The effect of drying and storage conditions on case hardening of scots pine and norway spruce timber

Case hardening is a feature of dried wood that causes the wood to deform (cup) after re-sawing and equalising the moisture content. VTT has analysed case hardening with the aid of the simulation model PEO and with experimental drying, conditioning and storage tests. Case hardening cannot be predicted by the moisture content gradient alone. However, the case hardening gap after drying to a high final moisture content of 18% is nearly identical to the calculated gap caused by cupping when the moisture gradients of the two halves of the test piece are equalised.24 hours (proposed in ENV 14464) is too little time to show the total cupping when keeping the sliced specimens in a plastic bag. Thus the test according the standard doesn’t show the whole cupping tendency of, for example, panels when the moisture content is equalised after re-sawing the timber and planing the billets.Increasing the kiln drying rate increases the resulting case hardening tendency. With effective conditioning at the drying temperature, or with steaming after cooling, it is possible to reduce or remove the case hardening. But at normal temperatures in end-use or storage of timber the case hardening diminishes very slowly, despite the equalising of the moisture content in the cross-section

Discovery of error-tolerant biclusters from noisy gene expression data

An important analysis performed on microarray gene-expression data is to discover biclusters, which denote groups of genes that are coherently expressed for a subset of conditions. Various biclustering algorithms have been proposed to find different types of biclusters from these real-valued gene-expression data sets. However, these algorithms suffer from several limitations such as inability to explicitly handle errors/noise in the data; difficulty in discovering small bicliusters due to their top-down approach; inability of some of the approaches to find overlapping biclusters, which is crucial as many genes participate in multiple biological processes. Association pattern mining also produce biclusters as their result and can naturally address some of these limitations. However, traditional association mining only finds exact biclusters, whic

Possible causes of data model discrepancy in the temperature history of the last Millennium

Model simulations and proxy-based reconstructions are the main tools for quantifying pre-instrumental climate variations. For some metrics such as Northern Hemisphere mean temperatures, there is remarkable agreement between models and reconstructions. For other diagnostics, such as the regional response to volcanic eruptions, or hemispheric temperature differences, substantial disagreements between data and models have been reported. Here, we assess the potential sources of these discrepancies by comparing 1000-year hemispheric temperature reconstructions based on real-world paleoclimate proxies with climate-model-based pseudoproxies. These pseudoproxy experiments (PPE) indicate that noise inherent in proxy records and the unequal spatial distribution of proxy data are the key factors in explaining the data-model differences. For example, lower inter-hemispheric correlations in reconstructions can be fully accounted for by these factors in the PPE. Noise and data sampling also partly explain the reduced amplitude of the response to external forcing in reconstructions compared to models. For other metrics, such as inter-hemispheric differences, some, although reduced, discrepancy remains. Our results suggest that improving proxy data quality and spatial coverage is the key factor to increase the quality of future climate reconstructions, while the total number of proxy records and reconstruction methodology play a smaller role

The effect of drying and storage conditions on case hardening of scots pine and norway spruce timber

Case hardening is a feature of dried wood that causes the wood to deform (cup) after re-sawing and equalising the moisture content. VTT has analysed case hardening with the aid of the simulation model PEO and with experimental drying, conditioning and storage tests. Case hardening cannot be predicted by the moisture content gradient alone. However, the case hardening gap after drying to a high final moisture content of 18% is nearly identical to the calculated gap caused by cupping when the moisture gradients of the two halves of the test piece are equalised.24 hours (proposed in ENV 14464) is too little time to show the total cupping when keeping the sliced specimens in a plastic bag. Thus the test according the standard doesn’t show the whole cupping tendency of, for example, panels when the moisture content is equalised after re-sawing the timber and planing the billets.Increasing the kiln drying rate increases the resulting case hardening tendency. With effective conditioning at the drying temperature, or with steaming after cooling, it is possible to reduce or remove the case hardening. But at normal temperatures in end-use or storage of timber the case hardening diminishes very slowly, despite the equalising of the moisture content in the cross-section