Influence of the particle size distribution on the stifness of granitic materials

A presente comunicação apresenta a avaliação das características de deformabilidade obtidas com recurso a um equipamento triaxial de precisão, sobre três granulometrias diferentes da mesma origem geológica (formação granítica), a saber: uma areia siltosa (D50=0.36mm) designada de Areia de Perafita, e dois agregados graníticos, um (0/12.5) e outro (0/31.5). Os ensaios foram realizados sobre provetes reconstituídos por compactação sobre amostras no estado não saturado, tendo-se procedido à medição das pressões intersticiais negativas, de modo a se poderem também analisar os resultados em termos de tensões efectivas. Os resultados obtidos evidenciaram, para um determinado nível de tensão, um aumento do módulo de deformabilidade (normalizado para o mesmo índice de vazios) com a diminuição da dimensão máxima das partículas.In this paper is presented the stiffness of three materials with the same geological origin, a silty sand designed Perafita sand (D50=0.36mm) and two granite aggregates, one (0/12.5) and another (0/31.5). The stiffness of the compacted materials was studied by means of precision triaxial tests. The influence of non-saturation into the stiffness is also studied through triaxial tests with measurements of negative pore water pressures. Such measurements allow the analysis of the mechanical behaviour of the unsaturated materials in terms of effective stresses. The results obtained show, for a certain stress level, an increasing of the Young’s modulus (normalised for a certain void ratio) with the decreasing of the maximum size of particles.GRICES/CNRS – projecto “Security of road and railway infrastructures versus climatic changes

Interference-aware iterative block decision feedback equalizer for single-carrier transmission

The deployment of increasingly dense heterogeneous mobile networks can create high levels of interference among users that, combined with severely time-dispersive channels, can result in substantial performance degradation. To cope with both effects, in this paper, we propose an iterative block decision feedback equalizer (IBDFE) for single carrier (SC) transmissions that makes use of the correlation between the interference in the receiving antennas and minimizes the mean squared error (MSE) of the detected symbols. Our analytic and simulated performance results show that the proposed receiver can clearly outperform the conventional IBDFE and the linear interference rejection combining (IRC) detector in severely time-dispersive channels with strong cochannel interference.info:eu-repo/semantics/acceptedVersio

Sternoclavicular Joint Septic Arthritis in a Healthy Adult: a Rare Diagnosis with Frequent Complications

We report a case of complicated sternoclavicular joint septic arthritis in a previously healthy adult with no risk factors. An 83-year-old female presented to the emergency with a 1-week history of right shoulder pain followed by fever and prostration in the last 48 h. Computed tomography (CT) scan findings were consistent with right sternoclavicular joint (SCJ) septic arthritis complicated by periarticular abscess. Emergent surgical debridement was performed by a surgical team composed of orthopaedic and thoracic surgeons, followed by 6 weeks of antibiotic treatment. This case highlights the diagnosis and surgical treatment of a rare septic arthritis location but with frequent complications as well as the importance of multidisciplinary collaboration.info:eu-repo/semantics/publishedVersio

Influencia de la no saturación y granulometría en la rigidez de materiales de naturaleza granítica

In this paper, the stiffness of two materials with the same geological origin is presented, a silty sand, called Perafita sand (D50=0.36mm) and a granite aggregate (0/12.5, D50=0.52mm). The stiffness in very small strains ( <10-5) of the compacted materials is studied by means of precision triaxial tests (with local strain measurements). The influence of non-saturation on the stiffness is also studied through triaxial tests with measurement of negative pore water pressures. Such measurements allow the analysis of the mechanical behaviour of the unsaturated material in terms of effective stresses. For this purpose two approaches were used: the Terzaghi’s and Bishop’s approaches. The results obtained show, for each material, a unique relationship between vertical stiffness and vertical effective stress (constant void ratio = 0.5), independently of the saturation degree of the studied samples.En este artículo se presenta la rigidez de dos materiales con el mismo origen geológico, una arena con limo, llamada arena Perafita (D50=0.36mm) y un agregado granítico (0/12.5, D50=0.52mm). La rigidez para deformaciones muy pequeñas ( <10-5) de los materiales compactados es estudiada mediante ensayos triaxiales de precisión (con medidas locales de deformación). La influencia de la no-saturación en la rigidez se ha estudiado también mediante ensayos triaxiales con medición de la presión negativa del agua en los poros. Estas medidas permiten el análisis del comportamiento mecánico de materiales no saturados por lo que se refiere a tensiones efectivas. Con este propósito fueron usados dos procedimientos: el de Terzaghi y el de Bishop. Los resultados obtenidos revelan, para cada material, una relación única entre la rigidez vertical y la tensión efectiva vertical (ratio de vacíos constante = 0.5), independientemente del grado de saturación de las muestras estudiadas

Stifness and influence of non-saturation in granitic materials

Neste artigo, apresentam-se as características de deformabilidade para dois materiais com a mesma origem geológica: um agregado granítico (0/12.5; D50=0.52mm) e uma areia siltosa designada de areia de Perafita (0/6.35; D50=0.36mm). A rigidez, dos materiais compactados, no domínio das pequenas deformações (<10-5) é estudada através de ensaios triaxiais de precisão. A influência da não saturação na deformabilidade dos materiais é estudada através de ensaios triaxiais com medição das pressões intersticiais. Tais medidas permitiram a análise do comportamento mecânico dos materiais não saturados em termos de tensões efectivas, que foram calculadas através das aproximações de Terzaghi e Bishop. Os resultados obtidos mostram para cada material uma relação única entre o módulo de deformabilidade e a tensão efectiva (para e=0.5), independentemente do grau de saturação das amostras ensaiadas.In this paper, the stiffness of two materials with the same geological origin is presented, a granite aggregate (0/12.5, D50=0.52mm) and a silty sand, called Perafita sand (0/6.35; D50=0.36mm). The stiffness in very small strains (<10-5) of the compacted materials is studied by means of precision triaxial tests. The influence of non-saturation on the stiffness is also studied through triaxial tests with measurement of negative pore water pressures. Such measurements allow the analysis of the mechanical behaviour of the unsaturated material in terms of effective stresses. For this purpose two approaches were used: the Terzaghi’s and Bishop’s approaches. The results obtained show, for each material, a unique relationship between vertical stiffness and vertical effective stress (constant void ratio=0.5), independently of the saturation degree of the studied samples.Universidade de Coimbra. Faculdade de Ciências e Tecnologia (FCT-UC)GRICES/CNRS – “Security of road and railway infrastructures versus climatic changes

Strength of non-traditional granular materials assessed from drained multistage triaxial tests

When granular materials are applied in geotechnical works, like embankments and road pavement layers, one of the most relevant engineering properties in stability analysis is ultimate shear strength. In geotechnical engineering, the triaxial test is one of the most reliable methods available for determining ultimate shear strength. In this test, a soil specimen, compacted in laboratory or collected from exploratory soil borings, is generally used. In order to determine the strength parameters, at least 3 identical specimens are required in this test. Having 3 identical specimens, a single stage triaxial test procedure is used. If not, multistage triaxial test procedure is used to eliminate the effects of soil variability in the results. In this case, several confining pressures are applied to the same specimen. Although multistage triaxial tests have been used for soils for a long time, there is still a lack of test results for unbound granular non-traditional materials. This paper presents triaxial test results obtained from a Portuguese unbound granular non-traditional material (named as Inert Steel Aggregate for Construction - ISAC). The triaxial tests were carried out using multistage and single stage techniques. As the results are quite well comparable, it is concluded that it is possible to determine shear strength parameters with just one specimen. Consequently, the research conducted has validated the use of multistage triaxial tests as a reliable and cost-effective alternative to the conventional single stage triaxial test in the mechanical characterization of unbound granular materials.The authors appreciate the financial support of the FCT for this project PCDT/ECM/56952/2004 through the POCI 2010 program and for the cohesion fund FEDER and a doctoral grant within company SFRH/BDE/15661/2007. Acknowledgments are also due to António Cavalheiro, deputy manager of the Seixal Iron Steel Company.info:eu-repo/semantics/publishedVersio

Coordinated Multi-Point MIMO Processing for 4G

The concept of cooperative Multiple-Input-Multiple-Output (MIMO), also referred to as network MIMO, or as Coordinated Multi-Point Transmission (CoMP), was standardized in 3GPP Release 11. The goal of CoMP is to improve the coverage of high data rates and cell-edge throughput, and also to increase system throughput. In this paper we analyze only the latter scenario, using system level simulations in accordance with 3GPP guidelines. It is shown that the use of joint coordinated multipoint transmission achieves additional throughput gains. However, the gains depend on the scheduling type. This paper also indicates that the criterion of fairness is an important parameter when the number of users is high

M.S.W. bottom ash : mechanical characterization for road pavement purposes

Neste trabalho são estudadas as propriedades mecânicas, tais como a rigidez e a resistência, de escórias provenientes da incineração de resíduos sólidos urbanos na incineradora da Valorsul, S.A.. Pretende-se avaliar, sob o ponto de vista geotécnico, a viabilidade de utilização deste material alternativo nas camadas estruturais de pavimentos rodoviários. Neste sentido, são apresentados resultados provenientes dos seguintes ensaios laboratoriais: análise granulométrica; ensaios C.B.R. e ensaio triaxial estático consolidado não drenado com medição das pressões intersticiais. Este estudo pretende contribuir para a valorização das escórias, cuja produção em Portugal, para 2006, se estima em cerca de 293 000 toneladas por ano. Para além de permitir reduzir a quantidade de resíduos a encaminhar para deposição final, o estudo também implica a diminuição da exploração de agregados naturais.In this work the mechanical properties are studied, such as the stiffness and the strength, of bottom ashes from the incineration of municipal solid wastes in the Valorsul, S.A. incinerator. It is intended to evaluate, under the geotechnical point of view, the viability of using this alternative material in the structural layers of road pavements. In this direction, they are presented results proceeding from the following laboratory tests: grain sized analysis; C.B.R. test and undrained consolidated static triaxial test with measurement of the pore water pressures. This study intends to promote MSW bottom ashes, whose production for 2006, in Portugal, is estimated around 293 000 tons per year. Besides allowing reducing the amount of residues to final deposition, the study also implies the reduction of natural aggregate exploration

Precision triaxial tests to determine deformability characteristics

A presente comunicação apresenta várias técnicas de instrumentação local para medição das deformações verticais e radiais de provetes triaxiais cilíndricos e prismáticos, relatando vantagens e inconvenientes das mesmas. Incluem-se nestas técnicas: LVDT (Linear Variable Differential Transformer), LDT (Local Deformation Transducers), efeito de Hall e transdutores piezoeléctricos. Apresentam-se resultados experimentais obtidos sobre um mesmo solo com recurso a estes diferentes tipos de instrumentação na perspectiva de comparar os resultados obtidos, e mostrar a sua influência, muito particularmente, nas curvas de degradação do módulo com o nível de deformação, varrendo o domínio das pequenas às médias deformações. Além disso, ilustram-se também resultados obtidos em diferentes tipos de materiais recorrendo ao uso de LDT’s implementados no Laboratório de Engenharia Civil da Universidade do Minho.This paper presents several techniques of local instrumentation to measure vertical and radial strains in the triaxial cylindrical or prismatic samples. It also refers the advantages or disadvantages of each technique. The techniques includes: LVDT (Linear Variable Differential Transformer), LDT (Local Deformation Transducers), Hall effect and piezoelectric transducers. Experimental results obtained in a same specimen of soil are presented by using these different kinds of instrumentation. The results are compared showing the influence of each kind of instrumentation, in particularly on the degradation curves covering the small to medium strains. Furthermore, results are also illustrated for different types of materials using LDT’s implemented in the Civil Engineering Laboratory of University of Minho.Fundação para a Ciência e Tecnologia - POCI/ECM/61114/2004

Laitiers d’aciérie portugaise : un nouveau géomatériau

The engineering properties of Portuguese processed steel slags (ISACs) are tested to evaluate the appropriateness of their use in transportation infrastructures and geotechnical works. The laboratory results are compared with values specified in the Portuguese standards for natural aggregates and with values found for natural aggregates of various geological origins. The elastic modulus is carefully evaluated in order to compare the two ISACs with two standard base coarse materials (granite aggregate 0/31.5mm and limestone aggregate 0/19mm). All laboratory results show that the national processed steel slags could be used in geotechnical works, and particularly in transportation infrastructures. The two ISACs demonstrated better mechanical properties than the standard, unbound, granular base, coarse materials.Dans cet article sont présentés les résultats d'essai en laboratoire pour évaluer les propriétés des agrégats laitiers d’aciérie Portugaises (ISAC), dans le but de leur utilisation dans des infrastructures de transport et des travaux géotechniques. Les résultats sont comparés aux valeurs indiquées dans les normes portugaises pour les agrégats traditionnels et avec des valeurs trouvées pour les agrégats naturels de différentes origines géologiques. Une attention particulière est faite en termes du module élastique, comparant les deux ISACs, à deux matériaux standards de sous-couches de chaussées (agrégat 0/31.5mm de granite et agrégat 0/19mm de calcaire). Tous les résultats de laboratoire montrent que les laitiers d’aciérie Portugaises pourraient être employés dans les travaux géotechniques, et en particulier dans les infrastructures de transport. On l'a également expérimentalement observé que les deux ISACs ont de meilleures propriétés mécaniques que les matériaux non traités des sous-couches des chaussées.FEDERFundação para a Ciência e a Tecnologia (FCT) - POCI/ECM/56952/2004POCI 201