Development of an In Situ Measurement Device for Obtaining Material Thermal Properties

This thesis presents a methodology for measuring thermal properties in situ, with a special focus on obtaining properties of layered stack-ups commonly used in armored vehicle components. The technique involves attaching a thermal source to the surface of a component, measuring the heat flux transferred between the source and the component, and measuring the surface temperature response. The material properties of the component can subsequently be determined from measurement of the transient heat flux and temperature response at the surface alone. Experiments involving multilayered specimens show that the surface temperature response to a sinusoidal heat flux forcing function is also sinusoidal. A frequency domain analysis shows that sinusoidal thermal excitation produces a gain and phase shift behavior typical of linear systems. Additionally, this analysis shows that the material properties of sub-surface layers affect the frequency response function at the surface of a particular stack-up. The methodology involves coupling a thermal simulation tool with an optimization algorithm to determine the material properties from temperature and heat flux measurement data. Use of a sinusoidal forcing function not only provides a mechanism to perform the frequency domain analysis described above, but sinusoids also have the practical benefit of reducing the need for instrumentation of the backside of the component. Heat losses can be minimized by alternately injecting and extracting heat on the front surface, as long as sufficiently high frequencies are used.

Comparative study of four retentive anchor systems for implant supported overdentures--retention force changes

OBJECTIVES: Wear of attachments leads to a loss of retention and potentially reduces the function of complete dentures. This study evaluated the retention force changes of different prefabricated attachment systems for implant-supported overdentures to estimate the wear constancy and applicability in clinical practice. METHODS: Four prefabricated attachment systems were tested [Group SG: retentive ball attachment (Straumann, Switzerland) with gold matrix, Group ST: retentive ball attachment (Straumann, Switzerland) with titanium spring matrix, Group IB: UNOR i-Ball with Ecco matrix (UNOR, Switzerland) and Group IMZ: IMZ-TwinPlus ball attachment with gold matrix (DENTSPLY Friadent, Germany)]. Ten samples of each system were subjected to 10,000 insertion-separation cycles. RESULTS: Results showed that all types of attachments showed wear, which led to a loss of retention force after an initial increase at the beginning of the wear simulation. Attachments with a plastic retention insert or gold matrices underwent the smallest changes in retention force. The titanium spring system showed the largest changes in retention force and a greater variation between the different cycles and specimen. This behaviour is probably caused by a large fitting tolerance of the titanium spring. CONCLUSIONS: Attachment systems which possess a male and female component of different material composition are preferable. They show smaller changes in the retention force. For retention force increase and wear compensation, an attachment system should be adjustable.

Das Internet der Dinge unter dem Aspekt der Selbststeuerung-Ein Überblick

In den letzten Jahren wurde die Vision einer Welt smarter Alltagsgegenstände unter den Begriffen wie Ubiquitous Computing, Pervasive Computing und Ambient Intelligence in der Öffentlichkeit wahrgenommen. Die smarten Gegenstände sollen mit digitaler Logik, Sensorik und der Möglichkeit zur Vernetzung ausgestattet werden. Somit bilden sie ein „Internet der Dinge“, in dem der Computer als eigenständiges Gerät verschwindet und in den Objekten der physischen Welt aufgeht. Während auf der einen Seite die Vision des „Internet der Dinge“ durch die weiter anhaltenden Fortschritte in der Informatik, Mikroelektronik, Kommunikationstechnik und Materialwissenschaft zumindest aus technischer Sicht wahrscheinlich mittelfristig realisiert werden kann, müssen auf der anderen Seite die damit zusammenhängenden ökonomischen, rechtlichen und sozialen Fragen geklärt werden. Zur Weiterentwicklung und Realisierung der Vision des „Internet der Dinge“ wurde erstmals vom AutoID-Center das EPC-Konzept entwickelt, welches auf globale netzbasierte Informationsstandards setzt und heute von EPCglobal weiterentwickelt und umgesetzt wird. Der EPC erlaubt es, umfassende Produktinformationen über das Internet zur Verfügung zu stellen. Die RFID-Technologie stellt dabei die wichtigste Grundlage des „Internet der Dinge“ dar, da sie die Brücke zwischen der physischen Welt der Produkte und der virtuellen Welt der digitalen Daten schlägt. Die Objekte, die mit RFID-Transpondern ausgestattet sind, können miteinander kommunizieren und beispielsweise ihren Weg durch die Prozesskette finden. So können sie dann mit Hilfe der auf den RFID-Transpondern gespeicherten Informationen Förderanlagen oder sonstige Maschinen ohne menschliches Eingreifen selbstständig steuern.

RFID Transponders : Link between information and material flows. How reliable are identification procedures?

Along with the growing complexity of logistic chains the demand for transparency of informations has increased. The use of intelligent RFID-Technology offers the possibility to optimize and control all capacities in use, since it enables the identification and tracking of goods alongside the entire supply chain. Every single product can be located at any given time and a multitude of current and historical data can be transferred. The interaction of the flow of material and the flow of information between the various process steps can be optimized by using RFID-Technology since it guarantees that all required data is available at the right time and at the right place. The local accessibility and convertibility of data allows a flexible, decentralised control of logistic systems. As additional advantages of RFID-Components can be considered that they are individually writable and that their identification can be achieved over considerable distances even if there is no intervisibility between tag and reader. The use of RFID-Transponder opens up new potentials regarding process security, reduction of logistic costs or availability of products. These advantages depend on reliability of the identification processes. The undisputed potentials that are made accessible by the use of RFID-Elements can only be beneficial when the informations that are decentralised and attached to goods and loading equipment can be reliably retrieved at the required points. The communication between tag and reader can be influenced by different materials such as metal, that can disturbed or complicate the radio contact. The communications reliability is subject of various tests and experiments that analyse the effects of different filling materials as well as different alignments of tags on the loading equipment.

Modeling and Vibration Suppression for Telescopic Systems of Structural Members with Clearance

Telescopic systems of structural members with clearance are found in many applications, e.g., mobile cranes, rack feeders, fork lifters, stacker cranes (see Figure 1). Operating these machines, undesirable vibrations may reduce the performance and increase safety problems. Therefore, this contribution has the aim to reduce these harmful vibrations. For a better understanding, the dynamic behaviour of these constructions is analysed. The main interest is the overlapping area of each two sections of the above described systems (see markings in Figure 1) which is investigated by measurements and by computations. A test rig is constructed to determine the dynamic behaviour by measuring fundamental vibrations and higher frequent oscillations, damping coefficients, special appearances and more. For an appropriate physical model, the governing boundary value problem is derived by applying Hamilton’s principle and a classical discretisation procedure is used to generate a coupled system of nonlinear ordinary differential equations as the corresponding truncated mathematical model. On the basis of this model, a controller concept for preventing harmful vibrations is developed.

Reliability of evaluations for the choice of system solutions at the example of automated order-picking systems for bagged goods

There is a steadily increasing pressure on cost-savings and productivity growth in sectors of order-picking such that the wish for rationalization by automation is rising. Special problems are faced trying to automatize handling operations of order-picking articles packed in bags. The mechanical properties of the objects and their hard-to-predict shape and position represent obstacles and are complicating handling operations. A systematic approach in system design is required. This article deals with the properties of such products under aspects of difficulties arising in automated handling and points out a useful system development methodology.

Utilizing the full Capacity of Sorting Systems with new Infeed Technology

Utilisation of sorting systems’ maximum performance demands continuous conveying of goods by infeed lines to sorters. This is the case especially for sorters with one single infeed line, because the sorters’ performance is limited by the performance of the infeed line. Within this paper different infeed line constructions at the Rotary Sorter with diverse performances will be presented. The focus lies on a specific conveying system to synchronise the goods with the sorter by a performance of 6000 pieces per hour with one dynamic infeed line. By this means there is no extensive adjustment control of serial conveyors in the infeed line any longer.

Energy and weight reduction in hoisting systems with magnetic traction sheaves

At the Chair of Logistics Engineering, TU Dresden, a particular focus is research and development of magnetic traction sheaves. Therein the main fundamentals of these special sheaves are determined for applications in different fields such as elevators, several kinds of winches, hoists and cranes. In the current research project “energy balance of magnetic traction sheaves”, the dynamic behaviour of systems with magnetic traction sheaves was investigated. The research focused on theoretical and practical examinations of energy balance. Moreover, a new approach for dimensioning magnetic traction sheave systems is presented. It is a project of the Research Foundation Intralogistics / Material Handling and Logistics (IFL), which is funded through the AiF under the program of Industrial Collective Research for SMEs (IGF) by the Federal Ministry of Economics and Technology (BMWi).

Novel calculation method for chain conveyor systems

Sidexflexing plastic chains are used increasingly in material handling due to their highly flexible conveying design and layout options. These systems are often equipped with so called modular belts. Due to their specific force transmission, detailed calculation methods are not yet available. In the following, a generally valid calculation approach is derived and its difference to existing solutions shown by examples.

Intelligente Hochleistungsförderkette aus Kunststoff

Im folgenden Beitrag wird die Entwicklung einer metallverstärkten Kunststoffgleitkette mit integrierter Sensorik skizziert. Der Focus der Arbeit liegt unter anderem auf Untersuchungen zum Werkstoffverbundverhalten zwischen Metall und Kunststoff, der Adaptierung von Mikroelektronik in einzelne Kettenglieder, einer großserientauglichen Fertigungstechnologie für hybride Leichtbaukomponenten, sowie die Erarbeitung von Gestaltungsgrundsätzen und Logistikkonzepten für die Produktion von Leichtbaukomponenten mittels fusionierter Prozesse.

Entwicklung eines Versuchsfelds für große Systeme intelligenter Behälter

Im Rahmen dieses Artikels werden aktuelle Forschungsarbeiten zum Einsatz von Energy-Harvesting und Ultra-Low-Power-Geräten in Materialflusssystemen beschrieben. Ein besonderes Augenmerk wird auf die inBin-Plattform, das Energy-Harvesting und deren Auswirkungen auf die Leistungsverfügbarkeit gelegt. Dazu werden die Hardwareplattform und Architektur der inBin-Plattform sowie der Aufbau eines Versuchsfelds detailliert erläutert. Des Weiteren wird ein Ansatz zur Modellierung und Simulation von Systemen mit einer großen Anzahl von inBin-Plattformen vorgestellt. Darüber hinaus werden die Ergebnisse zweier simulierter Szenarien und mögliche Folgen für die Planung zukünftiger Materialflusssysteme betrachtet.

Development of a novel material flow simulation model for the integration of spatial and process relevant information

Simulation techniques are almost indispensable in the analysis of complex systems. Materials- and related information flow processes in logistics often possess such complexity. Further problem arise as the processes change over time and pose a Big Data problem as well. To cope with these issues adaptive simulations are more and more frequently used. This paper presents a few relevant advanced simulation models and intro-duces a novel model structure, which unifies modelling of geometrical relations and time processes. This way the process structure and their geometric relations can be handled in a well understandable and transparent way. Capabilities and applicability of the model is also presented via a demonstrational example.

Enterprise Integration of Smart Objects using Semantic Service Descriptions

Integrating physical objects (smart objects) and enterprise IT systems is still a labor intensive, mainly manual task done by domain experts. On one hand, enterprise IT backend systems are based on service oriented architectures (SOA) and driven by business rule engines or business process execution engines. Smart objects on the other hand are often programmed at very low levels. In this paper we describe an approach that makes the integration of smart objects with such backends systems easier. We introduce semantic endpoint descriptions based on Linked USDL. Furthermore, we show how different communication patterns can be integrated into these endpoint descriptions. The strength of our endpoint descriptions is that they can be used to automatically create REST or SOAP endpoints for enterprise systems, even if which they are not able to talk to the smart objects directly. We evaluate our proposed solution with CoAP, UDP and 6LoWPAN, as we anticipate the industry converge towards these standards. Nonetheless, our approach also allows easy integration with backend systems, even if no standardized protocol is used.

Comparative antibacterial efficacies of hydrodynamic and ultrasonic irrigation systems in vitro

INTRODUCTION To ensure root canal treatment success, endodontic microbiota should be efficiently reduced. The in vitro bactericidal effects of a hydrodynamic system and a passive ultrasonic irrigation system were compared. METHODS Single-rooted extracted teeth (n = 250) were contaminated with suspensions of Enterococcus faecalis ATCC 29212, mixed aerobic cultures, or mixed anaerobic cultures. First, the antibacterial effects of the hydrodynamic system (RinsEndo), a passive ultrasonic irrigation system (Piezo smart), and manual rinsing with 0.9% NaCl (the control) were compared. Colony-forming units were counted. Second, the 2 systems were used with 1.5% sodium hypochlorite (NaOCl) alone or NaOCl + 0.2% chlorhexidine (CHX). The colony-forming units in the treated and untreated roots were determined during a period of 5 days. RESULTS Both irrigation systems reduced bacterial numbers more effectively than manual rinsing (P < .001). With NaCl, ultrasonic activated irrigation reduced bacterial counts significantly better than hydrodynamic irrigation (P = .042). The NaOCl + CHX combination was more effective than NaOCl alone for both systems (P < .001), but hydrodynamic irrigation was more effective with NaOCl + CHX than the passive ultrasonic irrigation system. CONCLUSIONS Both irrigation systems, when combined with NaOCl + CHX, removed bacteria from root canals.