scholarly journals Fluctuation-induced distributed resonances in oscillatory networks

2019 ◽  
Vol 5 (7) ◽  
pp. eaav1027 ◽  
Author(s):  
Xiaozhu Zhang ◽  
Sarah Hallerberg ◽  
Moritz Matthiae ◽  
Dirk Witthaut ◽  
Marc Timme
Keyword(s):  
Dynamic Network ◽  
Intermediate Frequency ◽  
Response Patterns ◽  
Low Frequencies ◽  
High Frequencies ◽  
Self Organized ◽  
Oscillatory Networks ◽  
Input Signals ◽  
Induce Response ◽  
And Control

Across physics, biology, and engineering, the collective dynamics of oscillatory networks often evolve into self-organized operating states. How such networks respond to external fluctuating signals fundamentally underlies their function, yet is not well understood. Here, we present a theory of dynamic network response patterns and reveal how distributed resonance patterns emerge in oscillatory networks once the dynamics of the oscillatory units become more than one-dimensional. The network resonances are topology specific and emerge at an intermediate frequency content of the input signals, between global yet homogeneous responses at low frequencies and localized responses at high frequencies. Our analysis reveals why these patterns arise and where in the network they are most prominent. These results may thus provide general theoretical insights into how fluctuating signals induce response patterns in networked systems and simultaneously help to develop practical guiding principles for real-world network design and control.

Pre-Stall Waves: Precursors to Stall Inception in a Contra-Rotating Axial Fan

2020 ◽  
Author(s):  
Manas Madasseri Payyappalli ◽  
A. M. Pradeep
Keyword(s):  
Low Frequency ◽  
Intermediate Frequency ◽  
Axial Fan ◽  
Frequency Spectra ◽  
Low Frequencies ◽  
Stall Inception ◽  
High Frequencies ◽  
Inflow Condition ◽  
Design Speed ◽  
High Frequency Waves

Abstract Stall in a compressor or a fan is often associated with pre-stall waves, that could act as precursors. The present study aims to understand in detail the pre-stall waves leading to instabilities in a low aspect ratio, low hub-tip ratio contra-rotating axial fan. Apart from a clean inflow condition, experiments on the contra-rotating fan are also carried out for two radial distortion conditions, namely, hub-radial and tip-radial distortions, and three circumferential distortion conditions, namely, simple-circumferential, hub-complex-circumferential and tip-complex-circumferential distortions. The results primarily concluded that operating rotor-2 at a speed higher than the design speed could possibly suppress the pre-stall disturbances. Towards the fully developed stall, the waves that are associated with low frequencies speed up and thus these waves become intermediate frequency waves. The fluid phenomena that trigger the stall are associated with high frequencies and these subsequently stretch to low frequencies at the onset of fully developed stall. The low-frequency waves and high frequency waves compromise to reach an intermediate frequency range during the fully developed stall. Further, it is observed that disturbances associated with low frequencies as well as high frequencies co-exist during the fully developed stall regime. There is also a region in the frequency spectra where no disturbances are excited and this region appears to be a “no excitation zone”. This paper thus concludes that there possibly exists a mechanism through which the energy is transferred between different frequencies during the pre-stall and fully developed stall regimes.

scholarly journals The Next Normal for Marketing — The Dynamics of a Pandemic, Provisioning Systems, and the Changing Patterns of Daily Life

2021 ◽  
Vol 29 (1) ◽  
pp. 4-14
Author(s):  
Roger A. Layton ◽  
Christine Domegan
Keyword(s):  
Daily Life ◽  
Social Mechanisms ◽  
Individual Values ◽  
Public And Private ◽  
Supply Networks ◽  
Edge Of Chaos ◽  
Self Organized ◽  
Changing Patterns ◽  
Multi Level ◽  
And Control

Pandemics, climate warming, growing inequality, and much more bring crises that change the patterns of daily life in human communities, directly impacting the provisioning systems that form in a community to meet the needs and wants of individuals, groups, and entities for goods, services, experiences, ideas. Provisioning systems sometimes begin as leadership initiated top-down, authoritarian prescriptive supply networks, public and private. Sometimes, they originate as bottom-up, self-organized, innovative, open choice, often informal, exchange based networks, and mostly, over time, they emerge as untidy self-organized multi-level diverse assemblages of both. The diversity of provisioning systems in a community enables crisis resilience, but limits efficiency and control. The provisioning systems that form in these ways are complex, multi-level, non-linear evolutionary systems, often unpredictable, and lacking direction. Balancing a desire for stability and an appetite for diversity, innovation, and change in shaping a provisioning system is like walking a narrow corridor on the edge of chaos. Achieving balance, avoiding slipping into chaos, rests on the management of a set of complex social mechanisms. These embrace delivery mechanisms where value is produced and consumed through complex infrastructures; stakeholder action fields where trust, collaboration, cooperation, compromise, competition, or conflict are in play; technology evolution mechanisms where innovation and the recombination of existing technologies occur at all levels; and value exchange fields where community and individual values shift in response to crisis and change. Recovery from crisis is not an event, it is a complex, continuing process, often unpredictable, often unequal in outcomes, but walking a narrow corridor is episodic, uncertain and in the end possible. This is the next normal for marketing.

scholarly journals Self-Organized Crowd Dynamics: Research on Earthquake Emergency Response Patterns of Drill-Trained Individuals Based on GIS and Multi-Agent Systems Methodology

Sensors ◽  
2021 ◽  
Vol 21 (4) ◽  
pp. 1353
Author(s):  
Hai Sun ◽  
Lanling Hu ◽  
Wenchi Shou ◽  
Jun Wang
Keyword(s):  
Quantitative Relation ◽  
Response Patterns ◽  
Multi Agent Systems ◽  
Systems Methodology ◽  
Cellular Automata Model ◽  
Self Organized ◽  
Multi Agent ◽  
Exit Choice ◽  
Evacuation Plan ◽  
Exit Options

Predicting evacuation patterns is useful in emergency management situations such as an earthquake. To find out how pre-trained individuals interact with one another to achieve their own goal to reach the exit as fast as possible firstly, we investigated urban people’s evacuation behavior under earthquake disaster coditions, established crowd response rules in emergencies, and described the drill strategy and exit familiarity quantitatively through a cellular automata model. By setting different exit familiarity ratios, simulation experiments under different strategies were conducted to predict people’s reactions before an emergency. The corresponding simulation results indicated that the evacuees’ training level could affect a multi-exit zone’s evacuation pattern and clearance time. Their exit choice preferences may disrupt the exit options’ balance, leading to congestion in some of the exits. Secondly, due to people’s rejection of long distances, congestion, and unfamiliar exits, some people would hesitant about the evacuation direction during the evacuation process. This hesitation would also significantly reduce the overall evacuation efficiency. Finally, taking a community in Zhuhai City, China, as an example, put forward the best urban evacuation drill strategy. The quantitative relation between exit familiar level and evacuation efficiency was obtained. The final results showed that the optimized evacuation plan could improve evacuation’s overall efficiency through the self-organization effect. These studies may have some impact on predicting crowd behavior during evacuation and designing the evacuation plan.

Effect of Blowing Agent on Cell Morphology and Acoustic Absorption of Natural Rubber Foam

2015 ◽  
Vol 804 ◽  
pp. 25-29 ◽  
Author(s):  
Wanlop Harnnarongchai ◽  
Kantima Chaochanchaikul
Keyword(s):  
Natural Rubber ◽  
Cell Size ◽  
Cell Morphology ◽  
Foam Cell ◽  
Adsorption Coefficient ◽  
Low Frequencies ◽  
Potassium Oleate ◽  
High Frequencies ◽  
Blowing Agent ◽  
Open Cell Foam

The sound absorbing efficiency of natural rubber (NR) foam is affected by the cell morphology of foam. Potassium oleate (K-oleate) and sodium bicarbonate (NaHCO3) were used as blowing agents to create open-cell foam. Amounts of the blowing agent were varied from 0.5 to 8.0 part per hundred of rubber (phr) to evaluate cell size and number of foam cell as well as sound adsorption coefficient of NR foam. The NR foam specimens were prepared using mould and air-circulating oven for vulcanizing and foaming processes. The results indicated that K-oleate at 2.0 phr and NaHCO3 at 0.5 phr led to form NR foam with the smallest cell size and the largest number of foam cell. At low frequencies, the optimum sound adsorption coefficient of NR foam was caused by filling K-oleate 2 phr. However, that of NR foam at high frequencies was provided by 0.5 phr-NaHCO3 addition.

Comparison of electromyographic response patterns during posture and stress tasks in chronic low back pain patterns and control

1986 ◽  
Vol 30 (2) ◽  
pp. 135-141 ◽  
Author(s):  
Michael J. Cohen ◽  
Gretchen A. Swanson ◽  
Bruce D. Naliboff ◽  
Steven L. Schandler ◽  
David L. McArthur
Keyword(s):  
Low Back Pain ◽  
Back Pain ◽  
Chronic Low Back Pain ◽  
Low Back ◽  
Response Patterns ◽  
And Control

Hearing loss in diabetics

1993 ◽  
Vol 107 (3) ◽  
pp. 179-182 ◽  
Author(s):  
J. R. Cullen ◽  
M. J. Cinnamond
Keyword(s):  
Hearing Loss ◽  
Sensorineural Deafness ◽  
Insulin Dosage ◽  
Speech Discrimination ◽  
Low Frequencies ◽  
High Frequencies ◽  
History Of ◽  
Insulin Dependent ◽  
Stapedial Reflex ◽  
The Relationship

The relationship between diabetes and senbsorineural hearing loss has been disputed. This study compares 44 insulin-dependent diabetics with 38 age and sex matched controls. All had pure tone and speech audiometry performed, with any diabetics showing sensorineural deafness undergoing stapedial reflecx decat tests. In 14 diabetics stapedial reflex tests showed no tone decay in any patient, but seven showed evidence of recruitment. Analysis of vaiance showed the diabetics to be significantly deafer than the control population.The hearing loss affected high frequencies in both sexes, but also low frequencies in the male. Speech discrimination scores showed no differences. Further analysis by sex showed the males to account for most of the differences. Analysys of the audiograms showered mostly a high tone loss. Finally duration of disbetes, insulin dosage and family history of diabtes were not found to have a significant effect on threshold.

The Application of the Amorphous Metal Transformers in Heavy Oil Electric Heating System

2014 ◽  
Vol 532 ◽  
pp. 191-195 ◽  
Author(s):  
Bao Jiang Sun ◽  
Lei Su ◽  
Chao Zhang
Keyword(s):  
Electric Heating ◽  
Heating System ◽  
Intermediate Frequency ◽  
Amorphous Metal ◽  
Technical Performance ◽  
Alloy Material ◽  
Working Principle ◽  
The Stability ◽  
And Control ◽  
Fast Rise

In order to solve the problem that the big loss of no-load and the fast rise of temperature when employ the conventional silicon steel metal transformer (SSMT) in the electric heating system, we choose the amorphous metal transformer (AMMT). In this paper, firstly, we give a brief introduction of the amorphous alloy material properties and compare the no-load characteristic of the AMMT with the SSMT. Secondly, the structure of intermediate frequency heating system working principle and control strategy are introduced. Finally, extensive experiments were conducted to validate the ideas. The experiments show that the AMMT not only improve the efficiency of transformer, solve the heating problem of transformer, but also improve the stability, security and other technical performance of the system, so it is worth recommending and promoting.

Use of Measured Mobility to Improve SEA Predictions in the Mid-Frequency Range

1999 ◽  
Author(s):  
Jerome E. Manning
Keyword(s):  
Dynamic Systems ◽  
Broad Band ◽  
Measured Data ◽  
Hybrid Technique ◽  
Complex Dynamic ◽  
Low Frequencies ◽  
Large Variability ◽  
High Frequencies ◽  
Complex Dynamic Systems ◽  
Light Coupling

Abstract Statistical energy analysis provides a technique to predict acoustic and vibration levels in complex dynamic systems. The technique is most useful for broad-band excitation at high frequencies where many modes contribute to the response in any given frequency band. At mid and low frequencies, the number of modes contributing to the response may be quite small. In this case SEA predictions show large variability from measured data and may not be useful for vibroacoustic design. This paper focuses on the use of measured data to improve the accuracy of the predictions. Past work to measure the SEA coupling and damping loss factors has not been successful for a broad range of systems that do not have light coupling. This paper introduces a new hybrid SEA technique that combines measured mobility functions with analytical SEA predictions. The accuracy of the hybrid technique is shown to be greatly improved at mid and low frequencies.

Frequency-Weighted Variable-Length Controllers Using Anytime Control Strategies

2011 ◽  
Author(s):  
Gundula B. Runge ◽  
Al Ferri ◽  
Bonnie Ferri
Keyword(s):  
Time Scale ◽  
Weighting Function ◽  
Control Strategies ◽  
Low Frequency ◽  
Low Frequencies ◽  
High Frequencies ◽  
Frequency Components ◽  
Computational Resources ◽  
Weighted Variable ◽  
Selection Of

This paper considers an anytime strategy to implement controllers that react to changing computational resources. The anytime controllers developed in this paper are suitable for cases when the time scale of switching is in the order of the task execution time, that is, on the time scale found commonly with sporadically missed deadlines. This paper extends the prior work by developing frequency-weighted anytime controllers. The selection of the weighting function is driven by the expectation of the situations that would require anytime operation. For example, if the anytime operation is due to occasional and isolated missed deadlines, then the weighting on high frequencies should be larger than that for low frequencies. Low frequency components will have a smaller change over one sample time, so failing to update these components for one sample period will have less effect than with the high frequency components. An example will be included that applies the anytime control strategy to a model of a DC motor with deadzone and saturation nonlinearities.

Sign in / Sign up

Export Citation Format

Share Document