Many military simulations and computer entertainment products share a need to model the ability of individual entities (men, tanks, planes, etc.) to see one another and to hide from one another in a 3D virtual environment. The traditional line-of-sight (LOS) visibility model can cause serious problems with hiding behavior. Three alternative visibility models and corresponding algorithms for com...

The present paper develops a novel strategy for the exploration of an unknown environment with a multirobot system. Contrary to most exploration problems, the topographical properties of the space need not be mapped. The algorithm we propose is inspired by methods used for complete coverage of an area, where all free space has to be physically covered by all robots. In the present paper it is r...

While both IR and THz/mmW wireless communications share some attributes such as line-of-sight signaling, their behaviors in response to various weather phenomena such as rain, fog, dust, and air turbulence can be quite different. The performance of mmW/THz and infrared freespace communication links are compared under the same weather conditions.

A multidisciplinary analysis is demonstrated for the NEXUS space telescope precursor mission. This mission was originally designed as an in-space technology testbed for the Next Generation Space Telescope (NGST). One of the main challenges is to achieve a very tight pointing accuracy with a sub-pixel line-of-sight (LOS) jitter budget and a root-mean-square (RMS) wavefront error smaller than =50...

Recently some pessimism has been expressed about our lack of progress in understanding quasars over the 50+ year since their discovery (Antonucci, 2013). It is worthwhile to look back at some of the progress that has been made—but still lies under the radar—perhaps because few people are working on optical/UV spectroscopy in this field. Great advances in understanding quasar phenomenology have ...

We have analyzed the behavior of a multiple element antenna system in an indoor environment based on the measurements taken in the Lucent Crawford Hill building with a system of 12 transmitters and 15 receivers. The parameters that we investigated were the distance between the transmitting and the receiving arrays, and the polarization of the transmitter/ receiver elements. Our measurements sho...

Wireless channel measurement results for 60 GHz within a closed metal cabinet are provided. A metal cabinet is chosen to emulate the environment within a mechatronic system, which have metal enclosures in general. A frequency domain sounding technique is used to measure the wireless channel for different volumes of the metal enclosure, considering both lineof-sight (LOS) and non-line-of-sight (...

Performance of Ultra-wideband (UWB) radios in non-line-of-sight (NLoS) environments has been a topic of interest among researchers, especially when it comes to indoor localization applications. It is known that NLoS propagation of electromagnetic waves can severely affect the localization accuracy. Despite the interest in indoor localization performance, it is still difficult to compare results...

A new transmission and detection technique namely Dual Diffuser Modulation (DDM) for free space optical (FSO) communication systems is proposed. FSO communication systems can provide the line-of-sight optical transmission with low cost and good security. However, the distance dependent atmospheric turbulence and path-loss affect widespread use of FSO systems and limit their application to short...