Simplified Explicit Flow Equations for Herschel-Bulkley Fluids in Couette-Poiseuille Flow—For Real-Time Surge and Swab Modeling in Drilling

SPE Journal ◽  
2015 ◽  
Vol 20 (03) ◽  
pp. 610-627 ◽  
Author(s):  
Kristian Gjerstad ◽  
Rune W. Time
Keyword(s):  
Real Time ◽  
Analytical Solutions ◽  
Dynamic Models ◽  
Uncertain Parameters ◽  
Flow Equations ◽  
Practical Applications ◽  
Flow Problems ◽  
Bulk Flow Rate ◽  
Real Time Applications ◽  
And Control

Summary Simplified flow equations are developed for Herschel-Bulkley (HB) fluids in laminar Couette-Poiseuille (CP) flow. Such flow problems are encountered in drilling when the drillstring is moved longitudinally (surge and swab operations). The new equations give the frictional-pressure gradient explicitly as a function of the bulk-flow rate. This makes them very well-suited for applications in fast, robust dynamic models for real-time applications. Incorporating these equations in a dynamic model based on ordinary differential equations (ODEs) enables coupling with system identification and control-system theory. This is a great advantage in drilling applications where there are many uncertain parameters and few measurements. Thorough analysis of relevant analytical solutions is performed to replace the most complex (implicit) parts of the solution with simpler approximations. The accuracy of the new equations, in comparison with numerical simulations and available analytical solutions, is shown to be acceptable for most practical applications.

scholarly journals COLREG-Compliant Optimal Path Planning for Real-Time Guidance and Control of Autonomous Ships

2021 ◽  
Vol 9 (4) ◽  
pp. 405
Author(s):  
Raphael Zaccone
Keyword(s):  
Path Planning ◽  
Real Time ◽  
Collision Avoidance ◽  
Autonomous Navigation ◽  
Optimal Path ◽  
Open Water ◽  
Optimal Path Planning ◽  
Guidance And Control ◽  
Real Time Applications ◽  
And Control

While collisions and groundings still represent the most important source of accidents involving ships, autonomous vessels are a central topic in current research. When dealing with autonomous ships, collision avoidance and compliance with COLREG regulations are major vital points. However, most state-of-the-art literature focuses on offline path optimisation while neglecting many crucial aspects of dealing with real-time applications on vessels. In the framework of the proposed motion-planning, navigation and control architecture, this paper mainly focused on optimal path planning for marine vessels in the perspective of real-time applications. An RRT*-based optimal path-planning algorithm was proposed, and collision avoidance, compliance with COLREG regulations, path feasibility and optimality were discussed in detail. The proposed approach was then implemented and integrated with a guidance and control system. Tests on a high-fidelity simulation platform were carried out to assess the potential benefits brought to autonomous navigation. The tests featured real-time simulation, restricted and open-water navigation and dynamic scenarios with both moving and fixed obstacles.

Real-Time Protocols (RTP/RTCP)

2008 ◽  
pp. 463-468
Author(s):  
Christos Bouras ◽  
Apostolos Gkamas ◽  
Dimitris Primpas ◽  
Kostas Stamos
Keyword(s):  
Real Time ◽  
Packet Loss ◽  
Video On Demand ◽  
Voice Over Ip ◽  
Continuous Data ◽  
Transport Protocols ◽  
On Demand ◽  
Transmission Quality ◽  
Real Time Applications ◽  
And Control

Real-time protocols cover specific needs by applications with real-time characteristics. Real-time applications, such as voice over IP (VoIP), videoconferencing applications, video on demand, continuous data applications, and control and measurement applications have specific requirements from the lower layers, mainly in terms of packet loss, delay, and jitter. Traditional transport protocols such as TCP and UDP have been designed for general use and are not specialized for such specific purposes. In particular, real-time protocols have to be able to deliver high throughput, handle multicast, manage the transmission quality, and be friendly to the rest of the traffic, and, more importantly, to the congestion-sensitive TCP traffic.

UNDERACTUATED HAND DYNAMIC MODELING, ITS REAL-TIME SIMULATION, AND CONTROL

2010 ◽  
Vol 07 (04) ◽  
pp. 609-634 ◽  
Author(s):  
HAI HUANG ◽  
YONG-JIE PANG ◽  
JIANG LI ◽  
SHAO-WEI FAN ◽  
XIN-QING WANG ◽  
...  
Keyword(s):  
Real Time ◽  
Dynamic Model ◽  
Dynamic Models ◽  
Impedance Control ◽  
Differential Algebraic Equations ◽  
Algebraic Equations ◽  
Inverse Dynamic ◽  
Time Dynamic ◽  
Simulation And Control ◽  
And Control

The forward and inverse dynamic models of the underactuated 2-DOF finger have been established in this article based on virtual spring approach. This approach not only avoids the solution of differential-algebraic equations but also leads to a completely decoupled dynamic model that is ideal for directly inverse dynamic analysis, real-time dynamic simulation and control. To verify this approach, an underactuated 3-joint finger has been brought forward. Simulation results from Matlab/Simulink are consistent with those obtained from ADAMS grasp simulations. For the hand real-time dynamic control, the velocity observer has been established based on the dynamic model, the adaptive curve fitting with the observer has obtained precise velocity signals, made up the uncertain parameters such as torsion spring, inertial, damps, etc. and achieved ideal results. By applying dynamics model and observer, the force-based impedance control can realize more accurate and stable force control during grasp.

Microstructural investigation of surface roughness in MBE-grown AlAs

1995 ◽  
Vol 53 ◽  
pp. 454-455
Author(s):  
R. Rajesh ◽  
R. Droopad ◽  
C. H. Kuo ◽  
R. W. Carpenter ◽  
G. N. Maracas
Keyword(s):  
Thin Film ◽  
Real Time ◽  
Growth Control ◽  
Native Oxide ◽  
Effusion Cell ◽  
Surface Oxide Layer ◽  
Microstructural Investigation ◽  
Mbe Growth ◽  
Film Substrate ◽  
And Control

Knowledge of material pseudodielectric functions at MBE growth temperatures is essential for achieving in-situ, real time growth control. This allows us to accurately monitor and control thicknesses of the layers during growth. Undesired effusion cell temperature fluctuations during growth can thus be compensated for in real-time by spectroscopic ellipsometry. The accuracy in determining pseudodielectric functions is increased if one does not require applying a structure model to correct for the presence of an unknown surface layer such as a native oxide. Performing these measurements in an MBE reactor on as-grown material gives us this advantage. Thus, a simple three phase model (vacuum/thin film/substrate) can be used to obtain thin film data without uncertainties arising from a surface oxide layer of unknown composition and temperature dependence.In this study, we obtain the pseudodielectric functions of MBE-grown AlAs from growth temperature (650°C) to room temperature (30°C). The profile of the wavelength-dependent function from the ellipsometry data indicated a rough surface after growth of 0.5 μm of AlAs at a substrate temperature of 600°C, which is typical for MBE-growth of GaAs.

Adaptive Signal Analysis and Interpretation for Real-time Intelligent Patient Monitoring

1994 ◽  
Vol 33 (01) ◽  
pp. 60-63 ◽  
Author(s):  
E. J. Manders ◽  
D. P. Lindstrom ◽  
B. M. Dawant
Keyword(s):  
Computer Architecture ◽  
Real Time ◽  
Data Abstraction ◽  
Monitoring Strategy ◽  
Intelligent Monitoring ◽  
Patient Status ◽  
On Line ◽  
Main Components ◽  
And Control ◽  
Adaptive Signal

Abstract:On-line intelligent monitoring, diagnosis, and control of dynamic systems such as patients in intensive care units necessitates the context-dependent acquisition, processing, analysis, and interpretation of large amounts of possibly noisy and incomplete data. The dynamic nature of the process also requires a continuous evaluation and adaptation of the monitoring strategy to respond to changes both in the monitored patient and in the monitoring equipment. Moreover, real-time constraints may imply data losses, the importance of which has to be minimized. This paper presents a computer architecture designed to accomplish these tasks. Its main components are a model and a data abstraction module. The model provides the system with a monitoring context related to the patient status. The data abstraction module relies on that information to adapt the monitoring strategy and provide the model with the necessary information. This paper focuses on the data abstraction module and its interaction with the model.

Maintaining Consistency Over A Network in Real-Time Applications

1989 ◽  
Author(s):  
Insup Lee ◽  
Susan Davidson ◽  
Victor Wolfe
Keyword(s):  
Real Time ◽  
Real Time Applications
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