Search results for: Ramses van der Toorn

Authors: Robert Setekera, Ramses van der Toorn

Abstract:

We present an extensive analysis of the temperature dependence of the local avalanche model used in most of the modern compact models for bipolar transistors. This local avalanche model uses the Chynoweth's empirical law for ionization coefficient to define the generation of the avalanche current in terms of the local electric field. We carry out the model analysis using DC-measurements taken on both Si and advanced SiGe bipolar transistors. For the advanced industrial SiGe-HBTs, we consider both high-speed and high-power devices (both NPN and PNP transistors). The limitations of the local avalanche model in modeling the temperature dependence of the avalanche current mostly in the weak avalanche region are demonstrated. In addition, the model avalanche parameters are analyzed to see if they are in agreement with semiconductor device physics.

Keywords: avalanche multiplication, avalanche current, bipolar transistors, compact modeling, electric field, impact ionization, local avalanche

Procedia PDF Downloads 595

Authors: Hassan Mohmed, Mohamed Ismail, Aiman Rezk

Abstract:

Introduction: This project aims to document and preserve decorated wooden coffins which were discovered in Luxor by Egyptian mission at Luxor, (SR Numbers:2514,2519,2520,2521,5469).These decorated wooden coffins dates back to Egyptian New Kingdom period and has been transferred to the Cairo Museum, to be displayed at the museum. These decorated wooden coffins discovered in the cache-tomb of Bab el-gasus at Deir el-Bahari, Luxor. This site has been dictated for the burials of priests of Amun through 18th Dynasty the coffins owners held these titles, which are as follows: "the embalmer of the beautiful-house (the place of embalming)" and "the servant in the place of truth". Methodology: Methodology: The project objectives making such decorated wooden coffins more visible to visitors through the use of 3D reconstructed coffins and high resolution photos which describe the history of using the wooden coffins during the Ancient Egyptian history Especially, The Cairo Museum is going to exhibit decorated wooden coffins in New kingdom. The project goals is to document decorated wooden coffins and arrange an exhibition, where such decorated wooden coffins going to be displayed next to the Ramses 2nd coffin, This research focuses on the text analyses and the technology. Paleographic information found on these objects. Conclusion: The project shows the importance of using coffins in Ancient Egypt, and connecting their usage through Ancient Egyptian periods; the coffins had a unique Symbolized in ancient Egypt and connect the public with their kings. The Egyptian put coffins in their tombs that they hope to save their bodies’ afterlife. This research will be beneficial and useful for the heritage and ancient civilizations, Indeed this study will open a destination in order to know how to identify these collections and how to exhibit them commensurate with the natural of the ancient Egyptian history and heritage.

Keywords: archaeology, decorated wooden coffins, 3D digital tools for heritage management, museums

Procedia PDF Downloads 49

Authors: Jérôme de Reffye, Marc Antoni

Abstract:

Following the development of the ERTMS system, we think it is interesting to develop another software-based track circuit system which would fit secondary railway lines with an easy-to-work implementation and a low sensitivity to rail-wheel impedance variations. We called this track circuit 'Track Railway by Automatic Circuits.' To be internationally implemented, this system must not have any mechanical component and must be compatible with existing track circuit systems. For example, the system is independent from the French 'Joints Isolants Collés' that isolate track sections from one another, and it is equally independent from component used in Germany called 'Counting Axles,' in French 'compteur d’essieux.' This track circuit is fully interoperable. Such universality is obtained by replacing the train detection mechanical system with a space-time filtering of train position. The various track sections are defined by the frequency of a continuous signal. The set of frequencies related to the track sections is a set of orthogonal functions in a Hilbert Space. Thus the failure probability of track sections separation is precisely calculated on the basis of signal-to-noise ratio. SNR is a function of the level of traction current conducted by rails. This is the reason why we developed a very powerful algorithm to reject noise and jamming to obtain an SNR compatible with the precision required for the track circuit and SIL 4 level. The SIL 4 level is thus reachable by an adjustment of the set of orthogonal functions. Our major contributions to railway engineering signalling science are i) Train space localization is precisely defined by a calibration system. The operation bypasses the GSM-R radio system of the ERTMS system. Moreover, the track circuit is naturally protected against radio-type jammers. After the calibration operation, the track circuit is autonomous. ii) A mathematical topology adapted to train space localization by following the train through a linear time filtering of the received signal. Track sections are numerically defined and can be modified with a software update. The system was numerically simulated, and results were beyond our expectations. We achieved a precision of one meter. Rail-ground and rail-wheel impedance sensitivity analysis gave excellent results. Results are now complete and ready to be published. This work was initialised as a research project of the French Railways developed by the Pi-Ramses Company under SNCF contract and required five years to obtain the results. This track circuit is already at Level 3 of the ERTMS system, and it will be much cheaper to implement and to work. The traffic regulation is based on variable length track sections. As the traffic growths, the maximum speed is reduced, and the track section lengths are decreasing. It is possible if the elementary track section is correctly defined for the minimum speed and if every track section is able to emit with variable frequencies.

Keywords: track section, track circuits, space-time crossing, adaptive track section, automatic railway signalling

Procedia PDF Downloads 307