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利用Venn图巧记概率的运算公式 预览
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作者 夏天 《科教导刊》 2019年第4期41-42,共2页
概率的运算公式比较多,难以记住。本文介绍利用Venn图,来记住一些常用的概率的运算公式,其方法简单直观,易于掌握。
关键词 概率 Venn图 概率的运算公式
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指标验证的不确定度评定方法探讨 预览
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作者 李升春 梁琼崇 《电子产品可靠性与环境试验》 2019年第1期53-56,共4页
针对目前项目结题验证中最大允许误差指标与验证测试扩展不确定的转换需求,提出了3种不同的转换方法,并分别给出了3种转换方法的具体计算方法。通过比较分析,认为采用等值区间转换和等值方差转换不尽合理,因为在不同的分布下,测量结果... 针对目前项目结题验证中最大允许误差指标与验证测试扩展不确定的转换需求,提出了3种不同的转换方法,并分别给出了3种转换方法的具体计算方法。通过比较分析,认为采用等值区间转换和等值方差转换不尽合理,因为在不同的分布下,测量结果的包含概率不同,也就是说测量结果的可靠性会不同,这不符合项目指标要求的初衷,因此建议采用等概率指标转换法。 展开更多
关键词 不确定度 概率 等区间转换 等方差转换 等概率转换
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Erosion probability model of base-soil particle migration into agranular lter under local ow 预览
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作者 Yuan Wei Mei-li Zhan +3 位作者 Qing-fu Huang Jin-chang Sheng Yulong Luo Qing Zhou 《国际泥沙研究:英文版》 SCIE 2019年第5期455-460,共6页
To avoid soil erosion, lters often are installed in the downstream cross section of dams. However, the probability of piping failure and the lter effect both are related to the soil pore network. Previous erosion prob... To avoid soil erosion, lters often are installed in the downstream cross section of dams. However, the probability of piping failure and the lter effect both are related to the soil pore network. Previous erosion probability models for a base soil- lter system do not consider the effect of local ow. Therefore, in this study, an improved erosion probability model is established, in which the deviation between the main ow direction of the soil and the local ow direction in the lter was considered based on a previous model. The improved model was validated by numerical simulation. The erosion probability was found to affect the reasonable evaluation of lter effects and the optimal selection of lter thickness. The controlling con- striction size in a granular lter was increased to Dc* Dc5 with a lter thickness of 59 Dm. 展开更多
关键词 GRANULAR filter PORE network EROSION PROBABILITY LOCAL flow Deviation PROBABILITY
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Analysis of Coverage and Area Spectrum Efficiency of UDN with Inter-Tier Dependence 预览
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作者 Kaichuang Wang Pei Li +3 位作者 Fei Ding Zhiwen Pan Nan Liu Xiaohu You 《中国通信:英文版》 SCIE CSCD 2019年第3期154-164,共11页
Stochastic geometry is widely employed to model cellular network.But in most existing works,base stations(BSs)are modelled following a homogeneous Poisson point process(PPP)for one-tier network,or several independent ... Stochastic geometry is widely employed to model cellular network.But in most existing works,base stations(BSs)are modelled following a homogeneous Poisson point process(PPP)for one-tier network,or several independent homogeneous PPP for multi-tier network,which ignore the dependence among BSs.In this paper,a three-tier UDN(Ultra dense network)with Macrocell BSs(MBS)for basic coverage,Picocell BSs(PBSs)deployed outside the coverage area of MBSs for compensating coverage holes,and Femtocell BSs(FBSs)surrounding MBSs for capacity improvement modelled by point process with inter-tier dependence is proposed.The tier association probability,the coverage probability and area spectrum efficiency(ASE)are derived.Simulation results validate our derivation,and results show that the proposed network model has 25%-45%performance gain in ASE. 展开更多
关键词 stochastic GEOMETRY tier association PROBABILITY POISSON hole process area spectrum EFFICIENCY COVERAGE PROBABILITY
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概率密度函数的引入及概率表示 预览
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作者 叶利娟 《湖南工程学院学报:自然科学版》 2019年第4期54-57,共4页
针对概率论教学过程中学生不易理解的问题,如概率的意义、概率密度函数的意义及概率的积分表示,提出了类比法和微元法以帮助学生理解.通过类比教学法形象地描述了概率及概率密度函数的意义,并通过微元法解释了连续型随机变量事件概率的... 针对概率论教学过程中学生不易理解的问题,如概率的意义、概率密度函数的意义及概率的积分表示,提出了类比法和微元法以帮助学生理解.通过类比教学法形象地描述了概率及概率密度函数的意义,并通过微元法解释了连续型随机变量事件概率的积分表示.该教学思想和方法在民族班及普通班的教学实践中取得了较好的效果. 展开更多
关键词 概率 连续型随机变量 概率密度 分布函数 定积分 二重积分
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Pre-stack seismic waveform inversion based on adaptive genetic algorithm 预览
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作者 LIU Sixiu WANG Deli HU Bin 《世界地质:英文版》 2019年第3期188-198,共11页
Pre-stack waveform inversion, by inverting seismic information, can estimate subsurface elastic properties for reservoir characterization, thus effectively guiding exploration. In recent years, nonlinear inversion met... Pre-stack waveform inversion, by inverting seismic information, can estimate subsurface elastic properties for reservoir characterization, thus effectively guiding exploration. In recent years, nonlinear inversion methods, such as standard genetic algorithm, have been extensively adopted in seismic inversion due to its simplicity, versatility, and robustness. However, standard genetic algorithms have some shortcomings, such as slow convergence rate and easiness to fall into local optimum. In order to overcome these problems, the authors present a new adaptive genetic algorithm for seismic inversion, in which the selection adopts regional equilibrium and elite retention strategies are adopted, and adaptive operators are used in the crossover and mutation to implement local search. After applying this method to pre-stack seismic data, it is found that higher quality inversion results can be achieved within reasonable running time. 展开更多
关键词 genetic algorithm adaptive PROBABILITY REGIONAL EQUILIBRIUM SEISMIC INVERSION
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n中取k系统失效元件的数量 预览
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作者 王军玲 《洛阳理工学院学报:自然科学版》 2019年第3期87-92,共6页
本文主要研究n中取k系统失效元件数量的问题。首先,本文考虑了在t时刻并联系统正常运行时,得出失效元件为r(r=0,1,...,n-1)的概率,并且研究了一些随机序的性质,然后进一步扩展到n中取k系统中。
关键词 并联系统 n中取k系统 随机序 概率
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基于双目激光的车辆限高障碍探测技术研究 预览
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作者 丁红杰 杨洪 《汽车实用技术》 2019年第14期57-60,共4页
针对车辆在经过限高杆或拱形桥洞时,频繁发生碰撞事故,造成车顶严重受损以及道路公共设施损坏的情况,文章进行了基于双目激光的车辆限高障碍探测技术研究,通过研究确定双目激光传感器的安装方式,结合双目激光测得的距离差分信号和基于... 针对车辆在经过限高杆或拱形桥洞时,频繁发生碰撞事故,造成车顶严重受损以及道路公共设施损坏的情况,文章进行了基于双目激光的车辆限高障碍探测技术研究,通过研究确定双目激光传感器的安装方式,结合双目激光测得的距离差分信号和基于时间域的距离曲线相关程度,进行探测算法研究,判断车辆是否能够安全通过限高障碍物。并通过试验验证了系统设计的可行性。 展开更多
关键词 限高障碍 双目激光 距离信号 概率
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基于历史数据的高速多义路径概率识别方法 预览
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作者 路珊 徐刚 +1 位作者 赵卓峰 丁维龙 《计算机系统应用》 2019年第8期217-221,共5页
高速公路多义路径问题是指如何在具有多条可选路径的高速公路网中确定车辆的一条驶经路径.目前普遍采用的基于识别点的多义路径识别方法在某些情况下(如设备故障、环境亮度或透明度不够等)存在识别率低的问题,导致一些时段存在车辆多义... 高速公路多义路径问题是指如何在具有多条可选路径的高速公路网中确定车辆的一条驶经路径.目前普遍采用的基于识别点的多义路径识别方法在某些情况下(如设备故障、环境亮度或透明度不够等)存在识别率低的问题,导致一些时段存在车辆多义路径难以识别.针对以上情况,本文提出一种基于历史数据的多义路径概率识别方法,通过基于路段的聚类方法计算各路段概率值,然后结合贪心算法找出车辆的驶经路径,用来在识别设备故障时辅助识别多义路径.该方法可以有效的在识别设备故障时识别多义路径,提高了该方法的准确度. 展开更多
关键词 数据缺失 多义路径识别 概率 历史数据
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Adaptive Relaying Protocol for Decode and Forward Full-Duplex System over Rician Fading Channel:System Performance Analysis 预览
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作者 Tan N.Nguyen Minh Tran +1 位作者 Thanh-Long Nguyen Miroslav Voznak 《中国通信:英文版》 SCIE CSCD 2019年第3期92-102,共11页
In this paper,the system performance of a decode-and-forward(DF)full-duplex(FD)adaptive relaying network over the Rician fading environment is proposed,analyzed and demonstrated.In the first stage,the system is presen... In this paper,the system performance of a decode-and-forward(DF)full-duplex(FD)adaptive relaying network over the Rician fading environment is proposed,analyzed and demonstrated.In the first stage,the system is presented with the energy harvesting and information transmission processes.After that,the analytical expressions of the achievable throughput,the outage probability,and symbol error ratio(SER)were proposed,analyzed and demonstrated.Finally,the analytical results are also demonstrated by Monte-Carlo simulation in comparison with the closed-form expressions in the influence of the key system parameters.The results show that the analytical and simulated results match for all possible parameter values. 展开更多
关键词 RELAYING network THROUGHPUT OUTAGE probability SER wireless energy harvesting(EH)
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Studies on the Application of Bayesian Network in the Cause Analysis of Ship Collision 预览
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作者 Wang Yong 《船舶与海洋工程:英文版》 2019年第1期30-34,共5页
As an important means of logistics, shipping plays an important role in international trade. However, the growth of traffic density has increased the ship traffic accidents and collision takes up a greater portion. Th... As an important means of logistics, shipping plays an important role in international trade. However, the growth of traffic density has increased the ship traffic accidents and collision takes up a greater portion. This paper renders the analysis of ship collision cases in recent years and summarizes the causes. By using the basic theory of Bayesian network, the paper sets up the collision cause model. The model can be used in the cause analysis in the probability of ship collision and prediction of accident probability in practice and thus effectively reduce the ship collision accidents. 展开更多
关键词 SHIP COLLISION BAYESIAN network PROBABILITY analysis
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Sequential Approximation of Functions in Sobolev Spaces Using Random Samples 预览
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作者 Kailiang Wu Dongbin Xiu 《应用数学与计算数学学报(英文)》 2019年第3期449-466,共18页
We present an iterative algorithm for approximating an unknown function sequentially using random samples of the function values and gradients. This is an extension of the recently developed sequential approximation (... We present an iterative algorithm for approximating an unknown function sequentially using random samples of the function values and gradients. This is an extension of the recently developed sequential approximation (SA) method, which approximates a target function using samples of function values only. The current paper extends the development of the SA methods to the Sobolev space and allows the use of gradient information naturally. The algorithm is easy to implement, as it requires only vector operations and does not involve any matrices. We present tight error bound of the algorithm, and derive an optimal sampling probability measure that results in fastest error convergence. Numerical examples are provided to verify the theoretical error analysis and the effectiveness of the proposed SA algorithm. 展开更多
关键词 APPROXIMATION theory SEQUENTIAL APPROXIMATION RANDOMIZED algorithm SOBOLEV space Optimal sampling PROBABILITY measure
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基于船舶操纵模拟的船撞桥概率研究 预览
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作者 孔宪卫 张庆河 《中国安全生产科学技术》 CSCD 北大核心 2019年第10期45-50,共6页
针对船舶在桥区水域航行过程中撞击桥墩的碰撞概率问题,建立并验证了船舶操纵数学模型,模拟了船舶在不同风、水流等条件下的航行情况,改进了AASHTO船舶撞桥概率模型中几何概率的算法,提出了以模拟试验样本的航迹带中心位置坐标为均值,... 针对船舶在桥区水域航行过程中撞击桥墩的碰撞概率问题,建立并验证了船舶操纵数学模型,模拟了船舶在不同风、水流等条件下的航行情况,改进了AASHTO船舶撞桥概率模型中几何概率的算法,提出了以模拟试验样本的航迹带中心位置坐标为均值,以模拟实验样本结果计算的方差为方差的几何概率模型,同时引入停船概率模型。将改进后的模型应用于北江油金大桥船舶操纵模拟及船撞概率的研究,预测2020年北江油金大桥受上行船舶碰撞年频率大约2.81×10^-6次/a,受下行船舶碰撞年频率3.43×10^-4次/a,总碰撞频率3.461×10^-4次/a。 展开更多
关键词 通航安全 船舶操纵 数值模拟 船撞桥 概率
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基于故障树分析法的显控系统中控主机故障诊断研究 预览
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作者 侯杰 孔庆宇 +2 位作者 杜兴业 王勇 王云升 《信息通信》 2019年第5期16-17,共2页
根据中控主机的故障分析结果,对其建立故障树,并根据用户抽样调研结果计算出中间事件、底事件发生概率,最后结合故障树的逻辑关系得出底事件导致顶事件发生的概率。
关键词 中控主机 故障树 概率
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Prospective evaluation of heparin-induced thrombocytopenia expert probability and 4T scores in Chinese patients with suspected heparin-induced thrombocytopenia
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作者 Sen Li Lian-Kai Fan +1 位作者 Shu-Jie Wang Yong-Qiang Zhao 《中华医学杂志:英文版》 SCIE CAS CSCD 2019年第12期1441-1447,共7页
Background: Diagnosis of heparin-induced thrombocytopenia (HIT) is challenging. This study aimed to compare the diagnostic performance of HIT expert probability (HEP) and 4T scores, and to evaluate the inter-observer ... Background: Diagnosis of heparin-induced thrombocytopenia (HIT) is challenging. This study aimed to compare the diagnostic performance of HIT expert probability (HEP) and 4T scores, and to evaluate the inter-observer reliability for the 4T score in a clinical setting. Methods: This prospective study included HIT-suspected patients between 2016 and 2018. Three hematologists assessed the HEP and 4T scores. Correlations between scores and anti-platelet factor 4 (anti-PF4)/heparin antibodies were evaluated. Receiver operating characteristic curves and area under the curve (AUC) were used to assess the predictive accuracy of these two scoring models. The intraclass correlation coefficient (ICC) was used to assess the inter-observer agreement of 4T scores between residents and hematologists. Results: Of the 89 subjects included, 22 (24.7%) were positive for anti-PF4/heparin antibody. The correlations between antibody titer and either HEP or 4T scores were similar (r = 0.392, P < 0.01 for the HEP score;r = 0.444, P < 0.01 for the 4T score). No significant difference in the diagnostic performance was displayed between these two scores (AUC for the HEP score: 0.778 vs. AUC for the 4T score: 0.741, P = 0.357). Only 72 4T scores were collected from the residents, with a surprisingly low percentage of observers (43.1%) presenting the four individual item scores which made up their 4T score. The AUC of 4T score assessed by residents and hematologists was 0.657 (95% confidence interval [CI]: 536–0.765) and 0.780 (95% CI: 0.667–0.869, P < 0.05), respectively. The ICC of 4T score between residents and hematologists was 0.49 (95% CI: 0.29–0.65, P < 0.01), demonstrating a fair inter-observer agreement. Conclusions: The HEP score does not display a better performance for predicting HIT than the 4T score. With the unsatisfactory completion rate, the inter-observer agreement of 4T score in a tertiary hospital is fair, underscoring the necessity for continuing education for physicians. 展开更多
关键词 Heparin-induced THROMBOCYTOPENIA Clinical SCORING model 4T SCORE HIT EXPERT PROBABILITY SCORE
基于坐标的多区域风险综合模型 预览
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作者 王生玉 蔡绪涛 王正 《火力与指挥控制》 CSCD 北大核心 2019年第7期68-73,共6页
针对装备研制阶段的风险评估,采用风险可能性和风险后果的交叉结果来综合反映风险值,通过对概率-影响矩阵和典型风险综合模型进行分析研究,提出了基于坐标的多区域风险综合模型,该模型根据概率和影响在不同情况权重差别,将所有情况进行... 针对装备研制阶段的风险评估,采用风险可能性和风险后果的交叉结果来综合反映风险值,通过对概率-影响矩阵和典型风险综合模型进行分析研究,提出了基于坐标的多区域风险综合模型,该模型根据概率和影响在不同情况权重差别,将所有情况进行了区域划分。在此基础上,对区域进行连续化处理,将概率影响权扩展到所有风险情况,建立了更为详细的符合实际情况的概率-影响关系,以更加准确地对风险进行综合评估。 展开更多
关键词 多区域 风险评估 概率 影响 权重
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水下爆炸作用下的船舶倾覆概率计算 预览
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作者 丁胜 《舰船科学技术》 北大核心 2019年第6期4-6,共3页
近年来,伴随海洋资源开发力度的不断加大,加之水下爆炸技术的更新与升级,水下爆炸工程项目数量明显增多,而水下爆炸安全防护问题也随之突显出来。特别是军事领域,现代海军舰艇在水下鱼雷抗冲击性能方面提出了更高要求。在船舶海上航行... 近年来,伴随海洋资源开发力度的不断加大,加之水下爆炸技术的更新与升级,水下爆炸工程项目数量明显增多,而水下爆炸安全防护问题也随之突显出来。特别是军事领域,现代海军舰艇在水下鱼雷抗冲击性能方面提出了更高要求。在船舶海上航行的过程中,很容易受风浪影响,所以其稳定性能也十分关键,备受船舶界的关注。在这种情况下,本文基于水下爆炸作用,准确计算船舶倾覆概率,能够不断优化船舶稳定性,为其海上安全稳定航行提供有价值的参考依据。 展开更多
关键词 爆炸 倾覆 概率
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Message delay time distribution analysis for controller area network under errors
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作者 Lei-ming ZHANG Yi-chao SUN Yong LEI 《信息与电子工程前沿:英文版》 SCIE EI CSCD 2019年第6期760-772,共13页
Controller area network(CAN) is a widely used fieldbus protocol in various industrial applications.To understand the network behavior under errors for the optimal design of networked control systems, the message respo... Controller area network(CAN) is a widely used fieldbus protocol in various industrial applications.To understand the network behavior under errors for the optimal design of networked control systems, the message response time of the CAN network needs to be analyzed. In this study, a novel delay time distribution analysis method for the response messages is proposed when considering errors. In this method the complex message queues are decomposed into typical message patterns and cases. First, a stochastic fault model is developed, and the probability factor is defined to calculate the error distribution. Then the message delay time distribution for the single slave node configuration is analyzed based on the error distribution. Next, based on the delay time distribution analysis of typical patterns and cases, an analysis framework of message delay time distribution for the master/slave configuration is developed. The testbed is constructed and case studies are conducted to demonstrate the proposed methodology under different network configurations. Experimental results show that the delay time distributions calculated by the proposed method agree well with the actual observations. 展开更多
关键词 Cont ROLLER area network MESSAGE DELAY PROBABILITY dist ribution ERRORS
基于网络的定位算法研究 预览
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作者 陶峥 《通信技术》 2019年第1期91-94,共4页
近年来,室内定位技术在现代社会中扮演着越来越重要的角色。一般来说,室内定位方法包括参数化定位方法和非参数化定位方法。其中,非参数化定位方法中的位置指纹定位法被广泛研究和应用。位置指纹定位法包括离线训练和在线定位两个阶段... 近年来,室内定位技术在现代社会中扮演着越来越重要的角色。一般来说,室内定位方法包括参数化定位方法和非参数化定位方法。其中,非参数化定位方法中的位置指纹定位法被广泛研究和应用。位置指纹定位法包括离线训练和在线定位两个阶段。因此,阐述室内定位离线网络和在线网络方法,对常用的三种定位方法进行研究和拓展,并对未来的室内定位研究方向进行展望。 展开更多
关键词 IP网络 位置指纹 分类算法 概率 神经网络
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Modeling turbulent transport effects on kernel formation and ?ame propagation in an ignition process
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作者 Linghan KONG Zhuyin REN Lingyun HOU 《中国航空学报:英文版》 SCIE EI CAS CSCD 2019年第4期895-905,共11页
Reliable relighting is crucial for advanced low-emission aero-engine combustors. For forced ignition under highly-turbulent conditions, eddies of sizes being smaller than the flame kernel can affect its formation thro... Reliable relighting is crucial for advanced low-emission aero-engine combustors. For forced ignition under highly-turbulent conditions, eddies of sizes being smaller than the flame kernel can affect its formation through penetrating and modifying the kernel structure. In this study, a one-dimensional model for small-scale turbulence on kernel formation is developed through the incorporation of turbulence-induced diffusion in governing equations. With given flow conditions,the spatial and time-dependent turbulent diffusivity is modeled using the idea of residual eddy viscosity. One-dimensional spherical flames of premixed pre-vaporized n-dodecane/air mixtures under high-altitude conditions are simulated to investigate the effects of turbulence. It is revealed that the range of the equivalence ratio for successful turbulent ignition is much narrower than that for laminar ignition. The range decreases with an increased turbulent intensity, and this effect is more pronounced for a low spark energy. In addition, turbulent transport has more pronounced effects on rich mixtures. An analysis on energy budget and species profiles shows that turbulence-induced diffusion enhances the heat loss at the very beginning of the kernel formation process that could lead to ignition failure. After the flame kernel is established, turbulent transport broadens the flame front, enhances the heat release rate, and thereafter increases the flame propagation speed. 展开更多
关键词 FLAME KERNEL FLAME PROPAGATION HIGH-ALTITUDE ignition KERNEL FORMATION probability Turbulence-induced diffusion
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