Carbon costs and benefits of France’s biomass energy production targets

Background

Concern about climate change has motivated France to reduce its reliance on fossil fuel by setting targets for increased biomass-based renewable energy production. This study quantifies the carbon costs and benefits for the French forestry sector in meeting these targets. A forest growth and harvest simulator was developed for French forests using recent forest inventory data, and the wood-use chain was reconstructed from national wood product statistics. We then projected wood production, bioenergy production, and carbon balance for three realistic intensification scenarios and a business-as-usual scenario. These intensification scenarios targeted either overstocked, harvest-delayed or currently actively managed stands.

Results

All three intensification strategies produced 11.6–12.4 million tonnes of oil equivalent per year of wood-based energy by 2026, which corresponds to the target assigned to French wood-energy to meet the EU 2020 renewable energy target. Sustaining this level past 2026 will be challenging, let alone further increasing it. Although energy production targets can be reached, the management intensification required will degrade the near-term carbon balance of the forestry sector, compared to continuing present-day management. Even for the best-performing intensification strategy, i.e., reducing the harvest diameter of actively managed stands, the carbon benefits would only become apparent after 2040. The carbon balance of a strategy putting abandoned forests back into production would only break even by 2055; the carbon balance from increasing thinning in managed but untended stands would not break even within the studied time periods, i.e. 2015–2045 and 2046–2100. Owing to the temporal dynamics in the components of the carbon balance, i.e., the biomass stock in the forest, the carbon stock in wood products, and substitution benefits, the merit order of the examined strategies varies over time.

Conclusions

No single solution was found to improve the carbon balance of the forestry sector by 2040 in a way that also met energy targets. We therefore searched for the intensification scenario that produces energy at the lowest carbon cost. Reducing rotation time of actively managed stands is slightly more efficient than targeting harvest-delayed stands, but in both cases, each unit of energy produced has a carbon cost that only turns into a benefit between 2060 and 2080.

     

同震地表位移的单站时间基线模型解算

针对强震时GPS双差相对定位精度受参考站位移的影响,而精密单点定位数据处理过程又相对复杂等问题,该文采用单站时间基线模型解算实时同震地表位移。依据短时间内对流层延迟等误差强相关和模糊度固定不变的特性,利用消电离层星间单差观测值,并对卫星钟差进行改正,建立时间基线差分解算模型。实验结果表明,本文方法所得测站位移结果与SOPAC解的互差的均方根误差在N、E、U这3个方向上分别为5.4、4.1和12.2mm,基于单站的处理方法,该文所得结果比SOPAC解更准确地反映地震期间地表运动。     

改进粒子滤波器的室内地磁匹配精度研究

针对粒子滤波算法在室内地磁分布的连续性变化中会发生滤波发散,加之算法中重采样步骤使该现象恶化,直接导致室内定位过程中目标丢失的问题。该文受Hausdorff距离度量法中点集匹配思想的启发,提出了一种利用初定位误差作为最大粒子匹配距离的约束思想,通过缩小匹配空间的区域范围的方法来解决传统算法的发散问题。最后实验表明,此方法解决了粒子滤波器在地磁匹配中出现的滤波发散现象,同时使得定位结果更加快速收敛。     

GPS RTK在异形建筑物放样中的应用

针对异形建筑物传统施工放样过程操作复杂、效率低下的问题,该文提出了采用GPS RTK进行异性建筑物施工中的放样工作。以天津市文化中心商业项目为例,利用GPS RTK技术分别对建筑物的主轴线和异形次轴线进行了放样工作,并与全站仪在放样过程和数据精度两个方面进行了对比分析,实现了异型建筑物快速、高效的施工放样。实验结果表明,GPS RTK技术不仅在放样过程中操作简单,节约资金,而且放样精度满足工程要求,相对全站仪来说具有很大优势,有助于提高复杂异形建筑物的施工放样效率。     

小波去噪的广西加权平均温度插值研究

针对广西地区探空站稀少,难以获得精确的T_m问题,GGOS atmosphere提供了利用ECMWF的相关资料计算而得到的时间分辨率为6h(UTC 00:00:00,06:00:00,12:00:00,18:00:00)、空间分辨率为2.5°×2°的全球T_m格网数据可以在没有气象数据的情况下获得较高时空分辨率的T_m,该文利用GGOS atmosphere T_m格网数据对广西地区4个探空站插值T_m,并用无线电探空数据计算的T_m检验其精度;对误差进行分析后,选取最优小波基与尺度对其残差去噪,利用去噪后得到的曲线建立T_m的改正模型。实验结果表明,插值T_m经基于小波去噪的模型改正后,其RMSE为1.29K;Bevis模型的RMSE为10.71K;GPT2_1W模型的RMSE为3.56K;改正模型精度优于传统模型,可以达到地基GPS反演GNSS-PWV的精度要求。     

自然湿地鹤类数量对土地利用变化的响应

鹤类是我国重点野生保护动物,近年来,随着人类活动的加强,鹤类数量变化显著。为了保护鹤类提供更好的依据,该文文章以升金湖自然湿地为例,研究鹤类种群数量对土地利用变化的响应。文章利用软件提取升金湖八期TM遥感影像的土地利用信息;利用土地利用动态度、物种多样性,分析土地利用变化特征及各地类生境鸟类的多样性。对比1986—2015年升金湖越冬鹤类的种群数量变化,以及土地利用变化,分析结果表明:鹤类数量与土地利用类型存在一定相关,湿地内芦苇滩地、泥滩地、草滩地、水田、建设用地等的土地类型变化,对鹤类数量影响较大。     

Improved decentralized multi-sensor navigation system for airborne applications

The integration of Global Navigation Satellite System (GNSS) and Inertial Navigation System (INS) technologies is a very useful navigation option for high-accuracy positioning in many applications. However, its performance is still limited by GNSS satellite availability and satellite geometry. To address such limitations, a non-GNSS-based positioning technology known as “Locata” is used to augment a standard GNSS/INS system. The conventional methods for multi-sensor integration can be classified as being either in the form of centralized Kalman filtering (CKF), or decentralized Kalman filtering. However, these two filtering architectures are not always ideal for real-world applications. To satisfy both accuracy and reliability requirements, these three integration algorithms—CKF, federated Kalman filtering (FKF) and an improved decentralized filtering, known as global optimal filtering (GOF)—are investigated. In principle, the GOF is derived from more information resources than the CKF and FKF algorithms. These three algorithms are implemented in a GPS/Locata/INS integrated navigation system and evaluated using data obtained from a flight test. The experimental results show that the position, velocity and attitude solution derived from the GOF-based system indicate improvements of 30, 18.4 and 20.8% over the CKF- and FKF-based systems, respectively.     

地理国情普查数据库管理系统设计

针对省级地理国情普查数据库数据海量、种类多样、更新持续、应用广泛等特征,本文提出一种集地理国情普查数据库建库、更新与应用于一体的数据库管理系统设计方案。研究在分析现有地理国情普查数据库特点的基础上,从总体设计思想、系统架构、运行模式、接口设计等几个方面进行探讨,期望为各级地理国情普查数据库管理系统建设提供借鉴。     

POS系统辅助无人机正射影像快速制作

基于INPHO软件对无人机航摄数据进行正射影像快速制作,阐述了数字正射影像图的制作流程,并对影响最终成果质量的关键环节进行了方法改进,从而总结出了快速制作无人机高质量数字正射影像图的方法和技巧。     

倾斜摄影测量技术快速获取校园实景三维模型探讨

分析了传统三维建模的弱势及不足,提出并阐述了新型基础测绘倾斜摄影测量技术的基本原理和主要特点,详细论述了利用倾斜摄影测量技术获取倾斜影像、基于倾斜影像外业像控测量及内业立体空三加密、倾斜实景三维模型数据处理及优化等技术方法。并以黑龙江工程学院校园为实际案例,介绍了利用低空倾斜手段获取校园倾斜影像、实景三维模型数据处理及成果应用,最后总结展望了倾斜实景三维模型成果应用的相关行业领域思路。