The Polygon Package

The memoranda listed below describe the polygon package in its present state. For easy reference, these memoranda have been packaged together. Some of the material included is obsolete. In general, the later-dated material is better than the earlier material. Some specific hazards are indi~ated in the index below

Modular Timing Constraints for Delay-Insensitive Systems

This paper introduces ARCtimer, a framework for modeling, generating, verifying, and enforcing timing constraints for individual self-timed handshake components. The constraints guarantee that the component’s gate-level circuit implementation obeys the component’s handshake protocol specification. Because the handshake protocols are delayinsensitive, self-timed systems built using ARCtimer-verified components are also delay-insensitive. By carefully considering time locally, we can ignore time globally. ARCtimer comes early in the design process as part of building a library of verified components for later system use. The library also stores static timing analysis (STA) code to validate and enforce the component’s constraints in any self-timed system built using the library. The library descriptions of a handshake component’s circuit, protocol, timing constraints, and STA code are robust to circuit modifications applied later in the design process by technology mapping or layout tools. In addition to presenting new work and discussing related work, this paper identifies critical choices and explains what modular timing verification entails and how it works

Diamagnetism of YBa2Cu3O6+x crystals above Tc : evidence for Gaussian fluctuations

The magnetization of three high-quality single crystals of YBa2Cu3O6+x, from slightly overdoped to heavily underdoped, has been measured using torque magnetometry. Striking effects in the angular dependence of the torque for the two underdoped crystals, a few degrees above the superconducting transition temperature (Tc) are described well by the theory of Gaussian superconducting fluctuations using a single adjustable parameter. The data at higher temperatures (T) are consistent with a strong cut-off in the fluctuations for T ≳ 1.1Tc. Numerical estimates suggest that inelastic scattering could be responsible for this cut-off

Naturalized Communication and Testing

We ”naturalize” the handshake communication links of a self-timed system by assigning the capabilities of filling and draining a link and of storing its full or empty status to the link itself. This contrasts with assigning these capabilities to the joints, the modules connected by the links, as was previously done. Under naturalized communication, the differences between Micropipeline, GasP, Mousetrap, and Click circuits are seen only in the links — the joints become identical; past, present, and future link and joint designs become interchangeable. We also “naturalize” the actions of a self-timed system, giving actions status equal to states — for the purpose of silicon test and debug. We partner traditional scan test techniques dedicated to state with new test capabilities dedicated to action. To each and every joint, we add a novel proper-start-stop circuit, called MrGO, that permits or forbids the action of that joint. MrGO, pronounced “Mister GO,” makes it possible to (1) exit an initial state cleanly to start circuit operation in a delay-insensitive manner, (2) stop a running circuit in a clean and delay-insensitive manner, (3) single- or multi-step circuit operations for test and debug, and (4) test sub-systems at speed.We present a static control flow analysis used in the Simple Unified Policy Programming Language(Suppl) compiler to detect internally inconsistent policies. For example, an access control policy can decide to both “allow” and “deny” access for a user; such an inconsistency is called a conflict. Policies in Suppl. follow the Event-Condition-Action paradigm; predicates are used to model conditions and event handlers are written in an imperative way. The analysis is twofold; it first computes a superset of all conflicts by looking for a combination of actions in the event handlers that might violate a user-supplied definition of conflicts. SMT solvers are then used to try to rule out the combinations that cannot possibly be executed. The analysis is formally proven sound in Coq in the sense that no actual conflict will be ruled out by the SMT solvers. Finally, we explain how we try to show the user what causes the conflicts, to make them easier to solve

The ASPECTA toolkit : affordable Full Coverage Displays

Full Coverage Displays (FCDs) cover the interior surface of an entire room with pixels. FCDs make possible many new kinds of immersive display experiences - but current technology for building FCDs is expensive and complex, and software support for developing full-coverage applications is limited. To address these problems, we introduce ASPECTA, a hardware configuration and software toolkit that provide a low-cost and easy-to-use solution for creating full coverage systems. We outline ASPECTA’s (minimal) hardware requirements and describe the toolkit’s architecture, development API, server implementation, and configuration tool; we also provide a full example of how the toolkit can be used. We performed two evaluations of the toolkit: a case study of a research system built with ASPECTA, and a laboratory study that tested the effectiveness of the API. Our evaluations, as well as multiple examples of ASPECTA in use, show how ASPECTA can simplify configuration and development while still dramatically reducing the cost for creators of applications that take advantage of full-coverage displays.Postprin

Quantum fluctuations of the Chern-Simons theory and dynamical dimensional reduction

We consider a large-N Chern-Simons theory for the attractive bosonic matter (Jackiw-Pi model) in the Hamiltonian collective-field approach based on the 1/N expansion. We show that the dynamics of low-lying density excitations around the ground-state vortex configuration is equivalent to that of the Sutherland model. The relationship between the Chern-Simons coupling constant lambda and the Calogero-Sutherland statistical parameter lambda_s signalizes some sort of statistical transmutation accompanying the dimensional reduction of the initial problem.Comment: 10 pages, 2 figure

Evidence for Dirac nodes from quantum oscillations in SrFe2As2

We present a detailed study of quantum oscillations in the antiferromagnetically ordered pnictide compound SrFe2As2 as the angle between the applied magnetic field and crystalline axes is varied. Our measurements were performed on high-quality single crystals in a superconducting magnet, and in pulsed magnetic fields up to 60 T, allowing us to observe orbits from several small Fermi-surface pockets. We extract the cyclotron effective mass m☆ and frequency F for these orbits and track their values as the field is rotated away from the c axis. While a constant ratio of m☆/F is expected for a parabolic band, we observe deviations from this behavior. We conclude that this observation points to orbits derived from a band with Dirac dispersion near the Fermi level

Duality and quasiparticles in the Calogero-Sutherland model: Some exact results

The quantum-mechanical many-body system with the potential proportional to the pairwise inverse-square distance possesses a strong-weak coupling duality. Based on this duality, particle and/or quasiparticle states are described as SU(1,1) coherent states. The constructed quasiparticle states are of hierarchical nature.Comment: RevTeX, 10 page