scholarly journals Displacements Study of an Earth Fill Dam Based on High Precision Geodetic Monitoring and Numerical Modeling

Sensors ◽  
2018 ◽  
Vol 18 (5) ◽  
pp. 1369 ◽  
Author(s):  
Luis Acosta ◽  
M. de Lacy ◽  
M. Ramos ◽  
Juan Cano ◽  
Antonio Herrera ◽  
...  
Keyword(s):  
Numerical Modeling ◽  
High Precision ◽  
Earth Fill

NUMERICAL MODELING OF UNDERWATER EXPLOSION PROPERTIES FOR NONIDEAL EXPLOSIVES

2008 ◽  
Vol 22 (09n11) ◽  
pp. 1618-1625 ◽  
Author(s):  
JAIMIN LEE
Keyword(s):  
Numerical Modeling ◽  
High Precision ◽  
Underwater Explosion ◽  
Reaction Rates ◽  
Experimental Results ◽  
Good Agreement

Underwater experiments for an ideal explosive, TNT, and two nonideal explosives, CETR emulsion and DXD-04, were performed, and numerically simulated. For TNT, calculations done by using program-burn models based on the rate-independent Chapman-Jouguet theory were in a good agreement with experimental results, which validated the wide use of program-burn models for ideal explosives. For CETR emulsion and DXD-04, experimental observations could be reproduced with high precision only when reaction rates were employed. These results demonstrated that detonation in nonideal explosives can be modeled only by using properly calibrated reaction rates.

scholarly journals SYNTHESIS METHOD OF SYSTEMS FOR HIGH-PRECISION MOVEMENTS CONTROL OF UNDERWATER MANIPULATORS

2020 ◽  
pp. 31-37
Author(s):  
В.Ф. Филаретов ◽  
А.Ю. Коноплин ◽  
А.В. Зуев ◽  
Н.А. Красавин
Keyword(s):  
Numerical Modeling ◽  
High Precision ◽  
Dynamic Models ◽  
Dynamic Properties ◽  
Synthesis Method ◽  
Analytical Calculation ◽  
Viscous Friction ◽  
Viscous Medium ◽  
Inverse Dynamic ◽  
Electric Drives

Представлена разработка метода синтеза комбинированных систем, обеспечивающих высокоточное управление перемещениями рабочих органов многозвенных манипуляторов, установленных на подводных аппаратах. Предложенный метод позволяет точно идентифицировать негативные моментные воздействия на выходные валы электроприводов манипуляторов, возникающие при их перемещениях в вязкой среде, а также моменты сухого и вязкого трений в этих приводах. При использовании этого метода вначале с помощью рекуррентного алгоритма решения обратной задачи динамики выполняется предварительный аналитический расчет внешних моментов, возникающих во всех степенях подвижности движущегося подводного манипулятора. Этот расчет является весьма приближенным вследствие сложности определения параметров реального взаимодействия с водной средой всех звеньев манипулятора и захваченного груза. Поэтому далее с использованием динамических моделей электроприводов каждой степени подвижности, включающих аналитически рассчитанные внешние моменты, строятся дополнительные диагностические наблюдатели. Эти наблюдатели с помощью формируемых ими невязок точнее определяют величины непредвиденных изменений моментов вязкого и сухого трения в самих электроприводах. Затем идентифицированные моментные воздействия на электроприводы всех степеней подвижности манипулятора точно компенсируются с помощью самонастраивающихся корректирующих устройств, обеспечивающих стабилизацию динамических свойств этих приводов на номинальном уровне. Выполнено численное моделирование системы, синтезированной с помощью разработанного метода для многозвенного манипулятора с кинематической схемой PUMA, рабочий орган которого перемещался по сложным пространственным траекториям. Результаты численного моделирования показали многократное повышение точности выполнения подводными манипуляторами различных технологических операций при использовании синтезированной системы. The paper presents a synthesis method of combined systems providing high-precision movements control of multilink manipulator arm tool mounted on underwater vehicles. The proposed method allows precise identification of negative torques on the output shaft of the manipulator electric drives that emerged during its motion in a viscous medium and moments of coulomb and viscous friction in these drives. This method begins with a preliminary analytical calculation of external moments appearing in underwater manipulator axes of motion by the recurrent algorithm of solving the inverse dynamic problem. This calculation is highly coarse due to the complexity of determining parameters of the real interaction between all links of the manipulator, engaged load, and seawater medium. Additional diagnostic observers are then synthesized using dynamic models of electric drives of every axis of freedom, including analytically determined external moments. These observers can more precisely determine the values of unpredicted changes of the viscous and coulomb friction moments in drives itself using formed discrepancy signals. Then identified torques on the electric drives of all manipulator axes are compensated using self-regulated correcting devices capable of stabilizing these drives' dynamic properties on the nominal level. The paper contains numerical modeling of the system synthesized by a developed method for a multilink manipulator with a PUMA kinematic scheme, an arm tool of which was moved alongside a complex three-dimensional trajectory. The numerical modeling results showed a significant increase in the accuracy of different technological operations performed by underwater manipulators using a synthesized system.

Hybrid Special Finite Element Method for Bi-Material Crack

2006 ◽  
Vol 312 ◽  
pp. 95-104
Author(s):  
Chun Hui Yang ◽  
Y.X. Zhang ◽  
Hoon Huh
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Numerical Modeling ◽  
Finite Elements ◽  
High Precision ◽  
Edge Crack ◽  
Interfacial Crack ◽  
Fracture Analysis ◽  
Numerical Examples ◽  
Hybrid Element

In the paper, two novel 2-D hybrid special finite elements each containing an interfacial edge crack, which lies along or vertical to the interface between two materials, are developed. These proposed elements can assure the high precision especially in the vicinity of crack tip and provide a better description of its singularity with only one hybrid element surrounding one interfacial crack, thus, the numerical modeling of fracture analysis on bi-material crack can be greatly simplified. Numerical examples are provided to demonstrate the validity and versatility of the proposed method.

Numerical modeling of composite support for high-precision equipment

2018 ◽  
Author(s):  
Sergey Chernyakin ◽  
Sergey Perov ◽  
Yurii Skvortsov
Keyword(s):  
Numerical Modeling ◽  
High Precision ◽  
Composite Support ◽  
Precision Equipment

Automatic measurement of SAED patterns from asbestos minerals

1988 ◽  
Vol 46 ◽  
pp. 846-847
Author(s):  
J. C. Russ ◽  
T. Taguchi ◽  
P. M. Peters ◽  
E. Chatfield ◽  
J. C. Russ ◽  
...  
Keyword(s):  
Diffraction Pattern ◽  
High Precision ◽  
Diffraction Data ◽  
Automatic Measurement ◽  
Automatic Method ◽  
Important Method ◽  
X Ray ◽  
Integrated Intensity ◽  
Asbestiform Minerals ◽  
True Center

Conventional SAD patterns as obtained in the TEM present difficulties for identification of materials such as asbestiform minerals, although diffraction data is considered to be an important method for making this purpose. The preferred orientation of the fibers and the spotty patterns that are obtained do not readily lend themselves to measurement of the integrated intensity values for each d-spacing, and even the d-spacings may be hard to determine precisely because the true center location for the broken rings requires estimation. We have implemented an automatic method for diffraction pattern measurement to overcome these problems. It automatically locates the center of patterns with high precision, measures the radius of each ring of spots in the pattern, and integrates the density of spots in that ring. The resulting spectrum of intensity vs. radius is then used just as a conventional X-ray diffractometer scan would be, to locate peaks and produce a list of d,I values suitable for search/match comparison to known or expected phases.

On effects of non-systematic reflections on weak-beam images of partial dislocations

1991 ◽  
Vol 49 ◽  
pp. 688-689
Author(s):  
K. Z. Botros ◽  
S. S. Sheinin
Keyword(s):  
High Precision ◽  
Stacking Fault ◽  
Important Application ◽  
Stacking Fault Energy ◽  
Sharp Peak ◽  
Weak Beam ◽  
Partial Dislocations ◽  
Deviation Parameter ◽  
Beam Diffraction

The main features of weak beam images of dislocations were first described by Cockayne et al. using calculations of intensity profiles based on the kinematical and two beam dynamical theories. The feature of weak beam images which is of particular interest in this investigation is that intensity profiles exhibit a sharp peak located at a position very close to the position of the dislocation in the crystal. This property of weak beam images of dislocations has an important application in the determination of stacking fault energy of crystals. This can easily be done since the separation of the partial dislocations bounding a stacking fault ribbon can be measured with high precision, assuming of course that the weak beam relationship between the positions of the image and the dislocation is valid. In order to carry out measurements such as these in practice the specimen must be tilted to "good" weak beam diffraction conditions, which implies utilizing high values of the deviation parameter Sg.

Digital differential hysteresis iimage processing displays what the microscope acquires but the eye can't see

1995 ◽  
Vol 53 ◽  
pp. 642-643
Author(s):  
Klaus-Ruediger Peters
Keyword(s):  
Image Processing ◽  
Visual System ◽  
High Precision ◽  
Image Data ◽  
Processing Technology ◽  
Output Data ◽  
Contrast Resolution ◽  
Pixel Intensity ◽  
Data Reading ◽  
Hysteresis Properties

Differential hysteresis processing is a new image processing technology that provides a tool for the display of image data information at any level of differential contrast resolution. This includes the maximum contrast resolution of the acquisition system which may be 1,000-times higher than that of the visual system (16 bit versus 6 bit). All microscopes acquire high precision contrasts at a level of <0.01-25% of the acquisition range in 16-bit - 8-bit data, but these contrasts are mostly invisible or only partially visible even in conventionally enhanced images. The processing principle of the differential hysteresis tool is based on hysteresis properties of intensity variations within an image.Differential hysteresis image processing moves a cursor of selected intensity range (hysteresis range) along lines through the image data reading each successive pixel intensity. The midpoint of the cursor provides the output data. If the intensity value of the following pixel falls outside of the actual cursor endpoint values, then the cursor follows the data either with its top or with its bottom, but if the pixels' intensity value falls within the cursor range, then the cursor maintains its intensity value.

High precision measurement of the SOS surface thickness in the rough phase

1991 ◽  
Vol 1 (12) ◽  
pp. 1669-1673 ◽  
Author(s):  
Hans Gerd Evertz ◽  
Martin Hasenbusch ◽  
Mihail Marcu ◽  
Klaus Pinn ◽  
Sorin Solomon
Keyword(s):  
High Precision ◽  
Precision Measurement ◽  
High Precision Measurement ◽  
Surface Thickness
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