Stable and robust stretched-pulse mode-locked wavelength-swept laser for MHz OCT

2021 ◽  
Author(s):  
Jongyoon Joo ◽  
Tae Shik Kim ◽  
Benjamin J. Vakoc ◽  
Wang-Yuhl Oh
Keyword(s):  
Pulse Mode

Dynamic Changes of Collagen Ⅳ During Cancer Invasion and Migration: Pulse Mode

2013 ◽  
Vol 40 (10) ◽  
pp. 1056
Author(s):  
Min FANG ◽  
Jing-Ping YUAN ◽  
Chun-Wei PENG ◽  
Shao-Ping LIU ◽  
Yan LI
Keyword(s):  
Cancer Invasion ◽  
Pulse Mode ◽  
Dynamic Changes ◽  
Invasion And Migration ◽  
And Migration

scholarly journals Experimental studies on the possibility of using a pulsed laser for spot welding of thin metallic foils

2020 ◽  
Vol 10 (1) ◽  
pp. 674-680
Author(s):  
Piotr Sęk
Keyword(s):  
Experimental Studies ◽  
Pulsed Laser ◽  
Welding Process ◽  
Pulse Mode ◽  
Weld Strength ◽  
Spot Welds ◽  
Butt Welding ◽  
Strength Tests ◽  
Metallic Foils ◽  
The Impact

AbstractThe purpose of the experiment was to study the influence of the laser beam in pulse mode on metallic foils in order to obtain a spot weld. The welding process was carried out using the overlap weld method, using spot welds in various quantities. The Nd - YAG BLS 720 pulsed laser was used to conduct the experiment. The impact of the number of spot welds on the value of force needed to break the sample was examined. A number of measurements were carried out to determine the best process parameters. Butt welding and overlap welding were also performed using a continuous weld consisting of spot welds. Weld strength tests were performed to select the most appropriate parameters for the process under consideration.

scholarly journals Influence of Duty Ratio and Current Mode on Robot 316L Stainless Steel Arc Additive Manufacturing

Metals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 508
Author(s):  
Ping Yao ◽  
Hongyan Lin ◽  
Wei Wu ◽  
Heqing Tang
Keyword(s):  
Stainless Steel ◽  
Additive Manufacturing ◽  
Heat Input ◽  
Low Frequency ◽  
Single Pulse ◽  
Pulse Mode ◽  
Double Pulse ◽  
Duty Ratio ◽  
Utilization Rate ◽  
Specimen Height

Wire and arc additive manufacturing (WAAM) is usually for fabricating components due to its low equipment cost, high material utilization rate and cladding efficiency. However, its applications are limited by the large heat input decided by process parameters. Here, four 50-layer stainless steel parts with double-pulse and single-pulse metal inert gas (MIG) welding modes were deposited, and the effect of different duty ratios and current modes on morphology, microstructure, and performance was analyzed. The results demonstrate that the low frequency of the double-pulse had the effect of stirring the molten pool; therefore, the double-pulse mode parts presented a bigger width and smaller height, finer microstructure and better properties than the single-pulse mode. Furthermore, increasing the duty ratio from 35% to 65% enlarged the heat input, which then decreased the specimen height, increased the width, and decreased the hardness and the tensile strength.

scholarly journals Mind the gap – Part 1: Accurately locating warm marine boundary layer clouds and precipitation using spaceborne radars

2020 ◽  
Vol 13 (5) ◽  
pp. 2363-2379 ◽  
Author(s):  
Katia Lamer ◽  
Pavlos Kollias ◽  
Alessandro Battaglia ◽  
Simon Preval
Keyword(s):  
Boundary Layer ◽  
Cloud Cover ◽  
Marine Boundary Layer ◽  
Short Pulse ◽  
Pulse Mode ◽  
Cloud Base ◽  
Boundary Layer Clouds ◽  
Highly Sensitive ◽  
Eastern North Atlantic ◽  
Long Pulse

Abstract. Ground-based radar observations show that, over the eastern North Atlantic, 50 % of warm marine boundary layer (WMBL) hydrometeors occur below 1.2 km and have reflectivities of < −17 dBZ, thus making their detection from space susceptible to the extent of surface clutter and radar sensitivity. Surface clutter limits the ability of the CloudSat cloud profiling radar (CPR) to observe the true cloud base in ∼52 % of the cloudy columns it detects and true virga base in ∼80 %, meaning the CloudSat CPR often provides an incomplete view of even the clouds it does detect. Using forward simulations, we determine that a 250 m resolution radar would most accurately capture the boundaries of WMBL clouds and precipitation; that being said, because of sensitivity limitations, such a radar would suffer from cloud cover biases similar to those of the CloudSat CPR. Observations and forward simulations indicate that the CloudSat CPR fails to detect 29 %–43 % of the cloudy columns detected by ground-based sensors. Out of all configurations tested, the 7 dB more sensitive EarthCARE CPR performs best (only missing 9.0 % of cloudy columns) indicating that improving radar sensitivity is more important than decreasing the vertical extent of surface clutter for measuring cloud cover. However, because 50 % of WMBL systems are thinner than 400 m, they tend to be artificially stretched by long sensitive radar pulses, hence the EarthCARE CPR overestimation of cloud top height and hydrometeor fraction. Thus, it is recommended that the next generation of space-borne radars targeting WMBL science should operate interlaced pulse modes including both a highly sensitive long-pulse mode and a less sensitive but clutter-limiting short-pulse mode.

scholarly journals Modelling of an Electromagnetic Space Propulsion System for Pulse Mode Operation

2012 ◽  
Vol 38 ◽  
pp. 3691-3699
Author(s):  
S. Sarathkumar ◽  
K. Periyannaswamy ◽  
S. Thanigaiarasu
Keyword(s):  
Pulse Mode ◽  
Propulsion System ◽  
Space Propulsion ◽  
Mode Operation

scholarly journals Effects of Er:YAG Laser on Mineral Content of Sound Dentin in Primary Teeth

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
Cigdem Guler ◽  
Meral Arslan Malkoc ◽  
Veli Alper Gorgen ◽  
Erhan Dilber ◽  
Mehmet Bulbul
Keyword(s):  
Surface Roughness ◽  
Mineral Content ◽  
Primary Teeth ◽  
Er:Yag Laser ◽  
Short Pulse ◽  
Pulse Mode ◽  
Emission Spectrometry ◽  
Control Group ◽  
Group A ◽  
Group B

The aim of the present study was to evaluate the mineral content of sound dentin in primary teeth prepared using an Er:YAG laser at two different power settings. Thirty-six primary second molars were used in this study. Three dentin slabs were obtained from each tooth, and the slabs were randomly divided into three groups: Group A, control; Group B, Er:YAG laser at 3.5 W, 175 mJ, and 20 Hz, short pulse mode; and Group C, Er:YAG laser at 4 W, 200 mJ, and 20 Hz, medium-short pulse mode. One dentin slab per group was used to evaluate the dentinal morphology and surface roughness values using SEM and profilometer, respectively. Mineral content in the dentin slabs were calculated by inductively coupled plasma-atomic emission spectrometry (ICP-AES). The data were analyzed by one-way analysis of variance and Tukey’s HSD tests. No significant differences in Ca, K, Mg, Na, and P levels or Ca/P ratio were found among the groups(P>0.05). SEM micrographs showed that surface irregularities increased with a higher power setting. The surface roughness after laser treatment in Group B and Group C was found to be similar, unlike Group A.

65-femtosecond pulse generation from a synchronously pumped dye laser without a colliding-pulse mode-locking technique

1987 ◽  
Vol 12 (9) ◽  
pp. 681 ◽  
Author(s):  
Masataka Nakazawa ◽  
Takashi Nakashima ◽  
Hirokazu Kubota ◽  
Shigeyuki Seikai
Keyword(s):  
Femtosecond Pulse ◽  
Mode Locking ◽  
Pulse Mode ◽  
Pulse Generation ◽  
Dye Laser ◽  
Synchronously Pumped

Influence of Copper on the Switching Properties of Hafnium Oxide-Based Resistive Memory

2011 ◽  
Vol 1337 ◽  
Author(s):  
B.D. Briggs ◽  
S.M. Bishop ◽  
K.D. Leedy ◽  
B. Butcher ◽  
R. L. Moore ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Hafnium Oxide ◽  
Copper Concentration ◽  
Atomic Layer ◽  
Metal Electrode ◽  
Pulse Mode ◽  
Switching Behavior ◽  
Material Structure ◽  
Memory Devices ◽  
Resistive Memory

ABSTRACTHafnium oxide-based resistive memory devices have been fabricated on copper bottom electrodes. The HfOx active layers in these devices were deposited by atomic layer deposition at 250 °C with tetrakis(dimethylamido)hafnium(IV) as the metal precursor and an O2 plasma as the reactant. Depth profiles of the HfOx by x-ray photoelectron spectroscopy and secondary ion mass spectroscopy revealed a copper concentration on the order of five atomic percent throughout the HfOx film. This phenomenon has not been previously reported in resistive switching literature and therefore may have gone unnoticed by other investigators. The MIM structures fabricated from the HfOx exhibited non-polar behavior, independent of the top metal electrode (Ni, Pt, Al, Au). These results are analogous to the non-polar switching behavior observed by Yang et al. [2] for intentionally Cu-doped HfOx resistive memory devices. The distinguishing characteristic of the material structure produced in this research is that the copper concentration increases to 60 % in a conducting surface copper oxide layer ~20 nm thick. Lastly, the results from both sweep- and pulse-mode current-voltage measurements are presented and preliminary work on fabricating sub-100 nm devices is summarized.

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