便携式标准湿度发生器干气装置的研制

介绍了一种为混合法标准湿度发生器提供干燥气源的可再生重复使用的干气装置。混合法湿度发生器在湿度发生原理上需要一股干气源,本装置克服了以往大多干燥装置体积大、质量大、输出气体霜点温度值偏高等缺点,采用分级干燥和变色指示的方法,体积小、质量小、可重复使用、便于携带,其输出干燥气霜点温度可达-70℃以下。     

Improving iris recognition performance via multi-instance fusion at the score level

Fusion of multiple instances within a modality for biometric verification performance improvement has received considerable attention. In this letter, we present an iris recognition method based on multiinstance fusion, which combines the left and right irises of an individual at the matching score level. When fusing, a novel fusion strategy using minimax probability machine （MPM） is applied to generate a fused score for the final decision. The experimental results on CASIA and UBIRIS databases show that the proposed method can bring obvious performance improvement compared with the single-instance method. The comparison among different fusion strategies demonstrates the superiority of the fusion strategy based on MPM.     

Numerical simulation for separation of multi-phase immiscible fluids in porous media

Based on a lattice Boltzmann method and general principles of porous flow, a numerical technique is presented for analysing the separation of multi-phase immiscible fluids in porous media. The total body force acting on fluid particles is modified by axiding relative permeability in Nithiarasu＇s expression with an axiditional surface tension term. As a test of this model, we simulate the phase separation for the case of two immiscible fluids. The numerical results show that the two coupling relative permeability coefficients K12 and K21 have the same magnitude, so the linear flux-forcing relationships satisfy Onsager reciprocity. Phase separation phenomenon is shown with the time evolution of density distribution and bears a strong similarity to the results obtained from other numerical models and the flows in sands. At the same time, the dynamical rules in this model are local, therefore it can be run on massively parallel computers with well computational efficiency.     

温度敏感聚(N-异丙基丙烯酰胺)/聚(乙烯醇)水凝胶的制备及性能研究

聚 (N -异丙基丙烯酰胺 ) (PNIPA)水凝胶具有温度敏感性 ,其在 33℃左右有一个相转变温度或较低临界溶解温度 (L CST) [1,2 ] .当外界温度低于 LCST时 ,PNIPA水凝胶吸水溶胀 ;而当外界温度高于L CST时 ,PNIPA水凝胶剧烈收缩失水 ,发生相分离 .这种相分离特性应用于药物的控制释放 [3] .固定化酶[4 ] 和循环吸收剂 [5] 等领域 .然而 ,通常的 PNIPA水凝胶是通过化学键交联而成的三维网络聚合物 ,很难发生解体或进行生物降解 ,其在某些特定场合 (如药物的体内释放等 )受到一定限制 .聚乙烯醇 (PVA)的亲水性和生物相容性较好 ,是…     

低温冷库热气融霜冷凝热的季节匹配度分析

在对低温冷库冷负荷构成进行分析的基础上,分析了制冷系统冷凝热随季节(即环境温度)变化的特点,定义了"季节系数",即冬季与夏季能用于热气融霜的冷凝热量之比,其意义是季节对制冷系统冷凝热量的影响程度,季节系数小说明影响程度大,即冷凝热量与季节的匹配度差,反之说明影响程度小、匹配度好。讨论了制冷剂为R22和R404A的制冷系统在不同名义冷凝温度下的季节系数的特点。结果表明:季节系数随制冷剂和名义冷凝温度的不同而不同,在名义冷凝温度一定时,R22的季节系数比R404A的小;而对同一种制冷剂,名义冷凝温度越低,季节系数越小;且R404A的季节系数受名义冷凝温度的影响更为明显。本研究为热气融霜技术的工程设计与推广提供了参考。     

低温泵用吸附材料的研究概述

低温泵广泛应用于真空电子、半导体领域。低温泵的吸附材料对低温泵的工作性能有着重要的影响。综述了低温泵的吸附材料性能与研究现状。首先总结了吸附材料的表征方法及研究内容。然后分别叙述了分子筛、低温霜和活性炭三种低温泵主要用的吸附材料的工作性能,指出其优势和不足。最后以ITER用的低温泵为例说明低温吸附材料的应用。     

防晒BB霜的配方研究

介绍了BB霜的现状和不足,讨论了防晒BB霜配方的设计原理、配方和生产工艺。配方设计原理中重点介绍UVA和UVB如何搭配使用,丁基甲氧基二苯甲酰基甲烷、水杨酸乙基己酯、甲氧基肉桂酸乙基己酯、纳米级钛白粉(二氧化钛)是常用的化学防晒剂和物理防晒剂。     

AN ITERATIVE HYBRIDIZED MIXED FINITE ELEMENT METHOD FOR ELLIPTIC INTERFACE PROBLEMS WITH STRONGLY DISCONTINUOUS COEFFICIENTS

An iterative algorithm is proposed and analyzed based on a hybridized mized finite element method for numerically solving two-phase generalized Stefan interface problems with strongly discontinuous solutions,conormal derivatives,and coefficients.This algorithm iteratively solves small problems for each single phase with good accuracy and exchange information at the interface to advance the iteration until convergence ,following the idea of Schwarz Alternating Methods,Error estimates are derived to show that this algorithm always converges provided that relaxation parameters are suitably chosen,Numeric exper-iments with matching and non-matching grids at the interface from different phases are performed to show the accuracy of the method for capturing discontinuities in the solutions and coefficients.In contrast to standard numerical methods,the accuracy of our method does not seem to deteriorate as the coefficient discontinuity increases.     

低霜点校准系统

介绍了一种能产生低于—100C霜点的校准系统。该系统将一股干气与一股湿气进行混流,干气用一个液氮冷槽产生。同时还介绍了几个有用的设计特点,如:在气流通路中不含一头封闭的支路,取消了干气通路上的阀门和流量计。通过在—99～—58C霜点范围内校准氧化铝湿度计探头,对该系统进行了验证。