单形的径向平均体

In this paper, it is proved that the radial pth mean body RpK（p 〉 0） is homothetic to the difference body DK when K is a simplex, Furthermore, the equality Rp（Rq） = Rq（Rp） is established when p 〉 0 and q 〉 0. It is also proved the Brunn-Minkowski inequality of radial pth mean body of simplex and uniqueness property.     

Structure and Magnetic Properties of Fe1-xCx Solid Solution Prepared by Mechanical Alloying

Supersaturated solid solutions Fe1-xCx （0≤x≤0.9 ） of wide composition range have been prepared by mechanical alloying process. Nanocrystalline phase was formed for 0 ≤ x ≤ 0.67 and a large grain phase for 0.75 ≤ x ≤ 0.9. The large fraction of graphite volume puts off formation of nanocrystalline phase for high carbon content. In the large grain phase, magnetization follows simple magnetic dilution, and eoereivity He is mainly due to dissolution of carbon at grain boundaries. In the nanocrystalline phase the alloying effect of carbon is revealed by a distinct reduction of average magnetic moment. The increasing lattice constant with increasing carbon content is observed for x ≤ 0.5, suggesting that the high carbon concentration may enhance diffusion of carbon into the Fe lattice. It shows a discontinuity in the Hc variation with a grain size D of nanocrystalline phase. For small grain D below the critical value, Hc increases with D. For a large grain D, Hc decreases with increasing D. The solubility limit of carbon in a-Fe extended by nanocry- stalline phase formation is discussed.     

Correlation of liquefaction resistance with shear wave velocity based on laboratory study using bender element

INTRODUCTION Evaluation of soil liquefaction resistance is an important aspect of geotechnical engineering practice, and several types of evaluating procedures have evolved over the last three decades. The well known “simplified procedure” originated by Seed and Idriss (1971) can be used to evaluate liquefaction resistance based on standard penetration test (SPT) blow counts. Over the years, the simplified procedure has been modified and updated with additional data, and has become th…     

Adsorption of Pb（Ⅱ） on Sediment of the Dianshan Lake：Adsorption Models and Kinetics

The adsorption characteristics of Pb on sediments of the Dianshan Lake in Shanghai was studied. The results show that (1)the relationship between the amount q of apparent equilibrium adsorption and the equilibrium concentration C conforms to the Freundlich isothermal adsorption equation; (2) the adsorption and desorption of Pb on sediments are not reversible, that is, adsorption/desorption of Pb exhibits hysteresis; (3) Pb adsorption behavior is initially fast, followed by a slow reaction, and the slow reaction conforms to a reversible first-order reaction; (4) by deducing the Pb adsorption kinetics, four kinetics parameters n, k1, k2, qmax independent of C could be worked out; (5) the equilibrium parameter (K) and the free energy change (ΔG) could also be determined,and the negative values of free energy change (ΔG) indicate the spontaneous nature of the adsorption.     

Generalized Derivations in Prime Rings

Let R be a ring, a ,b ∈ R, ( D , α ) and (G , β ) be two generalized derivations of R . It is proved that if aD ( x ) = G ( x )b for all x ∈ R, then one of the following possibilities holds: (i) If either a or b is contained in C , then α = β= 0 and there exist p , q ∈ Qr ( RC) such that D ( x )= px and G ( x )= qx for all x ∈ R;(ii) If both a and b are contained in C , then either a = b= 0 or D and G are C-linearly dependent;(iii) If neither a nor b is contained in C , then there exist p , q ∈ Qr ( RC) and w ∈ Qr ( R) such that α ( x ) = [ q ,x] and β ( x ) = [ x ,p] for all x ∈ R, whence D ( x )= wx-xq and G ( x )= xp + avx with v ∈ C and aw-pb= 0.     

Consistency across methods of observativn-an in-depth study of the cognitive preference test

If the same constructs embedded in different tests result in parallel or identical score patterns and high intercorrelations, this can be taken as evidence of construct validity. If results do not converge across instruments and/or response formats, this can be taken as evidence of lack of construct validity and/or impurity of the test as indicator of the constructs. In this study two response formats as well as a request for reasons-for-choices of the traditional Cognitive Preference Test (CPT), and an association (open-ended) CPT, were used in order to test for consistency across methods of observation on both the individual and the populational levels. Convergence of results was found to be minimal. None of the hypotheses was confirmed. It was concluded that construct validation of CPT constructs had not yet reached the state of unequivocality necessary for their application in curriculum research.     

Bearing capacity and failure mechanism of ground improved by deep mixed columns

Extensive research has investigated the bearing capacity of footings placed on leveled ground improved by deep mixed (DM) columns. However, few studies have focused on the effects of the embedment on the bearing capacity of footings on ground reinforced with DM columns. In geotechnical engineering practice underestimation of the limit load has occurred in China because of the increased use of conventional design methods for reinforced ground with embedment. In this investigation, a numerical model using a rigorous limit analysis tool, known as discontinuity layout optimization (DLO), is established. An equivalent area model is employed with an appropriate stress concentration ratio. Subsequently, a set of design charts of bearing capacity coefficients is produced with a special focus on the bearing capacity coefficient N_q and the failure mechanism. The results show that three failure patterns exist in the composite ground reinforced by DM columns. For cases without embedment, the bearing capacity coefficient N_c increases with the area replacement ratio to a certain value due to the occurrence of general shear failure mechanism. The bearing capacity coefficient N_γ decreases with the area replacement ratio, as the equivalent frictional strength of the reinforced region is reduced. When the embedment is considered, the failure mechanism of composite foundation has a significant influence on the coefficient N_q. Specifically, increase of column length leads to a larger value of N_q when block failure is observed. When a general shear failure pattern occurs, the effect of additional column lengths on the coefficient N_q can be neglected.     

Precise asymptotics in the law of the logarithm for random fields in Hilbert space

Consider the positive d-dimensional lattice d (d≥2) with partial ordering ≤, let {XK; K ∈ d } be i.i.d. random vari- ables taking values in a real separable Hilbert space (H, ||·||) with mean zero and covariance operator ∑, and set partial sums SN =∑K≤NXK, K , N ∈ d . Under some moment conditions, we obtain the precise asymptotics of a kind of weighted infinite series for partial sums SN as ε 0 by using the truncation and approximation methods. The results are related to the convergence rates of the law of the logarithm in Hilbert space, and they also extend the results of (Gut and Spǎtaru, 2003).     

On the Performance of Likelihood-Based Difference Tests in Nonlinear Structural Equation Models

This article investigates likelihood-based difference statistics for testing nonlinear effects in structural equation modeling using the latent moderated structural equations (LMS) approach. In addition to the standard difference statistic T_D, 2 robust statistics have been developed in the literature to ensure valid results under the conditions of nonnormality or small sample sizes: the robust T_DR and the “strictly positive” T_DRP. These robust statistics have not been examined in combination with LMS yet. In 2 Monte Carlo studies we investigate the performance of these methods for testing quadratic or interaction effects subject to different sources of nonnormality, nonnormality due to the nonlinear terms, and nonnormality due to the distribution of the predictor variables. The results indicate that T_D is preferable to both T_DR and T_DRP. Under the condition of strong nonlinear effects and nonnormal predictors, T_DR often produced negative differences and T_DRP showed no desirable power.     

Science Letters： New solutions of shear waves in piezoelectric cubic crystals

Acoustic wave propagation in piezoelectric crystals of classes?43m and 23 is studied. The crystals Tl3VS4 and Tl3TaSe4 (43m) of the Chalcogenide family and the crystal Bi12TiO20 (23) possess strong piezoelectric effect. Because the surface Bleustein-Gulyaev waves cannot exist in piezoelectric cubic crystals, it was concluded that new solutions for shear-horizontal surface acoustic waves (SH-SAWs) are found in the monocrystals using different electrical boundary conditions such as electri- cally “short” and “open” free-surfaces for the unique [101] direction of wave propagation. For the crystal Tl3TaSe4 with coefficient of electromechanical coupling (CEMC) Ke2=e2/(C×g)～1/3, the phase velocity Vph for the new SH-SAWs can be calculated with the following formula: Vph=(Va Vt)/2, where Vt is the speed of bulk SH-wave, Vt=Vt4(1 Ke2)1/2, Va=aKVt4, aK=2[Ke(1 Ke2)1/2-Ke2]1/2, and Vt4=(C44/ρ)1/2. It was found that the CEMC K2 evaluation for Tl3TaSe4 gave the value of K2=2(Vf–Vm)/Vf～0.047 (～4.7%), where Vf～848 m/s and Vm~828 m/s are the new-SAW velocities for the free and metallized surfaces, respectively. This high value of K2(Tl3TaSe4) is significantly greater than K2(Tl3VS4)～3% and about five times that of K2(Bi12TiO20).     

Numerical simulation of mechanical behaviors of degradable porous bioceramics with cracks

Hydroxyapatite bioceramics is simulated by using finite element method (FEM).The influences of porosity,hole shape,angle of crack and other parameters on the ceramics are analyzed.The results show that with the increase of the angle between crack and horizontal direction,the stress intensity factor KⅠdecreases gradually,but stress intensity factor K II increases at first and then it decreases.The value of K Ⅱ reaches maximum when the angle between crack and horizontal direction is 45°.KⅠ and K Ⅱ rise with the increase of porosity,and they are almost the same for the circular and hexagonal holes.For elliptical holes,KⅠand KⅡreach maximum when the long axis of ellipse is perpendicular to the loading direction and they reach minimum when the same axis is parallel to the loading direction.Moreover,with the increase of the angle between the long axis and loading direction,KⅠ and KⅡ increase gradually.     

Self-Regulation and Academic Measures Across the Early Elementary School Grades: Examining Longitudinal and Bidirectional Associations

ABSTRACT

This study evaluated the association between children’s (N = 301) self-regulation and math and reading achievement in kindergarten, 1st grade, and 2nd grade. Children’s self-regulation was assessed using the Head–Toes–Knees–Shoulders (HTKS) task (involving control of gross body movements) and a computerized continuous performance task (CPT; assessing primarily inhibitory control) in kindergarten, 1st grade, and 2nd grade. Research Findings: Based on cross-lagged structural equation panel models, HTKS task performance positively predicted later math and reading achievement. Math achievement significantly and positively predicted later HTKS and CPT scores. Earlier math and reading achievement moderated the association between CPT scores and later math and reading achievement; inhibitory control–based self-regulation assessed with the CPT predicted higher math or reading achievement in subsequent grades for children with lower math or reading achievement in prior grades. Performance on the CPT moderated the paths from HTKS scores to later reading achievement; behavioral self-regulation assessed with the HTKS task predicted higher reading achievement in subsequent grades for children with low or average CPT performance in prior grades. Practice or Policy: Results from this study have the potential to inform targeted academic interventions focused on enhancing self-regulation in school contexts. The findings highlight the utility of assessing multiple measures of self-regulation.     

Fe-Ni系列合金超细粉末的磁性和有效磁各向异性常数

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Non-monotonic piezocone dissipation curves of backfills in a soil-bentonite slurry trench cutoff wall

Pore pressure dissipation during piezocone testing provides a unique tool for estimating the hydraulic properties of in-situ backfills in soil-bentonite (SB) slurry trench cutoff walls. Six tests were performed in an SB slurry trench cutoff wall located in Jiangsu Province, China. The pore pressure dissipation curves obtained are non-monotonic, which, as far as the authors are aware, is reported for the first time in SB cutoff walls. The non-monotonic dissipation curves are attributed to the redistribution of excess pore pressures between the base soil clods and the rest of the backfill around the cone. Four existing interpretation methods are adopted to analyze the measured non-monotonic piezocone dissipation curves. The horizontal coefficients of consolidation (c_h) of the backfills obtained by three methods are close to each other and in agreement with the results of fixed-ring consolidometer tests, while the other method gives a high overestimate. The hydraulic conductivities (k_h) of the backfills are also estimated by four methods, three based on dissipation test results and one based on piezocone penetration data. k_h estimated by consolidation theory are close to the results of flexible wall permeameter tests. Two empirical expressions for dissipation tests give relatively low k_h, but the method based on penetration gives k_h much larger than the laboratory test results.     

Organic nitrogen components in soils from southeast China

Objective:To investigate the amounts of extractable organic nitrogen(EON),and the relationships between EON and total extractable nitrogen(TEN),especially the amino acids(AAs) adsorbed by soils,and a series of other hydrolyzed soil nitrogen indices in typical land use soil types from southeast China.Under traditional agricultural planting conditions,the functions of EON,especially AAs in the rhizosphere and in bulk soil zones were also investigated.Methods:Pot experiments were conducted using plants of pakchoi(Brassica chinensis L.) and rice(Oryza sativa L.).In the rhizosphere and bulk soil zone studies,organic nitrogen components were extracted with either distilled water,0.5 mol/L K2SO4or acid hydrolysis.Results:K2SO4-EON constituted more than 30% of TEN pools.K2SO4-extractable AAs accounted for 25% of EON pools and nearly 10% of TEN pools in rhizosphere soils.Overall,both K2SO4-EON and extractable AAs contents had positive correlations with TEN pools.Conclusions:EON represented a major component of TEN pools in garden and paddy soils under traditional planting conditions.Although only a small proportion of the EON was present in the form of water-extractable and K2SO4-extractable AAs,the release of AAs from soil exchangeable sites might be an important source of organic nitrogen(N) for plant growth.Our findings suggest that the content of most organic forms of N was significantly greater in rhizosphere than in bulk soil zone samples.However,it was also apparent that the TEN pool content was lower in rhizosphere than in bulk soil samples without added N.     

Revisiting the Model Size Effect in Structural Equation Modeling

Fitting a large structural equation modeling (SEM) model with moderate to small sample sizes results in an inflated Type I error rate for the likelihood ratio test statistic under the chi-square reference distribution, known as the model size effect. In this article, we show that the number of observed variables (p) and the number of free parameters (q) have unique effects on the Type I error rate of the likelihood ratio test statistic. In addition, the effects of p and q cannot be fully explained using degrees of freedom (df). We also evaluated the performance of 4 correctional methods for the model size effect, including Bartlett’s (1950), Swain’s (1975), and Yuan’s (2005) corrected statistics, and Yuan, Tian, and Yanagihara’s (2015) empirically corrected statistic. We found that Yuan et al.’s (2015) empirically corrected statistic generally yields the best performance in controlling the Type I error rate when fitting large SEM models.     

Biofuel from<Emphasis Type="Italic">D</Emphasis>-xylose — The second most abundant sugar

In the biosphere we find cellulose and hemicellulose as the major polysaccharides. On acid or enzymatic hydrolysis,D-glucose is produced from cellulose andD-xylose is produced from xylans as the major sugar in the hydrolysate. Initially it was believed that yeasts do not fermentD-xylose to ethanol although many are capable of producing xylitol. Twenty years ago, a few yeasts that could convertD-xylose to ethanol were found. Ethanol is viewed as a potential fuel that is available from biomass and hence new methods to generate ethanol from hitherto inaccessible sources are gaining importance. Biotechnology for efficient utilization of lignocellulose wastes as fuels relies on the utilization of both the cellulosic as well as hemicellulosic portions of the biomass. In this article, conversion of xylose into ethanol is discussed.     

Varietal differences in photosynthetic characters and chlorophyll fluorescence induction kinetics parameters among intergeneric progeny derived fromOryza×Sorghum, its parents, and hybrid rice

A comparative study on the photosynthetic parameters among intergeneric progenies derived fromOryza sativa L.×Sorghum vulgare L., its maternal parent Gui 630 and commercial 3-line hybrid rice Shanyou 63 in pot experiment in greenhouse was conducted. The morphological and photosynthetic characters of canopy leaves and chlorophyll fluorescence kinetic parameters includingF _v/F _m,F _v/F ₀, photochemical quenching coefficient and non-photochemical coefficient of canopy leaves of 3 varieties were measured. The results showed the progeny, Yanyou 1, derived from an intergeneric cross of rice and sorghum possesses better canopy spatial architecture with thicker, heavier and bigger canopy leaf than its maternal parent Gui 630. Higher photosynthetic rate due to higher chlorophyll content, higher primary energy transformation efficiency, potential of PSII and non-photochemical quenching coefficient (q _E) were also measured in Yuanyou 1. These explain partly why the intergeneric progeny has higher biomass production, and better tolerance to adverse conditions and higher field yields even under stress conditions.     

Molten Salt Synthesis of （K0.47Na0.47Li0.06） NbO3 Lead-Free Piezoelectric Ceramics

(K0.47Na0.47Li0.06)NbO3 (KNLN) lead-free ceramics were prepared by molten salt synthesis (MSS) method using k2CO3-Na2CO3 eutectic mixtures as the flux. The microstructure and piezoelectric properties when sintered at 980-1 030 ℃ were investigated. The calcined powders were examined by X-ray diffraction. The microstructure of the calcined powders and sintered bodies was observed using a scanning electron microscope (SEM).The piezoelectric constant d33 was measured using a quasi-static piezoelectric d33 meter. The planar coupling coefficient Kp was calculated by resonance-antiresonance method. The experimental data for each sample's performance indicators were the average values of 8 specimens. The relative densities of sintered specimens are above 97%, and the dielectric loss is below 0.03. It was found that (K0.47Na0.47Li0.06)NbO3 prepared by MSS is compact and lead-free. The piezoelectric constant d33 is 216 pC·N-1 and the planar electromechanical coupling factor Kp is 0.352.     

Influence of pinning center distribution on the pinning of two-dimensional vortex system

The superconductor sample had periodic distribution of pinned region (with length ofL _p) and unpinned region (with length ofL−L _p) along the driving force direction. Numerical study on the influence of the distribution of pinning centers on pinning of the two-dimensional vortex system showed that the critical depinning forceF _c, beyond which the vortex system begins to depin, increases with increase ofL _p, indicating that the homogeneity of pinning centers helps to enhance the critical electric current of a superconductor. We found that the critical depinning forceF _c depends logarithmically onL/L _p. Project supported by the Ministry of Science and Technology of China (NKBRSF-G19990646) and Zhejiang Proviace Foundation (199031).