Measurement of transmitted power in untapered multifibre unions oscillatory spectral behaviour

Shows a new structure, the untapered multifibre union, with similar oscillation behaviour to that of tapered single-mode fibres. As a consequences conical regions are not relevant to the final results. This oscillatory behaviour opens the way to low-cost all-fibre devices such as optical filters

Wide bandwidth envelope trackers with reduced switching frequency for RF power amplifier

El requerimiento de proveer alta frecuencia de datos en los modernos sistema de comunicación inalámbricos resulta en complejas señales moduladas de radio-frequencia (RF) con un gran ancho de banda y alto ratio pico-promedio (PAPR). Para garantizar la linealidad del comportamiento, los amplificadores lineales de potencia comunes funcionan típicamente entre 4 y 10 dB de back-o_ desde la máxima potencia de salida, ocasionando una baja eficiencia del sistema. La eliminación y restauración de la evolvente (EER) y el seguimiento de la evolvente (ET) son dos prometedoras técnicas para resolver el problema de la eficiencia. Tanto en EER como en ET, es complicado diseñar un amplificador de potencia que sea eficiente para señales de RF de alto ancho de banda y alto PAPR. Una propuesta común para los amplificadores de potencia es incluir un convertidor de potencia de muy alta eficiencia operando a frecuencias más altas que el ancho de banda de la señal RF. En este caso, la potencia perdida del convertidor ocasionado por la alta frecuencia desaconseja su práctica cuando el ancho de banda es muy alto. La solución a este problema es el enfoque de esta disertación que presenta dos arquitecturas de amplificador evolvente: convertidor híbrido-serie con una técnica de evolvente lenta y un convertidor multinivel basado en un convertidor reductor multifase con control de tiempo mínimo. En la primera arquitectura, una topología híbrida está compuesta de una convertidor reductor conmutado y un regulador lineal en serie que trabajan juntos para ajustar la tensión de salida para seguir a la evolvente con precisión. Un algoritmo de generación de una evolvente lenta crea una forma de onda con una pendiente limitada que es menor que la pendiente máxima de la evolvente original. La salida del convertidor reductor sigue esa forma de onda en vez de la evolvente original usando una menor frecuencia de conmutación, porque la forma de onda no sólo tiene una pendiente reducida sino también un menor ancho de banda. De esta forma, el regulador lineal se usa para filtrar la forma de onda tiene una pérdida de potencia adicional. Dependiendo de cuánto se puede reducir la pendiente de la evolvente para producir la forma de onda, existe un trade-off entre la pérdida de potencia del convertidor reductor relacionada con la frecuencia de conmutación y el regulador lineal. El punto óptimo referido a la menor pérdida de potencia total del amplificador de evolvente es capaz de identificarse con la ayuda de modelo preciso de pérdidas que es una combinación de modelos comportamentales y analíticos de pérdidas. Además, se analiza el efecto en la respuesta del filtro de salida del convertidor reductor. Un filtro de dampeo paralelo extra es necesario para eliminar la oscilación resonante del filtro de salida porque el convertidor reductor opera en lazo abierto. La segunda arquitectura es un amplificador de evolvente de seguimiento de tensión multinivel. Al contrario que los convertidores que usan multi-fuentes, un convertidor reductor multifase se emplea para generar la tensión multinivel. En régimen permanente, el convertidor reductor opera en puntos del ciclo de trabajo con cancelación completa del rizado. El número de niveles de tensión es igual al número de fases de acuerdo a las características del entrelazamiento del convertidor reductor. En la transición, un control de tiempo mínimo (MTC) para convertidores multifase es novedosamente propuesto y desarrollado para cambiar la tensión de salida del convertidor reductor entre diferentes niveles. A diferencia de controles convencionales de tiempo mínimo para convertidores multifase con inductancia equivalente, el propuesto MTC considera el rizado de corriente por cada fase basado en un desfase fijo que resulta en diferentes esquemas de control entre las fases. La ventaja de este control es que todas las corrientes vuelven a su fase en régimen permanente después de la transición para que la siguiente transición pueda empezar muy pronto, lo que es muy favorable para la aplicación de seguimiento de tensión multinivel. Además, el control es independiente de la carga y no es afectado por corrientes de fase desbalanceadas. Al igual que en la primera arquitectura, hay una etapa lineal con la misma función, conectada en serie con el convertidor reductor multifase. Dado que tanto el régimen permanente como el estado de transición del convertidor no están fuertemente relacionados con la frecuencia de conmutación, la frecuencia de conmutación puede ser reducida para el alto ancho de banda de la evolvente, la cual es la principal consideración de esta arquitectura. La optimización de la segunda arquitectura para más alto anchos de banda de la evolvente es presentada incluyendo el diseño del filtro de salida, la frecuencia de conmutación y el número de fases. El área de diseño del filtro está restringido por la transición rápida y el mínimo pulso del hardware. La rápida transición necesita un filtro pequeño pero la limitación del pulso mínimo del hardware lleva el diseño en el sentido contrario. La frecuencia de conmutación del convertidor afecta principalmente a la limitación del mínimo pulso y a las pérdidas de potencia. Con una menor frecuencia de conmutación, el ancho de pulso en la transición es más pequeño. El número de fases relativo a la aplicación específica puede ser optimizado en términos de la eficiencia global. Otro aspecto de la optimización es mejorar la estrategia de control. La transición permite seguir algunas partes de la evolvente que son más rápidas de lo que el hardware puede soportar al precio de complejidad. El nuevo método de sincronización de la transición incrementa la frecuencia de la transición, permitiendo que la tensión multinivel esté más cerca de la evolvente. Ambas estrategias permiten que el convertidor pueda seguir una evolvente con un ancho de banda más alto que la limitación de la etapa de potencia. El modelo de pérdidas del amplificador de evolvente se ha detallado y validado mediante medidas. El mecanismo de pérdidas de potencia del convertidor reductor tiene que incluir las transiciones en tiempo real, lo cual es diferente del clásico modelos de pérdidas de un convertidor reductor síncrono. Este modelo estima la eficiencia del sistema y juega un papel muy importante en el proceso de optimización. Finalmente, la segunda arquitectura del amplificador de evolvente se integra con el amplificador de clase F. La medida del sistema EER prueba el ahorro de energía con el amplificador de evolvente propuesto sin perjudicar la linealidad del sistema. ABSTRACT The requirement of delivering high data rates in modern wireless communication systems results in complex modulated RF signals with wide bandwidth and high peak-to-average ratio (PAPR). In order to guarantee the linearity performance, the conventional linear power amplifiers typically work at 4 to 10 dB back-off from the maximum output power, leading to low system efficiency. The envelope elimination and restoration (EER) and envelope tracking (ET) are two promising techniques to overcome the efficiency problem. In both EER and ET, it is challenging to design efficient envelope amplifier for wide bandwidth and high PAPR RF signals. An usual approach for envelope amplifier includes a high-efficiency switching power converter operating at a frequency higher than the RF signal's bandwidth. In this case, the power loss of converter caused by high switching operation becomes unbearable for system efficiency when signal bandwidth is very wide. The solution of this problem is the focus of this dissertation that presents two architectures of envelope amplifier: a hybrid series converter with slow-envelope technique and a multilevel converter based on a multiphase buck converter with the minimum time control. In the first architecture, a hybrid topology is composed of a switched buck converter and a linear regulator in series that work together to adjust the output voltage to track the envelope with accuracy. A slow envelope generation algorithm yields a waveform with limited slew rate that is lower than the maximum slew rate of the original envelope. The buck converter's output follows this waveform instead of the original envelope using lower switching frequency, because the waveform has not only reduced slew rate but also reduced bandwidth. In this way, the linear regulator used to filter the waveform has additional power loss. Depending on how much reduction of the slew rate of envelope in order to obtain that waveform, there is a trade-off between the power loss of buck converter related to the switching frequency and the power loss of linear regulator. The optimal point referring to the lowest total power loss of this envelope amplifier is identified with the help of a precise power loss model that is a combination of behavioral and analytic loss model. In addition, the output filter's effect on the response is analyzed. An extra parallel damping filter is needed to eliminate the resonant oscillation of output filter L and C, because the buck converter operates in open loop. The second architecture is a multilevel voltage tracking envelope amplifier. Unlike the converters using multi-sources, a multiphase buck converter is employed to generate the multilevel voltage. In the steady state, the buck converter operates at complete ripple cancellation points of duty cycle. The number of the voltage levels is equal to the number of phases according the characteristics of interleaved buck converter. In the transition, a minimum time control (MTC) for multiphase converter is originally proposed and developed for changing the output voltage of buck converter between different levels. As opposed to conventional minimum time control for multiphase converter with equivalent inductance, the proposed MTC considers the current ripple of each phase based on the fixed phase shift resulting in different control schemes among the phases. The advantage of this control is that all the phase current return to the steady state after the transition so that the next transition can be triggered very soon, which is very favorable for the application of multilevel voltage tracking. Besides, the control is independent on the load condition and not affected by the unbalance of phase current. Like the first architecture, there is also a linear stage with the same function, connected in series with the multiphase buck converter. Since both steady state and transition state of the converter are not strongly related to the switching frequency, it can be reduced for wide bandwidth envelope which is the main consideration of this architecture. The optimization of the second architecture for wider bandwidth envelope is presented including the output filter design, switching frequency and the number of phases. The filter design area is restrained by fast transition and the minimum pulse of hardware. The fast transition needs small filter but the minimum pulse of hardware limitation pushes the filter in opposite way. The converter switching frequency mainly affects the minimum pulse limitation and the power loss. With lower switching frequency, the pulse width in the transition is smaller. The number of phases related to specific application can be optimized in terms of overall efficiency. Another aspect of optimization is improving control strategy. Transition shift allows tracking some parts of envelope that are faster than the hardware can support at the price of complexity. The new transition synchronization method increases the frequency of transition, allowing the multilevel voltage to be closer to the envelope. Both control strategies push the converter to track wider bandwidth envelope than the limitation of power stage. The power loss model of envelope amplifier is detailed and validated by measurements. The power loss mechanism of buck converter has to include the transitions in real time operation, which is different from classical power loss model of synchronous buck converter. This model estimates the system efficiency and play a very important role in optimization process. Finally, the second envelope amplifier architecture is integrated with a Class F amplifier. EER system measurement proves the power saving with the proposed envelope amplifier without disrupting the linearity performance.

Trade-off study on deorbiting S/C in near polar orbit

Usual long, flexible, ED tethers kept vertical by the gravity gradient might be less efficient for deorbiting S/C in near-polar orbits than conventional (Hall, Ion) electrical thrusters. A trade-off study on this application is here presented for tethers kept horizontal and perpendicular to the orbital plane. A tether thus oriented must be rigid and short for structural reasons, requiring a non-convex cross section and a power supply as in the case of electrical thrusters. Very recent developments on bare-tether collection theory allow predicting the current collected by an arbitrary cross section. For the horizontal tether, structural considerations on length play the role of ohmic effects in vertical tethers, in determining the optimal contribution of tether mass to the overall deorbiting system. For a given deorbiting-mission impulse, tether-system mass is minimal at some optimal length that increases weakly with the impulse. The horizontal-tether system may beat both the vertical tether and the electrical thruster as regards mass requirements for a narrow length range centered at about 100 m, allowing, however, for a broad mission-impulse range.

Interregional trade changes in Spain caused by the introduction of a road fee charge for heavy goods vehicles

The introduction of a homogeneous road charging system according to the Directive 2011/76/EU for the use of roads is still under development in most European Union (EU) member states. Spain, like other EU members, has been encouraged to introduce a charging system for Heavy Goods Vehicles (HGVs) throughout the country. This nationwide charge has been postponed because there are serious concerns about their advantages from an economic point of view. Within this context, this paper applies an integrated modeling approach to shape elastic trade coefficients among regions by using a random utility based multiregional Input- Output (RUBMRIO) approach and a road transport network model in order to determine regional distributive and substitutive economic effects by simulating the introduction of a distance-based charge (?/km) considering 7,053.8 kilometers of free highways linking the capitals of the Spanish regions. In addition, an in-depth analysis of interregional trade changes is developed to evaluate and characterize the role of the road charging approach in trade relations among regions and across freight intensive economic sectors. For this purpose, differences in trade relations are described and assessed between a base-case or ?do nothing? scenario and a road fee-charge setting scenario. The results show that the specific amount of the charge set for HGVs affect each region differently and to a different extent because in some regions the price of commodities and the Generalized Transport Cost will decrease its competiveness within the country.

Economic Partnership Agreements in the EU's post-Lome trade regime: negotiations with West Africa. ZEI Discussion Paper C214, 2012

Trade is a key element of the development policy of the European Union (EU). As the most important trading partner of developing countries, the EU attempts to facilitate the participation of developing countries in global trade and contribute to economic growth through providing market access and financial assistance. For twenty-five years, the commitment of the EU was largely focused on its former colonies, more specifically in Africa, the Caribbean and the Pacific (ACP). The developing world, in terms of the EU’s trade policy, was therefore divided between ACP states with special provisions under the Lomé Conventions and all other developing countries. With the new millennium, this special relationship came to an end. Pressure from several member states1 and the World Trade Organization (WTO) led to an overhaul of the EU’s trade regime vis-à-vis developing countries and to the loss of the privileged position of ACP countries. The result of this overhaul is still pending. Economic Partnership Agreements (EPAs) – to be negotiated between the EU and several ACP regions – have only been realized in the Caribbean. This article will to examine the negotiations between the EU and West Africa and discuss the interests involved on the African side. Following the introduction, the second part of this article is dedicated to the Lomé Conventions with a focus on the change occurring from the third to the fourth revision in order to understand the current situation. The third part is going to take a look at the Cotonou agreement and the trade regime of the EU in general before turning to the negotiations for an Economic Partnership Agreement between the EU and West Africa. The conclusion summarizes the main findings.

The EU and Brazil: Partnering in an uncertain world? CEPS Working Document No. 382, 13 May 2013

The international system is changing fast and both the European Union and Brazil will need to adapt. This paper argues that such a process of adjustment may bring the two closer together, even if their starting points differ considerably. Europe looks at the ongoing redistribution of power as a challenge, Brazil as an opportunity. Europe is coping with the detrimental impact of the economic crisis on its international profile; Brazil is enhancing its influence in its region and beyond. Their normative outlook is broadly compatible; their political priorities and behaviour in multilateral frameworks often differ, from trade to development and security issues. Despite the crisis, however, there are signals of renewed engagement by the EU on the international stage, with a focus on its troubled neighbourhood and partnerships with the US and large emerging actors such as Brazil. The latter is charting an original course in international affairs as a rising democratic power from the traditional South with no geopolitical opponents and a commitment to multilateralism. In testing the limits of its international influence, Brazil will need dependable partners and variable coalitions that go well beyond the BRICS format, which is not necessarily sustainable. This contribution suggests that the strategic partnership between the EU and Brazil may grow stronger not only as a platform to deepen economic ties and sustain growth, but also as a tool to foster cooperation in political and security affairs including crisis management, preventive diplomacy and human rights.

Innovative Capabilities and Market Performance: The European Union in International Comparison. Jean Monnet/Robert Schuman Paper Series Vol. 12, No. 7, September 2012

This paper investigates the EU’s international positioning in terms of innovative capabilities and global market performance by using most recent quantitative data on a wide branch of indicators. The EU’s performance is compared to the standings of its most important economic competitors and emerging economic powerhouses: the USA, Japan, China, Brazil, India, Russia and South Africa. By doing so, this paper offer insightful and deep information about the EU’s power to compete and rank in international economic affairs. It will be proofed that the European Union ranks in many of the indicators related to innovative capabilities in good position and the EU’s overall global market performance is excellent, whereas the BRICS are underachieving.

Concording EU trade and production data over time. National Bank of Belgium Working Paper No. 239, December 2012

This paper provides concordance procedures for product-level trade and production data in the EU and examines the implications of changing product classifications on measured product adding and dropping at Belgian firms. Using the algorithms developed by Pierce and Schott (2012a, 2012b), the paper develops concordance procedures that allow researchers to trace changes in coding systems over time and to translate product-level production and trade data into a common classification that is consistent both within a single year and over time. Separate procedures are created for the eightdigit Combined Nomenclature system used to classify international trade activities at the product level within the European Union as well as for the eight-digit Prodcom categories used to classify products in European domestic production data. The paper further highlights important differences in coverage between the Prodcom and Combined Nomenclature classifications which need to be taken into account when generating combined domestic production and international trade data at the product level. The use of consistent product codes over time results in less product adding and dropping at continuing firms in the Belgian export and production data.

The Judicial Dimension of the European Neighbourhood Policy. EU Diplomacy Paper 08/2013, November 2013

In this paper, the expression “neighbourhood policy” of the European Union (EU) is understood in a broad way which includes the members of the European Free Trade Association (EFTA) contracting parties to the European Economic Area (EEA), the EFTA State Switzerland, candidate states, the countries of the European Neighbour-hood Policy (ENP), and Russia. The European Court of Justice (ECJ) is the centre of gravity in the judicial dimension of this policy. The innermost circle of integration after the EU itself comprises the EFTA States who are party to the European Economic Area. With the EFTA Court, they have their own common court. The existence of two courts – the ECJ and the EFTA Court – raises the question of homogeneity of the case law. The EEA homogeneity rules resemble the ones of the Lugano Convention. The EFTA Court is basically obliged to follow or take into account relevant ECJ case law. But even if the ECJ has gone first, there may be constellations where the EFTA Court comes to the conclusion that it must go its own way. Such constellations may be given if there is new scientific evidence, if the ECJ has left certain questions open, where there is relevant case law of the European Court of Human Rights or where, in light of the specific circumstances of the case, there is room for “creative homogeneity”. However, in the majority of its cases the EFTA Court is faced with novel legal questions. In such cases, the ECJ, its Advocates General and the Court of First Instance make reference to the EFTA Court’s case law. The question may be posed whether the EEA could serve as a model for other regional associations. For the ENP states, candidate States and Russia this is hard to imagine. Their courts will to varying degrees look to the ECJ when giving interpretation to the relevant agreements. The Swiss Government is – at least for the time being – unwilling to make a second attempt to join the EEA. The European Commission has therefore proposed to the Swiss to dock their sectoral agreements with the EU to the institutions of the EFTA pillar, the EFTA Surveillance Authority (ESA) and the EFTA Court. Switzerland would then negotiate the right to nominate a member of the ESA College and of the EFTA Court. The Swiss Government has, however, opted for another model. Swiss courts would continue to look to the ECJ, as they did in the past, and conflicts should also in the future be resolved by diplomatic means. But the ECJ would play a decisive role in dispute settlement. It would, upon unilateral request of one side, give an “authoritative” interpretation of EU law as incorporated into the relevant bilateral agreement. In a “Non-Paper” which was drafted by the chief negotiators, the interpretations of the ECJ are even characterised as binding. The decision-making power would, however, remain with the Joint Committees where Switzerland could say no. The Swiss Government assumes that after a negative decision by the ECJ it would be able to negotiate a compromise solution with the Commission without the ECJ being able to express itself on the outcome. The Government has therefore not tried to emphasise that the ECJ would not be a foreign court. Whether the ECJ would accept its intended role, is an open question. And if it would, the Swiss Government would have to explain to its voters that Switzerland retains the freedom to disregard such a binding decision and that for this reason the ECJ is not only no foreign court, but no adjudicating court at all.

To Be or Not to Be a Normative Power: The EU’s Promotion of Human Rights and Democracy in Russia. Bruges Regional Integration & Global Governance Papers 2/2013

The ‘Normative Power Europe’ debate has been a leitmotif in the academic discourse for over a decade. Far from being obsolete, the topic is as relevant as when the term was first coined by Ian Manners in 2002.1 ‘To be or not to be a normative power’ is certainly one of the existential dilemmas in the foreign policy of the European Union. This paper, however, intends to move beyond the black-and-white debate on whether the European Union is a normative power and to make it more nuanced by examining the factors that make it such. Contrary to the conventional perception that the European Union is a necessarily ‘benign’ force in the world, it assumes that it has aspirations to be a viable international actor. Consequently, it pursues different types of foreign policy behaviour with a varying degree of normativity in them. The paper addresses the question of under what conditions the European Union is a ‘normative power’. The findings of the study demonstrate that the ‘normative power’ of the European Union is conditioned upon internal and external elements, engaged in a complex interaction with a decisive role played by the often neglected external elements.

EU Trade Actors after Lisbon: Enhanced Negotiations or Business as Usual? Brugges Political Research Paper No. 32, November 2013

As seen by the launching of trade negotiations with Japan and the United States, the European Union has shifted gears in order to achieve amplified benefits in bilateral trade agreements. The entry into force of the Lisbon Treaty brought the European Parliament and the European External Action Service into the picture as new actors in trade negotiations. The question arises if the new framework of trade negotiations is better off than the pre-Lisbon era. By applying Veto Players theory to the Central American Association Agreement and Principal-Agent theory to the Ukrainian Association Agreement, two results were concluded. First, the participation of the European Parliament as a veto player has decreased the effectiveness of trade negotiation. Second, the participation of the European External Action Service has shown the contrary, namely an increase of effectiveness in trade negotiations.

Basic statistics of the Community. Comparison with some European countries, Canada, the United States of America and the Union of Soviet Socialist Republics 1965. Sixth edition

Population; labour force; national product; agriculture; energy; industry; transport; external trade; social statistics; standard of living; trends of major economic indicators in the countries of the Community; supplementary statistics on iron and steel-trends from 1959-64.

Trade policy issues in the Wider Europe – that led to war and not yet to peace. CEPS Working Document No. 398, July 2014

This paper looks at the trade policy landscape of the EU and the wider Europe, with a focus on issues arising from the signature on 27 June 2014 of Deep and Comprehensive Free Trade Agreements (DCFTAs) between the EU and three East European countries (Georgia, Moldova and Ukraine), and actual or prospective issues relating to the customs union of Belarus, Russia and Kazakhstan (BRK), and the Eurasian Economic Union whose founding treaty was signed on 29 May 2014. The huge expansion of intercontinental free trade area negotiations currently underway, in which the EU is an active participant alongside much of the Americas and Asia, stands in contrast with Russia’s choice to restrict itself to the Eurasian Economic Union, which is only a marginal extension of its own economy. Alone among the major economies in the world, Russia does not seek to integrate economically with any major economic bloc, which should be a matter of serious concern for Moscow. Within the wider Europe, the EU’s DCFTAs with Ukraine, Moldova and Georgia are a major new development, but Russia now threatens trade sanctions against Ukraine in particular, the economic case for which seems unfounded and whose unilateral application would also impair the customs union. The Belarus-Russia-Kazakhstan customs union itself poses several issues of compatibility with the rules of the WTO, which in turn are viewed by the EU as an impediment to discussing possible free trade scenarios with the customs union, although currently there are far more fundamental political impediments to any consideration of such ideas. Nonetheless, this paper looks at various long-term scenarios, if only as a reminder that there could be much better alternatives to the present context of conflict around Ukraine.

The Shaping of EU-Mercosur Relations: From Altruism to Pragmatism and Liberalism to Illiberalism. Pittsburgh Papers on the European Union Vol. 1, (2012)

Deeply-embedded norms of liberalism and protectionism alongside EU policies focusing on promoting development and regional integration have shaped EU-Mercosur relations. These stand in stark contrast to the policies of the US, the historic hegemon in the region. This paper utilizes historical institutionalism to understand how the liberal tenets of EU competition policy and the protectionism of Common Agricultural Policy (CAP) have affected EU-Mercosur relations. Particular foci include Spain’s role in spearheading efforts to promote EU-Latin American relations and the way EU competition policies directed against monopolies in Europe spurred increased investment in Latin America, especially the Southern Cone. The latter prompted the EU to forge closer ties with Mercosur, encouraged cooperation and development programs and spurred regional integration and liberal trade regimes in Latin America.

The Transatlantic Trade and Investment Partnership: A long hard road to multilateralism? EPC Commentary, 26 September 2014

The seventh round of the Transatlantic Trade and Investment Partnership (TTIP) negotiations between the European Union and the United States will take place in Washington on 29 September. If concluded successfully, the TTIP would become the world’s largest free trade pact. The EU and the US account for nearly half of the world’s GDP and 30% of world trade with exchanges of goods and services worth around €723 billion a year and €1.8 billion a day. The Partnership, unprecedented in its scope and ambition, has generated great expectations which will be hard to meet in reality. It could however have a beneficial effect on trade multilateralism, provided that it is the result of an open negotiating process.