东北三省能源消费、要素投入与经济增长关系研究——基于长面板和面板因果检验模型

研究生产要素在区域经济增长中的作用,特别是能源消费与经济增长关系对于国家制定区域发展和能源协调政策具有指导意义。本文利用1980年~2012年东北三省经济增长与能源消费、资本及劳动投入要素数据,在生产函数框架下,通过控制面板组内自相关和组间异方差的长面板PASE估计及面板因果检验模型,研究东北三省经济增长与能源消费和投入要素间长期均衡和短期调整关系。结果表明东北三省经济增长与能源消费和投入要素间存在长期均衡关系,资本、劳动以及能源消费的产出弹性分别为0.439,0.311,0.247,全要素能源效率呈现逻辑斯蒂曲线特征,存在能源消费到经济增长方向因果关系,最后提出了提高能源使用效率、加强能源合作、加快产业结构调整,大力发展第三产业等对策建议。

冬季供暖导致雾霾?来自华北城市面板的证据

空气污染已严重影响中国居民的生活质量,而雾霾天气尤其频发于北方冬季。本文着重考察北方冬季燃煤供暖对空气质量的影响,通过使用华北39个城市从2013年10月1日至2014年5月31日的每日面板数据,在控制气象条件与节假日的情况下,长动态面板的估计结果显示冬季供暖使空气污染加剧了约20%,占供暖期相较非供暖期大气污染物增量的约三分之二(其余约三分之一为气象因素)。进一步的断点回归显示,燃煤供暖的污染效应存在一个逐步升温加压、污染物累积的过程,并非一蹴而就。在城市供热面积保持高速增长的背景下,提高供热效率及使用清洁能源成为当务之急。

长悬臂行车道板简化分析计算

对于悬臂长度超过2.5 m的行车道板,传统的有效分布宽度概念已经不再适用。以实际工程为依托,把根据沙柯公式和巴赫公式计算出的悬臂根部弯矩与传统分布宽度计算出的弯矩进行比较,得出了该工程中采用沙柯公式的计算结果要高于传统分布宽度的计算结果。为简化分析,将悬臂端部相应的分布宽度降低同样的比例,并将该分布宽度的倒数作为车轮荷载系数,利用Midas软件对桥面板进行了计算分析。

网络搜索指数与汽车销量关系研究——基于文本挖掘的关键词获取

网络搜索数据是消费者在信息搜集和购买决策过程中真实足迹的反映,对了解消费者购买需求具有重要价值。本文运用与现有研究不同的关键词获取方法,以我国汽车市场为背景,研究网络搜索数据与销量之间的关系。首先,确定网络搜索数据的关键词,主要运用了文本挖掘技术,具体而言:1对抓取的汽车论坛文本进行Jieba分词;2利用Word2vec模型把分词结果转化为向量空间模型形式;3结合TF-IDF算法和余弦相似度算法确定关键词。然后,基于108个月的长面板数据,建立网络搜索与汽车销量的固定效应模型。最后,采取滚动窗口的方式预测最近12个月的汽车销量。实证结果显示:网络搜索与汽车销量之间存在长期均衡关系,回归模型可以解释76%的方差;网络搜索数据有助于预测我国汽车销量。

长三角地区能源消费、要素投入与经济增长关系研究——基于变系数和面板因果检验模型

深入研究能源消费及投入要素对经济增长的贡献,对于协调区域要素投入和区域经济的可持续发展具有重要意义.在生产函数框架下,利用1980-2013年长三角地区各省市经济增长与能源消费、要素投入数据,通过控制面板组内自相关、截面相关及组间异方差的变系数模型和面板因果检验模型,研究经济增长与能源消费、投入要素间长期均衡和因果关系.结果表明长三角地区经济增长与能源消费、投入要素间存在长期均衡关系,浙江省的劳动和资本的产出弹性最高,分别为0.515和0.95,江苏省的劳动产出弹性和浙江省的能源消费产出弹性为负,分别为-0.124和-0.338,表现为边际报酬递减特征.长三角地区能源消费和经济增长之间满足反馈假说,并提出提高能源使用效率、调整劳动和能源的投入结构及加大经济转型力度等对策建议.

我国城乡居民生活成本实证研究——基于SYS-GMM方法的PVAR估计

在探讨通货膨胀水平、恩格尔系数及居民生活质量影响城乡居民生活成本机制的基础上,构建并估计基于城乡二元经济的长面板模型(LPM),探讨了各变量间的静态均衡关系;此外,基于SYS-GMM方法估计了面板向量自回归模型,并通过蒙特卡洛算法模拟动态脉冲响应函数进一步研究各因素之间的动态特征。结果表明:居民生活成本、通货膨胀、恩格尔系数及生活质量之间满足长期的均衡关系;通货膨胀的上升在消弱居民的实际购买力(负收入效应)的同时,也带来了居民消费结构的变化(替代效应),旅游、文化消费支出减少而食品等基本支出增加,从而造成食品等基本品的价格上涨,又由于后者在CPI构成中占较大权重,从而导致了CPI的相对上升。可以看出,恩格尔系数的上升会导致CPI的上升,并进一步导致居民生活质量的下降及生活成本的进一步上涨。

金融发展对京津冀市场一体化的影响研究

本文利用价格法测度了京津冀市场一体化水平,发现京津冀市场一体化呈稳步提高的趋势,其中京津一体化水平最高,津冀一体化水平最低,京津冀市场一体化水平在金融危机期间有短暂的下滑趋势。本文将京津冀市场一体化指标作为被解释变量,而将金融发展作为解释变量,同时加入经济发展和对外贸易等控制变量,采用分步回归的方法检验了金融发展对京津冀市场一体化的影响,结果显示金融发展对京津冀市场一体化有正面影响,并且能够通过显著性检验。

农业“三率”视角下都市型现代农业投入产出分析——以京沪津渝为例

分析2006—2020年中国4个代表性城市的农业“三率”数据特征及其变动趋势,通过分析面板数据,对京沪津渝进行都市型现代农业投入产出研究,实证验证一产增加值的各个影响因素。研究发现:劳动生产率、农用水资源利用率和资金利用率对土地产出率有显著正向影响,一产从业人数、农林水财政支出总额和农作物播种面积对一产增加值有显著影响,其中一产从业人数为负向影响;农用能源利用率对土地产出率影响不显著,农业水资源消耗总量和一产耗能总量对一产增加值影响不显著。京沪津渝都市型现代化农业生产规模较小,农业机械推广使用程度较低,应提高土地流转,形成规模化的农业生产,并为农业机械提供配套教学服务,以此来提高都市型现代农业的产出。

自我决定VS他人促进:基于长时面板数据的运动行为对主观幸福感的影响研究

【目的/意义】可穿戴设备的普及使得个人健康的量化与管理受到越来越多的关注与重视。已有研究证实社交App中的“运动排行榜”促进了用户运动数据的提升,但这种排名竞赛形式的运动行为能在多大程度上促进用户的主观幸福感,是否存在其他影响路径仍有待探究。【方法/过程】本研究基于157位小米手环用户持续105天的长时面板运动数据,并结合人格特质从自我与他人两条路径上分析了运动行为对主观幸福感的影响。【结果/结论】研究证实了:用户的运动行为同时受到自我和他人的影响,但来自自我的影响程度更高;用户的运动行为能够提高其主观幸福感;外向型人格得分高的用户更容易受到他人的激励,从而获得更高的主观幸福感。【创新/局限】本文区分了自我与他人这两条对主观幸福感的影响路径,分析了人格特质的调节作用,并验证了游戏化排名设置对运动行为的正向促进作用,为理解智慧健康管理平台中的用户交互提供了跨层次分析工具。

新冠舆情、民众情感与城市公共交通

利用Python爬虫技术获取2020年1月1日至7月31日北京、上海、武汉等10个城市的微博和地铁客流量数据,探究了疫情爆发城市的民众情感趋势、关注话题和城市交通状况,并探讨了网络舆情与交通出行之间的关系。结果显示:民众对于疫情的态度大致经历了五个阶段,情绪状态总体偏向正面;公共交通客流量受疫情影响严重,2020年1月23日后各城市日客流量均急剧下降;地铁日客流量对民众情感的影响较为显著。

我国城乡居民的内生消费估算及预测研究——以直辖市和自治区为例

内生消费的增长趋势和规模是经济内生力量的重要体现。本文建立长面板模型,通过控制时间效应估算出直辖市和自治区城乡居民内生消费规模,并通过建立混合时间序列模型对其进行预测,结果发现:直辖市和自治区城乡居民内生消费规模整体呈现上涨趋势,但近几年有所下降;直辖市和自治区农村居民内生消费规模上涨速度比城镇居民上涨速度快,但稳定性相对较差。因此,为进一步扩大居民内生消费规模,城镇居民需要缩小收入差距和加强消费行为的引导,农村居民则需要加强消费市场的挖掘。

Influence of plate length and plate cooling rate on solidification and microstructure of A356 alloy produced by oblique plate

A356 alloy melt solidifies partially when it flows down on an oblique plate cooled from bottom by counter flowing water. Columnar dendrites are continuously formed on the plate wall. Because of the forced convection, these dendrites are sheared off into equiaxed/fragmented grains and then washed away continuously by producing semisolid slurry at plate exit. Plate cooling rate provides required extent/amount of solidification whereas plate length enables necessary shear for producing semisolid slurry of desired quality. Slurry obtained is solidified in metal mould to produce semisolid-cast billets of desired microstructure. Furthermore, semisolid-cast billets are also heat-treated to improve surface quality. Microstructures of both semisolid-cast and heat-treated billets are compared. The effects of plate length and plate cooling rate on solidification and microstructure of billets produced by using oblique plate are illustrated. Three different plate lengths（200 mm, 250 mm, 300 mm） associated with three different heat transfer coefficients（1000, 2000 and 2500 W/（m2·K）） are involved. Plate length of 250 mm with heat transfer coefficient of 2000 W/（m2·K） gives fine and globular microstructures and is the optimum as there is absolutely no possibility of sticking of slurry to plate wall.

The effect of mining face＇s direction on the observed seismic activity

A major natural hazard associated with LGOM （Legnica-Glogow Copper Mining） mining is the dynamic phenomena occurrence, physically observed as seismic tremors. Some of them generate effects in the form of relaxations or bumps. Long-term observations of the rock mass behaviour indicate that the degree of seismic hazard, and therefore also seismic activity in the LGOM area, is affected by the great depth of the copper deposit, high-strength rocks as well as the ability of rock mass to accumulate elastic energy. In this aspect, the effect of the characteristics of initial stress tensor and the orientation of considered mining panel in regards to its components must be emphasised. The primary objective of this study is to answer the question, which of the factors considered as ＂influencing＂ the dynamic phenomena occurrence in copper mines have a statistically significant effect on seismic activity and to what extent. Using the general linear model procedure, an attempt has been made to quantify the impact of different parameters, including the depth of deposit, the presence of goaf in the vicinity of operating mining panels and the direction of mining face advance, on seismic activity based on historical data from 2000 to 2010 concerned with the dynamic phenomena recorded in different mining panels in Rudna mine. The direction of mining face advance as well as the goaf situation in the vicinity of the mining panel are of the greatest interest in the case of the seismic activity in LGOM. It can be assumed that the appropriate manipulation of parameters of mining systems should ensure the safest variant of mining method under specific geological and mining conditions.

A holistic examination of the load rating design of longwall shields after more than half a century of mechanised longwall mining

It is a commonly asked question:how big should the longwall shields be? The answer is a key aspect of a longwall mining feasibility study when the consequences of inadequately rated shields are considered.This paper addresses this question based on the measured nature of the loading environment in which shields are required to operate,the various geological and geometrical controls of that environment and the various links between their load rating,a range of other relevant shield design factors and the loss event they are required to prevent a major roof collapse on the longwall face.The paper concludes that despite the tremendous advances that have been made in shield design and load rating over the past50 years,the same drivers that caused longwall miners of the past to seek improved roof control on the longwall face via the use of ever-higher rated shields,are still as relevant today.However at the current time,the limits of the largest available longwall shields have yet to be tested,therefore industry focus for the foreseeable future should possibly be in achieving the maximum level of roof control on the face via their optimum operational use rather than considering further shield rating increases and incurring the inevitable downsides in terms of capital cost and shield weight.

Passive seismic velocity tomography on longwall mining panel based on simultaneous iterative reconstructive technique (SIRT)

Mining operation, especially underground coal mining, always has the remarkable risks of ground control. Passive seismic velocity tomography based on simultaneous iterative reconstructive technique （SIRT） inversion is used to deduce the stress redistribution around the longwall mining panel. The mining-induced microseismic events were recorded by mounting an array of receivers on the surface, above the active panel. After processing and filtering the seismic data, the three-dimensional tomography images of the p-wave velocity variations by SIRT passive seismic velocity tomography were provided. To display the velocity changes on coal seam level and subsequently to infer the stress redistribution, these three-dimensional tomograms into the coal seam level were sliced. In addition, the boundary element method （BEM） was used to simulate the stress redistribution. The results show that the inferred stresses from the passive seismic tomograms are conformed to numerical models and theoretical concept of the stress redistribution around the longwall panel. In velocity tomograms, the main zones of the stress redistribution arotmd the panel, including front and side abutment pressures, and gob stress are obvious and also the movement of stress zones along the face advancement is evident. Moreover, the effect of the advance rate of the face on the stress redistribution is demonstrated in tomography images. The research result proves that the SIRT passive seismic velocity tomography has an ultimate potential for monitoring the changes of stress redistribution around the longwall mining panel continuously and subsequently to improve safety of mining operations.

Roof separation characteristics of laminated weak roof strata of longwall roadway

The roof separation was investigated in a coal mine as part of the site charac- terization of roof strata deterioration in a longwall roadway. The separation of laminated, weak roof strata was initially characterized as the maximum separation, effect of geologi- cal setting on separation and the effect of mining activities (heading development, time-dependent and longwall extraction) on separation. Then the separation process was studied, so as to answer the questions of: when the separation occurs;where the separa- tion is located and what geological setting it relates to;how large of the separation is;and how the separation propagates.

In-situ growth of silver nanostructure on quartz glass substrates

Silver nanostructure compact aggregates on the surface of quartz glass substrates were synthesized by small gold seeds with the assistance of poly vinypyrrolidone (PVP) and irradiation of fluorescent lamp. The formation mechanism of silver nanostructure was proposed. The results show that both the PVP and the light irradiation are the keys to in-situ growth of silver nanostructure on quartz glass substrates. The silver nanostructure of the substrates which finally grow up to 150 nm after 20 h irradiation exhibits irregular shape, and some of nanoparticles stack to form bilayer. A new broad band appears in the absorption spectra of the substrates due to the interparticle dipole?dipole coupling of surface plasmon resonance response of the triangular silver nanoplate particles, which red shifts 600?800 nm as the particles grow up. The substrates have an emission band centered at 400 nm on their fluorescence spectra, and the fluorescence intensity shrinks as the average size of the silver nanostructure increases. The strongest SERS signal of SERS-active substrate is fabricated after 16 h.

STUDY ON THE FRACTURE AND WEIGHTING OF MAIN ROOF UNDER COMPLICATED CONDITIONS IN LONGWALL MINING

To clarify and control the collapse and weighting of main roof in longwall mining is one of the important research problems in ground control. Based on the results of physical model experiment and field measurement, the behaviour of main roof above trapezoidal goaf or with fault is studied in this paper. The fracture and weighting of main roof above trapezoidal goaf are different from those above rectangular goaf. It depends on the mechanical relation between main roof blocks whether the plate blocks of main roof on both sides of fault simultaneously break and collapse.

Seismic analysis of a long-span continuous steel truss-arch bridge across the Yangtze River

In this paper, an FEM （Finite Element Method） model is established for the main span of the bridge, with the main box arch and suspender members modeled by beam elements, truss members by truss elements, and the orthotropic steel deck by plate elements. The natural frequencies and mode shapes are acquired by the eigen-parameter analysis. By input of a typical earthquake excitation to the bridge system, the dynamic responses of the bridge, including the displacement and accelerations of the main joints of the structure, and the seismic forces and stresses of the key members, are calculated by the structural analysis program, based on which the main laws of the seismic responses of the bridge are summarized, and the safety of the structure is evaluated.

Curling of New Concrete Pavement and Long-Term Performance

Curling results from the temperature differential across the concrete slab thickness and may induce undue stresses in newly placed slab. This study deals with the finite element （FE） analysis of curling, curling stresses, field measurement of curling on a newly built jointed plain concrete pavement, and comparison of its long-term performance using both Mechanistic-Empirical Pavement Design Guide （MEPDG） and HIPERPAVII software. The FE analysis was performed with a software program, ANSYS. The test section was modeled as a three-layer system with 300 mm concrete slab, 100 mm treated drainable base, and 150 mm lime-treated subgrade. All layers were assumed to be linear elastic. Temperature data was collected at five different depth locations across the concrete slab with digital data loggers. Curling was measured on five different days with a simple setup. The effect of temperature nonlinearities across the slab thickness was also examined. The results show that both upward and downward curling increase as the temperature differential increases. The maximum stress resulting from the combined effect of curling and traffic loading due to positive temperature differential is higher than that due to the negative temperature differential of the same magnitude. Since temperature differential has a significant influence on curling, both curling and curling stresses can be mitigated at an early age with temperature control, namely via enhanced curing. Both MEPDG and HIPERPAVII showed approximately the same performance for the PCC thickness ranging from 215 mm to 300 mm for this project. Performance prediction from HIPERPAVII is very sensitive to the change in PCC thickness less than 230 mm whereas MEPDG prediction is not as sensitive to the thickness change as with HIPERPAV 1I.