Quasi-Objective Coherent Structures from Single Lagrangian Trajectories

2021 ◽  
Author(s):  
Nikolas Aksamit ◽  
Alex Encinas Bartos ◽  
George Haller
Keyword(s):  
Coherent Structures ◽  
Sparse Data ◽  
Great Success ◽  
Trajectory Data ◽  
Atmospheric Flows ◽  
Local Material ◽  
Flow Features ◽  
Velocity Information ◽  
Flow Map

<p>Lagrangian coherent structures (LCS) provide a means to understand persistent flow features in an objective manner. There has been great success identifying and harnessing hyperbolic, elliptic, and parabolic structures in both oceanic and atmospheric flows. These approaches (e.g. FTLE, PRA, LAVD) rely on well resolved velocity information for the computation of the gradient of the flow map or vorticity deviation. Thus, for sparse data, such as that available from ocean drifters or atmospheric balloons, the quality of these methods quickly deteriorates. On the other hand, all elementary features of individual particle paths, such as velocity, acceleration, looping number, curvature and trajectory length, are non-objective, i.e., depend on the observer. To bridge this gap between LCS and sparse data, we derive measures of local material stretching and rotation that are computable from individual trajectories without reliance on other trajectories or on an underlying velocity field. Both measures are quasi-objective: they approximate objective (i.e., observer-independent) coherence diagnostics in frames satisfying a certain condition. We illustrate with several examples how our quasi-objective coherence diagnostics highlight elliptic and hyperbolic LCS, even from very sparse unstructured trajectory data. This approach shows great potential for expanding the possibilities of LCS applications through its simplicity, performance with sparse data, and enhanced computational efficiency.</p>

scholarly journals Comparative studies of some white wine cultivars in the sub-region of Belgrade and Nis

2004 ◽  
Vol 49 (1) ◽  
pp. 49-57
Author(s):  
Branislava Sivcev ◽  
Dragoslav Cvetkovic ◽  
Nevena Petrovic ◽  
Ivana Popadic
Keyword(s):  
Total Yield ◽  
Grape Juice ◽  
Experimental Period ◽  
White Wine ◽  
High Yield ◽  
Great Success ◽  
Air Temperatures ◽  
Grape Quality ◽  
Climatic Characteristics

In two wine-growing areas with different climatic characteristics 12 cultivars intended for the production of white wines were studied. The climatic characteristics include: mean annual air temperatures, mean vegetation air temperatures, heliothermal coefficient, hydrothermal coefficient and active temperatures sum from the moment of the growth of shoots to their full maturity for each studied cultivar. Elements of buds fruitfulness (6 features in total), yield, cluster mass, sugar quantity and grape quality were observed in both localities. In the vineyards of Grocka and Kutina high yielding varieties Ugni blanc and Dimyat can be grown with great success. Italian Riezling produced higher yields and better quality of unfermented grape juice in the vineyards of Grocka in comparison with the vineyards of Kutina. Pinot blanc in both localities was characterized by high yield, but the quality of unfermented grape juice was better in the vineyards of Grocka. Variety Rkaciteli produced high yield and good quality of unfermented grape juice in the experimental period in the vineyards of Kutina.

Peer-to-Peer Video Streaming

2014 ◽  
pp. 169-228
Author(s):  
Jânio M. Monteiro ◽  
Rui S. Cruz ◽  
Charalampos Z. Patrikakis ◽  
Nikolaos C. Papaoulakis ◽  
Carlos T. Calafate ◽  
...  
Keyword(s):  
Video Streaming ◽  
Ip Networks ◽  
Peer To Peer ◽  
The Internet ◽  
Special Focus ◽  
Great Success ◽  
Multicast Protocols ◽  
Video Distribution ◽  
To Receive

The Internet as a video distribution medium has seen a tremendous growth in recent years. Currently, the transmission of major live events and TV channels over the Internet can easily reach hundreds or millions of users trying to receive the same content using very distinct receiver terminals, placing both scalability and heterogeneity challenges to content and network providers. In private and well-managed Internet Protocol (IP) networks these types of distributions are supported by specially designed architectures, complemented with IP Multicast protocols and Quality of Service (QoS) solutions. However, the Best-Effort and Unicast nature of the Internet requires the introduction of a new set of protocols and related architectures to support the distribution of these contents. In the field of file and non-real time content distributions this has led to the creation and development of several Peer-to-Peer protocols that have experienced great success in recent years. This chapter presents the current research and developments in Peer-to-Peer video streaming over the Internet. A special focus is made on peer protocols, associated architectures and video coding techniques. The authors also review and describe current Peer-to-Peer streaming solutions.

scholarly journals Sensor Fusion-Based Cooperative Trail Following for Autonomous Multi-Robot System

Sensors ◽  
2019 ◽  
Vol 19 (4) ◽  
pp. 823 ◽  
Author(s):  
Mingyang Geng ◽  
Shuqi Liu ◽  
Zhaoxia Wu
Keyword(s):  
Sensor Fusion ◽  
Sensor Data ◽  
Great Success ◽  
Trail Following ◽  
Robust Performance ◽  
Robot System ◽  
Threshold Mechanism ◽  
Local View ◽  
In The Wild

Autonomously following a man-made trail in the wild is a challenging problem for robotic systems. Recently, deep learning-based approaches have cast the trail following problem as an image classification task and have achieved great success in the vision-based trail-following problem. However, the existing research only focuses on the trail-following task with a single-robot system. In contrast, many robotic tasks in reality, such as search and rescue, are conducted by a group of robots. While these robots are grouped to move in the wild, they can cooperate to lead to a more robust performance and perform the trail-following task in a better manner. Concretely, each robot can periodically exchange the vision data with other robots and make decisions based both on its local view and the information from others. This paper proposes a sensor fusion-based cooperative trail-following method, which enables a group of robots to implement the trail-following task by fusing the sensor data of each robot. Our method allows each robot to face the same direction from different altitudes to fuse the vision data feature on the collective level and then take action respectively. Besides, considering the quality of service requirement of the robotic software, our method limits the condition to implementing the sensor data fusion process by using the “threshold” mechanism. Qualitative and quantitative experiments on the real-world dataset have shown that our method can significantly promote the recognition accuracy and lead to a more robust performance compared with the single-robot system.

Special Issue on New Frontiers in Research on Robotics and Mechatronics (Part 1)

2011 ◽  
Vol 23 (2) ◽  
pp. 200-200
Author(s):  
Yasuhisa Hasegawa ◽  
Keiji Suzuki
Keyword(s):  
Big Bang ◽  
Program Committee ◽  
Great Success ◽  
Special Issue ◽  
Program Chair ◽  
Conference Theme ◽  
Original Works ◽  
Very High ◽  
Made In

Robotics and Mechatronics Conference 2010 (ROBOMEC’10) was held at the Asahikawa Taisetsu arena in Asahikawa, Japan, on June 13-16, 2010, sponsored by the Robotics and Mechatronics Division of the Japan Society of Mechanical Engineers (JSME). Prof. Masashi Furukawa of Hokkaido University served as the General Chair and Prof. Keiji Suzuki of Hokkaido University as the Program Chair. The conference theme was “Robotics, Mechatronics, Big-bang, Frontier,” detailing expectations of major technology expansion in robotics and mechatronics. Over 1,100 presentations were made in 86 sessions, and participants numbered 1500 including those from abroad, making it a great success. The ROBOMEC’10 program committee selected 136 outstanding presentations. We recommended that authors submit original works for this issue, and received 53 papers. This special issue, Part 1 presents 15 papers strictly reviewed and accepted from among them. The remaining accepted papers will appear in the next issue as Part 2. We are pleased with the very high quality of these papers, and are confident that readers will find them both interesting and instructive in the fields of robotics and mechatronics. We thank the authors for their invaluable contributions and the reviewers for their time and effort. We also thank Editor-in-Chief Prof. Tatsuo Arai of Osaka University for organizing this special issue.

Research on Vessel Trajectory Multi-Dimensional Compression Algorithm Based on Douglas-Peucker Theory

2014 ◽  
Vol 694 ◽  
pp. 59-62 ◽  
Author(s):  
Fei Xiang Zhu ◽  
Li Ming Miao ◽  
Wen Liu
Keyword(s):  
Compression Algorithm ◽  
Spatial Distance ◽  
Automatic Identification ◽  
Identification System ◽  
Trajectory Data ◽  
Compression Process ◽  
Maritime Traffic ◽  
Offset Distance ◽  
Improved Algorithm

Currently, maritime safety administrations or shipping company had received a large number of vessel trajectory data from Automatic Identification System (AIS). In order to more efficiently carry out research of maritime traffic flow, ship behavior and maritime investigation, it is important to ensure the quality of the vessel trajectory data under compression condition. In classic Douglas-Peucker vector data compression algorithm, offset spatial distance of each point was the single factor in compression process. In order to overcome the shortcomings of classic Douglas-Peucker, a vessel trajectory multi-dimensional compression improved algorithm is proposed. In improved algorithm, the concept of single trajectory point importance which considers the point offset distance and other vessel handling factors, such as the vessel turning angle, speed variation, is proposed to as the compression index. Compared to classic Douglas-Peucker algorithm, experiment results show that the proposed multi-dimensional vessel trajectory compression improved algorithms can effectively retain characteristics of navigation.

scholarly journals Lagrangian Coherent Structure Analysis of Terminal Winds: Three-Dimensionality, Intramodel Variations, and Flight Analyses

2015 ◽  
Vol 2015 ◽  
pp. 1-13 ◽  
Author(s):  
Brent Knutson ◽  
Wenbo Tang ◽  
Pak Wai Chan
Keyword(s):  
Coherent Structures ◽  
Three Dimensional ◽  
Light Detection And Ranging ◽  
Flow Structures ◽  
Lidar Data ◽  
Two Dimensional ◽  
Lagrangian Coherent Structure ◽  
Flight Data ◽  
Velocity Information ◽  
Hong Kong International Airport

We present a study of three-dimensional Lagrangian coherent structures (LCS) near the Hong Kong International Airport and relate to previous developments of two-dimensional (2D) LCS analyses. The LCS are contrasted among three independent models and against 2D coherent Doppler light detection and ranging (LIDAR) data. Addition of the velocity information perpendicular to the LIDAR scanning cone helps solidify flow structures inferred from previous studies; contrast among models reveals the intramodel variability; and comparison with flight data evaluates the performance among models in terms of Lagrangian analyses. We find that, while the three models and the LIDAR do recover similar features of the windshear experienced by a landing aircraft (along the landing trajectory), their Lagrangian signatures over the entire domain are quite different—a portion of each numerical model captures certain features resembling those LCS extracted from independent 2D LIDAR analyses based on observations.

On the flow and coherent structures generated by a circular array of rigid emerged cylinders placed in an open channel with flat and deformed bed

2017 ◽  
Vol 831 ◽  
pp. 1-40 ◽  
Author(s):  
Wen-Yi Chang ◽  
George Constantinescu ◽  
Whey Fone Tsai
Keyword(s):  
Shear Stress ◽  
Coherent Structures ◽  
Open Channel ◽  
Bed Shear Stress ◽  
Porous Cylinder ◽  
Flow Acceleration ◽  
Drag Forces ◽  
Flow Features ◽  
The Mean ◽  
Porous Cylinders

The flow and the turbulence structure generated by a circular porous cylinder of diameter $D$ containing solid cylinders of diameter $d$ placed in an open channel of depth $h\approx 0.5D$ are investigated using eddy-resolving simulations which resolve the wakes past the individual solid cylinders in the array. The solid cylinders extend from the bed through the water surface. This geometrical set-up is directly relevant to understand the physics of flow past an emerged patch of aquatic vegetation developing in a river channel or over its floodplain. Simulations are conducted with different solid volume fractions (SVFs) of the porous cylinder ($0.034<\text{SVF}<0.23$), relative diameters of the solid cylinders ($d/D=0.03$ and 0.06) and with flat and equilibrium scour bathymetry corresponding to the start and respectively the end of the erosion and deposition process. Comparison with the limiting case of a solid cylinder ($\text{SVF}=1$) is also discussed. The bed shear stress distributions and the turbulent flow fields are used to explain the sediment erosion mechanisms inside and around the porous cylinder. Simulations of the flat-bed cases reveal that for sufficiently large SVF values ($\text{SVF}>0.2$), necklace vortices form around the upstream face of the cylinder, the downflow penetrates partially inside the porous cylinder and a region of strong flow acceleration forms on the sides of the porous cylinder. These flow features are used to explain the development of scour around high-SVF porous cylinders. The effects of the SVF and $d/D$ on generating ‘corridors’ of strong flow acceleration in between the solid cylinders and energetic eddies in the wake of these cylinders are discussed, as these flow features control the amplification of the bed shear stress inside the porous cylinder. Simulations results are also used to quantify the time-averaged drag forces on the cylinders in the array, to identify the regions where these forces are comparable to those induced on an isolated cylinder and the percentage of cylinders in the array subject to relatively large mean drag forces. A logarithmic decrease of the mean time-averaged streamwise drag coefficient of the solid cylinders, $\overline{C}_{d}$, with increasing non-dimensional frontal area per unit volume of the porous cylinder, $aD$, is observed. Behind the cylinder, the eddies shed in the separated shear layers (SSLs) of the porous cylinder, and, for sufficiently large SVFs, the von Kármán wake billows are the main coherent structures responsible for the amplification of the bed shear stress and sediment entrainment. This paper also analyses the vertical non-uniformity of the mean flow and turbulent kinetic energy, and discusses how the SVF and bathymetry affect the spatial extent of the wake region (e.g. length of the SSLs and steady wake, total wake length) and other relevant variables (e.g. strength of the bleeding flow, dominant wake frequencies, turbulence amplification in the near wake). For the relatively shallow flow conditions ($D/h\approx 2.0$) considered, the simulation results show that the antisymmetric (von Kármán) shedding of wake billows behind the porous cylinder is greatly weakened once equilibrium scour conditions are approached. Comparison with data from laboratory experiments and from 3-D and 2-D simulations conducted for long porous cylinders (no bed) is also discussed.

scholarly journals SPIRITUALITAS SANG NABI (Analisis nilai dekonstruksi dalam puisi prosa Sang Nabi karya Kahlil Gibran)

Spiritualita ◽  
2019 ◽  
Vol 2 (2) ◽  
Author(s):  
Muhammad Zuhdi
Keyword(s):  
Content Analysis ◽  
Qualitative Study ◽  
World View ◽  
Great Success ◽  
Main Character ◽  
Modern Logic ◽  
Analysis Technique ◽  
The World ◽  
Love Marriage

There is no one ever doubts the quality of Kahlil Gibran as a poet or man of letters. His great name is the guarantee of his literature works’ quality. Almost every work, most of them are prose poetry, gain great success, and one of the indications is by translating into various languages in the world, including Indonesian. One of his most success works and receives international acknowledgment as well as his own admission as his best work is The Prophet. The Prophet includes many lessons bearing deconstruction values, which has been proven in this study. Deconstruction values within The Prophet is still inherent in each statement of its main character (Al Mustafa/Gibran) about topic concerning with many kinds of human problems, such as love, marriage, child, friendship, beauty, happiness, sadness, work, religion, and even death. In this study those values were contrasted or compared to various realities in form of text and social fenomena of the community in order to find their contradictions or similarities. This qualitative study used moral approach because its review material is intrinsic aspect of a literature works related to values. While the analysis technique used content analysis because it tried to disclose, understand, and catch the massage beneath the literature work. While the “knite” used to cut and disentangle its values is deconstruction. Deconstruction is an idea which strive to cope the world view which has been boxed all along within a normative understanding that this world consists of two opposing elements, such as rational-irrational, traditional- modern, logic-illogic, good-bad, man-women, and so on. Then deconstruction tries to look for gaps or alternatives between the two opposing elements. Thus, deconstruction is not always extreme in its meaning: confirm or nullify.

scholarly journals Groundwater and river water interaction to solve water shortage: a case from Tasikmalaya, Indonesia

2014 ◽  
Author(s):  
Dasapta E Irawan ◽  
Cut N Rachmi ◽  
Aditya Pratama ◽  
Gusti P Tulak ◽  
Achmad D Rochman
Keyword(s):  
River Water ◽  
Flow System ◽  
Water Shortage ◽  
Point Of View ◽  
Physical Parameters ◽  
Raw Water ◽  
Water Characteristics ◽  
Dug Wells ◽  
Flow Map

Water shortage is a common problem in the high density settlement along the riverbank of Ciromban and Cibeureum River, Tasikmalaya, as the quality of the water also decreases. One of the solution is to maximize the use of river water. This study aims to investigate the interaction between river and groundwater along the riverbank as a function of land use impact. A river water and unconfined groundwater level mapping has been conducted to make water flow map, assuming both waters are in the same flow system. Physical parameters, temperature, TDS, and pH were measured at each stations to understand water characteristics. Based on observations at 50 dug wells and 12 river stations on July-August 2014, a close interaction between both water bodies has been identified with two flow systems: effluent flow (or gaining stream) at Cibereum river segment and influent flow (losing stream) at Ciromban river segment. Physical parameters show a high correlation in temperature, pH, and TDS. Hence, further evaluation from health point of view should be taken before using river water as raw water supply in Tasikmalaya area.

scholarly journals Determination and Evaluation of the Cooling Load of a Building Made by Different Local Material of Construction

2020 ◽  
Vol 15 (1) ◽  
pp. 1
Author(s):  
AMADOU OUMAROU Fati ◽  
Ramchandra BHANDARI ◽  
MAMADOU Lewamy ◽  
KY Thierry S.M ◽  
OUEDRAOGO Souleymane ◽  
...  
Keyword(s):  
Burkina Faso ◽  
Energy Demand ◽  
Cooling System ◽  
Building Design ◽  
Well Being ◽  
Raw Material ◽  
Existing Building ◽  
Local Material ◽  
Local Materials

This paper aims to describe a passive approach to reduce the energy demand for an existing building and can be made through an improvement of the design of the thermal envelope. The essential article goal is to simulate thermal construction responses in dependence on changing different materials of the construction of the building and also with less energy usage to design a more effective cooling system. In this approach, we simulate the building with different materials: three local materials (compressed earth, lateritic, and raw material) and one modern (Hollow cement) used in Burkina Faso and an energy analysis of the building has been carried out. The numerical optimization of the building design has been performed dynamically for these four materials using the COMSOL multiphysics simulation tool. The model treated is determining the internal temperature and cooling demand concerning a tertiary building in Burkina Faso like a classroom, which is located in a hot and dry climate to improve the indoor quality of the classroom knowing the importance of the thermal comfort in the room for socio-economic performance efficiency and well-being. The analysis result of these four materials shows that energy can be saved if we use local materials instead of the modern one because around 4KW of energy can be saving with local materials. The use of local materials in the building design can be an option for reducing the heat transfer into the room and at the same time the energy consumption.

Sign in / Sign up

Export Citation Format

Share Document