In the development of beyond-line-of-sight (BLOS) Unmanned Aerial Vehicle (UAV) systems, communication between the UAVs and the ground control station (GCS) is of critical importance. The commonly used economical wireless modules are restricted by the short communication range and are easily blocked by obstacles. The use of a communication relay system provides a practical way to solve these pr...

First-order logic (FOL) is undecidable — that is, no algorithm exists that can decide whether a formula of FOL is valid or not. However, there are various fragments of FOL that are known to be decidable. FO, the two-variable fragment of FOL, is one of such languages [1,2]. FO is a first-order language where formulas have maximally two variables, no function symbols, but possibly do have equalit...

Several models have been proposed for scheduling the preventive maintenance (PM) of complex repairable systems in industry. These are often application-speci"c and some make unrealistic assumptions about stationarity of the process and quality of repairs. We investigate two principal types of general model, which have wider applicability. The "rst considers "xed PM intervals and is based on the...

Research exists on using instructional gardening programs with school age children as a means of improving dietary quality and for obesity prevention. This article examines the potential use of instructional gardens in childcare settings to improving fruit and vegetable intake in young children. A qualitative study was conducted with childcare providers. Participants (n = 20) were recruited via...