bluuebunny/crossref_metadata_2025 huggingface dataset:
Investigation of the Optimal Injection Conditions for a PCCI Diesel Engine
Authors: Kim Yungjin , Park Sangki , Lee Kihyung
Published: July 2013

Premixed charge compression ignition (PCCI) engines have the potential with their attractive advanced combustion process to achieve a more homogeneous mixture and a lower peak combustion temperature resulting in both lower nitrogen oxides (NOx) and diesel particulate matter (PM) emissions. In this study, the spray characteristics for a PCCI engine according to various injection conditions were introduced and then the effects of injection strategies such as injection angles, injection timings and times on combustion and emissions were studied for a single cylinder PCCI engine using early multiple injections first. Add more, a method of early-main type split injection was used for a 4-cylinder PCCI engine and the effects of injection conditions on the combustion and emission characteristics were investigated. Finally flame visualization tests were performed to validate the result obtained from the engine test.

The experimental results showed that the mixture formation, indicated mean effective pressure (IMEP), and emission characteristics were dominantly affected by the injection conditions and the multiple injection method resulted in higher IMEP and still low smoke level characteristics. It appeared that more homogeneous mixture could be formed with decreasing of spray penetration and increasing of fuel evaporation rate for the early multiple injections. In case of the split injection, both injection timing and injected fuel ratio of the early and main injection largely affected engine combustion and emission characteristics. From the results, as the early injection rate increased premixed combustion was activated, on the other hand, as the main injection rate increased conventional diesel combustion was activated, therefore suitable split injection conditions could be selected for the 4-cylinder PCCI engine.
Dynamic Characteristic Analysis and Parameter Estimation for a Thermal Plant
Authors: Miyamoto Yuichi
Published: July 2013

A thermal plant as a controlled system has many state parameters, which cannot be measured directly in many cases. The control efficiency can be improved by applying estimated parameters to the control of the plant. A fluidized-bed incinerator is not constant in the quantity and quality of the feed refuse, which is the fuel, and combustion control is difficult owing to the rapidity of completion of combustion. However, it is thought to be possible to improve the efficiency of CO control and NOx control drastically if the state parameters such as the combustion rate on the upper bed site and the bed site, and the effective air ratio are known.

This paper proposes a method that estimates these state parameters by means of sensor outputs such as temperature, air flow rate, and cooling water rate, using dynamic characteristic analysis and neural networks. This paper also shows that it is possible to estimate the state parameters of an actual incinerator. Further, it is shown that the generalization of parameters estimation equations enables the application of the method to other plants.
The Design and Implementation of High Pressure Rectangular Diaphragm Sensor Based on MEMS Technology
Authors: Niu Zhe , Zhao Yulong , Tian Bian
Published: July 2013

This paper describes the design and fabrication of a piezoresistive high-pressure rectangular sensor which will be used in the petrochemical industry field. The stress distribution of the piezoresistance on the membrane was analyzed by the Finite Element Method through the ANSYS software. The piezoresistance was fabricated on SOI wafers by the MEMS bulk-micromachining technology and the silicon substrate was bonded with the Pyrex 7740# glass by the anodic bonding technology. The linearity, sensitivity, repeatability and accuracy of the fabricated result were 0.3%, 1.109mV/MPa, 0.41% and 0.57%, respectively. This type of microstructure sensor has advantages of high sensitivity, linearity and accuracy. Meanwhile, the sensor has a wide measurement range because of the rectangular membrane. The piezorsistive high pressure rectangular diaphragm sensor offers several advantages such as, high sensitivity, linearity and accuracy, and additionally, the wide measurement range of the sensor will guarantee its great applications in the petrochemical industry fields.
A New Composite Trajectory Method for Motion Accuracy Measurement of 3-Axis Machine Tools
Authors: Du Zhengchun , Yang Jianguo , Liang Steven Y.
Published: July 2013

Geometric motion error measurement has been considered as an important task for accuracy enhancement and quality assurance of NC machine tools and CMMs. In consideration of the disadvantages of traditional measuring methods, such as Laser interferometer and Double Ball Bar method, a new measuring method for motion accuracy of 3-axis NC equipments based on composite trajectory including circle and non-circle (straight line and/or polygonal line) is proposed. The principles and techniques of the new measuring method are discussed in detail. 8 feasible measuring strategies based on different measuring groupings are summarized and optimized. The experiment of the most preferable strategy is carried out on the 3-axis CNC vertical machining center Cincinnati 750 Arrow by using cross grid encoder. The whole measuring time of 21 error components of the new method is cut down to 1–2 h because of easy installation, adjustment, operation and the characteristics of non-contact measurement. Result shows that the new method is suitable for ‘on machine’ measurement and has good prospects of wide application.
Optimal Electric Power Management in a Residential Building Using Photovoltaic and Storage Battery
Authors: Demizu Tsukasa , Umetani Shunji , Morita Hiroshi
Published: July 2013

We consider the electric power management system facilitated the photovoltaic and storage battery. The total energy cost is derived by solving 0-1 mixed integer programming problem for several scenarios.
Motion Capture of Fastening Operation Using Wiimotes for Ergonomic Analysis
Authors: Zhu W. , Daphalapurkar C. P. , Puthenveetil S. Chirayil , Leu M. C. , Liu X. F. , Chang A. M. , Gilpin-Mcminn J. K. , Wu P. H. , Snodgrass S. D.
Published: July 2013

This paper presents an application of a Wii Remote (Wiimote) based, low-cost motion capture system for digital human simulation and ergonomic analysis of a fastening operation. The system includes a low-cost infrared (IR) based motion capture system developed using Wiimotes. A portable stereo vision system was used to capture the operator’s movements while performing a fastening operation during the assembly of an aircraft fuselage on the factory floor. IR LEDs mounted on the worker’s body served as markers. The captured motion data was used to generate a simulation of the operator’s arm movements and to perform ergonomic analysis with the help of digital human modeling software, Siemens Jack.
Robust Control Design of a Single Degree-of-Freedom Magnetic Levitation System by Quantitative Feedback Theory
Authors: Tian Feng , Nagurka Mark
Published: July 2013

A magnetic levitation (maglev) system is inherently nonlinear and open-loop unstable because of the nature of magnetic force. Most controllers for maglev systems are designed based on a nominal linearized model. System variations and uncertainties are not accommodated. The controllers are generally designed to satisfy gain and phase margin specifications, which may not guarantee a bound on the sensitivity. To address these issues, this paper proposes a robust control design method based on Quantitative Feedback Theory (QFT) applied to a single degree-of-freedom (DOF) maglev system. The controller is designed to successfully meet the stability requirement, robustness specifications, and bounds on the sensitivity. Experiments verify that the controller maintains stable levitation even with 100% load variation. Experiments prove that it guarantees the transient response design requirements even with 100% load change and 39% model uncertainties. The QFT control design method discussed in this paper can be applied to other open-loop unstable systems as well as systems with large uncertainties and variations to improve system robustness.
A Scheduling Method With Considering Nesting for Sheet Metal Processing
Authors: Sakaguchi Tatsuhiko , Murakami Tatsuro , Fujita Shohei , Shimizu Yoshiaki
Published: July 2013

In sheet metal processing, several parts are cut from one sheet metal by punching process. Before punching process, layout of parts is decided by the nesting. If the parts are arranged as compactly as possible into one sheet metal, the waste of raw materials can be reduced. Therefore, the nesting is essential for optimizing the layout of parts. However, if the nesting is executed without considering the following manufacturing processes, there cause various inefficiencies all over the processes. Therefore, the nesting and the scheduling should be considered simultaneously for the efficient manufacturing. With this point of view, in this study, we propose an integrated method in terms of scheduling and nesting. Moreover, we verified the effectiveness of the proposed method through some computational experiments.
A Basic Study on a Highly Distributed Simulation of Manufacturing Systems Under the Ubiquitous Environment
Authors: Fujii Susumu , Fujii Nobutada , Tsumaya Akira , Iwamura Koji , Morinaga Eiji , Inoue Tatsuo , Mariyama Toshisada
Published: July 2013

This study reports a new simulation paradigm devised to simulate manufacturing systems in its real operational stage. The objective manufacturing system is supposed to be under ubiquitous environment; in other words, all machines and equipments constituting a real manufacturing system are all equipped with intelligent devices and are connected to an information network. In the framework of the proposed simulation method, the simulation model is not built on one computer as is done in the conventional simulation, but is built on the network by integrating the intelligent devices. Each devise with properly embedded simulation functions plays as a simulation agent representing a resource or an entity in the conventional simulation model. This paper discusses the simulation functions required to each device to form a discrete event simulation system. The time management of the simulation and the event processes in the new simulation paradigm are described.
Energy Analysis of Machining and Machining Facilities Based on the Micro-Factory Concept
Authors: Wentz John E. , Coleman Andrew J.
Published: July 2013

The micro-factory concept has gained wide support and acceptance based on the ability of small machine tools to accomplish the same tasks as traditionally sized machine tools while using a fraction of the space. Although it is frequently mentioned that a micro-factory is an energy saving endeavor, there is a dearth of hard data on how much energy is actually saved.

The intent of this report is to quantify the difference in energy consumed in a micro-factory and a macro-factory though experimentation with a micro- and a macro-mill. This quantification allows for the potential of unit life cycle analyses to be performed in the future. A fluidic channel was machined in workpieces of aluminum and steel by both micro- and macro-mills under a variety of machining conditions and the recorded data has been analyzed to this end. The variables investigated were the spindle speed, the mill type, and the material the cutting process was performed on. The conclusions reached through experimentation were that the micro-mill used between 13.5% and 21.7% of the energy used for the macro-mill.

Additionally the energy differences in climate control were investigated for comparable macro- and micro-factories. The mock macro-factory used for this analysis was three times the size of the micro-factory. Due to the larger size of the macro-building, the climate control energy usages were also about three times as high as in the micro-building.
Optimization by Pre-Assignment of Processes for Re-Entrant Flowshop Scheduling Problem
Authors: Hino Rei , Osada Tomoya
Published: July 2013

A new optimization procedure for a re-entrant flowshop scheduling problem is proposed to plan a medium sized production schedule by mixed integer programming. Flow time is an index used to evaluate production work-in-process. The flow time is calculated from the total required cycle terms after a feasible schedule is planned. In the present paper, the reverse procedure is performed: the total cycle term is assumed before the scheduling, and the feasible schedule is planned under the assumed terms. The assumption of the total cycle term restricts the pre-assignment of every process into a corresponding cycle term. Therefore some pre-assignments never yield a feasible schedule and are eliminated from the evaluation. Methods for the assumption of the total cycle terms and for the examination of the pre-assignment of the processes are described here. The amount of times required to plan the optimal schedule is evaluated for different sizes of problems in order to validate the proposed procedures.
The Hybrid Approach of LCO and SA to Solve Job-Shop Scheduling Problem
Authors: Tamura Yasumasa , Suzuki Ikuo , Yamamoto Masahito , Furukawa Masashi
Published: July 2013

A Job-shop Scheduling Problem (JSP) is one of the combinatorial optimization problems. JSP appears as a basic scheduling problem in many situations of a manufacturing system and many methods for JSP have been invented. This study examines two effective methods, SA and LCO, for JSP and propose a hybrid method based on them. As a result of the experiments, the proposed method can find a good solution with short computational time. And the proposed method can hold the variance of the solutions less than the fundamental methods. Summarizing this study, the proposed method can find a good solution efficiently and stably.
A Robust Wheel Interface With a Novel Adaptive Controller for Computer/Robot-Assisted Motivating Rehabilitation
Authors: Theriault Andrew R. , Nagurka Mark L. , Johnson Michelle J.
Published: July 2013

TheraDrive is an effective system for post-stroke upper extremity rehabilitation. This system uses off-the-shelf computer gaming wheels with force feedback to help reduce motor impairment and improve function in the arms of stroke survivors. Preliminary results show that the TheraDrive system lacks a robust mechanical linkage that can withstand the large forces exerted by patients, and it lacks a patient-specific adaptive controller to deliver personalized therapy. It is also not capable of delivering effective therapy to severely low-functioning patients. A new low-cost, high-force haptic robot with a single degree of freedom has been developed to address these concerns. The resulting TheraDrive consists of an actuated hand crank with a compliant transmission. Actuation is provided by a brushed DC motor, geared to output up to 23 kgf at the end effector. To enable a human to interact with this system safely, a special compliant element was developed to double as a failsafe torque limiter. A set of strain gauges in the handle of the crank are used to determine the interaction forces between human and robot for use by the robot’s impedance controller. The impedance controller is used to render a one-dimensional force field that attracts or repels the end effector from a moving target point that the human must track during therapy exercises. As exercises are performed, an adaptive controller monitors patient performance and adjusts the force field accordingly. This allows the robot to compensate for gravity, variable mechanical advantage, limited range of motion, and other factors. More importantly, the adaptive controller ensures that exercises are difficult but doable, which is important for maintaining patient motivation. Experiments with a computer model of human and robot show the adaptive controller’s ability to maintain difficulty of exercises after a period of initial calibration.
LQ-Based Trajectory Tracking of Robotic Manipulators With “Near” Dynamically Feasible Time-Optimal Trajectory
Authors: Reynoso-Mora Pedro , Tomizuka Masayoshi
Published: July 2013

In this paper we study the trajectory tracking of robotic manipulators using LQ methods. We also present the development of an algorithm that generates “near” dynamically feasible time-optimal trajectories with complete dynamics model, which incorporates both Coulomb and viscous friction. It is shown how to incorporate the viscous-friction term through a convex relaxation of the original non-convex formulation. Viscous friction is traditionally ignored in all existing related formulations due to the intractability in solving the non-convex problem. As a case study, the methodology is applied to a 6-DOF industrial manipulator.
A Pulsed-Biasing Strain Gauge Measurement System for Wireless Sensing Applications
Authors: Lee Guan-Liang , Chen Jau-Horng , Li Kuan-Ming
Published: July 2013

This paper presents a pulsed-biasing strain gauge measurement system for wireless sensing applications. The use of pulsed-biasing on the strain gauge can reduce the power consumption of the sensor, which is crucial for low-power wireless sensors. Moreover, without using a constant bias current, power dissipated on the resistive bridge that includes the strain gauge can be reduced. Such reduction can also reduce measurement errors from an increased strain gauge temperature. A strain gauge wireless sensor was constructed using commercially available components. Measurement results show that the pulsed-biasing technique can be implemented with a duty cycle down to around 40% with negligible measurement error at a data rate of 32 Hz. The power saved is equivalent to an increased operation time of 50%.
Approach to Sustainable Smart Town and Role of International Standardization
Authors: Nomura Junji , Morikura Susumu , Tada Shinya
Published: July 2013

Sustainable Smart Town (SST) scheme which utilizes networking of energy and information is receiving much attention as a way of stable energy supply and efficient operation in each region and country. SST consists of Smart Grid to supply energy efficiently and energy efficient buildings such as smart homes, condominiums, stores and factories. In addition, new service such as Demand Response Service which takes advantage of networking is beginning to appear in the market.

This paper introduces outline of several SST pilot projects, energy consumption reduction in office building, demand response in existing residential house and information security system for facilities. It also mentions the role and future prospect of International Standardization to realize the safe, secure, comfortable and convenient SST.
Adaptive Control of Nonminimum Phase Systems Using Sensor Blending With Application to Launch Vehicle Control
Authors: Balas Mark J.
Published: July 2013

The goal of this paper is to investigate the use of a very simple direct adaptive controller in the guidance of a large, flexible launch vehicle. The adaptive controller, requiring no on-line information about the plant other than sensor outputs, would be a more robust candidate controller in the presence of unmodeled plant dynamics than a model-based fixed gain linear controller. NASA’s seven-state FRACTAL academic model for ARES I-X was employed as an example launch vehicle on which to develop the controller.

To better understand the difficult dynamic issues, we started with a simplified model that incorporated the inherent instability of the plant and the nonminimum phase nature of the dynamics: an inverted pendulum with an attachable slosh tank. We formulated controllers for this simplified plant with slosh dynamics using control algorithms developed only on a reduced–order model consisting of the rigid body dynamics without slosh. The controllers must be designed to reject three different persistent input disturbances: persistent pulse, step, and sine. We assumed that only position feedback was available, and that rates would have to be estimated.

For comparison, a fixed gain linear controller was developed using the well-known Linear Quadratic Gaussian methodology employing state estimation to obtain rate estimates. For a stable adaptive controller, we used direct adaptive control theory developed by Balas, et al. For this theory we need CB > 0 and a minimum-phase open-loop transfer function. We employed a new transmission zero selection method to develop a blended output shaping matrix which would satisfy these conditions robustly. We used approximate differentiation filters to obtain rates for the adaptive controller. Again for comparison, we redesigned the LQG controller to use the same blended output matrix and filters.

Following the work on the pendulum, the same method was applied to develop an adaptive controller for the FRACTAL launch vehicle model. An adaptive controller stabilizes a rigid body version of FRACTAL over a very long timeline while exceeding all reasonable state and output limits.
Robust Adaptive Control of Mildly Nonlinear Systems With Time Varying Input/Output Delays
Authors: Nelson James P. , Balas Mark J. , Erwin Richard S.
Published: July 2013

Many systems must operate in the presence of delays both internal to the system and in its inputs and outputs. In this paper we present a robustness result for mildly nonlinear systems. We use this result to show that, for small unknown time varying input delays, a simple adaptive controller can produce output regulation to a neighborhood with radius dependent upon the size of an upper bound on the delay. This regulation occurs in the presence of persistent disturbances and the convergence is exponential. We conclude with an example to illustrate the behavior of this adaptive control law.
Wave Propagation in Multi-Layered Elastic Beam
Authors: Unal Ahmet , Wang Gang
Published: July 2013

In this paper, a spectral finite element model (SFEM) is developed for an n-layered elastic beam and subsequently used to investigate its dynamic response and wave propagation characteristics. Each layer of the beam is idealized by a Timoshenko beam, in which shear deformation as well as rotational inertia are included. This higher order theory is critical to capture high frequency response of the multi-layered beam structures. Semi-analytical solutions were determined for the governing equations in order to construct the SFEM. Our frequency predictions were validated by the results of two and three-layer beams in the literature and good correlations were achieved. Fewer elements were used in our SFEM compared to conventional finite element based approaches, which substantially benefits the ultrasonic frequency simulations. Wave propagation responses were calculated for a two-layer beam, in which a notch in the top layer was assumed to represent the damage case. Wave reflection from the notch was observed to indicate the existence of damage. This newly developed SFEM can be served as a platform to conduct comprehensive simulations in order to capture wave propagation characteristics in multi-layered beam structures.
Modeling the Diluent Effect on Streaming Current for Ionic Polymer Transducers in Shear
Authors: Zangrilli Ursula T. , Weiland Lisa M.
Published: July 2013

Ionic Polymer Transducers (IPTs) are devices that exhibit superior charge sensing capabilities. Further, they can produce an electric signal in any mode of deformation. These sensors can be manufactured with various forms of diluent. Experimental results indicate that both the type and amount of the diluent in the IPT make a difference on the strength of the electrical current output. The streaming potential hypothesis is currently the only way to explain the existence of a electrical current in shear deformation. This work expands on a model previously presented to test the model’s ability to determine the effect of diluent variation and amount of diluent uptake.
Design of Bend-and-Sweep Compliant Mechanism for Passive Shape Change
Authors: Tummala Yashwanth , Frecker Mary , Wissa Aimy , Hubbard James E.
Published: July 2013

Contact aided compliant mechanisms are a class of compliant mechanisms where parts of the mechanism come into contact with one another during motion. Such mechanisms can have nonlinear stiffness, cause stress-relief, or generate non-smooth paths. New contact aided compliant mechanisms called bend-and-sweep compliant mechanisms are presented in this paper. These bend-and-sweep mechanisms are made up of compliant joints which are alternately located in two orthogonal directions, and they also exhibit nonlinear stiffness in two orthogonal directions. The stiffness properties of these mechanisms, in each direction, can be tailored by varying the geometry of the compliant joints. One application of these mechanisms is in the passive wing morphing of flapping wing UAVs or ornithopters. A design study is conducted to understand the effect of hinge geometry on the deflections and maximum von Mises stress during upstroke and downstroke. It is shown that the bend-and-sweep compliant elements deflect as desired in both the bending and sweep directions.
Control of Oscillations of a Wing Subjected to 3D Unsteady Subsonic Aerodynamic Loads Using Piezoelectric Actuators
Authors: Mirmohammadi Tahereh , Misra Arun K. , Mateescu Dan
Published: July 2013

In the recent years, using piezoelectric material as sensors and actuators has drawn significant attention in vibration analysis and control of structures. In the present paper, bonded piezoelectric sensors and actuators have been used to control the aeroelastic oscillations of a cantilever wing under the effects of three-dimensional unsteady subsonic aerodynamic loading. An aerodynamic model using a numerical panel method is developed and validated to calculate the three-dimensional unsteady aerodynamic loading and finite element formulation is applied to model the wing structure as a cantilever plate undergoing small transverse oscillations. The structural and aerodynamic models are combined to simulate the aeroelastic oscillations and interchange the data simultaneously. An active feedback control method to suppress the oscillations is presented and investigated. Finally, an analysis is performed to examine the effects of actuator placement on the wing surface in suppression of oscillations.
Vibration Sensing and Energy Harvesting Using Ultra-Long Vertically Aligned Array of Barium Titanate Nanowires
Authors: Koka Aneesh , Sodano Henry A.
Published: July 2013

In this paper, novel ultra-long aligned array of Barium Titanate (BaTiO3) nanowires (NWs) was used to fabricate piezoelectric sensors and investigate their vibration sensing and energy harvesting potential. The acceleration sensing characteristics of the piezoelectric BaTiO3 NWs based sensor was presented by conducting vibration excitation experiments induced from an electromagnetic shaker. Two different top electrode configurations which include a melted Indium and a short cantilever Indium beam located over the BaTiO3 NWs surface were utilized to study the acceleration sensing and energy harvesting scope respectively. The results shown validate their excellent energy conversion capabilities and demonstrate linear behavior over a wide frequency spectrum which elucidates their potential to be developed as advanced sensors and high efficiency vibrational energy harvesting devices.
Modeling of a Shape Memory Alloy Circular Bar Under Combined Axial-Torsional Loading
Authors: Taheri Andani Masood , Alipour Amin , Eshghinejad Ahmadreza , Elahinia Mohammad
Published: July 2013

In this paper, a semi-analytical analysis of the pseudoelastic response of shape memory alloy rods and tubes subjected to combined axial and torsional loading is proposed. A three-dimensional phenomenological SMA constitutive model is simplified to obtain the corresponding two-dimensional constitutive relations. The rod is partitioned into a finite number of narrow annular regions and the equilibrium equations are found in each annular region for both loading and unloading paths. Several numerical examples are presented to demonstrate the efficiency of the proposed method, and the results are compared with three-dimensional finite element simulations.
Helicopter Rotor Blade Chord Extension Morphing Using a Centrifugally Actuated von-Mises Truss
Authors: Moser Patrick , Barbarino Silvestro , Gandhi Farhan
Published: July 2013

Previous studies have shown that chord extension morphing over a spanwise section of helicopter rotor blades can reduce main rotor power requirement in stall-dominant flight conditions while at the same time being able to increase the maximum gross weight, altitude, and flight speed capability of the aircraft. This study examines a centrifugally driven, fully passive chord morphing mechanism for helicopter rotor blades. It is based on a von-Mises truss situated aft of the leading-edge spar, connected to a rigid extension plate which deploys through a slit in the trailing-edge. When the rotor RPM increases beyond a critical value the chordwise component of centrifugal (CF) force on the von-Mises truss and plate assembly results in the deployment of the plate beyond the slit in the trailing edge, effectively increasing chord length. On reducing the RPM, a retraction spring pulls the plate back within the confines of the blade. This study presents the design process, iterations and the final design solution for a configuration that undergoes 20% chord extension. A prototype was fabricated and tested on the bench-top as well as on a rotor test stand at rotational speeds simulating 70% full-scale CF loads. The test results demonstrate that the concept works. However, effects such as friction lead to higher force (or RPM) requirements for deployment than predicted by simulation, and are present during retraction as well. The effects are more pronounced in the high CF field in the rotor test.
Sensorless Control of SMA Using Seebeck Voltage
Authors: Malladi Sriram V. V. N. , Tarazaga Pablo A.
Published: July 2013

Active research of SMA has presented the measurement of thermoelectric properties as a useful and a potential tool in the study of phase transformations. The Seebeck coefficient is sensitive to the martensitic transformation behavior of SMA and can potentially be used to determine the state of Martensitic transformation of a SMA. The combination of Shape Memory Alloy having a positive Seebeck coefficient and Constantan with a negative Seebeck coefficient (−35 μV/K) is a suitable thermocouple pair to measure temperature. This relation along with the displacement characteristic provides a feasible method to determine the state of SMA at any point during Martensitic phase transformation. Future work aims at utilizing the thermoelectric relation of the SMA-Constantan thermocouple as a feedback variable in replacing external sensor.
Application of SMA Actuators to Spacesuit Glove Mobility
Authors: Atkinson Grant , Kirkpatrick Kenton , Hartl Darren , Valasek John
Published: July 2013

A common problem with space suit systems is overly rigid gloves that resist astronaut finger motion and gripping. In this paper, the design of a mechanism is considered that exploits the small-scale nature of shape memory alloys for actuating glove fingers to assist hand gripping. The design problem is introduced by considering the objectives, constraints, and variables relevant to a spacesuit glove actuator design. Advantages and disadvantages of shape memory alloys for this application are presented. The selection of a specific shape memory alloy composition is considered, as well as specimen dimensions and connection configuration, based on ergonomic considerations. Mechanism actuation was then simulated using finite element analysis of a simulated glove-finger-actuator assembly. The results of this paper show that the designed shape memory alloy mechanism is feasible for assisting astronaut hand gripping.
Clarifying the Carbon Nanotube Actuation Mechanism: An Experimental Approach
Authors: Geier Sebastian M. , Müller Stephan , Mahrholz Thorsten , Wierach Peter , Riemenschneider Johannes , Sinapius Michael
Published: July 2013

Experimental investigations of different architectures made of pure, as produced carbon nanotubes (CNTs) are the main focus of this presented article. Different types of experimental setups are used to analyze the free strain of the CNT-based architectures. According to their build-up different experimental setups like actuated tensile tests, in-plane and out-of-plane strain measurements are realized to investigate the actuation mechanism and possible dependencies. The first analyzed architecture can be characterized as a 2D paper of randomly oriented, entangled single walled CNTs, also called Bucky-paper. In contrast the second investigated architecture consists of highly oriented, vertically aligned multi walled CNTs grown on a substrate of glassy carbon. The results are evaluated according to findings of various other material quality tests in order to find a significant statement for their possible actuation mechanisms.
NMR Characteristics of Photomechanics and Thermomechanics of Azobenzene Polymer Networks
Authors: Worden Matt , Wang Hongbo , Paravastu Anant , Oates William S.
Published: July 2013

Azobenzene polymer networks have drawn interests in the area of adaptive materials and structures due to their novel photo-responsive material coupling. These materials undergo a complex light driven molecular conformation change of the azobenzene chromophore when the material is exposed to ultraviolet (UV) or blue-green light. This photoisomerization process is characterized by a molecular conformation change from a rod shaped molecule to a strongly kinked molecule, also known as trans-cis photoisomerization under UV light exposure. Exposure to blue-green light can lead to a trans-cis-trans photoisomerization or a relaxation from the kinked cis state back to the trans rod state. The latter process is of strong interests for adaptive structure applications because the relaxation back to the trans state can be controlled by the orientation of polarized light. When these azobenzene molecules undergo this process in a polymer network, bending and twisting deformation can be controlled by the polarization orientation of the blue-green light. To better understand the distribution of the molecular conformation changes that influences macroscopic polymer deformation, we have conducted solid state Nuclear Magnetic Resonance (ss-NMR) tests on fluorine doped azobenzene polymer networks. Here, we illustrate measurable chemical shifts due to blue light exposure near the 450 nm wavelength using a static ss-NMR probe. The results are compared to ss-NMR at different temperatures using Magic Angle Spinning (MAS) NMR to understand any potential influences of heat relative to photoisomerization.
Ceramic Siloxane Composite as a Future Elastomer Dielectric for Micro-Actuator Realization
Authors: Soulimane Sofiane , Shih Wen-Pin , Vedrenne Marc , Camon Henri
Published: July 2013

Polymer materials have been proposed to be good candidates for the development of new actuators. Due to their tunable mechanical and electrical properties, they can be used as electro-active devices. In this contribution, we focus on dielectric elastomers based actuators, and word toward establishing innovative and alternative integration/miniaturization processes inspired from microelectronics and MEMS technology. Dielectric elastomer actuators are made of an elastomer dielectric layer sandwiched between two conductive electrodes. Upon voltage application attraction forces between the electrodes generates a mechanical displacement correlated with the elastomer Young modulus and permittivity. Here, we propose to use the polydimethylesiloxane (PDMS) due to its high elasticity and its permittivity made adjustable by addition of ceramic nanoparticles. An original process for structuring PDMS layers is developed to overcome the technological challenges encountered during the integration of such materials in a micro-actuator. In this paper, we present several results of characterization that allowed us to better understand the physicochemical mechanisms involved at different technological steps for both the material alone or mixed with Titanate of Barium (TiO3Ba) nanoparticles. We also measured the permittivity and the elasticity modulus of these materials at the end of the manufacturing process thereby verifying the conservation and the enhancement of the initial properties that set our choice. These results are very promising for increasing the electrostatic pressure or to lower the actuation voltage. To make a prediction of permittivity by a mixing rule, we inspect some theories in this aim. Finally, we demonstrate that the actuation response of charged elastomer with TiO3Ba nanoparticles follows a hyperelastic behavior. This result is particularly helpful for the design of a micro-actuator in a given application.
Electromechanical Impedance Modeling for Structural Health Monitoring
Authors: Zhao Liuxian , Yu Lingyu , Gresil Mattieu , Sutton Michael , Guo Siming
Published: July 2013

Electromechanical impedance (EMI) method is an effective and powerful technique in structural health monitoring (SHM) which couples the mechanical impedance of host structure with the electrical impedance measured at the piezoelectric wafer active sensor (PWAS) transducer terminals. Due to the electromechanical coupling in piezoelectric materials, changes in structural mechanical impedance are reflected in the electrical impedance measured at the PWAS. Therefore, the structural mechanical resonances are reflected in a virtually identical spectrum of peaks and valleys in the real part of the measured EMI.

Multi-physics based finite element method (MP-FEM) has been widely used for the analysis of piezoelectric materials and structures. It uses finite elements taking both electrical and mechanical DOF’s into consideration, which allows good differentiation of complicated structural geometries and damaged areas. In this paper, MP-FEM was then used to simulate PWAS EMI for the goal of SHM. EMI of free PWAS was first simulated and compared with experimental result. Then the constrained PWAS was studied. EMI of both metallic and glass fiber composite materials were simulated. The first case is the constrained PWAS on aluminum beam with various dimensions. The second case studies the sensitivity range of the EMI approach for damage detection on aluminum beam using a set of specimens with cracks at different locations. In the third case, structural damping effects were also studied in this paper.. Our results have also shown that the imaginary part of the impedance and admittance can be used for sensor self-diagnosis.
Validation of a Strain-Based Wing Shape Prediction Algorithm for Control and Monitoring of an Uninhabited Air Vehicle
Authors: Alvarenga Jessica , Peña Francisco , Boussalis Helen
Published: July 2013

Recent improvements in technology has enabled the use of very sophisticated sensors such as embedded fiber bragg gratings (FBGs) to obtain strain measurements from a variety of structural types. Conventional strain gauges tend to be heavy and bulky. Because of their accuracy, light weight, small size and flexibility these fiber optic sensors have big potential to be used in space exploration and the aerospace industry especially for flying aircraft that have strict weight and size limitations. These strain measurements can be used to predict the deformation shape of aircraft during real-time flights. The development of such methods for monitoring and control can potentially reduce the risk of in-flight breakups, such as that of the Helios Wing.

The Structures, Propulsion, And Control Engineering (SPACE) NASA sponsored University Research Center (URC) of excellence has concentrated in the development of small, lightweight Uninhabited Air Vehicles (UAVs) that have excelled in the area of endurance. Today, the UAV project is focused on the design of a multi-mission multipurpose air system that can operate autonomously. The configuration is a twin boom, pusher, and conventional wing design. In this paper, methods developed by the National Aeronautic and Space Administration (NASA)’s Dryden Flight Research Center for real-time deformation shape prediction of lightweight unmanned flying aerospace structures for the purposes of Structural Health Monitoring (SHM) and condition assessment are investigated. SHM may allow for useful monitoring that would prevent such an event by providing wing shape information and structural monitoring to either a pilot or the flight system, allowing for evasive maneuvers before the breakup would occur. These methods also have the potential for increasing safety, allowing monitoring of structural integrity, detecting damages, and providing real-time flight control feedback. These methods are applied to the SPACE Center UAV for the purpose of assessing the effectiveness of the method and the potential for both SHM and control applications. In this paper, a computational finite element model of the SPACE Center UAV is developed and used to examine the method.
The Role of Compliant Joint and Flexibility on the Propulsive Performance of a Self Propelled Caudal Fin
Authors: Kancharala Ashok K. , Philen Michael K. , Patil Mayuresh J.
Published: July 2013

Caudal fin plays an important role in the thrust generation of fish locomotion. Recent studies on the role of body flexibility in propulsion show that fish have a remarkable ability to control or modulate the stiffness of the fin for optimized propulsive performance. Along with the fin stiffness, the stiffness of the joint connecting the caudal peduncle and the fin also plays a major role in the generation of thrust. Since thrust and efficiency are dependent on various parameters, a detailed investigation would be required to understand the combined effect of fin and joint flexibility over a wide range of parameters for optimized performance. The present study provides a parametric study on the effect of flexibility of fin and the compliant joint on propulsive performance. For this investigation, fluid structure interaction of the fin has been modeled considering unsteady slender wing theory coupled with the nonlinear Euler-Bernoulli beam theory. The compliant joint has been modeled as a torsional spring at the leading edge of the fin. A comparison of Self–propelled speed (SPS) and efficiency with parameters such as heaving and pitching amplitude, oscillation frequency, flexibility of the fin and the compliant joint is reported. The model predicts the optimized stiffnesses of the compliant joint and the fin for maximum efficiency. These optimal stiffnesses vary with the motion parameters suggesting the benefits of active stiffness modulation in bio-inspired underwater robotics.
Multi-Source Energy Harvesting Schemes With Piezoelectrics and Photovoltaics on an Avian Bio-Logger Draft
Authors: Schlichting Alexander , Shafer Michael , Garcia Ephrahim
Published: July 2013

Solar energy harvesting possesses relatively high energy and power densities when compared to other energy harvesting methods. However, solar energy harvesting applications are severely limited by diurnal cycles and weather patterns. For biological applications, such as avian bio-loggers, the subject’s activity levels and location introduce further variability into the availability of solar energy. This work focuses on the challenges associated with developing a multi-source energy harvesting solution and overall power management system for an avian bio-logger. It uses an ATmega128RFA1 microcontroller along with lithium batteries and both a solar and piezoelectric energy harvester. The power management system and microcontroller operation were tested using a solar harvester.
Modeling Approach for a Fluid Movement Induced by Magnetic Forces for Viscous Loss Reduction of MRF Brakes and Clutches
Authors: Güth Dirk , Schamoni Markus , Maas Jürgen
Published: July 2013

A challenge that is opposed to a commercial use of actuators like brakes and clutches based on magnetorheological fluids (MRF), are durable no-load losses, because a complete torque-free separation due to the permanent liquid intervention is inherently not yet possible. In this paper, the necessity of reducing these durable no-load losses will be shown by measurements performed with a MRF brake for high rotational speeds of 6000min−1. The detrimental high viscous torque motivates the introduction of a novel concept that allows a controlled movement of the MRF from an active shear gap into an inactive shear gap, enabling a complete separation of the fluid engaging surfaces. This behavior is modeled by the use of the ferrohydrodynamics and simulations are performed for different transitions between braking and idle mode. Images of high speed video capturing, showing the motion of MRF induced by a magnetic field, are presented for the validation of the modeling approach. Measurements performed with a realized proof-of-concept actuator show that the viscous induced drag torque can be reduced significantly.
Predicting the Magneto-Mechanical Behavior of MSMAs Subject to Complex Load Paths
Authors: Feigenbaum Heidi P. , Ciocanel Constantin , Waldauer Alex
Published: July 2013

The microstructure of magnetic shape memory alloys (MSMAs) is comprised of tetragonal martensite variants, each with their preferred internal magnetization orientation. In the presence of an external magnetic field, the martensite variants tend to reorient so that the preferred internal magnetization aligns with the external magnetic field. As a result, MSMAs exhibit the shape memory effect when there is a magnetic field in the vicinity of a material point. Furthermore, the tetragonal nature of the martensite variants allows for a compressive stress to cause variant reorientation. This paper studies the magneto-mechanical behavior of MSMAs under various load paths, including complex loading conditions where both the applied magnetic field and compressive stress vary simultaneously.

Typically, MSMAs have been studied experimentally and modeled mathematically with either axial compressive stress or transverse magnetic field varying and the other remaining constant. For each load case, the mathematical models are calibrated with a set of experimental data that mimics those to be predicted. Model parameters have been found to be quite different when the calibration was performed with experimental results from different load cases.

This work investigates if current models, namely the Kiefer and Lagoudasmodel or the Waldauer et al. model, are capable of predicting both of the typical loading configurations mentioned above with a single calibration. Furthermore, this work uses the Waldauer et al. model to simulate more complex loading, where an MSMA element is subject to simultaneously varying stress and field; this type of loading might occur if an actuator is being designed to displace a variable load over a controlled distance.
Equilibrium Conditions and Evolution of Needle Domain Arrays in Ferroelectric Single Crystals
Authors: Carka Dorinamaria , Landis Chad M.
Published: July 2013

Experimental imaging of ferroelectric single crystals often reveals the formation of periodic arrays of needle-shaped domains of a compatible polarization variant coexisting with a homogeneous single domain parent variant. This study examines the far field electromechanical loading conditions that favor the formation, existence and evolution of compatible and stable needle domain array patterns using a phase-field modeling approach. The infinite arrays of needles are modeled via a representative unit cell and the appropriate electrical and mechanical periodic boundary conditions. A theoretical investigation of the generalized loading conditions is carried out to determine the sets of averaged loading states that lead to stationary needle tip locations. The resulting boundary value problems are solved using a non-linear finite element method to determine the details of the needle shape as well as the field distributions around the needle tips.