长沙地区低温粮仓双层通风屋顶最佳保温隔热层厚度分析

粮仓围护结构保温隔热性能对储粮安全和粮仓能耗有重要影响。粮仓屋顶面积大,是粮仓围护结构接受太阳辐射最强的部位,外界热量主要通过屋顶传入粮仓,因此屋顶是粮仓围护结构保温隔热设计的最重要部位。双层通风屋顶、高反射率的屋面隔热涂料和保温隔热材料等节能技术近年来在粮仓屋顶设计中得到迅速发展和应用。考虑屋顶不同外表面太阳辐射反射率和自然通风对双层通风屋顶传热的影响,该文给出并试验验证了多层屋顶非稳态传热模型和双层通风屋顶传热模型,利用经过验证的屋顶传热模型进行屋顶能耗计算,采用经济性模型和全生命周期理论对长沙地区低温粮仓普通屋顶和双层通风屋顶最佳保温隔热层厚度进行分析,并对采用最佳保温隔热层厚度时的生命周期总投资、净收益及回收周期进行计算和比较分析。研究结果表明:屋顶外表面太阳辐射反射率对长沙地区低温粮仓屋顶最佳保温隔热层厚度和经济性有较大影响,双层通风屋顶可以减小屋顶最佳保温隔热层厚度,长沙地区低温粮仓可采用双层通风屋顶和高反射率的屋面隔热涂料降低粮仓能耗,减少因能源消耗而引起的环境污染问题。长沙地区低温粮仓普通屋顶挤塑聚苯乙烯和膨胀聚苯乙烯最佳保温隔热层厚度为0.106~0.183 m,生命周期内最大净现值为417~633.38元/m2,投资回收年限为2.39~2.96 a。低温粮仓屋顶最佳保温隔热层厚度随屋顶外表面太阳辐射反射率的增大而减小,双层通风屋顶可以减少屋顶保温隔热层投资回收年限。该屋顶最佳保温隔热层厚度确定方法对于指导低温粮仓屋顶保温隔热设计具有一定指导意义。     

简易人工控温室的研究与设计

研究了简易人工控温室的设计、性能及使用效果。控温室为2.4m×2m×2.1m可容纳试验鸡32～64只,生长猪6～8头。室温可控变化范围高于室外气温3～25℃,温度分布不均匀系数K_t为0.023,室内光照强度可控范围5～30lx,换气模式合理,使用效果良好,投资少,是一种符合国情,适用于动物环境研究的控温设施。     

密闭遮光型甲鱼温室热环境模拟与试验

为了预测和评价密闭遮光型甲鱼温室的湿热环境,构建了甲鱼温室湿热环境的一维传热理论模型。采用欧拉数值计算方法求解甲鱼温室的传热方程组,编制了基于Matlab的计算机程序,根据屋顶材料的热传导系数、屋顶的红外辐射特性、温室的结构参数、温室热量输入与气象参数等条件,模拟甲鱼温室传热过程,该模型可以获得甲鱼温室任意时刻的屋顶内外表面温度、室内温湿度、养殖水体温度以及热流量等数据信息,可为甲鱼温室的湿热环境综合分析提供依据。通过建立相应试验方案对模型结果进行验证,实测结果表明,屋顶外表面、内表面模拟温度与实测温度平均误差为1.96和0.9℃,养殖水体与室内空气模拟温度与实测温度平均误差为0.32与1.3℃,室内相对湿度模拟与实测平均误差为3%。模型的理论计算值与试验测定值较为一致,表明甲鱼温室的一维传热理论模型具有较高的准确性。     

日光温室保温被卷放位置对温度环境的影响

温室保温被卷放位置影响着室内的太阳能得热及通过前屋面的散热,从而影响着温室温度。该研究以室外气象因子为模拟输入条件,分别模拟晴天、阴天不同保温被卷放位置对12 m跨度日光温室温度环境的影响。保温被卷放位置分别为保温被卷至前屋面一半与至顶2种方案。模拟结果显示：白天保温被卷至前屋面一半的室内空气温度高于保温被卷至屋顶的温度,而夜间2种方案室内空气温度差异不明显;晴天保温被卷至屋顶与卷至前屋面一半相比,可明显提高夜间墙体表面温度,但对后坡的夜间表面温度影响较小。该研究结果对温室生产中晴天、阴天保温被卷的合理放     

北京市猪舍节能改造的节能及保温效果

为了寻找北京市猪场节能的途径,对北京市既有供暖猪舍建筑围护结构保温性能进行了调查,并对370 mm厚墙、黏土瓦屋顶猪舍进行了墙体外贴保温板、黏土瓦屋顶上增加彩钢夹芯板保温层等节能改造,对节能潜力进行了估算,然后通过温度实测试验比较了节能改造舍与对照舍冬季的热环境状况。结果表明,北京市猪舍墙体、屋顶、窗户均不够节能;在假设供暖猪舍舍内冬季温度为20℃,供暖期为125 d的情况下,370 mm厚墙、黏土瓦屋顶猪舍1个采暖季的耗煤量为72 kg/m2,经过节能改造后,可节能69%。节能改造的投资回收期约为7.4 a。在舍外日平均温度为2.6~9.3℃情况下,试验节能改造舍舍内日平均温度较对照舍高1~3℃。舍外逐时温度越低,节能改造舍与对照舍内逐时温度差越大。试验期间,舍外逐时温度最低值为-2.3℃时,节能改造舍较对照舍逐时温度提高3.6℃。该文可为北京市既有供暖猪舍改造方案提供参考。     

日光温室三重结构相变蓄热墙体传热特性分析

针对目前国内日光温室墙体在热工性能设计方法方面存在的不足,该文提出了日光温室三重结构相变蓄热墙体构筑方法;结合试验结果,提出了关于该结构墙体传热性能分析方法及其评价指标。分析结果表明：1）三重结构墙体有着较好的蓄放热性能,利用墙体内侧（温室侧）的相变蓄热材料,可以显著提高墙体太阳能利用率,在太阳日累计辐照量为9.32 MJ/m2下,比参照温室北墙体的有效蓄热量提高了26.6%;夜间,相变温室三重结构墙体的累积供热量比参照温室砌块砖墙体的提高了16.2%,并且该墙体相变材料层的单位体积有效蓄热量为80.0 MJ/m3,是三重结构墙体中砌块砖层有效蓄热量的10倍;2）透过前坡屋面照射在温室北墙内表面太阳能影响墙体温度变化的深度有限,约占0.90 m厚三重结构墙体的33.3%,并且在温室墙体内部存在着温度稳定区,其厚度占0.90 m厚三重结构墙体的61.1%。试验结果表明仅通过增加温室墙体厚度以提高墙体的太阳能显热蓄热效率是非常有限的。该研究结果可为日光温室墙体的合理构筑、相变蓄热技术在日光温室的应用以及温室墙体的相变传热问题分析提供参考。     

规模化奶牛场粪污全量贮存及肥料化还田工艺设计

为推进粪污全量贮存和肥料化还田模式在规模化奶牛场的应用,该研究以存栏500头规模奶牛场为例,分析了粪污收集量、贮存工艺与设施和粪肥还田等内容,提出了粪污贮存池设计容积和粪肥还田配套土地面积等参数。结果表明：奶牛粪污全量收集量为17.33 t/d,全量贮存设施分为舍内贮存池和舍外贮存囊2种。单个舍内贮存池尺寸为85 m×12 m×2 m（长×宽×深）,粪污存储期9个月,所需贮存池数量为5个,总容积10 200 m3;舍外贮存囊占地尺寸为90 m×30 m（长×宽）,深2.2 m,总容积5 615 m3。粪肥全部还田所需土地面积与种植作物类型和种植制度相关,种植作物为小麦、玉米、小麦+玉米和水稻（1年2熟）时,需配套土地分别为248.4、400.6、122.8和127.0 hm2。粪肥还田成本为10.37万元/a,全部还田可节省化肥22.8万元/a,年可产生经济效益12.43万元。     

南方双层塑料大棚智能增温器的研制及试验

为了提高大棚农业生产中的冻害防御能力,该文研制了用于南方塑料大棚冻害防御的温室大棚智能增温器,并实际试验了该增温器的使用效果和使用成本。该增温器以酒精作为燃料,以置于温室大棚内关键位置的温度传感器作为启动和关闭的信号源,能够根据棚内实际温度变化进行精确加温。在试验棚（增温器加热,长度和跨度为8 m×40 m的双层塑料大棚）和对照棚（不加热,长度和跨度为8 m×40 m的双层塑料大棚）进行了连续12 d的对比试验。试验表明,在夜间试验棚的温度比对照棚高2～3℃,维持此状态6 h所需要耗费的成本仅为30元左右。该增温器具有操作方便、费用较低、增温快速、使用环保的特点,为设施农业生产提供了一个高效的冻害防御工具。     

组装式太阳能双效温室应用效果试验

为解决目前日光温室普遍存在的设备简陋、环境调控与抗寒防病能力差、土地利用率与劳动生产效率低的问题,建造了组装式太阳能双效温室并进行试验。该文分别选择内保温和外保温太阳能双效温室(温室内配置太阳能集热器、蓄热水池和热泵机组在内的太阳能热泵系统)测试其保温降湿性能和增产效果,主要测试指标为空气最低温度、日平均温度、光照度、空气相对湿度,种植作物的单株产量、单位面积产量。测试结果表明:内保温组装式太阳能双效温室室内最低气温都在9℃以上,与对照温室相比,1月份试验温室室内平均气温提高3.4℃,1月份室内平均最低气温提高4.0℃;外保温太阳能双效温室1月份室内平均最低气温为12.5℃,空气相对湿度控制在80%以下,比对照温室室内温度提高3.8℃,蔬菜增产19%~55%。组装式太阳能双效温室改善了温室的环境条件,提升了日光温室抗寒防病和增产增收的能力,该温室的研究与应用为中国北方同类地区提供借鉴与参考。     

沙柳沙障防风效益模拟试验研究

研究设定了2组试验,用沙柳柳条人工插成方格沙障,一组方格沙障高度1 m,规格分别为4 m×4 m,5 m×5m,6 m×6 m;另外一组方格沙障高度1.5 m,规格分别为6 m×6 m,7.5 m×7.5m,9 m×9 m。测定了每种规格沙障的地表粗糙度,防风效益。试验结果表明:在宽高比相同的情况下,1 m高的沙柳沙障的粗糙度大于1.5 m高的沙障,防风效益也好于1.5 m高的沙障;而在沙障高度一定的情况下,随着沙障面积的增大,沙障的防风效益在逐渐减弱。     

低氮和干旱胁迫对富士和秦冠生长及氮素利用的影响

【目的】以富士（Fuji）、 秦冠（Qinguan）嫁接在平邑甜茶（Malus hupehensis Rehd.）上的当年生盆栽苗为试验材料,采用砂培方法,研究了缺氮胁迫和干旱对富士和秦冠生长情况、 光合参数、 植株各部位氮磷钾含量及氮素利用效率的影响,分析比较了低氮干旱条件下富士和秦冠生长及氮素利用的差异,以期为果树生产高效肥水利用提供理论指导。【方法】试验共设四个处理: 正常氮正常水（ZZ）、 低氮正常水（DZ）、 正常氮干旱（ZG）、 低氮干旱（DG）。氮素和水分均设置两个水平,分别为正常氮（6 mmol/L NO-3-N）、 低氮（0.3 mmol/LNO-3-N）、 正常供水（保持盆中砂子相对含水量为饱和含水量的80%~85%）、 干旱处理（保持盆中砂子相对含水量为饱和含水量的60%~65%）。【结果】富士和秦冠的生物量（茎和叶）、 株高茎粗等生长指标以及光合速率、 气孔导度、 蒸腾速率均为正常氮正常水（ZZ）＞低氮正常水（DZ）＞正常氮干旱（ZG）＞低氮干旱（DG）,并且相对应处理下秦冠的以上指标均高于富士;正常供水下,缺氮处理使富士、 秦冠的根冠比比正常氮处理均有所增加,富士提高了2.05%,秦冠提高了22.40%。富士和秦冠的氮、 磷、 钾含量均表现出正常氮正常水（ZZ）＞低氮正常水（DZ）＞正常氮干旱（ZG）＞低氮干旱（DG）; 氮、 钾元素含量在植株各部位的分布顺序依次是叶＞根＞茎,磷元素则是根＞叶＞茎;光合氮素利用效率（PNUE）和氮素利用效率表现为秦冠处理之间差异极显著,富士处理之间差异不显著;秦冠的PNUE和NUE明显高于富士,在低氮正常水（DZ）处理下,秦冠氮肥利用率比富士高42.07%,在低氮干旱（DG）处理下高64.14%;低氮胁迫下富士和秦冠的NUE显著提高,并且秦冠提高的幅度高于富士。【结论】施用氮肥能够显著提高富士与秦冠的干物质量,同等水肥条件下,秦冠生长优于富士;水分亏缺会减少叶片对氮的吸收,干旱条件下适度增施氮肥,可提高果树的抗旱能力;低氮干旱胁迫下秦冠的生长指标、 光合指标及氮素利用效率指标均优于富士,表现出较强的抗低氮干旱胁迫的能力。     

Pasture Vegetation Elemental Analysis by Laser-Induced Breakdown Spectroscopy

Laser-induced breakdown spectroscopy (LIBS) is a new technique for the analysis of plant material. This study investigates the application of LIBS to pasture-based plant samples. The LIBS measurements were obtained from pelletized pasture samples (100 samples) that had been also analyzed by inductively coupled plasma–optical emission spectroscopy (ICP-OES) following microwave digestion for calibration and comparison purposes. Comparisons for elements sodium (Na), potassium (K), magnesium (Mg), calcium (Ca), manganese (Mn), iron (Fe), copper (Cu), zinc (Zn), boron (B), phosphorus (P), and sulfur (S) showed that LIBS could be used for almost all the standard profile total elements with concentrations down to low mg/kg levels (observed error of Na: 0.024 percent, K: 0.18 percent, Mg: 0.016 percent, Ca: 0.073 percent, P: 0.017 percent, Mn: 31 mg/kg, Fe: 150 mg/kg, Zn: 6.6 mg/kg, and B: 1.1 mg/kg). Elemental analysis at less than mg/kg levels was not possible using LIBS. The elements S and Cu were particularly difficult to analyze with reliability using LIBS at the concentration levels found in the plant samples. Replacing microwave digestion and subsequent ICP analysis with a direct analysis of dried plant samples using LIBS has the potential to improve the productivity and reduce the cost of testing.     

Faculty positions:Center for Agricultural Resources Research,Chinese Academy of Sciences

正The Center for Agricultural Resources Research(CARR),the Institute of Genetics and Developmental Biology(IGDB),Chinese Academy of Sciences,invites applicants for several research group leader positions.CARR is one of the research organizations in Chinese Academy of Sciences(CAS).We seek nominations and applications from individuals who have expertise and a record of accomplishment in research areas related to ecology,agro-hydrology,     

Biodiversity and ecogeography of wild Lactuca spp. in some European countries

Staff members of the Department of Botany of Palacký University in Olomouc and Gene Bank Department – Workplace Olomouc, Research Institute of Crop Production in Prague, Czech Republic, conducted an expedition in seven European countries (Austria, Czech Republic, France, Germany, Italy, the Netherlands, Switzerland) in August/September 1999 to collect wild Lactuca spp. germplasm and study its geographic distribution, ecology and biodiversity. During the mission, more than 600 locations were visited resulting in the collection of 602 seed samples (accessions) of wild Lactuca species and 13 seed samples of related genera (Chondrilla and Mycelis). Lactuca serriola f. serriola, L. serriola f. integrifolia, L. saligna and L. viminea subsp. chondrilliflora were prevalent in southern Europe (Italy, France), however, only L. serriola was common in central and western Europe (Austria, Czech Republic, Germany, Netherlands, Switzerland). The greatest diversity of Lactuca species was found in France, where also the most seed samples (165) were collected. The most characteristic habitats with a high density of Lactuca spp. populations were observed along roads and highways, grassy ditches, ruderal communities, and dust-heaps. Natural infections by powdery mildew (Erysiphe cichoracearum) and downy mildew (Bremia lactucae) on some wild Lactuca spp. were observed. Recent observations concerning the geographic distribution, population structure, habitats, and natural occurrence of diseases of Lactuca spp. are discussed. This assemblage of genetic resources of Lactuca spp. can serve as the basis of future studies of species diversification, spatial population structure, plant microevolution, domestication processes, and genetic variability of host-parasite interactions.     

Macroinvertebrates in North American tallgrass prairie soils: effects of fire, mowing, and fertilization on density and biomass

The responses of tallgrass prairie plant communities and ecosystem processes to fire and grazing are well characterized. However, responses of invertebrate consumer groups, and particularly soil-dwelling organisms, to these disturbances are not well known. At Konza Prairie Biological Station, we sampled soil macroinvertebrates in 1994 and 1999 as part of a long-term experiment designed to examine the effects and interactions of annual fire, mowing, and fertilization (N and P) on prairie soil communities and processes. For nearly all taxa, in both years, responses were characterized by significant treatment interactions, but some general patterns were evident. Introduced European earthworms (Aporrectodea spp. and Octolasion spp.) were most abundant in plots where fire was excluded, and the proportion of the total earthworm community consisting of introduced earthworms was greater in unburned, unmowed, and fertilized plots. Nymphs of two Cicada genera were collected (Cicadetta spp. and Tibicen spp.). Cicadetta nymphs were more abundant in burned plots, but mowing reduced their abundance. Tibicen nymphs were collected almost exclusively from unburned plots. Treatment effects on herbivorous beetle larvae (Scarabaeidae, Elateridae, and Curculionidae) were variable, but nutrient additions (N or P) usually resulted in greater densities, whereas mowing usually resulted in lower densities. Our results suggest that departures from historical disturbance regimes (i.e. frequent fire and grazing) may render soils more susceptible to increased numbers of European earthworms, and that interactions between fire, aboveground biomass removal, and vegetation responses affect the structure and composition of invertebrate communities in tallgrass prairie soils.     

Properties of anaerobically digested and composted municipal solid waste assessed by linking soil mesofauna dynamics and nitrogen modelling

We have studied the effect of anaerobically digested (ADMSW) and composted municipal solid waste (CMSW) on mineralization and foodweb dynamics to verify the hypothesis that ADMSW would immobilize N right after addition to soil in contrast to addition with CMSW. Another hypothesis was that the mesofauna (enchytraeids and microarthropods) would stimulate N release from the decomposer community. We measured excretion of -N and urea-N from the mesofauna and hypothesized that enchytraeids would release urea. ADMSW and CMSW were amended to pots with sandy loam and barley. The pots were divided into treatments with or without mesofauna. Mesofauna, plant N and biomass, soil N and ergosterol (fungal biomass) were measured over a 113-day period of four equidistant samplings. Soil respiration, N mineralization and N release by the mesofauna were modelled from concurrent studies. ADMSW- and CMSW-treated soils initially (<20 days) immobilized N. The amendments did not increase plant growth substantially, and this was probably due to N-limitation in the early stages of plant growth. Enchytraeid abundance was about three times higher in ADMSW- than CMSW-treated soils, indicating that ADMSW contained more labile compounds, bacteria, and microfauna. The mesofauna did not affect N-content, but the cumulated -N excreted by the mesofauna was estimated to be substantial and about one-fifth of total plant N in ADMSW. An explanation for this discrepancy might be that in the absence of the mesofauna, other members of the detrivore and microbivore community performed the mesofauna’s function. Neither enchytraeids nor microarthropods excreted urea.     

Faculty positions: Center for Agricultural Resources Research,Chinese Academy of Sciences

正The Center for Agricultural Resources Research(CARR),the Institute of Genetics and Developmental Biology(IGDB),Chinese Academy of Sciences,invites applicants for several research group leader positions.CARR is one of the research organizations in Chinese Academy of Sciences(CAS).We seek nominations and applications from individuals who have expertise and a record of accomplishment in research areas related to ecology,agro-hydrology,     

Faculty positions: Center for Agricultural Resources Research,Chinese Academy of Sciences

正The Center for Agricultural Resources Research(CARR),the Institute of Genetics and Developmental Biology(IGDB),Chinese Academy of Sciences,invites applicants for several research group leader positions.CARR is one of the research organizations in Chinese Academy of Sciences(CAS).We seek nominations and applications from individuals who have expertise and a record of accomplishment in research areas related to ecology,agro-hydrology,     

Variation in quality parameters between and within 14 Nordic tree fruit and berry species

Abstract

A 3-year study was carried out to investigate quality parameters in 14 tree fruit and berry species grown in southern Norway. The species were blueberry, apple, aronia, sour cherry, sweet cherry, red raspberry, strawberry, blackcurrant, gooseberry, red currant and elderberry, harvested along with wild bilberry, cloudberry and lingonberry. Significant differences between species were identified for all quality parameters. The coefficient of variation between species was lowest for pH (12.5%), dry matter (18.9%) and soluble solids (25.3%), followed by titratable acids (59.3%), total phenolics (83.8%), antioxidant capacity FRAP (85.7%) and antiradical power by the DPPH-assay (97.8%), total monomeric anthocyanins (132%) and ascorbic acid (137%). Average coefficient of variation within species were lower and ranged from 4 (pH) to 62% (ascorbic acid). Only the FRAP values were significantly affected by harvesting year with lower levels in 2004 than in 2005 and 2006. There were significant interactions between species and harvesting year for dry matter, soluble solids, pH, ascorbic acid and FRAP. The results indicate generic ranges in composition within species independent upon growing location and climate, and the composition of the tree fruits and berries is not likely to deviate from these ranges. It is concluded that desirable composition of tree fruits and berries and their products should primarily be achieved by selection among species rather than searching fors broadened variation within individual species.     

Potassium Fixation and Release Characteristics in Rhizosphere and Nonrhizosphere Soils for a Rapeseed–Rice Cropping Sequence

Potassium (K) fixation and release in soil are important factors in the long-term sustainability of a cropping system. Changes in K concentration and characteristics of K fixation and release in rhizosphere and nonrhizosphere soils in the rapeseed (Brassica napus L.)–rice (Oryza sativa L.) rotation were investigated using a rhizobox system. The concentrations of different forms of K in both rhizosphere and nonrhizosphere soils decreased with plants compared to without plants, regardless of K fertilizer application. Potassium uptake by crops mainly came from the rhizosphere soil. In the treatment without K fertilizer (–K), the main form of K supplied by the soil to the crops was 1.0 mol L^?1 nitric acid (HNO₃) nonextractable K, followed by nonexchangeable K, and then exchangeable K. In the treatment with K fertilizer (+K), the main K forms supplied by the soil to the crops were exchangeable K and nonexchangeable K. The amount and rate of K fixation after one cycle of the rapeseed–rice rotation was greater in rhizosphere soil than in nonrhizosphere soil. The amount and rate of K fixation of soil in the +K treatment were significantly less than in the –K treatment. The cumulative amounts of K released with 1.0 mol L^?1 ammonium acetate (NH₄OAc) and 1.0 mol L^?1 HNO₃ extraction increased with the increasing numbers of extractions, but the K-releasing power of soil by successive extraction decreased gradually and finally became almost constant. The release of K was less in rhizosphere soil than in nonrhizosphere soil. The release of K in the +K treatment was similar to that in the –K treatment in rhizosphere soil, but the K release in nonrhizosphere soil was greater with the +K than the –K treatment. Overall, the information obtained in this study will be helpful in formulating more precise K fertilizer recommendations for certain soils.