scholarly journals How Does the Air‐Sea Coupling Frequency Affect Convection During the MJO Passage?

2020 ◽  
Vol 12 (4) ◽  
Author(s):  
Ning Zhao ◽  
Tomoe Nasuno
Keyword(s):  
Coupling Frequency

scholarly journals The Impact of Finer-Resolution Air–Sea Coupling on the Intraseasonal Oscillation of the Indian Monsoon

2011 ◽  
Vol 24 (10) ◽  
pp. 2451-2468 ◽  
Author(s):  
Nicholas P. Klingaman ◽  
Steven J. Woolnough ◽  
Hilary Weller ◽  
Julia M. Slingo
Keyword(s):  
Atmospheric Stability ◽  
Intraseasonal Oscillation ◽  
Boreal Summer ◽  
Upper Ocean ◽  
Vertical Resolution ◽  
Coupled Models ◽  
Diurnal Variability ◽  
Near Surface ◽  
The Impact ◽  
Coupling Frequency

Abstract A newly assembled atmosphere–ocean coupled model, called HadKPP, is described and then used to determine the effects of subdaily air–sea coupling and fine near-surface ocean vertical resolution on the representation of the Northern Hemisphere summer intraseasonal oscillation. HadKPP comprises the Hadley Centre atmospheric model coupled to the K-Profile Parameterization ocean boundary layer model. Four 30-member ensembles were performed that vary in ocean vertical resolution between 1 and 10 m and in coupling frequency between 3 and 24 h. The 10-m, 24-h ensemble exhibited roughly 60% of the observed 30–50-day variability in sea surface temperatures and rainfall and very weak northward propagation. Enhancing only the vertical resolution or only the coupling frequency produced modest improvements in variability and just a standing intraseasonal oscillation. Only the 1-m, 3-h configuration generated organized, northward-propagating convection similar to observations. Subdaily surface forcing produced stronger upper-ocean temperature anomalies in quadrature with anomalous convection, which likely affected lower-atmospheric stability ahead of the convection, causing propagation. Well-resolved air–sea coupling did not improve the eastward propagation of the boreal summer intraseasonal oscillation in this model. Upper-ocean vertical mixing and diurnal variability in coupled models must be improved to accurately resolve and simulate tropical subseasonal variability. In HadKPP, the mere presence of air–sea coupling was not sufficient to generate an intraseasonal oscillation resembling observations.

scholarly journals Study on the Coupling Frequency of Double-Sided Submerged Ring-Stiffened Cylindrical Shells

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Anbin Yu ◽  
Yinglong Zhao ◽  
Youqian Wang ◽  
Ben Zhang
Keyword(s):  
Cylindrical Shell ◽  
Free Surface ◽  
Hydrostatic Pressure ◽  
Water Immersion ◽  
Theoretical Method ◽  
Coupling Model ◽  
Acoustic Vibration ◽  
Stiffened Cylindrical Shell ◽  
Calculation Results ◽  
Coupling Frequency

Based on the Flügge theory and orthotropic theory, the acoustic vibration coupling model of ring-stiffened cylindrical shell is established by using the wave propagation method and virtual source method. And the effects of water immersion on both sides, free surface, and hydrostatic pressure on the cylindrical shell are considered in the coupling model. Muller three-point iterative method is used to solve the coupling frequency. The calculation results of degradation theory are compared with COMSOL’s calculation results and experimental results, respectively, which verifies the reliability of the theoretical method. Finally, the influence of fluid load, ring rib parameters, boundary conditions, hydrostatic pressure, and free surface on the coupled vibration of ring-stiffened cylindrical shell is analyzed by an example.

A novel motion coupling coding method for brain-computer interfaces

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Wenqiang Yan ◽  
Guanghua Xu
Keyword(s):  
Steady State ◽  
Visual Evoked Potential ◽  
Evoked Potential ◽  
Frequency Component ◽  
Wave Form ◽  
Square Wave ◽  
Computer Interfaces ◽  
Coding Method ◽  
Coupling Frequency ◽  
Visual Evoked

AbstractObjectivesThe best frequency response band for the steady-state visual evoked potential (SSVEP) stimulus for humans is limited. This results in a reduced number of encoded targets.MethodsTo circumvent these limitations, we propose a motion-coupled, steady-state motion visual evoked potential (SSMVEP) method. We designed a stimulus paradigm that couples both sinusoidal and square wave motions. The paradigm performs a spiral motion with a higher frequency in the form of sinusoidal wave, and alters the size of the lower frequency via the square wave form.ResultsThe motion-coupled SSMVEP method could simultaneously induce stable motion frequency and coupling frequency, and there was no loss of frequency component.ConclusionsThe proposed method has been evaluated to have substantial potential for increasing the number of coding targets, which is an effective supplement to the existing studies.

scholarly journals Efficiency and Frequency of Translational Coupling between the Bacteriophage T4 Clamp Loader Genes

1998 ◽  
Vol 180 (17) ◽  
pp. 4339-4343 ◽  
Author(s):  
Michael Y. Torgov ◽  
Deanna M. Janzen ◽  
Michael K. Reddy
Keyword(s):  
Bacteriophage T4 ◽  
Coupling Efficiency ◽  
Clamp Loader ◽  
Translational Coupling ◽  
Polycistronic Mrna ◽  
Sliding Clamp ◽  
Absolute Requirement ◽  
Replication Systems ◽  
Coupling Frequency

ABSTRACT The bacteriophage T4 DNA polymerase holoenzyme is composed of the core polymerase, gene product 43 (gp43), in association with the “sliding clamp” of the T4 system, gp45. Sliding clamps are the processivity factors of DNA replication systems. The T4 sliding clamp comes to encircle DNA via the “clamp loader” activity inherent in two other T4 proteins: 44 and 62. These proteins assemble into a pentameric complex with a precise 4:1 stoichiometry of proteins 44 and 62. Previous work established that T4 genes 44 and62, which are directly adjacent on polycistronic mRNA molecules, are—to some degree—translationally coupled. In the present study, measurement of the levels (monomers/cell) of the clamp loader subunits during the course of various T4 infections in different host cell backgrounds was accomplished by quantitative immunoblotting. The efficiency of translational coupling was obtained by determining the in vivo levels of gp62 that were synthesized when its translation was either coupled to or uncoupled from the upstream translation of gene 44. Levels of gp44 were also measured to determine the relative stoichiometry of synthesis and the percentage of gp44 translation that was transmitted across the intercistronic junction (coupling frequency). The results indicated a coupling efficiency of ∼85% and a coupling frequency of ∼25% between the44-62 gene pair during the course of infection. Thus, translational coupling is the major factor in maintaining the 4:1 stoichiometry of synthesis of the clamp loader subunits. However, coupling does not appear to be an absolute requirement for the synthesis of gp62.

scholarly journals Tropical Cyclone Interaction with the Ocean: The Role of High-Frequency (Subdaily) Coupled Processes

2017 ◽  
Vol 30 (1) ◽  
pp. 145-162 ◽  
Author(s):  
Enrico Scoccimarro ◽  
Pier Giuseppe Fogli ◽  
Kevin A. Reed ◽  
Silvio Gualdi ◽  
Simona Masina ◽  
...  
Keyword(s):  
Tropical Cyclone ◽  
High Frequency ◽  
Climate Model ◽  
Horizontal Resolution ◽  
Coupled Processes ◽  
Realistic Representation ◽  
Order Of Magnitude ◽  
The Impact ◽  
Coupling Frequency

Through tropical cyclone (TC) activity the ocean and the atmosphere exchange a large amount of energy. In this work possible improvements introduced by a higher coupling frequency are tested between the two components of a climate model in the representation of TC intensity and TC–ocean feedbacks. The analysis is based on the new Centro Euro-Mediterraneo per I Cambiamenti Climatici Climate Model (CMCC-CM2-VHR), capable of representing realistic TCs up to category-5 storms. A significant role of the negative sea surface temperature (SST) feedback, leading to a weakening of the cyclone intensity, is made apparent by the improved representation of high-frequency coupled processes. The first part of this study demonstrates that a more realistic representation of strong TC count is obtained by coupling atmosphere and ocean components at hourly instead of daily frequency. Coherently, the positive bias of the annually averaged power dissipation index associated with TCs is reduced by one order of magnitude when coupling at the hourly frequency, compared to both forced mode and daily coupling frequency results. The second part of this work shows a case study (a modeled category-5 typhoon) analysis to verify the impact of a more realistic representation of the high-frequency coupling in representing the TC effect on the ocean; the theoretical subsurface warming induced by TCs is well represented when coupling the two components at the higher frequency. This work demonstrates that an increased horizontal resolution of model components is not sufficient to ensure a realistic representation of intense and fast-moving systems, such as tropical and extratropical cyclones, but a concurrent increase in coupling frequency is required.

Development of Low-Loss (Bi,Pb)-2223 Tapes with Interfilamentary Resistive Barriers

2010 ◽  
Vol 75 ◽  
pp. 181-186 ◽  
Author(s):  
Ryoji Inada ◽  
Akio Oota ◽  
Cheng Shan Li ◽  
Ping Xiang Zhang
Keyword(s):  
Critical Current ◽  
Side Effect ◽  
Cold Working ◽  
Low Loss ◽  
Barrier Materials ◽  
Current Densities ◽  
Perpendicular Field ◽  
Fully Coupled ◽  
Coupling Frequency ◽  
K Transport

This paper presents our recent activities for the development of low-loss (Bi,Pb)-2223 tapes with interfilamentary resistive barriers. To suppress the side effect on the phase formation in the filaments during sintering, SrZrO3 were selected as barrier materials. Moreover, small amount of Bi-2212 was mixed with SrZrO3 to improve their ductility for cold working. For non-twisted barrier tapes, transport critical current densities Jc at 77 K and self-field were ranged between 18 and 21 kA/cm2 and its uniformity within 4% along a 1 m length. By combining the barrier introduction, reducing the tape width (< 3 mm) and twisting the filaments tightly, coupling frequency fc exceeded 250 Hz even in an AC perpendicular field at 77 K. Transport Jc of the barrier tapes with tightly twisted filaments were in the range of 1214 kA/cm2 at 77 K and self-field. In our knowledge, this is the first result to achieve both Jc > 12 kA/cm2 and fc > 250 Hz simultaneously in an isolated (Bi,Pb)-2223 tape. At 50 mT and 50 Hz, our twisted barrier tapes showed 60-70% lower perpendicular field losses than a conventional 4 mm-width tape with fully coupled filaments.

Mechanism of frequency lock-in in transonic buffeting flow

2017 ◽  
Vol 818 ◽  
pp. 528-561 ◽  
Author(s):  
Chuanqiang Gao ◽  
Weiwei Zhang ◽  
Xintao Li ◽  
Yilang Liu ◽  
Jingge Quan ◽  
...  
Keyword(s):  
Natural Frequency ◽  
Physical Mechanism ◽  
Degree Of Freedom ◽  
Navier Stokes ◽  
Complex Eigenvalue ◽  
Abnormal Phenomenon ◽  
Complex Eigenvalue Analysis ◽  
Lock In ◽  
Structural Mode ◽  
Coupling Frequency

Frequency lock-in can occur on a spring suspended airfoil in transonic buffeting flow, in which the coupling frequency does not follow the buffet frequency but locks onto the natural frequency of the elastic airfoil. Most researchers have attributed this abnormal phenomenon to resonance. However, this interpretation failed to reveal the root cause. In this paper, the physical mechanism of frequency lock-in is studied by a linear dynamic model, combined with the coupled computational fluid dynamics/computational structural dynamics (CFD/CSD) simulation. We build a reduced-order model of the flow using the identification method and unsteady Reynolds-averaged Navier–Stokes computations in a post-buffet state. A linear aeroelastic model is then obtained by coupling this model with a degree-of-freedom equation for the pitching motion. Results from the complex eigenvalue analysis indicate that the coupling between the structural mode and the fluid mode leads to the instability of the structural mode. The instability range coincides with the lock-in region obtained by the coupled CFD/CSD simulation. Therefore, the physical mechanism underlying frequency lock-in is caused by the linear coupled-mode flutter – the coupling between one structural mode and one fluid mode. This is different from the classical single-degree-of-freedom flutter (e.g. transonic buzz), which occurs in stable flows; the present flutter is in the unstable buffet flow. The response of the airfoil system undergoes a conversion from forced vibration to self-sustained flutter. The coupling frequency certainly should lock onto the natural frequency of the elastic airfoil.

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