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Статті в журналах з теми "Partial interaction mechanics"
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Xu, Rongqiao, and Dequan Chen. "Variational Principles of Partial-Interaction Composite Beams." Journal of Engineering Mechanics 138, no. 5 (May 2012): 542–51. http://dx.doi.org/10.1061/(asce)em.1943-7889.0000364.
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Oehlers, Deric J., Phillip Visintin, Jian-Fei Chen, Rudolf Seracino, Yufei Wu, and Wade Lucas. "Reinforced Concrete Behavior, Research, Development, and Design through Partial-Interaction Mechanics." Journal of Structural Engineering 143, no. 7 (July 2017): 02517002. http://dx.doi.org/10.1061/(asce)st.1943-541x.0001764.
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Zhang, Tao, Phillip Visintin, and Deric J. Oehlers. "Partial-interaction tension-stiffening properties for numerical simulations." Advances in Structural Engineering 20, no. 5 (July 19, 2016): 812–21. http://dx.doi.org/10.1177/1369433216660654.
Повний текст джерелаАнотація:
The partial-interaction behaviour of tension-stiffening affects or controls virtually all aspects of reinforced concrete member behaviour as it controls the formation and widening of cracks as well as the load developed within the reinforcement crossing a crack. In this article, simple closed-form solutions for the tension-stiffening behaviour of reinforced concrete prisms are derived through mechanics and are presented in a form that can be easily used in both displacement-based and strain-based numerical modelling. This research quantifies not only the pseudo material properties of tension-stiffening such as equivalent stress–strain relationships or equivalent moduli that simulate the increase in reinforcement stiffness associated with tension-stiffening but also the crack spacings and crack widths. It is shown that the bond properties have little, if any, effect on tension-stiffening but a major effect on crack spacings and widths.
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Turmo, J., J. A. Lozano-Galant, E. Mirambell, and D. Xu. "Modeling composite beams with partial interaction." Journal of Constructional Steel Research 114 (November 2015): 380–93. http://dx.doi.org/10.1016/j.jcsr.2015.07.007.
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Siu, W. H., and R. K. L. Su. "Analysis of side-plated reinforced concrete beams with partial interaction." Computers & concrete 8, no. 1 (February 25, 2011): 71–96. http://dx.doi.org/10.12989/cac.2011.8.1.071.
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Jeong, Youn-Ju, Hyeong-Yeol Kim, and Sang-Hyo Kim. "Partial-interaction analysis with push-out tests." Journal of Constructional Steel Research 61, no. 9 (September 2005): 1318–31. http://dx.doi.org/10.1016/j.jcsr.2005.01.010.
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Allam, Mehter M., Kanakapura S. Subba Rao, and B. V. V. Subramanya. "Partial Loss of Support and Frame‐Soil Interaction." Journal of Structural Engineering 113, no. 12 (December 1987): 2488–99. http://dx.doi.org/10.1061/(asce)0733-9445(1987)113:12(2488).
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Bradford, Mark Andrew, and R. Ian Gilbert. "Composite Beams with Partial Interaction under Sustained Loads." Journal of Structural Engineering 118, no. 7 (July 1992): 1871–83. http://dx.doi.org/10.1061/(asce)0733-9445(1992)118:7(1871).
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Sturm, Alexander B., Phillip Visintin, and Deric J. Oehlers. "Time-dependent serviceability behavior of reinforced concrete beams: Partial interaction tension stiffening mechanics." Structural Concrete 19, no. 2 (August 29, 2017): 508–23. http://dx.doi.org/10.1002/suco.201700021.
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Lu, Pengzhen, and Changyu Shao. "A new model for composite beams with partial interaction." Proceedings of the Institution of Civil Engineers - Engineering and Computational Mechanics 167, no. 1 (March 2014): 30–40. http://dx.doi.org/10.1680/eacm.12.00015.
Повний текст джерелаДисертації з теми "Partial interaction mechanics"
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Philipowski, Robert. "Stochastic interacting particle systems and nonlinear partial differential equations from fluid mechanics." [S.l.] : [s.n.], 2007. http://deposit.ddb.de/cgi-bin/dokserv?idn=986005622.
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Stamm, Matthew T. "Particle Dynamics and Particle-Cell Interaction in Microfluidic Systems." Diss., The University of Arizona, 2013. http://hdl.handle.net/10150/308886.
Повний текст джерелаАнотація:
Particle-laden flow in a microchannel resulting in aggregation of microparticles was investigated to determine the dependence of the cluster growth rate on the following parameters: suspension void fraction, shear strain rate, and channel-height to particle-diameter ratio. The growth rate of an average cluster was found to increase linearly with suspension void fraction, and to obey a power-law relationships with shear strain rate as S^0.9 and channel-height to particle-diameter ratio as (h/d)^-3.5. Ceramic liposomal nanoparticles and silica microparticles were functionalized with antibodies that act as targeting ligands. The bio-functionality and physical integrity of the cerasomes were characterized. Surface functionalization allows cerasomes to deliver drugs with selectivity and specificity that is not possible using standard liposomes. The functionalized particle-target cell binding process was characterized using BT-20 breast cancer cells. Two microfluidic systems were used; one with both species in suspension, the other with cells immobilized inside a microchannel and particle suspension as the mobile phase. Effects of incubation time, particle concentration, and shear strain rate on particle-cell binding were investigated. With both species in suspension, the particle-cell binding process was found to be reasonably well-described by a first-order model. Particle desorption and cellular loss of binding affinity in time were found to be negligible; cell-particle-cell interaction was identified as the limiting mechanism in particle-cell binding. Findings suggest that separation of a bound particle from a cell may be detrimental to cellular binding affinity. Cell-particle-cell interactions were prevented by immobilizing cells inside a microchannel. The initial stage of particle-cell binding was investigated and was again found to be reasonably well-described by a first-order model. For both systems, the time constant was found to be inversely proportional to particle concentration. The second system revealed the time constant to obey a power-law relationship with shear strain rate as τ∝S^.37±.06. Under appropriate scaling, the behavior displayed in both systems is well-described by the same exponential curve. Identification of the appropriate scaling parameters allows for extrapolation and requires only two empirical values. This could provide a major head-start in any dosage optimization studies.
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Zhang, Yonghao. "Particle-gas interactions in two-fluid models of gas-solid flows." Thesis, University of Aberdeen, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.367375.
Повний текст джерелаАнотація:
Modelling gas-solid two-phase flows using a two-fluid approach has two main difficulties: formulating constitutive laws for the particulate stresses and modelling the gas turbulence modulation. Due to the complex nature of the gas-particle interactions, there is no universal model covering every flow regime. In this thesis, three flow regimes with distinctive characteristics are studied, i.e. the very dense regime where the solid volume fraction, v2>5%, the dense flow regime where 5%≥1%, and the relatively dilute regime where 1%≥v2>0.1%. In the very dense flow regime, where the interstitial gas is normally neglected, the gas flow is assumed laminar and causes a viscous energy dissipation in the particulate phase. Numerical results for granular materials flowing down an inclined chute show that the interstitial gas may have a considerable effect in these flows. In the dense regime, where the inter-particle collisions are very important, a fluctuational energy transfer rate between the two phases is postulated, similar to that in a dilute Stokes flow. Consequently, the numerical solutions relax the restriction of elastic inter-particle collisions and show good agreement with experimental measurements. In the above two regimes, the kinetic theory of dry granular flow is adopted for the particulate stresses because the inter-particle collisions dominate the flows. The interstitial gas influence on the constitutive flow behaviour of the particulate phase is considered in the relatively dilute flow regime also, and a k-equation with a prescribed turbulent length scale is first used to address the gas turbulence modulation. Numerical results show that the gas turbulence has a significant effect on the microscopic flow behaviour of the particulate phase. The k-equation of Crowe & Gillandt (1998) has the best performance in predicting the experimentally observed phenomena. Finally, the influence of the particles on the k-Ε model coefficients are studied and the turbulent motion is considered to be restricted by the particles, thereby reducing the turbulent length scale directly. The simulation results indicate that these coefficients should be modified in order to incorporate the effect of particles.
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Calabretta, Jacob S. "A Three Dimensional Vortex Particle-Panel Code For Modeling Propeller-Airframe Interaction." DigitalCommons@CalPoly, 2010. https://digitalcommons.calpoly.edu/theses/336.
Повний текст джерелаАнотація:
Analysis of the aerodynamic effects of a propeller flowfield on bodies downstream of the propeller is a complex task. These interaction effects can have serious repercussions for many aspects of the vehicle, including drag changes resulting in larger power requirements, stability changes resulting in adjustments to stabilizer sizing, and lift changes requiring wing planform adjustments.
Historically it has been difficult to accurately account for these effects at any stage during the design process. More recently methods using Euler solvers have been developed that capture interference effects well, although they don't provide an ideal tool for early stages of aircraft design, due to computational cost and the time and expense of setting up complex volume grids. This research proposes a method to fill the void of an interference model useful to the aircraft conceptual and preliminary designer.
The proposed method combines a flexible and adaptable tool already familiar to the conceptual designer in the aerodynamic panel code, with a pseudo-steady slipstream model wherein rotational effects are discretized onto vortex particle point elements. The method maintains a freedom from volume grids that are so often necessary in the existing interference models. In addition to the lack of a volume grid, the relative computational simplicity allows the aircraft designer the freedom to rapidly test radically different configurations, including more unconventional designs like the channel wing, thereby providing a much broader design space than otherwise possible.
Throughout the course of the research, verification and validation studies were conducted to ensure the most accurate model possible was being applied. Once the vortex particle scheme had been verified, and the ability to model an actuator disk with vortex particles had been validated, the overall product was compared against propeller-wing wind tunnel results conducted specifically as benchmarks for numerical methods.
The method discussed in this work provides a glimpse into the possibility of pseudo-steady interference modeling using vortex particles. A great groundwork has been laid that already provides reasonable results, and many areas of interest have been discovered where future work could improve the method further. The current state of the method is demonstrated through simulations of several configurations including a wing and nacelle and a channel wing.
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Crowe, Adam. "Inclined Negatively Buoyant Jets and Boundary Interaction." Thesis, University of Canterbury. Civil and Natural Resources Engineering, 2013. http://hdl.handle.net/10092/7895.
Повний текст джерелаАнотація:
Inclined negatively buoyant jets are commonly used to dispose brine effluent produced by desalination plants. Desalination and associated research has expanded in recent years due to the continued depletion and degradation of natural potable water sources. Desalination plants are the preferred option for meeting water demand deficits in many countries around the world. Inclined negatively buoyant jets are produced when the brine is discharged at an upward inclined angle via an offshore pipeline and diffuser system. Previous experimental studies have focused on the rapid mixing and dilution achieved by these discharges, as well as geometric parameters. Dilution measurements between these experimental studies vary significantly, which is possibly due to variations in the location of a lower boundary on observed flow behaviour. In the present study, velocity field information is experimentally measured for inclined negatively buoyant jets and compared to integral model predictions. Experiments are conducted with and without a lower boundary influencing observed flow behaviour, thus allowing the effects of a lower boundary to be determined.
The particle tracking velocimetry experimental technique is employed to measure near field velocities of these discharges. Firstly, discharges with source angles between 15\degree and 75\degree are investigated without boundary influence in stationary ambient conditions. The source was a minimum of 655 mm above the bottom of the experimental tank to ensure there was no lower boundary influence on observed behaviour. Time-averaged and fluctuating data are extracted along the trajectory of discharges. All non-dimensionalised geometric and centreline velocity parameters are found to collapse. Empirical coefficients are compared to previous experimental studies and integral model predictions.
A new detrainment model is developed to predict the behaviour of inclined negatively buoyant jets without boundary influence. The model further develops recent attempts to allow for buoyancy flux reduction along the flow path. The reduction in buoyancy flux is dependent on the local parameters of the flow and simulates experimentally observed detrainment. Dilution, geometric, and velocity predictions are found to be improved over previous models when compared to experimental data.
Finally, a raised platform was placed inside the experimental tank to determine the influence of a lower boundary on inclined negatively buoyant jets. Source angles of 30\degree, 45\degree, and 60\degree are investigated at three different non-dimensional source heights. The lower boundary is horizontal and ambient conditions are again stationary. Discharges impinge the lower boundary before forming a radially spreading layer along the boundary. Geometric and velocity data are compared to the first set of experiments in this study to determine the influence of the lower boundary on observed flow behaviour. Empirical coefficients at maximum height are similar with and without the influence of the boundary, whereas coefficients are substantially influenced at the return point when the boundary is present.
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Van, Wyk Geritza. "Simulation of tribological interactions in bonded particle-solid contacts." Thesis, Stellenbosch : Stellenbosch University, 2012. http://hdl.handle.net/10019.1/71941.
Повний текст джерелаАнотація:
Thesis (MScEng)--Stellenbosch University, 2012.ENGLISH ABSTRACT: In this study, tool forces from rock cutting tests were numerically simulated through a discrete element method (DEM) in association with PFC3D™. Tribological interactions such as contact, shearing, fracturing, friction and wear were presented during these cutting simulations. Particle assemblies, representing Paarl granite and Sandstone-2, were created in PFC3D™ through a material-genesis procedure. The macro-properties of these particle assemblies, namely Young’s modulus, Poisson’s ratio, uniaxial and triaxial compressive strength and Brazilian tensile strength, were calibrated by modelling the uniaxial and triaxial compressive strength test and the Brazilian tensile strength test. The calibration was done through adjustment of the micro-properties of the assembly, namely the stiffness and strength parameters of the particles and bonds. The influence of particle size on the calibration was also investigated. These assemblies were used in the rock cutting tests. Results suggested that DEM can reproduce the damage formation during calibration tests successfully. From the results obtained from the calibration tests, it was also concluded that particle size is not a free parameter but influences the macro-properties greatly. Different rock cutting tools were simulated, namely point-attack (conical) picks, chisel-shaped tools and button-shaped tools. The numerical cutting tools were treated as rigid walls to simplify the simulation and the tool forces were not influenced by wear. In each simulation the cutting tools advanced at a constant velocity. The tool forces acting on the cutting tool, in three orthogonal directions, were recorded during the numerical simulations and the peak cutting forces were predicted by theoretical equations. The damage to the Paarl granite and Sandstone-2 assemblies was revealed as broken bonds, which merge into microscopic fractures. The mean peak cutting forces of sharp cutting tools obtained from numerical, theoretical and experimental models (from the literature) were compared. Finally the influence of factors, including wear on the tool and depth of cut, on the value of tool forces was also investigated. The results from the rock cutting tests revealed that the correlation between the numerical and the experimental models as well as the theoretical and experimental models was not strong when using sharp point-attack and chisel-shaped picks. It was concluded that the influence of wear plays a substantial part in the cutting process and it has to be included during the numerical simulation for the results to be accurate and verifiable. This study also found that there is a non-linear increase in tool forces with an increase in depth of cut, since the contact area increases. At larger cutting depths, chip formation also generally increased and therefore damage to the sample as well as wear on the cutting tool will be minimized at shallow cutting depths. Overall this study concludes that DEM are capable of simulating calibration methods and rock cutting processes with different cutting tools and producing results which are verifiable with experimental data. Therefore numerical prediction of tool forces will allow the design of efficient cutting systems and the operational parameters as well as the performance prediction of excavation machines.
AFRIKAANSE OPSOMMING: In hierdie studie is die kragte wat tydens rotssny-toetse op die sny gereedskap inwerk, numeries gesimuleer met behulp van ‘n diskrete element metode (DEM) in samewerking met PFC3D™. Tribologiese interaksies soos kontak, skeer, breking, wrywing en slytasie is gedurende hiersie snytoetse voorgestel. Partikel versamelings, wat Paarl graniet en Sandsteen-2 verteenwoordig, is in PFC3D™ geskep deur middel van ‘n materiaal-skeppings prosedure. Die makro-eienskappe van die partikel versamelings, naamlik Young se modulus, Poisson se verhouding, eenassige en drie-assige druksterkte en Brasiliaanse treksterkte, is gekalibreer deur modellering van die eenassige en drie-assige druksterkte toets en die Brasiliaanse treksterkte toets. Die kalibrasie is gedoen deur aanpassing van die mikro-eienskappe, naamlik die styfheid en die sterkte parameters van die partikels en bindings. Die invloed van partikelgrootte is ook ondersoek. Daarna is hierdie versamelings in die rotssny-toetse gebruik. Resultate het daarop gedui dat DEM die kraakvorming gedurende kalibrasie toetse suksesvol kan reproduseer. Vanuit die kalibrasie is ook gevind dat die partikelgrootte nie ‘n vrye parameter is nie, maar die makro-eienskappe grotendeels beïnvloed. Verskillende rotssny gereedskap is gesimuleer, naamlik koniese, beitel-vormige en knopie-vormige instrumente. Die numeriese sny gereedskap is gesimuleer as rigiede mure om simulasies te vereenvoudig en die gereedskap-kragte is dus nie deur slytasie beïnvloed nie. Tydens elke simulasie is die sny gereedskap vorentoe beweeg teen ‘n konstante snelheid. Die gereedskap-kragte, in drie ortogonale rigtings, is aangeteken gedurende die numeriese simulasies en die piek snykragte is ook voorspel deur teoretiese vergelykings. Die skade aan die Paarl graniet en Sandsteen-2 versamelings, is voorgestel as gebreekte bindings, wat saamsmelt tot mikroskopiese frakture. Die gemiddelde piek snykragte van skerp sny gereedskap van numeriese, teoretiese en eksperimentele modelle (uit die literatuur) is vergelyk. Ten slotte is die invloed wat faktore, onder andere die slytasie van gereedskap en die snydiepte, op die grootte van die kragte het ondersoek. Die resultate van die rotssny-toetse het aan die lig gebring dat die korrelasie tussen die numeriese en eksperimentale modelle sowel as die teoretiese en eksperimentele modelle nie sterk is tydens die gebruik van skerp koniese en beitel-vormige instrumente nie. Die gevolgtrekking is gemaak dat die invloed van slytasie van sny gereedskap ‘n wesenlike rol speel in die snyproses en dat dit in die numeriese simulasie ingesluit moet word sodat die resultate akkuraat en virifieerbaar is. Hierdie studie het ook gevind dat daar ‘n nie-lineêre toename in die gereedskap-kragte is met ‘n toename in snydiepte aangesien die kontak-area toeneem met ‘n toename in die snydiepte. By groter snydieptes, het die formasie van afsplinterings verhoog en dus sal skade aan die partikel versamelings en die slytasie van die gereedskap geminimeer word by vlakker snydieptes. Algeheel het die studie tot die gevolgtrekking gekom dat DEM in staat is om kalibrasie metodes en rotssny-toetse met verskillende sny gereedskap te simuleer asook om resultate te produseer wat verifieerbaar is met eksperimentele data. Numeriese voorspellings van die gereedskap-kragte sal dus toelaat om doeltreffende sny prosesse en operasionele parameters te ontwerp sowel as om die werkverrigting van uitgrawings masjiene te voorspel.
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Olsson, Helena. "Particle interactions and internal tablet structure : factors affecting the mechanical strength of pharmaceutical compacts /." Uppsala, Sweden : Uppsala University : Distributed by Uppsala University Library, 2000. http://w3.ub.uu.se/diss/eng/abstract.cfm?ISBN=91-554-4725-2.
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Pinate, Santiago. "Study of particle-current-electrocrystallization interactions in electroplating of Ni/SiC coatings." Licentiate thesis, Tekniska Högskolan, Högskolan i Jönköping, JTH, Material och tillverkning, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:hj:diva-43548.
Повний текст джерелаАнотація:
Composite coatings have great potential due to the possibility to combine properties of two different materials in one coating. This way, new surface properties can be tailored and applied to any material's surface. Among different manufacturing routes, electrodeposition has the biggest potential in creating composite metal matrix coatings, especially nanocomposites. Nevertheless, there is a knowledge gap between the deposition of composite coatings in laboratory conditions, described in the literature, and those that are now in place on an industrial level. While micro-composites have been industrialised for about ten years, the production of Ni/SiC nanocomposite coatings by electroplating is still far from an industrial manufacturing floor. This is due to the lack of understanding of the mechanisms of nanoparticles codeposition leading to scattering results. The production of nanocomposite coatings is much more sensitive to the process parameters compared to microcomposite. The correlation between parameters and their influence on the codeposition are still not fully identified and understood. The codeposition models proposed in the literature are only valid in specific conditions, but composite depositions behave differently, or even opposite if some of the variables are modified. The main objective of this work is to identify the particle-current-electrocrystallization interactions in the production of Ni/SiC nanocomposites. A series of experiments are designed to isolate single variables and identify the controlling parameters of these interactions and their impact on the final properties. In this thesis, the effect of current density, type of current and particles size are identified as primary variables controlling the metal crystallisation and coatings properties. Among many parameters, a specific current waveform in pulse reverse mode proved to increase the codeposition rate effectively, doubling the content of nanoparticles compared to other techniques. Ultrasound assistance is also considered as stirring method when particles are suspended in the deposition bath to increase their stability and dispersion. The effect of Ultrasound on the particles codeposition and metal crystallisation is studied and compared to silent condition. Moreover, a surface treatment for the particle has been proven successful in making any particle to behave similarly in the Ni deposition bath. Furthermore, the codeposition rate doubled or tripled compared to untreated ones thanks to this treatment. Both ultrasonic agitation and surface treatment reduce the formation of aggregates, improving the particle dispersion and metal microstructure thus increasing the final hardness. The work proved the synergistic effect between particle and metal microstructure which affected the final properties of the coating. Therefore, when tailoring the composite coating to improve hardness, it is not only the amount of the particles that should be considered but also their influence on the electrocrystallisation process.Kompositbeläggning har stort potential tack vare möjligheten att kombinera två material i samma ytskikt. På detta sätt kan nya ytegenskaper skräddarsys och appliceras på ett materials yta. Elektrodeposition är den tillverkningsmetod som har störst potential att uppnå kompositbeläggningar, i synnerhet nanokompositer. Ett kunskapsgap existerar mellan elektrodeposition under laboratorieförhållanden, som beskrivet i vetenskaplig litteratur, och hur processen går till i industriell miljö. Medan industriell tillämpning av mikrokompositer pågått ungefär tio år, så har produktion av Ni/SiC nanokompositbeläggningar fortfarande inte nått fabriksgolvet. Detta är en konsekvens av bristande förståelse kring mekanismer för samdeposition av nanopartiklar som leder till varierande resultat. Produktion av nanokompositbeläggningar är mycket mer känslig för processparametrar jämfört med mikrokompositer. Korrelationer mellan parametrar och dess inverkan på samdeposition är fortfarande inte fullt identifierade och förstådda. Modeller för samdeposition som föreslås i vetenskaplig litteratur är endast giltiga under särskilda förhållanden. Kompositdeposition kan uppvisa avvikande eller till och med motsatt beteende om variabler förändras. Huvudmålet med detta arbete är att identifiera interaktioner mellan partikel, ström och elektrokristallisering under tillverkning av Ni/SiC nanokompositer. En serie av experiment är utvecklade för att isolera variabler och identifiera de parametrarna som kontrollerar dessa interaktioner och dess inverkan på ytans egenskaper. I denna avhandling identifieras strömtäthet, typ av ström, och partiklars storlek som primära variabler som kontrollerar metallkristallisering och beläggningens egenskaper. Bland många parametrar, visades en specifik vågform på strömmen i omvänd pulsläge öka samdepositionen effektivt, ledande till en fördubbling av andelen nanopartiklar jämfört med andra tekniker. Ultraljud tillämpades som metod för omrörning av depositionsbadet för förbättrad stabilitet och fördelning. Effekten av ultraljud på samdepositionen av metallkristallisering studeras och jämfört med tyst tillstånd. Dessutom har en ytbehandling för partiklarna visats framgångsrik för att få godtyckliga partiklar att bete sig likt Ni i depositionsbadet. Detta ledde till att samdepositionens takt ökade med en faktor av två till tre jämfört med obehandlade partiklar. Både ultraljud och ytbehandling av partiklarna ledde till minskad aggregation vilket förbättrade fördelningen av partiklar och metallstruktur och därigenom ökad hårdhet. Arbetet bevisar synergieffekten mellan partiklar och metallstruktur vilket påverkar beläggningens slutliga egenskaper. Vid utveckling av nya ytbeläggningar ska därför inte bara mängden partiklar beaktas utan även dess interaktion med elektrokristalliseringsprocessen.
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Reynolds, Scott B. "Particle Image Velocimetry Analysis on the Effects of Stator Loading on Transonic Blade-Row Interactions." Diss., CLICK HERE for online access, 2010. http://contentdm.lib.byu.edu/ETD/image/etd3423.pdf.
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Lin, Yuan. "Numerical modeling of dielectrophoresis." Licentiate thesis, Stockholm, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4014.
Повний текст джерелаКниги з теми "Partial interaction mechanics"
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Jürgen, Tomas, and SpringerLink (Online service), eds. Micro-Macro-interaction: In Structured media and Particle Systems. Berlin, Heidelberg: Springer Berlin Heidelberg, 2008.
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R, Baier, and Wegener D, eds. Proceedings of the XXth International Symposium on Multiparticle Dynamics, Gut Holmecke near Dortmund, Germany 10-14 September, 1990. Singapore: World Scientific, 1991.
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1975-, Sims Robert, and Ueltschi Daniel 1969-, eds. Entropy and the quantum II: Arizona School of Analysis with Applications, March 15-19, 2010, University of Arizona. Providence, R.I: American Mathematical Society, 2011.
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Herrmann, Samuel. Stochastic resonance: A mathematical approach in the small noise limit. Providence, Rhode Island: American Mathematical Society, 2014.
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Layton, Anita T., and Sarah D. Olson. Biological fluid dynamics: Modeling, computations, and applications : AMS Special Session, Biological Fluid Dynamics : Modeling, Computations, and Applications : October 13, 2012, Tulane University, New Orleans, Louisiana. Providence, Rhode Island: American Mathematical Society, 2014.
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Howes, Andrew, Xiuli Chen, Aditya Acharya, and Richard L. Lewis. Interaction as an Emergent Property of a Partially Observable Markov Decision Process. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198799603.003.0011.
Повний текст джерелаАнотація:
In this chapter we explore the potential advantages of modeling the interaction between a human and a computer as a consequence of a Partially Observable Markov Decision Process (POMDP) that models human cognition. POMDPs can be used to model human perceptual mechanisms, such as human vision, as partial (uncertain) observers of a hidden state are possible. In general, POMDPs permit a rigorous definition of interaction as the outcome of a reward maximizing stochastic sequential decision processes. They have been shown to explain interaction between a human and an environment in a range of scenarios, including visual search, interactive search and sense-making. The chapter uses these scenarios to illustrate the explanatory power of POMDPs in HCI. It also shows that POMDPs embrace the embodied, ecological and adaptive nature of human interaction.
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Bertram, Albrecht, and Jürgen Tomas. Micro-Macro-Interactions: In Structured Media and Particle Systems. Springer, 2010.
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Fields & Fundamental Interactions. Gordon & Breach Publishing Group, 2001.
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Furst, Eric M., and Todd M. Squires. Particle motion. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780199655205.003.0002.
Повний текст джерелаАнотація:
The movement of colloidal particles in simple and complex fluids and viscoelastic solids is central to the microrheology endeavor. All microrheology experiments measure the resistance of a probe particle forced to move within a material, whether that probe is forced externally or simply allowed to fluctuate thermally. This chapter lays a foundation of the fundamental mechanics of micrometer-dimension particles in fluids and soft solids. In an active microrheology experiment, a colloid of radius a is driven externally with a specifed force F (e.g.magnetic, optical, or gravitational), and moves with a velocity V that is measured. Of particular importance is the role of the Correspondence Principle, but other key concepts, including mobility and resistance, hydrodynamic interactions, and both fluid and particle inertia, are discussed. In passive microrheology experiments, on the other hand, the position of a thermally-uctuating probe is tracked and analyzed to determine its diffusivity.
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Aitchison, I. J. R., and A. J. G. Hey. Gauge Theories in Particle Physics, Volume I: From Relativistic Quantum Mechanics to QED (Graduate Student Series in Physics). 3rd ed. Taylor & Francis, 2002.
Знайти повний текст джерелаЧастини книг з теми "Partial interaction mechanics"
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Löwe, Jens-Michael, Michael Kempf, and Volker Hinrichsen. "Mechanical and Electrical Phenomena of Droplets Under the Influence of High Electric Fields." In Fluid Mechanics and Its Applications, 355–72. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-031-09008-0_18.
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AbstractHigh-voltage composite insulators are specially designed to withstand different environmental conditions to ensure a reliable and efficient electric power distribution and transmission. Especially, outdoor insulators are exposed to rain, snow or ice, which might significantly affect the performance of the insulators. The interaction of sessile water droplets and electric fields is investigated under various boundary conditions. Besides the general behavior of sessile droplets, namely the deformation and oscillation, the inception field strength for partial discharges is examined depending on the droplet volume, strength and frequency of the electric field and the electric charge. Particularly, the electric charge is identified to significantly affect the droplet behavior as well as the partial discharge inception field strength. In addition to ambient conditions, the impact of electric fields on ice nucleation is investigated under well-defined conditions with respect to the temperature and electric field strength. High electric field strengths are identified to significantly promote ice nucleation, especially in case of alternating and transient electric fields. Different influencing factors like the strengths, frequencies and time constants of the electric fields are investigated. Consequently, the performed experiments enhance the knowledge of the behavior of water droplets under the impact of electric fields under various conditions.
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Phillies, George D. J. "Interacting Particle Effects." In Elementary Lectures in Statistical Mechanics, 401–12. New York, NY: Springer New York, 2000. http://dx.doi.org/10.1007/978-1-4612-1264-5_36.
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Thornton, Colin, and Guoping Lian. "Energy Considerations During Oblique Particle Interactions." In Contact Mechanics, 381–88. Boston, MA: Springer US, 1995. http://dx.doi.org/10.1007/978-1-4615-1983-6_52.
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Brandt, Siegmund, Hans Dieter Dahmen, and Tilo Stroh. "Free Particle Motion in One Dimension." In Interactive Quantum Mechanics, 5–31. New York, NY: Springer New York, 2010. http://dx.doi.org/10.1007/978-1-4419-7424-2_2.
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Brandt, Siegmund, Hans Dieter Dahmen, and Tilo Stroh. "Free Particle Motion in Three Dimensions." In Interactive Quantum Mechanics, 138–57. New York, NY: Springer New York, 2010. http://dx.doi.org/10.1007/978-1-4419-7424-2_6.
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Brandt, Siegmund, Hans Dieter Dahmen, and Tilo Stroh. "Free Particle Motion in One Dimension." In Interactive Quantum Mechanics, 5–23. New York, NY: Springer New York, 2003. http://dx.doi.org/10.1007/978-0-387-21653-9_2.
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Brandt, Siegmund, Hans Dieter Dahmen, and Tilo Stroh. "Free Particle Motion in Three Dimensions." In Interactive Quantum Mechanics, 107–25. New York, NY: Springer New York, 2003. http://dx.doi.org/10.1007/978-0-387-21653-9_6.
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Crowe, C. T., T. R. Troutt, and J. N. Chung. "Particle Interactions with Vortices." In Fluid Mechanics and Its Applications, 829–61. Dordrecht: Springer Netherlands, 1995. http://dx.doi.org/10.1007/978-94-011-0249-0_19.
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Brandt, Siegmund, Hans Dieter Dahmen, and Tilo Stroh. "A Two-Particle System: Coupled Harmonic Oscillators." In Interactive Quantum Mechanics, 122–37. New York, NY: Springer New York, 2010. http://dx.doi.org/10.1007/978-1-4419-7424-2_5.
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Brandt, Siegmund, Hans Dieter Dahmen, and Tilo Stroh. "A Two-Particle System: Coupled Harmonic Oscillators." In Interactive Quantum Mechanics, 91–106. New York, NY: Springer New York, 2003. http://dx.doi.org/10.1007/978-0-387-21653-9_5.
Повний текст джерелаТези доповідей конференцій з теми "Partial interaction mechanics"
1
Edd, Shannon N., Nathan A. Netravali, Nicholas J. Giori, and Thomas P. Andriacchi. "Effect of Partial Medial Meniscectomy on the Interaction Between Primary and Secondary Knee Motion During Gait." In ASME 2012 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/sbc2012-80399.
Повний текст джерелаАнотація:
Meniscal injury is a well-known risk factor for osteoarthritis (OA); the leading treatment (meniscectomy) increases the risk for osteoarthritis four times over sixteen years [1]. Reports that meniscectomy patients display altered gait kinetics and kinematics post-operation [2,3] suggest altered gait mechanics as a potential link between meniscal resection and increased risk for OA. Specifically it has been suggested that altered gait is a pathway to OA by causing a shift in tibiofemoral cartilage contact location to unprepared regions, which leads to cartilage breakdown [4]. The altered gait mechanics of particular interest are secondary motions of the knee, including internal-external (IE) rotation and adduction angle. While previous research has shown there to be a decrease in early stance (ES) and mid-stance (MS) range of motion (ROM) in knee flexion angle along with decreased peak extension of the affected versus contralateral limb, there is a lack of data relating the interaction between primary (flexion) and secondary (IE rotation and adduction angle) motions of the knee in the meniscectomy population [2,3]. Yet this information is important for understanding the ambulatory conditions associated with knee OA following meniscectomy.
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Olunloyo, Vincent O. S., Charles A. Osheku, and Adekunle O. Adelaja. "On the Mechanics of Pipewalking: Case of a Buried Pipeline." In ASME 2010 29th International Conference on Ocean, Offshore and Arctic Engineering. ASMEDC, 2010. http://dx.doi.org/10.1115/omae2010-20094.
Повний текст джерелаАнотація:
The influence of soil sedimentation on the pipe walking phenomenon is investigated analytically via a set of coupled nonlinear partial differential equations where the effects of operating variables such as internal fluid temperature variation, prestress and internal pressurization, Coriolis and axial accelerations of the internal fluid and cross sectional area change are fully captured. For this problem, a segment of an offshore pipeline resting on the ocean floor is idealized as elastic beam on an elastic foundation using recently refined Euler-Bernoulli beam theory. By invoking integral transforms, closed form analytical expressions for displacement of the fluid-pipe-soil interaction system associated with pipe walking is computed. Simulated results showed that pipe walking phenomenon is strongly dependent on sedimentation level, friction at the interface of pipe-ocean sub soil layer, temperature variation, fluctuations in internal fluid pressurisation and oscillatory strain of the pipe in both transverse and longitudinal modes.
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Videiro, Paulo Mauricio, Luis Volnei Sudati Sagrilo, and Edison Castro Prates de Lima. "A LRFD Code Format for Accounting Long-Term Variation of Multiple Load Effects." In ASME 2002 21st International Conference on Offshore Mechanics and Arctic Engineering. ASMEDC, 2002. http://dx.doi.org/10.1115/omae2002-28032.
Повний текст джерелаАнотація:
This paper proposes a Load and Resistance Factors Design (LRFD) code format for structural components of offshore structures under multiple load effects. This code format accounts for the long-term variation of seastate and the actual correlation between dynamic load effects due to environmental actions. Ultimate limit states are formulated in terms of an Interaction Ratio (IR) random variable, such that the long-term extreme value of IR greater than unity means component failure. The long-term distribution of IR is obtained by combining the distribution of each short-term seastate. The short-term response of the generally nonlinear IR is determined by time domain simulation, taking into account partial load and resistance factors. The IR short-term distribution may be fitted, for instance, by using Rayleigh or Weibull distribution. The main advantages of the proposed code format are: • This code format accounts implicitly and correctly for the actual correlation among all dynamic environmental load processes. • Structural designers have used interaction ratios for a long time. Hence, it is straightforward to evolve from a deterministic stage of looking for IR < 1, as in old Working Stress Design codes, to a code format where the aim is to design structural components with long term IR extreme value < 1. The feasibility of the proposed code format is demonstrated by calibrating partial factors for beam-column cylindrical members based on components of a Floating Production System Semi-submersible hull.
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Gupta, Himanshu, Robert Blevins, and Hugh Banon. "Effect of Moonpool Hydrodynamics on Spar Heave." In ASME 2008 27th International Conference on Offshore Mechanics and Arctic Engineering. ASMEDC, 2008. http://dx.doi.org/10.1115/omae2008-57264.
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A Spar is a deep draft platform for oil and gas production and drilling operations. One of the features of the Spar platform is the presence of a moonpool (or centerwell) inside the cylindrical hull structure. A unique aspect of the moonpool in Spars is the presence of partial closure plates at the bottom. The seawater goes in and out of the moonpool though these bottom closure (or guide) plates. Depending on the design of a Spar (e.g., the number of risers), typical period of moonpool vertical oscillation can be close to the peak of extreme seastate spectra. The Spar heave motion is thus coupled with the moonpool water oscillation and presents itself as a two oscillator problem. The complex behavior of moonpool and Spar heave interaction is largely ignored in current practice, via conservative assumptions (this is also due to lack of a mathematical model). A new model describing this interaction between moonpool water oscillation and the Spar heave has been developed in this paper. The results of the new model highlight the importance of the moonpool hydrodynamics in predicting the heave motions of Spars.
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Song, Hao, and Longbin Tao. "Scaled Boundary FEM Solution of Wave Diffraction by a Circular Cylinder." In ASME 2007 26th International Conference on Offshore Mechanics and Arctic Engineering. ASMEDC, 2007. http://dx.doi.org/10.1115/omae2007-29223.
Повний текст джерелаАнотація:
The scaled boundary finite-element method (SBFEM) is a novel semi-analytical approach, with the combined advantages of both finite-element and boundary-element methods. The basic idea behind SBFEM is to discretize the surface boundary by FEM and transform the governing partial differential equations to ordinary differential equations of the radial parameter. The radial differential equation is then solved analytically. It has the inherent advantage for solving problems in unbounded medium with discretization to the interface only. In this paper, SBFEM is applied to solve the wave diffraction by a circular cylinder. The final radial matrix differential equation is solved fully analytically without adoption of any numerical scheme. Comparisons to the previous analytical solutions demonstrate the excellent computation accuracy and efficiency of the present SBFEM approach. It also revealed the great potential of the SBFEM to solve more complex wave-structure interaction problems.
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Olunloyo, Vincent O. S., Charles A. Osheku, and Sidikat I. Kuye. "On the Dynamics and Stability of a Viscoelastic Pipe Conveying a Non-Newtonian Fluid." In ASME 2009 28th International Conference on Ocean, Offshore and Arctic Engineering. ASMEDC, 2009. http://dx.doi.org/10.1115/omae2009-79588.
Повний текст джерелаАнотація:
Flow induced vibration of pipeline and riser systems are strongly dependent on internal fluid flow parameters as well as the mechanical properties of the conveyance vessel. The effect of variability of flow parameters especially at elevated temperatures can lead to instability, buckling and bursting of these systems. In this paper, the effect of high temperature fluid transmission on the vibration and stability of an offshore viscoelastic pipeline conveying a non-Newtonian fluid is investigated analytically. By idealising the viscoelastic pipeline resting on the sea bed as a viscoelastic beam that is resting on an elastic continuum, a non-linear boundary value partial differential equation governing the fluid-structure-soil interaction mechanics is formulated. In particular, formal linearization of the governing partial differential equation, under slight perturbation of the internal fluid velocity and other flow variables revealed their impact, on the natural frequency and stability of the system which can then be computed for design analysis and applications.
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Olunloyo, Vincent O. S., Charles A. Osheku, and Olatunde Damisa. "On the Dynamics and Application of Sandwich Hydroelastic Foundation for Offshore Structures and Systems." In ASME 2009 28th International Conference on Ocean, Offshore and Arctic Engineering. ASMEDC, 2009. http://dx.doi.org/10.1115/omae2009-79565.
Повний текст джерелаАнотація:
Subsea systems and structures are constantly being redesigned, reshaped and reconstructed to enhance offshore exploration, production and exploitation activities. Their structural stability and integrity are strongly dependent on the ability of their foundation footings to dissipate vibration energy arising from external influences such as hydrodynamic forces and propagation of seismic waves through a moving seabed or ocean floor. In this paper, the dynamic behavior, suitability and application of sandwich hydroelastic foundation system for vibration control and enhancement of structural stability in subsea structures is investigated analytically. By employing mechanics of contact and laminated thin plate theory, a well posed boundary value partial differential equation is formulated for a fluid-structure-soil interaction model of slip damping mechanism. For this problem, the proposed sandwich foundation footing is assumed to be partially buried on a moving seabed and is idealized as two sandwich homogenous hydroelastic plate layers in a moving elastic subsoil layer. By assuming linear pressure profiles across the plate axes, the effects of varying pressure gradients and subsoil layer sliding velocities, across the foundation axes, on the energy dissipation mechanism are computed for design analysis and applications.
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Goplen, Stig, Pa˚l Stro̸m, Erik Levold, and Kim J. Mo̸rk. "HotPipe JIP: HP/HT Buried Pipelines." In ASME 2005 24th International Conference on Offshore Mechanics and Arctic Engineering. ASMEDC, 2005. http://dx.doi.org/10.1115/omae2005-67524.
Повний текст джерелаАнотація:
The HotPipe Project is a Joint Industry Project, whose overall objective is to prepare a DNV Recommended Practice to be used in structural design of high temperature/high pressure pipelines. The developed design criteria are based on the application of structural reliability methods to calibrate the partial safety factors involved. One of the three scenarios covered in this DNV-RP is buried pipes subjected to upheaval buckling which is discussed in this paper. The most significant factor in this scenario is uncertainty in the pipeline configuration and uncertainty in the pipe-soil interaction. The paper presents the background of the proposed soil capacities and the associated uncertainties for both uplift resistance and downward resistance in cohesive and non-cohesive soil. The paper links these soil models with the design requirements to upheaval buckling including: - Functional requirements i.e. survey data accuracy, smoothing of survey data, modeling of the pipeline, design conditions, soil cover etc.; - Trenching technology; - Qualification of the minimum soil cover, natural or artificial, with the aim to guarantee pipeline stability; - Assessment of pipeline response; - Pipe integrity checks and design criteria. The internal confidential project guideline has been completed and is currently in the process of being converted into an official DNV-RP-F110, to be published later this year.
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Vitali, Luigino, Enrico Torselletti, Maurizio Spinazze`, Roberto Bruschi, and Luca Brunetto. "Bending Capacity of Pipes Subject to Point Loads." In ASME 2003 22nd International Conference on Offshore Mechanics and Arctic Engineering. ASMEDC, 2003. http://dx.doi.org/10.1115/omae2003-37222.
Повний текст джерелаАнотація:
Large bending moments may develop on free pipeline lengths in the proximity of pipe sections subject to a local force. Sometimes the local force is such as to cause a partial loss of the sectional strength capacity of the pipe. This is the case of a pipeline plastically bent over the stinger of an S-lay barge, or of a pipeline laid on the sea bottom and hooked by an anchor or trawling gear, or of a pipe subject to cold bending when it is made to cope with sharp bottom roughness etc. In such conditions, the limit bending capacity of the pipe section, subject to local load effects, is significantly influenced. This aspect is not covered by international design codes and the scope of this paper is to show that, in some circumstances, it must be taken into due account. In this paper: • The relevant literature as concerns experimental tests, interpretative models, analysis methodologies and design approaches, is reviewed; • The FE model and post-processing, purpose-developed to investigate the interaction between local and global effect, are discussed; • The findings of FE analyses, in particular the effect of load combination, load history, pipe geometric characteristics and loading — magnitude and shape of the contact area, are presented. It is concluded that the limit bending capacity reduces significantly when local effects are such as to develop stresses on the pipe wall that affect the activation of the sectional buckling mechanism.
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Bertaglia, Giulia. "Augmented fluid-structure interaction systems for viscoelastic pipelines and blood vessels." In VI ECCOMAS Young Investigators Conference. València: Editorial Universitat Politècnica de València, 2021. http://dx.doi.org/10.4995/yic2021.2021.13450.
Повний текст джерелаАнотація:
Mathematical models and numerical methods are a powerful resource for better understanding phenomena and processes throughout the fluid dynamics field, allowing significant reductions in the costs, which would otherwise be required to perform laboratory experiments, and even allowing to obtain useful data that could not be gathered through measurements.The correct characterization of the interactions that occur between the fluid and the wall that surrounds it is a fundamental aspect in all contexts involving deformable ducts, which requires the utmost attention at every stage of both the development of the computational method and the interpretation of the results and their application to cases of practical interest.In this work, innovative mathematical models able to predict the behavior of the fluid-structure interaction (FSI) mechanism that underlies the dynamics of flows in different compliant ducts is presented. Starting from the purely civil engineering sector, with the study of plastic water pipelines, the final application of the proposed tool is linked to the medical research field, to reproduce the mechanics of blood flow in both arteries and veins. With this aim, various linear viscoelastic models, from the simplest to the more sophisticated, have been applied and extended to obtain augmented FSI systems in which the constitutive equation of the material is directly embedded into the system as partial differential equation [1]. These systems are solved recurring to second-order Finite Volume Methods that take into account the recent evolution in the computational literature of hyperbolic balance laws systems [2]. To avoid the loss of accuracy in the stiff regimes of the proposed systems, asymptotic-preserving IMEX Runge-Kutta schemes are considered for the time discretization, which are able to maintain the consistency and the accuracy in the diffusive limit, without restrictions due to the scaling parameters [3]. The models have been extensively validated through different types of test cases, highlighting the advantages of using the augmented formulation of the system of equations. Furthermore, comparisons with experimental data have been considered both for the water pipelines scenario and the blood flow modeling, recurring to in-vivo measurements for the latter.REFERENCES[1] Bertaglia, G., Caleffi, V. and Valiani, A. Modeling blood flow in viscoelastic vessels: the 1D augmented fluid-structure interaction system. Comput. Methods Appl. Mech. Eng., 360(C):112772 (2020).[2] Bertaglia, G., Ioriatti, M., Valiani, A., Dumbser, M. and Caleffi, V. Numerical methods for hydraulic transients in visco-elastic pipes. J. Fluids Struct., 81:230-254 (2018).[3] Pareschi, L. and Russo, G. Implicit-explicit Runge-Kutta schemes and applications to hyperbolic systems with relaxation. J. Sci. Comput., 25:129-155 (2005).
Звіти організацій з теми "Partial interaction mechanics"
1
Brandl, Maria T., Shlomo Sela, Craig T. Parker, and Victor Rodov. Salmonella enterica Interactions with Fresh Produce. United States Department of Agriculture, September 2010. http://dx.doi.org/10.32747/2010.7592642.bard.
Повний текст джерелаАнотація:
The emergence of food-borne illness outbreaks linked to the contamination of fruits and vegetables is a great concern in industrialized countries. The current lack of control measures and effective sanitization methods prompt the need for new strategies to reduce contamination of produce. Our ability to assess the risk associated with produce contamination and to devise innovative control strategies depends on the identification of critical determinants that affect the growth and the persistence of human pathogens on plants. Salmonella enterica, a common causal agent of illness linked to produce, has the ability to colonize and persist on plants. Thus, our main objective was to identify plant-inducible genes that have a role in the growth and/or persistence of S. enterica on postharvest lettuce. Our findings suggest that in-vitro biofilm formation tests may provide a suitable model to predict the initial attachment of Salmonella to cut-romaine lettuce leaves and confirm that Salmonella could persist on lettuce during shelf-life storage. Importantly, we found that Salmonella association with lettuce increases its acid-tolerance, a trait which might be correlated with an enhanced ability of the pathogen to pass through the acidic barrier of the stomach. We have demonstrated that Salmonella can internalize leaves of iceberg lettuce through open stomata. We found for the first time that internalization is an active bacterial process mediated by chemotaxis and motility toward nutrient produced in the leaf by photosynthesis. These findings may provide a partial explanation for the failure of sanitizers to efficiently eradicate foodborne pathogens in leafy greens and may point to a novel mechanism utilized by foodborne and perhaps plant pathogens to colonize leaves. Using resolvase in vivo expression technology (RIVET) we have managed to identify multiple Salmonella genes, some of which with no assigned function, which are involved in attachment to and persistence of Salmonella on lettuce leaves. The precise function of these genes in Salmonella-leaf interactions is yet to be elucidated. Taken together, our findings have advanced the understanding of how Salmonella persist in the plant environment, as well as the potential consequences upon ingestion by human. The emerging knowledge opens new research directions which should ultimately be useful in developing new strategies and approaches to reduce leaf contamination and enhance the safety of fresh produce.
2
Chefetz, Benny, and Jon Chorover. Sorption and Mobility of Pharmaceutical Compounds in Soils Irrigated with Treated Wastewater. United States Department of Agriculture, 2006. http://dx.doi.org/10.32747/2006.7592117.bard.
Повний текст джерелаАнотація:
Research into the fate of pharmaceutical compounds (PCs) in the environment has focused on aspects of removal efficiency during sewage treatment, degradation in surface water and accumulation in soils and sediments. However, very little information is available on the binding interactions of pharmaceuticals with dissolved organic matter (DOM) originating from wastewater treatment. Such interactions can significantly affect the transport potential of PCs in soils by altering compound affinity for soil particle surfaces. Our primary hypothesis is that the transport potential of PCs in soils is strongly impacted by the type and strength of interaction with DOM and the stability of resulting DOM-PC complexes. The overarching goal of the proposed work is to develop a better understanding of the risk associated with introduction of PCs into the environment with treated wastewater. This goal has been achieved by elucidating the mechanisms of the interaction of selected pharmaceuticals (that have shown to be widespread wastewater contaminants) with DOM constituents; by determining the stability and fate of DOM-PC complexes introduced to soils and soil constituents; and by evaluating the potential uptake of these compounds by plants. Based on the results obtained in this study (column and batch sorption-desorption experiments), we suggest that PCs can be classified as slow-mobile compounds in SOM-rich soil layers. When these compounds pass this layer and/or are introduced into SOM-poor soils, their mobility increases significantly. Our data suggest that in semiarid soils (consisting of low SOM), PCs can potentially be transported to the groundwater in fields irrigated with reclaimed wastewater. Moreover, the higher mobility of the acid PCs (i.e., naproxen and diclofenac) in freshwater column systems suggests that their residues in soils irrigated with reclaimed wastewater can leach from the root zone and be transported to the groundwater after rain events. Our data obtained from the binding experiments of PCs with DOM demonstrate that the hydrophobic DOM fractions were more efficient at sorbing PCs than the more polar hydrophilic fractions at a pH near the pKa of the analytes. At the pH of natural semiarid water and soil systems, including that of reclaimed wastewater and biosolids, the role of the hydrophobic fractions as sorption domains is less important than the contribution of the hydrophilic fractions. We also hypothesize that the DOM fractions interact with each other at the molecular level and do not act as independent sorption domains. In summary, our data collected in the BARD project demonstrate that the sorption abilities of the DOM fractions can also significantly affect the mobility of pharmaceutical compounds in soils influenced by intensive irrigation with treated wastewater or amended with biosolids.
3
Chefetz, Benny, and Jon Chorover. Sorption and Mobility of Pharmaceutical Compounds in Soils Irrigated with Treated Wastewater. United States Department of Agriculture, 2006. http://dx.doi.org/10.32747/2006.7709883.bard.
Повний текст джерелаАнотація:
Research into the fate of pharmaceutical compounds (PCs) in the environment has focused on aspects of removal efficiency during sewage treatment, degradation in surface water and accumulation in soils and sediments. However, very little information is available on the binding interactions of pharmaceuticals with dissolved organic matter (DOM) originating from wastewater treatment. Such interactions can significantly affect the transport potential of PCs in soils by altering compound affinity for soil particle surfaces. Our primary hypothesis is that the transport potential of PCs in soils is strongly impacted by the type and strength of interaction with DOM and the stability of resulting DOM-PC complexes. The overarching goal of the proposed work is to develop a better understanding of the risk associated with introduction of PCs into the environment with treated wastewater. This goal has been achieved by elucidating the mechanisms of the interaction of selected pharmaceuticals (that have shown to be widespread wastewater contaminants) with DOM constituents; by determining the stability and fate of DOM-PC complexes introduced to soils and soil constituents; and by evaluating the potential uptake of these compounds by plants. Based on the results obtained in this study (column and batch sorption-desorption experiments), we suggest that PCs can be classified as slow-mobile compounds in SOM-rich soil layers. When these compounds pass this layer and/or are introduced into SOM-poor soils, their mobility increases significantly. Our data suggest that in semiarid soils (consisting of low SOM), PCs can potentially be transported to the groundwater in fields irrigated with reclaimed wastewater. Moreover, the higher mobility of the acid PCs (i.e., naproxen and diclofenac) in freshwater column systems suggests that their residues in soils irrigated with reclaimed wastewater can leach from the root zone and be transported to the groundwater after rain events. Our data obtained from the binding experiments of PCs with DOM demonstrate that the hydrophobic DOM fractions were more efficient at sorbing PCs than the more polar hydrophilic fractions at a pH near the pKa of the analytes. At the pH of natural semiarid water and soil systems, including that of reclaimed wastewater and biosolids, the role of the hydrophobic fractions as sorption domains is less important than the contribution of the hydrophilic fractions. We also hypothesize that the DOM fractions interact with each other at the molecular level and do not act as independent sorption domains. In summary, our data collected in the BARD project demonstrate that the sorption abilities of the DOM fractions can also significantly affect the mobility of pharmaceutical compounds in soils influenced by intensive irrigation with treated wastewater or amended with biosolids.
4
Manulis, Shulamit, Christine D. Smart, Isaac Barash, Guido Sessa, and Harvey C. Hoch. Molecular Interactions of Clavibacter michiganensis subsp. michiganensis with Tomato. United States Department of Agriculture, January 2011. http://dx.doi.org/10.32747/2011.7697113.bard.
Повний текст джерелаАнотація:
Clavibacter michiganensis subsp. michiganensis (Cmm), the causal agent of bacterial wilt and canker of tomato, is the most destructive bacterial disease of tomato causing substantial economic losses in Israel, the U.S.A. and worldwide. The molecular strategies that allow Cmm, a Gram-positive bacterium, to develop a successful infection in tomato plants are largely unknown. The goal of the project was to elucidate the molecular interactions between Cmmand tomato. The first objective was to analyze gene expression profiles of susceptible tomato plants infected with pathogenic and endophytic Cmmstrains. Microarray analysis identified 122 genes that were differentially expressed during early stages of infection. Cmm activated typical basal defense responses in the host including induction of defense-related genes, production of scavenging of free oxygen radicals, enhanced protein turnover and hormone synthesis. Proteomic investigation of the Cmm-tomato interaction was performed with Multi-Dimensional Protein Identification Technology (MudPIT) and mass spectroscopy. A wide range of enzymes secreted by Cmm382, including cell-wall degrading enzymes and a large group of serine proteases from different families were identified in the xylem sap of infected tomato. Based on proteomic results, the expression pattern of selected bacterial virulence genes and plant defense genes were examined by qRT-PCR. Expression of the plasmid-borne cellulase (celA), serine protease (pat-1) and serine proteases residing on the chp/tomA pathogenicity island (chpCandppaA), were significantly induced within 96 hr after inoculation. Transcription of chromosomal genes involved in cell wall degradation (i.e., pelA1, celB, xysA and xysB) was also induced in early infection stages. The second objective was to identify by VIGS technology host genes affecting Cmm multiplication and appearance of disease symptoms in plant. VIGS screening showed that out of 160 tomato genes, which could be involved in defense-related signaling, suppression of 14 genes led to increase host susceptibility. Noteworthy are the genes Snakin-2 (inhibitor of Cmm growth) and extensin-like protein (ELP) involved in cell wall fortification. To further test the significance of Snakin -2 and ELP in resistance towards Cmm, transgenic tomato plants over-expressing the two genes were generated. These plants showed partial resistance to Cmm resulting in a significant delay of the wilt symptoms and reduction in size of canker lesion compared to control. Furthermore, colonization of the transgenic plants was significantly lower. The third objective was to assess the involvement of ethylene (ET), jasmonate (JA) and salicylic acid (SA) in Cmm infection. Microarray and proteomic studies showed the induction of enzymes involved in ET and JA biosynthesis. Cmm promoted ET production 8 days after inoculation and SIACO, a key enzyme of ET biosynthesis, was upregulated. Inoculation of the tomato mutants Never ripe (Nr) impaired in ET perception and transgenic plants with reduced ET synthesis significantly delayed wilt symptoms as compared to the wild-type plants. The retarded wilting in Nr plants was shown to be a specific effect of ET insensitivity and was not due to altered expression of defense related genes, reduced bacterial population or decrease in ethylene biosynthesis . In contrast, infection of various tomato mutants impaired in JA biosynthesis (e.g., def1, acx1) and JA insensitive mutant (jai1) yielded unequivocal results. The fourth objective was to determine the role of cell wall degrading enzymes produced by Cmm in xylem colonization and symptoms development. A significance increase (2 to 7 fold) in expression of cellulases (CelA, CelB), pectate lyases (PelA1, PelA2), polygalacturonase and xylanases (XylA, XylB) was detected by qRT-PCR and by proteomic analysis of the xylem sap. However, with the exception of CelA, whose inactivation led to reduced wilt symptoms, inactivation of any of the other cell wall degrading enzymes did not lead to reduced virulence. Results achieved emphasized the complexity involved in Cmm-tomato interactions. Nevertheless they provide the basis for additional research which will unravel the mechanism of Cmm pathogenicity and formulating disease control measures.
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Olszewski, Neil, and David Weiss. Role of Serine/Threonine O-GlcNAc Modifications in Signaling Networks. United States Department of Agriculture, September 2010. http://dx.doi.org/10.32747/2010.7696544.bard.
Повний текст джерелаАнотація:
Significant evidence suggests that serine/threonine-O-linked N-acetyl glucosamine0-(GlcNAc) modifications play a central role in the regulation of plant signaling networks. Forexample, mutations in SPINDLY,) SPY (an O-GlcNAc transferase,) OGT (promote gibberellin GA) (signal transduction and inhibit cytokinin responses. In addition, mutating both Arabidopsis OGTsSEC (and SPY) causes embryo lethality. The long-term goal of this research is to elucidate the mechanism by which Arabidopsis OGTs regulate signaling networks. This project investigated the mechanisms of O-GlcNAc regulation of cytokinin and gibberellin signaling, identified additional processes regulated by this modification and investigated the regulation of SEC activity. Although SPY is a nucleocytoplasmic protein, its site of action and targets were unknown. Severalstudies suggested that SPY acted in the nucleus where it modified nuclear components such as the DELLA proteins. Using chimeric GFP-SPY fused to a nuclear-export signal or to a nuclear-import signal, we showed that cytosolic, but not nuclear SPY, regulated cytokinin and GA signaling. We also obtained evidence suggesting that GA and SPY affect cytokinin signaling via a DELLA-independent pathway. Although SEC and SPY were believed to have overlapping functions, the role of SEC in cytokinin and GA signaling was unclear. The role of SEC in cytokinin and GA responses was investigated by partially suppressing SPY expression in secplants using a synthetic Spymicro RNA miR(SPY). The possible contribution of SEC to the regulation of GA and cytokinin signaling wastest by determining the resistance of the miR spy secplants to the GA biosynthesis inhibitor paclobutrazol and to cytokinin. We found that the transgenic plants were resistant to paclobutrazol and to cytokinin, butonlyata level similar to spy. Moreover, expressing SEC under the 35S promoter in spy mutant did not complement the spy mutation. Therefore, we believe that SEC does not act with SPY to regulate GA or cytokinin responses. The cellular targets of Spy are largely unknown. We identified the transcription factor TCP15 in a two-hybrid screen for SPY-interacting proteins and showed that both TCP15 and its closely homolog TCP14 were O-GlcNAc modified by bacterially-produced SEC. The significance of the interaction between SPY and these TCPs was examined by over-expressing the minwild-type and spy-4plants. Overexpression of TCP14 or TCP15 in wild-type background produced phenotypes typical of plants with increased cytokinin and reduced GA signaling. TCP14 overexpression phenotypes were strongly suppressed in the spy background, suggesting that TCP14 and TCP15 affect cytokinin and GA signaling and that SPY activates them. In agreement with this hypothesis, we created a tcp14tcp15 double mutant and found that it has defects similar to spyplants. In animals, O-GlcNAc modification is proposed to regulate the activity of the nuclear pore. Therefore, after discovering that SEC modified a nucleoporinNUP) (that also interacts with SPY, we performed genetic experiments exploring the relationship between NUPs and SPY nupspy double mutants exhibited phenotypes consistent with SPY and NUPs functioning in common processes and nupseeds were resistant to GA biosynthesis inhibitors. All eukaryotic OGTs have a TPR domain. Deletion studies with bacterially-expressed SEC demonstrated SEC'sTPR domain inhibits SEC enzymatic activity. Since the TPR domain interacts with other proteins, we propose that regulatory proteins regulate OGT activity by binding and modulating the inhibitory activity of the TPR domain.
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Dubcovsky, Jorge, Tzion Fahima, and Ann Blechl. Molecular characterization and deployment of the high-temperature adult plant stripe rust resistance gene Yr36 from wheat. United States Department of Agriculture, November 2013. http://dx.doi.org/10.32747/2013.7699860.bard.
Повний текст джерелаАнотація:
Stripe rust, caused by Puccinia striiformis f. sp. tritici is one of the most destructive fungal diseases of wheat. Virulent races that appeared within the last decade caused drastic cuts in yields. The incorporation of genetic resistance against this pathogen is the most cost-effective and environmentally friendly solution to this problem. However, race specific seedling resistance genes provide only a temporary solution because fungal populations rapidly evolve to overcome this type of resistance. In contrast, high temperature adult plant (HTAP) resistance genes provide a broad spectrum resistance that is partial and more durable. The cloning of the first wheat HTAP stripe rust resistance gene Yr36 (Science 2009, 323:1357), funded by our previous (2007-2010) BARD grant, provided us for the first time with an entry point for understanding the mechanism of broad spectrum resistance. Two paralogous copies of this gene are tightly linked at the Yr36 locus (WKS1 and WKS2). The main objectives of the current study were to characterize the Yr36 (WKS) resistance mechanism and to identify and characterize alternative WKSgenes in wheat and wild relatives. We report here that the protein coded by Yr36, designated WKS1, that has a novel architecture with a functional kinase and a lipid binding START domain, is localized to chloroplast. Our results suggest that the presence of the START domain may affect the kinase activity. We have found that the WKS1 was over-expressed on leaf necrosis in wheat transgenic plants. When the isolated WKS1.1 splice variant transcript was transformed into susceptible wheat it conferred resistance to stripe rust, but the truncated variant WKS1.2 did not confer resistance. WKS1.1 and WKS1.2 showed different lipid binding profiling. WKS1.1 enters the chloroplast membrane, while WKS1.2 is only attached outside of the chloroplast membrane. The ascorbate peroxidase (APX) activity of the recombinant protein of TmtAPXwas found to be reduced by WKS1.1 protein in vitro. The WKS1.1 mature protein in the chloroplast is able to phosphorylate TmtAPXprotein in vivo. WKS1.1 induced cell death by suppressing APX activity and reducing the ability of the cell to detoxify reactive oxygen. The decrease of APX activity reduces the ability of the plant to detoxify the reactive H2O2 and is the possible mechanism underlying the accelerated cell death observed in the transgenic plants overexpressing WKS1.1 and in the regions surrounding a stripe rust infection in the wheat plants carrying the natural WKS1.1 gene. WKS2 is a nonfunctional paralog of WKS1 in wild emmer wheat, probably due to a retrotransposon insertion close to the alternative splicing site. In some other wild relatives of wheat, such as Aegilops comosa, there is only one copy of this gene, highly similar to WKS2, which is lucking the retrotransposon insertion. WKS2 gene present in wheat and WKS2-Ae from A. showed a different pattern of alternative splice variants, regardless of the presence of the retrotransposon insertion. Susceptible Bobwhite transformed with WKS2-Ae (without retrotansposon insertion in intron10), which derived from Aegilops comosaconferred resistance to stripe rust in wheat. The expression of WKS2-Ae in transgenic plants is up-regulated by temperature and pathogen infection. Combination of WKS1 and WKS2-Ae shows improved stripe rust resistance in WKS1×WKS2-Ae F1 hybrid plants. The obtained results show that WKS1 protein is accelerating programmed cell death observed in the regions surrounding a stripe rust infection in the wheat plants carrying the natural or transgenic WKS1 gene. Furthermore, characterization of the epistatic interactions of Yr36 and Yr18 demonstrated that these two genes have additive effects and can therefore be combined to increase partial resistance to this devastating pathogen of wheat. These achievements may have a broad impact on wheat breeding efforts attempting to protect wheat yields against one of the most devastating wheat pathogen.
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Shmulevich, Itzhak, Shrini Upadhyaya, Dror Rubinstein, Zvika Asaf, and Jeffrey P. Mitchell. Developing Simulation Tool for the Prediction of Cohesive Behavior Agricultural Materials Using Discrete Element Modeling. United States Department of Agriculture, October 2011. http://dx.doi.org/10.32747/2011.7697108.bard.
Повний текст джерелаАнотація:
The underlying similarity between soils, grains, fertilizers, concentrated animal feed, pellets, and mixtures is that they are all granular materials used in agriculture. Modeling such materials is a complex process due to the spatial variability of such media, the origin of the material (natural or biological), the nonlinearity of these materials, the contact phenomenon and flow that occur at the interface zone and between these granular materials, as well as the dynamic effect of the interaction process. The lack of a tool for studying such materials has limited the understanding of the phenomena relevant to them, which in turn has led to energy loss and poor quality products. The objective of this study was to develop a reliable prediction simulation tool for cohesive agricultural particle materials using Discrete Element Modeling (DEM). The specific objectives of this study were (1) to develop and verify a 3D cohesionless agricultural soil-tillage tool interaction model that enables the prediction of displacement and flow in the soil media, as well as forces acting on various tillage tools, using the discrete element method; (2) to develop a micro model for the DEM formulation by creating a cohesive contact model based on liquid bridge forces for various agriculture materials; (3) to extend the model to include both plastic and cohesive behavior of various materials, such as grain and soil structures (e.g., compaction level), textures (e.g., clay, loam, several grains), and moisture contents; (4) to develop a method to obtain the parameters for the cohesion contact model to represent specific materials. A DEM model was developed that can represent both plastic and cohesive behavior of soil. Soil cohesive behavior was achieved by considering tensile force between elements. The developed DEM model well represented the effect of wedge shape on soil behavior and reaction force. Laboratory test results showed that wedge penetration resistance in highly compacted soil was two times greater than that in low compacted soil, whereas DEM simulation with parameters obtained from the test of low compacted soil could not simply be extended to that of high compacted soil. The modified model took into account soil failure strength that could be changed with soil compaction. A three dimensional representation composed of normal displacement, shear failure strength and tensile failure strength was proposed to design mechanical properties between elements. The model based on the liquid bridge theory. An inter particle tension force measurement tool was developed and calibrated A comprehensive study of the parameters of the contact model for the DEM taking into account the cohesive/water-bridge was performed on various agricultural grains using this measurement tool. The modified DEM model was compared and validated against the test results. With the newly developed model and procedure for determination of DEM parameters, we could reproduce the high compacted soil behavior and reaction forces both qualitatively and quantitatively for the soil conditions and wedge shapes used in this study. Moreover, the effect of wedge shape on soil behavior and reaction force was well represented with the same parameters. During the research we made use of the commercial PFC3D to analyze soil tillage implements. An investigation was made of three different head drillers. A comparison of three commonly used soil tillage systems was completed, such as moldboard plow, disc plow and chisel plow. It can be concluded that the soil condition after plowing by the specific implement can be predicted by the DEM model. The chisel plow is the most economic tool for increasing soil porosity. The moldboard is the best tool for soil manipulation. It can be concluded that the discrete element simulation can be used as a reliable engineering tool for soil-implement interaction quantitatively and qualitatively.
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Tsidylo, Ivan M., Serhiy O. Semerikov, Tetiana I. Gargula, Hanna V. Solonetska, Yaroslav P. Zamora, and Andrey V. Pikilnyak. Simulation of intellectual system for evaluation of multilevel test tasks on the basis of fuzzy logic. CEUR Workshop Proceedings, June 2021. http://dx.doi.org/10.31812/123456789/4370.
Повний текст джерелаАнотація:
The article describes the stages of modeling an intelligent system for evaluating multilevel test tasks based on fuzzy logic in the MATLAB application package, namely the Fuzzy Logic Toolbox. The analysis of existing approaches to fuzzy assessment of test methods, their advantages and disadvantages is given. The considered methods for assessing students are presented in the general case by two methods: using fuzzy sets and corresponding membership functions; fuzzy estimation method and generalized fuzzy estimation method. In the present work, the Sugeno production model is used as the closest to the natural language. This closeness allows for closer interaction with a subject area expert and build well-understood, easily interpreted inference systems. The structure of a fuzzy system, functions and mechanisms of model building are described. The system is presented in the form of a block diagram of fuzzy logical nodes and consists of four input variables, corresponding to the levels of knowledge assimilation and one initial one. The surface of the response of a fuzzy system reflects the dependence of the final grade on the level of difficulty of the task and the degree of correctness of the task. The structure and functions of the fuzzy system are indicated. The modeled in this way intelligent system for assessing multilevel test tasks based on fuzzy logic makes it possible to take into account the fuzzy characteristics of the test: the level of difficulty of the task, which can be assessed as “easy”, “average", “above average”, “difficult”; the degree of correctness of the task, which can be assessed as “correct”, “partially correct”, “rather correct”, “incorrect”; time allotted for the execution of a test task or test, which can be assessed as “short”, “medium”, “long”, “very long”; the percentage of correctly completed tasks, which can be assessed as “small”, “medium”, “large”, “very large”; the final mark for the test, which can be assessed as “poor”, “satisfactory”, “good”, “excellent”, which are included in the assessment. This approach ensures the maximum consideration of answers to questions of all levels of complexity by formulating a base of inference rules and selection of weighting coefficients when deriving the final estimate. The robustness of the system is achieved by using Gaussian membership functions. The testing of the controller on the test sample brings the functional suitability of the developed model.