Information Flow in Logics in the Vicinity of BB

Situation theory, and channel theory in particular, have been used to provide motivational accounts of the ternary relation semantics of relevant, substructural, and various non-classical logics. Among the constraints imposed by channel-theory, we must posit a certain existence criterion for situations which result from the composites of multiple channels (this is used in modeling information flow). In associative non-classical logics, it is relatively easy to show that a certain such condition is met, but the problem is trickier in non-associative logics. Following Tedder (2017), where it was shown that the conjunction-conditional fragment of the logic B admits the existence of composite channels, I present a generalised ver- sion of the previous argument, appropriate to logics with disjunction, in the neighbourhood ternary relation semantic framework. I close by suggesting that the logic BB+(^I), which falls between Lavers' system BB+ and B+ , satisfies the conditions for the general argument to go through (and prove that it satisfies all but one of those conditions).

Direct Comparison of the Structural Compression Characteristics of Natural and Synthetic Fiber-Epoxy Composites: Flax, Jute, Hemp, Glass and Carbon Fibers

Recent decades have seen substantial interest in the use of natural fibers in continuous fiber reinforced composites, such as flax, jute and hemp. Considering potential applications, it is of particular interest how natural fiber composites compare to synthetic fiber composites, such as glass and carbon, and if natural fibers can replace synthetic fibers in existing applications. Many studies have made direct comparisons between natural and synthetic fiber composites via material coupon testing; however, few studies have made such direct comparisons of full structural members. This study presents compression tests of geometrically identical structural channel sections fabricated from fiber-epoxy composites of flax, jute, hemp, glass and carbon. Glass fiber composites demonstrated superior tension material coupon properties to natural fiber composites. However, for the same fiber mass, structural compression properties of natural fiber composite channels were generally equivalent to, or in some cases superior to, glass fiber composite channels. This indicates there is substantial potential for natural fibers to replace glass fibers in structural compression members. Carbon fiber composites were far superior to all other composites, indicating little potential for replacement with natural fibers.

Serial DF Relayed FSO Links over Mixture Gamma Turbulence Channels and Nonzero Boresight Spatial Jitter

Over the past few years, terrestrial free space optical (FSO) communication systems have demonstrated increasing research and commercial interest. However, due the signal’s propagation path, the operation of FSO links depends strongly on atmospheric conditions and related phenomena. One such significant phenomenon is the scintillation caused by atmospheric turbulence effects; in order to address the significant performance degradation that this causes, several statistical models have been proposed. Here, turbulence-induced fading of the received optical signal is investigated through the recently presented mixture Gamma distribution, which accurately describes the irradiance fluctuations at the receiver’s input of the FSO link. Additionally, at the same time, it significantly reduces the mathematical complexity of the expressions used for the description of composite channels with turbulence along with nonzero boresight pointing error-induced fading. In order to counterbalance the performance mitigation due to these effects, serial decode-and-forward relays are employed, and the performance of the system is estimated through derived mathematical expressions.