波流式生态滤床氨氮去除效果及其微生物群落结构分析

利用波流式生态滤床处理受污染的河水,考察了其对氨氮的去除效果和沿程污染物转化情况,并采用扫描电镜、高通量测序手段解析了波流式生态滤床不同时间和位置基质上生物膜的细菌群落组成,分析了波流式生态滤床小试反应器中硝化细菌和反硝化细菌的分布特点,以探讨其去除氨氮的机理.结果表明,反应器稳定运行以后,对氨氮平均去除率为74.83%,基质表面可以观察到大量微生物,不同时期优势细菌有较大不同.反应器前部主要发挥硝化作用,中部发挥反硝化作用,硝化菌的分布呈现上多下少、前多后少的特点,使得氨氮在前端被快速去除;中部以黄杆菌属(Flavobacterium)为代表的反硝化菌丰度较高,促进了反硝化作用的发挥,降低了出水中总氮浓度;不同部位样品中细菌多样性差别不大,微生物种群多样性随着水流方向呈现先增加,到后段减少的趋势.

坐底式波流测量仪

本文简述坐底式波流测量仪计算海流和波浪反演的原理 ,并详细介绍了水槽率定及海上试验情况和结果。

水流动能开发新技术——介绍桁架式柔性叶片横轴转子

分析了我国水流动能资源和利用现状,推荐了一种新型桁架式水流动能利用转子,指出了这种转子在开发利用江河水流动能、潮汐能、波浪能几种水流动能形式中的技术特色和优势,探讨了它与现有常规水能利用技术形式的区别,并对我国水流动能利用的发展前景提出了看法。

HYBRID SCHEME FOR COMPRESSIBLE TURBULENT FLOW AROUND CURVED SURFACE BODY

A hybrid central-upwind scheme is proposed. Two sub-schemes, the central difference scheme and the Roets flux difference splitting scheme, are hybridized by means of a binary sensor function. In order to examine the capability of the proposed hybrid scheme in computing compressible turbulent flow around a curved surface body, especially the flow involving shock wave, three typical eases are investigated by using detached-eddy simulation technique. Numerical results show good agreements with the experimental measurements. The present hybrid scheme can be applied to simulating the compressible flow around a curved surface body involving shock wave and turbulence.

Experimental Research on Gas-Liquid Two-Phase Spiral Flow in Horizontal Pipe

In view of the importance of gas-liquid two-phase spiral flow and the few research reports at home and abroad,the gas-liquid two-phase spiral flow patterns have been researched in a horizontal pipe with different parameters investigated by means of observation and a high-speed camera.Since the appearance of spiral flow makes the distribution of twophase flow more complicated,the flow patterns appearing in the experiments were divided into the Spiral Wavy Stratified Flow(SWS),the Spiral Bubble Flow(SB),the Spiral Slug Flow(SS),the Spiral Linear Flow(SL),the Spiral Axial Flow(SA),and the Spiral Dispersed Flow(SD) by the observations and with reference to the predecessors' research achievements.A flow pattern map has been drawn up.The influence of velocity,vane angle and vane area on flow pattern conversion boundary and pressure drop has been studied,with a solid foundation laid for the future research work.

Wave propagation of the traffic flow dynamic model based on wavefront expansion

This paper discusses propagation of perturbations along traffic flow modeled by a modified second-order macroscopic model through the wavefront expansion technique. The coefficients in this expansion satisfy a sequence of transport equations that can be solved analytically. One of these analytic solutions yields information about wavefront shock. Numerical simulations based on a Padé approximation of this expansion were done at the end of this paper and results showed that propagation of perturbations at traffic flow speed conforms to the theoretical analysis results.

A Synoptic Snapshot of the East Cape Eddy(ECE)

A synoptic snapshot in this study is made for the East Cape Eddy (ECE) basedon the World Ocean Circulation Experiment (WOCE) P14C Hydrographic Section and Shipboard ADCPvelocity vector data collected in September 1992. The ECE is an anticyclonic eddy, barotropicallystructured and centered at 33.64°S and 176.21°E, with warm and salinous-cored subsurface water.The radius of the eddy is of the order O (110 km) and the maximum circumferential velocity is O (40cm s^(-1)); as a result, the relative vorticity is estimated to be O (7 x 10^(-6)s^(-1)). Due to theexistence of the ECE, the mixed layer north of New Zealand becomes deeper, reaching a depth of 300m in the austral winter. The ECE plays an important role in the formation and distribution of theSubtropical Mode Water (STMW) over a considerable area in the South Pacific.

DESIGN OF MULTIPLE-LOOP FEEDBACK HIGH-ORDER CURRENT-MODE FILTER BASED ON FTFNS

A general multiple-loop feedback approach for realization of Four-Terminal Floating Nullor RC(FTFN-RC) filter is presented.The proposed filter is constructed by multi-output FTFNs, capacitors and resistors.It can simultaneously realize slow-pass, band-pass(if order is even number), and high-pass filter responses.With RC elements grounded and requiring no component matching con-straints, it is fully integrated conveniently.Simulations are performed for the fourth-order Butterworth filter to verify the validity of the circuit.

Air-sea fluxes of heat and momentum over the Yellow Sea during cold air outbreaks

The impact of sea surface waves on air-sea fluxes of heat and momentum over the Yellow Sea caused by cold fronts during cold air outbreak(CAO)events is investigated through numerical experiments with a FVCOM-SWAVE(Finite-Volume Coastal Ocean Model-Surface WAVE)wave-current coupled model.Two typical types of cold fronts,i.e.,those respectively from the north and from the west,are simulated and compared to each other and with monthly mean.During cold seasons,currents in the Yellow Sea are weaker than that during warm seasons.As a result,waves show a more prominent impact.The numerical simulations suggested that both the heat and momentum fluxes are significantly enhanced during CAO events;and they could be a few times larger than the monthly average of a five-year mean.The enhancement is highly sensitive to the features of CAOs.Specifically,it depends on the cold front orientation,intensity and evolution.One mechanism that strengthens the two fluxes is via sea waves.For the CAOs that are studied,an increase in sea wave height by 50%can double the maximal momentum flux,and cause an increase in heat flux by 10-160 W/m^2.

The urban unsteady and non-pressure rain pipe flow routing by the dynamical-wave method

The dynamical-wave routing model of the urban unsteady and non-pressure rain pipe flow was established by conservation of mass, momentum and energy, and it was solved by applying the four point implicit difference method and the pursuit method. It was obtained from the experiment checking and comparative analysis that the dynamical-wave muting model can reflect influence like attenuate and backwater when flood peak propagate in pipeline with high calculation precision and vast application scope, and it can be applied in routing of urban rain pipe flow of different slopes and inflow conditions. The routing model supplies a scientific foundation for the town rainfall piping design or checking, disaster administration of storm runoff, and so on.

Flow around Wells Type Runner Installed in Floating Type Unique Ocean Wave Power Station

The authors have proposed the unique ocean wave power station, which is composed of the floating type platform with a pair of floats lining up at the interval of one wave pitch and the power unit where the runners are submerged at the middle of the platform. Such a profile can make the flow velocity at the runner twice faster than that of OWC （oscillating water column） type constructed adjacent to the seashore. The behavior of the platform in the wave has been reported, and this paper continuously investigates the effects of the runner casing on the runner work and the platform behavior. Besides, the flows around the Wells type, not only single runner but also tandem runners are investigated numerically. It was confirmed that the runner work attenuates the platform amplitude and the runner casing contributes to increase the output. The flow simulation suggests that the tandem runners may be appropriate for the floating type ocean wave power station to get enough output.

Constant Ripple Current Control for Switching DC-DC Converter

The adapted DC-DC converters should be smaller in size and have a small output current ripple to meet the increasing demand for low voltages with high performance and high density micro processors for several microelectronic load applications. This paper proposes a DC-DC converter using variable on-time and variable switching frequency control enhanced constant ripple current control and reduced magnetic components. The proposed converter is realized by making the turn-offtime proportional to the on-time of the converter, according to the input and output voltage, thereby reducing the corresponding current ripple on output voltage in the continuous conduction mode. A Buck DC-DC converter using the proposed control strategy is analyzed in detail, along with some experimental results to show the performance and effectiveness of this converter.

A Theoretical Dynamic Analysis of a Regenerative Heat Exchanger Assembly in a Fluctuating Flow Regime

A fluctuating flow was used to investigate the thermo-fluid characteristic of a regenerative heat exchanger assembly designed, modelled, built and constructed for the used in Stifling engines applications. Vibration of the regenerative heat exchanger assembly was a problem to deal with during the experimental investigation. Hence, a dynamic analysis of the regenerative heat exchanger assembly was undertaken. The main sources of excitation in vibrations of the regenerative heat exchanger assembly were investigated and calculated based initially on the empirical correlations provided in the literature. Thereafter, a mathematical model of the regenerative heat exchanger assembly was developed based on the energy equations for each moving part of the assembly. The kinetic and potential energy equations were formulated for each moving part of the regenerative heat exchanger assembly. From the kinetic and potential equations, the Lag, range operator was defined, and then the Lagrange formulations were used to derive the differential equations representing the dynamic behavior of each moving part of the assembly. The differential equations were integrated to determine the system natural frequencies. These were then compared to the frequency on excitation in vibrations in order to predict the regenerative heat exchanger working conditions despite the existence of vibration in the system.

Low power density microwave radiation induced early changes in rabbit lens epithelial cells

Objective To determine whether low power density microwave radiation can induce irreversible changes in rabbit lens epithelial cells (LECs) and the mechanisms of the changes.Methods One eye of each rabbit was exposed to 5mW/cm2 or 10mW/cm2 power density microwaves for 3 hours, while the contralateral eye served as a control. Annexin Ⅴ-propidium iodide (PI) two-color flow cytometry (FCM) was used to detect the early changes in rabbit lens epithelial cells after radiation. Results Lots of rabbit LECs were in the initial phase of apoptosis in the 5mW/cm2 microwave radiation group. A large number of cells became secondary necrotic cells, and severe damage could be found in the group exposed to 10mW/cm2 microwave radiation. Conclusion Low power densities of microwave radiation (5mW/cm2 and 10mW/cm2) can induce irreversible damage to rabbit LECs. This may be the non-thermal effect of microwave radiation.

Two kinds of peaked solitary waves of the KdV,BBM and Boussinesq equations

It is well-known that the celebrated Camassa-Holm equation has the peaked solitary waves,which have been not reported for other mainstream models of shallow water waves.In this letter,the closed-form solutions of peaked solitary waves of the KdV equation,the BBM equation and the Boussinesq equation are given for the first time.All of them have either a peakon or an anti-peakon.Each of them exactly satisfies the corresponding Rankine-Hogoniot jump condition and could be understood as weak solution.Therefore,the peaked solitary waves might be common for most of shallow water wave models,no matter whether or not they are integrable and/or admit breaking-wave solutions.