土壤污染防治法背景下的城乡绿地系统建设：趋势与对策

《中华人民共和国土壤污染防治法》的颁布标志着中国将形成完善的土壤污染防治法律体系，建立从污染土壤调查、修复、风险防控、监测到场地再利用，从环境标准到规划管理的全方位制度。生态文明制度建设的宏观背景，再加上中国土壤污染严重、规模大、修复难、成本高、周期长等特征，将导致大量污染场地转变为绿地或生态用地，最终对绿地系统的数量与规模、布局与功能、规划与管理、环境质量标准等多个维度产生实质性影响。分析这一趋势，对其影响提出预判，最终提出对策建议。     

春季石家庄市水体浮游植物群落结构调查与分析

为探索春季石家庄市水体浮游植物群落组成与结构特点,及其主要环境影响因素,对水体中浮游植物的种类组成、细胞密度、环境因子等指标进行了调查,分析了其物种优势度、多样性指数,并对各水体的浮游植物组成与环境因子进行了聚类分析和相关性分析。结果发现:在春季的石家庄市水体中,共检出浮游植物7门47属76种,以绿藻门种类最多,约占总数的39.47%,其次为硅藻和蓝藻,裸藻、金藻、黄藻和甲藻种类很少且仅在个别采样点位出现。水体中硅藻细胞密度最高,平均为1.0×10~7 cells/L,占丰度组成的61.84%,其次为绿藻和蓝藻。值得注意的是,岗南水库是所有水体中仅有的金藻丰富型水体,它的金藻细胞密度高达4.5×10~6 cells/L。物种优势度分析和多样性指数分析显示,石家庄市水体中以中度富营养型指示藻类为优势类群,基本处于中度污染水平;水体聚类分析表明,石家庄市水体的浮游植物组成受整体水环境因素影响不明显;而单环境因子数据及其与浮游植物的相关性分析表明,石家庄市水质酸化严重(pH值低于6.0),除科大牧星湖和岗南水库外,多数水体处于劣V类水平,主要超标物为pH值、总磷、总氮和COD,而这可能是导致蓝藻、绿藻等耐污性种类大量繁殖的主要因素。因此,对石家庄市水体中浮游植物群落组成与结构变化的生物学监测,是进行石家庄市地表水水质监测及生态保护的重要途径。     

新中国成立70年农村基本经营制度的历史演进与发展取向——基于农村土地制度和农业经营制度的改革联动视角

研究目的:剖析农村土地制度和农业经营制度的关系,为完善农村基本经营制度提供参考。研究方法:比较分析法、文献研究法。研究结果:新中国成立70年来,农村基本经营制度先后历经新中国成立初期的"农民所有、家庭经营"、改革开放前期的"集体所有、集体经营"到改革开放后期的"集体所有、均田承包、家庭经营",再到现阶段的"集体所有、均田承包和多元经营"4个阶段。在这个过程当中,农村基本经营制度既遵循人口与土地关系、生存与发展关系以及政府与市场关系的大逻辑,又遵循着农村土地制度的"产权逻辑"、农业经营制度的"生产逻辑"等小逻辑。研究结论:为深化农村基本经营制度变革,需加强农村土地制度与农业经营制度联动改革的制度设计,发挥要素、组织和制度的作用,发展多种形式的适度规模经营,实现小农户与现代农业发展的有机衔接。     

Distribution of residual autocorrelations for multiplicative seasonal ARMA models with uncorrelated but nonindependent error terms

In this paper, we consider portmanteau tests for testing the adequacy of multiplicative seasonal autoregressive moving‐average models under the assumption that the errors are uncorrelated but not necessarily independent. We relax the standard independence assumption on the error terms in order to extend the range of applications of the seasonal autoregressive moving‐average models. We study the asymptotic distributions of residual and normalized residual empirical autocovariances and autocorrelations under weak assumptions on noise. We establish the asymptotic behavior of the proposed statistics. A set of Monte Carlo experiments and an application to monthly mean total sunspot number are presented.     

The complexity of consumer experience formulation in the sharing economy

The study examines the complexity of the factors that influence overall perception among tourists who use peer-to-peer accommodation during their vacations. More specifically, it employs fuzzy-set Qualitative Comparative Analysis to analyse data from a sample of 712 peer-to-peer holidaymakers visiting Athens, Greece, and examines the socio-demographics of age and income along with the simple attributes of perceived risks, marketing and advertising, social aspects, and price and quality issues. The findings reveal three sufficient configurations that are able to influence the overall experience: (i) the price-quality nexus, (ii) risk perspective, and (iii) social interaction. The research also compares nonlinear analysis with the dominant parametric methods in tourism and hospitality research (regression; Cramer’s V), highlighting the suitability of the former for complexity examination. It further progresses from fit to predictive validity for the examined models, and contributes to both theoretical and methodological domains.     

Integrating corporate ownership and pension fund structures: A general equilibrium approach

This paper studies pension fund design in the context of investment in the debt and equity of a firm. We employ a general equilibrium framework to demonstrate that: (i) the asset location ‘puzzle’ is purely a partial equilibrium phenomenon, conceived in a risk neutral setting, that disappears with the introduction of sufficient risk aversion; (ii) the inability of policy makers to manage an economy with multiple firms yields a mixed equilibrium, where bonds are observed in both taxable and tax-deferred accounts; and (iii) the Pareto-efficient pension plan comprises of a defined benefit plan.     

金融稳定理事会的职能地位与运行机制分析

金融稳定理事会自2009年成立以来,在促进全球金融监管体系的改革与完善,推动国际金融监管标准的制定和执行方面开展了卓有成效的工作,现已成为在全球层面协调各国金融监管当局和国际金融监管标准制定者的重要机构。金融稳定理事会机制化运行主要表现在三个方面:义务性加大、约束力增强和授权性增加。在未来发展中,金融稳定理事会应进一步提升自身的代表性和决策机制的合法性,通过自身的影响力将国际金融机构和监管标准制定机构更紧密地联系起来,并进一步提升对成员国的影响力。     

The role of the Securities and Exchange Commission in a developing economy: Implications for IFRS

Due to the widespread adoption of IFRSs throughout the world and little research on IFRS implementation in developing countries, this study investigates the role of the Securities & Exchange Commission (SEC) regarding IFRS implementation in a developing country. Adopting a mixed methodology (39 interviews and 1647 enforcement documents); the findings have raised concerns as to the adequacy of enforcement mechanisms in implementing IFRSs in Bangladesh. More specifically, only 2.6% of enforcement actions were issued over the period of 1998 to 2010. Political connectedness is the major contributing factor for uneven enforcement activities in Bangladesh. The study also finds that inconsistencies with accounting regulatory framework (Companies Act, BSEC ordinances and IFRSs), multiple regulators, and donor agencies' influence impede the effective implementation of IFRSs. The study also provides policy implications for local and national policy makers namely, IASB, the World Bank and the IMF to rethink about the regulation of IFRSs in developing countries.     

Identifying the internal structure evolution of urban built-up land sprawl (UBLS) from a composite structure perspective: A case study of the Beijing metropolitan area,China

Differences in the internal composite structure during urban built-up land sprawl (UBLS) will generate different effects, and thus, a city’s spatial structure has important bearings on urban sustainability. This study investigates the spatial and temporal characteristics of the internal structure and allocation relationship of UBLS using multivariate spatial correlation and the Weaver-Tomas composite coefficient based on site data of granted built-up land parcels. Moreover, the composite structure evolution process of UBLS and its driving mechanism are examined in this study. The results reveal that the amount structure of the three types of UBLS (i.e. industrial land sprawl, residential land sprawl and commercial land sprawl) tended to be balanced during the study period. Following the transformation and upgrade of the urban industry structure, the overall composite structure of UBLS ranged from single residential land-use structure (Res.) to industrial-residential land-use structure (Ind.-Res.) In the early period of land marketization, the marketization land granting mechanism caused low spatial correlation between the various types of UBLS and a single composite structure, i.e. Res., single commercial land-use structure (Com.), and residential-commercial land-use structure (Res.-Com.). Subsequently, a dual-driving force including the market economy and government interventions caused a relatively high degree of spatial correlation and a multiple composite structure, i.e. Ind.-Res. and industrial-residential-commercial land-use structure (Ind.-Res.-Com.). However, the evolution characteristics of the composite structure in various regions illustrate some problems, such as the spatial isomorphism phenomenon of the composite structure and the dislocation of urban built-up land allocation. The urban internal built-up land spatial layout pattern is the embodiment of two dominant driving forces, the market and the government, interacting with each other according to natural and socioeconomic conditions. Therefore, we suggest that it is necessary to reform the future urban built-up land granting mechanism based on market guidance, and the composite structure of UBLS should be adjusted according to the regional function. The government should reinforce the macro-control of land-use planning for the dispersed granted land parcels so as to optimize the urban land-use structure.     

基于 BP 神经网络的结构损伤识别研究

针对结构的损伤识别进行了研究，选取结构固有频率平方变化比作为特征参数，建立12×25×1 BP网络结构，采用均方误差函数目标误差函数，学习函数选取梯度下降动量学习函数和L-M优化算法，对四层钢框架结构的损伤进行了检测。