110 research outputs found
Strategic decision modeling in Brownfield redevelopment
De ruimtelijke planning en het herstructureringsproces van bedrijventerreinen zijn onlangs aan enkele belangrijke veranderingen onderhevig geweest. Ten eerste is de omvang van de ruimtelijke herstructureringsprojecten toegenomen. Ten tweede zijn de traditionele lineaire planningsprocessen vervangen door publiek-private samenwerkingen waarbinnen de rollen en de onderlinge afhankelijkheid van ontwikkelaars en overheidsorganen gewijzigd zijn. Binnen deze nieuwe kaders is de herstructurering van brownfields veelal problematisch; er treden veel conflicten op tijdens planprocessen. In dit onderzoek wordt beargumenteerd dat het gebrek aan consensus onder betrokken stakeholders een belangrijke oorzaak is van de optredende stagnatie binnen brownfield herstructureringsprocessen. Het uiteindelijke doel van dit onderzoek is het voorspellen en analyseren van het optreden van conflicten in herstructureringsprocessen, alsmede het doen van aanbevelingen over optimale publiek-private samenwerkingsovereenkomsten voor de herstructurering van brownfields. Om dit doel te verwezenlijken is er een onderzoekskader opgesteld, welke is gericht op het specificeren en analyseren van: (1) de attributen van een brownfield; (2) de voorkeuren van de groepen van actoren; en (3) de kenmerken in het onderhandelingsproces tussen de twee groepen van actoren. Voor het verzamelen van noodzakelijke data zijn er twee online enquêtes gehouden. In beide gevallen waren de geënquêteerden experts binnen een specifieke tak van gebiedsontwikkeling. Voor dit onderzoek zijn verschillende methoden gebruikt. Ten eerste is de Fuzzy Delphi methode gebruikt om brownfield attributen te structureren en te prioriteren. Stated Choice experimenten verschaffen vervolgens het inzicht in de individuele voorkeuren van verschillende actor-groepen. Deze resulterende nutsfuncties zijn uiteindelijk gebruikt als de input voor de analyse van multi-actor besluitvorming, waarvoor de methode Game Theory is gebruikt. De resultaten van het besluitvormingsproces hangen niet alleen af van een individuele keuze maar ze bevatten ook de invloed van de keuzes van een tegenspeler. Het vinden van mogelijke consensusrijke strategieën in de onderhandelingen over de herstructurering van brownfields is het doel van deze laatste stap. Tot op heden is er weinig onderzoek verricht naar de ontwikkeling van besluitvormingsmodellen waarin systematisch de kenmerken van de brownfieldterreinen en de herstructureringsplannen verbonden wordt met het gedrag van de betrokken actoren; een dergelijke verbinding kan inzicht geven in mogelijke bronnen van conflicten. Dit onderzoek draagt bij aan de ontwikkeling van modellen waarin de interactie tussen verschillende actoren binnen een complex probleemgebied wordt geanalyseerd. De resultaten van dit onderzoek ondersteunen besluitvormers en procesmanagers bij het vinden van een optimale overeenkomst in de publiek-private onderhandelingen omtrent de herstructurering van brownfields
Building a CCD Spectrograph for Educational or Amateur Astronomy
We discuss the design of an inexpensive, high-throughput CCD spectrograph for
a small telescope. By using optical fibers to carry the light from the
telescope focus to a table-top spectrograph, one can minimize the weight
carried by the telescope and simplify the spectrograph design. We recently
employed this approach in the construction of IntroSpec, an instrument built
for the 16-inch Knowles Telescope on the Harvard College campus.Comment: 17 pages including 7 figures, PASP, accepted (higher resolution
figures at http://cfa-www.harvard.edu/~sheila/introspec.ps.gz
Stagnation in Brownfield redevelopment
Purpose of this paper is two-folded. At first it explains the major problems that are causing stagnation in brownfield redevelopment. In addition, these problems given the context of the present multi-actor built environment are becoming more complex to observe. Therefore, this paper suggests also a prospective decisionmaking approach that is the most appropriate to observe and react on the given stagnation problems. Such an approach should be regarded as prescriptive-interactive decision-making approach, a barely established branch. This approach should offer models that have prescriptive as well as an interactive component enabling them to successfully cope with the multi-actor environment. Overall, this paper provides up-to-date insight on the brownfield stagnation by gradually introducing the nowadays major problems and offers a prospective decision-making approach how these problems could be tackled
Climatic cycles recorded in the Middle Eocene hemipelagites from a Dinaric foreland basin of Istria (Croatia)
Middle Eocene hemipelagic marls from the Pazin-Trieste Basin, a foreland basin of the Croatian Dinarides, display repetitive alternations of two types of marls with different resistance to weathering. This study focuses on the chemical composition, stable isotopes, and palynomorph content of these marls in order to better understand the nature of their cyclic deposition and to identify possible paleoenvironmental drivers responsible for their formation. The less resistant marls (LRM) have consistently lower carbonate content, lower δ18O and δ13C values, and more abundant dinoflagellate cysts than the more resistant marls (MRM). We interpret these differences between the two marl types to be a result of climatic variations, likely related to Milankovitch oscillations. Periods with wetter climate, associated with increased continental runoff, detrital and nutrient influx produced the LRM. Higher nutrient supply sparked higher dinoflagellate productivity during these times, while reduced salinity and stratification of the water column may have hampered the productivity of calcareous nannoplankton and/or planktonic foraminifera. In contrast, the MRM formed during dryer periods which favoured higher carbonate accumulation rates. This study provides new information about the sedimentary record of short-scale climate variations reflected in wet-dry cycles during an overall warm, greenhouse Earth
Increasing the benefits of stadiums for a municipality through sustainable development : a case study of Stadion Feijenoord
Almost all Dutch municipalities hosting a professional football club are owner of the stadium. The uncertainty of the indirect social and economic benefits of a stadium together with often unhealthy financial situations of professional sports club can result in the vacancy of the stadium. Thus, unmonitored decisions bring along irresponsible high financial risks for these municipalities in relation to the gained benefits. With sustainable (re)development these stadiums can become more beneficial for both the municipality and the main user, a sport club itself. A questionnaire among 31 City Councillors of the Dutch cities Amsterdam, Rotterdam, Eindhoven and Enschede showed that limited financial risks and attracting companies are the most important criteria for public investments in stadium projects. Specific aspects related to sustainability had a lower impact, but the sustainability of the whole project, including long-term planning for example could increase the benefits for municipalities. A case study of Stadion Feijenoord was analysed for this research
Expansion Tube Investigation of Shock Stand-Off Distances in High-Enthalpy CO_2 Flow Over Blunt Bodies
The shock standoff distance in front of a blunt body is sensitive to the thermochemical
state of the free stream. Recently, experimental and numerical studies
have reported significantly different bow shock profiles in high-enthalpy carbon
dioxide flows, a discrepancy that may result from non-equilibrium processes during
flow acceleration in ground-based facilities. In this work, an expansion tube is used
to create a Mach 5.7 carbon dioxide flow, matching the stagnation enthalpy and
the velocity of previous studies. Images of shock layers are obtained for spherical
geometries and a scaled model of the Mars Science Lander. Different sphere
diameters are used in order to access non-equilibrium and equilibrium stagnation
line shock profiles predicted by theory. Mars Science Lander profiles at zero angle
of attack are in good agreement with available data from the LENS X expansion
tunnel facility, confirming results are facility-independent for the same type of flow
acceleration, and indicating the flow velocity is a suitable first-order matching parameter
for comparative testing. Heat transfer measurements on the Mars Science
Lander are also presented for the three different angle of attacks, and the results
are consistent with previous studies. Initial results from a proposed organo-metallic
based emission spectroscopy technique for bow shock layer interrogation are also
presented
The Information Geometry of the One-Dimensional Potts Model
In various statistical-mechanical models the introduction of a metric onto
the space of parameters (e.g. the temperature variable, , and the
external field variable, , in the case of spin models) gives an alternative
perspective on the phase structure. For the one-dimensional Ising model the
scalar curvature, , of this metric can be calculated explicitly in
the thermodynamic limit and is found to be . This is positive definite and, for
physical fields and temperatures, diverges only at the zero-temperature,
zero-field ``critical point'' of the model.
In this note we calculate for the one-dimensional -state Potts
model, finding an expression of the form , where is the Potts
analogue of . This is no longer positive
definite, but once again it diverges only at the critical point in the space of
real parameters. We remark, however, that a naive analytic continuation to
complex field reveals a further divergence in the Ising and Potts curvatures at
the Lee-Yang edge.Comment: 9 pages + 4 eps figure
Distribution of Oolitic Sediment Along a Beach-to-Offshore Transect, Pigeon Cay, Cat Island, Bahamas: New Insights Into Modern Ooid Formation
Ooids are a common component of ancient carbonate rocks, but their origin and distribution in Holocene deposits and modem carbonate sands are not fully understood. Even though ooids are well documented from several localities in the Bahamian Archipelago, their occurrence on Cat Island has not been previously studied in detail. In this study we examined the composition and texture of beach sand and six sediment samples collected from the sea floor at approximately 50-meter intervals along an estimated 300 m transect at Pigeon Cay, Cat Island
Evidence of exactness of the mean field theory in the nonextensive regime of long-range spin models
The q-state Potts model with long-range interactions that decay as 1/r^alpha
subjected to an uniform magnetic field on d-dimensional lattices is analized
for different values of q in the nonextensive regime (alpha between 0 and d).
We also consider the two dimensional antiferromagnetic Ising model with the
same type of interactions. The mean field solution and Monte Carlo calculations
for the equations of state for these models are compared. We show that, using a
derived scaling which properly describes the nonextensive thermodynamic
behaviour, both types of calculations show an excellent agreement in all the
cases here considered, except for alpha=d. These results allow us to extend to
nonextensive magnetic models a previous conjecture which states that the mean
field theory is exact for the Ising one.Comment: 10 pages, 4 figure
1D Potts, Yang-Lee Edges and Chaos
It is known that the (exact) renormalization transformations for the
one-dimensional Ising model in field can be cast in the form of a logistic map
f(x) = 4 x (1 - x) with x a function of the Ising couplings. Remarkably, the
line bounding the region of chaotic behaviour in x is precisely that defining
the Yang-Lee edge singularity in the Ising model.
In this paper we show that the one dimensional q-state Potts model for q
greater than or equal to 1 also displays such behaviour. A suitable combination
of Potts couplings can again be used to define an x satisfying f(x) = 4 x (1
-x). The Yang-Lee zeroes no longer lie on the unit circle in the complex z =
exp (h) plane, but their locus is still reproduced by the boundary of the
chaotic region in the logistic map.Comment: 6 pages, no figure
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