Academic literature on the topic 'Average residence time'
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Journal articles on the topic "Average residence time"
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Landfeld, A., R. Žitný, M. Houška, K. Kýhos, and P. Novotná. "Residence time distribution during egg yolk pasteurisation." Czech Journal of Food Sciences 20, No. 5 (2011): 193–201. http://dx.doi.org/10.17221/3531-cjfs.
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This work describes the determination of the average residence times during egg yolk – and whole liquid eggs pasteurisation in an industrial pasteurisation equipment (plate pasteuriser + tube holder). For the detection of the impulse the conductivity method was used. Conductivity was then monitored using the bridge method. In the system, the total of 3 probes were placed. To mark the particles of the flowing product, salted yolk with the content of salt of 1.3 or 1.8% was used. In addition, rheological properties of pasteurised yolk were determined at the temperatures of 5, 25, 45, and 65°C. Based on the geometry of the channels in the individual sections of the pasteurisation equipment, the character of the flow was estimated using the Re criterion and was found to be laminar in all parts of the system. The work includes the comparison of the average residence times obtained by (a) the method of volumes, (b) the analysis of the conductivity response, (c) the estimate made by using the TUPLEX software, and (d) the estimate of the peaks of the conductivity response.  
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Vergnes, B. "Calculation of Average Residence Time in a Ko-kneader." International Polymer Processing 26, no. 5 (2011): 587–89. http://dx.doi.org/10.3139/217.2528.
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Osácar, Carlos, Manuel Membrado, and Amalio Fernández-Pacheco. "Brief communication: Residence time of energy in the atmosphere." Nonlinear Processes in Geophysics 27, no. 2 (2020): 235–37. http://dx.doi.org/10.5194/npg-27-235-2020.
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Abstract. In atmospheric chemistry, a parameter called residence time is defined for each gas as T=M/F, where M represents the mass of the gas in the atmosphere and F is the total average influx or outflux, which in time averages are equal. In this brief communication, we extend this concept from matter to energy which is also a conservative quantity and estimate the average residence time of energy in the atmosphere, which amounts to about 58 d. A similar estimation for the residence time of energy in the Sun is of the order of 107 years, which agrees with the Kelvin–Helmholtz timescale.
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van der Ent, Ruud J., and Obbe A. Tuinenburg. "The residence time of water in the atmosphere revisited." Hydrology and Earth System Sciences 21, no. 2 (2017): 779–90. http://dx.doi.org/10.5194/hess-21-779-2017.
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Abstract. This paper revisits the knowledge on the residence time of water in the atmosphere. Based on state-of-the-art data of the hydrological cycle we derive a global average residence time of 8.9 ± 0.4 days (uncertainty given as 1 standard deviation). We use two different atmospheric moisture tracking models (WAM-2layers and 3D-T) to obtain atmospheric residence time characteristics in time and space. The tracking models estimate the global average residence time to be around 8.5 days based on ERA-Interim data. We conclude that the statement of a recent study that the global average residence time of water in the atmosphere is 4–5 days, is not correct. We derive spatial maps of residence time, attributed to evaporation and precipitation, and age of atmospheric water, showing that there are different ways of looking at temporal characteristics of atmospheric water. Longer evaporation residence times often indicate larger distances towards areas of high precipitation. From our analysis we find that the residence time over the ocean is about 2 days less than over land. It can be seen that in winter, the age of atmospheric moisture tends to be much lower than in summer. In the Northern Hemisphere, due to the contrast in ocean-to-land temperature and associated evaporation rates, the age of atmospheric moisture increases following atmospheric moisture flow inland in winter, and decreases in summer. Looking at the probability density functions of atmospheric residence time for precipitation and evaporation, we find long-tailed distributions with the median around 5 days. Overall, our research confirms the 8–10-day traditional estimate for the global mean residence time of atmospheric water, and our research contributes to a more complete view of the characteristics of the turnover of water in the atmosphere in time and space.
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Liu, Zhe, Hao Wei, Guangshan Liu, and Jing Zhang. "Simulation of water exchange in Jiaozhou Bay by average residence time approach." Estuarine, Coastal and Shelf Science 61, no. 1 (2004): 25–35. http://dx.doi.org/10.1016/j.ecss.2004.04.009.
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Tinker, Sarah C., Christine L. Moe, Mitchel Klein, et al. "Drinking water residence time in distribution networks and emergency department visits for gastrointestinal illness in Metro Atlanta, Georgia." Journal of Water and Health 7, no. 2 (2009): 332–43. http://dx.doi.org/10.2166/wh.2009.022.
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We examined whether the average water residence time, the time it takes water to travel from the treatment plant to the user, for a zip code was related to the proportion of emergency department (ED) visits for gastrointestinal (GI) illness among residents of that zip code. Individual-level ED data were collected from all hospitals located in the five-county metro Atlanta area from 1993 to 2004. Two of the largest water utilities in the area, together serving 1.7 million people, were considered. People served by these utilities had almost 3 million total ED visits, 164,937 of them for GI illness. The relationship between water residence time and risk for GI illness was assessed using logistic regression, controlling for potential confounding factors, including patient age and markers of socioeconomic status (SES). We observed a modestly increased risk for GI illness for residents of zip codes with the longest water residence times compared with intermediate residence times (odds ratio (OR) for Utility 1 = 1.07, 95% confidence interval (CI)=1.03, 1.10; OR for Utility 2 = 1.05, 95% CI = 1.02, 1.08). The results suggest that drinking water contamination in the distribution system may contribute to the burden of endemic GI illness.
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Liu Ya-Chun. "A new method for monitoring the average residence time of atmospheric particulate matter." Acta Physica Sinica 62, no. 9 (2013): 092301. http://dx.doi.org/10.7498/aps.62.092301.
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Li, S. H., S. Yang, H. R. Yang, et al. "Particle Holdup and Average Residence Time in the Cyclone of a CFB Boiler." Chemical Engineering & Technology 31, no. 2 (2008): 224–30. http://dx.doi.org/10.1002/ceat.200700264.
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Liu, Taibei, Weijian Zhou, Peng Cheng, and G. S. Burr. "A Survey of the 14C Content of Dissolved Inorganic Carbon in Chinese Lakes." Radiocarbon 60, no. 2 (2017): 705–16. http://dx.doi.org/10.1017/rdc.2017.113.
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AbstractWe present radiocarbon (14C) measurements of dissolved inorganic carbon (DIC) from surface waters of 11 lakes, widely distributed in China. Surface lake water DIC F14C values show distinct differences, and we relate these to the physical exchange character (“open” or “closed”) of each lake. Open lakes studied here generally have lower DIC F14C values than closed lakes. We present a simple model of a lake water cycle to calculate an average residence time for each lake. Comparisons between lake DIC F14C and average residence time shows that the DIC F14C increases with the average residence time and reflects a steady-state.
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Li, Tingting, Yu Zhu, Liyue Lin, Wenqian Ke, and Baoyu Xiao. "Spatial differentiation and influencing factors of floating population’s length of residence willingness." International Journal of Population Studies 7, no. 2 (2022): 27. http://dx.doi.org/10.18063/ijps.v7i2.1363.
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Based on the dynamic monitoring data of China’s floating population in 2018, according to the length of time that the floating population is willing to stay in the inflow area, the residence intention is divided into three types: short-term residence intention, long-term residence intention and permanent residence intention. The spatial differentiation and influencing factors of different types of residence intention of floating population in cities at and above the prefecture level in China are compared and analyzed by using spatial analysis technology and hierarchical model. It is found that the proportion of floating population with short-term and long-term residence intention is more than 60%, indicating that amphibious and multi-habitat livelihood is still the dominant livelihood strategy of floating population; there is an obvious spatial difference between short-term and permanent residence willingness. The short-term residence willingness is the highest in the eastern region and the lowest in the northeast region, while the permanent residence willingness shows a completely opposite distribution pattern; the floating population in the central and western regions has the highest willingness to stay for a long time. The results of the model show that the inflow characteristics and the individual characteristics of the floating population jointly affect different types of residence intention: in the eastern and central regions, economically developed areas and areas with high average wages, the floating population has higher short-term and long-term residence intention and lower permanent residence intention; the floating population who are male with agricultural registered permanent residence, low-level of education and family average monthly income, short floating time and inter provincial mobility tend to stay for a short time and a long time; the floating population who are female with non-agricultural registered permanent residence, high-level of education and family average monthly income, moving within the province and outside the province for a long time are more willing to settle permanently in the inflow place.
Dissertations / Theses on the topic "Average residence time"
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Novak, Jeffrey. "A COMPARATIVE ANALYSIS OF DIFFERENCES IN RESIDENT SATISFACTION, RETENTION, AND CUMULATIVE GRADE POINT AVERAGE BETWEEN UNIVERSITY." Doctoral diss., University of Central Florida, 2008. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/2303.
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This study compared students' perceptions and satisfaction as they related to their place of residence. In addition, this study sought to determine if a difference existed between student retention rates from their first year in college to their second year and one's grade point average with respect to one's place of residence within the collegiate setting. As such, the problem this study examined was the overall impact of where a first-time-in-college student lived within the University of Central Florida housing system and how that living environment impacted students' levels of satisfaction, overall retention rates, and cumulative grade point averages. The data used for this study were obtained from a previously distributed survey conducted by the Department of Housing and Residence Life at the University of Central Florida in February 2007. Secondary data were obtained through the Department of Institutional Research at the University of Central Florida. A website link to an optional, self-administered Internet-based survey was sent via email to University of Central Florida students residing in university owned housing and university affiliated housing. The size of the sample was determined by the number of delivered emails 3800 for university owned housing, 1,500 for university affiliated housing (Towers), and 1,831 for university affiliated housing (Pegasus Landing). Of the total populations: 1) 38.57 percent were returned for university owned housing, 2) 26.26 percent were returned for university affiliated (Towers at Golden Knights Plaza), and 3) 24.63 percent were returned for university affiliated housing (Pegasus Landing). There were many statistically significant relationships. Consistently, students residing in university owned housing showed higher satisfaction and agreement levels when compared with students living in university affiliated housing. Additionally, students living in university owned housing showed a higher retention rate and cumulative grade point average when compared with students living in university affiliated housing.<br>Ed.D.<br>Department of Educational Research, Technology and Leadership<br>Education<br>Educational Leadership EdD
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Heukelman, Sean. "Introducing micro-pelletized zinc concentrates into the Zincor fluidized solid roasters." Diss., University of Pretoria, 2009. http://hdl.handle.net/2263/27477.
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Zincor, a refinery in South Africa, uses the conventional roast-leachelectrowinning process to produce zinc metal. The roasting process of ZnS concentrate makes use of four Lurgi fluidized bed roasters to produce calcine (contains ZnO and ZnFe2O4 as zinc products) and SO2 gas. The roasting plant consists of two 18 m2 and two 35 m2 cross sectional area roasters. Prior to 1996, Zincor utilized air as the only oxidant and fluidizing medium in its roasters. The maximum dry feed rates that the roasters could process were 6.5 t/d.m2. In an attempt to increase production, oxygen enrichment was first trialled and then introduced into the fluidizing air. The ability of oxygen enrichment to increase the rate of the ZnS oxidation reaction allowed higher feed rates to the roasters. This was successful and oxygen enrichment was permanently implemented. That enabled dry feed rates to be maintained at 7.0 t/d.m2 and 7.3 t/d.m2 for the small and big roasters respectively. Oxygen enrichment up to 26% in the fluidizing air is utilized. Due to the highly competitive nature of the zinc industry, innovative processing techniques are necessary to be competitive. The aim of this study is to determine whether oxygen enriched air can be reduced by introducing micro-pelletized concentrate into the roaster feed blend, whilst maintaining current roaster feed rates and calcine quality. This study was executed in four parts. Firstly, the role entrainment played in influencing average particle residence time. Secondly, a study of production methods for stable micro-pellets. Thirdly, a study of the influence of oxygen enrichment and particle size on the roasting of micropellets. The fourth part of the study was introduction of micro-pellets into the Zincor roasters to determine whether oxygen enrichment could be reduced. The particle size distribution of a blend of feed concentrate to the roasters is 50% passing approximately 48 μm. This leads to entrainment values between 87% and 91%. The micro-pelletization process reduces the –500 μm fraction from 87% to 10%, which degrades to 30% during roasting. This requires that approximately 48% of the concentrate needs to be micro-pelletized to restore the 70% designed entrainment target. It was determined that entrained particles spend on average 0.46 hr to 2.44 hr in the bed compared to particles in the overflow that have residence times between 3.93 and 4.00 hr. The calculated times for entrainable particles are somewhat higher and for the bed overflow lower compared to the values measured by Spira, 1970. The required reaction time for micropellets was found to be far below their residence time inside a Zincor roaster. With a load of 20% micro-pellets introduced into the feed concentrate, the oxygen enrichment could be reduced by 60%. The quality of the calcine produced was maintained above the target of 98.8% ZnS to ZnO conversion. The results of this study have shown that the use of micro-pelletization of concentrate at Zincor reduces entrainment of particles successfully. Manipulation of entrainment through micro-pelletization can be used successfully to reduce oxygen enrichment, whilst improving production and maintaining quality at Zincor. Copyright<br>Dissertation (MEng)--University of Pretoria, 2010.<br>Materials Science and Metallurgical Engineering<br>unrestricted
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Miyata, Yoshiki, та 佳樹 宮田. "琵琶湖の炭素源への石灰岩地帯の寄与". 名古屋大学年代測定資料研究センター, 2013. http://hdl.handle.net/2237/20181.
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Musner, Tommaso. "Transport Processes and Optimization Strategies in Wetland Design." Doctoral thesis, Università degli studi di Padova, 2013. http://hdl.handle.net/11577/3423098.
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Transitional areas, between inland and coastal environments, represent an important habitat for their environmental and natural value. They act as a natural buffer for all those chemicals which are produced by diffused sources of pollutants (run-off rain water from agriculture) or from hidden sources (sewers not connected to a wastewater treatment plant). Pollutants produced by this type of sources can lead, if not conveniently treated, to eutrophication and to other water quality problems along coastal areas. Traditional wastewater treatment methods appear to be not effective in these conditions because of the big volumes of water and the relatively low concentration of dissolved pollutants to be treated. Since traditional wastewater treatment plants can not be used, it becomes important to better understand transport phenomena in transitional environments (rivers and wetlands) and all the removal processes in such zones in order to manage them to treat all the chemicals before they arrive to the coastal areas. Particular attention must be therefore stressed on retention processes and on the formulation of predictive models which allow scientists and engineers to better manage and design these buffer areas.
In Chapter 1, the role of different transport processes is analyzed focusing the attention on different spatial and temporal scales. Principal modeling approaches are discussed underlining the role of each term on the mass balance equation and the most classical model closures are described in this chapter.
In Chapter 2, retention characteristics of three different rivers are analyzed, relating different model closures with planimetric features of the rivers, their vegetational cover and bottom permeability. The analysis is carried on using STIR (Solute Transport In Rivers) model, a one-dimensional solute transport model that describes concentration breakthrough curves implementing a wide set of retention phenomena characterized by different time scales, represented by a specific residence time distribution in each retention domain. Comparison of modeling results and experimental data shows the capability of the model to characterize, with an inverse analysis, retention processes that occur in a river.
In Chapter 3 a two-dimensional schematic wetland is studied with a numerical model that solves, with a shallow water approach, hydrodynamic and mass transport equations. A specific processing of the numerical results is used to determine numerical residence time distributions of the wetland as a function of a particular vegetation distribution that reproduces a central channel delimited by two lateral, more densely vegetated, banks. To each different density ratio it corresponds a specific shape of the residence time distribution, that present a clear bimodality below a critical value. To model this specific phenomenon, typical in natural environments, a simple and a more easy to use one-dimensional model approach is implemented in the former STIR model. The new version is called STIR-DTD.
In Chapter 4 a new innovative optimization approach to wetland design is defined. Numerical solution of a two-dimensional shallow water model using the open-source suite TELEMAC2D, is integrated with an evolutionary optimization algorithm. At the initial stage of the evolution strategy, the removal efficiency of a random population of individuals (each individual represents a specific distribution of vegetated patches over the wetland domain) is evaluated numerically solving a shallow water hydrodynamic model coupled with a solute transport model. Once the removal efficiency is known, the evolutionary algorithm, using a wide range of selection operators that mimic natural evolution, evolve the initial population to an individual that maximizes the pollutant mass removal. Performed tests show how the optimized distribution tends to cover the maximum wetland available area or, if a maximum vegetated area is kept fixed, how the distribution tends to lengthen the flow paths between the inlet and the outlet section of the wetland.
Chapter 5 shows results of a preliminary analysis on the removal efficiency of randomly distributed vegetation characterized by a Gaussian spatial probability density function. Vegetation density is treated as a random variable characterized by a mean, a variance and an homogeneous correlation length. The effect of each distribution on the removal efficiency is numerically evaluated by a coupled hydrodynamic and solute transport that accounts for the pollutant decay. Results show how removal efficiency is correlated with the statistical parameters of the space probability density function used to generate the random filed.<br>Le zone di transizione tra entroterra e mare costituiscono una porzione di territorio molto importante dal punto di vista ambientale e naturalistico. Esse rappresentano un naturale filtro per tutte quelle specie chimiche che sono prodotte da fonti di inquinamento diffuse (dilavamento di suoli agricoli) o occulte (scarichi non collettati o irregolari) che possono creare, se non opportunamente trattate, problemi di eutrofizzazione e di qualità delle acque lungo le coste. I tradizionali metodi di depurazione si rivelano poco efficaci nel trattare questo tipo di effluenti, per le grandi portate da gestire e per le relativamente basse concentrazioni di inquinanti. Risulta importante quindi, nell'impossibilità di impiegare i tradizionali impianti di depurazione, comprendere le dinamiche di trasporto negli ambienti naturali (fiumi e aree umide) e i meccanismi di rimozione degli inquinanti in tali zone, in modo da poterle utilizzare per riassorbire, in modo sostenibile e naturale, il carico di inquinanti che altrimenti raggiungerebbe direttamente le coste. A questo scopo è necessario focalizzare l'attenzione sui processi di ritenzione e sulla formulazione di appropriati strumenti modellistici che consentano ai tecnici e ai modellisti una comprensione sufficientemente ampia dei fenomeni e forniscano loro degli strumenti pratici che aiutino nella gestione e riprogettazione di queste aree tampone.
Nel Capitolo 1 viene analizzato il ruolo di differenti processi di trasporto focalizzando l'attenzione su diverse scale spaziali e temporali di analisi e descrivendo i principali approcci modellistici utilizzati per trattare ciascun fenomeno. E' evidenziato il contributo di ciascun termine al bilancio di massa e sono prese in considerazione le chiusure modellistiche più classiche oggi adottate.
Nel Capitolo 2 si analizzano le caratteristiche dei processi di ritenzione in tre diversi corsi d'acqua mettendo in relazione le diverse chiusure modellistiche adottate in funzione delle caratteristiche planimetriche degli alvei, della loro composizione vegetazionale e delle caratteristiche di permeabilità del fondo. L'analisi \'e eseguita utilizzando il modello di trasporto monodimensionale STIR (Solute Transport In Rivers) che si presta a descrivere le curve di concentrazione implementando una vasta gamma di fenomeni di ritenzione a diverse scale temporali, descritte da specifiche distribuzioni dei tempi di residenza del soluto in ciascun comparto di ritenzione. L'accordo dei dati sperimentali con le curve di concentrazione mostra come si possa, tramite analisi inversa, caratterizzare un fiume dal punto di vista della ritenzione.
Il Capitolo 3 prende in considerazione un'area umida bidimensionale di cui si risolvono, con un approccio modellistico alle acque basse, l'idrodinamica e il trasporto di massa. Una opportuna procedura di analisi dei risultati numerici è utilizzata per determinare le distribuzioni dei tempi di residenza dell'area umida in funzione di una particolare distribuzione di vegetazione che riproduce un canale principale delimitato da due zone laterali a maggiore densità di vegetazione. A diversi rapporti di densità corrisponde una specifica forma della distribuzione che presenta, al di sotto di uno specifico valore di soglia, una evidente bimodalità. Per rappresentare opportunamente tale fenomeno, comune negli ambienti naturali, con un approccio modellistico mono-dimensionale di più semplice utilizzo, è proposta in questo capitolo, una nuova versione del modello STIR denominata STIR-DTD.
Il Capitolo 4 presenta un approccio innovativo di ottimizzazione alla progettazione di un'area umida. La risoluzione numerica di un modello bidimensionale alle acque basse tramite il modello TELEMAC2D è integrata infatti con un algoritmo evolutivo di ottimizzazione. Allo stadio iniziale dell'evoluzione, è definita, in modo casuale, una popolazione di individui (ciascun individuo rappresenta una specifica distribuzione di zone vegetate) di cui il modello valuta l'efficienza depurativa. A partire dal livello di efficienza depurativa dimostrata da ciascuna distribuzione, l'algoritmo evolutivo, tramite specifici operatori genetici che mimano i processi di selezione naturali, evolve la popolazione verso la distribuzione di vegetazione che massimizza l'abbattimento di inquinanti. I test effettuati mostrano come la distribuzione ottimale evolva verso configurazioni che tendono a coprire tutta l'area vegetata disponibile o, qualora questa sia fissata, a prolungare il più possibile i percorsi di flusso all'interno delle aree vegetate.
Il Capitolo 5 riporta i risultati di una prima analisi eseguita su campi random di vegetazione, descritti da una opportuna funzione densità di probabilità spaziale (Gaussiana). La risoluzione tramite un modello bidimensionale accoppiato ad uno di trasporto e decadimento mostra come l'efficienza depurativa e la portata siano correlabili con i parametri (densità media, varianza e lunghezza di correlazione) che caratterizzano la particolare distribuzione statistica di vegetazione adottata.
Books on the topic "Average residence time"
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Snyder, Sean. The Average Time It Takes a Tokyo Resident to Reach a Convenience Store. Delano Greenridge Editions, 2003.
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Seetharam Sridhar, Kala. Indian Cities or Suburbs? Oxford University PressOxford, 2025. https://doi.org/10.1093/9780198958147.001.0001.
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Abstract This book answers research questions regarding the suburbanization of persons, households, and jobs in India’s cities, their regional variations, factors which associate with this sprawl, and their consequences. We use granular data from the Global Human Settlements Layer (GHSL) at the sub-kilometre grid level for 100 Indian cities. We find that the downward-sloping population density function is appropriate for studying India’s cities. Next, we find India’s population was significantly more suburban (82%) than urban (33%) in 2015. We find that cities in the south Indian and urbanized states are more sprawling when compared with cities across all India, for 2015. Those in the slow-growing states are relatively more compact. We find that employment is more decentralized than population suburbanization in 2015. We find that, on average, half of all jobs are concentrated in a 5-km compass of the city core. Jobs in urban areas of the southern and the metropolitanized states are more suburbanized relative to cities in the slow-growing states and those in the entire country, for 2011. We find the time-lagged value of the 1975 population gradient has a powerful association with the 2015 gradient and changes in the density gradient over 1975–2015, and that poor central city economic conditions push residents away to the suburbs. We find negative effects of sprawl on the environment and the delivery of basic services, such as water supply, healthcare and education, and air quality.
Book chapters on the topic "Average residence time"
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Franco, Renan Louro Cardoso, Carsten Eichert, Charlotte Lücking, Lars Biermann, Mandy Paschetag, and Stephan Scholl. "revolPET®: An Innovative “Back-to-Monomer” Recycling Technology for the Open Loop Value Chain of PET and Polyester Composite Packaging and Textiles." In Lecture Notes in Mechanical Engineering. Springer International Publishing, 2023. http://dx.doi.org/10.1007/978-3-031-28839-5_20.
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AbstractNowadays there is a need for innovative solutions for composite materials in the packaging and textile sectors. These are formed by multilayer structures that improve technical performance however complicates recycling. Consequently, they are mostly sent to energy recovery or downgrade recycling processes. To avoid this, new recycling technologies are needed.The innovative “back-to-monomer” recycling technology “revolPET®” represents a solution for this challenge. In the process, the polyethylene terephthalate (PET) is selectively depolymerized to recover the monomers ethylene glycol (EG) and terephthalic acid (TA) for a new PET production. By an alkaline hydrolysis, the PET reacts continuously with a strong base in a twin-screw extruder. The average residence time in the extruder is less than one minute with a process yield up to 95%. Due to the mild depolymerization conditions, the other polymers remain chemically unchanged and can be easily separated. The produced monomers are regained in virgin quality and can achieve a 33% reduction on the greenhouse gases emissions if compared with the crude oil production route.In this contribution, the technology on a pilot scale as well as the results of the first scale-up investigations are presented and discussed with respect to technical maturity and environmental benefit.
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Flores-Bastidas, Lizbeth, Juan Lata-García, Sandro C. S. Jucá, and Gary Ampuño. "Sustainable Energy in Ecuador and Latin America: A Review of the Energy Landscape of the Type of Renewable Sources." In Lecture Notes in Networks and Systems. Springer Nature Switzerland, 2025. https://doi.org/10.1007/978-3-031-87065-1_29.
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Abstract The development of a region is closely related to the consumption of electrical energy as long as the generation is able to meet the needs of industry, commerce and residence. This paper reviews the production, consumption of traditional energy and especially renewable generation in Latin America, detailing the energy trend in recent years in Ecuador. On the other hand, it shows the general overview of the development of renewable energies, such as hydroelectric, biomass, wind, solar, and biogas in the South American country. The figures show that the renewable energy installed in the country went from 20,382.76 GWh in 2010 to 37,036.70 in 2024, while generation from renewable sources went from 43.54% to 73.19% in the same period of time. Non-conventional renewable energies have not had an expected growth as is the case of solar despite the abundant solar resource that on average global insolation is 4,575 Wh/m2/day, in 2010 the installed solar and wind power went from 0.02 MW and 2.4 MW to 29.06 MW and 71.13 MW respectively. Another of the main findings is the decrease in post-pandemic energy consumption in Latin America, in 2017 consumption was 2477,207 GWh of which 55.7% comes from renewable sources while in 2021 consumption was 1637,868 GWh corresponding to 58.97 from renewable sources. The document opens other lines of research as proposals for the legislation that regulates renewable energies in Ecuador, from distributed generation for the self-supply of regulated consumers to the methodology for the term and prices of generation and self-generation projects.
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Long, Yu, Juanlin Fu, Li Yan, Minghong Yu, Xuanyan Li, and Yuzhen Liu. "Health Risk Assessment of Park Environment Based on Particulate Matter (PM2.5) - A Case Study of Mianyang City." In Lecture Notes in Civil Engineering. Springer Nature Singapore, 2024. http://dx.doi.org/10.1007/978-981-97-8401-1_46.
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AbstractAir pollution seriously harms human health, especially the fine particulate matter (PM2.5) in pollutants is more harmful to the human body. Urban parks are important public places for residents’ activities, and the air quality of the park's micro-environment directly affects residents’ respiratory health. This article uses the method of field measurement, takes the People's Park of Mianyang City as the research object, conducts PM2.5 monitoring and statistical analysis of crowd activities under light to moderate pollution weather, and according to the visit frequency, conducts health risk assessment of important spaces. The research results show: 1. The daily average PM2.5 concentration in People's Park is high, and there are obvious differences in spatial and temporal distribution. 2. There is some overlap between the peak period of people flow in People's Park and the time period when the daily PM2.5 concentration is high. 3. There is a high health risk in the space nodes where the activities of some people in the People's Park are highly concentrated. This article uses the principle of crowd exposure assessment to construct a health risk assessment method for parks, analyze the potential health risks of the spatial environment of People's Park, and provide new guidance for people to choose healthy activity places and urban public space renewal and optimization, which has certain practical significance.
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Hipp, John R., and Jae Hong Kim. "Income Inequality and Economic Segregation in Los Angeles from 1980 to 2010." In The Urban Book Series. Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-64569-4_19.
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AbstractRising income inequality is a critical problem in both the global North and South. In the United States, the Gini coefficient measuring nationwide income inequality rose from 0.403 in 1980 to 0.480 in 2014 (US Census), and residential segregation by income has increasingly occurred in many metropolitan regions and is particularly reflected in the spatial separation of the wealthiest households. This chapter focuses on the change in the level of income inequality in the Los Angeles region since 1980 and how it is related to changes in residential segregation between economic groups over that same time period. We use data from the US Census collected in 1980, 1990, 2000, and 2010. We measure residential segregation between economic groups based on occupational structure, and measure ‘neighbourhoods’ using Census tracts: these are units defined by the US Census and typically average about 4,000 residents. The overall level of inequality in the region is measured at each decade point using the Gini coefficient for household income. Maps demonstrate where different socioeconomic status groups have tended to locate and how economic segregation has changed in Los Angeles over this time period. We also assess the extent to which changes in inequality are related to changes in economic segregation over the last four and a half decades.
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Procaccini, Giulia, and Carol Monticelli. "Building Façade Retrofit: A Comparison Between Current Methodologies and Innovative Membranes Strategies for Overcoming the Existing Retrofit Constraints." In The Urban Book Series. Springer International Publishing, 2023. http://dx.doi.org/10.1007/978-3-031-29515-7_66.
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AbstractThe constant expansion of the cities outside their borders, together with the rapid growth of new technologies and the environmental impact of the building sector, make existing buildings quickly obsolete, both in terms of their functions and their performances. Achieving the goal for greenhouse gas reduction by 2030 implies the necessity to improve the energy performances of the building stock and, for doing so, to overcome the existing constraints that very often prevent builders, tenants and residents from undergoing a renovation process. Given also that the building renovation contributes in the up-cycle strategy of the building stock, avoiding the production of unnecessary waste caused by demolition processes, innovative fast and average costly solutions must be shaped in order to encourage building façade renovation processes at different scales of interventions. Considering that membranes present some inherent properties (such as lightness, thinness, fast assembly, etc.) that make them suitable for both temporary and permanent façade renovations and valuable for overcoming current retrofit constraints, their investigation is of primary interest in order to promote and achieve an extensive building façade renovation. Starting by the investigation of Textile-based Façade Retrofit Solutions (TFRS), this analysis aims at comparing current methodologies with innovative membranes retrofit strategies, in order to evaluate the effectiveness and advantages of textile-based products in overcoming existing constraints to façade retrofit. The main goal of the analysis is to present innovative membrane existing solutions for making building façades resilient and adaptable to the several requirements expected from time to time. The research highlights future developments for TFRS with regard to both temporary and permanent solutions through their employment over existing façades.
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Abdelwahed, Nadia, Salem Al Asousi, Faryal Iqbal, et al. "Gastric Cancer in the UAE." In Cancer Care in the United Arab Emirates. Springer Nature Singapore, 2024. http://dx.doi.org/10.1007/978-981-99-6794-0_28.
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AbstractThis review reports the current status of gastric cancer (GC) in the United Arab Emirates (UAE) population. The incidence in the Emirati population is lower than in other nationalities, with 30 patients versus 104 cases from non-UAE residents. Gastric cancer ranks as the fifth malignancy causing deaths in the UAE, with an estimated average of 4.31% of cancer deaths compared to global rates. Gastric cancer in the UAE is considered less lethal. The GC’s crude incidence rate in the UAE in 2021 was 1.4 per 100,000, which is lower than the global incidence crude rate. Gastric cancer has a high mortality rate in the UAE due to the advanced stage at the time of presentation compared to early-stage gastric cancer, with the majority (30 cases) in 2017 presenting with the advanced disease at diagnosis compared to 12 cases with the early stage. Fifty-five percent of gastric cancer in the UAE in 2017 was classified as being in an unknown stage, indicating the need for better medical documentation of the data provided by each patient in order to get proper staging of all cancers, including gastric cancer.Medical and surgical management of gastric cancer in the UAE is advanced and in keeping with best international practices. Robotic surgeries, novel anticancer therapies, including chemotherapy and immunotherapies, and targeted therapies are all available in the UAE.The relationship between risk factors in the country and gastric cancer incidence should be thoroughly studied to try to identify high-risk populations. More research is also needed to investigate and identify the factors that may be contributing to the observed, potentially higher incidence of gastric cancer in younger patients.
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Peters, A. M., and M. J. Myers. "Transit time, clearance, distribution volume and extraction fraction." In Physiological Measurements with Radionuclides in Clinical Practice. Oxford University PressNew York, NY, 1998. http://dx.doi.org/10.1093/oso/9780192619945.003.0002.
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Abstract One of the major attributes of nuclear medicine is its ability to quantify physiological processes, and to do so non-invasively. The most important physiological variables in nuclear medicine are: through a discrete space (its ‘mean transit time’) or the average time it spends in a space (its ‘mean residence time’). Some physiological variables are expressed as a transit or residence time (for example, perfusion in units of ml/min/ml) or as combinations of time with volume, giving flow rate (ml/min), or time with mass, giving a flux rate (mg/min).
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"Biology, Management, and Protection of North American Sturgeon." In Biology, Management, and Protection of North American Sturgeon, edited by Douglas W. Cooke, Steven D. Leach, and J. Jeffery Isely. American Fisheries Society, 2002. http://dx.doi.org/10.47886/9781888569360.ch9.
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<em>Abstract.</em>—Shortnose sturgeon <em>Acipenser brevirostrum</em> have been reported in Cooper River, South Carolina, and upstream of it’s hydroelectric dam and navigation lock in the Santee-Cooper lake system. The navigation lock has been used for decades to pass anadromous Alosa spp. upstream, but use of the lock by shortnose sturgeon to pass the dam has been undetected. We studied the effectiveness of the lock to pass shortnose sturgeon and the behavior of shortnose sturgeon in the tailrace of the hydroelectric facility over a five-year period. Fixed station radio telemetry was used to record movement of 48 shortnose sturgeon with internally-implanted transmitters and 24 shortnose sturgeon with externally-attached transmitters. Shortnose sturgeon tended to congregate in a small area approximately 100 m downstream of the dam. Residence time in the tailrace averaged 30.1 d after being released. Fifty percent of the tagged fish returned the following year, but residence time was much shorter (×= 13.0 d) with 65% of these fish staying less than five days. Eighty-three percent of internally tagged fish entered the lock, with individual fish entering an average of 7.4 times. However, none passed from the lock into the upstream lake.
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Kong, Ki-Sik, Sung-Ju Roh, and Chong-Sun Hwang. "A Study on the Performance of IPv6-Based Mobility Protocols." In Mobile Computing. IGI Global, 2009. http://dx.doi.org/10.4018/978-1-60566-054-7.ch224.
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The performance of IP mobility protocols is highly dependent on the change of mobile nodes’ (MNs’) mobility and traffic-related characteristics. Therefore, it is essential to investigate the effects of these characteristics and to conduct an in-depth performance study of these protocols. In this paper, we introduce a novel analytical approach using a continuous-time Markov chain model and hierarchical network model for the performance analysis of IPv6 mobility protocols: Mobile IPv6 (MIPv6) and Hierarchical Mobile IPv6 (HMIPv6). According to these analytical models, we derive the location update costs (i.e., binding update costs plus binding renewal costs), packet tunneling costs, and total signaling costs, which are generated by an MN during its average domain residence time, when MIPv6 or HMIPv6 is deployed under the same network architecture, respectively. In addition, based on these derived costs, we investigate the effects of various parameters, such as the average speed of an MN, binding lifetime period, the ratio of the network scale, and packet arrival rate, on the signaling costs generated by an MN under MIPv6 and HMIPv6. Moreover, we conduct the performance comparison between these two protocols by showing the relative total signaling costs under the various conditions. The analytical results show that as the average speed of an MN gets higher and the binding lifetime period is set to the larger value or as its packet arrival rate gets lower, the total signaling cost generated by an MN during its average domain residence time under HMIPv6 will get relatively lower than that under MIPv6, and that under the reverse conditions, the total signaling cost under MIPv6 will get relatively lower than that under HMIPv6.
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Russo, Natasha Greice Moreira, Thalia Delgado Bezerra, Ivity Nicoleti Simonis, et al. "USE OF MICROREACTORS FOR SYNTHESIS OF DIABETES DRUGS." In Science and Connections: The Interdependence of Disciplines. Seven Editora, 2025. https://doi.org/10.56238/sevened2024.037-147.
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The fraction of the world population affected by type 2 diabetes mellitus and its tendency to increase significantly in the coming decades strongly encourages improvements in the synthesis of drugs for glycemic control. The transfer of batch production to continuous processes in microreactors allows for reduced synthesis time and better yield. In this article, four microreactor designs were proposed — maze, sheet, honeycomb, and serpentine with honeycomb — to enable the synthesis of drugs in a single microreactor with a volume greater than 1 mL. The mixing quality of the prototypes was evaluated by simulating their residence time distributions (RTDs) through computational fluid dynamics (CFD). The RTDs were obtained as a response to the step of a methylene blue-like tracer and maintaining a spatial time of 20 min. In the sheet, honeycomb, and serpentine with honeycomb designs, preferential flow paths were formed, evidenced by the structure of the velocity field and the average residence time of less than 20 min. Their fluid dynamics behaviors were hybrids between the ideal models of a piston flow reactor and a perfectly stirred mixing tank. The labyrinth design has a pressure drop seven times higher than the others because it allocates all the fluid in a single long channel, but it promoted mixing of the streams with the greatest homogeneity in the available volume and with a deviation of 0.36% between the mean residence time and the spatial time, being the most promising design for drug synthesis among those proposed.
Conference papers on the topic "Average residence time"
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Li, Genong, Aniruddha Mukhopadhyay, Chi-Yang Cheng, and Yi Dai. "Various Approaches to Compute Fluid Residence Time in Mixing Systems." In ASME 2010 3rd Joint US-European Fluids Engineering Summer Meeting collocated with 8th International Conference on Nanochannels, Microchannels, and Minichannels. ASMEDC, 2010. http://dx.doi.org/10.1115/fedsm-icnmm2010-30771.
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Residence time including mean residence time and residence time distribution (RTD) is a very important parameter to characterize a mixing system. In practice, tracer study has been widely used in experiments to obtain residence time distribution. There are several numerical approaches available to compute the average residence time and the residence time distribution of a system. This paper attempts to summarize those available approaches through an example.
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Rodrigo, A. J. S., J. P. B. Mota, and E. Saatdjian. "Chaotic Mixing in Time-Periodic 3-D Flows." In ASME 2002 Joint U.S.-European Fluids Engineering Division Conference. ASMEDC, 2002. http://dx.doi.org/10.1115/fedsm2002-31365.
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Mixing in a special class of three-dimensional, non-inertial time-periodic flows is studied quantitatively. In the type of flow considered here, the cross-sectional velocity components are independent of the axial flow which is assumed to be fully developed. Using the eccentric helical annular mixer as a prototype, the time-periodic flow field is induced by adding a sinusoidal component to the rotation speed of the inner cylinder. For a given 3-D mixer geometry, the degree of mixing achieved is a function of two parameters that measure the strength of the cross-sectional stirring protocol relative to the mean residence time of the fluid in the mixer: the average number of turns of the outer cylinder, and the average number of modulation periods. We find that for a given mixer geometry and mean residence time, there is an optimum modulation frequency for which the standard deviation of the temperature field at the exit is a minimum.
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Elmalky, Adham M., and Mohamad T. Araji. "A Novel Genetic Algorithm for Optimizing Microalgae Residence Time in Flat Panel Photobioreactors." In International Conference on Mechanical, Automotive and Mechatronics Engineering. ECER, 2023. http://dx.doi.org/10.53375/icmame.2023.264.
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Microalgae photobioreactors often rely on proper adjustment of residence time, which is a key variable for maximizing thermal and bioenergy generation. Limiting the residence time to a constant value over long periods can reduce the overall system productivity. The aim of this study was to investigate the performance of a new operational strategy for flat panel photobioreactors when integrated into building façades. This was achieved by examining the impact of variable residence time on biomass production and carbon absorption. The study coupled a detailed chemical kinetics model with Genetic Algorithm in the presence of shading assessment. The chemical model validation showed an average error of 3.8%. Different selection techniques were examined for the employed Genetic Algorithm framework to decrease the computational cost. The feasibility of the optimized photobioreactor was further assessed based on reducing the operational carbon footprint when added to building façades. Results showed that the optimal hourly residence times varied between 0.91 days and 1.97 days with an average value of 1.05 days. This increased the daily biomass generation by 28.8%, from 13.9 g/m2 to 17.9 g/m2. Corresponding CO2 extraction was also increased from 31.4 g/m2 to 34.8 g/m2. On annual basis, integrating the photobioreactors into building façades decreased the operational carbon footprint by 10 kgCO2/m2, 50 kgCO2/m2, and 140 kgCO2/m2 for low-rise, mid-rise, and high-rise buildings, respectively.
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Eilers, Benn, Vinod Narayanan, Sourabh Apte, and John Schmitt. "Steam-Methane Reforming in a Microchannel Under Constant and Variable Axial Surface Temperature Profiles." In ASME/JSME 2011 8th Thermal Engineering Joint Conference. ASMEDC, 2011. http://dx.doi.org/10.1115/ajtec2011-44390.
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An experimental study of steam methane reforming in a microchannel is presented. Palladium nanoparticles, deposited on a porous aluminized FeCrAlY felt, served as catalyst sites for the reforming reactions. Parametric studies of steam-methane ratio, residence time, average reactor temperature, and temperature distribution were performed. Results demonstrated in excess 60 percent conversion of methane at an average reactor temperature of 900°C and the lowest experimented residence time of 26 milliseconds. Methane conversion was found to be strongly dependent on reactor temperature. Ramping temperature distributions demonstrated a 46 percent greater hydrogen output than isothermal reactions performed at the same average temperature.
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Beerer, David, Vincent McDonell, Scott Samuelsen, and Leonard Angello. "Interpretation of Flow Reactor Based Ignition Delay Measurements." In ASME Turbo Expo 2009: Power for Land, Sea, and Air. ASMEDC, 2009. http://dx.doi.org/10.1115/gt2009-60268.
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Compositional variation of global gas supplies is becoming a growing concern. Both the range and rate-of-change of this variation is expected to increase as global markets for Liquefied Natural Gas (LNG) continue to expand. Greater fuel composition variation poses increased operational risk to gas turbine engines employing lean premixed combustion systems. Information on ignition delay at high pressure and intermediate temperatures is valuable for lean premixed gas turbine design. In order to avoid autoignition of the fuel/air mixture within the premixer, the ignition delay time must be greater than the residence time. Evaluating the residence time is not a straight forward task because of the complex aerodynamics due to recirculation zones, separation regions, and boundary layers effects which may create regions where the local residence times may be longer than the bulk or average residence time. Additionally, reliable experiments on ignition delay at gas turbine conditions are difficult to conduct. Devices for testing include shock tubes, rapid compression machine and flow reactors. In a flow reactor ignition delay data are commonly determined by measuring the distance from the fuel injector to the reaction front (L) and dividing it by the bulk or average flow velocity (U) under steady flow conditions to obtain a bulk residence time which is assumed to be equal to the ignition delay time. However this method is susceptible to the same boundary layer effects or recirculation zones found in premixers. An alternative method for obtaining ignition delay data in a flow reactor is presented herein, where ignition delay times are obtained by measuring the time difference between fuel injection and ignition using high speed instrumentation. Ignition delay times for methane, ethane and propane at gas turbine conditions were in the range of 40–500 ms. The results obtained show excellent agreement with recently proposed chemical mechanisms for hydrocarbons at low temperature/high pressure conditions.
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Ruiz, Janneth, Antonio Ardila, Bernardo Rueda, et al. "A Proposed Procedure for Identifying the Predominant Heat Transfer Modes Along the Length of Large Nickel Laterite Ore Rotary Kiln: Experimental Validation in an Industrial Process." In ASME 2021 Heat Transfer Summer Conference collocated with the ASME 2021 15th International Conference on Energy Sustainability. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/ht2021-64016.
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Abstract Nickel is essential in many consumer, industrial, military, transport, aerospace, marine, and architectural products due to its outstanding physical and chemical properties. This work focuses on the calcination and pre-reduction of laterite nickel ore to produce ferronickel. Ferronickel is an alloy containing nickel (about 30% wt.) and iron used for manufacturing stainless steel. Calcination and pre-reduction entail removing chemically bonded water from partially dried ore and removing oxygen from mineral oxides in the calcine. Here we combine a proprietary database with operation data of two rotary kilns and model predictions of Mean Residence Time, shell losses, intraparticle evaporation, and intraparticle temperature distribution. The kilns feature notable differences in length, inclination angle, excess air, but the predicted Mean Residence Times are similar. A fitted profile of experimental solids bed temperature represented particles surface temperature. The model considered slab-like mineral particles with surface-to-center distances of 13, 25, and 38 mm. Results show notable differences in the drying zone length and average surface-to-center temperature differences. Surface-to-center distances higher than 25 mm result in average surface-to-center temperature differences higher than 80°C. The following steps are improvements in the particle model and its coupling with the gas and wall temperature profiles.
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Haley, David B., and Vinod Narayanan. "Performance Characterization of a Microscale Hydrogen Combustor Recuperator and Oil Heat Exchanger." In ASME 2011 International Mechanical Engineering Congress and Exposition. ASMEDC, 2011. http://dx.doi.org/10.1115/imece2011-64176.
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Experiments on a novel design of a microscale hydrogen combustor heat exchanger (μCHX) are presented. The experimental study demonstrates proof of concept for the design and examines the effect of varying selected fluidic and geometric conditions on the overall efficiency of the μCHX. A unit cell consisting of a combustion channel, a recuperator channel and an oil heat exchange channel is tested. This unit cell device has the potential to be scaled up to a reactor in the tens of kilowatts range required for practical heating applications. Combusted gases flow back through the device in a cross-flow configuration between the combustion channel and the oil channel, preheating the inlet gas stream and transferring heat to the oil. Platinum has been selectively deposited on the stainless steel inner wall of the combustion channel to facilitate heterogeneous combustion of hydrogen and air. The performance of the μCHX is characterized based on a global efficiency, defined as the ratio of the energy transferred to the oil stream compared to the energy rate of the supplied hydrogen gas. The effects of residence time, equivalence ratio, and average oil temperature, have been investigated. Hydrogen conversion rates in excess of 95 percent were achieved for residence times between 20–25 ms. Efficiencies in excess of 90 percent were obtained for equivalence ratios greater than 0.5 and for average oil temperatures between 63 °C and 105 °C. Experiments were also performed on two different lengths of catalyst with a higher efficiency being demonstrated by the catalyst with the longer length.
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Guo, Rong, and Yo Cui. "Urban regeneration and sustainable urban development from polycentric spatial structure traffic performance." In Post-Oil City Planning for Urban Green Deals Virtual Congress. ISOCARP, 2020. http://dx.doi.org/10.47472/cpqc8140.
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Traffic congestion has become the main phenomenon of agglomeration dis-economy in urban. Adjusting spatial structure to improve traffic efficiency and reduce traffic pollution has become an important issue of urban sustainable development. The study adopts the social survey method to test the traffic performance of Harbin polycentric spatial structure. Combine with the colocation hypothesis, the paper analyzes the influencing factors of polycentric commuting distance and commuting time. The results show that the average commuting distance of centers is greater than that in the city, and the proportion of long-distance commuting is higher, but the faster commuting speed in the fringe area subcenters makes average commuting time shorter than that in the city. The importance of commuting costs is insufficient, the employment and residential location resources are extremely unbalanced, and they influence location selection of residence and employment and makes long-distance commuting economically reasonable. The fundamental ways to improve the traffic performance of polycentric spatial structure are to face up to the rationality of long-distance commuting and traffic demand, in urban renewal, adjusting commuting cost and the spatial layout of residential and employment resources, improving the balance between occupation and housing, promoting sustainable urban development.
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Ozalp, Nesrin, and D. JayaKrishna. "Numerical Study on the Thermal Interaction of Gas-Particle Transport for a Vortex Flow Solar Reactor." In ASME 2010 4th International Conference on Energy Sustainability. ASMEDC, 2010. http://dx.doi.org/10.1115/es2010-90325.
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Solar reactors, by nature of their high temperature, are nearly experimentally inaccessible. Most instruments capable of measuring fluid flow cannot survive the harsh temperatures inside the reactor. As such, computational fluid dynamics (CFD) has been relied on to provide insight into the flow within the reactor. Because of the size of the computing resources necessary to properly account for all of the physical mechanisms within the solar reactor, the current state of numerical simulations only provide a limited level of insight. The present study provides an analysis of flow behavior and thermal interaction of gas-particle flow for a directly irradiated vortex flow solar reactor. The thermal hydraulics between gas flow and particle has been considered by two way coupled Euler-Lagrange approach. A two band discrete ordinate (DO) model has been considered to solve radiative transport between walls and entrained particles. The effect of main flow, secondary flow, particle loading, particle diameter and residence time are studied to analyze flow physics and heat transfer. Results are presented in terms of static temperature contours, temperature distribution along the center line of the cavity, path lines and particle temperature. It is observed that with the increase in main flow, secondary flow and particle diameter average outlet temperature of the fluid increases, and with the increase in particle loading the outlet temperature decreases. The particle exit temperature is observed to increase with the increase in residence time.
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Wang, Zhonghao, Bin Hu, Qingjun Zhao, and Jianzhong Xu. "Towards Predicting Lean Blow-Off Based on Damköhler Number and Practical Reaction Zone." In ASME Turbo Expo 2017: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/gt2017-63507.
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Lean Blow-off (LBO) is important in gas turbine combustion. In this paper, numerical simulation and experiment are conducted to develop a new method for LBO prediction of gas turbine combustors based on Damköhler (Da) number and practical reaction zone (PRZ). PRZ is established based on OH concentration in the reacting flow of combustor, and it is simplified to a perfectly stirred reactor (PSR) due to the drastic mixing caused by swirling flow. Flow time scale (Ft) and chemical time scale (Ct) contained in Da number are all specified based on PRZ. Flow time scale (Ft) is defined as the residence time of fuel flowing through the PRZ, and chemical time scale (Ct) is defined as the shortest time needed to trigger the chemical reaction in PRZ. Da numbers, which introduce the physical competition between Ft and Ct, are calculated under LBO conditions and design point. The average Da number at LBO is about 1, ranging from 0.6 to 1.86, and the Da number of design condition is 4.33, showing that the method proposed in the paper is reliable and has the potential for practical engineering applications.
Reports on the topic "Average residence time"
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Azzi, Elias S., Cecilia Sundberg, Helena Söderqvist, Tom Källgren, Harald Cederlund, and Haichao Li. Guidelines for estimation of biochar durability : Background report. Department of Energy and Technology, Swedish University of Agricultural Sciences, 2023. http://dx.doi.org/10.54612/a.lkbuavb9qc.
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Biochar is produced by heating biomass in the total or partial absence of oxygen. This report addresses the long-term persistence of biochar in soil and how this can be managed in climate calculations and reporting. The report consists of this summary and four chapters, which can be read independently. Different terms have been used to describe the durability of biochar carbon storage, but also the physical presence of biochar in soils, e.g. persistence, permanence, recalcitrance, residence times, stability. Today, the term “durability of carbon storage” is preferred in policy contexts, but various academic disciplines such as soil science have other established terms like “persistence”. Here, both durability and persistence are used, rather interchangeably. It is important to be aware of differences in meaning that exist between disciplines. The purpose of this report is to present the state of knowledge regarding the proportion of carbon in biochar that remains in the soil over time and provide recommendations for calculating this. There is a need to calculate the persistence of biochar in soil for national climate reporting, corporate climate reporting, carbon credit trading, and life cycle assessments for various purposes. On the persistence of biochar The amount of biochar remaining after a certain time depends on the properties of the biochar and the environment in which it is located. Nearly all research on biochar persistence has focused on its application in agricultural soils. The main reason for the high durability of biochar carbon storage is the formation of fused aromatic stable structures during biomass pyrolysis. A high degree of fused aromatic structures makes biochar much less prone to microbial decomposition than fresh biomass. Different biochars have different properties, and this influences how long they persist in the soil. To achieve biochar with properties that provide higher persistence, it should be produced at higher temperatures for a sufficient duration. Measuring and calculating biochar persistence Established quantification methods of 100-year biochar persistence (e.g. referenced in IPCC inventory guidelines and used in voluntary carbon markets, to date) extrapolate short-term soil decomposition processes, and do not fully consider the processes that may explain millennial persistence. Calculations regarding biochar persistence have traditionally used a time span of 100 years to describe the amount of remaining carbon after a certain time. The use of specifically 100 years lacks a well founded scientific reason, but has been regarded as “far enough” into the future from a climate perspective and close enough for modelling to be meaningful. An active area of research relevant for the understanding biochar carbon storage durability is the development of advanced analytical characterisation methods of biochar that will enable measurement of the physicochemical heterogeneity in carbon structures present in biochar. Another area of continued research is biochar incubation, with a focus on field conditions, to elucidate both differences from laboratory conditions, and how transport processes affect biochar in the field. Recommendation and conclusion In the project, available research data has been aggregated into a functional model that calculates how much of the carbon in biochar remains after a given number of years. The model is based on the H/C ratio of the biochar placed in the soil and the annual average temperature at the location. The model is made freely accessible to provide biochar market actors with the best available knowledge for estimating the durability of biochar carbon. Existing research results provide a sufficient foundation for estimation of the amount of biochar expected to remain over time. Future research results are expected to lead to increased knowledge regarding the decomposition properties of biochar, in particular biochars with a very low H/C ratio. Therefore, this recommendation will be revised by the end of the project in 2025.
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Gavin, Greg, Paul Inkenbrandt, Trevor Schlossnagle, and Rebecca Molinari. Groundwater of Pahvant Valley, Millard County, Utah. Utah Geological Survey, 2024. http://dx.doi.org/10.34191/ss-173.
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Pahvant Valley, located in Millard County, Utah, encompasses 1610 square miles and includes several small towns, agricultural districts, hot springs, and biologically important wetlands, all heavily reliant on groundwater. This study, conducted by the Utah Geological Survey during 2022 and 2023, aims to define Pahvant Valley’s water recharge and discharge estimates, characterize its primary hydrogeologic units, and describe groundwater recharge and discharge areas. The research includes the collection of groundwater and surface water samples to estimate flow paths, sources of recharge and discharge, and residence times. Additionally, a water-level campaign was conducted in early March 2022 to create an updated potentiometric surface map for the region. Pahvant Valley’s groundwater system comprises three main aquifers: the valley-fill aquifer, the volcanic aquifer of the Tabernacle Hill and Ice Springs lava flows, and the Black Rock Desert volcanics. For this study, we delineated these aquifers into three conceptual groundwater zones based on hydrogeologic, geochemical, and potentiometric characteristics. Results of this study indicate significant groundwater level declines, particularly in agricultural areas, driven by overextraction and reduced recharge. Groundwater levels have declined by an average of 26 feet since 1986 and some areas have experienced declines of up to 160 feet. The study emphasizes the crucial role of streamflow from the Pahvant Range in recharging the valley-fill aquifer, with stable isotope and chemical analyses confirming that stream discharge significantly contributes to groundwater recharge. Additionally, groundwater quality varies across the valley and increased total dissolved solids could affect water usability in some areas. The analysis of irrigation practices reveals a significant shift in the early 1990s from flood irrigation to pivot irrigation, which led to increased and more consistent crop density and health, as indicated by Normalized Difference Vegetation Index (NDVI) data. From 1992 to 2021, NDVI values rose substantially in both magnitude and duration, reflecting higher crop yields over time. This increase in crop density and vitality resulted in higher evapotranspiration per acre, while the extended duration of greenness demonstrated stable yields regardless of surface water availability. As irrigation shifted from surface water to groundwater sources, numerous high-capacity wells were established to meet demand. Consequently, groundwater pumping in areas no longer reliant on surface water led to declines in groundwater elevations. These decreases in groundwater levels have been linked to land subsidence, with Interferometric Synthetic Aperture Radar (InSAR) analysis detecting up to 5 inches of ground deformation in the Meadow area between 2014 and 2022, closely associated with changes in groundwater levels. This study underscores the critical balance between groundwater extraction and recharge, the effects of irrigation practices on water use, and the importance of continuous monitoring and management to ensure sustainable groundwater resources. The findings highlight the need for sustainable groundwater management practices to maintain agricultural productivity and ecological health in Pahvant Valley.
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Westrick-Payne, Krista. Grandparents’ Characteristics by Age, 2022. National Center for Family and Marriage Research, 2024. http://dx.doi.org/10.25035/ncfmr/fp-24-20.
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The average age of grandparents in the U.S. in 2022 was 68 years. Grandparenthood is more common among older adults (aged 65 and older) than those in midlife (aged 40-64). In 2022, the percentage of older adults who were grandparents (67%) was more than 2.5 times greater than the percentage among those in midlife (24%). Data from the 2023 panel of the Survey of Income and Program Participation (SIPP) are used to update Wu, 2018 & Westrick-Payne, 2023 comparing midlife grandparents to those at older ages across demographic characteristics in 2022. The SIPP is a nationally representative household-based survey that directly asks respondents if they are a grandparent, making it one of the few national surveys that identify non-resident grandparents. This profile is number three in our 2024 series on grandparents in the U.S.
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Wood, McLeod. Finding Asymmetry During Mobilisation in the Australian Army. Australian Army Research Centre, 2025. https://doi.org/10.61451/2675145.
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The mobilisation of national economies, industries and armed forces for war has long been a complex problem. Mobilisation brings a range of issues that both government officials and military staffs must navigate to be successful; it is no easy task. As great power competition increases across the globe, and the likelihood of conflict in the region rises, the Australian Army should consider the ways in which it might find competitive asymmetry if it were to be mobilised in defence of Australia. This paper seeks to demonstrate that Army’s capacity to weather previous national mobilisation events has been supported by a body of trained personnel delivering ‘just in time’ mobilisation effects. As Army prepares for all future scenarios, it must acknowledge the depth, and latent skill, held within its ranks and within society that will support mobilisation efforts. Where once the Army called upon personnel with a mere 30 days’ training per year, it can now draw upon personnel with an average of 10 years’ experience. It is the depth and quality of professional training resident within Army’s workforce, and society, that will give Australia an asymmetric advantage over its adversaries during conflict.
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DiGrande, Laura, Sue Pedrazzani, Elizabeth Kinyara, et al. Field Interviewer– Administered Dietary Recalls in Participants’ Homes: A Feasibility Study Using the US Department of Agriculture’s Automated Multiple-Pass Method. RTI Press, 2021. http://dx.doi.org/10.3768/rtipress.2021.mr.0045.2105.
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Objective: The purpose of this study was to assess the feasibility of administering the Automated Multiple-Pass Method (AMPM), a widely used tool for collecting 24-hour dietary recalls, in participants’ homes by field interviewers. Design: The design included computer-assisted personal interviews led by either a nutritionist (standard) or field interviewer. Portion estimators tested were a set of three-dimensional food models (standard), a two-dimensional food model booklet, or a tablet with digital images rendered via augmented reality. Setting: Residences in central North Carolina. Participants: English-speaking adults. Pregnant women and individuals who were fasting were excluded. Results: Among 133 interviews, most took place in living rooms (52%) or kitchens (22%). Mean interview time was 40 minutes (range 13–90), with no difference by interviewer type or portion estimator, although timing for nutritionist-led interviews declined significantly over the study period. Forty-five percent of participants referenced items from their homes to facilitate recall and portion estimation. Data entry and post-interview coding was evaluated and determined to be consistent with requirements for the National Health and Nutrition Examination Survey. Values for the number of food items consumed, food groups, energy intake (average of 3,011 kcal for men and 2,105 kcal for women), and key nutrients were determined to be plausible and within reasonably expected ranges regardless of interviewer type or portion estimator used. Conclusions: AMPM dietary recall interviews conducted in the home are feasible and may be preferable to clinical administration because of comfort and the opportunity for participants to access home items for recall. AMPMs administered by field interviewers using the food model booklet produced credible nutrition data that was comparable to AMPMs administered by nutritionists. Training field interviewers in dietary recall and conducting home interviews may be sensible choices for nutrition studies when response rates and cost are concerns.
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Rawling, Geoff C. Winter 2019�2020 Water-Level Elevation Map for the Albuquerque Metropolitan Area. New Mexico Bureau of Geology and Mineral Resources, 2023. http://dx.doi.org/10.58799/ofr-622.
Full textAbstract:
Residents of the Albuquerque metropolitan area rely in part on groundwater for domestic, municipal, and industrial use. An understanding of changes in groundwater levels and groundwater storage changes in the aquifer is necessary to achieve groundwater management goals set by the Albuquerque Bernalillo County Water Utility Authority (2016), henceforth the Water Authority. Periodic and continuous water-level measurements in wells and maps of the water-level elevation surface, or water table, derived from these data are essential tools for understanding the groundwater resources of the region.This report describes the preparation and interpretation of a water-table map for the Albuquerque area for the winter of 2019-2020. Water-level changes and changes in the amount of groundwater in storage in the aquifer since the predevelopment time period are presented. Predevelopment is defined by the map of Bexfield and Anderholm (2000; Fig. 1) and represents conditions prior to 1961. The present study also recasts recent water-level surface and changes since predevelopment in terms of water-level management criteria defined by the Water Authority (2016), shown in the block diagram in Figure 2. Referring to this diagram, the range of water-level elevations from 50 ft of drawdown to 250 ft of drawdown relative to predevelopment conditions is defined as the working reserve. The fuel gauge on the diagram pertains to the water level relative to the base of the working reserve, the 250-ft drawdown level. The 50 ft of aquifer below the working reserve is referred to as the safety reserve. The base of the safety reserve, at 300 ft of drawdown relative to predevelopment, is a conservative estimate of when irreversible compaction effects will start to be felt in the aquifer. The diagram also shows the management level of 110 ft of drawdown, which is a target average value drawdown for wells used by the Water Authority.
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Traumatic Brain Injury: Inpatient Hospitalizations, Observation Stays, and Emergency Department Discharges, Massachusetts Residents, FFY 2016-FFY 2018. Brain Injury Association of Massachusetts (BIA-MA), 2023. http://dx.doi.org/10.58912/avve3026.
Full textAbstract:
Traumatic brain injury (TBI) is the most common type of acquired brain injury (ABI), and a major cause of death and disability. The Centers for Disease Control and Prevention (CDC) estimates the annual incidence of TBI to be 2.87 million in the United States. To estimate the magnitude of this health problem in Massachusetts, the statewide inpatient hospital, outpatient observation stays, and emergency department discharge databases were analyzed by the Massachusetts Department of Public Health (MADPH) in 2014 for the years 2008-2010, as part of a comprehensive epidemiological study of acquired brain injury in Massachusetts. The consensus definition for traumatic brain injury specified by the CDC and in use at the time was utilized (i.e., ICD-9-CM: International Classification of Diseases-9-Clinical Modification diagnostic codes for TBI). Since then, the consensus definition utilized for traumatic brain injury surveillance purposes was revised utilizing the ICD-10-CM diagnostic codes. Updated epidemiological data regarding TBI in Massachusetts, requested by the Brain Injury Association of Massachusetts (BIA-MA) and provided by the Massachusetts Department of Public Health, are summarized in the attached report for federal fiscal years (FFY) 2016-2018. The average annual count for TBI-related hospital stays was 8,831, and the average annual count for emergency department (ED) visits associated with a discharge diagnosis of traumatic brain injury was nearly 63,000 for the time period studied. The most common mechanism of injury was unintentional fall, accounting for 67% of TBI-related inpatient stays and approximately 51% of emergency department visits. The highest number and rate of hospital stays for TBI were among residents 70 years of age and older, who also had the second highest rate and number for TBI-related ED visits. Children 0-2 years of age had the highest rate for TBI-related ED visits.