4LL–1.5Y型联合收割机割台的振动特性

运用有限元软件ANSYS workbench仿真分析4LL–1.5Y型联合收割机割台,得到割台机架前6阶模态频率和模态振型,结果表明,割台在受振动时易产生变形的部位是割台机架的两侧壁和割台机架进口处的底板。利用三轴加速度传感和Co Co–80动态信号测试分析系统,分别测得割台机架关键部位的加速度信号,对比非田间作业试验发动机空转、整机运转(不行走)分别在怠速(700 r/min)、中速(1 200 r/min)、高速(1 800 r/min)和田间作业不同工况下各方向的加速度,各测点水平方向加速度是其他2方向的2~4倍,表明割台的振动主要以水平方向振动为主,其中倾斜输送器受振动比较严重,加速度最大值高达97.28 m/s2。对比有限元分析与振动试验结果发现,对割台振动影响较大的激励频率(20、22 Hz)几乎都出现在割台机架的模态频率(18.679 Hz)附近。     

不同光谱杀虫灯对苹果园害虫诱杀效果及灯下昆虫种群结构分析

为探明不同光谱杀虫灯对苹果园害虫的诱杀效果,评估不同光谱杀虫灯对果园昆虫种群的影响。利用3种不同光谱杀虫灯于2015年7—8月在天水地区进行了苹果园害虫诱杀试验。结果表明,多光谱及LED多光谱杀虫灯的杀虫数量及杀虫谱优于频振式杀虫灯;频振式、多光谱、LED多光谱杀虫灯诱杀昆虫修正益害比分别为1:16.39、1:28.57、1:21.80;LED多光谱杀虫灯对鞘翅目、同翅目、半翅目及双翅目害虫诱杀效果优于其他杀虫灯;群落多样性参数分析显示,3种杀虫灯诱杀昆虫的Shannon-Wiener多样性指数(H′)分别为3.9231、3.6982、3.8134,均匀度(J)为0.7082、0.6399、0.6770。频振式、多光谱、LED多光谱杀虫灯对苹果园害虫均具有较好的防治效果,对天敌及中性昆虫均有一定的诱杀效果,本研究为太阳能杀虫灯科学使用提供了参考依据。     

基于微观特性分析风积沙粉体掺入提高混凝土的抗冻性

为研究冻融-盐浸环境下风积沙粉体混凝土的微观特性,设计了强度等级为C35、C25的风积沙粉体混凝土,在浓度为0%、3%、6%硫酸镁溶液中采用快冻法进行抗冻性试验,同时借助核磁共振技术、场发射扫描电镜及能谱分析研究其孔隙特征、微观形貌及水化产物。结果表明,风积沙粉体的掺入显著提高混凝土的抗冻性,且适当提高强度等级,有利于提高风积沙粉体混凝土抗冻性,其中强度等级为C35的风积沙粉体混凝土在6%MgSO_4溶液中可承受高达425次冻融循环;相对于基准组,风积沙粉体混凝土中有发育状况良好的针柱状产物钙矾石、纤维状产物石膏生成,填充因冻胀应力作用产生的裂隙,使其内部有害及多害孔数量低于普通混凝土29.78%,抗冻性增强。     

Efficiency of fisheries is increasing at the ecosystem level

Managing fisheries presents trade‐offs between objectives, for example yields, profits, minimizing ecosystem impact, that have to be weighed against one another. These trade‐offs are compounded by interacting species and fisheries at the ecosystem level. Weighing objectives becomes increasingly challenging when managers have to consider opposing objectives from different stakeholders. An alternative to weighing incomparable and conflicting objectives is to focus on win–wins until Pareto efficiency is achieved: a state from which it is impossible to improve with respect to any objective without regressing at least one other. We investigate the ecosystem‐level efficiency of fisheries in five large marine ecosystems (LMEs) with respect to yield and an aggregate measure of ecosystem impact using a novel calibration of size‐based ecosystem models. We estimate that fishing patterns in three LMEs (North Sea, Barents Sea and Benguela Current) are nearly efficient with respect to long‐term yield and ecosystem impact and that efficiency has improved over the last 30 years. In two LMEs (Baltic Sea and North East US Continental Shelf), fishing is inefficient and win–wins remain available. We additionally examine the efficiency of North Sea and Baltic Sea fisheries with respect to economic rent and ecosystem impact, finding both to be inefficient but steadily improving. Our results suggest the following: (i) a broad and encouraging trend towards ecosystem‐level efficiency of fisheries; (ii) that ecosystem‐scale win–wins, especially with respect to conservation and profits, may still be common; and (iii) single‐species assessment approaches may overestimate the availability of win–wins by failing to account for trade‐offs across interacting species.     

水稻抗性基因Pi对福建省稻瘟病菌优势菌群的抗性分析

【目的】抗病品种的合理利用和布局是实现水稻抗瘟持久化的关键因子之一。为明确水稻24个抗性基因在福建省的抗病性及其应用前景,【方法】首先分别采用全国稻瘟病菌生理小种鉴别品种和CO39近等基因系来鉴定2012-2015年间从福建省各稻区种植的普感品种丽江新团黑谷上采集的347株稻瘟病菌单孢菌株的生理小种类型和致病型,再测定24个抗性基因对福建省稻瘟病菌的抗性。【结果】根据全国稻瘟病菌生理小种鉴别品种对菌株的抗感反应,可将供试稻瘟病菌的生理小种划分为6个群36个生理小种,其中ZA、ZB和ZC为主要种群,ZC15、ZD7和ZB15为优势生理小种。根据CO39近等基因系的接种结果,将供试稻瘟病菌划分为17个致病类型,其中I34.1为优势致病型。供试的24个抗性基因对347株福建省稻瘟病菌菌株的抗性频率不同,抗谱为9.80%~89.91%。其中,Pi-k~m、Pi-7(t)、Pi-9(t)、Pi-k~p、Pi-k、Pi-k~h、Pi-z~5和Pi-ta(1)等8个抗性基因的抗病性较强,抗谱均高于70.00%。【结论】说明这8个抗性基因在福建省具有较好的应用前景,育种时可以考虑联合利用这些抗性基因。同时,实验结果表明,这8个抗性基因对主要生理小种的抗谱和主要致病型的抗谱均值高于69.00%,与其对所有测试菌株的抗谱吻合。说明利用稻瘟病菌的优势种群或优势致病型来鉴定水稻品种的抗病性是可靠的。     

基于遥感光谱的干旱区土地退化评价体系构建

干旱区土地退化(荒漠化)作为全球面临生态环境挑战之一,对粮食安全、环境质量和区域自然资源管理至关重要。土地退化本质是人与自然因素协同作用下土地利用/覆被类型、数量、结构以及功能的改变而引起的生态服务价值降低,核心是土壤和植被的退化。一方面,人与自然共同作用下的土地利用覆被可以表征土地退化状态,另一方面植被-土壤生境时间序列相互作用过程进一步辅助土地退化过程诊断。因此,该文首先从覆被结构、退化类型和退化程度3个层次建立干旱区土地退化状态评价体系。其次,采用GF-1/WFV时间序列遥感影像,基于多端元光谱混合分解模型建立土地利用/覆被精细分类量化表征下垫面质量属性,并进一步利用植被-生境组分互动特征参数进行功能量化,综合评价民勤2015年退化类型和退化程度。最后,结合地面立地景观照片以及采样点实测数据,对土地退化状态评价结果进行绝对定标和交叉验证。结果表明:遥感评价识别土地退化类型和程度的能力分别为87.5%和78.7%。对于民勤旱地系统,沙化过程、沙-盐化过程是主要的土地退化过程,轻度沙化、中度沙化为主导退化程度。该方法为宽波段遥感国产高分1号卫星在旱地系统土地退化状态信息提取和深入应用提供科学依据和实证研究。     

不同激励下宽频磁浮俘能器俘能试验

振动能量俘获是获取可再生的清洁能源一种有效途径，具有广阔的应用前景，有利于社会的可持续性发展。目前，随机功率谱激励下的高功率密度和宽频能量回收仍然是研究的难点。该研究设计了一种可有效利用宽频振动能量的高功率密度磁浮式俘能器，采用COMSOL Multiphysics软件计算悬浮磁体非线性回复力与位移的关系式，根据磁浮振动系统的控制方程和基尔霍夫定律建立俘能器的数学模型，详细研究了模型参数变化对俘能器性能的影响。随后进行正弦扫频和驻频试验以验证俘能器的发电能力。同时，从俘能器的效率、效能和体积优质3个指标对俘能性能进行评价；并结合实际应用，设计俘能器稳压电路。根据丘陵山区农业机械工作的随机路谱特性，建立随机激励的数学模型，根据响应幅值的概率密度函数的FPK方程表达式，得到了平稳概率密度函数的解。结果表明：在激励频率从9.77到31.75 Hz变化时，俘能器最大输出电压在5.92和21.52 V之间；最大输出功率在10 Hz时达81.93 mW，从5到50Hz，输出功率范围为5.76到81.93 mW；俘能器的效率、效能和体积优质分别为2.85%，9.85%和39.74%；俘能器电压输出的功率谱密度有5个峰值点，对应频率分别为9.804、29.41、36.76、36.76、51.47和71.08 Hz，进一步验证了该研究提出的磁浮式俘能器具有宽频发电性能，并可满足丘陵山区农机设备监测传感器的供电需求。     

Realizing the potential of trait‐based approaches to advance fisheries science

Analysing how fish populations and their ecological communities respond to perturbations such as fishing and environmental variation is crucial to fisheries science. Researchers often predict fish population dynamics using species‐level life‐history parameters that are treated as fixed over time, while ignoring the impact of intraspecific variation on ecosystem dynamics. However, there is increasing recognition of the need to include processes operating at ecosystem levels (changes in drivers of productivity) while also accounting for variation over space, time and among individuals. To address similar challenges, community ecologists studying plants, insects and other taxa increasingly measure phenotypic characteristics of individual animals that affect fitness or ecological function (termed “functional traits”). Here, we review the history of trait‐based methods in fish and other taxa, and argue that fisheries science could see benefits by integrating trait‐based approaches within existing fisheries analyses. We argue that measuring and modelling functional traits can improve estimates of population and community dynamics, and rapidly detect responses to fishing and environmental drivers. We support this claim using three concrete examples: how trait‐based approaches could account for time‐varying parameters in population models; improve fisheries management and harvest control rules; and inform size‐based models of marine communities. We then present a step‐by‐step primer for how trait‐based methods could be adapted to complement existing models and analyses in fisheries science. Finally, we call for the creation and expansion of publicly available trait databases to facilitate adapting trait‐based methods in fisheries science, to complement existing public databases of life‐history parameters for marine organisms.