关于松花湖鱼类增殖问题的调查与思考

松花湖是吉林省最大的人工水域和渔业水域,"三花一岛"久负盛名。多年来,由于自然环境变迁,水域污染,投入不足,过度捕捞,管理不善等诸多因素影响,鱼类资源持续衰退。除施氏鲟等名贵鱼类早已绝迹外,另一些土著名优品种如"三花一岛"等也濒临绝迹,不能满足居民对鱼类产品的优质化、多样化需求,供求矛盾十分突出。因此有必要通过清理拦网、整合资源;加大投入,恢复资源;科学养殖,开发资源;强化管理,保护资源,再现松花湖渔业的辉煌。     

小波域声呐图像自适应增强

声呐图像受噪声污染严重、对比度低,给后期的定位识别带来不便,而传统的处理方法容易造成边缘模糊.针对这一问题,提出了一种图像自适应增强算法.该算法利用形态小波对声呐图像进行自适应的多分辨率分析,分别增强不同尺度上的信号或细节,通过多通道重构图像的加权实现去噪和对比度提高.仿真结果表明该算法快速有效,对高斯噪声和冲击性噪声都具有较好的鲁棒性,处理后的声呐图像边缘细节信息保留完好,得到了理想的增强效果.     

一种面向跨项目软件缺陷预测的特征过滤与实例迁移框架

在跨项目软件缺陷预测中,源项目与目标项目的特征关联度与实例分布差异性是影响预测模型性能的主要因素。本文从特征过滤与实例迁移2个角度出发,提出一种跨项目软件缺陷预测框架KCF-KMM(K-medoids Cluster Filtering- Kernel Mean Matching)。在特征过滤阶段,该方法基于K-medoids聚类算法来筛选特征子集,过滤与目标项目关联度低的特征。在实例迁移阶段,通过KMM算法计算源项目与目标项目实例间的分布差异度,以此分配每个训练实例的影响权重。最后,结合目标项目中少量有标注数据建立混合缺陷预测模型。为了验证KCF-KMM的有效性,本文从准确率和F1值的角度出发,分别与经典的跨项目软件缺陷预测方法TCA+、TNB和NNFilter相比,KCF-KMM的预测性能在Apache数据集上可以分别提升34.1%、0.8%、21.1%和14.4%、3.7%、10.6%。     

Study of speech enhancement in the background of ship-radiated noise

Spectral subtraction is wildly used in speech enhancement. But it is not always available in the ship working environment because of the fact that it is hard to discriminate the speech duration with the ship noise. So, in this paper, we propose a new approach, which first computes the frequency spectrum similarity and then discriminates the signal segments into speech or noise roughly. And then by the frame shifting method, we achieve a high discrimination precision. Finally, the improved algorithm is benchmarked on a large measured data and experimental results show that the proposed method can be used in various ship-radiated noise environments. The discrimination accuracy is 98％ for ship-radiated noise and 96％ for speech.     

纳米流体在内置扭带管的传热数值模拟

为了对比纳米流体在内置扭带管中的强化传热效果,建立了以Cu-水纳米流体和水为传热介质的内置扭带强化换热管的管式换热器物理模型,采用RNG k-ε进行数值模拟研究,并与实验结果对比,得到了内置扭带换热管流体流动的速度、温度、湍流强度场的分布规律及特性。比较了两种质量分数的纳米流体与水在六种不同扭转比的扭带换热管中和两种不同材质的内置扭带分别对强化传热的影响。结果表明,以Cu-水纳米流体为工质的内置扭带管的换热效果明显优于纯水;质量分数为0.8%的Cu-水纳米流体换热效果优于0.5%的Cu-水纳米流体,扭转比越小,则换热效果越好,质量分数为0.5%的Cu-水纳米流体在扭转比为2.5的内置扭带管中相对于水在光管的强化幅度为0.51;铜制扭带的换热效果优于铝制扭带。     

Comparative analysis of different methods for image enhancement

Image enhancement technology plays a very important role to improve image quality in image processing. By enhancing some information and restraining other information selectively, it can improve image visual effect. The objective of this work is to implement the image enhancement to gray scale images using different techniques. After the fundamental methods of image enhancement processing are demonstrated, image enhancement algorithms based on space and frequency domains are systematically investigated and compared. The advantage and defect of the above-mentioned algorithms are analyzed. The algorithms of wavelet based image enhancement are also deduced and generalized. Wavelet transform modulus maxima（WTMM） is a method for detecting the fractal dimension of a signal, it is well used for image enhancement. The image techniques are compared by using the mean（μ）,standard deviation（？）, mean square error（MSE） and PSNR（peak signal to noise ratio）. A group of experimental results demonstrate that the image enhancement algorithm based on wavelet transform is effective for image de-noising and enhancement. Wavelet transform modulus maxima method is one of the best methods for image enhancement.     

Fluorescence enhancement and cofluorescence in complexes of terbium(III) with trimellitic acid

1. Introduction Rare earth elements have an important function inlife process. The fluorescence enhancement of lan-thanides in aqueous solutions has therefore becomean area of active study in trace-level estimation oflanthanides using spectrofluorimetry [1]. Its possiblemechanism and application as fluorescence probesin biological systems have also attracted attention inrecent years [2]. Generally, fluorescence enhance-ment can be achieved through ligand sensitization.Various ligands have bee…     

Fluorescence enhancement and cofluorescence in complexes of terbium(Ⅲ) with trimellitic acid

The fluorescence of terbium (Ⅲ) was enhanced by about three orders of magnitude in the presence of trimellitic acid (benzene-l, 2, 4-tricarboxylic acid (TLA)) in aqueous solution at pH 6. The fluorescence intensity could be greatly increased when the system of Tb3+-TLA was treated with La3+ (or Gd3+) and TritonX- 100. The addition of La3+ (or Gd3+) enhances the fluorescence of the system by about two orders of magnitude due to cofluorescence, and the TritonX-100 micellar medium plays an important role for stabilization of the system. Both the intermolecular energy transfer mode and intramolecular energy transfer mode are responsible for the mechanism of fluorescence enhancement. In the optimum conditions, the fluorescence intensity is a linear function of Tb3+ concentration in the range of 7.8 × 10-9-3.6 × 10-6 mol/L for the system Tb3+-La3+-TLA and 1.0 × 10-8-4.7 × 10-6 mol/L for the system Tb3+-Gd3+-TLA, and the limits of detection are 4.6 ×10-10 mol/L and 6.0 × 10-10 mol/L, respectively.     

面状缺陷超声B扫描检测图像增强研究

针对面状焊接缺陷超声B扫描检测图像受噪声污染造成的质量下降问题,利用多尺度小波分析方法,对超声B扫描图像进行了增强处理.分析了缺陷信号和噪声的小波变换特性,分别在软、硬阈值函数条件下,采用固定阈值、Stein无偏似然估计阈值、混合型阈值、极大极小准则阈值等方法进行了信号增强处理,比较了不同阈值方法小波变换的处理效果.结果表明:小波变换方法能有效地提高超声B扫描图像质量,硬阈值条件下固定阈值小波变换方法的图像增强处理效果较好.     

Simulations of the dielectric constant of bonding materials and field emission properties of CNT cathodes

The effect of the dielectric constant (k) of bonding materials in a screen-printed carbon nanotube (CNT) cathode on the field enhancement factor was investigated for high-efficiency CNT cathodes using the ANSYS software. The values obtained by a simulation study were compared to the experimental results obtained for screen-printed CNT cathodes. The field enhancement factor increased as the dielectric constant decreased, reaching a maximum value at a dielectric constant of 1, the value for a vacuum. The findings indicate that the larger sheet resistance of the bonding materials, after the firing process, can be attributed to the larger emission current of the CNT cathode. From these results, it was concluded that the best bonding materials for screen-printed CNT cathodes should have a low dielectric constant and a high sheet resistance. This finding can be used as criteria for selecting bonding materials for use in CNT pastes for highly efficient CNT cathodes.