Combined erosion and corrosion of thermal sprayed WC and CrC coatings

This paper presents investigations of the combined effect of erosion and corrosion on one stainless steel and four different thermal sprayed coatings with carbide particles in a metal matrix. The materials were exposed to flowing synthetic sea water containing sand. Pure erosion, electrochemical corrosion and total material loss were determined at different sand concentrations. The effect of exposure time was also studied. The results show that erosion is the dominating process at high sand concentrations while corrosion is important at lower concentrations. The relative importance depends on the material. The corrosion resistance of the metal matrix has great influence on the total material loss rate. For the coating with lowest corrosion resistance there seems to be a synergistic effect between the mechanical and electrochemical processes.     

Test generation through logic programming

Utilization of the logic programming language Prolog in solving CAD/CAM/CAT problems is discussed. It is demonstrated through examples that, with Prolog, solutions are obtained through proper problem definition rather than by algorithmic procedures.The examples offered are in the area of test generation for digital circuits. A very simple formulation of the D-algorithm is presented, and it is demonstrated that levelling of the circuit is not necessary.Finally, we suggest other areas of CAD/CAM/CAT that may take advantage of logic programming.     

Food poisoning potential of Bacillus cereus strains from Norwegian dairies

Characteristics concerning diarrhoeal potential were investigated in B. cereus dairy strains. The thirty-nine strains, isolated from whipping cream, were tested for cytotoxicity after culturing at human body temperature as well as 25 degrees C and 32 degrees C. At 37 degrees C, none of the strains were highly cytotoxic. This observation suggests that those strains should be considered to pose a minor risk with regard to diarrhoeal food poisoning. However, some strains were moderately or highly cytotoxic when grown at 25 degrees C and 32 degrees C. While the majority of the strains were able to grow at refrigeration temperatures, only four B. weihenstephanensis strains were identified among them when subjected to discriminative PCR assays and growth temperatures which delimit this species.     

A feature selection method for multilevel mental fatigue EEG classification

Two feature selection approaches for multilevel mental fatigue electroencephalogram (EEG) classification are presented in this paper, in which random forest (RF) is combined with the heuristic initial feature ranking scheme (INIT) or with the recursive feature elimination scheme (RFE). In a "leave-one-proband-out" evaluation strategy, both feature selection approaches are evaluated on the recorded mental fatigue EEG time series data from 12 subjects (each for a 25-h duration) after initial feature extractions. The latter of the two approaches performs better both in classification performance and more importantly in feature reduction. RF with RFE achieved its lowest test error rate of 12.3% using 24 top-ranked features, whereas RF with INIT reached its lowest test error rate of 15.1% using 64 top-ranked features, compared to a test error rate of 22.1% using all 304 features. The results also show that 17 key features (out of 24 top-ranked features) are consistent between the subjects using RF with RFE, which is superior to the set of 64 features as determined by RF with INIT.     

油菜素甾醇类物的研究

油菜素甾醇类物是七十年代发现的一种活性极高的新型植物激素。从某些蜂蜡中提取的三十烷醇原粉里含有油菜素甾醇类物,并具有明显的、稳定的生物活性。     

基于瓦斯地质预测的地质量化技术

通过瓦斯地质分析,提出煤层围岩透气性、断层复杂程度、褶皱变形复杂程度、煤层倾角复杂程度、顶板岩性、构造煤发育程度的量化方法和计算公式。采用因子分析方法对陶二煤矿2煤层影响瓦斯涌出的瓦斯地质指标进行筛选,确定出3个主因子,建立了瓦斯涌出量预测模型,经过理论和实践验证,模型精度较高,可以用于未采区瓦斯涌出预测。     

转炉煤气管道及其附属设施存在问题的原因分析

结合转炉煤气管道及其附属设施普查中查出的问题,分析了转炉煤气管道及其附属设施内壁CO2腐蚀、管道排水管和排水槽腐蚀、漏泄等问题产生的原因,制定了相应的预防和整改措施.     

Load case reduction for offshore wind turbine support structure fatigue assessment by importance sampling with two‐stage filtering

A complete fatigue assessment for operational conditions for offshore wind turbines involves simulating thousands of environmental states. For applications such as optimization, where this assessment needs to be repeated many times, that presents a significant computational problem. Here, we propose a novel way of reducing the number of simulated environmental states (load cases) while maintaining an acceptable accuracy. From one full fatigue analysis of a base design, the OC3 monopile (with the NREL 5MW turbine), the distribution of fatigue damage per load case can be used to estimate the lifetime fatigue damage of a range of modified designs. Using importance sampling and a specially adapted two‐stage filtering procedure, we obtain pseudo‐optimal sets of load cases from which the fatigue damage is estimated. This is applied to seven different designs that have been modified to emulate iterations of an optimization loop. For several of these designs, sampling less than 1% of all load cases can give damage estimates with median errors of less than 2%. Even for the most severe cases, using 3% of the environmental states yields a maximum error of 10%. While further refinement is possible, the method is considered viable for applications within design optimization and preliminary design.