Study of Pc5 compressional waves by MMS observations

2021 ◽  
Author(s):  
Anmin Tian
Keyword(s):  
Wave Structure ◽  
Tetrahedral Configuration ◽  
Compressional Waves ◽  
Structure And Motion ◽  
Time Period ◽  
Spatial Coverage ◽  
Compressional Mode ◽  
Mirror Mode ◽  
Motion Characteristics ◽  
Magnetic Bottle

<p>Pc5 compressional waves are frequently observed in the outer magnetosphere with mirror mode features. Due to the limited spatial coverage of spacecraft, their overall structure is still poorly understood. In this work, the wave structure and motion characteristics are statistically investigated based on the MMS data from September to October 2015. During this time period, the apogees of the MMS spacecraft were located in the outer dusk magnetosphere, and the spacecraft has regular tetrahedral configuration that facilitates the application of multi-spacecraft analysis techniques. The magnetic trough boundaries are identified, and their normal direction, current density and velocity of these boundaries are calculated. We found that the magnetic trough has a magnetic bottle topology along the field line. In the r-a plane, the two boundaries has an open angle toward the radial direction.The boundaries mainly move sunward in the GSE XY plane with average speed of ~26km/s. The poloidal Alfven mode is found to be coupling with the compressional mode oscillation. It suggests that our observations could be explained by the theory of drift Alfven ballooning mirror instability.</p>

Analysis of Turnover Mechanism of the Aluminum Electrolytic Capacitor Assembling Machine

2013 ◽  
Vol 341-342 ◽  
pp. 438-442
Author(s):  
Zhou Zheng ◽  
Bi Zhong Xia ◽  
Yi Ran Liu ◽  
Zhong Dong Ouyang
Keyword(s):  
Dynamic Analysis ◽  
Optimization Design ◽  
Parametric Modeling ◽  
Resultant Force ◽  
Electrolytic Capacitor ◽  
Aluminum Electrolytic Capacitor ◽  
Mechanism Optimization ◽  
Structure And Motion ◽  
Adams Software ◽  
Motion Characteristics

Turnover mechanism is one of the important parts of the element bar conveying subsystem in the aluminum electrolytic capacitor assembling machine (AECAM). This paper analyzed the structure and motion characteristics of the turnover mechanism, and used the ADAMS software to do its parametric modeling, dynamic analysis and optimization design. Finally the paper concluded that Final result of turnover mechanism optimization was that the maximum of resultant force in the cam rotary center decreased by 49.3%.Application of ADAMS software will provide a new way for design and improvement of the assembling machine in future.

scholarly journals Structure and Motion of Severe-Wind-Producing Mesoscale Convective Systems and Derechos in Relation to the Mean Wind

2017 ◽  
Vol 32 (2) ◽  
pp. 423-439 ◽  
Author(s):  
Matthew A. Campbell ◽  
Ariel E. Cohen ◽  
Michael C. Coniglio ◽  
Andrew R. Dean ◽  
Stephen F. Corfidi ◽  
...  
Keyword(s):  
Large Scale ◽  
Mean Flow ◽  
Convective Systems ◽  
Structure And Motion ◽  
Mesoscale Convective ◽  
The Mean ◽  
Wind Events ◽  
Motion Characteristics ◽  
Definition Of ◽  
Convective Vortices

Abstract The goal of this study is to document differences in the convective structure and motion of long-track, severe-wind-producing MCSs from short-track severe-wind-producing MCSs in relation to the mean wind. An ancillary goal is to determine if these differences are large enough that some criterion for MCS motion relative to the mean wind could be used in future definitions of “derechos.” Results confirm past investigations that well-organized MCSs, including those that produce derechos, tend to move faster than the mean wind, exhibiting a significantly larger degree of propagation (component of MCS motion in addition to the component contributed by the mean flow). Furthermore, well-organized systems that produce shorter-track swaths of damaging winds likewise tend to move faster than the mean wind with a significant propagation component along the mean wind. Therefore, propagation in the direction of the mean wind is not necessarily a characteristic that can be used to distinguish derechos from nonderechos. However, there is some indication that long-track damaging wind events that occur without large-scale or persistent bow echoes and mesoscale convective vortices (MCVs) require a strong propagation component along the mean wind direction to become long lived. Overall, however, there does not appear to be enough separation in the motion characteristics among the MCS types to warrant the inclusion of a mean-wind criterion into the definition of a derecho at this time.

scholarly journals Observations of iodine monoxide (IO) columns from satellite

2007 ◽  
Vol 7 (5) ◽  
pp. 12959-12999 ◽  
Author(s):  
A. Schönhardt ◽  
A. Richter ◽  
F. Wittrock ◽  
H. Kirk ◽  
H. Oetjen ◽  
...  
Keyword(s):  
Chlorophyll Concentration ◽  
Arctic Region ◽  
The Arctic ◽  
Polar Regions ◽  
Satellite Measurements ◽  
Ice Coverage ◽  
Iodine Monoxide ◽  
Time Period ◽  
Iodine Compounds ◽  
Spatial Coverage

Abstract. Iodine species in the troposphere are linked to ozone depletion and new particle formation. In this study, a full year of iodine monoxide (IO) columns retrieved from measurements of the SCIAMACHY satellite instrument is presented, alongside a discussion of their uncertainties and the detection limit. The largest amounts of IO are found near springtime Antarctica, where ground-based measurements have positively detected iodine compounds before. A seasonal variation of iodine monoxide in Antarctica is revealed with high values in springtime, slightly less IO in the summer period and again larger amounts in autumn. In winter, no elevated IO levels are found in the areas accessible to satellite measurements. This seasonal cycle is in good agreement with recent ground-based measurements in Antarctica. In the Arctic region, no elevated IO levels were found in the whole time period analysed, arguing for different conditions existing in the two Polar Regions. To investigate possible release mechanisms such as inorganic release or biogenic precursors, comparisons of IO results with tropospheric BrO maps, measurements of chlorophyll concentration, and ice coverage are discussed. Some parallels and interesting differences between IO and BrO temporal and spatial distributions are pointed out. Although no full interpretation can be given at this point, the large spatial coverage of satellite measurements and the availability of a long-term dataset give some new indications and understandings of the abundances and distributions of iodine compounds in the troposphere.

scholarly journals Structure and Motion Characteristics of an Optical Microgripper.

1993 ◽  
Vol 59 (559) ◽  
pp. 799-806 ◽  
Author(s):  
Shinobu Hattori ◽  
Toshio Fukuda ◽  
Toshihiro Maruhashi ◽  
Hideo Matsuura ◽  
Shigenobu Nagamori
Keyword(s):  
Structure And Motion ◽  
Motion Characteristics

scholarly journals Effects of temporal resolution of input precipitation on the performance of hydrological forecasting

2011 ◽  
Vol 29 ◽  
pp. 21-25 ◽  
Author(s):  
F. Wetterhall ◽  
Y. He ◽  
H. Cloke ◽  
F. Pappenberger
Keyword(s):  
Flood Forecasting ◽  
Lead Times ◽  
Data Sets ◽  
Precipitation Data ◽  
Hydrological Models ◽  
Data Set ◽  
Flood Prediction ◽  
Time Period ◽  
Spatial Coverage ◽  
Prediction Systems

Abstract. Flood prediction systems rely on good quality precipitation input data and forecasts to drive hydrological models. Most precipitation data comes from daily stations with a good spatial coverage. However, some flood events occur on sub-daily time scales and flood prediction systems could benefit from using models calibrated on the same time scale. This study compares precipitation data aggregated from hourly stations (HP) and data disaggregated from daily stations (DP) with 6-hourly forecasts from ECMWF over the time period 1 October 2006–31 December 2009. The HP and DP data sets were then used to calibrate two hydrological models, LISFLOOD-RR and HBV, and the latter was used in a flood case study. The HP scored better than the DP when evaluated against the forecast for lead times up to 4 days. However, this was not translated in the same way to the hydrological modelling, where the models gave similar scores for simulated runoff with the two datasets. The flood forecasting study showed that both datasets gave similar hit rates whereas the HP data set gave much smaller false alarm rates (FAR). This indicates that using sub-daily precipitation in the calibration and initiation of hydrological models can improve flood forecasting.

Theoretical Analysis of Mechanism Kinematics for Boom Crane of Marine Drilling Platform

2013 ◽  
Vol 433-435 ◽  
pp. 53-58
Author(s):  
Jun Qiang Li ◽  
Yong Peng ◽  
Wen Hui Yan
Keyword(s):  
Automatic Control ◽  
Theoretical Basis ◽  
Inverse Kinematics ◽  
Forward Kinematics ◽  
Structure And Motion ◽  
Mechanics Analysis ◽  
Engineering Significance ◽  
Motion Characteristics ◽  
Joint Coordinate System ◽  
Boom Crane

The boom crane of marine drilling platform is an important part of the automated pipe racking system. It has important engineering significance to study the kinematics of boom crane for the automatic control and accurate positioning. Using the method of robot mechanisms, the kinematics of mechanism for boom crane on marine drilling platform is discussed in this paper. According to the structure and motion characteristics of the boom crane, a special joint coordinate system is chosen. The kinematics model of the boom crane is established. The forward kinematics equations, inverse kinematics calculation formulas are derived. The correctness of formulas is verified by examples. The theoretical basis is provided for the movement automatic control and subsequent dynamics and boom crane mechanics analysis when considering the elastic deformation.

scholarly journals Observation of drift compressional waves with a mid-latitude decameter coherent radar

2016 ◽  
Vol 2 (2) ◽  
pp. 46-56 ◽  
Author(s):  
Максим Челпанов ◽  
Maksim Chelpanov ◽  
Павел Магер ◽  
Pavel Mager ◽  
Дмитрий Климушкин ◽  
...  
Keyword(s):  
Ionospheric Plasma ◽  
Wave Number ◽  
Frequency Increase ◽  
Compressional Waves ◽  
Absolute Value ◽  
Compressional Mode ◽  
Existence Conditions ◽  
Cross Wavelet Analysis ◽  
Coherent Radar ◽  
Cross Wavelet

Magnetospheric Pc5 pulsations observed on December 26, 2014 are analyzed. They were recorded in the nightside magnetosphere with a mid-latitude coherent decameter radar located near Ekaterinburg. It registers velocity variations in electric drift of ionospheric plasma caused by ULF waves in the magnetosphere. The westward direction of azimuthal propagation of wave coincides with the direction of magnetic drift of protons. A cross-wavelet analysis reveals that the frequency of oscillations depends on the wave number m, and the correlation between them is 0.90. The frequency increase from 2.5 to 5 mHz was followed by an increase in the absolute value m from 20 to 80. These features of the wave under study testify that it should be classified as a drift compressional mode which is typical for the ULF mode in kinetics. Existence conditions for it are the terminal pressure of plasma and its inhomogeneity across magnetic shells.

scholarly journals Design and Control of an Adaptive Knee Joint Exoskeleton Mechanism with Buffering Function

Sensors ◽  
2021 ◽  
Vol 21 (24) ◽  
pp. 8390
Author(s):  
Yapeng Wang ◽  
Wei Zhang ◽  
Di Shi ◽  
Yunhai Geng
Keyword(s):  
Knee Joint ◽  
Tracking Error ◽  
Adaptive Controller ◽  
Average Force ◽  
Human Knee ◽  
Rotation Center ◽  
Structure And Motion ◽  
System A ◽  
Motion Characteristics ◽  
And Control

A knee exoskeleton with an adaptive instantaneous rotation center and impact absorption is used for rehabilitation. Due to the human knee joint’s special physiological structure and motion characteristics, the exoskeleton mechanism needs to be designed for both static and dynamic aspects. Therefore, a novel knee exoskeleton mechanism was designed. To adapt to the rotation center of the knee joint, a mechanism with cross-configuration was designed according to the equivalent degree of freedom and the stiffness of the springs was calculated by its combination with gait motion, so that the average force of the human body was minimized. A dynamic model of the exoskeleton was established. To overcome the uncertainty in the parameters of the human and robotic limbs, an adaptive controller was designed and a Lyapunov stability analysis was conducted to verify the system. A simulation was conducted and experimental results show that the tracking error of the knee joint angle between the actual and desired trajectory was within the range of −1 to 1 degree and indicate the effectiveness of the controller.

Topology Structure Design of 12 Flapping-Wing Mechanisms

2011 ◽  
Vol 328-330 ◽  
pp. 887-891 ◽  
Author(s):  
Meng Hui Hsu ◽  
Hsueh Yu Chen ◽  
Ting Sheng Weng ◽  
Feng Chi Liu
Keyword(s):  
Topological Structure ◽  
Micro Air Vehicles ◽  
Structure Design ◽  
Flapping Wing ◽  
Design Criteria ◽  
Wing Motion ◽  
Structure And Motion ◽  
Motion Characteristics ◽  
The Military ◽  
Air Vehicles

People used the Micro Air Vehicles to patrol the military activity or explore the danger region.The important parts of Micro Air Vehicles are the flapping-wing mechanisms those can simulate the wing-motion of flying being.Hence this work is to present a systematic approach for designing new flapping-wing mechanisms with one degree of freedom that can simulate the wing-motion of long ear bats and insects.First,we analyze the topological structure and motion characteristics of existed flapping mechanisms.Then, the design criteria of the topological structure are described.Based on the design criteria of topology, the methodology of mechanism design is applied to synthesize new flapping-wing mechanisms. Finally, this research of the provide method can obtain 12 new flapping -wing mechanisms and one prototype of a flying insect mechanism.

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