Built Conservation and the Unfinished Fabrics of Time

Differentiating between the static impulse to preserve and the more open-ended and imaginative process of conservation, Federica Goffi presents a building as ‘a fabric that, even when complete, is unfinished and open to change’. Associate Professor and Associate Director of Graduate Programs at the Azrieli School of Architecture and Urbanism at Carleton University in Ottawa, Goffi has written widely on the topic of time, particularly taking St Peter's in the Vatican by way of example.     

Upgrading Computational Design

Shajay Bhooshan heads up the computation and design ZHACODE group at Zaha Hadid Architects (ZHA) and is a course master at the Architectural Association Design Research Laboratory (AADRL). Here he argues that Parametricism 2.0 has a vital role to play in the progressing of computational design. Assimilating the exploratory developments of the last 15 years, he asserts how the next phase of Parametricism will enable a further consolidation and evolution of digital practices.     

Global Village Media: Coming Together in the Early 1970s at Whiz Bang Quick City

Felicity D Scott , Associate Professor of Architecture at Columbia University Graduate School of Architecture, Planning and Preservation (GSAPP), describes here the instant city events of the early 1970s. These foreshadowed current global village media practices in what now seems a quaintly material manner: communication between sites involved the physical mailing of videotapes and ‘wire photos’ through the postal service. The sites themselves – in the US and elsewhere – were transformed into ‘instant cities’ through the erection of physical geodesic domes, teepees and inflatables in seas of mud. The true antecedents of today's instant networking, these pioneers embraced the newest technology available at the time and the most innovative forms of temporary architecture.     

Riparian anomie: Reflections on the Los Angeles River

This paper explores the highly urbanized landscape of the Los Angeles River. Direct encounters with the contemporary river are combined with an historical exploration of some of the developments associated with its transformation into a 51-mile concrete drainage channel. It is suggested that the current landscape of the Los Angeles River not only reveals much about the complex relations between nature and culture in southern California but also illustrates how the contemporary city is marked by a schism between technical conceptions of water control and new attempts to combine river management with wider social and ecological objectives.     

Contribution of trace metals from atmospheric deposition to stormwater runoff in a small impervious urban catchment

The contribution of atmospheric deposition to emissions of trace metals in stormwater runoff was investigated by quantifying wet and dry deposition fluxes and stormwater discharges within a small, highly impervious urban catchment in Los Angeles. At the beginning of the dry season in spring 2003, dry deposition measurements of chromium, copper, lead, nickel, and zinc were made monthly for 1 year. Stormwater runoff and wet deposition samples also were collected, and loading estimates of total annual deposition (wet+dry) were compared with annual stormwater loads. Wet deposition contributed 1-10% of the total deposition inside the catchment, indicating the dominance of dry deposition in semi-arid regions such as Los Angeles. Based on the ratio of total deposition to stormwater, atmospheric deposition potentially accounted for as much as 57-100% of the total trace metal loads in stormwater within the study area. Despite potential bias attributable to processes that were not quantified in this study (e.g., resuspension out of the catchment or sequestration within the catchment), these results demonstrate atmospheric deposition represents an important source of trace metals in stormwater to waterbodies near urban centers.     

美国建筑考察之旅

本文对美国城市旧金山、洛杉矶、纽约、华盛顿、拉斯维加斯、圣地亚哥的特色建筑进行描述,揭示了隐藏在建筑表象下的美国多元文化.     

Using a modified CINDER90 routine in MCNPX 2.6.0 for the prediction of helium production in minor actinide targets

Fast reactors containing heterogeneous minor actinide (MA) target rods are now being modeled. When studying transmutation in these rods, helium production from α-decay must be considered since it is produced in substantial quantities. This research utilized an innovative method to calculate gas production by modifying the CINDER90 depletion code used by MCNPX 2.6.0 to include helium production from α-decay. The modified CINDER90 code was verified using the ORIGEN-ARP module of SCALE6. It was tested using the Sodium-Cooled Heterogeneous Innovative Burner Reactor model created at the University of South Carolina. It is recommended that the modified version of the cinder.dat file be distributed in subsequent MCNPX 2.6.0 releases for use in fast reactor calculations using heterogeneous MA target rods since it includes helium production otherwise not available from the current version.     

Limestone Drain Design Parameters for Acid Rock Drainage Mitigation

Abstract.  Limestone drains are an integral component of some of the most efficacious passive systems for the treatment of acid rock drainage (ARD). A critical design parameter for a limestone drain is the mass of limestone that will be required for effective treatment. This in turn depends on the flow rate, limestone dissolution rate, and associated hydraulic detention time necessary to achieve a certain effluent alkalinity for a given design life. Rates of alkalinity generation and limestone dissolution, and the quality of the limestone in terms of weight fraction of CaCO₃ and percentage CaCO₃ available must be known to determine the required mass of limestone. These parameters were experimentally determined for a natural and synthetic suite of ARD waters. The experimental results show that the empirical change in the alkalinity over time cannot simply be modeled as a first-order process. During the initial stage, the concentration increase is extremely fast, giving a linear and steep rise in the alkalinity. Alkalinity concentrations peaked at elapsed times of 90 to 180 minutes and then declined to a nearly constant value. The decline in alkalinity corresponds with a decline in concentrations of dissolved iron and aluminum, implying that the consumption of alkalinity by the hydrolysis of these metals is faster than the rate of alkalinity production by the dissolution of limestone, so that the reaction appears zero order in the early stage and pseudo-first order later. Because the changes in concentration were complex, considerable uncertainty exists in the rate constants for estimating alkalinity concentration. This causes problems in design equations based solely on a limestone dissolution rate that is estimated from alkalinity generation rates. A more applicable design procedure, combining the kinetics of alkalinity production and consumption with the hydraulics and chemical equilibrium of the system, is illustrated. Research was conducted while the first and third authors were with Ecology and Environment, Inc, Dallas, TX, USA;     

Operating Strategy To Meet SWTR Disinfection Regulations At The Los Angeles Aqueduct Filtration Plant

Preozonation facilities were installed at the Los Angeles Aqueduct Filtration Plant originally to enhance coagulation assistance (microflocculation). The Surface Water Treatment Rule will amend this primary purpose to meeting disinfection standards. Additional ozone generation equipment and a revised ozone system operating strategy will be required to accomplish these changed objectives. The topics discussed in this paper are the considerations surrounding the development of a successful, cost-effective operating strategy. The strategy proposed herein was based on data collected between January and July 1991. On-line process monitoring plans and automated system control logic are described.