基于SD模型的装配式建筑供应链脆弱性研究

装配式建筑供应链的运作存在很多不确定性。为提高供应链管理效率，促进建筑业的发展，运用供应链运作参考(SCOR)模型对装配式建筑供应链脆弱因子进行识别，将装配式供应链系统划分为6个子系统；通过系统动力学（SD）模型对供应链脆弱性进行仿真。结果表明，装配制造流程是脆弱性最大的子系统，整个供应链的脆弱性随着建筑项目的推进而增大。     

A Statistical Model to Investigate the Reproducibility Rate Based on Replication Experiments

The reproducibility crisis, that is, the fact that many scientific results are difficult to replicate, pointing to their unreliability or falsehood, is a hot topic in the recent scientific literature, and statistical methodologies, testing procedures and p‐values, in particular, are at the centre of the debate. Assessment of the extent of the problem–the reproducibility rate or the false discovery rate–and the role of contributing factors are still an open problem. Replication experiments, that is, systematic replications of existing results, may offer relevant information on these issues. We propose a statistical model to deal with such information, in particular to estimate the reproducibility rate and the effect of some study characteristics on its reliability. We analyse data from a recent replication experiment in psychology finding a reproducibility rate broadly coherent with other assessments from the same experiment. Our results also confirm the expected role of some contributing factor (unexpectedness of the result and room for bias) while they suggest that the similarity between original study and the replica is not so relevant, thus mitigating some criticism directed to replication experiments.     

Price discovery and volatility spillover in spot and futures markets: evidences from steel-related commodities in China

The price discovery and spillover effect are significant indicators in futures markets. This study examines the price discovery and spillover effects using vector error correction model and generalized autoregressive conditional heteroskedastic for seven types of steel products in Chinese spot and futures markets. The results show that the price discovery exists in all of steel futures market. It is also confirmed that futures prices in all items are mainly leading spot prices via permanent-transitory and information share. In the results of spillover effects, it is found that wire rod, coking coal, coke and silico-manganese have the effects between spot and futures market. In rebar market, there is the spillover effect from spot to futures. This information about futures prices can help the market participants to make decisions when they predict the spot prices.     

Settlement procedures and stock market efficiency

This study examines why most derivatives markets that settle on the day following expiration choose the opening rather than the closing price as the final settlement price (FSP), whereas most markets that settle on the expiration day select an average rather than a single price as the FSP. Four exogenous changes in the Taiwan Futures Exchange settlement procedures provide an experimental basis for studying the settlement procedures’ impact on underlying assets. Greatest market efficiency is observed when the FSP is determined by a single rather than an average price and hypothesize that manipulation is prevented at the expense of market quality.     

中美玉米期货市场功能效率比较

价格发现与套期保值是期货市场的基本功能,能够反映期货市场的运行效率。通过对比中美贸易摩擦前后期货市场的价格发现和套期保值功能,分析中美玉米期货市场效率间的差距,探究我国玉米期货市场运行效率低的原因。利用格兰杰(Granger)因果分析、协整检验、分位信息份额模型、套期保值比率及绩效分析方法,定量对中美两国2013—2019年玉米期货及现货的数据进行分析,结果表明,中国玉米期货市场存在较强的价格发现功能,但套期保值绩效不佳。使用前沿分位信息份额模型和滚动格兰杰因果法分析中美两国期现货市场动态关系的区别,发现中国仅存期货市场对现货市场的单向引导,而美国在中美贸易摩擦前表现为玉米期现货市场具有相近的引导能力,套期保值效率较高,中美贸易摩擦增强了其现货市场对期货市场的引导能力,降低了期货市场运行效率。从期现货市场双向引导关系视角来看,中国玉米期货市场效率低的原因主要是现货市场的信息不完全、发展不完善,期现货市场缺少长期稳定的双向引导关系抑制了期货市场功能发挥。中国应全面加强期货市场建设,提升期货市场定价效率,推动农产品期货市场快速健康发展。     

广西农业生态脆弱性评价及区划研究

［目的］随着经济的快速发展，我国各地区都面临着不同程度的农业生态脆弱性，通过研究特殊地形和气候下的农业生态脆弱性，有助于为农业生态环境的综合治理提供参考。［方法］文章以广西为例，通过构建评价指标体系，采用层次分析法和熵权法确定综合权重，通过构建综合评价模型对广西农业生态脆弱性程度进行评价，利用ArcGIS对生态脆弱性进行分级，以期探究广西农业生态脆弱性的空间分布情况。［结果］权重分析结果表明水蚀面积的权重值最高为0134，年平均降水量的权重值为0113，自然环境指标相对于农业生产和经济指标对农业生态脆弱性的影响更大。区划研究结果表明广西农业生态脆弱性区域大致可分为5个区域，分别是桂西峰丛洼地带、桂东山地丘陵地带、桂中低山丘陵地带、桂东北山地、桂南沿海丘陵地带。［结论］广西农业生态环境整体来看较为脆弱，处于轻度和中度脆弱等级，但生态环境问题仍不容忽视。为了改善农业生态脆弱性，政府应实行区域的联合防治，加大对农业生态环境的监督和治理，积极探寻生态、环保的农业发展方式，调整产业结构，改善农业生态环境的状态，促进广西农业的可持续发展。     

Landslide risk perception survey in Angra dos Reis (Rio de Janeiro,southeastern Brazil): A contribution to support planning of non structural measures

The increasing magnitude and frequency of landslide-related disasters exposes weaknesses in disaster risk reduction (DRR) policy. One of the underlying reasons is that DRR policies tend to focus only on the physical aspects of the problem (i.e. mass movement processes) while neglecting the level of vulnerability of exposed populations to landslide threats, which affects the types and magnitude of adverse consequences. This neglect is a typical symptom of the remoteness that can exist between public administrators and local communities and undermines the implementation of participatory risk management. Certain dimensions of vulnerability depend on how communities relate to the issue of disasters based on their intuitive or rational judgment, i.e. their perception of risk. This paper seeks to shed light on the need for an understanding of risk perception based on the findings from a survey of residents in the city of Angra dos Reis, Rio de Janeiro, Brazil, to be taken into account in aiming at a more efficient landslide risk management policy. The survey was carried out through semi-structured face-to-face interviews with residents of three typical hillside communities in this municipality. In general, the study found that residents will often weigh landslide risks against other threats and opportunities existing where they live. It also found that community members find it difficult to see themselves as agents of change in the environment where they live and in mitigating landslide risks, and that better communication is needed between the government agencies involved in risk management and local residents.     

The price discovery role of day traders in futures market: Evidence from different types of day traders

Using proprietary account-level transaction data in the futures market where day traders are self-declared ex ante, this study investigates whether day traders enhance price discovery at the market level. From a natural classification of day traders, we find that heterogeneous day traders have differential effects on price discovery. Self-declared day traders, who benefit from low margin requirement, do not improve price discovery measured by information share. In contrast, non-declared traders, who are not self-declared as day traders, improve price discovery. Their positive impacts on price discovery are particularly significant during periods of high volatility and arrival of new information. Overall, a margin stimulating policy may encourage more day trading, but may also attract overconfident investors, especially inexperienced ones, and who do not enhance price discovery.