有线-无线网络中TFRC丢包区法算法研究

TCP-Friendly Rate Control(TFRC)是一种专门针对多媒体流在Internet中传输的拥塞控制方案,而无线环境中存在的链路质量以及切换等问题严重影响该机制的性能。本文针对此问题,提出了利用有线-无线网络的AP动态地标记分组来区分丢包,并基于此设计了适合有线-无线网络的TFRC-enhance协议。通过NS的模拟验证,相对于其他的端到端丢包区分算法,本文提出的算法准确性更高,并能取得很好的性能。

CO_2-triggered gelation for mobility control and channeling blocking during CO_2 flooding processes

CO2 flooding is regarded as an important method for enhanced oil recovery （EOR） and greenhouse gas control. However, the heterogeneity prevalently dis- tributed in reservoirs inhibits the performance of this technology. The sweep efficiency can be significantly reduced especially in the presence of ＂thief zones＂. Hence, gas channeling blocking and mobility control are important technical issues for the success of CO2 injection. Normally, crosslinked gels have the potential to block gas channels, but the gelation time control poses challenges to this method. In this study, a new method for selectively blocking CO2 channeling is proposed, which is based on a type of CO2-sensitive gel system （modified polyacry- lamide-methenamine-resorcinol gel system） to form gel in situ. A CO2-sensitive gel system is when gelation or solidification will be triggered by CO2 in the reservoir to block gas channels. The CO2-sensitivity of the gel system was demonstrated in parallel bottle tests of gel in N2 and CO2 atmospheres. Sand pack flow experiments were con- ducted to investigate the shutoff capacity of the gel system under different conditions. The injectivity of the gel system was studied via viscosity measurements. The results indi- cate that this gel system was sensitive to CO2 and had good performance of channeling blocking in porous media. Advantageous viscosity-temperature characteristics were achieved in this work. The effectiveness for EOR in heterogeneous formations based on this gel system was demonstrated using displacement tests conducted in double sand packs. The experimental results can provide guideli- nes for the deployment of theCO2-sensitive gel system for field applications.

6-(N,N-Dimethylamino)-2-naphthoylacryl Acid:a Highly Selective and Sensitive Fluorescent Sensor of Copper(Ⅱ)

A novel fluorescent probe,6-（N,N-dimethylamino）-2-naphthoylacryl acid（ACADAN） was designed and synthesized as a fluorescent sensor for Cu^2＋ in aqueous media.Significant amplification of fluorescence signals without causing any discernible change of maximum fluorescence emission wavelength（λ max） was observed upon the addition of Cu^2＋.Importantly,ACADAN is capable of recognizing Cu^2＋ selectively in aqueous media in the presence of various biologically relevant metal ions and the prevalent toxic metal ions in the environment with high sensitivity（detection limit was 0.1 μmol/L）.

Luminescent properties of thermally activated delayed fluorescence molecule with intramolecular π-π interaction between donor and acceptor

Influence of intramolecular π-π interaction on the luminescent properties of thermally activated delayed fluorescence（TADF） molecule（3, 5-bis（3,6-di-tert-butyl-9 H-carbazol-9-yl）-phenyl）（pyridin-4-yl） methanone（DTCBPY） is theoretically studied by using the density functional theory（DFT） and time-dependent density functional theory（TD-DFT）.Four conformations（named as A, B, C, and D） of the DTCBPY can be found by relax scanning, and the configuration C corresponds to the luminescent molecule detected experimentally. Besides, we calculate the proportion of each conformation by Boltzmann distribution, high configuration ratios（44% and 52%） can be found for C and D. Moreover, C and D are found to exist with an intramolecular π-π interaction between one donor and the acceptor; the intramolecular interaction brings a smaller Huang-Rhys factor and reduced reorganization energy. Our work presents a rational explanation for the experimental results and demonstrates the importance of the intramolecular π-π interaction to the photophysical properties of TADF molecules.

Enhanced adsorption behavior of Nd(III) onto D113-III resin from aqueous solution

An enhanced adsorption and desorption procedure of Nd（Ⅲ） onto D113-Ⅲ resin were prepared with various chemical methods. Batch studies were carried out with various pH, contact time, temperature and initial concentrations, and then column studies were conducted. The results showed that the optimal adsorption condition was at pH value of 6.90. The process was fast initially and arrived equilibrium within 60 h. The resin exhibited a high Nd（Ⅲ） uptake as 232.56 mg/g at 298 K. The adsorption data fitted well with pseudo-second-order kinetic model. Thermodynamic parameters were studied, which indicated that the adsorption process was spontaneous and endothermic. Thomas model was delineated here to predict the breakthrough curves based on the experimental column study data. In the elution test, 1 mol/L HCl solution could achieve a satisfactory elution rate, which indicated that D113-1/1 resin could be regenerated and reused. Finally, the IR spectroscopic technique was undertaken, and a novel adsorption mechanism was proposed.

Regulated CO adsorption by the electrode with OH^(-) repulsive property for enhancing C–C coupling

Electrochemical CO_(2) reduction driven by renewable electricity is one of the promising strategies to store sus-tainable energy as fuels.However,the selectivity of value-added multi-carbon products remains poor for further application of this process.Here,we regulate CO adsorption by forming a Nafion layer on the copper(Cu)electrode that is repulsive to OH^(-),contributing to enhanced selectivity of CO_(2) reduction to C_(2) products with the suppression of C 1 products.The operando Raman spectroscopy indicates that the local OH^(-)would adsorb on part of active sites and decrease the adsorption of CO.Therefore,the electrode with repulsive to OH^(-)can adjust the concentration of OH^(-),leading to the increased adsorption of CO and enhanced C–C coupling.This work shows that electrode design could be an effective strategy for improving the selectivity of CO_(2) reduction to multi-carbon products.

Constructing a coplanar heterojunction through enhancedπ-πconjugation in g-C_(3)N_(4)for efficient solar-driven water splitting

Adjusting the electronic structure of graphitic carbon nitride(g-C_(3)N_(4))photocatalyst throughπ-πconju-gation is an effective method to achieve efficient photogenerated carrier separation.One key challenge ofπ-πconjugation control is to tune the degree of such conjugation without destroying the g-C_(3)N_(4)struc-ture.Herein we report a conceptual design that achieves a coplanar heterojunction by enhancing theπ-πconjugation via the doping of crystalline g-C_(3)N_(4)using a conjugated double bond ring molecule,1,3,5-benzenetriol,during calcination process.The selection of the dopant enables the facile creation of a unique coplanar heterojunction which not only retains the pristine network structure of g-C_(3)N_(4),but remarkably promotes separation and transfer of photogenerated carriers through the enhancedπ-conjugated endogenous electric field.As a result,the new g-C_(3)N_(4)photocatalyst efficiently photocatalyti-cally produces hydrogen from water under visible light irradiation with a high H 2 production rate up to 94.94μmol/h,and a notable external quantum efficiency of 16.4%at 420 nm.

磁共振延迟强化在肥厚型心肌病中的临床应用价值研究

目的:探讨3.0T心脏磁共振成像(CMRI)延迟强化(LGE)序列对肥厚型心肌病(HCM)的诊断价值。方法:搜集2014年1月-2016年7月在华西医院确诊为HCM的121例患者的临床资料和CMR图像。将患者的临床资料包括性别、年龄,有无心悸、胸闷、胸痛、呼吸困难、晕厥和心脏杂音及纽约心功能分级(NYHA)等纳入分析。采用心脏功能分析软件对CMRI图像进行后处理,测量左心室壁最大厚度(LVMWT)、左、右心室舒张末期容积(EDV)、收缩末期容积(ESV)、射血分数(EF)、每搏输出量(SV)和左心室心肌质量(LVMM)。根据美国心脏病协会左室壁17节段分析方法,对121例患者的2057个心肌节段进行评价。比较有LGE组和无LGE组的临床资料及CMRI参数的差异,评价LGE节段数与LVMWT和心功能分级的相关性。结果:121例HCM患者中LGE(+)91例(75.2%)共456个节段(456/2057);LGE(+)最常见于节段2和8,分别占11.6%(53/456)和11.4%(52/456)。LGE形态:表现为局限性强化70例(70/91),弥漫性强化21例(21/91)。LGE(+)组较LGE(-)组患者的年龄偏小[分别为(48.59±14.80)和(58.93±12.79)岁]、胸痛症状出现率更低(分别为22.0%和27.3%)、LVMWT值更大[分别为(2.42±0.64)和(2.05±0.37)cm],差异均有统计学意义(P<0.05)。LGE(+)节段数与LVMWT、NYHA、LVMM和LVESV均呈正相关(r值分别为0.437、0.544、0.267和0.245,P值分别为0.000、0.000、0.003和0.007),与患者年龄、LVEF和RVEF呈负相关(r值分别为-0.231、-0.244和-0.184,P值分别为0.011、0.007和0.043)。结论:3.0T心脏MRI有助于HCM患者的诊断和心功能的评估。

函数增强型神经网络应用于钢的冷弯性能研究

函数增强型神经网络（FunctionalEnhancedNet，简称FEN）是一种无隐含层的新型网络，作者应用其三阶联合激励增强特性对钢的冷弯性能进行判别研究，识别准确率近100％．对预测集的每一个输入信号添加噪音干扰，发现依然能准确判别．网络误差下降随着添加噪音的增大而逐渐变慢，可见该网络的容错能力令人满意．

Dissipative particle dynamics simulation of wettability alternation phenomena in the chemical flooding process

Wettability alternation phenomena is considered one of the most important enhanced oil recovery （EOR） mechanisms in the chemical flooding process and induced by the adsorption of surfactant on the rock surface. These phenomena are studied by a mesoscopic method named as dissipative particle dynamics （DPD）. Both the alteration phenomena of water-wet to oil-wet and that of oil-wet to water-wet are simulated based on reasonable definition of interaction parameters between beads. The wetting hysteresis phenomenon and the process of oil-drops detachment from rock surfaces with different wettability are simulated by adding long-range external forces on the fluid particles. The simulation results show that, the oil drop is liable to spread on the oil-wetting surface and move in the form of liquid film flow, whereas it is likely to move as a whole on the waterwetting surface. There are the same phenomena occuring in wettability-alternated cases. The results also show that DPD method provides a feasible approach to the problems of seepage flow with physicochemical phenomena and can be used to study the mechanism of EOR of chemical flooding.

Development and analysis of a novel AF11-2 aptamer capable of enhancing the fluorescence of aflatoxin B1

Aflatoxin B1(AFB1)is one of the most common mycotoxins that threatens human health.As singlestranded oligonucleotides with high affinity and specificity,aptamers have incomparable effect on the targeted detection of AFB1.Herein,after 11 rounds of selection and analysis using a modified affinity chromatography-based SELEX strategy,the truncated 37 nt aptamer AF11-2 was successfully obtained.The aptamer shows good detection performance for AFB1,and can sensitively detect AFB1 in the range of 100-1000 nmol/L,with a detection limit of 42 nmol/L.In the detection of pretreated edible peanut oil samples,AF11-2 aptamer also showed a high recovery rate and good stability for AFB1,and achieved satisfactory results.In addition,AF11-2 aptamer can significantly enhance the fluorescence ability of AFB1,which is not available in traditional Afla17-2-3 aptamer.After molecular docking analysis,it was found that AF11-2 and Afla17-2-3 had different nucleotide binding sites for AFB1.Afla17-2-3 binds to the carbonyl O of AFB1,while AF11-2 binds to the pyrrolic O of AFB1,which may be the main reason that AF11-2 can enhance the fluorescence of AFB1.

Photorefractive Effect in an Azobenzene Chromophore Side Groups Polymer

We have analyzed the photorefractive（PR） effect of a polymer composite was reported which combines a novel bi-functional poly（N-vinyl）-3-[p-nitrophenylazo]carbazolyl（PVNPAK） and 2,4,7-trinitro-9-fluorenone（TNF）. PVNPAK was synthesized by a post-azo-coupling reaction, with an azo derivative as the electrooptic chromophore and carbazolyl as photoconductive moiety. The asymmetric two-beam coupling gain of 13.9 cm-1 and diffraction efficiency of 1.2% for poled polymer film fabricated using a corona poling are obtained at the wavelength of 647.1 nm, confirming photorefractivity. We interpreted this result as the orientational enhancement, in which the spatial charge field may enhance the modulated orientation of the azobenzen chromophore. It is unexpected that the photorefractive gain of 9.5 cm-1 for the unpoled polymer film also was observed without external field in two-beam coupling（TBC） experiment. This phenomenon is attributed to a light-induced orientational grating when the azobenzene groups are illuminated by polarized light.

Nucleation and epitaxy growth of high-entropy REBa_(2)Cu_(3)O_(7-δ)(RE=Y,Dy,Gd,Sm,Eu)thin films by metal organic deposition

High-entropy REBa_(2)Cu_(3)O_(7-δ)(RE=Y_(0.7)+Dy_(0.2)+Gd_(0.2)+Sm_(0.2)+Eu_(0.2))(HE-REBCO) superconducting films doped with multiple rare earth elements were successfully fabricated with thickness up to 800 nm by a trifluoroacetate-metal organic deposition(TFA-MOD).The enhanced entropy change ΔS of the HEREBCO system promotes the c-axis growth of REBCO thin film in the competition with a/b-axis growth.The microstructure and element distribution were investigated by the transmission electron microscopy(TEM) and energy dispersive spectroscopy(EDS).The results show that HE-REBCO films have a great amount of stacking defects,lattice distortions and various rare earth oxides.Furthermore,the microstrain of HE-REBCO films increases significantly compared to the undoped YBCO and(Y,Dy)BCO films.Finally,the superco nducting critical temperature(T_c^(onset)) of HE-REBCO films is about 93 K,and the in-field properties are significantly improved,especially at the temperature of about 77 K.The maximum pinning force density(F_(p,max)) of the HE-REBCO samples at 77 K is 1.7 times higher than that of the undoped YBCO films.