Showing papers by "Münster University of Applied Sciences published in 2009"

Optimal control problems with delays in state and control variables subject to mixed control–state constraints

Abstract: Optimal control problems with delays in state and control variables are studied. Constraints are imposed as mixed control–state inequality constraints. Necessary optimality conditions in the form of Pontryagin's minimum principle are established. The proof proceeds by augmenting the delayed control problem to a nondelayed problem with mixed terminal boundary conditions to which Pontryagin's minimum principle is applicable. Discretization methods are discussed by which the delayed optimal control problem is transformed into a large-scale nonlinear programming problem. It is shown that the Lagrange multipliers associated with the programming problem provide a consistent discretization of the advanced adjoint equation for the delayed control problem. An analytical example and numerical examples from chemical engineering and economics illustrate the results. Copyright © 2008 John Wiley & Sons, Ltd.

A Closer Look Into Magnetism: Opportunities With Synchrotron Radiation

Abstract: The unique properties of synchrotron radiation, such as broad energy spectrum, variable light polarization, and flexible time structure, have made it an enormously powerful tool in the study of magnetic phenomena and materials. The refinement of experimental techniques has led to many new research opportunities, keeping up with the challenges put up by modern magnetism research. In this contribution, we review some of the recent developments in the application of synchrotron radiation and particularly soft X-rays to current problems in magnetism, and we discuss future perspectives.

Variability of surface and center position radiation dose in MDCT: Monte Carlo simulations using CTDI and anthropomorphic phantoms.

Abstract: The larger coverage afforded by wider z -axis beams in multidetector CT (MDCT) creates larger cone angles and greater beam divergence, which results in substantial surface dose variation for helical and contiguous axial scans. This study evaluates the variation of absorbed radiation dose in both cylindrical and anthropomorphic phantoms when performing helical or contiguous axial scans. The approach used here was to perform Monte Carlo simulations of a 64 slice MDCT. Simulations were performed with different radiation profiles (simulated beam widths) for a given collimation setting (nominal beam width) and for different pitch values and tube start angles. The magnitude of variation at the surface was evaluated under four different conditions: (a) a homogeneous CTDI phantom with different combinations of pitch and simulated beam widths, (b) a heterogeneous anthropomorphic phantom with one measured beam collimation and various pitch values, (c) a homogeneous CTDI phantom with fixed beam collimation and pitch, but with different tube start angles, and (d) pitch values that should minimize variations of surface dose—evaluated for both homogeneous and heterogeneous phantoms. For the CTDI phantom simulations, peripheral dose patterns showed variation with percent ripple as high as 65% when pitch is 1.5 and simulated beam width is equal to the nominal collimation. For the anterior surface dose on an anthropomorphic phantom, the percent ripple was as high as 40% when the pitch is 1.5 and simulated beam width is equal to the measured beam width. Low pitch values were shown to cause beam overlaps which created new peaks. Different x-ray tube start angles create shifts of the peripheral dose profiles. The start angle simulations showed that for a given table position, the surface dose could vary dramatically with minimum values that were 40% of the peak when all conditions are held constant except for the start angle. The last group of simulations showed that an “ideal” pitch value can be determined which reduces surface dose variations, but this pitch value must take into account the measured beam width. These results reveal the complexity of estimating surface dose and demonstrate a range of dose variability at surface positions for both homogeneous cylindrical and heterogeneous anthropomorphic phantoms. These findings have potential implications for small-sized dosimeter measurements in phantoms, such as with TLDs or small Farmer chambers.

The Synthesis and Luminescence of W6Cl12 and Mo6Cl12 Revisited

Abstract: The reduction of tungsten hexachloride with bismuth yields the new compound (BiCl)[W6Cl14]. Dissolution of this compound in HCl yields the cluster acid (H3O)2[W6Cl14]·7H2O and the new byproduct (H5O2)2[W6Cl12O6]·4H2O. The single-crystal structures of all these compounds are reported. Their appearance provides some new insight into the mechanism and apparent problems of the synthesis of pure W6Cl12. Both Mo6Cl12 and W6Cl12 are strongly red luminescent materials.

Congestion and Flow Control in the Context of the Message-Oriented Protocol SCTP

Abstract: Congestion and flow control are key mechanisms used to regulate the load in modern packet networks. The new IETF Stream Control Transmission Protocol (SCTP) inherited these algorithms from the Transmission Control Protocol (TCP). Although the principles used are the same, some issues arise from the fact that SCTP operates message-oriented whereas TCP operates byte-stream oriented. SCTP also supports bundling of multiple small user messages into one SCTP packet. As a consequence, the overall overhead of an SCTP packet depends on the user message size and the number of user messages that are bundled into the packet. RFC 4960 defining SCTP does not specify whether the message specific headers have to be considered when updating the parameters for congestion control. We will show that neglecting the additional headers when calculating outstanding bytes can lead to unfairness towards TCP connections. We will also show that incorrect handling of the additional memory needed to process each message in the flow control calculations will lead to an exhaustion of the receiver window resulting in a huge amount of unnecessary retransmissions. Based on experiments with the flow control of the SCTP implementations available in several operating systems, we will identify the issues and analyze them by using simulations. As a result, we will present solutions that will lead to fairness towards TCP and reduce the number of retransmissions substantially. Although we will focus on SCTP, the results are also true for other message-oriented protocols using bundling.

Ordnungsrahmen für die hybride Wertschöpfung

Abstract: Mit Ordnungsrahmen lassen sich hoch aggregierte Uberblicke uber die wesentli-chen Funktionsbereiche einer Domane darstellen. Der Beitrag regt die Entwick-lung eines Ordnungsrahmens fur die hybride Wertschopfung an. Mit der Konstruk-tion des Ordnungsrahmens soll eine modellbasierte Grundlage geschaffen werden, um in weiterfuhrenden Arbeiten einen strukturierten Uberblick uber die fur die hybride Wertschopfung bereits entwickelten beziehungsweise zukunftig zu entwi-ckelnden Artefakte bereitstellen zu konnen. Als Ausgangspunkt fur die Konstrukti-on eines hierfur geeigneten Ordnungsrahmens wird ein erster Vorschlag zu dessen inhaltlicher Gestaltung prasentiert. Der vorgestellte Ordnungsrahmen wird evalu-iert, indem er zur Strukturierung von in Expertenbefragungen erhobenen Artefak-ten der hybriden Wertschopfung herangezogen wird.

Electromagnetic Interference with RFID Readers in Hospitals

Abstract: Radio frequency identification (RFID) applications have become popular in many areas. RFID uses wireless technology to transmit information stored within a RFID-tag to a RFID-reader. Passive RFID-tags are powered through the received signal from the reader. Therefore the reader has to transmit its request with a certain power to bridge the gap between reader and tag. In contrast to bar-code technology this technique allows communication without requiring a line of sight.

Parallelizing OMNeT++ simulations using Xgrid

Abstract: Working with simulations, testing and validating theories often requires a large number of simulation runs. The discrete event simulation environment OMNeT++ already provides functionality for distributed computing, yet the simulated model and modules to be parallelized have to be declared manually. Apple Mac OS X comes with Xgrid support, which allows easily setting up an ad hoc grid for parallel computing. In this paper we will describe the features we had to add to OMNeT++ to be able to use Xgrid to parallelize even several thousand runs. We will point out how to use Xgrid to distribute runs of a simulation not only to multiple CPU cores but also to multiple machines without modifying the simulation itself. Our analysis will reveal that Xgrid allows to reduce the computing time almost proportional to the added parallel computing power.

Novel unimorph deformable mirror for solid state laser resonators

Abstract: We present a novel unimorph deformable mirror with a diameter of only 10 mm that will be used in adaptive resonators of high power solid state lasers The relationship between applied voltage and deformation of a unimorph mirror depends on the piezoelectric material properties, layer thicknesses, boundary conditions, and the electrode pattern An analytical equation for the deflection of the piezoelectric unimorph structure is derived, based on the electro-elastic and thin plate theory The validity of the proposed analytical model has been proven by numerical finite-element modelling and experimental results Our mirror design has been optimized to obtain the highest possible stroke and a high resonance frequency

ZnS:Mn nanoparticles conjugated to sol–gel-derived silica matrices

Abstract: Composites from ZnS:Mn nanoparticles and modified silicas are of interest for a broad range of potential applications in the form of films, structured particles, and self-assembled structures (e.g., colloidal crystals). They combine the versatility of silica sol gel chemistry with the wealth of functionalities available from doped nanoparticulate semiconductors (e.g., optical, electrical, and magnetic). In this work, ZnS:Mn nanoparticles have been prepared and modified in such a way that they can be incorporated seamlessly, either by inclusion or by covalent bonding into silicas. Functionalization was achieved through the use of silanes or thioles. Further processing by standard sol gel chemistry then either led directly to covalent conjugation with the silica network formed after condensation, or to isolated particles encapsulated in a silica shell. The results are heavily loaded (up to 30 wt%), transparent (including semiconductor particles that are smaller than 15 nm) and luminescent films, and massive bodies. In this work, the progress of nanocomposite formation was followed mainly by luminescence spectroscopy. Further work will have to address the electrical and magnetic properties of these nanocomposites as well.

Zur Qualitätssicherung bei der Ausführung von Elementwänden für wasserundurchlässige Betonkonstruktionen

Abstract: Dieser Beitrag befasst sich mit der Qualitatssicherung bei der Herstellung von Elementwanden als wasserundurchlassige Betonkonstruktionen nach der WU-Richtlinie des DAfStb. Dazu wurde im Rahmen von diversen Untersuchungen an der FH Munster wahrend der Bauausfuhrung vor allem solchen Aspekten nachgegangen, die besonders haufig bei dieser Bauweise als Schadensursache identifiziert worden waren oder bei denen die WU-Richtlinie ein vergleichsweise hohes Qualitatsniveau erwartet. Auf der Grundlage der Untersuchungsergebnisse werden abschliesend Empfehlungen zum Umgang mit Elementwanden gegeben.

A record of morbidity and medical request profiles in international humanitarian aid, taking the earthquake in Bam in Iran in 2003 as an example

Abstract: With the humanitarian work of the International Red Cross after the earthquake in Bam, Iran, it should be noted that international and national cooperation is possible according to recognised standards and concepts, and therefore morbidity records can be included uniformly in the context of day-to-day work even in post-disaster situations. The data ascertained show changes in the disease spectrum. Basic health provision according to the primary health care concept has priority in the post-disaster response (> 6 days) to the earthquake compared to more surgically oriented medical acute aid from abroad. In the international consensus conference at the beginning of January 2004, uniform morbidity recording was fixed to simple standardised disaster case definitions. The recording of traumatic, infectious and non-infectious diseases was carried out during the routine work in the outpatient facilities of the emergency response units of 3–31 January 2004. Examination was according to the following indicators: proportional morbidities and sum of the proportional morbidities. The complete examination time period included 16,677 new cases. The health facility rate only gradually increased. Temporal fluctuations in the numbers treated may be caused by secondary care of the injured, by a possible lack of accessibility (transport problems) or an increased acceptance of facilities. A written specification of the case definitions was not carried out in Bam, and so a comparison is not possible for recorded morbidities at the same time, and consistency cannot be reached for some of the data. Nine diagnoses/categories cover 98.68% of the consultations in the complete time period. Non-traumatic health problems predominate for the whole of the month. The category “others” is too high with 57.94%. Therefore, it may be assumed that certain diagnoses were overestimated, underestimated or not recognised. Vulnerable groups (children, women, the old) were not completely included. Standards and guidelines for health care in humanitarian aid exist and are of help during planning, decision finding, execution and communication. Data acquisition instruments (registering books and patient files) should be developed and standardised by national and international humanitarian groups. The recording of morbidity is a simple instrument in the context of outpatient facilities and provides valuable information for further work during disasters.

Fluoridhaltige Gäste in Alumosilicaten: Tetrafluoroborate in dem Sodalithen Na8Al6Si6O24(BF4)2

Abstract: In the course of investigations on optical properties resulting from the interaction of fluorides with alumosilicate host materials and rare earth guests, a well defined BF4– ion wasfound to be incorporated within the sodalite of composition Na8Al6Si6O24(BF4)2. The resulting cubic molecular structure, which was determined by Rietveld methods (space group P4n, a = 906.91 pm, wRp = 0.045, Rp = 0.027), contains one anion in each sodalite cage and is, contrarily to expectations, thermally stable. NMR spectroscopic investigations indicated a fast rotatory motion of the BF4– tetrahedra at room temperature and agreed with the tetrahedral BF4– ions found in IR and Raman spectra. Preliminary attempts to obtain a luminescent material by incorporation of Eu3+ through aqueous ion exchange only yielded low rare earth concentrations, giving rise to characteristic red emission lines at 581 nm (5D0 7F1) and 615 nm (5D0 7F2) in a 1:2 intensity ratio. The material unexpectedly exhibited a strong broad band emission at 520 nm after calcination under Ar, which is attributed to the formation of an Eu2+ species. Further calcination under air partially reestablished the Eu3+ emission.

Hiding the complexity of LBS

Abstract: While the demand for Location-based Services (LBS) is strongly increasing, technical laymen are not yet able to build and provide location-aware applications. This paper presents a radical simplification of the lifecycle of LBSs. An authoring toolkit enables non-technicians to easily develop context-aware mobile applications. In addition, an adaptive user interface makes the consumption of LBSs easier. The platform we present, in covering the whole LBS supply chain, is hiding the complexity of providing and consuming LBSs from the end-users.

Stock Price Dynamics of Listed Growth Companies: Evidence from the Options Market

Abstract: This paper empirically investigates the stock price dynamics implied by the valuation model proposed by Schwartz and Moon (2001) for growth companies. We test the hypothesis that the inherent stochastic process for the firm equity value better describes the actual dynamics than standard geometric Brownian motion. Because the form of the stochastic process decisively influences the values of options written on a firm's stock, we rely on price information from the options market to test the hypothesis. Contrary to our expectations, we find no evidence that the Schwartz-Moon model is superior in explaining the options market for growth companies.

Asymptotic representations for fibonacci reciprocal sums and euler’s formulas for zeta values

Abstract: Nous presentons les representations asymptotiques pour certaines sommes des reciproques des nombres de Fibonacci et des nombres de Lucas quand un parametre tend vers une valeur critique. Comme cas limite de nos resultats, nous obtenons les formules d'Euler pour les valeurs des fonctions de zeta.

Improving the recommendation of mobile services by interpreting the user's icon arrangement

Abstract: The aether soon will be pervaded with a high density of digital services for usage on mobile phones. Personalization plays a crucial role for the success and acceptance of such systems. In this paper, we present work in progress on a new approach for improving the personalization of recommender systems for pervasive services. Mobile utilization is extended from services inherent in devices to pervasive services. We describe a new concept for collaborative and content-based filtering based on the users' service rankings given by arrangement of menu icons and discuss different models for interaction with a varying icon menu.

Optimised NDIR Technology for \(^{13}{\rm CO}_2\) Breath Tests of i.e. Drug/Drug-Interactions or Gastric Emptying for Intensive Care Patients: New Diagnostic Opportunities

Abstract: Measurement devices that support CO2 breath tests on an intensive care unit should a) monitor the δ13C release curve over time for reliable data interpretation b) provide results right after sampling and c) be small and easy to handle. NDIR technology could satisfy these requirements, but is sensitive to changes in the sample O2 and CO2 content, which might occur for intensive care patients. These interferences, due to pressure broadening in the hyperfine spectrum, were corrected by a calibration method, where measured δ13C values are expressed as basal value + slope x δ13C(sample), where basal value and slope were confined to depend on the O2 and CO2 interferences. These functions were determined by fitting measured δ13C values to the corresponding model pre-dictions, with sufficient agreement between both. The slope function turned out to be linear in the interferences and the basal value function nonlinear. The calibration samples, necessary for their characterization can be generated starting from a few, user provided samples, using a machine-built-in gas mixing system. Hence, the combined \(^{12}{\rm CO}_2\) and O2 impact can be corrected by an on-site calibration method and NDIR technology can be used for bed-side monitoring in an ICU. It paves the way for clinically and economically relevant 13C-breath tests like those for gastric emptying or drug/drug interactions.

Supporting Tool for Usability Specifications

Abstract: In order to optimize the development and the de-sign of medical devices, requirement engineering is already widely being applied. Furthermore, usability engineering is considered another crucial part of developing usable and save devices.

Nachweis der Firstspaltverpressung bei zerstörungsfreien Schalendickenmessungen an Tunnelinnenschalen

Abstract: Bisherige Auswertungen bei diversen Tunnelprojekten ergaben, dass bei Tunnelinnenschalen die Firstspaltverpressung nicht immer zerstorungsfrei nachgewiesen wurde. In Bereichen, die beispielsweise durch eine freiliegende Bewehrung in der Firste instand gesetzt werden mussen, ist der Nachweis des Verpressguts von groser Bedeutung. In Laborversuchen wurde an Betonprobekorpern dieser Fragestellung durch Variation verschiedener Einflussgrosen und Parameter experimentell nachgegangen. Im Anschluss daran erfolgte die praktische Umsetzung der Versuchsergebnisse auf einer Tunnelbaustelle im Bereich von detektierten Fehlstellen im Firstbereich. Durch den Einsatz spezieller Verpressguter und Vorbehandlungen konnte die Tunnelinnenschale mit dem Verpressgut in diesem Bereich zerstorungsfrei einwandfrei nachgewiesen werden. Verification of Ridge-Gap Grouting by Measuring the Shell Thickness of the Inner Tunnel Layer by Non-Destructive Testing Previous evaluations of various tunnel projects showed results where the ridge-gap grouting of the inner tunnel shells was not always been non-destructively proven. In areas which, for example, have to be repaired through exposed reinforcement in the ridge, the proof of the grouting material is of great importance. This problem was explored experimentally in laboratory tests on concrete test specimens through variation of different actuating variables and parameters. Afterwards, the experimental results were put into practice in areas of detected flaws in the ridge area on a tunnel construction site. The inner tunnel shell with the grouting material could be proved perfectly non-destructively by using special grouting material and pre-treatments in this area.

NS-Verfolgte mit Migrationshintergrund als Patienten in der Geriatrie

Abstract: Hintergrund: Dieser Beitrag prasentiert die Ergebnisse verschiedener qualitativ-explorativer Studien zu Biographien von NS-Verfolgten mit Migrationshintergrund (Juden aus der GUS, Roma, Sinti und ehemaligen polnischen Zwangsarbeitern). Ziel ist die Erhebung der spezifischen Pflegebedurfnisse dieser vulnerablen Klientel im Hinblick auf ihre Abhangigkeit von anderen im Alter, wenn sie medizinische und pflegerische Versorgung benotigt. Methode: Semi-strukturierte Interviews auf der Basis der Grounded Theory wurden eingesetzt, um die soziale und familiale Situation der Befragten zu untersuchen. Ergebnisse: Die Angst, offen uber ihre Verfolgungserfahrungen zu sprechen, ist das hervorstechendste Merkmal all dieser Migranten. In vielen Fallen hat das Trauma die Verbindung zu ihrer Umgebung gebrochen und ausgepragte Gefuhle der Isolation und Hilflosigkeit hervorgerufen. Obwohl sie aus unterschiedlichen sozialen Milieus stammen, gibt es eine Reihe von Verhaltensweisen, die ihnen gemeinsam sind und auf eine Verfolg...

EDV-gestützte Umsetzung des Expertenstandards „Schmerzmanagement in der Pflege bei akuten oder tumorbedingten chronischen Schmerzen“

Abstract: Computer-assisted implementation of the experts standard „Pain management of acute or chronic tumor-related pain“ Summary In the year 2008 the sections 112 and 113a SGB XI have been amended. The implementation and development of expert standards have become important for the management and the nursing staff. Exemplary the following details show how the recommendations of the expert standards can be implemented. The implementation is based on the capabilities of the software TOM. It has been developed specifically designed for the nursing home. The following article is the result of a Bachelor‘s thesis (2009) that of Prof. Dr. R. Ostermann, and Prof. Dr. K. Schneider at the University of Munster has been accompanied.