Buckling instability of web plastifying dampers: analytical and numerical approach

This paper describes a numerical study on the instability of a brace-type seismic damper based on the out of plane yielding of the web of wide-flange steel sections (Web Plastifying Damper, WPD)The damper is intended to be installed in a framed structure as a standard diagonal brace. Under lateral forces, the damper is subjected to high axial forces, therefore its buckling instability is a matter of concern. Several finite element models representing WPDs with different axial stiffness and various geometries of their components were developed and analyzed taking into account both material and geometrical nonlinearities. The influence of several parameters defining the WPD in the load-displacement curve was examined. Furthermore, a simplified model to predict the buckling load is proposed.

PAH occurrence during combustion of biodiesel from various feedstocks

PAHs are pollutants of concern since they are known carcinogenic compounds. Their occurrence is mainly related to combustion or pyrolysis of organic matter such as fossil fuels. In the current scenario where biofuels are growingly important, it is also necessary to characterize PAH emissions due to their combustion. There are a number of works concerning PAH emissions from biodiesel combustion in Diesel engines, however, there are few regarding the difference between them depending on the feedstock and type of alcohol used in the transesterification. The authors have processed and characterized biodiesel from several feedstocks (Le. tallow, palm, rapeseed, soy-bean, coconut, peanut and linseed oils) to obtain FAME and FAEE and they have developed a method to measure the PAHs originated during their combustion in a bomb calorimeter. The tests have been carried out under different oxygen pressure conditions, and samples have been c1eaned from the bomb after each one of these tests. The samples have been prepared for GC-MS analysis, where PAH quantities among some other combustion products have been assessed. This work shows statistical relations obtained between the measured amounts of 18 PAHs of concern and the composition (oil and type of alcohol) used to obtain the biodiesel, and also the oxygen pressure during combustion.

Spatial and temporal variations of trace element distribution in soils and street dust of an industrial town in NW Spain: 15 years of study

Extensive spatial and temporal surveys, over 15 years, have been conducted in soil in urban parks and street dusts in one of the most polluted cities in western Europe, Avilés (NW Spain). The first survey was carried out in 1996, and since then monitoring has been undertaken every five years. Whilst the sampling site is a relatively small town, industrial activities (mainly the steel industry and Zn and Al metallurgy) and other less significant urban sources, such as traffic, strongly affect the load of heavy metals in the urban aerosol. Elemental tracers have been used to characterise the influence of these sources on the composition of soil and dust. Although PM10 has decreased over these years as a result of environmental measures undertaken in the city, some of the “industrial” elements still remain in concentrations of concern for example, up to 4.6% and 0.5% of Zn in dust and soil, respectively. Spatial trends in metals such as Zn and Cd clearly reflect sources from the processing industries. The concentrations of these elements across Europe have reduced over time, however the most recent results from Avilés revealed an upward trend in concentration for Zn, Cd, Hg and As. A risk assessment of the soil highlighted As as an element of concern since its cancer risk in adults was more than double the value above which regulatory agencies deem it to be unacceptable. If children were considered to be the receptors, then the risk nearly doubles from this element.

An interactive web-based learning assistant for structural analysis of continuous beams

There are significant levels of concern about the relevance and the difficulty of learning some issues on Strength of Materials and Structural Analysis. Most students of Continuum Mechanics and Structural Analysis in Civil Engineering usually point out some key learning aspects as especially difficult for acquiring specific skills. These key concepts entail comprehension difficulties but ease access and applicability to structural analysis in more advanced subjects. Likewise, some elusive but basic structural concepts, such as flexibility, stiffness or influence lines, are paramount for developing further skills required for advanced structural design: tall buildings, arch-type structures as well as bridges. As new curricular itineraries are currently being implemented, it appears appropriate to devise a repository of interactive web-based applications for training in those basic concepts. That will hopefully train the student to understand the complexity of such concepts, to develop intuitive knowledge on actual structural response and to improve their preparation for exams. In this work, a web-based learning assistant system for influence lines on continuous beams is presented. It consists of a collection of interactive user-friendly applications accessible via Web. It is performed in both Spanish and English languages. Rather than a “black box” system, the procedure involves open interaction with the student, who can simulate and virtually envisage the structural response. Thus, the student is enabled to set the geometric, topologic and mechanic layout of a continuous beam and to change or shift the loading and the support conditions. Simultaneously, the changes in the beam response prompt on the screen, so that the effects of the several issues involved in structural analysis become apparent. The system is performed through a set of web pages which encompasses interactive exercises and problems, written in JavaScript under JQuery and DyGraphs frameworks, given that their efficiency and graphic capabilities are renowned. Students can freely boost their self-study on this subject in order to face their exams more confidently. Besides, this collection is expected to be added to the "Virtual Lab of Continuum Mechanics" of the UPM, launched in 2013 (http://serviciosgate.upm.es/laboratoriosvirtuales/laboratorios/medios-continuos-en-construcci%C3%B3n)

A CO2-saving-based methodology to measure the impact of the SUMP in European Cities: Application to the City of Burgos

Urban mobility in Europe is always a responsibility of the municipalities which propose measures to reduce CO2 emissions in terms of mobility aimed at reducing individual private transport (car). The European Commission's Action Plan on Urban Mobility calls for an increase in the take-up of Sustainable Urban Mobility Plans in Europe. SUMPs aim to create a sustainable urban transport system. Europe has got some long term initiatives and has been using some evaluation procedures, many of them through European projects. Nevertheless, the weak point with the SUMPs in Spain, has been the lack of concern about the evaluation and the effectiveness of the measures implemented in a SUMP. For this reason, it is difficult to know exactly whether or not the SUMPs have positively influenced in the modal split of the cities, and its contribution to reduce CO2 levels. The case of the City of Burgos is a very illustrative example as it developed a CiViTAS project during the years 2005-2009, with a total investment of 6M?. The results have been considered as ?very successful? even at European level. The modal split has changed considerably for better, The cost-effectiveness ratio of the SUMP in the city can be measured with the CO2 ton saved, specifically 36 ? per CO2 ton saved, which is fully satisfactory and in line with calculations from other European researchers. Additionally, the authors propose a single formula to measure the effectiveness of the activities developed under the umbrella of a SUMP.

New systems of management to improve the health and welfare of rabbits in farm conditions = Nuevos sistemas de cría y manejo para mejorar la salud y bienestar de conejos de granja

El objetivo general de esta Tesis Doctoral fue evaluar nuevos sistemas de alojamiento y cría de conejos de granja, estudiando tanto parámetros comportamentales (experimento 1) como productivos y reproductivos (experimento 3). Además, se evaluaron diferentes técnicas de muestreo con el fin de optimizar el tiempo empleado para el estudio del comportamiento animal (experimento 2). En el experimento 1, se estudió el comportamiento de conejas alojadas en dos tipos de jaulas (TJ), convencionales vs. alternativas con una plataforma elevada, en distintos estados fisiológicos (EF), lactantes y gestantes. Se observó el comportamiento de 12 conejas reproductoras con grabaciones de una duración de 24 h continuas. Independientemente del EF y TJ, las conejas pasaron gran parte de su tiempo sobre el reposapatas (57,7 %, de media). Sin embargo, debido al uso de la plataforma (23,0% del tiempo, de media), las conejas lactantes permanecieron un 36,6 % menos de tiempo (P<0,001) sobre el reposapatas y las gestantes un 27,0% menos (P<0,001) sobre el enrejillado en jaulas alternativas que en convencionales. En las jaulas alternativas, las conejas podían adoptar la postura “levantada”, sin embargo ésta fue observada solamente en conejas gestantes una media de 4,6 veces al día. Las conejas bebieron con mas frecuencia en jaulas convencionales que en alternativas (24,6 vs 19,1 veces al día; P<0,05). Se observó una mayor duración y frecuencia del comportamiento “interactuando con compañeras” en conejas gestantes alojadas en jaulas convencionales (276 s/d y 4,6 veces/d; P<0,05). La frecuencia de “interactuando con gazapos” fue menor en jaulas alternativas que en convencionales (2,4 vs 8,6 veces al día; P<0,01). La hora del día afectó al comportamiento de las conejas, teniendo un comportamiento menos activo durante las horas centrales del día. Durante las horas de oscuridad, las conejas estuvieron más inquietas realizando comportamientos como ‘encabritarse’ o amamantar, coincidiendo éstos en el tiempo en el cual las conejas pasaron más tiempo en la plataforma. Las conejas utilizaron frecuentemente la plataforma, independientemente del estado fisiológico. En la fase de lactación, las conejas utilizaron la plataforma para huir de los intentos de mamar por parte de los gazapos cuando éstas no estaban receptivas. El uso de la plataforma puede dar lugar a problemas higiénicos debidos tanto por la acumulación de heces sobre ella como por la caída de heces y orina sobre los animales que están en la parte inferior. La ausencia de estereotipias por parte de las conejas tanto en jaulas alternativas como en convencionales no sugiere una falta de bienestar debida al sistema de alojamiento. En el experimento 2, se compararon distintos métodos de observación simplificada con respecto un método de referencia usando grabaciones continuas de 24 h para la evaluación del comportamiento de conejas en distintos estados fisiológicos (gestantes y lactantes) alojadas en dos tipos de jaulas (convencionales y alternativas). Se analizaron un total de 576 h de grabaciones continuas de 24 h en 12 conejas reproductoras al final del periodo de lactación y en las mismas conejas después del destete. Los comportamientos observados se clasificaron en tres categorías independientes (localización en la jaula, postura y comportamientos funcionales). Se utilizaron grabaciones continuas de 24 h como método de referencia para validar otros cuatro métodos de observación simplificados, utilizando grabaciones de distinta duración y frecuencia a lo largo del día. Métodos regulares: corto y largo con 2.4 y 8 h de observación respectivamente, y métodos irregulares: corto y largo con 6 y 8 h de observación, respectivamente. Como resultado, se observó que independientemente del sistema de alojamiento, el mejor método para reducir el tiempo de observación necesario para evaluar el comportamiento de conejas reproductoras depende del tipo de variable a estudiar y del estado fisiológico de las conejas. En gestantes, los métodos irregulares no fueron adecuados para estimar comportamientos de larga duración tales como tumbada, sentada, descansando y acicalándose. Sin embargo, en ambos estados fisiológicos, los métodos regulares fueron precisos para los comportamientos de los grupos localización y postura y para comportamientos funcionales de larga duración. Por otro lado, los coeficientes de variación de los comportamientos poco frecuentes realizados principalmente durante el periodo de oscuridad fueron muy altos, y el método irregular largo obtuvo los menores errores de estimación para éstos comportamientos. En el experimento 3, se estudió el efecto de un uso combinado de lactaciones largas (hasta 46 días) con jaulas alternativas sobre los parámetros productivos y reproductivos de 104 conejas y sus camadas durante cinco ciclos reproductivos. La mitad de las conejas fueron alojadas en jaulas polivalentes convencionales (39 cm x 100 cm x 30 cm) y la otra mitad en jaulas polivalentes alternativas (39 cm x 100 cm x 60 cm), con una plataforma elevada. Dentro de cada grupo de alojamiento, la mitad de las conejas se destetaron a 32 días y la otra mitad a 46 días tras el parto. Las lactaciones más largas afectaron negativamente al peso (P<0,001), contenido en grasa y energía (P<0,05) de las conejas al final del periodo de lactación, pero éste efecto disminuyó con el número de partos. La fertilidad, prolificidad y la mortalidad de las conejas no fue afectada por la duración de la lactación. El destete tardío dio lugar a un mayor tamaño y peso de la camada al final del periodo de crecimiento (8,9 y 11,3 %, respectivamente) y a un menor índice de conversión por jaula durante el todo el periodo experimental (13,5 %) con respecto al destete convencional (P<0,001). Éstos resultados fueron paralelos a la menor mortalidad global (12,6 vs 17,6 %; P<0,05) observada en gazapos con destete tardío. Las diferencias en los parámetros productivos con las distintas edades al destete sólo fueron observadas en los ciclos con peor estado sanitario (tercer y quinto ciclo), en los cuales el destete tardío redujo la mortalidad. El tipo de jaula no afectó al peso de la coneja, condición corporal, mortalidad, fertilidad ni tamaño de camada durante los cinco primeros ciclos reproductivos. Sin embargo, el peso de la camada y el índice de conversión a los 21 días de edad fueron 4,2% mayor (P<0,001) y 5,0% menor (P<0,005) en animales alojados en jaulas alternativas que en jaulas convencionales. A día 59 las jaulas alternativas dieron lugar a camadas más pesadas (P<0,01); sin embargo, éste efecto fue influenciado por la densidad alcanzada en cada ciclo, ya que cuando la densidad de los animales fue menor que 40kg/m2 (tercer y quinto ciclo), el efecto del tipo de jaula sobre el peso de la camada no fue significativo. De los resultados obtenidos se puede concluir que el uso combinado de lactaciones más largas y jaulas con mayor superficie disponible con una plataforma elevada podría ser una alternativa para mejorar el bienestar animal en determinadas situaciones productivas. ABSTRACT The general aim of this PhD Thesis was to evaluate new housing and husbandry systems of farmed rabbits, studying behavioral (experiment 1), productive and reproductive (experiment 3) parameters. Moreover, different sampling techniques were evaluated in order to optimize the assessment of rabbit behaviour (experiment 2). In experiment 1, the behaviour of rabbit does housed in two different types of cage (TC), conventional vs. alternative with an elevated platform, at different physiological stages (PS), lactation and gestation was to study. Behavioural observations were carried out on 12 commercial rabbit does using continuous 24 hour video recording. Independently of PS and TC, rabbit does spent most of their time on foot mats (57.7 %, as average). However, due to the use of platforms (23.0% of time, as average), lactating does spent 36.6% less time (P<0.001) on foot mats and gestating does spent 27.0% less (P<0.001) time on wire mesh in alternative cages than in conventional cages. Alternative cages allowed for standing posture but this behaviour was only observed in gestating does (4.6 times a day, as average). Frequency of drinking was higher in conventional than in alternative cages (24.6 vs. 19.1 times a day; P<0.05). Gestating does housed in conventional cages reached the highest duration and frequency of interacting with neighbours (276 s/d and 4.6 times/d; P<0.05). The frequency of interacting with kits was lower in alternative than in conventional cages (2.4 vs. 8.6 times a day; P<0.01). Does’ behaviour was influenced by hour of day, being less active at the midday hours. During dark hours rabbit does more frequently performed restless behaviour such as hyperactivity or nursing, matching the time at which rabbit does spent more time on the platform. The platform was frequently used by rabbit does, independent of their physiological state, and during late lactation phase, when mothers were not receptive to nursing, does housed in alternative cages used the platform as a mean to flee from kids trying to suckle. The use of the platform might lead to hygienic problems due to retained faeces on the platform and faeces and urine falling onto animals located in the lower part of the cage. Stereotypies were not observed in any housing system, therefore conventional cages do not suggest lack of animal welfare. In experiment 2, it was compared the results of different simplified sampling methods of behavioural data with respect to reference records of 24-h in order to assess rabbit does behaviours at different physiological stages (gestation and lactation) in animals housed in two types of cages (conventional and alternative). A total of 576 h of continuous video of 12 rabbit does at the end of lactation and on the same females after weaning were analysed. The behavioural observations were studied using three independent categories of classification (location in the cage, posture and functional behaviours). Continuous behavioural recordings of 24 h were considered as the reference method to validate another 4 sampling methods of data collection by aggregated video recordings of different frequency and duration (regular short and long methods with 2.4 and 8 h of observation respectively, and irregular short and long methods with 6 and 8 h of observation, respectively). The current results showed that, independently of housing system, the best method to reduce the total observation time required to assess rabbit does behaviour depends on the trait studied and physiological stage of does. In gestating does, irregular methods were not suitable to estimate behaviours of long duration such as lying, sitting, resting and grooming. However, in both physiological stages, regular methods were accurate for location behaviours, postures and functional behaviours of long duration. Instead, for the study of infrequent behaviours performed mainly during dark period, where coefficients of variation were high, the irregular long method led to the lowest mean estimation errors. In experiment 3, the effects of the combined use of long lactation periods (46 days) with alternative cages on the reproductive and growth performance of 104 rabbit does and their litters during five consecutive reproductive cycles were studied. Half of does were housed in conventional polyvalent cages (39 cm x 100 cm x 30 cm) and the other half in alternative polyvalent cages (39 cm x 100 cm x 60 cm), with a raised platform. Half of the rabbit does in each type of cages were weaned at 32 and the other half at 46 days after parturition. Longer lactations affected negatively to body weight (P<0.001), fat and energy content (P<0.05) of rabbit does at the end of the lactation period, but this effect decreased with the number of parturitions. Fertility, prolificacy and doe mortality were not affected by lactation length. Late weaning led to higher litter size (by 8.9 %) and litter weight (by 11.3 %) at the end of growing period and lower feed conversion ratio per cage during the overall experimental period (13.5 %) than standard weaning (P<0.001). These results were parallels to a lower mortality (12.6 vs 17.6 %; P<0.05) of young rabbit weaned later during the overall experimental period. Differences in performances at different weaning ages were only observed during cycles with worst health status (third and fifth cycles) in which late weaning decreased mortality. Type of cage did not affect doe body weight and body condition, mortality, fertility, prolificacy and litter size during the five firsts reproductive cycles. Nevertheless, at day 21 litter weight and feed conversion ratio were 4.2 % higher (P<0.001) and 5.0 % lower (P<0.005) in animals housed in alternative than in conventional cages. Alternative cages also led to heavier litters at 59 days (P<0.01); however, this effect was influenced by density reached in each cycle, as when the density of animals was lower than 40 kg/m2 (cycles three and five), the difference of litter weight between alternative and conventional cages was not significant. From the results obtained it can be concluded that the combined use of longer lactations and cages with higher available surface with a raised platform could be an alternative to improve animal welfare in some productive situations.

Spatio-temporal distribution of pyrethroids in soil in Mediterranean paddy fields

Purpose The demand of rice by the increase in population in many countries has intensified the application of pesticides and the use of poor quality water to irrigate fields. The terrestrial environment is one compartment affected by these situations, where soil is working as a reservoir, retaining organic pollutants. Therefore, it is necessary to develop methods to determine insecticides in soil and monitor susceptible areas to be contaminated, applying adequate techniques to remediate them. Materials and methods This study investigates the occurrence of ten pyrethroid insecticides (PYs) and its spatio-temporal variance in soil at two different depths collected in two periods (before plow and during rice production), in a paddy field area located in the Mediterranean coast. Pyrethroids were quantified using gas chromatography?mass spectrometry (GC?MS) after ultrasound-assisted extraction with ethyl acetate. The results obtained were assessed statistically using non-parametric methods, and significant statistical differences (p < 0.05) in pyrethroids content with soil depth and proximity to wastewater treatment plants were evaluated. Moreover, a geographic information system (GIS) was used to monitor the occurrence of PYs in paddy fields and detect risk areas. Results and discussion Pyrethroids were detected at concentrations ?57.0 ng g?1 before plow and ?62.3 ng g?1 during rice production, being resmethrin and cyfluthrin the compounds found at higher concentrations in soil. Pyrethroids were detected mainly at the top soil, and a GIS program was used to depict the obtained results, showing that effluents from wastewater treatment plants (WWTPs) were the main sources of soil contamination. No toxic effects were expected to soil organisms, but it is of concern that PYs may affect aquatic organisms, which represents the worst case scenario. Conclusions A methodology to determine pyrethroids in soil was developed to monitor a paddy field area. The use of water fromWWTPs to irrigate rice fields is one of the main pollution sources of pyrethroids. It is a matter of concern that PYs may present toxic effects on aquatic organisms, as they can be desorbed from soil. Phytoremediation may play an important role in this area, reducing the possible risk associated to PYs levels in soil.