@article{LiRybskiKropp2021,
  author    = {Li, Yunfei and Rybski, Diego and Kropp, J{\"u}rgen},
  title     = {Singularity cities},
  series = {Environment and planning. B, Urban analytics and city science},
  volume    = {48},
  journal   = {Environment and planning. B, Urban analytics and city science},
  number    = {1},
  publisher = {Sage Publ.},
  address   = {London},
  issn      = {2399-8083},
  doi       = {10.1177/2399808319843534},
  pages     = {43 -- 59},
  year      = {2021},
  abstract  = {We propose an upgraded gravitational model which provides population counts beyond the binary (urban/non-urban) city simulations. Numerically studying the model output, we find that the radial population density gradients follow power-laws where the exponent is related to the preset gravity exponent gamma. Similarly, the urban fraction decays exponentially, again determined by gamma. The population density gradient can be related to radial fractality and it turns out that the typical exponents imply that cities are basically zero-dimensional. Increasing the gravity exponent leads to extreme compactness and the loss of radial symmetry. We study the shape of the major central cluster by means of another three fractal dimensions and find that overall its fractality is dominated by the size and the influence of gamma is minor. The fundamental allometry, between population and area of the major central cluster, is related to the gravity exponent but restricted to the case of higher densities in large cities. We argue that cities are shaped by power-law proximity. We complement the numerical analysis by economics arguments employing travel costs as well as housing rent determined by supply and demand. Our work contributes to the understanding of gravitational effects, radial gradients, and urban morphology. The model allows to generate and investigate city structures under laboratory conditions.},
  language  = {en}
}
@article{GudipudiLuedekeRybskietal.2018,
  author    = {Gudipudi, Ramana Venkata and L{\"u}deke, Matthias K. B. and Rybski, Diego and Kropp, J{\"u}rgen},
  title     = {Benchmarking urban eco-efficiency and urbanites' perception},
  series = {Cities},
  volume    = {74},
  journal   = {Cities},
  publisher = {Elsevier},
  address   = {Oxford},
  issn      = {0264-2751},
  doi       = {10.1016/j.cities.2017.11.009},
  pages     = {109 -- 118},
  year      = {2018},
  abstract  = {Urbanization as an inexorable global trend stresses the need to identify cities which are eco-efficient. These cities enable socioeconomic development with lower environmental burden, both being multidimensional concepts. Based on this approach, we benchmark 88 European cities using (i) an advanced version of regression residual ranking and (ii) Data Envelopment Analysis (DEA). Our results show that Stockholm, Munich and Oslo perform well irrespective of the benchmarking method. Furthermore, our results indicate that larger European cities are eco-efficient given the socioeconomic benefits they offer compared to smaller cities. In addition, we analyze correlations between a subjective public perception ranking and our objective eco-efficiency rankings for a subset of 45 cities. This exercise revealed three insights: (1) public perception about quality of life in a city is not merely confined to the socioeconomic well-being but rather to its combination with a lower environmental burden; (2) public perception correlates well with both formal ranking outcomes, corroborating the choice of variables; and (3) the advanced regression residual method appears to be more adequate to fit the urbanites' perception ranking (correlation coefficient about 0.6). This can be interpreted as an indication that urbanites' perception reflects the typical eco-efficiency performance and is less influenced by exceptionally performing cities (in the latter case, DEA should have better correlation coefficient). This study highlights that the socioeconomic growth in cities should not be environmentally detrimental as this might lead to significant discontent regarding perceived quality of urban life.},
  language  = {en}
}
@article{RybskiReusserWinzetal.2016,
  author    = {Rybski, Diego and Reusser, Dominik Edwin and Winz, Anna-Lena and Fichtner, Christina and Sterzel, Till and Kropp, J{\"u}rgen},
  title     = {Cities as nuclei of sustainability?},
  series = {Environment and Planning B: Urban Analytics and City Science},
  volume    = {44},
  journal   = {Environment and Planning B: Urban Analytics and City Science},
  number    = {3},
  publisher = {Sage Publ.},
  address   = {London},
  issn      = {2399-8083},
  doi       = {10.1177/0265813516638340},
  pages     = {425 -- 440},
  year      = {2016},
  abstract  = {We have assembled CO2 emission figures from collections of urban GHG emission estimates published in peer-reviewed journals or reports from research institutes and non-governmental organizations. Analyzing the scaling with population size, we find that the exponent is development dependent with a transition from super- to sub-linear scaling. From the climate change mitigation point of view, the results suggest that urbanization is desirable in developed countries. Further, we compare this analysis with a second scaling relation, namely the fundamental allometry between city population and area, and propose that density might be a decisive quantity too. Last, we derive the theoretical country-wide urban emissions by integration and obtain a dependence on the size of the largest city.},
  language  = {en}
}