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排序方式: 共有312条查询结果,搜索用时 750 毫秒
61.
介绍射频辉光放电等离子体改善苎麻织物毛细效应的时效性的实验。分别在充入氩气、氮气、氧气的真空室中对苎麻织物进行射频辉光放电等离子体处理,在每一种处理过程中分别改变其处理时间、放电功率和真空室压强。测试了放置不同时间的经不同等离子体参数处理后的苎麻织物的毛细效应,得出各种参数的等离子体处理对苎麻织物毛细效应时效性的影响。实验结果表明,苎麻织物被等离子体离子体处理后毛细效应得到明显改善,其毛细效应随放置时间的变化为先快速下降,然后变缓,逐渐趋于稳定,这种毛细效应的改善具有良好的时效性,其中100W、40Pa的氧等离子体处理20分钟后的苎麻织物的毛细效应时效性最好。 相似文献
62.
It was investigated how risk estimates derived from the RERF life span study data sets for cancer incidence and mortality, respectively, differ between the two cities Hiroshima and Nagasaki, and the two sexes. This was done by estimating the excess risk for various age-at-exposure and time-since-exposure groups. The epidemiologically most reliable age group are those aged 20–39 years at the time of exposure. As expected, in this group, the relative risk for females in Hiroshima is higher than that for males; however, in Nagasaki, the relative risk for females is lower than that for males. When comparing the risks in the two cities for the same sex, the risks of cancer incidence and mortality of females exposed in Hiroshima are higher than those in Nagasaki. However, for the males, the risks of cancer incidence in Hiroshima are lower than in Nagasaki, and the risks of cancer mortality of males are very similar between both cities. All differences depend on age-at-exposure and time-since-exposure, and are at the borderline of being statistically significant. The absorbed dose of neutrons, for the same γ-dose, is about three times as high in Hiroshima than in Nagasaki for both sexes. Because of these observed risk differences between both cities, it does not appear to be possible to reliably estimate the relative biological effectiveness of neutrons as compared to that of γ-rays from these epidemiological data sets. No evidence was found in this analysis that the radiation weighting factors wR presently used for neutrons in radiation protection could severely underestimate the risks for somatic late effects induced by neutrons. 相似文献
63.
基于预测有效度的非负变权组合预测模型研究 总被引:4,自引:0,他引:4
本以预测方法有效度为准则,分别在样本区间、预测区间及总区间上建立了非负变权的组合预测模型,并给出其线性规划的解法,该模型具有较二次规划计算简便的特点,而且目标函数具有可比性,能反映不同指标序列预测方法有效性,同时变权能适应外界环境的变化。 相似文献
64.
Mixed micelle formation and surface tension reduction effectiveness (γcmc) were investigated for the following systems: triethanolammonium dodecylpoly(oxyethylene)sulfate (TADPS, containing about
two ethylene oxide units)/dodecyltrimethylammonium bromide, TADPS/hexadecyltrimethylammonium bromide and TADPS/hexadecylpyridinium
chloride. For all these anionic/cationic systems, the mixed critical micelle concentration (cmc) values reflect a strong synergism
in mixed micelle formation, with βM values ranging from −13.8 to −18.3. The mixed micelle composition is mixing-ratio dependent and, for equimolar mixtures,
the mixed micelle is richer in the surfactant with the lower cmc. Precipitation is inhibited to a certain extent, thanks to
the presence of ethylene oxide groups in the anionic species. The conditions for synergism in γcmc, differently expressed in the literature, can be derived from the surface tension equations established in our previous article.
They can be conveniently described by a few characteristic constants: Γ
i
∞ (saturated Gibbs excess), K
i
(constant in the Szyszkowski equation), the cmc of the individual surfactants and the interaction parameters, βS and βM, of their mixtures. Excellent agreement between theoretically predicted and experimental results is obtained. With the increase
in surfactant chain length, the βM values decrease faster than the βS ones and this can result in the loss of synergism in γcmc.
Received: 11 June 2000 Accepted: 4 September 2000 相似文献
65.
The specific features of the triplet-triplet (T-T) transfer of electronic excitation energy in a gas phase upon nonequilibrium
vibrational excitation of the triplet molecules of a donor were studied for an anthraquinone-diacetyl donor-acceptor pair
using the time-resolved slow fluoresence of anthraquinone and sensitized phosphorescence of diacetyl. It is shown that in
the gas phase, which allows regular control of the number of collisions, competition between the processes of T-T transfer
and intermolecular vibrational relaxation is observed for nanosecond time resolution. The T-T transfer rate for the molecular
system investigated exceeded the rate of intermolecular vibrational relaxation kV in the triplet state T1 of the donor. The effectiveness of the T-T transfer of energy by vibrationally excited molecules turned out to be higher
than the effectiveness of transfer by thermalized ones, but even the highest of them was much less than unity. An increase
in the equilibrium temperature of vapors led to a decrease in the effectiveness of transfer for both vibrationally excited
and thermalized triplet molecules, thus indicating the importance of the collisional complex in the intermolecular process
studied.
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 67, No. 4, pp. 474–479, July–August, 2000. 相似文献
66.
Feven Mattews Michael Mohammad Khalid Gunasunderi Raju Chantara Thevy Ratnam Rashmi Walvekar Nabisab Mujawar Mubarak 《Molecules (Basel, Switzerland)》2021,26(19)
We studied the reinforcing effects of treated and untreated nanohydroxyapatite (NHA) on poly-lactic acid (PLA). The NHA surface was treated with three different types of chemicals; 3-aminopropyl triethoxysilane (APTES), sodium n-dodecyl sulfate (SDS) and polyethylenimine (PEI). The nanocomposite samples were prepared using melt mixing techniques by blending 5 wt% untreated NHA and 5 wt% surface-treated NHA (mNHA). Based on the FESEM images, the interfacial adhesion between the mNHA filler and PLA matrix was improved upon surface treatment in the order of mNHA (APTES) > mNHA (SDS) > mNHA (PEI). As a result, the PLA-5wt%mNHA (APTES) nanocomposite showed increased viscoelastic properties such as storage modulus, damping parameter, and creep permanent deformation compared to pure PLA. Similarly, PLA-5wt%mNHA (APTES) thermal properties improved, attaining higher Tc and Tm than pure PLA, reflecting the enhanced nucleating effect of the mNHA (APTES) filler. 相似文献
67.
68.
This paper deals with an unreliable manufacturing system in which no backlog is allowed. The hedging point policy is used to control production. This paper's objective is to find the optimum hedging point so as to minimize the average inventory cost. Firstly, for a tentative hedging point, we derive the limiting distribution of the inventory level. This derivation is accomplished by comparison between this system and a finite storage-production system. Based on it we calculate the average inventory cost and find the optimum hedging point.This research was supported in part by the National Natural Science Foundation of China. Bin Liu was partially supported by ITDC, contract No. 105-82150. 相似文献
69.
70.
基于修正的Clough-Penzien地震动模型时MTMD的动力特性 总被引:3,自引:0,他引:3
研究了由许多刚度和阻尼保持常量而频率呈线性分布的TMD形成的MTMD的地震特性,基于虚拟激励法和本文提出的平稳过滤有色噪声地震动模型(修正的Clough-Penzien地震动模型),建立了结构-MTMD系统的传递函数,进而导出了设置MTMD时结构的动力放大系数(DMF)明确表达式。MTMD的优化准则可选为最大动力放大系数的最小值的最小化(Min.Min.Max.DMF)。通过最优搜寻可得MTMD的最优频率间隔、平均阻尼比、调谐频率比和相应的无量纲控制有效性指标。考虑结构受控频率与场地土卓越频率比的不同取值和不同场地类型,研究了场地土卓越频率和场地类型对MTMD最优参数及有效性的影响。而且,为比较,基于Clogh-Penzien地震动模型和不考虑地震动模型的结果也被考虑。 相似文献