Modeling three-dimensional transmission of a NOLM in continuous-wave and pulsed regimes for optical communications

2019 ◽  
Author(s):  
José D. Filoteo Razo ◽  
Juan C. Hernández-García ◽  
Julián M. Estudillo-Ayala ◽  
Olivier J. M. Pottiez ◽  
Jesus P. Lauterio-Cruz ◽  
...  
Keyword(s):  
Optical Communications ◽  
Continuous Wave ◽  
Three Dimensional

Transient Elastic Thermal Stress Development During Laser Scribing of Ceramics

2000 ◽  
Vol 123 (1) ◽  
pp. 171-177 ◽  
Author(s):  
Michael F. Modest ◽  
Thomas M. Mallison
Keyword(s):  
Thermal Stresses ◽  
Continuous Wave ◽  
Elastic Stress ◽  
Three Dimensional ◽  
Thick Layer ◽  
Temperature Fields ◽  
Subsurface Cracks ◽  
Laser Scribing ◽  
Micro Cracks ◽  
Cutting Speeds

Lsaers are emerging as a valuable tool for shaping and cutting hard and brittle ceramics. Unfortunately, the large, concentrated heat flux rates that allow the laser to efficiently cut and shape the ceramic also result in large localized thermal stresses in a small heat-affected zone. These notable thermal stresses can lead to micro-cracks, a decrease in strength and fatigue life, and possibly catastrophic failure. In order to assess where, when, and what stresses occur during laser scribing, an elastic stress model has been incorporated into a three-dimensional scribing and cutting code. First, the code predicts the temporal temperature fields and the receding surface of the ceramic. Then, using the scribed geometry and temperature field, the elastic stress fields are calculated as they develop and decay during the laser scribing process. The analysis allows the prediction of stresses during continuous wave and pulsed laser operation, a variety of cutting speeds and directions, and various shapes and types of ceramic material. The results of the analysis show substantial tensile stresses develop over a thick layer below and parallel to the surface, which may be the cause of experimentally observed subsurface cracks.

scholarly journals Three-dimensional Sonography in the Assessment of Normal Fetal Anatomy in Late Pregnancy

2010 ◽  
Vol 4 (3) ◽  
pp. 217-231
Author(s):  
Badreldeen Ahmed ◽  
Ulrich Honemeyer
Keyword(s):  
Continuous Wave ◽  
Power Doppler ◽  
Three Dimensional ◽  
Late Pregnancy ◽  
Research Field ◽  
Surface Rendering ◽  
Volume Data ◽  
Data Set ◽  
3D Volume ◽  
Color And Power Doppler

Abstract Three-dimensional, multiplanar sonography, using a volume data set acquired with a 3D probe, has revolutionized ultrasonographic imaging and takes sonographers to a new perception of the fetus in 3 dimensions. Real time scanning, until the late nineties only possible in B-mode, can now be performed in 3D with up to 40 frames/sec. Fetal neurology emerged as a new perinatal research field with the 4D visualization of fetal behavior. Doppler ultrasound, diversified and refined from continuous wave and pulsed Doppler to Color – and Power Doppler, when added to 3D sonography, creates fascinating options of noninvasive fetal vascular mapping (sonoangiography) and vascular assessment of placenta. The diagnostic and demonstrative potential of an acquired 3D volume data set can be maxed with the help of postprocessing and rendering software. After storage, the evaluation of fetal 3D data sets can happen without the patient, with the option of specialist consultation, using telemedicine. In the article, the new 3D “modes” like surface rendering, maximum mode, 3D Color and Power Doppler, STIC, volume rendering, and glass body rendering, are described and illustrated in their display of normal fetal anatomy.

Design, experiment and adsorption mechanism analysis of bionic sucker based on octopus sucker

2019 ◽  
Vol 233 (12) ◽  
pp. 1250-1261
Author(s):  
Peng Xi ◽  
Qian Cong ◽  
Jin Xu ◽  
Kun Qiu
Keyword(s):  
Surface Morphology ◽  
Continuous Wave ◽  
Three Dimensional ◽  
Tensile Tests ◽  
Mechanism Analysis ◽  
Three Dimensional Printing ◽  
Adsorption Performance ◽  
Before And After ◽  
Sealing Mechanism ◽  
Microscopic Morphology

The vacuum chuck is widely used in industrial and daily life. By observing the macroscopic and microscopic morphology of octopus sucker, it is found that the sucker surface has concave–convex continuous wave shape with large number of non-smooth morphologies. The sealing mechanism of octopus sucker is analyzed according to its surface morphology before and after adsorption, and the non-smooth morphology is found to greatly enhance the adsorption. Based on the bionics theory, the non-smooth surface morphology of octopus sucker is applied to improve the sucker adsorption. And the bionic suckers with three types of grooves are designed. According to the model of standard and bionic suckers, the sucker entities are obtained by the method of three-dimensional printing and casting. And the tensile tests of suckers are carried out. The stress of suckers is analyzed by finite element method, and the sealing mechanism is discussed. According to the test results, the bionic sucker has larger adsorption force. And the ring sucker possesses the best adsorption performance. Compared with the standard sucker, the maximum adsorption force of the bionic sucker is increased by 12.2% in the air and 25.2% underwater. The adsorption force of bionic sucker becomes larger with the increase in the groove number; when the groove number increases to a certain extent, the adsorption force becomes smaller. The deformation of non-smooth morphology during adsorption makes the bionic sucker have a larger contact area. That is the reason why the bionic sucker has good adsorption performance. The bionic design of sucker can provide a new method to improve its adsorption.

Three-Dimensional Modeling of Selective Laser Sintering of Two-Component Metal Powder Layers

2005 ◽  
Vol 128 (1) ◽  
pp. 299-306 ◽  
Author(s):  
Tiebing Chen ◽  
Yuwen Zhang
Keyword(s):  
Metal Powder ◽  
Continuous Wave ◽  
Selective Laser Sintering ◽  
Three Dimensional ◽  
Laser Sintering ◽  
Powder Layer ◽  
Metal Powders ◽  
Gaussian Laser Beam ◽  
Scanning Velocity ◽  
Three Dimensional Modeling

Laser sintering of a metal powder mixture that contains two kinds of metal powders with significantly different melting points under a moving Gaussian laser beam is investigated numerically. The continuous-wave laser-induced melting accompanied by shrinkage and resolidification of the metal powder layer are modeled using a temperature-transforming model. The liquid flow of the melted low-melting-point metal driven by capillary and gravity forces is also included in the physical model. The numerical results are validated by experimental results, and a detailed parametric study is performed. The effects of the moving heat source intensity, the scanning velocity, and the thickness of the powder layer on the sintering depth, the configuration of the heat affected zone, and the temperature distribution are discussed.

scholarly journals Ground-penetrating radar-based underground environmental perception radar for robotic system

2020 ◽  
Vol 17 (2) ◽  
pp. 172988142092164
Author(s):  
Yuxuan Wu ◽  
Feng Shen ◽  
Dingjie Xu
Keyword(s):  
Antenna Array ◽  
Ground Penetrating Radar ◽  
Continuous Wave ◽  
Three Dimensional ◽  
Radar System ◽  
Environmental Perception ◽  
Robotic System ◽  
Three Dimensional Imaging ◽  
Wave Methods ◽  
Ground Penetrating

In recent years, the environmental perception technology for robotic system has attracted a lot of attention from researchers, but only a little of studies on environmental perception technology are focused on the space underground. Meanwhile, in the field of mobile robotic systems, with the development of research on underground emergency hedging and buried targets’ high-resolution fault imaging, more and more attention has also been paid to underground environmental detection and perception. This article proposes a ground-penetrating radar-based underground environmental perception radar (UEPR) for mobile robotic system indoors. The underground environmental perception radar can achieve noncontact and real-time perception, which helps people detect buried targets and get the image of targets more conveniently and precisely. Major contributions of this work are threefold. Firstly, a stepped frequency continuous wave modulation and demodulation scheme is proposed; secondly, a switch device for a six-channel antenna array is designed and contributed; thirdly, based on a linear antenna array and a signal processing platform, the underground environmental perception radar is supposed to achieve three-dimensional imaging in underground space indoors with its low power consumption. For the experiment of three-dimensional imaging on the copper box and underground environment indoors, the process of imaging is successful, although the size of them is a little bigger than the real size. In addition, the comparison experiment shows that the resolution of underground environmental perception radar system is similar with that of sound wave methods, and the working range of underground environmental perception radar system is deeper than the others. It can be concluded that the underground environmental perception radar can detect the copper box underground and perceive something special within 1.5 m depth.

scholarly journals Three-Dimensional Terahertz Continuous Wave Imaging Radar for Nondestructive Testing

IEEE Access ◽  
2020 ◽  
Vol 8 ◽  
pp. 144259-144276
Author(s):  
Xiaoxuan Zhang ◽  
Tianying Chang ◽  
Zhongmin Wang ◽  
Hong-Liang Cui
Keyword(s):  
Nondestructive Testing ◽  
Continuous Wave ◽  
Three Dimensional ◽  
Imaging Radar ◽  
Wave Imaging

Transient Elastic Stress Development During Laser Scribing of Ceramics

1999 ◽  
Author(s):  
Thomas M. Mallison ◽  
Michael F. Modest
Keyword(s):  
Thermal Stresses ◽  
Continuous Wave ◽  
Elastic Stress ◽  
Three Dimensional ◽  
Thick Layer ◽  
Temperature Fields ◽  
Subsurface Cracks ◽  
Laser Scribing ◽  
Micro Cracks ◽  
Cutting Speeds

Abstract Lasers are emerging as a valuable tool for shaping and cutting hard and brittle ceramics. Unfortunately, the large, concentrated heat flux rates that allow the laser to efficiently cut and shape the ceramic also result in large localized thermal stresses in a small heat-affected zone. These notable thermal stresses can lead to micro-cracks, a decrease in strength and fatigue life, and possibly catastrophic failure. In order to assess where, when, and what stresses occur during laser scribing, an elastic stress model has been incorporated into a three-dimensional scribing and cutting code. First, the code predicts the temporal temperature fields and the receding surface of the ceramic. Then, using the scribed geometry and temperature field, the elastic stress fields are calculated as they develop and decay during the laser scribing process. The analysis allows the prediction of stresses during continuous wave and pulsed laser operation, a variety of cutting speeds and directions, and various shapes and types of ceramic material. The results of the analysis show substantial tensile stresses develop over a thick layer below and parallel to the surface, which may be the cause of experimentally observed subsurface cracks.

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