International Journal of Engineering
Volume:33 Issue: 1, Jan 2020

The potential utilization of encapsulation techniques in food, pharmaceutical and agricultural products preparation, presents a new alternative for complementary technologies such as targeting delivery vehicles and carriers for active food ingredients. Encapsulation could be accomplished by different techniques like: simple or complex coacervation, emulsification technique, phase separation, spray drying, spray chilling or spray cooling, extrusion coating, freeze drying, fluidized-bed coating, liposomal entrapment, centrifugal suspension separation, co-crystallization and molecular inclusion complexation. Encapsulation is a method by which one bioactive material or mixture of materials is coated by the other material. It is designed for protection, isolation, assists in the storage and controlled release. A timely and targeted release improves the effectiveness of ingredients, broadens the application and ensures optimal dosage, thereby improving cost-effectiveness process for manufacturers. This review highlights recent innovations in encapsulation and controlled release technologies. In addition, design principle of novel peppermint oil delivery systems which displays the new structured biomaterials for capsules fabrication by complex coacervation technique, besides microemulsification method for bioactive material, Lactobacillus encapsulation and targeted release studies reported.

Quercetin is a biological flavonoid, which can be found in red kidney bean at high concentration. In this study, a comparison was conducted between traditional and modern extraction methods. Sequential microwave-assisted extraction was used for isolation of quercetin from red kidney bean. The effect of several factors such as particle size of grinded kidney bean, extraction solvent, microwave power and extraction time on the extraction yield of quercetin was considered. To analyze the quercetin, HPLC method was developed. The highest extraction efficiency was obtained (35.8 mg quercetin /g kidney bean) when 60 w/w% acetone used as the solvent. In addition, the solvent to solid ratio was 10:1 and the irradiation power of 800W was applied for the experiment duration of 1 min. Acquired extraction yield according to the current method was higher than extracted quercetin from soxhlet (24.6 mg quercetin /g kidney bean) and maceration (32.75 mg quercetin /g kidney bean). In the present study, quercetin was successfully extracted from kidney bean by microwave-assisted extraction. Quercetin structure remains intact and can be used to produce therapeutic compounds.

The magnetite (Fe3O4) nanoparticle and graphene oxide (GO) have  become interesting materials due to their advanced applications. In this work, we investigated the fabrication of Fe3O4 nanoparticles (NPs) from iron sands and reduced graphene oxide (rGO) NPs from natural graphite. The core-shell fabrication of the Fe3O4/rGO was conducted by means of ex-situ method using ethanol as the medium. The crystal structure of Fe3O4/rGO was observed using X-ray diffraction (XRD) and functional groups were examined using Fourier transform infra-red (FTIR) spectroscopy. The characteristic of the disturbance originated by carbon atoms was investigated by Raman spectroscopy. The morphological, particle sizes and formation studied with transmission electron microscopy (TEM). The magnetic properties were analyzed using vibrating sample magnetometer (VSM). Furthermore, analysis of the adsorption performance, namely: dye-removal efficiency (DRE) and degradation rate (DR), as candidate materials absorbent were performed by means of UV-Vis spectroscopy. The data analysis of structure and phase of Fe3O4/rGO presented cubic spinel structure with crystallite size of 26-38 nm. The functional group analysis presented the existence of C-OH, C=O, C-O, and Fe-O. The micrograph analysis from the TEM image showed the particle size of the sample was in the range of 10 - 30 nm. Along with the thickening shell, the saturation magnetization of Fe3O4/rGO decreased from 22.60 to 18.48 emu/g and decreased from 29.21 to 10.45 emu/g for Fe3O4. Finally, the rGO composition affects the shell wall, which encloses Fe3O4 as the core. Interestingly, an increase in absorption characteristic of natural dyes Fe3O4/rGO enhanced by the decrease of the shell thickness.

In this study, some parameters such as quenching and boiling curves of a stainless steel cylindrical rod 80 mm long and having a diameter of 15 mm were experimentally obtained in saturate pure water and two nanofluids (SiO2 and TiO2) with 0.01 wt%. The cylinder was vertically lowered into the pool of saturated water and its temporal center temperature was measured by a thermocouple. The boiling curves were then obtained by solving a transient one-dimensional inverse heat conduction model and measuring the temperature at the center of the cylinder. The images of the surface morphology and uniformity of the deposited SiO2 and TiO2 nano particles were captured by the scanning electron microscope (SEM). The cooling time during quenching of the cylinder was decreased about 50% by nanoparticles deposition. However, the SiO2 and TiO2 nano particle deposition have similar critical heat flux increment (up to 120%). Film boiling heat transfer rate increased by repetitive quenching in SiO2 nanofluid.

In many studies, the alternative load path method (APM) has been used for progressive collapse analysis. In this method, one or several columns of the building are removed and the building response is investigated. This method ignores the initial local failure cause of building and this can affect the structural response. Investigation of ignoring the initial local failure cause of steel braced frames is the main purpose of this research. The variables include the type of progressive collapse investigation (ignoring the initial cause of failure or APM, considering blast loading and the heat caused by the fire as the initial causes of failure) and the location of the initial local failure in plan (outer and inner frame) and in floors (1st, 2nd and 3rd). 4-story braced steel buildings were simulated using ABAQUS software and the responses were compared using different methods. The most important results showed that the axial forces are very noticeable in the columns around the damaged site if the initial local failure caused by explosive loading; while these forces are ignored when APM is used. Therefore, due to this significant difference, if the design of a steel building is to be considered against progressive collapse, it is recommended to consider the initial local failure in order to make the appropriate design in accordance with it. Therefore, the initial loading type has a very significant effect on the structure response, and ignoring the initial local failure can lead to incorrect predictions of the structure response.

In this paper, modified solutions were compared through utilizing three different approximate methods for bar structures. The modifications considered various changes in the initial design. To authors' best of knowledge, the studies have carried out on this matter so far are not broad enough and have considerred the simeltaneous variations of size, geometry and topology on the bar structures. In this study, three well-known methods, including combined approximation, rational approximation and the approximate inversion of stiffness matrix methods are formulated. A large variety of problems will be performed with different characteristics to compare the ability of these approaches in determining the suitable approximate modified displacements. Cross sectional properties and nodal coordinates are considered as design variables. Displacement errors and computational efforts of the processes considered as comparison factors. It is shown that the approximate inversion of the stiffness matrix method cannot solve the problems, which requires the modification of structural geometry. Furthermore, the combined approximation and rational approximation methods have the ability of reaching displacements with suitable quality in the problems with a moderate size.

In this study, the performance of triangular added damping and stiffness (TADAS) dampers combined with curved dampers (Curved-TADAS damper) is evaluated in moment resisting steel frame (MRSF). These dampers are passive and install in the beam-column connection region. Variable parameters of this study involve the width of curved damper (50, 75 and 100 mm), the thickness of TADAS damper (5 and 10 mm) and the number of TADAS damper (2, 4 and 6). Evaluation of MRSF was performed using the finite element method by ABAQUS. Two different experimental studies were used in order to evaluate the validity of the numerical simulation method and a suitable agreement was obtained. The response of the frames in different modes was compared with parameters such as energy dissipation, strength, stiffness, hysteresis damping ratio, and ductility. In the end, the performance of the proposed dampers was compared with the curved damper. The results show that Curved-TADAS dampers reduce the structural responses to seismic loading and prevent structural failure due to the dissipation of a large amount of seismic input energy. The function of these systems is such that, by performing special deformations, they absorb and deplete a large amount of earthquake input energy of the structure.

A reliable speech enhancement method is important for speech applications as a pre-processing step to improve their overall performance. In this paper, we propose a novel frequency domain method for single channel speech enhancement. Conventional frequency domain methods usually neglect the correlation between neighboring time-frequency components of the signals. In the proposed method, we take this correlation into account via: 1) considering neighboring correlation for speech signals, we break down the clean speech into two uncorrelated components; 2) considering neighboring correlation for noise, we approximate the noise as a rank-1 component. Then, we design a linearly constrained minimum variance (LCMV) filter which aims at removing the dominant part of the noise, while keeping the speech signal undistorted. Performance of the proposed method is evaluated in terms of output signal to noise ratio (SNR) and speech distortion index under various noise environments. Evaluation results demonstrate that our method yields higher noise reduction and lower speech distortion compared to some recent methods.

Evaluating the reliability of loosely coupled Software as a Service through the paradigm of a cluster-based and non-cluster-based web server is considered to be an important attribute for the service delivery and execution. We proposed a novel method for measuring the reliability of Software as a Service execution through load testing. The fault count of the model against the stresses of users is deployed. A prototype application using Simple Object Access Protocol-based web service is developed and the study is carried out over there. The experimental setup, architecture, load testing results followed by a comparative study is discussed in this work. It is observed that the reliability of the service by using clustered and non-clustered web server degrades after a specific limit of stress level execution point. The comparative assessment predicts that the reliability of service by using a cluster-based web server is better than the service with a non-cluster based web server. With an increase in the stress level of usage in a multi-tenant environment, the service with clustered web server delivers better reliability than the service without a clustered web server. The occurrences of HyperText Transfer Protocol request failure in the service with a clustered web server is comparatively less than its counterpart service without a clustered web server. The study helps in identifying the applicability of the method and shows the effectiveness of such deployment.

Islanding operation is one of the main features of a MicroGrid (MG), which is realized regarding the presence of distributed energy resources (DERs). However, in order to deal with the control challenges, which an MG faces during island operation, particularly when the transition is associated with certain excessive load, an efficient control strategy is required. This paper introduces a Central Management Agent (CMA) which maintains the stability of the MG, once it is islanded, by controlling an Energy Storage System (ESS) and a Central Synchronous Generator (CSG). Further, this paper proposes a new adaptive load-shedding/restoration schemes that calculates the amount of power imbalance based on frequency measurements combined with the mean value of the frequency gradient. The primacy of the proposed scheme over existing schemes, like instantaneous frequency gradient-based load shedding scheme, is its robustness against frequency oscillations. Moreover, the proposed method acts compatible with the control routine of DERs and the intermittent nature of the PV plant. As another salient feature of this paper, a Hardware In the Loop (HIL) testbed for real-time simulation is developed under which the proposed scheme and related communication with CMA along with other components are evaluated. The obtained results show that the control strategy can confidently conserve the stability of the MG in islanded mode and meet smooth reconnection to the grid-connected mode.

Nowadays, optimal integration and utilization of renewable energy sources (RES) are of the most challenging issues in power systems. The wind and solar generation units' maximum production may or may not occur at peak consumption times resulting in non-optimal utilization of these resources. As a solution to this problem, energy storage systems (ESS) are embedded in networks. However, the power transfer from RES to ESS may lead to network congestion. In this paper, the simultaneous application of dynamic thermal rating (DTR) technology and ESS devices is proposed. The DTR is used to overcome the problem of transmission lines limited capacity and ESS is responsible for mitigating curtailment of RESs energy production by saving their generated energy in non-peak hours. The RESs generation and lines’ ratings are calculated based on hourly actual weather elements. For evaluating the proposed method, a linearized formulation of DC-OPF is used in the problem definition and also simulated on a modified IEEE 30-bus test system including a wind farm, solar park, and ESS devices by using MATLAB software. In addition, different comparisons are performed demonstrating the remarkable and better performance of the proposed method compared to previously introduced methods.

This article presents a new feature extraction technique based on the temporal tracking of clusters in spectro-temporal features space. In the proposed method, auditory cortical outputs were clustered. The attributes of speech clusters were extracted as secondary features. However, the shape and position of speech clusters change during the time. The clusters temporally tracked and temporal tracking parameters were considered in secondary features. The new architecture was proposed for phoneme classification by a combining classifier using both tracked and energy-based features. Clustered based spectro-temporal features vectors were used for the classification of several subsets of TIMIT database phonemes. The results show that the phoneme classification rate was improved Using tracked spectro-temporal features. The results were improved to 78.9% on voiced plosives classification which was relatively 3.3% higher than the results of non-tracked spectro-temporal feature vectors. The results on other subsets of phonemes showed good improvement in classification rate too.

The purpose of this paper was to design a conceptual model of sustainable outsourcingwith a balanced scorecard using the hierarchical analysis process. In this research, success factors of outsourcing were identified based on previous studies conducted inside and outside of the country. To ensure the validity of the factors, in addition to the content validity and the validity index, the reliability was guaranteed using the inconsistencyratio of the paired comparison questionnaire based on the Expert Choice report. An affinity diagram developed using the brainstorming approach was implemented for strategic objectives of the model. Our findings indicated that a sustainable outsourcing model was successfully designed using a balanced scorecard. Economic, social and environmental sustainability was considered in each of the balanced scorecard faces used in the model. In this work, sustainable domestic business, customer satisfaction, and sustainable learning and growth were the main objectives. Finally, a balanced scorecard with 26 strategic objectives was designed and implemented. To this end, paired comparisons were performed to compute the importance of each strategic goal in every phase and make prioritization accordingly.

This article explores the development of previous models to determine hubs in a competitive environment. In this paper, by comparing parameters of the ticket price, travel time and the service quality of hub airports, airline hubs are divided into six categories. The degree of importance of travel time and travel cost are determined by a multivariate Lagrange interpolation method, which can play an important role in allocating travelers to follower airline hubs. Then, based on the seasonal demand of travelers, we consider travel demand as uncertain parameters. To determine the robust counterpart of this category of hub location models, a robust optimization method is used. Finally, models are tested in a case study. The central results show that the follower airline's income has a considerable growth and can absorb nearly 2% of travelers of the leader airline due to lower travel costs and travel time compared to that of leader airline.

The purpose of this study was to fabricate and investigate the highly porous structure using titanium dioxide, which is a candidate for bone defect repairing. For this purpose, TiO2 scaffolds were synthesized using titanium butoxide, Pluronic F127 surfactant, and polyurethane foam blocks. Therefore, a colloid includes titanium butoxide and F127 and the polyurethane foams were immersed in it. The samples were annealed at different temperatures in the range of 500 to 600 ° C. The results of simultaneous thermal analysis (STA) test showed that volatile materials left the system completely when the temperature reached 550 ºC. Also small angle X-ray scattering (SAXS) test revealed that these scaffolds composed of highly ordered mesoporous structures. The obtained scaffolds at 550 ºC had specific surface area of 85.736 m2g-1with the mean mesopore size of 7.0498 nm and macroporosity in the range of 100 to 350 μm. The presence of mesopores and their distribution were investigated with transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS). The base scaffold was then immersed in a simulated body solution for 3,7and 14 days and analyzed by scanning electron microscopy (SEM) and energy-dispersive X-ray. The results show its ability for apatite formation.

Friction stir welding is a relatively new solid state joining process, which is suitable for welding similar and dissimilar materials.  The present research work concentrates on the effect of tool rotational speed on the tensile, microstructural properties and microhardness of the friction stir welded joints of different grades of austenitic stainless steel sheets. Four different tool rotational speeds are used in the experimentation while the other process parameters like traversing speed and the tool tilt angle are kept constant. The tensile testing, micrography and microhardness measurements were carried out in the welded samples. It is observed from the results of tensile testing that the joint made at the tool rotational speed of 1320 rpm has the maximum strength among the experimented speeds. The measured microhardness values at heat affected zone and parent metal zone have shown higher hardness than the weld zone. Fine and equi-axed grains are observed in the welded region at all experimented speeds with a negligible amount of transformation of austenite into martensite. These results have impact on the development of welding procedure for dissimilar stainless steel friction stir welding process.

In the present research, the effects of spot-welding process parameters on the nugget diameter and electrode penetration depth of spot-welded joints were investigated. To achieve this, a spot-welded joint of three-thin sheet low carbon steels (same thicknesses of 0.8 mm) was simulated as an electerical-thermal-mechanical coupling of 3D finite element model. After validating the finite element simulation presented in this study by comparison with the experimental results for the spot diameter, various cases of spot welds were analyzed based on the design on experiment (i.e., Taguchi method). Six variables including electrode force, electric current, and quadrilateral times (squeeze, up-slope, welding time, and hold) at three different levels were considered as Taguchi algorithm inputs. The results of Taguchi sensitivity analysis showed that the parameters of electrical current (22 %) and welding time (17 %) are the most effective factors on the nugget diameter. Next, Multiple Regression Technique (MRT) was used to present a new equation for calculating spot diameter via the process parameters. The findings of this study showed that the difference between FE results and MRT for predicting spot diameter is less than 13%. Eventually, Response Surface Method (RSM) was utilized to determine the interaction effects of process parameters on the spot weld quality.

A new characteristic-based method is developed and used for solving the mixed and forced convection problems. The nano-fluid flow with heat transfer is simulated with a novel characteristic-based scheme in closed domains with different aspect ratios. For this purpose, a FORTRAN code has been written and developed. Water as a pure fluid and water-titanium dioxide as a nano-fluid were considered. The governing equations are solved by the finite volume utilizing a characteristic-based scheme for the convective fluxes. The simulation is done at Grashof numbers from 100 to 104, Reynolds numbers from 100 to 1000, and volume fractions of nano-particles from 0% to 10%. Streamlines, isotherms, friction factor, and mean Nusselt number are obtained in various conditions. The convective behavior of nano-fluid is explored as a function of several parameters, such as Grashof number and geometrical parameters. Results indicate that the mean Nusselt number for the nanofluid is up to 23% more than that of pure water.

Operation Theatre (OT) is the most important area where precise controlled on indoor air quality is required because it is directly related to patient health and its recovery period. This work aims to study and visualize the airflow distribution of conventional flat air diffuser ventilation system and newly designed angular air ventilation system in OT. Angular Air Distribution (AAD) system is designed in such way that, conditioned air is throw in OT with some angle so it can cover the maximum area of OT with laminar flow and minimum installation area.  The performance of angular air distribution (AAD) system with varying inlet diffuser angle, constant 0.4m/s  inlet velocity and air flow pattern are investigated with the help of numerical simulation and experimental setup of prototype OT model. Detail experimental investigation  is done on a prototype with the help of a smoke test and camera target method (CTM). Both numerical and experimental results showed a similar pattern of air distribution for the various design configurations.

Nowadays, shovels play an important role in production of open pit mines and their failures result in significant production loss and considerable increase in maintenance costs. Therefore, reliability and risk analysis can help to improve production, productivity and reduce production costs. In this study, reliability of electric cable shovel of Chadormalu iron ore mine in Iran was investigated. Failure distribution function of the subsystems whose failure information is available was provided by statistical analysis using EasyFit 5.5, Minitab 18 and the subsystems with low or unavailable failure information which was generated by experts using normal distribution function. Criticality of subsystems was determined using Birnbaum and Fussell–Vesely importance measures reliability. Results showed that reliability of cable shovel has reached to zero after 40 hours and subsystems of crowd gearbox, swing gearbox, lubrication and bucket door are the most critical subsystems.