江湖流量分配变化导致长江中游新的洪水形势

本文全面论述了江湖流量分配变化导致长江中游出现的新的防洪形势。文中首先举出江湖流量分配的巨大变化。大约在３０年代，四口分流处于鼎盛时期的尾声，尚能分走荆江年径流量约４３１％，洪峰流量约５２７％，以后逐渐衰减，目前（８０年代至９０年代），仅能分走年径流量１５５％，洪峰流量约２９４％。从而使下荆江径流量较３０年代加大约１２３９×１０８ｍ３，洪峰流量加大约１７２００ｍ３／ｓ。可见这种变化是很惊人的。其次全面论述了这种变化对荆江与洞庭湖防洪的影响。仅与５０年代相比，防洪形势有下述变化。第一，荆江特别是下荆江因流量加大抬高的水位大于冲刷（包括裁弯冲刷）降低的水位，从而使洪水位抬高１～２ｍ。第二，莲花塘至武汉因含沙量加大约２５％而淤积，洪水位也有明显的抬高。第三，三口分流河道因径流量减少，加速了衰退与萎缩，淤积比增大，有的河道水环境趋于恶化，严峻的防洪形势并未缓解。第四，洞庭湖泥沙淤积减缓，对保留更多的湖容颇为有利，但湖口城陵矶水位抬高，则对东洞庭湖以至南洞庭湖不利。从总体看，目前这种变化对长江中游是不利的，这种不利突出反映在１９９８年的洪水中。文中在论述这种变化时特别以１９９８年为例予以阐明。

小流量长在线业务对Ev-Do网络的影响及优化

分析了小流量长在线业务对Ev-Do网络的影响,从终端、网络、业务平台3个方面给出专为小流量长在线业务而优化的解决方案,并提出了加强无线运行指标预警及流量疏导等应对策略。

EV-DO网络承载小流量长在线业务的性能分析及优化

分析了小流量长在线业务对EV-DO网络的影响,同时提出了一种业务接入控制的数学模型。通过仿真,得出了DO网络承载小流量长在线业务的网络性能优化方法,该优化方法能提升无线网络性能,接入更多用户。并从终端、网络、业务平台各个环节提出专为小流量长在线业务而优化的解决方案。

Ev-Do网络小流量长在线业务无线优化策略探讨

针对目前Ev-Do网络中小流量长在线业务存在的突出问题,根据呼叫流程,分析了小流量长在线业务对无线资源的占用及资源瓶颈,继而提出了小流量长在线业务的无线优化思路,并进行了相关的案例分析。

磁流变抛光循环系统长时流量稳定性研究

磁流变抛光循环系统的长时流量稳定性,决定着抛光斑参数能否在工件加工周期内保持稳定,是实现确定性抛光的重要保证。从循环系统用离心泵入手,建立流量稳定性评价方法,设计了三种离心泵模型;采用数值分析方法,对其输出流量稳定性进行了比较分析,并通过循环系统流量稳定性实验对分析结果进行了验证。结果表明:提出的离心泵流量稳定性评价方法切实可行,由锥形压水室结构和双面叶轮所构成的离心泵模型流量稳定性最好,基于其构建的磁流变抛光循环系统相对另外两种离心泵模型构建的磁流变抛光循环系统具有最好的长时流量稳定性。

多洞多机长引水大流量水电工程能量指标优化计算研究

针对目前多洞多机长引水大流量水电工程特点,及其在设计过程中能量指标计算存在的不足,建立了优化计算模型和算法,并通过编程实现程序化。通过实例分析,优化成果更符合电站运行特性,计算成果合理,模型可行,可用于工程设计过程中的洞机方案比选,也可为电站实际运行过程的优化调度提供决策参考。

海上超长水平段MRC井钻完井关键技术研究与应用

对于高含水、低渗透、非常规超薄致密性碳酸盐油气藏以及浅海油田和新能源开发项目,MRC井是一项具有针对性的创新技术,通过最大化储层接触面积,并配合一系列配套钻完井工艺,能有效提高单井产量并降低桶油成本。随着MRC技术在阿布扎比海上项目的投入使用,与MRC井配套的钻井技术和完井技术也在飞速发展。超薄低渗致密性碳酸盐储层MRC井眼轨迹精确控制技术、超长MRC井一趟钻优快高效钻井技术等钻井相关的关键技术,以及MRC长水平段均衡流量控制技术、MRC井高效储层改造酸化技术等完井相关的关键技术被成功应用在阿布扎比海上项目。截至2020年,共计9口MRC井在阿布扎比海上项目投产作业,其平均产量约是常规水平井的2.5倍,每口井大概节约成本1200万美元。MRC井技术在最大化单井产能、实现高效的项目资本支出上取得显著成果。

长腰内锥流量计的特性研究

内锥式流量计在多相流测量中的应用逐渐受到广大多相流研究工作者的重视。针对内锥式流量计在多相流测量中存在的一些问题,提出一种新型的环形通道式差压流量计—长腰内锥流量计。通过理论推导得出流量方程及永久压损与流量的关系式,并通过在水相、油相、气相条件下的标定实验,定量分析流出系数与永久压损等特性。结果表明:在长腰内锥体腰部取低压可以在保证差压信号幅值的情况下提高其稳定性、重复性;长腰内锥流量计节流件的轮廓及固定方式可以显著地减小永久压损。为后期开发新型多相流测量仪器提供理论依据与设计基础。

Hybrid evolutionary algorithm for no-wait flow shops to minimize makespan and total flowtime

The NP-hard no-wait flow shop scheduling problems with makespan and total flowtime minimization are considered. Objective increment properties of the problems are analyzed. A non-dominated classification method is introduced to class population individuals into Pareto fronts to improve searching efficiency. Besides investigating the crowding distance and the elitist solution strategy, two effective bi-criteria local search procedures based on objective increments are presented to improve searching effectiveness. Based on the properties and methods, a hybrid evolutionary algorithm is proposed for the considered problems and compared with the best existing algorithms. Experimental results show that the proposed algorithm is effective with high efficiency.

Streamflow and Soil Moisture of Agroforestry and Grass Watersheds in Hilly Area

A study was conducted in a hilly area of Sichuan Province,Southwestern China, to compare the streamflow and soil moisture in two upland watersheds with different land use patterns. One was an agroforestry watershed, which consisted mainly of trees with alder (Alnus cremastogyne Burkill) and cypress (Cupressus funebris Endl.) planted in belts or strips with a coverage of about 46%, and the other was a grassland primarily composed of lalang grass (Imperata cylindrica var. major (Nees) C. E. Hubb.), filamentary clematis (Clematis filamentosa Dunn) and common eulaliopsis (Eulaliopsis binata (Retz.) C. E. Hubb) with a coverage of about 44%. Streamflow measurement with a hydrograph established at the watershed outlet showed that the average annual streamflow per 100 mm rainfall from 1983 to 1992 was 0.36 and 1.08 L s-1 km-2 for the agroforestry watershed and the grass watershed, respectively. This showed that the streamflow of the agroforestry watershed was reduced by 67% when compared to that of the grass watershed. The peak average monthly streamflow in the agroforestry watershed was over 5 times lower than that of the grass watershed and lagged by one month. In addition, the peak streamflow during a typical rainfall event of 38.3 mm in August 1986 was 37% lower in the agroforestry watershed than in the grass watershed. Results of the moisture contents of the soil samples from 3 slope locations (upper, middle and lower slopes) indicated that the agroforestry watershed maintained generally higher soil moisture contents than the grass watershed within 0-20 and 20-80 cm soil depths for the upper slope, especially for the period from May through July. For the other (middle and lower) slopes, soil moisture contents within 20-80 cm depth in the agroforestry watershed was generally lower than those in the grass watershed, particularly in September, revealing that water consumption by trees took place mainly below the plow layer. Therefore, agroforestry land use types might offer a complimentary model for tree-annual crop water utilization.

中国电信3G网络典型数据业务优化

为了提升对3G网络典型数据业务的支持能力以及用户对网络典型业务的感知程度,文章分别研究了中国电信3G网络的两类典型数据业务(小流量长在线业务与反向视频上传业务),并给出相应的优化方法。该业务优化方法与3G网络基础优化方法结合,可进一步提升3G网络数据业务性能。

A Spatial Cluster Analysis of Heavy Rains in China

Clustered heavy rains （CHRs） defined using hierarchical cluster analysis based on daily observations of precipitation in China during 1960-2008 are investi- gated in this paper. The geographical pattern of CHRs in China shows three high-frequency centers--South China, the Yangtze River basin, and part of North China around the Bohai Sea. CHRs occur most frequently in South China with a mean annual frequency of 6.8 （a total of 334 times during 1960-2008）. June has the highest monthly frequency （2.2 times/month with a total of 108 times dur- ing 1960-2008）, partly in association with the Meiyu phenomenon in the Yangtze River basin. Within the past 50 years, the frequency of CHRs in China has increased significantly from 13.5 to 17.3 times per year, which is approximately 28%. In the 1990s, the frequency of CHRs often reached 19.1 times per year. The geographical extent of CHR has expanded slightly by 0.5 stations, and its average daily rainfall intensity has increased by 3.7 mm d-1. The contribution of CHRs to total rainfall amount and the frequency of daily precipitation have increased by 63.1% and 22.7%, respectively, partly due to a significant decrease in light rains. In drying regions of North and Northeast China, the amounts of minimal CHRs have had no significant trend in recent years, probably due to warming in these arid regions enhancing atmospheric conveetivity at individual stations.

新生儿呼吸机与通用呼吸机的区别

新生儿的胸,肺,心,不同于儿童与成人。所以呼吸机技术参数要求(潮气量,压力,容量,流速)……不同于通用呼吸机。前者是以量程小而精为优。机械结构的阀门,管道,加温湿化器,传感器……也不同于通用机。本文详尽的介绍了二者的区别和产品的对策。

Scale-Free Properties in Traffic System

In this work, we propose a new model of evolution networks, which is based on the evolution of the traffic flow. In our method, the network growth does not take into account preferential attachment, and the attachment of new node is independent of the degree of nodes. Our aim is that employing the theory of evolution network, we give a further understanding about the dynamical evolution of the traffic flow. We investigate the probability distributions and scaling properties of the proposed model The simulation results indicate that in the proposed model, the distribution of the output connections can be well described by scale-free distribution. Moreover, the distribution of the connections is largely related to the traffic flow states, such as the exponential distribution （i.e., the scale-free distribution） and random distribution etc.

Filling of the Three Gorges Reservoir to the 135-m Level: Instant Effects on the Yangtze Discharge and Suspended Sediment Concentration Entering the Estuary

Via the valuable opportunity of the Three Gorges Reservoir (TGR) 135-m filling in June 2003, the Yangtze discharge and suspended sediment concentration (SSC) entering the estuary during the period from 15 May to 15 July 2003 were analyzed to examine the instant effects of the filling on them. The Yangtze discharge and SSC entering the estuary in the periods before, during and after the filling clearly indicated three phases: 1) the pre-storage phase characterized by natural conditions, in which the SSC increased with increasing water discharge; 2) the storage phase, during which the SSC decreased dramatically with decreasing water discharge; and 3) the post-storage phase, during which both the SSC and water discharge remained at relatively low levels first until the end of June, then the SSC increased gradually with increasing water discharge. It seems that the times for the instant effects of the decreasing discharge downstream from the upper Yangtze on the Yangtze discharge and SSC entering the estuary due to the TGR 135-m filling to take place were about 5 d and 1 d respectively, while both were about 18 d for those of the increasing discharge. This probably reflects the buffering and resultantly hysteresis of the 1800-km stretch from the upper Yangtze to the estuary. The results are helpful for scientific and hydrological investigation of the Yangtze mainstream downstream from the TGR Dam and of the estuarine and adjacent coastal waters.

Evaluation of line brattice length in an empty heading to improve air flow rate at the face using CFD

The effectiveness of line brattice(LB) ventilation system depends on the associated system variables.However, the effect of these variables on the air flow rates close to the face of the heading is not extensively studied. In this paper, the effect of the LB length in relation to the LB-wall distance on the air flow rate reaching the face is analysed. Scenarios were developed using four LB lengths, two LB-wall distances and two heading depths. These scenarios were simulated with a validated CFD model. The air flow rates and patterns at various locations inside the heading were analysed. This helped to find the minimum LB-face distance that should be maintained for each LB-wall distance to maximise the air flow rate at the face. The minimum length when used will improve ventilation and reduce energy cost.

Century-long variability and trends in daily precipitation characteristics at three Finnish stations

Long-term variations and trends in a wide range of statistics for daily precipitation characteristics in terms of intensity, frequency and duration in Finland were analysed using precipitation records during 1908e2008 from 3 meteorological stations in the south(Kaisaniemi),centre(Kajaani) and north(Sodankyl€a). Although precipitation days in northern part were more frequent than in central and southern parts, daily precipitation intensity in the south was generally higher than those in the centre and north of the country. Annual sum of very light precipitation(0 mm < daily precipitation long-term 50 th percentile of daily precipitation more than 0 mm) significantly( p < 0.05) decreased over time,with the highest rate in northern Finland. These decreasing trends might be the result of significant increases in frequency of days with very light precipitation at all the stations, with the highest and lowest rates in northern and southern Finland, respectively. Ratio of annual total precipitation to number of precipitation days also declined in Finland over 1908e2008, with a decreasing north to south gradient. However, annual duration indices of daily precipitation revealed no statistically significant trends at any station. Daily precipitation characteristics showed significant relationships with various well-known atmospheric circulation patterns(ACPs). In particular, the East Atlantic/West Russia(EA/WR)pattern in summer was the most influential ACP negatively associated with different daily precipitation intensity, frequency and duration indices at all three stations studied.

Wavelength Routing Algorithmof All Optical Network Based on Traffic Engineering

General multi-protocol label switching(GMPLS) based on traffic engineering is one of the possible methods to implement all-optical network. This method implements the network with IP technique and guarantees the quality of service with traffic engineering. Based on the establishment of selecting schemes of optical path and methods of traffic calculation, the wavelength routing algorithm of all-optical network based on traffic engineering is presented by combining with prior route of shortest path and traffic engineering, the algorithm procedures are given, and the actual examples are introduced as well as the analysis on simulation calculation. This research results have certain significance for the achievement of optical switching technique of all-optical network.

The Energy Growth Property for Harmonic Maps

In this paper,we study the energy growth property for a class of harmonic maps. A special estimation of energy growth is obtained.

Seasonal variation of tidal prism and energy in the Changjiang River estuary： a numerical study

Tidal rivers are intrinsically complex because tidal propagation is influenced by river discharge. This study aims to examine the seasonal variation of tidal prism and energy variance in the tidal river of the Changjiang(Yangtze) River estuary in China. In order to quantify the behaviour of river and tide,we use numerical modelling that has been validated using measured data. We conduct our analysis by quantifying the discharge and energy variance in separate components for both the river and the tide,during wet and dry seasons. We note various definitions of tidal prism and explore the difference between tidal discharge on the flood and ebb and tidal storage volume. The results show that the river discharge attenuates the tidal motion and reduces the tidal flood discharge but the tidal storage volume is approximately constant with different riverine discharge since part of the fresh water discharge is intercepted and captured in the estuary due to the backwater effect. It appears that the tidal discharge adjusts according to the variation of river discharge to keep a constant tidal storage volume. An analysis of the hydraulics shows that the transition from tidal dominance(at the mouth) to river dominance(upstream) depends on the location of tidal current reversal which varies from wet season to dry season. Duringthe wet season,the Changjiang River estuary is totally dominated by energy from fresh water discharge.