灰色系统理论在垃圾填埋场稳定化研究中的应用

灰色系统理论在填埋场稳定化分析中有一定的价值。论文就稳定化因素分析运用层次分析法及灰色关联度法得到相同的结论,渗滤液回灌(产生量)对填埋场的稳定化影响最显著。进而在稳定化分析中选取沉降这一评价因子进行了研究。     

Composite beam composed of steel and precast concrete (Modularized Hybrid System,MHS). Part I: experimental investigation

An experimental investigation of composite beams composed of wide flange steel and precast concrete is presented. The bottom flange of the steel section is encased in precast concrete. Utilizing the merits of both steel and concrete material, the size of the steel beams can be reduced without sacrificing performance. The bottom flange of the steel beam is reinforced with concrete at a manufacturing plant, eliminating the use of temporary pour forms. The composite beams were tested to investigate how the size of the wide flange steel and how the top and bottom reinforcements influence the behaviour of the beams. Flexural load carrying capacity, load displacement relationships and failure modes were examined. The test specimens were T‐shaped composite beams with slabs, each measuring 10‐m long. The flexural moment strength of all of the composite beams—at both the yield limit state and the maximum load limit state—was measured and compared with the analytical flexural capacity. The stiffness degradation, ductility and dissipating energy capabilities of the composite beams were investigated based on the hysteresis curves. The composite beams tested in this study successfully reduced both the floor height of the building and the size of the steel beams needed to meet code requirements. Copyright © 2008 John Wiley & Sons, Ltd.     

Elucidation and short-term forecasting of microcystin concentrations in Lake Suwa (Japan) by means of artificial neural networks and evolutionary algorithms

Non-supervised artificial neural networks (ANN) and hybrid evolutionary algorithms (EA) were applied to analyse and model 12 years of limnological time-series data of the shallow hypertrophic Lake Suwa in Japan. The results have improved understanding of relationships between changing microcystin concentrations, Microcystis species abundances and annual rainfall intensity. The data analysis by non-supervised ANN revealed that total Microcystis abundance and extra-cellular microcystin concentrations in typical dry years are much higher than those in typical wet years. It also showed that high microcystin concentrations in dry years coincided with the dominance of the toxic Microcystis viridis whilst in typical wet years non-toxic Microcystis ichthyoblabe were dominant. Hybrid EA were used to discover rule sets to explain and forecast the occurrence of high microcystin concentrations in relation to water quality and climate conditions. The results facilitated early warning by 3-days-ahead forecasting of microcystin concentrations based on limnological and meteorological input data, achieving an r(2)=0.74 for testing.     

炭黑N339在全钢载重子午线轮胎胎面胶中的应用

研究炭黑N339在全钢载重子午线轮胎胎面胶中的应用。结果表明：与加入52份炭黑N220的胶料相比,采用炭黑N339替代50%或全部替代炭黑N220的胶料的硫化速率增大,硫化胶的硬度和300%定伸应力增大,压缩生热分别减小3.8和4.5 ℃,耐磨性能提高;当炭黑N339和炭黑N220用量比为1/1时,硫化胶的滚动阻力低、动态生热小,成品轮胎的耐久性能优异,高速性能相当。     

Analysis of "total toxaphene" and selected single congeners in biota by ion trap HRGC-EI-MS/MS using congener-optimized parent ion dissociations

A method for the quantification of selected toxaphene congeners as well as "total toxaphene" was developed based on electron ionization (EI) tandem (MS/MS) ion trap mass spectrometry (MS) and a combination of fragment ion dissociations. Congeners were separated by high-resolution gas chromatography. Compared to conventional EI low-resolution MS, a 5-20-fold gain in sensitivity could be obtained for octa- or nonachlorinated compounds such as toxaphene #26 and #62 (according to Parlar nomenclature), allowing for their detection in the low picogram range in biota. In addition, response factors for important congeners such as #26, #32, #40/41, #42, #44, #50, and #62 deviated not more than a factor of 2, which is much less as compared to negative ion chemical ionization. This reduces the risk for systematic errors when determining total toxaphene on the basis of a limited number of reference compounds or the technical mixture. Furthermore, chlordanes and polychlorinated biphenyls did not interfere when applying the proposed MS/MS technique. The applicability of the method was tested by determining both total toxaphene and levels of selected congeners in six Arctic wildlife samples collected from Nunavut, Canada, as well as by repetitive analyses of the SRM 1588 certified reference material.     

Comparison of alginate and pectin based beads for production of poultry probiotic cells

A comparative study on the stability and potential of alginate and pectin based beads for production of poultry probiotic cells using MRS medium in repeated batch fermentation was conducted. The bead cores, made of three types of materials, i.e., ca-alginate, ca-pectinate and ca-alginate/pectinate, were compared. The effect of single and double layer coatings using chitosan and core material, respectively, on the bead stability and cell production were also studied. The pectin based beads were found to be more stable than that of the alginate beads and their stability was further improved by coating with chitosan. The cell concentration in pectin based beads was comparable to that in the alginate beads. On the other hand, pectin based beads gave significantly lower cell concentration in the growth medium for the initial fermentation cycles when compared to the alginate beads. In conclusion, pectin was found to be potential encapsulation material for probiotic cell production owing to its stability and favourable microenvironment for cell growth.     

Reaction Delay of Aluminum in Condensed Explosives

A universal empirical relation is derived to predict the reaction delay times of aluminum particles as a function of particle diameter and gas temperature in explosives. The predicted delay times are shown to be in reasonable agreement with experimental data obtained in both low temperature and high temperature explosives. A convective heat transfer model is used to estimate the surface temperature of the solid aluminum particles. The reaction delay time of aluminum is shown to be close to the time when the particle surface reaches the pressure dependent melting point of aluminum.     

Survey of ochratoxin A and deoxynivalenol in stored grains from the 1999 harvest in the UK

Three hundred and twenty samples from the 1999 UK harvest comprising wheat (201 samples), barley (106) and oats (13) were analysed for ochratoxin A and deoxynivalenol. A small number of organic samples was also obtained. Samples were collected from farms, central stores, mills, maltings and ports from across the UK from February to April 2000. Ochratoxin A and deoxynivalenol analysis was by affinity column clean up and high-performance liquid chromatography with fluorescence and ultraviolet light detection, respectively, with limits of detection of 0.2 and 20 μg kg^-1. The survey found ochratoxin A at below 5 μg kg^-1 in 97% of the samples indicating satisfactory storage conditions. The remaining 3% of the samples contained ochratoxin A at levels between 5.2 and 231 μg kg^-1, but none of these samples was intended for human consumption. Deoxynivalenol was detected in 88% of all samples, with 83% below 100 μg kg^-1; the maximum level was 600 μg kg^-1. Twenty samples containing deoxynivalenol at or above 150 μg kg^-1 by high-performance liquid chromatography were all confirmed by gas chromatography/mass spectrometry. Nivalenol was also detected by gas chromatography/mass spectrometry at levels of 50 μg kg^-1 or higher in 18 of 20 samples where deoxynivalenol was confirmed.     

数控喷涂机伺服进给系统的设计与研究

介绍一种适合高速轻载的直线进给系统的结构形式。通过对数控喷涂机横向进给系统的设计研究，并对同步带直接驱动单元的结构形式和特点的分析，得出一种适于高速轻载的直线进给系统的驱动方式。