Space, Time and Machines

Concurrent computing machines and physical space-time

Concrete computing machines, either sequential or concurrent, rely on an intimate relation between computation and time. We recall the general characteristic properties of physical time and of present realizations of computing systems. We emphasize the role of computing interferences, i.e. the necessity to avoid them in order to give a causal implementation to logical operations. We compare syn...

Space Complexity in Infinite Time Turing Machines

A Time and Space Sharing Scheduler for Multiuser Parallel Machines

Time Machines Constructed from Anti-de Sitter Space

In classical general relativity there are many solutions of Einstein equations with closed timelike curves (CTCs) [1–6]. However, some early calculations of vacuum polarization in spacetimes with CTCs indicated that the renormalized stress-energy tensor diverged at the Cauchy horizon or the polarized hypersurfaces [7–10]. Hawking thus proposed the chronology protection conjecture which stated t...

Online State Space Model Parameter Estimation in Synchronous Machines

The purpose of this paper is to present a new approach based on the Least Squares Error method for estimating the unknown parameters of the nonlinear 3rd order synchronous generator model. The proposed method uses the mathematical relationships between the machine parameters and on-line input/output measurements to estimate the parameters of the nonlinear state space model. The field voltage is...