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61.
制革工业污泥中Cr~(3+)的回收试验 总被引:3,自引:0,他引:3
对制革工业污泥中Cr回收与再利用进行了试验。试验表明:Cr的总回收率的高低主要决定于Cr3+的氧化是否彻底,在n(H2O2):n(Cr3+)为7.5,pH=10,温度为60℃以及反应时间为30min的条件下,污泥中Cr3+氧化率接近90%,总回收率可以达到80%以上。 相似文献
62.
63.
针对高维数据导致的维数灾难问题,提出了一种基于面向分类准则的维数约简方法。所提准则使每个训练样本在特征空间中与同类样本尽可能接近,而与异类样本尽可能疏远。首先对每个训练样本定义同类样本加权平均距离和异类样本加权平均距离。然后基于上述两个概念分别定义总体同类距离和总体异类距离。以最小化总体同类距离和最大化总体异类距离为目的提出了面向分类的准则(Classification Oriented Criterion,COC)。最后,基于面向分类的准则推导出了一种新的维数约简方法。在公共人脸数据库ORL和Yale上的实验表明所提方法性能优于有代表性的维数约简方法。 相似文献
64.
Novel silica nanoboxes were prepared by controlled dealumination of Na-X and Ca-A type zeolites using ammonium hexafluorosilicate (AHFS). The silica-richer
the parent zeolite, the smaller the average pore size produced and the narrower the pore size distribution obtained. This
was due to the specific reactivity of the extracting agent with the zeolite framework aluminum atoms. High temperature calcination
of the dealuminated X-zeolite (ammonium form) resulted in mesoporous materials exhibiting an ink-bottle shape, a quite high
surface area (330 m2/g, no micropores), an average pore diameter of 4.5 nm with a quite narrow pore size distribution (± 1.0 nm) and finally,
a pore opening diameter of 3.9 nm. The latter was determined by using the nitrogen sorption isotherms (BET technique) and
related pore volume data. The sorption behavior also suggested the interconnecting character of the newly created nanoboxes. The periodicity of these nanoboxes throughout the mesoporous material was clearly shown by X-ray powder diffraction at very small angles.
These materials, herein called monomodal nanoboxes because of the absence of micropores in the structure, were also thermally stable. Incorporation of orthosilicate into the obtained silica nanoboxes, in accordance with the recently developed technique for
pore size engineering in zeolites, led to materials with smaller pore openings but having almost the same textural properties. Solid superacidic materials were prepared by incorporating a liquid superacid
(triflic acid or trifluoromethanesulfonic acid) into the silica nanoboxes using the wet impregnation technique. The maximum
triflic acid loading which did not significantly affect the mesoporous framework of the materials was 24 wt%. As a reference,
the maximum loading of less acidic sulfuric acid was slightly lower. All this showed the high chemical stability of the silica nanoboxes for supporting very acidic species. Temperature-programmed desorption using a combined DTA/TGA system
allowed the identification of the bound phases and some liquid phase of the loaded triflic acid. 相似文献
65.
氧化铝生产赤泥附液吸收H_2S实验研究 总被引:1,自引:0,他引:1
对氧化铝生产附产赤泥吸收净化H2 S废气进行了实验研究 ,赤泥附液吸收H2 S具有吸收效率高、吸收容量大、易控制 ,操作简便等优点 ,在较少时间内对H2 S的吸收效率保持在 90 %以上。 相似文献
66.
张燕 《数码设计:surface》2014,(4):159-161
金州龙舞是国家级非物质文化遗产,是一种很具特色的民间艺术形式。文章追溯了金州龙舞的历史渊源,阐述了它的制作工艺,分析了它的品牌价值,提出了金州龙舞晶牌的保护与发展策略。 相似文献
67.
68.
Mei‐Rong Huang Sheng‐Xian Li Zhi‐Qing Dong Wei Feng Xin‐You Wang Shu‐Ying Gu Yan‐Hui Wu Xiang‐An Huang 《应用聚合物科学杂志》2002,83(14):3013-3021
Several multilayer thin low‐density polyethylene (LDPE) films were fabricated by blown thin film having a thickness of 7 μm and an area of 130 cm2. They were characterized for their oxygen‐enrichment performance from air by a constant pressure–variable volume method in a round permeate cell with an effective area of 73.9 cm2. The relationship between oxygen‐enrichment properties, including oxygen‐enriched air (OEA) flux, oxygen concentration, permeability coefficients of OEA, oxygen, nitrogen, as well as separation factor through the multilayer LDPE films, and operating parameters, including transfilm pressure difference, retentate/permeate flux ratio, temperature, as well as layer number, are all discussed in detail. It is found that all of the preceding oxygen‐enrichment parameters increase continuously with an increase of transfilm pressure difference from 0.1 to 0.65 MPa, especially for the trilayer and tetralayer LDPE films. The oxygen concentration and separation factor appear to rapidly increase within the retentate/permeate flux ratio below 200, and then become unchangeable beyond that, whereas the OEA flux and the permeability coefficients of OEA, oxygen, and nitrogen seem to remain nearly constant within the whole retentate/permeate flux ratio investigated, especially for the monolayer and bilayer LDPE films. The selectivity becomes inferior, whereas the permeability becomes superior, as the operating temperature increases from 23 to 31°C. The highest oxygen concentration was found to be 44.8% for monolayer LDPE film in a single step with air containing oxygen of 20.9% as a feed gas and operating pressure of 0.5 MPa at a retentate/permeate flux ratio of 340 and 23°C. The results demonstrate a possibility to prepare an oxygen‐enriching membrane directly from air, based on the easily obtained thin LDPE films. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 3013–3021, 2002; DOI 10.1002/app.2331 相似文献
69.
以工程实例为依据,论述国内以往较少采用的大型梁柱式支承锥顶贮罐的结构,介绍了国内外相关设计标准,给出了贮罐的典型结构-斜椽,横梁和立柱的计算公式,并用Excel电子表格编制了计算书。 相似文献
70.
Many rate constants of elementary steps on single crystals have been measured. Their pre-exponential factors can now be compared to those calculated by transition state theory. Such a calculation is presented in this Letter with due attention to microscopic reversibility, standard states, and configurational entropy. 相似文献