Present study reports the effects of OPERATING CONDITIONS on the mixing of two co-axial streams. Produced mixing layers between the co-axial streams are investigated numerically in the developing regions. Closed form governing equations of the mixing layer flow are solved using Fully Implicit Numerical Scheme (FINS) and Tridiagonal Matrix Algorithm (TDMA). Calculations are made for the mean and turbulence properties, and spatial mixing deficiency (SMD). Obtained results show that increase in flow width does not correspond to increase in spatial mixing while increased level of centerline velocity, centerline concentration, mean vorticity, turbulent shear stress and turbulent kinetic energy (TKE) corresponds to increase in spatial mixing.

In this research, with the help of commercial software called AVL BOOST, the performance of the EF7 gasoline engine has been simulated numerically, and the effect of compression ratio and spark timing on power, torque, and thermal efficiency has been investigated. The error of the current modeling compared to the results of experimental tests was reported in the range of 3%. Also the simulation results showed that at high speed (5000 rpm) if the spark starts 25 degrees before the top dead point and the spark duration in the range is 55 degrees, the maximum output power is obtained from the engine, and as the spark duration increases, the ignition speed decreases and the output power decreases. Besides, with the greater advance of the ignition angle, a greater percentage of the input energy is lost as heat to the engine wall and the output power decreases. It is noteworthy that in the optimal CONDITIONS of spark timing at 5000 rpm, the thermal efficiency of about 38% can be achieved, which is increased by about 11% compared to the default spark timing mode.

This paper focuses on the dynamic modeling of quadrotor with respect to changes in OPERATING CONDITIONS. The main objective of this investigation is to provide complete governing quadrotor dynamic equations using the Euler-Lagrange method considering all aerodynamic forces which affect its motion. In previous papers, dynamical equations are never considered comprehensively. The study of quadrotor's dynamics permits to understand its physics and behavior and provides a precise model of the system. Once such a model is obtained, the control of quadrotor turns much simpler than current inaccurate models. In order to take into account, the set of forces and torques involved in quadrotor dynamics, the previous studies are used and after describing each of the forces and their precise terms, the complete dynamic quadrature model is presented. At the end, the system's performance is simulated in two different OPERATING CONDITIONS, one regardless of the external object coupled with quadrotor, and the other in the coupled condition with a camera, and by this means, the achieved dynamic model is validated. In the first OPERATING CONDITIONS in two different tests, the dynamic equations of the present work will be compared against the previous ones. In the second OPERATING CONDITIONS, the quadrotor performance under influence of a connected camera whose motion changes continuously the system dynamic equations is studied.

A method is presented to predict the onset of knock and associated performance of a spark ignition engine when primarily fuelled with gaseous fuels such as methane. It gives guidelines for choosing the best OPERATING CONDITIONS to obtain maximum power just before the onset of knock. A two-zone predictive combustion model was developed based on an estimate of the effective duration of the combustion period and the mass burning rate for any set of OPERATING CONDITIONS. The unburned end gas preignition chemical reaction activity is described by a detailed chemical reaction kinetic scheme. The variation with time of the value of a formulated dimensionless knock parameter K is calculated. This parameter relates the total energy released within the end gas due to autoignition reaction activity per unit of corresponding instantaneous volume relative to total energy release per cylinder volume that would take place normally due to regular flame propagation. When knocking is encountered, the value of K builds up to a sufficiently high value that exceeds an acceptable limit. Under normal OPERATING CONDITIONS, the value remains throughout the combustion period at comparatively low levels.

Oil coking and turbine seal ring melting are among the main failure modes of engine turbochargers. During the turbocharged internal combustion engine development process, the cooling and lubrication system must be checked for appropriateness of the desired condition for turbocharger journal bearing and seal rings which the turbocharger manufacturer defines. In this study turbine and compressor journal bearings and turbine seal ring temperature were measured at different engine speeds and loads as well as coolant flow at engine hot shutdown CONDITIONS. Also, the effect of inlet coolant temperature and exhaust gas entering the turbine housing on bearing housing temperature was investigated. The experimental test shows that maximum heat transfer from the turbocharger to the coolant is at the engine's maximum power point. Among measured points, turbine sealing always has the highest, and Compressor journal bearing has the lowest temperature. Coolant and oil temperature are the main controllers of temperatures but exhaust gas temperature has a lower effect on temperature at the investigated point.

The essential role of surge arresters is equipment protection against overvoltages to increase system reliability. Different monitoring techniques have been used to diagnose surge arrester condition. Leakage current analysis methods by the extraction resistive and capacitive components of leakage current are a conventional method for surge arrester monitoring. Insufficient appropriate thresholds are most important restriction of these kinds of methods. In this paper, the impact of pollution, ultraviolet aging and varistors fault on harmonic spectrum of leakage current have been evaluated experimentally. Real tests and examinations have been done on different metal oxide surge arresters to investigate effects of mentioned factors on leakage current harmonics. To show results performance, bees-adaptive network based fuzzy inference system has been applied.

In this paper, results obtained from investigations on a polysulfon ultrafiltration membrane fouled by precipitation of milk components have been presented. OPERATING CONDITIONS such as temperature, pressure and crossflow velocity, which could play an important role in the fouling processes, were selected for the studies. Results show that dimensionless fouling resistance increase with increasing temperature and pressure and decreases cleaning agents on recovery of the fouled membrane has also been studied. Results show that a combination of sodium dodecyl sulfate and sodium hydroxide can be used as a cleaning material to reach the optimum recovery of the polysulfon membrane used in milk concentration industries. A mixture of sodium hypocholorite and sodium hydroxide shows acceptable results, while washing with any acidic material has no considerable result.

Diehylbenzene (DEB) dehydrogenation reaction was conducted to produce divinylbenzene (DVB) and ethylvinylbenzene (EVB). The effects of temperature, catalyst weight, and time factor on the performance of the dehydrogenation reactor were investigated experimentally. Temperature varied from 550 º C to 600 º C. Temperature affects the conversion of DEB to DVB significantly. By increasing the temperature from 550 º C to 580 º C, the mole fraction of DEB at the outlet of the reactor is decreasing; however, a further increase in temperature up to 600 º C does not decrease the mole fraction of DEB at the outlet of the reactor. Catalyst weight varied from 10 g to 40 g. The results showed that the trends of EVB+DVB production and DEB consumption were identical at various catalyst weights. To obtain an optimum time factor for the DEB dehydrogenation process, experiments were conducted at various time factors. The results showed that the optimum time factor for DVB as the desired product was 825 g/h. mol. The data and information provided in this research can be used for scale-up and optimization purposes.

This work attempted to determine the optimum CONDITIONS required for the coagulation and flocculation process as an essential stage of the ceramic wastewater treatment. Coagulation and flocculation is a very necessary step in industries as it lessens turbidity, color, and odor of wastewater. The experimental work was performed in several runs. The volume of wastewater used in each run was 200 mL and was kept at this value throughout. In certain runs, the speed of the mixer was varied while keeping the quantity of coagulant and flocculant constant in order to determine the optimum speed that resulted in the least turbidity. A speed of 5% was chosen as the ideal process speed according to the results obtained. Next, experiments were operated at this optimum speed while changing the dosage of coagulant and flocculant in order to decide the optimum dosage. Coagulant and flocculent amounts of 0.4 g (without booster) and 0.2 g (with booster) selected after the readings were taken. For all the readings, a turbidity meter was used providing results in Nephelometric Turbidity Units (NTU). Lowest turbidity was achieved when using 5% speed with 0.4 grams of coagulant and 0.4 grams of flocculant, or 5% speed with 0.2 grams of coagulant, 0.2 grams of flocculant and 0.25 g/L of booster coagulant. According to factorial design analysis, such as parameters as impeller speed and dosage have an influential impact on the turbidity; while the booster has insignificant influence and other interactions between parameters are important.