International Journal of Engineering
Volume:28 Issue: 12, Dec 2015

In this study, carbon nano tubes have been successfully synthesized in a fluidized bed chemical vapor deposition (FBCVD) process over bi- metallic Co/Pd catalyst supported on MgO. The hydrodynamic studies of fluidized bed reactor has been reported in terms of pressure drop, minimum fluidization velocity and bed volume expansion to contribute to the optimization of the Carbon Nano Tubes (CNTs) production parameters in fluidized bed reactors. Minimum fluidization velocity and pressure drop, as the most important parameters, were taken into account for the investigation of the hydrodynamic behavior of the catalyst particles inside the fluidized bed and CNTs growth and deposition. The effect of carbonous gas to inert gas ratio (CH4:N2) was studied based on design of experiment (DOE) using Response Surface Methodology. It was found that N2:CH4 flow rate ratio must be 3:5 to obtain the highest bed volume expansion for maximum carbon nanotubes accumulation. The carbon nanotubes are multiwalled with diameter of 14 nm and volume bed expansion of 85% occurred when ratio of methane to nitrogen is 5:3. The optimum parameters for higher conversion of methane to CNT occurs when temperature is 1000 ◦C and the flow rate ratio of Nitrogen to methane is 3:5 in FBCVD.

The column-tree constructional scheme allows for a reliable and convenient erection of moment resisting steel frames. Strengthening of column-tree connection with a haunch part can significantly improve seismic behavior of beam-column joint. In the current study, behavior of column-tree connections with haunched beams and end plate splices have been investigated. Special attention was paid for evaluation of the effect of haunch section length and presence of the beams bottom flange. Nonlinear finite element analysis has been used for numerical analyses. The results indicate an improvement of the load bearing capacity of specimens when a longer haunch was used and also when beam bottom flange existed in the haunch part. A direct relation between haunch length and the amount of stress in splice plates was also observed. However, all connections showed ductile behavior during cyclic analysis and specimens with longer haunch revealed more desirable behavior. It was concluded that despite some deficiencies observed during the numerical tests, in presence of a longer haunch and also the beam''s bottom flange, a noticeable improvement of the general behavior of connection can be achieved.

Non-overlapping field-of-view (FOV) cameras are used in surveillance system to cover a wider area. Tracking in such systems is generally performed in two distinct steps. In the first step, people are identified and tracked in the FOV of a single camera. In the second step, re-identification of the people is carried out to track them in the whole area under surveillance. Various conventional features such as clothes and appearance of person have been used to identify peoples in the cameras. However, similarity between appearance and clothes of people causes unreliable results. Thus, much reliable features are still required to increase the ability of tracking system. The aim of this paper is to propose a novel algorithm to identify people in a network of cameras with disjoints views. In our proposed methodology, according to relative size of various parts, human body are divided into three portions of head, middle section and lower section. Considering histograms of these portions, matching process was done aiming to distinguish persons in FOV of cameras. The other main challenge in such multi-camera system is to deal with illumination changes and varying appearance of people at different camera’s view. The cumulative brightness transform function (CBTF) was employed to alleviate the difficulty of illumination changes. Experiments were conducted in RGB, YCbCr and HSV color spaces and it was found that YCbCr color space gives a better performance result compared to other color spaces used in this work.

In this paper, a steganography technique for JPEG2000 compressed images using singular value decomposition (SVD) in wavelet transform domain is proposed. In this technique, discrete wavelet transform (DWT) is applied on the cover image to get wavelet coefficients and singular value decomposition is applied on these wavelet coefficients to get their singular values.Secret data bits are embedded into these singular values using scaling factor. Different compression rates are also considered for JPEG2000 images after embedding the secret images. Genetic algorithm (GA) is used to optimize the value of scaling factor (SF). Maximum capacity of the proposed technique is 25% of cover image size and maximum peak signal to noise ratio(PSNR) values between cover and its stego image is more than the PSNR of existing techniques. Embedding capacity of proposed technique is also higher than the embedding capacity of existing techniques. Also, PSNR between secret image and extracted image is high and hence the visual quality of the extracted secret image is good enough to the human visual system. Steganalysis tests are performed on the stego images to show imperceptibility of proposed technique.

The main objective of data mining is to acquire information from a set of data for prospect applications using a measure. The concerning issue is that one often has to deal with large scale data. Several dimensionality reduction techniques like various feature extraction methods have been developed to resolve the issue. However, the geometric view of the applied measure, as an additional consideration, is generally neglected. Since each measure has its own perspective to the data, different interpretations may achieved on data depending on the used measure. While efforts are often focused on adjusting the feature extraction techniques for mining the data, choosing a suitable measure regarding to the nature or general characteristics of the data or application is more appropriate. Given a couple of sequences, a specific measure may consider them as similar while another one may quantify them as dissimilar. The goal of this research is twofold: evincing the role of feature extraction in data mining and revealing the significance of similarity measures geometric attributes in detecting the relationships between data. Differrent similarity measures are also applied to three synthetic datasets and a real set of ECG time series to examine their performance.

The trans-admittance-mode (TAM) might act as a transforming bridge for voltage-mode to currentmode conversion. In this study a new low voltage operated electronically tunable TAM biquad filter structure realizing all the seven standard filtering functions namely; low-pass (LP), band pass (BP), highpass (HP), regular-notch (RN), low-pass-notch (LPN), high-pass-notch (HPN) and all-pass (AP) from the same configuration through appropriate selection of voltage input signals is presented. The proposed circuit structure comprises of three current conveyor trans-conductance amplifiers (CCTAs). Moreover, the new biquad filter structure still enjoys (i) realizations require neither inverted, nor scaled voltage input(s), (ii) the employment of two capacitors, hence providing canonical structure, (iii) the pole frequency can be tuned electronically, and (iv) possesses low incremental active and passive sensitivity performance and useful in low-voltage low-power applications. Personal simulation program with integrated circuit emphasis (PSPICE) simulation results using 0.25μm taiwan semiconductor manufacturing company (TSMC) complementary metal-oxide semiconductor (CMOS) parameters verify the theoretical analysis.

Deriving weights from a pairwise comparison matrix (PCM) is a subject for which a wide range of methods have been presented. This paper proposes a common weight multi criteria decision analysis-data envelopment analysis (MCDA-DEA) approach with assurance region for weight derivation from a PCM. The proposed method has a more discrimination power over the conventional methods for weight derivation from a pairwise comparison matrix. Furthermore, the proposed model has several merits over the competing approaches and lacks the drawbacks of the well-known Data Envelopment Analysis HP and data envelopment analysis / assurance region methods (DEA/AR) methods. Some numerical examples and a case study are taken from the literature in order to confirm the merits of the proposed method and its applications in multi criteria decision making. Results disclose the advantages of the proposed approach.

In traditional scheduling literature, it is generally assumed that the location of facilities are predetermined and fixed in advance. However, these decisions are interrelated and may impact each other significantly. Therefore finding a schedule and facility location has become an important problem as an extension of the well-known scheduling problems. In this research we consider joint decisions on planning of machines’ layout and scheduling of jobs on each machine in a Flexible Job Shop environment. The aim is to minimize maximum completion time. The problem is formulated as a mathematical programming model and is solved using an enhanced particle swarm optimization (PSO). Furthermore, parameters of algorithm is optimized by Taguchi statistical tool. A lower bound is also devised for evaluating the obtained results.

This paper deals with the application of iterative learning control (ILC) to further improve performance of bilateral telerobotic systems based on Smith predictor. The aim is to achieve robust stability and optimal transparency for these systems simultaneously. The proposed control structure makes the slave manipulator follow the master in spite of uncertainties in time delays appeared in communication channel and model parameters of master-slave robots, called model mismatch. The time delays are considered to be large, unknown and asymmetric, but the upper bound of the delay is assumed to be known. The main aspect of the proposed controller is that a designer can use the classical controller like proportional-integrator-derivative (PID). However, one of its main difficulties is how to assign proper parameter values for the controller. In other words, the parameters of the controller are not unique and are chosen only to satisfy the stability condition. To solve this problem, in this paper, the local controller is also optimized by backtracking search optimization algorithm (BSA), which is a novel heuristic algorithm with a simple construction. Simulation results illustrate the appropriate performance of the proposed controller.

Scheduling problems with batch processing machines (BPM) assume that machines are continuously available, and no time is needed for their preventive maintenance (PM). In this paper, we study a realistic variant of flowshop scheduling which integrates flow shop batch processing machines (FBPM) and preventive maintenance for minimizing the makespan. In order to tackle the given problem, we employ reliability concept, and develop an electromagnetism-like (EM) algorithm, as an evolutionary technique, and propose an enhanced EM algorithm, in which the EM is hybridized with a diversification mechanism, and an effective local search to enhance the efficiency of the algorithm. The proposed algorithms are evaluated by comparison against two existing well-known EMs in the literature. For this purpose, we study the behavior and investigate the impacts of the rise in problem sizes on the performance of the developed algorithm. The superiority of our EM is inferred from computational results obtained in various circumstances.

In the present work, structure health monitoring (SHM) of welded steel pipes was used to diagnose their state via vibration based damage detection techniques. The dynamic quantities such as Frequency Response Functions (FRFs), mode shapes and modal parameters from structural vibration to detect damage were measured, set on linear averaging mode, with a maximum frequency of analysis of 3.2 kHz. Two most commonly used welding techniques were used, namely: shielded metal arc welding (SMAW) and gas tungsten arc welding (GTAW). Static tests were performed to assure the quality of welded steel pipes. These tests include three point bending test (3PB), face bending, and tensile testing. In addition, X- ray images were utilized as a non-destructive testing (NDT). The results showed for non-cracked pipes, having the first three modes, the higher damping frequency and the lower damping ratio. This reflects the difficulty of dissipating energy at higher frequencies. Also, it was found that SMAW gives higher damping ratio (7.418%) as compared to GTAW joints (7.220). So, the latter joints have higher stiffness than former ones. The results demonstrated that the FRFs technique is a potentially powerful tool for damage detection and health monitoring of welded steel structural pipes.

Two types of micron-diamond films were prepared on YG6 substrate by hot filament chemical vapor deposition (HFCVD) method. Morphology and orientation of crystalline growth were evaluated by Scanning Electron Microscopy (SEM) and X-ray Diffration (XRD). The surface of the diamond film-coated tools and sapphire wafer was compared before and after lapping. The Raman spectra of two micron-diamond film indicated that a significant change occurred in surface properties after lapping. This change was explained as graphitization of the diamond surface. The friction coefficient of the ZMDF was larger than that of the FMDF tool. The surface roughness of the sapphire wafer lapped by FMDF (<110> texture) was lower than that of ZMDF ( texture). Comparing the two kinds of micron-diamond film, the lapping effect of the FMCD tool was found to be better.

An evacuated tube solar collector drier is designed and developed to study analytically and experimentally drying kinetics of Thompson seedless grapes in Pune, India. Drying experiments are carried out in the month of April- June for continuous three years from 2013-2015. During the experimentation, temperatures of hot and cold air at various places, ambient relative humidity and humidity variation in drying chamber, wind velocity and mass of the grape are measured on hourly basis. 10 kg of Thompson seedless grapes are dried in forced convection heat transfer mode from initial moisture content of 76% (wb) to final moisture content of 15%(wb) in 37 hours. The drying is carried out under the uncontrolled conditions. The average evacuated tube solar collector efficiency is found to be 24.5% whereas the stacked type dryer which is insulated from outside has given drying efficiency up to 37.1%. To study drying behavior analytically nine different drying models have been tested. It is observed that, Page model describes the drying behavior accurately with highest coefficient of determination (R2 = 0.993), lowest reduced chi-square (χ2 = 5.19x10-5) and lowest root mean square error (RMSE = 0.02071).

In this paper, the non-Fourier heat conduction in a semi-infinite body was examined. The heat wave non-Fourier heat conduction model was used for thermal analysis. Thermal conductivity was assumed temperature-dependent which resulted in a non-linear equation. The heat source was also considered temperature-dependent which resulted in a non-homogeneous equation. The Mac Cormack predictorcorrector numerical method was employed to solve the equations. It was concluded that, the non linear analysis of the non-Fourier heat transfer problems is of great importance. Also, the case which assumed a temperature-dependent heat source had a considerable difference with the case in which a constant heat source was assumed.

The present work mainly studies the free vibration of circular magneto-electro-elastic (MEE) nanoplates based on Kirchhoff’s plate theory within the framework of nonlocal elasticity theory to account for the small scale effect. The MEE nano-plate studied here is considered to be fully clamped and subjected to the external magnetic and electric potentials. Using nonlocal constitutive relations of MEE materials, the governing equations are derived by applying Maxwell’s equation and Hamilton’s principle. By employing Galerkin method, the eigen matrix form of the governing equation is obtained. The effect of magneto-electric potential on instability of the system is investigated and consequently critical values of applied potentials are calculated. A detailed numerical study is conducted to study theinfluences of the small scale effect, thickness and radius of the nano-plate and piezoelectric volumefraction of the MEE material on the natural frequencies of nano-plate. Furthermore, the effects of the applied magnetic and electric potentials on the size-dependent natural frequencies are investigated numerically.