Luminous Zone Research Articles

Research on Tunnel Interior Zone Luminance Evaluation Method and its Application

Because of the special traffic environment, the tunnel is called a bottleneck on the highway sections; there is a huge risk of safe operation. Tunnel interior zone lighting plays an important role in the tunnel; good lighting can eliminate depression and driving fatigue of the driver in the tunnel. In this paper, freeway tunnel interior zone lighting is as the research object. We analyzed the driver's demand for freeway tunnel interior zone lighting and transformed illumination to luminance in the model of driver workload, operating speed and the illumination. And this model is established by our group. According to comfortable and relatively comfortable driving workload intense threshold, we can get the safe and comfortable luminance threshold of tunnel interior zone. This paper proposed a detection and evaluation method in freeway tunnel interior zone luminance, and the method have been applied and verified on one freeway in south China.

Effects of particle size distributions on flame propagation mechanism during octadecanol dust explosions

To reveal the effects of particle size distributions on flame propagation mechanism during octadecanol dust explosions clearly, the flame propagation through dust clouds with three different particle size distributions in an open space were recorded using an approach combined by high-speed photography and band-pass filter. From the direct light emission photographs and CH emission photographs, it has been demonstrated in the experiments that the flame front structures were changed as varying the particle size distributions. Flame propagated in the dust cloud with a smaller particle size was characterized by a regular shape and spatially continuous combustion zone structure, which was similar to the premixed gas explosions. On the contrary, when flame propagated through the dust cloud with a larger particle size, discrete blue luminous spots appeared surrounding the yellow luminous zone. Further increase in diameter resulted mostly in the appearance of blue spot flames and the disappearance of yellow luminous zone in the flame propagation process. Additionally, a simple mathematical model was developed to determine the critical particle size to illustrate the different flame propagation mechanisms in octadecanol dust explosions.

Agglomeration Characteristics of Aluminum Particles in AP/AN Composite Propellants

AbstractMost solid rockets are powered by ammonium perchlorate (AP) composite propellant including aluminum particles. As aluminized composite propellant burns, aluminum particles agglomerate as large as above 100 μm diameter on the burning surface, which in turn affects propellant combustion characteristics. The development of composite propellants has a long history. Many studies of aluminum particle combustion have been conducted. Optical observations indicate that aluminum particles form agglomerates on the burning surface of aluminized composite propellant. They ignite on leaving the burning surface. Because the temperature gradient in the reaction zone near a burning surface influences the burning rate of a composite propellant, details of aluminum particle agglomeration, agglomerate ignition, and their effects on the temperature gradient must be investigated. In our previous studies, we measured the aluminum particle agglomerate diameter by optical observation and collecting particles. We observed particles on the burning surface, the reaction zone, and the luminous flame zone of an ammonium perchlorate (AP)/ammonium nitrate (AN) composite propellant. We confirmed that agglomeration occurred in the reaction zone and that the agglomerate diameter decreased with increasing the burning rate. In this study, observing aluminum particles in the reaction zone near the burning surface, we investigated the relation between the agglomerates and the burning rate. A decreased burning rate and increased added amount of aluminum particles caused a larger agglomerate diameter. Defining the extent of the distributed aluminum particles before they agglomerate as an agglomerate range, we found that the agglomerate range was constant irrespective of the added amount of aluminum particles. Furthermore, the agglomerate diameter was ascertained from the density of the added amount of aluminum particles in the agglomerate range. We concluded from the heat balance around the burning surface that the product of the agglomerate range and the burning rate was nearly constant irrespective of the added amount of aluminum particles. Moreover, the reduced burning rate increased the agglomerate range.

Automatic inspection system of LED chip using two-stages back-propagation neural network

This study proposed an automatic LED defect detection system to investigate the defects of LED chips. Such defects include fragment chips, scratch marks and remained gold on the pad area, scratch marks on the luminous zone, and missing luminous zone respectively. The system was based on positioning and image acquisition, appearance feature recognition, and defect classification. The normalized correlation coefficient method was used to locate the chip and acquire its image, the K-means clustering method was used to distinguish the appearance, pad area, and luminous zone of chips. In terms of pad area detection, histogram equalization was used to enhance the pad image contrast, and statistical threshold selection and morphological closing were applied to modify the impure points in the pad. Feature values of the pad area were then calculated. The optimal statistical threshold separated the luminous zone and background from the substrate. After processed with closing operation, features of the luminous zone were extracted. Finally, features of each part were clarified by an efficient two-step back-propagation neural network, where a designed appearance classifier and an internal structure classifier were used for recognition. From experiments, total recognition rate of this study achieved 97.83 %, proving that the detection method proposed by this study can efficiently detect LED chip defects.

Combustion Chemistry and Decomposition Kinetics of Forest Fuels

A brief review is given of the studies in combustion chemistry and decomposition kinetics of forest fuels (FF). The methods used in the study to investigate the FF pyrolysis kinetics and the combustion of the Siberian forests are described. The experiments on FF pyrolysis were conducted at high heating rates (150K/s) in a flow reactor by the method of differential mass-spectrometric thermal analysis (DMSTA) in situ using probe molecular-beam mass spectrometry, and at low heating rates (0.17K/s) by the thermogravimetric method. The kinetic parameters of Siberian FF pyrolysis have been determined for oxidative and inert media and simulation of FF pyrolysis has been conducted using the multi-component devolatilization mechanism. The flame structure of a pine branch has been studied by probe molecular-beam mass spectrometry. Species have been identified in the dark and luminous flame zones; the width of the flame zone has been measured.

Design of LED fish lighting attractors using horizontal/vertical LIDC mapping method

This study employs a sub-module concept to develop high-brightness light-emitting diode (HB-LED) fishing light arrays to replace traditional fishing light attractors. The horizontal/vertical (H/V) plane light intensity distribution curve (LIDC) of a LED light source are mapped to assist in the design of a non-axisymmetric lens with a fish-attracting light pattern that illuminates sufficiently large areas and alternates between bright and dark. These LED fishing light attractors are capable of attracting schools of fish toward the perimeter of the luminous zone surrounding fishing boats. Three CT2 boats (10 to 20 ton capacity) were recruited to conduct a field test for 1 y on the sea off the southwestern coast of Taiwan. Field tests show that HB-LED fishing light array installed 5 m above the boat deck illuminated a sea surface of 5 × 12 m and achieved an illuminance of 2000 lx. The test results show that the HB-LED fishing light arrays increased the mean catch of the three boats by 5% to 27%. In addition, the experimental boats consumed 15% to 17% less fuel than their counterparts.

The Complex Intratumoral Heterogeneity of Colon Cancer Highlighted by Laser Microdissection

To evaluate the utility of laser microdissection in the comparison of phenotypes and genetic alterations between colon cancer and corresponding liver metastasis in the context of intratumoral heterogeneity. Immunohistochemistry was performed on a series of 11 patients surgically treated for colon adenocarcinoma with liver metastases, using antibodies directed against six mucins. Immunohistochemistry was completed by laser microdissection of tumor zones with particular phenotype, luminal zone and invasion front of colon tumors. Microdissected samples were compared on the basis of microsatellite instability and alterations of CTNNB1, KRAS, and TP53. Our study demonstrated varying mucin expression within tumors, suggesting the existence of phenotypic intratumoral heterogeneity. A common immunohistochemical profile was observed in individual tumors between tumoral subpopulations and corresponding metastases. Nevertheless, the phenotypic characteristics were distinct from one patient to another. Laser microdissection underlined that phenotypic heterogeneity could rely on genotypic heterogeneity, and that some genetic alterations were common to microdissected samples from primary colon tumors and liver metastases. We illustrated intratumoral heterogeneity of colon cancer using laser microdissection, in combination with immunohistochemical and genotypic tools. This intratumoral heterogeneity could represent a major issue in the search of prognostic biomarkers.

CO 2 effects on near field aerodynamic phenomena in 40 kW, co-axial, oxy-coal, turbulent diffusion flames

The effects of oxy-coal combustion on the near-field aerodynamics of simple, co-axial turbulent diffusion flames have been investigated. Experiments were carried out in a specially designed 40 kW (100 kW nominally) combustion test rig. Results from two sets of experiments are presented, with each set using once-through CO 2, without H 2O, plus added O 2 for the oxidant stream. The first set consists of screening experiments that revealed: (i) how replacement of dilution N 2 by CO 2 (as in oxy-coal combustion) affected NO x emissions at equivalent adiabatic flame temperatures; (ii) how, for oxy-coal combustion at constant P O 2 , primary , changes in P O 2 , secondary affected lengths of both the standoff distance and the luminous zone, and (iii) how the luminosity of oxygen-enriched air flames compared to that of aerodynamically similar oxy-coal flames at similar adiabatic fame temperatures. These screening experiments also allowed for the evolution of a methodology for quantifying flame standoff distance from video images. This methodology involved photo-image processing and probability density functions (PDFs) that represented observed fluctuations in the near-field aerodynamic region. The second set consists of final experiments after the data processing techniques had been refined. Results presented here focus on the relationship between the flame shapes, as seen by an observer, to the PDFs used to quantify the fluctuating flame standoff distance. The latter was taken to be an essential characteristic of the near-field aerodynamics of oxy-coal flames. Flame images (yielding practical, but qualitative information) and the concomitant PDFs (yielding fundamental, and quantitative data) are presented showing the separate effects of primary P O 2 , secondary P O 2 , transport diluent composition, furnace wall temperature, and secondary stream preheat temperature. A simple model in which ignition was controlled by the rate of molecular diffusion of O 2 through a gas film composed of the primary jet transporting fluid appeared to correlate some of the data. These experimental data provide not only a quantitative insight into mechanisms of ignition of coal in turbulent oxy-coal flames of practical relevance, but also (with uncertainty quantification) a quantitative basis for validation of future detailed simulations of this process.

Study of Luminous Emission from a Coaxial Plasma Discharge Device in the Presence of External Transverse Magnetic Field

The experimental investigations in this paper are focused on the study of luminous radiation emission from coaxial plasma discharge device and the effect of applied transverse magnetic field Btr on it. The experiment was done in (1.5 KJ - 10 KV) coaxial plasma discharge device. The discharge is operated in Nitrogen gas at pressures from 1 to 2.2 torr. Helmholtz magnetic coils are placed outside the coaxial electrodes with its axis at a distance = 3 cm from the coaxial electrodes muzzle, then Btr with a maximum induction ≈ 0.85 T is applied perpendicularly to the expanded plasma from the coaxial electrodes muzzle. The diagnostics used in the measurements include a Rogowsky coil and a photomultiplier tube equipped with light collimator. The experimental results showed that the maximum intensity of luminous radiation is detected at axial distance (side view) z = 8 cm and gas pressure, P = 2.2 torr. It also showed that the maximum value of axial luminous plasma zone velocity = 2.383 × 106 cm/s at z = 11 cm and P = 1.4 torr. In mode of presence of external Btr, the investigations have shown that, at P = 1.4 torr the maximum intensity of luminous radiation (detected at end-view position) is reduced by 17%, the full width at half maximum, FWHM of luminous radiation signal is increased by 40 times, while the luminous radiation signal is delayed by ta = 438 µs. In two modes of operation ta and FWHM have approximately a minimum values at P = 1.4 torr.

Investigation of the temperature and species distributions in co-flow methaneâ oxygen laminar diffusion flames

Investigation of the structure of co-flow methane?oxygen diffusion flame is presented. A numerical model with a 43-steps chemical kinetics mechanism and an optically thin radiation sub-model is employed in simulations. Through simple co-flow diffusion flame experimental arrangement, visible flame extents have been measured. The methane oxygen flames have four distinct visible regions; a dark inner zone, a reddish zone, a highly luminous zone and a blue or bluish-white zone. The variation of the extents of these zones with increasing oxygen flow rate is discussed. The effect of oxygen flow rate on the species and temperature distribution is studied in detail.

Stabilized three-stage oxidation of gaseous n-heptane/air mixture in a micro flow reactor with a controlled temperature profile

Ignition and combustion characteristics of a stoichiometric gaseous n-heptane/air mixture were investigated using a micro flow reactor with a controlled temperature profile which smoothly ramped from room temperature to ignition temperature. At atmospheric pressure condition, normal stable flames in high mixture flow velocity region, unstable flames with repetitive extinction and ignition (FREI) in intermediate velocity region, and stable weak flames in low velocity region were experimentally observed. Especially at low velocity condition, distinct two luminous weak flames and one broaden luminous zone were observed. Gas sampling and analysis were conducted to interpret this phenomenon and it was supposed that those luminous flames consist of three-stage oxidation process. Computational results also showed that there are co-existing three heat-release-rate peaks in the flow direction at low velocity condition, which qualitatively supported the experimental observations. From the concentration profiles of the species, these three reactions are confirmed so-called cool, blue and hot flames, respectively. In addition, the effect of pressure on the three-stage oxidation process was examined by conducting experiments and computations at high pressure conditions. With an increase of pressure, the first and second weak flames were intensified and the third flame was weakened. Moreover, the position of the first and second weak flames shifted to low temperature side with the increase of pressure. Consequently, the first and second flames in the three-stage oxidation process become more significant at higher pressure conditions.

Functional physiology of lantern shark (Etmopterus spinax) luminescent pattern: differential hormonal regulation of luminous zones

Lantern sharks are small deep-sea sharks that harbour complex species-specific luminescent photophore patterns. The luminescent pattern of one of these sharks, Etmopterus spinax, is made up of nine luminous zones. Previous experiments revealed that in the largest of these zones (ventral zone), photophores are under hormonal control, light being triggered by both melatonin (MT) and prolactin (PRL). In this study, we analysed the luminescent responses to MT and PRL in five other luminous zones from 12 female and eight male E. spinax specimens. The results showed that all luminous zones respond to both hormones, with each zone having its own kinetic parameters (maximum light intensity, L(max); total light emitted, L(tot); time from stimulation to L(max), TL(max)), which confirms the multifunctional character of this shark's luminescence. L(tot) and L(max) were found to be directly dependent on the photophore density (P(D)) of the luminous zone, while TL(max) varied independently from P(D). In addition, we demonstrate a sexual dimorphism in the luminescent response to PRL, with male specimens having smaller L(tot) and TL(max) in the luminous zones from the pelvic region. As this region also harbours the sexual organs of this species, this strongly suggests a role for the luminescence from these zones in reproduction.

Filtration combustion of carbon in a non-one-dimensional solid flow

The filtration combustion of a mixture of charcoal with an inert component in a tilted rotating reactor has been studied. The effects of the tilt and rotation rate of the reactor on the width of the luminous zone were studied experimentally. The width of the luminous zone depends not only on the reaction rate and heat and mass exchange, but also on the motion of the solid.

Soot formation and temperature structure in small methane–oxygen diffusion flames at subcritical and supercritical pressures

An experimental study was conducted to examine the characteristics of laminar methane–oxygen diffusion flames up to 100 atmospheres. The influence of pressure on soot formation and on the structure of the temperature field was investigated over the pressure range of 10–90 atmospheres in a high-pressure combustion chamber using a non-intrusive, line-of-sight spectral soot emission diagnostic technique. Two distinct zones characterized the appearance of a methane and pure oxygen diffusion flame: an inner luminous zone similar to the methane–air diffusion flames, and an outer diffusion flame zone which is mostly blue. The flame height, marked by the visible soot radiation emission, was reduced by over 50% over the pressure range of 10–100 atmospheres. Between 10 and 40 atmospheres, the soot levels increased with increasing pressure; however, above 40 atmospheres the soot concentrations decreased with increasing pressure.

Ontogeny of photophore pattern in the velvet belly lantern shark, Etmopterus spinax

Bioluminescence is known to be of great ecological importance to a luminous organism but extremely few studies investigate the ontogeny of luminous capabilities. The photogenic pattern of the velvet belly lantern shark Etmopterus spinax was investigated over ontogeny (14.0–52.5 cm total length) to determine the scaling of the surface area and the photophore density of different luminous zones as well as the ecological consequences of ontogenetic variations in bioluminescence efficiency. According to the luminous zone considered, different scaling patterns were found for the surface areas while the photophore densities of all zones scale with negative allometry, even though photophore insertion occurs. No sexual differences in these relationships were found. Luminous zones can be placed in two morphologically different groups: the “coverage” and the “isolated” zones. While counter-illumination is certainly the function of the former, the latter are probably involved in intraspecific behaviours. Due to the discrepancy between luminous capabilities of these two luminous zone categories, there is an ontogenetic increase in the luminescence heterogeneity of the luminous pattern as it was shown by luminescence modelling and confirmed by direct observations of spontaneous luminescence in living sharks. This heterogeneity certainly represents a trade-off between an efficient ventral camouflage and a strong identification tool for intraspecific behaviours such as coordinate hunting, which would be particularly useful when E. spinax become fish eaters (>19 cm total length), and for sexual recognition in mature individuals.

Video-chromatic measurements of temperature fields during combustion of low-temperature solid propellants

A method for measuring temperature fields in luminous zones of burning nonmetal condensed substances (sooty flames) was implemented in the form of an automated information-measuring system which provides computer processing of digital video images with separation of the video signal into monochromatic components. The system was used to study the combustion of a low-temperature solid-propellant composition with a coolant. The statistical parameters of the temperature fields were estimated by stochastic modeling of video-recorded information, providing a better insight into the hotspot-pulsating combustion mechanism of such compositions.

Analytical Model for Determining Thermal Radiance of Fire Plumes with Implication to Wildland Fire

The present work aims at developing an analytical model for evaluating the thermal radiation of a fire plume formed by burning wildland fuels at a given burning intensity and crosswind. By resolving the equations governing gas continuity, momentum, and energy conservation for a convective (buoyancy) plume, gas velocity and temperature profile along the central line of the plume were determined, which enables a quantification of radiation intensity of flame and buoyancy plume zones. Model features are examined, and the predicted results are compared with the available experimental data. It is found that for a fire with burning intensity exceeding 600 kW m−1, the radiant heat emittable from its plume is not only contributed by the luminous flame zone but also by the buoyancy plume significantly. This indicates, for the first time, a necessity of inclusion of the contribution of the buoyancy plume in evaluating thermal impact of a fire plume on a receiver in the environment. The current work provides an important basis for convenient but reliable assessment of the fire risk of buildings raised by the occurrence of a wildland fire in adjacent areas.

Development and analysis of a LTCC micro stagnation-point flow combustor

A micro stagnation-point flow burner was fabricated using low-temperature co-fired ceramic (LTCC) tapes. Methane/oxygen counterflow micro diffusion flames with luminous zones of less than 1 mm in length and 250 µm in width were stabilized in the reaction channel of the burner and analyzed using microscopic imaging spectroscopy. The burner was built with 25 layers of LTCC tapes which were pre-laminated into seven blocks. Integrated sapphire windows and sub-millimeter sized internal channels provide optical accessibility and reactant feeds, respectively. Spatial distributions of CH* and C*2 species were measured and compared with those obtained from multi-dimensional reacting flow calculations. Results show that the location and size of the diffusion flame may be controlled by flow velocity, or strain rate, just as in larger centimeter scale flames, and that the chemical structure of the micro flames was in agreement with those predicted by the numerical simulations. In this paper, we show that LTCC tape technology may be used to fabricate microburners for continuous flow steady-state homogeneous gaseous combustion and that integrated optical windows may be incorporated into the fabrication process for in situ optical diagnostics. The understanding and analysis of the present reacting flowfield, because of its simplicity, is important to the development of more complicated microreactors and microburners, in which mixing and variable strain rates exist.

Early development of bioluminescence suggests camouflage by counter‐illumination in the velvet belly lantern shark Etmopterus spinax (Squaloidea: Etmopteridae)

The development of luminous structures and the acquisition of luminescence competence during the ontogeny of the velvet belly lantern shark Etmopterus spinax, a deep‐sea squalid species, were investigated. The sequential appearance of nine different luminous zones during shark embryogenesis were established, and a new terminology for them given. These zones form the complex luminous pattern observed in free‐swimming animals. The organogenesis of photophores (photogenic organs) from the different luminous zones was followed, and photophore maturation was marked by the appearance of green fluorescent vesicles inside the photocytes (photogenic cells). Peroxide‐induced light emissions as well as spontaneous luminescence analysis indicated that the ability of E. spinax to produce light was linked to the presence of these fluorescent vesicles and occured prior to birth. The size of photogenic organs, as well as the percentage of ventral body surface area occupied by the luminous pattern and covered by photophores increased sharply during embryogenesis but remained relatively stable in free‐swimming animals. All these results strongly suggest camouflage by counter‐illumination in juvenile E. spinax.

Burning of magnesium particles under zero-gravity and convective blow conditions

The combustion of Mg particles 400 and 600 μm in diameter in O2-N2, O2-Ar, and CO2 media at 0.5–4.0 MPa under zero-gravity and free-fall conditions were experimental studied. The burning time, light emission flux from the luminous zone, temperature and size of the zone, modes of combustion, and dispersity and character of the condensed products were determined. The burning time laws were obtained, and the main physical regularities of the combustion of magnesium particle were established.