Large-scale Open Systems Research Articles

Fluvial-aeolian interactions in a partly confined reach of the Yarlung Tsangpo River, Tibet

Fluvial-aeolian interactions (FAI) exert a primary influence on landscape morphodynamics in arid regions. Such process interactions are well studied for large-scale open systems such as dryland deserts and plains, but little is known about FAI in partly confined valley settings. Here we show how aeolian sand availability and transport pathways and connectivity relationships influence morphodynamic interactions with fluvial processes in a braided reach of the Yarlung Tsangpo River in Southern Tibet, China. Analyses of remote sensing imagery, field data, and the hydrology record show how dune fields and wind systems influence the magnitude and frequency of channel change. While the dunes along the trunk stream have limited impact on river morphodynamics, mid-channel dune fields significantly decrease the frequency of channel adjustment. Combined impacts of valley winds and mountain-valley winds create aeolian sand ramps that stimulate sediment recirculation within this landscape setting.

Revisiting causality using stochastics: 2. Applications

In a companion paper, we develop the theoretical background of a stochastic approach to causality with the objective of formulating necessary conditions that are operationally useful in identifying or falsifying causality claims. Starting from the idea of stochastic causal systems, the approach extends it to the more general concept of hen-or-egg causality, which includes as special cases the classic causal, and the potentially causal and anti-causal systems. The framework developed is applicable to large-scale open systems, which are neither controllable nor repeatable. In this paper, we illustrate and showcase the proposed framework in a number of case studies. Some of them are controlled synthetic examples and are conducted as a proof of applicability of the theoretical concept, to test the methodology witha prioriknown system properties. Others are real-world studies on interesting scientific problems in geophysics, and in particular hydrology and climatology.

Revisiting causality using stochastics: 1. Theory

Causality is a central concept in science, in philosophy and in life. However, reviewing various approaches to it over the entire knowledge tree, from philosophy to science and to scientific and technological applications, we locate several problems, which prevent these approaches from defining sufficient conditions for the existence of causal links. We thus choose to determine necessary conditions that are operationally useful in identifying or falsifying causality claims. Our proposed approach is based on stochastics, in which events are replaced by processes. Starting from the idea of stochastic causal systems, we extend it to the more general concept of hen-or-egg causality, which includes as special cases the classic causal, and the potentially causal and anti-causal systems. Theoretical considerations allow the development of an effective algorithm, applicable to large-scale open systems, which are neither controllable nor repeatable. The derivation and details of the algorithm are described in this paper, while in a companion paper we illustrate and showcase the proposed framework with a number of case studies, some of which are controlled synthetic examples and others real-world ones arising from interesting scientific problems.

Biological contamination and its chemical control in microalgal mass cultures.

Microalgae are versatile sources of bioproducts, a solution for many environmental problems. However, and despite its importance, one of the main problems in large-scale cultures-the presence of contaminants-is rarely systematically approached. Contamination, or the presence of undesirable organisms in a culture, is deleterious for the culture and frequently leads to culture crashes. To avoid contamination, closed systems can be used; however, for very large-scale open systems, contamination is unavoidable and remediation procedures are necessary-ranging from physicochemical treatment to addition of biocidal substances. In all cases, early detection and culture monitoring are paramount. This article describes the biological contaminants, contamination mechanisms, and control systems used in open and closed cultures, discussing the latest advances and techniques in the area. It also discusses the complex interactions of algae with other microorganisms that can be expected in cultivation systems.

Sustainable production of toxin free marine microalgae biomass as fish feed in large scale open system in the Qatari desert

Mass cultivation of microalgae biomass for feed should be cost effective and toxin free. Evaporation loss in Qatar can be as high as 2cm/d. Hence, production of marine microalgae biomass in Qatar would also require mitigating water loss as there was only very limited groundwater reserve. To address these issues, a combination of four growth conditions were applied to a 25,000L raceway pond: locally isolated microalgae strain was selected which could grow in elevated salinity; strain that did not require silica and vitamins; volume of the culture would increase over time keeping denser inoculum in the beginning, and evaporation water loss would be balanced by adding seawater only. A local saline tolerant Nannochloropsis sp. was selected which did not require silica and vitamins. When the above conditions were combined in the pond, average areal biomass productivities reached 20.37g/m2/d, and the culture was not contaminated by any toxic microalgae.

CO2 biofixation and carbonic anhydrase activity in Scenedesmus obliquus SA1 cultivated in large scale open system

The present study deals with the large scale open system cultivation of the novel microalga: Scenedesmus obliquus SA1 (KC733762) previously isolated in our laboratory. SA1 strain was cultivated in open system at varying CO2 levels ranging from 0.03% to 35% (v/v) and subsequently the carbonic anhydrase activity (CA) and the biochemical properties were monitored. Maximum biomass concentration (1.39 ± 0.023 g L(-1)), CO2 fixation rate (97.65 ± 1.03 mg L(-1)d(-1)) and total CA activity (166.86 ± 3.30 E.U./mg chla) were obtained at 35% CO2. CA inhibitors: acetazolamide and ethoxyzolamide inhibited the external and internal enzyme activity in SA1. High CO2 levels were favorable for the accumulation of lipids and chlorophyll. The present results suggested that SA1 possessed high CO2 tolerance and high carbohydrate, lipid and chlorophyll content when cultivated in open system thus being suitable for CO2 mitigation in outdoor ponds and subsequent generation of value added products.

Agent long-term coalition credit

Agent trust researches become more and more important because they will ensure good interactions among the software agents in large-scale open systems. Moreover, individual agents often interact with long-term coalitions such as some E-commerce web sites. So the agents should choose a coalition based on utility and trust. Unfortunately, few studies have been done on agent coalition credit and there is a need to do it in detail. To this end, a long-term coalition credit model (LCCM) is presented. Furthermore, the relationship between coalition credit and coalition payoff is also attended. LCCM consists of internal trust based on agent direct interactions and external reputation based on agent direct observation. Generalization of LCCM can be demonstrated through experiments applied in both cooperative and competitive domain environment. Experimental results show that LCCM is capable of coalition credit computation efficiently and can properly reflect various factors effect on coalition credit. Another important advantage that is a useful and basic property of credit is that LCCM can effectively filter inaccurate or lying information among interactions.

TRAVOS: Trust and Reputation in the Context of Inaccurate Information Sources

In many dynamic open systems, agents have to interact with one another to achieve their goals. Here, agents may be self-interested, and when trusted to perform an action for another, may betray that trust by not performing the action as required. In addition, due to the size of such systems, agents will often interact with other agents with which they have little or no past experience. There is therefore a need to develop a model of trust and reputation that will ensure good interactions among software agents in large scale open systems. Against this background, we have developed TRAVOS (Trust and Reputation model for Agent-based Virtual OrganisationS) which models an agent’s trust in an interaction partner. Specifically, trust is calculated using probability theory taking account of past interactions between agents, and when there is a lack of personal experience between agents, the model draws upon reputation information gathered from third parties. In this latter case, we pay particular attention to handling the possibility that reputation information may be inaccurate.

객체지향 공간 모델에 기반한 지하수 관정 안전도 평가 시스템을 위한 유형적 분석

This paper is to define the method that develops the software In proper to application areas of Geographic Information Systems and design patterns according to functions and roles that implement the system for safety evaluation of the groundwater well based on an object oriented spatial model. In order to design the user interface of the groundwater well, this paper proposes the framework that should classify only requisite components adaptable to various application areas. By specifying De pattern appropriate to the application domain and designing the analysis pattern using the UML based on the object oriented methodology. this paper shah contribute to enhance the reuse of components that can develop and distribute a .large scale open system.

DAI betwixt and between: from 'intelligent agents' to open systems science

The authors discuss the development of open systems science (OSS) beginning with its roots in the fundamentals of concurrency. The nature of actors., which are the primitives of concurrency, is considered. The aim of OSS is to provide a foundation for effective technological solutions to the complex problems of large-scale open systems by providing a scientific discipline that focuses on issues of robustness, manageability, and scalability. In the large-scale open systems of the future, the focus with shift from centralized systems toward decentralized ones, with an emphasis on conflict processing. The evolution of this paradigm presents some challenges and some fruitful new ideas for distributed artificial intelligence that are discussed. >

Open Information Systems Semantics for distributed artificial intelligence

Distributed Artificial Intelligence (henceforth called DAI) deals with issues of large-scale Open Systems (i.e. systems which are always subject to unanticipated outcomes in their operation and which can receive new information from outside themselves at any time). Open Information Systems (henceforth called OIS) are Open Systems that are implemented using digital storage, operations, and communications technology. OIS Semantics aims to provide a scientific foundation for understanding such large-scale OIS projects and for developing new technology. The literature of DAI speaks of many important concepts such as commitment, conflict, negotiation, cooperation, distributed problem solving, representation, etc. However there is currently no framework for comparing the usage of such concepts in one publication with usage in other publications. Open Information System Semantics (henceforth called OIS Semantics) is a step toward remedying this problem by providing a framework which integrates methods from Sociology with methods from Concurrent Systems Science into a foundation that provides a framework for analyzing previous work in DAI and a powerful foundation for its further development. Deduction, one of the most powerful and well-understood methods for information systems, has recently been applied to foundational issues in DAI thereby raising important new issues and problems above and beyond those of applying deduction to the problems of classical AI. OIS Semantics provides answers to many important questions about the uses of deduction in OIS. It provides a characterization of Deduction that encompasses Nth-Order Logics, Meta-theories, Modal Logics, Circumscription, Default Logic, Autoepistemic Logic, Restricted Scope Nonmonotonic Logics, etc. OIS Semantics develops the concept of Deductive Indecision as a fundamental aspect of Deductive systems, thereby characterizing the scope and limits of Deduction for operational and representational activities in OIS. Negotiations play a fundamental role in OIS Semantics. They are creative processes that go beyond the capabilities of Deduction. OIS Semantics characterizes the role of Negotiation as a powerful method for increasing understanding of large-scale OIS projects. The ambitious goal of OIS Semantics for DAI is to provide an integrated foundation for Sociology and Concurrent Systems Science. This paper provides a snapshot of where we currently stand in the process of developing these foundations

Automatic on‐line growth estimation method for outdoor algal biomass production

An on-line measuring procedure for estimating productivity in outdoor algal cultures was developed and tested experimentally. The procedure is based on a previously described method for on-line measuring net O(2) production rate (OPR). The data obtained by this method was found to correlate well with the conventional procedures for estimation productivity by measuring the changes in biomass concentration in the culture. The new procedure seems to be superior to the latter since it can be carried out in an almost continuous way and can give immediate indication on the productivity. OPR could be used to monitor on-line the photosynthetic and/or respiration activity in small research fermentors or in large-scale open systems outdoors.