It has been predicted theoretically that for some environments, the capacity of wireless MIMO systems can become very low even for uncorrelated signals; this effect has been termed keyhole or pinhole. In this paper the first unique measurements of this effect are presented. The measurements were performed in a controlled indoor environment that was designed to obtain a keyhole. We analyze limit...

Thermo-hydrodynamic phenomena which take place during laser welding or additive manufacturing processes as powder bed fusion, have been investigated for years, but recent advances in X-ray images and situ analysis highlighted new findings that are still under debate. Conduction-to-keyhole transition, more broadly, keyhole dynamics, typical cases, where complex coupling between hydrodynamic opti...

We present a closed form upper bound for the average pairwise error probabilities (PEP) of space-time codes for a keyhole channel. It is derived from the exact conditional PEP for given fading channel coefficients, using a moment generating function-based approach. We include simulation results for varying numbers of antennas which affirm that the proposed PEP serves as a tight bound for codes ...

Amanda Parkin, marketing manager at approved design and build consultant to the NHS for integrated theatres and digital video communications, OR Networks, explains how, with the help of the company and its specialist equipment, Northumbrian surgeons successfully established a two-way audio/video link to their counterparts at a hospital in the foothills of Mount Kilimanjaro to enable them to tra...

PURPOSE To develop a k-space formalism that provides a rationale for the design of variable-rate acquisition schemes for dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI). METHODS AND MATERIALS The formalism, termed spatio-temporal bandwidth-based (STBB) analysis, is demonstrated using a priori modeling of object and enhancement characteristics typically observed in DCE-MRI of br...

Channel capacity in a waveguide with mode coupling is limited by a keyhole effect caused by the propagation mechanism. The coupling among the propagating modes reduces the channel rank, and at sufficient distances between the transmitter and receiver, the channel rank converges to 1. Measurements of the received power and channel capacity along a hallway and in rooms beside it, show a decrease ...