铝基波纹表面结霜特性实验研究

本文针对铝基波纹翅片换热器广泛应用及结霜问题,基于相变驱动力分析结霜机理,实验研究了在不同冷表面温度(-5～-15℃)、空气温度(11～17℃)、空气流速(1.5～2.5 m/s)等工况下,铝基裸铝波纹表面的结霜情况,观察了铝基波纹表面上霜层生长过程中的微观形貌,并采用田口实验法分析了环境因素对表面结霜情况的影响。结果表明：环境因素的改变会对铝基波纹表面结霜产生不同程度的影响,以波纹角度11.3°为例,结霜60 min时,与冷表面温度为-5℃相比,冷表面温度为-10℃和-15℃时结霜量分别增长12.20%和31.28%,霜层厚度分别增长19.95%和47.24%。田口实验法分析表明：相比湿空气温度和空气流速,冷表面温度和湿空气相对湿度对波纹表面结霜特性影响相对较大,对波纹表面结霜量的贡献率分别为37.3%和31.8%,对霜层厚度的贡献率分别为61.1%和22.6%。空气流速对结霜量的贡献率为22.6%,而对结霜层厚度的贡献率仅为4.2%,表明空气流速对霜层的致密化作用较大。     

Mixed convection of a nanofluid past an inclined wavy surface in the presence of gyrotactic microorganisms

The mixed convection of a nanofluid flow past an inclined wavy surface in the existence of gyrotactic microbes is considered. To convert the wavy surface to a plane surface, a transformation of coordinates is applied. The governing equations that are nonlinear and the accompanying boundary conditions are converted into a dimensionless form using pseudo-similarity variables. Using a local linearization process, the system of nonlinear partial differential equations is linearized. The resulting system is solved using the Bivariate Chebyshev pseudo-spectral collocation method. The influence of different physical and geometrical factors on the parameters of engineering importance of the flow is analyzed and illustrated graphically. It is observed that the skin friction, the density of motile microorganisms, and nanoparticle mass transfer rate are increasing with an increase in the bioconvection Peclet and Schmidt numbers whereas these quantities are decreasing with an increase in Rayleigh number. The local Nusselt number, nanoparticle Sherwood number, and density number of microbes increases with an increase in the Brownian motion and thermophoresis parameter. These physical quantities are increasing when the surface changes from horizontal to vertical.     

A novel two-band equilateral wavelet filter bank method for an automated detection of seizure from EEG signals

One can determinate the occurrence of epileptic seizure from the electroencephalogram (EEG) signal. Nonautomatic epilepsy detection is onerous and may be prone to error. They have augmented automated detection of seizure methods to attain accurate results. In view of this research work, we designed a frequency localized optimal filter bank to assess their effectiveness for automatic detection of seizures from EEG records. The basic preferred requirement of optimal filters relies on low bandwidth in the discipline of biomedical signal processing. This work provides a novel filter bank method called optimal equilateral wavelet filter bank (OEWFB) to satisfy the regularity criteria. This regularity constraint is being satisfied with semi-definite programming (SDP) framework, which specifically does nothing with any parameterization. Implementing the proposed filter banks, it disbands EEG signals into five wavelet sub-bands. The fuzzy entropy (FuEn), Renyi's entropy (ReEn), and the Kraskov entropy (KrEn) are being used for extracting the features from the wavelet sub-bands. The P values provide the distinctive ability of the features. Classification with 10-fold cross-validation for several classifiers such as quadratic discriminant, linear quadratic discriminant, K-nearest neighbor, support vector machine, logistic regression, and complex tree is utilized to classify the EEG signals into seizure vs non-seizure class and seizure-free vs seizure affected class. The proposed research work has gained the highest accuracy, specificity, sensitivity, and positive predictive values of 99.4%, 99%, 99.66%, and 99.35%, respectively, for class-1 (ABCD vs E). The performances of the proposed work using the Bonn EEG data set ensure validation concerning compatibility and robustness.     

The Computational Analysis of Protein Structures: Sources,Methods, Systems and Results

Computational molecular biology is a relatively new specialty that has arisen in response to the very large amount and quality of data currently being produced, including gene and protein sequences (“one-dimensional” information) and nucleic acid and protein structures (“three-dimensional” information). Many important biological investigations can be carried out only through effective computational access to the entire corpus of data. This has stimulated the development of data banks and information retrieval systems. For example, after determination of a new gene sequence, one would like to know whether it is possible to say anything about its structure and function. To try to answer this question one screens the sequence of the corresponding protein for a significant similarity to a protein of known structure. In this article we shall describe the kinds of inferences that are possible if such a relationship is found.     

Heat and mass transfer on the wavy film absorption process

Recently the absorption heat pumps and chillers have received considerable attention due to their low electricity consumption rate. Therefore, it is important to understand the transport mechanism of an absorption process. In this paper, a numerical study of the heat and mass transfer taking place on a wavy falling liquid film of an absorption process is presented. With previously solved periodic wavy film flow solutions, the finite difference method is employed to solve the heat and mass transport equations. The numerical solution indicates that the waves significantly increase the transport rates. A comparison of the transfer rates of the wavy film to that of the smooth film is presented to show that the mass transfer rate can be doubled.     

Wave propagation in a composite with a wavy sublamina

The through-thickness waviness in a sublamina in a composite laminate is the subject of study for the purposes of nondestructive evaluation by ultrasound. The model consists of a flat composite laminate with one sublamina which has sinusoidal waviness. The theoretical analysis of a longitudinal wave propagating through such a laminate is presented and the reflection coefficients at various locations on the plate are calculated. The results are validated by experimental ultrasonic C-scan.     

我国上市银行股利分配影响因素的实证研究

本文以14家上市银行2006年一2012年的面板数据对上市银行的股利分配现状进行了分析,发现我国上市银行的股利分配政策连续性良好,且以现金股利分配为主,而现金股利分配具有一定的稳定性。以同样的数据对上市银行的现金股利分配影响因素进行实证分析,发现盈利水平和累积分配能力对现金股利分配具有正向影响,而负债水平对现金股利分配具有反向影响。盈利水平和累积分配能力越高,上市银行越倾向于分配更多的现金股利;负债水平越高,说明偿债能力越弱,上市银行越倾向于不分配现金股利。研究结果对上市银行的动向分析有积极的意义。     

基于主成分分析法和BP神经网络的银行客户信用评价

为了加强商业银行对客户信用风险的事先控制,降低银行运营风险,需要对客户按信用等级进行分类,以便执行不同的信用风险控制策略。文中基于主成分分析法和BP神经网络法,建立了客户信用评价模型。结果表明,利用此信用风险评价模型能够准确地判断银行客户所处的信用等级,具有广泛的适用性。     

基于子带SDL的宽带抗干扰恒定束宽波束形成

针对宽带恒定束宽波束形成通常需要大量阵元或延迟线所带来的硬件开销较大,并且抗干扰效果较差的问题,提出一种基于子带阵元延迟线(SDL)的宽带抗干扰恒定束宽波束形成算法。该算法通过建立子带SDL模型,利用子带滤波器组将阵元接收信号进行分解与重构,基于约束最小二乘算法进行子带抗干扰恒定束宽波束形成,并将滤波器组的冲击响应直接作为优化参量,可有效降低分解与重构产生的误差。为了衡量阵列响应的波动程度,提出归一化波动程度的概念。仿真结果表明,子带波束形成器具有比全带波束形成器更好的频率不变性和抗干扰能力,而且可以大大降低硬件开销。