Optical properties of evaporated Ge20Se80−x Tl x thin films

Chalcogenide glasses with composition Ge₂₀Se_80–x Tl _x (x=10, 15, 20, 25, 35%) have been prepared by the usual melt-quenching technique. Thin films of the mentioned compositions have been prepared by the electron beam evaporation. In addition, another set taken from the composition ofX=30 at % with different thicknesses (d=14.7, 30.0, 56.5, 70.0, 101.0, 180.0 nm) have been taken into consideration. The X-ray diffraction (XRD) analysis revealed the amorphous nature of the prepared films. It was found that, in contrast to the optical gap (E _op), both the extent of the band tailing (B), and the band gap (E _e) increase with increasing thallium content. In other side,E _op showed thickness independency. The refractive index (n) showed obvious dependence on both composition and thickness also on the energy of the incident radiation.     

Deriving real-time action systems in a sampling logic

Action systems have been shown to be applicable for modelling and constructing systems in both discrete and hybrid domains. We present a novel semantics for action systems using a sampling logic that facilitates reasoning about the truly concurrent behaviour between an action system and its environment. By reasoning over the apparent states, the sampling logic allows one to determine whether a state predicate is definitely or possibly true over an interval. We present a semantics for action systems that allows the time taken to sample inputs and evaluate expressions (and hence guards) into account. We develop a temporal logic based on the sampling logic that facilitates formalisation of safety, progress, timing and transient properties. Then, we incorporate this logic to the method of enforced properties, which facilitates stepwise refinement of action systems.     

Tracking dynamics of glass formers and modifiers via correlation maps of molecular dynamics simulation

In this study, we describe a method to construct a correlation map that captures the evolution of species-specific dynamic information through the spatial correlation of high-dimensional time-series molecular dynamics (MD) simulation dataset for a series of borosilicate glasses. The correlation is based on ‘displacement’ between a pair of atomic configurations determined by the root mean square distance (RMSD) metric. We implement the correlation map as a quantitative visualization tool that provides a compressed representation of a high-dimensional molecular dynamics dataset to inspect various physical aspects and capture distinct atomic dynamics—from large fluctuations to small local oscillations—for high-temperature melt, linear cooling, and low-temperature equilibration processes during molecular dynamics simulation of glasses. We capture species-specific dynamics using this method that show different cooling dynamics for different glass formers and modifiers, especially the onset of slow dynamics and the variation of atomic dynamics at high temperatures. Furthermore, we show that the species-specific atomic dynamics have structural origins that depend on the composition of the simulated borosilicate glasses. The correlation map serves as a visualization tool to rapidly survey changes in atomic configurations during different simulation conditions.     

Mechanized proofs of opacity: a comparison of two techniques

Software transactional memory (STM) provides programmers with a high-level programming abstraction for synchronization of parallel processes, allowing blocks of codes that execute in an interleaved manner to be treated as atomic blocks. This atomicity property is captured by a correctness criterion called opacity, which relates the behaviour of an STM implementation to those of a sequential atomic specification. In this paper, we prove opacity of a recently proposed STM implementation: the Transactional Mutex Lock (TML) by Dalessandro et al. For this, we employ two different methods: the first method directly shows all histories of TML to be opaque (proof by induction), using a linearizability proof of TML as an assistance; the second method shows TML to be a refinement of an existing intermediate specification called TMS2 which is known to be opaque (proof by simulation). Both proofs are carried out within interactive provers, the first with KIV and the second with both Isabelle and KIV. This allows to compare not only the proof techniques in principle, but also their complexity in mechanization. It turns out that the second method, already leveraging an existing proof of opacity of TMS2, allows the proof to be decomposed into two independent proofs in the way that the linearizability proof does not.     

Integrating Owicki–Gries for C11-Style Memory Models into Isabelle/HOL

Journal of Automated Reasoning - Weak memory presents a new challenge for program verification and has resulted in the development of a variety of specialised logics. For C11-style memory models,...     

An Overview to the Concept of Smart Coupling and Battery Management for Grid Connected Photovoltaic Battery System

The paper gives an overview on the need for smart coupling for battery management in grid integrated renewable energy system (RES). Grid integrated photovoltaic (PV) battery system, as being popular and extensively used has been discussed in the paper. Smart coupling refers to intelligent grid integration such that it can foresee local network conditions and issue battery power flow management strategy accordingly to shave the peak PV and peak load. Therefore, a need for predictive energy management arises for smart integration to the grid and supervision of the power flow in accordance to the grid conditions. This is also a running project at the Institute of Energy Systems (INES), Offenburg University of Applied Science, Germany since January, 2015. The paper should provide insights to the motivation, need and gives an outlook to the features of desired predictive energy management system (PEMS).     

Phase separation and crystallization of La_2O_3 doped ZnO-B_2O_3-SiO_2 glass

In order to investigate the effect of the La_2O_3 on the phase separation and crystallization of ZnO-B_2O_3-SiO_2 glass, after the occurence of the phase separation and crystallization of glasses by heat treatment, the microstructure morphology and distribution of elements in different sample areas were characterized by the scanning electron microscopy(SEM) and energy dispersive spectroscopy(EDS); the non-isothermal crystallization kinetics of the glass samples was studied by using a differential scanning calorimeter(DSC) and the precipitated crystals of crystallized glass were determined by the X-ray diffraction(XRD). The results suggest that the phase separation and crystallization of 60ZnO-30 B_2O_3-10SiO_2 glass occur at glass surface, and the incorporation of small amount(4 mol%) of La_2O_3 significantly inhibits the glass phase separation and consequently improves the thermal stability of glass.Doping of La_2O_3 accelerates the glass crystallization at the elevated temperature(660 ℃), making the depth of crystal layer thicker and diffraction intensity in XRD patterns stronger. However, due to the precipitation of several crystals that occur simultaneously when La_2O_3 doping amount is 4 mol%, crystallization of the 60ZnO-30B_2O_3-10SiO_2 glass is obviously depressed, the crystallization activation energy Ec and the relative crystallinity X_c of the glass reach the maximum and the minimum values, respectively.Although transition from one-dimensional growth of crystals to two-dimensional growth of crystals results from La_2O_3 addition, the one-dimensional growth of crystals remains dominant in crystallization process. This work can provide some useful information for preparing glass ceramics with nano-crystals precipitated in the glass surface.