In optical communications, two measures of efficiency are commonly at odds. The first is the photon information efficiency (in bits/photon) which measures the information that each detected photon conveys; the second is the spectral efficiency (in bits/s/Hz) which measures the bit rate achieved under limited bandwidth. One interesting communication protocol which can simultaneously obtain high ...

Free-space communication links are severely affected by atmospheric turbulence, which causes degradation in the transmitted signal. One of the most common solutions to overcome this is to exploit diversity. In this approach, information is sent in parallel using two or more transmitters that are spatially separated, with each beam therefore experiencing different atmospheric turbulence, lowerin...

This paper describes the design trade-offs presented in DC-DC power converters used in space applications. The major concern, in the design of power supplies for space applications, is to obtain a very high reliability level, which can be very difficult to quantify, considering the relatively low production quantities involved. Space converters have to deal with radiation effects, vacuum enviro...

Suppose that a static-state feedback stabilizes a continuous-time linear infinite-dimensional control system. We consider the following question: if we construct a sampled-data controller by applying an idealized sample-andhold process to a continuous-time stabilizing feedback, will this sampled-data controller stabilize the system for all sufficiently small sampling times? Here the state space...

Empirical Mode Decomposition in 2-D space and time: a tool for space-time rainfall analysis and nowcasting S. Sinclair and G. G. S. Pegram Civil Engineering, University of KwaZulu-Natal, Durban, South Africa Received: 23 December 2004 – Accepted: 9 February 2005 – Published: 10 February 2005 Correspondence to: S. Sinclair ([email protected]) © 2005 Author(s). This work is licensed under a Cr...

-This paper addresses the decoupled control of the nonlinear, multiinput-multioutput, and highly coupled space station furnace facility (SSFF) thermal control system. Sliding mode control theory, a subset of variable-structure control theory, is employed to increase the performance, robustness, and reliability of the SSFF's currently designed control system. This paper presents the nonlinear th...

A four dimensional systematic mathematical approach for investigating propagation and coupling of wave modes in a slowly varying (in all space directions and time) anisotropic, absorbing plasma is represented. The formalism is especially useful for energy considerations of the waves. It is applicable to general cases of mode conversion in plasmas with general geometries of space-time and magnet...

Design of gain-scheduled controllers has attracted wide attention in H∞ control. Within the framework of 1-optimal control, a novel method for gain-scheduled output-feedback control has been proposed recently using a special control structure. This paper extends this method to more general linear parameter-varying systems. Furthermore an explicit way of constructing the resulting gain-scheduled...

We introduce a novel visual display paradigm through the use of controllable moving visible objects in physical space. Spaxels is a conjugation of "space" and "pixels". It takes the notion of a pixel, and frees it from the confines of a static two-dimensional matrix of a screen or projection surface to move three dimensionally in space. Spaxels extend the notion of Voxels, volumetric pixels, in...