煤炭库存上升 动力煤价格回落

分析了近期港口、电厂电煤库存,国际煤价,国内煤炭产量,煤炭进口以及2012年第一季度动力煤炭价格运行情况,认为2012年第2季度在雨季来水良好的情况下,煤炭库存继续上升、动力煤价格上涨无望。     

锚网索喷钢筋混凝土支护在马头门施工中的应用

玉溪煤矿进风立井马头门岩石裂隙发育,断面大,服务年限长,顶板松动圈范围大,易掉顶,成形差,采用锚网索喷一次支护和双层钢筋混凝土结构二次支护的复合支护,实施效果良好可行,值得大面积推广。     

分布式能源站的能源综合利用及噪音治理

分析了广州大学城分布式能源站（简称大学城能源站）一期项目采用2×78Mw燃气-蒸汽联合循环机组的能源利用效率状况;介绍了大学城能源站能源综合利用的成效与噪音环境治理的措施,并对天然气分布式能源系统发展方向提出了合理化建议。该项目可为我国分布式能源发展积累经验,为合理利用天然气资源、提高能源利用效率及智能电网建设支撑提供示范和推动作用。     

北票油页岩化学渗透脱挥发分模型及氮元素析出预测

以北票油页岩为研究对象,通过13C NMR和TG-FTIR实验检测,研究北票油页岩碳骨架组成以及不同升温速率下的热解特性,计算北票油页岩的热解反应动力学参数,进而构建CPD模型。基于CPD模型,采用全局自由基理论方法,获得针对北票油页岩的氮元素析出预测模型。结果表明：随着热解终温的提高,油页岩中脂肪族碳化合物呈现下降趋势,与之相反,油页岩中芳香族碳化合物则呈现明显的上升趋势,表明北票油页岩在热解过程中脂肪族化合物分解产生油气组分,而一些长链烷烃组分则发生缩聚等芳构化反应,进而导致了含量的升高;北票油页岩在各升温速率下最大失重率均为18%左右,说明升温速率对于油页岩的质量损失无明显作用;北票油页岩在不同升温速率下都有4个明显的下降阶段,说明油页岩的热解失重变化主要经历了4步反应。北票油页岩氮析出过程主要分为3个阶段,随着反应过程的进行氮元素析出量呈上升趋势,在脱挥发分的初始阶段氮元素参量保持平稳,随着热解程度的加深在200 ms后,曲线开始趋于平缓,油页岩中氮元素的析出量达到最大值。     

河南省耕地与粮食变化分析及预测

河南省是我国重要的粮食生产基地,其稳定的耕地资源对粮食生产具有重要意义.本文利用河南省29年耕地资源和粮食产量数据进行分析,研究了粮食生产和耕地资源的变化特征.结果表明,随着河南省人口的不断增长,耕地资源在不断减少,其人均耕地面积也在不断下降;河南省粮食总产量和单产极不稳定,给社会经济发展和粮食安全带来了隐患.最后,建立GM(1,1)预测模型,对2010年、2015年和2020年粮食产量、人均耕地等分别进行了预测.针对预测结果,提出了稳定、提高耕地资源和粮食生产的具体建议与对策,为政府正确决策提供了科学依据.     

Random Effects Misspecification Can Have Severe Consequences for Random Effects Inference in Linear Mixed Models

There has been considerable and controversial research over the past two decades into how successfully random effects misspecification in mixed models (i.e. assuming normality for the random effects when the true distribution is non‐normal) can be diagnosed and what its impacts are on estimation and inference. However, much of this research has focused on fixed effects inference in generalised linear mixed models. In this article, motivated by the increasing number of applications of mixed models where interest is on the variance components, we study the effects of random effects misspecification on random effects inference in linear mixed models, for which there is considerably less literature. Our findings are surprising and contrary to general belief: for point estimation, maximum likelihood estimation of the variance components under misspecification is consistent, although in finite samples, both the bias and mean squared error can be substantial. For inference, we show through theory and simulation that under misspecification, standard likelihood ratio tests of truly non‐zero variance components can suffer from severely inflated type I errors, and confidence intervals for the variance components can exhibit considerable under coverage. Furthermore, neither of these problems vanish asymptotically with increasing the number of clusters or cluster size. These results have major implications for random effects inference, especially if the true random effects distribution is heavier tailed than the normal. Fortunately, simple graphical and goodness‐of‐fit measures of the random effects predictions appear to have reasonable power at detecting misspecification. We apply linear mixed models to a survey of more than 4 000 high school students within 100 schools and analyse how mathematics achievement scores vary with student attributes and across different schools. The application demonstrates the sensitivity of mixed model inference to the true but unknown random effects distribution.     

“北斗”救生终端海上自适应功率退避算法

受海况、浸水、结冰、对星等因素影响，飞行员海上遇险后报位可靠性较低，工作时长较短。为此，提出一种自适应功率退避方法，在对报位影响因素分析基础上，利用深度神经网络，通过对经纬度、高度、俯仰角、方向、加速度、速度、浸水、信号、电量等多维度数据进行学习，拟合出覆冰、浪涌、液面等信号特征与环境特征联想模型，自适应控制信号发射时机，实现功耗的有效控制。试验表明，该方法将通信成功率及工作时长分别由36.3%、6.0 h提升至73.3%、8.6 h。     

Exploring the effect of buyer engagement on green product innovation: Empirical evidence from manufacturers

In this study, we are interested in how export firms organize knowledge management and increase product innovation performance. Prior studies have concluded that knowledge transfer from external actors leads to operational performance outcomes; others have questioned the positive influence of buyer-driven knowledge transfer activities on innovation performance. Drawing on absorptive capacity, we aim to offer a better understanding, how export firms as recipients of knowledge resources, organize their internal capabilities in order to realize firm-level product innovation. This empirical study examines the interplay of buyer-driven knowledge activities, resource acquisition and combining, and product innovation outcomes in the context of Pakistani export firms. Drawing on survey data from 239 export-manufacturing firms, we test hypotheses using structural equation modeling. Our findings show that buyer-driven knowledge transfer activities play a crucial role in enhancing export firms in absorbing and combining resources that lead to product innovation. The pragmatic suggestion of the research suggests that managers look closely at developing a culture of involvement with their buyers that promotes the development of knowledge resources. The results of this study have research, policy, and managerial implications.     

基于灰灾变预测的“牛鞭效应”解决办法

简要介绍了灾变灰预测理论,并将此理论用于零售终端企业的库存控制,通过零售商的合理库存预测来减轻牛鞭效应的影响。之后给出实际案例进行了相关的研究和分析,证明灾变灰预测是减轻牛鞭效应的很好思路。     

基于CatBoost的护士离职预测研究

针对传统的离职预测算法应用于现实中高维度小样本不平衡数据集时存在准确度低、易过拟合、鲁棒性差等问题,应用梯度增强集成分类器CatBoost算法,进行类别型特征处理,利用BOHB(Bayesian Optimization and Hyperband)寻找最优参数,结合交叉验证对模型分类性能进行评估,建立分类模型并对护士离职情况进行预测。该算法采用高维小样本不平衡特征的上海部分公立医院的护士离职数据集,并与XGBoost、随机森林、支持向量机进行对比。实验结果表明,该算法准确度高,鲁棒性强,能够有效地对护士离职进行预测。