205 research outputs found
Real-Time Single Channel Over-the-Air Data Acquisition for Digital Predistortion of 5G Massive MIMO Wireless Transmitters
No full textIEEE IWS 2019: Sixth IEEE MTT-S International Wireless Symposium, Guangzhou, China, 19-22 May 2019In this paper, a single channel over-the-air (OTA) data acquisition approach for real-time calibration of digital predistorter in multiple-input multiple-output transmitters is proposed. By using the data acquired from the far-field OTA tests, the output of each power amplifier (PA) can be virtually reconstructed and thus the linearization reference at the main beam direction can be accurately estimated. Digital predistortion (DPD) can therefore be effectively constructed without direct measurement at PA output. Experimental results demonstrate that the proposed scheme can accurately estimate far-field main beam data and the proposed DPD can achieve excellent linearization performance.Science Foundation IrelandNational Natural Science Foundation of China (NSFC
Descriptive statistics of nurses' responses to IWS and PES-NWI instrument.
No full text<p>Descriptive statistics of nurses' responses to IWS and PES-NWI instrument.</p
Pulu Keeling National Park Island-wide Survey (IWS) Waypoint Survey
No full text<p><b>Data Creation</b><br/>Survey Design: 132 waypoints have been randomly positioned on the IWS transit lines across the island. At each waypoint a 50m transect is placed either east or west from the waypoint (randomly assigned). The yellow crazy ant count method implemented in the Christmas Island IWS is then undertaken at these waypoints. Waypoints on the repeat transit lines are also repeat surveyed.<br/>Waypoint Survey counts: A 50m straight line transect is established randomly in either an east or west orientation at each waypoint. When establishing the transects: Navigate to the waypoint and lay out the tape measure in the pre-determined direction. Ant counts begin at 0m. There should be 11 survey points per transect (every 5m from 0-50m). At each survey point, ant cards are used to estimate ant activity per 30s: Carefully sweep loose material from a small patch of ground with your foot at every flagged survey point (every 5m). Place the ant card on the cleared ground and wait 15 seconds (timed with a stop watch/Gym Boss) to let any disturbance die down. Count the number of ants that enter the quadrat that the YCAs first appear in for the next 30 seconds (the maximum count is 100). Make a note in the comments if your count occurs near a nest, if it is raining or the ground is wet such that the count is not indicative of actual densities (e.g. 5m = nest). Ant counts should be conducted on sunny days when possible to ensure normal ant activity. It is important to record conditions that might influence the count. If it is damp or starts raining or the count is next to a nest, the counts may not be indicative of the real densities.<br/>Drift Description: Due to inclement weather and time constraints in 2012 only 56 randomly selected waypoints were surveyed. There was also only time to survey 4 of the waypoints a second time. Ideally, successive surveys should be conducted at the same time of year to enable such comparisons. Unfortunately, the survey in 2009 was conducted at the end of an extended dry period at the end of November, while the survey in 2012 was conducted in March (due to logistic constraints), which was one of the wettest months of the year. This difference is likely to have a strong effect on the behaviour, growth and detectability of most of the species we were surveying for; YCAs are less active in the wet, crabs are more active, nesting seabirds would change in distribution and abundance and the weeds are likely to be more visible and vigorous after prolonged rain.<br/>Waypoint survey - other observations: At each waypoint surveyors also assess: level of YCA tree traffic; presence of any scale insects; and presence of coral berry.<br/><b>Credit</b><br/>We at TERN acknowledge the Traditional Owners and Custodians throughout Australia, New Zealand and all nations. We honour their profound connections to land, water, biodiversity and culture and pay our respects to their Elders past, present and emerging.<br/>The project was jointly funded through the Caring for our Country Program and the Department of Sustainability, Environment, Water, Population and Communities (DSEWPAC). The Attorney Generals Department, the Crazy Ant Scientific Advisory Panel (CASAP), La Trobe University and Cocos Shire Council contributed to the project.<b>Purpose</b><br/>Pulu Keeling National Park (PKNP), an isolated coral atoll of 175ha, is part of the Cocos (Keeling) Islands, Australia's most remote island territory lying approximately 2900 kilometres northwest of Perth in the Indian Ocean. In order to monitor changes in the distributions of native and non-native species across the island, map the distribution of invasive weeds for future management, and to facilitate the detection of any major ecological changes, National Parks staff conduct an Island-wide Survey (IWS) to map the distribution of several flora and fauna species. The inaugural survey took place in November 2009, and a second survey followed in March 2012. This submission documents only the Waypoint Survey component of the IWS.Progress Code: completedMaintenance and Update Frequency: notPlannedThe dataset contains distribution data for the Yellow Crazy Ant (<i>Anoplolepis gracilipes</i>) and scale insects (eg <i>Parasaissetia nigra</i>, ,i>Dysmicoccus finitimus</i>), collected during the Waypoint Survey component of the Pulu Keeling National Park Island-wide Survey (IWS). The aim of the Waypoint Survey is to monitor densities of the invasive Yellow Crazy Ant (<i>Anoplolepis gracilipes</i>) and to detect establishment of any new scale insect species. The other components of the IWS (Transit Survey and Ink Card and Nocturnal Survey) are recorded in separate submissions
A new approach in optimal sensor placement for smart hydraulic monitoring in intermittent water supply (IWS) systems: A technical and financial analysis of the use of flow and pressure meters to detect hidden leaks in large cities in sub-Saharan Africa
No full textThis thesis proposes a novel design approach for a monitoring system that can detect hidden leaks in intermittent water supply (IWS) systems. Cities with IWS conditions in their drinking water network, such as Nairobi and Harare, often have a high percentage of non-revenue water (NRW) in their system. Estimations of the amount of NRW in these cities range from 40% to 50%, of which a large part is due to a leaky infrastructure. Intermittency of water supply is usually caused by a shortage of available supply, making it extra poignant to notice that these areas lose significant volumes of water. The leaks are also important locations for contaminant intrusion, which deteriorate the quality of drinking water. Additionally, intermittency of supply results in people using storage to fulfill themselves with their weekly water demand, which provides new challenges when constructing hydraulic models. Hidden leaks, which are leaks that do not appear at the surface, can be noticed in continuously supplied areas through reports of pressure deficiencies or the absence of supply. As these are regular circumstances in IWS areas, these hidden leaks are seldom noticed. Therefore, methods that are applicable in IWS systems need to be developed to detect these hidden leaks. This thesis proposes a new approach to detect hidden leaks in IWS areas with a smart hydraulic monitoring system. The approach optimizes the design of such a system in a district metered area (DMA) with IWS conditions in sub-Saharan Africa, by balancing information density and investment costs. By using as little equipment as possible, this optimization study aims to be not only scientifically and practically relevant, but also cost-effective. The methodology that was used to design the monitoring system makes use of a similar concept as the Dynamical Bandwidth Monitor (DBM), which is a smart hydraulic monitoring system that has been applied regularly in networks with continuous supply. The monitoring system consists of sensors that continuously measure flow or pressure and it compares these measurements to a range of expected values, attributing deviations from these expected values to a potential leak. A case study of Ashdown Park, a DMA with IWS conditions in Harare, was used to assess the performance of the design. The flow into this DMA and the pressure at its inlet had been monitored for one year. Two designs of the monitoring system were made, one which mainly consisted of flow sensors and one with mostly pressure sensors, to showcase which type of sensor could best be used in Ashdown Park. A hydraulic model was constructed for the DMA using pressure dependent outflow modelling. Daily demand patterns were constructed from analyzing the inflow measurements and used to calibrate the hydraulic model. The proposed calibration method assumes linear relationships between the demands and inlet pressure on one side and the pressure at a specific node and flow at a specific pipe on the other side. The range of expected flows and pressures within the DMA was calculated by Monte Carlo analyses, during which demand realizations were modelled by using a novel method which made use of a random weighted choice of demand, based on the outflow from a single tap. The ability of the monitoring system to detect leaks during different demand realizations was stored in a three-dimensional Boolean matrix, which was then used to determine the optimal sensor placement. A social and financial analysis, summarized in a business model canvas, shows more practical challenges and opportunities that could arise from implementing the monitoring system. The lessons learnt from this thesis were used to showcase whether the monitoring system could be applicable for IWS systems around the globe. Several conclusions can be drawn from the results of this thesis. The daily demand patterns in Ashdown Park showed a different pattern than in continuously supplied systems, showing less strong peaks. This could be due to a constant water demand for filling storage, leaks in the system or different consumer behaviour. The calibration method made it possible to model flows and pressures at the DMA inlet which were comparable to the measurements. The novel method to model demand realizations with a random weighted choice and a single tap capacity, showed promising results since the spread of the modelled inflow was well comparable to the spread of the inflow measurements. This standard tap capacity is especially suitable for IWS areas, since most people in IWS areas usually only have one tap directly connected to the water supply system and water end-use devices are not directly connected to the network. Furthermore, it was found that the water use behaviour of inhabitants of Ashdown Park had been more constant than the supply behaviour of the water utility. This irregular supply behaviour of the utility increased the difficulty of designing a pressure monitoring system. Using a flow monitoring system to detect leaks showed a better performance (leaks could be found on a daily basis in 25% of the pipes in the DMA) than using a monitoring system with pressure sensors (leaks could be found in 1% of the pipes). Making the monitoring system with pressure sensors dependent on the inlet pressure increased its performance (from 1% to 8.3%). Branched parts of the system were more favorable locations to place sensors and sensors at the DMA inlet were crucial for calibrating the hydraulic model. Practical barriers that were identified during this thesis were irregular operational schemes, unknown demand patterns and incomplete GIS data. Furthermore, costs can be saved as soon as leaks are detected, making the financial profitability very dependent on the performance of the system and the occurrence of leaks. The applicability of the monitoring system in IWS areas around the globe is determined by the priorities of a local water utility, its network characteristics and the ability of the local utility to overcome implementation barriers. The main limitations in this research are due to making some simplified assumptions, such as assuming a constant flow-rate from the tap in all households in Ashdown Park, and due to a lack of understanding of the local situation, since this research was performed in the Netherlands. To validate assumptions and get better understanding of the local situation, it is advised to conduct follow-up research at the location of interest. Especially a pilot project of the proposed monitoring system would likely find more practical barriers and limitations than could be thought off in this thesis and therefore bring more valuable information for the implementation of a smart hydraulic monitoring system. If prioritized, properly installed and operated, the proposed smart hydraulic monitoring system could generate substantial water savings and provide many social benefits, such as an increased access to clean drinking water and employment opportunities. Above all, it can assist a local utility with fulfilling their responsibility: supplying people with the basic need of drinking water.Water Managemen
Caste, mistrust and municipal inaction: The interwoven barriers for the integration of waste pickers in India
No full textSolid waste management in low- and middle-income countries like India faces significant challenges due to the increasing waste generation that surpasses the current capacity. Therefore, the informal waste sector (IWS) is more vital than ever in handling consumer waste alongside municipal solid waste management (SWM) systems. However, the integration of the IWS into formal waste management systems remains unresolved due to adverse social and economic conditions. This study focuses on identifying the root causes that hinder the integration of the IWS in India's waste management system, using the city of Chennai as a case study. Adopting an institutional perspective, we analyse the institutional landscape of the waste management system, considering both formal rules (in policy documents) and informal rules (i.e., social norms and routines). The institutional network analysis reveals a significant misalignment in perceptions among governance levels concerning the integration of the IWS. The study shows a considerable gap between rules-in-form and rules-in-use, leading to 1) Preclusion of waste pickers in collecting door-to-door source-segregated waste (i.e., recyclables). 2) Unfair pricing in transactions with small aggregators. 3) Lack of ID cards for waste pickers. These barriers are ultimately rooted in caste discrimination, misalignment between governance levels, and the exclusion of waste pickers in the policymaking process. In conclusion, understanding and rectifying the institutional gaps and discriminatory practices are essential steps towards effectively integrating the IWS in India's waste management system, promoting a more inclusive and sustainable approach to waste management.System Engineerin
Review of hydraulic modelling approaches for intermittent water supply systems
No full textIntermittent water supply (IWS) is widely used around the world, and with the increase in population and predicted future water scarcity, IWS applications seem to continue. While most of the existing studies on water supply concentrate on continuous water supply (CWS), the research focused on the IWS is now becoming mainstream. Hydraulic modelling is an effective tool for the process of planning, design, rehabilitation, and operation of water distribution systems. It helps significantly in engineers’ decision-making processes. The necessity of modelling IWS systems arises from the complexity and variety of problems caused by intermittency. This paper offers a review of the state-of-the-art IWS modelling and identifies the key strengths and limitations of the available approaches, and points at potential research directions. Currently, neither computer software nor a practically used approach is available for modelling IWS. For a rigorous simulation of IWS, system characteristics first need to be understood, i.e., the user behaviour under pressure-deficient conditions, water losses, and filling and emptying processes. Each of them requires further attention and improvement. Additionally, the necessity of real data from IWSs is stressed. Accurate modelling will lead to the development of improved measures for the problems caused by intermittency.</p
Intermittent Water Supply Management, Household Adaptation, and Drinking Water Quality: A Comparative Study in Two Chinese Provinces
No full textIntermittent water supply (IWS) is a relatively common phenomenon across the world as well as in rural and peri-urban areas across China, though there has been little IWS-focused research from China published to date. IWS consumers typically adopt a range of strategies to cope with insufficient water supply, poor drinking water quality, and associated inconveniences. In this study, we collected a range of data from small-scale utilities and households in two IWS systems and two continuous water supply (CWS) systems, as well as from comparison groups, in Shandong and Hubei provinces. Data collection included water quality testing, interviews, and surveys on behavioral adaptations, coping strategies, water-related health perceptions, and other metrics of consumer satisfaction. Overall, we found that the IWS coping strategies employed in northern China (Shandong) were associated with generally safe, but inconvenient, water access, whereas adaptation strategies observed in southern China (Hubei) appeared to improve convenience, but not water quality. Compared to the CWS comparison groups, we did not observe significant differences in water- and sanitation-related behaviors in the IWS groups, suggesting interventions to increase adaptive and protective behaviors at the household level might further improve safe water access for households living with IWS. Overall, although the water supply infrastructure in these study areas appeared to be in relatively good condition, in contrast to reported data on IWS systems in other countries, we observed multiple risk factors associated with the water treatment and distribution processes in these IWS systems. Among policy recommendations, our results suggest that the implementation of Water Safety Plans in China would likely improve the management of drinking water treatment and, by extension, safe drinking water supply under conditions of IWS
Exploring the Viability of Exposure to Stories of Individuals Who Stutter as a Learning Tool
No full textBackground A large body of literature suggests that individuals who stutter, (“IWS”), are subjected to negative stereotypical attitudes and perceptions held by speech language pathologists (“SLPs”). Although there has been improvement in SLPs’ perceptions of IWS, there continues to be a need to provide student SLPs with first hand experiences with stuttering to facilitate the development of an empathic understanding of the impact of stuttering. A new method was investigated by Connatty et al. (2010), (the “Connatty study”) to engender in student SLPs an empathic understanding of the impact of stuttering. The Connatty study used qualitative methods in which the student SLPs were researcher-participants. Participants used reflective journaling to record their reactions as they viewed video-recordings of IWS. The author was a participant in the Connatty study during the data collection and reflection summary phases only. Her data was used in the Connatty study’s thematic analysis completed by the remaining participants. Purpose The purpose of this study is to provide a nuanced understanding of the individual reflections of a student SLP (i.e., the author) who participated in the Connatty study and to examine the congruence between the author’s summarized reflections and the thematic results of the Connatty study. Conclusion The author concluded that viewing video-recordings of IWS talking about stuttering is a viable method for developing in student SLPs an empathic understanding of stuttering and of IWS. She also indicated that the project helped her to develop an empathetic understanding of IWS. Congruency with the Connatty study is discussed
Integration of the informal waste sector in the Indian city of Chennai: a case study: Application of the Institutional Network Analysis to a municipal waste management system
No full textIndia has experienced rapid industrialisation which has led to a significant increase in consumption and, in turn, in waste generation. The informal waste sector (IWS) plays a key role in managing consumer waste. However, this sector is subject to negative social and economic conditions and its integration in formal systems remains unsolved. Understanding institutions as strategies, norms and rules that guide the behaviour of actors, and acknowledging that institutions are connected to one another, this research focuses on the waste management system of Chennai, India to answer How the institutional network of the waste system influence the integration of the informal waste sector? The Institutional Network Analysis method is applied to data obtained from desk research and stakeholder interviews. The network analysis reveals the following results: 1) the Municipality is the major bottleneck for the sector's integration; 2) the large gap between rules-in-use and rules-in-form (i.e., IWS is legally recognised since 2016 but integration has not happened in practice); 3) it is not a problem of policy implementation, in fact the problem lies in the stages of agenda setting and policy formulation; 4) disagreement between policy levels, between the ones that create the policy and those that have to implement it (high-level policy makers agree on the need to integrate the IWS while low-level policy makers do not deem it as a priority).Industrial Ecolog
Development of a fast omni-directional treadmill platform for immersive locomotion interface
No full textTo realize an immersive locomotion interface (LI) of a user in virtual reality (VR), a stationary-type device should be allowed to perform various locomotion of human being (walking, running, sideway moving etc.) in any direction and intentional speed. Thus, a platform providing an immersive LI should maintain a user in a reference position even when moving at a free speed and any direction. To implement the mentioned functions above, the following technologies are required; i) An omnidirectional ground generation mechanism capable of realizing a 2-dimensional ground like the real ground, and ii) A control method that adapts the user's locomotion velocity by estimating the intended walking speed (IWS) through detecting user location and action. Currently, developed omnidirectional treadmills (ODTs) are representative devices that can infinitely generate the ground in all directions. Therefore, an ODT can work as an immersive walking interface platform by applying LI controller realizing the functionality of a user-driven treadmill (UDT) to follow the estimated IWS for the adaptation of a user locomotion speed and providing spatial sensation with visual feedback via VR.
However, existing ODTs are heavy and complex, and operate at low speeds. This limits fast user motion and prevents natural interactions in real applications such as military training programs and interactive games. Moreover, in terms of LI controller, robustness of the user position must be ensured by sensitively estimating and accurately converging to IWS to achieve safe and immersive interface. The existing IWS estimation using a linear observer with the cart model (1st order dynamics) can exponentially converge to the true IWS. However, when the estimation sensitivity is increased by increasing the gain, this method causes severe postural instability due to the generation of excessive anomalous forces. Thus, the existing method has an implicit limitation with regards to increasing the position robustness because of the postural instability issues.
To develop an ODT platform that increases LI immersion for a user, the reserch presents a method to solve the problems of existing ODTs and developed LI controllers, and is classified into three sections as follows:
An ODT based on rack and pinion mechanism concept, and design of cart model-based 2-dimensional locomotion interface: It introduces a novel locomotion interface device with running capability, which uses an ODT with a new power transmission mechanism and a locomotion controller that enables the user to make fast movements. As a result of the improved power transmission performance due to the simple and relatively lightweight structure, the proposed two-dimensional treadmill can generate a maximum speed of 3 m/s, with an acceleration of 3 m/s2. Moreover, through a pilot test with the proposed locomotion interface device, we verified that the fast directional changes during walking and running with the designed speed adaptation controller do not exceed the acceleration performance of the proposed system.
Design of inverted pendulum gait model-based locomotion interface and its experiment of conducting forward and sideway locomotion: To simultaneously achieve sensitive and accurate IWS estimation while reducing postural instability on a UDT, in addition to the cart model, we have also utilized the inverted pendulum-based gait model (IPGM) as a 2nd order dynamic to estimate the intentional walking acceleration (IWA) generated by the ankle torque. Thus, the proposed IWS prediction method uses the cart model for accurate convergence to IWS and the IPGM to follow sensitively the change in the IWS. In the proposed method, the internal states of the existing observers applied to the 1st and 2nd order dynamics are shared recursively to estimate the ankle torque acting as a disturbance for the IPGM and to sensitively predict the change in the IWS.
Preliminary development of a compact omnidirectional treadmill based on a novel helical gear transmission and its pilot test: A mechanical design of a novel actuation system based on helical transmission for an ODT is presented. Conventional ODTs can realize omnidirectional motion; however, they have issue such as limited motion performance due to low transmission efficiency, excessive thickness because of increasing actuation space, and loud power transmission noise. The proposed design solves this drawback by means of 2-layer meshes consist of helical pulleys and helical gears. The omnidirectional motion is driven by the first layer as the helical pulley mesh, and a motor power for first layer actuation is transmitted by synchronized actuation of the second layer as helical gear mesh. Compared to the ODT developed by the author previously based on spur transmission, the helical transmission mechanism only increases the length in the direction of the rotation axis instead of increasing the diameter to increase the gear tooth coupling, the proposed transmission can realize compact and super-thin actuation space. Moreover, it can potentially reduce the noise compared to spur transmission (Rack and pinion) because of utilizing the helical transmission.
Due to the wide range of movement speeds and acceleration capabilities of the rack and pinion based ODT, it can enhance the immersive experience in various VR environments due to increasing motion performance. Experiment of the designed IPGM based IWS estimation show that the proposed method can significantly facilitate the users in following a profile of desired walking speeds more accurately than the existing IWS estimation method under the same position robustness setup. The pilot experiment of the preliminary developed ODT with the helical actuation mechanism to show how it works, has been conducted to check the kinematic feasibility when performing omnidirectional motion.Docto
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