Die Bildfeldwölbung bei magnetischen Linsen

Ohne ZusammenfassungDiese Veröffentlichung ist cin Teil der Dissertation von A. Wallraff, T. H. Aachen 1938 (D 82).Die vorstehenden Untersuchungen wurden im Elektrotechnischen Institut I der T. H. Aachen durchgeführt. Wir danken Herrn Prof. Dr.-Ing. E. h. Dr.-Ing. W. Rogowski für wertvolle Anregungen und Diskussionen. Die Gesellschaft von Freunden der Aachener Hochschule gewährte bereitwilligst ihre finanzielle Unterstützung.     

Processing of oilseeds to meal and protein flakes

The prime consideration during processing of oilseeds to meals and flakes, i.e. toasting or cooking, is the time-temperature-moisture content relationship. Protein dispersibility decrease of any of these variables, but there is a threshold value for each variable below which the denaturation rate is very slow. In general, denaturation of protein is measured by its water dispersibility, i.e., denaturation increases as protein water solubility decreases. Choice of the extraction process for oilseeds depends primarily on the oil content of the seed and the allowable protein denaturation during preparation for extraction. Seeds with oil contents up to 30% may be extracted directly in percolation extractors, with minimum protein denaturation. Higher oil content seeds must be prepressed with some denaturation or they can be extracted by an immersion process such as centrifuge battery to minimize protein denaturation. The desolventizing operation is the most critical in fixing the degree of protein denaturation, since all three pertinent variables are near or above their threshold values. The selection of the proper processing units to desolventize completely the meal but maintain desired limits will be discussed. Subsequent heat treatment after the desolventizing process may be used to denature the protein or may be minimized to prevent much further denaturation. Prompt cooling is necessary before storage to preserve the required protein denaturation values. Classification and sizing may be required to meet the meal specifications. Presented at the AOCS-AACC Short Course on “Oilseed Proteins: Chemistry, Technology and Economics. French Lick, Indiana, July 1969.     

Cement Formulations in the Calcium Phosphate H2O–H3PO4–H4P2O7 System

Despite numerous reports of calcium phosphate cement materials, a calcium cement that sets to form a matrix consisting of a pyrophosphate phase has not been reported. The formulation of such a material from the mixture of α-tricalcium phosphate (TCP), β-TCP, or tetracalcium phosphate with a solution containing pyro- and orthophosphoric acid is reported in this study. The effects of liquid and solid compositions on the setting times, compressive strengths and phase compositions of the resultant cements were investigated. It was found that cements could be produced that set to form up to 28 wt% dicalcium pyrophosphate, which appeared by comparison with Rietveld refinement and chemical methods to be entirely amorphous in nature. The solubilities of the different solid components were shown to have a marked effect on the composition of the cements. The strongest cement formulations exhibited compressive strengths comparable with those previously reported in the literature for brushite cements and set within clinically relevant time scales. This class of cement would appear to demonstrate potential as a bone replacement material.     

Vanillin-HCl method for condensed tannins: Effect of organic solvents used for extraction of tannins

Tannins are generally extracted using aqueous organic solvents, mainly methanol and acetone. The presence of various concentrations of methanol in the sample containing catechin or tannins did not alter the kinetics of their reaction, but the absorbance depended on the amount of methanol in the sample; the higher the methanol, the higher was the absorbance. Acetone reacted with acidified vanillin to produce a chromogen with _max at 548 nm, which produce a substantial error in the determination of condensed tannins. In the presence of acetone, the time courses of the reaction for catechin and tannins were different, which depended on the acetone concentration and the reaction temperature. Reaction conditions for catechin and tannins that enable their measurement in the presence of acetone are presented.     

On the ontological expressiveness of conceptual modeling grammars for service productivity management

Conceptualizing, analyzing, and optimizing service productivity is imperative to build up and to sustain competitive advantage in today’s global service economy. However, service productivity is yet to be thoroughly conceptualized and supported by IT artifacts so as to design, compute, and interpret meaningful productivity models. The purpose of this study is to evaluate the ontological expressiveness of conceptual modeling grammars for service productivity management. Due to a lack of a complete ontology for service productivity management, we compile evaluation criteria by reviewing authoritative theory. Against these criteria, a selection of conceptual modeling grammars is analyzed by reviewing the grammars’ meta models for completeness. The analysis contributes two major insights. First, theory in productivity management appears equivocal and is too unspecific to guide the design of IT artifacts. Second, conceptual modeling grammars are subject to various ontological deficiencies with respect to service productivity management. Two core implications are identified. First, service productivity theories need to be refined as design theories in order to comprehensively inform the design of IT artifacts. Second, conceptual modeling grammars must be extended and aligned with each other.     

Understanding social relationship evolution by using real-world sensing data

Mobile and pervasive computing technologies enable us to obtain real-world sensing data for sociological studies, such as exploring human behaviors and relationships. In this paper, we present a study of understanding social relationship evolution by using real-life anonymized mobile phone data. First, we define a friendship as a directed relation, i.e., person A regards another person B as his or her friend but not necessarily vice versa. Second, we recognize human friendship from a supervised learning perspective. The Support Vector Machine (SVM) approach is adopted as the inference model to predict friendship based on a variety of features extracted from the mobile phone data, including proximity, outgoing calls, outgoing text messages, incoming calls, and incoming text messages. Third, we demonstrate the social relation evolution process by using the social balance theory. For the friendship prediction, we achieved an overall recognition rate of 97.0 % by number and a class average accuracy of 89.8 %. This shows that social relationships (not only reciprocal friends and non-friends, but non-reciprocal friends) can be likely predicted by using real-world sensing data. With respect to the friendship evolution, we verified that the principles of reciprocality and transitivity play an important role in social relation evolution.     

On the reuse and recommendation of model refactoring specifications

Refactorings can be used to improve the structure of software artefacts while preserving the semantics of the encapsulated information. Various types of refactorings have been proposed and implemented for programming languages (e.g., Java or C#). With the advent of (MDSD), a wealth of modelling languages rises and the need for restructuring models similar to programs has emerged. Since parts of these modelling languages are often very similar, we consider it beneficial to reuse the core transformation steps of refactorings across languages. In this sense, reusing the abstract transformation steps and the abstract participating elements suggests itself. Previous work in this field indicates that refactorings can be specified generically to foster their reuse. However, existing approaches can handle certain types of modelling languages only and solely reuse refactorings once per language. In this paper, a novel approach based on role models to specify generic refactorings is presented. Role models are suitable for this problem since they support declaration of roles which have to be played in a certain context. Assigned to generic refactoring, contexts are different refactorings and roles are the participating elements. We discuss how this resolves the limitations of previous works, as well as how specific refactorings can be defined as extensions to generic ones. The approach was implemented in our tool Refactory based on the (EMF) and evaluated using multiple modelling languages and refactorings. In addition, this paper investigates on the recommendation of refactoring specifications. This is motivated by the fact that language designers have many possibilities to enable refactorings in their modelling languages with regard to the language structures. To overcome this problem and to support language designers in deciding which refactorings to enable, we propose a solution and a prototypical implementation.     

A Parallel SPH Implementation on Multi‐Core CPUs

This paper presents a parallel framework for simulating fluids with the Smoothed Particle Hydrodynamics (SPH) method. For low computational costs per simulation step, efficient parallel neighbourhood queries are proposed and compared. To further minimize the computing time for entire simulation sequences, strategies for maximizing the time step and the respective consequences for parallel implementations are investigated. The presented experiments illustrate that the parallel framework can efficiently compute large numbers of time steps for large scenarios. In the context of neighbourhood queries, the paper presents optimizations for two efficient instances of uniform grids, that is, spatial hashing and index sort. For implementations on parallel architectures with shared memory, the paper discusses techniques with improved cache‐hit rate and reduced memory transfer. The performance of the parallel implementations of both optimized data structures is compared. The proposed solutions focus on systems with multiple CPUs. Benefits and challenges of potential GPU implementations are only briefly discussed.     

A.I.K.E.F.: Adaptive hybrid model for space plasma simulations

The interaction between magnetized space plasmas and obstacles like comets, asteroids or planets is determined by a variety of physical processes that occur simultaneously on significantly different length and time scales. Frequently the dynamics of individual ions play a key role for the shape of the interaction region: strong velocity shear between light and heavy plasma constituents, non-Maxwellian particle distributions due to pick up and asymmetries in the magnetic field topology are crucial in determining this type of interaction. Covering these processes is beyond the scope of any Magnetohydrodynamic (MHD) model. In order to account for these effects we have developed a new adaptive hybrid code A.I.K.E.F. (Adaptive Ion-Kinetic Electron-Fluid). The code operates on Cartesian meshes that can adapt to the physical structures in both, space and time. To the authors' knowledge, there is no other adaptive hybrid simulation code in space plasma physics to the present day. Adaptivity is implemented by means of Hybrid-Block-AMR, that is individual octs are refined rather than entire blocks, where an oct is one eighth of a block. In order to account for a reasonable number of particles in each cell, particles are refined via splitting and merging. Both procedures conserve mass, momentum and kinetic energy. The code is implemented in C++ and efficiently parallelized for distributed systems by means of the Message Passing Interface (MPI). In order to demonstrate the validity of our newly developed code we have applied it to a series of fundamental test scenarios. On the one hand we demonstrate that the dispersion relation as well as the propagation characteristics of MHD and whistler mode waves are quantitatively reproduced by our simulation code. Wave propagation remains unaffected when traveling through regions that include different refinement levels. On the other hand we verify that the results obtained on high resolution uniform meshes are identical to the results from adaptive simulations that use coarse base meshes but include various levels of refinement. A remarkable speedup could be observed: the adaptive simulations required 71 times less CPU-hours than the uniform mesh simulations. Finally, we present a first series of global, three-dimensional simulations for the interaction of Mercury with the solar wind and a real time study of Titan's plasma interaction during a magnetosheath excursion.     

Reachability, observability and strict equivalence of networks of linear systems

This paper aims at a better understanding of reachability and observability properties of heterogeneous networks of linear systems. It extends prior work by Hara et al. (SICE J Control Meas Syst Integr 2:299–306, 2009), who characterized reachability for homogeneous networks of identical linear SISO systems. Our approach is based on extending the classical notion of strict system equivalence to networks of linear systems. We survey and extend known characterizations for reachability and observability for arbitrary interconnected linear MIMO systems. Both static and dynamic interconnection laws are considered, and various applications to classes of homogeneous and heterogeneous networks are derived.