scholarly journals Rotating network jets in the quiet Sun as observed by IRIS

2018 ◽  
Vol 616 ◽  
pp. A99 ◽  
Author(s):  
P. Kayshap ◽  
K. Murawski ◽  
A. K. Srivastava ◽  
B. N. Dwivedi
Keyword(s):  
Statistical Analysis ◽  
Rotational Motion ◽  
High Speed ◽  
Rotational Velocity ◽  
Spectral Lines ◽  
The Other ◽  
Secondary Component ◽  
Doppler Velocity ◽  
Quiet Sun ◽  
Resolution Imaging

Aims. We perform a detailed observational analysis of network jets to understand their kinematics, rotational motion, and underlying triggering mechanism(s). We analyzed the quiet-Sun (QS) data. Methods. IRIS high-resolution imaging and spectral observations (slit-jaw images: Si IV 1400.0 Å; raster: Si IV 1393.75 Å) were used to analyze the omnipresent rotating network jets in the transition region (TR). In addition, we also used observations from the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamic Observation (SDO). Results. The statistical analysis of 51 network jets is performed to understand their various mean properties, e.g., apparent speed (140.16 ± 39.41 km s−1), length (3.16 ± 1.18 Mm), and lifetimes (105.49 ± 51.75 s). The Si IV 1393.75 Å line has a secondary component along with its main Gaussian, which is formed due to the high-speed plasma flows (i.e., network jets). The variation in Doppler velocity across these jets (i.e., blueshift on one edge and redshift on the other) signify the presence of inherited rotational motion. The statistical analysis predicts that the mean rotational velocity (i.e., ΔV) is 49.56 km s−1. The network jets have high-angular velocity in comparison to the other class of solar jets. Conclusions. The signature of network jets is inherited in TR spectral lines in terms of the secondary component of the Si IV 1393.75 Å line. The rotational motion of network jets is omnipresent, which is reported first for this class of jet-like features. The magnetic reconnection seems to be the most favorable mechanism for the formation of these network jets.

scholarly journals Oscillatory phenomena in a solar network region

2008 ◽  
Vol 4 (S257) ◽  
pp. 181-184
Author(s):  
Georgia Tsiropoula ◽  
Kostas Tziotziou ◽  
Pavol Schwartz ◽  
Petr Heinzel
Keyword(s):  
Transition Region ◽  
Temporal Variations ◽  
Spectral Lines ◽  
The Other ◽  
Propagation Characteristics ◽  
Heliospheric Observatory ◽  
Quiet Sun ◽  
Network Region ◽  
Multi Wavelength

AbstractWe examine oscillatory phenomena in a solar network region from multi-wavelength, observations obtained by the ground-based Dutch Open Telescope (DOT), and by instruments on the spacecraft Solar and Heliospheric Observatory (SoHO). The observations were obtained during a coordinated observing campaign on October 14, 2005. The temporal variations of the intensities and velocities in two distinct regions of the quiet Sun were investigated: one containing several dark mottles and the other several bright points defining the network boundaries (NB). The aim is to find similarities and/or differences in the oscillatory phenomena observed in these two regions and in different spectral lines formed from the chromosphere to the transition region, as well as propagation characteristics of waves.

scholarly journals Leader-chasing behavior in negative artificial triggered lightning flashes

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Fukun Wang ◽  
Jianguo Wang ◽  
Li Cai ◽  
Rui Su ◽  
Wenhan Ding ◽  
...  
Keyword(s):  
High Speed ◽  
The Other ◽  
Lightning Flash ◽  
High Speed Camera ◽  
Return Stroke ◽  
Catching Up ◽  
Special Cases ◽  
Triggered Lightning

AbstractTwo special cases of dart leader propagation were observed by the high-speed camera in the leader/return stroke sequences of a classical triggered lightning flash and an altitude-triggered lightning flash, respectively. Different from most of the subsequent return strokes preceded by only one leader, the return stroke in each case was preceded by two leaders occurring successively and competing in the same channel, which herein is named leader-chasing behavior. In one case, the polarity of the latter leader was opposite to that of the former leader and these two combined together to form a new leader, which shared the same polarity with the former leader. In the other case, the latter leader shared the same polarity with the former leader and disappeared after catching up with the former leader. The propagation of the former leader in this case seems not to be significantly influenced by the existence of the latter leader.

scholarly journals Proposal of an Adaptive Neurofuzzy System to Control Flow Power in Distributed Generation Systems

Complexity ◽  
2019 ◽  
Vol 2019 ◽  
pp. 1-16 ◽  
Author(s):  
Helbert Eduardo Espitia ◽  
Iván Machón-González ◽  
Hilario López-García ◽  
Guzmán Díaz
Keyword(s):  
Statistical Analysis ◽  
Distributed Generation ◽  
Distribution System ◽  
Voltage Control ◽  
Control Flow ◽  
The Other ◽  
Charge Variation ◽  
Flow Power ◽  
Dynamics Identification ◽  
Neurofuzzy Systems

Systems of distributed generation have shown to be a remarkable alternative to a rational use of energy. Nevertheless, the proper functioning of them still manifests a range of challenges, including both the adequate energy dispatch depending on the variability of consumption and the interaction between generators. This paper describes the implementation of an adaptive neurofuzzy system for voltage control, regarding the changes observed in the consumption within the distribution system. The proposed design employs two neurofuzzy systems, one for the plant dynamics identification and the other for control purposes. This focus optimizes the controller using the model achieved through the identification of the plant, whose changes are produced by charge variation; consequently, this process is adaptively performed. The results show the performance of the adaptive neurofuzzy system via statistical analysis.

Was This in Your Statistics Textbook? IV. Frequency Data

1989 ◽  
Vol 25 (1) ◽  
pp. 11-25
Author(s):  
D. J. Finney
Keyword(s):  
Statistical Analysis ◽  
Contingency Tables ◽  
The Other ◽  
Frequency Data ◽  
Significance Tests ◽  
Test Statistic ◽  
Jumping To Conclusions ◽  
Proper Role ◽  
Measure Of Association

SUMMARYObservations that are frequencies rather than measurements often call for special types of statistical analysis. This paper comments on circumstances in which methods for one type of data can sensibly be used for the other. A section on two-way contingency tables emphasizes the proper role of χ2 a test statistic but not a measure of association; it mentions the distinction between one-tail and two-tail significance tests and reminds the reader of dangers. Multiway tables bring new complications, and the problems of interactions when additional classificatory factors are explicit or hidden are discussed at some length. A brief outline attempts to show how probit, logit, and similar techniques are related to the analysis of contingency tables. Finally, three unusual examples are described as illustrations of the care that is needed to avoid jumping to conclusions on how frequency data should be analysed.

scholarly journals Effects of fast rotation on the wind of Luminous Blue Variables

2010 ◽  
Vol 6 (S272) ◽  
pp. 56-61
Author(s):  
Jose H. Groh
Keyword(s):  
Near Infrared ◽  
Rotational Velocity ◽  
Spectral Lines ◽  
High Resolution Spectroscopy ◽  
Luminous Blue Variables ◽  
Eta Carinae ◽  
Fast Rotation ◽  
Long Baseline ◽  
Infrared Interferometry ◽  
Fast Rotating

AbstractWhile theoretical studies have long suggested a fast-rotating nature of Luminous Blue Variables (LBVs), observational confirmation of fast rotation was not detected until recently. Here I discuss the diagnostics that have allowed us to constrain the rotational velocity of LBVs: broadening of spectral lines and latitude-dependent variations of the wind density structure. While rotational broadening can be directly detected using high-resolution spectroscopy, long-baseline near-infrared interferometry is needed to directly measure the shape of the latitude-dependent photosphere that forms in a fast-rotating star. In addition, complex 2-D radiative transfer models need to be employed if one's goal is to constrain rotational velocities of LBVs. Here I illustrate how the above methods were able to constrain the rotational velocities of the LBVs AG Carinae, HR Carinae, and Eta Carinae.

Liquid Behavior in Containers with a Liquid-Packing Bag for Liquid Products Subjected to Drop Impact

2006 ◽  
Vol 321-323 ◽  
pp. 1280-1283 ◽  
Author(s):  
Eisaku Umezaki ◽  
Yuuma Shinoda ◽  
Katsunori Futase
Keyword(s):  
High Speed ◽  
Free Fall ◽  
The Other ◽  
Impact Loads ◽  
Visualization Technique ◽  
Transparent Plastic ◽  
Plastic Films ◽  
Liquid Behavior ◽  
Liquid Products ◽  
Polyethylene Particles

The behavior of liquid in containers subjected to impact loads due to free fall was investigated using a visualization technique. Two types of containers were used. One consisted of a case made of transparent plastic plates and a liquid-packing bag made of transparent plastic films. The bag contained about 1,000 ml of liquid. The other was a case made only of transparent plastic plates. The case contained about 1,000 ml of water. The liquid consisted of water and ethanol. Polyethylene particles of about 3 mm in diameter were included in the liquid to visualize the movement of liquid in the containers. The containers were subjected to impact due to free fall, and photographs of the containers were taken using a high-speed camera. Results indicated that the behavior of liquid in the container with a liquid-packing bag is different from that of the container without a liquid-packing bag.

Changes in Nutrient Levels of Lake Water Stored at 4 °C

1984 ◽  
Vol 41 (6) ◽  
pp. 985-988 ◽  
Author(s):  
A. H. El-Shaarawi ◽  
M. A. Neilson
Keyword(s):  
Statistical Analysis ◽  
Lake Water ◽  
Water Samples ◽  
Soluble Reactive Phosphorus ◽  
Lake Ontario ◽  
The Other ◽  
Nutrient Levels ◽  
Glass Bottles ◽  
Reactive Phosphorus

Water samples were collected on Lake Ontario during April and November, filtered (0.45 μm), and immediately analyzed onboard ship for the nutrients soluble reactive phosphorus, nitrate-plus-nitrite, and ammonia. Replicates were stored in glass bottles at 4 °C and reanalyzed within 8 d. Statistical analysis showed that soluble reactive phosphorus decreased by 11 and 13% and nitrate-plus-nitrite by 7 and 6%, whereas ammonia increased by 75% on one cruise and decreased by 37% on the other.

Practical Aspects of Propulsion Shaft Alignment

2021 ◽  
Author(s):  
Kyriakos Avgouleas ◽  
Emmanouil Sarris ◽  
George Gougoulidis
Keyword(s):  
Cost Effectiveness ◽  
Numerical Model ◽  
High Speed ◽  
The Other ◽  
Technical Literature ◽  
Trade Off ◽  
Fea Model ◽  
Shaft Alignment ◽  
Alignment Strategy ◽  
Potential Damage

The economical and operational implications of poor alignment are indisputable for the propulsion shafting system of a commercial vessel. This holds true for naval vessels as well, although far less documented in the technical literature. This paper addresses some of the challenges associated with the proper alignment of a high-speed naval craft, which has been in service for many years. Laser bore-sighting was performed on a Guided Missile Fast Patrol Boat resting on a docking cradle. The measured bearing offsets were input to a FEA model of the shafting system to calculate bearing reactions and detect potential misalignment issues. Subsequent decisions regarding corrective measures take into account the results computed by the numerical model, experience from sister ships, the available documentation from the building yard and several other factors which are discussed in the paper. The solutions proposed are targeted towards a balanced trade-off between cost effectiveness and out-of-service time on one hand, and the risk of potential damage from misalignment on the other hand, which would seriously disrupt the ship’s operational availability. Practical aspects and lessons identified in the process are also presented, which demonstrate the distinct differences in alignment strategy of a high-speed naval craft compared to a typical commercial vessel.

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