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1. chinaXiv:201711.02787 [pdf]

光源混合频率调制的光热干涉工作点无源控制方法研究

李树旺
Subjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.

相位漂移现象是干涉测量中普遍存在的问题,对解调结果的准确度带来巨大影响。提出了一种光源混合频率调制的闭环工作点无源控制方法,通过直接高频调制光源的方式从单路干涉信号中提取出相位漂移信号,并利用低频控制信号对光源直接调制的方式予以补偿;通过高频、低频调制信号的配合,解决了单路干涉信号的工作点跟踪问题,以无源控制的方式保证干涉测量系统始终工作在最灵敏的线性区域。测试了光源在不同调制频率下的调制特性,比较了系统开、闭环状态下工作点的变化趋势,无源闭环工作点控制法与相位载波解调算法的对比解调结果表明两种方法解调结果相关度超过 ,证明该方法可行。

submitted time 2017-11-29 Hits1045Downloads621 Comment 0

2. chinaXiv:201711.02788 [pdf]

Analysis and mitigation of the carrier phase delay effect of the digital phase generated carrier algorithm

邵士勇
Subjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.

We present an improved digital phase generated carrier (PGC)algorithm based on the synchronous carrier restoration(SCR) method to mitigate the carrier phase delay effects. The most distinguishing feature of this method is that it picks up the carrier signal information (frequency and phase) from the interference signal directly and accomplishes the processing of carrier signal restoration synchronically. In comparison with the traditional one which adopts the initial carrier signal, the total-harmonic-distortions of the SCR method is only 0.091%, lower than the traditional one's 18.38%, and the signal-to-noise-ratio increases 29 dB. Further, we derive the analytic expression of distortion component and verify it by experiments. Thistechnique may be potentially applied in a long distance large-scale distributed fiber-optic interferometer sensors array.

submitted time 2017-11-29 Hits974Downloads568 Comment 0

3. chinaXiv:201711.02561 [pdf]

Analysis of beam optics for a high power ion source

谢亚红
Subjects: Physics >> Nuclear Physics

The high power ion source is the key parts of neutral beam injector. Generally speaking, the beam power should matching the extraction voltage for a given accelerator. In order to get higher beam power with lower beam extraction voltage, the beam optics of accelerator was analyzed based on the structure of EAST-NBI tetrode accelerator. The beam optics of a tetrode accelerator and a new designed three-electrode accelerator was analyzed with beam energy of 50 keV. The results shown that, the two types of accelerator can get high beam perveance (4.6μp) with lower beam divergence angle compare to the EAST-NBI accelerator (2.8μp). And the tetrode accelerator can gets lower beam divergence angle compare to the three-electrode accelerator, but the electric field between two electrode is much higher than three-electrode accelerator. The results can help for the ion source design of high power ion source.

submitted time 2017-11-24 Hits1495Downloads732 Comment 0

4. chinaXiv:201711.00012 [pdf]

Analysis of algebraic reconstruction technique for accurate imaging of gas temperature and concentration based on tunable diode laser absorption spectroscopy.pdf

夏晖晖
Subjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.

An improved algebraic reconstruction technique(ART) with tunable diode laser absorption spectroscopy(TDLAS) is presented in this paper for determining two-dimensional distribution of H2O concentration and temperature in a simulated combustion flame. This work aims to simulate the reconstruction of spectroscopic measurements by a multi-view parallel-beam scanning geometry and analyze the effects of projection rays on reconstruction accuracy. It finally proved that reconstruction quality dramatically increases with increasing number of projection rays until they are more than 180 for 20×20 grid, and after that point, the number of projection rays has little impact on reconstruction accuracy. It is clear that the temperature reconstruction results are more accurate than the water vapor concentration by traditional concentration calculation method, the study in this article also proposed an innovative way to reduce the error of concentration reconstruction and improve the reconstruction quality greatly, the capability of this new method is evaluated by appropriate assessment parameters. By using this new approach, the concentration reconstruction accuracy is not only badly improved, but also a suitable parallel-beam arrangement is put forward for sake of high reconstruction accuracy and simplicity of experimental validation. At last, a bimodal structure of combustion region is assumed to demonstrate the robustness and universality of the proposed method. Numerical investigation indicates that the proposed TDLAS tomographic algorithm is capable for accurate temperature and concentration profiles detection, this feasible formula for reconstruction research is expected to resolve several key issues in practical combustion devices.

submitted time 2017-11-02 Hits857Downloads528 Comment 0

5. chinaXiv:201709.00102 [pdf]

超声与表面活性剂对维生素K2渗漏发酵的协同作用研究

赵根海; 杨强; 方雪; 刘会; 孙小雯; 倪文枫; 郑之明
Subjects: Biology >> Bioengineering

维生素K2是一种人体必需维生素,具有促进凝血酶原产生和骨钙素合成等作用,在损伤细胞修复方面也有明显效果。微生物发酵法制备维生素K2具有环境影响小、生物活性高、生产成本低等优点,是维生素K2规模化制备的发展趋势。利用超声波和表面活性剂提高微生物发酵过程中菌体细胞通透性是一种常见的细胞代谢人工调控方法。低功率超声波的空化作用可以在细胞表面瞬间造成微伤,使细胞膜局部破裂从而改变细胞膜的通透性,有利于胞内物质释放或胞外物质进入细胞内。表面活性剂有助于提高营养物质溶解性,降低培养基表面张力,减小菌体表面和培养基的界面阻力,从而促进营养物质和菌体代谢产物的跨膜传输。 本文对实验室保藏的一株产维生素K2黄杆菌(Flavobacterium.sp)Fla-M进行低功率超声波辐照和表面活性剂处理,考察二者在提高细胞渗漏发酵方面的协同作用。首先在500 mL摇瓶中对Fla-M进行表面活性剂(聚氧乙烯油醚POE)添加时间和添加浓度优化,发现在发酵起始阶段添加1%POE效果最佳,发酵结束时生物量为13.4 g/L,胞外维生素K2产量为36.3 mg/L,相比于未添加POE的对照组(生物量7.32 g/L,胞外维生素K2 0.85 mg/L)分别提高了83.5%和41倍,扫描电镜观察发现在添加POE发酵的菌体表面聚集了大量表面活性剂胶团,由于POE与细胞膜磷脂分子结构相似,二者可能相溶形成混合胶束改变了细胞膜结构,进而改善细胞膜的通透性。其次在500 mL摇瓶中对Fla-M进行了超声方式、超声时机、超声功率以及作用时间研究,发现在菌体生长稳定期(发酵第5 d)、120 W 20 KHz条件下,插入式超声98 S(每次3 S,间隔4 S)效果最佳,发酵结束时生物量为11.1 g/L,胞外维生素K2达到50.1 mg/L, 相比于未超声对照组(生物量7.32 g/L,胞外维生素K2 0.85 mg/L),分别提高了51.6%和58倍。透射电镜观察发现超声波处理后尽管细胞膜完整但磷脂双分子层界限模糊,且细胞膜表面有孔状破损结构,可见疑似内容物外渗现象。在上述最优条件下,在500 mL摇瓶中综合运用POE和超声的处理方法,生物量和胞外维生素K2产量在发酵6 d后达到最大值,分别为生物量11.5 g/L,胞外维生素K2 59.7 mg/L,较单独运用POE或超声的方法发酵周期缩短3 d、胞外维生素K2产量分别提高64.4%和19.1%。运用排斥性染料碘化丙啶(PI)对发酵后细胞进行流式细胞仪检测,设001号为阴性对照,即未加荧光载体的未处理菌体的荧光信号;002号为处理的菌体加荧光载体的荧光信号;003号为未处理菌体加荧光载体的荧光信号;004号为阳性对照,即死细胞加荧光载体的荧光信号,阴性对照的001号菌体自发荧光区域以外的面积M1占总面积的比例预设为0,结果显示004号的M1占总面积的比例17.21%>002号M1占总面积的比例8.89%>003号M1占总面积的比例1.21%,说明死菌体的细胞膜通透性>渗漏培养菌体的细胞膜通透性>无渗漏培养菌体的细胞膜通透性,验证了经超声和表面活性剂处理后,菌体细胞膜通透性大幅提高。本研究对发酵法制备维生素K2的产业化开发具有一定的借鉴意义。

submitted time 2017-09-20 Hits22123Downloads1057 Comment 0

6. chinaXiv:201708.00285 [pdf]

The behaviors of helium atoms in tantalum, rhenium and osmium

尤玉伟
Subjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.

We present systematic first-principles studies of occupancy, diffusion, and segregation of He atoms, as well as underlying evolution mechanism of He clusters in Ta, Re and Os precipitates to help to understand the effect of alloying solutes on He retention and bubble formation. It is found that single He atom prefers tetrahedral (T) site in Ta and basal octahedral (BO) site in Re and Os. Single He atom prefers the diffusion path from one T site to the closest T site in Ta, and the diffusion path from one BO site to the next BO site passing an octahedral site along $\langle$0001$\rangle$ direction in Re and Os. The diffusion of single He atom in Ta, Re and Os is relatively difficult than that in W. He atoms are energetically favorable to segregate at interstitial sites forming He$_{n}$ clusters in Ta, Re and Os, and form close-packed He monolayer structure between (110) planes in Ta. The binding strength of He$_{n}$ cluster in Ta, Re and Os is relatively small than that in W (W>Os>Re>Ta). Compared with interstitial sites, He atoms are more energetically favorable to aggregate in vacancy cluster forming VacmHen. The binding strength order of VacmHen cluster in the systems obeys W>Os>Re>Ta. We thus expect that the presence of Ta and Re may contribute to reduce He retention and bubble formation in W.

submitted time 2017-08-23 Hits634Downloads422 Comment 0

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