National University of Malaysia

About: National University of Malaysia is a education organization based out in Kuala Lumpur, Malaysia. It is known for research contribution in the topics: Population & Heat transfer. The organization has 26593 authors who have published 41270 publications receiving 552683 citations. The organization is also known as: NUM & Universiti Kebangsaan Malaysia.

Recent advances and emerging challenges in microbial electrolysis cells (MECs) for microbial production of hydrogen and value-added chemicals

Abstract: Microbial electrolysis cell (MEC) is a potentially attractive green technology to tackle the global warming and energy crisis, which employs electrochemically active bacteria to convert organic matter into hydrogen or a wide range of chemicals, such as methane, acetate, hydrogen peroxide, ethanol, and formic acid, without causing environmental pollution. Until now, probably the cleanest and the most efficient method of producing hydrogen has been MEC. However, this technology is still in its infancy period and poses various challenges towards up-scaling and widespread applications, such as such as lower hydrogen production rate (HPR), high internal resistance, complicated architecture, and expensive materials. New advances are needed in biofilm engineering, materials for electrodes and reactor configuration for successful real-world application of this technology. Thus, the present review deals with development of practical MEC technology and includes the following sections: firstly a general introduction to MECs; their operating principles, thermodynamics of MEC, and energy or voltage losses in the MEC system were provided. Followed by a section on the critical factors affecting MEC performance; microorganisms, anode, cathode, membrane or separator, fuel sources, the state-of-art MECs designs, other key operational factors, and its potential application in microbial production of value added products are discussed in detail. Afterwards, current challenges involved in developing practical MEC systems are highlighted, and outlooks for future development are also suggested. The review aims to assist researcher and engineers to gain fundamental understandings of MEC, and it also provides several future research directions and a road map on how to overcome the barriers, so the MEC technology can be further advanced and applied in larger scale.

WCRP COordinated Regional Downscaling EXperiment (CORDEX): A diagnostic MIP for CMIP6

Abstract: . The COordinated Regional Downscaling EXperiment (CORDEX) is a diagnostic model intercomparison project (MIP) in CMIP6. CORDEX builds on a foundation of previous downscaling intercomparison projects to provide a common framework for downscaling activities around the world. The CORDEX Regional Challenges provide a focus for downscaling research and a basis for making use of CMIP6 global climate model (GCM) output to produce downscaled projected changes in regional climates and assess sources of uncertainties in the projections, all of which can potentially be distilled into climate change information for vulnerability, impacts and adaptation studies. CORDEX Flagship Pilot Studies advance regional downscaling by targeting one or more of the CORDEX Regional Challenges. A CORDEX-CORE framework is planned that will produce a baseline set of homogeneous high-resolution, downscaled projections for regions worldwide. In CMIP6, CORDEX coordinates with ScenarioMIP and is structured to allow cross comparisons with HighResMIP and interaction with the CMIP6 VIACS Advisory Board.

A review of islanding detection techniques for renewable distributed generation systems

Abstract: Islanding detection of distributed generations (DGs) is one of the most important aspects of interconnecting DGs to the distribution system. Islanding detection techniques can generally be classified as remote methods, which are associated with islanding detection on the utility sides, and local methods, which are associated with islanding detection on the DG side. This paper presents a survey of various islanding detection techniques and their advantages and disadvantages. The paper focused on islanding detection using a conventional and intelligent technique. A summary table that compares and contrasts the existing methods is also presented.

Ion exchange membranes as separators in microbial fuel cells for bioenergy conversion: A comprehensive review

Abstract: The urgent need to address the twin problems of the modern world, energy insecurity caused by fossil fuel depletion and climate change caused by global warming from carbon dioxide emission and the greenhouse effect has led to among other things the emergence of fuel cell technology as a green energy technology that could generate cleaner and highly efficient energy. Microbial fuel cell (MFC), an emerging dual function, bioenergy conversion device, that not only treats wastewater but also generates electricity, has caught much attention of both fuel cell and bioenergy researchers. Until today, the commercialization of MFC has been restricted mainly due to its high cost and low power density. Many challenges still remain to be conquered, in order to improve the performance and commercialization of MFC. It is generally known that ion exchange membrane in MFC is one of the main factors that could significantly affect the cost and performance of MFC. This review provides an overview of several important membrane characteristics, which include membrane internal resistance, membrane biofouling, pH splitting, oxygen diffusion, and substrate loss across the membrane. The negative impact of these characteristics on MFC performance, are discussed. Moreover, this review concerns the types of membrane that have been applied in MFC systems, such as cation exchange membranes, anion exchange membranes, membraneless technology, polymer/composite membranes, and porous membranes. The future trend of membrane development for MFC applications is also discussed.