The Use of Recycled and Secondary Aggregates to Achieve A Circular Economy within Geotechnical Engineering

The construction industry’s current dependence on primary aggregates is unsustainable as these are non-renewable resources and the consumption of these materials has a high environmental impact. The global annual production of primary aggregates is estimated to be 50 billion tonnes. In Europe, where 2 billion tonnes of primary aggregates are produced annually, approximately 90% of aggregates are utilised by the construction industry, whilst over 1Gt of waste are sent to landfill; in the UK, 44% of landfilled waste arises from the construction industry. The drive to adopt a circular economy necessitates changes in resource use (including non-renewable aggregates). Recycling wastes, such as aggregates, could help this situation; whilst this concept is not new, it does not appear to have been widely embraced in geotechnical engineering. The aim of this paper is to highlight the benefits of increasing the use of alternative aggregates as this would enable the reserves of primary aggregates to be better maintained and less material would be landfilled—a win-win situation and a contributing step towards developing a truly circular economy.

Prediction of life time of high-power IR laser diode by resolution of its spectrum to single-mode components

The paper proposes a method for predicting the service life of high-power laser diodes used in optoelectronic measuring systems which allow adjusting the thermophysical parameters of the diagnosed flow volume in a certain range of their values. The method based on the analysis of the current dependence of the shape of the line enveloping the laser radiation spectrum after 200 hours of their operation. It is shown that for such an analysis the emission spectrum must be considered as a superposition of the emission spectra of single-mode laser diodes.

Spin–orbit torque driven magnetization switching in W/CoFeB/MgO-based type-Y three terminal magnetic tunnel junctions

We have studied current induced magnetization switching in W/CoFeB/MgO based three terminal magnetic tunnel junctions. The switching driven by spin—orbit torque (SOT) is evaluated in the so-called type-Y structure, in which the magnetic easy-axis of the CoFeB layer lies in the film plane and is orthogonal to the current flow. The effective spin Hall angle estimated from the bias field dependence of critical current (Ic) is ~ 0.07. The field and current dependence of the switching probability are studied. The field and DC current induced switching can be described using a model based on thermally assisted magnetization switching. In contrast, the 50 ns long pulse current dependence of the switching probability shows significant deviation from the model, even if contribution from the field-like torque is included. The deviation is particularly evident when the threshold switching current is larger. These results show that conventional thermally assisted magnetization switching model cannot be used to describe SOT induced switching using short current pulses.

Electron stimulated desorption of vanadyl-groups from vanadium oxide thin films on Ru(0001) probed with STM

Electron injection from an STM tip has been used to desorb individual vanadyl groups from vanadium oxide thin films. The underlying mechanism is analyzed from the bias and current dependence of the desorption rate.

Особенности работы мощных AlInGaN-светодиодов при больших импульсных токах

The current dependences of the output optical power and emission spectral characteristics, including their distribution (mapping) over the emitting surface, of vertical AlInGaN LEDs in a wide range of operating currents up to ~ 70A have been studied. Analysis of the current dependence of the LED optical power and emission spectrum reveals that, starting from a certain level of excitation, it is incorrect to use the value of the average current density when interpreting the ìefficiency dropî. The effect of ìcurrent crowdingî around the contacts becomes the main factor in reducing internal quantum and light extraction efficiency, limiting the energy capabilities of the LED.

Измерение внутреннего квантового выхода излучения InGaN светодиода

A method for measuring of internal quantum efficiency of InGaN-based light-emitting diode is presented. The method consists in measuring the emission power and 3dB frequencies of the LED electroluminescence at two low currents corresponding to the range of growth of the quantum efficiency of the LED, and calculating the value of the internal quantum efficiency according to the corresponding functional dependence. To determine the internal quantum efficiency at other current values, the current dependence of the external quantum efficiency is measured and the coefficient of emission extraction from the structure is calculated from the results of measurements of the internal and external quantum efficiency at a low current. The reliability of the measurement method is confirmed by comparing the measurement results with the results obtained by a known measurement method. The relative difference in measurement results is within 3%.

Enhancing the Economic Viability of Anaerobic Digestion by Exploiting the Whole Biomass of Mango Waste and Its Residues after Digestion

A significant expansion of anaerobic digestion (AD) processes would certainly result in a reduction in the current dependence on fossil fuels. The operational costs, the large amounts of digestate generated and the expenses of dealing with it and the volatility of the fuel indexes represent major environmental and economical challenges to the diffusion of AD. Increasing the bio-products of AD could possibly help in increasing its profitability and limit these challenges. This study investigates the influence of mango starch and seed coats on the biogas produced from mango waste. To overcome the environmental challenges, the digestate was tested and its bio-fertiliser potential proven. The study reached the conclusion that the effect of the starch on the AD biogas of mango waste is low while the effect of the seed coats is quite high. This finding supports further investigations to evaluate the effect of the production of mango starch and seed coat-based products on the profitability of AD. The highest energy balance achieved was 65% at 32 °C, 3.93 g-VS organic concentration and 37% sludge concentration, which yielded a maximum CH4 yield of 62.5%. This finding encourages the application of gate fees for accepting bio-waste, which may help in overcoming its economic challenges.