A Comparison of the Forecasting Ability of Immediate Price Impact Models

As a consequence of recent technological advances and the proliferation of algorithmic and high‐frequency trading, the cost of trading in financial markets has irrevocably changed. One important change, known as price impact, relates to how trading affects prices. Price impact represents the largest cost associated with trading. Forecasting price impact is very important as it can provide estimates of trading profits after costs and also suggest optimal execution strategies. Although several models have recently been developed which may forecast the immediate price impact of individual trades, limited work has been done to compare their relative performance. We provide a comprehensive performance evaluation of these models and test for statistically significant outperformance amongst candidate models using out‐of‐sample forecasts. We find that normalizing price impact by its average value significantly enhances the performance of traditional non‐normalized models as the normalization factor captures some of the dynamics of price impact. Copyright © 2016 John Wiley & Sons, Ltd.     

煤层冲击倾向性试验及数值模拟

冲击地压是一种特殊的矿山动力现象,而冲击倾向性是煤岩体发生冲击地压的内在因素和必要条件.对松树镇煤矿主采煤层进行冲击倾向性试验,对冲击能量指数、弹性能量指数和动态破坏时间三个煤层冲击能量指标进行分析,得出煤层无冲击倾向性.但对开采煤层数值模拟,得出深部煤层顶部最大主应力值、顶板下沉较大,需要实施一定的防治措施.这为该矿防治冲击地压提供了科学依据.     

我国环境影响评价中存在问题及其对策

介绍了国外环境影响评价的特点,分析了我国现行环境影响评价中存在的一些问题,并提出了解决对策.     

含砾岩样中切削齿冲击载荷变化规律试验

通过直径为19 mm的单齿切削含砾岩样试验,研究砾石直径、胶结强度、切削深度、切削齿后倾角等对切削齿所受冲击载荷的影响规律,分析PDC钻头钻进砾石层的损坏机制。结果表明:切削齿受到的冲击力随着砾石层胶结强度、砾石直径的增加而增大,随切削齿切削深度的增加呈指数增加;相同切削面积下,切削齿受到的冲击力随着后倾角的增大而增大;当冲击载荷大于切削齿的极限冲击强度时,切削齿将直接产生碎裂;即使冲击载荷不能达到切削齿的极限冲击强度,周而复始的冲击载荷达到切削齿的冲击韧性时,切削齿将发生冲击疲劳损坏。     

金属表面涂装类项目的环境影响评价

介绍了涂装类建设项目环境影响评价的重点,分析了产污环节和筛选评价因子,评价了污染防治措施的可行性,指出应着重注意含重金属原料的使用、涂料的性质种类和喷漆室等效排气筒的计算等问题.     

著作权法下的图书馆工作

分析了著作权法对图书馆业务工作的影响，就图书馆如何在著作权法的框架下开展工作和提供更好的服务，提出了相关建议。     

略论互联网对高校党建工作的影响及对策

互联网的发展对高校党建工作提出了新的挑战和契机。创新党建工作，利用好网络开展高校党建工作，以提高党建工作的实效性，成为当前高校党建工作的一个重要途径。本文从互联网引起高校党建工作模式的改变、互联网对高校党建工作的影响表现及互联网环境下高校党建工作的有效开展等方面，提出了相应的对策及建议。     

基于ADAMS的采掘机械工作机构设计及性能

为了有效提高采掘机械的生产效率,节约能源,设计采用了一种新型工作机构,阐述了该工作机构的工作原理、机构特点以及在设计中要解决的问题及其解决的方法,并利用ADAMS仿真软件进行运动学仿真计算。结果表明六列抡锤设计是合理的,通过仿真计算,确定主轴的最佳转速及抡锤恢复到最佳打击状态的时间,该成果对创新采掘机械工作机构具有一定的参考价值及指导意义。     

采煤对上党盆地城镇群区域环境的影响及防治对策

通过对长治市1＋6上党城镇群区域环境现状进行的全面调查分析,得出采煤对生态环境造成的影响,并从政策和技术两个层面提出了相应的防治对策。     

Surface pollen assemblages of human-disturbed vegetation and their relationship with vegetation and climate in Northeast China

Pollen assemblages of 53 surface pollen samples from farmlands and wastelands in Northeast China were analyzed. Tree pollen percentages were usually higher than 30%, with Pinus (26.9%), Quercus (0.9%), Betula (0.9%) and Populus (0.7%) as the major types, and herb pollen percentages were usually higher than 50%, with weedy Poaceae (8.7%), Chenopodiaceae (7.1%), Artemisia (1.9%) and Compositae (3.5%) as the major taxa. Thus, the pollen assemblages were consistent with the regional vegetation compositions. However, there were differences in pollen assemblages among regions, especially among different geomorphological units. For example, in the mountains, there were more types of tree pollen and higher total percentages (average 42%) than in other areas, while cereal pollen percentages were lowest (11.2%). In the hills and high plains, herbs made up more than 60% of the pollens, with cereals (average 53.6%) the dominant type. In the low plains, pollen types were similar to those in the hills and high plains, but total pollen concentrations and the proportion of Concentricystes were much higher, while cereal pollen percentages were slightly lower (average 41.6%). Pollen assemblages in different land use types also differed. For example, in farmland, cereal pollen percentages were more than 40% and Chenopodiaceae was usually less than 2.5%, while in wasteland, weedy Poaceae was usually less than 10% and Chenopodiaceae was usually higher than 25%. Total pollen concentrations in farmland (average 3909 grains/g) were much lower than in wasteland (average 15074 grains/g). Redundancy analysis revealed that pollen assemblages were significantly negatively correlated with mean annual temperature (-0.73) and July mean temperature (-0.81) and significantly positively correlated with mean annual precipitation (0.48), indicating that pollen assemblages in the artificial or human-disturbed vegetation reflect regional climate well. Comparison of pollen assemblages in different areas of northern China showed that pollen concentrations reflect the intensities of human impact to some degree. For example, pollen concentrations decrease as human impacts increase in intensity. The cereal pollen proportions in farmland differed by area. In Northeast China, cereal pollen proportions were distinctly higher than in most other areas of northern China, suggesting differences in planting habits and climate.