Academic literature on the topic 'Leader discharge'
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Journal articles on the topic "Leader discharge"
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Rakov, V. A., M. D. Tran, Y. Zhu, Z. Ding, A. F. R. Leal, I. Kereszy, and S. Chen. "New insights into the lightning discharge processes." Plasma Sources Science and Technology 31, no. 10 (October 1, 2022): 104005. http://dx.doi.org/10.1088/1361-6595/ac9330.
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Abstract This review covers selected results of recent observations of lightning discharges performed across the entire electromagnetic spectrum (radiofrequency, optical, and energetic radiation) at the Lightning Observatory in Gainesville, Florida. The most important results include (a) characterization of the preliminary-breakdown, stepped-leader, and return-stroke processes in high-intensity (⩾50 kA) negative lightning discharges, (b) the first high-speed video images of bidirectional leader that made contact with the ground and produced a return stroke, (c) discovery of negative stepped leader branches colliding with the lateral surface of neighboring branches of the same leader, (d) new data on the occurrence context and properties of compact intracloud discharges, and (e) observation of a terrestrial gamma-ray flash that occurred during a bipolar cloud-to-ground lightning discharge. The results serve to improve our understanding of the physics of lightning with important implications for lightning modeling, lightning protection, and high-energy atmospheric physics studies.
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Das, Sayantan, and Udaya Kumar. "Modeling of Bi-Polar Leader Inception and Propagation from Flying Aircraft Prior to a Lightning Strike." Atmosphere 13, no. 6 (June 9, 2022): 943. http://dx.doi.org/10.3390/atmos13060943.
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Lightning is one of the major environmental threats to aircraft. The lightning strikes during flying are mostly attributed to aircraft-triggered lightning. The first step toward designing suitable protective measures against lightning is identifying the attachment locations. For this purpose, oversimplified approaches are currently employed, which do not represent the associated discharge phenomena. Therefore, in this work, a suitable model is developed for simulating the inception and propagation of bi-polar leader discharge from the aircraft. Modeling of leader discharges requires field computation around the aircraft, which is carried out employing the Surface Charge Simulation Method (SCSM) combined with sub-modeling, which ensures the best accuracy of field computations near nosecone, wingtips, etc. A DC10 aircraft model is considered for the simulation. Simulations are performed for different pairs of leader inception points on aircraft using the developed model. Subsequently, corresponding ambient fields required for stable bi-polar discharge from aircraft are determined. These values are in the range of measured ambient fields reported in the literature. In summary, the present work has come up with a suitable model for simulating the bi-polar leader inception and propagation from the flying aircraft. Using the same, a detailed quantitative description of the discharge phenomena from the aircraft is provided.
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Ma, Xinyu, Chijie Zhuang, Zezhong Wang, and Rong Zeng. "Positive Leader Velocity and Discharge Current Considering Leader Branching Under Different Air Pressures." IEEE Transactions on Plasma Science 47, no. 5 (May 2019): 1939–43. http://dx.doi.org/10.1109/tps.2018.2886570.
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Belosheev, V. P. "Discharge leader self-organization on the water surface." Technical Physics 45, no. 7 (July 2000): 922–27. http://dx.doi.org/10.1134/1.1259749.
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Xie, Yaoheng, Yue Yishi, Huisheng Ye, Liu Yun, Yongheng Zhong, and Xiangeng Zhao. "The development characteristics of the discontinuous leader under the positive switching impulse with low rate of voltage rising." European Physical Journal Applied Physics 83, no. 2 (August 2018): 20802. http://dx.doi.org/10.1051/epjap/2018180103.
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Discontinuous leader development is the most important discharge process under the application of the switching impulse voltage with the low rate of voltage rising, which is of great significance to study the external insulation characteristics of ultra-high voltage (UHV) large scale air gap. Based on the CMOS high-speed camera, a discharge test with different operating impulse voltage is carried out by constructing a comprehensive observation platform of rod-plate air gap discharge, and a clear discontinuous leader development process picture is captured. Moreover, the leader current, injection charge and leader channel unit length charge, and their characteristics of the change trend are also obtained. Further analysis based on the experimental results shows that the discontinuous leader development under the action of the impulse voltage with low rate of voltage rising has two different laws. Finally, this paper uses the thermodynamic equation, combined with the test results, the channel temperature changes in the discontinuous leader development stagnation stage were calculated. The results show that the leader channel temperature is still greater than 1500 K in the hundreds of microsecond time scales in the leader stagnation stage, and the subsequent leader can continue to develop on the original leader channel.
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Qie, X., Y. Yu, C. Guo, P. Laroche, G. Zhang, and Q. Zhang. "Some features of stepped and dart-stepped leaders near the ground in natural negative cloud-to-ground lightning discharges." Annales Geophysicae 20, no. 6 (June 30, 2002): 863–70. http://dx.doi.org/10.5194/angeo-20-863-2002.
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Abstract. Characteristics of the electric fields produced by stepped and dart-stepped leaders 200 µs just prior to the return strokes during natural negative cloud-to-ground (CG) lightning discharges have been analyzed by using data from a broad-band slow antenna system with 0.08 µs time resolution in southeastern China. It has been found that the electric field changes between the last stepped leader and the first return stroke could be classified in three categories. The first type is characterized by a small pulse superimposed on the abrupt beginning of the return stroke, and accounts for 42% of all the cases. The second type accounts for 33.3% and is characterized by relatively smooth electric field changes between the last leader pulse and the following return stroke. The third type accounts for 24.7%, and is characterized by small pulses between the last recognizable leader pulse and the following return stroke. On the average, the time interval between the successive leader pulses prior to the first return strokes and subsequent return strokes was 15.8 µs and 9.4 µs, respectively. The distribution of time intervals between successive stepped leader pulses is quite similar to Gaussian distribution while that for dart-stepped leader pulses is more similar to a log-normal distribution. Other discharge features, such as the average time interval between the last leader step and the first return stroke peak, the ratio of the last leader pulse peak to that of the return stroke amplitude are also discussed in the paper.Key words. Meteology and atmospheric dynamics (atmospheric electricity; lightning) – Radio science (electromagnetic noise and interference)
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Cooray, Vernon, Hasupama Jayasinghe, Marcos Rubinstein, and Farhad Rachidi. "The Geometry and Charge of the Streamer Bursts Generated by Lightning Rods under the Influence of High Electric Fields." Atmosphere 13, no. 12 (December 2, 2022): 2028. http://dx.doi.org/10.3390/atmos13122028.
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The streamer bursts generated during the initiation and propagation of leaders play an important role in the creation and maintenance of hot discharge channels in air. The most important parameters related to streamer bursts in this respect are the length of the streamer bursts, their lateral extent and the charge associated with them. The lateral extent of the streamer bursts may play a significant role in deciding the path and the tortuosity of the discharge channels of laboratory discharges and lightning. The charges associated with the streamer bursts are needed in understanding the physical processes associated with the streamer-to-leader transition. In this paper, the length, the lateral extension and the charge of the streamer regions generated by grounded conductors when exposed to external electric fields are estimated. This estimation is based on two assumptions: (i) once a streamer is incepted, the streamer head follows the direction of maximum background electric field at the location of the streamer head and (ii) the streamer continues to extend along this direction until the potential drop along the streamer channel matches the potential drop caused by the background electric field between the initial and end points of the streamer channel. The same technique could be used to estimate the streamer bursts generated in laboratory discharges and lightning stepped leaders. It is shown that in estimating the geometry of the streamer region, it is necessary to include the spread of streamers caused by branching. Moreover, the charge associated with the streamer region increases as the frequency of branching increases. The results obtained confirm that the charge in the streamer region can significantly change the potential ahead of the streamer region from the background potential and this has to be taken into account in any study that simulates the initiation and propagation of lightning leaders. Since the streamer bursts of leaders control the direction and speed of the leaders, the technique we have used here could be implemented in lightning leader progression models.
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Keffer, C. W. "Waste Discharge Reduction Program Overview – Monsanto Agricultural Company." Water Science and Technology 24, no. 12 (December 1, 1991): 29–32. http://dx.doi.org/10.2166/wst.1991.0367.
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Monsanto is committed to being a leader in reducing waste discharges to the environment. The Company announced in June 1988 a commitment to reduce air emissions of hazardous materials by 90% by the end of 1992. In addition, Monsanto Agricultural Company established a further goal to reduce the discharge of organic and hazardous inorganic materials to all environmental media. Projects have been identified for the Agricultural Company to achieve the 90% air emission reduction goal and to reduce projected 1995 waste discharges from 150 million pounds to 50 million pounds.
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Pei, Zhehao, Weijiang Chen, Xing Fan, Jianwei Gu, Shengxin Huang, Xiaosong Liu, Zhong Fu, et al. "The contribution of femtosecond laser filaments to positive and negative breakdown discharge in a long air gap." Physics of Plasmas 30, no. 4 (April 2023): 043511. http://dx.doi.org/10.1063/5.0138646.
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Discharges of different polarities develop in different modes, resulting in different guiding effects by femtosecond laser filaments. Knowledge of the contribution of laser filaments to positive and negative discharges is the basis of the laser-guided long-air-gap discharge technique. This study presents a direct comparison of the inception, propagation, and breakdown characteristics of discharges of both polarities. Long-air-gap discharge experiments under the switching impulses of both polarities are carried out under the same experimental conditions. Discharge modes and phases are also considered. The statistical results show that positive discharge inception voltages are transformed from a Weibull distribution into an exponential distribution under the influence of laser filaments, but there is little effect on the negative discharge inception voltage. The guidance probability of a positive discharge reaches 15% at most during the dark period stage, leading to little effect on the breakdown discharge probability. However, for negative discharges, the guidance probability can exceed 95%. An investigation of the filament contributions to both polarity discharges shows that the different migration directions of photoelectrons lead to a difference in the effects of laser filaments on inception voltages, and the difference in the connection of the two discharge passages leads to a difference in the guidance probability. Through the results of a simulation model, it is speculated that the connection condition for positive discharges is that the positive leader overlaps with the laser filaments, and, for negative discharges, the rod electrode is connected to the laser filaments through bi-directional discharge propagation.
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Molas, Michał, and Marcin Szewczyk. "Experimental Evaluation of 3D Tortuosity of Long Laboratory Spark Trajectory for Sphere-Sphere and Sphere-Plane Discharges under Lightning and Switching Impulse Voltages." Energies 14, no. 21 (November 7, 2021): 7409. http://dx.doi.org/10.3390/en14217409.
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Evaluation of attractive areas of high- and ultra-high voltage power transmission lines to direct lightning strokes is based on modeling of propagating progress of the lightning leader approaching the transmission line. The aim of the modeling is to determine the effectiveness of lightning protection for a given line design. The statistical models are currently being developed to extend the conventional deterministic models by embracing the randomness of the discharge channel in space and hence to reproduce the statistical distribution of the striking points. These models require experimental data for understanding of the lightning leader development process and to validate the model across the measurement data. This paper reports on the measured trajectories of discharge channels of long laboratory sparks in various high voltage laboratory arrangements. The sparks were initiated by switching and lightning impulses with peak values ranging from 1200 kV to 3364 kV of positive and negative polarity for two types of high-voltage electrode systems (sphere-sphere and sphere-plane), arranged at distances of 3.3 m and 5.5 m from each other. Statistical distributions of angles describing trajectory of discharge channels in space are reported for a total number of 540 recorded discharges. The results can serve as reference measurement data to develop and evaluate the accuracy of simulation models incorporating statistical nature of the lightning leader development process.
Dissertations / Theses on the topic "Leader discharge"
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Arevalo, Liliana. "Numerical Simulations of Long Spark and Lightning Attachment." Doctoral thesis, Uppsala universitet, Elektricitetslära, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-149171.
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The research work presented here is concerned with numerical simulations of two different electrical phenomena: Long gap electrical discharges under switching impulses and the lightning attachment process associated with positive upward leaders. The development of positive upward leaders and the progression of discharges in long gaps are attributable to two intertwined physical phenomena, namely, the leader channel and the streamer zone. The physical description and the proposed calculations of the above-mentioned phenomena are based on experimental tests conducted in long spark gaps. The methodology presented here proposes a new geometrical approximation for the representation of the streamer and the calculation of the accumulated electrical charge. Furthermore, two different approaches to representing the leader channel are applied and compared. Statistical delays before the inception of the first corona, and random distributions to represent the tortuous nature of the path taken by the leader channel were included based on the behavior observed in experimental tests, with the intention of ensuring the discharge behaved in a realistic manner. A reasonable agreement was found between the physical model and the experimental test results. A model is proposed to simulate the negative discharges produced by switching impulses using the methodology developed to simulate positive leader discharges and the physics underlying the negative leader phenomena. The validation of the method demonstrated that phenomena such as the pilot leader and negative leader currents are successfully represented. In addition, based on previous work conducted on the physics of lightning and the lightning attachment process, a new methodology is developed and tested. In this new approach, the background electric field and the ionized region, considered in conjunction with the advance of the leader segment, are computed using a novel method. The proposed methodology was employed to test two engineering methods that are accepted in international standards, the mesh method and the electro-geometrical method. The results demonstrated that the engineering approximations are consistent with the physical approach. In addition to the electrical phenomena mentioned above, one should remember that, to simplify the calculation, there are certain real effects arising from the lightning attachment process that have not been considered. In fact, when a structure is subjected to a strong electric field, it is possible to generate multiple upward leaders from that structure. This effect has not been taken into account in the numerical models available previously, and therefore the process of generating multiple upward leaders incepted over a structure is incorporated here. The results have shown that a slight advantage from the background electric field is enough for one upward connecting leader to take over, thereby forcing the others to abort the attachment process.
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Liu, Lipeng. "Physics of Electrical Discharge Transitions in Air." Doctoral thesis, KTH, Elektroteknisk teori och konstruktion, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-205401.
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Electrical discharges with a variety of different forms (streamers, glow corona, leaders, etc.) broadly exist in nature and in industrial applications. Under certain conditions, one electrical discharge can be transformed into another form. This thesis is aimed to develop and use numerical simulation models in order to provide a better physical understanding of two of such transitions, namely the glow-to-streamer and the streamer-to-leader transitions in air. In the first part, the thesis includes the two-dimensional simulation of the glow-to-streamer transition under a fast changing background electric field. The simulation is performed with a fluid model taking into account electrons. An efficient semi-Lagrangian algorithm is proposed to solve the convection-dominated continuity equations present in the model. The condition required for the glow-to-streamer transition is evaluated and discussed. In order to enable such simulations for configurations with large interelectrode gaps and long simulation times, an efficient simplified model for glow corona discharges and their transition into streamers is also proposed. The second part of the thesis is dedicated to investigate the dynamics of the streamer-to-leader transition in long air gaps at atmospheric pressure. The transition is studied with a one-dimensional thermo-hydrodynamic model and a detailed kinetic scheme for N2/O2/H2O mixtures. In order to evaluate the effect of humidity, the kinetic scheme includes the most important reactions with the H2O molecule and its derivatives. The analysis includes the simulation of the corresponding streamer bursts, dark periods and aborted leaders that may occur prior to the inception of a stable leader. The comparison between the proposed model and the widely-used model of Gallimberti is also presented.Elektriska urladdningar av olika former (streamers (från engelska), glöd-korona, ledare, etc.) förekommer i stor utsträckning i naturen och i industriella applikationer. Under vissa förhållanden kan en elektrisk urladdning omvandlas till en annan form av elektrisk urladdning. Denna avhandling syftar till att utveckla och använda numeriska simuleringsmodeller för att ge en bättre fysikalisk förståelse av två sådana övergångar, nämligen glöd-till-streamer- och streamer-till-ledar-övergångar, i luft. I den första delen, avhandlas en tvådimensionell simulering av glöd-till-streamer-övergången med ett hastigt föränderligt elektriskt fält i bakgrunden. Simuleringen utförs med en flödesmodell som tar hänsyn till elektronerna. En effektiv semi-Lagrangesk algoritm föreslås för att lösa de konvektionsdominerade kontinuitetsekvationerna i modellen. Vidare utvärderas och diskuteras förutsättningarna för glöd-till-streamer-övergången. För att möjliggöra sådana simuleringar i konfigurationer med stora elektrodavstånd och långa simuleringstider, föreslås också en effektiv och förenklad modell för glöd-korona-urladdningar samt deras övergång till streamers. Den andra delen av avhandlingen är tillägnad att undersöka dynamiken i streamer-till-ledar-övergångar över långa avstånd i luft, under atmosfäriskt tryck. Övergången studeras med en endimensionell termohydrodynamisk modell och en detaljerad kinetisk modell för blandningar av N2/O2/H2O. För att utvärdera effekten av luftfuktighet, innefattar den kinetiska modellen de viktigaste reaktionerna med H2O-molekylen och dess derivat. Analysen innefattar simuleringen av motsvarande streamer-kedjor, mörka perioder och avbrutna ledare som kan förekomma före starten av en stabil ledare. En jämförelse mellan den föreslagna modellen och den allmänt använda modellen av Gallimberti presenteras också.
QC 20170418
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Hayakawa, Naoki, Yuichiro Yoshitake, Naoto Koshino, Toshiaki Ueda, and Hitoshi Okubo. "Impulse partial discharge characteristics and their mechanisms under non-uniform electric field in N/sub 2//SF/sub 6/ gas mixtures." IEEE, 2005. http://hdl.handle.net/2237/6847.
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Diaz, Oscar. "Numerical modelling of positive electrical discharges in long air gaps." Doctoral thesis, Uppsala universitet, Elektricitetslära, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-298355.
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This dissertation deals with research on the numerical modelling of electrical discharges in laboratory long air gaps excited with positive switching impulses. It begins with the preliminary work of several scientists during the last decades, making a detailed analysis of different approaches for modelling all the stages in a full discharge. The relations between these models are identified as well as the effect on the outcome when modifying some important input parameters. The general concept describing the discharge phenomenon usually includes three main elements: the streamer inception, the streamer-to-leader transition and the stable leader propagation. These elements are present in many of the analysed models and the main differences between them are the assumptions and simplifications made by each author at a specific point in their methodologies. The models are usually simplified by assigning experimentally determined values to physical constants pertinent to different stages of the full discharge. These constants are the potential gradient in the leader-corona region to sustain the leader propagation, the charge per unit length along the leader channel which depends on the atmospheric conditions and the voltage impulse wave shape; and the leader propagation velocity, which is closely related to the discharge current. The dissertation includes the results of laboratory work related the study of leaders in long gap discharges, electrical parameters and optical records. By reconstructing the three-dimensional leader propagation for the rod-to-plane configuration, it was possible to study the random tortuous path followed by the leader as it propagates. One important element included in the discharge modelling is the representation of the leader-corona region in front of the leader tip as it propagates towards the grounded electrode. For the calculation of the net charge available in the leader-corona region, two new methodologies were pro-posed based on the electrostatic potential distribution obtained from a finite element method solver. This allowed the inclusion of more elements representing different parts of the discharge in the simulation domain. In the final part, all the analysed elements and the new proposed ones were included in a new methodology for the modelling of electrical dis-charges in long air laboratory gaps. The results obtained from this methodology were compared to experimental data. A good agreement was found between the simulation results and the experimental data.
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Konate, Lamine Boubacar. "Modélisation de la tenue diélectrique dans les grands intervalles d'air : application aux intervalles complexes." Thesis, Lyon, 2016. http://www.theses.fr/2016LYSEC040.
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Cette thèse est consacrée à l’étude de la décharge positive dans les grands intervalles d’air. L’objectif initial est de se doter d’un modèle capable de déterminer la tension U50 ainsi que le facteur d’intervalle k, deux facteurs importants entrant dans le dimensionnement des ouvrages hautes tensions, dans des géométries complexes. Pour ce faire un bilan des modèles de la décharge disponibles dans la littérature a été fait. Notre choix s’est porté sur le modèle de type circuit développé par le groupe du professeur Beroual et appliqué aussi bien à la décharge positive qu’à la décharge négative. Ce modèle est basé sur un schéma électrique équivalent, ses paramètres variant avec le temps en fonction des caractéristiques du canal et de la géométrie de la décharge. La propagation du leader est basée sur un critère lié au calcul du champ à sa tête et où le caractère aléatoire du trajet de la décharge est pris en compte. Comme la plupart des modèles présents dans la littérature, ce modèle ne s’intéresse qu’à l’intervalle de type pointe-plan. Une partie de ce travail a consisté à étendre le domaine d’applicabilité de ce modèle aux intervalles de géométrie complexes. Une étude détaillée de la géométrie pointe-pointe nous a permis de valider notre modèle dans sa capacité à simuler un exemple d’intervalle complexe. De plus, des essais expérimentaux nous ont permis de comparer la valeur de la U50 déterminée à l’aide de notre modèle et celle issue des expériences pour cette géométrie pointe-pointe. Les résultats obtenus sont en bon accord avec une marge d’erreur inférieure à 5%. Au vu du bon accord résultant de la confrontation modèle - expérience de laboratoire et de la grande similarité, grande étincelle - décharge atmosphérique, un modèle de foudre positif a été élaboré. Ce modèle nous a permis d’utiliser pour la première fois le modèle circuit pour modéliser le processus d’attachement de la foudre. Les résultats obtenues permettent de valider la faisabilité de trouver, aux méthodes standards de protection contre la foudre, une alternative numérique basé sur une simulation de la foudre. Une estimation du champ rayonné par le canal du leader a été effectuée. Ce qui ouvre une voie à l’étude de l’interaction de ces champs rayonnés avec les systèmes d’ingénierieThis thesis is devoted to the study of the positive discharge in large air gaps. The initial goal is to develop a model able to determine the voltage U50 and the k-factor, two important factors involved in the design of high voltage structures in complex geometries. To do this, a review of the discharge models available in the literature was done. We chose the circuit model developed by Professor Beroual’s group and applied to the positive discharge and also to the negative discharge. This model is based on an equivalent circuit diagram, his parameters varying with time according to the leader channel characteristics and the geometry of the discharge. The spread of the leader is based on a criterion related to the calculation of the field at its head and where the randomness of the discharge path is taken into account. As most of models found in the literature, this model applies only to the point-plane type interval. Part of this work was to extend the domain of applicability of this model to complex geometries. A detailed study of the rod-rod gap allowed us to validate our model in its ability to simulate an example of complex geometry. Moreover, experimental tests allowed us to compare the value of the U50 voltage determined using our model and the one from experiments for to this rod-rod geometry. The results are in good agreement with a margin of error of less than 5%. Given the good agreement resulting from the confrontation model - laboratory experience and the great similarity, large spark - atmospheric discharge, a positive lightning model was developed. This model allowed us to use for the first time the circuit model to model the lightning attachment process. The results obtained allow to validate the feasibility to find, to the standard methods of protection against lightning, digital alternative based on a simulation of lightning. An estimate of the field radiated by the leader channel was performed. This opens a way for the study of the interaction of these fields radiated with engineering systems
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Qi, Ling S. M. Massachusetts Institute of Technology. "Predicting department of medicine inpatients' discharges at US hospitals." Thesis, Massachusetts Institute of Technology, 2018. http://hdl.handle.net/1721.1/117962.
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Thesis: M.B.A., Massachusetts Institute of Technology, Sloan School of Management, in conjunction with the Leaders for Global Operations Program at MIT, 2018.Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, in conjunction with the Leaders for Global Operations Program at MIT, 2018.
Cataloged from PDF version of thesis.
Includes bibliographical references (page 67).
In the last few years, US hospitals have faced severe challenges with bed capacity management that leads to capacity congestion. Delivering patients to the right bed at the right time is very important to patient care quality. However, the current process employs a self-reporting system to receive bed availability from each unit. This method does not provide consistent estimates nor does it provide a standardized, proactive bed capacity management perspective. In addition, the Department of Medicine (DOM) has a very complex patient population, both clinically and non-clinically. Various team structure and uneven distributed bed resources introduce additional challenge on patient discharges. The project aims to develop a predictive analytics tool that consistently and reliably identifies potential patient discharges in the next 24 hours. The prediction tool allows hospitals to incorporate a more proactive bed capacity management process. Every day, a ranked list with each patient's likelihood to be discharged will be the output. This list guides a more focused conversation within the care team to make patient discharge decisions. In addition, the prediction tool provides a comprehensive summary of barriers to discharge. In this work, we extended the model developed by Zanger [9] for predicting surgical patients' discharges to medicine inpatients' discharge prediction. By partitioning the training and validation set by the date on 12/31/2017, the current performance for the full model on January 2018 medicine inpatients has a prediction power of - 0.74 (Area Under Curve of a Receiver Operating Characteristic curve - AUC ROC there onwards). We further evaluated the model performance for specific patient populations. With patients' Length-Of-Stay (LOS) up to 3 days, the model's performance in terms of AUC ROC can reach ~ 0.8; 0.78 for model with patients' LOS up to 5 days, 0.77 for model with patients' LOS up to 7 days, and 0.72 for model with patients' performance up to 12 days. In addition, the model can capture 57.8% discharges in the next 48 hours, and 33.1% discharges in the next 24 hours.
by Ling Qi.
M.B.A.
S.M.
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Zanger, Jonathan. "Predicting surgical inpatients' discharges at Massachusetts General Hospital." Thesis, Massachusetts Institute of Technology, 2018. http://hdl.handle.net/1721.1/117956.
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Thesis: M.B.A., Massachusetts Institute of Technology, Sloan School of Management, in conjunction with the Leaders for Global Operations Program at MIT, 2018.Thesis: S.M., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, in conjunction with the Leaders for Global Operations Program at MIT, 2018.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 121-124).
In the last few years, MGH has grappled with severe bed capacity management problems. As a result, delays occur in delivering the patient to the right bed at the right time, hindering patient care. One of the root causes for those delays is the mismatch between the timing of admissions and discharges. Particularly, while bed managers know about most admissions well in advance, there is a prevalent lack of central transparency regarding which patients might be ready to leave the hospital and what are the barriers that may delay their discharge. This project aims to improve MGHs bed management processes by introducing a predictive model (based on neural network) that identifies, in real time, surgical inpatients discharges that will occur in the next 24 hours. As part of this research, we present a new modeling methodology, formalizing concepts of 'Milestones to Post-Operative Recovery' and 'Barriers to Discharge', which systematically track patients progress towards discharge. For every admitted surgical patient, our solution outputs a score that is correlated with the likelihood for discharge within 24 hours, and derives a list of barriers to discharge ranked by their significance. In addition, the solution predicts with high accuracy (R-Square 0.86) the total number of daily surgical inpatient discharges, a key piece of information for bed managers. Given training population of 15,553 surgical inpatients admitted to MGH between May 2016 and August 2017, and test population (out-of-sample) of 1,151 surgical inpatients hospitalized during September 2017, the model achieved remarkable performance with ROC of 0.857. During non-holiday weekdays, among the top 10 ranked surgical inpatients identified by the algorithm to have the highest probability of being discharged, 90% were discharged within 24 hours and 97% were discharged within 48 hours, capturing 23% of the hospital's daily surgical discharges. Among the top 30 patients ranked by the algorithm, 69% were discharged within 24 hours and 89% were discharged within 48 hours, capturing 53% of the hospital's daily surgical discharges. The model was implemented as a web-based tool and is currently being piloted at MGH. Preliminary results show potential to promote proactive discharge processes to eliminate unnecessary delays. The implemented solution is using standard EMR data streams, and can be generalized across hospitals.
by Jonathan Zanger.
M.B.A.
S.M.
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Lynde, Stuart R. "Techniques for evaluating power plant discharges using in-situ leaf breakdown and flow-through laboratory sediment bioassays /." This resource online, 1994. http://scholar.lib.vt.edu/theses/available/etd-06102009-063152/.
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Becerra, Marley. "On the Attachment of Lightning Flashes to Grounded Structures." Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-8871.
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Lynde, Stuart R. "Techniques for Evaluating Power Plant Discharges Using In-Situ Breakdown and Flow Though Laboratory Sediment Bioassays." Thesis, Virginia Tech, 1994. http://hdl.handle.net/10919/36646.
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This research is divided into two main parts. Chapters 1 and 2 address the effect of thermal addition on the breakdown of Boxelder leaves (Acer negundo) in insitu and artificial stream studies. In both studies the rates for the decline in penetrance values decreased significantly in the thermally influenced treatments. Reduction in mass-loss rate coefficients was significant in the in-situ study, but not in the artificial streams. This result was due to differences in flow and macroinvertebrate colonization.
Chapters 3 and 4 address the development of a methodology for testing 24-48 hr old juvenile Asiatic clams (Corbicula fluminea) to sediments in 10-day bioassays. These organisms had acceptable survivorship in the controls (>70%), excellent recovery of all exposed organisms (97.5%) and were sensitive to copper-spiked sediments. Comparitive sensitivity of this age class demonstrated them to be equally or more sensitive than other commonly used sediment test organisms including Chironomus tentans, Daphnia magna and Hyalella azteca for survival and growth endpoints in 10-day exposures. Survival and growth effects for Corbicula juveniles were seen at 25 ppb copper in the sediment.Master of Science
Books on the topic "Leader discharge"
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MacKenzie, Judith-Anne. 10. The leasehold estate. Oxford University Press, 2016. http://dx.doi.org/10.1093/he/9780198748373.003.0010.
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Course-focused and comprehensive, the Textbook on series provide an accessible overview of the key areas on the law curriculum. This chapter considers the nature and characteristics of a lease, and the ways in which it is created and brought to an end. It discusses the basic requirements for a lease; the creation of leases; the disposition of leases and reversions; the determination of a lease; determination by discharge of contract; determination by joint tenants; ‘contractualisation’ of leases; the effect on subtenant of determination of head lease; and additional types of lease.
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Kachi, Toru. Shakuchi keiyaku kaijo no seito jiyu. Hatsubai Kindai Bungeisha, 1994.
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Petrucci, Giuseppe Antonio. The optogalvanic effect in a hollow cathode discharge: A resonance detector for very weak light levels. 1990.
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Ridley, Saxon. Recovering from critical illness in hospital. Oxford University Press, 2016. http://dx.doi.org/10.1093/med/9780199600830.003.0380.
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Recovery from critical illness may not be smooth and uneventful for the patient. Complications and adverse events may beset the patient and lead to intensive care unit (ICU) re-admission. Problems upsetting patients after discharge may be a manifestation of post-intensive care syndrome, new or recurrent organ failure. Avoiding post-ICU complications may be prevented by ensuring a well-planned transition from ICU to the general ward. This may be achieved by minimizing the impact and duration of organ support, defining a structured rehabilitation programme prior to ICU discharge. After discharge a short period spent on an intermediate care unit with higher nursing staff ratios, together with follow-up on the general ward will help identify and treat any new problems. Unfortunately, re-admission may be required to effectively treat some complications. There are recognized risk factors for ICU re-admission and these should be used to warn of the increased likelihood of adverse events to aid appropriate planning avoiding re-admission to ICU.
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Badiola, Ignacio, Tulsi Singh, Jiabin Liu, and Nabil Elkassabany. Acute Pain in the Opioid-Tolerant Patient. Oxford University Press, 2018. http://dx.doi.org/10.1093/med/9780190271787.003.0045.
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The number of people addicted to prescription and illicit opioids continues to increase, and many of these patients present to the hospital or pain center with acute pain issues. The matter is further complicated by the increasing number of patients with legitimately painful conditions treated with chronic opioid therapy. Typically, these patients are difficult to manage during any acute pain episode due to their opioid tolerance and opioid-induced hyperalgesia. This difficulty often leads to inadequate pain management, increased suffering, and delayed hospital discharge. Increased awareness is needed among pain management physicians and other clinicians who care for opioid-tolerant patients, yet there is a lack of evidence-based medicine regarding the optimal treatment of this population.
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Easdown, L. Jane. Muscle Weakness. Edited by Matthew D. McEvoy and Cory M. Furse. Oxford University Press, 2017. http://dx.doi.org/10.1093/med/9780190226459.003.0073.
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Muscle weakness in the perioperative period is a common finding and is a risk to patient safety. It can occur as a result of many physiological, pathological, and iatrogenic states. The most common etiology is the use of, misuse of, and failure to reverse neuromuscular blocking drugs (NMBDs). Patients might also present with underlying neuromuscular disorders at baseline or in an exacerbated state after surgery and anesthesia. Muscle weakness can lead to critical events such as respiratory failure and can delay recovery and discharge. The plan for prompt diagnosis and management of a patient with muscle weakness is presented. Knowledge of the pathophysiology, assessment, and treatment of perioperative muscle weakness is essential to ensure optimal patient outcomes.
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Machtinger, Edward L., and Peter A. Nigrovic. Spanish for Pediatric Medicine. Edited by Janice A. Lowe. 2nd ed. American Academy of Pediatrics, 2005. http://dx.doi.org/10.1542/9781581104554.
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Enhance patient and parent encounters with this newly expanded and enhanced pocket guide! Here's the easy-to-use manual you need to communicate with Spanish-speaking patients and parents more efficiently and effectively. Spanish for Pediatric Medicine features a quick-reference design that enables you to rapidly identify and explore common medical problems. English and Spanish equivalents are shown side-by-side for instant, precise use. This handy resource fits right in your pocket as you travel between well-child, sick visit, and emergency department settings. Optimized for use with Bright Futures--visit-specific translations from prenatal to 18- to 21-year visits reflect the organization of the AAP Bright Futures: Guidelines for Health Supervision of Infants, Children, and Adolescents, 3rd Edition. All-new audio program--electronic access to downloadable audio clips of translations from a native Spanish speaker helps you improve comprehension and pronunciation. The new 2nd edition includes general visit translations--medical history, family history, description of pain, examination instructions, immunization screening, and discharge instructions; Bright Futures stage visit translations--spanning issues addressed in prenatal and newborn through late adolescent visits; emergency department (ED) visit translations--ED history, description of pain, examination instructions, and discharge instructions; system-specific translations--hematology/oncology, skin, respiratory, cardiovascular, gastrointestinal, genitourinary, and musculoskeletal; special issues translations--abuse screening, developmental milestones, lead toxicity screening, and obesity prevention and treatment; and translations for commonly used expressions/greetings--terms of endearment for children.
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DeAugustinas, M., and A. Kiely. Periocular Infections. Oxford University Press, 2016. http://dx.doi.org/10.1093/med/9780199976805.003.0015.
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Periocular Infections occur when there is inflammation of the conjunctiva. Uncomplicated viral infections can usually be managed with careful hand hygiene and lubrication of the eye with artificial tears. More severe infections are notable for purulent discharge, membrane formation, and scarring, and can lead to corneal change. For suspected bacterial conjunctivitis, empiric therapy begins with broad spectrum antibiotic eye drops or ointment, which are supplemented with oral antibiotics in cases associated with pharyngitis and in children with H. influenzae infection. For gonococcal conjunctivitis, systemic ceftriaxone is recommended for both adults and children (including neonates) due to the increasing prevalence of penicillin-resistant N. gonorrhoeae. If the cornea is not involved and the patient is extremely reliable, next day referral to an ophthalmologist in addition to management with IM ceftriaxone is sufficient. Otherwise, admission for IV therapy is advised. Copious, repeated irrigation is also advised to remove inflammatory mediators and debris that can contribute to corneal melting.
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Putman, Shannon B. Cervicitis and Vulvovaginitis. Oxford University Press, 2016. http://dx.doi.org/10.1093/med/9780199976805.003.0038.
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Cervicitis is inflammation and irritation of uterine cervix often caused by sexually transmitted infection (STI); it can lead to pelvic inflammatory disease, endometritis, and pregnancy complications. Vulvovaginitis (inflammation of vagina and/or vulva with itching, erythema, and mucopurulent discharge) may or may not be related to STI. Sexually active women 25 years or younger with STIs should be offered empiric treatment for gonorrhea and chlamydia in addition to counseling regarding safe sex and testing for syphilis, HIV, and viral hepatitis at the time of presentation and prior to nucleic acid amplification testing results. Sexual partners of women testing positive for gonorrhea, chlamydia, or trichomoniasis should be informed and treated to prevent reinfection, with patients and their partners abstaining from intercourse until treatment is complete and symptoms resolve. High-risk patients with STI should be retested at 6 months given recurrent infection rates. Prophylaxis, vaccination, high degree of suspicion, and early intervention can help improve morbidity and mortality.
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Perrings, Charles, and Ann Kinzig. Conservation. Oxford University Press, 2021. http://dx.doi.org/10.1093/oso/9780190613600.001.0001.
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This book explores the process by which people decide to conserve or convert natural resources. Building on a seminal study by Harold Hotelling that connects conservation to expected changes in the value of resources, the authors develop the general principles involved in conservation science. The focus of the book is the resources of the natural environment. This includes both directly exploited resources such as agricultural soils, minerals, forests, and fish stocks, and biodiversity—the wild species and natural ecosystems put at risk when people choose to convert natural habitat, or to discharge waste products to water, land, or air. The theory of conservation shows how much or how little to extract from the environment, and how much to leave intact. It also shows how conservation decisions are influenced by the existence of market failures—the external impacts of market decisions on ecosystems, and the public good nature of many ecosystem services. It shows how conservation connects to expected changes in the relative importance or value of natural resources, and what is needed to uncover that value. It shows how context matters. Decisions about the conservation of natural resources are influenced by property rights—whether land is private property or in the public domain; by environmental policies, laws, and regulations within countries; and by environmental agreements between countries. Finally, this book shows how conservation differs within and beyond protected areas, how it connects to the system of environmental governance, and how governance structures have evolved over time.
Book chapters on the topic "Leader discharge"
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Xiao, Dengming. "Fundamental Theory of Streamer and Leader Discharge." In Energy and Environment Research in China, 89–121. Berlin, Heidelberg: Springer Berlin Heidelberg, 2016. http://dx.doi.org/10.1007/978-3-662-48041-0_4.
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Okubo, H., T. Takahashi, T. Yamada, and M. Hikita. "Discrimination of Streamer / Leader Type Partial Discharge in SF6 Gas Based on Discharge Mechanism." In Gaseous Dielectrics VIII, 269–75. Boston, MA: Springer US, 1998. http://dx.doi.org/10.1007/978-1-4615-4899-7_36.
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Conti, Mauro, Denis Donadel, Radha Poovendran, and Federico Turrin. "EVExchange: A Relay Attack on Electric Vehicle Charging System." In Computer Security – ESORICS 2022, 488–508. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-031-17140-6_24.
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AbstractTo support the increasing spread of Electric Vehicles (EVs), Charging Stations (CSs) are being installed worldwide. The new generation of CSs employs the Vehicle-To-Grid (V2G) paradigm by implementing novel standards such as the ISO 15118. This standard enables high-level communication between the vehicle and the charging column, helps manage the charge smartly, and simplifies the payment phase. This novel charging paradigm, which connects the Smart Grid to external networks (e.g., EVs and CSs), has not been thoroughly examined yet. Therefore, it may lead to dangerous vulnerability surfaces and new research challenges.In this paper, we present EVExchange, the first attack to steal energy during a charging session in a V2G communication: i.e., charging the attacker’s car while letting the victim pay for it. Furthermore, if reverse charging flow is enabled, the attacker can even sell the energy available on the victim’s car! Thus, getting the economic profit of this selling, and leaving the victim with a completely discharged battery. We developed a virtual and a physical testbed in which we validate the attack and prove its effectiveness in stealing the energy. To prevent the attack, we propose a lightweight modification of the ISO 15118 protocol to include a distance bounding algorithm. Finally, we validated the countermeasure on our testbeds. Our results show that the proposed countermeasure can identify all the relay attack attempts while being transparent to the user.
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Bazelyan, E. M., and Yu P. Raizer. "The Leader Process." In Spark Discharge, 203–60. Routledge, 2017. http://dx.doi.org/10.1201/9780203739075-6.
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"Chapter 5 Stepped Leader." In The Lightning Discharge, 82–98. Elsevier, 1987. http://dx.doi.org/10.1016/s0074-6142(08)60271-5.
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"Chapter 8 Dart Leader." In The Lightning Discharge, 154–66. Elsevier, 1987. http://dx.doi.org/10.1016/s0074-6142(08)60274-0.
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Beroual, A. "Application of the model to evaluate the induced effects on overhead lines due to a nearby positive lightning downward leader." In Discharge in Long Air Gaps Modelling and applications. IOP Publishing, 2016. http://dx.doi.org/10.1088/978-0-7503-1236-3ch13.
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Marson, James, and Katy Ferris. "10. Ending the Contract." In Business Law, 237–66. Oxford University Press, 2020. http://dx.doi.org/10.1093/he/9780198849957.003.0010.
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This chapter discusses other ways in which a valid contract may be discharged, aside from the successful completion of established rights and duties. It also discusses possible remedies where a party breaches the contract. Under the normal rules of contract, a party is only discharged from a contract when that party has completed obligations under it. Having completed the contract each party is free of further obligations. A failure to complete the contract may lead to a breach of contract claim, although situations exist where the parties may release each other from further obligation—referred to as discharge by agreement—or the contract may have been partially or substantially performed. This chapter examines discharge through performance and agreement, how contracts may become frustrated, and the consequences and remedies following a breach of contract.
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Marson, James, and Katy Ferris. "10. Discharge of Contract and Remedies for Breach." In Business Law. Oxford University Press, 2018. http://dx.doi.org/10.1093/he/9780198766285.003.0010.
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This chapter discusses other ways in which a valid contract may be discharged, aside from the successful completion of established rights and duties. It also discusses possible remedies where a party breaches the contract. Under the normal rules of contract, a party is only discharged from a contract when that party has completed obligations under it. Having completed the contract each party is free of further obligations. A failure to complete the contract may lead to a breach of contract claim, although situations exist where the parties may release each other from further obligation—referred to as discharge by agreement—or the contract may have been partially or substantially performed. This chapter examines discharge through performance and agreement, how contracts may become frustrated, and the consequences and remedies following a breach of contract.
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MacKenzie, Judith-Anne, and Aruna Nair. "9. The leasehold estate." In Textbook on Land Law, 172–224. Oxford University Press, 2020. http://dx.doi.org/10.1093/he/9780198839828.003.0009.
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Course-focused and comprehensive, the Textbook on Land Law provides an accessible overview of one key area on the law curriculum. This chapter considers the nature and characteristics of a lease, and the ways in which it is created and brought to an end. It discusses the basic requirements for a lease; the creation of leases; the disposition of leases and reversions; the determination of a lease; determination by discharge of contract; determination by joint tenants; ‘contractualisation’ of leases; the effect on subtenant of determination of head lease; and additional types of lease.
Conference papers on the topic "Leader discharge"
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Liu, L., B. Luo, C. Peng, X. Dong, Y. Zhao, and E. Li. "A simplified plasma model to calculate leader discharge channel temperature." In 18th International Conference on AC and DC Power Transmission (ACDC 2022). Institution of Engineering and Technology, 2022. http://dx.doi.org/10.1049/icp.2022.1317.
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Nagasawa, Satoru, Mengu Cho, Masayuki Hikita, and Hiromasa Takeno. "Leader development in laser-induced discharge under nonuniform dc electric field." In Advanced High-Power Lasers and Applications, edited by Kunioki Mima, Gerald L. Kulcinski, and William J. Hogan. SPIE, 2000. http://dx.doi.org/10.1117/12.375168.
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Shuai, Yuqi, Xiaohua Lv, Tao Long, and Ziqiang Xu. "Experimental study on thermal characteristics during leader discharge and its recovery procedure." In 2022 IEEE International Conference on High Voltage Engineering and Applications (ICHVE). IEEE, 2022. http://dx.doi.org/10.1109/ichve53725.2022.9961489.
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Blackwell, Sharon. "21 Discharge time and 30 day readmission rates from skilled nursing facilities." In Leaders in Healthcare Conference, 17–20 November 2020. BMJ Publishing Group Ltd, 2020. http://dx.doi.org/10.1136/leader-2020-fmlm.21.
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Diaz, Oscar, Vernon Cooray, and Liliana Arevalo. "Sensitivity analysis of leader channel models used in long air gap positive discharge modelling." In 2014 International Conference on Lightning Protection (ICLP). IEEE, 2014. http://dx.doi.org/10.1109/iclp.2014.6973188.
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Yusuf, Zahid, Lisa Bateman, and Rajeshwar Ranganathan. "6 A QIP to address patient-centred care by increasing the distribution of patient information leaflets (PILs) by 10%, at the point of patient discharge at Pilgrim Hospital ED, by March 2021." In Leaders in Healthcare 2021. BMJ Publishing Group Ltd, 2021. http://dx.doi.org/10.1136/leader-2021-fmlm.6.
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Hanai, Masahiro, Keisuke Suzuki, Ryunosuke Mizuno, Hiroki Kojima, Naoki Hayakawa, and Hitoshi Okubo. "Discrimination technique of streamer and leader type of partial discharge in SF6 gas using UHF method." In 2012 IEEE International Conference on Condition Monitoring and Diagnosis (CMD). IEEE, 2012. http://dx.doi.org/10.1109/cmd.2012.6416437.
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Dole, Natasha. "7 Improving the documentation of risk assessments and discharge advice in anti-coagulated patients with head injuries and normal imaginghead injuries & anticoagulation." In Leaders in Healthcare Conference, 17–20 November 2020. BMJ Publishing Group Ltd, 2020. http://dx.doi.org/10.1136/leader-2020-fmlm.7.
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Light, Alexander, Callum Donaldson, Usman Khatana, Zanil Nizar, and Iftikhar Nadeem. "34 Use of the DECAF score to facilitate early discharge for acute exacerbation of COPD patients: a quality improvement project at a district general hospital." In Leaders in Healthcare Conference, 17–20 November 2020. BMJ Publishing Group Ltd, 2020. http://dx.doi.org/10.1136/leader-2020-fmlm.34.
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Parker, Hannah, and Georgia Asher. "36 Medically safe for discharge (MSFD): reducing doctor input in MSFD patients across geriatric medicine wards at a DGH in Somerset." In FMLM International Healthcare Leadership Conference 2022. BMJ Publishing Group Ltd, 2023. http://dx.doi.org/10.1136/leader-2023-fmlm.26.
Full textReports on the topic "Leader discharge"
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Dow, Nick, and Daniel Madrzykowski. Residential Flashover Prevention with Reduced Water Flow: Phase 2. UL's Fire Safety Research Institute, November 2021. http://dx.doi.org/10.54206/102376/nuzj8120.
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The purpose of this study was to investigate the feasibility of a residential flashover prevention system with reduced water flow requirements relative to a residential sprinkler system designed to meet NFPA 13D requirements. The flashover prevention system would be designed for retrofit applications where water supplies are limited. In addition to examining the water spray’s impact on fire growth, this study utilized thermal tenability criteria as defined in UL 199, Standard for Automatic Sprinklers for Fire-Protection Service. The strategy investigated was to use full cone spray nozzles that would discharge water low in the fire room and directly onto burning surfaces of the contents in the room. Where as current sprinkler design discharges water in a manner that cools the hot gas layer, wets the walls and wets the surface of the contents in the fire room. A series of eight full-scale, compartment fire experiments with residential furnishings were conducted with low flow nozzles. While the 23 lpm (6 gpm) of water was the same between experiments, the discharge density or water flux around the area of ignition varied between 0.3 mm/min (0.008 gpm/ft2) and 1.8 mm/min (0.044 gpm/ft2). Three of the experiments prevented flashover. Five of the experiments resulted in the regrowth of the fire while the water was flowing. Regrowth of the fire led to untenable conditions, per UL 199 criteria, in the fire room. At approximately the same time as the untenability criteria were reached, the second sprinkler in the hallway activated. In a completed system, the activation of the second sprinkler would reduce the water flow to the fire room, which would potentially lead to flashover. The variations in the burning behavior of the sofa resulted in shielded fires which led to the loss of effectiveness of the reduced flow solid cone water sprays. As a result of these variations, a correlation between discharge density at the area of ignition and fire suppression performance could not be determined given the limited number of experiments. An additional experiment using an NFPA 13D sprinkler system, flowing 30 lpm (8 gpm), demonstrated more effective suppression than any of the experiments with a nozzle. The success of the sprinkler compared with the unreliable suppression performance of the lower flow nozzles supports the minimum discharge density requirements of 2 mm/min (0.05 gpm/ft2) from NFPA 13D. The low flow nozzle system tested in this study reliably delayed fire growth, but would not reliably prevent flashover.
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Tipton, Kelley, Brian F. Leas, Nikhil K. Mull, Shazia M. Siddique, S. Ryan Greysen, Meghan B. Lane-Fall, and Amy Y. Tsou. Interventions To Decrease Hospital Length of Stay. Agency for Healthcare Research and Quality (AHRQ), September 2021. http://dx.doi.org/10.23970/ahrqepctb40.
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Background. Timely discharge of hospitalized patients can prevent patient harm, improve patient satisfaction and quality of life, and reduce costs. Numerous strategies have been tested to improve the efficiency and safety of patient recovery and discharge, but hospitals continue to face challenges. Purpose. This Technical Brief aimed to identify and synthesize current knowledge and emerging concepts regarding systematic strategies that hospitals and health systems can implement to reduce length of stay (LOS), with emphasis on medically complex or vulnerable patients at high risk for prolonged LOS due to clinical, social, or economic barriers to timely discharge. Methods. We conducted a structured search for published and unpublished studies and conducted interviews with Key Informants representing vulnerable patients, hospitals, health systems, and clinicians. The interviews provided guidance on our research protocol, search strategy, and analysis. Due to the large and diverse evidence base, we limited our evaluation to systematic reviews of interventions to decrease hospital LOS for patients at potentially higher risk for delayed discharge; primary research studies were not included, and searches were restricted to reviews published since 2010. We cataloged the characteristics of relevant interventions and assessed evidence of their effectiveness. Findings. Our searches yielded 4,364 potential studies. After screening, we included 19 systematic reviews reported in 20 articles. The reviews described eight strategies for reducing LOS: discharge planning; geriatric assessment or consultation; medication management; clinical pathways; inter- or multidisciplinary care; case management; hospitalist services; and telehealth. All reviews included adult patients, and two reviews also included children. Interventions were frequently designed for older (often frail) patients or patients with chronic illness. One review included pregnant women at high risk for premature delivery. No reviews focused on factors linking patient vulnerability with social determinants of health. The reviews reported few details about hospital setting, context, or resources associated with the interventions studied. Evidence for effectiveness of interventions was generally not robust and often inconsistent—for example, we identified six reviews of discharge planning; three found no effect on LOS, two found LOS decreased, and one reported an increase. Many reviews also reported patient readmission rates and mortality but with similarly inconsistent results. Conclusions. A broad range of strategies have been employed to reduce LOS, but rigorous systematic reviews have not consistently demonstrated effectiveness within medically complex, high-risk, and vulnerable populations. Health system leaders, researchers, and policymakers must collaborate to address these needs.
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Douglas, Thomas, Matthew Sturm, Joel Blum, Christopher Polashenski, Svetlana Stuefer, Christopher Hiemstra, Alexandra Steffen, Simon Filhol, and Romain Prevost. A pulse of mercury and major ions in snowmelt runoff from a small Arctic Alaska watershed. Engineer Research and Development Center (U.S.), July 2021. http://dx.doi.org/10.21079/11681/41203.
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Atmospheric mercury (Hg) is deposited to Polar Regions during springtime atmospheric mercury depletion events (AMDEs) that require halogens and snow or ice surfaces. The fate of this Hg during and following snowmelt is largely unknown. We measured Hg, major ions, and stable water isotopes from the snowpack through the entire spring melt runoff period for two years. Our small (2.5 ha) watershed is near Barrow (now Utqiaġvik), Alaska. We measured discharge, made 10 000 snow depths, and collected over 100 samples of snow and meltwater for chemical analysis in 2008 and 2009 from the watershed snowpack and ephemeral stream channel. Our results suggest AMDE Hg complexed with Cl⁻ or Br⁻ may be less likely to be photochemically reduced and re-emitted to the atmosphere prior to snowmelt, and we estimate that roughly 25% of the Hg in snowmelt is attributable to AMDEs. Projected Arctic warming, with more open sea ice leads providing halogen sources that promote AMDEs, may provide enhanced Hg deposition, reduced Hg emission and, ultimately, an increase in snowpack and snowmelt runoff Hg concentrations.
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Desiderati, Christopher. Carli Creek Regional Water Quality Project: Assessing Water Quality Improvement at an Urban Stormwater Constructed Wetland. Portland State University, 2022. http://dx.doi.org/10.15760/mem.78.
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Stormwater management is an ongoing challenge in the United States and the world at-large. As state and municipal agencies grapple with conflicting interests like encouraging land development, complying with permits to control stormwater discharges, “urban stream syndrome” effects, and charges to steward natural resources for the long-term, some agencies may turn to constructed wetlands (CWs) as aesthetically pleasing and functional natural analogs for attenuating pollution delivered by stormwater runoff to rivers and streams. Constructed wetlands retain pollutants via common physical, physicochemical, and biological principles such as settling, adsorption, or plant and algae uptake. The efficacy of constructed wetlands for pollutant attenuation varies depending on many factors such as flow rate, pollutant loading, maintenance practices, and design features. In 2018, the culmination of efforts by Clackamas Water Environment Services and others led to the opening of the Carli Creek Water Quality Project, a 15-acre constructed wetland adjacent to Carli Creek, a small, 3500-ft tributary of the Clackamas River in Clackamas County, OR. The combined creek and constructed wetland drain an industrialized, 438-acre, impervious catchment. The wetland consists of a linear series of a detention pond and three bioretention treatment cells, contributing a combined 1.8 acres of treatment area (a 1:243 ratio with the catchment) and 3.3 acre-feet of total runoff storage. In this study, raw pollutant concentrations in runoff were evaluated against International Stormwater BMP database benchmarks and Oregon Water Quality Criteria. Concentration and mass-based reductions were calculated for 10 specific pollutants and compared to daily precipitation totals from a nearby precipitation station. Mass-based reductions were generally higher for all pollutants, largely due to runoff volume reduction on the treatment terrace. Concentration-based reductions were highly variable, and suggested export of certain pollutants (e.g., ammonia), even when reporting on a mass-basis. Mass load reductions on the terrace for total dissolved solids, nitrate+nitrite, dissolved lead, and dissolved copper were 43.3 ± 10%, 41.9 ± 10%, 36.6 ± 13%, and 43.2 ± 16%, respectively. E. coli saw log-reductions ranging from -1.3 — 3.0 on the terrace, and -1.0 — 1.8 in the creek. Oregon Water Quality Criteria were consistently met at the two in-stream sites on Carli Creek for E. coli with one exception, and for dissolved cadmium, lead, zinc, and copper (with one exception for copper). However, dissolved total solids at the downstream Carli Creek site was above the Willamette River guidance value 100 mg/L roughly 71% of the time. The precipitation record during the study was useful for explaining certain pollutant reductions, as several mechanisms are driven by physical processes, however it was not definitive. The historic rain/snow/ice event in mid-February 2021 appeared to impact mass-based reductions for all metals. Qualitatively, precipitation seemed to have the largest effect on nutrient dynamics, specifically ammonia-nitrogen. Determining exact mechanisms of pollutant removals was outside the scope of this study. An improved flow record, more targeted storm sampling, or more comprehensive nutrient profiles could aid in answering important questions on dominant mechanisms of this new constructed wetland. This study is useful in establishing a framework and baseline for understanding this one-of-a-kind regional stormwater treatment project and pursuing further questions in the future.
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Warrick, Arthur W., Gideon Oron, Mary M. Poulton, Rony Wallach, and Alex Furman. Multi-Dimensional Infiltration and Distribution of Water of Different Qualities and Solutes Related Through Artificial Neural Networks. United States Department of Agriculture, January 2009. http://dx.doi.org/10.32747/2009.7695865.bard.
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The project exploits the use of Artificial Neural Networks (ANN) to describe infiltration, water, and solute distribution in the soil during irrigation. It provides a method of simulating water and solute movement in the subsurface which, in principle, is different and has some advantages over the more common approach of numerical modeling of flow and transport equations. The five objectives were (i) Numerically develop a database for the prediction of water and solute distribution for irrigation; (ii) Develop predictive models using ANN; (iii) Develop an experimental (laboratory) database of water distribution with time; within a transparent flow cell by high resolution CCD video camera; (iv) Conduct field studies to provide basic data for developing and testing the ANN; and (v) Investigate the inclusion of water quality [salinity and organic matter (OM)] in an ANN model used for predicting infiltration and subsurface water distribution. A major accomplishment was the successful use of Moment Analysis (MA) to characterize “plumes of water” applied by various types of irrigation (including drip and gravity sources). The general idea is to describe the subsurface water patterns statistically in terms of only a few (often 3) parameters which can then be predicted by the ANN. It was shown that ellipses (in two dimensions) or ellipsoids (in three dimensions) can be depicted about the center of the plume. Any fraction of water added can be related to a ‘‘probability’’ curve relating the size of the ellipse (or ellipsoid) that contains that amount of water. The initial test of an ANN to predict the moments (and hence the water plume) was with numerically generated data for infiltration from surface and subsurface drip line and point sources in three contrasting soils. The underlying dataset consisted of 1,684,500 vectors (5 soils×5 discharge rates×3 initial conditions×1,123 nodes×20 print times) where each vector had eleven elements consisting of initial water content, hydraulic properties of the soil, flow rate, time and space coordinates. The output is an estimate of subsurface water distribution for essentially any soil property, initial condition or flow rate from a drip source. Following the formal development of the ANN, we have prepared a “user-friendly” version in a spreadsheet environment (in “Excel”). The input data are selected from appropriate values and the output is instantaneous resulting in a picture of the resulting water plume. The MA has also proven valuable, on its own merit, in the description of the flow in soil under laboratory conditions for both wettable and repellant soils. This includes non-Darcian flow examples and redistribution and well as infiltration. Field experiments were conducted in different agricultural fields and various water qualities in Israel. The obtained results will be the basis for the further ANN models development. Regions of high repellence were identified primarily under the canopy of various orchard crops, including citrus and persimmons. Also, increasing OM in the applied water lead to greater repellency. Major scientific implications are that the ANN offers an alternative to conventional flow and transport modeling and that MA is a powerful technique for describing the subsurface water distributions for normal (wettable) and repellant soil. Implications of the field measurements point to the special role of OM in affecting wettability, both from the irrigation water and from soil accumulation below canopies. Implications for agriculture are that a modified approach for drip system design should be adopted for open area crops and orchards, and taking into account the OM components both in the soil and in the applied waters.
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Personal discharge plans may lead to shorter hospital stays and fewer readmissions. National Institute for Health Research, March 2016. http://dx.doi.org/10.3310/signal-000224.
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Zimbabwe: RTI screening methods for women are not cost-effective. Population Council, 1999. http://dx.doi.org/10.31899/rh1999.1012.
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Reproductive tract infections (RTIs) are common in Zimbabwe. Many RTIs increase the risk of human immunodeficiency virus (HIV) infection. In 1998, the Zimbabwe National Family Planning Council (ZNFPC) conducted an operations research study to assess the feasibility of adding RTI diagnosis and treatment to its menu of services. The study population consisted of 1,634 clients at three ZNFPC clinics. Each client was asked about lower abdominal pain, vaginal discharge, and other RTI symptoms; examined for clinical signs of RTIs; and given laboratory tests to confirm the accuracy of diagnosis based upon symptoms and signs. Findings detailed in this brief were that existing methods for screening RTIs among family planning clients are not cost-effective, laboratory tests are too costly, and syndromic case management often leads to missed infections and unnecessary treatment. Health programs should continue to emphasize preventive measures—changing individual behavior and promoting condom use.
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Composition, distribution, and hydrologic effects of contaminated sediments resulting from the discharge of gold milling wastes to Whitewood Creek at Lead and Deadwood, South Dakota. US Geological Survey, 1989. http://dx.doi.org/10.3133/wri874051.
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Comparative Analysis on Fuel Consumption Between Two Online Strategies for P2 Hybrid Electric Vehicles: Adaptive-RuleBased (A-RB) vs Adaptive-Equivalent Consumption Minimization Strategy (A-ECMS). SAE International, March 2022. http://dx.doi.org/10.4271/2022-01-0740.
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Hybrid electric vehicles (HEVs) represent one of the main technological options for reducing vehicle CO2 emissions, helping car manufacturers (OEMs) to meet the stricter targets which are set by the European Green Deal for new passenger cars at 80 g CO2/km by 2025. The optimal power-split between the internal combustion engine (ICE) and the electric motor is a challenge since it depends on many unpredictable variables. In fact, HEV improvements in fuel economy and emissions strongly depend on the energy management strategy (EMS) on-board of the vehicle. Dynamic Programming approach (DP), direct methods and Pontryagin’s minimum principle (PMP) are some of the most used methodologies to optimize the HEV power-split. In this paper two online strategies are evaluated: an Adaptive-RuleBased (A-RB) and an Adaptive-Equivalent Consumption Minimization Strategy (A-ECMS). At first, a description of the P2 HEV model is made. Second, the two sub-optimal strategies are described in detail and then implemented on the HEV model to derive the fuel-optimal control strategy managing the power split between the thermal and electric engine to satisfy the driver's power request, including the engine on/off operating mode and the best gear selection. Finally, the two proposed strategies are tested on different driving cycles and then compared to other commercial strategies available in literature, such as the Equivalent Consumption Minimization Strategy (ECMS) and a RuleBased (RB) strategy. The results show that the A-ECMS is more conservative in terms of state of charge (SoC) compared to the A-RB. In fact, in the A-ECMS the SoC is always within the admissible range with considerable margin from the upper and lower limits for tested cycles, while in the A-RB a deep discharge of the battery is allowed. This behavior leads to a better fuel consumption of the A-RB compared to the A-ECMS, both in the WLTC and in the FTP-75 cycle.