Control of objects using remotely generated magnetic fields has established itself as a viable option for 3D position control, though the objects being manipulated to date have largely been limited to soft and hard-magnetic objects that react to a static magnetic field. This limits the application to a small subset of materials. This work presents the first analytically derived model for 3D position control of any electrically conductive material subject to a time-varying magnetic field. By leveraging the induced eddy current and subsequent induced dipole, this model shows that conductive materials behave equivalently to diamagnetic materials and are therefore not subject to the limitations of Earnshaw's theorem, making stable, open-loop levitation possible. This is demonstrated by open-loop position control of a semi-buoyant aluminum sphere.

On the desktop, users are accustomed to having visible handles to objects that they want to organize, share, or manipulate. Web applications today feature many classes of such objects, like flight itineraries, products for sale, people, recipes, and businesses, but there are no interoperable handles for high-level semantic objects that users can grab. This paper proposes Clui, a platform for exploring a new data type, called a Webit, that provides uniform handles to rich objects. Clui uses plugins to 1) create Webits on existing pages by extracting semantic data from those pages, and 2) augmenting existing sites with drag and drop targets that accept and interpret Webits. Users drag and drop Webits between sites to transfer data, auto-fill search forms, map associated locations, or share Webits with others. Clui enables experimentation with handles to semantic objects and the standards that underlie them.

We present a middleware platform for assembling pervasive applications that demand fault-tolerance and adaptivity in distributed, dynamic environments. Unlike typical adaptive middleware approaches, in which sophisticated component model semantics are embedded into an existing, underlying platform (e.g., CORBA, COM, EJB), we propose a platform that imposes minimal constraints for greater flexibility. Such a tradeoff is advantageous when the platform is targeted by automatic code generators that inherently enforce correctness by construction. Applications are written as simple, single-threaded programs that assemble and monitor a set of distributed components. The approach decomposes applications into two distinct layers: (1) a distributed network of interconnected modules performing computations, and (2) constructor logic that assembles that network via a simple block-diagram construction API. The constructor logic subsequently monitors the configured system via a stream of high-level events, such as notifications of resource availability or failures, and consequently provides a convenient, centralized location for reconfiguration and debugging. The component network is optimized for performance, while the construction API is optimized for ease of assembly.

We describe an approach to automate certain high- level implementation decisions in a pervasive application, allowing them to be postponed until run time. Our system enables a model in which an application programmer can specify the behavior of an adaptive application as a set of open-ended decision points. We formalize decision points as goals, each of which may be satisfied by a set of scripts called Techniques. The set of Techniques vying to satisfy any goal is additive and may be extended at runtime without needing to modify or remove any existing techniques. Our system provides a framework in which Techniques may compete and interoperate at runtime in order to maintain an adaptive application. Technique development may be distributed and incremental, providing a path for the decentralized evolution of applications. Benchmarks show that our system imposes reasonable overhead during application startup and adaptation.

Many standardized hardware communication interfaces offer runtime flexibility and configurability at the cost of efficiency.An alternate approach is the use of a highly-efficien~minimal communication element with as much communication decision-making as possible done at compile time.NuMesh is a packaging and interconnect technology supporting high-bandwidth systolic communications on a 3D nearest-neighbor lattice; our goal is to combine Lego-like modularity with supercomputer performance.To date, the primary focus of the project has been the class of applications whose static communication patterns can be precompiled into independent and carefully choreographed finite state machines running on each node.Several extensions of the NuMesh to more general communication paradigms have been implemented, and the issues involved are under active exploration.This paper presents an overview of our approach, as well as an introduction to our current-generation prototype.We also discuss our software environment and simulation technology, and enumerate some of the applications and programming models we have developed to make full use of the capabdities of the NuMesh.