Income, Time Effects and Direct Preferences in a Multimodal Choice Context: Application of Mixed RP/SP Models with Non-Linear Utilities

Transport problems typically involve at least two types of constraints, on income and on time. Therefore, the indirect utility function depends either on the income available after having subtracted the cost of the discrete alternative and on the free time left after having worked and travelled by each competing option. In the typical linear-in-the-attributes and in-the-parameters specification, that represents the first grade approximation of the indirect utility function, the effect of income and time constraints cancel out and only the cost and time of the alternatives matter in the comparison between them. From a microeconomic point of view this is equivalent to assume that income and time effects could be disregarded; which is not always the case. To account for these effects the utility function should include second order attributes; however, in non-linear utility functions it may not be easy to distinguish among several effects that could be relevant: direct preferences for good and leisure, and simple interactions between attributes other than income and time effects. This paper analyses these effects from a theoretical point of view focusing on the possible confounding problem in detecting income and time effects. We use a dataset collected for a modal choice context and containing both revealed and stated preference data, and estimate several NL models examining the effect of the different second-order terms on detecting income and time effects. We compared specifications including square cost and time attributes, interactions between time and cost, cost divided by the income available to be spent on free time, and time multiplied by free time. Our results confirm the strong effect of direct preferences for goods and leisure time on choice, and the potential confounding effect between quadratic attributes and other non-linear omitted terms. Finally, we also found that care should be taken in highlighting income and time effects using mixed data sources, since confounding effects can occur when non-linearities are accounted for in both data sets.     

100吨转炉设备安装

针对100吨转炉设备安装过程中设备重量超载，超高，无法直接采用行车安装的情况，采用了设备分体移位吊装，现场整体组合焊接的施工工艺方案，设计专用安装工装，确保了设备安装精度并一次安装到位。     

火灾自动报警与PLC自动控制相结合在油库消防系统中的应用

为了加强对油库消防监控,更好地保护油库的消防安全,宁波镇海国家储备油库的消防监控系统尝试了火灾自动报警与PLC自动控制相结合的监控模式,并取得了良好效果,使系统监控的智能化程度大为提高,其报警及灭火控制功能更为先进。文章主要阐述了该系统的特点、结构及功能,并结合实际工程应用介绍了该系统的工作流程,为该技术在其他类似工程的应用提供了有益的借鉴。     

关于差阻式仪器的几个技术问题

本文对差阻式仪器的几个重要问题,如差阻式仪器的国家标准、监测数据的质量控制、长期埋设仪器的现场鉴定、仪器测值异常的分析处理等进行了讨论,并提出了自己的意见,供有关科研人员进一步研究和参考.     

可膨胀波纹管技术在韦15-19井的应用

可膨胀管包括可膨胀实体管和可膨胀波纹管，主要用于在不减小井眼尺寸的情况下封堵各种复杂地层，对损坏套管进行补贴修复，作为各种井筒封隔器以及延长技术套管长度。实体管和波纹管两者膨胀机理不一样，相比之下，可膨胀波纹管技术具有膨胀工艺简单，作业周期短的优点，该技术一直由俄罗斯掌握。中国石化勘探开发研究院经过多年的潜心研究，终于形成了具有自主知识产权的可膨胀波纹管产品及其配套的工艺技术，新研制的可膨胀波纹管壁厚8mm，抗内压强度35MPa，抗外挤强度10MPa，并在江苏油田韦15—19井进行了漏层封堵现场试验，经过扩眼、管串下入、水力膨胀、机械膨胀等工艺后获得圆满成功，标志着我国已经打破了国外公司对该技术的垄断，填补了国内在该领域的技术空白。     

基于GPRS的闸门监控系统设计

利用通用分组无线电业务(GPRS)通信技术、可编程逻辑控制器(PLC)和RS-485总线设计了稳定、经济的分布式闸门监控系统。该系统采用Internet/数字数据网(DDN)和GPRS Modem方式接入无线通信网络,并根据闸门监控系统的运行特点,采用GPRS实时通信与短信服务(SMS)通信相结合的方式,不仅保证了系统通信的稳定性和平衡性,且优化了系统的运行成本。最后,对基于GPRS的闸门监控系统的经济性和适用性进行了讨论。     

智能钻井电缆信号传输的研究现状及难点

目前，钻井中井下检测信号的传输主要运用泥浆脉冲、电磁波等方式。随着井深的增加、复杂结构井和欠平衡井的增多以及对传输速度要求的提高，电缆信号传输必然是今后智能钻井的发展方向。通过对半个多世纪来各类电缆信号传输的设计进行归类，详细介绍了其设计原理，提出了电缆信号传输设计的基本要求与难点。     

白云石化作用及黔桂地区泥盆系——石炭系层（块）状白云岩的成因

介绍了20世纪60年代以来国际上提出的9种主要的白云石化作用模式及机理，在此基础上对黔桂地区泥盆系—石炭系层（块）状白云岩的成因进行研究，建立了研究区研究层位中的层状白云岩储层概念模式，包括同生成岩环境中的潮坪潮汐泵汲白云石化模式，潮下海水泵汲白云石化模式，调整白云石化模式，埋藏成岩环境中的调整-压实排挤流白云石化模式，有机质参与的压实排挤流白云石化模式，以埋藏热水为主的混合白云石化模式，以埋藏热盐水为主的混合白云石化模式．以及与区域构造断裂有关的构造热液白云石化模式。     

Stable Oxygen and Carbon Isotopic Compositions of Lates stappersii Otoliths from Lake Tanganyika,East Africa

In this study, we measured growth trends in oxygen and carbon isotopic ratios in whole sagittal otoliths from three adult centropomid fish (Lates stappersii) from each of three sub-basins of Lake Tanganyika, East Africa. Sampling density was 20 to 50 samples per otolith. Both δ¹⁸O and δ¹³C values increase with age. The δ¹⁸O data suggest that otoliths were precipitated near the expected equilibrium with the ambient environment (ca. +3.5‰) and support a migration pattern from surface waters during larval stages to deeper waters (40 to 80 m) for mature fish. Relatively high δ¹⁸O values in the southern sub-basin are consistent with cooler temperatures in the region during seasonal upwelling. The δ13C increase from otolith core to edge is large (up to 4‰) and is interpreted as due to ontogenetic changes in diet and contributions from a decrease in the proportion of respired CO₂ incorporated into otolith carbonate as metabolic rates of the fish dropped with maturity. The data seem to successfully reveal life strategy and migration patterns of L. stappersii, document regional differences in lake conditions, and provide a record of temperature within the water column during which the fish lived. Higher resolution studies and analyses of historical samples could be used to constrain modern and past growth patterns, and to reconstruct past temperature gradients and productivity patterns in the lake.     

我国钢铁行业清洁生产标准HJ/T189存在的问题与修订建议

2006年10月1日起实施的《清洁生产标准钢铁行业》(HJ/T189-2006)存在着一些不足之处,如不及时修订,将无法适应“十一五”期间钢铁工业的发展形势和清洁生产形势,在某种程度上还很容易对国内钢铁企业造成误导,而且会产生一些负面不良影响。根据目前我国钢铁工业的发展形势和国内外钢铁企业已经达到的实际清洁生产水平,就其存在的问题和今后的修订谈了一些看法。