Tomography of the Reionization Epoch with Multifrequency CMB Observations

We study the constraints that future multifrequency Cosmic Microwave Background (CMB) experiments will be able to set on the metal enrichment history of the Inter Galactic Medium at the epoch of reionisation. We forecast the signal to noise ratio for the detection of the signal introduced in the CMB by resonant scattering off metals at the end of the Dark Ages. We take into account systematics associated to inter-channel calibration, PSF reconstruction errors and innacurate foreground removal. We develop an algorithm to optimally extract the signal generated by metals during reionisation and to remove accurately the contamination due to the thermal Sunyaev-Zel'dovich effect. Although demanding levels of foreground characterisation and control of systematics are required, they are very distinct from those encountered in HI-21cm studies and CMB polarization, and this fact encourages the study of resonant scattering off metals as an alternative way of conducting tomography of the reionisation epoch. An ACT-like experiment with optimistic assumtions on systematic effects, and looking at clean regions of the sky, can detect changes of 3%-12% (95% c.l.) of the OIII abundance (with respect its solar value) in the redshift range $z\in$ [12,22], for reionization redshift $z_{\rm re}>10$. However, for $z_{\rm re} <10$, it can only set upper limits on NII abundance increments of $\sim$ 60% its solar value in the redshift range $z\in$ [5.5,9], (95% c.l.). These constraints assume that inter-channel calibration is accurate down to one part in $10^{4}$, which constitutes the most critical technical requirement of this method, but still achievable with current technology.Comment: 10 pages, 2 figures, submitted to Astrophysical Journal. Comments are welcom

Creating sustainable communities: conceptualising an interactive toolkit for skills enhancement

The UK policy framework for the development of sustainable communities, dating from the late 1990’s, has involved substantial changes in the working practices of urban development practitioners. The achievement of sustainable outcomes requires a range of professions, organisations, groups and individuals to work towards shared goals. Thus an emphasis on multi-agency and participatory working has become an integral component of the development of sustainable communities. Initial slow progress gave rise to a review of shortfalls in institutional capacity, and deficits in the generic skills required to enable effective multi-agency working were revealed. The policy response to these perceived deficits included initiatives to provide targeted information and training resources – at both a national and regional level – to urban development professionals and communities. This paper discusses research conducted at a regional level to develop a set of on-line resources focussed on the enhancement of generic skills. The research has addressed a wide range of conceptual and practical difficulties: the nature of generic skills; the capacity of online learning to address contextual skills; and the difficulties of integrating on-line learning into everyday working practices. The paper reviews this conceptual framework and its contribution to the design of the on-line skills resource

Robotic navigation algorithm with machine vision

In the field of robotics, it is essential to know the work area in which the agent is going to develop, for that reason, different methods of mapping and spatial location have been developed for different applications. In this article, a machine vision algorithm is proposed, which is responsible for identifying objects of interest within a work area and determining the polar coordinates to which they are related to the observer, applicable either with a fixed camera or in a mobile agent such as the one presented in this document. The developed algorithm was evaluated in two situations, determining the position of six objects in total around the mobile agent. These results were compared with the real position of each of the objects, reaching a high level of accuracy with an average error of 1.3271% in the distance and 2.8998% in the angle

Can windcatcher's natural ventilation beat the chill? A view from heat loss and thermal discomfort

Windcatchers provide effective low-energy ventilation and summer passive cooling in temperate climates. However, their use in winter is limited due to significant ventilation heat loss and potential discomfort. Limited research has been conducted on quantifying windcatcher heat loss in cold climates, particularly through field studies. This study aims to evaluate the applicability of windcatchers in low-temperature conditions, with a focus on ventilation heat loss and thermal discomfort. Field experiments were conducted in Nottingham, UK, during an icy period. A 3D-printed prototype windcatcher and a test room were built and tested in such weather conditions. A Computational Fluid Dynamics (CFD) model validated against the field experimental data was employed to investigate the windcatcher's performance in a typical UK primary school classroom. The field experimental results indicate that the indoor airflow patterns are dynamic and continuously change with varying external wind conditions. Using static boundary conditions for ventilation analysis is inadequate, as it may lead to inaccurate predictions due to observed fluctuations and irregular airflow patterns. CFD modelling revealed significant over-ventilation in the classroom at external wind speeds of 3 m/s, despite being previously deemed as “satisfactory”, “adequate”, or “sufficient” ventilation. At wind speeds of 3 m/s or higher, the over-ventilation can cause a minimum 941.4 W heat loss, adding 4.7 kWh heating load and £1.6 electricity cost for a typical-sized single classroom during a 5-h occupied period. The research findings highlighted that control strategies should be introduced to reduce over-ventilation. Integrating heat recovery or thermal storage can enhance winter thermal conditions

Packaging Process Optimization in MultiheadWeighers with Double-Layered Upright and Diagonal Systems

[EN] In multihead weighers, packaging processes seek to find the best combination of passage hoppers whose product content provides a total package weight as close as possible to its (nominal) label weight. The weighing hoppers arranged in these machines dispense the product quantity that each package contains through computer algorithms designed and executed for this purpose. For its part, in the packaging process for double-layered multihead weighers, all hoppers are arranged in two levels. The first layer comprises a group of weighing hoppers, and the second comprises a set of booster hoppers placed uprightly or diagonally to each weighing hopper based on design of the machine. In both processes, the initial machine configuration is the same; however, the hopper selection algorithm works differently. This paper proposes a new packaging process optimization algorithm for double-layer upright and diagonal machines, wherein the hopper subset combined has previously been defined, and the packaging weight is expressed as actual values. As part of its validation, product filling strategies were implemented for weighing hoppers to assess the algorithm in different scenarios. Results from the process performance metrics prove that the new algorithm improves processes by reducing variability. In addition, results reveal that some machine configurations were also able to improve their operation.We express our gratitude for the support from Universidad Simon Bolivar, and Universitat Politecnica de Valencia.Garcia-Jimenez, R.; García-Díaz, JC.; Pulido-Rojano, ADJ. (2021). Packaging Process Optimization in MultiheadWeighers with Double-Layered Upright and Diagonal Systems. Mathematics. 9(9):1-20. https://doi.org/10.3390/math9091039S1209

Evaluación de un modelo de optimización no lineal para el despacho económico de microrredes aisladas

The present research work shows the optimal energy management of an isolated microgrid based on non-conventional renewable energy sources. For which an economic dispatch problem is proposed that seeks to supply the electrical demand at the lowest possible operating cost, based on a mixed integer nonlinear optimization problem. The nonlinearity of the algorithm is presented by including the characteristic equation of the real operation of the generating set in the optimization model. The input data to the economic office such as solar radiation and wind speed were obtained from the NASA platform located on Santa Cruz Island, Galapagos province, Ecuador. In addition, the electricity demand data was obtained from real measurements of the sector. The economic dispatch problem has been determined for 12, 24 and 168 hours respectively, obtaining a proportional energy distribution for each case of 50.40% supplied by the photovoltaic generator, 23.92% by the diesel generator, 17.14% by the battery bank and 5.53% by the wind generator, so the demand was supplied in its entirety, meeting the objective that the generating set does not present intermittencies and obtaining the lowest operating cost of the system.El presente trabajo de investigación muestra la gestión óptima de la energía de una microrred aislada basada en fuentes de energía renovable no convencional. Para lo cual se plantea un problema de despacho económico que busca abastecer la demanda eléctrica al menor costo de operación posible, a partir de un problema de optimización no lineal entero mixto. La no linealidad del algoritmo se presenta al incluir la ecuación característica del funcionamiento real del grupo electrógeno en el modelo de optimización. Los datos de entrada al despacho económico como radiación solar y velocidad del viento fueron obtenidos de la plataforma de la NASA situada sobre la isla Santa Cruz, provincia de Galápagos, Ecuador. Además, los datos de la demanda eléctrica fueron obtenidos de mediciones reales del sector. El problema de despacho económico se ha resultado para 12, 24 y 168 horas respectivamente, obteniendo una distribución energética proporcional para cada caso del 50.40 % suministrada por el generador fotovoltaico, 23.92 % por el generador diésel, 17.14 % por el banco de baterías y 5.53 % por el generador eólico, por lo que la demanda fue abastecida en su totalidad cumpliendo con el objetivo de que el grupo electrógeno no presente intermitencias y obteniendo el menor costo de operación del sistema

Bubble formation regimes in forced co-axial air-water jets

We report a detailed experimental characterization of the periodic bubbling regimes that take place in an axisymmetric air-water jet when the inner air stream is forced by periodic modulations of the pressure at the upstream air feeding chamber. When the forcing pressure amplitude is larger than a critical value, the bubble formation process is controlled by the forcing frequency, leading to the formation of nearly monodisperse bubbles whose volume is reduced as the forcing rate increases. We reveal the existence of two different breakup modes, M1 and M2, under effective forcing conditions. The bubble formation in mode M1 resembles the natural bubbling process, featuring an initial radial expansion of an air ligament attached to the injector, whose initial length is smaller than the wavelength of a small interfacial perturbation induced by the oscillating air flow rate. The expansion stage is followed by a ligament collapse stage, which begins with the formation of an incipient neck that propagates downstream while collapsing radially inwards, leading to the pinch-off of a new bubble. These two stages take place faster than in the unforced case due to the air flow modulation induced by the forcing system. The breakup mode M2 takes place with an intact ligament longer than one disturbance wavelength, whereby the interface already presents a local necking region at pinch-off, and leads to the formation of bubbles from the tip of an elongated air filament without an expansion stage.This work has been supported by the Spanish MINECO and European Funds under projects DPI2017-88201-C3-2-R and DPI2017- 88201-C3-3-R . JRR wants to acknowledge the Spanish MINECO for the financial support provided by the Fellowship BES-2015-07132

Neutrino Halos in Clusters of Galaxies and their Weak Lensing Signature

We study whether non-linear gravitational effects of relic neutrinos on the development of clustering and large-scale structure may be observable by weak gravitational lensing. We compute the density profile of relic massive neutrinos in a spherical model of a cluster of galaxies, for several neutrino mass schemes and cluster masses. Relic neutrinos add a small perturbation to the mass profile, making it more extended in the outer parts. In principle, this non-linear neutrino perturbation is detectable in an all-sky weak lensing survey such as EUCLID by averaging the shear profile of a large fraction of the visible massive clusters in the universe, or from its signature in the general weak lensing power spectrum or its cross-spectrum with galaxies. However, correctly modeling the distribution of mass in baryons and cold dark matter and suppressing any systematic errors to the accuracy required for detecting this neutrino perturbation is severely challenging.Comment: 13 pages, 11 figures. Submitted to JCA

Sensitivity of evapotranspiration components in remote sensing-based models

Accurately estimating evapotranspiration (ET) at large spatial scales is essential to our understanding of land-atmosphere coupling and the surface balance of water and energy. Comparisons between remote sensing-based ET models are difficult due to diversity in model formulation, parametrization and data requirements. The constituent components of ET have been shown to deviate substantially among models as well as between models and field estimates. This study analyses the sensitivity of three global ET remote sensing models in an attempt to isolate the error associated with forcing uncertainty and reveal the underlying variables driving the model components. We examine the transpiration, soil evaporation, interception and total ET estimates of the Penman-Monteith model from the Moderate Resolution Imaging Spectroradiometer (PM-MOD), the Priestley-Taylor Jet Propulsion Laboratory model (PT-JPL) and the Global Land Evaporation Amsterdam Model (GLEAM) at 42 sites where ET components have been measured using field techniques. We analyse the sensitivity of the models based on the uncertainty of the input variables and as a function of the raw value of the variables themselves. We find that, at 10% added uncertainty levels, the total ET estimates from PT-JPL, PM-MOD and GLEAM are most sensitive to Normalized Difference Vegetation Index (NDVI) (%RMSD = 100.0), relative humidity (%RMSD = 122.3) and net radiation (%RMSD = 7.49), respectively. Consistently, systemic bias introduced by forcing uncertainty in the component estimates is mitigated when components are aggregated to a total ET estimate. These results suggest that slight changes to forcing may result in outsized variation in ET partitioning and relatively smaller changes to the total ET estimates. Our results help to explain why model estimates of total ET perform relatively well despite large inter-model divergence in the individual ET component estimates