Near earthquakes in Central California*

1939 ◽  
Vol 29 (3) ◽  
pp. 427-462 ◽  
Author(s):  
Perry Byerly
Keyword(s):  
Least Squares ◽  
Travel Time ◽  
Sierra Nevada ◽  
Accurate Determination ◽  
Depth Of Focus ◽  
Surface Layers ◽  
P Waves ◽  
Central California ◽  
The Waves

Summary Least-squares adjustments of observations of waves of the P groups at central and southern California stations are used to obtain the speeds of various waves. Only observations made to tenths of a second are used. It is assumed that the waves have a common velocity for all earthquakes. But the time intercepts of the travel-time curves are allowed to be different for different shocks. The speed of P̄ is found to be 5.61 km/sec.±0.05. The speed for S̄ (founded on fewer data) is 3.26 km/sec. ± 0.09. There are slight differences in the epicenters located by the use of P̄ and S̄ which may or may not be significant. It is suggested that P̄ and S̄ may be released from different foci. The speed of Pn, the wave in the top of the mantle, is 8.02 km/sec. ± 0.05. Intermediate P waves of speeds 6.72 km/sec. ± 0.02 and 7.24 km/sec. ± 0.04 are observed. Only the former has a time intercept which allows a consistent computation of structure when considered a layer wave. For the Berkeley earthquake of March 8, 1937, the accurate determination of depth of focus was possible. This enabled a determination of layering of the earth's crust. The result was about 9 km. of granite over 23 km. of a medium of speed 6.72 km/sec. Underneath these two layers is the mantle of speed 8.02 km/sec. The data from other shocks centering south of Berkeley would not fit this structure, but an assumption of the thickening of the granite southerly brought all into agreement. The earthquakes discussed show a lag of Pn as it passes under the Sierra Nevada. This has been observed before. A reconsideration of the Pn data of the Nevada earthquake of December 20, 1932, together with the data mentioned above, leads to the conclusion that the root of the mountain mass projects into the mantle beneath the surface layers by an amount between 6 and 41 km.

scholarly journals Rapid and accurate determination of tissue optical properties using least-squares support vector machines

2011 ◽  
Vol 2 (3) ◽  
pp. 592 ◽  
Author(s):  
Ishan Barman ◽  
Narahara Chari Dingari ◽  
Narasimhan Rajaram ◽  
James W. Tunnell ◽  
Ramachandra R. Dasari ◽  
...  
Keyword(s):  
Optical Properties ◽  
Support Vector Machines ◽  
Least Squares ◽  
Accurate Determination ◽  
Support Vector ◽  
Tissue Optical Properties ◽  
Vector Machines

scholarly journals Experimental investigations of very long waves reflected from the ionosphere

1936 ◽  
Vol 156 (889) ◽  
pp. 614-633 ◽  
Keyword(s):  
Interference Pattern ◽  
Accurate Determination ◽  
Long Waves ◽  
Experimental Investigations ◽  
Great Length ◽  
Interference System ◽  
Phase Variations ◽  
Characteristic Features ◽  
The Waves

This paper is an account of experiments which have been carried out to determine the characteristic features (amplitude, height of reflexion, and polarization) of waves of very great length (18·8 km) reflected from the ionosphere at fairly small angles of incidence. The transmission characteristics of long waves have previously been studied by Holling-worth, Naismith, and Namba. In Hollingworth's pioneer experiment measurement were made on the space characteristics of the interference pattern produced at the ground by the superposition of the direct and the downcoming wave. the observations were made within the range 300-1000 bin from the sender, during the daytime, and one minimum and one maximum of the interference pattern were located. With the large distances to be covered the measurements extended over three months, and it was necessary to assume constancy of the conditions from day to day. The result demonstrate the presence of the interference system in a very beautiful manner, but cannot be used for an accurate determination of the height of reflexion at any one time. In §2 of the present paper we describe experiments, of the same type as Holling-worth's, carried out at shorter distances (70-140 km). The advantage of using shorter transmission distances are twofold. Firstly, it is possible to make sufficient measurements in the course of a single day (or night) to determine the reflexion height and the reflexion coefficient for a single day (or night), and, secondly, the information derived applies to the conditions of nearly vertical incidence, and so is more directly comparable with the detailed information which is now available concerning short waves. In the papers mentioned above muck attention has been given to the observation and explanation of the effects observed near sunset. It is pointed out that if the resultant signal strength on a single aerial system is alone observed, it is impossible to decide whether the changes are due to changes of amplitude, phase, or polarization of the downcoming wave. Assuming that the sunset variations are due entirely to phase variations, Hollingworth first deduced a change of reflexion height from 75 km to 90 km during sunset, but later believed that the variations were almost entirely explained by a rotation of the plane of polarization of the wave, and that the change of reflexion height was only about 2 km. Naismith states that no sunset variations are observable at short distances (100 km) from the sender, and suggests that at vertical incidence the waves are reflected from a higher level which does not exhibit changes at sunset.

The amplitude ratio, PP/P, as recorded by Galitzin seismographs*

1943 ◽  
Vol 33 (3) ◽  
pp. 149-195
Author(s):  
Alexis I. Mei
Keyword(s):  
Amplitude Ratio ◽  
Angle Of Incidence ◽  
Surface Layers ◽  
P Waves ◽  
Direct Wave ◽  
Longitudinal Waves ◽  
The Earth ◽  
The Pacific ◽  
The Pacific Ocean ◽  
The Waves

Abstract The ratio of the amplitude of the longitudinal wave reflected at the surface of the earth to that of the direct wave as recorded by Galitzin seismographs was examined to find whether it might be used as a means of distinguishing between Pacific and continental reflections. Theoretically, assuming that equal energy is radiated in all directions from the source, the amplitude ratio, PP/P, for Pacific reflections should be smaller than for continental reflections at all epicentral distances, if the speed of P waves near the surface is higher under the Pacific than under the continents. The records of 194 earthquakes with epicenters at distances from 19° to 103°, and having reflections under the continents or the Pacific Ocean, were examined for the purpose. No such pattern as expected by theory was observed; on the contrary there resulted a general scattering when these ratios were plotted, for both types of reflection, against epicentral distances. The observed values of the apparent angle of incidence agreed better with those calculated for V = 8.00 km/sec. than with those for V = 6.00 km/sec., where V is the velocity of P waves near the surface of the earth. Since 8.00 km/sec. is the velocity of longitudinal waves below the surface layers of the continents, while 6.00 km/sec. is an intermediate velocity within the layers, it was concluded that the waves recorded by the Galitzin seismographs were not refracted into the surface layers of the earth and consequently that the amplitudes of waves of the periods recorded on Galitzin seismographs (4 sec. to 12 sec.) do not afford a means of differentiating between reflections at a layered surface such as the continent and at an unlayered surface such as Gutenberg considers the Pacific to be. However, comparison of some twenty records of the vertical Benioff seismograph of approximately 0.7 sec. free period (recorded waves of periods 1 sec. to 2 sec.) with those of the same earthquakes recorded by the Galitzins of 12 sec. free period showed no essentially different behavior. It was observed that the Berkeley, California, and Florissant, Missouri, stations, both using Galitzin instruments of nearly the same constants, were situated at the same distances from eight Mexican epicenters, and both received impulses from these earthquakes over the same kind of continental paths. An examination of their respective values of PP/P showed this to be larger at one station or another according as the first recorded motion at Berkeley was a condensation or a rarefaction. This variation in the values of PP/P shows that energy is not sent out equally in all directions from the source, as was assumed, and therefore that the mechanism at the focus plays an important part in the value of this ratio.

The Central California earthquakes of May 16, 1933, and June 7, 1934

1935 ◽  
Vol 25 (3) ◽  
pp. 223-246 ◽  
Author(s):  
Perry Byerly ◽  
James T. Wilson
Keyword(s):  
Travel Time ◽  
Earth’S Crust ◽  
Coast Range ◽  
Owens Valley ◽  
P Waves ◽  
Central California ◽  
Earth's Crust ◽  
Great Valley

Abstract Isoseismalsare drawn and field intensities listed for the Niles earthquake of May 16, 1933. The epicenter is placed at 37° 38′ N, 121° 57′ W. Isoseismals are drawn and field intensities listed for the Parkfield earthquakes of June 7, 1934. The epicenter of the shock at 8h 48mp.m. (P.S.T.) is placed at 35° 56′ N, 120° 29′ W. The epicenter of the shock at 8h 30m is placed about 4 km. north of this. Travel-time curves are drawn for each of these three shocks. It is shown that the Owens Valley stations, Tinemaha and Haiwee, did not record the normal P (v = 8.0 km/sec., ca.) for any of these earthquakes. It is concluded that there exists some barrier to these waves under the Great Valley of California (or possibly under the Sierra), which prevents their observation at stations so close to the valley as Tinemaha and Haiwee when the source is in the Coast Range region. The interpretation of the data of difficult, but there is some evidence for identifying P waves traveling through three successive layers of the earth's crust. A tentative computation of this structure is made.

scholarly journals Determination of Total Polysaccharides and Total Flavonoids in Chrysanthemum morifolium Using Near-Infrared Hyperspectral Imaging and Multivariate Analysis

Molecules ◽  
2018 ◽  
Vol 23 (9) ◽  
pp. 2395 ◽  
Author(s):  
Juan He ◽  
Lidan Chen ◽  
Bingquan Chu ◽  
Chu Zhang
Keyword(s):  
Least Squares ◽  
Hyperspectral Imaging ◽  
Near Infrared ◽  
Prediction Models ◽  
Accurate Determination ◽  
Chrysanthemum Morifolium ◽  
Support Vector ◽  
Total Flavonoids ◽  
Total Flavonoids Content

The rapid and nondestructive determination of active compositions in Chrysanthemum morifolium (Hangbaiju) is of great value for producers and consumers. Hyperspectral imaging as a rapid and nondestructive technique was used to determine total polysaccharides and total flavonoids content in Chrysanthemum morifolium. Hyperspectral images of different sizes of Chrysanthemum morifolium flowers were acquired. Pixel-wise spectra within all samples were preprocessed by wavelet transform (WT) followed by standard normal variate (SNV). Partial least squares (PLS) and least squares-support vector machine (LS-SVM) were used to build prediction models using sample average spectra calculated by preprocessed pixel-wise spectra. The LS-SVM model performed better than the PLS models, with the determination of the coefficient of calibration (R2c) and prediction (R2p) being over 0.90 and the residual predictive deviation (RPD) being over 3 for total polysaccharides and total flavonoids content prediction. Prediction maps of total polysaccharides and total flavonoids content in Chrysanthemum morifolium flowers were successfully obtained by LS-SVM models, which exhibited the best performances. The overall results showed that hyperspectral imaging was a promising technique for the rapid and accurate determination of active ingredients in Chrysanthemum morifolium, indicating the great potential to develop an online system for the quality determination of Chrysanthemum morifolium.

scholarly journals Rapid Determination of Wood and Rice Husk Pellets’ Proximate Analysis and Heating Value

Energies ◽  
2020 ◽  
Vol 13 (14) ◽  
pp. 3741
Author(s):  
Xiaodan Liu ◽  
Xuping Feng ◽  
Lingxia Huang ◽  
Yong He
Keyword(s):  
Least Squares ◽  
Rapid Determination ◽  
Accurate Determination ◽  
Calorific Value ◽  
Clean Energy ◽  
Energy Utilization ◽  
Support Vector ◽  
Least Squares Regression ◽  
Quality Indexes

Biomass pellets are a potential renewable and clean energy source. With the advantages of perfect combustion performance and easy storage and transport, biomass pellets have gradually replaced fossil fuels and become widely used. Rapid and accurate determination of biomass pellets’ quality is critical to efficient energy use. Laser-induced breakdown spectroscopy (LIBS) combined with chemometric methods were utilized. The gross calorific value (CV) and ash content (Ash), volatile matter (VM) and fixed carbon (FC) were firstly measured and analyzed. LIBS spectra and their corresponding elements of biomass pellet samples were analyzed. Three quantitative analysis models for quality indexes including partial least-squares regression (PLSR), least squares-support vector machines (LS-SVM), extreme learning machines (ELM) were further built. All models performed well, especially the LS-SVM model which obtained the best determination results, with all R2 values over 0.95. Concurrently, the modeling performance of ash was slightly better than that of the other three quality indexes, which further confirmed the feasibility of using relevant elements to predict biomass quality indexes. The overall results indicated that LIBS coupled with suitable chemometrics could be an alternative promising method to determine quality indexes of biomass pellets and further improve energy utilization by using biomass materials with better quality.

The Hebgen Lake, Montana, earthquake of August 18, 1959: P waves

1962 ◽  
Vol 52 (2) ◽  
pp. 235-271
Author(s):  
Alan Ryall
Keyword(s):  
Travel Time ◽  
Sierra Nevada ◽  
Fault Plane ◽  
Time Curve ◽  
P Waves ◽  
Arrival Times ◽  
The Pacific ◽  
First Motion ◽  
Plane Solution ◽  
The Pacific Ocean

ABSTRACT The instrumental epicenter of the Hebgen Lake earthquake is found to lie within the region of surface faulting. The depth of focus had a maximum value of 25 kilometers. Times of P are studied in detail for epicentral distances less than 13 degrees. The apparent scatter of arrival times from 700 to 1400 kilometers can be explained by variations of the velocity of Pn between the physiographic provinces of the western United States. A comparison of observations for the Hebgen Lake earthquake with published times for blasts in Nevada and Utah indicates that the velocity of Pn in the central and eastern Basin and Range is about 7.5 km/sec, and that the crust in that region thickens toward the east and thins toward the south. A comparison of apparent velocities in northern California, in directions parallel and transverse to the structure, indicates that the crust thins by about 19 kilometers, from the edge of the Sierra Nevada to the Pacific Ocean. A discontinuity is observed in the travel-time curve at a distance of 24–25 degrees. Arrivals of P waves in the range 65–128 degrees fall on two parallel travel-time branches; this multiplicity in the travel-time curve may be related to repeated motion at the source. Travel-times of PKIKP appear to deviate from published curves. The fault-plane solution for the Hebgen Lake earthquake, together with a consideration of the first motion at Bozeman, Montana, indicates a focal mechanism of the dipole, or fault, type. The strike and dip of the instrumental fault plane agree well with observed ruptures at the surface.

A quantitative approach to inner shell losses

1978 ◽  
Vol 36 (1) ◽  
pp. 526-527 ◽  
Author(s):  
R.D. Leapman ◽  
P. Rez ◽  
D.F. Mayers
Keyword(s):  
Energy Transfer ◽  
Cross Section ◽  
Cross Sections ◽  
Accurate Determination ◽  
Background Intensity ◽  
Core Excitation ◽  
Quantitative Basis ◽  
Cross Section Differential ◽  
Bound Electrons

Microanalysis by EELS has been developing rapidly and though the general form of the spectrum is now understood there is a need to put the technique on a more quantitative basis (1,2). Certain aspects important for microanalysis include: (i) accurate determination of the partial cross sections, σx(α,ΔE) for core excitation when scattering lies inside collection angle a and energy range ΔE above the edge, (ii) behavior of the background intensity due to excitation of less strongly bound electrons, necessary for extrapolation beneath the signal of interest, (iii) departures from the simple hydrogenic K-edge seen in L and M losses, effecting σx and complicating microanalysis. Such problems might be approached empirically but here we describe how computation can elucidate the spectrum shape.The inelastic cross section differential with respect to energy transfer E and momentum transfer q for electrons of energy E0 and velocity v can be written as

Fast calibration of CBED patterns for quantitative analysis

1993 ◽  
Vol 51 ◽  
pp. 674-675
Author(s):  
M.A. Gribelyuk ◽  
M. Rühle
Keyword(s):  
Reciprocal Lattice ◽  
Accurate Determination ◽  
Incident Beam ◽  
Crystal Thickness ◽  
Structure Model ◽  
Beam Direction ◽  
Transmitted Beam ◽  
Reciprocal Vector ◽  
On Line

A new method is suggested for the accurate determination of the incident beam direction K, crystal thickness t and the coordinates of the basic reciprocal lattice vectors V1 and V2 (Fig. 1) of the ZOLZ plans in pixels of the digitized 2-D CBED pattern. For a given structure model and some estimated values Vest and Kest of some point O in the CBED pattern a set of line scans AkBk is chosen so that all the scans are located within CBED disks.The points on line scans AkBk are conjugate to those on A0B0 since they are shifted by the reciprocal vector gk with respect to each other. As many conjugate scans are considered as CBED disks fall into the energy filtered region of the experimental pattern. Electron intensities of the transmitted beam I0 and diffracted beams Igk for all points on conjugate scans are found as a function of crystal thickness t on the basis of the full dynamical calculation.

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