Lake Ontario ice coverage: Past,present and future

Lake Ontario ice conditions are statistically linked to regional temperatures recorded in Toronto, during the most recent climate normal (1980/81–2009/10). A metric was developed to capture the net melting effect of average winter temperatures to characterize lake ice conditions, referred to as Net Melting-Degree Days (NMDD). This metric was able to account for 78% of lake ice interannual variability (R² = 0.783, P < 0.001). Based on NMDD parameters, current lake ice conditions were characterized in four ways: heavy, moderate, light and very light. Lake Ontario ice conditions were reconstructed to create a hindcast for the span of the instrumental temperature record (1840/41–1979/80). Based on a decadal analysis, heavy ice seasons decreased significantly (R² = 0.658, P < 0.001) from the 1840s to the 2000s, declining from an average of 6 heavy ice seasons per decade during the most distant climate normal (1840s to 1960s) to an average of only 1 heavy ice season per decade during the most recent climate normal (1980s to 2000s). Finally, lake ice conditions are projected to the end of the 21st century, using an optimal ensemble of Global Climate Model outputs for two different climate change scenarios (RCP4.5, RCP8.5). Heavy ice seasons no longer occur as early as the 2050s under both RCP4.5 and RCP8.5. Whereas, very light ice seasons go from being an extreme in the baseline period (10%), to the dominant characterization of Lake Ontario ice conditions by the 2080s, for both RCP4.5 (73%) and RCP8.5 (100%).     

1971—2010年中国干湿区降雨资源变化特征分析

降雨在农业生产领域、科学技术领域以及预报洪涝灾害、分析水资源等方面意义重大。利用全国1971—2010年743个气象站点的逐日降雨数据,基于干旱区、半干旱区、半湿润区和湿润区的干湿区划分,对年降雨量和年降雨日数按等级进行划分,运用线性倾向率、累积距平、M-K检验和滑动t检验等方法系统分析了4个干湿区内不同等级年降雨量和年降雨日数变化特征以及各区域年降雨量时间演变特征。结果表明:①过去40 a各干湿区年降雨日数分布存在差异,其中湿润区年降雨日数呈中部高、周边偏低分布趋势;②干旱区北部小雨的降雨贡献率和频率较高,半干旱区大到暴雨的降雨贡献率和频率低下;③在年代际变化中,1991—2000年湿润区年降雨量增加幅度最大,2001—2010年半湿润区年降雨量变化不明显;④各干湿分区的年降雨量近40 a突变趋势不一致,湿润区在2002年发生从多到少突变,而半干旱区未发生突变。研究成果对于预测旱涝灾害、分析水资源及治理生态环境等方面具有参考价值。     

基于馈线负荷骤降度的配电网故障研判方法

针对自动化水平低的配电线路故障停电后难以准确快速定位故障区段和停电范围的问题,提出了一种基于馈线负荷骤降度的配电网故障研判方法。该方法在馈线首端有功功率的骤降度大于一定阈值时启动,然后利用计量自动化系统中配变的历史负荷数据预测故障前馈线上各配变的有功功率,并计算馈线上各开关的负荷占比。通过比较馈线负荷骤降度与各开关负荷占比值,判断故障跳闸开关及停电范围。工程实例的分析结果表明,该方法能够准确定位故障跳闸开关,实时性好,为配电网提供了一种不依赖配电网自动化系统的新的故障研判手段。     

锦州市早期住宅的居住实态调查

锦州市20世纪70～90年代所建住宅,受当时各种条件限制,建造标准较低,远不能满足今天的使用要求。为了探求其使用现状及存在问题,通过对有代表性的锦州早期住宅进行问卷调查、入户访问、摄像、绘图等居住实态调查,获得了相应的统计及实测数据,并对数据进行了分析及总结。结果表明,锦州城市早期住宅存在建筑面积小、户型很少、功能错位等弊端。旨在为今后锦州市20世纪70～90年代住宅改造更新设计提供依据,并强调住宅改造设计和研究应注重可持续发展。     

Global sensitivity analysis of yield output from the water productivity model

This study includes a global sensitivity analysis of the water productivity model AquaCrop. The study rationale consisted in a comprehensive evaluation of the model and the formulation of guidelines for model simplification and efficient calibration. The global analysis comprehended a Morris screening followed by a variance-based Extended Fourier Amplitude Sensitivity Test (EFAST) under diverse environmental conditions for maize, winter wheat and rice. The analysis involved twenty-two different climate-crop-soil-meteorology combinations. The main objectives were to distinguish the model's influential and non-influential parameters, and to examine the yield output sensitivity. For the AquaCrop model, a number of non-influential parameters could be identified. Making these parameters fixed would be a step towards model simplification. Also, a list of influential parameters was identified. Despite the dependence of parameter ranking on environmental conditions, guiding principles for priority parameters were formulated for calibration in diverse conditions, valuable to model users. For this model that focuses on modelling yield response to water, parameters describing crop responses to water stress were not often among those showing highest sensitivity. Instead, particular root and soil parameters, relevant in the determination of water availability, were influential under various conditions and merit attention during calibration. The considerations made in this study about sensitivity analysis method (Morris vs. EFAST), prior parameter ranges, target functions and ranking variation according to environmental conditions can be extrapolated to other conditions and models, if done with the necessary precaution.     

东北-内蒙古地区基于MODIS单、双卫星积雪数据及常规积雪观测结合的积雪日数研究

结合Terra和Aqua卫星的积雪产品,获取2001~2008年东北-内蒙古地区逐年积雪日数分布,并利用此数据对比Terra卫星积雪数据获取的逐年积雪日数。结果表明随海拔的升高,双星与单颗卫星积雪日数差异呈现明显增加的趋势。整个东北-内蒙古地区双星积雪日数平均高出单颗卫星积雪日15 d,但与台站积雪日数对比发现,双星积雪日数平均仍然偏低27 d。这说明,利用Terra和Aqua双卫星积雪监测数据能明显改善山区云对遥感监测的影响,同时也可以减少降雪初期和消融期由于积雪消融较快带来的积雪漏测,但不足以消除云等因素的影响。考虑到获取的2001~2006年台站年积雪日数与MODIS年积雪日数与有良好的统计关系,利用两者建立的线性统计关系修正整个东北-内蒙古地区的MODIS积雪日数,能够很好地消除云等因素带来的MODIS双卫星积雪日数偏小的问题,修正后台站与双星积雪日数之间的绝对误差由原来的27 d减小到18 d。     

改良A2/O工艺在南方雨季的工艺运行控制

介绍了南方雨季时某城市污水处理厂采取的措施，即通过对改良A^2／O工艺进行适当的工艺调整，使污水处理厂在雨季进水有机物含量较低，而TP偏高、泥砂含量较多、DO也偏高的情况下保证处理效果，并降低污水厂工艺设备遭受严重磨损的风险。     

浅谈一般性多建筑物的防雷设计

本文就笔者对有关规范的理解 ,根据当地年平均雷暴日、建筑物等效面积、建筑物所处地理位置及特点 ,通过计算实例 ,分析了一般性多层建筑物的防雷设计     

关于工程造价控制中冬施费计收办法的探讨

针对冬季雨季施工费用，各省市均已逐步形成成文的指令性文件。山西省1995版定额中明确规定了冬雨季施工费费率：直接费基础上的1．28％（一类）、1．09％（二类）、0．82％（三类）、0．34％（四类）。通过实例分析，当工程中采取了冬施方案时，上述费率远远不够实际发生所产生的费用，而当施工单位以合理停工等方式避免了冬季施工时，则不发生该笔支出。鉴于此，冬雨季施工费用应该被视为一种措施成本，在费用定额中单独子以考虑，并由业主支付。     

Growth and egg production of layer pullets can be affected by the method of supplying energy and protein sources

BACKGROUND: The effects of different methods of offering energy (ES) and protein (PS) sources on growth and egg production of layer pullets were assessed. From 9 to 22 weeks of age, 320 layer chickens (Isa Brown) were allocated to four treatments: 1, control (balanced diet); 2, E60:P40 (ES and PS in balanced diet sequentially during 60 and 40% of daily photoperiod respectively); 3, E40:P60 (ES and PS in balanced diet sequentially during 40 and 60% of daily photoperiod respectively); 4, EPFC (free choice between ES and PS in separate troughs). RESULTS: Sequential or free choice feeding between ES and PS to point of lay decreased feed intake and delayed onset of egg production (P < 0.05). Control pullets had higher body weight at first egg than E60:P40 and E40:P60 birds (P < 0.05). Pullets in the E40:P60 group consumed less ES and more PS than those in other groups (P < 0.05). During the laying period, E40:P60 birds had higher egg production and egg mass than E60:P40 birds. EPFC pullets had lower feed efficiency than control and E40:P60 pullets. CONCLUSION: Offering PS during 60% of the photoperiod to point of lay may decrease feed intake without affecting egg production. Copyright © 2009 Society of Chemical Industry