Hardware/Software Co-design of Communication Protocols

An important aspect in providing high performance distributed systems such as multimedia systems is the combined use of hardware and software in the end systems. System design techniques should allow hardware/software co-design to integrate both means of implementation. In this paper, we show how the standardized formal language Estelle can be used to facilitate co-design. The system will first be designed in Estelle. At the point in time of final decision on which parts to implement in software and which in hardware, the original specification will be split into several partial specifications. The software parts are translated into C code, while the hardware parts are translated into VHDL code for further analysis and development. We present a tool environment which supports the protocol developer in the design and implementation process. A simple Video-on-Demand example shows the usefulness of the tool environment

What makes industries believe in formal methods

The introduction of formal methods in the design and development departments of an industrial company has far reaching and long lasting consequences. In fact it changes the whole environment of methods, tools and skills that determine the design culture of that company. A decision to replace current design practice by formal methods, therefore, appears a vital one and is not lightly taken. The past has shown that efforts to introduce formal methods in industry has faced a lot of controversy and opposition at various hierarchical levels in companies, resulting in a marginal spread of such methods. This paper revisits the requirements for formal description techniques and identifies some critical success and inhibiting factors associated with the introduction of formal methods in the industrial practice. One of the inhibiting factors is the often encountered lack of appropriateness of the formal model to express and manipulate the design concerns that determine the world of the engineer. This factor motivated our research in the area of architectural and implementation design concepts. The last two sections of this paper report on some results of this research

Intercomparison of spectroradiometers and Sun photometers for the determination of the aerosol optical depth during the VELETA-2002 field campaign

[ 1] In July 2002 the VELETA-2002 field campaign was held in Sierra Nevada ( Granada) in the south of Spain. The main objectives of this field campaign were the study of the influence of elevation and atmospheric aerosols on measured UV radiation. In the first stage of the field campaign, a common calibration and intercomparison between Licor-1800 spectroradiometers and Cimel-318 Sun photometers was performed in order to assess the quality of the measurements from the whole campaign. The intercomparison of the Licor spectroradiometers showed, for both direct and global irradiances, that when the comparisons were restricted to the visible part of the spectrum the deviations were within the instruments' nominal accuracies which allows us to rely on these instruments for measuring physical properties of aerosols at the different measurement stations. A simultaneous calibration on AOD data was performed for the Cimel-318 Sun photometers. When a common calibration and methodology was applied, the deviation was lowered to much less than 0.01 for AOD. At the same time an intercomparison has been made between the AOD values given by the spectroradiometers and the Sun photometers, with deviations obtained from 0.01 to 0.03 for the AOD in the visible range, depending on the channel. In the UVA range, the AOD uncertainty was estimated to be around 0.02 and 0.05 for Cimel and Licor respectively. In general the experimental differences were in agreement with this uncertainty estimation. In the UVB range the AOD measurements should not be used due to maximum instrumental uncertainties

Crowd-out, Adverse Selection and Information in Annuity Markets: Evidence from a New Retrospective Data Set in Chile

Annuitization is often considered a socially desirable payout mode from pension plans, because it provides a lifelong income stream and therefore ensures that retirees will not run out of money. However, annuitization is rare in most countries. This project examines workers’ choices during the payout stage in Chile, the only country that has had mandatory personal accounts long enough to have had substantial experience with payouts. Upon retirement, workers in Chile have limited options for payouts: they must either annuitize or take gradual withdrawal. Two-thirds have annuitized. We expect that retirees are less likely to annuitize if their accumulation finances a pension in the vicinity of the minimum pension, whose value is guaranteed by the state. In that case, publiclyfinanced longevity insurance is likely to crowd out private annuity insurance. We expect that retirees with health problems are also less likely to annuitize, possibly leading to adverse selection. Finally, we expect that individuals with greater risk aversion, smaller time preference and better knowledge about the system are more likely to annuitize. A new retrospective data set from Chile yields evidence that is broadly consistent with these hypotheses.

Social Security Rules and Labor Force Participation of Older Workers: Evidence from Chile

Recent research has argued that incentives stemming from social security systems influence the worker’s decision to retire. The experience of Chile, which radically changed its system in 1981, offers an opportunity to test this hypothesis. The new system tightened access to early pensions, replaced an actuarially unfair defined benefit plan with an actuarially fair defined contribution plan, exempted pensioners from the pension payroll tax and allowed widows to keep their own pension in addition to their survivor’s benefit. Although the old system is being phased out, since 1981 the two systems have co-existed. Using probit analysis of the behavior of a retrospective sample of new and old system affiliates, we estimate the impact of the new social security rules on the probability of dropping out of the labor force, for older workers. We find large effects. Age of pensioning has been postponed. Labor force participation is much higher among affiliates of the new system compared with the old, especially for pensioners and women. This is not simply due to selection: Aggregate participation rates have increased as the new system’s share of total affiliates has risen.

Using formal description technique ESTELLE for manufacturing systems specification or description

Usually the description of a system is given in natural language or in diagrams. It is very hard to make this kind of informal description clear, concise and unambiguous. Implementations based on informal specifications are usually prone to errors, omissions and incompatibilities. This paper presents an attempt to introduce Formal Description Techniques (FDT's), originally developed for the area of telecommunications and data transfer, as a mean for the specification/description of manufacturing systems. A brief introduction on standard FDT's, LOTOS, ESTELLE and SDL is given. Several concepts were behind the development of these techniques and this paper exploits the extended finite state machine (EFSM) concept as a suitable form for specification/description of manufacturing systems using FDT ESTELLE

Tool based supporting collaborative design from specification development to CAD modelling

International audienceManagement of dynamic information interdependencies and as well as management of multiple perspectives from specification development to conceptual design, as well as from conceptual design to detailed design are critical elements of collaborative and distributed design. Supporting collaborative design with computer technology is a strategy to enhance the ability of actors to interact with each other and with computational resources during different phases of product design and development. However, many observations from the industry and research support the evidence that both specification development phase and conceptual design are poorly supported by collaborative tools. Furthermore, though CAD tools support detail design, it is imperative to develop new collaborative design tools or renovate traditional standalone CAD systems by making it collaborative-native. Consequently, the first goal of this paper is to propose the development of collaborative tools related to the conceptual design. The second goal is the development of a mechanism for communication between the developed collaborative conceptual design tools and actually CAD tools. The mechanism and architecture of the developed tool for collaborative conceptual design is presented. A design problem illustrates the concepts discussed in the paper

Reconsidering the Demand for Municipal Public Goods Specification : Evidence from French Municipalities

Following Bergtrom and Goodman (1973), this paper can be integrated in the set of studies that have estimated the demand for municipal public services. The main innovation in this paper is methodological as we use a Stone Geary utility function to describe the median voter preferences. Unlike previous studies, we are able to derive the local public expenditure function in a (simplified) linear expenditure system, directly from the theoretical framework. The linear expenditure system provides an estimate of the portion of the incompressible public expenditure in each municipality. Using cross sectional municipal data from France, it is found to be 30% of the total per capita expenditure. Compared to the specification generally used in the literature, linear expenditure system shows a greater sensitivity to price and income variations and reveal a greater number of significant variables.Demand for local public services, Median voter, Linear expenditure system, Nonlinear least squares

Advances in architectural concepts to support distributed systems design

This paper presents and discusses some architectural concepts for distributed systems design. These concepts are derived from an analysis of limitations of some currently available standard design languages. We conclude that language design should be based upon the careful consideration of architectural concepts. This paper aims at supporting designers by presenting a methodological design framework in which they can reason about the design and implementation of distributed systems. The paper is also meant for language developers and formalists by presenting a collection of architectural concepts which deserve consideration for formal support