International Journal of Engineering
Volume:31 Issue: 9, Sep 2018

Density Functional Theory (DFT) calculations techniques are used to study CO2 adsorption in NH2-, OH-, COOH-, Br- and Cl-functionalized IRMOF-1. Geometry optimization, density of states (DOS), and energy analysis were performed to investigate the adsorption phenomenon. The binding properties have been calculated and analyzed theoretically for pristine H2BDC and X-H2BDC as well as their complex forms with CO2 molecule in terms of binding energies, band structures, total density of states, and Mulliken charges. The finding showed larger interaction energy in COOH-H2BDC and somewhat in OH-H2BDC and NH2-H2BDC complexes compared to less interaction energies in Br-H2BDC and Cl-H2BDC complexes.

Rubber wood (Ficus elastica) is one of the biomass waste that can be used as raw material for gasification process, and has a calorific value of 4069 cal/g. Gasification is a process to convert a solid fuels to syngas (CO, CH4, and H2) through a partially combustion process using limited air between 20% to 40% of air stoichiometry. Depending on the direction of airflow, the gasifier are classified as updraft, downdraft, and cross-flow. The downdraft type of gasifier produces a lower tar content than updraft type.The gasification of rubber wood and rubber wood-coal mixture were carried out in this research. The purpose of the research is to determine the effect of Air Fuel Ratio (AFR) and temperature on calorific value and composition of syngas using a downdraft gasifier.The variations of AFR were 0.64, 0.95, and 1.26. The temperature of gasification was varied between 600-1000ºC. The result showed that the percentage of CO, H2, and CH4 decreased with increasing of AFR and decrease in calorific value. The calorific value of syngas increased along with the temperature.The use of coal in the gasification process can maintain the stable combustion temperatures and increase the syngas produced. The best-operating conditions in this research occurred at AFR of 0.64, temperature of 800ºC and use of coal as a stabilizer.At this condition, the percentage of syngas of 35.95% of CO, 15.95% of H2, 9.38% of CH4, and caloric value of 9.42 MJ/m3 was obtained. The highest gasification yield of 35.75% was also reached.

The problem of insufficient data and uncertainty in modeling play a significant role in many engineering and management problems. Therefore, applying some techniques and decision-making processes is essential to attain proper solutions for aforementioned problems under accurate consideration. In this paper, an application of fuzzy inference system for modeling the indeterminacy involved in the problem of HSE risk assessment is presented. For this purpose, Failure Mode and Effect Analysis (FMEA), one of the most practical techniques with high reliability in HSE risk assessment is integrated with fuzzy inference system. The proposed model is executed according to the Mamdani algorithm and fuzzy logic toolbox of MATLAB software. With respect to a case study, a comparison between the proposed model and common FMEA risk assessment approach is made for prioritization of the HSE risks. The selected HSE risk factors which were analyzed are listed in three categories as follows: (a) health risks; (b) safety risks and (c) environmental risks. Based on the proposed model, falling and slipping of workers grouping with safety risks is ranked as the first serious risk with the risk priority number of 0.7938 and skin injury which is classified with health risks is considered as an inconsiderable risk with the lowest risk priority number of 0.0223. Ultimately, by applying the method on a case study, the results indicate that the proposed model by considering economic aspects as an intelligent risk evaluation tool provides more detailed and precise results.

Characterization of properties of composites has attracted a great deal of attention towards exploring their applications in engineering. The purpose of this work is to study the difference of two computational microstructure models which are widely used for determining effective transverse elastic properties of unidirectional fiber reinforced composites. The first model based on the classic mechanics of materials permits free unloaded opposite boundaries in the unit cell; while the second one introduces straight-edge constraints in the unit cell to represent interactions of neighboring cells during deformation. The two approaches are firstly verified by the periodic circular hole problems. Then three microstructures are taken into consideration including the circular fibers, square fibers, and circular fiber clusters periodically embedded in the matrix and subsequently are solved by finite element analysis. A comparison of the numerical results demonstrated that the two computational models with and without periodic conditions can give different predictions on the effective elastic properties of composite for both low and high fiber volume fractions, especially for the effective Poisson’s ratio of composite. Applying periodic straight-edge constraints after deformation can prevent any over-constrained conditions in the numerical model and give more stable results.

Typically, to study the effects of consecutive earthquakes, it is necessary to consider definite intensity levels of the first shock. Methods commonly used to define intensity involve scaling the first shock to a specified maximum interstorey drift. In this study the structure’s predefined elastic spectral acceleration caused by the first shock is also considered for scaling. This study aims to investigate the effects of consecutive far-field (FF) and near-field (NF) ground motions on the exceedance probability of different performance levels of a reinforced concrete single degree of freedom system considering the aforementioned first shock scaling methods. Eight groups of simulations are defined with each considering a combination of FF and NF ground motions. By elastic spectral acceleration as the scaling method, it is found that the exceedance probability of the second shock performance levels, especially in pulse-like records, greatly depends on the order of far/near field ground motions and the level of damage caused by the first shock. It could be inferred that although first shock scaling method to maximum drift ratio is the commonly used method, the effects of record type multiple earthquakes are more revealed using elastic spectral acceleration as the first shock scaling criteria.

The construction of flexible pavements with hot mix asphalt (HMA) consumes considerable energy, which impacts global resources and environment. Warm mix asphalt (WMA) is an effective alternative because it is produced with mixing and compaction temperatures lower than those used in HMA production. This technology decreases energy consumption, saves money and reduces the environmental pollution. Moreover, this technology can generate a revolution in sustainable construction if combined with the use of waste materials to improve the properties of WMA. Polyethylene terephthalate (PET) wastes are increasingly accumulated over the world. However, to the best of knowledge of authors, no research has adopted using PET wastes in combination with improving WMA properties. Therefore, the present study covers the usage of PET waste bottles to modify the properties of WMA. Ground PET waste bottles with a maximum particle size of 2.36 mm with different contents (0.1, 0.3, 0.5, 0.7, 0.9 and 1.1% by the weight of aggregate) were used to replace an equivalent portion of fine aggregate. Laboratory tests were conducted to investigate the effects of different PET contents on the properties of WMA. The testing programme included Marshall, rutting susceptibility and indirect tensile strength (ITS) tests. Results exhibited significant improvements in the engineering properties of the mixtures modified with the optimum PET content (which was found to be 0.5%) in terms of increase in stability, stiffness, ITS and moisture damage resistance and decrease in rutting susceptibility, without adverse effects on the other desirable properties of the mixtures.

Internet bank has limitations such as access to the internet network and personal computer (PC). In addition to provideeasily bank services to customers at any time, The provision of mobile phone services with the title of Mobile Bank was introduced to eliminate these restrictions and limitations. Due to importance of technology adoption by users, in this research, the technology acceptance model was developed by taking into account the variables of the original model, by adding new variables such as risk perception, cost perception, trust, resistance, compatibility while examining the proposed models. This research has analyzed the statistical population using the questionnaire. Finally, by analyzing obtained results, with regression analysis observed that individual's age has not much effect on the technology adoption according to results, and also individuals do not have much resistance to adopt the technology in this period, which leads to adopt more new technologies. Individuals are also willing to pay for the services and technology used while benefiting from its advantages. The cost has not affected the attitude of individuals and is not an impediment and barrier to technology adoption, and ultimately, individuals have adopted the risk of use of technology. This issue does not damage their trust in new technology.

Voiced-based age detection and gender recognition are important problems in the telephone speech processing to investigate the identity of an individual. In this paper, a new gender and age recognition system is introduced based on the generative incoherent models learned using sparse non-negative matrix factorization and the atom correction step as a post-processing method. The proposed classification algorithm includes training step to provide the appropriate trained atoms for each data class and also the test phase to assess the classification performance. Since the classification accuracy depends highly on the selected features, the Mel-frequency cepstral coefficients are employed to train basis for the better representation of the voice structure. These bases are learned over the data of male and female speakers using non-negative matrix factorization with the sparsity constraint. Then, atom correction is carried out using an energy-based algorithm to decrease the coherence between different categories of the trained dictionaries. In the sparse representation of each data class, the atoms related to other sets with the highest energy are replaced with the lowest energy bases if the reconstruction error does not exceed from a specified limit. The experimental results showed that the proposed algorithm performs better than the earlier methods in this context especially in the presence of background noise.

The sensorless model predictive force control (SMPFC) is a strong method for controlling the drives of three-phase 4(6)-switch inverter linear induction motors. This kind of inverter can be employed for the fault tolerant control in order to solve the problem of open/short circuit in the 6-switch inverters (B6). This paper propose a method for the SMPFC of a linear induction motor (LIM) fed by a 4-switch inverter fed along with DC-link voltage offset reduction. Simulations have been performed on several different LIMs in MATLAB software to determine the weight coefficients of stator flux and reduction of the capacitor voltage offset. Then, a relationship has been proposed for determining the weight coefficients in the cost function of the SMPFC. By using weight coefficients in the cost function, the B4 inverter voltage vectors are obtained for exact prediction. The balance of currents is improved by determining the appropriate value for the weight coefficient of the capacitor voltage offset reduction. Simulation results are provided for validation of the suggested control method.

The presence of package inductance induces large voltage fluctuation (bounce noise) on the power rail during power down to power up transition in the power gating circuit that may cause unwanted transitions in neighboring circuits. In this work, a power gating architecture is developed for minimizing power in active mode. Noise for the architecture has also been analyzed. The effect of various noise minimization approaches for reducing power supply noise have been evaluated in power gating architecture. A new concept of noise minimization technique using Low Dropout Voltage Regulator has been proposed in this paper. The amount of charge in the internal nodes that passes through the sleep transistor during the wake-up transition has been controlled by the proposed noise minimization techniques. The Low Dropout Voltage Regulator is designed with a target of reducing bounce noise by minimizing voltage fluctuations on the power rail. Low noise active mode power gating architectures have been designed in Synopsys Custom Designer tool at iPDK 90nm technology. Saving of noise at the power supply rail has been observed up to 99%.

This paper presents a two-stage low-noise ultra-wideband amplifier to obtain the high and smooth gain in 180nm CMOS Technology. The proposed structure has two common source stages with inductive feedback. The first stage is designed for 3GHz frequency and the second stage is designed about 8GHz. In the simulation, symmetric inductors of TSMC 0.18um CMOS technology in ADS software is used. Simulation results show high and relatively smooth S21 equal to 18.674±1.38dB, the noise figure of less than 3.7dB, the power consumption of 14.6mW with 1.2V supply voltage and suitable matching at the input (S11<-10.8dB) in 3.1 to 10.6 GHz frequency range. Moreover, IIP3 of this circuit is -9.5dBm at the 7GHz frequency.

Nowadays, the importance of the vehicles and its dramatic effects on transportation system is obvious. The use of trailers with multiple axels for transporting bulky and heavy equipment is essential. Stability and steerability of trailers with multiple axels and wheels is one of the main concerns in the transportation system. Therefore, in this paper dynamic modeling and control of a 5 axial trailer was studied. As well as to increase maneuverability and speed up, 3 axles was considered to be steered. Also, by using image processing trailer path following in desired path with the highest accuracy was achieved. In this study, first a 14 DoF model for a 5 axial trailer with 3 steering axles was considered and its dynamic was formulated. For this purpose, dynamic equations including kinematic and kinetic of trailer was obtained. Then, with evaluating trailers response, a linear quadratic optimal control algorithm was designed. In order to evaluate the performance of the control algorithm, control problem simulation for single lane change and overtaking was done. The results confirmed the performance of designed control algorithm and image processing accuracy in trailer path following.

Generally, the inventory routing problem occurs in a supply chain where customers consider the supplier responsible for inventory replenishment. In this situation, the supplier finds the answer to questions regarding the time and quantity of delivery to the customer as well as the sequence of customers in the routes. Considering the effect of production decisions on answering these questions, the present paper examines the integrated decision making on production, routing and inventory in a two-echelon supply chain composed of a manufacturer and multiple retailers. Transshipment, as a policy in supply chain logistic which increase integration and decrease inventory cost, is also allowed between retailers. The mathematical formulation for the problem is developed and an adaptive large neighborhood search heuristic is proposed to solve this complicated problem. The results of numerical experiments showed that the solutions yielded by the heuristic method have high efficiency.

In this paper, the strategic planning of a supply chain under a static chain-to-chain competition on the plane is addressed. It is assumed that each retailer has a coverage area called the radius of influence. The demand of each demand zone is divided equally between the retailers which can cover that market. However, the demand of distant customers who are not in the retailers’ radius of influence, will be lost. This competition is modelled for a real case application of a super-market chain. It is assumed that the chain’s owner wants to expand retail outlets to improve its market share. Since this expansion could affect the current customers of existing retailers, the owner wants to avoid attacking the market share of its current retailers. A bi-objective fuzzy mixed integer nonlinear model is proposed. For solving the model, it is first reformulated to a mixed integer linear program and then an interactive approach is devised to handle the fuzzy bi-objective model. Four expansion strategies are analysed from which useful managerial insights are drawn.

In this paper, size dependent nano-beam type peizoelectric energy hardvester is investigated. For this goal, first nonlinear formulation of isotropic piezoelectric Euler-Bernoulli nano-beam is developed based on the size-dependent piezoelectricity theory then special nano-beam type piezoelectric energy hardvester is probed for different parameters. Basic nonlinear equations of piezoelectric nano-beam are derived using principle of minimum potential energy and variational method. To evaluate the formulation derived, static deformation and free vibration of the hinged-hinged piezoelectric nano-beam is investigated in the special case. The results of the derived formulation are investigated under different parameters, and particularly, the ability and performance of the beam type piezoelectric low power energy harvesting was evaluated in nanoscale.

In this paper, a new approach to optimize an Autonomous Underwater Vehicle (AUV) hull geometry is presented. Using this methode, the nose and tail of an underwater vehicle are designed, such that their length constraints due to the arrangement of different components in the AUV body are properly addressed. In the current study, an optimal design for the body profile of a torpedo-shaped AUV is conducted, and a multi-objective optimization scheme based on the optimization algorithm Non-dominated Sorting Genetic Algorithm-II (NSGA-II), as an evolutionary algorithm is employed. In addition, predefined geometrical constraints were considered so that equipment with the specific dimensions can be placed inside the AUV space without any effect on the AUV volume and the wetted surface. By optimizing the parameters of the newly presented profile, in addition to maximizing the volume and minimizing the wetted surface area, more diversed shapes can be achieved than with the ‘Myring’ profile. A CFD analysis of the final optimal design indicates that with the help of the proposed profile, the hydrodynamic parameters for the AUV hull were effectively improved.

In this work, cold bulge forming of an Aluminium-Magnesium (Al-Mg) sheet with a solid bulging medium is experimentally and numerically performed. Mechanical properties and thickness variations of Al-Mg sheet are evaluated before and after the forming process. The results indicated that the Al-Mg sheet has taken the desired shape without necking using the cold bulge forming process. Also, the experimental results showed significant improvements of 13 and 9.7% in yield and ultimate tensile strengths of Al-Mg sheet after bulge forming. It is proved that the maximum thickness reduction of Al-Mg blank is less than 6% after cold bulge forming. Numerical simulations of cold bulge forming of Al-Mg sheet are conducted using Abaqus finite element software. For this purpose, many numerical models were created and analyzed to investigate the effects of bulge forming speed on the blank thickness variation for different Aluminium alloys. In these simulations, four different speed of 1, 5, 15 and 25 mm/min are used as forming speeds. Numerical results of bulge forming of Al-Mg sheet were compared with experimental measurements and good correlation, less than 2.6% difference at critical zone, was observed between the results. Moreover, obtained results from numerical simulations for different Aluminium alloys showed that the thickness variations of formed Al-Mg sheet are more uniform by reducing the forming speed. Note also that, the less strength of material, the more uniform thickness variation is achievable along longitudinal direction of metal sheet.