SELECTING THE TIME OF CONCENTRATION CONSIDERING GROUNDWATER DEPTH AND RUNOFF COEFFICIENT IN THE ARGENTINIAN PAMPA REGION: Seleção do tempo de concentração considerando profundidade das águas subterrâneas e coeficiente de escoamento na região do pampa argentino

The time of concentration (Tc) is one of the most sensitive parameters for calculating the maximum runoff in a basin and plays a key role in the determination of design flows. In this work, the consistency of the equations that make up the analytical methods used to estimate the Tc is evaluated through the contrast of observed events from the application of the graphical method in a plain basin located in the Pampa region, Argentina. The methodology used considers the complexity of the runoff generation process and of the water dynamics of the region taking into account the analysis of the groundwater depth and the runoff coefficient. This study shows that the equations available may generate Tc predictions with errors by up to 95% in plain basins. The results indicated that Ventura’s and Pasini’s equations are suitable to determine Tc under water deficit, while Izzard’s and Kinematic Wave equations are appropriate for saturated conditions of the system.El tiempo de concentración (Tc) es uno de los parámetros más sensibles para calcular el escurrimiento máximo en una cuenca y juega un papel fundamental en la determinación de los caudales de diseño. En este trabajo se evalúa la consistencia de las ecuaciones que componen los métodos analíticos utilizados para estimar el Tc mediante el contraste de eventos observados a partir de la aplicación del método gráfico en una cuenca de llanura ubicada en la región Pampeana, Argentina. La metodología utilizada considera la complejidad del proceso de generación de escorrentía y la dinámica hídrica de la región teniendo en cuenta el análisis de la profundidad del agua subterránea y el coeficiente de escorrentía. Este estudio muestra que las ecuaciones disponibles pueden generar predicciones de Tc con errores de hasta un 95% en cuencas de llanura. Los resultados indicaron que las ecuaciones de Ventura y Pasini son adecuadas para determinar el Tc bajo condiciones de déficit hídrico, mientras que las ecuaciones de Izzard y Onda Cinemática son adecuadas para condiciones de saturación del sistema

비교우위의 동태적 변화와 경제성장 간의 관계에 대한 실증분석 연구

학위논문(박사) -- 서울대학교대학원 : 사회과학대학 경제학부, 2023. 2. 이근.본 논문은 경제성장과 동태적 비교우위 변화 간의 관계를 분석하는 데 목적이 있다. 경제성장 전략의 일환으로 수출 다변화와 수출 특화의 경제적 효과에 대한 논의가 지속되는 가운데 본 연구는 장기적인 경제성장을 위한 수출전략을 모색해 보고자 하는 관점에서 출발하였다. 본 연구는 개도국의 성공적인 경제발전 모델로 거론되는 한국과 대만의 변화하는 수출특화 패턴에 주목하였다. 한국과 대만의 수출은 지속적으로 소수의 상위 수출품에 집중되어 있는 한편 상위 수출품이 크게 변화한 특징을 보였다. 또한 변화하는 상위 수출품 구성은 자원 및 노동집약산업 중심에서 자본집약산업 중심으로 산업적 도약을 한 것으로 관측되었다. 한국과 대만의 공통된 수출 특화의 동태적 변화 현상은 비교우위 변화가 경제성장의 주요한 결정요인임을 주장한 이론연구와 맥락을 같이 한다. 동아시아 주요국의 수출패턴과 동태적 비교우위 변화에 대한 이론연구를 기반으로 본 연구는 비교우위의 동태적 변화가 경제성장에 미치는 장기적인 효과를 분석한다. 분석에는 내생성을 통제한 횡단면 동태적 패널분석 방법론인 시스템 GMM 추정과 함께 변수들 간 피드백 관계를 고려함으로써 내생성을 통제하며 설명변수의 장기적 효과를 분석하는 시계열 패널분석 방법론의 하나인 CS-DL (cross-sectionally augmented distributed lag) 추정을 경제성장 모형에 적용하였다. 논문의 핵심기여는 다음과 같다. 첫째, 새로운 상위 수출품 창출로 비교우위 변화를 사후적으로 추정하는 인덱스를 제시하고 비교우위 변화가 장기적인 경제효과가 있음을 실증적으로 보였다. 이러한 분석결과는 경제복잡성지수 (economic complexity index: ECI)를 포함한 추가적인 통제에도 일관되게 나타난 한편, ECI는 CS-DL 모형에서는 통계적 유의성이 없는 것으로 나타났다. 이러한 분석결과는 국가별 특성에 대한 고려 없이 선진국의 특화패턴을 지향하는 것이 비선진국의 장기적인 경제성장을 보장하지 않는다는 함의를 지닌다. 둘째, 비교우위 변화 인덱스를 통해 수출특화와 다변화는 상반된 개념이 아닌 상호 연관된 개념임을 보였다. 이는 일반적으로 새로운 특화 창출이 수출 다변화로 이어진다는 데에 기인한다. 셋째, 비선진국을 대상으로 기술수준별 비교우위 변화의 장기적인 경제효과를 분석한 결과 고기술 기반 비교우위 변화, 저기술 지반 비교우위 변화의 경제적 효과는 각각 유의하지 않은 것으로 나타났다. 이는 고기술 기반 비교우위 변화, 즉 선진국의 특화구조가 경제적 효과가 있음을 보인 선행연구와 대조되는 결과이다. 한편 비선진국을 대상으로 한 CS-DL 분석결과 1992년을 기점으로 기술증진을 동반한 비교우위 변화는 장기적인 경제효과가 있는 것으로 나타났다. 이는 단기적으로 현 시점의 비교우위 구조를 받아들이되 장기적 관점에서 비교우위 산업의 기술적 증진을 도모하는 점진적인 전략이 비선진국에게 유용한 성장전략이 될 수 있음을 시사한다.This thesis measures the dynamic comparative advantage (DCA) and empirically analyzes its effects on economic growth in the long run. In the context of economic development, determining a better trade strategy between diversification and specialization has been a topic of interest. Literature on export diversification highlights the growth effects of the overall degree of specialization, while literature on export specialization points out the importance of the quality of the specialization pattern. The successful export-led development experiences in East Asia—Korea and Taiwan—share some common features of export patterns. First, exports are concentrated on a relatively few top export products over the course of time. Second, the composition of top exports continuously changes. Third, change in the composition of top exports is associated with technological upgrading from low-to high-technological sectors. Theoretical literature on DCA and growth are in line with the shift in export specialization patterns of East Asia which highlight the role of DCA on long-run economic growth. This finding suggests that the emergence of new top exports which reflect a shift in comparative advantage can be an important source of drivers for sustainable growth. One of the main contributions of the study is the new measurement which captures the dynamic properties of comparative advantage. This study proposes that the emergence of new top exports captures the generation of new comparative advantage based on traditional trade theories arguing that under an opened economy, countries specialize in and trade products on the bases of their own comparative advantage. Two econometric techniques are applied to empirically investigate the effects of DCA on economic growth: the cross-sectional dynamic panel model (e.g., fixed effect and system GMM approach) and the cross-sectionally augmented distributed lag (CS-DL) approach. In particular, the CS-DL approach directly estimates the long-run effects in large dynamic heterogeneous time series panel model with cross-sectionally dependent errors (Chudik et al., 2016). Growth regressions consistently confirm the significant and positive impacts of change in comparative advantage on economic growth. The results are robust to a wide range of control variables, including the economic complexity index (ECI); whereas the ECI loses significance in the CS-DL estimations. Confirming the significant growth effects of the DCA, the second major contribution of this paper is related to an important feature of the DCA index. Given that the emergence of new export specialization leads to export diversification, the DCA index generally represents both aspects of export diversification and export specialization. This finding shows that export diversification and specialization are not opposite concepts but are actually related as pointed out by Nomaler and Verspagen (2021). Finally, another contribution relies on verifying the effects of the level of technology embedded in the new comparative advantage of growth in the long run. This thesis closely examines the DCA index through the lenses of the OECD industrial classification on technological intensity. Contrary to the findings of the literature on specialization which advocates the growth effects of specialization patterns with higher productivity (e.g., Lee, 2010), evidence is insufficient to support that new comparative advantage in higher or lower technological sectors over the course of time enhances per capita income in the long run. The CS-DL estimation results indicate that for non-developed economies, a gradual approach on creating new comparative advantage in higher technological sectors in the long run can be a viable alternative development strategy.Chapter 1. Introduction 1 Chapter 2. Literature on diversification, specialization, DCA, and economic growth 6 2.1. Export Diversification and economic growth 6 2.2. Export Specialization and economic growth 9 2.3. Theoretical framework for the research: DCA 12 2.4. Derivation of research hypothesis 15 Chapter 3. Econometric methods 21 3.1. Generalized method of moments approach 21 3.2. Cross-sectionally augmented distributed lag approach 23 Chapter 4. Growth effect of DCA 28 4.1. Introduction 28 4.2. Measuring changes in comparative advantage 28 4.3. Models and key variables 33 4.4. Empirical results: from DCA to economic growth 36 4.5. Concluding remarks and limitations of the study 50 Chapter 5. Growth effect of DCA tracking technological contents 52 5.1. Introduction 52 5.2. Generating a DCA index considering technological heterogeneity 54 5.3. Empirical results: from DCA, industrial upgrading, to economic growth 61 5.4. Concluding remarks 69 Chapter 6. Conclusion 71 Appendices 75 Bibliography 94 Abstract in Korean 100박

Directional Antenna System-Based DoA/RSS Estimation, Localization and Tracking in Future Wireless Networks: Algorithms and Performance Analysis

Location information plays an important role in many emerging technologies such as robotics, autonomous vehicles, and augmented reality. Already now the majority of smartphone owners use their devices' localization capabilities for a broad range of location-based services. Currently, location information in smartphones is mostly obtained in a device-centric approach, where the device to be localized, here referred to as the target node (TN), estimates its own location using, for example, the global positioning system (GPS). However, TNs with wireless communication capabilities can be localized based on their transmitted signals by a third party. In particular, localization can be implemented as a functionality of a wireless network. Depending on the application area and implementation, this network-centric approach has several advantages compared to device-centric localization, such as reducing the energy consumption within the TNs, enabling localization of non-cooperative TNs, and making location information available in the network itself. Current generation wireless networks are already capable of coarse localization. However, these existing localization capabilities do not suffice for the challenging demands of future applications. The majority of approaches moreover does not exploit the fact that an increasing number of base stations (BSs) and user devices are equipped with directional antennas. However, directional antennas enable direction of arrival (DoA) estimation that can, in turn, serve as the basis for advanced localization and location tracking. In this thesis, we thus study the application of directional antennas for localization and location tracking in future generation wireless networks. The contributions of this thesis can be grouped into two topics.First, this thesis provides a detailed study of DoA/received signal strength (RSS) estimation and localization with a group of directional antennas herein denoted as sectorized antennas. This group of antennas is of particular interest as it encompasses a broad range of directional antennas that can be implemented with a single RF front-end. Thus, the hardware complexity of sectorized antennas is low in comparison to the conventionally used antenna arrays that require multiple transceiver branches. However, at the same time this means that DoA estimation with sectorized antennas has to be implemented in a fundamentally different way. In order to address these differences, the study of sectorized antennas in this thesis includes the derivation of Cramer-Rao bounds (CRBs) for DoA/RSS estimation and localization, the proposal of three different DoA/RSS estimators, as well as numerical and analytical performance evaluations of DoA/RSS estimation and localization using sectorized antennas.Second, this thesis deals with localization based on the fusion of DoA and RSS estimates as well as DoA and time of arrival (ToA) estimates. It is shown that the combination of these estimates can result in a much increased localization performance compared to a localization based on one of these estimates alone. For the localization based on DoA/RSS estimates, a mechanism explaining this improvement is revealed by means of a CRB analysis. Thereafter, DoA/RSS-based fusion is further studied using an extended Kalman filter (EKF) as an example location tracking algorithm. Finally, an EKF is proposed that tracks the location of a TN by fusing DoA and ToA estimates. Apart from a significantly improved tracking performance, this joint DoA/ToA-EKF moreover provides estimates for the TN device clock offset and is able to localize the TN in situations where a classical DoA-only EKF fails to provide a location estimate altogether.Overall, this thesis thus provides insights into benefits of localization and location tracking using directional antennas, accompanied by specific DoA/RSS estimation, localization and location tracking solutions, as well as design guidelines for implementing localization systems in future generation wireless networks

Performance analysis of the interference adaptation dynamic channel allocation technique in wireless communication networks

Dynamic channel allocation (DCA) problem is one of the major research topics in the wireless networking area. The purpose of this technique is to relieve the contradiction between the increasing traffic load in wireless networks and the limited bandwidth resource across the air interface. The challenge of this problem comes from the following facts: a) even the basic DCA problem is shown to be NP-complete (none polynomial complete); b) the size of the state space of the problem is very large; and c) any practical DCA algorithm should run in real-time. Many heuristic DCA schemes have been proposed in the literature. It has been shown through simulation results that the interference adaptive dynamic channel allocation (IA-DCA) scheme is a promising strategy in Time Devision [sic] Multiple Accesss/Frequency Devision [sic] Multiple Accesss [sic] (TDMA/FDMA) based wireless communication systems. However, the analytical work on the IA-DCA strategy in the literature is nearly blank. The performance of a, DCA algorithm in TDMA/FDMA wireless systems is influenced by three factors: representation of the interference, traffic fluctuation, and the processing power of the algorithm. The major obstacle in analyzing IA-DCA is the computation of co-channel interference without the constraint of conventional channel reuse factors. To overcome this difficulty, one needs a representation pattern which can approximate the real interference distribution as accurately as desired, and is also computationally viable. For this purpose, a concept called channel reuse zone (CRZ) is introduced and the methodology of computing the area of a CRZ with an arbitrary, non-trivial channel reuse factor is defined. Based on this new concept, the computation of both downlink and uplink CO-channel interference is investigated with two different propagation models, namely a simplified deterministic model and a shadowing model. For the factor of the processing power, we proposed an idealized Interference Adaptation Maximum Packing (IAMP) scheme, which gives the upper bound of all IA-DCA schemes in terms of the system capacity. The effect of traffic dynamics is delt [sic] with in two steps. First, an asymptotic performance bound for the IA-DCA strategy is derived with the assumption of an arbitrarily large number of channels in the system. Then the performance bound for real wireless systems with the IA-DCA strategy is derived by alleviating this assumption. Our analytical result is compared with the performance bound drawn by Zander and Eriksson for reuse-partitioning DCA1 and some simulation results for IA-DCA in the literature. It turns out that the performance bound obtained in this work is much tighter than Zander and Eriksson\u27s bound and is in agreement with simulation results. 1only available for deterministic propagation model and downlink connection

Greenhouse gas emissions from cattle dung depositions in two Urochloa forage fields with contrasting biological nitrification inhibition (BNI) capacity

Grazing-based production systems are a source of soil greenhouse gas (GHG) emissions triggered by excreta depositions. The adoption of Urochloa forages (formerly known as Brachiaria) with biological nitrification inhibition (BNI) capacity is a promising alternative to reduce nitrous oxide (N2O) emissions from excreta patches. However, how this forage affects methane (CH4) or carbon dioxide (CO2) emissions from excreta patches remains unclear. This study investigated the potential effect of soils under two Urochloa forages with contrasting BNI capacity on GHG emissions from cattle dung deposits. Additionally, the N2O and CH4 emission factors (EF) for cattle dung under tropical conditions were determined. Dung from cattle grazing star grass (without BNI) was deposited on both forage plots: Urochloa hybrid cv. Mulato and Urochloa humidicola cv. Tully, with a respectively low and high BNI capacity. Two trials were conducted for GHG monitoring using the static chamber technique. Soil and dung properties and GHG emissions were monitored in trial 1. In trial 2, water was added to simulate rainfall and evaluate GHG emissions under wetter conditions. Our results showed that beneath dung patches, the forage genotype influenced daily CO2 and cumulative CH4 emissions during the driest conditions. However, no significant effect of the forage genotype was found on mitigating N2O emissions from dung. We attribute the absence of a significant BNI effect on N2O emissions to the limited incorporation of dung-N into the soil and rhizosphere where the BNI effect occurs. The average N2O EFs was 0.14%, close to the IPCC 2019 uncertainty range (0.01–0.13% at 95% confidence level). Moreover, CH4 EFs per unit of volatile solid (VS) averaged 0.31 g CH4 kgVS−1, slightly lower than the 0.6 g CH4 kgVS−1 developed by the IPCC. This implies the need to invest in studies to develop more region-specific Tier 2 EFs, including farm-level studies with animals consuming Urochloa forages to consider the complete implications of forage selection on animal excreta based GHG emissions

Electrochemical method for the determination of arsenic 'in the field' using screen-printed grid electrodes

This project describes development and problem solving efforts to realise a viable portable sensor for arsenic, applicable to drinking water. The work is the first dedicated effort towards this goal, after the preliminary investigations previously conducted at Cranfield University (Cooper, 2004 and Noh, 2005). Using polymeric gold ink BQ331 (DuPont Microcircuit Materials, Bristol, UK) as working electrode on screen printed strips, the electrochemical procedure was studied. Due to the wealth of research on electrochemical and non electrochemical methods for arsenic determination, this project attempts to capitalise on the unique advantages of the screen-printed gold surface. In particular, the issues surrounding the performance of the sensor were evaluated by electrochemical and spectroscopic means (including infrared, nuclear magnetic resonance and X-ray photoelectron spectroscopy). A number of custom screen printed electrodes were prepared in house comparing sensor performance on compositional factors. An interference coming from silver interaction with chloride in the reference electrode was identified. As such, the design of the sensor needs to change to include either an immobilising layer, such as Nafion, over the silver, or to omit screen-printed silver altogether. The Nafion was presumed to work by excluding (or at least much reducing) the passage of negatively charged chloride ions to the silver surface preventing formation of soluble silver chloride complexes. The design of the sensor was considered in light of performance and sensitivity. The screen-printed electrodes were cut to facilitate a microband design lending favourable diffusive to capacitive current characteristics. With this design, As(III) detection was demonstrated comfortably at 5 ppb (in a copper tolerant 4 M HCl electrolyte) without electrode need for additional preparation procedures. This is below the World Health Organisation (WHO) guideline and United States Environmental Protection Agency (USEPA) regulation level of 10 ppb in drinking water. The electrode materials are already mass manufacturable at an estimated cost less than £ 0.5 per electrode. Themicroband design could, in principle, be applied to mercury and other metal ions. The procedure for As(V) either with chemical or electrochemical reduction and determination still needs to be assessed. However, the presented electrode system offers a viable alternative to the colorimetric test kits presently employed around the world for arsenic in drinking water. Also, the Nicholson Method (Nicholson, 1965a), used for characterising electron transfer kinetics at electrode surfaces, was extended for application to rough surfaces using a fractal parameter introduced by Nyikos and Pajkossy (1988). This work includes mathematical derivation and numerical evaluation and gives a number of predictions for electrochemical behaviour. These predictions could not be tested experimentally, as yet, since the physical conditions must be carefully controlled

Sharing to improve services: a study of shared services capabilities

Motivation: Shared Services (SS) is a cost cutting and quality improvement strategy, which is receiving increasing attention from academics and practitioners. However, previous research focuses primarily on the potential benefits of these strategies; while very little research explains the role of SS resources and capabilities in the achievement of SS goals. The purpose of this thesis is to address this gap by explaining how SS resources and capabilities influence the achievement of SS goals. Approach: A multiple-case study approach is adopted, following a qualitative methodology, with data collection occurring at four SS organisations. Findings: This thesis introduces a taxonomy of SS resources and identifies three SS operational capabilities and seven SS dynamic capabilities, grouped into four areas of competence. Furthermore, this research uncovers the capability development process in an SS context, through the identification of the specific routines that precede each capability. Finally this research extends SS research, not only by identifying additional SS goals not mentioned by previous research, but also by recognising what specific SS capabilities contribute to what goals, thus uncovering the goal achievement process in a shared service centre. Academic Contributions: This research contributes to the negligible literature focusing on SS resources and capabilities and responds to the claims that a further understanding of shared services is needed in order to provide practitioners with advice and procedural guidelines on how to design, implement and manage SS. It also lays the foundation for future research on resources and capabilities in an SS context. Managerial Contributions: The findings enable managers to identify and further develop the necessary resources, routines and capabilities to achieve their specific SS goals. Additionally, this research supports managers in identifying additional goals they can achieve, considering the resources, routines and capabilities their SSCs already have

Electrochemical method for the determination of arsenic 'in the field' using screen-printed gold electrodes

This project describes development and problem solving efforts to realise a viable portable sensor for arsenic, applicable to drinking water. The work is the first dedicated effort towards this goal, after the preliminary investigations previously conducted at Cranfield University (Cooper, 2004 and Noh, 2005). Using polymeric gold ink BQ331 (DuPont Microcircuit Materials, Bristol, UK) as working electrode on screen printed strips, the electrochemical procedure was studied. Due to the wealth of research on electrochemical and non electrochemical methods for arsenic determination, this project attempts to capitalise on the unique advantages of the screen-printed gold surface. In particular, the issues surrounding the performance of the sensor were evaluated by electrochemical and spectroscopic means (including infrared, nuclear magnetic resonance and X-ray photoelectron spectroscopy). A number of custom screen printed electrodes were prepared in house comparing sensor performance on compositional factors. An interference coming from silver interaction with chloride in the reference electrode was identified. As such, the design of the sensor needs to change to include either an immobilising layer, such as Nafion, over the silver, or to omit screen-printed silver altogether. The Nafion was presumed to work by excluding (or at least much reducing) the passage of negatively charged chloride ions to the silver surface preventing formation of soluble silver chloride complexes. The design of the sensor was considered in light of performance and sensitivity. The screen-printed electrodes were cut to facilitate a microband design lending favourable diffusive to capacitive current characteristics. With this design, As(III) detection was demonstrated comfortably at 5 ppb (in a copper tolerant 4 M HCl electrolyte) without electrode need for additional preparation procedures. This is below the World Health Organisation (WHO) guideline and United States Environmental Protection Agency (USEPA) regulation level of 10 ppb in drinking water. The electrode materials are already mass manufacturable at an estimated cost less than £ 0.5 per electrode. Themicroband design could, in principle, be applied to mercury and other metal ions. The procedure for As(V) either with chemical or electrochemical reduction and determination still needs to be assessed. However, the presented electrode system offers a viable alternative to the colorimetric test kits presently employed around the world for arsenic in drinking water. Also, the Nicholson Method (Nicholson, 1965a), used for characterising electron transfer kinetics at electrode surfaces, was extended for application to rough surfaces using a fractal parameter introduced by Nyikos and Pajkossy (1988). This work includes mathematical derivation and numerical evaluation and gives a number of predictions for electrochemical behaviour. These predictions could not be tested experimentally, as yet, since the physical conditions must be carefully controlled.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Proceedings of the Third International Mobile Satellite Conference (IMSC 1993)

Satellite-based mobile communications systems provide voice and data communications to users over a vast geographic area. The users may communicate via mobile or hand-held terminals, which may also provide access to terrestrial cellular communications services. While the first and second International Mobile Satellite Conferences (IMSC) mostly concentrated on technical advances, this Third IMSC also focuses on the increasing worldwide commercial activities in Mobile Satellite Services. Because of the large service areas provided by such systems, it is important to consider political and regulatory issues in addition to technical and user requirements issues. Topics covered include: the direct broadcast of audio programming from satellites; spacecraft technology; regulatory and policy considerations; advanced system concepts and analysis; propagation; and user requirements and applications