These false nuts are really the seed-bearing, hard, inner layer (endocarp) of a fruit called a drupe. In dry drupes the outer layer or husk sometimes splits open or withers. This outer husk is part of the ovary wall (pericarp), and the hard inner wall surrounding the seed represents the inner part of the pericarp.n chestnuts (Castanea) and beech (Fagus) the involucre is spiny, while in filberts and hazelnuts (Corylus), the involucre is leafy or tubular, depending on the exact species. This is a simplified classification of dry fruit types that follows most general botany textbooks and plant identification manuals.
A feedback loop is a common and powerful tool when designing a control system. Feedback loops take the system output into consideration, which enables the system to adjust its performance to meet a desired output response.
Mathematically, positive feedback is defined as a positive loop gain around a closed loop of cause and effect. That is, positive feedback is in phase with the input, in the sense that it adds to make the input larger.Positive feedback tends to cause system instability.hat is, A produces more of B which in turn produces more of A. In contrast, a system in which the results of a change act to reduce or counteract it has negative feedback. Both concepts play an important role in the field of Cybernetics.