极化SAR旱地作物分类的后向消除特征选择研究

[目的]作物遥感分类是作物面积监测的核心问题,也是进一步开展农作物长势、产量等专题监测的前提。特征选择是作物遥感分类的关键步骤之一,能够有效提高作物遥感分类精度和效率。文章使用后向消除的特征选择方法明确最优特征集的大小和内容,比较不同优选特征集的分类效果分析4种特征排序方法的优劣。[方法]（1）提取河北省深州市旱地作物关键生长期（6月3日、6月27日、7月21日） RADARSAT-2数据的3类特征变量共114个。（2）比较基于不同度量方式的4种特征重要性排序方法,根据特征排序结果采用后向消除方法逐步简化特征变量,确定最优特征个数,得到优选特征集。（3）比较不同优选特征集在随机森林方法下的分类效果。[结果]特征排序方法中极限树的效果最好。使用极限树算法优选的特征集参与随机森林分类,能用最少的特征（11个）,达到最高的精度（92.63%）。并且与全部特征（114个）的分类结果相比,总体精度只下降了1.78%。[结论]后向消除特征选择优选出的特征集能够明确最优特征个数,能够在保障分类精度的同时有效提升分类效率,优选出的特征集可为同种种植结构下的旱地作物分类提供参考。     

新创企业成长阶段与高管行为整合的匹配性:案例研究

在对新创企业的成长阶段进行划分的基础上,采取典型案例研究方法,分阶段地探讨高管行为整合与新创企业成长阶段的匹配性。研究发现:新创企业的成长在青春期阶段与高管行为整合的关系为不匹配,在调整期阶段与高管行为整合的关系需要根据企业是否具有行为整合的条件来确定,在稳定期阶段与高管行为整合的关系为匹配。     

基于时域数据的两种低阶等效拟配方法研究

基于时域数据,对两种低阶等效拟配方法—频域等效拟配法和时域等效拟配法进行了研究.首先阐述了时域数据的两种来源,并对飞行试验数据中的关键参数给出了修正公式.以某型飞机为例,以两种输入形式进行了飞行动力学仿真,将得到的时域数据进行了低阶等效拟配.两种低阶等效拟配方法的结果和理论值吻合,且低阶等效系统仿真结果和原始时域数据重合度很高,表明方法合理有效.并根据操纵输入形式对辨识结果的影响对操纵输入的选取提出了要求.     

基于遥感影像的钦州地区建成区 时空扩展特征分析

研究基于城市空间形态扩张理论和方法,以钦州市为研究对象,选用城市形态定量分析指标如扩 张面积、扩展速率指数、扩张强度指数、形状指数、分维数、紧凑度指数等,结合RS和GIS的空间分析和 统计分析研究钦州城市建成区空间形态扩展特征。以LandsatTM/ETM+影像为数据源,提取钦州市1987～ 2010年建成区信息,经分析结果表明:2000年以前钦州市以主城区扩展为主,1987～2010年主城区已经历 缓慢扩张向快速扩张阶段;2000年之后,随着钦州港区快速扩张,主城区扩张进入快速扩张阶段;2005～ 2008年主城区与钦州港区扩张均呈现缓慢;1987～2010年间,主城区和钦州港区的建成区形态较简单,且 呈现不规则的变化趋势,在建成区面积不断扩张的前提下,该时期内建成区以外部扩张为主内部填充为 辅;钦州港区从1990～2010年面积扩张以外部范围延伸为主;目前钦州市建成区发展处于中速发展向快速 发展阶段,城市空间形态发展仍将趋于剧烈演化阶段。     

Deep habits and the cyclical behaviour of equilibrium unemployment and vacancies

We extend the standard textbook search and matching model by introducing deep habits in consumption. This assumption generates amplification in the response of labour market variables to technology shocks by producing endogenous countercyclical mark-ups. The cyclical fluctuations of vacancies and unemployment in our model can replicate those observed in the US data, with labour market tightness being 20 times more volatile than consumption. Vacancies display a hump-shaped response to technology shocks and the numerical simulations generate an artificial Beveridge curve that is in line with the data. Our model preserves the assumption of fully flexible wages for new hires and the calibration is consistent with the estimated elasticity of unemployment to unemployment benefits. Finally, we show that in contrast to models with exogenous mark-up shocks, the deep habits model does not require an implausible variation in the elasticity of demand to match the volatility of labour market variables, and the cyclical properties of the mark-up are in line with empirical evidence.     

论中国地方保护主义的特点和效应

地方保护主义在产品市场和资金市场上有不同的形式和特点,具有产业针对性和地区针对性。不同地区的保护程度、保护手段和保护方式也不一样。从短期和局部来看,地方保护主义是有一定益处的,但从长期和全局来看,它会导致效率的降低、分配的不公平乃至整个国家经济的衰败和没落。     

The Impact of Market Orientation on the Internationalization of Retailing Firms: Tesco in Eastern Europe

This paper investigates a Western retailer's market orientation levels in two emerging markets. We examine whether the market orientation-company performance link holds true for retailers in emerging economies, despite environmental differences. By using concepts from key studies we have assimilated a fully representative model - applied through interviews with top management from Tesco and its subsidiaries and affiliates in Hungary and Slovenia. Using this example, we find that the market orientation-business performance link is valid for Western retailers in emerging economies. Here, the retailer applied market orientation predominately through; the use of matching with suppliers of own brand goods; top management emphasis on market orientation and risk taking. Intelligence generation and dissemination was exercised via global processes such as brand review.     

Fiscal stimulus and labor market dynamics in Japan

The paper studies the effects of fiscal expansion on the Japanese labor market. First, using a structural VAR model, we find that the unemployment rate falls and employment rises following an increase in government spending. We also find that fiscal expansion affects flows in and out of unemployment. While an increase in government spending increases the job-finding rate, it reduces the separation rate. We then incorporate search and matching frictions into a standard dynamic general equilibrium model, and study whether the model can explain what we observed in data. While the model fails to predict the exact size of the impact of government spending shocks on the Japanese labor market variables, it can consistently capture the empirical pattern of responses of labor market variables to shocks.     

高职院校产学合作教育发展的现状、问题及对策

我国高职院校的产学合作教育已取得了可喜的成就，在新的发展时期也遇到了新情况、新问题。本文分析高职院校产学合作教育的模式特征，剖析当前高职院校产学合作教育发展过程中存在的问题，并提出进一步发展的对策。     

Fiscal stimuli in the form of job creation subsidies

This paper examines the effects of fiscal stimuli in the form of job creation subsidies in a DSGE model with search friction and endogenous job separation. We consider two types of job creation subsidies: a subsidy for the cost of posting vacancies and a hiring subsidy. This paper finds that the effects of job creation subsides on unemployment differ between models with and without endogenous job separation. While a positive job creation subsidy shock lowers unemployment in a model without endogenous job separation, it increases unemployment in a model with endogenous job separation. We also find that while qualitatively the effects of a vacancy cost subsidy on the economy are similar to those of a hiring subsidy, quantitatively they are different.