反应-膜分离耦合过程的传质特性

在中空纤维膜系统中用纯水及不同浓度的氢氧化钠溶液和二氧化碳混合气进行反应分离,研究了膜分离与化学反应耦合过程的特性。在低二氧化碳进口摩尔分率、低气速及较高氢氧化钠浓度时,化学反应对分离的增强因子非常大．在反应－膜分离耦合体系中,过程阻力与中空纤维膜自身的阻力及溶液中的反应速率有很大关系．由于增加了中空纤维膜阻力,使得二氧化碳的吸收率比较小,但是增加中空纤维数目可以使膜分离器具有巨大的传质表面积,从而有效地弥补了传质速率的不足．因此,适当地选择吸收剂浓度和混合气体流量,可以使反应一膜分离耦合过程达到较高的分离效果,与传统的填料吸收过程相比,在结构、操作和性能上都显示出优越性。     

Surfactant effects on gas absorption in a coke-oven gas treatment process

The effect of organic impurities in industrial stripped coal water (SCW) on the absorption of CO₂ was measured experimentally. Removal of these impurities via activated carbon showed a marked improvement in interphase mass transfer of a vertical wetted-wall column absorber. However, this benefit was not found in a stirred-cell absorber, in which a different flow pattern from that in wetted-wall column absorber is expected. An ad hoc systematic study on the effects of three deliberately added surfactants on gas absorption by pure water in three different absorbers with different flow patterns was thereafter conducted. The experimental results reveal that absorption deterioration also prevails only in a vertical, wetted-wall column absorber and the reduction in liquid phase mass transfer by the addition of surfactant can be satisfactorily correlated with surface pressure of solutions. This indicates that the effect of the industrial impurities in SCW on gas absorption may successfully be simulated under the same flow pattern by a surfactant solution with the same surface pressure. A possible modification of the existing coke-oven gas (COG) treatment process for the benefit of absorption enhancement was finally proposed.     

SAR of a birdcage coil with variable number of rungs at 300 MHz

The specific absorption rate produced in a rat’s brain phantom inside of quadrature birdcage coil as a function of the rung number was studied at 300 MHz. Electromagnetic field simulations and specific absorption rate and loss return responses were performed using a rat’s brain phantom weighing 100 mg. To assure optimal simulations and to evaluate coil performance, S-parameters were simulated and compared with experimentally data. Simulations showed that magnetic field uniformity improves and that electric field is increased with the number of rungs. Specific absorption rate and temperature values obtained from axial bi-dimensional maps increase as the number of rungs grows. These results corroborated very well with published data. A quadrature 16-rung birdcage coil was developed for comparison and phantom images were acquired to show its feasibility. The presented approach yields information on specific absorption rate allowing to previously develop RF coils and their possible effects on the biological sample.     

利用修改的比尔-郎伯定律计算组织吸收对光子平均路径长度的影响

在使用修改的比尔-郎伯定律计算组织的吸收系数以及血氧含量时,平均路径长度(MPL)是一个重要的参数,由此参数可得到微分路径因子(DPF),而DPF通常假定为在一定组织吸收范围内是一个常数.通过腿部的光子蒙特卡罗仿真,本论文使用四种方法来估计MPL,并与MPL的原始定义进行对比.仿真结果表明,DPF显著受到组织吸收的影响,表现为10％的数值变化.因此,使用线性模型将比使用修改的比尔-郎伯定律能更好地计算组织的吸收系数以及血氧含量.     

小型吸收式制冷热虹吸泵的正交试验设计

热虹吸泵是小型无泵溴化锂吸收式制冷机的核心部件,对制冷机的运行及工作性能起关键影响。本文根据溴化锂吸收式制冷循环的设计要求,以热虹吸泵理论模型和性能模拟结果为指导,进行了热虹吸泵沿程加热可视化试验装置的方案设计和部件设计,搭建并调试成功试验装置。采用正交试验法研究加热量、系统压力和沉浸比等因素对热虹吸泵提升性能的影响,分析得知,对于热虹吸泵提升性能影响最大的因素是加热量,次要影响因素是系统压力,沉浸比对其影响最小。     

硫酸干吸工序串酸自控方案的可行性分析与优化

介绍了硫酸干吸工序的串酸机理和自动控制流程,理论分析结果表明,四套可行方案均能利用酸浓和液位参数对干吸系统的串酸量和产酸量实施自动控制,依据实际情况进一步比较优劣,阐述了最为简单直接且易于操作的控制方案.     

Tm~(3+)掺杂KYb(WO_4)_2自激活激光晶体生长与光谱特性分析

以K2W2O7为助熔剂,Tm3+掺杂摩尔分数为8%,采用顶部籽晶提拉法生长出了单斜晶系的铥掺杂钨酸镱钾[Tm3+:KYb(WO4)2,Tm:KYbW]晶体.测试了晶体的红外光谱和Raman光谱,并对出现的峰值进行了振动归属.测量了晶体的吸收光谱和荧光光谱,计算了相应的光谱参数.吸收光谱显示:Yb3+在945,958nm处吸收峰最强,半峰宽为91 nm.荧光光谱表明:Tm:KYbW晶体在1 735nnl和1 759nm附近有较强的发射峰,主峰1 759nm处的发射线宽达146nm,因此,Tm:KYbW晶体可作为可调谐激光增益介质.晶体的上转换荧光谱表明:在481 nm和646nm处分别得到了上转换蓝光和红光,并分析了相应的上转换机制.     

Ag-Cu双金属纳米颗粒在硅酸盐玻璃中的形成过程

利用两步离子交换结合H2气氛热处理的方法,制备出Ag-Cu双金属纳米颗粒/硅酸盐玻璃复合材料.结合吸收光谱和X射线光电子能谱研究了不同工艺条件下Ag、Cu在玻璃中的深度分布、价态变化及其玻璃网络结构的变化.结果表明:掺杂后的玻璃中银和铜的含量随深度不同有所不同.Ag+-Na+离子交换过程中,Ag+与非桥氧结合形成Si-O-Ag键,样品中的银主要以离子状态存在.H2气氛中热处理后,大部分与非桥氧相连的Ag+被还原,H+随即取代Ag+位置,与非桥氧形成-OH结构,还原出来的Ag0经成核和生长形成银纳米颗粒.第二次Cu+-Na+离子交换后,Cu+被引入硅酸盐玻璃,并有二价铜离子存在,再经过H2热处理后,铜离子被还原,在表层聚集生成铜纳米颗粒.     

化妆品中铅含量的测定方法比较

目前,化妆品卫生化学标准检验方法中规定Pb的检验方法有3种,分别为火焰原子吸收分光光度法、双硫腙萃取分光光度法、石墨炉原子吸收光谱法。本文分别采用了火焰原子吸收分光光度法和湿法消解一原子荧光光谱法测定化妆品中痕量Pb,比较得出原子荧光光谱法的分析过程及操作方面比火焰原子吸收分光光度法简单,分析结果的准确度和精密度高。     

填料对吸声涂层材料性能的影响

用自制改性的硅橡胶材料作吸声涂料基料,研究了不同填料对硅橡胶材料吸声性能的影响。结果表明：石墨、空心微粉能够改善硅橡胶吸声性能;其中。石墨能明显提高硅橡胶材料平均吸声系数,且平均吸声系数随石墨用量的增大而增大;石墨用量以20份为宜。