Distributed machining control and monitoring using smart sensors/actuators

The study of smart sensors and actuators led, during the past few years, to the development of facilities which improve traditional sensors and actuators in a necessary way to automate production systems. In an other context, many studies are carried out aiming at defining a decisional structure for production activity control and the increasing need of reactivity leads to the autonomization of decisional levels close to the operational system. We suggest in this paper to study the natural convergence between these two approaches and we propose an integration architecture dealing with machine tool and machining control that enables the exploitation of distributed smart sensors and actuators in the decisional system

Multi-agent framework based on smart sensors/actuators for machine tools control and monitoring

Throughout the history, the evolutions of the requirements for manufacturing equipments have depended on the changes in the customers' demands. Among the present trends in the requirements for new manufacturing equipments, there are more flexible and more reactive machines. In order to satisfy those requirements, this paper proposes a control and monitoring framework for machine tools based on smart sensor, on smart actuator and on agent concepts. The proposed control and monitoring framework achieves machine monitoring, process monitoring and adapting functions that are not usually provided by machine tool control systems. The proposed control and monitoring framework has been evaluated by the means of a simulated operative part of a machine tool. The communication between the agents is achieved thanks to an Ethernet network and CORBA protocol. The experiments (with and without cooperation between agents for accommodating) give encouraging results for implementing the proposed control framework to operational machines. Also, the cooperation between the agents of control and monitoring framework contributes to the improvement of reactivity by adapting cutting parameters to the machine and process states and to increase productivity

A technique for estimating a cost system that allows for inefficiency

The presentation of a new econometric technique for estimating a system of cost and input share equations that allow for inefficiency.Econometrics ; Production (Economic theory)

Is all government capital productive?

Government spending policy ; Production (Economic theory)

Does public capital crowd out private capital? : evidence from India

A recent but rapidly growing empirical literature focuses on the relationship between public and private capital. But for the most part, it ignores the heterogeneity of public investment. In many countries, especially in the developing world, public investment includes not only basic infrastructure projects, but also commercial and industrial projects similar to those undertaken by the private sector. And those two types of public investment are likely to have quite different effects on the accumulation of private capital. Using data from India, the author examines this issue empirically by implementing a simple analytical model encompassing two types of public capital. The empirical results show that in the long run capital for public infrastructure projects crowds in private capital - other types of public capital have the opposite effect. But in the short run, both kinds of public investment may crowd out private investment.Decentralization,Economic Theory&Research,International Terrorism&Counterterrorism,Banks&Banking Reform,Capital Markets and Capital Flows,Inequality,Economic Stabilization,Economic Theory&Research,Environmental Economics&Policies,Banks&Banking Reform

A Comparison of Stochastic Frontier Approaches to Estimating Inefficiency and Total Factor Productivity: An Application to Irish Dairy Farming

This paper compares standard stochastic frontier models for panel data with a number of recently developed models designed to remove unobserved heterogeneity from the inefficiency component. Results are used to construct a generalised Malmquist total factor productivity (TFP) index. We conclude that the choice of approach makes little difference where the purpose of the study is to analyse aggregate trends in TFP and its components. However, where inefficiency estimates and their dispersion are of interest, attention should be paid to how the analyst’s interpretation of inefficiency relates to the underlying assumptions of the model that is used.Efficiency, panel data, total factor productivity, stochastic production frontier, ‘true’ effects models, dairy sector

ECONOMETRIC-PROCESS MODELS FOR INTEGRATED ASSESSMENT OF AGRICULTURAL PRODUCTION SYSTEMS

This paper develops the conceptual and empirical basis for a class of empirical economic production models that can be linked to site-specific bio-physical models for use in integrated assessment research. Site-specific data are used to estimate econometric production models, and these data and models are then incorporated into a simulation model that represents the decision making process of the farmer as a sequence of discrete or continuous land use and input use decisions. This discrete/continuous structure of the econometric process model is able to simulate decision making both within and outside the range of observed data in a way that is consistent with economic theory and with site-specific bio-physical constraints and processes. An econometric-process model of the dryland grain production system of the Northern Plains demonstrates the capabilities of this type of model.bio-physical models, integrated assessment, production models, dryland grain production, econometric-process models, Production Economics, C5, Q1, Q2,

TECHNICAL PROGRESS IN THE SETE TRAWL FISHERY, 1985-1999

Fisheries throughout the world have long been subject to overfishing and excess capacity, which has generated substantial and increasing concern about biological and economic performance ramifications. These problems in part stem from substantial investment in technical improvements to boats and equipment in fishing fleets. Such technical change exacerbates the extent of excess fishing capacity, as well as low returns to fishing effort and investment due to catch limitations from both regulatory constraints and overfished stocks. However, economists have not yet attempted to quantify the extent or effects of technical change in fisheries. In this paper we use detailed data on innovation patterns for 19 vessels in the Sete trawl fleet of Southern France to evaluate the contributions of embodied and disembodied technical change to catch rates. We find that embodied technical change enhanced productivity by approximately 1 percent per year between 1985-99, but that external (disembodied) events counteracted this by causing a net output decline of about 3 percent per year. Neither efficiency nor output composition changes appear to have had a substantive effect on observed performance levels.Research and Development/Tech Change/Emerging Technologies, Resource /Energy Economics and Policy,

The Impact of Vertical Integration and Outsourcing on Firm Efficiency: Evidence from the Italian Machine Tool Industry

In this paper we made use of an econometric approach to efficiency analysis in order to capture the role of vertical integration and outsourcing on firm's efficiency. Vertical integration is considered an indicator of structure, while outsourcing represents the process of its change. We consider inefficiency measures as indicators of organizational heterogeneity, related to the firm's choices regarding the phases of the production process that are under its control. We find support for the hypothesis of a relationship between vertical integration and efficiency. The results on outsourcing activity, and in particular the interaction between outsourcing and vertical structure, indicate that heterogeneous patterns, far from tending to cancel out each other as a consequence of common external changes, are reinforcing. Moreover, the sensitivity of inefficiency variance to the cycle, indicate that different firms may have different dynamic properties

Recovering the sunk costs of R&D: the moulds industry case

Sunk costs for R&D are an important determinant of the level of innovation in the economy. In this paper I recover them using a Markov equilibrium framework. The contribution is twofold. First, a model of industry dynamics which accounts for selection into R&D, capital accumulation and entry/exit is proposed. The industry state is summarized by an aggregate state with the advantage that it avoids the "curse of dimensionality". Second, the estimated sunk costs of R&D for the Portuguese moulds industry are shown to be important (3.4 million Euros). They become particularly relevant since the industry is mostly populated by small firms. Institutional changes in the early 1990s generated an increase in demand from European car makers and created the incentives for firms to pay the costs of investment. Trade-induced innovation reinforced the selection effect by which international trade leads to productivity growth. Finally, using the estimated parameters, simulations evaluate the effects of changes in market size, sunk costs and entry costs