基于IL-HMMs预测模型的地下水埋深预测研究

以西北干旱典型县域磴口县为研究区,基于增量学习的改进隐马尔可夫预测模型(IL-HMMs),对区域地下水埋深进行了预测研究。为检验IL-HMMs模型预测效果,将模型预测结果与2013年长观井的实测数据进行了比较;同时为检验模型的优劣性,与未经增量学习的隐马尔可夫模型(HMMs)、加权马尔可夫链(WMCP)和BP神经网络(BP neural network,BPNN)预测模型的预测结果进行了比较。结果表明:与其他几种预测模型相比,IL-HMMs模型预测精度显著提高,误差更小,有较好的鲁棒性。并使用IL-HMMs模型对2018年地下水埋深进行了预测,预测结果表明,2018年地下水年平均埋深略有增加、局部区域地下水埋深增量加剧。基于IL-HMMs模型的地下水埋深预测具有很好稳定性的同时对新数据加入又有很好的鲁棒性,可为地下水埋深动态预测提供思路与方法补充,为区域地下水资源开发利用和保护提供重要依据。     

我国甘蔗中耕机械发展现状及趋势

随着农业产业结构调整和人工成本增加,发展机械化成为甘蔗生产节本增效的迫切需求。甘蔗中耕机械化作业能一次完成松土、除草、施肥和培土等工序,有效改善土壤状况,深层保肥保水,为甘蔗生长创造良好的条件。介绍了甘蔗中耕机械生产技术、发展历程、机型特点以及效益,指出存在的问题,提出应重点发展高地隙底盘配套技术、多功能肥膜药一体化轻便型耕作培土机以及驱动型中耕联合作业机械。      

荧光成像技术在植物病害检测的应用研究进展

植物病害阻碍植物正常生长,对蔬菜产品品质安全造成威胁,病害检测可以有效控制植物病害发展,是提高果蔬品质安全和可持续生产能力的一个重要途径。所有的绿色植物在受到紫外光或可见光激发时,都会发出可见光波段的荧光。基于植物荧光的成像技术,是利用计算机模拟人眼的视觉功能,在不破坏植株外观且不影响其生长的情况下,获取植物的荧光图像,并通过图像处理算法,对植物的健康状况做出判断。本文对荧光成像技术及其在植物病害检测中的研究进行了综述,介绍了荧光成像的原理,分别从叶绿素荧光和其他色素荧光两方面总结了国内外研究现状。与可见光成像、高光谱成像、多光谱成像以及热成像技术相比,该技术具有可获取植物内部信息、受温湿度影响小、不局限于晴天采集、价格合理等优点。     

改进暗管排水结构型式对排水性能的影响

提出一种占用耕地少、排水流量较常规暗排大且环境友好的改进暗排。基于室内土柱试验,分析改进暗排在地表积水、土体饱和条件下的排水除涝性能及其机理,提出地表积水土体饱和入渗条件下改进暗排排水流量的理论计算公式。结果表明,改进暗排可以有效提高暗管排水能力,试验条件下,反滤体宽度为2~6 cm的改进暗排在自由出流条件下的排水流量为常规暗排排水流量的2~3倍;积水层深度相同时,改进暗排排水性能随反滤体宽度的增加而增大,但增幅逐渐减小;土体介质和反滤体的渗透系数差别越大,改进暗排的排水作用越明显。理论方法计算结果与试验结果相吻合,证明提出的理论计算公式是合理可行的。     

In situ net N transformations in pine,fir, and oak stands of different ages on acid sandy soil, 3 years after liming

Summary The effect of liming on in-situ N transformations was studied in two stands of different ages of each of Scots pine (Pinus sylvestris L.), Douglas fir [Pseudotsuga menziesii (Mirb.) Franco], and common oak (Quercus robur L.). The stands were located on acid sandy soils in an area with high atmospheric N input. The organic matter of the upper 10-cm layer of the soil, including the forest floor, had a relatively high N content (C: N ratio <25) in all stands. Using a sequential core technique, N transformations were measured in both control plots and plots that had been limed 3 years previously with 3 t ha^-1 of dolomitic lime. Limed plots had a higher net NO _inf3 ^sup- production and a higher potential for NO _inf3 ^sup- leaching than the controls in all stands except that of the younger oak. Net N mineralization did not differ significantly between limed and control plots in oak stands and younger coniferous stands but was significantly lower in the limed plots of the older coniferous stands. It is concluded that long-term measurements of net N mineralization in limed forest soils are needed to evaluate the effect of liming with respect to the risk of groundwater pollution.     

Behavior of Brick Samples in Aggressive Environments

The weathering of different brick samples ina range of aggressive environments has been studied.Brick samples were prepared using two clay types (fromGranada, Spain), different additives, and a range offiring temperatures (850–1100 °C). The brickscompositional and textural characteristics wereevaluated using XRD, SEM, hydric tests and mercuryintrusion porosimetry (MIP). The samples weresubjected to accelerate aging, including wet-dry,freeze-thaw and salt crystallization cycles. The decayof the bricks in polluted atmospheres was simulated ina static chamber containing sulfur dioxide (SO₂)at 25 °C and 50% relative humidity. Samplesfired at 1000 °C proved to be the most durable,with better hydric behavior (fast drying and slowwater absorption) and fewer micropores. However, theywere not suitable for salt-rich environments (badperformance in the salt decay test). Samples fired at850 °C turned out to be more resistant to saltdecay, but they showed a poor hydric behavior (slowdrying and rapid water absorption) and littleresistance to freeze-thaw and wet-dry cycles. Samplesfired at 1100 °C had good hydric behavior, theyperformed well in the salt decay test, but they didnot perform as well as the samples fired at1000 °C in most accelerated aging tests. Gypsumformed on all the brick samples submitted to SO₂atmosphere regardless exposure time (e.g. gypsumappears following just 24 h of exposure),composition, or firing temperature. Samples withdeposited particulate matter collected from vehicleexhausts (diesel, as well as leaded and non-leadedgasoline motor cars) resulted in the fastest gypsumdevelopment and greater abundance. On the other hand,the blank samples, and the samples withpollution-derived dust collected from historicalbuildings showed little gypsum development. Theimplications of these results in historicalbrick-building preservation in a range of aggressiveenvironments, and in polluted atmospheres inparticular, are discussed.     

浓缩风能型风力发电机的整体模型风洞实验（第Ⅲ报）

低速风洞内进行的实验结果表明：当风速为５．５０ｍ／ｓ时，浓缩风能型风力发电机模型的输出功率为１００Ｗ，是直径相等的普通型风力发电机（风力机和发电机的总机械效率为０．３３２时）的输出功率的３．８倍；其输出功率相当于目前我国草原上使用的小型风力发电机输出功率的６倍；并且该机组的起动风速比相同叶轮普通型风力发电机模型的起动风速低     

不同雨强和坡度条件下紫色土养分流失规律研究

采用室内模拟降雨装置,研究了三峡库区紫色土在不同雨强和坡度条件下的养分流失规律。结果表明,紫色土坡面流失养分主要由径流和泥沙携带,其中径流养分含量与雨强和坡度无关,但与产流过程一致。泥沙中养分含量与雨强无关,但随坡度增加而降低;泥沙养分含量与产沙量过程无关,但其流失量与产沙量过程一致。泥沙中各养分含量略大于降雨前表土养分含量,远大于径流养分含量,但由于径流中以速效养分为主,故径流携带的养分流失量不容忽视。     

Recovery of pigments from Origanum majorana L. by extraction with supercritical carbon dioxide

Extraction of pigments (chlorophylls and carotenoids) from marjoram (Origanum majorana L.) with supercritical carbon dioxide was investigated. The aim of this study was to map the effects of extraction pressure and temperature on the yield of coloring materials by applying a 3(2) full factorial design with three repeated tests in the center of the design. For comparison, laboratory and pilot plant Soxhlet extractions were carried out using ethanol and n-hexane solvents. The compositions of pigments in marjoram extracts were determined by HPLC. Similar amounts of carotenoids, in addition to 40% of chlorophylls and their derivatives, were recovered from the supercritical fluid extraction, in comparison to the ethanol Soxhlet extraction.     

长期免耕水稻田土壤的生物特征研究

对经过 10年半旱式免耕定位试验的水稻土主要微生物类群数量和微生物生物量的变化进行对比研究 ,结果表明 :实行半旱式厢作及垄作免耕法能够迅速地提高土壤有机质、全氮、全磷和速效氮、磷的水平 ;微生物数量和微生物生物量变化一般存在季节性规律 :春季高 ,夏季至夏末降低 ;各处理土体上层和下层 (0～ 7.5 cm,7.5～15 cm)的基本肥力特征及微生物特征无明显区别 ;免耕处理土壤 ,其微生物的季节性变幅较小 ,垄上或厢上土壤微生物生物量甚至表现反季节性 ,整个生长季节内稳中有升 ,有利于土壤有机物质的转化和土壤肥力的发挥