Load Control–Strain Control Isochronous Stress–Strain Curves for High Temperature Nonlinear Analysis

1995 ◽  
Vol 117 (2) ◽  
pp. 364-370 ◽  
Author(s):  
G. S. Bechtel ◽  
T. S. Cook
Keyword(s):  
Rupture Life ◽  
Nonlinear Behavior ◽  
General Purpose ◽  
Operating Conditions ◽  
Time Dependent ◽  
Load Control ◽  
New Techniques ◽  
Time Stepping ◽  
The Past ◽  
Computer Resources

Aircraft gas turbine components are subjected to severe operating conditions. High temperatures, large thermal strains, and mechanical loads combine to cause the material to undergo significant nonlinear behavior. In order to assure safe, durable components, it is necessary that analysis methods be available to predict the nonlinear deformation. General purpose finite element codes are available to perform elastic and viscoplastic analyses, but the analyses are expensive. Both large plastic and creep strain analyses can require significant computer resources, but typically a plastic solution is more economical to run than a time-stepping creep or viscoplastic model solution. For those applications where the deformation is principally time dependent, it is advantageous to include time-dependent creep effects in a “constant time” or “isochronous” analysis. Although this approach has been used in the past to estimate rupture life, this paper will present several significant new techniques for doing an isochronous analysis to analyze time-dependent deformation.

scholarly journals Load Control–Strain Control Isochronous Stress–Strain Curves for High Temperature Nonlinear Analysis

1993 ◽  
Author(s):  
Gregory S. Bechtel ◽  
Thomas S. Cook
Keyword(s):  
Rupture Life ◽  
Nonlinear Behavior ◽  
General Purpose ◽  
Operating Conditions ◽  
Time Dependent ◽  
Load Control ◽  
New Techniques ◽  
Time Stepping ◽  
The Past ◽  
Computer Resources

Aircraft gas turbine components are subjected to severe operating conditions. High temperatures, large thermal strains, and mechanical loads combine to cause the material to undergo significant nonlinear behavior. In order to assure safe, durable components, it is necessary that analysis methods be available to predict the nonlinear deformation. General purpose finite element codes are available to perform elastic and viscoplastic analyses, but the analyses are expensive. Both large plastic and creep strain analyses can require significant computer resources, but typically a plastic solution is more economical to run than a time stepping creep or viscoplastic model solution. For those applications where the deformation is principally time dependent, it is advantageous to include time dependent creep effects in a “constant time” or “isochronous” analysis. Although this approach has been used in the past to estimate rupture life, this paper will present several significant new techniques for doing an isochronous analysis to analyze time dependent deformation.

Archaeology and Television

Antiquity ◽  
1954 ◽  
Vol 28 (112) ◽  
pp. 201-205 ◽  
Author(s):  
Glyn E. Daniel
Keyword(s):  
General Purpose ◽  
The West ◽  
New Techniques ◽  
The Third ◽  
The Past ◽  
West Region ◽  
Home Service ◽  
New Ideas

Serious and sustained archaeological broadcasting began only after the end of the 1939-45 War. It was the result of the general purpose of the S Third Programme and the particular endeavour of the West Region in the persons of Frank Gillard, Head of Programmes at Bristol, and Gilbert Phelps, one of the talks producers there. There had of course been archaeological broadcasts in the pre-war years, and Sir Leonard Woolley’s best-selling Digging up the Past began as a series of talks ; but it was not until The Archaeologist was created by the West Region, and taken over, first by the Third Programme—it was actually the first series of talks to appear on that programme—and then by the Home Service, that archaeology began to have a recognised and acceptable place in sound broadcasting. There have been plenty of archaeological broadcasts outside this series, and so there should be ; but it was the existence of a regular series providing for the discussion of current discoveries, new techniques and new ideas and demanding thought on the part of producers and editors that, to my mind, really put archaeological broadcasting on the B.B.C. map.

Stellar Evolution

1962 ◽  
Vol 11 (02) ◽  
pp. 137-143
Author(s):  
M. Schwarzschild
Keyword(s):  
Solar System ◽  
Stellar Evolution ◽  
Space Craft ◽  
New Techniques ◽  
Substantial Body ◽  
Individual Stars ◽  
The Past ◽  
Evolution Of Galaxies ◽  
History Of ◽  
Fast Flow

It is perhaps one of the most important characteristics of the past decade in astronomy that the evolution of some major classes of astronomical objects has become accessible to detailed research. The theory of the evolution of individual stars has developed into a substantial body of quantitative investigations. The evolution of galaxies, particularly of our own, has clearly become a subject for serious research. Even the history of the solar system, this close-by intriguing puzzle, may soon make the transition from being a subject of speculation to being a subject of detailed study in view of the fast flow of new data obtained with new techniques, including space-craft.

scholarly journals Sixty Years with the Chrysobalanaceae

2020 ◽  
Author(s):  
Ghillean T. Prance
Keyword(s):  
Economic Botany ◽  
Field Studies ◽  
Molecular Evidence ◽  
New Techniques ◽  
Conservation Ecology ◽  
The Past ◽  
New Findings ◽  
The Family ◽  
Molecular Studies ◽  
Economic Use

AbstractA review is given of the studies of Ghillean Prance and associates on the Chrysobalanaceae over the past sixty years. This has focussed on defining the generic boundaries in the family and on monographic work with a worldwide approach to this pantropical family. The importance of field studies for work on monographs and Floras is emphasized. Monographs are still the basis for much work on conservation, ecology and economic botany and are needed as a foundation for molecular studies. The importance of being open to experimenting with new techniques and as a result being willing to change the taxonomy in accordance with new findings is demonstrated and emphasized. The twelve genera of the Chrysobalanaceae at the beginning of this career-long study have now increased to twenty-eight in order to present a much better monophyletic and evolutionary arrangement based on recent molecular evidence. In particular it was necessary to divide and rearrange the originally large genera Parinari and Licania into a number of smaller segregate genera. All known species were included in a worldwide monograph published in 2003. A brief review of the economic use for the family is given.

scholarly journals On the Lifetime Estimation of SiC Power MOSFETs for Motor Drive Applications

Electronics ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 324
Author(s):  
Carmelo Barbagallo ◽  
Santi Agatino Rizzo ◽  
Giacomo Scelba ◽  
Giuseppe Scarcella ◽  
Mario Cacciato
Keyword(s):  
Electric Drive ◽  
Average Power ◽  
Estimation Procedure ◽  
General Purpose ◽  
Operating Conditions ◽  
Power Losses ◽  
Power Devices ◽  
Lifetime Estimation ◽  
Power Mosfets ◽  
Mission Profile

This work presents a step-by-step procedure to estimate the lifetime of discrete SiC power MOSFETs equipping three-phase inverters of electric drives. The stress of each power device when it is subjected to thermal jumps from a few degrees up to about 80 °C was analyzed, starting from the computation of the average power losses and the commitment of the electric drive. A customizable mission profile was considered where, by accounting the working conditions of the drive, the corresponding average power losses and junction temperatures of the SiC MOSFETs composing the inverter can be computed. The tool exploits the Coffin–Manson theory, rainflow counting, and Miner’s rule for the lifetime estimation of the semiconductor power devices. Different operating scenarios were investigated, underlying their impact on the lifetime of SiC MOSFETs devices. The lifetime estimation procedure was realized with the main goal of keeping limited computational efforts, while providing an effective evaluation of the thermal effects. The method enables us to set up any generic mission profile from the electric drive model. This gives us the possibility to compare several operating scenario of the drive and predict the worse operating conditions for power devices. Finally, although the lifetime estimation tool was applied to SiC power MOSFET devices for a general-purpose application, it can be extended to any type of power switch technology.

scholarly journals Time Dependent Gene Expression Changes in the Liver of Mice Treated with Benzene

2008 ◽  
Vol 3 ◽  
pp. BMI.S590 ◽  
Author(s):  
Han-Jin Park ◽  
Jung Hwa Oh ◽  
Seokjoo Yoon ◽  
S.V.S. Rana
Keyword(s):  
Gene Expression ◽  
Expression Profiles ◽  
Gene Expression Profiles ◽  
General Purpose ◽  
Time Dependent ◽  
Expression Data ◽  
Benzene Exposure ◽  
Microarray Analyses ◽  
First Time ◽  
Affymetrix Gene Chip

Benzene is used as a general purpose solvent. Benzene metabolism starts from phenol and ends with p-benzoquinone and o-benzoquinone. Liver injury inducted by benzene still remains a toxicologic problem. Tumor related genes and immune responsive genes have been studied in patients suffering from benzene exposure. However, gene expression profiles and pathways related to its hepatotoxicity are not known. This study reports the results obtained in the liver of BALB/C mice (SLC, Inc., Japan) administered 0.05 ml/100 g body weight of 2% benzene for six days. Serum, ALT, AST and ALP were determined using automated analyzer (Fuji., Japan). Histopathological observations were made to support gene expression data. c-DNA microarray analyses were performed using Affymetrix Gene-chip system. After six days of benzene exposure, twenty five genes were down regulated whereas nineteen genes were up-regulated. These gene expression changes were found to be related to pathways of biotransformation, detoxification, apoptosis, oxidative stress and cell cycle. It has been shown for the first time that genes corresponding to circadian rhythms are affected by benzene. Results suggest that gene expression profile might serve as potential biomarkers of hepatotoxicity during benzene exposure.

scholarly journals A Flexible Load Control Strategy for Distribution Network to Reduce the Line Losses and to Eliminate the Transmission Congestion

2017 ◽  
Vol 2017 ◽  
pp. 1-16 ◽  
Author(s):  
Beibei Wang ◽  
Xiaoqing Hu ◽  
Peifeng Shen ◽  
Wenlu Ji ◽  
Yang Cao ◽  
...  
Keyword(s):  
Power Distribution ◽  
Distribution Systems ◽  
Renewable Energy Sources ◽  
Distribution Network ◽  
Test System ◽  
Operating Conditions ◽  
Load Control ◽  
Transmission Congestion ◽  
Heavy Load ◽  
Flexible Load

There are many uncertain factors in the modern distribution network, including the access of renewable energy sources and the heavy load level. The existence of these factors has brought challenges to the stability of the power distribution network, as well as increasing the risk of exceeding transmission capacity of distribution lines. The appearance of flexible load control technology provides a new idea to solve the above problems. Air conditioners (ACs) account for a great proportion of all loads. In this paper, the model of dispatching AC loads in the regional power grid is constructed, and the direct load control (DLC) method is adopted to reduce the load of ACs. An improved tabu search technique is proposed to solve the problem of network dispatch in distribution systems in order to reduce the resistive line losses and to eliminate the transmission congestion in lines under normal operating conditions. The optimal node solution is obtained to find the best location and reduction capacity of ACs for load control. To demonstrate the validity and effectiveness of the proposed method, a test system is studied. The numerical results are also given in this article, which reveal that the proposed method is promising.

Dynamical theory of neutron diffraction

1978 ◽  
Vol 56 (10) ◽  
pp. 1261-1288 ◽  
Author(s):  
V. F. Sears
Keyword(s):  
Neutron Diffraction ◽  
Theoretical Basis ◽  
Dynamical Theory ◽  
Experimental Results ◽  
Neutron Interferometry ◽  
New Techniques ◽  
The Past ◽  
Neutron Optics ◽  
Coherent Wave ◽  
Special Cases

We present a review of the dynamical theory of neutron diffraction by macroscopic bodies which provides the theoretical basis for the study of neutron optics. We consider both the theory of dispersion, in which it is shown that the coherent wave in the medium satisfies a macroscopic one-body Schrödinger equation, and the theory of reflection, refraction, and diffraction in which the above equation is solved for a number of special cases of interest. The theory is illustrated with the help of experimental results obtained over the past 10 years by a number of new techniques such as neutron gravity refractometry, Pendellösung interference, and neutron interferometry.

THE ORIGINS OF MUSIC: INNATENESS, UNIQUENESS, AND EVOLUTION

2005 ◽  
Vol 23 (1) ◽  
pp. 29-59 ◽  
Author(s):  
JOSH McDERMOTT ◽  
MARC HAUSER
Keyword(s):  
Side Effects ◽  
Music Perception ◽  
Comparative Psychology ◽  
General Purpose ◽  
Adaptive Significance ◽  
Future Research ◽  
Relative Pitch ◽  
The Past ◽  
Evolution Of Music ◽  
Basic Features

THE ORIGINS and adaptive significance of music, long an elusive target, are now active topics of empirical study, with many interesting developments over the past few years. This article reviews research in anthropology, ethnomusicology, developmental and comparative psychology, neuropsychology, and neurophysiology that bears on questions concerning the origins and evolution of music. We focus on the hypothesis that music perception is constrained by innate, possibly human- and musicspecific principles of organization, as these are candidates for evolutionary explanations. We begin by discussing the distinct roles of different fields of inquiry in constraining claims about innateness and adaptation, and then proceed to review the available evidence. Although research on many of these topics is still in its infancy, at present there is converging evidence that a few basic features of music (relative pitch, the importance of the octave, intervals with simple ratios, tonality, and perhaps elementary musical preferences) are determined in part by innate constraints. At present, it is unclear how many of these constraints are uniquely human and specific to music. Many, however, are unlikely to be adaptations for music, but rather are probably side effects of more general-purpose mechanisms. We conclude by reiterating the significance of identifying processes that are innate, unique to humans, and specific to music, and highlight several possible directions for future research.

The Motion of Floating Systems: Nonlinear Dynamics in Periodic and Random Waves

2009 ◽  
Vol 131 (4) ◽  
Author(s):  
Katrin Ellermann
Keyword(s):  
Dynamical Behavior ◽  
Nonlinear Behavior ◽  
Operating Conditions ◽  
Random Waves ◽  
Multiple Components ◽  
Random Disturbances ◽  
Restoring Forces ◽  
Steady State Responses ◽  
External Forces ◽  
Floating Systems

Floating systems, such as ships, barges, or semisubmersibles, show a dynamical behavior, which is determined by their internal structure and the operating conditions caused by external forces e.g., due to waves and wind. Due to the complexity of the system, which commonly includes coupling of multiple components or nonlinear restoring forces, the response can exhibit inherently nonlinear characteristics. In this paper different models of floating systems are considered. For the idealized case of purely harmonic forcing they all show nonlinear behavior such as subharmonic motion or different steady-state responses at constant operating conditions. The introduction of random disturbances leads to deviations from the idealized case, which may change the overall response significantly. Advantages and limitations of the different mathematical models and the applied numerical techniques are discussed.

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