岩石峰值应力前后声发射特性研究

采用TAW-2000D微机控制电液伺服岩石三轴试验机和SDAES型数字声发射仪组成的动态测试系统,对云南大红山铜矿白云岩进行了单轴压缩条件下的声发射试验,研究岩石在峰值应力前后声发射特性。试验结果表明:加载早期就有声发射活动,岩样在试验接近峰值强度时单位时间内的应力增长速度减小、声发射事件率出现明显下降,即出现相对平静期,峰值强度后的声发射现象仍然明显。     

Nowcasting South African gross domestic product using a suite of statistical models

Given lags in the release of data, a central bank must ‘nowcast’ current gross domestic product (GDP) using available quarterly or higher frequency data to understand the current state of economic activity. This paper uses various statistical modelling techniques to draw on a large number of series to nowcast South African GDP. We also show that GDP volatility has increased markedly over the last 5 years, making GDP forecasting more difficult. We show that all the models developed, as well as the Reserve Bank's official forecasts, have tended to overestimate GDP growth over this period. However, several of the statistical nowcasting models we present in this paper provide competitive nowcasts relative to the official Reserve Bank and market analysts' nowcasts.     

High-frequency credit spread information and macroeconomic forecast revision

We examine whether professional forecasters incorporate high-frequency information about credit conditions when revising their economic forecasts. Using a mixed data sampling regression approach, we find that daily credit spreads have significant predictive ability for monthly forecast revisions of output growth, at both the aggregate and individual forecast levels. The relationships are shown to be notably strong during ‘bad’ economic conditions, which suggests that forecasters anticipate more pronounced effects of credit tightening during economic downturns, indicating an amplification effect of financial developments on macroeconomic aggregates. The forecasts do not incorporate all financial information received in equal measures, implying the presence of information rigidities in the incorporation of credit spread information.     

Oil price shocks and economic growth: The volatility link

This paper shows that oil shocks impact economic growth primarily through the conditional variance of growth. Our comparison of models focuses on density forecasts. Over a range of dynamic models, oil shock measures and data, we find a robust link between oil shocks and the volatility of economic growth. We then develop a new measure of oil shocks and show that it is superior to existing measures; it indicates that the conditional variance of growth increases in response to an indicator of the local maximum oil price exceedance. The empirical results uncover a large pronounced asymmetric response of the growth volatility to oil price changes. The uncertainty about future growth is considerably lower than with a benchmark AR(1) model when no oil shocks are present.     

Asymmetry,Complementarities, and State Dependence in Federal Reserve Forecasts

Forecasts are a central component of policymaking; the Federal Reserve's forecasts are published in a document called the Greenbook. Previous studies of the Greenbook's inflation forecasts have found them to be rationalizable but asymmetric if considering particular subperiods, for example, before and after the Volcker appointment. In these papers, forecasts are analyzed in isolation, assuming policymakers value them independently. We analyze the Greenbook forecasts in a framework in which the forecast errors for different variables are allowed to interact. We find that allowing the losses to interact makes the unemployment forecasts virtually symmetric, the output forecasts symmetric prior to the Volcker appointment, and the inflation forecasts symmetric after the onset of the Great Moderation.     

Fiscal rules and budget forecast errors of Italian municipalities

We study the impact of the domestic stability pact on the accuracy of budget forecasts of Italian municipalities. Identification of the causal effect exploits a quasi-natural experiment generated by the removal in 2001 of the fiscal restraints on budget decisions for municipalities with fewer than 5000 inhabitants and by stricter budgetary restrictions and severe penalties for noncompliers in 2002. We find that relaxing fiscal rules had a sizeable impact on budget forecast errors, especially in 2002. In fact, revenue (expenditure) forecast errors for municipalities with fewer than 5000 inhabitants became 26% (22%) larger than in the past.     

Forecasting China's GDP growth using dynamic factors and mixed-frequency data

Forecasting GDP growth is important and necessary for Chinese government to set GDP growth target. To fully and efficiently utilize macroeconomic and financial information, this paper attempts to forecast China's GDP growth using dynamic predictors and mixed-frequency data. The dynamic factor model is first applied to select dynamic predictors among large amount of monthly macroeconomic and daily financial data and then the mixed data sampling regression is applied to forecast quarterly GDP growth based on the selected monthly and daily predictors. Empirical results show that forecasts using dynamic predictors and mixed-frequency data have better accuracy comparing to traditional forecasting methods. Moreover, forecasts with leads and forecast combination can further improve forecast performance.     

大城市劳动力供需平衡与外来劳动力就业政策研究——以上海市为例

文章在经济转型和大城市人口调控背景下,研究了上海劳动力资源供需平衡趋势与外来劳动力需求情况。研究显示,在上海经济保持一定的增长速度下,2015-2020年外来劳动力需求量在700-856万人之间,这使大城市在对待外来劳动力上处于尴尬境地,一方面面临着经济发展对外来劳动力的依赖性,另一方面面临着大城市人口调控的压力。目前上海劳动力市场中外来劳动力与本地劳动力在就业岗位、工资待遇、社会福利等方面仍存在一定的差异。外来劳动力与本地劳动力在岗位上更多的是一种优势互补关系,对外来劳动力歧视有悖于社会公平理论,同时政府的强行调控政策也不利于劳动力市场的发展。政府的职责应该是尽可能地创造出健康、有序、公平的市场秩序,让市场在调节劳动力供需和结构性短缺上发挥决定性作用。     

Technology fusion: Identification and analysis of the drivers of technology convergence using patent data

The concepts of technology convergence or technology fusion describe the phenomenon of technology overlap. Despite evidence of the higher value associated to interdisciplinary research and cross-industry innovation, few studies have investigated the characteristics of technology fusion based on patent data. This study identifies new cases of convergence relying on the International Patent Classification (IPC) of patents filed at the European Patent Office between 1991 and 2007: the first occurrence of a patent incorporating a combination of IPC subclasses signals a new instance of fusion. Duration models are employed to investigate the impact of field level characteristics derived from patent bibliometrics on the likelihood of identifying a new fusion. The results show that merges are more frequent if the focal technology fields are closely related (based on a higher number of cross citations), are characterized by wide technological scope, and are the result of an inter-firm collaboration. In contrast to previous findings, the results show that the more complex the technologies involved, the less the likelihood of their convergence or fusion. The correlation between fusion likelihood and the characteristics of the merging fields could help managers and policymakers to predict the emergence of new technology areas.     

The Application of Temperature-Measuring to the Forecast of Gush Water Inside the Shilin Tunnel

提出了用温度梯度量测预报隧道突水。阐述了利用掌子面温度变化预报隧道突泥突水的基本原理；结合石林隧道的工程实践，介绍了该方法的实施步骤和效果。为超前地质预报提供了一个新的途径。