Papers by Darold Wobschall
PhDT, 1966
Bookmarks Related papers MentionsView impact
Elsevier eBooks, 1960
Four basic types of carbons were prepared, namely from (1) soft filler-soft binder, (2) soft fill... more Four basic types of carbons were prepared, namely from (1) soft filler-soft binder, (2) soft filler-hard binder, (3) hard filler-soft binder and (4) hard filler-hard binder. The room temperature elastic constants and permanent set for these types of carbons were measured as a function of heat-treatment temperature. A sensitive apparatus using linear variable differential transformers was developed for measuring elastic moduli in bending and torsion in which the specimen can be stressed in either of two opposite directions. It was found that the dependence of Young's modulus and rigidity modulus on heat-treatment temperature are similar. Hysteresis loops are observed in both force-deflection and torque-twist measurements; the second and third loops becoming progressively more narrow. Annealing the specimen at 1000°C for a few minutes was found to restore the virgin behavior. Crackling noises are detected when carbon specimens are strained for the first time beyond the limits of previous deflection. Room temperature creep was observed which depends logarithmically on time, showing the absence of viscous creep.
Bookmarks Related papers MentionsView impact
An apparatus has been constructed for measuring the static Young's modulus of carbons in bend... more An apparatus has been constructed for measuring the static Young's modulus of carbons in bending at high temperature. The specimen is heated in a graphite tube furnace and its deflection under load is determined by measuring the deflection at three points with Linear Variable Differential Transformers and appropriate electronic circuits. The force-deflection curves are recorded on an X–Y recorder. Four basic types of carbons were measured, namely, those prepared from (1) soft filler–soft binder, (2) soft filler–hard binder, (3) hard filler–soft binder, and (4) hard filler–hard binder. The usual maximum at about 1800°C was observed for graphitized soft filler bodies; bodies with hard filler showed only a continuous decrease in modulus with increase of temperature. A system of temperature curves was obtained for soft filler–soft binder and for hard filler–hard binder rods as they were heat treated to successively higher temperatures. All the Young's modulus curves show maxima shifting in position with heat treatment except for the graphitized hard filler material.
Bookmarks Related papers MentionsView impact
Bookmarks Related papers MentionsView impact
ABSTRACT
Bookmarks Related papers MentionsView impact
Measurement of Young's modulus was made on a graphite 1/2-in.-diam. rod ; for eight differen... more Measurement of Young's modulus was made on a graphite 1/2-in.-diam. rod ; for eight different directions of bending. Additional attenuation measurements ; were made on carbon rods. An effort was made to determine the cause of variance ; of the thermal conductivity as evidenced upon repeated heating and cooling of the ; carbon test specimens. (W.L.H.);
Bookmarks Related papers MentionsView impact
ABSTRACT
Bookmarks Related papers MentionsView impact
Families of curves of the dependence of Young's modulus on temperature ; and on heat tre... more Families of curves of the dependence of Young's modulus on temperature ; and on heat treatment were obtained for four basic types of carbons, using high ; temperature equipment. The decisive influence of filler type was established. ; As a result of gained experience, improvements in the associated electronics were ; introduced. The amplitude dependence of the internal friction and dynamic ; Young's modulus were, for the first time, investigated at room temperature for ; vibrations in the sonic range of frequencies for several types of carbons. ; Reproducibility was achieved in measurements of thermal conductivity with the new ; high temperature test apparatus and families of curves of the dependence of the ; conductivity on temperature and on heat treatment obtained for soft carbon. A ; new technique of determining the heat conductivity of carbons without internal ; heat generation was tried and found to work up to 1800 deg C. Improved results ; were obtained with the transient state technique of determination of the heat ; diffusivity by using a new fast responding pyrometer and a new improved apparatus ; for the steady sinusoidal wave technique constructed. (auth);
Bookmarks Related papers MentionsView impact
Review of Scientific Instruments, 1961
A transistorized circuit particularly designed as an output indicator for linear variable differe... more A transistorized circuit particularly designed as an output indicator for linear variable differential transformers is given. It is relatively simple to construct, adjust, and operate. The advantages of a phase-sensitive detector for the measurements of small displacements is discussed. Resolution of the unit is about 0.05 μ; the linearity is about ¼%.
Bookmarks Related papers MentionsView impact
Bookmarks Related papers MentionsView impact
Journal of Chemical Physics, Jun 1, 1965
Observations were made of the cyclotron resonance absorption of O—, O2—, H—, OH—, and H2O— in oxy... more Observations were made of the cyclotron resonance absorption of O—, O2—, H—, OH—, and H2O— in oxygen containing water vapor. A technique utilizing a circularly polarized rf electric field is described which allows the cyclotron resonance absorptions of negative and positive ions to be distinguished. The production of O2— was found to depend on the presence of water vapor as well as oxygen and is probably due to charge exchange with H—.
Bookmarks Related papers MentionsView impact
Journal of Periodontal Research, May 1, 1994
Bookmarks Related papers MentionsView impact
Conference record, Sep 1, 2007
Bookmarks Related papers MentionsView impact
Journal of Theoretical Biology, Dec 1, 1968
Bookmarks Related papers MentionsView impact
Proceedings of SPIE, May 28, 1999
Recent developments in CMOS image detectors are changing the way digital imaging is performed for... more Recent developments in CMOS image detectors are changing the way digital imaging is performed for many applications. The replacement of charge coupled devices (CCDs), with CMOS detectors is a desirable paradigm shift that will depend on the ability to match the high performance characteristics of CCDs. Digital X-ray imaging applications (chest X-ray, mammography) would benefit greatly from this shift because CMOS detectors have the following inherent characteristics: (1) Low operating power (5 - 10 times lower than CCD/processing electronics). (2) Standard CMOS manufacturing process (CCD requires special manufacturing). (3) On-chip integration of analog/digital processing functions (difficult with CCD). (4) Low Cost (5 - 10 times lower cost than CCD). The achievement of both low cost and low power is highly desirable for portable applications as well as situations where large, expensive X-ray imaging machines are not feasible (small hospitals and clinics, emergency medical vehicles, remote sites). Achieving this goal using commercially available components would allow rapid development of such digital X-ray systems as compared with the development difficulties incurred through specialized direct detectors and systems. The focus of this paper is to evaluate a CMOS image detector for medical X-ray applications and to demonstrate the results obtained from a prototype CMOS digital X-ray camera. Results from the images collected from this optically-coupled camera are presented for a particular lens, X-ray conversion screen, and demagnification factor. Further, an overview of the overall power consumption and cost of a multi-sensor CMOS mosaic compared to its CCD counterpart are also reported.
Bookmarks Related papers MentionsView impact
Journal of Chemical Physics, Nov 15, 1967
Through determinations of the widths of ion cyclotron resonance lines as a function of pressure a... more Through determinations of the widths of ion cyclotron resonance lines as a function of pressure and electric field strengths, the ion—molecule collision cross sections of H+, H2+, H3+, He+, Ar+, N2+, N+, O2+, O2−, and O− were obtained. Agreement with dc mobility data was found. In particular, the minimum in collision frequency for H3+ in H2 at E/P0=60 V/cm·torr was confirmed. The cross sections for H2+ in H2 are 275 and 68 Å2 at low and high E/P, respectively.
Bookmarks Related papers MentionsView impact
Chemistry and Physics of Lipids, Apr 1, 1974
ABSTRACT
Bookmarks Related papers MentionsView impact
Journal of the American Chemical Society, 1972
Bookmarks Related papers MentionsView impact
Review of Scientific Instruments, Aug 1, 1987
A displacement sensor based on the ratio of fiber-optic light emitted from two fixed position opt... more A displacement sensor based on the ratio of fiber-optic light emitted from two fixed position optical fibers into a third, movable fiber connected to a photodetector is described. Square-wave modulated light of opposite phases produces a corresponding square wave at the detector which has zero ac amplitude at the center position and an amplitude proportional to displacement on either side of the detection fiber. A phase-sensitive detector produces a positive dc output voltage for positive displacements and negative for negative displacements.
Bookmarks Related papers MentionsView impact
Transportation Research Record, 1975
Moisture content is an important parameter that controls the performance of earth materials. Beca... more Moisture content is an important parameter that controls the performance of earth materials. Because satisfactory techniques were not available, this study was undertaken to develop new instrumentation that could be permanently installed in highway substructures for long-term monitoring of moisture content. Moisture content determination requires that the amount of water and the dry weight in a given volume of soil be obtained. This study considered only the amount of water. A concept that involved the relationship between the amount of water in soil and the dielectric constant, an electrical property, was investigated. The electrical capacitance (C) of a pair of electrodes with moist material between them is related to to the dielectric constant (K) by C equals (Alpha times Epsilon) K, where Alpha is a constant based on the geometry of the electrodes and Epsilon is the permittivity of the vacuum. So that instrumentation problems encountered in the measurement of capacitance and dielectric constant with laboratory methods used in the field could be overcome, the sensor electrodes and soil were incorporated in the resonance circuit whose frequency of oscillation is a function of the circuit components. The measured output is the difference between the frequency in soil and in an electonic reference substituted for the soil. The curcuit design was first tested with the electrodes forming a container into which soil could be placed. Several configurations of the embedded sensor were designed and tested. The capacitance concept was useful for sensing change in the amount of moisture per unit volume of soil.
Bookmarks Related papers MentionsView impact
Uploads
Papers by Darold Wobschall