NASA Communications Division (NASCOM) Tracking and Data Relay Satellite System (TDRSS) shuttle multiplexer-demultiplexer data system (MDM) and supporting items

The multiplexer-demultiplexer (MDM) project included the design, documentation, manufacture, and testing of three MDM Data Systems. The equipment is contained in 59 racks, and includes more than 3,000 circuit boards and 600 microprocessors. Spares, circuit card testers, a master set of programmable integrated circuits, and a program development system were included as deliverables. All three MDM's were installed, and were operationally tested. The systems performed well with no major problems. The progress and problems analysis, addresses schedule conformance, new technology, items awaiting government approval, and project conclusions are summarized. All contract modifications are described

Empirical fragility curves: The effect of uncertainty in ground motion intensity

Empirical fragility curves derived from large post-disaster databases with data aggregated at municipality-level, commonly make the assumption that the ground motion intensity level is known and is determined at the centroid of each municipality from a ground motion prediction equation. A flexible Bayesian framework is applied here to the 1980 Irpinia database to explore whether more complex statistical models that account for sources of uncertainty in the intensity can significantly change the shape of the fragility curves. Through this framework the effect of explicitly modelling the uncertainty in the intensity, the spatial correlation of its intra-event component and the uncertainty due to the scatter of the buildings in the municipality are investigated. The analyses showed that the results did not change substantively with increased model complexity or the choice of prior. Nonetheless, informed decisions should be based on the defensible modelling of the significant variability in the data between municipalities

Structures of masonry walls in buildings of permanent ruin – causes of damage and methods of repairs

Currently there is a lot of castles classified as objects of the permanent ruin. In according to conservation doctrine, it is needed to protect this objects and prevent further degradation. Usually one of the most destructed element in this type of object is masonry wall. In this article has been described selected types of the masonry walls of the permanent ruin, causes of their damages and repairs methods.Currently there is a lot of castles classified as objects of the permanent ruin. In according to conservation doctrine, it is needed to protect this objects and prevent further degradation. Usually one of the most destructed element in this type of object is masonry wall. In this article has been described selected types of the masonry walls of the permanent ruin, causes of their damages and repairs methods

Simulated Annealing Routing and Wavelength Lower Bound Estimation on WDM Optical Multistage Networks

Multistage interconnection networks (MINs) are popular in switching and communication applications and have been used in telecommunication and parallel computing systems for many years. Crosstalk a major problem introduced by an optical MIN, is caused by coupling two signals within a switching element. We focus on an efficient solution to avoiding crosstalk by routing traffic through an N3N optical network to avoid coupling two signals within each switching element using wavelength-division multiplexing (WDM) and a time-division approach. Under the constraint of avoiding crosstalk, the interest is on realizing a permutation that uses the minimum number of passes for routing. This routing problem is an NP-hard problem. Many heuristic algorithms are already designed by researchers to perform this routing such as a sequential algorithm, a degree-descending algorithm, etc. The genetic algorithm is used successfully to improve the performance over the heuristic algorithms. The drawback of the genetic algorithm is its long running times. We use the simulated annealing algorithm to improve the performance of solving the problem and optimizing the result. In addition, a wavelength lower bound estimate on the minimum number of passes required is calculated and compared to the results obtained using heuristic, genetic, and simulated annealing algorithms. Many cases are tested and the results are compared to the results of other algorithms to show the advantages of simulated annealing algorithm

Comparative linear accuracy of cone beam CT derived 3D images in orthodontic analysis.

Objective . To compare the in vitro reliability and accuracy of linear measurements between cephalometric landmarks on CBCT 3D images with varying basis projection images to direct measurements on human skulls. Methods . Sixteen linear dimensions between anatomical sites marked on 19 human skulls were directly measured. Skulls were imaged with CBCT at three settings: 153, 306, and 612 basis projections. The mean absolute error and modality mean of linear measurements between landmarks on 3D images were compared to the anatomic truth. Results . No difference in mean absolute error between the scan settings was found. The average skull absolute error between marked reference points were less than the distances between unmarked reference sites. Conclusion . CBCT measurements were consistent between scan sequences and for direct measurements between marked reference points. Reducing the number of projections for 3D reconstruction did not lead to reduced dimensional accuracy and potentially provides reduced patient radiation exposure

Sustainability in Civil Engineering: Integrated Mix of Some Non-Invasive Sensing Techniques for Conservation and Restoration of Historical Buildings and Frescoes

AbstractSanta Maria of the Palomba Sanctuary was built in XVth century on a pre-existing medieval crypt, situated in a splendid landscape, on the south facing ravine on which stands the city of Matera, integrating in a wonderful way the underground and sub divo building; in the ages shortly following a notable cycle of frescoes was painted renewing the decorative state of the underground church.Over many years, the building fell into decay, the structures and frescoes were flooded and damaged; so that from 1980 important restoration works were carried out, constructing ventilation canals under the floor of the hypogeic church, incorporating heating pipes, connected to solar thermal panels in such a way to secure the optimum thermohygrometric conditions for conservation. After almost thirty years, before working on the restoration of the frescoes it was necessary to completely and objectively characterize the existing physical conditions

Theory of an airfoil equipped with a jet flap under low-speed flight conditions

A theory is developed, for the inviscid, incompressible flow past a thin airfoil equipped with a thin, part-span jet flap, by treating the induced flowfields of the jet and the wing separately and by obtaining the fully coupled solution in an iterative manner. Spanwise variation of the jet vortex strength is assumed to be elliptical in the analysis. Since the method considers the vorticity associated with the jet to be positioned on the computed locus of the jet, the downwash aft of the wing is evaluated as well as forces and moments on the wing. A lifting-surface theory is incorporated for the aerodynamics of the wing. Computational results are presented for a rectangular wing at momentum coefficients above 2.0 and compared with existing linear theories and experimental data. Good agreement is found for small angles of attack, jet-deflection angles, and jet-momentum coefficients where the linear theories and experimental data are applicable. Downwash data at a point in the vicinity of a control surface, the load distribution on the airfoil, and the jet, and the jet location are also presented for representative flight conditons