基于2DVD的非旋转折射式喷头水滴直径分布规律

采用基于三维视频粒子测量原理的视频雨滴谱仪(Two-dimensional video disdrometer,2DVD)对喷灌机中常用的Nelson D3000型喷头在多个工作压力下水滴直径沿射程的分布进行了测量,分析了水滴直径沿射程的变化趋势及水滴速度、水滴角度与水滴直径之间的关系。结果表明:水滴直径与射程符合指数函数关系,在距离喷头相同测点处,水滴直径随工作压力的升高而减小,而射程末端的水滴直径随着压力的升高而增大;水滴速度随水滴直径增加而增大,两者呈对数关系;水滴落地时与地面夹角(简称水滴角度)随水滴直径增加呈减小趋势,水滴直径小于1.0 mm时,50、100、150和200 kPa工作压力下,与地面夹角为90°的水滴个数占总水滴数的比值分别为90.46%、84.46%、89.91%和89.15%,其余水滴与地面夹角在30°~89°之间,水滴直径在1.0~2.25 mm范围内,水滴角度随水滴直径的增加迅速减小,水滴直径大于2.25 mm时减小趋势变缓,4个工作压力下最大直径水滴落地时与地面夹角平均值为45°;工作压力对于水滴直径与速度、水滴直径与角度之间的关系影响较小。     

针茅草颗粒对乌珠穆沁羊采食和反刍行为的影响

【目的】研究不同处理针茅草颗粒对乌珠穆沁羊采食和反刍行为的影响,为针茅草颗粒生产原料适宜含水量、粘合剂添加量和颗粒直径等技术参数的确定提供理论依据。【方法】用不同条件(原料含水率为12%~14%,14%~16%和16%~18%;颗粒直径为3,6和8mm;粘合剂添加量为1%,3%和5%)制备的针茅草颗粒对乌珠穆沁羊进行饲喂试验,对其采食和反刍行为进行观测。【结果】舍饲条件下,饲喂针茅草颗粒羊的平均昼夜采食时间302.18min,昼夜总反刍时间平均为377.43min,昼夜反刍周期19.40个、昼夜每个反刍周期持续时间22.51min,每个反刍周期逆呕食团27.37个,昼夜反刍食团咀嚼总次数为20 672.64次,2个食团吞咽平均逆呕间隔时间5.13s,每个食团的咀嚼次数为54.57次,咀嚼时间为60.23s。【结论】针茅在粉碎粒度为6mm、颗粒直径为8mm、原料含水率为14%~16%、粘合剂添加量为3%条件下加工成草颗粒,乌珠穆沁羊最喜食。     

港、澳、珠三角旅游互动合作及机制的演化研究

港、澳、珠三角地缘相连、资源互补、文化同源、经济相融、旅游产品丰富,互补发展的优势明显。三地游客互流呈现出互为目的地和中转地的特征。基础推动力、市场驱动力、政府调控力是推动三地互动合作的主要动力因素,其中,基础推动力在三地旅游互动合作发展的整个过程中起到重要的基础作用。起步发展期,政府调控力发挥了重要作用,市场驱动力则相对弱;快速发展期,市场驱动力则成为主要驱动因素;深入发展时期,政府调控力又发挥了不可替代的作用。但三地的旅游互动合作仍存在诸多障碍,继续增强游客互流的便捷性、拓宽合作领域、深化合作内容及优化空间布局是三地旅游互动合作的关键。     

Fisheries of two tropical lagoons in Ghana, West Africa

Abstract  The fisheries of two coastal lagoons, Keta and Songor, were studied as part of Ghana Coastal Wetlands Management Project (GCWMP) aimed at sustainable exploitation of wetland resources. Fish samples were obtained with seine nets and cast net as well as from local fishermen. Water quality parameters (pH, dissolved oxygen, temperature and turbidity) were similar in the two lagoons, except for salinity, which was significantly different ( P  < 0.001). Despite their close geographical proximity, the two lagoons supported different fish assemblages with the blackchin tilapia, Sarotherodon melanotheron Rüppell, and the redchin tilapia, Tilapia guineensis (Bleeker), being the most important commercial fishes in both lagoons. The number of individuals for each species in Songor Lagoon were far more abundant, with densities several orders of magnitude higher than in Keta Lagoon. However, both species were significantly larger ( P  < 0.01) in the latter [15–121 and 25–157 mm standard length (SL)] than in the former lagoon (30–102 and 15–95 mm SL) for S. melanotheron and T. guineensis respectively. Over-fishing, use of small-size mesh nets, limited mixing of marine and fresh water were some of the factors limiting fish production in both lagoons.     

福建泉州湾环境质量评价

本文依据2000～2001年福建主要港湾水产养殖容量研究的调查资料，分析并评价了泉州湾的环境质量。结果表明：泉州湾DO、pH值、COD和活性磷酸盐基本符合二类海水水质标准，而无机氮严重超标。由于福建省第三大河流晋江携带大量工农业废水排入该海湾，造成水质无机氮和活性磷酸盐含量偏高，潜在富营养化因素，应加强污水排放的治理和海域环境保护。     

两种多糖对齐口裂腹鱼生长、血清抗氧化指标及组织镉积累量的影响

为研究0.40%硫酸软骨素(CS)和酸解氧化魔芋葡甘露聚糖(AOKGM)对齐口裂腹鱼生长、抗氧化及镉胁迫之后抗氧化性能和组织中(肝脏、肾脏和鳃)镉积累量的影响,实验选取450尾初始体质量为(98.00±8.54) g的齐口裂腹鱼分为3组(对照组、AOKGM组和CS组),进行为期8周的养殖实验,然后每个实验组选取120尾齐口裂腹鱼暴露在镉环境中,进行15 d的镉胁迫实验(镉浓度分别为0、0.10、0.25和1.00 mg/L),分别对2种多糖在齐口裂腹鱼生长及抗氧化性能方面进行相关研究,以及分析镉胁迫后2种多糖的抗氧化性能和组织中镉的积累量。结果显示,与对照组相比,2种多糖显著提高了齐口裂腹鱼的特定生长率、脾体指数和头肾指数;粗脂肪、灰分和粗蛋白质相对于对照组也有显著影响。CS和AOKGM均显著提高血清超氧化物歧化酶(SOD)活性、总蛋白(TP)和一氧化氮(NO)含量,降低葡萄糖(GLU)含量;CS能显著提高血清谷胱甘肽过氧化物酶(GSH-Px)活性和胆固醇(TC)含量,降低丙二醛(MDA)含量。结果显示,与镉浓度0 mg/L相比,MDA含量在镉浓度为1.00 mg/L时最高,SOD活性在镉浓度为1.00 mg/L时最低,GSH-Px活性在镉浓度为0.25和1.00 mg/L时显著降低,NO含量在镉浓度为0.25和1.00 mg/L时显著升高。镉胁迫实验中,与对照组相比,2种多糖组的SOD活性显著提高,MDA含量降低;NO含量在镉浓度0.10～1.00 mg/L胁迫时显著降低;CS显著提高镉浓度0.10、0.25 mg/L胁迫下的GSH-Px活性,AOKGM组GSH-Px活性在镉浓度为0.25、1.00 mg/L时显著高于对照组。与无镉组对比,齐口裂腹鱼肝脏、肾脏和鳃镉的积累量在各镉浓度下显著增加;而CS和AOKGM均能够降低机体组织镉含量。研究表明,在饲料中添加0.40%的2种多糖均能提高齐口裂腹鱼生长、抗氧化性能,降低镉胁迫下鱼体肝脏、肾脏和鳃中镉的积累量,缓解镉对齐口裂腹鱼造成的氧化损伤,为齐口裂腹鱼饲料的开发提供新的理论依据。     

Monitoring Indo-Pacific humpback dolphin occurrences in a highly urbanized estuary for informing conservation and management

1. The estuaries within the Pearl River Delta are sites for large-scale urban development and offshore construction. These projects have conservation stakeholders calling for more protection for the Indo-Pacific humpback dolphins whose habitat overlaps with current and proposed construction sites.
2. Efforts to improve impact assessments are hindered by the lack of baseline data and comprehensive understanding of how often the dolphins are present in areas near or within locations targeted for further development. The Modaomen Estuary within the Pearl River Delta is a good example of this, with little consideration for the dolphins as no data on their diurnal and seasonal occurrences within the estuary exist.
3. A passive acoustic monitoring system was deployed over a calendar year from October 2016 to September 2017 to monitor the presence of humpback dolphins in the Modaomen Estuary.
4. Results indicated that the estuary is an important area for humpback dolphins, with regular diel rhythms and seasonality in detection rates. For example, higher detections were seen during the wet season than during the dry season. However, there was no significant difference in detection rates between the flood and ebb tides, or between high and low tidal phases.
5. Since the Modaomen Estuary is targeted for further development in the near future, these data provide the rationale for resource management and consent processes to consider potential impacts on the dolphins, as well as to aid marine spatial planning and conservation measures.

     

Influence of dietary protein levels on growth performance, carcass composition and liver lipid classes of juvenile Spinibarbus hollandi (Oshima)

A feeding trial was conducted to investigate the influence of dietary protein levels on growth performance, carcass proximate composition and liver lipid classes of juvenile Spinibarbus hollandi (Oshima), a cyprinid fish. White fish meal was the primary protein source in the study. Eight experimental diets containing 13–55% crude protein were fed to three replicate groups of six fish weighing nearly 8.5 g each for 10 weeks. Both percentage weight gain and feed efficiency ratio increased significantly with increasing dietary protein levels up to 31%, but there was no further increase for protein levels from 31% to 55%. Application of broken‐line regression analysis to the percentage weight gain provided an estimate of 32.7±1.5% dietary protein for maximum growth. The protein efficiency ratio and productive lipid value were inversely correlated with dietary protein level. The hepatosomatic index and the viscerosomatic index were also inversely related to dietary protein level. The carcass protein of fish fed lower protein diets was significantly lower than that of the fish fed higher protein diets. Carcass lipid content decreased with increasing dietary protein levels, whereas moisture was inversely related to lipid content. Both liver glycogen and liver lipid contents decreased with increasing dietary protein levels. Triglyceride was the major component in the liver lipid, and the amount of triglyceride deposited in the liver also decreased with dietary protein levels. The results indicated that both carcass proximate composition and liver lipid class of juvenile Spinibarbus hollandi were affected by dietary treatments.     

用于驱赶农作物有害动物的智能声防系统设计

针对农业生产中动物有害行为导致农作物减产和农产品价值严重损失的实际问题,设计研发出一种驱赶农作物有害动物的智能声防系统。该系统以无线传感器网络作探测和通信平台,采用以ARM9微处理器和AT89C51SND1单片机为核心的嵌入式系统构建总控制器和执行器硬件平台,通过热释电传感器对有害动物在农田中的出没位置进行探测,依据“作物种类–周围环境–有害动物–天敌”逻辑关系模型对其种类作出判断,然后由执行器播放该种动物对应天敌的叫声,从而实现对多种农作物有害动物的智能声防。与现有的驱赶模式易被有害动物适应且效果不佳相比,该系统具有驱赶效果好、有效作用面积大、可扩展性强及装设灵活等优点,是一种无污染、具有智能特性的驱赶农作物有害动物的有效解决方案。     

抽气方式与充气压力对盒式气调包装气体置换性能的影响

基于不同条件的气体置换流场分析是实现气体置换工艺参数与结构优化的基础。针对盒式气调包装机的关键装置—气体置换装置的物理模型进行流场分析,采用RNG k-ξ湍流模型对进行气流流场数值模拟,建立盒式气调包装气体置换结构内部三维流场;比较等效面积下3种抽气方式对包装内部气体置换性能的影响,确定抽气孔的优化布置方式;分析不同压差工况下的气体置换速度,确定充气压力适宜的工作范围。结果表明,当压强相对于极限真空处于粗真空时（0.04～ 0.1 MPa）,3种抽气方式的气体置换效率差异不显著,随着压强的减小（小于0.04 MPa）,中间抽气方式优于两边抽气方式;同时,采用中间抽气,两边四孔充气方式时,充气压力大于0.5 MPa,有利于获得较高的气体置换精度与置换效率。