A normalized statistical study of Earth’s cusp region based on nine-years of Cluster measurements

Nine years(2001–2009)of data from the Cluster spacecraft are analyzed in this study of the Earth’s mid-and high-altitude(2–9RE)cusp.Properties of the cusp region,and its location and size in the Solar Magnetic coordinate system,are studied statistically.The survey shows that(1)the relationships between X and Z are nearly linear for the poleward,equatorward boundaries and the center of the cusp;(2)the relationship between cusp width in the X direction and Z can be expressed by a quadratic function;(3)the cusp region is almost dawn-dusk symmetric for the cusp width in the X direction.Based on topology information,a new normalized statistical methodology is developed to organize the measurements of cusp crossings to obtain distributions of magnetic field and plasma parameters in the XZ plane.The statistical results show that(1)Bx is mostly negative and Bz is always negative;(2)proton velocity is found to be positive for Vx and Vz at low altitudes,while Vx and Vz are negative on the equator side and negative Vx and positive Vz on the pole side at high altitudes;(3)proton density is higher on the equator side than on the pole side.Results reported here will be useful in suggesting directions for future cusp research.

Global Statistical Study of Ionospheric Waves Based on COSMIC GPS Radio Occultation Data

Extracting and parameterizing ionospheric waves globally and statistically is a longstanding problem. Based on the multichannel maximum entropy method（MMEM） used for studying ionospheric waves by previous work, we calculate the parameters of ionospheric waves by applying the MMEM to numerously temporally approximate and spatially close global-positioning-system radio occultation total electron content profile triples provided by the unique clustered satellites flight between years 2006 and 2007 right after the constellation observing system for meteorology, ionosphere, and climate（COSMIC） mission launch. The results show that the amplitude of ionospheric waves increases at the low and high latitudes（~0.15 TECU） and decreases in the mid-latitudes（~0.05 TECU）. The vertical wavelength of the ionospheric waves increases in the mid-latitudes（e.g., ~50 km at altitudes of 200–250 km） and decreases at the low and high latitudes（e.g., ~35 km at altitudes of 200–250 km）.The horizontal wavelength shows a similar result（e.g., ~1400 km in the mid-latitudes and ~800 km at the low and high latitudes）.

Statistical study on the spatial - temporal distribution features of the arctic sea ice extent

On the basis of the arctic monthly mean sea ice extent data set during 1953-1984, the arctic region is divided into eight subregions,and the analyses of empirical orthogonal functions, power spectrum and maximum entropy spectrum are made to indentify the major spatial and temporal features of the sea ice fluctuations within 32-year period. And then, a brief appropriate physical explanation is tentatively suggested. The results show that both seasonal and non-seasonal variations of the sea ice extent are remarkable, and iis mean annual peripheral positions as well as their interannu-al shifting amplitudes are quite different among all subregions. These features are primarily affected by solar radiation, o-cean circulation, sea surface temperature and maritime-continental contrast, while the non-seasonal variations are most possibly affected by the cosmic-geophysical factors such as earth pole shife, earth rotation oscillation and solar activity.

A Statistical Study of XBLs,RBLs and FSRQs at 1.5 GHz

BL Lac objects are similar to the fiat spectrum radio quasars in many aspects except regarding the emission lines. In order to study their relationship, we selected 56 BL Lacertae objects （33 X-ray-selected, 23 radio-selected） and 45 flat spectrum radio quasars, analyzed their radio luminosities and core-dominance parameters. We found that the radio luminosities of the radio selected BL Lac objects located in between the X-ray selected BL Lac objects and the flat spectrum radio quasars. However, this intermediate position does not hold for the core-dominance parameter; the RBLs have the largest core-dominance parameters. This suggests that the core-dominance parameter can not be taken as a sequencing criterion. We also investigated the correlation between the luminosity and the core-dominance parameter for the three subclasses. We concluded that, here, the sequence XBL-RBL FSRQ still exists.

Study on Statistical Features About Weak Earthquake Activity Before Moderately Strong Earthquakes in the Middle Northern Part of the Qinghai-Xizang (Tibet) Block

In regards to the earthquakes recording M ≥ 5.0 that occurred in middle northern part of the Qinghai-Xizang （Tibet） Block from 1970 - 2003, in this study we describe the temporal and spatial centralization features of the weak earthquakes and the enhancement and anomalous quiescence of their seismic activity before main shocks through 4 parameters, which are basically not correlated： earthquake time centralization degree parameter Ct, earthquake space centralization degree parameter Cd, η value and weak earthquake frequency and so on. On the basis of calculation results, it has been seen that before earthquakes with M ≥ 5.0 took place in the middle northern part of the Qinghal-Xizang （Tibet） Block, the frequency of weak earthquakes often shows ascent and drop, their strength shows an obvious enhancement and the centralization distribution with time and space is evident.

A new method of studying the statistical properties of speckle phase

A new theoretical method with generality is proposed to study the statistical properties of the speckle phase. The general expression of the standard deviation of the speckle phase about the first-order statistics is derived according to the relation between the phase and the complex speckle amplitude. The statistical properties of the speckle phase have been studied in the diffraction fields with this new theoretical method.

Optimization of Strength Properties of Reactive Powder Concrete by Response Surface Methodology

The main objective of this study is to optimize the fresh and strength properties of reactive powder concrete incorporated with industrial by-products like ultra-fine ground granulated blast furnace slag as cement substitute and added with coal bottom ash and recycled concrete fines as partial replacement of quartz sand by response surface methodology through design of experiment approach.Totally four responses namely slump,compressive strength(C-28),flexural strength(F-28),and split-tensile strength(S-28)after 28 days of curing period were considered.The statistical study on the reactive powder concrete includes the modeling of regression,normal probability plots,surface plot analysis,and optimization of process variables.The regression models of the considered responses(slump,C-28,F-28,and S-28)were tested.The results obtained from the analysis of variance(ANOVA)and Pareto chart were used to determine the statistical significance of the process variables.The influence of the variables on the responses was studied by means of the surface plot analysis.The optimal proportion of the variables against the responses was obtained through optimization response.The resulted regression equations were in the form of second-order polynomial equation and the prediction of strength properties was found to be in line with the experimental results.The difference of proportion of variance indicated that only 0.43%,6.42%,5.15%,and 9.7%of deviations cannot be expressed by the analysis.The ANOVA and Pareto charts represented the high significance and appropriateness of the linear term of slump response and the two-way interaction term of strength responses.The results of the optimization response revealed the optimal proportions of recycled concrete fines and coal bottom ash as 19.15%and 7.02%,respectively.

A Preliminarily Statistic and Synoptic Study about the Basic Currents over Southeastern Asia and the Initiation of Typhoons

The relation between the basic currents of the low latitudes and the initiation of typhoons is investigated statistic-ally and synoptically by means of recent aerological data. It is shown that about 80% of typhoons developed in the eastern part of the equatorial convergence zone between the equatorial westerlies and trade wind of West Pacific Ocean. The equatorial westerly is a large scale and quasi-steady phenomenon; therefore, it is probably reasonable to be called ＂basic current＂ and typhoons are considered as vortices of smaller scale. There is a quite definite relation- ship between the time, position, frequency of the initiation of typhoons and the position, strength of the basic cur-rents in the low latitudes. There is a quasi-periodical variation of the strength and position of the basic currents with a period longer than one month. This fact may be helpful for the extended forecast the initiation and development of ty-phoons.

Study on the double transmission of ultrasonic waves through statistic rough surfaces

A model evaluating the signal loss of the double transmitted acoustic beams through random rough surfaces was established based on the Fresnel approximation and phase- screen approximation. A simple analytical solution was achieved using the exponential substi- tution approach to remove the nonlinear integral terms. The factors that affect the signal of double transmissions from random rough surfaces were analyzed. The research results demon- strated that the signal loss is not only related to the root-mean-squire height of the roughness, but also to the distance of wave traveling in the materials. The model can be very helpful for improving the reliability of NDT (Non-Destructive Testing).

A study on the statistics of sonic images

The statistics of sonic images obtained by an image sonar is analysed. The results show that the statistics of the sonic images is different from that of common TV images and, therefore, the processing methods for the sonic images possibly are different from that used for common TV images.

DESI Legacy Imaging Surveys Data Release 9:Cosmological constraints from galaxy clustering and weak lensing using the minimal bias model

We present a tentative constraint on cosmological parameters Ω_(m) and σ_(8) from a joint analysis of galaxy clustering and galaxygalaxy lensing from DESI Legacy Imaging Surveys Data Release 9(DR9),covering approximately 10000 square degrees and spanning the redshift range of 0.1 to 0.9.To study the dependence of cosmological parameters on lens redshift,we divide lens galaxies into seven approximately volume-limited samples,each with an equal width in photometric redshift.To retrieve the intrinsic projected correlation function w_(p)(r_(p))from the lens samples,we employ a novel method to account for redshift uncertainties.Additionally,we measured the galaxy-galaxy lensing signal ΔΣ(r_(p))for each lens sample,using source galaxies selected from the shear catalog by applying our Fourier Quad pipeline to DR9 images.We model these observables within the flatΛCDM framework,employing the minimal bias model.To ensure the reliability of the minimal bias model,we apply conservative scale cuts:r_(p)>8 and 12 h^(-1)Mpc,for w_(p)(r_(p))and ΔΣ(r_(p)),respectively.Our findings suggest a mild tendency that S_(8)=σ_(8)√Ω_(m)/0.3increases with lens redshift,although this trend is only marginally significant.When we combine low redshift samples,the value of S8is determined to be 0.84±0.02,consistent with the Planck results but significantly higher than the 3×2 pt analysis by 2-5σ.Despite the fact that further refinements in measurements and modeling could improve the accuracy of our results,the consistency with standard values demonstrates the potential of our method for more precise and accurate cosmology in the future.

On the systematic bias in the estimation of black hole masses in active galactic nuclei

In this report, we find the MBH estimated from the formalism of Wang et al. are more consistent with those from the MBH-δ, relation than those from previous single-epoch mass estimators, using a large sample of AGNs. Furthermore, we examine the differences between the line widths of Hβ and Mg II in detail by comparing their line profiles. The flux around the line core and that in the wing of both Hβ and Mg II show an opposite variation tendency, which indicates the BLR is multi-componential. The contribution of the wing makes the FWHM deviate from δline, and thus bias the MBH estimated from previous single-epoch mass estimators. Thus the correction on the formalism suggested by Wang et al. is crucial to MBn estimation.