397 research outputs found

    Estimation of capital and operation costs of backhoe loaders

    No full text
    Accurate estimation of equipment costs is a key factor in feasibility study and evaluation of design alternatives of mining projects. In this paper, capital and operation costs of backhoe loaders are estimated using multiple linear regression (MLR), based on principle component analysis (PCA). These cost functions are consisted of five independent variables; bucket size, digging depth, dump height, weight and horse power. The MLR is conducted in two steps. At the first correlation between independent variables is omitted using PCA technique. Thereafter, MLR functions are established using selected significant PCs and total cost functions are constituted as functions of initial variables. At the end, accuracy of functions are evaluated using mean absolute error rate method

    Altered pituitary hormone secretion in male rats exposed to Bisphenol A

    Get PDF
    Bisphenol A (BPA) is a xenobiotic estrogenic compound. This compound has been suspected to have estrogenic effects on reproductive system of males and females. In this present study we investigated possible low-dose effects of BPAon Luteinizing Hormone in rats. Male Wistar rats (12-13 weeks old) were administrated a daily intra peritoneal 10 μg/kgbw/day, 50 μg/kgbw/day, 100 μg/kgbw/ day dose of BPA for 6, 6, and 12 days, and one day after last injection, serum level of Luteinizing Hormone was examined by ELISA method. All data were expressed as means ± SE. Two-way ANOVA was performed. Analysis of data showed that in all dose groups, plasma level of Luteinizing Hormone significantly decreased compared to control group. The present study showed that BPA at low doses affects Luteinizing Hormone, one of main hormones in spermatogenesis in the adult Wistar rats, and subsequently alters the steroidgenesis in testicular Leydig cells

    A comparative study on the application of various artificial neural networks to simultaneous prediction of rock fragmentation and backbreak

    Get PDF
    AbstractIn blasting operation, the aim is to achieve proper fragmentation and to avoid undesirable events such as backbreak. Therefore, predicting rock fragmentation and backbreak is very important to arrive at a technically and economically successful outcome. Since many parameters affect the blasting results in a complicated mechanism, employment of robust methods such as artificial neural network may be very useful. In this regard, this paper attends to simultaneous prediction of rock fragmentation and backbreak in the blasting operation of Tehran Cement Company limestone mines in Iran. Back propagation neural network (BPNN) and radial basis function neural network (RBFNN) are adopted for the simulation. Also, regression analysis is performed between independent and dependent variables. For the BPNN modeling, a network with architecture 6-10-2 is found to be optimum whereas for the RBFNN, architecture 6-36-2 with spread factor of 0.79 provides maximum prediction aptitude. Performance comparison of the developed models is fulfilled using value account for (VAF), root mean square error (RMSE), determination coefficient (R2) and maximum relative error (MRE). As such, it is observed that the BPNN model is the most preferable model providing maximum accuracy and minimum error. Also, sensitivity analysis shows that inputs burden and stemming are the most effective parameters on the outputs fragmentation and backbreak, respectively. On the other hand, for both of the outputs, specific charge is the least effective parameter

    La preferencia ecológico versus convencional en los productos lácteos: el caso del queso

    Get PDF
    Las nuevas exigencias de los consumidores hacia todo lo relacionado con la calidad y la seguridad de los productos agroalimentarios están provocando un cambio progresivo en los hábitos de compra y de consumo de dichos productos. Concretamente, en el sector lácteo los consumidores buscan cada vez más productos de mayor calidad, más sanos, naturales, ecológicos, artesanales, locales etc., y en definitiva, más saludables y respetuosos con el medioambiente. Las nuevas tendencias del consumo alimentario hacia estos nuevos productos están provocando una continua adaptación de las empresas productoras para satisfacer estas demandas y, por consiguiente, poder competir en el mercado. Dentro del sector lácteo, los productos lácteos artesanales (PLA) y sobre todo los derivados de la ganadería de pequeños rumiantes, forman parte del patrimonio de productos agroalimentarios de las regiones más desfavorecidas en muchos países de la región mediterránea. Dichos productos constituyen un recurso endógeno con un claro potencial de desarrollo, no siempre bien aprovechado y revalorizado, particularmente, en España. Varias razones tanto relacionadas con la demanda y los mercados, como con la potencialidad productiva primaria y, sobre todo, secundaria avalan dicho potencial. Analizando dicho sector, uno de los productos con un alto potencial de desarrollo es el queso artesanal. En este sentido, debido a la creciente importancia de la producción ecológica en la dieta alimentaria y la orientación progresiva de los consumidores hacia dichos productos, entre las oportunidades comerciales que se presentan para el queso, es la diferenciación hacia la calidad ecológica. No obstante, como dicha diferenciación no parece resultar suficiente para incrementar el consumo, parece de gran interés analizar la estructura de preferencias de los consumidores en relación con unos atributos del queso, y estimar la importancia relativa del atributo modo de producción (ecológica vs convencional) frente a otras características del mismo tal como el tipo de leche, el proceso de elaboración (industrial, de pequeñas industrias o artesanal) y el precio. Asimismo, se han intentado estimar los precios implícitos de las variaciones en los niveles de los diferentes atributos, básicamente, la disposición a pagar de los consumidores por la calidad ecológica frente al convencional. La información manejada en este trabajo proviene de una encuesta realizada a 263 consumidores de queso en Andalucía. El cuestionario tiene dos grandes bloques. En el primero se incluye un test de preferencias de los entrevistados hacia unos perfiles de quesos. En el segundo se recogen las características sociodemográficas y de estilo de vida de los encuestados.Instituto de Investigación y Formación Agraria IFAPA Centro Camino de Purchil, Granada. Área de Economía y Sociología Agrarias

    Polyphenols content, antioxidant and antimicrobial activities of extracts of some wild plants collected from the south of Tunisia

    Get PDF
    25 wild plants were collected from the south of Tunisia. The dried aerial parts were extracted under a continuous reflux set-up in a Soxhlet extractor with hexane, ethyl acetate, methanol and water. The extracts were screened for total phenolic content, antioxidant and antimicrobial activities. Total phenolic contents were determined using a spectrophotometric technique, based on the Folin-Ciocalteau reagent and calculated as pyrogallol equivalents (PyE) per 100 g of dry weight (dw). Total phenolic content ranged from traces to 2225 ± 267 mg PyE/100 g dw in Periploca angustifolia hexane extract and Erodium glaucophyllum methanol extract, respectively. Total flavonoids and flavonols weremeasured by a colorimetric assay and expressed as mg of rutin equivalents (RuE) per 100 g dw and mg of quercetin equivalents (QuE) per 100 g dw respectively. The highest amounts of flavonoids of 315 mgRuE/100 g dw and of flavonols of 63 mg QuE/100 g dw was recorded in the ethyl acetate extract of Acacia radiana. The antioxidant capacity of all extracts was evaluated with the (1,1-diphenyl-2-picrylhydrazyl, DPPH and 2,2'-azino-bis [3-ethylbenzthiazoline-6-sulphonic acid]) ABTS tests. Several extracts showed antioxidant capacity higher than (butylated hydroxytoluene) BHT. Different trend was observed for each antioxidant system with respect to solvents used. All tested plants showedantimicrobial activity, but this activity depended closely on the nature of the solvent used and of the microorganism tested. Rhanterium suaveolens ethyl acetate extract showed the largest spectre of antibacterial activity and Bassia indica ethyl acetate extract showed the highest antifungal activity.Interestingly, some of the collected plants had a high phenolic content and powerful antioxidant and antimicrobial activities. These plants may serve as sources of antioxidants with new chemotypes and potential beneficial health properties

    Massive Increase, Spread, and Exchange of Extended Spectrum {beta}-Lactamase-Encoding Genes Among Intestinal Enterobacteriaceae in Hospitalized Children With Severe Acute Malnutrition in Niger.

    Get PDF
    Background. From the time of CTX-M emergence, extended-spectrum β-lactamase-producing enterobacteria (ESBL-E) have spread worldwide in community settings as well as in hospitals, particularly in developing countries. Although their dissemination appears linked to Escherichia coli intestinal carriage, precise paths of this dynamic are largely unknown. Methods. Children from a pediatric renutrition center were prospectively enrolled in a fecal carriage study. Antibiotic exposure was recorded. ESBL-E strains were isolated using selective media from fecal samples obtained at admission and, when negative, also at discharge. ESBL-encoding genes were identified, their environments and plasmids were characterized, and clonality was assessed with polymerase chain reaction-based methods and pulsed-field gel electrophoresis for E. coli and Klebsiella pneumoniae. E. coli strains were subjected to multilocus sequence typing. Results. The ESBL-E carriage rate was 31% at admission in the 55 children enrolled. All children enrolled received antibiotics during hospitalization. Among the ESBL-E-negative children, 16 were resampled at discharge, and the acquisition rate was 94%. The bla(CTX-M-15) gene was found in >90% of the carriers. Genetic environments and plasmid characterization evidenced the roles of a worldwide, previously described, multidrug-resistant region and of IncF plasmids in CTX-M-15 E. coli dissemination. Diversity of CTX-M-15-carrying genetic structures and clonality of acquired ESBL E. coli suggested horizontal genetic transfer and underlined the potential of some ST types for nosocomial cross-transmission. Conclusions. Cross-transmission and high selective pressure lead to very high acquisition of ESBL-E carriage, contributing to dissemination in the community. Strict hygiene measures as well as careful balancing of benefit-risk ratio of current antibiotic policies need to be reevaluated

    Le secteur caprin laitier andalou : Stratégies de recherche, développement et formation afin d’augmenter la valeur ajoutée des fromages artisanaux

    Get PDF
    Résumé. Le secteur caprin laitier andalou produit 50% du lait de l’Espagne et possède des opportunités de développement très claires utilisant des races autochtones et des grandes surfaces de pâturages disponibles. La production de fromages de chèvre en Andalousie peut être considérée comme un modèle de développement rural durable. Différents organismes publics et privés ont créé récemment un réseau de travail multidisciplinaire pour travailler sur la promotion et le développement des fromages artisanaux andalous, en établissant des stratégies de recherche, de développement et de formation destinées à la valorisation de ces fromages, spécialement ceux de chèvre. A partir des résultats d’une analyse stratégique, le présent travail propose des activités de recherche, de développement et de formation consacrées à la caractérisation de la qualité des fromages artisanaux, aux études de marché sur la connaissance et la perception de la qualité, aux activités de formation spécialisée dans la fromagerie et aux activités de promotion.Abstract. The Andalusian dairy goat sector (representing 50% of the national goat milk production) has potential opportunities for development using autochthonous breeds and semi-extensive production systems. Goat cheese production in Andalusia can be considered as a model for a sustainable rural development. Public institutions of research, development, and training as well as private ones have recently created a multidisciplinary and multinstitutional network to perform actions in favour of the marketing and promotion of the andalusian goat cheeses. In this paper, through the results of a strategic analysis, some research, development, and training actions were proposed. These actions are related with the improvement of quality, and the definition of the hand made cheese attributes; studies on the demand side, and consumer perception of quality; and those related to training and promotion

    Flexible connectivity and QoE/QoS management for 5G networks: the 5G NORMA view

    Get PDF
    Proceeding of: 2016 IEEE International Conference on Communications Workshops (ICC)The goal envisioned by 5G NORMA is to develop a novel, adaptive and future-proof 5G mobile network architecture. In order to fulfill these requirements, 5G NORMA envisions an extremely flexible architecture to be deployed in a multi-tier distributed data-center. In this paper we focus on the novel mobility management schemes, QoE/QoS, Control and Orchestration mechanisms that are being developed in 5G NORMA. These modules, that follow the software-defined principle, jointly optimize core and access functions. The final result is a modular architecture that adapts to the requirements of very heterogeneous services, while allowing multiple tenants to share network resources among them, providing hence the flexible connectivity needed by future 5G Networks.This work has been performed in the framework of the H2020-ICT-2014-2 project 5G NORMA

    Evaluation of native microalgae from Tunisia using the pulse-amplitude-modulation measurement of chlorophyll fluorescence and a performance study in semi-continuous mode for biofuel production

    Get PDF
    Background: Microalgae are attracting much attention as a promising feedstock for renewable energy production, while simultaneously providing environmental benefits. So far, comparison studies for microalgae selection for this purpose were mainly based on data obtained from batch cultures, where the lipid content and the growth rate were the main selection parameters. The present study evaluates the performance of native microalgae strains in semi-continuous mode, considering the suitability of the algal-derived fatty acid composition and the saponifiable lipid productivity as selection criteria for microalgal fuel production. Evaluation of the photosynthetic performance and the robustness of the selected strain under outdoor conditions was conducted to assess its capability to grow and tolerate harsh environmental growth conditions. Results: In this study, five native microalgae strains from Tunisia (one freshwater and four marine strains) were isolated and evaluated as potential raw material to produce biofuel. Firstly, molecular identification of the strains was performed. Then, experiments in semi-continuous mode at different dilution rates were carried out. The local microalgae strains were characterized in terms of biomass and lipid productivity, in addition to protein content, and fatty acid profile, content and productivity. The marine strain Chlorella sp. showed, at 0.20 1/day dilution rate, lipid and biomass productivities of 35.10 mg/L day and 0.2 g/L day, respectively. Moreover, data from chlorophyll fluorescence measurements demonstrated the robustness of this strain as it tolerated extreme outdoor conditions including high (38 ° C) and low (10 ° C) temperature, and high irradiance (1600 µmol/m2 s). Conclusions: Selection of native microalgae allows identifying potential strains suitable for use in the production of biofuels. The selected strain Chlorella sp. demonstrated adequate performance to be scaled up to outdoor conditions. Although experiments were performed at laboratory conditions, the methodology used in this paper allows a robust evaluation of microalgae strains for potential market applications.This study was supported by the Marine Microalgae Biotechnology Group at the University of Almer'a (BIO 173) and the Campus de Excelencia Internacional Agroalimentario (ceiA3) within the joint framework of supervised theses between the University of Almeria, Spain and the University of Sfax, Tunisia.Scopu

    Mobile network architecture evolution toward 5G

    Get PDF
    As a chain is as strong as its weakest element, so are the efficiency, flexibility, and robustness of a mobile network, which relies on a range of different functional elements and mechanisms. Indeed, the mobile network architecture needs particular attention when discussing the evolution of 3GPP EPS because it is the architecture that integrates the many different future technologies into one mobile network. This article discusses 3GPP EPS mobile network evolution as a whole, analyzing specific architecture properties that are critical in future 3GPP EPS releases. In particular, this article discusses the evolution toward a "network of functions," network slicing, and software-defined mobile network control, management, and orchestration. Furthermore, the roadmap for the future evolution of 3GPP EPS and its technology components is detailed and relevant standards defining organizations are listed.This work has been performed in the framework of the H2020-ICT-2014-2 project 5G NORMA
    corecore