A Sensitivity Analysis of Squeeze-Film Bearings

1982 ◽  
Vol 104 (4) ◽  
pp. 516-522 ◽  
Author(s):  
C. R. Burrows ◽  
O. S. Turkay
Keyword(s):  
Sensitivity Analysis ◽  
Amplitude Spectrum ◽  
Squeeze Film ◽  
Valuable Insight ◽  
Model Structure ◽  
Oil Film ◽  
Phase Spectra ◽  
Insight Into

It is shown that amplitude and phase spectra should not be used to assess the quality of estimates of oil-film coefficients unless the results are interpreted in conjunction with a sensitivity analysis of the bearing model. The implications of using only the amplitude spectrum are discussed. Sensitivity analysis is shown to give valuable insight into the problem of selecting test signals for estimating oil-film coefficients. Moreover the analysis gives an indication of the validity of the model structure.

Modeling of Oil-Film Forces in Squeeze-Film Bearings

1986 ◽  
Vol 108 (2) ◽  
pp. 262-269 ◽  
Author(s):  
C. R. Burrows ◽  
M. N. Sahinkaya ◽  
N. C. Kucuk
Keyword(s):  
Parameter Estimation ◽  
System Performance ◽  
Critical Speed ◽  
Nonlinear Models ◽  
Squeeze Film ◽  
Model Structure ◽  
Oil Film ◽  
Model Oil ◽  
Stiffness And Damping ◽  
Parameter Estimation Techniques

The role played by bearings in determining the dynamic characteristics of rotor-bearing systems is well known. This has led to various attempts to model oil-film force coefficients in terms of linearized stiffness and damping elements. The inadequacy of these theoretical coefficients to predict performance under certain conditions has led some authors to propose the use of nonlinear models. An alternative philosophy, developed in this paper, is to retain a linear model structure and seek to determine optimized coefficient values using modern parameter estimation techniques. It is shown that these estimated linearized parameters predict system performance more accurately than the theoretical linear coefficients; particularly when the rotor is operating near a critical speed.

Crowdsourcing Measures of Design Quality

2014 ◽  
Author(s):  
Hao Wu ◽  
Jonathan Corney ◽  
Michael Grant
Keyword(s):  
Design Research ◽  
Valuable Insight ◽  
Layout Problem ◽  
Generative Design ◽  
Design Quality ◽  
Design Task ◽  
Innovative Products ◽  
The Relationship ◽  
Insight Into

Today there are numerous examples of collaborative online communities effectively creating innovative products (e.g., RepRap, Linux). But the potential of anonymous crowds to also engage in generative design, through the aggregation of many small contributions, is less clear. Although in recent years the “power of the crowd” has been repeatedly demonstrated in areas that range from image labelling to linguistic translation. The application of crowdsourcing in the fields of design research and creative innovation has been much slower to emerge. As a result, although there have been reports of systems and researchers using Internet crowdsourcing to carry out generative design, there are still many gaps in knowledge about the capability and limitations of the technology. For example on commercial crowdsourcing platforms, the relationship between remuneration and the final quality of designs has not been established, so it is unclear how much payment should be offered in order to ensure a particular standard of result. Key to investigating the relationship between the crowd’s remuneration and the value of their innovation is a robust method for quantifying the quality of the designs produced. This paper reports how payment for a design task (a 2D layout problem) was systematically varied and the quality of the output assessed through a separate crowdsourcing process. The work provides some interesting and valuable insight into how Crowdsourcing can be most effectively employed in design tasks.

scholarly journals Crowdsensing Influences and Error Sources in Urban Outdoor Wi-Fi Fingerprinting Positioning

Sensors ◽  
2020 ◽  
Vol 20 (2) ◽  
pp. 427 ◽  
Author(s):  
Cristian-Liviu Leca ◽  
Ioan Nicolaescu ◽  
Petrica Ciotirnae
Keyword(s):  
Signal Strength ◽  
Location Based Services ◽  
Valuable Insight ◽  
Positioning System ◽  
Indoor Environments ◽  
Error Sources ◽  
Positioning Systems ◽  
Long Time ◽  
Insight Into

Wi-Fi fingerprinting positioning systems have been deployed for a long time in location-based services for indoor environments. Combining mobile crowdsensing and Wi-Fi fingerprinting systems could reduce the high cost of collecting the necessary data, enabling the deployment of the resulting system for outdoor positioning in areas with dense Wi-Fi coverage. In this paper, we present the results attained in the design and evaluation of an urban fingerprinting positioning system based on crowdsensed Wi-Fi measurements. We first assess the quality of the collected measurements, highlighting the influence of received signal strength on data collection. We then evaluate the proposed system by comparing the influence of the crowdsensed fingerprints on the overall positioning accuracy for different scenarios. This evaluation helps gain valuable insight into the design and deployment of urban Wi-Fi positioning systems while also allowing the proposed system to match GPS-like accuracy in similar conditions.

scholarly journals Athlete Self-Report Measures in Research and Practice: Considerations for the Discerning Reader and Fastidious Practitioner

2017 ◽  
Vol 12 (s2) ◽  
pp. S2-127-S2-135 ◽  
Author(s):  
Anna E. Saw ◽  
Michael Kellmann ◽  
Luana C. Main ◽  
Paul B. Gastin
Keyword(s):  
Psychometric Properties ◽  
Self Report ◽  
Valuable Insight ◽  
Research Papers ◽  
Empirical Measures ◽  
Research And Practice ◽  
Training Response ◽  
Insight Into

Athlete self-report measures (ASRM) have the potential to provide valuable insight into the training response; however, there is a disconnect between research and practice that needs to be addressed; namely, the measure or methods used in research are not always reflective of practice, or data primarily obtained from practice lacks empirical quality. This commentary reviews existing empirical measures and the psychometric properties required to be considered acceptable for research and practice. This information will allow discerning readers to make a judgment on the quality of ASRM data being reported in research papers. Fastidious practitioners and researchers are also provided with explicit guidelines for selecting and implementing an ASRM and reporting these details in research papers.

Physical Health

2019 ◽  
pp. 22-65
Keyword(s):  
Risk Factors ◽  
Adolescent Health ◽  
Future Generations ◽  
Major Constituent ◽  
Valuable Insight ◽  
South East Asia ◽  
Health Issues ◽  
East Asia Region ◽  
Insight Into

Though adolescence is relatively a healthier period of life as compared to childhood, several risk factors of adult diseases having their onset during adolescence can be prevented with proper interventions during this period, though with many challenges. Data on the health and nutritional status of adolescents is of vital importance not merely in the context of improving the quality of their lives but also for providing valuable insight into issues that are likely to have profound bearing on the future generations. However, the exclusive data pertaining to the adolescent health issues in Indian scenario is not available as compared to other nations. Hence, the data pertaining to South East Asia region for comparison has been referred to, in which India is a major constituent country. The data about important adolescent health issues in different areas is scarce. Hence, detailed investigation of the incidence and interventions on adolescent health issues is the need of the hour.

scholarly journals Crowdsensing Influences and Error Sources in Urban Wi-Fi Fingerprinting Positioning

2019 ◽  
Author(s):  
Cristian-Liviu Leca ◽  
Ioan Nicolaescu ◽  
Petrica Ciotirnae
Keyword(s):  
Signal Strength ◽  
Location Based Services ◽  
Valuable Insight ◽  
Positioning System ◽  
Indoor Environments ◽  
Error Sources ◽  
Positioning Systems ◽  
Long Time ◽  
Insight Into

Wi-Fi fingerprinting positioning systems have been deployed for a long time in location-based services for indoor environments. Combining mobile crowdsensing and Wi-Fi fingerprinting systems could reduce the high cost for collecting the necessary data enabling the deployment of the resulting system for outdoor positioning in areas with dense Wi-Fi coverage. In this paper, we present the results attained in the designing and evaluation of an urban fingerprinting positioning system based on crowdsensed Wi-Fi measurements. We first asses the quality of the collected measurements, highlighting the influence of received signal strength on data collection. We then, evaluate the proposed system by comparing the influence of the crowdsensed fingerprints on the overall positioning accuracy for different scenarios. The evaluation helps gain valuable insight into the design and deployment of urban Wi-Fi positioning systems while also allowing the proposed system to match GPS-like accuracy in similar conditions.

Minimization of the Variance in Oil-Film Damping Coefficient Estimates

1984 ◽  
Vol 106 (4) ◽  
pp. 342-349 ◽  
Author(s):  
M. N. Sahinkaya ◽  
O. S. Turkay ◽  
C. R. Burrows
Keyword(s):  
Data Analysis ◽  
Least Squares ◽  
Squeeze Film ◽  
Coefficient Estimates ◽  
Confidence Bounds ◽  
Experimental Procedure ◽  
Oil Film ◽  
Analysis Package ◽  
Correct Design

The frequency-domain algorithm developed by the authors to estimate oil-film bearing coefficients uses a Least Squares estimator and produces the variances and confidence bounds for the estimates. The variances can be minimized by correct design of the experimental procedure as well as by the data analysis package. The coefficient estimates are obtained by applying a multi-frequency test signal, measuring the applied force and corresponding journal displacements along orthogonal axes, and implementing the estimator. The paper discusses the use of D-optimality to select the measurement axes to improve the quality of the estimates. Experimental results obtained from a squeeze-film bearing rig are presented and discussed.

Study of the resistor material of an automotive spark plug by use of the charge-up effect along with elemental mapping in an electron microprobe

1991 ◽  
Vol 49 ◽  
pp. 742-743
Author(s):  
D. R. Liu ◽  
S. S. Shinozaki ◽  
J. S. Park ◽  
B. N. Juterbock
Keyword(s):  
Electron Microprobe ◽  
Present Report ◽  
Coated Sample ◽  
Valuable Insight ◽  
Elemental Mapping ◽  
Spark Plug ◽  
Carbon Coated ◽  
Electron Image ◽  
Electron Imaging ◽  
Insight Into

The electric and thermal properties of the resistor material in an automotive spark plug should be stable during its service lifetime. Containing many elements and many phases, this material has a very complex microstructure. Elemental mapping with an electron microprobe can reveal the distribution of all relevant elements throughout the sample. In this work, it is demonstrated that the charge-up effect, which would distort an electron image and, therefore, is normally to be avoided in an electron imaging work, could be used to advantage to reveal conductive and resistive zones in a sample. Its combination with elemental mapping can provide valuable insight into the underlying conductivity mechanism of the resistor.This work was performed in a CAMECA SX-50 microprobe. The spark plug used in the present report was a commercial product taken from the shelf. It was sectioned to expose the cross section of the resistor. The resistor was known not to contain the precious metal Au as checked on the carbon coated sample. The sample was then stripped of carbon coating and re-coated with Au.

Quantum Mechanical Interpretation of the Ultra-Low Energy Methyl-Rotation Dynamics in Porous Metal-Organic Frameworks Probed by Low-Frequency Vibrational Spectroscopy and ab initio Simulations

2018 ◽  
Author(s):  
Qi Li ◽  
Adam J. Zaczek ◽  
Timothy M. Korter ◽  
J. Axel Zeitler ◽  
Michael T. Ruggiero
Keyword(s):  
Ab Initio ◽  
Metal Organic Frameworks ◽  
Low Frequency ◽  
Rotor Dynamics ◽  
Quantum Mechanical ◽  
Valuable Insight ◽  
Void Space ◽  
Ab Initio Simulations ◽  
Metal Organic ◽  
Insight Into

<div>Understanding the nature of the interatomic interactions present within the pores of metal-organic frameworks</div><div>is critical in order to design and utilize advanced materials</div><div>with desirable applications. In ZIF-8 and its cobalt analogue</div><div>ZIF-67, the imidazolate methyl-groups, which point directly</div><div>into the void space, have been shown to freely rotate - even</div><div>down to cryogenic temperatures. Using a combination of ex-</div><div>perimental terahertz time-domain spectroscopy, low-frequency</div><div>Raman spectroscopy, and state-of-the-art ab initio simulations,</div><div>the methyl-rotor dynamics in ZIF-8 and ZIF-67 are fully charac-</div><div>terized within the context of a quantum-mechanical hindered-</div><div>rotor model. The results lend insight into the fundamental</div><div>origins of the experimentally observed methyl-rotor dynamics,</div><div>and provide valuable insight into the nature of the weak inter-</div><div>actions present within this important class of materials.</div>

A Review of Phytochemical and Pharmacological Studies of Inula Species

2020 ◽  
Vol 16 (5) ◽  
pp. 557-567
Author(s):  
Aparoop Das ◽  
Anshul Shakya ◽  
Surajit Kumar Ghosh ◽  
Udaya P. Singh ◽  
Hans R. Bhat
Keyword(s):  
Bacterial Infections ◽  
Chemical Constituents ◽  
Valuable Insight ◽  
Important Ingredient ◽  
Pharmacological Activities ◽  
Medicinal Uses ◽  
The Family ◽  
Pharmacological Studies ◽  
Perennial Herbs ◽  
Insight Into

Background: Plants of the genus Inula are perennial herbs of the family Asteraceae. This genus includes more than 100 species, widely distributed throughout Europe, Africa and Asia including India. Many of them are indicated in traditional medicine, e.g., in Ayurveda. This review explores chemical constituents, medicinal uses and pharmacological actions of Inula species. Methods: Major databases and research and review articles retrieved through Scopus, Web of Science, and Medline were consulted to obtain information on the pharmacological activities of the genus Inula published from 1994 to 2017. Results: Inula species are used either alone or as an important ingredient of various formulations to cure dysfunctions of the cardiovascular system, respiratory system, urinary system, central nervous system and digestive system, and for the treatment of asthma, diabetes, cancers, skin disorders, hepatic disease, fungal and bacterial infections. A range of phytochemicals including alkaloids, essential and volatile oils, flavonoids, terpenes, and lactones has been isolated from herbs of the genus Inula, which might possibly explain traditional uses of these plants. Conclusion: The present review is focused on chemical constituents, medicinal uses and pharmacological actions of Inula species and provides valuable insight into its medicinal potential.

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