Magnitude Interval Research Articles

Determination of the Spatial Distribution Function of Bohai Seismic Tectonic Area

The spatial distribution function assigns seismicity parameters of seismic zone and belt to the potential earthquake source area seismic by the magnitude interval, determination of the spatial distribution function is one of the key technologies to comprehensive probabilistic seismic hazard analysis methods, and the results will directly influence seismic hazard analysis results of the calculated sites. However, the spatial distribution functions are hard to get by statistics due to serious lack of seismic samples, and evaluation factors used in the actual work are too complex and not independent, the spatial distribution function is lack of reliability. In this paper, Bohai seismic tectonic area is chosen as an example; geological data are obtained from the newly built offshore oil platform engineering in recent decades, while seismic activity data are obtained by checking from historical difficult seismic parameters. Five factors are adopted in this area, including potential seismic focus area, seismic tectonic, seismic activity level, long-term forecasts, and strong earthquake recurrence interval and construct empty segment. Spatial distribution function of Bohai Sea earthquake structure area is obtained by weighted comprehension; it reflects the spatial and temporal heterogeneity of seismic activities in the area, and provides the calculation parameters for the probabilistic seismic hazard analysis.

The dynamics of the epileptic brain reveal long-memory processes.

The pattern of epileptic seizures is often considered unpredictable and the interval between events without correlation. A number of studies have examined the possibility that seizure activity respects a power-law relationship, both in terms of event magnitude and inter-event intervals. Such relationships are found in a variety of natural and man-made systems, such as earthquakes or Internet traffic, and describe the relationship between the magnitude of an event and the number of events. We postulated that human inter-seizure intervals would follow a power-law relationship, and furthermore that evidence for the existence of a long-memory process could be established in this relationship. We performed a post hoc analysis, studying eight patients who had long-term (up to 2 years) ambulatory intracranial EEG data recorded as part of the assessment of a novel seizure prediction device. We demonstrated that a power-law relationship could be established in these patients (β = − 1.5). In five out of the six subjects whose data were sufficiently stationary for analysis, we found evidence of long memory between epileptic events. This memory spans time scales from 30 min to 40 days. The estimated Hurst exponents range from 0.51 to 0.77 ± 0.01. This finding may provide evidence of phase-transitions underlying the dynamics of epilepsy.

Cost of capital estimation for energy efficiency projects through a cash flow beta approach

This paper presents a methodological framework for project beta estimation according to the Capital Asset Pricing Model (CAPM) when relevant stock price data are not available but cash flow data are. The methodology suggests estimating a cash flow beta first, which can then be converted into the traditional stock beta of a project. Estimation of the cash flow beta requires a series of past expectations regarding the project’s cash flows. We generate these expectations from time-series models describing the cash flow process. In the case of energy efficiency projects, we argue that it is sufficient to consider only the energy price uncertainty in the cash flows. Analyzing monthly residential retail price data for electricity, natural gas, and heating oil in the USA, we find that the use of price changes, as applied by related studies, is inappropriate for beta estimation and that it may lead to errors in magnitude, incorrect signs, and wider confidence intervals for beta estimates because none of these prices are martingales. After adjusting for this issue, we find very small betas. Moreover, considering their possible range, we conclude that the risk-free rate is generally a good approximation for energy efficiency projects.

THE ALGORITHM OF SUPPLEMENTARY ARGUMENTS INCLUSION FOR INTERVAL MODELS STRUCTURAL IDENTIFICATION OF THE STATIC SYSTEMS

The problem of structural identification of static models of interval systems. Showing getting a unique solution for the problem of structural identification for different initial given structure models based on the complexity of the proposed algorithm sequential structures. An adaptive iterative procedure, which reduces the dependence of the result of structural identification of the magnitude interval error data.

Stress Drops of the 1997–1998 Colfiorito, Central Italy Earthquakes: Hints for a Common Behaviour of Normal Faults in the Apennines

Stress drop estimates of moderate-magnitude earthquakes in the Umbria–Marche region, in the northern Apennines, exhibit a large scatter. For the two Mw 5.7 and 6.0 main shocks of 26 September 1997 near Colfiorito, several papers resulted in stress drop estimates of 20 MPa, but values as low as 2–3 MPa were proposed as well. Also for the largest aftershocks (Mw > 4), estimates spread from < 1 MPa up to values ten times larger. We have critically revisited methods and data used in the literature. We have specifically faced the trade-off between source and propagation effects, as we believe that it is responsible for a part of the large scatter. To keep this trade-off under control, we have applied a methodology that combines the best fit of both source spectra after Empirical Green’s Function (EGF) deconvolution and observed ground motion spectra, finding that the results of the two different data sets converge independently at the same solution. We have used ground motions observed in the Colfiorito basin, where an accelerograph and a co-located seismological broad-band station recorded three clusters of earthquakes in a broad magnitude interval (1.7 ≤ Mw ≤ 6.0). We have found that the mainshock–aftershock sequences result in stress drops of 2–5 MPa at Mw ≥ 5.6, with an average tendency to decrease at smaller magnitudes where stress drop variability increases. These findings confirm the source scaling recently assessed through Empirical Green’s Function deconvolution for another well-monitored seismic sequence of normal-faulting earthquakes, which struck the city of L’Aquila in the central Apennines in April 2009. The similar scaling law of the two areas suggests common mechanisms of stress release for the shallow normal faults in the Apennines. The propensity of smaller earthquakes to increase in variability, with a tendency toward smaller stress drops, may reflect an effect of fault strength heterogeneities for smaller size ruptures.

Estimation of absolute magnitude-dependent Galactic model parameters in intermediate latitude with SDSS and SCUSS

Based on the Sloan Digital Sky Survey and South Galactic Cap of u-band Sky Survey (SCUSS) early data, we use a star count method to estimate the Galactic structure parameters in an intermediate latitude with 10 180 main-sequence (MS) stars in an absolute magnitude interval of 4 ≤ Mr ≤ 13. We divide the absolute magnitude into five intervals, 4 ≤ Mr < 5, 5 ≤ Mr < 6, 6 ≤ Mr < 8, 8 ≤ Mr < 10 and 10 ≤ Mr ≤ 13, and estimate the Galactic structure parameters in each absolute magnitude interval to explore their possible variation with the absolute magnitude. Our study shows that the parameters depend on absolute magnitude. For the thin disc, the intrinsic faint MS stars have large local space density and they tend to stay close to the Galactic plane. A plausible explanation is that faint MS stars with long lifetime experience and long gravitational interaction time result in a short scaleheight. However, for the thick disc, the parameters show a complex trend with absolute magnitude, which may imply the complicated original of the thick disc. For the halo, the intrinsic faint MS stars have large local density and small axial ratio, which indicate a flattened inner halo and a more spherical outer halo.

Characterisation of the Quaternary eruption record: analysis of the Large Magnitude Explosive Volcanic Eruptions (LaMEVE) database

The Large Magnitude Explosive Volcanic Eruptions (LaMEVE) database contains data on 1,883 Quaternary eruption records of magnitude (M) 4 and above and is publically accessible online via the British Geological Survey. Spatial and temporal analysis of the data indicates that the record is incomplete and is thus biased. The recorded distribution of volcanoes is variable on a global scale, with three-quarters of all volcanoes with M≥4 Quaternary activity located in the northern hemisphere and a quarter within Japan alone. The distribution of recorded eruptions does not strictly follow the spatial distribution of volcanoes and has distinct intra-regional variability, with about 40% of all recorded eruptions having occurred in Japan, reflecting in part the country’s efforts devoted to comprehensive volcanic studies. The number of eruptions in LaMEVE decreases with increasing age, exemplified by the recording of 50% of all known Quaternary eruptions during the last 20,000 years. Historical dating is prevalent from 1450 AD to the present day, substantially improving record completeness. The completeness of the record also improves as magnitude increases. This is demonstrated by the calculation of the median time, T50, for eruptions within given magnitude intervals, where 50% of eruptions are older than T50: T50 ranges from 5,070 years for M4-4.9 eruptions to 935,000 years for M≥8 eruptions. T50 follows a power law fit, suggesting a quantifiable relationship between eruption size and preservation potential of eruptive products. Several geographic regions have T50 ages of <250 years for the smallest (~M4) eruptions reflecting substantial levels of under-recording. There is evidence for latitudinal variation in eruptive activity, possibly due to the effects of glaciation. A peak in recorded activity is identified at 11 to 9 ka in high-latitude glaciated regions. This is absent in non-glaciated regions, supporting the hypothesis of increased volcanism due to ice unloading around this time. Record completeness and consequent interpretation of record limitations are important in understanding volcanism on global to local scales and must be considered during rigorous volcanic hazard and risk assessments. The study also indicates that there need to be improvements in the quality of data, including assessment of uncertainties in volume estimates.

The debate on the prognostic value of earthquake foreshocks: A meta-analysis

The hypothesis that earthquake foreshocks have a prognostic value is challenged by simulations of the normal behaviour of seismicity, where no distinction between foreshocks, mainshocks and aftershocks can be made. In the former view, foreshocks are passive tracers of a tectonic preparatory process that yields the mainshock (i.e., loading by aseismic slip) while in the latter, a foreshock is any earthquake that triggers a larger one. Although both processes can coexist, earthquake prediction is plausible in the first case while virtually impossible in the second. Here I present a meta-analysis of 37 foreshock studies published between 1982 and 2013 to show that the justification of one hypothesis or the other depends on the selected magnitude interval between minimum foreshock magnitude mmin and mainshock magnitude M. From this literature survey, anomalous foreshocks are found to emerge when mmin < M − 3.0. These results suggest that a deviation from the normal behaviour of seismicity may be observed only when microseismicity is considered. These results are to be taken with caution since the 37 studies do not all show the same level of reliability. These observations should nonetheless encourage new research in earthquake predictability with focus on the potential role of microseismicity.

Modified probabilistic approach for seismic hazard zoning of Golestan region, Iran

In this article, seismic zoning maps of Golestan based on modified methodology of probabilistic seismic hazard analysis have been prepared. For this purpose, first, major seismotectonic provinces of Iran surrounding the study region are delineated and seismicity parameters are evaluated for each province. By determining the main active faults of the region and preparing the earthquake catalog containing 19 historical events and 270 instrumental events, 25 potential seismic sources are modelled as area sources in the region. In order to properly reflect the inhomogeneity of seismicity in time and space, and to avoid underestimation of potential hazard of large magnitude earthquakes, the annual mean occurrence rate of earthquakes in each seismotectonic province should be allocated to each magnitude interval in the corresponding potential seismic sources, using the spatial distribution function. In this research, different kinds of seismological, tectonic and geophysical data are used to indicate the possible future earthquake activities in the interest region, providing basis for evaluation of spatial distribution function. Seismic hazard assessment is carried out by considering a universal attenuation relationship and using the SEISRISKIII computer program for the area in a radius of 200 km from centre of Gorgan (the centre of Golestan province). The study region is divided into a series of grid points and seismic hazard analysis for every grid point is carried out using characteristics of seismic activity in seismotectonic provinces and potential seismic sources. Horizontal Peak Ground Acceleration (PGA) for different seismic hazard levels is evaluated by modified probabilistic estimation. Finally, seismic hazard zoning maps of Golestan for 10% Probability of exceedance (PE) and 2% PE in 50 years and for three types of the site soil are prepared and compared with the seismic hazard macrozonation of Iran based on standard 2800.

Analysis of Electromagnetic Force Distribution on End Winding of Electrical Submersible Motor During Starting Transient Operation

Generally, an electrical submersible motor generates a current with high magnitude and long interval during starting transient operation. This paper aims to analyze the electromagnetic forces on the stator end windings of an electrical submersible motor during the starting transient operation by a 3-D finite element method (FEM). A 3-D model was conducted and some complex support structures in the end regions were simplified. Then we analyzed the electromagnetic field in the end region according to the governing equations and the boundary conditions. The analysis shows that the forces on the outer layer especially in 1st and 5th coil are larger than those on the other parts. Furthermore, the force distributions on the coils in the same phase belt are different and the force distribution in each segment varies with the position and the direction. Finally, the analysis of stresses indicates that the stresses in a coil end are not small but within the yield strength of the copper coils.

Diurnal periodicity of the representative earthquakes in Greece

The diurnal periodicity of seismic events of different energy from the Greece earthquake catalog was studied. Earthquake samplings of different energy with a known level of magnitude of completeness were compiled. Parameters of the diurnal periodicity of earthquakes in different time and magnitude intervals were analyzed. Significant diurnal periodicity of earthquakes with M ≤ 4.1 was revealed. The most important result of the paper is the discovery of the diurnal periodicity of the representative earthquakes with M = 3.2–4.1. The diurnal periodicity of representative earthquakes cannot be explained at the base of the prevailing hypothesis considering the diurnal periodicity of earthquakes as an apparent phenomenon resulting from diurnal changes in the real sensitivity of the seismic network due to diurnal variations of seismic noise.

Nonextensive triplet in a geological faults system

The San Andreas fault (SAF) in the USA is one of the most investigated self-organizing systems in Nature. In this paper, we studied some geophysical properties of the SAF system in order to analyze the behavior of earthquakes in the context of Tsallis's q-Triplet. To this end, we considered 134573 earthquake events in the magnitude interval , taken from the Southern Earthquake Data Center (SCEDC, 1932–2012). The values obtained (“q-Triplet”) reveal that the -Gaussian behavior of the aforementioned data exhibit long-range temporal correlations. Moreover, exhibits quasi-monofractal behavior with a Hurst exponent of 0.87.

Aperture corrections for disk galaxy properties derived from the CALIFA survey

This work investigates the effect of the aperture size on derived galaxy properties for which we have spatially-resolved optical spectra. We focus on some indicators of star formation activity and dust attenuation for spiral galaxies that have been widely used in previous work on galaxy evolution. We have used 104 spiral galaxies from the CALIFA survey for which 2D spectroscopy with complete spatial coverage is available. From the 3D cubes we have derived growth curves of the most conspicuous Balmer emission lines (Halpha, Hbeta) for circular apertures of different radii centered at the galaxy's nucleus after removing the underlying stellar continuum. We find that the Halpha flux (f(Halpha)) growth curve follows a well defined sequence with aperture radius showing low dispersion around the median value. From this analysis, we derive aperture corrections for galaxies in different magnitude and redshift intervals. Once stellar absorption is properly accounted for, the f(Halpha)/f(Hbeta) ratio growth curve shows a smooth decline, pointing towards the absence of differential dust attenuation as a function of radius. Aperture corrections as a function of the radius are provided in the interval [0.3,2.5]R_50. Finally, the Halpha equivalent width (EW(Halpha)) growth curve increases with the size of the aperture and shows a very large dispersion for small apertures. This large dispersion prevents the use of reliable aperture corrections for this quantity. In addition, this result suggests that separating star-forming and quiescent galaxies based on observed EW(Halpha) through small apertures is likely to result in low EW(Halpha) star-forming galaxies begin classified as quiescent.

Numerical quantity affects time estimation in the suprasecond range

Of stimuli differing in the magnitude of their numerical information, the one with the larger numerosity is perceived to last longer than that with the smaller numerosity. This numerosity–time interaction is proposed to be due to a shared neural representation for numerical magnitude and time intervals in the parietal cortex. Neuroimaging studies of temporal processing suggest that subsecond and suprasecond intervals could be mediated by distinct neural substrates. However, whether the numerosity–time interaction occurs independently of the time intervals used in the tasks remains unknown. Here we show that numerical information interacts with time estimation in the suprasecond range in females, but not in males. Our results suggest that the numerical magnitude and suprasecond intervals have shared representations in the human brain, but the associative strength between these dimensions might be different between males and females.

Earthquake prediction in seismogenic areas of the Iberian Peninsula based on computational intelligence

A method to predict earthquakes in two of the seismogenic areas of the Iberian Peninsula, based on Artificial Neural Networks (ANNs), is presented in this paper. ANNs have been widely used in many fields but only very few and very recent studies have been conducted on earthquake prediction. Two kinds of predictions are provided in this study: a) the probability of an earthquake, of magnitude equal or larger than a preset threshold magnitude, within the next 7days, to happen; b) the probability of an earthquake of a limited magnitude interval to happen, during the next 7days. First, the physical fundamentals related to earthquake occurrence are explained. Second, the mathematical model underlying ANNs is explained and the configuration chosen is justified. Then, the ANNs have been trained in both areas: The Alborán Sea and the Western Azores–Gibraltar fault. Later, the ANNs have been tested in both areas for a period of time immediately subsequent to the training period. Statistical tests are provided showing meaningful results. Finally, ANNs were compared to other well known classifiers showing quantitatively and qualitatively better results. The authors expect that the results obtained will encourage researchers to conduct further research on this topic.

토크예측제어를 이용한 매입형 영구자석 동기전동기의 토크리플저감기법

In this paper, a new torque predictive control method of interior permanent magnet synchronous motor is developed based on an extended rotor flux. Also, a duty ratio prediction method is proposed and allows the duty ratio of the active stator voltage vector to be continuously calculated. The proposed method makes it possible to relatively reduce the torque ripple under the steady state as well as to remain the good dynamic response in the transient state. With the duty ratio prediction method, the magnitude and time interval of the active stator voltage vector applied can be continuously controlled against the varying operation conditions. This paper shows a comparative study among the switching table direct torque control(DTC), the SVM-DTC, conventional torque predictive control, and the proposed torque predictive control. Simulation results show validity and effectiveness of this work.

Testing Prediction Performance of Poverty Models: Empirical Evidence from Uganda

This paper examines the performance of a method of predicting poverty rates. Because most developing countries cannot justify the expense of frequent household budget surveys, additional low‐cost methods have been developed and used. The prediction method is based on a model linking the proportion of poor households to suitable explanatory variables (consumption proxies). These consumption proxies are variables that can be collected at much lower cost through smaller annual surveys. Several applications have shown that such models can produce poverty estimates with confidence intervals of a similar magnitude to the poverty estimates from the household budget surveys. There is, however, limited evidence of how well the methods perform out‐of‐sample. A series of seven household budget surveys conducted in Uganda in the period 1993–2005 allows us to test the prediction performance of the model. We test the poverty models by using data from one survey to predict the proportion of poor households in other surveys, and vice versa. The results are encouraging, as all models predict similar poverty trends. Although in most cases the predictions are precise, sometimes they differ significantly from the poverty level estimated from the survey directly.

Discriminative validity of the Scoliosis Research Society 22 questionnaire among five curve-severity subgroups of adolescents with idiopathic scoliosis

Background contextPrevious studies of the Scoliosis Research Society (SRS) 22 discriminative validity have lacked sufficiently matched study groups and were limited to a comparison with three or fewer subgroups of disease severity. PurposeTo evaluate the discriminative validity of SRS-22 by assessing the questionnaire's ability to discriminate among five groups of pretreatment adolescent idiopathic scoliosis (AIS) patients with increasing curve severity. Study designRetrospective review of prospectively administered surveys. MethodsTwo hundred eighty-six SRS-22 questionnaires were issued to two AIS pretreatment patient populations: 67 nonoperative and 219 preoperative. Study subjects were separated into five subgroups depending on the major Cobb angle (nonoperative 0°–19° and 20°–40° and preoperative 41°–50°, 51°–60°, and >60°). Each group (n=31) was matched for age (within 1 year) and sex (23 females and 8 males), resulting in a total of 155 study subjects. Analysis of variance was used to determine statistically significant differences (p<.05) between the five subgroups' domains and total scores. ResultsSignificant differences between study groups were found within two of the four domains (pain and image) and the total score. Both nonoperative groups (0°–19° and 20°–40°) demonstrated significantly less pain than the preoperative group (41°–50°) and significantly better self-image than all three preoperative groups. Both nonoperative groups' total scores were significantly higher than all three preoperative groups' scores, with the exception of the 20° to 40° subgroup versus the >60° subgroup. No significant differences were found between groups within the same planned treatment category. ConclusionsThe SRS-22 questionnaire demonstrated good discriminative validity between small nonoperative curves and larger surgical curves within the pain, image, and total domains. However, SRS-22 lacked the ability to differentiate between small intervals of curve magnitude, suggesting a limitation to the questionnaire's discriminative capacity. The discriminative validity of the Scoliosis Research Society (SRS) 22 has not been clearly defined. Our analysis of 155 adolescent idiopathic scoliosis patients evaluates the instrument's discriminative validity among five age- and sex-matched curve-severity subgroups. The SRS-22 questionnaire lacked the ability to differentiate between small intervals of curve magnitude, suggesting a limit to the questionnaire's discriminative capacity.

Neural networks to predict earthquakes in Chile

A new earthquake prediction system is presented in this work. This method, based on the application of artificial neural networks, has been used to predict earthquakes in Chile, one of the countries with larger seismic activity. The input values are related to the b-value, the Bath's law, and the Omori–Utsu's law, parameters that are strongly correlated with seismicity, as shown in solid previous works. Two kind of prediction are provided in this study: The probability that an earthquake of magnitude larger than a threshold value happens, and the probability that an earthquake of a limited magnitude interval might occur, both during the next five days in the areas analyzed. For the four Chile's seismic regions examined, with epicenters placed on meshes with dimensions varying from 0.5°×0.5° to 1°×1°, a prototype of neuronal network is presented. The prototypes predict an earthquake every time the probability of an earthquake of magnitude larger than a threshold is sufficiently high. The threshold values have been adjusted with the aim of obtaining as few false positives as possible. The accuracy of the method has been assessed in retrospective experiments by means of statistical tests and compared with well-known machine learning classifiers. The high success rate achieved supports the suitability of applying soft computing in this field and poses new challenges to be addressed.

Characterization of surface discharge as indicator for hydrophobicity evaluation of silicone rubber insulators

A Dynamic drop test (DDT) has been employed for hydrophobicity evaluation, which has proven the occurrence of different discharge phenomena in relation to the hydrophobicity variation. In this paper, based on DDT method, the characterization of surface discharges, including the discharge magnitude, pulse number, adjacent discharge magnitude and adjacent time interval, have been analyzed to evaluate the surface hydrophobicity of silicone rubber insulator. It is found that with the decrease of hydrophobicity, these characteristics apparently show an increasing tendency. The characteristic pattern of discharge pulse and discharge magnitude presents a twin-peak shape, in which both the increase of the discharge magnitude and the discharge pulse number of higher magnitude reflect the decrease of surface hydrophobicity. The characteristic pattern of adjacent discharge magnitude and discharge magnitude emerges to be an 'X' shape composed by the discharge spots, in which the larger value in both the spot density and the shape expansion reveals the decreasing hydrophobicity. The characteristic pattern of next time interval and discharge magnitude demonstrates the frequency of surface discharges increases with the decrease of surface hydrophobicity. Furthermore, the comparability between the discharge characteristic methods and the contact angle method is analyzed to obtain the higher similarity coefficients. Obtained results indicate that the characteristic of surface discharge in DDT method can be utilized to the hydrophobicity evaluation.