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Chemistry, Biochemistry

The third part of this work describes a simple laboratory experiment for junior high or high school students that promotes understanding of photolithography, crosslinking density, and the process of photopolymerization, while demonstrating the power of rapid prototyping used to fabricate microscale devices. The versatility of photolithography for microchip construction is exemplified by allowing each student to fabricate polymers in virtually any shape imaginable, including his or her silhouette.

Engineering, Electronics and Electrical and Computer Science

The current design process for workstation systems is over-taxed due to the size and diversity of realistic workload models. This thesis advocates a method to improve the design process by synthesizing prototype architectures from workloads. Focus is placed on the processor and memory systems, although the overall philosophy is applicable to other workstation components as well. Prototyping of memory systems is performed using methods to evaluate multiple designs with one pass over the address trace. Statistical sampling of address traces is adapted from traditional cache simulation to improve the performance and trace-size range of the techniques. These methods are extended to account for performance penalties due to multiprogramming. Prototyping of superscalar processors is performed using new statistical sampling techniques in conjunction with two simulation algorithms. The resource usage in an unlimited-resource simulation is used to select processor resource needs, but is only applicable to fixed operation latencies. A more general solution based on simulated annealing is developed and demonstrated as a prototyping method. The interaction between prototypes is investigated via simulation of three common schemes for coupling the processor to the memory system: blocking on a cache miss, limited-blocking, and non-blocking. It is concluded that sufficient design options exist to justify the separate design of the processor and the memory.

Engineering, Materials Science

Chapter 1 outlines the background and motivation for applying selective film deposition and soft-lithographic patterning techniques to microelectronic device fabrication. Chapter 2 describes how microcontact printing of organic self-assembled monolayers (SAMs) can be used to induce selective chemical vapor deposition (CVD) of platinum and palladium metal films on silicon, which are used extensively in the microelectronics industry to make metal silicide interconnects. The fabrication of platinum silicide Schottky diodes described in chapter 3 demonstrates the efficacy of soft-lithographically molded polymer templates for the selective deposition of platinum by CVD and the use of this same polymer template as a resist to buffered HF/NH4F oxide etchant. The silicon metal-oxide-semiconductor field effect transistor (MOSFET) fabrication detailed in chapter 4 demonstrates the successful use of soft-lithographic surface patterning in the fabrication of silicon devices requiring multilevel pattern registration. The fabrication of hydrogenated amorphous silicon thin-film transistors (TFrs) described in chapter 5 demonstrates the use of soft-lithography to pattern micron-scale device features on a spherically curved substrate---a significant advantage over conventional photolithography. Each of the three device arrays described in chapters 3, 4, and 5 was fabricated by a rapid prototyping process that uses mask patterns printed on transparency sheets rather than electron-beam written chrome-on-quartz masks. Finally, the investigation recorded in chapter 6 demonstrated how perfluoropolyethers (PFPEs) can be used as contact printing inks to make patterns of discrete beads with micron-scale lateral dimensions and nanoscale vertical dimensions. Such patterns may be useful as nanoscale spacers to prevent contact between patterned substrates in multi-substrate vertical assemblies.

Computer Science

In the past decades, the use of massively parallel supercomputers and distributed systems has increased, while the cost of computational resources has decreased steadily. This has lead to the emergence of a new dominant cost---that of the human developer. The solution of large-scale scientific problems has generated a need for development environments that ensure good human efficiency in the development of an application, in addition to the application's computational efficiency. We have developed an environment for rapid-prototyping of scientific codes, combining the ease-of-use of a MATLAB-like interactive interface with the high performance of a massively parallel system. This new approach to high-performance computing bridges the gap between high-level interactive interfaces and parallel architectures. It further allows the utilization of highly optimized parallel numerical libraries. Finally, the difficult and error-prone management of distributed resources is handled in a manner transparent to the user.

Health Sciences, Medicine and Surgery

Sintering of gel-cast calcium hydroxyapatite was studied by means of thermal analysis, XRD, mechanical testing, and SEM, both for sub-micron and the agglomerated powder type. Transformation temperatures of tri-calcium phosphate upon cooling were determined as 1475°C for (alpha' to alpha, 1190°C for alpha to beta, and 800--700°C range for beta to hydroxy-oxyapatite transformation. Dilatometry revealed that dimensional change reaches to saturation at 1200°C. Mechanical testing of the parts sintered at 1200--1500°C revealed that compressive strength in the 2--10 MPa range was achieved.

Computer Science

Prolog has a number of advantages for use in rapid prototyping. The explotation of parallelism holds the promise of making these prototypes directly executable. This dissertation addresses the parallel execution of Prolog programs without restricting the language to a pure subset or requiring user annotations. We begin by presenting methods for the OR parallel execution of Prolog programs with side effects such as assert, retract, and cut. Our methods have been implemented in an interpreter on the Alliant FX/8 and some results are presented. The second portion describes a method for estimating the inherent parallelism in Prolog programs. This work is based on the critical path methods of Kumar and is used to measure the best possible speedups under OR and AND/OR parallel models. The results of timing the Berkeley Benchmarks with these methods are presented. The last portion of the dissertation describes a method for applying Fortran techniques to Prolog programs. It begins by describing the construction of control flow graphs and shows how to identify recursive procedures that can be converted to loops. Lastly, dependence analysis methods and several source-to-source transformations from Fortran are used to synchronize and parallelize these loops. The results of hand-applying these transformations to a number of programs are presented. We demonstrate that we are able to obtain significant speedups on a number of programs by applying our transformations.

Engineering, Electronics and Electrical

In this work I present my research towards the development of a portable LOC system for medical diagnostics. A modular microfluidic LOC architecture is presented along with its implementation in two successive generations of devices. The architecture allows for rapid prototyping and simple design changes at low cost. Next, the design, fabrication, and characterization of a latchable microvalve is presented. Such a valve would be quite useful in a portable LOC for fluid storage and low power operation. Finally, I present my work towards realizing a portable instrument that interfaces directly with an LOC to create a simplified user interface. The goal of this research is to take microfluidic LOC technology to the next level where it can move out of the engineering lab and into the hands of the ultimate users (i.e., doctors, biologists, chemists).

Computer Science

The Vienna Development Method (VDM) supports the top-down development of software specified in a notation suitable for formal verification. VDM has been used in industrial applications to enhance the development process. In such environments VDM is applied in an informal, non-automated manner; verification conditions are generated and certified without the aid of specialized tools, and data types may not be formally axiomatized. This dissertation is based on the thesis that the time is ripe for the construction of environments which partially automate development methods similar to VDM, and that such environments will prove useful in industrial settings. ENCOMPASS is an automated environment which supports a formal development method similar to VDM; it supports rapid prototyping and program verification, as well as providing simple facilities for configuration control and project management. In ENCOMPASS, components are specified using a combination of natural language and PLEASE, a wide-spectrum executable specification and design language. PLEASE specifications may be used in proofs of correctness; they may also be automatically transformed into prototypes which use Prolog to "execute" pre- and post-conditions. In ENCOMPASS, PLEASE specifications are incrementally refined into Ada$\sp1$ implementations. Each refinement is verified before another is applied; therefore, the final components produced by the development satisfy the original specifications. In ENCOMPASS, the correctness of a refinement step can be verified using either testing, proof or peer review techniques. ENCOMPASS is an environment for the rigorous development of programs. Although detailed mechanical proofs are not required at every step, the framework is present so that they can be constructed if necessary. Proof techniques may be used which range from a very detailed, completely formal proof using mechanical theorem proving, to a development "annotated" with unproven verification conditions. Parts of a project may use detailed mechanical verification while other, less critical parts may be handled using less expensive techniques. We believe the use of future environments similar to ENCOMPASS will enhance the software development process. ftn$\sp1$Ada is a trademark of the U.S. Government, Ada Joint Program Office.

Engineering, Mechanical

The benefits of the above methodology to a MIMO powertrain system include a simplified mechanical structure, model-based control coordination, economical prototyping, as well as improved performance, efficiency, and ease of operation. An immediate application of these results to the earthmoving industry can reduce the cost of the control design cycle by formalizing the procedure. Simultaneously, a superior overall system will result by taking advantage of the multivariable structure.