scholarly journals The Effect of Blade Discretization on Resonant Turbine Blade Response

1983 ◽  
Author(s):  
Chia-Fu Sheng ◽  
John G. Mosimann
Keyword(s):  
Turbine Blade ◽  
Timoshenko Beam ◽  
Energy Method ◽  
Lumped Mass ◽  
Ideal Case ◽  
Higher Modes ◽  
The Ideal

The two methods currently used in industry to calculate blade resonant responses, the energy method and the transmissibility method, are discussed relative to accuracy and facility. Although identical in form for the ideal case, the methods differ in accuracy for practical cases depending on discretization, i.e., model lumped mass breakup fineness. For clarity, the equations for these two methods are derived for a Timoshenko beam and solved numerically for a beam with varying discretization. The results show resonant stress differences up to 30% for higher modes using limited but equal discretization, proving the practical superiority of the energy method over the transmissibility method by example as well as by theory.

Criteria and Methods for Reliable Three-Dimensional Image Reconstruction

1974 ◽  
Vol 32 ◽  
pp. 330-331
Author(s):  
R. A. Crowther
Keyword(s):  
Image Reconstruction ◽  
Finite Number ◽  
Density Distribution ◽  
Electron Micrographs ◽  
Mathematical Problem ◽  
Three Dimensional ◽  
Ideal Case ◽  
Dimensional Image ◽  
General Object ◽  
The Ideal

The reconstruction of a three-dimensional image of a specimen from a set of electron micrographs reduces, under certain assumptions about the imaging process in the microscope, to the mathematical problem of reconstructing a density distribution from a set of its plane projections.In the absence of noise we can formulate a purely geometrical criterion, which, for a general object, fixes the resolution attainable from a given finite number of views in terms of the size of the object. For simplicity we take the ideal case of projections collected by a series of m equally spaced tilts about a single axis.

The DQE of an electron image recording system

1978 ◽  
Vol 36 (1) ◽  
pp. 100-101
Author(s):  
K.-H. Herrmann ◽  
D. Krahl ◽  
H.-P Rust
Keyword(s):  
Primary Electron ◽  
Ideal Case ◽  
Image Recording ◽  
Main Requirement ◽  
High Detection ◽  
Electron Image ◽  
Video Amplifier ◽  
Detection Quantum Efficiency ◽  
Selection Of ◽  
The Ideal

The high detection quantum efficiency (DQE) is the main requirement for an imagerecording system used in electron microscopy of radiation-sensitive specimens. An electronic TV system of the type shown in Fig. 1 fulfills these conditions and can be used for either analog or digital image storage and processing [1], Several sources of noise may reduce the DQE, and therefore a careful selection of various elements is imperative.The noise of target and of video amplifier can be neglected when the converter stages produce sufficient target electrons per incident primary electron. The required gain depends on the type of the tube and also on the type of the signal processing chosen. For EBS tubes, for example, it exceeds 10. The ideal case, in which all impinging electrons create uniform charge peaks at the target, is not obtainable for several reasons, and these will be discussed as they relate to a system with a scintillator, fiber-optic and photo-cathode combination as the first stage.

Seismic response and retrofit of industrial brick masonry chimneys

1992 ◽  
Vol 19 (1) ◽  
pp. 117-128 ◽  
Author(s):  
A. Ghobarah ◽  
T. Baumber
Keyword(s):  
Seismic Response ◽  
Ground Motion ◽  
Strong Motion ◽  
Brick Masonry ◽  
Wind Loading ◽  
Earthquake Ground Motion ◽  
Lumped Mass ◽  
Mass System ◽  
Higher Modes ◽  
Recent Earthquakes

During recent earthquakes, the documented cases of collapsed unreinforced brick masonry industrial chimneys are numerous. Observed modes of structural failure are either total collapse or sometimes collapse or damage of the top third of the structure. The objective of this study is to analyze and explain the modes of observed failure of masonry chimneys during earthquake events, and to evaluate two retrofit systems for existing chimneys in areas of high seismicity. The behaviour of the masonry chimney, when subjected to earthquake ground motion, was modelled using a lumped mass system. Several actual strong motion records were used as input to the model. The shear, moment, and displacement responses to the earthquake ground motion were evaluated for various chimney configurations. It was found that the failure of the chimney at its base is the result of the fundamental mode of vibration. Failure at the top third of the structure due to the higher modes of vibration is possible when the chimney is subjected to high frequency content earthquakes. Higher modes, which are normally not of concern under wind loading, were shown to be critical in seismic design. Post-tensioning and the reinforcing steel cage were found to be effective retrofit systems. Key words: masonry, chimneys, behaviour, analysis, design, retrofit, dynamic, earthquakes, seismic response.

Generalization, similarity, and Bayesian inference

2001 ◽  
Vol 24 (4) ◽  
pp. 629-640 ◽  
Author(s):  
Joshua B. Tenenbaum ◽  
Thomas L. Griffiths
Keyword(s):  
Natural Kinds ◽  
Explanatory Power ◽  
Theoretic Model ◽  
Decay Function ◽  
Ideal Case ◽  
Basic Assumptions ◽  
Realistic Situation ◽  
Wide Range ◽  
Universal Law ◽  
The Ideal

Shepard has argued that a universal law should govern generalization across different domains of perception and cognition, as well as across organisms from different species or even different planets. Starting with some basic assumptions about natural kinds, he derived an exponential decay function as the form of the universal generalization gradient, which accords strikingly well with a wide range of empirical data. However, his original formulation applied only to the ideal case of generalization from a single encountered stimulus to a single novel stimulus, and for stimuli that can be represented as points in a continuous metric psychological space. Here we recast Shepard's theory in a more general Bayesian framework and show how this naturally extends his approach to the more realistic situation of generalizing from multiple consequential stimuli with arbitrary representational structure. Our framework also subsumes a version of Tversky's set-theoretic model of similarity, which is conventionally thought of as the primary alternative to Shepard's continuous metric space model of similarity and generalization. This unification allows us not only to draw deep parallels between the set-theoretic and spatial approaches, but also to significantly advance the explanatory power of set-theoretic models.

Introduction

2021 ◽  
pp. 3-24
Author(s):  
Levy O’Flynn.
Keyword(s):  
Ideal Case ◽  
Peace Settlement ◽  
The Ideal

Referendums are now common in ‘conflict societies’—societies where a widespread and concerted campaign of violence between groups recently occurred, is occurring, or is liable to occur. In the ideal case, a peace referendum can secure consent for a new formal peace settlement among warring groups and provide the settlement with a popular mandate. In practice, however, settlements, once attained, may struggle to endure. Some may collapse entirely. Against this background we introduced what we call the ‘Deliberative Peace Referendum’, or ‘DPR’. A DPR is a purpose-designed deliberative referendum held under conditions of conflict. As this chapter recognizes, designing a referendum to be more deliberative is a challenge under any circumstances. It may be hardest of all amid armed intercommunal conflict.

From Constitutionalism to War—and Back Again

2021 ◽  
pp. 229-334
Author(s):  
Arthur Ripstein
Keyword(s):  
War And Peace ◽  
Ideal Case ◽  
Kantian Theory ◽  
Theory Of War ◽  
The Ideal

This chapter presents Arthur Ripstein’s responses to the authors of the preceding chapters. The chapter follows the order of the contributions, and are divided broadly into responses to the papers in Part I concerning the ways in which facts matter to right, and the relation between the flawed world in which we find ourselves and the ideal case that Kant contemplates, and to those in Part II dealing with more specific issues in the Kantian theory of war and peace.

Practical Design of 4H-SiC Superjunction Devices in the Presence of Charge Imbalance

2018 ◽  
Vol 924 ◽  
pp. 563-567
Author(s):  
Md Monzurul Alam ◽  
Dallas T. Morisette ◽  
James A. Cooper
Keyword(s):  
Drift Region ◽  
Charge Balance ◽  
Ideal Case ◽  
Charge Imbalance ◽  
Blocking Voltage ◽  
Practical Design ◽  
Proper Design ◽  
Improved Performance ◽  
The Relationship ◽  
The Ideal

In the ideal case, superjunction (SJ) drift regions theoretically exhibit a linear relationship between specific-on resistance Ron,sp and blocking voltage VBR, but this requires perfect charge balance between the alternating n and p pillars. If any degree of imbalance exists, the relationship becomes quadratic, similar to a conventional drift region, although with somewhat improved performance. In this work, we analyze superjunction drift regions in 4H-SiC under realistic degrees of charge imbalance and show that, with proper design, a reduction in specific on-resistance of 2~10x is possible as long as the imbalance remains less than ±20%.

scholarly journals Influence of surface roughness on diffraction in the externally occulted Lyot solar coronagraph

2019 ◽  
Vol 626 ◽  
pp. A1
Author(s):  
R. Rougeot ◽  
R. Flamary ◽  
D. Mary ◽  
C. Aime
Keyword(s):  
Wave Propagation ◽  
Solar Radius ◽  
Diffraction Peak ◽  
Propagation Model ◽  
Ideal Case ◽  
Power Spectral ◽  
Scattering Effects ◽  
Order Of Magnitude ◽  
Micro Structures ◽  
The Ideal

Context. The solar coronagraph ASPIICS will fly on the future ESA formation flying mission Proba-3. The instrument combines an external occulter of diameter 1.42 m and a Lyot solar coronagraph of 5 cm diameter, located downstream at a distance of 144 m. Aims. The theoretical performance of the externally occulted Lyot coronagraph has been computed by assuming perfect optics. In this paper, we improve related modelling by introducing roughness scattering effects from the telescope. We have computed the diffraction at the detector, that we compare to the ideal case without perturbation to estimate the performance degradation. We have also investigated the influence of sizing the internal occulter and the Lyot stop, and we performed a sensitivity analysis on the roughness. Methods. We have built on a recently published numerical model of diffraction propagation. The micro-structures of the telescope are built by filtering a white noise with a power spectral density following an isotropic ABC function, suggested by Harvey scatter theory. The parameters were tuned to fit experimental data measured on ASPIICS lenses. The computed wave front error was included in the Fresnel wave propagation of the coronagraph. A circular integration over the solar disk was performed to reconstruct the complete diffraction intensity. Results. The level of micro-roughness is 1.92 nm root-mean-square. Compared to the ideal case, in the plane of the internal occulter, the diffraction peak intensity is reduced by ≃0.001%. However, the intensity outside the peak increases by 12% on average, up to 20% at 3 R⊙, where the mask does not filter out the diffraction. At detector level, the diffraction peak remains ≃10−6 at 1.1 R⊙, similar to the ideal case, but the diffraction tail at large solar radius is much higher, up to one order of magnitude. Sizing the internal occulter and the Lyot stop does not improve the rejection, as opposed to the ideal case. Conclusions. Besides these results, this paper provides a methodology to implement roughness scattering in the wave propagation model for the solar coronagraph.

Performance Simulation of the SCTP under the Multi Path Environment

2015 ◽  
Vol 738-739 ◽  
pp. 1174-1177
Author(s):  
Ya Qin Fan ◽  
Shu Ting Liu ◽  
Chi Li
Keyword(s):  
Practical Significance ◽  
Practical Implementation ◽  
Ideal Case ◽  
Performance Simulation ◽  
Tcp Protocol ◽  
Multiple Paths ◽  
Multiple Network ◽  
Basic Features ◽  
Basic Standard ◽  
The Ideal

This paper studies the basic features and functions of STCP. The traditional TCP protocol and the basic standard SCTP protocols are simulated respectively. We analysis that when the host has multiple network addresses and there are multiple paths between ends, how do the STCP protocol and TCP protocol perform. For practical implementation, using CWND size parameters show performance of multi path transmission in practice, and compare with the ideal case. The results of the simulation and analysis of multi path transmission under the SCTP agreement have practical significance in the future network with multi path transmission.

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