水泥稳定碎石的试验分析

介绍了公路水泥稳定碎石的原材料、配合比设计及通过试验利用当地材料配制水泥稳定碎石,并对它的强度、干缩应变进行试验分析。     

基于S7-300PLC和PPU的远洋渔船船舶电站控制系统设计

基于S7-300可编程逻辑控制器(PLC)和船舶电站发电机并车与保护单元(PPU),设计了远洋渔船船舶电站智能化控制系统。以PLC为主站、PPU为从站组成的联合控制核心,采集发电柴油机组以及船舶电网的各项参数,实现输入、输出共享,并根据设置的参数进行智能化指令执行。满足船舶电站自动控制以及安全保护等功能,适应渔船在航行及作业过程中工况多变的特点,从而提高船舶电力网的可靠性、便利性与经济性。     

公路交通安全性改进技术研究

在总结国内外现有研究成果和工程经验的基础上,对公路交通安全性改进中涉及的核心技术进行了研究,包括安全问题的诊断程序、安全改进方案的经济效益分析以及安全改进地点和改进方案的选择。结果表明：采用双变量区间过滤法可以方便、快捷地找出安全改进地点;我国事故成本由伤亡成本、车辆损失、路产损失、社会机构损失、交通延误损失等5部分构成,并采用数理统计的方法得到了2006年度平均事故成本为272305元;采用0-1整数规划可以在改善资金受约束的条件下选择经济效益最大化的安全改进地点和改进方案。文章最后给出了应用示例。     

两自由度系统的自由振动实验

汽车行驶过程中会因为地面不平引起的冲击载荷、发动机工作的振动等原因而产生振动,当汽车振动的频率与车身固有频率相接近时,车身会产生很大的垂向加速度,不仅会使驾乘人员感到不适,还会造成车身结构的损坏。因此,对于汽车振动模型的研究就显得尤其重要。以搭建的两自由度系统的试验模型为研究对象,求得其在不同初始条件下实验的自由振动响应,来验证理论求解模型的正确性,为汽车平顺性的改善提供理论依据。     

基于STAR-CCM+的潜艇周围复杂流场数值模拟

为研究潜艇周围复杂的流场分布,本文基于STAR-CCM+软件平台,结合SST k-?模型,通过求解Navier-Stokes方程,分别对均匀来流以及非均匀来流这两种来流方式下潜艇做直航运动以及斜航运动这四种工况下的周围流场进行数值模拟.首先计算了均匀来流下潜艇做直航运动时不同航速下的阻力以及表面不同位置处压力系数及摩擦阻力系数分布,与实验结果符合良好.接下来对四种工况下潜艇周围流场中的漩涡分布,尤其对位于指挥台围壳与尾翼这些附体附近区域的漩涡分布进行了分析,同时还计算了非均匀来流情况不同速度分布形式下潜艇的受力以及力矩,为潜艇平台回收AUV时路线选择提供参考.     

道路交通事故灰色预测模型的建构与应用研究

分析了我国当前交通安全形势的严峻性,说明了道路交通事故预测技术的重要性.在对比两种传统的交通事故预测模型的基础上,分析了灰色模型在交通事故预测中的优越性,并构建GM(1,1)对道路交通事故量进行了预测,结果证明是可信的.     

Hydrographic structure and zooplankton abundance and diversity off Paita, northern Peru (1994 to 2004) — ENSO effects, trends and changes

The objective of the present study was to verify possible spatial, seasonal, and inter-annual changes in the zooplankton off Paita (northern Peru), an upwelling area located closely to the limits of cold Humboldt Current and warm Equatorial Surface Waters. Zooplankton was sampled at subsurface on 53 occasions from August 1994 to December 2004 at four stations located 2 to 30 km offshore with a WP-2 net (300 µm). Extremely high surface water temperatures combined with low salinities were observed during the 1997/98 El Niño up to 29.0 °C) and in April 2002 (up to 25.0 °C). Temperatures more than 2 °C above monthly average were also observed in October 1994, in April 2000, and in November 2004. Significant trends were observed for oxygen concentration (increase) and several horizontal and vertical gradients. Among the copepods (72% of all individuals), the most abundant species were Paracalanus parvus (28%), Acartia tonsa (26%), and Calanus sp. (10%). The strong 1997–98 El Niño (EN) event led to drastic changes in species composition that were reversed during the 1998–99 La Niña (LN) event. Community parameters such as total abundance, diversity, equitability and species richness displayed marked variations associated with the 1997–98 EN and long-term trends. Long-term trends were significant for several vertical and horizontal temperature and oxygen gradients, indicating an increase in upwelling intensity at the shelf during the study period. 10-year-trends were also significant for total zooplankton abundance (increase) and community evenness (J, decline). Our data confirmed the importance of the weak EN in 2002/03 for the study region. Within the trend of increasing zooplankton abundance, a sharp step or shift was observed from 1999 to 2000. When using sequential t-tests to detect shifts in (x + 1) transformed abundance data, a significant rupture was found between the last sampling in 1999 and the first sampling in 2000. Also, a substantial decrease in diel variability occurred after 1999, probably due to changes in vertical migration patterns. The considerable increase in zooplankton abundance over the study period, the ENSO effect, and the 1999–2000 transition are discussed with regard to synchronicity with other zooplankton time series. The present study contributes with the first evidence from an important area located in the Humboldt Current for synchronous trends and changes that were previously observed elsewhere in the Pacific. Our results demonstrated the importance of long-term zooplankton monitoring studies in upwelling areas, and confirms the idea of dramatic changes in pelagic ecosystem structure occurring in the East Pacific.     

某型舰船轴承密封装置防泄漏改进设计研究

针对当前某型舰船主柴油机输出端、主轴支撑点及柴油发电机主轴等处轴承密封圈出现的严重泄漏润滑油问题,分析了泄漏原因,拟设计采用新型多级泄压式密封技术实验型轴承密封圈以替换目前单级轴承密封装置,从而达到防止轴承润滑油泄漏的目的,并满足现有轴承和轴系结构尺寸的情况下,实现无抽轴不解体修复与更换。     

基于DS18820的多路温度采集系统

提出了基于采用DS18820和AT89C51单片机组成的单总线多路温度检测系统,详细给出了硬件和软件系统的设计过程。该系统设计可靠性高、性价比高,在智能化自动检测和控制系统中具有广阔的前景。     

“南海一号”打捞过程中的水下定位和姿态监测

"南海一号"是我国2007年底在广东阳江水域打捞出水的一条宋代沉船。为了更好地保护该船,打捞过程采用了"整体打捞"技术方案。为了保证打捞中水下定位和提升过程姿态检测准确无误,天津水运工程科学研究所将国际上最先进的姿态传感器和水下超短基线定位系统成功应用于"南海一号"打捞的定位和姿态监测过程中,为成功打捞沉船提供了重要的技术和安全保障。文章介绍了打捞的技术难点、技术方案和打捞过程。