A Bayesian structural model for predicting algal blooms

A Bayesian structural model with two components is proposed to forecast the occurrence of algal blooms, multivariate mean‐reverting diffusion process (MMRD), and a binary probit model with latent Markov regime‐switching process (BPMRS). The model has three features: (a) forecast of the occurrence probability of algal bloom is directly based on oceanographic parameters, not the forecasting of special indicators in traditional approaches, such as phytoplankton or chlorophyll‐a; (b) augmentation of daily oceanographic parameters from the data collected every 2 weeks is based on MMRD. The proposed method solves the problem of unavailability of daily oceanographic parameters in practice; (c) BPMRS captures the unobservable factors which affect algal bloom occurrence and therefore improve forecast accuracy. We use panel data collected in Tolo Harbour, Hong Kong, to validate the model. The model demonstrates good forecasting for out‐of‐sample rolling forecasts, especially for algal bloom appearing for a longer period, which severely damages fisheries and the marine environment.     

银杏幼树环剥倒贴皮促花促果试验研究

通过对生长旺盛的3~5年生银杏幼树连续3年的环剥倒贴皮试验研究,结论证明,该项技术促花效果非常显著,豫南大别山区的银杏幼树环剥时间以花芽分化前的5月底至6月初为宜.     

EPM处理Q235钢方坯热加工后组织与性能

通过对电脉冲孕育（ＥＰＭ）处理和未经处理的Ｑ２３５钢连铸小方坯热加工后组织及性能的比较，研究了经ＥＰＭ自理后改善和细化了的凝固组织对热加工后组织和性能的影响，研究结果表明，经ＥＰＭ处理后的Ｑ２３５钢连铸小方坯铸造。热处理后的组织均匀，比未经处理钢的晶粒更为细小，晶粒尺寸由４０μ冯小到２０μｍ；提高了６．９％，值提高了１０％。     

超声除藻的参数优化及其在太湖除藻中的应用

设计、制备了一种低频超声除藻装置,通过调节超声频率、功率和辐射时间等不同的参数,得到优化的超声参数组合,并将该技术应用于太湖除藻的现场研究.结果表明:当超声参数组合为频率20 kHz,功率40 W,辐射时间15 s时,具有较好的实验除藻效果.在太湖现场实验中,载有超声除藻装置的实验船在400 m2实验区域作用1 h后,水表层的藻细胞由107个/mL降低到105个/mL,透明度由0 cm上升为35 cm,叶绿素a含量降低为初始浓度的3.3%,水质得到明显改善.这说明超声处理对藻类生长有显著的抑制作用,尤其适于水华发生期间的应急处理.     

VANET 中一种可撤销的车辆群组批认证方法

针对车辆认证的效率瓶颈问题,本文提出了一个群组安全通信方案.该方案运用批认证的方法来加快群组中车辆的认证速度,而在群组的构建过程中,采用无证书的公钥密码体制来克服密钥托管问题;对于群组中不合法车辆的撤销问题,采用布隆过滤器快速、低存储的特性来对撤销的车辆信息进行公布,避免以往使用撤销链表时所需的巨大存储开销和认证时延.仿真发现所设计的方案在计算时延和传输开销方面都优于现存方案.     

BP神经网络水华预测模型的敏感性分析

敏感性分析能够定量地评价模型输入变量的变化对输出结果产生的影响,是揭示模型蕴含规律的有效途径.本文将敏感分析方法应用于BP神经网络巢湖水华预测模型中,分析结果表明巢湖水华形成受诸多环境因子共同影响,水温、溶解氧、浊度、气温、光照强度等环境因子变化与藻类质量浓度变化相关,其中气温是最大影响因素,相对贡献率达到17.01%;气压的上升则不利用于藻类质量浓度的增加;pH值的上升对藻类质量浓度的影响有正有负.     

Remote sensing of algal blooms using a turbidity-free function for near-infrared and red signals

HARMFUL ALGAL BLOOM ACTS UPON IMPORTANT ENVIRON-MENTAL PROBLEMS IN COASTAL WATERS.A UNIFIED AND IM-PLEMENTING METHOD FOR SURVEY AND MONITORING ALGALBLOOMS HAS BEEN DEVELOPED SINCE LAST DECADE.HOWEVER THERE IS A DATA GAP OF ABOUT TENS YEARS IN THE PERIOD W…     

基于WebGIS技术的海洋环境在线监测信息系统

在对海洋环境监测系统数据发布进行全面需求分析的基础上，引入WebGIS信息建立发布平台．该平台不但充分发挥了WebGIS的属性信息的发布和检索功能，而且整合了监测数据的实时聚类分析，对有害藻类密度进行预测．GIS结合互联网技术，扩大了传统地理信息发布平台的信息发布范围，直观而又高效地实现了海洋环境监测系统监测数据的网络共享．     

分布式环境下改进的Bloom Filter过滤技术

分析了Bloom Filter技术在特殊的分布式系统———P2P系统中的应用.基于Bloom Filter提出了一种新的Division Bloom Filter(DBF)技术,DBF技术采用了一组相互独立的哈希函数来计算数据对象的地址序列,然后使用这组地址序列将数据对象存储到一个分片的位向量中,所以DBF技术可以有效减少数据对象的存储空间.实验证明,DBF不仅可以解决Bloom Filter在分布式环境下的动态更新问题,还可以有效减少BloomFilter的错误率以及改善其稳定性.最后还使用数据压缩技术进一步减少在P2P系统中使用DBF技术的结点间通信代价.     

Direct evidence of phosphorus outbreak release from sediment to overlying water in a large shallow lake caused by strong wind wave disturbance

Concentration variations of suspended solids (SS), total phosphorus (TP), dissolved total phosphorus (DTP), dissolved reactive phosphorus (SRP), and algae available phosphorus (AAP) in overlying water were observed during the coldest week in a year in Lake Taihu, a large shallow lake in China. Water samples at different water depths were collected with wind speeds of 8, 12, 0 and 0 m/s on 23, 24, 26 and 30 January 2004, respectively. On 23 January 2004, SS concentration increased to 258 mg/L with a wind speed of 8 m/s lasting for 1 h. SS concentration kept increasing and reached to 507 mg/L when the strong wind lasted for 24 h and the peak value of wind-speed reached to 12 m/s on 24 January 2004. On 26 January 2004, SS concentrution decreased to 51 mg/L with the wind speed smaller than 2 m/s lasting for about half a day. Then after five continuous waveless days, SS concentration decreased to 21 mg/L on 30 January 2004. The observed results confirmed that sediments in Lake Taihu would be intensively suspended if the surface wind speed is greater than 8 m/s, and the magnitude of SS would increase with increasing wind-speed. Coupled with the intensive sediment suspending, concentrations of TP, DTP and SRP on 23 January were 0.210, 0.048 and 0.035 mg/L, respectively. And they were 0.299, 0.054 and 0.026 mg/L on 24 January, which were significantly higher than those on 26 and 30 January. SRP concentration on 23 January was twice as high as that observed on 30 January. It indicates that the strong wind may result in an outbreak release of phosphorus. Moreover, AAP contents in suspended solids were 132, 97 and 226 mg/kg on 23, 24 and 26 January, respectively. Therefore, it could be estimated that this strong wind process resulted in 987 t of TP, 80 t of SRP and 167 t of AAP releasing from sediments into overlying water. Since such strong wind process is frequent in the area of Lake Taihu, dynamical release driven by wind-induced wave disturbance may be the main mode for internal release of phosphorus. It must have important effects on the nutrient supply during Microcystis bloom in Lake Taihu.