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组合断层煤层大能量矿震的前兆信息特征规律研究
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作者 王向来 王尚红 +3 位作者 张文轩 韩勇 温颖远 郭文豪 《煤炭技术》 CAS 2024年第9期138-143,共6页
屯宝煤矿WII02040501综放工作面回采期间,组合断层区域微震大能量事件频发且异常集中,为精准识别组合断层下冲击地压前兆预警信息,统计分析了工作面回采速度偏差值下有效预警时间窗范围,选取微震能量偏差值D_(e)、微震频次偏差值D_(f)... 屯宝煤矿WII02040501综放工作面回采期间,组合断层区域微震大能量事件频发且异常集中,为精准识别组合断层下冲击地压前兆预警信息,统计分析了工作面回采速度偏差值下有效预警时间窗范围,选取微震能量偏差值D_(e)、微震频次偏差值D_(f)为断层区冲击前兆异常指标,并融合断层总面积指标A(t)对WII02040501工作面进行综合预警。研究表明:工作面的微震能量和频次随断层距离接近而上升,进入断层区后指标达到峰值并保持高值异常,回采过断层后指标逐步降至正常水平,表明工作面微震事件受断层影响显著;大能量矿震发生前,D_(e)会先缓慢降低,然后突升,变化量大于70,大能量矿震当日能量偏差值均超过100;D_(f)则呈现先升高后降低的趋势,大能量矿震前3~5 d,频次偏差值出现低点临界值,临界值为0.47;A(t)在大能量前8 d内略微下降后迅速增大,表明组合断层受采动应力影响,导致断层活化,诱发了大能量矿震事件。 展开更多
关键词 组合断层 前兆预警信息 偏差值指标 预警指标
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A Correction for Classic Performance Measures
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作者 Hayette Gatfaoui 《Chinese Business Review》 2012年第1期1-28,共28页
Non-normality in asset returns is now a common feature of financial markets. However, many practitioners as well as investors do still refer to classic risk adjusted performance measures to assess their investment. Fo... Non-normality in asset returns is now a common feature of financial markets. However, many practitioners as well as investors do still refer to classic risk adjusted performance measures to assess their investment. For example, Sharpe and Treynor ratios are designed for a Gaussian world. Then, employing them for a performance assessment prospect relative to the risk borne is a biased approach. If we look for consistency in risk assessment and in asset performance valuation, we need to look for robust methods or tools. Moreover, the well-known mathematical consistency and numerical tractability concerns drive our preference for simple methods. Under this setting, we propose to account in a simple way and to some extent for the skewness and kurtosis patterns describing the deviations from normality. We adjust therefore the classic Sharpe and Treynor ratios to asymmetries in the downside and upside deviations from the mean values of asset returns. Specifically, the adjusted Sharpe and Treynor ratios are weighted by the upside and downside deviation risks. Accounting for skewness and kurtosis changes generally the ranking of hedge fund performance. Moreover, the obtained adjusted performance measures capture well the skewness and/or kurtosis patterns in hedge fund returns depending on the targeted investment strategy 展开更多
关键词 hedge fund KURTOSIS PERFORMANCE Sharpe ratio SKEWNESS Treynor ratio
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