International Journal of Engineering
Volume:29 Issue: 11, Nov 2016

V2O5/SiO2 catalyst was utilized to oxidize SO2 to SO3 species in the presence of oxygen mainly for producing sulfuric acid. For this catalyst, the active phase was a mixture of vanadium pentoxide and basic sulfate/pyrosulfate material. This active phase at the reaction temperature behaved as a liquid filling up the pores of the silica support. On the other hand, amounts of the SO3 and V5 species in the catalyst necessarily varied with the concentration of the feed material and temperature rendering complexity to the kinetics of the SO2 oxidation reaction. In the current research, the catalyst preparation with different amounts of such materials was undertaken. Purified diatomaceous earth of a Persian Gulf beach was chosen as the support for this catalyst. The suitability of the prepared catalyst to determine the reaction kinetics was confirmed through the XRD, XRF and BET-BJH analyses as well as color analysis. Moreover, the aforementioned reaction kinetics was studied empirically. In addition, a model for the reaction rate using the response surface methodology (RSM) was presented. In this venue, factors including the reaction temperature as well as conversion were considered. This reaction kinetics determined at the operating conditions of 380-420 °C, 0.108 MPa and feed gas composition of 10 wt.% SO2, 18.9 wt.% O2 and 71.1 wt.% N2. It was revealed that, obtained kinetic rate constants satisfied the Arrhenius relationship from which the activation energies were determined.

Membrane contactor using amine based absorbents is an efficient technology for CO2 separation from gaseous mixtures. A novel porous polysulfone (PSF) flat membrane was prepared via non-solvent phase inversion method. The PSF membrane was modified by adding polyvinyl pyrrolidone (PVP) to the dope solution. The fabricated membrane was used in the serpentine flow field contactor module for CO2 absorption. The membranes were characterized through scanning electron microscopy (SEM), atomic force microscopy (AFM) and contact angle analyses. The SEM results revealed that PVP-modified PSF membrane had a finger-like structure while the PSF membrane showed a sponge-like structure. AFM data and contact angle analysis demonstrated that the membrane porosity, surface roughness and hydrophobicity enhanced when PVP was added to the dope solution. These favorite specifications resulted in better CO2 absorption flux of PVP-modified membrane which was 133% higher than that of unmodified PSF membrane. Different gas and liquid flow rates and absorbent concentration employed during CO2 absorption experiments, demonstrated that increasing these parameters caused a great improvement in mass transfer rates of carbon dioxide. Investigation on mass transfer resistances presented an each individual phase, indicating that by increasing the flow rate of gas phase its contribution to overall mass transfer resistance significantly reduced which indicated that the predominant resistance was in the gas phase. In comparison, the mass transfer coefficient achieved using the PVP-modified PSF membrane was remarkably greater than that of PSF membrane.

The limiting velocity in open channels to prevent long-term sedimentation is predicted in this paper using a powerful soft computing technique known as Extreme Learning Machines (ELM). The ELM is a single Layer Feed-forward Neural Network (SLFNN) with a high level of training speed. The dimensionless parameter of limiting velocity which is known as the densimetric Froude number (Fr) is predicted using ELM and the results are compared to those obtained using a Support Vector Machines (SVM). The comparison of the ELM and SVM methods indicates a good performance for both methods in the prediction of Fr. In addition to being computationally faster, the ELM method has a higher level of accuracy (R2=0.99, MAE=0.10; MAPE=2.34; RMSE=0.14; CRM=0.02) compared with the SVM approach.

Damage of the urban gas network due to an earthquake can cause much loss including fire-induced loss to infrastructure and loss due to interruption of gas service and repairing or replacing of network elements. In this paper, a new fire ignition model is proposed and applied to a conventional semi-probabilistic model for estimating various losses due to damage of an urban gas network in an earthquake with the aim of developing a reliable tool for better designation of resources. The suggested fire ignition model takes into account parameters such as density of gas, characteristics of gas dispersion in a city, distribution of power lines as sources of ignition, and wind speed. Because of several parameters involved, inevitably a logical combination of deterministic and probabilistic variables is applied in the loss estimation model. Economic impacts of spreading of fire, gas service suspension, and gas network damage are modeled within the same semi-probabilistic framework utilizing weight functions. Assessing different fire scenarios is possible in the model for loss estimation. The model is applied to selected examples of actual urban area earthquake scenarios and the results are discussed.

Present study examines turbulent structures of a rough bed open-channel flow in the context of deterministic approach. Instantaneous velocity field is measured in different hydraulic conditions using two dimensional Particle Image Velocimetry (PIV) in vertical plane and Stereoscopic PIV in horizontal plane. Different techniques and quantities such as swirl strength, two-point and cross-correlations of the swirl strength and fluctuating velocity are estimated to control formation of hairpin vortex. Our observations show in the area far above roughness elements, there is fairly a good agreement with the observations of previous studies for smooth-bed boundary flow. This consistency demonstrates that there is a similarity between outer region of the smooth and rough-bed layer flow. Moreover, some of the observations in the present study such as contourmap of instantaneous vorticity and swirling strength or observed inclination angle in contourmap of two-point correlations of the fluctuating velocity and swirl contourmap can be considered as signatures of the hairpin vortex. Given these observations, due to the lack of direct observation of the hairpin vortex and similarity of the observed features with signatures of other types of coherent structures, it is still too hard to assurly opine that in this condition, hairpin vortex is present.

With the inclusion of IP stacks in mobile computers and devices, mobility support for Internet devices is becoming more important which allows mobile devices to move from one network to another while maintaining reachability via their permanent/home IP address. In IPv6, IPsec is implemented to only secure the signaling with high complexity, while user data is unsecured. In this paper, a new security mechanism for data integrity is proposed to overcome the unprotected data obstacle in route optimization of Mobile IPv6. In addition, it provides data security and protected communication among Mobile Node (MN) and Correspondent Node (CN). This algorithm detects and prevents an attacker who intends to modify the data by using a suitable existing encryption algorithm. When an attack is detected by MN or CN, the encryption will be started, not before attack detection. It is friendlier to delay sensitive application, including real-time services like networking game, interactive multimedia, video/audio streaming, as well as other services for data transmission which require low latency. In addition, enhanced security and handover schemes are applied to secure micro-mobility movement and reduce the handover delay and packet loss.

Key Performance Indicator (KPI) is a type of performance measurement that evaluates the success of an organization or a partial activity in which it engages. If during the running process instance the monitoring results show that the KPIs do not reach their target values, then the influential factors should be identified, and the appropriate adaptation strategies should be performed to prevent KPIs violations. In this paper, we propose an integrated monitoring, analysis, prediction and adaptation approach to prevent KPIs violations. We have considered more than one KPI for a specific process and have tried to reach their target values simultaneously by proactive runtime adaptation before the end of the running process. In order to identify the dependency between KPIs and lower-level influential factors, an analysis is done on the data collected from historical process executions. For this purpose, Data Mining techniques have been used. The result is used to predict the KPIs values of the running instance. If KPIs violations are detected, adaptation requirements and adaptation strategies are identified. Since it is possible to define several KPIs for one process, and each has its own importance, so in this paper we tried to satisfy several KPIs target values.

Web Service Choreography Description Language (WS-CDL) describes and orchestrates the services interactions among multiple participants. WS-CDL verification is essential since the interactions would lead to mismatches. Existing works verify the messages ordering, the flow of messages, and the expected results from collaborations. In this paper, we present a Z specification of WS-CDL. Besides verifying the mentioned concerns, we find out whether the choreographies are realizable by web services protocols at orchestration level. In this regard we detect the interactions between each two distinct participants which lead to deadlock or unspecified reception. An ‘itinerary purchase’ case study for prototyping the transformation rules is presented and the Z/EVES tool is used to demonstrate the protocol compatibility. Also, we define multiple attributes to compare the choreography description languages/models from the verification and adaptation viewpoints.

Prediction of traffic is very crucial for its management. Because of human involvement in the generation of this phenomenon, traffic signal is normally accompanied by noise and high levels of non-stationarity. Therefore, traffic signal prediction as one of the important subjects of study has attracted researchers’ interests. In this study, a combinatorial approach is proposed for traffic signal prediction, based on Neural Networks and Particle Swarm Optimization algorithm. Elman Neural Network is chosen from amongst many types of Neural Networks due to its feedbacked structure. To this purpose, Particle Swarm optimization algorithm is utilized for adequate training of the Neural Network, instead of common gradient descent based methods. In this work, wavelet transform is employed as a part of the preprocessing stage, for the elimination of transient phenomena as well as for more efficient training of the Neural Network. Simulations are carried out to verify performance of the proposed method, and the results demonstrate good performance in comparison to other methods.

In this paper, a novel method based on a combination of Extended Kalman Filter (EKF) with Self-adaptive Differential Evolution (SaDE) algorithm to estimate rotor position, speed and machine states for a Permanent Magnet Synchronous Motor (PMSM) is proposed. In the proposed method, as a first step SaDE algorithm is used to tune the noise covariance matrices of state noise and measurement noise in off-line. In the second step, the optimized values of above covariance matrices are injected into EKF in order to estimate the rotor speed on-line. The estimated speed is fed back to the PI controller and to minimize the speed error, parameters of PI controller are tuned again using SaDE algorithm. The simulation results show that the tuned covariance matrices Q and R improve convergence of estimation process, quality of estimated states and PI controller improves the settling time and stability of the system.

This paper presents a new observer based fuzzy terminal sliding mode controller design for a class of fractional order nonlinear systems. Robustness against uncertainty and disturbance, the stability of the close loop system and the convergence of both the tracking and observer errors to zero are the merits of the proposed the observer and the controller. The high gain observer is applied to estimate the state variables of the system. The fuzzy system is applied to decrease chattering of the controller. Finally, numerical simulation on a chaotic system demonstrates the powerful and effectiveness of the proposed method.

Docolorization of Methylene Blue was investigating using a Ultrasonic/Fenton like reactor in batch mode. The effects of pH, reaction time, initial concentration of dye, H2O2 and Fe on the dye removal was studied. It was found that the increase of initial dye and H2O2 concentration and the increase of initial pH, are not beneficial for improving the dye removal efficiency. Increasing the dye concentrations from 50 to 400 mg/L resulted in decreasing the rate of decolorization from 0.255 to 0.063 min-1, respectively. Complete removal (100%) was observed, when pH, reaction time, initial concentration of dye, H2O2, Fe and ultrasound density were found to be 3, 30 min, 100 mg/L, 200 mg/L, 25 mg/L, 40 kHz, respectively. The results showed that H2O2/Fe° equal 8 is more effective for dye removal.

The adsorption of Fe2 by the manganese oxide coated zeolite (MOCZ) and iron oxide coated zeolite (FOCZ) was studied. Surface properties of adsorbents have been investigated for monitoring their changes and morphology for both of the MOCZ and FOCZ. Main variables namely; contact time, pH, initial concentration of Fe2, size and dosage of adsorbent have been optimized, and the results contrasted with isotherm and kinetic models for finding best fit. The best fit of the adsorption isotherms was obtained using the Langmuir model (R2=0.96 and 0.92) using MOCZ and FOCZ. The rates of adsorption were found to conform to the pseudo-second-order kinetic with a good correlation (R2=0.98 and 0.82 for MOCZ and FOCZ, respectively). The results indicated that MOCZ has good ability (80% removal of Fe2) for the removal of Fe from water. The MOCZ exhibited the porous structure with high surface area rather than FOCZ, and the percentage removal of Fe2 by MOCZ was better than FOCZ.

In order to reduce costs and increase efficiency of a supply chain system, cross docking is one of the most important strategies of warehousing for consolidation shipments from different suppliers to different customers. Products are collected from suppliers by inbound trucks and then moved to customers by outbound trucks through cross dock. Scheduling of trucks plays important role in the cross docking system. In this paper, we consider a single cross dock multi-product with multiple dock doors which sequence of products and trucks scheduling are specified simultaneously. Also, we have considered multiple temporary storages with different capacities and equipmentæ each of which is used for a specific set of products. These products are perishable; so, avoiding from storage is necessary. A two- level optimization model for this problem is proposed. The first level includes scheduling of inbound and outbound trucks aim to minimizing makespan and second level is maximizing direct shipment in order to reduce the level of storage. The problem is mathematically formulated by a mixed integer, nonlinear programming (MINLP). A real data set is used to solve the model and results confirm better efficiency and less storage.

In this article, the failure of a heat exchanger during its operation in the marine environment has been analyzed. This heat exchanger was used for cooling the oil in a marine diesel engine. Based on the existing failure history, damages in engine components were observed after 89 hours of engine working due to the leakage of the sea water to the oil. For the objective of the failure analysis, each component was investigated under the stereo optical microscopy and the scanning electron microscopy (SEM). The diameter of pits was also recorded as 8 micrometer. Besides, the chemical composition of corrosion products on the surface and in pits was additionally analyzed with the energy dispersive X-ray spectroscopy (EDAX). Results indicated that two corrosion mechanisms were failure root causes of leakages, including the crevice corrosion and the pitting corrosion. In such situation, in the engine, the oil and the sea water in tubes of the heat exchanger mixed and decreased the oil viscosity and damaged the oil film on crankshaft bearings, and finally caused damages of the engine.

For a long period of time, design and manufacturing technology of high flow rated vertically suspended pumps (VSPs) which have an extensive applications in many industries such as water and wastewater, mining, petrochemical and oil and gas industries, used to be imported from European countries. For the first time in Iran's pump industry, with the support of Ministry of Petrochemical[ah1] and great effort of Iranian experts, VS1-1200.1300 API pump with a flow rate of 10330 m3/h was designed, manufactured and tested successfully. This pump is now installed in Persian Gulf Star Oil Refinery. The main purpose of this research is computational fluid dynamic (CFD) analysis of VS1-1200.1300 pump. Based on the requirement, hydraulic profile of impeller and diffuser blades were extracted from CFTurbo software, 3D mechanical model designed in Catia software and CFD analysis carried out using ANSYS-FLUENT software based on realizable k-e turbulent model and SIMPLEC algorithm for different flow rates. Experimental performance tests were carried out on manufactured VS1 pump for 6 different flow rates and the results were compared with numerical ones. The outcomes illustrated good agreement of experimental and numerical data even in high flow rates which expand the understanding of the flow in this type of pump, guide design optimizations and provide a basis to investigate flow in more vertical pumps.

In this work, a multi-objective optimization on novel insulated roof with solar water heating system at low material cost has been carried out through Taguchi based grey relational analysis technique. The novel roofs have concrete, insulating polyurethane, and a channel of water in a metallic pipe tunneling the chromium block. Chromium block is used to conduct more heat to raise the water to relatively high temperature. On the other hand, roof with such high conductive material gains more indoor heat and this can be reduced by providing insulation material at the bottom of the roof. Performance of such a novel roof on water heating and heat insulation have been studied and provided for the months of December and May. In this multi-objective optimization study, chromium block thickness, polyurethane layer thickness, pipe material and pipe diameter are considered as control parameters and varied for three levels. Taguchi’s L9 orthogonal array has been employed and the performance of novel roof patterns is studied through numerical simulation. The optimized novel roof raises the water temperature by 44°C in December and maintains the room temperature at 28°C in the month of May which is 3°C less than the conventional roof. Finally, ANOVA is employed to identify the contribution of each control parameter on overall multiple objective function.

Vertical silos are large cylinders used for material storage in agriculture and mineral industries. One of the silo problems is its obstruction due to dome and dense packing. Depend on the material properties and silo dimensions several techniques are used to solve this problem. In the present work, possibility of obstruction solution of a laboratory silo by ball impact is investigated. Test materials are magnetite and hematite concentrate and reproducible hematite, having specified wet. Ball impacts fracture the bulk and make it to flow. The profile of fractured regime is captured and the required number of impacts which provide the continuous flow are registered. Results show that different materials do not have the identical behavior during ball impacts. Moreover, it has been revealed that as the wet increases, the obstruction intensity increases and more impacts are required. Results will be used to optimum impactor be designed for obstruction solution of operating silos in Gol-e-Gohar iron ore complex.