Khalifa University

About: Khalifa University is a education organization based out in Abu Dhabi, United Arab Emirates. It is known for research contribution in the topics: Computer science & Adsorption. The organization has 3752 authors who have published 10909 publications receiving 141629 citations.

Continuous cultivation of microalgae in photobioreactors as a source of renewable energy: Current status and future challenges

Abstract: Microalgae are promising sustainable energy sources for biodiesel production due to their rapid photosynthesis growth rate and capacity to be cultivated in wastewater, seawater, or freshwater. Moreover, microalgae could complete the entire growth cycle via photosynthesis reactions that convert light energy into renewable energy. The closed photobioreactor, PBR is resistant to infection from uninhabited algae species and allows frequent monitoring of various factors such as temperature, light intensity, and pH during the cultivation phase. Thus, this study focuses on continuous cultivation technology which produces higher biomass productivity with sustainable energy-saving operation as compared to batch culture. High productivity of microalgae biomass tends to accumulate higher concentrations of lipid and carbohydrates composition which is essential for the production of biofuels. The energy balance of numerous microalgae-based biofuels was discussed, and it was discovered that the net-energy ratio was greater than 1, indicating that the process is both commercially feasible and environmentally friendly. This study also summarizes the most recent discoveries on continuous cultivation constraints through photobioreactors, PBRs as well as potential challenges to tackle in scaling up the continuous sustainable culture mechanism. The research gaps, market opportunities, and future development directions of continuous photobioreactor systems are discussed to explore future development opportunities. A continuous photobioreactor, architecture is recommended for a pilot-scale trial, as a cost-benefit comparison would be beneficial in commercializing the framework.

Blockchain-Based Forward Supply Chain and Waste Management for COVID-19 Medical Equipment and Supplies

Abstract: The year 2020 has witnessed unprecedented levels of demand for COVID-19 medical equipment and supplies. However, most of today’s systems, methods, and technologies leveraged for handling the forward supply chain of COVID-19 medical equipment and the waste that results from them after usage are inefficient. They fall short in providing traceability, reliability, operational transparency, security, and trust features. Also, they are centralized that can cause a single point of failure problem. In this paper, we propose a decentralized blockchain-based solution to automate forward supply chain processes for the COVID-19 medical equipment and enable information exchange among all the stakeholders involved in their waste management in a manner that is fully secure, transparent, traceable, and trustworthy. We integrate the Ethereum blockchain with decentralized storage of interplanetary file systems (IPFS) to securely fetch, store, and share the data related to the forward supply chain of COVID-19 medical equipment and their waste management. We develop algorithms to define interaction rules regarding COVID-19 waste handling and penalties to be imposed on the stakeholders in case of violations. We present system design along with its full implementation details. We evaluate the performance of the proposed solution using cost analysis to show its affordability. We present the security analysis to verify the reliability of the smart contracts, and discuss our solution from the generalization and applicability point of view. Furthermore, we outline the limitations of our solution in form of open challenges that can act as future research directions. We make our smart contracts code publicly available on GitHub.

Structural and physical properties of the dust particles in Qatar and their influence on the PV panel performance.

Abstract: Recently, extensive R&D has been conducted, both by industry and academia, to significantly raise the conversion efficiency of commercial photovoltaic (PV) modules. The installation of PV systems aimed at optimizing solar energy yield is primarily dictated by its geographic location and installation design to maximize solar exposure. However, even when these characteristics have been addressed appropriately, there are other factors that adversely affect the performance of PV systems, namely the temperature-induced voltage decrease leading to a PV power loss, and the dust accumulation (soiling). The latter is the lesser acknowledged factor that significantly influences the performance of PV installations especially in the Middle East region. In this paper we report on the investigation of the structural and physical properties of the desert-dust particles in the State of Qatar. The dust particles were collected directly from the PV panels installed in desert environment and characterized by different techniques, including scanning electron, optical and atomic force microscopies, X-ray diffraction, energy-dispersive, UV-Vis, micro-Raman and Fourier transform infrared spectroscopy. The vibrating sample magnetometry analyses were also conducted to study the magnetic properties of the dust particles. The influence of the dust accumulation on the PV panel performance was also presented and discussed.