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: 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
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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: DNA extraction method with improved efficiency and specificity using DNA methyltransferase and click chemistry
Authors: Alexander B Artyukhin , YounHi Woo
Abstract: In an attempt to develop an alternative method to extract DNA from complex samples with much improved sensitivity and efficiency, here we report a proof-of-concept work for a new DNA extraction method using DNA methyltransferase (Mtase) and click chemistry. According to our preliminary data, the method has improved the current methods by (i) employing a DNA-specific enzyme, TaqI DNA Mtase, for improved selectivity, and by (ii) capturing the DNA through covalent bond to the functionalized surface, enabling a broad range of treatments yielding the final sample DNA with minimal loss and higher purity such that it will be highly compatible with downstream analyses. By employing Mtase, a highly DNA specific and efficient enzyme, and click chemistry, we demonstrated that as little as 0.1 fg of k-DNA (close to copy number 1) was captured on silica (Si)-based beads by forming a covalent bond between an azide group on the surface and the propargyl moiety on the DNA. This method holds promise in versatile applications where extraction of minute amounts of DNA plays critical roles such as basic and applied molecular biology research, bioforensic and biosecurity sciences, and state-of-the-art detection methods.
Publish Year: 2012
Published in: Analytical Biochemistry - Journal of Science Direct
Number of Pages: 6
موضوع: شیمی، بیوشیمی
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به نام خدا
Title: Qcompiler: Quantum compilation with the CSD method
Authors: YG Chen, JB Wang
Abstract: In this paper, we present a general quantum computation compiler, which maps any given quantum algorithm to a quantum circuit consisting a sequential set of elementary quantum logic gates based on recursive cosine sine decomposition. The resulting quantum circuit diagram is provided by directly linking the package output written in LaTeX to Qcircuit.tex We illustrate the use of the Qcompiler package through various examples with full details of the derived quantum circuits. Besides its accuracy, generality and simplicity, Qcompiler produces quantum circuits with significantly reduced number of gates when the systems under study have a high degree of symmetry.
Publish Year: 2013
Published in: Computer Physics Communications - Science Direct
Number of Pages: 13
موضوع: رایانش کوانتوم ، فیزیک
ایران سای – مرجع مقالات علمی فنی مهندسی
حامی دانش بومی ایرانیان