Output model-following control synthesis for an oblique-wing aircraft

Recent interest in oblique-wing aircraft has focused on the potential aerodynamic performance advantage of a variable-skew oblique wing over a conventional or symmetric sweep wing. Unfortunately, the resulting asymmetric configuration has significant aerodynamic and inertial cross-coupling between the aircraft longitudinal and lateral-directional axes. Presented here is a decoupling control law synthesis technique that integrates stability augmentation, decoupling, and the direct incorporation of desired handling qualities into an output feedback controller. The proposed design technique uses linear quadratic regulator concepts in the framework of explicit model following. The output feedback strategy used is a suboptimal projection from the state space to the output space. Dynamics are then introduced into the controller to improve steady-state performance and increase system robustness. Closed-loop performance is shown by application of the control laws to the linearized equations of motion and nonlinear simulation of an oblique-wing aircraft

Bringing the workers' rights back in? : the discourse and politics of fortifying core labour standards through a labour-trade linkage

Throughout the 1990s the International Confederation of Free Trade Unions (ICFTU) conducted a campaign to convince states to institute a linkage between the international labour and trade regimes (also dubbed a social clause): Trading rights granted to countries qua members of the World Trade Organisation (WTO) would be made conditional on their compliance with International Labour Organisation (ILO) core labour standards – i.e., their upholding of the rights that enable workers ‘to claim a fair share of the wealth they have helped to generate’. The proposal was premised on the claim that increasing global competition confers commercial advantages on producers that undercut labour standards, and that this incites a regulatory race to the bottom. With a labour-trade linkage, however, such undercutting would become a commercial liability and presumably unleash a race to the acceptable. While the campaign was the most wide-ranging in the history of the international union movement, it won limited support: Few trade unions or civil society organisations in the developing world rallied behind it, and developing country governments resolutely refused to make the proposal part of the Doha Round negotiations mandate. However, the question is not if the linkage proposal will return to the international debate, but when and on whose terms. The present thesis explores whether and how a labour-trade linkage may help to tackle the challenges that confront labour in developing countries. In so doing, it privileges the viewpoints of activists in Brazil and South Africa. It furthermore pays particular attention to the challenge of realising agricultural workers’ freedom of association and right to collective bargaining (i.e., ‘trade union rights’) in the two countries. The study is organised around three key research questions: First, why were certain influential workers’ rights activists lukewarm towards, if not actively opposed to the linkage idea during the 1990s? Second, to what extent are the trade union rights of South African and Brazilian agricultural workers realised, and how may the present situation be accounted for? Third, what would be the properties of a linkage helping to tackle the challenges that confront Brazilian and South African labour, including in agriculture, and to what extent can a linkage thus conceived be accommodated by the international trade and labour regimes? With regards to the first question, the main finding is that previous attempts at gauging the linkage debate as a showdown between a liberalist and an interventionist discourse ignores that the strength and sources of linkage resistance owed a lot to a pervasive counterhegemonic discourse. This brings into view the principled and practical problems that would follow if labour rights were to be safeguarded by the fair competition logic of WTO. As to the second question, the study finds that agricultural workers, in Brazil and South Africa alike, do not organise themselves to any considerable extent, nor are they in a position to meaningfully affect the terms and conditions of employment through collective bargaining. However, the respective case studies highlight quite different reasons for such poor trade union rights realisation. In the case of Brazil, a corporatist labour relations system in conflict with the relevant ILO conventions plays a considerable role: Significantly, legislation prescribes union monopoly representation in predetermined occupational categories, and this forces agricultural wageworkers to share trade unions with smallholders. This ‘cohabitation’ constitutes a significant obstacle to the organisation and collective bargaining of wageworkers. South Africa’s pluralist labour relations system was borne out of the transition to democracy, is praised by the ILO and trade unionists alike, and the inability of agricultural workers to organise and press collective claims here is not readily attributable to legislation. The fundamental problem relates to enforcement: The system rests on the assumption that progressive labour legislation will suffice to cast rural unions in the role as effective custodians and enforcers of individual workers’ freedom of association. But structural features of the agricultural sector collude with union ineptness to prevent this from happening. When individual workers’ freedom of association is nevertheless taken to be the reserve of trade unions, that freedom is left de facto unprotected. As regards to the third question, the thesis finds that a linkage helping to tackle the challenges that confront Brazilian and South African labour (i) should be part of a wider internationalist labour compromise that heeds not only the protection of rights but also of jobs in developing countries; (ii) should superimpose ILO rule on WTO (not the opposite); (iii) be premised on the use of targeted and positive trade measures; and (iv) should consider how to give traction to the trade union rights of presently unprotected or unorganised workers. The question of political will of governments notwithstanding, the major obstacles to a labourtrade linkage with such properties reside in the make-up of ILO – not WTO.Nordiska Afrikainstitute

How Emission Certificate Allocations Distort Fossil Investments: The German Example

Despite political activities to foster a low-carbon energy transition, Germany currently sees a considerable number of new coal power plants being added to its power mix. There are several possible drivers for this "dash for coal", but it is widely accepted that windfall profits gained through free allocation of ETS certificates play an important role. Yet the quantification of allocation-related investment distortions has been limited to back-of-the envelope calculations and stylized models so far. We close this gap with a numerical model integrating both Germany's particular allocation rules and its specific power generation structure. We find that technology specific new entrant provisions have substantially increased incentives to invest in hard coal plants compared to natural gas at the time of the ETS onset. Expected windfall profits compensated more than half the total capital costs of a hard coal plant. Moreover, a shorter period of free allocations would not have turned investors' favours towards the cleaner natural gas technology because of preexisting economic advantages for coal. In contrast, full auctioning of permits or a single best available technology benchmark would have made natural gas the predominant technology of choice.Emissions trading, Allocation rules, Power markets, Investments

Information transfer in signaling pathways : a study using coupled simulated and experimental data

Background: The topology of signaling cascades has been studied in quite some detail. However, how information is processed exactly is still relatively unknown. Since quite diverse information has to be transported by one and the same signaling cascade (e.g. in case of different agonists), it is clear that the underlying mechanism is more complex than a simple binary switch which relies on the mere presence or absence of a particular species. Therefore, finding means to analyze the information transferred will help in deciphering how information is processed exactly in the cell. Using the information-theoretic measure transfer entropy, we studied the properties of information transfer in an example case, namely calcium signaling under different cellular conditions. Transfer entropy is an asymmetric and dynamic measure of the dependence of two (nonlinear) stochastic processes. We used calcium signaling since it is a well-studied example of complex cellular signaling. It has been suggested that specific information is encoded in the amplitude, frequency and waveform of the oscillatory Ca2+-signal. Results: We set up a computational framework to study information transfer, e.g. for calcium signaling at different levels of activation and different particle numbers in the system. We stochastically coupled simulated and experimentally measured calcium signals to simulated target proteins and used kernel density methods to estimate the transfer entropy from these bivariate time series. We found that, most of the time, the transfer entropy increases with increasing particle numbers. In systems with only few particles, faithful information transfer is hampered by random fluctuations. The transfer entropy also seems to be slightly correlated to the complexity (spiking, bursting or irregular oscillations) of the signal. Finally, we discuss a number of peculiarities of our approach in detail. Conclusion: This study presents the first application of transfer entropy to biochemical signaling pathways. We could quantify the information transferred from simulated/experimentally measured calcium signals to a target enzyme under different cellular conditions. Our approach, comprising stochastic coupling and using the information-theoretic measure transfer entropy, could also be a valuable tool for the analysis of other signaling pathways

Information transfer in signaling pathways : a study using coupled simulated and experimental data

Background: The topology of signaling cascades has been studied in quite some detail. However, how information is processed exactly is still relatively unknown. Since quite diverse information has to be transported by one and the same signaling cascade (e.g. in case of different agonists), it is clear that the underlying mechanism is more complex than a simple binary switch which relies on the mere presence or absence of a particular species. Therefore, finding means to analyze the information transferred will help in deciphering how information is processed exactly in the cell. Using the information-theoretic measure transfer entropy, we studied the properties of information transfer in an example case, namely calcium signaling under different cellular conditions. Transfer entropy is an asymmetric and dynamic measure of the dependence of two (nonlinear) stochastic processes. We used calcium signaling since it is a well-studied example of complex cellular signaling. It has been suggested that specific information is encoded in the amplitude, frequency and waveform of the oscillatory Ca2+-signal. Results: We set up a computational framework to study information transfer, e.g. for calcium signaling at different levels of activation and different particle numbers in the system. We stochastically coupled simulated and experimentally measured calcium signals to simulated target proteins and used kernel density methods to estimate the transfer entropy from these bivariate time series. We found that, most of the time, the transfer entropy increases with increasing particle numbers. In systems with only few particles, faithful information transfer is hampered by random fluctuations. The transfer entropy also seems to be slightly correlated to the complexity (spiking, bursting or irregular oscillations) of the signal. Finally, we discuss a number of peculiarities of our approach in detail. Conclusion: This study presents the first application of transfer entropy to biochemical signaling pathways. We could quantify the information transferred from simulated/experimentally measured calcium signals to a target enzyme under different cellular conditions. Our approach, comprising stochastic coupling and using the information-theoretic measure transfer entropy, could also be a valuable tool for the analysis of other signaling pathways

Decoupling control synthesis for an oblique-wing aircraft

Interest in oblique-wing aircraft has surfaced periodically since the 1940's. This concept offers some substantial aerodynamic performance advantages but also has significant aerodynamic and inertial cross-coupling between the aircraft longitudinal and lateral-directional axes. This paper presents a technique for synthesizing a decoupling controller while providing the desired stability augmentation. The proposed synthesis procedure uses the concept of a real model-following control system. Feedforward gains are selected on the assumption that perfect model-following conditions are satisfied. The feedback gains are obtained by using eigensystem assignment, and the aircraft is stabilized by using partial state feedback. The effectiveness of the control laws developed in achieving the desired decoupling is illustrated by application to linearized equations of motion of an oblique-wing aircraft for a given flight condition

Can the Green Economy deliver it all? Experiences of renewable energy policies with socio-economic objectives

The Green Economy (GE) paradigm aims to reconcile environmental and socio-economic objectives. Policies to deploy renewable energy (RE) are widely perceived as a way to tap the potential synergies of these objectives. It is, however, still largely unclear whether the potential of simultaneously achieving both environmental and socio-economic objectives can be fully realized, and whether and how multiple objectives influence policy design, implementation, and evaluation. We aim to contribute to this aspect of GE research by looking at selected country experiences of renewable energy deployment with respect to the socio-economic goals of job creation or energy access. Across the cases examined, we find the following implications of relevance for the GE framework: First, we confirm the important role of governmental action for GE, with the specific need to state objectives clearly and build monitoring capacity. Second, consistent with the “strong” green growth variant of GE, some of the cases suggest that while renewable deployment may indeed lead to short-term socio-economic benefits, these benefits may not last. Third, we underline the urgent need for new methodologies to analyze and better understand multiple-objective policies, which are at the heart of the GE paradigm

Transition from stochastic to deterministic behavior in calcium oscillations

Simulation and modeling is becoming more and more important when studying complex biochemical systems. Most often, ordinary differential equations are employed for this purpose. However, these are only applicable when the numbers of participating molecules in the biochemical systems are large enough to be treated as concentrations. For smaller systems, stochastic simulations on discrete particle basis are more accurate. Unfortunately, there are no general rules for determining which method should be employed for exactly which problem to get the most realistic result. Therefore, we study the transition from stochastic to deterministic behavior in a widely studied system, namely the signal transduction via calcium, especially calcium oscillations. We observe that the transition occurs within a range of particle numbers, which roughly corresponds to the number of receptors and channels in the cell, and depends heavily on the attractive properties of the phase space of the respective systems dynamics. We conclude that the attractive properties of a system, expressed, e.g., by the divergence of the system, are a good measure for determining which simulation algorithm is appropriate in terms of speed and realism

Starting low, reaching high? : Sequencing in EU climate and energy policies

In order to achieve the UNFCCC Paris Agreement goals, climate policies worldwide require considerable ratcheting-up. Policy sequencing provides a framework for analysing policy process dynamics that facilitate ratcheting-up. We apply a sequencing perspective to two key EU climate and energy policies, the Emissions Trading Scheme (ETS) and the Renewable Energy Directive (RED), to comparatively test the empirical relevance of sequencing for single policies - in addition to sequencing across policies, which has been the focus of sequencing theory so far - and to uncover specific mechanisms. Our results confirm that sequencing, based on triggering positive and controlling negative feedback, is relevant both within and across policies. Policy choices that may facilitate ratcheting-up include tools to control costs, the possibility to centralise and harmonise in a multi-level governance context, options for compensation of reluctant actors, and the encouragement of learning processes