n阶非齐次线性方程解的线性相关性

对常微分方程中的n阶非齐次线性方程进行了讨论,给出了其解的线性相关性的一些性质定理,并进行了严格证明,加深了对n阶非齐次线性方程解的特征的认识.

基于CRITIC-TOPSIS法地铁车站基坑开挖施工安全风险评估——以济南地铁9号线开源路站为例

地铁车站基坑通常因规模大、近接建构筑物、对变形控制的要求高,而成为地铁车站建设中重点关注的环节。如何对地铁车站基坑开挖施工进行科学有效的评估,使其对施工工法及技术进行优化和指导,降低地铁车站建设时带来的风险,有至关重要的意义。应用指标相关性权重确定(CRITIC)法,并结合逼近理想解排序(TOPSIS)法,依托在建地铁车站基坑项目进行评估。结果表明:周边环境与支护不足成为地铁车站基坑开挖施工的主要风险来源;对于狭长型的地铁车站基坑来说,端头井处较易发生危险。通过使用CRITIC-TOPSIS法对地铁车站基坑开挖施工进行安全风险评估,可有效分析基坑开挖中的风险因素并按照影响程度进行大小排序,针对具体因素采取有效措施以减小施工风险。

超声弹性成像技术中一种新的组织压缩仿真模型

组织压缩仿真模型在超声弹性成像技术中,对应变估计与成像算法的设计和性能评估起着非常重要的作用。基于组织超声分立散射模型,提出一种新的组织压缩仿真模型。该模型通过设计信号幅度和相位参数的不同变化,可以实现压缩前后信号可控的解相关性。与其他仿真模型相比,该模型还具有解相关性随检测深度变化的特点。离体组织压缩实验验证了该模型的有效性。

Biological Characteristics of Biosurfactantproducing Petroleum-degrader Bacterium Bacillus BS-8

The growth characteristics of petroleum-degrader BS-8（Bacillus sp.） and the factors influencing its biosurfactant production were tested; the biosurfactant releasing mode of BS-8 was speculated by measuring OD600, surface tension and oil displacement of fermentation broth; and the effects of carbon source, nitrogen source, temperature, p H, and Na Cl concentration on biosurfactant production by BS-8 were observed in this study. The results showed that the biosurfactant releasing mode of BS-8 was growth-correlated, the surface tension of BS-8 fermentation broth declined with the total bacteria increasing, and the oil displacement was positive correlated with biosurfactant content in fermentation broth; and the optimal culture conditions for effective biosurfactant production included： glucose as carbon source,yeast extract as nitrogen source, Na Cl concentration of 2%, p H of 7.0 and temperature at 30 ℃.

Measurement and Correlation for Solubility of Adipic Acid in Several Solvents

Using a laser detecting system, solubility data were measured for adipic acid dissolved in six pure solvents, namely, cyclohexanone, cyclohexanol, acetic acid, N,N-dimethylformamide, N,N-dimethylacetamide, and dimethylsulfoxide at the temperature range from 293.15K to 353.15K. All these data were regressed by 2h, NRTL, Wilson, and the modified Wilson models. For the study of six, 2h, NRTL, and the modified Wilson models were found to provide an accurate mathematical representation of the experimental results, with overall average absolute relative deviations between measured and calculated values as 1.74%, 2.06%, and 3.06%, respectively. The results showed that the λh model is the most suitable for description of the solid-liquid equilibrium containing adipic acid.

Effect of Reduction Associated with Organic Matter Decomposition on Magnetic Properties of Red Soils

Five soils derived from different parent materials were sampled from red soilregion of southern China and studied by magnetic methodology to understand to what extent ironreduction would affect soil magnetic properties and how iron reduction would affect the magneticminerals in soils. Reduction associated with organic matter decomposition strongly affected soilmagnetic parameters at low pH. The losses of original soil magnetic signals in terms of magneticsusceptibility (X), 'Soft' isothermal remanent magnetization ('Soft' IRM), anhysteretic remanentmagnetization (ARM) and saturation isothermal remanent magnetization (SIRM) at pH 4～6 during thetwo-month saturation treatment, were 66%～94%, 54%～90%, 64%～95% and 33%～83%, respectively. Thesechanges were interpreted as a consequence of substantial dissolution of maghaemite and haematite inthe soils. At pH 10, however, there was no significant magnetic change observed. Moreover, stablesingle domain soil maghaemite grains were also sensitive to reduction, which suggested that bothpedogenic and detrital maghaemite were not stable in acid and reducing environments. Goethite,instead, was the most stable iron form under reducing conditions.

Outlet Temperature Correlation and Prediction of Transfer Line Exchanger in an Industrial Steam Ethylene Cracking Process

Predicting the best shutdown time of a steam ethylene cracking furnace in industrial practice remains a challenge due to the complex coking process. As well known, the shutdown time of a furnace is mainly determined by coking condition of the transfer line exchangers （TLE） when naphtha or other heavy hydrocarbon feedstocks are cracked. In practice, it is difficult to measure the coke thickness in TLE through experimental method in the complex industrial situation. However, the outlet temperature of TLE （TLEOT） can indirectly characterize the coking situation in TLE since the coke accumulation in TLE has great influence on TLEOT. Thus, the TLEOT could be a critical factor in deciding when to shut down the furnace to decoke. To predict the TLEOT, a paramewic model was proposed in this work, based on theoretical analysis, mathematic reduction, and parameters estimation. The feasibility of the proposed model was further checked through industrial data and good agreements between model prediction and industrial data with maximum deviation 2% were observed.

The Life of a Protein Molecule——Protein Quality Control

The research progress in molecular chaperones, unfolded protein response （UPR） and ER-associated degradation （ERAD） involved in the protein quality control was summarized in this paper, and then the existing problems and the future devel- opment prospect were also discussed. It was pointed out that the life process of protein experienced four stages including synthesizing, folding, assembling and degradation, while each stage required strict quality control. In endoplasmic reticulum （ER）, a variety of proteins had been synthesized, folded and modified to form func- tional proteins with certain conformation. When the folding was blocked in ER, the unfolded proteins would aggregate and induce the UPR, which up-regulated the level of modification enzymes folded by a series of molecular chaperones and proteins to help them accomplish folding and assembling. If these proteins were still folded incorrectly, they would enter into ERAD for being degraded.

One New Method to Obtain the Correlation Length of Solvable Models

We propose a new method to obtain the correlation length of gapped XXZ spin 1/2 antiferromagnetic chains. Following the relativistic quantum field theory in space-time dimensions, we use the exact dispersion of massive spinon to calculate the correlation length for XXZ spin 1/2 chain. We conjecture that the correlation length for other 1D lattice models can be obtained in the same way. Relation between dispersion and the oscillated correlation of gapped incommensurate lattice models is also discussed.

Correlation Between CO_2 Efflux and Net Nitrogen Mineralization and Its Response to External C or N Supply in an Alpine Meadow Soil

In nutrient-limited alpine meadows,nitrogen(N) mineralization is prior to soil microbial immobilization;therefore,increased mineral N supply would be most likely immobilized by soil microbes due to nutrient shortage in alpine soils.In addition,low temperature in alpine meadows might be one of the primary factors limiting soil organic matter decomposition and thus N mineralization.A laboratory incubation experiment was performed using an alpine meadow soil from the Tibetan Plateau.Two levels of NH4NO3(N) or glucose(C) were added,with a blank without addition of C or N as the control,before incubation at 5,15,or 25 ℃ for 28 d.CO2 efflux was measured during the 28-d incubation,and the mineral N was measured at the beginning and end of the incubation,in order to test two hypotheses:1) net N mineralization is negatively correlated with CO2 efflux for the control and 2) the external labile N or C supply will shift the negative correlation to positive.The results showed a negative correlation between CO2 efflux and net N immobilization in the control.External inorganic N supply did not change the negative correlation.The external labile C supply shifted the linear correlation from negative to positive under the low C addition level.However,under the high C level,no correlation was found.These suggested that the correlation of CO2 efflux to net N mineralization strongly depend on soil labile C and C:N ratio regardless of temperatures.Further research should focus on the effects of the types and the amount of litter components on interactions of C and N during soil organic matter decomposition.

A block-based secure and robust watermarking scheme for color images based on multi-resolution decomposition and de-correlation

This paper presents a block-based secure and robust watermarking technique for color images based on multi-resolution decomposition and de-correlation.The principal objective of the presented scheme is to simultaneously meet all the four requirements(robustness,security,imperceptibility,and capacity)of a good watermarking scheme.The contribution of this study is to basically achieve the four contradictory requirements that a good watermarking scheme must meet.To do so,different approaches are combined in a way that the four requirements are achieved.For instance,to obtain imperceptibility,the three color channels(red,green,and blue)are de-correlated using principal component analysis,and the first principal component(de-correlated red channel)is chosen for watermark embedding.Afterwards,to achieve robustness,the de-correlated channel is decomposed using a discrete wavelet transform(DWT),and the approximate band(the other three bands are kept intact to preserve the edge information)is further decomposed into distinct blocks.The random blocks are chosen based on a random generated key.The random selected blocks are further broken down into singular values and vectors.Based on the mutual dependency on singular values and vectors’matrices,the values are modified depending on the watermarking bits,and their locations are saved and used as another key,required when the watermark is to be extracted.Consequently,two-level authentication levels ensure the security,and using both singular values and vectors increases the capacity of the presented scheme.Moreover,the involvement of both left and right singular vectors along with singular values in the watermarking embedding process strengthens the robustness of the proposed scheme.Finally,to compare the presented scheme with the state-of-the-art schemes in terms of imperceptibility(peak signal-to-noise ratio and structural similarity index),security(with numerous fake keys),robustness(normalized correlation and bit error rate),and capacity,the Gonzalez and Kodak datasets are used.The comparison shows significant improvement of the proposed scheme over existing schemes.

A pest control model with state-dependent impulses

In this paper, a pest control model with state-dependent impulses is firstly established, which relies on releasing of natural enemies, together with spraying pesticides. By using the successor function of differential equation geometry rules, the existence of order one periodic solution is discussed. According to the Analogue of Poincare＇s Criterion, the orbitally asymptotic stability of the order one periodic solution is obtained. Furthermore, we investigated the global attractor of the system. From a biological point of view, our results indicate that： （1） the pest population can be controlled below some threshold; （2） compared to single measure, it is more efficient to take two measures for reducing the level of the pests.