Optimal fiscal policy with robust control

This paper analyzes how consumer uncertainty affects optimal fiscal policy in the Lucas and Stokey (1983) framework. The consumers, lacking confidence in their knowledge of the stochastic environment, endogenously tilt their subjective probability model away from an approximating probability model. The government, though, is confident that the approximating probability model characterizes the stochastic environment. This confidence dichotomy reveals a range of possible objective functions for an altruistic government. I assume that the government maximizes the consumers' expected utility under the consumers' own subjective probability model. It is found that this government relies less heavily on labor taxes to absorb the fiscal shock than would be optimal if consumers were fully confident in their probability model. This policy helps mitigate the direct welfare cost associated with consumer uncertainty. I compare this policy to the one implemented by a government that maximizes the consumers' expected utility under the approximating probability model.     

Dynamic control of rural–urban migration

This study investigates the optimal urbanization control of an underdeveloped economy by specifying a simple dynamic rural–urban model in which the urban sector bears both an intertemporal positive externality and a simultaneous negative externality. The dynamic optimization problem is solved for the political intervention of the central government in an intersectoral population distribution with taxes and subsidies. Our analysis provides the following results: (i) a big-push policy that leads an economy to a higher-income steady state with urbanization is not necessarily desirable if the government cannot borrow money at a sufficiently low interest rate; (ii) in order to sustain an appropriate urbanization speed, urbanization control policy should have a switch: the urban sector should be subsidized in order to accelerate rural–urban migration in early stages of development, and taxed to decelerate and eventually cease the migration in later stages.     

DEA efficiency in agriculture: Measurement unit issues

The selection of inputs and outputs in DEA models represents a vibrant methodological topic. At the same time; however, the problem of the impact of different measurement units of selected inputs is understated in empirical literature. Using the example of Czech farms, we show that the DEA method does not provide consistent score estimates, neither a stable ranking for different popular measurements of labour and capital factors of production. For this reason, studies based on DEA efficiency results for differently measured inputs should be compared only with great caution.     

Optimal pollution control with distributed delays

We present a model of optimal stock pollution control with general distributed delays in the stock accumulation dynamics. Using generic functional forms and a distribution structure covering a wide range of distributions, we solve analytically the complex dynamic system that arises from the introduction of these distributed delays. From a theoretical standpoint, our contribution extends the dynamic optimization literature that focused on single discrete delays and develops an original method to address control problems written as mixed type functional differential equations with general kernels. Our results show the qualitative impact of acknowledging these distributed delays on the optimal pollution paths dynamics. We study analytically the properties of the dynamics and we identify the conditions for the occurrence of limit cycles. This theoretical work contributes to the design of efficient environmental policies in the presence of complex delays.     

Optimal control of pricing strategy for diffusion model

This study presents a conceptual framework based on the new product diffusion and demand theory models. The proposed framework was creating a probability of demand function. Considering effectiveness of demand function transmitted by adopters, the optimal control policies of pricing are conducted according to the optimal control theorv.     

Economic dynamics of reservoir sedimentation management: Optimal control with singularly perturbed equations of motion

We analyze the economic dynamics of reservoir sedimentation management using the hydrosuction-dredging sediment-removal system. System dynamics depend on two interdependent hydraulic processes evolving at different rates. The accumulation of water impounded in the reservoir evolves on a ‘fast’ time scale, while the loss of water storage capacity to trapped sediments evolves on a ‘slow’ time scale. We formulate a multidimensional optimal control problem with singularly perturbed equations of motion to accommodate the disparate time scales. We apply singular perturbation methods to approximate (via polynomial series expansion) a ‘slow’ manifold reducing multi-dimensional solution space to the single-dimensional subspace confining long-term dynamics.     

The business cycle in the G-7 economies

In this paper the Hodrick–Prescott filter is used to decompose real GDP for the G7 countries into cyclical and trend components. The resulting series of cyclical components are then examined for static relationships, using correlations and graphs; long-run relationships using autoregressive-distributed lag models; and short-run relationships, using error–correction models. The main result is that the patterns of cyclical behaviour changed following the oil price shocks in the 1970s. Since 1980, cyclical fluctuations have been smaller as a result of a decline in synchronisation of the cycles in the G7. Two separate cycles seem to be developing since 1990. One is for Germany, Italy and France, whilst the other is for the US, UK and Canada. Within each of these groups there are both long-run and short-run relationships between the cyclical components of GDP.     

Optimal money supply in models with endogenous discount factor

This paper studies the Friedman rule for the optimal quantity of money in money in the utility (MIU) and cash–credit models while considering two specifications for the endogenous discount factor. In the first specification, the discount factor depends directly on the utility level. In the second, the discount factor depends on every component of the utility function. We show that under the former specification the Friedman rule is the optimal policy. Under the latter, however, while the Friedman rule is optimal for the MIU model, it is not optimal for the cash–credit model.     

On the interpretation of cointegration in the linear–quadratic inventory model

The traditional formulation of the linear–quadratic inventory model with unit roots predicts cointegration between inventories and sales. That formulation implies that marginal production costs and the marginal benefits of inventories are both tending to ∞, and the cointegrating coefficient reflects the optimal trade-off between these competing factors. This paper suggests a reformulation of the problem in which marginal production costs and marginal inventory benefits are both stationary and in which the cointegrating coefficient is the same as the value that characterizes the target inventory level in the cost function.     

内部控制体系在AB企业运营中的实际应用

本文以内部控制体系概念为基本出发点来讲内部控制在合资企业中的实践及运用：首先以临全球化竞争的中国企业需要提高企业的经营管理水平，而内部控制体系建设是企业经营管理水平提高重中之重引出内部控制体系建设的必要性；其次阐述了内部控制的定义、框架、作用和其自身的局限性最後以AB企业合资工厂的实践浅论内部控制体系在企业运营中的实际运用。     

试论可编程程序控制器(PLC)在电器控制中的应用

可编程程序控制器(PLC)如今已广泛运用于电器控制中。可编程程序控制器除了可以按事先编好的程序进行不同的逻辑控制,还具有自动诊断、随意编程、体积小、通用性好、可靠性高等特点。所以,可编程程序控制器正在逐步取代继电器-接触器控制系统。     

烧结配料工序中的精矿总量控制

文章以某钢铁公司的烧结厂为例,针对烧结配料工序中存在的问题,提出了精矿总量控制的理念和具体的解决方案,并对实际运行情况进行了分析和说明。     

Business conditions, shared resources and integrative practices in the supply chain

Integration is one of the important concepts in supply chain management. Both in theoretical and empirical contributions, it is shown that integrative practices improve supply chain performance. Our knowledge with respect to which integrative practices are appropriate under different circumstances is limited. This paper develops propositions regarding the influence of business conditions and the type of resources on integrative practices in links between buyers and suppliers. We will study nine business units and the relationship with their key buyers. For each unit, we will investigate the business conditions, the employment of resources for key buyers and the type and level of integrative practices. Higher complexity in business conditions requires higher levels of integration (specifically in the areas of planning and organisation), which are stimulated by buyer-focused resources and restricted by shared resources. In case of lower complexity, we find lower levels of integrative practices. Here, the influence of shared resources on integration is limited.     

Buyer–supplier relationship's influence on traceability implementation in the vegetable industry

The increasing importance of food safety has made traceability a crucial issue in the agri-business industry. In this article, we have analysed the factors that shape buyer–supplier relationships, and how they influence the traceability of raw materials. In order to do so, first, we have reviewed the literature to develop an analytical framework. Next, we have carried out four case studies on vegetable firms with the purpose of uncovering the variables that characterise buyer–supplier relationships, and their influence on traceability in this sector. Finally, we have compared the observed links with the conceptual framework derived from the literature in order to build an improved model.     

循环经济下的会计控制

循环经济的出现,给企业生产带来了一场革命,也对会计工作提出了新的挑战。本文阐述了循环经济与会计控制的关系,提出了循环经济对会计控制的新要求,阐述了循环经济模式下会计控制内容的扩展以及为适应循环经济的挑战,会计控制应采取的对策。     

Randomized quasi-Monte Carlo methods in pricing securities

Today quasi-Monte Carlo methods are used successfully in computational finance and economics as an alternative to the Monte Carlo method. One drawback of these methods, however, is the lack of a practical way of error estimation. To address this issue several researchers introduced the so-called randomized quasi-Monte Carlo methods in the last decade. In this paper we will present a survey of randomized quasi-Monte Carlo methods, and compare their efficiencies with the efficiency of the Monte Carlo method in pricing certain securities. We will also investigate the effects of Box–Muller and inverse transformation techniques when they are applied to low-discrepancy sequences.     

Shaping buyer–supplier relationships in manufacturing contexts: Design and test of a contingency model

Although the idea that buyer–supplier partnerships can yield considerable benefits to firms is largely diffused among researchers and practitioners, the approach adopted in this paper is that no “one best way” exists in buyer–supplier relationships, but rather a “best way” for each specific exchange context. Hence, this paper proposes a contingency model for shaping and managing buyer–supplier relationships in manufacturing contexts. In order to test the model, an empirical study was performed on a sample of 45 buyer–supplier relationships within the Italian white goods industry. A three-dimensional performance indicator was computed to compare supplier performance achieved within relations matching the model's suggestions with those set differently. The results strongly suggest that suppliers involved in relationships set accordingly to the contingency model are likely to enjoy superior performance.     

A characterization of equilibria in the Groves–Ledyard mechanism

In this paper, we characterize all interior and boundary equilibria of the Groves–Ledyard mechanism for a large class of economies and determine their stability properties. We show that the mechanism admits three types of equilibria: a symmetric, efficient, stable interior equilibrium, a large set of asymmetric, efficient, unstable, interior equilibria, and a large set of asymmetric, inefficient, stable boundary equilibria. We further show that asymmetric equilibria fail to exist for large values of the punishment parameter or if the message space is bounded sufficiently. The boundary equilibria previously had not been located nor had the instability of the asymmetric equilibria been known. Interestingly, the stability of the symmetric equilibrium rests on two dynamics that individually produce instability.     

我国铁路客车空调控制技术研究状况初探

本文在分析我国铁路客车空调控制系统现状的基础上,探讨了客车空调安全运行控制技术和环境品质控制技术的研究状况。     

Estimation in Shewhart control charts: effects and corrections

The influence of the estimation of parameters in Shewhart control charts is investigated. It is shown by simulation and asymptotics that (very) large sample sizes are needed to accurately determine control charts if estimators are plugged in. Correction terms are developed to get accurate control limits for common sample sizes in the in-control situation. Simulation and theory show that the new corrections work very well. The performance of the corrected control charts in the out-of-control situation is studied as well. It turns out that the correction terms do not disturb the behavior of the control charts in the out-of-control situation. On the contrary, for moderate sample sizes the corrected control charts remain powerful and therefore, the recommendation to take at least 300 observations can be reduced to 40 observations when corrected control charts are applied.Acknowledgements. The authors would like to thank Sri Nurdiati for doing the Monte Carlo studies.