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移动前传网络是C-RAN（集中式/云无线接入网）技术中的重要部分。随着现代无线接入网络的发展演进,用户带宽需求的快速增长对网络的传输速率提出了更高的要求。文章回顾了移动前传网络的基本内容,分析了前传网络需要满足的各项需求,并对当前提出的各种前传网络的解决方案进行了详细的介绍。

基于FTN（超Nyquist）方案是一种高频谱效率传输方案。文章总结了目前国际上最新的基于FTN传输方案:级联多模盲均衡FTN、数字FTN和SOFTN（软输出FTN）。其中,级联多模盲均衡FTN方案能有效地抑制噪声和信道间串扰,数字FTN方案能有效地简化系统结构,而SOFTN方案的频谱效率最高。对这三种方案的性能和原理进行了详细分析和比较,以期作为未来长距离、大容量光纤通信系统设计的依据。

提出并证明了一种基于副载波单边带分插复用的正交频分复用无源光网络（OFDM-PON）系统的新型结构。该结构的下行传输是基于单边带的OFDM-4-正交幅度调制（QAM）,传输速率为10 Gbit/s;而上行传输则是利用下行信号中保留的另一条边带进行2.5 Gbit/s速率的幅移键控（ASK）调制,采用时分多路接入方式。该方案可以较好地避免双向传输中的后向瑞利散射,考虑后向散射情况下,下行信号功率代价

提出一种新的具有较大带宽延时积（BDP）的光缓存结构。该结构基于一个单独的微环谐振腔和一个OFDM（正交频分复用）技术的发射机。较大的带宽延时积是通过将数据分布在OFDM的子载波上然后由谐振腔来获得的。建立了一个包括整个系统的数值模型,并且在仅考虑5条子载波的仿真中实现了较大的带宽延时积。

随着接入网带宽需求和业务支持需求的快速发展,环形结构的无源光网络（PON）的应用越来越重要,更长距离、支持更多光网络单元、与环形网络无缝融合已经成为PON在城域网中继续发展的3大要求。文章详细论述了新型环树融合拓扑结构的PON的原理及关键技术,讨论了这种新型结构的典型应用,总结了不同方案的优缺点,为未来接入网与城域网更深层次的融合发展的研究提供参考。

文章介绍了两种补偿相位噪声的新技术,分别是补偿激光器相位噪声的数字前馈载波恢复算法和补偿非线性相位噪声的数字反向传播算法。其中数字前馈载波恢复算法能有效地提高能够容忍的激光器线宽;数字反向传播算法减少了非线性噪声,并能够大幅提高发射功率,以提高信噪比。

Copyright of Coal Science & Technology (0253-2336) is the property of Coal Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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Copyright of Journal of South China Agricultural University is the property of Gai Kan Bian Wei Hui and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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Copyright of Chinese Journal of Cancer Biotherapy is the property of Editorial Office of Chinese Journal of Cancer Biotherapy and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Coal Science & Technology (0253-2336) is the property of Coal Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

内镜下经十二指肠主乳头插管已成为治疗胰腺疾病的重要手段，但在某些病例，经主乳头插管无法获得 成功，此时经十二指肠副乳头插管也可作为胰腺疾病的治疗手段。通过向副乳头喷洒亚甲蓝和靛胭脂，静脉注射促 胰液素使副乳头开口明显。副乳头插管方式主要为传统的导丝引导技术、针刀预切开技术、会合技术、双导丝技术 等。内镜干预措施包括副乳头括约肌切开术、副乳头扩张术、副胰管支架置入术、结石处理和狭窄处球囊扩张等，对 胰腺分裂、慢性胰腺炎、胰腺假性囊肿及沟槽状胰腺炎等疾病的治疗有较好的疗效。经副乳头插管行内镜治疗也可 出现术后胰腺炎、出血、穿孔等并发症。 [ABSTRACT FROM AUTHOR]

Copyright of CT Theory & Applications is the property of Editorial Department of CT Theory & Applications and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The problem of roadway support in deep coal mining or hard roof can be solved by special surrounding rock pressure release of stagger layout roadway. In this paper, the surrounding rock characteristic of gob-side roadways with or without coal pillar were analysed. Then the movement of main roof which has large impact on the stability of surrounding rock of gob-side roadway was discussed. The mechanical mechanism of pressure releasing and deformation yielding of surrounding rock structure system was studied by mechanical analysis and laboratory experiment. Results shows that the stagger layout enables roadway to be away from the stress concentration zone which transfers the pressure and avoids the problem of high ground stress. The gangue pillar structure cushions the dynamic load of falling roof and undertakes the weight of key block. The roof made up by gangue gives enough space for hard roof’ s movement which in another way protects the roadway. [ABSTRACT FROM AUTHOR]

In order to study the bearing deformation characteristics of large-size broken rock, a testing system used for bearing deformation test of large-size broken rock was developed. The typical sandstone from the roof was chosen as sample. In view ol the particle size distribution characteristics and stress state of broken rock in caving zone, the size distribution of broken rock obeyed the law of normal distribution and the loading pattern was designed to step loading. The test results indicated that along with the increase of axial load, the axial deformation of broken rock increases gradually, the residual bulking coefficient and porosity decrease gradually, which are more obvious in loading stage than that in constant load stage. In the early constant load stage, the axial deformation of broken rock grows rapidly, then tends to be slow and steady gradually, the relationship between strain and time meets the logarithmic relationship. In loading stage,the D-value of axial strain decreases first and then increases,in constant load stage,which is opposite. The bearing deformation of large-size broken rock is consisted of two parts, instantaneous compression deformation and long-term deformation, which reflects in the position adjustment of rock particles, smaller original and newborn rock particles slide and fill the gap between larger rock particles. The 15-20 mm particle size of broken rock is constant during the process of bearing deformation test, at the end of test, the content of broken rock ( particle size is smaller than 15 mm) increases by 16. 76% and the content of broken rock (particle size is greater than 20 mm particle size) decreases by 16.76%. The research results are of significance for forecasting and controlling the movement and deformation of overlying strata caused by mining. [ABSTRACT FROM AUTHOR]

Objective For magnetic resonance cholangiopancreatography(MRCP),endoscopic ultrasonography(EUS)and computer tomography(CT) in the diagnosis of choledocholithiasis of meta analysis and evaluation on the diagnostic efficiency.Methods According to evidence-based medicine diagnostics experiment screening methods, retrieved from 1989 to 2016 Pubmed, OVID, Medline database and CNKI, Wan Fang database of MRCP, EUS and CT in diagnosis of choledocholithiasis.The screening of three diagnostic methods in the literature of meta analysis with related data and index respectively, with sensitivity and specificity, drew receiver operating characteristic(SROC), calculated the area under the curve(AUC) and Q* value,compared their diagnostic value.Results A total of 21 articles were screened out, including 25 groups, of which 13 groups of MRCP, 8 groups of EUS, 4 groups of CT. Meta analysis results showed that the sensitivity of MRCP, EUS, CT were 0.91, 0.95,0.83 respectively, specificity were 0.97, 0.96, 0.88; SROC AUC were 0.983 8, 0.989 7, 0.924 9, the Q* value of 0.944 7,0.957 8, 0.859 1 respectively. The sensitivity of three inspection methods had no obvious difference,but the specificity of MRCP and EUS was higher than that of CT,AUC and Q* value were higher. Conclusion Three inspection methods can be widely used in clinical, CT is a rapid diagnosis methods of choledocholithiasis, less trauma; MRCP as a noninvasive method at present, the accuracy is higher, but the testing time is long;invasive EUS accuracy is higher, to a certain extent, the result can be affected by the operator technology. [ABSTRACT FROM AUTHOR]

Objective To explore the influence of the enteral nutrition(EN) and total parenteral nutrition(TPN) on local complications in severe acute pancreatitis (SAP). Methods The clinical data of 210 patients with local complications (peripan-creatic effusion, pseudocyst) after SAP treated in our hospital from December 2005 to February 2015 were retrospectively analyzed. These cases were divided into the EN group [percutaneous endoscopic gastric/jejunum stoma (PEG/PEJ) and nasal jejunal feeding tube] and the TPN group. The nutrition situation (albumin,HGB,lymphocyte),complication outcome and mortality rate were compared between the two groups ,and the occurrence rates of 2-kind nutritional mode operation associated complications were compared too. Results Compared with the TPN group, the HGB, lymphocyte and ALB levels in the EN group were in-creased with statistical difference(P<0.05),the probability of new complication appearance and mortality rate were decreased with statistical difference (P<0.05),but the reduced and completely absorption time of different complications had no statistical differ-ences between the EN group and the TPN group(P>0.05);the occurrence rate of 2-kind EN operation related complications in the nasal jejunal tube group was increased compared with the gastric jejunal stoma group ,the difference was statistically significant(P<0.05). Conclusion The patients with local complications after SAP have fasting for a long time, an effective nutrition support is necessary. The effect of EN is obviously superior to TPN ,in which PEG/PEJ has little complications than nasal jejunal feeding tube and is suitable for clinical application. [ABSTRACT FROM AUTHOR]

A testing system MTS 815 was used to carry out triaxial compression test for Qianjiaying coal-rock combined body. The results show that the consolidation stage is shorter and it apparently has a linear elastic stage and a plastic yield stage under the influence of confining pressure. Ductility of post-peak stage is much more apparent with the increase of confining pressure. Based on the change laws of peak strain, elastic modulus, rupture angle and strength,the threshold confining pressure of deformation is 10-15 MPa. The failure mode of coal body is mainly shear failure,and some rock bodies have the same failure mode with coal body. The rupture angle is within the range of 14. 1°—38. 8° and its average value is 26. 84° which has little difference with 28. 31° calculated using Coulomb strength criterion. Residual strength has an increasing trend with the increase of confining pressure while rock Ds has the opposite trend. From 0 to 5 MPa,the decreasing range of Ds is the largest which reflects the sensibility to confining pressure. Then, with the increase of confining pressure,Ds shows a linear decrease. Finally,the values of m,s in Hoek-Brown and generalized Hoek-Brown failure criterion are discussed. [ABSTRACT FROM AUTHOR]

It has a safety significance to investigate the advance fracture of main roof and support crushing mechanism when workface crossing abandoned roadway or accessing to removal gateway. Similar simulation experiment was used to study the breaking characteristic of overlying strata，the stress on the surrounding rock and the load on the supports. Result shows that in the similar simulation of Shenhua Coal Mine，when the workface passing though the 12 m-wide roadway，the main roof was broken ahead of workface. Worse yet，the inferior key strata was broken at once and slid soon afterwards. The load exerted on the support increased from 4 000 kN to 12 500 kN then to 16 200 kN. The abutment pressure increased and moved forward. Impact of ahead distance，surrounding rock conditions and mining technology on the stability of main roof was studied by mechanical model. Result shows that with the increase of ahead distance，the working resistance increased sharply，with the increase of the height of free space or blockness，the stability of main roof structure decreased. The break of inferior key strata also leaded to working resistance increase sharply. It is better to prevent the advance fracture than increase the working resistance when it comes to maintaining the main roof's stability in a similar workface. Above all，the control technology was put forward and the effect of site application was obvious. [ABSTRACT FROM AUTHOR]