bluuebunny/crossref_metadata_2025 huggingface dataset:
A Linear-Element Coupled Nonlinear Energy Harvesting System
Authors: Zhou Shengxi , Inman Daniel J. , Cao Junyi
Published: January 2016

This paper presents a linear-spring coupled nonlinear energy harvesting system, which contains linear piezoelectric energy harvesters coupled by linear springs. Although every element of the system is linear, the system will present nonlinear characteristics when it is subjected to excitations because of the geometric nonlinearity induced by coupled motions. Three non-uniform cross-section linear harvesters with the same total length and the different thickness are selected to form the proposed system. Based on Euler-Bernoulli beam assumptions and the geometrical relationship among each element, a detailed modeling process of the proposed system is presented. In order to verify the broadband characteristics, the comparison of the proposed system and its linear counterparts is provided. Under harmonic excitations, the proposed system has much better energy harvesting capacity compared with its linear counterparts. What’s more, the energy harvesting performance of the proposed system is a little better than its linear counterparts under random excitations. The results demonstrate that the advantage of the proposed system is enhanced along with increased excitation level. In addition, such non-magnetic nonlinear energy harvesting system can be used in the areas where magnets are forbidden, such as inside the human body.
Modeling the Electric Field-Guided Motion of Interacting Carbon Nanotubes Using a Dielectrophoretic Framework
Authors: Oliva-Avilés A. I. , Avilés F. , Zozulya V. V.
Published: January 2016

A theoretical investigation of the dynamic response of a pair of interacting carbon nanotubes (CNTs) dispersed in a liquid medium under the presence of an alternating current (AC) electric field is presented. The proposed modeling strategy is based on the dielectrophoretic (DEP) theory and classical electrodynamics, and considers the effect of an applied AC electric field on the rotational and translation motion of interacting CNTs represented as electrical dipoles. The mutual interaction between a pair of adjacent CNTs stems from the presence of DEP-induced charges on the CNTs and, as such, contributes to the rotational and translational dynamics of the system. Based on experimental evidence, the parameters which are expected to cause a major contribution to the CNTs motion are investigated for different initial configurations. Based on the obtained results, it is here predicted that high electric field frequencies, long CNTs, high values of electrical permittivity and conductivity of CNTs immersed in solvents of high polarity promote faster rotational and translational motion and therefore faster equilibrium conditions (CNT tip-to-tip contact and horizontal alignment). The results incorporate important knowledge towards a better understanding of the complex mechanisms involved in the efforts of tailoring CNT networks by electric fields.
Elastocaloric Cooling With Ni-Ti Based Alloys: Material Characterization and Process Variation
Authors: Schmidt Marvin , Ullrich Johannes , Wieczorek André , Frenzel Jan , Schütze Andreas , Eggeler Gunther , Seelecke Stefan
Published: January 2016

Solid state refrigeration processes, such as magnetocaloric and electrocaloric refrigeration, have recently shown to be a promising alternative to conventional compression refrigeration. A new solid state elastocaloric refrigeration process using the latent heats within Shape Memory Alloys (SMA) could also hold potential in this field. This work investigates the elastocaloric effects in Ni-Ti-based superelastic Shape Memory Alloy (SMA) systems for use in an elastocaloric cooling processes. Ni-Ti alloys exhibits large latent heats and a small mechanical hysteresis, which may potentially lead to the development of an efficient environmentally friendly solid-state cooling system, without the need for ozone-depleting refrigerants. A systematic investigation of the SMA is conducted using a novel custom-built scientific testing platform specifically designed to measure cooling process related phenomena. This testing system is capable of performing tensile tests at high rates as well as measuring and controlling the solid-state heat transfer between SMA and heat source/heat sink.

Tests are conducted following a cooling process related training cycle where the material has achieved stabilized behavior. First, a characterization of the elastocaloric material properties is performed followed by an investigation of the material under cooling process conditions.

A comprehensive monitoring of the mechanical and thermal parameters enables the observation of temperature changes during mechanical cycling of the SMA at high strain rates. These observations can be used to study the rate dependent efficiency of the elastocaloric material.

The measurement of the temperature of both the heat source/heat sink and the SMA itself, as well as the required mechanical work during a running cooling process, reveals the influence of the operating conditions on the elastocaloric effect of the material.

Furthermore investigations of the process efficiency at different thermal boundary conditions (temperature of heat source/heat sink), indicates that the process is dependent on the boundary conditions which have to be controlled in order to optimize the efficiency.
Coupled Damage Precursor Detection
Authors: Myers Oliver J. , Banerjee Sourav
Published: January 2016

This conceptual research focuses on identifying damage precursors in carbon fiber reinforced polymer laminates. By coupling integrated in situ sensing elements (magnetostrictive particles) and multi-scale ultrasonic inspection (Quantitative Ultrasonic Imaging) with minimum hardware the authors are able to capture and gain an understanding of damage precursors. Preliminary damage precursors can be identified and quantified and correlated to a particular failure mode(s) and/or fabrication process accelerating the need for a sensing/repair strategy that could be implemented to capture the specific precursor prior to the onset of cracks. Capturing and mitigating damage precursors ahead of micro-crack formulation will slow the evolution of the damage precursors to micro-cracks, mitigate adverse loading environment, and develop techniques to reduce stress and loading below the endurance limit to keep it from being fatigued.
Identification of Nodal Snap-Through Instability in Civil Space Structures
Authors: Yan Guirong , Duan Qiuhua , Feng Ruoqiang
Published: January 2016

In the community of structural health monitoring (SHM) and damage detection, the majority of previous research efforts has been focused on the detection of the reduction in cross-sectional areas of structural components or connections. However, the detection of the loss of stability, which can easily result in a structural failure, has been lacking. The objective of this study is to identify the occurrence of instability in civil space structures, such as domes, shells and reticulated shell structures. For this type of structure, nodal snap-through instability occurs, where a node and connected members jump to a new equilibrium position, leading the geometric shape/pattern in a local area to change significantly. In this study, we propose to use tilting angles of members to identify the nodal snap-through instability of civil space structures. Tilting angles of members actually reflect the change in geometric shape caused by instability. The effectiveness of this approach will be validated on numerical simulations of a reticulated shell structure. This research will bridge the gap between SHM and structural stability research and will make important contributions to the science of both SHM and structural instability.
Detection of Pretension Loss of Cable-Net Structures
Authors: Yan Guirong , Jemison Scott , Duan Qiuhua , Feng Ruoqiang
Published: January 2016

Due to aesthetic shapes, light weight and flexibility, cable-net structures have been widely used as roofs for venues where many people assemble, such as sports stadiums/arenas and gymnasiums. Failure of this type of structure may endanger the safety of many people. This type of structure consists of a separate grid of structural cables supporting a nonstructural weather shield. It is well known that the stiffness of this type of structure is established by pretension in the cables. Part of the pretension in the cables will be lost as time evolves. The detection of the pretension loss in cables of cable-stayed bridges has been widely studied. However, the detection of pretension loss in cables of cable-net structures has been lacking. In this study, the dynamic and static properties of cable-net structures will be investigated and the effectiveness of two damage detection approaches in detecting the pretension loss in cable-net structures will be investigated.
Combined Simulation of the Closing Behavior of a Smart Hydrogel Micro-Valve
Authors: Mehner Philipp J. , Allerdißen Merle , Voigt Andreas , Marschner Uwe , Richter Andreas
Published: January 2016

Smart hydrogel micro-valves are essential components of micro-chemo-mechanical fluid systems. These valves show a transistor-like behavior and are based on phase-changeable polymers. They can open and close micro-fluidic channels depending on chemical concentrations in the fluid. These highly complex systems are challenging to engineer and their development will advance faster if proper simulations take place beforehand.

A concept of how to simulate concentration-triggered, phase-changeable hydrogels is proposed. A simplified flow simulations will be presented to demonstrate the feasibility of this approach and to highlight geometrical problems. Based on the results, structurally more advanced models will be introduced with implemented multi-field solver interactions including thermal, mechanical and fluidic domains. The results of these models show the closing behavior of a micro-valve. The computed parameters of such valves are implemented into a circuit representation, which is capable of efficiently computing large scale micro-fluidic systems using an electric circuit simulator. These methods will help to predict, visualize and understand polymeric swelling behavior and demonstrate the performance of large-scale chip applications before any complex experiment is performed.
Comparison of CNT-Papers and CNT-Arrays Regarding Their Active Behavior
Authors: Geier Sebastian M. , Wierach Peter , Mahrholz Thorsten , Sinapius Michael
Published: January 2016

This paper focuses on the actuation mechanisms of CNT-papers and CNT-arrays. CNT-papers represent architectures of CNTs which are connected by van der Waals forces or structural entanglement. In contrast CNT-arrays are vertically aligned CNTs. Single CNTs are favored for investigation of the active behavior of the hexagonal carbon structure formed by covalent C-bonds. CNT-arrays feature contiuous tubes of 3 mm length which allows the test the tubes themselves. Thus they are clamped at each end they represent samples for testing covalent bonds. Both sample types are tested within an actuated tensile test set-up under different conditions to identify the specific influence. Furthermore different electrolytes are used to investigate the influence of the ion-radius on the CNT-paper. CNT-papers are tested in water-based electrolytes CNT-arrays are tested in an ionic liquid. It was found that the performance of CNT-papers strongly depends on the conditions which indicates ion-diffusion as actuation mechanism. However, CNT-arrays are almost unaffected by the conditions, considering their active response and sample composition quantum mechanical reasons seem to be the most appropriate explanation for the array actuation.
Optimal Placement of Negative Stiffness Damping System
Authors: Mathew Gisha Mary , Qureshi Asim , Jangid R. S.
Published: January 2016

Negative stiffness systems have been widely studied for their seismic response reduction characteristics and have been found to be very effective in reducing seismic responses in structures. Based primarily on the concept of introducing flexibility in the structure, they bring about seismic response reduction by reversing the force–deformation behaviour of the structure-device assembly. While some negative stiffness devices alter the physical behaviour of the structure to deformation, some devices show “pseudo negative stiffness” behaviour by means of a control algorithm. To have the best possible reduction of seismic response in structures, it is essential that an optimal combination of dampers is used. The present work studies the performance of true negative system (TNS) and an adaptive negative stiffness system (ANSS) on a 5 degree of freedom shear structure. The optimal values of parameters and optimal number of dampers are studied based on the response such as inter-storey drifts, accelerations, displacements and base shear obtained from MATLAB analysis.
Investigating Piezoelectric Energy Harvesting Circuits for Piezoelectric Flags
Authors: Zargarani Anahita , Mahmoodi Nima
Published: January 2016

This paper provides a comparison between two different energy harvesting circuits for a piezoelectric flag subjected to uniform flow. Between two circuits tested, one is Simple Resistive Load, and the other one is the standard AC-DC circuit. To experimentally investigate these circuits, the piezoelectric flag output voltage has been studied under various wind speeds in a wind tunnel. The simple resistive load circuit provides an alternating voltage, and not a DC voltage. The standard AC-DC circuit is used to convert the AC voltage into a DC voltage; however, the power dropped as a result of the voltage drop across the forward-biased diodes.
Forced Response Analysis of a Piezoelectric Flag Modeled as a Membrane
Authors: Frey Gary , Mahmoodi Nima
Published: January 2016

A piezoelectric flag is modeled as a membrane for energy harvesting purposes. The tension, pressure, piezoelectric material, and external force are introduced and employed in the model. In this model, the tension is caused by gravity, the piezoelectric material, and the fluid flow. The pressure acting on the flag consists of a non-circulatory and a circulatory component. Additionally, an external force is modeled to ensure that the pressure acting on the system does not dissipate. To model the system, Hamilton’s principle is employed to find differential equation of motion. In this study, the flag is vertically oriented. This is to ensure the flag does not droop, which would greatly complicate the effect of gravity. In studying the free response, it is found that the Bessel function of the first kind describes the flag. Lastly, Galerkin’s method is applied to the system. This allows for the deflection and the voltage produced by the flag to be found. It is found that the presented model reasonably predicts both the deflection and voltage of the piezoelectric flag.
Network-Based Active Vibration Control of Collocated Actuator/Sensor Structures via Consensus Positive Position Feedback
Authors: Omidi Ehsan , Mahmoodi Nima
Published: January 2016

Vibration control in smart structures is discussed in this paper using an approach based on connecting collocated control elements to one another via a network with certain topology. Consensus method is implemented to force disagreements between the control agents of the structure to zero, where each control agent consists of a multi-mode Positive Position Feedback (PPF) second-order compensator. Multi-agent state-space representation of actuator/sensor elements is used, accompanied with an optimal state-estimator. The consensus law is embedded in the dynamics of the PPF control elements. Required conditions for stability of the closed-loop multi-agent system are then extracted. Performance of the controller is numerically investigated, and synchronization of controller agents is examined. Significant advantage of the decentralized consensus-based vibration controller over centralized forms is in robustness to failure of components or an entire agent, and obtained synchronized performance of the whole control system.
Reduced Plate Model Used for 2D Traveling Wave Propagation
Authors: Malladi V. V. N. Sriram , Albakri Mohammad , Tarazaga Pablo A. , Gugercin Serkan
Published: January 2016

The focus of this study is to understand traveling wave generation and propagation in reduced order 2D plate models. A plate with all clamped (C-C-C-C) boundary conditions was selected to be the medium through which the wave propagation occurs. The plate is excited at multiple locations by point forces which generates controlled oscillations resulting in net traveling waves. A finite element model is developed and the traveling wave response is simulated. The numerical model is complex with a large number of degrees-of-freedom making a parametric study computationally intensive. In order to overcome this computational burden, balanced truncation based and interpolation-based model reduction techniques are employed to reduce the total number of degrees-of-freedom. The capabilities of these reduction techniques to capture the steady-state frequency-domain characteristics and the steady-state time-domain response have been compared in this paper.
Design and Effective Properties of a Functionally Graded Unidirectional Fiber-Reinforced Composite
Authors: Panda Satyajit
Published: January 2016

The present work deals with the design of a fiber-reinforced composite lamina with varying fiber-volume fraction (FVF) along its thickness direction. In the available elastic analyses of this kind of composite, the elastic properties are evaluated based on the assumptions like continuous variation of FVF and existence of decoupled representative volume element (RVE) at every point along the thickness direction. In order to predict the graded material properties without any of these assumptions at present, first a micro-structure of similar graded composite is designed for the variation of FVF according to a sigmoid function of thickness coordinate. Next, a continuum micro-mechanics finite element model of the corresponding representative volume (RV) is derived. The RV is basically composed of several micro-volumes of different FVFs and the classical homogenization treatment is implemented over these micro-volumes without decoupling them from the overall volume of RV. The importance of this coupled analysis is verified through a parallel decoupled analysis. The effect of the total number of micro-volumes within a specified thickness of lamina on its graded elastic properties is presented. The characteristics of graded elastic properties according to the sigmoid function are also discussed.
A Novel Mechanical-Mechanism Enhanced Thermomagnetic Tweezer Demonstrating Gripping of Ferromagnetic and Non-Ferromagnetic Objects
Authors: Wang Hsin-Min , Chung Tien-Kan , Chen Chin-Chung , Cheng Chih-Cheng , Lin Chu-Yi
Published: January 2016

In this article, we demonstrate a mechanical-mechanism enhanced thermomagnetic tweezer. The tweezer which utilizes a thermal-magnetic-mechanical converting consists of two cross-jointed Al arms, two Gd sheets, two NdFeB hard magnets, two thermoelectric generators (TEGs), and a ball bearing set. When comparing conventional thermomagnetic grippers, our thermomagnetic tweezer can grip either ferromagnetic or non-ferromagnetic objects and avoid producing temperature-influence to the gripped objects. Experimental results show that we can control TEGs to generate a temperature difference to operate the tweezer to grip small ferromagnetic objects (such as NdFeB hard magnet) and other non-ferromagnetic objects (such as PMMA bulk). The maximum gripping force produced by the tweezer operated by applying the DC current of 1.3 A with the voltage of 0.85 V is 0.59 newton. The corresponding gripping and releasing duration is 7.9 seconds and 8.1 seconds, respectively. According to these results, our tweezer would produce more practical objects-gripping applications.
Geometric Effects on Embedded Piezoelectric Energy Harvester in Knee Replacement Bearing
Authors: Contreras Cesar E. , Parkison April E. , Wilson Brooke E. , Meneghini R. Michael , Anton Steven R.
Published: January 2016

Each year in the US, over 700,000 patients receive total knee arthroplasty to restore joint function and improve quality of life. A major challenge during surgery is achieving proper ligamentous balance. Improperly balanced knees can lead to accelerated wear of the articular surfaces, reduced range of motion, and patient discomfort and pain. Currently, surgeons rely heavily on their experience and their interpretation of the “feel” of a balanced knee. The goal of the proposed research is to investigate the use of piezoelectric materials embedded in total knee replacement bearings in order to sense forces in vivo and convert knee loads into usable electrical energy to power the embedded sensor. This paper presents an investigation of the effects of various geometric properties on the performance of piezoelectric transducers embedded into polyethylene knee replacement bearings. This work takes a combined modeling and experimental approach to investigate the effects of the overall bearing geometry as well as placement of the embedded transducers on the performance of the system. A simple cylindrical geometry is chosen to represent the knee bearing in order to isolate various effects. Specifically, the curvature of the upper bearing surface is investigated to determine the effects of different curvature profiles on the voltage output of the embedded transducer. Designs with the smallest diameter of curvature are found to provide increased load transfer to the embedded piezoelectric and larger generated power. Additionally, the radial placement of the embedded piezoelectric device is investigated to determine the performance of the system as the piezoelectric device is translated from the geometric center of the bearing to the outer edge. Results show that optimal performance is obtained for placement near the center of the geometric curved feature. Lastly, the effects of variations in machining and fabrication are investigated and it is found that tight tolerances must be maintained in order to obtain experimental results that can be accurately predicted by the model developed in this work.
Further Insight on the Power Harvesting Capabilities of Magnetic Shape Memory Alloys
Authors: Guiel Roger , Dikes Jason L. , Ciocanel Constantin , Feigenbaum Heidi P.
Published: January 2016

Magnetic shape memory alloys are a relatively new class of materials that are suitable for actuation, sensing, and power harvesting. The power harvesting capability comes from the change in magnetization that the material exhibits when internal martensitic variants change orientation.

In typical power harvesting tests, the material is loaded with axial compression in the presence of a bias magnetic field applied normal to the compressive loading direction. However, previous results suggest that having a component of the bias magnetic field applied axially, parallel to the compressive stress, can increase the power output of MSMAs.

Furthermore, most of the MSMAs power harvesting results reported to date focused on the open circuit voltage that the material can generate during cyclic loading. However, this information is not indicative of the true power harvesting capability of the material and one has to focus on the power output of the material instead.

This paper presents voltage trends and power output data for a MSMA sample exposed simultaneously to a cyclic compressive stress and bi-axial magnetic field.
The Role of Flexibility on Center of Mass Oscillations of Self Propelled Flapping Fins
Authors: Kancharala Ashok K. , Philen Michael K.
Published: January 2016

Flexibility is known to improve the propulsive performance of flapping fins. Flapping fins generate forces oscillatory in nature and this paper reports an investigation on the effect of flexibility and other parameters such as heaving, pitching amplitudes and operating frequency in reducing the center of mass oscillations of bodies attached to flapping fins. A detailed theoretical investigation has been carried out to predict the optimal operating parameters along with the fin stiffness to reduce the COM oscillations for a given self-propelled speed (SPS). Some design guidelines have been proposed which reduce COM oscillations that aid in the development of aerial and underwater robotic vehicles.
Structural Analysis of Morphing Airfoils for Camber Adaptive Wing
Authors: Feng Ning , Liu Liwu , Liu Yanju , Leng Jinsong
Published: January 2016

The chord-wise bending airfoil wing could be achieved by employing a kind of active morphing skin which was embedded with pneumatic muscle fibers. This camber morphing structure involves the discipline of structural mechanics which is analysed in this paper. Carbon fiber composite plate is utilized for the upper surface skin of the chord-wise bending airfoil structure, so the approach described in this paper starts from deformation analysis of the upper surface skin based on the classical laminate theory. Energy method was also used for solving the shape function of the upper surface skin which was under the condition of pure bending. While the active morphing skin was actuated at a series of discrete actuation pressures, the fixed geometrical shapes of the chord-wise bending airfoil structure could be obtained. Meanwhile the finite element method (FEM) was used for analyzing this chord-wise bending airfoil structure and the deformed shapes of the upper surface skins would be obtained. Deformed shapes of the upper surface skins between numerical analysis result and FEM analysis result were compared in this paper. This structural analysis work provides useful design and camber morphing characteristics for chord-wise bending airfoil structure. Developers of future shape-adaptive air vehicles have been provided with structural design tools.
How specific halide adsorption varies hydrophobic interactions
Authors: Stock Philipp , Müller Melanie , Utzig Thomas , Valtiner Markus
Published: January 2016

Hydrophobic interactions (HI) are driven by the water structure around hydrophobes in aqueous electrolytes. How water structures at hydrophobic interfaces and how this influences the HI was subject to numerous studies. However, the effect of specific ion adsorption on HI and hydrophobic interfaces remains largely unexplored or controversial. Here, the authors utilized atomic force microscopy force spectroscopy at well-defined nanoscopic hydrophobic interfaces to experimentally address how specific ion adsorption of halide ions as well as NH4+, Cs+, and Na+ cations alters interaction forces across hydrophobic interfaces. Our data demonstrate that iodide adsorption at hydrophobic interfaces profoundly varies the hydrophobic interaction potential. A long-range and strong hydration repulsion at distances D > 3 nm, is followed by an instability which could be explained by a subsequent rapid ejection of adsorbed iodides from approaching hydrophobic interfaces. In addition, the authors find only a weakly pronounced influence of bromide, and as expected no influence of chloride. Also, all tested cations do not have any significant influence on HI. Complementary, x-ray photoelectron spectroscopy and quartz-crystal-microbalance with dissipation monitoring showed a clear adsorption of large halide ions (Br−/I−) onto hydrophobic self-assembled monolayers (SAMs). Interestingly, iodide can even lead to a full disintegration of SAMs due to specific and strong interactions of iodide with gold. Our data suggest that hydrophobic surfaces are not intrinsically charged negatively by hydroxide adsorption, as it was generally believed. Hydrophobic surfaces rather interact strongly with negatively charged large halide ions, leading to a surface charging and significant variation of interaction forces.
Individual lipid encapsulated microbubble radial oscillations: Effects of fluid viscosity
Authors: Helfield Brandon , Chen Xucai , Qin Bin , Villanueva Flordeliza S.
Published: January 2016

Ultrasound-stimulated microbubble dynamics have been shown to be dependent on intrinsic bubble properties, including size and shell characteristics. The effect of the surrounding environment on microbubble response, however, has been less investigated. In particular, microbubble optimization studies are generally conducted in water/saline, characterized by a 1 cP viscosity, for application in the vasculature (i.e., 4 cP). In this study, ultra-high speed microscopy was employed to investigate fluid viscosity effects on phospholipid encapsulated microbubble oscillations at 1 MHz, using a single, eight-cycle pulse at peak negative pressures of 100 and 250 kPa. Microbubble oscillations were shown to be affected by fluid viscosity in a size- and pressure-dependent manner. In general, the oscillation amplitudes exhibited by microbubbles between 3 and 6 μm in 1 cP fluid were larger than in 4 cP fluid, reaching a maximum of 1.7-fold at 100 kPa for microbubbles 3.8 μm in diameter and 1.35-fold at 250 kPa for microbubbles 4.8 μm in diameter. Simulation results were in broad agreement at 250 kPa, however generally underestimated the effect of fluid viscosity at 100 kPa. This is the first experimental demonstration documenting the effects of surrounding fluid viscosity on microbubble oscillations, resulting in behavior not entirely predicted by current microbubble models.
Effects of Physical-Exercise-Based Rehabilitation Programs on the Quality of Life of Patients With Parkinson’s Disease: A Systematic Review of Randomized Controlled Trials
Authors: da Silva Franciele Cascaes , da Rosa Iop Rodrigo , dos Santos Patrícia Domingos , de Melo Lídia Mara Aguiar Bezerra , Filho Paulo José Barbosa Gutierres , da Silva Rudney
Published: January 2016

This study aimed to determine the effects of physical-exercise-based rehabilitation programs on quality of life of patients with Parkinson’s disease through a systematic review of randomized clinical trials. For this purpose the following electronic databases were selected: Medline by PubMed, Cochrane, Web of Science, and PEDro. The search strategy included the proposed descriptors in the Medical Subject Headings (MeSH), associated with a sensitive list of terms to search for randomized controlled trials (RCTs), without year and language restrictions. Fourteen studies were potentially relevant, and these studies were included. Physical-exercise-based rehabilitation programs realized 2–4 times a week, 60 min each session, for 6–12 weeks, and follow-up of 3 months promotes significant positive effects on quality of life in Parkinson’s disease patients at mild to moderate stages and disease duration around 6 years.
Social contacts, vaccination decisions and influenza in Japan
Authors: Ibuka Yoko , Ohkusa Yasushi , Sugawara Tamie , Chapman Gretchen B , Yamin Dan , Atkins Katherine E , Taniguchi Kiyosu , Okabe Nobuhiko , Galvani Alison P
Published: January 2016

Background

Contact patterns and vaccination decisions are fundamental to transmission dynamics of infectious diseases. We report on age-specific contact patterns in Japan and their effect on influenza vaccination behaviour.

Methods

Japanese adults (N=3146) were surveyed in Spring 2011 to assess the number of their social contacts within a 24 h period, defined as face-to-face conversations within 2 m, and gain insight into their influenza-related behaviour. We analysed the duration and location of contacts according to age. Additionally, we analysed the probability of vaccination and influenza infection in relation to the number of contacts controlling for individual's characteristics.

Results

The mean and median reported numbers of daily contacts were 15.3 and 12.0, respectively. School-aged children and young adults reported the greatest number of daily contacts, and individuals had the most contacts with those in the same age group. The age-specific contact patterns were different between men and women, and differed between weekdays and weekends. Children had fewer contacts between the same age groups during weekends than during weekdays, due to reduced contacts at school. The probability of vaccination increased with the number of contacts, controlling for age and household size. Influenza infection among unvaccinated individuals was higher than for those vaccinated, and increased with the number of contacts.

Conclusions

Contact patterns in Japan are age and gender specific. These contact patterns, as well as their interplay with vaccination decisions and infection risks, can help inform the parameterisation of mathematical models of disease transmission and the design of public health policies, to control disease transmission.
Tracking of physical activity and fitness during the early years
Authors: Caldwell Hilary A.T. , Proudfoot Nicole A. , King-Dowling Sara , Di Cristofaro Natascja A. , Cairney John , Timmons Brian W.
Published: January 2016

The early years are characterized by rapid physical growth and the development of behaviours such as physical activity. The objectives of this study were to assess the 12-month changes in and the tracking of physical activity and fitness in 400 preschoolers (201 boys, 4.5 ± 0.9 years of age). Physical activity data, expressed as minutes per day and as the percentage of time spent at various intensities while wearing an accelerometer, were collected in 3-s epochs for 7 days. Short-term muscle power, assessed with a 10-s modified Wingate Anaerobic Test, was expressed as absolute (W) and relative (W/kg) peak power (PP) and mean power (MP). Aerobic fitness, assessed with the Bruce Protocol progressive treadmill test, was expressed as maximal treadmill time and heart rate recovery (HRR). Light physical activity decreased by 3.2 min/day (p < 0.05), whereas vigorous physical activity increased by 3.7 min/day (p < 0.001), from year 1 to year 2. Physical activity exhibited moderate tracking on the basis of Spearman correlations (r = 0.45–0.59, p < 0.001) and fair tracking on the basis of κ statistics (κ = 0.26–0.38). PP and MP increased from year 1 (PP, 94.1 ± 37.3 W; MP, 84.1 ± 30.9 W) to year 2 (PP, 125.6 ± 36.2 W; MP, 112.3 ± 32.2 W) (p < 0.001) and tracked moderately to substantially (PP, r = 0.89, κ = 0.61; MP, r = 0.86, κ = 0.56). Time to exhaustion on the treadmill increased from 9.4 ± 2.3 min to 11.8 ± 2.3 min (p < 0.001) and tracked strongly (r = 0.82, κ = 0.56). HRR was unchanged at 65 ± 14 beats/min (p = 0.297) and tracked fairly (r = 0.52, κ = 0.23). The findings indicate that fitness tracks better than physical activity over a 12-month period during the early years.
Long-term aspen dynamics, trophic cascades, and climate in northern Yellowstone National Park
Authors: Beschta Robert L. , Painter Luke E. , Levi Taal , Ripple William J.
Published: January 2016

We report long-term patterns of quaking aspen (Populus tremuloides Michx.) recruitment for five ungulate exclosures in the northern ungulate winter range of Yellowstone National Park. Aspen recruitment was low (<3 aspen·ha−1·year−1) in the mid-1900s prior to exclosure construction due to herbivory by Rocky Mountain elk (Cervus elaphus Linnaeus, 1758) but increased more than 60-fold within 25 years after exclosure construction despite a drying climatic trend since 1940. Results support the hypothesis that long-term aspen decline in Yellowstone’s northern range during the latter half of the 20th century was caused by high levels of ungulate herbivory and not a drying climate. Gray wolves (Canis lupus Linnaeus, 1758) were reintroduced during 1995–1996. For the period 1995–2012, we summarized annual predator–prey ratios, ungulate biomass, and drought severity. The average density of young aspen increased from 4350 aspen·ha−1 in 1997–1998 to 8960 aspen·ha−1 in 2012; during the same time period, those >1 m in height increased over 30-fold (from 105 to 3194 aspen·ha−1). Increased heights of young aspen occurred primarily from 2007 to 2012, a period with relatively high predator–prey ratios, declining elk numbers, and decreasing browsing rates. Consistent with a re-established trophic cascade, aspen stands in Yellowstone’s northern range have increasingly begun to recover.
Confidence Intervals for Performance Measures of M/M/1 Queue with Constant Retrial Policy
Authors: Efrosinin Dmitry , Winkler Anastasia , Martin Pinzger
Published: January 2016

We consider the problem of estimation and confidence interval construction of a Markovian controllable queueing system with unreliable server and constant retrial policy. For the fully observable system the standard parametric estimation technique is used. The arrived customer finding a free server either gets service immediately or joins a retrial queue. The customer at the head of the retrial queue is allowed to retry for service. When the server is busy, it is subject to breakdowns. In a failed state the server can be repaired with respect to the threshold policy: the repair starts when the number of customers in the system reaches a fixed threshold level. To obtain the estimates for the system parameters, performance measures and optimal threshold level we analyze the system in a stationary regime. The performance measures including average cost function for the given cost structure are presented in a closed matrix form.
Some three-point correlation functions in the η-deformed AdS5 × S5
Authors: Bozhilov Plamen
Published: January 2016

We compute some normalized structure constants in the [Formula: see text]-deformed [Formula: see text] in the framework of the semiclassical approach. This is done for the cases when the “heavy” string states are finite-size giant magnons carrying one angular momentum and for three different choices of the “light” state: primary scalar operators, dilaton operator with nonzero momentum, singlet scalar operators on higher string levels. Since the dual field theory is still unknown, the results obtained here must be considered as conjectures or as predictions from the string theory side.
11-Colored knot diagram with five colors
Authors: Nakamura T. , Nakanishi Y. , Satoh S.
Published: January 2016

We prove that any 11-colorable knot is presented by an 11-colored diagram where exactly five colors of eleven are assigned to the arcs. The number five is the minimum for all non-trivially 11-colored diagrams of the knot. We also prove a similar result for any 11-colorable ribbon 2-knot.
PERSPECTIVES ON INNOVATION MANAGEMENT OF ECUADORIAN COMPANIES — EMPIRICAL EVIDENCE
Authors: DIAZ-VILLAVICENCIO GUILLERMO JAVIER , DIDONET SIMONE , DODD ALEXANDER
Published: January 2016

This paper examines the relationship of 40 practices of innovation management lifted from Tidd et al. (2013, p. 634) in 477 Ecuadorian companies. The sample is from the period 2013–2014 and are divided into micro, small, medium and large enterprises. The management practices are divided a priori into 5 constructs (strategy, processes, organisation, relationships and learning). We then carry out a descriptive analysis, where the degree of the implementation of practices in the entirety of the businesses are stipulated. Later, we test a model with inferential analysis (multiple regression analysis) where the degrees of significance of the practices are determined within each construct and their relation to the size of the companies. The innovation management potential in the Ecuadorian business environment is also discussed. The results show, that companies are far from displaying constant management practices in innovation, as such, general recommendations for companies in the study are given.
Ultrasonic-Microwave Synergistic Synthesis of RGO–Bi2WO6 Photocatalyst with High Photoactivity for Basic Nitrogen Compounds in Light Oil
Authors: Chen Ying , Ji Shenglun , Qiao Tengfei , Miao Shuang , Zhao Yu
Published: January 2016

Graphene–Bi2WO6 composite photocatalyst with excellent photocatalytic properties were synthetized by ultrasonic-microwave synergistic method. The obtained samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier infrared (FT-IR) spectrum, specific surface area analyzer (BET) and UV-Vis diffuse reflectance spectra. The photocatalytic activities of as-prepared samples were evaluated by degradation of pyridine in light oil under visible light irradiation. The results show that graphene changed appearance structure of Bi2WO6, which prevented the Bi2WO6 nanosheets reunion arrangement, and increased specific surface area of the catalyst. It can also reduce the recombination probability of photogenerated carrier, so as to improve the photocatalytic activity of the composite catalyst. The optimal amount of graphene is 2%, with the denitrification rate as high as 89.28%, much higher than that of pure Bi2WO6.
Firm Risk-Taking and CEO Visibility
Authors: Liu Yixin , Zhang Yilei , Jiraporn Pornsit
Published: January 2016

This paper investigates the relationship between CEO visibility and corporate risk-taking. The empirical results show that more visible CEOs tend to take more risk. A one-standard-deviation shock in the CEOs media exposure results in a 6.53% rise in total risk. We further investigate the channels of risk-taking activities and find that more visible CEOs seek more R&D investments. The positive effect of CEO visibility on firm risk policies is clearly of concern to bondholders. Consistent with this view, we report that CEO visibility has a significant negative effect on firm credit ratings. Our results highlight the importance of CEO visibility on a crucial corporate outcome — the extent of corporate risk-taking.
Interdependency between mechanical parameters and afferent nerve discharge in hypertrophic intestine of rats
Authors: Yang Jian , Zhao Jingbo , Chen Pengmin , Nakaguchi Toshiya , Grundy David , Gregersen Hans
Published: January 2016

Partial intestinal obstruction causes smooth muscle hypertrophy, enteric neuronal plasticity, motility disorders, and biomechanical remodeling. In this study we characterized the stimulus-response function of afferent fibers innervating the partially obstructed jejunum. A key question is whether changes in afferent firing arise from remodeled mechanical tissue properties or from adaptive afferent processes. Partial obstruction was created by placing a polyethylene ring for 2 wk in jejunum of seven rats. Sham obstruction was made in six rats and seven rats served as normal controls. Firing from mesenteric afferent nerve bundles was recorded during mechanical ramp, relaxation, and creep tests. Stress-strain, spike rate increase ratio (SRIR), and firing rate in single units were assessed for evaluation of interdependency of the mechanical stimulations, histomorphometry data, and afferent nerve discharge. Partial intestinal obstruction resulted in hypertrophy and jejunal stiffening proximal to the obstruction site. Low SRIR at low strains during fast distension and at high stresses during slow distension was found in the obstructed rats. Single unit analysis showed increased proportion of mechanosensitive units but absent high-threshold (HT) units during slow stimulation, decreased number of HT units during fast stimulation, and shift from HT sensitivity towards low threshold sensitivity in the obstructed jejunum. Biomechanical remodeling and altered afferent response to mechanical stimulations were found in the obstructed jejunum. Afferents from obstructed jejunum preserved their function in encoding ongoing mechanical stimulation but showed changes in their responsiveness. The findings support that mechanical factors rather than adaption are important for afferent remodeling.
Influence of Acid Modification Multiwall Carbon Nanotube Counter Electrodes on the Glass and Flexible Dye-Sensitized Solar Cell Performance
Authors: Maiaugree Wasan , Pimanpang Samuk , Jarernboon Wirat , Amornkitbamrung Vittaya
Published: January 2016

Multiwall carbon nanotubes (MWCNTs) were modified by acids (H2SO4 : HNO3) for generating active groups on the nanotube surface. Unmodified- and modified-carbon nanotubes were coated on the conductive glass and conductive plastic substrates by a slurry paste method, and they were used as the counter electrodes (CEs) of dye-sensitized solar cells (DSSCs). Scanning electron microscopy reveals that carbon nanotubes are evenly deposited on the conductive glass. The efficiency of the glass based DSSCs of unmodified- and modified-carbon nanotubes and Pt CEs is ~4.73%, ~5.66%, and ~6.08%, respectively. The efficiency of the plastic based DSSCs of the unmodified- and modified-carbon nanotubes CEs is ~0.80% and ~2.11%, respectively. The voltammogram and electrochemical impedance spectroscopy results suggest that the superior performance of the modified-carbon nanotubes DSSCs is attributable to the high electrocatalytic activity and the low charge-transfer resistance of the modified-carbon nanotubes film over the unmodified-carbon nanotubes film.
Terrain Segmentation of Greece Using the Spatial and Seasonal Variation of Reference Crop Evapotranspiration
Authors: Aschonitis Vassilis , Miliaresis George , Demertzi Kleoniki , Papamichail Dimitris
Published: January 2016

The study presents a combination of techniques for integrated analysis of reference crop evapotranspiration (ETo) in GIS environment. The analysis is performed for Greece and includes the use of (a) ASCE-standardized Penman-Monteith method for the estimation of 50-year mean monthlyETo, (b) cross-correlation and principal components analysis for the analysis of the spatiotemporal variability ofETo, (c)K-means clustering for terrain segmentation to regions with similar temporal variability ofETo, and (d) general linear models for the description ofETobased on clusters attributes. Cross-correlation revealed a negative correlation ofETowith both elevation and latitude and a week positive correlation with longitude. The correlation betweenEToand elevation was maximized during the warm season, while the correlation with latitude was maximized during winter. The first two principal components accounted for the 97.9% of total variance of mean monthlyETo.K-means segmented Greece to 11 regions/clusters. The categorical factor of cluster number together with the parameters of elevation, latitude, and longitude described satisfactorily theETothrough general linear models verifying the robustness of the cluster analysis. This research effort can contribute to hydroclimatic studies and to environmental decision support in relation to water resources management in agriculture.
Synthesis and Anti-Inflammatory Activity of Some O-Propargylated-N-acetylpyrazole Derived from 1,3-Diarylpropenones
Authors: Dhingra Ashwani Kumar , Chopra Bhawna , Dass Rameshwar , Mittal Sanjeev K.
Published: January 2016

In search of novel effective potent therapeutic agents delivered by oral route for inflammation treatment, some novel O-propargylated-N-acetylpyrazole analogs (5a–j) were prepared by treating N-acetylpyrazole (4a–j) derived from 1,3-diarylpropenones (3a–j) with propargyl bromide. Claisen-Schmidt condensation of a series of substituted aryl ketones 1 and benzaldehydes 2 in glacial acetic acid afforded 1,3-diarylpropenones which on further treatment with hydrazine hydrate in acetic acid under reflux conditions afforded 1-acetyl-3,5-diaryl-4,5-dihydro(1H)pyrazoles (4a–j). The products were characterized by using spectroscopic techniques such as IR and NMR. In addition, the in vivo anti-inflammatory activity of the synthesized compounds was determined using the carrageenan-induced paw oedema method in rats.