Topological dynamical systems of type I

AbstractThe equivalence of existence of a Borel section to nonexistence of recurrent aperiodic points for homeomorphisms of locally compact topological spaces is proved using the theory of C*-algebras

A Schmidt number for density matrices

We introduce the notion of a Schmidt number of a bipartite density matrix, characterizing the minimum Schmidt rank of the pure states that are needed to construct the density matrix. We prove that Schmidt number is nonincreasing under local quantum operations and classical communication. We show that $k$-positive maps witness Schmidt number, in the same way that positive maps witness entanglement. We show that the family of states which is made from mixing the completely mixed state and a maximally entangled state have increasing Schmidt number depending on the amount of maximally entangled state that is mixed in. We show that Schmidt number {\it does not necessarily increase} when taking tensor copies of a density matrix $\rho$; we give an example of a density matrix for which the Schmidt numbers of $\rho$ and $\rho \otimes \rho$ are both 2.Comment: 5 pages RevTex, 1 typo in Proof Lemma 1 correcte

Design, modelling, simulation and integration of cyber physical systems: Methods and applications

The main drivers for the development and evolution of Cyber Physical Systems (CPS) are the reduction of development costs and time along with the enhancement of the designed products. The aim of this survey paper is to provide an overview of different types of system and the associated transition process from mechatronics to CPS and cloud-based (IoT) systems. It will further consider the requirement that methodologies for CPS-design should be part of a multi-disciplinary development process within which designers should focus not only on the separate physical and computational components, but also on their integration and interaction. Challenges related to CPS-design are therefore considered in the paper from the perspectives of the physical processes, computation and integration respectively. Illustrative case studies are selected from different system levels starting with the description of the overlaying concept of Cyber Physical Production Systems (CPPSs). The analysis and evaluation of the specific properties of a sub-system using a condition monitoring system, important for the maintenance purposes, is then given for a wind turbine

Maintenance Task Classification: Towards Automated Robotic Maintenance for Industry

AbstractThe business model of high-value capital assets is shifting from purchasing a physical product to acquiring a result or a function supported by the product combined with a number of related services. One such service, maintenance, is perhaps the most efficient way to keep the function available during the product lifecycle. Automation has played a vital role in industry throughout history, particularly within the production line. With the movement towards providing product service systems the need for services such as maintenance are increasingly important for a manufactured product, and the pull towards automation may drive down costs and improve performance time. Although currently robotic applications to maintenance beyond monitoring and inspection tasks are not common, this research aims at exploring the feasibility of future maintenance robots that can perform a variety of maintenance tasks. As its first step, this work looks first at investigation, cataloging and classification of a number of maintenance tasks using standard industrial engineering techniques such as time motion, method or workflow analysis. This involves decomposing the maintenance work into a number of ‘unit tasks’ required to be performed in order to accomplish the specified maintenance

Site-selective silicon adatom desorption using femtosecond laser pulse pairs and scanning tunneling microscopy

We performed an experimental study of silicon adatom desorption from the Si~111!-737 surfaceusing femtosecond laser pulse pair excitation with 80 fs pulse duration, 800 nm center wavelength,300 mW average power, and a 100 MHz repetition rate. Using scanning tunneling microscopy, wedirectly recorded the desorption characteristics at each delay setting for each of the four adatombinding sites. The study revealed a preferential dependence between the delay time and the adatomsites within a 66.6–1000 fs delay range

Multi Domain Design: Integration and Reuse

Design of mechatronic systems is becoming increasingly complex. Companies must continuously reduce time-to-market while increasing the quality, diversity, and functionality of their products. As a result, more and more specialists from various domains are needed to develop such products. To reduce time-to-market, many companies look to reducing the time it takes to design a product. Many focus on the reuse of design objects, leading to libraries of templates and standard components to speed up their design process. However, these reusable design objects are developed and maintained in the specialists’ domains, resulting in communication and integration issues between these domains. This paper discusses these issues and proposes a combined approach for model reuse, design integration, and communication between the designers, design tools, and models involved. A case study at a multi-national company successfully demonstrated that the approach leads to a faster and more consistent design process

Experiments performed with bubbly flow in vertical pipes at different flow conditions covering the transition region: Simulation by coupling Eulerian, Lagrangian and 3D random walks models

[EN] Two phase flow experiments with different superficial velocities of gas and water were performed in a vertical upward isothermal cocurrent air-water flow column with conditions ranging from bubbly flow, with very low void fraction, to transition flow with some cap and slug bubbles and void fractions around 25%. The superficial velocities of the liquid and the gas phases were varied from 0.5 to 3 m/s and from 0 to 0.6 m/s, respectively. Also to check the effect of changing the surface tension on the previous experiments small amounts of 1-butanol were added to the water. These amounts range from 9 to 75 ppm and change the surface tension. This study is interesting because in real cases the surface tension of the water diminishes with temperature, and with this kind of experiments we can study indirectly the effect of changing the temperature on the void fraction distribution. The following axial and radial distributions were measured in all these experiments: void fraction, interfacial area concentration, interfacial velocity, Sauter mean diameter and turbulence intensity. The range of values of the gas superficial velocities in these experiments covered the range from bubbly flow to the transition to cap/slug flow. Also with transition flow conditions we distinguish two groups of bubbles in the experiments, the small spherical bubbles and the cap/slug bubbles. Special interest was devoted to the transition region from bubbly to cap/slug flow; the goal was to understand the physical phenomena that take place during this transition A set of numerical simulations of some of these experiments for bubbly flow conditions has been performed by coupling a Lagrangian code, that tracks the three dimensional motion of the individual bubbles in cylindrical coordinates inside the field of the carrier liquid, to an Eulerian model that computes the magnitudes of continuous phase and to a 3D random walk model that takes on account the fluctuation in the velocity field of the carrier fluid that are seen by the bubbles due to turbulence fluctuations. Also we have included in the model the deformation that suffers the bubble when it touches the wall and it is compressed by the forces that pushes it toward the wall, provoking that the bubble rebound like a ball.The authors of this paper are indebted to the National Plan of I+D by the support of the coordinated projects REMOD-ERN ENE2010-21368-C02-01/CON and ENE2010-21368-C02-02/CON to perform the experiments.Muñoz-Cobo, JL.; Chiva, S.; Ali Abdelaziz Essa, M.; Mendez, S. (2012). Experiments performed with bubbly flow in vertical pipes at different flow conditions covering the transition region: Simulation by coupling Eulerian, Lagrangian and 3D random walks models. Archives of Thermodynamics. 33(1):3-39. https://doi.org/10.2478/v10173-012-0001-4S33933