International Journal of Engineering
Year:2014 | Volume:27 | Issue:11 (TRANSACTIONS B: APPLICATIONS)|Papers Count:18

Calibration of model is a critical role for hydrologic modeling in a large mountainous watershed. In this study, Soil and Water Assessment Tool (SWAT) was calibrated in single-and multi-site approaches to simulate stream flow. In single-site calibration, a stream flow measurement at outlet of watershed was used for calibration of SWAT. Whereas in multi-site calibration approach, we used stream flow measurements at three stations namly Galinak, Joestan and Dehdar stations. The results showed that the single-site calibration was able to sufficiently simulate the stream flow for Galinak, Joestan and Dehdar stations (Nash-Sutcliffe criteria (NS: 0.66-0.81). The results of multi-site calibration method also showed slight improvement in Galinak, Joestan and Dehdar stations, whereas it was improved in upper stations i.e. Joestan and Dehdar (NS: 0.70-0.82). But, in validation period, there were clearly adventage of results provided using multi-site calibration procedure (NS: 0.78, 0.63 and 0.64 for Galinak, Joestan and Dehdar stations, respectively) compared to single-site calibration method (NS: 0.74, 0.61 and 0.50 for Galinak, Joestan and Dehdar stations, respectively). The results of this study showed that the multi-site calibration method improved calibration of SWAT.

This paper presents an implementation of open loop and closed loop control of quadratic boost converter (QBC) using PID-controller. QBC consists of boost converter and fly back converter driven by a single switch. QBC is designed especially for regulating the DC interface between various micro sources and DC-AC inverter to electricity grid. QBC, P, PI and PID-controller are modeled, compared and evaluated by MATLAB simulation. It has been found that the transient and steady state performance is improved using PID-controller. This converter achieves high step-up voltage gain with appropriate duty ratio and low voltage stress on the power switch. The simulated open loop and closed loop performance is verified experimentally.

The redundancy allocation is one of the most important and useful problems in system optimization, especially in electrical and mechanical systems. The object of this problem is to maximize system reliability or availability within a minimum operation cost. Many works have been proposed in this area so far to draw the problem near to real-world situations. While in classic models the system components are assumed to have two states of working and failed, in this paper, parallel components of serial sub-systems are considered to work in three states, each with a certain performance rate. The component states are classified into two working states of working with full performance and working with half performance, and a failed state. Besides, technical and organizational activities are considered to improve the performance of the components as well as the sub-systems. As the problem belongs to the class of NP-hard, a genetic algorithm is utilized to solve it.

This paper proposes a compromise model, based on a new method, to solve the multi-objective largescale linear programming (MOLSLP) problems with block angular structure involving fuzzy parameters. The problem involves fuzzy parameters in the objective functions and constraints. In this compromise programming method, two concepts are considered simultaneously. First of them is that the optimal alternative is closer to fuzzy positive ideal solution (FPIS) and farther from fuzzy negative ideal solution (FNIS). Second of them is that the proposed method provides a maximum ‘‘group utility’’ for the ‘‘majority’’ and a minimum of an individual regret for the ‘‘opponent’’. In proposed method, the decomposition algorithm is utilized to reduce the large-dimensional objective space. A multi objective identical crisp linear programming is derived from the fuzzy linear model for solving the problem. Then, a compromise solution method is applied to solve each sub problem based on TOPSIS and VIKOR simultaneously. Finally, to illustrate the proposed method, an illustrative exampleis provided.

This paper examines and compares various manufacturing policies which a manufacturer may adopt so as to improve the performance of a supply chain under vendor managed inventory (VMI) partnership. The goal is to maximize the combined cumulative profit of supply chain while minimizing the relevant inventory management costs. The supply chain is a two-level system with a single manufacturer single retailer at each level, in which the manufacturer takes the responsibility of overall inventories of supply chain. A base system dynamics (SD) simulation model is first employed to describe the dynamic interactions between the variables and parameters of manufacturer and retailer under VMI. Then, the mentioned policies are constructed using the base SD model that lead us to differentiate the behavior of supply chain members for each policy within the same duration of time. In this paper, we use continuous K-nearest neighbor (CKNN) as one of the instance-based learning methodologies to predict the best manufacturing rates. This algorithm effectively increases the combined profit of supply chain in comparison with other two policies discussed in this study. Accordingly, a numerical example along with a number of sensitivity analyses are conducted to evaluate the performance of proposed policies.

Biodiesel is an attractive alternative fuel because of its nontoxicity and biodegradability. Biodiesel is produced through transesterification of vegetable oils’ triglyceride. It is obtained from vegetable oils or fats either by chemical or enzyme-catalyzed transesterification with methanol or ethanol. Use of whole-cell biocatalyst immobilized within biomass support particles (BSPs) can overcome the obstacle of high cost of enzymatic catalyst. The objective of this research is to produce clay foam ceramic as BSP by replica method from raw materials such as clay, sodium silicate and sodium tripolyphosphate. To prepare the whole cell biocatalyst Rhizopus oryzae fungi (PTCC 5174) was immobilized on the ceramic foam with bulk density and porosity of 0.3 g/cm3 and 88.8%, respectively. The deposited biomass on clay foam particles can be observed through scanning electronic microscopy (SEM). A packed-bed reactor (PBR) system using whole-cell biocatalyst was developed for biodiesel production by pretreated used cooking oil (UCO). Clay foam ceramic seems to be more suitable compared to polyurethane foam for supporting fungi immobilization because it shows high mechanical strength and reduces damaged microorganisms.

A new sorbent has been developed by grafting Hexamethylenetetramine on a mesoporous molecular sieve (SBA-15) by wet impregnation method. This sorbent (Hexamine/SBA-15) has been characterized using N2 physisorption, X-ray diffraction (XRD) at low angles (2qo) and FT-IR. To investigate the H2S removal capacity of this adsorbent from 9000 ppm H2S balance CH4-containing gas mixtures, the breakthrough tests have been performed on a fixed-bed flow system. SBA-15 without amine loading showed a very low H2S adsorption capacity (0.015 mmol-Sulfur/g-sorbent) and saturation capacity (0.032 mmol-Sulfur/gsorbent). The results show that after the amine loading, hexamine is dispersed inside the mesochannels of mesoporous SBA-15. Effects of the amine loading and sorption temperature on the sorption behavior of this developed sorbent have also been studied. Increase of amine loading enhances the H2S sorption on this sorbent, When Hexamine was 50 wt%, the removal performance was optimum(qb= 0.9 mmol/gsorbent). With increase in temperature, both the breakthrough capacity (qb) and the saturation capacity (qs) decrease. High sorption capacity is observed at low temperature (T=22oC, qs= 1.9 mmol/g-sorbent) which provides a promoting effect in removal of H2S from gas mixtures streams on the developed Hexamine/SBA-15 sorbent. This developed sorbent is regenerated easily at 100oC, and shows very good stability. The breakthrough capacity decreased from 0.9 mmol. g-1 for the first cycle to 0.75 mmol g-1 for the second cycle and 0.74 mmol g-1 for the third cycle. Although the breakthrough capacity decreased about 83 % of the first breakthrough tim, H2S can be recovered.

One of the processes of submerged arc welding is back gouging operations. This work, in addition to implementing high cost, requires to consuming much time in production line as well as environmental and acoustic pollutions which has with itself. This paper presents a way to remove the back gouging operation from the submerged arc welding process. For this purpose, effects of submerged arc welding parameters on A516-70 steel sample were investigated. 16 and 18mm thickness sheets without chamfering were prepared and by choosing the best parameters, they were welded from face and back. Also, the effects of stress-relief heat treatment and preheat were investigated. Microstructure and mechanical properties were in standard situation and shows the performance of this project. Removing the back gouging operation significantly reduced the cost, time and also reduced noise and environment pollution in submerged arc welding process. By implementation of this design, we will observe 80% reduction in costs welding and also elimination of the environmental and acoustic pollutions which are resulted from back gouging.

The solar photovoltaic (PV) systems are facing serious problems due to unavoidable losses in their system, leads to more deviation of output power from the input power level. This effect is known as a mismatch effect and is available in PV systems. Many losses are encountered in PV system and it is difficult to minimize such losses. In this paper, the influence of thermal effect on the solar PV system is considered and its influence on the performance of the operation, fill factor, open circuit voltage, and short circuit current, band gap level of various semiconductor materials, output power and efficiency are analyzed. The temperature effect of a solar PV cell, while connecting in a 36 cells in a module is analyzed for the various connection configurations like Simple Series configuration (SS), Series- Parallel configuration (SP), Total-Cross Tied configuration (TCT), Bridge-Linked configuration (BL), and Honey Comb configuration (HC) using MATLAB software. An increase in the level of temperature for various connection configurations, correspondingly decreases their open circuit voltage and series resistance. Shunt resistance and current are may not fully affected due to temperature. Finally, this problem creates a heating effect in the solar PV cell, so the life span of the photovoltaic panel is decreased gradually. While the temperature level increases, soldering points are affected and cell encapsulation is affects. Solar cell materials are changed their performance of operation, while there is a change in the band gap due to the effect of temperature.

An experimental setup is designed to detect composite delamination damage based on ultrasonic infrared thermography. The ultrasonic infrared thermography system is composed by ultrasonic excitation system, infrared thermal imager and data acquisition system and two damaged composite plate specimens are produced in the experiment. The image processing methods including thresholding, filters, edge detection and morphological processing method are combined to analyze infrared thermal images and accurately identify the location and size of the delamination damage. The temperature changes of defective composites under different preload of ultrasonic excitation are analyzed. The experiments demonstrate that the ultrasonic detection has the effect of the selection of heating in the defective area of the composite. The experimental results come to the conclusion that the ultrasonic infrared thermography is an effective quantitative method to detect the composite delamination damage.

In this paper, one of the simplest and most regular members of the family of the Meshless Local Petrov-Galerkin (MLPG) methods; namely MLPG5, is applied to analyze the thick-walled isotropic laminated cylinders under elasto-static pressure. A novel simple technique is proposed to eliminate a very important difficulty of the meshless methods to deal with material discontinuities regarding to the high continuity of their shape functions. The Moving Least Squares (MLS) approximation is used for constructing the trial functions, and a simple Heaviside step function is chosen for the test function. The direct interpolation method is employed to impose the essential boundary conditions. Acceptable agreements with the analytical solutions and finite element method results are obtained specially at the material discontinuity boundaries, which suggest its application in other classes of problems.

This article reports the effective usage of redmud (RM), an industrial waste, as a novel filler in polymer matrix. The composite has been fabricated with redmud as secondary reinforcement in banana fiber reinforced polyester (BFRP) using compression molding technique. The mechanical properties such as tensile, flexural and impact strength have been studied for different fiber weight percentage, weight percentage of red mud and chemical treatment of fiber. It is observed that the addition of 10 wt percent of redmud improves the impact and flexural properties for both NaOH, silane treated and untreated banana fiber but there is a decreased trend for tensile strength. It is also found that banana fiber particulate composites have superior mechanical properties than the banana/polyester. Addition of redmud to the banana fiber decreases the moisture absorption of the composites. The studies of the scanning electron microscopy (SEM) have been done to know the fracture mechanism.

Hydrogen has been known as a clean and suitable fuel to replace conventional fossil fuels. One of the common hydrogen production methods is using water electrolysis process. This method produces oxygen as well as hydrogen by ratio of 1:2. The aim of this work is to investigate the effects of inlet air enrichment by adding produced hydrogen and oxygen to an internal combustion engine. For this purpose, an electrolysis system consisting of four cells have been built and the produced gas mixture was transferred to the inlet manifold of the engine via a rubber hose. The experimental results showed that addition of hydrogen and oxygen to the inlet air under full load can cause reduction in CO and hydrocarbon gas (HC) by 21% and 19% respectively, and increases power and torque by 5.5% under similar conditions.

In the development of Homogeneous Charge Compression Ignition (HCCI) engines, simultaneous control of combustion phasing and power output has been a major challenge. In this study, a new strategy is developed to control the engine power output and combustion phasing at any desired operating condition. A single zone thermodynamic model coupled to a full kinetic mechanism of Primary Reference Fuels (PRFs) is developed to predict characteristic parameters such as; Start of Combustion (SOC) and Indicated Mean Effective Pressure (IMEP) and also thermodynamic constant parameters for processes through an HCCI engine cycle. A dynamic interactive control model has been developed for the entire cycle of a HCCI engine to predict combustion phasing and IMEP. The results derived from the developed model are validated against experimental data for a single cylinder Ricardo engine. A two input - two output controller is then designed to track crank angle at which 50% of in cylinder fuel mass is burned (CA50) and IMEP by adjusting the input data. In this study two control models are presented; open loop and closed loop. Performance of the controller is tested on a physical HCCI engine model to evaluate the tracking performance and disturbance rejection properties. Results indicate that the designed controller is capable to accurately tracking both CA50 and IMEP while rejecting the disturbances from variations in the engine speed and the intake manifold temperature.

Being sustainable and producing little waste products, the renewable energy knows a rapid deployment. Unfortunately, the intermittent characteristic of these energies makes them difficult to control. The influence of this aleatory character can be reduced with the coupling of two or more sources of renewable energy and secondly with a sound management of storage systems. This new configuration of production and energy management is the target of our research. The objective of this paper is to construct a model of a multi-sources system feeding a domestic house with the multiphysics approach which enables us to model, simulate and control all components and subsystems in our system consisting of wind turbine, solar panel and storage system with battery. This system feeds a domestic house. To achieve this objective, firstly, a system description is presented. Secondly, a SIMSCAPE model for the multisource system is developed in the MATLAB/SIMSCAPE software. Finally, results are derived from simulations.

The simple passive dynamic walker can walk down a shallow downhill slope with no external control or energy input. Nevertheless, the period-one gait stability is only possible over a very narrow range of slopes. Since the passive gaits are extremely sensitive to slope angles, it is important to use a control strategy in order to achieve a wide range of stable walking. The computed torque method is proposed here to produce stable period-one gait cycles for different slopes. In present method, the unstable walking gait is stabilized by a stable period-one gait pattern on a small specific slope. The proposed approach is illustrated by the simplest passive walkers with point and curved feet. Simulation results reveal the usefulness of this control method for improvement in stability properties of the models.

Fixture design is a crucial part of manufacturing process. Fixture design is a critical design activity in which automation plays an integral role in linking computer-aided design (CAD) and computer-aided manufacturing (CAM). This paper presents a literature review in computer aided fixture design (CAFD) in terms of automation and optimization techniques over the past decades. First, the reason behind necessity of automated fixture design is stated. According to the degree of automation, fixture design methods are then categorized based on significant works done in the CAFD field. Regarding the need of automated fixture design systems, optimization techniques, which are mostly used for automated CAFD methods, are closely considered. The significant optimization techniques are then studied in case of applications and working principles. At the end, the current weaknesses of the existing methods and the research fields, which require deeper studies as future trends are presented as well.

Based on the engineering background of Daye Iron Mine in Central China`s Hubei Province, the deformation mechanism and influence area of wall rock in the process of open pit to underground mining with high-steep slope was studied using physical model test and numerical simulation. Firstly, the selected typical section of the research was generalized, the physical model built with similar materials, special methods used to simulate the mining practice, dial indicators and digital camera measurement used to monitor the model deformation during the whole mining process. Secondly, the numerical model was built and the mining practice simulated using numerical simulation software to verify the results of physical model tests. The results indicate that the final failure of wall rocks appear at the areas nearing the ore body and does not have great influence on the stability of underground slope, the wall rock displacements of model increase slowly with increasing the mining depth. The displacements change laws of rocks nearing the faults are the same as other rocks at the same depth; the results of physical model test are generally in agreement with the numerical simulation.