Faced with the growing complexity of application scenarios for autonomous robots, context-awareness and adaptivity are becoming more and more essential abilities to determine environmental circumstances and to adapt to them accordingly. While semantic technologies are widely used for the modelling of a robot's context, purposive robot behaviour is typically described using plan or plan execution languages which lack explicit semantics for context representations. Context-sensitive adaptive behaviour emerges from the whole transformation process though, from context-awareness to the subsequent execution of associated plans. This comprehensive view of adaptivity lacks sufficient treatment in the field of robotics. Addressing this issue, we have augmented the expressive plan execution language PLEXIL, allowing complex context expressions as Description Logic queries to form an integral part of constructs that define sophisticated behavioural reactions. To demonstrate the symbiosis of context-awareness and plan execution, the enhanced language PLEXIL-DL is employed in the avionics system for a reconnaissance mission of an Unmanned Air Vehicle.

Faced with the growing complexity of application scenarios social robots are involved with, the perception of environmental circumstances and the sentient reactions are becoming more and more important abilities. Rather than regarding both abilities in isolation, the entire transformation process, from context-awareness to purposive behaviour, forms a robot’s adaptivity. While attaining context-awareness has received much attention in literature so far, translating it into appropriate actions still lacks a comprehensive approach. In this paper, we present PLEXIL-DL, an expressive language allowing complex context expressions as an integral part of constructs that define sophisticated behavioural reactions. Our approach extends NASA’s PLEXIL language by Description Logic queries, both in syntax and formal semantics. A prototypical implementation of a PLEXIL-DL interpreter shows the basic mechanisms facilitating the robot’s adaptivity through context-awareness.

Today’s mission software requires ever more sophistication, being faced with the challenges of conducting Nnetwork-centric Operations (NCO) and exhibiting mission autonomy. Addressing these challenges, together with improving the engineering process in general, is the main output of the project described in this paper, accomplished at EADS Military Air Systems. The project comprises an architectural concept, a methodology, a development environment, a runtime environment and a simulation connector. The adequacy of the approach was demonstrated by means of a prototypical implementation of a NCO scenario.

Using middleware technologies in modern distributed embedded environments, one is often faced with connecting incompatible transport media to the communication stack, especially in the military domain. In case of CORBA, natively unsupported media can be plugged in via ESIOP, integrating it into the middleware. This approach tightly couples media to middleware and tends to be unportable between middleware technologies. In contrast, this paper suggests transport abstraction by providing IPv6 adapters for each medium, exploiting the predominance of IP support in middleware and existing adapters. Apart from the flexibility gained compared to transport integration, the proof-of-concept implementations of both approaches, based on CORBA and CAN, show an up to a tenfold improvement in invocation time over integration. Transport abstraction not only reduces the problem to adapting media to IPv6, but also allows transport media independent substitution of middleware and vice versa.

Network-centricity and autonomy are two buzzwords that have found increasing attention since the beginning of this decade in both, the military and civil domain. Although various conceptions exist of which capabilities are required for a system to be considered network-centric or autonomous, there can hardly be found proposals or prototypes that describe concrete transformations for both capabilities into software. The presented paper reviews work accomplished at EADS Military Air Systems driven by the need to develop an infrastructure that supports the realisation of both concepts in software with respect to traditional and modem software engineering principles, e.g., re-use and service-oriented development. This infrastructure is provided in form of a prototypical framework, accompanied by configuration and monitoring tools. Tests in a complex scenario requiring network-centricity and autonomy have shown that a significant technical readiness level can be reached by using the framework for mission software development.

This paper presents a dense time extension of the π-calculus based on time consuming transition semantics. The proposed extension tries to minimise the changes to the standard calculus whilst gaining enough expressiveness to model real-time systems. Syntactic rules and the operational semantics of the timed π-calculus are given. However, the main contribution consists of systems of equations recursively defined over timed labelled transition systems (TLTS), whose solutions provide time sets stating when processes and transitions are active.

A method is disclosed for molding a reflector of light-transmissive urethane, with a retroreflective pattern of a multiplicity of angled facets at the back surface of the reflector. In a mold cavity for the reflector there is provided a mold portion shaped to form the multiplicity of angled facets. Prior to filling of the mold, there is applied to the mold portion temporarily a transfer coating of a material which will maintain the angled facets reflective in a urethane reflector. A releasing agent is applied to the remainder of the mold other than the subject mold portion, then the mold is filled with urethane material. Once the urethane material has set, the mold is opened and the molded urethane is stripped off the special mold portion, leaving the transfer coating, which acts as a release coating, adhered to the angled facets.

This paper presents a formal specification methodologyfor embedded systems which is founded upon the p-calculus process algebra. The domain model underlying this newlydeveloped methodology identifies eight categories of system building blocks each of which describes a particular system facet. Based on these building blocks complex embeddedsystems can be specified, refined, and formally verified. The theories underlying both system specification and refinement are explained and exemplified by applications from the field of aeronautics.

Preliminary lateral force microscopy (LFM) results are presented which were obtained at different temperatures on thin films of poly(tetrafluoroethylene) prepared by friction deposition. Chain-chain distances of rodlike poly(tetrafluoroethylene) macromolecules were determined as a function of temperature from LFM images which exhibit molecular resolution. The value of the linear thermal expansion coefficient in the chain-perpendicular direction was estimated to be 3.5x10-3 [1/°C] in the temperature range between+10°C and+40°C. This value is higher than the literature data quoted for the temperature range between 0 °C and 25 °C. Possible reasons for this deviation are discussed.

Lateral force microscopy (LFM) studies of poly(tetrafluoroethylene) (PTFE) films with molecular resolution are reported. Thin PTFE layers with a high degree of orientation were obtained by pressing and sliding a block of polymer on a clean, heated muscovite mica substrate. LFM nanographs obtained on these films by scanning at directions between ca. 40 and 90° with respect to the film orientation direction, i.e. with respect to the direction of the polymer chains, showed a “stick-slip” type frictional motion of the LFM probe tip at the molecular level. The friction force observed at constant load decreased with decreasing scan angles. Chain-chain packing distances obtained by LFM and contact-mode atomic force microscopy were the same to within the experimental error and had a value of 5.8 Å. Dual-mode contact AFM/LFM imaging was also performed by scanning in the chain direction. Here LFM nanographs showed no distinct “stick-slip” phenomenon. The contact mode AFM images, however, exhibited clear molecular resolution with the expected chain-chain periodicity. The disappearance of the “stick” component in LFM scans performed in the chain direction was attributed to the smooth surface of PTFE on the molecular scale.

Lateral force microscopy (LFM) studies of poly(tetrafluoroethylene) (PTFE) films obtained by pressing and sliding a block of polymer on a clean heated glass surface are reported. The sample preparation process utilized, invented by Wittmann and Smith, resulted in samples of thin, well-oriented films and fibers of PTFE which were deposited on the glass. The formation of such oriented PTFE films was confirmed by dual LFM/AFM images. During LFM/AFM scanning, PTFE molecules were picked up by the nanoscope tip probe, which clearly reduced the frictional force differences measured between glass and PTFE. This observation is in line with the model of Tabor, which assumes strong interfacial tension between PTFE and glass during sliding friction. LFM experiments performed on the PTFE films at scan directions between ca. 40 and 90 degrees with respect to the polymer main chain orientation showed a ''stickslip'' type frictional motion at the molecular level. This phenomenon allowed us to obtain LFM images of a synthetic polymer with molecular resolution. Chain-chain packing distances obtained by LFM and contact-mode AFM were identical to within the experimental error and had a value of 5.78 Angstrom at 25-30 degrees C imaging temperature. Dual-mode contact AFM/LFM imaging was also performed by scanning in the chain direction. Here LFM nanographs showed no measurable ''stick-slip'' phenomenon; i.e., basically a featureless, flat image was obtained. The contact-mode AFM images, however, exhibited clear molecular resolution with the expected chain-chain periodicity. The disappearance of the ''stick'' component in scans performed in the chain direction is a result of the smooth surface of PTFE on the molecular scale.

This study investigated the release of nitric oxide (NO) from glyceryl trinitrate (GTN) and SIN-1 in Langendorff rabbit hearts. Infusion of either GTN (10-40 microM) or SIN-1 (0.45-4.5 microM) into the coronary inflow tract resulted in a decrease in coronary perfusion pressure and NO release (oxyhemoglobin technique) into the coronary effluent. NO release from SIN-1 occurred spontaneously whereas passage through the coronary circulation, i.e. active metabolism, was required for NO release from GTN. Removal of the coronary endothelium and blockade of endothelial NO formation did not affect NO release from GTN and SIN-1. In GTN-tolerant hearts, there was a considerable inhibition of GTN- but not SIN-1-induced NO formation and coronary vasodilation. These data suggest (1) that metabolic NO release from GTN occurs during passage of the coronary circulation and is independent of the presence of endothelium, and (2) reduced NO release is a major cause of nitrate tolerance.

We investigated the possible involvement of reduced nitric oxide (NO) formation in development of nitrate tolerance in an intact organ circulation. NO formation was measured spectrophotometrically on-line in the coronary effluent of Langendorff hearts of rabbits. Short-term (3 min) infusion of glyceryl trinitrate (GTN, 40 $mUM) or a sydnonimine (SIN-1, 2.3 $mUM), the active metabolite of molsidomine, into the coronary inflow tract resulted in a decrease in coronary vascular resistance and NO release into the coronary effluent. Pretreatment with 250 $mUM GTN for 30 min resulted in considerably reduced NO formation and coronary vasodilation, whereas NO release and coronary vasodilation subsequent to SIN-1 remained unchanged, In hearts pretreated with 250 $mUM SIN-1 for 30 min, there was no effect on GTN- or SIN-l–induced vasodilation and NO release. Studies of cyclic GMP formation in rat lung fibroblasts further indicated that GTN bioconversion rather than desensitization of the soluble guanylate cyclase in involved in GTN tolerance. These data suggest metabolic. endothelium-independent NO release from GTN during passage through the coronary circulation. This NO release is reduced in nitratetolerant cells and appears to be the major cause of nitrate tolerance in intact circulatory systems.

The release of NO from SIN-1, the active metabolite of molsidomine, was measured in vitro in Langendorff-perfused rabbit hearts. NO in the coronary effluent was determined on-line using the oxyhemoglobin technique. Left ventricular and coronary perfusion pressure were also recorded continuously. Glyceryl trinitrate and iloprost were used as reference compounds. Infusion of SIN-1 or glyceryl trinitrate into the coronary inflow resulted in a significant and dose-dependent NO release. An apparently identical response was seen when SIN-1 was infused into the coronary effluent while the response to glyceryl trinitrate was greatly reduced or abolished. The glyceryl trinitrate-induced coronary vasodilation was only slightly diminished in presence of oxyhemoglobin whereas the response to SIN-1 was abolished. This is explained by complete scavenging of NO by oxyhemoglobin within the vessel lumen. In isolated porcine aortic endothelial cells, SIN-1 induced a significant and dose-dependent increase in cyclic GMP, whereas glyceryl trinitrate was ineffective. This would argue against biotransformation of glyceryl trinitrate to NO by endothelial cells. Finally, glyceryl trinitrate-tolerant heart preparations exhibited a considerably reduced or even undetectable release of NO, whereas the response to SIN-1 was unchanged.