摘要 :
This patent application covers a gage for measuring the angularity of the centerline of straight and/or tapered holes with respect to a flat surface. A tapered pin is inserted into the tapered hole and the gage is placed over the ...
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This patent application covers a gage for measuring the angularity of the centerline of straight and/or tapered holes with respect to a flat surface. A tapered pin is inserted into the tapered hole and the gage is placed over the pin and pushed against the surface of the material with the hole in it. A dial indicator provides a direct reading of the angle that the centerline of the hole varies from being perpendicular to the surface. For straight holes, an expanding collet is first inserted into the hole and then the tapered pin is inserted into the collect causing the collet to expand against the sides of the hole and provide an accurate reading on the indicator. (Author)
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The heat transfer processes associated with melting and refreezing a drill hole 500 m in depth and 0.150 m in initial radius through an ice shelf were approximately analyzed. The results were expressed in graphical form showing th...
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The heat transfer processes associated with melting and refreezing a drill hole 500 m in depth and 0.150 m in initial radius through an ice shelf were approximately analyzed. The results were expressed in graphical form showing the time available for experimentation under the hole as a function of heating duration and heating strength. It was found that the refreezing of the drill hole had a much slower rate than the melting of the hole. (Author)
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Solar coronal holes (CHs) are large regions of the corona magnetically open to interplanetary space. The nearly rigid north-south CH boundaries (CHBs) of equatorward extensions of polar CHs are maintained while the underlying phot...
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Solar coronal holes (CHs) are large regions of the corona magnetically open to interplanetary space. The nearly rigid north-south CH boundaries (CHBs) of equatorward extensions of polar CHs are maintained while the underlying photospheric fields rotate differentially, so interchange magnetic reconnection is presumed to be occurring continually at the CHBs. The time and size scales of the required reconnection events at CHBs have not been established from previous observations with soft X-ray images. We use TRACE 195 angstroms observations on 9 December 2000 of a long-lived equatorial extension of the negative-polarity north polar CH to look for changes of > appoximately 5 arcsec to > 20 arcsec at the western CHB. Brightenings and dimmings are observed on both short (approx. 5 minutes) and long (approx. 7 hours) time scales, but the CHB maintains its quasi-rigid location. The transient CHB changes do not appear associated with either magnetic field enhancements or the changes in those field enhancements observed in magnetograms from the Michelson Doppler Imager (MDI) on SOHO. In seven hours of TRACE observations we find no examples of the energetic jets similar to those observed to occur in magnetic reconnection in polar plumes. The lack of dramatic changes in the diffuse CHB implies that gradual magnetic reconnection occurs high in the corona with large (> approximately 10 deg) loops and/or weak coronal fields. We compare our results with recent observations of active regions at CHBs. We also discuss how the magnetic polarity symmetry surrounding quasi-rigid CHs implies an asymmetry in the interchange reconnection process and a possible asymmetry in the solar wind composition from the eastern and western CHB source regions.
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This report describes the development of the EIFS (Equivalent Initial Flaw Size) concept as a potential design tool and the generation of EIFS data as a function of several manufacturing and design variables. Several factors or me...
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This report describes the development of the EIFS (Equivalent Initial Flaw Size) concept as a potential design tool and the generation of EIFS data as a function of several manufacturing and design variables. Several factors or mechanisms that strongly affected the fatigue behavior of fastener holes have been identified and corrected to achieve a 100% improvement in fatigue life. some of these improvements are being implemented in the F-16 production program and the improved drilling will be implemented in the C5A-H Mod. Program.
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The study investigated the effects of oversized bolt holes on the properties ofbolted connections with steel side members. The intent of the study was to determine (1) how well the European Yield Model (EYM) predicts experimental ...
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The study investigated the effects of oversized bolt holes on the properties ofbolted connections with steel side members. The intent of the study was to determine (1) how well the European Yield Model (EYM) predicts experimental results for connections with oversized bolt holes and (2) how the load-deformation behavior of connections is affected by oversized and/or misdrilled holes. Variables included bolt hole size, angle of hole relative to member service, and orientation of load relative to wood grain. The study revealed that the EYM predicts connection yield load for connections with oversized bolt holes with acceptable accuracy. Results indicated little difference in yield load or maximum load with increased bolt hole size. Results indicated a reduction in load of up to 21 percent with increased bolt hole size and an additional reduction of up to 63 percent when holes were drilled at a 2 degree angle from perpendicular to the member surface.
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Navy Underwater Construction Teams require a capability for making access holes through arctic sea ice. Required hole diameters range from less than 4 in. (100 mm) to more than 10 ft (3 m) in ice up to 15 ft (4.6 m) thick. Small d...
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Navy Underwater Construction Teams require a capability for making access holes through arctic sea ice. Required hole diameters range from less than 4 in. (100 mm) to more than 10 ft (3 m) in ice up to 15 ft (4.6 m) thick. Small diameter holes are to be completed in less than 4 hr and large diameter holes in less than 8 hr. The report first gives brief descriptions of the working environment, site access considerations, and probable operational procedure. Principles and techniques for penetrating sea ice are summarized, with an initial list of 14 topics. Twelve of these items are identified as potentially relevant, and are discussed more fully. They include: 1) projectile penetration, 2) shaped charge penetration, 3) high pressure water jets, 4) blasting, 5) flame jets, 6) electrothermal devices, 7) hydrothermal devices, 8) rotary drilling, 9) percussive and vibratory penetration, 10) mechanical cutting, 11) chemical penetration, 12) exotic concepts. The final selection, which takes into account practical concerns and field experience, recommends the following things as basic tools: a) small diameter auger drills (less than 4 in. diam), b) large diameter auger drills (approx. = 9 in. diam), c) chain saws, d) a hot water system for drilling and cutting. The discussion of associated equipment covers electric generators, hoists and lifting tackle, hand tools, and blasting supplies. Considerations is also given to single-fuel operation, bulk melting, and possibilities for use of compressed air.
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Reconstruction of atomically flat and negatively charged Au(111) surfaces duringATM imaging in air is reported. Formation of corrugation line pairs of 0.2 angstroms height and 63 angstroms periodic spacing during scanning is attri...
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Reconstruction of atomically flat and negatively charged Au(111) surfaces duringATM imaging in air is reported. Formation of corrugation line pairs of 0.2 angstroms height and 63 angstroms periodic spacing during scanning is attributed to a local electric field induced transition of the surface layer into the reconstructed phase. The concurrent formation of holes and translation of steps during reconstruction suggests that Au(111) allows for both in-plane contraction and in-plane expansion of interatomic bond distances. STM images reveal that the observed corrugated lines in the structure are mobile and anneal into a stable surface structure on the time-scale of tens of seconds.
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