Simplifying Embedded System Development Through Whole-Program Compilers

As embedded systems embrace ever more complicated microcontrollers, they present both new capability and new complexity. To simplify their development, some lessons of computer application development will translate with additional work. This thesis offers one such translation. It shows how whole-program compilers - those that broadly analyze a program\u27s entire source code - can achieve performance gains and remove faults in embedded system applications. In so doing, this yields a novel stackless threading system named UnStacked C. UnStacked C enables cooperative multithreading without the risk of stack overflows in embedded system applications. We also propose a novel preemption system called Lazy Preemption. Unstacked C with Lazy Preemption enables stackless preemptive multithreading in embedded systems. These remove the possibility of thread stack overflows, but also significantly reduces the memory required for multithreading in embedded system

The design, manufacture and analysis of a new implant for fracture fixation in human and veterinary orthopaedic surgery: the bone fastenerod

Fracture fixation in humans and animals has troubled surgeons and scientists since first it was attempted right up to the present day. At every milestone of achievement in the understanding and practice of fracture repair there has remained a significant problem left unresolved. Of paramount concern is the preservation of blood vessels and soft tissues, avoidance of stress shielding and concentration, promotion. of bone healing and a rapid return to function. However, matching these principles with the variables of degree and site of fracture/injury, age, size and status of patient, environmental and surgical factors is complex and difficult. To be able to attempt to allow a surgeon to make decisions about every case, knowing that the implant choice does not constrain him but offers flexibility to aim for the ideal fixation for each case, the system must be modular. The objectives were to produce an implant system that would satisfy the most up to date principles of fracture repair through design optimization, mechanical evaluation and testing for specific fracture types. The design was called the bone fastenerod following the optimization and analysis procedures to indicate the origins of its basic formation. To begin with, the design of the fastenerod had to be optimized and this was achieved using bench testing, initially of selected designs followed by finite element analysis, which allowed a greater number of designs to be processed. Once the optimum design had been found the process of manufacture had to be selected and various possible methods of manufacture were examined until the one most suitable was determined. To analyze the fastenerod, the current industry standard implants that are used in the same clinical type settings were chosen for comparative testing. Testing was performed using static and cyclic loading to failure with wood samples in four point, tensile, side, axial and torsional loading Specific fractures in dog, cat and horse bones were created and repaired using the fastenerod versus the best method currently available and tested in three point, tensile, axial, static loading to failure. Also, specific fractures were created in human mechanical bones and tested using axial, cyclic and four point bending again, comparing the fastenerod w ith the best technology available. The analysis revealed that in static loading the fastenerod was comparable to the industry standards for small implants but not comparable with the large human implants in the specific cases selected However, in the case of the cyclic loading to Mure , the fastenerod performed better than the plate system of similar size, with the ultimate load to failure being higher and no stress concentration leading to implant fracture or failure. Thus, the modular system of the bone fastenerod could now claim to provide fixation that could be flexible, less invasive and destructive to tissues, capable o f greater choice o f screw placement and stiff to level of choice whilst avoiding stress. concentration and shielding On the basis o f this analysis, the fastenerod system can proceed to fu ll c lin ica l trial

Problems in flotation

Little has been done to classify oils on the basis of their action as flotation agents, either for their frothing or their selective qualities...This investigation was undertaken chiefly to aid in effecting such a classification --page 3

Method of sampling diamond-drill core

The method of sampling and preparing samples of diamond-drill core, explained in this article, was used by the writer during a drilling campaign at Stirling, Cape Breton, Canada, in 1917 --page 4

Stackless Multi-Threading for Embedded Systems

Programming support for multi-threaded applications on embedded microcontroller platforms has attracted a considerable amount of research attention in the recent years. This paper is focused on this problem, and presents UnStacked C, a source-to-source transformation that can translate multithreaded programs written in C into stackless continuations. The transformation can support legacy code by not requiring any changes to application code; only the underlying threading library needs modifications. We describe the details of UnStacked C in the context of the TinyOS operating system for wireless sensor network applications. We present a modified implementation of the TOSThreads library for TinyOS, and show how existing applications programmed using TOSThreads can be automatically transformed to use stackless threads with only modifications in the build process. By eliminating the need to allocate individual thread stacks and by supporting lazy thread preemption, UnStacked C enables a considerable saving of memory used and power consumed, respectively

Stackless Multi-Threading for Embedded Systems

Programming support for multi-threaded applications on embedded microcontroller platforms has attracted a considerable amount of research attention in the recent years. This paper is focused on this problem, and presents UnStacked C, a source-to-source transformation that can translate multithreaded programs written in C into stackless continuations. The transformation can support legacy code by not requiring any changes to application code; only the underlying threading library needs modifications. We describe the details of UnStacked C in the context of the TinyOS operating system for wireless sensor network applications. We present a modified implementation of the TOSThreads library for TinyOS, and show how existing applications programmed using TOSThreads can be automatically transformed to use stackless threads with only modifications in the build process. By eliminating the need to allocate individual thread stacks and by supporting lazy thread preemption, UnStacked C enables a considerable saving of memory used and power consumed, respectively

An example of long-term variability for subsurface current and hydrographic patterns in the western North Atlantic

An example of long-term variability along 55W, perhaps interannual, for current and temperature distributions during mid-1975-1977 is presented. The existence of significant energy in the 55W data set at time scales longer than mesoscale (50-150 days) has been clear for , some time, but this is a first description of the latitudinal and vertical configuration of this low-frequency variability...