A New Method Seeking Optimal Parameters and Locations for Bearings of Rotating Machinery Systems

2003 ◽  
Author(s):  
Zhichu Fang ◽  
Miao Wang
Keyword(s):  
Objective Function ◽  
Rotating Machinery ◽  
The Other ◽  
New Method ◽  
System Stability ◽  
Control Technique ◽  
Modal Control ◽  
Optimal Parameters ◽  
Control Forces ◽  
Modal Space

A new method to optimize oil-film bearing parameters and choose the best bearing locations was presented here for rotor-bearing systems. Through applying the independent modal space control technique, optimized modal control forces and bearing forces guaranteeing system stability were deduced. The objective function minimizing the square difference between real bearing forces and optimized bearing forces was employed to optimize the bearing parameters. And then the other objective function was established to seek the best bearing locations among several possible choices. An interesting numerical example proved that the proposed approach is correct and efficient.

scholarly journals Intramax and other objective functions: The case of Slovenia

2016 ◽  
Vol 24 (2) ◽  
pp. 12-25 ◽  
Author(s):  
Samo Drobne ◽  
Mitja Lakner
Keyword(s):  
Objective Function ◽  
The Other ◽  
Objective Functions ◽  
Interaction Index ◽  
Functional Regions ◽  
Hierarchical Aggregation ◽  
Administrative Units

Abstract The use of different objective functions in hierarchical aggregation procedures is examined in this paper. Specifically, we analyse the use of the original Intramax objective function, the sum-of-flows objective function, the sum-of-proportions-to-intra-regional-flows objective function, Smart’s weighted interaction index, the first and second CURDS weighted interaction indices, and Tolbert and Killian’s interaction index. The results of the functional regionalisation have been evaluated by self-containment statistics, and they show that the use of the original Intramax procedure tends to delineate operationally the most persuasive and balanced regions that, regarding the intra-regional flows, homogeneously cover the analysed territory. The other objective functions give statistically better but operationally less suitable results. Functional regions modelled using the original Intramax procedure were compared to the regions at NUTS 2 and NUTS 3 levels, as well as to administrative units in Slovenia. We conclude that there are some promising directions for further research on functional regionalisation using hierarchical aggregation procedures.

scholarly journals On Newcomb's method of investigating periodicities and its application to Brückner's weather cycle

1914 ◽  
Vol 90 (619) ◽  
pp. 349-355
Keyword(s):  
Thermal Radiation ◽  
The Other ◽  
New Method ◽  
Critical Examination ◽  
Numerical Work ◽  
Average Value ◽  
Other Hand ◽  
Relationship Of ◽  
The Relationship ◽  
Great Simplicity

During the last few years of his life Prof. Simon Newcomb was keenly interested in the problem of periodicities, and devised a new method for their investigation. This method is explained, and to some extent applied, in a paper entitled "A Search for Fluctuations in the Sun's Thermal Radiation through their Influence on Terrestrial Temperature." The importance of the question justifies a critical examination of the relationship of the older methods to that of Newcomb, and though I do not agree with his contention that his process gives us more than can be obtained from Fourier's analysis, it has the advantage of great simplicity in its numerical work, and should prove useful in a certain, though I am afraid, very limited field. Let f ( t ) represent a function of a variable which we may take to be the time, and let the average value of the function be zero. Newcomb examines the sum of the series f ( t 1 ) f ( t 1 + τ) + f ( t 2 ) f ( t 2 + τ) + f ( t 3 ) f ( t 3 + τ) + ..., where t 1 , t 2 , etc., are definite values of the variable which are taken to lie at equal distances from each other. If the function be periodic so as to repeat itself after an interval τ, the products are all squares and each term is positive. If, on the other hand, the periodic time be 2τ, each product will be negative and the sum itself therefore negative. It is easy to see that if τ be varied continuously the sum of the series passes through maxima and minima, and the maxima will indicated the periodic time, or any of its multiples.

Locomotory Diseases Influence on Body Equilibrium and Balance

2014 ◽  
Vol 555 ◽  
pp. 652-658 ◽  
Author(s):  
Barbu Cristian Braun ◽  
Ileana Constanta Rosca
Keyword(s):  
Body Mass ◽  
Human Subjects ◽  
Force Plate ◽  
The Body ◽  
The Other ◽  
New Method ◽  
First Person ◽  
Mass Center ◽  
Stability Problems ◽  
Research Stage

The paper describes a new method of body equilibrium evaluation applied for different human subjects, the principal aim being to demonstrate to what extent any locomotory diseases could influence the body stability and equilibrium. The research refers to identify some persons with different locomotory diseases and to find both the influence on equilibrium and stability and if possible to improve them. Our research stage, synthesized in this paper, explains the body equilibrium evaluation in orthostatic posture done for different subjects, aged between 20 and 40 years. A number of 10 relevant persons were considered to be evaluated, 2 of them having some locomotory diseases. The first person presents any neuro-motor stability problems in case of long standing case. The other person has both Achilles tendons torn and operated. All subjects were tested in orthostatic posture, in 3 distinct positions, using a Kistler force plate. The experiments referred to the body mass center (COM) displacement in sagittal and lateral planes, representing an interesting characteristic for its equilibrium. It was shown that the person with diseases affecting stability presented a loss of equilibrium when standing for 10-20 seconds, i.e. higher COM displacements in both planes reported to the other tested subjects.

A Penalty-Free Method with Trust Region for Nonlinear Semidefinite Programming

2015 ◽  
Vol 32 (01) ◽  
pp. 1540006 ◽  
Author(s):  
Zhongwen Chen ◽  
Shicai Miao
Keyword(s):  
Semidefinite Programming ◽  
Objective Function ◽  
Penalty Function ◽  
Trust Region ◽  
Numerical Results ◽  
New Method ◽  
Penalty Parameter ◽  
Nonlinear Semidefinite Programming ◽  
Globally Convergent ◽  
Nonlinear Objective Function

In this paper, we propose a class of new penalty-free method, which does not use any penalty function or a filter, to solve nonlinear semidefinite programming (NSDP). So the choice of the penalty parameter and the storage of filter set are avoided. The new method adopts trust region framework to compute a trial step. The trial step is then either accepted or rejected based on the some acceptable criteria which depends on reductions attained in the nonlinear objective function and in the measure of constraint infeasibility. Under the suitable assumptions, we prove that the algorithm is well defined and globally convergent. Finally, the preliminary numerical results are reported.

A modified Runge-Kutta method

SIMULATION ◽  
1968 ◽  
Vol 10 (5) ◽  
pp. 221-223 ◽  
Author(s):  
A.S. Chai
Keyword(s):  
Error Estimate ◽  
Linear Combination ◽  
Experimental Results ◽  
The Other ◽  
New Method ◽  
Kutta Method ◽  
Starting Values ◽  
Runge Kutta Method ◽  
Runge Kutta ◽  
A Minor

It is possible to replace k2 in a 4th-order Runge-Kutta for mula (also Nth-order 3 ≤ N ≤ 5) by a linear combination of k1 and the ki's in the last step, using the same procedure for computing the other ki's and y as in the standard R-K method. The advantages of the new method are: It re quires one less derivative evaluation, provides an error estimate at each step, gives more accurate results, and needs a minor change to switch to the RK to obtain the starting values. Experimental results are shown in verification of the for mula.

Vibration Control Using Combined Independent Modal Space Control and Fuzzy Logic

1995 ◽  
Author(s):  
Mehran Asdigha ◽  
Robert Greif
Keyword(s):  
Physical Space ◽  
Fuzzy Rule ◽  
Fuzzy Reasoning ◽  
Performance Criterion ◽  
Active Damping ◽  
Rule Base ◽  
Control Law ◽  
Traditional Algorithm ◽  
Control Forces ◽  
Modal Space

Abstract Independent Modal Space Control (IMSC) is an established technique in active suppression of vibrations, in which the control law is developed exclusively in the modal space, allowing for independent design of the modal control forces. These forces can be transformed to the physical domain through modal transformation. The resulting controller is fixed-gain, with the active damping introduced to the system determined independently for each mode and is a function of the velocity for the under-damped case. In this work we propose to modify IMSC using fuzzy reasoning. The result is a new non-linear control law, embedding fuzzy reasoning and an implicit fuzzy rule-base that transforms the traditional algorithm from a fixed-gain to a variable-gain controller. The algorithm uses information about the displacement profile across the sensed locations to distribute the active damping rationally among the modal controllers. This new algorithm complements the “local” view of the traditional algorithm in the modal space, with a “global” view of the displacements in the physical space. The results show significant improvement in the settling time as the performance criterion.

Reduction of Forced Vibration Response by Optimum Balance of Linkage and Optimum Design of System

1997 ◽  
Author(s):  
She-min Zhang ◽  
Nobuyoshi Morita ◽  
Takao Torii
Keyword(s):  
Objective Function ◽  
Root Mean Square ◽  
Forced Vibration ◽  
Vibration Response ◽  
New Method ◽  
Mean Square ◽  
Design Variables ◽  
Calculation Results ◽  
Angular Velocities ◽  
Optimum Balance

Abstract This paper proposes a new method to reduce the forced vibration response of frame of linkage. It is that the root-mean-square (RMS) value of binary maximum (Bmax) of forced vibration response at a series of angular velocities is taken as the objective function, and the counterweight mass parameters of links and the stiffness factors are used as design variables. Then, it is found out that the responses are related not only to the Bmax value of shaking forces, but also to the shape of curve of shaking forces. The calculation results are compared with those of two other methods used in the reduction of forced vibration response by optimized balance of linkages, and it is shown that the new method can significantly reduce the responses of frame of linkage.

A simulation study of nonideal mixing effect on the dynamic response of an exothermic CSTR with Cholette’s model

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Chane-Yuan Yang ◽  
Yu-Shu Chien ◽  
Jun-Hong Chou
Keyword(s):  
Transfer Function ◽  
Dynamic Response ◽  
The Other ◽  
System Stability ◽  
Mixing Effect ◽  
Characteristic Roots ◽  
Mixing Parameter ◽  
Perfect Mixing ◽  
And Control ◽  
Inverse Response

Abstract The study of nonideal mixing effect on the dynamic behaviors of CSTRs has very rarely been published in the literature. In this work, Cholette’s model is employed to explore the nonideal mixing effect on the dynamic response of a nonisothermal CSTR. The analysis shows that the mixing parameter n (the fraction of the feed entering the zone of perfect mixing) and m (the fraction of the total volume of the reactor), indeed affect the characteristic roots of transfer function of a real CSTR, which determine the system stability. On the other hand, the inverse response and overshoot response are also affected by the nonideal mixing in a nonisothemal CSTR. These results are of much help for the design and control of a real CSTR.

XXVI.—A New Method of determining the Degree of Twist in Single Threads

1907 ◽  
Vol 27 ◽  
pp. 264-268 ◽  
Author(s):  
Thomas Oliver
Keyword(s):  
Opposite Direction ◽  
The Other ◽  
New Method

The determination of the degree of twist in a folded or ply thread composed of two or more strands is an easy matter. It is merely necessary to stretch the thread between two clamps, one being fixed and the other forming the end of a bar which can be rotated about its axis. A counter is attached to indicate the number of rotations. Rotating the thread in the opposite direction to its twist ultimately brings the singles parallel to each other. This point is easily observed. If we apply this method to single yarns we are at once confronted with the difficulty that the fibres constituting the yarn cannot be reduced to exact parallelism with each other.

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