scholarly journals Nonlinear Coupled Torsion/Lateral Vibration and Sommerfeld Behavior in a Double U-Joint Driveshaft

2020 ◽  
Vol 143 (3) ◽  
Author(s):  
Wei Yao ◽  
Hans DeSmidt
Keyword(s):  
Nonlinear Phenomenon ◽  
Shaft Speed ◽  
Rotor Speed ◽  
Load Torque ◽  
Angular Misalignment ◽  
Motor Torque ◽  
Rotor Systems ◽  
Rotor Imbalance ◽  
Pass Through ◽  
First Time

Abstract Many driveline systems are designed to accommodate angular misalignment by the use of flexible couplings or Universal Joints (U-Joints) which link individual shaft segments. The Sommerfeld effect is a nonlinear phenomenon observed in some rotor systems being driven through a critical speed when there is not enough power to accelerate the rotor through resonance. Previous studies have shown that rotor speed can become captured when transitioning through natural frequencies due to nonlinear interactions between a non-ideal driving input and rotor imbalance. This paper, for the first time, shows that this type of rotor speed capture phenomena can also be induced by driveline misalignment. During rotor spinup under constant motor torque, it is found that misalignment-induced rotor speed capture phenomena can occur as the shaft speed approaches ½ the first elastic torsional natural frequency. Depending on misalignment level and motor torque, the shaft speed will either dwell near this speed and then pass through, or the speed will become trapped. Here, a nonlinear rotordynamics model of a segmented driveshaft connected by two U-joints including effects of angular misalignment and load torque is developed for the study. This analysis also determines the minimum driveline misalignment angle for which the shaft speed capture phenomena will occur for a given motor torque and load torque condition.

Misalignment in Combi-Bearing: A Cause of Parametric Instability in Vertical Rotor Systems

2013 ◽  
Vol 135 (3) ◽  
Author(s):  
Jean-Claude Luneno ◽  
Jan-Olov Aidanpää ◽  
Rolf Gustavsson
Keyword(s):  
Journal Bearing ◽  
Contact Point ◽  
Parametric Instability ◽  
Rotor Speed ◽  
Angular Misalignment ◽  
Rotor Systems ◽  
Asymmetric Structures ◽  
Rotating Systems ◽  
Vertical Rotor ◽  
Stationary Frame

The dynamic characteristics of the combi-bearing (combined thrust-journal bearing) in vertical rotor systems were analytically modeled and experimentally verified in the authors’ previous publications. An angular misalignment, which may be caused by a possible manufacturing or assembling error, is introduced in the combi-bearing’s rotating collar. A new model of the defective combi-bearing has been derived. The derived model shows that the angular misalignment in the combi-bearing’s rotating collar generates an asymmetry in the rotor system at the combi-bearing’s location. The rotor system’s stiffness in its two translational X and Y directions differ at the combi-bearing’s location. Constant parameters and/or coefficients in rotating asymmetric structures appear to change with time when observed in the stationary frame. These time dependent parameters (coefficients) are the source of the so-called parametric instability in rotating systems. If the collar angular misalignment is located in the X-Z plane all rotor motions in this plane at the contact point between the combi-bearing and the rotor will be coupled. A parametric instability is observed within certain ranges of the rotor speed, depending on the magnitude of the angular misalignment.

scholarly journals Rigid ventilating video bronchoscope with forceps for bronchoscopic foreign body removal in children

2019 ◽  
Vol 5 (4) ◽  
pp. 1129
Author(s):  
Sagar Jawale ◽  
Parthapratim Gupta ◽  
Bharti Kulkarni
Keyword(s):  
Foreign Body ◽  
Gold Standard ◽  
Medical Literature ◽  
Rigid Bronchoscopy ◽  
Foreign Body Aspiration ◽  
Indian Children ◽  
Foreign Body Removal ◽  
Rigid Tube ◽  
Pass Through ◽  
First Time

<p>Bronchoscopic foreign body removal is a potentially dangerous and challenging procedure in pediatric surgery. bronchoscopy under general anaesthesia is the gold standard of diagnosis and management of foreign body aspiration. A large ventilating channel and better control over the tip of the instrument and cheaper instrument are the merits of rigid bronchoscopy over flexible one. Traditionally a rigid tube alone is used for this purpose which has extreme limitations of vision and it is risky. Foreign body aspiration typically occurs in 6 to 18 month age and the size of glottis is very small at this age. In Indian children who are small and malnourished the large assembly of sheath and telescope mounted forceps does not pass through the glottis. To overcome the limitations of the traditional equipment I designed my own bronchoscopy equipment by my 15 year of experience in bronchoscopy. This type of device is reported for the first time in medical literature and patent is filed for it at Mumbai office.</p><p> </p>

Influence of Compressor Deterioration on Engine Dynamic Behavior and Transient Stall-Margin

1999 ◽  
Author(s):  
Z. S. Spakovszky ◽  
J. B. Gertz ◽  
O. P. Sharma ◽  
J. D. Paduano ◽  
A. H. Epstein ◽  
...  
Keyword(s):  
Analytical Investigation ◽  
Tip Clearance ◽  
Shaft Speed ◽  
Rotor Speed ◽  
Commercial Aircraft ◽  
Stall Inception ◽  
Stall Margin ◽  
Engine Dynamic ◽  
System Mode ◽  
Flow Blockage

This paper presents an experimental and analytical investigation of compressor stability assessment during engine transient operation. A 2-dimensional, linear, compressible, state-space analysis of stall-inception (Feulner et al. (1996)) was modified to account for engine transients and deterioration, with the latter modeled as increased tip-clearance and flow blockage. Experiments were performed on large commercial aircraft engines in both undeteriorated and deteriorated states. Unsteady measurements of pressure in these test engines during rapid accelerations revealed the growth of pre-stall disturbances, which rotate at rotor speed and at approximately half rotor speed. These disturbances are stronger in deteriorated engines. The model showed that the signal at shaft speed was the first compressible system mode, whose frequency is near shaft speed, excited by geometric nonuniformities. The computed behavior of this mode during throttle transients closely matched engine data. The signal increased in strength as stall was approached and as the engine deteriorated. This work firmly establishes the connection between observed signals in the these engines and first principles stability models.

scholarly journals Invasive Pest and Disease Pathogen as Sneakers in Railways for Their Spread in Different Ecological Region: A New Report

2021 ◽  
Vol 3 (1) ◽  
pp. 124-127
Author(s):  
Suresh Borkar
Keyword(s):  
Insect Pest ◽  
Uttar Pradesh ◽  
Early Morning ◽  
Invasive Pest ◽  
Positive Phototaxis ◽  
Crop Pest ◽  
Ecological Region ◽  
Pass Through ◽  
Banana Leaves ◽  
First Time

A new pathway of travels by invasive pest and disease pathogen through railways, as sneakers, were noticed for the first time. The Indian railways passing through the soybean fields infested with Spodoptera litura, after evening attracted the moth of Spodoptera by the illuminating lights in the railways compartment and the moth enters into the compartment through open compartment windows. These moths remain in the railway compartment until the dawn and get out of the compartment as the early morning sun light enters into the compartments and are thus the sneakers crop pest in railways due to their unnoticed travels/transport. Such sneakers crop pest travels up to a distance of 600 km during the period of night from one ecological region to another ecological region having the same crop to infest or the alternative host crop of the pest to cause the fresh infestation. This phenomenon of pest travel was observed in the region of Lalitpur in Uttar Pradesh, India, having soybean infestation. This is a quick travel by the pest into different areas, unseen and unreported earlier and may occur in any part of the world where the railways pass through the infested crop areas and attract the positive phototaxis pest and transport them, as sneakers, in to another ecological region. In another instance, the Sigatoka disease pathogen of banana was also noticed to travels from one ecological region to another ecological region through the railways, as sneakers without notice. This phenomenon of disease pathogen’s travels was noticed in Jalgaon region from where the banana produce is transported to different parts of India. In the trading and transport of banana through railways, the loaders use the banana leaves infected with the sigatoka pathogen as a packaging material for banana bunches while loading the banana produce in the railway wagons for their transportation. Thus, the sigatoka pathogen travels up to a distance of 1200 km/day along with the banana produce through the railways. The sigatoka infected leaves, with the unloading of banana produce also sneaks into the new ecological region and spread to infect the banana crop available in the region. Thus, the positive phototaxis insect pest are the sneakers in the railways for their travels while diseases pathogens with healthy crop produce travels and embarks to sneaks into a new ecological region and thus the railways transport system unintentionally transport the crop pest and disease pathogen from one ecological region to another. The knowledge of this new travel pathway will be useful in finalizing the strategies of plant quarantine and management of invasive pest and disease pathogens.

scholarly journals Statement Kebijaksanaan Moneter

2012 ◽  
Vol 7 (1) ◽  
Author(s):  
Teguh Sihono
Keyword(s):  
Monetary Policy ◽  
Central Government ◽  
Positive Impact ◽  
Trade Agreement ◽  
Regional Government ◽  
Exchange Value ◽  
Policy Transmission ◽  
Pass Through ◽  
The Cost ◽  
First Time

Monetary policy at 2010 year like as statement and implemented by Indonesia Bank (BI), as a purpose to reach national economy development target. That is counted unemployment, inflation pressure, and suppress international balance payment deficit.  The monetary policy influence the first time tasted by banking monetary sector and then tasted by real sector.The monetary policy transmission can influence economy activity pass through some strip that is: the cost of capital, wealth channel, portofolio theory, and monetary theory. The latest purpose of monetary policy is watch over and take care of stability of rupiah value the thing which reflected at low level and inflation stability. Mechanism of monetary policy  the thing which implementation with rate BI policy for influence inflation pass through some strip among others; rate of interest, credit, exchange value, asset and expectation.Application Asean-China Free Trade Agreement (AC-FTA) expected has an positive impact, concerning domestic economy, inflation level indicate a little increase in early 2010 year, although still appropriate revolves around target Indonesia Bank (BI) as high as ± 5% in January month 2010 noted down 0,84% (mtm) or 3,72%, formerly 0,33% (mtm) or 2,78%.   Domestic financial sector  became better by watched over money market inter bank (PUAB) even lean to decrees. To optimal result of monetary policy it is always together with fiscal policy and coordinate inter Indonesia Bank (BI) with central government along with regional government

scholarly journals On Early Evolution of Accreting Stars

1987 ◽  
Vol 115 ◽  
pp. 440-441
Author(s):  
B. M. Shustov ◽  
A. V. Tutukov
Keyword(s):  
Accretion Rate ◽  
Life Time ◽  
Early Evolution ◽  
Dominant Factor ◽  
Spherically Symmetric ◽  
Core Mass ◽  
The Core ◽  
Pass Through ◽  
The Moment ◽  
First Time

Accretion is a dominant factor in the early evolution of stars. The first time an accretion regime settles in is when a dusty opaque core forms. The mass of adiabatically contracting core inside the isothermally collapsing envelope depends only on the optical properties of dust. Spherically symmetric models of dusty cores were constructed using the Henyey technique with accretion boundary conditions (Menshchikov 1986). It appears that all protostars with normal chemical composition should pass through the stage of a quasistatic dusty core. The evolution of dusty cores is similar to that of “normal” young stars with accretion. One could distinguish convective, radiative and central core contraction phases. The life-time tc of the core depends on the core mass Mc and the accretion rate Ṁ (for Mc = 0.01 M⊙ and Ṁ = 1.6x10−6, 1.6x10−5 M⊙/year tc = 1.2x104, 3x103 yrs consequently). After dust exhaustion in the core it collapses and a central ionized quasistatic region grows in several tens of years. A flash of infrared radiation at the moment is not excluded.

This Is My Tribe

2020 ◽  
pp. 114-119
Author(s):  
Thomas Bancroft
Keyword(s):  
High School ◽  
Boreal Forests ◽  
Lake Erie ◽  
Puget Sound ◽  
High Elevation ◽  
Breeding Sites ◽  
The Third ◽  
Pass Through ◽  
Presque Isle ◽  
First Time

This chapter reflects on the author's first time seeing a ruby-crowned kinglet in the spring of sophomore year in high school. The author had gone to Presque Isle on Lake Erie to look for spring migrants with some birding buddies. Often during the third week of May, thousands of northbound birds congregate on this thin peninsula before making the overwater flight across the lake. Many of these species only pass through Pennsylvania from their Latin America winter homes to Canada's boreal forests where they breed. In Washington, wintering kinglets migrate down from high-elevation spruce-fir forests where they breed or from Canadian breeding sites, to live through the cold months in the Puget Sound lowlands.

Direct Hydraulic Permeability Measurements of Agarose Hydrogels Used as Cell Scaffolds

1999 ◽  
Author(s):  
Michael A. Soltz ◽  
Anna Stankiewicz ◽  
Gerard Ateshian ◽  
Robert L. Mauck ◽  
Clark T. Hung
Keyword(s):  
Fluid Flow ◽  
Articular Cartilage ◽  
Interstitial Fluid ◽  
Convective Transport ◽  
Hydraulic Permeability ◽  
Interstitial Fluid Flow ◽  
Pass Through ◽  
Fluid Pressurization ◽  
First Time

Abstract The objective of this study was to determine the intrinsic hydraulic permeability of 2% agarose hydrogels. Two-percent agarose was chosen because it is a concentration typically used for encapsulation of chondrocytes in suspension cultures [3–5], Hydraulic permeability is a measure of the relative ease by which fluid can pass through a material. Importantly, it governs the level of interstitial fluid flow as well as the interstitial fluid pressurization that is generated in a material during loading. Fluid pressurization is the source of the unique load-bearing and lubrication properties of articular cartilage [1,17] and represents a major component of the in vivo chondrocyte environment. We have previously reported that 2% agarose hydrogels can support fluid pressurization, albeit to a significantly lesser degree than articular cartilage [18]. Interstitial fluid flow gives rise to convective transport of nutrients and ions [6,7] and matrix compaction [9] which may serve as important stimuli to chondrocytes. We report for the first time the strain-dependent hydraulic permeability of 2% agarose hydrogels.

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