Transfer signal without wire has been widely accepted after the introduction of cellular technology and WiFi technology, hence the power cable is the last wire that has yet to be eliminated. Inductive power transfer (IPT) has drawn substantial interest in both academia and industry due to its advantages including convenience, nonexistence of cable and connector, no electric shock issue, ability to work under some extreme environment, and so on. After performing thorough literature review of IPT systems, two major drawbacks including low power efficiency and coil displacement sensitivity are identified as the main obstacles that have to be solved in order for these systems to reach full functionality and compete with existing wired solutions. To address the limitations and design challenges in the IPT systems, a detailed electric circuit modeling of individual part of the IPT DC-DC stage is performed. Several resonant DC-AC inverters and output AC-DC rectifiers are compared based on their performance and feasibility in inductive charging applications. Different equivalent circuit models for the loosely coupled transformer (LCT) are derived which allows for better understanding on how power is distributed among the circuit components. Five compensation networks to improve the power transfer efficiency are evaluated and their suitable application occasions are identified. With comprehensive circuit model analysis, the influence of the resonant compensation tank parameters has been investigated carefully for efficient power transfer. A novel tuning network parameters design methodology is proposed based on multiple given requirement such as battery charging profile, geometry constraints and operating frequency range, with the aim of avoiding bifurcation phenomenon during the whole charging process and achieving decent efficiency. A 4-kW hardware prototype based on the proposed design approach is built and tested under different gap and load conditions. Peak IPT system DC-DC efficiencies of 98% and 96.6% are achieved with 4-cm and 8-cm air gap conditions, which is comparable to the conventional plug-in type or wired charging systems for EVs. A long-hour test with real EV batteries is conducted to verify the wireless signal transmission and CC/CV mode seamless transition during the whole charging profile without bifurcation. To reduce the IPT system sensitivity to the gap variation or misalignment, a novel LCT design approach without additional complexity for the system is proposed. With the aid of FEA simulation software, the influence of coil relative position and geometry parameters on the flux distribution and coupling coefficient of the transmitter and receiver is studied from an electromagnetic perspective. An asymmetrical LCT based on the proposed design method is built to compare with a traditional symmetrical LCT. With fixed 10-mm gap and 0 to 40-mm misalignment variation, the coupling coefficient for the symmetrical LCT drops from 0.354 to 0.107, and the corresponding efficiency decrease is 16.6%. The operating frequency variation is nearly 100 kHz to maintain same input/output condition. When employing the proposed asymmetrical LCT, the coupling coefficient changes between 0.312 and 0.273, and the maximum efficiency deviation is kept within 0.67% over the entire 40-mm misalignment range. Moreover, the required frequency range to achieve same operation condition is less than 10 kHz. Lastly, some design considerations to further improve the IPT system efficiency are proposed on the basis of the designed asymmetrical LCT geometry. For given circuit specifications and LCT coupling conditions, determination of the optimal primary winding turns number could help achieve minimal winding loss and core loss. For lower output power, the optimal primary winding turns number tends to be larger compared to that for higher output power IPT system. Two asymmetrical LCT with similar dimension but different number of turns are built and tested with a 100-W hardware prototype for laptop inductive charging. The proposed efficiency improvement methodology is validated by the winding loss and core loss from experimental results. / Ph. D.

One of the main tasks of key account management (KAM) practice is the creation of customized value propositions for a business-to-business organization's most important customers, which often requires the support of multiple internal departments. Thus, making internal alignment central in KAM in order to exchange value and serve the key accounts (KA) long-term. This study will, therefore, explore internal alignment in KAM and aims to identify what contributes to internal alignment and how misalignment could emerge in KAM teams, in order to understand the significance of internal alignment and identify possible reasons for misalignment in KAM. The theory was framed by 7 elements of internal alignment including shared values, style, skills, staff, strategy, structure and systems. The empirical data was collected through qualitative semi-structured interviews with KA managers. The findings suggest that internal alignment is of importance in KAM and that the elements of internal alignment studied in the thesis are dependent on each other. Furthermore, it was found that misalignment is most commonly caused by personal disputes, however, all elements studied were found as contributing factors to misalignment. The findings led to the conclusion that internal alignment is not a target state, it is rather a measure of progress and that all aspects that do contribute to internal alignment also entail causes for misalignment.

A transferência de energia sem fio (WPT) rege um importante papel no carregamento de aparelhos remotos. Em um acoplamento indutivo ressonante há várias topologias de sistemas WPT que podem ser implementados para realizar a transferência de energia. Neste trabalho é utilizado uma topologia que utiliza quatro capacitores de compensação para realizar o ajuste da potência entregue a carga, onde estes capacitores são calculados através das fixações dos demais parâmetros do circuito elétrico. Quando o sistema WPT é projetado, uma distância fixa entre as bobinas é almejada, todavia há incertezas e movimentos que podem provocar a alteração desta distância. Há várias técnicas na literatura que buscam realizar a sintonia do acoplamento indutivo para compensar estes desalinhamentos gerado entre as bobinas. Este trabalho apresenta um método multivariável para maximização da potência entregue a carga em um sistema de transferência sem fio. O método proposto utiliza os conceitos de um capacitor variável e a variação de frequência a fim de variar a potência entregue a carga. Os resultados experimentais obtidos para os fatores de acoplamento magnético k > 0;3 mostraram que controlando a frequência e uma capacitância da rede de compensação o desempenho do sistema é melhor que os casos onde apenas uma dessas variáveis é controlada. / Wireless power transfer (WPT) plays an important rule in charging remote devices. In a resonant inductive coupling there are several topologies of WPT systems that can be implemented to perform the energy transfer. In this work, a topology is used that uses four capacitors of compensation to realize the adjustment of the power delivered to load, where these capacitors are calculated through the xations of the other parameters of the electric circuit. When the WPT system is designed, a xed distance between coils is desired, however there are uncertainties and movements that may cause this distance to change. There are several techniques in the literature that seek to realize the tuning of the inductive coupling to compensate for these misalignments generated between the coils. This work presents a multivariable method to maximize the power delivered to the load in a wireless transfer system. The proposed method uses the concepts of a variable capacitor and the frequency variation in order to vary the power delivered to the load. The experimental results obtained for the magnetic coupling factors k > 0:3 showed that controlling the frequency and capacitance of the compensation network system performance is better than the cases where only one of these variables is controlled.

Wireless power transfer (WPT) technologies have become important for our everyday life. The most commonly used near-field WPT method is inductive coupling, which suffers from low efficiency and small range. The Strongly Coupled Magnetic Resonance (SCMR) method was developed recently, and it can be used to wirelessly transfer power with higher efficiency over a longer distance than the inductive coupling method. This dissertation develops new SCMR systems that have better performance compared to standard SCMR systems. Specifically, two new 3-D SCMR systems are designed to improve the angular misalignment sensitivity of WPT systems. Their power transfer efficiency for different angular misalignment positions are studied and analyzed. Prototypes are built for both systems and their performance is validated through measurement. Furthermore, new planar broadband conformal SCMR (CSCMR) systems are developed that maintain high efficiency while providing significantly larger bandwidth than standard CSCMR systems. Such broadband CSCMR systems are used here for the first time to simultaneously accomplish highly efficient wireless power transfer and high data rate communication through the same wireless link. These systems that combine wireless power and communication are expected to enable next-generation applications with battery-less and “power-hungry” sensors. Example applications include implantable and wearable sensors as well as embedded sensors for structural health monitoring.

The growth performance of the South African economy over the past two and a half decades has been disappointing. The economy has not reached the high growth rates of the 1960s, which is desperately needed to alleviate poverty in the country. While the sources of growth have been a subject of much debate, recently the notion that the Real Exchange Rate (RER) level of a country matters for growth has attracted attention. While it is generally expected that the value of the currency should not remain constant and that the exchange rate fluctuates over time, in the long-term, it is expected to converge to an equilibrium level South Africa follows an inflation targeting framework and a free floating exchange rate regime. The exchange rate has been highly volatile since the abolishment of the dual exchange rate system in 1995. This implies that there were periods of overvaluation and undervaluation from the equilibrium level; in other words the rand experienced times of misalignment. In the event of misalignments, the RER is moved to levels which make it difficult for an economy to sustain international competitiveness over the long-run, and this is harmful to growth rates in the economy. This is especially true for countries, such as South Africa, which is heavily dependent on exports. The RER is therefore very powerful and has been argued to be the cause of loss of competitiveness and growth slowdowns. This study investigates this notion for South Africa. The main aim of this study is therefore to investigate the effects of RER misalignment on economic growth in South Africa. This implies that the study aims to determine the level of RER equilibrium, the misalignment in the real value of the rand, and how this misalignment has affected economic growth in the country. The Behavioural Equilibrium Exchange Rate (BEER) approach is followed to determine the Equilibrium Exchange Rate (EER), which allows for the use of fundamental macroeconomic variables to determine the real equilibrium level of the rand. Identified fundamental variables, which are the main drivers of the current RER in South Africa, include GDP per capita, trade openness, terms of trade, gross fixed capital formation and the real interest rate differential. A Vector Error-Correction Mechanism (VECM) is used in the estimation of the Real Equilibrium Exchange Rate (REER). Misalignment is calculated as the difference between the actual and the equilibrium real exchange rate. It is found that during the period under investigation (1985 to 2011) there have been substantial misalignments in the RER of the rand, though the currency was mostly overvalued. It is also shown that the rand does revert to its equilibrium level over time. The least square method is used to determine the effect of this RER misalignment on economic growth. Additional variables such as the initial level of GDP per capita, trade openness, terms of trade as well as gross fixed capital formation, are included in the growth specification. Trade reforms emphasise the importance of export-led growth in a commodity-rich economy, such as South Africa. The results indicate that the RER misalignment has a positive coefficient; this implies that a misalignment in the rand has not necessarily been harmful to economic growth. Therefore, it can be concluded that in the case of South Africa, misalignment is generally stimulating growth, but more so when the currency is undervalued. The results therefore show that the RER should be kept at competitive levels in order to boost economic growth in the country. The results also show support for the strategy of export-led growth in South Africa. / Thesis (MCom (Economics))--North-West University, Potchefstroom Campus, 2013.

The growth performance of the South African economy over the past two and a half decades has been disappointing. The economy has not reached the high growth rates of the 1960s, which is desperately needed to alleviate poverty in the country. While the sources of growth have been a subject of much debate, recently the notion that the Real Exchange Rate (RER) level of a country matters for growth has attracted attention. While it is generally expected that the value of the currency should not remain constant and that the exchange rate fluctuates over time, in the long-term, it is expected to converge to an equilibrium level South Africa follows an inflation targeting framework and a free floating exchange rate regime. The exchange rate has been highly volatile since the abolishment of the dual exchange rate system in 1995. This implies that there were periods of overvaluation and undervaluation from the equilibrium level; in other words the rand experienced times of misalignment. In the event of misalignments, the RER is moved to levels which make it difficult for an economy to sustain international competitiveness over the long-run, and this is harmful to growth rates in the economy. This is especially true for countries, such as South Africa, which is heavily dependent on exports. The RER is therefore very powerful and has been argued to be the cause of loss of competitiveness and growth slowdowns. This study investigates this notion for South Africa. The main aim of this study is therefore to investigate the effects of RER misalignment on economic growth in South Africa. This implies that the study aims to determine the level of RER equilibrium, the misalignment in the real value of the rand, and how this misalignment has affected economic growth in the country. The Behavioural Equilibrium Exchange Rate (BEER) approach is followed to determine the Equilibrium Exchange Rate (EER), which allows for the use of fundamental macroeconomic variables to determine the real equilibrium level of the rand. Identified fundamental variables, which are the main drivers of the current RER in South Africa, include GDP per capita, trade openness, terms of trade, gross fixed capital formation and the real interest rate differential. A Vector Error-Correction Mechanism (VECM) is used in the estimation of the Real Equilibrium Exchange Rate (REER). Misalignment is calculated as the difference between the actual and the equilibrium real exchange rate. It is found that during the period under investigation (1985 to 2011) there have been substantial misalignments in the RER of the rand, though the currency was mostly overvalued. It is also shown that the rand does revert to its equilibrium level over time. The least square method is used to determine the effect of this RER misalignment on economic growth. Additional variables such as the initial level of GDP per capita, trade openness, terms of trade as well as gross fixed capital formation, are included in the growth specification. Trade reforms emphasise the importance of export-led growth in a commodity-rich economy, such as South Africa. The results indicate that the RER misalignment has a positive coefficient; this implies that a misalignment in the rand has not necessarily been harmful to economic growth. Therefore, it can be concluded that in the case of South Africa, misalignment is generally stimulating growth, but more so when the currency is undervalued. The results therefore show that the RER should be kept at competitive levels in order to boost economic growth in the country. The results also show support for the strategy of export-led growth in South Africa. / Thesis (MCom (Economics))--North-West University, Potchefstroom Campus, 2013.

A transferência de energia sem fio (WPT) rege um importante papel no carregamento de aparelhos remotos. Em um acoplamento indutivo ressonante há várias topologias de sistemas WPT que podem ser implementados para realizar a transferência de energia. Neste trabalho é utilizado uma topologia que utiliza quatro capacitores de compensação para realizar o ajuste da potência entregue a carga, onde estes capacitores são calculados através das fixações dos demais parâmetros do circuito elétrico. Quando o sistema WPT é projetado, uma distância fixa entre as bobinas é almejada, todavia há incertezas e movimentos que podem provocar a alteração desta distância. Há várias técnicas na literatura que buscam realizar a sintonia do acoplamento indutivo para compensar estes desalinhamentos gerado entre as bobinas. Este trabalho apresenta um método multivariável para maximização da potência entregue a carga em um sistema de transferência sem fio. O método proposto utiliza os conceitos de um capacitor variável e a variação de frequência a fim de variar a potência entregue a carga. Os resultados experimentais obtidos para os fatores de acoplamento magnético k > 0;3 mostraram que controlando a frequência e uma capacitância da rede de compensação o desempenho do sistema é melhor que os casos onde apenas uma dessas variáveis é controlada. / Wireless power transfer (WPT) plays an important rule in charging remote devices. In a resonant inductive coupling there are several topologies of WPT systems that can be implemented to perform the energy transfer. In this work, a topology is used that uses four capacitors of compensation to realize the adjustment of the power delivered to load, where these capacitors are calculated through the xations of the other parameters of the electric circuit. When the WPT system is designed, a xed distance between coils is desired, however there are uncertainties and movements that may cause this distance to change. There are several techniques in the literature that seek to realize the tuning of the inductive coupling to compensate for these misalignments generated between the coils. This work presents a multivariable method to maximize the power delivered to the load in a wireless transfer system. The proposed method uses the concepts of a variable capacitor and the frequency variation in order to vary the power delivered to the load. The experimental results obtained for the magnetic coupling factors k > 0:3 showed that controlling the frequency and capacitance of the compensation network system performance is better than the cases where only one of these variables is controlled.

A transferência de energia sem fio (WPT) rege um importante papel no carregamento de aparelhos remotos. Em um acoplamento indutivo ressonante há várias topologias de sistemas WPT que podem ser implementados para realizar a transferência de energia. Neste trabalho é utilizado uma topologia que utiliza quatro capacitores de compensação para realizar o ajuste da potência entregue a carga, onde estes capacitores são calculados através das fixações dos demais parâmetros do circuito elétrico. Quando o sistema WPT é projetado, uma distância fixa entre as bobinas é almejada, todavia há incertezas e movimentos que podem provocar a alteração desta distância. Há várias técnicas na literatura que buscam realizar a sintonia do acoplamento indutivo para compensar estes desalinhamentos gerado entre as bobinas. Este trabalho apresenta um método multivariável para maximização da potência entregue a carga em um sistema de transferência sem fio. O método proposto utiliza os conceitos de um capacitor variável e a variação de frequência a fim de variar a potência entregue a carga. Os resultados experimentais obtidos para os fatores de acoplamento magnético k > 0;3 mostraram que controlando a frequência e uma capacitância da rede de compensação o desempenho do sistema é melhor que os casos onde apenas uma dessas variáveis é controlada. / Wireless power transfer (WPT) plays an important rule in charging remote devices. In a resonant inductive coupling there are several topologies of WPT systems that can be implemented to perform the energy transfer. In this work, a topology is used that uses four capacitors of compensation to realize the adjustment of the power delivered to load, where these capacitors are calculated through the xations of the other parameters of the electric circuit. When the WPT system is designed, a xed distance between coils is desired, however there are uncertainties and movements that may cause this distance to change. There are several techniques in the literature that seek to realize the tuning of the inductive coupling to compensate for these misalignments generated between the coils. This work presents a multivariable method to maximize the power delivered to the load in a wireless transfer system. The proposed method uses the concepts of a variable capacitor and the frequency variation in order to vary the power delivered to the load. The experimental results obtained for the magnetic coupling factors k > 0:3 showed that controlling the frequency and capacitance of the compensation network system performance is better than the cases where only one of these variables is controlled.

Submitted by Pierre Marinho (pierre.marinho@uol.com.br) on 2013-03-08T15:52:05Z No. of bitstreams: 1 MPFE_Dissertacao_Pierre da Silva Marinho_VF.pdf: 205056 bytes, checksum: f7e17dd57f3b948dffa3140396cbbb86 (MD5) / Approved for entry into archive by Suzinei Teles Garcia Garcia (suzinei.garcia@fgv.br) on 2013-03-08T15:55:29Z (GMT) No. of bitstreams: 1 MPFE_Dissertacao_Pierre da Silva Marinho_VF.pdf: 205056 bytes, checksum: f7e17dd57f3b948dffa3140396cbbb86 (MD5) / Made available in DSpace on 2013-03-08T15:57:28Z (GMT). No. of bitstreams: 1 MPFE_Dissertacao_Pierre da Silva Marinho_VF.pdf: 205056 bytes, checksum: f7e17dd57f3b948dffa3140396cbbb86 (MD5) Previous issue date: 2013-02-05 / The objective of this paper is to analyze the evidences of long-run relationship among three variables: real exchange rate ('RER'), international investment position ('NFA') and the Balassa-Samuelson effect ('PREL') in a group of 28 countries. This group is composed of countries in different stages of economic development. The methodology utilized to assess long-run relationship was cointegration. The tests performed were developed by Bierens (1997), nonparametric test, and by Saikkonen and Lütkepohl (2000a, b, c), test that firstly estimates a deterministic term. Evidences of cointegration were found in both tests for the majority of the countries. However, there were significant differences between the results of the two performed tests. These differences between the two results and also some special cases of countries that did not demonstrated evidences of cointegration require deeper studies on the long-run behavior of the three variables analyzed in this paper. / Este trabalho tem a finalidade de analisar as evidências de relações de longo prazo entre a taxa de câmbio real ('RER'), a posição internacional de investimentos ('NFA') e o efeito Balassa-Samuelson ('PREL') em um grupo de 28 países, grupo este que inclui países em diferentes estágios de desenvolvimento. A metodologia utilizada foi a de testes de cointegração. Os testes aplicados foram desenvolvidos por Bierens (1997), teste não paramétrico, e por Saikkonen e Lütkepohl (2000a, b, c), teste que consiste em primeiro estimar um termo determinístico. Evidências de cointegração são constatadas, em ambos os testes, na maioria dos países estudados. Entretanto, houve diferenças relevantes entre os resultados encontrados através dos dois testes aplicados. Estas diferenças entre os resultados, bem como alguns casos especiais de países que não demonstraram evidências de cointegração, requerem análises mais aprofundadas sobre o comportamento de longo prazo das três variáveis estudadas.

A wide range of non-destructive testing (NDT) methods for the monitoring the health of concrete structure has been studied for several years. The recent rapid evolution of wireless sensor network (WSN) technologies has resulted in the development of sensing elements that can be embedded in concrete, to monitor the health of infrastructure, collect and report valuable related data. The monitoring system can potentially decrease the high installation time and reduce maintenance cost associated with wired monitoring systems. The monitoring sensors need to operate for a long period of time, but sensors batteries have a finite life span. Hence, novel wireless powering methods must be devised. The optimization of wireless power transfer via Strongly Coupled Magnetic Resonance (SCMR) to sensors embedded in concrete is studied here. First, we analytically derive the optimal geometric parameters for transmission of power in the air. This specifically leads to the identification of the local and global optimization parameters and conditions, it was validated through electromagnetic simulations. Second, the optimum conditions were employed in the model for propagation of energy through plain and reinforced concrete at different humidity conditions, and frequencies with extended Debye's model. This analysis leads to the conclusion that SCMR can be used to efficiently power sensors in plain and reinforced concrete at different humidity levels and depth, also validated through electromagnetic simulations. The optimization of wireless power transmission via SMCR to Wearable and Implantable Medical Device (WIMD) are also explored. The optimum conditions from the analytics were used in the model for propagation of energy through different human tissues. This analysis shows that SCMR can be used to efficiently transfer power to sensors in human tissue without overheating through electromagnetic simulations, as excessive power might result in overheating of the tissue. Standard SCMR is sensitive to misalignment; both 2-loops and 3-loops SCMR with misalignment-insensitive performances are presented. The power transfer efficiencies above 50% was achieved over the complete misalignment range of 0°-90° and dramatically better than typical SCMR with efficiencies less than 10% in extreme misalignment topologies.