13 research outputs found

    SELECTING THE TIME OF CONCENTRATION CONSIDERING GROUNDWATER DEPTH AND RUNOFF COEFFICIENT IN THE ARGENTINIAN PAMPA REGION: Seleรงรฃo do tempo de concentraรงรฃo considerando profundidade das รกguas subterrรขneas e coeficiente de escoamento na regiรฃo do pampa argentino

    Get PDF
    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 Venturaโ€™s and Pasiniโ€™s equations are suitable to determine Tc under water deficit, while Izzardโ€™s and Kinematic Wave equations are appropriate for saturated conditions of the system.El tiempo de concentraciรณn (Tc) es uno de los parรกmetros mรกs sensibles para calcular el escurrimiento mรกximo en una cuenca y juega un papel fundamental en la determinaciรณn de los caudales de diseรฑo. En este trabajo se evalรบa la consistencia de las ecuaciones que componen los mรฉtodos analรญticos utilizados para estimar el Tc mediante el contraste de eventos observados a partir de la aplicaciรณn del mรฉtodo grรกfico en una cuenca de llanura ubicada en la regiรณn Pampeana, Argentina. La metodologรญa utilizada considera la complejidad del proceso de generaciรณn de escorrentรญa y la dinรกmica hรญdrica de la regiรณn teniendo en cuenta el anรกlisis de la profundidad del agua subterrรกnea y el coeficiente de escorrentรญa. 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 dรฉficit hรญdrico, mientras que las ecuaciones de Izzard y Onda Cinemรกtica son adecuadas para condiciones de saturaciรณn del sistema

    ๋น„๊ต์šฐ์œ„์˜ ๋™ํƒœ์  ๋ณ€ํ™”์™€ ๊ฒฝ์ œ์„ฑ์žฅ ๊ฐ„์˜ ๊ด€๊ณ„์— ๋Œ€ํ•œ ์‹ค์ฆ๋ถ„์„ ์—ฐ๊ตฌ

    Get PDF
    ํ•™์œ„๋…ผ๋ฌธ(๋ฐ•์‚ฌ) -- ์„œ์šธ๋Œ€ํ•™๊ต๋Œ€ํ•™์› : ์‚ฌํšŒ๊ณผํ•™๋Œ€ํ•™ ๊ฒฝ์ œํ•™๋ถ€, 2023. 2. ์ด๊ทผ.๋ณธ ๋…ผ๋ฌธ์€ ๊ฒฝ์ œ์„ฑ์žฅ๊ณผ ๋™ํƒœ์  ๋น„๊ต์šฐ์œ„ ๋ณ€ํ™” ๊ฐ„์˜ ๊ด€๊ณ„๋ฅผ ๋ถ„์„ํ•˜๋Š” ๋ฐ ๋ชฉ์ ์ด ์žˆ๋‹ค. ๊ฒฝ์ œ์„ฑ์žฅ ์ „๋žต์˜ ์ผํ™˜์œผ๋กœ ์ˆ˜์ถœ ๋‹ค๋ณ€ํ™”์™€ ์ˆ˜์ถœ ํŠนํ™”์˜ ๊ฒฝ์ œ์  ํšจ๊ณผ์— ๋Œ€ํ•œ ๋…ผ์˜๊ฐ€ ์ง€์†๋˜๋Š” ๊ฐ€์šด๋ฐ ๋ณธ ์—ฐ๊ตฌ๋Š” ์žฅ๊ธฐ์ ์ธ ๊ฒฝ์ œ์„ฑ์žฅ์„ ์œ„ํ•œ ์ˆ˜์ถœ์ „๋žต์„ ๋ชจ์ƒ‰ํ•ด ๋ณด๊ณ ์ž ํ•˜๋Š” ๊ด€์ ์—์„œ ์ถœ๋ฐœํ•˜์˜€๋‹ค. ๋ณธ ์—ฐ๊ตฌ๋Š” ๊ฐœ๋„๊ตญ์˜ ์„ฑ๊ณต์ ์ธ ๊ฒฝ์ œ๋ฐœ์ „ ๋ชจ๋ธ๋กœ ๊ฑฐ๋ก ๋˜๋Š” ํ•œ๊ตญ๊ณผ ๋Œ€๋งŒ์˜ ๋ณ€ํ™”ํ•˜๋Š” ์ˆ˜์ถœํŠนํ™” ํŒจํ„ด์— ์ฃผ๋ชฉํ•˜์˜€๋‹ค. ํ•œ๊ตญ๊ณผ ๋Œ€๋งŒ์˜ ์ˆ˜์ถœ์€ ์ง€์†์ ์œผ๋กœ ์†Œ์ˆ˜์˜ ์ƒ์œ„ ์ˆ˜์ถœํ’ˆ์— ์ง‘์ค‘๋˜์–ด ์žˆ๋Š” ํ•œํŽธ ์ƒ์œ„ ์ˆ˜์ถœํ’ˆ์ด ํฌ๊ฒŒ ๋ณ€ํ™”ํ•œ ํŠน์ง•์„ ๋ณด์˜€๋‹ค. ๋˜ํ•œ ๋ณ€ํ™”ํ•˜๋Š” ์ƒ์œ„ ์ˆ˜์ถœํ’ˆ ๊ตฌ์„ฑ์€ ์ž์› ๋ฐ ๋…ธ๋™์ง‘์•ฝ์‚ฐ์—… ์ค‘์‹ฌ์—์„œ ์ž๋ณธ์ง‘์•ฝ์‚ฐ์—… ์ค‘์‹ฌ์œผ๋กœ ์‚ฐ์—…์  ๋„์•ฝ์„ ํ•œ ๊ฒƒ์œผ๋กœ ๊ด€์ธก๋˜์—ˆ๋‹ค. ํ•œ๊ตญ๊ณผ ๋Œ€๋งŒ์˜ ๊ณตํ†ต๋œ ์ˆ˜์ถœ ํŠนํ™”์˜ ๋™ํƒœ์  ๋ณ€ํ™” ํ˜„์ƒ์€ ๋น„๊ต์šฐ์œ„ ๋ณ€ํ™”๊ฐ€ ๊ฒฝ์ œ์„ฑ์žฅ์˜ ์ฃผ์š”ํ•œ ๊ฒฐ์ •์š”์ธ์ž„์„ ์ฃผ์žฅํ•œ ์ด๋ก ์—ฐ๊ตฌ์™€ ๋งฅ๋ฝ์„ ๊ฐ™์ด ํ•œ๋‹ค. ๋™์•„์‹œ์•„ ์ฃผ์š”๊ตญ์˜ ์ˆ˜์ถœํŒจํ„ด๊ณผ ๋™ํƒœ์  ๋น„๊ต์šฐ์œ„ ๋ณ€ํ™”์— ๋Œ€ํ•œ ์ด๋ก ์—ฐ๊ตฌ๋ฅผ ๊ธฐ๋ฐ˜์œผ๋กœ ๋ณธ ์—ฐ๊ตฌ๋Š” ๋น„๊ต์šฐ์œ„์˜ ๋™ํƒœ์  ๋ณ€ํ™”๊ฐ€ ๊ฒฝ์ œ์„ฑ์žฅ์— ๋ฏธ์น˜๋Š” ์žฅ๊ธฐ์ ์ธ ํšจ๊ณผ๋ฅผ ๋ถ„์„ํ•œ๋‹ค. ๋ถ„์„์—๋Š” ๋‚ด์ƒ์„ฑ์„ ํ†ต์ œํ•œ ํšก๋‹จ๋ฉด ๋™ํƒœ์  ํŒจ๋„๋ถ„์„ ๋ฐฉ๋ฒ•๋ก ์ธ ์‹œ์Šคํ…œ GMM ์ถ”์ •๊ณผ ํ•จ๊ป˜ ๋ณ€์ˆ˜๋“ค ๊ฐ„ ํ”ผ๋“œ๋ฐฑ ๊ด€๊ณ„๋ฅผ ๊ณ ๋ คํ•จ์œผ๋กœ์จ ๋‚ด์ƒ์„ฑ์„ ํ†ต์ œํ•˜๋ฉฐ ์„ค๋ช…๋ณ€์ˆ˜์˜ ์žฅ๊ธฐ์  ํšจ๊ณผ๋ฅผ ๋ถ„์„ํ•˜๋Š” ์‹œ๊ณ„์—ด ํŒจ๋„๋ถ„์„ ๋ฐฉ๋ฒ•๋ก ์˜ ํ•˜๋‚˜์ธ CS-DL (cross-sectionally augmented distributed lag) ์ถ”์ •์„ ๊ฒฝ์ œ์„ฑ์žฅ ๋ชจํ˜•์— ์ ์šฉํ•˜์˜€๋‹ค. ๋…ผ๋ฌธ์˜ ํ•ต์‹ฌ๊ธฐ์—ฌ๋Š” ๋‹ค์Œ๊ณผ ๊ฐ™๋‹ค. ์ฒซ์งธ, ์ƒˆ๋กœ์šด ์ƒ์œ„ ์ˆ˜์ถœํ’ˆ ์ฐฝ์ถœ๋กœ ๋น„๊ต์šฐ์œ„ ๋ณ€ํ™”๋ฅผ ์‚ฌํ›„์ ์œผ๋กœ ์ถ”์ •ํ•˜๋Š” ์ธ๋ฑ์Šค๋ฅผ ์ œ์‹œํ•˜๊ณ  ๋น„๊ต์šฐ์œ„ ๋ณ€ํ™”๊ฐ€ ์žฅ๊ธฐ์ ์ธ ๊ฒฝ์ œํšจ๊ณผ๊ฐ€ ์žˆ์Œ์„ ์‹ค์ฆ์ ์œผ๋กœ ๋ณด์˜€๋‹ค. ์ด๋Ÿฌํ•œ ๋ถ„์„๊ฒฐ๊ณผ๋Š” ๊ฒฝ์ œ๋ณต์žก์„ฑ์ง€์ˆ˜ (economic complexity index: ECI)๋ฅผ ํฌํ•จํ•œ ์ถ”๊ฐ€์ ์ธ ํ†ต์ œ์—๋„ ์ผ๊ด€๋˜๊ฒŒ ๋‚˜ํƒ€๋‚œ ํ•œํŽธ, ECI๋Š” CS-DL ๋ชจํ˜•์—์„œ๋Š” ํ†ต๊ณ„์  ์œ ์˜์„ฑ์ด ์—†๋Š” ๊ฒƒ์œผ๋กœ ๋‚˜ํƒ€๋‚ฌ๋‹ค. ์ด๋Ÿฌํ•œ ๋ถ„์„๊ฒฐ๊ณผ๋Š” ๊ตญ๊ฐ€๋ณ„ ํŠน์„ฑ์— ๋Œ€ํ•œ ๊ณ ๋ ค ์—†์ด ์„ ์ง„๊ตญ์˜ ํŠนํ™”ํŒจํ„ด์„ ์ง€ํ–ฅํ•˜๋Š” ๊ฒƒ์ด ๋น„์„ ์ง„๊ตญ์˜ ์žฅ๊ธฐ์ ์ธ ๊ฒฝ์ œ์„ฑ์žฅ์„ ๋ณด์žฅํ•˜์ง€ ์•Š๋Š”๋‹ค๋Š” ํ•จ์˜๋ฅผ ์ง€๋‹Œ๋‹ค. ๋‘˜์งธ, ๋น„๊ต์šฐ์œ„ ๋ณ€ํ™” ์ธ๋ฑ์Šค๋ฅผ ํ†ตํ•ด ์ˆ˜์ถœํŠนํ™”์™€ ๋‹ค๋ณ€ํ™”๋Š” ์ƒ๋ฐ˜๋œ ๊ฐœ๋…์ด ์•„๋‹Œ ์ƒํ˜ธ ์—ฐ๊ด€๋œ ๊ฐœ๋…์ž„์„ ๋ณด์˜€๋‹ค. ์ด๋Š” ์ผ๋ฐ˜์ ์œผ๋กœ ์ƒˆ๋กœ์šด ํŠนํ™” ์ฐฝ์ถœ์ด ์ˆ˜์ถœ ๋‹ค๋ณ€ํ™”๋กœ ์ด์–ด์ง„๋‹ค๋Š” ๋ฐ์— ๊ธฐ์ธํ•œ๋‹ค. ์…‹์งธ, ๋น„์„ ์ง„๊ตญ์„ ๋Œ€์ƒ์œผ๋กœ ๊ธฐ์ˆ ์ˆ˜์ค€๋ณ„ ๋น„๊ต์šฐ์œ„ ๋ณ€ํ™”์˜ ์žฅ๊ธฐ์ ์ธ ๊ฒฝ์ œํšจ๊ณผ๋ฅผ ๋ถ„์„ํ•œ ๊ฒฐ๊ณผ ๊ณ ๊ธฐ์ˆ  ๊ธฐ๋ฐ˜ ๋น„๊ต์šฐ์œ„ ๋ณ€ํ™”, ์ €๊ธฐ์ˆ  ์ง€๋ฐ˜ ๋น„๊ต์šฐ์œ„ ๋ณ€ํ™”์˜ ๊ฒฝ์ œ์  ํšจ๊ณผ๋Š” ๊ฐ๊ฐ ์œ ์˜ํ•˜์ง€ ์•Š์€ ๊ฒƒ์œผ๋กœ ๋‚˜ํƒ€๋‚ฌ๋‹ค. ์ด๋Š” ๊ณ ๊ธฐ์ˆ  ๊ธฐ๋ฐ˜ ๋น„๊ต์šฐ์œ„ ๋ณ€ํ™”, ์ฆ‰ ์„ ์ง„๊ตญ์˜ ํŠนํ™”๊ตฌ์กฐ๊ฐ€ ๊ฒฝ์ œ์  ํšจ๊ณผ๊ฐ€ ์žˆ์Œ์„ ๋ณด์ธ ์„ ํ–‰์—ฐ๊ตฌ์™€ ๋Œ€์กฐ๋˜๋Š” ๊ฒฐ๊ณผ์ด๋‹ค. ํ•œํŽธ ๋น„์„ ์ง„๊ตญ์„ ๋Œ€์ƒ์œผ๋กœ ํ•œ CS-DL ๋ถ„์„๊ฒฐ๊ณผ 1992๋…„์„ ๊ธฐ์ ์œผ๋กœ ๊ธฐ์ˆ ์ฆ์ง„์„ ๋™๋ฐ˜ํ•œ ๋น„๊ต์šฐ์œ„ ๋ณ€ํ™”๋Š” ์žฅ๊ธฐ์ ์ธ ๊ฒฝ์ œํšจ๊ณผ๊ฐ€ ์žˆ๋Š” ๊ฒƒ์œผ๋กœ ๋‚˜ํƒ€๋‚ฌ๋‹ค. ์ด๋Š” ๋‹จ๊ธฐ์ ์œผ๋กœ ํ˜„ ์‹œ์ ์˜ ๋น„๊ต์šฐ์œ„ ๊ตฌ์กฐ๋ฅผ ๋ฐ›์•„๋“ค์ด๋˜ ์žฅ๊ธฐ์  ๊ด€์ ์—์„œ ๋น„๊ต์šฐ์œ„ ์‚ฐ์—…์˜ ๊ธฐ์ˆ ์  ์ฆ์ง„์„ ๋„๋ชจํ•˜๋Š” ์ ์ง„์ ์ธ ์ „๋žต์ด ๋น„์„ ์ง„๊ตญ์—๊ฒŒ ์œ ์šฉํ•œ ์„ฑ์žฅ์ „๋žต์ด ๋  ์ˆ˜ ์žˆ์Œ์„ ์‹œ์‚ฌํ•œ๋‹ค.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 Asiaโ€”Korea and Taiwanโ€”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 100๋ฐ•

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

    Get PDF
    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-๏ฟผend. 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

    Get PDF
    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

    Get PDF
    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 (0.01โ€“0.13% at 95% confidence level). Moreover, CH4 EFs per unit of volatile solid (VS) averaged 0.31 g CH4 kgVSโˆ’1, slightly lower than the 0.6 g CH4 kgVSโˆ’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

    Management of customizable software-as-a-service in cloud and network environments

    Get PDF

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

    Get PDF
    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 ยฃ 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

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

    Get PDF
    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 ยฃ 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)

    Get PDF
    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
    corecore