Modal correction for fiber-coupling efficiency in free-space optical communication systems through atmospheric turbulence

High-speed free-space optical communication systems have recently used fiber-optical components. The coupling efficiency with which the received laser beam can be coupled into a single-mode fiber is noticeably limited by atmospheric turbulence due to the degradation of its spatial coherence. Fortunately, adaptive optics (AO) can alleviate this limitation by partially correcting the turbulence-distorted wavefront. The coupling efficiency improvement provided by Zernike modal AO correction is numerically evaluated. It is found that the first 3-20 corrected polynomials can considerably improve the fiber-coupling efficiency. The improvement brought by AO is compared with that brought by a coherent fiber array. Finally, a hybrid technique that integrates AO and a coherent fiber array is proposed. Results show that the hybrid technique outperforms each of the two above-mentioned techniques. (C) 2009 Elsevier GmbH. All rights reserved.

厌氧好氧一体化生物反应器处理发酵废水的中试研究

一体化反应器由于投资少、占地小、管理运行方便等优点而备受青睐。但现有的一体化反应器大都适用于处理中低浓度废水，耐受负荷普遍偏低。本课题研制出新型高效的厌氧好氧一体化生物反应器，旨在通过反应器结构优化、高效微生物载体研制、配合高效微生物菌剂技术处理中高浓度有机废水，实现高效和低耗，降低设备造价，提高反应器运行稳定性。 首先开展了菌剂对废水的适配试验。采用15种不同的微生物菌剂，以葡萄糖配水、中药提取废水、啤酒废水、氨氮配水为基质，分别测定了微生物菌剂的耗氧速率和厌氧比产甲烷速率，以其为指标比较了各菌剂对废水的适配性。根据结果选择活性高的14＃、8＃、10＃菌剂，在试验室进行了菌剂对废水的连续处理试验，取得良好的处理效果，为菌剂在厌氧好氧一体化生物反应器的小试、中试中的应用奠定了基础。 经小试研究后，又对厌氧好氧一体化生物反应器进行了处理发酵废水的中试研究。试验结果表明，反应器启动快，系统有机负荷2.72 kgCODm-3d-1时整个反应器去除率保持在84.5％～93.19％，在30多天内一次启动成功。冲击负荷试验中，系统总有机负荷最高可达到8.88 kgCODm-3d-1，系统去除率稳定在88.10％～96.88%，说明反应器处理效率高，抗冲击能力强。稳定运行期间，COD去除率可达90％以上，各项指标都能达到国家排放标准。 此外，对反应器配套系统高效菌剂、高分子复合颗粒载体进行了研究。结果显示，菌剂与反应器适配良好，各功能区形成了丰富、高活性的微生物，厌氧区颗粒污泥TS高达83.9 gL-1，VS/TS为56.9％～57.4％，比产甲烷活性为280～350 mLCH4 gvss-1d-1；好氧区固定化微生物TS高达1.921 gL-1，VS/TS为94.02～94.30％。对载体性能的研究表明，此高分子复合颗粒载体密度适中，易于流化，不易流失；粗糙多空，易于挂膜；且无生物毒害作用，稳定安全，是一种优良的生物载体。反应器各功能区对废水的降解过程分析，说明了反应器、菌剂、载体适配良好，在其协同作用下，实现了污染物的高效降解。 The integrated reactors were popular because of their characteristics such as little investment, small occupation of land, convenient of manage and running etc. But the present integrated reactors were mostly applied for treating wastewater of low concentration, the load tolerance was generally on the low side. A new type integrated anaerobic-aerobic bio-reactor was developed, which was conducted to treating organic wastewater of middle or high concentration by optimization of reactor structure, development of efficient microbe carrier and adaptation of high active microbial blends, to achieve high efficiency and low consume, reduce equipment cost, enhance running stabilization of reactor. The adaptability test of microbial blends on different wastewater was carried on firstly. Oxygen consumption rate and anaerobic specific activity of methane producing of 15 different microbial blends were measured separately taking glucose artificial wastewater, Chinese herb extracting wastewater, brewery wastewater and ammonia nitrogen artificial wastewater as substrate, by which the adaptabilities of different microbial blends to wastewater were compared. According to the results high active microbial blends 14#, 8# and 10# were selected and used in the continuous treatment of wastewater in the laboratory and had obtained good effect, which had laid a foundation for application microbial blends to small scale test and pilot test of integrated anaerobic-aerobic bio-reactor. After the small scale test, the pilot test of the integrated anaerobic-aerobic bio-reactor treating fermentation wastewater was carried on. The test results showed fast initiation of the reactor. When system organic load reached 2.72 kgCODm-3d-1the COD removal rate of the reactor was stable between 84.5%～93.19% and it initiated successfully in more than 30 days at a time. In the load shock test the maximum organic load of system could reach to 8.88 kgCODm-3d-1 and the COD removal rate could be stable between 88.10%~96.88% which indicated that the reactor was efficient for treating wastewater and had strong resistance to shock load. At stable running period the COD removal rate of the reactor was over 90% and each index of wastewater could reach to the national discharge standards. In addition, the high active microbial blends and the macromolecule compound granule carrier, the matching system of the reactor was studied. It showed that the microbial blends adapted well to the reactor and abundant and high active microbes were formed in each functional field. The TS of granule sludge in anaerobic field was as high as 83.9 gL-1, the VS/TS was 56.9%~57.4%, the specific activity of methane producing was 280~350 mLCH4 gvss-1d-1. And the TS of immobilized biological granule was as high as 1.921 gL-1, the VS/TS was 94.02%~94.30%. Study on the carrier showed that the self-made macromolecular compound granule carrier was moderate of density, easy of fluidization, unease of running off, rough and porous, easy of films fixation, no bio-toxic, stable and safe, was a kind of superior carrier. Analysis of degradation process in each functional field confirmed the reactor, microbial blends and carriers were in good adaptation and wastewater was decontaminated by their cooperation.

High-efficiency transfer and expression of AdCMV-p53 in human cervix adenocarcinoma cells induced by subclinical-dose carbon beam radiation

Purpose The aim of this study is to evaluate the eVect of carbon-beam irradiation on adenovirus-mediated p53 transfer in human cervix adenocarcinoma.Materials and methods The HeLa cells pre-exposed to carbon-beam or -ray, were infected with replication-deficient adenovirus recombinant vectors, containing human wild-type p53 (AdCMV-p53) and green Xuorescent protein (GFP) (AdCMV–GFP), respectively. The GFP transfer and p53 expression were detected by Xow cytometric analysis.Results The GFP transfer frequency in C-beam with AdCMV-GFP groups was 38–50% more than that inγ-ray with AdCMV–GFP groups. The percentage of p53 positive cells in the C-beam with AdCMV–p53 groups was 34–55.6% more than that in γ-ray with AdCMV-p53 groups (p < 0.05), suggesting that subclinical-dose C-beam irradiation could signiWcantly promote exogenous p53 transfer and p53 expression, and extend the duration of p53 expression in the HeLa cells. The expression of p21 increased with p53 expression in HeLa cells. The survival fractions for the 0.5–1.0 Gy C-beam with AdCMV-p53 groups were 38–43% less than those for the isodose γ-ray with AdCMV-p53 groups, and 31–40% less than those for the C-beam only groups (p <0.05).Conclusions The subclinical-dose C-beam irradiation could signiWcantly promote the transfer and expression of exogenous p53, extend the duration of p53 expression, and enhance the suppression of p53 on cervix adenocarcinoma cells.

Efficiency calibration of neutron detector array for beta decay of exotic nuclei

The research of the in-beam efficiency calibration of Neutron Detector Array of Peking University using N-17 and C-16 beams was introduced in this paper. The efficiency of neutron wall and ball are comparable to the foreign similar devices and neutrons can be detected from low to high energies in high efficiency.

Study of buncher efficiency in axial injection system of SFC

In order to reduce the influence of the stray electric field of the buncher in the axial injection system of SFC and to improve the injection efficiency of SFC, the existing buncher electrode is investigated and a new electrode is designed. The influences of the electric field to the beams for the both cases are simulated. The simulation results show that the bunching efficiency is improved from 55% to 74% with the new electrode. At the same time, the influence of the space charge is computed and according to the results, the location of the buncher is readjusted too.