Tributary use and large-scale movements of grass carp in Lake Erie

Infrequent captures of invasive, non-native grass carp (Ctenopharyngodon idella) have occurred in Lake Erie over the last 30+ years, with recent evidence suggesting wild reproduction in the lake’s western basin (WB) is occurring. Information on grass carp movements in the Laurentian Great Lakes is lacking, but an improved understanding of large-scale movements and potential areas of aggregation will help inform control strategies and risk assessment if grass carp spread to other parts of Lake Erie and other Great Lakes. Twenty-three grass carp captured in Lake Erie’s WB were implanted with acoustic transmitters and released. Movements were monitored with acoustic receivers deployed throughout Lake Erie and elsewhere in the Great Lakes. Grass carp dispersed up to 236 km, with approximately 25% of fish dispersing greater than 100 km from their release location. Mean daily movements ranged from <0.01 to 2.49 km/day, with the highest daily averages occurring in the spring and summer. The Sandusky, Detroit, and Maumee Rivers, and Plum Creek were the most heavily used WB tributaries. Seventeen percent of grass carp moved into Lake Erie’s central or eastern basins, although all fish eventually returned to the WB. One fish emigrated from Lake Erie through the Huron-Erie Corridor and into Lake Huron. Based on our results, past assessments may have underestimated the potential for grass carp to spread in the Great Lakes. We recommend focusing grass carp control efforts on Sandusky River and Plum Creek given their high use by tagged fish, and secondarily on Maumee and Detroit Rivers.     

Evidence of successful river spawning by lake trout (Salvelinus namaycush) in the Lower Niagara River,Lake Ontario

Restoration of a wild-produced lake trout Salvelinus namaycush population in Lake Ontario has not been successful despite the adult population often meeting or exceeding restoration targets. Lack of high-quality spawning habitat in Lake Ontario is suggested as one impediment to recruitment of wild lake trout, although the quantity and location of spawning habitat is poorly understood. If high-quality spawning habitat is limited in Lake Ontario, lake trout may be using uncommon spawning locations such as rivers. Anecdotal angler accounts point to the Niagara River as a lake trout spawning location. To better understand the potential of the Niagara River as a spawning location, egg and juvenile fish collections were conducted 12–14 river kilometers from the mouth of the Niagara River from 2010 to 2012; and mature female lake trout with surgically implanted acoustic tags were monitored from 2015 to 2019. Genetic analyses confirmed 60% of collected eggs and 93% of collected post-hatch juvenile fish in the Niagara River were lake trout. Tagged female lake trout returned to the Niagara River over consecutive years during the spawning season. The short duration of lake trout presence in the river (mean = 56 days/year) suggests female lake trout use the Niagara River primarily for spawning. Diversity in spawning locations may provide lake trout population’s resilience against environmental variability through a portfolio effect. Improved identification of riverine spawning locations, including their overall contribution to wild recruitment, may be a useful tool for managers to restore a wild-produced population of lake trout in Lake Ontario.     

有限遥测速率下卫星遥测数据设计方法研究

针对国内小卫星常用的统一遥测模式,讨论了在遥测速率受限的条件下,分包遥测格式设计应满足的基本条件;定义了分包遥测数据格式设计过程中的包编码损失率,并以此作为包数据格式编码效率的评价函数;分析了分包遥测数据格式设计过程中包长度、包采样周期等参数变化对评价函数的影响,进而给出了分包遥测数据格式设计中的应满足的条件和遵循的原则。     

Factors Influencing Movements of Two Migratory Fishes within the Tailrace of a Large Neotropical Dam and their Implications for Hydropower Impacts

Fish attempting to move upstream through hydroelectric dams can be trapped and killed in turbines. Understanding fish movement patterns can provide useful insights for how to manage dam operations to minimize fish kill in turbines. We evaluated the movements of two migratory fish (Curimba—Prochilodus argenteus and Mandi—Pimelodus maculatus ) using acoustic telemetry in the tailrace of Três Marias Dam (São Francisco River, Brazil) from 31 October 2011 to 16 February 2012. The majority of tagged fish left the tailrace in less than one week; however, some individuals returned, performing several visits to the tailrace. Mandi remained longer in the tailrace than Curimba. The number of visits was influenced by diel period, turbine and spillway discharge. Although the diel period was the only important contributor to the visits performed by Curimba, the movements of Mandi were significantly influenced by three factors. We found that whereas Curimba was predominantly diurnal, Mandi showed nocturnal habits. Additionally, visits of Mandi were significantly greater during higher turbine and spillway discharge. We discuss the implications of these results for understanding fish movements in the Três Marias Dam tailrace and their potential implications for adapting hydroelectric operations to minimize fish kills. Copyright © 2016 John Wiley & Sons, Ltd.     

基于PIC单片机的无线遥测分站设计

针对矿井水文长观孔人工监测方式效率低下的问题,提出了一种基于PIC单片机的无线遥测分站设计方案。该无线遥测分站以dsPIC33FJ64GP204单片机为控制核心,采用GSM技术实现通信功能,能够采集水文长观孔的实时数据,并以短信方式发送至地面中心站。实际应用结果表明,该无线遥测分站能及时提供各水文长观孔的数据信息,有效减少了工作人员的日常维护量。     

三峡水情遥测系统中心站的设计与应用

三峡水情遥测系统中心站在通信组网设计上采用甚高频（VHF）、公共交换电话网络（PSTN）、全球移动通信系统（GSM）、北斗卫星和海事卫星5种通信方式,在系统软件设计上采用了客户／服务器（C／S）的结构模式。实践证明,三峡水情遥测系统中心站既保证了三峡水情遥测系统非常高的畅通率和准确率,又降低了通信成本;既保证了三峡梯级水库调度、防洪、发电和航运的要求,同时还为系统运行维护工作提供了方便。     

iNET的技术框架和应用前景

简要介绍了iNET（增强遥测综合网）的概念、国外的iNET项目计划及iNET的技术路线。重点讨论了iNET的技术框架,包括iNET的体系结构、遥测网络系统、外围设备、外设配置人机接口、网络管理和频谱资源管理等组成部分和iNET的主要功能,探讨了iNET的目标和在航空飞行试验中的应用前景。     

基于2D-DCT变换的MWD遥传信号泵冲干扰消除方法

遥传技术是随钻测量(MWD,measurement while drilling)系统中的一项关键技术,目前大多数MWD系统均采用泥浆脉冲方式进行数据传输.钻井现场噪声环境复杂,特别是泥浆泵的泵冲干扰,其强度较大,如果其频率落入脉冲信号的带内,则会对地面接收信号造成严重干扰.因此若不能对脉冲信号带内的泵冲干扰进行很好的抑制,则会限制遥传系统对各种工况的适应能力.提出了一种基于二维离散余弦变换(2D-DCT)的泵冲干扰消除方法,该方法将地面接收到的一维泥浆压力信号转换为二维信号,然后进行2D-DCT变换,从而能在变换域进行泵冲干扰的消除处理.     

移动终端的设施农业物联网环境监控系统设计

通过使用物联网(IOT)传输协议—消息队列遥测传输(MQTT)协议,将前端硬件、服务器端及移动端连接在一起,完成对设施农业环境的远程实时监控.在系统中,前端硬件以STM32微处理器为核心,由传感器模块、设备控制模块、GPRS模块和电源模块组成,实现数据的采集和传输;服务器端有数据接收、存储、分析的能力,并担任MQTT消息协议中消息生产者和消息管理者的角色;移动终端软件则以Android操作系统为基础开发了应用软件,用户在装有Android系统的移动终端上安装该应用软件,即可查看实时环境情况,发送控制设备指令等.经过测试,整个系统运行稳定、使用简单、实时性高,用户能有效地对设施农业环境进行远程实时监控.     

旋转环境下弱小信号无线遥测系统研制

为了提高直升机风洞试验中桨叶载荷、变距拉杆载荷等旋转弱小信号的测量精度,研制了一套40通道的无线遥测系统.该系统成功解决了高精度测量技术,高精度同步触发技术、高速无线数据通信、大容量数据压缩等关键技术难题,构建了高精度、模块化、小型化、实时无线传输的遥测系统.通过性能测试及试验运行,证明该系统能够提高旋转信号的测量精度及传输的实时性,满足直升机风洞试验等旋转环境下弱小信号的测量.