A supportive architecture for CFD-based design optimisation

Multi-disciplinary design optimisation (MDO) is one of critical methodologies to the implementation of enterprise systems (ES). MDO requiring the analysis of fluid dynamics raises a special challenge due to its extremely intensive computation. The rapid development of computational fluid dynamic (CFD) technique has caused a rise of its applications in various fields. Especially for the exterior designs of vehicles, CFD has become one of the three main design tools comparable to analytical approaches and wind tunnel experiments. CFD-based design optimisation is an effective way to achieve the desired performance under the given constraints. However, due to the complexity of CFD, integrating with CFD analysis in an intelligent optimisation algorithm is not straightforward. It is a challenge to solve a CFD-based design problem, which is usually with high dimensions, and multiple objectives and constraints. It is desirable to have an integrated architecture for CFD-based design optimisation. However, our review on existing works has found that very few researchers have studied on the assistive tools to facilitate CFD-based design optimisation. In the paper, a multi-layer architecture and a general procedure are proposed to integrate different CFD toolsets with intelligent optimisation algorithms, parallel computing technique and other techniques for efficient computation. In the proposed architecture, the integration is performed either at the code level or data level to fully utilise the capabilities of different assistive tools. Two intelligent algorithms are developed and embedded with parallel computing. These algorithms, together with the supportive architecture, lay a solid foundation for various applications of CFD-based design optimisation. To illustrate the effectiveness of the proposed architecture and algorithms, the case studies on aerodynamic shape design of a hypersonic cruising vehicle are provided, and the result has shown that the proposed architecture and developed algorithms have performed successfully and efficiently in dealing with the design optimisation with over 200 design variables.     

Has the ‘franc fort’ exchange rate policy affected the inflationary dynamics? Theory and new evidence

Abstract

This paper examines the impact of the ‘franc fort’ policy implemented in France from 1983 on the inflationary dynamics by means of a square root Kalman filter approach. An interesting aspect of the analysis is the evidence that the ‘franc fort’ exchange rate policy had a significant impact on the inflationary dynamics in France through its credibility effects. These results confirm the imported credibility hypothesis according to which the French authorities accelerated the disinflation process by importing the German monetary policy credibility through the ‘hard peg’ of the franc–DM exchange rate. These findings show that inflation dynamics in France began to converge significantly to that in Germany after the implementation of the ‘franc fort’ policy, making more credible the plan for the final transition to the euro. Moreover, this analysis may also reveal much about the nature of potential success of the current initiative of the new member countries now in the process of joining the EU and looking eventually to adopt the euro.     

Contractibility,Strategy, and Network Dynamics: From Franchising to Licensing

The article examines the network dynamics from franchising to licensing due to the increase of contractibility of the franchiser's system-specific assets as determinant of the allocation of decision rights between the network partners. Based on the property rights approach, residual decision rights must be allocated according to the distribution of intangible knowledge assets between the franchiser and franchisee. Our analysis derives the following hypothesis: The more contractible the franchiser's system-specific assets, the higher is the tendency from franchising toward licensing. In addition, we investigate the impact of strategy change on the standardization (contractibility) of system-specific assets and the network governance. We argue that a change of strategy may increase the contractibility of system-specific know-how and consequently the tendency toward licensing. This study presents empirical evidence from company Getifix on the network dynamics from franchising to licensing.     

Roy Harrod and traditional theory

In 1926 and 1936 Sraff and Keynes attacked the methodological core of traditional economic theory by showing that the premises of partial equilibrium analysis were mutually inconsistent.

this paper aims to show that Harrod neglected Sraffa and Keynes's logical arguments, and only admitted that the tacit assumptions under discussion restricted the domain of validityof the theory to special cases: perfect competition and statics. He then proceeded to generalize the theory to imperfect competition and dynamics by applying the principles (but not the instruments) of traditional analysis. The definition of these domains thus aimede at rescuing as mush as possible from the orthodox approach.     

Income inequality and economic growth

Despite the extensive existing literature on income inequality and economic growth, there remains considerable disagreement on the effect of inequality on economic growth. Existing literatures find either a positive or a negative relationship. In this paper, we attempt to theoretically examine that relationship with a stochastic optimal growth model. We make the disagreement clear within a single model. We conclude (i) that both are possible – that is, higher inequality can retard growth in the early stage of economic development, and can encourage growth in a near steady state, (ii) that income redistribution by high income tax does not always reduce income inequality. Income inequality can be reduced by higher income tax in a near steady state, but it cannot be reduced in the early stage of economic development, and (iii) that two government polices – rapid economic growth and low income inequality – can be achieved by low income tax in the early stage of economic development, but both cannot be achieved simultaneously in a near steady state.     

高科技产业新产品定价策略研究——基于系统动力学

新产品的开发对于高科技产业来说日趋重要，需要不断的努力和巨大的市场意识，系统的价格监测对于分割市场和合理配置资源具有很重要的意义，企业应该认真考虑以确定最优定价策略。本文在不同竞争环境下建立了不同定价策略对企业综合影响的系统动力学模型，在对模型模拟分析的基础上，研究了不同定价策略对企业的影响。结果表明，高科技产业新产品采用撇脂定价策略相对于渗透定价策略具有更大的优越性，并根据企业实际的定价能力，适当地延长撇脂时间和增大撇脂价格可以带来更大的经济效益。     

Downward wage rigidity and business cycle asymmetries

The growth rates of wages, unemployment and output of a number of OECD countries have a strongly skewed distribution. In this paper we analyze to what extent downward wage rigidities can explain these empirical business cycle asymmetries. To this aim, we introduce asymmetric wage adjustment costs in a New-Keynesian DSGE model with search and matching frictions in the labor market. Increasing wages is less costly than cutting them. It follows that wages increase relatively fast and thus limit vacancy posting and employment creation, but they decline more slowly, leading to a strong reduction in vacancies and employment. The presence of downward wage rigidities strongly improves the fit of the model to the observed skewness of labor market variables and the relative length of expansions and contractions in the output and the employment cycles. The asymmetry also explains the differing transmission of positive and negative monetary policy shocks from wages to inflation.     

UNDERSTANDING THE FINANCIAL CONSEQUENCES OF THE BULLWHIP EFFECT IN A MULTI‐ECHELON SUPPLY CHAIN

This article is concerned with how supply chain strategies can mitigate the Bullwhip Effect and inflated inventories from the perspective of the central firm (typically a manufacturer) in the supply chain. We first outline a base case scenario with a validated system dynamics simulation model, using supply chain characteristics as reported by a real firm, in this case a Mexican electronics supplier to U.S. automobile assemblers. We find, surprisingly, that a lower Bullwhip Effect Index (BE) does not always lead to lower costs in the supply chain studied. Furthermore, sensitivity analysis suggests some interesting, counterintuitive results. The implications of these findings are further developed as we test how lead time reduction can also reduce the Bullwhip Effect in the simulated setting.     

How to deal with real estate booms: Lessons from country experiences

The financial crisis showed, once again, that neglecting real estate booms can have disastrous consequences. In this paper, we spell out the circumstances under which a more active policy agenda on this front would be justified. Then, we offer insights on the pros and cons as well as implementation challenges of various policy tools that can be used to contain the damage to the financial system and the economy from real estate boom–bust episodes. These insights derive from econometric analysis, when possible, and case studies of country experiences. Broadly, booms financed through credit and involving leverage are more likely to warrant a policy response. In that context, macroprudential measures can be targeted more precisely to specific sources of risk, but they may prove ineffective because of circumvention. In that case, monetary policy may have to be used to lean against the wind.     

The Dynamics of Self-Esteem and Physical Self: Between Preservation and Adaptation

The aim of this study was to model and characterize the psychologicalprocesses that underlie the dynamics of global self-esteem and physicalself over time. Twice a day for 228 consecutive days, seven participantscompleted a short inventory (PSI-6, Ninot et al., 2001) measuring sixsubjective dimensions: global self-esteem, physical self-worth, physicalcondition, sport competence, physical strength, and attractive body.Each series was modeled by means of ARIMA procedures. The resultsshowed that a simple moving average model provided a satisfactoryaccount for the dynamics of all series. This model suggests that acombination of two opposite processes underlies the dynamics ofself-concept: preservation, which tends to restore the previousvalue after a disturbance, and adaptation, which tends to inflectthe series in the direction of the perturbation.