124 research outputs found

    Historic rammed earth structures in Spain : construction techniques and a preliminary classification.

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    Conservation and repair of historic rammed earth sites should only be undertaken if there is a good understanding of the consequences of any intervention technique. Until recently there has been little interest in the characterisation of historic rammed earth construction, yet it is only with this understanding that successful conservation strategies can be adopted. A survey of around 60 historic rammed earth sites in Spain constructed between 967AD and 1837AD has recently been undertaken. While all the sites are built primarily in rammed earth, the construction techniques and state of repair vary greatly. The high density of historic rammed earth structures in the Iberian peninsula is likely due to the Muslim presence there from the 8th century onwards. Initial expansion, a period of civil war and eventual defeat by Christians led to the construction of a large number of fortifications, many constructed in rammed earth. A famous example is the Alhambra at Granada, but there are hundreds of smaller sites throughout Spain. By the end of the 15th century Christians had replaced Muslims through most of Spain, but rammed earth continued to be used in both vernacular and monumental architecture. Examples of historic construction techniques are presented and common features of historic rammed earth construction are identified. A classification is outlined and a clear development of the rammed earth technique is observed

    Role of energy and exergy analyses in performance improvement and development of advanced and sustainable energy systems

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    Paper presented to the 10th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Florida, 14-16 July 2014.There is a growing interest on advanced and sustainable energy systems worldwide. Natural gas, biomass and coal based power generation and integrated energy systems are receiving attention to meet the growing energy demand with reduced pollutants and greenhouse gas emissions. Integrated coal and biomass gasification combined cycle power generation systems are also in use due to increased power generation efficiency and reduced emissions. Natural gas and biomass supplementary firing and hybrid power generation systems are also receiving attention to reduce greenhouse gas emissions. Solar, wind and biomass based power generation systems are also growing due to their sustainable nature. The present paper reviews natural gas, biomass and coal based advanced and sustainable energy systems. The exergy analysis for energy systems is receiving attention due to the ability to analyze a power generation system from quality point of view. The role of exergy analysis for natural gas, coal and biomass power generation systems and the role of operating parameters on performance improvement is also presented.cf201

    Compressive Strength of Novel Alkali-Activated Stabilized Earth Materials Incorporating Solid Wastes

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    The research presented in this paper is aimed at developing novel alternative sustainable stabilized earth materials for use in load-bearing affordable housing construction. Prototype-stabilized earth materials have been produced in the laboratory, incorporating a range of solid wastes, including aggregates derived from construction and demolition waste as well as industrial processes. The earth construction materials were stabilized with either portland cement, Portland cement and lime, or through alkali activation. Experimental results for compressive strength are reported, together with findings from a comparative life cycle inventory analysis. Construction and demolition waste shows promise as a potential aggregate for stabilized earth construction. The use of processed ground blast furnace slag together with fly ash is also promising for the development of alkali-activated stabilization.</p

    Compressive strength of novel alkali activated stabilised earth

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    The research presented in this paper is aimed at developing novel alternative sustainable stabilized earth materials for use in load-bearing affordable housing construction. Prototype-stabilized earth materials have been produced in the laboratory, incorporating a range of solid wastes, including aggregates derived from construction and demolition waste as well as industrial processes. The earth construction materials were stabilized with either portland cement, Portland cement and lime, or through alkali activation. Experimental results for compressive strength are reported, together with findings from a comparative life cycle inventory analysis. Construction and demolition waste shows promise as a potential aggregate for stabilized earth construction. The use of processed ground blast furnace slag together with fly ash is also promising for the development of alkali-activated stabilization.</p

    Livelihood gains and ecological costs of NTFP dependence: assessing the roles of dependence, ecological knowledge and market structure in three contrasting human and ecological settings in south India

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    Non-timber forest products (NTFPs) constitute the single largest determinant of livelihoods for scores of forest fringe communities and poor people in the tropics. In India over 50 million people are believed to be directly dependent upon NTFPs for their subsistence. However, such human dependence on NTFPs for livelihood gains (win) has most frequently been at a certain ecological cost (lose). If livelihoods are to be maintained, the existing ‘win-lose’ settings have to be steered to a ‘win-win’ mode, otherwise, there could be severe erosion of the biological resources and loss of livelihoods (‘lose-lose’). Examining the dependence of forest fringe communities on NTFPs at three sites in south India with contrasting human and ecological settings, three key factors (extent of dependence on NTFPs, indigenous ecological knowledge and market organization) are likely to constrain reaching the win-win situation. How these factors shape the ecological cost of harvesting NTFPs at the three sites is examined. Within the parameter space of these factors, it is possible to predict outcomes and associations that will conform to win-win or win-lose situations. Empirical data derived from the three study sites demonstrate the causality of the observed associations. The key for long-term livelihood gains lies in reducing the ecological cost. Certain interventions and recommendations that could optimize the balance between livelihood gains and ecological cost are proposed

    Panorama of neoplasms of upper GI tract: a 5 year research study

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    Background: The diseases of the gastrointestinal tract (GIT) are the most common and leading cause of morbidity and mortality than the disorders of any other systems of the body. Gastrointestinal (GI) tract tumors are one of the most common cancers accounting for 11% of all cancers. Among these tumors, upper gastrointestinal tract malignancies are quite aggressive with a dismal prognosis. Malignant tumors are most common than benign. The most common carcinoma of the esophagus is Squamous cell carcinoma (SCC). Incidence of SCC is less than 5 per 100,000 populations in males and 1 per 100,000 populations in females. Gastric cancer was the second most common cancer in the World and 60% of them occurred in developing countries. The most common carcinoma of the Stomach is Adenocarcinoma.Aim &amp; Objectives: To study the spectrum of neoplastic lesions of the upper gastrointestinal tract by the examination of endoscopic biopsies and surgically resected specimens. To determine the degree of severity of the malignancies by assessing the depth of invasion, Lymph nodal &amp; Omental spread.Methods: The present study is both retrospective &amp; prospective study for a period of 5 years from January 2007 to December 2011. The sample size includes all the endoscopic biopsies &amp; surgically resected specimens of gastrointestinal tract received at Department of Pathology, S.V. Medical College, Tirupati. The study also obtained clearance from the ethical committee of the institution. The biopsy specimens thus obtained were fixed in 10% buffered neutral formalin. The sections were stained routinely with H &amp; E. Special stains and IHC done wherever necessary.Results: we have received 120 specimens regarding the upper gastrointestinal system. Among these 120 specimens, 71 specimens were endoscopic biopsies &amp; 49 specimens were surgically resected specimens. Out of 71 Endoscopic biopsies 28 biopsies were malignant among which 2 was esophagus and 26 were stomach. Out of 49 surgically resected specimens 1 was benign and 32 were malignant tumors. Out of 59 neoplasms of stomach there were single cases each of Sub mucosal Lipoma, Malignant lymphoma, GIST &amp; 56 cases of Adenocarcinoma &amp; its variants were noted.Conclusion: Most of the neoplasms are of stomach (97%). All the neoplasms are malignant except one benign lesion sub mucous lipoma of stomach. Most of the neoplasms of stomach were Adenocarcinoma (96.5%). Both tumors of esophagus were squamous cell carcinoma occurred after 50 years of age.

    A dc-link voltage stability analysis technique for hybrid five-phase open-end winding drives

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    This paper studies the dc-link voltage stability for a hybrid five-phase open-end winding (OeW) drive operating under carrier based (CB) pulse-width modulation (PWM). The drive consists of a five-phase induction machine, supplied using one three-level and one two-level voltage source inverter (VSI). This configuration is analysed for the case of isolated dc-link rails, while dc-link voltage ratio is considered as an additional degree of freedom. It is demonstrated that different dc-link voltage ratios lead to the different overall number of voltage levels across stator windings. Modulation strategies are investigated and their performances are analysed from the dc-link voltages stability point of view. An analytical method for dc-link voltage stability analysis is presented. Results show that the four-level configuration always leads to stable dc-link voltages, regardless of the modulation strategy. On the other hand, if six-level configuration is combined with modulation strategies that lead to an optimal harmonic performance, not all dc-link capacitor voltages will be in balance depending on the operating conditions

    Enhancement of the magnetic anisotropy of nanometer-sized Co clusters: influence of the surface and of the inter-particle interactions

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    We study the magnetic properties of spherical Co clusters with diameters between 0.8 nm and 5.4 nm (25 to 7500$ atoms) prepared by sequential sputtering of Co and Al2O3. The particle size distribution has been determined from the equilibrium susceptibility and magnetization data and it is compared to previous structural characterizations. The distribution of activation energies was independently obtained from a scaling plot of the ac susceptibility. Combining these two distributions we have accurately determined the effective anisotropy constant Keff. We find that Keff is enhanced with respect to the bulk value and that it is dominated by a strong anisotropy induced at the surface of the clusters. Interactions between the magnetic moments of adjacent layers are shown to increase the effective activation energy barrier for the reversal of the magnetic moments. Finally, this reversal is shown to proceed classically down to the lowest temperature investigated (1.8 K).Comment: 13 figures submitted to Phys. Rev.

    Isolation and evolutionary analysis of Australasian topotype of bluetongue virus serotype 4 from India

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    Bluetongue (BT) is a Culicoides-borne disease caused by several serotypes of bluetongue virus (BTV). Similar to other insect-borne viral diseases, distribution of BT is limited to distribution of Culicoides species competent to transmit BTV. In the tropics, vector activity is almost year long, and hence, the disease is endemic, with the circulation of several serotypes of BTV, whereas in temperate areas, seasonal incursions of a limited number of serotypes of BTV from neighbouring tropical areas are observed. Although BTV is endemic in all the three major tropical regions (parts of Africa, America and Asia) of the world, the distribution of serotypes is not alike. Apart from serological diversity, geography-based diversity of BTV genome has been observed, and this is the basis for proposal of topotypes. However, evolution of these topotypes is not well understood. In this study, we report the isolation and characterization of several BTV-4 isolates from India. These isolates are distinct from BTV-4 isolates from other geographical regions. Analysis of available BTV seg-2 sequences indicated that the Australasian BTV-4 diverged from African viruses around 3,500 years ago, whereas the American viruses diverged relatively recently (1,684 CE). Unlike Australasia and America, BTV-4 strains of the Mediterranean area evolved through several independent incursions. We speculate that independent evolution of BTV in different geographical areas over long periods of time might have led to the diversity observed in the current virus population
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