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391.
针对矿井瓦斯涌出量影响因素复杂,数据序列波动性较大,灰色GM(1,1)预测模型精度低,本身存在一定缺陷的特点,将自记忆性原理引人灰色系统理论,建立了矿井瓦斯涌出量预测的灰色自记忆预测模型。经在韩城下峪口煤矿应用表明,该模型具有预测精度高,稳定性好的特点。 相似文献
392.
The stabilization of severely As-polluted soil has been a challenge, especially for the extremely toxic As(Ⅲ) contaminants. In this study, soil with a high As concentration (26084 mg/kg) was availably stabilized by a H2O2 pre-oxidation assisted TMT-15 (Na3S3C3N3 solution with a mass fraction of 15%) and FeCl3·6H2O stabilization method. The results showed that the combination of the two stabilizers (i.e., TMT-15 and FeCl3·6H2O) presented a better stabilization behavior than either stabilizer used individually. The use of the H2O2 pre-oxidation assisted TMT-15 and FeCl3·6H2O stabilization approach not only converted the As(Ⅲ) to As(V) but also reduced the toxic leaching concentration of As to 1.61 mg/L, which is a safe level, when the additions of TMT-15 and FeCl3·6H2O were 2 mL and 0.20 g, respectively. Thus, using only a simple H2O2 pre-oxidation to combine clean stabilization with non-toxic stabilizers TMT-15 and FeCl3·6H2O could render the severely As-contaminated soil safe for disposal in a landfill. 相似文献
393.
b-NiAlDy cast alloys containing varying aluminum content were prepared by arcmelting.The microstructures and cyclic oxidation behavior of the alloys at 1200 1C wereinvestigated. Grain refinement was achieved by increasing aluminum content in the alloy, whichis beneficial to selective oxidation. The Ni–55Al–0.1Dy alloy showed excellent cyclic oxidationresistance due to the formation of a continuous, dense and slow-growing oxide scale. In contrast tothis, severe internal oxidation as well as large void formation at the scale/alloy interface occurred inthe Ni–45Al–0.1Dy alloy. The aluminum content dependence of the reactive element effects in b-NiAlDy was established that Dy doping strengthened the scale/alloy interface by peggingmechanism in high-aluminum alloys but accelerated internal oxidation in low-aluminum alloysduring high-temperature exposure. 相似文献
394.
The ordered ω phases in high Nb containing Ti Al(Nb-Ti Al) alloys have been garnering increasing attention in the recent years. However, the investigations on the Nb dependence on the ωoprecipitation are scarce. In this study, the effect of Nb content on the ωoprecipitation in high Nb(6–10 at%) containing Ti Al alloys after long-time annealing at 850 1C has been studied. The results show that small ordered ω particles in the retained βophase cannot be discerned under scanning electron microscope(SEM) but can be observed using transmission electron microscopy(TEM). Although the Nb segregation can be eliminated after the homogenization heat treatment, the ωophase precipitated in all the alloys studied after annealing at 850 1C. TEM examination reveals that the orientation relationship between the ωoand α2phases can be derived as: [0001]ωo//[1120]α2;(1120)ωo//(0001)α2, which indicates that the ωophase is directly transformed from the parent α2phase. Small γ particles are also observed within the ωoareas. The α2-ωot γ decomposition process is expected during annealing. It is concluded that ωophase is an equilibrium phase in high Nb-Ti Al alloys at 850 1C. 相似文献
395.
The density distribution and internal structure of trabecular bone are modulated by local mechanical environment. In this study, an orthotropic adaptation algorithm was applied to the 3D femur model to simulate the variations of stiffness and orientation of trabecular bone under multi-loading conditions. This algorithm includes the determination of orthotropic axes and the stiffness modification of trabecular bone. Three methods were used to determine the orthotropic axes, i.e. the maximal cycle method, the stress maximum method, and the composite method. We found that the composite method was better than the other two. Firstly, the characteristics of density distribution obtained by using the composite method agreed better with those in real proximal femur. Secondly, the material orientation aligned with the known trabeculaer pattern. Finally, the ratios of the longitudinal modulus to the transverse modulus were also shown to be realistic in three local regions of the proximal femur. 相似文献
396.
Peng Qiyou 《中国工程科学》2003,1(1):94-99
1AchievementsinCon structionofPhaseⅠTGPworks TheTGPConstructionCommitteeun dertheStateCouncilapprovedthePre liminaryDesignReportoftheYangtzeThreeGorgesProjectonJuly 31 ,1 993.whenTGPenteredaphaseofprepara tionsforconstructionandphaseⅠworks.Bytheendof1 997,theprojecthadprogressedsmoothlyandthetaskforPhase 1workshadbeencompleted ,whichwashighlightedbytheriverclo sureoftheGrandChannel,providingfullpreparationforPhase 2construc tion . ThededicatedaccessexpresswayandtheXilingYangtze… 相似文献
397.
In this paper, we reported a new type of high performance microwave-absorbing material, polyaniline/montmorillonite doped with dodecylbenzensulfonic acid (PAni-DBSA/MMT) nanocomposite. The microwave-absorbing properties of this nanocomposite were investigated for the frist time. The nanocomposites were synthesized from emulsion polymerization using dodecylbenzensulfonic acid (DBSA) as dopant and emulsifier. The structure of the nanocomposite was analyzed by X-ray diffraction(XRD) and FT-IR, and its results denoted that PAni-DBSA/MMT is a typical intercalative polymer/layered silicate(PLS) nanocomposite, and the interaction between MMT layers and PAni chains enhances the delocalization of free electrons in PAni chains. The complex permittivity, permeability and reflection loss (R.L.) of microwave of a 2.00 mm thick samples containing 50% by weight of PAni-DBSA/MMT nanocomposite and PANI?DBSA were measured, respectively, in 2?18 GHz range. The results showed that the PANI-DBSA/MMT nanocomposite is capable of absorbing 2.0?18 GHz microwaves, and the reflection loss was less than -10 dB in the frequency range of 9.1?12.5 GHz, while the minimum reflection loss was -15.8 dB at 11 GHz. The microwave absorbing mechanism of nanocomposite is disscused. 相似文献
398.
Peng Feng 《矿物冶金与材料学报》2003,10(4):61-64
The coherent-light-driven tunneling in double quantum wells has been studied. The electrons are coupled to a system of phonons and subjected to the two beams of coherently optical waves. By adopting a gauge to both the external field and the phonon field, the phonon field operators in the Schrodinger equations are eliminated. In this way, an expression of the tunneling current is conveniently derived considering the relaxation effect. It is shown that under the intense laser field, the tunneling current oscillates rapidly with time at low temperature. The duration of the oscillations is related to the temperature. By adjusting the phase difference of the two light-beams, the oscillation frequency can be modulated. 相似文献
399.
Applying the wavelet theory and methods to investigate the hydrologic processes such as precipitation and runoff is a hot field. However, several aspects in research are usually ignored: the effect of admissible condition of wavelet functions and the disturbance of noises for the detection of periods, the effect of the length of a hydrologic time-series on the final result, and the choice between the anomaly and the original time series for wavelet analysis. In this paper, these issues are fully discussed. Precipitation data from Lanzhou Precipitation Station are taken for case study. The result indicates that in the wavelet analysis of hydrologic series, denoise methods should be used to eliminate the influence of noises. The MexHat wavelet function satisfies the admissible condition, which ensures that the periodic properties of hydrologic processes can be well represented by using the MexHat wavelet for decomposition. The affected range of hydrologic series which should be discarded before analysis is given. It is also suggested that the anomaly series should be used to highlight the actual undulation of the hydrologic series. 相似文献
400.
AI Peng CHEN Liang HU Dehua CHEN Yanhua LU Dongshuang ZHANG Bao SHA Ke WANG Jingyuan 《科学通报(英文版)》2006,51(22):2706-2709
The hyperbranched aliphatic polyester P(e-CL) was synthesized by means of Novozyme435-catalyzed ring-opening polymerization (ROP) of BHB (2, 2-bis(hydroxymethyl) butyric acid). The chains ended with hydroxyl of P(e-CL) were modified by the esterification of a-bromopropionyl bromide to obtain hyperbranched difunctional macroinitiator, which was used in the ATRP of St. CuCI/HMTETA was used as the catalyst system in the reaction of ATRP to acquire the hyperbranched copolymers polystyrene-block-poly(2,2-bis(hydroxymethyl) butyric acid). The copoly-mer was confirmed by NMR and GPC. 相似文献