Morphology development and phase inversion during dynamic vulcanisation of EPDM/PP blends

Morphology development and phase inversion were investigated during dynamic vulcanisation of ethylene–propylene–diene terpolymer (EPDM)/polypropylene (PP) blends. The effects of viscosity ratio and cross-linking reactions were also addressed. EPDM/PP blends were dynamically vulcanised in a Haake batch mixer using resole and SnCl₂ as cross-linking agents. The morphology development and cross-linking degree with reaction time were followed by morphology analysis (SEM and TEM) and measurement of EPDM gel content, respectively. For the same reaction time, it was found that the EPDM gel content decreased when the low-molecular-weight EPDM was used. As a result, the morphological development was delayed and the phase-inversion point was shifted to higher reaction times, allowing us to monitor morphological development during a thermoplastic vulcanisate (TPV) preparation. Using the low-molecular-weight EPDM and increasing the PP viscosity accelerated the morphological development, shifting phase-inversion to lower reaction times. While blend composition influenced final TPV morphology, it had a minor effect on the mechanism of morphological development. A correlation between cross-linking degree and morphology development was established. The results obtained allowed to propose a mechanism of morphology development during dynamic vulcanisation of the EPDM/PP blends, including phase inversion.     

基于近红外光谱技术的脐橙快速无损检测

以信丰脐橙为对象,研究基于近红外光谱技术的脐橙品质无损检测方法。利用近红外光谱技术采集脐橙的光谱信息,将采集到的光谱信息通过加权平均值的方差处理获得测量结果,然后运用偏最小二乘法建立脐橙内部有机物成分与特征光谱信息之间的耦合关系实现糖度检测。实验结果表明,近红外透射光谱技术可以作为一种准确、可靠、无损的检测方法,用于检测信丰脐橙内部的糖度指标。     

Antioxidant activity,phytochemical screening,and total phenolic content of extracts from three genders of carob tree barks growing in Morocco

We evaluated the in vitro antioxidant property and phytochemical constituents of the crude ethyl acetate and methanol extract of the three genders of carob tree barks (spontaneous male, spontaneous female, and grafted female). The scavenging activity on DPPH (1,1-diphenyl-2-picrylhydrazyl) was determined, as well as the phenolic contents (Folin–Ciocalteu method) of both the extracts. The highest antioxidant activity and the higher amounts of total phenols were shown in methanol crude bark extract for the three genders. Variety significantly affected the phenol content and the antioxidant activity, with the spontaneous male variety globally showed a higher polyphenol concentration and antioxidant activity than the grafted female and spontaneous female.     

Effect of moisture content on conveying characteristics of pulverized coal for pressurized entrained flow gasification

During the pneumatic conveying, pulverized coal with different moisture contents may develop substantial difference in flow characteristics, whose cause is not fully understood. This study focused on influence of moisture content on conveying characteristics in an experimental test facility with the conveying pressure up to 4 MPa. The experiments included soft coal and lignite with similar density and particle size. With the increase in moisture content, the mass flow rate decreased for lignite (3.24% < M < 8.18%) but increased at first and then decreased for soft coal (0.4% < M < 6.18%) at same operating parameters. The flowability of soft coal was worse than that of lignite at similar operating parameters and external moisture content. The extremal conveying moisture contents of two coal types were obtained. The particle charge and surface moisture content were investigated to indicate influence mechanism of moisture content on mass flow rate in pneumatic conveying at high pressure. Pressure drop of soft coal was greater than that of lignite for same test section. The conveying phase diagram of dense-phase pulverized coal at high pressure was obtained and the pressure drops through different test sections were compared and analyzed. The bend loss factor rose with the increase in moisture content and was independent of conveying velocity and solid-gas ratio in dense-phase pneumatic conveying at high pressure.     

Cr_2O_3掺杂对钡硼硅微晶玻璃的性能影响

采用固相合成法制备了高膨胀系数钡硼硅微晶玻璃材料。通过对该微晶玻璃进行X线衍射仪(XRD)、扫描电子显微镜(SEM)测试分析研究铬掺杂对BaO-B2O3-SiO2力、热、电性能及微观机理的影响。结果显示,热膨胀系数与介电损耗随Cr2O3含量增加而增大,研究表明,加入Cr2O3会促进该体系晶粒的生长,并促使晶相由石英晶相转变为方石英晶相,方石英热膨胀系数较高,其晶相含量增多导致热膨胀系数增大。该体系Cr2O3质量分数为0.5%时,制备出具有较高热膨胀系数(18.44×10-6/℃),较高抗弯强度(187 MPa),较低相对介电常数(5.5)的封装材料。     

混合微电路内部水汽含量控制技术

根据气密性封装混合微电路内腔残余气体数据的测试结果,对水汽含量超标的样品进行了深入分析。提出了一种阻断分离法,可用于分析混合微电路水汽失效的原因。采用该方法,对可能引起水汽失效的外壳密封性问题、粘结胶放气问题,以及内部元器件及组装材料放气问题分别进行了试验验证与组合分析,找到了与水汽失效相关的各种原因及控制办法。根据试验分析结果,系统地提出了控制混合微电路内部水汽及其他杂质含量的有效方法。     

全媒体时代广播电视台全媒体业务的探索与实践

随着全媒体技术的发展和媒体受众的改变,广播电视媒体开始拓展全媒体业务,以安庆市广播电视台门户网站及安庆手机台的建设为例,对全媒体内容汇聚管理、多格式多码流集中转码、多屏融合发布以及移动客户端等系统进行了一些探索与实践,从全媒体平台建设构想、建设目标、总体设计以及功能模块详解等几个方面,介绍了安庆市广播电视台全媒体互动平台的建设方案,为其他广播电视媒体建设全媒体平台、开展全媒体业务提供参考。     

三相多脉波自耦变压整流器和Udc-PWM控制（上）

介绍了三相大功率多脉波自耦变压整流器的基本工作原理和Udc-PWM控制方法。     

Robust Audio Fingerprinting Method Using Prominent Peak Pair Based on Modulated Complex Lapped Transform

The robustness of an audio fingerprinting system in an actual noisy environment is a major challenge for audio‐based content identification. This paper proposes a high‐performance audio fingerprint extraction method for use in portable consumer devices. In the proposed method, a salient audio peak‐pair fingerprint, based on a modulated complex lapped transform, improves the accuracy of the audio fingerprinting system in actual noisy environments with low computational complexity. Experimental results confirm that the proposed method is quite robust in different noise conditions and achieves promising preliminary accuracy results.     

基于UGC大数据挖掘的大群体两阶段风险性应急决策方法

针对在重大突发事件应急决策大数据环境下决策者偏好的不确定性及偏离群体一致性导致的风险,提出一种基于UGC大数据挖掘的大群体两阶段风险性应急决策方法。首先,通过数据挖掘和自然语言处理方法从UGC中获取公众对事件的偏好信息并构建应急决策属性体系,利用TF-IDF方法结合专家评估信息确定属性权重;其次,建立一个意见开放式的两阶段决策流程,提出依据决策者意见的可靠度和准确度量化决策风险,利用聚类方法得到相应的成员权重,并使用TOPSIS法对决策方案进行排序。最后通过天津港“8·12”重大爆炸事故的案例分析和对比验证了所提出方法的可行性和有效性。