Mathematical Theory of Processes of Concrete Corrosion

2019 ◽  
pp. 58-63
Keyword(s):  
Experimental Data ◽  
Service Life ◽  
Initial Data ◽  
Mathematical Theory ◽  
Dual Porosity ◽  
Safe Operation ◽  
National Importance ◽  
Concrete Corrosion ◽  
Binding Rate ◽  
Chemical Type

Forecasting the processes of degradation of structures that determine their safe operation (especially in aggressive environments) is a task of national importance, given the significant volumes of structures whose service life is exhausted. The main directions of improving the mathematical theory of concrete corrosion are formulated in the article. For corrosion of chemical type they include: the account of phase transformations, dual porosity system and the use of experimental data on distribution of aggressive components along the depth of a layer of concrete of the operated structures as initial data for forecasting of processes of degradation. The function of the binding rate of the aggressive component under this approach is theoretically justified. The development of general provisions of the principles of building of mathematical models, methods of predicting the processes of degradation of structures makes it possible to combine research in this area and present them as a mathematical theory of corrosion processes of concrete.

scholarly journals Analytical Continuation within the Freundlich Adsorption Model. Comment on Edet, U.A.; Ifelebuegu, A.O. Kinetics, Isotherms, and Thermodynamic Modeling of the Adsorption of Phosphates from Model Wastewater Using Recycled Brick Waste. Processes 2020, 8, 665

Processes ◽  
2021 ◽  
Vol 9 (7) ◽  
pp. 1251
Author(s):  
Michael Vigdorowitsch ◽  
Alexander N. Pchelintsev ◽  
Liudmila E. Tsygankova
Keyword(s):  
Experimental Data ◽  
Power Function ◽  
Thermodynamic Modeling ◽  
Mathematical Theory ◽  
Surface Adsorption ◽  
Analytical Continuation ◽  
Adsorption Model ◽  
Saturation Regime

Using experimental data for the adsorption of phosphates out of wastewater on waste recycled bricks, published independently in MDPI Processes before (2020), this message re-visits the mathematical theory of the Freundlich adsorption model. It demonstrates how experimental data are to be deeper treated to model the saturation regime and to bridge a chasm between those areas where the data fit the Freundlich power function and where a saturation of surface adsorption centers occurs.

scholarly journals IMPROVEMENT OF THE ROUGHNESS FORECASTING MODEL OF COATING OF NON-RIGID ROAD PAVEMENT COATING

2021 ◽  
Vol 4 (164) ◽  
pp. 71-76
Author(s):  
A. Batrakova ◽  
H. Sarkisian ◽  
E. Zakharova
Keyword(s):  
Experimental Data ◽  
Service Life ◽  
Pearson Correlation ◽  
Safety Margin ◽  
Calculated Data ◽  
Statistical Processing ◽  
Theoretical Models ◽  
Rigid Pavement ◽  
Improved Model ◽  
Over Time

To ensure safe, comfortable driving at high speeds, a strong, even surface is required for the entire life of the pavement. In this regard, the issue of predicting changes in the equality of coverage over time is very important. The article considers the peculiarities of changing the longitudinal equality of the road surface. Purpose is to improve the model of forecasting the equality of non-rigid pavement. Methods – analytical and experimental. The analysis of existing decisions on the issue of forecasting the equality of coverage is performed. The most important factors influencing the change in the equality of road coverage have been identified. Based on the analysis of theoretical models and a number of experimental data, an improved model for predicting the equality of coverage of non-rigid pavement is proposed. MathCAD and MS Excel were involved in the development of an improved model that takes into account the most important factors. The model of change of coverage roughness, where increase in the roughness index over time is considered as a function of such parameters, is improved: the modulus of pavement elasticity (actual or required); the number of load cycles for t years of pavement operation; the share of trucks in the traffic flow; the factor of safety margin of the pavement structure. The adequacy of the developed model of changing the roughness of coverage is confirmed by statistical processing of experimental data obtained by the thesis author and other researchers on public roads with different service life, and calculated data under the theoretical model. The Pearson correlation coefficient between experimental and calculated data is more than 0.95, which indicates the adequacy of the developed model. Compared to the well-known models of forecasting coverage roughness, the improved model allows to apply a wider range of values of the general equivalent modulus of elasticity of pavement design (from 100 MPa to 600 MPa) and to receive forecast values of roughness for service life of non-rigid pavement over 5 years.

scholarly journals Strain-Life Assessment of Grainex Mar-M 247 for NASA’s Turbine Seal Test Facility

2004 ◽  
Author(s):  
Irebert R. Delgado ◽  
Gary R. Halford ◽  
Bruce M. Steinetz ◽  
Clare M. Rimnac
Keyword(s):  
Experimental Data ◽  
High Temperature ◽  
High Speed ◽  
Life Assessment ◽  
Current Work ◽  
Test Facility ◽  
Safe Operation ◽  
Jet Engine ◽  
Inspection Interval ◽  
Bolt Holes

NASA’s Turbine Seal Test Facility is used to test air-to-air seals for use primarily in advanced jet engine applications. Combinations of high temperature, high speed, and high pressure limit the disk life, due to the concern of crack initiation in the bolt holes of the Grainex Mar-M 247 disk. The primary purpose of this current work is to determine an inspection interval to ensure safe operation. The current work presents high temperature fatigue strain-life data for test specimens cut from an actual Grainex Mar-M 247 disk. Several different strain-life models were compared to the experimental data including the Manson-Hirschberg Method of Universal Slopes, the Halford-Nachtigall Mean Stress Method, and the Modified Morrow Method. The Halford-Nachtigall Method resulted in only an 18% difference between predicted and experimental results. Using the experimental data at a −99.95% prediction level and the presence of 6 bolt holes it was found that the disk should be inspected after 665 cycles based on a total strain of 0.5% at 649°C.

scholarly journals Retrieval of water vapor profile in the mesosphere from satellite ozone and hydroxyl measurements by the basic dynamic model of mesospheric photochemical system

2009 ◽  
Vol 9 (21) ◽  
pp. 8199-8210 ◽  
Author(s):  
M. Y. Kulikov ◽  
A. M. Feigin ◽  
G. R. Sonnemann
Keyword(s):  
Experimental Data ◽  
Water Vapor ◽  
Initial Data ◽  
Dynamic Model ◽  
Indirect Method ◽  
Dynamic Models ◽  
Vapor Concentration ◽  
Water Vapor Concentration ◽  
Control Parameters ◽  
Photochemical Systems

Abstract. We propose an indirect method for retrieving a number of significant minor gas constituents of the atmosphere. The technique is based on the use of so-called basic dynamic models of atmospheric photochemical systems simplified mathematically correctly in a special manner. It is applied to a mesospheric system describing day evolution of key minor gas constituents at these heights. We take as initial data experimental data of the CRISTA-MAHRSI satellite campaign of August 1997 during which ozone and hydroxyl (O3 and OH) concentrations were measured simultaneously. It is demonstrated that the use of the basic dynamic model allows retrieval of vertical distribution (within the 53–85 km range of heights) of water vapor concentration that is one of the control parameters of the mesospheric photochemistry.

scholarly journals Methodological and computer-based support for choosing underground utility networks renovation method

2018 ◽  
Vol 230 ◽  
pp. 02010
Author(s):  
Dmitriy Goncharenko ◽  
Ihor Shumakov ◽  
Olha Starkova ◽  
Alevtyna Aleinikova ◽  
Revaz Mikautadze
Keyword(s):  
Service Life ◽  
Computer Models ◽  
Software Tools ◽  
Safe Operation ◽  
Multicriterion Optimization ◽  
Repair Method ◽  
The Status ◽  
Computer Based ◽  
Effective Organization

The article is devoted to the methodological and software tools for choosing organizational and technological solutions to maintain sewage collectors in an operable state to increase their service life. Such a tool must take into account a set of factors that affect the operation of sewer collectors and form a system, the implementation of which would improve the existing principles of monitoring the status of sewer collectors, identify effective organization and technological solutions of their renovation by taking into account factors that affect their safe operation, the facilities risk of accidents categories, conditions and parameters of works performance. For determining the optimal options for the renovation of the sewer collector using the developed mathematical and computer models, the results of problems solving were generalized: one-criterion optimization subject to the choice of one repair method; one-criterion optimization subject to the choice of different repair methods for the areas; multicriterion optimization.

Analysis and Design of Multistage Torsion Springs

1971 ◽  
Vol 93 (2) ◽  
pp. 656-658
Author(s):  
H. Libman ◽  
S. Shaanan
Keyword(s):  
Experimental Data ◽  
Service Life ◽  
Close Agreement ◽  
Theoretical Study ◽  
Angular Displacement ◽  
Analysis And Design ◽  
Torsion Spring ◽  
Multi Stage ◽  
Torsion Springs

An experimental and theoretical study of a “multi-stage torsion spring” is presented. The spring is designed for high torsion (25 kg-m), considerable angular displacement (±20 deg), space limitations, considerable service life, linearity, and hysteresis restrictions. Theoretical and experimental data are found to be in very close agreement.

Study on Step Type Vibration Tapping of Superalloy

2014 ◽  
Vol 496-500 ◽  
pp. 401-405
Author(s):  
Feng Qi Han ◽  
Zhi Zun Li ◽  
De Yuan Zhang
Keyword(s):  
Experimental Data ◽  
Service Life ◽  
Torsional Vibration ◽  
Low Frequency ◽  
Spindle Speed ◽  
Cutting Angle ◽  
Step Type

Service life of tap is shorter when low frequency torsional vibration tapping is used to tap on superalloy GH4169. The analysis of experimental data show that excessive repeated cutting times and high friction speed result in rapid wear of tap. In order to avoid above unfavorable factors, step type vibration tapping is proposed, which has larger cutting angle, such as 90°, and lower spindle speed. It was proved by experiments on superalloy GH4169 that service life of tap of step type vibration tapping is about twice of that of common low frequency torsional vibration tapping .

scholarly journals III . Mathematical contributions to the theory of evolution.—XII. On a generalised Theory of alternative Inheritance, with special reference to Mendel's laws

1904 ◽  
Vol 203 (359-371) ◽  
pp. 53-86 ◽  
Keyword(s):  
Experimental Data ◽  
General Theory ◽  
Special Reference ◽  
Mathematical Theory ◽  
Individual Case ◽  
Experimental Results ◽  
Theory Of Evolution ◽  
Original Theory ◽  
Growing Mass ◽  
Mendel’S Laws

It seems likely to be of interest at the present time to consider rather at length a fairly full mathematical theory of the pure gamete. We do not venture to call this theory a generalised Mendelian theory of inheritance, partly because it is not even the most general theory of the pure gamete conceivable, partly because Mendel’s original theory of heredity was perfectly clear and perfectly simple, and is not the theory here developed. The pure and simple Mendelian theory seems to have been discarded in the light of recent experimental results by more than one Mendelian, both in this country and abroad. The original Mendelian theory has been replaced by what are termed “ Mendelian Principles.” In this aspect of investigation the fundamental principles propounded by Mendel are given up, and for each individual case a pure gamete formula of one kind or another is suggested as describing the facts, This formula is then emphasised, modified or discarded, according as it fits well, badly, or not at all with the growing mass of experimental data. It is quite clear that it is impossible while this process is going on to term anything whatever Mendelian as far as theory is concerned.

Probing the Endogenous Ca2+ Buffers at the Presynaptic Terminals of the Crayfish Neuromuscular Junction

2005 ◽  
Vol 94 (1) ◽  
pp. 377-386 ◽  
Author(s):  
Jen-Wei Lin ◽  
Qinghao Fu ◽  
Tariq Allana
Keyword(s):  
Experimental Data ◽  
Neuromuscular Junction ◽  
Action Potential ◽  
Fluorescence Intensity ◽  
High Mobility ◽  
Binding Kinetics ◽  
Binding Rate ◽  
Slow Kinetics ◽  
Crayfish Neuromuscular Junction ◽  
Fluorescence Transients

Ca2+ indicators of varying affinity and mobility were pressure injected into the presynaptic axon of the inhibitor of the crayfish neuromuscular junction (NMJ). Fluorescence transients recorded at a 2-kHz resolution were used to probe physiological parameters governing the decay of fluorescence transients within 100 ms after an action potential (early decay). Blocking Ca2+ extrusion or Ca2+ sequestration processes did not significantly alter early decay, arguing against a role for either mechanism. Fluorescence transients recorded with low mobility or fixed indicators exhibited early decay similar to that recorded with indicators of comparable affinity but high mobility, suggesting that early decay was not due to the rate of Ca2+-indicator diffusion. The extent of early decay correlated closely with the affinity, but not mobility, of the Ca2+ sensitive dyes tested. These results implicate intrinsic buffers with slow Ca2+ binding kinetics as the most likely determinants of early decay. However, computer simulations showed that intrinsic buffers with a slow binding rate are unlikely to be the only ones present in the system because the slow kinetics would be unable to buffer incoming Ca2+ during an action potential and would result in momentary indicator saturation. In fact, experimental data show that the peak amplitude of an action potential activated Ca2+ transient is about 20% of the maximal fluorescence intensity activated by prolonged Ca2+ influx. We conclude that endogenous buffering at the crayfish NMJ includes both fast and slow components, the former being fast enough to compete with fast Ca2+ indicators, and the latter dictating the early decay.

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