LPMLEn - A frequency domain method to estimate vertical streambed fluxes and sediment thermal properties in semi-infinite and bounded domains

This paper presents the LPMLEn, a new method to estimate vertical flux and thermal diffusivity from streambed temperature time-series using the frequency domain. The main advantages of this new method are: (1) the use of multiple frequencies and multiple sensors for the parameter estimation; (2) noise/uncertainty handling in an optimal way; (3) the possibility to estimate the parameters with both semi-infinite and bounded domain models; and (4) the compensation for temperature drifts in the data known as transients. The capabilities of the LPMLEn are demonstrated using both synthetic and field data, highlighting the advantages of the bounded domain model over the semi-infinite domain model in the parameter estimation process. (LPMLEn - A code for estimating heat transport parameters in 1D, HydroShare (43.0 MB), http://www.hydroshare.org/resource/3b13760174174c31988120baeb84e2e8<br/

LPMLEn - A frequency domain method to estimate vertical streambed fluxes and sediment thermal properties in semi-infinite and bounded domains

This paper presents the LPMLEn, a new method to estimate vertical flux and thermal diffusivity from streambed temperature time-series using the frequency domain. The main advantages of this new method are: (1) the use of multiple frequencies and multiple sensors for the parameter estimation; (2) noise/uncertainty handling in an optimal way; (3) the possibility to estimate the parameters with both semi-infinite and bounded domain models; and (4) the compensation for temperature drifts in the data known as transients. The capabilities of the LPMLEn are demonstrated using both synthetic and field data, highlighting the advantages of the bounded domain model over the semi-infinite domain model in the parameter estimation process. (LPMLEn - A code for estimating heat transport parameters in 1D, HydroShare (43.0 MB), http://www.hydroshare.org/resource/3b13760174174c31988120baeb84e2e

Improving the theoretical underpinnings of process-based hydrologic models

In this Commentary we argue that it is possible to improve the physical realism of hydrologic models by making better use of existing hydrologic theory. We address the following questions: (1) what are some key elements of current hydrologic theory; (2) how can those elements best be incorporated where they may be missing in current models; and (3) how can we evaluate competing hydrologic theories across scales and locations? We propose that hydrologic science would benefit from a model-based community synthesis effort to reframe, integrate and evaluate different explanations of hydrologic behavior, and provide a controlled avenue to find where understanding falls short. This article is protected by copyright. All rights reserved

Stevens’ Direct Scaling Methods and the Uniqueness Problem

Direct scaling methods, ratio estimation, ratio production, uniqueness problem, scale types, axiomatic measurement theory,

Equilibria of Graphical Games with Symmetries

We study graphical games where the payoff function of each player satisfies one of four types of symmetries in the actions of his neighbors. We establish that deciding the existence of a pure Nash equilibrium is NP-hard in graphical games with each of the four types of symmetry. Using a characterization of games with pure equilibria in terms of even cycles in the neighborhood graph, as well as a connection to a generalized satisfiability problem, we identify tractable subclasses of the games satisfying the most restrictive type of symmetry. In the process, we characterize a satisfiability problem that remains NP-hard in the presence of a matching, a result that may be of independent interest. Finally, games with symmetries of two of the four types are shown to possess a symmetric mixed equilibrium which can be computed in polynomial time. We have thus identified a class of games where the pure equilibrium problem is computationally harder than the mixed equilibrium problem, unless P=NP