Timing simulator by waveform relaxation considering the feedback effect

1989 ◽  
Vol 136 (1) ◽  
pp. 38 ◽  
Author(s):  
Y.-H. Jun ◽  
C.-W. Lee ◽  
K.-J. Lee ◽  
S.-B. Park
Keyword(s):  
Feedback Effect ◽  
Waveform Relaxation

Synchronization of Chaotic Quantum Dot Light Emitting Diodes under Optical Feedback Effect

2020 ◽  
pp. 144-148
Keyword(s):  
Quantum Dot ◽  
Delay Time ◽  
Chaos Synchronization ◽  
Optical Feedback ◽  
Light Emitting Diode ◽  
Feedback Effect ◽  
Complete Synchronization ◽  
Light Emitting ◽  
Coupling Methods ◽  
Coupling Parameters

Chaos synchronization of delayed quantum dot light emitting diode has been studied theortetically which are coupled via the unidirectional and bidirectional. at synchronization of chaotic, The dynamics is identical with delayed optical feedback for those coupling methods. Depending on the coupling parameters and delay time the system exhibits complete synchronization, . Under proper conditions, the receiver quantum dot light emitting diode can be satisfactorily synchronized with the transmitter quantum dot light emitting diode due to the optical feedback effect.

scholarly journals Spatio-Temporal Variation Characteristics of Snow Depth and Snow Cover Days over the Tibetan Plateau

Water ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 307
Author(s):  
Chi Zhang ◽  
Naixia Mou ◽  
Jiqiang Niu ◽  
Lingxian Zhang ◽  
Feng Liu
Keyword(s):  
Tibetan Plateau ◽  
Snow Cover ◽  
Snow Depth ◽  
Feedback Effect ◽  
Effect Of Temperature ◽  
The Tibetan Plateau ◽  
Reanalysis Dataset ◽  
Spatio Temporal ◽  
The Impact ◽  
Main Factor

Changes in snow cover over the Tibetan Plateau (TP) have a significant impact on agriculture, hydrology, and ecological environment of surrounding areas. This study investigates the spatio-temporal pattern of snow depth (SD) and snow cover days (SCD), as well as the impact of temperature and precipitation on snow cover over TP from 1979 to 2018 by using the ERA5 reanalysis dataset, and uses the Mann–Kendall test for significance. The results indicate that (1) the average annual SD and SCD in the southern and western edge areas of TP are relatively high, reaching 10 cm and 120 d or more, respectively. (2) In the past 40 years, SD (s = 0.04 cm decade−1, p = 0.81) and SCD (s = −2.3 d decade−1, p = 0.10) over TP did not change significantly. (3) The positive feedback effect of precipitation is the main factor affecting SD, while the negative feedback effect of temperature is the main factor affecting SCD. This study improves the understanding of snow cover change and is conducive to the further study of climate change on TP.

Increased space-parallelism via time-simultaneous Newton-multigrid methods for nonstationary nonlinear PDE problems

2021 ◽  
Vol 35 (3) ◽  
pp. 211-225
Author(s):  
Jonas Dünnebacke ◽  
Stefan Turek ◽  
Christoph Lohmann ◽  
Andriy Sokolov ◽  
Peter Zajac
Keyword(s):  
Krylov Subspace ◽  
Solution Procedure ◽  
Grid Size ◽  
Waveform Relaxation ◽  
Test Problems ◽  
Subspace Method ◽  
Multigrid Algorithm ◽  
Multigrid Solvers ◽  
Large Systems ◽  
Linear Pdes

We discuss how “parallel-in-space & simultaneous-in-time” Newton-multigrid approaches can be designed which improve the scaling behavior of the spatial parallelism by reducing the latency costs. The idea is to solve many time steps at once and therefore solving fewer but larger systems. These large systems are reordered and interpreted as a space-only problem leading to multigrid algorithm with semi-coarsening in space and line smoothing in time direction. The smoother is further improved by embedding it as a preconditioner in a Krylov subspace method. As a prototypical application, we concentrate on scalar partial differential equations (PDEs) with up to many thousands of time steps which are discretized in time, resp., space by finite difference, resp., finite element methods. For linear PDEs, the resulting method is closely related to multigrid waveform relaxation and its theoretical framework. In our parabolic test problems the numerical behavior of this multigrid approach is robust w.r.t. the spatial and temporal grid size and the number of simultaneously treated time steps. Moreover, we illustrate how corresponding time-simultaneous fixed-point and Newton-type solvers can be derived for nonlinear nonstationary problems that require the described solution of linearized problems in each outer nonlinear step. As the main result, we are able to generate much larger problem sizes to be treated by a large number of cores so that the combination of the robustly scaling multigrid solvers together with a larger degree of parallelism allows a faster solution procedure for nonstationary problems.

EFFECT OF HYPOTHALAMIC DEAFFERENTATION ON THE CONTROL OF LUTEINIZING HORMONE SECRETION

1970 ◽  
Vol 46 (1) ◽  
pp. 1-7 ◽  
Author(s):  
S. TALEISNIK ◽  
M. E. VELASCO ◽  
J. J. ASTRADA
Keyword(s):  
Luteinizing Hormone ◽  
Negative Feedback ◽  
Positive Feedback ◽  
Hormone Secretion ◽  
Feedback Effect ◽  
Luteinizing Hormone Secretion ◽  
Ovarian Steroids ◽  
Medial Hypothalamus ◽  
Lh Release ◽  
Positive Feedback Effect

SUMMARY The influence that the interruption of the neural afferents to the hypothalamus exerts on ovulation and on the release of luteinizing hormone (LH) was studied in the rat. Animals with retrochiasmatic sections interrupting the neural connexions between the medial hypothalamus and the preoptic area (POA) showed constant oestrus and failed to ovulate. Animals in which the dorsal neural afferents to the POA were transected had oestrous cycles and ovulated normally. The positive feedback effect of progesterone on LH release in spayed animals primed either with 20 μg. oestradiol benzoate or 2·5 mg. testosterone propionate 3 days before was studied. Transection of the dorsal afferents to the POA favoured an increase in plasma LH, but in animals with retrochiasmatic sections the response was abolished. However, the negative feedback effect of ovarian steroids operated after both types of transection because an increase in plasma LH occurred after ovariectomy. It is concluded that the negative feedback effect of ovarian steroids acts on the medial hypothalamus which can maintain a tonic release of gonadotrophins in the absence of steroids. In contrast, the POA involved in the positive feedback effect of progesterone is concerned with the phasic release of LH.

scholarly journals An Initialization Technique for the Waveform-Relaxation Circuit Simulation

VLSI Design ◽  
1999 ◽  
Vol 9 (2) ◽  
pp. 213-218 ◽  
Author(s):  
S. E.-D. Habib ◽  
G. J. Al-Karim
Keyword(s):  
Circuit Simulation ◽  
Waveform Relaxation ◽  
Synchronous Circuits ◽  
Highly Effective ◽  
Initialization Scheme

This paper reports the development of the Cairo University Waveform Relaxation (CUWORX) simulator. In order to accelerate the convergence of the waveform relaxation (WR) in the presence of logic feedback, CUWORK is initialized via a logic simulator. This logic initialization scheme is shown to be highly effective for digital synchronous circuits. Additionally, this logic initialization scheme preserves fully the multi-rate properties of the WR algorithm.

Sign in / Sign up

Export Citation Format

Share Document