Academic literature on the topic 'Extension de flamme'
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Journal articles on the topic "Extension de flamme"
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Kibrya, M. G., and G. A. Karim. "Blowout Limits of a Jet Diffusion Flame in the Presence of Small Surrounding Jet Pilot Flames." Journal of Energy Resources Technology 118, no. 2 (June 1, 1996): 140–44. http://dx.doi.org/10.1115/1.2792705.
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The blowout limit of a methane jet diffusion flame is examined in the presence of a number of much smaller pilot jet flames of different fuels arranged within an experimental burner assembly in a co-flowing stream of air. It is shown that the blowout limit of the central jet flame can be extended very appreciably by increasing the flow rate through the smaller pilot jets. The basis for this extension to the blowout limit and the role of some changes in the operating parameters are discussed. It is suggested that the extension to the blowout limit observed is due mainly to the thermal contribution of the pilot jet flames.
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Yedinak, Kara M., Jack D. Cohen, Jason M. Forthofer, and Mark A. Finney. "An examination of flame shape related to convection heat transfer in deep-fuel beds." International Journal of Wildland Fire 19, no. 2 (2010): 171. http://dx.doi.org/10.1071/wf07143.
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Fire spread through a fuel bed produces an observable curved combustion interface. This shape has been schematically represented largely without consideration for fire spread processes. The shape and dynamics of the flame profile within the fuel bed likely reflect the mechanisms of heat transfer necessary for the pre-heating and ignition of the fuel during fire spread. We developed a simple laminar flame model for examining convection heat transfer as a potentially significant fire spread process. The flame model produced a flame profile qualitatively comparable to experimental flames and similar to the combustion interface of spreading fires. The model comparison to flame experiments revealed that at increasing fuel depths (>0.7 m), lateral flame extension was increased through transition and turbulent flame behaviour. Given previous research indicating that radiation is not sufficient for fire spread, this research suggests that flame turbulence can produce the convection heat transfer (i.e. flame contact) necessary for fire spread particularly in vertically arranged, discontinuous fuels such as shrub and tree canopies.
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F. Ganji, Hamed, Viktor Kornilov, Philip de Goey, Ines Lopez Arteaga, and Jeroen van Oijen. "Characterization and Identification of Thermoacoustic behaviour of flames anchored on burner decks with multiple perforation; Transfer Function (de)composition approach." INTER-NOISE and NOISE-CON Congress and Conference Proceedings 265, no. 4 (February 1, 2023): 3609–20. http://dx.doi.org/10.3397/in_2022_0508.
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The appearance of thermoacoustic instability in combustion systems depends on thermoacoustic property (e.g., Transfer Function (TF)) of used burner/flame. Therefore, an attractive approach to cope with the instability is the purposeful design of the burner thermo-acoustics. One of the ideas of how the flame TF can be altered/designed is based on the heuristic idea that the acoustic response of one flame can be counteracted by the appropriately phased response of another flame. For the particular case of premixed, burner deck anchored conical flames, the TF depends on the diameter of perforation. It suggests the concept of combining different size and shape of perforations in one burner deck. In the present work, the acoustic response of sintered ceramic fibre burners with mixed perforation is investigated using the TF (de)-composition principle. By this approach, the cumulative flame TF can be represented as a weighted sum of elemental TF's of the groups of flames on the basis of the additive nature of the individual flame heat release rate. The capability of this principal to offer a designing framework for optimization of burner deck patterns aiming desirable acoustic characteristics will be tested by a course of measurements. Possible simplifications and extensions of the TF (de)composition principle will be discussed.
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Blunsdon, C. A., Z. Beeri, W. M. G. Malalasekera, and J. C. Dent. "Comprehensive Modeling of Turbulent Flames With the Coherent Flame-Sheet Model—Part I: Buoyant Diffusion Flames." Journal of Energy Resources Technology 118, no. 1 (March 1, 1996): 65–71. http://dx.doi.org/10.1115/1.2792695.
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A modified version of the computational fluid dynamics code KIVA-II was used to model the transient behavior of buoyant turbulent diffusion flames burning in still air. Besides extensions to the range of permitted boundary conditions and the addition of buoyancy terms to the turbulence model, KIVA-II was augmented by a version of the coherent flame-sheet model, Tesner’s soot generation model, Magnussen’s soot oxidation model, and an implementation of the discrete transfer radiation model that included both banded and continuum radiation. The model captured many of the features of buoyant turbulent flames. Its predictions supported experimental observations regarding the presence and frequency of large-scale pulsations, and regarding axial distributions of temperature, velocity, and chemical species concentrations. The radial structure of the flame was less well represented. The axial radiative heat flux distribution from the flame highlighted deficiencies in the soot generation model, suggesting that a model of soot particle growth was required.
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Obando Vega, Pedro Javier, Axel Coussement, Amsini Sadiki, and Alessandro Parente. "Non-Premixed Filtered Tabulated Chemistry: Filtered Flame Modeling of Diffusion Flames." Fuels 2, no. 2 (March 25, 2021): 87–107. http://dx.doi.org/10.3390/fuels2020006.
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The flame front filtering is a well-known strategy in turbulent premixed combustion. An extension of this approach for the non-premixed combustion context has been proposed by means of directly filtering counterflow diffusion flamelets. Promising results were obtained for the non-premixed filtered tabulated chemistry formalism on 1-D and 2-D unresolved counterflow flame configurations. The present paper demonstrates the soundness of this approach on a 3-D real laminar non-premixed coflow flame. The model results are compared against the direct filtering of the fully resolved laminar diffusion flame showing that the formalism adequately describes the underlying physics. The study reveals the importance of the one-dimensional counterflow flamelet hypothesis, so that the model activation under this condition is ensured by means of a flame sensor. The consistent coupling between the model and the flame sensor adequately retrieves the flame lift-off and satisfactorily predicts the profile extension due to the filtering process.
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Albayrak, Alp, and Wolfgang Polifke. "An analytical model based on the G-equation for the response of technically premixed flames to perturbations of equivalence ratio." International Journal of Spray and Combustion Dynamics 10, no. 2 (November 22, 2017): 103–10. http://dx.doi.org/10.1177/1756827717740776.
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A model for the response of technically premixed flames to equivalence ratio perturbations is proposed. The formulation, which is an extension of an analytical flame tracking model based on the linearized G-equation, considers the flame impulse response to a local, impulsive, infinitesimal perturbation that is transported by convection from the flame base towards the flame surface. It is shown that the contributions of laminar flame speed and heat of reaction to the impulse response exhibit a local behavior, i.e. the flame responds at the moment when and at the location where the equivalence ratio perturbation reaches the flame surface. The time lag of this process is related to a convective time scale, which corresponds to the convective transport of fuel from the base of the flame to the flame surface. On the contrary, the flame surface area contribution exhibits a non-local behavior: albeit fluctuations of the flame shape are generated locally due to a distortion of the kinematic balance between flame speed and the flow velocity, the resulting wrinkles in flame shape are then transported by convection towards the flame tip with the restorative time scale. The impact of radial non-uniformity in equivalence ratio perturbations on the flame impulse response is demonstrated by comparing the impulse responses for uniform and parabolic radial profiles. Considerable deviation in the phase of the flame transfer function, which is important for thermo-acoustic stability, is observed.
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Tornatore, Cinzia, and Magnus Sjöberg. "Optical Investigation of a Partial Fuel Stratification Strategy to Stabilize Overall Lean Operation of a DISI Engine Fueled with Gasoline and E30." Energies 14, no. 2 (January 12, 2021): 396. http://dx.doi.org/10.3390/en14020396.
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This paper offers new insights into a partial fuel stratification (PFS) combustion strategy that has proven to be effective at stabilizing overall lean combustion in direct injection spark ignition engines. To this aim, high spatial and temporal resolution optical diagnostics were applied in an optically accessible engine working in PFS mode for two fuels and two different durations of pilot injection at the time of spark: 210 µs and 330 µs for E30 (gasoline blended with ethanol by 30% volume fraction) and gasoline, respectively. In both conditions, early injections during the intake stroke were used to generate a well-mixed lean background. The results were compared to rich, stoichiometric and lean well-mixed combustion with different spark timings. In the PFS combustion process, it was possible to detect a non-spherical and highly wrinkled blue flame, coupled with yellow diffusive flames due to the combustion of rich zones near the spark plug. The initial flame spread for both PFS cases was faster compared to any of the well-mixed cases (lean, stoichiometric and rich), suggesting that the flame propagation for PFS is enhanced by both enrichment and enhanced local turbulence caused by the pilot injection. Different spray evolutions for the two pilot injection durations were found to strongly influence the flame kernel inception and propagation. PFS with pilot durations of 210 µs and 330 µs showed some differences in terms of shapes of the flame front and in terms of extension of diffusive flames. Yet, both cases were highly repeatable.
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Haubold, Thorben Sören, Laura Puchot, Antoine Adjaoud, Pierre Verge, and Katharina Koschek. "Bio-Based Bisbenzoxazines with Flame Retardant Linker." Polymers 13, no. 24 (December 10, 2021): 4330. http://dx.doi.org/10.3390/polym13244330.
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This work explores the strategy of incorporating a highly substituted reactive flame retardant into a benzoxazine moiety. For this purpose, a DOPO-based flame retardant received a chain extension via reaction with ethylene carbonate. It was then reacted with phloretic acid to obtain a diphenol end-capped molecule, and further reacted with furfurylamine and paraformaldehyde to obtain a benzoxazine monomer via a Mannich-like ring closure reaction. This four-step synthesis yielded a partly bio-based halogen-free flame retardant benzoxazine monomer (DOPO-PA-fa). The successful synthesis was proven via NMR, IR and MS analysis. The polymerization behavior was monitored by DSC and rheological analysis both showing the polymerization starts at 200 °C to yield pDOPO-PA-fa. pDOPO-PA-fa has a significant thermal stability with a residual mass of 30% at 800 °C under ambient atmosphere. Furthermore, it reached a V-0 rating against small flames and an OI of 35%. Blended with other benzoxazines, it significantly improves their thermal stability and fire resistance. It emphasizes its potential as flame retardant agent.
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Li, Linjie, Wuchao Zhang, Zihe Gao, and Liangwen Wei. "Experimental study on the flame merging and ceiling impingement behavior of transversely located double fire sources in an urban utility tunnel." Indoor and Built Environment 32, no. 1 (January 2023): 286–95. http://dx.doi.org/10.1177/1420326x221147427.
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The investigation of the fire characteristics and propagation behaviour in the urban utility tunnel is of great practical importance, especially for the conditions with double fire sources. In this work, a 1/8th scaled urban utility tunnel model was built to conduct the experiments to characterize the flame merging and ceiling impingement behaviour of transversely located double fire sources. Two rectangular fire sources with the same dimension were used, and their heat release rate (HRR) and fire source spacings were varied to consider the typical scenarios. Results show that for the smaller HRR, the tunnel ceiling and sidewalls have little influence on the flame merging of double fire sources. With the increase of HRR, the flame gradually impinges on the tunnel ceiling and forms a stable ceiling jet flame extension, and the ceiling and sidewalls of the tunnel can promote the merging of the flames of the double fire sources. Besides, with the increase of the fire source spacings, the flame merging probability P m can be divided into three stages, that is, (i) complete merging stage, (ii) intermittent merging stage and (iii) complete separation stage. On this basis, the predicting relation of P m was obtained by using the piecewise function.
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Palacios, A., W. García, and B. Rengel. "Flame shapes and thermal fluxes for an extensive range of horizontal jet flames." Fuel 279 (November 2020): 118328. http://dx.doi.org/10.1016/j.fuel.2020.118328.
Full textDissertations / Theses on the topic "Extension de flamme"
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Wang, Aijuan. "Experimental and numerical investigation of the confinement effect on the impinging flame in a compartment." Electronic Thesis or Diss., Bourges, INSA Centre Val de Loire, 2021. http://www.theses.fr/2021ISAB0002.
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Le phénomène de flamme de diffusion impactant une paroi est fréquent dans les scénarios d’incendie en milieu clos. Celui-ci peut entraîner à avoir des conséquences désastreuses en termes de vie humaine et de biens matériels. En effet, lorsqu'une flamme incidente se produit dans un compartiment, elle peut augmenter le risque de propagation du feu de celui-ci vers une autre pièce à travers une explosion de fumée représentant une menace pour les personnes pié-gées. Afin d’apporter des éléments de compréhension sur le comportement de ce type de flamme, de nombreuses études ont réalisé. Celles-ci se sont intéressées sur des flammes impac-tant un plafond en milieu ouvert ou semi-confiné. Cependant il y a peu, voire aucuns travaux qui se sont penchés sur l’étude du comportement d’une flamme incidente dans un compartiment confiné sous ventilé. Dans l’objectif d’apporter des éléments de compréhension en lien avec l’effet du confinement sur la dynamique d’une flamme impactant un plafond, une étude expé-rimentale et numérique est réalisée dans le cadre de cette thèse.L’ensemble des données a été obtenu à l’aide d’un dispositif expérimental représentant un appartement d’étudiant à échelle réduite.Le banc d'essai est un compartiment représentant une maquette d’appartement à petite échelle (1 :10). La conception et dimensionnement a été réalisée sur la base des lois de simili-tudes. Les niveaux de confinement ont été définis en fonction des ouvertures de l’enceinte et du débit calorifique potentielle. A partir de ces deux paramètres, le niveau de confinement peut être associé à la richesse de l’enceinte. Pour cela, huit débits caloriques différents ainsi que cinq possibilités d’ouvertures ont été proposés. À partir des expériences réalisées avec les huit débits calorifiques et les cinq configurations d’ouvertures, l'effet de confinement sur la dynamique d’une flamme impactant un plafond a été effectué en se basant sur les paramètres physico-chimiques, tels que l'extension de la flamme, l'oscillation de la flamme, la distribution de la température et l'analyse des gaz.De plus, grâce à la modélisation numérique de la flamme impactant le plafond à l’aide du code CFD : Fire Dynamics Simulator (FDS), il a été possible d’apporter des éléments supplé-mentaires dans l’analyse des écoulements réactifs associée à l’interaction flamme paroi en fonc-tion du niveau de confinement. Le choix des modèles numériques a été effectué à partir d’une étude préliminaire visant à justifier la fiabilité et la précision du modèle numérique à reproduire les données expérimentales ainsi que des évolutions obtenues à partir de corrélations empiriques obtenues dans les littératures.A partir des analyses réalisées dans cette étude, il est possible de fournir des éléments de décisions lors de la conception et la mise en place de détecteurs d'incendie au plafond dans un compartiment et également d’aider à une meilleure estimation de la probabilité de propagation du feu lors d'un incendie de compartiment par le biais d’une explosion de fumée riche en gaz imbrûlésThe phenomenon of diffusion impinging flame is common in industrials, leading to disas-trous consequences in terms of life and property. When impinging flame occurs in a compart-ment, it may enhance the risk of fire propagation and pose a greater threat to trapped people. Lots of studies dealt with flame impinging an unconfined or confined ceiling while little work focused on the impinging flame in a confined compartment. With the objective of providing understanding related to the confinement effect on the impinging flame in a compartment, both experimental and numerical studies carried out to build up the framework of this thesis. A compartment model representing a reduced scale (1:10) student compartment was uti-lized based on the scaling law such that a test bench with suitable instrumentations for carrying out measurements was developed. Configurations of five confinement levels were constructed by the condition of windows and door in the compartment and heat release rate (HRR) was var-ied between 0.5 kW and 18.6 kW. Through series of experiments, the confinement effect on the dynamics of flame impinging a ceiling was addressed with physicochemical parameters, such as flame extension, flame oscillation, temperature distribution and gas analysis. In addition, on account of the numerical modeling of flame impinging a ceiling using the CFD code: Fire Dynamics Simulator (FDS), it was possible to provide additional elements in the analysis of reactive flows associated with the flame-wall interaction as a function of the confinement level. The choice of numerical models was made on the basis of a preliminary study aimed at justifying the reliability and precision of the numerical modelling in reproducing the experimental data as well as the empirical correlations obtained in the literatures. From the analyzes in this study, it is possible to provide guidance for fire safety engineering in the field of fire risk assessment and fire protection design of buildings
Books on the topic "Extension de flamme"
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Lyndon B. Johnson Space Center., ed. Effects of gas-phase radiation and detailed kinetics on the burning and extension of a solid fuel. Houston, Tex: National Aeronautics and Space Administration, Johnson Space Center, 2001.
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Rhatigan, Jennifer L. Effects of gas-phase radiation and detailed kinetics on the burning and extension of a solid fuel. Houston, Tex: National Aeronautics and Space Administration, Johnson Space Center, 2001.
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Lyndon B. Johnson Space Center., ed. Effects of gas-phase radiation and detailed kinetics on the burning and extension of a solid fuel. Houston, Tex: National Aeronautics and Space Administration, Johnson Space Center, 2001.
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Effects of gas-phase radiation and detailed kinetics on the burning and extension of a solid fuel. Houston, Tex: National Aeronautics and Space Administration, Johnson Space Center, 2001.
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Zhukovsky, Donna S. Treatment of Opioid-Induced Constipation in Advanced Illness (DRAFT). Edited by Nathan A. Gray and Thomas W. LeBlanc. Oxford University Press, 2018. http://dx.doi.org/10.1093/med/9780190658618.003.0025.
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Opioid-induced constipation is a major problem for patients with advanced medical illness despite aggressive use of bowel regimens. Methylnaltrexone is an opioid antagonist with limited ability to cross the blood–brain barrier and thus is thought to induce opioid withdrawal at the level of the gastrointestinal tract without causing central withdrawal and flare of pain. This chapter describes and evaluates a randomized controlled trial of methylnaltrexone versus placebo and an open label extension study for patients with advanced illness and opioid-induced constipation. Primary outcomes are efficacy and safety. The chapter concludes with a discussion of the possible role of methylnaltrexone in the therapeutic armamentarium of opioid induced constipation.
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Evans, Richard Kent. MOVE. Oxford University Press, 2020. http://dx.doi.org/10.1093/oso/9780190058777.001.0001.
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This book is a religious history of MOVE, a small, mostly African American religious group devoted to the religious teachings of John Africa that emerged in Philadelphia in the early 1970s. MOVE is perhaps best known for the MOVE Bombing. In 1985, the Philadelphia Police Department—working in concert with federal and state law enforcement—attacked a home that MOVE people shared in West Philadelphia, involving hundreds of police officers and firefighters and using tear gas, 10,000 rounds of ammunition, and improvised explosives. Most infamously, a police officer dropped a bomb containing C-4 explosives, which he had acquired from the FBI, from a helicopter onto the roof of the MOVE house. The bomb started a fire, which officials allowed to spread in hopes of burning MOVE people out of the house. Police officers fired upon MOVE people who tried to escape the flames. Eleven MOVE people died in the attack, including John Africa. Five of those who died were children. Based on never-before-seen law enforcement records and extensive archival and ethnographic research, MOVE: An American Religion reinterprets the history of MOVE from its origins in the late 1960s, its growth in the early 1970s, its conflicts with the United States government from the mid-1970s to the mid-1980s, and its presence today. It is the first full-length academic study of MOVE since 1994 and is the first book to consider MOVE as a religion.
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Pilkington, Clarissa, and Liza McCann. Paediatric polymyositis and dermatomyositis. Oxford University Press, 2013. http://dx.doi.org/10.1093/med/9780199642489.003.0125.
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Juvenile polymyositis and dermatomyositis are inflammatory myopathies that affect muscle. Dermatomyositis also affects skin, and can have many extramuscular manifestations. Inflammatory myopathies are uncommon in childhood, with dermatomyositis occurring more than polymyositis. For this reason, published research has concentrated on juvenile dermatomyositis. The spectrum of disease severity ranges from mild cases that can recover completely without treatment, to multisystem inflammation that can be fatal. Treatments have improved over the decades, reducing mortality from 30% before the era of steroids, to less than 1% in the present day. Juvenile cases of dermatomyositis differ from those seen in adulthood, without tendency for associated malignancy, and a far greater incidence of calcinosis. Calcinosis can be deposited as small calcinotic lumps or as sheets of calcinosis. It is very difficult to treat and causes extensive morbidity, and depending on where the calcinosis is deposited, it can cause severe disability or even death. Over the last decade, international collaborative work has concentrated on developing disease activity and assessment tools for both adult and juvenile forms of myositis. This will enable more subjective study of these rare diseases in multinational cohort studies, and enable clinical trials to investigate drug treatments. This work led to the first international double-blind placebo controlled trial of treatment in both adults and children with dermatomyositis (using rituximab as the drug). Further international collaboration has led to the development of core outcome variables, a definition of disease flare, and ongoing work on classification criteria.
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Pilkington, Clarissa, and Liza McCann. Paediatric polymyositis and dermatomyositis. Oxford University Press, 2016. http://dx.doi.org/10.1093/med/9780199642489.003.0125_update_002.
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Juvenile polymyositis and dermatomyositis are inflammatory myopathies that affect muscle. Dermatomyositis also affects skin, and can have many extramuscular manifestations. Inflammatory myopathies are uncommon in childhood, with dermatomyositis occurring more than polymyositis. For this reason, published research has concentrated on juvenile dermatomyositis. The spectrum of disease severity ranges from mild cases that can recover completely without treatment, to multisystem inflammation that can be fatal. Treatments have improved over the decades, reducing mortality from 30% before the era of steroids, to less than 1% in the present day. Juvenile cases of dermatomyositis differ from those seen in adulthood, without tendency for associated malignancy, and a far greater incidence of calcinosis. Calcinosis can be deposited as small calcinotic lumps or as sheets of calcinosis. It is very difficult to treat and causes extensive morbidity, and depending on where the calcinosis is deposited, it can cause severe disability or even death. Over the last decade, international collaborative work has concentrated on developing disease activity and assessment tools for both adult and juvenile forms of myositis. This will enable more subjective study of these rare diseases in multinational cohort studies, and enable clinical trials to investigate drug treatments. This work led to the first international double-blind placebo controlled trial of treatment in both adults and children with dermatomyositis (using rituximab as the drug). Further international collaboration has led to the development of core outcome variables, a definition of disease flare, and ongoing work on classification criteria.
Book chapters on the topic "Extension de flamme"
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Fernandes, E. C., and M. V. Heitor. "On the Extension of a Laser-Doppler Velocimeter to the Analysis of Oscillating Flames." In Laser Techniques Applied to Fluid Mechanics, 383–401. Berlin, Heidelberg: Springer Berlin Heidelberg, 2000. http://dx.doi.org/10.1007/978-3-642-56963-0_25.
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Diwakar, Philip, Yuqing Liu, and Ismat ElJaouhari. "Evaluation of Flange Leakage due to Thermal Bowing and Shock." In Ageing and Life Extension of Offshore Facilities, 267–74. ASME, 2022. http://dx.doi.org/10.1115/1.885789_ch21.
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During a flaring event, some operating conditions in an LNG plant cause liquid refrigerant to be introduced into a flare header causing large temperature gradients between the bottom and top wall and lead to vertical and lateral displacements along with rotation of the horizontal header. This thermal bowing is a serious problem with risk of flange leakage due to differential thermal expansion between bolts and flange and pipe cracks at high stress concentration location as it lifts off the supports. This paper evaluates the introduction of warm gas into the flare header to prevent a flange leakage as a mitigation attempt. This paper recounts the use of Fluid Structure Interaction (FSI) to study bowing and flange leakage mitigation. The liquid flowing from the lateral into the main header pipe is multiphase in the dispersed, stratified, slug or annular flow régime. Multiphase flows with heat transfer are analyzed using Computational Fluid Dynamics (CFD) and conjugate heat transfer for steel. The temperatures on the metal are then transferred to a Finite Element Analysis (FEA) and analyzed for thermal stresses and deformation due to bowing. Elastic plastic Service Criteria Assessment per ASME BPVC Sec-VIII, Div.2 Part 5.2.4.3 (b) is performed to calculate Von-Mises, peak stresses and derive membrane and bending stresses on the hub, bolts, and gasket. These stresses are compared to ASME standard allowable limits. Based on these results, risk of flange leakage is evaluated, and mitigations are recommended to reduce the risk.
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"THE FLAME IONIZATION DETECTOR AND ITS EXTENSIONS." In Chromatographic Detectors, 117–36. CRC Press, 1996. http://dx.doi.org/10.1201/9781482273564-13.
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Salama, Mamdouh M. "Ageing and Life Extention of Pipelines." In Ageing and Life Extension of Offshore Facilities, 231–32. ASME, 2022. http://dx.doi.org/10.1115/1.885789_pt4.i1.
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This section addresses issues associated with degradation, life extension and reuse of pipelines. In addition, one paper in the section addresses an issue related to leak potential of an LNG flare header due to temperature gradient and another paper addresses integrity assessment of pressure vessels. Regarding pipelines, there three main aspects that affect their ageing assessment and life extension studies. These are: 1) time dependent materials degradation such as corrosion and fatigue, 2) changes in operational conditions particularly fluid composition, and 3) accidental damage such as drop object impact. Maintaining safe operating condition of pipelines, particularly those handling corrosive fluids requires implementation of proper corrosion control strategy that includes inspection and maintenance programs to avoid uneconomical decisions if inspection and maintenance are scheduled too early, and to ensure against increasing the probability of failure leading to unacceptable risk if the inspection and maintenance is scheduled too late. The papers in this section highlight the importance of in-line inspection as well as requalification in case of change of operating conditions.
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Simon, Gregory L. "Introduction." In Flame and Fortune in the American West. University of California Press, 2016. http://dx.doi.org/10.1525/california/9780520292802.003.0001.
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This introductory chapter presents the author's recollections about the fire that almost burned down his childhood home when he was sixteen. He was home alone when he heard a policeman outside the house asking residents to evacuate. He describes seeing his neighbors' homes became the source of smoke and embers dropping in their backyards. He returns to his house to pick up his cat, gets in the car, and leaves. Returning home with his parents the next day, they find that their home remained fully intact alongside a neighbor to each side. While he was overjoyed to see the structure and all their possessions in one piece, this euphoria was quickly lost to the sight of smoldering ruins all around, including their neighbors' and friends' homes. In retrospect, he concludes that given the day's conditions and the previous century of extensive residential development, the outcome of the 1991 Tunnel Fire was both unsurprising and inevitable.
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Emblidge, David. "North Carolina." In The Appalachian Trail Reader, 117–55. Oxford University PressNew York, NY, 1996. http://dx.doi.org/10.1093/oso/9780195100914.003.0008.
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Abstract The undulating Nantahala Mts., from Wayah Bald, North Carolina. Trail miles: 95.6 in North Carolina, 207.7 shared with Tennessee Trail maintenance: Nantahala Hikmg Club, National Park Service and Smoky Mts. Hikmg Club (in Great Smoky Mts. National Park), Carolina Mt. Club Highest point: Clingmans Dome, 6,643 ft. (highest point on the AT) Broadest rivers: French Broad, Nantahala (bridge at Wesser over kayak racecourse), Little Tennessee (AT crosses 480-ft.-high Fontana Dam) Features: The AT traverses most-visited national park in the U.S. (Great Smoky Mts.), with extraordinary variety of plant life (balsam fir, flame azalea) due to sustained high elevation and abundant precipitation. Extensive wilderness areas in national park and forests; over 70 miles of crest-line trail; spectacular vistas.
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Getachew, Tsegaye, and Mesay Dejene. "Low Temperature Combustion in Diesel Engines." In Diesel Engines - Current Challenges and Future Perspectives [Working Title]. IntechOpen, 2023. http://dx.doi.org/10.5772/intechopen.1002041.
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The growing energy demand for transportation has led to a shift towards eco-friendly combustion or improved diesel engines with increased efficiency, reduced emissions, and sustainability. Low-temperature combustion (LTC) aims to achieve controlled combustion, balancing optimal performance with lower NOx and SO2 emissions. This chapter summarizes the recent trends in LTC strategies under further exploration such as fuel injection techniques, optimized air-fuel mixing, and accurate combustion phasing management, to discern existing literatures in extensive efforts to reduce flame stability and emissions. Subsequently, LTC faces challenges like stable ignition, precise control, and economical fuel choice. Liquefied biogas, methanol, bio-fuels, and thermo-physically enhanced biofuels are among the LTC diesel alternative fuels under investigation. Higher-octane fuels like biodiesels exhibited promising performance at low to medium loads, while natural gases and dual-fuel mode techniques seen promising choices for high-duty applications. Studies revealed that stakeholder collaboration could make cleaner fuel choices, meeting rigorous emissions rules while operating optimal LTC engines. Therefore, Future LTC research should focus on emission reduction, fuel flexibility, optimum performance at various working conditions, combustion stability, and accurate modeling and simulation.
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Almeida, Miguel, MohammadReza Modarres, Juan Antonio Muñoz, and Luís Mário Ribeiro. "Flammability characteristics of typical garden species." In Advances in Forest Fire Research 2022, 602–9. Imprensa da Universidade de Coimbra, 2022. http://dx.doi.org/10.14195/978-989-26-2298-9_92.
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The large fires of the recent years have caused tragic episodes that have led to the death of many hundreds of people and the loss of buildings of great social and economic value. Several of these impacts could have been avoided if the fuel management around buildings had been appropriate. Many studies on flammability are dedicated to wild fuels present in forest, shrublands or grasslands. However, the existing data on the vegetation typical of the surroundings closest to the constructions (e.g., gardens) is scarce. Besides being the fuels closest to the buildings, these are fuels that normally can be effectively managed by the building owners, i.e., their management is within the reach of the common citizens. The aim of this work was to characterize the flammability parameters for several typical garden species in the Mediterranean Basin. An extensive experimental program was carried out to characterize individual plants of the following species: XXX. The parameters analyzed and that are presented are: flame dimensions, heat flux, fire intensity, XXX. This study has two main objectives: 1) provide data that allows fire behavior modelling in the proximity of dwelling houses; and 2) the determination of the safety distance which the species analyzed must keep from buildings in order to prevent their ignition. Some of the tests performed showed that the presence of some species in the proximity of buildings (not attached) can be beneficial due to their low inflammability and because they can constitute an obstacle to the passage of firebrands, which can ignite the construction.
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Varatharajan, Nirubana, Deepika Chandra Sekaran, Karthikeyan Murugan, and Vanniarajan Chockalingam. "Rice Aroma: Biochemical, Genetics and Molecular Aspects and Its Extraction and Quantification Methods." In Rice [Working Title]. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.98913.
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Aroma in rice is unique and a superior grain quality trait, varieties especially Basmati and Jasmine-type are fetching a high export price in the International markets. Among the identified volatile aroma compounds, 2AP (2 acetyl-1-pyrroline) is believed to be the distinctive biochemical compound contributing the flavor in rice. Genetically, aroma in rice arises by the phenotypic expression of spontaneous recessive mutations of the OsBadh2 gene (also known as fgr/badh2 /osbadh2/os2AP gene) which was mapped on chromosome 8. An 8-bp deletion in the exon 7 of this gene was reported to result in truncation of betaine aldehyde dehydrogenease enzyme whose loss-of-function lead to the accumulation of a major aromatic compound (2AP) in fragrant rice. Among the different sampling methods and analytical techniques for the extraction and quantification of scentedness, simultaneous distillation extraction (SDE) is traditional and normalized, whereas solid-phase micro extraction (SPME) and supercritical fluid extraction (SFE) are new, very simple, rapid, efficient and most importantly solvent-free methods. These methods are coupled with Gas Chromatography–Mass Spectrometry (GC–MS), Gas Chromatography-Flame Ionization Detector (GC-FID) and/or Gas chromatography olfactometry (GC-O) and also with sensory evaluation for readily examining 2AP compound found in rice. The major factor affecting the aroma in rice was their genetic makeup. However, the aroma quality may be differed due to different planting, pre-harvest and postharvest handling and storage. For a more extensive elucidation of all effective and fundamental factors contributing to fragrance, it is essential to explore target quantitative trait loci (QTLs) and their inheritance and locations.
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Deva, Dr Varsha, and Ms Shelly Raghav. "A COMPREHENSIVE REVIEW OF MICROSCOPICAL CHARACTERS OF BUTEA MONOSPERMIA FLOWER." In MICROSCOPICAL EVALUATION OF MEDICINAL PLANTS. KAAV PUBLICATIONS, 2023. http://dx.doi.org/10.52458/9788196830014.2023.eb.ch-01.
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The Butea monosperma, commonly referred to as the Flame of the Forest or Palash, has long been a subject of fascination and intensive investigation within the realm of botanical sciences. This remarkable flowering tree, adorned with its striking crimson blossoms, has not only enraptured the hearts of nature enthusiasts but has also sparked the inquisitiveness of researchers and scholars on a global scale. Beyond its visual splendor, the microscopic character of the Butea monosperma flower has been the focus of substantial research, with numerous research papers and articles dedicated to uncovering its intricacies. Delving into the concealed microcosm within the Butea monosperma flower reveals a world of botanical wonders. Researchers have undertaken comprehensive investigations into the microscopic attributes of this flower, ranging from its intricate cellular composition to the mechanisms governing its reproductive processes. This exploration has unearthed a multitude of captivating findings, shedding light on its pivotal role in pollination dynamics, seed development, and ecological interactions. This chapter offers a succinct synthesis of the extensive research conducted on the microscopical character of the Butea monosperma flower. It presents an overview of the structural complexities that characterize the flower, including its cellular makeup and unique adaptations, and elucidates their significance in the context of reproduction and ecological relationships. Furthermore, it underscores the broader implications of this research, not only for the understanding of Butea monosperma but also for the advancement of botanical science and the imperative conservation efforts aimed at preserving this species. Through this exploration, we aim to provide a comprehensive snapshot of the concealed world residing within the fiery blossoms of Butea monosperma, emphasizing the invaluable contributions of the research community in unraveling the microscopic mysteries that surround this captivating botanical specimen.
Conference papers on the topic "Extension de flamme"
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Boyde, Jan M., Massimiliano Di Domenico, Berthold Noll, and Manfred Aigner. "Spark Ignition Simulations and the Generation of Ignition Maps by Means of a Turbulent Flame Speed Closure Approach." In ASME Turbo Expo 2010: Power for Land, Sea, and Air. ASMEDC, 2010. http://dx.doi.org/10.1115/gt2010-22211.
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This paper presents a numerical investigation of ignition phenomena in turbulent partially premixed methane/air flames. In this work, a turbulent flame speed closure model (TFC) is employed with an ignition delay module extension. The model is applied to two partially premixed test cases under standard conditions in the configuration of a shearless flame and a counter flow flame, respectively. For both setups, the flame kernel propagation and consequent establishment or extinction of the flame are examined. A shearless configuration represents the first test case under investigation. The study demonstrates the large influence of the mean flow parameters on achieving a successful ignition of the domain. The second test case under examination is a counterflow geometry. A sensitivity analysis with respect to spark ignition position and ignition energy is performed. The simulations show that flame kernel spreading is largely influenced by the magnitude of turbulence occurring in the flow, leading to an enhanced propagation in areas with a moderate turbulence degree, whereas high turbulence can be detrimental for the flame establishment due to extensive heat losses. Another observation is that a successful ignition of the domain can occur, even in cases in which the ignition energy is not placed in an area with flammable mixture. The comparison with experimental data shows a good agreement, both in terms of successful ignition and flame kernel propagation.
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Saurabh, Aditya, and C. O. Paschereit. "Combustion Instability in a Swirl Flow Combustor With Transverse Extensions." In ASME Turbo Expo 2013: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/gt2013-95732.
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The present investigation is an analysis of self-excited combustion instability in a swirl flame-based combustor with transverse extensions. Transverse extensions create the possibility of studying flame interaction with transverse acoustic oscillations. Such investigation important for understanding the phenomenon of thermoacoustic instability in annular combustors, where during thermoacoustic instability, azimuthal acoustic modes of the combustor couple with the multiple flames of the combustor. Flame and flow field dynamics during self-excited thermoacoustic instability in the single burner test-rig is presented here. These results are then compared to the dynamics of the isothermal and reacting flows in response to axial and transverse acoustic forcing. Both axial and transverse forcing led to the formation of axisymmetric shear layer vortices. Adding to the insight gained from previous investigations, these results suggest that that swirl flow dynamics in response to transverse acoustics consists of a non-trivial, direct effect of transverse acoustics on the flow field, in addition to its response to longitudinal fluctuations induced by transverse forcing.
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Torii, Shuichi, Sze Man Simon Chan, and Toshiaki Yano. "Flame Blowoff Limit Phenomenon of Turbulent Jet Diffusion Flames With Annular Counterflow." In ASME 2002 International Mechanical Engineering Congress and Exposition. ASMEDC, 2002. http://dx.doi.org/10.1115/imece2002-39059.
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The present study deals with the transport phenomena of turbulent jet diffusion flames with air-suction flow and the possibility of extending the flame blow-off limits through the shear stress augmentation using the annular counterflow technique. The experimental apparatus employed here comprises a fuel nozzle placed at the center of a concentric annulus with an outer cylinder adopted to encompass the nozzle. Fuel jet is allowed to eject upwards and turbulent jet diffusion flames are formed by igniting the jet and by increasing the volume flow rates of fuel. It is found that (1) the augmentation of turbulent shear effect exerted on the shear layer formed between the jet flames and the opposed flow of air causes an extension of flame blowoff limits, (2) by using the annular counterflow technique, the flame lift-off height is suppressed than the normal diffusion flame, and (3) its height is correlated using the effective air-suction momentum flux proposed here.
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Subash, Arman Ahamed, Robert Collin, Marcus Aldén, Atanu Kundu, and Jens Klingmann. "Investigation of Hydrogen Enriched Methane Flame in a Dry Low Emission Industrial Prototype Burner at Atmospheric Pressure Conditions." In ASME Turbo Expo 2017: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/gt2017-63924.
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Experiments were performed on a prototype 4th generation DLE (dry low emission) burner under atmospheric pressure conditions to investigate the effects of hydrogen (H2) enrichment on methane (CH4) flames. The burner assembly was designed to have three concentrically arranged premixed sections: an outer Main section, an intermediate section (Pilot) and a central pilot body termed the RPL (Rich-Pilot-Lean) section. The Planar laser-induced fluorescence (PLIF) of OH radicals together with flame chemiluminescence imaging were employed for studying the local flame characteristics so as to be able to investigate the turbulence-flame interactions and the location of the reaction zone at the burner exit. Flames were investigated for three different fuel mixtures having hydrogen (H2)/methane (CH4) in vol. % concentration of 0/100, 25/75 and 50/50. The results show that the characteristics of the flames are clearly affected by the addition of hydrogen and the effects are expected due to the faster reaction rate, higher diffusivity and higher laminar burning velocity of H2. Enriching the flame with H2 at a constant global phi (ϕ) is found to shorten the total extension of the flame due to the higher laminar flame speed. The OH signal distribution becomes thicker and more pronounced due to the higher production of OH radicals, and the flame stabilization zone that is produced after the burner throat, moves further downstream. At a constant global ϕ in altering the RPL and the Pilot ϕ, similar changes for both 0/100 and 25/75 (in vol. %) of the H2/CH4 fuel mixtures can be observed. At a rich RPL ϕ, the secondary RPL flame contributes to the main flame and to determining the flame stabilization position. The flame stabilization zone located after the burner throat moves further downstream with an increase in the RPL ϕ. When the PFR (Pilot fuel ratio) increases, the extension of the flame shortens and the flame stabilization zone moves upstream. Combustion emissions were also determined so as to observe the effects of the H2 enrichment on the NOX level.
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Torii, Shuichi, Sze Man Simon Chan, and Toshiaki Yano. "Transport in Turbulent Jet Diffusion Flames With Annular Counterflow." In ASME 2001 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2001. http://dx.doi.org/10.1115/imece2001/htd-24258.
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Abstract The present study deals with the augmentation of the turbulent shear effect on transport in turbulent jet diffusion flames due to the presence of air-suction flow and the possibility of extending the flame blow-off limits through augmentation. The experimental apparatus employed here comprises a fuel nozzle placed at the center of a concentric annulus with an outer cylinder encompassing the nozzle. The fuel jet is allowed to eject upwards and turbulent jet diffusion flames are formed by igniting the jet, then by increasing the volume flow rate of the fuel. The annular counterflow technique was employed to augment the turbulent shear effect. It is found that (1) the augmentation of turbulent shear effect exerted on the shear layer formed between the jet flames and the opposed flow of air causes an increase in temperature of the cold fuel gas at the flame center and an extension of flame blowoff limits; (2) flame lift-off heights are suppressed; (3) the lift-off propensity of the diffusion flame is alleviated by such augmentation.
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Hariharan, P., and S. R. Gollahalli. "Characteristics of Partially Premixed Elliptic Burner Flames in Coflow-Velocity Air Streams." In ASME 2004 International Mechanical Engineering Congress and Exposition. ASMEDC, 2004. http://dx.doi.org/10.1115/imece2004-60336.
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This paper presents the results of an extension of the previous study where the effects of jet equivalence ratio and burner geometry on the characteristics of partially premixed propane/hydrogen/air flames at a coflow air velocity of 3 m/s were presented. The results here pertain to the experiments where the coflow velocity was doubled to understand the effects of coflow. Two different burner geometries (Circular, and 3:1 aspect ratio-AR elliptical burners) were used in the experiments with circular burner flames as baseline condition. During the study, the exit velocity was held constant at 20 m/s for all conditions. Stability tests indicated that circular burner flames were more stable than the 3:1AR elliptical burner flames at quiescent conditions. At 6 m/s coflow air velocity, stability of both the circular and the 3:1AR elliptic flames was enhanced. Circular burner flames were longer than 3:1AR elliptical burner flames. Introduction of 6 m/s coflow air velocity reduced the flame height. Global NO and CO emission indices decreased considerably after the introduction of coflow air in both burners. Peak temperature of circular burner flames was higher than that of 3:1AR elliptic burner at all conditions. Inflame concentration measurements were also taken in near-burner (25% flame height), midflame (50% flame height) and far-burner (75% flame height) regions.
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O’Connor, Jacqueline, and Vishal Acharya. "Development of a Flame Transfer Function Framework for Transversely Forced Flames." In ASME Turbo Expo 2013: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/gt2013-95900.
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This paper describes a framework for the development of a flame transfer function for transversely forced flames. While extensive flame transfer function measurements have been made for longitudinally forced flames, the disturbance field characteristics governing the flame response of a transversely forced flame are different enough to warrant separate investigation. In this work, we draw upon previous investigations of the flame disturbance pathways in a transversely forced flame to describe the underlying mechanisms that govern the behavior of the flame transfer function. Previous transverse forcing studies have shown that acoustic coupling in the nozzle region can result in both transverse and longitudinal acoustic fluctuations at the flame, and that the acoustic coupling is a function of combustor geometry, and hence, frequency. The results presented here quantify this coupling across a large range of frequencies using a velocity transfer function, FTL. The shape of the velocity transfer function gain indicates that there is strong acoustic coupling between the main combustor section and the nozzle at certain frequencies. Next, measured flame transfer functions are compared with results from theory. These theoretical results are derived from two level-set models of flame response to velocity disturbance fields, where velocity inputs are derived from experimental results. Data at several test conditions are presented and larger implications of this research are described with respect to gas turbine combustor design.
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Staufer, M., and J. Janicka. "Large Eddy Simulation of a Lean Gas Turbine Model Combustor." In ASME Turbo Expo 2009: Power for Land, Sea, and Air. ASMEDC, 2009. http://dx.doi.org/10.1115/gt2009-59725.
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Partially premixed flames although common on many technical devices are difficult to model in numerical simulations. In this paper a Large Eddy Simulation of a lean combustor is presented. To account for mixing effects in case of partially premixed combustion, a suitable extension to the well known coherent flame model (CFM) is applied. The turbulent reaction rate of the partially premixed flame is approximated by solving an additional transport equation for the flame surface density which accounts for flame wrinkling effects as well as for the creation and destruction of flame surface due to stretch and strain effects. The variation of stoichiometry in the flame is accounted for by using a suitable presumed PDF methodology. The pdf-model represents finite rate, as well as non-equilibrium chemistry effects in the flame. The model has been validated against experimental data. The results show an overall reasonable agreement with experimental data, both in profile shapes as well as peak values.
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Blanchard, Victorien P., Frédéric Roqué, Philippe Scouflaire, Christophe O. Laux, and Sébastien Ducruix. "Lean Flame Stabilization With Nanosecond Plasma Discharges in a Gas Turbine Model Combustor." In ASME Turbo Expo 2023: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2023. http://dx.doi.org/10.1115/gt2023-102621.
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Abstract This paper presents an experimental study of lean flames stabilization with nanosecond repetitively pulsed discharges. The two-stage, swirled-stabilized, multipoint injector BIMER operates at atmospheric pressure with methane-air mixtures in the present study. It is representative in its design of a realistic lean premixed prevaporized injector of gas turbine engines operated at a lab-scale level. The lean blow-off extension with plasma is characterized. The combustion efficiency and the pollutant emissions are quantified near blow-off with and without plasma for 50-kW flames. We show that it is possible to stabilize lean flames down to an equivalence ratio of 0.3, with less than 5 ppm of NOx emitted, thanks to NRP discharges with an electric power that represents less than 0.25% of the flame thermal power. This study also clearly shows that it is necessary to account for the plasma system integration at the early stage of the combustor design to fully benefit from the plasma stabilizing effects on the flame.
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Bentebbiche, Abdelhalim, and Denis Veynante. "Coherent Flame Model to Predict Formation Pollutants in Turbulent Premixed Flame." In ASME 2010 10th Biennial Conference on Engineering Systems Design and Analysis. ASMEDC, 2010. http://dx.doi.org/10.1115/esda2010-24466.
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The objective of this work is to analyze and to model the turbulent flames in the context of coherent flame model. We present a detailed description of equations and the flamelet regimes in turbulent premixed flame. A surface density models proposed here represents a good issue for numerical simulation. Extension of coherent flame model and homogenous stilled reactor model is proposed to consider the dynamics behavior of flame and pollutants formation. From the results of this work it is concluded that the coherent flame model allows surpassing difficulties of the turbulent reactive flow modeling. Calculations based on a semi-global kinetic scheme and flamelet formulation combined with a well stirred reactor analysis of the burnt gases are used and provided reasonably accurate values of CO and NO formation. Also, we have observed that CO is formed near the reaction zone (front flame) but emission of CO2, H2O and NO are formed in the hot gases.
Reports on the topic "Extension de flamme"
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Olsen and Fletcher. L52071 Literature Review Fuel-Air Mixing in Large Bore Natural Gas Engines. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), March 1999. http://dx.doi.org/10.55274/r0010949.
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Mixing is viewed as being problematic in many internal combustion engines, particularly large bore natural gas engines. In reviewing the literature an attempt is made to distinguish between the influences of mixing and turbulence, although for much of the published research the distinction is not made. Mixing is determined to have a major impact on engine efficiency, overall emissions, flame propagation, and cycle-to-cycle variations. The improvement of engine efficiency and overall emissions is concluded to be primarily due to the extension of the lean limit, a direct consequence of improved mixing. Test results from a study on propane combustion in a constant volume combustion chamber indicate that there is an optimum level of mixing for maximizing the flame propagation speed. In other words, the fastest flame speed occurs when there is some level of mixture heterogeneity, as opposed to a completely uniform mixture. A detailed literature review is carried out on air-fuel mixing in internal combustion engines, emphasizing application to direct injection large bore natural gas engines. The literature is separated into three broad categories, (1) the effects of mixing on engine performance, emissions, and combustion characteristics, (2) factors affecting mixing, and (3) mixing characterization.
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Wilson. PR-239-9525-E01 Integrated Test Plan. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), January 1996. http://dx.doi.org/10.55274/r0011046.
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In order to understand and eventually control formaldehyde emissions, it is necessary to investigate formaldehyde formation mechanisms and evaluate the applicability of these mechanisms to industrial gas engines. An extensive literature review was conducted to identify possible formaldehyde formation mechanisms, factors that favor these chemical mechanisms, and the relationships between various engine operating conditions and engine-out formaldehyde emissions. The literature review provided the following information on formaldehyde emissions: Formation and subsequent destruction of formaldehyde are necessary intermediate steps in the complete combustion of natural gas; Regions within the combustion chamber processed by propagating flames are not likely sources of formaldehyde; Identification of a distinct 'temperature window' where net formaldehyde formation occurs, provided that adequate oxygen and unburned hydrocarbons are present; Above the 'temperature window' formaldehyde is quickly destroyed, and below it formaldehyde mole fractions are frozen; and Emissions of formaldehyde from natural gas fired engines require that partial combustion, to some degree, take place in the cylinder. This finding is supported by results of equilibrium calculations of natural gas combustion product composition, which do not predict significant levels of formaldehyde. A number of publications have been produced from the integrated test plan body of work. Those publications include reports on the formaldehyde literature review, humidity test program, and the high pressure injection project and technical papers on formaldehyde literature review, high pressure injection, the tracer gas method, in-cylinder sampling, and humidity investigations. The work described in the humidity and high pressure injection reports is not covered in detail in this document. However, the results are discussed as needed to support data interpretation and conclusions. Includes a literature review of mixing and humidity effects as well as a spreadsheet of the test data.