Evaluation of artificial neural network algorithms for predicting the effect of the urine flow rate on the power performance of microbial fuel cells

© 2020 The Authors Microbial fuel cell (MFC) power performance strongly depends on the biofilm growth, which in turn is affected by the feed flow rate. In this work, an artificial neural network (ANN) approach has been used to simulate the effect of the flow rate on the power output by ceramic MFCs fed with neat human urine. To this aim, three different second-order algorithms were used to train our network and then compared in terms of prediction accuracy and convergence time: Quasi-Newton, Levenberg-Marquardt, and Conjugate Gradient. The results showed that the three training algorithms were able to accurately simulate power production. Amongst all of them, the Levenberg-Marquardt was the one that presented the highest accuracy (R = 95%) and the fastest convergence (7.8 s). These results show that ANNs are useful and reliable tools for predicting energy harvesting from ceramic-MFCs under changeable flow rate conditions, which will facilitate the practical deployment of this technology

Human activities accelerated the degradation of saline seepweed red beaches by amplifying top‐down and bottom‐up forces

Salt marshes dominated by saline seepweed (Suaeda heteroptera) provide important ecosystem services such as sequestering carbon (blue carbon), maintaining healthy fisheries, and protecting shorelines. These salt marshes also constitute stunning red beach landscapes, and the resulting tourism significantly contributes to the local economy. However, land use change and degradation have led to a substantial loss of the red beach area. It remains unclear how human activities influence the top‐down and bottom‐up forces that regulate the distribution and succession of these salt marshes and lead to the degradation of the red beaches. We examined how bottom‐up forces influenced the germination, emergence, and colonization of saline seepweed with field measurements and a laboratory experiment. We also examined whether top‐down forces affected the red beach distribution by conducting a field survey for crab burrows and density, laboratory feeding trials, and waterbird investigations. The higher sediment accretion rate induced by human activities limited the establishment of new red beaches. The construction of tourism facilities and the frequent presence of tourists reduced the density of waterbirds, which in turn increased the density of crabs, intensifying the top‐down forces such as predators and herbivores that drive the degradation of the coastal red beaches. Our results show that sediment accretion and plant–herbivory changes induced by human activities were likely the two primary ecological processes leading to the degradation of the red beaches. Human activities significantly shaped the abundance and distribution of the red beaches by altering both top‐down and bottom‐up ecological processes. Our findings can help us better understand the dynamics of salt marshes and have implications for the management and restoration of coastal wetlands

Precise 210Pb determination with high-efficiency gamma spectrometry for dating of marine sedimentary cores

[EN]In order to establish the chronology of deep-sea sediments from high-resolution 210Pb-dating, the determination of 210Pb and 226Ra activity concentrations needs to be improved. Gamma spectrometry allows determining simultaneously both radionuclides. However, spectrum background is still an issue to obtain high sensitivity. Four deep-sea sediment cores were dated using Mazinger, a gamma spectrometer with high-efficiency and very low-background, and the Constant Rate and Supply model was applied to obtain recent age

Soft skills in the tourism industry of the future: a comparison between Italy and Spain

Purpose – The harmonisation of university degrees at the European level leads us to believe that training needs are addressed in the same way in different countries. However, the inevitable adaptation to the changing environment faced by companies requires a continuous adjustment between training and future needs, according to the sector. The aim of this paper is to compare two leading and culturally similar countries in the tourism sector in order to determine whether training is being provided homogeneously in tourism higher education and whether more specific training is desired to meet the needs of the sector in each country. Design/methodology/approach – This study is part of the European Next Tourism Generation (NTG) Project, the first European partnership to foster a collaborative and productive relationship between the education system and the tourism industry. A mixed research study was conducted with the purpose of development, i.e. with the intention that the results of one method (qualitative) are used to assist the development of the other method (quantitative) and an exploratory sequential design. Both qualitative (29 interviews) and quantitative (509 tourism organisations) methods are used. Findings – For a sector that has undergone significant changes in recent years, the results show the differences between countries around the current level of soft skills of employees, the level they will need to develop in the future and the gaps that those responsible for training future employees in the sector need to focus on for the 2030 horizon. Practical implications – Several recommendations have emerged from this paper: to complement higher education, to achieve a better link between the business world and future workers; to provide much more incentives for international student mobility, which will allow students to develop intercultural soft skills before they enter the world of work, and to propose the creation of a social network to share, communicate and learn about resources specific to the tourism industry. Originality/value – Since the Bologna Plan, higher education institutions have been tasked with preparing students for the world of work and developing the employability of graduates. The link between the professional world (companies) and the educational world (training centres) is a crucial factor in determining students' future skills and needs. When educational programmes respond to the needs of industry, the university can gain a competitive advantage. Therefore, some authors suggest the need for coordination and regular communication between business and training centres, thus improving the competitiveness of companies and reducing the gap that currently exists. In this paper, comparing two culturally similar countries with a recognised trajectory in the tourism sector, we will try to observe this gap and propose interesting options for the future of the sector.The authors wish to emphasise that this work is part of a European project within the framework of the Erasmus + Programme, Next Tourism Generation Alliance 591982-EPP-1-2017-IT-EPPKA2-SSA-B

Assessing the long‐term carbon‐sequestration potential of the semi‐natural salt marshes in the European Wadden Sea

Salt marshes and other blue carbon ecosystems have been increasingly recognized for their carbon (C)‐sink function. Yet, an improved assessment of organic carbon (OC) stocks and C‐sequestration rates is still required to include blue C in C‐crediting programs. Particularly, factors inducing variability in the permanence of sequestration and allochthonous contributions to soil OC stocks require an improved understanding. This study evaluates the potential for long‐term C sequestration in the semi‐natural salt marshes of the European Wadden Sea (WS), conducting deep (1.3 m) down‐core OC‐density assessments in sites with known site histories and accretion records. Because these young marshes have developed from tidal‐flat ecosystems and have undergone rapid succession during the last 80–120 yr, the identification of different ecosystem stages down‐core was crucial to interpret possible changes in OC density. This was conducted based on the down‐core distribution of different foraminiferal taxa and grain sizes. Comparisons of historic and recent accretion rates were conducted to understand possible effects of accretion rate on down‐core changes in OC density. δ13C in OC was used to assess the origin of accumulated OC (autochthonous vs. allochthonous sources). We show that large amounts of short‐term accumulated OC are lost down‐core in the well‐aerated marsh soils of the WS region and thus emphasize the importance of deep sampling to avoid overestimation of C sequestration. Despite steep declines in OC‐density down‐core, minimum values of OC density in the salt‐marsh soils were considerably higher than those of the former tidal‐flat sediments that the marshes were converted from, illustrating the greater C‐sequestration potential of the vegetated ecosystem. However, our data also suggest that marine‐derived allochthonous OC makes up a large fraction of the effectively, long‐term preserved OC stock, whereas atmospheric CO2 removal by marsh vegetation contributes relatively little. The implication of this finding for C‐crediting approaches in blue C ecosystems has yet to be clarified

Las lesiones músculoesqueléticas en instrumentistas de viento madera : prevención mediante la implantación de una asignatura específica en las enseñanzas profesionales de música

Los trastornos músculosesqueléticos se erigen como el tipo de patología más frecuente en músicos. Este tipo de afección osteomuscular viene dada a consecuencia de los movimientos repetitivos de la práctica instrumental, las posturas nocivas o el establecimiento de una técnica inadecuada. Su prevención pasa por el conocimiento anatómico, ergonómico y de las diferentes técnicas o ejercicios que pueden aplicarse con tal fin. En este marco, se pone de manifiesto el desconocimiento existente con respecto al tema entre los profesionales involucrados en el ámbito y, por ende, la necesidad de erradicarlo. Se aboga así por la formación del profesorado, y se propone la instauración de una asignatura en las Enseñanzas Profesionales de Música que trate la prevención de lesiones en músicos, mostrando a través de la siguiente investigación una Programación didáctica experimentada y destinada al alumnado de viento madera.Musculoskeletal disorders stand as the most frequent type of pathology in musicians. This type of osteomuscular affection is given as a consequence of the repetitive movements of the instrumental practice, the harmful postures or the establishment of an inadequate technique. Its prevention goes through an anatomical, ergonomic knowledge and the different techniques or exercises that can be applied for this purpose. In this framework, the existing ignorance regarding the subject among the professionals involved in the field is revealed and, finally, the need to eradicate it. Thus, teacher training is advocated, and the establishment of a subject in the Professional Music Education that deals with the prevention of injuries in musicians is proposed, showing through the following investigation an experimented Didactic Programming intended for woodwing students

Late Holocene climate variability in the southwestern Mediterranean region: an integrated marine and terrestrial geochemical approach

A combination of marine (Alboran Sea cores, ODP 976 and TTR 300 G) and terrestrial (Zoñar Lake, Andalucia, Spain) geochemical proxies provides a high-resolution reconstruction of climate variability and human influence in the southwestern Mediterranean region for the last 4000 years at inter-centennial resolution. Proxies respond to changes in precipitation rather than temperature alone. Our combined terrestrial and marine archive documents a succession of dry and wet periods coherent with the North Atlantic climate signal. A dry period occurred prior to 2.7 cal ka BP – synchronously to the global aridity crisis of the third-millennium BC – and during the Medieval Climate Anomaly (1.4–0.7 cal ka BP). Wetter conditions prevailed from 2.7 to 1.4 cal ka BP. Hydrological signatures during the Little Ice Age are highly variable but consistent with more humidity than the Medieval Climate Anomaly. Additionally, Pb anomalies in sediments at the end of the Bronze Age suggest anthropogenic pollution earlier than the Roman Empire development in the Iberian Peninsula. The Late Holocene climate evolution of the in the study area confirms the see-saw pattern between the eastern and western Mediterranean regions and the higher influence of the North Atlantic dynamics in the western Mediterranean

Influence of seasonal factors in the earned value of construction

[EN] The objectives in each construction process can be multiple. However, the constructions have to be carried out under some restrictions concerning price and terms. They constitute some strategic and interdependent goals. In other words, ¿time is money¿. Several papers support that seasonal effects influence the execution rate of construction. Thus, most of them try to improve the forecasts by evaluating and joining them to the planning, although always measuring their influence indirectly. In this paper, we suggest a methodology to directly measure the influence of the seasonal factors as a whole over the earned value of construction. Additionally, we apply it to a certain case study regarding the subsidised housing of public promotion in the Castilla-La Mancha region (Spain). It is worth mentioning that our results are clarified: we have calculated the average monthly production for each month a year with respect to the annual monthly mean. Moreover, the differences regarding the average monthly production we have contributed are quite significant, and hence they have to be taken into account for each earned value forecast so that a project becomes reliable.The authors would like to thank Gicaman SA, Eres SA, and Urvial SA (construction companies) by the cession of their outcome data corresponding to 161 public promotions that gave rise to 5,319 subsidised housing.Ruiz-Fernández, JP.; Benlloch Marco, J.; López, MA.; Valverde-Gascueña, N. (2019). Influence of seasonal factors in the earned value of construction. Applied Mathematics and Nonlinear Sciences. 4(1):21-34. https://doi.org/10.2478/AMNS.2019.1.00003S213441Koehn, E., & Brown, G. (1985). Climatic Effects on Construction. Journal of Construction Engineering and Management, 111(2), 129-137. doi:10.1061/(asce)0733-9364(1985)111:2(129)El-Rayes, K., & Moselhi, O. (2001). Impact of Rainfall on the Productivity of Highway Construction. Journal of Construction Engineering and Management, 127(2), 125-131. doi:10.1061/(asce)0733-9364(2001)127:2(125)Kenley, R., & Wilson, O. D. (1989). A construction project net cash flow model. Construction Management and Economics, 7(1), 3-18. doi:10.1080/01446198900000002Skitmore, M. (1992). Parameter prediction for cash flow forecasting models. Construction Management and Economics, 10(5), 397-413. doi:10.1080/01446199200000038Chan, D. W. M., & Kumaraswamy, M. M. (1995). A study of the factors affecting construction durations in Hong Kong. Construction Management and Economics, 13(4), 319-333. doi:10.1080/01446199500000037Kaka, A. P., & Price, A. D. F. (1993). Modelling standard cost commitment curves for contractors’ cash flow forecasting. Construction Management and Economics, 11(4), 271-283. doi:10.1080/01446199300000027Blyth, K., & Kaka, A. (2006). A novel multiple linear regression model for forecasting S‐curves. Engineering, Construction and Architectural Management, 13(1), 82-95. doi:10.1108/09699980610646511Khosrowshahi, F., & Kaka, A. P. (2007). A Decision Support Model for Construction Cash Flow Management. Computer-Aided Civil and Infrastructure Engineering, 22(7), 527-539. doi:10.1111/j.1467-8667.2007.00508.

Determination of mass attenuation coefficient by numerical absorption calibration with Monte-Carlo simulations at 59.54 keV

International audienceThis study presents a numerical method in order to determine the mass attenuation coefficient of a sample with an unknown chemical composition at low energy. It is compared with two experimental methods : a graphic method and a transmission method. The method proposes to realise a numerical absorption calibration curve to process experimental results. Demineralised water with known mass attenuation coefficient (0.2066 cm 2 .g −1 at 59.54 keV) is chosen to confirm the method. 0.1964 ± 0.0350 cm 2 .g −1 is the average value determined by the numerical method, that is to say less than 5% relative deviation compared to more than 47% for the experimental methods

Multiple Mobile Agent System Framework Suitable for Pervasive Computing

In this article we present a formal framework based on the action and reaction model that allows us to cover the dynamics of multi-agent systems (MAS) made up of mobile software agents suitable for scalable networks. This model is based on the operation of the human nervous centres. At the present time, we are applying it in works related with the control of biological systems and also in those related to the network management. In the case of systems based on mobile agents, the main problem is the different vision the agents have of the world and the impossibility of being aware of and synchronizing all the influences brought by the different agents acting on it. We have compared our proposal with the conventional MAS by solving an extension of the predator-prey problem. The results show the advantages of mobility as the size of the problem grows in a distributed system