8,191 research outputs found
Assessing the performance of real estate auctions
This paper investigates the performance of real estate auctions in selling real estate relative to the more traditional method of negotiated sale. Estimates from auctions in Los Angeles during the boom of the mid 1980s show a discount that ranges between 0 and 9 percent, while similar sales in Dallas during the real estate bust of the late 1980s obtained discounts in the 9 to 21 percent range. This evidence is censistent with a theory that predicts larger percentage discounts in down markets. Although these results differ from previous studies of U.S. auctions that find much larger discounts, a comparison of methodologies suggests that previous papers that use a hedonic equation suffer from a selection bias problem, pushing auction coefficients towards finding larger discounts. Another interesting finding is that publishing a reserve price does not affect the estimated auction prices. Finally, the study notes that scattered-site auctions sell at a larger discount than the more homogeneous sales of single-site condominiums and finds no evidence of price declines over the course of an auction. The paper concludes that despite the discounts, auctions are still a viable sales strategy, especially for large sellers that face high holding costs and long average sales times, and for developers of single-site condominium complexes.Real property
The Relativistic Rindler Hydrodynamics
We consider a (d+2)-dimensional class of Lorentzian geometries
holographically dual to a relativistic fluid flow in (d+1) dimensions. The
fluid is defined on a (d+1)-dimensional time-like surface which is embedded in
the (d+2)-dimensional bulk space-time and equipped with a flat intrinsic
metric. We find two types of geometries that are solutions to the vacuum
Einstein equations: the Rindler metric and the Taub plane symmetric vacuum.
These correspond to dual perfect fluids with vanishing and negative energy
densities respectively. While the Rindler geometry is characterized by a causal
horizon, the Taub geometry has a timelike naked singularity, indicating
pathological behavior. We construct the Rindler hydrodynamics up to the second
order in derivatives of the fluid variables and show the positivity of its
entropy current divergence.Comment: 25 pages, 2 appendices; v3: improved presentation, corrected typo
Contract-Based General-Purpose GPU Programming
Using GPUs as general-purpose processors has revolutionized parallel
computing by offering, for a large and growing set of algorithms, massive
data-parallelization on desktop machines. An obstacle to widespread adoption,
however, is the difficulty of programming them and the low-level control of the
hardware required to achieve good performance. This paper suggests a
programming library, SafeGPU, that aims at striking a balance between
programmer productivity and performance, by making GPU data-parallel operations
accessible from within a classical object-oriented programming language. The
solution is integrated with the design-by-contract approach, which increases
confidence in functional program correctness by embedding executable program
specifications into the program text. We show that our library leads to modular
and maintainable code that is accessible to GPGPU non-experts, while providing
performance that is comparable with hand-written CUDA code. Furthermore,
runtime contract checking turns out to be feasible, as the contracts can be
executed on the GPU
Efficiently Generating Geometric Inhomogeneous and Hyperbolic Random Graphs
Hyperbolic random graphs (HRG) and geometric inhomogeneous random graphs (GIRG) are two similar generative network models that were designed to resemble complex real world networks. In particular, they have a power-law degree distribution with controllable exponent beta, and high clustering that can be controlled via the temperature T.
We present the first implementation of an efficient GIRG generator running in expected linear time. Besides varying temperatures, it also supports underlying geometries of higher dimensions. It is capable of generating graphs with ten million edges in under a second on commodity hardware. The algorithm can be adapted to HRGs. Our resulting implementation is the fastest sequential HRG generator, despite the fact that we support non-zero temperatures. Though non-zero temperatures are crucial for many applications, most existing generators are restricted to T = 0. We also support parallelization, although this is not the focus of this paper. Moreover, we note that our generators draw from the correct probability distribution, i.e., they involve no approximation.
Besides the generators themselves, we also provide an efficient algorithm to determine the non-trivial dependency between the average degree of the resulting graph and the input parameters of the GIRG model. This makes it possible to specify the desired expected average degree as input.
Moreover, we investigate the differences between HRGs and GIRGs, shedding new light on the nature of the relation between the two models. Although HRGs represent, in a certain sense, a special case of the GIRG model, we find that a straight-forward inclusion does not hold in practice. However, the difference is negligible for most use cases
Deep Video Color Propagation
Traditional approaches for color propagation in videos rely on some form of
matching between consecutive video frames. Using appearance descriptors, colors
are then propagated both spatially and temporally. These methods, however, are
computationally expensive and do not take advantage of semantic information of
the scene. In this work we propose a deep learning framework for color
propagation that combines a local strategy, to propagate colors frame-by-frame
ensuring temporal stability, and a global strategy, using semantics for color
propagation within a longer range. Our evaluation shows the superiority of our
strategy over existing video and image color propagation methods as well as
neural photo-realistic style transfer approaches.Comment: BMVC 201
Qualitative model-based diagnostics for rocket systems
A diagnostic software package is currently being developed at NASA LeRC that utilizes qualitative model-based reasoning techniques. These techniques can provide diagnostic information about the operational condition of the modeled rocket engine system or subsystem. The diagnostic package combines a qualitative model solver with a constraint suspension algorithm. The constraint suspension algorithm directs the solver's operation to provide valuable fault isolation information about the modeled system. A qualitative model of the Space Shuttle Main Engine's oxidizer supply components was generated. A diagnostic application based on this qualitative model was constructed to process four test cases: three numerical simulations and one actual test firing. The diagnostic tool's fault isolation output compared favorably with the input fault condition
New Developments in Water Rights on Public Lands: Federal Rights and State Interests
25 pages.
Contains footnotes and 2 pages of references
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