A new camless electrohydraulic valve train concept for combustion engines was developed at Empa (Swiss Federal Laboratories for Materials Science and Technology, Dübendorf, Switzerland) and tested on a spark ignition passenger car engine. Besides full flexibility with regard to lift and timing of the engine gas exchange valves it features robustness, simplicity and in particular a low own drive power need due to a maximum of hydraulic energy recuperation. The engine test results confirm substantial efficiency gains in classical as well as in hybrid power trains while also maintaining additional advantages. The system also has the potential to become a key element for load control of piston based compressors and expanders, reciprocating Joule Cycle engines and derivable future electricity storage systems.

This paper presents a conceptual study aiming to improve the compactness of electro-hydraulic compact drives (ECD ). In most current ECD architectures, gas accumulators are used as volume compensators for the flow imbalance emerging whenever asymmetric single rod cylinders are used. To stay within a required reservoir pressure range typically from two to four bar, a large gas volume is required, compromising system compactness. Combining conventional ECD architectures with a bootstrap reservoir offers a greater degree of freedom in system design, which enables downsizing or avoidance of the gas volume. Another potential benefit by including a bootstrap reservoir is the possibility of elevating the backpressure of the ECD thus enhancing drive stiffness, expanding the application range and market acceptance. Based on an open analysis of the solution space occurring when introducing a bootstrap reservoir, three system architectures are selected for a conceptual study. The results show that the downsizing potential is strongly dependent on the maximum friction force and the area ratio of the bootstrap reservoir pistons, while a linear analysis reveals that for some system architectures the bootstrap reservoir may severely influence the system dynamics. Simulation results confirm the functionality of the proposed system architectures, and show that a potential for downsizing/avoiding the gas volume, as well as increasing the ECD stiffness is present.

This paper discusses the potential of centralized or decentralized electro-hydraulic (EH)-drives in comparison to conventional hydraulic systems. The systems are presented in diagrams covering the major electric and hydraulic components for an exemplary application, but also include specific technical data like the sizing of the components according to power, pressure, rotational speeds etc. In a second step, all systems are compared and evaluated based on criteria like design effort, energy saving potential, controllability, and servicing and maintenance of the machine. The resulting effects on fuel consumption are summarized as well. Finally, an evaluation of the potential of EH-drives in construction machinery and a derivation of the demands for future customization of electro-hydraulic linear drives is given on the basis of a SWOT-analysis from the point of view of a construction machinery OEM.

Animals exploit soft structures to move smoothly and effectively in complex natural environments. These capabilities have inspired robotic engineers to incorporate soft actuating technologies into their designs. Developing soft muscle-like actuation technology is one of the grand challenges in the creation of soft-body robots that can move, deform their body, and modulate body stiffness. This paper presents the development of smart pneumatic McKibben muscles woven and reinforced by using conductive insulated wires to equip the muscles with an inherent sensing capability, in which the deformation of the muscles can be effectively measured by calculating the change of wire inductance. Sensing performance of a variety of weaving angles is investigated. The ideal McKibben muscle models are used for analysing muscle performance and sensing accuracy. The experimental results show that the contraction of the muscles is proportional to the measured change of inductance. This relationship is applied to a PID control system to control the contraction of smart muscles in simulation, and good control performance is achieved. The creation of smart muscles with an inherent sensing capability and a good controllability is promising for operation of future soft robots.

Magnetic Shape Memory (MSM) alloys show a superelastic behaviour with possible deformation rates up to 6% until 12% and a sufficient lifetime performance [1, 2]. In this paper, a passive application for a superelastic Ni-Mn-Ga-alloy is presented by using the MSM element as an accurately defined inner friction in a system of a multistable actuator, in particular a multistable proportional valve. The multistable valve is characterized by a currentless holding of the valve displacement in any position of the stroke. This circumstance makes the concept a very low energy consumption valve, compared to conventional proportional valves with solenoid actuators. The new aspect of a rigid connection of MSM Materials enables an absorption of tension as well as compressive forces. To realize an applicable controlling valve, a simple and effective controlling strategy has been implemented. Due to the stabilizing effect of the MSM element, an accurate controlling of the valve stroke and the usage for example as a pressure-, mass-flow or temperature-controlling valve was made possible. Furthermore, some potential applications in pneumatics as well as in hydraulics are presented.

In the automotive industry, the Safety Function-FMEA according to ISO 26262 and its application to functional safety relevant systems is a well-established process in the form of Automotive Safety Integrity Levels (ASILs). These represent the failure mitigation that must be applied to ensure an acceptable residual risk of malfunctioning behaviour. The DIN EN ISO 13849 (ISO 13849) already describes a process to reduce risks for machines which starts with a Hazard And Risk Analysis (HARA) as described in DIN EN ISO 12100 and concludes with the Safety Requirements Specification (SRS). The SRS is a functional and technical safety concept defining requirements and guidelines to make sure the design conforms to defined safety goals. ISO 13849 lists important faults and failures for various technologies. The defined Safety Functions (SFs) can be classified in corresponding categories that lead to the particular hardware/system structure. This applies to mechatronic systems consisting of at least one sensor, one control unit and one actuator to monitor the system and effect a response in case of failure. Compared to the methods described in ISO 13849, the Safety Function-FMEA allows systematic identification of additional failures resulting from combinations of effects, rather than only listing the main failure causes. Based on the complexity of the machines it is highly recommended to perform a Safety Function-FMEA as a complementary method to assess and improve the overall safety of machinery.

At the end of the 17th century, a small enameled cross was discovered in one of the royal graves in Saint Bendt's church in Danish Ringsted. According to the record of the administrator of the Danish Royal Treasury, the cross was found in the grave of the Danish Queen Dagmar - the daughter of the King of Bohemia, Ottokar I (+1230). Dagmar was married in 1205 to Valdemar II the Victorious, the King of Denmark. The cross - today exhibited at the National Museum in Copenhagen - is undoubtedly a Byzantine work. Most probably, it was made in the first half of the 12th century. It is so- called enkolpion, i.e. the hanging cross (gr. Έγϰόλπιου, on the chest). Both its sides are decorated with figurative scenes. The crucifixion of the Christ is depicted on one side. The Great Deēsis with St. Basil the Great and St. John Chrysostom is shown on the other side. There is a hollow in the body of the cross, in which a relic was deposited - most likely a particle of the wood of the True Cross. Although the Queen Dagmar's Cross is considered a national treasure in Denmark, only a little attention has been paid to it so far. It is almost unknown to the Czech researchers (it is briefly mentioned by J. E. Wocel, A. B. Černý, J. Květ, K. Chytil and most recently P. Balcárek). Regrettably, the most of researchers only...

Cette thèse vise à explorer les banquets en Norvège et en Islande aux XIIe et XIIIe siècles. Le sujet de cette étude, évoqué de manière éparse par l’historiographie, a pour objectif cardinal de de contrer cette lacune en fournissant un portrait global des festins à l’époque concernée. L’approche empruntée accorde une importance particulière aux rares descriptions de banquets ainsi qu’aux détails exceptionnels contenus dans les sources historiques. Cette enquête ambitionne également d’identifier et de comprendre les divers rôles joués par les réunions festives en Norvège et en Islande selon deux axes principaux. Le premier est celui de la convivialité, de la sociabilité, faisant un usage positif de ces rassemblements. Inversement, le second voyait l’instrumentalisation du festin comme appareil de distinction sociale et d’une affirmation agressive du rang de chaque convive. Cette approche permet de formuler une ébauche de catégorisation des banquets, de leur usage et de leur richesse. De plus, l’analyse offre l’occasion de constater les dimensions uniques de ce phénomène culturel prévalent de la Scandinavie de l’Ouest, mais également d’observer les similitudes entretenues avec le reste de l’Europe. Enfin, le dernier aspect abordé dans cette thèse vise à examiner en surface la translation de coutumes festives et courtoises d’un espace à un autre en fonction des relations politiques entre la Norvège et l’Islande. Pour y arriver, nous recourrons à des textes législatifs issus des deux régions à l’étude, de sagas royales, de sagas de contemporains et de documents produits dans l’environnement de la cour norvégienne. / This thesis explores feasting in Norway and Iceland during the 12th and 13th centuries. The subject of this work, often only merely mentioned by historiography, aims to fill this need by painting a general picture of banquets during the chosen time period. We aim to specifically address the topic by garnering exceptional details present in historical documents. This study also wishes to establish the various roles played by banquets by following two main axes. The first one sees the feast serving as a conveyer of social cohesion and friendships and also as a building tool for relationships. Inversely, the second exposes how feasts could serve more hostile purposes, notably distinguishing every attendee and underlining social inequalities among a given group. We also aim to categorize feasts, to identify their uses and their breadth. Through these efforts, we also identify unique traits that define this practice around western Scandinavia, but also the differences it entertains against other European regions. Finally, this study aims to touch on the transmission of customs surrounding feasting from Norway to Iceland incidental to increasing political relationships. To achieve the aforementioned goals, we solicited the use legal texts from both regions, king sagas, contemporary sagas, as well as documents coming from the Norwegian court.

The thesis is divided into three sections. The first section discusses the manuscript Marcianus graecus 524, the second looks at the Greek text of the dedicatory epigrams on works of art from the same manuscript, and the third puts these texts in their context. In the first part, the compilation of the manuscript is analysed. I suggest that the manuscript was copied mainly by one individual scribe living in Constantinople at the end of the thirteenth century. He copied the quires individually, but at some point he put all these quires together, added new quires, and compiled an anthology of poetry. The scribe’s connection to the Planudean School and the Petra monastery in Constantinople is discussed. Although their relationship remains inconclusive, the manuscript provides evidence regarding the literary interests of late-thirteenth-century intellectuals. The second part contains thirty-five unpublished dedicatory epigrams on works of art. New readings are offered for the text of previously published epigrams. The third section analyses the dedicatory epigrams on works of art in their context. The first chapter of this section discusses the epigrams as Gebrauchstexte, i.e. texts with a practical use. The difference between epigrams intended to be inscribed and epigrams intended to be performed is highlighted. In the next chapter of this part, La poésie de l’objet, the composition of the dedicatory epigrams is discussed. The conventional character of the epigrams suggests that the poetics express the ritual aspect of the epigram. The last chapter considers the texts from a more pragmatic angle. After a short discussion of the objects on which the epigrams were written, the mechanisms of the twelfth-century art market are presented based on evidence taken mainly from the epigrams. At the end of this part, conclusions are drawn on the understanding of these texts in the twelfth century.

Version remaniée : Thèse de doctorat : Lettres : Rennes 2 : 1989. / Contient le texte de diverses versions du conte. Bibliogr. p. 317-339. Index.