bluuebunny/crossref_metadata_2025_split huggingface dataset:
Clinical Evidence on Hemodiafiltration: A Systematic Review and a Meta‐analysis
Authors: Mostovaya Ira M. , Blankestijn Peter J. , Bots Michiel L. , Covic Adrian , Davenport Andrew , Grooteman Muriel P.C. , Hegbrant Jörgen , Locatelli Francesco , Vanholder Raymond , Nubé Menso J. 
Published: February 2014

AbstractIn this review, a systematic literature search and meta‐analysis were performed to assess the effects of hemodiafiltration (HDF) on clinical outcome, as compared with hemodialysis (HD). Furthermore, the relation between the convection volume in HDF and clinical outcome was studied. The literature search identified six randomized controlled trials (RCTs). In a meta‐analysis of these RCTs, HDF treatment was related to a decreased risk of mortality (RR: 0.84; 95% CI 0.73–0.96) and cardiovascular death (RR: 0.73; 95% CI 0.57–0.92). Post hoc analyses of the three largest RCTs suggested an inverse relation between the magnitude of convection volume and mortality risk. The evidence presented in this analysis supports a wider acceptance of HDF.
Human IgG antibody response to Aedes aegypti Nterm‐34 kDa salivary peptide as an indicator to identify areas at high risk for dengue transmission: a retrospective study in urban settings of Vientiane city, Lao PDR
Authors: Ndille Emmanuel Elanga , Dubot‐Pérès Audrey , Doucoure Souleymane , Mouchet François , Cornelie Sylvie , Sidavong Bounpone , Fournet Florence , Remoue Franck 
Published: February 2014

AbstractObjectiveUsing human IgG antibody response to the Aedes Nterm‐34 kDa salivary peptide as an indicator of human exposure to Aedes bites in surveying exposed populations from areas at risk of dengue virus (DENV) transmission in urban settings of Vientiane city, Lao PDR.MethodsEnzyme‐linked immunosorbent assay tests were performed to measure the IgG response to Nterm‐34 kDa peptide in blood samples collected within a flavivirus seroprevalence survey carried out in 2006 including 3558 randomly selected individuals. The level of IgG response to the Nterm‐34 kDa peptide in individuals was analysed in relation to the level of urbanisation of the individual's residence, areas that presented significant differences in the prevalence of recent DENV infection.ResultsNo differences were observed in the anti‐Nterm‐34 kDa IgG level between DENV‐positive and DENV‐negative individuals. However, the level of specific IgG response was higher among individuals living in slightly urbanised neighbourhoods than among those in more highly urbanised areas (P < 0.0001). Interestingly, a similar pattern had already been observed concerning the prevalence of recent DENV infection in the same populations.ConclusionThe results of this retrospective study indicate that the evaluation of human IgG response to the Aedes Nterm‐34 kDa salivary peptide could be a useful indicator to identify places with risk of dengue virus transmission in urban endemic areas.
Dynamics of Phononic Materials and Structures: Historical Origins, Recent Progress, and Future Outlook
Authors: Hussein Mahmoud I. , Leamy Michael J. , Ruzzene Massimo 
Published: February 2014

AbstractThe study of phononic materials and structures is an emerging discipline that lies at the crossroads of vibration and acoustics engineering and condensed matter physics. Broadly speaking, a phononic medium is a material or structural system that usually exhibits some form of periodicity, which can be in the constituent material phases, or the internal geometry, or even the boundary conditions. As such, its overall dynamical characteristics are compactly described by a frequency band structure, in analogy to an electronic band diagram. With roots extended to early studies of periodic systems by Newton and Rayleigh, the field has grown to encompass engineering configurations ranging from trusses and ribbed shells to phononic crystals and metamaterials. While applied research in this area has been abundant in recent years, treatment from a fundamental mechanics perspective, and particularly from the standpoint of dynamical systems, is needed to advance the field in new directions. For example, techniques already developed for the incorporation of damping and nonlinearities have recently been applied to wave propagation in phononic materials and structures. Similarly, numerical and experimental approaches originally developed for the characterization of conventional materials and structures are now being employed toward better understanding and exploitation of phononic systems. This article starts with an overview of historical developments and follows with an in-depth literature and technical review of recent progress in the field with special consideration given to aspects pertaining to the fundamentals of dynamics, vibrations, and acoustics. Finally, an outlook is projected onto the future on the basis of the current trajectories of the field.
Photocurrent Response of Composite Perovskite Oxide Thin Films With Specific Semiconducting and Ferroelectric Properties
Authors: Shieh Jay , Chen Szu-Wei , Fang Chia-Yu 
Published: February 2014

The goal of this study is to investigate photocatalytic semiconductor systems which are layered thin film composites built from perovskite oxide materials with characteristics such as small and large band gaps and/or ferroelectricity. In order to improve the efficiency of photocatalysis, semiconductor heterojunctions within the developed composites have been designed to possess electronic band offsets favoring the separation of photo-induced electron and hole (e−/h+) pairs. Furthermore, the remanent polarization of the ferroelectric component within the composites has been utilized to induce favorable band bending at the material interface, lowering the potential barrier for electron transfer. The band offsets and ferroelectric polarization could be considered as built-in electric fields; how they interact with photo-induced e−/h+ would greatly affect the photocatalytic properties of the composites. In this study, various perovskite oxide thin film materials — large band gap strontium titanate (SrTiO3), small band gap silver niobate (AgNbO3) and ferroelectric lead lanthanum titanate (PLT) — were combined to form layered thin film composites. The composites were then adopted as photoanodes in a photoelectrochemical cell and detailed characterization of their photocurrent response was carried out under different light irradiation and ferroelectric polarization conditions. Electronic band offsets at the material interface (i.e., heterojunction) were determined by ultraviolet-visible spectrophotometry and ultraviolet photoelectron spectroscopy. Electric field poling of the ferroelectric component was achieved by non-contact corona charging.
Our results have shown that the band offsets at the SrTiO3-AgNbO3 heterojunction were about 1.0 eV in conduction band edge and 0.4 eV in valence band edge, promoting the rapid separation of photo-induced charge carriers; i.e., the flow of e− from SrTiO3 to AgNbO3 and the flow of h+ from AgNbO3 to SrTiO3. It was found that ferroelectric PLT could be used as a seeding layer for the low-temperature (500 °C) growth of SrTiO3/AgNbO3 thin film composites on ITO/glass substrates, forming a layered structure of SrTiO3/AgNbO3/PLT/ITO. In addition, the photocurrent density of the composites could be increased by depositing gold nanoparticles at the PLT-ITO interface. When the polarization of the PLT layer was poled toward the AgNbO3 layer, the potential barrier associated with the flow of e− to the ITO electrode was reduced by favorable band bending created at the AgNbO3-PLT interface. This resulted in a significant increase in photocurrent density.
Multi-Purpose Avionics Core Element: Using Digital Materials and Advanced Manufacturing to Rapidly Develop Cube Satellite Subsystems and Components
Authors: Hartney Christopher , Agasid Elwood , Hovsepian Sarah 
Published: February 2014

The NASA Ames Research Center (NASA Ames) Center Chief Technologist (CCT) Office sponsors the Advanced Digital Materials and Manufacturing for Space (ADMMS) Initiative, which focuses on advanced manufacturing technologies for space, including identifying several target products, areas and applications, approaches for advanced manufacturing, mechanisms for collaboration, and complementary facilities. The pilot project for this initiative is the Multi-Purpose Avionics Core Element (M-PACE). The primary goal of M-PACE is to demonstrate advanced manufacturing techniques, such as additive manufacturing and Digital Materials, to minimize the cost of cube satellites and increase their modularity. M-PACE will be designed and built at the NASA Ames’ SpaceShop, which is a state-of-the-art advanced manufacturing facility built for NASA researchers to formulate ideas for projects.
The final products of M-PACE are several completed side panels of a one-unit (1U) (10 cm cube) cube satellite prototype built using commercial off-the-shelf (COTS) components, which will show the basic functionality of the internal payload by connecting it to the side panels for power and other subsystem capabilities. Within the structure, we are investigating the use of Digital Materials, which are universal building materials with the ability to increase precision and ease of assembly and disassembly of three dimensional (3D) objects. M-PACE will use COTS power systems and open-source hardware and software to distribute data through Ethernet through the use of snap-fit card connectors. Similar to Peripheral Component Interconnect (PCI) Express cards, we envision the spacecraft subsystems and payloads to be on a PC104-like board that will slide into the side panel connectors to enable distribution of power and data. This design has the potential to greatly reduce the cost of Cube Satellite testing and integration due to the absence of wires and ease of access to internal boards for any necessary modifications.
Wave Rich Laser Ultrasonic Wavenumber Imaging for Laser Ultrasonic Propagation Imaging System With Air-Coupled Transducer
Authors: Sunuwar Nitam , Lee Jung-Ryul 
Published: February 2014

Interest in ultrasonic guided wave based Structural Health Monitoring and a nondestructive evaluation system has grown in recent years, especially to monitor thin plate like structures. However, an effective signal processing and imaging algorithms are essential to achieve necessary performance. This paper describes wave rich laser ultrasonic wavenumber imaging method (UWI) method for damage visualization. Ultrasonic waves were generated by a scanning laser source and acquired using a capacitance air coupled transducer (ACT). However, the inherent existence of multiple Lamb wave modes in signal makes it harder for effective damage evaluation. This is further complicated if the reflections from the boundaries are present in the signal. The use of an ACT with an in-line programmable filter helps to isolate lower order Lamb wave modes (Ao and So), since the dispersive waves radiate at certain angle from the specimen governed by Snell’s law. By comparing the results from the ultrasonic wavefield image obtained using the ACT and a PZT contact sensor under the same experimental condition, mode isolation phenomena was verified.
Such isolated wave mode was processed using a proposed wave rich UWI algorithm where a wave rich field was generated by superposing the wavefields. The mode filtered measurements were arranged in 3D space-time domain where each slice in time domain represents 2D wavefield image. A 2D Fast Fourier Transform (FFT) was applied to this spatial information in time domain which transformed it to a wavenumber domain. A wavenumber filter is then applied and inverse Fourier transformed to get back to the wavenumber filtered measurement. However, instead of applying filter to every 2D slice in time domain, certain frames were selected and merged to replicate wave propagation in total scan-area. This wave rich field not only saves time and space but also reduce computational complexity during post-processing. This method was tested successfully in an aluminum plate with milled area damage and a composite fiber-reinforced plastic (CFRP) wing skin with two impact damages.
Development of a SMA-Based, Slat-Cove Filler for Reduction of Aeroacoustic Noise Associated With Transport-Class Aircraft Wings
Authors: Turner Travis L. , Kidd Reggie T. , Hartl Darren J. , Scholten William D. 
Published: February 2014

Airframe noise is a significant part of the overall noise produced by typical, transport-class aircraft during the approach and landing phases of flight. Leading-edge slat noise is a prominent source of airframe noise. The concept of a slat-cove filler was proposed in previous work as an effective means of mitigating slat noise.
Bench-top models were developed at 75% scale to study the feasibility of producing a functioning slat-cove filler. Initial results from several concepts led to a more-focused effort investigating a deformable structure based upon pseudoelastic SMA materials. The structure stows in the cavity between the slat and main wing during cruise and deploys simultaneously with the slat to guide the aerodynamic flow suitably for low noise.
A qualitative parametric study of SMA-enabled, slat-cove filler designs was performed on the bench-top. Computational models were developed and analyses were performed to assess the displacement response under representative aerodynamic load. The bench-top and computational results provide significant insight into design trades and an optimal design.
Principles of Biomolecular Network Design
Authors: Freeman Eric C. , Philen Michael K. , Leo Donald J. 
Published: February 2014

Networks of biomolecular unit cells are proposed as a new type of biologically inspired intelligent materials. These materials are derived from natural cellular mechanics and aim to improve current biologically-inspired technologies by recreating the desired systems from the basic building block of the natural world; the cell. The individual biomolecular unit cell is able to replicate natural cellular abilities through a combination of lipid bilayer membranes containing embedded proteins and peptides. While individual unit cells offer an ideal testing environment for demonstrating proofs of concept, more advanced abilities require larger networks, utilizing cell-to-cell interactions.
The cell-to-cell interactions often involve multiple modes of communication, which have been identified for this paper as primarily electrical, chemical, and mechanical phenomenon. Previous modeling efforts have incorporated the electrical portion through equivalent circuit models, but these lack the ability to fully explain some of the network characteristics. A new formulation is presented here to illustrate how these three classes of phenomenon may be coupled to achieve various engineering design goals.
An Adaptive Tuned Mass Damper Using Friction Bars
Authors: Neubauer Marcus , Wallaschek Jörg 
Published: February 2014

This publication presents a novel realization of a Tuned Mass Damper (TMD) using friction bars. Because of the friction forces in the contact, they dissipate energy similar to a dry friction contact. Because of the nonlinear, amplitude depending damping behavior, it is possible to have the pure absorbing effect combined with broadband damping, which cannot be achieved by the classical, viscousely damped TMD.
Special focus is layed on the modeling aspects. The friction contact is modeled using the Harmonic Balance method, and with help of the replacement parameters the system behavior is studied.
Three-Dimensional Numerical Simulation of Thermomechanical Constitutive Model for Shape Memory Polymers With Application to Morphing Wing Skin
Authors: Balogun Olaniyi A. , Mo Changki , Mazher A. K. , Brigham John C. 
Published: February 2014

This paper presents three-dimensional numerical simulation of thermomechanical constitutive model for shape memory polymers. Shape memory polymers (SMPs) are a class of smart materials with high potential for application to automotive, aerostructures, and medical devices, which can benefit from its intrinsic shape changing properties. In particular, looking at its application to aerospace substructure such as morphing wings, thermomechanical behavior of the SMPs needs to be well established and predicted.
In order to predict the thermomechanical behavior of SMPs structures, a one-dimensional rheological thermomechanical constitutive model was adopted and a numerical simulation of this model was developed using a commercial finite element analysis package ABAQUS. The particular one-dimensional model was selected due to its potential to represent the key material behaviors of SMP with a relatively low number of required material constants, which is practical for engineering industrial applications. The model was expanded to a three-dimensional isotropic model and then incorporated into the finite element method by means of an ABAQUS user-defined subroutine (UMAT). The methods of three-dimensional expansion and numerical implementation are presented in this work. A time evolution of the analysis was conducted by making use of the backward difference method, which was applied to all quantities within the model including the material properties. A comparison of the numerical simulation results was carried out with the available experimental data.
Numerical simulation results clearly exhibit the thermomechanical properties of the material, which include shape fixity, shape recovery, and recovery stress. Finally, a preliminary set of predictions for an unmanned aerial vehicle (UAV) morphing wing skin are also presented.
Cooling Efficiencies of a NiTi-Based Cooling Process
Authors: Schmidt Marvin , Schütze Andreas , Seelecke Stefan 
Published: February 2014

Energy saving and environmental protection are topics of growing interest. In the light of these aspects alternative refrigeration principles become increasingly important. Shape memory alloys (SMA), especially NiTi alloys, generate a large amount of latent heat during solid state phase transformations, which can lead to a significant cooling effect in the material. These materials do not only provide the potential for an energy-efficient cooling process, they also minimize the impact on the environment by reducing the need for conventional ozone-depleting refrigerants.
Our paper, presenting first results obtained in a project within the DFG Priority Program SPP 1599 “Ferroic Cooling”, focuses on the thermodynamic analysis of a NiTi-based cooling system. We first introduce a suitable cooling process and subsequently illustrate the underlying mechanisms of the process in comparison with the conventional compression refrigeration system. We further introduce a graphical solution to calculate the energy efficiency ratio of the system. This thermodynamic analysis method shows the necessary work input and the heat absorption of the SMA in stress/strain- or temperature/entropy-diagrams, respectively. The results of the calculations underline the high potential of this solid-state cooling methodology.
On the Control of a Dielectric Elastomer Artificial Muscle With Variable Impedance
Authors: Palli Gianluca , Berselli Giovanni 
Published: February 2014

Artificial Muscles based on Dielectric Elastomers (DE) can potentially enable the realization of bio-inspired actuation systems whose intrinsic compliance and damping can be varied according to the task requirements. Nonetheless, the control of DE-based Variable Impedance Actuators (VIA) is not trivial owing to the non-linear viscoelastic response which characterizes the acrylic dielectrics commonly employed in practical devices.
In this context, the purpose of the present paper is to outline a novel strategy for the control of DE-based VIA. Although the proposed methodology is applicable to generic DE morphologies, the considered system is composed of a couple of conically-shaped DE films in agonistic-antagonistic configuration. Following previously published results, the system dynamic model is firstly recalled. Then, a DE viscoelasticity compensation technique is outlined together with a control law able to shape the DE actuator impedance as desired. The operative limits of the system are explicitly considered and managed in the controller by increasing the operating DE actuator stiffness if required. In addition, the problem of model uncertainties compensation is also addressed. Finally, as a preliminary step towards the realization of a practical DE-based VIA, the proposed control approach is validated by means of simulations.
Blade Tip Carving Effects on the Aero-Thermal Performance of a Transonic Turbine
Authors: De Maesschalck C. , Lavagnoli S. , Paniagua G. 
Published: February 2014

Tip leakage flows in unshrouded high speed turbines cause large aerodynamic penalties, induce significant thermal loads and give rise to intense thermal stresses onto the blade tip and casing endwalls. In the pursuit of superior engine reliability and efficiency, the turbine blade tip design is of paramount importance and still poses an exceptional challenge to turbine designers. The ever-increasing rotational speeds and pressure loadings tend to accelerate the tip flow velocities beyond the transonic regime. Overtip supersonic flows are characterized by complex flow patterns, which determine the heat transfer signature. Hence, the physics of the overtip flow structures and the influence of the geometrical parameters on the overtip flow require further understanding to develop innovative tip designs. Conventional blade tip shapes are not adequate for such high speed flows and hence, potential for enhanced performances lays in appropriate tip shaping.
The present research aims to quantify the prospective gain offered by a fully contoured blade tip shape against conventional geometries such as a flat and squealer tip. A detailed numerical study was conducted on a modern transonic turbine rotor blade (Reynolds number is 5.5 × 105, relative exit Mach number is 0.9) by means of three-dimensional Reynolds-Averaged Navier-Stokes calculations. The novel contoured tip geometry was designed based on a 2D tip shape optimization in which only the upper 2% of the blade span was modified. This study yields a deeper insight into the application of blade tip carving in high speed turbines and provides guidelines for future tip designs with enhanced aerothermal performances.
Effects of Blade Degradation on Turbine Performance
Authors: Granovskiy Andrey , Manaev Igor , Vassiliev Vladimir , Kissel Harald 
Published: February 2014

The degradation of gas turbine parts due to aging leads to changes in airfoil shape and often causes performance loss. Although the degradation mechanisms and their effects on performance are understood in general (e.g. it is well known that fouling of compressor airfoils reduces mass flow and efficiency), the first quantitative relationships between specific types of part degradation and performance characteristics have only recently been published.
In this paper the degradation of turbine blades with aft-loaded airfoils is considered. The typical deviations of shape were identified based on field experience. The effects of these deviations on turbine performance were assessed using different calculation methods, including 3D Navier-Stokes calculations and methods based on empirical correlations. The effect of blades-length reduction, chord-length reduction, changes in trailing-edge thickness and shape, and variation of stagger angle were analysed. The analysis showed that for aft-loaded airfoils without shrouds, the major influence on turbine performance is the degradation of radial clearances.
A simplified engineering procedure allowing estimation of turbine performance loss due to degradation has been developed. This paper demonstrates how this simplified procedure, can be applied to the estimation of turbine recovery potential during a typical engine overhaul.