The City is not a Building

This paper examines the need for a return to a systemic,holistic,and normative approach to designing human settlements that has been neglected with the decline of the Welfare State and the shift to iecemeal,freewheeling,marked-based development during the unprecedented explosion of construction in the last thirty years.The need for a change is brought about by the current ecological and economic crises linked to a high degree to the current belief that the quality of cities emerges from the added-value of individual buildings or through the assemblage of individual structures put together like a building.This paper argues that a city is not like a building.The contemporary city is characterized by an unprecedented number of problems.These problems cannot be handled by individual good will or simple preventive or corrective actions by architects and developers as it has been done the last three decades.What is needed is an overall systemic framework of planning that ① is driven by normative criteria,② can handle a high degree of complexity and interdependence of factors,and ③ can deal with unanticipated,unintended,long-term irreversible environmental impacts that characterize the "third ecology," the inseparable complex of the natural and the human-made.     

A compression-tension concrete damage model, applied to a wind turbine reinforced concrete tower

Structures subjected to cyclic loads show alternative tension-compression stress states; in such a case, even if certain damage (fracture) is reached during the tension cycle, the computational model of the structure should maintain its capacity to withstand subsequent compression based only on the contact effect in the damaged area (opening, closing and reopening of cracks). In order to control this behavior, a phenomenological constitutive model able to consider the contact as a structural limitation is required. From the constitutive point of view, geomaterials have different damage thresholds for tension and compression and, from the structural point of view, it must be ensured that the material damaged in tension still resist compression. In this case, it is accepted that cracks behave as a contact surface at the structural level. To meet the above mentioned phenomenology, a modification of the damage model differentiated in tension and compression proposed by Faria et al. [Faria R, Oliver J, Cervera M. A strain-based plastic viscous-damage model for massive concrete structures. Int J Solids Struct 1998; 35:1533-58] is performed in this paper, considering independent strength thresholds in each of these processes, controlled with two independent discontinuity threshold functions. Also, in this work an elasto-plastic constitutive model is used to represent the behaviour of the steel bars.     

A DETAILED CHEMICAL ANALYSIS OF CHANGES TO BITUMEN PRODUCED BY THE IN SITU COMBUSTION PROCESS AT THE OXYGEN WOLF LAKE PROJECT, ALBERTA PART 1: WHOLE OIL SAMPLES.

The detailed chemical changes in bitumen brought about over a one year period by an in situ combustion process in an oil sands reservoir have been investigated. Relative to a core sample, the fireflood-produced oils exhibited a significant reduction in density and viscosity which began early in the production cycle. This behaviour was correlated with a marked increase in material boiling in the naphtha and middle distillate ranges and a concomitant decrease in the residue cut. The sulfur and nitrogen contents in the produced oils decreased relative to the core sample. A reduction in the acid number of the produced oil samples was coupled with an increase in the oxygen content as the firefiood proceeded. The relationship between these changes and the dynamics of the in situ combustion process are discussed.     

The 2653 polynomial generator and checker

The 2653 PGC device is discussed, which can provide error checking when data is being transferred via a communications link. The device can operate at speeds up to 500, 000 characters per second and because it includes built-in intelligence it can detect special characters and character sequences.     

BIOCHEMICAL ASPECTS OF YEAST FLOCCULATION AND ITS MEASUREMENT: A REVIEW

Factors affecting flocculation of brewing yeast, our current understanding of the process and traditional methods of assessing flocculence are discussed in this review. In spite of extensive study during the last two decades, a number of uncertainties and controversies regarding yeast flocculation still remain. This confusion is due in part to the polyploid or aneuploid nature of most brewing strains studied. At present, uncertainty exists as to the number of genes involved in flocculation as well as the nature and mode of action of the resulting gene products. Another restriction to our investigation of flocculation is the lack of a fundamental and standard test method. Along with a general discussion of yeast flocculation, this report will note conflicting reports concerning the influence of temperature, the effect of metal ions such as magnesium and barium, and the importance of the carboxyl and phosphate groups in yeast cell—cell interactions. As well, past and current methods employed for the assay of brewing yeast flocculation will be discussed.     

COLLOIDAL ASPECTS OF YEAST FLOCCULATION: A REVIEW

In this review, areas of colloid science including the DLVO theory, flocculation kinetics and suspension rheology are outlined and their applicability to the study of yeast flocculation discussed. Specifically, fundamental methods of predicting cell-cell interaction energies, orthokinetic flocculation rates and rheological flow properties of flocculent suspensions are detailed. While the application of these theories to brewing systems is somewhat difficult, they may aid our understanding of brewing yeast flocculation. The limited information available on the colloidal nature and properties of brewing yeast cells is also summarized.