Net Energy Payback and CO2 Emissions from Three Midwestern Wind Farms: An Update

This paper updates a life-cycle net energy analysis and carbon dioxide emissions analysis of three Midwestern utility-scale wind systems. Both the Energy Payback Ratio (EPR) and CO₂ analysis results provide useful data for policy discussions regarding an efficient and low-carbon energy mix. The EPR is the amount of electrical energy produced for the lifetime of the power plant divided by the total amount of energy required to procure and transport the materials, build, operate, and decommission the power plants. The CO₂ analysis for each power plant was calculated from the life-cycle energy input data. A previous study also analyzed coal and nuclear fission power plants. At the time of that study, two of the three wind systems had less than a full year of generation data to project the life-cycle energy production. This study updates the analysis of three wind systems with an additional four to eight years of operating data. The EPR for the utility-scale wind systems ranges from a low of 11 for a two-turbine system in Wisconsin to 28 for a 143-turbine system in southwestern Minnesota. The EPR is 11 for coal, 25 for fission with gas centrifuge enriched uranium and 7 for gaseous diffusion enriched uranium. The normalized CO₂ emissions, in tonnes of CO₂ per GW_eh, ranges from 14 to 33 for the wind systems, 974 for coal, and 10 and 34 for nuclear fission using gas centrifuge and gaseous diffusion enriched uranium, respectively.     

龙永煤田危机矿山资源接替的几种勘探模式

通过龙永煤田现有煤矿状况调查分析发现：许多矿井已步入“花甲之年”，接近矿井服务年限。为了保障我省能源安全，应当采用有效勘探方法，方能使它们“返老还童”。研究发现危机矿山延长服务年限的几种勘探模式是：其一为扩大（延伸）勘探模式；其二为小型井田（块段）勘探模式；其三为资料分析研究模式。经探采对比发现，采用这三种勘探模式后，产生了巨大的经济效益，使一大批老矿井青春再度焕发。     

东南沿海地震活动特征量

1970年以来,东南沿海地区经历了上世纪末以来明显的第Ⅴ活跃幕(或轮回)平静和活跃时段,本文通过分析研究这两个时段地震活动在时空强上的差异性,定量提取其活动演化过程参量,为该区未来地震活动期判定提供相对定量的参考依据。     

叠前时间偏移在华北地区的应用

从应用的角度较详细地论述了三维叠前克希霍夫时间偏移的过程。在给定合理的偏移孔径下,三维叠前克希霍夫时间偏移利用均方根速度对叠前地震数据进行逐道处理,从而得到准确的归位数据。叠前时间偏移相对叠后时间偏移而言,前者能够进一步提高地下信息的成像质量及归位准确性,信噪比和分辨率也得到了改善,能够满足精细的地震资料的解释。因此,三维叠前克希霍夫时间偏移对于速度变化平缓、地下构造较复杂的地区具有广泛的应用价值。     

基于卡尔曼滤波的时间序列影像背景估计

文章将卡尔曼滤波理论应用于时间序列影像的背景估计,引入衰减记忆因子解决滤波的发散问题,最终实现了对背景信号的估计。     

考虑关断时间效应的瞬变电磁一维反演

为克服因关断时间校正而带来的误差,尝试直接对包含关断时间效应的瞬变电磁资料进行反演。正演采用将斜阶跃波离散为多个阶跃波之和的方法,反演采用经典的马奎特法。对模型试算的结果表明,采用该方法直接对斜阶跃响应进行反演,结果比较理想,计算速度也可以接受。     

时域反射技术在地学研究中的应用

综合介绍了时域反射技术在地学研究中的应用。包括时域反射仪的工作原理、测量参数(特征阻抗、介电常数、土壤含水量、土壤电导率)、时域反射探针技术以及时域反射技术在农业地质、水文地质、灾害地质等研究中的应用与进展。     

Investigating the propagation mechanism of unmodelled systematic errors on coordinate time series estimated using least squares

The propagation of unmodelled systematic errors into coordinate time series computed using least squares is investigated, to improve the understanding of unexplained signals and apparent noise in geodetic (especially GPS) coordinate time series. Such coordinate time series are invariably based on a functional model linearised using only zero and first-order terms of a (Taylor) series expansion about the approximate coordinates of the unknown point. The effect of such truncation errors is investigated through the derivation of a generalised systematic error model for the simple case of range observations from a single known reference point to a point which is assumed to be at rest by the least squares model but is in fact in motion. The systematic error function for a one pseudo-satellite two-dimensional case, designed to be as simple but as analogous to GPS positioning as possible, is quantified. It is shown that the combination of a moving reference point and unmodelled periodic displacement at the unknown point of interest, due to ocean tide loading, for example, results in an output coordinate time series containing many periodic terms when only zero and first-order expansion terms are used in the linearisation of the functional model. The amplitude, phase and period of these terms is dependent on the input amplitude, the locations of the unknown point and reference point, and the period of the reference point's motion. The dominant output signals that arise due to truncation errors match those found in coordinate time series obtained from both simulated data and real three-dimensional GPS data.