Biodegradation of lipids from olive oil mill wastewaters in a stationary basket bioreactor with immobilized Bacillus spp. cells - influence of internal diffusion

The study is focused on the external and internal mass transfers of lipids during their biodegradation process in a bioreactor with stationary basket bed of immobilized Bacillus spp. cells. By means of the lipid mass balance for a single particle of biocatalyst, considering the kinetic model adapted for the immobilized bacterial cells, specific mathematical models have been developed to estimate their mass flows in the liquid boundary layer surrounding the particle and inside the particle. The values of mass flows are significantly influenced by the internal diffusion velocity of lipids and the rate of their consumption, but also by the position inside the basket bed. These influences accumulated led to the appearance of a biological inactive region near the particle centre, its magnitude varying from 1.3 to 49.4% of the overall volume of particles.     

Neural computing models for prediction of permeability coefficient of coarse-grained soils

Correlations are very significant from the earliest days; in some cases, it is essential as it is difficult to measure the amount directly, and in other cases it is desirable to ascertain the results with other tests through correlations. Soft computing techniques are now being used as alternate statistical tool, and new techniques such as artificial neural networks, fuzzy inference systems, genetic algorithms, and their hybrids were employed for developing the predictive models to estimate the needed parameters, in the recent years. Determination of permeability coefficient (k) of soils is very important for the definition of hydraulic conductivity and is difficult, expensive, time-consuming, and involves destructive tests. In this paper, use of some soft computing techniques such as ANNs (MLP, RBF, etc.) and ANFIS (adaptive neuro-fuzzy inference system) for prediction of permeability of coarse-grained soils was described and compared. As a result of this paper, it was obtained that the all constructed soft computing models exhibited high performance for predicting k. In order to predict the permeability coefficient, ANN models having three inputs, one output were applied successfully and exhibited reliable predictions. However, all four different algorithms of ANN have almost the same prediction capability, and accuracy of MLP was relatively higher than RBF models. The ANFIS model for prediction of permeability coefficient revealed the most reliable prediction when compared with the ANN models, and the use of soft computing techniques will provide new approaches and methodologies in prediction of some parameters in soil mechanics.     

Temperature stability of thin anodic oxide films in metal/insulator/metal structures: A comparison between tantalum and aluminium oxide

The dielectric breakdown of thin (d = 3–4 nm) aluminium and tantalum oxide films was investigated by means of current voltage plots in metal/insulator/metal systems. Dielectric breakdown field strengths, E_DB, of 0.6 GV m^− 1 were found for both oxide types at room temperature. Differences appear in the temperature dependence of E_DB. Tantalum oxide films show an unchanged breakdown behaviour for temperatures up to 420 K while aluminium oxide films lose already 80% of their E_DB value in the same temperature range. Time-resolved investigations of the electric breakdown revealed intermediate states of both oxide types which were stable for several ms being characterized by an enhanced tunnel current. The breakdown voltage clearly scales with the oxide thickness for both oxide types.     

Pulsed laser deposition of La0.67Ca0.33MnO3 thin films on LiNbO3 and surface acoustic wave studies

Surface Acoustic Waves on piezoelectric substrates can be used to investigate the dynamic conductivity of thin films in a non-contact and very sensitive way, especially at low conductivities. Here, we report on such surface acoustic wave studies to characterize thin manganite film like La_0.67Ca_0.33MnO₃, exhibiting a Jan Teller effect with a strong electron phonon interaction and a metal insulator transition at high temperatures.

We report on the deposition of La_0.67Ca_0.33MnO₃ on piezoelectric substrates (LiNbO₃ in different crystal cuts, employing a pulsed laser deposition technique. The structural quality of the thin films are examined by X-Ray Diffraction, Scanning Electron Microscope and Energy Dispersive X-ray spectroscopy. For the electrical characterization, we employ the surface acoustic wave technique, accompanied by conventional direct current resistance measurements for comparison.     

Polyol method for the preparation of nanosized Gd2O3, boehmite and other oxides

A modified microwave-assisted polyol method was applied to prepare nanoparticulate ceramic powders of different oxides, i.e. Gd₂O₃, AlO(OH) (boehmite) and TiO₂. Due to the good dielectric properties of the utilised solvents, such as ethylene glycol, diethylene glycol and 1,4 butanediol, a significant decrease in reaction time was achieved under microwave heating. In the case of AlO(OH) and Gd₂O₃, <5 nm primary particle size were obtained. Boehmite was found to be intercalated with the solvent. The general applicability of the process is shown and the advantages in terms of properties and processibility are described. The powders thus prepared were investigated using X-ray diffractometry, electron microscopy and physisorption.     

SnO2 纳米传感器的灵敏度􀀁温度特性曲线拟合研究

对三次样条函数在纳米传感器输出特性曲线拟合中的应用进行了理论分析,应用软件Matlab6.5结合实验数据对掺杂苯的SnO2纳米传感器的灵敏度-温度特性曲线进行了拟合,结果表明三次样条曲线函数的拟合曲线光滑且精度高,相对误差在-0.2%～ 0.3%以内.     

解耦的声表面波波动方程的求解􀀂

由于压电材料对称性的存在,当一些压电材料取某些特殊切型时,声表面波存在着解耦现象,解耦波常有几种固定的模式.本文对解耦的声表面波波动方程的求解进行了研究.并以PZT-5H材料为例,用编制的程序对解耦的纯Rayleigh波和B-G波进行了计算机数值求解,其结果与文献[3]的值一致.说明这一求解原理和方法普遍适用于对各种解耦的声表面波波动方程的求解.对于全面分析SAW的传播特性具有一定的参考价值.     

多传感器检测系统的 多步反馈融合算法

通过分析分布式检测系统的工作原理，提出了一种新的局部检测器融合方法，该方法利用检测器局部判决结果与融合中心融合结果的误差多步累积平均值对检测器下一步判决进行修正，从而达到提高检测器检测概率的目的。分析表明，该算法能有效提高系统的性能。     

基于BSLA 最小二乘法的多功能传感器信号重构

最小二乘技术经常在利用若干测量数据评估被测变量的情况中使用，当使用这种方法来获得一个最佳线性逼近空间(BSLA)时，就会建立一个能够处理冗余度量数据的最佳解决方案，从而改善在三维空间环境中信号重构的效果(通常情况下，多功能传感器都是三元或三元以上的度量函数)。为此提出了一种应用最小二乘算法重构多功能传感器被测信号的方法验证其有效性，建立了仿真模拟电路，并给出了仿真结果和算法误差分析。