bluuebunny/crossref_metadata_2025 huggingface dataset:
Na+/Ca2+ exchange and Na+/K+‐ATPase in the heart
Authors: Shattock Michael J. , Ottolia Michela , Bers Donald M. , Blaustein Mordecai P. , Boguslavskyi Andrii , Bossuyt Julie , Bridge John H. B. , Chen‐Izu Ye , Clancy Colleen E. , Edwards Andrew , Goldhaber Joshua , Kaplan Jack , Lingrel Jerry B. , Pavlovic Davor , Philipson Kenneth , Sipido Karin R. , Xie Zi‐Jian
Published: March 2015

This paper is the third in a series of reviews published in this issue resulting from the University of California Davis Cardiovascular Symposium 2014: Systems approach to understanding cardiac excitation–contraction coupling and arrhythmias: Na+ channel and Na+ transport. The goal of the symposium was to bring together experts in the field to discuss points of consensus and controversy on the topic of sodium in the heart. The present review focuses on cardiac Na+/Ca2+ exchange (NCX) and Na+/K+‐ATPase (NKA). While the relevance of Ca2+ homeostasis in cardiac function has been extensively investigated, the role of Na+ regulation in shaping heart function is often overlooked. Small changes in the cytoplasmic Na+ content have multiple effects on the heart by influencing intracellular Ca2+ and pH levels thereby modulating heart contractility. Therefore it is essential for heart cells to maintain Na+ homeostasis. Among the proteins that accomplish this task are the Na+/Ca2+ exchanger (NCX) and the Na+/K+ pump (NKA). By transporting three Na+ ions into the cytoplasm in exchange for one Ca2+ moved out, NCX is one of the main Na+ influx mechanisms in cardiomyocytes. Acting in the opposite direction, NKA moves Na+ ions from the cytoplasm to the extracellular space against their gradient by utilizing the energy released from ATP hydrolysis. A fine balance between these two processes controls the net amount of intracellular Na+ and aberrations in either of these two systems can have a large impact on cardiac contractility. Due to the relevant role of these two proteins in Na+ homeostasis, the emphasis of this review is on recent developments regarding the cardiac Na+/Ca2+ exchanger (NCX1) and Na+/K+ pump and the controversies that still persist in the field.
Fatigue Life Prediction of Drill-String Subjected to Random Loadings
Authors: Zheng Jiahao , Qiu Hongyuan , Yang Jianming , Butt Stephen
Published: March 2015

Based on linear damage accumulation law, this paper investigates the fatigue problem of drill-strings in time domain. Rainflow algorithms are developed to count the stress cycles. The stress within the drill-string is calculated with finite element models which is developed using Euler-Bernoulli beam theory. Both deterministic and random excitations to the drill-string system are taken into account. With this model, the stress time history in random nature at any location of the drill-string can be obtained by solving the random dynamic model of the drill-string. Then the random time history is analyzed using rainflow counting method. The fatigue life of the drill-string under both deterministic and random excitations can therefore be predicted.
Performance and Vibration of a Double Volute Centrifugal Pump: Effect of Impeller Trimming
Authors: Khalifa Atia E.
Published: March 2015

The fluid-structure interaction phenomenon, as manifested by the pressure pulsation excited by rotor-stator interaction, is the main cause of flow-induced vibrations at the blade passing frequency in large and high pressure centrifugal pumps. This phenomenon is strongly influenced by the clearance gap between impeller and volute diffusers/tongues and the geometry of impeller blade at exit. One way to reduce the effects of this interaction is to increase the effective gap by trimming the impeller. However, trimming the impeller will affect the pump performance and the flow pattern inside the pump volute. In the present work, experiments are carried out using a single stage, double-volute centrifugal model pump to investigate the effect of increasing the clearance gap by trimming the impeller on pump performance and vibration. Pressure fluctuations around the impeller inside pump volute are monitored and recorded. The clearance gap was increased three times by trimming the impeller radius by 1 mm, 2 mm, and 3 mm; respectively. Results showed that trimming the impeller reduces the pump vibration at the expense of the developed pump head. The minimum vibration was measured at the best efficiency point of the pump and the vibration amplitude increases when the pump operates at off-design conditions. Impeller trimming is more effective at flow rates equal to and higher that the design flow rate.
Drug Accumulation Into Single Drug-Sensitive and Drug-Resistant Prostate Cancer Cells Conducted on the Single Cell Bioanalyzer
Authors: Khamenehfar Avid , Liu Ji , Cai Jia , Wong Michael , Li Paul C. H. , Ling Patrick , Russell Pamela
Published: March 2015

Multidrug resistance (MDR) occurs in prostate cancer, and this happens when the cancer cells resist chemotherapeutic drugs by pumping them out of the cells. MDR inhibitors such as cyclosporin A (CsA) can stop the pumping and enhance the drugs accumulated in the cells. The cellular drug accumulation is monitored using a microfluidic chip mounted on a single cell bioanalyzer. This equipment has been developed to measure accumulation of drugs such as doxorubicin (DOX) and fluorescently labeled paclitaxel (PTX) in single prostate cancer cells. The inhibition of drug efflux on the same prostate cell was examined in drug-sensitive and drug-resistant cells. Accumulation of these drug molecules was not found in the MDR cells, PC-3 RX-DT2R cells. Enhanced drug accumulation was observed only after treating the MDR cell in the presence of 5 μM of CsA as the MDR inhibitor. We envision this monitoring of the accumulation of fluorescent molecules (drug or fluorescent molecules), if conducted on single patient cancer cells, can provide information for clinical monitoring of patients undergoing chemotherapy in the future.
A Numerical Investigation on the Performance of Novel Sister Shaped Single-Hole Configurations for Film Cooling Flow
Authors: Khajehhasani Siavash , Jubran Bassam A.
Published: March 2015

The film cooling performance using novel sister shaped single-hole (SSSH) schemes are numerically investigated in the present study. The downstream, upstream and up/downstream SSSH configurations are formed by merging the discrete sister holes to the primary injection hole through a series of specific orientations. The obtained results are compared with a conventional cylindrical hole and a forward diffused shaped hole. The RANS simulations are performed using the realizable k-ε model with the standard wall function. Results are presented for low and high blowing ratios of 0.25 and 1.5, respectively. The film cooling effectiveness is notably increased for the novel shaped holes, particularly at the high blowing ratio of 1.5. Furthermore, a considerable decrease in the jet lift-off has been achieved for the proposed film hole geometries, wherein fully attached flow to the wall surface is observed for the upstream and up/downstream SSSH schemes.
Monte Carlo Simulation of Backscatter Signals Through Thin Scattering Layers for Biomedical Applications
Authors: Eze R. , Hassebo Y.
Published: March 2015

Monte Carlo simulation of photon transport is formulated to solve transient radiative transfer equation through thin multilayered scattering-absorbing media with inhomogeneous properties. Though thin layers might seem to be geometrically insignificant, contribution of their radiative properties is relevant in predicting the behavior of most bioengineering, biomedical and space applications. Most traditional Monte Carlo models often fail to capture the presence of thin layers and account for its radiative properties. If the Monte Carlo model is implemented without unique features then the results of the simulation would show incorrect effect of thin layers since the path length of most photons would be significantly larger than the layer thickness and the evaluated photon travel path length would simply not feel the existence of the layer. Numerical and algorithmic features for computation of radiation transport through thin scattering and absorbing layers using the traditional Monte Carlo and an enhanced Monte Carlo model with features specifically developed for thin layers is presented and implemented for the analysis of backscattered radiation. It is observed that while Monte Carlo without special features defines the radiative effect of the layers, the refined technique indicates that layers have a great impact on the backscattered light, especially if the layer properties are distinctly different from those of the contiguous layers. The results have significant implications in the study of diagnostic applications of laser in biomedical applications since backscattered light is one of the non-invasive techniques available for detection of diseases and complements other known methods. Analyses of backscattered signals have also found use in the noninvasive methods of medical use especially in skin diagnostics.
Inflow Conditions and the Wall Shear Stress Characteristics of a Biofluid in Separated and Reattached Flow Regions
Authors: Hammad Khaled J.
Published: March 2015

The influence of inflow conditions and human blood rheology on the wall shear stress distribution in a confined separated and reattached flow region is investigated. The governing mass and momentum conservation equations along with the Herschel-Bulkley rheological model are solved numerically using a finite-difference scheme. A parametric study is performed to reveal the influence of uniform and fully-developed inflow velocity profiles on the wall shear stress (WSS) characteristics using hemorheological models that account for the yield stress and shear-thinning non-Newtonian characteristics of human blood. The highest WSS or WSSmax, is always observed inside the flow separation region at a location corresponding to that of the corner vortex center. Uniform inflow results in higher WSSmax values in comparison with fully-developed inflow for moderate upstream flow restrictions. The opposite trend is observed for severe flow restrictions. Uniform inflow always results in smaller flow separation regions and WSSmax values at locations closer to the flow restriction plane. The yield shear-thinning hemorheological model always results in the highest observed peak WSS. The yield stress impact on WSS distribution is most pronounced in the case of severe restrictions to the flow.
Applying Kane’s Method to Model the Response of the Human Body to Whole-Body Vibration
Authors: Gantzer Emma , Duan Shanzhong (Shawn) , Binkley Teresa
Published: March 2015

Low magnitude, high frequency whole-body vibration (WBV) has been found to increase bone mineral density in both animal and clinical studies [1,2,3]. The mechanism behind this phenomenon is unknown and a model would be beneficial to assist in analyzing the effects of WBV on the human skeleton. In this paper, Kane’s method is used to find the equations of motion for a multi-body model of the human body standing on a vibration platform [4]. The model consists of nine rigid bodies connected by ideal joints that simulate the skeletal structure of the human body. Spring and damper elements represent the ligaments and tendons connecting the rigid bodies; a sinusoidal force function denotes the vibration input of the platform. This model is lumped, assuming no relative motion between the feet and the vibration platform. The equations of motion generated by Kane’s method are solved in MATLAB using fourth-order Runge-Kutta. The results from the simulation were compared to experimental data in order to validate the model.
A Finite Element Solution for Fully Intrinsic Plate Theory
Authors: Sotoudeh Zahra
Published: March 2015

The fully intrinsic equations for plates (and analogous ones for shells), although equally as elegant as the corresponding beam equations, have neither been used for general-purpose finite element nor multi-flexible-body analysis. The fully intrinsic equations for plates have the same advantages of fully intrinsic equations for beams. These equations are geometrically exact, the highest order of nonlinearities is only of second order, and they do not include rotation parameters. We present a finite element formulation for these equations, and then investigate different possible boundary conditions and loading situations on simplified linear version.
Validation of a Conventional Finite Element Model for Simulation of a Micropunching Process
Authors: Sagar Amrit , Nehme Christopher R. , Saigal Anil , James Thomas P.
Published: March 2015

Finite element analysis (FEA) of metal microforming processes may require Crystal Plasticity Finite Element (CPFE) formulations to incorporate material inhomogeneity as feature size approaches grain size. Presently, it is unknown if the micropunching process, where holes are formed by shearing thin metal foils with a thickness on the same scale as grain size, can be accurately simulated by using the material’s bulk material properties or if CPFE is required. In the current research, validity of conventional FEA in simulating micropunching is investigated as CPFE formulations have yet to be integrated with most commercially available programs. Using DEFORM finite element software, strain hardening and strain rate hardening material models were employed to approximate flow stress when punching 200 μm diameter holes in 25 μm thick annealed copper foil. For validation of peak punching force, micro holes were fabricated with a nominal diameter of 200 μm for die clearances ranging from 7.6% to 48% of material thickness. The average grain size of the foil was determined to be approximately 47 μm. Therefore, micropunching was predominantly through a single grain across foil thickness and less than a grain in the direction of radial die clearance. Results indicate that the homogeneous material model in DEFORM is capable of predicting the maximum punching forces with reasonable accuracy, concluding that a CPFE model is not necessary for this category of micropunching. Regardless of die clearance, the maximum punching force was approximately 3 N.
Spherical Indentation Testing on Ballistic Gelatin and Perma-Gel
Authors: Caron-Laramée Amélie , Brouillette Martin
Published: March 2015

This paper reports on a series of indentation tests performed on ballistic gelatin (10%) and Perma-Gel. In these experiments, both gels were submitted to strain rates varying from 0.1 and 2.7 s−1 in quasi-static indentation. Two methods were used to evaluate the Young’s modulus from quasi-static indentation test: the Hertz theory and the Oliver-Pharr model. The dependence of strain rate was also analyzed. Finally, dynamic indentation tests were performed on both gels at frequencies of 0.1 and 1.0 Hz to evaluate the gel’s viscoelastic properties characterized by the storage modulus, the loss modulus and the phase angle.
An Evaluation of the Moving Horizon Estimation Algorithm for Online Estimation of Battery State of Charge and State of Health
Authors: Pattel Bibin , Borhan Hoseinali , Anwar Sohel
Published: March 2015

Moving Horizon Estimation (MHE) has emerged as a powerful technique for tackling the estimation problems of the state of dynamic systems in the presence of constraints, nonlinearities and disturbances. In this paper, the Moving Horizon Estimation approach is applied in estimating the State of Charge (SoC) and State of Health (SoH) of a battery and the results are compared against those for the traditional estimation method of Extended Kalman Filter (EKF). The comparison of the results show that MHE provides improvement in performance over EKF in terms of different state initial conditions, convergence time, and process and sensor noise variations.
Simulation of Multi-Closed Loop Control With Feed Forward Control of Micro-Vibration Isolation Platform
Authors: Wu Qianqian , Yue Honghao , Liu Rongqiang , Ding Liang , Deng Zongquan
Published: March 2015

Micro vibration in the ideal-zero gravity environments has complicated science experiment results. A magnetic levitation vibration isolation platform is needed to isolate the vibration source to provide acceptable acceleration level in low frequency range. The configuration of the Lorentz actuators is discussed in the paper. And the modeling of the transformation matrix from the force to the current is deduced. In order to generate desired force, the current is needed to predict precisely. To study the characteristics of the system, the single degree of freedom system is analyzed. A multi-closed loop control scheme is put forward to achieve vibration isolation control. To evaluate the effect of each control parameter, frequency domain analysis of the transfer function is simulated. In order to further increase the control effectiveness, a feed forward compensation control algorithm is added to control the vibration of cables that connect the upper platform and the base. By regulating these control parameters, bode curves can be obtained. Comparing the two methods, it can be concluded that the control method with feed forward compensation is better than the one without that.
Anti-Sloshing Effects of Longitudinal Partial Baffles in a Partly-Filled Container Under Lateral Excitation
Authors: Kolaei Amir , Rakheja Subhash , Richard Marc J.
Published: March 2015

This study is aimed at analysis of transient lateral slosh in a partially-filled cylindrical tank with different designs of longitudinal partial baffles using a coupled multimodal and boundary-element method. A boundary element method is initially formulated to solve the eigenvalue problem of free liquid slosh, assuming inviscid, incompressible and irrotational flows. Significant improvement in computational time is achieved by reducing the generalized eigenvalue problem to a standard one involving only the velocity potentials on the half free-surface length using the zoning method. The generalized coordinates of the free-surface oscillations under a lateral excitation are then obtained from superposition of the natural slosh modes. The lateral slosh force is also formulated in terms of the generalized coordinates and hydrodynamic coefficients. The validity of the model is illustrated through comparisons with available analytical solutions. Two different designs of longitudinal baffles are considered: bottom- and top-mounted baffles. The effect of different baffle designs on the normalized slosh frequencies, modes and lateral force are investigated. It is shown that the multimodal method yields computationally efficient solutions of liquid slosh within moving baffled containers. The results suggest that the effectiveness of baffles in suppressing the liquid oscillations is strongly affected by the baffle length relative to the free-surface height. The top-mounted baffle yields the greatest effectiveness, when it pierces the free-surface. The bottom-mounted baffle, however, may not be considered as an efficient mean for controlling the liquid slosh in tank vehicles where the liquid fill height is above 50%.
Wavelet-Based Filtered-X LMS Algorithm for the Control of Permanent Magnet Synchronous Motors
Authors: Tong Xiaomeng , Suh C. Steve
Published: March 2015

Permanent Magnet Synchronous Motor (PMSM) can behave chaotically for a certain range of its parameters. To improve its dynamical behavior and enable a robust control of the rotor angular speed, a novel method combining the wavelet transform with the filtered-x LMS algorithm is presented in this paper. Without linearizing the model so as to not advertently misinterpret the underlying dynamics, the method can identify the nonlinear PMSM model with adaptive filters in real-time and guarantee a comprehensive control in both the time and frequency domains. Firstly, the physical PMSM model is analyzed and its chaotic behavior without control is investigated. The wavelet-based filtered-x LMS is then applied to the nonlinear PMSM system subject to desired angular speeds that are constant and varying harmonically in time. Numerical studies show that chaotic behaviors are effectively mitigated and the system output matches the desired angular speed after the initial transient period, thus demonstrating the feasibility of the method for the control of PMSMs.
Numerical Analysis of Flexible Rotor With Nonlinear Bearings and Squeeze Film Dampers
Authors: Cao Jianming , Dimond Timothy , Allaire Paul
Published: March 2015

This paper presents dynamic behaviors of a flexible rotor supported on nonlinear bearings and nonlinear squeeze film dampers. The nonlinear bearing and damper forces, which depend on instantaneous nodal displacements and velocities, are calculated at each time step through closed form solutions of Reynolds equation. Such combinations of fluid film bearings and squeeze film dampers are often used in industrial machines such as compressors and steam turbines to increase system damping. No previous works have studied the nonlinear time transient analysis of a fluid film bearing and damper combination. To describe the coupled motion of shaft, bearing and squeeze film damper, a method of assembling both the linear rotor and the nonlinear components is developed. The numerical transient analyses are applied to a 3-disk rotor supported with nonlinear short plain journal bearings and nonlinear short squeeze film dampers. Squeeze film dampers, introduced to the system, increase dynamic stability of the system under a wide range of system rotational speeds, and decrease the bearing forces under severe unbalance forces. Different nonlinear rotor dynamic behavior, such as sub-harmonic, super-harmonic and torus orbits are shown in transient analyses. This type of analysis can be employed to study whether a centering spring is required in the damper or not.
Modelling of Orthogonal Cutting of Idealized FRP Composites
Authors: Agarwal Harshit , Gururaja Suhasini
Published: March 2015

Finite Element modelling (FEM) of orthogonal cutting of Idealized carbon fiber reinforced plastics (I-CFRP) specimens has been presented in this work. I-CFRP specimens were prepared by embedding carbon fibre tows in an epoxy matrix at 5 mm center to center spacing. Force signals and full-field strains were measured during orthogonal cutting. 3D-FE modelling of the process has been done in ABAQUS/Explicit. Failure mechanisms during orthogonal cutting have been incorporated in the FE model through a cohesive zone model of the fibre-matrix interface, and a ductile damage criteria with damage evolution has been employed for the epoxy matrix. The model shows that matrix damage is significant with marginal fibre matrix debonding. Strains in the model have been compared with results from DIC and show a close match.
Super Imposed Length Oscillations (SILO) and Their Effect on Asthmatic Models (Acute and Chronic) During an Asthmatic Attack
Authors: Jo-Avila Miguel , Roos Kevin , Al-Jumaily Ahmed , Lu Jun
Published: March 2015

The main driving mechanism during an asthmatic attack is the hyperconstriction of airway smooth muscle (ASM), which reduces the airway lumen and makes normal breathing difficult. The contraction can be relieved using bronchodilator drugs such as Isoproterenol, which induce temporary relaxation of the constricted airways. Pharmacological treatments are widely used in asthma, but their effectiveness varies from one subject to another, as do their side effects. Studies have shown that mechanical oscillations equivalent to physiological patterns such as breathing and deep inspiration in healthy airways can induce airway relaxation, but this type of response is not observed in asthmatics. Length oscillations seem to be a non-medicinal approach to treat ASM hyperconstriction present in many respiratory diseases such as asthma. Currently little is known about the effect of other oscillations’ patterns and their combination with breathing and deep inspiration on healthy and asthmatic airways during an asthmatic attack. Preliminary results obtained from in vitro and in vivo experiments in our laboratory indicate that the use of super imposed length oscillations (SILO) over normal breathing patterns can induce relaxation during an induced asthmatic attack on healthy and asthmatic subjects. These tests have been carried out using animal models which have been prepared under an acute protocol for the disease (new asthmatics), but these oscillations still remain to be tested in chronic asthmatic models (chronic asthmatics).
A General Method for Kinematic Retargeting: Adapting Poses Between Humans and Robots
Authors: Tosun Tarik , Mead Ross , Stengel Robert
Published: March 2015

This paper presents a method for kinematic retargeting that is general to a broad class of kinematic chains. Kinematic retargeting is the adaptation of a pose or motion from one kinematic embodiment to another. Our method distinguishes itself in its ability to adapt poses to new robots with very little configuration by the user. We accomplish this by defining two general metrics for retargeting and minimizing a cost function which is the weighted sum of these two metrics. This allows the method to automatically adapt poses between source and target chains that have different link lengths and degrees of freedom.

These capabilities address a specific problem in Human-Robot Interaction (HRI), where behaviors are often defined in a robot-specific manner. The ability to automatically adapt behaviors from humans to new robots, and from one robot to another, will facilitate experimental repeatability. Through simulation and experiments, we demonstrate that our method is effective in adapting poses across chains with different numbers of joints, and in adapting socially expressive gestures from a human to two very different robots.
The Generalized State Dependent Riccati Equation Control of Continuous Time Nonlinear Systems
Authors: Wang Xin , Long James , Sun Wangping , Lian Wen
Published: March 2015

This paper presents a novel Generalized State Dependent Riccati Equation control approach with the purpose of providing a more effective control design framework for continuous time nonlinear systems to achieve a mixed Nonlinear Quadratic Regulator and H∞ control performance criteria. By solving the Generalized State Dependent Riccati Equation, the optimal control solution is found to achieve mixed performance objectives guaranteeing nonlinear quadratic optimality with inherent stability property in combination with H∞ type of disturbance reduction. An efficient computational algorithm is given to find the solution to the Generalized State Dependent Riccati Equation. The efficacy of the proposed technique is used to design the control system for inverted pendulum, an under-actuated nonlinear mechanical system.
A Kalman Filter Framework for High-Dimensional Sensor Fusion Using Stochastic Non-Linear Networks
Authors: Lloyd George M.
Published: March 2015

The textbook Kalman Filter (LKF) seeks to estimate the state of a linear system based on having two things in hand: a.) a reasonable state-space model of the underlying process and its noise components; b.) imperfect (noisy) measurements obtained from the process via one or more sensors. The LKF approach results in a predictor-corrector algorithm which can be applied recursively to correct predictions from the state model so as to yield posterior estimates of the current process state, as new sensor data are made available. The LKF can be shown to be optimal in a Gaussian setting and is eminently useful in practical settings when the models and measurements are stochastic and non-stationary. Numerous extensions of the KF filter have been proposed for the non-linear problem, such as extended Kalman Filters (EKF) and ‘ensemble’ filters (EnKF). Proofs of optimality are difficult to obtain but for many problems where the ‘physics’ is of modest complexity EKF’s yield algorithms which function well in a practical sense; the EnKF also shows promise but is limited by the requirement for sampling the random processes. In multi-physics systems, for example, several complications arise, even beyond non-Gaussianity. On the one hand, multi-physics effects may include multi-scale responses and path dependency, which may be poorly sampled by a sensor suite (tending to favor low gains). One the other hand, as more multi-physics effects are incorporated into a model, the model itself becomes a less and less perfect model of reality (tending to favor high gains). For reasons such as these suitable estimates of the joint system response are difficult to obtain, as are corresponding joint estimates of the sensor ensemble. This paper will address these issues in a two-fold way — first by a generalized process model representation based on regularized stochastic non-linear networks (Snn), and second by transformation of the process itself by an adaptive low-dimensional subspace in which the update step on the residual can be performed in a space commensurate with the available information content of the process and measured response.
Active Vibration Control of a Hanged Rectangular Plate Partially Submerged Into Fluid by Using Piezoelectric Sensors and Actuators
Authors: Kwak Moon K. , Yang Dong-Ho
Published: March 2015

This paper is concerned with the active vibration control of a hanged rectangular plate partially submerged into a fluid by using piezoelectric sensors and actuators bonded to the plate. A dynamic model for the plate is derived by using the Rayleigh-Ritz method and the fluid effect is modeled by the virtual mass increase that is obtained by solving the Laplace equation. The natural vibration characteristics of the plate in air obtained theoretically are in good agreement with the experimental results. The changes in natural frequencies due to the presence of fluid were measured and compared to the theoretical predictions. Experimental results show that the theoretical predictions are in good agreement with the experimental results. The natural vibration characteristics of the plate both in air and in water are used for the active vibration control design. In this study, the multi-input and multi-output positive position feedback controller was designed based on the natural vibration characteristics and implemented by using a digital controller. Experimental results show that the vibration of the hanged rectangular plate both in air and partially submerged into a fluid can be successfully suppressed by using piezoelectric sensors and actuators.
On the Dynamics of Pressure Relief Valves With External Pilot for ICE Lubrication
Authors: Rundo Massimo
Published: March 2015

The paper analyzes the influence on the stability of the remote pilot in pressure relief valves used for engine lubrication. Such valves are mainly used to discharge the excess flow generated by a fixed displacement pump, moreover they can also be used as pilot stage to control the displacement in the new generation of vane pumps. In the paper the transfer function that relates the pressure in the main gallery with the valve spool position is determined. It was found that, when the valve is provided with an external pilot, the interaction between the hydraulic inductance of the pilot pipe and the spool decreases by many times the mechanical frequency of the valve, leading to a reduction of the stability. The experimental procedure used to measure the frequency response of the valve is also described. The test rig was provided with a servovalve used to generate a sinusoidal excitation pressure with variable frequency. The valve frequency response was evaluated by means of two pressure transducers at the two ends of the pilot channel. Finally the influence on the stability of some geometric parameters is analyzed by means of a simulation model in the AMESim environment.
Nonlinear Vibration of Nanobeam With Quadratic Rational Bezier Arc Curvature
Authors: Askari Hassan , Saadatnia Zia , Esmailzadeh Ebrahim
Published: March 2015

Nonlinear vibration of nanobeam with the quadratic rational Bezier arc curvature is investigated. The governing equation of motion of the nanobeam based on the Euler-Bernoulli beam theory is developed. Accordingly, the non-uniform rational B-spline (NURBS) is implemented in order to write the implicit form of the governing equation of the structure. The simply-supported boundary conditions are assumed and the Galerkin procedure is utilized to find the nonlinear ordinary differential equation of the system. The nonlinear natural frequency of the system is found and the effects of different parameters, namely, the waviness amplitude, oscillation amplitude, aspect ratio, curvature shape and the Pasternak foundation coefficient are fully investigated. The hardening and softening responses of the natural frequency of structure are detected for variations of the shape and amplitude of the curvature waviness. It is revealed that the ratio of nonlinear to linear frequency increases with an increase in the oscillation amplitudes. It is found that by increasing the Pasternak foundation coefficient, the ratio of nonlinear to linear frequency decreases.
Using Simple Structural Beam Model to Optimize for Bending Stiffness and Vibration in Automotive Structures
Authors: Wood Ian , Barari Ahmad , Esmailzadeh Ebrahim
Published: March 2015

Prior research has shown that the design of a vehicle’s structure has a substantial impact on its overall performance under static loading [1], since the structure affects other components of the vehicle aside from the body. In addition to the past research, dynamic loading is added in this paper as a parameter for design. Bending stiffness and weight are still important factors to consider, since a stiffer structure (higher stiffness) means longer life and stability. A lighter vehicle translates to better fuel economy, lower cost and higher performance. Simple Structural Beams are used to model the structure, where several beam elements are used in the setup. The cross-section properties are analyzed to determine the structure’s weight, bending stiffness, natural frequency and amplitude of vibration. In order to find an acceptable solution, the design must avoid the possibility of resonance. Vibration has a large impact on a structure’s performance, the larger the amplitude, the more uncomfortable the ride is. The goal of this research is to obtain a design that will optimize for vibration and for bending stiffness and weight. The purpose of the optimized design is to provide the best performance and most comfortable ride to the driver. The optimization process is automated iteratively and solves for the beam dimensions that correspond to the optimized parameters.
Concurrent Estimation of a Vehicle’s Mass and Auxiliary Power
Authors: Fard Soheil Mohagehghi , Khajepour Amir
Published: March 2015

The goal of this paper is to estimate the mass and auxiliary power of a vehicle simultaneously. Auxiliary power is the portion of the load power that is consumed by any auxiliary devices such as A/C compressor which is connected to the engine directly. This estimation has many potential applications especially in power management control systems of hybrid and plug-in-hybrid vehicles to improve their efficiency.

The parameter estimation algorithm is based on power balance of the vehicle. That is, total generated power by the engine should be equal to the power required for moving the vehicle plus the power consumed by the auxiliary devices. After developing the system model, Kalman filter is applied for the estimation of the auxiliary power and vehicle mass.

The proposed estimation algorithm uses the signals available through the vehicle control area network (CAN), and no extra sensor is required. It is assumed that the road grade is provided by a Global Positioning System (GPS) installed in the car. Simulations are presented to show the performance of the estimation algorithm in both city and highway driving cycles. The estimated and actual results are in very good agreement.
Controlling Bifurcation and Dynamic Behavior in Vibro-Impact System
Authors: Kuo Chi-Wei , Suh C. Steve
Published: March 2015

Impact oscillators are found in many applications. Some of the applications inadvertently experience the undesirable effect of vibro-impact called grazing bifurcation. For example, fitting joints are commonly considered in mechanical design. However, the grazing behavior of a loose fitting joint in response to the thermal variation of the working environment may cause unpredictable damage. In this paper, the Newtonian model of a vibro-impact system is investigated. The model system exhibits complex grazing dynamics that is highly nonlinear. The generation of grazing phenomena along with the corresponding periodic solution of the particular type of bifurcation is elaborated. The system is characterized using phase portraits. Since grazing and route-to-chaos are difficult to control, a novel concept capable of simultaneous control of vibration amplitude in the time-domain and spectral response in the frequency-domain is applied to develop a viable control scheme. The concept has been demonstrated working well for the control of dynamic instability including bifurcation and chaos in many engineering systems. The developed controller explores wavelet adaptive filters and filtered-x least mean square algorithm to the successful mitigation of the various states of dynamic instability of the vibro-impact system including grazing bifurcation and chaotic response. In addition, detail description is also given as to the setting of the control parameters such as control time step, sampling rate, wavelet filter vector, and desired targets.
Effect of Toe-Joint and Heel Height on Balancing of a Standing Biped
Authors: Kouchaki Ehsan , Sadigh Mohammad Jafar
Published: March 2015

Postural control of a standing bipedal model with toe-joints is studied. The model contains an inverted pendulum as the upper body and a foot, which consists of a heel-link and a toe-link. Taking advantage of ankle strategy, the biped is actuated by two torques at ankle-joint and toe-joint to regulate the upper body in upright position. To assess the stability of the system the Lyapunov exponents phenomena are used and the stability regions are calculated in the phase plane. To investigate the effect of toe-joint on control performance and the stability, the results are compared with those of a flat foot model without toe-joint. The relationship between heel’s height and balancing stability is investigated as well. The results show that toe-joint enhances stability of the system and reduces the actuator demand. This effect is more important especially in the case with high heel foot.
CFD-Based Aerodynamic Analysis of Damaged Delta Wings
Authors: Bou-Mosleh Charbel , Patel Samir
Published: March 2015

This paper addresses the aerodynamic response of damaged delta wings using steady-state Computational Fluid Dynamics simulations. Two types of delta wings are investigated: a High Speed Civil Transport (HSCT) wing and a F16 Block 40 Wing. These types of analyses are required to help predict wings’ remaining flight capability, after damage is inflicted (during battle). The damage is represented by a hole in the CFD model of both wings. Variations in the shape, size, location and orientation of holes are investigated. The lift and drag (at relatively low angles of attack) of the undamaged and damaged wings are predicted and compared. The obtained numerical results indicate that the location of the hole has a significant effect on the performance of the wing. Furthermore, straight-edged holes seem to have a larger impact on the wing’s aerodynamics as opposed to cylindrical-shaped holes. To make the shape of the hole as realistic as possible, petals emerging above the surface of the wing are introduced and their effect is also investigated. Results show a greater increase in drag compared to smooth cylindrical holes. Finally, and to better simulate the jet in cross flow mainly the strong-jet phenomenon, preliminary time-accurate high angles of attack simulation results will be presented.
Active Vibration Control of Aircraft Wings Modeled as Thin-Walled Composite Beams Using Piezoelectric Actuation
Authors: Yildiz Kaan , Eken Seher , Kaya Metin O.
Published: March 2015

In this study the closed-loop vibrational behavior of aircraft wing is investigated. The wing is modeled as a thin-walled composite beam with a diamond shaped cross-section. This beam model incorporates a number of non-classical effects such as material anisotropy, transverse shear deformation and warping restraint. Moreover, the directionality property of thin-walled composite beams produces a wide range of elastic couplings. In this respect, an anti-symmetric lay-up configuration i.e. Circumferentially Uniform Stiffness (CUS) is employed to generate coupled motion of transverse-lateral bending and transverse shear. The active feedback control is performed by using adaptive materials. The piezoelectric layers are symmetrically embedded in the host structure and the piezoactuator is spread over the entire beam span. As a result of this a boundary moment is induced at the beam tip and in this case, the control is achieved via the boundary moment feedback control yielding an adaptive change in the dynamical characteristics of the beam. the cases of proportional and velocity feedback control procedures are applied and the effect of ply-angle orientation on the fundamental frequencies are investigated and discussed.
Gesture Recognition for Control in Human-Robot Interactions
Authors: Reid Chris , Samanta Biswanath
Published: March 2015

In co-robotics applications, the robots must be capable of taking inputs from human partners in different forms, including both static and sequential hand gestures, in dynamic interactions for enhanced effectiveness as socially assistive agents. This paper presents the development of a gesture recognition algorithm for control of robots. The algorithm focuses on the detection of skin colors using monocular vision of a moving robot base where the inherent instability negates the effectiveness of methods like background subtraction. The algorithm is implemented in the open-source, open-access robotics software framework of Robot Operating System (ROS). The video feed from the camera is converted into several color spaces, including RGB and YCbCr. Pixels observed in the raw video feed as skin are randomly selected and their properties in each of the color spaces are recorded. A cylinder of infinite length is constructed out of the best fit line for both color spaces, and all points lying within both cylinders are accepted as a skin tone. The gesture recognition features are extracted from the filtered image and can be used for planning the motion of the robot. The procedure is illustrated using the on-board camera on an unmanned aerial vehicle (UAV).
Modeling and Workspace Analysis of Collaborative Advanced Fiber Placement Machine
Authors: Zhang Xiaoming , Xie Wen-Fang , Hoa Suong V.
Published: March 2015

The Advanced Fiber Placement (AFP) machines have brought significant improvement on the manufacturing of composite. However, the current AFP machines are not capable of handling some applications with more complex shapes. This paper presents a collaborative AFP machine which consists of a 6-RSS parallel platform, a 6-DOF manipulator and a spindle mounted on the platform to hold the mandrel. The collaborative modeling is built and simulated in SimMechanics/Matlab. The inverse kinematic models are established for trajectory planning. In addition, the workspaces of both parallel robot and collaborative AFP machine are analyzed using geometrical method and programmed in Solidworks. A simulation example for the manufacturing of a hemisphere is provided. The result shows that the collaborative AFP machine could enlarge the manufacture workspace, simplify the trajectory planning and enhance the productive efficiency.
Low Cost Experimental Vibration Analysis of a Cantilever Beam Under Base Excitation
Authors: Hassanpour Pezhman A. , Helmns Andrea J.
Published: March 2015

This paper presents the investigation of operational deflection shapes of vibration of a cantilever beam using a low-cost digital video camera, and by application of image processing techniques. The beam is uniform and under base excitation. The analytical model of the system is developed using dimensionless formulation. The analytical ODS’s are derived, and then compared with those found from experiment. The significance of this research is that it provides the researchers an inexpensive alternative tool for investigating the behavior of systems with low-frequency dynamics.
Design of Graphical User Interfaces for the Synthesis of Planar RR Dyads
Authors: Sundram Jugesh , Venkataramanujam Venkatesh , Larochelle Pierre
Published: March 2015

This article discusses the design and implementation of two Matlab graphical user interfaces (GUIs) for mechanism synthesis. The first GUI addresses the four location Burmester synthesis problem. The designer specifies the 4 locations that are used to generate the Burmester curves for these prescribed locations. The GUI enables the designer to interact with these curves and choose a pair of moving and fixed pivots forming an RR dyad. The second GUI addresses dimensional synthesis of RR dyads for hybrid motion generation tasks. Given a hybrid motion generation task, the designer can either pick the fixed or moving pivots and the corresponding pivots of an RR dyad is determined. In both the interfaces, the designer is provided with tools to specify tasks. The GUIs were designed with an objective to provide the designer with a simple workflow. Design case studies that illustrate the features and capabilities of each GUI are included.