A universe of processes and some of its guises

Our starting point is a particular `canvas' aimed to `draw' theories of physics, which has symmetric monoidal categories as its mathematical backbone. In this paper we consider the conceptual foundations for this canvas, and how these can then be converted into mathematical structure. With very little structural effort (i.e. in very abstract terms) and in a very short time span the categorical quantum mechanics (CQM) research program has reproduced a surprisingly large fragment of quantum theory. It also provides new insights both in quantum foundations and in quantum information, and has even resulted in automated reasoning software called `quantomatic' which exploits the deductive power of CQM. In this paper we complement the available material by not requiring prior knowledge of category theory, and by pointing at connections to previous and current developments in the foundations of physics. This research program is also in close synergy with developments elsewhere, for example in representation theory, quantum algebra, knot theory, topological quantum field theory and several other areas.Comment: Invited chapter in: "Deep Beauty: Understanding the Quantum World through Mathematical Innovation", H. Halvorson, ed., Cambridge University Press, forthcoming. (as usual, many pictures

Damage assessment of concrete structures exposed to fire

During a fire, concrete structures behave in most cases very well. It could therefore be of economic interest to repair the damaged structures, as costs for demolition and rebuilding can be avoided and the building can be reused faster. To assess the remaining loadbearing capacity in a scientific based way, information is necessary about the temperature distribution inside the concrete element and the residual material properties of both concrete and steel. But, at least of equal importance is a fundamental insight in how a concrete structure could behave during a heating cycle, as indirect actions due to thermal restraints can occur and cause significant cracking. These effects should be noticed during a visual inspection of the structure, however, cracks introduced by internal thermal restraints are not visible from the concrete surface. In this paper, fundamental knowledge is given about the effect of heating and cooling on the compressive strength of concrete. Diagnosis tools are discussed to obtain the temperature distribution, especially in the neighborhood of the reinforcement. Those techniques are based on the physico-chemical transformations of the cement matrix and the aggregates that occur during heating. To determine the effect of thermal restraints on the structural behavior, a methodology based on finite element methods is illustrated

Steps Towards a Method for the Formal Modeling of Dynamic Objects

Fragments of a method to formally specify object-oriented models of a universe of discourse are presented. The task of finding such models is divided into three subtasks, object classification, event specification, and the specification of the life cycle of an object. Each of these subtasks is further subdivided, and for each of the subtasks heuristics are given that can aid the analyst in deciding how to represent a particular aspect of the real world. The main sources of inspiration are Jackson System Development, algebraic specification of data- and object types, and algebraic specification of processes

S+Net: extending functional coordination with extra-functional semantics

This technical report introduces S+Net, a compositional coordination language for streaming networks with extra-functional semantics. Compositionality simplifies the specification of complex parallel and distributed applications; extra-functional semantics allow the application designer to reason about and control resource usage, performance and fault handling. The key feature of S+Net is that functional and extra-functional semantics are defined orthogonally from each other. S+Net can be seen as a simultaneous simplification and extension of the existing coordination language S-Net, that gives control of extra-functional behavior to the S-Net programmer. S+Net can also be seen as a transitional research step between S-Net and AstraKahn, another coordination language currently being designed at the University of Hertfordshire. In contrast with AstraKahn which constitutes a re-design from the ground up, S+Net preserves the basic operational semantics of S-Net and thus provides an incremental introduction of extra-functional control in an existing language.Comment: 34 pages, 11 figures, 3 table

Finite Element Modeling of the Transition Zone between Aggregat and Mortar in Concrete

Visual observations to the Interfacial Transition Zone (ITZ) between aggregate and mortar in concrete showed that this area differs significantly to the bulk mortar, further away from the ITZ. This ITZ has a higher porosity with a dissimilar crystal formation, therefore becoming the weak link in the material. In the past, concrete was seen as a two-phase material consisting of mortar and aggregates only. However, analyzing the material as a three-phase composite including the ITZ, will give a more realistic representation to its behavior. A Finite Element Model (FEM) was developed. The ITZ is modeled as a linkage element having a double spring, perpendicular and parallel to the ITZ surface. The individual load-deformation responses of these springs were obtained from laboratory tested specimens. Non-linearity is generated by evaluating the principal stresses at Gauss points, using the Kupfer-Hilsdorf-Rusch (1969) failure envelope and the CEB-FIB 2010 code. Iteration is conducted by the arc-length method developed by Riks-Wempners. The load-displacement curves resulted by the FEM were validated to laboratory tested specimens curves, to compare its effectiveness and asses the sensitivity of the model

Propagation of Ultra High Energy Cosmic Rays in Extragalactic Magnetic Fields: A view from cosmological simulations

We use the CRPropa code to simulate the propagation of ultra high energy cosmic rays (with energy $\geq 10^{18} \rm eV$ and pure proton composition) through extragalactic magnetic fields that have been simulated with the cosmological ENZO code.We test both primordial and astrophysical magnetogenesis scenarios in order to investigate the impact of different magnetic field strengths in clusters, filaments and voids on the deflection of cosmic rays propagating across cosmological distances. We also study the effect of different source distributions of cosmic rays around simulated Milky-Way like observers. Our analysis shows that the arrival spectra and anisotropy of events are rather insensitive to the distribution of extragalactic magnetic fields, while they are more affected by the clustering of sources within a $\sim 50$ Mpc distance to observers. Finally, we find that in order to reproduce the observed degree of isotropy of cosmic rays at $\sim$ EeV energies, the average magnetic fields in cosmic voids must be $\sim 0.1 \rm \ nG$, providing limits on the strength of primordial seed fields.Comment: 13 pages, 20 figure

Diffusion-reaction model for alkali-silica reaction in concrete

A new diffusion-reaction model for the potentially deleterious Alkali-Silica Reaction (ASR) process in concrete is presented. The model involves three coupled diffusion processes, two in-goingand one out-goingfrom the aggregate viewpoint. Alkali (Na+ and K+) and Calcium (Ca2+) ions diffuse “inwards”, from high molar concentration sites in the pores of the cement paste phase of the concrete specimen or at its boundaries, towards the aggregate-cement paste interfaces or the inner cracks of the aggregates. The OH- ions associated with alkali and calcium ions attack certain forms of silica in the aggregates (the “reactive silica”), dissolving it in the form of silicate ions which in turn diffuse back to the cement paste phase (“outwards”). The final potentially deleterious ASR precipitation process involves those silicate ions, plus calcium and alkalis. It takes place wherever the reactants are available by precipitating silicate hydrates of two kinds (Calcium-Silicate-Hydrates –CSH or Calcium-Alkali-Silicate-Hydrates –CASH) in a proportion depending on concentrations and temperature. The diffusion-reaction equations of this process are discretized in space and time using finite differences. An example of application in 1D is presented to illustrate the capabilities to reproduce realistically the ASR process, including some novel features not usually which are not considered in the available literature, such as the role of calcium in the development of the reaction and the inherent relationship between the reaction product composition and its swelling capacity

Review on the prediction of residual stress in welded steel components

Residual stress after welding has negative effects on the service life of welded steel components or structures. This work reviews three most commonly used methods for predicting residual stress, namely, empirical, semi-empirical and process simulation methods. Basic principles adopted by these methods are introduced. The features and limitations of each method are discussed as well. The empirical method is the most practical but its accuracy relies heavily on experiments. Mechanical theories are employed in the semi-empirical method, while other aspects, such as temperature variation and phase transformation, are simply ignored. The process simulation method has been widely used due to its capability of handling with large and complex components. To improve its accuracy and efficiency, several improvements need to be done for each simulation aspect of this method