The Surveyor 3 and Surveyor 4 flight paths and their determination from tracking data

Surveyor 3 and 4 spacecraft flight path

Particulate and aerosol detector

A device is described for counting aerosols and sorting them according to either size, mass or energy. The component parts are an accelerator, a capacitor sensor and a readout. The accelerator is a means for accelerating the aerosols toward the face of the capacitor sensor with such force that they partially penetrate the capacitor sensor, momentarily discharging it. The readout device is a means for counting the number of discharges of the capacitor sensor and measuring the amplitudes of these different discharges. The aerosols are accelerated by the accelerator in the direction of the metal layer with such force that they penetrate the metal and damage the oxide layers, thereby allowing the electrical charge on the capacitor to discharge through the damaged region. Each incident aerosol initiates a discharge path through the capacitor in such a fashion as to vaporize the conducting path. Once the discharge action is complete, the low resistance path no longer exists between the two capacitor plates and the capacitor is again able to accept a charge. The active area of the capacitor is reduced in size by the damaged area each time a discharge occurs

Viking navigation

A comprehensive description of the navigation of the Viking spacecraft throughout their flight from Earth launch to Mars landing is given. The flight path design, actual inflight control, and postflight reconstruction are discussed in detail. The preflight analyses upon which the operational strategies and performance predictions were based are discussed. The inflight results are then discussed and compared with the preflight predictions and, finally, the results of any postflight analyses are presented

Validation of a new method for building a three-dimensional physical model of the skull and dentition

We present a new method for replicating the skull and occlusal surface with an accurate physical model that could be used for planning orthognathic surgery. The investigation was made on 6 human skulls, and a polyvinyl splint was fabricated on the dental cast of the maxillary dentition in each case. A cone beam computed tomogram (CBCT) was taken of each skull and a three-dimensional replica produced. The distorted dentition (as a result of magnification errors and streak artefacts) was removed from the three-dimensional model and replaced by new plaster dentition that was fabricated using the polyvinyl splint and a transfer jig replication technique. To verify the accuracy of the method the human skulls and the three dimensional replica model, with the new plaster dentition in situ, were scanned using a laser scanner. The three-dimensional images produced were superimposed to identify the errors associated with the replacement of the distorted occlusal surface with the new plaster dentition. The overall mean error was 0.72 and SD was (0.26) mm. The accuracy of the method encouraged us to use it clinically in a case of pronounced facial asymmetry

Plasticity Considerations in Probabilistic Ceramic-to-Metal Joint Design

Introduction Ceramic materials are being developed for use in advanced heat engine applications. A key issue in their design and manufacture is joining the ceramic rotor to a metal shaft to transmit power. Design concepts for ceramic-to-metal joints were described in an earlier paper . The goals of this work were to develop new methods for the design and analysis of ceramic-to-metal joints, to predict performance of the joint, and to construct and test ceramic-tometal joints that could support a 20.9 N-m (50 MPa) torque load at 650°C and 950°C with a braze area of 2.0 cm 2 . Some expectation of the strength of the ceramic joint was necessary so that different joint geometries and materials could be explored without the difficulty of making each different design. The difficulty with realizing a predictive design tool for these joints was the probabilistic nature of the ceramic material properties, and the interaction between the metal, ceramic, and braze materials. The heat engine applications of the joints considered here are primarily loaded with high-temperature torsional stresses. Therefore, the test joints were evaluated in torsion, torsional fatigue, and thermal fatigue tests. At the completion of the work, it was desired to not only have a prototype joint design manufactured, but also to confirm the analytical models derived for joint design by comparison with life-tests of the final joint prototypes

Observation of Electroweak Production of a Same-Sign W Boson Pair in Association with Two Jets in pp Collisions root s=13 TeV with the ATLAS Detector

This Letter presents the observation and measurement of electroweak production of a same-sign W boson pair in association with two jets using 36.1     fb − 1 of proton-proton collision data recorded at a center-of-mass energy of √ s = 13     TeV by the ATLAS detector at the Large Hadron Collider. The analysis is performed in the detector fiducial phase-space region, defined by the presence of two same-sign leptons, electron or muon, and at least two jets with a large invariant mass and rapidity difference. A total of 122 candidate events are observed for a background expectation of 69 ± 7 events, corresponding to an observed signal significance of 6.5 standard deviations. The measured fiducial signal cross section is σ fid = 2.89 + 0.51 − 0.48 ( stat ) + 0.29 − 0.28 ( syst )     fb

Reading terminal market : an illustrated history

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Trichoptera Of The Cahaba River System In Alabama

Volume: 95Start Page: 103End Page: 11