A type system for components

In modern distributed systems, dynamic reconfiguration, i.e., changing at runtime the communication pattern of a program, is chal- lenging. Generally, it is difficult to guarantee that such modifications will not disrupt ongoing computations. In a previous paper, a solution to this problem was proposed by extending the object-oriented language ABS with a component model allowing the programmer to: i) perform up- dates on objects by means of communication ports and their rebinding; and ii) precisely specify when such updates can safely occur in an object by means of critical sections. However, improper rebind operations could still occur and lead to runtime errors. The present paper introduces a type system for this component model that extends the ABS type system with the notion of ports and a precise analysis that statically enforces that no object will attempt illegal rebinding

Magnetic helicity transported by flux emergence and shuffling motions in Solar Active Region NOAA 10930

We present a new methodology which can determine magnetic helicity transport by the passage of helical magnetic field lines from sub-photosphere and the shuffling motions of foot-points of preexisting coronal field lines separately. It is well known that only the velocity component which is perpendicular to the magnetic field ($\upsilon_{\perp B}$) has contribution to the helicity accumulation. Here, we demonstrate that $\upsilon_{\perp B}$ can be deduced from horizontal motion and vector magnetograms, under a simple relation of $\upsilon_t = \mu_t + \frac{\upsilon_n}{B_n} B_t$ as suggested by D$\acute{e}$moulin & Berger (2003). Then after dividing $\upsilon_{\perp B}$ into two components, as one is tangential and the other is normal to the solar surface, we can determine both terms of helicity transport. Active region (AR) NOAA 10930 is analyzed as an example during its solar disk center passage by using data obtained by the Spectro-Polarimeter and the Narrowband Filter Imager of Solar Optical Telescope on board Hinode. We find that in our calculation, the helicity injection by flux emergence and shuffling motions have the same sign. During the period we studied, the main contribution of helicity accumulation comes from the flux emergence effect, while the dynamic transient evolution comes from the shuffling motions effect. Our observational results further indicate that for this AR, the apparent rotational motion in the following sunspot is the real shuffling motions on solar surface

Fatigue crack layer propagation in silicon-iron

Fatigue crack propagation in metal is almost always accompanied by plastic deformation unless conditions strongly favor brittle fracture. The analysis of the plastic zone is crucial to the understanding of crack propagation behavior as it governs the crack growth kinetics. This research was undertaken to study the fatigue crack propagation in a silicon iron alloy. Kinetic and plasticity aspects of fatigue crack propagation in the alloy were obtained, including the characterization of damage evolution

Three-Dimensionally Confined Optical Modes in Quantum Well Microtube Ring Resonators

We report on microtube ring resonators with quantum wells embedded as an optically active material. Optical modes are observed over a broad energy range. Their properties strongly depend on the exact geometry of the microtube along its axis. In particular we observe (i) preferential emission of light on the inside edge of the microtube and (ii) confinement of light also in direction of the tube axis by an axially varying geometry which is explained in an expanded waveguide model.Comment: 5 pages, 4 figure