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Drascic-Gaudio, Meghan, Hailey Graham e Madeleine Howard. "Igniting Connections". IJournal: Graduate Student Journal of the Faculty of Information 4, n. 3 (26 settembre 2019): 28–36. http://dx.doi.org/10.33137/ijournal.v4i3.33077.
Testo completoAbstract (sommario):
Redefining Home: A Story of Japanese Canadian Resettlement in Toronto explores the story of Harold and Hana Kawasoe, a young Japanese Canadian couple, who chose Toronto as their new home in the face of immeasurable loss they, and many other Japanese Canadians faced during the Second World War. Using a co-curation approach to share the Kawasoe story, the exhibit team discovered how community collaboration and the facilitation of diverse experiences can organically create support and success for museums and historic houses. Redefining Home offers a lens through which the strengths and weaknesses of this method can be seen, and this paper further discusses how it can be implemented by others going forward. Igniting community connections and creating platforms for many voices offers museums valuable and important insight into diverse and unique narratives.
Keywords:
case study, community collaboration, museums, exhibition development, co-curation
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Zhang, Hong Jun, Zhi Xiang Yang, Fu Xing Zhang e Xian Zhi Yang. "Research and Application of Technology of Mobile Electric Ignition Technology for Fire Flood in Vertical Hole". Advanced Materials Research 1008-1009 (agosto 2014): 356–60. http://dx.doi.org/10.4028/www.scientific.net/amr.1008-1009.356.
Testo completoAbstract (sommario):
In-Situ combustion is an important transformation mode for heavy oil development, and the key to its success is ignition in the reservoir, On the basis of investigation and research into some related techniques both at home and abroad, this paper presents the development of mobile electric igniter, technical string, down-hole monitoring system, putting-in and putting-out device; the integral outside diameter of the igniter is φ25.4mm; this paper forms the technique of mobile electric ignition for fire flood in vertical hole and introduces the technical principle. The field test results show that the maximum outlet air temperature of the igniter is 527°C when the steam injection rate is 6500Nm3/d; And that realizes high temperature igniting of mobile electric igniter for the first time. This technique will effectively reduce the operation cost of fire flood, and provides technical reserve for separate zone ignition in thick mass oil pool of Liaohe Oilfield.
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Li, Yunan. "Apple Inc. Analysis and Forecast Evaluation". Proceedings of Business and Economic Studies 4, n. 4 (27 agosto 2021): 71–78. http://dx.doi.org/10.26689/pbes.v4i4.2389.
Testo completoAbstract (sommario):
Apple has been an American success story for quite a long time. After igniting the personal computer (PC) revolution in the 1970s and reinventing PC in the 1980s, it again brought various innovative and game-changing products, including smartphones, computers, and wearables in recent years. Its dominant product, iPhone, sparked years of massive growth and has become the biggest drive of the company’s success. Besides, with a market capitalization of more than $2T, Apple is currently the world’s most valuable company. This makes many investors interested in AAPL stock. Hence, this paper will explore whether the APPL stock is worth investing based on the analysis of its business model, SWOT analysis, and relative valuation in hope to provide some recommendations and predictions for investors.
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Collins, Clare E. "Igniting your passion for research impact and success: A guide for early career nutrition researchers!" Nutrition & Dietetics 81, n. 2 (aprile 2024): 124–27. http://dx.doi.org/10.1111/1747-0080.12875.
Testo completo
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Fan, Zi Ming, e Juo Lan Yeh. "Career development impact on architecture undergrads’ employment: learning motivation mediation". International Journal of Evaluation and Research in Education (IJERE) 13, n. 5 (1 ottobre 2024): 3231. http://dx.doi.org/10.11591/ijere.v13i5.28446.
Testo completoAbstract (sommario):
This study, utilizing the expectancy-value theory, examines the relationship between career development, learning motivation, and employment capabilities among Chinese architecture undergraduates. Surveying 319 students from five Chinese universities, the research reveals that career development has a positive impact on both employment capabilities and learning motivation. Learning motivation, in turn, positively affects employment capabilities and acts as a mediator between career development and employment capabilities. These findings underscore the significance of proactive career planning, goal setting, and intrinsic learning motivation in enhancing students' employment capabilities. For practical applications, educational institutions can design comprehensive career development programs to assist students in defining career goals and igniting intrinsic motivation for learning, thereby fostering career success and employability among architecture students.
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Smith, Brandy D. "Innovations in Higher Education: Igniting the Spark for Success ed. by Allan M. Hoffman and Stephen D. Spangehl". Review of Higher Education 37, n. 1 (2013): 128–30. http://dx.doi.org/10.1353/rhe.2013.0064.
Testo completo
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Zuo, W. "ВНУТРЕННЕЕ ПРЕДПРИНИМАТЕЛЬСТВО КАК РАСТУЩИЙ ЗАПРОС: ФОРМИРОВАНИЕ ПРЕДПРИНИМАТЕЛЬСКОГО МЫШЛЕНИЯ ДЛЯ СТИМУЛИРОВАНИЯ СТРАТЕГИЧЕСКОГО ИННОВАЦИОННОГО ПОВЕДЕНИЯ СОТРУДНИКОВ". Human Progress 9, n. 3 (25 luglio 2023): 14. http://dx.doi.org/10.34709/im.193.14.
Testo completoAbstract (sommario):
The effect of having an entrepreneurial attitude on employee performance has been recognized in earlier studies. This study aims to investigate the link between an entrepreneurial mindset and intrapreneurial activity among employees. Additionally, we explore how situational cues can encourage an entrepreneurial mindset. As a research tool, we used a developed questionnaire with appropriate scales, which allows to quantify the factors that are important for our study, such as involvement in work, psychological safety, entrepreneurial attitude, etc. Further, the necessary information was collected on this questionnaire, which was processed, first of all, using SPSS 26, and then we analyzed the structural equations using Mplus 8.0. The findings of this study show that supporting employees' intrapreneurial behavior, which is commonly seen as a crucial factor in organizational success and productivity, requires an entrepreneurial mindset. The study has also identified psychological safety and job engagement as the key cues that stimulate employees' entrepreneurial mindsets. Влияние предпринимательского подхода на эффективность работы сотрудников было признано в более ранних исследованиях. Целью этого исследования является изучение связи между предпринимательским мышлением и предпринимательской активностью сотрудников. Кроме того, мы исследуем, как ситуационные сигналы могут способствовать развитию предпринимательского мышления. В качестве инструмента исследования была использована разработанная нами анкета с соответствующими шкалами, позволяющая количественно оценить факторы, имеющие значение для нашего исследования, такие как вовлеченность в работу, психологическая безопасность, предпринимательское мышление и др. Далее по этой анкете была собрана необходимая информация, которая была обработана нами, в первую очередь, с использованием SPSS 26, а затем проведен анализ структурных уравнений с использованием Mplus 8.0. Результаты этого исследования показывают, что поддержка внутрифирменного предпринимательского поведения сотрудников, которое обычно рассматривается как решающий фактор успеха и эффективности организации, требует предпринимательского склада ума. Исследование также выявило психологическую безопасность и вовлеченность в работу в качестве ключевых факторов, стимулирующих предпринимательский настрой сотрудников.
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Riak PhD, Gabriel Alier, e Dut Bol Ayuel Bill. "THE IMPACT OF LEADERSHIP STYLES IN THE DEVELOPMENT". IJRDO - Journal of Social Science and Humanities Research 8, n. 11 (5 novembre 2022): 98–99. http://dx.doi.org/10.53555/sshr.v8i11.5367.
Testo completoAbstract (sommario):
Leadership is the ability to employ managerial competencies to organized performance processes by inspiring, igniting and motivating teams to meet set organizational goals (Kirega, 2008).According to Ogbonnia (2007), an operational map for leadership was drawn along: corporate style, authoritative style, and laissez-faire style. At the organizational level, leadership establishes and transmits to all employees the overarching direction of the organization, as such, developing a better understanding of effective leaders is important for future leader development (Gupta, 2005). The European Foundation for Quality Management (EFQM), (2009) defines leadership at the strategic level as "how leaders develop and facilitate the achievement of the mission and vision, develop values required for long-term success and implement these via appropriate actions and behaviors, and are personally involved in ensuring that the organization’s management system is developed and implemented. To maintain a competitive edge, an organization must be able to adapt and change in order to improve processes. Leadership is a key component to achieving these outcomes (Keith, 2009).
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Mansouri, Ehsan, Amirhosein Mostajabi, Wolfgang Schulz, Gerhard Diendorfer, Marcos Rubinstein e Farhad Rachidi. "On the Use of Benford’s Law to Assess the Quality of the Data Provided by Lightning Locating Systems". Atmosphere 13, n. 4 (30 marzo 2022): 552. http://dx.doi.org/10.3390/atmos13040552.
Testo completoAbstract (sommario):
Lightning causes significant damage and casualties globally by directly striking humans and livestock, by igniting forest fires, and by inducing electrical surges in electronic infrastructure, airplanes, rockets, etc. Monitoring the evolution of thunderstorms by tracking lightning events using lightning locating systems can help prepare for and mitigate these disasters. In this work, we propose to use Benford’s law to assess the quality of the data provided by lightning locating systems. The Jensen–Shannon and Wasserstein distances between the recorded data distribution and Benford’s distribution are used as metrics for measuring the performance of the lightning locating systems. The data are provided by the European lightning detection network (EUCLID) for the years from 2000 to 2020. The two decades consist of three time windows between which the lightning locating system underwent several upgrades to improve the detection of both positive and negative strokes. The analysis shows that the agreement with Benford’s law is consistent with the expected behavior caused by the applied upgrades to the system throughout the years. The study suggests that the proposed approach can be used to test the success of software and hardware upgrades and to monitor the performance of lightning locating systems.
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Alshuriqi, Shatha Hilal, Balqees Saed Al Mahrouqi e Mohammed Muneerali Thottoli. "Igniting the IT Flame: a Study on IT Skills and Knowledge in Accounting Programs Among Graduating Students in Oman". Social Science Studies 3, n. 5 (30 settembre 2023): 359–79. http://dx.doi.org/10.47153/sss35.7332023.
Testo completoAbstract (sommario):
Purpose: Accountants have always been information technology (IT) users, and the case for increasing IT skills and Knowledge by accounting practitioners and graduates is stronger than ever. In business, IT is widely used and is getting more so. Without IT tools, achieving users' requirements for financial statements and other management information systems reports is no longer possible. Academics and practitioners have recognized the significance and IT (skills and Knowledge) in achieving success in the competitive business environment. Accountants who work for businesses, IT (skills and Knowledge) have necessitated the development of a new type of accountant, which is the focus of this study. Hence, this study aims to know the relationship between IT (skills and Knowledge) of accounting graduating students in Oman and university accounting programs.
Design/ Methodology/ Approach: The units of analysis for this study are graduating students in Oman. It used a survey for the year 2022 to study the effect of IT (skills and Knowledge) and accounting programs among graduating students in Oman. The present research tested its hypotheses and utilized its variables using the PLS software for data analysis.
Findings: The result revealed that IT Knowledge was significant with Accounting Programs where it was p<0.01, t ˃2.33. This result indicates that IT Knowledge has a significant impact on Accounting Programs. Further, the result revealed that IT Skills were also significant in Accounting Programs where it was p< 0.01, t=2.434. This result indicates that IT Skills have a significant impact on Accounting Programs.
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Uddin, Md Abu Saleh Nizam. "From home to homelessness: A reflection on Nora�s possible post-departure feminist life in A Doll�s House by Henrik Ibsen". EduLite: Journal of English Education, Literature and Culture 7, n. 2 (31 agosto 2022): 296. http://dx.doi.org/10.30659/e.7.2.296-310.
Testo completoAbstract (sommario):
In Henrik Ibsen�s A Doll�s House, Nora�s departure from home being hurt by her husband�s behavior appears to be the most important event of the drama igniting so far a wide critical parlances of Feminist array that appreciate the departure as Nora�s freedom from male-dominated society. But Nora�s success in having a home of comfort and happiness in her post-departure future life in Feminist world deserves critical attention too. We may posit Nora will shift to a Feminist world considering the departure as the manifestation of her newly imbibed Feminist spirit because the first wave Feminism of her time is either indifferent about or antagonistic to family life by being politics-centric. However, when Nora has within her a woman�s indispensable family-centric female construction to face nonfamilial politics-centric first wave feminism, she is sure to find no home in that Feminist world. Thus, this paper aims at examining how Nora, with her declared departure from home, is going to shift to the world of first wave Feminism which, by being nonfamilial and politics-centric, works against the very family-centric construction of Nora�s female construction and offers homelessness to her.�
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Santos, Luis, Vasco Lopes e Cecília Baptista. "MDIR Monthly Ignition Risk Maps, an Integrated Open-Source Strategy for Wildfire Prevention". Forests 13, n. 3 (3 marzo 2022): 408. http://dx.doi.org/10.3390/f13030408.
Testo completoAbstract (sommario):
Countries unaccustomed to wildfires are currently experiencing wildfire as a new climate-change reality. Understanding how fire ignition and propagation are correlated with temperature, orography, humidity, wind, and the mixture and age of individual plants must be considered when designing prevention strategies. While wildfire prevention focuses on fire ignition avoidance, firefighting success depends on early ignition detection, meaning that, in either case, ignition plays a major role. The current case study considered three Portuguese municipalities that annually observe frequent fire ignitions (Tomar, Ourém, and Ferreira do Zêzere) as the testing ground for the Modernized Dynamic Ignition Risk (MDIR) strategy, thus evaluating the efficiency of MDIR and the efficacy of the variables used. This methodology uses geographic information systems technology sustained by open-source satellite imagery, along with the Habitat Risk Assessment model from the InVEST software package, as drivers for the MDIR application. The MDIR approach grants frequent update capabilities and fully open-sourced high ignition risk area identification, producing monthly ignition risk maps. The advantage of using this method is the ease of adaptation to any current monitoring strategy, awarding further efficiency and efficacy in reducing ignitions. The approach delivered adequate results in estimating ignitions for the three Portuguese municipalities, achieving, for several months, prediction accuracy percentages of over 70%. For the studied area, MDIR clearly identifies areas of high ignition risk and delivers an average of 62% success in predicting ignitions, thus showing potential for analyzing the impact of policy implementation and monitoring through the strategy design.
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Wei, Wu. "The Effect of Group Cooperation on College Students’ Learning Motivation". Journal of Education, Humanities and Social Sciences 26 (2 marzo 2024): 845–50. http://dx.doi.org/10.54097/p7ezys61.
Testo completoAbstract (sommario):
The author explores the multifaceted benefits of group work in education, focusing on its impact on students' interest, engagement, self-efficacy, creativity, critical thinking, and social skills. Group work is portrayed as a dynamic approach that transforms the learning experience into an interactive and compelling journey. It enhances interest by introducing diverse learning activities and formats, preventing monotony, and actively involving students in discussions, problem-solving, and hands-on projects. The passage emphasizes group work's role in facilitating learning engagement, promoting active participation, social interaction, and critical thinking. Furthermore, it highlights how group work stimulates student creativity through collaboration, diverse perspectives, and activities like brainstorming and problem-solving. The discussion then delves into the positive influence of group work on students' self-efficacy. It shapes self-awareness through peer assessment, fostering a deeper understanding of strengths and weaknesses. Additionally, healthy peer competition within group work is presented as a motivating factor, inspiring students to strive for excellence and view challenges as opportunities for growth. Lastly, the passage explores group work's contribution to critical thinking and social skills. Group discussions are identified as a catalyst for nurturing critical thinking skills, encouraging students to question assumptions, explore alternative perspectives, and analyze information. The social dimension of group work is portrayed as instrumental in enhancing communication, teamwork, and conflict resolution skills, preparing students for success in both academic and professional realms. In summary, group work emerges as a transformative educational tool that goes beyond traditional learning methods, fostering a holistic development of students by igniting interest, promoting engagement, shaping self-efficacy, stimulating creativity, enhancing critical thinking, and cultivating essential social skills.
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Pandey, Chandrashekhar, Dinesh Rokaya e Bishwa Prakash Bhattarai. "Contemporary Concepts in Osseointegration of Dental Implants: A Review". BioMed Research International 2022 (14 giugno 2022): 1–11. http://dx.doi.org/10.1155/2022/6170452.
Testo completoAbstract (sommario):
In a society highly conscious of esthetics, prosthetic rehabilitation of lost teeth with tissue-integrated implants has gained wide acceptance and demand by patients and clinicians. The backbone of these tissue-integrated implants is the biotechnical process of osseointegration. Although the concept has been introduced and discussed for ages, the deepening knowledge about its cellular and molecular mechanisms has led the researchers to borrow further into the factors influencing the process of osseointegration. This has aided in the hastening and improving the process of osseointegration by exploiting several, even the minutest, details and events taking place in this natural process. Recently, due to the high esthetic expectations of the patients, the implants are being loaded immediately, which demands a high degree of implant stability. Implant stability, especially secondary stability, largely depends on bone formation and integration of implants to the osseous tissues. Various factors that influence the rate and success of osseointegration can either be categorized as those related to implant characteristics like the physical and chemical macro- and microdesign of implants or the bone characteristics like the amount and quality of bone and the local and systemic host conditions, or the time or protocol followed for the functional loading of the dental implant. To address the shortcomings in osseointegration due to any of the factors, it is mandatory that continuous and reliable monitoring of the status of osseointegration is done. This review attempts to encompass the mechanisms, factors affecting, and methods to assess osseointegration, followed by a discussion on the recent advances and future perspectives in dental implantology to enhance the process of osseointegration. The review was aimed at igniting the inquisitive minds to usher further the development of technology that enhances osseointegration.
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Fitriani, Diah Veny. "PEMANFAATAN MEDIA DAN SUMBER BELAJAR UNTUK PENGEMBANGAN KOGNITIF AUD". Jurnal Bocil: Journal of Childhood Education, Development and Parenting 1, n. 2 (15 maggio 2023): 91–98. http://dx.doi.org/10.28926/bocil.v1i2.951.
Testo completoAbstract (sommario):
The development of science and technology demands high-quality natural resources that are capable of facing various challenges. Therefore, education must always be taken into account and prioritized to produce quality individuals. Teachers, as one of the important components of successful learning, must be able to position themselves as figures who can ignite students' passion for learning. Teachers play a crucial role in the success of learning. They are not just instructors but also motivators and drivers of students' learning interest. An effective teacher should be able to ignite students' desire to learn.
One way teachers can achieve this is by understanding the needs and interests of students. Teachers need to recognize the characteristics and potentials of each student so that they can adapt teaching methods and materials accordingly. Teachers also need to build positive emotional relationships with students so that students feel comfortable and motivated to learn. Additionally, teachers need to utilize various technologies and innovations in the learning process. The use of technology can help teachers present materials in a more engaging and interactive way, making students more interested and involved in learning. By leveraging technology, teachers can also bring relevant and up-to-date content into the learning environment.
Moreover, teachers should serve as role models for students. They should have in-depth knowledge and continue to develop themselves in their field. Teachers with up-to-date knowledge will be able to inspire and motivate students to continue learning and self-development. In the face of rapid developments in science and technology, education must always be taken into account and prioritized. Teachers, as crucial components of successful learning, have a crucial role in igniting students' passion for learning. With quality education, it is expected to create human resources capable of facing various challenges in the era of scientific and technological advancements.
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Syphard, Alexandra D., e Jon E. Keeley. "Location, timing and extent of wildfire vary by cause of ignition". International Journal of Wildland Fire 24, n. 1 (2015): 37. http://dx.doi.org/10.1071/wf14024.
Testo completoAbstract (sommario):
The increasing extent of wildfires has prompted investigation into alternative fire management approaches to complement the traditional strategies of fire suppression and fuels manipulation. Wildfire prevention through ignition reduction is an approach with potential for success, but ignitions result from a variety of causes. If some ignition sources result in higher levels of area burned, then ignition prevention programmes could be optimised to target these distributions in space and time. We investigated the most common ignition causes in two southern California sub-regions, where humans are responsible for more than 95% of all fires, and asked whether these causes exhibited distinct spatial or intra-annual temporal patterns, or resulted in different extents of fire in 10–29-year periods, depending on sub-region. Different ignition causes had distinct spatial patterns and those that burned the most area tended to occur in autumn months. Both the number of fires and area burned varied according to cause of ignition, but the cause of the most numerous fires was not always the cause of the greatest area burned. In both sub-regions, power line ignitions were one of the top two causes of area burned: the other major causes were arson in one sub-region and power equipment in the other. Equipment use also caused the largest number of fires in both sub-regions. These results have important implications for understanding why, where and how ignitions are caused, and in turn, how to develop strategies to prioritise and focus fire prevention efforts. Fire extent has increased tremendously in southern California, and because most fires are caused by humans, ignition reduction offers a potentially powerful management strategy, especially if optimised to reflect the distinct spatial and temporal distributions in different ignition causes.
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Plucinski, Matt P., e Wendy R. Anderson. "Laboratory determination of factors influencing successful point ignition in the litter layer of shrubland vegetation". International Journal of Wildland Fire 17, n. 5 (2008): 628. http://dx.doi.org/10.1071/wf07046.
Testo completoAbstract (sommario):
Factors affecting ignition thresholds of the litter layer of shrubland vegetation were investigated using reconstructed litter beds in a laboratory. The factors investigated were fuel moisture content (FMC), litter type (primarily species), pilot ignition source, and wind. Litter beds made from 11 different litter types were ignited with point ignition sources. Litter from Allocasuarina nana (Sieber ex Spreng.) L.A.S. Johnson was used as the standard type across all experiments. Successful ignition was defined as fire spreading a fixed distance from the ignition point. Ignition success was modelled as a logistic function of FMC. Litter type had a major effect on ignitibility. The bulk density of the litter bed and the surface area of litter per volume of litter bed provided reasonably good predictors of the effect of litter type on ignition success. Low-density litter beds ignited at higher FMCs than dense litter beds. The two densest litter beds failed to ignite with the procedures used here. The ignition sources tested had significantly different effects on ignition success. Larger ignition sources were able to ignite wetter fuels than smaller sources. The presence of wind was found to have a different effect on ignition success depending on the location of the ignition source with respect to the litter bed. Wind decreased ignition success when the ignition source was located on top of the litter bed, but aided ignition when the ignition source was located within the litter bed.
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Feng, Yan. "Reliability Analysis for the Ignition System of Aviation Piston Engine in the GO Methodology". Advanced Materials Research 1044-1045 (ottobre 2014): 375–79. http://dx.doi.org/10.4028/www.scientific.net/amr.1044-1045.375.
Testo completoAbstract (sommario):
Analyzing success probability of the ignition system of aviation piston engine based on GO methodology.Constructing the GO diagram of the ignition system of aviation piston engine and definites operational character types and fault rates.Using two quantification analysis methods without considering effects from the shared signal (signal generator 3),the success probabilities of the ignition system is 0.693. With considering effects from the shared signal (signal generator 3),the success probabilities of the ignition system is 0.707 by the corrected probability computing formula.so the effect from the shared signal should not be omitted.Using qualitative analysis method,the sum of the failure probability of minimal cut sets is0.780. After verification,the accuracy of reliability analysis for the ignition system using the corrected GO model with considering effects from shared signals is highest,and this GO model is applicable for reliabiliity analysis of the ignition system of aviation piston engine.
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Kun, Liu, Lu Tian, Lan Jian, Huang Xiaoyu e Yin Guofeng. "Experiment Study of Ignition Characteristics in An Axial-flow-injector Burner for Stirling Engine". E3S Web of Conferences 313 (2021): 11002. http://dx.doi.org/10.1051/e3sconf/202131311002.
Testo completoAbstract (sommario):
To investigate the ignition characteristics of an axial-flow injection burner for a Stirling engine, a combustion chamber was designed. Diesel was used as fuel and oxygen as oxidant. The experiments of ignition characteristics were carried out with an electric plug igniter. The ignition characteristics under different combustion chamber pressure, pre-oxygen supply time, oxygen supply flow and ignition position were studied. The experimental results show that, with the increase of the pressure, the ignition time of the burner increases gradually, and the ignition success rate decreases gradually. The oxygen flow rate is related to ignition time in a certain range, while the pre-oxygen supply time has little effect. With the ignition position moving downward, the ignition time decreases gradually.
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Tanskanen, Heidi, Ari Venäläinen, Pasi Puttonen e Anders Granström. "Impact of stand structure on surface fire ignition potential in Picea abies and Pinus sylvestris forests in southern Finland". Canadian Journal of Forest Research 35, n. 2 (1 febbraio 2005): 410–20. http://dx.doi.org/10.1139/x04-188.
Testo completoAbstract (sommario):
Forest fire ignition potential was investigated in Picea abies (L.) Karst. (Norway spruce) and Pinus sylvestris L. (Scots pine) dominated stands of 0, 15, 3045, and 4060 years of age. A series of small-scale (<0.5 m2) ignition tests were carried out in experimental plots on 61 different days in June, July, and August. Ignition success percentages were analyzed in relation to stand structural properties, preclassified stand types, and the output of the Canadian Fire Weather Index system. In addition, the number of average stand-type-specific fire days was estimated based on weather data (JuneAugust) for southern Finland for the years 19912002. Factors in stand structure that significantly correlated with the ignition success percentage were canopy depth and leaf area index, the correlation coefficients being 0.575 (p < 0.005) and 0.582 (p < 0.005), respectively. In Pinus sylvestris dominated stands, ignition tests produced self-sustained surface fires in 32.0%, 24.0%, and 19.3% of cases in 0-, 15-, and 30- to 45-year age classes, respectively. In Picea abies dominated sites conditions were favorable for fire in 12.0% and 4.6% of trials in the 0- and 40- to 60-year age classes, respectively. The output of the FWI-system correlated well with the ignition success in June and July but poorly in August. Based on the 12-year time series analysis, there were on average per year 27, 18, and 14 potential fire days in 0-, 15-, and 30- to 45-year-old Pinus sylvestris stands, and 10 and 4 potential fire days in 0- and 40- to 60-year-old Picea abies stands, respectively. We concluded that the dominance of Picea abies or Pinus sylvestris and stand age appear to modify the ignition conditions significantly and should be used as threshold indicators in fire occurrence predictions.
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Cardil, A., M. Lorente, D. Boucher, J. Boucher e S. Gauthier. "Factors influencing fire suppression success in the province of Quebec (Canada)". Canadian Journal of Forest Research 49, n. 5 (maggio 2019): 531–42. http://dx.doi.org/10.1139/cjfr-2018-0272.
Testo completoAbstract (sommario):
In the managed forest of Canada, forest fires are actively suppressed through efficient initial attack capability; however, the impact of different factors on the suppression success remains to be understood. The aim of this paper was to analyze the influence of operational suppression objectives (fire detection, initial attack, and fire control) along with fire intensity, fuel type, fire ignition cause, year, workload, and homogeneous fire regime zones on the achievement of the fire suppression objective (fire < 3 ha) using the Forest Fire Protection Agency of Quebec (SOPFEU) as a case study. The overall success of the suppression objective was very high (88%) over the study period (1994–2015). Both detection and control had significant effects on the suppression success through their interaction with fuel type, ignition cause, fire intensity, and zone variables. When the suppression objective was not achieved, final fire size was influenced by control, fuel type, fire intensity, and zone. The paper highlights the importance of the operational objectives and of regional differences for both fire suppression success and final fire size. Our results can help forest fire protection agencies to better understand their wildland fire suppression systems for a better adaptation to the upcoming fire regime changes.
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Li, Shuai, You Jun Zhang, Jun Hao, Wen Yu Gu e Yu Qi Lei. "Optimization of Fuel Injection Process and Structural Analysis". Journal of Physics: Conference Series 2717, n. 1 (1 marzo 2024): 012014. http://dx.doi.org/10.1088/1742-6596/2717/1/012014.
Testo completoAbstract (sommario):
Abstract In order to solve the problem of precise and controllable ignition fuel injection point in the process of UCG, this paper proposes a process method of presetting the ignition agent. The method achieves the purpose of improving the ignition success rate by increasing the downhole ambient temperature and reducing the ignition threshold. By simulating and analyzing the fluid properties of the fuel in the pipeline, the velocity and dynamic pressure at the outlet of the pipeline under different initial velocities are obtained. The results show that the outlet velocity, dynamic pressure and initial velocity have an irregular curvature relationship. As the initial velocity increases, the outlet velocity and dynamic pressure continue to increase. After calculation, the relationship between the exit speed (Y) and the initial speed (X) is Y=-0.5069X2+2.0909X+5.0624. Therefore, long-distance injection is not conducive to the successful ignition of the fuel downhole.
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Zhang, Tingliang, Hui Zhao, Lantao He e Tianyu Wang. "Study on the combustion process of the ramjet combustion chamber". Journal of Physics: Conference Series 2489, n. 1 (1 maggio 2023): 012010. http://dx.doi.org/10.1088/1742-6596/2489/1/012010.
Testo completoAbstract (sommario):
Abstract To explore the ignition performance of the ramjet combustion chamber, this paper combined the specific structure and working principle of the ramjet to model the ramjet combustion chamber, and carried out numerical simulation research on the flow field characteristics and combustion process of the stable operation of the combustion chamber. The results show that for the blunt-body of the flame stabilizer, the overall flame stability zone is relatively large at low inlet velocity, but the strength of the return zone at low inlet velocity is smaller than that at high speed. The flame stability zone formed at high inlet velocity is more stable and has stronger resistance to external disturbance. When the ratio of oil and gas mixtures is in the flammability limit range, the selection of ignition position has an important influence on the success of ignition. When the high-temperature zone formed by the initial ignition core can be diffused into the reflux zone and maintain sufficient temperature, the ignition can be successful.
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Yu, Dezhao, Jiale Yao, Jiafu Ma, Yangyang Hou, Shaoyun Zhang e Yusong Yu. "Experimental Study on the Influence of Microwave Energy Pulse Width and Duty Cycle on Evaporation and Ignition Characteristics of ADN-Based Liquid Propellant Droplets". Aerospace 11, n. 7 (12 luglio 2024): 573. http://dx.doi.org/10.3390/aerospace11070573.
Testo completoAbstract (sommario):
This study investigates the evaporation and ignition characteristics of a single droplet of ammonium dinitramide (ADN)-based liquid propellant utilizing a waveguide resonant cavity device, in conjunction with a high-speed photographic imaging system and testing system. Experimental methods are employed to analyze the impact of microwave pulse width and duty cycle on the puffing and meicro-explosion phenomena of the droplet, as well as the delay time and duration of ignition. The experimental findings reveal that increasing the duty cycle enhances the ignition success rate and diminishes flame development time. Specifically, elevating the microwave duty cycle from 60% to 80% reduces the ignition delay time of the droplet from 132.8 ms to 88.1 ms, and the ignition duration from 23.1 ms to 19.9 ms. Furthermore, an increase in microwave energy pulse width expedites the combustion process of the flame and influences plasma generation. Increasing the pulse width of microwave energy from 20 µs to 40 µs prolongs the ignition delay time from 140.3 ms to 200.5 ms and extends the ignition duration from 56.7 ms to 77.8 ms. Additionally, it is observed that a higher duty cycle leads to a more pronounced puffing phenomenon that initiates earlier. In contrast, a higher pulse width results in a more pronounced puffing phenomenon that commences later. This study provides a thorough investigation into the microwave ignition mechanism of ADN-based liquid propellants, offering theoretical insights into the ignition and combustion stability of such propellants in microwave-assisted ignition systems.
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Wandel, Andrew P. "Influence of scalar dissipation on flame success in turbulent sprays with spark ignition". Combustion and Flame 161, n. 10 (ottobre 2014): 2579–600. http://dx.doi.org/10.1016/j.combustflame.2014.04.006.
Testo completo
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Cary, Geoffrey J., Mike D. Flannigan, Robert E. Keane, Ross A. Bradstock, Ian D. Davies, James M. Lenihan, Chao Li, Kimberley A. Logan e Russell A. Parsons. "Relative importance of fuel management, ignition management and weather for area burned: evidence from five landscape - fire - succession models". International Journal of Wildland Fire 18, n. 2 (2009): 147. http://dx.doi.org/10.1071/wf07085.
Testo completoAbstract (sommario):
The behaviour of five landscape fire models (CAFÉ, FIRESCAPE, LAMOS(HS), LANDSUM and SEM-LAND) was compared in a standardised modelling experiment. The importance of fuel management approach, fuel management effort, ignition management effort and weather in determining variation in area burned and number of edge pixels burned (a measure of potential impact on assets adjacent to fire-prone landscapes) was quantified for a standardised modelling landscape. Importance was measured as the proportion of variation in area or edge pixels burned explained by each factor and all interactions among them. Weather and ignition management were consistently more important for explaining variation in area burned than fuel management approach and effort, which were found to be statistically unimportant. For the number of edge pixels burned, weather and ignition management were generally more important than fuel management approach and effort. Increased ignition management effort resulted in decreased area burned in all models and decreased number of edge pixels burned in three models. The findings demonstrate that year-to-year variation in weather and the success of ignition management consistently prevail over the effects of fuel management on area burned in a range of modelled ecosystems.
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Wang, Haihui, Bangxin Jin, Kaixuan Zhang, Shamima Aktar e Zhilong Song. "Effectiveness in Mitigating Forest Fire Ignition Sources: A Statistical Study Based on Fire Occurrence Data in China". Fire 5, n. 6 (14 dicembre 2022): 215. http://dx.doi.org/10.3390/fire5060215.
Testo completoAbstract (sommario):
Control of forest fire ignition sources is the top priority in fire management practices. China has gained great success in reducing forest fires in recent years, and the relevant safety measures taken during this process are worthy of investigation and publicity. Based on fire statistical data through the years between 2003 and 2017, we analyzed the detailed classification of fire ignition sources and their contribution to the annual forest fire occurrence. The role of different ignition sources in altering fire occurrence was quantified and ranked by defining a contribution extent parameter. A statistical tool was also applied to conduct correlation analysis to identify variation patterns of time series data from individual fire causes. The annual fire numbers declined after 2008 and stabilized at a level < 2000 in recent years, pointing to the containment of several major ignition sources. Starting from the legislative development, an accountability system was established at all levels from administrative heads to local residents, paving the way for the multifaceted and full-coverage fire prevention publicity and education as well as the fire use restriction in particular seasons. The effectiveness of management measures in lessening forest fire occurrence was interpreted using the results of correlation analysis among the fire numbers initiated by individual ignition sources.
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Huang, Siyuan, James J. Sheng, Qi Jiang e Jiali Liu. "Screening of Spontaneous Ignition Feasibility During Air Injection EOR Process Based on Thermal Experiments". Energies 12, n. 19 (26 settembre 2019): 3687. http://dx.doi.org/10.3390/en12193687.
Testo completoAbstract (sommario):
The feasibility of spontaneous ignition is extremely important to the success of AIP (air injection process) projects. However, no laboratory experiments were reported on the detection of crude oil spontaneous ignition during AIP. The initial intention of the thermal experiments is to screen candidate oil reservoirs for the application of AIP in a faster and less expensive way than combustion tube tests. However, instead of performing a feasibility study, most of the research only employed thermal experiments as a tool to obtain kinetic data and to characterize the thermal-oxidative behavior for different crude oil samples. The question of how to use the thermal experiments to determine the feasibility of spontaneous ignition has not been answered yet. This study proposes a practical method to investigate the spontaneous ignition feasibility during AIP, which directly relates the oil reactivity and reservoir properties. An example of the application of this method was presented in this paper, where a mixture of a light oil and sand was tested by the TGA and DSC to obtain the kinetic data and net heat. The obtained parameters were then used to evaluate the feasibility of spontaneous ignition. The results showed that the tested oil and sand mixture cannot lead to spontaneous ignition due to crude oil’s insufficient reactivity. Furthermore, the typical crude oil kinetic data and reservoir conditions were used to investigate the screening criteria for spontaneous ignition. The results indicated that the crude oil’s activation energy and frequency factor need to be less than 60 kJ/mole and higher than 2 s−1, respectively, in order to satisfy the need of spontaneous ignition.
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Hollis, J. J., W. L. McCaw e M. G. Cruz. "The effect of woody fuel characteristics on fuel ignition and consumption: a case study from a eucalypt forest in south-west Western Australia". International Journal of Wildland Fire 27, n. 5 (2018): 363. http://dx.doi.org/10.1071/wf17174.
Testo completoAbstract (sommario):
Coarse woody debris (>0.6 cm in diameter) is an important component of the fuel complex in Australian eucalypt forests, influencing both fire behaviour, smoke production and post-fire ecological processes. We investigated how physical characteristics of woody fuel affected ignition and consumption during an experimental fire where the fuel complex characteristics, fire weather and fire behaviour varied within a narrow range. Decay status, bark condition, arrangement, suspension and extent of charring were classified for 2866 coarse woody fuel particles. We used generalised linear model (GLM) analysis to explain ignition success and the extent of consumption of individual particles, with a focus on larger diameter fuels (>7.5 cm in diameter), which comprised 83% of the woody fuel load and 94% of the woody fuel consumed during the flaming and smouldering stages of combustion. Ignition success was best explained by a model that included fuel arrangement (a surrogate of fuel proximity), suspension and decay status. The extent of fuel consumption was greater for pieces in advanced stages of decay, but suspension (inversely related) and arrangement (directly related) also affected the outcome. Forest management practices, previous fire history and other natural disturbances are likely to influence the distribution of pre-fire diameters and suspension classes that characterise large woody fuels at a site, and will therefore influence woody fuel consumption. This has practical implications for quantifying heat release and atmospheric emissions from fires burning in forests with different management histories.
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Hollis, J. J., W. L. McCaw e M. G. Cruz. "Corrigendum to: The effect of woody fuel characteristics on fuel ignition and consumption: a case study from a eucalypt forest in south-west Western Australia". International Journal of Wildland Fire 28, n. 8 (2019): 640. http://dx.doi.org/10.1071/wf17174_co.
Testo completoAbstract (sommario):
Coarse woody debris (>0.6cm in diameter) is an important component of the fuel complex in Australian eucalypt forests, influencing both fire behaviour, smoke production and post-fire ecological processes. We investigated how physical characteristics of woody fuel affected ignition and consumption during an experimental fire where the fuel complex characteristics, fire weather and fire behaviour varied within a narrow range. Decay status, bark condition, arrangement, suspension and extent of charring were classified for 2866 coarse woody fuel particles. We used generalised linear model (GLM) analysis to explain ignition success and the extent of consumption of individual particles, with a focus on larger diameter fuels (>7.5cm in diameter), which comprised 83% of the woody fuel load and 94% of the woody fuel consumed during the flaming and smouldering stages of combustion. Ignition success was best explained by a model that included fuel arrangement (a surrogate of fuel proximity), suspension and decay status. The extent of fuel consumption was greater for pieces in advanced stages of decay, but suspension (inversely related) and arrangement (directly related) also affected the outcome. Forest management practices, previous fire history and other natural disturbances are likely to influence the distribution of pre-fire diameters and suspension classes that characterise large woody fuels at a site, and will therefore influence woody fuel consumption. This has practical implications for quantifying heat release and atmospheric emissions from fires burning in forests with different management histories.
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Cawson, Jane G., e Thomas J. Duff. "Forest fuel bed ignitability under marginal fire weather conditions in Eucalyptus forests". International Journal of Wildland Fire 28, n. 3 (2019): 198. http://dx.doi.org/10.1071/wf18070.
Testo completoAbstract (sommario):
Fires burning under marginal fire-weather conditions tend to be patchy in terms of their spatial coverage. This patchiness is partially driven by variability in the ignitability of the fuel bed. An understanding of fuel-bed ignitability through space and time would help fire managers to more effectively carry out prescribed burns to achieve desired levels of burn coverage in Eucalyptus forests. We sought to identify the key fuel-bed attributes influencing ignitability under marginal weather conditions. We recorded ignition successes and failures at 45 points within 5 operational prescribed burns and used the data to build logistic regression models to predict the probability of ignition as a function of fuel-bed attributes. Models were ranked using an information theoretic approach. The four highest ranked models explained 48–54% of the variance in ignitability. Surface fine-fuel moisture content (FFMC) and overall fuel hazard (i.e. fuel arrangement) were the strongest predictors of ignitability, occurring in all four highest ranking models. Both surface FFMC and overall fuel hazard were negatively related to ignition likelihood, contradicting a commonly assumed positive relationship between fuel hazard and flammability. Our field method to measure ignition success could be applied across more prescribed burns to develop operationally useful models of ignitability.
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Sullivan, Vickie. "Alexander the Great as “Lord of Asia” and Rome as His Successor in Machiavelli's Prince". Review of Politics 75, n. 4 (2013): 515–37. http://dx.doi.org/10.1017/s0034670513000569.
Testo completoAbstract (sommario):
AbstractAlexander the Great and his legacy suffuse The Prince, a fact that has received little attention. Machiavelli uses Alexander to illustrate the form of rule in which one is lord and all others are slaves. In recounting the Roman Republic's conquest of Greece, Machiavelli treats Alexander's vanquished successors. Alexander's legacy enters Rome itself, igniting in Romans the desire to subject the world to sole preeminence. According to Machiavelli, Caesar imitated Alexander, and Caesar overturned the republic, initiating the rule of one in Rome. Caesar had his own Roman successors, the emperors who ruled under his name. Rome succeeded in imposing the rule of one on Europe. That form of rule exists in Machiavelli's times with the states of the Turk and the Sultan as well as with the papacy in a limited respect. Something of the old Rome and its Alexandrian aspirations persists in Christian Rome.
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Zhang, Jia Ming, Xiao Dong Wu, Shu Dong Li, Jia Zhang, Han Han Zhang, Bei Lin Qi e Zi Yao Zhong. "Utilizing of In Situ Combustion Process in Xinjiang Oil Field through Analysis of Produced Fluids". Advanced Materials Research 772 (settembre 2013): 751–54. http://dx.doi.org/10.4028/www.scientific.net/amr.772.751.
Testo completoAbstract (sommario):
The tests of domestic In-Situ Combustion began in 1960s, with smaller and slower development. The technology has been further developed in recent years. There are five pilot projects, which increase more than 60,000 tons of crude oil. X block of Xinjiang Oil Field has been ignited since December of 2009. With the development of the In-situ Combustion technology, the use of analysis of produced fluids is very necessary, which provide theoretical basis for the commencement of the next steps. We can draw conclusion through the analysis of produced fluids: the success of ignition; the adequacy of combustion; reactions at high temperature or low temperature; the forward direction and location of fire front. Analysis of produced fluids for Xinjiang Oil Field determine clearly the ignition is successful and the way forward of the fire-drive front.
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Yao, Qikai. "The challenges of nuclear fusion reactor". Theoretical and Natural Science 11, n. 1 (17 novembre 2023): 105–10. http://dx.doi.org/10.54254/2753-8818/11/20230387.
Testo completoAbstract (sommario):
Energy shortage is one of nonnegligible problems nowadays. Even since the twenty centuries, the achievement of fission reactor has proved that nuclear energy is a powerful source. However, fission reaction could cause radiation hazard if operation error happens. Nuclear fusion can provide more clean energy. This paper discusses nuclear fusion and two typical models of fusion reactor, inertial confinement fusion reactor and tokamak, and their properties. Fusion reactors use deuterium and tritium to fuse heavier nucleus and release energy. With -distribution, deuterium-tritium fusion reactivity can be boosted at relatively low temperature. Furthermore, fusion reactor has initial success. The more energy can be created than energy used to ignition. To solve nuclear fuel problem, continue ignition progress problem, possibly achieving controllable fusion reaction. The improvements which this paper mentioned perhaps allow to extend the application context of fusion reactor.
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Fang, K., Y. H. Zhang, Y. F. Dong, T. H. Zhang, Z. Zhang, X. H. Yuan, Y. T. Li e J. Zhang. "Dynamical process in the stagnation stage of the double-cone ignition scheme". Physics of Plasmas 30, n. 4 (aprile 2023): 042705. http://dx.doi.org/10.1063/5.0139659.
Testo completoAbstract (sommario):
In the double-cone ignition scheme, two deuterium–tritium shells in a pair of head-on Au cones are compressed and accelerated spherically [Zhang et al., Philos. Trans. R. Soc. A. 378 (2184), 20200015 (2020)]. The high-speed plasma jets from the cone tips collide and form a stagnating plasma with a higher density during the stagnation stage, preheating the plasma by the Coulomb potential. The preheated plasma is then rapidly heated up further to the ignition temperature by fast electrons generated by a powerful laser pulse of 10 ps. The conditions of the stagnating plasma strongly affect the fast-heating efficiency and consequently the success of ignition. In order to understand dynamical process in the stagnation stage, a special experimental campaign was conducted, where the evolution of the stagnating plasma was diagnosed through the temporal resolved self-emission signals. The spatial-temporal distributions of temperature and density of the colliding plasma were analyzed by the Abel inversion algorithm and the Legendre polynomial fitting. The stagnation period was found to be about 300 ps, the temperature of the core area of the stagnated plasma was between 340 and 390 eV, while the aspect ratio of the colliding plasma was about 0.78.
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Fossi, Alain, e Alain DeChamplain. "Large eddy simulation of spark ignition of a bluff-body stabilized burner using a subgrid-ignition model coupled with FGM-based combustion models". International Journal of Numerical Methods for Heat & Fluid Flow 27, n. 2 (6 febbraio 2017): 400–427. http://dx.doi.org/10.1108/hff-07-2015-0299.
Testo completoAbstract (sommario):
Purpose Safety improvement and pollutant reduction in many practical combustion systems and especially in aero-gas turbine engines require an adequate understanding of flame ignition and stabilization mechanisms. Improved software and hardware have opened up greater possibilities for translating basic knowledge and the results of experiments into better designs. The present study deals with the large eddy simulation (LES) of an ignition sequence in a conical shaped bluff-body stabilized burner involving a turbulent non-premixed flame. The purpose of this paper is to investigate the impact of spark location on ignition success. Particular attention is paid to the ease of handling of the numerical tool, the computational cost and the accuracy of the results. Design/methodology/approach The discrete particle ignition kernel (DPIK) model is used to capture the ignition kernel dynamics in its early stage of growth after the breakdown period. The ignition model is coupled with two combustion models based on the mixture fraction-progress variable formulation. An infinitely fast chemistry assumption is first done, and the turbulent fluctuations of the progress variable are captured with a bimodal probability density function (PDF) in the line of the Bray–Moss–Libby (BML) model. Thereafter, a finite rate chemistry assumption is considered through the flamelet-generated manifold (FGM) method. In these two assumptions, the classical beta-PDF is used to model the temporal fluctuations of the mixture fraction in the turbulent flow. To model subgrid scale stresses and residual scalars fluxes, the wall-adapting local eddy (WALE) and the eddy diffusivity models are, respectively, used under the low-Mach number assumption. Findings Numerical results of velocity and mixing fields, as well as the ignition sequences, are validated through a comparison with their experimental counterparts. It is found that by coupling the DPIK model with each of the two combustion models implemented in a LES-based solver, the ignition event is reasonably predicted with further improvements provided by the finite rate chemistry assumption. Finally, the spark locations most likely to lead to a complete ignition of the burner are found to be around the shear layer delimiting the central recirculation zone, owing to the presence of a mixture within flammability limits. Research limitations/implications Some discrepancies are found in the radial profiles of the radial velocity and consequently in those of the mixture fraction, owing to a mismatch of the radial velocity at the inlet section of the computational domain. Also, unlike FGM methods, the BML model predicts the overall ignition earlier than suggested by the experiment; this may be related to the overestimation of the reaction rate, especially in the zones such as flame holder wakes which feature high strain rate due to fuel-air mixing. Practical implications This work is adding a contribution for ignition modeling, which is a crucial issue in various combustion systems and especially in aircraft engines. The exclusive use of a commercial computational fluid dynamics (CFD) code widely used by combustion system manufacturers allows a direct application of this simulation approach to other configurations while keeping computing costs at an affordable level. Originality/value This study provides a robust and simple way to address some ignition issues in various spark ignition-based engines, namely, the optimization of engines ignition with affordable computational costs. Based on the promising results obtained in the current work, it would be relevant to extend this simulation approach to spray combustion that is required for aircraft engines because of storage volume constraints. From this standpoint, the simulation approach formulated in the present work is useful to engineers interested in optimizing the engines ignition at the design stage.
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Lee, Chong-Won, Yun-Sik Han e Jong-Po Park. "Use of Directional Spectra for Detection of Engine Cylinder Power Fault". Shock and Vibration 4, n. 5-6 (1997): 391–401. http://dx.doi.org/10.1155/1997/307013.
Testo completoAbstract (sommario):
A diagnostic method, which uses the two-sided directional power spectra of complex-valued engine vibration signals, is presented and tested with four-cylinder compression and spark ignition engines for the diagnosis of cylinder power faults. As spectral estimators, the maximum likelihood and FFT methods are compared, and the multi-layer neural network is employed for pattern recognition. Experimental results show that the success rate for identifying the misfired cylinder is much higher with the use of two-sided directional power spectra than conventional one-sided power spectra.
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Palanti, Lorenzo, Antonio Andreini e Bruno Facchini. "Numerical prediction of the ignition probability of a lean spray burner". International Journal of Spray and Combustion Dynamics 13, n. 1-2 (giugno 2021): 96–109. http://dx.doi.org/10.1177/17568277211012536.
Testo completoAbstract (sommario):
The optimization of the igniter position is a critical issue in modern aviation gas turbines since it can help to minimize the amount of energy required for ignition and to guarantee a fast relight in case of flameout. From a numerical perspective, several spark discharges should be simulated for each spark position, to account for different realizations due to time-dependent turbulent motions. Unfortunately, standard simulations are impractical to use for this purpose, due to the need of carrying out several unsteady simulations, leading to a huge associated computational effort. This is why low-order models have been developed, providing an affordable estimation of the local ignition probability, by sacrificing the accuracy and the physical consistency of the prediction. In the present work, a previously developed low-order design model has been implemented in ANSYS Fluent 2019R1® and used to investigate the ignition performance of a single-sector, confined spray flame, where data from laser ignition experiments are available. A non-reactive Large Eddy Simulation, which is validated against experimental data, provides the base flow needed to feed the model. If the tuning parameters of the ignition model are well calibrated, it provides quite good results. In the test case here investigated, it is shown that ignition is possible in the outer recirculation zone and very unlikely elsewhere. Later, a discussion about the effect of the most relevant tuning parameters is carried out. It is shown that the model mostly succeed to identify the area of possible ignition, even if the lack of calibration could lead to a poorer agreement with the experimental data.
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Amann, C. A. "Past Experiences With Automotive External Combustion Engines". Journal of Engineering for Gas Turbines and Power 121, n. 3 (1 luglio 1999): 546–50. http://dx.doi.org/10.1115/1.2818507.
Testo completoAbstract (sommario):
GMR (General Motors Research Laboratories, now GM R&D Center) has a history of improving the internal combustion engine, especially as it relates to automotive use. During the quarter century from 1950–75, considerable effort was devoted to evaluating alternative powerplants based on thermodynamic cycles different from those on which the established spark-ignition and diesel engines are founded. Two of these, the steam engine and the Stirling engine, incorporated external combustion. Research on those two alternatives is reviewed. Both were judged to fall short of current needs for commercial success as prime movers for conventional automotive vehicles.
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Sumar Hadi Suryo. "Atmega328p microcontroller based biometric starting system design for caterpillar D3k dozer heavy operators". GSC Advanced Research and Reviews 13, n. 1 (30 ottobre 2022): 001–6. http://dx.doi.org/10.30574/gscarr.2022.13.1.0251.
Testo completoAbstract (sommario):
Heavy equipment industry is an employment sector with potentially high rate of accidents, which might occur due to the operator's own fault, where he or she does not have competence in operating such an equipment. This operator's fault accident ranks number two after that of the mechanic's accident rate, which is the focus of this research. In line with the latest digital electronic development, companies have been able to solve problems confronted with operators, one of which is through the application of biometric authorization device, which has been expected to be able to reduce the rate in the industrial accidents in heavy equipment rental. This device works by requiring authorization of the operator without inserting the manually inserted ignition key to the machine, but the operator's fingerprint that has been authorized into the system to operate such a machine. This, in turn, Will be able to reduce risks of getting an accident among operators. Fingerprint has its function to recognize the operator's identity as well as password to the electronic Ignition key to the machine that not everybody can get access to operating the machine to start it up. Design of this electronically control device is to produce biometrically engine start-up replacing the currently recognize Ignition switch to crank and switch off the engine using microcontroller ATmega328P system. Results of the study gained from the tests based on the standard operating procedures show based on the standard Operating procedures show a 100% success without any obstacles.
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Balbi, J. H., P. A. Santoni e J. L. Dupuy. "Dynamic modelling of fire spread across a fuel bed". International Journal of Wildland Fire 9, n. 4 (1999): 275. http://dx.doi.org/10.1071/wf00005.
Testo completoAbstract (sommario):
The analysis of laboratory fire experiments led to the development of a reaction-diffusion model for the spread of fire across a fuel bed in windless and slopeless conditions. A method for the determination of coefficients in this model based on the dynamic features of a spreading fire is given. The numerical study of the mathematical problem proposed allows us to predict the rate of spread, the fire front perimeter and the temperature distribution for line-ignition and point-ignition fires. These results are compared with success to experimental data. Furthermore, the model allows us to estimate the acceleration of spread for a point-ignition fire in its initial stage and in the steady-state phase. Résumé Une analyse menée sur des expériences de laboratoires nous a permis de proposer un modèle de réaction-diffussion pour la propagation du feu sans vent et sans pente au travers d’une litière. Une méthode d’identification des coefficients du modèle, à partir des caractéristiques dynamiques de la propagation du feu, est donnée. L’étude numérique du problème mathématique nous permet de prédire la vitesse de propagation, le périmètre du front de feu et la température dans le domaine d’étude pour des allumages en ligne et pour des allumages ponctuels. Ces résultats sont comparés avec succés à des données expérimentales. De plus, nous sommes aussi en mesure de décrire l’accélération du front de feu dans les premiers instants suivant un allumage ponctuel.
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Irimescu, Adrian, Simona Silvia Merola e Bianca Maria Vaglieco. "Algorithm for Cycle-to-Cycle Firing TDC Identification Based on Wasted Spark Duration Measurements in Small Engines". Applied Sciences 13, n. 3 (19 gennaio 2023): 1362. http://dx.doi.org/10.3390/app13031362.
Testo completoAbstract (sommario):
Spark ignition (SI) engines are often used as distributed power generation applications. They ensure quick deployment, cost effective electricity, and are a valid choice for back-up power. An essential aspect for small size engines is to improve control margins without increasing the number of sensors. It is not uncommon to employ fixed ignition timing for such power units, with so called wasted spark systems. These feature two spark events per cycle, one during compression and one during the exhaust stroke. On the other hand, ever more complex control systems are applied for this engine category in the search for better efficiency and lower emissions. Control of actuators that is phased with the working cycle could represent a significant advantage in this context. A method previously developed for identifying top dead center (TDC) phasing offline was applied as an algorithm capable of performing the required task while the engine is running. It is based on current measurements in the secondary ignition circuit of systems that feature wasted spark operation. Validation was performed on a 50 cm3 SI unit connected to a 1 kW power generator. Statistical distribution during sequences of 1000 cycles recorded at five different levels of load was used for testing TDC identification capabilities. Results were also compared to evaluations based on engine speed measurements. The overall TDC identification success rate of the proposed algorithm was found to be over 99.8%.
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Wulfert, Tobias, e Benjamin Dennhardt. "Establishing successful e-commerce ecosystems: Evaluating strategies for reaching a critical mass of participants". Corporate Ownership and Control 20, n. 3 (2023): 130–45. http://dx.doi.org/10.22495/cocv20i3art9.
Testo completoAbstract (sommario):
Although e-commerce in general and platform business models in e-commerce report steadily increasing revenues, establishing e-commerce ecosystems is not a guaranteed success per se. Potential platform owners must carefully plan the ignition of the ecosystem to reach a critical mass of customers. This critical mass is crucial for the platform to benefit from direct and indirect network effects. However, research so far has not provided clear guidance and strategies on how to successfully establish ecosystems in e-commerce. Therefore, we evaluated and demonstrated generic platform ignition strategies in e-commerce. Our evaluation is thereby based upon an established mathematical model for two-sided markets considering utility gains from indirect network effects and costs. The heterogeneity of the individual market sides is reflected in the form of sigmoidal distribution functions. Applying this model, we show that subsidies, seeding, marquee, single side, micro market, piggybacking, opening up, and big bang marketing are potential strategies for reaching a critical mass of participants in e-commerce ecosystems. We provide guidance for practitioners on how to establish successful e-commerce ecosystems. We contribute to the body of knowledge strategies in e-commerce ecosystems by bridging critical mass and network effects.
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Bermúdez, Vicente, Vicente Macián, David Villalta e Lian Soto. "Impact of injection settings on gaseous emissions and particle size distribution in the dual-mode dual-fuel concept". International Journal of Engine Research 21, n. 4 (24 aprile 2019): 561–77. http://dx.doi.org/10.1177/1468087419844413.
Testo completoAbstract (sommario):
Reactivity controlled compression ignition concept has been highlighted among the low temperature combustion strategies. However, this combustion strategy presents some problems related to high levels of hydrocarbon and carbon monoxide emissions at low load and high-pressure rise rate at high load. Therefore, to diminish these limitations, the dual-mode dual-fuel concept has been presented as an excellent alternative. This concept uses two fuels of different reactivity and switches from a dual-fuel fully premixed strategy (based on the reactivity controlled compression ignition concept) during low load to a diffusive nature during high load operation. However, the success of dual-mode dual-fuel concept depends to a large extent on the low reactivity/high reactivity fuel ratio and the injection settings. In this study, parametric variations of injection pressure and injection timing were experimentally performed to analyze the effect over each combustion process that encompasses the dual-mode dual-fuel concept and its consequent impact on gaseous and particles emissions, including an analysis of particle size distribution. The experimental results confirm how the use of an adequate injection strategy is indispensable to obtain low exhaust emission and a balance between the different pollutants. In the fully premixed reactivity controlled compression ignition strategy, the particles concentrations were dominated by nucleation mode; however, the increase in injection pressure and the advance of the diesel main injection timing provided a simultaneous reduction of nitrogen oxide and solid particles (accumulation mode). During the highly premixed reactivity controlled compression ignition strategy, the accumulation-mode particles increased, and their concentrations were higher when the diesel main injection timing advanced and injection pressure decreased, as well as there was a slight increase in nitrogen oxide emissions. Finally, in the dual-fuel diffusion strategy, the concentrations of accumulation-mode particles were higher and there was a considerable increase of these particles with the advance of the diesel main injection timing and the reduction of the injection pressure, while the nitrogen oxide emissions decreased.
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Li, Q., PJ Shayler, M. McGhee e A. La Rocca. "The initiation and development of combustion under cold idling conditions using a glow plug in diesel engines". International Journal of Engine Research 18, n. 3 (28 luglio 2016): 240–55. http://dx.doi.org/10.1177/1468087416652266.
Testo completoAbstract (sommario):
Factors determining the success or failure of combustion initiation using a glow plug have been investigated through experimental work on a single cylinder, common rail diesel engine with a geometric compression ratio of 15.5, and a quiescent combustion bomb with optical access. A glow plug was required to avoid engine misfires when bulk gas temperature at the start of injection was less than 413 °C. The distance between the glow plug and the spray edge, the glow plug temperature, and the bulk gas temperature were important factors in meeting two requirements for successful ignition: a minimum local temperature of 413 °C and a minimum air/fuel vapour equivalence ratio of 0.15–0.35.
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LEJDA, Kazimierz. "Injection systems of high-speed diesel engines and development trends". Combustion Engines 123, n. 4 (1 novembre 2005): 19–30. http://dx.doi.org/10.19206/ce-117366.
Testo completoAbstract (sommario):
Current development of automotive industry is conditioned by the minimization of negative effects in relation to the environment. It results from the restrictions regarding exhaust emission limits which are introduced by the consecutive standards but it also guarantees market success of a given vehicle. Research carried out regarding customer preferences in UE countries have confirmed that during the purchase of a car they make decisions based on vehicle’s ecological properties and the safety of use in road conditions. Next such criteria follow as performance and durability which has so far been dominant. The analysis of the development trends of internal combustion engines clearly shows that the dominant engines are direct injection compression-ignition VGT engines. These engines have better work indices, significant values of total efficiency and most favorable ecological properties as opposed to spark-ignition engine. The obtainment of desirable utilization indices by diesel engine depends to a high degree from the injection systems applied in these engines. In the article characteristics of injection systems which are fitted in modern high-speed diesel engines as prime vehicle drive unit have been discussed. Systems with distributor injection pumps, with individual injection units and with pressure accumulators have too been presented. The requirements from injection systems have been qualified herein.
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Schaub, F. S., e R. L. Hubbard. "A Procedure for Calculating Fuel Gas Blend Knock Rating for Large-Bore Gas Engines and Predicting Engine Operation". Journal of Engineering for Gas Turbines and Power 107, n. 4 (1 ottobre 1985): 922–30. http://dx.doi.org/10.1115/1.3239837.
Testo completoAbstract (sommario):
This paper describes the procedure developed by Cooper-Bessemer for large-bore gas engines to calculate the knock rating of gas fuel blends and to predict with accuracy the required engine build to use that fuel with optimum detonation margin. Engine prototype test work has included fuel sensitivity tests mapped as a function of compression ratio, fuel air ratio, ignition advance, combustion air temperature, and engine rating. Success in predicting production engine operation for a given application involving a particular fuel blend has been gratifying. The basic reference method blend selected was normal butane in methane. Details are included in the paper to illustrate the problems in making sensitivity correlations between small-bore fuel research engines and large-bore production engines.
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Ratsimba, Harifidy Rakoto, Joary Niaina Andriamiharimanana, Michaela Braun e Johann Georg Goldammer. "Agricultural fuelbreaks in sustainable fire-resilient landscapes in Madagascar". Tropical Forest Issues, n. 61 (10 novembre 2022): 154–61. http://dx.doi.org/10.55515/pjmx6791.
Testo completoAbstract (sommario):
The first 65 km of agricultural fuelbreaks in the country were established in Boeny Region, northwestern Madagascar in 2021 and 2022. Mostly in grassy savanna, these fuelbreaks limit the spread of fires, and have also create an additional 615 ha of farmland for crop production. This should reduce the cleating in the national park and so reduce future fire ignitions. Due to the benefits seen by local smallholders and decision makers, their use has already spread to more locations. The keys to success are territorial land-use plans that make it possible to create fire-resistant mosaic landscapes that combine forest and agricultural land. The goal is to find sustainable solutions to the problem of fire, while in parallel, creating agricultural, economic and social opportunities.
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Li, Hailin, e Ghazi A. Karim. "Hydrogen Fueled Spark-Ignition Engines Predictive and Experimental Performance". Journal of Engineering for Gas Turbines and Power 128, n. 1 (23 luglio 2004): 230–36. http://dx.doi.org/10.1115/1.2055987.
Testo completoAbstract (sommario):
Hydrogen is well recognized as a suitable fuel for spark-ignition engine applications that has many unique attractive features and limitations. It is a fuel that can continue potentially to meet the ever-increasingly stringent regulations for exhaust and greenhouse gas emissions. The application of hydrogen as an engine fuel has been tried over many decades by numerous investigators with varying degrees of success. However, the performance data reported often tend not to display consistent agreement between the various investigators, mainly because of the wide differences in engine type, size, operating conditions used, and the differing criteria employed to judge whether knock is taking place or not. With the ever-increasing interest in hydrogen as an engine fuel, there is a need to be able to model extensively various features of the performance of spark ignition (S.I.) hydrogen engines so as to investigate and compare reliably the performance of widely different engines under a wide variety of operating conditions. In the paper we employ a quasidimensional two-zone model for the operation of S.I. engines when fueled with hydrogen. In this approach, the engine combustion chamber at any instant of time during combustion is considered to be divided into two temporally varying zones: a burned zone and an unburned zone. The model incorporates a detailed chemical kinetic model scheme of 30 reaction steps and 12 species, to simulate the oxidation reactions of hydrogen in air. A knock prediction model, developed previously for S.I. methane-hydrogen fueled engine applications was extended to consider operation on hydrogen. The effects of changes in operating conditions, including a very wide range of variations in the equivalence ratio on the onset of knock and its intensity, combustion duration, power, efficiency, and operational limits were investigated. The results of this predictive approach were shown to validate well against the corresponding experimental results, obtained mostly in a variable compression ratio CFR engine. On this basis, the effects of changes in some of the key operational engine variables, such as compression ratio, intake temperature, and spark timing are presented and discussed. Some guidelines for superior knock-free operation of engines on hydrogen are also made.
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Dean, Stephen O. "Beyond the physics and demonstration of ignition". Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 378, n. 2184 (12 ottobre 2020): 20200007. http://dx.doi.org/10.1098/rsta.2020.0007.
Testo completoAbstract (sommario):
Fusion holds the promise of providing growing world energy demand with a carbon-free power source having a universally available fuel source and attractive safety and environmental characteristics. A significant global effort has been underway for over 50 years aimed at the achievement of fusion by inertial confinement. The effort to date has necessarily emphasized understanding the physics of compressing and heating a small amount of fusion fuel to the high densities and temperatures required for ignition and energy gain. Though steady progress has been and is still being made to achieve the required physics understanding and energy gain, those goals have not yet quite been met. It is timely to put progress toward fusion power by inertial confinement into perspective by developing an updated roadmap. Preparing a roadmap from present achievements to the ultimate goal of commercial fusion power requires formally identifying and implementing complementary efforts on a number of fronts. These include the choice, development and demonstration of high repetition rate compression drivers (e.g. lasers) to succeed present day single-pulse sources; design, fabrication and testing of high gain targets (gain of order 100); development of mass production, cost-effective, target fabrication and delivery systems capable of inserting targets into the reaction chamber several times per second, and demonstrating ability to accurately hit and efficiently compress those targets to reliably produce the required fusion yields; design and demonstration of reaction chambers capable of handling energy yields and target debris clearing at the levels required for achieving high power plant reliability with low induced radioactivity. A robust ongoing effort on competitive power plant conceptual design is necessary to guide the implementation of a roadmap, including the timing and level of effort on the ‘beyond ignition’ demonstrations. This article is part of a discussion meeting issue ‘Prospects for high gain inertial fusion energy (part 1)’.