Active Flow Control and Dynamic Analysis in Droplet Microfluidics

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Nan Shi ◽  
Md Mohibullah ◽  
Christopher J. Easley
Keyword(s):  
Active Flow Control ◽  
Research Area ◽  
Droplet Microfluidics ◽  
Annual Review ◽  
Publication Date ◽  
Analytical Methodology ◽  
Mass Spectrometers ◽  
Control Techniques ◽  
Fluidic Control ◽  
Active Flow

Droplet-based microfluidics has emerged as an important subfield within the microfluidic and general analytical communities. Indeed, several unique applications such as digital assay readout and single-cell sequencing now have commercial systems based on droplet microfluidics. Yet there remains room for this research area to grow. To date, most analytical readouts are optical in nature, relatively few studies have integrated sample preparation, and passive means for droplet formation and manipulation have dominated the field. Analytical scientists continue to expand capabilities by developing droplet-compatible method adaptations, for example, by interfacing to mass spectrometers or automating droplet sampling for temporally resolved analysis. In this review, we highlight recently developed fluidic control techniques and unique integrations of analytical methodology with droplet microfluidics—focusing on automation and the connections to analog/digital domains—and we conclude by offering a perspective on current challenges and future applications. Expected final online publication date for the Annual Review of Analytical Chemistry, Volume 14 is August 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Behavior Trees in Robot Control Systems

2021 ◽  
Vol 5 (1) ◽  
Author(s):  
Petter Ögren ◽  
Christopher I. Sprague
Keyword(s):  
Control System ◽  
Feedback Control ◽  
Robot Control ◽  
Autonomous Systems ◽  
Research Area ◽  
Annual Review ◽  
Publication Date ◽  
Detailed Knowledge ◽  
Level Control ◽  
Behavior Trees

In this article, we provide a control-theoretic perspective on the research area of behavior trees in robotics. The key idea underlying behavior trees is to make use of modularity, hierarchies, and feedback in order to handle the complexity of a versatile robot control system. Modularity is a well-known tool to handle software complexity by enabling the development, debugging, and extension of separate modules without detailed knowledge of the entire system. A hierarchy of such modules is natural, since robot tasks can often be decomposed into a hierarchy of subtasks. Finally, feedback control is a fundamental tool for handling uncertainties and disturbances in any low-level control system, but in order to enable feedback control on the higher level, where one module decides what submodule to execute, information regarding the progress and applicability of each submodule needs to be shared in the module interfaces. We describe how these three concepts can be used in theoretical analysis, practical design, and extensions and combinations with other ideas from control theory and robotics. Expected final online publication date for the Annual Review of Control, Robotics, and Autonomous Systems, Volume 5 is May 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

scholarly journals Networks of Conflict and Cooperation

2021 ◽  
Vol 24 (1) ◽  
Author(s):  
Jennifer M. Larson
Keyword(s):  
Peer Pressure ◽  
Research Area ◽  
Future Research ◽  
Annual Review ◽  
Publication Date ◽  
Informal Governance ◽  
Major Step ◽  
Conflict And Cooperation ◽  
Early Results ◽  
New Research

Conflict and cooperation do not result from isolated individual actions. In settings such as insurgency, interstate conflict, protest mobilization, and informal governance, actors are highly interdependent. The study of networks aims to identify what the relevant interdependencies are and, crucially, how they shape conflict and cooperation outcomes. Although this is a relatively new research area, its early results convincingly establish that networks matter. Social networks provide information, transmit peer pressure, and structure interactions in ways that help groups overcome social dilemmas. With much research documenting the importance of particular outcomes in particular areas, the next major step will be putting the pieces together. Which connections between actors matter in which circumstances and how? The groundwork has been well laid for this large future research endeavor. Expected final online publication date for the Annual Review of Political Science, Volume 24 is May 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

scholarly journals Conceptual Design of a Novel Unmanned Ground Effect Vehicle (UGEV) and Flow Control Integration Study

Drones ◽  
2022 ◽  
Vol 6 (1) ◽  
pp. 25
Author(s):  
Charalampos Papadopoulos ◽  
Dimitrios Mitridis ◽  
Kyros Yakinthos
Keyword(s):  
Flow Control ◽  
Conceptual Design ◽  
Active Flow Control ◽  
Ground Effect ◽  
Passive Flow Control ◽  
Control Techniques ◽  
Passive Flow ◽  
Conceptual Design Phase ◽  
Wide Range ◽  
Active Flow

In this study, the conceptual design of an unmanned ground effect vehicle (UGEV), based on in-house analytical tools and CFD calculations, followed by flow control studies, is presented. Ground effect vehicles can operate, in a more efficient way, over calm closed seas, taking advantage of the aerodynamic interaction between the ground and the vehicle. The proposed UGEV features a useful payload capacity of 300 kg and a maximum range of 300 km cruising at 100 kt. Regarding the aerodynamic layout, a platform which combines the basic geometry characteristics of the blended wing body (BWB), and box wing (BXW) configurations is introduced. This hybrid layout aims to incorporate the most promising features from both configurations, while it enables the UGEV to operate under adverse flight conditions of the atmospheric boundary layer of the earth. In order to enhance the performance characteristics of the platform, both passive and active flow control techniques are studied and incorporated into the conceptual design phase of the vehicle. For the passive flow control techniques, the adaptation of tubercles and wing fences is evaluated. Regarding the active flow control techniques, a wide range of morphing technologies is investigated based on performance and integration criteria. Finally, stability studies are conducted for the proposed platform.

Active Flow Control Techniques on a Stator Compressor Cascade: A Comparison Between Synthetic Jet and Plasma Actuators

2012 ◽  
Author(s):  
Maria Grazia De Giorgi ◽  
Stefania Traficante ◽  
Carla De Luca ◽  
Daniela Bello ◽  
Antonio Ficarella
Keyword(s):  
Boundary Layer ◽  
Flow Control ◽  
Active Flow Control ◽  
Pressure Ratio ◽  
Boundary Layer Separation ◽  
Synthetic Jet ◽  
Plasma Actuators ◽  
Compressor Cascade ◽  
Control Techniques ◽  
Active Flow

In this work a CFD analysis is applied to study the suppression of the boundary layer separation into a highly-loaded subsonic compressor stator cascade, by different active flow control techniques. Active flow control techniques have the potential to delay separation and to increase the pressure ratio. In particular three different techniques have been applied: the actuation by steady jet, by zero net mass flux Synthetic Jet (SJA) and by plasma actuator. Several works have investigated the use of synthetic jet and plasma actuators on the airfoil, but only few studies have compared the effect of these devices. Concerning the synthetic jet actuator, a suction/blowing type boundary condition is used, imposing a prescribed sinusoidal velocity depending on velocity amplitude, jet frequency and jet angle of ejection with respect to the wall. Concerning the plasma actuation, the effect is modeled into numerical flow solvers by adding the paraelectric force that represents the plasma force into the momentum equation. The plasma, generated by Dielectric Barrier Discharge, acts as a momentum source to the boundary layer allowing it to remain attached throughout a larger portion of the airfoil. The time-averaged body force component, acting on the fluid, depends on the frequency and on the applied voltage, the charge density, the electrical field and the dimensional properties of the actuator, like width of the electrodes and gap between the electrodes. Using this numerical model, the effect of plasma actuators to suppress the flow separation over the blade has been investigated, increasing the turbo-machinery performance too. Finally, the comparison between the different actuation devices shows that, reducing the secondary flow structures, each actuation technique beneficially affects the performance of the stator compressor cascade, even if in the steady jet the costs are relevant.

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