NUTRIENT CYCLING OF N AND P BY A MIXED FOREST OF CUNNINGHAMIA LANCEOLATA AND TSOONGIODENDRON ODORUM IN SUBTROPICAL CHINA

通过对福建三明 2 7年生杉木 (Cunninghamialanceolata) 观光木 (Tsoongiodendronodorum)混交林 (混交比例2 :1)及杉木纯林群落N、P养分循环进行为期 2年的研究。结果表明 ,混交林中杉木和观光木地上各组分的N、P含量大小均为叶 >活枝 (或皮 ) >枯枝 >干 ,而根系的则随径级的减小而增大 ,且观光木各组分的N含量均高于杉木的 ;混交林群落的N、P总积累量达 5 85 .2 2 3kg·hm-2 和 12 8.784kg·hm-2 ,分别是纯林群落的 1.5倍和 1.3倍。混交林群落N、P养分年归还量达 75 .740kg·hm-2 和 5 .493kg·hm-2 ,分别是杉木纯林的 113 .0 %和 79.6 %。混交林通过凋落物、降水淋溶和细根枯死 3种途径的N归还量分别占群落总归还量的 6 7.1%、8.4%和 2 4.5 % ,而纯林的则分别为 6 9.3 %、8.1%和 2 2 .6 % ;混交林 3种途径的P归还量分别占群落总归还量的 6 4.0 %、7.5 %和 2 8.5 % ;而纯林则为 74.8%、5 .3%和 19.9%。混交林中林下植被层的N、P归还量分别占群落总归还量的 14.8%和 37.3 % ;而纯林的则为 2 9.5 %和 5 9.4%。混交林群落的N、P富集率和利用系数均低于纯林的 ,而周转期则均大于纯林的。混交林群落的P吸收系数小于纯林的 ,而循环系数则高于纯林的 ,但其两者的N吸收系数和循环系数则相似。A study on the cycling of N and P in a pure forest of Chinese fir ( Cunninghamia lanceolata (Lamb.) Hook. and a Chinese fir_ Tsoongiodendron odorum Chun mixed forest (2 Chinese fir: 1 T. odorum ) over two years was carried out in Sanming, Fujian, China. For both Chinese fir and Tsoongiodendron odorum, the concentrations of N and P in aboveground fractions were in the order of leaves>living branches (or stem bark)>dead branches> stem wood, and those in roots increased with an increase in root diameter. N concentrations in various fractions of T. odorum were higher than their respective values for Chinese fir. The standing crops of N and P in the mixed stand were up to 585.223 kg·hm -2 and 128.784 kg·hm -2 , being 1.5 and 1.3 times as much as that in the pure stand, respectively. The annual return of N and P amounted to 75.740 and 5.493 kg·hm -2 in the mixed forest, respectively, being 113.0% and 79.6% of that in the pure forest. The fractions of annual N return through litterfall, rain leaching and fine root turnover were 67.1%, 8.4% and 24.5% in the mixed forest, respectively, and the corresponding values were 69.3%, 8.1% and 22.6% in the pure forest. These three pathways contributed to 64.0%, 7.5% and 28.5% of total P return in the mixed forest, and 74.8%, 5.3% and 19.9% in the pure forest, respectively. 14.8% of N return and 37.3% of P return in the mixed forest, and 29.5% of N return and 59.4% of P return in the pure forest were derived from the undergrowth vegetation. For both N and P elements, the enrichment ratios and the utilization coefficients were lower, and the recycling periods were higher in mixed forest than in pure stand. For P, the absorption coefficient was lower, and the cycling coefficient was higher, in mixed forest than in pure forest, while there were no significant differences for those of N between the two forests.中国博士后科研基金;; 福建省科委重大基础研究项目 ( 2 0 0 0_F_0 0 4);; 高等学校骨干教师资助计划项

SVD-LMD联合降噪和TEO的滚动轴承故障诊断

针对随机噪声背景下滚动轴承局部损伤信息提取困难的问题，提出了一种奇异值分解（Singular value decomposition，SVD）和局部均值分解（Local mean decomposition，LMD）联合降噪，并结合Teager能量算子（Teager energy operator，TEO）的特征提取新方法。首先，利用SVD方法对滚动轴承故障振动信号进行处理，初步剔除背景噪声；然后，使用LMD方法分解降噪后的信号，依据相关系数指标筛分出敏感乘积函数（Product function，PF）并加以重构；最后，对重构的信号进行TEO解调分析，将解调谱中幅值突出的频率成分与故障特征频率理论值进行对比，提取故障信息。结果表明，该方法可有效提取轴承局部损伤的特征频率，最终实现故障诊断

A case-control study of risk factors for low birth weight infants in Xiamen City

目的探讨厦门市低出生体质量儿的发生及其危险因素,为预防和降低低出生体质量儿的发生提供科学依据。方法采用1∶3配对病例-对照方法,在厦门市属医疗机构收集86例低出生体质量儿及按匹配条件收集258例对照,利用条件lOgISTIC逐步回归模型分析其影响因素。结果母亲文化程度在大专及以上、家庭月人均收入≥4 000元、孕前1年至孕13周内补充叶酸、饮食清淡和产检次数≥5次是保护因素,而妊娠期高血压疾病、孕期服用抗生素、孕周4 000 yuan,intake of folic acid a year before pregnancy to the first three months of pregnancy,balanced diet,and more than 5times of antenatal examinations.The risk factors of LBW infants included hypertensive disorder complicated with pregnancy,intake of antibiotics,gestational age less than 37 weeks,increase in amplitude of gestational BMI<5,father was worker or technician,and eating raw garlic more than 2times per week.Conclusion The above causes may contribute to low birth weight infants in Xiamen City and appropriate preventive measures should be taken to reduce the incidence.福建省科技厅自然科学基金面上项目(No.2012D046); 厦门市科技局科技计划项目(No.3502Z20124057); 湖里区科技局(No.12社09