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Artykuły w czasopismach na temat "Single compartment fires"
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Smith, Kevin T., i Elaine Kennedy Sutherland. "Fire-scar formation and compartmentalization in oak". Canadian Journal of Forest Research 29, nr 2 (1.02.1999): 166–71. http://dx.doi.org/10.1139/x98-194.
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Fire scars result from the death of the vascular cambium resulting from excessive heating, which exposes sapwood to infection and initiates the wood decay process. In southeastern Ohio, prescribed fires in April 1995 and 1997 scarred Quercus prinus L. and Q. velutina Lam. Low-intensity fires scorched bark and produced scars, primarily on the downslope side of the stem. Eighteen scorched trees (4-23 cm at DBH) were dissected in November 1997, 14 of which had fire scars. The vascular cambium beneath natural bark fissures was most vulnerable to injury. No charred or scorched wood was associated with scars of trees exposed to single fires; wood exposed by scars from the 1995 fire was charred by the 1997 fire. Consistent with the compartmentalization process, discoloration and whiterot occurred within compartment boundaries of wood present at the time of wounding. Scars from the prescribed fires were consistent in size and shape with scars in nearby oak trees previously hypothesized to have been burned prior to 1950.
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Wang, Yong, Jiachao Wu, Zhaohui Huang, Jian Jiang, Guanglin Yuan, Yajun Zhang, Yaqiang Jiang, Zhenxing Chen i Meng Zhou. "Experimental studies on continuous reinforced concrete slabs under single and multi-compartment fires with cooling phase". Fire Safety Journal 111 (styczeń 2020): 102915. http://dx.doi.org/10.1016/j.firesaf.2019.102915.
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Zhou, Yang, Rongwei Bu, Junhui Gong, Zhongyang Geng, Huiai Fu i Liang Yi. "Effect of Ambient Wind Speed on Pressure Distribution and Smoke Movement in Single and Multiple Compartment Fires". Combustion Science and Technology 191, nr 8 (5.10.2018): 1354–79. http://dx.doi.org/10.1080/00102202.2018.1527325.
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Miao, Lei, i Cheuk Lun Chow. "Thermal behavior of window plume generated by fully developed compartment fires in single-skin and double-skin façade scenarios". International Journal of Thermal Sciences 153 (lipiec 2020): 106359. http://dx.doi.org/10.1016/j.ijthermalsci.2020.106359.
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Merci, Bart, i Paul Vandevelde. "Comparison of calculation methods for smoke and heat evacuation for enclosure fires in large compartments". Thermal Science 11, nr 2 (2007): 181–96. http://dx.doi.org/10.2298/tsci0702181m.
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A comparative study is presented of different calculation methods with respect to the evacuation of smoke and heat in the case of enclosure fires in large compartments. These methods range from manual calculations, based on empirical formulae, over zone modeling to the use of computational fluid dynamics. The focus is on large single storey compartments. The differences between results obtained with the examined methods are discussed. .
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Wilson, C. J., i J. C. Callaway. "Coupled Oscillator Model of the Dopaminergic Neuron of the Substantia Nigra". Journal of Neurophysiology 83, nr 5 (1.05.2000): 3084–100. http://dx.doi.org/10.1152/jn.2000.83.5.3084.
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Calcium imaging using fura-2 and whole cell recording revealed the effective location of the oscillator mechanism on dopaminergic neurons of the substantia nigra, pars compacta, in slices from rats aged 15–20 days. As previously reported, dopaminergic neurons fired in a slow rhythmic single spiking pattern. The underlying membrane potential oscillation survived blockade of sodium currents with TTX and was enhanced by blockade of voltage-sensitive potassium currents with TEA. Calcium levels increased during the subthreshold depolarizing phase of the membrane potential oscillation and peaked at the onset of the hyperpolarizing phase as expected if the pacemaker potential were due to a low-threshold calcium current and the hyperpolarizing phase to calcium-dependent potassium current. Calcium oscillations were synchronous in the dendrites and soma and were greater in the dendrites than in the soma. Average calcium levels in the dendrites overshot steady-state levels and decayed over the course of seconds after the oscillation was resumed after having been halted by hyperpolarizing currents. Average calcium levels in the soma increased slowly, taking many cycles to achieve steady state. Voltage clamp with calcium imaging revealed the voltage dependence of the somatic calcium current without the artifacts of incomplete spatial voltage control. This showed that the calcium current had little or no inactivation and was half-maximal at −40 to −30 mV. The time constant of calcium removal was measured by the return of calcium to resting levels and depended on diameter. The calcium sensitivity of the calcium-dependent potassium current was estimated by plotting the slow tail current against calcium concentration during the decay of calcium to resting levels at −60 mV. A single compartment model of the dopaminergic neuron consisting of a noninactivating low-threshold calcium current, a calcium-dependent potassium current, and a small leak current reproduced most features of the membrane potential oscillations. The same currents much more accurately reproduced the calcium transients when distributed uniformly along a tapering cable in a multicompartment model. This model represented the dopaminergic neuron as a set of electrically coupled oscillators with different natural frequencies. Each frequency was determined by the surface area to volume ratio of the compartment. This model could account for additional features of the dopaminergic neurons seen in slices, such as slow adaptation of oscillation frequency and may produce irregular firing under different coupling conditions.
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Gorassini, Monica, Torsten Eken, David J. Bennett, Ole Kiehn i Hans Hultborn. "Activity of Hindlimb Motor Units During Locomotion in the Conscious Rat". Journal of Neurophysiology 83, nr 4 (1.04.2000): 2002–11. http://dx.doi.org/10.1152/jn.2000.83.4.2002.
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This paper compares the activity of hindlimb motor units from muscles mainly composed of fast-twitch muscle fibers (medial and lateral gastrocnemius: MG/LG, tibialis anterior: TA) to motor units from a muscle mainly composed of slow-twitch muscle fibers (soleus: SOL) during unrestrained walking in the conscious rat. Several differences in the activation profiles of motor units from these two groups of muscles were observed. For example, motor units from fast muscles (e.g., MG/LG and TA) fired at very high mean frequencies of discharge, ranging from 60 to 100 Hz, and almost always were recruited with initial doublets or triplets, i.e., initial frequencies ≥100 Hz. In contrast, the majority of SOL units fired at much lower mean rates of discharge, ≈30 Hz, and had initial frequencies of only 30–60 Hz (i.e., there were no initial doublets/triplets ≥100 Hz). Thus the presence of initial doublet or triplets was dependent on the intrinsic properties of the motor unit, i.e., faster units were recruited with a doublet/triplet more often than slower units. Moreover, in contrast to units from the slow SOL muscle, the activity of single motor units from the fast MG/LG muscle, especially units recruited midway or near the end of a locomotor burst, was unrelated to the activity of the remainder of the motoneuron pool, as measured by the corresponding gross-electromyographic (EMG) signal. This dissociation of activity was suggested to arise from a compartmentalized recruitment of the MG/LG motoneuron pool by the rhythm-generating networks of the spinal cord. In contrast, when comparing the rate modulation of simultaneously recorded motor units within a single LG muscle compartment, the frequency profiles of unit pairs were modulated in a parallel fashion. This suggested that the parent motoneurons were responsive to changes in synaptic inputs during unrestrained walking, unlike the poor rate modulation that occurs during locomotion induced from brain stem stimulation. In summary, data from this study provide evidence that the firing behavior of motor units during unrestrained walking is influenced by both the intrinsic properties of the parent motoneuron and by synaptic inputs from the locomotor networks of the spinal cord. In addition, it also provides the first extensive description of motor-unit activity from different muscles during unrestrained walking in the conscious rat.
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Smith, Robert G., i Noga Vardi. "Simulation of the Aii amacrine cell of mammalian retina: Functional consequences of electrical coupling and regenerative membrane properties". Visual Neuroscience 12, nr 5 (wrzesień 1995): 851–60. http://dx.doi.org/10.1017/s095252380000941x.
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AbstractThe Aii amacrine cell of mammalian retina collects signals from several hundred rods and is hypothesized to transmit quantal “single-photon” signals at scotopic (starlight) intensities. One problem for this theory is that the quantal signal from one rod when summed with noise from neighboring rods would be lost if some mechanism did not exist for removing the noise. Several features of the Aii might together accomplish such a noise removal operation: The Aii is interconnected into a syncytial network by gap junctions, suggesting a noise-averaging function, and a quantal signal from one rod appears in five Aii cells due to anatomical divergence. Furthermore, the Aii contains voltage-gated Na+ and K+ channels and fires slow action potentials in vitro, suggesting that it could selectively amplify quantal photon signals embedded in uncorrelated noise. To test this hypothesis, we simulated a square array of AII somas (Rm = 25,000 Ohm-cm2) interconnected by gap junctions using a compartmental model. Simulated noisy inputs to the Aii produced noise (3.5 mV) uncorrelated between adjacent cells, and a gap junction conductance of 200 pS reduced the noise by a factor of 2.5, consistent with theory. Voltage-gated Na+ and K+ channels (Na+: 4 nS, K+: 0.4 nS) produced slow action potentials similar to those found in vitro in the presence of noise. For a narrow range of Na+ and coupling conductance, quantal photon events (-5–10 mV) were amplified nonlinearly by subthreshold regenerative events in the presence of noise. A lower coupling conductance produced spurious action potentials, and a greater conductance reduced amplification. Since the presence of noise in the weakly coupled circuit readily initiates action potentials that tend to spread throughout the AII network, we speculate that this tendency might be controlled in a negative feedback loop by up-modulating coupling or other synaptic conductances in response to spiking activity.
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Chen, Andrew N., i C. Daniel Meliza. "Phasic and tonic cell types in the zebra finch auditory caudal mesopallium". Journal of Neurophysiology 119, nr 3 (1.03.2018): 1127–39. http://dx.doi.org/10.1152/jn.00694.2017.
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The caudal mesopallium (CM) is a cortical-level area in the songbird auditory pathway where selective, invariant responses to familiar songs emerge. To characterize the cell types that perform this computation, we made whole cell recordings from brain slices in juvenile zebra finches ( Taeniopygia guttata) of both sexes. We found three groups of putatively excitatory neurons with distinct firing patterns. Tonic cells produced sustained responses to depolarizing step currents, phasic cells produced only a few spikes at the onset, and an intermediate group was also phasic but responded for up to a few hundred milliseconds. Phasic cells had smaller dendritic fields, higher resting potentials, and strong low-threshold outward rectification. Pharmacological treatment with voltage-gated potassium channel antagonists 4-aminopyridine and α-dendrotoxin converted phasic to tonic firing. When stimulated with broadband currents, phasic cells fired coherently with frequencies up to 20–30 Hz, whereas tonic neurons were more responsive to frequencies around 0–10 Hz. The distribution of peak coherence frequencies was similar to the distribution of temporal modulation rates in zebra finch song. We reproduced these observations in a single-compartment biophysical model by varying cell size and the magnitude of a slowly inactivating, low-threshold potassium current ( ILT). These data suggest that intrinsic dynamics in CM are matched to the temporal statistics of conspecific song. NEW & NOTEWORTHY In songbirds, the caudal mesopallium is a key brain area involved in recognizing the songs of other individuals. This study identifies three cell types in this area with distinct firing patterns (tonic, phasic, and intermediate) that reflect differences in cell size and a low-threshold potassium current. The phasic-firing neurons, which do not have a counterpart in mammalian auditory cortex, are better able to follow rapid modulations at the frequencies found in song.
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Rhodes, Paul A. "Recoding Patterns of Sensory Input: Higher-Order Features and the Function of Nonlinear Dendritic Trees". Neural Computation 20, nr 8 (sierpień 2008): 2000–2036. http://dx.doi.org/10.1162/neco.2008.04-07-511.
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Here analytical and simulation results are presented characterizing the recoding arising when overlapping patterns of sensor input impinge on an array of model neurons with branched thresholded dendritic trees. Thus, the neural units employed are intended to capture the integrative behavior of pyramidal cells that sustain isolated Na+ or NMDA spikes in their branches. Given a defined set of sensor vectors, equations were derived for the probability of firing of both branches and neurons and for the expected overlap between the neural firing patterns triggered by two afferent patterns of given overlap. Thus, both the sparseness of the neural representation and the orthogonalization of overlapping vectors were computed. Simulations were then performed with an array of 1000 neurons comprising 30,000 branches to verify the analytical results and confirm their applicability to systems (which include any practicable artificial system) in which the combinatorically possible branches and neurons are severely subsampled. A means of readout and a measure of discrimination performance were provided so that the accuracy of discrimination among overlapping sensor vectors could be optimized as a function of neuron structure parameters. Good performance required both orthogonalization of the afferent patterns, so that discrimination was accurate and free of interference, and maintenance of a minimum level of neural activity, so that some neurons fired in response to each sensor pattern. It is shown that the discrimination performance achieved by arrays of neurons with branched dendritic trees could not be reached with single-compartment units, regardless of how many of the latter are used. The analytical results furnish a benchmark against which to measure further enhancements in the performance of subsequent simulated systems incorporating local neural mechanisms which, while often less amenable to closed-form analysis, are ubiquitous in biological neural circuitry.
Rozprawy doktorskie na temat "Single compartment fires"
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Tsai-Hui, Chao, i 趙彩惠. "The development of zone fire model for single compartment". Thesis, 1999. http://ndltd.ncl.edu.tw/handle/74051789121562573281.
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碩士國立交通大學
機械工程系
87
The main purpose of this thesis is to simulate Wang's "Full-Scale Room Fire Tests", which comply with ISO 9705 standard. The "Zone Model" approach is applied by this thesis to set up the combustion model to calculate the flame height and entrainment. Also an outline of the phenomena is given for a room fire. An interactive code is developed. From a series of screens, the user can input the geometry of fire room, the geometry and position of vent and the characteristic of combustion, then can get the temperature of fire room and the height of smoke layer. A comparison between the simulation results and the experimental data is given. However, the present code does not consider thematerial of the ceiling and walls, the variation of thermal properties of gas during the period of simulation time, and the effect of fan. These effects should be included in the modified version of this code.
Części książek na temat "Single compartment fires"
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Li, Qiang, Jinmei Li, Shijing Ren i Jiaqing Zhang. "Smoke Filling in a Confined Compartment with Single Ceiling Vent". W Fire Science and Technology 2015, 783–91. Singapore: Springer Singapore, 2016. http://dx.doi.org/10.1007/978-981-10-0376-9_80.
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Magalhães, Manuela R., Selma B. Pena, Natália S. Cunha, Luísa M. Franco i Ana Müller. "Transforming Rural Landscape towards Fire Resilience and Landscape Sustainability". W Advances in Forest Fire Research 2022, 422–30. Imprensa da Universidade de Coimbra, 2022. http://dx.doi.org/10.14195/978-989-26-2298-9_68.
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After the fires occurred in 2017 and 2018 in Portugal, the imperative need to plan for sustainable and fire resilient landscapes led to the implementation of the Landscape Transformation Program. However, it is still lacking a landscape planning methodology to achieve those resilient landscapes. This paper presents a landscape plan for a fire-prone landscape located in the Centre region of continental Portugal - Serras da Lousã e Açor. This landscape is characterised by steep slopes (70% of the total area) and is dominated by highly combustible coverings, such as eucalyptus (27.89 %), maritime pine (28.06 %), other coniferous (10.08 %) and shrubs (18.91 %). Fires have occurred frequently and 96 % of the case study's total area was burned between 1975 and 2020. The landscape plan here presented was based on the FIRELAN model and goes a step further by proposing a progressive landscape transformation. FIRELAN integrates fire resilience, ecological sustainability, and economic viability. In this model, the landscape components, which can be physical, biological or cultural, are organised in two main infrastructures - the Ecological Network and the Fire Resilient Landscape Infrastructure - and in Complementary Areas. The Ecological Network ensures the ecological functioning of the landscape by emphasising the quality or potentiality of biophysical components, in articulation with the nature conservation and at-risk areas, underlying the provision of multiple functions valuable to society. The Fire Resilient Landscape Infrastructure promotes the landscape discontinuities related to land morphology, in association with less combustible land uses, and includes the cultural management in the urban-rural interface, roads, and power grid. This infrastructure is divided in two, the Primary and the Secondary Fire Resilient Landscape Infrastructures. The last one includes the areas with slopes greater than 25%, located outside the Fire Resilient Primary Infrastructure. As to the Complementary Areas, these correspond to the interstices (compartments with slopes less than 25%) of the infrastructures. Since these areas have low ecological value, they can allocate more artificial land uses. The implementation of the landscape plan is defined in two temporal phases: the landscape plan for the Scenario 2030, which consists on the implementation of the Primary Fire Resilient Landscape Infrastructure (51%), and the landscape plan for the Scenario 2050, that adds the implementation of the Secondary Fire Resilient Landscape Infrastructure (37%) and Complementary Areas (9 %). This landscape plan represents a paradigm shift from a landscape dominated by eucalyptus and maritime pine to a dominant forest of native species (such as oaks), archetypical species (such as chestnut the walnut - both for wood or fruit - the wild cherry and others) and also riparian species (alder, willows, poplar, ash, elm, etc.). Differentiating the final proposal into two phases makes it possible to distinguish implementation priorities, since the application of the model implies a substantial transformation of the current landscape, with high implementation costs. The payment for ecosystem services to the landowners during the paradigm transition period, which is expected to be 20 to 30 years, is recommended to allow the plan implementation.
Streszczenia konferencji na temat "Single compartment fires"
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Wakatsuki, K., B. Ringwelski i J. G. Quintiere. "Fire Behavior in a Poorly Ventilated Compartment". W ASME 2001 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2001. http://dx.doi.org/10.1115/imece2001/htd-24244.
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Abstract The fire behavior of heptane burning in a poorly ventilated compartment was studied. The diameter of the heptane pan fires were varied and the ventilation opening size and location were adjusted. Two kinds of compartment fire experiment were conducted: (1) horizontal slits at the top and bottom of a wall, and (2) a single vent at the roof. Temperature, oxygen, fuel mass loss rate and differential pressure were measured. Extinction was studied with an oxygen meter to find the minimum oxygen concentration in the compartment achieved in ventilation-controlled fires. Extinguishments due to ventilation or complete fuel consumption was distinguished. Flow exchange was measured by differential pressure transducers. Particularly, flow exchange of ceiling vent was examined by calculation of flooding pressure difference, which will allow bi-directional flow. The wall vent case had oscillatory combustion (puffing), which sometimes leads to an increase in fire amplitude followed by extinction. This was not observed for the ceiling vent case. Video recording of the flame was conducted through a glass on sidewall. The fire behavior varied from conditions in which the flame extinguishes to cases of steady burning. In some cases, “ghosting flames” were observed.
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Kameel, Ramiz, i Essam E. Khalil. "Numerical Simulation of Fires in Ventilated Compartment". W ASME 2004 Heat Transfer/Fluids Engineering Summer Conference. ASMEDC, 2004. http://dx.doi.org/10.1115/ht-fed2004-56047.
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This study is the analytical investigation of transient flow characteristics in a ventilated compartment fire. This study aims at enhancing the understanding of fire propagation in the compartment and its influence on the air flow characteristics. The present paper discusses the results of different ventilation scenarios for a single fire scenario. It is recommended to use the smoke extract fans in designated locations in the spaces that could be exposed to the fire hazards. Corridor smoke extract fan provides the safe escape for the occupancy. Quantitative parametric studies are carried out for various situations, to enhance our knowledge about the fire behavior. The critical time for the safe escaping of occupancy from the fire starting is discussed in the present work. Also, it is found that, the fire field models based on CFD are useful tools that can greatly support this target.
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Gernay, Thomas, i Negar E. Khorasani. "Demonstrating Performance-Based Fire Design of Composite Buildings". W IABSE Congress, New York, New York 2019: The Evolving Metropolis. Zurich, Switzerland: International Association for Bridge and Structural Engineering (IABSE), 2019. http://dx.doi.org/10.2749/newyork.2019.0339.
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<p>Performance-Based Fire Engineering (PBFE) is gaining traction in the US, with the aim to provide safe, resilient and cost-effective design solutions for structural systems in our evolving communities. Steel-framed buildings with composite steel-concrete floors are widely used in practice and offer opportunities for achieving robust fire performance through PBFE. This paper demonstrates the design process, computational modeling approaches, and main assumptions for PBFE of steel-concrete composite buildings using a streamlined and systematic methodology. Performance expectations are explicitly spelled out at the outset of the process. A set of design fires are generated using zone models based on high percentiles of the fuel load. Then, the thermal-structural response is modeled using nonlinear finite element analyses. Design alternatives are evaluated against the predefined performance expectations. While the prescriptive code design does not survive until burnout, PBFE alternatives can survive the fire, adopting selected structural upgrades and an optimized allocation of the thermal insulation on the steel members. The activation of tensile membrane action in the fire-exposed composite floor is captured by the model. Single bay models are compared to full building models, showing the beneficial contribution of the system restraints provided steel mesh continuity is ensured over the girders. Thus, the single slab model provides conservative results at lesser computational cost. The full building model allows investigating robustness under extreme scenarios such as multi- compartment fires or multi-hazard scenarios with fire following a column loss. Adoption of this design process by structural fire engineers can lead to robust PBFE designs with explicit evaluation of the response under a range of extreme events, for a demonstrated performance level that is pre-agreed between the stakeholders.</p>
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McGrattan, Kevin B., Michelle Donnelly, Anthony Hamins, Eric Johnnson, Alex Maranghides, George Mulholland, Tom Ohlemiller, John Widmann i Jiann Yang. "Validation Experiments of Large Compartment Fires". W ASME 2003 International Mechanical Engineering Congress and Exposition. ASMEDC, 2003. http://dx.doi.org/10.1115/imece2003-41384.
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In cooperation with the fire protection engineering community, a computational fire model, Fire Dynamics Simulator (FDS), is being developed at NIST to study fire behavior and to evaluate the performance of fire protection systems in buildings. The software was released into the public domain in 2000, and since then has been used for a wide variety of analyses by fire protection engineers. An on-going need is to develop and validate new sub-models. Fire experiments are conducted for a variety of reasons, and model predictions of these experiments over the past few decades have gradually improved. However, as the models become more detailed, so must the measurements. The bulk of available large scale test data consist of temperature (thermocouple) measurements made at various points above a fire or throughout an enclosure. While it is useful to compare model predictions with these measurements, one can only gauge how closely the model reproduces the given data. There is often no way to infer why the model and experiment disagree, and thus no way to improve the model. Also, it is difficult to separate various physical phenomena in a large scale fire test so that combustion, radiation and heat transfer algorithms can be evaluated independently. For example, the heat release rate of the fire governs the rate at which energy is added to the system, convective and radiative transport distribute the energy throughout, and thermal conduction drains the system of some of the energy. The measured value of a temperature, heat flux, or gas concentration at any one point depends on all the physical processes, and uncertainties in each phase of the calculation tend to combine in a non-linear way impacting the prediction.
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Becker, W., Xinghuo Yu, Jiyuan Tu i E. Lee. "Single compartment fire risk analysis using a fuzzy neural network". W The 2006 IEEE International Joint Conference on Neural Network Proceedings. IEEE, 2006. http://dx.doi.org/10.1109/ijcnn.2006.246957.
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Khalil, Essam E. "Mathematical Modelling of Fire and Smoke Characteristics in Ventilated Rooms". W ASME 2009 Heat Transfer Summer Conference collocated with the InterPACK09 and 3rd Energy Sustainability Conferences. ASMEDC, 2009. http://dx.doi.org/10.1115/ht2009-88296.
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This paper presents a preliminary investigation of transient flow characteristics and heat release in a ventilated compartment fire. This study aims at enhancing current understanding of fire propagation in the compartment and its influence on the air flow characteristics. The present paper demonstrated through the application of numerical techniques the results of different ventilation scenarios for single fire scenario. It is recommended to use the smoke extract fans in designated locations in the spaces that could be exposed to the fire hazards. Corridor smoke extract fan provides the safe escape for the occupancy. Quantitative parametric studies are carried out for various situations, to enhance our knowledge about the fire behaviour. The fire field models based on CFD are useful tools that can greatly support this target.
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Perez, Rodrigo, i Verónica Alonso. "A unique application and point of truth for Naval Architecture Calculations". W SNAME 5th World Maritime Technology Conference. SNAME, 2015. http://dx.doi.org/10.5957/wmtc-2015-108.
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Many tools handle with the calculation of compartment definition, hydrostatics, intact and damage stability and power prediction, but these calculations are separated from the rest of ship CAD/CAM tools. Ship designers need to work closely with the shipyards, in a complex and distributed environment making necessary to have suitable tools at early design stages to ensure profitable projects. Naval architecture is handled in FORAN with a revolutionary approach, where integration and advanced features are the relevant characteristics in a single and complete set of applications that are used in conjunction to other disciplines, from concept design to operation. This new approach groups the former modules for naval architecture available in FORAN from many years, is intuitive and user-friendly. The information is stored in a database instead of a wide set of files. As regards this feature, there are two different alternatives depending on the scope of the project. If the ship designer wants to calculate only naval architecture calculations, the solutions is based on a SQLITE database suitable for a standalone application. This approach benefits a ship design office, in the study of different design alternatives very quickly but having a complete control of them. The other option is integrating the Naval Architecture with the rest of FORAN design disciplines, in a single database based in Oracle. In this case, the great benefit comes from the single truth of data from concept design to operation, which ensures dramatically the reduction of errors and re-work. After the definition of compartments in 3D, by using a very fast application, the module guides the user through the naval architecture calculations with a tree of elements very intuitive, with powerful key algorithms and with a solid representation of spaces. The definition of the necessary entities to make any kind of calculation is very fast. For the intact stability a set of standard stability criteria is provided. It is based in a quick definition of loading conditions, initial situations, flooding conditions and compartment subdivisions. And for the evaluation of the damage stability a set of standard stability criteria are also provided, following deterministic and probabilistic approaches. With these tools any naval architect is able to make very fast all the necessary studies to assure the stability regulations are complied with.
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Martini, Francesco, Andrea Quattrini i Stefano Ricci. "Fire simulation in railway tunnels: towards the design requirements for emergency exits". W 7th International Conference on Road and Rail Infrastructure. University of Zagreb Faculty of Civil Engineering, 2022. http://dx.doi.org/10.5592/co/cetra.2022.1382.
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Emergency exits are one of the most critical elements during fire safety design in railway tunnels, allowing for a quick evacuation from the endangered area to the nearest safe location. At the present-state, there is lack of a comprehensive regulation framework for the design of the ventilation systems protecting the exits from smoke and other by-products during a tunnel fire and the design is normally case-tailored. With the ultimate goal of finding the most appropriate design requirements as the main parameters involved vary, this paper discusses the simulation of two scenarios identified as highly critical for a mixed traffic line: a 10 MW fire of a passenger couch and a 250 MW fire of a freight wagon. The method used is the Computational Fluid Dynamics (CFD) supported by the Fire Dynamics Simulator (FDS). The key requirement is the minimum airflow needed to keep the exits safe according to the variability of parameters, such as position of fire, wind, single or twin tunnel. The scenarios are a short cross-connection between single-track twin tunnels and a connection to a safe zone in a double-track single tunnel. In each case, temperature, pressure and smoke entering the compartment demonstrate to be relevant parameters affecting the results. The results of an extensive simulation campaign pave the ground for next developments aimed at setup a design handbook covering a large set of infrastructure and operation conditions represent a step ahead a recognized standards in railway tunnels design.
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Flouros, Michael, Georgios Iatrou, Kyros Yakinthos, Francois Cottier i Markus Hirschmann. "Two-Phase Flow Heat Transfer and Pressure Drop in Horizontal Scavenge Pipes in an Aero Engine". W ASME Turbo Expo 2014: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/gt2014-25011.
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In modern aero engines the lubrication system plays a key role due to the demand for high reliability. Oil is used not only for the lubrication of bearings, gears or seals, but it also removes large amounts of the generated heat. Also, air from the compressor at elevated temperature is used for sealing the bearing chambers and additional heat is introduced into the oil through radiation, conduction and convection from the surroundings. The impact of excessive heat on the oil may lead to severe engine safety and reliability problems which can range from oil coking (carbon formation) to oil fires. Coking may lead to a gradual blockage of the oil tubes and subsequently increase the internal bearing chamber pressure. As a consequence, oil may migrate through the seals into the turbo machinery and cause contamination of the cabin air or ignite and cause failure of the engine. It is therefore very important for the oil system designer to be capable to predict the system’s functionality. Coking or oil ignition may occur not only inside the bearing chamber but also in the oil pipes which carry away the air and oil mixture from the bearing chamber. Bearing chambers usually have one pipe (vent pipe) at the top of the chamber and also one pipe (scavenge pipe) at the bottom which is attached to a scavenge pump. The vent pipe enables most of the sealing air to escape thus avoid over-pressurization in the bearing compartment. In a bearing chamber sealing air is the dominant medium in terms of volume occupation and also the in terms of causing expansion phenomena. The scavenge pipe carries away most of the oil from the bearing chamber but some air is also carried away. The heat transfer in vent pipes was investigated by Busam [1], [2]. Busam has experimentally developed a Nusselt number correlation for an annular flow in a vent pipe. For the heat transfer predictions in scavenge pipes no particular Nusselt number correlation exist. This paper intends to close the gap in this area. As part of the European Union funded research programme ELUBSYS (Engine LUBrication System TechnologieS), an attempt was done to simplify the oil system’s architecture. In order to better understand the flow in scavenge pipes, high speed video was taken in two sections of the pipe (vertical and horizontal). In the vertical section the flow was a wavy annular falling film whereas the flow in the horizontal section was a an unsteady wavy stratified/slug flow. Heat transfer has been investigated in the horizontal section of the scavenge pipe, leaving the investigation on the vertical section for later. Thanks to the provided extensive instrumentation, the thermal field in, on and around the pipe was recorded, evaluated and also numerically modeled using ANSYS CFX version 14 [23]. Brand new correlations for two-phase flow heat transfer (Nusselt number) and for pressure drop (friction coefficient) in horizontal scavenge pipes are the result of this work. The Nusselt number correlation has been developed in such a way that smooth transition (i.e. no discontinuity) from two-phase into single phase flow is observed. This work was funded and conducted within the 7th EU Frame Programme for Aeronautics and Transport (AAT.2008.4.2.3).
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Ohno, Shuji, Takashi Takata i Yuji Tajima. "Evaluation of Sodium Pool Fire and Thermal Consequence in Two-Cell Configuration". W 2016 24th International Conference on Nuclear Engineering. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/icone24-61095.
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Evaluation of accidental sodium leak, combustion, and its thermal consequence is one of the important issues to be assessed in the field of sodium-cooled fast reactor (SFR) since the liquid sodium is chemically active and might give thermal load to plant building structure due to its exothermic reaction with oxygen in air atmosphere. Therefore, many experimental investigations and numerical simulation tools development have been and still now are being carried out to understand the details of sodium fire behaviors and to contribute to the investigation and preparation of appropriate mitigation measures in the plant design. From various kinds of sodium fire situations, the present paper treats the sodium pool fire and subsequent heat transfer behavior in air atmosphere two-cell geometry both experimentally and analytically because such two-cell configuration is considered as the typical one to possess important characteristic of multi-compartment system seen in an actual plant. Main description of this paper consists of a sodium pool fire experiment that was performed in a rectangular-shaped two-cell system with an opening between the cells, and the discussion of the experimental results. Inner volume of the experimental cells is about 70 m3. The amount of used sodium and the prepared pool surface area in the experiment are about 55 kg and 2.25 m2, respectively. The experiment has provided the temperature data measured in more than 100 positions for atmospheric gas and structures other than the data of oxygen concentration and suspended sodium aerosols concentration in the cells. The analyses of the measured data clarify the basic characteristics of sodium pool combustion and consequential heat and mass transfer in the cells, for instance, suggesting several features of multidimensional thermal-hydraulic behaviors such as thermal stratification near the opening between the two cells. In the discussion, numerical analysis using a lumped-parameter based zonal model safety analysis code ‘SPHINCS’ and the comparison of its results with the experimental data are also carried out to investigate the validity and applicability of the code to this type of sodium fire situation.
Raporty organizacyjne na temat "Single compartment fires"
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Weinschenk, Craig, i Keith Stakes. Analysis of Search and Rescue Tactics in Single-Story Single-Family Homes Part III: Tactical Considerations. UL's Fire Safety Research Institute, maj 2022. http://dx.doi.org/10.54206/102376/xsla7995.
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Prior full-scale fire service research on the residential fireground has focused the impact of ventilation and suppression tactics on fire dynamics. This study builds upon prior research by conducting 21 experiments in two identical purpose-built single-story, single-family residential structures to quantify the impact of how search and rescue tactics are coupled with ventilation and suppression actions and timing. Each fully furnished structure included four bedrooms, 2 bathrooms and an open-floor kitchen and living room. The structures were instrumented to quantify post-ignition toxic gas and thermal conditions. Temperature, velocity, and pressure were measured to evaluate the fire dynamics. Gas concentrations and heat fluxes were measured to quantify toxic and thermal exposures. Eleven experiments examined bedroom fires, eight examined kitchen fires, and two examined living room fires. Across this series of experiments, the impact of isolation of fire and non-fire compartments, the timing of search actions relative to suppression actions, and the influence of isolation, elevation, and path of travel during rescue were examined with respect to firefighter safety and occupant tenability. Similar to previous experiments in both purpose-built and acquired structure, the data showed that prior intervention locations lower in elevation and/or behind closed doors had lower toxic gas and thermal exposures compared to locations at higher elevations or locations that were not isolated. Lower elevations were also shown to have lower toxic gas and thermal exposures during the removal of occupants as part of rescue operations. For scenarios where search operations occurred prior to suppression, isolation of spaces from flow paths connected to the fire compartment was shown to be effective at reducing the thermal operating class for firefighters and the toxic and thermal exposure rates compared to spaces that were not isolated. Following isolation, exterior ventilation was found to further reduce the toxic gas and thermal exposures in the protected space. Suppression, from either interior and exterior positions, was effective at reducing the thermal operating class for searching firefighters and the rate of thermal exposure increase to occupants. Following suppression, additional exterior ventilation increased the rate at which gas concentrations returned to pre-ignition levels.
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Weinschenk, Craig. Analysis of Search and Rescue Tactics in Single-Story Single-Family Homes Part I: Bedroom Fires. UL's Fire Safety Research Institute, maj 2022. http://dx.doi.org/10.54206/102376/dptn2682.
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Prior full-scale fire service research on the residential fireground has focused the impact of ventilation and suppression tactics on fire dynamics. This study builds upon prior research by conducting 11 experiments a purpose-built single-story, single-family residential structure to quantify the im- pact of how search and rescue tactics are coupled with ventilation and suppression actions and timing. Each fully furnished structure included four bedrooms, 2 bathrooms and an open-floor kitchen and living room. The structures were instrumented to quantify post-ignition toxic gas and thermal conditions. Temperature, velocity, and pressure were measured to evaluate the fire dynamics. Gas concentrations and heat fluxes were measured to quantify toxic and thermal exposures. Across this series of experiments, the impact of isolation of fire and non-fire compartments, the timing of search actions relative to suppression actions, and the influence of isolation, elevation, and path of travel during rescue were examined with respect to firefighter safety and occupant tenability. Similar to previous experiments in both purpose-built and acquired structure, the data showed that prior intervention locations lower in elevation and/or behind closed doors had lower toxic gas and thermal exposures compared to locations at higher elevations or locations that were not isolated. Lower elevations were also shown to have lower toxic gas and thermal exposures during the removal of occupants as part of rescue operations. For scenarios where search operations occurred prior to suppression, isolation of spaces from flow paths connected to the fire compartment was shown to be effective at reducing the thermal operating class for firefighters and the toxic and thermal exposure rates compared to spaces that were not isolated. Following isolation, exterior ventilation was found to further reduce the toxic gas and thermal exposures in the protected space. Suppression, from either interior and exterior positions, was effective at reducing the thermal operating class for searching firefighters and the rate of thermal exposure increase to occupants. Following suppression, additional exterior ventilation increased the rate at which gas concentrations returned to pre-ignition levels.
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Weinschenk, Craig, i Jack Regan. Analysis of Search and Rescue Tactics in Single-Story Single-Family Homes Part II: Kitchen and Living Room Fires. UL's Fire Safety Research Institute, maj 2022. http://dx.doi.org/10.54206/102376/zkxw6893.
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Prior full-scale fire service research on the residential fireground has focused the impact of ventilation and suppression tactics on fire dynamics. This study builds upon prior research by conducting 10 experiments a purpose-built single-story, single-family residential structure to quantify the im- pact of how search and rescue tactics are coupled with ventilation and suppression actions and timing. Each fully furnished structure included four bedrooms, 2 bathrooms and an open-floor kitchen and living room. The structures were instrumented to quantify post-ignition toxic gas and thermal conditions. Temperature, velocity, and pressure were measured to evaluate the fire dynamics. Gas concentrations and heat fluxes were measured to quantify toxic and thermal exposures. Across this series of experiments, the impact of isolation of fire and non-fire compartments, the timing of search actions relative to suppression actions, and the influence of isolation, elevation, and path of travel during rescue were examined with respect to firefighter safety and occupant tenability. Similar to previous experiments in both purpose-built and acquired structure, the data showed that prior intervention locations lower in elevation and/or behind closed doors had lower toxic gas and thermal exposures compared to locations at higher elevations or locations that were not isolated. Lower elevations were also shown to have lower toxic gas and thermal exposures during the removal of occupants as part of rescue operations. For scenarios where search operations occurred prior to suppression, isolation of spaces from flow paths connected to the fire compartment was shown to be effective at reducing the thermal operating class for firefighters and the toxic and thermal exposure rates compared to spaces that were not isolated. Following isolation, exterior ventilation was found to further reduce the toxic gas and thermal exposures in the protected space. Suppression, from either interior and exterior positions, was effective at reducing the thermal operating class for searching firefighters and the rate of thermal exposure increase to occupants. Following suppression, additional exterior ventilation increased the rate at which gas concentrations returned to pre-ignition levels.
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Weinschenk, Craig, Keith Stakes i Robin Zevotek. Impact of Fire Attack Utilizing Interior and Exterior Streams on Firefighter Safety and Occupant Survival: Water Mapping. UL Firefighter Safety Research Institute, grudzień 2017. http://dx.doi.org/10.54206/102376/nevx1787.
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As research continues into how fire department interventions affect fire dynamics in the modern fire environment; questions continue to arise on the impact and implications of interior versus exterior fire attack on both firefighter safety and occupant survivability. Previous research into various types of fire ground ventilation, flow paths, and exterior fire streams has provided the fire service with an increased understanding of fire dynamics. However, in some instances, the information from the studies may not support current, experienced-based practices. This gap between the research to date and the fire ground suppression experience has driven the need for further study. Therefore, research into the various methods of fire attack will allow a broader understanding of how firefighter interventions on the fire ground can impact the outcome of both life safety and property protection. This study will build upon the fire research conducted to date by analyzing how firefighting tactics, specifically different fire suppression tools and tactics, affect the thermal exposure and survivability of both firefighters and building occupants and affect fire behavior in structures. The purpose of this study is to improve firefighter safety, fireground tactics, and the knowledge of fire dynamics by providing the fire service with scientific information, developed from water flow and full-scale fire testing, in representative single-family homes. The project will be comprised of 3 parts: • Part I: Water Distribution • Part II: Air Entrainment • Part III: Full-Scale Residential Fire Experiments This report details the results and analysis from the water distribution experiments. These tests were conducted without the presence of fire to gain a fundamental understanding of water flows into compartments. Each test was designed to quantify water distribution within a compartment by evaluating the differences caused by various application methods, hose stream types, nozzle movements, pressures/flow rates, stream locations and elevation angles.