A high pressure shock tube study of n-propylbenzene oxidation and its comparison with n-butylbenzene

Ignition delay times have been measured for mixtures of n-propylbenzene in air (≈21% O₂, ≈79% N₂) at equivalence ratios of 0.29, 0.48, 0.96 and 1.92 and at reflected shock pressures of 1, 10 and 30 atm in a heated high-pressure shock tube over a wide temperature range (1000–1600 K). The effects of reflected shock pressure and of equivalence ratio on ignition delay time were determined and common trends highlighted. Simulations were carried out using the n-propylbenzene sub-mechanism contained in an n-butylbenzene reaction mechanism available in the literature. This kinetic model was improved by including pressure dependent reactions which were not in place previously and the addition of the NUI Galway C₀–C₄ sub-mechanism. These simulations showed very good agreement with the experimental data. Additionally a comparison is made with experimental data previously obtained and published for n-butylbenzene over the same range of conditions and common trends are highlighted.     

钻柱振动声波录井技术方法及应用实例

钻柱振动声波录井技术DVL（Drillstring Vibro-acoustic Logging）经过多年的室内研究和现场验证,已经取得了可喜成果,为了进一步完善其解释评价方法,该课题尚需要在现场试用中不断地深化应用研究,近期又一次开展了现场试验。简介了该技术的工作原理、配套硬件构成和无线数据传输系统的特点。结合现场应用实例．阐述了DVL技术发展最新的理论分析方法和研究成果;给出了DVL技术分析中的相关分析法和信号能量计算法;列举了频聚法、能聚法和归一化数据处理方法的理论公式和其应用方法。通过应用实例证实,依据DVL频谱图、频聚和能聚曲线、能量和相位差曲线,能有效地识别地层岩性,划分地层和油藏。同时在钻具工况的分析、辅助识别上能起到了一定的作用,为DVL技术的发展奠定了理论基础。     

Efficient Retransmission Methods in Wireless MAC Protocol for Multicast

Recent studies on reliable wireless multicast have focused on sending acknowledgement packets from all member stations to the source. Although these studies provide methods of improving the reliability, there have not been any studies on retransmission methods for wireless multicast. Multicast packets are retransmitted based on the unicast transmission rule, which retransmits until all members successfully receive the packet. In this paper, an efficient retransmission method is proposed. The retransmission lasts until the target packet delivery ratio of each member is met. Moreover, the contention window size for retransmission is adjusted based on the reception status of the previous transmission. The performance of the proposed wireless multicast is evaluated by extensive simulations.     

手机平台新应用NASA Android卫星年底升空

最近美国航空航天局NASA又在低成本太空探索中创新—推出＂PhoneSat＂计划,预备在今年晚些时候发射一系列由Google Nexus One智能手机操控的微型卫星进入太空。搭载Android操作系统的智能手机、平板电脑早已横扫电子消费产品市场。近日,Android阵营又将新添一个新成员,该成员的特殊之处在于并非在＂地上＂而是脱离了地球,在＂天上＂。     

云计算:充分发挥网络架构优势

当前,网络数据量、用户终端量的激增以及视频互动分享、设备协同、物联网等应用的蓬勃发展,使得市场和产业中需要全新的计算和服务模式。     

KKT-based iterative algorithm for beamforming in cognitive radio system

In this paper,we consider the downlink channel of multi-user multi-input single-output(MU-MISO)system in cognitive radio network,where the cognitive base station(CBS)resort to beamforming scheme to relief co-channel interference.The design criterion is to minimize the transmit power at CBS,subject to the signal-to-interference-plus-noise-ratio(SINR)constraints of cognitive users(CUs)and the interference constraints at primary users(PUs).Standard conic optimization packages can handle the problem,however,the...     

CHARACTERIZATION OF OIL SANDS MINERAL COMPONENTS AND CLAY-ORGANIC COMPLEXES

ABSTRACT

Differences in oil sands processability and extraction yields can be dependent upon many factors including the composition of the mineral components and the organic complexes that are associated with certain minerals. These mineral-organic associations help provide the bridge which leads to carry over of bitumen with the tailings as well as carry over of water and mineral matter with the product. The nature of the organic component of clay-organic complexes extracted from various streams in an oil sands recovery process is discussed in relation to the stability of both water-in-oil and oil-in-water emulsions formed. These samples have been studied with nuclear magnetic resonance (NMR), scanning electron microscopy (SEM) as veil as with other techniques such as interfacial tension measurements.     

MICROSCOPIC CHARACTERIZATION OF OIL SANDS PROCESSING EMULSIONS

ABSTRACT

Microscopic characterization of oil sands emulsions can be important in the prediction of processing characteristics and process yields in the extraction of oil from oil sands. The size distribution of the emulsion can determine how efficiently the oil can be separated from the water and by what means: mechanically or chemically. In addition, it is possible to characterize the nature of the dispersed phase by using fluorescence behaviour under an optical microscope or via x-ray analysis with a scanning electron microscope. In certain cases it is also possible to characterize the interface between the dispersed and the continuous phases. This paper presents results from our laboratory using microscopic techniques and illustrates their utility, not only for determining the morphology of these economically important emulsions, but also to characterize the composition of the interface itself.     

A jet-stirred reactor and kinetic modeling study of ethyl propanoate oxidation

A jet-stirred reactor study of ethyl propanoate, a model biodiesel molecule, has been carried out at 10 atm pressure, using 0.1% fuel at equivalence ratios of 0.3, 0.6, 1.0 and 2.0 and at temperatures in the range 750-1100 K with a constant residence time of 0.7 seconds. Concentration profiles of ethyl propanoate were measured together with those of major intermediates, ethylene, propanoic acid, methane and formaldehyde, and major products, water, carbon dioxide and carbon monoxide. This data was used to further validate a previously published detailed chemical kinetic mechanism, containing 139 species and 790 reversible reactions. It was found that this mechanism required a significant increase in the rate constant of the six-centered unimolecular elimination reaction which produces ethylene and propanoic acid in order to correctly reproduce the measured concentrations of propanoic acid. The revised mechanism was then used to re-simulate shock tube ignition delay data with good agreement observed. Rate of production and sensitivity analyses were carried out under the experimental conditions, highlighting the importance that ethylene chemistry has on the overall reactivity of the system.