bluuebunny/crossref_metadata_2025 huggingface dataset:
Characterization of Dissolved Organic Matter in Landfill Leachate during Two–Stage Membrane Bioreactor Treatment
Authors: Sanguanpak S. , Chiemchaisri C. , Chiemchaisri W. , Yamamoto K.
Published: November 2018

Landfill leachate is a complex wastewater containing high concentration of dissolved organic matter (DOM). In this study, DOM in raw leachate and treated water from pilot–scale two–stage membrane bioreactor (MBR) installed at solid waste disposal site were investigated by using fractionation method, fluorescence excitation–emission matrix spectroscopy (FEEM) and fourier transform infrared (FTIR). The fractionation results showed hydrophilic (Hyl) compound was the most abundant fraction in DOM of raw leachate, whereas the dominant fraction of DOM in mixed liquor inside MBR and its effluent was fulvic acid (FA). The fluorescent peaks of protein-like, humic and fulvic–like substances were detected in influent DOM, while the fluorescence peaks of MBR and effluent DOM were humic and fulvic-like substances. From the FTIR results, absorption bands that could be related to humic acid (HA) and FA were found in both MBR and effluent DOM. The characterization of DOM indicated that the most of Hyl and protein–like substances could be significantly removed by microbial process in MBR. Furthermore, a part of humic substance (HA and FA) could be eliminated by microbial and filtration processes.
Modeling and Performance Characteristics of Nanofiltration by DSPM and ARX Model
Authors: Deepak D. , Arthanareeswaran G.
Published: November 2018

The DSPM (Donnan Steric Pore Model) is integrated with osmotic pressure to develop nanofiltration modeling. The new model establishes the relation between the pressure across the membrane to the concentrations of permeate and retentate at a particular solute concentration in the feed. The model is successfully tested against the experimental data. We also developed the nanofiltration modeling with ARX (Auto Regressive Exogeneous), a type of black box model. The data for modeling is obtained by simulation of the first principle model. With the help of identification toolbox, an ARX model is developed considering pressure across the membrane as input variable (manipulated variable) and percentage rejection as output variable (control variable). The model is validated against a data subset used for estimation of model. However, the models are sustained only at low feed concentrations. The model output data are compared to the actual output data and calculate the mean square errors (MSE). The obtained residuals are well satisfactory in the range of 0.99. Hence, the derived modeling sustains for nanofiltration and its control operations.
Elimination of an Endocrine Disruptive Chemical by PSf/TiO2 hybrid Membranes via Membrane Rejection and Photocatalytic Oxidation
Authors: Babu V. S. , Jyothi M. S. , P. D’Souza Laveena , Shwetharani R. , Padaki Mahesh , Geetha Balakrishna R.
Published: November 2018

This study reports removal of oxybenzone from TiO2 nanoparticles and those incorporated mixed matrix membrane. Polysulfone and TiO2 nanoparticles mixed matrix membrane were prepared by Diffusion Induced Phase Separation (DIPS) method. The TiO2 nanoparticles and membranes were characterized by XRD, SEM, TEM, Raman spectroscopy and FESEM techniques; analysis depicts 100% anatase with spherical crystallite size averaging around 17 nm. The mixed matrix membranes were used for bifunctional application, physical separation and organic degradation. The membranes were subjected to pure water flux and contact angle measurements, the influence of TiO2 were to increase the hydrophilicity of the membrane, the performance of the membrane in physical separation showed prominent results by removing oxybenzone up to 95% where as in organic degradation membrane showed 80% of degradation. The efficiency of the membrane in degradation was more prominent as compared to bare TiO2 nanoparticles. The TiO2 nanoparticles show around 70% of degradation, whereas, the bifunctionality of the membranes showed more prominence in removal of complete oxybenzone.
Modified Boundary Condition for Membrane Wall Concentration Prediction in Narrow Membrane Channel
Authors: Ahmad A. L. , Lau K. K. , Abu Bakar M. Z. , Abd. Shukor S. R.
Published: November 2018

The efforts of CFD simulation study to reveal the membrane wall concentration in the membrane channel which consider hydrodynamics and permeation properties are found to be inadequate. Hence, the ultimate objective of this paper is focusing on the employment of modified boundary condition to model the membrane interface in the membrane channel. Permeation properties such as permeation flux and concentration have been integrated in this modified boundary condition. Commercial CFD simulation package has been utilized to predict the membrane wall concentration for different transmembrane pressure and feed Reynolds number in the membrane channel. The simulated results were validated and compared with the published data from literature, showing a satisfactory agreement. This study has proven the increment in feed Reynolds number can enhance the mass transfer rate and suppress the formation membrane wall concentration. The utilization of modified boundary condition has promoted the accuracy and capability of commercial CFD simulation package to model and predict the hydrodynamics and permeation phenomenon in the membrane channel.
Zeolite Incorporated Polycaprolactone/Zeolite Nanocomposite Membranes for Silver Removal
Authors: Sultana N. , Rusli M. S. I. , Hassan M. I.
Published: November 2018

The presence of heavy metals in drinking water leads to several health problems. Nano and micro fiber membranes can be used to overcome this through nano or microfiltration process. In this study, polycaprolactone (PCL)/zeolite electrospun composite membranes were fabricated and characterized. PCL is one of the synthetic polymers used in biomedical applications. It has several advantages, including biocompatibility, biodegradability and mechanical flexibility. On the other hand, zeolites are microporous, aluminosilicate minerals commonly used as commercial adsorbents. Electrospinning is a promising technique to produce membranes by applying high voltage electricity. In this research, an electrospinning technique was used to fabricate the electrospun membrane based on PCL and zeolite. In order to produce electrospun membrane, 15% (w/v) of PCL polymer solution was dissolved in acetone and 20% (w/v) zeolite nanoparticles were incorporated into the PCL polymer solution. The diameter range of fiber was 2-6 µm. Zeolite nanoparticles were distributed homogenously into the fibers. EDX spectrum confirmed the presence of zeolite throughout the membrane. From the performance testing, it was revealed that the membrane can be potentially used as microfiltration to entrap silver contaminants in drinking water. Apart of that, the membranes are prepared with biocompatible, non-toxic materials which can be eco-friendly.
Emulsion Liquid Membrane Extraction of Silver from Photographic Waste using Tetramethylthiuram Disulfide (TMTDS) as a Mobile Carrier
Authors: Othman Norasikin , Kit Hie Chan , Tung Chiong , Mat Hanapi , Goto Masahiro
Published: November 2018

The recovery of precious metals such as silver from photographic wastes is required in order to save raw materials and to protect the environment from dispersed compound, especially heavy metals. For that matter, several technologies have been used such as precipitation, electrolytic, and ion exchange processes which offer some advantages as well as drawbacks over others. Recently, emulsion liquid membrane extraction has been recognized to be a potential process for industrial wastes treatment and recovery of heavy metals. This process has the ability to selectively separate and rapidly concentrate metals through its very thin layer liquid membrane which has a large interfacial area. An attempt was made to recover silver from liquid photographic wastes using tetramethylthiuram disulfide as a mobile carrier. The important variables affecting the emulsion liquid membrane (ELM) process including residence time, surfactant concentration, carrier concentration, level of agitation and phase ratio between emulsion and feed phase were investigated. The results showed that tetramethylthiuram disulfide is selective towards silver (>80%) compared to other metals in the photographic waste. The highest silver extraction is obtained using 0.05 M tetramethylthiuram disulfide, 3% (w/v) Span 80, 300 rpm stirring speed, 1.0 M thiourea in 0.1 M HCl stripping agent, 1:3 of treat ratio, and toluene as the diluent.
Preparation and Characterization of High Methanol Resistance Sulfonated Poly(ether ether ketone) Membrane for DMFC Application
Authors: Jaafar J. , Ismail A. F.
Published: November 2018

High methanol resistance sulfonated poly(ether ether ketone) (SPEEK) membranes have been prepared and characterized as a potential proton exchange membrane for direct methanol fuel cell. The sulfonation process was conducted at room temperature to produce SPEEK with 60% degree of sulfonation (DS). The produced membranes were then characterized by evaluating the swelling behavior in terms of water uptake, swelling ratios and methanol sorption as a function of temperature and reaction time. Interestingly, it was observed that the methanol uptake value of SPEEK membrane was lower as compared to the water uptake value as much as 80%. This characteristic showed that SPEEK membrane possesses good resistance towards methanol which is a crucial property requires for direct methanol fuel cell (DMFC) application.
Cold Sterilization of Coconut Water Using Membrane Filtration: Effect of Membrane Property and Operating Condition
Authors: Laorko A. , Li Z. , Youravong W. , Tongjitpakdee S. , Chantachum S.
Published: November 2018

Coconut water has been considered as a nutritional, refreshing and highly isotonic beverage with delicate aroma and flavor. In food sterilization technique, thermal processing, however tends to reduce these beneficial properties especially estrogen hormone and flavor. To overcome this limitation, this study therefore aimed to clarified and sterilized coconut water using non–thermal processing, membrane filtration. Hollow fiber microfiltration (MF) membrane with pore size of 0.1 and 0.2 μm and ultrafiltration (UF) membrane with molecular weight cut–off (MWCO) of 100 and 30 kDa were used. The effect of membrane pore size and MWCO on quality of clarified juice, permeate flux and fouling were studied. It was found that fresh coconut water and clarified coconut water obtained from MF and UF did not show difference in pH, total soluble solid, reducing sugar, estrogen hormone and minerals including calcium, magnesium, phosphorus, potassium and sodium. The results from microbiological analysis of the clarified coconut water showed that sterilized of coconut water was obtained using either MF or UF membranes. This microbiological quality of clarified coconut water was met the Thai legislation for juice and drinks. The permeate flux of MF was much higher than those of UF while the fouling resistance of UF membrane was much higher than those of MF membrane. The permeate flux of membrane with pore size of 0.1 £gm was slightly lower than that of membrane with pore size of 0.2 μm. The results also indicated that the major fouling of both MF and UF membranes was reversible. The irreversible fouling resistance of 0.1 μm membrane was the lowest and most of this irreversible fouling was external irreversible fouling, formed on the membrane surface. According to these results, it could be concluded that 0.1 μm membrane was the most suitable membrane for clarification and sterilization of coconut water. In addition, the effects of TMP, cross flow velocity (CFV) and the % recovery on permeate flux in batch concentration mode were also studied. It was found that the permeate flux of 0.1 μm membrane was significantly increased with increasing CFV and decreased as % recovery increased. These results suggested that permeate flux during MF of coconut water was dependent on reversible fouling and could be improved by using hydrodynamic modification techniques.
Firing properties of ventral medullary respiratory neurons in sino‐aortic denervated rats
Authors: Amorim Mateus R. , Pena Rodrigo F. O. , Souza George M. P. R. , Bonagamba Leni G. H. , Roque Antônio C. , Machado Benedito H.
Published: November 2018

New Findings

What is the central question of this study?

After sino‐aortic denervation (SAD), rats present normal levels of mean arterial pressure (MAP), high MAP variability and changes in breathing. However, mechanisms involved in SAD‐induced respiratory changes and their impact on the modulation of sympathetic activity remain unclear. Herein, we characterized the firing frequency of medullary respiratory neurons after SAD.

What is the main finding and its importance?

Sino‐aortic denervation‐induced prolonged inspiration was associated with a reduced interburst frequency of pre‐inspiratory/inspiratory neurons and an increased long‐term variability of late inspiratory neurons, but no changes were observed in the ramp‐inspiratory and post‐inspiratory neurons. This imbalance in the respiratory network might contribute to the modulation of sympathetic activity after SAD.

In previous studies, we documented that after sino‐aortic denervation (SAD) in rats there are significant changes in the breathing pattern, but no significant changes in sympathetic activity and mean arterial pressure compared with sham‐operated rats. However, the neural mechanisms involved in the respiratory changes after SAD and the extent to which they might contribute to the observed normal sympathetic activity and mean arterial pressure remain unclear. Here, we hypothesized that after SAD, rats present with changes in the firing frequency of the ventral medullary inspiratory and post‐inspiratory neurons. To test this hypothesis, male Wistar rats underwent SAD or sham surgery and 3 days later were surgically prepared for an in situ experiment. The duration of inspiration significantly increased in SAD rats. During inspiration, the total firing frequency of ramp‐inspiratory, pre‐inspiratory/inspiratory and late‐inspiratory neurons was not different between groups. During post‐inspiration, the total firing frequency of post‐inspiratory neurons was also not different between groups. Furthermore, the data demonstrate a reduced interburst frequency of pre‐inspiratory/inspiratory neurons and an increased long‐term variability of late‐inspiratory neurons in SAD compared with sham‐operated rats. These findings indicate that the SAD‐induced prolongation of inspiration was not accompanied by alterations in the total firing frequency of the ventral medullary respiratory neurons, but it was associated with changes in the long‐term variability of late‐inspiratory neurons. We suggest that the timing imbalance in the respiratory network in SAD rats might contribute to the modulation of presympathetic neurons after removal of baroreceptor afferents.
A Novel Nanoelectromagnetic System Using Multiferroic/Magnetoelectric Ni-Nano-Chevron/PMN-PT Heterostructure to Demonstrate an Electric-Field-Controlled Permanent Magnetic Single-Domain Transformation
Authors: Cheng Chih-Cheng , Lin Shin-Hung , Chen Yu-Jen , Wang Hsin-Min , Chu Hou-Jen , Hung Chiao-Fang , Lin Po-Jung , Chung Tien-Kan
Published: November 2018

In this paper, we report a novel nanoelectromagnetic system using multiferroic/magnetoelectric Ni-nano-chevron/PMN-PT heterostructure to demonstrate an electric-field-controlled permanent magnetic single-domain transformation. The heterostructure consists of a magnetostrictive Ni-nano-chevron, Pt top and bottom electrodes, and a piezoelectric PMN-PT substrate. In initial state (as demagnetized), the magnetization of the magnetic single-domain is stably along the long axis of the nano-chevron. A magnetic field of 3000 Oe (along 45 degree of nano-chevron) is applied to magnetize the Ni-nano-chevron from stable single-domain to metastable two-domains. After this, an electric field of 0.8MV/m is applied to the PMN-PT substrate to produce the converse magnetoelectric effect to transform the two-domains. After the electric field is removed, the two-domains are further transformed back to the single-domain. Finally, when comparing the domains before and after applying our approach, approximately 50 % of single-domains are successfully and permanently switched (i.e., magnetization-direction is permanently rotated 180 degrees).
Stress Distributions in an Elastic Body due to Molecular Interactions Considering One-Dimensional Periodic Material Distribution Based on Mindlin Solution
Authors: Matsuoka Hiroshige , Otani Toshiki , Fukui Shigehisa
Published: November 2018

A method to calculate the stress distributions in the elastic body caused by the molecular interactions has been established. The stress distribution was calculated based on the Mindlin’s solution considering the one-dimensional periodic material distribution. The calculation results for a distribution of two materials were presented. The basic characteristics of the stress distribution in the elastic body were quantitatively clarified.
Investigation of the Contact Potential of the Head-Disk Interface Using Kelvin Probe Measurements
Authors: Trinh Tan D. , Spada Frederick E. , Ovcharenko Andrey , Talke Frank E.
Published: November 2018

The contact potential across the head-disk interface is investigated. AC voltage was applied to the disk surface using a mercury connector located at the top of the spindle, keeping the recording head grounded. The acoustic emission (AE) and touchdown sensor (TDS) amplitude was measured as a function of the DC offset voltage to determine the contact potential across the head-disk interface at which the AE and TDS signals, respectively, becomes a minimum. The contact potential across the head-disk interface is studied as a function of temperature, relative humidity, and wear of the head-disk interface.
Active-Contracting Variable-Stiffness Fabrics for Self-Fitting Wearables
Authors: Eschen Kevin , Abel Julianna , Granberry Rachael , Holschuh Brad
Published: November 2018

Self-fitting is the ability of a wearable, garment or body-mounted object to recover the exact shape and size of the human body. Self-fitting is highly desirable for wearable applications, ranging from medical and recreational health monitoring to wearable robotics and haptic feedback, because it enables complex devices to achieve accurate body proximity, which is often required for functionality. While garments designed with compliant fabrics can easily accomplish accurate fit for a range of body shapes and sizes, integrated actuators and sensors require fabric stiffness to prevent drift and deflection from the body surface. This paper merges smart materials and structures research with anthropometric analysis and functional apparel methodologies to present a novel, functionally gradient self-fitting garment designed to address the challenge of achieving accurate individual and population fit. This fully functional garment, constructed with contractile SMA knitted actuator fabrics, exhibits tunable %-actuation contractions between 4–50%, exerts minimal on-body pressure (≤ 1333Pa or 10 mmHg), and can be designed to actuate fully self-powered with body heat. The primary challenge in the development of the proposed garment is to design a functionally gradient system that does not exert significant pressure on part of the leg and/or remain oversized in others. Our research presents a new methodology for the design of contractile SMA knitted actuator garments, describes the manufacture of such self-fitting garments, and concludes with an experimental analysis of the garment performance evaluated through three-dimensional marker tracking.
A Multi-Point Loaded Piezocomposite Beam: Experiments on Sensing and Vibration Energy Harvesting
Authors: Heaney Patrick S. , Bilgen Onur
Published: November 2018

A common configuration for a piezoelectric vibration energy harvester is the cantilevered beam with the piezoelectric device located near the beam root to maximize energy transduction. The beam curvature in this configuration is monotonically decreasing from root to tip, so the transduction per unit length of piezoelectric material decreases with increasing patch length. As an alternative to such conventional configuration, this paper proposes a so-called inertial four-point loading for beam-like structures. The effects of support location and tip mass on the beam curvature shapes are analyzed for four-point loaded cases to demonstrate the effect of these configurations on the total strain induced on the piezoelectric patch. These configurations are tested experimentally using several different support locations and compared with results from a baseline cantilevered beam. Performance comparisons of their power ratios are made, which indicate improvement in the transduction per unit strain of the four-point loading cases over the cantilevered configuration. The paper concludes with a discussion of potential applications of the inertial four-point loaded configuration.
The Ferroelectricity and Crystallinity of Zirconia, Hafnia and Hafnium Zirconium Oxide (HZO) Ultrathin Films Prepared by Atomic Layer Deposition With and Without Post-Annealing
Authors: Hsu Tzu-Yao , Lin Bo-Ting , Shieh Jay , Chen Miin-Jang
Published: November 2018

Large stable ferroelectricity in hafnium zirconium oxide (HZO) solid solution ultrathin films (including pure zirconia (ZrO2) and hafnia (HfO2)) and ZrO2/HfO2 bilayer ultrathin films of thickness ranging from 5–12 nm, prepared by thermal atomic layer deposition or remote plasma atomic layer deposition (RP-ALD) has been demonstrated. Ferroelectric crystallization of the ZrO2 ultrathin film with high-pressure orthorhombic (o) space group Pbc21 could be achieved without post-annealing due to the plasma-induced thermal stresses experienced by the film during the RP-ALD process. In contrast, for the ZrO2/HfO2 bilayer ultrathin film, due to the high crystallization temperature of HfO2, post-annealing was needed to achieve sufficient confinement of the sandwiched HfO2 layer by the ZrO2 top layer and Si bottom substrate to promote the high-pressure ferroelectric o-phase in HfO2. The ferroelectric properties of the HZO ultrathin films prepared by RP-ALD were highly dependent on the Hf-to-Zr ratio — an increasing amount of HfO2 has been found to be detrimental to the ferroelectricity, mainly due to the high crystallization temperature of HfO2. Without post-annealing, the ferroelectricity of the HZO ultrathin films was governed by the relative amounts of the amorphous phase and the ferroelectric o-phase induced by the plasma treatment. While with post-annealing, the ferroelectricity was governed by the relative amounts of the ferroelectric o-phase and the non-ferroelectric monoclinic (m) phase.
On the Use of Piezoelectric Nonlinear Energy Sink for Vibration Isolation and Energy Harvesting
Authors: Xiong Liuyang , Tang Lihua , Liu Kefu , Mace Brian R.
Published: November 2018

Nonlinear energy sink (NES) is employed to passively reduce vibration transmission in this study. A two-degree-of-freedom system, comprising a primary structure coupled with a grounded piezoelectric NES possessing essential nonlinearity, is investigated for both harmonic force excitation and base excitation. The piezoelectric NES acts as not only a vibration isolator but also an energy harvester when connected to an alternating current circuit. Approximate analysis is carried out by the harmonic balance method and validated by numerical solutions using ODE45 in Matlab and equivalent circuit simulation. The effectiveness of the nonlinear vibration isolation system is evaluated by the force (displacement) transmissibility defined as the root-mean-square ratio of transmitted force (displacement) to the excitation force (displacement), which is compared with that of its linear counterparts. Output voltage of the piezoelectric transducer is also derived. By and large, it is found that the piezoelectric NES could reduce the force (displacement) transmissibility while collecting electric energy efficiently in a relatively broad frequency range.
Fabrication and Testing of Kirigami-Inspired Multi-Stable Composites
Authors: Lele Aditya , Myers Oliver J. , Li Suyi
Published: November 2018

This paper aims at highlighting the fabrication procedures and proof-of-concept tests of a Kirigami inspired multi-stable composite laminate. Bistable composites consisting of asymmetric fiber layout have shown great potentials for shape morphing and energy harvesting applications. However, a patch of such a bistable composite is limited to very simple deformation when being snapped between its two stable equilibria (or states). To address this issue, this study investigates the idea of utilizing Kirigami, the ancient art of paper cutting, into the design and fabrication of bistable composite laminates. Via combining multiple patches of laminates and cutting according to prescribed Kirigami pattern, one can create a structure with multiple stable states and sophisticated deformation paths between them. This can significantly expand the application potentials of the multi-stable composites. This paper details the fabrication procedures for an elementary unit cell in the envisioned Kirigami composite and the results of proof-of-concept experiments, which measure the force required to switch the Kirigami composite between its different stable states. Preliminary results confirm that the Kirigami unit cell possesses multiple stable states depending on the underlying fiber layout. Each patch in the Kirigami composite could be snapped independently between stable states without triggering any undesired snapping in other patches. Moreover, a transient propagation of curvature change is observed when a patch in the Kirigami composite is snapped between its stable states. Such a phenomenon has not been reported in the bistable composite studies before. Results of this paper indicate that Kirigami is a powerful approach for designing and fabricating multi-stable composites with a strong appeal for morphing and adaptive systems. This paper highlights the feasibility and novelty of combining Kirigami art and bistable adaptive composites.
Elastocaloric Cooling: System Design, Simulation, and Realization
Authors: Welsch Felix , Kirsch Susanne-Marie , Michaelis Nicolas , Motzki Paul , Schmidt Marvin , Schütze Andreas , Seelecke Stefan
Published: November 2018

Elastocaloric cooling is a novel environment-friendly alternative to vapor compression-based cooling systems. This solid-state cooling technology uses NiTi shape memory alloys (SMAs) as cooling medium. SMAs are well known for lightweight actuator systems and biomedical applications, but in addition, these alloys exhibit excellent cooling properties. Due to the high latent heats activated by mechanical loading/unloading, large temperature changes can be generated in the material. Accompanied by a small required work input, this also leads to a high coefficient of performance superior to vapor compression-based systems. In order to access the potential of these alloys, the development of suitable thermodynamic cooling cycles and an efficient system design are required. This paper presents a model-based design process of an elastocaloric air-cooling device. The device is divided into two parts, a mechanical system for continuously loading and unloading of multiple SMA wire bundles by a rotary motor and a heat transfer system. The heat transfer system enables an efficient heat exchange between the heat source and the SMA wires as well as between the SMA wires and the environment. The device operates without any additional heat transfer medium and cools the heat source directly, which is an advantage in comparison to conventional cooling systems. The design of this complex device in an efficient manner requires a model approach, capable of predicting the system parameters cooling power, mechanical work and coefficient of performance under various operating conditions. The developed model consists of a computationally efficient, thermo-mechanically coupled and energy based SMA model, a model of the system kinematics and a heat transfer model. With this approach, the complete cooling system can be simulated, and the required number of SMA wires as well as the mechanical power can be predicted in order to meet the system requirements. Based on the simulation results a first prototype of the elastocaloric cooling system is realized.
A Chemo-Mechatronic Origami Device for Chemical Sensing
Authors: Liu Chang , Gomes Conor M. , McDonald Kevin J. , Deravi Leila F. , Felton Samuel M.
Published: November 2018

This paper presents the design, fabrication, and operation of a chemo-mechatronic system that changes its geometry and electrical functionality in the presence of specific chemical signals. To accomplish this, we integrated a protein hydrogel with an aluminum substrate and flexible circuit in a low-profile laminate. To demonstrate the concept, we have built and tested a sensor that lights an LED when actuated in the presence of polyethylene glycol (PEG).
Validation of Impedance-Based Structural Health Monitoring in a Simulated Biomedical Implant System
Authors: Ponder Robert I. , Safaei Mohsen , Anton Steven R.
Published: November 2018

Total Knee Replacement (TKR) is an important and in-demand procedure for the aging population of the United States. In recent decades, the number of TKR procedures performed has shown an increase. This pattern is expected to continue in the coming decades. Despite medical advances in orthopedic surgery, a high number of patients, approximately 20%, are dissatisfied with their procedure outcomes. Common causes that are suggested for this dissatisfaction include loosening of the implant components as well as infection. To eliminate loosening as a cause, it is necessary to determine the state of the implant both intra- and post-operatively. Previous research has focused on passively sensing the compartmental loads between the femoral and tibial components. Common methods include using strain gauges or even piezoelectric transducers to measure force. An alternative to this is to perform real-time structural health monitoring (SHM) of the implant to determine changes in the state of the system. A commonly investigated method of SHM, referred to as the electromechanical impedance (EMI) method, involves using the coupled electromechanical properties of piezoelectric transducers to measure the host structure’s condition. The EMI method has already shown promise in aerospace and infrastructure applications, but has seen limited testing for use in the biomechanical field. This work is intended to validate the EMI method for use in detecting damage in cemented bone-implant interfaces, with TKR being used as a case study to specify certain experimental parameters. An experimental setup which represents the various material layers found in a bone-implant interface is created with various damage conditions to determine the ability for a piezoelectric sensor to detect and quantify the change in material state. The objective of this work is to provide validation as well as a foundation on which additional work in SHM of orthopedic implants and structures can be performed.
Can Quantum Computers Solve Linear Algebra Problems to Advance Engineering Applications?
Authors: Xu Guanglei , Oates William S.
Published: November 2018

Since its inception by Richard Feynman in 1982, quantum computing has provided an intriguing opportunity to advance computational capabilities over classical computing. Classical computers use bits to process information in terms of zeros and ones. Quantum computers use the complex world of quantum mechanics to carry out calculations using qubits (the quantum analog of a classical bit). The qubit can be in a superposition of the zero and one state simultaneously unlike a classical bit. The true power of quantum computing comes from the complexity of entanglement between many qubits. When entanglement is realized, quantum algorithms for problems such as factoring numbers and solving linear algebra problems show exponential speed-up relative to any known classical algorithm. Linear algebra problems are of particular interest in engineering application for solving problems that use finite element and finite difference methods. Here, we explore quantum linear algebra problems where we design and implement a quantum circuit that can be tested on IBM’s quantum computing hardware. A set of quantum gates are assimilated into a circuit and implemented on the IBM Q system to demonstrate its algorithm capabilities and its measurement methodology.
Towards High Turndown Ratio Shape Memory Alloy-Driven Morphing Radiators
Authors: Walgren Patrick , Benafan Othmane , Erickson Lisa , Hartl Darren
Published: November 2018

Future manned space missions will require thermal control systems that can adapt to larger fluctuations in temperature and heat flux that exceed the capabilities of current state-of-the-art systems. These missions will demand novel space radiators that can vary the heat rejection rate of the system to maintain the crew cabin at habitable temperatures throughout the entire mission. Current systems can provide a turndown ratio (defined as the ratio of maximum to minimum heat rejection) of 3:1 under adverse conditions. However, future missions are projected to demand thermal control systems that can provide a turndown ratio of more than 6:1. A novel radiator concept, known as the morphing radiator, varies the system heat rejection rate by altering the shape of the radiator that is exposed to space. This shape change is accomplished through the use of shape memory alloys, a class of active materials that exhibit thermomechanically-driven phase transformations and can be used as both sensors and actuators in thermal control applications. In past efforts, prototype morphing radiators have been tested in a relevant thermal environment, demonstrating the feasibility and scalability of the concept. This work summarizes the progress towards testing a high-performance morphing radiator in a relevant thermal environment and details the development of an efficient numerical model that predicts the mechanical response of an arbitrary morphing radiator configuration due to changes in temperature. Model predictions are then validated against previous experimental results, demonstrating the usefulness of the model as a design tool for future morphing radiator prototypes.
Nonlocal Buckling Characteristics of Functionally Graded Nano-Plates Subjected to Thermal Loads and Biaxial Linearly Varying Forces
Authors: Sari Ma’en S. , Ghaffari Seyedeh Sepideh , Ceballes Samantha , Abdelkefi Abdessattar
Published: November 2018

The buckling characteristics of thin functionally graded (FG) nano-plates subjected to both thermal loads and biaxial linearly varying forces is investigated. Eringen’s nonlocal elasticity theory is employed to account for the nano-scale phenomena in the plates. Hamilton’s principle and the constitutive relations are used to derive the partial differential governing equations of motion for the thin plates that are modeled using Kirchhoff’s plate theory. The mechanical properties of the FG nano-plates are assumed to vary smoothly across the thickness of the plate following a power law. Three types of thermal loads are presented and the spectral collocation method is utilized to solve for the critical buckling loads. The accuracy of the numerical solution of the proposed model is verified by comparing the results with those available in the literature. A comprehensive parametric study is carried out, and the effects of the nonlocal scale parameter, power law index, aspect ratio, slopes of the axial loads, boundary conditions, assumed temperature distributions, and the difference between the ceramic-rich and metal-rich surfaces on the nonlocal critical buckling loads of the nano-plates are examined. The results reveal that these parameters have significant influence on the stability behavior of the FG nano-plates.
Linear Parameter Varying Modeling and Estimation of a SMA Wire Actuator
Authors: Kubik Kyle , Gurley Austin , Beale David , Skalitzky Amanda
Published: November 2018

Shape Memory Alloys (SMAs) actuators operate via a nonlinear and hysteretic relationship between input power and mechanical motion. This nonlinearity presents a serious challenge when developing methods for controlling these actuators. Because this hysteresis and nonlinearity is caused by the crystal phase transformation however, the SMA constitutive and kinetic models can be written in Linear Parameter Varying (LPV) form, with the partial derivative of crystal phase fraction with respect to temperature as the varying parameter. This allows a SMA system to be written in a state-space format where the coefficients in the state matrices vary as a function of the state variables, allowing for the application of powerful linear system analysis tools to this model without simplifying assumptions. This LPV model can then be used to create an estimator for the system, allowing for real-time approximations of the system states, including temperature and phase fraction. This paper presents the derivation of one such LPV model and explores its ability to accurately represent a physical SMA actuator system by comparison with an instrumented SMA muscle system.
Experimental Exploration of Post Constrained Recovery Mechanics of NiTi
Authors: Haider Muhammad Istiaque , Correa Ameralys , Moghadam Afsaneh , Yan Xiaojun , Salowitz Nathan
Published: November 2018

Shape memory alloys (SMAs) have tremendous potential use as actuators in mechanical systems due to their high specific energy density. Large recovery stresses can be generated when Nickel Titanium (NiTi), the most widely used SMA, undergoes constrained recovery where it is held in a deformed geometry and heated from a detwinned martensite phase to austenite phase. Recent experimental results have found that residual stresses can also be generated in NiTi after returning to a low temperature geometrically constrained state. This paper presents experimental results performed on NiTi wire samples where wire was: 1) deformed from a low temperature twinned martensite state to produce a strain that would be recoverable in an unloaded state 2) held at that strain state and heated above the austenite finish transition temperature and then cooled back below the martensite transition finish temperature while recording the forces generated. It was found that a residual load was produced in the low temperature state. Results from further testing beyond this point showed repeatability with application of small and large strains. Post constrained recovery stresses have the potential to be used to generate residual stresses in structures in a low energy, un-actuated state with a remaining potential for thermal actuation.
A Leading-Edge Alula-Inspired Device (LEAD) for Stall Mitigation and Lift Enhancement for Low Reynolds Number Finite Wings
Authors: Ito Mihary R. , Duan Chengfang , Chamorro Leonardo P. , Wissa Aimy A.
Published: November 2018

Even though Unmanned Aerial Vehicles (UAVs) operating at low Reynolds numbers are becoming common, their performance and maneuverability are still greatly limited due to aerodynamic phenomena such as stall and flow separation. Birds mitigate these limitations by adapting their wings and feather shapes during flight. Equipped with a set of small feathers, known as the alula, located near the leading edge and covering 5% to 20% of the span, bird wings can sustain the lift necessary to fly at low velocities and high angles of attack. This paper presents the effect on lift generation of different placements of a Leading-Edge Alula-inpsired Device (LEAD) along the span of a moderate aspect-ratio wing. The device is modeled after the alula on a bird, and it increases the capability of a wing to maintain higher pressure gradients by modifying the near-wall flow close to the leading-edge. It also generates tip vortices that modify the turbulence on the upper-surface of the wing, delaying flow separation. The effect of the LEAD can be compared to traditional slats or vortex generators on two-dimensional wings. For finite wings, on the other hand, the effect depends on the interaction between the LEADs tip vortices and those from the main structure. Wind tunnel experiments were conducted on a cambered wing at post-stall and deep-stall angles of attack at low Reynolds numbers of 100,000 and 135,000. To quantify the aerodynamic effect of the device, the lift generated by the wing with and without the LEAD were measured using a 6-axis force and torque transducer, and the resulting lift coefficients were compared. Results show that the location of the LEAD yielding the highest lift enhancement was 50% semi-span away from the wing root. Lift improvements of up to 32% for post stall and 37% for deep stall were obtained at this location, demonstrating that the three-dimensional effects of the LEAD are important. The lift enhancement was also more prominent on a finite moderate aspect-ratio wing (3D) than on an airfoil (2D), confirming that the LEAD is a three-dimensional device. Identifying the configurations and deployment parameters that improve lift generation the most is needed to design an adaptive LEAD that can be implemented on a UAV wing for increased mission-adaptability.
In Vivo Energy Harvesting Using Cardiomyocytes for Implantable Medical Devices
Authors: Karami M. Amin
Published: November 2018

One major problem of implantable biomedical devices is the source of their power. Batteries, as the main source of current implantable devices, deplete after a few years and either the battery or the whole device needs to be replaced. Usually, this procedure involves a new surgery which is costly and could cause some risks for the patient. In this paper, we study the energy harvesting at small scale for powering implantable biomedical devices. The device consists of a layer of cultured cardiac muscle cells (cardiomyocytes) and a layer of piezoelectric polymer polyvinylidene fluoride (PVDF). The cardiac muscle cells with the desired thickness are grown over the PVDF layer and as the cardiac cells contract the piezoelectric layer deforms and produces electricity. The proposed device uses both piezoelectric and flexoelectric effects of the PVDF layer. At the smaller thicknesses the flexoelectric effect becomes dominant. The amount of power is on the order of multiple microwatts and is sufficient to power variety of sensors and implantable devices in the body. Unlike the battery technology, the proposed energy harvester is autonomous and lasts for the lifetime of patients. In this article, we explain the configuration of the proposed energy harvester, the natural frequency of the device is calculated, the power output is optimized with respect to the thickness of the PVDF, and a resistance sweep is performed to find the optimized resistive load.
Dangerous Scenes Recognition During Hoisting Based on Faster Region-Based Convolutional Neural Network
Authors: Su Hongguo , Zhang Mingyuan , Li Shengyuan , Zhao Xuefeng
Published: November 2018

In the last couple of years, advancements in the deep learning, especially in convolutional neural networks, proved to be a boon for the image classification and recognition tasks. One of the important practical applications of object detection and image classification can be for security enhancement. If dangerous objects or scenes can be identified automatically, then a lot of accidents can be prevented. For this purpose, in this paper we made use of state-of-the-art implementation of Faster Region-based Convolutional Neural Network (Faster R-CNN) based on the monitoring video of hoisting sites to train a model to detect the dangerous object and the worker. By extracting the locations of them, object-human interactions during hoisting, mainly for changes in their spatial location relationship, can be understood whereby estimating whether the scene is safe or dangerous. Experimental results showed that the pre-trained model achieved good performance with a high mean average precision of 97.66% on object detection and the proposed method fulfilled the goal of dangerous scenes recognition perfectly.
Preliminary Failure Analysis and Structural Design of a Morphing Winglet for Green Regional Aircraft
Authors: Dimino Ignazio , Ameduri Salvatore , Concilio Antonio
Published: November 2018

Aircraft wing design optimization typically requires the consideration of many competing factors accounting for both aerodynamics and structures. To address this, research on morphing aircraft has shown its potential by providing large benefits on aircraft performance. In particular, by adapting wing lift distribution, morphing winglets are capable to improve aircraft aerodynamic efficiency in off-design conditions and reduce wing loads at critical flight points. For those reasons, it is expected that these devices will be applied to the aircraft of the very next generation. In the study herein presented, a preliminary failure analysis and structural design of a morphing winglet are presented. The research is collocated within the Clean Sky 2 Regional Aircraft IADP, a large European programme targeting the development of novel technologies for the next generation regional aircraft. The safety-driven design of the proposed kinematic system includes a thorough examination of the potential hazards associated with the system faults, by taking into account the overall operating environment and functions. The mechanical system is characterized by movable surfaces sustained by a winglet skeleton and completely integrated with a devoted actuation system. Such a load control device requires sufficient operational reliability to operate on the applicable flight load envelope in order to match the needs of the structural design. One of the most critical failure modes is assessed to get key requirements for the system architecture consistency. Possible impacts of the defined morphing outline on the FHA analysis are investigated. The structural design process is then addressed in compliance with the demanding requirements posed by the implementation on regional airplanes. The layout static robustness is verified by means of linear stress analyses at the most critical conditions, including possible failure scenarios. Results focus on the assessment of the device static and dynamic structural response and the preliminary definition of the morphing system kinematics, including the integrated actuator system.
NUCLEOs: Toward Rapid-Prototyping of Robotic Materials That Can Sense, Think and Act
Authors: Ayad Mustafa , Nawrocki Robert , Voyles Richard M. , Lee Junseok , Lee Hyowon , Leon-Salas Daniel
Published: November 2018

Robotic Materials are materials that have sensing, computation and, possibly actuation, distributed throughout the bulk of the material. In such a material, we envision semiconducting polymer based sensing, actuation, and information processing for on-board decision making to be designed, in tandem, with the smart product that will be implemented with the smart material. Prior work in printing polymer semiconductors for sensing and cognition have focused on highly energetic inkjet printing. Alternatively, we are developing liquid polymer extrusion processes to work hand-in-hand with existing solid polymer extrusion processes (such as Fused Deposition Manufacturing - FDM) to simultaneously deposit sensing, computation, actuation and structure. We demonstrate the successful extrusion printing of conductors and capacitors to impedance-match a new, higher-performance organic transistor design that solves the cascading problem of the device previously reported and is more amenable to liquid extrusion printing. Consequently, these printed devices are integrated into a sheet material that is folded into a 3-D, six-legged walking machine with attached electric motor.