Search results

Filters

  • Journals
  • Authors
  • Keywords
  • Date
  • Type

Search results

Number of results: 74
items per page: 25 50 75
Sort by:

Abstract

Fourteen symposia on early/lower vertebrates have taken place over the last 50 years, usually at about four year intervals. An average 60 participants have taken part at these symposia, with over one hundred occasionally. The results of the symposia have been published in proceedings. The symposia started honoring E. A:son Stensiö and E. Jarvik. Honors were taken up at the 11th symposium in Uppsala again. Since the 13th symposium a Stensiö award is also given to young researchers in the field.
Go to article

Abstract

In contemporary high-pressure die casting foundries, the mastery of each sequence in the production cycle is more and more important. In the paper, an example of virtual analysis of gearbox casting from Al alloy will be presented. It includes a large variety of parameters, as follows: choosing of appropriate foundry technology, calculation of computer simulation of casting process which takes into account the filling process of cold chamber and filling of cavity, model description of three phases in high-pressure die casting, flow of molten metal, solidification, formation of stress and deformations. Additionally, the optimization of cooling and heating systems will be compared with calculated volume defects, dimensions of castings and their deformations with experimentally obtained values.
Go to article

Abstract

The Puck (Mrzezino) hoard and procedures of the Prussian Monarchy towards coin finds. Treasure legislation in the Prussian monarchy shared hoards between the finders and the owners of the ground. This regulation produced archival evidence dating back to the eighteenth century. The large gold hoard, found in what is nowadays Mrzezino in northern Poland in 1795, was reported to Berlin shortly after its discovery. In the beginning, mainly juridical questions were discussed, but in 1798, this moved to the discussion of what to do with the coins and where and to whom they should be sold. The archival reports reveal that the coins were mainly of Anastasius, some of Zeno’s and only a few of Leo, Basiliscus and Theodosius and, as their value was above intrinsic value, they were sold to the royal collection in Berlin as well as to collections in Prussia and Poland.
Go to article

Abstract

This article traces the process by which Ricoeur establishes the character of the discipline of history as a form of narration which expresses the relation between the experience of ‘belonging-to-history’ and the capacity to place this experience at a distance and, thereby, to experience it reflectively.
Go to article

Abstract

A research study aimed at developing a novel indoor positioning system is presented. The realized system prototype uses sensor fusion techniques to combine information from two sources: an in-house developed local Ultra-Wideband (UWB) radio-based ranging system and an inertial navigation system (INS). The UWB system measures the distance between two transceivers by recording the round-trip-time (RTT) of UWB radio pulses. Its principle of operation is briefly described, together with the main design features. Furthermore, the main characteristics of the INS and of the Extended Kalman Filter information fusion approach are presented. Finally, selected static and dynamic test scenario experimental results are provided. In particular, the advantages of the proposed information fusion approach are further investigated by means of a high dynamic test scenario.
Go to article

Abstract

This paper presents and compares microphone calibration methods for the simultaneous calibration of small electret microphones in a wave guide. The microphones are simultaneously calibrated to a reference microphone both in amplitude and phase. The calibration procedure is formulated on the basis of the damped plane wave propagation equation, from which the acoustics field along the wave guide is predicted, using several reference measurements. Different calibration models are presented and the methods were found to be sensitive to the formulation, as well as to the number of free parameters used during the reconstruction of the wave-field. The wave guide model based on five free parameters was found to be the preferred method for this type of calibration procedure.
Go to article

Abstract

Drinking fresh water, turning the lights on, travelling by tram, calling our family, or getting a medical treatment are usual activities, but the underlying SCADA (Supervisory Control and Data Acquisition) systems like CIS (Critical Infrastructure Systems), ICS (Industrial Control Systems) or DCS (Distributed Control Systems) were always the target of many types of attacks, endangered the above mentioned simple activities. During the last decades because of the fast spread of the internet based services and the continuous technical development these systems become more vulnerable than ever. Full reconstruction and innovative changes in older SCADA systems has high cost, and it is not always rewarding. Communication protocols as Modbus (1979) serve as a main basis for SCADA systems, so security of Modbus has a major impact of the security of SCADA systems. Our paper raises and answers questions about the security of the Modbus RTU protocol. We focus on the serial Modbus protocol, because in that method we found many unsolved problems, like lack of authentication of the participants, lack of secure channel and so on. The aim of this paper to propose a secure communication alternative for Modbus RTU @ RS485 wire. The main advantage of the proposed method is the coexistence with traditional slaves and bus systems and only software update is necessary
Go to article

This page uses 'cookies'. Learn more