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41.
Alexander I. Iliev Michael S. Scordilis João P. Papa Alexandre X. Falcão 《Computer Speech and Language》2010,24(3):445-460
A new method for the recognition of spoken emotions is presented based on features of the glottal airflow signal. Its effectiveness is tested on the new optimum path classifier (OPF) as well as on six other previously established classification methods that included the Gaussian mixture model (GMM), support vector machine (SVM), artificial neural networks – multi layer perceptron (ANN-MLP), k-nearest neighbor rule (k-NN), Bayesian classifier (BC) and the C4.5 decision tree. The speech database used in this work was collected in an anechoic environment with ten speakers (5 M and 5 F) each speaking ten sentences in four different emotions: Happy, Angry, Sad, and Neutral. The glottal waveform was extracted from fluent speech via inverse filtering. The investigated features included the glottal symmetry and MFCC vectors of various lengths both for the glottal and the corresponding speech signal. Experimental results indicate that best performance is obtained for the glottal-only features with SVM and OPF generally providing the highest recognition rates, while for GMM or the combination of glottal and speech features performance was relatively inferior. For this text dependent, multi speaker task the top performing classifiers achieved perfect recognition rates for the case of 6th order glottal MFCCs. 相似文献
42.
Recent work has shown that trehalose can facilitate and inhibit protein folding, but little is known about the molecular basis of these effects. Molecular-level insights into how the osmolyte affects protein folding are of significance for the rational design of small molecular additives for enhancing or hindering the folding of proteins. To investigate the molecular mechanisms of the facilitation and inhibition effects of trehalose on protein folding, molecular dynamics (MD) simulation of a beta-hairpin peptide (Trp-Arg-Tyr-Tyr-Glu-Ser-Ser-Leu-Glu-Pro-Glu-Pro-Asp) in different trehalose concentrations (0-0.26 mol/L) is performed using an all-atom model. It is found that at a proper trehalose concentration (0.065 mol/L), the peptide folds faster than that in water, but it cannot fold to the beta-hairpin at higher trehalose concentrations. Free energy landscape analysis indicates the presence of three intermediate states in both pure water and in 0.065 mol/L trehalose, but the potential energy barriers in the folding pathway decrease greatly in 0.065 mol/L trehalose, so the peptide folding is facilitated. Moreover, at this trehalose concentration, there is a favorable balance between the peptide backbone hydrogen bonds (H-bonds) and the peptide-trehalose H-bonds, leading to the stabilization of the folded peptide. At higher trehalose concentrations, however, trehalose molecules cluster in the peptide region and interact with the peptide via many H-bonds that prevent the peptide from folding to its native structure. The energy landscape analysis indicates that the potential energy barriers increase so greatly that the peptide cannot overcome it, getting trapped in a local free energy basin. The work reported herein has elucidated the molecular mechanism of the peptide folding in the presence of trehalose. 相似文献
43.
A weight function-critical plane approach for low-cycle fatigue under variable amplitude multiaxial loading 总被引:1,自引:0,他引:1
X. CHEN D. JIN K. S. KIM 《Fatigue & Fracture of Engineering Materials & Structures》2006,29(4):331-339
Low‐cycle fatigue data of type 304 stainless steel obtained under axial‐torsional loading of variable amplitudes are analyzed using four multiaxial fatigue parameters: SWT, KBM, FS and LKN. Rainflow cycle counting and Morrow's plastic work interaction rule are used to calculate fatigue damage. The performance of a fatigue model is dependent on the fatigue parameter, the critical plane and the damage accumulation rule employed in the model. The conservatism and non‐conservatism of predicted lives are examined for some combinations of these variables. A new critical plane called the weight function‐critical plane is introduced for variable amplitude loading. This approach is found to improve the KBM‐based life predictions. 相似文献
44.
采用十字流微滤方法分离莲子心醇提液中的莲心碱和叶绿素,考察了不同操作条件下微滤过程中各种过滤阻力的大小及其构成情况,分析了影响莲心碱和叶绿素微滤的主要因素,并提出降低膜污染、提高膜过滤速率的改进措施. 相似文献
45.
46.
A silica-supported cobalt catalyst was prepared by hydrogen dielectric-barrier dis- charge (H2-DBD) plasma. Compared to thermal hydrogen reduction, H2-DBD plasma treatment can not only fully decompose the cobalt precursor but also partially reduce the cobalt oxides at lower temperature and with less time. The effect of the discharge atmosphere on the property of the plasma-prepared catalyst and the Fischer-Tropsch synthesis activity was studied. The re- sults indicate that H2-DBD plasma treatment is a promising alternative for preparing Co/SiO2 catalysts from the viewpoint of energy savings and efficiency. 相似文献
47.
为研究氨水改性对具有MFI结构的Silicalite-1分子筛催化环己酮肟气相Beckmann重排反应性能的影响,选用两种水热合成工艺合成了单斜和正交两种晶系的Silicalite-1分子筛,并用氨水分别对其进行改性处理。通过XRD和IR表征考察了不同合成方法、不同的处理温度、时间等因素对催化剂晶体结构、表面硅羟基的影响。表征结果说明氨水处理时间和温度可能会改变分子筛的晶系、表面硅羟基的强度和种类。改性前后Silicalite-1催化Beckmann重排反应评价的结果说明重排反应的主活性中心是硅羟基窝,但活性中心和MFI结构的晶系没有关系。碱处理能够减弱副反应活性中心末端硅羟基,提高催化剂的稳定性和产物己内酰胺的选择性。 相似文献
48.
Yan-Bing ZhuWei Wang 《Thin solid films》2012,520(7):2474-2478
P-type Bi-Sb-Te-Se thermoelectric thin films with thickness of 8 μm have been prepared by cathodic electrodeposition technique on Au substrate from nitric acid solution system at room temperature. Cyclic voltammetry was used for determination of the deposition potentials of the thin films. In order to enhance the crystallinity, as well as the thermoelectric properties of the deposited films, they were annealed at 523 K for 2 h under nitrogen atmospheric pressure condition. X-ray diffraction (XRD), environmental scanning electron microscopy, and energy-dispersive spectroscopy (EDS) were employed to characterize the thin films. Seebeck coefficients and resistivities of the films were also evaluated. The results revealed that Bi, Sb, Te and Se could be co-deposited to form Bi-Sb-Te-Se semiconductor compound in the solution containing BiIII, SbIII, TeIV and SeIV and the compositions of the films were sensitive to the electrodepositing potentials. The XRD results suggested that the crystal structure of the thin films were changed from amorphous state to polycrystalline after annealing. The EDS data indicated that the composition of the films was consistent with XRD results. The annealed Bi-Sb-Te-Se thin films exhibited the Seebeck coefficients of 116-133 μV/K and a maximum power factor of 0.62 mW·K− 2·m− 1. 相似文献
49.
The paper concerns the removal of ammonium ions from aqueous solution using a modified clinoptilolite-Ca(2+)-formed clinoptilolite (CaY) prepared from natural clinoptilolite. The batch study results show that the pH has an effect on ammonium adsorption capacity as it can influence both the character of the exchanging ions and the clinoptilolite itself; the CaY has a high selectivity to NH(4)(+) and the exchange decreases with increasing temperature; ammonium ion uptake onto CaY was suitably described by the Langmuir model. The column results indicated that the effluent of simulated wastewater treated with CaY could meet the integrated wastewater discharge standard of China, and CaY can be circulated through regenerating by Ca(OH)(2). 相似文献
50.
《Applied catalysis》1987,29(2):193-201
Mercury in very low concentrations (i.e. when there is up to about one Hg atom in one hundred Pt atoms) promotes the dehydrogenation activity of supported Pt towards cyclohexane and to a lesser extent cyclohexene. However, dehydrochlorination activity towards monochlorocyclohexane is relatively unaffected by Hg additions. Interestingly, cyclohexene is a significant intermediate from dehydrochlorination at high Hg concentrations; consideration is given to reaction mechanisms. The low concentrations at which Hg promotes catalytic activity suggests that it may disrupt the lattices of the Pt crystallites producing surface sites of low coordination and high activity. 相似文献