Densification

Può la densità essere lo strumento analitico di interpretazione dei fenomeni urbani e contemporaneamente un parametro progettuale di prefigurazione dello spazio architettonico? La densità nelle sue diverse accezioni e unità di misura, costituisce un nodo di grande rilevanza per l'interpretazione dei fenomeni urbani e degli spazi architettonici. Incoraggia una riconciliazione dello sguardo quantitativo con quello mirato alla lettura qualitativa, riavvicina discipline disgraziatamente disgiunte nell'attuale pratica, suggerisce mezzi e stili di vita che sono alla base del nostro habitat. Ciò che infatti ha da sempre caratterizzato la città non è solo la sua dimensione ed il numero degli abitanti, ma un secondo fattore fondamentale: la densità appunto, o meglio un valore di densità minimo in grado di produrre divisione del lavoro, varietà di funzioni e attività, complessità della struttura sociale. L'architettura progetta distanze oltrechè volumi, la densità ne è quindi un parametro centrale; l'urbanistica e la progettazione urbana, utilizzando il calcolo della densità come livello minimo di pianificazione, dovranno tendere a configurare in futuro le città, influenzandone gli aspetti non solo numerici, ma anche tipologici, morfologici e spaziali. Riscattato dalla computistica, il fattore densità, si trasforma allora in una variabile urbana in grado di definire la forma attuale della città, divenendone strumento di misurazione e di progetto.

The formation of solid solutions of the type [Ba(HOC2H4OH)4][Ti1−x Gex (OC2H4O)3] as Ba(Ti1−x /Gex )O3 precursors and the phase evolution during thermal decomposition of [Ba(HOC2H4OH)4][Ti0.9Ge0.1(OC2H4O)3] (1) are described herein. The 1,2-ethanediolato complex 1 decomposes above 589 °C to a mixture of BaTiO3 and BaGeO3. A heating rate controlled calcination procedure, up to 730 °C, leads to a nm-sized Ba(Ti0.9/Ge0.1)O3 powder (1a) with a specific surface area of S = 16.9 m2/g, whereas a constant heating rate calcination at 1,000 °C for 2 h yields a powder (1b) of S = 3.0 m2/g. The shrinkage and sintering behaviour of the resulting Ba(Ti0.9/Ge0.1)O3 powder compacts in comparison with nm-sized BaTiO3 powder compacts (2a) has been investigated. A two-step sintering procedure of nm-sized Ba(Ti0.9/Ge0.1)O3 compacts (1a) leads, below 900 °C, to ceramic bodies with a relative density of ≥90%. Furthermore, the cubic ⇆ tetragonal phase transition temperature has been detected by dilatometry, and the temperature dependence of the dielectric constant (relative permittivity) has also been measured.

Torsion extrusion (TE) process was performed successfully for consolidation of commercially pure aluminum powder at 350 °C. It was shown by a specific mechanism that the shear strains applied during consolidation of aluminum powder by the TE process have a considerable effect on the micro-structural shape of the porosities and also their omission efficiency. Density measurements showed that in the TE process a better consolidation, with respect to hot forward extrusion, was accomplished. Tensile and hardness tests results showed superior values for the ultimate tensile strength (UTS) and hardness values in the specimens produced by the TE process.

This paper presents a modification to conventional magnetron sputtering systems. The introduction of a grid in front of the target increases the metal ion ratio. Using OES and observing both Ti neutrals and ions, it was confirmed that the relative ionization could be qualitatively extended with grid-attached magnetron sputtering compared with a conventional magnetron system. On the other hand, the relative ionization of Ar decreased. Our results also show that the Ti films deposited by conventional magnetron exhibit (100) preferred orientation as the bias voltage increased. On the other hand, in the case of the grid-attached magnetron, the Ti films exhibit highly preferred (002) orientation with increasing bias voltage. The experiments clearly demonstrated that a dense Ti film with a smooth, specular reflecting surface can be produced using the grid-attached magnetron with increased Ti ion flux compared to the conventional magnetron.

Australia is the most suburbanised country on earth. The ' Australian Dream' of a house in the suburbs has long reflected the sense of entitlement that urban Australians have to the financial security, private space and amenity that the Dream promises. Since around the turn of the century, governments at every level have been attempting to arrest suburban sprawl for its negative social, environmental and economic impacts. However, neoliberal economic and planning environments have exacerbated regulatory failure, so attempts to create compact cities have done little to provide genuine alternatives to suburban life or address low-quality sprawl in newly built outer suburbs. Unrestrained house price inflation, assisted by an investor-friendly taxation regime, has led to a situation where the housing outcome, the Dream, enjoyed by previous generations is becoming impossible. Overlaying this is an ideological environment that pits the suburbs against the inner city as a battle in the 'culture wars' and serves to obliterate any nuance, diversity or possibility for progressive change into the public debate. Fig. 1: New outer suburban development under construction in Springfield Queensland.

In this study, densification of TiB 2 with the addition of 316L grade stainless steel powder by using the vacuum arc melting (VAM) process was investigated. 316L and TiB 2 powders were mixed in predetermined amounts and pressed to form pellet shaped samples which were later heated in the VAM. Microstructures of the samples were examined by SEM and an optical microscope. It was observed that TiB 2 grains in the samples were wetted by the molten stainless steel phase. Furthermore, it was noted that the sample composition and arc current in the VAM affected the densification behavior of the samples. This kind of a material processing technique can be used to build up a composite layer over different substrates as well as over selected surfaces of machine parts.

Bosa, located in the southwest of Bogota, has around 700,000 inhabitants, is one of the areas most recent urban development in Colombia, in the first decade of the century the population increased by 50% due to contradictory processes between formality and informality; is the only sector in Bogotá with conurbation. This article relates the history of urban planning process of this territory from the seventies, but the urban morphology, the focus is on design and urban management especially in the role of urban actors to transform adverse conditions, product informal development through self-management and citizen participation accompanied by government entities that have prioritized the development of housing projects of the city in the town, attracting private developers to generate increase in land prices and one of the highest rates of densification .

Master Thesis

Housing has always been an urgent question in modern times: how to provide for increasing demand and quickly changing patterns of living.  One of the main issues with it is that the very people who will buy, rent and use housing have mostly have little or no say in the design— or how they would like the house to change over time.

One of the most audacious experiments in modern housing, the Swedish Million Programme, is over 50 years old; these estates are ageing and have become misaligned with modern ways of living, rendering them susceptible to segregated neighbourhoods and neglect, and out of date in terms of energy use. While a new housing shortage looms, the renovations to million program buildings could potentially provide some insights into the housing problem.

The ageing infrastructure of the million programme is an opportunity to reconsider the way we think of housing today.

The million programme was scientifically designed and constructed with state-of-the-art methods in the 60s and 70s, and was an example to the world. Today, the buildings are not up to environmental standards and need refurbishment to improve thermal performance. Also: the particular family sizes that the estates were designed for some decades ago, do not exist in the same proportions today. There is not as much diversity in sizes and types of apartments as are required for today’s different and unpredictable demographic changes.

This thesis proposes a system of extensions to the facades of the buildings that challenge the existing plans and allows newer typologies to be remade from the old buildings. This would necessarily require the participation, conversation and negotiation of the residents, as well as facilitating agencies like the Kommun, Housing companies, Tenants’ Associations, Manufacturers, Construction companies and so on.

Residents have been the most marginalised group of all the parties who come together to make housing; I contend that this is one of the fundamental issues of all housing that are designed with little adaptability and hence are dated with a fixed lifespan, after which changing lives begin to make them redundant. However, a user-driven process and designs that afford adaptation according to changing needs may allow housing to have an inherently longer life, and affect the social cohesion and sense of place of the city as well.

The method is to test architectural strategies to a building of the million programme
 in Umeå, to bring out potentials and possibilities of participation in such a context. The main strategy is a Support and Infill model of incremental addition: the design of fixed infrastructure and of potential changes that may be added onto it. Speculating possible configurations of addition may provide some insight about the benefits and pitfalls of such and similar systems of refurbishment, and of participation.

Perhaps a built environment that is able to change more easily to accommodate people’s changing lives and needs over time produces more energetic, active and livable cities that are more resilient to change and unpredictability that is characteristic of our world today.

The sintering kinetics and microstructural evolution of alumina tubes (∼17 mm length, ∼9 mm inner diameter, and ∼11 mm outer diameter) were studied by conventional and microwave heating at 2.45 GHz. Temperature during microwave heating was measured with an infrared pyrometer and was calibrated to ±10°C. With no hold at sintering temperature, microwave-sintered samples reached 95% density at 1350°C versus 1600°C for conventionally heated samples. The activation energy for microwave sintering was 85 ± 10 kJ/mol, whereas the activation energy for conventionally sintered samples was 520 ± 14 kJ/mol. Despite the difference in temperature, grains grew from ∼1.0 μm at 86% density to ∼2.6 μm at 98% density for both conventionally sintered and microwave-sintered samples. The grain size/density trajectory was independent of the heating source. It is concluded that the enhanced densification with microwave heating is not a consequence of fast-firing and therefore is not a result in the change in the relative rates of surface and grain boundary diffusion in the presence of microwave energy.

Torrefaction is a process to convert diverse lignocellulosic biomass feedstocks into an energy dense homogeneous solid, a pretreatment for subsequent thermochemical conversion. Loblolly pine was treated by wet torrefaction (hot compressed water, 200–260°C) and dry torrefaction (nitrogen, 250–300°C), with mass yield of solid product ranging between 57 and 89%, and energy densification to 108–136% of the original feedstock. The solid product has been characterized, including proximate analysis, fiber analysis, ultimate analysis, and equilibrium moisture. In both dry and wet torrefaction, increasing temperature results in decreased mass yield and increased energy densification, and results in a solid with increased carbon content, decreased oxygen content, and decreased volatiles. The biomass is transformed into a fuel similar to a low-rank coal. Generally, the wet torrefaction process produces a solid with greater energy density than dry torrefaction, with the same mass yield. The fiber analysis indicates that hemicellulose is quickly removed during wet torrefaction, and the solid product contains substantial quantities of aqueous soluble compounds. The equilibrium moisture content of solids produced by both processes is somewhat decreased from that of the biomass feedstock, indicating a hydrophobic solid suitable for storage and transportation. © 2009 American Institute of Chemical Engineers Environ Prog, 2009

Proyectar vivienda también implica involucrarse en la complejidad de un megaproyecto. El éxito se basa en la mezcla social y de usos, para que repercuta en la construcción de una ciudad más heterogénea, múltiple, equitativa, y que garantice su sostenibilidad en el largo plazo.

The aim of gravity thickening processes is to increase the solids concentration of particulate slurries. Gravity thickening depends on the difference in densities between the solid and liquid phases. The solids settle to a more concentrated slurry zone towards the underflow at the thickener base, while relatively solids free liquid rises to the overflow at the top. Predictive modelling of gravity thickener performance from experimentally determined material properties has been shown to under predict throughput by a factor of up to 100. One phenomenon proposed to account for some of this discrepancy is aggregate densification, whereby aggregates compact and become smaller when subjected to shear forces in the thickening process. As the aggregates decrease in size, through densification, the tortuosities around the aggregates will decrease, thus leading to a significant net decrease in the resistance to fluid flow. Dewatering theory has been applied to predict the impact of aggregate densification on the material properties that describe dewatering. The anticipated decrease in aggregate size and associated increase in the density of these aggregates is expected to increase the settling rate. It is further expected on this basis that the material will settle to higher solids concentrations. The impact of these changes on gravity thickening performance is modelled and predicted to be significant.