Strain and Shrinkage Force in Wood Under Kiln Drying Conditions. I. Measuring Strain and Shrinkage Under Controlled Climate Conditions. Equipment and Preliminary Results

Holzforschung ◽  
1995 ◽  
Vol 49 (4) ◽  
pp. 363-368 ◽  
Author(s):  
Staffan Svensson
Keyword(s):  
Climate Conditions ◽  
Kiln Drying ◽  
Preliminary Results ◽  
Shrinkage Force ◽  
Drying Conditions

scholarly journals Pedogenic and subaerial exposure microfabrics in a late Carboniferous-early Permian carbonate-volcanic lacustrine-palustrine system (San Ignacio Formation, Frontal Cordillera, Argentina)

2020 ◽  
Vol 47 (2) ◽  
pp. 275
Author(s):  
Isabel Méndez-Bedia ◽  
Gloria Gallastegui ◽  
Pedro Busquets ◽  
Silvia N. Césari ◽  
Carlos O. Limarino ◽  
...  
Keyword(s):  
Wide Spectrum ◽  
Volcanic Rocks ◽  
Climatic Conditions ◽  
Late Carboniferous ◽  
Early Permian ◽  
Humid Climate ◽  
Climate Conditions ◽  
Subaerial Exposure ◽  
Drying Conditions ◽  
Micro Organisms

In the Argentinian Andes (Frontal Cordillera) the upper part of the late Carboniferous-early Permian San Ignacio Formation is made up of lacustrine-palustrine microbial carbonates and interbedded volcanic deposits. In this lacustrine-palustrine environment a natural monospecific forest was developed. The deposits of this sedimentary-volcanic succession were repeatedly subjected to subaerial exposure and modified by pedogenesis to varying degrees giving rise to paleosoils development. Diagenetic microfabrics were well preserved in the carbonates and volcanic rocks. The carbonate microfabrics comprise a wide spectrum of features consisting of root marks and stumps-related structures (rhizoliths, alveolar texture, tunnel-like structures and coprolites of arthropods), pisoids, coated grains and pseudomicrokarst, cracking, brecciated and nodular fabrics, and grainification also occur corresponding to different stages in the pedogenic evolution. Meteoric dissolution and cementation processes are observed; examples are well identified by scanning electron microscope showing silica-filled voids in partially dissolved carbonates and growths of inorganic carbonate microcrystals or of microbial origin in voids. Other different types of cements can be seen such as discontinuous carbonate crusts, ribbon spar, cavities with silt infillings and pendant cements. The whole set of these microfabrics are indicative of wetting, desiccation and meteoric conditions (vadose and phreatic). The abundance of plant roots and associated micro-organisms mainly of bacterial origin (micro-rods, short rod-shapes, nano-fibres, filaments and nano-spheres) played an important role in the pedogenic and subaerial diagenetic processes affecting these deposits. The immature character of the paleosoils and absence of calcretes point out to short intervals of subaerial exposure due to oscillating fluctuations in water level, intermittent volcanic supply, tectonic subsidence and oscillating climatic conditions. The whole of the macro and microfabrics reveals that the prevailing weather could correspond to an intermediate between semi-arid to sub-humid, however the alternating wetting and drying conditions in which the fossil forest developed and the abundance and diversity of micro-organisms, suggest a transition to sub-humid climate conditions.

scholarly journals Drying quality and colour of subfossil oak from central Serbia

2018 ◽  
pp. 157-172
Author(s):  
Marko Veizovic ◽  
Zdravko Popovic ◽  
Nebojsa Todorovic ◽  
Goran Milic
Keyword(s):  
Colour Change ◽  
Case Hardening ◽  
Drying Process ◽  
Oak Wood ◽  
Kiln Drying ◽  
Conventional Drying ◽  
Drying Conditions ◽  
Subfossil Wood ◽  
Drying Quality

The subject of this paper is the analysis of the quality of natural and conventional drying of subfossil oak wood. In addition to the drying quality, the colour of this material, as well as the effect of the drying process on colour change have been tested. The subfossil oak logs that were used in this experiment originate from the Morava River in Central Serbia. After sawing, timber was air-dried to about 20% moisture content (MC) followed by kiln-drying to 9.5% MC. By examining the quality of air-drying of the subfossil oak wood, a high presence of cracks was found, as well as the inaccuracy of humidity measurement using electric moisture meters. The stack for kiln-drying consisted of 24 boards, of which 4 were used for the monitoring of MC and MC distribution across the thickness of plank during drying. Drying quality was evaluated after the kiln-drying process. Although mild drying conditions during kiln-drying were applied, the gap as a measure of case-hardening had a value greater than usual for oak of same thickness. It was found that the drying process has no significant effect on the change in the colour of subfossil wood. The colour of the subfossil oak wood was significantly darker than the usual oak wood, and the colour difference between the central and the outer parts of the trunk of the subfossil oak was determined.

scholarly journals Hemispheric-scale comparison and evaluation of passive-microwave snow algorithms

2002 ◽  
Vol 34 ◽  
pp. 38-44 ◽  
Author(s):  
Richard L. Armstrong ◽  
Mary J. Brodzik
Keyword(s):  
Satellite Data ◽  
Large Scale ◽  
Snow Water Equivalent ◽  
Full Range ◽  
Passive Microwave ◽  
General Tendency ◽  
Climate Conditions ◽  
Preliminary Results ◽  
Snow Water ◽  
Microwave Data

AbstractPassive-microwave satellite remote sensing can greatly enhance large-scale snow measurements based on visible satellite data alone because of the ability to acquire data through most clouds or during darkness as well as to provide a measure of snow depth or water equivalent. This study provides preliminary results from the comparison and evaluation of several different passive-microwave algorithms. These algorithms represent examples which include both mid- and high-frequency channels, vertical and horizontal polarizations and polarization-difference approaches. In our comparisons we utilize larger, more comprehensive, validation datasets which can be expected to provide a full range of snow/climate conditions rather than limited data which may only represent a snapshot in time and space. Evaluation of snow extent derived from passive-microwave data is undertaken through comparison with the U.S. National Oceanic and Atmospheric Administration (NOAA) Northern Hemisphere snow charts which are based on visible-band satellite data. Results clearly indicate those time periods and geographic regions where the two techniques agree and where they tend to consistently disagree. Validation of snow water equivalent derived from passive-microwave data is undertaken using measurements from snow-course transects in the former Soviet Union. Preliminary results indicate a general tendency for nearly all of the algorithms to underestimate snow water equivalent.

scholarly journals Impact of Kiln Drying Schedule upon Some Mechanical Properties of Poplar Wood

2012 ◽  
Vol 4 (3) ◽  
pp. 158-162
Author(s):  
Hadi DASHTI ◽  
Mahdi SHAHVERDI ◽  
Seyed Ali HAJI MIRZA TAYEB ◽  
Hossein LOTFIZADEH
Keyword(s):  
Mechanical Properties ◽  
Statistical Analysis ◽  
Mechanical Strength ◽  
Compression Strength ◽  
Poplar Wood ◽  
Grain Hardness ◽  
Wood Drying ◽  
Kiln Drying ◽  
Schedule Compression ◽  
Drying Conditions

In the present research, the effect of three kiln drying schedules of T5-D2, T5-D4, and T5-D6 on poplar wood mechanical properties was investigated. The lumber was dried in a convectional laboratory kiln and then the compression strength in a parallel and perpendicular direction toward the grain, hardness, and nail withdrawal resistance were evaluated. The obtained results indicated with change from schedule T5-D2 to T5-D4, compression strength whether parallel or perpendicular to grain, hardness in tangential, radial, and transverse surfaces as well as, nail withdrawal resistance in tangential, radial, and transverse surfaces increased up to 18.1, 7.1, 16.4, 19.7, 14.1, 19.8, 5.7, and 9.2 % respectively, as against schedule T5-D2. Despite T5-D4 schedule, compression strength parallel to grain dropped in specimens dried by schedule T5-D6. However, nail withdrawal resistance of specimens dried by T5-D6 schedule was higher in all the three surfaces than the two other schedules. As regards, the T5-D6 schedule, compression strength perpendicular to grain and also hardness in all the three surfaces rose as opposed to that of T5-D2 schedule, but showed a decrease in comparison to the corresponding figure in T5-D4. Moreover, statistical analysis revealed that except the compression strength perpendicular to grain, other mechanical strength inducing by various wood drying conditions were put in separate statistical groups.

scholarly journals Quantifying the demographic vulnerabilities of dry woodlands to climate and competition using range-wide monitoring data

2020 ◽  
Author(s):  
Robert K. Shriver ◽  
Charles B. Yackulic ◽  
David M. Bell ◽  
John B. Bradford
Keyword(s):  
Tree Species ◽  
Large Scale ◽  
Pinus Edulis ◽  
Monitoring Data ◽  
Ecosystem Structure ◽  
Remotely Sensed Data ◽  
Climate Conditions ◽  
Drying Conditions ◽  
And Function ◽  
Ecosystem Structure And Function

AbstractClimate change is expected to alter the distribution and abundance of tree species, impacting ecosystem structure and function. Yet, anticipating where this will occur is often hampered by a lack of understanding of how demographic rates, most notably recruitment, vary in response to climate and competition across a species range. Using large-scale monitoring data on two dry woodland tree species (Pinus edulis and Juniperus osteosperma), we develop an approach to infer recruitment, survival, and growth of both species across their range. In doing so, we account for ecological and statistical dependencies inherent in large-scale monitoring data. We find that warming and drying conditions generally lead to declines in recruitment and survival, but there were some idiosyncrasy in the strength of responses across species. Climate conditions lead to vulnerable regions, such as Pinus edulis in N. Arizona, where both survival and recruitment are low. Our approach provides a path forward for leveraging emerging large-scale monitoring and remotely sensed data to anticipate the impacts of global change on species distributions.

The O–C diagrams of minor planets − a new approach to modelling the rotation

1999 ◽  
Vol 173 ◽  
pp. 185-188
Author(s):  
Gy. Szabó ◽  
K. Sárneczky ◽  
L.L. Kiss
Keyword(s):  
Error Analysis ◽  
Time Dependence ◽  
Theoretical Work ◽  
Minor Planet ◽  
Minor Planets ◽  
New Approach ◽  
Preliminary Results ◽  
Ccd Observations

AbstractA widely used tool in studying quasi-monoperiodic processes is the O–C diagram. This paper deals with the application of this diagram in minor planet studies. The main difference between our approach and the classical O–C diagram is that we transform the epoch (=time) dependence into the geocentric longitude domain. We outline a rotation modelling using this modified O–C and illustrate the abilities with detailed error analysis. The primary assumption, that the monotonity and the shape of this diagram is (almost) independent of the geometry of the asteroids is discussed and tested. The monotonity enables an unambiguous distinction between the prograde and retrograde rotation, thus the four-fold (or in some cases the two-fold) ambiguities can be avoided. This turned out to be the main advantage of the O–C examination. As an extension to the theoretical work, we present some preliminary results on 1727 Mette based on new CCD observations.

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