Computer Aided Identification of the Moisture Transport Parameters in Spruce Wood

Holzforschung ◽  
2003 ◽  
Vol 57 (5) ◽  
pp. 533-538 ◽  
Author(s):  
P. Koc ◽  
M. Houka ◽  
B. Štok
Keyword(s):  
Inverse Problem ◽  
Moisture Content ◽  
Diffusion Coefficients ◽  
Moisture Diffusion ◽  
Transport Parameters ◽  
Moisture Flow ◽  
Identification Method ◽  
Three Samples ◽  
Computer Aided

Summary An inverse identification method for characterization of wood sorptive properties is presented. The method relies on a computer simulation of a real experiment, in our case a desorption experiment, where spruce heartwood samples were dried from 27% to 8% moisture content. Three samples, distinguished by the respective moisture flow pattern through the specimen, were investigated. A computer aided material characterization using the so-called inverse problem identification method was performed on the measurements. The solution of the specified inverse problem enabled us to estimate the moisture diffusion coefficients of wood and to determine the moisture content field in the sample simultaneously. The method is first verified on two simple cases of uniaxial moisture flow, and then is used to characterize the diffusion coefficients on a biaxial moisture flow sample. In the latter case some salient features of the proposed method are exhibited.

Prediction of Trifluralin Diffusion Coefficients

Weed Science ◽  
1973 ◽  
Vol 21 (5) ◽  
pp. 485-489 ◽  
Author(s):  
L. E. Bode ◽  
C. L. Day ◽  
M. R. Gebhardt ◽  
C. E. Goering
Keyword(s):  
Soil Moisture ◽  
Moisture Content ◽  
Diffusion Coefficients ◽  
Moisture Diffusion ◽  
Soil Parameters ◽  
Void Space ◽  
Exponential Relationship ◽  
Maximum Value ◽  
Soil Temperatures ◽  
Dry Soil

In the range of 4.4 to 49 C, there is an exponential relationship between temperature and trifluralin (α,α,α-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine) diffusion coefficients. Diffusion is low in air-dry soil for all temperatures. It increases to a maximum value when the soil has between 8 and 15% w/w soil moisture content and then decreases steadily as moisture content increases. When the air-filled fraction of soil void space is reduced below approximately 40% v/v by either compression or addition of moisture, diffusion begins to decrease. An equation was developed to predict trifluralin diffusion coefficients from a factorial experiment with seven soil moisture contents, five soil temperatures, and two bulk densities. Diffusion coefficients range from 3.8 X 10-11 cm2/sec to 2.8 X 10-6 cm2/sec. Fifteen terms are required in the prediction model to describe accurately the response surface of trifluralin diffusion coefficients. With the equation it is possible to predict trifluralin diffusion coefficients for any combination of measured soil parameters as long as they are represented by the range of the variables used in the experiment.

Comparison of moisture diffusion coefficients for pine, oak and linden wood

2016 ◽  
Vol 41 (2) ◽  
pp. 135-161 ◽  
Author(s):  
Zbigniew Perkowski ◽  
Jadwiga Świrska-Perkowska ◽  
Marek Gajda
Keyword(s):  
Diffusion Coefficient ◽  
Moisture Content ◽  
Diffusion Coefficients ◽  
Extreme Values ◽  
Quadratic Function ◽  
Moisture Diffusion ◽  
Pedunculate Oak ◽  
Emission Coefficient ◽  
Surface Emission ◽  
The Impact

This article presents experimental research on the moisture diffusivity in wood within the range of hygroscopic moisture. This research was carried out on samples of three types of trees: Scots pine, small-leaved linden and pedunculate oak. It included measurements of kinetics of moisture adsorption within the range of air relative humidity from 25% to 85%. For each type of wood, the experiment was carried out with unidirectional flow of moisture, in each of the material principal orthotropic directions, by examining the diffusion coefficient along the fibres, in the tangential direction and in the radial direction. Values of moisture diffusion coefficients and mass surface emission coefficient were found with the use of method of minimizing the objective function, that is, by fitting the computational adsorption kinetics curves to the experimental ones. At the same time, three cases of variations of the moisture diffusion coefficient together with moisture content of the material have been analysed each time: in the form of a constant, linear function and a quadratic function, assuming a constant value of mass surface emission coefficient on the absorbing surface of samples. The performed calculations allowed determining whether the moisture diffusion coefficients have extreme values within the analysed range of moisture content and what is the impact of various diffusion mechanisms on the whole process of transferring moisture in the considered cases.

scholarly journals Application of artificial intelligence in pancreaticobiliary diseases

2021 ◽  
Vol 14 ◽  
pp. 263177452199305
Author(s):  
Hemant Goyal ◽  
Rupinder Mann ◽  
Zainab Gandhi ◽  
Abhilash Perisetti ◽  
Zhongheng Zhang ◽  
...  
Keyword(s):  
Artificial Intelligence ◽  
Response To Treatment ◽  
Endoscopic Retrograde ◽  
Artificial Intelligence Techniques ◽  
Computer Aided ◽  
Rapid Pace ◽  
Cystic Pancreatic Lesions ◽  
Aided Diagnosis

The role of artificial intelligence and its applications has been increasing at a rapid pace in the field of gastroenterology. The application of artificial intelligence in gastroenterology ranges from colon cancer screening and characterization of dysplastic and neoplastic polyps to the endoscopic ultrasonographic evaluation of pancreatic diseases. Artificial intelligence has been found to be useful in the evaluation and enhancement of the quality measure for endoscopic retrograde cholangiopancreatography. Similarly, artificial intelligence techniques like artificial neural networks and faster region-based convolution network are showing promising results in early and accurate diagnosis of pancreatic cancer and its differentiation from chronic pancreatitis. Other artificial intelligence techniques like radiomics-based computer-aided diagnosis systems could help to differentiate between various types of cystic pancreatic lesions. Artificial intelligence and computer-aided systems also showing promising results in the diagnosis of cholangiocarcinoma and the prediction of choledocholithiasis. In this review, we discuss the role of artificial intelligence in establishing diagnosis, prognosis, predicting response to treatment, and guiding therapeutics in the pancreaticobiliary system.

scholarly journals Characterization of Moisture Diffusion in Cured Concrete Slabs at Early Ages

2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Xiao Zhang ◽  
Hongduo Zhao
Keyword(s):  
Process Model ◽  
Model Simulation ◽  
Moisture Diffusion ◽  
Experimental Results ◽  
Concrete Slabs ◽  
Model Parameters ◽  
Early Age ◽  
Water Curing ◽  
Early Age Concrete

The objective of this paper is to investigate the characterization of moisture diffusion inside early-age concrete slabs subjected to curing. Time-dependent relative humidity (RH) distributions of three mixture proportions subjected to three different curing methods (i.e., air curing, water curing, and membrane-forming compounds curing) and sealed condition were measured for 28 days. A one-dimensional nonlinear moisture diffusion partial differential equation (PDE) based on Fick’s second law, which incorporates the effect of curing in the Dirichlet boundary condition using a concept of curing factor, is developed to simulate the diffusion process. Model parameters are calibrated by a genetic algorithm (GA). Experimental results show that the RH reducing rate inside concrete under air curing is greater than the rates under membrane-forming compound curing and water curing. It is shown that the effect of water-to-cement (w/c) ratio on self-desiccation is significant. Lower w/c ratio tends to result in larger RH reduction. RH reduction considering both effect of diffusion and self-desiccation in early-age concrete is not sensitive to w/c ratio, but to curing method. Comparison between model simulation and experimental results indicates that the improved model is able to reflect the effect of curing on moisture diffusion in early-age concrete slabs.

A modular approach to computer-aided auscultation: Analysis and parametric characterization of murmur acoustic qualities

2013 ◽  
Vol 43 (6) ◽  
pp. 798-805 ◽  
Author(s):  
Chia-Hsuan Shen ◽  
Fred K. Choy ◽  
Yuerong Chen ◽  
Shengyong Wang
Keyword(s):  
Modular Approach ◽  
Computer Aided

ChemInform Abstract: Computer-Aided Characterization of Heterogeneous Catalyst Structure

ChemInform ◽  
2010 ◽  
Vol 25 (18) ◽  
pp. no-no
Author(s):  
J. M. NEWSAM ◽  
C. M. FREEMAN ◽  
S. M. LEVINE ◽  
M. W. DEEM
Keyword(s):  
Heterogeneous Catalyst ◽  
Catalyst Structure ◽  
Computer Aided

Direct Determination of Transport Parameters in Repository Materials

1992 ◽  
Vol 294 ◽  
Author(s):  
J. L. Conca ◽  
M.J. Apted ◽  
R.C. Arthur
Keyword(s):  
Diffusion Coefficients ◽  
Direct Determination ◽  
Advective Transport ◽  
Transport Parameters ◽  
Centripetal Acceleration ◽  
Compacted Bentonite ◽  
Diffusion Limited ◽  
Gradient Measurements ◽  
Time Required ◽  
Host Rocks

ABSTRACTA new flow technology has been developed that significantly decreases the time required to obtain transport data on saturated and unsaturated porous/fractured media. This technique is based on open-flow centrifugation and was developed to measure steady-state transport properties in most geologic materials within a matter of hours. Centripetal acceleration does not induce artificial effects in samples i.e., fracturing, collapse of interlayer structures, structural dewatering, compaction, chemical changes, etc., that occur with high-pressure methods. Using this technique, hydraulic conductivities (K) and diffusion coefficients (D) for compacted bentonite and four host rocks have been measured and re-interpreted. Based on these new data, K for compacted bentonite is less than 10−14 m/s, a factor of 1000 lower than previous pressure-gradient measurements, providing further assurance that radionuclide transport through bentonite backfill will be diffusion limited. Measured K for mudstone (1.8 × 10−12 m/s) indicates diffusion-limited far-field transport, while advective transport should occur for granite, basalt, and tuff, with expected matrix diffusion coefficients (correlated to measured D values) of 8.3 × 10−13 and 2.5 × 10−12 m2/s for fractured granite and basalt, respectively.

Boundary Surface Recovery From Skeleton Elements: Part I — Skeleton Curves

1992 ◽  
Author(s):  
Sean M. Gelston ◽  
Debasish Dutta
Keyword(s):  
Inverse Problem ◽  
Computer Aided Design ◽  
Boundary Surface ◽  
Reconstruction Algorithm ◽  
Companion Paper ◽  
Active Area ◽  
Curves And Surfaces ◽  
Computer Aided ◽  
Aided Design ◽  
Boundary Surfaces

Abstract Skeleton curves and surfaces have many applications in computer aided design and analysis. Construction of skeletons is an active area of research. We consider the inverse problem that of recovering boundary surfaces from given skeleton elements. The skeleton of any 3D object will, in general, consist of curves and surfaces. Therefore, any boundary reconstruction algorithm must systematically process the surfaces generated by the skeletal curves and the skeletal surfaces. In this paper (Part I) we present algorithms for reconstructing boundary surfaces corresponding to skeletal curves. Implemented examples are also included. In a companion paper (Part II) we consider skeletal elements that are surfaces.

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