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Separation of Ions from Volatile Organic Compounds Using High-Field Asymmetric Waveform Ion Mobility Spectrometry-Mass Spectrometer 被引量:2
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作者 李华 王晓浩 +2 位作者 唐飞 杨吉 丁力 《Chinese Journal of Chemical Physics》 SCIE CAS CSCD 2010年第2期125-132,I0001,共9页
A combination of high-field asymmetric waveform ion mobility spectrometry (FAIMS) with mass spectrometer (MS) was analyzed. FAIMS separates ions from the volatile organic compounds in the gas-phase as an ion-filte... A combination of high-field asymmetric waveform ion mobility spectrometry (FAIMS) with mass spectrometer (MS) was analyzed. FAIMS separates ions from the volatile organic compounds in the gas-phase as an ion-filter for MS. The sample ions were created at ambient pressure by ion source, which was equipped with a 10.6 eV UV discharge lamp (A=116.5 nm). The drift tube of FAIMS is composed of two parallel planar electrodes and the dimension is 10 mm×8 mm×0.5 mm. FAIMS was investigated when driven by the high-filed rectangular asymmetric waveform with the peak-to-peak voltage of 1.36 kV at the frequency of 1 MHz and the duty cycle of 30%. The acetone, the butanone, and their mixture were adopted to characterize the FAIMS-MS. The mass spectra obtained from MS illustrate that there are ion-molecular reactions between the ions and the sample neutral molecular. And the proton transfer behavior in the mixture of the acetone and the butanone is also observed. With the compensation voltage tuned from -30 V to 10 V with a step size of 0.1 V, the ion pre-separation before MS is realized. 展开更多
关键词 high-field asymmetric waveform ion mobility spectrometry Mass spectrometer Ion-filter Ion-molecular reaction Proton transfer
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Electric-magnetic-force characteristics of rare earth barium copper oxide superconductor high-field coils based on screening effect and strain sensitivity 被引量:3
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作者 Wenhai ZHOU Youhe ZHOU 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI CSCD 2022年第8期1249-1268,共20页
Rare earth barium copper oxide(REBCO)is the most researched and commercialized second-generation high-temperature superconducting material.Due to the anisotropic structure,strong deformation sensitivity,and central fi... Rare earth barium copper oxide(REBCO)is the most researched and commercialized second-generation high-temperature superconducting material.Due to the anisotropic structure,strong deformation sensitivity,and central field errors caused by screening current effects,it is still a challenge for commercialization applications.In this study,the transversely isotropic constitutive relationship is selected as the mechanical model based on the structural characteristics of REBCO tapes,and suitable microelements are selected to equate the elastic constants using their average stress-strain relationships.Then,a two-dimensional axisymmetric model for coils wound by single-layer tapes is constructed to analyze the dependence of the electric-magnetic-force distribution in the tape on the strain.Finally,the anisotropic approximation of the homogenized bulk method is used to equate large-turn high-field coils,and the electric-magnetic-force distribution characteristics of the coils with/without screening effects and mechanical strain conditions are investigated,respectively.The results reveal that the mechanical strain has a weakening effect on the electromagnetic field distribution of superconducting tapes,but causes a significant enhancement in the force field distribution.In the presence of 0.5% mechanical strain,the maximum weakening of the peak value of the current density and the critical current density inside the high-field coil can reach about 8% and 13%,respectively,with a nearly 5 times increase in the peak stress.The screening current makes the current field distribution inside the coil improve by about 10 times.The screening current induced magnetic field can reach up to 0.8 T,making the relative error of the high-field coil center up to 7.8%. 展开更多
关键词 screening current strain sensitivity mechanical behavior rare earth barium copper oxide(REBCO)high-field coil electromagnetic field distribution
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Negligible oxygen vacancies,low critical current density,electric-field modulation,in-plane anisotropic and high-field transport of a superconducting Nd_(0.8)Sr_(0.2)NiO_(2)/SrTiO_(3) heterostructure 被引量:2
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作者 Xiao-Rong Zhou Ze-Xin Feng +9 位作者 Pei-Xin Qin Han Yan Xiao-Ning Wang Pan Nie Hao-Jiang Wu Xin Zhang Hong-Yu Chen Zi-Ang Meng Zeng-Wei Zhu Zhi-Qi Liu 《Rare Metals》 SCIE EI CAS CSCD 2021年第10期2847-2854,共8页
The emerging Ni-based superconducting oxide thin films are rather intriguing to the entire condensed matter physics. Here, we report some brief experimental results on transport measurements for a 14-nm-thick supercon... The emerging Ni-based superconducting oxide thin films are rather intriguing to the entire condensed matter physics. Here, we report some brief experimental results on transport measurements for a 14-nm-thick superconducting Nd_(0.8)Sr_(0.2)NiO_(2)/SrTiO_(3) thin-film heterostructure with an onset transition temperature of~9.5 K. Photoluminescence measurements reveal that there is negligible oxygen vacancy creation in the SrTiO_(3) substrate during thin-film deposition and post chemical reduction for the Nd_(0.8)Sr_(0.2)NiO_(2)/SrTiO_(3) heterostructure. It was found that the critical current density of the Nd_(0.8)Sr_(0.2)NiO_(2)/SrTiO_(3) thin-film heterostructure is relatively small, ~4×10^(3) A·cm^(-2). Although the surface steps of SrTiO_(3) substrates lead to an anisotropy for in-plane resistivity, the superconducting transition temperatures are almost the same. The out-of-plane magnetotransport measurements yield an upper critical field of~11.4 T and an estimated in-plane Ginzburg–Landau coherence length of~5.4 nm. High-field magnetotransport measurements up to 50 T reveal anisotropic critical fields at 1.8 K for three different measurement geometries and a complicated Hall effect. An electric field applied via the SrTiO_(3) substrate slightly varies the superconducting transition temperature. These experimental results could be useful for this rapidly developing field. 展开更多
关键词 NICKELATES SUPERCONDUCTIVITY Ni-based superconductivity high-field transport Electric-field modulation
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High-Field MRI Contribution in Tolosa-Hunt Syndrome (THS). Report of Two Cases and Review of Literature 被引量:2
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作者 Chérif Mohamadou Aidara Philomène Kouna +6 位作者 Jennifer Nyangui Mapaga Nfally Badji Hamidou Deme Abdoulaye Dione Diop Abdoulaye Ndoye Diop Sokhna Ba El Hadj Niang 《Open Journal of Radiology》 2018年第3期141-149,共9页
Background: Tolosa Hunt Syndrome is an inflammatory condition of unknown etiology of the cavernous sinus and superior orbital fissure. Because of the difficulty in establishing histological evidence, his diagnosis is ... Background: Tolosa Hunt Syndrome is an inflammatory condition of unknown etiology of the cavernous sinus and superior orbital fissure. Because of the difficulty in establishing histological evidence, his diagnosis is based on a set of arguments established by the International Headache Society. MRI allows indirect visualization of the granuloma and plays a key role in diagnosis and follow-up. Aim: To illustrate High-field MRI contribution in Tolosa-Hunt Syndrome (THS). Cases Presentation: Two patients, a 25-year-old female and a 40-year-old male were recruited in this retrospective case report study at the Radiology service of Fann University Hospital (Dakar Senegal). The first patient has been suffering from a right retro-orbital pain and diplopia for 2 months and the second from a painful oculomotor nerve palsy for 3 months. Blood tests, lumbar puncture, thyroid hormone levels and an infectious screen were done. Screening for converting enzymes, and serum antibodies were also done. They underwent a high field MRI (Siemens 1.5T) with T1, T2, FLAIR, T2*, diffusion B1000, TOF polygon, CISS 3D and T1 gadolinium sequences in the 3 planes space. No significant abnormality was detected in blood tests or CSF analysis. Screening for converting enzymes and serum antibodies screen were also negative. For each patient, MRI examinations showed a non tumoral thickening of the right cavernous sinus, suggesting a granulomatous involvement. Tolosa Hunt Syndrome was evoked firstly. They were put on corticotherapy at high doses with a spectacular regression of symptoms. The Criteria of the International Headache Society of THS were met in both patients. Conclusion: High-field MRI is a significant diagnostic tool in the assessment of painful ophthalmoplegia. It allows a direct visualization of the granuloma of the cavernous sinus and assesses its course throughout the disease. 展开更多
关键词 PAINFUL OPHTHALMOPLEGIA Tolosa-Hunt Syndrome Criterias of International HEADACHE SOCIETY high-field MRI
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High Density Plasma Heating by EC-Waves Injected from the High-Field Side for Mode Conversion to Electron Bernstein Waves in LHD
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作者 Y.YOSHIMURA S.KUBO +8 位作者 T.SHIMOZUMA H.IGAMI H.TAKAHASHI M.NISHIURA S.OGASAWARA R.MAKINO T.MUTOH H.YAMADA A.KOMORI 《Plasma Science and Technology》 SCIE EI CAS CSCD 2013年第2期93-96,共4页
To realize an excitation of electron Bernstein waves (EBW) via mode conversion from X-mode waves injected from the high magnetic field side (HFS), new inner-vessel mirrors were installed close to a helicM coil in ... To realize an excitation of electron Bernstein waves (EBW) via mode conversion from X-mode waves injected from the high magnetic field side (HFS), new inner-vessel mirrors were installed close to a helicM coil in the large helicM device (LHD). 77 GHz electron cyclotron (EC) wave beams injected from an existing EC-wave injection system toward the new mirror are reflected on the mirror so that the beams are injected to plasmas from HFS. Evident increases in the electron temperature at the plasma core region and the plasma stored energy were observed by the HFS beam injection to the plasmas with the line-average electron density of 7.5~ 1019 m-3, which is slightly higher than the plasma cut-off density of 77 GHz EC-waves, 7.35~ 1019 m-3. The heating efficiency evaluated from the changes in the time derivative of the plasma stored energy reached ,,~70%. Although so far it is not clear which is the main cause of the heating effect, the mode-converted EBW or the X-mode wave itself injected from the HFS, an effective heating of high-density plasma over the plasma cut-off of EC-wave was successfully demonstrated. 展开更多
关键词 electron Bernstein wave EBW slow X-B overdense high density plasmaheating high-field side injection ECH LHD
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Laser-assisted Stark deceleration of CaF in its rovibronic ground (high-field-seeking) state
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作者 Yuefeng Gu Kai Chen +1 位作者 Yunxia Huang Xiaohua Yang 《Chinese Physics B》 SCIE EI CAS CSCD 2019年第4期170-176,共7页
A near-resonant, red-detuning laser-assisted Stark deceleration scheme is proposed to slow CaF in its high-fieldseeking rovibronic ground state. The assisting Gaussian laser beam can confine CaF molecules transversely... A near-resonant, red-detuning laser-assisted Stark deceleration scheme is proposed to slow CaF in its high-fieldseeking rovibronic ground state. The assisting Gaussian laser beam can confine CaF molecules transversely owing to the optical Stark effect. Simulations suggest that the present scheme is superior to previous Stark decelerators. Under typical experimental conditions, when the assisting laser frequency is red-detuned to the molecular transition(λ~606.3 nm) by5.0 GHz and the laser power is about 5.6 W, the proposed decelerator can achieve a total number at the order of 10~4 CaF molecules with a number density at the order of 10~8 cm^(-3). The equivalent temperature of the obtained cold CaF molecules is 2.3 mK. Additionally, the desired assisting laser power can be as low as about 1.2 W if keeping the red-detuning value to be 1.0 GHz, which further suggests its experimental feasibility. 展开更多
关键词 STARK DECELERATION polar molecule optical STARK effect high-field-seeking STATE
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Fast Growth of Highly Ordered TiO2 Nanotube Arrays on Si Substrate under High-Field Anodization 被引量:1
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作者 Jingnan Song Maojun Zheng +7 位作者 Bin Zhang Qiang Li Faze Wang Liguo Ma Yanbo Li Changqing Zhu Li Ma Wenzhong Shen 《Nano-Micro Letters》 SCIE EI CAS 2017年第2期3-13,共11页
Highly ordered TiO_2 nanotube arrays(NTAs) on Si substrate possess broad applications due to its high surfaceto-volume ratio and novel functionalities, however, there are still some challenges on facile synthesis. Her... Highly ordered TiO_2 nanotube arrays(NTAs) on Si substrate possess broad applications due to its high surfaceto-volume ratio and novel functionalities, however, there are still some challenges on facile synthesis. Here, we report a simple and cost-effective high-field(90–180V) anodization method to grow highly ordered TiO_2 NTAs on Si substrate,and investigate the effect of anodization time, voltage, and fluoride content on the formation of TiO_2 NTAs. The current density–time curves, recorded during anodization processes, can be used to determine the optimum anodization time. It is found that the growth rate of TiO_2 NTAs is improved significantly under high field, which is nearly 8 times faster than that under low fields(40–60 V). The length and growth rate of the nanotubes are further increased with the increase of fluoride content in the electrolyte. 展开更多
关键词 TiO2 nanotube arrays Si substrate Anodization High field Controllable preparation
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High-field-induced electron detrapping in an AlGaN/GaN high electron mobility transistor 被引量:4
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作者 付立华 陆海 +4 位作者 陈敦军 张荣 郑有炓 魏珂 刘新宇 《Chinese Physics B》 SCIE EI CAS CSCD 2012年第10期512-515,共4页
A step stress test is carried out to study the reliability characteristics of an AlGaN/GaN high electron mobility transistor(HEMT).An anomalous critical drain-to-gate voltage with a negative temperature coefficient ... A step stress test is carried out to study the reliability characteristics of an AlGaN/GaN high electron mobility transistor(HEMT).An anomalous critical drain-to-gate voltage with a negative temperature coefficient is observed in the stress sequence,beyond which the HEMT device starts to recover from degradation induced by early lower voltage stress.While the performance degradation featuring the drain current slump stems from electron trapping in the surface or bulk states during low-to-medium bias stress,the recovery is attributed to high field induced electron detrapping.The carrier detrapping mechanism could be helpful for lessening the trapping-related performance degradation of a GaN-based HEMT. 展开更多
关键词 AlGaN/GaN HEMT step stress test high electric field electron detrapping
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High-Field-Strength Elements in Mafic Volcanics from North China Craton: Implications for Archean-Proterozoic Boundary and Source Composition 被引量:1
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作者 Liu Yongsheng Gao Shan Luo Tingchuan Faculty of Earth Sciences, China University of Geosciences, Wuhan 430074 《Journal of Earth Science》 SCIE CAS CSCD 1998年第2期17-23,共7页
Archean to Cenozoic mafic volcanic rocks from the North China craton are studied. They show Archean Proterozoic (Ar Pt) boundary and geochemical anomalies in Cenozoic basalts. Proterozoic mafic volcanics are enriche... Archean to Cenozoic mafic volcanic rocks from the North China craton are studied. They show Archean Proterozoic (Ar Pt) boundary and geochemical anomalies in Cenozoic basalts. Proterozoic mafic volcanics are enriched in most of the high field strength elements (HFSE) compared with Archean ones. Nb, Ta and Th show a distinct sequence of incompatibility in Archean and Proterozoic. The Cenozoic basalts are enriched in HFSE and Ni and their REEs are strongly differentiated with positive Eu anomalies ( δ (Eu)=1.14). The Ar Pt boundary could be related to change in oxygen fugacity and requires an increasing importance of enriched mantle source. The geochemistry of Cenozoic basalts implies a mantle source similar to OIB. Residuum from subducting partial melting of old basaltic oceanic crust and continental crust is likely to contribute to the formation of the enriched mantle. 展开更多
关键词 mafic volcanic rocks high field strength element Archean Proterozoic boundary enriched mantle.
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Ultra-high-field magnetic resonance:Why and when? 被引量:1
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作者 Ewald Moser 《World Journal of Radiology》 CAS 2010年第1期37-40,共4页
This paper briefly summarizes the development of magnetic resonance imaging and spectroscopy in medicine.Aspects of magnetic resonancephysics and-technology relevant at ultra-high magnetic fields as well as current li... This paper briefly summarizes the development of magnetic resonance imaging and spectroscopy in medicine.Aspects of magnetic resonancephysics and-technology relevant at ultra-high magnetic fields as well as current limitations are highlighted.Based on the first promising studies,potential clinical applications at 7 Tesla are suggested.Other aims are to stimulate awareness of the potential of ultra-high field magnetic resonance and to stimulate active participation in much needed basic or clinical research at 7 Tesla or higher. 展开更多
关键词 Alzheimer’s disease Brain tumors CARTILAGE Functional MAGNETIC RESONANCE imaging MAGNETIC RESONANCE MAGNETIC RESONANCE spectroscopy Multiple SCLEROSIS Ultra-high field MAGNETIC RESONANCE methods
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Mechanical failure:A critical bottleneck for high-field high-temperature superconducting magnets
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作者 Peifeng Gao Yoshinori Yanagisawa 《Superconductivity》 2026年第1期58-61,共4页
The pursuit of ultrahigh-field high-temperature superconducting(HTS)magnets faces a significant challenge:mechanical failure is a primary fundamental limiter of progress.In extreme cryogenic electromechanical environm... The pursuit of ultrahigh-field high-temperature superconducting(HTS)magnets faces a significant challenge:mechanical failure is a primary fundamental limiter of progress.In extreme cryogenic electromechanical environments,coupled multimode failures—namely interfacial delamination,intralayer fracture,substrate yielding,and buckling—form the critical bottleneck.These failure modes are intrinsically coupled:Lorentz forces generate destructive hoop stresses,thermal expansion coefficient mismatches induce radial interface-decoupling tensions,multiaxial stress states accelerate crack propagation,and cyclic loads cause irreversible performance degradation.Such mechanical failures typically precede quench events.The resolution of these issues demands convergent innovation integrating material-centric strategies,structural intelligence,and operational resilience.Overcoming this mechanical barrier is pivotal for incremental field gains and unleashing the transformative potential of HTS magnets in fusion energy,next-generation nuclear magnetic resonance,and compact medical devices.A cross-disciplinary paradigm fusing materials science,solid mechanics,and intelligent engineering is necessary to transcend this frontier. 展开更多
关键词 high-field HTS magnets Mechanical failure Extreme multiphysics conditions
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转臂式高速离心机减阻设计及机室流场特性研究
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作者 陈红永 杨鑫 +4 位作者 黎启胜 龚志斌 宋琼 李心耀 尹益辉 《应用力学学报》 北大核心 2026年第1期164-170,共7页
风阻功率是大型转臂式土工离心机驱动功率设计的重要依据,机室流场具有随流、温升、流速高等特点。为降低风阻需对转臂或吊篮采取整流减阻设计。针对两型分别采用转臂整流和整流罩减阻的离心机,开展了基于CFD(computational fluid dynam... 风阻功率是大型转臂式土工离心机驱动功率设计的重要依据,机室流场具有随流、温升、流速高等特点。为降低风阻需对转臂或吊篮采取整流减阻设计。针对两型分别采用转臂整流和整流罩减阻的离心机,开展了基于CFD(computational fluid dynamics)的气动特性仿真,通过优化仿真参数获得离心机高速运行时的机室内部流场流场特性及离心机风阻功率,并通过型线设计对离心机整流罩进行了气动阻力系数优化。研究表明:高速离心机低气压运行时机室下壁面的摩擦阻力矩占主导,高于周向壁面的摩擦阻力矩;吊篮不采用整流罩时,在迎风端面肩部出现了流动分离,压差阻力较大;采用整流罩后,吊篮前缘肩部的分离被削弱,总阻力系数大幅降低。研究表明对于高速离心机开展整流设计是必要的,通过转臂外形设计及整流罩设计,可有效降低风阻功率,更有益于控制机室温升。 展开更多
关键词 转臂式离心机 高速转动 流场 CFD 整流罩
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海拔3500米水轮发电机定子线圈及绕组防电晕系统研究
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作者 冯超 杨光东 +3 位作者 黄程伟 刘豫川 陈阳 青晔 《科学技术创新》 2026年第8期220-224,共5页
本研究针对海拔3500米高海拔环境下水轮发电机定子线圈的防电晕设计进行了系统研究。考虑到气压降低对电场分布和绝缘性能的影响,采用COMSOL进行电场仿真分析,探讨了单一防电晕设计方案的电场分布、电位梯度以及电晕放电风险。试验部分... 本研究针对海拔3500米高海拔环境下水轮发电机定子线圈的防电晕设计进行了系统研究。考虑到气压降低对电场分布和绝缘性能的影响,采用COMSOL进行电场仿真分析,探讨了单一防电晕设计方案的电场分布、电位梯度以及电晕放电风险。试验部分通过人工气候实验室模拟高海拔环境,对该设计方案的性能进行了验证。研究结果表明,高海拔防电晕设计方案在电场均匀性和电晕放电抑制方面具有显著优势。本文通过理论分析、仿真计算和实验验证,提出了适用于高海拔环境的最优设计方案,为水轮发电机定子线圈防电晕技术提供了重要参考。 展开更多
关键词 水轮发电机 定子线圈 防电晕设计 高海拔 电场仿真 人工气候试验
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高含盐气田采出水不纯化电解制氢先导试验研究
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作者 徐文龙 陆红军 +4 位作者 何战友 周子健 孙支林 姬伟 王百 《油气田地面工程》 2026年第3期35-41,共7页
长庆油田、气田采出水产水量大、水质复杂,具有含高盐、高悬浮物、高COD的特征,以处理后回注地层为主,存在处理成本高、水资源浪费情况。国内外现有主流电解制氢技术普遍依赖纯水配置电解液,如果将气田采出水处理成纯水后制氢,则会大幅... 长庆油田、气田采出水产水量大、水质复杂,具有含高盐、高悬浮物、高COD的特征,以处理后回注地层为主,存在处理成本高、水资源浪费情况。国内外现有主流电解制氢技术普遍依赖纯水配置电解液,如果将气田采出水处理成纯水后制氢,则会大幅增加采出水处理站建设投资和运维成本。鉴于此,长庆油田借鉴“海水无淡化原位直接电解制氢海试”成功经验,选取了苏里格、靖边、榆林3大气田10种不同类型采出水,先后开展室内膜耐受性实验+处理补水实验和不纯化电解制氢先导试验,发现采出水中表活剂等COD组分会对疏水多孔膜材料产生改性作用,从而破坏膜的结构,影响电解液的纯度。通过简易预处理+疏水膜蒸汽渗透方式,实现了“采出水侧”向“电解液侧”的补给。利用0.4 m^(3)/h(0℃,1 atm)电解制氢设备,开展了5类含不同TDS和COD含量的采出水电解制氢试验,累计制氢时长385 h,制氢纯度99.999%,验证了高含盐气田采出水不纯化电解制氢的技术可行性。 展开更多
关键词 气田采出水 高含盐 不纯化 电解制氢
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中原油田成熟油气区提产提效工程技术新进展与展望
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作者 王飞 张文昌 +2 位作者 徐海民 李玉娜 黄鹂 《石油钻探技术》 北大核心 2026年第1期23-32,共10页
为破解中原油田后备油气资源劣质化、井下工况复杂化等方面的技术难题,支撑油田持续稳产上产,以东濮老区、普光高含硫气田、内蒙古探区三大成熟油气生产基地为研究对象,系统梳理了近年来复杂断块油藏提质增效、超深高含硫气田中后期稳... 为破解中原油田后备油气资源劣质化、井下工况复杂化等方面的技术难题,支撑油田持续稳产上产,以东濮老区、普光高含硫气田、内蒙古探区三大成熟油气生产基地为研究对象,系统梳理了近年来复杂断块油藏提质增效、超深高含硫气田中后期稳产、内蒙古地质地表双复杂油藏增储上产系列工程技术。东濮老区集成应用剩余油精细描述、老井侧钻、差异化压裂及提高采收率等技术,原油产量连续5年上涨,盈亏平衡点持续下降;普光高含硫气田通过攻关储层精细表征、精准调整挖潜、硫沉积治理及湿气增压等技术,实现连续16年稳产高产;内蒙古探区通过突破复杂油藏评价建产、稠油CO_(2)复合冷采及低成本地面工艺技术,年产量增幅达70%。实践表明,针对性的工程技术创新是支撑成熟油气区稳产增产的关键。建议今后持续完善东濮复杂断块精益开发、升级高含硫气田全产业链安全高效开发、突破内蒙古低丰度油气藏效益开发三大工程技术体系,为国内同类型油气藏效益开发提供工程技术支撑。 展开更多
关键词 中原油田 工程技术 提产提效 东濮老区 普光高含硫气田 内蒙古探区
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电热耦合条件下薄膜电容器的电介质分子结构设计与新材料研制
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作者 王乾 周颖 +5 位作者 高岩峰 卢毅 邓靖宇 刘瑛岩 梁曦东 仵超 《中国电机工程学报》 北大核心 2026年第1期409-423,I0031,共16页
聚合物电介质是薄膜电容器的核心,耐电热耦合严酷条件的高性能电介质薄膜材料是提高薄膜电容器性能的关键。目前的商用聚合物薄膜材料无法兼顾高温和强电场条件下的应用需求。该文介绍一种基于有目标的分子结构设计的聚合物电介质新材... 聚合物电介质是薄膜电容器的核心,耐电热耦合严酷条件的高性能电介质薄膜材料是提高薄膜电容器性能的关键。目前的商用聚合物薄膜材料无法兼顾高温和强电场条件下的应用需求。该文介绍一种基于有目标的分子结构设计的聚合物电介质新材料研究方法。通过对大量典型聚合物电气性能的试验、仿真计算与机理分析,提出能够同时耐高温和强电场的聚合物电介质关键设计指标与分子结构特征,以此为基础设计新的分子结构,研制聚降冰片烯系列薄膜新材料,其电热耦合严酷条件下(>150℃,>700 MV/m)的性能优异。对分子结构中主链以及侧链的功能性基团进行调控,还能进一步提升储能密度。基于分子结构设计的高性能电介质新材料研究方法提出多目标约束下电介质材料研究的新范式,摆脱了传统的依靠尝试-验证进行新材料研究的模式。 展开更多
关键词 电介质 聚合物 分子结构 电容器 强电场 高温
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基于视觉传感器的大田甘蓝对靶变量喷雾系统设计与试验
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作者 罗亚辉 李文 +5 位作者 蒋蘋 胡文武 孙超然 齐澳林 石毅新 庄腾飞 《农业机械学报》 北大核心 2026年第2期46-57,共12页
为改善甘蓝等高密度田间作物的机械化病虫害防治效果,解决传统的大田高地隙喷雾机农药用量大、作业效率低及存在的药液浪费等问题,本研究结合大田甘蓝的农艺特性,设计了一套基于视觉传感器识别的高地隙变量施药系统。利用Gemini 335型... 为改善甘蓝等高密度田间作物的机械化病虫害防治效果,解决传统的大田高地隙喷雾机农药用量大、作业效率低及存在的药液浪费等问题,本研究结合大田甘蓝的农艺特性,设计了一套基于视觉传感器识别的高地隙变量施药系统。利用Gemini 335型深度相机实时探测作物靶标,并融合脉宽调制技术(Pulse Width Modulation,PWM)实现农药的精准对靶变量喷洒。提出一种改进YOLO v8n的目标检测模型,通过田间试验测试,其检测精确率可达90.2%,提高1.5个百分点;检测速度提高7.6 f/s,模型的检测精度得以改善,可满足甘蓝田间防治精度需求。设计电磁阀占空比的流量开闭测试模型,进行不同占空比测试,不同喷雾压力拟合决定系数R2均大于0.9,相关性显著。对整个系统集成并进行田间试验,变量喷雾模式,对靶变量喷洒的靶心雾滴沉积密度明显高于常量喷雾,平均雾滴密度增量为21.53个/cm2,甘蓝靶心区域覆盖率可达23.8%,且沉积均匀性高,变异系数仅0.4%。相比常量喷雾模式下,甘蓝表面整体覆盖率提升5.2个百分点,能够实现按需对靶变量施药且满足甘蓝的病虫害防治要求,整套系统作业性能稳定。研究结果可为高密度蔬菜等作物的田间管理与病虫害治理提供方法和思路,为高地隙精准施药防治技术植保应用提供参考。 展开更多
关键词 大田甘蓝 变量施药 高地隙喷雾机 脉宽调制 视觉传感器 改进YOLO v8n算法
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低磁场高效率同轴双模相对论切伦科夫振荡器
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作者 周文刚 邓如金 +2 位作者 张鹏 李家文 张珂嘉 《强激光与粒子束》 北大核心 2026年第2期43-48,共6页
为了提高高功率微波源在低导引磁场下的效率,提出了一种低磁场高效率同轴双模相对论切伦科夫振荡器。该器件工作在同轴准TEM模式与同轴TM_(01)模式下,利用双模工作机制,实现了低磁场下(<0.4 T)的高效率输出。在粒子模拟中,导引磁场0.... 为了提高高功率微波源在低导引磁场下的效率,提出了一种低磁场高效率同轴双模相对论切伦科夫振荡器。该器件工作在同轴准TEM模式与同轴TM_(01)模式下,利用双模工作机制,实现了低磁场下(<0.4 T)的高效率输出。在粒子模拟中,导引磁场0.35 T时,器件实现了功率3 GW的微波输出、束-波转换效率40%。同时,针对实验中遇到的射频击穿现象,通过增加慢波结构周期数量来提高功率容量,并通过仿真和实验进行验证。最终实验中在0.37 T磁场下,输出微波功率2.85 GW,脉宽57 ns,转换效率34%。在低磁场下获得的实验结果为高功率微波系统小型化的发展提供了强力支撑。 展开更多
关键词 高功率微波 低磁场 高效率 相对论切伦科夫振荡器 双模工作
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用于机器视觉的高分辨率双视场双远心镜头设计
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作者 叶承轩 陈子坤 +2 位作者 徐智谋 王双保 张学明 《光学技术》 北大核心 2026年第1期1-6,共6页
双远心镜头所具有的低畸变、大景深等优点,与机器视觉中高成像质量和多场景应用需求相匹配,利用Zemax仿真设计了一款可用于机器视觉的高分辨率双视场双远心镜头。将该双远心系统分为固定结构和可拆卸结构的两部分,通过翻转可拆卸结构,... 双远心镜头所具有的低畸变、大景深等优点,与机器视觉中高成像质量和多场景应用需求相匹配,利用Zemax仿真设计了一款可用于机器视觉的高分辨率双视场双远心镜头。将该双远心系统分为固定结构和可拆卸结构的两部分,通过翻转可拆卸结构,即可在保证高分辨率和高远心度的同时改变系统的光学放大率,提高了远心镜头在多个应用场景的适用性。所设计的具有双视场双远心镜头在可见光波段(486~656nm)内,平均弥散斑半径小于9μm,各视场远心度均小于0.015°,畸变率低于0.1%,调制传递函数在75lp/mm时大于0.4,各视场波像差均小于λ/4。性能能够满足实际应用要求。 展开更多
关键词 应用光学 双视场 高分辨率 双远心镜头 远心度 畸变
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安徽大学自由电子激光装置控制系统研发
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作者 陈帆 丁石川 +6 位作者 陈思跃 徐忠祥 王改 陶骏 潘天红 刘东洋 高颂 《核电子学与探测技术》 北大核心 2026年第3期379-387,共9页
安徽大学强光磁试验装置由一台红外自由电子激光装置与六个实验站组成,其中自由电子激光装置控制系统采用实验物理与工业控制系统(Experimental Physics and Industrial Control System,EPICS)作为开发框架。基于EPICS分布式控制架构,... 安徽大学强光磁试验装置由一台红外自由电子激光装置与六个实验站组成,其中自由电子激光装置控制系统采用实验物理与工业控制系统(Experimental Physics and Industrial Control System,EPICS)作为开发框架。基于EPICS分布式控制架构,对安徽大学自由电子激光装置各子系统控制进行了详细的设计研究。在控制系统网络部署方面,引入虚拟局域网(Virtual Local Area Network,VLAN)技术构建运行环境,显著提升了系统可靠性与部署效率。目前已完成开发的系统运行表明,该控制系统具有运行高效、稳定可靠等特点,其设计思路和实施方法可为同类控制系统的开发提供参考。 展开更多
关键词 强光磁试验装置 红外自由电子激光装置 控制系统 EPICS 虚拟局域网技术
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