Biomass and Gasification Properties of Young Populus Clones

Studies were conducted to establish baseline information for use in characterizing poplar clones (Populus spp.) as an energy or fiber feedstock. Size and survival of 4-year-old trees varied significantly among the 29 clones evaluated, but larger trees generally had the best survival and are highly important in clonal comparisons. The high average mortality indicated that coppicing as a management strategy to grow these clones for fiber is questionable, at least with the clones being tested. Characteristics of the wood were similar to those of soft hardwoods; the mean value of gross heat of combustion was 18.9 kJ/g (4,520 cal/g); the fiber length was relatively short (0.84 mm); the ash content was 0.39%; and the specific gravity was 0.37. Mean specific gravity values for the bark and wood were 0.37 at the tree base and 0.34 at dbh (all based on green volume).In general, wood was lower in gross heat of combustion and higher in ash content than bark, but specific gravity did not differ significantly. The whole-tree bark/wood heat of combustion was between the values for the two components. Chemical properties between selected clones were not different.Steam gasification of four poplar clones (selected from the better clones) conducted in a fluidizedbed, bench-scale reactor over a temperature range of 595 to 617° showed no significant differences among them. The response variables considered were dry gas composition, gas higher heating value, dry gas volumetric and mass yields, carbon conversion to gas, and energy recovery

Biomass and Wood Properties of Young Silver Maple Clones

Biomass properties were determined to characterize the differences between young silver maple clones as an energy source or fiber source feedstock. Size varied significantly among 25 maple sources evaluated, but larger trees generally had the better survival, which is highly important in clonal comparisons. Characteristics of the wood were similar to those of soft hardwoods; the mean value of gross heat of combustion was 19.6 kJ/g; the fiber length was relatively short (0.74 mm); the ash content was 0.291; and the specific gravity was 0.43. Clonal differences were significant

Bayesian inference for finite mixtures of generalized linear models with random effects

We present an hierarchical Bayes approach to modeling parameter heterogeneity in generalized linear models. The model assumes that there are relevant subpopulations and that within each subpopulation the individual-level regression coefficients have a multivariate normal distribution. However, class membership is not known a priori, so the heterogeneity in the regression coefficients becomes a finite mixture of normal distributions. This approach combines the flexibility of semiparametric, latent class models that assume common parameters for each sub-population and the parsimony of random effects models that assume normal distributions for the regression parameters. The number of subpopulations is selected to maximize the posterior probability of the model being true. Simulations are presented which document the performance of the methodology for synthetic data with known heterogeneity and number of sub-populations. An application is presented concerning preferences for various aspects of personal computers.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/45757/1/11336_2005_Article_BF02294188.pd

Collins and Sivers asymmetries in muonproduction of pions and kaons off transversely polarised protons

Measurements of the Collins and Sivers asymmetries for charged pions and charged and neutral kaons produced in semi-inclusive deep-inelastic scattering of high energy muons off transversely polarised protons are presented. The results were obtained using all the available COMPASS proton data, which were taken in the years 2007 and 2010. The Collins asymmetries exhibit in the valence region a non-zero signal for pions and there are hints of non-zero signal also for kaons. The Sivers asymmetries are found to be positive for positive pions and kaons and compatible with zero otherwise. © 2015