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collection efficiency of a monitor parallel plate ionization chamber for pencil beam scanning proton therapy

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Nuclear Science and Techniques 2020年第2期31卷 1-10页

作者： Rong-Cheng Han Yong-Jiang Li Yue-Hu Pu Shanghai Institute of Applied Physics Chinese Academy of SciencesShanghai 201800China University of Chinese Academy of Sciences Beijing 100049China Shanghai APACTRON Particle Equipment Co.Ltd Shanghai 201800China Shanghai Advanced Research Institute Chinese Academy of SciencesShanghai 201210China

The collection efficiency of monitor parallel plate ionization chambers is the main uncertainty in the beam control of pencil beam scanning systems.Existing calculation methods for collection efficiency in photon or passive scattering proton systems have not considered the characteristics of non-uniform charge density in pencil beam scanning systems.In this study,Boag’s theory was applied to a proton pencil beam scanning system.The transverse distribution of charge density in the ionization chamber was considered to be a Gaussian function and an analytical solution was derived to calculate collection efficiency in the beam spot area.This calculation method is called the integral method and it was used to investigate the effects of beam parameters on collection efficiency.It was determined that collection efficiency is positively correlated with applied voltage,beam size,and beam energy,but negatively correlated with beam current intensity.Additionally,it was confirmed that collection efficiency is improved when the air filling the monitor parallel plate ionization chamber is replaced with nitrogen.

关键词： collection efficiency Monitor ionization chamber Pencil beam scanning Proton therapy

Effects of Different Rainwater Diversion Patterns on Rainwater collection efficiency and Water Utilization efficiency in Cornfield

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Meteorological and Environmental Research 2015年第8期6卷 54-56页

作者： Wang Jianxin Wang Panlei Duan Zongyan Pan Yanhua Chen Shihua Lu Yao Institute of Agricultural Resources & Environment Yunnan Academy of Agricultural Sciences

Four rainwater diversion patterns including undisturbed soil ditch （T1）, slope compaction （T2）, asbestos sheet covering after compac- tion （T3） and plastic film covering after compaction （T4） were set in cornfield in arid areas of Yunnan Province, and effects of various patterns on rainwater collection efficiency, water utilization efficiency and corn yield were studied. The results shows that rainwater collection efficiency, water utilization efficiency and corn yield of the four diversion patterns presented the same trend, namely T4 〉T3 〉T2 〉T1. Overall, rainwater collection efficiencies of the four diversion patterns ranged from 41.7% to 58.7% ; compared with T1, water utilization efficiencies of T2 ,T3 and T4 increased by 34.9%, 53.5% and 92.5%, and maize yields of them improved by 1 767.0, 1 981.5 and 2 385.0 kg/hm2.

关键词： Arid areas of Yunnan Maize Diversion pattern collection efficiency Water utilization efficiency China

Influence of wire spacing and plate spacing on electrostatic precipitation of nanoparticles: An approach involving electrostatic shielding and diffusion charging

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Particuology 2023年第9期80卷 127-139页

作者： Felipe de Aquino Lima Vádila Giovana Guerra Department of Chemical Engineering Federal University of São CarlosRodovia Washington LuísKm 235C.P.676CEP 13560-970São CarlosSPBrazil

Electrostatic precipitation is a process widely used as gas cleaning device,to removal particles from gas flows.However,in a conventional and well-sized precipitator,the collection efficiency decreases for ultrafine particles,making it difficult to employ this equipment for controlling nanoparticle pollution.This paper investigates the influence of plate spacing(4 and 6.5 cm)and wire spacing(4,6,and 12 cm)on the electric current and nanoparticle collection efficiency,considering the effect of diffusion charging and electrostatic shielding.Two laboratory-scale dry wire-plate electrostatic precipitators with different plate spacings were tested for the collection of nanoparticles(6.15–241.4 nm)at three air velocities(1.9,2.9,and 3.9 cm/s).The results demonstrated the effectiveness of the equipment in removing nanoparticles(99.9%)under the highest electric fields.Higher values of the wire spacing led to increases in the current and the collection efficiency.This was associated with reduced electrostatic shielding,which is more evident in smaller ducts with a higher density of field lines.It is expected that the findings should improve knowledge on electrostatic precipitation of nanoparticles,enabling optimization of collection efficiency by considering the effects of geometric parameters.

关键词： Electrostatic precipitation Nanoparticles collection efficiency Plate spacing Wire spacing

Experimental and numerical study of a gas cyclone with a central filter

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Particuology 2022年第4期20卷 47-59页

作者： Zihui Zhang Sijie Dong Kejun Dong Li'an Hou Wenzheng Wang Yi Wei Bo Wang Key Laboratory of Western China's Environmental Systems(Ministry of Education)and Engineering Research Center of Fine Particles Pollution Control Technology and Equipment of Gansu Province College of Earth and Environmental SciencesLanzhou UniversityLanzhou 730000China Centre for Infrastructure Engineering School of EngineeringWestern Sydney UniversityPenrithNSW 2751Australia Xi'an High-Tech Institute Xi'an 710025China Gansu Chemical Industry Research Institute Co. Ltd.Lanzhou 730000China

This paper studies a novel gas cyclone with a cylindrical fiter face installed in the center from the vortex finder to the bottom hopper.The experimental results show that this composite cyclone has a higher collection fficiency and a lower pressure drop than the original cyclone.The mechanisms for the improvement are analyzed by both physical experiments and numerical simulations.By measuring dust samples collected at different places it is revealed that the center filter can prevent fine particles from entering the inner vortex and escaping,which accounts for the increase of the collection eficiency.In addition,the flow field of the composite cyclone is simulated by computational fluid dynamics and compared with that of the original cyclone.The analysis shows that with the filter layer installed,the swirling flow disappears in the vortex finder,which decreases the kinetic energy dissipation and hence lowers the pressure drop.

关键词： Cyclone Filtration Porous media model collection efficiency Pressure drop

Bipolar charged aerosol agglomeration and collection by a two-zone agglomerator

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Journal of Environmental Sciences 2001年第3期13卷 276-279页

作者： XIANG Xiao dong 1, CHEN Bao zhi 1, COLBECK I 2 (1. School of Resource and Civil Engineering, Northeastern University, Shenyang 110006, China. 2. Institute for Environmental Research, Department of Biological and Chemical Sciences, University of Es School of Resource and Civil Engineering Northeastem University Shenyang 110006 China. E-mail:[email protected]mail. neu. cn Institute for Environmental Research Department of Biological and Chemical Sciences University of Essex Colchester CO4 3SQ UK

In older to collect fine particles more efficiently, a new-type electrostatic agglomerator with two zones was developed. The distinguishing feature of this electrostatic agglomerator is that the particles are bipolarly charged and coagulated in the same alternating electric field simultaneously. The silica flour with 2 fun mass median diameter and the smoke from burning wood powder were used as test aerosol. The comparison experimental results have shown that when the mean electric field is 4 kV/cm the collection efficiency of the new electrostatic agglomerator was 98.2% for silica flour and 67.4% for wood powder smoke, Under the same experimental condition. the collection efficiency of the electrostatic agglomerator with three zones was 97.4% for collecting silica flour and the collection efficiency of the electrostatic precipitator was 56.3% for wood powder smoke.

关键词： charged particle agglomeration alternating electric field electrostatic agglomerator (EA) electrostatic precipitator (ESP) collection efficiency

Collecting aerosol in airflow with a magnetically stabilized fluidized bed

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Journal of Environmental Sciences 2001年第4期13卷 497-501页

作者： Gui, KT Zhang, H Shi, MH Xu, YQ SE Univ Dept Power Engn Nanjing 210096 Peoples R China

A magnetically stabilized fluidized bed (MSB) is a highly efficient filter that takes the advantage of both fluidized beds and fixed beds. This paper presents the research to collect aerosol in airflow with a MSB. The filtering model of MSB is established with its parameters including magnetic Geld intensity, gas superficial velocity, average grain-size, and bed height on the collection efficiency of MSB. The model is verified by experiments.

关键词： magnetically stabilized fluidized bed filtering model collection efficiency

Separating polydisperse particles using electrostatic precipitators with wire and spiked-wire discharge electrode design

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Particuology 2018年第3期16卷 10-17页

作者： Soren Sander Steffen Gawor Udo Fritsching Process Engineering Stiftung Institut ffir Werlcstofftechnik Badgasteiner Strasse 3 28359 Bremen Germany Particles and Process Engineering University of Bremen Bibliothekstrasse 1 28359 Bremen. Germany

Numerical simulations of electrostatic precipitators featuring wire and spiked electrode designs were performed to determine particle behavior and separation efficiency. The applied-voltage mechanism that alters the flow structure of particles through ionic winds and mean electric fields are revealed. Numeri- cal studies throughout the past years have shown these structures for channel and pipe configurations. However, less attention was given to field averaging for the ni,~r-product and electric field. Our study focuses on this averaging and illustrates relevant differences between multidimensional setups concern- ~ng these fields. Turbulence was modeled using the Reynolds-averaged Navier-Stokes equations with a second-order Reynolds-stress-model closure. A high three-dimensionality of the ionic wind-induced turbulence is presented. This leads to an increase in the submicron-particle precipitation rate. The results confirm the dependence of separation efficiency on particle density and permittivity, thereby showing the advantages of spiked wires compared with wire-plate setups used in electrostatic precipitators.

关键词： Electro-hydrodynamic CFD simulation Electrostatic particle precipitation Electrode design collection efficiency

Beaming light from a quantum emitter with a planar optical antenna

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Light(Science & Applications) 2016年第1期5卷 20-27页

作者： Simona Checcucci Pietro Lombardi Sahrish Rizvi Fabrizio Sgrignuoli Nico Gruhler Frederik BC Dieleman Francesco S Cataliotti Wolfram HP Pernice Mario Agio Costanza Toninelli European Laboratory for Nonlinear Spectroscopy(LENS) 50019 Sesto FiorentinoItaly National Institute of Optics(CNR-INO) 50019 Sesto FiorentinoItaly Dipartimento di Fisica ed Astronomia Universitàdegli Studi di Firenze50019 Sesto FiorentinoItaly Center for Quantum Science and Technology in Arcetri(QSTAR) 50125 FlorenceItaly Institute of Nanotechnology Karlsruhe Institute of Technology(KIT)76344 Eggenstein-LeopoldshafenGermany Institute of Physics University of Muenster48149 MuensterGermany The Blackett Laboratory Department of PhysicsImperial College LondonLondon SW72AZUK Laboratory of Nano-Optics University of Siegen57072 SiegenGermany

The efficient interaction of light with quantum emitters is crucial to most applications in nano and quantum photonics,such as sensing or quantum information processing.Effective excitation and photon extraction are particularly important for the weak signals emitted by a single atom or molecule.Recent works have introduced novel collection strategies,which demonstrate that large efficiencies can be achieved by either planar dielectric antennas combined with high numerical aperture objectives or optical nanostructures that beam emission into a narrow angular distribution.However,the first approach requires the use of elaborate collection optics,while the latter is based on accurate positioning of the quantum emitter near complex nanoscale architectures;hence,sophisticated fabrication and experimental capabilities are needed.Here we present a theoretical and experimental demonstration of a planar optical antenna that beams light emitted by a single molecule,which results in increased collection efficiency at small angles without stringent requirements on the emitter position.The proposed device exhibits broadband performance and is spectrally scalable,and it is simple to fabricate and therefore applies to a wide range of quantum emitters.Our design finds immediate application in spectroscopy,quantum optics and sensing.

关键词： collection efficiency fluorescence microscopy optical nano-antennas single molecule

NUMERICAL SIMULATION OF THREE DIMENSIONAL GAS-PARTICLE FLOW IN A SPIRAL CYCLONE

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Applied Mathematics and Mechanics(English Edition) 2006年第2期27卷 247-253页

作者：王灿星易林 College of Mechanical and Energy EngineeringZhejiang University Hangzhou 310027 P. R. China

The three-dimension gas-particle flow in a spiral cyclone is simulated nu- merically in this paper. The gas flow field was obtained by solving the three-dimension Navier-Stokes equations with Reynolds Stress Model （RSM）. It is shown that there are two regions in the cyclone, the steadily tangential flow in the spiral channel and the combined vortex flow in the centre. Numerical results for particles trajectories show that the initial position of the particle at the inlet plane substantially affects its trajectory in the cyclone. The particle collection efficiency curves at different inlet velocities were obtained and the effects of inlet flow rate On the performance of the spiral cyclone were presented. Numerical results also show that the increase of flow rate leads to the increase of particles collection efficiency, but the pressure drop increases sharply.

关键词： spiral cyclone numerical simulation particle trajectory collection efficiency