scholarly journals Vibration Pattern Related to Transverse Cracks in Rotors

2002 ◽  
Vol 9 (4-5) ◽  
pp. 217-224 ◽  
Author(s):  
Nicolò Bachschmid ◽  
Ezio Tanzi
Keyword(s):  
Thermal Effects ◽  
Transverse Cracks ◽  
Vibration Excitation ◽  
Different Types ◽  
Vibration Pattern ◽  
Rotating Shafts ◽  
Different Shapes

A method for calculating the breathing behavior of transverse cracks of different types in rotating shafts is described. Thermal effects are included. Some results in terms of vibration excitation related to different shapes of cracks are presented.

scholarly journals Research on a Rice Counting Algorithm Based on an Improved MCNN and a Density Map

Entropy ◽  
2021 ◽  
Vol 23 (6) ◽  
pp. 721
Author(s):  
Ao Feng ◽  
Hongxiang Li ◽  
Zixi Liu ◽  
Yuanjiang Luo ◽  
Haibo Pu ◽  
...  
Keyword(s):  
Grain Weight ◽  
Gaussian Kernel ◽  
Density Level ◽  
Thousand Grain Weight ◽  
Original Algorithm ◽  
Different Types ◽  
Different Shapes ◽  
Density Map ◽  
Important Basis ◽  
Adhesion Condition

The thousand grain weight is an index of size, fullness and quality in crop seed detection and is an important basis for field yield prediction. To detect the thousand grain weight of rice requires the accurate counting of rice. We collected a total of 5670 images of three different types of rice seeds with different qualities to construct a model. Considering the different shapes of different types of rice, this study used an adaptive Gaussian kernel to convolve with the rice coordinate function to obtain a more accurate density map, which was used as an important basis for determining the results of subsequent experiments. A Multi-Column Convolutional Neural Network was used to extract the features of different sizes of rice, and the features were fused by the fusion network to learn the mapping relationship from the original map features to the density map features. An advanced prior step was added to the original algorithm to estimate the density level of the image, which weakened the effect of the rice adhesion condition on the counting results. Extensive comparison experiments show that the proposed method is more accurate than the original MCNN algorithm.

A new class of isotropic generators for developing 6-DOF isotropic manipulators

Robotica ◽  
2008 ◽  
Vol 26 (5) ◽  
pp. 619-625 ◽  
Author(s):  
K. Y. Tsai ◽  
T. K. Lee ◽  
Y. S. Jang
Keyword(s):  
Reference Point ◽  
Parallel Manipulators ◽  
Geometric Constraint ◽  
Kinematic Chains ◽  
New Class ◽  
New Methods ◽  
Center Point ◽  
Different Types ◽  
Different Shapes ◽  
Straight Lines

SUMMARYDeveloping 6-DOF isotropic manipulators using isotropic generators is simple and efficient, and isotropic generators can be employed to develop serial, redundant, or parallel isotropic manipulators. An isotropic generator consists of a reference point and six straight lines. The existing generators, however, have one common geometric constraint: the reference point is equidistant from the six straight lines. Some practical isotropic designs might not be obtained due to this constraint. This paper proposes methods for developing new isotropic generators. The generators thus developed are not subject to the constraint, and the new methods allow us to specify the location of the tool center point, the size of the platform or the base, or the shape of isotropic parallel manipulators. Many new generators are presented to develop 6-DOF parallel manipulators with different shapes or different types of kinematic chains.

Rotating Shafts Affected by Transverse Cracks: A Sensitivity Analysis

2008 ◽  
Author(s):  
Nicolo` Bachschmid ◽  
Ezio Tanzi ◽  
Paolo Pennacchi
Keyword(s):  
Sensitivity Analysis ◽  
Element Model ◽  
Dynamical Behaviour ◽  
Crack Model ◽  
Transverse Cracks ◽  
Rotating Shaft ◽  
Shaft Line ◽  
Linear Approach ◽  
Turbo Generator ◽  
Rotating Shafts

The dynamic behaviour of heavy, horizontal axis, rotating shaft-lines affected by transverse cracks can be analysed in the frequency domain by a quasi linear approach, using a simplified breathing crack model applied to a traditional finite element model of the shaft-line. This allows to perform a series of analyses with affordable efforts. The analysis of the modelling procedure allows to define an approximated approach for simulating the dynamical behaviour, which allows to predict the severity of the crack excited vibrations, combined to modal analysis. this answers to the old-age question on how deep a crack must be to be detected by means of vibration measurements. The model of a 320 MW turbo-generator group has been used to perform a numerical sensitivity analysis, in which the vibrations of the shaft-line, and more in detail the vibrations of the shafts in correspondence to the bearings, have been calculated for all possible positions of the crack along the shaftline and for two different values of the depth of the crack. The calculated results confirm the predicted behaviour.

Thermal Effects on Wheel Performance Based on Twin Disc Testing

2020 ◽  
Author(s):  
Dingqing Li ◽  
Monique Stewart
Keyword(s):  
Thermal Effects ◽  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Contact Forces ◽  
Rolling Contact ◽  
Test Machine ◽  
Testing Program ◽  
Different Types ◽  
Different Temperatures ◽  
Surface Performance

Abstract This paper presents the results and findings from a testing program conducted to investigate how temperature at the wheel-rail interface may affect wheel surface performance; i.e., development of rolling contact fatigue (RCF) and wear. Under this testing program, a twin disc test machine was used to test two different types of wheel specimens (cast and forged) under a range of temperatures (ambient to 800° F) and slip ratios from 0 to 0.75 percent. This testing program included a total of 32 tests, covering two wheel materials, four different temperatures, four slip ratios, and various traction coefficients as a ratio of longitudinal and vertical wheel/rail contact forces.

ON GEOMETRIC AND ORTHOGONAL MOMENTS

2000 ◽  
Vol 14 (07) ◽  
pp. 875-894 ◽  
Author(s):  
JUN SHEN ◽  
WEI SHEN ◽  
DANFEI SHEN
Keyword(s):  
Pattern Analysis ◽  
Equivalence Theorem ◽  
Image Features ◽  
Shape Classification ◽  
Orthogonal Moments ◽  
Zero Crossings ◽  
Different Types ◽  
Base Functions ◽  
Different Shapes ◽  
Function Discontinuity

Moments are widely used in pattern recognition, image processing, computer vision and multiresolution analysis. To clarify and to guide the use of different types of moments, we present in this paper a study on the different moments and compare their behavior. After an introduction to geometric, Legendre, Hermite and Gaussian–Hermite moments and their calculation, we analyze at first their behavior in spatial domain. Our analysis shows orthogonal moment base functions of different orders having different number of zero-crossings and very different shapes, therefore they can better separate image features based on different modes, which is very interesting for pattern analysis and shape classification. Moreover, Gaussian–Hermite moment base functions are much more smoothed, they are thus less sensitive to noise and avoid the artifacts introduced by window function discontinuity. We then analyze the spectral behavior of moments in frequency domain. Theoretical and numerical analyses show that orthogonal Legendre and Gaussian–Hermite moments of different orders separate different frequency bands more effectively. It is also shown that Gaussian–Hermite moments present an approach to construct orthogonal features from the results of wavelet analysis. The orthogonality equivalence theorem is also presented. Our analysis is confirmed by numerical results, which are then reported.

scholarly journals ASSESSMENT OF SOME PHYSICAL FACTORS AND DESIGN FEATURES OF ROTORS IN THERMAL EFFECTS CAUSED BY CENTRIFUGATION

2017 ◽  
Vol 20 (3) ◽  
Author(s):  
ALEXEI MAFTULEAC
Keyword(s):  
Thermal Effects ◽  
Heterogeneous Systems ◽  
Chemical Processes ◽  
Physical Factors ◽  
Centrifugal Acceleration ◽  
Design Features ◽  
Highly Dispersed ◽  
Different Types ◽  
Very High

<h1>In separating the components of highly dispersed heterogeneous systems, use is made of centrifuges with very high rotation velocities, this leading to samples heating. The said above is due to the friction of the rotor against the air from the centrifuge chamber to the movement of heating from centrifuge engine towards the samples and to compression of samples liquid. However, heating of samples sensible to temperature can generate in these samples the intensification of some uncontrolled chemical processes. This paper is devoted to the investigation of the increase of centrifuged samples temperature depending on the time and relative centrifugal acceleration for model-samples (water and glycerine) using two constructively different types of rotors. The obtained results can be taken into account when elaborating some more rigorous methods for studying finely-dispersed heterogeneous systems.</h1>

scholarly journals Better to Explain or to Testify? The Position of the Accused as a Source of Oral Evidence in a Criminal Trial in a Comparative Perspective

2021 ◽  
Vol 27 ◽  
pp. 47-77
Author(s):  
Hanna Kuczyńska
Keyword(s):  
Common Law ◽  
Criminal Trial ◽  
Comparative Perspective ◽  
Legal Systems ◽  
Anglo Saxon ◽  
Present Evidence ◽  
Different Types ◽  
Different Shapes ◽  
The Common ◽  
Oral Evidence

In this article the position of the accused as a source of personal evidence in three different European legal systems: Poland, Germany, and England, will be presented. This analysis will be oriented to understand the way of functioning of the two different models of giving statements of fact by the accused at a criminal trial. The main difference is that in the common law model of criminal trial the accused may only present evidence by testifying as a witness speaking about what happened, whereas in the continental model the accused gives a specific personal type of evidence (that in the Anglo-Saxon literature is rather described as “oral evidence”) that is known as explanations. From this differentiation several consequences arise: among others, the possibility of presenting untruthful explanations and presenting many versions of events in the continental model which have to be assessed by the judges. At the same time, the same right of the accused to silence and not to give incriminating evidence applies in both models of criminal trial – however, in two different shapes and with different types of limitations.

Crack Position and Depth Identification in Rotating Shafts: Part 2 — Experimental Results

2005 ◽  
Author(s):  
Nicolo` Bachschmid ◽  
Paolo Pennacchi ◽  
Ezio Tanzi
Keyword(s):  
Dynamical Behavior ◽  
Industrial Applications ◽  
Experimental Results ◽  
Crack Identification ◽  
Identification Method ◽  
Different Types ◽  
Rotating Shafts ◽  
Short Time ◽  
Crack Position ◽  
Deep Crack

This paper presents the experimental validation of a model based transverse crack identification method suitable for industrial machines, described in part 1. The method is validated by experimental results obtained on two test rigs, which were expressly designed for investigating the dynamical behavior of cracked horizontal rotors. On the first test rig, only one crack type is considered, while on the second one three different types of crack have been analyzed: the first is a slot, therefore not actually a crack since it has not the typical breathing behavior, the second a small crack (14% of the diameter) and the third a deep crack (47% of the diameter). The excellent accuracy obtained in identifying position and depth of different cracks proves the effectiveness and reliability of the proposed method. Moreover, the implementation of identification method operates on a PC and takes short time to run, therefore is suitable for industrial applications.

scholarly journals Improving Landscape Spacious Development

2018 ◽  
Vol 7 (3.2) ◽  
pp. 463
Author(s):  
Vladyslav Tymoshevskyi ◽  
Ilona Yurko ◽  
Grigoriy Shariy
Keyword(s):  
Functional Relationship ◽  
Arable Land ◽  
Payback Period ◽  
Capital Expenditures ◽  
Geometrical Parameters ◽  
Triangular Form ◽  
Design Decisions ◽  
Land Protection ◽  
Different Types ◽  
Different Shapes

The purpose of research resulted in recommendations development for landscapes spatial and territory organization improvement, in particular, on the basis of fields geometric parameters influence analysis. The conducted researches are focused on ordering of arable land territory, having spatial and territory unfavorable conditions for management. Analysis is carried out and estimation of fields geometrical parameters influence on mechanized cultivation is provided. The scale for assessing feasibility of crop rotation separating triangular form fields into trapezoidal form workspaces was formed. Different forms triangular plots (rectangular, equilateral, isosceles, scalene) and areas (from 6 to 72 ha) are considered during the study. For a comprehensive analysis of design decisions, economic indicators were used, namely: capital expenditures, annual expenses, additional products cost. Power polynomials were used to establish trends and describe the functional relationship between the different shapes of land plots area and the annual profit, resulted expenses and payback period. They were described by equations and graphs were constructed. Unprofitable, ineffective, expedient and optimal division of the triangular different types areas into trapezoidal form workspaces are presented in the table. The obtained results can be used in land management projects development for territories spatial development, territory organization, rational use organization and land protection. 

Math is Beautiful

2015 ◽  
Vol 22 (2) ◽  
pp. 71-73 ◽  
Keyword(s):  
Public School ◽  
Third Grade ◽  
Second Grade ◽  
Stained Glass ◽  
Different Types ◽  
Different Shapes ◽  
Mathematics Class ◽  
Family Vacation

Two different solution contexts for the Math Is Beautiful investigation are described here: Ali Duncan's third-grade class at Prueter Public School in Kitchener, Ontario, solved the problem during a mathematics class; and Cynthia Hockman-Chupp's son in the second grade explored the investigation while on a plane trip during a family vacation. In both cases, students were asked to design a stained-glass window using specific criteria related to quadrilaterals. To meet the criteria, students had to consider how many shapes would fill a designated space, how different shapes can fit together to tile a surface, and the properties and attributes of different types of quadrilaterals.

Sign in / Sign up

Export Citation Format

Share Document