Relationship Between the Parameters of an Autoregressive Model and Grinding Wheel Constituents

1973 ◽  
Vol 95 (4) ◽  
pp. 979-982 ◽  
Author(s):  
S. J. Deutsch ◽  
S. M. Wu
Keyword(s):  
Formation Mechanism ◽  
Autoregressive Model ◽  
Grit Size ◽  
Autoregressive Models ◽  
Grinding Wheel ◽  
Relative Contribution ◽  
Wheel Topography ◽  
Designed Experiment ◽  
The Individual

Autoregressive models are developed for eight wheels differing in grit size, hardness, and structure. Using the parameters as responses of a factorially designed experiment, the relative contribution of the wheel constituents to the total wheel topography is related and quantified. Utilizing the effects observed, the individual and interactive roles of the wheel constituents are discussed. From the experimental observations a formation mechanism is suggested.

Stochastic Modeling of Microgrinding Wheel Topography

2013 ◽  
Vol 1 (2) ◽  
Author(s):  
Jacob A. Kunz ◽  
J. Rhett Mayor
Keyword(s):  
Stochastic Model ◽  
Stochastic Modeling ◽  
Process Modeling ◽  
Grinding Wheel ◽  
Analytic Model ◽  
Geometric Accuracy ◽  
Simulation Techniques ◽  
Wheel Topography ◽  
A New Technique ◽  
The Individual

Superabrasive microgrinding wheels are used for jig grinding of microstructures using various grinding approaches. The desire for increased final geometric accuracy in microgrinding leads to the need for improved process modeling and understanding. An improved understanding of the source of wheel topography characteristics leads to better knowledge of the interaction between the individual grits on the wheel and the grinding workpiece. Analytic stochastic modeling of the abrasives in a general grinding wheel is presented as a method to stochastically predict the wheel topography. The approach predicts the probability of the number of grits within a grind wheel, the individual grit locations within a given wheel structure, and the static grit density within the wheel. The stochastic model is compared to numerical simulations that imitate both the assumptions of the analytic model where grits are allowed to overlap and the more realistic scenario of a grind wheel where grits cannot overlap. A new technique of grit relocation through collective rearrangement is used to limit grit overlap. The results show that the stochastic model can accurately predict the probability of the static grit density while providing results two orders of magnitude faster than the numerical simulation techniques. It is also seen that grit overlap does not significantly impact the static grit density allowing for the simpler, faster analytic model to be utilized without sacrificing accuracy.

Characterization and Analysis of Grinding Wheel Topography as a Stochastic Isotropic Surface

1979 ◽  
Vol 101 (2) ◽  
pp. 165-170 ◽  
Author(s):  
F. Nassirpour ◽  
S. M. Wu
Keyword(s):  
Unit Area ◽  
Rake Angle ◽  
Grinding Wheel ◽  
Characteristic Parameters ◽  
Relative Contribution ◽  
Wheel Topography ◽  
Grinding Wheel Topography ◽  
Explicit Procedure ◽  
The Mean ◽  
Factorial Design Analysis

The grinding wheel topography is characterized and analyzed as a stochastic isotropic surface. An explicit procedure is given to check the assumption of surface isotropy. Geometric statistical properties such as the number of active cutting points per unit area, the ratio of real to apparent area of contact, and the mean and root-mean-square rake angle of ten grinding wheels are calculated. Using the characteristic parameters as responses, the relative contribution of the wheel grit size, hardness, and structure to the total wheel topography is quantified by factorial design analysis. The procedure of characterization is also applicable to other homogeneous stochastic isotropic surface.

scholarly journals A mixture autoregressive model based on Gaussian and Student’s t-distributions

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Savi Virolainen
Keyword(s):  
Interest Rate ◽  
Autoregressive Model ◽  
Autoregressive Models ◽  
Federal Funds ◽  
Treasury Bill ◽  
Federal Funds Rate ◽  
Empirical Application ◽  
Model Based ◽  
Interest Rate Spread ◽  
Student’S T

Abstract We introduce a new mixture autoregressive model which combines Gaussian and Student’s t mixture components. The model has very attractive properties analogous to the Gaussian and Student’s t mixture autoregressive models, but it is more flexible as it enables to model series which consist of both conditionally homoscedastic Gaussian regimes and conditionally heteroscedastic Student’s t regimes. The usefulness of our model is demonstrated in an empirical application to the monthly U.S. interest rate spread between the 3-month Treasury bill rate and the effective federal funds rate.

Population Densities Allowed Around Dutch SEVESO Establishments

2000 ◽  
Author(s):  
G. M. H. Laheij ◽  
B. J. M. Ale ◽  
J. G. Post
Keyword(s):  
Population Density ◽  
The Netherlands ◽  
Individual Risk ◽  
Population Densities ◽  
Planning Policy ◽  
Relative Contribution ◽  
Societal Risk ◽  
Dangerous Substances ◽  
The Individual ◽  
Uniform Population

Abstract In the Netherlands, the individual risk and societal risk are used in efforts to reduce the number of people exposed to the effect of an accident at an establishment with dangerous substances. To facilitate the societal risk planning policy an investigation was carried out for the Dutch SEVESO establishments to investigate the possibility of determining a generic uniform population density for the zone between the individual risk contours of 10−5 and 10−6 per year. The indicative limit for the societal risk at this density was not to be exceeded. Also there was to be enough space left for a significantly higher population density outside the individual risk contour of 10−6 per year. The RORISC methodology and the actual data for the 124 Dutch SEVESO establishments were used to determine the generic uniform population density. Based on the data available it can be concluded that the maximum allowed uniform population density in the zone between the individual risk contours of 10−5 and 10−6 per year is lower than one person per hectare. At this density there is no space left for a higher population density outside the individual risk contour of 10−6 per year. For uniform population densities the relative contribution to the societal risk has been found significant up to the individual risk contour of 10−7 per year.

Einfluss der Schärfparameter auf die Schleifscheibentopographie*/Influence of the sharpening parameters on the grinding wheel topography

2019 ◽  
Vol 109 (07-08) ◽  
pp. 582-588
Author(s):  
E. Uhlmann ◽  
A. Muthulingam
Keyword(s):  
Economic Efficiency ◽  
Experimental Investigations ◽  
Grinding Wheel ◽  
Conditioning Process ◽  
Wheel Topography ◽  
Process Reliability ◽  
Grinding Wheel Topography ◽  
The Relationship

Einen wesentlichen Bestandteil der Schleiftechnik ist der Konditionierprozess zur Herstellung der Schleifscheibenform und -schnittigkeit. Durch das Schärfen wird die Bindung zurückgesetzt und der notwendige Schleifkornüberstand und Spanraum geschaffen. Ein CNC-gesteuerter Schärfprozess kann zur prozesssicheren und ressourceneffizienten Einstellung der gewünschten Schleifbelagstopographie genutzt werden. Umfangreiche Schärfuntersuchungen sollen hierbei Aufschluss über die Wirkzusammenhänge zwischen Schärfeinstellgrößen und Schärfergebnis geben.   An essential part of grinding technology is the conditioning process for the generation of the grinding wheel shape and of a sharp topography. Through the sharpening process the required cutting grains are exposed from the bond and sufficient chip space is ensured by putting back the bonding. A CNC-controlled sharpening process can lead to an improvement in process reliability and the economic efficiency. Extensive experimental investigations were carried out to determine the relationship between the sharpening parameters and the sharpening result.

Einfluss der Abrichtgrößen beim Schleifen*/Influence of dressing parameters on the grinding process - Systematic research of dressing parameters on workpiece roughness and surface integrity

2016 ◽  
Vol 106 (01-02) ◽  
pp. 44-50
Author(s):  
T. Lierse ◽  
B. Karpuschewski ◽  
T. R. Kaul
Keyword(s):  
Aluminum Oxide ◽  
Surface Integrity ◽  
Cvd Diamond ◽  
Grinding Wheel ◽  
Systematic Research ◽  
Grinding Process ◽  
Wheel Topography ◽  
Grinding Wheel Topography

Dieser Beitrag zeigt, dass die durch die Abrichtparameter erzeugte Schleifscheibentopographie nicht nur die Oberflächengüte des Werkstücks, sondern auch dessen Eigenspannungszustand in der Werkstückrandzone in weiten Grenzen verändert. Die Untersuchungen zum Abrichten von Korundschleifscheiben mit einer CVD-Diamantformrolle stellen den Zusammenhang zwischen dem Abrichten unterschiedlicher Schleifscheiben zur Bauteilqualität in Form der Oberflächenrautiefe und randzonennahen Eigenspannungen her.   The quality of the workpiece rim is changed by every grinding process. The grinding wheel topography created by the dressing process has not only influence on the workpiece roughness but also on the surface integrity. The pointed research using aluminum oxide abrasive wheels dressed by CVD diamond dressing discs shows a correlation between the dressing parameters, the workpiece roughness and the surface integrity.

scholarly journals Disentangling age-dependent DNA methylation: deterministic, stochastic, and nonlinear

2020 ◽  
Author(s):  
O. Vershinina ◽  
M. Ivanchenko ◽  
M.G. Bacalini ◽  
A. Zaikin ◽  
C. Franceschi
Keyword(s):  
Dna Methylation ◽  
Environmental Factors ◽  
Methylation Level ◽  
Signal To Noise Ratio ◽  
Cross Sectional ◽  
Ample Evidence ◽  
Systematic Assessment ◽  
Relative Contribution ◽  
Age Dependent ◽  
The Individual

ABSTRACTDNA methylation variability arises due to concurrent genetic and environmental influences. Each of them is a mixture of regular and noisy sources, whose relative contribution has not been satisfactorily understood yet. We conduct a systematic assessment of the age-dependent methylation by the signal-to-noise ratio and identify a wealth of “deterministic” CpG probes (about 90%), whose methylation variability likely originates due to genetic and general environmental factors. The remaining 10% of “stochastic” CpG probes are arguably governed by the biological noise or incidental environmental factors. Investigating the mathematical functional relationship between methylation levels and variability, we find that in about 90% of the age-associated differentially methylated positions, the variability changes as the square of the methylation level, whereas in the most of the remaining cases the dependence is linear. Furthermore, we demonstrate that the methylation level itself in more than 15% cases varies nonlinearly with age (according to the power law), in contrast to the previously assumed linear changes. Our findings present ample evidence of the ubiquity of strong DNA methylation regulation, resulting in the individual age-dependent and nonlinear methylation trajectories, whose divergence explains the cross-sectional variability. It may also serve a basis for constructing novel nonlinear epigenetic clocks.

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