A Random Model for Micro-Slip Between Nominally Flat Surfaces

1997 ◽  
Vol 119 (4) ◽  
pp. 726-732 ◽  
Author(s):  
S. Bjo¨rklund
Keyword(s):  
Standard Deviation ◽  
Random Model ◽  
Surface Model ◽  
Height Distribution ◽  
Asperity Height ◽  
Random Surface ◽  
Tangential Load ◽  
Flat Surfaces ◽  
The Individual ◽  
Elastic Surfaces

A random surface model has been developed for the deformations of contacting surfaces subjected to both normal and tangential load. The model is restricted to nominally flat (rough) elastic surfaces in contact with perfectly flat (smooth) elastic surfaces. The deformations of the asperities are assumed to be independent of each other and the heights of the asperities are assumed to be randomly distributed. Depending on the height of an asperity, it will either slip or stick. The relation between tangential deformation and load will consequently be non-linear and this effect is often named micro-slip. Results are presented for two types of deformation laws for the individual asperities, with three different asperity height distributions. The results show typical micro-slip behaviour, independent of both the individual asperity deformation and the type of asperity height distribution. The influence of the standard deviation of asperity heights is strong and is an important factor when determining the micro-slip of nominally flat surfaces in contact.

Analysis of contact and bending stiffness for Curvic couplings considering contact angle and surface roughness

2019 ◽  
Vol 233 (6) ◽  
pp. 1257-1267 ◽  
Author(s):  
Younghun Yu ◽  
Bora Lee ◽  
Yongjoo Cho
Keyword(s):  
Surface Roughness ◽  
Contact Angle ◽  
Standard Deviation ◽  
Bending Stiffness ◽  
Height Distribution ◽  
Average Radius ◽  
Asperity Height ◽  
Surface Parameter ◽  
Tangential Stiffness ◽  
Nominal Contact Area

This paper develops a method for calculating the contact and bending stiffness of a Curvic coupling, and investigates stiffness changes according to the coupling shape and surface roughness characteristics. The surface of the on-site Curvic coupling is chosen as reference for a most accurate simulation. The three parameters representing the surface roughness characteristics—the standard deviation of the asperity height distribution, the average radius of asperities, and the density of asperity on the nominal contact area—are calculated with a profile of the coupling surface through a random process: the contact problem between rough surfaces is tackled using the Greenwood-Williamson model, the Curvic coupling is modeled assuming that it has as many teeth as possible within the machining limits depending on the contact angle, and the tangential stiffness resulting from the contact angle is calculated by dividing into the stick and slip regions, and is taken into account in terms of total stiffness. With this, results showed that using Curvic couplings reduces stiffness than using flat disc couplings because of the contact angle, and that the standard deviation of rough surface height is the most crucial surface parameter affecting stiffness.

Generation of a 3D model of the inside volume of shoes for e-commerce applications using industrial X-ray computed tomography

2021 ◽  
Author(s):  
J Wittmann ◽  
G Herl ◽  
J Hiller
Keyword(s):  
Computed Tomography ◽  
3D Model ◽  
Region Growing ◽  
Surface Model ◽  
Economic Potential ◽  
X Ray ◽  
Internet Users ◽  
Surface Data ◽  
X Ray Computed ◽  
The Individual

Abstract In 2018, 47 % of global internet users had purchased footwear products through the internet, making it the second most popular online shopping category worldwide right after clothing with 57 %. In the same year, on average, about every sixth parcel delivered in Germany (16.3 %) was returned. With the effort and costs that are associated with the return of shoes, the objective of reducing the number of returns for shoes promises an enormous economic potential and helps to reduce the CO2 emissions due to a lower trafic volume. This paper presents a workflow for determining the inside volume surface of shoes using industrial X-ray computed tomography (CT). The fundamental idea is based on the Region Growing (RG) method for the segmentation of the shoe's inner volume. Experiments are performed to illustrate the correlation of image quality and segmentation result. After obtaining the 3D surface model of an individual foot, the inner volume surface data of a scanned shoe can then be registered and evaluated in order to provide a reliable feedback for the customer regarding the accuracy of fit of a shoe and the individual foot on the basis of an overall "metric of comfort" before buying online. This step is not part of the work at hand. Conclusions are drawn and suggestions for improving the robustness and the exibility of the workflow are given, so it can be adapted to various shoe types and implemented in a fully automated measurement process in the future.

scholarly journals AN OBJECT-BASED WORKFLOW DEVELOPED TO EXTRACT AQUACULTURE PONDS FROM AIRBORNE LIDAR DATA: A TEST CASE IN CENTRAL VISAYAS, PHILIPPINES

2016 ◽  
Vol XLI-B8 ◽  
pp. 1147-1152 ◽  
Author(s):  
R. A. Loberternos ◽  
W. P. Porpetcho ◽  
J. C. A. Graciosa ◽  
R. R. Violanda ◽  
A. G. Diola ◽  
...  
Keyword(s):  
Detection Algorithm ◽  
The Philippines ◽  
Airborne Lidar ◽  
Surface Model ◽  
Lidar Data ◽  
Flat Surfaces ◽  
Water Classification ◽  
Object Based ◽  
Aquaculture Ponds ◽  
Model Layer

Traditional remote sensing approach for mapping aquaculture ponds typically involves the use of aerial photography and high resolution images. The current study demonstrates the use of object-based image processing and analyses of LiDAR-data-generated derivative images with 1-meter resolution, namely: CHM (canopy height model) layer, DSM (digital surface model) layer, DTM (digital terrain model) layer, Hillshade layer, Intensity layer, NumRet (number of returns) layer, and Slope layer. A Canny edge detection algorithm was also performed on the Hillshade layer in order to create a new image (Canny layer) with more defined edges. These derivative images were then used as input layers to perform a multi-resolution segmentation algorithm best fit to delineate the aquaculture ponds. In order to extract the aquaculture pond feature, three major classes were identified for classification, including land, vegetation and water. Classification was first performed by using assign class algorithm to classify Flat Surfaces to segments with mean Slope values of 10 or lower. Out of these Flat Surfaces, assign class algorithm was then performed to determine Water feature by using a threshold value of 63.5. The segments identified as Water were then merged together to form larger bodies of water which comprises the aquaculture ponds. The present study shows that LiDAR data coupled with object-based classification can be an effective approach for mapping coastal aquaculture ponds. The workflow currently presented can be used as a model to map other areas in the Philippines where aquaculture ponds exist.

scholarly journals Design and development of a multichannel potentiometer for monitoring an electrode array and its application in flow analysis

2002 ◽  
Vol 24 (4) ◽  
pp. 105-110 ◽  
Author(s):  
Jarbas J. R. Rohwedder ◽  
Celio Pasquini ◽  
Ivo M. Raimundo, Jr. ◽  
M. Conceiçao ◽  
B. S. M. Montenegro ◽  
...  
Keyword(s):  
Standard Deviation ◽  
Flow Analysis ◽  
Reference Electrode ◽  
Electrode Array ◽  
Ion Selective Electrodes ◽  
Electrode Arrays ◽  
Figures Of Merit ◽  
Flow Through ◽  
The Individual ◽  
Intense Signal

A versatile potentiometer that works with electrode arrays in flow injection and/or monosegmented flow systems is described. The potentiometer is controlled by a microcomputer that allows individual, sequential multiplexed or random accesses to eight electrodes while employing only one reference electrode. The instrument was demonstrated by monitoring an array of seven flow-through ion-selective electrodes for Ag+and for three electrodes for Cl-, Ca2+and K+. The figures of merit of the individual and multiplexed (summed) readings of the electrode array were compared. The absolute standard deviation of the measurements made by summing the potential of two or more electrodes was maintained constant, thus improving the precision of the measurements. This result shows that an attempt to combine the signals of the electrodes to produce a more intense signal in the Hadamard strategy is feasible and accompanied by a proportional improvement in the precision of individual measurements. The preliminary tests suggest that the system can allow for 270 determinations per hour, with a linear range from1.0×10−2to1.0×10−4mol l-1for the three di¡erent analytes. Detection limits were estimated as3.1×10−5,3.0×10−6and1.0×10−5mol l-1for Cl-, Ca2+and K+, respectively.

scholarly journals A NEW MASK FOR AUTOMATIC BUILDING DETECTION FROM HIGH DENSITY POINT CLOUD DATA AND MULTISPECTRAL IMAGERY

2017 ◽  
Vol IV-4/W4 ◽  
pp. 89-96 ◽  
Author(s):  
M. Awrangjeb ◽  
F. U. Siddiqui
Keyword(s):  
Surface Model ◽  
Building Detection ◽  
Multispectral Imagery ◽  
Residential Areas ◽  
Existing Building ◽  
Cloud Data ◽  
Flat Surfaces ◽  
Detection Techniques ◽  
Gradient Function ◽  
Dominant Direction

In complex urban and residential areas, there are buildings which are not only connected with and/or close to one another but also partially occluded by their surrounding vegetation. Moreover, there may be buildings whose roofs are made of transparent materials. In transparent buildings, there are point returns from both the ground (or materials inside the buildings) and the rooftop. These issues confuse the previously proposed building masks which are generated from either ground points or non-ground points. The normalised digital surface model (nDSM) is generated from the non-ground points and usually it is hard to find individual buildings and trees using the nDSM. In contrast, the primary building mask is produced using the ground points, thereby it misses the transparent rooftops. This paper proposes a new building mask based on the non-ground points. The dominant directions of non-ground lines extracted from the multispectral imagery are estimated. A dummy grid with the target mask resolution is rotated at each dominant direction to obtain the corresponding height values from the non-ground points. Three sub-masks are then generated from the height grid by estimating the gradient function. Two of these sub-masks capture planar surfaces whose height remain constant in along and across the dominant direction, respectively. The third sub-mask contains only the flat surfaces where the height (ideally) remains constant in all directions. All the sub-masks generated in all estimated dominant directions are combined to produce the candidate building mask. Although the application of the gradient function helps in removal of most of the vegetation, the final building mask is obtained through removal of planar vegetation, if any, and tiny isolated false candidates. Experimental results on three Australian data sets show that the proposed method can successfully remove vegetation, thereby separate buildings from occluding vegetation and detect buildings with transparent roof materials. While compared to existing building detection techniques, the proposed technique offers higher objectbased completeness, correctness and quality, specially in complex scenes with aforementioned issues. It is not only capable of detecting transparent buildings, but also small garden sheds which are sometimes as small as 5&amp;thinsp;m<sup>2</sup> in area.

EVALUATION OF THE SKELETAL AGE METHOD OF ESTIMATING CHILDREN'S DEVELOPMENT

PEDIATRICS ◽  
1954 ◽  
Vol 13 (2) ◽  
pp. 165-173
Author(s):  
DONALD MAINLAND
Keyword(s):  
Standard Deviation ◽  
Assessment Method ◽  
Systematic Difference ◽  
Skeletal Age ◽  
Nutrition Survey ◽  
Quick Method ◽  
Age Assessment ◽  
Variable Error ◽  
Significant Difference ◽  
The Individual

An observer's variable error in skeletal age assessment of hand RGs (i.e., the irregular ion between independent readings of the same film) was studied on 1,124 readings of 326 films from 233 children aged 16 months to 17 years. seventy-nine of the RGs were full-size reproductions in Macyr's Nutrition and Chemical Growth in Childhood; the remainder were actual films of children in Halifax, Canada (healthy Orphanage residents and children examined in a nutrition survey). There was no significant difference in variable error associated with the atlas (Todd, Greulich-Pyle), age of child, sex, differences between skeletal and chronologic age, differences between children, or differences between RGs of the same child, except for a tendency in the Macy Series for the poorest reproductions to have a larger variable error than the best reproductions. ions. In most readings the individual indicators were assessed separately and the results averaged, but a quicker method (over-all appraisal) did not produce a significantly different variable error. The quick method may be useful in large surveys, although it appears too coarse for the study of individual children. The observer's variable error was expressed by standard deviations of approximately three months (Macy Series—both atlases; Nutritirn Series—Greulich-Pyle atlas) and four months (Orphanage Series—both atlases). With a standard deviation of three months an assessor must affix an error of ± 8.3 months to his estimate of a child's progress in skeletal age, in order to obtain confidence limits with 95% probability. If his standard deviation is four months he must allow ± 11.1 months. For evaluation of the assessment method, many observers' estimates of variable error are needed, and an appeal for data is issued. After more than 1200 readings had been made the observer's practice lapsed for about a year. Reassessment of a random sample of RGs then showed, besides variable error, a mean systematic difference of approximately three months from the previous readings of the same films with the same atlas. To avoid this risk, any two films that are to be assessed for skeletal progress should be read within a few weeks of each other, and special precautions are therefore necessary to secure independence of the two readings.

scholarly journals Comparison of Strategies to Manage Stress Considering to Selected Socio-demographic Characteristics of Employees

2018 ◽  
Vol 26 (2) ◽  
pp. 130-136
Author(s):  
Tatiana Lorincová
Keyword(s):  
Gender Differences ◽  
Standard Deviation ◽  
Stress Management ◽  
Management Strategies ◽  
Demographic Characteristics ◽  
T Test ◽  
Brief Cope ◽  
Common Strategy ◽  
Religiosity And Spirituality ◽  
The Individual

The presented paper deals with the analysis of selected stress management strategies considering to gender and position in organization in which individual employees work. The aim of the paper is to compare the ways of managing and processing the stressful situations, as well as their variability with regard to the group of respondents, their inclusion in the organization (manager or executive employee) and the size of organization (small and medium organization). The research was conducted by using two methodologies, namely Brief COPE from Carver (1997) and SVF 78 by Janke and Erdmann (2003). The research sample consisted of 130 respondents aged 19 to 63 (mean age 40.38 with a standard deviation of 6.73), namely 53.8% of males and 47.2% of women. The research sample consisted of executive employees (49.2%) and managers (50.8%) working in a small and medium-sized organization. The research results were analyzed by t-test for two independent samples, namely the individual stress management strategies were compared. We found statistically significant differences in the level of control of the situation, self-blaming, POZ 1 and NEG among executive employees and managers. At the level of perseverance, self-blaming, religiosity and spirituality, and NEG we found statistically significant gender differences. Comparison of employees working in a small and medium-sized organization has demonstrated the existence of statistically significant differences in levels of underestimation, negation, ventilation and self-blaming. The most common strategy of stress management was the strategy of self-blaming, given the analyzed socio-demographic characteristics of the respondents.

scholarly journals Internal consistency of the Regional Brewer Calibration Centre for Europe triad during the period 2005–2016

2018 ◽  
Vol 11 (7) ◽  
pp. 4059-4072 ◽  
Author(s):  
Sergio Fabián León-Luis ◽  
Alberto Redondas ◽  
Virgilio Carreño ◽  
Javier López-Solano ◽  
Alberto Berjón ◽  
...  
Keyword(s):  
Standard Deviation ◽  
Relative Standard Deviation ◽  
Data Sets ◽  
Individual Values ◽  
Relative Standard ◽  
The World ◽  
The Mean ◽  
The Individual ◽  
Ozone Column

Abstract. Total ozone column measurements can be made using Brewer spectrophotometers, which are calibrated periodically in intercomparison campaigns with respect to a reference instrument. In 2003, the Regional Brewer Calibration Centre for Europe (RBCC-E) was established at the Izaña Atmospheric Research Center (Canary Islands, Spain), and since 2011 the RBCC-E has transferred its calibration based on the Langley method using travelling standard(s) that are wholly and independently calibrated at Izaña. This work is focused on reporting the consistency of the measurements of the RBCC-E triad (Brewer instruments #157, #183 and #185) made at the Izaña Atmospheric Observatory during the period 2005–2016. In order to study the long-term precision of the RBCC-E triad, it must be taken into account that each Brewer takes a large number of measurements every day and, hence, it becomes necessary to calculate a representative value of all of them. This value was calculated from two different methods previously used to study the long-term behaviour of the world reference triad (Toronto triad) and Arosa triad. Applying their procedures to the data from the RBCC-E triad allows the comparison of the three instruments. In daily averages, applying the procedure used for the world reference triad, the RBCC-E triad presents a relative standard deviation equal to σ = 0.41 %, which is calculated as the mean of the individual values for each Brewer (σ157 = 0.362 %, σ183 = 0.453 % and σ185 = 0.428 %). Alternatively, using the procedure used to analyse the Arosa triad, the RBCC-E presents a relative standard deviation of about σ = 0.5 %. In monthly averages, the method used for the data from the world reference triad gives a relative standard deviation mean equal to σ = 0.3 % (σ157 = 0.33 %, σ183 = 0.34 % and σ185 = 0.23 %). However, the procedure of the Arosa triad gives monthly values of σ = 0.5 %. In this work, two ozone data sets are analysed: the first includes all the ozone measurements available, while the second only includes the simultaneous measurements of all three instruments. Furthermore, this paper also describes the Langley method used to determine the extraterrestrial constant (ETC) for the RBCC-E triad, the necessary first step toward accurate ozone calculation. Finally, the short-term or intraday consistency is also studied to identify the effect of the solar zenith angle on the precision of the RBCC-E triad.

Evaluation of Milkoscan 104 Infrared Milk Analyzer

1980 ◽  
Vol 63 (5) ◽  
pp. 973-980
Author(s):  
F R Van De Voort
Keyword(s):  
Molecular Weight ◽  
Regression Analysis ◽  
Standard Deviation ◽  
Linear Regression Analysis ◽  
Average Molecular Weight ◽  
Important Variable ◽  
Standard Errors ◽  
Milk Component ◽  
Mean Differences ◽  
The Individual

Abstract The Milkoscan 104, a single cell, dual wavelength infrared milk analyzer, was assessed to see if it would meet the newly set AOAC specifications for accuracy and reproducibility required for official sanctioning of the instrument for milk component analysis. This assessment was carried out using herd, individual cow, commercial, and composite random milks, and produced mean differences and standard deviations of difference of &lt;0.02% and ±0.02% for reproducibility and &lt;0.05% and ±0.06% for accuracy. Results outside these values were encountered in the individual cow milks, for which the instrument was not specifically calibrated. The average molecular weight of the milkfat was an important variable because 2 anomalous milks were present in the calibration milks, thus restricting the overall accuracy obtainable. Linear regression analysis of chemical vs instrumental results showed good linearity and provided standard errors of the estimate of the same magnitude as the standard deviation of the differences. A separate assessment of the instrument for within- and between-day variation showed no practical significant differences. Based on the overall results, the Milkoscan 104 was judged to be capable of meeting the AOAC specifications set for fat, protein, and lactose analysis.

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