基于渔获群落多样性指标的深水流刺网渔具作业性能分析

根据在东海区开展的3种型深水流刺网选择性试验数据,对3种型深水流网渔获组成、多样性及渔获性能进行了分析比较研究。结果表明:(1)本次试验共捕获33种渔获物,包括鱼类28种、头足类3种、甲壳类2种,其中3种型刺网均捕获种类8种;(2)3种型刺网优势种存在差异,日本方头鱼和黄鲷为共同优势种;(3)3种型刺网捕获种类多样性指数(D值、H’值、J’值)均不存在显著性差异(P>0.05),但渔获种类差异明显,3种型刺网两两比较种类Sorensen相似度均低于50%;(4)同型刺网相邻网目尺寸Bray-Curtis相似性较高,随着网目间距增加,相似度逐渐减低,以重量和尾数计算的相似性基本趋于一致;(5)3种型刺网随网目尺寸的增加(50～70mm),其W统计值(-0.113～0.040)总体上呈现依次增大的趋势,干扰程度逐渐较低。从生态多样性保护角度,增大网目尺寸是目前保护东海区底层生物多样性最有效的方式之一。     

Experimental study on wide-shallow composite bucket foundation for offshore wind turbine under cyclic loading

As an appropriate type of foundation for offshore wind turbines (OWTs), wide-shallow composite bucket foundation (WSCBF) is cost-competitive, and it has a unique and special substructure that comprises seven internal rooms arranged in a honeycomb-like structure. In this study, the cyclic behavior of WSCBF for OWTs embedded in saturated clay was investigated using a large-scale model subjected to lateral cyclic loading. The responses of foundation under constant- and various-amplitude cyclic loadings were recorded in terms of displacements, rotations, and bending moments. The variations in stiffness and damping were obtained, and a collaborative bearing mechanical model between the bucket and soil was considered, which was beneficial for improving the stiffness of the whole structure. Accumulative deformation was found to have little effect on the bearing capacity of the foundation. Dynamic analysis in frequency domain was further performed on both moment and rotation data, and the complex, frequency-dependent impedance was also studied.     

BOC调制信号多径误差分析

针对导航信号的多径误差分析,在多径误差包络曲线分析方法基础上提出了多径误差包络期望分析方法。与包络曲线分析方法相比,包络期望分析方法能够定量分析导航信号多径误差。基于包络期望分析方法,对同码速率的二进制偏移载波(BOC)调制导航信号与二进制相位控键(BPSK)调制导航信号的多径误差进行了对比分析。结果表明,BOC调制导航信号具有更小的典型多径误差。     

音响驯化技术在鲤养殖中的实验研究

探讨淡水养殖尤其是大水域网箱养鱼中由于投饵方式的不当和投饵量过多导致过剩饵料沉积引起水域环境污染的解决方法。本研究利用鱼类的听觉生物学特性,参考音响驯化技术的有关参数,结合投饵用400 Hz正弦波连续音对鲤(Cyprinus carpioLinnaeus)进行了音响驯化实验。结果表明,最初放声时,实验鱼产生惊愕反应,迅速离声源而去;但驯化6 d后,实验鱼在放声后迅速游向声源,摄食时间由最初的150 s缩短到实验后期的60 s。整个实验阶段放声组与对照组摄食时间差异极显著(P<0.01),摄食率和特定生长率无显著差异(P>0.05)。根据实验鱼的生长参数,求得了参考投饵量曲线和方程。本实验结果为音响驯化技术在淡水鱼养殖中的推广应用提供了基础数据。     

海水中液-固界面的台阶型动力学曲线 Ⅱ.液膜扩散-递进扩散-界面分级交换反应联合控制的复合模型理论

为定量解释海水中液-固界面的台阶型动力学曲线及其台阶的消长变化规律,在我们已提出的“液膜扩散和递进液膜扩散控制的复合模型”和“海水中液-固界面分级离子/配位子交换理论”基础上,吸取Crank的若干数学处理方法,进而提出适合于非稳态体系的“液膜扩散-递进扩散-界面分级交换反应联合控制的复合模型”。     

p-y曲线对成层土体中大直径单桩的适用性研究

API规范推荐的p-y曲线是由均质土体得到的,并未考虑土层间相互作用,Georgiadis基于柔性桩提出了等效深度法修正p-y曲线,把均质土p-y曲线延伸到了成层土体中。为了研究p-y曲线和等效深度法对于大直径单桩在成层土体中的适用性,取4种典型地质条件:成层砂土、砂土-黏土-砂土、成层黏土和黏土-砂土-黏土,通过L-PILE软件计算了6 m直径单桩基础的p-y曲线、桩顶水平荷载-位移曲线、桩身位移和弯矩。并与ABAQUS建立的单桩基础三维有限元模型计算结果进行比较。结果表明等效深度法对于成层砂土影响不大;对于成层黏土影响较大;对于中间为软弱土层的成层土体,在荷载较大时影响显著,等效深度法计算结果更加接近FEM结果。在成层土体中,p-y曲线应用于大直径单桩对于砂土高估了初始刚度,低估了极限抗力;对于黏土则低估了初始刚度和极限抗力。     

西沙湾工程波浪推算及波浪场数值模拟

本研究根据崇武水文站1976—2007年共31 a的波浪观测资料,使用皮尔逊Ⅲ型频率曲线进行拟合分析,推算出崇武在不同重现期条件下的特征波浪要素,再将其作为外海波浪要素输入,通过基于椭圆型缓坡方程的CGWAVE近岸波浪数值模型,模拟西沙湾的重现期波浪场,得到其设计波浪要素,得到较为合理的计算结果。西沙湾的海底地形强烈地影响近岸波浪,导致了波高和波向的不均匀分布特征,岛屿和礁石都是天然屏障,东侧水域受龟屿及闽台码头的掩护,波浪反射、绕射明显,对避风坞起到了有效的保护作用。此外,对于不同地质的边界,反射系数不同使得近岸波高分布有较大差异。     

Development of the cyclic p–y curve for a single pile in sandy soil

Pile foundations that support transmission towers or offshore structures are dominantly subjected to cyclic lateral load induced by wind and waves. For a successful design, it is crucial to investigate the effect of cyclic lateral loads on the pile behavior that is loaded laterally. Although the p–y curve method is generally utilized to design the cyclic laterally loaded pile foundations, the effect of cyclic lateral loads on the pile has not been properly implemented with the p–y curve. This reflects a lack of consideration of the overall stiffness change in soil–pile interaction. To address this, a series of model pile tests were conducted in this study on a preinstalled aluminum flexible pile under various sandy soil conditions. The test results were used to investigate the effect of cyclic lateral loads on the p–y behavior. The cyclic p–y curve, which properly takes into account this effect, was developed as a hyperbolic function. Pseudo-static analysis was also conducted with the proposed cyclic p–y curve, which showed that it was able to properly simulate cyclic laterally loaded pile behavior in sandy soil.     

An interconnect width and spacing optimization model considering scattering effect

As the feature size of the CMOS integrated circuit continues to shrink, the more and more serious scattering effect has a serious impact on interconnection performance, such as delay and bandwidth. Based on the impact of the scattering effect on latency and bandwidth, this paper first presents the quality-factor model which optimises latency and bandwidth effectively with the consideration of the scattering effect. Then we obtain the analytical model of line width and spacing with application of curve-fitting method. The proposed model has been verified and compared based on the nano-scale CMOS technology. This optimisation model algorithm is simple and can be applied to the interconnection system optimal design of nano-scale integrated circuits.     

基于空间公平理论的公共交通服务评价——以深圳市为例

使用空间无关的公平性衡量指数评价公交服务时,会忽视公交服务需求与供给的空间分布特征.为解决此问题,论文提出基于空间公平理论的公交服务评价框架,即通过构建综合基尼系数与莫兰指数的空间公平评价方法,实现整体尺度公交服务评价;通过对分析单元上相对需求与相对供给变量的匹配关系、空间差距进行分析,实现局部尺度公交服务评价,对整体...