Forecasting and Analyzing World Commodity Prices

The authors develop simple econometric models to analyze and forecast two components of the Bank of Canada commodity price index: the Bank of Canada non-energy (BCNE) commodity prices and the West Texas Intermediate crude oil price. They present different methodologies to identify transitory and permanent components of movements in these prices. A structural vector autoregressive model is used for real BCNE prices and a multiple structural-break technique is employed for real crude oil prices. The authors use these transitory and permanent components to develop forecasting models. They assess various aspects of the models' performance. Their main results indicate that: (i) the world economic activity and real U.S.-dollar effective exchange rate explain much of the cyclical variation of real BCNE prices, (ii) real crude oil prices have two structural breaks over the sample period, and recently their link with the world economic activity has been quite strong, and (iii) the models outperform benchmark models, namely a vector autoregressive model, an autoregressive model, and a random-walk model, in terms of out-of-sample forecasting.Econometric and statistical methods

A Structural Small Open-Economy Model for Canada

The authors develop a small open-economy dynamic stochastic general-equilibrium (DSGE) model in an attempt to understand the dynamic relationships in Canadian macroeconomic data. The model differs from most recent DSGE models in two key ways. First, for prices and wages, the authors use the time-dependent staggered contracting model of Dotsey, King, and Wolman (1999) and Wolman (1999), rather than the Calvo (1983) specification. Second, to model investment, the authors adopt Edge's (2000a, b) framework of time-to-build with ex-post inflexibilities. The model's parameters are chosen to minimize the distance between the structural model's impulse responses to interest rate, demand (consumption), and exchange rate shocks and those from an estimated vector autoregression (VAR). The majority of the model's theoretical impulse responses fall within the 5 and 95 per cent confidence intervals generated by the VAR.Business fluctuations and cycles; Economic models; Inflation and prices

The Reverse Hölder Inequality for the Solution to p-Harmonic Type System

Some inequalities to A-harmonic equation A(x,du)=d∗v have been proved. The A-harmonic equation is a particular form of p-harmonic type system A(x,a+du)=b+d∗v only when a=0 and b=0. In this paper, we will prove the Poincaré inequality and the reverse Hölder inequality for the solution to the p-harmonic type system

Comparative Analysis on Elastic-plastic Analytical Methods for Tunnel Surrounding Rocks

Elastic-plastic analysis is an important way to obtain the mechanical characteristics of surrounding rocks. However, selecting a reasonable analytical method is difficult. To explore the differences between the surrounding rocks constitutive relation and yield criterion analytical methods, the stress distribution and deformation characteristics of tunnel surrounding rocks at the −817 m firefighting material chamber of the Wangfenggang Well, Xieyi Mine, Huainan Coal Industry Group (China) were analyzed by using the bilinear constitutive relation and unified strength criterion analytical methods. Calculated results of the two analytical methods were compared. The radius and displacement evolution laws of the plastic region on tunnel surrounding rocks with in situ rock stress and supporting resistance were discussed. Results demonstrate that compared with the unified strength criterion analytical method, the bilinear constitutive relation analytical method avoids the influences of intermediate principal stress coefficient on results and the tangential stress distribution curve is smooth. The calculated radius of the plastic region and periphery displacement of the tunnel are 4,365 m and 87,373 mm, which are higher than those of the unified strength criterion analytical method. Stress difference is a major factor that influences the mechanical characteristics of tunnel surrounding rocks. As the stress difference decreases from 20,4 MPa to 16,4 MPa, the radius of the plastic region and periphery displacement of the tunnel decrease by 0,697 m and 26,73 mm, respectively. This study provides theoretical references for the practical selection of elastic-plastic analytical method for tunnel surrounding rocks

Supervised descent method (SDM) applied to accurate pupil detection in off-the-shelf eye tracking systems

The precise detection of pupil/iris center is key to estimate gaze accurately. This fact becomes specially challenging in low cost frameworks in which the algorithms employed for high performance systems fail. In the last years an outstanding effort has been made in order to apply training-based methods to low resolution images. In this paper, Supervised Descent Method (SDM) is applied to GI4E database. The 2D landmarks employed for training are the corners of the eyes and the pupil centers. In order to validate the algorithm proposed, a cross validation procedure is performed. The strategy employed for the training allows us to affirm that our method can potentially outperform the state of the art algorithms applied to the same dataset in terms of 2D accuracy. The promising results encourage to carry on in the study of training-based methods for eye tracking.Spanish Ministry of Economy,Industry and Competitiveness, contracts TIN2014-52897-R and TIN2017-84388-