拉绳式电子测径尺的研发及其测径效果分析

【目的】开发一种拉绳式电子测径尺，以解决围测类测径仪器因柔性尺面宽度而影响测量精度的问题，同时实现林木胸径外业数据的高效采集和内业高效记录。【方法】基于经典围测原理，以钢绳、卷盘、无刷直流电机和光电编码器为主要结构,研发了拉绳式电子测径尺。以钢尺测得的样木圆盘直径（8个方向测量）均值作为真值，利用拉绳式电子测径尺、柔性尺面电子测径尺、围尺和卡尺（2个方向测量），分别测量了20个近似圆形胸高圆盘（规则圆盘）的直径和20个不规则胸高圆盘的直径，比较各仪器测径的方差、准确度和t检验结果；用4种仪器分别测量7号样木规则圆盘直径和27号样木不规则圆盘直径，连续测6次,比较各仪器测径的精密度；用4种仪器分别测定10个规则圆盘和10个不规则圆盘的直径，记录平均耗时，比较各仪器的测径效率。【结果】拉绳式电子测径尺、柔性尺面电子测径仪、围尺和卡尺测量规则圆盘直径的准确度分别为0.045，0.205，0.115和0.140 cm，精密度分别为0.017，0.067，0.067和0.200 cm，方差分别为33.267，33.401，33.532和33.443；测量不规则圆盘直径的准确度分别为0.120，0.295，0.205和0.280 cm，精密度分别为0.058，0.092，0.067和0.350 cm，方差分别为22.525，22.908，22.611和21.607；测径平均耗时分别为6.9，7.5，7.7和13.9 s。【结论】拉绳式电子测径尺的测量精度和测径效率均优于柔性尺面电子测径仪、围尺和卡尺，不仅可满足森林资源连续清查和森林资源规划设计调查的精度要求，还能大大缩减外业测量和内业录入的成本。     

Toxicity and horizontal transfer of bifenthrin and dimefluthrin against the red imported fire ant,Solenopsis invicta Buren (Hymenoptera: Formicidae), and the efficacy of their dust applications in the field

The red imported fire ant, Solenopsis invicta Buren, poses a significant threat to biodiversity, agriculture, and public health in its introduced ranges. While chemicals such as toxic baits and dust are the main methods for S. invicta control, toxic baits are slow, requiring approximately one or two weeks, but dust can eliminate the colony of fire ants rapidly in just three to five days. To explore more active ingredients for fire ant control using dusts, the toxicity of bifenthrin and dimefluthrin, the horizontal transfer of bifenthrin and dimefluthrin dust and their efficacy in the field were tested. The results showed that the LD₅₀ (lethal dose) values of bifenthrin and dimefluthrin were 3.40 and 1.57 ng/ant, respectively. The KT₅₀ (median knockdown time) and KT₉₅ (95% knockdown time) values of a 20 μg mL^–1 bifenthrin dose were 7.179 and 16.611 min, respectively. The KT₅₀ and KT₉₅ of a 5 μg mL^–1 dimefluthrin dose were 1.538 and 2.825 min, respectively. The horizontal transfers of bifenthrin and dimefluthrin among workers were effective. The mortality of recipients (secondary mortality) and secondary recipients (tertiary mortality) were both over 80% at 48 h after 0.25, 0.50 and 1.00% bifenthrin dust treatments. The secondary mortality of recipients was over 99% at 48 h after 0.25, 0.50 and 1.00% dimefluthrin dust treatments, but the tertiary mortality was below 20%. The field trial results showed that both bifenthrin and dimefluthrin exhibited excellent fire ant control effects, and the comprehensive control effects of 1.00% bifenthrin and dimefluthrin dusts at 14 d post-treatment were 95.87 and 85.70%, respectively.     

助剂380对杀菌剂在芒果叶片上展着能力的影响

当今现有农药利用率低造成一系列社会问题,如非靶标生物和人畜安全受影响,以及环境污染等。如何提高现有农药的利用率迫在眉睫。为提高芒果生产中杀菌剂的有效利用率,结合芒果的特性,研究添加农药助剂对杀菌剂在芒果叶片上润湿展布性和农药持留量的影响,为农药的高效利用提供理论指导。本研究以防治芒果细菌性角斑病的杀菌剂为研究对象,通过测定液体在芒果叶片的接触角及不同浓度液体的表面张力,根据表面张力及接触角结果,获取芒果叶片的临界表面张力以及助剂的临界胶束浓度（critical micelle concentration, CMC）。通过添加助剂,分析其对药液在芒果叶片表面上展布和最大持留量（maximum retention, Rm）的影响。本研究中,助剂380从实验室前期研究基础上筛选得到,结果表明,助剂380可以降低药液表面张力,增加药液在叶面的润湿展布,对常用细菌性角斑病防治药剂表面张力值的降低范围为23.54%~75.94%,最低可达(17.62±0.65)mN/m,低于芒果叶片的临界表面张力;且加入助剂的药液能很好地在芒果叶面上展布,在芒果叶上的持留量显著增加,最大增加率为203.53%。因此,在芒果细菌性角斑病防治过程中,可以通过添加助剂380来提升药液在作物叶面的展布效果和持液量,从而提高农药的利用率。     

Efficacy and rates of diquat for reducing invasive knotweeds and potential for sequential use with imazapyr

Invasive knotweeds (Reynoutria spp.) pose an ongoing challenge for weed management programs worldwide, requiring years of persistent treatment. In this study, we tested efficacy of diquat applied as foliar spray early in the growing season for short-term suppression, and for potential to boost long-term control when applied sequentially with a mid-season treatment of imazapyr. We evaluated responses of knotweeds (R. japonica, R. × bohemica, and R. sachelinensis) treated with one of three diquat concentrations (0.25%, 0.50%, or 1.0%, v/v), using multiple metrics to capture changes in aboveground plant density and abundance. Canopy cover and biomass were significantly reduced by all diquat concentrations and resembled pre-treatment conditions at 8WAT, reflecting the shift toward reduced stem heights in treated compared with untreated plots. Stem counts at 8WAT, however, did not differ in response to diquat treatments. Sequentially applied early-season diquat and mid-season imazapyr treatments reduced canopy cover (66%–82%), biomass (65%–91%), and stem density (57%–79%) when evaluated 1 year after treatment; reductions were greatest in plots treated with medium and high diquat concentrations, suggesting that diquat treatments may have an additive effect. Overall, our study establishes rates of diquat to reduce biomass of invasive knotweed, and supports additional testing to assess improvement in long-term control when used sequentially with a systemic herbicide.     

双低油菜籽粒离散元仿真参数标定与试验验证

为设计优化双低油菜机械化精量播种设备，以甘肃地区种植的双低油菜，‘青杂5号’和‘陇油19号’籽粒为对象，采用物理试验法测定2种双低油菜籽粒的基本物理学参数以及种子与PLA塑料和光敏树脂间的静摩擦因数和碰撞恢复系数。基于EDEM仿真软件和斜面滚动法，标定种子与PLA塑料和光敏树脂间的滚动摩擦因数，采用仿真逼近预测法标定种子间的滚动摩擦因数，并利用异形槽口窝眼轮排种器台架试验对仿真参数进行验证。结果表明:‘青杂5号’与PLA塑料和光敏树脂间的静摩擦因数分别为0.35和0.34，碰撞恢复系数分别为0.639和0.655，滚动摩擦因数分别为0.064和0.060。‘陇油19号’与PLA塑料和光敏树脂间的静摩擦因数分别为0.32和0.28，碰撞恢复系数分别为0.662和0.666，滚动摩擦因数分别为0.059和0.058。2个品种油菜籽粒间的静摩擦因数分别为0.57和0.59，碰撞恢复系数分别为0.384和0.397，滚动摩擦因数分别为0.054和0.046。将2种品种油菜籽粒的标定参数进行异形槽口窝眼轮排种器仿真试验和台架验证试验，对于‘青杂5号’油菜籽粒，其仿真试验与台架试验合格率的相对误差为0.48%，重播率的相对误差为4.99%，漏播率的相对误差为6.98%。对于‘陇油19号’油菜籽粒，其仿真试验与台架试验合格率的相对误差为0.29%，重播率的相对误差为3.79%，漏播率的相对误差为4.76%。     

横向正应变对梁接触问题的影响

应用深梁理论，分析了受均布荷载悬臂梁与刚性地基接触的全过程。消队 了接触区间端占的集中反力，其接触区间明显大于只考虑剪切变形的梁理论的结果，揭示了横正应对梁的接触问题有着不可忽略的影响。     

高压供电线路故障定位系统的无线传输网络设计

针对现行规范在计算高强度螺栓承压型连接的抗剪承载力时不考虑连接板之间的摩擦力，与承压型高强螺栓的受力机理不相符的问题，采用虚功原理推导了预拉力模拟方法，并采用有限元方法对这一连接的受力过程进行分析.分析结果表明，当连接的承载力由螺栓强度控制时,若不考虑构件间的摩擦力, 则高强螺栓承压型连接的承载力会被低估.在数值分析的基础上对这种连接方式的抗剪承载力提出了考虑连接板间摩擦力的计算方法.与有限元结果比较,该计算方法的误差在10%以内.     

空气与水顺流直接接触热质交换过程模型计算及分析

为了获得方便计算空气与水顺流直接接触热质交换过程的公式和方法,为蒸发冷却设备的设计和实验分析提供了理论指导和新方法,该文基于模型假设和对空气与水顺流直接接触热质交换过程的能量分析,推导出了揭示空气与水顺流进行热质交换时,空气与水的状态参数与过程的无因次量-传质单元数NTU_m、传热单数元数NTU_h和水气比β之间内在规律的通用方程组,并给出了利用MATLAB软件求解方程组的计算方法。应用到绝热等焓过程,理论结果与前人的理论推导结论相同。对一冷却减湿过程进行计算和分析表明,在空气与水进口状态参数一定的情况下,过程的NTU_m、NTU_h、β之间存在相互联系的内在关系;顺流时,进口条件一定,β有一最小值;当β一定时,NTU_m增加到一定值后,对热质交换过程已基本没有影响;当NTU_m一定时,有一最佳β值,此时空气温降最大。     

LmNotch基因在飞蝗翅发育中的功能分析

Notch是Notch信号通路中的受体蛋白,与配体结合后调控下游靶标基因的表达,在无脊椎动物和脊椎动物的发育和分化过程中发挥着重要的作用。本文以飞蝗为研究对象,利用转录组数据库搜索获得Notch信号通路受体基因LmNotch,并利用qRT-PCR对5龄飞蝗不同组织及不同发育时期翅芽组织中的LmNotch表达特性进行了分析。通过RNA干扰试验对其生物学功能进行分析,发现注射dsLmNotch的飞蝗有70%无法完成蜕皮过程,10%的飞蝗在蜕皮后出现翅紊乱表型。飞蝗翅芽石蜡切片的H&E染色结果表明,处理组翅上下两层表皮之间腔空间增大,新表皮无法完整形成。qRT-PCR检测其他翅发育相关基因表达发现,LmNotch表达量的下降影响翅发育相关基因Dpp、Omb、Yorkie以及翅特异表皮蛋白基因的表达。上述研究结果可为昆虫翅发育机制研究提供理论基础,同时为害虫生物防治提供潜在靶标。     

基于接触摩擦的变截面钢板弹簧悬架性能分析

传统钢板弹簧分析只是采用简化力学模型，而没有考虑簧片间的摩擦.为了更好地对少片变截面钢板弹簧进行设计，本文首先对少片变截面钢板弹簧悬架进行参数化建模.然后应用接触理论添加接触单元，来模拟钢板弹簧间的摩擦，进行钢板弹簧悬架的有限元计算，得到钢板弹簧悬架的装配预应力、刚度和阻尼特性的仿真值.与由传统预应力计算方法得到的结果和行业推荐值进行比较分析，证明基于接触摩擦的少片变截面钢板弹簧悬架性能分析的方法更能反映簧片实际的受力情况.