Digital robust control law synthesis using constrained optimization

Development of digital robust control laws for active control of high performance flexible aircraft and large space structures is a research area of significant practical importance. The flexible system is typically modeled by a large order state space system of equations in order to accurately represent the dynamics. The active control law must satisy multiple conflicting design requirements and maintain certain stability margins, yet should be simple enough to be implementable on an onboard digital computer. Described here is an application of a generic digital control law synthesis procedure for such a system, using optimal control theory and constrained optimization technique. A linear quadratic Gaussian type cost function is minimized by updating the free parameters of the digital control law, while trying to satisfy a set of constraints on the design loads, responses and stability margins. Analytical expressions for the gradients of the cost function and the constraints with respect to the control law design variables are used to facilitate rapid numerical convergence. These gradients can be used for sensitivity study and may be integrated into a simultaneous structure and control optimization scheme

Selection of proposal distributions for generalized importance sampling estimators

The standard importance sampling (IS) estimator, generally does not work well in examples involving simultaneous inference on several targets as the importance weights can take arbitrarily large values making the estimator highly unstable. In such situations, alternative generalized IS estimators involving samples from multiple proposal distributions are preferred. Just like the standard IS, the success of these multiple IS estimators crucially depends on the choice of the proposal distributions. The selection of these proposal distributions is the focus of this article. We propose three methods based on (i) a geometric space filling coverage criterion, (ii) a minimax variance approach, and (iii) a maximum entropy approach. The first two methods are applicable to any multi-proposal IS estimator, whereas the third approach is described in the context of Doss's (2010) two-stage IS estimator. For the first method we propose a suitable measure of coverage based on the symmetric Kullback-Leibler divergence, while the second and third approaches use estimates of asymptotic variances of Doss's (2010) IS estimator and Geyer's (1994) reverse logistic estimator, respectively. Thus, we provide consistent spectral variance estimators for these asymptotic variances. The proposed methods for selecting proposal densities are illustrated using various detailed examples

Entrepreneurial culture, occupational choice and tax policy

This paper studies the influence of entrepreneurial culture among social groups in an economy. The cultural factor determines their occupational preferences. We develop a model in which a concentration factor has been used as a measure of business culture determining the occupational choice patterns of otherwise identical social groups. The occupational distribution of individuals from different groups is obtained by comparing expected utilities from employment and entrepreneurship. Based on the labor market outcomes the mean income and income variance of different groups is calculated. Individuals from groups with greater cultural traits display higher relative risk aversion with a high income variance compared to other groups. We propose a tax- subsidy policy and obtain conditions for maximizing social utility.Entrepreneurial culture, Self-employment, Risk aversion, Income variance, National Income, Tax-subsidy Policy

Global Climate Change, Technology Transfer and Trade with Complete Specialization

The paper develops a model in which a country with better technology for abatement of Green House Gas (GHG) emission (the North) commits to an international protocol to keep the global GHG emission within a specified limit while it helps the mitigation effort in the other country (the South) with unconditional transfer of abatement technology. It finds out in the autarkic (‘no trade’) equilibrium the technology transfer offer from the North is always accepted by the South. The North may offer either a partial or a complete technology transfer. If partial technology transfer is offered it finds out the determinants of the extent of technology transfer. Then it compares the autarkic equilibrium with equilibrium where trade with complete specialization occurs and finds out that trade limits the scope of technology transfer as an instrument for mitigation of global GHG emission.GHG Emission, Mitigation, Technology Transfer, Trade

Voluntary agreements and community development as CSR in innovation strategies

The present paper examines how an innovating firm decides between two forms of voluntary agreements (VA) in a context, where a non-governmental organization (NGO) rather than a regulator watches over citizens' interests. The innovation generates profit and consumer surplus as well as environmental damage. Corporate social responsibility (CSR) within the innovation process is considered in terms of a redistribution of profit towards community development, with or without additional abatement efforts via a VA. Bargaining between firm and NGO yields the amount allocated to community development. The model demonstrates that the firm's choice of VA hinges on the tradeoffs between appropriating the full innovation profit and paying a higher lump sum towards community development or sacrificing some of the innovation profit by lowering innovation effort, but gaining in terms of paying a lesser amount towards community development. CSR with abatement is unlikely in the case of radical innovations. There is also a clear divergence of interests between the firm, the NGO and the State for some parameter configurations, which are duly identified.Corporate social responsibility, voluntary agreements, community development, donations, innovation

R&D cooperation, asymmetric technological capabilities and rationale for technology parks

Starting from the premise that firms are distinct in terms of their capacity to create radical product innovations, the present paper attempts to explore how firms choose between different forms of R&D cooperation and their consequences for social welfare. It studies a duopolistic market, where firms have to choose between R&D competition, a cost sharing alliance, an information sharing alliance or an R&D cartel. The paper demonstrates that asymmetry has an impact on alliance choice and social welfare. With similar firms, the cost sharing alliance will be preferred to R&D competition or any other form of collaboration. With significant asymmetry no alliance may be formed. In terms of social welfare, any alliance is preferable to R&D competition and the R&D cartel is the best. Given this inherent contradiction between private preferences and optimal social choice, the paper provides a rationale for public investment in terms of science and technology parks to promote R&D cartels. --R&D competition,R&D cooperation,technology parks