INTERNATIONAL JOURNAL OF INDUSTRIAL ENGINEERING AND PRODUCTION MANAGEMENT (IJIE) (INTERNATIONAL JOURNAL OF ENGINEERING SCIENCE) (PERSIAN)
Year:2001 | Volume:11 | Issue:6|Papers Count:15

Dynamics of a 400 m3 industrial scale UASB bioreactor during the period of the start-up, 80% of the bioreactor was filled by a two-year old anaerobic sludge with a concentration of 40 g/L and strong methanogenic activity while the rest was filled by a wastewater having a COD value of 1000 mg/I. Two loads of 0.7 and 1.5 kg COD/m3-d at upflow speeds of 0.56 and 0.77 m/h and feed to microorganism (F/M) ratios of 0.1 and 0.19 kg COD/kg VSS-d were fed to the system. Concentration of the feed fluctuated between 1000 and 1200 mg COD/L. Due to strong methanogenic activity, a serious sludge wash-out up to 60% was observed at the begining. Moreover, because of the low ambient temperature at cold season,. the temperature of the bioreactor fell from 21oc to 10oc degrees centigrade, thereby, a heating system was found to be necessary.Despite the encountered problems, sludge seperation was achieved properly and at the lower part of the vessel, a relatively thick sludge was developed. At that condition, treatment of a feed with a pH value of 6 was carried out easily and a 60% reduction of COD was achieved. A four-day interruption in the operation due to technical failures caused a sludge compression near the bottom of the reactor and made a serious drawback on the bioreactor performance.

In this paper, an analytical approach to the crack detection of rectangular plates under external loads by vibration analysis is established. The damage is considered as an all over part through crack parallel to one edge of the plate. Avoiding nonlinearities, it is assumed that in all cases crack is open. In addition it is assumed that the plate is simply supported at two parallel sides, and it has arbitrary boundary conditions at the other edges. The presence of an aU over part-through crack on the plate introduces considerable local flexibility at the crack. This flexibility is modeled by the stress-intensity factor and compliance. The study of the influence of the effective parameters including location and depth of an all over crack, type of the boundary conditions, magnitude of the external loads, dimensions of the plate and its mechanical characteristics, on the natural frequencies of the cracked plate is the first step for establishing the damage detection method by vibration analysis. Vibration analysis of the cracked plate with an all over part-crack results in an eigenvalue problem. The solution method is established and carried out. The results of the method are presented by appropriate charts.

The three dimensional model of metal flow in the mould has been investigated using an electrical device. The results show that the flow pattern can not be repeated in a levelled mould. The flow pattern is highly affected dy the mould angel. This, results in an accurate prevention of metal flow in the mould.

Electrical machine design involves solution of a number of non-linear equations. Due to the complexities of the problem, designers' experience still plays an important role in the design process.In this paper, three-phase induction motor design is considered as a non-linear system in which the input vector, consists of specifications and required performance. The output vector, on the other hand, includes physical properties and geometrical dimensions. Neural network is then used to simulate the non-linear system, describing the motor design problem. The proposed method enables the designer to design the motor without a knowledge of the relationships governing motor design. The proposed model is trained using data provided by a manufacturer and the results are compared with those obtained by conventional methods.

Injection mould design is a complex task which consisits of different fields of knowledge such as solid modelling, polymer science and flow and solid mechanics.Therefore a comprehensive and efficient system of computer aided mould design, is still somehow far from reality. In this paper, an' attempt is made to determine the parting surfaces in injection moulds by the use of "CAD" and "IGES"; a standard tool for graphics data exchange Besides a flowchart is developed to show a typical procedure for finding the set of definition points on the parting line of parts. Determining the parting lines and surfaces are the most critical elements in injection mould design which have the most profound effects on the mould design and subsequent operation.

The joining of inexpensive steel such as mild steel to high carbon tool steel is economically advantageous, in the production of long drills and taps. Therefore, the main objective of this research is to evaluate the possibility of friction welding between the AISI D3 Cold Work high carbon tool steel and the AISl1015 mild steel. The effects of axial pressure and rotational speed on the hardness and other mechanical properties are studied. The microstructures of the weld zone and HAZ are examined by scanning electron microscope equipped with EDS analyser. The results show that if the welding parameters are optimized, there will be large improvement in the mechanical properties of the friction welded zone, i.e. the strength of the interface and the HAZ is higher than the strength of mild steel. Hence, the results of the tensil and torsion tests of welded samples show that fracture occurs in the mild steel region.

In this paper an efficient method is presented for measuring and selecting the learning rate and the learning momentum of artificial neural networks when these nets are trained for the analysis and design of regular space frames. Producing three dimensional diagrams, the learning rates and learning momentums are selected.

The stress distribution within a finite width hybrid composite lamina due to internal cracks is first studied. The results which are based on shear-lag model show that the edge cracks increase the stress concentration within the intact filaments considerably. To include the effect of matrix extension on stress distribution, a plastic zone of dugdale type is considered at the crack tip. The results indicate that with an increase in matrix stiffness, the stress concentration at the crack tip is reduced to a large extent and stress is re-distributed within the lamina in a more favorable manner.

Most of the dairy industries in Iran discharge their wastewater to the municipal sewer system. Insufficient knowledge about the organic load coming from this industry has resulted in inadequate design and organic overloading in the municipal wastewater treatment plants of this category. The objective of this project was to estimate COD, BOD, and SS reduction of whey by using chemical coagulant and natural polymers. The experiments were accomplished in two stages: At first, dit1"erenl parameters of whey are measured. In this part COD, BOD5, TS and SS of whey were estimated to be 73000, 42000, 65000, and 1200mg/lit respectively, and BOD5/COD is considered to be approximately 0.6.1. In the second phase that was the main part of the experiments, the effect of different coagulants and natural polymers on the reduction of COD and SS of whey were tested. The results indicated that maximum removal efficiency of 20%-30% in total COD and more than 90% of SS were achieved depending on coagulant used. Hence chemical coagulation could be used as pretreatment of whey and for complete treatment, another methods may be used.

Robot manipulators have the inherent characteristics of being highly nonlinear and strongly coupled. This paper represents the prime ingredients to establish reliable design tools. Through these design tools a robot designer can easily predict and foresee the impact of chanaging the operational conditions, (e.g. velocity) on the performance characteristics of a robotic manipulator. In this work, a computer plot package was especially developed and used to display the extensive analysis information in a compact form. This helps a robot's designer develop an intuitive feel for his problem and reinforces this by a visual display. A simulation analysis of a Scara robot for. different operatian conditions under different velocity trajectories is presented. Also, the velocity trajectories used in the analysis are presented and discussed.

In this paper, the location and allocation of derivative products of saffron industries, one of the strategic industries in the field of exporting non-oil goods, is studied. Since this problem is a kind of multiple attribute decision making (MADM), so we look at litrature and then choose TOPSIS method. However, as those products of saffron are significantly new and there isn't any accurate, quantity and multi aspects information, therefore, we developed the method in Fuzzy system. Finally we solved the problem and identifed the preferable cities in IRAN for location.

In this study, mechanical properties of centrifugal investment casting of commercial pure Titanium (CPT) and Ti-6Al-4V, were investigated. Vacuum system is helpful for flvoidil1g oxidation and poring. During melting and centrifugal investment casting, all parameters were kept constant, and Argon gas was also used. Two types of high frequency (Linn Type) and medium frequency (Balzerz Type) vaccume induction furnaces helped to produce defect free and required standard samples. The material of crucible and ceramic mould, the level of vacuum, centrifuge round per minute (r.p.m), reaction between melt and crucible and mould materials kept unchanged. The investment casting operations through the Near Net Shape Technology has brought about possibility of accessing to such a finalized form or sample. After' having provided with a suitable sample almost free from any technological defects, this research investigated different mechanical properties like tensile strength, impact strength, surface and distribution of hardness.

In view of the numerous instances of applications of chlorinated paraffin in industry and the existence of raw materials in the country, it is required to study the manner of laboratory production in order to determine the best reaction conditions for reaching a certain degree of chlorination. In view of the advantages of photochemical method over other methods, paraffin chlorination process by photochemical method in a photo reactor are discussed and factors affecting reaction progress such as temperature, flow rate of chlorine gas, light source and its location are discussed and examined. The results of experiment show that the best reactions conditions for chlorinated paraffin synthesis by photochemical method are 85-90oc, use of pure chlorine gas with flow rate of 285.5 MI/min for 400 mL paraffin, use of chlorine gas preheater for heating and giving light to the chlorine gas feed entering the reactor, under these conditions after 12 hours, chlorinated paraffin with light yellow color and containing 44.7% chlorine may be obtained.

One of the non destructive testing methods of crack detetion (crack location and depth) of structures is vibration analysis. In this paper vibration characteristics of a peripherally cracked pipe is considered. An analytical model which is independent of boundary conditions is used and the crack location and depth are related to the natural frequencies of the pipe. The cracked section of the pipe is modelled as a flexible element that divides the pipe into two elastic members. The local compliance of crack is obtained by using J-Integral and stress intensity factor concepts from fracture mechanics. The equations of motion with the proper boundary conditions define an eigenvalue problem, which is solved by an iterative method. To verify the model, an experiment was performed using a free-free pipe specimen. Experiments showed that there is a close agreement between experimental results and analytical model, which properly describes the transverse vibration of the cracked pipe.