Experimental and chemical kinetic modeling study of small methyl esters oxidation: Methyl (E)-2-butenoate and methyl butanoate

This study examines the effect of unsaturation on the combustion of fatty acid methyl esters (FAME). New experimental results were obtained for the oxidation of methyl (E)-2-butenoate (MC, unsaturated C₄ FAME) and methyl butanoate (MB, saturated C₄ FAME) in a jet-stirred reactor (JSR) at atmospheric pressure under dilute conditions over the temperature range 850-1400 K, and two equivalence ratios (Φ=0.375,0.75) with a residence time of 0.07 s. The results consist of concentration profiles of the reactants, stable intermediates, and final products, measured by probe sampling followed by on-line and off-line gas chromatography analyses. The oxidation of MC and MB in the JSR and under counterflow diffusion flame conditions was modeled using a new detailed chemical kinetic reaction mechanism (301 species and 1516 reactions) derived from previous schemes proposed in the literature. The laminar counterflow flame and JSR (for ?=1.13) experimental results used were from a previous study on the comparison of the combustion of both compounds. Sensitivity analyses and reaction path analyses, based on rates of reaction, were used to interpret the results. The data and the model show that MC has reaction pathways analogous to that of MB under the present conditions. The model of MC oxidation provides a better understanding of the effect of the ester function on combustion, and the effect of unsaturation on the combustion of fatty acid methyl ester compounds typically found in biodiesel.     

湘钢预应力钢丝用钢SWRH82B盘条的质量控制

湘钢采用铁水预处理-80t顶底复吹转炉-90 t LF-150 mm ×150 mm方坯连铸机-高速线材轧机成功开发出Φ11~13mm的预应力钢丝和钢绞线用钢SWRH82B(%:0.79~0.83C,0.70~0.80Mn,0.17~0.22Cr,≤0.020S,≤0.025P)盘条。实践表明,中间包钢水过热度控制在15~25(30)℃,拉坯速度2.6~2.9m/min,拉坯速度波动值≤0.2m/min,二冷水量1.95~2.10L/kg,可使铸坯中心碳偏析比(铸坯中心碳含量/钢水碳含量)≤1.04,盘条索氏体率≥85%,实际拉拔和捻股过程中10⁴m的断丝率≤1次。     

The Gernsheim Collection

This article focuses on the photographs of public sculptures used on belle époque picture postcards of Brussels. The subject is approached from two perspectives. Firstly, we analyse the conventions of in situ photography of public sculpture in light of the genre’s reliance on painterly and photographic traditions, as well as its adoption of visual strategies derived from amateur and snapshot photography. Secondly, we explore the role of the photographic mise-en-scène of picture postcards in constructing an ideological as well as visual perspective on public monuments and the cityscape. The in situ photography of urban statues for picture postcards can be regarded as a photographic genre at the intersection of documentary art reproduction practices and amateur photography of the city. Moreover, the picture postcards discussed in this essay confirm and propagate dominant discourses on the monument and the cityscape, even if at the same time such visions were challenged. In the case of Brussels, the postcards demonstrate a preference for a monumental, impressive cityscape, worthy of representing the Belgian nation and capable of legitimising it through views of sculpture as a grand art, serving the worship of grands hommes.     

基于GAL的89C52串口扩展电路设计

本文介绍了一种通过GAL可编程芯片替代传统的逻辑芯片。扩展89C52单片机串行通讯接口的方法。给出了通过在Protel99SE嵌套的PLD99的开发环境下,对可编程逻辑器件设计的实现过程,并且将这种方法应用到实际工作。通过对GALl6V8芯片进行编程,成功的解决了一台计算机对三台现场仪表采样数据不定期发送串口数据的收集问题;采用定时芯片Intel82C53,为三路串口扩展芯片Intel82C51A提供时基。可以实现输入的三路串口数据采用各自的波特率。通过对CPU芯片的编程。实现了通讯功能。通过实际测试,可以达到预期效果,数据传输稳定、可靠。     

惯性仪表数据采集的一种实现方法

惯性仪表(陀螺仪和加速度计)是惯性导航系统中的核心部件。为便于导航计算机的数字处理．惯性仪表输出的信号通常要经过A／D或V／F转换。本文介绍惯性仪表输出信号经V／F转换后的信号处理方法，即陀螺仪和加速度计的输出经过V／F转换变成频率信号以后利用82C54构成的电路将其转化成具有一定脉冲当量的脉冲信号供计算机处理，按这种方法处理，计算机对惯性仪表的数据采集就转化为对脉冲信号的计数。文中从硬、软件两个方面讨论了这一设计与实现的方法。     

Accounting for migration in regional occupational employment projections

Occupational employment projections are one of the primary products produced by state labor market information agencies to assist with state and regional job training and worker assistance programs. In theory, the information from occupational employment forecasts should improve both interregional and intertemporal labor market efficiency through better matching between training efforts and job openings. Until recently, the projections methodology was predominantly a demand-requirements approach that failed to incorporate important labor supply effects and interstate/interregional dependencies. Recent research has focused on improving the labor supply specification. This paper reports on one such effort to evaluate the importance of interstate occupational migration and to develop methods to incorporate migration into the existing projections methodology. Initial results indicate that the total number of estimated job openings by occupation have to be revised significantly upwards when migration is taken into account.     

Numerical studies on air flow around a cube

In this paper, air approach flow moving towards a cube will be studied using computational fluid dynamics (CFD). The Reynolds Averaging of Navier-Stokes (RANS) equation types of k-ε turbulence model are used. Some RANS predicted results are compared with different upstream air speeds. Flow separation at the corner above the top of the cube, level of separation and reattachment are investigated. Reference is made to the experimental data on wind tunnels reported in the literature.A method similar to ‘recirculation bubble promoter’ is used for different approach flow speed distributions. Problems encountered in numerical simulations due to the sharp corner are discussed with a view to obtaining better prediction on recirculation flow in regions above the top of the cube. Correlations between the turbulent kinetic energy above the cube and the recirculation bubble size are derived for different distributions of approach flow speed.By limiting the longitudinal velocities in the first cell adjacent to the sharp edge of the cube or rib, and making good use of the wall functions at the intersection cells of the velocity components, positions of maximum turbulent kinetic energy and the flow separation and reattachment can be predicted by a standard k-ε model. The results agree with those obtained in the experiments.     

塔中82井区原油的特征及成因

通过对塔中I号坡折带塔中82井区原油进行地球化学分析（包括分子筛合除去正构烷烃分析）来探讨其特征和成因,结果表明：原油族组成中饱和烃占绝对优势,而饱和烃中以低碳数正构烷烃为主,C _21-/C ₂₂₊ 值达1.4~5.4,生物标志物的含量极低;甾烷C₂₇-C₂₈-C₂₉呈“V”字型分布,重排甾烷的含量较高;萜烷中三环萜的含量较高而五环萜含量极低,且三环萜以C₂₀或C₂₃为主峰;芳烃中三芳甾烷的含量很低,三芴系列化合物中硫芴含量较高;原油碳同位素较轻,其饱和烃的碳同位素值δ¹³C<-32.8‰（这些特征有别于塔东2井的寒武系原油）;原油的成熟度R_O值为0.8%左右。推断塔中82井区的原油可能并非是有机质在高成熟阶段生成的凝析油,而是中等成熟的中-上奥陶统源岩生成的正常原油在成藏后由于寒武系天然气的注入,发生了蒸发分馏作用并运移至目前的储层中再次成藏。     

基于GB3442-82的集成运放参数测试仪设计

该系统基于GB3442-82标准测量运算放大器参数的原理,以单片机和FPGA组成的最小系统为控制核心．实现了测量集成运放参数的功能。通过程控放大和精密调整放大,系统不仅完成了VIO,IIO、AVD、KCMR的测量（误差分别为1％和±2dB）,还实现了BWG的测量和自动量程转换功能,并由键盘和显示器等人机交互界面,准确显示测量信息,扩展了触摸屏控制和打印功能。     

基于89C55和82C54的光子计数仪的设计

介绍了82C54的基本功能和内部结构,控制寄存器的格式,模式0:计数结束发出中断信号的具体应用.本文给出了89C55单片机控制的硬件、软件设计实例.