基于主分量方法对宁德水环境现状评价

在分析宁德市区地表水状况的基础上,对地表水进行了评价.评价结果表明:宁德市地表水以工业和城市生活污染为主,以城市内河污染较严重.按照生态可持续发展的要求,从加强城市污水处理建设、实行科学决策和发展生态农业等方面,提出了宁德市地表水环境保护对策.     

基于响应面法的钢拱桥可靠度分析

大型复杂桥梁结构的极限状态函数都是隐式的非线性函数,采用传统的可靠性分析方法可能无法实现,但利用响应面有限元法可以很好地解决这类问题。利用响应面法对一下承式钢拱桥拱肋、主梁在正常使用极限状态下的轴向应力、竖向位移的可靠度进行了分析,并根据拟合出的各极限状态函数显式表达式得出了相应的可靠度指标,说明响应面有限元法是计算下承式钢拱桥构件可靠度的有效方法。     

推导球形液面产生的附加压强的一种方法

运用功能原理,借助表面能概念推导球形液面产生的附加压强。     

Technological parameters for preparation and granulation of ammonium ion-exchange material

As a raw material,kaolin was modified to prepare a high-performance ammonium ion-exchange material.According to cation-exchange capacity (CEC) measurement,the prepared ammonium ion-exchange material has an ammonium ion-exchange capacity greater than 75mg/g and can be used to remove ammonia nitrogen in water treatment.A pharmaceutical extruder-rounder was used to study the effects of granulation process.Polyethylene glycol6000 (PEG-6000) was used as the pore-forming agent and calcining temperature of 650℃ was used as the optimal condition.NMR data indicate that 27 Al is mainly converted from hexa-coordinated Al to tetra-coordinated Al during the modification.Compared with 29 Si in the original kaolin,29 Si in the modified kaolin does not have an obvious change.A comparison of the data with Langmuir and Freundlich isotherm models shows a good correlation.The Freundlich model describes the process more accurately,and the adsorption process of ammonia nitrogen in water with the ammonium ion-exchange material closely matches the pseudo-second-order reaction.     

聚乙二醇型双联表面活性剂的合成工艺研究

以硬脂酸和聚乙二醇为原料,经酯化后生成聚乙二醇双酯。再经磺化剂氯磺酸的磺化作用下得α-磺基硬脂酸聚乙二醇双酯,加NaOH中和后成盐,形成α-磺基硬脂酸聚乙二醇双酯钠盐。实验结果表明,在催化剂用量为2.0%(基于反应体系的质量分数),酸醇的量比为2.5∶1.0,反应时间为4小时,反应温度140~150℃时,聚乙二醇双酯收率达83%。磺化剂氯磺酸与双酯的量比为2.4∶1.0,反应时间为1小时,反应温度为60~70℃,α-磺基硬脂酸聚乙二醇双酯收率为96%。α-磺基硬脂酸聚乙二醇双酯钠盐的总收率为79.7%。     

The acute effects of bodyweight suspension exercise on muscle activation and muscular fatigue

This investigation examined effects of two exercise modes (barbell, BB; bodyweight suspension, BWS) on muscle activation, resistance load, and fatigue. During session one, nine resistance-trained males completed an elbow flexion one-repetition maximum (1RM). During sessions two and three, subjects completed standing biceps curls to fatigue at 70% 1RM utilizing a randomized exercise mode. Surface electromyography (sEMG) recorded muscle activation of the biceps brachii, triceps brachii, anterior deltoid, posterior deltoid, rectus abdominis, and erector spinae. BWS resistance load was measured using a force transducer. Standing maximal voluntary isometric contractions of the elbow flexors recorded at 90° were used to determine the isometric force decrement and rate of fatigue (ROF) during exercise. sEMG and resistance load data were divided into 25% contraction duration bins throughout the concentric phase. BWS resulted in a 67.7?±?7.4% decline in resistance load throughout the concentric phase (p?≤?0.05). As a result, BB elicited higher mean resistance loads (31.4?±?4.0?kg) and biceps brachii sEMG (84.7?±?27.8% maximal voluntary isometric contractions, MVIC) compared with BWS (20.4?±?3.4?kg, 63.4?±?21.6% MVIC). No difference in rectus abdominis or erector spinae sEMG was detected between exercise modes. Isometric force decrement was greater during BWS (?21.7?±?7.0?kg) compared with BB (?14.9?±?4.7?kg); however, BB (?3.0?±?0.8?kg/set) resulted in a steeper decline in ROF compared with BWS (?1.7?±?0.6?kg/set). The variable resistance loading and greater isometric force decrement observed suggest that select BWS exercises may resemble variable resistance exercise more than previously considered.     

液体表面张力现象错误认识的大气压反推法

从理论、反推和实际计算三方面对一种液体表面张力现象展开推证;最终证实：底面平整物体被缓慢拿离水面时受到的阻力,并非大气压力作用,而是液体表面张力作用的结果．     

全脐点弯曲曲面及其上曲线的若干性质

本文论证了全脐点曲面必为球面或平面 ,并讨论了球面曲线的一系列性质 ,揭示了这类曲线的曲率和挠率之间的特殊关系 ,从而刻画出其几何特征。     

新中国家用电器外功能表面的本土化演变

基于历史文献、实物资料考据,阐述建国后家用电器外功能表面设计本土化的演变过程。通过对家用电器外功能表面材质与装饰的研究,分析建国初期家用电器从无到有、从少到多的演变以及外功能表面设计风格从洋为中用、中西结合,到最终形成独具中国审美、具有时代特色的式样的成因。     

从近年奥运报道看媒体的场域变化

利用布尔迪厄提出的场域理论分析北京奥运和伦敦奥运报道中媒体场域的变化,以思考新媒体对奥运报道场域的影响.认为奥运报道中的游戏规则在近年来变化尤其明显,特别表现在网络社交媒体的加入上,其从侧面改变了主流媒体报道奥运的方式,使得受众的意见越来越重要,奥运报道媒介场中的张力更大,各种力量的博弈变得更均衡.