双平行线阵的快速一维DOA估计

针对传统子空间算法需要进行特征值分解或奇异值分解等复杂计算的问题,提出一种双平行线阵（Double Parallel Linear Array,DPLA）的快速一维波达方向（Direction of Arrival,DOA）估计算法。算法通过处理互协方差矩阵的第一列元素构造出等效的噪声子空间,再通过求根MUSIC（Multiple Signal Classification）算法得到DOA估计,有效避开了特征值分解或奇异值分解,降低了计算复杂度,提高了运算速度。仿真结果表明,该算法在提高了估计精度的同时减少了估计时间。     

Ranking Crop Yield Models: A Comment

This comment discusses key specification issues that may have affected the performance and, therefore, the ranking of parametric models that were compared in a recent AJAE article. A procedure to obtain the most flexible parametric model specification possible, given the particular probability distribution function on which the model is based is presented. These specifications also allow for standardized and, therefore, more valid comparisons across parametric models that are based on different probability distributions. Finally, the comment cautions against generalization of the rankings in that AJAE article and recommends that these more flexible specifications be adopted in future comparisons and applications.     

闽江河口湿地景观生态规划

运用景观生态学原理,利用3个时期遥感影像作为基本信息源,计算景观格局指数和景观类型转移矩阵,分析和研究闽江河口湿地景观格局空间演变特征和景砚生态规划方案;研究结果表明,闽江河口淡水河流区和滨海咸水区景观格局存在空间异质性和人为干扰的程度的差异;闽江河口湿地受快速城市化的影响,湿地面临的保护与开发冲突矛盾日益凸现,从保护景观功能的角度,提出有别于自然保护小区的景观生态保护区的规划思路,将闽江河口湿地景观生态区划分为三类:湿地自然保护区、湿地景观生态保护区、湿地公园.     

呼伦贝尔草原生态功能区土地利用变化及驱动力分析

[目的]土地利用作为地球表面与人类活动连接的纽带,明确其变化特征及驱动力对于土地利用格局的优化、区域生态环境的改善和土地利用率的提高等具有重要的指导意义。[方法]文章以呼伦贝尔草原生态功能区为例,从土地利用动态度和土地利用转移矩阵来探究研究区在1990—2015年土地利用变化特征。在此基础上,运用主成分分析对研究区土地利用的年际变化进行驱动力分析。[结果]2015年草地面积为329.52万hm~2,占总面积的81.17%,是呼伦贝尔草原生态功能区的主体土地利用类型, 1990—2015年草地总量略有减少,减幅为0.04%;湿地作为研究区第二大土地利用类型,呈现先减后增、整体减少的趋势,整体减幅为0.36%;其他土地面积减少1.39万hm~2,减幅为19.05%;面积增加的土地利用类型中,耕地面积整体上呈现增加趋势,增加8 480hm~2,增幅高达102.60%;人工表面面积增加6 075hm~2,增幅为29.47%;林地面积增加了2 908hm~2,增幅10.48%。草地、湿地和其他土地利用类型表现为净转入特征,耕地、林地和人工表面用地表现为净转出特征。区域经济和农畜因素是研究区土地利用变化的主要驱动力。[结论]草地与其他土地利用类型间的相互转换是呼伦贝尔草原生态功能区土地利用变化的主要特征,区域经济和农畜因素共同影响研究区不同土地利用类型的分布。     

El Niño,La Niña,and world coffee price dynamics

Coffee is produced in equatorial and subequatorial regions of the world, which are also most affected by El Niño Southern Oscillation (ENSO). ENSO events have a tendency to amplify weather conditions such as droughts or excess precipitation in the affected regions, resulting in production shortage or excess supply, subsequently impacting agricultural commodity prices. In this research we assess effects of ENSO events on world coffee price dynamics using the monthly data between March 1989 and December 2010. We employ smooth transition autoregression framework to examine nonlinear dynamics of ENSO and coffee prices, and illustrate the results of this research using generalized impulse‐response functions. We find that ENSO events indeed have short‐term impacts on coffee prices. The research findings are of interest to coffee producers and intermediaries in the coffee markets as well as researchers in the fields of environmental and development economics.     

基于熵权与改进的TOPSIS法的蔬菜供应商评估研究

蔬菜供应链的基础上,借助于熵权与相关系数矩阵的TOPSIS法相结合的供应商评价模型。首先构建供应商的评价指标体系,然后采用熵权法得到各指标的权重,再结合实例验证该模型的可行性。结果表明该模型能够更客观地对蔬菜供应商的选择进行有效评估。     

Comparison of Hypothesis Testing and Bayesian Model Selection

The main goal of both Bayesian model selection and classical hypotheses testing is to make inferences with respect to the state of affairs in a population of interest. The main differences between both approaches are the explicit use of prior information by Bayesians, and the explicit use of null distributions by the classicists. Formalization of prior information in prior distributions is often difficult. In this paper two practical approaches (encompassing priors and training data) to specify prior distributions will be presented. The computation of null distributions is relatively easy. However, as will be illustrated, a straightforward interpretation of the resulting p-values is not always easy. Bayesian model selection can be used to compute posterior probabilities for each of a number of competing models. This provides an alternative for the currently prevalent testing of hypotheses using p-values. Both approaches will be compared and illustrated using case studies. Each case study fits in the framework of the normal linear model, that is, analysis of variance and multiple regression.     

将《预算法》修订为真正的法律

依法治国,建设社会主义法治国家,是我国法律制定与法律实施的指导思想。《预算法》的修订工作,也应围绕这一思想进行。这就意味着在《预算法》修订过程中,应该更多注重预算法的主体、预算法的法律性质以及预算法的司法性等法律问题,将《预算法》真正修订为法律。     

新型军人养老保险制度的构建及其转轨成本测算

我国现行军人养老保险是军队统筹,且保障范围狭窄、制度衔接不畅、实际养老待遇较低、财政负担过重、基金管理效率低下;为实现养老保险制度全民统筹和切实保障军人的养老权益,应构建社会统筹与个人账户相结合、辅以年金账户的新型军人养老保险制度。军人养老保险制度的转轨成本来源于当前军人养老保险制度下隐性债务的显性化,采用系统动力学模型对军人养老保险制度的转轨成本进行模拟测算,结果表明：截至2090年底转轨成本将全部显性化,“老人”和“中人”的转轨成本都呈先增后减的趋势,2035—2065年的转轨成本最高;借助社会统筹账户资金积累的缓冲和人口年龄与人口结构的变化,能够分散制度转轨带来的财务支付风险,改革不会对政府财政带来巨大压力。因此,应坚持养老保险社会统筹的改革方向,积极推进军人养老保险制度改革。     

农村宅基地流转中存在的问题与完善对策——以攸县农村宅基地流转的实地调查为例

通过结合攸县农村宅基地流转的相关调查与实际概况分析,宅基地流转方式分为出租、出售、征地置换三种。由于农村宅基地流转具有特殊性,使农村宅基地流转中存在许多问题,如流转缺乏合理的资源配置,缺乏合乎需求的法律支撑,缺乏明确的法律途径纠纷解决机制,流转缺乏灵活的宅基地利用方式以及切实可行的管理体制等。因此,必须以＂地尽其用＂作为基本出发点和总体思路,完善我国农村宅基地的流转法律制度。