Multiplexed solutions to integrate the onboard electronics in the city-bus vehicles
The electrical circuits and installations in buses and coaches are essential for their good working. Drive, braking, suspension, opening door, security and communication systems depend on the electrical system of the vehicle. The disproportionate length of cable (about 4 Km of cables and 100 Kg of weight in a conventional installation), with more of 2,000 connections per vehicle, generates great difficult and the point-to-point links are not an effective solution. The industrial communication networks or fieldbuses are a multiplexed solution for onboard electronics in the public transport buses and coaches. The authors are working in the design and implementation of new modules based on FPGAs (Field Programmable Gate Arrays) to integrate body and chassis functions in the multiplexed solutions from manufacturers.
Design and Application of SAE J1939 Communication Database in City-Bus Information Integrated Control System Development
With the increase of the number and the complexity of city-bus ECUs (Electronic Control Units), point-to-point link method in traditional city-bus has caused the problems of information exchange, reliability and maintenance. In this paper, we defined the conception of CBIICS (City-Bus Information Integrated Control System) and constructed CBIICS framework with high speed CAN bus and low speed CAN bus so as to share information between different ECUs. In order to provide consistent control and status data in V mode-based CBIICS development process, we designed SAE J1939 communication database to implement ECU, message and signal management and query. According to the electrical devices of an actual city-bus, we finally designed and implemented city-bus lamp control experiment system based on SAE J1939 protocol.
Numerical tools applied to power reactor noise analysis
In order to be able to calculate the space- and frequency-dependent neutron noise in real inhomogeneous systems in two-group theory, a code was developed for the calculation of the Green's function (dynamic transfer function) of such systems. This paper reports on the development as well as the test and application of the numerical tools employed. The code that was developed yields the space-dependence of the fluctuations of the neutron flux induced by fluctuating properties of the medium in the two-group diffusion approximation and in a two-dimensional representation of heterogeneous systems, for both critical systems and non-critical systems with an external source. Some applications of these tools to power reactor noise analysis are then described, including the unfolding of the parameters of the noise source from the induced neutron noise, measured at a few discrete locations throughout the core. Other concrete applications concern the study of the space-dependence of the Decay Ratio in Boiling Water Reactors, the noise-based estimation of the Moderator Temperature Coefficient of reactivity in Pressurized Water Reactors, the modeling of the beam- and shell-mode core-barrel vibrations in Pressurized Water Reactors, and the investigation of the validity of the point-kinetic approximation in subcritical systems driven by an external source. In most of these applications, calculations performed using the code are compared with at-power plant measurements. Power reactor noise analysis applications of the above type, i.e. core monitoring without disturbing plant operation, is of particular interest in the framework of the extensive program of power uprates worldwide.