中国城市公园的标度律特征分析

科学研判城市公园面积与人口规模的关系,有利于 客观认识和指导城市的可持续发展。采用1996—2019年中 国291个地级及以上城市公园面积与人口规模数据,探究二者 之间的标度关系及其标度因子的时空演化规律,进而采用基于 标度律的公园规模修正模型度量各城市公园面积达到预期值的 程度,并对规模修正指标和人均公园面积进行比较分析,得到 如下结果。1)我国公园面积与人口规模整体呈亚线性规模缩 放关系,公园具有显著规模效应,符合城市标度律特征;时间 上呈现亚线性-超线性-亚线性的阶段性波动演变特征,空间 上分异明显：华南接近线性标度关系,华中、东北、华北、西 南呈典型亚线性关系,华东、西北呈亚线性,但标度因子偏离 度较大。2)大城市在人均公园面积排序中相对靠后,在考虑 规模效应后,排名普遍提高,说明规模修正指标能在消除人口 规模影响的基础上,有效衡量不同规模城市公园面积的水平。 标度律视角下的城市公园规模测度能够为城市人口管理和公园 面积发展的决策提供科学指导,为不同规模城市公园建设提供 可借鉴的比较标准,促进公园与人口的协调发展。     

财政赤字规模应把握社会承受力限度

平衡财政赤字有举债和银行透支两个途径，二者可兼用。举债要视当期财政收入状况为前提，银行透支超越社会承受力一定限度将致发通胀。因此，必须关注财政赤字规模的社会承受力。从全国看，财政赤字规模---一定限量银行透支应以一定限量社会闲置货币资金的存在---社会承受力为依托。财政赤字宜用积极手段平衡。     

高大平房仓储粮减损增效探索

高大平房仓储粮第一年秋、冬低温季节利用小功率风机进行下行式机械通风降低基础粮温;储存稳定期在确保储存安全的前提下,进入第2年、第3年秋冬季节则采用自然通风;气温上升季节对仓房实施隔热密闭、仓顶喷淋等一系列控温措施,在低能耗的情况下,可有效控制粮温,且大大减少了因通风产生水分散失而造成的储粮损耗.经过3年的储藏,损耗率低至1.42‰,且稻谷品质达到要求,降低储粮保管费用.     

Adding Value to Applied Policy Models： The Case of the WTO and OECD Support Classification Systems

Both the OECD and the WTO have accumulated systematic data on the magnitude of support going to farmers as a result of farm policies. The datasets are collected for different purposes, but both give a detailed picture of the evolution of these policies. This paper extends recent work on the compatibility or otherwise of the two attempts at policy monitoring by considering the categorization of individual policy instruments in Norway, Switzerland, the US, and the EU. The results show how the OECD dataset, particularly with respect to the link between direct payments and production requirements, complements that of the WTO. Many payments classified in the WTO Green Box require production, raising the possibility that they may distort production and trade. Though the issue of correct notifications to the WTO is the province of lawyers, the implications for modeling and policy analysis are of interest to economists, and the broader question of improving the consistency of the two datasets is of importance in the quest for transparency in the interpretation of changes in farm policies.     

Does trade size restriction affect trading behavior? Evidence from Indian single stock futures market

Algorithmic traders use their advantage of speed to execute a large number of small-sized trades in a very short time. In the presence of a minimum trading unit (MTU) restriction, they are forced to trade at the smallest possible sizes, often restricted by the MTU. Using a novel data set of single stock futures market obtained from the National Stock Exchange of India, we show that the MTU restriction acts as a binding constraint for traders while optimizing trade sizes. Contrary to expectation, we find weak evidence that liquidity is positively impacted by the contract size revision.     

Bank credit,public financial incentives,tax financial incentives and export performance during the global financial crisis

This paper investigates the extent to which access to credit, public financial incentives and tax financial incentives affect export performance using the EU-EFIGE/Bruegel-Unicredit data set, covering firms within Austria, France, Germany, Italy, Spain, Hungary and the UK during the 2008 global financial crisis. The results show that firms receiving credit or benefiting from public financial incentives display higher export intensity and export a greater number of product lines compared to those that did not, especially in countries with better access to credit and/or financial incentives during the crisis. Further, firms benefiting from tax financial incentives show a better export performance compared to those that did not, regardless of the degree of access to credit and/or financial incentives in the country in which they operate. In addition, the effect of access to credit and public finance incentives on export performance is found to be size-dependent, while the effect of tax financial incentives is not. We suggest that governments should promote publicly funded financial incentives along with conventional schemes, such as R&D subsidies, to promote exports, particularly during a period of financial crisis.     

Agricultural productivity growth in Brazil: Large and small farms excel

The long-standing debate on the relationship between farm size and productivity has been generally limited by the range of farm sizes evaluated and the definition of productivity. In this paper we use data from three Brazilian agricultural censuses to address these issues. In particular, we introduce a wider distribution of farm sizes than presently available from the literature and we employ total factor productivity (TFP) as our performance measure. In doing so, we test which farm size class had the highest TFP levels in 1985 and 2006, how factor productivity growth varied within and across farm size classes between those years, and which policy or factor had the greatest productivity enhancing effect. When examining TFP growth, we move beyond the common decomposition into technical and efficiency changes by identifying the complete distribution of farm productivity performances. We find that by 2006 a U-shaped distribution of productivity over farm sizes had emerged. Considerable 1985–2006 TFP growth differences are prevalent; positive rates for the majority accompany stagnant or negative rates for some. Public education investments were associated with faster productivity growth regardless of farm size, while technical assistance’s positive effect and credit’s negative effect were associated with larger farm sizes. The role of specialization varied by size.     

基于能量消耗分析的乳状液液滴粒径计算关系式

在油水混输管道中,存在着大量粒径大小不一的乳状液液滴,液滴粒径及分布对油水混合液的粘度有重要影响,从而在很大程度上影响管道的压降。因此,研究乳状液液滴粒径的计算关系式对于描述油水两相的流动特性以及准确计算管道压降具有重要意义。针对4种原油,通过油水体系的乳化实验,研究了搅拌转速、温度及含水率对乳状液液滴粒径的影响。研究发现,搅拌转速增大,乳状液液滴粒径减小;温度升高,乳状液液滴粒径增大,并且在低温下增大的趋势较显著;含水率增加,乳状液液滴粒径有减小趋势,但减小的幅度不大;以火用损率来表征剪切过程中的能量消耗,建立了基于剪切火用损率分析的乳状液液滴粒径计算关系式。     

经济密度、人口规模与环境污染——基于城市面板数据的实证分析

选取2005-2016年285个地级及以上城市数据,利用静态和动态短面板模型分析经济密度和人口规模对环境污染的影响,分析表明:经济密度与环境污染之间存在“倒U型”关系,人口规模扩大会抑制污染物排放;不同等级城市经济密度、不同规模城市人口对环境污染的影响方向一致,但影响程度有所差异;前期污染排放对当期具有正向影响,环境污染物排放存在路径依赖;经济发展水平、工业产值占比和对外开放也是影响污染物排放的重要因素,但各指标对三类污染物排放的影响方向和影响程度存在差异。据此认为,在综合考虑城市具体空间区位条件下,人口适度集聚,提高城市经济密度,优化产业结构以及加强环境监管是环境治理的重要方向。     

On the role of Islamic and conventional banks in the monetary policy transmission in Malaysia: Do size and liquidity matter?

This paper empirically investigates the impact of monetary policy on the credit supply of Islamic versus conventional banks of Malaysia using an unbalanced panel dataset over the period 2005-2016. While estimating the effects of three alternative measures of monetary policy on banks' credit supply, we include several bank-specific and macroeconomic variables in the specification as control variables. We provide strong evidence on the existence of the credit channel of monetary policy transmission mechanism in Malaysia. Yet, we show that Islamic banks respond considerably less to changes in monetary policy instruments as compared to their conventional counterparts. We also find that the monetary policy measures affect small-sized banks and less-liquid banks more as compared to large-sized and more-liquid banks. Our findings suggest that for an effective monetary policy, there is a vital need to consider the nature of Islamic banking while devising any monetary policy instruments to manage credit supply in the economy.