Air traffic control by distributed management in a MLS environment

The microwave landing system (MLS) is a technically feasible means for increasing runway capacity since it could support curved approaches to a short final. The shorter the final segment of the approach, the wider the variety of speed mixes possible so that theoretically, capacity would ultimately be limited by runway occupance time only. An experiment contrasted air traffic control in a MLS environment under a centralized form of management and under distributed management which was supported by a traffic situation display in each of the 3 piloted simulators. Objective flight data, verbal communication and subjective responses were recorded on 18 trial runs lasting about 20 minutes each. The results were in general agreement with previous distributed management research. In particular, distributed management permitted a smaller spread of intercrossing times and both pilots and controllers perceived distributed management as the more 'ideal' system in this task. It is concluded from this and previous research that distributed management offers a viable alternative to centralized management with definite potential for dealing with dense traffic in a safe, orderly and expeditious manner

Deceit: A flexible distributed file system

Deceit, a distributed file system (DFS) being developed at Cornell, focuses on flexible file semantics in relation to efficiency, scalability, and reliability. Deceit servers are interchangeable and collectively provide the illusion of a single, large server machine to any clients of the Deceit service. Non-volatile replicas of each file are stored on a subset of the file servers. The user is able to set parameters on a file to achieve different levels of availability, performance, and one-copy serializability. Deceit also supports a file version control mechanism. In contrast with many recent DFS efforts, Deceit can behave like a plain Sun Network File System (NFS) server and can be used by any NFS client without modifying any client software. The current Deceit prototype uses the ISIS Distributed Programming Environment for all communication and process group management, an approach that reduces system complexity and increases system robustness

SMiT: Local System Administration Across Disparate Environments Utilizing the Cloud

System administration can be tedious. Most IT departments maintain several (if not several hundred) computers, each of which requires periodic housecleaning: updating of software, clearing of log files, removing old cache files, etc. Compounding the problem is the computing environment itself. Because of the distributed nature of these computers, system administration time is often consumed in repetitive tasks that should be automated. Although current system administration tools exist, they are often centralized, unscalable, unintuitive, or inflexible. To meet the needs of system administrators and IT professionals, we developed the Script Management Tool (SMiT). SMiT is a web-based tool that permits administration of distributed computers from virtually anywhere via a common web browser. SMiT consists of a cloud-based server running on Google App Engine enabling users to intuitively create, manage, and deploy administration scripts. To support local execution of scripts, SMiT provides an execution engine that runs on the organization’s local machines and communicates with the server to fetch scripts, execute them, and deliver results back to the server. Because of its distributed asynchronous architecture SMiT is scalable to thousands of machines. SMiT is also extensible to a wide variety of system administration tasks via its plugin architecture