微尺度滑动平均方法计算海浪谱奇阶矩的公式

Glazman提出了一种计算海浪谱高阶谱矩的微尺度平均方法 ,但是 ,他利用随机过程理论导出的计算偶阶矩的公式和参照偶阶矩结论定义的奇阶矩计算公式之间存在着内在的不一致性 .本文在Glazman工作的基础上根据随机过程理论推导了“微尺度平均方法”计算奇阶谱矩的公式 ,纠正了他的错误 .上述结论随即应用于讨论破碎对波面水质点水平速度分布的影响 .通过破碎的加速度判据考虑了破碎对速度分布的限制 ,给出了未破碎波面上水质点水平速度的的统计分布的初步结果 .该分布取决于谱宽度参数及白浪覆盖率的大小 。

基于隐马尔可夫模型的引文信息提取

提出一种基于符号特征提取的HMM结构学习方法，并利用修改的Viterbi算法进行引文信息提取。在实验结果的评价上，除了常用的准确率(Precision)、查全率(Recall)、综合评价指标(F)之外，引入了两个评价标准：宏平均和微平均来综合评价算法的性能。试验表明该方法用于引文信息提取的正确率较高。

自注意力机制的短文本分类算法

分析目前的短文本分类算法没有综合考虑文本中隐含的依赖关系和局部关键信息这一问题,提出基于自注意力机制(self-attention mechanism)的堆叠双向长短时记忆网络(stack bidirectional long short term memory)模型(简称Att-BLSTMs)。利用stack Bi-LSTMs捕获上下文隐藏依赖关系,优化短文本特征稀疏的问题;利用自注意力机制加大对短文本中局部关键信息的注意力,优化文本表示。在公开AG-news网页新闻的语料和DBpedia分类数据集中,进行丰富的对比实验。实验结果表明,该模型将文本中隐含依赖关系与局部关键信息综合考虑后,有效提高了短文本分类的准确性。

基于PLSA模型的观点句聚类算法研究

针对互联网评论文本中观点句情感特征的稀疏性及低频性,提出一种基于概率潜在语义分析(PLSA)模型的观点句聚类算法。利用PLSA对语料库中的观点句进行数据预处理与数据聚类,并以微平均F1为评价指标设计与采用潜在语义分析(LSA)方法的对比实验。分析与研究结果表明:(1)主题数在20附近时,聚类效果最为显著;主题数超过20时,聚类效果随着主题数的增加呈递减趋势,之后聚类效果趋于稳定;(2)与LSA算法相比,PLSA算法显示出较好的聚类效果,数据测试结果验证了该模型的有效性。研究结果对提高信息检索速度与个性化推送服务具有重要意义。

ALBERT与双向GRU的多标签灾情信息预测

针对灾害求助信息辨识不准确、响应能力不足的问题,提出了基于ALBERT(a lite bidirectional encoder representation from transformers)和双向GRU(gate recurrent unit)的文本多标签分类模型。首先利用ALBERT预处理语言模型对文本信息进行编码,获取文本的动态词特征向量,并送入双向GRU神经网络进行训练,根据不同的单词赋予不同的权重,应用Attention机制进行解码。利用模拟退火算法求解最优阈值,以微平均值作为评价函数,确定样本的标签类别归属。与逻辑回归、朴素贝叶斯和长短期记忆(long-short term memory,LSTM)神经网络等模型进行比较。结果显示,多标签分类模型具有更高的准确率,达到95%,汉明损失仅到0.05,能够更好地辨别灾情求助信息,提高救援效率。

Microscopic Structure of Rabbit Hair

[Objective] The paper was to explore the microscopic structure of rabbit hair. [Method] Single rabbit hair with typical features was selected to observe its mi- croscopic structure from tip to root, and its fiber diameter was also measured. [Result] The rabbit hair tip was constituted by scale layer and cortical layer, without medullary layer; the middle part was generally constituted by scale layer, cortical layer and medullary layer; the root had no medullary layer, and the scale layer was wheatear-shaped. This was the property of rabbit hair, which could be used for comparative studies with other animal fiber and species identification. Rabbit hair had developed medullary layer, and fiber diameter was positively related to column number of medullary cavity. The hair generally was single column, and coarse hair was multi-column. Single rabbit hair was the finest in the tip, coarse in the middle and tapering in the root. The diameter difference of various parts was large, and the ex- ternal growth characteristics was spindle-shaped. [Conclusion] Using biological micro- scope method to identify different animal fur and product species is more objective and simple.

Microbial Community Characteristics in the Rhizosphere of Atrazine-contaminated Soil by Dendroremediation of Poplar

The change of microbial community characteristics in the different rhizo- sphere zones of hybrid poplar （Populusdeltoidsxnigra, DN34） under atrazine stress were investigated by rhizo-boxes and Biolog system in a greenhouse experiment, with sublimed sulfur and calcium hydroxide as soil pH regulators. Data from the measurement by the Biolog ECO plate demonstrated that the value of average well color development （AWCD） and the carbon source utilization of soil microorganisms in the treatments with pH regulators were promoter than CK during the initial 30 days; while the results from the 90 days indicated that the activity and the carbon source utilization of soil microbes in acid regulator treatment began to fall down, even lower than that of poplar implant treatment, then the alkaline treatment could still stimulate and promote the activity and the carbon source utilization ability of soil microbes. Overall, the activity and community structure of soil microbes in rhizo- sphere zones of atrazine-contaminated soil did not show steady regularity during the phytoremediation process by using hybrid poplars. For the reason that the Biolog E- CO plate, which only had 31 kinds of carbon sources, could not really indicate the detail information about the function diversity of community structure of soil mi- crobes. So it＇s essential for us to take more sophisticated analysis tools for further study.

Microstructure and tensile properties of as-extruded Mg-Sn-Y alloys

The microstructure and tensile properties of the Mg-1.0%Sn-xY(x=1.5%,3.0%,3.5%,atom fraction)alloys extruded indirectly at 350℃ were investigated by means of optical microscopy,scanning electron microscopy and tensile test.The mean grain sizes ofα-Mg matrix in the three extruded alloys are 6,8 and 12μm,respectively,slightly increasing with the addition of Y. The relationship between microstructure and strength was discussed in detail.The results show that the addition of Y has little effect on the grain refinement of the as-extruded Mg-Sn based alloys above.The only MgSnY phase is detected in the Mg-Sn-1.5%Y alloy, and the Sn3Y5 phase in the Mg-Sn-3.5%Y alloy,whereas both of them simultaneously exist in the Mg-Sn-3.0%Y alloy.The particle shape of MgSnY and Sn3Y5 phase,inherited from the solidification,has little change before and after hot extrusion.Mg-Sn-3.0%Y alloy has the highest ultimate tensile strength(UTS),305 MPa,by over 50%compared with that of the other two alloys.

Dinophysis caudata generated lipophilic shellfish toxins in bivalves from the Nanji Islands, East China Sea

A 12-month program of monitoring potentially toxic microalgae(that produce lipophilic shellfi sh toxins; LSTs) and their toxins in bivalves was conducted from April 2006 to March 2007 in the Nanji Islands, East China Sea. Two Dinophysis species, D. caudata and D. acuminata, were identifi ed, and D. caudat a was found to be the dominant species. D. caudata was detected in water samples between April and June 2006, and between February and March 2007. It reached its highest abundances in May, with a mean abundance of 1.38×10 2 cells/L in surface water and 1.25×10 2 cells/L in bottom water(<10 m deep). The temporal distribution of D. caudata was associated with the occurrence of LSTs in bivalve samples, which mostly occurred at the same time as D. caudata blooms, between April and July 2006. All of the cultured bivalves sampled between April and June were contaminated with LSTs, with an average toxicity of 85 μg okadaic acid(OA) eq./100 g meat, which was four times higher than the Chinese regulatory limit(20 μg OA eq./100 g meat). Ten out of fi fteen wild samples(66.7%) collected during the same period were positive for LSTs, and contained an average LST toxicity of 45 μg OA eq./100 g meat(more than twice the regulatory value). Cultured Patinopecten yessoensis collected on 15 May 2006 had the highest toxicity, 320 μg OA eq./100 g meat, and relatively high toxicities(80 to 160 μg OA eq./100 g meat) were found in bivalves until the end of July.

Laparoscopic calibrated total vs partial fundoplication following Heller myotomy for oesophageal achalasia

AIM:To compare the mid-term outcomes of laparoscopic calibrated Nissen-Rossetti fundoplication with Dor fundoplication performed after Heller myotomy for oesophageal achalasia.METHODS:Fifty-six patients(26 men,30 women;mean age 42.8±14.7 years)presenting for minimally invasive surgery for oesophageal achalasia,were enrolled.All patients underwent laparoscopic Heller myotomy followed by a 180°anterior partial fundoplication in 30 cases(group 1)and calibrated NissenRossetti fundoplication in 26(group 2).Intraoperative endoscopy and manometry were used to calibrate the myotomy and fundoplication.A 6-mo follow-up period with symptomatic evaluation and barium swallow was undertaken.One and two years after surgery,the patients underwent symptom questionnaires,endoscopy,oesophageal manometry and 24 h oesophago-gastric pH monitoring.RESULTS:At the 2-year follow-up,no significant difference in the median symptom score was observed between the 2 groups(P=0.66;Mann-WhitneyU-test).The median percentage time with oesophageal pH< 4 was significantly higher in the Dor group compared to the Nissen-Rossetti group(2;range 0.8-10 vs 0.35;range 0-2)(P<0.0001;Mann-WhitneyU-test).CONCLUSION:Laparoscopic Dor and calibrated Nissen-Rossetti fundoplication achieved similar results in the resolution of dysphagia.Nissen-Rossetti fundoplication seems to be more effective in suppressing oesophageal acid exposure.

EVOLUTION OF LIQUID WATER CONTENT IN A SEA FOG CONTROLLED BY A HIGH-PRESSURE PATTERN

On March 16–17, 2008, a sea fog occurred in Dianbai in the west of Guangdong Province and was accompanied by a high-pressure synoptic system. Using comprehensive observation datasets, this study analyzes the evolution of liquid water content during this sea fog and investigates the relationships between liquid water content and the average diameters and count densities of fog droplets, air temperature, wind speed and turbulence exchanges. The main results are presented as follows. (1) The sea fog showed a quasi-periodic oscillation characteristic, i.e., it developed, disappeared and then developed again. (2) During the sea fog, the number of fog droplets changed significantly while the changes in average diameter of the fog droplets were relatively small. The development and disappearance of the sea fog correlated significantly with the fog droplet numbers. (3) The air-cooling mechanism played a significant role in sea fog formation and development. However, the influences of this mechanism were not evident during fog persistence. (4) During sea fog formation, weak turbulence exchanges were helpful for fog formation. During sea fog development and persistence, liquid water content increased when turbulence exchanges weakened, and vice versa. The changes in turbulence exchanges were closely related to the quasi-periodic oscillations observed in sea fog presence.

Microstructure and tensile properties of AM50A magnesium alloy prepared by recrystallisation and partial melting process

Prior to thixoextrusion, the microstructural evolution of semi-solid AM50A magnesium alloy prepared by the recrystallisation and partial remelting (RAP) route was investigated.The effect of compressive ratio on microstructure of semi-solid AM50A magnesium alloy was studied.Furthermore, tensile properties of thixoextruded components were determined.The results showed that the occurrence of recrystallised grains was closely associated with the location of the first liquid formed above the solidus.With prolonging holding time, deformed microstructure was penetrated, causing fragmentation, which resulted in the decrease of average grain size.Moreover, prolonging holding time was favorable for the improvement of the degree of spheroidization due to the increase in the amount of liquid.With the increase in compressive ratio, the size of solid grain decreased, the degree of spheroidization was improved during partial remelting, and the tensile properties of thixoextruded AM50A components were improved.The tensile properties for AM50A magnesium alloy thixoextruded from starting material produced by the RAP route were better than those of the same alloy produced by die-casting and thixomolding.

机床地脚低速滑动界面法向刚度分形模型及试验验证

按照一个弹性微凸体的平均接触压强构筑微凸体顶端接触变形。计及动摩擦因数计算微凸体最初屈服的临界平均压强。采用以无阻尼自然角频率为自变量的功率谱密度函数,给出识别界面分形维数、特征长度的理论和试验方法。仿真结果表明:微凸体最初屈服的临界平均压强随着动摩擦因数的增加而变小;分形区域扩展因数随着分形维数的增加而减小;微凸体最大结合面积随着分形维数的增加呈现线性减小;增加动摩擦因数、面积比和特征长度都将衰减法向接触刚度;法向接触刚度随着分形维数、接触面积的比率、法向接触载荷或微凸体最大结合面积的增加而增强。按照有限元模拟对界面法向接触参数识别结果进行证明。考虑界面参数的有限元模型得到的动柔度、法向接触刚度数据与试验数据一致。

Synthesis and characterization of MgSO_4·5Mg(OH)_2·2H_2O flake powders

Magnesium oxysulfate （MgSO4·5Mg（OH）2·2H2O） flake powders with an average diameter of 2 ~tm and a thickness of 0.052 μm were prepared using magnesium sulfate and sodium hydroxide as raw materials by hydrothermal synthesis process. The composition, morphology and structural features of the hydrothermal products were examined with X-ray powder diffraction （XRD）, scanning electron microscopy （SEM） and Fourier transform infrared spectroscopy （FTIR）. The experimental results indicate that in the conditions of n（NaOH）/n（MgSO4） of 1.25, the dosage of w（Na3PO4） crystal additives of 1.0% w（MgSO4）, stirring for 5 h at 180 ℃, the morphology of MgSO4·5Mg（OH）2·2H2O products is flaky and laminar, which is a kind of complex magnesium singlecrystal. The recycling of MgSO4 mother liquor was also investigated to make a full use of the materials and reduce disposal. The results prove that there is no adverse effect on the yield and purity of the products.

Effect of Biodiesel Soot on Tribological Behavior of Liquid Paraffin

Biodiesel soot （BDS） was collected from the combustion of biodiesel using a self-made soot trap. The effect of BDS on the txibological behavior of liquid paraffin （LP） was investigated using a four-ball txibometer. A rotating viscometer was used to investigate the effect of BDS on the viscosity of LE The morphology, composition, and tribological mechanism of BDS were studied by means of FETEM, XRD, XPS, SEM/EDS, and the 3D laser scanning microscopy. Test results showed that the BDS aggregates were chain-like, and the average diameter of BDS was 35 nm. The BDS existed in the form of graphitic layers and amorphous carbon. The oxygen-containing functional groups in BDS consisted of the （C-O-C） and （C-O-H）. With an increasing BDS content, the dynamic viscosity of LP increased and the maximum non-seizure load increased initially and became stable later. In addition, the average wear scar diameter （AWSD） of LP increased and the average friction coefficient of LP decreased at first and then increased later. The tribological mechanisms could be ascribed to the variation in content of BDS： BDS could act as a friction modifier for a lower friction coefficient in case of low BDS content. However, the BDS aggregates could lead to increase of abrasive wear to influence the lubricating oil film at higher content of BDS, which would reduce the friction reduction ability and wear resistance of LP.

Effects of ambient DIN:DIP ratio on the nitrogen uptake of harmful dinoflagellate Prorocentrum minimum and Prorocentrum donghaiense in turbidistat

The effects of varying nitrogen （N）： phosphorus （P） ratios on the growth and N-uptake and assimilation of the harmful dinoflagellates Prorocentrum minimum and Prorocentrum donghaiense were examined in turbidistat culture experiments. Algal cultures were supplied with media containing PO4^3- in various concentrations to obtain a wide range of N：P ratios. Experiments to determine rates of N uptake and assimilation of different N sources （NO^3-, NH4^＋, urea and glycine by P. minimum and NO3^-, NH4^＋ by P. donghaiense） were conducted using ^15-N tracer techniques at each N：P ratio. The growth rates suggested nutrient limitation at both high and low N：P ratios relative to the Redfield ratio. On a diel basis, the growth of both species was regulated by the light-dark cycle, which may be a result of regulation of both lightdependent growth and light-independent nutrient uptake. Maximum growth rates of both species always occurred at the beginning of light phase. In P-rich medium （low N：P ratio）, both species had higher N assimilation rates, suggesting N limitation. Low assimilation coefficients at high N：P ratios suggested P limitation of N uptake and assimilation. NO3 ^-and NH4^＋ contributed more than 90% of the total N uptake of P. minimum. Reduced N sources were more quickly assimilated than NO3^-. Highest average daily growth rates were recorded near an N：P ratio of 12 for both species. The N uptake rates of cultures at N：P ratios near Redfield ratio were more balanced with growth rates. The linkage between growth rates and N uptake/assimilation rates were conceptually described by the variation of cell N quota. The N：P ratios affect the N uptake and growth of Prorocentrum spp., and may regulate their bloom progression in eutrophic ecosystems.

Stochastic Huge-Resonance Caused by Coupling for a Globally Coupled Linear System

In the paper, we investigate a globally coupled linear system with finite subunits subject to temporal periodic force and with multiplicative dichotomous noise. It is shown that, the global coupling among the subunits can hugely enhance the phenomenon of SR for the amplitude of the average mean field as the functions of the transition rate of the noise and that as the function of the frequency of the signal respectively.

Effect of sintering atmosphere on composition and properties of NiFe_2O_4 ceramic

Ni Fe2O4 ceramics were prepared in different sintering atmospheres. The phase compositions, microstructures and mechanical properties were studied. The results show that the stoichiometric compound Ni Fe2O4 cannot be obtained in vacuum or atmospheres with oxygen contents of 2×10-5, 2×10-4 and 2×10-3, respectively. All the samples sintered in above-mentioned atmospheres contain phases of Ni Fe2O4 and Ni O. With increasing oxygen content, Ni Fe2O4 content in the ceramic increases, while Ni O content appears a contrary trend. In vacuum, Ni Fe2O4 ceramic has average grain size of 3.94 μm, and bending strength of85.12 MPa. The changes of the phase composition and mechanical properties of Ni Fe2O4 based cermets are mainly caused by the alteration of their properties of Ni Fe2O4 ceramic.

Microsatellite DNA polymorphisms and the relation with body weight in sea cucumber Apostichopus japonicus

The relationship between microsatellite polymorphism and body weight of captive bred Chinese sea cucumber Apostichopus japonicus was investigated in two local populations in Dalian. Among ten loci discovered, nine show changes except for AJ07 loci. Seven loci were found highly polymorphic in both populations. For each locus in two populations, the average number of alleles is 6.428 6 and 6.285 7, the average observed heterozygosity at 0.225 7 and 0.245 9, the expected heterozygosity at 0.776 8 and 0.748 8, the polymorphism information content (PIC) at 0.709 2 and 0.674 6, respectively. Further analysis show significant correlation between A. japonicus body weight and occurrence markers AJ02 and AJ04. The findings of the relation may be helpful for molecular breeding, as well as the marker-assisted selection of sea cucumbers.

Carotenoids Particle Formation by Supercritical Fluid Technologies

Based on the solubility in supercritical CO2,two strategies in which CO2 plays different roles are used to make quercetine and astaxanthin particles by supercritical fluid technologies.The experimental results showed that micronized quercetine particles with mean particle size of 1.0-1.5 μm can be made via solution enhanced dispersion by supercritical fluids(SEDS) process,in which CO2 worked as turbulent anti-solvent;while for astaxanthin,micronized particles with mean particle size of 0.3-0.8 μm were also made successfully by rapid expansion supercritical solution(RESS) process.