Thermodynamic investigation of methanol and dimethyl ether synthesis from CO2 Hydrogenation

The thermodynamics involved in the catalytic hydrogenation of CO₂ have been examined extensively. By assuming that methanol and dimethyl ether (DME) are the main products, two reaction systems each consisting of two pararell reactions were analyzed and compared in terms of the equilibrium yield and selectivity of the useful products, methanol and DME. The calculation results demonstrated that the production of DME allows much higher oxygenate yield and selectivity than that of methanol.     

Determination of fatty acid derivatives in fuel and diesel oil

Fuel oil plays one of the most important roles as thermal energy source in domestic application. Due to its common use, a careful monitoring of the grade and the deviation of the quality is required. Recently it has been observed that the presence of polar fatty acid derivatives is leading to problems in the fuel injection systems and consequently can cause a damage of the engine. A fast and reliably working procedure is presented, which allows the group determination of these polar compounds, namely glycerides, soaps and fatty acids. A sample preparation succeeded, which accomplishes the extraction, the clean up and the derivatization in one single reaction vessel. Derivatives were methylated with acetyl chloride and methanol and quantified with gas chromatography mass spectrometry. The complexity of fuel oil requires a careful elaboration of the clean up and the extraction procedure. Owing to the novelty of this procedure an accurate investigation and optimization of influential parameters were performed. Optimum conditions for the solid phase extraction with polar sorbents were provided for all target compounds. Additionally, the necessity of the clean up is shown with the relation between investigated analytes and matrix effects. Finally, method performance was verified with an accurate validation and analyses of spiked samples.     

高精度气体水雾含量测量方法的研究

研究了一种快速高精度测量气体中水雾含量的方法.当含有水雾的气体通过装有玻璃纤维的采样管时,多种过滤机制使水雾沉降到玻璃纤维表面,通过称量玻璃纤维滤筒的重量差,可计算出气体的水雾含量.分析结果表明:当玻璃纤维直径为5 μm时,其过滤层对水雾的收集效率大于99%;采用高纯度的玻璃纤维,可以减小其在烘箱中的失重.当玻璃纤维纯度为99.5%时,经7 h加热后,失重小于0.1 mg;玻璃纤维床层阻力和收集效率随液滴平均粒径增大而增加,对于平均粒径为1 μm 的水雾粒子,其收集效率大于99.5%.玻璃纤维过滤法比吸附法和光学法测量精度高,重复性和稳定性好,且测量结果不受环境和气体温度的影响.     

Deterministic global optimization approach to steady-state distribution gas pipeline networks

Natural gas is normally transported through a vast network of pipelines. A pipeline network is generally established either to transmit gas at high pressure from coastal supplies to regional demand points (transmission network) or to distribute gas to consumers at low pressure from the regional demand points (distribution network). In this study, the distribution network is considered. The distribution network differs from the transmission one in a number of ways. Pipes involved in a distribution network are often much smaller and the network is simpler, having no valves, compressors or nozzles. In this paper, we propose the problem of minimizing the cost of pipelines incurred by driving the gas in a distribute non-linear network under steady-state assumptions. In particular, the decision variables include the length of the pipes’ diameter, pressure drops at each node of the network, and mass flow rate at each pipeline leg. We establish a mathematical optimization model of this problem, and then present a global approach, which is based on the GOP primal-relaxed dual decomposition method presented by Visweswaran and Floudas (Global optimization in engineering design. Kluwer book series in nonconvex optimization and its applications. Kluwer, Netherlands, 1996), to the optimization model. Finally, results from application of the approach to data from gas company are presented.     

VC Management for Heterogeneous QoS Multicast Transmissions

A crucial component of the interaction between ATM's and the Internet's Quality of Service (QoS) architectures is the efficient mapping of RSVP (Resource reSerVation Protocol) as the Internet's signalling protocol onto the according ATM mechanisms. In particular, this article focuses on one of the most contrary characteristics of RSVP and ATM signalling. This is the support for heterogeneous reservations by RSVP over the ATM subnetwork, taking into account that ATM only allows for a homogeneous QoS within a single Virtual Circuit (VC). We present previous approaches to the solution of this problem and argue for more sophisticated and efficient approaches to manage ATM VCs taking into consideration ATM tariffs and resource consumption.     

浅谈大天池构造带五百梯气田水套加热炉热负荷

大天池构造带五百梯气田于1992年12月投入试采，于1997年正式投产。文章收集了五百梯气田一部分气井实际生产数据并进行计算，与原设计的计算参数及其结果作比较，总结出石炭系气藏天然气产量与流动温度的关系，并对水套加热炉热负荷进行了分析，为今后的设计提供参考。     

应用双头电导探针技术测量气液两相泡状流局部参数

本研究应用双头电导探针技术测量气泡局部参数,从而揭示了气液两相泡状流的内部流动规律。     

工程施工项目成本管控问题研究

目前建筑施工企业在其项目成本管理中存在一些不足,导致企业成本较高,直接影响到了企业的生存和发展.本文着重从战略层和策略层两个层面,提出工程施工项目成本管理的管控措施,为建筑施工企业提供建议.     

500KV变电工程造价主要影响因素分析

以30条500KV变电工程为样本,利用帕累托法对变电工程主要费用进行分析,将主要费用分解到相应专业技术指标上,然后应用SPSS软件对造价影响因素指标进行t检验和敏感性分析,从而筛选出主变总容量、无功补偿容量、高压侧出线回路数、高抗器容量4个指标为工程造价主要影响因素,并选取15个工程样本进行检验以确保结论的准确性。分析得出的变电工程造价主要影响因素,可以为电力企业管理人员合理地控制变电工程造价提供科学的方向。     

施工企业在工程施工中的签证与索赔

介绍了现场签证的工作范围和存在的问题,说明了现场签证在工程结算中的重要作用,并对如何成功索赔提出了看法,提出施工企业只有做好现场签证工作,做到成功索赔,才能获得更大的利润。