bluuebunny/crossref_metadata_2025 huggingface dataset:
Surgical management of mesh infection following laparoscopic sacrocolpopexy and tension‐free vaginal mesh surgery: a report of two cases with a literature review
Authors: Sato Hirotaka , Teramoto Sakiko , Sato Katsuhiko , Abe Hirokazu
Published: December 2018

Introduction

The standard management for pelvic abscess or spondylodiscitis after reconstructive surgery previously involved total mesh excision, abscess drainage, and intravenous antibiotic administration. However, only few reports exist regarding the possibility of nonoperative management.

Case presentation

Postoperative mesh infection occurred in two cases of transvaginal mesh and laparoscopic sacrocolpopexy surgery for pelvic organ prolapse. In the first case, intravenous antibiotics were administered and debridement was performed. In the second case, intravenous antibiotics were administered, and local drainage was performed postoperatively, as sacral promontory infiltration was suspected. Diabetes was a comorbidity in both cases.

Conclusion

It is necessary to select patients suitable for vaginal or laparoscopic mesh placement for pelvic organ prolapse preoperatively on the basis of prior history of the patients and once the patients provide informed consent for surgery after being explained the possible complications of pelvic reconstructive surgery, such as mesh infection.
Priming integrin α5 promotes human dental pulp stem cells odontogenic differentiation due to extracellular matrix deposition and amplified extracellular matrix‐receptor activity
Authors: Wang He , Ning Tingting , Song Ci , Luo Xinghong , Xu Shuaimei , Zhang Xiaoyi , Deng Zilong , Ma Dandan , Wu Buling
Published: December 2018

Our previous study showed that knocking down integrin α5 (ITGA5) expression by using a lentiviral vector in human dental pulp stem cells (DPSCs) led to weakening proliferation and migration capacity while enhanced odontogenic differentiation. To seek for possible clinical application, we investigated the effect of the ITGA5 priming synthetic cyclic peptide (SCP; GA‐CRRETAWAC‐GA) on proliferation, migration, and the odontogenic differentiation of DPSCs. Remarkably, the involved mechanism was explored by isobaric tag for relative and absolute quantitation proteomic technique, and the in vivo effect of ITGA5 was investigated by nude mice subcutaneous transplantation of cell and hydroxyapatite/β‐tricalcium phosphate complex. Results showed that SCP weakened the proliferation and migration capacity while enhanced odontogenic differentiation of DPSCs as lentivirus. The phosphorylation of FAK, PI3K/AKT, and MEK1/2/ERK1/2, along with IGF2/IGFBP2 and Wnt/β‐catenin signaling pathway play an important role in this process. Proteomic Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analysis revealed the key role of extracellular matrix (ECM) and ECM‐receptor activity pathway were involved. ECM constituents, secreted protein acidic and cysteine‐rich (SPARC), lumican, vitronectin, prolargin, decorin, collagen type VI α1 chain (COL6A1), COL6A2, COL14A1, and COL5A1 were upregulated in the ITGA5‐silenced group. Inhibited expression of ITGA5 in DPSCs increased osteoid tissue formation and stronger related genes expression in vivo. In conclusion, the ITGA5 priming peptide could promote DPSCs odontogenic differentiation as lentivirus. Proteomics and bioinformatic analysis revealed that this may be due to the deposition of ECM and amplified ECM‐receptor activity, which could fuel the application process of utilizing priming ITGA5 on dental clinical practice.
Population Pharmacokinetic Study and Individual Dose Adjustments of High‐Dose Methotrexate in Chinese Pediatric Patients With Acute Lymphoblastic Leukemia or Osteosarcoma
Authors: Hui Ka Ho , Chu Ho Man , Fong Pui Shan , Cheng Wai Tsoi Frankie , Lam Tai Ning
Published: December 2018

High‐dose methotrexate (>0.5 g/m2) is among the first‐line chemotherapeutic agents used in treating acute lymphoblastic leukemia (ALL) and osteosarcoma in children. Despite rapid hydration, leucovorin rescue, and routine therapeutic drug monitoring, severe toxicity is not uncommon. This study aimed at developing population pharmacokinetic (popPK) models of high‐dose methotrexate for ALL and osteosarcoma and demonstrating the possibility and convenience of popPK model–based individual dose optimization using R and shiny, which is more accessible, efficient, and clinician‐friendly than NONMEM. The final data set consists of 36 ALL (354 observations) and 16 osteosarcoma (585 observations) patients. Covariate model building and parameter estimations were done using NONMEM and Perl‐speaks‐NONMEM. Diagnostic Plots and bootstrapping validated the models’ performance and stability. The dose optimizer developed based on the validated models can obtain identical individual parameter estimates as NONMEM. Compared to calling a NONMEM execution and reading its output, estimating individual parameters within R reduces the execution time from 8.7‐12.8 seconds to 0.4‐1.0 second. For each subject, the dose optimizer can recommend (1) an individualized optimal dose and (2) an individualized range of doses. For osteosarcoma, recommended optimal doses by the optimizer resemble the final doses at which the subjects were eventually stabilized. The dose optimizers developed demonstrated the potential to inform dose adjustments using a model‐based, convenient, and efficient tool for high‐dose methotrexate. Although the dose optimizer is not meant to replace clinical judgment, it provides the clinician with the individual pharmacokinetics perspective by recommending the (range of) optimal dose.
Lots to Do or Lots of Ways to Do It? The Role of Mood and Mind‐set on Goal Motivation
Authors: Han Eunjoo , Gershoff Andrew D.
Published: December 2018

This research explores how mood interacts with outcome and implemental mind‐sets to influence motivation to work toward a goal. We propose and demonstrate that being in a positive (vs. neutral) mood increases motivation for those in an outcome mind‐set. Conversely, being in a positive (vs. neutral) mood decreases motivation for those in an implemental mind‐set. We argue that the reason for this is rooted in the role of positive mood on the number of available goal attainment means: Positive (vs. neutral) mood was found to increase the number of accessible goal attainment activities. For those in an outcome mind‐set, the increased number of goal attainment activities increases motivation because more activities are perceived as more available opportunities or strategies that may aid in successful goal attainment. For those in an implemental mind‐set, where one considers detailed steps and processes required for goal completion, motivation is decreased, because availability of more activities increases perceived difficulty of goal execution. Five studies support these hypotheses, showing differences in available activities depending on mood, differences in perceptions of those activities depending on mind‐set, and differences in motivation depending on the interaction of mood and mind‐set.
[18F]FPyZIDE: A versatile prosthetic reagent for the fluorine‐18 radiolabeling of biologics via copper‐catalyzed or strain‐promoted alkyne‐azide cycloadditions
Authors: Roche Mélanie , Specklin Simon , Richard Mylène , Hinnen Françoise , Génermont Kevin , Kuhnast Bertrand
Published: December 2018

Methods for the radiolabeling of biologics with fluorine‐18 have been of interest for several decades. A common approach consists in the preparation of a prosthetic reagent, a small molecule bearing a fluorine‐18 that is conjugated with the macromolecule to an appropriate function. Click chemistry, and more particularly cycloadditions, is an interesting approach to radiolabel molecules thanks to mild reaction conditions, high yields, low by‐products formation, and strong orthogonality. Moreover, the chemical functions involved in the cycloaddition reaction are stable in the drastic radiofluorination conditions, thus allowing a simple radiosynthetic route to prepare the prosthetic reagent. We report herein the radiosynthesis of 18F‐FPyZIDE, a pyridine‐based azide‐bearing prosthetic reagent. We exemplified its conjugation via copper‐catalyzed cycloaddition (CuAAC) and strain‐promoted cycloaddition (SPAAC) with several terminal alkyne or strained alkyne model compounds.
Caudal musculature in ground sharks, Carcharhiniformes, with remarks on their phylogenetic interrelationships
Authors: de Oliveira Lucas Romero , de Carvalho Marcelo Rodrigues , Soares Mateus Costa
Published: December 2018

Relationships among families of the shark order Carcharhiniformes are still being debated, for example, in relation to the inclusion of hammerhead sharks (Sphyrnidae) and the tiger shark (Galeocerdo cuvier) in the Carcharhinidae. Previous morphological studies have not analyzed the phylogenetic significance of axial caudal muscles among carcharhiniforms. The authors therefore describe here the axial muscles of the tail region (m. epaxialis,m. obliquussuperioris,m. obliquusinferioris,m. flexor caudalis) to better understand their anatomical patterns among carcharhiniform sharks. Our results indicate that the family Pentanchidae, recently separated from scyliorhinids (catsharks), present a similar pattern of caudal muscles to catsharks, indicating their close phylogenetic relationship. Triakids, hemigaleids, leptochariids,Galeocerdo cuvierandPrionace glaucahave a unique pattern in which the medial axial bundle is bulkier than all other caudal axial muscles. Sphyrnids share with carcharhinids a similar pattern of them. obliquussuperioris(approximately the same size as the dorsalm. epaxialis) and have fibers of them. flexor caudalisarranged in a V‐shape. This chevron‐shape is also present on them. flexor caudalisof hemigaleids and leptochariids. Also, sphyrnids and carcharhinids have more slender septa between muscle bundles (more notably in carcharhinids; the only exception isGaleocerdo cuvier, which has the same pattern as sphyrnids). Although being used here as an outgroup, Squaliformes is unique in lacking one of the epaxial bundles. The authors conclude that the caudal axial musculature has greater phylogenetic potential than previously understood.
Quantitative susceptibility mapping detects neovascularization of the epiphyseal cartilage after ischemic injury in a piglet model of legg‐calvé‐perthes disease
Authors: Johnson Casey P. , Wang Luning , Tóth Ferenc , Aruwajoye Olumide , Kirkham Brooke , Carlson Cathy S. , Kim Harry K.W. , Ellermann Jutta M.
Published: December 2018

Background

Legg‐Calvé‐Perthes disease (LCPD) is a childhood hip disorder thought to be caused by disruption of blood supply to the developing femoral head. There is potential for imaging to help assess revascularization of the femoral head.

Purpose

To investigate whether quantitative susceptibility mapping (QSM) can detect neovascularization in the epiphyseal cartilage following ischemic injury to the developing femoral head.

Study Type

Prospective.

Animal Model

Right femoral head ischemia was surgically induced in 6‐week‐old male piglets. The animals were sacrificed 48 hours (n = 3) or 4 weeks (n = 7) following surgery, and the operated and contralateral control femoral heads were harvested for ex vivo MRI.

Field Strength/Sequence

Preclinical 9.4T MRI to acquire susceptibility‐weighted 3D gradient echo (GRE) images with 0.1 mm isotropic spatial resolution.

Assessment

The 3D GRE images were used to manually segment the cartilage overlying the femoral head and were subsequently postprocessed using QSM. Vessel volume, cartilage volume, and vessel density were measured and compared between operated and control femoral heads at each timepoint. Maximum intensity projections of the QSM images were subjectively assessed to identity differences in cartilage canal appearance, location, and density.

Statistical Tests

Paired t‐tests with Bonferroni correction were used (P < 0.008 considered significant).

Results

Increased vascularity of the epiphyseal cartilage following ischemic injury was clearly identified using QSM. No changes were detected 48 hours after surgery. Vessel volume, cartilage volume, and vessel density were all increased in the operated vs. control femoral heads 4 weeks after surgery (P = 0.001, 0.002, and 0.001, respectively). Qualitatively, the increase in vessel density at 4 weeks was due to the formation of new vessels that were organized in a brush‐like orientation in the epiphyseal cartilage, consistent with the histological appearance of neovascularization.

Data Conclusion

QSM can detect neovascularization in the epiphyseal cartilage following ischemic injury to the femoral head.

Level of Evidence: 1

Technical Efficacy: Stage 1

J. Magn. Reson. Imaging 2019;50:106–113.
Role of Virtual Touch Tissue Imaging Quantification in the Assessment of Hepatic Sinusoidal Obstruction Syndrome in a Rat Model
Authors: Han Hao , Yang Jian , Li Xia , Zhuge Yu‐zheng , Zhu Cheng‐kai , Chen Jun , Fu Yao , Wu Min
Published: December 2018

Objectives

To investigate the value of liver stiffness in rats with various degrees of hepatic sinusoidal obstruction syndrome (HSOS) induced by monocrotaline by comparing liver histopathologic findings.

Methods

Seventy rats were randomly divided into a control group (n = 10), a low‐dose monocrotaline group (n = 30), and a high‐dose monocrotaline group (n = 30). After successful modeling, the liver shear wave velocity (SWV) by Virtual Touch tissue imaging quantification (Siemens Medical Solutions, Mountain View, CA) and the alanine aminotransferase (ALT), aspartate aminotransferase (AST), and total bilirubin levels of the groups were obtained on days 3 and 5, and the intergroup differences were compared. Liver histopathologic characteristics were analyzed to evaluate the degrees of HSOS, and the scores were recorded.

Results

On days 3 and 5, the total bilirubin, AST, and ALT, levels and liver SWV in the low‐ and high‐dose groups were elevated; the portal vein velocity (PVV) of these groups was decreased compared with the control group; and the high‐dose rats showed higher serum AST and ALT levels than the low‐dose rats. The high‐dose rats had a lower PVV than the low‐dose rats at day 3. The liver SWV values had significant correlations with the histologic score and PVV. In a multivariate analysis, the liver SWV (β = 0.813; P < .001) was independently associated with the histopathologic score.

Conclusions

Liver stiffness as measured by Virtual Touch tissue imaging quantification increases with the severity of HSOS and can be recommended as a marker for diagnosis and assessment of HSOS.
Impact of Varying Binary Solvent Gradients on the Solubility Parameters of Poly(3‐hexylthiophene)
Authors: Sharp Devin , Taylor Sarah , Andrews McKenna , Boucher David
Published: December 2018

Current methods for estimating the solubility parameters (SPs) of a solute, particularly conjugated polymers and organic semiconductor moieties, suffer from theoretical and computational deficiencies that have led to many questions and investigations that seek improvement in solubility parameter theory. This investigation focuses on the variation of SPs of a protype conjugated polymer, poly(3‐hexylthiophene), using (1) different set of solvents and binary solvent mixtures having a broad range of chemical characteristics, and (2) multiple computational methodologies, for example, functional solubility parameter and Hansen solubility parameter approaches. The results reveal that the choice of solvents and the fitting methodology impact the empirical SPs when using the binary gradient method. The validity of the observed SPs and the relative contributions of the dispersion, polar, and hydrogen‐bonding interactions are further rationalized using linear solvation energy relationship modeling of the solubility data.
Which subsets of an infinite random graph look random?
Authors: Brian Will
Published: December 2018

Given a countable graph, we say a set A of its vertices is universal if it contains every countable graph as an induced subgraph, and A is weakly universal if it contains every finite graph as an induced subgraph. We show that, for almost every graph on , (1) every set of positive upper density is universal, and (2) every set with divergent reciprocal sums is weakly universal. We show that the second result is sharp (i.e., a random graph on will almost surely contain non‐universal sets with divergent reciprocal sums) and, more generally, that neither of these two results holds for a large class of partition regular families.
The Tarski irredundant basis theorem and the finite soluble groups
Authors: Lucchini Andrea , Moscatiello Mariapia
Published: December 2018

Denote by and , respectively, the smallest and the largest cardinality of a minimal generating set of a finite group G. The Tarski irredundant basis theorem implies that for every k with there exist a minimal generating set , an index and in G such that is again a minimal generating set of G. In this case we say that is an immediate descendant of ω. There are several examples of minimal generating sets of cardinality smaller than which have no immediate descendant and so it appears an interesting problem to investigate under which conditions an immediate descendant exists. In this paper we discuss this problem in the case of finite soluble groups.
Comparative study of PTSD treatments finds encouraging symptom improvement
Authors: Enos Gary
Published: December 2018

Newly published research has helped to fill a gap in the comparative analysis of widely used treatments for post‐traumatic stress disorder (PTSD) in military veterans, finding similar efficacy between a psychotherapy and a medication intervention. The findings should assure professionals in treatment programs that work with veterans that they have multiple effective clinical tools at their disposal.
Modified single pedicle reverse adipofascial flap for fingertip reconstruction
Authors: Losco Luigi , Lo Torto Federico , Maruccia Michele , Di Taranto Giuseppe , Ribuffo Diego , Cigna Emanuele
Published: December 2018

Background

Homodigital adipofascial flap is a well‐established method for treating a distal fingertip defect; nonetheless, its use has some limitations. Reconstruction of fingertip injuries, with radial or ulnar tissue loss, may lead to some difficulties in providing an adequate bone coverage. The standard bipedicled technique did not allow the flap to cover the bone exposure without excessive tension. In our series, the reverse adipofascial flap had a single pedicle. The modified technique, because of its improved degree of rotation, granted the flap to reach either radial or ulnar tissue losses.

Patients and Methods

We treated 15 fingertip amputations distal to the lunula (9 Allen's type II and 6 type III), the mean size of defects was 2.7 cm2 (range, 1.8–3.2 cm2), the mean age of patients was 44 years (range, 22–63 years). Quick Disabilities of the Arm, Shoulder, and Hand score and Visual Analogue Scale were evaluated along with a 2‐point discrimination test; the aesthetic satisfaction of the patients was estimated subjectively using a 5‐point Likert scale.

Results

Mean flap size was 3.6 cm2 (range, 2.5–4.2 cm2), primary flap survival was observed in 14 out of 15 cases, partial flap necrosis was observed in 1 case, the nail grew in all fingers in about 6 months. Mean proximal and distal interphalangeal joint motion was 89° (range, 80°–100°) and 71° (range, 65°–80°), respectively. No complications were observed at the donor site. The median static 2‐point discrimination was 4.5 mm (range, 3–8 mm), the mean quick DASH score was 2.6 (range, 0–9.1). All patients returned to work within a mean of 4.4 weeks (range, 4–5 weeks). The follow‐up was 12 months.

Conclusions

Single pedicle reverse adipofascial flap is an effective technique. This modified procedure allows a wider degree of flap rotation; it represents the ultimate arrow in our bow to address some particular defect geometry.
Relative antigenicity of components in vascularized composite allotransplants: An experimental study of microRNAs expression in rat hind limb transplantation model
Authors: Oda Hiroki , Ikeguchi Ryosuke , Aoyama Tomoki , Ohta Souichi , Noguchi Takashi , Kaizawa Yukitoshi , Yurie Hirofumi , Takeuchi Hisataka , Mitsuzawa Sadaki , Yamamoto Koji , Matsuda Shuichi
Published: December 2018

Background

Skin is considered to be the most antigenic component of all vascularized composite allotransplantation tissues. However, no studies have used methods other than histological assessment to analyze the relative antigenicity of various components. In this study, we analyzed gene expression to investigate the relative antigenicity of each component in the transplanted limb.

Methods

Seven Brown Norway rats and 31 Lewis rats were assigned to two groups: an allograft group and a syngeneic (control) group. Brown Norway rats were used as the allogeneic donors, and Lewis rats were used as the syngeneic donors and recipients. About 13 recipients in the allograft group and 12 recipients in the control group were analyzed. Histological assessment was performed in 5 of the recipients in each group, and microRNA expression was analyzed in the remaining recipients, except for 1 recipient in the syngeneic group.

Results

In the allograft group, the relative microRNA‐146a expression was significantly higher in skin (2.34 ± 0.44) than in muscle (1.25 ± 0.22; p = .034) and bone (1; p = .0081). In the allograft group, microRNA‐155 expression was significantly higher in skin (1.91 ± 0.18) than in bone (1; p = .010). Histological assessment showed that some skin tissue in the allograft group showed evidence of severe acute rejection.

Conclusions

The microRNA‐146a and microRNA‐155 seemed to reflect the relative antigenicity during acute rejection of transplanted limbs. Skin seemed to be more antigenic than muscle and bone in both the histological assessment and gene expression analysis.
Expanding the applications of the combined transverse upper gracilis and profunda artery perforator (TUGPAP) flap for extensive defects
Authors: Ciudad Pedro , Huang Tony Chieh‐Ting , Manrique Oscar J. , Agko Mouchammed , Sapountzis Stamatis , Nicoli Fabio , Diya Sabbagh M. , Pont Luis Parra , Moran Steven L. , Chen Hung‐Chi
Published: December 2018

Background

The medial thigh is a well‐hidden area. The two most common flaps from this area are the transverse upper gracilis (TUG) and profunda artery perforator (PAP) flaps. Herein, we explored the applications of combined TUGPAP flap to reconstruct large and complex defects in different regions.

Methods

Between November 2015 and May 2017, 28 patients who underwent reconstruction and extensive soft tissue coverage with the TUGPAP flap for the breasts, head and neck, and pelvi‐perineal regions were included. The defects size ranged from 22 to 29 × 6–8 cm. All flaps were based on the two pedicles: the medial circumflex femoral artery for TUG flap and the profunda artery perforator for PAP flap. They were each anastomosed to a set of recipient vessels. A “Y”‐shaped interposition vein graft (YVG) was used if only one recipient artery was available.

Results

The harvested skin paddle had dimensions ranged from 20 to 30 × 6–9 cm and all flaps survived completely. Postoperative complications included one case each of donor and recipient site seroma, and one case of wound dehiscence. They were all successfully managed conservatively. During an average follow‐up period of 12.7 months, one patient reported permanent paresthesia in the donor site and another developed hypertrophic scar. All patients were able to resume daily activity without major concerns.

Conclusion

The combined TUGPAP flap is a safe, effective, and a good alternative to the common workhorse flaps as it offers the potential for a large skin paddle and decent soft tissue volume with low donor site morbidity in a well‐concealed area.
Impacts of TV and radio advertisements on the dynamics of an infectious disease: A modeling study
Authors: Misra Arvind Kumar , Rai Rajanish Kumar
Published: December 2018

TV and radio advertisements are widely acknowledged as important interventions in raising issues of public health care and play promising role to control the infection through propagating awareness among the individuals. In this paper, a nonlinear susceptible‐infected‐susceptible (SIS) model is proposed and analyzed to see the impacts of TV and radio advertisements on the spread of influenza epidemic. In the model formulation, it is assumed that the susceptible individuals contract infection through the direct contact with infected individuals. The information regarding the protection against the disease is propagated via TV and radio advertisements, and their growth rates are assumed to be proportional to the fraction of infected individuals. However, the growth rate of TV advertisements decreases with the increase in number of aware individuals. The information broadcasted through TV and radio advertisements induces behavioral changes among the susceptible individuals, and they form an isolated aware class. The epidemiological feasible equilibria, their stability properties, and direction of bifurcation are discussed. The expression for modified basic reproduction number is obtained. The model analysis shows that the dissemination rate of awareness among susceptible individuals due to TV and radio advertisements and baseline number of TV and radio advertisements have potential to reduce the epidemic peak and, thus, control the spread of infection. Further, the analytical findings are well supported through numerical simulation.
Computing arbitrary Lagrangian Eulerian maps for evolving surfaces
Authors: Kovács Balázs
Published: December 2018

The good mesh quality of a discretized closed evolving surface is often compromised during time evolution. In recent years this phenomenon has been theoretically addressed in a few ways, one of them uses arbitrary Lagrangian Eulerian (ALE) maps. However, the numerical computation of such maps still remained an unsolved problem in the literature. An approach, using differential algebraic problems, is proposed here to numerically compute an arbitrary Lagrangian Eulerian map, which preserves the mesh properties over time. The ALE velocity is obtained by finding an equilibrium of a simple spring system, based on the connectivity of the nodes in the mesh. We also consider the algorithmic question of constructing acute surface meshes. We present various numerical experiments illustrating the good properties of the obtained meshes and the low computational cost of the proposed approach.
On operator norm convergence in time‐dependent homogenisation problems
Authors: Waurick Marcus
Published: December 2018

Using the d‐dimensional wave equation as a prime example, we shall show that an elementary functional analytic theorem for compact operators leads to operator norm convergence of the solution operators of the homogenisation for the wave equation considered as operators in space‐time. The results imply convergence of the amplitude functions locally in L2 with respect to the temporal and globally in L2 with respect to the spatial variables.
Application of the Finite Cell Method to Tunnel Engineering Simulation
Authors: Bui Hoang‐Giang , Meschke Günther , Schillinger Dominik
Published: December 2018

The Finite Cell Method (FCM) is an embedded domain method, in which the simulation domain is divided into a physical domain and a fictitious domain. The adaptive quadrature scheme employs the quad‐tree (oct‐tree in 3D) data structure to generate the quadrature points up to the specified level around the material boundary. In this paper, the FCM is applied for machine driven tunnel advancement simulations [1]. The geometry of the excavation volume is embedded into a background mesh by employing the B‐Rep concept. The mesh for the soil volume is structured and is fixed during the tunnel advancement. The tunnel lining is embedded in the soil mesh as a surface mesh, which incorporates the shell element formulation. In terms of the material description, the soil is represented as a saturated two‐phase medium [2], which consists of the soil matrix and the pore water. The effective stress of the soil is governed by means of the elastoplastic Mohr‐Coulomb constitutive model. Selected numerical benchmarks are performed to demonstrate the performance of the proposed method.
On the Accuracy of the Element‐wise Jacobi Methods for PGEP
Authors: Matejaš Josip , Hari Vjeran
Published: December 2018

We analyze the relative accuracy of two new element‐wise Jacobi‐type methods for the positive definite generalized eigenvalue problem Ax = λBx, where A and B are symmetric matrices and B is positive definite. A detailed error analysis is used, and the appropriate numerical tests are performed. If A and B are well‐behaved positive definite matrices then the transformation parameters will have small relative errors and numerical tests indicate the high relative accuracy of the methods.
Residence time optimization of spin pack polymer distributors
Authors: Hohmann Raphael , Leithäuser Christian
Published: December 2018

We consider the optimal shape design of polymer distributors used for industrial fiber spinning. In this laminar flow problem the residence time, the volume‐averaged age distribution of the fluid particles, has to be controlled to avoid material degradation. The residence time is modelled by an advection‐diffusion‐reaction equation with the fluid velocity being the transport field. This approach is more suitable for PDE‐constrained shape optimization than the Lagrangian particle‐tracking approach, where the observable is a finite set of trajectories. In order to develop an efficient shape optimization algorithm we derive the shape gradient of a tracking‐type cost functional by introducing the adjoint state.
Fault tolerant funnel control
Authors: Berger Thomas
Published: December 2018

A new approach to adaptive fault tolerant tracking control for uncertain linear systems is presented. Based on recent results in funnel control and the time‐varying Byrnes‐Isidori form, we introduce a low‐complexity model‐free controller which achieves prescribed performance of the tracking error for any given sufficiently smooth reference signal. Within the considered system class, we allow for more inputs than outputs as long as a certain redundancy of the actuators is satisfied. An important role in the controller design is played by the controller weight matrix, which is a rectangular input transformation chosen such that in the resulting system the zero dynamics, which are assumed to be uniformly exponentially stable, are independent of the new input.
Funnel control for overhead crane model
Authors: Berger Thomas , Lê Huy Hoàng , Reis Timo
Published: December 2018

We consider an overhead crane whose control variables are the length of the rope and force/velocity at the gantry. The output consists of the position of the load. The objective is to design a closed‐loop tracking controller which also takes into account the transient behavior. First we show that this system has no well‐defined relative degree, which unfortunately does not allow to apply established methods for adaptive control to achieve the objective. To circumvent this problem, we design a dynamic state feedback which results in a system with relative degree four. Thereafter, we apply a funnel controller to this feedback system. We show that our approach can be used to move loads from one to another given position in the situation where there are several obstacles which have to be circumnavigated.
Thermally assembled shrink fit with annular inclusion and FGM‐hub
Authors: Apatay Tunç , Arslan Eray , Mack Werner
Published: December 2018

Subject of the investigation is an elastic shrink fit with annular inclusion and functionally graded hub in a state of generalized plane strain. By appropriate grading both a substantial weight reduction and an improved performance at rotation can be achieved. In this contribution, special attention is paid also to the thermal assembly. In particular, numerical results are given for a steel/aluminum FGM‐hub.
Multiple goal‐oriented error estimates applied to 3d non‐linear problems
Authors: Endtmayer Bernhard , Langer Ulrich , Wick Thomas
Published: December 2018

In this work, we provide goal oriented error estimates for multiple (possibly) non‐linear functionals for a nonlinear partial differential equation. We combine the functionals in a certain way, and apply the dual weighted residual method using a partition of unity for localization. Finally, we provide a numerical example.
Investigation of the behaviour of a Newtonian liquid regarding the picture framing coating error
Authors: Sommer Oliver , Hehemann Sven , Wozniak Günter
Published: December 2018

We experimentally investigated the specific behaviour of Newtonian thin liquid layers at curved solid edges in a continuative investigation of the so‐called picture framing effect coating error. We used adapted laser‐induced fluorescence technique (LIF) to measure the layer thickness distribution for the examination of the underlying edge bead in a cross section. The main motivation is to find optimal combinations of influencing quantities to reduce the picture framing effect (edge beads) in order to achieve a homogeneous layer thickness distribution of the liquid coating on the surface of the substrate, especially at the edges. For this purpose, we varied the viscosity of the Newtonian liquid, the edge radii of curvature of the substrate and its orientation regarding the gravitational direction. The results, i.e. the edge bead dependencies on the tested parameters, are physically plausible. With these findings the picture framing effect as a whole is manipulable regarding a minimisation of the coating error.
Investigation of size effects due to material interfaces
Authors: Heitbreder Tim , Ottosen Niels Saabye , Ristinmaa Matti , Mosler Jörn
Published: December 2018

The thermodynamical consistent combination of classical non‐coherent cohesive zone models with surface elasticity theory is relatively new, cf. [1]. Relying on the variational structure of the underlying problem, a compact and direct derivation of the framework [1] is presented. By embedding the framework into the finite element method, the mechanical influence of interfaces within RVEs is investigated for different sizes. Thereby, a complex size effect combining the frequently observed “the smaller the stiffer" relation, but also the less often observed “the smaller the softer" relation is worked out. A combination of the both relations leads to a non‐monotonic size effect, that is influenced by the choice of the interface material parameter, see [2].
Study of model variants in a combined framework for multiplicative growth and remodeling in arterial walls
Authors: Zahn Anna , Balzani Daniel
Published: December 2018

A combined framework for stress‐induced growth and fiber reorientation in arterial walls is presented. Assuming that the reduction of stress peaks and gradients in different loading situations is the main purpose of an effective adaptation process, a simplified study of model variants is performed on idealized arterial geometries.
Balancing Related Model Reduction with the MORLAB Toolbox
Authors: Benner Peter , Werner Steffen W. R.
Published: December 2018

Balancing related model reduction methods are based on the idea of the balanced truncation method and can be used to preserve certain system properties like passivity or contractivity. The MORLAB toolbox provides efficient implementations for a big set of such methods. We will give an overview about the implemented methods and test some of these methods on a benchmark example.
A Data‐Driven Possibilistic Approach to the Identification of Uncertain Stability Lobe Diagrams
Authors: Hose Dominik , Hamann Dominik , Hanss Michael , Eberhard Peter
Published: December 2018

In this contribution, an alternative approach to classical regression analysis is explored which allows the identification of uncertain stability lobe diagrams for machining processes via a multi‐fidelity modeling approach.
Multi‐level preconditioning and eigenvector approximation for axisymmetric Maxwell eigenproblems
Authors: Kranjčević Marija , Arbenz Peter , Adelmann Andreas
Published: December 2018

We compute resonant modes in axisymmetric radio frequency cavities by solving a few generalized eigenvalue problems using the symmetric Jacobi–Davidson algorithm. In particular, we focus on the parallelization and the use of the multi‐level preconditioner for the correction equation. Additionally, we compute eigenvector approximations using the solutions of the problem on a coarser mesh and present the results on the problem of computing a few lowest modes of a real‐world cavity.
Development of a passive, wearable knee orthosis for the support of sit‐to‐stand movement with adaptive assistance moment
Authors: Ziegler Jakob , Parzer Herbert , Gattringer Hubert , Müller Andreas
Published: December 2018

The worldwide population aging and hence the higher risk of age‐related diseases facilitates interest in robotic devices for rehabilitation and movement assistance. A major factor of a persons functional independence is the ability to perform the movement task of standing up from a chair, also known as sit‐to‐stand (STS) movement. This work focuses on the development of a passive, wearable knee orthosis that supports the extension of the knee joint. As the knee flexes while sitting down a spring mechanism is loaded due to a cable wrapping around a deflection disc, thus generating a moment that assists standing up again. In order to prevent unintended knee extension this assistance moment should be minimized when the person is fully seated. To this end the geometry of the deflection disc, parametrized as B‐spline curve, is optimized in order to control the knee extension moment with respect to the knee angle. Initial tests with a first prototype show promising results.
A Virtual Element Method for Crack Propagation
Authors: Hussein Ali , Hudobivnik Blaž , Aldakheel Fadi , Wriggers Peter , Guidault Pierre‐Alain , Allix Olivier
Published: December 2018

In this contribution, a crack propagation within brittle materials is presented by means of a novel technique, the virtual element method (VEM) [1]. In comparison to FEM, VEM allows usage of arbitrary polygonal (2D) and polyhedral (3D) elements. Such a method can be extremely useful for simulation of crack propagation problems, which may be providing an alternative approach for XFEM and remeshing. Based on the stress intensity factor, calculated by the interaction integral, the direction of the crack propagation is predicted by using the maximum circumferential stress criterion. For domain discretization, we used arbitrary polygonal elements with arbitrary number of nodes. Without changing the element formulations, the crack path is constructed by splitting the elements in the direction of growth. Also, if the crack growth stops within the element, this can be easily accomplished. Finally, a numerical example is provided to demonstrate the performance of the model.
Coupled simulations involving light‐weight structures within turbulent flows: FSI strategy and non‐matching interface treatment for isogeometric b‐rep analysis
Authors: Wüchner Roland , Apostolatos Andreas , De Nayer Guillaume , Breuer Michael , Bletzinger Kai‐Uwe
Published: December 2018

Lightweight shell structures have gained significant popularity in the engineering design as they offer high load carrying capacity for low cost. While classical Finite Element models of such structures have been extensively used in practice, the shell formulations for Isogeometric Analysis (IGA), particularly for Kirchhoff‐Love shell structures [1], have demonstrated benefits arising from the smooth geometry description and the highly accurate solutions that are enabled. Moreover, the direct use of CAD‐models for the structural simulations is possible based e.g. on the Isogeometric B‐Rep Analysis (IBRA) [2]. Herein the application of IBRA to Fluid‐Structure Interaction (FSI) simulations of wind turbines is demonstrated, thus naturally extending IBRA to coupled multiphysics problems.
A probability‐box approach on uncertain correlation lengths by stochastic finite element method
Authors: Dannert Mona M. , Fau Amelie , Fleury Rodolfo M.N. , Broggi Matteo , Nackenhorst Udo , Beer Michael
Published: December 2018

In order to regard mixed aleatory and epistemically uncertain random fields within stochastic finite element method, a probability box approach using stochastic collocation method is introduced. The influence of an interval‐valued correlation length on the output is investigated.
A numerically robust anisotropic damage model
Authors: Fassin Marek , Eggersmann Robert , Wulfinghoff Stephan , Reese Stefanie
Published: December 2018

The present work deals with an elastic‐brittle anisotropic damage model utilizing a second order damage tensor. Artificial stiffening effects are excluded a priori by means of a specific choice of the elastic part of the free energy. Two strategies for the determination of the internal variables are investigated: (i) standard approach based on the evolution equations of the internal variables and (ii) use of a regularized dissipation potential (within the concept of generalized standard materials). The superior robustness of the latter approach is exemplarily shown with a convergence study of a uniaxial stretch test.
Analytical modelling of autofrettage processes – Historical approaches and new results
Authors: Rammerstorfer Franz G. , Bauer Stefan , Scheidl Jakob
Published: December 2018

There exist a number of classical analytical solutions for the calculation of the residual stresses produced by autofrettage. Historical solutions for thick‐walled tubes are based on assumptions, which are approximate in comparison with reality and limited in the range of applicability. New results for realistic boundary conditions reveal some unexpected phenomena.
Crack detection and parameter identification in finite and semi‐ infinite plane structures based on remote strain fields and the distributed dislocation technique
Authors: Boukellif Ramdane , Ricoeur Andreas
Published: December 2018

A method for the detection of cracks in finite and semi‐infinite plane structures is presented. This allows both the identification of crack position parameters, such as length, location and angles with respect to a reference coordinate system and the calculation of stress intensity factors (SIFs). The method is based on strains measured at different locations on the surface of a structure and the application of the dislocation technique. Cracks and boundaries are modelled by continuous distributions of dislocation densities. This approach gives a set of singular integral equations with Cauchy kernels, which can be solved using Gauss‐Chebyshev numerical quadrature. Once knowing the dislocation densities, the strain at an arbitrary point can be calculated. The crack parameters as well as external loads are parameters which have to be determined by solving the inverse problem with a genetic algorithm. Once knowing loading and crack parameters, the SIFs can be calculated.
Flame propagation in arbitrarily shaped vessels
Authors: Gößnitzer Clemens , Steinrück Herbert
Published: December 2018

A new method to capture the flame front in premixed, confined, low Mach number combustion using the flame‐sheet approximation is presented. Connected marker points represent the flame front along which a singular volumetric flux source is prescribed. Thus, the jump condition for the normal velocity is fulfilled. Application to two‐dimensional combustion in a channel with periodic boundary conditions shows good agreement to linear stability analysis of the perturbed flame front.
Prescribed Performance Adaptive Control of Uncertain Nonlinear Systems: State‐of‐the‐art and Open Issues
Authors: Rovithakis George A.
Published: December 2018

Performance in adaptive control designs for uncertain nonlinear systems, whose uncertainty is not purely parametric, was traditionally restricted to enforcing, besides stability, desirable behavior at steady‐state. In the literature, rigorous proofs have been provided guaranteeing tracking error convergence to residual sets, whose size depends on design parameters and some bounded though unknown terms. Therefore, even controllable, steady‐state accuracy was impossible to be a priori selected by any systematic procedure. Furthermore, transient performance such as maximum overshoot and convergence rate, was difficult to be established analytically even for known systems. The problem was approached via minimizing certain performance indices, which unfortunately were connected only indirectly with the actual system response. Hence, even though performance improvement is anticipated, no connection to a priori specified trajectory oriented metrics could be achieved. For classes of nonlinear systems Funnel Control has been proposed to provide solution. However, the problem remained largely unsolved for the case of adaptive closed‐loop uncertain systems. To fill in the gap, the Prescribed Performance Control (PPC) methodology was presented. This work is a review on PPC, highlighting on its main advantages and discussing on probably the most important open issues.
Parameter Optimization of a Reduced Model for Multi‐Contact Locomotion of Humanoid Robots
Authors: Seiwald Philipp , Leyerer Anian , Sygulla Felix , Rixen Daniel
Published: December 2018

In this study, we investigate a reduced model intended for approximating the complex multi‐body dynamics of our full‐sized humanoid robot LOLA. In particular, we compare various optimization algorithms to find an optimal set of model parameters. For rating parameter sets, we define a cost function which penalizes differences between the simulated motion of the full‐ and reduced model. Due to the complex motions of a walking humanoid robot, which includes cyclic opening and closing contacts, one is easily trapped in local minima. Thus the focus of this study lies on techniques for global optimization based on meta‐heuristics. We plan to use the reduced model for real‐time stability analysis during multi‐contact locomotion, i. e. walking with additional arm support.
Hygro‐thermo‐chemo‐mechanical modelling of shotcrete during tunnel advance
Authors: Gamnitzer Peter , Schreter Magdalena , Hofstetter Günter
Published: December 2018

This contribution deals with numerical modelling of drill‐and‐blast tunnelling. Special attention is paid to the modelling of a shotcrete layer supporting the surrounding rock after excavation. Due to an increasing load caused by further tunnel advance, and due to shrinkage caused by hydration which is restrained by the surrounding rock, the shotcrete is loaded in place at a very early age. Hence it is required to accurately model the evolution of its strength and stiffness. This is done using a fully coupled hygro‐thermo‐chemo‐mechanical multi‐phase model for the shotcrete. Creep of shotcrete is taken into account using a microprestress‐solidification approach. The constitutive model for the shotcrete is calibrated using experimental data obtained from laboratory tests reported in literature. The setup for the tunnelling simulation is completed assuming elastic‐plastic response for the surrounding rock and the additional steel anchors. The results of this contribution are considered to be a further step towards a more accurate modelling of excavation procedures in conventional drill‐and‐blast tunnelling.