bluuebunny/crossref_metadata_2025_split huggingface dataset:
Identification, Coding, and Reimbursement of Pediatric Malnutrition at an Urban Academic Medical Center
Authors: Bierman Sabrina M. , Peterson Sarah J. , Chen Yimin 
Published: March 2018

AbstractBackgroundThe American Academy of Nutrition and Dietetics and the American Society of Parenteral and Enteral Nutrition released a pediatric malnutrition consensus statement in 2014 recommending the use of z‐scores as indicators for identification and documentation of malnutrition. A shift in focus is needed on standardizing pediatric malnutrition language at institutions nationwide to make study data comparable. With this standardized language, establishment of institutional baselines for identification, coding, and reimbursement of pediatric malnutrition is crucial to measure process improvements.ObjectivesThe objectives of this study were to determine the prevalence of malnutrition among pediatric patients at an urban academic medical center, the frequency of malnutrition codes used, and the reimbursement impact of coding for malnutrition.MethodsElectronic medical records of pediatric patients admitted from January 2013 to December 2015 were reviewed. Malnutrition was identified based on registered dietitian identification and z‐score. Patients given a malnutrition‐related International Classification of Diseases code upon discharge were identified. A reimbursement calculation was performed: the malnutrition‐related International Classification of Diseases code was removed to determine the difference in reimbursement with vs without the code. Results: Of the 1,532 admissions included in this study, 464 (30%) were identified as malnourished. A total of 152 (33%) malnourished patients were given a malnutrition‐related secondary diagnosis. The calculation revealed that coding for malnutrition resulted in an additional $27,665.70 to the medical center.ConclusionMalnutrition coding may have a significant financial impact and processes improvement efforts can be made to improve malnutrition coding.
Venovenous Extracorporeal Membrane Oxygenation in an Adult Patient With Prader‐Willi Syndrome: A Nutrition Case Report
Authors: Pelekhaty Stacy , Menaker Jay 
Published: March 2018

AbstractPrader‐Willi Syndrome (PWS) is a genetic condition that results in a constellation of symptoms and typically results in hyperphagia and obesity in adulthood. Critically ill adults with PWS present a unique challenge to the nutrition professional, particularly when they require support modalities such as extracorporeal membrane oxygenation (ECMO). The purpose of this case study is to review the nutrition care of a critically ill adult patient with PWS who required venovenous ECMO. The patient was successfully managed with a hypocaloric, high‐protein approach, which did not result in the diagnosis of malnutrition during his hospitalization. The patient was ultimately transitioned off extracorporeal life support and discharged to a rehabilitation facility.
Spectrum mobility management in cognitive two‐tier networks
Authors: Sethom Kaouthar , Pujolle Guy 
Published: March 2018

SummaryRecently, new type of small Base Station known as “femtocell” has emerged. Femtocells are deployed by customers with minimal or no radio frequency planning in arbitrary locations. Thus, operators must use new approaches rather than the classic network planning and optimization. Self‐organization techniques will allow femtocells to integrate themselves into the network, learn about their environment, and adjust their parameters (power, frequency) accordingly. In this paper, a new spectrum mobility management algorithm is proposed. It allows intelligent use of the spectrum by secondary user (femtocell guest user) accessing spectrum holes unoccupied by primary users (subscriber user) and handing over to new channels or femtocells when primary user appears. Our solution aims to have more adaptive and aware communication system, which can make better use of available natural resources.
Exploring basal sliding with a fluidity‐based, ice‐sheet model using FOSLS
Authors: Allen Jeffery , Manteuffel Tom , Rajaram Harihar 
Published: March 2018

SummaryThis paper develops two first‐order system—in this context, first‐order refers to the order of the PDE not to the model—least‐squares, fluidity‐based formulations of a nonlinear Stokes flow model for ice sheets that attempt to overcome the difficulties introduced by unbounded viscosity. One commonly used way to define viscosity, Glen's law, allows viscosity to become unbounded as the strain rates approach zero. Often, numerical approaches overcome these singularities by modifying viscosity to limit its maximum. The formulations in this paper, however, reframe the problem to avoid viscosity altogether by defining the system in terms of the inverse of viscosity, which is known as fluidity. This results in a quantity that approaches zero as viscosity approaches infinity. Additionally, a set of equations that represent the curl of the velocity gradient is added to help approximate the solution in a space closer to H1, which improves algebraic multigrid convergence. Previous research revealed that the first‐order system least‐squares formulation has difficulties in maintaining optimal discretization convergence on more complex domains. This paper discovers that this problem is linked to how the curl equations are scaled and that stronger scalings result in better solver performance but worse discretization convergence. Determining if there is an optimal scaling that balances performance and convergence is still an open question. Additionally, the fluidity‐based formulations are tested with three 2D benchmark problems. Two of these benchmark problems involve basal sliding and one involves a time‐dependent free surface. The fluidity‐based solutions are consistent with the standard Galerkin method using Taylor–hood elements while better resolving viscosity.
Regularization matrices for discrete ill‐posed problems in several space dimensions
Authors: Dykes Laura , Huang Guangxin , Noschese Silvia , Reichel Lothar 
Published: March 2018

SummaryMany applications in science and engineering require the solution of large linear discrete ill‐posed problems that are obtained by the discretization of a Fredholm integral equation of the first kind in several space dimensions. The matrix that defines these problems is very ill conditioned and generally numerically singular, and the right‐hand side, which represents measured data, is typically contaminated by measurement error. Straightforward solution of these problems is generally not meaningful due to severe error propagation. Tikhonov regularization seeks to alleviate this difficulty by replacing the given linear discrete ill‐posed problem by a penalized least‐squares problem, whose solution is less sensitive to the error in the right‐hand side and to roundoff errors introduced during the computations. This paper discusses the construction of penalty terms that are determined by solving a matrix nearness problem. These penalty terms allow partial transformation to standard form of Tikhonov regularization problems that stem from the discretization of integral equations on a cube in several space dimensions.
A posteriori error estimate for computing tr(f(A)) by using the Lanczos method
Authors: Chen Jie , Saad Yousef 
Published: March 2018

SummaryAn outstanding problem when computing a function of a matrix,f(A), by using a Krylov method is to accurately estimate errors when convergence is slow. Apart from the case of the exponential function that has been extensively studied in the past, there are no well‐established solutions to the problem. Often, the quantity of interest in applications is not the matrixf(A) itself but rather the matrix–vector products or bilinear forms. When the computation related tof(A) is a building block of a larger problem (e.g., approximately computing its trace), a consequence of the lack of reliable error estimates is that the accuracy of the computed result is unknown. In this paper, we consider the problem of computing tr(f(A)) for a symmetric positive‐definite matrixAby using the Lanczos method and make two contributions: (a) an error estimate for the bilinear form associated withf(A) and (b) an error estimate for the trace off(A). We demonstrate the practical usefulness of these estimates for large matrices and, in particular, show that the trace error estimate is indicative of the number of accurate digits. As an application, we compute the log determinant of a covariance matrix in Gaussian process analysis and underline the importance of error tolerance as a stopping criterion as a means of bounding the number of Lanczos steps to achieve a desired accuracy.
Applying functional principal components to structural topology optimization
Authors: Alaimo Gianluca , Auricchio Ferdinando , Bianchini Ilaria , Lanzarone Ettore 
Published: March 2018

SummaryStructural topology optimization aims to enhance the mechanical performance of a structure while satisfying some functional constraints. Nearly all approaches proposed in the literature are iterative, and the optimal solution is found by repeatedly solving a finite element analysis (FEA). It is thus clear that the bottleneck is the high computational effort, as these approaches require solving the FEA a large number of times. In this work, we address the need for reducing the computational time by proposing a reduced basis method that relies on functional principal component analysis (FPCA). The methodology has been validated considering a simulated annealing approach for compliance minimization in 2 classical variable thickness problems. Results show the capability of FPCA to provide good results while reducing the computational times, ie, the computational time for an FEA is about one order of magnitude lower in the reduced FPCA space.
Comparison of PID and FOPID controllers tuned by PSO and ABC algorithms for unstable and integrating systems with time delay
Authors: Bingul Zafer , Karahan Oguzhan 
Published: March 2018

SummaryThis paper deals with optimization and design of an integer order–based and fractional order–based proportional integral derivative (PID) controller tuned by particle swarm optimization (PSO) and artificial bee colony (ABC) algorithms. These algorithms were used to find the best parameters for the best controller performance. A comparative study has been made to highlight the advantage of using ABC‐based controller over a PSO‐based controller. The validity of the controller tuning algorithms was tested in 2 different systems with time delay and a nonminimum phase zero used commonly in process control. The optimal tuning process of the PID and fractional order PID controllers has also been performed with 3 different cost functions. From the perspectives of time‐domain performance criteria, such as settling time, rise time, overshoot, and steady‐state error, the controller tuned by ABC gives better dynamic performances than controllers tuned by the PSO. Moreover, the results obtained from robustness analysis showed that the parameters of controller tuned by ABC are quite robust under internal and external disturbances.
Macromolecular Crowding May Significantly Affect the Performance of an MRI Contrast Agent: A 1H NMR Spectroscopy, Microimaging, and Fast‐Field‐Cycling NMR Relaxometry Study
Authors: Cheng Ren‐Hao , Chen Jie‐Min , Chen Yu‐Wen , Cai Honghao , Cui Xiaohong , Hwang Dennis W. , Chen Zhong , Ding Shangwu 
Published: March 2018

AbstractContrast enhancement agents are often employed in magnetic resonance imaging (MRI) for clinical diagnosis and biomedical research. However, the current theory on MRI contrast generation does not consider the ubiquitous presence of macromolecular crowders in biological systems, which poses the risk of inaccurate data interpretation and misdiagnosis. To address this issue, herein the macromolecular crowding effects on MRI contrast agent are investigated with the 1H relaxation rate of water in aqueous solutions of Dotarem with different concentrations of macromolecules. Two representative macromolecular crowder systems are used: polyethylene glycol (with no specific secondary structure) and bovine serum albumin (with compact secondary and tertiary structures). The water 1H relaxation rates in various solutions are measured in a fixed magnetic field and in variable magnetic fields. The results show significant crowding effects for both crowders. The relaxation rate is proportional to the concentration of the MRI contrast agent but shows conspicuous superlinearity with respect to the concentration of the crowder. The size of polyethylene glycol does not affect the relaxivity of water in Dotarem solutions. The above effects are verified with T1‐ and T2‐weighted NMR microimages. These results highlight the importance of the effect of macromolecular crowding on the MRI contrast agent and are valuable for understanding the mechanism of MRI contrast agents and designing new‐generation MRI contrast agents.
Field‐induced plasticity of magneto‐sensitive elastomers in context with soft robotic gripper applications
Authors: Chavez Vega Jhohan , Kaufhold Tobias , Böhm Valter , Becker Tatiana , Zimmermann Klaus , Martens Michael , Schilling Meinhard , Gundermann Thomas , Odenbach Stefan 
Published: March 2018

AbstractMagnetic hybrid composite materials have the peculiarity to change their mechanical properties when influenced by a magnetic field. This special characteristic can be used to develop smart actuators, sensor systems and control mechanisms. In the paper the use of magneto‐sensitive elastomers (MSE), composed of silicone rubber and silicone oil, with incorporated magnetic particles, in a form‐fit gripper application is considered. The field‐induced plasticity effect of MSE is used, to realise reversible recoverable shape adaptation of the gripper to the objects to be manipulated. The focus lies on the characterisation of the mechanical properties of the MSE for the specific application. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Model Order Reduction for Parametric Non‐linear Mechanical Systems: State of the Art and Future Research
Authors: Meyer Christian H. , Lerch Christopher , Lohmann Boris , Rixen Daniel J. 
Published: March 2018

AbstractOne research objective in the Priority Program 1897 “Calm, Smooth and Smart” of the German Research Foundation (DFG – SPP 1897) is the development of model order reduction techniques for parametric non‐linear mechanical systems to enable efficient design, simulation, analysis, optimization and control of those. As a starting point for our research, this contribution provides an overview of the main challenges and well‐established reduction techniques in this research area, at that stage, neglecting parameter dependencies. This includes simulation‐based as well as simulation‐free reduction bases generation and hyperreduction of the non‐linear force terms. An extension of the Krylov directions in moment matching based on the concept of modal derivatives is also sketched. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Polymorphic Uncertainty Modeling of Heterogeneous Thermo‐Hydro‐Mechanical Coupled Systems under Vague Assumptions on Parameter Correlations
Authors: Schmidt Albrecht , Nguyen‐Tuan Long , Könke Carsten , Lahmer Tom 
Published: March 2018

AbstractHeterogeneous material properties can be found in new hybrid materials as well as in existing engineering constructions, e.g. dams. The material properties can be modeled by correlated random fields, taking into account their possible interdependencies. The vaguely known random field parameters like correlation coefficient and correlation length are described by fuzzy sets. Applying those fields in a reliability analysis result in failure probability fuzzy sets that can be interpreted by the engineer. This proposed methodology is applied to a simple illustrative one‐dimensional model to show the principle procedure. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A Monolithic Solution Scheme for a Phase Field Model of Ductile Fracture
Authors: Noll Timo , Kuhn Charlotte , Müller Ralf 
Published: March 2018

AbstractA phase field model for elastic‐plastic fracture is presented, which is based on an energy functional composed of an elastic energy contribution, a plastic dissipation potential and a fracture energy. The coupling of the mechanical fields with the fracture field is modeled by a degradation function. Due to the proposed coupling it is possible to solve the global system of differential equations in a monolithic iterative solution scheme. Numerical simulations are presented, where the choice of the degradation function is investigated and a staggered is compared to monolithic iteration scheme. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Phase‐Field Models for the Failure of Anisotropic Continua
Authors: Dal Hüsnü , Gültekin Osman , Aksu Denli Funda , Holzapfel Gerhard A. 
Published: March 2018

AbstractThis study presents a phase‐field approach for an anisotropic continuum to model fracture of biological tissues and fiber‐reinforced composites. We start with the continuous formulation of the variational principle for the multi‐field problem manifested through the deformation map and the crack phase‐field at finite strains which leads to the Euler–Lagrange equations of the coupled problem. In particular, the coupled balance equations derived render the evolution of the anisotropic crack phase‐field and the balance of linear momentum. In addition, we propose a novel energy‐based anisotropic failure criterion which regulates the evolution of the crack phase‐field. The coupled problem is solved using a one‐pass operator‐splitting algorithm composed of a mechanical predictor step and a crack evolution step. Representative numerical examples are devised for crack initiation and propagation in carbon‐fiber‐reinforced polymerg composites. Model parameters are obtained by fitting the set of novel experimental data to the predicted model response; the finite element results qualitatively capture the effect of anisotropy in stiffness and strength. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Variational interface zone model for modeling of fluid induced fracture propagation
Authors: Khisamitov Ildar , Meschke Günther 
Published: March 2018

AbstractA novel variational framework for an interface zone model is developed and extended to poroelasticity. As was previously promoted in [1,2], the total energy of the system is composed by the bulk potential and fracture surface energy. In contrast to the phase‐field method, the fracture surface is approximated directly along the edges of the finite elements in terms of interface zero‐thickness finite elements. By introducing a new degree of freedom c (damage field) on the interface level, the solution is found by the minimization of the total potential energy with respect to the displacements and the damage field. An elastic interface constitutive law allowing for a normal and tangential displacement opening is adopted in the pre‐fracture regime. Assuming, that a crack propagates according to the Griffith's criterion of brittle fracture, fracture initiates and propagates in normal opening mode. Biot's theory is applied both to the bulk and interface elements for the simulation of fluid driven fracture in fully saturated materials. The pressure field within the interfaces is averaged between the pressure at the bulk element faces. Pressure continuity is enforced by means of a penalty functional. The flow within the fracture is modeled by the cubic law taking the displacement and damage variables into account. A number of numerical benchmark tests, which include comparisons with experimental results and analytical solutions, are performed to demonstrate the performance of the model. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Modelling of the gelation process of biopolymers using the phase‐field method
Authors: Zhou Bei , Heider Yousef , Markert Bernd 
Published: March 2018

AbstractBiopolymer gels have many applications in tissue engineering. In recent years, biopolymer gels are widely used as scaffold material in the 3D bioprinting technique for tissues and organs. To optimise the printing process, it is important to study and understand the temperature‐ and time‐dependent gelation kinetics of biopolymer gels.In this study, a thermodynamic model is proposed to describe the gelation kinetics of thermoreversible gels, which are driven by the coil‐to‐helix transition. In this model, the gelation process is assumed to proceed in two steps. The process starts from the reference state, in which the solution consists of solvent molecules and polymer chains with n segments in random coil configuration. Polymer chains firstly change from the random coil state to the partially helical state, followed by the aggregation of helical parts of polymer chains. This formation and the followed aggregation of helices lead to the eventual polymer network. With the help of the phase‐field method, numerical simulations of a spatial and time varied gelation process of droplets in 3D bioprinting are performed using the finite element method (FEM). (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Drag reduction of spanwise transversal traveling surface waves with stepwise amplitude increase
Authors: Meysonnat Pascal S. , Albers Marian , Schröder Wolfgang 
Published: March 2018

AbstractThe effect of sudden amplitude changes of a spanwise traveling surface wave on turbulent boundary layers is investigated numerically using high resolution large‐eddy simulation (LES). The results show drag reduction of up to 9 percent and an adaptation of the turbulent flow to the changed input parameter within 100 convective times. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Building blocks for a leading edge high‐order flow solver
Authors: Huismann Immo , Stiller Jörg , Fröhlich Jochen 
Published: March 2018

AbstractAn important trend in Computational Fluid Dynamics is towards high‐order methods, as they offer a substantially lower discretization error for the same number of degrees of freedom (DOF). Examples are the Spectral‐Element Methods (SEM) and Discontinuous Galerkin (DG) methods. Unfortunately, with most implementations the work load of such solvers increases drastically with the number of DOF, for example, when increasing the polynomial degree of the approximation. This issue gets particular pressing for elliptic solvers which are a vital building block in the time‐stepping of the incompressible Navier‐Stokes equations, resulting from pressure projection methods or implicit treatment of viscous terms. So far, this drastic increase of resources has hampered the use of SEM for higher polynomial degrees, such as 16 or more.The present contribution is located at this particular “Frontier of CFD” and proposes an SEM with linear scaling in the number of degrees of freedom. It is achieved independent of the polynomial degree, independent of the aspect ratio of elements, and involves constant iteration count when increasing the number of elements. The method is based on combining static condensation with block‐Jacobi preconditioning and iterative substructuring. The latter two lead to a constant iteration count, while the former warrants linear operator complexity.In the presentation, the scheme is described in detail and applied to the construction of a Helmholtz solver. This solver is extremely fast and able to solve the Helmholtz equation with 1010 unknowns on 240 cores in acceptable time. It thus enables competitive high‐order SEM simulations even on small clusters and in this way expands the frontier of CFD towards highly accurate results requiring comparatively modest resources. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)