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In this paper, the effects of cell geometry and relative density on the high-cycle fatigue behavior of Titanium scaffolds produced by selective laser melting and electron beam melting techniques were numerically investigated by finite element analysis. The regular titanium lattice samples with three different unit cell geometries, namely, diamond, rhombic dodecahedron and truncated cuboctahedron, and the relative density range of 0.1–0.3 were analyzed under uniaxial cyclic compressive loading. A failure event based algorithm was employed to simulate fatigue failure in the cellular material. Stress-life approach was used to model fatigue failure of both bulk (struts) and cellular material. The predicted fatigue life and the damage pattern of all three structures were found to be in good agreement with the experimental fatigue investigations published in the literature. The results also showed that the relationship between fatigue strength and cycles to failure obeyed the power law. The coefficient of power function was shown to depend on relative density, geometry and fatigue properties of the bulk material while the exponent was only dependent on the fatigue behavior of the bulk material. The results also indicated the failure surface at an angle of 45° to the loading direction. [ABSTRACT FROM AUTHOR]

Diesel–electric locomotives have significant fuel consumption. In this study, fuzzy look-ahead control is considered as an online approach for fuel consumption optimization. A fuzzy controller will modify the desired speed profile by accounting for the gradient and speed limits of the path ahead. Journey time increment is used as an optimization constraint. The existing models for train motion simulation are calculating the fuel consumption by an indirect index. A new model for train-movement simulation is proposed to calculate fuel consumption more accurately. This model considers the locomotive subsystems and satisfies the experimental fuel consumption data specified in the locomotive's catalog. Simulation of a train with a GM Sd40-2 on three local tracks showed considerable reduction in fuel consumption along with an acceptable journey time increment. Simulation results also showed that fuzzy look-ahead controller has very faster calculations in comparison with the controller based on the dynamic programming method. [ABSTRACT FROM AUTHOR]

In this paper a package for designing, modelling and simulation of three hybrid powertrains are presented. These powertrains are Electric hybrid, Hydraulic hybrid and Flywheel hybrid. The differences among the proposed hybrid powertrains include the energy storage system components, the secondary power converter and also the powertrain configuration. The O457 city bus is considered as the benchmark vehicle. At first, the design process for each hybrid powertrain which is based on the power requirements of the bus in any driving condition is presented. Then, the powertrains modelling using MATLAB/Simulink as a powerful simulating tool is presented. The models are feed-forward and resemble the real world driving conditions. Each model has the blocks for the main components of the corresponding propulsion system. The most important stage in the modeling process is implementing of the components efficiency in each powertrain. Moreover, there is a block in each hybrid powertrain model for the energy management. Finally, the simulation results for comparing the usefulness of the hybrid powertrains are presented. The results indicate that the electric hybrid powertrain has the most effect on reducing the bus fuel consumption. But regarding the fabrication expenses and manufacturing complexity, the hydraulic hybrid powertrain is recommended. [ABSTRACT FROM AUTHOR]

A compressive-sensing approach called Sparse Representation Classifier (SRC) is applied to the classification of bottlenose dolphin whistles by type. The SRC algorithm constructs a dictionary of whistles from the collection of training whistles. In the classification phase, an unknown whistle is represented sparsely by a linear combination of the training whistles and then the call class can be determined with an l1-norm optimization procedure. Experimental studies conducted in this research reveal the advantages and limitations of the proposed method against some existing techniques such as K-Nearest Neighbors and Support Vector Machines in distinguishing different vocalizations. [ABSTRACT FROM AUTHOR]

An image processing technique called Local Binary Patterns (LBP) has been explored for its ability to generate feature vectors for dolphin vocalization classification. The LBP operator eliminates the need for contour tracing, denoising, and other prior processing. In an experimental study of classifying dolphin whistle types, the performance of the LBP operation was compared with that of the popular contour-based Time-Frequency Parameters (TFP) approach. The preliminary experimental results illustrate that the LBP method produces more consistent classifier accuracy of dolphin whistle calls even when the contour shapes are complex and populated with impulsive clicks and anthropogenic harmonics. [ABSTRACT FROM AUTHOR]

Abstract: Due to increasing use of clay/epoxy nanocomposites in industry, investigation of mechanical properties of clay nanocomposites has become of great interest. While the stiffening mechanism of clay nanocomposites is well documented, there is still not a clear understanding about how addition of clays affect the fracture behavior of clay/epoxy nanocomposites. The main aim of this paper is to measure and explain the effect of clays on ductility reduction of these nanocomposites. First, epoxy and clay/epoxy nanocomposites with different clay weight ratio were built. Then, the damage parameters of epoxy and clay/epoxy nanocomposites were measured by variation of the elasticity modulus. Based on loading–unloading experiments, the Lemaitre damage parameters for epoxy and clay/epoxy nanocomposites were extracted. Crack initiation and propagation in dog-bone sample were simulated for epoxy and clay/epoxy nanocomposites using the eXtended Finite Element Method (XFEM). The comparison between experimental and numerical results shows that the proposed method can predict the crack initiation location and propagation path in clay/epoxy nanocomposites. [Copyright &y& Elsevier]

Kinetics for bioethanol production from glucose using Saccharomyces cerevisiae (PTCC 24860) was experimentally studied in a batch membrane bioreactor and a conventional bioreactor using a pervaporation process. For pervaporation, a dense hydrophobic polydimethylsiloxane membrane was used. The batch membrane bioreactor resulted in increase of cell density, improved productivity and yield. A generic model was developed which can give a unique description for production of bioethanol within both batch membrane bioreactor and conventional bioreactor. Coupled describing equations of the model were solved by means of genetic algorithm approach. The logistic model considered for expression of growth kinetics and kinetic parameters calculated through the genetic algorithm. The results demonstrated that this generic model is capable to describe reasonably the behavior of both the conventional bioreactor and the batch membrane bioreactor with the highest correlation coefficient (0.979 and 0.987, respectively). [ABSTRACT FROM AUTHOR]

Hydraulic engine mounts are generally applied to the aerospace and automotive applications for the purpose of cabin noise and vibration reduction. By careful selection of mount design parameters, at a certain frequency called the notch frequency, the dynamic stiffness will be smaller than the static stiffness. Following the notch frequency there will be a frequency, called the peak frequency, where the dynamic stiffness is much higher than the static stiffness. Increase in the dynamic stiffness above the static stiffness is not desirable because of the increase in transmitted force to the airframe or the chassis. Here in this paper, a new hydraulic engine mount design is proposed that uses two working fluids. This new design has two notch frequencies and two peak frequencies. Under special conditions, the peak frequency can be eliminated. As a result, one can obtain a hydraulic engine mount design with only one notch frequency but no peak frequency, by using a controllable fluid or a high viscosity fluid as one of the working fluids. The new hydraulic engine mount design, its mathematical model, and some discussions on the simulation results are presented. [ABSTRACT FROM PUBLISHER]