High‐intensity sweeteners in espresso coffee: ideal and equivalent sweetness and time–intensity analysis

The efficient substitution of sucrose by a sweetener in beverages requires the application of some sensory techniques. First, one must determine the concentrations of the sweeteners under study, equivalent in sweetness to the ideal sucrose concentration. In addition, it is fundamental to determine which is most similar to sucrose. The objectives of this study were to determine the ideal sweetness for espresso coffee and the equivalent concentrations in sweetness of different sweeteners, as well as characterise the time–intensity profile of each sweetener in relation to sweetness. The sweeteners evaluated were sucralose, aspartame, neotame, a cyclamate/saccharin mixture (2:1) and stevia. The sucrose concentration considered ideal by consumers was 12.5% (w/v), and the equivalent concentrations of the sweeteners were 0.0159% for sucralose, 0.0549% for aspartame, 0.0016% for neotame, 0.0359% for the cyclamate/saccharin mixture and 0.0998% for stevia. The time–intensity analysis indicated that possibly the sweeteners neotame, aspartame and sucralose would be the best substitutes for sucrose.     

Electrospun melamine-blended activated carbon nanofibers for enhanced control of indoor CO2

Electrospun carbon nanofibers were activated with melamine–polyacrylonitrile [melamine-blended carbon nanofibers (MACNFs)] for use as a fibrous adsorbent for indoor CO₂ removal. Although, melamine doping was intended solely to incorporate basic nitrogen functionalities on the nanofibers, it also shortened fabrication time, conserving time, and energy cost. The specific surface area and microporosity of the fibers were enhanced from 412 m² g⁻¹ and 0.1646 cm³ g⁻¹ to 547 m² g⁻¹ and 0.220 cm³ g⁻¹, respectively, upon final CO₂ activation of the nanofibers. With the chemical properties, we observed significant tethering of pyridine functionality. The sample, MACNF-7 (10 mL of polymer solution doped with 0.7 g of melamine), provided the optimum melamine doping condition to achieve the highest CO₂ adsorption capacity of 3.15 mmol g⁻¹. The adsorption performance was based on simultaneous improvement in microporosity (physical) and surface basicity (chemical) properties of the adsorbent. However, in a binary mixture with nitrogen, the selective adsorption of CO₂ showed the predominance of the improved surface basicity over microporosity. The highest CO₂ selective capture (1.22 mmol g⁻¹) was occurred for a CO₂:N₂ ratio of 0.15:0.85, with a selectivity of 58.19 at 273 K. In a regeneration test, stable and robust performance was achieved more than five cycles. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47747.     

组合赋权的TOPSIS在冲击地压危险性评价中的应用

为了合理准确地评价煤矿冲击地压危险性,在现有评价冲击地压危险性实例的基础上,从煤矿地质因素和开采因素2个方面,选取10个主要的影响指标,利用熵权法和指标相关性权重法分别计算影响冲击地压危险性的各评价指标权重,再根据组合赋权的方法得出各指标的综合权重,构建基于逼近理想解理论的冲击地压危险性评价模型。以重庆砚石台煤矿为例,选取20组评价冲击地压危险性样本数据进行分析,确定评价冲击地压危险性的最优和最劣状况,然后计算出各个评价方案与最优和最劣状况的距离,最后综合最优与最劣距离,确定评价对象的相对贴近度。应用结果表明:评价结果与实际情况一致,且该模型相较其他模型的评价结果更加科学准确,表明该方法有良好的实用价值。     

青草沙水库水质监测布点的优化

青草沙水库建成后已成为上海市最重要的饮用水水源地,合理的监测垂线设置对准确掌握水库水质状况有着重要作用。运用TOPSIS法和物元分析法两种手段对水库现有的10条监测垂线进行优化论证,两种方法的优化结果相同,均优化成8条监测垂线。并对结果的合理性进行论证,对不同时段的数据进行分析,结果表明优化结果受水质季节性变化影响较小;优化后的8条监测垂线空间分布均匀,相邻垂线之间无明显的水质突变,表明优化后的点位已能较好地反映库区水环境。     

隧道中气囊阻漏的工作机理及模型试验研究

近年来,地下隧道工程发展迅速,在建设和使用过程中的突发事件也层出不穷。地下隧道常经过含水丰富的土层或岩层裂隙发育地带,因此容易发生渗漏或者涌水突泥的问题。为减少工程损失,需尽快将涌水区隔离,为进一步的处置争取时间。采用大尺寸橡胶气囊进行隧道挡水,是通过快充而膨胀的气囊与隧道内壁之间产生的摩擦力抵消水压力,将水阻隔在气囊一端,避免涌水面积扩大。本文假设气囊材料不可拉伸,内部气体满足理想气体状态方程,通过分析气囊的受力情况和边界条件,对气囊在充气过程中和一端有外力时的形状和受力特点试验和理论研究,得到气囊受到外压时整体形状和内部气压的理论公式,以及外压与内压的关系,提出气囊阻水的设计计算方法。通过模型试验对变化规律、公式和气囊失稳方式进行了对比分析,研究结果表明,隧道中气囊正常工作需同时满足3个控制条件:(1)一端的外压必须小于气囊的内压;(2)气囊的张拉力必须小于气囊材料的抗拉强度;(3)外荷载推力必须小于气囊与隧道壁之间的最大摩阻力。通过理论研究所得的气囊失效机理和内压增长规律与模型试验所得结果有较高的一致性,研究成果可作为隧道中大尺寸胶囊设计的依据。     

蒙太奇的回归——泰安市水利与渔业局办公楼及综合服务楼设计

通过分析蒙太奇的艺术模式在建筑创作中的作用,印证了当今信息化社会需要建筑师拥有蒙太奇式的审视角度和解决方法。结合泰安市水利与渔业局办公楼及综合服务楼的设计实践,探讨了如何以建筑师和电影人的双重视角来从事建筑创作,用电影思维启发灵感,用电影语言表达构思,以实现对创造未来理想空间的追求。     

黄土地下隧道开挖对周围土体变形的影响分析

以西安地铁一线工程为背景,基于黄土力学参数,运用岩土工程数值分析软件FLAC3D,进行了黄土地层地下隧道开挖对周围土体变形影响的计算机模拟分析。根据黄土场地的实际条件,建立了隧道的计算模型,利用FLAC3D程序,模拟了黄土隧道开挖过程中前期支护条件、后期加固措施等因素对隧道内部地表、拱顶、侧墙以及地上建筑物沉降的影响程度和塑性区、位移的分布规律。可为黄土地区的地下工程建设提供一定的参考。     

新世纪的山水城市

论述了山水城市的概念形成及其产生背景,阐述了建设山水城市的内涵和意义,指出山水城市是21世纪中国城市发展的理想模式,从而达到改善人类生活环境,提高人类生活质量的目的。     

金玉兰广场酒店结构设计

金玉兰广场酒店是一幢52层超高层酒店建筑。层48以下结构采用钢筋混凝土框架-核心筒体系,以上采用钢框架-钢筋混凝土筒体,建筑高度226m。由于建设单位原因,在施工到层34时,业主建议再加建3层,共14.4m高,办公用途;顶部钢架40m。针对工程特点和过程中发生的重大设计变更情况,重点介绍了塔楼的结构方案、线性与非线性分析、顶部巨型钢架的设计;过渡层、型钢混凝土和钢结构两种结构形式的梁柱节点、万向铰接柱脚等设计中需要解决的相关问题。