INTERNATIONAL JOURNAL OF INDUSTRIAL ENGINEERING AND PRODUCTION MANAGEMENT (IJIE) (INTERNATIONAL JOURNAL OF ENGINEERING SCIENCE) (PERSIAN)
Year:2008 | Volume:19 | Issue:9 (SUPPLEMENT OF MATERIALS, MINERAL AND CIVIL ENGINERING)|Papers Count:13

Jajarm bauxite mine is the greatest bauxite deposit in Iran. A determined reserve of bauxite in this deposit is about 160 million tones. This mine is located on 16 Km of Northeast Jajarm city, in Khorasan-e-Shomali Province of Iran. The stability problems in 66 meters height of dolomite wall cause to starting slope stability on this wall. After practical classifications and using limit equilibrium software, circular slide failure is determined. In this paper, we find the critical circular sliding surface, by using genetic algorithm. The objective function for genetic algorithm is simplified bishop method. Results show that instantaneous failure is happened, if serious modification of slope doesn't apply.

Carbide ceramics such as boron carbide due to their unique properties such as low density, high refractoriness, and high strength to weight ratio have many applications in different industries. This study focuses on direct bonding of boron carbide for high temperature applications using nickel interlayer. The process variables such as bonding time, temperature, and pressure have been investigated. The microstructure of the joint area was studied using electron scanning microscope (SEM) technique. At all the bonding temperatures ranging from 1150 to 1300°C a reaction layer formed across the ceramic/metal interface. The thickness of the reaction layer increased by increasing temperature. The strength of the bonded samples was measured using shear testing method. The highest strength value obtained was about 100 MPa and belonged to the samples bonded at 1250 for 75 min bonding time. The strength of the joints decreased by increasing the bonding temperature above 1250°C. The results of this study showed that direct bonding technique along with nickel interlayer can be successfully utilized for bonding boron carbide ceramic to itself This method may be used for bonding boron carbide to metals as well.

Determination of the mechanical parameters of rock joints and mainly the influence of infill material of joints on the shear strength of discontinuous media has a great importance. For achieving this goal, till many researches have conducted on the simulated models with the use of physical modeling and laboratory testing. However, many of them are rather unemployable for some reasons such as different conditions of the surface and underground environments. Accordingly, in this paper an exact model has been developed for prediction of the shear strength of in filled rock joints using surface sampling of natural joints, numerous direct shear tests in different filling conditions and finally by utilization of the artificial neural networks. In order to increase the network accuracy, kinds of filling materials separated and a network with two hidden layers has been developed for each kind. The comparison of the results with empirical models demonstrated that these networks have better capability in prediction of the parameter in question.

This paper considers the effects of plasma nitriding parameters including screen hole size, top lid type (screen or iron plate), and the temperature as well as the composition of the treatment gas on surface properties of DIN 1.6580 low-alloy steel. Nitriding was carried out at 550 and 580oC for 5 hr in the gas mixture of (N2/H2): 3/1 and 1/3. The properties of nitrided specimens were assessed using metallographic techniques, XRD, Micro-hardness measurements, and SEM. X-ray diffraction analysis confirmed the formation of g’-Fe4N and e- Fe2-3N phases during the nitriding process. The findings show that the thickness of the compound layer increases with treatment temperature as well as nitrogen percentage in gas mixture and that an increase in screen hole size has no effect on the compound layer thickness under screen top lid condition and also that an increase in screen hole size at the same temperature results in an increase in the thickness of the compound layer under iron plate top lid condition. The results of micro-hardness measurements indicate that surface hardness increases with temperature as well as nitrogen volume in treatment gas. It was also found that hardness values obtained using screen top lid is relatively greater than those obtained using iron plate top lid.

The objective of the present study was to evaluate the mechanical properties of Al/ZrO2 composites produced via vortex technique. Al-356 alloy and ZrO2 particles with average diameter of 0.79 micron were used as the matrix and the reinforcement, respectively. The effect of ZrO2 content and casting temperature on tensile strength and fracture surfaces of the composites were studied. The results indicate that addition of ZrO2 particles into the matrix significantly increases mechanical properties of aluminum alloy. In this regard, the best tensile strength result was obtained in the specimen containing 15 vol% ZrO2 produced at 750oC which showed an increase of about 60%. The Al-356/ZrO2 composite specimens fracture in a brittle manner with little or no necking has been observed.

Many researches have been carried out in field of “Roof rock behavior in coal mines", most of them concentrated on mines development networks; but a less attention have been paid to assessment and classification of roof strata behavior over longwall coal mining panels. However various parameters influence on the deformability behavior of the stratified rock mass. This paper discusses the most effective parameters and the degree of influence of each of them on the stability behavior of coal mines roof rock. Based on the assessment, six parameters were recognized witch relevant to rock mass including uniaxial compressive strength (UCS), tensile strength, moisture sensitivity, joints, bedding thickness and orientation  and dips of discontinuities relevant to face and surface of working area. In the proposed system, the roof rock over a longwall panel is assigned a rating from 15.5 to 100, with a higher rating corresponding more stable roof. Based on this rating system, a roof maybe classified into five modes: extremely unstable, highly unstable, Medium stable, good stable, highly stable.

One of the most important factors leading to the success of a cement plant is its location. A multicriteria decision-making method is used to rank alternative plant locations. The set of criteria is established and corresponding criteria should be established for each case study, although this multicriteria decision-making approach has broader applicability. In this paper, ELECTRE approach with five criteria is used to develop a location evaluation for Alumina - cement plant in East- Azerbaijan province of Iran. Five alternatives for the plant location are evaluated. The main criteria are transportation consideration, water supply, power supply, fuel supply and land consideration. Other criteria have the same importance as for five alternatives. Finally Alternatives are ranked and the best site is proposed.

Water inflow into underground spaces is one of the serious challenges in safety management which could lead to undesirable effects on excavation process. Therefore, determination of the groundwater inflow into tunnel is necessary to design dewatering systems and predict safety arrangements. In this paper, the groundwater inflow into Kuhin railway tunnel (with 100m overburden and 55m water table from project line) was modeled by SEEP/W software (based on the finite element method) for different excavation stages. The results showed that the water inflow into the Kuhin tunnel in full excavated state is equal 2.194e-4 m/s2.

Performance of a pilot Biofiltration system in removing of Triethylamine (TEA) vapor from air stream was evaluated in this study. Experiments were conducted with a 6-L three section biofilter containing a mixture of compost (60%) and wood chips (40%). The system was operated at 30±1oC. Municipal activated sludge was added initially to promote microbial growth and the systems were started after initial adaptation period of 40 days. Various loading rates (6-114 g/m3.hr), in detention time of 48 seconds and media moisture of 50-55% were studied to evaluate the removal efficiency of biofilter. Results indicated that all the influent TEA with below concentration of 180 ppm was removed with more than 90% efficiency. In concentration of 180 ppm, more than 90% TEA was hydrolyzed to ammonia in the pH range of 8-9. About 1/3 of biodegraded nitrogen was N-NH3 (gas), 1/3 was converted to NH4+ and 1/3 was converted into nitrate and organic or cell nitrogen. Nitrogen forms were varied over time and with the height of the packing. In certain conditions of this research, the biodegradation of TEA was good but convertion of nitrogen to nitrate was not so well accepted.

To evaluate seismic vulnerability of existing reinforced concrete buildings in Iran, cyclic and monotonic load test on seven columns was carrie out. Four specimens represented semi-engineered buildings in which seismic provisions are not satisfied adequately. There other specimens represented well proportioned constructions, in accordance with provisions of intermediate ductility, AC1318-99, which is a common reference in Iran. Based on test results, hystersis curves, backbone curves, and idealized curves for two types of columns were established. The semi-engineered specimens showed 35% reduction in strength and 39% reduction in initial stuffiness and 35% loss of energy dissipation capacity in comparison to standard ones. Both types of specimens were subject to similar seismic demand, and such reduction of cyclic capacity indicated vulnerability of existing buildings and their need to be retrofitted against seismic action. The tests also showed that concrete spalling started at a drift ratio of about 2% for all specimens and it did not depend on the history of loading. All specimens showed a relatively ductile response with a little pinching in the hystersis curve, and negligible loss of intercycle and outcycle stiffiness. The standard specimens demonstrated relatively good cyclic capacity and corifirmed the provisions of intermediate ductility, AC1318-99, for columns.

Many researches have been conducted on structural high strength lightweight concrete and its material, as well as the effects of these materials on the mechanical properties of structural lightweight concrete, the present study dealt with the production of high strength lightweight concrete which satisfies the ACI codes requirements through a trial and error procedure. 480 standard cylindrical samples were prepared and tested. 12 aggregate proportions were proved to be acceptable in terms of ACI codes that justify the construction of concrete structure by such high strength lightweight materials; finally, economic evaluation was performed to investigate the feasibility of working with these materials in real world.