Algebraic semantics for natural language: some philosophy, some applications

Information processing, when performed by an intelligent agent, draws on a wide array of knowledge sources. Among them are world knowledge, situation knowledge, conceptual knowledge and linguistic knowledge. The focus in this paper will be on the semantic knowledge which is part of the general linguistic competence of any speaker of a natural language (NL).In particular, this knowledge contains ways of organizing the linguistic ontology, i.e. the collection of heterogeneous entities that make up the domain of discourse. The representation language that is proposed here to model this knowledge stresses the structural properties of the ontology. This approach has been persued under the name of algebraic semantics.The paper starts out by explaining the term "algebraic semantics" as it is used in logic. Two senses of "algebraic" are distinguished that are called here "conceptual" and "structural". These two senses of the algebraic method are then applied to NL semantics. The conceptual part is realized by the method of structuring the domains of linguistic ontology in various ways. Thus plural entities are recognized along with mass entities and events. The common outlook here is mereological or lattice-theoretical. Some applications to the study of plurals are given that are to show the usefulness of the algebraic approach. Finally, the ontology of plurals is addressed, and comments are made on some relevant discussion of mereology in recent philosophical work. In sum, it is contended that the algebraic perspective while being of interest in semantics and philosophy proper, also fits both the spirit and the practice of much work that has been done in the Artificial Intelligence (AI) field of knowledge representation.     

Coupling Impedance in a Circular Particle Accelerator, a Particular Case: Circular Beam, Elliptic Chamber

As a first step the concept of coupling impedance (c.i.) is extended to characterize the relationship between cause and effect relevant to distinct points. Then we can exploit a new law that relates the transverse c.i. to the lonitudinal one by means of a second derivative. When cause and effect coincide we get the standard definition of c.i. At a first sight the computation of the coupling impedance for the present model seems a trivial problem. In fact the c.i. is proportional to the Green function of the relevant model, which can be found as an open series, for instance in the treatise of Morse and Feshbach. But the authors themselves warn that this series is poorly convergent and in addition should not be differentiated. We succeeded in closing the series. The problem formally seems to be solved. But this procedure could however turn out to be sterile for numerical purposes, where we obviously need series expansions, unless one finds better alternative expansions. This is the final and possibly the most important step, where a different extremely rapidly convergent expansion is found. The use of this expansion has led to the recognition of a vast number of numerical results that are synthesized in the graphic representations of this work. The longitudinal c.i. is scarsely affected by the ellipticity and excentricity of the beam, so that, unless the beam is far off the central beam position, it behaves as in a circular cross section pipe.     

Function portability of molecular dynamics on heterogeneous parallel architectures with OpenCL

Classical molecular dynamics simulation for atomistic systems is implemented in OpenCL and benchmarked on a variety of different hardware platforms. Modifying the number of particles and system size in the study provides insight into characteristics of parallel compute platforms, where latency, data transfer, memory access characteristics and compute intense work can be identified as fingerprints in benchmark runs. Data layouts are compared, for which the access of structure-of-arrays shows best performance in most cases. It is demonstrated that function portability can be achieved straightforwardly with OpenCL, while performance portability lacks behind as various architectures strongly depend on specific vectorisation optimisation.     

The Metrology Light Source of PTB – a Source for THz Radiation

The Physikalisch-Technische Bundesanstalt (PTB), the German national metrology institute, operates the low-energy electron storage ring Metrology Light Source (MLS) in Berlin-Adlershof in close cooperation with the Helmholtz-Zentrum Berlin (HZB). The MLS is designed and prepared for a low-α machine optics mode based on a sextupole and octupole correction scheme, for the production of coherent synchrotron radiation in the far-IR and THz region. In our contribution we present commissioning results, which clearly indicate that the MLS, in combination with dedicated beamlines, offers intense, stable, and well-focused THz radiation. We discuss the planned use of the MLS for metrology in the THz spectral range.     

Glued detectors for the CRESST-II experiment

The Cryogenic Rare Event Search with Superconducting Thermometers Phase II (CRESST-II) at the L.N.G.S in Italy is searching for Dark Matter using low-temperature calorimeters. These detectors allow to discriminate different particles by simultaneous measurement of phonons and scintillation light. The sensors used consist of superconducting tungsten thin-film thermometers, which measure the thermal effect of the phonons created in an attached absorber crystal. It has been observed that the scintillation of the CaWO₄ absorber degrades during the process of depositing the tungsten film. In order to prevent this, a new technique for producing the detectors was investigated. This technique might also be valuable by expanding the range of scintillator materials suitable for producing a Dark Matter detector.     

Parallel simulation of Brownian dynamics on shared memory systems with OpenMP and Unified Parallel C

The simulation of particle dynamics is an essential method to analyze and predict the behavior of molecules in a given medium. This work presents the design and implementation of a parallel simulation of Brownian dynamics with hydrodynamic interactions for shared memory systems using two approaches: (1) OpenMP directives and (2) the Partitioned Global Address Space (PGAS) paradigm with the Unified Parallel C (UPC) language. The structure of the code is described, and different techniques for work distribution are analyzed in terms of efficiency, in order to select the most suitable strategy for each part of the simulation. Additionally, performance results have been collected from two representative NUMA systems, and they are studied and compared against the original sequential code.