The experimental measurement and theoretical analysis of flow-system tracer curves by a line-sampling method

An electrical conductivity sampling probe for the accurate measurement of the dispersive effect of velocity gradient on concentration profile has been designed. The probe averages tracer concentration along a single diameter of the tube. The impulse response of this probe system in steady laminar flow in a tube has been derived theoretically and confirmed experimentally. Examples of the determination of unknown velocity profiles by tracer techniques utilizing the probe are presented.     

制造企业生产模式的变迁引发的哲学思考

分析了制造企业生产模式的发展历程，研究了人在不同的生产模式中的地位和作用。传统制造企业生产模式常常对人的情感产生冲击，文中对其产生的原因进行了分析，并提出了解决办法。     

Chemistry and nanoparticulate compositions of a 10,000 year-old ice core melt water

Particulates extracted from a single section of a 10,000 year-old ice core melt sample exhibited characteristics of contemporary, airborne fine particulates: a majority were microcrystalline particulates and aggregated microcrystals, including some mixtures of microcrystals and carbonaceous matter. Particularly significant were the presence of carbon nanotubes and fullerene nanocrystals composing aggregated particulates reflecting global combustion products similar to contemporary, airborne carbon nanocrystal aggregates. ICP elemental analysis of the melt water showed significant concentrations of Ca, K and especially Na (corresponding to K, NaCl), S, Si, Se, and Zn. Overall, the elemental analysis of the melt water is similar to local tap water. However, lead was absent in the local tap water and only half the concentration of selenium was present in the tap water in contrast to the ice core water. While these observations cannot be generalized, the methodology illustrates the potential to characterize and compare airborne particulate regimes and water chemistries in antiquity.     

Carbon nanotubes and other fullerene nanocrystals in domestic propane and natural gas combustion streams

Carbon nanotubes and other aggregated fullerene-related multi-layer shell structures have been collected in propane and natural gas flame emissions from domestic cooking stoves and observed by transmission electron microscopy. Some aggregated nanoparticles collected on 3 mm electron microscope grids by thermal precipitation were mostly multi-walled nanotubes; many tangled and distorted, and aggregated with other closed-concentric, multi-shell forms. Such clean-burning regimes may be major contributors to complex particulate matter in indoor and outdoor air.     

Syntheses of amine-type adsorbents with emulsion graft polymerization of glycidyl methacrylate

Glycidyl methacrylate (GMA) which was precursor monomer for the synthesis of metal ion adsorbent was emulsified by surfactant of Tween 20 (Tw-20). The emulsion of 5% GMA in the water was stable for 48 h at Tw-20 concentration of 0.5%. Graft polymerization of GMA on polyethylene fiber was carried out in the emulsion state at various pre-irradiation doses. Degree of grafting (Dg) reached 103%, 301% and 348% for 1 h grafting at 40 °C with pre-irradiation of 10, 30 and 40 kGy, respectively. But the Dg was depressed when the pre-irradiation dose was over 50 kGy since cross-linking occurred simultaneously in the trunk polymer. Dg decreased with increment of Tw-20 concentration in emulsion of 5% GMA at pre-irradiation of 40 kGy. The three kinds of amine-type adsorbents were synthesized by reacting diethylenetriamine (DETA), triethylenetetramine (TETA) and ethylenediamine (EDA) with GMA-grafted polyethylene fiber. The synthesized EDA-type adsorbent had the highest selectivity against U ion and the distribution coefficient was 2.0 × 10⁶.     

Multiple block coded modulations and applications to unequal error protection

Multiple block coded modulations (MBCM) are studied. One characteristic of the studied MBCM schemes is that they have both a block and a trellis structure. A general rule for deriving branch variables so as to establish a decoding trellis is presented. Examples of MBCM schemes employing 8‐PSK and 16‐PSK constellations are given. Two different methods using these schemes are proposed for producing unequal error protection. Computer simulations are done to show the UEP ability. This revised version was published online in August 2006 with corrections to the Cover Date.     

Preparation and Characterization of 4,4′‐Bis(4‐aminophenoxy)diphenyl Sulfone Based Fluoropoly(ether‐imide)/Organo‐Modified Clay Nanocomposites

A series of fluoropoly(ether‐imide) (6F‐PEI), and [6F‐PEI/montmorillonite (MMT) clay) nanocomposites films were made by thermal curing of respective formulations containing fluoropoly(ether‐amic acid) (6F‐PEAA), synthesized from 2,2′‐bis(3,4‐dicarboxyphenyl)hexafluoropropane dianhydride (6FDA) and 4,4′‐bis(4‐aminophenoxy)diphenyl sulfone (p‐SED), and increasing concentration of p‐SED treated montmorillonite clay (modified MMT clay) at temperature from RT to 350 °C. These films showed excellent solvent resistance as well as very good thermal stability, and increased glass transition (T_g) values with increasing % clay. In addition, these trifluoromethyl groups‐containing nanocomposites films showed sharp lowering of coefficient of thermal expansion (CTE) by 22%. Furthermore, they exhibited increased long‐term thermo‐oxidative stability (TOS), with % weight retention in the range of 86 to 92% in isothermal heating at 300 °C for 300 h in air, reduced water absorption at 100 RH at 50 °C in the range of 0.5 to 1.15%. These data are still much lower than those of neat ULTEM® 1000 and Kapton® H film. The modulus of elasticity is on an average 38% higher for the nanocomposite films relative to neat fluoropoly(ether‐imide) (6FDA + p‐SED), and above non‐fluorinated polyimide films. The surface energy measurement by One‐Liquid and Two‐Liquid method showed a comparable trend of decreasing contact angle. For the nanocomposite films having 15% hydrophobic clay, the contact angle decreased by 21 and 20% for DI‐water and formamide, respectively. The surface energy increase was in the range of 8.21–8.54 mJ/m².

     

基于改进区域化流量历时曲线的无资料 地区径流模拟

台湾成功大学游保杉教授等人创造性地采用区域化流量历时曲线率定法,利用所推求的区域化流量历时曲线作为水文模型的拟合目标,率定无资料地区的参数,实现了无资料地区径流模拟。作为该法应用的关键,区域化流量历时曲线精度直接关系到模型率定的精度。研究通过趋势拟合对推求的流量历时曲线在形态上进行校正且利用量级调整对曲线的量级大小进一步进行调整,逐步改进区域化流量历时曲线。以此,提高了区域化流量历时曲线率定法的精度,较好地实现了无资料地区日径流过程模拟。