First documentation of spawning by deepwater sculpins in the Great Lakes and potential impacts of round gobies

Deepwater sculpins Myoxocephalus thompsonii, formerly fourhorn sculpin M. quadricornis (marine form), inhabit all five Great Lakes. Deepwater sculpin is prey for lake trout Salvelinus namaycush and feeds on benthos. Populations have been declining with possible reasons being oligotrophication, quagga mussels (Dreissena bugensis), predation, and impacts of round goby Neogobius melanostomus competition or predation on eggs. Deepwater sculpins are thought to spawn during winter based on gravid females and appearance of larval fish in spring, but a male guarding a nest has not been documented. We used remotely operated vehicle technology during December 2015, March 2017, and March 2021 in 70–191 m in Grand Traverse Bay, Lake Michigan to identify the distribution of deepwater sculpins, round gobies, and nests with a guarding male. Round gobies were much more abundant (observations/hr = 139) in water < 125 m than were deepwater sculpins (11/hr), while in water > 166 m, deepwater sculpins were much more common (39/hr) than at shallow sites. At deep sites, round gobies were more abundant (51/hr) than deepwater sculpins (39/hr). On 16 March 2021 in 190 m of 1.9 C surface water we discovered several presumptive, unoccupied nests, but one nest in a depression next to a branch contained a deepwater sculpin and a clump of eggs. This is first evidence of where and how deepwater sculpins spawn. We also documented round gobies in the same area with one within 2 m of the nest, creating the possibility for consumption of eggs potentially affecting their long-term survival.     

基于四自由度视觉机器人的织物分拣方法

针对人工分拣织物效率低,劳动成本高,而且对工人身体产生危害的问题,提出机器视觉与机器人相结合代替人工分拣织物的方法,从而解决了人工分拣织物存在的缺陷。构造RBF神经网络的颜色分类器将不同颜色织物分类,利用阈值分割对目标织物进行分割;使用遍历中心扩散法求取机器人抓取织物的抓取点;经过摄像机标定和机器人轨迹规划实现机器人对纯色织物的自主分拣。实验结果表明,该方法分拣织物的准确率能够满足纺织业的实际应用需求。     

矿井大型导线控制网双观测平差模型

矿井导线网平差的特点是2类观测值（测角和量边）数量相当,多余观测量相对较少。为了提高矿井大型导线控制网的平差精度,根据矿井导线控制网往返观测及验后估计需要多余观测数较多的特点,提出了双观测平差模型。相对于经典平差模型,该模型条件方程个数较多,容易满足验后估计的可估条件,从而可通过后验估计合理定权来提高矿井大型导线控制网的平差精度。以某矿井大型导线控制网的实测数据为例进行了平差计算,结果显示：经典平差模型求得的3条已知边的方位角平差值与真值之差依次为-7″、-62″、-54″,而新提出的双观测平差模型所得出的平差值与真值之差依次为-10″、-12″、-15″,这说明双观测平差模型通过Helmert方差估计能够合理定权,可更准确地计算出各网点的平差值,具有一定的实用性。     

导线测量法在输电线路测量中应用及其精度分析

探讨导线定线法及在输电线路测量中的应用.     

磨料水射流切割面粗糙度研究

对在磨料水射流切割过程中进给速度和磨料流量两点进行了讨论。磨料颗粒采用直径为80目的石榴石。测量了切割不同深度的粗糙度。实验结果表明:对切割表面影响最大的是切割速度。同时也研究了切割面粗糙度和磨料水射流其他参数之间的关系。     

减少特长隧洞横向贯通误差的地下导线探讨

本文就长隧洞的地下导线的布设提出了一些新的方法，并就地下导线的设计方法及减低横向贯通误差提出了一些措施。     

青泽紧密纺纱机技术特点及应用实践

探讨德国青泽700型紧密纺纱装置以及相关工艺参数配置.介绍了紧密纺纱机的结构与性能特点.通过合理配置前纺各工序纺纱工艺及采取有关技术措施,并对紧密纺纱机集聚负压和粗纱横动等工艺参数进行了试验与优选,结果使CJ 7.3 tex紧密纺纱质量达到了较好的水平.     

EB型自动缫丝机络交机构剖析

该络交机构借助子一对偏心齿轮的啮合传动,来带动装在摇臂上的一只蜗杆和两只蜗轮,与其各自相连接的两只端面移距凸轮的相对转动,成为一种具有特殊结构型式的复式络交机构。卷绕后的丝片具有厚薄均匀,成形良好的特点。     

基于高速缓存系统的遍历查询研究与设计

由于大型网站具有高负载和高并发的特点,Memcached作为一种解决方案在缓存数据量较大的情况下,使用Memcached的命令组合方式遍历缓存无法完成对所有有效数据的查询。本文针对这个方面研究并设计了缓存数据遍历方案,通过对Memcached客户端的应用研究与模拟实现,很好的解决的这个问题。     

无定向角导线(网)布设的探讨

对无定向角导线的精度进行了刍议,通过分析对最弱点点位中误差的影响因素,分别对附合导线、单定向角导线和无定向角导线最弱点点位中误差的计算比较,探讨了无定向角导线(网)布设的可行性