the piping system. 14 refs., 7 figs.

Rawl, D.E. Jr.; West, S.L.; Wheeler, D.A.; Louthan, M.R. Jr.

1990-01-01

383

Experimental investigation on the convective heat transfer enhancement for highly viscous fluids in helical coiled corrugated tubes  

NASA Astrophysics Data System (ADS)

In the present analysis, the forced convective heat transfer in smooth and corrugated helical coiled tubes was experimentally studied in the Reynolds and Dean number ranges 50÷1200 and 12÷295 respectively, by adopting Ethylene Glycol as working fluid. The primary aim of the investigation is to study the combined effect of the wall curvature and of the wall corrugation in the thermal entrance region for highly viscous fluids. Two coiled tubes with a curvature ratio of about 0.06, one with smooth wall and the other with spirally corrugated wall, were investigated under the uniform heat flux boundary condition. The main conclusion is that in the Reynolds number range analyzed, both curvature and corrugation enhance the heat transfer. For Dean number values lower than about 120 the wall curvature effect prevails, and the heat transfer enhancement reflects Nusselt numbers that are approximately 2-3 times higher than the straight smooth section. For greater Dean number values, the wall corrugation instead prevails. In fact the corrugated coiled tube reaches Nusselt number values which are up to 8 times higher than the ones expected for the smooth straight tube. The smooth coiled tube shows instead thermal performances at maximum 3.6 times over the straight section.

Rainieri, S.; Bozzoli, F.; Cattani, L.; Pagliarini, G.

2012-11-01

384

Structural testing of corrugated asbestos-cement roof panels at the Hanford Facilities, Richland, Washington  

SciTech Connect

This report describes a roof testing program that was carried out at the 105KE/KW Spent Fuel Storage Basins and their surrounding facilities at the Hanford Site in Richland, Washington. The roof panels were constructed in the mid 1950`s of corrugated asbestos-cement (A/C), which showed common signs of aging. Based on the construction specifications, the panels capacity to meet current design standards was questioned. Both laboratory and in-situ load testing of the corrugated A/C panels was conducted. The objective of the complete test program was to determine the structural integrity of the existing A/C roof panels installed in the 105KE and 105KW facilities. The data from these tests indicated that the roofs are capable of resisting the design loads and are considered safe. A second phase test to address the roof resistance to personnel and roof removal/roofing system installation equipment was recommended and is underway.

Moustafa, S.E.; Rodehaver, S.M. [Wiss, Janney, Elstner Associates, Inc., Seattle, WA (United States); Frier, W.A. [Westinghouse Hanford Co., Richland, WA (United States)

1993-10-01

385

Extrinsic Fabry-Perot pressure sensor using single deeply corrugated diaphragm technique  

NASA Astrophysics Data System (ADS)

In this study, an analytical model, taking into account the coupled photoelastic and thermal-optical effects, is established to evaluate the temperature dependence of a single-chip silicon micromachined Fabry-Perot pressure sensor. The results show that temperature variation has significant impact on the micromachined Fabry-Perot pressure sensor with conventional flat diaphragm. A new membrane-type silicon micromachined Fabry-Perot pressure sensor with a novel deeply corrugated diaphragm is then proposed. The sensor is fabricated on a single-chip using both surface- and bulk-micromachining techniques. Both analytical and experimental results show that the cross-sensitivity to temperature of Fabry-Perot pressure sensors, can be substantially alleviated by the proposed single deeply corrugated diaphragm/mirror.

Guo, D. G.; Wang, W. J.; Lin, Rongming

2004-01-01

386

Heat pipe investigations  

NASA Technical Reports Server (NTRS)

Techniques associated with thermal-vacuum and bench testing, along with flight testing of the OAO-C spacecraft heat pipes are outlined, to show that the processes used in heat transfer design and testing are adequate for good performance evaluations.

Marshburn, J. P.

1973-01-01

387

Ceramic Heat Pipe Wick.  

National Technical Information Service (NTIS)

A wick for use in a capillary loop pump heat pipe is disclosed. The wick material is an essentially uniformly porous, permeable, open-cell, silicon dioxide/aluminum oxide inorganic ceramic foam having a silica fiber ratio, by weight, of about 78 to 22, re...

B. Seidenberg T. Swanson

1989-01-01

388

Flexible pipe crawling device.  

National Technical Information Service (NTIS)

This invention is comprised of an apparatus for moving through the linear and non-linear segments of piping systems. The apparatus comprises a front leg assembly, a rear leg assembly, means for extension and retraction of said front and rear leg assembles...

W. T. Zollinger

1993-01-01

389

Flexible Heat Pipe  

NASA Technical Reports Server (NTRS)

Narrow Tube carries 10 watts or more to moving parts. Heat pipe 12 inches long and diameter of 0.312 inch (7.92mm). Bent to minimum radius of 2.5 blocks. Flexible section made of 321 stainless steel tubing (Cajon Flexible Tubing or equivalent). Evaporator and condenser made of oxygen free copper. Working fluid methanol.

Bienert, W. B.; Wolf, D. A.

1985-01-01

390

Corrugated pyramidal horn feed model for single-offset reflector analysis  

Microsoft Academic Search

A corrugated pyramidal horn (CPH) feed model which takes into account the phase error factor has been developed, using Fresnel integrals, for single-offset reflector analysis. The secondary patterns of single-offset reflectors are predicted using a physical optics method to integrate the induced currents on the reflector, based on the Bessel-Jacobi series. Good agreement is found between model data and previous

M. Calvo; D. Ferreras; E. Vega

1985-01-01

391

Highly efficient antenna system using a corrugated horn and scanning hyperbolic reflector  

NASA Technical Reports Server (NTRS)

In a horn-reflector antenna system for producing a spherical aperture phase front, a corrugated conical horn illuminates a section of a hyperbolic reflector to produce a spherical aperture phase front. This front produces a far field beam with low sidelobes and high beam efficiency. The system is insensitive to frequency and polarization changes, and is also insensitive to orientation about the axis of the conical horn for beam scanning.

Green, K. A. (inventor)

1976-01-01

392

A Ku-K Dual-Band Compact Circular Corrugated Horn for Satellite Communications  

Microsoft Academic Search

The design of a compact dual-band circular corrugated horn for satellite services in the Ku\\/K-bands is presented in this letter. The horn geometry has been obtained by a suitable design approach, which leads to the definition of a good starting point that is subsequently refined by a rapidly converging optimization technique. The tight agreement between measured and simulated data validates

Giuseppe Addamo; Oscar Antonio Peverini; Riccardo Tascone; Giuseppe Virone; Pierluigi Cecchini; Renato Orta

2009-01-01

393

Efficient analysis of arrays of rectangular corrugated horns: the synthetic aperture function approach  

Microsoft Academic Search

This paper presents a procedure to reduce the computational effort for the full-wave analysis of corrugated or stepped rectangular horns\\/cavities, open-ended on an infinite ground plane. This procedure, framed in the method of moments (MoM), is based on the construction of appropriate basis functions generated by solving the problem of one element in isolation. These functions are termed \\

Paolo Focardi; Angelo Freni; Stefano Maci; Giuseppe Vecchi

2005-01-01

394

Polarization transformation in irregular circular waveguides with helical corrugation and gyrotropic filling  

Microsoft Academic Search

Wave propagation in circular waveguides with helical corrugation of walls and longitudinal gyrotropic filling is considered. The Krylov-Bogoliubov-Mitropolsky method is applied to solution of the perturbed boundary-value problem for electric and magnetic scalar potentials. A system of coupled differential equations for complex amplitudes of propagating waves is obtained in a first approximation of the asymptotic method. A variation of the

V. F. Borulko

1998-01-01

395

Optimization of frequency-modulated pulse compression in a sectioned waveguide with a helically corrugated surface  

Microsoft Academic Search

A method of considerably elevating (by 20–30 times) the peak power of frequency-modulated microwave pulses by passive compression\\u000a in a waveguide with a helically corrugated surface used as a dispersive medium is considered. It is shown that the use of\\u000a a sectioned compression waveguide (i.e., a waveguide consisting of several sections connected to each other with slightly\\u000a differing parameters) considerably

S. V. Mishakin; S. V. Samsonov

2009-01-01

396

A W-band Gyro-BWO based on helically corrugated waveguide  

Microsoft Academic Search

A W-band gyrotron backward wave oscillator (Gyro-BWO) with a helically corrugated waveguide as the beam- wave interaction region and a cusp gun as the electron beam source is presented. The electron beam system and the beam- wave interaction were optimized for output power and frequency bandwidth by numerical simulations. A 3 dB bandwidth of -84- 104 GHz and output power

Wenlong He; A. D. R. Phelps; C. R. Donaldson; A. W. Cross; K. Ronald

2007-01-01

397

A W-band gyrotron travelling wave amplifier using a helically corrugated waveguide  

Microsoft Academic Search

A gyrotron traveling wave amplifier (gyro-TWA) with a cusp electron gun and a helically corrugated waveguide operating in the W-band is presented. The large orbit electron beam from the cusp gun interacts resonantly with an ideal eigenwave existing in the interaction region based on the cyclotron resonance maser instability. When driven by the electron beam of energy 40 keV and

W. He; A. D. R. Phelps; A. W. Cross; C. R. Donaldson; K. Ronald

2008-01-01

398

Gyro-TWTs and Gyro-BWOs with helically corrugated waveguides  

Microsoft Academic Search

Recent results on low-relativistic second-harmonic gyro-devices using a microwave system in the form of a helically corrugated waveguide are presented. New Ka-band gyro-TWT is designed to operate with peak power of 100-120 kW, average power up to 10 kW and frequency bandwidth of about 10%. In the first experimental test a peak power of 130 kW, efficiency of 22-24% and

Sergey V. Samsonov; Vladimir L. Bratman; Gregory G. Denisov; Igor G. Gachev; M. Yu. Glyavin; Vladimir N. Manuilov

2007-01-01

399

Compression of frequency-swept microwave pulses using a helically corrugated waveguide  

Microsoft Academic Search

Microwave pulse compression is an important area of research in vacuum electronics, with important applications for linear accelerators, RADAR and non-linear testing. The principles and methods of pulse compression differ greatly depending on the application. The concept of producing ultra-high-power nanosecond microwave pulses, using passive sweep-frequency compression, was studied. A novel waveguide with a helical corrugation of its inner surface

A. W. Cross; P. MacInnes; S. V. Samsonov; A. D. R. Phelps; G. Burt; K. Ronald; V. L. Bratman; G. G. Denisov; A. R. Young; C. G. Whyte; W. He; I. V. Konoplev; H. Yin

2005-01-01

400

A W-band gyro-TWA using a helically corrugated waveguide  

Microsoft Academic Search

A W-band gyrotron travelling wave amplifier (gyro-TWA) with a cusp electron gun and a helically corrugated waveguide is presented. The large orbit electron beam from the cusp gun interacts resonantly with an ideal eigenwave existing in the interaction region based on the cyclotron resonance maser instability. When driven by the 40 keV, 1.5 A electron beam the amplifier was simulated

W. He; A. D. R. Phelps; C. R. Donaldson; A. W. Cross; L. Zhang; K. Ronald

2010-01-01

401

Polarization Transformation In Irregular Circular Waveguides With Helical Corrugation And Gyrotropic Filling  

Microsoft Academic Search

Wave propagation in circular waveguides with helical corrugation of walls and longitudinally gyrotropic filling is considered. JSrylov-Bogoliubov-Mitropolsky method is applied to solution of periukd boundary-value problem for electric and magnaic scalar potentials. A system of coupled differential equations for complex amplitudes of propagating waves is obtained ir, a first approximation of the asymptotic method. A variation of polarization parameters along

V. F. Borulko

1998-01-01

402

Experimental demonstration of a W-band gyro-BWO using a helically corrugated waveguide  

Microsoft Academic Search

The experimental demonstration of a gyrotron backward wave oscillator (gyro-BWO) using a cusp electron gun and helically corrugated waveguide will be presented. Operating in the W-band frequency range the gyro-BWO is predicted to output ~10 kW with a frequency tuning range of 85-104 GHz at 18% electronic efficiency before the energy recovery. The annular axis-encircling electron beam has been experimentally

C. R. Donaldson; W. He; A. D. R. Phelps; F. Li; L. Zhang; A. W. Cross; K. Ronald; C. W. Robertson; C. G. Whyte; A. R. Young

2010-01-01

403

Thin film deposition on a corrugated surface: A molecular dynamics approach  

NASA Astrophysics Data System (ADS)

This paper presents the use of molecular dynamics (MD) simulation in the investigation of the surface topography of early-stage film growth on a GMR (giant-magnetoresistance) corrugated structure. The size of the simulated system is limited in order to reduce the computational workload. The numerical model adopts the Morse potential and the Verlet-leapfrog time evolution scheme [R.W. Hockney, 1970; D. Potter, 1972 (Chapter 5). [1

Chen, Bin-Hao; Chen, Cha'o.-Kuang; Chang, Shing Cheng

2007-07-01

404

Microstructures and dislocation configurations in nanostructured Cu processed by repetitive corrugation and straightening  

Microsoft Academic Search

The microstructures and dislocation configurations in nanostructured Cu processed by a new technique, repetitive corrugation and straightening (RCS), were studied using transmission electron microcopy (TEM) and high resolution TEM. Most dislocations belong to 60° type and tend to pile up along the {111} slip planes. Microstructural features including low-angle grain boundaries (GBs), high-angle GBs, and equilibrium and non-equilibrium GBs and

J. Y. Huang; Y. T. Zhu; H. Jiang; T. C. Lowe

2001-01-01

405

Effects of Antimicrobial Peptide Revealed by Simulations: Translocation, Pore Formation, Membrane Corrugation and Euler Buckling  

PubMed Central

We explore the effects of the peripheral and transmembrane antimicrobial peptides on the lipid bilayer membrane by using the coarse grained Dissipative Particle Dynamics simulations. We study peptide/lipid membrane complexes by considering peptides with various structure, hydrophobicity and peptide/lipid interaction strength. The role of lipid/water interaction is also discussed. We discuss a rich variety of membrane morphological changes induced by peptides, such as pore formation, membrane corrugation and Euler buckling.

Chen, Licui; Jia, Nana; Gao, Lianghui; Fang, Weihai; Golubovic, Leonardo

2013-01-01

406

Corrugation-pitch-modulated DFB semiconductor lasers realized by common holographic exposure  

NASA Astrophysics Data System (ADS)

Experimental results of corrugation-pitch-modulated (CPM) DFB lasers with distributed phase shift (DPS) based on reconstruction-equivalent-chirp (REC) technique are demonstrated. The DPS can flatten the light intensity distribution along the laser cavity and reduce the spatial hole burning (SHB). The lasers have good single longitudinal mode (SLM) property even under high injection current. Thanks to the sampling technique, the grating can be easily fabricated by holographic exposure and conventional lithograph.

Li, Simin; Li, Lianyan; Shi, Yuechun; Cao, Baoli; Guo, Renjia; Zheng, Junshou; Chen, Xiangfei

2014-07-01

407

Ohmic losses in coaxial resonators with longitudinal inner-outer corrugation  

NASA Astrophysics Data System (ADS)

In this paper, a coaxial resonator with longitudinal inner-outer corrugation is introduced. Its eigen-equation and expression of ohmic losses are derived. Ohmic losses in the cavity are investigated. Results show that ohmic losses in the outer and inner conductors share a similar variation trend, while the former is larger than the later. What's more, changes of the inner and outer slot depth and width induce different variations of ohmic losses on the surface of the inner and outer conductors.

Shenyong Hou, A.; Sheng Yu, B.; Hongfu Li, C.; Qixiang Zhao, D.; Xiang Li, E.

2013-05-01

408

Ohmic losses in coaxial resonators with longitudinal inner-outer corrugation  

SciTech Connect

In this paper, a coaxial resonator with longitudinal inner-outer corrugation is introduced. Its eigen-equation and expression of ohmic losses are derived. Ohmic losses in the cavity are investigated. Results show that ohmic losses in the outer and inner conductors share a similar variation trend, while the former is larger than the later. What's more, changes of the inner and outer slot depth and width induce different variations of ohmic losses on the surface of the inner and outer conductors.

Shenyong Hou, A. [Terahertz Science and Technology Research Center, University of Electronics Science and Technology of China, Chengdu 610054 (China) [Terahertz Science and Technology Research Center, University of Electronics Science and Technology of China, Chengdu 610054 (China); Yangtze Normal University, Chongqing 408001 (China); Sheng Yu, B.; Hongfu Li, C.; Qixiang Zhao, D. [Terahertz Science and Technology Research Center, University of Electronics Science and Technology of China, Chengdu 610054 (China)] [Terahertz Science and Technology Research Center, University of Electronics Science and Technology of China, Chengdu 610054 (China); Xiang Li, E. [Terahertz Science and Technology Research Center, University of Electronics Science and Technology of China, Chengdu 610054 (China) [Terahertz Science and Technology Research Center, University of Electronics Science and Technology of China, Chengdu 610054 (China); Queen Mary University of London, London E1 4NS (United Kingdom)

2013-05-15

409

Effects of corrugation angle on developing laminar forced convection and entropy generation in a wavy channel  

Microsoft Academic Search

This paper investigates the effects of corrugation angle (?) on the developing laminar forced convection and entropy generation in a wavy channel with numerical methods. The studied\\u000a cases cover ? = 10-, 15-, 20-, 25-, 30- and 35?, whilst Reynolds number (Re) is varied as 100, 200 and 400. The analyzed flow characteristics include recirculating flows, secondary vortices, temperature\\u000a distributions, and friction

Tzu-Hsiang Ko

2007-01-01

410

MTR BUILDING, TRA603. EAST SIDE. CAMERA FACING WEST. CORRUGATED IRON ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

MTR BUILDING, TRA-603. EAST SIDE. CAMERA FACING WEST. CORRUGATED IRON BUILDING MARKED WITH "X" IS TRA-651. TRA-626, TO ITS RIGHT, HOUSED COMPRESSOR EQUIPMENT FOR THE AIRCRAFT NUCLEAR PROPULSION PROGRAM. LATER, IT WAS USED FOR STORAGE. INL NEGATIVE NO. HD46-42-4. Mike Crane, Photographer, April 2005 - Idaho National Engineering Laboratory, Test Reactor Area, Materials & Engineering Test Reactors, Scoville, Butte County, ID

411

Interaction of Helium with a Metal Surface: Determination of Corrugation Profile of Cu(110)  

NASA Astrophysics Data System (ADS)

Starting from a microscopic description of the interaction of a helium atom with a metal surface, a simple approximate result is derived which shows that the lateral corrugation of the repulsive potential decreases exponentially with distance z from the surface. For Cu(110) this theory leads to an interaction potential that reproduces all the observed bound states and gives a quantitative fit of recent helium diffraction data taken at various incident energies and angles.

Harris, J.; Liebsch, A.

1982-08-01

412

Fast diffusion along defects and corrugations in phospholipid P beta, liquid crystals.  

PubMed Central

The diffusion of a fluorescent lipid analogue in liquid crystals of the anisotropic P beta, phase of dimyristoylphosphatidylcholine (DMPC) had been found to be highly variable, suggesting structural defect pathways. Fluorescence photobleaching recovery (FPR) experiments imply two effective diffusion pathways with coefficients differing by at least 100. This is consistent with fast diffusion along submicroscopic bands of disordered material ("defects") in the bilayer corrugations characteristic of this phase. Due to strains during transformation from the L alpha phase, the axis of the corrugations is ordinarily disrupted by mosaic patches rotationally disoriented within the mean plane of the molecular bilayers, although larger oriented domains are sometimes adventitiously aligned into microscopically visible striped textures. The corrugations are also systematically aligned along positive disclinations pairs or "oily streaks." Thus, fast diffusion occurs parallel to the disclination lines and along the textured stripes. FPR results yield an upper limit on the effective diffusion in the ordered material of D less than or equal to 2 X 10(-16) cm2/s at 22 degrees C, D less than or equal to 3 X 10(-17) cm2/s at 13 degrees C. In contrast the diffusion coefficient along defect pathways where disordered ribbons are aligned is D approximately 4 X 10(-11) cm2/s at 16 degrees C. Images FIGURE 4 FIGURE 6 FIGURE 7

Schneider, M B; Chan, W K; Webb, W W

1983-01-01

413

Pressure Distribution and Velocity Profiles Around Smooth and Corrugated Cylinders of Finite Span  

NASA Astrophysics Data System (ADS)

In this work the pressure distribution and velocity profiles around two finite aspect ratio (AR˜1) cylinders is investigated for Reynolds numbers ranging from 1x10^5 to 9x10^5. The first cylinder is smooth, while the second cylinder has a corrugated surface with channels cut in the r-? plane. The channels are approximately half the diameter in depth and twenty percent of the diameter in width. The apparent aspect ratio was increased by the addition of endplates and the resulting pressure and velocity distributions were compared. The results show that the cylinder with corrugations has a significantly higher minimum pressure coefficient compared to the smooth cylinder at all Reynolds numbers tested. Adding end plates to the cylinders caused the minimum pressure coefficients to decrease and approach that of an infinitely long smooth circular cylinder. Velocity profiles indicate that the corrugated cylinder has a significantly thicker viscous/separated region compared to the smooth cylinder. A strong dependence on Reynolds number was shown for both pressure and velocity in the range investigated.

Parker, Mike; Bohl, Doug

2008-11-01

414

Fabrication and evaluation of superplastically formed/weld-brazed corrugated compression panels with beaded webs  

NASA Technical Reports Server (NTRS)

A study was made to investigate the feasibility of superplastically forming corrugated panels with beaded webs and to demonstrate the structural integrity of these panels by testing. The test panels in the study consist of superplastically formed titanium alloy Ti-6Al-4V half-hat elements that are joined by weld-brazing to titanium alloy Ti-6Al-4V caps to form either single-corrugation compression panels or multiple-corrugation compression panels. Stretching and subsequent thinning of the titanium sheet during superplastic forming is reduced by approximately 35 percent with a shallow half-hat die concept instead of a deep die concept and results in a more uniform thickness across the beaded webs. The complete panels are tested in end compression at room temperature and the results compared with analysis. The heavily loaded panels failed at loads approaching the yield strength of the titanium material. At maximum load, the caps wrinkled locally accompanied with separation of the weld-braze joint in the wrinkle. None of the panels tested, however, failed catastrophically in the weld-braze joint. Experimental test results are in good agreement with structural analysis of the panels.

Royster, D. M.; Davis, R. C.; Shinn, J. M., Jr.; Bales, T. T.; Wiant, H. R.

1985-01-01

415

Corrugated Waveguide and Directional Coupler for CW 250-GHz Gyrotron DNP Experiments  

PubMed Central

A 250-GHz corrugated transmission line with a directional coupler for forward and backward power monitoring has been constructed and tested for use with a 25-W continuous-wave gyrotron for dynamic nuclear polarization (DNP) experiments. The main corrugated line (22-mm internal diameter, 2.4-m long) connects the gyrotron output to the DNP probe input. The directional coupler, inserted approximately midway, is a four-port crossed waveguide beamsplitter design. Two beamsplitters, a quartz plate and ten-wire array, were tested with output coupling of 2.5% (?16 dB) at 250.6 GHz and 1.6% (?18 dB), respectively. A pair of mirrors in the DNP probe transferred the gyrotron beam from the 22-mm waveguide to an 8-mm helically corrugated waveguide for transmission through the final 0.58-m distance inside the NMR magnet to the sample. The transmission-line components were all cold tested with a 248 ± 4-GHz radiometer. A total insertion loss of 0.8 dB was achieved for HE11 -mode propagation from the gyrotron to the sample with only 1% insertion loss for the 22-mm-diameter waveguide. A clean Gaussian gyrotron beam at the waveguide output and reliable forward power monitoring were achieved for many hours of continuous operation.

Woskov, Paul P.; Bajaj, Vikram S.; Hornstein, Melissa K.; Temkin, Richard J.; Griffin, Robert G.

2007-01-01

416

Corrugated Waveguide and Directional Coupler for CW 250-GHz Gyrotron DNP Experiments.  

PubMed

A 250-GHz corrugated transmission line with a directional coupler for forward and backward power monitoring has been constructed and tested for use with a 25-W continuous-wave gyrotron for dynamic nuclear polarization (DNP) experiments. The main corrugated line (22-mm internal diameter, 2.4-m long) connects the gyrotron output to the DNP probe input. The directional coupler, inserted approximately midway, is a four-port crossed waveguide beamsplitter design. Two beamsplitters, a quartz plate and ten-wire array, were tested with output coupling of 2.5% (-16 dB) at 250.6 GHz and 1.6% (-18 dB), respectively. A pair of mirrors in the DNP probe transferred the gyrotron beam from the 22-mm waveguide to an 8-mm helically corrugated waveguide for transmission through the final 0.58-m distance inside the NMR magnet to the sample. The transmission-line components were all cold tested with a 248 ± 4-GHz radiometer. A total insertion loss of 0.8 dB was achieved for HE(11) -mode propagation from the gyrotron to the sample with only 1% insertion loss for the 22-mm-diameter waveguide. A clean Gaussian gyrotron beam at the waveguide output and reliable forward power monitoring were achieved for many hours of continuous operation. PMID:17901907

Woskov, Paul P; Bajaj, Vikram S; Hornstein, Melissa K; Temkin, Richard J; Griffin, Robert G

2005-06-01

417

Determination of corrugation and friction of Cu(111) toward adsorption and motion of Ne and Xe  

NASA Astrophysics Data System (ADS)

The corrugation feature of potential energy surfaces (PESs) for rare-gas (RG) adlayers on metal surfaces has been extensively explored in the positive adsorption energy part. Here, we show that opposite corrugation features may also happen in the negative adsorption energy side for Ne and Xe on Cu(111). While the PES of Ne/Cu(111) is corrugated near the equilibrium adsorption geometry, i.e., Ne prefers the hollow site, the PES of Xe/Cu(111) is anticorrugated, i.e., Xe prefers the atop site. The weak hybridization of RG p and Cu d states is critical for this qualitative difference. Furthermore, the calculated activation energies indicate that Ne may move on Cu(111) at a very low temperature, whereas Xe motion can be activated only above 35 K. We found that the inclusion of the nonlocal van der Waals correction is essential for the correct determination of adsorption and motion energetics for RG adatoms on metals through density functional calculations.

Zhang, Y. N.; Bortolani, V.; Mistura, G.

2014-04-01

418

The contact mechanical nonlinearities of a mathematical model of a railway wheel rolling over corrugated rail  

NASA Astrophysics Data System (ADS)

The results of the investigations carried out on possible nonlinear contact mechanical effects of a wheel rolling over corrugated rail are discussed. The applied method of investigation takes as a starting point normal force and creep variations calculated by using a linear model of corrugations. Predicted normal loads between wheel and rail were taken as an input for the solution of the normal contact problem using an approximate, numerical method for non-Hertzian contact. The results of normal contact calculations were analyzed from the point of view of the geometry of contact and basic contact mechanical quantities which influence vertical dynamics of the system, generating the creep forces and wear. Similar analysis was carried out for Hertzian assumptions with the use of the same method for non-Hertzian normal contact problem. The main conclusion arrived at is that the discrepancies due to Hertzian description of the contact mechanical part of the linear model against the non-Hertzian description are most strongly pronounced when the wheel traverses the trough of the corrugation and, that might lead to the significant overall discrepancies in predictions obtained with the two different contact mechanical parts of the model.

Piotrowski, Jerzy

1991-09-01

419

Optimization of corrugated-QWIPs for large format, high quantum efficiency, and multi-color FPAs  

NASA Astrophysics Data System (ADS)

Previously, we demonstrated a large format 1024 × 1024 corrugated quantum well infrared photodetector focal plane array (C-QWIP FPA). The FPA has a cutoff at 8.6 ?m and is BLIP at 76 K with f/1.8 optics. The pixel had a shallow trapezoidal geometry that simplified processing but limited the quantum efficiency QE. In this paper, we will present two approaches to achieve a larger QE for the C-QWIPs. The first approach increases the size of the corrugations for more active volume and adopts a nearly triangular pixel geometry for larger light reflecting surfaces. With these improvements, QE is predicted to be about 35% for a pair of inclined sidewalls, which is more than twice the previous value. The second approach is to use Fabry-Perot resonant oscillations inside the corrugated cavities to enhance the vertical electric field strength. With this approach, a larger QE of 50% can be achieved within certain spectral regions without using either very thick active layers or anti-reflection coatings. The former approach has been adopted to produce two FPAs, and the preliminary experimental results will be discussed. In this paper, we also describe using voltage tunable detector materials to achieve multi-color capability for these FPAs.

Choi, Kwong-Kit; Monroy, Carlos; Swaminathan, Venkataraman; Tamir, Theodor; Leung, Ming; Devitt, John; Forrai, David; Endres, Darrel

2007-04-01

420

Optimization of corrugated-QWIPs for large format, high-quantum-efficiency, and multicolor FPAs  

NASA Astrophysics Data System (ADS)

Previously, we demonstrated a large format 1024 x 1024 corrugated quantum well infrared photodetector focal plane array (C-QWIP FPA). The FPA has a cutoff at 8.6 ?m and is BLIP at 76 K with f/1.8 optics. The pixel had a shallow trapezoidal geometry that simplified processing but limited the quantum efficiency QE. In this paper, we will present two approaches to achieve a larger QE for the C-QWIPs. The first approach increases the size of the corrugations for more active volume and adopts a nearly triangular pixel geometry for larger light reflecting surfaces. With these improvements, QE is predicted to be about 35% for a pair of inclined sidewalls, which is more than twice the previous value. The second approach is to use Fabry-Perot resonant oscillations inside the corrugated cavities to enhance the vertical electric field strength. With this approach, a larger QE of 50% can be achieved within certain spectral regions without using either very thick active layers or anti-reflection coatings. The former approach has been adopted to produce a series single color FPAs, and the experimental results will be discussed in a companion paper. In this paper, we also describe using voltage tunable detector materials to achieve multi-color capability for these FPAs.

Choi, Kwong-Kit; Monroy, Carlos; Swaminathan, Venkataraman; Tamir, Theodor; Leung, Ming; Devitt, John; Forrai, David; Endres, Darrel

2006-06-01

421

Investigations of heat transfer and friction characteristics of compact cross-corrugated recuperators  

NASA Astrophysics Data System (ADS)

As one of the key devices in the high temperature gas turbine system, cross-corrugated recuperators provide high heat transfer capabilities with compact size, light weight, strong mechanical strength and are mandatory to achieve 30 % electrical efficiency or higher for micro turbine engines. Flow in such geometries is usually laminar with lower Reynolds numbers. In order to understand mechanisms of flowing and heat transfer, periodic fully developed fluid flow and heat transfer in two types of cross-corrugated structures with inclination angle at 90° are investigated numerically and experimentally. Periodicity was used to reduce the complexity of the channel geometry and enables the smallest possible segment of the flow channel to be modeled. The velocity and temperature distributions were obtained in the three-dimensional complex domain. Besides a detailed flow analysis, comparison of the local heat and mass transfer and the pressure losses for these geometries are presented. It is shown that the flow phenomena caused by the different geometries were of significant influence on the homogeneity and on the quantity of the local heat and mass transfer as well as on the pressure drop. As a recuperator for micro turbine engines, cross-corrugated sinusoidal channels are more preferable to triangular channels.

Zhou, Guo-Yan; Tu, Shan-Tung; Ma, Hu-gen

2014-04-01

422

Pipe handling apparatus for reel pipe laying system  

SciTech Connect

An offshore system for laying a continuous length of pipe on the sea bottom from a pipe-carrying reel adapted to be mounted on a carrier vessel having an improved pipe handling and conditioning apparatus for working on the unspooled pipe. The improved apparatus includes a pipe straightener for imparting a reverse plastic bending moment to the unspooled pipe passing therethrough , and which comprises at least two pairs of pipe support rollers, each pair being aligned along the pipe path and mounted for rotational movement about respective rotational axes normal to the pipe path and parallel to the plane of the deck of the carrier vessel, and for pivoting movement about a pivot axis located between and substantially parallel to the respective rotational axes. A straightener carriage mounts the pipe straightening means for movement (1) about a pivot axis substantially parallel to the rotational axis of the reel, (2) in a substantially vertical direction relative to the deck of the carrier vessel, and (3) in a direction substantially parallel to the rotational axis of the reel.

Brown, W.A.; Cha, J.H.; Weldon, H.P.; Whyte, D.G.

1981-01-06

423

Six Centuries Old Spiral of Vertical Corrugations in Saturn's C-Ring  

NASA Astrophysics Data System (ADS)

Likely evidence of nearly six centuries old collision of captured cometary material with Saturn's Ring C is uncovered in recent Cassini Radio Science ring observations. Three Cassini ring occultation experiments were especially designed so that radio signals transmitted by Cassini to the Earth pass through the rings when the rings are nearly closed as viewed by the ground receiving stations of the NASA Deep Space Network (DSN). In this special geometry, the long path of the radio signals through the rings enhances sensitivity to detection of very tenuous ring material and allows ~400 meters resolution profiling of its radial structure. The observations uncover previously undetectable quasi-periodic optical depth undulations in 4 sub-regions of the innermost ~4000 km of Ring C (~74,480-77,740 km). The structure modulates a tenuous background optical depth of ~0.05 and has peak-to-peak fluctuations < ~0.01, making detection possible only in the case of these 3 special occultations (ring opening angle of 4.8, 4.8, and 1.9 degrees; Cassini Revs 123, 125, and 133, respectively). The structure is detectable at two observation wavelengths (0.94 and 3.6 cm), at multiple observing DSN ground stations, and in data from all 3 occultations. It's characterized by two interfering "tones" of spatial wavelength ~1.3 and ~1.2 km. The wavelength increases slowly with ring radius. The behavior appears consistent with presence of vertical corrugations 4-10 meters in height likely caused by a past ring tilting event (collision with cometary debris) and subsequent differential nodal regression of particle orbits. Time evolution of the perturbations creates a tightly wound spiral pattern of ring height variations which when probed by the radio signals yield the observed tenuous quasi-periodic optical depth fluctuations. The corrugations model was proposed by Hedman et al. [Science 332, 2011] to explain intriguing 30-50 km wavelength structure observed in Cassini images (ISS) across Ring C. The RSS wavelength-radius behavior is in general agreement with the corrugation model prediction; however, important differences persist (ring mass effect?). The much shorter RSS corrugation wavelength compared with ISS implies a separate ring tilting event that is older by ~600 years (late 1300's), and the two tones separation suggests two sub-events ~50 years apart. Together with reported detection of similar corrugations within the tenuous Jovian rings [Showalter et al., Science 332, 2011], the collective observations suggest that these ring-plane-tilting events may not be rare.

Marouf, E. A.; French, R. G.; Rappaport, N. J.; Wong, K.; McGhee, C.; Anabtawi, A.

2011-12-01

424

Effect of discrete track support by sleepers on rail corrugation at a curved track  

NASA Astrophysics Data System (ADS)

The paper investigates into the effect of discrete track support by sleepers on the initiation and development of rail corrugation at a curved track when a railway vehicle passes through using a numerical method. The numerical method considers a combination of Kalker's rolling contact theory with non-Hertzian form, a linear frictional work model and a dynamics model of a half railway vehicle coupled with the curved track. The half-vehicle has a two-axle bogie and doubled suspension systems. It is treated as a full dynamic rigid multi-body model. In the track model, an Euler beam is used to model the rail, and the discrete track support by sleepers moving backward with respect to the vehicle running direction is considered to simulate the effect of the discrete sleeper support on the wheels/rails in rolling contact when the vehicle moves on the track. The sleeper is treated as a rigid body and the ballast bed is replaced with equivalent mass bodies. The numerical analysis exams in detail the variations of wheel/rail normal loads, the creepages, and the rail wear volume along the curved track. Their variations are much concerned with the discrete track support. The numerical results show that the discrete track support causes the fluctuating of the normal loads and creepages at a few frequencies. These frequencies comprise the passing frequency of the sleepers and the excited track resonant frequencies, which are higher than the sleeper passing frequency. Consequently, rail corrugation with several wavelengths initiates and develops. Also the results show that the contact vibrating between the curved rails and the four wheels of the same bogie has different frequencies. In this way, the different key frequencies to be excited play an important role in the initiation and development of curved rail corrugation. Therefore, the corrugations caused by the four wheels of the same bogie present different wavelengths. The paper shows and discusses the depths of the initial corrugations caused by the four wheels of the same bogie, at the entering transition curve, the circle curve and the exit transition curve of the curved track, respectively.

Jin, X. S.; Wen, Z. F.

2008-08-01

425

Explosive welding of pipes  

NASA Astrophysics Data System (ADS)

For connection by welding it is suggested to use the explosive welding method. This method is rather new. Nevertheless, it has become commonly used among the technological developments. This method can be advantageous (saving material and physical resources) comparing to its statical analogs (electron-beam welding, argon-arc welding, plasma welding, gas welding, etc.), in particular, in hard-to-reach areas due to their geographic and climatic conditions. The suggestion is to use water as filler. The principle of non-compressibility of liquid under quasi-dynamic loading is used. In one-dimensional gasdynamic and elastic-plastic calculations we determined non-deformed mass of water. Model experiments with pipes having radii R = 57 mm confirmed results of the calculations and the possibility in principle to weld pipes by explosion with use of water as filler.

Drennov, O.; Burtseva, O.; Kitin, A.

2006-08-01

426

Drill pipe protector development  

SciTech Connect

The Geothermal Drilling Organization (GDO), formed in the early 1980s by the geothermal industry and the U.S. Department of Energy (DOE) Geothermal Division, sponsors specific development projects to advance the technologies used in geothermal exploration, drilling, and production phases. Individual GDO member companies can choose to participate in specific projects that are most beneficial to their industry segment. Sandia National Laboratories is the technical interface and contracting office for the DOE in these projects. Typical projects sponsored in the past have included a high temperature borehole televiewer, drill bits, muds/polymers, rotary head seals, and this project for drill pipe protectors. This report documents the development work of Regal International for high temperature geothermal pipe protectors.

Thomerson, C.; Kenne, R. [Regal International Corp., Corsicanna, TX (United States); Wemple, R.P. [Sandia National Lab., Albuquerque, NM (United States)] [ed.] [and others

1996-03-01

427

Flow and heat/mass transfer in a wavy duct with various corrugation angles in two dimensional flow regimes  

NASA Astrophysics Data System (ADS)

In this study, two dimensional heat/mass transfer characteristics and flow features were investigated in a rectangular wavy duct with various corrugation angles. The test duct had a width of 7.3 mm and a large aspect ratio of 7.3 to simulate two dimensional characteristics. The corrugation angles used were 100°, 115°, 130°, and 145°. Numerical analysis using the commercial code FLUENT, was used to analyze the flow features. In addition, the oil-lamp black method was used for flow visualization. Local heat/mass transfer coefficients on the corrugated walls were measured using a naphthalene sublimation technique. The Reynolds number, based on the duct hydraulic diameter, was varied from 700 to 5,000. The experimental results and numerical analysis showed interesting and detailed features in the wavy duct. Main flow impinged on upstream of a pressure wall, and the flow greatly enhanced heat/mass transfer. On a suction wall, however, flow separation and reattachment dominantly affected the heat/mass transfer characteristics on the wall. As the corrugation angle decreased (it means the duct has more sharp turn), the region of flow stagnation at the front part of the pressure wall became wider. Also, the position of flow reattachment on the suction wall moved upstream as the corrugation angle decreased. A high heat transfer rate appeared at the front part of the pressure wall due to main-flow impingement, and at the front part of the suction wall due to flow reattachment. The high heat/mass transfer region by the main-flow impingement and the circulation flow induced at a valley between the pressure and suction walls changed with the corrugation angle and the Reynolds number. As the corrugation angle decreased, the flow in the wavy duct changed to transition to turbulent flow earlier.

Kwon, Hyun Goo; Hwang, Sang Dong; Cho, Hyung Hee

2008-12-01

428

Electrohydrodynamic heat pipe research  

NASA Technical Reports Server (NTRS)

Experimental and theoretical applications to electrohydrodynamic heat pipe (EHDHP) research are presented. Two problems in the research which are discussed are the prediction of the effective thermal conductance of an EHDHP with threaded grooves for fluid distribution to the evaporator of an EHDHP. Hydrodynamic equations are included along with a discussion of boundary conditions and burn-out conditions. A discussion of the theoretical and experimental results is presented.

Jones, T. B.; Perry, M. P.

1973-01-01

429

Heat Pipe Systems  

NASA Astrophysics Data System (ADS)

Solar Fundamentals, Inc.'s hot water system employs space-derived heat pipe technology. It is used by a meat packing plant to heat water for cleaning processing machinery. Unit is complete system with water heater, hot water storage, electrical controls and auxiliary components. Other than fans and a circulating pump, there are no moving parts. System's unique design eliminates problems of balancing, leaking, corroding, and freezing.

1988-01-01

430

Guidable pipe plug  

DOEpatents

A plugging device for closing an opening defined by an end of a pipe with sealant comprises a cap, an extension, an inner seal, a guide, and at least one stop. The cap has an inner surface which defines a chamber adapted for retaining the sealant. The chamber is dimensioned slightly larger than the end so as to receive the end. The chamber and end define a gap therebetween. The extension has a distal end and is attached to the inner surface opposite the distal end. The inner seal is attached to the extension and sized larger than the opening. The guide is positioned forward of the inner seal and attached to the distal end. The guide is also dimensioned to be inserted into the opening. The stop is attached to the extender, and when the stop is disposed in the pipe, the stop is movable with respect to the conduit in one direction and also prevents misalignment of the cap with the pipe. A handle can also be included to allow the cap to be positioned robotically.

Glassell, Richard L. (Knoxville, TN); Babcock, Scott M. (Farragut, TN); Lewis, Benjamin E. (Farragut, TN)

2001-01-01

431

Pipe inspection using the pipe crawler. Innovative technology summary report  

SciTech Connect

The US Department of Energy (DOE) continually seeks safer and more cost-effective remediation technologies for use in the decontamination and decommissioning (D and D) of nuclear facilities. In several of the buildings at the Fernald Site, there is piping that was used to transport process materials. As the demolition of these buildings occur, disposal of this piping has become a costly issue. Currently, all process piping is cut into ten-foot or less sections, the ends of the piping are wrapped and taped to prevent the release of any potential contaminants into the air, and the piping is placed in roll off boxes for eventual repackaging and shipment to the Nevada Test Site (NTS) for disposal. Alternatives that allow for the onsite disposal of process piping are greatly desired due to the potential for dramatic savings in current offsite disposal costs. No means is currently employed to allow for the adequate inspection of the interior of piping, and consequently, process piping has been assumed to be internally contaminated and thus routinely disposed of at NTS. The BTX-II system incorporates a high-resolution micro color camera with lightheads, cabling, a monitor, and a video recorder. The complete probe is capable of inspecting pipes with an internal diameter (ID) as small as 1.4 inches. By using readily interchangeable lightheads, the same system is capable of inspecting piping up to 24 inches in ID. The original development of the BTX system was for inspection of boiler tubes and small diameter pipes for build-up, pitting, and corrosion. However, the system is well suited for inspecting the interior of most types of piping and other small, confined areas. The report describes the technology, its performance, uses, cost, regulatory and policy issues, and lessons learned.

NONE

1999-05-01

432

High Toughness ERW Pipes for Arctic Use.  

National Technical Information Service (NTIS)

Recent progress of ERW pipe manufacturing technology has made it possible for ERW pipes to substitute UOE and stainless pipes in several fields. In order to develop ERW pipe available for line pipe with high toughness at low temperature, the fundamental s...

T. Shimomura T. Takamura S. Ishiro T. Sugayoshi Y. Nagahama

1987-01-01

433

Request for Proposal 77. Horizontal Pipe Racker.  

National Technical Information Service (NTIS)

A pipe handling system will be required on the Mohole drilling platform for storing and handling a maximum quantity of 39,000 feet of drill pipe and 19,000 feet of riser pipe. An automated pipe racking system was required as an integral part of the pipe h...

1965-01-01

434

Study of near-source earthquake effects on flexible buried pipes  

NASA Astrophysics Data System (ADS)

An investigation is carried out, using strong ground motion recordings, field measurements, and new analytical models, on large diameter flexible buried pipes shaken in the 1994 Northridge earthquake near field. Case studies are presented for corrugated metal pipes (CMP) in the Van Norman Complex (VNC) vicinity in Los Angeles, California. In 1994 the VNC yielded an unprecedented number of strong motion recordings with high acceleration and velocity. These recordings contain forward directivity pulses and provided the largest velocity ever instrumentally recorded (180 cm/s). The recorded motions were significantly different in the longitudinal and transverse directions and had approximately half the amplitude at the VNC center than on the north and south ends. The seismic performances of 61 underground CMPs are presented, beginning with detailed studies of a 2.4 m diameter pipe that suffered complete lateral buckling collapse at the Lower San Fernando Dam (LSFD). The case histories identify factors controlling large diameter CMP seismic performances that are incorporated into several newly developed models for the analysis and design of buried structures. Each model progressively improves the understanding of buried pipe behavior. Simple acceleration- and strain-based pseudo-static models are initially developed to identify main causes for CMP damage. Elasto-dynamic models for transverse SV waves are later used to understand flexible pipe response in the frequency and time domains and are compared with existing solutions. Finally, pseudo-static models, which analyze pipe responses in terms of free-field strains, are formulated to account for dynamic amplification, non-vertical wave incidence, soil layering, and trench backfill soil stiffness. The elastic models are used to investigate soil-pipe interface shear stress and non-linear soil behavior and show that the maximum pipe hoop force is best characterized by assuming no interface slippage. The models explain the observed CMP performance during the 1994 earthquake and show that peak velocity is a more reliable index of flexible pipe damage than acceleration and that large seismic stresses, modulus reduction, and pore pressure increases in the embedding soils damaged the LSFD and other CMPs. Results of the field investigations and companion analyses are useful for the seismic design and strengthening of underground structures.

Davis, Craig Alan

2000-10-01

435

Radiation crosslinked plasticized PVC - pipes  

NASA Astrophysics Data System (ADS)

The efficiency of polyfunctional monomers triallyl cyanurate, allyl methacrylate, diallyl phtalate, 2-ethyl-2(hydroxy-methyl)-propanediol-(1,3) trimethacrylate, divinyl benzene and ethylene glycol dimethacrylate in radiation crosslinking of PVC was investigated. Patterns of pipes were produced and irradiated with gamma rays. The resistance to internal pressure of crosslinked PVC pipes was measured at 80°C and compared with resistance of unirradiated PVC pipes.

Hell, Z.; Ravli?, M.; Bogdanovi?, Lj.; Maleš, J.; Dvornik, I.; Ranogajec, F.; Ranogajec, M.; Tudori?-Ghemo, J.

436

Noncontact gears. I. Next-to-leading order contribution to the lateral Casimir force between corrugated parallel plates  

SciTech Connect

We calculate the lateral Casimir force between corrugated parallel plates, described by {delta}-function potentials, interacting through a scalar field, using the multiple scattering formalism. The contributions to the Casimir energy due to uncorrugated parallel plates is treated as a background from the outset. We derive the leading- and next-to-leading-order contribution to the lateral Casimir force for the case when the corrugation amplitudes are small in comparison to corrugation wavelengths. We present explicit results in terms of finite integrals for the case of the Dirichlet limit, and exact results for the weak-coupling limit, for the leading- and next-to-leading-orders. The correction due to the next-to-leading contribution is significant. In the weak coupling limit we calculate the lateral Casimir force exactly in terms of a single integral which we evaluate numerically. Exact results for the case of the weak limit allows us to estimate the error in the perturbative results. We show that the error in the lateral Casimir force, in the weak coupling limit, when the next-to-leading order contribution is included is remarkably low when the corrugation amplitudes are small in comparison to corrugation wavelengths. We expect similar conclusions to hold for the Dirichlet case. The analogous calculation for the electromagnetic case should reduce the theoretical error sufficiently for comparison with the experiments.

Cavero-Pelaez, Ines; Milton, Kimball A.; Parashar, Prachi; Shajesh, K. V. [Laboratoire Kastler Brossel, Universite Pierre et Marie Curie, ENS, CNRS, Campus Jussieu, University Paris 6, Case 74, F-75252 Paris, cedex 05 (France); Oklahoma Center for High Energy Physics and Homer L. Dodge Department of Physics and Astronomy, University of Oklahoma, Norman, Oklahoma 73019 (United States)

2008-09-15

437

Non-binding conductor load bearing roller for a gas-insulated transmission line having a corrugated outer conductor  

DOEpatents

A gas-insulated transmission line includes a corrugated outer conductor, an inner conductor disposed within and insulated from the outer conductor by means of support insulators and an insulating gas, and a non-binding transport device for supporting and permitting movement of the inner conductor/insulating support assembly axially along the corrugated outer conductor without radial displacement and for moving without binding along corrugations of any slope less than vertical. The transport device includes two movable contacts, such as skids or rollers, supported on a common pivot lever, the pivot lever being rotatably disposed about a pivot lever axis, which pivot lever axis is in turn disposed on the periphery of a support insulator or particle trap if one is used. The movable contacts are separated axially a distance equal to the axial distance between the peaks and valleys of the corrugations of the outer conductor and separated radially a distance equal to the radial distance between the peaks and valleys of the corrugations of the outer conductor. The transport device has the pivot lever axis disposed parallel to the motion of travel of the inner conductor/insulating support assembly.

Fischer, William H. (Pittsburgh, PA)

1984-01-01

438

Prediction of heat transfer coefficients and friction factors for evaporation of R-134a flowing inside corrugated tubes  

NASA Astrophysics Data System (ADS)

In this study, experimental and simulation studies of the evaporation heat transfer coefficient and pressure drop of R-134a flowing through corrugated tubes are conducted. The test section is a horizontal counter-flow concentric tube-in-tube heat exchanger 2.0 m in length. A smooth tube and corrugated tubes with inner diameters of 8.7 mm are used as the inner tube. The outer tube is made from a smooth copper tube with an inner diameter of 21.2 mm. The corrugation pitches used in this study are 5.08, 6.35, and 8.46 mm. Similarly, the corrugation depths are 1, 1.25, and 1.5 mm, respectively. The results show that the maximum heat transfer coefficient and pressure drop obtained from the corrugated tube are up to 22 and 19 % higher than those obtained from the smooth tube, respectively. In addition, the average difference of the heat transfer coefficient and pressure drop between the simulation model and experimental data are about 10 and 15 %, respectively.

Laohalertdecha, S.; Aroonrat, K.; Dalkilic, A. S.; Mahian, O.; Kaewnai, S.; Wongwises, S.

2014-04-01

439

Thermostructural applications of heat pipes  

NASA Technical Reports Server (NTRS)

The feasibility of integrating heat pipes in high temperature structure to reduce local hot spot temperature was evaluated for a variety of hypersonic aerospace vehicles. From an initial list of twenty-two potential applications, the single stage to orbit wing leading edge showed the greatest promise and was selected for preliminary design of an integrated heat pipe thermostructural system. The design consisted of a Hastelloy X assembly with sodium heat pipe passages aligned normal to the wing leading edge. A d-shaped heat pipe cross section was determined to be optimum from the standpoint of structural weight.

Peeples, M. E.; Reeder, J. C.; Sontag, K. E.

1979-01-01

440

Durability of Drainage Structures.  

National Technical Information Service (NTIS)

The study evaluated various culvert materials and/or coatings for durability. The emphasis of the evaluation was directed primarily toward corrosion for the metal pipes and loss of aggregates in reinforced concrete pipes. Culverts installed by Constructio...

K. M. Jacobs

1982-01-01

441

Longitudinal welded pipes with enhanced fatigue strength (Hifa ® pipe)  

Microsoft Academic Search

The transportation and storage of fluids in pipes can lead to cyclic loading due to fluctuating internal pressure which exceeds the normal pipeline operation range. In this special case, the design of the pipe is based on the fatigue strength rather than on the static strength. Normally a welded structure has a reduced fatigue resistance compared to a none- welded

M. Erdelen-Peppler; G. Knauf; Marewski Salzgitter; Mannesmann Forschung; O. Reepmeyer

442

Distributed-feedback Terahertz Quantum-cascade Lasers with Laterally Corrugated Metal Waveguides  

NASA Technical Reports Server (NTRS)

We report the demonstration of distributed-feedback terahertz quantum-cascade lasers based on a first-order grating fabricated via a lateral corrugation in a double-sided metal ridge waveguide. The phase of the facet reflection was precisely set by lithographically defined facets by dry etching. Single-mode emission was observed at low to moderate injection currents, although multimode emission was observed far beyond threshold owing to spatial hole burning. Finite-element simulations were used to calculate the modal and threshold characteristics for these devices, with results in good agreement with experiments.

Williams, Benjamin S.; Kumar, Sushil; Hu, Qing; Reno, John L.

2005-01-01

443

High-Gain Wide-Band Gyrotron Traveling Wave Amplifier with a Helically Corrugated Waveguide  

NASA Astrophysics Data System (ADS)

First bandwidth measurements of a novel gyrotron amplifier are presented. The coupling between the second harmonic cyclotron mode of a gyrating electron beam and the radiation field occurred in the region of near infinite phase velocity over a broad bandwidth by using a cylindrical waveguide with a helical corrugation on its internal surface. With a beam energy of 185 keV, the amplifier achieved a maximum output power of 1.1 MW, saturated gain of 37 dB, linear gain of 47 dB, saturated bandwidth of 8.4 to 10.4 GHz ( 21% relative bandwidth), and an efficiency of 29%, in good agreement with theory.

Bratman, V. L.; Cross, A. W.; Denisov, G. G.; He, W.; Phelps, A. D. R.; Ronald, K.; Samsonov, S. V.; Whyte, C. G.; Young, A. R.

2000-03-01

444

Analytical estimates of free Brownian diffusion times in corrugated narrow channels  

NASA Astrophysics Data System (ADS)

The diffusion of a suspended Brownian particle along a sinusoidally corrugated narrow channel is investigated to assess the validity of two competing analytical schemes, both based on effective one-dimensional kinetic equations, one continuous (entropic channel scheme) and the other discrete (random walker scheme). For narrow pores, the characteristic diffusion time scale is represented by the mean first exit time out of a channel compartment. Such a diffusion time has been analytically calculated in both approximate schemes; the two analytical results coincide in leading order and are in excellent agreement with the simulation data.

Bosi, Leone; Ghosh, Pulak K.; Marchesoni, Fabio

2012-11-01

445

Heat-transfer performance of a corrugated-tube thermosiphon. Part 1; Evaporator performance  

SciTech Connect

Two-phase closed thermosiphons are highly efficient heat-transfer elements with applications in terrestrial heat-transport and heat-recovery systems. In this paper, a corrugated copper tube was used as the container of the thermosiphons and distilled water was used as the working fluid. The influences of the liquid charge ratio and inclination angle on the heat-transfer performance were studied. It was found that the optimum liquid charge ratio to evaporator volume is 40 percent and the maximum performance is obtained at an inclination angle of 30 degrees. A useful formula to calculate the heat-transfer coefficient in the evaporator has been derived.

Negishi, K. (Tokyo Metropolitan Inst. of Technology (JP)); Kaneko, K. (Univ. of Osaka Prefecture (JP)); Matsuoka, T. (Nissan Motor Co., Ltd. (JP)); Hirashima, M.; Nishikawa, Y.; Taguchi, M. (Takuma Research and Development Co., Ltd. (JP))

1991-01-01

446

Shear Lag in Corrugated Sheets Used for the Chord Member of a Box Beam  

NASA Technical Reports Server (NTRS)

The problem of the distribution of normal stress across a wide corrugated sheet used as the chord of a box-beam-like structure is investigated theoretically and experimentally. Expressions are developed giving the stress distribution in beams, symmetrical or unsymmetrical, about a plane passed spanwise through the center of the sheet. The experiments were arranged to insure bending without torsion and surveys of the normal stresses were made by means of mechanical and electrical strain gages. The experimental data showed very good agreement with the new b of the theoretical curves, especially at the highly stressed sections, for both the symmetrical and unsymmetrical beams. Several suggestions for future research are included.

Newell, Joseph S; Reissner, Eric

1941-01-01

447

Analysis of Bonded Joints Between the Facesheet and Flange of Corrugated Composite Panels  

NASA Technical Reports Server (NTRS)

This paper outlines a method for the stress analysis of bonded composite corrugated panel facesheet to flange joints. The method relies on the existing HyperSizer Joints software, which analyzes the bonded joint, along with a beam analogy model that provides the necessary boundary loading conditions to the joint analysis. The method is capable of predicting the full multiaxial stress and strain fields within the flange to facesheet joint and thus can determine ply-level margins and evaluate delamination. Results comparing the method to NASTRAN finite element model stress fields are provided illustrating the accuracy of the method.

Yarrington, Phillip W.; Collier, Craig S.; Bednarcyk, Brett A.

2008-01-01

448

A multiscale spatial filtering account of the Wertheimer-Benary effect and the corrugated Mondrian.  

PubMed

Blakeslee and McCourt [Blakeslee, B., & McCourt, M.E. (1997). Similar mechanisms underlie simultaneous brightness contrast and grating induction. Vision Research, 37, 2849-2869] demonstrated that a multiscale array of two-dimensional difference-of-Gaussian (DOG) filters provided a simple but powerful model for explaining a number of seemingly complex features of grating induction (GI), while simultaneously encompassing salient features of brightness induction in simultaneous brightness contrast (SBC), brightness assimilation and Hermann Grid stimuli. The DOG model (and isotropic contrast models in general) cannot, however, account for another important group of brightness effects including the White effect [White, M. (1997). A new effect of pattern on perceived lightness. Perception, 8, 413-416] and a variant of SBC [Todorovic, D. (1997). Lightness and junctions. Perception, 26, 379-395]. Blakeslee and McCourt [Blakeslee, B., McCourt, M.E. (1999). A multiscale spatial filtering account of the White effect, simultaneous brightness contrast and grating induction. Vision Research, 39, 4361-4377] developed a modified version of the model, an oriented (ODOG) model, which differed from the DOG model in that the filters were anisotropic and their outputs were pooled nonlinearly. Using this model, they were able to account for both groups of induction effects. The present paper examines two additional sets of brightness illusions that cannot be explained by isotropic contrast models. Psychophysical brightness matching is employed to quantitatively measure the size of the brightness effect for two Wertheimer-Benary stimuli [Benary, W. (1924). Beobachtungen zu einem experiment uber helligkeitskontrast. Psychologische Forschung, 5, 131-142; Todorovic, D. (1997). Lightness and junctions. Perception, 26, 379-395] and for low- and high-contrast versions of corrugated Mondrian stimuli [Adelson, E.H. (1993). Perceptual organization and the jugdement of brightness. Science, 262, 2042-2044; Todorovic, D. (1997). Lightness and junctions. Perception, 26, 379-395]. Brightness matches are obtained on both homogeneous and checkerboard matching backgrounds. The ODOG model qualitatively predicts the appearance of the test patches in the Wertheimer-Benary stimuli and corrugated Mondrian stimuli. In addition, it quantitatively predicts the relative magnitudes of the corrugated Mondrian effects in the various conditions. In general, the psychophysical results and ODOG modeling argue strongly that like SBC, GI, the White effect and Todorovic's SBC demonstration, induced brightness in Wertheimer-Benary stimuli and in the corrugated Mondrian primarily reflects early-stage filtering operations in the visual system. PMID:11483179

Blakeslee, B; McCourt, M E

2001-09-01

449

Escape beam statistics and dynamical properties for a periodically corrugated waveguide  

NASA Astrophysics Data System (ADS)

Some escape and dynamical properties for a beam of light inside a corrugated waveguide are discussed by using Fresnel reflectance. The system is described by a mapping and is controlled by a parameter ? defining a transition from integrability (?=0) to non integrability (??0). The phase space is mixed containing periodic islands, chaotic seas and invariant tori. The histogram of escaping orbits is shown to be scaling invariant with respect to ?. The waveguide is immersed in a region with different refractive index. Different optical materials are used to overcame the results.

da Costa, Diogo Ricardo; Silva, Mário R.; Leonel, Edson D.

2014-04-01

450

Rotational corrugation in associative desorption of D2 from Cu(111)  

NASA Astrophysics Data System (ADS)

We report rotationally state-resolved measurements of the average steric orientation of D2 molecules desorbing from a Cu(111) surface. The desorbing flux of D2 molecules is probed by laser-induced fluorescence with linearly polarized tunable vacuum ultraviolet radiation in the B1?u+(v',J',M') <-- X1?g+(v'',J'',M''). Molecules desorbing in the vibrational ground state show for all rotational states measured (J'' = 1 - 8) a quadrupole alignment factor, A(2)0, compatible with a spatially isotropic distribution. A strong azimuthal, polar, and lateral corrugation of the dissociative interaction potential can cause this behavior.

Wetzig, D.; Rutkowski, M.; David, R.; Zacharias, H.

1996-10-01

451

Distributed-feedback terahertz quantum-cascade lasers with laterally corrugated metal waveguides  

NASA Astrophysics Data System (ADS)

We report the demonstration of distributed-feedback terahertz quantum-cascade lasers based on a first-order grating fabricated via a lateral corrugation in a double-sided metal ridge waveguide. The phase of the facet reflection was precisely set by lithographically defined facets by dry etching. Single-mode emission was observed at low to moderate injection currents, although multimode emission was observed far beyond threshold owing to spatial hole burning. Finite-element simulations were used to calculate the modal and threshold characteristics for these devices, with results in good agreement with experiments.

Williams, Benjamin S.; Kumar, Sushil; Hu, Qing; Reno, John L.

2005-11-01

452

Effects of asymmetric surface corrugations on fully metal-coated scanning near field optical microscopy tips.  

PubMed

We propose a new configuration for a fully metal coated scanning near field (SNOM) probe based on asymmetric corrugations in the metal coating. The variation in the metal surface induces coupling mechanisms leading to the creation of a localized hot spot under linearly polarized excitation. Field localization is an effect of paramount importance for resolution but cannot be achieved with standard axisymmetric fully metal-coated probes, unless a more cumbersome radially polarized excitation is used. Our simulations show that this promising structure allows one to simplify the mode injection procedures circumventing the need for a radially polarized beam. PMID:20588716

Lotito, Valeria; Sennhauser, Urs; Hafner, Christian

2010-04-12

453

46 CFR 182.455 - Fuel piping.  

Code of Federal Regulations, 2010 CFR

...thickness of 0.9 millimeters (0.035 inch) except that: (i) Diesel fuel piping of other materials, such as seamless steel pipe or tubing, which provide equivalent safety may be used; (ii) Diesel fuel piping of aluminum is...

2010-10-01

454

Cold Drawn ERW Pipes with Superior Formability,  

National Technical Information Service (NTIS)

Cold drawn ERW pipes have been applied in various fields. Cold drawn pipes show recrystallized microstructures when they are annealed for softening. Cold drawn ERW pipes sometimes show a difficulty in formability during cold working of expanding, swaging ...

T. Adaniya T. Takamura T. Meada F. Nishimura M. Morimoto

1988-01-01

455

Ceramic heat pipe wick  

NASA Technical Reports Server (NTRS)

A wick for use in a capillary loop pump heat pipe is disclosed. The wick material is an essentially uniformly porous, permeable, open-cell, silicon dioxide/aluminum oxide inorganic ceramic foam having a silica fiber ratio, by weight, of about 78 to 22, respectively, a density of 6 lbs/cu ft, and an average pore size of less than 5 microns. A representative material having these characteristics is Lockheed Missile and Space Company, Inc.'s HTP 6-22. This material is fully compatible with the freons and anhydrous ammonia and allows for the use of these very efficient working fluids, and others, in capillary loops.

Seidenberg, Benjamin (inventor); Swanson, Theodore (inventor)

1989-01-01

456

Polymeric heat pipe wick  

NASA Astrophysics Data System (ADS)

A wick for use in a capillary loop pump heat pipe is described. The wick material is an essentially uniformly porous, permeable, open-cell, polyethylene thermoplastic foam having an ultrahigh average molecular weight of from approximately 1 to 5 million, and an average pore size of about 10 to 12 microns. A representative material having these characteristics is POREX UF, which has an average molecular weight of about 3 million. This material is fully compatible with the FREONs and anhydrous ammonia and allows for the use of these very efficient working fluids in capillary loops.

Seidenberg, Benjamin

1988-08-01

457

Dispersion relation and growth rate for a corrugated channel free-electron laser with a helical wiggler pump  

NASA Astrophysics Data System (ADS)

The effects of corrugated ion channels on electron trajectories and spatial growth rate for a free-electron laser with a one-dimensional helical wiggler have been investigated. Analysis of the steady-state electron trajectories is performed by solving the equations of motion. Our results show that the presence of a corrugated channel shifts the resonance frequency to smaller values of ion channel frequency. The sixth-order dispersion equation describing the coupling between the electrostatic beam mode and the electromagnetic mode has also been derived. The dispersion relation characteristic is analyzed in detail by numerical solution. Results show that the growth rate of instability in the presence of corrugated ion channels can be greatly enhanced relative to the case of an uniform ion channel.

Hasanbeigi, A.; Mehdian, H.

2013-07-01

458

Demonstrating Sound Impulses in Pipes.  

ERIC Educational Resources Information Center

Describes a simple, direct method to demonstrate the effects of the boundary conditions on sound impulse reflections in pipes. A graphical display of the results can be made using a pipe, cork, small hammer, microphone, and fast recording electronics. Explains the principles involved. (LZ)

Raymer, M. G.; Micklavzina, Stan

1995-01-01

459

Building a Copper Pipe "Xylophone."  

ERIC Educational Resources Information Center

Explains how to use the equation for frequency of vibration of a transversely oscillating bar or pipe with both ends free to vibrate to build a simple and inexpensive xylophone from a 3-meter section of copper pipe. The instrument produces a full major scale and can be used to investigate various musical intervals. (Author/NB)

Lapp, David R.

2003-01-01

460

SRP reactor moderator piping inspections  

SciTech Connect

A program has been planned and initiated to provide inspection of SRP reactor moderator piping for intergranular stress corrosion cracking. Inspections will be accomplished by SRP personnel and subcontractors, using state of the art inspection techniques and equipment. Computerized ultransonic inspection systems are being evaluated on R-Area piping. A related program is in progress to determine acceptance criteria for inspection results.

Sprayberry, R.E.

1984-01-01

461

SRP reactor moderator piping inspections  

Microsoft Academic Search

A program has been planned and initiated to provide inspection of SRP reactor moderator piping for intergranular stress corrosion cracking. Inspections will be accomplished by SRP personnel and subcontractors, using state of the art inspection techniques and equipment. Computerized ultransonic inspection systems are being evaluated on R-Area piping. A related program is in progress to determine acceptance criteria for inspection

Sprayberry

1984-01-01

462

Closed loop pulsating heat pipes  

Microsoft Academic Search

Closed loop pulsating heat pipes (CLPHPs) are complex heat transfer devices having a strong thermo-hydrodynamic coupling governing the thermal performance. In this paper, a wide range of pulsating heat pipes is experimentally studied thereby providing vital information on the parameter dependency of their thermal performance. The influence characterization has been done for the variation of internal diameter, number of turns,

Piyanun Charoensawan; Sameer Khandekar; Manfred Groll; Pradit Terdtoon

2003-01-01

463

Physical principles of heat pipes  

Microsoft Academic Search

Heat pipes are used whenever high rates of heat transfer or the control or conversion of heat flows are required. This book covers the physical principles of operation of heat pipes and choice of working fluid related to temperature range. The authors demonstrate how performance is limited by capillary pumping action in the wick together with impedance to liquid and

M. N. Ivanovskii; V. P. Sorokin; I. V. Yagodkin

1982-01-01

464

Heat-Pipe Wick Characterization.  

National Technical Information Service (NTIS)

The development of liquid metal heat-pipes for use in solar powered Stirling engines has led to an in-depth analysis of heat-pipe wick properties. To model the flow of liquid sodium through the wick its two-phase permeability measurement is of interest. T...

J. L. Jones

2000-01-01

465

Alternate high capacity heat pipe  

NASA Technical Reports Server (NTRS)

The performance predictions for a fifty foot heat pipe (4 foot evaporator - 46 foot condensor) are discussed. These performance predictions are supported by experimental data for a four foot heat pipe. Both heat pipes have evaporators with axial groove wick structures and condensers with powder metal external artery wick structures. The predicted performance of a rectangular axial groove/external artery heat pipe operating in space is given. Heat transport versus groove width is plotted for 100, 200 and 300 grooves in the evaporator. The curves show that maximum power is achieved for groove widths from 0.040 to 0.053 as the number of grooves varies from 300 to 100. The corresponding range of maximum power is 3150 to 2400 watts. The relationships between groove width and heat pipe evaporate diameter for 100, 200 and 300 grooves in the evaporator are given. A four foot heat pipe having a three foot condenser and one foot evaporator was built and tested. The evaporator wick structure used axial grooves with rectangular cross sections, and the condenser wick structure used powder metal with an external artery configuration. Fabrication drawings are enclosed. The predicted and measured performance for this heat pipe is shown. The agreement between predicted and measured performance is good and therefore substantiates the predicted performance for a fifty foot heat pipe.

Voss, F. E.

1986-01-01

466

Pipe laying apparatus and method  

Microsoft Academic Search

Apparatus and method are described for laying a pipeline on the bottom of an ocean wherein a wheel-like, buoyant body is adapted to carry a single, continuous length of pipe in the form of horizontal convolutions from a first site at which the pipe is wrapped on the body to a second site where the convolutions are moved into vertical

F. S. Ellers; N. R. Wallace

1981-01-01

467

Pipe crawler with stabilizing midsection  

SciTech Connect

This invention is comprised of a pipe crawler having a midsection that provides the stability and flexibility to allow the pipe crawler to negotiate curved and uneven segments of piping while traveling through piping systems. The pipe crawler comprises a front leg assembly, a rear leg assembly, a midsection with a gimbal at each end for connecting the midsection to the front and rear leg assemblies in a flexible manner, and an air cylinder for changing the distance between the front and rear leg assemblies. The pipe crawler moves in ``inch worm`` fashion with the front and rear leg assemblies alternating between an extended and a retracted position as the air cylinder moves the retracted leg assembly forward. The midsection has a plurality of legs extending radially for holding the midsection within a maximum displacement from the piping axis so that the gimbals are not pivoted to extreme angles where they might lock up or seize. When the midsection is displaced sufficiently, its legs with wheels on each end engage the interior surface of the piping and prevent further displacement. Using two gimbals divides the angle between the planes defined by the front and rear leg assemblies which also helps to prevent excessive gimbal pivoting.

Zollinger, W.T.; Treanor, R.C.

1993-09-20

468

Alternate high capacity heat pipe  

NASA Astrophysics Data System (ADS)

The performance predictions for a fifty foot heat pipe (4 foot evaporator - 46 foot condensor) are discussed. These performance predictions are supported by experimental data for a four foot heat pipe. Both heat pipes have evaporators with axial groove wick structures and condensers with powder metal external artery wick structures. The predicted performance of a rectangular axial groove/external artery heat pipe operating in space is given. Heat transport versus groove width is plotted for 100, 200 and 300 grooves in the evaporator. The curves show that maximum power is achieved for groove widths from 0.040 to 0.053 as the number of grooves varies from 300 to 100. The corresponding range of maximum power is 3150 to 2400 watts. The relationships between groove width and heat pipe evaporate diameter for 100, 200 and 300 grooves in the evaporator are given. A four foot heat pipe having a three foot condenser and one foot evaporator was built and tested. The evaporator wick structure used axial grooves with rectangular cross sections, and the condenser wick structure used powder metal with an external artery configuration. Fabrication drawings are enclosed. The predicted and measured performance for this heat pipe is shown. The agreement between predicted and measured performance is good and therefore substantiates the predicted performance for a fifty foot heat pipe.

Voss, F. E.

1986-10-01

469

Pipe crawler with stabilizing midsection  

DOEpatents

A pipe crawler is described having a midsection that provides the stability and flexibility to allow the pipe crawler to negotiate curved and uneven segments of piping while traveling through piping systems. The pipe crawler comprises a front leg assembly, a rear leg assembly, a midsection with a gimbal at each end for connecting the midsection to the front and rear leg assemblies in a flexible manner, and an air cylinder for changing the distance between the front and rear leg assemblies. The pipe crawler moves in ''inch worm'' fashion with the front and rear leg assemblies alternating between an extended and a retracted position as the air cylinder moves the retracted leg assembly forward. The midsection has a plurality of legs extending radially for holding the midsection within a maximum displacement from the piping axis so that the gimbals are not pivoted to extreme angles where they might lock up or seize. When the midsection is displaced sufficiently, its legs with wheels on each end engage the interior surface of the piping and prevent further displacement. Using two gimbals divides the angle between the planes defined by the front and rear leg assemblies which also helps to prevent excessive gimbal pivoting. 5 figures.

Zollinger, W.T.; Treanor, R.C.

1994-12-27

470

Vapor spill pipe monitor  

DOEpatents

The invention is a method and apparatus for continually monitoring the composition of liquefied natural gas flowing from a spill pipe during a spill test by continually removing a sample of the LNG by means of a probe, gasifying the LNG in the probe, and sending the vaporized LNG to a remote ir gas detector for analysis. The probe comprises three spaced concentric tubes surrounded by a water jacket which communicates with a flow channel defined between the inner and middle, and middle and outer tubes. The inner tube is connected to a pump for providing suction, and the probe is positioned in the LNG flow below the spill pipe with the tip oriented partly downward so that LNG is continuously drawn into the inner tube through a small orifice. The probe is made of a high thermal conductivity metal. Hot water is flowed through the water jacket and through the flow channel between the three tubes to provide the necessary heat transfer to flash vaporize the LNG passing through the inner channel of the probe. The gasified LNG is transported through a connected hose or tubing extending from the probe to a remote ir sensor which measures the gas composition.

Bianchini, G.M.; McRae, T.G.

1983-06-23

471

E-plane radiation pattern analysis of rectangular horn antennas with V-shaped corrugations by UTD-PO formulation  

NASA Astrophysics Data System (ADS)

A new method for the calculation of the radiation pattern of corrugated E-plane rectangular horn antennas based on a hybrid uniform theory of diffraction-physical optics (UTD-PO) formulation is presented. The method, which allows for the analysis of horns in which V-shaped corrugations have been considered, has been validated with numerical data obtained through the application of both an electric field integral equation (EFIE) solved by the method of moments (MoM) and the finite element method (FEM)-based full-wave electromagnetic analysis software, HFSS. In this sense, the proposed solution is mathematically less complex and computationally more efficient than existing techniques.

RodríGuez, José-VíCtor; Quesada-Pereira, Fernando; Juan-LláCer, Leandro; Verdú-RodríGuez, Elisa; Molina-GarcíA-Pardo, José-MaríA.; ÁLvarez-Melcón, Alejandro

2012-01-01

472

Geothermal district piping - A primer  

SciTech Connect

Transmission and distribution piping constitutes approximately 40 -60% of the capital costs of typical geothermal district heating systems. Selections of economical piping suitable for the fluid chemistry is critical. Presently, most piping (56%) in geothermal systems is of asbestos cement construction. Some fiberglass (19%) and steel (19%) is also in use. Identification of an economical material to replace asbestos cement is important to future project development. By providing information on relative costs, purchase considerations, existing material performance and new products, this report seeks to provide a background of information to the potential pipe purchaser. A brief discussion of the use of uninsulated piping in geothermal district heating systems is also provided. 5 refs., 19 figs., 1 tab.

Rafferty, K.

1989-11-01

473

Flexible ultrasonic pipe inspection apparatus  

DOEpatents

A flexible, modular ultrasonic pipe inspection apparatus, comprising a flexible, hollow shaft that carries a plurality of modules, including at least one rotatable ultrasonic transducer, a motor/gear unit, and a position/signal encoder. The modules are connected by flexible knuckle joints that allow each module of the apparatus to change its relative orientation with respect to a neighboring module, while the shaft protects electrical wiring from kinking or buckling while the apparatus moves around a tight corner. The apparatus is moved through a pipe by any suitable means, including a tether or drawstring attached to the nose or tail, differential hydraulic pressure, or a pipe pig. The rotational speed of the ultrasonic transducer and the forward velocity of the apparatus are coordinated so that the beam sweeps out the entire interior surface of the pipe, enabling the operator to accurately assess the condition of the pipe wall and determine whether or not leak-prone corrosion damage is present.

Jenkins, Charles F. (Aiken, SC); Howard, Boyd D. (Augusta, GA)

1998-01-01

474

Promethus Hot Leg Piping Concept  

SciTech Connect

The Naval Reactors Prime Contractor Team (NRPCT) recommended the development of a gas cooled reactor directly coupled to a Brayton energy conversion system as the Space Nuclear Power Plant (SNPP) for NASA's Project Prometheus. The section of piping between the reactor outlet and turbine inlet, designated as the hot leg piping, required unique design features to allow the use of a nickel superalloy rather than a refractory metal as the pressure boundary. The NRPCT evaluated a variety of hot leg piping concepts for performance relative to SNPP system parameters, manufacturability, material considerations, and comparison to past high temperature gas reactor (HTGR) practice. Manufacturability challenges and the impact of pressure drop and turbine entrance temperature reduction on cycle efficiency were discriminators between the piping concepts. This paper summarizes the NRPCT hot leg piping evaluation, presents the concept recommended, and summarizes developmental issues for the recommended concept.

AM Girbik; PA Dilorenzo

2006-01-24

475

D0 Silicon Upgrade: Upgrade Piping Loads on Cleanroom Roof  

SciTech Connect

The proposed piping layout for the DO upgrade will run along the south wall of DAB. The cryogenic service pipe runs above the upper and lower cleanroom roofs and will need to be supported by the roofs beams. Calculations were done to determine the stresses in the I-beams created by the existing and additional loads due to the upgrade. Refer to drawing no. 3823.115-ME-317283 for drawings of the piping layout. Figure 1 shows the 'plan view' portion of this drawing. The weight of the individual lines were calculated in figure 2 assuming a pipe density of O.28 lbm/in{sup 3} for stainless steel (0.12% C) and a fluid density (assuming LN2 at 1 atm) of 0.03 lbm/in{sup 3}. The weights of the corrugated steel flooring, assembly hall feed cans, support beams, and roof hatch were also included in the analysis. These loads are calculated on pgs. 5-6. A floor load of 50 lbf/ft{sup 2} was also added in order to maintain the existing floor load limit in addition to the added piping loads. Measurements of the dimensions of the I-beams determined that the nominal sizes of the beams were W8 x 21 for the lower roof and W14 x 26 for the upper roof. Pipe lengths were determined from the drawing for each of the lines on pgs. 1-2 of the calculations (refer to all piping by line numbers according to figure 2). A total weight was calculated for lines 3-9 along the south wall and lines 1-2 running along the north wall of the lower cleanroom roof. To simplify the calculations these weights were assumed to be evenly distributed on the 5 I-beam supports of the lower cleanroom roof 2.5 feet in from the south wall. The stress analysis was done using FrameMac, a 2-D finite element program for the Macintosh. Beam 3 was not included in the analysis because it is structurally equivalent to beam 1. The program outputted maximum values for shear stress, bending stress, shear force, and moments in each of the beams analyzed. These values were then compared to the allowable stresses as per the specifications and codes stated in the AISC: Manual of Steel Construction. The stresses on the roof beams needed to be determined in a number of different places. The first was in the beam itself which included the flange and web sections. The second place was at the ends of the beams where the flanges were removed to make the perpendicular connections to the other beams on the lower roof. The final point was the framed beam connection which included the bolt analysis. FrameMac calculated stresses only for the beams which included the sections where the flanges were removed to make the end connections. To analyze the connections, the allowable bending and shear stresses were solved for allowable shear and moments. This was done because FrameMac does not have the capability to analyze the dimensions for the bolts and angles used in the connections were known and the program outputted values for reaction forces and moments at the ends of the beams. Multiplying the allowable shear stress for the bolts and angle connections by their respective areas gave the allowable shear force. The allowable moment for the angle connection was calculated by multiplying the section modulus of the angle by the allowable bending stress. These allowable loads are calculated on pgs. 7-8. The allowable and maximum calculated stresses by FrameMac are summarized in a table. In conclusion, the cleanroom roofs will be able to safely support the weight of the upgrade cryogenic piping, feed cans, corrugated flooring and a 50 lbf/ft{sup 2} floor load with the addition of diagonal braces at the ends of beams 1,2,3,4, and 8. The location and size of these diagonal braces are shown in fig. 4. Also, the piping supports and feed cans will all need to be placed directly above the I-beam supports. These supports will consist of unistrut structures that will be detailed and specified separate to this analysis. The output and input data from FrameMac and the drawings used in the analysis follow the calculation pages.

Sakla, Steve; /Fermilab

1995-08-28

476

Finite element modelling of surface acoustic wave device based corrugated microdiaphragms  

NASA Astrophysics Data System (ADS)

This paper presents modelling and analysis of microdiaphragms that are designed for implantable micropump applications. Microdiaphragms are considered to be a major component of micropumps. A securely operated, electrostatically actuated, fully passive micropump is designed using a novel method, which is based on surface acoustic wave (SAW) devices and wireless transcutaneous radio frequency (RF) communication. The device is capable of extracting the required power from the RF signal itself, like RFID (ID: identification device) tags; hence the need of a battery and active electronics is negated. Moreover, a SAW correlator is used for secure interrogation of the device. As a result, the device responds only to a unique RF signal, which has the same code as was implanted in the SAW correlator. Finite element analysis (FEA) based on code from ANSYS Inc. is carried out to model the microdiaphragm, and a Rayleigh-Ritz method based analytical model is developed to investigate the validity of the FEA results. During the FEA, a three-dimensional model of the diaphragm is developed and various kinds of corrugation profiles are considered for enhancing the device performance. A coupled-field analysis is carried out to model the electrostatics-solid interaction between the corrugated microdiaphragm and the SAW device. In modelling microdiaphragms, selection of appropriate material properties and element types, application of accurate constraints, and selection of suitable mesh parameters are carefully considered.

Dissanayake, Don W.; Al-Sarawi, Said; Lu, Tien-Fu; Abbott, Derek

2009-09-01

477

High-efficiency wideband gyro-TWTs and gyro-BWOs with helically corrugated waveguides  

NASA Astrophysics Data System (ADS)

We review the studies of gyrotron-type microwave devices whose electrodynamic system has the form of an oversized metal waveguide with a helically corrugated internal surface. For certain parameters, such a corrugation changes radically the waveguide dispersion ensuring an almost constant group velocity of the eigenmode for a small (close to zero) longitudinal wave number in a wide frequency band. The use of “helical” waveguides along with electron optical systems which form near-axis electron beams makes it possible to create high-efficiency amplifiers based on gyro-traveling-wave tubes (gyro-TWTs) with a wide instantaneous frequency band of amplification and gyro-backward-wave oscillators (gyro-BWOs) with continuous wideband tuning of the oscillation frequency. The studied devices are superior to the well-studied microwave sources of this type (gyroklystrons and gyrotrons) in frequency band, by more than an order of magnitude, and are not inferior to them in efficiency even for a wide spread of electron velocities.

Bratman, V. L.; Denisov, G. G.; Samsonov, S. V.; Cross, A. W.; Phelps, A. D. R.; Xe, W.

2007-02-01

478

Effect of support corrugation on silica xerogel--supported phase-separated lipid bilayers.  

PubMed

Lipid bilayers supported by substrates with nanometer-scale surface corrugations hold interest in understanding both nanoparticle-membrane interactions and the challenges of constructing models of cell membranes on surfaces with desirable properties, e.g., porosity. Here, we successfully form a two-phase (gel-fluid) lipid bilayer supported by nanoporous silica xerogel. Surface topology, lateral diffusion coefficient, and lipid density in comparison to mica-supported lipid bilayers were characterized by atomic force microscopy, fluorescence recovery after photobleaching (FRAP), fluorescence correlation spectroscopy (FCS), and quantitative fluorescence microscopy, respectively. We found that the two-phase lipid bilayer follows the silica xerogel surface contours. The corrugation imparted on the lipid bilayer results in a lipid density that is twice that on a flat mica surface in the fluid regions. In direct agreement with the doubling of actual bilayer area in a projected area, we find that the lateral diffusion coefficient (D) of fluid lipids on silica xerogel (approximately 1.7 microm2/s) is lower than on mica (approximately 3.9 microm2/s) by both FRAP and FCS techniques. Furthermore, the gel-phase domains on silica xerogel compared to mica were larger and less numerous. Overall, our results suggest the presence of a relatively defect-free continuous two-phase lipid bilayer that penetrates approximately midway into the first layer of approximately 50 nm silica xerogel beads. PMID:19708250

Goksu, Emel I; Nellis, Barbara A; Lin, Wan-Chen; Satcher, Joe H; Groves, Jay T; Risbud, Subhash H; Longo, Marjorie L

2009-04-01

479

Rectified brownian transport in corrugated channels: Fractional brownian motion and Le?vy flights.  

PubMed

We study fractional brownian motion and Le?vy flights in periodic corrugated channels without any external driving forces. From numerical simulations, we find that both fractional gaussian noise and Le?vy-stable noise in asymmetric corrugated channels can break thermodynamical equilibrium and induce directed transport. The rectified mechanisms for fractional brownian motion and Le?vy flights are different. The former is caused by non-uniform spectral distribution (low or high frequencies) of fractional gaussian noise, while the latter is due to the nonthermal character (occasional long jumps) of the Le?vy-stable noise. For fractional brownian motion, average velocity increases with the Hurst exponent for the persistent case, while for the antipersistent case there exists an optimal value of Hurst exponent at which average velocity takes its maximal value. For Le?vy flights, the group velocity decreases monotonically as the Le?vy index increases. In addition, for both cases, the optimized periodicity and radius at the bottleneck can facilitate the directed transport. Our results could be implemented in constrained structures with narrow channels and pores where the particles undergo anomalous diffusion. PMID:23145711

Ai, Bao-quan; Shao, Zhi-gang; Zhong, Wei-rong

2012-11-01

480

Study of the effects of corrugated wall structures due to blanket modules around ICRH antennas  

NASA Astrophysics Data System (ADS)

In future fusion reactors, and in ITER, the first wall will be covered by blanket modules. These blanket modules, whose dimensions are of the order of the ICRF wavelengths, together with the clearance gaps between them will constitute a corrugated structure which will interact with the electromagnetic waves launched by ICRF antennas. The conditions in which the grooves constituted by the clearance gaps between the blanket modules can become resonant are studied. Simple analytical models and numerical simulations show that mushroom type structures (with larger gaps at the back than at the front) can bring down the resonance frequencies, which could lead to large voltages in the gaps between the blanket modules and perturb the RF properties of the antenna if they are in the ICRF operating range. The effect on the wave propagation along the wall structure, which is acting as a spatially periodic (toroidally and poloidally) corrugated structure, and hence constitutes a slow wave structure modifying the wall boundary condition, is examined.

Dumortier, Pierre; Louche, Fabrice; Messiaen, André; Vervier, Michel

2014-02-01

481

Nanophase coexistence and sieving in binary mixtures confined between corrugated walls  

SciTech Connect

The grand canonical Monte Carlo method is used to study a binary mixture of Lennard-Jones atoms confined to a corrugated slit micropore which is in thermodynamic equilibrium with its bulk phase counterpart. The micropore has atomically structured walls; one of the which possesses nanoscale structure in the form of rectilinear grooves (corrugation). The grooved surface divides the confined fluid film into two strip shaped regions, that inside and that outside the grooves. Transverse solidlike order in the film gives rise to shear stress. Transverse order coupled with packing restrictions give rise to a difference between the pore and bulk fluid mixture compositions. Solidlike order may appear within the grooves only, outside the grooves only, or in both regions simultaneously. As the relative alignment of the walls is shifted the pore fluid undergoes freeze--thaw cycles in one or both regions with associated changes in the shear stress and pore fluid composition. The degree of transverse order in the film is less than would be expected in a pure Lennard-Jones film and fluid-solid phase transitions are gradual as opposed to sudden as seen in pure Lennard-Jones films. The magnitude of the shear stress is greatest when a fluid--solid phase transition occurs in both regions of the pore. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.

Curry, J.E.; Cushman, J.H. [Center for Applied Mathematics, Math Sciences Building, Purdue University, West Lafayette, Indiana 47907 (United States)] [Center for Applied Mathematics, Math Sciences Building, Purdue University, West Lafayette, Indiana 47907 (United States)

1995-08-08

482

The corrugation of the electronic surface of Pt( 1 1 0 ) observed by surface channeling  

NASA Astrophysics Data System (ADS)

Surface channeling experiments at different energies are used to evaluate inelastic losses. Over a wide range of energies, from 1 keV to 2 MeV, the inelastic losses can be explained consistently with theory based on the density functional ansatz. The data for random surface directions need one parameter, zedge, only. The parameter zedge is an average measure for the decay of the electron density at the surface with respect to the dielectric function. Experiments along the surface channels of the (1 1 0) surface and variation of the azimuthal angle with respect to these directions reveal many new features. The ion energy loss spectra split up into several peaks which can be identified being due to different trajectories. The interpretation of the results based on the density functional theory energy loss data show that the zedge follows laterally the corrugated electronic surface. This corrugation does not coincide with the surface defined by the turning points of the trajectories, i.e. the 'elastic potential surface'.

Heiland, Werner; Robin, Abel

2003-04-01

483

Simple Correctors for Elimination of High-Order Modes in Corrugated Waveguide Transmission Lines  

PubMed Central

When using overmoded corrugated waveguide transmission lines for high power applications, it is necessary to control the mode content of the system. Ideally, overmoded corrugated transmission lines operate in the fundamental HE11 mode and provide low losses for long distances. Unwanted higher order modes (HOMs), particularly LP11 and HE12, are often excited in the experimental systems due to practical misalignments in the transmission line system. This paper discusses how the unwanted modes propagate along with the fundamental mode in the transmission line system by formulating an equation that relates the center of power offset and angle of propagation of a beam (for the HE11 and LP11 modes) or the waist size and phase front radius of curvature of a beam (for the HE11 and HE12 modes). By introducing two miter bend correctors into the transmission system—miter bends that have slightly angled or ellipsoidal mirrors—the HOMs can be precisely manipulated in the system. This technique can be used to eliminate small quantities of unwanted modes, thereby creating a nearly pure fundamental mode beam with minimal losses. Examples of these applications are calculated and show the theoretical conversion of up to 10% HOM content into the fundamental HE11 mode with minimal losses.

Kowalski, Elizabeth J.; Shapiro, Michael A.; Temkin, Richard J.

2014-01-01

484

Solution of Helmholtz's equation in multilayered dielectric waveguide with periodic surface corrugation  

NASA Astrophysics Data System (ADS)

Dielectric waveguide with periodic surface corrugation are used in distributed feedback lasers and DBR lasers. In this paper the boundary element method (BEM) has been used to analyze 2D dielectric periodic corrugated waveguides. It is a very efficient method for analysis of this type of structure. The computational method relies on the numerical solution of the integral wave equation inside the grating region. This formalism has distinct advantages over the more traditional ones, especially when the boundary conditions are imposed through a collocation (point-matching) technique. The unknown field quantities together with all the boundary conditions of the problem are explicitly incorporated in the defining equation. For the problem at hand, the boundary conditions on the longitudinal interfaces of the grating layer are functionally known because of the Floquet expansion of the fields in the uniform layers above and below it. On the other hand, the boundary conditions for the interface between the periodic unit cells are naturally provided by Floquet's theorem and continuity requirements. Thus the method can be applied in a rather straightforward way towards a rigorous solution of the periodic problem, without any a priori assumptions, within a user specified accuracy. The BEM is a natural choice for this problem because we seek the field solution only on the grating layer interfaces in order to set up a transverse resonant-type characteristic equation for propagating mode. In this paper electromagnetic field and coupling coefficient for multi- layer dielectric waveguide is calculated.

Mossallaei, Hossein; Abiri, Habibollah; Rahnavard, Mohammad H.; Zomorrodi, Mehrdad

1999-05-01

485

Variable conductance heat pipe technology  

NASA Technical Reports Server (NTRS)

Research and development programs in variable conductance heat pipe technology were conducted. The treatment has been comprehensive, involving theoretical and/or experimental studies in hydrostatics, hydrodynamics, heat transfer into and out of the pipe, fluid selection, and materials compatibility, in addition to the principal subject of variable conductance control techniques. Efforts were not limited to analytical work and laboratory experimentation, but extended to the development, fabrication and test of spacecraft hardware, culminating in the successful flight of the Ames Heat Pipe Experiment on the OAO-C spacecraft.

Marcus, B. D.; Edwards, D. K.; Anderson, W. T.

1973-01-01

486

Heat treatment of fluid foods in a shell and tube heat exchanger: Comparison between smooth and helically corrugated wall tubes  

Microsoft Academic Search

Fluid foods are often subjected to thermal treatment inside surface heat exchangers. Besides the need for high heat transfer performance, also low friction losses and easy cleaning and sanitizing properties of the surface are imperative. In food process industry these requirements are often met by the shell and tube heat exchanger equipped with helically corrugated walls.The present work concerns convective

S. Rozzi; R. Massini; G. Paciello; G. Pagliarini; S. Rainieri; A. Trifirò

2007-01-01

487

A multi-objective approach based on soft computing techniques for production scheduling in Corrugator manufacturing plants  

Microsoft Academic Search

The corrugator scheduling problem is a difficult problem due to a wide variety of parameters and optimisation objectives that have to be accounted for and the relationships among them. Majority of solution techniques proposed so far only deal with minimizing either, the trim waste or pattern changes, this paper proposes a multi-objective evolutionary algorithm to optimize the WPL objective (weighted

Germán A. Velásquez; Gisella Bellini; Carlos D. Paternina-Arboleda

2007-01-01

488

Heat exchange pipes for a furnace system  

Microsoft Academic Search

This patent describes improvement in a flue products exhaust and preheated combustion air supply assembly for use in association with a heating furnace wherein an air intake pipe is provided outside of and around an exhaust product pipe and wherein each of the pipes extend horizontally to openings outside of a building. It comprises: an air intake pipe and exhaust

1991-01-01

489

Flexible PMMA pipe for terahertz propagation  

NASA Astrophysics Data System (ADS)

We present an experimental study on a flexible terahertz (THz) pipe PMMA waveguide. The attenuation loss of this pipe at 3.1THz was 9.65dB/m. Further more, bending loss of the pipe waveguides was investigated. The experimental result shows good transmission properties of the pipe.

Liu, Jing; Xiao, Mingfei; Shen, Jingling; Zhang, Wei

2012-12-01

490

Heat pipes for industrial waste heat recovery  

Microsoft Academic Search

Development work on the high temperature ceramic recuperator at Los Alamos National Laboratory is described and involved material investigations, fabrication methods development, compatibility tests, heat pipe operation, and the modeling of application conditions based on current industrial usage. Solid ceramic heat pipes, ceramic coated refractory pipes, and high-temperature oxide protected metallic pipes are investigated. Economic studies of the use of

M. A. Merrigan

1981-01-01

491

Heat pipe technology: A bibliography with abstracts  

NASA Technical Reports Server (NTRS)

A cumulative bibliography on heat pipe research and development projects is presented. The subjects discussed are: (1) general information, (2) heat pipe applications, (3) heat pipe theory, (4) design and fabrication, (5) testing and operation, (6) subject and author index, and (7) heat pipe related patents.

1971-01-01

492

The Sacred Pipe in American Indian Religions.  

ERIC Educational Resources Information Center

A bibliographic essay covers all significant literature on the Sacred Pipe among the North American tribes. Organizes over 130 references dating from 1843 to 1980 under topics such as American Indian attitudes toward the pipe, sacramental and ceremonial uses of the pipe, and the pipe as symbolic man. (JHZ)

Steinmetz, Paul B.

1984-01-01

493

Laboratory Load Tests on Buried Flexible Pipe.  

National Technical Information Service (NTIS)

As part of a study on soil factors affecting the behavior of buried pipe, research is being conducted on the soil-structure interaction of buried flexible pipe; earlier tests dealt with rigid pipe. The main items of investigation on flexible pipe are soil...

A. K. Howard

1968-01-01

494

Heat pipe technology: A biblography with abstracts  

NASA Technical Reports Server (NTRS)

A bibliography of heat pipe research and development projects conducted during April through June 1972, is presented. The subjects discussed are: (1) general information, (2) heat pipe applications, (3) heat pipe theory, (4) design and fabrication, (5) test and operation, (6) subject and author index, and (7) heat pipe related patents.

1972-01-01