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1.
The anthropogenic impact on the Earth's ecosystems are leading to dramatic changes in ecosystem functioning and even to destruction of them. System analysis and the use of heuristic modeling can be an effective means to determine the main biological interactions and key factors that are of high importance for understanding the development of ecosystems. Cycling of limiting substances, induced by the external free energy flux, and trophic links interaction is the basis of the mathematical modeling studies presented in this paper. Mathematical models describe the dynamics of simplified ecosystems having different characteristics: 1) different degrees of biotic turnover closure (from open to completely closed); 2) different numbers of trophic links (including both "top-down", "bottom-up" regulation types); 3) different intensities of input-output flows of the limiting nutrient and its total amount in the system. Adaptive values of the changes of lower hierarchical levels (populational, trophic chain level) are to be estimated by integrity indices for total system functioning (e.g. NPP, total photosynthesis). The approach developed can be used for evaluating the contributions of lower hierarchical levels to the functioning of the higher hierarchical levels of the system. This approach may have value for determining biomanipulation management and their assessment.  相似文献   

2.
MELISSA is a micro-organisms based ecosystem conceived as a tool for understanding the behaviour of artificial ecosystems, and developing the technology for a future biological life support system for long term space mission. The driving element of MELISSA is the recovering of oxygen and edible biomass from waste (faeces, urea). Due to its intrinsic instability and the safety requirements of manned missions, an important control strategy is developed to pilot this system and to optimize its recycling performance. This is a hierarchical control strategy. Each MELISSA compartment has its local control system, and taking into account the states of other compartments and a global desired functioning point, the upper level determines the setpoints for each compartment. The developed approach is based on first principles models of each compartment (physico chemical equations, stoichiometries, kinetic rates, ...). Those models are used to develop a global simulator of the system (in order to study the global functioning). They are also used in the control strategy, which is a non linear predictive model based strategy. This paper presents the general approach of the control strategy of the loop from the compartment level up to the overall loop. At the end, some simulation and experimental results are presented.  相似文献   

3.
翼身融合(BWB)飞行器满足未来民用航空经济、绿色、低碳的运行需求,是重要的发展方向。针对BWB飞行器的飞行控制系统,对其安全性与系统设计进行了研究。给出基于系统理论的事故模型及过程,与相应的安全性分析,重点对BWB飞行器飞行控制系统内的复杂逻辑关系、不安全控制动作、危害致因进行分析;进行切换系统设计,给出低可靠先进系统和高可靠备用系统的设计过程,并分析切换逻辑;基于设计进行仿真验证。研究结果表明:系统理论过程分析方法能够支持BWB飞行器飞行控制系统复杂逻辑关系的安全隐患分析,同时所设计的飞行控制系统具有一定的安全性与实用性。  相似文献   

4.
Although soil is a component of terrestrial ecosystems, it is comprised of a complex web of interacting organisms, and therefore can be considered itself as an ecosystem. Soil microflora and fauna derive energy from plants and plant residues and serve important functions in maintaining soil physical and chemical properties, thereby affecting net primary productivity (NPP), and in the case of contained environments, the quality of the life support system. We have been using 3 controlled-environment facilities (CEF's) that incorporate different levels of soil biological complexity and environmental control, and differ in their resemblance to natural ecosystems, to study relationships among plant physiology, soil ecology, fluxes of minerals and nutrients, and overall ecosystem function. The simplest system utilizes growth chambers and specialized root chambers with organic-less media to study the physiology of plant-mycorrhizal associations. A second system incorporates natural soil in open-top chambers to study soil bacterial and fungal population response to stress. The most complex CEF incorporates reconstructed soil profiles in a "constructed" ecosystem, enabling close examination of the soil foodweb. Our results show that closed ecosystem research is important for understanding mechanisms of response to ecosystem stresses. In addition, responses observed at one level of biological complexity may not allow prediction of response at a different level of biological complexity. In closed life support systems, incorporating soil foodwebs will require less artificial manipulation to maintain system stability and sustainability.  相似文献   

5.
Using biotic turnover of substances in trophic chains, natural and artificial ecosystems are similar in functioning, but different in structure. It is necessary to have quantitative criteria to evaluate the efficiency of artificial ecosystems (AES). These criteria are dependent on the specific objectives for which the AES are designed. For example, if AES is considered for use in space, important criteria are efficiency in use of mass, power, volume (size) and human labor and reliability. Another task involves the determination of quantitative criteria for the functioning of natural ecosystems. To solve the problem, it is fruitful to use a hierarchical approach suitable for both individual links and the ecosystem as a whole. Energy flux criteria (principles) were developed to estimate the functional activities of biosystems at the population, community and ecosystem levels. A major feature of ecosystems as a whole is their biotic turnover of matter the rate of which is restricted by the lack of limiting substances. Obviously, the most generalized criterion is to take into account the energy flux used by the biosystem and the quantity of limiting substance included in its turnover. The use of energy flux by ecosystem, E(USED)--is determined from the photoassimilation of CO2 by plants (per time unit). It can be approximately estimated as the net primary production of photosynthesis (NPP). So, the ratio of CO2 photoassimilation rate (sometimes, measured as NPP) to the total mass of limiting substrate can serve as a main universal criterion (MUC). This MUC characterizes the specific cycling rate of limiting chemical elements in the system and effectiveness of every ecosystem including the global Biosphere. Comparative analysis and elaboration of quantitative criteria for estimation of natural and artificial ecosystems activities is of high importance both for theoretical considerations and for real applications.  相似文献   

6.
The role of key environmental factors in adaptation of spore-forming and non-spore-forming transgenic microorganisms (TM) have been studied in model ecosystems. Model TM Escherichia coli Z905 (bearing plasmid genes of bacterial luminescence Ap (r) Lux+) has been found to have a higher adaptation potential than TM Bacillus subtilis 2335/105 (bearing genes of human alpha 2-interferon Km (r) Inf+), planned for employment as a living vaccine under varying environmental conditions. Effects of abiotic factors on migration of natural and recombinant plasmids between microorganisms under model ecosystem conditions has been estimated. The transgenic microorganisms with low copy number survived better under introduction conditions in the microcosms studied. This trend has been shown to be independent of the microcosm type and its complexity. Grant numbers: 99-04-96017, 25, 00-07-9011.  相似文献   

7.
Uncertainty on carbon fluxes is determined by the uncertainties of ecosystem model structure, data and model parameter uncertainties and the temporal and spatial inaccuracy of the input data retrieval. The objective of this paper is to understand the error propagation and uncertainty of evaporative fraction (EF), soil moisture content (SMC) and water limited net ecosystem productivity (NEP). In this respect, C-Fix and spaceborne remote sensing are used for the ‘Brasschaat’ pixel. A simple model based on error theory and a Monte-Carlo approach are used. Different error scenarios are implemented to assess input uncertainty on EF, SMC and NEP as estimated with C-Fix.  相似文献   

8.
The development of efficient and safe Life Support Systems is one of the key drivers of the Global Solar System Exploration efforts. For each task performed by Life Support Systems (LSS) a great multitude of sub-system concepts exist and the challenge is to find the optimal combination of sub-systems for a given mission scenario. On a sub-system level the Equivalent Systems Mass (ESM) trade study approach is well suited to effectively compare sub-system options. On a system level in addition to ESM data time dependent sub-system performances within an overall system must be addressed. Criteria such as system stability, controllability and effectiveness must be considered in order to be able to assess the dynamic robustness of systems designed to the averages. In an effort to establish a dynamic simulation environment for this type of LSS optimizations the “Virtual Habitat” tool (V-HAB) is being developed at the Technical University of Munich (TUM). This paper introduces the most important part of the Virtual Habitat simulation, which is the human model.  相似文献   

9.
Considerations of design for life support systems.   总被引:1,自引:0,他引:1  
During the design phase for construction of artificial ecosystems, the following considerations are important. (1) Influences on living things in the ecosystem, such as lifestyles and physiological functions caused by stresses due to environmental changes. The long stay in the artificial ecosystem has a possibility to lead to evolutional change in the living things. (2) The system operation method in trouble, which relates to maintainability. (3) The system metamorphosis according to new technologies. (4) Route minimization of material flow that leads to an optimum system layout.  相似文献   

10.
编队构形设计是分布式卫星系统总体设计的关键问题,提出了一种编队构形优化设计方法。针对主星带辅星群体制分布式合成孔径雷达(SAR)超分辨率任务,从优化系统效能的角度出发,将满足超分辨性能的时间比率和分辨率改善因子作为编队构形优化设计的目标函数,以基线矢量为中间变量,建立了目标函数与编队卫星轨道根数的关系,并采用遗传算法求解。对不同卫星数目的编队系统进行了优化设计仿真,并与干涉车轮和钟摆编队构形方案进行了分析比较,数值结果验证了该优化设计方法的有效性和正确性。该设计方法还可改变优化目标函数,以适应用户的任务要求。  相似文献   

11.
In developing different types of biological life support systems for use in space or extreme environments on Eart, researchers should pay attention to the long term health or functional state of such systems. The difficulty of the task is compounded by the complexity of the links and structure to be found in biological systems. To solve the problem, a hierarchical approach may be used to estimate and monitor the health of the system as a whole and its individual links. Three levels in a typical hierarchy have been considered:
1. a. the organismic.
2. b. populations and communities.
3. c. the ecosystem.

Special attention has been given to the interactions between macro- and microorganisms. Microorganisms are considered the most suitable indicators of a system's health and its component links.  相似文献   


12.
Research of the effect of space environment on an ecosystem consisting of plants and animals is essential when they are to be positively used in space. Although there have been experiments on various organisms under space environment in the past, they mainly studied the effect of space environment on an individual organism or a single species. Microcosm is drawing attention as an experimental material of an ecosystem consisting of multiple species. The object in this research is to understand the nature of this network system called ecosystem. Thus, a mixed microorganism culturing system consisting of three types of microorganisms which form a minimum food chain system as a closed ecosystem (chlorella as the producer, bacteria as the decomposer, and rotifer as the consumer) was taken for the subject, on which to research the universal characteristics of ecosystems. From the results of experiments under the terrestrial environment, formation of colonies, which is an ecological structure, has been observed at its mature stage. The organisms form an optimal substance circulation system. Therefore, formation of colonies in simulation models is important. Many attempts have been made to create ecosystem models. For example, the Lotka-Volterra model forms a simultaneous equation with the differential equation expressing predator and prey relationship and many numerical calculations have been conducted on various ecosystems based on expanded L-V models. Conventionally, these top-down methods have been used. However, since this method only describes the average concentration of organisms that are distributed uniformly throughout the system and cannot express the spatial structure of the system, it was difficult to express ecosystem structures like colonies and density distributions. In actual ecosystems, there is heterogeneity in the number of individuals and in substance density, and this is thought to have great significance in ecosystems. Consequently, an individual-based model was used that applies rules to predator-prey relationship, suppression, production, self suppression, etc., of each species. It enabled the emergence of the overall system only by its local rules, and it was possible to reproduce colony generation. In addition, the transition and the ratio of populations for each species match well with experimental results.  相似文献   

13.
汽车板抗凹性评价体系及试验机系统   总被引:5,自引:0,他引:5  
抗凹性是评价汽车板使用性能的一项重要指标.建立了汽车板抗凹性评价体系,并从试验原理 、试件制备以及评估参数等方面作了系统的描述.在此基础上,开发了基于微机控制的专用 抗凹性试验机系统,详细介绍了试验机构成、测控系统以及加载系统.应用表明试验结果 稳定可靠.   相似文献   

14.
In order to study the relationship between the physiological metabolism of living things and the environmental factors such as the atmospheric contents and so on within the closed ecosystem, Closed Ecology Experiment Facilities (CEEF) were designed and now under construction based on the following concepts: (1) Individual sealed chambers (called modules) for the plant cultivation, animal breeding, human habitation and microbial waste treatment are to be constructed independently to be able to study the metabolic effects of each living thing on the environmental factors within closed ecosystem. (2) A chamber for the microbial waste treatment are to be replaced with two systems; wet oxidation reactors and chemical nitrogen fixation reactors. (3) Atmospheric control systems are to be independently attached to each module for stabilizing atmospheric contents in each module. (4) Any construction materials having the possibility to absorb oxygen and carbon dioxide are to be prohibited to use in each module for sustaining material balance. (5) Facilities have to be developed so that the closed plant and animal experiments can be done independently, as well as integrated experiments with plants and animals through exchanging foods, carbon dioxide, oxygen, condensed water and nutrient solution.  相似文献   

15.
空间实验室天地一体化故障诊断技术研究   总被引:4,自引:0,他引:4  
航天器故障诊断不仅可以提高航天器安全性和可靠性,而且可以节约航天器安全寿命期成本。文中详细阐述了空间实验室天地一体化故障诊断系统方案。整个故障诊断体系由在轨诊断系统和地面诊断系统组成,在轨诊断系统具有部分自主诊断能力,地面诊断系统又分为系统级故障诊断和分系统级故障诊断。强调了基于模型推理技术(特别是多信号建模技术)在空间实验室天地一体化故障诊断系统中的重要性;最后指出了当前需要深入研究的建模技术及故障诊断系统的组件化和网络化等关键技术。  相似文献   

16.
月球中继通信卫星系统发展综述与展望   总被引:3,自引:2,他引:3       下载免费PDF全文
张立华  吴伟仁 《深空探测学报》2018,5(6):497-505,568
中继通信是一些月球探测任务中必须解决的关键问题,特别是月球背面和两极地区的着陆和巡视探测任务以及载人登月任务。对国内外月球中继通信卫星的研究和发展情况进行了综述,在对月球中继通信任务需求分析的基础上,从中继通信体制选择、轨道选择等方面对月球中继通信任务的实现途径进行了分析,并对月球中继通信技术的未来发展进行了展望。  相似文献   

17.
A mathematical model was used to investigate the effect of cannibalism intensity on the net primary production and the dynamics of trophic links in an aquatic ecosystem characterized by cannibalism at the upper trophic level. A mathematical model of an aquatic ecosystem has been constructed, with the following principal trophic links: limiting nutrient concentration, producers (phytoplankton), nonpredatory and predatory zooplankton. The model takes into account the age structure of the predator and includes two age groups (the young and adults). The adult predators are cannibals feeding on both nonpredatory zooplankton and their own young, which consume phytoplankton. It has been found that when cannibalism intensity increases above a certain level, the concentrations of both adults and the young of the predators decrease. At the same time, the concentrations of the nonpredatory zooplankton and of nutrients increase, while the biomass of producers decreases. When the cannibalism intensity is low, the net primary production of the system increases to a certain level correlated with the increase in cannibalism intensity and drops sharply when the level of consumption of young is high. There is an optimal intensity of cannibalism, at which the productivity in the photosynthesis link is maximal.  相似文献   

18.
人控操作交会对接是指操作人员在远端通过遥操作方式控制追踪航天器进行交会对接,主要用于无人航天器自动交会对接系统故障条件下交会对接控制.简要介绍遥操作交会对接的基本概念,给出实现人控遥操作交会对接三种方案,设计一种易于工程实现的遥操作交会对接系统,分析关键技术并给出了解决方法;根据设计的系统方案,进行遥操作交会对接试验,试验结果表明设计方案合理可行.  相似文献   

19.
We describe the experimental system having maximal possible closure of material recycling in an ecosystem, including people and plants, which was carried out in a hermetically sealed experimental complex "BIOS-3", 315 m2 in volume. The system included 2 experimentators and 3 phytotrons with plants (total sowing area of 63 m2). Plants were grown with round-the-clock lamp irradiation with 130 Wm-2 PAR intensity. The plants production was food for people. Water exchange of ecosystem, as wall as gas exchange, was fully closed excluding liquids and gas samples taken for chemical analysis outside the system. The total closure of material turnover constituted 91%. Health state of the crew was estimated before, during and after the experiment. A 5-months period did not affect their health. The experiments carried out prove that the closed ecosystem of "man-plants" is a prototype of a life-support system for long-term space expeditions.  相似文献   

20.
基于HLA的防空导弹武器系统仿真平台研究   总被引:10,自引:2,他引:10  
介绍了一个以防空导弹武器系统为背景,基于高级体系结构(HLA, High Level Architecture)技术实现的包含虚拟现实技术的综合仿真平台.着重论述了该仿真平台的构成、开发过程及其关键技术,包括HLA、基于FEDEP(Federation Development and Execution Process)模式的开发过程,层次化软件结构、计算机生成兵力(CGF, Computer Generated Forces)技术、面向对象建模以及基于包围盒的碰撞检测等.  相似文献   

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