Dynamic changes in spatial microbial distribution in mixed-population biofilms: Experimental results and model simulation

1995 ◽  
Vol 32 (8) ◽  
Keyword(s):  
Model Simulation ◽  
Mixed Population ◽  
Experimental Results ◽  
Dynamic Changes ◽  
Microbial Distribution

Dynamic changes in spatial microbial distribution in mixed-population biofilms: experimental results and model simulation

1995 ◽  
Vol 32 (8) ◽  
pp. 67-74 ◽  
Author(s):  
Satoshi Okabe ◽  
Kikuko Hirata ◽  
Yoshimasa Watanabe
Keyword(s):  
Oxygen Diffusion ◽  
Loading Rate ◽  
Model Simulation ◽  
Mixed Population ◽  
Experimental Results ◽  
Synthetic Wastewater ◽  
Diffusion Limitation ◽  
Dynamic Changes ◽  
Microbial Distribution ◽  
Rotating Biological Contactors

Dynamic changes in spatial microbial distribution in mixed-population biofilms were experimentally determined using a microslicer technique and simulated by a biofilm accumulation model (BAM). Experimental results were compared with the model simulation. The biofilms cultured in partially submerged rotating biological contactors (RBC) with synthetic wastewater were used as test materials. Experimental results showed that an increase of substrate loading rate (i.e., organic carbon and NH4-N) resulted in the microbial stratification in the biofilms. Heterotrophs defeated nitrifiers and dominated in the outer biofilm, whereas nitrifiers were diluted out in the outer biofilm and forced into the inner biofilm. At higher organic loading rates, a stronger stratified microbial spatial distribution was observed, which imposed a severe internal oxygen diffusion limitation on nitrifiers and resulted in the deterioration of nitrification efficiency. Model simulations described a general trend of the stratified biofilm structure. However, the actual stratification was stronger than the simulated results. For implication in the reactor design, when the specific carbon loading rate exceeds a certain limit, nitrification will be deteriorated or require a long start-up period due to the interspecies competition resulting in oxygen diffusion limitation. The extend of microbial stratification in the biofilm is especially important for determination of feasibility of nitrification in the presence of organic matters.

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.

Gas breakdown in the TCABR Tokamak: Model, simulation and experimental results

2001 ◽  
Author(s):  
Antonio M. M. Fonseca ◽  
Ruy P. da Silva ◽  
Ricardo M. O. Galvão ◽  
Yuri Kuznetzov ◽  
I. C. Nascimento ◽  
...  
Keyword(s):  
Model Simulation ◽  
Experimental Results ◽  
Gas Breakdown

The inverse square law in metrology considering a finite photosensitive area

2019 ◽  
Vol 52 (3) ◽  
pp. 407-412
Author(s):  
T Shibuya ◽  
K Kitaguchi ◽  
T Iwanaga
Keyword(s):  
Light Source ◽  
Model Simulation ◽  
High Accuracy ◽  
Experimental Results ◽  
Point Light Source ◽  
Inverse Square Law ◽  
Point Light ◽  
Photometric Distance

In the field of photometry, an inverse square law is often used in which the illuminance value is inversely proportional to the square of the photometric distance. It is well known that this is a rule that assumes that the light source is a point light source. In this research, it is shown by model simulation that the inverse square law cannot be applied with high accuracy depending on the distance and the size of the light-receiving area even in the case of a point light source. Also, when checked experimentally, the experimental results agree well with the simulation.

Model simulation of single-breath washout of insoluble gases from dog lungs

1985 ◽  
Vol 58 (3) ◽  
pp. 802-811 ◽  
Author(s):  
C. Hook ◽  
M. Meyer ◽  
J. Piiper
Keyword(s):  
Experimental Data ◽  
Gas Transport ◽  
Model Simulation ◽  
Experimental Results ◽  
Gas Mixing ◽  
Operational Model ◽  
Alveolar Plateau ◽  
Single Breath ◽  
And Diffusion

Intrapulmonary gas mixing by convection and diffusion is analyzed on the basis of various analog lung models incorporating singly or in combination series inhomogeneity, parallel inhomogeneity, intercompartmental diffusion, sequential inspiration, and sequential expiration. The slope of the alveolar plateau of insoluble gases is used as an indicator for incomplete gas mixing. By use of the models, we have attempted to simulate experimental results obtained in artificially ventilated dog lungs with simultaneous single-breath washout of He and SF6 (Meyer et al., J. Appl. Physiol. 55: 1795–1802, 1983). Sufficient agreement with experimental data is obtained only when diffusion between serial-parallel compartments and sequential expiration are incorporated, the first being mainly responsible for separation of He and SF6, the latter for the slope of the alveolar plateau of these gases. A combined operational model comprising two parallel compartments connected to a mixing compartment, with both convective and diffusive gas transport between the compartments, could account for most of the experimental observations.

scholarly journals RESEARCH INTO RAIL SIDE WEARING ON CURVES

Transport ◽  
2003 ◽  
Vol 18 (3) ◽  
pp. 124-129 ◽  
Author(s):  
Inesa Povilaitienė ◽  
Igoris Podagėlis
Keyword(s):  
Experimental Research ◽  
Experimental Results ◽  
Geometrical Parameters ◽  
Dynamic Changes ◽  
Rail Track ◽  
Railway Line ◽  
Factors Influencing ◽  
Measurement Results

Factors influencing rail side wearing in the curves are described in the article. All of them are divided into uncontrolled, partially controlled and controlled. An experiment was carried out on Lithuanian railway line curves. The experiment proceeding conditions and the obtained results are presented. The object of the experimental research is 19 curves. The investigations of dynamic changes in rail wearing and in rail track geometrical parameters on curves were being carried out for one and a half year. The experimental results, associated with the railway gauge influence on rail wearing on curves are analyzed more precisely. Measurement results are described using mathematical dependences. According to the dependences it is possible to estimate the influence of gauge on rail side wearing on curves.

Vibration Reduction of a Vision-Based Controlled Flexible Arm: Theoretical and Experimental Aspects

2005 ◽  
Author(s):  
Shuxin Wang ◽  
Bingquan Wen ◽  
Hongbo Yu ◽  
Jintian Yun
Keyword(s):  
Dynamic Models ◽  
Controller Design ◽  
Model Simulation ◽  
Sampling Rate ◽  
Experimental Results ◽  
Control Input ◽  
Actual System ◽  
Flexible Arm ◽  
Two Factors ◽  
Measured Position

For vision-based controlled flexible arm, the accuracy of the finite dimensional dynamic models and stability become very important for controller design. This paper addresses the issue of selecting the shape function and mode in developing finite dynamic models, and designs suitable controller for a flexible arm with vision-based control. Input of the controller is the measured position error of the beam tip, which can be directly obtained by camera. In spite of the observed differences between actual system and simulated system, experimental results are good enough to validate the arm model. Simulation and experimental results show that the PID controller is acceptable. It is also stressed that two factors, the camera sampling rate and a dead band in the velocity command, will influence the properties of the control system for vision-based controlled flexible arm.

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