3,632 research outputs found
Pollutant emissions in common-rail diesel engines in extraurban cycle: rapeseed oils vs diesel fuel
The new energy strategy of EU (i.e., Directive 2009/28/EC) requires increasing the use of biofuels in transports up to
at least 10% of the total fuel consumption. In the last years, the share of Diesel engines in automotive applications
reached about 55% in EU market, thus trying to widen the alternatives to Diesel fuel is very important. In this
framework straight vegetable oils (SVO) can represent one of the available possibilities at least in some specific
applications (i.e., public transportation, hybrid or marine propulsion, etc.). SVO properties may be very different
form Diesel fuel, thus operating a Diesel engine with SVO might result in some problems, especially in automotive
configuration where the electronic unit acts as if it is working with Diesel fuel. This reflects in possible engine power
and torque reduction, maintenance problems, and pollutant emissions during vehicles running. The latter aspect is the
focus of the present paper. In this work, we used a turbocharged, four stroke, four cylinders, water cooled, commonrail
multijet Diesel engine in automotive configuration to simulate the extraurban cycle according to the EU standard,
comparing pollutant emissions in case of SVO and gasoil fuelling
Inibição do crescimento micelial e da germinação de esporos de Thielaviopsis paradoxa por Bacillus subtilis e Bacillus pumilus.
O objetivo do trabalho foi avaliar os efeitos de Bacillus pumilus (QST 2808) e Bacillus subtilis (QST 713) na inibição da germinação de esporos e no crescimento micelial de Thielaviopsis paradoxa, agente causal da podridão abacaxi da cana-de-açúcar. O primeiro teste avaliou a taxa de crescimento micelial do patógeno em placas de Petri, totalizando 15 placas em três tratamentos (inoculação simultânea; 24 horas e 48 horas após o bioagente). Em seguida avaliou o crescimento micelial na presença dos metabólitos produzidos pelos agentes de biocontrole, adicionados ao meio batata-dextrose-ágar, em cinco concentrações (10%; 1%; 0,1%; 0,01%; 0,001%). No teste de germinação avaliou-se o porcentual de germinação dos conÃdios na presença dos agentes de biocontrole nas concentrações citadas anteriormente. Ambos os agentes de biocontrole apresentaram efeitos antagônicos significativos contra o patógeno, com destaque para B. subtilis
Adaptive learning of compressible strings
Suppose an oracle knows a string S that is unknown to us and that we want to determine. The oracle can answer queries of the form "Is s a substring of S?". In 1995, Skiena and Sundaram showed that, in the worst case, any algorithm needs to ask the oracle Sigma n/4 - O(n) queries in order to be able to reconstruct the hidden string, where Sigma is the size of the alphabet of S and n its length, and gave an algorithm that spends (Sigma - 1)n + O(Sigma root n) queries to reconstruct S. The main contribution of our paper is to improve the above upper-bound in the context where the string is compressible. We first present a universal algorithm that, given a (computable) compressor that compresses the string to Tau bits, performs q = O(Tau) substring queries; this algorithm, however, runs in exponential time. For this reason, the second part of the paper focuses on more time-efficient algorithms whose number of queries is bounded by specific compressibility measures. We first show that any string of length n over an integer alphabet of size Sigma with rle runs can be reconstructed with q = O(rle(Sigma + log nrle)) substring queries in linear time and space. We then present an algorithm that spends q is an element of O (Sigma g log n) substring queries and runs in O (n(logn + log Sigma) + q) time using linear space, where g is the size of a smallest straight-line program generating the string. (c) 2021 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/)
Thermomagnetic history effects in SmMnGe
The intermetallic compound SmMnGe, displaying multiple magnetic phase
transitions, is being investigated in detail for its magnetization behavior
near the 145 K first order ferromagnetic to antiferromagnetic transition
occuring on cooling, in particular for thermomagnetic history effects in the
magnetization data. The most unusual finding is that the thermomagnetic
irreversibility, [= M(T)-M(T)] at 135 K is higher in
intermediate magnetic field strengths. By studying the response of the sample
(i.e., thermomagnetic irreversibility and thermal hysteresis) to different
histories of application of magnetic field and temperature, we demonstrate how
the supercooling and superheating of the metastable magnetic phases across the
first order transition at 145 K contribute to overall thermomagnetic
irreversibility.Comment: 15 pages, 5 figures, to appear in Physical Review
Fungal contamination and aflatoxin content of maize, moringa and peanut foods from rural subsistence farms in South Haiti
Mycotoxins are toxic, low molecular weight compounds produced by fungi. Among them, aflatoxins are the most carcinogenic and they mainly impact on rural communities of developing countries. The present study supplies data on mycobiota and aflatoxin contamination in the most common food products consumed in Haiti. The study concerns analyses performed on 49 samples of meals and seeds collected in South Haiti and tested for fungal occurrence and aflatoxin content by HPLC-DAD technique. The results revealed that three main fungal genera affected Haitian food products: Aspergillus spp. (Section Flavi and Nigri), followed by Penicillium spp. and Fusarium spp. Aflatoxin was present in more than half of the samples of maize (Zea mays L.) kernels (55%), maize meal (57%) and moringa (Moringa oleifera Lam.) seeds (64%), and in 25% of peanut (Arachis hypogaea L.) samples. The tested food products were mostly contaminated by aflatoxin B1 (AFB1) followed by aflatoxin B2 (AFB2), while no aflatoxins type G were detected. The total concentration of aflatoxins in the positive samples was 228 mg/kg on average, i.e., fifty-seven and eleven times higher than the maximum levels allowed in Europe and USA, respectively. Both the presence of aflatoxigenic fungi and aflatoxin contamination in maize kernels seemed to be related to agricultural practices, such as weed control, irrigation and growing cycle length. These findings suggest that the Haitian population is strongly exposed to aflatoxin risk. This risk could be reduced by exploiting simple and accessible farming strategies for minimizing mycotoxin contamination, at least for maize
Understanding the social in a digital age
Datafication, algorithms, social media and their various assemblages enable massive connective processes, enriching personal interaction and amplifying the scope and scale of public networks. At the same time, surveillance capitalists and the social quantification sector are committed to monetizing every aspect of human communication, all of which threaten ideal social qualities, such as togetherness and connection. This Special Issue brings together a range of voices and provocations around ‘the social’, all of which aim to critically interrogate mediated human connection and their contingent socialities. Conventional methods may no longer be adequate, and we must rethink not only the fabric of the social but the very tools we use to make sense of our changing social formations. This Special Issue raises shared concerns with what the social means today, unpicking and rethinking the seams between digitization and social life that characterize today’s digital age
Aeroelastic-structural coupling in antenna prototype for windy open-space
The interaction between wind and an antenna prototype for the low-frequency radio telescope of the Square Kilometer Array (SKA) is experimentally tested in the wind tunnel of the Politecnico di Torino. The tests aim to predict the antenna behaviour during working conditions, i.e. mounted by means of five contact points to a metal grid on sandy ground in the Australian desert. The wind tunnel is characterised by a circular test section having a diameter equal to 3 m and a length equal to 5 m. The height and the distance between the lateral legs of the antenna are equal respectively to 2.2 m and 1.5 m. The tests were performed at increasing wind speed up to 110 km/h. The system under analysis is an aluminium antenna composed by four parts arranged in axial symmetry and each one made of fifteen rods and small plates/wire elements. A numerical parametric model of the system is developed to numerically study the dynamic behaviour of the antenna in the frequency range of interest. The model is able to handle very high modal density and closed spaced modes in multiplicity of four because of the symmetric structure as well as the different shapes of the elements forming the antenna. The wind tunnel results emphasise the fluid-structure coupling of aerodynamics modes and the critical aspects of the boundary conditions for a good prediction of the oscillations amplitudes
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