Simultaneous parametric optimization of micro-EDM drilling of brass C360 using Taguchi based grey relation analysis

Micro-EDM (Electro Discharge Machining) is widely used for precision manufacturing and drilling micro-holes in materials used in fuel nozzles, micro sensors and robots, surgical instruments, turbines etc. Present paper deals with drilling common C360 brass components by micro-machining and optimizing the process parameter using a hybrid approach of design of experiments (DoE) and grey relation analysis (GRA) concept. The three process responses considered are material removal rate (MRR), tool wear rate (TWR) and taper in drilled hole while the four selected controllable process parameters are capacitance(C), voltage(V), feed rate(f) and rotational speed of electrode (N). Significance of input factors on each response is analyzed with the help of a 24 full factorial by conducting 16 experiments at two levels for factors. Optimum levels of robustness for each process response are established through Taguchi’s S/N ratio. A combined grey relation grade is applied to find the process levels conducive for optimizing MRR and TWR simultaneously.

Dual-mode multifunction filter realized with a single voltage differencing gain amplifier (VDGA)

This article presents the dual-mode multifunction biquad filter realized employing only a single voltage differencing gain amplifier (VDGA), one resistor and three capacitors. The proposed filterwith one input and three outputs can configure as voltage-mode or current-mode filter circuit with the appropriate input injection choice. It can also synthesis the three standard filter functions, which are highpass, bandpass, and lowpass responses without modifying the circuit configuration. Orthogonal adjustment between the natural angular frequency (o) and the quality factor (Q) of the filter is achieved. Detail analysis of non-ideal VDGA effects and circuit component sensitivity are included. The circuit principle is verified by means of simulation results with TSMC 0.35-m CMOS process parameters.

Corrosion investigations of Al-Si casting alloys in 0.6 M NaCl solution

This paper presents results of the corrosion investigations of specimens made from finished parts for the automotive industry, produced by high-pressure die casting and gravity die casting process of six Al-Si alloys (40000 series). Open circuit potential and potentiodynamic polarization measurements have been performed using a potentiostat with three-electrode set-up in 0.6 M NaCl naturally aerated solution. Microstructural characterization before and after electrochemical investigations has been carried out with optical microscope to establish the connection between microstructure and corrosion parameters of investigated alloys and to analyze and record surface changes of each sample due to electrochemical corrosion. All alloys show good corrosion resistance, which manifests with low values of corrosion rates, calculated from the corrosion current densities obtained from potentiodynamic polarization measurements. Differences in electrochemical behavior appear due to the distinctions in their chemical composition and microstructure. The type of casting process does not affect electrochemical behavior of Al-Si alloys.

Effect of radial impeller size in the presence and absence of baffles on the copper exchange on zeolite NaX

Effect of hydrodynamics on ion exchange in a batch reactor is still not appropriately studied even though proper mixing parameters may considerably affect the process of solid suspension and its costs. In this work, hydrodynamic conditions generated by straight blade turbine (SBT) impellers on suspension in the batch reactor with and without baffles were investigated. The aim of this work was to analyze influence of impeller diameter and zeolite mass on just suspended impeller speed, (NJS) power consumption, maximum amount of copper exchanged onto zeolite NaX and copper exchange kinetics as well. All experiments were conducted at the same temperature, initial concentration of the copper solution and zeolite particle size. The obtained results showed that just suspended impeller speed decreases as impeller diameter increases in the reactor with and without baffles but this trend is considerably more pronounced in the reactor with baffles. The increase in zeolite mass causes a slight increase of NJS in the both reactor. In the reactor with the baffles this increment became noticeably higher as impeller diameter decrease. Power consumption, at the state of complete zeolite suspension, decreases as impeller diameter increases and its values in the reactor without baffles are considerably lower as well. Kinetics results indicated that the amount of copper ion increases significantly in the initial stage and then gradually until the equilibrium is reached for all hydrodynamics conditions and mass of zeolite examined.

A comprehensive study of diagnosis faults techniques occurring in photovoltaic generators

Recently, many focuses have been done in the field of renewable energies, especially in solar photovoltaic energy. Photovoltaic generator, considered as the heart of any photovoltaic installation, exhibits sometimes malfunctions which involve degradations on the overall photovoltaic plant. Therefore, diagnosis techniques are required to ensure failures detection. They avoid dangerous risks, prevent damages, allow protection, and extend their healthy life. For these purposes, many recent studies have given focuses on this field. This paper summarizes a large number of such interesting works. It presents a survey of photovoltaic generator degradations kinds, several types of faults, and their major diagnosis techniques. Comparative studies and some critical analyses are given. Other trending diagnosis solutions are also discussed. A proposed neural networks-based technique is developed to clarify the main process of diagnosis techniques, using artificial intelligence. This method shows good results for modelling and diagnosing the healthy and faulty (shaded) photovoltaic array.

The analysis of material removal rate of WEDM miniature gears

Gear fabrication in wire electrical discharge machining (WEDM) plays an important role in manufacturing industries. This paper describes the analysis and optimization of process parameters for the fabrication of spur gear on brass spur gear on brass workpiece (10cmx15cmx6mm) material by wire EDM process. The experiments were performed by using the design of experiment (DoE) approach and the material removal rate (MRR) was analyzed by response surface methodology technique. The effect of input parameters i.e. pulse on time, pulse off time and feed rate on MRR has been investigated. The surface geometry of the gears has been analysed by the Scanning Electron Microscopy (SEM). This study found that 0.4 μs for pulse on time, 60 μs for pulse-off time and 6 mm/min for feed rate provides improved material removal rate. The analysis of variance shows that pulse on time and feed rate are the significant parameters for the wire EDM process. The SEM image exhibits the capability of WEDM to machined miniature gear with a uniform distribution of regular-shaped craters and defect-free flank surface.

Effect of different types of waste materials used between double glazing box to isolate fatigue test machine noise

This study examines air, recycled plastic grains, fibers from rubber shreds and sawdust fibers as sound insulation materials to attenuate sound produced from continuous working lab fatigue test machine. These waste materials are filled in between a double glazed-aluminum framed box. The sound attenuation is tested at three studied 0.5, 1.0 and 1.5 m distances. Since the sound wave is propagated in three dimensions, the experimental work is employed in four upper, fronts, motor and sample fixture side directions. Moreover, the study is extended to examine temperature increase due to enclosing. Tests of sound level are carried out with closed and opened inlet and outlet designed slotting according to a box size. Gradual sound attenuation reaches 18, 20, 22 and 25% for air, plastic grains, rubber and sawdust fibers, respectively. The present work proves that waste materials are efficient in noise removal from sound sources. Also, they help the environment cleanliness from synthetic disposable bottles and tires as well as bio-wood wastes and assist the sustainability of earth.

Adaptive proportional-integral fuzzy logic controller of electric motor drive

This paper presents the indirect field vector control of induction motor (IM) which is controlled by an adaptive Proportional-Integral (PI) speed controller. The proposed solution can overcome the rotor resistance variation, which degrades the performance of speed control. To solve this drawback, an adaptive PI controller is designed with gains adaptation based on fuzzy logic in order to improve the performances of IM with respect to parameters variations, particularly the rotor resistance (Rr). The proposed control algorithm is validated by simulation tests. The obtained results show the robustness towards the load torque disturbances and rotor resistance variation of the adaptive Proportional-Integral fuzzy logic control with respect to classical PI control, and adaptive control based on rotor resistance observer.

Adaptive decoupling control for binary distillation column into a 3D virtual environment

The oil refinery plants have a particularly high energy consumption in the distillation process. Several authors state that these are the systems with the highest energy consumption in the petrochemical industry. Currently, work is being done on the implementation of adaptive controllers in order to improve the efficiency of the distillation process and the quality of the product. In this work the control of a binary distillation column developed within a 3D virtual laboratory is presented. Adaptive control by reference model (MRCA) is used for the manipulation of bottom and distillate concentrations. Initially, the mathematical description of the process is obtained, together with the computer-aided design, to subsequently implement the control technique. As a result, the behavior of the controlled system in simulation is shown and compared with the response of the embedded system within the virtual environment. The main contribution of this work is the interaction that a user can have with this type of processes and the possibility of implementing modern control strategies within this type of environments as a low-cost tool to support education and training activities.

Fracture analysis of a nonhomogeneous beam with two concentric cylindrical longitudinal cracks

This paper is concerned with the analysis of the fracture behaviour of a nohomogeneous cantilever beam with two concentric longitudinal cracks. The beam has a circular cross-section with linearly varying radius along the beam length. Moreover, the beam exhibits continuously varying material inhomogeneity in the radial direction. The fracture is analyzed in terms of strain energy release rate assuming nonlinear mechanical behaviour of the material. For this purpose, solutions for the strain energy release rate are derived by considering the energy balance. Two cantilever beam configurations with different lengths of longitudinal cracks are analysed. Moreover, the two cracks are arranged arbitrarily in the radial direction. The longitudinal fracture behaviour of the beam is also analysed by considering the complementary strain energy for verification. The strain energy release rate solutions are used to investigate the influence of varying radius of the cross section along the length of the beam on the longitudinal fracture behaviour. The effects of crack lengths and the location of the two concentric cracks in the radial direction on fracture are also studied. The influences of the loading conditions of the beam and the inhomogeneity of the material in the radial direction on the fracture behaviour are also evaluated.