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1.
Li C  Zhang YP  Guo WD  Zhu Y  Xu J  Deng X 《光谱学与光谱分析》2010,30(9):2541-2545
通过对2007年10月-2008年4月经停厦门港的不同航线9条国际船舶29个压舱水中有色溶解有机物(CDOM)的三维荧光光谱和吸收光谱分析,探讨了利用CDOM光谱参数检验进出我国港口的国际船舶是否进行了远洋压舱水交换(BWE)国际公约规定的可行性.利用平行因子分析(PARAFAC)对三维荧光光谱进行解潜,共鉴别出压舱水CDOM具有2个类腐殖质及2个类蛋白质荧光组分,其中长波类腐殖质组分C2(250,345/458 nm)可作为判断压舱水是否进行BWE的合适指标.压载舱中各荧光组分垂直分布基本均匀.利用C2组分结合吸收光谱斜率比值SR、盐度等指标.对七述船舶是否进行BWE作出了准确判断.研究结果表明,3类指标的综合应用将能更有效地对国际船舶是否进行BWE进行可靠的检验,对今后在厦门港乃至国内其他港口开展压舱水水源的快速检测提供了技术支撑.  相似文献   

2.
丁欣 《物理学报》2008,57(1):211-216
This paper reports a continuous-wave (CW) mid-infrared intracavity singly resonant optical parametric oscillator based on periodically poled lithium niobate (PPLN) pumped by a diode-end-pumped CW Nd:YVO$_{4}$ laser. Considering the thermal lens effects, it adopted an optical ballast lens and the near-concentric cavity for better operation. At the PPLN's grating period of 28.5\,$\mu$m and the temperature of 140\du, the maximum idler output power of 155\,mW at 3.86\,$\mu$m has been achieved when the 808\,nm pump power is 8.5\,W, leading to an optical-to-optical conversion efficiency of 1.82{\%}.  相似文献   

3.
丁欣  盛泉  陈娜  禹宣伊  王睿  张衡  温午麒  王鹏  姚建铨 《中国物理 B》2009,18(10):4314-4318
In this paper we report on a continuous-wave (CW) intracavity singly resonant optical parametric oscillator (ICSRO) based on periodically poled LiNbO3 (PPLN) pumped by a diode-end-pumped CW Nd:YVO4 laser. Considering the thermal lens effects and diffraction loss, an optical ballast lens and a near-concentric cavity are adopted for better operation. Through varying the grating period and the temperature, the tunable signal output from 1406~nm to 1513~nm is obtained. At a PPLN grating period of 29~μ m and a temperature of 413~K, a maximum signal output power of 820~mW at 1500~nm is achieved when the 808~nm pump power is 10.9~W, leading to an optical-to-optical conversion efficiency of 7.51%.  相似文献   

4.
An easily implemented method for measuring the capacitance of semiconductor structures using small-amplitude current pulses is described. It is shown that the accuracy of the method described can be improved significantly when a ballast capacitor is employed and, in addition, a calibration procedure is performed. The influence of the ballast capacitor on the measurement process is analyzed in detail. Zh. Tekh. Fiz. 69, 82–84 (March 1999)  相似文献   

5.
The correlation function of temperature fluctuations around homogeneous stationary states of the ballast resistor is evaluated by extending the theory of thermal fluctuations around equilibrium states to non-equilibrium situations. It is found that equal-time temperature fluctuations become correlated over large distances if one approaches the critical point. At the “critical point” of the ballast resistor the correlation length and the amplitude of the temperature fluctuations diverge. Furthermore the theory predicts a critical slowing down for the time-dependent temperature fluctuation correlation function. The electric noise of the system is also analyzed.  相似文献   

6.
Experiments are described in which a low-pressure mercury discharge is irradiated with a 10 ns dye laser pulse tuned resonant to one of 6 3P-7 3S1 transitions. The time behaviour of the induced optogalvanic effect is found to be dependent on the value of the ballast resistance in the discharge circuit. The qualitative explanation for this phenomenon is that the ratio of the relative change in the electron temperature and the relative change in electron density depends on the value of the ballast resistance.  相似文献   

7.
Since the tech of Pulsed Arc Electrohydraulic Discharge (PAED) found wide application, immense amounts of concrete research have been put into use on seawater treatment. When the breakdown of electrodes submerged in ballast water, strong pressure wave, ultraviolet ray, active groups, etc. can be generated, accompanying with the distinct electrohydraulic effect. Therefore, it shows the best performance on the inactivation of bacterium and seaweeds lives in the seawater. The experiment of the PAED reactor with different volume (from 10 L to 2 T) was performed step by step. The PAED power supply is 1 kJ/pulse and discharge frequency is 0.5 Hz. The best performance for the inactivation of bacterium and seaweeds by PAED is related to the conductivity of ballast water, the capacity of the treatment cell and the pulse energy. The inactivation mechanisms of PAED on ballast water will be discussed based on the electrohydraulic effect.  相似文献   

8.
利用针阴极和水阳极,在6 mm的空气隙产生了大气压空气辉光放电。该大气压辉光放电具有明显的负辉区、正柱区和阳极辉区等明亮的发光区。通过研究放电的电压电流特性,发现该放电处于亚辉光放电到正常辉光放电阶段。由于氮分子第二正带系337.1 nm的光谱强度反映高能电子密度,对337.1 nm谱线的强度进行了空间分辨测量。结果发现高能电子在针尖附近密度最大,而其他区域相差不多。随电压升高,高能电子密度减少。增大限流电阻,高能电子密度也减少。氧原子对杀菌消毒具有重要作用,利用发射光谱法对氧原子谱线强度的空间分布进行了测量,发现氧原子谱线强度与高能电子的空间分布及其随参数的变化关系一致。  相似文献   

9.
本介绍了用电容器和二极管代替低压钠灯、汞灯中镇流器的方法。  相似文献   

10.
对预热启动式电子镇流器进一步节能的途径和实验方法进行了研究,从实验中得出实验数据和结论。  相似文献   

11.
Within the fourth RTD Framework Programme, the European Union has supported a research project dealing with the improvement of railway noise (emission) measurement methodologies. This project was called MetaRail and proposed a number of procedures and methods to decrease systematic measurement errors and to increase reproducibility. In 1999 the Austrian Federal Railways installed 1000 m of test track to explore the long-term behaviour of three different ballast track systems. This test included track stability, rail forces and ballast forces, as well as vibration transmission and noise emission. The noise study was carried out using the experience and methods developed within MetaRail. This includes rail roughness measurements as well as measurements of vertical railhead, sleeper and ballast vibration in parallel with the noise emission measurement with a single microphone at a distance of 7.5 m from the track. Using a test train with block- and disc-braked vehicles helped to control operational conditions and indicated the influence of different wheel roughness.It has been shown that the parallel recording of several vibration signals together with the noise signal makes it possible to evaluate the contributions of car body, sleeper, track and wheel sources to the overall noise emission. It must be stressed that this method is not focused as is a microphone-array. However, this methodology is far easier to apply and thus cheaper. Within this study, noise emission was allocated to the different elements to answer questions such as whether the sleeper eigenfrequency is transmitted into the rail.  相似文献   

12.
Spatio-temporal patterns of the ballast resistor are investigated. It is well known that in a voltage-controlled ballast resistor an electrothermal instability leads to stable stationary states consisting of hot and cold domains. Such states may become oscillatory unstable, giving rise to the bifurcation of limit cycles. These limit cycles are not caused by the external circuit but by a recently proposed novel intrinsic mechanism. There are two types of oscillatory instabilities: bulk instabilities and boundary-induced instabilities. The bulk instabilities are caused by resistivities which are not monotonically increasing functions of the temperature. The boundary-induced instabilities occur in small systems with Neumann boundary conditions. To find the bulk instability, experiments with materials showing a metal-semiconductor transition or high-temperature superconductors are suggested. To understand these new phenomena, the equation of motion is reduced to ordinary differential equations where the instabilities can be discussed analytically.  相似文献   

13.
孙绍伍  王永超 《物理实验》2002,22(12):35-37
由实验中测出不同的灯电流波峰系数与灯开关次数的对比结果,说明了灯电流波峰系数偏高对灯寿命的影响,从而推出一种高性能低成本的电子镇流器。  相似文献   

14.
This article presents a technique for modelling the coupled dynamics of a railway vehicle and the track. The method is especially useful for simulating the dynamics of high speed trains running on nonlinear tracks. The main hypothesis is a cyclic system: an infinite track on which there is an infinite set of identical vehicles spaced at a regular interval of distance. Thus the main problems of the finite-length track models (e.g. the waves that reflect at the end of the track and interact with the vehicle; and the time interval of integration must be shorter than the track length divided by the velocity) are avoided. The flexibility of the method can be observed from the case studies presented in the present work: a vehicle passing over a hanging sleeper, and the vehicle-track dynamics for different ballast compaction cases. The results show the influence of the hanging sleeper gap on the wheel-rail contact forces, and the bending moment at the sleeper for different ballast compaction cases.  相似文献   

15.
This paper reports a continuous-wave (CW) mid-infrared intracavity singly resonant optical parametric oscillator based on periodically poled lithium niobate (PPLN) pumped by a diode-end-pumped CW Nd:YVO4 laser. Considering the thermal lens effects, it adopted an optical ballast lens and the near-concentric cavity for better operation. At the PPLN's grating period of 28.5 μm and the temperature of 140℃, the maximum idler output power of 155 mW at 3.86 μm has been achieved when the 808 nm pump power is 8.5 W, leading to an optical-to-optical conversion efficiency of 1.82%.  相似文献   

16.
The I-V characteristics of a negative corona discharge initiated by a multipoint cathode in an argon flow are experimentally studied. It is found that adjustable ballast resistances connected to the corona points provide stable operation and uniform filling of the discharge gap by the plasma.  相似文献   

17.
Self-sustained current oscillations in a Townsend discharge that is excited in a short plane discharge gap and is uniform along the electrode surface are investigated experimentally. A thin semiconductor plane serves as a discharge cathode, a ballast resistor, and an additional capacitor in the dc power supply circuit. The domain of existence and the frequency and waveform of oscillations are determined over a wide pressure range.  相似文献   

18.
Baldanov  B. B. 《Technical Physics》2011,56(4):564-566
Experimental data for a spark discharge in the tip-plane electrode configuration in argon are considered for the case when the discharge current is limited by a high-resistivity ballast resistor. It is shown that the current passing in the thin plasma channel of a low-current spark represents a steady sequence of regular pulses. It is found that low-frequency current pulses of the low-current spark are accompanied with high-frequency current oscillations of nanosecond duration.  相似文献   

19.
The transport of huge amounts of small aquatic organisms in the ballast tanks and at the hull of large cargo ships leads to ever increasing rates of marine bioinvasion. In this study, we apply a network theoretic approach to examine the introduction of invasive species into new ports by global shipping. This is the first stage of the invasion process where it is still possible to intervene with regulating measures. We compile a selection of widely used and newly developed network properties and apply these to analyse the structure and spread characteristics of the directed and weighted global cargo ship network (GCSN). Our results reveal that the GCSN is highly efficient, shows small world characteristics and is positive assortative, indicating that quick spread of invasive organisms between ports is likely. The GCSN shows strong community structure and contains two large communities, the Atlantic and Pacific trading groups. Ports that appear as connector hubs and are of high centralities are the Suez and Panama Canal, Singapore and Shanghai. Furthermore, from robustness analyses and the network’s percolation behaviour, we evaluate differences of onboard and in-port ballast water treatment, set them into context with previous studies and advise bioinvasion management strategies.  相似文献   

20.
With a destroyer, a 250 000 DWT tanker in ballast and the same tanker fully laden used as examples, data are quoted for the dynamical characteristics of dry hulls. By use of the principal co-ordinates of the dry hulls, the properties quoted are converted to generalized form in the Lagrangian sense.  相似文献   

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