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Aerodynamic actuation characteristics of radio-frequency discharge plasma and control of supersonic flow
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作者 杨臻 宋慧敏 +3 位作者 王宏宇 郭善广 贾敏 王康 《中国物理B:英文版》 SCIE EI CAS CSCD 2019年第2期321-330,共10页
In this paper, aerodynamic actuation characteristics of radio-frequency(RF) discharge plasma are studied and a method is proposed for shock wave control based on RF discharge. Under the static condition, a RF diffuse ... In this paper, aerodynamic actuation characteristics of radio-frequency(RF) discharge plasma are studied and a method is proposed for shock wave control based on RF discharge. Under the static condition, a RF diffuse glow discharge can be observed;under the supersonic inflow, the plasma is blown downstream but remains continuous and stable.Time-resolved schlieren is used for flow field visualization. It is found that RF discharge not only leads to continuous energy deposition on the electrode surface but also induces a compression wave. Under the supersonic inflow condition, a weak oblique shock wave is induced by discharge. Experimental results of the shock wave control indicate that the applied actuation can disperse the bottom structure of the ramp-induced oblique shock wave, which is also observed in the extracted shock wave structure after image processing. More importantly, this control effect can be maintained steadily due to the continuous high-frequency(MHz) discharge. Finally, correlations for schlieren images and numerical simulations are employed to further explore the flow control mechanism. It is observed that the vortex in the boundary layer increases after the application of actuation, meaning that the boundary layer in the downstream of the actuation position is thickened. This is equivalent to covering a layer of low-density smooth wall around the compression corner and on the ramp surface, thereby weakening the compressibility at the compression corner. Our results demonstrate the ability of RF plasma aerodynamic actuation to control the supersonic airflow. 展开更多
关键词 radio-frequency(RF) DISCHARGE PLASMA surface DISCHARGE FLOW control aerodynamic ACTUATION
Relation between etching profile and voltage-current shape of sintered SiC etching by atmospheric pressure plasma
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作者 D C SEOK S R YOO +2 位作者 K I LEE Y S CHOI Y H JUNG 《等离子体科学与技术:英文版》 SCIE EI CAS CSCD 2019年第4期137-144,共8页
Sintered silicon carbide(SiC)was etched by a dielectric barrier discharge source.A high voltage bipolar pulse was used with helium gas for the plasma generation.One stable filament plasma was generated and could be us... Sintered silicon carbide(SiC)was etched by a dielectric barrier discharge source.A high voltage bipolar pulse was used with helium gas for the plasma generation.One stable filament plasma was generated and could be used for SiC etching.As the processing gas(NF3)mixing rate increased,the width and depth of the etching profile became narrower and deeper.The differentiated V-Q Lissajous method was used for measuring the capacitances(Ceq)of the electrode after the plasma turned on.The width of the etching profile was proportional to Ceq.As the current peak value/smx of the substrate current in creased,the volume removal rate of SiC increased.The etch depth was proportional to the ratio of/smx to Ceq.Additionally,because of the different characteristics of the plasma disks on SiC substrate by the voltage polarity,the etching profile was unstable.However,in high NF3 mixing process,the etching profile became stable and deeper. 展开更多
关键词 dielectric BARRIER DISCHARGE silicon CARBIDE plasma etching、filament discharge surface charge
隧道砂层段排水性能对水压与排水量的影响 预览
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作者 刁钰 贾镇阳 +3 位作者 李光帅 褚振西 高泽东 郭勇志 《水利水电技术》 北大核心 2019年第4期23-31,共9页
为保证运营期某隧道衬砌结构安全提供理论依据,需提出排水量与衬砌水压荷载之间的关系。通过ABAQUS数值模拟软件,将模型中隧道排水系统和初支统一视为一层排水介质,简化为一维第三类边界条件,并利用温度场与渗流场的对应关系,使用温度... 为保证运营期某隧道衬砌结构安全提供理论依据,需提出排水量与衬砌水压荷载之间的关系。通过ABAQUS数值模拟软件,将模型中隧道排水系统和初支统一视为一层排水介质,简化为一维第三类边界条件,并利用温度场与渗流场的对应关系,使用温度场模拟渗流场,在保证精度的同时,极大的提高了计算效率。对数值模拟出的变量关系进行曲线拟合,以得到简化计算公式。研究表明,对于本工程,流量与水压1个月内迅速下降并稳定。初支渗透性减小,隧道压力水头增加。当表面渗透系数K≤3×10^-5 d^-1时,可认为初支不透水,承担全部水压;当K≥3 d^-1时,可认为初支完全透水,不承担水压力,不影响隧道排水;当表面渗透系数3×10^-5≤K≤3 d^-1时,稳定水头高于设计水头,承担部分水压力。拟合公式可以合理反应表面渗透系数、水头、排水量、时间的相互关系。 展开更多
关键词 隧道 砂层 排水量 水头 数值模拟 渗流场 堵水限排
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Study on the discharge mechanism and EM radiation characteristics of Trichel pulse discharge in air
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作者 王闯 陈曦 +1 位作者 唐凯 李鹏斐 《等离子体科学与技术:英文版》 SCIE EI CAS CSCD 2019年第5期113-120,共8页
The Trichel pulse stage is an unstable stage of negative corona discharge that can also involve electromagnetic(EM)radiation signals.In this paper,the discharge mechanism and radiation characteristics of the Trichel p... The Trichel pulse stage is an unstable stage of negative corona discharge that can also involve electromagnetic(EM)radiation signals.In this paper,the discharge mechanism and radiation characteristics of the Trichel pulse are studied in the needle-plate electrode configuration.The Trichel pulse currenl and its EM radiation signals are measured at different applied voltages.The results show that Trichel pulse discharge changes from the nindom pulse stage to the continuous pulse stage as the applied voltage increases.During these different stages,the normalized shape of the Trichel pulses remains unchanged,while the frequency of the EM radiation generated by the discharge remains unchanged.The discharge mechanism and EM radiation characteristics of the Trichel pulse are theoretically analyzed in the different stages.Both the positive ion sheath and the negative ion cloud play key roles in the formation of the Trichel pulse.The EM radiati on signal is generated by the rapidly changing Trichel pulse current,and the Trichel pulse current waveform determines the characteristics of the EM radiation signal. 展开更多
关键词 NEGATIVE CORONA DISCHARGE Trichel PULSE EM RADIATION DISCHARGE mechanism
Experimental study of rotating gliding arc discharge plasma-assisted combustion in an aero-engine combustion chamber
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作者 Liming HE Yi CHEN +3 位作者 Jun DENG Jianping LEI Li FEI Pengfei LIU 《中国航空学报:英文版》 SCIE EI CAS CSCD 2019年第2期337-346,共10页
The combustion chamber is the core component of an aero-engine, and affects its reliability and security operation, even the performance of the aircraft. In this work, a Plasma-Assisted Combustion(PAC) test platform w... The combustion chamber is the core component of an aero-engine, and affects its reliability and security operation, even the performance of the aircraft. In this work, a Plasma-Assisted Combustion(PAC) test platform was developed to validate the feasibility of using PAC actuators to enhance annular combustor performance. Two plans of PAC(rotating gliding arc discharge plasma) were designed, Assisted Combustion from Primary Holes(ACPH) and Assisted Combustion from Dilution Holes(ACDH). Comparative experiments and analysis between conventional combustion and PAC were conducted to study the effects of ACPH and ACDH on the performances including average outlet temperature, combustion efficiency, pattern factor under four different excessive air coefficients(0.8, 1, 2, and 4), and lean blowout performance at different inlet airflow velocities. Experimental results show that the combustion efficiency is improved after PAC compared with that in normal conditions, and the combustion efficiency of ACPH increases2.45%, 1.49%, 1.04%, and 0.47%, while it increases 2.75%, 1.67%, 1.36%, and 0.36% under ACDH conditions. The uniformity of the outlet temperature field and the lean blowout performance are improved after PAC. Especially for ACPH, the widening of the lean blowout limit is8.3%, 12.4%, 12.8%, and 25% respectively when the inlet velocity ranges from 60 m/s to120 m/s. These results offer new perspectives for using PAC devices to enhance aero-engine combustors’ performances. 展开更多
关键词 AERO-ENGINE Assisted COMBUSTION ACTUATOR COMBUSTION CHAMBERS Plasma-Assisted COMBUSTION ROTATING GLIDING arc discharge
The effects of gas flow pattern on the generation of ozone in surface dielectric barrier discharge
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作者 谢松汝 何勇 +4 位作者 袁定琨 王智化 Sunel KUMAR 朱燕群 岑可法 《等离子体科学与技术:英文版》 SCIE EI CAS CSCD 2019年第5期168-178,共11页
Ozone production utilizing surface dielectric barrier discharge(SDBD)was experimental studied for different flow patterns considering the influences of transversal flow,lateral flow and different lateral flow position... Ozone production utilizing surface dielectric barrier discharge(SDBD)was experimental studied for different flow patterns considering the influences of transversal flow,lateral flow and different lateral flow positions.Results show that the flow patterns have a remarkable impact on the ozone yield by affecting the uniformity and turbulenee of gas flow.Meanwhile,distributing the O2 flow rate according to the intensity of the plasma reaction would also increase the generation efficiency of SDBD for ozone production.By improving the uniformity and introducing the lateral flow to the transversal flow,the highest ozone yield was obtained in flow pattern'F‘.In this case,the ozone yield increased by 28.4%to 131 g kWh^-1 from 102.8 g kWh^-1 in flow pattern‘A’. 展开更多
关键词 surface DIELECTRIC BARRIER DISCHARGE gas flow OZONE generation
Thermodynamic Analysis of a Modified Ejector-Expansion Refrigeration Cycle with Hot Vapor Bypass
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作者 LI Yunxiang YU Jianlin 《热科学学报:英文版》 SCIE EI CAS CSCD 2019年第4期695-704,共10页
In this study,a modified ejector-expansion refrigeration cycle(MERC)is proposed for applications in small refrigeration units.A vapor bypass circuit is introduced into the standard ejector expansion refrigeration cycl... In this study,a modified ejector-expansion refrigeration cycle(MERC)is proposed for applications in small refrigeration units.A vapor bypass circuit is introduced into the standard ejector expansion refrigeration cycle(ERC)for increasing the ejector pressure lift ratio,thereby lowering the compressor pressure ratio in the MERC.A mathematical model has been established to evaluate the performances of MERC.Analysis results indicate that since a two phase vapor-liquid stream is used to drive the ejector in the MERC,a larger ejector pressure lift ratio can be achieved.Thus,the compressor pressure ratio decreases by 21.1%and the discharge temperature reduces from 93.6℃to 82.1℃ at the evaporating temperature of-55℃ when the vapor quality of two phase vapor-liquid stream increases from 0 to 0.2.In addition,the results show that the higher ejector component efficiencies are effective to reduce the compressor pressure ratio and the discharge temperature.Actually,the discharge temperature reduces from 91.4℃ to 82.1℃ with the ejector component efficiencies increasing from 0.75 to 0.85 at the two phase stream vapor quality of 0.2.Overall,the proposed cycle is found to be feasible in lower evaporating temperature cases. 展开更多
关键词 COMPRESSOR pressure ratio DISCHARGE temperature EJECTOR REFRIGERATION cycle vapor BYPASS
Breakdown characteristics of CF3I/N2/CO2 mixture in power frequency and lightning impulse voltages
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作者 林启明 赵谡 +1 位作者 肖登明 周柏杰 《等离子体科学与技术:英文版》 SCIE EI CAS CSCD 2019年第1期36-43,共8页
Trifluoroiodomethane(CF3I) and its mixtures are believed to be prospective alternatives to sulfur hexafluoride(SF6), which has been included as a greenhouse gas. In this paper, the breakdown properties of a CF3I/N2/CO... Trifluoroiodomethane(CF3I) and its mixtures are believed to be prospective alternatives to sulfur hexafluoride(SF6), which has been included as a greenhouse gas. In this paper, the breakdown properties of a CF3I/N2/CO2 mixture with the volume fraction of CF3I fixed at 10% are investigated under power frequency and lightning impulse voltages. The experimental result shows that N2 possesses higher power frequency and negative lightning impulse breakdown voltages than CO2, but the power frequency and more negative lightning impulse breakdown voltages of the CF3I/N2/CO2 mixture do not increase with the content of N2. For the purpose of explaining this abnormal phenomenon, the ionization energies and excitation energies of CF3I,N2and CO2 are calculated. The computation results indicate that the ionization energy of CF3I is lower than the first excitation energy of N2, but higher than the lowest excitation energy of CO2,which means that CF3I molecules are easily ionized by metastable N2 molecules. The first excitation energy of N2 is too high, which hinders its application as the buffer gas of CF3I. 展开更多
关键词 GAS DISCHARGE CF3I GAS MIXTURES Penning EFFECT BUFFER GAS
GRACE observed mass loss in the middle and lower Yangtze basin
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作者 Jiangjun Ran Natthachet Tangdamrongsub +3 位作者 Junchao Shi Changqing Wang Lihui Wang Xiaoyun Wan 《大地测量与地球动力学:英文版》 2019年第2期157-162,共6页
Anthropogenic architectures have a significant impact to the environment. The Three Gorges Dam(TGD),as the largest dam in the world, is a typical example, and has influenced the mass anomalies transported by the flow ... Anthropogenic architectures have a significant impact to the environment. The Three Gorges Dam(TGD),as the largest dam in the world, is a typical example, and has influenced the mass anomalies transported by the flow downstream in the Yangtze River since June 2003. However, the evidence of TGD influence on downstream mass transportation is not documented. In this study, we analyze the monthly gravity solutions from GRACE to investigate the downstream mass variations of Yangtze River. From our results,the considerable mass loss is detected in the downstream of TGD. By comparing our estimations with the in situ water level data of TGD, we find that the mass variations derived from GRACE at Datong station decreases shortly after the impoundment of TGD. This confirms a strong connection between them.Furthermore, by comparing with the in situ sediment load and river discharge at Yichang and Datong gauging stations, we find that the sediment load data shows a similar mass loss signature while the river discharge of both stations has stay at a relative stable level. This indicates that further study is still needed to understand the mechanism better. 展开更多
关键词 GRACE Mass loss The YANGTZE RIVER BASIN Sediment load RIVER discharge
平原感潮河网地区河道洪水对村镇内涝的影响 预览
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作者 魏乾坤 刘曙光 +2 位作者 钟桂辉 胡子琛 姚忠明 《长江科学院院报》 CSCD 北大核心 2019年第3期46-52,共7页
随着平原感潮河网地区城市化快速发展,下垫面变化落后导致河道泄洪能力不足,河道洪水水位明显上涨,村镇内涝灾害日益频繁,已明显制约当地经济发展。在分析平原感潮河网地区村镇内涝影响因素基础上,以典型村镇为例,通过数值模拟方法分析... 随着平原感潮河网地区城市化快速发展,下垫面变化落后导致河道泄洪能力不足,河道洪水水位明显上涨,村镇内涝灾害日益频繁,已明显制约当地经济发展。在分析平原感潮河网地区村镇内涝影响因素基础上,以典型村镇为例,通过数值模拟方法分析该地区河道洪水对村镇内涝影响。结果显示50a一遇与100a一遇河道洪水分别导致村镇排涝水量减少25.17%,55.24%,排涝水量减少对村镇内部河流洪水过程的影响明显。降雨量增大加剧了排涝水量减少对村镇内涝淹没面积扩大的影响。河道洪水可导致村镇内涝淹没面积扩大22%,加剧了村镇内涝灾情。此研究成果可为该地区村镇内涝风险管理提供参考。 展开更多
关键词 平原感潮河网地区 河道洪水 村镇内涝 排涝水量 数值模拟
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Design and preliminary experiment of radial sheet beam terahertz source based on radial pseudospark discharge
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作者 张点 张军 +2 位作者 李嵩 刘静 钟辉煌 《等离子体科学与技术:英文版》 SCIE EI CAS CSCD 2019年第4期22-26,共5页
To satisfy the demands for compact,inexpensive terahertz(THz)sources with power of hundreds of watts,a radial sheet beam THz source which does not require an external magnetic field and is driven by a radial pseudospa... To satisfy the demands for compact,inexpensive terahertz(THz)sources with power of hundreds of watts,a radial sheet beam THz source which does not require an external magnetic field and is driven by a radial pseudospark discharge plasma electron gun(PSDP-EGUN)is proposed.Radial design has been used in pseudospark switches,but in this paper the design of a PSDP-EGUN to drive a radial THz source is presented for the first time.Being different from the latest reported axial quasi-rectangular sheet beam THz sources driven by an axial PSDP-EGUN,a new desig n consisti ng of a circular plate-shaped sheet beam that is directly gen erated by the radial PSDP-EGUN is reported.As compared to an axial system,the radial configuration may result in a larger beam current and a larger beam-wave interaction area together with a higher potential of THz output power.Theoretical analysis and pailicle-in-cell simulation have been employed in the design of the radial sheet beam THz source.Output powers in the kilowatt range have been observed in the simulation of this 0.22 THz source.Preliminary experimental results of the radial PSDP-EGUN are also presented. 展开更多
关键词 SHEET BEAM TERAHERTZ source PSEUDOSPARK DISCHARGE
Plasma-assisted Ru/Zr-MOF catalyst for hydrogenation of CO2 to methane
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作者 徐卫卫 张秀玲 +2 位作者 董梦悦 赵静 底兰波 《等离子体科学与技术:英文版》 SCIE EI CAS CSCD 2019年第4期27-33,共7页
As an important type of metal-organic framework(MOF),Zr-MOF shows excellent CO2 adsorption performance.In this work,a Zr-MOF was synthesized by a solvothennal method and adopted to support Ru through simple incipient-... As an important type of metal-organic framework(MOF),Zr-MOF shows excellent CO2 adsorption performance.In this work,a Zr-MOF was synthesized by a solvothennal method and adopted to support Ru through simple incipient-wetness impreg nation.Then the Ru/Zr-MOF was applied for CO2 hydrogenation(Vh2:VCO2=4:1)with the assistance of dielectric banner dischai'ge(DBD)plasma.The hydrogenation of Cd2 results showed that methane was produced selectively under the synergistic effect between plasma and the Ru/Zr-MOF catalyst,and the selectivity and yield of methane reached 94.6%and 39.1%,respectively.The XRD and SEM analyses indicate that the basic crystalline phase structure and morphology of the Zr-MOF and Ru/Zr-MOF remained the same after DBD plasma treatment,suggesting that the catalysts are stable in plasma.The guest molecules in the pores of the Zr-MOF are removed and the Ru"ions are reduced to metallic Ru()in the reduction atmosphere according to the BET and XPS results,which are responsible for the high performance of plasma with the Ru/Zr-MOF catalyst.In situ optical emission spectra of pure plasma,plasma with Zr-MOF,and plasma with Ru/Zr-MOF were measured,and the active species of C,H and CH for CO2 hydrogenation were detected.The plasma-assisted Ru/Zr-MOF exhibited high catalytic activity and stability in CO2 hydrogenation to methane,and it has great guiding significance for CO2 hydrogenation by using plasma and MOF materials. 展开更多
关键词 dielectric BARRIER DISCHARGE cold plasma.Zr-MOF carbon dioxide hydrogenation methane
Simple reactor for the synthesis of silver nanoparticles with the assistance of ethanol by gas-liquid discharge plasma
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作者 Pan LU Dong-Wook KIM Dong-Wha PARK 《等离子体科学与技术:英文版》 SCIE EI CAS CSCD 2019年第4期34-43,共10页
Atmospheric pressure plasma technology is gaining increasing importance because it is a simple and tunable synthesis process for the production of metallic nanoparticles.In addition to the development of the power sup... Atmospheric pressure plasma technology is gaining increasing importance because it is a simple and tunable synthesis process for the production of metallic nanoparticles.In addition to the development of the power supply,improving the reactor is also one of the main strategies to enhanee the utility.In this study,a simple reactor for the gas-liquid discharge plasma induced by argon gas was applied to synthesize silver nanopailicles from silver nitrate(AgNO3)in solution.An AC power supply with a peak voltage of 3.5 kV was used.The frequency and on-time were set to 50 kHz and 2.5“s,respectively.The oscilloscope showed that the rising time was approximately 2“s.The ethanol was used as the source for the reactive reducing agent.No more additional comp on ents existed in the solution during the discharge and neither of the electrodes was in contact with the treated solution.The temperature in creased by 10°C within 1 min without a cooling system.Carbon was the main impurity and was expected to be produced from the decomposition of the organics under the plasma.The elevated temperature decreased the organic by-products by evaporation and could also decrease the production of carbon.Transmission electron microscopy showed that the spherical silver nanoparticles with a size of approximately 10 nm were synthesized with a crystal structure and that a low concentration of ethanol prefers the production of the mono-dispersed colloid. 展开更多
关键词 silver nanoparticles synthesis nonthermal plasma ETHANOL reduction GAS-LIQUID DISCHARGE
Influe nee of gas atmosphere on synergistic control of mercury and dioxin by nonthermal plasma
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作者 竹涛 边文璟 +3 位作者 马名烽 叶维丽 王若男 张星 《等离子体科学与技术:英文版》 SCIE EI CAS CSCD 2019年第4期44-51,共8页
In this paper,narrow-pulse power discharge is used to study the synergistic control of mercury and dioxins,in which 1,2,4-trichlorobenzene(TCB)was used as a dioxin analog,by using a selfdesigned experimental system.Th... In this paper,narrow-pulse power discharge is used to study the synergistic control of mercury and dioxins,in which 1,2,4-trichlorobenzene(TCB)was used as a dioxin analog,by using a selfdesigned experimental system.The competitive effects of NO,SO2 and HC1 on the TCB removal by non-thermal plasma are discussed.The influence of acid gas on TCB degradation is reflected in the competitive effect.NO has the greatest influence on TCB degradation efficiency.The oxidation efficiency of Hg°decreased by about 10%in all three acidic gas atmospheres,and the effect of each gas component on Hg()oxidation is complex.In the flue gas atmosphere of'acid gas+Hg°+TCB',the mechanism of the synergistic control of Hg°and TCB by the nonthermal plasma is different,which has competition and promotion relationship between each other.The contribution of various flue gas components to the results was complicated,but the overall experimental results show that the synergistic control effect of the system can continue to improve.According to the generated product backstepping,-OH plays an important role in the synergistic control of the degradation of Hg°and TCB.Through this study,we hope to provide basic research data for the collaborative control of flue gas in the incineration industry. 展开更多
关键词 NARROW pulse discharge SYNERGISTIC CONTROL TCB degradation Hg°oxidation
E-beam generation in discharges initiated by voltage pulses with a rise time of 200 ns at an air pressure of 12.5-100 kPa
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作者 Victor TARASENKO Dmitry BELOPLOTOV +1 位作者 Mikhail LOMAEV Dmitry SOROKIN 《等离子体科学与技术:英文版》 SCIE EI CAS CSCD 2019年第4期52-60,共9页
The effect of air pressure(12.5,25,50,and 100 kPa)on the gen eration of runaway electron beams in a non-uniform electric field when applying voltage pulses(~35 kV)with a rise time of?200 ns has been studied.The result... The effect of air pressure(12.5,25,50,and 100 kPa)on the gen eration of runaway electron beams in a non-uniform electric field when applying voltage pulses(~35 kV)with a rise time of?200 ns has been studied.The results show that the discharge has various stages:streamer,diffuse,and spark.Initially,a wide streamer develops in the gap and a diffuse discharge is formed.A spark is formed u 100 ns after the breakdown.The current pulse of a supershort avalanche electron beam(SAEB)was measured with a collector at various pressures of air.Experiments show that there are two modes of generation of run away electrons.At an air pressure of 25-100 kPa,a single SAEB current pulse with a full width at half-maximum(FWHM)of 120-140 ps is observed.At the air pressure of 12.5 kPa,two current pulses of the electron beam are observed.FWHM of the first and second current pulses are ul40ps and u300 ps,respectively.The current pulse amplitude of the second electron beam is higher than that of the first one,but the electron energy is less. 展开更多
关键词 DIFFUSE discharge RUNAWAY ELECTRONS STREAMER BREAKDOWN displacement current
Evolution model of a modern delta fed by a seasonal river in Daihai Lake,North China:determined from groundpenetrating radar and trenches
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作者 Beibei LIU Chengpeng TAN +2 位作者 Xinghe YU Xin SHAN Shunli LI 《地球科学前沿:英文版》 SCIE CAS CSCD 2019年第2期262-276,共15页
While deltas fed by seasonal rivers are common in modem sedimentary environments,their characteristics remain unclear as compared to those fed by perennial rivers.This study identifies a small delta discharged by a se... While deltas fed by seasonal rivers are common in modem sedimentary environments,their characteristics remain unclear as compared to those fed by perennial rivers.This study identifies a small delta discharged by a seasonal stream flowing into Daihai Lake,in northern China,which is driven by ephemeral and high-energy flood events.Detailed 3D facies architecture was analyzed using ground-penetrating radar (GPR) and sedimentary logs from outcrop and trenches.Four types of radar surfaces,including truncations of underlying inclined strata,weak reflections,and depositional surface of downlap and onlap,were identified.Six radar facies (highangle obliquetangential,low-angle subparallel,gently plane parallel,plane-parallel,chaotic,and continuous strong reflection) were identified based on distinctive reflections,including amplitude,continuity,dip,and termination patterns.Five depositional units (Unit A to E) were documented from proximal to distal delta.Seasonal discharge signatures include significant grain-size decrease over short distance,abundant Froude supercritical flow sedimentary structures,poorly developed barforms,and small-scale scour and fill structures.Records of lake-level and sediment budget were evaluated over the past 60 years.In highstand stage (1960- 1980),amalgamated channel (Units A and B),and delta front (Unit C) were deposited.In slope stage (1980-1996),the lower deposits (Units A,B,C) were eroded by Unit D with a distinct truncation surface.In lowstand stage,most eroded sediments bypassed the incised channel and accumulated in the distal part,in which a new depositional unit was formed (Unit E).The model demonstrates that deltas fed by seasonal rivers tend to accumulate large amounts of sediments carried by high magnitude floods within short periods. 展开更多
关键词 DELTA EVOLUTION SEASONAL discharge ground-penetrating radar SEDIMENTARY architecture Daihai Lake
Enhanced recovery after surgery protocol enhances early postoperative recovery after pancreaticoduodenectomy 预览
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作者 Ramasamy Mahendran Mallika Tewari +1 位作者 Vinod Kumar Dixit Hari Shankar Shukla 《国际肝胆胰疾病杂志:英文版》 SCIE CAS CSCD 2019年第2期188-193,共6页
Background:Enhanced recovery after surgery(ERAS)protocol is a multimodal,multidisciplinary and evidence-based approach to reduce surgical stress and enhance recovery in the postoperative period.This study aimed to ana... Background:Enhanced recovery after surgery(ERAS)protocol is a multimodal,multidisciplinary and evidence-based approach to reduce surgical stress and enhance recovery in the postoperative period.This study aimed to analyze the outcome of ERAS protocol in patients after pancreaticoduodenectomy(PD).Methods:A total of 50 consecutive patients with pancreatic/periampullary cancer who underwent PD between January 2016 to August 2017 were included in the study.As per the institute ERAS protocol,nasogastric tube(NGT)was removed on postoperative day(POD)1 if output was less than 200 mL and oral sips were allowed;oral liquids were allowed on POD2;semisolid diet by POD3;abdominal drain was removed on POD 4 if output was less than 100 mL with no evidence of postoperative pancreatic fistula(POPF);normal diet was allowed on POD5.Discharge criteria on POD6 were afebrile,tolerating oral normal diet,pain free and no surgery related complications(defined as per the ISGPS definitions).Results:NGT was removed on POD1 in 45(90%)patients,abdominal drain removed by POD4 in 41(82%)and 43(86%)patients were discharged on POD6.There was no 30-day postoperative mortality.Three(6%)patients had delayed gastric emptying(DGE).None had postoperative hemorrhage and POPF.Readmission rate was 8%.A significant relation was found between the length of hospital stay(LOS)with age(P<0.05)and a marginal relation between LOS and postoperative albumin(P=0.05).Conclusions:ERAS protocol can be safely followed in the perioperative care of patients who undergo PD.Early removal of NGT and allowing oral diet restore bowel function early.ERAS decreases the LOS and postoperative complications. 展开更多
关键词 Enhanced RECOVERY PROTOCOL PANCREATIC CANCER Periampullary CANCER PANCREATICODUODENECTOMY Early DISCHARGE
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Silicone-coated polyimide films deposited by surface dielectric barrier discharges
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作者 Junggil KIM Yunjung KIM +1 位作者 Sangjin KIM Guangsup CHO 《等离子体科学与技术:英文版》 SCIE EI CAS CSCD 2019年第1期93-99,共7页
Hybrid dielectric barrier discharges are investigated for plasma generated on the surface of a dielectric layer, where two conducting electrodes of high voltage and ground are formulated on the upper and bottom surfac... Hybrid dielectric barrier discharges are investigated for plasma generated on the surface of a dielectric layer, where two conducting electrodes of high voltage and ground are formulated on the upper and bottom surfaces. Using a flexible thin polyimide-film of a thickness ranging from 25 to 125 μm, a plasma is generated with a voltage of about 1 kV and a frequency of 40 kHz.However, the surface of the dielectric layer was etched through a chemical reaction involving plasma oxygen radical species, and thus the polyimide films failed readily, resulting in dielectric breakdown within short operating time ranging from a few minutes to several tens of minutes,based on the film thicknesses of 25 μm and 125 μm, respectively. These plasma erosions were prevented by coating the polyimide surface with a 25 μm thick silicone paste. The siliconecoated film surface was then reinforced remarkably against plasma erosion as the organic polymer was vulnerable to chemical reaction of the plasma species, while the inorganic silicone exhibited a high chemical resistance against plasma erosion. 展开更多
关键词 PLASMA DISCHARGE atmospheric pressure nonthermal PLASMA POLYIMIDE film PLASMA EROSION
A comparison of emissive and cold floating probe techniques for electric potential measurements in rf inductive discharge
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作者 Yaroslav MURZAEV Gen nadii LIZIAKIN +2 位作者 An drey GAVRIKOV Rinat TIMIRKHANOV Valentin SMIRNOV 《等离子体科学与技术:英文版》 SCIE EI CAS CSCD 2019年第4期94-98,共5页
A cold floating probe method was compared with the emissive floating probe method in terms of a low-pressure radio-frequency inductive discharge.The dependences of difference between the plasma potential and the float... A cold floating probe method was compared with the emissive floating probe method in terms of a low-pressure radio-frequency inductive discharge.The dependences of difference between the plasma potential and the floating potential on the electron temperature 1-8 eV,plasma density 109-1012 cm 3 and magnetic field 100-650 G were obtained.It was demonstrated that the difference between the potentials that obtained by these two methods can differ significantly from the expected value of 5.2 kTe/e for argon. 展开更多
关键词 emissive PROBE FLOATING PROBE rf INDUCTIVE DISCHARGE PLASMA potential measurement
渤海油田普通稠油冷采测试工艺 预览
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作者 高科超 高飞 +2 位作者 杨子 杨歧年 刘宝坤 《油气井测试》 2019年第1期38-45,共8页
针对渤海油田稠油井测试过程中存在的出砂、垂直管流黏阻大流动困难、PVT取样成功率低、计量误差大等难题,从射孔、防砂、控温、取样及计量工艺优化等方面细化研究,形成了由稳岩控砂射孔诱喷技术、井下测试管柱控温技术、稠油PVT取样技... 针对渤海油田稠油井测试过程中存在的出砂、垂直管流黏阻大流动困难、PVT取样成功率低、计量误差大等难题,从射孔、防砂、控温、取样及计量工艺优化等方面细化研究,形成了由稳岩控砂射孔诱喷技术、井下测试管柱控温技术、稠油PVT取样技术和稠油测试配套计量技术组成的普通稠油井冷采测试工艺。该工艺采用大孔径、深穿透、高密度射孔技术配合合适的诱喷压差提高油层渗流能力,联合井筒保温和加热技术降低原油在井筒中的流动阻力,优化取样器放置位置和取样时机,采用具有压力补偿功能的单相取样器保证取样准确性,配备可加热式的25m^3计量罐实现精确计量。渤海油田蓬莱31-X1井现场应用表明,取样压差仅为0.925MPa,取样合格;采用螺杆泵排液求产,80r/min时日产油52.84m^3,130r/min时日产油89.28m^3;四次开关井均取得了合格的压力数据资料。该工艺为类似稠油油田产能释放及有效动用提供了技术支撑。 展开更多
关键词 渤海油田 普通稠油 试采 射孔 控温 取样 计量 排液
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