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The timetabling problem is concerned with the allocation, subject to constraints, of given resources to objects in space and time in such way as to satisfy as nearly as possible a set of desirable objectives. This problem is known to be NP–complete and as such only combinatorial optimization methods can guarantee an optimal timetable. In this paper we propose a sector–based genetic algorithm for solving a university weekly courses timetabling problem. Preliminary experimental results indicate that the algorithm is promising. 相似文献
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Ensemble of classifiers is a learning paradigm where many classifiers are jointly used to solve a problem. Research has shown that ensemble is very effective for classification tasks. Diversity and accuracy are two basic requirements for the ensemble creation. In this paper, we propose an ensemble creation method based on GA wrapper feature selection. Preliminary experimental results on real-world data show that the proposed method is promising, especially when the number of training data is limited. 相似文献
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以玉柴YC6K420LN-C31型柴油机为研究对象,基于RBF(radial basis function)神经网络算法建立发动机数据模型,采用PSO(particle swarm optimization)算法进行基于模型的多目标优化研究.研究表明:RBF神经网络建立的NOx、总碳氢化合物(THC)、CO和燃油消耗率(brake specific fuel consumption,BSFC)数据模型的决定系数R2分别为0.93、0.98、0.96和0.95,模型的预测准确度均大于90%,拟合优度和预测能力满足多目标优化的需求;采用PSO算法对发动机进行多 目标优化,将适应度目标NOx、THC、CO和BSFC的权重最终均设置为0.25,生成控制图谱并进行台架验证,在推进特性工况下总排放量和油耗相比于原机平均降低了 22.9%与5.3%. 相似文献
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天然气转化催化剂的失活特性 总被引:1,自引:2,他引:1
用化学分析、BET流动色谱法,X射线衍射及小角散射等方法,对天然气转化催化剂的失活特性进行研究,发现催化剂中Ni组分有流失现象,流失率约为10%左右;失活催化剂中有NiO、NiC等新物相存在,比表面积增大。与新鲜催化剂对比分析可知,作为载体的α-Al2O3,失活后在(012)和(104)晶面上平均晶粒度减小;Ni在(111)晶面上的晶粒度变化不大,但在晶面(200)上的晶粒度增大。失活催化剂的孔径分布改变较多,小孔的比率相对增加,而在孔径为25nm附近的过渡孔减少。 相似文献
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为了降低稀燃CNG发动机燃烧循环变动,设计了一种双线圈点火系统。利用Multisim软件仿真研究了新点火系统次级电压的变化规律,并在发动机台架上研究了此点火系统对CNG发动机燃烧稳定性的影响。次级电压的仿真结果表明,在不同放电间隔的条件下,新点火系统分别能够有效提高次级电压,增加火花持续期并能实现多次放电。台架试验表明,在合适的放电模式下新点火系统能够降低发动机的循环变动系数,提高稀燃CNG发动机燃烧稳定性。 相似文献
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