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Kommentar zum Artikel "Arthur Willis Goodspeed" von Otto Glasser, veröffentlicht in Science Vol. 98, Issue 2540, Seite 219 (doi.org/10.1126/science.98.2536.125).
Die Pulmonalvenenisolation (PVI) mithilfe von Kryoballonkathetern ist eine anerkannte Methode zur Behandlung von Vorhofflimmern (AF). Diese Methode bietet eine kürzere Behandlungsdauer als die klassische Therapie durch die Hochfrequenz- (HF) Ablation. Ziel dieser Studie war es, verschie-dene Kryoballonkatheter, HF-Ablationskatheter und Ösophaguskatheter in ein Herzrhythmusmodell zu integrieren und mit statischer und dynamischer Simulation elektrische und thermische Felder bei PVI unter Vorhofflimmern zu untersuchen.
Die Katheterablation mit Hochfrequenzstrom (HF) ist der Goldstandard für die Therapie vieler kardi-aler Tachyarrhythmien. Bei der HF-Ablation entstehen Temperaturen zwischen 50 °C und 70 °C, wo-durch bestimmte Strukturen im Herzgewebe gezielt zerstört werden können. Ziel der Studie ist, die HF-Ablation und deren Wärmeausbreitung in Bezug auf die zugeführte Leistung mit unterschiedli-chem Elektrodenmaterial und Elektrodengröße bei supraventrikülären Tachykardien zu simulieren.
Hintergrund: Die Pulmonalvenenisolation (PVI) mit Hilfe von Kryoballonkathetern ist eine anerkannte Methode zur Behandlung von Vorhofflimmern (AF). Diese Methode bietet eine kürzere Behandlungsdauer als die klassische Therapie durch die Hochfrequenzablation (HF). Ziel dieser Studie war es, verschiedene Kryoballonkatheter, HF-Katheter und Ösophaguskatheter in ein Herzrhythmusmodell zu integrieren und mittels statischer und dynamischer Simulation elektrische und thermische Felder bei PVI unter Vorhofflimmern zu untersuchen.
Methodik: Die Modellierung und Simulation erfolgte mit der elektromagnetischen und thermischen Simulationssoftware CST (CST Darmstadt). Zwei Kryoballons, ein HF-Ablationskatheter und ein Ösophaguskatheter wurden auf der Grundlage der technischen Handbücher der Hersteller Medtronic und Osypka modelliert. Der 23 mm Kryoballon und ein kreisförmiger Mappingkatheter wurden in das Offenburger Herzrhythmusmodell integriert, insbesondere die left inferior pulmonary vein (LIPV) zur Simulation der thermischen Feldausbreitung während einer PVI. Die Simulation einer PVI mit HF-Energie wurde mit dem integrierten HF-Ablationskatheter in der Nähe der LIPV durchgeführt. Der im Herzrhythmusmodell platzierte TO8 Ösophaguskatheter ermöglichte die Ableitung linksatrialer elektrischer Felder bei AF und die Analyse thermischer Felder während PVI.
Ergebnisse: Elektrische Felder konnten bei Sinusrhythmus und AF mit einem AF-Fokus in der LIVP statisch und dynamisch im Herzen und Ösophagus simuliert werden. Bei einer simulierten 20 Sekunden Applikation eines Kryoballon-Katheters bei -50°C wurde eine Temperatur von -24°C in einer Tiefe von 0,5 mm im Myokard gemessen. In einer Tiefe von 1 mm betrug die Temperatur -3°C, bei 2 mm Tiefe 18°C und bei 3 mm Tiefe 29°C. Unter der 15 sekündigen Anwendung eines HF-Katheters mit einer 8-mm-Elektrode und einer Leistung von 5 W bei 420 kHz betrug die Temperatur an der Spitze der Elektrode 110°C. In einer Tiefe von 0,5 mm im Myokard betrug die Temperatur 75°C, in einer Tiefe von 1 mm 58°C, in einer Tiefe von 2 mm 45°C und in einer Tiefe von 3 mm 38°C. Im Ösophagus konnte bei den meisten Simulationen eine konstante Temperatur von 37°C gemessen und die Gefahr einer Ösophagus-Fistel ausgeschlossen werden. Bei Kryoablation der LIPV wurde eine Abkühlung des Ösophagus auf 30°C gemessen.
Schlussfolgerungen: Die Herzrhythmussimulation elektrischer und thermaler Felder ermöglichen mit Anwendung unterschiedlicher Herzkatheter eine statische und dynamische Simulation von PVI durch Kryoablation, HF-Ablation und Temperaturanalyse im Ösophagus. Unter Einbeziehung von MRT- oder CT-Daten können elektrische und thermale Simulationen möglicherweise zur Optimierung von PVIs genutzt werden.
The visualization of heart rhythm disturbance and atrial fibrillation therapy allows the optimization of new cardiac catheter ablations. With the simulation software CST (Computer Simulation Technology, Darmstadt) electromagnetic and thermal simulations can be carried out to analyze and optimize different heart rhythm disturbance and cardiac catheters for pulmonary vein isolation. Another form of visualization is provided by haptic, three-dimensional print models. These models can be produced using an additive manufacturing method, such as a 3d printer. The aim of the study was to produce a 3d print of the Offenburg heart rhythm model with a representation of an atrial fibrillation ablation procedure to improve the visualization of simulation of cardiac catheter ablation. The basis of 3d printing was the Offenburg heart rhythm model and the associated simulation of cryoablation of the pulmonary vein. The thermal simulation shows the pulmonary vein isolation of the left inferior pulmonary vein with the cryoballoon catheter Arctic Front Advance™ from Medtronic. After running through the simulation, the thermal propagation during the procedure was shown in the form of different colors. The three-dimensional print models were constructed on the base of the described simulation in a CAD program. Four different 3d printers are available for this purpose in a rapid prototyping laboratory at the University of Applied Science Offenburg. Two different printing processes were used and a final print model with additional representation of the esophagus and internal esophagus catheter was also prepared for printing. With the help of the thermal simulation results and the subsequent evaluation, it was possible to draw a conclusion about the propagation of the cold emanating from the catheter in the myocardium and the surrounding tissue. It was measured that just 3 mm from the balloon surface into the myocardium the temperature dropped to 25 °C. The simulation model was printed using two 3d printing methods. Both methods, as well as the different printing materials offer different advantages and disadvantages. All relevant parts, especially the balloon catheter and the conduction, are realistically represented. Only the thermal propagation in the form of different colors is not shown on this model. Three-dimensional heart rhythm models as well as virtual simulations allow very clear visualization of complex cardiac rhythm therapy and atrial fibrillation treatment methods. The printed models can be used for optimization and demonstration of cryoballoon catheter ablation in patients with atrial fibrillation.
Spinal cord stimulation (SCS) is the most commonly used technique of neurostimulation. It involves the stimulation of the spinal cord and is therefore used to treat chronic pain. The existing esophageal catheters are used for temperature monitoring during an electrophysiology study with ablation and transesophageal echocardiography. The aim of the study was to model the spine and new esophageal electrodes for the transesophageal electrical pacing of the spinal cord, and to integrate them in the Offenburg heart rhythm model for the static and dynamic simulation of transesophageal neurostimulation. The modeling and simulation were both performed with the electromagnetic and thermal simulation software CST (Computer Simulation Technology, Darmstadt). Two new esophageal catheters were modelled as well as a thoracic spine based on the dimensions of a human skeleton. The simulation of directed transesophageal neurostimulation is performed using the esophageal balloon catheter with an electric pacing potential of 5 V and a trapezoidal signal. A potential of 4.33 V can be measured directly at the electrode, 3.71 V in the myocardium at a depth of 2 mm, 2.68 V in the thoracic vertebra at a depth of 10 mm, 2.1 V in the thoracic vertebra at a depth of 50 mm and 2.09 V in the spinal cord at a depth of 70 mm. The relation between the voltage delivered to the electrodes and the voltage applied to the spinal cord is linear. Virtual heart rhythm and catheter models as well as the simulation of electrical pacing fields and electrical sensing fields allow the static and dynamic simulation of directed transesophageal electrical pacing of the spinal cord. The 3D simulation of the electrical sensing and pacing fields may be used to optimize transesophageal neurostimulation.
Proton Exchange Membrane Fuel Cell (PEMFC) is one of the most promising technologies for sustainable energy production due to the high power density, low operative temperature and more convenient use for several applications. Nevertheless, the high generated current that characterizes PEMFC requires a specific power conditioning. In addition, specific controller must be designed to fit with system operative points changing associated with the variation of this high current. To deal with this challenge, in this paper, an electrochemical system composed of a Proton Exchange Membrane Fuel Cell (PEMFC) feeding via two phases IBC has been proposed and investigated. For robustness, the used IBC for fuel cell voltage regulation is controlled by linear quadratic regulator (LQR). Then, genetic algorithms technique is applied to optimize the LQR controller parameters giving optimal control coefficients and can if necessary be adjusted according to each working situation change. The model of the entire system is studied using Matlab/Simulink environment. The simulation’s comparative standard and robustness results both demonstrate that the proposed GA-based LQR controller outperforms the conventional PI in terms of performance metrics (overshoot reduction: between 58.93% and 97.09%; response time reduction: between 56.40% and 77.00% and ripple reduction: between 84.00% and 94.86%).
Energy and environment continue to be major issues of human mankind. This holds true on the regional, the national, and the global level. And it is one of the problems, where engineers and scientists in conjunction with political will and people's awareness, can find new approaches and solutions to save the natural resources and to make their use more efficient.
The automatic classification of the modulation format of a detected signal is the intermediate step between signal detection and demodulation. If neither the transmitted data nor other signal parameters such as the frequency offset, phase offset and timing information are known, then automatic modulation classification (AMC) is a challenging task in radio monitoring systems. The approach of clustering algorithms is a new trend in AMC for digital modulations. A novel algorithm called `highest constellation pattern matching' is introduced to identify quadrature amplitude modulation and phase shift keying signals. The obtained simulation and measurement results outperform the existing algorithms for AMC based on clustering. Finally, it is shown that the proposed algorithm works in a real monitoring environment.
Neuroprosthetics 2.0
(2019)
For e-commerce retailers it is crucial to present their products both informatively and attractively. Virtual reality (VR) systems represent a new marketing tool that supports customers in their decision-making process and offers an extraordinary product experience. Despite these advantages, the use of this technology for e-commerce retailers is also associated with risks, namely cybersickness. The aim of the study is to investigate the occurrence of cybersickness in the context of the customer’s perceived enjoyment and the perceived challenge of a VR product presentation. Based on a conceptual research framework, a laboratory study with 533 participants was conducted to determine the influence of these factors on the occurrence of cybersickness. The results demonstrate that the perceived challenge has a substantially stronger impact on the occurrence of cybersickness, which can only be partially reduced by perceived enjoyment. When realizing VR applications in general and VR product presentations in particular, e-commerce retailers should therefore first minimize possible challenges instead of focusing primarily on entertainment aspects of such applications.
Die vorliegende Master-Thesis befasst sich mit dem Thema Handel. In der Arbeit wird der Bereich des Multi-Channel-Handels genauer durchleuchtet. Es wird aufgezeigt, wie der Zukunft des Handels weltweit und in Deutschland aussehen wird.
Der Handel wird besonders heute sehr vom Konsumierendenverhalten beeinflusst. Unternehmen passen sich mehr als je zuvor an Wünsche und Anforderungen der Zielgruppe an. Dies ist wichtig für Handelsunternehmen um wettbewerbsfähig und profitabel zu bleiben, vor allem in einem immer aggressiver werdenden Wettbewerbskampf um Konsumierende. In dieser Arbeit wird dargestellt, wie sich die Customer Journey und der Kaufprozess der Konsumierenden verändert hat und flexibler geworden ist. Es gibt nicht mehr nur einen Weg, wie potentielle Verkaufsinteressierende zu Kundschaft wird. Die Kundschaft lässt sich nicht mehr von Unternehmen leiten, sondern möchte eigenständig und selbstbestimmt zwischen verschiedenen Absatzkanälen und Endgeräten wechseln. Daher ist ein verknüpftes Multi-Channel-System für Handelsunternehmen wichtig. In dieser Arbeit soll zudem gezeigt werden, dass die Omni-Channel-Strategie die Strategie der Zukunft ist und wie der Begriff des New Retail sowohl den Online-Handel, als auch den stationären Handel prägen wird.
Online-Handelsunternehmen wie Amazon, Alibaba und Bonprix haben bereits verstanden, dass der stationäre Handel nicht „ausstirbt“, sondern durch eine intelligente Verknüpfung mit dem Online-Handel sehr zukunftsweisend gemacht werden kann. Daher wird in dieser Arbeit auch gezeigt, wie sich pure E-Commerce-Unternehmen in den Innenstädten und Einkaufszentren in den USA, China und Deutschland ausbreiten und damit eine Omni-Channel-Strategie schaffen.
Researchers are developing new GNSS receivers and antennas based on an innovative signal-processing scheme to significantly improve GNSS tracking reliability and accuracy under degraded signal conditions. It is based on the principles of synthetic-aperture radar. Like in a multi-antenna phased array receiver, GNSS signals from different spatial locations are combined coherently forming an optimized synthetic antenna-gain pattern. The method is implemented in a real-time PC-based software receiver and works with GPS, GLONASS, and Galileo signals. Multiple frequencies are generally supported. The idea of synthetic-aperture processing is realized as a coherent summation of correlation values of each satellite over the so-called beamforming interval. Each correlation value is multiplied with a phase factor. For example, the phase factor can be chosen to compensate for the relative antenna motion over the beam-forming interval and the resulting sum of the scaled correlation values represents a coherent correlation value maximizing the line of sight signal power.
The paper proposes a system architecture for charging infrastructure that serves the requirements of future fleets of shared-use electric vehicles in urban scenarios. The focus of the development is on the interfaces to central stakeholders such as mobility service providers, distribution network operators and utilities. The main concept of the proposed system is the adherence to a stringent resource-oriented design approach, following the design principles of the Representational State Transfer (REST) architectural software style for distributed systems. This design approach is used from the cloud-based services down to the implementation of the charging infrastructure's control algorithms. Focusing on the resources of the various entities simplifies the implementation of their interactions, compared to the explicit declaration of services that are available. The system design ensures that the charging infrastructure is open to all users and generates a benefit beyond basic charging operations. Integration in emerging smart markets is done via open web-based interfaces. These allow for the generation of an added value of concrete services for shared-use electric mobility. A link to the field of grid operation is proposed using the ISO/IEC 61850 telecontrol standard. The smart meter capabilities of the charging stations can be used to gain additional information on the current state of the distribution grid. As an exemplary service a load management service for a fleet of shared-use electric vehicles is going to be implemented.
Die Analyse von Engpässen im Güterverkehr ist eine wichtige Voraussetzung, um zukünftige Heraus-forderungen der Infrastrukturplanung und Logistik bewältigen zu können. Im Rahmen des EU-Projekts Code24 sollen Strategien für die Behandlung zukünftiger Herausforderungen im Schienengüterverkehr im wichtigsten europäischen Güterverkehrskorridor Rotterdam-Genua entwickelt werden. Hierfür sind Infor-mationen über Zugzahlen und die Kapazitätsauslastung auf einzelnen Streckenabschnitten eine wichtige Voraussetzung.
The CO2 uptake on nanoscale AlO(OH) hollow spheres (260 mg g−1) as a new material is comparable to that on many metal–organic frameworks although their specific surface area is much lower (530 m2 g¬1versus 1500–6000 m2g¬1). Suited temperature–pressure cycles allow for reversible storage and separation of CO2 while the CO2 uptake is 4.3-times higher as compared to N2.
The study from Mehrazin et al. in HJNM 2011; 14(3): 243-50 on the neuropsychology, morphological computerized tomography (CT) and functional neuroimaging with 99mTc-labelled ethylene cystein-ate dimer single-photon emission tomography (SPET) in mild trau-matic brain injury (MTBI) is an interesting new approach to a disease condition which is often neglected or denied. Related to the above, we may note that the French composer Maurice Ravel (1875-1937), who suffered from Pick ́s disease with primary progressive apha-sia, had a taxi accident in 1932, with a mild concussion, perhaps an MTBI. Apart from the dysphasia and beginning apraxia, which Rav-el had already 5 years prior to the taxi accident, these symptoms exacerbated-the dysphasia became a progressive aphasia-and he developed additional severe deficits in concentration and atten-tion after the accident. It has also been suspected that this accident may have triggered Ravel ́s agraphia the unability to write down any new composition beyond the date of the taxi accident, a condi-tion that Ravel himself described as unacceptable and which made him feel very sad as his mind was full of ideas. Due to the deterio-ration of his health, which can also be seen in his appearance on late photographs, Ravel consulted the famous neurosurgeon Prof. Clovis Vincent. Vincent, who suspected a hydrocephalus, opened Ravel ́s skull on December 19, 1937, showing a normal brain. Soon after surgery Ravel died. In conclusion, a SPET/CT approach com-bined with a brain perfusion analysis using statistical parametric mapping might be the recommendable approach today for mild traumatic brain injury.
In this paper, the multiaxial formulation of a mechanism-based model for fatigue life prediction is presented whichcan be applied to low-cycle fatigue (LCF) and thermomechanical fatigue (TMF) problems in which high-cycle fa-tigue loadings are superimposed. The model assumes that crack growth is the lifetime limiting mechanism and thatthe crack advance in a loading cycleda/dNcorrelates with the cyclic crack-tip opening displacement ΔCTOD.The multiaxial formulation makes use of fracture mechanics solutions and thus, does not need additional modelparameters quantifying the effect of the multiaxiality. Furthermore, the model includes contributions of HCF on ΔCTODand assesses the effect of the direction of the HCF loadings with respect to LCF or TMF loadings inthe life prediction. The model is implemented into the finite-element program ABAQUS. It is applied to predictthe fatigue life of a thermomechanically loaded notched specimen that should represent the situation between theinlet and outlet bore holes of cylinder heads. A good correlation of the predicted and the measured fatigue lives isobtained.
The newly synthesized Zn4O-based MOF 3∞[Zn4(μ4-O){(Metrz-pba)2mPh}3]·8 DMF (1·8 DMF) of rare tungsten carbide (acs) topology exhibits a porosity of 43% and remarkably high thermal stability up to 430 °C. Single crystal X-ray structure analyses could be performed using as-synthesized as well as desolvated crystals. Besides the solvothermal synthesis of single crystals a scalable synthesis of microcrystalline material of the MOF is reported. Combined TG-MS and solid state NMR measurements reveal the presence of mobile DMF molecules in the pore system of the framework. Adsorption measurements confirm that the pore structure is fully accessible for nitrogen molecules at 77 K. The adsorptive pore volume of 0.41 cm3 g−1 correlates well with the pore volume of 0.43 cm3 g−1 estimated from the single crystal structure.
The suffix-free-prefix-free hash function construction and its indifferentiability security analysis
(2012)
In this paper, we observe that in the seminal work on indifferentiability analysis of iterated hash functions by Coron et al. and in subsequent works, the initial value (IV) of hash functions is fixed. In addition, these indifferentiability results do not depend on the Merkle–Damgård (MD) strengthening in the padding functionality of the hash functions. We propose a generic n-bit-iterated hash function framework based on an n-bit compression function called suffix-free-prefix-free (SFPF) that works for arbitrary IVs and does not possess MD strengthening. We formally prove that SFPF is indifferentiable from a random oracle (RO) when the compression function is viewed as a fixed input-length random oracle (FIL-RO). We show that some hash function constructions proposed in the literature fit in the SFPF framework while others that do not fit in this framework are not indifferentiable from a RO. We also show that the SFPF hash function framework with the provision of MD strengthening generalizes any n-bit-iterated hash function based on an n-bit compression function and with an n-bit chaining value that is proven indifferentiable from a RO.
In this work the adsorption of CO2 and CH4 on a series of isoreticular microporous metal–organic frameworks based on 2-substituted imidazolate-4-amide-5-imidates, IFP-1–IFP-6 (IFP = Imidazolate Framework Potsdam), is studied firstly by pure gas adsorption at 273 K. All experimental isotherms can be nicely described by using the Tòth isotherm model and show the preferred adsorption of CO2 over CH4. At low pressures the Tòth isotherm equation exhibits a Henry region, wherefore Henry's law constants for CO2 and CH4 uptake could be determined and ideal selectivity αCO2/CH4 has been calculated. Secondly, selectivities were calculated from mixture data by using nearly equimolar binary mixtures of both gases by a volumetric–chromatographic method to examine the IFPs. Results showed the reliability of the selectivity calculation. Values of αCO2/CH4 around 7.5 for IFP-5 indicate that this material shows much better selectivities than IFP-1, IFP-2, IFP-3, IFP-4 and IFP-6 with slightly lower selectivity αCO2/CH4 = 4–6. The preferred adsorption of CO2 over CH4 especially of IFP-5 and IFP-4 makes these materials suitable for gas separation application.
A survey in 2000 revealed that only about 30% of the prescriptions in the European pediatric population were on the basis of evidence-based medicine (EbM). Less for radiopharmaceuticals and principally for diagnostics, radiologists throughout Europe are referred to the pediatric guidelines of the European Association of Nuclear Medicine (EANM), as none of the frequently used tracers have been evaluated in clinical trials in the different pediatric subgroups. Following a resolution to address the lack of EbM in children, the European Commission published the Pediatric Regulation EC 1901/2006 and its amendment EC 1902/2006, effective from 2007. This regulation foresees the development of evidence-based medicine in the pediatric population. This is effected through a set of principles like the mandatory pediatric investigation plan (PIP) to be included with the market authorization application (MAA), and the pediatric use market authorization (PUMA) for off-patent pharmaceuticals, and to a very small part radiopharmaceuticals with funding possibilities for pediatric-specific research through the 7th Framework Programme (7FP) of the European Union.
Routine nuclear cardiology examinations indicate heart rate, cardiac rhythm, the height of cardiac pulse and respiration rhythm. It would be of interest to study whether these data, especially if the same tests are repeated, can indicate patients’ well being in the future and perhaps patients’ life span, other factors being equal. Related old theories and suggestions are mentioned. Furthermore, some drugs like I-f channel antagonists and stress tests testing cardiac reserves could support such a study.
The Humboldt digital library (HDL) represents an innovative system to access the works and legacy of Alexander von Humboldt in a digital form on the Internet (www.avhumboldt.net). It contributes to the key question about how to present interconnected data in an appropriate form using information technologies. The HDL has been created as a dynamic digital library with the capability of connecting multilingual and multimedia data from diverse online archives. Humboldt’s volumes have become available, but beyond that any relevant information related to the observations of Humboldt, even outside the works can become immediately accessible. This makes it possible to recognize natural changes and compare Humboldt’s descriptions with recent situations. The technology we have developed addresses the issues of sustainability and makes it possible to detect changes in the environment since the time of Humboldt’s observations.
The present study describes medium-chain-length polyhydroxyalkanoates (mcl-PHAs) production by the Pseudomonas Gl01 strain isolated from mixed microbial communities utilized for PHAs synthesis. A two-step fedbatch fermentation was conducted with glucose and waste rapeseed oil as the main carbon source for obtaining cell growth and mcl-PHAs accumulation, respectively. The results show that the Pseudomonas Gl01 strain is capable of growing and accumulating mcl-PHAs using a waste oily carbon source. The biomass value reached 3.0 g/l of CDW with 20% of PHAs content within 48 h of cultivation. The polymer was purified from lyophilized cells and analyzed by gas chromatography (GC). The results revealed that the monomeric composition of the obtained polyesters depended on the available substrate. When glucose was used in the growth phase, 3-hydroxyundecanoate and 3- hydroxydodecanoate were found in the polymer composition, whereas in the PHAs-accumulating stage, the Pseudomonas Gl01 strain synthesized mcl-PHAs consisting mainly of 3- hydroxyoctanoate and 3-hydroxydecanoate. The transcriptional analysis using reverse-transcription real-time PCR reaction revealed that the phaC1 gene could be transcribed simultaneously to the phaZ gene.
An analytical and numerical study of the wobbling dynamics of friction disks is presented. Of particular interest is the excitation mechanism taking into account two contrarian effects both originating in dry friction: the circulatory terms describing the energy input due to the sliding contacts and the friction induced damping which stabilizes the system. Balance of these terms determines the instability domain in the parameter space. It is shown that there is a slip threshold so that, if the slip is under this limit, the system remains stable. If the slip is larger than this limit, then the criterion of stability is determined by the relation between the friction coefficient and the internal damping. The limit cycle appearing in the unstable domain is also investigated. It is shown that the limit cycle can be described as a kind of a regular reverse precession of the wobbling disc. Its amplitude is limited by the geometric nonlinearity and partial contact loss. Analytic results are compared with numeric simulations.
Regarding the importance of adsorptive removal of carbon monoxide from hydrogen-rich mixtures for novel applications (e.g. fuel cells), this work provides a series of experimental data on adsorption isotherms and breakthrough curves of carbon monoxide. Three recently developed 5A zeolites and one commercial activated carbon were used as adsorbents. Isotherms were measured gravimetrically at temperatures of 278–313 K and pressures up to 0.85 MPa. Breakthrough curves of CO were obtained from dynamic column measurements at temperatures of 298–301 K, pressures ranging from 0.1 MPa to ca. 6 MPa and concentrations of CO in H2/CO mixtures of 5–17.5 mol%. A simple mathematical model was developed to simulate breakthrough curves on adsorbent beds using measured and calculated data as inputs. The number of parameters and the use of correlations to evaluate them were restricted in order to focus the importance of measured values. For the given assumptions and simplifications, the results show that the model predictions agree satisfactorily with the experimental data at the different operating conditions applied.
Thin-layer chromatography is a rapid and reliable working method for quantification of mycotoxins which is suitable for checking EC legislation aflatoxin limits for dried figs without an RP-18 pre-column cleaning step. We describe normal-phase chromatography on silica gel plates with 2.4:0.05:0.1:0.05 ( v/v ) methyl t -butyl ether-water-methanol-cyclohexane as mobile phase and reversed-phase chromatography on RP-18 plates with methanol-4% aqueous ZnSO 4 solution-ethyl methyl ketone 15:15:3 ( v/v ) as mobile phase. Sample pretreatment was by modified QuEChERS (Quick, Easy, Cheap, Effective, Rugged, Safe) extraction with tetrahydrofuran or acetone. NaCl was used as QuEChERS salt. Response was a linear function of amount chromatographed in the ranges 3 to 100 pg per zone for aflatoxins B 2 and G 2 , 10 to 350 pg per zone for the aflatoxins B 1 and G 1 , and 0.25 to 2.5 ng per zone for ochratoxin A. Quantification limits for the aflatoxins were between 13 and 35 pg per zone (equivalent to 1.5 and 2.4 ppb, taking the pre-treatment procedure into account). Ochratoxin A was detectable with a limit of quantification of 970 pg per zone, corresponding to 56 ppb in the sample. Normal phase and RP-18 separations work rapidly, reliably, and at low cost. They are also suitable for checking the content of the mycotoxins patulin, penicillic acid, zearalenone, and deoxynivalenol.
Hydrogen chloride and sulphur dioxide are gaseous by-products of chloridization processes that employ thionyl chloride. Absorption would be a feasible method to clean the rich gas stream. Two serial connectable absorption columns were equipped with the latest generation of packings to effect product recovery. Therefore, several tests concerning the baffle properties had to be performed. In the first experimental section, the hydraulic parameters pressure drop and hold-up were investigated. The hold up value range of the new baffles Raschig Super Ring (RSR) and Raschig Super Pak (RSP) was clearly below that of the former installed packing, Raschig Ring (RR). However, due to the low maximal flow rate, the range of stagnation and flooding could not be measured. The maximal measured pressure drop value was, for RR, only 0.3 mbar/m, which is very low compared to the measurement error. Batch experiments, where the waste gases were produced by reaction of thionyl chloride in water, showed that for the steady state determination of the separation steps it is advisable to use just one column in simplex mode with a defined gas supply by a gas cylinder. The HTU determination for RSR and a HCl/H2O system delivered a value of HTUHCl,OG = 0.14 ± 0.01 m with a variation coefficient of 24.2%.
There are some existing Java benchmarks, application benchmarks as well as micro benchmarks or mixture both of them,such as: Java Grande, Spec98, CaffeMark, HBech, etc. But none of them deal with behaviors of multi tasks operating systems. As a result, the achieved outputs are not satisfied for performance evaluation engineers. Behaviors of multi tasks operating systems are based on a schedule management which is employed in these systems. Different processes can have different priority to share the same resources. The time is measured by estimating from applications started to it is finished does not reflect the real time value which the system need for running those programs. New approach to this problem should be done. Having said that, in this paper we present a new Java benchmark, named FHOJ benchmark, which directly deals with multi tasks behaviors of a system. Our study shows that in some cases, results from FHOJ benchmark are far more reliable in comparison with some existing Java benchmarks.
HPTLC on amino plates, with simple heating of the plates for derivatization, has been used for quantification of glucosamine in nutritional supplements. On heating the plate glucosamine reacts to form a compound which strongly absorbs light between 305 and 330 nm, with weak fluorescence. The reaction product can be detected sensitively either by absorption of light or by fluorescence detection. The detection limit in absorption mode is approximately 25 ng per spot. In fluorescence mode a detection limit of 15 ng is achievable. A calibration plot for absorption detection is linear in the range 25 to 4000 ng glucosamine. The derivative formed from glucosamine by heating is stable for months, and the relative standard deviation is 1.64% for 600 ng glucosamine. The amounts of glucosamine found in nutritional supplements were in agreement with the label declarations.
The identification and quantification of compounds in the gas phase becomes of increasing interest in the context of environmental protection, as well as in the analytical field. In this respect, the high extinction coefficients of vapours and gases in the ultraviolet wavelength region allow a very sensitive measurement system. In addition, the increased performance of the components necessary for setting up a measurement system, such as fibres, light sources and detectors has been improved. In particular the light sources and detectors offer improved stability, and the deep UV performance and solarisation resistance of fused silica fibres allow have been significantly optimized in the past years. Therefore a compact and reliable detection system with high measuring accuracy is developed. Within this paper possible applications of the system under development and recent results will be discussed.
The identification and quantification of compounds in the gas phase becomes of increasing interest in the context of environmental protection, as well as in the analytical field. In this respect, the high extinction coefficients of vapours and gases in the ultraviolet wavelength region allow a very sensitive measurement system. In addition, the increased performance of the components necessary for setting up a measurement system, such as fibres, light sources and detectors has been improved. In particular the light sources and detectors offer improved stability, and the deep UV performance and solarisation resistance of fused silica fibres allow have been significantly optimized in the past years. Therefore a compact and reliable detection system with high measuring accuracy is developed. Within this paper possible applications of the system under development and recent results will be discussed.
The Division Industrial Chemistry of the Swiss Chemical Society organizes periodically a two-day event for the post-graduate education of its members. This event is known as the Freiburger Symposium. This year it focussed on sustainable chemical production. The twelve talks covered the following aspects: ethical needs for sustainability standards, the required, attained, and yet to be attained sustainability goals in chemical industry. Diverse case studies showed the highly developed awareness about the sustainability issue within the chemical community.
Lattice vibrations and electronic transitions in the rare-earth metals: Praseodymium under pressure
(2004)
Praseodymium was investigated by Raman spectroscopy under pressure. A negative pressure shift of the E2g mode is observed in the dhcp phase, which indicates that the initial structural sequence hcp→Sm−type→dhcp→fcc as a whole in the regular lanthanides is associated with a softening of this mode. The pressure response of the phonon modes, observed in the monoclinic and α-uranium phases, where 4f bonding becomes important, is characteristic for anisotropic bonding properties.
The structure of the separation bubble that appears in the secondary meridional flow between two coaxially rotating spheres at low and finite Reynolds number (Re) is considered. The low Re analytical study was motivated by recognizing some errors in the analytical work on this problem by Arunachalam and Majhi (1987, Q. Jl Mech. Appl. Math., 40, 47) whilst the finite Re experimental study was motivated by the desire to observe the separation bubble in the laboratory. Though the finite Re experiments were performed in a confined apparatus, they exhibit the qualitative features of the low Re theoretical predictions for the axisymmetric separation bubble that encloses two toroidal vortices symmetrically disposed above and below the mid‐plane of sphere separation, but strong effects of confinement are apparent. The flows observed include (i) a wall‐attached bubble symmetric about the mid‐plane at low Re, (ii) symmetric free‐standing bubbles at moderate Re, and (iii) an asymmetric bubble with flow separating from one sphere and attaching to the support shaft between the spheres at sufficiently high Re.
Formal verification (FV) is considered by many to be complicated and to require considerable mathematical knowledge for successful application. We have developed a methodology in which we have added formal verification to the verification process without requiring any knowledge of formal verification languages. We use only finite-state machine notation, which is familiar and intuitive to designers. Another problem associated with formal verification is state-space explosion. If that occurs, no result is returned; our method switches to random simulation after one hour without results, and no effort is lost. We have compared FV against random simulation with respect to development time, and our results indicate that FV is at least as fast as random simulation. FV is superior in terms of verification quality, however, because it is exhaustive.
Es wird eine Fallstudie vorgestellt, die die Visualisierung von Geschäftsdaten nach dem International Business Communication Standard IBCS (Hichert & Faisst 2016 / 2017) auf der cloudbasierten Plattform SAP Analytics Cloud umsetzt. Mit der Fallstudie soll die Frage beantwortet werden, ob IBCS im Rahmen einer Lehreinheit mit hohem praktischem Anteil mit SAP Analytics Cloud umgesetzt werden kann. Darüber hinaus soll der generelle Einsatz von SAP Analytics Cloud für die Lehre im Analytics-Umfeld evaluiert werden.
In this paper pathophysiological interrelated deactivation/activation phenomena are set out in the example of whiplash injury. These phenomena could have been underestimated in previous positron emission tomography studies as their focus was on hypoperfusion rather than hyperperfusion. In addition, statistical parametric mapping analysis of cerebral studies is normally not fine-tuned to special interesting areas rather than to obvious clusters of difference.
Im Datenbankenlabor der Fakultät M+I wurde ein neuer Laborversuch implementiert. Ziel war es die dokumentenorientierte Datenbank MongoDB so zu adressieren, dass Studenten und Studentinnen den Umgang mit diesem System erlernen können. Dazu wurden die wichtigsten Merkmale und Eigenschaften des Systems zusammengetragen und in einem Laborversuch zusammengefasst. Zugleich sollte der administrative Aufwand zur Durchführung des Laborversuches einfach sein. Deshalb wurde das Containersystem Docker verwendet, um die MongoDB auf dem Server zu installieren und adressieren zu können.
Die zunehmende Digitalisierung macht den Einsatz von E-Mail-Marketing in Unternehmen fast unumgänglich. Um einen effektiven Kundenkontakt zu gewährleisten müssen Unternehmen auf den Versand von Newslettern setzen, die in regelmäßigen Abständen an den Kundenstamm herausgeschickt werden. Ein Newsletter beinhaltet Informationen, die von Relevanz für die Kundschaft ist. Die Thematik kann ein Überblick über Geschehnisse des Unternehmens sein, aber auch Events und Rabattaktionen sind möglich. In der heutigen Zeit stehen eine Vielzahl an Tools zur Verfügung, um mit Hilfe von Newslettern den Kontakt zum Kunden und zur Kundin zu pflegen. Die Generierung von E-Mail-Adressen, sowie die Kampagnenerstellung sind solche Teilgebiete. Ebenso das Tracking und der automatisierte Versand der E-Mails. Längst nicht alle Unternehmen nutzen die Vorteile des Kommunikationskanals und von denjenigen, die den Kanal nutzen, ist fast jeder Zweite nicht zufrieden mit seiner E-Mail-Marketing Strategie.1 Außerdem gibt es eine Menge Richtlinien, die es zu beachten gilt, wenn das E-Mail-Marketing genutzt wird, ansonsten kann es zu Abmahnungen kommen.
Die vorliegende Bachelorthesis stellt ein Leitfaden für die Umsetzung von Newslettern im B2C-Bereich dar. Dabei bietet die Arbeit einen Rundumblick in das Thema, sodass Unternehmen dadurch in der Lage sind einen Newsletter aufzubauen und somit den Kontakt zu ihren Abonnenten und Abonnentinnen erfolgreich zu halten. Unterthemen, die in dieser Thesis beleuchtet werden, sind zum einen die Planung und Zielsetzung eines Newsletters, anschließend die erfolgreiche Generierung von E-Mail-Adressen. Zum anderen auch die technischen und rechtlichen Anforderungen an die Newsletter. Außerdem werden die Gestaltungselemente und das Controlling behandelt. Größtenteils werden die Fragen innerhalb dieser Thesis mit Hilfe von relevanter Fachliteratur beantwortet. Zusätzlich werden die Ergebnisse durch eine Umfrage, sowie eine Eye-Tracking Untersuchung unterstützt.
Die ältere Bevölkerung wächst kontinuierlich an. Dadurch erhöht sich auch der Bedarf an Pflegeleistungen und Pflegepersonal stetig. Allerdings herrscht ein großer Mangel an Pflegekräften. Die vorliegende Arbeit liegt dieser Problematik zugrunde. Ein Aspekt für eine mögliche Problemlösung ist der Einsatz sozialer Roboter, zur Betreuung älterer Menschen und Unterstützung des Pflegepersonals. Ziel dieser Arbeit war es daher, die Akzeptanz älterer Menschen und dem Personal in verschiedenen Pflegeeinrichtungen gegenüber sozialen Robotern sowie gewünschte Fähigkeiten dessen zu untersuchen.
Zu diesem Zweck wurden zum einen 67 ältere Personen mithilfe eines Fragebogens zur Thematik befragt. Zum anderen wurden sieben qualitative Interviews mit Angestellten in Pflegeheimen geführt.
Virtual reality in the hotel industry: assessing the acceptance of immersive hotel presentation
(2019)
In the hotel industry, it is crucial to reduce the inherent information asymmetry with regard to the goods offered. This asymmetry can be minimised through the use of smartphone-based virtual reality applications (SBVRs), which allow virtual simulation of real experiences and thus enable more efficient information retrieval. The aim of the study is to determine for the first time the user acceptance of these immersive hotel presentations for assessing the performance of a travel accommodation. For this purpose, the Technology Acceptance Model (TAM) was used to explain the acceptance behaviour for this new technology. A virtual reality application was specially developed, in which the participants could explore a hotel virtually. A total of 569 participants took part in the study. The structural equation model and the hypotheses were tested using a Partial Least Squares (PLS) analysis. The results illustrate that the immersive product experience leads to more efficient information gathering. The perceived usefulness significantly affects the attitude towards using the technology as well as the intention to use it. In contrast to the traditional TAM, the perceived ease of use of SBVRs has no effect on the perceived usefulness or attitude towards using the technology.
Unternehmerische Entscheidungen sollten auf einer angemessene Informationsgrundlage basieren. Diese rechtliche Aufforderung stellt Geschäftsleiter in der Praxis vor erhebliche Herausforderungen, die insbesondere die Erstellung von Prognosen betreffen. Um hier einen Unterstützungsbeitrag zu leisten, wird eine Heuristik vorgestellt, die das Treffen prognosebezogener Informationsentscheidungen anleitet. Die Heuristik übernimmt aus der Multiattributiven Nutzentheorie die Empfehlung, Informationsentscheidungen als Gesamtheit aus Zielfunktion und Bewertungsfunktion zu modellieren. In der Zielfunktion werden die Ziele der Informationsentscheidungen von den allgemeinen Unternehmenszielen wie etwa dem Gewinn gelöst. Statt dessen wird auf die Bewirkung besonderer Qualitätseigenschaften von Informationen abgestellt; das sind Vollständigkeit, Genauigkeit und Zuverlässigkeit. Daraus ergeben sich die beiden grundlegenden Ziele von Informationsentscheidungen: „Maximierung der Informationsqualität“ und „Minimierung der Informationskosten“. Auf dieser Grundlage besteht für die Bewertungsfunktion die Herausforderung darin, die positiven Nutzenwirkungen aus einer Vergrößerung der Informationsqualität abzuwägen gegen die negativen Nutzenwirkungen, die aus einer damit verbundenen Vergrößerung der Informationskosten resultieren. Um diese Herausforderung zu bewältigen, wird ein iteratives Verfahren aus sequentiell zu treffenden und in diesem Sinne inkrementellen Informationsentscheidungen vorgeschlagen. Wertvoll ist diese Heuristik einerseits in entscheidungstheoretischer Hinsicht, weil sie vorliegende methodische Überlegungen zum Treffen von Informationsentscheidungen erweitert. Vor allem aber besitzt die Heuristik einen praktischen Wert für Geschäftsleiter, da ihre Anwendung bessere Voraussetzungen dafür schafft, der rechtlichen Pflicht zur ordentlichen und gewissenhaften Geschäftsführung zu genügen.
Das Ziel der vorliegenden Bachelorarbeit war es, die Fähigkeiten des LDC1000 EVM von Texas Instruments (TI) zur hochauflösenden induktiven Distanzmessung, integriert in ein Kraftmesssystem, als Alternative zur Dehnungsmessung mit Dehnungsmessstreifen zu untersuchen. Hierzu wurden zunächst Versuche an einem Wegmessaufbau bezüglich Auflösung, Rauschverhalten und der Qualitätsmerkmale für messtechnische Systeme wie Nullpunktstabilität, Linearität und Hystereseverhalten durchgeführt. Anschließend diente eine entworfene Druckmessdose, mit applizierten Dehnungsmessstreifen als Referenz, zur weiteren Untersuchung der Qualitätsmerkmale und zur Optimierung des LDC1000-Systems. Als Messobjekte zur Abstandsmessung kamen die Werkstoffe AlMgSi0,5, St37, AlCu4Mg1 und 1.4305 verschiedener Geometrien zum Einsatz. Die Ergebnisse bestätigen die Angabe von TI zur Sub-Mikrometer-Auflösung des Systems, ein relativ hoher Rauschanteil beschränkt allerdings die Genauigkeit. Die Resultate der Untersuchungen von Nullpunktstabilität und Hystereseverhalten lassen einen Einsatz im Bereich der Kraftmesstechnik unter gewissen Voraussetzungen zu, das nichtlineare Verhalten der induktiven Wegmessung hingegen macht eine nachträgliche Linearisierung der Messwerte unumgänglich. Diese Bachelorarbeit richtet sich an all diejenigen, die sich detallierter mit Alternativen zur Dehnungsmessung auseinandersetzen oder genauere Untersuchungen zum LDC1000 EVM von TI durchführen.
The development of secure software systems is of ever-increasing importance. While software companies often invest large amounts of resources into the upkeeping and general security properties of large-scale applications when in production, they appear to neglect utilizing threat modeling in the earlier stages of the software development lifecycle. When applied during the design phase of development, and continuously during development iterations, threat modeling can help in following a “Security by Design” approach. This approach allows issues relating to IT security to be found early during development, reducing the need for later improvement – and thus saving resources in the long term. In this thesis the current state of threat modeling is investigated. Based on this analysis, requirements for a new tool are derived. These requirements are then used to develop a new tool, called OVVL, which utilizes all main components of current threat modeling methodologies, as well as functionality not available in existing solutions. After documenting the development process and OVVL in general, this newly developed tool is used to conduct two case studies in the field of e-commerce and IoT.
Die Arbeit verfolgt das Ziel zu eruieren, welche Visual-Social-Mediakommunikationsstrategie, insbesondere unter Beobachtung der Visual-Social-Plattformen, aktuell am erfolgversprechendsten für die Hochzeitsmedienbranche ist.
Die neu gewonnenen Erkenntnisse der Ausarbeitung und die anschließenden Handlungsempfehlungen sollen als Leitfaden für eine sinnvolle und Erfolg versprechende Visual Social Marketingkommunikationsstrategie für Hochzeitsblogs/ -Blogazine genutzt werden können.
Der Leitfaden soll auf die Entwicklungen in der Zielgruppe eine passende Reaktion bieten und die Online-Marketingkommunikationsstrategie insbesondere der von Hochzeitsblogs und – Blogazine zukunftsfähig bereichern.
Existing ultrasonic stress evaluation methods utilize the acoustoelastic effect for bulk waves propagating in volume, which is unsuitable for a surface treated material, possessing a significant variation in material properties with depth. With knowledge of nonlinear elastic parameters – third-order elastic constants (TOEC) close to the surface of the sample, the acoustoelastic effect might be used with surface acoustic waves. This work is focused on the development of an independent method of TOEC measurement using the effect of nonlinear surface acoustic waves scattering – i.e. the effect of elastic waves interaction in a nonlinear medium.
In this paper, the possible three wave interactions of surface guided waves and bulk waves are described and formulae for the efficiency of harmonic generation and mode mixing are derived. A comparison of the efficiency of surface waves scattering in an isotropic medium for different interaction types is carried out with the help of nonlinear perturbation theory. First results for surface and bulk wave mixing with known second- and third-order elastic constants are shown.