An experimental study was conducted to investigate the physics underlying the oscillation cycle of high Mach number, turbulent, open cavity flows. The specific aim was to investigate how the interaction between the cavity acoustics and the shear layer dynamics is affected by increasing Mach number. In the experiments the free-stream Mach numbers tested were 2 and 5, the cavity length-to-depth r...

The Mach micro kernel allows many operating system functions such as le systems, network protocols, TTY managers and process managers to be implemented as user level servers. Application programmers can write their own operating system servers suitable for their own applications. Mach, however, does not provide the mechanisms for building the servers which ensure predictable services. Therefore...

This paper describes the design, implementation, and use of a model of sporadic tasks in the Real-Time Mach kernel (MK83) [15]. The purpose of this exercise was two-fold. First, was our desire to provide a programming model in real-Time Mach (RT-Mach) that was better suited to the demands and requirements of applications that must execute in response to non-periodic, but repetitive events. Exam...

While the propagation and refraction of waves and shocks which constitute Mach cones have been well studied in continuous slowly varying stratified media such as gases, liquids, and solids, here we investigate these processes at the kinetic, discrete (or "molecular") level in a complex plasma where the stratification scale is of the order of the damping length. The shape of Mach cones formed by...

Two-alternative forced-choice procedures were used to measure the detectability of bright and dark bars at various locations across luminance patterns that produced Mach bands. Detection performance was significantly affected by both dark and bright Mach bands: poor detection performance was observed at locations near, but not in, the Mach bands; relatively good detection performance at locatio...

Mach; UNIX/OSF; HP-PA; virtually addressed cache architecture; PA-RISC; virtual memory Mach shares memory between tasks by virtual address aliasing. This means a physical page can be mapped to more than one virtual page at a time. This works well on hardware architectures that use a physically addressed cache, but can cause some problems for architectures that use a virtually addressed cache re...

From the analysis of a set of airborne images of ship wakes, we show that the wake angles decrease as U(-1) at large velocities, in a way similar to the Mach cone for supersonic airplanes. This previously unnoticed Mach-like regime is in contradiction with the celebrated Kelvin prediction of a constant angle of 19.47° independent of the ship's speed. We propose here a model, confirmed by numeri...

We describe the design and performance of code added to the Mach microkernel (Mach 4.0, version UK02p21) that permits one to build a Mach kernel that includes unmodiied Linux device drivers. We have written emulation code to support all Linux 1.3.35 network and SCSI drivers for the ISA and PCI I/O buses. Emulation increases latency, but very little. The degree depends on both device and operati...

The current CMU Mach 3.0 microkernel exports simple timestamp and delay abstractions through host get time() and a timeout parameter to mach msg(). While this is sufficient for many purposes, it does not provide the precision or generality required for a variety of realtime applications. In this paper we describe extensions to CMU’s Mach 3.0 which provide users with flexible time-based synchron...

We present numerical solutions of the steady and unsteady transonic small disturbance equations that describe the Mach reflection of weak shock waves. The solutions contain a complex structure consisting of a sequence of triple points and tiny supersonic patches directly behind the leading triple point, formed by the reflection of weak shocks and expansion waves between the sonic line and the M...