bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluation of Fuel Economy and Emissions Reduction for a Motorcycle With Automatic Idling-Stop Device
Authors: Yu Chih-Hsien , Tseng Chyuan-Yow , Chuang Shiunn-Cheng
Published: February 2014

In an attempt to improve the fuel economy and reduce the exhaust emissions of motorcycles, some manufactures have developed commercialized motorcycles equipped with automatic idling-stop and go (AISG) functionality. Even though research efforts devoted to the idling-stop strategy have demonstrated its effectiveness, motorcycles equipped with the AISG device are not popular because the general public still has some concerns about them. This paper aims to evaluate the benefits and feasibility of a commercialized motorcycle with AISG functionality with regard to the public's concerns about fuel economy and emission problems during engine restart transients. In order to verify the accuracy of the analytical results and control for variable driver characteristics, a motorcycle chassis dynamometer was used to recreate the urban driving pattern. Furthermore, the feasibility of fuel-saving and emissions improvement by adjusting fuel-injection signal of the engine control unit (ECU) during engine restart operation was also evaluated. The experimental results showed that the addition of the fuel-injection modulation plus idling-stop strategy can improve the fuel economy rate by up to 12.2% and reduce carbon monoxide (CO) emission by up to 36.95% in comparison with the non-idling stop case.
Infiltration Velocity and Thickness of Flowing Slag Film on Porous Refractory of Slagging Gasifiers
Authors: Krishnaswamy Ramalakshmi , Kenneth Kaneko Tetsuya , Madhab Mazumdar Bishal , Rozelle Peter , Sridhar Seetharaman , Kuhlman John M.
Published: February 2014

Two analytical formulations that describe the fluid interactions of slag with the porous refractory linings of gasification reactors have been derived. The first formulation considers the infiltration velocity of molten slag into the porous microstructure of the refractory material that possesses an inherent temperature gradient in the direction of infiltration. Capillary pressures are assumed to be the primary driving force for the infiltration. Considering that the geometry of the pores provides a substantially shorter length scale in the radial direction as compared with the penetration direction, a lubrication approximation was employed to simplify the equation of motion. The assumption of a fully developed flow in the pores is justified based on the extremely small Reynolds numbers of the infiltration slag flow. The second formulation describes the thickness of the slag film that flows down the perimeter of the refractory lining. The thickness of the film was approximated by equating the volumetric slag production rate of the gasification reactor to the integration of the velocity profile with respect to the lateral flow cross-sectional area of the film. These two models demonstrate that both the infiltration velocity into the refractory and the thickness of the film that forms at the refractory surface were sensitive to the viscosity of the fluid slag. The slag thickness model has been applied to predict film thicknesses in a generic slagging gasifier with assumed axial temperature distributions, using slag viscosity from the literature, both for the case of a constant slag volumetric flow rate down the gasifier wall, and for the case of a constant flyash flux distributed uniformly over the entire gasifier wall.
Energy Redistribution Between the Mean and Pulsating Flow Field in a Separated Flow Region
Authors: Dol Sharul S. , Salek M. Mehdi , Martinuzzi Robert J.
Published: February 2014

One of the main features of the backward-facing step (BFS) low frequency pulsatile flow is the unsteadiness due to the convection of vortical (coherent) structures, which characterize the flow dynamics in the shear layer. The physics of the flow field is analyzed by looking at energy redistribution between the mean and pulsating flow field obtained via a particle image velocimeter (PIV) using the concept of a triple decomposition. The total fluctuating kinetic budget is calculated and discussed for a mean Reynolds number of 100 and for 0.035 ≤ St ≤ 2.19. The effects that these coherent structures have on the fluctuating kinetic energy production, dissipation, and transport mechanism are examined. The results provide insight into the physics of the flow and suggest reasons for vortex growth and decay. Fluctuating kinetic energy is generally produced at the separated shear layers and transported towards the core flow and then to the upper and lower walls where viscosity dissipates the energy. The remaining energy is transported streamwise and decays as it is convected downstream (St = 0.4 and 1 cases). It was also found that the pressure-velocity correlation diffusion plays a significant role in the transport of kinetic energy and Reynolds stresses, especially in the separated shear layer. More energy was dissipated at the walls for the high Strouhal number case St = 2.19 due to the transverse pressure diffusion term being increasingly dominant. This could be the reason why the convected primary vortices were much smaller in size and weaker with no upper wall vortices formed at this pulsation Strouhal number. The shear production for St = 0.035 was very minimal; thus, the vortices died down quickly even before the shedding could happen. Finally, the pressure-strain correlation term was found to be significant in redistributing the kinetic energy from u-component to v-component.
Study of Cylinder Charge Control for Enabling Low Temperature Combustion in Diesel Engines
Authors: Divekar Prasad , Asad Usman , Han Xiaoye , Chen Xiang , Zheng Ming
Published: February 2014

Suitable cylinder charge preparation is deemed critical for the attainment of a highly homogeneous, diluted, and lean cylinder charge, which is shown to lower the flame temperature. The resultant low temperature combustion (LTC) can simultaneously reduce the NOx and soot emissions from diesel engines. This requires sophisticated coordination of multiple control systems for controlling the intake boost, exhaust gas recirculation (EGR), and fueling events. Additionally, the cylinder charge modulation becomes more complicated in the novel combustion concepts that apply port injection of low reactivity alcohol fuels to replace the diesel fuel partially or entirely. In this work, experiments have been conducted on a single cylinder research engine with diesel and ethanol fuels. The test platform is capable of independently controlling the intake boost, EGR rates, and fueling events. Effects of these control variables are evaluated with diesel direct injection and a combination of diesel direct injection and ethanol port injection. Data analyses are performed to establish the control requirements for stable operation at different engine load levels with the use of one or two fuels. The sensitivity of the combustion modes is thereby analyzed with regard to the boost, EGR, fuel types, and fueling strategies. Zero-dimensional cycle simulations have been conducted in parallel with the experiments to evaluate the operating requirements and operation zones of the LTC combustion modes. Correlations are generated between air–fuel ratio (λ), EGR rate, boost level, in-cylinder oxygen concentration, and load level using the experimental data and simulation results. Development of a real-time boost-EGR set-point determination to sustain the LTC mode at the varying engine load levels and fueling strategies is proposed.
Characterization of Surface Integrity Produced by Sequential Dry Hard Turning and Ball Burnishing Operations
Authors: Grzesik Wit , Żak Krzysztof
Published: February 2014

This paper presents the state of surface integrity produced on hardened-high strength 41Cr4 steel after hard machining and finish ball burnishing. Surfaces machined by sequential machining processes were characterized using 2D and 3D surface roughness parameters. Moreover, detailed functionality of the generated surfaces was performed using a set of 3D functional roughness parameters. Among the characteristics of the surface layer, its microstructure, the distribution of microhardness and the residual stresses were determined. This investigation confirms that ball burnishing allows producing surfaces with lower surface roughness and better service properties than those generated by cubic boron nitride (CBN) finish hard turning operations.
Modeling, Simulation and Characterization of a Linear Shape Memory Actuator With Compliant Bow-Like Architecture
Authors: Scirè Mammano Giovanni , Dragoni Eugenio
Published: February 2014

The design of shape memory alloy (SMA) actuators typically compromises between force and stroke, the two properties being hard to achieve simultaneously. This paper presents a bow-like compliant SMA actuator aimed at improving the performance on both sides. Conceptually, the actuator is formed by two straight elastic beams hinged at the ends with an SMA wire pre-stretched in between. Heating of the alloy shortens the wire, which in turn makes the beams to buckle outward in a symmetric double-arched configuration. The transverse displacement of the beams amplifies the contraction of the wire while producing a favourable output force. The paper develops a simple, though accurate, analytical model of the actuator upon which a step-by-step design procedure is built. The numerical results for a case study are compared with the outcome of a finite element simulation.
An Investigation of Service-Oriented Shape Memory Actuator Systems for Resource Efficiency
Authors: Rathmann Christian , Czechowicz Alexander , Meier Horst
Published: February 2014

Nowadays companies working in the field of industrial applications realize that traditional electromagnets reach their technical limits. Additionally, there is an increasing awareness for resource-efficiency and safety, due to shortages in resources and rise in legal requirements. Furthermore customers demand more and more system solution, because of increased complexity in technical applications. Service-oriented shape memory actuator systems are an innovative approach that can help companies meeting these challenges and thus not only keep but enhance their competitiveness.

Therefore, this paper is focusing on the presentation of a service-oriented smart memory actuator system based on condition monitoring or reconfiguration by heat treatment. Hence an experimental actuator system is designed. This system is used to evaluate feasibility of condition monitoring to predict lifetime and the ability to reconfigure properties in use by heat treatment. Finally, an appropriate business model for service-oriented shape memory actuator systems is discussed.

First results of the project are presented within the paper as well as a business model draft for a service-oriented shape memory actuator system. Further studies should be done investigating the feasibility of remote heat treatment as well as developing applicable business models for shape memory actuator systems.
Steady State Crack Growth in Shape Memory Alloys
Authors: Hazar Selcuk , Zaki Wael , Moumni Ziad , Anlas Gunay
Published: February 2014

Shape memory alloys experience phase transformation from austenite to martensite around crack tip. When the crack advances, martensitic transformation occurs at the tip and the energy that goes into transformation results in stable crack growth like in the case of plastic deformation. In literature, there are studies on steady-state crack growth in elasto-plastic materials with small scale yielding around crack tip that use stationary movement methods similar to non-local algorithms. In this work, Mode I steady-state crack growth in an edge cracked Nitinol plate is modeled using a non-local stationary movement method. The Zaki-Moumni (ZM) constitutive model is utilized for this purpose. The model is implemented in ABAQUS by means of a user-defined material subroutine (UMAT) to determine transformation zones around the crack tip. Steady-state crack growth is first simulated without considering reverse transformation to calculate the effect of transformation on stress distribution in the wake region, then reverse transformation is taken into account. Stress distribution and transformation regions calculated for both cases are compared to results obtained for the case of a static crack.
Shear Vibration Property of Magnetically-Responsive Gels in Magnetically Open Looped System
Authors: Nasuno Hiroshi , Shibuya Yotsugi , Sodeyama Hiroshi , Sunakoda Katsuaki
Published: February 2014

This paper deals with dynamic shear deformation characteristics of magnetically-responsive (MR) gels under inhomogeneous magnetic fields. Magnetic particles as Fe-Si-Ni type which is generally known as permalloy, were dispersed in silicone gel to prepare the MR composite. An external magnetic field is applied only to one side of the MR gel by using magnetically open-looped circuit, and different excitation frequencies with constant shear strain amplitude is also applied to MR gels with each different thickness. The shear displacement-force relation of MR gel in open-looped circuit were observed, and mechanical properties such as storage and loss moduli were evaluated from experimental data. As a result, it is found that the characteristics change to a large extent depending on the applied magnetic field and the thickness of the MR gel.
Hysteresis Analysis of PLZT Actuator Based on the Photovoltaic Effect and the Viscoelastic Effect
Authors: Huang J. H. , Wang X. J. , Wang J.
Published: February 2014

Compared with the traditional actuators, the photostrictive actuators have huge advantages in applying in the hostile environments. The cantilever structure made of PLZT bimorph is used to increase the mechanical displacement because of the smaller photostrictive displacement of one PLZT patch. However, when one side of the PLZT bimorph was irradiated by the ultraviolet light with wavelength of 365nm, the response of the photodeformation is far slower than the photovoltage and the photocurrent, which prevents it from using in the high-frequency dynamic applications. In this study, a novel mathematical model of PLZT patch based on the photovoltaic effect and viscoelastic effect was proposed. And the tip deflection equation of PLZT bimorph was derived by the linear theory of viscoelasticity and constitutive relations of PLZT. And then the factors influencing the tip deflection were obtained by using the numerical analysis. Simultaneously, the hysteresis phenomenon of PLZT patch was explained.
Multiobjective Optimization of Trilayer Polypyrrole Conducting Polymer Actuators
Authors: Khalili Nazanin , Sun Yu-Chen , Naguib Hani E. , Kwon Roy H.
Published: February 2014

The main focus of this study is the optimization of a trilayer actuator comprising two layers of polypyrrole and a PVDF membrane core. Since the performance of these actuators is difficult to predict due to their mechanical and chemical properties, optimizing their output behavior such as the tip displacement and blocking force is of crucial importance for utilizing their full potentials and more significantly increasing predictability in their performance. For this purpose, two optimization techniques (multiobjective genetic algorithm and active set algorithm) have been carried out based on a developed mathematical model. Two nonlinear constrained equations representing the tip displacement and the blocking force are formulated and solved for a predetermined thickness of the PVDF core membrane. Both equations are subjected to a bound constraint and a nonlinear equality constraint. The output blocking force and the tip deformation act in a reverse manner and there is a trade-off between them. Accordingly, the results imply that there is no single solution to the problem and a range for each of the design variables should be determined so that there will be a sense of balance between the two objectives. Furthermore, the results obtained from the multiobjective optimization methodology have been verified experimentally.
Adaptive Tuned Dynamic Vibration Absorber With Variable Stiffness Property Using Magneto-Rheological Elastomers
Authors: Komatsuzaki Toshihiko , Iwata Yoshio , Ringe Hirofumi , Kawagoshi Keiji
Published: February 2014

A passive type dynamic vibration absorber offers advantages in reliability and simple constitution, however, the use of the absorber with fixed property is usually limited to harmonically excited case, where the damper is only effective for pre-determined narrow frequency range. Design of the damper following well-known optimal tuning theory could extend the effective frequency range, yet the damping performance remains at a certain amount. In this paper, the stiffness controllable elastomer composite known as Magnetorheological elastomer (MRE) is applied to the dynamic absorber whose natural frequency is tunable by the external magnetic field. MREs are first fabricated and their field-dependent properties are investigated. The MRE is then applied to a dynamic absorber along with stiffness switching scheme so that the vibration of 1-DOF structure is damped more effectively. Investigations show that the vibration of the structure can be fully reduced by the proposed dynamic absorber with variable stiffness functionality.
Dynamic Characterization of Biomimetic Artificial Hair Cells
Authors: Travis Jeffrey P. , Dunlap Myles D. , Leo Donald J. , Grant J. Wallace
Published: February 2014

The research presented in this paper investigates the relationship between fluid flow characteristics in an artificial cochlear environment and artificial hair cell sensor response. First, a lipid bilayer-based hair cell sensor is created to model the inner hair cells of the human cochlea. The artificial cochlear environment is then fabricated to recreate the pulsating fluid flow around the artificial inner hair cell stereocilia. Mechanical excitation creates sinusoidal fluid flows in the artificial cochlear environment at a range of frequencies determined by the response of the hair cell sensor in air. For excitation frequencies at and below 40 Hz, the response of the hair cell sensor is approximately equal to the control case having no bilayer. At these low frequencies, bilayer dynamics do not appear to lead to current generation. At frequencies at and above 70 Hz, and in the absence of an externally applied DC offset across the bilayer, the hair cell sensors featuring a bilayer generate up to double the RMS current. Therefore, for excitation frequencies at and above 70 Hz, bilayer dynamics play a significant role in hair cell sensor response. Further testing of the hair cell sensor shows that applying a DC offset across the bilayer increases the peak-to-peak sensor output by up to a factor of 80.
Feedback Controlled Bilayer Heating Within the Regulated Attachment Method
Authors: Taylor Graham , Sarles Andy
Published: February 2014

Synthetic lipid bilayers provide a cell-inspired environment for studying the functions of biomolecules. The regulated attachment method (RAM) is one method for forming liquid-supported lipid bilayers — known as droplet interface bilayers (DIBs) — that form at the interface of lipid-encased aqueous volumes in oil. While RAM allows for independent control of the aqueous phases on both sides of the membrane and provides a convenient way to control the size of the bilayer, previous studies utilizing this technique have been performed exclusively at room temperature. The goal of this research is to incorporate proportional-integral (PI) feedback control of temperature within the flexible RAM substrate with initial efforts focused on heating above room temperature. The proposed system includes a resistive etched-foil heating element and wire-type thermocouples for point-wise temperature measurement in standard RAM substrates. Open loop heating tests are used to map the magnitudes of steady state temperature distributions within the substrate and characterize the dynamic heating response. These tests show that a first-order heating model accurately describes transient temperature responses to heater power inputs. A one-probe configuration is found to provide measurements that are within <1°C of temperature measured at the bilayer region. The optimized probe configuration is used in PI feedback control, where the closed loop system is found to track the desired temperature to within +/−0.3°C. Experiments of temperature control with aqueous lipid droplets present permit electrical measurements of bilayer area without increasing background noise. Using this platform, we study the effect of temperature on the stability and size of a diphytanoyl phosphatidylcholine (DPhPC) lipid bilayer, and we observe that increasing the temperature of the bilayer from room temperature to 30°C results in a 30% decrease in the area of the membrane.
Toward Variable Recruitment Fluidic Artificial Muscles
Authors: Bryant Matthew , Meller Michael A. , Garcia Ephrahim
Published: February 2014

We investigate taking advantage of the lightweight, compliant nature of fluidic artificial muscles to create variable recruitment actuators in the form of artificial muscle bundles. Several actuator elements at different diameter scales are packaged to act as a single actuator device. The actuator elements of the bundle can be connected to the fluidic control circuit so that different groups of actuator elements, much like individual muscle fibers, can be activated independently depending on the required force output and motion. This novel actuation concept allows us to save energy by effectively selecting the size of the actuators on the fly based on the instantaneous required load, versus the traditional method wherein actuators are sized for the maximum required load, and energy is wasted by oversized actuators most of the time. This design also allows a single bundled actuator to operate in substantially different force regimes, which could be valuable for robots that need to perform a wide variety of tasks and interact safely with humans. This paper will propose this actuator concept and show preliminary results of the design, fabrication, and experimental characterization of three such bioinspired variable recruitment actuator prototypes.
A Minimally Invasive Cage for Spinal Fusion Surgery Utilizing Superelastic Hinges
Authors: Anderson Walter , Haberland Christoph , Elahinia Mohammad
Published: February 2014

A prototype cage implant for spinal fusion surgery has been designed and developed. Spinal fusion surgery is sometimes performed to alleviate low back pain. The cage implant is a spacer that sits in between two vertebrae to allow for bone growth and fusion, all while relieving compression of the spinal cord. The cage implant is minimally invasive in nature, utilizing embedded nitinol hinges as dual purpose actuators and assembly structural elements. The cage implant utilizes elliptical shaped nitinol hinge pins as actuators to allow the cage to be in a straightened before deployment and manipulate its shape to an oblong octagon once within the disc space. A new modeling technique was developed to aid with the design of the nitinol ellipses. The model is MATLAB based and accounts for the non Mises behavior of nitinol through a correction factor for mapping the effective stress and strain. A nitinol rod and an elliptical geometry were examined experimentally and show the robustness of the developed model. These experiments were conducted to design the nitinol hinges for the cage implant. The cage implant is made of two different materials, nitinol hinge actuators and the containing titanium structural segments. The nitinol hinge actuators are completely enclosed within the medical grade titanium segments through the use of selective laser sintering.
Uncertainty Quantification for Robust Control Design of Smart Material Systems
Authors: McMahan Jerry A. , Smith Ralph C.
Published: February 2014

The objective in robust control design is to provide mechanisms to achieve tracking or stabilization objectives in the presence of unmodeled dynamics. This is usually achieved by assuming worst case model discrepancies which can significantly degrade control authority if the uncertainty bounds are overly conservative. In this paper, we use uncertainty quantification techniques to construct densities for control outputs that can be used to derive optimal robust control designs. We illustrate the performance of these techniques in the context of systems with smart material actuators and sensors.
Simulation of Hydrogel Responsiveness to Blood Glucose
Authors: Suthar Kamlesh J. , Ghantasala Muralidhar K. , Mancini Derrick C.
Published: February 2014

This paper presents the results of our fully coupled, two-dimensional (2D) simulation of the swelling behavior of glucose-sensitive hydrogels at a constant glucose level with change in the surrounding pH. The model consists of a system of glucose-sensitive hydrogel and ionic fluid as a solvent. The hydrogel consists of two enzymes: glucose-oxidase and catalase, which are immobilized on the polymeric network. The surrounding solvent has certain level of glucose. The diffusion of glucose from a solvent and its reaction within the hydrogel are simulated using the Nernst-Planck equation. The local electrical charge is calculated by the Poisson’s equation, and deformation of the hydrogel is determined by the mechanical field equation. These equations are fully coupled and simulations are performed for varying pH and glucose concentrations. The glucose concentration was taken at 7.7mM (140mg/mL) and the pH is varied from 6.8 to 7.4. As glucose reacts with oxygen, gluconic acid is produced in the presence of glucose-oxidase. The formation of gluconic acid within the gel results in protonation and thereby causes the hydrogel expansion. The glucose level in the surrounding solution limits diffusion in the hydrogel. As the surrounding solution pH increases the available fixed charged for ionization increases, which results in an increase in maximum equilibrium swelling and gluconic acid as a product of the reaction. The gluconic acid production was found to be proportional to the change in pH. The gluconic acid decreases the internal pH of the hydrogel, which ultimately reduced the deformation of the gel.
Effects of Rapid Change in Temperature on Ultrasonic Guided Lamb Wave Propagation
Authors: Sivasubramanian Balaji , Kim Daewon
Published: February 2014

The usage of ultrasonic guided Lamb wave approach in structural health monitoring has been prevalent and proven to be an effective method. During flight, aircraft or spacecraft structures sometimes experience rapid temperature changes. The propagation of guided Lamb waves can be affected by these abrupt changes. In this paper, the effects of rapid temperature variation, due to which a sharp temperature gradient is achieved, on the propagation of guided Lamb waves through aluminum and composite beams are compared. The heating and cooling cycles for gradual temperature changes are firstly obtained for comparison. An abrupt change in the temperature is brought out by heating the beam to an elevated temperature and rapidly cooling it using liquid nitrogen. The design guidelines for the experimental setup used in the research are provided. The effects of rapid change in the temperature on the piezoelectric wafer active sensors (PWAS) are measured. Two different adhesives between the PWAS sensors and the beams are tested and the results obtained from the experiments are discussed.
Frequency Dependent Ion Rejection Properties of Active Nanoporous Membranes
Authors: Sundaresan Vishnu-Baba
Published: February 2014

Selective rejection of dissolved salts in water is achieved by large pressure gradient driven flows through tortuous structures and cylindrical nanopores. The flow rate through the membrane is dependent on the area of the membrane and pressure gradient that can be sustained by the membrane. The electrical power required for generating large pressure gradients increases the operational cost for desalination units and limits application of contemporary technologies in a wide variety of applications. Due to this limitation, small scale operation of these desalination systems is not economical and portable. Further, recently proposed desalination systems using carbon nanotubes and nanofluidic diodes have limited lifetime due to clogging and fouling from contaminants in feed water. In order to develop a desalination system that is not limited by cost, scale of operation and application, an active nanopore membrane that uses multiphysics interactions in a surface-functionalized hyperboloidal nanopore is developed. An active nanopore is a shape-changing hyperboloidal pore that is formed in a rugged electroactive composite membrane and utilizes coupled electrostatic, hydrodynamic and mechanical interactions due to reversible mechanical oscillations between the charged pore walls and dissolved ions in water for desalination. This novel approach takes advantage of the shape of the pore to create a pumping action in the hyperboloidal channel to selectively transport water molecules. In order to demonstrate the applicability of this novel concept for water desalination, the paper will use a theoretical model to model the ion rejection properties and flow rate of purified water through an active nanoporous membrane. This article examines the effect of the geometry of the nanopore and frequency of operation to reject dissolved ions in water through a multiphysics model. It is estimated that the neck diameter of the active nanopores is the most dominant geometrical feature for achieving ion rejection, and the flux linearly increases with the frequency of operation (between 2–50Hz). The threshold neck diameter of the nanopore required for achieving rejection from multiphysics simulation is observed to be 100nm. The flux through the membrane decreases significantly with decreasing diameter and becomes negligible at 10nm effective neck diameter.
Wear Reduction Through Piezoelectrically-Assisted Ultrasonic Lubrication
Authors: Dong Sheng , Dapino Marcelo J.
Published: February 2014

Ultrasonic vibration has been proven effective in reducing dynamic friction when superimposed onto the macroscopic relative velocity between two surfaces. This phenomenon is often referred to as ultrasonic lubrication. Piezoelectric materials can be employed to generate ultrasonic vibration. Typically, solid or fluid lubricants are employed to mitigate wear. However, in applications such as aerospace systems, which operate in particularly harsh environments, traditional lubrication methods are not always applicable. This paper investigates the relationship between friction force reduction and wear reduction in ultrasonically lubricated surfaces. A pin-on-disc tribometer is modified through the addition of a piezoelectric transducer which vibrates the contact between pin and disc. A piezo-actuator is installed to generate 22 kHz vibration in the direction perpendicular to the disc. Three different linear speeds are employed by changing rotation speeds of the disc and running time. Friction and wear metrics such as volume loss, surface roughness, friction forces and stick-slip effects are compared before and after application of ultrasonic vibration. Relationships between linear speed and friction reduction, stick-slip reduction, and wear reduction are analyzed.
Novel Two-Stage Electrical Energy Generators for Low and Variable Speed Rotary Machinery
Authors: Rastegar Jahangir , Murray Richard
Published: February 2014

A novel class of two-stage electrical energy generators is presented for rotary machinery and rocking platforms in which the input speed is low and varies significantly, even reversing. Applications include wind mills, turbo-machinery for harvesting tidal flows, floating platforms and the like. Current technology using rotary generators requires gearing or similar mechanisms to increase the input speed to make the generation cycle efficient. Variable speed-control mechanisms are also usually needed to achieve high mechanical to electrical energy conversion efficiency. In this paper, electrical energy generators are presented that can efficiently operate at very low and highly variable and even intermittent and reversing speeds without requiring gearing or other speed control mechanisms. The generators are very simple in design and can significantly reduce complexity and cost, especially those pertaining to maintenance and servicing. In addition, these new generators can expand the application of energy harvesting to much slower input speeds than current technology allows.

The primary novelty of this technology is the two-stage harvesting system. In these energy harvesting systems, input mechanical energy from the environment such as wind or ocean waves is stored in a primary sub-system (stage) as potential energy. When the level of potential energy reaches a certain predetermined level, it is released into a secondary sub-system (stage). The secondary sub-system converts the stored mechanical energy into electrical energy. The secondary sub-system is preferably designed as vibrating mass-spring type energy harvester to achieve relatively high and nearly constant natural frequency and use piezoelectric or magnet and coil type generators to convert stored mechanical energy of vibration to electrical energy.
Advanced Self-Healing Ceramics for Turbine Blade
Authors: Nakao Wataru
Published: February 2014

Advanced fiber reinforced ceramic composite having self-healing function (shFRC) has been developed. The composite includes the silicon carbide interlayer as healing agent at the interface between alumina fiber and alumina matrix. The healing agent interlayer caused the preferential fracture of the fiber/matrix interface and the interface fracture gave rise to the slip of the interface during crack propagation. Thereby the shFRC could exhibit a large deformation at the fracture and large fracture energy. Moreover, the high temperature oxidation of the healing agent made the interface delimitation rebounded by the formed oxide and the reaction heat. As a result, the maximum strength and the stiffness degraded by the interface delimitation could be recovered by the healing. Consequently, it was found that the shFRC containing the interlayer of the healing agent can survive the repeated crack propagation or initiation due to the large impact damage.
Integrated Sensor Concepts for Dielectric Elastomer Actuators
Authors: Maas Jürgen , Griese Martin , Hoffstadt Thorben
Published: February 2014

Actuators based on dielectric electroactive polymers (DEAP) use the electrostatic pressure to convert electric energy into strain energy. Besides this, they are also predestined for sensor applications to monitor the actual stretch state based on the deformation dependent capacitive-resistive behavior of the DEAP. Considering DEAP actuators for positioning applications, like stack- or roll-actuators, the actual position, length or stretch of the actuator is required for a precise control. Thus, integrated sensors made of DEAP can be used to determine the actual stretch state with sufficient accuracy and high dynamics on the one hand. On the other hand the electrical behavior of the DEAP transducer itself can be evaluated for the estimation of the stretch state representing a sensor-less concept. In this paper at first the state of the art of sensor-based and sensor-less concepts for determining the stretch state of DEAP transducers is presented. Afterwards the authors propose novel concepts for DEAP-based sensors integrated into stack- and roll-actuators. These concepts are compared with each other in terms of sensitivity, accuracy, dynamics and integration efforts for the realization. Finally, fundamental concepts, estimation algorithms and different approaches for monitoring the actual stretch state are presented based on the electrical parameters of a lossy DEAP transducer, which are suitable both for sensor-based and sensor-less concepts.
A Compliant Ankle-Foot Orthoses (AFO) Based on Multi-Axial Loading of Superelastic Shape Memory Alloys
Authors: GorzinMataee Morteza , Taheri Andani Masood , Elahinia Mohammad
Published: February 2014

This paper presents a novel actuation solution to address the drop foot disorder. The proposed actuator consists of a superelastic Nitinol rod with a variable torsional stiffness that is adjusted by the controlled application of an axial load. The superelastic SMA element enables the AFO to provide sufficient torque during dorsiflexion to raise the foot. The provided torque at the ankle joint assists the patient in walking more naturally and subsequently prevents further issues such as muscle atrophy.

By appraising experimental data of the human gait, ankle stiffness is assessed in order to compare ankle behavior for various walking speeds during the swing phase. The adjustable compliance concept for the AFO is then explained, followed by a description of the actuation mechanism and complex loading configuration. Numerical modeling is also presented for the superelastic element of the AFO under specified multiaxial torsion-tension loading. Simulations are performed in MATLAB and variable stiffness results are compared with experimental data for verification.
Frequency Tunable Isolator Based on Shape Memory Alloy for Effective Shock and Vibration Suppression
Authors: Jeong Ho-Kyeong , Lee Juho , Han Jae-Hung
Published: February 2014

A Shock and vibration isolator is widely used due to its simplicity and effectiveness. It attenuates vibration energy when the external excitation frequency is more than about 2 times its natural frequency, while the vibration around its natural frequency is generally amplified. However, an exciting frequency often varies so that it is difficult to avoid the vibration amplification. In particular, when these amplification phenomena occur in the low frequency domain, induced large vibration displacements degrade the structural integrity.

This paper introduces a novel frequency tunable isolator proposed by the present authors. The isolator uses SMA wires as actuator as well as the isolation materials. The isolator material is a compressed mesh washer isolator using the pseudoelasticity of SMA. Frequency tune of the isolator can be easily achieved through a simple electric circuit. Thus, this isolator can be widely applied to various vibration and shock environments such as in aircrafts and motor vehicles. Particularly, the detail design procedure is presented here for the adaptive shock isolator for launch vehicle in order to achieve both shock attenuation performance and avoidance of the vibration amplification. Launch vehicles experience severe dynamic environment during the flight phase. Specially, pyroshock generated from the several separation events could result in malfunctions of electric components and low frequency vibration below 100 Hz at the maximum dynamic pressure phase could reduce the structural integrity of payload. The resonant frequency of the isolator is selectively controlled in two modes by using an adaptive mechanical system with compressing the isolation materials. The isolator was successfully designed and various test results with frequency tuning are presented, in this paper.
Energy Harvesting From Arrays of Long Barium Titanate Nanowires
Authors: Koka Aneesh , Sodano Henry A.
Published: February 2014

In this paper, a piezoelectric nanoelectromechanical system (NEMS) is fabricated using newly developed ultra-long (∼45μm) aligned barium titanate (BaTiO3) nanowire (NW) arrays that exhibit piezoelectric behavior for harvesting mechanical vibrational energy. The novel BaTiO3 NW NEMS is fabricated to have resonance at frequencies below 500 Hz for efficient energy harvesting since ambient mechanical vibrations typically exists in the 1 Hz to 1 kHz range. The maximum AC power harvested from the BaTiO3 NEMS is evaluated by impedance matching at resonant frequency. In addition, NEMS energy harvester comprised of seedless solution grown aligned ZnO NW arrays is also fabricated and direct vibration excitation experiments are performed to determine the peak AC power at optimal load resistor. Here, we clearly report the superior power harvesting capability from long ferroelectric BaTiO3 NW arrays than semiconducting ZnO NWs for the same electrode area when excited with the same sinusoidal base acceleration of 1g RMS at resonant frequency.
Coupled Modeling and Optimization of Piezocomposite Wings
Authors: Bilgen Onur , Friswell Michael I. , Taqiuddin Mohammed
Published: February 2014

A coupled electro-aero-mechanical modeling and optimization scheme for two solid-state piezocomposite variable-camber wing concepts is presented. The proposed concepts employ a continuous inextensible surface, simple boundary conditions and surface bonded piezoelectric actuators. The partially-active surfaces are designed to have sufficient bending stiffness in the chordwise and spanwise directions to sustain shape under aerodynamic loading. In contrast, the in-plane stiffness is relatively high; however the necessary deformations that are required to change the aerodynamic response can still be attained while maintaining the surface perimeter constant. Coupled with the continuous boundary conditions and the spar structure, the proposed concepts can achieve significant change in aerodynamic response quantified in terms of lift coefficient and lift-to-drag ratio under aerodynamic loading. A coupled analysis of the fluid-structure interaction is employed assuming static-aeroelastic behavior which allows the realization of designs that can sustain aerodynamic loads. Two prototypes are briefly presented.
Design Modification of a Passive Tip-Leakage Control Method for Axial Turbines: Linear Cascade Wind Tunnel Results
Authors: Benoni Albert , Willinger Reinhard
Published: February 2014

Tip-leakage losses can contribute up to one third of the overall losses in unshrouded axial turbine blades. A passive tip-leakage flow control method is used to reduce the tip-leakage loss. Taking into account a modified discharge coefficient model, an inclination of the injection against the tip-leakage flow direction is said to have an even better effect on reducing the tip-leakage loss. To prove the effect, linear cascade measurements have been carried out at three different gap widths from 0.85% to 2.50% chord length. The used geometry is an up-scaled turbine blade tip cross section with weak turning. A single blade is fitted with an injection channel which is inclined by 45° against the tip-leakage flow direction. The flow field of the modified blade was measured 0.31 axial chord length downstream of the cascade using a pneumatic five-hole probe. The tip-leakage loss is reduced by passive tip-injection and further by inclined injection. The reduction can be significant at small gap widths. Detailed results are presented for a gap width of 1.40% chord length.
Physics Almost Saved the President! Electromagnetic Induction and the Assassination of James Garfield: A Teaching Opportunity in Introductory Physics
Authors: Overduin James , Molloy Dana , Selway Jim
Published: February 2014

Electromagnetic induction is probably one of the most challenging subjects for students in the introductory physics sequence, especially in algebra-based courses. Yet it is at the heart of many of the devices we rely on today. To help students grasp and retain the concept, we have put together a simple and dramatic classroom demonstration that combines sight and sound with a compelling personal story from U.S. history. Other classroom activities dealing with induction have been discussed in this journal,1–4 but we believe that this one will be especially likely to attract and retain student interest, particularly in courses geared toward medical, biological, and other non-physics majors.
Physics Back in TIME
Authors: Korsunsky Boris
Published: February 2014

Recently, I came into possession of an unusual item: a collection of 1928 TIME magazines. I began flipping through the pages out of sheer curiosity—and was soon astonished by the scale and the depth of their physics coverage. Back then, TIME had a special “Science” section in almost every issue and devoted quite a bit of space to the events that would hardly be mentioned in any popular magazine these days. Some of them were fleeting and merely curious, some truly timeless. Many of the articles and notes were devoted to physics: the people, the discoveries, the inventions, the conventions. I found the reading both entertaining and enlightening and would like to offer a sampler here.1 I hope that these little tidbits of history will lighten up the classroom discussions and help inspire your students by reminding them that physics is a dynamic, ever-changing field to which they may well contribute one day. I have found that my own students love it when a little bit of history is brought up; it always generates interesting questions and seems to spark the students' interest in the topic.
The Acoustically Driven Vortex Cannon
Authors: Perry Spencer B. , Gee Kent L.
Published: February 2014

Vortex cannons have been used by physics teachers for years, mostly to teach the continuity principle. In its simplest form, a vortex cannon is an empty coffee can with a hole cut in the bottom and the lid replaced.1 More elaborate models can be purchased through various scientific suppliers under names such as “Air Cannon”2 and “Airzooka.”3 We will briefly discuss the uses of a vortex cannon in teaching and a new type of vortex cannon for teaching.
American Automobile and Light Truck Statistics Update
Authors: Feldman Bernard J.
Published: February 2014

Given that transportation is an essential topic in any Physics and Society or Energy course, it is necessary to have useful statistics on transportation in order to have a reasoned discussion on this topic. And a major component of the transportation picture is the automobile. This paper presents updated transportation statistics for American automobile and light truck usage. These data are a continuation of the original statistics presented in my paper “A Physicist's View of the Automobile Engine,” published almost 10 years ago.1
Quantized Algebra I Texts
Authors: DeBuvitz William
Published: February 2014

I am a volunteer reader at the Princeton unit of “Learning Ally” (formerly “Recording for the Blind & Dyslexic”) and I recently discovered that high school students are introduced to the concept of quantization well before they take chemistry and physics. For the past few months I have been reading onto computer files a popular Algebra I textbook,1 and I was surprised and dismayed by how it treated simultaneous equations and quadratic equations. The coefficients are always simple integers in examples and exercises, even when they are related to physics. This is probably a good idea when these topics are first presented to the students. It makes it easy to solve simultaneous equations by the method of elimination of a variable. And it makes it easy to solve some quadratic equations by factoring. The textbook also discusses the method of substitution for linear equations and the use of the quadratic formula, but only with simple integers.
Equations for description of nonlinear standing waves in constant-cross-sectioned resonators
Authors: Bednarik Michal , Cervenka Milan
Published: February 2014

This work is focused on investigation of applicability of two widely used model equations for description of nonlinear standing waves in constant-cross-sectioned resonators. The investigation is based on the comparison of numerical solutions of these model equations with solutions of more accurate model equations whose validity has been verified experimentally in a number of published papers.