Finding Lost Space: Theories of Urban Design

The problem of "lost space," or the inadequate use of space, afflicts most urban centers today. The automobile, the effects of the Modern Movement in architectural design, urban-renewal and zoning policies, the dominance of private over public interests, as well as changes in land use in the inner city have resulted in the loss of values and meanings that were traditionally associated with urban open space. This text offers a comprehensive and systematic examination of the crisis of the contemporary city and the means by which this crisis can be addressed. Finding Lost Space traces leading urban spatial design theories that have emerged over the past eighty years: the principles of Sitte and Howard; the impact of and reactions to the Functionalist movement; and designs developed by Team 10, Robert Venturi, the Krier brothers, and Fumihiko Maki, to name a few. In addition to discussions of historic precedents, contemporary approaches to urban spatial design are explored. Detailed case studies of Boston, Massachusetts; Washington, D.C.; Goteborg, Sweden; and the Byker area of Newcastle, England demonstrate the need for an integrated design approach--one that considers figure-ground, linkage, and place theories of urban spatial design. These theories and their individual strengths and weaknesses are defined and applied in the case studies, demonstrating how well they operate in different contexts. This text will prove invaluable for students and professionals in the fields of architecture, landscape architecture, and city planning. Finding Lost Space is going to be a primary text for the urban designers of the next generation. It is the first book in the field to absorb the lessons of the postmodern reaction, including the work of the Krier brothers and many others, and to integrate these into a coherent theory and set of design guidelines. Without polemics, Roger Trancik addresses the biggest issue in architecture and urbanism today: how can we regain in our shattered cities a public realm that is made of firmly shaped, coherently linked, humanly meaningful urban spaces? Robert Campbell, AIA Architect and architecture critic Boston Globe

Metals Production Requirements for Rapid Photovoltaics Deployment

If global photovoltaics (PV) deployment grows rapidly, the required input materials need to be supplied at an increasing rate. In this paper, we quantify the effect of PV deployment levels on the scale of metals production. For example, we find that if cadmium telluride {copper indium gallium diselenide} PV accounts for more than 3% {10%} of electricity generation by 2030, the required growth rates for the production of indium and tellurium would exceed historically-observed production growth rates for a large set of metals. In contrast, even if crystalline silicon PV supplies all electricity in 2030, the required silicon production growth rate would fall within the historical range. More generally, this paper highlights possible constraints to the rate of scaling up metals production for some PV technologies, and outlines an approach to assessing projected metals growth requirements against an ensemble of past growth rates from across the metals production sector. The framework developed in this paper may be useful for evaluating the scalability of a wide range of materials and devices, to inform technology development in the laboratory, as well as public and private research investment

Reigoldswil: Eine anthropologische Untersuchung zweier Gräberfelder aus dem 7.-13. Jh

Die Gemeinde Reigoldswil liegt im nordwestlichen Jurabogen der Nordwestschweiz auf einer Höhe von 420–545 m. ü. M. Diese mittleren Höhenlagen wurden nach dem Zusammenbruch des römischen Reiches erst wieder ab dem 7. Jh. besiedelt. Umso erstaunlicher ist es, dass in Reigoldswil gleich zwei Gräberfelder dieser Zeitstellung angelegt worden sind, die auch archäologisch untersucht werden konnten. Zur anthropologischen Analyse gelangten aus dem Gräberfeld Bergli 97 Individuen und aus dem Gräberfeld Kilchli 198 Individuen aus insgesamt 156 Gräbern. Die Radiokarbondatierung (n = 46) erlaubt eine zeitliche Eingrenzung zwischen dem 7. und 13. Jh. für den Grossteil der Gräber, wobei im Kilchli die Bestatteten in zwei Gruppen (A und B) eingeteilt werden konnten, die sich aus Bestattungen vor und nach 1000 n. Chr. zusammensetzen. Das Gräberfeld Bergli wurde nach 900 n. Chr. wohl nicht mehr als Bestattungsplatz genutzt. Die Untersuchung der menschlichen Reste erfolgte morphologisch mit Hilfe etablierter Methoden (Grupe et al., 2015). Die Geschlechts- und Sterbealtersbestimmung, die Körperhöhen sowie allfällige krankhafte Veränderungen an den Knochen wurden aufgenommen. Gleichzeitig wurden 171 Knochen für die Analyse der stabilen Isotopenverhältnisse von Kohlenstoff, Stickstoff, Schwefel und Wasserstoff beprobt. Die Kollagenextraktion erfolgte nach den Methoden von Longin und Ambrose (Longin, 1971; Ambrose, 1990). Anhand der morphologischen Untersuchungen konnte festgestellt werden, dass in beiden Gräberfeldern doppelt so viele Männer bestattet wurden wie Frauen. Die Altersverteilung der verstorbenen Individuen unterschied sich sehr stark zwischen den Gräberfeldern. Im Kilchli konnte für die beiden Stichproben A und B ein hoher Anteil an Kinderbestattungen, insbesondere an Säuglings- und Kleinkinderbestattungen belegt werden. Die Frauen und Männer dieser Fundstelle wurden tendenziell auch älter als im Bergli. Die Körperhöhen der Individuen aus der Teilgruppe Kilchli A zählten zu den höchsten in Reigoldswil, sowohl für die Frauen wie auch für die Männer. Die Stressmarker Cribra orbitalia und porotische Hyperostose wurden gleich häufig an den Kindern der Stichproben A und B angetroffen wohingengen periostale Reaktionen vor allem an den Langknochen aus der Teilgruppe B festgestellt wurden. Die Gelenkbelastungen der Männer aus dem Bergli und Kilchli A waren sich sehr ähnlich und seitlich ausgewogen, wohingegen die Männer aus dem Kilchli B ein einseitiges Belastungsmuster zeigten. Das Gelenkbelastungsmuster der Bergli-Frauen ähnelte demjenigen der Frauen aus Kilchli B. Somit übten die Frauen der Gruppe Kilchli A andersartige Bewegungsabläufe aus. In allen drei Stichproben der Frauen waren einseitige Belastungen feststellbar. Die Kariesintensität war relativ hoch, wobei die Bergli-Individuen am geringsten und diejenigen der Teilgruppe Kilchli B am höchsten betroffen waren. Die Individuen aus dem Gräberfeld Bergli wiesen doppelt so viele periapikale Prozesse auf. Die Ernährungsstrategien konnten über die Analyse der Kohlenstoff- und Stickstoffisotopenverhältnisse untersucht werden. Die Unterschiede zwischen den erwachsenen Individuen beider Fundstellen und zwischen den Teilgruppen waren minim und wenig signifikant ausgebildet. Der Trophiestufeneffekt musste für alle drei Stichproben als gering angesprochen werden. Unterschiede in den Schwefelisotopenverhältnissen zwischen den Männern und Frauen wie auch den Kindern waren signifikant in den Testgruppen Kilchli A und B. Die Wasserstoffisotope aller Individuen deckten ein grosses Spektrum ab und wiesen einem Teil der Individuen beider Gräberfelder eine Herkunft rheinabwärts aus dem Oberen Rheingraben zu. Die Untersuchung des menschlichen Skelettmaterials lieferte einige Hinweise darauf, dass im Kilchli während des 8. Jh., wie von der Archäologie postuliert, eine neue Welle der Besiedlung stattfand. Zwei der frühesten Bestattungen zeigen hier noch lokale Wasserstoffisotopenverhältnisse, die bei den später datierten Individuen nicht mehr angetroffen werden konnten. Die These, dass sich im Kilchli vor der Jahrtausendwende eine wohlhabende Familie niederliess, konnte aufgrund der anthropologischen Untersuchung nicht verworfen werden. Einige Unterschiede zwischen den beiden Gruppen Bergli und Kilchli A, wie in der Körperhöhe oder im Gesundheitszustand, könnten für eine soziale Differenzierung sprechen. Sie sind aber statistisch nicht signifikant. In der geographischen Herkunft scheinen sich die Individuen beider Gräberfelder kaum zu unterscheiden

Re-examining rates of lithium-ion battery technology improvement and cost decline

Lithium-ion technologies are increasingly employed to electrify transportation and provide stationary energy storage for electrical grids, and as such their development has garnered much attention. However, their deployment is still relatively limited, and their broader adoption will depend on their potential for cost reduction and performance improvement. Understanding this potential can inform critical climate change mitigation strategies, including public policies and technology development efforts. However, many existing models of past cost decline, which often serve as starting points for forecasting models, rely on limited data series and measures of technological progress. Here we systematically collect, harmonize, and combine various data series of price, market size, research and development, and performance of lithium-ion technologies. We then develop representative series for these measures and employ performance curve models to estimate improvement rates. We also develop a method to incorporate additional performance characteristics into these models, including energy density and specific energy performance metrics. When energy density is incorporated into the definition of service provided by a lithium-ion cell, estimated technological improvement rates increase considerably, suggesting that previously reported improvement rates might underestimate the rate of lithium-ion technologies' change. Moreover, our estimates suggest the degree to which lithium-ion technologies' price decline might have been limited by performance requirements other than cost per energy capacity. These rates also suggest that battery technologies developed for stationary applications, where restrictions on volume and mass are relaxed, might achieve faster cost declines, though engineering-based mechanistic cost modeling is required to further characterize this potential.Comment: 37 pages, 11 figure

Historical costs of coal-fired electricity and implications for the future

We study the cost of coal-fired electricity in the United States between 1882 and 2006 by decomposing it in terms of the price of coal, transportation cost, energy density, thermal efficiency, plant construction cost, interest rate, capacity factor, and operations and maintenance cost. The dominant determinants of cost have been the price of coal and plant construction cost. The price of coal appears to fluctuate more or less randomly while the construction cost follows long-term trends, decreasing from 1902 to 1970, increasing from 1970 to 1990, and leveling off since then. Our analysis emphasizes the importance of using long time series and comparing electricity generation technologies using decomposed total costs, rather than costs of single components like capital. By taking this approach we find that the history of coal-fired electricity suggests there is a fluctuating floor to its future costs, which is determined by coal prices. Even if construction costs resumed a decreasing trend, the cost of coal-based electricity would drop for a while but eventually be determined by the price of coal, which fluctuates while showing no long-term trend.National Science Foundation (U.S.) (NSF Grant SBE0738187

Methane mitigation timelines to inform energy technology evaluation

Energy technologies emitting differing proportions of methane (CH[subscript 4]) and carbon dioxide (CO[subscript 2]) vary significantly in their relative climate impacts over time, due to the distinct atmospheric lifetimes and radiative efficiencies of the two gases. Standard technology comparisons using the global warming potential (GWP) with a fixed time horizon do not account for the timing of emissions in relation to climate policy goals. Here we develop a portfolio optimization model that incorporates changes in technology impacts based on the temporal proximity of emissions to a radiative forcing (RF) stabilization target. An optimal portfolio, maximizing allowed energy consumption while meeting the RF target, is obtained by year-wise minimization of the marginal RF impact in an intended stabilization year. The optimal portfolio calls for using certain higher-CH[subscript 4]-emitting technologies prior to an optimal switching year, followed by CH[subscript 4]-light technologies as the stabilization year approaches. We apply the model to evaluate transportation technology pairs and find that accounting for dynamic emissions impacts, in place of using the static GWP, can result in CH[subscript 4] mitigation timelines and technology transitions that allow for significantly greater energy consumption while meeting a climate policy target. The results can inform the forward-looking evaluation of energy technologies by engineers, private investors, and policy makers.MIT Energy InitiativeMassachusetts Institute of Technology. Charles E. Reed Faculty Initiative FundNew England University Transportation Center (DOT Grant DTRT12-G-UTC01)National Science Foundation (U.S.). Graduate Research Fellowship (Grant 1122374

Growth in metals production for rapid photovoltaics deployment

If global photovoltaics (PV) deployment grows rapidly, the required input materials need to be supplied at an increasing rate. We quantify the effect of PV deployment levels on the scale of annual metals production. If a thin-film PV technology accounts for 25% of electricity generation in 2030, the annual production of thin-film PV metals would need to grow at rates of 15-30% per year. These rates exceed those observed historically for a wide range of metals. In contrast, for the same level of crystalline silicon PV deployment, the required silicon production growth rate falls within the historical range.United States. Dept. of Energy (Grant DE-EE0006131

Personal Vehicles Evaluated against Climate Change Mitigation Targets

Meeting global climate change mitigation goals will likely require that transportation-related greenhouse gas emissions begin to decline within the next two decades and then continue to fall. A variety of vehicle technologies and fuels are commercially available to consumers today that can reduce the emissions of the transportation sector. Yet what are the best options, and do any suffice to meet climate policy targets? Here, we examine the costs and carbon intensities of 125 light-duty vehicle models on the U.S. market today and evaluate these models against U.S. emission-reduction targets for 2030, 2040, and 2050 that are compatible with the goal of limiting mean global temperature rise to 2 °C above preindustrial levels. Our results show that consumers are not required to pay more for a low-carbon-emitting vehicle. Across the diverse set of vehicle models and powertrain technologies examined, a clean vehicle is usually a low-cost vehicle. Although the average carbon intensity of vehicles sold in 2014 exceeds the climate target for 2030 by more than 50%, we find that most hybrid and battery electric vehicles available today meet this target. By 2050, only electric vehicles supplied with almost completely carbon-free electric power are expected to meet climate-policy targets

Statistical Basis for Predicting Technological Progress

Forecasting technological progress is of great interest to engineers, policy makers, and private investors. Several models have been proposed for predicting technological improvement, but how well do these models perform? An early hypothesis made by Theodore Wright in 1936 is that cost decreases as a power law of cumulative production. An alternative hypothesis is Moore's law, which can be generalized to say that technologies improve exponentially with time. Other alternatives were proposed by Goddard, Sinclair et al., and Nordhaus. These hypotheses have not previously been rigorously tested. Using a new database on the cost and production of 62 different technologies, which is the most expansive of its kind, we test the ability of six different postulated laws to predict future costs. Our approach involves hindcasting and developing a statistical model to rank the performance of the postulated laws. Wright's law produces the best forecasts, but Moore's law is not far behind. We discover a previously unobserved regularity that production tends to increase exponentially. A combination of an exponential decrease in cost and an exponential increase in production would make Moore's law and Wright's law indistinguishable, as originally pointed out by Sahal. We show for the first time that these regularities are observed in data to such a degree that the performance of these two laws is nearly tied. Our results show that technological progress is forecastable, with the square root of the logarithmic error growing linearly with the forecasting horizon at a typical rate of 2.5% per year. These results have implications for theories of technological change, and assessments of candidate technologies and policies for climate change mitigation