Hydroprocessing of Bio-Oils and Oxygenates to Hydrocarbons. Understanding the Reaction Routes

To produce diesel fuel from renewable organic material such as vegetable oils, it has for a number of years been known that triglycerides can be hydrogenated into linear alkanes in a refinery hydrotreating unit over conventional sulfided hydrodesulfurization catalysts. A number of new reactions occur in the hydrotreater, when a biological component is introduced, and experiments were conducted to obtain a more detailed understanding of these mechanisms. The reaction pathways were studied both in model compound tests and in real feed tests with mixtures of straight-run gas oil and rapeseed oil. In both sets of experiments, the hydrogenation of the oxygen containing compounds was observed to proceed either via a hydrodeoxygenation (HDO) route or via a decarboxylation route. The detailed pathway of the HDO route was further illuminated by studying the hydroprocessing of methyl laurate into n-dodecane. The observed reaction intermediates did not support a simple stepwise hydrogenation of the aldehyde formed after hydrogenation of the connecting oxygen in the ester. Instead, it is proposed that the aldehyde formed is enolized before further hydrogenation. The existence of an enol intermediate was further corroborated by the observation that a ketone lacking α-hydrogen (that cannot be directly enolized) had a much lower reactivity than a corresponding ketone with α-hydrogen. In real feed tests, the complete conversion of rapeseed oil into linear alkanes at mild hydrotreating conditions was demonstrated. From the gas and liquid yields, the relative rates of HDO and decarboxylation were calculated in good agreement with the observed distribution of the n-C₁₇/n-C₁₈ and n-C₂₁/n-C₂₂ formed. The hydrogen consumption associated with each route is deduced, and it was shown that hydrogen consumed in the water-gas-shift and methanization reactions may add significant hydrogen consumption to the decarboxylation route. The products formed exhibited high cetane values and low densities. The challenges of introducing triglycerides in conventional hydrotreating units are discussed. It is concluded that hydrotreating offers a robust and flexible process for converting a wide variety of alternative feedstocks into a green diesel fuel that is directly compatible with existing fuel infrastructure and engine technology.     

"Major depression: A comparison of the routes to prevention": A reply to O'Neill.

Responds to the comments by P. O'Neill (see record 2007-08996-001) on C. G. Costello's original article, "Major depression: A comparison of the routes to prevention" (see record 1986-17712-001). In his comment, O'Neill described the current author's paper as "essentially a polemic against the viability of preventive strategies for alleviating the impact of social problems on psychological well-being." O'Neill asserted that a lack of understanding of how preventive interventions really work is apparent in the hypothetical examples Costello offered. In the response presented here, Costello addresses the criticisms of his paper in their order of presentation in O'Neill's commentary. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

On Becoming a Social Housing Manager: Work Identities in an ‘Invisible’ Occupation

Social housing in Britain is managed by a large grouping of ‘housing managers’, an occupational label which is viewed as unproblematic by most housing academics, and therefore, is largely taken for granted. Urban sociologists posit that a collective identity is crucial to professional status, and hence have been sceptical of housing managers' prospects of furthering their aims collectively. The paper departs from this focus on the collective endeavours of housing management as a profession to examine how housing managers themselves create and present self-identities. Specifically, it argues that housing managers use the lack of a collective identity as an opportunity to manage the ‘spoiled identity’ of being in an ‘invisible’ and marginalised profession. In doing so, they construct individualised occupational trajectories which bear little relation to the domain professionalism of more established occupations.     

2,3,5,6-四氯-4-甲基苯腈生产工艺研究

2,3,5,6-四氯-4-甲基苯腈是一种新型的杀菌剂,可用于合成液晶材料、药物、染料和其他工业制品,有巨大的市场发展前景。2,3,5,6-四氯-4-甲基苯腈是带有吸电子基的甲苯衍生物,可以由对甲基苯腈经过氯化而合成。经过反复实践研究出了一条反应条件温和,易于实现工业化生产的工艺路线。     

基于无连接传输模式的选路算法

文中借鉴通信中面向无连接传输模式的思路,构建了一个求解最佳路径的虚拟网络,使信息在虚拟网络中交互,自动探索最佳路径。并详细描述了虚拟网络的结构,给出了通信网和公交网两个求解实例。最后,通过计算复杂度分析,用文中所述算法与通用的Dijkstra算法进行比较,验证算法的计算速度。     

Refining the grain: using resident-based walkability audits to better understand walkable urban form

Researchers use measures of street connectivity to assess neighborhood walkability, and many studies show a relationship between neighborhood design and walking activity. Yet, the core connectivity measures are based on constructs designed for analyzing automobile mobility – the street network – not pedestrian movement. This article examines the effect of a finer-grained characterization of street connectivity and illustrates the idea using parent ratings of street and intersection walkability for children throughout a suburban school district in Oregon. Several policy and practice recommendations are presented, including a discussion that extends Michael Southworth’s foundational representation of streets and the walkable city using a refined, more pedestrian-centered approach to visualizing connectivity and walkable urban form.     

信息技术背景下移动学习提高学生时空应用能力路径探讨

移动学习引发了又一次学习革命,必将促进学习的泛在化和终身化。移动学习以其自身的特点天然成为外语辅助教学的最佳手段,它具有情境多样化,时空泛在化,操作便捷化,学习个性化和协作化的特性。通过教学实践提出了提高学生外语应用能力的多种路径,并构建了以自主学习、协作学习为特征的外语教学时空域。     

基于数值模拟的矿并火灾疏散路径选取研究

针对矿井火灾中人员疏散比较困难的问题,本文通过对某矿发生矿井火灾后的情景进行数值模拟,利用FDS软件分析巷道中烟气蔓延的情况、CO浓度的变化以及人员能见度的变化情况等对人员安全疏散的影响,模拟烟气动态的流动情况,从而在错综复杂的矿井巷道中选取可以安全疏散的有效路径,对于普通的通风状态无法安全疏散的情况,可以通过采用反风的方式来阻挡烟气对于可疏散路径的影响,确保人员的安全疏散.     

机载预警雷达协同探测航线优化

单架机载预警雷达探测目标时存在空域覆盖盲区和多普勒盲区。建立了巡逻航线的参数化模型,推导了机载预警雷达目标发现概率计算模型;提出了基于累积发现概率矩阵2-范数的单架机载预警雷达巡逻航线优化准则。由于多架机协同可以减小盲区对探测性能的影响,进一步研究了多架机协同探测的任务航线规划问题,提出了优化准则,分析了机载预警雷达之间的飞行时间间隔和航线之间的距离间隔对重点监视区域累积发现概率的影响。仿真结果表明了基于累积发现概率矩阵2-范数的优化准则的有效性,有利于最大化机载预警雷达空域覆盖和目标发现概率。     

通信电源后备系统的设计

介绍一种新颖的通信电源后备系统，该系统能在恶劣环境下可靠工作，在正常供电情况下以理想的充电曲线向电瓶充电，当交流供电不正常时自动切换到电瓶供电状态。系统主要由UC2906，VI-26L-CU和外围电路组成，目前该系统已经应用于直放机电源中，长期工作运行表明该系统可靠性高，性能优良。