Development of a recurrent Sigma-Pi neural network rainfall forecasting system in Hong Kong

At the moment, weather forecasting is still an art — the experience and intuition of forecasters play a significant role in determining the quality of forecasting. This paper describes the development of a new approach to rainfall forecasting using neural networks. It deals with the extraction of information from radar images and an evaluation of past rain gauge records to provide shortterm rainfall forecasting. All of the meteorological data were provided by the Royal Observatory of Hong Kong (ROHK). Preprocessing procedures were essential for this neural network rainfall forecasting. The forecast of the rainfall was performed every half an hour so that a storm warning signal can be delivered to the public in advance. The network architecture is based on a recurrent Sigma-Pi network. The results are very promising, and this neural-based rainfall forecasting system is capable of providing a rain storm warning signal to the Hong Kong public one hour ahead.     

江口水电站设计洪水分析研究

在分析芙蓉江流暴雨的洪水特性的基础上，采用多种方法插补展延了洪水资源系列，并充分利用历史洪水调查资料，使设计洪水分析计算采用的资料具有一定的代表性，可靠性，其中坝堤百年一遇设计洪水洪峰流量为12000m^3/s,72h洪量为10.2亿m^3，对江口水电站设计洪水成果，通过与上下游，干支流各站的设计洪水参数及与长江流域的部分大中型水利水电工程设计水成果比较，进行了合理性分析。     

Epoxy paint failure in B-52 fuel tanks: Part II. Influence of DIEGME concentration in the fuel on the failure process

A model has been proposed to explain the failure of the original BMS10-39 epoxy paint on upper vertical surfaces in B-52 fuel tanks. The model involves interaction of the paint with DIEGME, a fuel system ice inhibitor (FSII) in jet fuel, that is distilled from the liquid fuel. In this communication, distillation experiments used to support the model are refined to better match the mass transfer of vapor from fuel in a B-52 fuel tank at close to room temperature. The interaction of these lower temperature distillates with the paint affirms the earlier model. On the basis of these experiments it is proposed that paint failure may be controlled or eliminated by reducing the level of DIEGME in the fuel. Proposed changes in military jet fuel composition are detailed.     

Determination of instantaneous corrosion rates and runoff rates of copper from naturally patinated copper during continuous rain events

Instantaneous corrosion rates of naturally patinated copper of varying age (16 months, 138 and 145 years) have been determined during continuous rain events in the laboratory with electrochemical impedance spectroscopy using a two-electrode cell. The two-electrode cell was found to yield the same information in bulk rainwater as a conventional three-electrode cell.Relatively constant corrosion rates, between 0.2 and 0.6 μm/y, were determined for samples having a two-layer structure with an inner brownish layer of cuprous oxide and an outer greenish layer of basic copper salts (138, 145 years). Samples with cuprous oxide as the dominating phase of the patina (16 months) showed higher and somewhat increasing corrosion rates during a rain event (from 0.6 to 1.2 μm/y). During a continuous rain event, corrosion rates were found to be approximately 10 (brownish patina) and 25 times (greenish patina) lower than corresponding instantaneous runoff rates. The first flush phenomena of the runoff process, with an increased concentration during first flush and a relatively constant concentration during steady state, was indirectly seen as an increase in solution conductivity during the first rain volume followed by relative constant value. The contribution of the concentration in the first flush to the total annual runoff rate was significant for panels having a greenish layer (138, 145 years) whereas it was negligible for panels having a brownish layer (16 months).     

An efficient reliable broadcasting protocol for wireless mobile ad hoc networks

The mobile ad hoc network (MANET) has recently been recognized as an attractive network architecture for wireless communication. Reliable broadcast is an important operation in MANET (e.g., giving orders, searching routes, and notifying important signals). However, using a naive flooding to achieve reliable broadcasting may be very costly, causing a lot of contention, collision, and congestion, to which we refer as the broadcast storm problem. This paper proposes an efficient reliable broadcasting protocol by taking care of the potential broadcast storm problem that could occur in the medium-access level. Existing protocols are either unreliable, or reliable but based on a too costly approach. Our protocol differs from existing protocols by adopting a low-cost broadcast, which does not guarantee reliability, as a basic operation. The reliability is ensured by additional acknowledgement and handshaking. Simulation results do justify the efficiency of the proposed protocol.     

Impacts of green roofs and rain water use on the water balance and groundwater levels in urban areas

Ohne Zusammenfassung

---

Impacts of green roofs and rain water use on the water balance and groundwater levels in urban areas

     

3DGIS环境下雨雪天气实时仿真

3D GIS最重要的特征之一就是虚拟现实表现,其本质是可视化技术与GIS数据库的整合,以满足各种应用如生态农业、灾害预测等方面的需求。以GIS数据库的环境数据和气象数据为基础,通过对雨雪的效果模拟,将GIS气象数据以实时的可视化形式逼真地表现出来。实验方法采用粒子系统,对单个点元赋予利用Photoshop制作的大面积纹理,这样采用的粒子数减少到普通粒子系统的十分之一,渲染速度为普通粒子系统的十倍以上,以较小的系统资源消耗达到了更加实时逼真的效果,对雪的动态堆积和雨水地面效果采用GPU加速3维渲染,原型系统同时能接受用户对实验环境如粒子纹理、雨雪量的设置。提出根据气象数据进行天气模拟的自适应策略,从而更加适应实际应用需要。     

工艺条件对YBCO厚膜基带晶粒取向的影响

用Ｘ射线方法研究了平行于基带表面的Ｎｉ（２０Ｏ），Ｎｉ（１１１），ＮｉＯ（２００）和ＮｉＯ（１１１）晶面的取向分数Ｗ。结果表明，随预热处理温度的提高，虽然Ｗ_（ＮｉＯ（２００））也会随之提高，但是区域重加热处理对提高Ｗ_（ＮｉＯ（２００））起着最重要的作用。９００℃预热处理之后，在１１００℃进行区域重加热可使Ｗ_（ＮｉＯ（２００））提高到０．９９以上。     

Investigations of surface degradation of high‐density polyethylene materials resulting from tracking,using physicochemical analysis

In the present work tracking phenomena were studied with high‐density polyethylene (HDPE) materials under dc voltage, with NH₄Cl and acid rain as contaminants. It was determined that the tracking time of the material depends on the conductivity and flow rate of the contaminant. Furthermore, physicochemical analysis by wide‐angle X‐ray diffraction studies, differential scanning calorimetry, and luminescence spectroscopy was carried out, whereupon it was concluded that the tracking process is a surface‐degradation process. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2843–2849, 2002; DOI 10.1002/app.10260     

飞行器电磁窗耐雨蚀复合涂层的制备

研制了电磁窗用耐雨蚀底漆和耐雨蚀面漆，介绍了该配套涂料体系的制备工艺，并列举了其性能指标。讨论了耐雨蚀面漆中聚酯树脂、多元醇和颜料对其性能的影响，施工工艺对耐雨蚀涂层与底涂层之间配套性能的影响。