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Analysis of Pulse Signals Based on Array Pulse Volume
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作者 CUI Ji TU Li-ping +3 位作者 ZHANG Jian-feng ZHANG Shao-liang ZHANG Zhi-feng XU Jia-tuo 《中国结合医学杂志:英文版》 SCIE CAS CSCD 2019年第2期103-107,共5页
Objective: To collect and analyze multi-dimensional pulse diagram features with the array sensor of a pressure profile system(PPS) and study the characteristic parameters of the new multi-dimensional pulse diagram by ... Objective: To collect and analyze multi-dimensional pulse diagram features with the array sensor of a pressure profile system(PPS) and study the characteristic parameters of the new multi-dimensional pulse diagram by pulse diagram analysis technology. Methods: The pulse signals at the Guan position of left wrist were acquired from 105 volunteers at the Shanghai University of Traditional Chinese Medicine. We obtained the pulse data using an array sensor with 3×4 channels. Three dimensional pulse diagrams were constructed for the validated pulse data, and the array pulse volume(APV) parameter was computed by a linear interpolation algorithm. The APV differences among normal pulse(NP), wiry pulse(WP) and slippery pulse(SP) were analyzed using one-way analysis of variance. The coefficients of variation(CV) were calculated for WP, SP and NP. Results: The APV difference between WP and NP in the 105 volunteers was statistically significant(6.26±0.28 vs. 6.04±0.36, P=0.048), as well as the difference between WP and SP(6.26±0.28 vs. 6.07±0.46, P=0.049). However, no statistically significant difference was found between NP and SP(P=0.75). WP showed a similar CV(4.47%) to those of NP(5.96%) and SP(7.58%). Conclusion: The new parameter APV could differentiate between NP or SP and WP. Accordingly, APV could be considered an useful parameter for the analysis of array pulse diagrams in Chinese medicine. 展开更多
关键词 PULSE SIGNAL ARRAY PULSE VOLUME PULSE SENSOR Chinese MEDICINE
A Gain-Switched Fe:ZnSe Laser Pumped by a Pulsed Ho,Pr:LLF Laser
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作者 李英一 鞠有伦 +3 位作者 戴通宇 段小明 郭春发 徐丽伟 《中国物理快报:英文版》 SCIE CAS CSCD 2019年第4期24-26,共3页
We demonstrate a gain-switched Fe:ZnSe laser pumped by a 2958 nm pulsed Ho,Pr:LLF laser. The maximum single pulse energy is 16.4uJ with a minimum pulse duration of 13.9 ns at the pulse repetition frequency of1 Hz when... We demonstrate a gain-switched Fe:ZnSe laser pumped by a 2958 nm pulsed Ho,Pr:LLF laser. The maximum single pulse energy is 16.4uJ with a minimum pulse duration of 13.9 ns at the pulse repetition frequency of1 Hz when the Fe:ZnSe crystal is cooled to 77 K by liquid nitrogen, corresponding to a slope efficiency of 22.9%.The central wavelength and FWHM linewidth are 3957.4 nm and 23.2 nm, respectively. The output energy monotonically decreases as the crystal temperature increases in the range 77–293 K. 展开更多
关键词 slope efficiency PULSE REPETITION frequency PULSE
Improving the data retention of phase change memory by using a doping element in selected Ge2Sb2Te5 预览
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作者 Yaoyao Lu Daolin Cai +5 位作者 Yifeng Chen Shuai Yan Lei Wu Yuanguang Liu Yang Li Zhitang Song 《半导体学报:英文版》 EI CAS CSCD 2019年第4期29-34,共6页
The crystallization characteristics of a ubiquitous T-shaped phase change memory (PCM) cell, under SET current pulse and very small disturb current pulse, have been investigated by finite element modelling. As analyze... The crystallization characteristics of a ubiquitous T-shaped phase change memory (PCM) cell, under SET current pulse and very small disturb current pulse, have been investigated by finite element modelling. As analyzed in this paper, the crystallization region under SET current pulse presents first on the corner of the bottom electron contact (BEC) and then promptly forms a filament shunting down the amorphous phase to achieve the low-resistance state, whereas the tiny disturb current pulse accelerates crystallization at the axis of symmetry in the phase change material. According to the different crystallization paths, a new structure of phase change material layer is proposed to improve the data retention for PCM without impeding SET operation. This structure only requires one or two additional process steps to dope nitrogen element in the center region of phase change material layer to increase the crystallization temperature in this confined region. The electrical-thermal characteristics of PCM cells with incremental doped radius have been analyzed and the best performance is presented when the doped radius is equal to the radius of the BEC. 展开更多
关键词 phase change memory CRYSTALLIZATION process SET CURRENT PULSE small disturb CURRENT PULSE finite ELEMENT simulation
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Analysis and optimization of high-power pulse transformer for SXFEL 预览
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作者 Yong-Fang Liu Hiroshi Matsumoto +3 位作者 Ming Gu Xiao-Xuan Zhou Yong-Hua Wu Zhi-Hao Chen 《核技术:英文版》 SCIE CAS CSCD 2019年第7期47-53,共7页
A C-band accelerator structure was used to accelerate electrons at the Shanghai soft X-ray free-electron laser test facility (SXFEL-TF) in Shanghai Institute of Applied Physics (SINAP). The microwave system of this ac... A C-band accelerator structure was used to accelerate electrons at the Shanghai soft X-ray free-electron laser test facility (SXFEL-TF) in Shanghai Institute of Applied Physics (SINAP). The microwave system of this accelerator structure used a 110 MW pulse modulator and a klystron (PV-5050) to provide the power supply. A pulse transformer is a crucial device in a modulator klystron system and plays significant roles in voltage level transformation, matching impedances, and polarity inversion. This study presents the optimization of a high-voltage pulse transformer. The design considerations of reducing flattop ringing and flattop droop, and shortening leading edge are provided. The model simulation, mechanical design, and the relevant experimental results are also presented. 展开更多
关键词 PULSE TRANSFORMER PULSE MODULATOR Flattop droop LEADING edge Flattop RINGING
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Femtosecond strong-field coherent control of nonresonant ionization with shaped pulses
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作者 佟秋男 廉振中 +3 位作者 赵亮 齐洪霞 陈洲 胡湛 《中国物理B:英文版》 SCIE EI CAS CSCD 2019年第3期153-160,共8页
The strong-field coherent control of the nonresonant ionization of nitrous oxide using shaped pulses is investigated.We study the dependence of periodic coherent oscillation of the total ionization yield on the variat... The strong-field coherent control of the nonresonant ionization of nitrous oxide using shaped pulses is investigated.We study the dependence of periodic coherent oscillation of the total ionization yield on the variation of laser phase parameters. The physical mechanism of the strong-field coherent control is investigated experimentally and theoretically by the nonresonant spectral phase interferences in the frequency domain. We show that the intense shaped pulses with broadband and off-resonance can be used as a robust strong-field coherent control method. 展开更多
关键词 COHERENT control nonresonant IONIZATION SHAPED PULSE
ReSe2 as a saturable absorber in a Tm-doped yttrium lithium fluoride(Tm:YLF) pulse laser
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作者 李春 冷雨欣 霍金金 《中国光学快报:英文版》 SCIE EI CAS CSCD 2019年第1期62-65,共4页
This study investigates the applicability of a few-layer structure ReSe2 as a saturable absorber(SA) for demonstrating a passively Q-switched pulse laser. The ReSe2 SA had a modulation depth of 6.86%. The Q-switched e... This study investigates the applicability of a few-layer structure ReSe2 as a saturable absorber(SA) for demonstrating a passively Q-switched pulse laser. The ReSe2 SA had a modulation depth of 6.86%. The Q-switched experiment was successful in delivering a maximum average output power of 180 mW at the wavelength of1906.5 nm. The optimal pulse train had a pulse width of 1.61 μs and a repetition rate of 28.78 kHz. The experiment results verify that the few-layer structure ReSe2 could behave as an excellent SA at all-solid-state lasers, increasing the selection of SAs at near 2 μm lasers. 展开更多
关键词 SA Tm:YLF PULSE LASER
Enhancement of optical emission generated from femtosecond double-pulse laser-induced glass plasma at different sample temperatures in air
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作者 王莹 陈安民 +5 位作者 王秋云 张丹 隋来志 李苏宇 姜远飞 金明星 《等离子体科学与技术:英文版》 SCIE EI CAS CSCD 2019年第3期98-107,共10页
In double-pulse laser-induced breakdown spectroscopy(DP-LIBS),the collinear femtosecond double-pulse laser configuration is experimentally investigated with different initial sample temperatures using a Ti:sapphire la... In double-pulse laser-induced breakdown spectroscopy(DP-LIBS),the collinear femtosecond double-pulse laser configuration is experimentally investigated with different initial sample temperatures using a Ti:sapphire laser.The glass sample is ablated to produce the plasma spectroscopy.During the experiment,the detected spectral lines include two Na(I)lines(589.0 nm and 589.6 nm)and one Ca(I)line at the wavelength of 585.7 nm.The emission lines are measured at room temperature(22°C)and three higher initial sample temperatures(Ts=100°C,200°C,and 250°C).The inter-pulse delay time ranges from-250 ps to 250 ps.The inter-pulse delay time and the sample temperature strongly influence the spectral intensity,and the spectral intensity can be significantly enhanced by increasing the sample temperature and selecting the optimized inter-pulse time.For the same inter-pulse time of 0ps(single-pulse LIBS),the enhancement ratio is approximately 2.5 at Ts=200°C compared with that obtained at Ts=22°C.For the same inter-pulse time of 150 ps,the enhancement ratio can be up to 4 at Ts=200°C compared with that obtained at Ts=22°C.The combined enhancement effects of the different initial sample temperatures and the double-pulse configuration in femtosecond LIBS are much stronger than that of the different initial sample temperatures or the double-pulse configuration only. 展开更多
关键词 LASER-INDUCED BREAKDOWN spectroscopy FEMTOSECOND laser double pulse emission ENHANCEMENT GLASS
雷达散射计低噪声脉冲行波管放大器电源研制 预览
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作者 张军 梁英 +3 位作者 路小月 王勇 樊经纬 范传强 《真空电子技术》 2019年第4期55-60,共6页
本文提出并实现了一种降低脉冲行波管放大器噪声的设计方案,解决了深空探测脉冲行波管放大器一直存在的阴极纹波噪声大、脉内及脉间噪声功率谱密度较差、低重频脉宽调制难以实现等技术难点。该方案首先利用脉宽调制(PWM)技术控制的有源... 本文提出并实现了一种降低脉冲行波管放大器噪声的设计方案,解决了深空探测脉冲行波管放大器一直存在的阴极纹波噪声大、脉内及脉间噪声功率谱密度较差、低重频脉宽调制难以实现等技术难点。该方案首先利用脉宽调制(PWM)技术控制的有源滤波器来降低卫星母线脉冲电流波动,进而减小电流对器件的冲击延长使用寿命;其次在升压电路后级使用基于比例积分微分(PID)调节的线性稳压器,来进一步地减小阴极纹波噪声;调制器电路使用多级悬浮调制器隔离技术及展频电路,实现降低纹波噪声和低重频脉宽调制的功能。基于以上设计,实现了脉冲行波管放大器噪声功率谱密度低于-90 dBm/Hz,产品杂波抑制度低于-75 dBc。将其用于相关型号散射计分系统的鉴定与验收试验,相关性能指标达到了国际水平,实现风速测量优于1.8 m/s的指标,成为国内首台空间应用的高可靠、长寿命脉冲行波管放大器。 展开更多
关键词 雷达 行波管 脉冲 高压 长寿命 可靠性
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A modified pulse charging method for lithium-ion batteries by considering stress evolution,charging time and capacity utilization
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作者 Yanfei ZHAO Bo LU +1 位作者 Yicheng SONG Junqian ZHANG 《结构与土木工程前沿:英文版》 EI CSCD 2019年第2期294-302,共9页
The stress evolution, total charging time and capacity utilization of pulse charging (PC) method are investigated in this pape匚 It is found that compared to the conventional constant current (CC) charging method, the... The stress evolution, total charging time and capacity utilization of pulse charging (PC) method are investigated in this pape匚 It is found that compared to the conventional constant current (CC) charging method, the PC method can accelerate the charging process but will inevitably cause an increase in stress and a decrease in capacity. The charging speed for PC method can be estimated by the mean current. By introducing stress control, a modified PC method called the PCCC method, which starts with a PC operation followed by a CC operation, is proposed. The PCCC method not only can accelerate charging process but also can avoid the stress raising and capacity loss occurring in the PC method. Furthermore, the optimal pulsed current density and switch time in the PCCC method is also discussed. 展开更多
关键词 fast CHARGING METHOD PULSE CHARGING stress evolution CHARGING time capacity UTILIZATION
高血压患者主动脉脉搏波传导速度影响因素探究 预览
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作者 田松枚 冯六六 +1 位作者 黄红漫 肖文颖 《心血管康复医学杂志》 CAS 2019年第3期315-317,共3页
目的:分析原发性高血压(EH)患者主动脉脉搏波传导速度(APWV)的影响因素。方法:我院336例EH患者被分为APWV升高组(281例)和APWV正常组(55例),对比两组临床资料,采用Logistic多元回归分析EH患者APWV的影响因素。结果:与APWV正常组比较,APW... 目的:分析原发性高血压(EH)患者主动脉脉搏波传导速度(APWV)的影响因素。方法:我院336例EH患者被分为APWV升高组(281例)和APWV正常组(55例),对比两组临床资料,采用Logistic多元回归分析EH患者APWV的影响因素。结果:与APWV正常组比较,APWV升高组年龄[(56.71±11.45)岁比(62.98±12.36)岁],糖尿病(5.45%比19.22%)、肥胖(18.18%比23.84%)、吸烟史(16.36%比30.60%)、高血压3级(12.73%比32.03%)比例,人体质量指数(BMI)[(22.53±2.07)kg/m2比(23.28±2.04)kg/m2],SBP[(139.64±12.85)mmHg比(147.39±13.30)mmHg]、DBP[(93.18±8.73)mmHg比(96.43±9.14)mmHg],TC[(5.18±0.91)mmol/L比(5.65±1.03)mmol/L]、LDL-C[(3.00±0.68)mmol/L比(3.24±0.72)mmol/L]、SCr[(110.71±52.39)μmol/L比(138.52±63.65)μmol/L]、SUA[(318.73±102.62)μmol/L比(354.28±108.35)μmol/L]水平显著升高,HDL-C(1.19±0.32)mmol/L比(1.09±0.30)mmol/L显著降低(P<0.05或<0.01)。多因素Logistic回归分析显示,年龄、糖尿病、SBP、TC、SCr、高血压等级是影响APWV的独立危险因素(OR=2.826~3.732,P均<0.05)。结论:年龄、糖尿病、SBP、TC、SCr、高血压等级是影响原发性高血压患者APWV的危险因素,因此,应采取相应的防治措施改善预后。 展开更多
关键词 高血压 脉搏 危险因素
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砂岩油藏注水井脉冲式在线注入酸化增注技术 预览
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作者 张彩虹 杨乾隆 +1 位作者 李发旺 贺耀 《钻井液与完井液》 CAS 北大核心 2019年第2期261-264,共4页
注水是实现油田长期稳产和高效开发的关键技术。受储层物性及注入水水质等因素的影响,华庆油田部分区块注水压力逐渐上升,高压欠注井越来越多,而目前现有的酸化增注技术暴露出有效期短、多次酸化增注低效、措施占井周期长、设备动迁困... 注水是实现油田长期稳产和高效开发的关键技术。受储层物性及注入水水质等因素的影响,华庆油田部分区块注水压力逐渐上升,高压欠注井越来越多,而目前现有的酸化增注技术暴露出有效期短、多次酸化增注低效、措施占井周期长、设备动迁困难、作业成本攀升等问题。针对以上问题,结合目标区块储层特征,通过大量室内实验调试对比,将常规六齿氨基羧酸螯合剂配位键升到八位,形成八齿螯合剂,增强了对金属离子的捕获、螯合、包裹作用,通过酸液复配,优选出一种适合目标储层的酸液体系;与此同时加强设备优化改进,添加远程操作系统,提高精准度;通过地面配套脉冲式柱塞泵注程序,形成了注水井脉冲式在线注入酸化增注技术。截至目前现场应用4井次,措施后平均单井注水压力下降9.0 MPa,单井日增注14.0 m3,平均有效期已达182 d,降压增注效果显著,有效期长;同时该技术解决了占井周期长、设备动迁困难等问题,现场操作简便,建议推广应用。 展开更多
关键词 注水井 高压欠注 降压增注 脉冲 在线酸化 COA-1S酸液体系
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Nanosecond Pulse Generation with Silver Nanoparticle Saturable Absorber
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作者 R.Z.R.R.Rosdin M.T.Ahmad +3 位作者 A.R.Muhammad Z.Jusoh H.Arof S.W.Harun 《中国物理快报:英文版》 SCIE CAS CSCD 2019年第5期31-34,共4页
Nanosecond pulse generation in an erbium-doped fiber laser (EDFL) passively mode-locked by a silver nanoparticle(SNP)-based saturable absorber(SA) is experimentally demonstrated. The SA is fabricated by depositing a n... Nanosecond pulse generation in an erbium-doped fiber laser (EDFL) passively mode-locked by a silver nanoparticle(SNP)-based saturable absorber(SA) is experimentally demonstrated. The SA is fabricated by depositing a nanosized SNP layer onto the surface of polyvinyl alcohol film through the thermal evaporation process. By inserting the SA into an EDFL cavity, stable mode-locked operation is achieved at 1561.5 nm with the maximum pulse energy up to 52.3 nJ. The laser operates at a pulse repetition frequency of 1.0 MHz with a pulse width of 202 ns. These results suggest that SNPs could be developed as an effective SA for mode-locking pulse generation. 展开更多
关键词 SA Nanosecond PULSE Generation with SILVER NANOPARTICLE Saturable ABSORBER
A novel α-fetoprotein-MIP immunosensor based on AuNPs/PTh modified glass carbon electrode
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作者 Yuxuan Lai Chuanxiang Zhang +4 位作者 Yan Deng Gaojian Yang Song Li Congli Tang Nongyue He 《中国化学快报:英文版》 SCIE CAS CSCD 2019年第1期160-162,共3页
A new α-fetoprotein-MIP(AFP-MIP) immunosensor based on glass carbon electrode(GCE) modified with polythionine(PTh) and gold nanoparticles(AuNPs) was successfully fabricated for sensitive detection ofα-fetoprotein(AF... A new α-fetoprotein-MIP(AFP-MIP) immunosensor based on glass carbon electrode(GCE) modified with polythionine(PTh) and gold nanoparticles(AuNPs) was successfully fabricated for sensitive detection ofα-fetoprotein(AFP). Through controlling electropolymerization, A “polydopamine(PDA)-AFP” complex was achieved applying AFP as template and dopamine(DA) as imprinted monomers. After elution, the specific cavities can adsorb the target molecules. Using differential pulse voltammetry(DPV) detection,the peak current decreased with the increase in concentration of AFP, and the linear response range of the AFP-MIP immunosensor was from 0.001 ng/mL to 800 ng/mL with the detection limit as low as0.8138 pg/mL. The MIP immunosensor could become a new promising method for the detection of AFP.Furthermore, this MIP sensor was demonstrated in testing AFP in human serum samples with satisfactory results. 展开更多
关键词 Molecular IMPRINTING polymer α-Fetoprotein ELECTROPOLYMERIZATION Differential pulse VOLTAMMETRY IMMUNOSENSOR
Development of gas tungsten arc welding using current pulsing technique to preclude chromium carbide precipitation in aerospace-grade alloy 80A 预览
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作者 P.Subramani M.Manikandan 《矿物冶金与材料学报:英文版》 SCIE EI CAS CSCD 2019年第2期210-221,共12页
Weldments were produced using gas tungsten arc welding(GTAW)and pulsed current gas tungsten arc welding(PCGTAW)techniques with ERNiCr-3 filler wire.Macro examination revealed that the resultant weldments were free fro... Weldments were produced using gas tungsten arc welding(GTAW)and pulsed current gas tungsten arc welding(PCGTAW)techniques with ERNiCr-3 filler wire.Macro examination revealed that the resultant weldments were free from defects.A refined microstructure was observed in the weldment fabricated through PCGTAW.Scanning electron microscopy(SEM)analysis revealed secondary phases in the grain boundaries.Energy-dispersive X-ray spectroscopy(EDS)analysis revealed that microsegregation of Cr carbide precipitates was completely eradicated through PCGTAW.The microsegregation of Nb precipitates was observed in the GTA and PCGTA weldments.X-ray diffraction(XRD)analysis revealed the existence of M23C6 Cr-rich carbide and Ni8Nb phases in the GTA weldments.By contrast,in the PCGTA weldments,the Ni8Nb phase was observed.The Cr2Ti phase was observed in both the GTA and the PCGTA weldments.Tensile tests showed that the strength and ductility of the PCGTA weldments were slightly higher than those of the GTA weldments. 展开更多
关键词 NI-BASED SUPERALLOY welding pulse CURRENT MICROSEGREGATION CHROMIUM CARBIDE
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微加热器上不同工质的气泡动力学实验 预览
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作者 张旭浩 范聪 +2 位作者 余海洋 黄雪琴 邓佩刚 《武汉工程大学学报》 CAS 2019年第2期173-178,共6页
设计并采用MEMS工艺制造了一种特征尺寸10μm并能产生单一稳定微米气泡的Pt薄膜加热摄像头和MATLAB程序定量研究了在乙醇、除气水和纳米流体中微气泡的动力学过程。研究发现:不同流体中,随着脉冲宽度的增加气泡直径增大,所需的起始功率... 设计并采用MEMS工艺制造了一种特征尺寸10μm并能产生单一稳定微米气泡的Pt薄膜加热摄像头和MATLAB程序定量研究了在乙醇、除气水和纳米流体中微气泡的动力学过程。研究发现:不同流体中,随着脉冲宽度的增加气泡直径增大,所需的起始功率减小。乙醇中气泡成核所需的功率最小,气泡直径最小;而纳米流体中所需功率最大,气泡直径也最大。通过表面张力与成核的理论模型对此进行了初步的理论分析。 展开更多
关键词 微加热器 气泡动力学 脉冲 纳米流体
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Multi-stage Electrostatic Separation for Recovering of Aluminum from Fine Granules of Black Dross
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作者 曹云霄 WANG Zhiqiang +1 位作者 WANG Jinjun 李国锋 《武汉理工大学学报:材料科学英文版》 SCIE EI CAS 2019年第4期925-931,共7页
Separation of aluminum from fine granules of black dross, which is a waste by-product in secondary aluminum production, was investigated. The separation was performed by a multi-stage electrostatic separation method. ... Separation of aluminum from fine granules of black dross, which is a waste by-product in secondary aluminum production, was investigated. The separation was performed by a multi-stage electrostatic separation method. There are three stages to complete the separation, including preliminary separation, pulse charging enhancement and secondary concentration. Chemical and mineralogical compositions of collection products were analyzed and determined by X-ray diffraction(XRD) and X-ray Fluorescence(XRF). After multistage electrostatic separation, the Al2O3 content of the collection products increases from 50.74% to 69.77%.The mineralogical phase analysis indicates that the final recovery of metallic aluminum phase increases from 8%to 37%, and the aluminum oxide phase increases from 20% to 26%. The research results show the multi-stage electrostatic separation method is effective for recovering of aluminum from fine granules of black dross, and upgrades the black dross to a recoverable material. 展开更多
关键词 electrostatic separation pulse charging ALUMINUM recovery FINE GRANULES BLACK DROSS
Passively Q-switched diode-pumped Tm,Ho:LuVO4 laser with a black phosphorus saturable absorber
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作者 李林军 李天鑫 +4 位作者 周龙 范剑英 杨玉强 谢文强 李莎莎 《中国物理B:英文版》 SCIE EI CAS CSCD 2019年第9期203-205,共3页
We presented a passively Q-switched(PQS) diode-pumped c-cut Tm, Ho:LuVO_4 laser with a black phosphorus saturable absorber for the first time.Under PQS mode, an average output power of 0.86 W and a peak power of 2.32 ... We presented a passively Q-switched(PQS) diode-pumped c-cut Tm, Ho:LuVO_4 laser with a black phosphorus saturable absorber for the first time.Under PQS mode, an average output power of 0.86 W and a peak power of 2.32 W were acquired from the Tm, Ho:LuVO4 laser with the pump power of 14.55 W, corresponding to a pulse width of 2.89 μs,a pulse repetition rate of 71.84 kHz, and a pulse energy of about 6.70 μJ. 展开更多
关键词 passively Q-switched(PQS) technology Tm Ho:LuVO4 crystal pulse WIDTH
低频脉冲磁场作用下计算机效应的试验研究 预览
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作者 潘征 石立华 +3 位作者 李跃波 郑颖 熊久良 黄刘宏 《电波科学学报》 EI CSCD 北大核心 2019年第3期355-362,共8页
低频脉冲磁场是一种常见电磁干扰源,可以在雷电放电、地面核爆炸及生产生活等多种活动中产生,具有低频、低阻和时变等多重特性,可通过直接穿透和磁电感应作用于计算机系统上,对其产生干扰或毁伤.为确定低频脉冲磁场对计算机系统的效应规... 低频脉冲磁场是一种常见电磁干扰源,可以在雷电放电、地面核爆炸及生产生活等多种活动中产生,具有低频、低阻和时变等多重特性,可通过直接穿透和磁电感应作用于计算机系统上,对其产生干扰或毁伤.为确定低频脉冲磁场对计算机系统的效应规律,文章利用螺线管脉冲磁场模拟装置,开展了低频脉冲磁场作用下联想品牌计算机(包括2款台式机和一款笔记本)效应的试验研究,得到了扰乱阈值和效应规律,分析了磁场特征参数与效应现象的关系,并与相关研究成果进行了对比.其中脉冲磁场上升时间在数μs至数百μs之间,磁感应强度最大约70mT.研究结果符合理论预期,并与现有成果逻辑关系一致,可为计算机系统及相近设备的低频脉冲磁场防护提供参考和依据. 展开更多
关键词 低频 脉冲 磁场 计算机效应 试验研究
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Improvement of machining consistency during through-mask electrochemical large-area machining
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作者 Guoqian WANG Hansong LI +1 位作者 Chao ZHANG Di ZHU 《中国航空学报:英文版》 SCIE EI CAS CSCD 2019年第4期1051-1058,共8页
Electrochemical machining(ECM) is an important machining technique for the aeronautical manufacturing industry. Through-mask ECM is a form of ECM for machining metal parts with a hole array. In order to extend the mac... Electrochemical machining(ECM) is an important machining technique for the aeronautical manufacturing industry. Through-mask ECM is a form of ECM for machining metal parts with a hole array. In order to extend the machining area, a serpentine flow channel with multiple curves was used for through-mask ECM. With the extension of the flow channel, ensuring a machining consistency along the flow channel has been a challenge. The electrolyte conductivity is the main factor affecting the machining consistency. To analyze the change rules of the electrolyte conductivity, variations in the bubble rate and the temperature of the electrolyte in the electrolyte flow were explored under different power sources. Results indicate that pulse-power machining can reduce variations in the bubble rate and the temperature in the serpentine flow channel, and then the electrolyte conductivity can be stabilized within a very small range. Experiments using through-mask ECM were conducted in two types of power sources. Experimental results support the importance of pulse-power machining. A 14×28 hole array with a 2.5 mm diameter was fabricated by a pulsed power source. The aperture deviation of the hole array is less than 0.05 mm, and the roundness deviation is less than 15 lm when fabricated with pulse machining. 展开更多
关键词 Hole array Numerical simulation Pulse MACHINING SERPENTINE flow channel Through-mask ELECTROCHEMICAL MACHINING
A new solution to enhance cuttings transport in mining drilling by using pulse jet mill technique
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作者 LIU YongSheng GAO DeLi +3 位作者 WEI Zheng BALACHANDRAN Balakumar WANG ZhenQuan TAN LeiChuan 《中国科学:技术科学英文版》 SCIE EI CAS CSCD 2019年第5期875-884,共10页
In horizontal drilling, the cuttings bed is frequently formed to result in severe problems such as backing pressure, binding of bottom hole assembly(BHA) and even sticking of tool. Practice and research show that the ... In horizontal drilling, the cuttings bed is frequently formed to result in severe problems such as backing pressure, binding of bottom hole assembly(BHA) and even sticking of tool. Practice and research show that the smaller particle size is, the more favorable to carry out from bottom of hole in extended reach well or horizontal well. This paper presented a new solution to enhance cuttings transport in mining drilling through a new type of bit called pulsed mill bit(PMB) by using pulse jet mill technique. It provides a promising solution to enhance the efficiencies of rock breaking and cuttings carrying for pulsed jet,sucking cuttings to decrease the chip hold down effect, and reducing cuttings’ diameter to eliminate cuttings bed. The design was supported by the calculation models of Helmholtz resonator natural frequency, optimal drilling fluid flow rate of resonator,drilling fluid flow velocity in forward jet channel, critical impact velocity of cuttings and minimum length of the accelerating cavity. Meanwhile, factors affecting optimal drilling fluid flow rate, critical impact velocity of cuttings and minimum length of accelerating cavity were investigated. Case study showed a good consistency between the calculation results and the related theories. It is concluded that optimal drilling fluid flow rate increases with the increase of inlet and outlet cavity’s diameter, and decreases with the increase of the diameter of the resonant cavity. Critical impact velocity of cuttings increases with the energy conversion factor(β) and ROP, while decreasing with the final size of the cuttings(dt). This effect is obvious when β<0.2, ROP<3.048 mh-1 and dt<0.3 mm. Minimum length of the accelerating cavity decreases with the increase of the resonator’s natural frequency and separation coefficient(α) of drilling fluid flow rate. This study provides a promising solution to remove cuttings bed in horizontal well. 展开更多
关键词 PULSE jet MILL TECHNIQUE CUTTINGS bed HELMHOLTZ RESONATOR optimal flow rate critical impact velocity
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