This study investigates the stability of a surface flame burner using a photodiode and data acquisition system. The light intensity fluctuations were measured by the photodiode and, using fast Fourier transform, they were transferred from the temporal to the frequency space. To illustrate the dynamic behavior of premixed flames, flames are divided into two regions of cellular flames and surface flames. This classification is dependent on the flow rate and the equivalence ratio. In surface flames, as the flow rate increases, the oscillation frequency also increases because the hot burned gas velocity increases. In cellular flames, as the flow rate increases, oscillation frequency decreases. At identical flow rates, the sharp decrease in the oscillation frequency indicates the appearance of cellular flames so we can find the transition from the surface flame to the cellular flame. At a constant flow rate, with an increase in the equivalence ratio, there is no increase in the oscillation frequency, the transition from the cellular flame to the surface flame occurs. The initiation of the transition from the cellular flame to the surface flame occurs at flow rates of 1. 1, 1. 2, 1. 3, 1. 4, 1. 5, 1. 6 m3/h and at equivalence ratios of 0. 6, 0. 62, 0. 62, 0. 64, 0. 66, and 0. 67, respectively. The location of the transition corresponds to the start of the liftoff zone based on the image processing. This research is innovative because it is possible to evaluate flame stability using a non-intrusive method without disturbing the flame shape and damaging the flame regime.

In this study, a fully premixed cylindrical surface flame burner is investigated in laboratory research. The burner was analyzed in heating capacities 11.74-17.14 kW and its equivalence ratio 0.4-1.6. The results are including two sections of spectroscopy and flame image analysis. In the chemiluminescence section, the maximum heat release from the perforated cylindrical burner is obtained by examining the intensity of hydroxyl radiation in the equivalence ratio of 0.8. In the second part of chemiluminescence, the equivalence ratio is estimated by using the intensity ratio and curve fitting from natural flame radiation. The color and state of the flame changed from the equivalence ratio of 1.6 to 0.44, respectively, from green to yellow and red flame, blue and lift-off flame, and eventually blow-off. The satisfactory operation that is stable blue flame without lift-off and flashback is observed in the range of 0.7-0.85. This process was performed for six thermal capacities, and its results were collected in a chart called the functional burner diagram. A satisfactory operation can be selected by a functional diagram in different burner powers.

In the present research, combustion species were investigated in perforated natural gas burner based on flame emission spectroscopy. An experimental investigation is performed on a new burner test rig which is one of the most popular burners used in condensation boilers through a spectrometer-fiber optic to get the flame emission of a perforated burner. Combustion species H2O*, OH*, CH*, C2* and CO2* are detected from their chemiluminescence The emission of CO2* which has the main role in heat release rate of burner was investigated for different equivalence ratios (Φ) and burner powers of 11-16 kW showing an intensity peak in the range of Φ between 0.78 to 0.85 that corresponds to the maximum heat release rate. Emission of OH* was also investigated being the main indicator of NO regarding its producing mechanism. Its maximum was found at the range of at Φ=0.78 to 0.85 for different burner powers. A similar experiment showed that OH*/CH* intensity ratio was independent of burner power as is confirmed by previous researchers. One could infer the equivalence ratio from the flame emission.

Background and Aims: When composite resin polymerizes, shrinkage stresses tend to produce gaps at the tooth/ restoration interfaces. Surface sealants may reduce or avoid problems related to the marginal interface. The aim of this study was to evaluate the effect of two different surface sealants (Fortify and Optiguard) on the microleakage of class V resin composite restorations.Materials and Methods: Twenty three sound noncarious molars were collected. Totally, 45 Class V cavities with the occlusal margins in enamel and cervical margins in cementum were prepared in both buccal and lingual surfaces. The specimens were randomly assigned in three groups (15 cavities in each group) and then restored with a resin composite. After the finishing and polishing procedures, the restorations in each group were covered with a specific surface sealant, except for the control samples, which were not sealed. After placing restorations, the specimens were thermocycled and then immersed in a 50% silver nitrate solution (tracer agent) for four hours, sectioned longitudinally and analyzed for leakage using a stereomicroscope in a blind manner. The marginal microleakage was evaluated at the occlusal and cervical interfaces and compared among the three groups using the Kruskall-Wallis and the Mann-Whitney U tests.Results: Microleakage was found in all groups at both occlusal and cervical margins. Significantly greater leakage was observed at the cervical margins compared to the enamel margins of the material groups (P=0.005).There was no statistically significant difference among the groups at occlusal margins (P=0.66). In the cervical region, Fortify showed improved results and statistically presented the lowest degree of microleakage (P=0.003).Conclusion: The used sealant materials presented different rates of effectiveness and Fortify decreased marginal microleakage significantly.

Nowadays, the use of resistant and high melting point thermocouples is considered as an efficient and inexpensive tool for measuring the temperature of hot gases produced by combustion. Temperature measurement by thermocouples has inherited errors due to the radiation loss and conduction loss. Therefore, it is necessary to correct this error. In this research, the thermocouple is firstly modeled using a numerical method. The validity of the original code is accredited by comparing the results with a similar previous study. Then, the effects of thermocouple diameter and average flow velocity are investigated on the thermocouple error. The error increases about 50% with increasing the thermocouple diameter from 0. 5 to 1 mm. Besides, the error decreases about 41% with increasing the average velocity from 1 to 5 m/s. Based on a previous experimental study, the thermocouple modeling results indicate that the maximum errors for thermocouples with diameter of 300 and 500 microns are 30. 8% and 39. 6% under these conditions, respectively. In the following, a novel comprehensive solution is suggested to calculate the simultaneous distribution of temperature and velocity. Its results confirm that this algorithm has acceptable accuracy for high temperature flow conditions.

Thermodynamic calculations of the combustion heat release, specific impulse, and volumetric specific impulse show that metal fuels can exceed hydrocarbon fuels in volumetric energy content and in the case of boron exceeds conventional fuels on a mass basis as well. The refractory nature of metal fuels and their combustion products also suggest that they may permit ramjets utilizing subsonic combustion to extend their operation to hypersonic Mach numbers. In this paper, formation of stabilized flame using a pure powdered metal fuel without the use of hydrocarbons is investigated experimentally. The ability to effectively inject powdered, metal into a combustor is demonstrated using a laboratory-scale dispersion apparatus. Dynamic parameters of burning time and flame speed of aluminum dust flame have been measured by dust combustion apparatus. Results imply that the burning time is decreased, while the oxygen concentration is increased.Also, the replacement of nitrogen with argon increases burning time. This is, because of the increase in aluminum dust reaction rate. The flame speed of aluminum dust is near the diffusion flame and its differences with hydrocarbon fuel flame are to stabilize the dust flame in rich mixtures.

Embryogenic calli production in Vitis is mainly possible by use of such regenerative tissues as anther and ovary. Because of long periods of time required for obtaining such tissues, use of such vegetative organs as leaf explant would be a promising alternative. Towards this end, leaf explants were taken from two varieties of ‘Flame Seedless’ and ‘Red Sultanina’ to be raised in. MS medium, consisting of 2.5 mM 2, 4-D, 1.1 mM BAP, 1 g/l Cazein Hydrolizate, 20 g/l sucrose, and 7 gr/l of agar. After two months, calli were transferred to the same medium except for 2-4, D which was replaced by NAA. Three months after explants' culture, calli were transferred to MS medium containg varied concentrations of BAP (1, 2 & 3.5 mg/l), and IAA (2, 5 & 15 mg/l). Results showed that among different hormonal treatments, the fifth medium (BAP 5 mg/l & IAA 2 mg/l) induced a maximum embryogenesis in calli of cv. Flame Seedless.

Nezami's Poem is in the front rank of poetry. He always attempted to choose the best words- fine words using beautiful words and expressions. His poetry is enriched by his power of imagination and awareness of the common knowledge and beliefs of the time. The common features of his speech includes a unique use of the words-word choice, creating new compounds, compounding- description, repetition, emphasis, transformation, omission, using Quranic verses, Islamic hadiths and Arabic compounds, expressions of astrology and medicine, adages, proverbs and idioms regularly used by ordinary people. He is a poet familiar with the language of ordinary people and their beliefs, customs and traditions. Since he rightfully attended to the spoken language and because of his particular style of speech, his works are full of street talks to the extent that this propery can be viewed as the prominent stylistic feature of his poems. He took advantage of the common sciences of the time and utilized the scientific, astrological and medical terms and also the technical meanings and themes of these sciences. His imagination and awareness of the sciences and beliefs made his poems productive. Some of the features of his poems are as follow:1- Imagery: Imagery refers to producing pictures, paintings or shows in the mind of readers /listeners using words. That is, the poet or writer should have such mastery over using words, space, meanings and their relations that makes him able to effectively use the sentences and words to create paintings, pictures or shows in the mind of readers or listener, to enable the reader to imagine a real painting or picture when he is over with his reading.2- Diction: Experts of language issues and grammar beliefs that word coining can strengthen the foundation of language. So, the first premise in creating fine text is to choose musical words appropriate for the given text and meaning. In the first step, melodic, expressive, rich words compatible with the spatial totality should be choosen. This powerful diction is one of the major reasons for the immortality of Nezami's poems.  3- Compounding: In addition to words which need to be musical and melodic, literary compound should supplement the musical quality of the text. Since compounding is one the major features of Persian language, Nezami effectively utilized his power of compounding and its one of the prominent features of his poetry.4- Description: In his poems, description of the nature is done through personifications, descriptions, similies and metaphors, and this description is indispensible feature of the theme that improves the manifestation of the heroes and events from the poetic perspective. Since His poems are full of personifications, all the manifestations of the nature simply represent characteristics, attitudes and thoughts of human beings. A plentiful supply of finest descriptions can be found in his Masnavi-e Khosro va Shirin 5- Repetition:Repetition of a morpheme, word or picture proves to be one of the main characteristics of his poems. Nezami uses a large variety of repetitions in his poems and this variety in repetition enriches his works. Reading the poems of Nezami, one can understand that the initial words determine the following morphs and words. In fact, words are chosen based on their melodic properties.Conclusion: Generally speaking, in a noble poem, imagination, melody and form should be consistent in order to reach the optimal goal. If they are not consistent with each other the poem may not be influential as well as possible. So, the music of the poem should be compatible with the imagination and the language of the poem. A successful poet attends both to the form and meaning of the poem and does not strengthen one at the expense of the other one. Nezami attends to both form and meaning.