The Importance of Shallow‐Low Velocity Habitats to Juvenile Fish in the Middle Mississippi River

Habitat management is a crucial aspect of fisheries management. Without knowledge of habitat associations, fisheries scientists are unable to effectively make habitat conservation or restoration recommendations. This becomes especially prominent when trying to manage commercially harvested populations and protect threatened or endangered species. To determine juvenile fishes habitat associations in the Middle Mississippi River, we analysed mini‐trawl catch data of six common juvenile fish species: blue catfish (Ictalurus furcatus), channel catfish (Ictalurus punctatus), channel shiner (Notropis wickliffi), freshwater drum (Aplodinotus grunniens), paddlefish (Polyodon spathula), and shovelnose sturgeon (Scaphirhynchus platorynchus). Overall, we conducted 2251 mini‐trawl sampling efforts between 2002 and 2013, resulting in the capture of 23,742 target specimens. Catch per unit effort was evaluated by structural habitat (i.e. velocity, depth, and substrate). Overall, these data suggest that juvenile fish species are more prevalent in shallow water and slower velocities. Ultimately the information garnered during this evaluation should be incorporated when considering habitat modifications, especially those modifications that impact the availability of shallow‐low velocity habitats. Copyright © 2016 John Wiley & Sons, Ltd.     

水电工程对河流生态系统的胁迫及对策研究

在人类进化史上,人类活动无时无刻地对河流进行着改造,对河流生态系统产生了重要影响,例如修建水坝、渠道、农业活动、林业、采矿业、放牧、娱乐、城市化和外来物种入侵等.就水电工程对河流生态系统的胁迫进行研究,并提出了减轻对河流生态系统胁迫的对策.     

浅谈城市道路平面交叉口渠化设计

交叉口是路网的联结点，是城市交通的咽喉，其设计和使用对道路交通的安全与畅通特别重要。本文论述了城市道路平面交叉口渠化设计原则。以实际案例，通过渠化减少了冲突，控制了交通流，提高了交叉口的通行能力，增进了其安全性。     

对城市道路平面交叉设计的探讨

从交通组织设计的角度出发，广泛参照国内外先进的理论与方法，结合平时工作积累的经验，从交叉口危险点、通行能力、渠化设计的角度进行分析探讨，并提出了一些思路，以供参考。     

Patterns of species richness and introduced species in native freshwater fish faunas of a Mediterranean‐type basin: the Guadiana River (southwest Iberian Peninsula)

In this study, we analysed the factors affecting species richness and introduced species component patterns in native fish faunas of 30 streams of the Middle Basin of the Guadiana River. From a principal component analysis and a stepwise multiple regression analysis performed on a data matrix composed of ten hydrological and biotic variables, we showed that: (1) fish species richness increased with stream length and watershed area, (2) the number of native species in a stream declined as channelizations and river regulation (constructions of dams) are higher, whereas introduced species increased in the same way, (3) the two main negative factors affecting native ichthyofaunas affected dissimilar ecological areas: channelizations, which depend on land‐use intensity of floodplain, mainly occurred in lower reaches of streams, but construction of dams mainly took place in upper sections of rivers, (4) the length of the remaining well‐preserved reaches in a stream appeared to be the only factor accurately predicting native fish species richness, and (5) native fish faunas of small isolated streams are more vulnerable to habitat alteration than those of large streams. Both isolation and fragmentation of populations were recorded, so the conservation status of native and highly endemic fish fauna of the study area is extreme. Protection of the few still extant, well‐preserved small streams and upper reaches, habitat restoration of channeled areas, and inclusion of the need for native fish fauna conservation in long‐term public planning of water use become a priority. Fish communities appear to be a sensitive indicator of biological monitoring to assess environmental degradation. Copyright © 2001 John Wiley & Sons, Ltd.     

光学微腔在微波光子雷达系统中的应用

微波光子雷达通过光子技术辅助可突破传统电子技术瓶颈,实现光子系统集成化是未来微波光子雷达的必然发展趋势。具有超高品质因子的光学微腔得益于其独特的线性和非线性光学特性,可在极小的体积内实现宽带微波信号的光域调控,是集成微波光子雷达系统的关键核心元件,在微波光子滤波、光生微波信号、光子辅助信道化接收和光控波束形成等系统功能单元中都具有重要的应用价值,并且在未来太赫兹雷达、激光雷达等系统中也具有广阔的应用前景。     

城市道路交叉口改造设计分析

阐述了城市道路交叉口改造中渠化设计的必要性,进而分析了城市道路交叉口改造优化设计思路,依托工程实例对城市道路交叉口改造设计进行了论述,以期通过城市道路交叉口的改造设计,提高城市道路交叉口的通行能力。     

浅谈城市道路平面交叉口渠化设计

交叉口是路网的联结点,是城市交通的咽喉,其设计和使用对道路交通的安全与畅通特别重要。本文论述了城市道路平面交叉口渠化设计原则。以实际案例,通过渠化减少了冲突,控制了交通流,提高了交叉口的通行能力,增进了其安全性。     

宽带信道化接收机研究与实现

根据多项滤波器组理论和FFT方法提出并实现50%覆盖的均匀信道化宽带数字接收机。这种宽带数字接收机把整个采样频带划分成若干并行信道输出,使得信号全概率截获,是侦收跳频、突发以及自适应通信信号接收机的理想前端。主要应用于软件无线电的实现和电子战中。主要阐述宽带数字接收机信道化原理、软件仿真和硬件实现,并为实际工程需要设计了算法、程序和硬件平台,实现了0~100 MHz频率范围内8信道的数字信道化。