Isolation and characterization of bacteria associated with a syndrome disease of sea urchin Strongylocentrotus intermedius in North China

Sea urchin, Strongylocentrotus intermedius, transplanted from Japan in 1989, has been widely cultured along the coasts of Liaoning and Shandong Provinces and has become the dominant and most economically important maricultured species in North China. However, a lesion syndrome symptom of S. intermedius broke out frequently these years, showing lethargy in activities, blackish peristomial membrane and body well lesions, and brought about high mortality eventually. Six representative prominent bacterial strains were isolated from diseased sea urchin from September 2009 to January 2010. By means of API 20NE and 16S rRNA gene sequences analysis, isolates were identified as Shewanella aquimarina, Pseudoalteromonas tetraodonis, Vibrio shilonii, V. harveyi, V. fortis and V. splendidus. Bacterial challenge tests showed that their representative isolates were virulent to S. intermedius with LD₅₀ values ranging from 9.2 × 10⁴ to 3.4 × 10⁶ CFU/g body weight, among which S. aquimarina , V. fortis and P. tetraodonis were highly virulent, and the other three isolates showed moderate virulence. The results indicated that a variety of bacteria including Shewanella, Pseudoalteromonas and Vibrio were involved in the mortality of S. intermedius, and the six isolates were opportunistic pathogens of sea urchins. All isolates reported herein were sensitive to ampicillin, enrofloxacin, ofloxacin, doxycycline and florfenicol.     

3WZ-700型自走式果园风送定向喷雾机

针对现代果园低矮密植的种植特点,设计了3WZ-700型自走式果园风送定向喷雾机。通过理论计算和虚拟样机技术,完成整机结构设计和各关键部件技术参数的确定。设计了适应于低矮密植果园的圆环双流道风送雾化装置,确定叶轮直径0.7 m、出风口宽度0.13 m。实现风机转速0～2 000 r/min的无级变速。田间试验结果表明,树膛内部枝叶正、反面雾滴附着率分别为61.22%、20.90%;树膛外部枝叶正、反面雾滴附着率分别为77.22%、37.17%;作业效率为1.02 hm2/h。     

精密车削二维微位移刀架研究

设计了一种微米级切削加工的微位移刀架,该刀架可满足数控车床精密加工的需要。该刀架以压电微位移致动器为动力源,以双平行四杆柔性铰链为弹性导轨,以最大输出位移为主要参数,设计了微位移刀架的结构,计算和选择了微位移刀架的结构参数。通过理论建模和有限元分析,对该铰链机构的系统刚度进行了计算,并对二维微位移刀架的输出位移进行实验测试。实验结果表明:理论计算结果、有限元仿真计算结果与实验测试数据吻合,验证了设计方法的可行性。     

温室3P3R机械臂系统动力学建模与分析

针对温室等设施农业环境,设计了一种具有3P3R机械臂结构的机器人,为了分析机械臂的操作性能并实现精确运动控制,对机械臂进行了运动学和动力学分析;采用Kane方法和旋量理论分析方法建立了机器人的操作臂运动学和动力学模型,利用该模型,针对原理样机的具体结构,在Mathematica环境下研究了机械臂的操作性能,得到在一定作业任务规划下,末端执行器的位姿变化规律,以及按照该规划轨迹运动时各关节的驱动力;结果表明,结合了Kane方法和旋量理论的动力学模型具有准确、简单、有效等特点,能够满足机械臂的运动学、动力学分析的要求。     

基于奇异摄动理论的综合温室控制系统设计

为了建立集环境因子、作物生长过程和上层指标的综合温室控制系统,分析了现有温室控制研究成果,基于控制周期原则将温室控制系统分为分钟级温室环境因子控制系统(快速时变系统)、天或旬级的作物生长周期控制系统(中速时变系统)、年级的温室上层指标控制系统(慢速时变系统)。通过多时间尺度分析发现3类控制系统具有多时标特性,借助奇异摄动理论,对温室控制系统进行了分层递阶设计,进而得出该理论下的总体温室控制系统模型与控制器求解过程。通过算例演绎该设计方法的步骤,进行了仿真研究,结果表明,基于奇异摄动理论的温室控制系统设计思路清晰、计算量小、易于工程实现。     

颗粒料质量流量测量误差动态估算方法

提出了一种利用冲量原理测量固体颗粒物料实时物料速度和质量流量的方法,同时给出了一种可动态估算速度和质量流量测量误差的方法.利用自行设计的实验装置,并采用大豆作为实验材料进行了测量误差估算的实验,实验结果表明:在所设计的实验条件下,估算的质量流量相对误差最大值为4.00％,平均相对误差为1.44％;估算的速度相对测量误差最大值为9.69％,平均相对误差为5.03％,动态测量精度和总质量计量精度之间有较好的相关性.     

摆线泵内转子磨料流均匀化抛光及试验研究

为了降低内转子的表面粗糙度,提出了一种利用磨料流对内转子表面实现均匀化加工的抛光方法.采用与内转子壁面等宽度的方法设置模芯,通过建立均匀化流道,改善壁面的剪切应力分布,使内转子各曲面间的壁面所受剪切应力趋向一致.依据磨料流的流变特性,建立幂律方程,分析磨料流加工过程的剪切率及剪切应力分布状况,并利用COMSOL Multiphysics软件的CFD模块模拟磨料介质在均匀化流道下的表面加工流速、剪切率和剪切应力的分布.结果表明:在无模芯时利用磨料流加工,内转子各表面的剪切速率差值较大;置入模芯后内转子曲面各部分所受的剪切应力比无模芯时明显得到改善,经20次加工循环后,各表面间的粗糙度最大差值由无模芯时的0.847 μm降至0.277 μm,且有效地提高了加工效率及表面质量.     

Bacterial Flora in Turbot Scophthalmus maximus Cultured in Deepwell Seawater of Liaodong Peninsula

The microbial flora in turbot (Scophthalmus maximus) cultured in deepwell seawater from Liaodong Peninsula, China was studied for the first time. The total amount of aerobic meso- and psychrophilic microflora from the culturing water, gills, and skin were 3.46–3.82, 3.19–4.28, and 1.70–1.95 log cfu/g, respectively. Out of 204 strains isolated from fresh turbot meat with skin, Gram-positive bacteria accounted for 19.2% of the total aerobic meso- and psychrophilic microflora, and 72.1% were Gram-negative bacteria. Phylogenetic analysis was performed using 16S rDNA sequences of microbial flora isolated from turbot. The predominant bacteria in fresh turbot were Micrococcus, Serratia liquefaciens, and Enterobacteriaceae. Meanwhile, the bacterial flora of refrigerated turbot fish were investigated, and the results indicated that Shewanella putrefaciens was the predominant spoilage bacteria.     

施入保水剂土壤吸水膨胀试验

以施入保水剂的土壤为研究对象,建立了施入保水剂土壤吸水后的空隙变化模型,并对不同含水率条件下土壤孔隙进行了测定,对模型进行了求参和验证,表明此模型具有较好的模拟效果,并以此为基础对施入保水剂条件下的土体吸水膨胀和孔隙度变化进行了分析,结果表明,保水剂施入量越高,膨胀量增加越大,孔隙度的增加也越大.     

组合型垂直轴风力机结合角度对起动性的影响

与Savonius风轮组合使用是改善直线翼垂直轴风力机起动性的重要方法,而二者的结合角度对组合型垂直轴风力机的起动性有很大影响.首先,设计了采用FX63-145和NACA0018翼型的直线翼垂直轴风力机和Savonius风轮,利用风洞试验测试并分析了各自的起动性.然后,分别将Savonius风轮的最佳起动区域与两种直线翼垂直风力机的最差起动区域和最佳起动区域进行组合,测试了在这4种不同组合方式下的组合型垂直轴风力机的起动性.结果表明:对于采用对称翼型的直线翼垂直轴风力机,将直线翼垂直轴风力机的最佳起动区域与Savonius风轮的最佳起动区域结合的方法可以更好地提高组合型垂直轴风力机的起动性.而对于采用非对称翼型的直线翼垂直轴风力机,两种组合方式各有优缺点.