bluuebunny/crossref_metadata_2025 huggingface dataset:
Mycorrhizal divergence and selection against immigrant seeds in forest and dune populations of the partially mycoheterotrophicPyrola rotundifolia
Authors: Jacquemyn Hans , Waud Michael , Brys Rein
Published: November 2018

Plant populations occupying different habitats may diverge from each other over time and gradually accumulate genetic and morphological differences, ultimately resulting in ecotype or even species formation. In plant species that critically rely on mycorrhizal fungi, differences in mycorrhizal communities can contribute to ecological isolation by reducing or even inhibiting germination of immigrant seeds. In this study, we investigated whether the mycorrhizal communities available in the soil and associating with the roots of seedlings and adult plants of the partially mycoheterotrophicPyrola rotundifoliadiffered between populations growing in sand dunes and forests. In addition, reciprocal germination experiments were performed to test whether native seeds showed higher germination than immigrant seeds. Our results showed that the mycorrhizal communities differed significantly between forest and dune populations, and that within populations seedlings and adults also associated with different mycorrhizal communities. In both forest and dune populations, mycorrhizal communities were dominated by members of the Thelephoraceae, but dune populations showed a higher incidence of members of the Inocybaceae, whereas forest populations showed a high abundance of members of the Russulaceae. Reciprocal germination experiments showed that native seeds showed a higher germination success than immigrant seeds and this effect was most pronounced in dune populations. Overall, these results demonstrate that plants ofP. rotundifoliagrowing in dune and forest habitats associate with different mycorrhizal communities and that reduced germination of non‐native seeds may contribute to reproductive isolation. We conclude that selection against immigrants may constitute an important reproductive barrier at early stages of the speciation process.
Persistence of cities: Evidence from China
Authors: Duan Fan , Unel Bulent
Published: November 2018

Using data from the Qing dynasty, we investigate the long‐run impact of early development on today's living standards in China. We use city‐level population density in 1776 as a measure of early economic prosperity, and examine how it is associated with today's development indicators such as the average night light density, GDP per capita, average years of schooling, and trade openness. We find that cities which were more prosperous during the Qing dynasty are now also brighter, richer, more educated, and more open.
Movement‐Based Influence: Resource Mobilization, Intense Interaction, and the Rise of Modernist Architecture
Authors: Guillén Mauro F. , Collins Randall
Published: November 2018

We argue that the long‐term influence of actors in fields of cultural production depends on the opportunities for resource mobilization offered by external conditions combined with intense interaction among actors. Using a unique data set of 1,143 architects active between 1890 and 1940, at a time of large‐scale socioeconomic transformations and political disruption, we find by multiple regression analysis that exposure to industrialization and political upheaval, and halo effects in an architect's network of collaborators predict greater ultimate impact, while urbanization and professional affiliations do not. Theory of social movements and theory of cultural production thus have important implications for each other.
What might Normalisation Process Theory bring to policy implementation studies? Learning lessons and uncovering questions through a case study of the profound implementation failure of a new policing policy
Authors: Mackenzie Mhairi , Bradley Lisa , Stanley Nicky , Gannon Maria , Barton Deborah , Cosgrove Katie , Conway Ellie , Feder Gene
Published: November 2018

Normalisation Process Theory (NPT), used nationally and internationally to explore implementation within health services research, is used for the first time within policing to understand profound policy implementation failure and to generate broader discussion of policy implementation theory. The policy in question (Police to Primary Care [P2PC]) was an intervention designed to notify GPs when women are assessed by police as at high risk of future domestic abuse. Designed to improve interagency communication, it took place amidst radical organisational change.

Using qualitative interviews with domestic abuse specialist and frontline officers, this paper addresses how NPT helps to explain the (non)implementation of P2PC, how such an analysis differs from other policy implementation approaches, and what this means for our understandings of policy implementation more broadly.

NPT proved useful in understanding mechanisms leading to (non)implementation of the intervention: fuzzy alignment with existing practice, faulty communication of purpose, and inattention to discretionary implementation spaces. It helped us understand why the intervention came to be invisible. Dwarfed by its organisational context, made institutionally hard to read by a lack of formal protocols, and given restricted view to police officers, it was compromised by a failure to instigate systems of organisational learning.

More broadly, NPT helped reveal practices intersecting top‐down and bottom‐up implementation theory. The paper concludes by asking how NPT and theories of street‐level bureaucracy might be better used in tandem and, particularly, how this might help explorations of policy implementation where human actors are joined by technological actors in interpreting and making policy in vivo.
Mixed Matrix Membrane Performance Prediction for Gas Separation using Modified Models
Authors: Salimi A. , Bakhtiari O. , Moghaddam M. K. , Mohammadi T.
Published: November 2018

Gas separation using membrane processes are potentially economical in industrial scale. Two parameters are used for analyzing the membrane separation performance: permeability and selectivity. There is a trade off between them for polymeric membranes that makes it impossible to increase both of them simultaneously. Molecular sieve membranes, on the other hand, exhibit high permeability and selectivity but are brittle in nature and costly. A new generation of membranes has made many hopes to use simultaneously both desired properties of polymers and molecular sieves in a structure called “mixed matrix membrane (MMM)” where a molecular sieve is incorporated within a polymer matrix. As other branches of science and engineering, having a tool to predict MMMs performance seems to be essential to save time and money for research and industrial applications. Many mathematical models were developed to predict MMMs performance based on separation performance of fillers and polymers. Maxwell model is the simplest model developed for prediction of electrical properties of composite materials but it is not perfect for all cases. Some modifications were performed on Maxwell model and some other modified models were developed for better prediction of MMMs separation performance. In this research, modified Maxwell and Bruggeman models were employed to predict gas separation performance of some MMMs in the current work and the results were acceptable for all non–ideal cases which might be occurred in MMMs structure.
Electron Beam Initiated Cross–linking in Hybrid Nylon 66 Membranes
Authors: Mohammad A. W. , Linggawati A. , Ghazali Z.
Published: November 2018

Electron beam (EB) irradiation at dose of 80 kGy in air has been used as a cross–linking initiator in hybrid nylon 66 membranes to improve the properties and performance of the membrane for separation processes. The cross–linking was characterized by gel content, swelling, scanning electron microscopy (SEM), and thermal stability. Membrane performance was investigated by pure water permeation and by rejection of raffinose and vitamin B12. The results showed that the EB irradiation successfully initiated cross–linking in hybrid nylon 66 membranes.
Fabrication of Bi1.5Y0.3Sm0.2O3–δ–Based Dual–layer Ceramic Hollow Fibre Membranes for Catalytic Reactions
Authors: Othman N. H. , Wu Z. , Li K.
Published: November 2018

In this study, a dual–layer ceramic hollow fibre membrane consisting of two functional layers, i.e. an outer oxygen separation layer (Bi1.5Y0.3Sm0.2O3–δ (BYS)– L0.8Sr0.2MnO3 (LSM)) and an inner catalytic substrate layer (BYS–NiO), has been developed using a single–step co–extrusion and co–sintering technique. The key factors in successful fabrication of such membranes and morphology control have been investigated, in which how to match the sintering behaviours of the two layers is critically important. The use of BYS, a great ionic conducting ceramic, is proved to be efficient in promoting oxygen permeation at lower operating temperatures, when compared with previous counterpart, ((ZrO2)0.90(Sc2O3)0.10(ScSZ)–LSM. This demonstrates its potentials in developing new functional dual–layer ceramic hollow fibre membranes. Moreover, the membranes of this type can be used as a highly compact membrane reactor for catalytic reactions, such as partial oxidation of methane (POM) to syngas and methane combustion, because such a reactor design combines oxygen separation (from ambient air) and methane conversion into a single unit, which significantly reduces the reactor volume due to the extremely high surface area/volume of the hollow fibre configuration.
Carbon Nanotube Incorporated Nanocomposite Membranes for CO2 Removal
Authors: Zulkifli N. I. , Goh P. S. , Wong K. C. , Lau W. J. , Ismail A. F.
Published: November 2018

Thin-film nanocomposite (TFN) membranes that consist of multi-walled carbon nanotube (MWNT) incorporated polyamide selective layer formed on polysulfone substrate were developed. The resultant TFN membranes were used for CO2 gas removal. For inclusion into these active layers, a grafting procedure for CNT was established in this study to enhance their hydrophobicity. MWNTs grafted with poly (methyl methacrylate) (PMMA) were synthesized via a micro emulsion polymerization of methyl methacrylate (MMA) in the presence of acid-modified multi-walled carbon nanotubes (c-MWNTs). Subsequently, polyamide TFN membranes containing PMMA–MWNTs were prepared via interfacial polymerization reaction between aqueous and organic phases. The resultants TFN were characterized by using FTIR and SEM. Morphology studies demonstrate that MWNTs have been successfully embedded into the active polyamide layer. The gas selectivity increased about 6.6 times compared to the thin-film composite membrane when using 0.35 w/v% amine in the aqueous phase, 0.28 w/v% trimesoyl chloride (TMC) in organic phase and 0.50g/L PMMA–MWNTs in coating layer.
Gas Permeation Properties of Asymmetric Polyimide Membranes Made by Ion–beam Irradiation
Authors: Sannomiya A. , Iwase M. , Nagaoka S. , Suzuki Y. , Iwaki M. , Kawakami H.
Published: November 2018

In this study, the gas permeance and selectivity of the asymmetric polyimide membrane with skin layer carbonized by He ions irradiation were measured using a high vacuum apparatus with a Baratron absolute pressure gauge at 76 cmHg and 35°C. Particutarly, we focused on the effects of the depth profile of the energy loss for the irradiating He ions in the skin layer on the gas permeation properties of the asymmetric membranes. Irradiation depth is gauged through the energy loss profile of the irradiating ions. The nature of the carbonised layer was investigated using AFM and ATR–FTIR. We demonstrated that the PO2 of the He+–irradiated membranes increased with the skin layer thickness and that the depth of the irradiating ions in the skin layer had a significant influence on the gas permeability and selectivity of the asymmetric membrane.
Effect of Polymer Concentration on the Morphology and Mechanical Properties of Asymmetric Polysulfone (PSf) Membrane
Authors: Ismail N. M. , Jakariah N. R. , Bolong N. , Anissuzaman S. M. , Nordin N. A. H. M. , Razali A. R.
Published: November 2018

Polymer concentration had been identified as one of the important parameters tailoring the membrane properties. In this work, the effects of polymer concentration on the morphological and mechanical properties of membrane were investigated at three different polymer concentrations, i.e., 20, 25 and 30 wt%. The viscosity of dope solutions were determined to estimate the optimum polymer concentration.  The morphological properties of the fabricated membrane were determined using SEM whereas the mechanical properties of the membrane were investigated using tensile tester. Results show that an increase in the polymer concentration could lead to the improvement of the morphological and mechanical properties of the membrane. The tensile strength of the membrane determined for PSf-20, PSf-25 and PSf-30 are 5.73, 6.59 and 7.03 MPa, respectively whereas the elongation at break measured for the membranes are 46.99%, 69.18% and 36.27%, respectively. As shown in this work, the polymer concentration played a significant role to alter on membrane morphology and mechanical strength.
Preparation and Characterization of Blending Sulfonated Poly(ether ether ketone) with Charged Surface Modifying Macromolecules
Authors: Mohd–Norddin M. N. A. , Ismail A. F. , Matsuura T. , Rana D.
Published: November 2018

Charged surface modifying macromolecule (cSMM) end capped with sulfonic group was prepared and blended into sulfonated poly(ether ether ketone) (SPEEK). The modified membrane was characterized for polymer electrolyte membrane application; i.e. a SPEEK/cSMM blend membrane was compared to a SPEEK membrane and a Nafion 112 membrane for the thermal and mechanical stability, hydrophilicity and water uptake. Thermal and mechanical stability of the blend membrane were slightly reduced from that of the SPEEK membrane but still higher than that of the Nafion 112 membrane. The cSMM which was end–capped with sulfonic group has increased the total –SO3H group in the blend membrane. As a result, the blend membrane showed an increase in hydrophilicity and water uptake as compared to the pristine membrane. The addition of cSMM with an additional –SO3– charge has enabled the water uptake to be increased which is crucial to enhance the proton conductivity that of SPEEK. Moreover, the extra –SO3– can facilitate the transfer of proton better. This study found that cSMM is a good candidate as an additive for SPEEK in improving its function as polymer electrolyte membrane.
Porous Ceramics Membrane Preparation from Ternary Mixtures of Ranong Kaolin, Calcium Carbonate and Silica
Authors: Darunee B. , Nucharee C. , Tripob B.
Published: November 2018

Porous ceramics membranes were prepared from ternary mixtures of Ranong kaolin, calcium carbonate and silica using slip casting technique. Totally 10 different composition mixtures were selected from the ternary diagram of CaCO3 : SiO2 : Clay with weight fraction of 0–0.19 : 0.28–0.47 : 0.52–0.71, respectively. The ceramic paste was first fired at 800°C and then sintered at temperatures of 1200, 1250 and 1300°C. The results show that firing temperature above 1200°C is probably too high to prepare the porous ceramics of the studied compositions. The porosity less than 26% is obtained from the samples sintered at 1250–1300°C. The highest porosities of more than 40% are observed from the samples sintered at 1200°C with the weight fraction of clay, calcium carbonate and silica between 0.524–0.562, 0.076–0.152, and 0.310–0.394, respectively. In this range of compositions, the linear shrinkage and water absorption is about 3% and 22%, respectively, while the bending strength is between 28–30 MPa. The pure water flux of samples prepared from mixture formula 9 sintered at 1200°C ranges between 52.4 and 368.8 L/m2.h at the operating pressures 30–120 kPa, indicating that the mixture compositions nearby the formula 9 are the best for porous ceramic production using Ranong kaolin.
Numerical Study on the Effects of Linear Protrusion on Flow-Induced Carriage Excitation Force in Hard Disk Drives
Authors: Koganezawa Shinji , Tsuda Shotaro , Tani Hiroshi , Lu Renguo , Tagawa Norio
Published: November 2018

The positioning accuracy of magnetic heads need to be improved to increase the recording capacity of hard disk drives. In our previous study, the experimental results confirmed that the head positioning error could be decreased by attaching linear protrusions on the leading edge of the carriage arms. However, the mechanism underlying the phenomenon has not been elucidated. In the current research, we evaluated the effect of leading-edge protrusions on the flow-induced carriage excitation force using the finite element (FE) method analysis and the Hilbert-Huang transform (HHT). We prepared two carriage-arm FE models, with and without linear protrusions, on the leading edges of the arm, and performed the FE analyses. Subsequently, we conducted a frequency analysis by applying the HHT to the simulated torque-disturbance time series of each FE model and the results were later compared. Our results show that the leading-edge protrusions were found to decrease the mean velocity between the arm and the disk, thereby decreasing the vorticity fluctuation in the arm hole, and to decrease the fluctuations in pressure on the outer sidewall of the carriage arm around the coil support.
A Precise Position Measurement System of Roll-to-Roll Printing Using Burst Alignment Patterns
Authors: Kim Taehyeong , Oh Dongho , Kim Youngjin , Kim Jihyeon , Lee Byeongcheol
Published: November 2018

Printed electronics is a next-generation process technology that is suitable for high speed and high volume production and can make electronic devices and circuits on flexible materials. To commercialize printed electronics, it is necessary to improve the alignment precision of printing. In order to improve the alignment precision of the roll-to-roll process, accurate measurement of the web position is required. Therefore, in the previous research of this paper, we proposed a measurement system of the moving direction and the lateral movement using an encoder. However, in the previous study, the direction of error control had to be set according to the measurement position of the encoder, and the measurement range was so narrow. In this paper, we propose a measurement system that can detect the direction of error and increase the effective measurement range using the burst alignment pattern that generates the burst signal. Applying it to roll-to-roll printing position measurement systems, measurements can be performed with greatly improved efficiency and measurement range.
Printing Pressure Uniformization Through Adaptive Feedforward Control in Roll-to-Roll Printing Process
Authors: Kim Jihyeon , Oh Dongho , Kim Youngjin , Kim Taehyeong , Lee Byeongcheol
Published: November 2018

Printed electronics is a technology for making electronic devices using functional ink and flexible material film. The roll-to-roll printed electronic process is a next-generation process that is environmentally friendly and mass-productive at low cost. However, if the printing pressure between two rolls cannot be made uniform in the roll-to-roll process, it is difficult to commercialize the printed electronics due to the degradation of the printing quality. Previous study has proposed a method to select the initial condition that minimizes the printing pressure change using shape information of the roll and minimized printing pressure is verified by using the load cell signal. However, repetitive pressure errors that occur as the roll rotates require printing pressure uniformization control. In this paper, the printing pressure is predicted by using the shape information of the roll, and adaptive feedforward control is performed based on the predicted result to uniformize the printing pressure. Then, the experimental results are verified using a load cell signal.
TOF-SIMS Analysis of Accumulated PFPE Lubricant Smear Following Laser Heating
Authors: Tani Hiroshi , Shibahara Yuta , Lu Renguo , Koganezawa Shinji , Tagawa Norio
Published: November 2018

The structural and molecular weight changes to lubricant picked up following laser heating in heat-assisted magnetic recording (HAMR) were analyzed using time-of-flight secondary ion mass spectrometry (TOF-SIMS). The intensity of the ion mass fragments depended on the decomposition pathways and changed drastically, as did the average molecular weight of the picked-up lubricant as heating temperature increased. The fragment series formed by the dissociation of end groups with low molecular weights (CH3O+) showed a high intensity at temperatures under 300 °C, whereas at temperatures over 400 °C, the fragments series formed by the dissociation of the end-group component (C5H9O4F2+) increased. Overall, the results presented herein suggest that the chemical and thermal stability of the hydrocarbon terminal ends of lubricants should be improved in order to decrease depletion of the lubricant film and lubricant pickup by laser heating in HAMR.
Pose Calibration Method of 6-D.O.F. Cable Driven Parallel Robot Using Hybrid Recurrent Neural Network
Authors: Choi Sung-Hyun , Park Kyoung-Su , Heo Jun-Mu , Ha Hue
Published: November 2018

Cable driven parallel robots (CDPRs) have been widely used in precision Industries. However, an error occurs in repetitive motion of the CDPR because of the elongation and recovery of cable. Also, it is difficult to apply the numerical cable model because of its complexity. In this paper, we use the frequency based H-RNN method for accurate kinematics. H-RNN predicted more accurately compared with LSTM and RNN algorithms.
Study of Lubricant Depletion Induced by Pulsed-Laser Irradiation Heating in Heat-Assisted Magnetic Recording
Authors: Tagawa Norio , Tani Hiroshi , Uesaraie Yuki , Koganezawa Shinji , Lu Renguo
Published: November 2018

In this study, we experimentally investigated the lubricant depletion caused by pulsed-laser irradiation heating and discussed the fundamental characteristics, comparing it with the results obtained by continuous laser heating. As a result, it was found that the decrease in the lubricant depletion due to pulsed-laser heating was smaller than that to continuous laser heating and depended on an increase in the duty ratio as it increased. In addition, the lubricant depletion depends on the full width at half maximum (FWHM) of the temperature distribution due to pulsed-laser irradiation heating and increased as the FWHM increased. Therefore, it is also suggested that the lubricant depletion issue will not be so critical in actual HAMR systems because the FWHM would be very small.
An Effect of Acceleration on Passively-Changed Arm-Velocity Perception
Authors: Yasui Takaaki , Akatsuka Fumihiro , Nomura Yoshihiko , Sugiura Tokuhiro
Published: November 2018

In recent years, the methods of motor learning using haptic devices that can give motion-related stimuli to learners have been studied. In order to design control systems of the haptic devices that can give learners stimuli so that they can perceive them with proprioception, we need to understand the characteristics of human’s position and velocity sensations. Then, in this study, we examined velocity JNDs (Just Noticeable Differences), in order to understand human velocity-change perception. We, in particular, focused on an effect of acceleration during velocity-change to human velocity-change perception. In the experiment, we enforced subjects to accelerate their hands with a constant acceleration of 1, 8, 16, 32 deg/s2 from before-acceleration velocity of 10 deg/s. Subjects answered whether they perceived velocity-change or not, and we measured velocity JNDs. As a result, it was found that, while the accelerations increased by 32 times, the velocity JNDs decreased by only about 1/2, i.e., from 8.1 to 4.2 deg/s. From this result, it was concluded that the magnitude of acceleration is not a determinative factor for velocity-change perception but a supplementary one.
Optimization of an Interferometric Pressure Sensor for Intraocular Pressure Measurements
Authors: Phan Alex , Truong Phuong , Trumpp Julian , Talke Frank E.
Published: November 2018

This paper studies the effect of thin film thickness on visibility readout from an interferometric pressure sensor. Interference fringes between a silicon nitride diaphragm and a glass substrate are formed as a function of pressure and can be captured using a camera. Image processing software was used to analyze and correlate the fringe pattern to pressure. Visibility of the interference fringes is optimized by depositing a thin silicon nitride layer on the glass substrate of the sensor using plasma enhanced chemical vapor deposition (PECVD). Optimal visibility was obtained with a coating thickness of 79 nm. Visibility was increased by 150% in comparison to no coating.
Influence of Paper Lint on Friction and Wear of Rubber Rollers
Authors: Tsukiyama Yosuke , Nitta Isami
Published: November 2018

This paper deals with the influence of surface contamination on the frictional mechanisms of rubber rollers. The contamination which adhered on the rollers after feeding many sheets of papers is one of the predominant causes of paper jams. However, the mechanism has not been understood. The purpose of this paper is to clarify the relationships between the friction force and the real contact area of papers and contaminated rubber rollers. Carrying out paper feeding tests by using a commercial multifunction peripheral, we tested different types of papers produced by different manufacturers. The tests have been done with combinations of different manufacturer’s papers and different kinds of roller materials. Observations of the real contact area clarified that the roller surfaces covered with paper powders or lint reduces the friction coefficient.
Understanding of Final-State Control Technique in Motion Control Problems From the Viewpoint of Model Predictive Control Theory
Authors: Hara Susumu , Yokoo Ryuya , Miyata Kikuko , Tsubakino Daisuke
Published: November 2018

In many motion control problems of mechatronic equipment, the control performance of the final-state of the control period is strictly important for positioning or settling issues. Totani and Nishimura proposed a final-state control (FSC) method using compensation input for such a purpose in 1994. The FSC technique has been improved and applied to various kinds of actual mechanical motion control problems. The FSC technique looks similar to the Mode Predictive Control (MPC). However, the difference of FSC and MPC has not been fully addressed yet. This paper shows the understanding of FSC technique from the viewpoint of the MPC theory. An updating-type FSC (UFSC) proposed by a part of the authors is introduced. Then, this paper shows analytically that the control input in UFSC can be obtained by the theory of MPC under some conditions. This analysis makes clear the meaning of “updating” in the FSC technique for actual mechanical motion control applications.
Study on Fabrication of Porous Nanosheets by Roll Nanoimprinting Method
Authors: Kamimura Go , Zhang Sheng , Tsuchiya Kazuyoshi , Hashimoto Hiromu , Sunami Yuta
Published: November 2018

In this research, the fabrication of polymer ultra-thin films (nanosheets) using a micro gravure printing method was studied. The effects of the conveying speed of the plastic film substrate, the concentration of solution and rotating speed of the micro gravure roll on the film thickness of the nanosheets were investigated through experimental approach. The polyethylene terephthalate film was placed as a substrate by a roller. After applying the tension load directly to the film, polyvinyl alcohol was coated on the PET film in order to release the nanosheets from the PET film by the sacrificial layer method. After that, polylactic acid (PLLA) was coated. Thickness of nanosheets was measured by using a stylus type surface profile. In addition, in the micro / nano field, nanoimprint technology is capable of pressing a mold having an irregular pattern of several tens nanometer level onto a resin. In order to further enhance the functionality of the nanosheets, the press method and the roll nanoimprinting method can be used to produce a fine structure, and press the nanosheets without heating. As a result, since the shape of the mold could be transferred, it is possible to fabricate the nanosheets with the microstructures by the roll nanoimprinting method. In the case of fabricating porous nanosheets by the roll nanoimprinting method, the microstructures were smaller than a hot press method. And the pressed microstructures on the nanosheets without heating were smaller than the microstructures with heating.
Design Development of Rotational Energy Harvesting Vibration Absorber (R-EHTVA)
Authors: Infante Francesco , Kaal William , Perfetto Sara , Herold Sven
Published: November 2018

This paper proposes a novel idea of a combined piezoelectric energy harvesting and torsional vibration absorber for rotating system. In particular, among possible alternative solutions for durable power sources useable in mechanical components, vibration represents a suitable method for the amount of power required to feed a wireless sensor network. For this purpose energy harvesting from structural vibration has received much attention in the past few years. Suitable vibration can be found in numerous mechanical environments including automotive moving structures, household applications, but also buildings and bridges. Similarly, a dynamic vibration absorber (DVA) is one of the most used devices to mitigate the vibration structures. This device is used to transfer the primary structural vibration to the auxiliary system. Thus, vibration energy is effectively localized in the secondary less sensitive structure and it can be harvested. This paper describes the design process of an energy harvesting tuned vibration absorber for rotating system using piezoelectricity components. Instead of being dissipated as heat, the energy of vibration is converted into electricity. The device proposed is designed to mitigate torsional vibrations as a rotational vibration absorber and to harvest energy as a power source for immediate use. The initial rotational multi degree of freedom system is initially reduced in equivalent single degree of freedom (SDOF) systems. An optimization method is used for evaluating the optimal mechanical parameters of the initial absorber for the SDOF systems defined. The design is modified for the integration of the active patches without detuning the absorber. In order to estimate the real power generated, a complex storage circuit is implemented. A fixed voltage is obtained as output. Through the introduction of a big capacitor, the energy stored is measured at different frequencies. Finally, the simultaneously achievement of the vibration reduction function and the energy harvesting function is evaluated.
Influence of the Manufacturing Process on Hot Extruded Shape Memory Alloy Metal Matrix Composites
Authors: Dahnke C. , Tekkaya A. E.
Published: November 2018

Continuous composite extrusion offers the possibility for manufacturing shape memory alloy metal matrix composites (SMA-MMC) with an actuator function. Due to an eccentric position of the SMA wires as well as the transformation stress caused by the suppressed shape memory effect, a bending moment can be generated during thermal activation. In this paper it is examined how the amount of necessary prestrain as well as the activation temperature influences the generated curvature of the specimens. The investigated actuator concept requires a sufficient bonding between matrix material and SMA wire to transfer the occurring stresses. For this reason, it is furthermore investigated how the process steps of stretching and subsequent thermal activation affect the quality of the bonding zone. Conventional NiTi wires (SM495) with a diameter of 1.5 mm are embedded in an aluminum AA6060 matrix for experimental investigation.
Towards a Design Framework for Multifunctional Shape Memory Polymer Based Product in the Era of 4D Printing
Authors: Jian Bingcong , Demoly Fédéric , Zhang Yicha , Gomes Samuel
Published: November 2018

Shape-memory polymers (SMPs) as stimuli-responsive shape-changing materials gained significant interest in recent years. Their developments have challenged the conventional understanding of the polymer effect and have further enhanced and broadened the applications of the smart materials. Nowadays, 4D printing is seen as an emerging technology that combines smart materials and additive manufacturing, which can be used to design active mechanical structures. It provides tremendous potential for engineering applications which is capable of producing complex, stimuli-responsive 3D structures. While many “ad hoc” designs of 4D printed solutions have been progressively developed for a specific process, the general approach of additive manufacturing that integrates smart materials in real time across an entire product development process is not pervasive in the industry. To solve this issue, the authors propose a general 4D printing oriented framework for the design of multi-functional SMPs architectures. This framework is not intended to be an exhaustive and specific instruction but is instead a means to motivate these designers to seek the process of applying these unique functional materials to their own designs and applications. It will be useful and give more insight into the design process of the SMP device.
Induced Strain Actuation for Solid-State Ornithopters: An Aeroelastic Study
Authors: Hauris Francis , Bilgen Onur
Published: November 2018

This paper investigates the dynamic aeroelastic behavior of strain actuated flapping wings with various geometries and boundary conditions. A fluid-structure interaction model of a plate-like flapping wing is developed. Assuming a chord Reynolds number of 100,000, the wing is harmonically actuated while varying parameters such as aspect ratio and wing root clamped percentage. Characteristic metrics for the dynamic motion, natural frequency, lift and drag are developed. These results are compared with purely structural behavior to understand the aeroelastic effects.
Manufacture of Lenses and Diffraction Gratings Using DLP As an Additive Manufacturing Technology
Authors: Vallejo Melgarejo Laura Daniela , García Jose , Reifenberger Ronald G. , Newell Brittany
Published: November 2018

This document condenses the results obtained when 3D printing lenses and their potential use as diffraction gratings using Digital Light Processing (DLP), as an additive manufacturing technique. This project investigated the feasibility of using DLP additive manufacturing for producing custom designed lenses and gratings. DLP was identified as the preferred manufacturing technology for gratings fabrication. Diffraction gratings take advantage of the anisotropy, inherent in additive manufacturing processes, to produce a collated pattern of multiple fringes on a substrate with completely smooth surfaces. The gratings are transmissive and were manufactured with slit separations of 10, 25 and 50 μm. More than 50 samples were printed at various build angles and mechanically treated for maximum optical transparency. The variables of the irradiance equation were obtained from photographs taken with an optical microscope. These values were used to estimate theoretical irradiance patterns of a diffraction grating and compared against the experimental 3-D printed grating. The resulting patterns were found to be remarkably similar in amplitude and distance between peaks when compared to theoretical values.
On the Development of Tensorial Deformation-Resistivity Constitutive Relations in Conductive Nanofiller-Modified Composites
Authors: Koo G. M. , Tallman T. N.
Published: November 2018

Polymers modified with conductive nanofillers have recently received considerable attention from the research community because of their deformation-dependent electrical resistivity. Known as piezoresistivity, this self-sensing capacity of nanocomposites has much potential for structural health monitoring (SHM). However, making effective use of the piezoresistive effect for SHM necessitates having a good understanding of the deformation-resistivity change relationship in these materials. While much insightful work has been done to model and predict the piezoresistive effect, many existing models suffer from important limitations such as being limited to microscales, over-predicting piezoresistive responses, and not considering complex deformations. We herein address these limitations by developing tensor-based piezoresistivity constitutive relations. The supposition of this approach is that resistivity changes due to small deformations can be treated as isotropic and be completely described by only two piezoresistive constants — one associated with volumetric strains and a second associated with shear strains. These piezoresistive constants can easily be discerned from simple experiments not unlike the process of determining elastic constants. We demonstrate the potential of this approach by deriving these piezoresistive constants for an experimentally-validated analytical model in the existing literature. This work can enable much more accurate and easily-obtained piezoresistive relations thereby greatly facilitating the potential of resistivity change-based SHM.
On the Potential of Using the Small Punch Test for the Characterization of SMA Behavior Under Multi-Axial Loading Conditions
Authors: Kiefer Björn , Hein Jarno , Abendroth Martin , Biermann Horst , Henkel Sebastian , Niendorf Thomas , Krooß Philipp , Chemisky Yves
Published: November 2018

This work presents a first investigation of the small punch test (SPT) as a possible method to identify material parameters for shape memory alloy (SMA) behavior. In comparison to more common tests, the SPT has advantages in setup simplicity, small sample size, uncomplicated shape, and the possibility of specimen clamping, while offering controlled multi axial loading. Different loading scenarios are described and executed. The parameters of an established SMA model are subsequently (partially) calibrated from the measured SPT force-deflection curves. For some loading regimes, the effective response curves suggest the occurrence of damage events. To investigate the underlying microscale failure mechanisms, a first SEM study was conducted. These first results underline that the SPT is a promising efficient and inexpensive characterization method to support SMA constitutive model development under multiaxial loading — including aspects of damage, fracture and fatigue.
Fabrication Considerations for Bridged Microfluidic Cell Cultures
Authors: Wynne Rosalind , Ahmed Sabrina
Published: November 2018

A novel bridged-microfluidic for cell-based assays was developed by combining a microstructured optical fiber (MOF) with a microfluidic network with the purpose of continuously monitoring the state of hepatocellular carcinoma (HepG2) cells. In this configuration a solid core MOF with channels in the cladding serves as a bridge for cell transport as well as an evanescent wave-based monitoring system to detect cells labeled with fluorescent nanomaterials. The device was fabricated by positioning an MOF to bridge two polydimethylsiloxane (PDMS) microfluidic networks. Alignment strategies and pressurization considerations to produce this system are presented. Pump systems that support fluid transport through the MOF demonstrated the tendency of flow rate fluctuations even for constant microfluidic pump rates. Spectroscopic measurements confirm the delivery and motion of cells between the two neighboring microfluidic chips. The linewidth of the spectra demonstrated oscillations that were consistent with pressure broadening caused by hydrodynamic fluctuations. Fluctuations in the microfluidic flow ranging from 0.005 to 0.016 Hz were observed. These results are consistent with theoretical principles and provide important information regarding syringe pump artifacts, i.e. fluctuations, observed during spectroscopic measurements in MOF/microfluidic systems.
A New Rheological Model of Magnetorheological Fluids for CFD: Comparison and Validation
Authors: Kemerli Muaz , Engin Tahsin , Parlak Zekeriya
Published: November 2018

Magnetorheological fluid is a special smart fluid which can show different rheological properties under different magnetic flux densities due to its magnetically sensitive structure. This makes the fluid able to be manipulated and semi-actively controlled for various applications such as dampers, clutches and brakes. To provide an effective damping it is necessary to create an appropriate control algorithm. In order to design a structure with magnetorheological fluid and to get an idea for a control approach, the physics of the fluid motion has to be modelled. Computational Fluid Dynamics is an effective tool to model any fluid behaviour or any fluid involved structure. For magnetorheological devices, despite number of numerical models available in the literature, a befitting model is not yet presented. In this study a mapped rheological model is proposed and used in a magnetorheological damper simulation. The results are compared with other models and experimental data. It is shown that the new mapped model is effective and better than old approaches. It also showed a good agreement with the experimental data.
Distributed Strain Sensing Using Carbon Nanotube Thin Films and Electrical Time-Domain Reflectometry
Authors: Lee Bo Mi , Loh Kenneth J. , Lanza di Scalea Francesco
Published: November 2018

Nondestructive inspection (NDI) is an effective technique to inspect, test, or evaluate the integrity of materials, components, and structures without interrupting the serviceability of a system. Despite recent advances in NDI techniques, most of them are either limited to sensing structural response at their instrumented locations or require multiple sensors and measurements to localize damage. In this study, a new NDI system that could achieve distributed sensing using a single measurement was investigated. Here, piezoresistive carbon nanotube (CNT)-polymer thin film sensors connected in a transmission line setup were interrogated using electrical time-domain reflectometry (ETDR). In ETDR, an electromagnetic signal is sent from one end of the transmission line. When the signal encounters the sensor, it can partially reflect and be captured at the same point. The characteristics of the reflected signal depend on the sensor’s impedance, which is correlated to structural response, deformation, or damage. The advantage of this is that distributed sensing along the entire transmission line can be achieved using a single measurement point. To validate this concept, CNT-polymer thin films that were integrated with a transmission line are subjected to uniaxial tensile strains applied using a load frame. The ETDR signals were analyzed to assess the system’s sensing performance.
Experimental Study of Multifunctional NCM-Si Batteries With Self-Actuation
Authors: Ma Jun , Gonzalez Cody , Rahn Christopher , Frecker Mary , Wang Donghai
Published: November 2018

Among anode materials for lithium ion batteries, silicon (Si) in known for high theoretical capacity and low cost. Si exhibits over 300% volume change during cycling, potentially providing large displacement. In this paper, we present the design, fabrication and testing of a multifunctional NCM-Si battery that not only stores energy, but also utilizes the volume change of Si for actuation. The battery is transparent, thus allowing the visualization of the actuation process during cycling. This paper shows Si anode design that stores energy and actuates through volume change associated with lithium insertion. Experimental results from a transparent battery show that a Cu current collector single-side coated with Si nanoparticles can store 10.634 mWh (charge)/2.074mWh (discharge) energy and bend laterally with over 40% beam length displacement. The unloaded anode is found to remain circular shape during cycling. Using a unimorph cantilever model, the Si coating layer actuation strain is estimated to be 30% at 100% SOC.
Capturing Age-Dependent Properties of Human Skin Using Magnetorheological Elastomers
Authors: Weaver Kyle , Koo Jeong-Hoi , Yang Tae-Heon , Kim Young-Min
Published: November 2018

Artificial and synthetic skins are widely used in the medical field; used in applications ranging from skin grafts to suture training pads. There is a growing need for artificial skins with tunable properties. However, current artificial skins do not take into account the variability of mechanical properties between individual humans as well as the age-dependent properties of human skin. Furthermore, there has been little development in artificial skins based on these properties. Thus, the primary purpose of this research is to develop variable stiffness artificial skin samples using magnetorheological elastomers (MREs) whose properties that can be controlled using external magnetic fields. In this study, multiple MRE skin samples were fabricated with varying filler particle volume contents. Using a precision dynamic mechanical analyzer, a series of indenting experiments were performed on the samples to characterize their mechanical properties. The samples were tested using a spherical indenter that indented a total depth of 1 mm with a speed of 0.01 mm/s and unloaded at the same rate. The results show that the modulus or stiffness increases significantly as the iron percent (w/w) in the sample increases. Additionally, the stiffness of the sample increases proportional to the intensity of the applied external magnetic field. To assess the MRE samples’ variability of properties, the testing results were compared with in vivo human skin testing data. The results show the MRE samples are feasible to represent the age-dependent stiffness demonstrated in in vivo human skin testing. The MRE materials studied will be further studied as a variable-stiffness skin model in medical devices, such as radial pulse simulators.