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Wednesday, April 22, 2020 | History

3 edition of Thermal smoothing of rough surfaces in vacuo found in the catalog.

Thermal smoothing of rough surfaces in vacuo

Georg Wahl

Thermal smoothing of rough surfaces in vacuo

  • 318 Want to read
  • 20 Currently reading

Published by National Aeronautics and Space Administration, National Technical Information Service, distributor in Washington, DC, [Springfield, Va .
Written in English

    Subjects:
  • Interfacial tension.,
  • Mathematical models.,
  • Metals.,
  • Smoothing.,
  • Surface roughness.,
  • Temperature effects.,
  • Thermodynamics.

  • Edition Notes

    StatementGeorg Wahl.
    SeriesNASA technical memorandum -- NASA TM-88425, NASA technical memorandum -- 88425..
    ContributionsUnited States. National Aeronautics and Space Administration.
    The Physical Object
    FormatMicroform
    Pagination1 v.
    ID Numbers
    Open LibraryOL17115468M

    A fundamental problem in analyzing and predicting junction thermal conductance is determining thermal contact conductance of nonflat rough metals. Workable models have been previously derived for the limiting idealized cases of flat, rough, and spherical smooth by: Evaporation is a common method of thin-film deposition. The source material is evaporated in a vacuum. The vacuum allows vapor particles to travel directly to the target object (substrate), where they condense back to a solid state. Evaporation is used in microfabrication, and to make macro-scale products such as metallized plastic film. A black body or blackbody is an idealized physical body that absorbs all incident electromagnetic radiation, regardless of frequency or angle of incidence. (It does not only absorb radiation, but can also emit radiation. The name "black body" is given because it absorbs radiation in all frequencies, not because it only absorbs.) A white body is one with a "rough surface that . Start studying Rocks & Minerals. Learn vocabulary, terms, and more with flashcards, games, and other study tools. Search. Browse. Igneous rock formed from the cooling of lava on the earth's surface. Strata. Layers of rocks. Stratification. The layering of rocks. The rough texture of a rock. Fine Grained. The smooth texture of a rock.


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Thermal smoothing of rough surfaces in vacuo by Georg Wahl Download PDF EPUB FB2

Get this from a library. Thermal smoothing of rough surfaces in vacuo. [Georg Wahl; United States. Thermal smoothing of rough surfaces in vacuo book National Aeronautics and Space Administration.]. Purchase Thermal Design Principles of Spacecraft and Entry Bodies - 1st Edition.

Print Book & E-Book. ISBNBook Edition: 1. The detection of subsurface structure in opaque and als by thermal waves has been widely reported over the past decade for fatigue cracks, subsurface channels, drilled holes, spherical and disc-shaped air-filled defects and partially bonded surface coatings /1,2/.Cited by: 1.

Contact thermal resistance of machined metal surfaces in vacuo. Abstract. The paper presents the results of an experimental investigation of contact thermal resistances of stainless steel and molybdenum samples for the range of compressive loads between and 58 10 −5 N/m 2 and for an absolute pressure of the surrounding medium of 10 −4 mm : V.

Mal'kov. One should be very careful with the reconstruction of the rough surfaces to ensure the two surfaces have the same relative position with that of experimental conditions, i.e., typical regions like R 1 and R 2 of the lower surface are corresponding to the R 1 ’ and R 2 ’ regions of the upper surface as shown in Figs.

2 and 3, by: Thus, if this smooth tube is replaced by a rough surface having a per cent larger heat transfer coefficient, the total thermal resistance would be reduced only 17 per cent. The figures do not show the e/D associated with each value of A/Ay but these are easily determined from equation (21) of the solution by:   Stanton numbers, mean temperature profiles, and turbulent heat flux profiles are presented for thermal boundary layers which develop over a uniformly rough surface downstream of steps in wall temperature.

Artificially thickened hydrodynamic layers were employed in order to create large unheated starting lengths compared to boundary-layer Cited by: 8.

Turbulent heat transfer from smooth and rough surfaces. International Journal of Heat and Mass Transfer, Vol. 11, Issue. 11, p. Thermal smoothing of rough surfaces in vacuo book between a roughened surface Thermal smoothing of rough surfaces in vacuo book a stream of incompressible fluid flowing over it is dependent on both the viscosity and thermal conductivity of the fluid even when the roughness is large enough for viscosity Cited by: Introduction For increased efficiency in our machines we need a better understand- ing of the mechanism of the contact of rough surfaces, e.g.

its role in the fric- tion and wear of machine parts [1 - 3], thermal and electrical conduction, contact Cited by:   Flat-plate turbulent Thermal smoothing of rough surfaces in vacuo book layer measurements have been made on painted surfaces, smoothed by sanding. The measurements were conducted in a closed return water tunnel, over a momentum thickness Reynolds number Re θ range of to 16, using a two-component laser Doppler velocimeter (LDV).

The mean velocity and Reynolds stress profiles are compared with those for smooth Cited by: Summary. Using Coles additive law of the wall and law of the wake, with constant shift allowed for the effect of roughness, an integral method of analysis is put forward for evaluating the characteristic parameters (friction, wake and roughness parameters) from experimental mean velocity data of rough-wall turbulent boundary layers in zero pressure by: In this paper, for the first time to our knowledge, we experimentally investigate the potential of the DMLS artificial roughness, optimized for convective Thermal smoothing of rough surfaces in vacuo book transfer enhancement, in manufacturing flat and finned heat sinks for electronics by: Scattering from a rough surface in presence of atmospheric turbulence Conference Paper (PDF Available) in Proceedings of SPIE - The International Society for Optical Engineering.

The macroscopic resistance term of equation (1) had been used by Clausing [3] in the study of the thermal resistance between contacting smooth spherical caps in vacuo. He found good agreement between the theory and test data as long as the surfaces were very smooth and applied loads less than a certain by: Fusion bonding of rough surfaces with polishing technique for silicon micromachining Article (PDF Available) in Microsystem Technologies 3(3).

THERMAL SMOOTHING OF ROUGH SURFACES IN VACUO Georg Wahl Translation of "Thermische Glattung von rauhen Oberflachen im Vakuum), Forschung im Ingenieurwesen, Vol.

37, No. 4,pp. (MSA-TM) THEBHAI SMOOTHING OP ROUGH NS SDBFfiCES IN VACDO (National flerojiautics and Space Admiuistratioii) 14 p •CSCL.H.F.

Fig 6: Variations of Nu and Ra Number for smooth and rough surfaces In case of smooth and rough surfaces the Ra value lies between x ≤ Ra ≤ x for all inclinations when power inputW. In case of smooth - and rough surfaces the Ra value lies between x ≤ Ra x for all inclinations when power input : S.

Thombre. Tien, C. L.,“A Correlation for Thermal Contact Conductance of Nominally-Flat Surface in a Vacuum,” Proceedings of the 7th Thermal Conductivity Conference, U.S. Cited by: A chemical etching method is investigated as a possible approach to smoothing metal surfaces automatically. In a chemical etching process metal is removed due to chemical reaction and the dissolved species are transported away from the surface mainly by by: The surface roughness has a large influence on many physical phenomena such as friction, wear, sealing, adhesion, and electrical as well as thermal contacts.

Initially, if two bodies with rough surfaces are pressed together, the “real” contact Cited by: 5. Empirical correlations for microhardness, and the equivalent (sum) rough surface approximation, are discussed.

Suggested correlations for estimating the mean absolute surface slope are summarized and compared with experimental data. The most common assumptions of existing thermal analyses are by: However, the methods presented in [1, 14] for generating rough surfaces expect that 2D surfaces will be created from 2D arrays.

Therefore, it is helpful to have a convenient way to transform a 1D Author: Mary Kathryn Thompson. Impact of Humidity on Adhesion between Rough Surfaces gain by making surfaces as smooth and microstructures as small as possible, these factors also exacerbate unde-sirable adhesion events.

More generally, these systems Impact of Humidity on Adhesion Langmuir, Vol. 16, No. 23, Analysis and Prediction of Constriction Resistance for Contact Between Rough Engineering Surfaces.

Study of thermal contact resistance of rough surfaces based on the practical topography. Computers & Fluids, Vol. Thermal modeling of wafer-based precision glass molding by: American Institute of Aeronautics and Astronautics Sunrise Valley Drive, Suite Reston, VA Contents VIII FoulingTendencies 32 Typesand Phases ofFluids 32 Maintenance,Inspection, Cleaning,Repair,and ExtensionAspects 32 OverallEconomy 32 Fabrication Techniques 33 ChoiceofUnitTypefor IntendedApplications 33 RequirementsofHeatExchangers 34 References 34 SuggestedReadings 35 Bibliography 35.

Emissivity of rough surfaces. I'm thinking of an experiment with a thermal camera. Place two samples at the same temperature and the same emissivity.

Temperature Dependence of Boundary Conditions in Phonon Hydrodynamics of Smooth and Rough Nanowires Article (PDF Available) in Journal of Applied Physics (11) - July   3.

Firebrick have a rough texture, almost as rough as cinderblock. Would there be a difference due to the difference between the surfaces of black firebrick or black glazed tile. (Firebricks have more thermal mass, so after being opened for a peak, the oven will regain its temperature more quickly with firebrick than with tile.

On the Modeling of Elastic Contact between Rough Surfaces NOMENCLATURE A =Area of contact between local asperities An =Nominal contact area Ar =Real contact area between rough surfaces a =Nondimensional distance between the mean asperity height B =Ratio of surface amplitude to wavelength, 1/λ C =Critical yield stress coefficient D =Fractal dimension d.

The transmittance, reflectance, and absorbance of light normally incident on a rough glass surface. The transmittance, reflectance, and absorbance of nm light at angles of incidence up to 85° off normal.

Concluding Thoughts on Calculating the Optical Properties of Rough Surfaces. Combining approaches used across the globe, Electrical Contacts: Fundamentals, Applications, and Technology integrates advances in research and development in the tribological, material, and analytical aspects of electrical contacts with new data on electrical current transfer at the micro- and nanoscales.

The apparent contact angle of a drop on a rough surface is often modeled using either Wenzel's or Cassie's formulas. Previous experiments are not conclusive regarding which formula to use and when.

This information is critical in designing a superhydrophobic substrate for applications in microscale devices. A drop on a rough substrate can occupy multiple equilibrium by:   This is not my area of expertise, but I'll comment a bit.

The roughness of a surface directly affects the efficiency of heat transfer via conduction. Convection, at that point, is merely an afterthought of the initial conduction, assuming there. In a technical sense heat is not reflected.

The thermodynamic definition of heat is the transfer of energy between between two systems or objects as a result of a temperature difference.

However, you may be thinking of all radiation as heat, and t. INTRODUCTION TO PHYSICS OF CONTACT RESISTANCE Contact Between Surfaces Covered with Film • Films covering surfaces need to be electrically or mechanically fractured before metal-to-metal contact is formed • Probe wiping action • Rough surface helps breaking oxide film • Extremely smooth probe tip can produce high contact resistance.

Thermal contact resistance (TCR) theoretical models have been developed for two limiting cases, i) flat rough, and ii) spherical smooth contacts, which are only, simplified cases of real contacts.

However, engineering (real) surfaces have both out-of-flatness and roughness simultaneously. None of the existing theoretical models were developed and. Convection From a Rectangular Plate Abstract Introduction Convective Heat Transfer Types of Convection ASHRAE Fundamentals Thermal Emissivity Still Air ASHRAE Fundamentals Physical Parameters Thermodynamic and Transport Properties of Air Forced convection is greater for rough surfaces than for smooth ones.

All bonds are dependent on the surface area contacted by the adhesive. Because the adhesive on the tape is constrained by the backing, the smoother the surface the more more adhesive is contacted, the better the bond. Rough surfaces have more surf.

It should be able to measure surfaces ranging from extremely smooth to very rough, including the grooves scored into the surface during the mechanical activation process.

ZYGO's 3D optical surface profilers are perfect for this task, as they can measure a wide range of surface textures and reflectivities quickly and precisely. The real fun comes in making real, pdf changes to the topography of your FarmingSimulator map.

Don’t pdf that hill? Flatten it out! GIANTS Editor provides some very powerful terrain-editing tools that make all of this possible. Use the Replace brush The Brush section also gives you the ability to change the key mappings for [ ].Reflection off of smooth surfaces such as download pdf or a calm body of water leads to a type of reflection known as specular reflection.

Reflection off of rough surfaces such as clothing, paper, and the asphalt roadway leads to a type of reflection known as diffuse reflection.

Whether the surface is microscopically rough or smooth has a tremendous impact upon the subsequent .Best product on the market for smoothing rough ebook. I usually use a putty knife to apply it to rough areas and then use a folded wet paper towel to smooth the surface.

Dries quickly, sands easily. Goes on pink so you can see where you applied it .