http://www.hindawi.com The latest articles from Hindawi Publishing Corporation © 2013 , Hindawi Publishing Corporation . All rights reserved. Thu, 11 Apr 2013 13:31:39 +0000 http://www.hindawi.com/journals/mse/2013/730456/ Proper control of distillation columns requires estimating some key variables that are challenging to measure online (such as compositions), which are usually estimated using inferential models. Commonly used inferential models include latent variable regression (LVR) techniques, such as principal component regression (PCR), partial least squares (PLS), and regularized canonical correlation analysis (RCCA). Unfortunately, measured practical data are usually contaminated with errors, which degrade the prediction abilities of inferential models. Therefore, noisy measurements need to be filtered to enhance the prediction accuracy of these models. Multiscale filtering has been shown to be a powerful feature extraction tool. In this work, the advantages of multiscale filtering are utilized to enhance the prediction accuracy of LVR models by developing an integrated multiscale LVR (IMSLVR) modeling algorithm that integrates modeling and feature extraction. The idea behind the IMSLVR modeling algorithm is to filter the process data at different decomposition levels, model the filtered data from each level, and then select the LVR model that optimizes a model selection criterion. The performance of the developed IMSLVR algorithm is illustrated using three examples, one using synthetic data, one using simulated distillation column data, and one using experimental packed bed distillation column data. All examples clearly demonstrate the effectiveness of the IMSLVR algorithm over the conventional methods. Muddu Madakyaru, Mohamed N. Nounou, and Hazem N. Nounou Copyright © 2013 Muddu Madakyaru et al. All rights reserved. Thu, 21 Mar 2013 15:48:23 +0000 http://www.hindawi.com/journals/mse/2013/475478/ Computer-aided modeling and simulation are a crucial step in developing, integrating, and optimizing unit operations and subsequently the entire processes in the chemical/pharmaceutical industry. This study details two methods of reducing the computational time to solve complex process models, namely, the population balance model which given the source terms can be very computationally intensive. Population balance models are also widely used to describe the time evolutions and distributions of many particulate processes, and its efficient and quick simulation would be very beneficial. The first method illustrates utilization of MATLAB's Parallel Computing Toolbox (PCT) and the second method makes use of another toolbox, JACKET, to speed up computations on the CPU and GPU, respectively. Results indicate significant reduction in computational time for the same accuracy using multicore CPUs. Many-core platforms such as GPUs are also promising towards computational time reduction for larger problems despite the limitations of lower clock speed and device memory. This lends credence to the use of highfidelity models (in place of reduced order models) for control and optimization of particulate processes. Anuj V. Prakash, Anwesha Chaudhury, and Rohit Ramachandran Copyright © 2013 Anuj V. Prakash et al. All rights reserved. Mon, 11 Mar 2013 08:24:24 +0000 http://www.hindawi.com/journals/mse/2013/815158/ We used a physically motivated internal state variable plasticity/damage model containing a mathematical length scale to idealize the material response in finite element simulations of a large-scale boundary value problem. The problem consists of a moving striker colliding against a stationary hazmat tank car. The motivations are (1) to reproduce with high fidelity finite deformation and temperature histories, damage, and high rate phenomena that may arise during the impact accident and (2) to address the material postbifurcation regime pathological mesh size issues. We introduce the mathematical length scale in the model by adopting a nonlocal evolution equation for the damage, as suggested by Pijaudier-Cabot and Bazant in the context of concrete. We implement this evolution equation into existing finite element subroutines of the plasticity/failure model. The results of the simulations, carried out with the aid of Abaqus/Explicit finite element code, show that the material model, accounting for temperature histories and nonlocal damage effects, satisfactorily predicts the damage progression during the tank car impact accident and significantly reduces the pathological mesh size effects. Fazle R. Ahad, Koffi Enakoutsa, Kiran N. Solanki, Yustianto Tjiptowidjojo, and Douglas J. Bammann Copyright © 2013 Fazle R. Ahad et al. All rights reserved. Thu, 07 Feb 2013 14:45:12 +0000 http://www.hindawi.com/journals/mse/2013/142165/ Modeling the multiagents cooperative systems inspired from biological self-organized systems in the context of swarm model has been under great considerations especially in the field of the cooperation of multi robots. These models are trying to optimize the behavior of artificial multiagent systems by introducing a consensus, which is a mathematical model between the agents as an intelligence property for each member of the swarm set. The application of this novel approach in the modeling of nonintelligent multi agents systems in the field of cohesion and cluster formation of nanoparticles in nanofluids has been investigated in this study. This goal can be obtained by applying the basic swarm model for agents that are more mechanistic by considering their physical properties such as their mass, diameter, as well as the physical properties of the flow. Clustering in nanofluids is one of the major issues in the study of its effects on heat transfer. Study of the cluster formation dynamics in nanofluids using the swarm model can be useful in controlling the size and formation time of the clusters as well as designing appropriate microchannels, which the nanoparticles are plunged into. Mohammad Pirani, Hassan Basirat Tabrizi, and Ali Farshad Copyright © 2013 Mohammad Pirani et al. All rights reserved. Mon, 14 Jan 2013 13:57:38 +0000 http://www.hindawi.com/journals/mse/2013/694354/ A parallel adaptive pseudo transient Newton-Krylov-Schwarz (NKS) method for the solution of compressible flows is presented. Multidimensional upwind residual distribution schemes are used for space discretisation, while an implicit time-marching scheme is employed for the discretisation of the (pseudo)time derivative. The linear system arising from the Newton method applied to the resulting nonlinear system is solved by the means of Krylov iterations with Schwarz-type preconditioners. A scalable and efficient data structure for the NKS procedure is presented. The main computational kernels are considered, and an extensive analysis is reported to compare the Krylov accelerators, the preconditioning techniques. Results, obtained on a distributed memory computer, are presented for 2D and 3D problems of aeronautical interest on unstructured grids. Marzio Sala, Pénélope Leyland, and Angelo Casagrande Copyright © 2013 Marzio Sala et al. All rights reserved. Wed, 26 Dec 2012 15:40:02 +0000 http://www.hindawi.com/journals/mse/2012/793462/ Liquid cooling electronics using microchannels integrated in the chips is an attractive alternative to bulky aluminum heat sinks. Cooling can be further enhanced using nanofluids. The goals of this study are to evaluate heat transfer in a nanofluid heat sink with developing laminar flow forced convection, taking into account the pumping power penalty. The proposed model uses semi-empirical correlations to calculate effective nanofluid thermophysical properties, which are then incorporated into heat transfer and friction factor correlations in literature for single-phase flows. The model predicts the thermal resistance and pumping power as a function of four design variables that include the channel diameter, velocity, number of channels, and nanoparticle fraction. The parameters are optimized with minimum thermal resistance as the objective function and fixed specified value of pumping power as the constraint. For a given value of pumping power, the benefit of nanoparticle addition is evaluated by independently optimizing the heat sink, first with nanofluid and then with water. Comparing the minimized thermal resistances revealed only a small benefit since nanoparticle addition increases the pumping power that can alternately be diverted towards an increased velocity in a pure water heat sink. The benefit further diminishes with increase in available pumping power. Manu Mital Copyright © 2012 Manu Mital. All rights reserved. Tue, 25 Dec 2012 12:30:58 +0000 http://www.hindawi.com/journals/mse/2012/160297/ Matthias Pätzold, Neji Youssef, and Carlos A. Gutierrez Copyright © 2012 Matthias Pätzold et al. All rights reserved. Mon, 24 Dec 2012 16:23:28 +0000 http://www.hindawi.com/journals/mse/2012/867820/ A detailed CFD modelling of an open refrigerated display cabinet has been formulated in a previous study. Some modifications are introduced in order to perform parametric studies dealing with low-cost geometrical and functional characteristics for improvement of the global performance and energy efficiency. The parametric studies are devoted to the analysis of the thermal response and behaviour inside the food conservation space influenced by (1) air flow rate through the evaporator heat exchanger; (2) air curtain behaviour; (3) hole dimensions and distribution of the back panel; (4) discharge and return grilles angles; and (5) flow deflectors inside the internal duct. The analysis of the numerical predictions from the parametric studies allows the development of an optimized model for the conception of an open refrigerated display cabinet with a more adequate configuration. The numerical predictions of the optimized model show lower product temperature and reduced electrical energy consumption, allowing the improvement of the food safety and the energy rationalization of the refrigeration equipment. Pedro Dinis Gaspar, L. C. Carrilho Gonçalves, and R. A. Pitarma Copyright © 2012 Pedro Dinis Gaspar et al. All rights reserved. Thu, 20 Dec 2012 18:34:11 +0000 http://www.hindawi.com/journals/mse/2012/983147/ We make use of information inside infant’s cry signal in order to identify the infant’s psychological condition. Gaussian mixture models (GMMs) are applied to distinguish between healthy full-term and premature infants, and those with specific medical problems available in our cry database. Cry pattern for each pathological condition is created by using adapted boosting mixture learning (BML) method to estimate mixture model parameters. In the first experiment, test results demonstrate that the introduced adapted BML method for learning of GMMs has a better performance than conventional EM-based reestimation algorithm as a reference system in multipathological classification task. This newborn cry-based diagnostic system (NCDS) extracted Mel-frequency cepstral coefficients (MFCCs) as a feature vector for cry patterns of newborn infants. In binary classification experiment, the system discriminated a test infant’s cry signal into one of two groups, namely, healthy and pathological based on MFCCs. The binary classifier achieved a true positive rate of 80.77% and a true negative rate of 86.96% which show the ability of the system to correctly identify healthy and diseased infants, respectively. Hesam Farsaie Alaie and Chakib Tadj Copyright © 2012 Hesam Farsaie Alaie and Chakib Tadj. All rights reserved. Thu, 20 Dec 2012 18:33:40 +0000 http://www.hindawi.com/journals/mse/2012/362849/ Flickermeter is a common name for a system that measures the obnoxiousness of flicker caused by voltage fluctuations. The output of flickermeter is a value of short-term flicker severity indicator, . This paper presents the results of the numerical simulations that reconstruct the processing of flickermeter in frequency domain. With the use of standard test signals, the characteristics of flickermeter were determined for the case of amplitude modulation of input signal, frequency modulation of input signal, and for input signal with interharmonic component. For the needs of simulative research, elements of standard IEC flickermeter signal chain as well as test signal source and tools for acquisition, archiving, and presentation of the obtained results were modeled. The results were presented with a set of charts, and the specific fragments of the charts were pointed out and commented on. Some examples of the influence of input signal’s bandwidth limitation on the flickermeter measurement result were presented for the case of AM and FM modulation. In addition, the diagrams that enable the evaluation of flickermeter’s linearity were also presented. Jarosław Majchrzak and Grzegorz Wiczyński Copyright © 2012 Jarosław Majchrzak and Grzegorz Wiczyński. All rights reserved. Tue, 18 Dec 2012 08:03:46 +0000 http://www.hindawi.com/journals/mse/2012/317359/ The aim of this paper is to discuss efficient adaptive parallel solution techniques on unstructured 2D and 3D meshes. We concentrate on the aspect of parallel a posteriori mesh adaptation. One of the main advantages of unstructured grids is their capability to adapt dynamically by localised refinement and derefinement during the calculation to enhance the solution accuracy and to optimise the computational time. Grid adaption also involves optimisation of the grid quality, which will be described here for both structural and geometrical optimisation. Pénélope Leyland, Angelo Casagrande, and Yannick Savoy Copyright © 2012 Pénélope Leyland et al. All rights reserved. Mon, 17 Dec 2012 17:28:58 +0000 http://www.hindawi.com/journals/mse/2012/614070/ This study evaluates the sensitivity of microelectromechanical system (MEMS) capacitive bending strain sensor with a double layer cantilever designed to meet the requirements of spinal fusion monitoring. The cantilever structure of the sensor consists of two parallel substrate plates which constitute the electrodes, attached to an anchor made of silicon dioxide. The sensor was able to monitor bending strain value ranging from 0 to 1000 με. In order to evaluate the sensitivity of the sensor, parametric study was carried out by varying electrode gap, anchor length, and dielectric coverage between the electrodes. The nominal capacitive strain sensor for various applications has sensitivity ranging from 255 aF/με to 0.0225 pF/με. An increase in the sensitivity was observed on reducing the electrode gap and the anchor length and increasing the dielectric coverage, resulting in a highest sensitivity value of 0.2513 pF/με. It was also observed that dielectric constant has a significant effect on the sensitivity behavior of the sensor. Muhammad Irsyad Abdul Mokti and Inzarulfaisham Abd Rahim Copyright © 2012 Muhammad Irsyad Abdul Mokti and Inzarulfaisham Abd Rahim. All rights reserved. Thu, 06 Dec 2012 16:06:40 +0000 http://www.hindawi.com/journals/mse/2012/495935/ Dynamic mesh adaptation on unstructured grids, by localised refinement and derefinement, is a very efficient tool for enhancing solution accuracy and optimising computational time. One of the major drawbacks, however, resides in the projection of the new nodes created, during the refinement process, onto the boundary surfaces. This can be addressed by the introduction of a library capable of handling geometric properties given by a CAD (computer-aided design) description. This is of particular interest also to enhance the adaptation module when the mesh is being smoothed, and hence moved, to then reproject it onto the surface of the exact geometry. Angelo Casagrande, Pénélope Leyland, and Luca Formaggia Copyright © 2012 Angelo Casagrande et al. All rights reserved. Wed, 05 Dec 2012 13:43:56 +0000 http://www.hindawi.com/journals/mse/2012/264213/ We propose a wideband multiple-input multiple-output (MIMO) car-to-car (C2C) channel model based on the geometrical street scattering model. Starting from the geometrical model, a MIMO reference channel model is derived under the assumption of single-bounce scattering in line-of-sight (LOS) and non-LOS (NLOS) propagation environments. The proposed channel model assumes an infinite number of scatterers, which are uniformly distributed in two rectangular areas located on both sides of the street. Analytical solutions are presented for the space-time-frequency cross-correlation function (STF-CCF), the two-dimensional (2D) space CCF, the time-frequency CCF (TF-CCF), the temporal autocorrelation function (ACF), and the frequency correlation function (FCF). An efficient sum-of-cisoids (SOCs) channel simulator is derived from the reference model. It is shown that the temporal ACF and the FCF of the SOC channel simulator fit very well to the corresponding correlation functions of the reference model. To validate the proposed channel model, the mean Doppler shift and the Doppler spread of the reference model have been matched to real-world measurement data. The comparison results demonstrate an excellent agreement between theory and measurements, which confirms the validity of the derived reference model. The proposed geometry-based channel simulator allows us to study the effect of nearby street scatterers on the performance of C2C communication systems. Nurilla Avazov and Matthias Pätzold Copyright © 2012 Nurilla Avazov and Matthias Pätzold. All rights reserved. Tue, 04 Dec 2012 14:40:55 +0000 http://www.hindawi.com/journals/mse/2012/327901/ A transmission line model is used to design corporate-fed multilayered bow-tie antennas arrays; the simulated antennas arrays are designed to resonate at the frequencies 2.4 GHz, 5 GHz, and 8 GHz corresponding to RFID, WIFI, and radars applications. The contribution of this paper consists of modeling multilayer bow-tie antenna array fed through an aperture using transmission line model. The transmission line model is simple and precise and allows taking into account the whole geometrical, electrical, and technological characteristics of the antennas arrays. The proposed transmission line model showed its interest in the design of different multilayered bow-tie antennas and predicted the correct resonance frequency for different applications in telecommunications. To validate the proposed transmission line model, the simulation results obtained are compared with those obtained by the method of moments. The results of simulations are presented and discussed. Using this transmission line approach, the resonant frequency, input impedance, and return loss can be determined simultaneously. The paper reports several simulation results that confirm the validity of the developed model. The obtained results are then presented and discussed. S. Didouh, M. Abri, and F. T. Bendimerad Copyright © 2012 S. Didouh et al. All rights reserved. Tue, 04 Dec 2012 10:51:35 +0000 http://www.hindawi.com/journals/mse/2012/301012/ We present a new iterative method for the calculation of average bandwidth assignment to traffic flows using a WFQ scheduler in IP based NGN networks. The bandwidth assignment calculation is based on the link speed, assigned weights, arrival rate, and average packet length or input rate of the traffic flows. We prove the model outcome with examples and simulation results using NS2 simulator. Tomáš Balogh and Martin Medvecký Copyright © 2012 Tomáš Balogh and Martin Medvecký. All rights reserved. Thu, 29 Nov 2012 15:06:20 +0000 http://www.hindawi.com/journals/mse/2012/721814/ Oil and gas separators were one of the first pieces of production equipment to be used in the petroleum industry. The different stages of separation are completed using the following three principles: gravity, centrifugal force, and impingement. The sizes of the oil droplets, in the production water, are based mainly on the choke valve pressure drop. The choke valve pressure drop creates a shearing effect; this reduces the ability of the droplets to combine. One of the goals of oil separation is to reduce the shearing effect of the choke. Separators are conventionally designed based on initial flow rates; as a result, the separator is no longer able to accommodate totality of produced fluids. Changing fluid flow rates as well as emulsion viscosity effect separator design. The reduction in vessel performance results in recorded measurements that do not match actual production levels inducing doubt into any history matching process and distorting reservoir management programs. In this paper, the new model takes into account flow rates and emulsion viscosity. The generated vessel length, vessel diameter, and slenderness ratio monographs are used to select appropriate separator size based on required retention time. Model results are compared to API 12J standards. F. Boukadi, V. Singh, R. Trabelsi, F. Sebring, D. Allen, and V. Pai Copyright © 2012 F. Boukadi et al. All rights reserved. Wed, 21 Nov 2012 13:20:58 +0000 http://www.hindawi.com/journals/mse/2012/639865/ The diverging diamond interchange (DDI) can improve traffic flow by limiting the number of phases in the traffic signals and improve safety by eliminating left turns. A few instillations of these interchanges have been constructed and there is great potential to construct more. In an effort to develop a methodology to evaluate these interchanges, this paper presents the development of a discrete event simulation model of the diverging diamond interchange (DDI). Specific emphasis is on using simulation to model the DDI, a description of the operation of the simulation model, and using simulation to understand the operation of the DDI. The paper concludes that the use of the simulation package allows for rapid evaluation of the DDI and demonstrates that this interchange design will not work in all locations. Michael Anderson, Bernard Schroer, and Dietmar Moeller Copyright © 2012 Michael Anderson et al. All rights reserved. Mon, 19 Nov 2012 14:30:13 +0000 http://www.hindawi.com/journals/mse/2012/786252/ The present work aims at analysing and comparing the thermal performances of active and passive aftertreatment systems. A one-dimensional transient model has been developed in order to evaluate the heat exchange between the solid and the exhaust gas and to estimate the energy effectiveness of the apparatus. Furthermore, the effect of the engine operating conditions on the performances of emission control systems has been investigated considering standard emission test cycles. The analysis has demonstrated that the active flow control presents the higher thermal inertia and it appears more suitable to maintain the converter initial temperature level for a longer time after variations in engine load. Conversely, the traditional passive flow control is preferable when rapid “cooling” or “heating” of the solid phase is requested. Moreover, the investigation has highlighted the significant influence of the cycle time and converter length on the energetic performances of the aftertreatment apparatus. Angelo Algieri, Mario Amelio, and Pietropaolo Morrone Copyright © 2012 Angelo Algieri et al. All rights reserved. Wed, 14 Nov 2012 18:42:31 +0000 http://www.hindawi.com/journals/mse/2012/171953/ A buckling analysis has been carried out to investigate the response of laminated composite cylindrical panel with an elliptical cutout subject to axial loading. The numerical analysis was performed using the Abaqus finite-element software. The effect of the location and size of the cutout and also the composite ply angle on the buckling load of laminated composite cylindrical panel is investigated. Finally, simple equations, in the form of a buckling load reduction factor, were presented by using the least square regression method. The results give useful information into designing a laminated composite cylindrical panel, which can be used to improve the load capacity of cylindrical panels. Hamidreza Allahbakhsh and Ali Dadrasi Copyright © 2012 Hamidreza Allahbakhsh and Ali Dadrasi. All rights reserved. Wed, 14 Nov 2012 17:14:11 +0000 http://www.hindawi.com/journals/mse/2012/742786/ This paper presents an efficient electrocardiogram (ECG) signals compression technique based on QRS detection, estimation, and 2D DWT coefficients thresholding. Firstly, the original ECG signal is preprocessed by detecting QRS complex, then the difference between the preprocessed ECG signal and the estimated QRS-complex waveform is estimated. 2D approaches utilize the fact that ECG signals generally show redundancy between adjacent beats and between adjacent samples. The error signal is cut and aligned to form a 2-D matrix, then the 2-D matrix is wavelet transformed and the resulting wavelet coefficients are segmented into groups and thresholded. There are two grouping techniques proposed to segment the DWT coefficients. The threshold level of each group of coefficients is calculated based on entropy of coefficients. The resulted thresholded DWT coefficients are coded using the coding technique given in the work by (Abo-Zahhad and Rajoub, 2002). The compression algorithm is tested for 24 different records selected from the MIT-BIH Arrhythmia Database (MIT-BIH Arrhythmia Database). The experimental results show that the proposed method achieves high compression ratio with relatively low distortion and low computational complexity in comparison with other methods. Mohammed Abo-Zahhad, Sabah M. Ahmed, and Ahmed Zakaria Copyright © 2012 Mohammed Abo-Zahhad et al. All rights reserved. Sun, 11 Nov 2012 14:36:27 +0000 http://www.hindawi.com/journals/mse/2012/636135/ The method of optimization algorithms is one of the most important parameters which will strongly influence the fidelity of the solution during an aerodynamic shape optimization problem. Nowadays, various optimization methods, such as genetic algorithm (GA), simulated annealing (SA), and particle swarm optimization (PSO), are more widely employed to solve the aerodynamic shape optimization problems. In addition to the optimization method, the geometry parameterization becomes an important factor to be considered during the aerodynamic shape optimization process. The objective of this work is to introduce the knowledge of describing general airfoil geometry using twelve parameters by representing its shape as a polynomial function and coupling this approach with flow solution and optimization algorithms. An aerodynamic shape optimization problem is formulated for NACA 0012 airfoil and solved using the methods of simulated annealing and genetic algorithm for 5.0 deg angle of attack. The results show that the simulated annealing optimization scheme is more effective in finding the optimum solution among the various possible solutions. It is also found that the SA shows more exploitation characteristics as compared to the GA which is considered to be more effective explorer. R. Mukesh, K. Lingadurai, and U. Selvakumar Copyright © 2012 R. Mukesh et al. All rights reserved. Thu, 08 Nov 2012 17:30:29 +0000 http://www.hindawi.com/journals/mse/2012/756508/ A three-dimensional (3D) model for wide-band dual-polarized (DP) multiple-input-multiple-output (MIMO) mobile-to-mobile (M2M) channels is proposed. Using geometrical scattering based on concentric spheres at the transmitter (Tx) and at the receiver (Rx), a 3D parametric reference model for M2M DP multipath fading channels is developed. The channel model assumes the use of colocated half-wavelength dipole antennas for vertical and horizontal polarizations at both transmit and receive stations. Model parameters include the velocities of the Tx and Rx nodes, the distance between the nodes, the 3D antenna pattern gains, the azimuth and elevation angles of arrival and departure, the geometrical distribution of the scatterers, the Rician K-factors defining the fading envelope distributions, the maximum Doppler frequency, the scattering loss factors, the cross-polar power discrimination ratio (XPD), and the copolarization power ratio (CPR). Using the proposed model, expressions for joint time-frequency correlation functions (TFCFs) are derived which are used to investigate system behavior over different wide sense stationary uncorrelated scattering (WSSUS) channel realizations. The numerical results illustrate the sensitivities of the TFCF to simultaneous time and frequency offsets for the DP-MIMO architectures. Jun Chen and Thomas G. Pratt Copyright © 2012 Jun Chen and Thomas G. Pratt. All rights reserved. Tue, 06 Nov 2012 12:56:05 +0000 http://www.hindawi.com/journals/mse/2012/671934/ Based on global sensitivity analysis (GSA), this paper proposes a new risk assessment method for an offshore structure design. This method quantifies all the significances among random variables and their parameters at first. And by comparing the degree of importance, all minor factors would be negligible. Then, the global uncertainty analysis work would be simplified. Global uncertainty analysis (GUA) is an effective way to study the complexity and randomness of natural events. Since field measured data and statistical results often have inevitable errors and uncertainties which lead to inaccurate prediction and analysis, the risk in the design stage of offshore structures caused by uncertainties in environmental loads, sea level, and marine corrosion must be taken into account. In this paper, the multivariate compound extreme value distribution model (MCEVD) is applied to predict the extreme sea state of wave, current, and wind. The maximum structural stress and deformation of a Jacket platform are analyzed and compared with different design standards. The calculation result sufficiently demonstrates the new risk assessment method’s rationality and security. Zou Tao, Li Huajun, and Liu Defu Copyright © 2012 Zou Tao et al. All rights reserved. Wed, 31 Oct 2012 15:35:43 +0000 http://www.hindawi.com/journals/mse/2012/687961/ We present two-dimensional numerical simulations of the impact and spreading of a droplet containing a number of small particles on a flat solid surface, just after hitting the solid surface, to understand particle effects on spreading dynamics of a particle-laden droplet for the application to the industrial inkjet printing process. The Navier-Stokes equation is solved by a finite-element-based computational scheme that employs the level-set method for the accurate interface description between the drop fluid and air and a fictitious domain method for suspended particles to account for full hydrodynamic interaction. Focusing on the particle effect on droplet spreading and recoil behaviors, we report that suspended particles suppress the droplet oscillation and deformation, by investigating the drop deformations for various Reynolds numbers. This suppressed oscillatory behavior of the particulate droplet has been interpreted with the enhanced energy dissipation due to the presence of particles. Hyun Jun Jeong, Wook Ryol Hwang, and Chongyoup Kim Copyright © 2012 Hyun Jun Jeong et al. All rights reserved. Wed, 31 Oct 2012 11:47:58 +0000 http://www.hindawi.com/journals/mse/2012/125405/ Computational fluid dynamics (CFD) analysis was performed in four different 90 degree elbows with air-water two-phase flows. The inside diameters of the elbows were 6.35 mm and 12.7 mm with radius to diameter ratios () of 1.5 to 3. The pressure drops at two different upstream and downstream locations were investigated using empirical, experimental, and computational methods. The combination of three different air velocities, ranging from 15.24 to 45.72 m/sec, and nine different water velocities, in the range of 0.1–10.0 m/s, was used in this study. CFD analysis was performed using the mixture model and a commercial code, FLUENT. The comparison of CFD predictions with experimental data and empirical model outputs showed good agreement. Quamrul H. Mazumder Copyright © 2012 Quamrul H. Mazumder. All rights reserved. Tue, 30 Oct 2012 13:48:36 +0000 http://www.hindawi.com/journals/mse/2012/501251/ This paper proposes a (computer aided design) CAD variational geometry approach for the high-order dimension synthesis of one-DoF mechanisms based on the given velocity/acceleration of a moving platform along a prescribed trajectory. The objective of this approach is to determine the reasonable dimensions of the mechanisms when given the velocity or/and the acceleration of the moving platform along a prescribed trajectory. First, some concepts and mathematical foundations are explained for constructing the velocity/acceleration simulation mechanism of a general mechanism. Second, the inverse velocity/acceleration simulation mechanisms of the planar/spatial four-bar mechanisms with one-DoF are constructed by the CAD variational geometry. Third, when given the position and the velocity/acceleration of the coupler along a prescribed trajectory, all the reasonable dimensions of the planar/spatial four-bar mechanisms are solved from their simulation mechanisms. Yi Lu, Yang Lu, Nijia Ye, and Lin Yuan Copyright © 2012 Yi Lu et al. All rights reserved. Wed, 24 Oct 2012 09:01:56 +0000 http://www.hindawi.com/journals/mse/2012/863235/ A glazing façade subjected to blast loads has a structural behaviour that strongly differs from the typical response of a glazing system subjected to ordinary loads. Consequently, sophisticated modelling techniques are required to identify correctly its criticalities. The paper investigates the behaviour of a cable-supported façade subjected to high-level blast loading. Nonlinear dynamic analyses are performed in ABAQUS/Explicit using a sophisticated FE-model (M01), calibrated to dynamic experimental and numerical results. The structural effects of the total design blast impulse, as well as only its positive phase, are analyzed. At the same time, the possible cracking of glass panels is taken into account, since this phenomenon could modify the response of the entire façade. Finally, deep investigations are dedicated to the bearing cables, since subjecting them to elevated axial forces and their collapse could compromise the integrity of the cladding wall. Based on results of previous studies, frictional devices differently applied at their ends are presented to improve the response of the façade under the impact of a high-level explosion. Structural effects of various solutions are highlighted through dynamic simulations. Single vertical devices, if appropriately calibrated, allow reducing significantly the axial forces in cables, and lightly the tensile stresses in glass panes. Claudio Amadio and Chiara Bedon Copyright © 2012 Claudio Amadio and Chiara Bedon. All rights reserved. Mon, 22 Oct 2012 11:26:52 +0000 http://www.hindawi.com/journals/mse/2012/912071/ In this work, a feedback control algorithm was developed based on geometric control theory. A nonisothermal seeded continuous crystallizer model was used to test the algorithm. The control objectives were the stabilization of the third moment of the crystal size distribution () and the crystallizer temperature (); the manipulated variables were the stirring rate and the coolant flow rate. The nonlinear control (NLC) was tested at operating conditions established within the metastable zone. Step changes of magnitudes ±0.0015 and ±0.5°C were introduced into the set point values of the third moment and crystallizer temperature, respectively. In addition, a step change of ±1°C was introduced as a disturbance in the feeding temperature. Closed-loop stability was analyzed by calculating the eigenvalues of the internal dynamics. The system presented a stable dynamic behavior when the operation conditions maintain the crystallizer concentration within the metastable zone. Closed-loop simulations with the NLC were compared with simulations that used a classic PID controller. The PID controllers were tuned by minimizing the integral of the absolute value of the error (IAE) criterion. The results showed that the NLC provided a suitable option for continuous crystallization control. For all analyzed cases, the IAEs obtained with NLC were smaller than those obtained with the PID controller. Pedro Alberto Quintana-Hernández, Raúl Ocampo-Pérez, Salvador Tututi-Avila, and Salvador Hernández-Castro Copyright © 2012 Pedro Alberto Quintana-Hernández et al. All rights reserved. Wed, 17 Oct 2012 16:15:33 +0000 http://www.hindawi.com/journals/mse/2012/264693/ The projective integration method based on the Galerkin-free framework with the assistance of proper orthogonal decomposition (POD) is presented in this paper. The present method is applied to simulate two-dimensional incompressible fluid flows past the NACA0012 airfoil problem. The approach consists of using high-accuracy direct numerical simulations over short time intervals, from which POD modes are extracted for approximating the dynamics of the primary variables. The solution is then projected with larger time steps using any standard time integrator, without the need to recompute it from the governing equations. This is called the online projective integration method. The results by the projective integration method are in good agreement with the full scale simulation with less computational needs. We also study the individual function of each POD mode used in the projective integration method. It is found that the first POD mode can capture basic flow behaviors but the overall dynamic is rather inaccurate. The second and the third POD modes assist the first mode by correcting magnitudes and phases of vorticity fields. However, adding the fifth POD mode in the model leads to some incorrect results in phase-shift forms for both drag and lift coefficients. This suggests the optimal number of POD modes to use in the projective integration method. Sirod Sirisup and Montri Maleewong Copyright © 2012 Sirod Sirisup and Montri Maleewong. All rights reserved.