Integrated Application of Active Controls (IAAC) technology to an advanced subsonic transport project: Current and advanced act control system definition study. Volume 2: Appendices

The current status of the Active Controls Technology (ACT) for the advanced subsonic transport project is investigated through analysis of the systems technical data. Control systems technologies under examination include computerized reliability analysis, pitch axis fly by wire actuator, flaperon actuation system design trade study, control law synthesis and analysis, flutter mode control and gust load alleviation analysis, and implementation of alternative ACT systems. Extensive analysis of the computer techniques involved in each system is included

Integrated Application of Active Controls (IAAC) technology to an advanced subsonic transport project: Current and advanced act control system definition study, volume 1

An active controls technology (ACT) system architecture was selected based on current technology system elements and optimal control theory was evaluated for use in analyzing and synthesizing ACT multiple control laws. The system selected employs three redundant computers to implement all of the ACT functions, four redundant smaller computers to implement the crucial pitch-augmented stability function, and a separate maintenance and display computer. The reliability objective of probability of crucial function failure of less than 1 x 10 to the -9th power per flight of 1 hr can be met with current technology system components, if the software is assumed fault free and coverage approaching 1.0 can be provided. The optimal control theory approach to ACT control law synthesis yielded comparable control law performance much more systematically and directly than the classical s-domain approach. The ACT control law performance, although somewhat degraded by the inclusion of representative nonlinearities, remained quite effective. Certain high-frequency gust-load alleviation functions may require increased surface rate capability

Lower and upper probabilities in the distributive lattice of subsystems

yesThe set of subsystems ∑ (m) of a finite quantum system ∑(n) (with variables in Ζ(n)) together with logical connectives, is a distributive lattice. With regard to this lattice, the ℓ(m | ρn) = Tr ((m) ρn ) (where (m) is the projector to ∑(m)) obeys a supermodularity inequality, and it is interpreted as a lower probability in the sense of the Dempster–Shafer theory, and not as a Kolmogorov probability. It is shown that the basic concepts of the Dempster–Shafer theory (lower and upper probabilities and the Dempster multivaluedness) are pertinent to the quantum formalism of finite systems

MASTREE+ : time-series of plant reproductive effort from six continents

Significant gaps remain in understanding the response of plant reproduction to environmental change. This is partly because measuring reproduction in long-lived plants requires direct observation over many years and such datasets have rarely been made publicly available. Here we introduce MASTREE+, a data set that collates reproductive time-series data from across the globe and makes these data freely available to the community. MASTREE+ includes 73,828 georeferenced observations of annual reproduction (e.g. seed and fruit counts) in perennial plant populations worldwide. These observations consist of 5971 population-level time-series from 974 species in 66 countries. The mean and median time-series length is 12.4 and 10 years respectively, and the data set includes 1122 series that extend over at least two decades (≥20 years of observations). For a subset of well-studied species, MASTREE+ includes extensive replication of time-series across geographical and climatic gradients. Here we describe the open-access data set, available as a.csv file, and we introduce an associated web-based app for data exploration. MASTREE+ will provide the basis for improved understanding of the response of long-lived plant reproduction to environmental change. Additionally, MASTREE+ will enable investigation of the ecology and evolution of reproductive strategies in perennial plants, and the role of plant reproduction as a driver of ecosystem dynamics

Data from: Burning for enhanced non-timber forest product yield may jeopardize the resource base through interactive effects

Non-timber forest product (NTFP) harvest is frequently accompanied by resource management practices that interact with the harvesting itself, other disturbances and abiotic conditions. These interactions, in turn, lead to diverse environmental effects. Few studies focus on these practices in the context of harvesting NTFPs, product properties and environmental impacts, including biological invasions. In Pine woodlands in Eastern Bhutan, Cymbopogon flexuosus East Indian Lemon Grass is harvested and distilled to obtain essential oil, an economically important NTFP. Prescribed fires are applied in late winter (before annual harvest in summer) to induce regeneration of new tillers with increased essential oil content. This practice is based on local ecological knowledge and renders the utilization of C. flexuosus economically viable. On two sites with contrasting stand structure, we evaluated the effects of different prescribed burning regimes (no burning vs. burning with two levels of frequency and intensity) on the sustainability of annually harvested C. flexuosus, regarding cover, biomass yield, essential oil yield and quality. At the same time, we evaluated the effects of prescribed burning on the spread of the invasive shrub Chromolaena odorata. Cymbopogon flexuosus biomass declined over time, likely as a result of harvesting. In more closed stands, it was moreover marginally negatively influenced by fire. We confirmed local ecological knowledge regarding significantly higher essential oil yield on burned plots, without differences between fire regimes. In open stands, fire led to rapid expansion of C. odorata, specifically with frequently applied, higher intensity fires. Additionally, the spread of C. odorata showed adverse effects on C. flexuosus cover. Synthesis and applications. Our results highlight the importance of studying the wider impacts of non-timber forest product (NTFP) harvest. We confirmed local ecological knowledge that fire increases lemon grass essential oil yield, making prescribed burning an attractive land management tool for farmers. Nevertheless, the practice of annual harvesting may lead to resource decline that may be exacerbated by fire in closed stands. Caution needs to be practiced on open sites where invasive C. odorata may spread rapidly after fires. Management needs to focus on preventing concentration of annual harvesting and associated prescribed burning in the same areas. Amending national forestry rules to legalize fire as a land management tool can support local economies and potentially prevent wildfires that regularly devastate human infrastructure across eastern Bhutan