Degradation of Synthetic Dyeing Wastewater by Underwater Electrical Discharge Processes

Electrical discharge treatments of synthetic dyeing wastewater were carried out with two different systems: underwater pulsed electrical discharge (UPED) and underwater dielectric barrier discharge (UDBD). Reactive Blue 4 (RB4) and Acid Red 4 (AR4) were used as model contaminants for the synthetic wastewater. The performance of the aforementioned systems was compared with respect to the chromaticity removal and the energy requirement. The results showed that the present electrical discharge systems were very effective for degradation of the dyes. The dependences of the dye degradation rate on treatment time, initial dye concentration, electrical energy, and the type of working gas including air, O 2 , and N 2 were examined. The change in the initial dye concentration did not largely affect the degradation of either RB4 or AR4. The energy delivered to the UPED system was only partially utilized for generating reactive species capable of degrading the dyes, leading to higher energy requirement than the UDBD system. Among the working gases, the best performance was observed with O 2 . As the degradation proceeded, the concentration of total dissolved solids and the solution conductivity kept increasing while pH showed a decreasing trend, revealing that the dyes were effectively mineralized.     

Discoloration of Congo Red by Rod-Plate Dielectric Barrier Discharge Processes at Atmospheric Pressure

A dielectric barrier discharge (DBD) reactor with a rod-plate electrode configuration was used for the oxidative decomposition of Congo red dye in an aqueous solution.Plasma was generated in the gas space above the water interface under atmospheric pressure.Discharge characteristics were analyzed by voltage-current waveforms.Effects of applied voltage,initial conductivity,and initial concentration were also analyzed.Congo red discoloration increased with increased applied voltage and decreased conductivity.The initial conductivity significantly influenced the Congo red discoloration.Under the same conditions,the highest discoloration rate was obtained at 25 mg/L.The presence of ferrous ions in the solutions had a substantial positive effect on Fenton dye degradation and flocculation.At an applied voltage of 20 kV,about 100％of dye was degraded after 4 min of Fe2+/DBD treatment.Results showed that adding a certain dosage of hydrogen peroxide to the wastewater could enhance the discoloration rate.Possible pathways of Congo red discoloration by DBD plasma were proposed based on GC/MS,FTIR,and UV-vis spectroscopy analyses.     

Degradation of Alizarin Red by Hybrid Gas-Liquid Dielectric Barrier Discharge

A system based on dielectric barrier discharge （DBD） with improved discharge sta- bility and homogeneity was used for the degradation of Alizarin Red （AR）. This special structure of the DBD system is characterized by the high voltage electrode, which is covered with a quartz tube and partially immersed in water, and by directly using the water as the ground electrode. A transition was realized from the filamentary mode for the conventional structure of the DBD to the semi-homogeneous mode for such a configuration of the plasma discharge. The spectra of plasma are dominated by N2 molecular lines in the ultraviolet-A radiation region. Plasma degra- dation of AR in this system exhibited pseudo-first-order reaction kinetics. The degradation rate of AR reached 95% or so after 14 min treatment under favorable conditions. Alkaline conditions are favorable for the degradation of AR. The increase of conductivity of the solution, input power and usage of oxygen bubbling could enhance AR degradation.     

Application of the Multi-Electrode in the Degradation of Alizarin Red Induced by Glow Discharge Plasma

This paper presents a novel set-up to be used in the degradation of dye, Various influencing factors, such as the voltage, the number of the anodes, and the catalytic action of Fe^2＋, were examined. Chemical oxygen demand （COD）, ultraviolet （UV）, FTIR absorption spectra, and atomic force microscopy （AFM） were used to monitor the degradation process. The results showed that the efficiency of degradation is raised by increasing the applied voltage, and is further improved when two or three anodes are used. Moreover, the use of Fe^2＋ ion can promote the degradation reaction and shorten the degradation time. So the multi-electrode instrument is more efficient in degrading the dye and should be further studied.     

PIC/MCC Simulation of Radio Frequency Hollow Cathode Discharge in Nitrogen

A two-dimensional PIC/MCC model is developed to simulate the nitrogen radio frequency hollow cathode discharge (rf-HCD).It is found that both the sheath oscillation heating and the secondary electron heating together play a role to maintain the rf-HCD under the simulated conditions.The mean energy of ions (N2+,N+) in the negative glow region is greater than the thermal kinetic energy of the molecular gas (N2),which is an important characteristic of rf-HCD.During the negative portion of the hollow electrode voltage cycle,electrons mainly follow pendulum movement and produce a large number of ionization collisions in the plasma region.During the positive voltage of the rf cycle,the axial electric field becomes stronger and its direction is pointing to the anode (substrate),therefore the ions move toward the anode (substrate) via the axial electric field acceleration.Compared with dc-HCD,rf-HCD is more suitable for serving as a plasma jet nozzle at low pressure.     

Operation Mode on Pulse Modulation in Atmospheric Radio Frequency Glow Discharges

The discharge operation regime of pulse modulated atmospheric radio frequency(RF) glow discharge in helium is investigated on the duty cycle and frequency of modulation pulses.The characteristics of radio frequency discharge burst in terms of breakdown voltage, alpha(α)-gamma(γ) mode transition voltage and current are demonstrated by the discharge current voltage characteristics. The minimum breakdown voltage of RF discharge burst was obtained at the duty cycle of 20% and frequency of 400 k Hz, respectively. The α-γ mode transition of RF discharge burst occurs at higher voltage and current by reducing the duty cycle and elevating the modulation frequency before the RF discharge burst evolving into the ignition phase, in which the RF discharge burst can operate stably in the γ mode. It proposes that the intensity and stability of RF discharge burst can be improved by manipulating the duty cycle and modulation frequency in pulse modulated atmospheric RF glow discharge.     

无线射频识别技术在核保障中的应用

为防止核材料的非法使用,增强我国的核材料管制能力,对无线射频识别（RFID）技术在核保障中应用的可靠性进行了研究。结果表明,采用一系列补充手段,可以解决核材料包装容器金属材料对RFID系统信号干扰的影响,增强目标移动探测能力,使RFID成为一种保障核材料安全的有效技术手段。     

Investigation of Atmospheric Pressure Plasma Discharge and Its Application to Surface Modification of Blood-Filtering Material

Melt-blown polybutylene terephthalate (PBT) nonwoven materials treated by using plasma is regarded as one of the excellent materials to filter white blood cells (WBC) from blood.In this paper, dielectric barrier discharge (DBD) plasma source at an improved quasi-stable atmospheric pressure is achieved when discharge voltage, discharge current, and gap between the electrodes are carefully controlled. This plasma source has been used to modify the surface of PBT melt-blown nonwoven materials. Experimental results indicate that both the wettablity and permeation of treated PBT melt-blown nonwoven materials are greatly improved.     

Ion Transport to a Photoresist Trench in a Radio Frequency Sheath

We present a model which is used to study ion transport in capacitively coupled plasma(CCP) discharge driven by a radio-frequency(rf) source for an etching process.The model combines a collisional sheath model with a trench model.The sheath model can calculate the ion energy distributions(IEDs) and ion angular distributions(IADs) to specify the initial conditions of the ions incident into the trench domain(a simulation area near and in the trench).Then,considering the charging effect on the photoresist sidewalls and the rf-bias applied to the substrate,the electric potentials in the trench domain are computed by solving the Laplace equation.Finally,the trajectories,IEDs and IADs of ions impacting on the bottom of the trench are obtained using the trench model.Numerical results show that as the pressure increases,ions tend to strike the trench bottom with smaller impact energies and larger incident angles due to the collision processes,and the existence of the trench has distinct influences on the shape of the IEDs and IADs.In addition,as the bias amplitude increases,heights of both peaks decrease and the IEDs spread to a higher energy region.     

Characteristics of Electrode-Water-Electrode Discharge and its Application to Water Treatment

Atmospheric air discharge above the surface of water is an effective method for water treatment.The leakage current and Joule heating of water are reduced by the air gap,which raises the energy efficiency of the water treatment.However,the application of this kind of discharge is limited by a pair of conflicting factors：the chemical efficiency grows as the discharge gap distance decreases,while the spark breakdown voltage decreases as the gap distance decreases.To raise the spark breakdown voltage and the chemical efficiency of atmospheric pressure water surface discharge,both the high-voltage electrode and the ground electrode are suspended above the water surface to form an electrode-water-electrode discharge system.For this system,there are two potential discharge directions：from one electrode to another directly,and from the electrodes to the water surface.The first step in utilizing the electrode-water-electrode discharge is to find out the discharge direction transition criterion.In this paper,the discharge direction transition criterions of spark discharge and streamer discharge are presented.By comparing the discharge characteristics and the chemical efficiencies,the discharge propagating from the electrodes to the water surface is proved to be more suitable for water treatment than that propagating directly between the electrodes.     

Digitized Printed Discharge Planes and Their Operation at Rapid Rates

During the last two years the development of digitized discharge planes at Brookhaven National Laboratory for operation as particle hodoscopes at rapid rates evolved from small copper wire planes to larger aluminum wire planes and later to printed circuit type thin-wall planes, which are presently in use in experiments described elsewhere in this journal.? Construction of the printed circuit planes, design of the vacuum tube pulsers and factors affecting operation of the planes are described. Attainment of a short recovrery time after a spark depends on operating with reasonably low energy in the spark, absorbing the spark energy left in the gas with quenching vapor, and applying pulsed positive ion drift fields for a preset time following the spark. Recovery time can be of the order of 20? sec in neonheliur alcohol mnixtures. Factors which affect multiplane system performance at high rates are discussed.     

Boundary Effect of Planar Glow Dielectric Barrier Discharge and Its Influence on the Discharge Structure

The dielectric barrier discharge(DBD) in the glow regime in neon has been investigated by experiment and two-dimensional(2D) fluid modeling.The discharge was carried out in a planar DBD system with segmented-electrodes driven by square-wave voltage.The results show that the glow DBD originates in the center of the electrode and expands outward to the electrode edge during each half cycle of the voltage,forming a radial structure.The discharge decays firstly in the inner area but sustains longer in the edge area,showing a reversed discharge area.The discharge cannot completely cover the entire electrode surface,but remains a border of non- or weak discharge.The fluid modeling shows a similar result in agreement with the experiments.The simulations indicate that the electric field in the edge area is distorted due to the boundary effect so that the electric field and charge distribution are different from that in the inner part.The distorted field reduces the longitudinal component near the edge and causes the local field to be lower than that in the center,and hence makes the discharge behindhand.It also induces a transverse field that makes the discharge extend radially outward to the edge.The boundary effect plays an important role in the glow DBD structure.     

A N2 Plasma Light Source Generated in Hollow Cathode Discharge and Its Application in Lithographic Plate Making

Computer to conventional plate （CTCP） technology is getting more and more attention in printing industries. In this paper we report a nitrogen plasma light source generated in hollow cathode discharge （HCD）, Which is used for pre-sensitivity （PS） plate exposure. The N2 molecule emits abundant spectrum ranging from 350 nm to 460 nm. With the voltage of 580 V, current of 1.8 A and pressure of 70 Pa in the discharge an optical power density of 0.46 mW/cm2 is obtained. The optical power density could be further increased with optimizing the lens system. The phototonus efficiency of this source is discussed in detail based upon the chemical principle and the FTIR analysis on the coating material.     

用于回旋加速器低电平系统的通用软硬件系统设计与实现

针对回旋加速器射频系统幅度、相位、频率、自动启动逻辑、联锁保护、在线参数修改等控制需求,设计了一种用于回旋加速器低电平系统的软硬件系统。该系统的硬件基于ZYNQ系列FPGA和高速ADC及DAC。采用数字下变频技术实现了幅度、相位和调谐控制;采用数字电路实现了腔体打火的快速检测。幅度控制精度为0.015%,相位控制精度为0.04°。该系统充分发挥了数字低电平系统的全可编程优势,通过上位机修改参数即可适用于多种回旋加速器。     

上海市医用X射线CT的应用频率及其分布研究

X射线CT (X-C T)的日益广泛普及,已经成为医疗照射防护中需要特别关注的热点.因此,在上海市开展的“十一五”期间医疗照射水平调查研究课题中,重点调查研究了全市医用诊断X-CT机装备及其使用的基本状况、应用频率以及所致剂量水平等.本文侧重分析全市X-CT的基本状况和应用频率及其分布的研究结果,并与世界各国现状进行了比较.截至2009年底,上海市共有112家的各级医院,使用着152台X-CT.以全市常住人口计,每百万人口X-CT拥有量逾7.9台;而全市中心区百万人均拥有量达16.9台.上海市2009年医用X-CT检查的应用频率已增至137.84人次/千人口,在医用X射线诊断的总频率中占17.7％;达到1996年的近4.2倍.进一步分析X-CT应用频率的各种分布可见,X-CT的扫描检查类型主要集中在头部、胸部和腹部;男性受检者多于女性;且以年龄大于40岁者居多等.最后针对有关医疗照射水平调查研究和相应大力加强X射线CT检查的医疗照射防护问题展开了具体讨论.     

Aerosol,Gas, and Swarf Production during Underwater Cutting of Reactor Core Internals Using Electron Discharge Machining

Secondary products (aerosol, gas and swarf) are released in the work area when cutting nuclear reactor components are underwater during component replacement. We studied the characteristics and behavior of the secondary products produced during cutting of highly radioactive metals using electric discharge machinery (EDM) underwater. The ratio of the weight of the aerosol produced to the melted weight of a workpiece that was cut using EDM, both with a Ag/W alloy electrode and a carbon electrode, was about 1 × 10^?3. The aerosol had a high concentration of manganese with a high vapor pressure. The production ratio was expressed as the aerosol production rate (ppm) = ?4:6 × 10^?2 Tb + 1:4 × 10² (Tb: boiling point (K)). The EDM cutting produced metal vapors which condensed into particles. Air-borne nickel carbonyl was produced during the EDM cutting of nickel and carbon monoxide with a carbon electrode, and a high efficiency particulate air filter and a charcoal filter were used effectively. In the case of a Ag/W electrode, the swarf contained oxide particles of around 20 mm and hydroxide particles with a diameter of around 10 mm. The water clean-up system was able to purify water with over 95% filtration efficiency using a 1 μm pore-pleated filter cartridge.     

线粒体DNA突变及其在生物剂量估算中的应用探讨

介绍了线粒体DNA（mtDNA）的结构特点和功能,对突变类型和可能的机制进行了分析。着重阐述了电离辐射所致的mtDNA突变,对利用mtDNA突变建立辐射生物剂量计的可行性作了初步探讨。     

离子束生物技术及其在玉米育种中的应用

离子束作为一种新兴诱变源,已广泛应用于各种农作物的诱变育种。离子束生物技术为玉米品种的改良和种质资源的创新开辟了一条新的道路,推动了玉米育种事业的长足发展。本文阐述了离子束的特点、诱变机理以及在玉米育种中的应用。     

电网频率变化对压水堆机组运行的影响分析及应对措施

在世界核营运者协会(WANO)分析过的多起事件中,操纵员完全依赖反应堆保护系统来保护堆芯,而不是优先采取保守行动。尤其是在发生规程未覆盖的电网异常工况时,由于操纵员缺乏经验可能使工况进一步恶化。分析电网频率变化对压水堆机组运行的潜在不利影响,提出应对措施,使操纵员在遇到此类电网异常工况时能及时作出正确的响应,避免反应堆保护系统动作来保护堆芯,以保守地监控压水堆机组运行,始终保持电厂的安全限值有足够的安全裕度。     

Excited Electron Temperature and Molecular Vibration Temperature During Transition from Filamentary Discharge to Glow Discharge in Surface Discharge in Air

A dielectric barrier surface discharge device was used to investigate the transition from a filamentary discharge to a glow discharge in air at different gas pressures. Discharge images and waveforms of the applied voltage and discharge current were recorded simultaneously, and it was found that the discharge could transit from filamentary to glow with the decrease in pressure. Optical emission spectra during the transition from a filamentary discharge to a glow one were recorded. Excited electron temperature can be determined from the ratios of the relative intensities of spectral lines while molecular vibration temperature can be measured by analysing spectral lines of the N2 second positive band system. The results show that both the excited temperature and molecular vibration temperature increase with the decrease in the gas pressure. Qualitative explanations are given.