软交换技术在电信公网项目建设中的应用

根据软交换及下一代网络（NGN）的技术特点,结合西藏电信公网的实际组网情况,讨论了软交换技术在本地电信网络中的应用以及本地网络智能化改造总体方案,为未来电信公网的建设提供借鉴。     

数控φ160镗床电气改造实例

结合φ160数控系统的改造过程,介绍数控系统的电气系统组成,电气结构,参数设定及相关功能实现方法。着重阐述了数控系统在改造前先期准备（包括设计,选型,安装,实验等）及调试过程中需要考虑的相关问题。     

Implementation of the NCN pathway of prompt-NO formation in the detailed reaction mechanism

This work presents revised detailed reaction mechanism for small hydrocarbons combustion with possibly full implementation of available kinetic data related to the prompt NO route via NCN. It was demonstrated that model predictions with the rate constant of reaction CH + N₂ = NCN + H measured by Vasudevan and co-workers are much higher than experimental concentrations of NO in rich premixed flames at atmospheric pressure. Analysis of the correlations of NO formation with calculated concentrations of C₂O radicals strongly supports the inclusion of reaction between C₂O and N₂ and reduction of the rate constant of reaction between CH and N₂. Rate constants of the reactions of NCN consumption were mostly taken from the works of Lin and co-workers. Some of these reactions affect calculated profiles of NCN in flames. Proposed modifications allow accurate prediction of NO formation in lean and rich flames of methane, ethylene, ethane and propane. Agreement of the experiments and the modeling was much improved as compared to the previous Release 0.5 of the Konnov mechanism. Satisfactory agreement with available measurements of NCN radicals in low pressure flames was also demonstrated.     

Laser-induced fluorescence measurements of NCN in low-pressure CH4/O2/N2 flames and its role in prompt NO formation

NCN profiles were measured for five rich and lean premixed, low-pressure methane flames using laser-induced fluorescence (LIF). A semiquantitative determination of the NCN mole fractions as a function of spatial height above the burner is made by calibrating the NCN LIF signals using highly accurate OH LIF measurements in an adjacent spectral region. The resulting calibration yields an uncertainty estimate of a factor of 3 for the absolute values, but only ±25% for the relative NCN profiles. For all flame conditions, the NCN profiles occur immediately downstream of previously measured CH profiles. In addition, high correlations are found between the peak CH and peak NCN concentrations and the peak NCN and postflame NO concentrations over all equivalence ratios. These observations are consistent with NCN being the primary product channel from the CH + N₂ reaction and the initial intermediate in the prompt NO formation. This is the first mechanistic study in hydrocarbon flames that provides such experimental evidence. The experimental profiles are compared to numerical calculations using modified versions of two well-established hydrocarbon kinetic mechanisms. Reasonable agreement between the calculations and experiment is found for NCN profile shape, location of peak NCN concentrations, and absolute mole fractions. However, the dependence on stoichiometry of the peak NCN concentration is overestimated. Further work is required on NCN kinetics for modeling prompt NO in laminar premixed flames.     

NCN concentration and interfering absorption by CH2O, NH and OH in low pressure methane/air flames with and without N2O

Absorption spectra in the wavelength region around 329 nm have been recorded with the cavity ring-down technique in various low pressure (200 hPa) CH₄/air flames, two of which with N₂O (nitrous oxide) addition. NCN (cyanonitrene) absorption appears to be significant only in N₂O-enriched flames, which also reveal spectrally nearby absorption by NH. In a φ = 1.14, N₂O oxidizer volume fraction = 57.0% flame, an upper limit for the NCN mole fraction of 4.0 × 10⁻⁶ has been found. Absorption spectra have been recorded as a function of height and these clearly show the presence of CH₂O (formaldehyde) and OH as well. In CH₄/air flames, absorption by CH₂O at and near the flame front is strong enough to mask any possible absorption signal due to NCN. OH absorption spectrally coincident with the maximum NCN absorption has been observed as well. CH₂O absorption is present throughout the whole 327–331 nm range, which can severely affect the accuracy of NCN concentration measurements if both species are present in the measurement volume. This necessitates the acquisition of continuous spectra instead of absorption measurements at a few specific wavelengths. Absorption signals at wavelengths characteristic for NCN, CH₂O, NH and OH are analysed as function of height in the flame. Probabilities that these signals may be assigned unambiguously to a single species are discussed.     

Effect of a hygienized rennet paste and a defined strain starter on proteolysis,texture and sensory properties of semi-hard goat cheese

A hygienized rennet paste (HRP) and a defined strain starter culture, including Lactobacillus casei subsp. casei IFPL as adjunct, were considered for manufacturing Majorero cheese, a Spanish traditional variety made from goat milk. Influence of both factors on physicochemical characteristics, proteolysis, rheological and sensory properties, was evaluated throughout the ripening. Cheeses produced either industrially (IL) or in artisanal manner (AL) were compared with the experimental lot (EL), which included HRP and IFPL starter in its manufacture. Results showed a low level of primary proteolysis, expressed by a low content of non-casein nitrogen (NCN), in experimental cheeses. Despite the slightly poor texture (hard and crumbly) related to the high TS and salt contents, a good general acceptability was attained for EL, with the best scores for aroma and flavour intensities achieved at 30 ripening days. In fact, the sensory panel detected the “piquant” flavour (typical of the artisanal cheese variety) in EL after 15 days of ripening.     

对IP技术发展中一些问题的思考

本文首先介绍了IP技术发展中存在的主要问题,针对IP安全问题和QoS问题提出了发展战略,尤其针对IPv6发展中的一些关键问题进行了深入探讨。     

燃气轮机燃烧室中快速型NO形成的数值计算

为数值预测燃气轮机燃烧室生成的快速型NO含量,分别采用完全NO机理GRI3. 0(其中快速型NO机理为HCN子机理)及GRI3. 0_modified(其中快速型NO机理为NCN子机理),通过计算流体力学(CFD)软件计算贫预混旋流火焰下的总NO生成,并将出口NO浓度的计算结果与实验值进行比较;然后分别采用加法和减法计算了HCN子机理及NCN子机理的快速型NO的生成。结果表明:GRI3. 0及GRI3. 0_modified均对出口NO浓度做出了准确的预测,GRI3. 0_modified的准确度比GRI3. 0高7%,这归功于后者的NCN子机理对前者的HCN子机理的替换;加法与减法的计算结果相互对应,验证了这两种方法计算快速型NO的准确性; NCN子机理的快速型NO生成速率高于HCN子机理,前者的NO出口浓度比后者高1倍,分别占各自完全NO机理生成的总NO出口浓度的17%(NCN)及10%(HCN)。     

Experimental and numerical study of the role of NCN in prompt-NO formation in low-pressure CH4-O2-N2 and C2H2-O2-N2 flames

We report an experimental and modeling study on prompt-NO formation in low-pressure (5.3 kPa) premixed flames. Special emphasis is given to the quantitative detection (and prediction) of NCN, whose role in prompt-NO formation has recently been confirmed in alkane flames. Here a rich (Φ = 1.25) CH₄-O₂-N₂ flame and rich (Φ = 1.25) and stoichiometric C₂H₂-O₂-N₂ flames have been investigated. Absolute concentration profiles of CH and NCN radicals and NO species are obtained by combining laser-induced fluorescence (LIF) and cavity ring-down spectroscopy (CRDS). Temperature profile is determined in each flame using OH and NO-LIF thermometry. Flame modeling is performed to determine the role of NCN in prompt-NO formation and to test the capacity of the present chemical mechanisms to predict some intermediate species involved in prompt-NO formation. The methane flame is modeled using GDFkin®3.0_NCN mechanism [El Bakali et al., Fuel 85 (2006), 896-909]. The acetylene flames are modeled using the Lindstedt and Skevis C/H/O mechanism [Lindstedt and Skevis, Proc. Combust. Inst. 28 (2000), 1801-1807], completed by the submechanism issued from GDFkin®3.0_NCN for nitrogen chemistry. This submechanism includes the initiation reaction CH + N₂ = NCN + H. Rate constants of NO-sensitive reactions of the submechanism are modified by taking into account the recent literature. In particular, the C₂O route could be explored thanks to a significant presence of C₂O in acetylene flames. Globally, the modified submechanism of nitrogen chemistry coupled with the two hydrocarbon mechanisms leads to a satisfying prediction of NCN and NO mole fraction profiles, even though refinements of rate constant determination is still required. The role of NCN in prompt-NO formation in acetylene flames is demonstrated.     

软交换系统信令网关的关键技术研究与设计

软交换技术是下一代网络的核心技术,其中信令网关设备是软交换系统的重要组成部分,用于解决现有七号信令网与IP网之间的无缝融合问题。本文首先介绍了软交换技术及软交换系统结构的参考模型;其次对信令网关技术作了全面的阐述,重点提出了信令网关的关键技术及选择方案;最后详细介绍了信令网关的关键技术的设计。