Experimental Techniques for Bearing Impedance Measurement

1991 ◽  
Vol 113 (3) ◽  
pp. 335-342 ◽  
Author(s):  
M. J. Goodwin
Keyword(s):  
Experimental Measurement ◽  
Computer Software ◽  
Impedance Measurement ◽  
Experimental Techniques ◽  
Design Stage ◽  
Theoretical Treatment ◽  
Yield Coefficient ◽  
Experimental Procedure ◽  
Advantages And Disadvantages ◽  
Theoretical Predictions

The dynamic characteristics of rotating machinery are almost always influenced by the impedances of the machine bearings (including the bearing supports) and it is particularly important to know of their likely values at the design stage when predicting machine critical speeds, unbalance response, and stability. In many instances the vital data may be obtained from theory which must be confirmed by experimental measurement beforehand, or alternatively the data may be obtained directly from experimental measurement when the appropriate bearing has already been manufactured. The experimental techniques available for use in the measurement of bearing impedances are varied, both in their experimental procedure and in the theoretical treatment of the data that is gathered. The aim of this paper is to provide a concise account of these techniques, and to discuss the potential advantages and disadvantages of each approach. In this document, the procedures described are classified in terms of the type of experimental measuring equipment required. These vary from the simplest of test rigs, which provide only a static load in one direction and where impedances can be evaluated by hand calculation, to sophisticated apparatus capable of providing static and dynamic loads in several directions and which require computer software to extract the bearing impedances from the measured data. The type of experimental procedure selected by the rotor dynamicist will depend upon the experimental facilities available, on the time available to carry out the testing, and on the required reliability of results. Each of these considerations is discussed for each procedure described. It is concluded that measurements made using multifrequency test signals provide more reliable data, although all measurement methods yield coefficient values which agree with theoretical predictions to within about 20 percent in general, and all methods have a significant scatter of results associated with their use.

Experimental Study of Propeller-Induced Vibratory Pressures on Simple Surfaces and Correlation With Theoretical Predictions

1964 ◽  
Vol 8 (05) ◽  
pp. 15-28
Author(s):  
J. P. Breslin ◽  
T. Kowalski
Keyword(s):  
Free Space ◽  
Three Dimensional ◽  
Theoretical Treatment ◽  
Plate Boundaries ◽  
Practical Application ◽  
Finite Area ◽  
Experimental Procedure ◽  
Theoretical Predictions ◽  
Pressure Changes ◽  
Good Agreement

Vibratory pressures exerted on cylindrical and flat-plate boundaries due to a model propeller were measured at three advance coefficients. A number of "free-space" measurements also were made. All measurements were made by driving a propeller past fixed pressure gages. This method yielded curves of pressure changes which are entirely free from background noise. The magnitudes of the free-space pressures were found to be larger than one half the corresponding magnitudes measured by gages mounted flush in a large plate at equal clearances from the propeller. By postulating that the finite area of the gage diaphragm produces a partial image of the propeller (and hence a larger pressure than that in free space) an experimental procedure was devised for correcting for this finite-area effect yielding results in good agreement with theory. A theoretical treatment of this effect of finite gage size is given in Appendix 2. The decay of maximum amplitudes of vibrating pressures is shown by means of three-dimensional plots. The pressures were found to become vanishingly small within approximately one propeller diameter fore and aft of the center of the propeller. The comparison with theoretically calculated pressures and forces gives very close agreement for free-space pressures and reasonable agreement for forces on a cylindrical surface. The agreement of both pressures and forces with theory is excellent for operation near the design advance ratio. A strong plea is made for further experiments with ship models in an effort to develop design criteria for practical application.

scholarly journals Rotor Loading Characteristics of a Full-Scale Tidal Turbine

Energies ◽  
2019 ◽  
Vol 12 (6) ◽  
pp. 1035 ◽  
Author(s):  
Magnus Harrold ◽  
Pablo Ouro
Keyword(s):  
Turbulent Flows ◽  
Mechanical Loading ◽  
Full Scale ◽  
Design Stage ◽  
Flow Profile ◽  
Expected Return ◽  
Tidal Turbines ◽  
Theoretical Predictions ◽  
Tidal Turbine

Tidal turbines are subject to highly dynamic mechanical loading through operation in some of the most energetic waters. If these loads cannot be accurately quantified at the design stage, turbine developers run the risk of a major failure, or must choose to conservatively over-engineer the device at additional cost. Both of these scenarios have consequences on the expected return from the project. Despite an extensive amount of research on the mechanical loading of model scale tidal turbines, very little is known from full-scale devices operating in real sea conditions. This paper addresses this by reporting on the rotor loads measured on a 400 kW tidal turbine. The results obtained during ebb tidal conditions were found to agree well with theoretical predictions of rotor loading, but the measurements during flood were lower than expected. This is believed to be due to a disturbance in the approaching flood flow created by the turbine frame geometry, and, to a lesser extent, the non-typical vertical flow profile during this tidal phase. These findings outline the necessity to quantify the characteristics of the turbulent flows at sea sites during the entire tidal cycle to ensure the long-term integrity of the deployed tidal turbines.

Recent Progress on Controlled Dielectrophoretic Assembly of Carbon Nanotubes

2012 ◽  
Vol 531-532 ◽  
pp. 485-489
Author(s):  
Chao Ding ◽  
Li Bao An ◽  
Xiao Xia Yang ◽  
Yan Yan Liu
Keyword(s):  
Carbon Nanotubes ◽  
Impedance Measurement ◽  
Research Progress ◽  
Mechanical And Thermal Properties ◽  
Single Electron Transistors ◽  
Advantages And Disadvantages ◽  
Field Emission Displays ◽  
Impedance Monitoring ◽  
Time Gap ◽  
Functional Components

Carbon nanotubes (CNTs) have drawn extensive research interest for a variety of applications in single electron transistors, field emission displays, interconnects, sensors, energy storage, composites, and many others due to their excellent electrical, mechanical, and thermal properties. One requirement for many of these applications is the need to integrate CNTs into various devices or circuits as functional components and different manipulation methods have been developed. This paper addresses the assembly of CNTs by dielectrophoresis (DEP) and reviews recent research progress of controlled assembly of CNTs. Totally six approaches are introduced in which different techniques including impedance measurement, optical induced DEP, floating electrode DEP, self-limiting resistor, fluidic assisted deposition, and real-time gap impedance monitoring of DEP are respectively used to control the yield of the DEP process. The advantages and disadvantages of these methods are analysed. The purpose is to help automating the DEP process of CNTs and other one-dimensional nanomaterials by presenting these advanced control techniques.

scholarly journals The Applications of Mathematics and Modular Art in the Education of Interior Design

2018 ◽  
Vol 13 (1) ◽  
pp. 36
Author(s):  
Mayyadah Fahmi Hussein
Keyword(s):  
Interior Design ◽  
Latin Square ◽  
Design Tool ◽  
Basic Design ◽  
Pattern Design ◽  
Experimental Procedure ◽  
Practical Applications ◽  
Advantages And Disadvantages ◽  
New Learning ◽  
The Subject

The new learning processes should be piloted therefore; Interior design schools should be updated according to the results of progress in teaching methods. For this reason, the objective of this study is to define the formulation of a mixed learning model for mathematics applications and technical models within the interior educational system. This paper’s main objective is to find explanations of incorporating the cotemporary interior design within the Mathematics & Modular art content, and to seek modern solutions featuring as new methods. This paper was carried out by experimental procedure in University of Petra/Department of Interior Design based on basic design courses in the academic years 2011-2012 where the researcher took a sample of ten student forms based on the models which were chosen in this experiment combining both difficulty & ease. The students have completed these ten shapes by altering mathematical approach (Latin square) to create a new pattern design. Art with Mathematical approaches have been applied in different practical applications as a basic design tool, and conclusions have been reached on the merits of the design. The advantages and disadvantages of teaching interior design have been introduced from Art & mathematical perspective as a method of design based on the results found during the practical applications of basic design projects and from information in publications on the subject. Relying on these proposed models, the proposals will constantly develop design tools. In conclusion, educating future designers to digest the essence of these approaches will make it possible to train professionals who correctly use and understand the developed technologies that can create futuristic designs.

The effect of dome properties on design of the axial symmetric cylindrical wall

2021 ◽  
Vol 7 (1) ◽  
pp. 11
Author(s):  
Aylin Ece Kayabekir
Keyword(s):  
Reinforced Concrete ◽  
Computer Program ◽  
Numerical Investigation ◽  
Computer Software ◽  
General Purpose ◽  
Design Stage ◽  
Cylindrical Wall ◽  
Support Condition ◽  
Structural Concrete ◽  
Analysis And Design

The usage of computer software in civil engineering has expanded in last decades. Many general-purpose and special-purpose commercial programs perform a very important function, especially at the design stage. In this study, a computer program is introduced for the analysis and design of the axial symmetric cylindrical wall considering the dome effects. Analysis processes are carried out according to Flexibility theory with long wall assumption and during the reinforced concrete (RC) design of the wall, ACI 318-Building code requirements for structural concrete are considered. In numerical investigation, the effects of the dome properties (thickness and height) on the analysis and design of the wall are investigated by performing a totally 72 case analyzes. These cases include different support condition at bottom of the wall, wall heights, dome thicknesses and heights. According to analysis results, it is concluded that effects of dome thickness and heights on the wall on the wall are very limited.

Tree-Building Algorithms and Philosophies

2021 ◽  
pp. 142-185
Author(s):  
Andrew V. Z. Brower ◽  
Randall T. Schuh
Keyword(s):  
Computer Software ◽  
Bayesian Techniques ◽  
Advantages And Disadvantages ◽  
Computational Capability ◽  
Intractable Problems ◽  
Character Weighting ◽  
Alternative Approaches ◽  
Tree Building ◽  
The Relationship ◽  
Parsimony Criterion

This chapter evaluates “quantitative cladistics” in detail, including the issues of fit, parsimony algorithms, and character weighting. Although systematists have long associated characters with taxa, the relationship between character data and “phylogeny” has not always been obvious. The ideas of Willi Hennig clarified this relationship, and the formalization of these concepts in a quantitative method, via the parsimony criterion, allowed for computer implementation of phylogenetic inference and the feasible solution of previously intractable problems. It is this computational capability that took the study of taxonomic relationships from an almost purely qualitative and speculative enterprise to one dominated by the use of computer software and “objective” methodologies. The chapter then discusses the use, advantages, and disadvantages of maximum likelihood and Bayesian techniques as alternative approaches to the application of parsimony.

Whole Life/Life Cycle Costing During the Design Stage of a Construction Project

2020 ◽  
Vol 9 (2) ◽  
pp. 66-87
Author(s):  
Daniel Clarke-Hagan ◽  
Michael Curran ◽  
John Spillane ◽  
Mary-Catherine Greene
Keyword(s):  
Life Cycle ◽  
Qualitative Methodology ◽  
Construction Project ◽  
Life Cycle Costing ◽  
Design Stage ◽  
Life Cycle Costs ◽  
Mind Mapping ◽  
Advantages And Disadvantages ◽  
Mapping Software ◽  
Whole Life Costing

The calculations of life cycle costs (LCC) and whole life costs (WLC) are important tools in the life cycle of a project. The aim of this research is to examine life cycle costing, whole life costing, and the possible advantages and disadvantages to their introduction and use. A qualitative methodology encompassing an in-depth literature review, interviews, and qualitative analysis using mind mapping software, this research is important as it can add to the industry's understanding of the design process. It highlights reasons for the success or failure of a construction project, in terms of sustainability at the design stage. Results indicate that the researched topics had many advantages but also had inherent disadvantages. It is found that the potential advantages outweighed disadvantages, but uptake within industry is still slow and that better promotion and their benefits to sustainability, the environment, society, and the industry are required.

Reduction of Impact Noise at the Design Stage: A Specific Case Study

1972 ◽  
Vol 186 (1) ◽  
pp. 391-399
Author(s):  
M. A. Salter ◽  
B. Downs ◽  
G. R. Wray
Keyword(s):  
Experimental Approach ◽  
Design Stage ◽  
Experimental Investigations ◽  
Theoretical Treatment ◽  
Impact Noise ◽  
Design Changes ◽  
Machine Cycle ◽  
Mechanism Of Impact ◽  
The Impact

A case study is made on the tack driving assembly of a boot and shoe lasting machine, and relates to the impact noise occurring during part of the machine cycle. Much of the noise is radiated due to vibrations at several frequencies of the tack driver lifting lever, which is excited by the direct application of impacts during the tack driving process. An experimental approach in applying noise reduction principles to various components of the assembly has been preferred to a more complex theoretical treatment, since the identification of the mechanism of impact noise generation and its subsequent abatement is directly relevant to most machine designers faced with the possibility of impact noise problems in other types of machinery. Small design changes, based on the knowledge gained from the experimental investigations, have resulted in noise reductions from 10 to 14 dB being achieved.

scholarly journals Study on Early Warning Method for Water Inrush in Tunnel Based on Fine Risk Evaluation and Hierarchical Advance Forecast

Geosciences ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 392 ◽  
Author(s):  
Sheng Wang ◽  
Shucai Li ◽  
Liping Li ◽  
Shaoshuai Shi ◽  
Zongqing Zhou ◽  
...  
Keyword(s):  
Early Warning ◽  
Risk Evaluation ◽  
Water Inrush ◽  
Entropy Method ◽  
Design Stage ◽  
Tunnel Construction ◽  
Evaluation Theory ◽  
Strongly Nonlinear ◽  
Advantages And Disadvantages ◽  
And Control

Water inrush is one of the most frequent and harmful geological disasters in tunnel construction. In order to effectively prevent and control the occurrence of water inrush, an early warning method based on fine risk evaluation and hierarchical advanced forecast is proposed. Water inrush is a complex dynamic coupling factors system, the relationship between influencing factors and water inrush is strongly nonlinear. Therefore, the efficacy coefficient model, which has the advantages of standardization, conciseness, and freedom from subjective factors, is improved nonlinearly. The fine risk evaluation theory and method based on the improved efficacy coefficient model consisted of two parts: one is static evaluation used in design stage, and the other is dynamic evaluation applied in the construction stage. The index weights are determined scientifically and reasonably by Analytical Hierarchy Process (AHP) and the entropy method. According to the fine risk evaluation results, combined with the advantages and disadvantages of various forecasting methods, a multistep hierarchical detection method of disaster resources for water inrush is proposed to identify the occurrence characteristics and failure level of disaster sources. The theory has been successfully applied to the #3 inclined well of Yuelongmen Tunnel in Cheng-Lan Railway. The evaluation results had good agreement with the actual excavation data, which indicates that the model is of high credibility and feasibility. The method could improve the prediction accuracy of water inrush and explore geometric characteristics and filling of disaster-causing structures. It is of great significance for avoiding water inrush and guiding the rapid and safe tunnel construction.

Experimental Cutting Tool Temperature Distributions

2003 ◽  
Vol 125 (4) ◽  
pp. 667-673 ◽  
Author(s):  
Mark R. Miller ◽  
George Mulholland ◽  
Charles Anderson
Keyword(s):  
Cutting Tool ◽  
Infrared Imaging ◽  
Production Costs ◽  
Experimental Techniques ◽  
Tool Temperature ◽  
Orthogonal Machining ◽  
Temperature Distributions ◽  
Theoretical Predictions ◽  
Experimental Cutting ◽  
Machining Operations

High temperatures in machining cutting zones activate wear mechanisms that decrease tool life and increase production costs and yet this phenomenon is not fully understood nor characterized. Although experimental work has been performed, the techniques used have generally been difficult to apply, and lacked sufficient resolution and or acceptable accuracy. Theoretical predictions and computational simulations have been performed to gain further insight into this problem but could not be accurately validated due to the lack of sufficient experimental temperature data. Experimental techniques using modern, digital infrared imaging were developed and successfully applied during this study to gather cutting tool temperature distributions from orthogonal machining operations. This new process has seemingly overcome many problems associated with past experimental techniques.

Sign in / Sign up

Export Citation Format

Share Document