A fracture study of slanted cracks using the stress dead‐zone hypothesis

2020 ◽  
Vol 43 (12) ◽  
pp. 3012-3026
Author(s):  
Behzad V. Farahani ◽  
Francisco Q. Melo ◽  
Paulo Tavares ◽  
Pedro Moreira
Keyword(s):  
Dead Zone ◽  
Fracture Study

Global warming could enlarge world’s largest dead zone

2019 ◽  
Author(s):  
Louise Sarant
Keyword(s):  
Global Warming ◽  
Dead Zone

Adaptive tracking of nonlinear time-delay systems subject to symmetrical dead-zone input

2020 ◽  
Author(s):  
Zhenxing Cao ◽  
Xianglei Jia ◽  
Yiming Shao ◽  
Shuo Li
Keyword(s):  
Time Delay ◽  
Dead Zone ◽  
Delay Systems ◽  
Time Delay Systems ◽  
Adaptive Tracking

Membrane structures in the pulp-dentin border zone A freeze-fracture study of demineralized human teeth

1984 ◽  
Vol 42 (2) ◽  
pp. 73-84 ◽  
Author(s):  
Anders Köling ◽  
Helge Rask-andersen
Keyword(s):  
Freeze Fracture ◽  
Border Zone ◽  
Membrane Structures ◽  
Human Teeth ◽  
Fracture Study

An investigation of fine sediment mixing within free-flowing and surcharged manholes

1998 ◽  
Vol 37 (1) ◽  
pp. 215-222
Author(s):  
I. Guymer ◽  
R. O'Brien ◽  
O. Mark ◽  
P. Dennis
Keyword(s):  
Dead Zone ◽  
Laser Induced Fluorescence ◽  
Fine Sediment ◽  
Longitudinal Dispersion ◽  
Qualitative Description ◽  
Suspended Material ◽  
Mixing Processes ◽  
Future Developments ◽  
Mixing Effects ◽  
Sediment Mixing

Previous studies of the effects of manholes on longitudinal dispersion has concentrated on the spreading of solutes. This papers presents new data describing the influence of a surcharged and free-flowing manhole structure on the longitudinal dispersion of a fine suspended material. The effects of benching within the manhole structure are also illustrated. Laser Induced Fluorescence (LIF) techniques have been used to provide a qualitative description of the mixing processes present within a surcharged manhole. Nephelometric results have provided estimates of the parameters required to simulate the mixing effects using either increase in variance or aggregated dead zone techniques. A preliminary attempt at describing these observations using available software is discussed and recommendations for future developments are made.

LIFE IN THE DEAD ZONE: A DIVERSE MIOCENE ICHNOFAUNA PRESERVED IN VOLCANIC ASH, ASHFALL FOSSIL BEDS STATE HISTORICAL PARK, NEBRASKA, USA

2018 ◽  
Author(s):  
Jon J. Smith ◽  
◽  
R.M. Joeckel ◽  
Rick E. Otto ◽  
Shane T. Tucker
Keyword(s):  
Volcanic Ash ◽  
Dead Zone ◽  
The Dead

scholarly journals A Robust Observer—Based Adaptive Control of Second—Order Systems with Input Saturation via Dead-Zone Lyapunov Functions

Computation ◽  
2021 ◽  
Vol 9 (8) ◽  
pp. 82
Author(s):  
Alejandro Rincón ◽  
Gloria M. Restrepo ◽  
Fredy E. Hoyos
Keyword(s):  
Lyapunov Functions ◽  
Dead Zone ◽  
Tracking Error ◽  
Input Saturation ◽  
Chemical Reactor ◽  
Second Order ◽  
Control Law ◽  
Compact Set ◽  
State Variables ◽  
Robust Observer

In this study, a novel robust observer-based adaptive controller was formulated for systems represented by second-order input–output dynamics with unknown second state, and it was applied to concentration tracking in a chemical reactor. By using dead-zone Lyapunov functions and adaptive backstepping method, an improved control law was derived, exhibiting faster response to changes in the output tracking error while avoiding input chattering and providing robustness to uncertain model terms. Moreover, a state observer was formulated for estimating the unknown state. The main contributions with respect to closely related designs are (i) the control law, the update law and the observer equations involve no discontinuous signals; (ii) it is guaranteed that the developed controller leads to the convergence of the tracking error to a compact set whose width is user-defined, and it does not depend on upper bounds of model terms, state variables or disturbances; and (iii) the control law exhibits a fast response to changes in the tracking error, whereas the control effort can be reduced through the controller parameters. Finally, the effectiveness of the developed controller is illustrated by the simulation of concentration tracking in a stirred chemical reactor.

Uniformly ultimately bounded tracking control of sandwich systems with nonsymmetric sandwiched dead-zone nonlinearity and input saturation constraint

2021 ◽  
pp. 107754632098794
Author(s):  
Meysam Azhdari ◽  
Tahereh Binazadeh
Keyword(s):  
Dead Zone ◽  
Input Saturation ◽  
Closed Loop System ◽  
Unknown Parameters ◽  
External Disturbances ◽  
Uniformly Ultimately Bounded ◽  
Output Tracking ◽  
Saturation Constraint ◽  
Two Phases ◽  
Practical Constraints

This article studies the uniformly ultimately bounded output tracking problem of uncertain nonlinear sandwich systems with sandwiched dead-zone nonlinearity in the presence of some practical constraints such as nonsymmetric input saturation, model uncertainties, time-varying external disturbances, and unknown parameters. Due to the existence of both dead-zone and saturation nonlinearities, the design process is more complicated; therefore, to solve the design complexities, the designing process is divided into two phases. The proposed method leads to output tracking with acceptable accuracy. Moreover, all signals in the closed-loop system are ultimately bounded. Simulation results illustrate the applicability and effectiveness of the proposed method by its application on two practical sandwich systems (robotic system and electrohydraulic servo press system).

Adaptive control based on Barrier Lyapunov function for a class of full-state constrained stochastic nonlinear systems with dead-zone and unmodeled dynamics

2021 ◽  
pp. 014233122098563
Author(s):  
Fei Shen ◽  
Xinjun Wang ◽  
Xinghui Yin
Keyword(s):  
Adaptive Control ◽  
Nonlinear Systems ◽  
Lyapunov Function ◽  
Dead Zone ◽  
Small Neighborhood ◽  
Unmodeled Dynamics ◽  
Stochastic Nonlinear Systems ◽  
Dynamic Surface ◽  
Barrier Lyapunov Function ◽  
Full State

This paper investigates the problem of adaptive control based on Barrier Lyapunov function for a class of full-state constrained stochastic nonlinear systems with dead-zone and unmodeled dynamics. To stabilize such a system, a dynamic signal is introduced to dominate unmodeled dynamics and an assistant signal is constructed to compensate for the effect of the dead zone. Dynamic surface control is used to solve the “complexity explosion” problem in traditional backstepping design. Two cases of symmetric and asymmetric Barrier Lyapunov functions are discussed respectively in this paper. The proposed Barrier Lyapunov function based on backstepping method can ensure that the output tracking error converges in the small neighborhood of the origin. This control scheme can ensure that semi-globally uniformly ultimately boundedness of all signals in the closed-loop system. Two simulation cases are proposed to verify the effectiveness of the theoretical method.

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