长江中游西部地区洪水灾害的历史演变——人文因素与当前趋势

探讨了近3000年来长江中游西部洪水灾害发展的人文因素。古代（3000—700aBP）人口较少,多择地势高的岗地居住,只有少数沿江城市需要堤防保护;长江干流洪水可多处分道散流,所携带泥沙导致云梦泽解体消亡。自宋代开始,低地筑垸围湖,与水争地,但九穴十三口畅通,洪水灾害不严重。明代（700—450a B P）几乎完全堵塞了荆江北流的穴口,荆北大堤联成一体,但堤防薄弱,出现过30次决口成灾。清代以来,随着人口激增,与水争地矛盾加剧,堤防加高培厚,使荆江河道洪水位大幅度上升,溃堤和溃坝洪水灾害较明代成倍出现。同时,历代的“舍南保北”政策迫使长江干流大洪水中过半水量与泥沙向南泄入洞庭湖,曾使洞庭湖面积扩至6000km^2,以后洞庭湖迅速淤积萎缩。1949至1985年间,人口又一次迅速增长,进一步加强围湖垦殖,大量通江湖泊面积萎缩。除1954和1998年那样人所共知的严重洪水灾害外,内涝渍水灾害也非常严重,人类与洪水的矛盾达到了顶点。改革开放后,尤其是三峡大坝的修建,极大地改变了长江中游的水文情势,工业化与城市化的迅猛发展,农村人口压力减轻,而21世纪初期降水相对较少,因此当前相当一段时间长江中游洪水灾害大为缓和。应抓住时机,总结经验,在人地和谐的现代水科学技术理念指导下,制定21世纪前半期,特别是2020年前的长江水利和水资源发展规划,促使人与洪水和谐共处。     

辽东湾入海污染物调查及海域水质安全分析

对辽东湾入海污染源、污染物总量及近海海域水质调查、监测,并对其水质安全进行了分析、评估。其污染物主要来自沿海各城市排入近海的工业污水、生活污水、入海河流携带污染物,海水养殖过程中产生的废水、残留饵料、排泄物等以及沿海港口码头的作业船舶和海上航行作业的机动船等泄漏、倾废;氮、磷营养盐过度排放导致赤潮频繁发生,危及海洋生物的生存;水质有机污染严重致使海产养殖病害,生物物种减少;重金属、人工合成的难降解的有机物等有害有毒的污染物沉积近岸海底,对近海水质安全形成威胁。     

浅谈600 MW机组湿法脱硫吸收塔的设计

结合广东某600 MW机组吸收塔的设计实例,对吸收塔的结构尺寸、内部件及防腐等关键工艺设计进行了阐述,以便为国内同类型脱硫工程吸收塔的设计提供借鉴及参考.     

基于Gompertz的气象水文装备维修器材消耗量分析与预测

利用由Gompertz曲线推导出的生命周期曲线建立了气象水文装备维修器材消耗-时间模型.计算表明,由Gompertz曲线推导出的生命周期曲线可以较好地反映气象水文装备维修器材消耗量与时间之间的关系,所建模型的预测结果也较好,具有较高的实用性,为探索气象水文装备维修器材消耗规律提供了一种简单有效的科学方法.     

胶东地块在古生代的浮沉

胶东—京畿地块在古生代并非“铁板一块”。中泥盆一早石炭世,裂解再生临津江—烟南冒地槽带;中、晚石炭世,郯庐海湾仲入成“诸城海湾”,并可能有二叠纪沼泽盆地。中生代运动使胶东地块复杂化。     

Effect of elevated tropospheric ozone on methane and nitrous oxide emission from rice soil in north India

Physiological changes in crop plants in response to the elevated tropospheric ozone (O₃) may alter N and C cycles in soil. This may also affect the atmosphere-biosphere exchange of radiatively important greenhouse gases (GHGs), e.g. methane (CH₄) and nitrous oxide (N₂O) from soil. A study was carried out during July to November of 2007 and 2008 in the experimental farm of Indian Agricultural Research Institute, New Delhi to assess the effects of elevated tropospheric ozone on methane and nitrous oxide emissions from rice (Oryza sativa L.) soil. Rice crop was grown in open top chambers (OTC) under elevated ozone (EO), non-filtered air (NF), charcoal filtered air (CF) and ambient air (AA). Seasonal mean concentrations of O₃ were 4.3 ± 0.9, 26.2 ± 1.9, 59.1 ± 4.2 and 27.5 ± 2.3 ppb during year 2007 and 5.9 ± 1.1, 37.2 ± 2.5, 69.7 ± 3.9 and 39.2 ± 1.8 ppb during year 2008 for treatments CF, NF, EO and AA, respectively. Cumulative seasonal CH₄ emission reduced by 29.7% and 40.4% under the elevated ozone (EO) compared to the non-filtered air (NF), whereas the emission increased by 21.5% and 16.7% in the charcoal filtered air (CF) in 2007 and 2008, respectively. Cumulative seasonal emission of N₂O ranged from 47.8 mg m⁻² in elevated ozone to 54.6 mg m⁻² in charcoal filtered air in 2007 and from 46.4 to 62.1 mg m⁻² in 2008. Elevated ozone reduced grain yield by 11.3% and 12.4% in 2007 and 2008, respectively. Global warming potential (GWP) per unit of rice yield was the least under elevated ozone levels. Dissolved organic C content of soil was lowest under the elevated ozone treatment. Decrease in availability of substrate i.e., dissolved organic C under elevated ozone resulted in a decline in GHG emissions. Filtration of ozone from ambient air increased grain yield and growth parameters of rice and emission of GHGs.     

响应突发事件的大型装备应急备件调度模型研究

研究大型装备备件供应网络面临大规模突发事件时的应急备件调度问题。首先采用信息熵理论对应急维修点进行优先度权重排序;其次建立应急响应时间和需求满意度函数,并将量化后的时间满意度和需求满意度以作为模型的目标函数,构建了网络供应状态下应对突发事件的备件调度规划模型;最后以某大型装备企业备件的应急备件调度为例,验证了模型的有效性,给出调度优化方案。     

Incidence of thyroid disease following exposure to polybrominated biphenyls and polychlorinated biphenyls, Michigan, 1974-2006

Thyroid hormones, which influence body metabolism and development, could be affected by persistent organic pollutants. We sought to examine the relationship between polybrominated biphenyls (PBBs) and polychlorinated biphenyls (PCBs) and thyroid disease. We employed incidence density sampling to perform a nested case control analysis of the Michigan Long-Term PBB Cohort. Cohort members (n = 3333) were exposed to PBBs through contaminated cattle feed in 1973-1974 and to PCBs through daily life. Those with detectable serum PBB and PCB concentrations at enrollment were categorized into tertiles of PBB and PCB exposure. Case-patients were cohort members answering “Yes” to “Has a healthcare provider ever told you that you had a thyroid problem?” during follow-up interviews; control-patients were cohort members answering “No”. We used odds ratios (OR) with 95% confidence intervals (CI) to compare odds of thyroid disease by PBB and PCB exposure and by various risk factors. Total cumulative thyroid disease incidence after 33 years was 13.9% among women and 2.6% among men. After adjusting for body mass index, we found no statistically significant differences in odds of any type of thyroid disease among women or men with elevated PBB or PCB exposure. Compared to control-patients, women with thyroid disease had increased odds of being overweight/obese (OR = 2.82, 95% CI: 1.94-4.11) and developing infertility (OR = 1.71, 95% CI: 1.08-2.69), diabetes (OR = 1.61, 95% CI: 1.04-2.51), or arthritis (OR = 1.71, 95% CI: 1.18-2.50) during follow-up. Additional research should explore potential associations between PBBs/PCBs and thyroid disease among children exposed in utero.     

宜宾树叶开发利用及其前景

宜宾植被为亚热带常绿阔叶林,植物资源十分丰富,目前对树叶开发利用主要是茶叶、挥发油、蚕桑、中药材等。本文论述了宜宾植物资源开发的种类、经济效益及其前景。     

板料冲压成形中坯料优化设计方法研究

较为系统地介绍了冲压件坯料的优化设计方法 ,并比较分析了其各自的优缺点。相比于其他方法 ,一步模拟方法效率高、适应面广、功能较强 ,可以在产品的设计之初提供较为丰富的信息。因此 ,对其作了较为详细的论述。实例证明 ,一步模拟法可用于板料成形工艺方案的快速评价及参数优化。