Generation of natural daily flow time‐series in regulated rivers using a non‐linear spatial interpolation technique

Daily streamflow time‐series data are often in demand in water resource assessment, water quality and river ecology studies. Such studies normally require daily time‐series representing the natural conditions in a catchment. The generation of these time‐series by means of deterministic physically based daily models is a time consuming approach. This paper describes more pragmatic alternative techniques for generating daily flow sequences using the available observed daily flow records at the neighbouring gauging stations. The daily time‐series representing natural flow conditions at any site of interest may be generated by means of a non‐linear spatial interpolation technique, which is based on 1‐day long‐term flow duration curves for each calendar month of the year. This technique is used to transfer the daily flow information from a source site(s) with data to the destination site where these discharge data are either insufficient or completely missing. The transfer process is based on the assumption that daily flows occurring simultaneously at sites located close to each other correspond to similar probabilities on their respective flow duration curves. Several methods by which to establish the required 1‐day long‐term flow duration curves representing the natural flow regime at the destination site are presented and the conversion of these curves into a complete continuous time‐series of daily discharges is illustrated with the examples from modified streams in South Africa. Copyright © 1999 John Wiley & Sons, Ltd.     

S7-300控制系统在高炉冲渣中的应用

简要介绍了石钢炼铁厂高炉冲渣的工艺过程,并对轮法冲渣控制系统S7-300的硬件配置、软件组成及其实现的功能进行了详细的阐述,认为该系统具有控制精度高、故障点查找方便等优点。     

Measurement and quantification of a sedimentation budget for a reservoir with regular flushing

This paper provides a case study of successful removal of reservoir sediment by empty flushing. The main aim of this study was to determine: (i) sediment inflow to the Cachí reservoir; (ii) the pattern and rate of deposition in the reservoir; (iii) the erosion within the reservoir during flushing; and (iv) sediment outflow at a downstream hydrological station during flushing. The results are integrated as a sediment budget for the reservoir. The drainage basin of the Cachí reservoir in Costa Rica is 785 km². The sediment budget for the period between two flushings indicates a sediment inflow to the reservoir of c. 930 000 tonnes and a net accumulation of c. 133 000 tonnes, or 14.3% of the sediment inflow. The sediment throughflow was also c. 133 000 tonnes up to the erosion phase of the flushing, and the outflow during flushing including bed load was 663 000 tonnes, i.e. 71.4% of the sediment inflow. Thus, the flushing of the reservoir was highly effective in releasing sediment. The balance of the sediment budget makes it probable that the major components of the sediment budget are of the right order of magnitude. The main principle to obtain correct sediment loads by the rating‐curve technique was to collect sediment data from a large number of storm events at equal time intervals during rising and falling stages. This was achieved by turbidimeter recordings. Because of the wide scatter of data, sediment rating curves were developed on mean sediment loads in discharge classes to avoid the bias of log regressions. The trap efficiency and sediment throughflow were determined with Sundborg's physically based sedimentation model. The throughflow amounted to 20% of the suspended sediment inflow, which compares well with the empirical budget. The depositional pattern in the Cachí reservoir was surveyed with side‐scan sonar, repeated echo‐soundings, and by excavating pits in deposits when the reservoir was empty. Deposition occurred mainly in the old river channel, indicating that the major part of the sediment is transported by density currents. The volume of eroded material in the reservoir during scour valve release was estimated by echo‐soundings before and after the flushing. Dry bulk density of the reservoir deposits was determined by X‐ray radiographic and densitometric analysis. The radiographic analyses indicated a dry bulk density of 0.4 g cm⁻³ of the loose material in the thalweg, and 0.7 g cm⁻³ of the whole deposition depth on the terraces. Copyright © 2000 John Wiley & Sons, Ltd.     

基于情感状态转移模型的外界刺激影响分析

为了研究外界刺激时间对人情感状态转移的影响,首先采用Gross情感调节过程和有限状态机描述情感状态转移过程.然后根据外界刺激持续时间的不同,引入了情感增强因子.本文将外界刺激时间与状态转移矩阵进行关联,从而确定不同的刺激时间对情感状态转移的影响.最后对提出的算法进行仿真分析.结果表明,随着外界刺激时间的增加,外界刺激对情感状态转移的影响会越来越大,但是增大的速率会逐渐减慢.该算法可以有效描述外界刺激持续时间与状态转移矩阵的关系.     

连续冲洗式沉沙池截沙率试验研究

对连续冲洗式沉沙池截沙率进行分析研究,并在一维流超饱和输沙法基础上,得出连续冲洗式沉沙池池段分组截沙率、工作段分组截沙率、大于某粒径级截沙率以及总截沙率的近似计算方法。为验证该方法的实用性,对连续冲洗式沉沙池的截沙率进行模型试验,试验结果表明:采用近似处理的截沙率计算公式,其计算结果与实测结果吻合较好,在符合计算精度的前提下,可以用于实际工程计算。     

杂粮蛹虫草菌丝共生体中虫草素的优化提取及测定

目的:探讨杂粮蛹虫草菌丝共生体中虫草素的最优提取条件,并比较了不同光照时长对虫草素含量的影响,为其工艺条件的优化和综合利用提供依据。方法:采用单因素结合响应曲面法优化虫草素的水浴提取条件,高效液相色谱法测定虫草素含量。结果:最优水浴提取条件为:浸提时间6.59 h、浸提温度81.9℃、料液比1∶90,此条件下虫草素含量为6.0143 mg/g;不同光照时长条件下虫草素含量为3.8988~11.9629 mg/g,不同光照时长间差异具有统计学意义(p=0.000)。结论:实验确定了虫草素水浴提取的最优条件,并得出不同光照时长对虫草素含量有显著影响,为进一步优化杂粮蛹虫草菌丝共生体的培养条件提供参考依据。      

基于停留时间的语义行为模式挖掘

移动对象的语义行为模式挖掘是当前移动对象研究中关注的热点,有益于诸多应用场景,如朋友推荐系统、轨迹破案领域和个性化服务等.目前语义行为模式挖掘方法没有考虑移动对象在停留点的停留时间,不能准确地分辨出移动对象之间的不同行为模式.为了解决上述问题,提出了一种基于停留时间的语义行为模式挖掘(discovering common behavior using staying duration on semantic trajectory, DSTra)方法,首先挖掘每个移动对象的频繁语义行为模式,然后定义语义行为模式之间的相似性度量方法,最后采用层次聚类的方法对移动对象进行聚类,找出具有相似行为模式的移动对象群体.实验结果表明：该方法不仅具有合理性和有效性,同时还具有较高的准确率和较好的效率.     

Putrescine Intensifies Glu/GABA Exchange Mechanism and Promotes Early Termination of Seizures

Endogenous anticonvulsant mechanisms represent a reliable and currently underdeveloped strategy against recurrent seizures and may recall novel original therapeutics. Here, we investigated whether the intensification of the astroglial Glu-GABA exchange mechanism by application of the GABA precursor putrescine (PUT) may be effective against convulsive and non-convulsive seizures. We explored the potential of PUT to inhibit spontaneous spike-and-wave discharges (SWDs) in WAG/Rij rats, a genetic model of absence epilepsy. Significant shortening of SWDs in response to intraperitoneally applied PUT has been observed, which could be antagonized by blocking GAT-2/3-mediated astrocytic GABA release with the specific inhibitor SNAP-5114. Direct application of exogenous GABA also reduced SWD duration, suggesting that PUT-triggered astroglial GABA release through GAT-2/3 may be a critical step in limiting seizure duration. PUT application also dose-dependently shortened seizure-like events (SLEs) in the low-[Mg²⁺] in vitro model of temporal lobe epilepsy. SNAP-5114 reversed the antiepileptic effect of PUT in the in vitro model as well, further confirming that PUT reduces seizure duration by triggering glial GABA release. In accordance, we observed that PUT specifically reduces the frequency of excitatory synaptic potentials, suggesting that it specifically acts at excitatory synapses. We also identified that PUT specifically eliminated the tonic depolarization-induced desynchronization of SLEs. Since PUT is an important source of glial GABA and we previously showed significant GABA release, it is suggested that the astroglial Glu-GABA exchange mechanism plays a key role in limiting ictal discharges, potentially opening up novel pathways to control seizure propagation and generalization.     

脱硫GGH结垢离线冲洗效果和冲洗周期选择分析

阐述了三河发电有限责任公司的一期脱硫GGH堵灰的情况,分析了GGH的结构和GGH的积灰、结垢原因,并结合GGH停运离线冲洗的参数、效果和运行采取的措施,认为GGH停运离线冲洗的合理周期为45 d左右。     

直流应力下电极表面覆膜对金属微粒启举的影响机理研究

针对直流GIL中的自由金属微粒污染物问题,研究表面覆膜措施对金属微粒启举的限制机理。利用气体电离及界面电荷积聚理论提出了直流应力下电极覆膜时金属微粒带电及启举模型,并根据微粒带电量的时变特征提出了充电时间的概念。为验证模型的正确性,构建了多功能模块的金属微粒带电.运动观测实验平台,对不同大小、材质的球形金属微粒以及不同厚度的PET薄膜开展实验,实验结果验证了模型的正确性:直流应力下,覆膜措施产生的界面极化过程只是增加了微粒的充电时间,而对微粒最终带电量并无影响,但覆膜产生的静电吸附力可显著提高微粒的启举电压;外施电压、覆膜介电常数及体电导率对微粒充电时间均有显著影响;而由于充电时间的存在使得电极覆膜措施下出现微粒"间歇启举"现象。