A Dynamic Leontief Model with Non-renewable Resources

In this paper we study a generalization of the dynamic Leontief input–output model. We extend the standard dynamic Leontief model with the balance equation of non-renewable resources. Obviously, the non-renewable stocks will decrease, exploiting primary resources. In this study we examine the controllability of this extended model by taking the consumption as the control parameter. Assuming balanced growth for both consumption and production, we investigate how long these scarce resources will cover the input needs of production and how the lifetime of the system depends on the balanced growth rate and on the consumption. In doing so, we apply classic results from control theory and on eigenvalue problems in linear algebra.     

企业集群的动力机制:权利不平等的流动性本质

文章论述了现实中经常被学者们忽视的权利不平等,而其流动性本质正是企业集群产生、成长和消亡的动力机制.本文首先对企业集群中的权利和权利环的概念给以解释,并指出权利不平等是特定时间和空间下的产物,它具有流动性的本质;然后我们用权利和权利环的概念解释了企业集群成长的条件--开放性和过度融合问题,结果发现权利不平等的一种流动性本质正是有利于企业集群的成长动力源;最后指出该结论的实践意义.     

Trend forecasting for stability in supply chains

This paper revisits the use of trend forecasting to determine ordering policy in supply chains by viewing it as a part of the control process for making the supply responsive to demand. Trend forecasting is often used to assess demand — a tracked variable in the control context, which drives supply — a tracking variable. Used in this way, it is often observed to increase instability creating the so-called bullwhip effect. Trend is used on the other hand with reliability to increase stability in controller control, but with the difference that a trend of a tracking variable is used to drive correction. While both processes involve use of trend to determine policies for achieving reliable performance, the outcomes of the former are variable while those of the later can create improvement in control with certainty. The similarities and differences between the two processes are discussed and guidelines developed for applying trend forecasting to enhance stability in supply chains.     

云南省水富县小城镇发展的动因和对策研究

对云南省昭通市水富县的城镇化的现状进行调查分析,从内因和外因两个方面研究了水富县小城镇发展的动力机制,提出水富县加快小城镇发展的战略选择和措施。     

Estimating the relative efficiency of various forms of prevention at different stages of a drug epidemic

Drug use and problems change dramatically over time in ways that are often described as reflecting an “epidemic cycle”. We use simulation of a model of drug epidemics to investigate how the relative effectiveness of different types of prevention varies over the course of such an epidemic. Specifically we use the so-called LHY model (see, Discussion Paper No. 251 of the Institute of Econometrics, OR, and Systems Theory, Vienna University of Technology, Vienna, Austria, 2000) which includes both “contagious” spread of initiation (a positive feedback) and memory of past use (a negative feedback), which dampens initiation and, hence, future use. The analysis confirms the common sense intuition that prevention is more highly leveraged early in an epidemic, although the extent to which this is true in this model is striking, particularly for campaigns designed to preserve or amplify awareness of the drug's dangers. The findings also suggest that the design of “secondary” prevention programs should change over the course of an epidemic.     

现阶段地方政府保障房建设的动力机制研究

现阶段政府保障房建设的任务艰巨,能否保质保量地完成任务关键在于解决地方政府保障房建设的动力机制问题。因此,文章梳理了近年来经济适用房、廉租房、公租房等保障房建设量,保障房建设土地供给量以及保障房建设资金投入量等数据,对地方政府保障房建设数量不足、土地供应计划执行不力、资金投入量不到位、部分保障房质量不达标等动力不足的表现进行考察;进而从公共选择理论的视角,以"经济人"假设为逻辑起点,剖析地方政府行为逻辑及保障房建设动力不足的原因;最后提出完善财税体制、监督问责机制、政绩考核机制以及引入民间资本参建保障房等激发地方政府保障房建设内在动力和加强外在推力与引力的对策,以促进住房保障事业的可持续发展。     

Forecasting stock market returns over multiple time horizons

In this paper, we seek to demonstrate the predictability of stock market returns and explain the nature of this return predictability. To this end, we introduce investors with different investment horizons into the news-driven, analytic, agent-based market model developed in Gusev et al. [Algo. Finance, 2015, 4, 5–51]. This heterogeneous framework enables us to capture dynamics at multiple timescales, expanding the model’s applications and improving precision. We study the heterogeneous model theoretically and empirically to highlight essential mechanisms underlying certain market behaviours, such as transitions between bull and bear markets and the self-similar behaviour of price changes. Most importantly, we apply this model to show that the stock market is nearly efficient on intraday timescales, adjusting quickly to incoming news, but becomes inefficient on longer timescales, where news may have a long-lasting nonlinear impact on dynamics, attributable to a feedback mechanism acting over these horizons. Then, using the model, we design algorithmic strategies that utilize news flow, quantified and measured, as the only input to trade on market return forecasts over multiple horizons, from days to months. The backtested results suggest that the return is predictable to the extent that successful trading strategies can be constructed to harness this predictability.     

The minimal model of financial complexity

A representative investor generates realistic and complex security price paths by following this trading strategy: if, a few ticks ago, the market asset had two consecutive upticks or two consecutive downticks, then sell, and otherwise buy. This simple, unique, and robust model is the smallest possible deterministic model of financial complexity, and its generalization leads to complex variety. Compared to a random walk, the minimal model generates time series with fatter tails and more frequent crashes, thus more closely matching the real world. It does all this without any parameter fitting.     

银行资产配置趋势与中央银行流动性管理——基于动力系统模型的模拟分析

近年来,我国宏观流动性投放逐步由以前的被动投放(外汇占款)向主动投放转变,银行业资产配置结构更趋多元化,金融创新更加活跃,这些都在一定程度上改变了金融体系流动性传导的渠道和机制,迫使我们重新审视流动性在金融体系中消长、转移的内在逻辑,探讨新形势下流动性管理的合理方式和路径。本文运用动力系统模型来分析和论证银行资产配置结构变化对市场流动性状况的影响机制,以及中央银行流动性管理工具的有效性。研究表明,银行资产配置趋势的同质化容易导致市场流动性状况的恶化;中央银行需要进一步完善利率传导机制,强化货币政策与宏观审慎评估政策的协同配合,以提升流动性管理的有效性。     

Development of a technological competition model in the presence of network effects from the modified law of Metcalfe

The objective of this paper is to propose a new model of competence in presence of network effects. We will introduce some modifications in the Lotka-Volterra model, in order to solve its deficiencies. The main improvement is to introduce a modification of Metcalfe’s Law, what allow us to reflect the effect of congestion externalities. The model’s validation, developed by numerical simulation, confirms that its behaviour is quite similar to that observed in real markets.