به نام خدا
Title: Numerical simulation and optimization of CO2 sequestration in saline aquifers
Authors: Zheming Zhang, Ramesh Agarwal
Abstract: With heightened concerns on CO2 emissions from coal fired electricity generation plants, there has been major emphasis in recent years on the development of safe and economical Carbon Dioxide Capture and Sequestration (CCS) technology worldwide. Saline reservoirs are attractive geological sites for CO2 sequestration because of their huge capacity for long term sequestration. Over the last decade, numerical simulation codes have been developed in US, Europe and Japan to determine a priori the CO2 storage capacity of a saline aquifer and to provide risk assessment with reasonable confidence before the actual deployment of CO2 sequestration can proceed with enormous investment. In US, the 2nd version of Transport of Unsaturated Groundwater and Heat (TOUGH2) numerical simulator has been widely used for this purpose. However at present, it does not have the ability to determine optimal parameters such as injection rate, injection pressure, injection depth for vertical and horizontal wells, etc. for optimization of the CO2 storage capacity and for minimizing the leakage potential by confining the plume migration. This paper describes the development of a “Genetic Algorithm (GA)” based optimizer for TOUGH2 that can be used by the industry with good confidence to optimize the CO2 storage capacity in a saline aquifer of interest. This new code including the TOUGH2 and the GA optimizer is designated as “GATOUGH2”. It has been validated by conducting simulations of three widely used benchmark problems by the CCS researchers worldwide: (a) study of CO2 plume evolution and leakage through an abandoned well, (b) study of enhanced CH4 recovery in combination with CO2 storage in depleted gas reservoirs, and (c) study of CO2 injection into a heterogeneous geological formation. The results of these simulations are in excellent agreement with those of other researchers using different codes. The validated code has been employed to optimize the proposed water-alternating-gas (WAG) injection scheme for (a) a vertical CO2 injection well and (b) a horizontal CO2 injection well, in order to optimize the CO2 sequestration capacity of an aquifer. The optimized calculations from GATOUGH2 are compared with the brute force nearly optimized results obtained by performing a large number of calculations. These comparisons demonstrate the significant efficiency and accuracy of GATOUGH2 as an optimizer compared to using TOUGH2 in a brute force manner. This capability holds a great promise in studying a host of other problems in CO2 sequestration such as how to optimally accelerate the capillary trapping, accelerate the dissolution of CO2 in water or brine, and immobilize the CO2 plume.
Publish Year: 2013
Published in: Computers and Fluids - Science Direct
Number of Pages: 9
موضوع: مهندسی مواد، متالورژی
ایران سای – مرجع مقالات علمی فنی مهندسی
حامی دانش بومی ایرانیان
به نام خدا
Title: Path Planning and Ground Control Station Simulator for UAV
Authors: Alain AJAMI, JeanFrancois BALMAT, JeanPaul GAUTHIER, Thibault MAILLOT
Abstract: In this paper we present a Universal and Interoper-able Ground Control Station (UIGCS) simulator for fixed androtary wing Unmanned Aerial Vehicles (UAVs), and all types ofpayloads. One of the major constraints is to operate and man-age multiple legacy and future UAVs, taking into account thecompliance with NATO Combined/Joint Services OperationalEnvironment (STANAG 4586). Another purpose of the station isto assign the UAV a certain degree of autonomy, via autonomousplanification/replanification strategies. The paper is organizedas follows.In Section 2, we describe the non-linear models of the fixed androtary wing UAVs that we use in the simulator.In Section 3, we describe the simulator architecture, which isbased upon interacting modules programmed independently.This simulator is linked with an open source flight simulator, tosimulate the video flow and the moving target in 3D. To concludethis part, we tackle briefly the problem of the Matlab/Simulinksoftware connection (used to model the UAV_s dynamic) with thesimulation of the virtual environment.Section 5 deals with the control module of a flight path of theUAV. The control system is divided into four distinct hierarchicallayers: flight path, navigation controller, autopilot and flightcontrol surfaces controller.In the Section 6, we focus on the trajectory planifica-tion/replanification question for fixed wing UAV. Indeed, one ofthe goals of this work is to increase the autonomy of the UAV. Wepropose two types of algorithms, based upon 1) the methods ofthe tangent and 2) an original Lyapunov-type method. Thesealgorithms allow either to join a fixed pattern or to track amoving target.Finally, Section 7 presents simulation results obtained on oursimulator, concerning a rather complicated scenario of mission.
Publish Year: 2013
Published in: Aerospace - IEEE
Number of Pages: 13
موضوع: مهندسی هوافضا
ایران سای – مرجع مقالات علمی فنی مهندسی
حامی دانش بومی ایرانیان
به نام خدا
Title: Construction of fuzzy ontologies from fuzzy XML models
Authors: Fu Zhang, Z.M. Ma, Li Yan
Abstract: The success and proliferation of the Semantic Web depends heavily on construction of Web ontologies. However, classical ontology construction approaches are not sufficient for handling imprecise and uncertain information that is commonly found in many application domains. Therefore, great efforts on construction of fuzzy ontologies have been made in recent years. In particular, XML is imposing itself as a standard for representing and exchanging information on the Web, topics related to the modeling of fuzzy data have become very interesting in the XML data context. Therefore, constructing fuzzy ontologies from fuzzy XML data resources may make the existing fuzzy XML data upgrade to Semantic Web contents, and the constructed fuzzy ontologies may be useful for improving some fuzzy XML applications.This paper proposes a formal approach and an automated tool for constructing fuzzy ontologies from fuzzy XML data resources. Firstly, we propose a formal definition of fuzzy XML models (including the document structure fuzzy DTDs and the document content fuzzy XML documents). On this basis, we propose a formal approach for constructing fuzzy ontologies from fuzzy XML models, i.e., transforming a fuzzy XML model (including fuzzy DTD and fuzzy XML document) into a fuzzy ontology. Also, we give the proof of correctness of the construction approach, and provide a detailed construction example. Furthermore, we implement a prototype tool called FXML2FOnto, which can automatically construct fuzzy ontologies from fuzzy XML models. Finally, in order to show that the constructed fuzzy ontologies may be useful for improving some fuzzy XML applications, we focus on investigating how to reason on fuzzy XML models (e.g., conformance, inclusion, and equivalence) based on the constructed fuzzy ontologies, and it turns out that the reasoning tasks of fuzzy XML models can be checked by means of the reasoning mechanism of fuzzy ontologies.
Publish Year: 2013
Published in: Knowledge-Based Systems - Science Direct
Number of Pages: 20
موضوع: XML، فازی
ایران سای – مرجع مقالات علمی فنی مهندسی
حامی دانش بومی ایرانیان
به نام خدا
Title: Structure learning for belief rule base expert system: A comparative study
Authors: Leilei Chang, Yu Zhou, Jiang Jiang, Mengjun Li, Xiaohang Zhang
Abstract: The Belief Rule Base (BRB) is an expert system which can handle both qualitative and quantitative information. One of the applications of the BRB is the Rule-base Inference Methodology using the Evidential Reasoning approach (RIMER). Using the BRB, RIMER can handle different types of information under uncertainty. However, there is a combinatorial explosion problem when there are too many attributes and/or too many alternatives for each attribute in the BRB. Most current approaches are designed to reduce the number of the alternatives for each attribute, where the rules are derived from physical systems and redundant in numbers. However, these approaches are not applicable when the rules are given by experts and the BRB should not be oversized. A structure learning approach is proposed using Grey Target (GT), Multidimensional Scaling (MDS), Isomap and Principle Component Analysis (PCA) respectively, named as GT–RIMER, MDS–RIMER, Isomap–RIMER and PCA–RIMER. A case is studied to evaluate the overall capability of an Armored System of Systems. The efficiency of the proposed approach is validated by the case study results: the BRB is downsized using any of the four techniques, and PCA–RIMER has shown excellent performance. Furthermore, the robustness of PCA–RIMER is further verified under different conditions with varied number of attributes.
Publish Year: 2013
Published in: Knowledge-Based Systems - Science Direct
Number of Pages: 14
موضوع: سیستمهای خبره
ایران سای – مرجع مقالات علمی فنی مهندسی
حامی دانش بومی ایرانیان
به نام خدا
Title: Information Fusion and Discounting Techniques for Decision Support in Aerospace
Authors: Fiona Browne , Yan Jin , Niall Rooney Hui Wang
Abstract: Decision makers are required to make critical decisions throughout all stages of a life-cycle in large-scale projects. These decisions are important as they impact upon the outcome and the success of projects. In this paper we present an evidential reasoning framework to aid decision-makers in the decision - making process. This approach utilizes the Dezert-Smarandache Theory (DSm) to fuse heterogeneous evidence sources that suffer from levels of uncertainty, imprecision and conflicts to provide beliefs for decision options. To analyze the impact that source reliability and priority has upon the decision making process a reliability discounting technique along with a priority discounting technique are applied. Application of the evidential reasoning framework is illustrated using a Case Study based in the Aerospace domain.
Publish Year: 2012
Published in: INDIN - IEEE
Number of Pages: 6
موضوع: مهندسی هوافضا، سیستمهای تصمیم یار
ایران سای – مرجع مقالات علمی فنی مهندسی
حامی دانش بومی ایرانیان