Synchronization in a population of oscillators

Nowadays a lot of interest in Systems Theory is directed to problems in which separate systems are coupled to each other. We study the dynamics of a population of uniformly all-to-all coupled limit cycle oscillators. The oscillators are permitted to possess different natural frequencies. Our greatest interest goes out to the synchronization of such populations consisting of finitely many oscillators. This synchronized behaviour is only present if the strength of the interactions supersedes some threshold value. We try to obtain some stability properties of this behaviour

Vehicle platoons through ring coupling

In this paper, a novel strategy for the control of a string of vehicles is designed. The vehicles are coupled in a unidirectional ring at the interaction level: each vehicle is influenced by the position of its immediate forward neighbor; the first vehicle in the platoon is influenced by the position of the last vehicle. Through these interactions a cooperative behavior emerges and a platoon of vehicles moving at a constant velocity with constant inter-vehicle spacings is formed. This contrasts with more traditional control schemes where an independent leader vehicle is followed by the remaining vehicles. For this control structure, stability properties are established. The concept of string stability of a platoon is discussed and applied to the ring interconnection. Design rules are presented, showing how an appropriate choice of parameter values leads to a constant spacing or constant time headway policy. Furthermore, the scheme has a characteristic property: it maintains the platoon structure when subject to malfunctioning vehicles

Vehicle platoons with ring coupling

We design a control strategy for platoons of identical vehicles. It is assumed that each vehicle measures the distance with its immediate forward neighbor. The lead vehicle in the platoon only receives information on the position of the last vehicle in the platoon. The resulting behavior of the system is a platoon of vehicles moving at a constant velocity with constant distance between pairs of consecutive vehicles. For a class of identical controllers this solution is asymptotically stable for sufficiently small coupling strength. The concept of string stability of a platoon is discussed and applied to the proposed interconnection. Simulations show the system is well-behaved with respect to string stability. To improve the behavior, integral action is added between the first and last vehicle of the platoon. The resulting behavior is determined and its stability properties are discussed

Going beyond instrument interactions: towards a more comprehensive policy mix conceptualization for environmental technological change

Reaching a better understanding of the policies and politics of transitions presents a main agenda item in the emerging field of sustainability transitions. One important requirement for these transitions, such as the move towards a decarbonized energy system, is the redirection and acceleration of technological change, for which policies play a key role. Several studies of policies supporting environmental technological change have argued for the need to combine different policy instruments in so-called policy mixes. However, existing policy mix studies often fall short of reflecting the complexity and dynamics of actual policy mixes and the underlying politics of (re)designing them. In this paper we take a first step towards a more comprehensive, interdisciplinary policy mix concept for environmental technological change based on a review of the bodies of literature on innovation studies, environmental economics and policy analysis. The concept introduces a clear terminology and consists of the three building blocks elements, processes and characteristics, which can be delineated by several dimensions. Throughout the paper, we illustrate the concept using the example of the policy mix for fostering the transition of the German energy system to renewable power generation technologies. We argue that the proposed concept provides an integrating analytical framework for empirical studies analyzing the impact of the policy mix on environmental technological change and sustainability transitions more broadly. Finally, we derive policy implications and suggest avenues for future research

EU Emission trading – better job second time around?

The EU Emission Trading Scheme (EU ETS) for CO2-emissions from energy and industry installations reflects a paradigm shift towards market-based instruments for environmental policy in the EU. The centerpieces of the EU ETS are National Allocation Plans (NAPs), which individual Member States (MS) design for each phase. NAPs state the total quantity of allowances available in each period (ET-budget) and determine how MS allocate allowances to individual installations. The NAPs thus govern investments and innovation in energy efficient technologies and the energy sector. In terms of distribution, they predetermine winners and losers. In this paper we analyze and evaluate 25 NAPs submitted to the European Commission (EC) for phase 2 (2008-2012) of the EU ETS. At the macro level,we assess whether the submitted ET-budgets are stringent, and whether they imply a cost-efficient split of the required emission reductions between the EU ETS sectors (energy and industry) and the remaining sectors (transportation, tertiary and households). Comparing the submitted ET-budgets with those already approved by the EC suggests that the EC’s decisions significantly improved the effectiveness and economic efficiency of the EU ETS. But given the high share of Kyoto Mechanisms companies are allowed to use, the EU ETS is unlikely to require substantial emission reductions within the EU. At the micro level, we assess (across countries and phases) the allocation methods for existing and new installations, for closures and for clean technologies. A comparison of the NAPs for the second phase and the first phase (2005-2007) provides insights into the (limited) adaptability and flexibility of the scheme. The findings provide guidance for the future design of the EU ETS and applications to other sectors and regions

Consensus over ring networks as a quadratic optimal control problem

This paper presents the consensus problem in the framework of optimal control. Our aim is to synchronize a set of identical linear systems. We propose a cost which penalizes mutual differences between the states of these systems. The feedback matrix resulting from this linear quadratic control problem represents the interconnection network which synchronizes the systems. In general the interconnection structure is of the all-to-all type. We show that it is possible to devise an LQR problem in which the cost results in an interconnection structure representing ring coupling. Care has to be taken that the effect of the feedback control is restricted to synchronizing the systems, i.e. when the systems are synchronized, the feedback control signal is required to be equal to zero

Stability and control characteristics for the inner mold line configuration of the space shuttle orbiter (OA110)

Experimental aerodynamic investigations were conducted on a sting mounted 0.0405-scale representation of the -140A/B inner mold line (IML) space shuttle orbiter in 7.75 x 11 foot low speed wind tunnel, during the time period from 18 March 1974 to 20 March 1974. The primary test objectives were to establish basic longitudinal and lateral-directional stability and control characteristics for the IML orbiter. Additional configurations investigated were sealed elevon hingeline gaps, sealed rudder split line and hingeline gaps, larger radius leading edge on the vertical tail, and sealed speedbrake base. Aerodynamic force and moment data for the orbiter were measured in the body-axis system by an internally mounted, six-component strain gage balance. The model was sting mounted with the center of rotation located at approximately the wing trailing edge. The nominal angle of attack range was from -4 to +30 degrees. Yaw polars were recorded over a nominal yaw angle range from -14 to +14 degrees at constant angles of attack of 0, + or - 5, 10, 15 and 20 degrees