Local Operating Conditions Research Articles

Understanding access to sexual and reproductive health in general practice using an adapted Candidacy Framework; a systematic review and qualitative evidence synthesis.

Background General practice has a key role in reducing inequity in access to sexual and reproductive health (SRH). Unplanned pregnancy, abortion and STIs are increasing and disproportionately affects deprived communities and ethnic minority groups. The candidacy framework offers a practical, theoretical framework for understanding the complex interactional processes of access to SRH in general practice. Aim To use the candidacy framework to explore access of SRH in general practice. The seven interaction stages include, identification of need, navigation of services, permeability of services, appearing and asserting need, adjudication by healthcare professional, offers or resistance of offer and the local operating conditions or local production of candidacy. Design and setting This study involved a systematic review with qualitative evidence synthesis using a framework approach. Methods A systematic search of MEDLINE, EMBASE, PUBMED, and the Web of Science was conducted to identify primary qualitative research studies exploring access to SRH in general practice from practitioner, public, and patient perspectives in countries with universal healthcare. The candidacy framework was used to synthesise the findings. Results Analysis of 42 studies revealed the impact of stigma, shame, and embarrassment among individuals, communities, and healthcare practitioners. Findings showed limited inclusion of demographics such as ethnicity and socio-economic status. Barriers to access were more evident for those from lower socio-economic communities, ethnic minorities and LGBTQ+. There are multiple barriers, which include the behaviours of healthcare professionals who have a crucial role in recognising an individual's SRH need. Conclusions General practice offers a cradle-to-grave healthcare service, which should have SRH as a priority area of provision. Further understanding is needed of the impact of historic harms by medicine and healthcare on racialised individuals and gender minorities.

Advanced Methodology for Simulating Local Operating Conditions in Large Fuel Cells Based on a Spatially Averaged Pseudo-3D Model

To address the performance and lifetime limitations of Proton Exchange Membrane Fuel Cells, it is essential to have a comprehensive understanding of the operating heterogeneities at the cell scale, requiring the test of a wide range of operating conditions. To avoid experimental constraints, numerical simulations seem to be the most viable option. Hence, there is a need for time-efficient and accurate cell-scale models. In this intention, previous works led to the development and the experimental calibration of a pseudo-3D model of a full-size cell in a stack. To further reduce the computation time, a new spatially averaged, multi-physics, single-phase, non-isothermal, steady state pseudo-3D model is developed and calibrated with the results of the preceding model. Particularly, it captures the influence of the coolant on temperature and water mappings in the cell. Moreover, a new methodology is proposed to calibrate the electrochemical cell voltage law for new membrane-electrode assemblies. The emulation of the local operation conditions in large active surface area is realized with a small differential cell, avoiding the testing of large single cells or stacks. Subsequently, simulations are conducted to investigate the impact of the coolant temperature gradient, coolant outlet temperature and gas relative humidity.

Experimental investigation on the effect of channel geometry on performance heterogeneity in hydrogen PEM fuel cell

Straight parallel graphite-based flow fields are experimentally assessed to evaluate the effect of geometrical parameters on the performance of polymer electrolyte membrane fuel cell. A 1+1D fuel cell model is exploited to evaluate the local operating conditions occurring along various positions of the flow field channel for different load requirements. The estimated operating conditions are implemented in a zero-gradient hardware to perform a broad experimental campaign, conducting tests under controlled and uniform operating conditions. The achieved experimental results depict the impact of the flow field geometry along different positions of the flow field channel under real operating conditions, identifying the individual contributions of the geometric parameters on water transport, oxygen transport and electrical resistance. The proposed methodology provides detailed information on the local operation of a large-area bipolar plate using a small-area sample, demonstrating the effect of rib and channel geometrical parameters on real-world operation of a PEMFC.

TRANSFORMING WASTE MANAGEMENT: EVALUATION OF A FIXED BED BATCH-TYPE PYROLYSIS PLANT UTILIZING SCRAP TIRES IN BANGLADESH

This study assesses the efficacy of a fixed bed batch-type pyrolysis plant utilizing scrap tires as feedstock for waste management in Bangladesh. Pyrolysis presents a promising approach to address the mounting challenge of tire disposal by converting scrap tires into valuable products such as fuel oil, carbon black, and steel wire. The research encompasses the design, fabrication, and performance evaluation of the pyrolysis plant under local operational conditions. Through comprehensive testing and analysis, key performance indicators including pyrolysis efficiency, product yield, and environmental impact are assessed. The findings offer insights into the feasibility and sustainability of pyrolysis-based waste management solutions in Bangladesh, with implications for addressing broader environmental and energy challenges.

Impact of Clamping Force Distribution on Loss Processes in a Segmented PEMFC

The operation of large-scale polymer electrolyte membrane fuel cells (PEMFC) inevitably leads to significant spatial gradients along the gas channels. Depending on the local operating conditions, the physicochemical processes and thus also the resistances in the cell vary, which in turn determine the local performance. In addition, design parameters such as the spatial clamping force distribution have a significant influence on the ohmic contact resistance and the compression of the porous layers and thus the diffusion resistance. Thereby, the influences of these factors on the corresponding resistances are opposite to each other, resulting in conflicting objectives.To enable an optimization of the operating strategy and the component design, a quantification of the local resistances and their dependencies is essential.This requires a measurement setup that allows the precise adjustment of the operating conditions and contact pressure along the gas channel, as well as a measurement and analysis method that identifies and quantifies the locally occurring processes.For this purpose, we are applying electrochemical impedance spectroscopy (EIS) on a segmented cell. In this cell the local clamping force is individually adjusted and continuously measured for each segment enabling measurements at constant clamping force as well as selectable clamping force distributions. The local performance limiting loss processes within the cell are separated by the distribution of relaxation times (DRT) and quantified by a physico-chemical meaningful transmission line model (TLM) as a function of local operating conditions and clamping force [1, 2, 3].In this contribution an experimental analysis of the ohmic, charge transfer and diffusion resistances will be presented. The impact of contact pressure distribution and operating conditions on resistances and their distribution along the gas channels will be discussed. Furthermore, it is demonstrated how the performance can be optimized by adjusting the contact pressure distribution along the gas channel.1. H. Schichlein et al., J. Appl. Electrochem. 32, pp. 875-882 (2002).2. E. Ivers-Tiffée et al., J. Ceram. Soc. Japan 125, pp. 193-201 (2017).3. M. Heinzmann et al., J. Power Sources 558, 232540 (2023).

Modelling Analysis of MEA Dynamic Operation Under Real-World Automotive Driving Cycle

In last years, Proton Exchange Membrane Fuel Cells (PEMFC) have received an increasing interest as a candidate for light and heavy-duty vehicle application1. To guarantee an efficient and durable operation of PEMFC, the understanding of local conditions, experienced by MEA, during dynamic operation is highly important. Effective numerical modelling can help to gain insights on the local heterogeneity linked to water and thermal management of the cell.A 1 + 1D multiphase dynamic non isothermal PEMFC model, implemented into MATLAB Simulink environment, was used to investigate experimental data obtained on a segmented cell hardware 2. Particular attention was paid to properly model the mass transport and kinetic related phenomena in catalyst layer(CL), as the local oxygen transport resistance through the ionomer thin film3 and the platinum oxide formation/reduction reaction, and their mutual interaction. Exploiting experimental data, obtained from tests on the segmented cell hardware, it was possible to give a robust validation to the 1+1D model, both at global and local level, thanks to the spatially-resolved information available. By simulating real-world driving cycle (DLC) protocol, developed within the ID-FAST project4, drying-up periods of ionomer contained in catalyst layers and in membrane, as well as flooding periods of porous layers and channels, were identified and analyzed during low-load and high-load operation.The performance model was coupled with a catalyst durability model, such to investigate the effect of ageing on dynamic performance of PEMFC. An innovative semi-empirical electrochemical surface area (ECSA) loss model was developed, based on the platinum dissolution mechanism, and validated initially on accelerated stress tests on different operating conditions5. The simulated load profile and local operating conditions in CLs were processed by a proper algorithm, to convert a driving cycle into a combination of elementary steps and to associate a loss factor for the ECSA to each of the identified elements, thus to estimate the retained local and global ECSA. Exploiting experimental database made up of 1000 operating hours performing ID-FAST DLC, the effect of local operating conditions on PEMFC degradation and performance was furtherly comprehended, focusing mainly on the effect of reactant humidification. The developed model framework succeeded in estimating performance loss during driving cycle operation, as visible in Figure 1(a-b). Simulated and experimental ECSA decay over time is shown in Figure 1(c), demonstrating good model prediction capability. The obtained results showed the potentiality of the model to capture complex two-phase and non-isothermal transport phenomena both in the along channel and through-MEA direction, consistently with a large set of experimental data.Experimental data on single cell were collected under ID-FAST project (Grant Agreement No 779565, Joint Undertaking, EU Horizon 2020).References D. A. Cullen et al., Nat. Energy, 6, 462–474 (2021) https://www.nature.com/articles/s41560-021-00775-z.E. Colombo, A. Baricci, A. Bisello, L. Guetaz, and A. Casalegno, J. Power Sources, 553, 232246 (2023) https://doi.org/10.1016/j.jpowsour.2022.232246.T. Suzuki, H. Yamada, K. Tsusaka, and Y. Morimoto, J. Electrochem. Soc., 165, F166–F172 (2018) https://iopscience.iop.org/article/10.1149/2.0471803jes.F. Wilhelm et al., ID-FAST -D4.3 – Analysis of coupling between mechanisms and definition of combined ASTs, p. 49, (2021) https://www.id-fast.eu/uploads/media/ID-FAST_D4-3_Analysis_of_coupling_between_mechanisms_and_definition_of_combined_ASTs_OK.pdf.A. Kneer and N. Wagner, J. Electrochem. Soc., 166, F120–F127 (2019) https://iopscience.iop.org/article/10.1149/2.0641902jes. Figure 1

Taking Advantage of the Operating Heterogeneities in PEMFC: Numerical Study with a Pseudo-3D Model

A Proton Exchange Membrane Fuel Cell (PEMFC) is an open system. Its operation is therefore inherently heterogeneous. Indeed, in a cell, electrochemical reactions do not take place homogeneously on the active surface area. It has already been pointed out that operating heterogeneities over a large cell active area can cause a decrease of performance and durability. In fact, studies to date have focused on the relation between operating heterogeneities and local degradation on the active surface area for a small selection of operating conditions.The objective of our study is to find a way to control the current, temperature and water distributions by adjusting the operating conditions to, hopefully, optimize performance and improve durability. In order to define those control strategies, a better understanding of the heterogeneities for a wide range of operating conditions is necessary. To that end, a first numerical approach seems to be the most appropriate.This numerical study is based on a pseudo-3D multi-physics and single-phase model of a large cell, developed on COMSOL Multiphysics®. One novelty of our study, from a methodological point of view, is the calibration of the model. Instead of calibrating the model with the electrochemical response of a large cell for some chosen operating conditions as per usual, it has been calibrated with the electrochemical response of a small cell (1.8 cm²), called differential cell, emulating local operating conditions on a larger cell. Three areas of the large cell were emulated for different operating conditions: inlet, middle and outlet. Once calibrated, the pseudo-3D model was used to calculate the distributions for 108 operating conditions, which were chosen from a full factorial design of experiment defined according to the automobile application of PEMFC. The statistical analysis of these simulation results will give the influence of operating conditions (gases pressure, the magnitude and orientation of the thermal gradient of the cooling fluid, gases temperature and relative humidity) on the current density, temperature and water distributions on the active surface area. These results will later be useful for the design of strategies for controlling heterogeneities, which will be finally tested on PEM stack. Figure 1

AirQo sensor kit: A particulate matter air quality sensing kit custom designed for low-resource settings

Air pollution remains a major public health risk. People living in urban spaces are among those most affected by exposure to unhealthy levels of air pollution. However, many urban spaces especially in low- and middle-income countries lack high resolution and long-term data on the state of air quality. Without high resolution air quality data on the different spaces in a city, citizens and authorities are unable to quantify the challenge and act. This is in part attributed to the high cost of air quality monitoring equipment that are expensive to set up, maintain and not designed for local operating conditions that characterise environments in such contexts. In this paper, we describe AirQo sensor kit, a low-cost sensing hardware system designed for and custom made to work in low-resource settings and outdoor urban environments. We describe the design of the air quality sensing device, 3D-printed enclosure, installation-mount, fabrication and deployment configurations. We demonstrate that the low-cost sensing hardware provides a complete solution comparable to the traditional monitoring system and inspires action to tackle air pollution issues. The sensor kit presented in this paper has been widely deployed in cities in Eastern, Western and Central African countries.

Activity of Ammonium-Oxidizing Bacteria—An Essential Parameter for Model-Based N2O Mitigation Control Strategies for Biofilms

The reduction in N2O emissions is an important task in the control of wastewater treatment plants. Since local operating conditions, especially inside biofilms, are usually not known, models are an important tool in the development and implementation of control strategies. For a pilot-scale nitrifying biofilm reactor and an SBR, different operational strategies to reduce autotrophic nitrous oxide (N2O) formation were developed and tested by applying a combination of modeling and measurement. Both approaches highlighted the relevance of addressing the actual AOB activity as a sensitive control variable. The investigated strategies, therefore, focused on decreasing the AOB-related NH4 conversion rate, as autotrophic N2O formation is directly linked to AOB activity. The results showed that the biofilm system was more advantageous compared with suspended sludge systems. A higher AOB content resulted in a decrease in AOB activity, leading to fewer N2O emissions at the same reactor performance. The highest reduction in autotrophic N2O formation (SBR: 25%; Biofilm: 27%) was obtained by maximizing the aerated time per day and minimizing the number of aeration cycles (the suppression of nitrite-oxidizing bacteria still needed to be ensured). A higher biofilm thickness or a higher sludge mass in the SBR, however, did not have a noteworthy positive effect since no additional biomass could be kept in the system in the long term due to limited substrate availability. Besides nitritation, denitrification was also identified as a relevant source of N2O in both systems (biofilm: main source) due to the inhibition of N2O reduction by nitrous acid (elevated nitrite concentrations in combination with pH values < 7).

Advancements on Optimization Algorithms Applied to Wave Energy Assessment: An Overview on Wave Climate and Energy Resource

The wave energy sector has not reached a sufficient level of maturity for commercial competitiveness, thus requiring further efforts towards optimizing existing technologies and making wave energy a viable alternative to bolster energy mixes. Usually, these efforts are supported by physical and numerical modelling of complex physical phenomena, which require extensive resources and time to obtain reliable, yet limited results. To complement these approaches, artificial-intelligence-based techniques (AI) are gaining increasing interest, given their computational speed and capability of searching large solution spaces and/or identifying key study patterns. Under this scope, this paper presents a comprehensive review on the use of computational systems and AI-based techniques to wave climate and energy resource studies. The paper reviews different optimization methods, analyses their application to extreme events and examines their use in wave propagation and forecasting, which are pivotal towards ensuring survivability and assessing the local wave operational conditions, respectively. The use of AI has shown promising results in improving the efficiency, accuracy and reliability of wave predictions and can enable a more thorough and automated sweep of alternative design solutions, within a more reasonable timeframe and at a lower computational cost. However, the particularities of each case study still limit generalizations, although some application patterns have been identified—such as the frequent use of neural networks.

Effects of the size and cost reduction on a discounted payback period and levelized cost of energy of a zero-export photovoltaic system with green hydrogen storage

Zero-export photovoltaic systems are an option to transition to Smart Grids. They decarbonize the sector without affecting third parties. This paper proposes the analysis of a zero-export PVS with a green hydrogen generation and storage system. This configuration is feasible to apply by any self-generation entity; it allows the user to increase their resilience and independence from the electrical network. The technical issue is simplified because the grid supplies no power. The main challenge is finding an economic balance between the savings in electricity billing, proportional to the local electricity rate, and the complete system's investment, operation, and maintenance expenses. This manuscript presents the effects of the power sizing on the efficacy of economic savings in billing (ηSaving) and the effects of the cost reduction on the levelized cost of energy (LCOE) and a discounted payback period (DPP) based on net present value. In addition, this study established an analytical relationship between LCOE and DPP. The designed methodology proposes to size and selects systems to use and store green hydrogen from the zero-export photovoltaic system. The input data in the case study are obtained experimentally from the Autonomous University of the State of Quintana Roo, located on Mexico's southern border. The maximum power of the load is LPmax = 500 kW, and the average power is LPmean = 250 kW; the tariff of the electricity network operator has hourly conditions for a medium voltage demand. A suggested semi-empirical equation allows for determining the efficiency of the fuel cell and electrolyzer as a function of the local operating conditions and the nominal power of the components. The analytical strategy, the energy balance equations, and the identity functions that delimit the operating conditions are detailed to be generalized to other case studies. The results are obtained by a computer code programmed in C++ language. According to our boundary conditions, results show no significant savings generated by the installation of the hydrogen system when the zero-export photovoltaic system Power ≤ LPmax and DPP ≤ 20 years is possible only with LCOE ≤ 0.1 $/kWh. Specifically for the Mexico University case study, zero-export photovoltaic system cost must be less than 310 $/kW, fuel cell cost less than 395 $/kW, and electrolyzer cost less than 460 $/kW.

Predictability and interrelations of spectral indicators for PV performance in multiple latitudes and climates

When PV is installed in the field, the module technologies are rated according to their output energy yield under local operating conditions rather than at standard test conditions (STC), where the spectrum is set to AM1.5G. Care must be taken as this standard is not optimal for all latitudes and the solar spectral distribution variations are one primary influencing factor on PV performance. In addition, obtaining an accurate estimate of the spectral effects on PV performance, as set out in standard procedures, is hampered by the cost of gathering the inputs and the large amount of spectral data required for such a calculation. In this work, based on measured spectral irradiance data from nine sites of different latitudes and climates, we first show a characteristic trend in the spectral distribution over the year concerning the location latitude. The closer a site is to the equator, the more blue-rich the solar spectrum is and the fewer seasonal spectral variations it will contain. Then, we calculate and correlate the most popular metrics (device-independent and device-dependent) used to describe the influence of solar spectra on PV performance. In particular, the monthly irradiance-weighted Spectral Mismatch Factor for different PV technologies and Average Photon Energy show a global linear correlation for data from these nine sites. We use this global linear relationship to propose PV technology-dependent equations that predict annual and monthly spectral gains/losses within a prediction half-interval of up to ± 1.66% by only inserting the monthly or annual irradiance-weighted Average Photon Energy potentially for any site. Reducing the required spectral data sets for performance estimation through our methodology facilitates a more accessible and less costly communication of databases than complete spectral data sets. Finally, using this spectral data, we demonstrate statistically that the Spectral Mismatch Factor and Integrated Useful Fraction Ratio can be replaced by alternative spectral metrics, which require only averaged spectra and, thus, reduce the computational effort to estimate the above indicators.

Performance of bifacial PV modules under different operating conditions in the State of Minas Gerais, Brazil

Brazil's cumulative photovoltaic (PV) installations have now surpassed 32 GWp. The fastest growing and most prevalent PV technology is the bifacial photovoltaic module, which is now being incorporated in more than 2/3 of new power plants. These modules collect solar radiation on both front and rear sides, providing gains in electricity production compared to traditional monofacial modules. The market acceptance and quality control of this technology requires standard methods to accurately determine the nominal power of the bifacial modules. But the specification of energy production from the bifacial backside is complicated due to critical factors that include the albedo, the separation, height, and positioning of the modules, the shading of the rear surface, and the specific geographic and climate conditions. This paper addresses these issues in determining the performance of bifacial PV modules in the tropical conditions of the State of Minas Gerais, Brazil. Specifically, the bifacial gain for modules and systems is evaluated, assessing the effects of albedo, site maintenance, climate/environmental conditions, thermal behavior, and back-surface shading. The special cases of tracking versus non-tracking systems are evaluated showing specific attention needs to the albedo changes and rear module shading constraints. These studies are performed on real power plants having different operating conditions (e.g., tracking, non-tracking, ground cover). The methodology includes I-V characterization of modules and string and thermal imaging/mapping under existing climate and meteorological conditions. Correlations with experimental albedo conditions is a special concern with these studies. These results are further compared to controlled laboratory measurements to establish information needed to better evaluate the developing standard for actual local operating conditions. This case study provides evaluation of the quality of the both the bifacial PV products being used and their installations in the rapidly emerging Brazil PV markets.

Evolution and distribution of the anode overpotential and its oscillations in a polymer electrolyte membrane fuel cell exposed to carbon monoxide

Carbon monoxide (CO) poisoning of polymer electrolyte membrane fuel cells (PEMFCs) remains a challenge for their deployment, and a deeper understanding of the spatiotemporal dynamics involved is needed to develop effective mitigation strategies. In this work, localised reference electrodes were used to measure the anode overpotential at three locations across the active area of a galvanostatically operated cell (0.3 A cm−2) exposed to 100 ppm CO/H2. The anode region closest to the inlet was poisoned more rapidly than the rest of the cell, following a sigmoidal variation, and presented a higher CO coverage. The varying CO concentration, combined with local operating conditions, had a direct impact on the distribution of CO coverage. Additionally, complex self-sustained oscillations of the cell voltage and the anode overpotential were observed and correlated with the rate of CO oxidation in the overall cell. The coexistence of a dominant mean-field coupling area closer to the anode inlet, and a dominant migration coupling region closer to the outlet was identified, consistent with reported modelling predictions for a single straight channel cell. Finally, the cell recovery with pure H2 was shown to be a faster process than the CO adsorption, which follows first-order kinetics and is affected by local conditions.

Study on the operating conditions of centrifuges and their individual separative power in a stage of an isotope separation cascade

Since the ideal cascade theory, several mathematical models have been developed to improve the understanding of isotopic separation cascades. Despite numerous advances in modeling multicomponent and transient cascades, there has not yet been a model that takes into account the individual centrifuges' operating conditions and separative power.This study analyses how the number of centrifuges in a stage relates to the pressure drop in the pipes, which in turn affects the centrifuges’ separative power. It estimates the local operating conditions, checks them against the mass balances in the pipes and, then, calculates the separative performance of the centrifuges.Results were presented for a stage with 40 generic centrifuges. There was a sharp pressure drop in the extremities of the stage that caused roughly 15% and 30% pressure loss in the feed and product pipes, respectively, which caused the last centrifuge to yield a separative power 14% lower than the first one.

Are subsidies for thermally-driven solar-assisted cooling systems consistent? A critical investigation for Southern Italy

The growing availability of low-cost electricity-driven air-conditioning systems has determined a huge increase in the electricity demand for space cooling, especially in warm and hot climates. In this framework, thermally-driven solar-assisted cooling systems are a very interesting alternative, since they are mainly fed by converting the largely available solar radiation into thermal energy: however, their economic convenience is still questionable. For this reason, many EU states have introduced suitable subsidies: in Italy, the so-called “Conto Termico” proposes cash-back incentives proportional to the thermal energy delivered by the solar field.This study investigates the suitability and consistency of these subsidies, by considering a case study including a thermally-driven solar-assisted absorption chiller that cools down an office building located in Palermo (Southern Italy). The study looks into the sizing of the system and evaluates its techno-economic feasibility by considering the incentives introduced by the Italian “Conto Termico”. The results highlight that the proposed solar-assisted absorption cooling system can reduce primary energy demand and CO2 emissions by around 75% if compared to a conventional electric chiller, under a reasonable sizing of the solar section. The subsidies are proportional to the thermal energy delivered by the solar collectors, and thus tend to favour the adoption of high collecting surfaces: for instance, installing 2 m2 of evacuated tube solar collectors per unit cooling capacity ensures relatively low payback periods of 15 years or even less. However, the energy performance of the system does not improve accordingly with higher collecting surfaces, since a non-negligible rate of delivered thermal energy is wasted, as witnessed by the decreasing seasonal COP. Moreover, Flat Plate Collectors are improperly penalized, and the real local operating conditions are not considered in the calculation. This suggests that the rationale leading Italian subsidies are not consistent, and needs being improved.

Influence of Wood Fly Ash on Concrete Properties through Filling Effect Mechanism.

This paper presents the results of an experimental study aimed at determining the influence of wood fly ash (WFA) from three Croatian power plants on the properties of concrete. First, the chemical and physical properties of WFA’s were determined. It was found that these properties are highly influenced by combustion technology, the type and parts of wood used as fuel, and the local operating conditions. Subsequently, workability, heat of hydration, stiffness development, 28-day compressive strength, apparent porosity, and capillary absorption were determined on concrete mixes prepared with WFA as cement replacement from 5–45% by weight. Cement replacement up to 15% with the finest WFA accelerated hydration, stiffness development, and increased compressive strength of concrete up to 18%, while replacement with coarser WFA’s led to a decrease in compressive strength of up to 5% and had more gradual heat liberation. The dominant effect that could explain these findings is attributed to the filler and filling effect mechanisms. At the same time replacement content of up to 45% had very little effect on capillary absorption and could give concrete with sufficiently high compressive strength to be suitable for construction purposes.

Polyol-Made Spinel Ferrite Nanoparticles—Local Structure and Operating Conditions: NiFe2O4 as a Case Study

We report the effect of a polyol-mediated annealing on nickel ferrite nanoparticles. By combining X-ray fluorescence spectroscopy, X-ray diffraction, and 57Fe Mössbauer spectrometry, we showed that whereas the as-prepared nanoparticles (NFO) are stoichiometric, the annealed ones (a-NFO) are not, since Ni0-based crystals precipitate. Nickel depletion from the spinel lattice and reduction in the polyol solvent are accompanied with an important cation migration. Indeed, thanks to Mössbauer hyperfine structure analysis, we evidenced that the cation distribution in NFO departs from the thermodynamically stable inverse spinel structure with a concentration of tetrahedrally coordinated Ni2+ of 20 wt-% (A sites). After annealing, and nickel demixing, originated very probably from the A sites of NFO lattice, the spinel phase accommodates with cation and anion vacancies, leading to the (Fe3+0.84□0.16)A[Ni2+0.80Fe3+1.16□0.04]BO4-0.20 formula, meaning that the applied polyol-mediated treatment is not so trivial.

Modeling Nickel Microstructural Evolution in Ni-YSZ Electrodes Using a Mathematical Morphology Approach

Microstructural evolution of Nickel in Ni-YSZ fuel electrodes is one of the main limiting degradation mechanisms in solid oxide cells [1]. The redistribution of Nickel is ascribed to its high mobility and low wettability with YSZ, related to interfacial surface tensions. Practically, the degradation manifests as the agglomeration of Ni, potentially accompanied by its migration, mainly reported in electrolysis mode.Extensive efforts have been made to understand Ni agglomeration and relocation. In this frame, advanced imaging techniques have been employed to characterize the microstructure of electrodes after aging in a wide range of conditions. In order to support these observations and gain fundamental insights, a number of computer simulations methods such as: multistate kinetic Potts-Monte Carlo models, cellular automata, phase field, and topological boundary dynamics have been successfully employed in modelling grain growth and recrystallization phenomena. Nevertheless, questions still remain on the exact underlying mechanisms of Ni migration.In the shadow of this lack of clear understanding, a morphological modelling approach aiming at mimicking Ni depletion based on the most fundamental definition of chemical potential and surface curvature minimization would be very helpful to guide researchers into gaining clearer insights of this phenomenon. Moreover, the morphological simulations are very fast compared to the physically based models. Therefore, they can offer the possibility to emulate large database of numerical microstructures in order to study the impact of Ni evolution on the microstructural properties [2].The current work falls within this framework and aims at modelling the two main Ni degradation phenomena, namely coarsening and migration. For this purpose, a novel model based on morphological operations from mathematical morphology [3] has been developed and adapted to the Ni-YSZ specificities. The considered driving force for Ni evolution is the minimization of its surface curvature, and implicitly its chemical potential, which strongly depends on the local operating conditions. After calibration, the model showed a capability to predict, starting from an initial 3-D microstructure as input data, Ni relocation that was in agreement with that observed in a large dataset of 3-D reconstructions from pristine and aged cells. This helps understanding the associated microstructural evolutions which are linked to the cell Area Specific Resistance (ASR) through an adapted in-house model. This coupling of microstructural and electrochemical models allows giving clearer insights and practical recommendations for the design of fuel electrodes with improved stability and electro-catalytic activity.[1] M. Hubert, J. Laurencin, P. Cloetens, B. Morel, D. Montinaro, F. Lefebvre-Joud, Journal of Power Sources, 397 (2018) 240-251.[2] H. Moussaoui, R.K. Sharma, J. Debayle, Y. Gavet, G. Delette, J. Laurencin, Journal of Power Sources, 412 (2019) 736-748.[3] J. Serra, Image Analysis and Mathematical Morphology: Theoretical Advances, Academic Press, Cornell University (1988). Figure 1

Improving pumpset selection to support intensification of groundwater irrigation in the Eastern Indo-Gangetic Plains

Intensification of groundwater irrigation is central to goals of improving food security and reducing chronic poverty faced by millions of rural households across the eastern Indo-Gangetic Plains (EIGP) of Nepal and parts of eastern India. At present, levels of groundwater use and access in the EIGP lag far behind other areas of South Asia despite abundant available groundwater resources. A key reason for prevailing access constraints is the dependence on diesel pumpsets for accessing groundwater, which are typically unsubsidised and therefore expensive to purchase and operate. To date, efforts to reduce access costs have focused almost exclusively on how to incentivise adoption of alternative electric or solar-powered pumping technologies, which are viewed as being cheaper to operate and less environmentally damaging due to their lower operational carbon emissions. In contrast, there has been little attention paid to identifying opportunities to make existing diesel pump systems more cost effective for farmers to operate in order to support adaptation to climate change and reduce poverty. In this study, we use evidence from 116 detailed in-situ pump tests along with interviews with pumpset dealers, mechanics and farmers in the Nepal Terai to assess how and why fuel efficiency and operational costs of diesel pump irrigation are affected by farmers’ pumpset selection decisions. We show that costs diesel pumpset irrigation can be reduced significantly by supporting and incentivising farmers (e.g., through equipment advisories, improved supply chains for maintenance services and spare parts) to invest in newer low-cost, portable and smaller horsepower pumpset designs that are more effectively matched to local operating conditions in the EIGP than older Indian manufactured engines that have historically been preferred by farmers in the region. Such interventions can help to unlock potential for intensified irrigation water use in the EIGP, contributing to goals of improving agricultural productivity and resilience to climate extremes while also strengthening farmers capacity to invest in emerging low-carbon pumping technologies.