Calculation of Vibration Resistance of a Chemical Reactor High-Speed Shaft Undergoing Torsional Vibrations. Part I. Development of a Block Diagram and a Dynamic Transmission Model

Manual transmission gear rattle is the result of repetitive impacts of gear meshing teeth within their backlash. This NVH phenomenon is a major industrial concern and can occur under various loaded or unloaded conditions. It fundamentally differs from other transient NVH phenomena, such as clonk or thud, which are due to impulsive actions. However, they all have their lowest common denominator in the action of contact/impact forces through lubricated contacts. Various forms of rattle have, therefore, been defined: idle rattle, drive rattle, creep rattle and over-run rattle. This paper presents a dynamic transmission model for creep rattle conditions (engaged gear at low engine RPM). The model takes into account the lubricated impact force between a gear teeth pair during a meshing cycle as well as the friction between their flanks. Hertzian contact conditions are applied to the gear pair along the torque path. Additionally, isoviscous hydrodynamic regime of lubrication is assumed for unselected (loose gear pairs) with lightly loaded impact conditions. The highly non-linear impacts induce a range of system response frequencies. These include engine order harmonics, harmonics of meshing frequency and natural frequencies related to contact stiffness. The last of these are dependent on the contact geometry and lubricant rheology. The analysis includes lubricant viscosity variation due to generated contact pressures as well as temperature. For loose gears, subject to oscillations on their retaining bearings, bearing friction is also considered.

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The incremental burden of invasive pneumococcal disease associated with a decline in childhood vaccination using a dynamic transmission model in Japan: A secondary impact of COVID-19

Computers in Biology and Medicine ◽

10.1016/j.compbiomed.2021.104429 ◽

2021 ◽

Vol 133 ◽

pp. 104429

Author(s):

Taito Kitano ◽

Hirosato Aoki

Keyword(s):

Invasive Pneumococcal Disease ◽

Pneumococcal Disease ◽

Childhood Vaccination ◽

Transmission Model ◽

Secondary Impact ◽

Dynamic Transmission Model

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Estimated transmissibility and impact of SARS-CoV-2 lineage B.1.1.7 in England

Science ◽

10.1126/science.abg3055 ◽

2021 ◽

Vol 372 (6538) ◽

pp. eabg3055 ◽

Cited By ~ 82

Author(s):

Nicholas G. Davies ◽

Sam Abbott ◽

Rosanna C. Barnard ◽

Christopher I. Jarvis ◽

Adam J. Kucharski ◽

...

Keyword(s):

United States ◽

Severe Acute Respiratory Syndrome ◽

Reproduction Number ◽

The United States ◽

Control Measures ◽

Transmission Model ◽

Educational Institutions ◽

Stringent Control ◽

Dynamic Transmission Model ◽

Credible Intervals

A severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variant, VOC 202012/01 (lineage B.1.1.7), emerged in southeast England in September 2020 and is rapidly spreading toward fixation. Using a variety of statistical and dynamic modeling approaches, we estimate that this variant has a 43 to 90% (range of 95% credible intervals, 38 to 130%) higher reproduction number than preexisting variants. A fitted two-strain dynamic transmission model shows that VOC 202012/01 will lead to large resurgences of COVID-19 cases. Without stringent control measures, including limited closure of educational institutions and a greatly accelerated vaccine rollout, COVID-19 hospitalizations and deaths across England in the first 6 months of 2021 were projected to exceed those in 2020. VOC 202012/01 has spread globally and exhibits a similar transmission increase (59 to 74%) in Denmark, Switzerland, and the United States.

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Mathematical Models for Assessing Vaccination Scenarios in Several Provinces in Indonesia

10.1101/2020.12.21.20248241 ◽

2020 ◽

Author(s):

N. Nuraini ◽

K. Khairudin ◽

P. Hadisoemarto ◽

H. Susanto ◽

A. Hasan ◽

...

Keyword(s):

Mathematical Models ◽

Age Groups ◽

Transmission Model ◽

West Java ◽

Dynamic Transmission Model ◽

Simulation Results ◽

Age Structured

AbstractTo mitigate more casualties from the COVID-19 outbreak, this study assessed optimal vaccination scenarios, considering some existing healthcare conditions and some assumptions, by developing SIQRD (Susceptible-Infected-Quarantine-Recovery-Death) models for Jakarta, West Java, and Banten, in Indonesia. The models included an age-structured dynamic transmission model that naturally could give different treatments among age groups of population. The simulation results show that the timing and period’s length of the vaccination should be well planned and prioritizing particular age groups will give significant impact on the total number of casualties.

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A High Performance Target Tracing Transmission Model Oriented to Lifecycle Maximization

Journal of Sensors ◽

10.1155/2016/5401923 ◽

2016 ◽

Vol 2016 ◽

pp. 1-11

Author(s):

Zhong-Nan Zhao ◽

Pei-Li Qiao ◽

Jian Wang

Keyword(s):

High Speed ◽

High Performance ◽

Network Performance ◽

Transmission Rate ◽

Relay Node ◽

High Rate ◽

Transmission Model ◽

Limited Resources ◽

Speed Sensor ◽

Rate Transmission

For the high speed sensor networks applications such as Internet of Things, multimedia transmission, the realization of high-rate transmission under limited resources has become a problem to be solved. A high speed transmission and energy optimization model oriented to lifecycle maximization is proposed in this paper. Based on information-directed mechanism, the energy threshold set and the relay node distance selection will be done in the process of target tracing, as a result, retaining a balance between transmission rate and energy consumption. Meanwhile, multiagent coevolution is adopted to achieve the maximum of network lifecycle. Comparing with the relevant methods, indexes for network such as hops, throughput, and number of active nodes, standard deviation of remaining energy, and the network lifecycle are considered, and the simulated experiments show that the proposed method will promote the transmission rate effectively, prolong the network lifecycle, and improve network performance as a whole.

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Multi-objective optimization of hydro-viscous flexible drive for dynamic characteristics using genetic algorithm

Industrial Lubrication and Tribology ◽

10.1108/ilt-12-2020-0472 ◽

2021 ◽

Vol ahead-of-print (ahead-of-print) ◽

Author(s):

Jianzhong Cui ◽

Hu Li ◽

Dong Zhang ◽

Yawen Xu ◽

Fangwei Xie

Keyword(s):

Genetic Algorithm ◽

Dynamic Characteristics ◽

Transmission Efficiency ◽

Outer Radius ◽

Transmission Model ◽

Design Parameters ◽

Multi Objective Optimization ◽

Content Type ◽

Multi Objective ◽

Dynamic Transmission Model

Purpose The purpose of this study is to investigate the flexible dynamic characteristics about hydro-viscous drive providing meaningful insights into the credible speed-regulating behavior during the soft-start. Design/methodology/approach A comprehensive dynamic transmission model is proposed to investigate the effects of key parameters on the dynamic characteristics. To achieve a trade-off between the transmission efficiency and time proportion of hydrodynamic and mixed lubrication, a multi-objective optimization of friction pair system by genetic algorithm is presented to obtain the optimal combination of design parameters. Findings Decreasing the engagement pressure or the ratio of inner and outer radius, increasing the lubricating oil viscosity or the outer radius will result in the increase of time proportion of hydrodynamic and mixed lubrication, as well as the transmission efficiency and its maximum value. After optimization, main dynamic parameters including the oil film thickness, angular velocity of the driven disk, viscous torque and total torque show remarkable flexible transmission characteristics. Originality/value Both the dynamic transmission model and multi-objective optimization model are established to analyze the effects of main design parameters on the dynamic characteristics of hydro-viscous flexible drive.

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Agent-based modelling study of antimicrobial-resistant Neisseria gonorrhoeae transmission in men who have sex with men: towards individualised diagnosis and treatment

Sexual Health ◽

10.1071/sh18235 ◽

2019 ◽

Vol 16 (5) ◽

pp. 514 ◽

Cited By ~ 2

Author(s):

Adam K. Zienkiewicz ◽

Nicolás Verschueren van Rees ◽

Martin Homer ◽

Jason J. Ong ◽

Hannah Christensen ◽

...

Keyword(s):

Index Case ◽

Point Of Care ◽

New Technology ◽

Drug Dose ◽

Transmission Model ◽

Contact Network ◽

Global Public Health ◽

Reference Case ◽

Dynamic Transmission Model ◽

Sex With Men

Background Antimicrobial-resistant (AMR) gonorrhoea is a global public health threat. Discriminatory point-of-care tests (POCT) to detect drug sensitivity are under development, enabling individualised resistance-guided therapy. Methods: An individual-based dynamic transmission model of gonorrhoea infection in MSM living in London has been developed, incorporating ciprofloxacin-sensitive and resistant strains. The time-dependent sexual contact network is captured by periodically restructuring active connections to reflect the transience of contacts. Different strategies to improve treatment selection were explored, including discriminatory POCT and selecting partner treatment based on either the index case or partner susceptibility. Outcomes included population prevalence of gonorrhoea and drug dose counts. Results: It is shown that using POCT to detect ciprofloxacin-sensitive infections could result in a large decrease in ceftriaxone doses (by 70% compared with the reference case in the simulations of this study). It also suggests that ceftriaxone use can be reduced with existing technologies, albeit to a lesser degree; either using index case sensitivity profiles to direct treatment of partners, or testing notified partners with strain discriminatory laboratory tests before treatment, reduced ceftriaxone use in our model (by 27% and 47% respectively). Conclusions: POCT to detect ciprofloxacin-sensitive gonorrhoea are likely to dramatically reduce reliance on ceftriaxone, but requires the implementation of new technology. In the meantime, the proportion of unnecessary ceftriaxone treatment by testing partners before treatment could be reduced significantly. Alternatively, index case sensitivity profiles could be used to select effective treatments for partners.

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