Simulation of transient flow in a shock tunnel and a high Mach number nozzle

A finite volume Navier-Stokes code was used to simulate the shock reflection and nozzle starting processes in an axisymmetric shock tube and a high Mach number nozzle. The simulated nozzle starting processes were found to match the classical quasi-1-D theory and some features of the experimental measurements. The shock reflection simulation illustrated a new mechanism for the driver gas contamination of the stagnated test gas

Mach 4 and Mach 8 axisymmetric nozzles for a shock tunnel

The performance of two axisymmetric nozzles which were designed to produce uniform, parallel flow with nominal Mach numbers of 4 and 8 is examined. A free-piston-driven shock tube was used to supply the nozzle with high-temperature, high-pressure test gas. The inviscid design procedure treated the nozzle expansion in two stages. Close to the nozzle throat, the nozzle wall was specified as conical and the gas flow was treated as a quasi-one-dimensional chemically-reacting flow. At the end of the conical expansion, the gas was assumed to be calorically perfect, and a contoured wall was designed (using method of characteristics) to convert the source flow into a uniform and parallel flow at the end of the nozzle. Performance was assessed by measuring Pitot pressures across the exit plane of the nozzles and, over the range of operating conditions examined, the nozzles produced satisfactory test flows. However, there were flow disturbances in the Mach 8 nozzle flow that persisted for significant times after flow initiation

Synchronisation of financial crises

This paper develops concordance indices for studying the simultaneous occurrence of financial crises. The indices are designed to cope with these typically low incidence events. This leads us to confine attention to non-tranquil periods to develop a bivariate index and its multivariate analog for potentially serially correlated categorical data. An application to the Bordo et al. (2001) data set reveals the extent of concordance in banking and currency crises across countries. The internationalisation of financial crises in the 20th century is shown to have increased for currency crises and decreased for banking crises

Simulation of Laminated Object Manufacturing (LOM) with Variation of Process Parameters

A previously developed and verified thermal model for Laminated Object Manufacturing (LOM) was used to investigate the effects of various processing parameters on the temperature profile in a LOM part during the build cycle. The mathematical model, based on 3-dimensional transient heat conduction in a rectangular geometry LOM part, allows calculation ofthe transient temperature distribution within the part during the application of a new layer as well as during other periods ofthe LOM build cycle. The parameters roller temperature, roller speed, chamber air temperature, base plate temperature, and laser cutting time were independently varied, and the LOM process response simulated. The results were analyzed in order to gain insight into potential strategies for intelligent process control.Mechanical Engineerin

MBCNS2 Example Book

MBCNS2 is a small collection of programs for the simulation of transient two-dimensional (or axisymmetric) flows. It is part of the larger collection of compressible flow simulation codes found at http://www.mech.uq.edu.au/cfcfd/. This manual is a collection of example simulations: scripts, results and commentary. It may be convenient for new users of the code to identify an example close to the situation that they wish to model and then adapt the scripts for that example

A tutorial guide to programming PIC18 microcontrollers with FlashForth

Modern microcontrollers provide an amazingly diverse selection of hardware peripher-als, all within a single chip. One needs to provide a small amount of supporting hardware to power the chip and connect its peripheral devices to the signals of interest and, when powered up, these devices need to be configured and monitored by a suitable firmware program. These notes focus on programming a PIC18F2520 microcontroller in a simple hardware environment and provide a number of example programs (in the Forth language) to illustrate the use of some of the MCU’s peripheral devices

The BCD transient recorder revisited: firmware for the ISA-to-USB bridging card and software for the graphical user interface

This report describes recent updates to the custom-built data-acquisition hardware operated by the Center for Hypersonics. In 2006, an ISA-to-USB bridging card was developed as part of Luke Hillyard's final-year thesis. This card allows the hardware to be connected to any recent personal computers via a (USB or RS232) serial port and it provides a number of simple text-based commands for control of the hardware. A graphical user interface program was also updated to help the experimenter manage the data acquisition functions. Sampled data is stored in text files that have been compressed with the gzip for mat. To simplify the later archiving or transport of the data, all files specific to a shot are stored in a single directory. This includes a text file for the run description, the signal configuration file and the individual sampled-data files, one for each signal that was recorded