Decompositions of finite projective planes

We consider decompositions of finite projective planes into copies of a particular structure. Our main theorem provides a connection between the existence of a proper projective subplane and the existence of a decomposition into sets of collinear points. Based on this result, we develop a connection between the existence of a projective subplane in a plane II and that of a hitting set in the dual of II.

New cutting-planes for the time-and/or precedence-constrained ATSP and directed VRP

In this paper, we introduce five classes of new valid cutting planes for the precedence-constrained (PC) and/or time-window-constrained (TW) Asymmetric Travelling Salesman Problems (ATSPs) and directed Vehicle Routing Problems (VRPs). We show that all five classes of new inequalities are facet-defining for the directed VRP-TW, under reasonable conditions and the assumption that vehicles are identical. Similar proofs can be developed for the VRP-PC. As ATSP-TW and PC-ATSP can be formulated as directed identical-vehicle VRP-TW and PC-VRP, respectively, this provides a link to study the polyhedral combinatorics for the ATSP-TW and PC-ATSP. The first four classes of these new cutting planes are cycle-breaking inequalities that are lifted from the well-known D^-_k and D⁺_k inequalities (see Grötschel and Padberg in Polyhedral theory. The traveling salesman problem: a guided tour of combinatorial optimization, Wiley, New York, 1985). The last class of new cutting planes, the TW ₂ inequalities, are infeasible-path elimination inequalities. Separation of these constraints will also be discussed. We also present prelimanry numerical results to demonstrate the strengh of these new cutting planes.

When planes fall out of the sky : the war body on screen

I can’t keep my eyes off the war body, even though in the repeated seeing of it I feel nauseous: implicated in, and affected by, its painful coming into being. In this age of the War on Terror, wherever I look, wherever I am directed to look by the all-seeing “vision machines” that “illuminate” our identities (Virilio 1994, 70), the body of the soldier, terrorist, hostage, and victim come into troubling view. These war bodies are real in the ontological and phenomenological sense; they are also metaphoric, simulated, and discursive. In this chapter I will define and explore the complex ways in which these three articulating axis—war, in its militaristic and ideological sense; the screen, in all its multifaceted forms and contexts; and the body, individual and social—conjoin and synthesize, disintegrate and dislocate, in a phantasmagoric but simultaneously desperately real collision of power, desire, and control. My main contention will be that the war body on screen is a “sickening” creation that we have desired into being, so that we may feel, better understand, and be taken over by its terror. This terror of living ultimately helps ensure our docility, a docility required by the late capitalist nation-state; it also reconnect us to our bodies in profoundly moving and potentially challenging ways.

Aplicacao do geoprocessamento no estudo da impermeabilidade urbana

The environmental impact of urbanization due to the surface impervious growing and inadequacy of urban occupation induces to a significant increase of inundation events in every urban center. Hence, this paper focuses the concept of impervious surface as an indicator of environment impact, expressed through the changing of pervious areas in impervious areas by paving cover or building occupation. It is taken as a case study 13 areas pertaining to Canoas City, Rio Grande do Sul – Metropolitan area of Porto Alegre, Brazil. The main goal of the methodology process is to achieve information about types of land cover for studying the association with urban impermeability level. Therefore, the manipulation of municipal digital cartographic base of Canoas City with aerial photographs, through the geoprocessing applied in geographic information system toolbox (GIS), allows this research to produce data about of urban impervious areas generation. These results could help the urban settlement planning to reduce the impervious cover and the hydrological impact in its implementation.

Representação espacial na cognição ambiental urbana : aspectos de uso do solo e presença social

In the present paper different representations of urban character that influence environmental cognition are tested. Two main features involved in urban identity are the functional and social aspects of urban environment. Land use of lots is aggregated into different intensity measures that explore functional characterization of urban spaces. Social presence related to residential use and movement in urban space are also evaluated by intensity and social-economic characteristics. All selected attributes come from normal governmental data bases. Thus, one of the challenges is to transpose/interchange data from different scale units into a unique spatial representation unit, creating a common spatial base in a GIS environment.

Análise da acessibilidade urbana para o planejamento da urbanização de interesse social

An analysis of housing issues in the city of Canela (RS, Brazil) has been made in 2008 as part of the development of the Master Plan for Housing. The present paper deals with one component of this analysis, which is the assessment of urban accessibility for low-income population, and its consequences on the treatment of the problem of current shortage of low-income housing and the future demand from population growth until 2020. A three steps method is applied: (i) urban mobility is assessed and mapped on the basis of the road system and the routes of public transport; (ii) accessibility to different urban services, such as public education and health, recreation, consumption and jobs are measured and mapped considering the location of urban facilities, population distribution divided by income and age, and urban mobility; (iii) one map for urban accessibility is produced as a result of the weighted combination of accessibility to different urban facilities. This final urban accessibility map is then overlayed to empty urban lots with size and land value appropriate to low-income housing, and a simulation of their development over the future has been made. The lots with higher accessibility were selected, and the impact of urban development was assessed on the capacity of education facilities. Based on this study, we made some preliminary suggestions for widening places in some schools, the need for a new education facility (location and size) and the extension of public transport for an area with low accessibility.

Variant selection and intervariant crystallographic planes distribution in martensite in a Ti-6Al-4V alloy

The transformation texture was studied in a Ti-6Al-4V alloy for two microstructures produced through different phase transformation mechanisms (i.e. diffusional vs. displacive). Both microstructures revealed qualitatively similar crystallographic texture characteristics, having two main texture components with Euler angles of (90°, 90°, 0°) and (90°, 30°, 0°). However, the overall α texture strength was considerably weaker in the martensitic structure (i.e. displacive mechanism) compared with the α + β microstructure produced through slow cooling (i.e. diffusional mechanism). The intervariant boundary distribution in martensite mostly revealed five misorientations associated with the Burgers orientation relationship. The five-parameter boundary analysis also showed a very strong interface plane orientation texture, with interfaces terminated mostly on the prismatic planes {hki0}, when misorientation was ignored. The highest intervariant boundary populations belonged to the 63.26°/[10 553 ] and 60°/[112 0] misorientations, with length fractions of 0.38 and 0.3, respectively. The former was terminated on (41 3 0), and the latter was a symmetric tilt boundary, terminated on (1 011). The intervariant plane distribution in martensite was determined more by the constraints of the phase transformation than by the relative interface energies.

Ships, planes and automobiles – the perils and pluses of place - making in an outer Melbourne suburb

Building a new suburb is increasingly seen as creating a “place” as well as a set of houses and neighbourhoods. Developers view “place-making” as a way to differentiate one estate from another and to capture a market segment; planners see the practice as the basis of good master planning. Local governments too support the concept to give residents a sense of pride and identity. While usually seen as a contemporary exercise, imprinted on the blank slate of greenfield sites, the experience of at least one outer suburb suggests that place-making is as much historical as contemporary and may be both a welcome element of a community and a focus of disaffection. The example of Point Cook in Melbourne’s west offers a range of iconic “places” – historical and contemporary markers of identity and difference – which have formed both the basis of local pride but also tension. Thus the RAAF base, Point Cook Homestead and Werribee Mansion long pre-dated the expansion of the city but they have been embraced as centres of pride, historical achievement and as tourist attractions. In contrast, a massive pirate-ship playground built in the centre of a park by a developer as a marker of difference and centre of community attraction was widely appreciated before being burned to the ground! This paper will report on a sample of resident experiences of place-making in outer suburban Melbourne which highlights some of the local complexities of place-making.