A system for calculating the merchantable volume of oak trees in the northwest of the state of Chihuahua, Mexico

The taper functions of Kozak （1988）, Bi （2000） and Fang et al. （2000） were comparatively analyzed in the present paper to develop a system for calculating the merchantable volume of oaks in the northwestern region of the state of Chihuahua （Mexico）. Taper data corresponding to 298 trees were collected in mixed and uneven-aged pine-oak stands located throughout the study area, and covering the cxisting range of ages, stand densities and sites. Results show that the compatible segmented model developed by Fang et al. （2000） best described the experimental data and is therefore recommended for estimating tree diameter at a specific height, height to a specific diameter, merchantable volume, and total volume for oaks. The equation developed in this study is a fundamental tool for use in forest surveys in the study region and is simple enough to ensure its operational implementation. The results of the statistical analysis show that the equation can be recommended for other regions, although some local adaptations may be needed.

Changes in Relative Plate Motion during the Isan Orogeny(1670-1500Ma) and Implications for Pre-Rodinia Reconstructions

Foliation inflexion/intersection axes （FIAs） preserved within porphyroblasts that grew throughout Isan orogenesis reveal significant anticlockwise changes in the direction of bulk horizontal shortening between 1670 and 1500 Ma from NE-SW, N-S, E-W to NW-SE. This implies an anticlockwise shift in relative plate motion with time during the Isan orogeny. Dating monazite grains amongst the axial planar foliations defining three of the four FIAs enabled an age for the periods of relative plate motion that produced these structures to be determined. Averaging the ages from monazite grains defining each FIA set revealed 1649^-12 Ma for NE-SW shortening, 1645±7 Ma for N-S shortening, and 1591±10 Ma for that directed E-W. Inclusion trail asymmetries indicate shear senses of top to the SW for NW-SE FIAs and dominantly top to the N for E-W FIAs, reflecting thrusting towards the SW and N. No evidence for tectonism related to early NE-SW bulk horizontal shortening has previously been detected in the Mount Isa Inlier. Amalgamation of the Broken Hill and possibly the Gawler provinces with the Mount Isa province may have taken place during these periods of NE-SW and N-S-directed thrusting as the ages of tectonism are similar. Overlapping dates, tectonic, metamorphic, and metallogenic similarities between eastern Australia （Mount Isa and Broken Hill terranes） and the southwest part of Laurentia imply a most probable connection between both continental masses. Putting Australia in such position with respect to North America during the Late-Paleo-to-Mesoproterozoic time is consistent with the AUSWUS model of the Rodinia supercontinent.

AN ALGORITHM FOR DETERMINING CONCAVE VERTEX OF OBJECT BASED ON VECTOR PRODUCT

Concave vertex of an object is an important parameter for analyzing an object’s shape. A new algorithm for searching concave vertex is proposed in this paper. The new algorithm requires tracking the border firstly,and then uses sampling border to obtain coordinates sequence of discrete boundary points. Each sampling point of the discrete border is determined to be either concave or convex according to the value of vector product. Two inflexions can be searched by the change of concavo-convex trend. The region between two inflexions is defined as concave area. The values of distance are calculated between all boundary points on the concave area and a straight line connected by two inflexions. The boundary point corresponding to the greatest distances is max concave vertex,or the object’s concave vertex. Experimental results have proved that the new algorithm can extract the max concave vertexes of an object accurately and reliably.

Modelling the spreading rate of controlled communicable epidemics through an entropy-based thermodynamic model

A model based on a thermodynamic approach is proposed for predicting the dynamics of communicable epidemics assumed to be governed by controlling eforts of multiple scales so that an entropy is associated with the system.All the epidemic details are factored into a single and time-dependent coefcient,the functional form of this coefcient is found through four constraints,including notably the existence of an inflexion point and a maximum.The model is solved to give a log-normal distribution for the spread rate,for which a Shannon entropy can be defined.The only parameter,that characterizes the width of the distribution function,is uniquely determined through maximizing the rate of entropy production.This entropy-based thermodynamic(EBT)model predicts the number of hospitalized cases with a reasonable accuracy for SARS in the year 2003.This EBT model can be of use for potential epidemics such as avian influenza and H7N9 in China.