Greek Lakes: Limnological overview

The Institute of Inland Waters in Greece has investigated the physical, chemical and biological characteristics of major Greek lakes, with regard to water use, quality and trophic status. Based on this and other limnological investigations, Greek lakes can be divided into three categories: warm monomictic deep lakes, warm monomictic shallow lakes, and dimictic shallow lakes. The water quality of some Greek lakes demonstrates the presence of high concentrations of nutrients and heavy metals, with reduced concentrations of diluted oxygen. High concentrations of ammonia, nitrate and phosphate are found in many lakes, while anaerobic hypolimnia are usually found in shallow lakes. Phosphorus is the main nutrient responsible for eutrophication because it is the limiting factor in most of the lakes that were investigated.     

Big data and business analytics ecosystems: paving the way towards digital transformation and sustainable societies

The digitalization process and its outcomes in the 21st century accelerate transformation and the creation of sustainable societies. Our decisions, actions and even existence in the digital world generate data, which offer tremendous opportunities for revising current business methods and practices, thus there is a critical need for novel theories embracing big data analytics ecosystems. Building upon the rapidly developing research on digital technologies and the strengths that information systems discipline brings in the area, we conceptualize big data and business analytics ecosystems and propose a model that portraits how big data and business analytics ecosystems can pave the way towards digital transformation and sustainable societies, that is the Digital Transformation and Sustainability (DTS) model. This editorial discusses that in order to reach digital transformation and the creation of sustainable societies, first, none of the actors in the society can be seen in isolation, instead we need to improve our understanding of their interactions and interrelations that lead to knowledge, innovation, and value creation. Second, we gain deeper insight on which capabilities need to be developed to harness the potential of big data analytics. Our suggestions in this paper, coupled with the five research contributions included in the special issue, seek to offer a broader foundation for paving the way towards digital transformation and sustainable societies     

Lithium-Ion Battery Separators for Ionic-Liquid Electrolytes: A Review

Ionic liquids (ILs) are widely studied as a safer alternative electrolyte for lithium-ion batteries. The properties of IL electrolytes compared to conventional electrolytes make them more thermally stable, but they also have poor wetting with commercial separators. In a lithium-ion battery, the electrolyte should completely wet out the separator and electrodes to reduce the cell internal resistance. Investigations of cell materials with IL electrolytes have shown that the wetting issues in IL–electrolyte cells are most likely due to poor separator compatibility, not electrode compatibility. A compatible separator must be developed before IL electrolytes can be used in commercial lithium-ion batteries. Herein, separators for IL electrolytes, including commercial and novel separators, are reviewed. Separators with different processing methods, polymers, additives, and different IL electrolytes are considered. Collated, the separator studies show a strong correlation between ionic conductivity and membrane porosity, even more than the electrolyte type. The challenge of a suitable separator for IL electrolytes is not solved yet. Herein, it is revealed that a separator for IL electrolytes will most likely require a combination of high thermal and mechanical stability polymer, ceramic additives, and an optimized manufacturing process.     

Multimedia retrieval based on non-linear graph-based fusion and partial least squares regression

Multimedia Tools and Applications - Heterogeneous sources of information, such as images, videos, text and metadata are often used to describe different or complementary views of the same...     

Evaluating alternative Frequentist inferential approaches for optimal order quantities in the newsvendor model under Exponential demand

Three estimation policies for the optimal order quantity of the classical newsvendor model when the demand is Exponentially distributed are evaluated in this paper. The evaluation is performed analytically for different combinations of sample sizes and values of the requested critical fractile. The statistical measures that have been chosen to perform the evaluation are (a) the actual critical fractile, namely, the actual probability for the estimated order quantities to meet the demand of the period, (b) the mean square error of the estimators for the optimal order quantity, and (c) the range of deviations of estimated order quantities from the optimal order quantity, provided that the probability of taking such a range is the same for the three estimation policies. For small and moderate sample sizes, no estimation policy predominates over the other two approaches, and the choice should be made on a subjective base according to the individual preferences of researchers or practitioners.     

Hollow lithiated metal oxide particles as lithium-ion battery cathode materials

We report the synthesis and characterization of the hollow micrometer-sized (Mn_0.5Ni_0.4Co_0.1)CO₃ precursor, and one of its promising lithium-enriched phases. The chemical composition of the resulting lithiated final material was Li_1.2(Mn_0.5Ni_0.4Co_0.1)O_2+y. Lithium half cells with cathodes comprised of these hollow particles as the active intercalation material showed a reversible capacity of 183 mAh/g when cycled between 2.0 V and 4.6 V. X-ray diffraction patterns and the electrochemical data of Li_1.2(Mn_0.5Ni_0.4Co_0.1)O_2+y were consistent with the existence of the Li₂MnO₃-type integrated component that was activated during the initial charging of the cells. The results presented herein demonstrate a method to synthesize multicomponent, multiphase materials with hollow internal morphologies that can reversibly and stably be cycled with high gravimetric capacities as the active cathode material in lithium-ion batteries.     

Active control of frequency varying disturbances in a diesel engine

In this paper a method for active vibration isolation of frequency varying tonal disturbances in an engine mounted on a raft is presented. An adaptive nonlinear control algorithm with frequency tracking is introduced to tackle this problem. The studied process is a true MIMO-system with strong cross-couplings and high background noise level. The controller performance is first validated by extensive simulations and then by test bed implementation. It is shown that the proposed method is robust to measurement noise and additional output disturbances, while yielding a high level of vibration suppression with fast convergence rate.     

Prospects for sustainability of pig production in relation to climate change and novel feed resources

Pig production systems provide multiple benefits to humans. However, the global increase in meat consumption has profound consequences for our earth. This perspective describes two alternative scenarios for improving the sustainability of future pig production systems. The first scenario is a high input–high output system based on sustainable intensification, maximizing animal protein production efficiency on a limited land surface at the same time as minimizing environmental impacts. The second scenario is a reduced input–reduced output system based on selecting animals that are more robust to climate change and are better adapted to transform low quality feed (local feeds, feedstuff co-products, food waste) into meat. However, in contrast to the first scenario, the latter scenario results in reduced predicted yields, reduced production efficiency and possibly increased costs to the consumer. National evaluation of the availability of local feed and feedstuff co-product alternatives, determination of limits to feed sourced from international markets, available land for crop and livestock production, desired production levels, and a willingness to politically enforce policies through subsidies and/or penalties are some of the considerations to combine these two scenarios. Given future novel sustainable alternatives to livestock animal protein, it may become reasonable to move towards an added general premium price on ‘protein from livestock animals’ to the benefit of promoting higher incomes to farmers at the same time as covering the extra costs of, politically enforced, welfare of livestock animals in sustainable production systems. © 2020 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.     

Toughness of HDPE/CaCO3 microcomposites prepared from masterbatch by melt blend method

In this study, a series of high‐density polyethylene and micro/nanocalcium carbonate polymer composites (HDPE/CaCO₃ nanocomposites) were prepared via melt blend technique using a twin screw extruder. Nanocomposite samples were prepared via injection molding for further testing. The effect of % loading of CaCO₃ on mechanical and fracture toughness of these composites has been investigated in details. The effect of precrack length variation on the fracture toughness of the composite samples was evaluated, and the morphology of the fractured samples was also observed using scanning electron microscopy (SEM). It was found that increasing the % of CaCO₃ and precrack length decreased the fracture toughness. Fracture surface examination by SEM indicated that the diminished fracture properties in the composites were caused by the aglomerization of CaCO₃ particles which acted as stress concentrators. A finite element analysis using ANSYS was also carried out to understand the effect of agglomeration size, interaction between the particles and crack tip length on the fracture properties of these composites. Finally, a schematic presentation of the envisioned fracture processes was proposed. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011