Environmental problems and economic development in an endogenous fertility model

Population growth is often viewed as a most oppressive global problem with respect to environmental deterioration, but the relationships between population development, economic dynamics and environmental pollution are complex due to various feedback mechanisms. We analyze society’s economic decisions on birth rates, investment into human and physical capital, and polluting emissions within an optimal control model of the coupled demographic-economic-environmental system. We show that a long-run steady state is optimal that is characterized by a stable pollution stock, and by population and economic growth rates depending on the possibilities of emission abatement and technical progress due to human capital accumulation. We derive a condition on the production technologies and opportunity costs of raising children, under which the optimal birth rate is constant even during the transition to a steady state. In particular in an economy where only human capital is needed to produce output, the optimal choice of the birth rate is not affected by the states of the economy or the environment. In such a setting, the optimal birth rate is constant and policy should concentrate on intertemporal adjustment of per-capita emissions.sustainability, endogenous fertility, externalities

Effective risk governance for environmental policy making: a knowledge management perspective

Effective risk management within environmental policy making requires knowledge on natural, economic and social systems to be integrated; knowledge characterised by complexity, uncertainty and ambiguity. We describe a case study in a (UK) central government department exploring how risk governance supports and hinders this challenging integration of knowledge. Forty-five semi-structured interviews were completed over a two year period. We found that lateral knowledge transfer between teams working on different policy areas was widely viewed as a key source of knowledge. However, the process of lateral knowledge transfer was predominantly informal and unsupported by risk governance structures. We argue this made decision quality vulnerable to a loss of knowledge through staff turnover, and time and resource pressures. Our conclusion is that the predominant form of risk governance framework, with its focus on centralised decision-making and vertical knowledge transfer is insufficient to support risk-based, environmental policy making. We discuss how risk governance can better support environmental policy makers through systematic knowledge management practices

Der Diskurs über Nachhaltigkeit und die Rolle der ökologischen Ökonomie

Der Autor erörtert den Zusammenhang zwischen Gesellschaft und Umwelt aus wissenschafts- und wirtschaftssoziologischer Perspektive und geht insbesondere auf die Ansätze der ökologischen Ökonomie ein. Diese hat sich in Abgrenzung zu der von ihr als neoklassisch bezeichneten Umweltökonomie in den 1090er Jahren international etabliert. Sie hat in theoretischer Hinsicht die relevanten Konfliktlinien in der Selbstbeschreibung des ökonomischen Systems aufgezeigt. Die wissenschaftssoziologische Fragestellung eröffnet gegenüber einer rein wirtschaftssoziologischen Betrachtung die Möglichkeit, die theoretische Selbstbeschreibung der Wirtschaft in zwei Richtungen empirisch zu befragen: Sie kann zum einen untersuchen, wie ökologisches Wissen vom Markt adaptiert wird. Zum anderen kann sie aber auch Widersprüche der theoretischen Selbstbeschreibung beobachten und diese unter Berücksichtigung sozialer Fakten soziologisch verstehen. Dieses soziologische Verstehen, d.h. die makrotheoretische Kontextualisierung, entzieht sich aber regelmäßig der Selbstreflektion der Ökonomik. Dennoch kann von einer relativen Autonomie der Ökonomik gegenüber ihrem Gegenstandsbereich ausgegangen werden, was sich - wie der Autor in seinem Beitrag näher zeigt - als systemische Reflexion auf die ökologische Krise verstehen lässt. (ICI2

Application of a Broadband Active Vibration Control System to a Helicopter Trim Panel

This paper discusses testing of a broadband active vibration control concept on an interior trim panel in a helicopter cabin mockup located at ONERA's Centre de Toulouse. The control system consisted of twelve diamond-shaped piezoelectric actuators distributed around a 1.2m x 1.2m trim panel. Accelerometers were mounted at the four vertices of each diamond. The aspect ratio of the diamond was based on the dielectric constants of the piezoelectric material in order to create an actuator-sensor pair that was collocated over a broad frequency range. This allowed robust control to be implemented using simple, low power analog electronics. Initial testing on a thick acrylic window demonstrated the capability of the controller, but actuator performance was less satisfactory when mounted on a composite sandwich trim panel. This may have been due to the orthotropic nature of the trim panel, or due to its much higher stiffness relative to the acrylic window. Insights gained from a finite element study of the actuator-sensor-structural system are discussed

Increasing reliability by means of efficient configurations for high redundancy actuators

A high redundancy actuator (HRA) is composed of a high number of actuation elements, increasing both the travel and the force above the capability of an individual element. This provides inherent fault tolerance: if one of the elements fails, the capabilities of the actuator may be reduced, but it does not become dysfunctional. This paper analyses the likelihood of reductions in capabilities. The actuator is considered as a multi-state system, and the approach for k-out-of-n:G systems can be extended to cover the case of the HRA. The result is a probability distribution that quantifies the capability of the HRA. By comparing the distribution for different configurations, it is possible to identify the optimal configuration of an HRA for a given situation

Analysing the reliability of actuation elements in series and parallel configurations for high-redundancy actuation

A high-redundancy actuator (HRA) is an actuation system composed of a high number of actuation elements, increasing both travel and force above the capability of an individual element. This approach provides inherent fault tolerance: if one of the elements fails, the capabilities of the whole actuator may be reduced, but it retains core functionality. Many different configurations are possible, with different implications for the actuator capability and reliability. This article analyses the reliability of the HRA based on the likelihood of an unacceptable reduction in capability. The analysis of the HRA is a highly structured problem, but it does not fit into known reliability categories (such as the k-out-of-n system), and a fault-tree analysis becomes prohibitively large. Instead, a multi-state systems approach is pursued here, which provides an easy, concise and efficient reliability analysis of the HRA. The resulting probability distribution can be used to find the optimal configuration of an HRA for a given set of requirements

Eine allgemeine Theorie der Bestände

Im vorliegenden Aufsatz wird ein Begriffskonzept entwickelt, das zum besseren Verständnis des Zusammenspiels der Dynamiken von Ökosystemen und Wirtschaft dient: das Konzept des Bestandes. Der Bestandsbegriff wird allgemein mengentheoretisch formuliert. Die zentrale Eigenschaft eines Bestandes liegt in seiner zeitlichen Dauerhaftigkeit. Damit eignen sich Bestände zur Abbildung von Einflüssen, die die Vergangenheit von Systemen auf deren Gegenwart ausübt, und damit zur Analyse von zeitlichen Entwicklungen. Da Beständigkeit eine Eigenschaft in der Zeit darstellt, ist das Konzept des Bestandes nicht spezifisch auf den Gegenstandsbereich einzelner wissenschaftlicher Disziplinen beschränkt und so für die interdisziplinäre Analyse geeignet. Der Begriff wird auf ökonomische und ökologische Beispiele angewandt und dabei auf stochastische Mengen verallgemeinert. Durch die Abgrenzung der Bestandsperspektive von einer Systemsicht kann die hierarchische Struktur realer ökologisch-ökonomischer Systeme analysiert werden. Die Theorie der Bestände stellt einen Baustein für die konzeptionellen Grundlagen der Ökologischen Ökonomie dar. --Dynamik,Beständigkeit,System,Zeitskalen,Population,Persistenz