فهرست مطالب m. ghafoori

Successful detonation of commercial explosives due to the low sensitivity of these compounds requires the use of sensitizing agents in the formulation. The sensitizer improves the initiation, velocity of detonation and performance of the explosive by improving the propagation of the shock wave caused by the detonation reaction. The type of sensitizer used in commercial explosives is one of the important factors in determining the cost of production as well as the safety, performance, shelf-life and application characteristics of commercial explosives. In this paper, various sensitizing agents that are currently used, including aluminum powder, monomethyl ammonium nitrate, chemical gassing, microballoons and porous ammonium nitrate prills, have been investigated. In the past, molecular explosives such as nitrocellulose and TNT were used to sensitize commercial explosives. In order to reduce the problems and risks of production, transportation and use, self-explosive materials were gradually replaced by new methods. The use of aluminum powder or organic nitrate amines in combination with micrometer air bubble sources such as microballoons, chemical gassing and porous materials completely release the high-energy capacity of commercial explosives along with increasing performance, adjusting production costs and increasing efficiency of blasting operations. Styrofoam, perlite and some other porous materials have also been tested but are not operational due to some problems. Optimal sensitizing agents maintain the advantage of relatively low sensitivity of commercial explosives and at the same time the desired initiation of these compounds by using suitable primers in blasting operation. Thus, the need for higher hazard class compounds for initiation of commercial explosives is eliminated and the cost of production is reduced.

In this article, the history, different types applications, literature and common terms in the field of civil explosives and some special tests of this type of explosives and finally the hazards of working with these products have been studied. Modern commercial or civil explosives based on ammonium nitrate were developed during the 1950s. These products are widely used in mining, road construction, tunneling and other construction activities and play a major role in the economic growth of countries. Slurries, water-gels, emulsions, dynamites and ANFO are the currently being produced and consumed civil explosives. Special terms in the field of production, characterization, classification and consumption of civil explosives are common, including permissibility, water resistance, COD, pressure desensitization, incendivity, etc. The sensitivity and safety of civil explosives is different from that of military explosives. For this reason, accidents related to civil explosives are mainly due to the user's unfamiliarity with the properties of these compounds. The field of production and work with civil explosives requires a chemistry and engineering vision in order to research and develop these useful products without incident

The aim of this study was to determine the air quality index (AQI) and to investigate its relationship with meteorological parameters in Mashhad for 2014. In this study, moment concentrations of air pollutants in Mashhad for 2014 were prepared and the amount of AQI was calculated and air quality was determined. Then, data analysis was performed using Kruskal-Wallis and Mann-Whitney tests at a significant level of 5% in SPSSV.23 software. Finally, data related to meteorological parameters were prepared during 2014 and ARIMA time series model and R software (3.3.0) were used to investigate its relationship with air index pollutants in non-delayed and one day late modes. The results showed that air quality of Mashhad was in a very bad condition in terms of maintaining the health of community members, especially sensitive groups, as the concentration of pollutants in this city was higher than Iranian standard (100) in 245 days of the study period. The PM2.5 was the most important pollutant during the study. It was also found that among the climatic parameters, temperature and pressure have the greatest direct effect on the concentration of air pollutants. Moreover, results showed the immediate effect of temperature on the concentration of air pollutants, although other atmospheric elements are able to significantly affect the outcome over time and with a time delay (one day in this study). The results indicated that quality of model computation depends on changes in atmospheric parameters, so that a quantitative measurement for each pollutant can be achieved based on meteorological data.

Brittleness is one of the most important mechanical properties of rock which has a widespread application in underground constructs drilling like tunnel drilling. Although many method have been introduced for estimating brittleness, no standard has been mentioned for measuring brittleness. In this research, experiments for determining   brittleness of S20 along with petrographic (main mineral percentage), physical (dry density, saturation density, porosity and water absorption percentage), mechanical (uniaxial compressive strength, Brazilian tensile strength , point load test) and dynamic properties (pressure and shear wave velocity) in the two states of dry and saturated were performed on 19 test samples of igneous rocks (granite, granodiorite and dacite) selected from Sangan iron ore mine in khaf. Statistical analysis of the results shows that brittleness of samples increases with increasing alkali feldspar and quartz and also reducing plagioclase. Also existence of micro particles and carbonate veins decreases strength and increases the brittleness of rock and facilitate excavatability of samples which is more prominent in saturated state. There is an inverse relationship between S20 brittleness and the brittleness indices, and as the value of S20   brittleness increases, the value of brittleness indices decrease. The relationship between S20 brittleness and brittleness indices B3 and B4 has the highest coefficient of determination. As a result, it can be said that the brittleness measured in the laboratory can be more realistic in expressing the brittleness of rocks.

Polybutadiene acrylic acid acrylonitrile (PBAN) is binder for composite solid propellants used in spacecraft systems, curing kinetics of which is very important. In this research, the effect of functionality of epoxy curative on the curing kinetics of PBAN is researched. Equivalent stoichiometric ratios of PBAN and di-functional (DER 331) and tri-functional (LY 5052) epoxy curatives was cured at 80ºC. During curing reaction, 16 in-situ FT-IR spectra were obtained from the samples to monitor the progress of ester group formation (curing progress). Curing reaction of PBAN with both curatives consists of two separated steps with dissimilar kinetics. Transition from first step to second step of curing reaction, for difunctional curative is occurred after 7 days while, for tri-functional curative after 3 days. The rate of curing reaction using di-functional epoxy curative, is approximately half of tri-functional epoxy curative. These results are important in the aspect of production process and mechanical properties of final product.

In EPB-TBM tunneling, a positive face control during tunnel excavation is delivered and the tunnel face is supported by pressure from the mass of remolded soil within the cutterhead chamber. EPB TBMs operate more eectively when the soil immediately ahead of the cutterhead and in the chamber forms a plastic plug, which ensures face support. The target properties for extracting soil in an EPB TBM can best be described as a soil matrix exhibiting a soft workable plastic consistency. The behavior of excavated soil from mixing up to extraction depends mainly on the property called workability of conditioned soil. Workability in simple terms can be de- ned as the ease with which the excavated soil can be mixed with additives, compressed in pressure chamber, owed freely from the face and finally extracted from screw conveyor. Furthermore, the workability is an indicator for the plasticity of the support media, comparable to the consistency of cohesive grounds and thus a criterion for the applicability of EPB tunneling. The factors which effect the workability of conditioned soil are water content, fine grain, foam injection ratio (FIR). In this study, effecting 10 and 20 percentage of water content and FIR on workability of conditioned soil for EPBTBM tunneling is assessed with laboratory slump test. The 66 laboratory trials of soil-foam-mixtures were made to investigate the in uence of the mentioned parameters on workability of conditioned soil. To analyze the available data using statistical methods, relationships between mentioned parameters and slump test results were investigated. Results of analyzes show that there are a quantitative relation between water content and the workability for the application of EPB shields. The present study clearly showed that the decrease of water content and FIR became stronger with the decrease of the slump of conditioned soil. Finally, in this study, a new empirical chart, for assessment of and workability of conditioned soil is suggested.

Land subsidence due to excessive extraction of groundwater has been reported in different parts of the world and several plains and Iran. Mashhad Plain during the past 40 years has been faced with 60 m drawdown of water table. This drawdown caused land subsidence in some areas of the plain. Land subsidence effects appear as rupture and curvature of well casings and they cause destruction of subsurface structures in wells. Based on data available from three GPS stations in Mashhad plain، and with respect to geological parameters of the study area، effective factors on rupture of well casings which account for abundant damages every year، have been investigated in this paper for Toos area، northwest of Mashhad City. A deep grain size profile of underground layers has been provided for problematic area in the study area. Also، soil grain size profile in two levels، above and below the groundwater surface، has been provided using ArcGIS software for investigation of current situation and anticipation of continuity conditions of land subsidence and therefore its resulted destruction in the future.

Blepharitis or of the eyelids is a common disease of eye which may be seborrheic or bacterial. Often blepharitis is asymptomatic but maybe associated with some signs and syrnptoms such as itchy eyelid skin and redness ofeyelid margine. Blepharitis can anterior orposterior or mixed. Posterior Blepharitis is meibomain glands dysfunction and anterior Blepharitis can be seborrheic or staphylococcal. We have studied 100 blepharitis cases who came to the ophthalmology department of22-Bahman hospital. The average age was 36.92+ 22.2 years old and 60% were female and 40% were male. 44% of these cases were housekeeper and 22% student most ofthe patients (86%) hadn´ t been treated before and family history was negative in 94% our patient had biepharitis for meanly 4.19 monthes. Seborrheic blepharitis was seen in 46% and staphylococal blepharitis in 28.50% and mix blepharitis was seen in 15.5% Themost common signs and synptons associated with blepharitis include itchy eye skin eyelid rnargin redness, mebomian glnnds inflarntion (66%, 38%, 34% respectively) irritation and foreign body sensation, eyelid - margin irregularity and congunctival hyperermia are also common in blepharitis. Oily discharge, fibrin clot, whitening of eyelashes, chalasion and hordelum.Thin and small eyelashes, punctate or marginal keratitis, ring ulcer and xerophthalmia are rare. All af the blepharitis manifestations are often bilateral and right eye involverent is more common in unitaral types. The most common cause of blepharitis is seborrheic type and staphylococal is the next.