Creation of the spatial metric for the image of an agricultural object

The analysis of various approaches to forecasting complex multifactorial systems in conditions of uncertainty of external conditions is presented. It is necessary to develop these approaches in order to create adequate models of agricultural activities for their effective planning and management. A distinctive feature of agricultural production is a critical dependence on environmental factors, which cannot be accurately predicted. Regression modeling and analysis of time series used at present to solve this problem in difficult cases do not result in an adequate forecast of the dynamics of an agricultural object. As an approach, it is proposed to use the construction of the "image" of the system. This approach is classified as "nature-like", as it simulates a way of decision-making by a specialist on the basis of accumulated experience and intuition. The key parameter of this construction will be the correct choice of the metric (coordinate system). This approach is illustrated by an example of creating an image of a two-dimensional phenomenon in a one-dimensional coordinate system. As a result, an image is understood as an image of reality in a vector space of a certain dimension. The image in the authors' view is a reflection of reality in an artificially created metric, more suitable for understanding and analysis, but retaining the main (important) features and functions of the original object. Artificial intelligence techniques can be seen as tools for image creation and analysis. An important characteristic of an image is its predictive power, i.e. the ability to use the image in order to predict the state of a real object in the future period. An image retains its predictive power if the forecast obtained using this image corresponds to the data obtained when observing a real object. The image is formed in a suitable metric for solving a specific problem. The key metric parameter of the image of agricultural activity, suitable for forecasting purposes, is the minimum dimension of the vector space used, at which the predictive power of the image is retained to solve the problem.

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Generalized Modeling of Milling Mechanics and Dynamics: Part II — Inserted Cutters

10.1115/imece1999-0692 ◽

1999 ◽

Author(s):

Serafettin Engin ◽

Yusuf Altintas

Keyword(s):

Coordinate System ◽

Thickness Distribution ◽

Local Coordinate System ◽

Chip Thickness ◽

Milling Process ◽

Global Coordinate System ◽

Edge Point ◽

Modeling And Analysis ◽

Cutting Zone ◽

Body Center

Abstract Inserted cutters are widely used in roughing and finishing of parts. The insert geometry and distribution of inserts on the cutter body vary significantly in industry depending on the application. This paper presents a generalized mathematical model of inserted cutters for the purpose of predicting cutting forces, vibrations, dimensional surface finish and stability lobes in milling. In this paper, the edge geometry is defined in the local coordinate system of each insert, and placed and oriented on the cutter body using cutter’s global coordinate system. The cutting edge locations are defined mathematically, and used in predicting the chip thickness distribution along the cutting zone. Each insert may have a different geometry, such as rectangular, convex triangular or a mathematically definable edge. Each insert can be placed on the cutter body mathematically by providing the coordinates of insert center with respect to the cutter body center. The inserts can be oriented by rotating them around the cutter body, thus each insert may be assigned to have different lead and axial rake angles. By solving the mechanics and dynamics of cutting at each edge point, and integrating them over the contact zone, it is shown that the milling process can be predicted for any inserted cutter. A sample of inserted cutter modeling and analysis examples are provided with experimental verifications.

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Implementation of Mathematical Modeling for Wire Rope Strands

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.608-609.1769 ◽

2012 ◽

Vol 608-609 ◽

pp. 1769-1772

Author(s):

Xiao Yu Wang ◽

Xiang Bao Meng ◽

Ji Xin Wang ◽

Ke Gao

Keyword(s):

Mathematical Modeling ◽

Coordinate System ◽

Local Coordinate System ◽

Wire Rope ◽

Parametric Modeling ◽

Helical Structures ◽

Element Analysis ◽

Modeling And Analysis ◽

Analysis Application ◽

Mechanical Performances

Modeling for complex spiral wire rope structures, on which the mechanical performances largely depend, are paramount to finite element analysis application. Three mathematical modeling thoughts were brought out to create the geometric models of wire rope strands. The first one was presented based on the centerline times of the helical structures, as the centerline times can be decreased through transitional coordinate system. For the second, the centerlines of the wire rope were formed by the helical movement of predefined point. In the third one, a local coordinate system which can be transformed into the world coordinate system by their relationship was employed. The above three ideas were implemented by different kinds of derivation. The geometric parameter equations were presented to express the accurate wire rope models. These approaches are beneficial for parametric modeling and analysis of wire rope strands.

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Dynamic Analysis of a 3-RRR Parallel Robot With Joint Clearances Using Natural Coordinates

Volume 5B: 38th Mechanisms and Robotics Conference ◽

10.1115/detc2014-34609 ◽

2014 ◽

Cited By ~ 2

Author(s):

Xuchong Zhang ◽

Xianmin Zhang

Keyword(s):

Coordinate System ◽

Parallel Robot ◽

Force Model ◽

Modeling And Analysis ◽

Clearance Joints ◽

Continuous Contact ◽

Coulomb’S Friction ◽

Contact Points ◽

Joint Clearances ◽

Natural Coordinate

A general computational methodology for modeling and analysis of planar rigid multibody systems with multi clearance joints is presented. The contact points are important for contact detection, natural coordinate system is implemented to describe the rigid links in order to reduce the amount of calculation. The Lankarani-Nikravesh continuous contact-impact model is used to evaluate the contact force, in which energy dissipation in the form of hysteresis damping is considered. The improved Coulomb’s friction force model is used to describe the friction phenomenon between the joint components. Numerical results for 3-RRR mechanism with revolute clearance joints are presented and discussed. This methodology is further compared with the widely used reference coordinate system, the numerical simulation results show that the presented method is an effective and new method to predict the dynamic characteristics of planar mechanical systems with clearance joints.

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Predictive Power of Peer Behavioral Assessment for Subsequent Maladjustment in Community Samples of Disruptive and Nondisruptive Children

Journal of Child Psychology and Psychiatry ◽

10.1017/s0021963099005181 ◽

2000 ◽

Vol 41 (2) ◽

pp. 181-190 ◽

Cited By ~ 8

Author(s):

George M. Realmuto ◽

Gerald J. August ◽

Joel M. Hektner

Keyword(s):

Predictive Power ◽

Behavioral Assessment

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Reference Coordinate System Requirements for Geophysics

International Astronomical Union Colloquium ◽

10.1017/s0252921100050946 ◽

1975 ◽

Vol 26 ◽

pp. 87-92

Author(s):

P. L. Bender

Keyword(s):

Coordinate System ◽

Polar Motion ◽

Main Part ◽

Measurement Techniques ◽

Reference Points ◽

Angular Motion ◽

Coordinate Systems ◽

Axis Of Rotation ◽

The Earth ◽

Fixed System

AbstractFive important geodynamical quantities which are closely linked are: 1) motions of points on the Earth’s surface; 2)polar motion; 3) changes in UT1-UTC; 4) nutation; and 5) motion of the geocenter. For each of these we expect to achieve measurements in the near future which have an accuracy of 1 to 3 cm or 0.3 to 1 milliarcsec.From a metrological point of view, one can say simply: “Measure each quantity against whichever coordinate system you can make the most accurate measurements with respect to”. I believe that this statement should serve as a guiding principle for the recommendations of the colloquium. However, it also is important that the coordinate systems help to provide a clear separation between the different phenomena of interest, and correspond closely to the conceptual definitions in terms of which geophysicists think about the phenomena.In any discussion of angular motion in space, both a “body-fixed” system and a “space-fixed” system are used. Some relevant types of coordinate systems, reference directions, or reference points which have been considered are: 1) celestial systems based on optical star catalogs, distant galaxies, radio source catalogs, or the Moon and inner planets; 2) the Earth’s axis of rotation, which defines a line through the Earth as well as a celestial reference direction; 3) the geocenter; and 4) “quasi-Earth-fixed” coordinate systems.When a geophysicists discusses UT1 and polar motion, he usually is thinking of the angular motion of the main part of the mantle with respect to an inertial frame and to the direction of the spin axis. Since the velocities of relative motion in most of the mantle are expectd to be extremely small, even if “substantial” deep convection is occurring, the conceptual “quasi-Earth-fixed” reference frame seems well defined. Methods for realizing a close approximation to this frame fortunately exist. Hopefully, this colloquium will recommend procedures for establishing and maintaining such a system for use in geodynamics. Motion of points on the Earth’s surface and of the geocenter can be measured against such a system with the full accuracy of the new techniques.The situation with respect to celestial reference frames is different. The various measurement techniques give changes in the orientation of the Earth, relative to different systems, so that we would like to know the relative motions of the systems in order to compare the results. However, there does not appear to be a need for defining any new system. Subjective figures of merit for the various system dependon both the accuracy with which measurements can be made against them and the degree to which they can be related to inertial systems.The main coordinate system requirement related to the 5 geodynamic quantities discussed in this talk is thus for the establishment and maintenance of a “quasi-Earth-fixed” coordinate system which closely approximates the motion of the main part of the mantle. Changes in the orientation of this system with respect to the various celestial systems can be determined by both the new and the conventional techniques, provided that some knowledge of changes in the local vertical is available. Changes in the axis of rotation and in the geocenter with respect to this system also can be obtained, as well as measurements of nutation.

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2.2. Working Group 2: Conceptual Definitions of Reference Coordinate Systems for Earth Dynamics

International Astronomical Union Colloquium ◽

10.1017/s0252921100050867 ◽

1975 ◽

Vol 26 ◽

pp. 21-26

Keyword(s):

Coordinate System ◽

Working Group ◽

General Character ◽

Coordinate Systems ◽

Reference Coordinate System ◽

Group 2 ◽

Definition Of ◽

Earth Dynamics

An ideal definition of a reference coordinate system should meet the following general requirements:1. It should be as conceptually simple as possible, so its philosophy is well understood by the users.2. It should imply as few physical assumptions as possible. Wherever they are necessary, such assumptions should be of a very general character and, in particular, they should not be dependent upon astronomical and geophysical detailed theories.3. It should suggest a materialization that is dynamically stable and is accessible to observations with the required accuracy.

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