Performance and optimization of a derated ion thruster for auxiliary propulsion

The characteristics and implications of use of a derated ion thruster for north-south stationkeeping (NSSK) propulsion are discussed. A derated thruster is a 30 cm diameter primary propulsion ion thruster operated at highly throttled conditions appropriate to NSSK functions. The performance characteristics of a 30 cm ion thruster are presented, emphasizing throttled operation at low specific impulse and high thrust-to-power ratio. Performance data and component erosion are compared to other NSSK ion thrusters. Operations benefits derived from the performance advantages of the derated approach are examined assuming an INTELSAt 7-type spacecraft. Minimum ground test facility pumping capabilities required to maintain facility enhanced accelerator grid erosion at acceptable levels in a lifetest are quantified as a function of thruster operating condition. Approaches to reducing the derated thruster mass and volume are also discussed

Avoiding Latch Formation in Regular Expression Recognizers

Specialized silicon compilers, or module generators, are promising tools for automating the design of custom VLSI chips. In particular, generators for regular language recognizers have many applications. A problem called latch formation that causes regular expression recognizers to be more complex than they would first appear is identified. if recognizers are constructed in the most straightforward way from certain regular expressions, they may contain extraneous latches that cause incorrect operation. After identifying the problem, the article presents a source-to-source transformation that converts regular expressions that cause latch formation into expressions that do not. This transformation allows regular expression recognizers to be simpler, smaller, and faster, thus adding to the advantages of specialized silicon compilers

Accelerating Homomorphic Encryption in the Cloud Environment through High-Level Synthesis and Reconfigurable Resources

The recent surge in cloud services is revolutionizing the way that data is stored and processed. Everyone with an internet connection, from large corporations to small companies and private individuals, now have access to cutting-edge processing power and vast amounts of data storage. This rise in cloud computing and storage, however, has brought with it a need for a new type of security. In order to have access to cloud services, users must allow the service provider to have full access to their private, unencrypted data. Users are required to trust the integrity of the service provider and the security of its data centers. The recent development of fully homomorphic encryption schemes can offer a solution to this dilemma. These algorithms allow encrypted data to be used in computations without ever stripping the data of the protection of encryption. Unfortunately, the demanding memory requirements and computational complexity of the proposed schemes has hindered their wide-scale use. Custom hardware accelerators for homomorphic encryption could be implemented on the increasing number of reconfigurable hardware resources in the cloud, but the long development time required for these processors would lead to high production costs. This research seeks to develop a strategy for faster development of homomorphic encryption hardware accelerators using the process of High-Level Synthesis. Insights from existing number theory software libraries and custom hardware accelerators are used to develop a scalable, proof-of-concept software implementation of Karatsuba modular polynomial multiplication. This implementation was designed to be used with High-Level Synthesis to accelerate the large modular polynomial multiplication operations required by homomorphic encryption. The accelerator generated from this implementation by the High-Level Synthesis tool Vivado HLS achieved significant speedup over the implementations available in the highly-optimized FLINT software library

Very Large Area/Volume Microwave ECR Plasma and Ion Source

The present invention is an apparatus and method for producing very large area and large volume plasmas. The invention utilizes electron cyclotron resonances in conjunction with permanent magnets to produce dense, uniform plasmas for long life ion thruster applications or for plasma processing applications such as etching, deposition, ion milling and ion implantation. The large area source is at least five times larger than the 12-inch wafers being processed to date. Its rectangular shape makes it easier to accommodate to materials processing than sources that are circular in shape. The source itself represents the largest ECR ion source built to date. It is electrodeless and does not utilize electromagnets to generate the ECR magnetic circuit, nor does it make use of windows

Pharmacologic and Bacteriologic Properties of SCH‐27899 (Ziracin), an Investigational Antibiotic from the Everninomicin Family

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/90360/1/phco.19.15.1111.30576.pd

Miss Manners: A Specialized Silicon Compiler for Synchronizers

Miss Manners is a synchronizer generator that will produce the layout of a synchronizer given a high-level description. A synchronizer generator is a type of specialized silicon compiler. Synchronizer generators can greatly aid the design of systems that are structured as loosely-coupled networks of autonomous subsystems. Chips that are structured in this way have reduced communication requirements and greater tolerance for transient failures. We describe a language for specifying synchronization requirements and a compiler for translating the language into circuits that enforce the specifications

Some Student Perceptions of Grades Received on Speeches

Frequent evaluation of student work is standard practice in basic courses. Frequent evaluation assumes a relationship between the evaluation and improved performance. In higher education, evaluations are often expressed as grades. This study examines the relationship between twelve grades students receive on their speeches, and the affective and motivational effects those grades might have. Generally, the study found that students prefer higher grades but are motivated by lower grades. Specifically, the study indicates disparity between instructor intention in using pluses and minuses with grades and student reaction to the pluses and minuses