Evolution of overland flow after a severe forest fire,Point Reyes,California

Forest fires on granitic soils often increase overland flow and erosion. Runoff generation was monitored on a small hillslope plot on Mt. Vision near Point Reyes Peninsula, California, after it had been burned by a wildfire on October 3, 1995. After the fire, the ground surface was covered with up to 2 cm of ash, which overlaid a 5–20 cm thick hydrophobic (water repellent) soil layer. We used nine recording tensiometers to monitor soil-water potentials during infiltration and runoff. Surface-runoff rates were determined by diverting the flow into a collection tank. The subsurface flow through the upper 6 cm of soil was collected and measured in a second tank. The surface runoff was diverted to a tank in order to record its rate. The initial intense rainfall infiltrated into the base of the ash-bed; here, the hydrophobicity limited deeper penetration and led to both subsurface and shallow saturation overland flow. The preferential flow paths through the ash layer contributed to deeper water penetration. As the ash was eroded and consolidated with successive rainstorms, the preferential flow paths clogged, the infiltration capacity reduced, thus preventing the storage of shallow permeable soil; therefore, the runoff generation changed to Hortonian overland flow. Correspondingly, the runoff ratio increased from approximately 0.2 during the early storms to 0.8 during intense rain bursts. These results suggest that runoff mechanisms evolve simultaneously with the eroding soil surface.     

户用风光互补发电系统设计与经济评价(简报)

湖区渔民远离电网,获得生活用电是提高渔民生活质量的重要方面,风光互补发电系统的应用是解决离网地区电力供应的一个新的选择。以金湖县宝应湖为例,根据当地风能和太阳能资源,对风光互补发电系统进行设计,在确定风力发电机瓦数为150 W情况下,给其匹配85 WP太阳电池组件能满足用户用电需求,对风光互补发电系统进行成本效益分析,表明该系统在此地区推广有其经济可行性。     

高羊茅抗逆无性系的选择和其子一代在上海的草坪特性鉴定

为了提高高羊茅(Festuca arundinacea Schreb)的综合抗性和草坪质量,开展了高羊茅选择育种。2006年3月至2009年11月,在人工接种褐斑病菌、夏季人工涝害胁迫、以及在上海与江苏阜宁两地夏季与冬季自然逆境条件胁迫下,从17个高羊茅品种(系)的单株圃和小区约51万株单株中,筛选到11个(TF01、TF02、…、TF11)越夏性强和8个(TF31、TF32、…、TF38)越冬性强的单株建立无性系。2009年11月至2011年5月,对17个优良无性系的子一代和19个引进的品种与自育的老品系等对照材料在上海田间条件下进行了草坪特性鉴定。试验结果表明子一代草坪草综合抗性较强,草坪质量较好的排名前2位的材料为从"Plantation"中选得的"TF06"和从"TripleA"商品组合中选得的"TF34"。"TF06"子一代的夏季草坪草死亡率低,次年仲春恢复生长后盖度达93%,具有中等生长速度和叶片质地,且叶色为特有的灰绿色;而"TF34"子一代草坪草越冬性和越夏性均强,恢复生长后的草坪草盖度为85%,具有较慢的生长速度、较细腻的叶片质地和深绿色的叶色。除了上述2个突出的无性系子一代外,"TF05"和"TF36"等的综合表现良好,排名前10。这4个表现突出的无性系可供大面积扩繁种子用以推广示范,也可用以配制高羊茅新组合。研究表明选择优良无性系和筛选优良子一代建坪的高羊茅育种方法是有效的。     

不同百里香茎浸提液对黄瓜种子发芽率的影响

用蒸馏水、10%乙醇溶液和10%丙酮溶液浸提百里香茎段,将浸提液进行不同比例的稀释,用稀释后的浸提液处理黄瓜种子,统计发芽率,结果表明3种浸提剂的浸提液处理下,水浸提液处理的发芽率最高,其次为乙醇浸提液,丙酮浸提液的发芽率最低;1∶5的百里香茎水浸提液对黄瓜种子的萌发具有促进作用,而1∶1、1∶10、1∶15的处理对黄瓜种子的萌发具有抑制作用;百里香茎丙酮浸提液对黄瓜种子的萌发具有抑制作用,且1∶10的处理抑制能力相对其他处理较弱;百里香茎乙醇浸提液对黄瓜种子的萌发具有抑制作用,且1∶1的处理抑制能力较其他处理弱。     

沼气利用模式现状及发展新方向

概述了我国现有沼气能源利用的几种典型模式及各自特点,包括庭院生态模式、生态农业模式、生活污水处理模式、农业废弃物处理模式和生活垃圾处理模式。针对如何高效利用沼气能源价值,阐述了沼气发展的几个新方向,指出应将传统沼气技术与沼气发电、燃料电池等新技术结合起来,促进我国沼气产业发展。     

家蚕秋用品种资源秋繁继代及种性稳定性研究

为节省家蚕品种资源保存成本 ,减缓世代演替进程 ,避免因饲养环境不当而造成基因漂失 ,研究了家蚕秋用品种资源不经春季饲养只作秋繁继代的可行性。以 4个中系品种和 4个日系品种为研究材料 ,以供试品种春制冷藏浸酸种为对照种做常规技术处理 ,以秋制越年种为试验种 ,经复式冷藏至次年 8月与对照种同时出库 ,常规饲养。经 7年连续 7个世代对虫蛹生命率、4龄结茧率、全茧量、茧层量、茧层率、健蛹率、制种率、产卵量、孵化率等指标进行调查 ,结果表明 :对照种和试验种无显著差异 ,家蚕秋用品种资源秋繁继代能够保持种性的稳定。     

基于微热管阵列的太阳能温差发电组件效率影响因素分析

为了提高太阳能中低温利用效率,该文将微热管应用于太阳能温差发电中,制成太阳能光热发电组件,并对组件光热转换效率、热电效率的影响因素进行分析。分析结果表明：集热器在受到外部环境、热损失的影响下,瞬时热效率优于国家规定的太阳能集热效率;在温差为30 ℃时,不同对数热电单元对转换效率几乎无影响;温差越大,热电对数对转换效率影响越大,127对热电单元,在温差为270 ℃时,提高到6.53%,转换效率要比1对热电单元要高出4.12%;相同数目温差发电片采用不同的串并联方式,对发电效率也有较大影响;负载电阻低于2 Ω,4片并联的输出功率最大;负载电阻为1 Ω时,4片并联的输出功率可达0.39 W;负载电阻介于2和15 Ω之间时,2片串联再并联的输出功率最大;负载电阻为5 Ω时,达到0.52 W;负载电阻大于15 Ω,4组件串联时其输出功率最大。     

基于EWT-KMPMR组合模型的光伏电站短期功率预测

为提高光伏电站短期功率预测的精度,提出一种基于经验小波变换(empirical wavelet transform,EWT))和核最小最大概率回归机(kernel mini max probability machine regression,KMPMR)的组合预测模型,对晴天、阴天和雨天3种天气类型下的光伏电站出力分别进行了预测分析。该文首先采用EWT将相似日光伏功率序列分解为具有特征差异的AM-FM分量,然后根据各AM-FM分量的变化特点建立相应的KMPMR预测模型分别进行预测并叠加得到最终预测结果。试验结果表明,相比SVM方法,该文方法在晴天、阴天和雨天可提高预测精度(MAE)分别为56.19%、54.15%和76.33%;相比EMD-KMPMR方法,在降低近一半左右计算规模的同时,可提高预测精度(MAE)分别为9.42%、38.74%和64.52%。以阿克苏地区光伏电站实际运行数据进行试验验证表明,该文方法在3种天气类型下均可取得较高的预测精度。     

换热设备螺旋和直细通道内扇形凹穴对流体流动和传热的影响

为探究结构表面(如凹穴)对换热设备螺旋和直细通道内流体流动和传热影响的差异,在这2种通道的两侧面加入扇形凹穴,并采用数值方法研究其在不同雷诺数下流动、传热、熵产以及综合性能的影响。结果表明:凹穴对螺旋细通道内流体的流动影响明显,摩阻系数最大提高23%,而对传热和综合性能几乎没有影响;低雷诺数时凹穴对直细通道内流体的流动、传热和综合性能的影响不明显,而高雷诺数时影响显著,摩阻系数和努塞尔数最大分别提高50%和45%,最大传热强化因子达1.27;凹穴可减少螺旋和直细通道内流体流动和传热过程的熵产,但在高雷诺数时才比较明显地减少,且对直细通道的影响大于螺旋细通道,熵产增大数的最小值分别为0.34和0.73。研究结果可为微细通道换热设备的性能改善提供参考。     

Combination of Piper guineense Essential Oil with Cowpea Varietal Resistance in Control of Cowpea Seed Beetle,Callosobruchus maculatus Fabricius (Coleoptera: Chrysomelidae: Bruchinae)

To reduce the risks associated with over-dependence on synthetic insecticides and ensure leguminous food security,an experiment was conducted to evaluate the potentials of integrating Piper guineense essential oil(Pg EO)with cowpea varietal resistance in the control of cowpea seed beetle,Callosobruchus maculatus Fabricius.Four cowpea varieties(Sokoto,Drum,Oloyin and Gwallam)were studied.Data collected included oviposition,progeny emergence,Reproductive Efficiency(RE)and Percentage Seed Damage(PSD).At first filial generation,numbers of eggs laid on Oloyin variety treated with 25μL Pg EO per 25 g cowpea seeds(2.15)were significantly(p0.05)lower than the values obtained in untreated cowpea(3.61)and hexane-treated seeds(3.07).C.maculatus RE on Oloyin(33.73)was significantly(p0.05)lower than values obtained on other varieties(47.34-54.67)for seeds without Pg EO;and were significantly greater than 0.00 observed on Oloyin seeds treated with 50μL PgE O.PSD on Oloyin(6.63%)was significantly(p0.05)lower than the values obtained on Sokoto(10.04%)and Drum(9.79%)for seeds without Pg EO,while there was no damage in Oloyin treated with 50μL Pg EO.Significantly(p0.05)lower F2 progeny emergence occurred on Oloyin(4.02)and Sokoto(4.71)compared with Drum(9.03)and Gwallam(6.07)from the untreated cowpea seeds.The results implied that application of PgE O to Oloyin gave better protection from infestation of C.maculatus than other varieties.Hence,combination of varietal resistance with PgE O for management of bruchid could be an effective mean of improving cowpea food security.