Wide area detection system: Conceptual design study

An integrated sensor for traffic surveillance on mainline sections of urban freeways is described. Applicable imaging and processor technology is surveyed and the functional requirements for the sensors and the conceptual design of the breadboard sensors are given. Parameters measured by the sensors include lane density, speed, and volume. The freeway image is also used for incident diagnosis

Design of a high-speed digital processing element for parallel simulation

A prototype of a custom designed computer to be used as a processing element in a multiprocessor based jet engine simulator is described. The purpose of the custom design was to give the computer the speed and versatility required to simulate a jet engine in real time. Real time simulations are needed for closed loop testing of digital electronic engine controls. The prototype computer has a microcycle time of 133 nanoseconds. This speed was achieved by: prefetching the next instruction while the current one is executing, transporting data using high speed data busses, and using state of the art components such as a very large scale integration (VLSI) multiplier. Included are discussions of processing element requirements, design philosophy, the architecture of the custom designed processing element, the comprehensive instruction set, the diagnostic support software, and the development status of the custom design

The dynamics of a long flexible horizontal circular cylinder in water waves.

SIGLEAvailable from British Library Document Supply Centre- DSC:D86427 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Soft-decision minimum-distance sequential decoding algorithm for convolutional codes

The maximum-likelihood decoding of convolutional codes has generally been considered impractical for other than relatively short constraint length codes, because of the exponential growth in complexity with increasing constraint length. The soft-decision minimum-distance decoding algorithm proposed in the paper approaches the performance of a maximum-likelihood decoder, and uses a sequential decoding approach to avoid an exponential growth in complexity. The algorithm also utilises the distance and structural properties of convolutional codes to considerably reduce the amount of searching needed to find the minimum soft-decision distance paths when a back-up search is required. This is done in two main ways. First, a small set of paths called permissible paths are utilised to search the whole of the subtree for the better path, instead of using all the paths within a given subtree. Secondly, the decoder identifies which subset of permissible paths should be utilised in a given search and which may be ignored. In this way many unnecessary path searches are completely eliminated. Because the decoding effort required by the algorithm is low, and the decoding processes are simple, the algorithm opens the possibility of building high-speed long constraint length convolutional decoders whose performance approaches that of the optimum maximum-likelihood decoder. The paper describes the algorithm and its theoretical basis, and gives examples of its operation. Also, results obtained from practical implementations of the algorithm using a high-speed microcomputer are presented

Dynamic analysis of the cutting forces in gear hobbing

The work reported in this thesis has been developed to predict and measure the cutting forces in the gear hobbing process. A review of past research in this area has highlighted the need to adopt a different approach to modelling the process in order to predict the cutting forces. The hobbing process has been described using six different co-ordinate systems and the kinematic relationships between these systems established. A single rack profile has been used to represent the profile of a single cutting tooth from the hob which was then extended to simulate the hob itself. When the hob gashes pass through the cutting region surfaces are generated which, if mapped on a regular grid can give the basis to estimate the depth of cut, i.e. the instantaneous chip thickness produced by that particular tooth. The instantaneous cutting forces generated by that tooth then can be estimated by using the concept of a specific cutting force of the workpiece material. The estimation of cutting forces acting on a single tooth space was used to predict the cutting forces produced during machining of a full gear, by assuming that the forces acting in a particular tooth space are equal to those acting on the adjacent tooth space at an equivalent instant in the cutting cycle. In order to validate predicted results, a Churchill PH1612 hobbing machine was retrofitted with a CNC control system at Newcastle University, utilising a programmable multi axis controller (PMAC). A specially made single toothed gear, and a full gear were machined, and cut on this machine, and the cutting forces measured in real time using a 3-axis dynamometer. The force signals produced by the dynamometer were measured utilising a 12-bit ADC card. Code, written in C, was developed to perform the many functions needed for the overall control of the machine, but additionally was used to capture both the cutting forces and axis position data. The results of the simulation and modelling have shown very good agreement with those obtained experimentally.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Stepping from Graph Transformation Units to Model Transformation Units

Graph transformation units are rule-based entities that allow to transform source graphs into target graphs via sets of graph transformation rules according to a control condition. The graphs and rules are taken from an underlying graph transformation approach. Graph transformation units specify model transformations whenever the transformed graphs represent models. This paper is based on the observation that in general models are not always suitably represented as single graphs, but they may be specified as the composition of a variety of different formal structures such as sets, tuples, graphs, etc., which should be transformed by compositions of different types of rules and operations instead of single graph transformation rules. Consequently, in this paper, graph transformation units are generalized to model transformation units that allow to transform such kind of composed models in a rule-based and controlled way. Moreover, two compositions of model transformation units are presented