L’objectif de ces travaux de thèse est d’étudier l’influence du rapport entre taille de défaut et longueur caractéristique de la microstructure, sur la limite de fatigue pour une durée de vie fixée d’un matériaux métallique,dans le cadre de la fatigue à grand nombre de cycle (FGNC). Le fer pur Armco est choisi comme matériau d’étude, car sa microstructure simple présente une seule longueur caractéristique à l’échelle mésoscopique (échelle des grains) : la taille de grain. Le but de l’étude revient ainsi à étudier la compétition entre un effet de structure (défaut surfacique)et un effet matériau (taille de grain) dans le cadre de sollicitations mécaniques en FGNC.Afin d’obtenir une taille de défaut comparable mais aussi inférieure à la taille de grain du matériau, un protocole thermomécanique a été élaboré pour augmenter la taille de grain. Des essais de FGNC, utilisant des éprouvettes issues des deux tailles de microstructures (matériau initial et celui écroui traité) dans lesquelles sont introduits des défauts hémisphériques de tailles différentes, ont été effectués pour estimer les limites de fatigue pour différents rapports taille de défaut / taille de grain. Lorsque les diagrammes de Kitagawa sont présentés en valeurs relatives(limite de fatigue / celle du matériau sans défaut en fonction de la taille de défaut / taille de grain), il existe une seule courbe qui combine les deux microstructures. Ce diagramme de Kitagawa sans dimension permet ainsi d’analyser la réduction de la limite de fatigue causée par un défaut. L’utilisation de la taille relative du défaut par rapport à la dimension microstructurale caractéristique apparaît comme plus pertinente que l’emploi de la taille physique réelle du défaut.Ces résultats expérimentaux sont utilisés pour reproduire les essais en FGNC avec des simulations Éléments Finis sur des microstructures 3D représentatives du fer Armco. La compétition existant entre la concentration de contrainte induite par le défaut géométrique et les régions fortement sollicitées de la microstructure engendrées parl’anisotropie du comportement mécanique des grains est étudiée. Un critère mésoscopique (à partir des grandeurs mécaniques moyennées par grain) basé sur une approche statistique permet de retrouver l’allure du diagramme de Kitagawa adimensionné, c’est-à-dire la taille relative du défaut critique à partir de laquelle ce dernier prend le passur l’hétérogénéité de la réponse de la microstructure et conditionne ainsi la tenue en fatigue du polycristal. La modification du critère mésoscopique par la prise en compte des hétérogénéités intragranulaires (via l’écart-type par grain des grandeurs mécaniques) est discutée. / The objective of this thesis is to study the influence of the ratio between the defect size and themicrostructure characteristic length on the fatigue limit (for a fixed fatigue life) of a metallic material, under highcycle fatigue (HCF). Pure Armco iron is chosen because its simple microstructure has a single characteristic lengthat the mesoscopic scale (grain scale) : the grain size. The aim of the study is thus to study the competition betweena structural effect (surface defect) and a material effect (grain size) in the context of mechanical stresses in HCF.In order to obtain a comparable different grain size, a thermomechanical protocol has been developed. HCF tests,using specimens from both microstructure sizes (initial material and processed hardened material) in which hemisphericaldefects of different sizes were introduced, were performed to estimate the fatigue limits for different defectsize / grain size ratios. When Kitagawa diagrams are presented in relative values (fatigue limit / fatigue limit ofdefect free material versus defect size / grain size), there is a single curve that combines the two microstructures.This dimensionless Kitagawa diagram thus makes it possible to analyze the reduction of the fatigue limit inducedby a defect. The use of the relative size of the defect with respect to the characteristic microstructural dimensionappears to be more relevant than the use of the physical size of the defect.These experimental results are used to reproduce the HCF tests with Finite Element simulations on 3D microstructuresrepresentative of Armco iron. The competition existing between the stress concentration induced by thegeometrical defect and the highly stressed regions of the microstructure generated by the anisotropy of the mechanicalbehavior of the grains is studied. A mesoscopic criterion (involving mechanical quantities averaged by grain)based on a statistical approach allows to find the evolution of the dimensionless Kitagawa diagram, ie the relativesize of the critical defect from which it predominates over the response heterogeneity of the microstructure and thusgoverns the fatigue behavior of the polycrystal. The modification of the mesoscopic criterion by taking into accountintragranular heterogeneities (with the standard deviation per grain of mechanical quantities) is discussed.

Waterways have been geomorphically altered or disturbed by development, mining, agriculture and other human activities for many years. Section 404 of the Clean Water Act determined that these impacts to our waterways must be mitigated for channel alterations. Stream restoration has been one method to mitigate for these impacts to our water resources. Stream restoration is considered to be a measurable improvement to the channel stability, water quality, habitat or overall function of a degraded stream system. Practices of stream restoration have changed in the last 10 to 20 years with the introduction of natural channel design methods. Natural channel design involves rebuilding a stream channel with the appropriate channel dimensions, slope, and planform to accommodate water and sediment inputs from its drainage basin without excessively aggrading or degrading. Dimensions of restored stream channels are based on a stage that is termed bankfull. The bankfull discharge is the flow that fills the channel just to the tops of its banks to the incipient point of flooding. Design dimensions used in natural channel design are based on bankfull stage and discharge because practitioners believe it is responsible for the average morphology of a stream channel. Practitioners of stream restoration use two tools to aid in the determination of these stable channel conditions: they are 1) regional channel geometry and discharge relations to drainage area (regional curves) and 2) reference reach derived dimensionless bankfull channel geometry ratios. These tools are developed for ecoregions that have similar climates, topography, geology, soils, hydrology and vegetation because these are also the features that dictate stream channel form. Regional curves and reference reach dimensionless ratios were developed for the Level III Ecoregion 67 Ridge and Valley, Tennessee. The regional power function equations of bankfull cross sectional area, width, mean depth, and discharge to drainage, and the dimensionless bankfull channel geometry ratios of reference reaches will help determine the bankfull channel dimensions used in natural channel design.

Knowledge of the turbulent fluxes at the sea surface is important for understanding the interaction between atmosphere and ocean. With better knowledge, improvements in the estimation of the heat exchange coefficients can be made and hence models are able to predict the weather and future climate with higher accuracy. The exchange coefficients of latent and sensible heat during stable stratification vary in the literature. Therefore it is necessary to investigate the processes influencing the air-sea exchange of water vapour and heat in order to estimate these values. With measurements from a tower and a directional waverider buoy at the site Östergarnsholm in the Baltic Sea, data used in this study have been sampled from the years 2005-2007. This site represents open-ocean conditions during most situations when the wind comes from the south-east sector. The neutral exchange coefficients, CEN and CHN, have been calculated along with the non-dimensional profile functions for temperature and wind to study the dependence of stability and other parameters of relevance. It was found that CEN increased slightly with wind speed and reached a mean value of approximately 1.45×10-3. The highest values of CEN were observed during near neutral conditions and low wave ages. CHN attained a mean value of approximately 0.77×10-3 and did not show any relation to wind speed or to wave age. No significant dependence with wind or wave direction could be shown for either CEN or CHN in the sector 80-220°. The stability correction, performed to reduce the dependence on stratification for CEN and CHN, was well performed for stabilities higher than 0.15. The stability is represented by a relationship between the height and the Obukhov-length (z/L). Validity of the non-dimensional profile functions for temperature and wind showed that, for smaller stabilities, these functions gave higher values than the corresponding functions recommended by Högström (1996). The profile funtions for temperature was shown to have a larger scatter while the profile functions for wind was less scattered and deviated more from the functions given by Högström / Kunskap om turbulenta flöden i det marina gränsskiktet är viktigt för att förstå växelverkan mellan atmosfär och hav. Med bättre kunskap kan förbättringar i bestämningen av utbyteskoefficienterna för latent och sensibelt värme erhållas. Det medför att modeller kan prognostisera väder och framtida klimat med högre noggrannhet. Utbyteskoefficienterna för latent och sensibelt värme har för stabil skiktning olika värden i litteraturen. Detta gör det nödvändigt att undersöka de processer som påverkar utbytet av vattenånga och värme mellan luft och hav för att kunna bestämma dessa värden. Data som har använts i den här studien insamlades mellan år 2005 och 2007 från en boj och ett torn vid mätplatsen Östergarnsholm i Baltiska havet. För det flesta situationer, när vinden blåser från syd-ost, representerar mätplatsen ett förhållande likvärdigt det över öppet hav. De neutrala utbyteskoefficienterna, CEN och CHN, och de dimensionslösa profilfunktionera för temperatur och vind, och , har beräknats för att studera beroendet av stabilitet samt andra relevanta parametrar. Beräkningarna visade att CEN ökade något med vindhastighet och hamnade på ett medelvärde av ungefär 1.45×10-3. De högsta värdena på CEN observerades vid nära neutrala förhållanden och låga vågåldrar. CHN uppmättes till att ha ett medelvärde på ungefär 0.77×10-3 och uppvisade inget beroende med vindhastighet eller vågålder. Inget märkbart beroende med vind- eller vågriktning kunde visas för CEN eller CHN i sektorn 80-220°. Stabilitetskorrektionen, utförd för att reducera beroendet av atmosfärens skiktning för CEN och CHN, var bra för stabiliteter högre än 0.15. Stabiliteten representeras av förhållandet mellan höjden och Obukhov-längden (z/L). Utvärdering av de dimensionslösa funktionerna för temperatur och vind visade att dessa funktioner, för små stabiliteter, gav högre värden än motsvarande funktioner som rekommenderas av Högström (1996). Värdena på profilfunktionerna för temperatur hade större spridning än värdena på profilfunktionerna för vind och avvek mer från funktionerna givna av Högström.

Solid oxide fuel cells (SOFCs) are high temperature (600C-1000C) composite metallic/ceramic-cermet electrochemical devices. There is a need to effectively manage the heat transfer through the cell to mitigate material failure induced by thermal stresses while yet preserving performance. The present dissertation offers a novel thermodynamic optimization approach that utilizes dimensionless geometric parameters to design a SOFC. Through entropy generation minimization, the architecture of a planar SOFC has been redesigned to optimally balance thermal gradients and cell performance. Cell performance has been defined using the 2nd law metric of exergetic efficiency. One constrained optimization problem was solved. The optimization sought to maximize exergetic efficiency through minimizing total entropy production while constraining thermal gradients. Optimal designs were produced that had exergetic efficiency exceeding 92% while maximum thermal gradients were between 219 C/m and 1249 C/m. As the architecture was modified, the magnitude of sources of entropy generation changed. Ultimately, it was shown that the architecture of a SOFC can be modified through thermodynamic optimization to maximize performance while limiting thermal gradients. The present dissertation highlights a new design methodology and provides insights on the connection between thermal gradients, performance, sources of entropy generation, and cell architecture.

This research report examines the use of zone modelling compared with CFD modelling to determine when zone model approximation is valid and when a CFD model might be required. A series of computer simulations with enclosures and fires of various sizes was performed to compare the capabilities and limitations of the two computer methods. The relationship between the size of the enclosure space and the size of the fire has been demonstrated in a dimensionless form. The zone model BRANZFIRE and the CFD model FDS were used for simulating smoke development. The simulations included various full-scale experimental data on both small and large spaces found in the literature. Further simulations of large exemplar spaces with a range of fire sizes were performed to investigate different variables, which have not been examined in full-scale experiments. The simulation results have been compared based on the smoke layer height and the average layer temperature. Zukoski’s smoke filling equation was also used to compare the layer height predictions against BRANZFIRE and FDS. It was found that different data reduction techniques gave different approximations to the layer height. A perfect match between the experimental data and the model output was very difficult to achieve. FDS showed a large uncertainty of the smoke layer height and temperature in the early stages of fire across the enclosure space. In the later stages, this uncertainly became minimised where the smoke layer height and temperature were fairly uniformly developed across the space. For fire enclosures with instantaneous steady-state fires, the predictions between BRANZFIRE and FDS agreed well with each other if the fire size and the enclosure size were within a reasonable range. From the modelling of the full-scale experiments, FDS showed favourable layer-height comparisons against the full-scale experimental tests. However, the output results from BRANZFIRE are less comparable with those of FDS for the experiments with fire growth. An appropriate smoke transport time lag should be included for Zukoski’s smoke filling equation and BRANZFIRE; otherwise, they gave conservative estimates of the layer height to smaller fires with a growth phase. In general, the data reduction methods and zone models should not be used if the fire is too small relative to the enclosure size. A very low temperature rise within the enclosure space would give invalid predictions of the layer height and average layer temperature. This is because there is no clear indication of a separation between the upper and lower smoke layers or temperatures. Single point data of smoke concentrations and temperatures from CFD models should be considered through the entire space or at the specified location of interest. This also applies to an extremely large fire relative to the enclosure size where temperature distribution across the space might not be very homogenous. CFD models could also be used to investigate the details of the smoke properties in the early stages of growing fires, in which the smoke transport lag and the plume effects cannot be seen in BRANZFIRE. This research is intended to provide guidance for fire engineers by determining which of the computer methods can be used confidently and appropriately as a design tool.

The diploma thesis aims to establish thermo-hydraulic properties of a flexible tube described by its Darcy friction factor and film heat transfer coefficient respectively. A flexible tube (corrugated stainless steel tube) is an easily shapeable stainless steel component used to build various piping connections, in a place of more common copper or plastic made tubes. It can also be used to build heat exchangers thanks to its signature properties. The investigated product is the one developed and manufactured by the Czech company Flexira s.r.o. and sold under the brand name xConnect System. Its thermo-hydraulic properties are established by an experiment, which is based on real utilizations by Laboratory of Energy Intensive Processes in NETME (New Technologies for Mechanical Engineering) Centre at Brno University of Technology. The investigated case is a coil-shaped element serving a purpose of a water-to-water heat exchanger. The text contains a literature survey of the chosen flexible tube and a description of a draft and development of the specific experimental test based off the established theory. The obtained results are then analysed, for the purpose of establishing a functional dependence, which can then be used to calculate a film heat transfer coefficient.

La simulation des transferts couplés de chaleur et de masse dans l’enveloppe du bâtiment est une pratique qui se démocratise de plus en plus. Pour les bâtiments construits avec des matériaux très hygroscopiques, l'évaluation correcte des champs de température et d’humidité est importante pour prédire avec précision les flux de chaleur et d'humidité, le confort hygrothermique et la consommation énergétique des bâtiments. En outre, l'humidité peut causer des dommages aux matériaux de construction et a un impact sur la santé des occupants. Pour les matériaux très hygroscopiques, les outils de simulation ont montré des lacunes à modéliser correctement le comportement hygrothermique. Sur ces questions, le projet de recherche HYGRO-BAT est un projet fédérateur. Dans ce contexte, nous avons développé un modèle suffisamment fin de transfert couplé de Chaleur, d’Air et d’Humidité (CAH) qui permet l’analyse des principaux phénomènes physiques mis en jeu. Afin de valider le modèle développé et d’étudier en détail le comportement hygrothermique d’une paroi très hygroscopique, nous avons conçu et réalisé un outil expérimental avec une instrumentation riche et variée permettant de simuler les contraintes rencontrées dans le cas réel. Le choix des sollicitations hygrothermiques retenues permet une compréhension progressive du modèle. De surcroît, pour simplifier l’analyse des mécanismes de transfert couplés au sein de la paroi, une formulation adimensionnée du modèle développé a été proposée, permettant ainsi de mettre en avant des nombres adimensionnels qui simplifient l’analyse du comportement d’une paroi très hygroscopique. Ces nombres permettent une nouvelle caractérisation représentative des mécanismes de transfert qui dépendent de l’état thermodynamique de la paroi / Simulation of Heat, Air and Moisture (HAM) transfers in building envelope is a practice which is becoming increasingly popular. The correct evaluation of temperature and moisture fields is important to predict accurately heat and moisture fluxes, hygrothermal comfort and building energy consumption, especially for highly hygroscopic materials. Additionally, moisture has an impact on the health of occupants and can causes damage to building materials. For highly hygroscopic materials, simulation models show discrepancy to the real hygrothermal behavior. The research project HYGRO-BAT is a unifying project on these issues. In this context, we developed a hygrothermal transfer model sufficiently fine allowing the analysis of the main physical phenomena involved. In order to validate the developed model and to study in detail the coupled heat and mass transfers for highly hygroscopic walls, we designed and realized an experimental tool that allows numerous and various measurement and creating climates encountered for building application. The choice of hygrothermal loading allows progressive understanding of involved physical mechanisms in the envelope. Moreover, to simplify the analysis, a dimensionless hygrothermal formulation was proposed. It allows highlighting dimensionless numbers which are very convenient to study the behavior of a very hygroscopic wall. These numbers allow a new representative characterization of transfer mechanisms that rely on the thermodynamic state of the wall

Biological filtration (Biofiltration) processes have been used first in Europe and then in North America for decades, however currently there is not a good overall parameter to guide biofiltration design and operation except adopting parameters from traditional particle- removal filtration process. On the basis of the biofilm model developed by Rittmann and McCarty (1980a) and the pseudo-analytical solution for the model, Zhang and Huck (1996a) obtained an analytical solution for PF (plug flow) reactors (which can be used for biofilters approximately) after demonstrating that axial dispersion could be reasonably ignored and developed a new parameter, X*, which incorporates considerations of physical contact time, filter media particle size, kinetics, etc. A small-scale application on peers’ engineering/research data by Huck (1999) demonstrated it was a better indicator than other parameters for biofiltration performance. By collecting, screening and investigating literature on AOC, BDOC and odorous compounds removal by biofiltration process, this thesis applied the X* concept to the collected investigations to assess process performances among different target parameters, different filters and different investigations. To the author’s knowledge, this is the first such attempted comprehensive comparison of literature studies, interpreted in terms of a common parameter (X*). The wide ranges of particle sizes, EBCTs, temperatures and high diversity of pre-treatment and operation conditions for the collected cases were considered to be able to well represent biofiltration practices for studied removal targets. No significant relationship between EBCTs and removal percentages were found, indicating that EBCT alone is not able to guide biofiltration design and operation. Based on kinetics parameter comparison, BDOC removal-X* relationship was established. A new parameter, θα, was developed in this thesis to refer to estimated X* values only considering EBCT and particle size. θα parameter values were estimated by comparison of ratios of θα products ((θα)’) based on the properly chosen calculation bases. Distribution of the θα values for temperature-favored (i.e. temperature ≥15°C) AOC and BDOC removal biofiltration processes matched the established removal-X* relationship reasonably. Given the exploratory nature of this research and the complexity of attempting quantitations, fits were assessed based on visual comparison. With the assistance of supporting information and by adopting available temperature activity coefficients, temperature-adjustment coefficients for θα values were determined for the different temperature ranges. Temperature-adjusted AOC and BDOC removal-θα relationships were developed and temperature-adjusted θα parameter values for AOC and BDOC removal were also estimated. Comparisons were conducted, showing fair matches based on visual examinations, for most of the temperature ranges. No relationships were found between ozone dosages and AOC/BDOC removal percentages and the statistical analysis indicated there was significant difference of removal efficiencies between ozonated and non-ozonated influents for biofilters, suggesting ozonation may not only increase the amount of BOM for following biofilter and increase the biodegradability of bulk water; it may also increase the biodegradability of AOC and BDOC themselves. It may not be realistic to obtain the estimated θα values for MIB and geosmin removal by biofiltration. However, plotting θα product vs. removal percentage for the collected MIB and geosmin removal cases shows more positive co-relationships than EBCT-removal percentage relationships visually. A utilization factor η was proposed to guide biofilter design and operation and to assess “over-design” and “under-operated”. Biofilter over-design or under-operated is common for the collected cases. In general, examining X* (or θα, a parameter incorporating the physical components of X*) provided useful information in terms of evaluation and prediction of biodegradable organic compounds removal by biofiltration, which confirms that X* is a better parameter for biofiltration design and operation than other parameters, such as EBCT.

Biological filtration (Biofiltration) processes have been used first in Europe and then in North America for decades, however currently there is not a good overall parameter to guide biofiltration design and operation except adopting parameters from traditional particle- removal filtration process. On the basis of the biofilm model developed by Rittmann and McCarty (1980a) and the pseudo-analytical solution for the model, Zhang and Huck (1996a) obtained an analytical solution for PF (plug flow) reactors (which can be used for biofilters approximately) after demonstrating that axial dispersion could be reasonably ignored and developed a new parameter, X*, which incorporates considerations of physical contact time, filter media particle size, kinetics, etc. A small-scale application on peers’ engineering/research data by Huck (1999) demonstrated it was a better indicator than other parameters for biofiltration performance. By collecting, screening and investigating literature on AOC, BDOC and odorous compounds removal by biofiltration process, this thesis applied the X* concept to the collected investigations to assess process performances among different target parameters, different filters and different investigations. To the author’s knowledge, this is the first such attempted comprehensive comparison of literature studies, interpreted in terms of a common parameter (X*). The wide ranges of particle sizes, EBCTs, temperatures and high diversity of pre-treatment and operation conditions for the collected cases were considered to be able to well represent biofiltration practices for studied removal targets. No significant relationship between EBCTs and removal percentages were found, indicating that EBCT alone is not able to guide biofiltration design and operation. Based on kinetics parameter comparison, BDOC removal-X* relationship was established. A new parameter, θα, was developed in this thesis to refer to estimated X* values only considering EBCT and particle size. θα parameter values were estimated by comparison of ratios of θα products ((θα)’) based on the properly chosen calculation bases. Distribution of the θα values for temperature-favored (i.e. temperature ≥15°C) AOC and BDOC removal biofiltration processes matched the established removal-X* relationship reasonably. Given the exploratory nature of this research and the complexity of attempting quantitations, fits were assessed based on visual comparison. With the assistance of supporting information and by adopting available temperature activity coefficients, temperature-adjustment coefficients for θα values were determined for the different temperature ranges. Temperature-adjusted AOC and BDOC removal-θα relationships were developed and temperature-adjusted θα parameter values for AOC and BDOC removal were also estimated. Comparisons were conducted, showing fair matches based on visual examinations, for most of the temperature ranges. No relationships were found between ozone dosages and AOC/BDOC removal percentages and the statistical analysis indicated there was significant difference of removal efficiencies between ozonated and non-ozonated influents for biofilters, suggesting ozonation may not only increase the amount of BOM for following biofilter and increase the biodegradability of bulk water; it may also increase the biodegradability of AOC and BDOC themselves. It may not be realistic to obtain the estimated θα values for MIB and geosmin removal by biofiltration. However, plotting θα product vs. removal percentage for the collected MIB and geosmin removal cases shows more positive co-relationships than EBCT-removal percentage relationships visually. A utilization factor η was proposed to guide biofilter design and operation and to assess “over-design” and “under-operated”. Biofilter over-design or under-operated is common for the collected cases. In general, examining X* (or θα, a parameter incorporating the physical components of X*) provided useful information in terms of evaluation and prediction of biodegradable organic compounds removal by biofiltration, which confirms that X* is a better parameter for biofiltration design and operation than other parameters, such as EBCT.

Magistrinio darbo tikslas yra sukurti kompiuterinį amperometrinio biojutiklio su chemiškai modifikuotu elektrodu modelį ir ištirti jo savybes. Modelis papildo egzistuojančius modelius mediatoriaus sluoksniu. Mediatoriaus koncentracija sluoksnyje nėra konstanta, tirpsta biojutiklio veikimo eigoje. Darbe apžvelgiama medžiaga apie amperometrinius biojutiklius, biojutiklio modeliavimo aspektus, mediatoriaus tirpimo priežastis ir veikimo principus. Vėliau suformuluojamas pasirinkto biojutiklio matematinis modelis. Matematiniame modelyje pateikiamos diferencialinės lygtys su dalinėmis išvestinėmis, aprašančios biojutiklyje vykstančias reakcijas ir difuzijas. Pagal matematinį modelį yra sudaromas skaitinis modelis. Pagal žinomus analizinius sprendimus modelis yra ratifikuojamas. Remiantis skaitiniu modeliu buvo sukurta programinė įranga įgyvendinanti diferencialinių lygčių su dalinėmis išvestinėmis sprendimo metodą (išreikštinę baigtinių skirtumų schemą) ir simuliuojanti biojutiklio veikimą. Programinė įranga yra karkasas, leidžiantis nagrinėti sumodeliuoto biojutiklio savybes bei charakteristikas. Buvo ištirtos substrato ir mediatoriaus koncentracijų, mediatoriaus, fermento, difuzijos sluoksnių, bei mediatoriaus sluoksnio difuzijos koeficiento įtakos biojutiklio generuojamos srovės tankiui. Be to gauti dviejų modelių palyginimo rezultatai parodė sumodeliuoto biojutiklio modelio skirtumus ir panaudojimo prasmingumą. / The aim of master thesis is to model amperometric biosensor with chemically modified electrode, introducing into existing model one more additional mediator layer. Mediator concentration inside the layer is changing during the biosensor action. Master thesis content consists of: enzyme kinetics introduction, biosensor modeling peculiarities exploration, chemically modified electrode information, biosensor action aspects description. Following chapter concentrates on mathematical modeling of particular biosensor type. Mathematical model represents differential equations with partial derivatives describing the reactions and diffusion inside biosensor. Next, numerical model is formulated. The explicit method technique was used. Based on numerical model software was made and validated. Using software the biosensor action was simulated in order to investigate biosensor properties and characteristics. In this work several properties were analyzed: impact of substrate and mediator concentrations, size of mediator, enzyme and diffusion layers, mediator layer diffusion coefficient on biosensor response. This model was compared with previous introduced model and it was shown that there is some difference between them and there is a reason to use new model.