The b value spectrum and η value by the moment method

The earthquake size distribution is generally considered to obey the Gutenberg Richter (GR) law. We have introduced the concept of the b value spectrum based on the moment method to investigate the deviation of the actual magnitude distribution of earthquakes from this law. This enables us to describe characteristic features of the magnitude frequency distribution of earthquakes. We found also a simple relation between the η value and the b value spectrum. Analysis using this scheme showed that the actual size distributions of earthquakes have large variations from case to case and sometimes deviate considerably from the widely assumed the GR formula.

Estimation of dynamic stress spectrum distribution in structural fatigue test

The determination of structural dynamic stress spectrum distribution is of great signifi- cance in the structural fatigue strength evaluation as well as reliability design. In previous empirical data processing methods, the data grouping and distribution fitting were excessively coarse and contained distinctive defects. This paper proposed an effective approach to statistically group actual measured dynamic stress data and validly extrapolate the combined distribution to fit the dynamic stress spectrum distribution. This approach has been verified its effectiveness through chi-square test, stress spectrum extrapolation and damage calculation in dynamic stress study.

Rapid diagnostic method for transplutonium isotope production in high flux reactors

Transplutonium isotopes are scarce and need to be produced by irradiation in high flux reactors.However,their production is inefficient,and optimization studies are necessary.This study analyzes the physical nature of transplutonium isotope produc-tion using ^(252)Cf,^(244)Cm,^(242)Cm,and ^(238)Pu as examples.Traditional methods based on the Monte Carlo burnup calculation have the limitations of many calculations and cannot analyze the individual energy intervals in detail;thus,they cannot sup-port the refined evaluation,screening,and optimization of the irradiation schemes.After understanding the physical nature and simplifying the complexity of the production process,we propose a rapid diagnostic method for evaluating radiation schemes based on the concepts“single energy interval value(SEIV)”and“energy spectrum total value(ESTV)”.The rapid diagnostic method not only avoids tedious burnup calculations,but also provides a direction for optimization.The optimal irradiation schemes for producing ^(252)Cf,^(244)Cm,^(242)Cm,and ^(238)Pu are determined based on a rapid diagnostic method.Optimal irradiation schemes can significantly improve production efficiency.Compared with the initial scheme,the optimal scheme improved the production efficiency of ^(238)Pu by 7.41 times;^(242)Cm,11.98 times;^(244)Cm,65.20 times;and ^(252)Cf,15.08 times.Thus,a refined analysis of transplutonium isotope production is conducted and provides a theoretical basis for improving production efficiency.

PREDICTIVE STUDY ON THE ECONOMIC VALUE OF RADIO SPECTRUM IN CHINA

Increasing popularity of spectrum-based services brings the striking contradictions between the limited spectrum resource and its increasing demands.This paper puts forward an approach to forecast the future spectrum demand and its economic value,so as to offer a scientific basis for spectrum regulators to resolve this contradiction effectively and make a long-term spectrum-use plan.Specifically,this paper analyzes the driving factors of spectrum demand firstly,based on which a forecasting model is constructed to predict the spectrum demand and its deficit/surplus in the next few years.Then,a forecasting model to measure the economic value of spectrum is proposed based on marginal opportunity cost theory,and the indifference curve is introduced to show the economic value generated by additional spectrum.Additionally,an empirical study is conducted to forecast the spectrum demand and its economic value for China in the next 10 years according to the proposed method.The results of this study show that spectrum deficit is a trend in future and releasing additional spectrum will bring China huge economic benefits.

Spectral Representation of Proton NMR Spectroscopy for the Pattern Recognition of Complex Materials

Proton nuclear magnetic resonance(NMR)spectroscopy provides a powerful tool for chemical profiling,also known as spectral fingerprinting,because of its inherent reproducibility.NMR is now increasing in use for authentication of complex materials.Typically,the absorbance spectrum is used that is obtained as the phase-corrected real component of the Fourier transform(FT)of the free induction decay(FID).However,the practice discards half the information that is available in the dispersion spectrum obtained as the imaginary component from the FT.For qualitative analysis or quantitative analysis of small sets of absorbance peaks,the symmetric and sharp peaks of the real spectra work well.However,for pattern recognition of entire spectra,trading peak resolution for peak reproducibility is beneficial.The absolute value of the complex spectrum gives the length or magnitude of magnetization vector in the complex plane;therefore,the magnitude relates directly to the signal(i.e.,induced magnetization).The magnitude spectrum is obtained as the absolute value from the real and imaginary spectral components after the FT of the FID.By breaking with tradition and using the magnitude spectrum the reproducibility of the spectra and consequent recognition rates can be improved.This study used a 500-MHz 1H NMR instrument to obtain spectra from 4 diverse datasets;12 tea extracts,8 liquor samples,9 hops extracts,and 25 Cannabis extracts.Six classifiers were statistically evaluated using 100 bootstrapped Latin partitions.The classifiers were a fuzzy rule-building expert system(FuRES)tree,support vector machine trees(SVMTreeG and SVMTreeH),a regularized linear discriminant analysis(LDA),super partial least squares discriminant analysis(sPLS-DA),and a one against all support vector machine(SVM).All classifiers gave better or equivalent results for the magnitude spectral representation than for the real spectra,except for one case of the 24 evaluations.In addition,the enhanced reproducibility of the absolute value spectra is demonstrated by comparisons of the pooled within sample standard deviations.For pattern recognition of NMR spectra,the magnitude spectrum is advocated.