Studies of noise transmission in advanced composite material structures

Noise characteristics of advanced composite material fuselages were discussed from the standpoints of applicable research programs and noise transmission theory. Experimental verification of the theory was also included

Visualisation and evaluation of electrical contact spots and asperities of a given contact system using x-ray computed tomography

The electrical contact is identified as the most common factor as to why electrical and electronic devices fail. The electrical contacts fail due to a variation of factors such as the normal-force (force perpendicular to the surface) and the general contact design, the wear and the environmental and electrical parameters. This research attempts to address these factors by introducing an innovative inspection method to investigate a contact system connection without the need to prior dismantle it. The X-ray Computed Tomography (CT) is used and several Contact Analysis Techniques (CAT*) are developed and implemented with a suite of tools in MATLAB in order to accurately analyse the acquired images from the X-ray CT. The CAT* produce visualisation of the contact interface (contact spots) between the conductors of the contact system as well as the visualisation of their contact asperities (structures above and below the contact spots). Furthermore, the CAT* produce visualisation of any cross-section slice of the contact system and show from which voxels the electric current flows through. These visualisations can be analysed to evaluate the degradation process of contact spots and contact asperities under different current loading tests. An in depth appraisal of X-ray CT as a non-destructive visualisation technique for investigating electrical contacts is performed and procedures enhancing the deliverables of the technique are introduced. The outcomes of this research confirm that the use of X-ray CT visualisation technique in the field of electrical contacts can improve our understanding in the field. Moreover, the CAT* could help the manufacture companies of contact systems to develop more reliable contact systems examining their features for different contact materials under different applied forces and different environmental and electrical parameters

Optimizing mining rates under financial uncertainty in global mining complexes

AbstractThis paper presents a distributed and dynamic programming framework to the mining production rate target tracking of multiple metal mines under financial uncertainty. A single mine׳s target tracking is stated as a stochastic optimization problem and the solution is obtained by solving the dynamic program which gives the optimal production rate schedule of each mine as a Markovian feedback control on the price process. The global solution is distributed on multiple mines by a policy iteration method, and this iterative method is shown to provide the unique equilibrium among Markovian strategies. Numerical results confirm the efficacy of the proposed global method when compared to individual optimization of mining rate target tracking

Discovery of a transient radiation belt at Saturn

Radiation belts have been detected in situ at five planets. Only at Earth however has any variability in their intensity been heretofore observed, in indirect response to solar eruptions and high altitude nuclear explosions. The Cassini spacecraft's MIMI/LEMMS instrument has now detected systematic radiation belt variability elsewhere. We report three sudden increases in energetic ion intensity around Saturn, in the vicinity of the moons Dione and Tethys, each lasting for several weeks, in response to interplanetary events caused by solar eruptions. However, the intensifications, which could create temporary satellite atmospheres at the aforementioned moons, were sharply restricted outside the orbit of Tethys. Unlike Earth, Saturn has almost unchanging inner ion radiation belts: due to Saturn's near-symmetrical magnetic field, Tethys and Dione inhibit inward radial transport of energetic ions, shielding the planet's main, inner radiation belt from solar wind influences

Prädiktoren für Frühkomplikationen des Schlaganfalles

Die vorliegende Arbeit hat zum Ziel, Prädiktoren für das Auftreten von Frühkomplikationen in der prähospitalen Akutphase des Schlaganfalles auszumachen. Anhand von digitalisierten Notarztprotokollen wurden sieben behandlungspflichtige Frühkomplikationen formuliert, die den Einsatz eines Notarztes erforderlich machen: Die Intubation, bradykarde und tachykarde Herzrhythmusstörungen, der Status epilepticus, die hypertensive Krise, der hypotensiver Schock und das Akute Koronarsyndrom. Nach multivariater Analyse erwiesen sich ein Erkrankungsalter bis einschließlich 74 Jahren, weibliches Geschlecht, ein niedriger GCS-Wert, eine Herzfrequenz unter 60/min., eine als pathologisch eingestufte Atmung und Pupillenreaktion und ein nicht orientierter Bewußtseinszustand als unabhängige Prädiktoren für das Auftreten einer Frühkomplikation. Dies könnte die Grundlage für einen möglichen Score sein, mit dem nichtärztliches Rettungspersonal die Notarztindikation abschätzen könnte

Magnetospheric considerations for solar system ice state

The current lattice configuration of the water ice on the surfaces of the inner satellites of Jupiter and Saturn is likely shaped by many factors. But laboratory experiments have found that energetic proton irradiation can cause a transition in the structure of pure water ice from crystalline to amorphous. It is not known to what extent this process is competitive with other processes in solar system contexts. For example, surface regions that are rich in water ice may be too warm for this effect to be important, even if the energetic proton bombardment rate is very high. In this paper, we make predictions, based on particle flux levels and other considerations, about where in the magnetospheres of Jupiter and Saturn the ∼MeV proton irradiation mechanism should be most relevant. Our results support the conclusions of Hansen and McCord (2004), who related relative level of radiation on the three outer Galilean satellites to the amorphous ice content within the top 1 mm of surface. We argue here that if magnetospheric effects are considered more carefully, the correlation is even more compelling. Crystalline ice is by far the dominant ice state detected on the inner Saturnian satellites and, as we show here, the flux of bombarding energetic protons onto these bodies is much smaller than at the inner Jovian satellites. Therefore, the ice on the Saturnian satellites also corroborates the correlation

A Two-Player Game of Life

We present a new extension of Conway's game of life for two players, which we call p2life. P2life allows one of two types of token, black or white, to inhabit a cell, and adds competitive elements into the birth and survival rules of the original game. We solve the mean-field equation for p2life and determine by simulation that the asymptotic density of p2life approaches 0.0362.Comment: 7 pages, 3 figure

Effect of heliox breathing on flow limitation in chronic heart failure patients

Patients with chronic heart failure (CHF) exhibit orthopnoea and tidal expiratory flow limitation in the supine position. It is not known whether the flow-limiting segment occurs in the peripheral or central part of the tracheobronchial tree. The location of the flow-limiting segment can be inferred from the effects of heliox (80% helium/20% oxygen) administration. If maximal expiratory flow increases with this low-density mixture, the choke point should be located in the central airways, where the wave-speed mechanism dominates. If the choke point were located in the peripheral airways, where maximal flow is limited by a viscous mechanism, heliox should have no effect on flow limitation and dynamic hyperinflation. Tidal expiratory flow limitation, dynamic hyperinflation and breathing pattern were assessed in 14 stable CHF patients during air and heliox breathing at rest in the sitting and supine position. No patient was flow-limited in the sitting position. In the supine posture, eight patients exhibited tidal expiratory flow limitation on air. Heliox had no effect on flow limitation and dynamic hyperinflation and only minor effects on the breathing pattern. The lack of density dependence of maximal expiratory flow implies that, in CHF patients, the choke point is located in the peripheral airways