An Improved Method for Calculating the Contribution of Hydrodynamic Chain Damping on Low-Frequency Vessel Motions

1992 ◽  
Author(s):  
Albertus Dercksen ◽  
R.H.M. Huijsmans ◽  
J.E.W. Wichers
Keyword(s):  
Low Frequency ◽  
Improved Method ◽  
Hydrodynamic Chain

An Improved Method of Short Text Feature Extraction Based on Words Co-Occurrence

2014 ◽  
Vol 519-520 ◽  
pp. 842-845 ◽  
Author(s):  
Li Hong Wang
Keyword(s):  
Feature Extraction ◽  
Chinese Text ◽  
Traditional Method ◽  
Low Frequency ◽  
Text Clustering ◽  
Improved Method ◽  
Short Text ◽  
Text Feature ◽  
Short Text Clustering

In Chinese text clustering, short text is very different from traditional long text, principally in the low frequency of words. As a result, traditional text feature extraction and the method for weight calculating is not directly suitable for short text clustering .To solve the problem of clustering drift in short text segments ,this paper proposes an method for feature extraction through improving the method of weight calculating based on words co-occurrence. Experiments show the method can get better performance in Chinese short-text clustering compared with the traditional method TF-IDF.

Stochastic Finite-Fault Simulation of the Ms 7.0 Lushan Earthquake Based on Frequency- and Distance-Dependent Radiation Patterns

2021 ◽  
Author(s):  
Tianjia Wang ◽  
Xu Xie ◽  
Longfei Ji
Keyword(s):  
Radiation Pattern ◽  
Ground Motion ◽  
Low Frequency ◽  
Time History ◽  
Lushan Earthquake ◽  
Radiation Patterns ◽  
Improved Method ◽  
High Frequencies ◽  
Finite Fault ◽  
Finite Fault Method

ABSTRACT The stochastic finite-fault method (EXSIM) has been extensively used for simulating ground motion at high frequencies. However, its poor performance in low-frequency simulations is a limiting factor that restricts its engineering application. Refining the representation of the radiation pattern in the finite-fault method is an effective strategy to improve low-frequency simulations; to this end, a frequency-dependent radiation pattern has been considered by several researchers. However, this strategy fails to provide an accurate simulation of seismic-wave propagation at distances beyond the near-fault region. Researchers have proposed various approaches for characterizing the radiation pattern variation with distance. This study introduces frequency- and distance-dependent radiation patterns of S waves to the EXSIM. The near-field acceleration records in the east–west and north–south directions of the 2013 Ms 7.0 Lushan earthquake were reconstructed. The proposed method was verified by: (1) comparing broadband simulation results obtained by the improved method with observed results, (2) conducting a misfit analysis to compare the model bias between the improved and original methods, and (3) comparing the observed and simulated peak ground acceleration data with the predicted values of the ground-motion prediction equations (GMPEs) to verify the effectiveness of the GMPEs in describing the regional ground-motion attenuation. The results indicated that the 5%-damped pseudo spectral accelerations at high frequencies (1–20 Hz) and acceleration time history simulated by the improved method were consistent with the observed values. Furthermore, the improved method effectively optimizes the simulation effect at low frequencies (0.05–1 Hz) compared with the original method. Thus, the improvement in the representation of the radiation pattern in EXSIM can better estimate broadband ground motion in the study area.

scholarly journals Improved EEMD-based standardization method for developing long tree-ring chronologies

2019 ◽  
Vol 31 (6) ◽  
pp. 2217-2224 ◽  
Author(s):  
Xianliang Zhang ◽  
Junxia Li ◽  
Xiaobo Liu ◽  
Zhenju Chen
Keyword(s):  
Tree Ring ◽  
Low Frequency ◽  
Mean Value ◽  
Segment Length ◽  
Standardization Method ◽  
Improved Method ◽  
Growth Trend ◽  
Average Growth ◽  
Climate Signals ◽  
The Mean

Abstract Long tree-ring chronologies can be developed by overlapping data from living trees with data from fossil trees through cross-dating. However, low-frequency climate signals are lost when standardizing tree-ring series due to the “segment length curse”. To alleviate the segment length curse and thus improve the standardization method for developing long tree-ring chronologies, here we first calculated a mean value for all the tree ring series by overlapping all of the tree ring series. The growth trend of the mean tree ring width (i.e., cumulated average growth trend of all the series) was determined using ensemble empirical mode decomposition. Then the chronology was developed by dividing the mean value by the growth trend of the mean value. Our improved method alleviated the problem of trend distortion. Long-term signals were better preserved using the improved method than in previous detrending methods. The chronologies developed using the improved method were better correlated with climate than those developed using conservative methods. The improved standardization method alleviates trend distortion and retains more of the low-frequency climate signals.

Performance Analysis of Frequency Hopping Communication System Synchronization

2011 ◽  
Vol 403-408 ◽  
pp. 2927-2930 ◽  
Author(s):  
Jian Zheng ◽  
Xin Yu Wei ◽  
Xiao Gang Ni
Keyword(s):  
Performance Analysis ◽  
Low Frequency ◽  
Project Design ◽  
Improved Method ◽  
Frequency Method ◽  
System Synchronization ◽  
Frequency Changes ◽  
Changes Over Time ◽  
System Time ◽  
Over Time

This paper studies a method based on synchronized prefix improved method, use a synchronous frequency method related to the system time (TOD) to generate the synchronization frequency, each synchronous frequency changes over time in constantly changing, thus protecting synchronous frequency, and sent low frequency TOD Is calculated out of the high TOD, which increases the difficulty of deciphering. the results of Performance Analysis show that TOD self-synchronizing synchronizing time is quick, the synchronized probability is big, good randomness, has met the project design anticipated requirements.

A Study on the Fine Structure of the Lateral Line Organ of the Sea Eel

1973 ◽  
Vol 31 ◽  
pp. 648-649
Author(s):  
K. Hama
Keyword(s):  
Fine Structure ◽  
Electron Microscope ◽  
Lateral Line ◽  
Low Frequency ◽  
Sensory Cells ◽  
Apical Surface ◽  
Voltage Electron ◽  
Sensory Epithelia ◽  
Low Frequency Vibration ◽  
Transmission Electron

The lateral line organs of the sea eel consist of canal and pit organs which are different in function. The former is a low frequency vibration detector whereas the latter functions as an ion receptor as well as a mechano receptor.The fine structure of the sensory epithelia of both organs were studied by means of ordinary transmission electron microscope, high voltage electron microscope and of surface scanning electron microscope.The sensory cells of the canal organ are polarized in front-caudal direction and those of the pit organ are polarized in dorso-ventral direction. The sensory epithelia of both organs have thinner surface coats compared to the surrounding ordinary epithelial cells, which have very thick fuzzy coatings on the apical surface.

Lectin Binding to Human Breast Tumor Cells

1976 ◽  
Vol 34 ◽  
pp. 34-35
Author(s):  
Robert E. Nordquist ◽  
J. Hill Anglin ◽  
Michael P. Lerner
Keyword(s):  
Carcinoma Cell ◽  
Ricinus Communis ◽  
Lectin Binding ◽  
Low Frequency ◽  
Breast Carcinoma Cell Line ◽  
Human Breast ◽  
Human Breast Tumor ◽  
Duct Carcinoma ◽  
Specific Antigens ◽  
Ricin Agglutinin

A human breast carcinoma cell line (BOT-2) was derived from an infiltrating duct carcinoma (1). These cells were shown to have antigens that selectively bound antibodies from breast cancer patient sera (2). Furthermore, these tumor specific antigens could be removed from the living cells by low frequency sonication and have been partially characterized (3). These proteins have been shown to be around 100,000 MW and contain approximately 6% hexose and hexosamines. However, only the hexosamines appear to be available for lectin binding. This study was designed to use Concanavalin A (Con A) and Ricinus Communis (Ricin) agglutinin for the topagraphical localization of D-mannopyranosyl or glucopyranosyl and D-galactopyranosyl or DN- acetyl glactopyranosyl configurations on BOT-2 cell surfaces.

Practical High Resolution Microscopy

1968 ◽  
Vol 26 ◽  
pp. 302-303
Author(s):  
P. A. Marsh ◽  
T. Mullens ◽  
D. Price
Keyword(s):  
High Resolution ◽  
Magnetic Fields ◽  
Low Frequency ◽  
Resolving Power ◽  
Careful Attention ◽  
Electron Microscopes ◽  
The Relationship ◽  
High Resolution Microscopy ◽  
New Facilities

It is possible to exceed the guaranteed resolution on most electron microscopes by careful attention to microscope parameters essential for high resolution work. While our experience is related to a Philips EM-200, we hope that some of these comments will apply to all electron microscopes.The first considerations are vibration and magnetic fields. These are usually measured at the pre-installation survey and must be within specifications. It has been our experience, however, that these factors can be greatly influenced by the new facilities and therefore must be rechecked after the installation is completed. The relationship between the resolving power of an EM-200 and the maximum tolerable low frequency interference fields in milli-Oerstedt is 10 Å - 1.9, 8 Å - 1.4, 6 Å - 0.8.

An Improved Method for the Preparation and TEM Examination of Sharp Pointed Tips used in APFIM and STM

1990 ◽  
Vol 48 (2) ◽  
pp. 102-103
Author(s):  
E.A. Fischione ◽  
P.E. Fischione ◽  
J.J. Haugh ◽  
M.G. Burke
Keyword(s):  
Atom Probe ◽  
Preparation Process ◽  
Improved Method ◽  
Ion Milling ◽  
Polishing Process ◽  
Probe Field ◽  
Scanning Tunnelling ◽  
Stm Tips ◽  
Tunnelling Microscopy ◽  
Ion Microscopy

A common requirement for both Atom Probe Field-Ion Microscopy (APFIM) and Scanning Tunnelling Microscopy (STM) is a sharp pointed tip for use as either the specimen (APFIM) or the probe (STM). Traditionally, tips have been prepared by either chemical or electropolishing techniques. Recently, ion-milling has been successfully employed in the production of APFIM tips [1]. Conventional electropolishing techniques are applicable to a wide variety of metals, but generally require careful manual adjustments during the polishing process and may also be time-consuming. In order to reduce the time and effort involved in the preparation process, a compact, self-contained polishing unit has been developed. This system is based upon the conventional two-stage electropolishing technique in which the specimen/tip blank is first locally thinned or “necked”, and subsequently electropolished until separation occurs.[2,3] The result of this process is the production of two APFIM or STM tips. A mechanized polishing unit that provides these functions while automatically maintaining alignment has been designed and developed.

Simulations of high-resolution images of amorphous silicon films

1986 ◽  
Vol 44 ◽  
pp. 544-545
Author(s):  
G. Y. Fan ◽  
J. M. Cowley
Keyword(s):  
Electron Microscope ◽  
High Frequency ◽  
Fourier Transformation ◽  
Amorphous Materials ◽  
Low Frequency ◽  
Chromatic Aberration ◽  
Structure Information ◽  
Frequency Components ◽  
High Resolution Images ◽  
Spatial Frequency Spectrum

It is well known that the structure information on the specimen is not always faithfully transferred through the electron microscope. Firstly, the spatial frequency spectrum is modulated by the transfer function (TF) at the focal plane. Secondly, the spectrum suffers high frequency cut-off by the aperture (or effectively damping terms such as chromatic aberration). While these do not have essential effect on imaging crystal periodicity as long as the low order Bragg spots are inside the aperture, although the contrast may be reversed, they may change the appearance of images of amorphous materials completely. Because the spectrum of amorphous materials is continuous, modulation of it emphasizes some components while weakening others. Especially the cut-off of high frequency components, which contribute to amorphous image just as strongly as low frequency components can have a fundamental effect. This can be illustrated through computer simulation. Imaging of a whitenoise object with an electron microscope without TF limitation gives Fig. 1a, which is obtained by Fourier transformation of a constant amplitude combined with random phases generated by computer.

Sign in / Sign up

Export Citation Format

Share Document