scholarly journals The Effect of Unbalance Mass on the Necessary Conditions of the Double-Support Rotor Autobalancing Stability

2019 ◽  
pp. 71-82
Author(s):  
A.N. Gorbenko ◽  
S.Kh. Shmelev ◽  
G. Strautmanis
Keyword(s):  
Necessary Conditions ◽  
Dynamics Analysis ◽  
Mass Center ◽  
Quantitative Criterion ◽  
Spherical Type ◽  
Double Support ◽  
System Parameters ◽  
Spatial Oscillations ◽  
The Common ◽  
Rotor Type

The analysis of necessary conditions for autobalancing stability of rotor, which performs spatial oscillations, was carried out in this paper taking into account the influence of unbalance and autobalancer masses. It was found that the using of traditional models, where unbalance and autobalancer masses are assumed small, could lead to significant errors in the dynamics analysis of spatially moving rotor. The influence of this factor leads to the doubling of the critical rotational speeds spectrum. Moreover, the system motion between the split critical frequencies is unstable. There may be one or two onset areas of autobalancing mode motion depending on the dynamic rotor type, its location relative to the supports, the unbalance mass and other system parameters. It was found that rotors, that are long type or close to the spherical type, are the most sensitive to this factor. On the other hand, rotors of the short type are weakly sensitive. It is shown that the most preferred case is when the unbalance and autobalancer location plane passes through the common mass center of the composite rotor. The quantitative criterion is formulated for the necessity of taking into account (or not taking into account) the influence of this factor when analyzing the system dynamics

scholarly journals Computational performance analysis of an airborne rotor-type electricity generator wind turbine

2019 ◽  
Vol 128 ◽  
pp. 09007
Author(s):  
Doğan Günes ◽  
Ergin Kükrer ◽  
Tolga Aydoğdu
Keyword(s):  
Fluid Dynamics ◽  
Wind Turbine ◽  
Electrical Energy ◽  
Dynamics Analysis ◽  
Innovative Design ◽  
Computational Performance ◽  
Computational Fluid Dynamics Analysis ◽  
Turbine Design ◽  
Design Proposal ◽  
Rotor Type

This paper presents an analysis of the possible performance of a proposed airborne rotor type electricity generator wind turbine design. The innovative design proposal by inventor is based on the rotation of the airborne structure with blades attached to the airborne zeppelin and thus it is called an airborne rotor generator. In this paper computational fluid dynamics analysis of a model close to the proposed design is carried out and the results are presented. The proposed design examples are set to produce 10-100KW. The electrical energy generated through two symmetrically placed alternators at both ends of the zeppelin is transferred to the ground-based system through the tethered cords used to also stabilize the system. Thus, an airborne rotor generator is formed.

The Improvement of Refrigerators Rotary Oil Pump

2013 ◽  
Vol 365-366 ◽  
pp. 86-90
Author(s):  
Yan Jing ◽  
Feng Zhao
Keyword(s):  
Lubricating Oil ◽  
Working Environments ◽  
Oil Pump ◽  
The Common ◽  
Design Ideas ◽  
And Storage ◽  
Rotor Type

Screw refrigerators are widely used in subzero refrigeration and storage fields. The manufacturers always use rotor-type pumps as their lubricating oil pumps. This paper introduces the advantages of screw refrigerators, the usage of oil pumps and the working environments. It mainly studies the common faults of oil pump, proposes several design ideas for analysis and comparison and determines the final improvement schemes on the premise of comprehensively considering structure, performance and cost.

Penetration Rates and Stability of Motions of a Harmonically Forced Fore-Aft Vibrating Plow

1974 ◽  
Vol 96 (2) ◽  
pp. 653-658
Author(s):  
M. Senator
Keyword(s):  
Steady State ◽  
Skin Friction ◽  
Necessary Conditions ◽  
Integer Number ◽  
Harmonic Force ◽  
Optimum Performance ◽  
System Parameters ◽  
Tip Resistance

A fore-aft vibrating plow with applied harmonic and bias forces, and with soil-blade interaction modeled by a constant tip resistance in uncut soil and zero skin friction is studied analytically. Necessary conditions are found which must be satisfied by transition crank angles if steady state motions with velocity period equal to an integer number of harmonic force periods are to exist. The infinitesimal stability of these motions is examined and the range of parameters over which stable and unstable motions exist is delineated. Average plowing speeds corresponding to these regular motions are computed and the variation of plowing speed with system parameters is found. These results are useful, both for estimating penetration rates of conceptual plows and for adjusting machine parameters to obtain optimum performance.

BIFURCATIONS OF THE COMMON LEVEL SETS OF ATOMIC HYDROGEN IN VAN DER WAALS POTENTIAL

2003 ◽  
Vol 13 (01) ◽  
pp. 107-114 ◽  
Author(s):  
J. KHARBACH ◽  
S. DEKKAKI ◽  
A. T.-H. OUAZZANI ◽  
M. OUAZZANI-JAMIL
Keyword(s):  
Level Sets ◽  
Van Der Waals ◽  
Space Structure ◽  
Classical Dynamics ◽  
Anharmonic Oscillators ◽  
Numerical Investigations ◽  
System Parameters ◽  
Phase Space Structure ◽  
Liouville Tori ◽  
The Common

The classical dynamics of a hydrogen atom in a generalized van der Waals potential is investigated. In order to carry out the analytical and numerical investigations for a range of parametric values, we removed the singularity of the problem using Levi–Civita regularization and converted the problem into that of two coupled sextic anharmonic oscillators. We give a complete description of the real phase space structure of the converted system and give also an explicit periodic solution for singular common-level sets of the first integrals. All generic bifurcations of Liouville tori were determined theoretically. Numerical investigations are carried out for all generic bifurcations and we observe chaos-order-chaos transition when one of the system parameters is varied.

scholarly journals Detachable Pairs in 3-Connected Matroids

2021 ◽  
Author(s):  
◽  
Alan Williams
Keyword(s):  
Necessary Conditions ◽  
Single Element ◽  
Important Theorem ◽  
Connected Matroid ◽  
The Common ◽  
Splitter Theorem

<p>The classical tool at the matroid theorist’s disposal when dealing with the common problem of wanting to remove a single element from a 3-connected matroid without losing 3-connectivity is Tutte’s Wheels-and-Whirls Theorem. However, situations arise where one wishes to delete or contract a pair of elements from a 3-connected matroid whilst maintaining 3-connectedness. The goal of this research was to provide a new tool for making such arguments. Let M be a 3-connected matroid. A detachable pair in M is a pair x, y ∈ E(M) such that either M\x, y or M/x, y is 3-connected. Naturally, our aim was to find the necessary conditions on M which guarantee the existence of a detachable pair. Triangles and triads are an obvious barrier to overcome, and can be done so by allowing the use of a Δ − Y exchange. Apart from these matroids with three-element 3-separating sets, the only other class of matroids that fail to contain a detachable pair for which no bound can be placed on the size of the ground set is the class of spikes. In particular, we prove the following result. Let M be a 3-connected matroid with at least thirteen elements. If M is not a spike, then either M contains a detachable pair, or there exists a matroid M′ where M′ is obtained by performing a single Δ − Y exchange on either M or M* such that M′ contains a detachable pair. As well as being an important theorem in its own right, we anticipate that this result will be essential in future attempts to extend Seymour’s Splitter Theorem in a comparable manner; where the goal would be to obtain a detachable pair as well as maintaining a 3-connected minor. As such, much work has been done herein to study the precise configurations that arise in 3-separating subsets which themselves yield no detachable pair.</p>

scholarly journals A Short Note on the Common Fixed Points of the Geraghty Contraction of Type ES,T

2018 ◽  
Vol 51 (1) ◽  
pp. 233-240 ◽  
Author(s):  
Badr Alqahtani ◽  
Andreea Fulga ◽  
Erdal Karapınar
Keyword(s):  
Fixed Points ◽  
Existence And Uniqueness ◽  
Necessary Conditions ◽  
Short Note ◽  
Common Fixed Points ◽  
Coincidence Points ◽  
The Common ◽  
Contraction Type

Abstract In this paper, we propose a new contraction type for two self-mappings and investigate the necessary conditions for the existence and uniqueness of coincidence points and common fixed points, respectively. We put some examples to illustrate our main results.

Limit Cycles in a Family of Planar Piecewise Linear Differential Systems with a Nonregular Separation Line

2019 ◽  
Vol 29 (08) ◽  
pp. 1950109
Author(s):  
Song-Mei Huan ◽  
Xiao-Song Yang
Keyword(s):  
Limit Cycles ◽  
Necessary Conditions ◽  
Piecewise Linear ◽  
Differential Systems ◽  
System Parameters ◽  
Separation Line ◽  
Linear Differential Systems ◽  
Inflection Points ◽  
Sufficient And Necessary Conditions ◽  
Linear Differential

In this paper, we investigate the number of crossing limit cycles in a family of planar piecewise linear differential systems with two zones separated by a nonregular line formed by two rays starting at the origin. By studying the dynamics of each subsystem, a thorough study including the parameteric expressions and main properties of some section maps is performed. Especially, different to the case with a straight separation line, it is proved that each section map can be piecewise with two different pieces and can have at most one inflection point. In addition to this, for the existence of these inflection points, some sufficient and necessary conditions satisfied by the system parameters are obtained. Based on these results, the importance played by these inflection points in increasing the maximum number of limit cycles in such systems is verified by providing a concrete example having five nested limit cycles with two crossing one separation ray and the other three crossing both separation rays. So, the five limit cycles obtained here are different from that obtained in the existing literature, where all the limit cycles cross both separation rays.

scholarly journals Philosophical aspect of installment trading in Islamic Rules

2021 ◽  
Vol 9 (SPE2) ◽  
Author(s):  
Sarsembayev Assylbek ◽  
Anarbayev Nurlan ◽  
Kundakova Laura ◽  
Karatyshkanova Kymbat ◽  
Myrzabekov Muratbek
Keyword(s):  
Necessary Conditions ◽  
Industrial Enterprises ◽  
The World ◽  
Philosophical Aspect ◽  
The Common ◽  
Trade Deals

In this article, I would like to stop at one of the common types of trade called “Installment trading”, which is permitted in Islam, if the necessary conditions required in the Shari'ah will be fulfilled. At the same time, installment trading in Islam (Installment sale) is only one of many types of sale and purchase. Now this type of trade is very common in the world. Individuals and various industrial enterprises, firms, etc. use installment trading. Instalment selling is often used in Islamic financing. One of the types of installment trading is As-Salam, when payment for goods is made long before it was purchased, and which is known according to Arab sources long before Islam arose, used in Islam more than a thousand years ago. It should be noted that trade in Islam is permitted and this is because all the messengers of Allah were sent to change what God prohibited, but with regard to trade, there was no prohibition. In particular, the proof of that is the trade deals of the Messenger of Allah (peace be upon him).

The Dynamics of Labor Militancy in the Extractive Sector: Kazakhstan’s Oilfields and South Africa’s Platinum Mines in Comparative Perspective

2019 ◽  
Vol 53 (6) ◽  
pp. 992-1024
Author(s):  
Allison D. Evans ◽  
Rudra Sil
Keyword(s):  
Labor Relations ◽  
Necessary Conditions ◽  
Extractive Industries ◽  
Business Elites ◽  
Labor Militancy ◽  
Security Personnel ◽  
Platinum Belt ◽  
Globalized Economy ◽  
The Common ◽  
Extractive Sector

This article investigates why, in two very different regimes, similarly high levels of labor militancy are evident in Kazakhstan’s oilfields and South Africa’s platinum belt. It also explores the common dynamics leading up to the massacres at Zhanaozen (2011) and Marikana (2012). The hypothesis-generating most different systems comparison highlights the challenges of labor relations where extraction at fixed sites combines with volatile prices and shareholder pressures in a globalized economy to raise the stakes for business, labor, and state. Also significant are blockages in existing channels for bargaining linked to quiescent unions. These jointly necessary conditions account for increased militancy in extractive industries in Kazakhstan and South Africa. To account for the Zhanaozen and Marikana massacres, timing and sequence are considered. Both standoffs came later in the strike wave, prompting impatient state and business elites to criticize the protests as “criminal” acts, and priming security personnel to employ violent repression.

Hidden Attractors and Dynamical Behaviors in an Extended Rikitake System

2015 ◽  
Vol 25 (02) ◽  
pp. 1550028 ◽  
Author(s):  
Zhouchao Wei ◽  
Wei Zhang ◽  
Zhen Wang ◽  
Minghui Yao
Keyword(s):  
Hopf Bifurcation ◽  
Initial Conditions ◽  
Dynamics Analysis ◽  
Hidden Attractor ◽  
Hidden Attractors ◽  
System Parameters ◽  
Dynamical Behaviors ◽  
Rikitake System ◽  
Wide Range ◽  
Stable Equilibria

In this paper, an extended Rikitake system is studied. Several issues, such as Hopf bifurcation, coexistence of stable equilibria and hidden attractor, and dynamics analysis at infinity are investigated either analytically or numerically. Especially, by a simple linear transformation, the wide range of hidden attractors is noticed, and the Lyapunov exponents diagram is given. The obtained results show that the unstable periodic solution generated by Hopf bifurcation leads to the hidden attractor. The existence of hidden attractors that may render the system's behavior unpredictable not only depends on the value of system parameters but also on the value of initial conditions. The phenomena are important and potentially problematic in engineering applications.

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