基于动态特性的D-LTSV语音端点检测方法

端点检测是语音信号处理的一个关键环节。为提高语音在低性噪比以及非平稳噪声环境下的端点检测性能,在长时信号变化特征(LTSV)的基础上提出一种新的D-LTSV语音端点检测方法。采用Bartlett-Welch方法估计语音谱,分析语音谱在长时域上的熵,利用倒谱的动态特性分析方法提取连续帧熵值的动态变化特征。实验结果表明,D-LTSV综合考虑了语音的非平稳性和帧间非平稳性的动态变化情况,具有比LTSV更好的分辨能力,特别是在低性噪比和非平稳噪声的环境下,D-LTSV的分辨能力提升了50.77%,能够准确地进行端点检测,具有更强的鲁棒性。     

一种低功耗的社区机会网络消息路由算法

社区机会网络中节点的移动具有一定的相关性且不同的节点往往具有不同的移动特点,当前机会网络中主流的多拷贝路由算法并未充分考虑到这些特点,将该算法直接应用于这类网络会导致资源消耗较高、传输成功率低等问题。针对这些问题,提出一种基于社区的低功耗消息路由算法,其能自适应地控制消息拷贝数量,并根据节点与目标社区节点和本地社区节点相遇的历史信息来设置其目标社区和本地社区的活跃度,依靠活跃度较高的节点来完成消息传输。仿真结果表明,在延迟要求比较宽松的社区机会网络中,该算法在消息传输的成功率及占能耗最主要部分的消息转发次数方面明显优于Spray and Focus算法。     

Study of Ozonated Sunflower Oil Using 1H NMR and Microbiological Analysis

Prior studies have proven that ozonated vegetable oils present a high germicidal power. Ozonation of sunflower oil at different applied ozone dosage was carried out and peroxide and aldehydes indices along with antimicrobial activity were determined. The reaction products were identified using Proton Nuclear Magnetic Resonance Spectroscopy (¹H NMR). The principal signals intensity values were used for following the reaction course between ozone and sunflower oil. The reaction was following up to peroxide index values of 1202 mmol-equi/kg. The intensities of olefinic proton signals decreased with the gradual increase in ozone concentration but without disappearing completely. The Criegee ozonides obtained at 107.1 mg/g of ozone doses were approximately 3.9-fold higher than that at beginning of the reaction. The aldehyde protons were observed as a weak intensity signal in all the spectra. The signals belonging to olefinic protons from hydroperoxides appeared weak and increased with the increase in ozone doses. Signals from other oxygenated groups were assigned. The highest action spectrum of antimicrobial activity was obtained with the higher peroxide index. It was concluded that at higher applied ozone doses, the higher the antimicrobial activity potential of ozonized sunflower oil     

电解质溶液热力学性质的研究进展

从电解质溶液的经典理论、半经验模型和统计力学3方面综述了电解质溶液热力学性质的研究进展,并对各种理论和模型在理论与实践方面的局限性作了相关评述。从分子、离子角度对电解质溶液的热力学性质进行研究比较,探讨了其宏观热力学性质与微观结构的相关性。展望了电解质溶液热力学理论近期研究的热点和未来的发展方向。     

Ethanol electrooxidation on novel carbon supported Pt/SnOx/C catalysts with varied Pt:Sn ratio

Novel carbon supported Pt/SnO_x/C catalysts with Pt:Sn atomic ratios of 5:5, 6:4, 7:3 and 8:2 were prepared by a modified polyol method and characterized with respect to their structural properties (X-ray diffraction (XRD) and transmission electron microscopy (TEM)), chemical composition (XPS), their electrochemical properties (base voltammetry, CO_ad stripping) and their electrocatalytic activity and selectivity for ethanol oxidation (ethanol oxidation reaction (EOR)). The data show that the Pt/SnO_x/C catalysts are composed of Pt and tin oxide nanoparticles with an average Pt particle diameter of about 2 nm. The steady-state activity of the Pt/SnO_x/C catalysts towards the EOR decreases with tin content at room temperature, but increases at 80 °C. On all Pt/SnO_x/C catalysts, acetic acid and acetaldehyde represent dominant products, CO₂ formation contributes 1-3% for both potentiostatic and potentiodynamic reaction conditions. With increasing potential, the acetaldehyde yield decreases and the acetic acid yield increases. The apparent activation energies of the EOR increase with tin content (19-29 kJ mol⁻¹), but are lower than on Pt/C (32 kJ mol⁻¹). The somewhat better performance of the Pt/SnO_x/C catalysts compared to alloyed PtSn_x/C catalysts is attributed to the presence of both sufficiently large Pt ensembles for ethanol dehydrogenation and C-C bond splitting and of tin oxide for OH generation. Fuel cell measurements performed for comparison largely confirm the results obtained in model studies.     

硝酸硫胺活度积常数的测定

采用激光测量了不同溶液条件下硝酸硫胺的溶解度，进一步确定了硝酸硫胺的活度积常数。硫酸硫胺的活度积常数对于控制硝酸硫胺生产过程、研究结晶过程动力学、提高产品收率具有重要的理论指导意义。     

浅谈合唱活动对校园精神文化建设的促进作用

合唱活动是校园里最活跃、最具广泛群众基础的校园文化活动表现形式之一。合唱活动有助于校风建设,特别是能培育师生的集体主义情感和增进师生友谊;合唱活动有助于教风建设,特别是能加强教师师德修养,促使教师更加敬业;合唱活动有助于学风建设,特别是能促进学生明确学习目的,激发学生的爱国热情和学习热情,还能提高学生的综合能力。     

Co3O4对RuO2—TiO2（60）／Ti阳极析氯活性和欧姆降的影响

用稳态恒电流法和断电流技术研究了Co_3O_4对RuO_2-TiO_2(60)/Ti阳极析氯催化活性和欧姆降的影响。适量Co_3O_4可以大大提高RuO_2-TiO_2(60)/Ti阳极的析氯催化活性,明显减小涂层欧姆降。RuO_2(40)-TiO_2(60)/Ti阳极涂层中近65％的RuO_2被Co_3O_4取代后,电极析氯速率不会下降。     

铂类抗癌配合物构效关系的理论探讨

基于铂抗癌配合物在体内的历程和化学反应探讨了它们的结构和活性之间的关系，获得决定抗癌活性大小的主要因素，包括配合物分子的脂溶性和空间体积、构型、离去基团的反应性以及载体基团的特性。提出了铂配合物具有较高抗癌活性的结构要求①非离子型②小的空间体积③顺式构型④含脂溶性的氨（胺）载体和以Ｃｌ￣（－）或二元羧酸作离去基团。     

Moodle平台在高职院校信息化教学中的设计与应用

本文主要从Moodle平台的特点以及高职院校信息化教学中存在的问题展开,在做了详细的需求分析的前提下,对教学方案的实施效果和存在的问题进行了分析和总结,指出必须确立＂教育的最终结果,就是培养一个独立的学习者＂的目标,同时加强师生互动交流和自主学习能力建设,才能构建科学合理的符合网络教学规律的教学方案。