Multilevel decomposition approach to the preliminary sizing of a transport aircraft wing

A multilevel/multidisciplinary optimization scheme for sizing an aircraft wing structure is described. A methodology using nonlinear programming in application to a very large engineering problem is presented. This capability is due to the decomposition approach. Over 1300 design variables are considered for this nonlinear optimization task. In addition, a mathematical link is established coupling the detail of structural sizing to the overall system performance objective, such as fuel consumption. The scheme is implemented as a three level system analyzing aircraft mission performance at the top level, the total aircraft structure as the middle level, and individual stiffened wing skin cover panels at the bottom level. Numerical show effectiveness of the method and its good convergence characteristics

Structural optimization by multilevel decomposition

A method is described for decomposing an optimization problem into a set of subproblems and a coordination problem which preserves coupling between the subproblems. The method is introduced as a special case of multilevel, multidisciplinary system optimization and its algorithm is fully described for two level optimization for structures assembled of finite elements of arbitrary type. Numerical results are given for an example of a framework to show that the decomposition method converges and yields results comparable to those obtained without decomposition. It is pointed out that optimization by decomposition should reduce the design time by allowing groups of engineers, using different computers to work concurrently on the same large problem

ISSYS: An integrated synergistic Synthesis System

Integrated Synergistic Synthesis System (ISSYS), an integrated system of computer codes in which the sequence of program execution and data flow is controlled by the user, is discussed. The commands available to exert such control, the ISSYS major function and rules, and the computer codes currently available in the system are described. Computational sequences frequently used in the aircraft structural analysis and synthesis are defined. External computer codes utilized by the ISSYS system are documented. A bibliography on the programs is included

A new algorithm for general multiobjective optimization

Described is a new technique for converting a constrained optimization problem to an unconstrained one, and a new method for multiobjective optimization based on that technique. The technique transforms the objective functions into goal constraints. The goal constraints are appended to the set of behavior constraints and the envelope of all functions in the set is searched for an unconstrained minimum. The technique may be categorized as a SUMT algorithm. In multiobjective applications, the approach has the advantage of locating a compromise minimum without the need to optimize for each individual objective function separately. The constrained to unconstrained conversion is described, followed by a description of the multiobjective problem. Two example problems are presented to demonstrate the robustness of the method

Pengaruh Partisipasi Manajer Terhadap Efektivitas Sistem Informasi Akuntansi

The development of the business environment in globalization era has been triggered an increasingly tight business competition. Every companies who have an established its own strategies to manage a variety of information, human resources, allocation of funds and others. Accounting information system is a great resources that very valuable to an organization for the smoothness management of the company's financial and decision making wheter it is to long term and short term, however there are several aspect that can be a factors the effectiveness of the accounting information system, that is manager's participation. The research is aimed to proves that manager's participation and manager's involvement had a positive influence on the effectiveness of accounting information system (AIS) at manufacturing company, especially in the industrial zone Batamindo Mukakuning Batam City. The research method is using regression analysis to proves are the manager's participation (independent variable) and manager's involvement (independent variable) gives effect to the effectiveness of information system (dependent variable) or not. The result of this research is shows that variable of manager's participation and manager's involvement has a significant influence to the effectiveness of information system. The method is using purposive sampling is done by taking a sampling of the population according to certain criteria

Integrating aerodynamics and structures in the minimum weight design of a supersonic transport wing

An approach is presented for determining the minimum weight design of aircraft wing models which takes into consideration aerodynamics-structure coupling when calculating both zeroth order information needed for analysis and first order information needed for optimization. When performing sensitivity analysis, coupling is accounted for by using a generalized sensitivity formulation. The results presented show that the aeroelastic effects are calculated properly and noticeably reduce constraint approximation errors. However, for the particular example selected, the error introduced by ignoring aeroelastic effects are not sufficient to significantly affect the convergence of the optimization process. Trade studies are reported that consider different structural materials, internal spar layouts, and panel buckling lengths. For the formulation, model and materials used in this study, an advanced aluminum material produced the lightest design while satisfying the problem constraints. Also, shorter panel buckling lengths resulted in lower weights by permitting smaller panel thicknesses and generally, by unloading the wing skins and loading the spar caps. Finally, straight spars required slightly lower wing weights than angled spars

Inverse Estimation of Temperature Profiles in Landfills Using Heat Recovery Fluids Measurements

In addition to leachate and gas emission analysis, temperature variations in municipal solid waste landfills are routinely monitored for safety and health reasons, such as the increased production of biogas or the danger of spontaneous combustion phenomena if the temperature exceeds 70–75°C. The increasing constraints on greenhouse gas emissions and the convenience of fuel and heat recovery have helped develop a global approach to landfills' operation and maintenance, generally referred to as bioreactor landfill management. The heat recovery piping we are presently designing can be a significant part of this approach. The heat gained by a fluid circulated in a closed network through the landfill is transferred to an external heat exchanger or used directly as warm water. Additionally, it can help reduce landfill temperature levels and control biogas generation. Since the pipes diameter is large enough to allow for a radial temperature gradient, this information can be used for an inverse estimation of the temperature profile in the landfill which constitutes the boundary conditions of the resulting heat transfer problem. In this paper, we describe an algorithm for regularising the resulting ill-posed free boundary estimation problem using sampled data of the heat recovery fluid on exiting the landfill

Application of multidisciplinary optimization methods to the design of a supersonic transport

An optimization design method is discussed. This method is based on integrating existing disciplinary analysis and sensitivity analysis techniques by means of generalized sensitivity equations. A generic design system implementing this method is described. The system is being used to design the configuration and internal structure of a supersonic transport wing for optimum performance. This problem combines the disciplines of linear aerodynamics, structures, and performance. Initial results which include the disciplines of aerodynamics and structures in a conventional minimum weight design under static aeroelastic constraints are presented

La fonction de demande de monnaie pour la zone euro : un réexamen.

In recent years, the dynamics of M3 in the euro area have been driven by two factors: a strong preference for liquidity, observed between 2001 and 2003, followed by a normalisation, at a relatively moderate pace, of portfolio behaviour; as regards the counterparts, changes in M3 and net external assets were of comparable magnitude. These factors highlight the role of national and international portfolio shifts in monetary developments. Furthermore, the traditional specifications of the money demand function sometimes yield unsatisfactory results: instability of short and long-term coefficients, relatively large differences between the estimated and actual value of monetary aggregates, and significant changes in the number of long-run relations. Hence the idea of constructing a money demand function that excludes the external counterpart of M3 or, alternatively, introducing financial asset prices in the demand function of M3, as suggested by Friedman (1988). First, the basic equation, based on the quantitative equation of money, was reestimated in order to verify, for example, whether extending the estimation period or revising certain variables would not result in a major change, notably in terms of the stability of the parameters or the number of structural relations. Indeed, this equation exhibits two instabilities (parameters and the number of long-run relations). Similar results are obtained when the external counterpart of M3 is not taken into account. However, by including European share prices, we obtain a substitution effect (significantly negative coefficient) of this variable and a better adjustment, without affecting the two long-run relations (money demand and the Fisher relation) discussed in the article published in Banque de France Monthly Digest No. 113. So, all other things being equal, a decline in European stock market yields would result in a rise in real money holdings and a decrease in the velocity of circulation of money. Equity market developments therefore appear to be a significant explanatory factor for the dynamics of M3 in the euro area. Lastly, estimates of the real money gap, based on the money demand equation factoring in the substitution effect associated with European stock price developments, point to moderate but persistent excess liquidity in the euro area.Money demand ; M3 own rate ; Wealth effect ; Substitution effect.

La fonction de demande de monnaie pour la zone euro : un réexamen.

demande de monnaie, taux intrinsèque, richesse, substitution.