膜态沸腾球体水下运动减阻特性

为揭示膜态沸腾球体水下运动减阻机理,基于计算流体力学方法,采用Mixture多相流模型,耦合蒸发-冷凝相变模型,对亚临界雷诺数范围内的膜态沸腾球体绕流减阻特性进行数值仿真,得到的阻力系数与文献[11]实验结果具有较好的一致性。对比分析了普通球体与膜态沸腾球体的绕流特性,研究了雷诺数对膜态沸腾球体绕流特性的影响,分析了膜态沸腾球体绕流运动减阻机理。仿真结果表明:膜态沸腾球体蒸汽膜的存在使球体壁面的无滑移边界条件转化为蒸汽膜的滑移边界条件,减小了壁面对流体的粘滞作用,使流动分离点向尾部移动,减小了球体绕流阻力;蒸汽会在球体尾部发生堆积,随着雷诺数的增大,堆积位置向后移动,阻力系数变小,尾部流动更趋于流线型。     

纳米Mn-Zn铁氧体制备过程中的元素补偿研究

采用回流制备方法,通过对比实验和化学定量分析,研究了Fe2+的催化作用以及对Mn、Zn元素实施补偿的可行性,得出试样中金属元素的摩尔比。实验发现:pH≤9.6时,Fe2+对合成反应具有明显的催化作用。初始pH>7时,Zn元素能进行补偿;初始pH>8.5时,Mn元素才能进行补偿。XRD和TEM研究表明,Mn-Zn铁氧体纳米粒子为球形,平均粒径约为4.35nm。     

PROTEIN PRECIPITATION DURING WORT BOILING: QUALITY ASPECTS OF DIMINISHED WORT BOILING TIMES OF BREWS PREPARED FROM PROANTHOCYANIDIN-FREE OR REGULAR RAW MATERIALS

When using proanthocyanidin-free materials for the production of beer, a reduction of the wort boiling time can be considered. In worts prepared with regular malt and tannin-free hop extract there is a continuous precipitation of the malt flavanoids while in brews prepared from proanthocyanidin-free malt and regular hops there is a simultaneous extraction and removal of the hop flavanoids leading to constant levels of these hop flavanoids. The results also show that the level of Kjeldahl nitrogen in worts boiled with hops will be the same as that in worts boiled with n-hexane tannin-free hop extracts. These results and the fact that more protein precipitates in brews containing no malt or hop proanthocyanidins suggest that, unlike what is the case during the development of beer haze, polyphenols are not necessary for an effective protein precipitation during wort boiling.     

亲水易染型聚酯纤维及其织物性能

 对亲水易染型逸绵纤维及其织物性能进行了介绍,重点介绍了易染型逸绵纤维及其纱线产品的基本物理指标,易染型逸绵纤维织物的染整加工特性和织物性能。易染型逸绵纤维可以使用分散染料常压沸染,其和棉混纺织物可以一浴一步染色,有较好的节能效果,其强度适中,手感柔软,亲水性好,有很好的仿棉特性。易染型逸绵织物吸湿速干性大大优于常规聚酯纤维织物和纯棉织物,适合开发各种休闲面料和运动面料,应用前景非常广阔。     

Fracture Resistance of Cashew Nuts as Influenced by Pre-Shelling Treatment

The fracture resistance of raw and pre-treated cashew nuts during uni-axial compressive loading was investigated. Cashew nut samples were subjected to two pre-shelling treatments, namely: steam boiling and roasting in hot cashew nut shell liquid. Two loading rates of 2.5 and 50 mm/min and two loading orientations (longitudinal and transverse) were considered for fracture resistance of pre-treated cashew nuts using a 50 kN capacity Instron testing machine. The data obtained were subjected to analysis of variance. The average values at 2.5 mm/min were 342 and 318 N for raw nuts, 321 and 242 N for roasted nuts, and 341 and 309 N for steam boiled nuts during longitudinal and transverse loading, respectively; whereas corresponding values at 50 mm/min were 784 and 763 N for raw nuts, 517 and 464 N for roasted nuts, and 436 and 398 N for steam boiled nuts, respectively. In each of the pre-treatment methods and loading rates, more force was required to crack cashew nuts during longitudinal loading than transverse loading; and for each loading rate, pre-treated nuts generally required less force than raw nuts.     

基于高效液相色谱法的麻辣火锅底料辣度分级模型建立及其在熬煮过程中的变化

基于高效液相色谱法结合感官评价结果,采用SPSS中的Fisher判别分析方式,对火锅底料进行辣度分级,得到麻辣火锅底料的辣度分级模型;研究熬煮过程中辣椒素类物质（capsaicinoids,Cap-S）的含量变化,得到其影响辣度分级的规律。结果表明,仅用感官评价对火锅底料进行辣度分级受感官评价人员的影响较大,结论准确度不高;若以火锅底料中Cap-S含量为分级标准,其正判率界值为24%＞20%,可以很好地将辣度分为5 个等级,分级模型较为合理。火锅底料熬煮过程会影响Cap-S的迁移,Cap-S在油相和水相中处于动态平衡状态,同时调味料中的Cap-S逐渐迁移到汤底中,使得熬煮过程中辣度总是不断发生变化。高效液相色谱法结合感官评价结果对火锅底料进行辣度分级,可以很好地区分火锅底料的辣度,指导消费者购买合适的食品。     

不同蒸煮方式青蟹肌肉感官品质分析和比较研究

为研究热水上锅蒸(热蒸)、热水下锅煮(热煮)、冷水上锅蒸(冷蒸)和冷水下锅煮(冷煮)青蟹肌肉感官品质差异,对4种烹制方式下青蟹肌肉感官品质进行分析与比较.结果表明:冷蒸雄蟹和热蒸雌蟹肌肉的感官评价较好;利用游离氨基酸的味觉活度值进行滋味分析,发现肌肉整体滋味偏甜,甜味的主要来源为甘氨酸、丙氨酸和精氨酸,且冷蒸雄蟹肌肉和...     

双头纺33dtex/12f涤纶高收缩FDY的生产及探讨

介绍了运用双头纺技术,在嫁接PET纺丝生产线上生产33dtex/12 f涤纶高收缩丝的工艺技术特点,着重讨论了预结晶温度、时间、纺丝温度、拉伸定型等因素对高收缩丝生产及收缩性能的影响。     

麦汁煮沸中相关问题的探讨

麦汁煮沸是啤酒酿造中糖化工段的一项重要的操作过程。该文通过对煮沸热传导原理及几种不同麦汁煮沸设备的介绍,提出了麦汁煮沸控制措施和结垢处理方法,以及使用麦汁煮沸装置时的注意事项。