Dynamic Considerations for Control of Closed Life Support Systems

Reliability of closed life support systems depend on their ability to continue supplying the crew's needs during perturbations and equipment failures. The dynamic considerations interact with the basic static design through the sizing of storages, the specification of excess capacities in processors, and the choice of system initial state. A very simple system flow model was used to examine the possibilities for system failures even when there is sufficient storage to buffer the immediate effects of the perturbation. Two control schemes are shown which have different dynamic consequences in response to component failures

Application of control theory to dynamic systems simulation

The application of control theory is applied to dynamic systems simulation. Theory and methodology applicable to controlled ecological life support systems are considered. Spatial effects on system stability, design of control systems with uncertain parameters, and an interactive computing language (PARASOL-II) designed for dynamic system simulation, report quality graphics, data acquisition, and simple real time control are discussed

A high-rate telemetry system for the Mariner Mars 1969 mission

High rate telemetry system for Mariner Mars 1969 missio

Control and modeling of a CELSS (Controlled Ecological Life Support System)

Research topics that arise from the conceptualization of control for closed life support systems which are life support systems in which all or most of the mass is recycled are discussed. Modeling and control of uncertain and poorly defined systems, resource allocation in closed life support systems, and control structures or systems with delay and closure are emphasized

An approach to the preliminary evaluation of Closed Ecological Life Support System (CELSS) scenarios and control strategies

Life support systems for manned space missions are discussed. A scenario analysis method was proposed for the initial step of comparing possible partial or total recycle scenarios. The method is discussed in detail

Internal versus external determinants of Schistosoma japonicum transmission in irrigated agricultural villages

Currently schistosomiasis transmission has been suppressed to low levels in many historically endemic areas of China by widespread use of praziquantel in human and bovine populations and application of niclosamide for snail control. However, re-emergent transmission has signalled the need for sustainable interventions beyond these repeated chemical interventions. To take advantage of ongoing investment in rural infrastructure, an index of schistosomiasis transmission potential is needed to identify villages where environmental modifications would be particularly effective. Based on a retrospective analysis of data from 10 villages in Sichuan Province, an index linked to the basic reproductive number is shown to have promise in meeting this need. However, a lack of methods for estimating the spatial components of the proposed metric and for estimating the import of cercariae and miracidia from neighbouring villages leads to significant uncertainty in its estimation. These findings suggest a priority effort to develop methods for measuring the free-swimming forms of the parasite in surface waters. This need is underscored by the high cost and limited sensitivity of current methods for diagnosing human infection and mounting evidence of the inadequacy of snail surveys to identify environments supporting low levels of transmission

Accessory Mineral Eu Anomalies in Suprasolidus Rocks: Beyond Feldspar

Accessory mineral Eu anomalies (Eu/Eu*) are routinely measured to infer changes in the amount of feldspar over time, allowing accessory mineral U‐Pb dates to be linked to the progressive crystallization of igneous and metamorphic rocks and, by extension, geodynamic processes. However, changes in Eu/Eu* can reflect any process that changes the relative availability of Eu2+ and Eu3+. We constructed partitioning budgets for Sm, Eu2+, Eu3+, and Gd in suprasolidus metasedimentary rocks to investigate processes that can influence accessory mineral Eu anomalies. We modeled three scenarios: (1) closed‐system, equilibrium crystallization; (2) fractionation of Eu by feldspar growth during melt crystallization; and (3) removal of Eu by melt extraction. In the closed‐system equilibrium model, accessory mineral Eu/Eu* changes as a function of fO2 and monazite stability; Eu/Eu* changes up to 0.3 over a pressure‐temperature range of 4–12 kbar and 700–950°C. Fractionation of Eu by feldspar growth is modeled to decrease accessory mineral Eu/Eu* by ~0.05–0.15 per 10 wt% feldspar crystallized. Melt extraction has a smaller effect; removal of 10% melt decreases accessory mineral Eu/Eu* in the residue by ≤0.05. Although these models demonstrate that fractionation of Eu by feldspar growth can be a dominant control on a rocks u budget, they also show that the common interpretation that Eu/Eu* only records feldspar growth and breakdown is an oversimplification that could lead to incorrect interpretation about the duration and rates of tectonic processes. Consideration of other processes that influence Eu anomalies will allow for a broader range of geological processes to be investigated by petrochronology.Plain Language SummaryMetamorphic rocks—rocks in which new minerals grew in response to increase in pressure and temperature related to deep burial or subduction—and igneous rocks—rocks that formed as magmas cool and crystallize—provide a direct record of how Earth’s continents have moved and changed through time. To read this record, geologists need to be able to measure the ages of metamorphism and magmatism: When did it happen? How long did it last? How does it relate to other rocks around the world? A common approach to addressing these questions is using U‐Pb dating of the minerals zircon, monazite, and apatite. The elements these minerals incorporate are indicative of how hot and how deep in the Earth they were when they grew. In this study we explore how geologists can use the concentrations of the element Europium (Eu) in these minerals to provide new insights into the geological meaning of U‐Pb dates, leading to more robust interpretations of Earth’s plate tectonic history.Key PointsEu anomalies in suprasolidus rocks record any process that changes the relative availability of Eu2+ and Eu3+, not just feldspar growthDisequilibrium is required for feldspar growth to strongly influence accessory mineral Eu anomaliesComparing accessory mineral Eu anomalies and Sr concentrations leads to more robust interpretation than evaluating Eu anomalies alonePeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/156481/1/ggge22268_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/156481/3/ggge22268.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/156481/2/ggge22268-sup-0001-2020GC009052-Text_SI-S01.pd

Telecommunications systems design techniques handbook

Handbook presents design and analysis of tracking, telemetry, and command functions utilized in these systems with particular emphasis on deep-space telecommunications. Antenna requirements are also discussed. Handbook provides number of tables outlining various performance criteria. Block diagrams and performance charts are also presented

Kleptoparasitic melees--modelling food stealing featuring contests with multiple individuals

Kleptoparasitism is the stealing of food by one animal from another. This has been modelled in various ways before, but all previous models have only allowed contests between two individuals. We investigate a model of kleptoparasitism where individuals are allowed to fight in groups of more than two, as often occurs in real populations. We find the equilibrium distribution of the population amongst various behavioural states, conditional upon the strategies played and environmental parameters, and then find evolutionarily stable challenging strategies. We find that there is always at least one ESS, but sometimes there are two or more, and discuss the circumstances when particular ESSs occur, and when there are likely to be multiple ESSs