Owners of developed land versus owners of undeveloped land: why land use is more constrained in the Bay Area than in Pittsburgh

We model residential land use constraints as the outcome of a political economy game between owners of developed and owners of undeveloped land. Land use constraints are interpreted as shadow taxes that increase the land rent of already developed plots and reduce the amount of new housing developments. In general equilibrium, locations with nicer amenities are more developed and, as a consequence, more regulated. We test our model predictions by geographically matching amenity, land use, and historical Census data to metropolitan area level survey data on regulatory restrictiveness. Following the predictions of the model, we use amenities as instrumental variables and demonstrate that metropolitan areas with better amenities are more developed and more tightly regulated than other areas. Consistent with theory, metropolitan areas that are more regulated also grow more slowly

On the Origins of Land Use Regulations: Theory and Evidence from US Metro Areas

We model residential land use constraints as the outcome of a political economy game between owners of developed and owners of undeveloped land. Land use constraints benefit the former group (via increasing property prices) but hurt the latter (via increasing development costs). More desirable locations are more developed and, as a consequence of political economy forces, more regulated. Using an IV approach that directly follows from our model we find strong and robust support for our predictions. The data provide weak or no support for alternative hypotheses whereby regulations reflect the wishes of the majority of households or efficiency motives.Land use regulations, zoning, land ownership, housing supply

The actual impedance of non-reflecting boundary conditions : implications for the computation of resonators

Non-reflecting boundary conditions are essential elements in the computation of many compressible flows: such simulations are very sensitive to the treatment of acoustic waves at boundaries. Non-reflecting conditions allow acoustic waves to propagate through boundaries with zero or small levels of reflection into the domain. However, perfectly non-reflecting conditions must be avoided because they can lead to ill-posed problems for the mean flow. Various methods have been proposed to construct boundary conditions which can be sufficiently non-reflecting for the acoustic field while still making the mean-flow problem well posed. This paper analyses a widely-used technique for non-reflecting outlets (Rudy and Strikwerda, Poinsot and Lele). It shows that the correction introduced by these authors can lead to large reflection levels and non-physical resonant behaviors. A simple scaling is proposed to evaluate the relaxation coefficient used in theses methods for a non-reflecting outlet. The proposed scaling is tested for simple cases (ducts) both theoretically and numerically

Accounting for convective effects in zero-Mach-number thermoacoustic models

This paper presents a methodology to account for some mean-flow effects on thermo-acoustic instabilities when using the zero-Mach-number assumption. It is shown that when a computational domain is represented under the M=0 assumption, a nonzero-Mach-number element can simply be taken into account by imposing a proper acoustic impedance at the boundaries so as to mimic the mean flow effects in the outer, not computed flow domain. A model that accounts for the coupling between acoustic and entropy waves is presented. It relies on a “delayed entropy coupled boundary condition” (DECBC) for the Helmholtz equation satisfied by the acoustic pressure. The model proves able to capture low-frequency entropic modes even without mean-flow terms in the fluctuating pressure equation

Fractal-like structures in colloid science

The present work aims at reviewing our current understanding of fractal structures in the frame of colloid aggregation as well as the possibility they offer to produce novel structured materials. In particular, the existing techniques to measure and compute the fractal dimension df are critically discussed based on the cases of organic/inorganic particles and proteins. Then the aggregation conditions affecting df are thoroughly analyzed, pointing out the most recent literature findings and the limitations of our current understanding. Finally, the importance of the fractal dimension in applications is discussed along with possible directions for the production of new structured materials

New economic geography: Multiple equilibria, welfare and political economy.

This thesis contributes to the body of research known as the new economic geography. According to this paradigm, increasing returns to scale at the firm level, monopolistic competition, and transportation costs interact in shaping the spatial distribution of economic activity. The introductory chapter lays out the motivation of this thesis and puts it into the perspective of the existing literature. Chapter 1 introduces a typical model of new economic geography: the nature of the agglomeration and dispersion forces it displays is recurrent in this body of research; the model also displays multiple equilibria. The welfare properties of these equilibria are also analysed. Chapter 2 completely characterizes the set of equilibria of a wide range of models that are the quintessence of the new economic geography paradigm. The model of chapter 2 is shown to share the qualitative features of these models. Chapter 3 integrates a simple version of the model chapter 2 within a political economy framework. The welfare analysis of chapter 2 provides the motivation for this theoretical exercise. Chapter 4 seeks to provide an answer to the important but thus far neglected question of what is the mechanism that actually determines the magnitude policies that seek to affect the equilibrium spatial allocation of industries. The geography model is integrated in a fully specified political economy process of policy selection. Chapter 4 extends the model of chapter 2 to deal with the issue of the 'fragmentation' of the production process when new economic geography forces are at play. Finally, the analysis of chapter 5 contributes to the growing literature on the labour market imperfections as a driving force for agglomeration. In particular it shows how the hold-up problem can be softened or worsened by the cluster of industries using workers with similar skills

A Thickened-Hole Model for Large Eddy Simulations over Multiperforated Liners

International audienceIn aero-engines, mutiperforation cooling systems are often used to shield the combustor wall and ensure durability of the engine. Fresh air coming from the casing goes through thousands of angled perforations and forms a film which protects the liner. When performing Large Eddy Simulations (LES) of a real engine, the number of sub-millimetric holes is far too large to allow a complete and accurate description of each aperture. Homogeneous models allow to simulate multiperforated plates with a mesh size bigger than the hole but fail in representing the jet penetration and mixing. A heterogeneous approach is proposed in this study, where the apertures are thickened if necessary so that the jet-crossflow interaction is properly represented. Simulations using homogeneous and thickened-hole models are compared to a fully resolved computation for various grid resolutions in order to illustrate the potential of the method

Temperature and pollution control in flames

We apply control theory for PDEs to flame control. The targeted flame is calculated with complex chemistry. For pollutant control in flames we study both the control of temperature distribution in the flame and flame length at given fuel rate in the flow. Approximate state and sensitivity evaluations as well as mesh adaptation are used to keep the complexity as low as possible and get mesh independent results. In addition, a new recursive semi-deterministic global optimization approach is tested

Stability analysis of thermo-acoustic nonlinear eigenproblems in annular combustors. Part II. Uncertainty quantification

Monte Carlo and Active Subspace Identification methods are combined with first- and second-order adjoint sensitivities to perform (forward) uncertainty quantification analysis of the thermo-acoustic stability of two annular combustor configurations. This method is applied to evaluate the risk factor, i.e., the probability for the system to be unstable. It is shown that the adjoint approach reduces the number of nonlinear-eigenproblem calculations by up to $\sim\mathcal{O}(M)$, as many as the Monte Carlo samples.European Research Council (Project ALORS 2590620), Royal Academy of Engineering (Research Fellowships Scheme

Constructing Physically Consistent Subgrid-Scale Models for Large-Eddy Simulation of Incompressible Turbulent Flows

We studied the construction of subgrid-scale models for large-eddy simulationof incompressible turbulent flows, focusing on consistency with importantmathematical and physical properties. In particular, we considered the symmetriesof the Navier-Stokes equations, and the near-wall scaling and dissipation behaviorof the turbulent stresses. After showing that existing models do not all satisfy thedesired properties, we discussed a general class of subgrid-scale models based onthe local filtered velocity gradient. We provided examples of models from this classthat preserve several of the symmetries of the Navier-Stokes equations and exhibitthe same near-wall scaling behavior as the turbulent stresses. Furthermore, thesemodels are capable of describing nondissipative effects