一种改进的多学习教与学优化算法

针对传统教与学算法在解决复杂多峰函数优化问题时,具有局部最优且搜索开发能力较差的缺点,提出了一种改进的多学习教与学优化算法,新算法为学员的每一维加入不同的教学因子,设计了基于学员均值比较的教师选择策略和向教师及学员学习的多学习策略。基于多个单峰和多峰函数的仿真结果表明,新算法跟传统的、改进的教与学算法相比,在稳定性、寻优精度和收敛速度方面更具优势。     

Fate of Co at a sludge land application site

Vertical distributions of ⁶⁰Co are determined in soil cores obtained from a 10-ha grassland, where anaerobically digested sludge was applied by surface spraying from 1986 to 1995 on the U.S. Department of Energy's Oak Ridge Reservation. These results, along with historical application records, are used to estimate vertical-migration rates and perform a mass balance. The presence of ⁶⁰Co results solely from the sludge-application process. Soil, vegetation, and surface-water samples were collected. Eleven soil cores were sectioned into 3-cm increments and analyzed by gamma-ray spectrometry. No ⁶⁰Co was detected in the vegetation or water samples. The downward migration rate of ⁶⁰Co in the upper 15 cm of soil ranged from 0.50 to 0.73 cm/yr. About 98%, 0.020 ± 0.011 Bq/cm², of ⁶⁰Co remained in the upper 15 cm of soil, which compared favorably with the expected ⁶⁰Co activity based on historical records of 0.019 ± 0.010 Bq/cm².     

虹鳟鱼鳃及肝脏多种CYP1基因表达模式作为生物标志物监测海河水污染状况

以虹鳟鱼为受试生物,以鳃与肝脏多种CYP1基因为生物标志物,在天津境内开展了野外监测实验,分析多种CYP1转录物的表达量变化及它们在不同监测位点的表达模式.实验通过鱼类吊网在特定水域进行野外监测.结果表明,葛沽与海河入海口的6种CYP1基因表达模式很相近,但表达量不同,表明两地的污染成分相近似但水中污染物负荷不同.除了在马厂减河外,CYP1C1/C3在葛沽与入海口受到明显诱导作用,表明马厂减河中存在的污染物种类不同于其它监测位点.因此,利用虹鳟鱼鳃与肝脏中多种CYP1基因表达模式作为生物标志物监测污染物有着很好的前景,不仅可以作为研究环境污染物对水环境和鱼类健康影响的重要手段,还可以为进一步解释化学混合物成分与多种生物反应之间关系提供理论基础.     

Parallel and serial methods of calculating thermal insulation in European manikin standards

Standard No. EN 15831:2004 provides 2 methods of calculating insulation: parallel and serial. The parallel method is similar to the global one defined in Standard No. ISO 9920:2007. Standards No. EN 342:2004, EN 14058:2004 and EN 13537:2002 refer to the methods defined in Standard No. EN ISO 15831:2004 for testing cold protective clothing or equipment. However, it is necessary to consider several issues, e.g., referring to measuring human subjects, when using the serial method. With one zone, there is no serial-parallel issue as the results are the same, while more zones increase the difference in insulation value between the methods. If insulation is evenly distributed, differences between the serial and parallel method are relatively small and proportional. However, with more insulation layers overlapping in heavy cold protective ensembles, the serial method produces higher insulation values than the parallel one and human studies. Therefore, the parallel method is recommended for standard testing.