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The paper recommends an approach to estimate effectively the probability of buffer overflow in high-speed communication networks, capable of carrying diverse traffic, including self-similar teletraffic, and supporting diverse levels of quality of service. Simulations with stochastic, long-range dependent self-similar traffic source models are conducted. A new efficient algorithm, based on a variant of the RESTART/LRE method, is developed and applied to accelerate the buffer overflow simulation in a finite buffer single server model under long-range dependent self-similar traffic load with different buffer sizes. Numerical examples and simulation results are shown
There is a growing trend for the use of thermo-active building systems (TABS) for the heating and cooling of buildings, because these systems are known to be very economical and efficient. However, their control is complicated due to the large thermal inertia, and their parameterization is time-consuming. With conventional TABS-control strategies, the required thermal comfort in buildings can often not be maintained, particularly if the internal heat sources are suddenly changed. This paper shows measurement results and evaluations of the operation of a novel adaptive and predictive calculation method, based on a multiple linear regression (AMLR) for the control of TABS. The measurement results are compared with the standard TABS strategy. The results show that the electrical pump energy could be reduced by more than 86%. Including the weather adjustment, it could be demonstrated that thermal energy savings of over 41% could be reached. In addition, the thermal comfort could be improved due to the possibility to specify mean room set-point temperatures. With the AMLR, comfort category I of the comfort norms ISO 7730 and DIN EN 15251 are observed in about 95% of occasions. With the standard TABS strategy, only about 24% are within category I.
Adaptive predictive control of thermo-active building systems (TABS) based on a multiple regression algorithm: First practical test. Available from: https://www.researchgate.net/publication/305903009_Adaptive_predictive_control_of_thermo-active_building_systems_TABS_based_on_a_multiple_regression_algorithm_First_practical_test [accessed Jul 7, 2017].
Agile Business Intelligence als Beispiel für ein domänenspezifisch angepasstes Vorgehensmodell
(2016)
Business-Intelligence-Systeme stellen durch ihre Unterstützung bei der Entscheidungsfindung für Unternehmen eine wichtige Rolle dar. Mit einer stetig dynamischeren Unternehmensumwelt geht daher die Anforderung nach der agilen Entwicklung dieser Systeme einher, so dass in der BI-Domäne zunehmend erfolgreich agile Methoden und Vorgehensmodelle eingesetzt werden. Die Weiterentwicklung und Anpassung von BI-Systemen ist dahingehend besonders, dass diese in der Regel langjährig gewachsenen Systemen und Strukturen betreffen, die strengen regulatorischen Rahmenbedingungen unterliegen, was eine Herausforderung für agile Vorgehensweisen darstellt. Wurden die Werte und Prinzipien des agilen Manifests [AM01] und die daraus abgeleiteten Methoden zu Beginn meist eins zu eins auf den Bereich BI übertragen, so hat sich das Verständnis von BI- Agilität als ganzheitliche Eigenschaft der BI im deutschsprachigen Raum etabliert, und agile Me- thoden wurden auf die Besonderheiten der BI-Domäne adaptiert. In diesem Beitrag werden BI-Agilität und Agile BI erläutert, ein Ordnungsrahmen für Maßnahmen zur Steigerung der BI-Agilität eingeführt sowie Herausforderungen bei Agile BI erläutert.
All business is local
(2016)
All you need is sleep
(2016)
In 21st century, the century when the humanity hopes to embark on interplanetary travel, we are yet to fully reach an understanding of our very own idiosyncratic terra incognita – the human sleep. Sleep is a highly conserved evolutionary process that constitutes approximately one third of our life, and the lack or inadequate sleep may lead to impairment across multiple cognitive domains (Tononi and Cirelli, 2014; Lim and Dinges, 2010). Sleep deprivation also leads to aberrant brain functioning, immunological and metabolic collapse, and if it is sufficiently prolonged it will ultimately lead to death (Tononi and Cirelli, 2014).
There is increasing evidence of central hyperexcitability in chronic whiplash-associated disorders (cWAD). However, little is known about how an apparently simple cervical spine injury can induce changes in cerebral processes. The present study was designed (1) to validate previous results showing alterations of regional cerebral blood flow (rCBF) in cWAD, (2) to test if central hyperexcitability reflects changes in rCBF upon non-painful stimulation of the neck, and (3) to verify our hypothesis that the missing link in understanding the underlying pathophysiology could be the close interaction between the neck and midbrain structures. For this purpose, alterations of rCBF were explored in a case-control study using H215O positron emission tomography, where each group was exposed to four different conditions, including rest and different levels of non-painful electrical stimulation of the neck. rCBF was found to be elevated in patients with cWAD in the posterior cingulate and precuneus, and decreased in the superior temporal, parahippocampal, and inferior frontal gyri, the thalamus and the insular cortex when compared with rCBF in healthy controls. No differences in rCBF were observed between different levels of electrical stimulation. The alterations in regions directly involved with pain perception and interoceptive processing indicate that cWAD symptoms might be the consequence of a mismatch during the integration of information in brain regions involved in pain processing.
n this work a mathematical model for describing the performance of lithium-ion battery electrodes consisting of porous active material particles is presented. The model represents an extension of the Newman-type model, accounting for the agglomerate structure of the active material particles, here Li(Ni1/3Co1/3Mn1/3)O2 (NCM) and Li(Ni1/3Co1/3Al1/3)O2 (NCA). To this goal, an additional pore space is introduced on the active material level. The space is filled with electrolyte and a charge-transfer reaction takes place at the liquid-solid interface within the porous active material particles. Volume-averaging techniques are used to derive the model equations. A local Thiele modulus is defined and provides an insight into the potentially limiting factors on the active material level. The introduction of a liquid-phase ion transport within the active material reduces the overall transport losses, while the additional active surface area within the agglomerate lowers the charge-transfer resistance. As a consequence, calculated discharge capacities are higher for particles modeled as agglomerates. This finding is more pronounced in the case of high C-rates
Gegenstand der hier vorgestellten Arbeit ist eine Untersuchung der gängigsten Anwendungsschicht-Protokolle für das Internet der Dinge. Sie umfasst zum einen die Recherche und den theoretischen Vergleich der Protokolle anhand vorher festgelegter Untersuchungskriterien und zum anderen einen praktisch implementierten Versuchsaufbau, der das Zusammenwirken verschiedener Protokolle veranschaulichen soll.
Zunächst wird eine kurze Einführung in das Thema „Internet der Dinge“ gegeben. Dabei wird auf die Entwicklung der letzten Jahre sowie den Stand der Technik eingegangen. Zum einen wird aufgezeigt, inwieweit sich das Thema auf die verschiedenen Bereiche des täglichen Lebens ausgebreitet hat und zum anderen welche verschiedenen Anwendungspakete diverser Software-Hersteller auf dem Markt sind. Bei der Untersuchung dieser Pakete werden die Protokolle ermittelt, die verwendet werden. Diese bilden die Menge an zu untersuchenden Protokolle für den späteren Vergleich. Um diese in einem wissenschaftlichen Rahmen miteinander vergleichen zu können, werden Kriterien als Basis der Untersuchung definiert. Anhand derer werden alle Protokolle untersucht und anschließend in einer Tabelle zusammengefasst.
Im zweiten Teil werden dann einige der untersuchten Protokolle mithilfe von diversen MCUs (Micro Controller Unit) verwendet und deren Funktionsweise/Handhabung miteinander verglichen. Dabei entsteht ein Aufbau, der zukünftigen Studierenden die Möglichkeit bietet, schnell einen Einblick in den Bereich „Internet der Dinge“ zu erhalten.
A number of design rules must be adhered to in the development and manufacturing of unmanned aerial vehicles. In this, additive manufacturing, particularly in the implementation of requirements with respect to light-weight construction and sustainability, offers several advantages compared to conventional manufacturing methods. Therefore, this article will primarily introduce and compare current concepts for sustainable design using additive manufacturing. These will, above all, consist of the production of complete fuselages and wings by means of rapid prototyping or also rapid tooling. In addition, a new concept will be introduced in which a UAV using AM can be implemented through the combination of very light components and a preferably resource-saving manufacturing method. In this process, a three-dimensional spaceframe is used in combination with a covering in the construction of the wing. Hereby, the development process for sustainable design using additive manufacturing will be analyzed and the results will be explained by means of concrete case studies. In conclusion, the results of these case studies will be compared to the latest technology regarding wing span load.
In the age data digitalization, important applications of optics and photonics based sensors and technology lie in the field of biometrics and image processing. Protecting user data in a safe and secure way is an essential task in this area. However, traditional cryptographic protocols rely heavily on computer aided computation. Secure protocols which rely only on human interactions are usually simpler to understand. In many scenarios development of such protocols are also important for ease of implementation and deployment. Visual cryptography (VC) is an encryption technique on images (or text) in which decryption is done by human visual system. In this technique, an image is encrypted into number of pieces (known as shares). When the printed shares are physically superimposed together, the image can be decrypted with human vision. Modern digital watermarking technologies can be combined with VC for image copyright protection where the shares can be watermarks (small identification) embedded in the image. Similarly, VC can be used for improving security of biometric authentication. This paper presents about design and implementation of a practical laboratory experiment based on the concept of VC for a course in media engineering. Specifically, our contribution deals with integration of VC in different schemes for applications like digital watermarking and biometric authentication in the field of optics and photonics. We describe theoretical concepts and propose our infrastructure for the experiment. Finally, we will evaluate the learning outcome of the experiment, performed by the students. © (2016) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
To successfully support private sector development in Africa by the use of trade and export promotion instruments, a comprehensive policy framework is crucial. Different institutional setups for development support show different levels of resilience and effectiveness in coping with the economic conditions they are exposed to. However, there is strong evidence that managing the interplay of three fundamental building blocks – public policy, focus areas, strategic objectives and critical success factors as well as institutions, is the key to crafting sustainable and responsive economies. Export plays a significant role in the national economy, and innovative and integrated government financing instruments have to successfully support the competitiveness of national companies in the global economy. Financing and supporting foreign trade with private businesses in Africa occupies a pivotal role, impacting from new product development and job creation in developed countries through economic growth and human development in African countries.
Nickel cobalt aluminum oxide (NCA) based lithium-ion battery electrodes exhibit a distinct asymmetry in discharge/charge behavior towards high bulk stoichiometry (low state of charge). We show that basic electrochemical relationships, that is, the Nernst equation and the Butler-Volmer equation, are able to reproduce this behavior when a two-step reaction mechanism is assumed. The two-step mechanism consists of (1) lithium-ion adsorption from the electrolyte onto the active material particle surface under electron transfer, and (2) intercalation of surface-adsorbed lithium atoms into the bulk material. The asymmetry of experimental half-cell data of an NCA electrode cycled at 0.1 C-rate can be quantitatively reproduced with this simple model. The model parameters show two alternative solutions, predicting either a saturated (highly-covered) or a depleted surface for high bulk lithiation.
Die vorliegende Bachelorarbeit behandelt das Thema „Attraktivität des Offenburger Weihnachtsmarktes als Event im Stadtmarketing“. Im ersten Teil werden Grundbegriffe und Konzepte vorgestellt und erläutert, warum Weihnachtsmärkte ein wichtiger Teil des Stadtmarketing sind. In Kooperation mit dem Stadtmarketing Offenburg wurde eine Befragung durchgeführt, um die Attraktivität des Offenburger Weihnachtsmarktes zu evaluieren. Schwerpunkte der Befragung waren Besuchsmodalitäten, Angebotsattraktivität, Aktionsräumliches Verhalten sowie Einzugsgebiet und soziodemografisches Profil der Besucher. Die Ergebnisse daraus werden im zweiten Teil der Arbeit vorgestellt. Im dritten Teil werden abschließend Empfehlungen und Ideen entwickelt, wie die Attraktivität des Offenburger Weihnachtsmarktes als Event im Stadtmarketing weiterhin auf hohem Niveau gehalten werden kann.
In der vorliegenden Arbeit wird Augmented Reality (AR) sowohl in der Theorie als auch in der Praxis ausführlich behandelt. Die Technik, welche in den letzten Jahren stark weiterentwickelt wurde, die Entwicklungsgeschichte, sowie die Projektbegleitung (aus Sicht des Auftraggebers einer AR-Anwendung) stehen im Fokus.
Neben den einleitenden Kapiteln wurde die Ausarbeitung thematisch in zwei große Bereiche unterteilt. Der erste, eher theoretische Bereich (Kapitel 2), bildet den wissenschaftlichen Teil dieser Ausarbeitung. Er beinhaltet eine Einführung in Augmented Reality und analysiert aktuelle Techniken. Auch die Funktionsweise wird aufgezeigt, um zu verstehen, was hinter den Kulissen der Anwendungen steckt. Im zweiten, praxisnahen Bereich (Kapitel 3) wird der Entstehungsprozess der Augmented Reality Applikation (App) von Kaba begleitet. Es wurde der Entstehungsprozess der App für Android und iOS ausführlich dokumentiert. Für Leser, die Probleme mit einigen Wissensbereichen haben, gibt es im Anhang eine ausführliche Literaturliste.
Auslegung eines Baukastensystems für einen Detektor zur optischen Fehlerprüfung von Mantelflächen
(2016)
Im Projekt der Abschlussarbeit wird an der Konstruktion eines sich automatisch zusammenbauenden Baukastensystems für einen Detektor in Anlagen zur optischen Teileprüfung gearbeitet. Der behandelte Detektoraufbau, bestehend aus Bildsensor, Objektiv und Beleuchtung, detektiert dabei Innen- und Außenmantelflächenfehler bei Serienteilen mit Außendurchmessern von 5 mm bis 80 mm und Höhen von 1 mm bis 60 mm. Der Detektor, auch allgemeiner als Sensor bezeichnet, weist im Konstruktionsprozess eine Problematik auf, welche durch die Erzeugung eines Baukastens gelöst werden soll.
Institute of Reliable Embedded Systems and Communication Electronics, Offenburg University of Applied Sciences, Germany has developed an automated testing environment, Automated Physical TestBeds (APTB), for analyzing the performance of wireless systems and its supporting protocols. Wireless physical networking nodes can connect to this APTB and the antenna output of this attaches with the RF waveguides. To model the RF environment this RF waveguides then establish wired connection among RF elements like splitters, attenuators and switches. In such kind of set up it’s well possible to vary the path characteristics by altering the attenuators and switches. The major advantage of using APTB is the possibility of isolated, well controlled, repeatable test environment in various conditions to run statistical analysis and even to execute regression tests. This paper provides an overview of the design and implementation of APTB, demonstrates its ability to automate test cases, and its efficiency.