553 research outputs found
Comparison between Two-level and Three-level Based Multi-port Converter for Interconnected MVAC Microgrids
No full textIn this paper, two-level and three-level modules for a three-phase multi-port converter (MPC) are evaluated and compared regarding the number of components and semiconductor losses. The MPC connects two medium-voltage ac (MVAC) microgrids to a common storage unit. The two-level MPC unit comprises a full-bridge converter for the ac-side and an isolated triple active bridge (TAB) dc-dc converter connecting the three ports. The full-bridge is replaced by a three-level neutral point clamped converter in the three-level solution. The comparative study was performed using PLECS simulation
Optimal Modulation of Triple Active Bridge Converters by an Artificial-Neural- Network Approach
No full textIsolated multi-port converters can host loads and sources at different power and voltage levels to their ports by a single topology, giving potential merits in terms of power density and efficiency. However, the higher the number of ports, the higher the number of degrees of freedom in the modulation patterns. This high number of modulation variables complicates the optimization problem, making closed-form solutions impractical. This paper avoids the analytic solution to the optimization problem by proposing a data-driven solution. The presented approach is based on an artificial neural network (ANN) trained to minimize the rms value of the currents flowing through the switches and the transformer windings of a triple active bridge (TAB) converter. This minimization is achieved by determining suitable values of the duty-cycles for modulating the converter switches. The proposed ANN-based modulation is validated considering an experimental TAB prototype rated 5kW
Tools from statistical physics for systems biology and for genomics
No full textMy graduate studies involved three broad classes of problems, each of which are presented in different chapters of this thesis. The first two parts of my work were related to studying dynamics of biochemical networks. I studied a mean-field/stochastic model of epigenetic chromatin silencing in yeast. The model gives rise to different dynamical behaviors possible within the same molecular model and provides qualitative predictions that are being investigated experimentally. In another part of my work, I studied a model of segment polarity network in Drosophila and analyzed the parameter space of the system. I particularly studied the relation between the geometry of parameter space and the robustness of the network. I will show that, in addition to the volume, the geometry of this region has important consequences for the robustness and the fragility of a network. A major part of my PhD work involved applications of high-throughput sequencing technologies for extracting information at the genomic level. I present SOPRA, a new algorithm for exploiting the mate pair information for assembly of short reads. I have successfully applied SOPRA to real data and were able to assemble scaffolds of significant length with very few errors introduced in the process.Ph.D.Includes bibliographical referencesIncludes vitaby Adel Dayaria
Long-Term Cost Performance of Corrosion-Resistant Reinforcements in Structural Concrete
No full textCorrosion, which leads to the premature deterioration of reinforced concrete (RC)
structures, is increasingly an issue of global concern. Accordingly, corrosion-resistant
materials have emerged as alternative reinforcement solutions in concrete structures. Yet,
the high initial cost of such materials may mitigate their potential use. This paper reports
on the results of two life-cycle-cost-analysis (LCCA) studies that aim at verifying the
long-term cost performance of corrosion-resistant reinforcements in structural concrete.
The first study conducted a 100-year-based LCCA study to evaluate the relative cost
savings of structural concrete that combines seawater, recycled coarse aggregates, and
glass fiber-reinforced polymer (GFRP) reinforcement in high-rise buildings as compared
to a traditional reinforced concrete (i.e., freshwater-mixed, natural-aggregate, black-steelreinforced).
In the second study, a life-cycle-cost comparison was established among
four reinforcement alternatives, viz., conventional steel, epoxy-coated steel, stainless
steel, and GFRP for a RC water chlorination tank considering a 100-year study period.
The results of these two studies suggest that the use of corrosion-resistant reinforcement
(especially GFRP) in structural concrete may potentially lead to significant cost savings
in the long term: the net present cost of GFRP-RC structures was generally 40-50%
lower than that reinforced with black steel.The authors would like to acknowledge the fund received by the NPRP grant # NPRP
9-110-2-052 from Qatar National Research Fund (a member of Qatar Foundation). The
findings of this study are solely the responsibility of the author
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A proactive management algorithm for self healing mobile ad hoc networks
No full textThe ability to proactively manage mobile ad-hoc network (MANET) devices is critical for supporting complex services such as quality of service (QoS), security and access control in these networks. This research focuses on the problem of managing high dynamic and resource constrained MANET environments through the introduction of a novel Proactive Management Algorithm (PMA) for self healing MANETs. PMA is based on the effective integration of autonomous, predictive and adaptive distributed management strategies. Proactive management is achieved through the distributed analysis of the current performance of the mobile nodes utilizing an optimistic discrete event simulation method, which is used to predict the mobile nodes' future status and execute a proactive fault tolerant management scheme. PMA takes advantage of distributed parallel processing, flexibility and intelligence of active packets to minimize the management overhead, while adapting to the highly dynamic and resource-constrained nature of MANETs.The performance of the proposed PMA is validated using analytical performance analysis and simulation based on Active Virtual Network Management Protocol. The simulation results demonstrate that PMA not only significantly reduces management control overhead but also substantially improves both the performance and the stability under highly dynamic and limited resource conditions, which are typical for military, disaster relief and civilian applications in MANET environments.</p
Data-driven design of fault diagnosis systems: nonlinear multimode processes
No full textIn many industrial applications early detection and diagnosis of abnormal behavior of the plant is of great importance. During the last decades, the complexity of process plants has been drastically increased, which imposes great challenges in development of model-based monitoring approaches and it sometimes becomes unrealistic for modern large-scale processes. The main objective of Adel Haghani Abandan Sari is to study efficient fault diagnosis techniques for complex industrial systems using process historical data and considering the nonlinear behavior of the process. To this end, different methods are presented to solve the fault diagnosis problem based on the overall behavior of the process and its dynamics. Moreover, a novel technique is proposed for fault isolation and determination of the root-cause of the faults in the system, based on the fault impacts on the process measurements. Contents Process monitoring Fault diagnosis and fault-tolerant control Data-driven approaches and decision making Target Groups Graduate students and scientists of automatic control and process engineering Engineers in field of process control and monitoring, mechatronic About the Author Adel Haghani Abandan Sari is research assistant with Institute of Automation, university of Rostock. His research interests include data-driven process monitoring and fault-tolerant control with focus on large-scale industrial processes
Stiffness of Coupling Slabs in Shear Wall Buildings
No full textTitle: Stiffness of Coupling Slabs in Shear Wall Buildings, Author: Adel A. Mahmoud, Location: Thode In this thesis, a study was made on the coupling effect of floor slabs on the behaviour of shear wall structures . The slab coupled shear walls were analysed by the finite element technique to obtain the bending stiffness. Experimental verification was done on a small scale model of
steel walls coupled by a steel slab. Design curves to estimate the stiffness of the various slab coupled wall configurations are presented. In addition, a study was made on the influence of the dimensions and shapes of the
walls (plane walls, T-section walls and box core walls), wall openings, and slab dimensions on the effective width and stiffness of the connecting slab.ThesisMaster of Engineering (ME
Sustainable Concrete Using Seawater, Recycled Aggregates, and Non Corrosive Reinforcement
No full textUsing seawater and recycled concrete aggregate (RCA) in a concrete mix is potentially advantageous from a sustainability perspective. However, the high chloride levels expected in such a concrete mix demands the use of non-corrosive reinforcement in lieu of normal black steel to avoid corrosion problems. Glass fiber reinforced polymer (GFRP) is considered promising as an alternative reinforcement owing to its corrosion resistance and acceptable mechanical properties that minimize maintenance and repairs and extend service life. Yet, the relatively high initial cost of GFRP bars may mitigate its potential use. In view of that, the current thesis is aimed at verifying the safe and economic utilization of seawater, recycled concrete aggregate, and GFRP reinforcement to produce sustainable and efficient concrete structures. The main body of the thesis consists of five key studies. In the first study, an extensive experimental program was conducted to compare the fresh and hardened properties of freshwater- and seawater-mixed concretes. In the second study, the performance of concrete mixed with seawater and recycled coarse aggregates (at 100% replacement level) was experimentally investigated. The third study was carried out to experimentally examine the flexural performance of seawater-mixed recycled aggregate GFRP-reinforced concrete beams. In the fourth study, a life cycle cost analysis (LCCA) was performed (considering 100-year analysis period) to verify the cost performance of structural concrete combining seawater, RCA, and GFRP reinforcement for high-rise buildings as compared to the traditional reinforced concrete
(i.e., with freshwater, natural aggregates, and black steel reinforcement). The fifth study evaluates the cost effectiveness of different reinforcement alternatives in a concrete water chlorination tank using LCCA: a comparison was established between four concrete reinforcing materials, namely, black steel, epoxy-coated steel, stainless steel, and GFRP through a 100-year analysis period. The results of these five studies suggest the potential use of the proposed combination (seawater + RCA + GFRP reinforcement) to produce safe and economic concrete structures
Effects of Using Seawater and Recycled Coarse Aggregates on Plain Concrete Characteristics
No full textUsing seawater and/or recycled coarse aggregates (RCA) for concrete mixing is deemed
advantageous from a sustainability perspective. This paper reports on the results of an
experimental study on fresh and hardened properties of concrete mixed with seawater and
RCA. Three concrete mixtures were investigated, namely, Mix A (traditional concrete),
Mix B (concrete made with seawater), and Mix C (concrete made with seawater and
RCA). It was concluded that the use of seawater and/or RCA had a notable effect on
fresh concrete properties. Mix B concrete showed a slightly lower strength performance
than that of Mix A (<15%), whereas the strength of Mix C concrete had a significant drop
(~30%) compared to the reference (Mix A). The permeability performance of hardened
concrete for Mixes A and B was similar, whereas Mix C concrete showed 60% increase
in water absorption and 100% increase in chloride permeability as compared to Mix A
Comparative Carbon-Footprint Analysis of Residential Buildings with Different Structural Materials
No full textAn important step towards achieving sustainability goals in the construction sector is taken by developing solutions that adopt ‘greener’ structural materials for buildings. This paper establishes a comparison among four existing residential buildings in Sweden, that utilize different structural solutions, in terms of their global warming potential (GWP). The structural solutions compared are prefabricated reinforced concrete (RC), light timber frame, cross-laminated timber (CLT) panels, and CLT modular construction. For each building, a life cycle assessment (LCA) was performed to estimate the greenhouse gas (GHG) emissions attributable to material production. In general, the results of this study revealed climate benefits associated with timber-based construction, with approximately 50% savings on average in the GHG emissions per unit floor area of the buildings as compared to prefabricated RC construction. Finally, this effort demonstrates the significance of the structural material choice on the overall carbon footprint of a building, especially at the production stage
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