Application of artificial neural networks to the analysis of two‐dimensional fluorescence spectra in recombinant E coli fermentation processes

A two‐dimensional (2D) spectrofluorometer was used to monitor various fermentation processes with recombinant E coli for the production of 5‐aminolevulinic acid (ALA). The whole fluorescence spectral data obtained during a process were analyzed using artificial neural networks, ie self‐organizing map (SOM) and feedforward backpropagation neural network (BPNN). The SOM‐based classification of the whole spectral data has made it possible to qualitatively associate some process parameters with the normalized weights and variances, and to select some useful combinations of excitation and emission wavelengths. Based on the classified fluorescence spectra a supervised BPNN algorithm was used to predict some of the process parameters. It was also shown that the BPNN models could elucidate some sections of the process's performance, eg forecasting the process's performance. Copyright © 2005 Society of Chemical Industry     

An online technique for monitoring the insulation condition of AC machine stator windings

A novel online technique for monitoring the insulation condition of ac machine stator windings is proposed in this paper. The concept is to measure the differential leakage currents of each phase winding from the terminal box in a noninvasive manner to assess the insulation condition during motor operation. The conventional differential CTs used for phase fault protection can be replaced with high performance current sensors to measure the leakage current with higher accuracy. Indicators for insulation condition such as the capacitance and dissipation factor are calculated based on the measurements to provide a low cost solution for online insulation condition assessment. A simplified online insulation system model is derived for analysis and interpretation of the measured data. Experimental results on a 15-hp induction motor under simulated insulation degradation conditions show that the proposed technique is a very sensitive method capable of detecting incipient signs of insulation degradation.     

Evaluation of recursive queries with extended rules in deductivedatabases

In order to extend the expressive power of deductive databases, a formula that can have existential quantifiers in prenex normal form in a restricted way is defined as an extended rule. With the extended rule, we can easily define a virtual view that requires a division operation of relational algebra to evaluate. The paper addresses a recursive query evaluation where at least one formula in a recursive rule set is of an extended rule. We investigate transformable recursions as well as four cases of non-transformable recursions of transitive-closure-like and linear type. The work reveals that occurrence of an existentially quantified variable in the extended recursive body predicate might dramatically limit the level of recursive search. In particular, the number of iterations to answer extended queries can be determined, independently of database contents     

Construction of efficient error-limiting variable length codes

A novel method for generating an optimal binary prefix condition code is described. The proposed code generation method generates optimal variable length codes that have short average error spans compared to the existing self-synchronising codes. A technique for calculating the expected error spans of variable length codes are also presented     

Prolonged systemic and regional haemodynamic effects of intracerebroventricular angiotensin II in conscious sheep

1. The haemodynamic mechanisms by which infusion of angiotensin II (AngII), either into the lateral cerebral ventricles (i.c.v.) or intravenously (i.v.), increased arterial pressure were studied in conscious sheep. 2. Sheep were previously fitted with flow probes for measurement of cardiac output and coronary, mesenteric, renal and iliac blood flows. 3. Intracerebroventricular AngII (10 nmol/h for 1 h) increased arterial pressure by 11 +/- 4 mmHg (P < 0.001) due to vasoconstriction, predominantly in the mesentric vasculature. These effects developed over 30 min and took 2 h to return to control. Following the infusion renal conductance increased continuously for 3 h, resulting in a parallel increase in renal blood flow (to 75 +/- 18 mL/min above control, P < 0.001). 4. Intracerebroventricular AngII increased plasma vasopressin from 0.8 +/- 0.3 to 7.2 +/- 1.8 pg/mL (P, 0.01), and reduced plasma renin concentration from 0.9 +/- 0.3 to < 0.4 nmol/L/h. 5. The pressor effect of i.v. AngII (5, 10, 25, 50 nmol/h) also depended on peripheral vasoconstriction, but the pattern of responses was different. The greatest degree of vasoconstriction occurred in the renal, followed by the mesentric and iliac vascular beds; these effects were rapid in onset and offset. 6. In conclusion, the pressor responses to both i.c.v. and i.v. angiotensin depended on peripheral vasoconstriction, but there were contrasting regional haemodynamic changes. ICV AngII caused a prolonged pressor response, mainly due to mesentric vasoconstriction possibly partly due to vasopressin release, and following the infusion there was a pronounced, long-lasting renal vasodilatation. In contrast, i.v. AngII caused vasoconstriction preferentially in the renal vascular bed and its effects were short lasting.     

Nicalon-fibre-reinforced silicon-carbide composites via polymer solution infiltration and chemical vapour infiltration

A new, faster process was developed for the fabrication of Nicalon-fibre-reinforced SiC composites by combining polymer solution infiltration (PSI) and chemical vapour infiltration (CVI). The process led to the near-net-shape fabrication of fibre-reinforced ceramic-matrix composites and reduced infiltration time. Typical flexural strength and fracture toughness of these composites were 296 MPa and 10.9 MPa m^1/2 at room temperature (RT) and 252 MPa and 9.6 MPa m^1/2 at 1000 °C, respectively. The composites exhibited load-carrying capability after crack initiation.     

正交试验法于优选白瓷坯料配方中的应用

对长石、石英、龙岩土、莱阳土４种因素各取４个水平，用正交表Ｌ１６（４５）安排１６个试验，分析了这１６个试验产品的吸水率、白度、热稳定性与每种因素各水平之间的关系．得出了白瓷坯料的最佳配方。其中，长石１９，石英２１，龙岩土２１．莱阳土０．