内填充农作物秸秆的粉煤灰砌块保温墙体热工性能研究

利用秸秆导热系数较小的特性,制备保温性能较好的内填充农作物秸秆的粉煤灰砌块.通过试验确定了秸秆与石膏合理的掺配比例,并测试了内填农作物秸秆的粉煤灰砌块保温墙体的热工性能.结果表明,将m(玉米秸秆):m(石膏)=1:2.5的玉米秆粉料填充到粉煤灰空心砌块内制作的保温墙体传热系数仅为0.988 W/(m2·K),与加气混凝土砌块墙体的传热系数相近,大幅度地提高了墙体的保温性能.     

Development of a mechanistic model for biological nutrient removal activated sludge systems and application to a full‐scale WWTP

In wastewater treatment plants (WWTPs) the production of nitrite as an intermediate in the biological nutrient removal (BNR) process has been widely observed, but not been taken into account by most of the conventional activated sludge models yet. This work aims to develop a mechanistic mathematical model to evaluate the BNR process after resolving such a problem. A mathematical model is developed based on the Activated Sludge Model No.3 (ASM3) and the EAWAG Bio‐P model with an incorporation of the two‐step nitrification–denitrification, the anoxic P uptake, and the associated two‐step denitrification by phosphorus accumulating organisms. The database used for simulations originates from a full‐scale BNR municipal wastewater treatment plant. The influent wastewater composition is characterized using batch tests. Model predictions are compared with the measured concentrations of chemical oxygen demand (COD), NH‐N, NO‐N, NO‐N, PO‐P, and mixed liquid volatile suspended solids. Simulation results indicate that the calibrated model is capable of predicting the microbial growth, COD removal, nitrification and denitrification, as well as aerobic and anoxic P removal. Thus, this model can be used to evaluate and simulate full‐scale BNR activated sludge WWTPs. © 2009 American Institute of Chemical Engineers AIChE J, 2009     

陶瓷滑动轴承磨损可靠性建模及仿真分析

以一种全Al₂O₃陶瓷滑动轴承为研究对象,基于Evans陶瓷磨损失效模型和轴承几何模型,建立陶瓷滑动轴承的磨损深度函数模型,并编制MatLab仿真程序确定磨损深度概率分布函数。使用所建立磨损深度函数模型一阶原点矩及二阶中心矩结合数值积分法建立陶瓷轴承磨损可靠度模型,并使用Monte Carlo可靠度仿真方法进行验证。根据磨损可靠度计算与仿真结果,分析不同参数对可靠度的影响,结果表明：可靠度随工作时长、载荷、转速的增加而减小,随轴瓦长度增加而增大,且可靠度曲线都呈现出初期变化平缓,随后快速变化,最后再次趋于平缓的趋势。     

软弱地基条件下的大型燃机机座基础施工

江苏华电望亭发电厂1~#、2~#燃机基础为国内长宽比最大的狭长型大体积混凝土基础,其长93.62m、宽10.4m、厚3.0m,基桩为φ600mm×110mm、长27mPHC桩。为达到国外设计公司的要求,施工中采用了相对应的质量保证措施,取得了理想的效果。     

Controlled oscillations in chain of unidirectionally coupled bistable oscillators with chaotic dynamics

Equations of a chain of n (n = 1, 2, ...) unidirectionally coupled bistable oscillators possessing chaotic dynamics are presented. Numerical analysis has been performed for a system of three identical autooscillatory systems with nonlinear elements admitting cubic approximation. It is shown that, as the degree of coupling between units in the chain increases, their motions in the phase space become more complicated and even chaotization of oscillations may take place at the parameters with which separate oscillators exhibit regular motions in the autonomous regimes. The features of the influence of a driving oscillator on the motions of a driven bistable subsystem are related to filtration of the driving signal in the circuit of the driven subsystem.     

SF_6断路器灭弧室内三维电场数值模拟

运用有限元法FEM对罐式SF6断路器断口附近三维电场进行了数值计算 ,以计算机辅助绘图为支撑 ,完成了SF6断路器三维电场的数值模拟。在三维电场数学模型的建立中考虑了屏蔽罩和并联电容器组的存在 ;对断路器不同三维剖面的等电位线分布及电场分布情况进行了分析 ;并将计算结果进行三维图形可视化处理及显示。     

Chaotic dynamics of oscillator based on lossless circuit

Equations that describe a new autooscillatory system with chaotic dynamics based on a lossless oscillatory circuit are presented. This system is capable of generating chaotic oscillations with irregular variations in the amplitude (amplitude chaos) at a small change in frequency. Bifurcation diagrams (one- and two-parametric), time series of the oscillatory process, and power spectra of the proposed system are presented.     

Synthesis and structure study of copolymers from thiadiazole fused indolocarbazole and dithienosilole

We report synthesis and characterization of two D-A polymers (PSDT-C12 and PSDT-EH) with different side chains. Both polymers are based on alternate 12,13-dioctyl-indolo[2,3-a][1,2,5]thiadiazolo[3,4-c]carbazole (TDZIC) and dithienosilole derivative units in polymer main chain. We used TDZIC to enlarge the 2D conjugated plane of acceptor monomers by fusing benzothiadiazole (BT) unit with an indole unit having alkyl groups. PSDT-C12 exhibited 10 nm redshift compared to PSDT-EH in solid films, while their absorption spectra were almost identical in solutions. Since the backbone and side chains on the indolocarbazole group are the same, the redshift on PSDT-C12 could be resulted from the dodecyl (C12) side chain on the dithienosilole unit and different molecular weight between these two polymers. PSDT-C12 has a larger molecular weight than PSDT-EH. Therefore possibly both side chains and molecular weight contributed to the difference in the absorption spectra in solid films. The straight C-12 side chain has less steric hindrance than the branched EH side chain in solid films. PSDT-C12 has a longer main chain (larger molecule weight) than PSDT-EH, which can favour a more extended main chain interaction. The vibronic peak at 519 nm and shoulder at 563 nm in the PSDT-C12 film further confirmed stronger main chain interaction. Geometry optimization showed that head–tail (HT)-PSDT had a more twisting conjugated backbone with larger dihedral angle between dithienosilole unit and thiadiazole-fused ring compared to head–head/tail–tail (HH/TT)-PSDT.     

Image enhancement via space-adaptive lifting scheme exploiting subband dependency

This paper proposes an image enhancement method based on space-adaptive, 2-D lifting scheme. In the space-adaptive update-first lifting scheme, the prediction stage is adapted to the signal structure point-by-point which results in a better signal representation and enhancement result. In this paper, a novel edge-sensitive adaptive prediction method is introduced in the 2-D lifting framework. The method adaptively chooses the best predictor among a set of predictors minimizing the prediction error. The proposed prediction method is sensitive to both even and odd indexed edge pixels in the 2-D lifting context. The bivariate shrinkage which assumes the dependence of the subband wavelet coefficients is used for subband image enhancement. As an objective quality measure, the peak signal-to-noise ratio test is applied to the results of the proposed image enhancement algorithm. Results of the proposed algorithm are compared with those of the VisuShrink, BayesShrink, and NorShrink. Experimental and objective quality test results prove the superior performance of the proposed image enhancement method.     

Experimental study of useful signal separation from pulse-modulated fluctuation noise in application to hidden data transmission

Hidden data transmission at microwave frequencies has been experimentally carried out by masking the useful signal with a continuous random signal of the new type formed from two series of identical fluctuation-noise-carried pulses that are delayed relative to each other by a time equal to the pulse duration.