电阻分联及其应用——电阻串并联的一个逆问题

介绍电路分析的一种新方法,称为电阻分联法.文中附有几个应用实例.这工作可看作是电学中逆问题一例.     

Monitoring of ducting by using a ground-based GPS receiver

In this paper,we describe the estimation of low-altitude refractivity structure from simulation and real ground-based GPS delays.The vertical structure of the refractive environment is modeled using three parameters,i.e.,duct height,duct thickness,and duct slope.The refractivity model is implemented with a priori constraints on the duct height,thickness,and strength,which might be derived from soundings or numerical weather-prediction models.A ray propagation model maps the refractivity structure into a replica field.Replica fields are compared with the simulation observed data using a squarederror objective function.A global search for the three environmental parameters is performed using a genetic algorithm.The inversion is assessed by comparing the refractivity profiles from the radiosondes to those estimated.This technique could provide near-real-time estimation of the ducting effect.The results suggest that ground-based GPS provides significant atmospheric refractivity information,despite certain fundamental limitations of ground-based measurements.Radiosondes are typically launched just a few times daily.Consequently,estimates of temporally and spatially varying refractivity that assimilate GPS delays could substantially improve over-estimates caused by using radiosonde data alone.     

铜(Ⅱ)在双表面活性剂液膜体系中的迁移行为

乳状液膜分离技术具有快速高效、选择性强、富集比大等优点[1-4],但该技术目前大多还处在实验阶段,要实现工业化则必须解决液膜稳定性、有毒试剂的使用及二次污染等问题.表面活性剂对于乳状液膜的形成和稳定至关重要[5-7],而在液膜体系中采用复合表面活性剂,能改善液膜性能,提高膜稳定性及传质效率[8].本文研究了铜(Ⅱ)在span80-SDS-NH3液膜体系中的迁移行为.体系中无流动载体,利用内、外相中被分离物的浓度梯度促进物质迁移.当Cu2+进入内相时,与NH3产生络合反应,使内相中游离的铜离子浓度趋于零而促使其由外相进入内相,实现Cu2+与外相溶液的分离.     

刚果红分光光度法测定血清蛋白质

1　引　　言蛋白质的定量测定在生物化学、药学及食品等学科中有重要意义 ,也是临床诊断疾病及检查治疗效果不可缺少的分析项目。蛋白质含量测定方法很多 ,目前研究最多、应用最广的为染料结合法 ,但未见有刚果红作显色剂测定蛋白质的报道。研究了刚果红与蛋白质反应的基本条件 ,建立了以刚果红测定蛋白质的分光光度分析法 ,用于实际人血清样品中总蛋白质的测定 ,取得了满意的结果。与经典的考马斯亮蓝法比较 ,本法简便灵敏 ,稳定性好 ,线性范围较宽 ,颇有实用意义。2　实验部分2 .1　主要仪器及试剂　Ｌａｍｂｄａ 3 5紫外 可见分光光度计 …     

L波段三维ESR成像系统的研制（Ⅱ）——L波段三维ESR成像系统

叙述了一个L波段（1.05 GHz）用于ESR和ESR成像的装置，用这套自制装置实现了3D ESR成像. 该装置由L波段ESR谱仪、三组梯度场线圈及控制单元和PC机数据采集系统组成. 样品腔是一个3-环2-缝再进入式谐振腔，可放入直径为20 mm、 长30 mm的H₂O样品，空谐振腔的频率是1.05 GHz. 微波振荡频率用自动频率控制（AFC）的方法自动锁在有载腔的频率上. 梯度场线圈沿X-，Y-和Z-轴产生线性梯度场，在中心40 mm球形范围内梯度场强度为2 mT/cm. 依照Lauterbur's方法进行3D ESR 图像重建. 用该系统检测了样品中TEMPO氮氧自由基的3D空间分布. 得到了TEMPO的2D、3D ESR图像、用像素灰度表示的自旋密度分布图及3D ESR-CT图像.     

Geometry of 2×2 hermitian matrices

Let D be a division ring which possesses an involution a→ā. Assume that F = {a∈D|a=ā} is a proper subfield of D and is contained in the center of D. It is pointed out that if D is of characteristic not two, D is either a separable quadratic extension of F or a division ring of generalized quaternions over F and that if D is of characteristic two, D is a separable quadratic extension of F. Thus the trace map Tr: D→F,hermitian matrices over D when n≥3 and now can be deleted. When D is a field, the fundamental theorem of 2×2 hermitian matrices over D has already been proved. This paper proves the fundamental theorem of 2×2 hermitian matrices over any division ring of generalized quaternions of characteristic not two.     

电感耦合等离子体原子发射光谱法测定紫砂壶中12种重金属元素

采用电感耦合等离子体原子发射光谱法测定真假紫砂壶中砷、钡、铋、镉、铬、铁、汞、锰、镍、铅、锑和锡等12种重金属元素。紫砂壶样品用盐酸(10+90)溶液浸泡4h,仪器高频功率为1 150 W,辅助气流量0.5L·min-1,载气流量0.5~0.6L·min-1,观察高度9mm。12个元素的质量浓度均在5.00 mg·L-1以内与其发射强度呈线性关系,方法的检出限(3s/k)在0.002~0.010mg·L-1之间。加标回收率在93.0%~105%之间,测定值的相对标准偏差(n=21)在0.24%~0.83%之间。     

一种黄土高边坡设计的新方法

根据黄土高边坡破坏面的实际特征,假定最危险滑动面为抛物线型,对高边坡进行可靠度分析,应用数学原理,建立了黄土高边坡的设计模型,并对铜黄一级公路黄土高边坡进行分析验证,结果表明,该方法计算的结果与实际较接近。该方法物理意义明确,易操作,可供设计人员参考。     

ON THE SENSITIVE DYNAMICAL SYSTEM AND THE TRANSITION FROM THE APPARENTLY DETERMINISTIC PROCESS TO THE COMPLETELY RANDOM PROCESS

The detailed analysis of the dynamical process of coin tossing is made.Throughcalculations,it is illustrated how and why the result is extremely sensitive to the initialconditions.It is also shown that,as the initial height of the mass center of the coin increase,the final configuration,i.e."head" or "tail",becomes more and more sensitive to the initialparameters(the initial velocity angular velocity,and the initial orientation),the coefficientof the air drag,and the energy absorption factor of the surface on which the coin bounces.Ifwe keep the"head" upward initially but allow a small range for the change of some otherinitial parameters,the frequency that the final configuration is"head",would be I if theinitial height h of the mass center is sufficiently small,and would be close to 1/2 if h issufficiently large.An interesting question is how this frequency changes continuously fromI to 1/2 as h increases.Detailed calculations show that such a"transition"is very similarto the transition from laminar to     

具非凸流函数守恒律周期解渐近性质

讨论具非凸流函数双曲守恒律周期解的渐近性质，得到较以往更为一般的结果。