The struggle for space: Past and future of the space race

This article is geared toward shedding some more light on what may be the next space race and its contours.Space flight is undoubtedly a human achievement of the second half of the 20th century, and probably the most audacious one of the past century. The space race started suddenly in the 1950s and has grown explosively during the following two decades, but decreased steadily after the 1970s. After the 1990s, however, we have seen a shy rebirth of space-related activities, when many other actors (states) entered the stage, adding up to the agonizing role of the two-actor piece that we have witnessed during the so-called Cold War.The opening years of the 21st century provided a more complex narrative for space exploration. At the start of the new millennium a new technosphere [1] emerged, dominated by what is used to be called as the Information and Communications Technologies (ICT), with the Internet playing the leading role among the bandwagon of technological novelties that appeared during the twilight of space activities. In despite of the fact that artificial satellites represent the very backbone of the global communications system, space activities seem to play a secondary role amidst the apparently accelerated rate of change concerning the technological systems of the present technosphere. But, as it is demonstrated in this paper, things are changing, and very probably a renewed space race will unfold in the coming decades.A question may be placed: what happened? Why the Earth stood still with regard to the race toward the cosmos? Answer: futurists, even prestigious ones like Herman Kahn and Arthur Clarke, did not consider the existence of socioeconomic long waves (Kondratieff waves, or K-waves for short) with their two decades long economic downturn, which has contributed to the deceleration of space-related activities.Analyzing the worldwide evolving scenario of space-related activities during the last eighty years under the framework of the succeeding K-waves and applying some technological forecasting tools, namely the logistic analysis, technological surveillance and intensive data mining, scrutinizing more than 7500 events occurred in the period 1930–2010 related with space activities, it is demonstrated that the space race like the one that we have witnessed until now is a natural growth process that has saturated at the dawn of this century. The same analysis demonstrates that a new growth process in this field might be nowadays under way with contours very different from that imagined by futurists and science fiction writers sixty years ago. Also the main trends in the usage of launching vehicles and satellites are framed and discussed in this paper.     

Computing DSGE models with recursive preferences and stochastic volatility

This paper compares different solution methods for computing the equilibrium of dynamic stochastic general equilibrium (DSGE) models with recursive preferences such as those in Epstein and Zin, 1989, Epstein and Zin, 1991 and stochastic volatility. Models with these two features have recently become popular, but we know little about the best ways to implement them numerically. To fill this gap, we solve the stochastic neoclassical growth model with recursive preferences and stochastic volatility using four different approaches: second- and third-order perturbation, Chebyshev polynomials, and value function iteration. We document the performance of the methods in terms of computing time, implementation complexity, and accuracy. Our main finding is that perturbations are competitive in terms of accuracy with Chebyshev polynomials and value function iteration while being several orders of magnitude faster to run. Therefore, we conclude that perturbation methods are an attractive approach for computing this class of problems.     

多层级视角下京津冀科技创新政策府际关系研究

府际关系协调有利于实现创新资源、要素的有效汇聚与整合,进而提升政策有效性。以京津冀为例,构建中央-地方多层级府际关系模型,分析中央政策主体合作网络特征与政策扩散特征、地方政策主体合作网络特征与政策执行特征的相关性。研究发现,中央政府部门间形成了以科技部为核心的核心—边缘网络结构特征;北京市政府部门间呈现出以中关村科技管理委员会为核心的核心-边缘网络结构特征;天津市政府部门间呈现出以天津市科学技术委员会为核心的星型网络结构特征;河北省则没有形成稳定的网络关系。中央政策主体合作网络中的度中心性与政策扩散广度具有相关性;地方政策主体合作网络中介中心性、度中心性与政策执行强度具有相关性。     

Impact of state-dependent oil price on US stock returns using local projections

In this paper, we investigate the impact of oil prices on both aggregate and industry US real stock returns over the period 1973–2017. The empirical analysis contributes to the related literature introducing a state-dependent oil price (high and low) and the local projections approach. Our main finding is that, depending on the nature of the shock and industry, the negative effects of oil price shocks become exacerbated -and the positive effects get moderated- if oil prices are already high.     

The Canadian productivity stagnation, 2002–2014

Total factor productivity (TFP) growth in Canada between 2002 and 2014 has been only 0.16% per year. This figure is substantially smaller than that of the United States, or that of Canada in the past. We perform multiple counterfactual exercises to show that this small TFP growth cannot be accounted for by several compositional effects or mismeasurements of factors of production. We identify two key sectors (mostly Mining and to a lesser extent Manufacturing) that drive all of the TFP growth difference with the United States. Despite the lack of TFP growth, Canada has experienced sustained income growth due to a prolonged period of appreciation of the terms of trade (while US terms of trade have deteriorated), making real income in the two countries grow at similar rates.     

科技创新人才区域性需求趋势研究

科技创新人才是结构转型和经济社会高质量发展的重要支撑力量。运用灰色系统GM（1,1）模型,对四川、陕西、上海三省市2017-2021年科技创新人才进行需求预测和比较分析。R语言求解结果表明,三地及高技术产业对科技创新人才的需求数量均呈稳步增长态势,但增速存在区域性差异,新的科技创新人才发展区域性非均衡态势将逐渐形成,区域性人才竞争将进一步加剧。加大科技创新人才培育力度,合理规范人才竞争应成为国家层面的人才政策;加快产业转型升级、优化人才生态环境、提高人才与产业匹配度既是优化人才资源配置效率的关键,也是区域性人才管理工作的重点。     

Quantitative properties of sovereign default models: Solution methods matter

We study the sovereign default model that has been used to account for the cyclical behavior of interest rates in emerging market economies. This model is often solved using the discrete state space technique with evenly spaced grid points. We show that this method necessitates a large number of grid points to avoid generating spurious interest rate movements. This makes the discrete state technique significantly more inefficient than using Chebyshev polynomials or cubic spline interpolation to approximate the value functions. We show that the inefficiency of the discrete state space technique is more severe for parameterizations that feature a high sensitivity of the bond price to the borrowing level for the borrowing levels that are observed more frequently in the simulations. In addition, we find that the efficiency of the discrete state space technique can be greatly improved by (i) finding the equilibrium as the limit of the equilibrium of the finite-horizon version of the model, instead of iterating separately on the value and bond price functions and (ii) concentrating grid points in asset levels at which the bond price is more sensitive to the borrowing level and in levels that are observed more often in the model simulations. Our analysis is also relevant for the study of other credit markets.     

Determinants of bank’s interest margin in the aftermath of the crisis: the effect of interest rates and the yield curve slope

Empirical Economics - This paper analyses the determinants of net interest margin, focusing on the impact of interest rates and the slope of the yield curve, using a broad panel of data from 32...     

关于备件物流研究现状的综述

论述了备件物流研究的基本过程,并对国了内外备件物流的研究状况进行了综述,最后对未来备件物流研究做了展望。     

Diversity, persistence and chaos in consumption patterns

In this paper we present a model from which discretionary consumption dynamics can be analyzed as global properties emerging from the endogenous transformation of a society inhabited by boundedly rational interactive consumers. By considering local and global interactions among consumers, we show that behavioral diversity plays a central role in the evolution of consumption patterns. The analysis of the model reveals the existence of a regime characterized by the persistence of different social standards, and a time evolution of the social distribution of behavioral patterns towards a heteroclinic cycle. In some cases the evolution seems to be chaotic, generating unpredictable, erratic dynamics of the aggregate social indices (average or social propensity for discretionary consumption).