基于负二项回归的水上交通事故分析与预测

寻找导致船舶损伤和事故伤亡原因的可能因素和对水上交通事故趋势预测一直是水上交通事故研究的焦点.基于事故因果关系的统计数据,分析港区航道及附近水域水上交通事故的伤亡人数与事故船舶类型、事故种类、事故发生时间、事故发生地理位置等因素之间的关系,通过比较泊松和负二项两种概率分布模型回归的结果,确定负二项分布形式的事故预测模型.研究表明,基于负二项回归的水上交通事故分析与预测方法具有适用性.     

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The aims of this study were to quantify the effects of factors such as mode of exercise, body composition and training on the relationship between heart rate and physical activity energy expenditure (measured in kJ?·?min^?1) and to develop prediction equations for energy expenditure from heart rate. Regularly exercising individuals (n = 115; age 18?–?45 years, body mass 47?–?120?kg) underwent a test for maximal oxygen uptake ([Vdot]O_2max test), using incremental protocols on either a cycle ergometer or treadmill; [Vdot]O_2max ranged from 27 to 81?ml?·?kg^?1?·?min^?1. The participants then completed three steady-state exercise stages on either the treadmill (10?min) or the cycle ergometer (15?min) at 35%, 62% and 80% of [Vdot]O_2max, corresponding to 57%, 77% and 90% of maximal heart rate. Heart rate and respiratory exchange ratio data were collected during each stage. A mixed-model analysis identified gender, heart rate, weight, [Vdot]_2max and age as factors that best predicted the relationship between heart rate and energy expenditure. The model (with the highest likelihood ratio) was used to estimate energy expenditure. The correlation coefficient (r) between the measured and estimated energy expenditure was 0.913. The model therefore accounted for 83.3% (R ²) of the variance in energy expenditure in this sample. Because a measure of fitness, such as [Vdot]O_2max, is not always available, a model without [Vdot]O_2max included was also fitted. The correlation coefficient between the measured energy expenditure and estimates from the mixed model without [Vdot]O_2max was 0.857. It follows that the model without a fitness measure accounted for 73.4% of the variance in energy expenditure in this sample. Based on these results, we conclude that it is possible to estimate physical activity energy expenditure from heart rate in a group of individuals with a great deal of accuracy, after adjusting for age, gender, body mass and fitness.     

短期太阳能光伏发电预测方法研究进展

提高短期光伏发电预测水平是太阳能光伏发电站并入现有电网系统和太阳能光伏开发利用的关键问题,对提高太阳能光伏发电开发利用、保证并网安全也具有重要意义.本文对国内外短期太阳能光伏发电预测方法进行了分类归纳总结,对各类方法的发展趋势、优缺点等进行了分析.结果表明,统计智能类预测方法是国内外小型光伏电站短期光伏发电量预测技术发展的重点,总体平均预测误差在3.0％～ 11.0％之间.简单物理模型类预测方法是目前国内外大中型并网光伏电站业务运行采用最多的短期光伏发电量预测方法,总体平均预测误差在5.0％～20.0％之间.复杂物理模型类预测方法是未来大型光伏电站短期发电量预测技术研究和发展应用的主要方向.文章结论对我国短期太阳能光伏发电预测技术的发展具有促进作用.     

作为预测方法的预测市场及其与德尔菲法比较研究

预测市场是兴起于20世纪90年代新的预测理论和实践,为预测和决策开辟了经济学的视角这一片新的天空。短短的10余年时间,就引起了众多领域学者的注意,并且其实践的范围迅速扩大。德尔菲法是在预测和决策中得到最广泛运用的一种方法,从其出现到现在,也只有40多年的时间。本文认为两种预测方法具有共性,但又各有特点,本文从多个方面对两种方法进行了比较：源起和背景的比较;理论基础与机制的比较;程序和方法的比较;应用范围和效果的比较。基于上述比较,本文认为,理论上而言,预测市场是一种更有效率的预测工具。     

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��[Purpose/significance] Enrich and expand the theoretical research system of building dynamic portrait of social academic App users based on small data, so as to provide ideas and reference for the social academic App platform to effectively predict the evolution trend of user behavior and improve the precise service level.[Method/process] Firstly, based on the deep analysis of concept and characteristics of the small data, combined with the feature of social academic App, this paper from two aspects of user behavior and the surface of deep factors designed dynamic portrait label system. Then collected the small data with strong correlation and high value with the user as the data support of the portrait, and clarified the acquisition and processing method. Finally, it put forward the research method to realize the dynamic portrait and form the overall frame model.[Result/conclusion] The construction of dynamic portrait of social academic App users based on small data can effectively refine the granularity of portrait, and improve the lag of previous portrait, which has important reference value for the promotion of accurate service level of social academic App platform under data-driven situation.     

档案学有向文件学发展的趋势

档案学发展至今出现了名不符实的怪现象。档案学今后的发展道路该指向何方？继承档案学传统理论精华．构建和发展文件学已经具备了一定的理论基础和实践基础．所以笔者认为档案学有向文件学发展的趋势。     

基于相空间重构方法的三维MIMO无线信道预测

第五代(5G)无线通信网络采用的大规模多输入多输出(MIMO)技术需要大量空口资源估计和反馈MIMO信道。除优化导频、估计和反馈设计外,对信道衰落的预测也是节约空口资源的有效途径。运用相空间重构方法研究三维信道模型相关的相空间重构参数,提出一种基于经验知识的小样本在线学习方法,对MIMO信道系数和信道容量进行预测。研究发现无线信道数据具有混沌性,相空间延迟时间和嵌入维数服从一定分布,因此可以作为实时预测的先验参数进行设定。实验结果表明,该方法预测效率比传统ARMA方法提升6倍左右,信道容量的平均误差最小为5.91%。最后,采用某市区的实测数据验证相空间重构方法的有效性,信道容量的预测平均误差最小为0.91%。     

新兴技术的多指标量化识别研究——基于向量表征方法的探索

[目的/意义] 立足计量视角,通过对新兴技术特征的量化评价识别“目前处于科学研究阶段、尚未完全进入产业研发落地”的新兴技术。[方法/过程] 借助Node2Vec网络表征方法,从术语共现网络中学习技术术语的向量表示;以此为基础量化新兴技术“过去、现在及未来”三大时间维度特征-“融合性、新颖性及潜在的科学影响力”,用特征值筛选技术主题是否具有新兴性,由此探索得到向量表征视角下的新兴技术识别模型。最后以航空领域为例进行实证研究,验证该方法的科学性和合理性。[结果/结论] 通过引入“术语向量表征”的计算视角,有效编码了术语实体间显性和隐性的关联关系,提升了新兴技术特征计算的客观性;同时结合技术的历史、当前和预测信息,从网络结构和语义特征两方面进行识别,取得了较好的效果。     

非语言性因素对英语听力理解的影响及对策

听力是进行交际的很重要的技能,但从四、六级考试的听力部分的情况来看,考试成绩与实际能力之间还存在很大的差距。本文着重从预测、暗示等听力策略论证了提高英语听力的办法。同时,作者还强调了文化学习、特别是本民族文化学习,树立正确的文化心态对用英语进行交际的意义。     

Technological opportunity discovery for technological convergence based on the prediction of technology knowledge flow in a citation network

As technological convergence has recently become a mainstream innovation trend, technological opportunities need to be explored in heterogeneous technology fields. Most of the previous convergence studies have taken a retrospective view in measuring the degree of convergence and monitoring the converging trends. This paper proposes a quantitative future-oriented approach to technological opportunity discovery for convergence using patent information. In a future-oriented approach, technological opportunities for convergence are suggested by predicting potential technological knowledge flows (TKFs) between heterogeneous fields. The potential TKFs are predicted by a link prediction method in a directed network, which is suggested in this paper to represent the direction of the predicted TKFs by adapting the concept of bibliographic coupling and edge-betweenness centrality. Converging technological opportunities are proposed as incremental and radical technological opportunities by extracting the potential increased knowledge flow links and emerging knowledge flow links. Moreover, the direction and themes of the predicted potential TKFs are provided as technological opportunities for convergence. As an illustration of the proposed method, the technological opportunities between biotechnology (BT) and information technology (IT) are explored. Firms and researchers can use the proposed method to seek out new technological opportunities from various technologies so that R&D policymakers can plan new R&D projects on technological convergence.