小流量电磁流量计在三元配注工艺中的应用

本文针对现场三元注入泵没有流量计量装置,注入量调整难度大的问题,开展了国产小流量电磁流量计试验。

电磁流量计与漩涡流量计的原理及应用

工业生产中工艺参数的采集根据被测变量的不同一般分为温度、压力、流量、物位和分析仪表。本文就流量的测量进行分析。

流程工业用小流量超声流量计

简述流程工业用超声流量计不能用于小管径和低流速测量的原因,列举了小流量超声流量计的流量传感器结构上改进和代表性气体和液体的性能。

热真空条件下工作的电气电缆载流量计算与试验

高空制导飞行器从母舱释放后,制导舱与仪器舱之间部分电气电缆处于热真空条件下工作。对此种特定条件下的电缆进行了载流量计算。理论计算表明,给定的电缆设计满足在热真空条件下正常工作要求。最后简略介绍了载流量试验。

煤气流量检测技术及其应用

选择合适的流量检测技术，是实现煤气流量准确检测的关键。本文简要介绍了常用煤气流量检测技术的原理及其特点，并结合棒材厂在实际中的应用，总结出一套煤气流量检测的成功经验。

基于恒磁励磁传感技术的水流量测量干扰的分析

文章描述了采用恒磁励磁传感技术的水流量测量传感器在电子水表或流量计应用中存在的极化干扰电势影响等问题,分析了产生干扰的原因和机理,提出了解决极化干扰电势的几种主要方法和技术。文章的结论是恒磁励磁传感技术在水流量计量仪表方面的应用会随着技术进步而逐步扩大,其性能会逐步改善。

试谈实时压力补偿在Micro Motion质量流量计流量与密度测量中的实现

本文介绍了在Micro Motion质量流量计流量与密度测量中压力补偿的情况,对采用1700/2700型变送器流量和密度测量进行实时压力补偿的情况进行分析。

Application of Hilbert-Huang transform to denoising in vortex flowmeter

Due to piping vibration, fluid pulsation and other environmental disturbances, variations of amplitude and frequency to the raw signals of vortex flowmeter are imposed. It is difficult to extract vortex frequencies which indicate volumetric flowrate from noisy data, especially at low flowrates. Hilbert-Huang transform was adopted to estimate vortex frequency. The noisy raw signal was decomposed into different intrinsic modes by empirical mode decomposition, the time-frequency characteristics of each mode were analyzed, and the vortex frequency was obtained by calculating partial mode’s instantaneous frequency. Experimental results show that the proposed method can estimate the vortex frequency with less than 2% relative error; and in the low flowrate range studied, the denoising ability of Hilbert-Huang transform is markedly better than Fourier based algorithms. These findings reveal that this method is accurate for vortex signal processing and at the same time has strong anti-disturbance ability.

浅析影响煤焦中硫含量测定精确度的因素

简述煤焦中硫含量测定的方法原理及操作步骤,从试样量、流量计流量、电解液体积等方面讨论测定煤焦硫含量的影响因素,通过实验对比以寻求保证硫含量精确度的最佳方法,即通过实验确定试样量约50mg左右、流量计流量一般保持在1 000mL/min,并需定期清洗电解池及电极片、及时更换变色硅胶及电解液。

Left Ventricle Failure and Blood Flow Estimation for Centrifugal Blood Pumps

This paper shows the blood flow control （FwC） performance to adjust rotational speed of an ICBP （implantable centrifugal blood pump） in order to provide an adequate flow to left ventricle in different patient conditions. ICBP is a totally implantable LVAD （left ventricular assist device） with ceramic bearings developed for long term circulatory assistance. FwC uses PI （proportional-integral） control to adjust rotational speed in order to provide blood flow. FwC does not use sensor for feedback, as there is an estimation system to provide blood flow measurement. Control strategy has being studied in a HCS （hybrid cardiovascular simulator） as a tool that allows the physical connection of ICBP during evaluation. In addition, HCS allows changes of some cardiovascular parameters in order to simulate specific heart disease： ejection fraction （10-25%） and heart rate （50-110 bpm）. FwC was able to adjust blood flow with steady error less than 2%. Results demonstrated that FwC is adequate to LVAD control irL different left ventricle failure conditions.

Measurment of gas-liquid two-phase slug flow with a Venturi meter based on blind source separation

We propose a novel flow measurement method for gas–liquid two-phase slug flow by using the blind source separation technique. The flow measurement model is established based on the fluctuation characteristics of differential pressure(DP) signals measured from a Venturi meter. It is demonstrated that DP signals of two-phase flow are a linear mixture of DP signals of single phase fluids. The measurement model is a combination of throttle relationship and blind source separation model. In addition, we estimate the mixture matrix using the independent component analysis(ICA) technique. The mixture matrix could be described using the variances of two DP signals acquired from two Venturi meters. The validity of the proposed model was tested in the gas–liquid twophase flow loop facility. Experimental results showed that for most slug flow the relative error is within 10%.We also find that the mixture matrix is beneficial to investigate the flow mechanism of gas–liquid two-phase flow.

Real-time Capturing and Measurement of Traffic Flow Based on WinPcap

In order to understand how a network is being used or whether it is being abused, an administrator needs to inspect the flow of the traffic and ＂infers＂ the intent of the users and applications. So the network traffic measurement and analysis are crucial to network monitoring, reliable DDoS detecting and attack source locating as well. In this paper, we discuss the principle of real-time network traffic measurement and analysis through embedding a traffic measurement and analysis engine into IP packet-decoding module, and emphasize the implementation of visualizing the real-time network traffic, which are helpful to network monitoring and network traffic modeling.

Design and Implementation of Computer Network Traffic Monitoring

This paper focuses on the key technologies of P2P and network traffic monitoring, research and analyze the traditional P2P flow control technology and the working principle of deployment, discuss on the straight loss and bypass interference control technology, and the reasonable combination of two kinds of technology to design straight bypass joint deployment. On basis of it, we design a new P2P traffic monitoring system. Through the design and implementation of computer network traffic monitoring system based on C/S mode to achieve automatic control, maintenance, and monitor network traffic, which is suitable for the current engineering software to monitor a network application environment. From the network users and network operator＇ s perspective, monitoring of network traffic is scientific, reasonable that improve network management and it has important research value.

Calculation of stratosphere–troposphere exchange in East Asia cut-off lows:cases from the Lagrangian perspective

In this study,the authors focus on the cut-off low pressure systems（COLs）lingering over East Asia in late spring and early summer and quantify the two-way stratosphere–troposphere exchange（STE）by 3D trajectory integrations,achieved using a revised version of the UK Universities Global Atmospheric Modelling Programme Offline Trajectory Code（Version 3）.By selecting 10 typical COLs and calculating the cross-tropopause air mass fluxes,it is found that stratosphere-to-troposphere transport（STT）fluxes exist in the center of COLs;and in the periphery of the COL center,troposphereto-stratosphere transport（TST）fluxes and STT fluxes are distributed alternately.Net transport fluxes in COLs are from stratosphere to troposphere,and the magnitude is about 10-4 kg m-2 s-1.The ratio between the area-averaged STT and TST fluxes increases with increasing strength of the COLs.By adopting appropriate residence time,the spurious transports are effectively excluded.Finally,the authors compare the results with previous studies,and find that the cross-tropopause fluxes（CTFs）induced by COLs are about one to two orders of magnitude larger than global CTFs.COLs play a significant role in local,rapid air mass exchanges,although they may only be responsible for a fraction of the total STE.

Disclosure Quality in Goodwill Impairment Tests： Turkey Case

The issue of goodwill impairment has been debated in many countries throughout the world. Adoption of International Financial Reporting Standards （IFRS） introduced fundamental changes in accounting and impairment methods for goodwill. Since global stock markets went into decline in 2008, there has been much debate over the issue of goodwill impairment in the US and European stock exchange markets, especially on how large the write-downs should be. Complexity of International Accounting Standards （IAS） and IFRS focusing on goodwill and goodwill impairment techniques may lead to inconsistent compliance and varying levels of disclosure quality. The aim of this study is to analyze goodwill impairment during and after the recent financial crisis for companies listed on the Borsa Istanbul （BIST） 100 index and to assist the financial statement users in the assessment of disclosure quality under IAS 36, Paragraph 134d. Tools such as： （1） the period over which management has projected cash flows; （2） the growth rate used for cash flow projections; （3） the discount rate（s） applied to projections; and （4） methods employed to determine recoverable amount are analyzed. Insufficient disclosures on these tools are observed. The findings are of interest to researchers examining the implication of IAS 36, regulators, and policy-setters.

Performance Test and Flow Measurement of Contra-Rotating Axial Flow Pump

An application of contra-rotating rotors has been proposed against a demand for developing higher specific speed axial flow pump. In the present paper, the advantage and disadvantage of using contra-rotating rotors are described in comparison with conventional type of rotor-stator, based on theoretical and experimental investigations. The advantages are as follows： （1） The pump is inherently designed as smaller sized and at lower rotational speed. （2） A stable head-characteristic curve for flow rate with negative slope appears. （3） As the rear rotor rotational speed is varied as independent control of front rotor, the wider range of high performance operation is obtained by rear rotor speed control in addition to front rotor speed control. The disadvantages are as follows： （1） The structure of double shaft system becomes complex. （2） The pump performance is inferior at over flow rate as the rear rotor loading is weakened. （3） The blade rows interaction from rear rotor to front rotor more strongly appears. Then the rear rotor design is a key to achieve higher pump performance. Some methods to overcome these disadvantages will be discussed in more details toward wider usage of contra-rotating axial flow pump in various industrial fields.

Influences of cavity leakage on the design of low flow coefficient centrifugal impeller

The low flow coefficient centrifugal impeller(LFCCI)gives a relatively low efficiency and a special treatment is required for the design of this kind of impeller.This paper investigates the influences of cavity leakage on the performance prediction and design of LFCCI based on Computational Fluid Dynamics(CFD)techniques.The results show that,the reduction in the effi-ciency of impeller due to the introduction of cavity leakage varies with the blade shape of impeller in a wide range since there is a strong and complex interaction of main flow and leakage flow in the LFCCI.To get a credible optimization result,the backside and foreside cavities should be considered in the CFD-based design of LFCCI.

The Effect of Diffuser Angle on the Discharge Coefficient of a Miniature Critical Nozzle

Many researches on critical nozzles have been performed to accurately measure the mass flow rate of gas flow,and to standardize the performance as a flow meter.Recently,much interest is being paid on the measurement of very small mass flow rate in industry fields such as MEMS applications.However,the design and performance data of the critical nozzles obtained so far have been applied mainly to the critical nozzles with comparatively large diameters,and the works available on miniature critical nozzles are lacking.In the present study,a computational fluid dynamics method has been applied to investigate the influence of the diffuser angle on discharge coefficient of the miniature critical nozzles.In computations,the throat diameter of critical nozzle is varied from 0.2 mm to 5.0 mm and the diffuser angle is changed from 2 deg to 8 deg.The computational results are validated with some experimental data available.The results show that the present computational results predict appropriately the discharge coefficient of the gas flows through miniature critical nozzles.It is known that the discharge coefficient is considerably influenced by the diffuser angle,as the throat diameter of nozzle becomes small below a certain value.This implies that the miniature critical nozzles should be carefully designed.

Study of Choked Flows through a Convergent Nozzle

When sonic nozzles of significantly smaller diameter are used as standard flow meters,the critical back pressure ratio is affected by the boundary layer at the nozzle throat.However,the effect of the boundary layer on choking criteria is still controversial.Then,the choking phenomenon of a convergent nozzle flow has been experimentally investigated using four convergent nozzles with the same diameter followed by a straight pipe of a variable length.As a result,it is shown that the critical back pressure ratio is smaller than that for the steady one-dimensional is-entropic flow and decreases as the boundary layer thickness increases.Moreover,the main flow Mach number at the nozzle exit is supersonic when the back pressure ratio is equivalent to the choking condition,and the Mach number increases as the boundary layer thickness increases.