Other affiliations: Korean Council for University Education, COMSATS Institute of Information Technology, King Fahd University of Petroleum and Minerals ...read more
Bio: Furqan Tahir is an academic researcher from Khalifa University. The author has contributed to research in topics: Desalination & Model predictive control. The author has an hindex of 11, co-authored 47 publications receiving 363 citations. Previous affiliations of Furqan Tahir include Korean Council for University Education & COMSATS Institute of Information Technology.
TL;DR: The authors discusses the main barriers hindering investment in clean energy production, highlights crucial incentives that could speed up investment processes, and examines several necessary strategies for the transition from fossil fuel-based energy to renewable sources.
Abstract: With the global population set to continue growing, the demand for energy will increase. Fossil fuel resources are in decline, and their use is associated with environmental destruction. This highlights the need for more investment in energy resources that can meet the global demand without harming the environment. Clean forms of energy, such as solar, wind, and hydropower, are both successful and readily available, yet investment in them has fluctuated. The affordability, ease of availability and technological maturity of oil in some regions has contributed to the slow uptake of investment in renewable energy projects. This paper discusses the main barriers hindering investment in clean energy production, highlights crucial incentives that could speed up investment processes, and examines several necessary strategies for the transition from fossil-fuel-based energy to renewable sources.
TL;DR: In this article, a survey of micro-nanoscale surface modification methods for condensation enhancement applications is presented, where the surface coating methods, applications and enhancement potential have been compared with respect to the heat transfer ability, durability, and efficiency.
Abstract: Condensation occurs in most of the heat transfer processes, ranging from cooling of electronics to heat rejection in power plants. Therefore, any improvement in condensation processes will be reflected in the minimization of global energy consumption, reduction in environmental burdens, and development of sustainable systems. The overall heat transfer coefficient of dropwise condensation (DWC) is higher by several times compared to filmwise condensation (FWC), which is the normal mode in industrial condensers. Thus, it is of utmost importance to obtain sustained DWC for better performance. Stability of DWC depends on surface hydrophobicity, surface free energy, condensate liquid surface tension, contact angle hysteresis, and droplet removal. The required properties for DWC may be achieved by micro–nanoscale surface modification. In this survey, micro–nanoscale coatings such as noble metals, ion implantation, rare earth oxides, lubricant-infused surfaces, polymers, nanostructured surfaces, carbon nanotubes, graphene, and porous coatings have been reviewed and discussed. The surface coating methods, applications, and enhancement potential have been compared with respect to the heat transfer ability, durability, and efficiency. Furthermore, limitations and prevailing challenges for condensation enhancement applications have been consolidated to provide future research guidelines.
TL;DR: A novel algorithm to compute low-complexity polytopic robust control invariant (RCI) sets, along with the corresponding state-feedback gain, for linear discrete-time systems subject to norm-bounded uncertainty, additive disturbances and state/input constraints is proposed.
Abstract: We propose a novel algorithm to compute low-complexity polytopic robust control invariant (RCI) sets, along with the corresponding state-feedback gain, for linear discrete-time systems subject to norm-bounded uncertainty, additive disturbances and state/input constraints. Using a slack variable approach, we propose new results to transform the original nonlinear problem into a convex/LMI problem whilst introducing only minor conservatism in the formulation. Through numerical examples, we illustrate that the proposed algorithm can yield improved maximal/minimal volume RCI set approximations in comparison with the schemes given in the literature.
TL;DR: In this article, the robust model predictive control (RMPC) of linear discrete time systems involving bounded disturbances and model-uncertainties along with hard constraints on the input and state is studied.
Abstract: We propose a novel procedure for the solution to the problem of robust model predictive control (RMPC) of linear discrete time systems involving bounded disturbances and model-uncertainties along with hard constraints on the input and state. The RMPC (outer) controller – responsible for steering the uncertain system state to a designed invariant (terminal) set – has a mixed structure consisting of a state-feedback component as well as a control-perturbation. Both components are explicitly considered as decision variables in the online optimization and the nonlinearities commonly associated with such a state-feedback parameterization are avoided by adopting a sequential approach in the formulation. The RMPC controller minimizes an upper bound on an H2/H∞-based cost function. Moreover, the proposed algorithm does not require any offline calculation of (feasible) feedback gains for the computation of the RMPC controller. The optimal Robust Positively invariant set and the inner controller – responsible for keeping the state within the invariant set – are both computed in one step as solutions to an LMI optimization problem. We also provide conditions which guarantee the Lyapunov stability of the closed-loop system. Numerical examples, taken from the literature, demonstrate the advantages of the proposed scheme.
13 Aug 2010
TL;DR: All rights reserved.
Abstract: All rights reserved. No part of the publication may be reproduced in any form by print, photoprint, microfilm or any other means without written permission from the publisher.
TL;DR: In this article, a review of thermal conduction mechanisms in polymers and polymer composites is presented, where the effects of different components of polymers on heat transfer are analyzed.
Abstract: It is of considerable scientific and technological importance to enhance the thermal conductivity coefficient (λ) values of the polymers and polymer composites. Limited understanding of heat transfer in polymers and polymer composites imposes restrictions on the designing and fabricating better thermally conductive polymers and polymer composites. This review attempts to help understand the thermal conduction mechanisms by analyzing the effects of different components in polymers and polymer composites on heat transfer. Factors of micro- and macro-characteristics, such as chain structures, interfaces, functionalization and processing techniques, etc., are all illustrated to elucidate their impacts on the thermal conductivities. In general, chain structures of polymers, intrinsic λ values of thermally conductive fillers and interfacial thermal resistances are the main and internal factors to determine the λ values of polymers and polymer composites. Meantime, processing and environmental factors are only auxiliary factors to improve the thermal conductivities. We expect this review will give some guidance to the future studies in thermally conductive polymers and polymer composites.
01 May 2013
TL;DR: The Solid State Solar-Thermal Energy Conversion Center (SSEEC) as discussed by the authors is a solid-state solar-thermal energy conversion center at the U.S. Dept. of Energy.
Abstract: United States. Dept. of Energy. Office of Basic Energy Sciences (Solid-State Solar-Thermal Energy Conversion Center)
TL;DR: A general outlook of the changing face of chemical synthesis is provided in this article through recent applications of continuous flow processing in both industry and academia to put into perspective the current position of Continuous flow processing, either as an alternative or potential combinatory technology for batch processing.
Abstract: A general outlook of the changing face of chemical synthesis is provided in this article through recent applications of continuous flow processing in both industry and academia. The benefits, major challenges and limitations associated with the use of this mode of processing are also given due attention as an attempt to put into perspective the current position of continuous flow processing, either as an alternative or potential combinatory technology for batch processing.
TL;DR: A conceptually different design approach is presented—based on principles derived from Namib desert beetles, cacti, and pitcher plants—that synergistically combines these aspects of condensation and substantially outperforms other synthetic surfaces.
Abstract: Controlling dropwise condensation is fundamental to water-harvesting systems, desalination, thermal power generation, air conditioning, distillation towers, and numerous other applications. For any of these, it is essential to design surfaces that enable droplets to grow rapidly and to be shed as quickly as possible. However, approaches based on microscale, nanoscale or molecular-scale textures suffer from intrinsic trade-offs that make it difficult to optimize both growth and transport at once. Here we present a conceptually different design approach—based on principles derived from Namib desert beetles, cacti, and pitcher plants—that synergistically combines these aspects of condensation and substantially outperforms other synthetic surfaces. Inspired by an unconventional interpretation of the role of the beetle’s bumpy surface geometry in promoting condensation, and using theoretical modelling, we show how to maximize vapour diffusion fluxat the apex of convex millimetric bumps by optimizing the radius of curvature and cross-sectional shape. Integrating this apex geometry with a widening slope, analogous to cactus spines, directly couples facilitated droplet growth with fast directional transport, by creating a free-energy profile that drives the droplet down the slope before its growth rate can decrease. This coupling is further enhanced by a slippery, pitcher-plant-inspired nanocoating that facilitates feedback between coalescence-driven growth and capillary-driven motion on the way down. Bumps that are rationally designed to integrate these mechanisms are able to grow and transport large droplets even against gravity and overcome the effect of an unfavourable temperature gradient. We further observe an unprecedented sixfold-higher exponent of growth rate, faster onset, higher steady-state turnover rate, and a greater volume of water collected compared to other surfaces. We envision that this fundamental understanding and rational design strategy can be applied to a wide range of water-harvesting and phase-change heat-transfer applications.