By letting K be a finitely generated field extension of k and v be a k-valuation of K, we define the height of the valuation. Based on this we obtain the complete classification of valuations on surfaces. In addition, we get the relationship between the valuation and transcendental power series.
A kind of linear estimator is derived in linear regression model. The superiorities of the linear estimator over least square (LS) estimator are studied in terms of the mean square error matrix (MSEM) criterion and Pitman closeness (PC) criterion. Finally, the superiorities of the linear estimator of estimable function for regression coefficients are discussed in non-full rank case.
We fully classify the quantum pure state of 2×5×5 system under stochastic local operations and classical communication. We find all together 34 inequivalent classes, 3 of which have non-local parameters. One of them has two non-local parameters, and the other two have only one. The parameters are not completely arbitrary. We find that the parameters have some symmetry properties, and there is a D3 symmetry for the case of one parameter.
A fluorinated indiumphosphate, InF2 2(NH4)3, has been prepared under ionothermal condition using deep-eutectic solvents of choline chloride and urea as solvent and template-delivery agents. The same material can not be observed with the presence of the same deep-eutectic mixture under normal hydrothermal process. The compound crystallized in the monoclinic system, space group C2/c (No.15) with cell parameters a=13.799(3) , b=5.091(2) , c=16.094(3) , β=112.942(16)°, V=1041.2(5) 3 and Z=4; the final residual factors were R1=0.0582 and wR 2=0.1589. The structure is built from an infinite chain composed of interconnected 4-member ring with formula of InF2 3-2. The guest ammonium are hydrogen bonded to the F atoms located in two outmost vertexes of indium octahedral and terminal P—OH and P O groups in the chain respectively. The integrated framework is formed by van der Waals forces holding the chains together as extensive H bond array exists in the compound. The further characterizations of the compound have been performed by X-ray powder diffraction, EDX, IR, XPS and TG/DTA analyses.
The total polyphenols(TP)content of Quercus mongolicus Fisch leaves extracts was analyzed by Folin-ciocalteu colorimetry,with gallic acid as standard.The method was improved and verified in the aspects of stability, linearity,precision and accuracy.The results showed that the total polyphenols content of Quercus mongolicus Fisch leaves extracts could be well calculated according to their colorimetric absorption at 760nm by applying Folin-ciocalteu reagent (1mol/L) 0.15mL and 10% volume fraction of Na2CO3 0.15mL at 25℃ for 80min. The (TP)content in Quercus mongolicus Fisch leaves determinated by the method was 6.39% and RSD was 1.90%.
Based on the soil temperature data from Shenzhen climatic observatory, the diurnal variation of the soil temperature and its profiles in winter in Shenzhen city were analyzed under different types of weather condition. The soil temperature above 160cm has different diurnal variations under different weather conditions and the cold air has greatest effects. The soil temperature below 160cm deep has very small diurnal variation whether it is a sunny, overcast or rainy day with or without cold air effects.
To investigate the decolorizational characteristics of Congo red by fungi, a fungal strain of Cuuninghamella echinulata was screened in the study of decolorization of azo dye Congo red. It was found that the decolorization rate of Congo red by Cuuninghamella echinulata mycelia pellets could be attained at 96% in 3h. Under agitated condition, the effects of initial pH, temperature, shaker speed and salt concentration on decolorization rate were studied. The results showed that the optimum pH, temperature and shaker speed were 6.5, 33℃ and 120r/min, respectively. In addition, the influence of salt concentration on the decolorization rate was slight. In the Congo red concentration range of 50~200mg/L, the decolorization kinetics of Congo red fitted with pseudo-second-order equation curve(R2>0.999). Moreover, the Langmuir and Freundlich models had been used to describe the isotherm adsorption data for Congo red onto mycelia pellets, and the parameters indicated that the Langmuir model was a better description for the isotherm adsorption(R2>0.999).
Preserving genetic diversity on farms is crucial to global agriculture, and effective programs to promote such conservation depend on farmers' choice among different crops. Farmers in remote regions of northern China continue to grow diverse minor grain crops of local varieties with rich genetic resources. We conducted a household survey to better understand farmers' choice. Based on the proposed crop choice model, we find that the low socioeconomic status and the incompleteness of the markets are the two main reasons. The present study suggests that the government should invest more on genetic diversity preserving.
Data of 1024 samples collected from a 10.24hm2 crop land in dense grid of 10m×10m were used to analyze the scaling effect on spatial variability of soil organic matter(SOM)by re-sampling to change sampling extent and resolution.Within the sampled area, soil organic matter had weak variability as CV≤3.43%, but it was entirely low in the content no more than 1.04%.The results showed that spatial variability of soil organic matter increased with the ascending extent at different degrees, while spatial dependency and correlation distance increased distinctly.With contrast to the change of extent, descending resolution can not result in spatial variability of SOM varying orderly, but descended spatial dependency, and increased the correlation distance constantly.
The study of mantle transition-zone shows that velocity discontinuities of 410km and 660km were caused by phase-change. Subduction through these two discontinuities will change the depth of the discontinuities. A flat subduction slab lying on the 660km was observed in North-East China subduction-zone by seismic imaging, and a deeper 660km discontinuity was reported by receiver function studies. But the receiver function results in Tibetan collocation zone does not show any significant elevation or depression of the discontinuities. To exam whether there is no subduction-slab through the discontinuities in these areas, or we have not observed the discontinuity caused by subduction-slab, we carry out a thermal simulation in the area, and compute the possible elevation and depression of the discontinuities. We have considered subduction models with different angles and a model the whole Tibetan plateau was thicken by Indian lithosphere. When we only consider the Olivine-Spinel phase change as the cause of 410km velocity discontinuity, and Olivine-Perovskite phase change as the cause of the 660km velocity discontinuity, our result shows that the subduction similar to our models will change the depth of discontinuities significantly, and could be observed by seismic receiver function method. According to our results and the receiver function results, we tend to support the opinion that there does not exist deep subduction slab in Southern Tibet, and the subduction may go further north.
The study area "Poyang Lake area" is referred to humid environment and complex land coverage. In this paper, a component evapotranspiration model for wetland is developed based on component net radiance flux, component soil heat flux and component temperature through simplifying the complex processes of land-atmosphere interaction and analyzing vital factors which influence regional evapotranspiration. In the experiment the MODIS component proportion images with the 1km pixel are created according to TM classified images. Considering the difference of effect caused by different components on net radiance flux, the component net radiance flux is calculated using component proportion, component temperature and component albedo. The daily evapotranspiration distribution in Poyang Lake wetland is finally obtained. The new model is validated using residual method, field surveying data and history meteorological data. The result shows that the evapotranspiration acquired by the new model in Poyang Lake wetland is credible, and it can reflect the distribution of evapotranspiration in wetland objectively.
Site effects are analyzed for the Chelongpu fault area using the aftershock strong-motion data of the 1999 Chi-Chi, Taiwan, earthquake. Four techniques are used including traditional spectral ratios of S wave, generalized inversion technique, receiver function of S wave and genetic algorithm. Our results show that the predominant frequencies for each site estimated by these four methods are almost the same. However, the site amplifications for each site obtained by these methods have some differences. The results of generalized inversion technique and the traditional spectral ratio method are affected by the reference site. After corrected by the site effect of the reference site obtained by genetic algorithm, the corrected results of the generalized inversion technique agree well with the results of genetic algorithm. This shows that genetic algorithm is a reasonable technique to estimate the absolute site effect for a site. In this study, usually, the site amplification obtained by the method of the receiver function is larger than other three techniques. Considering there are still many unclear issues in this method, we suggest that one should be very careful when using receiver function to estimate the site effect. Finally, we gave the QS-value calculated by generalized inversion technique. It is frequency dependent, QS=69.7f?0.73, in the range of frequency 0.4~20Hz.
The snow-covered area plays an important role in the global energy balance. The most popular retrieval algorithms are derived mainly from regression techniques using the normalized difference snow index(NDSI),but these methods are in low precision where the snow fraction is near 1 or 0. In this study, a segmentation model proposed to retrieve the snow fraction using moderate resolution imaging spectroradiometer(MODIS) datasets is finally validated by using the ETM+ imagery,which indicates that the fraction of snow cover within a MODIS pixel can be estimated effectively, and especially it can improve the precision in the area where the snow fraction is near 1.
Through reasoning about PKI trust model, researchers can learn more about the establishment and transfer of trust relationships in PKI systems. Based on the existing models, we proposed a set of trust logics with practical predications and trust parameters. By utilizing these logics, we have extended the derive formulas for entity's authentication and authorization and analyzed the relationship between PKI structure and trust probabilistic.
We investigated the representation methods for text classification, proposed the framework of analyzing Chinese text representation algorithms, analyzed the influence of text representation, and obtained the influence of variable text representation factors on classification effect. Using Chinese characters can directly obtain better effect than expected; there is little difference on classification effect among splitting articles with smaller or huger dictionary or even by complicated splitting algorithm; and classification with only 01 to represent whether a feature is presented in a text or not can lead to not bad effect. We also found it can greatly improve classification effect to use reasonable vector value such as suitable formalization algorithm. These conclusions have provided instructions to contifurther applications.
Source code analysis means detecting and correcting the security vulnerabilities of these software in time during the coding stage, and lexical analysis is one of the important techniques in it. In this paper, we manage to detailedly analyze the implement process of lexical analysis, improve dangerous function database, optimize the method of features analysis,and particularly introduce Bayesian theory to the lexical analysis. In addition, a lexical analysis tool SSCAN is designed and implemented successfully, which is proved to have higher integrity and accuracy than mainstream open-source lexical analysis software Flawfinder and Rats by several tests.
Uranium dioxide is a kind of steady nuclear fuel that has the characteristic of high melting point and steady property. The thermal conductivity of uranium dioxide can directly influence the temperature distribution of nuclear fuel and the max temperature of the center of nuclear fuel. The experimental results and expression of thermal conductivity have been compared in the paper. The deviation between the experiment results has decreased. The non-equilibrium molecular dynamics simulation results are in good agreement with the experiment results in medium temperature region. In low temperature region, it is necessary to add the quantum correction to the kinetic energy computation of phonon. In high temperature region, it is needed to use the accurate potential model and build up the electron gas energy transport model and photon radiation energy transport to study the thermal conductivity well and truly for the nuclear reactor safety design and uranium dioxide engineering application.
Two effective allocation schemes are proposed for Multiuser MIMO-OFDM systems with zero-forcing beamforming. Through adaptive power,subacarrier and bit allocation, our objective is to minimize the total transmit power while satisfying the target data rates of all users. The numerical results show that the two proposed sub-optimal methods can achieve good performance while satisfying the rate demand of users.
We have studied the physical and chemical properties of some novel materials from first principles. A variety of materials with different dimensions (from solid, surface, and nanotube to molecule) are studied.