bluuebunny/crossref_metadata_2025 huggingface dataset:
Predictors of adherence to treatment by patients with coronary heart disease after percutaneous coronary intervention
Authors: Kähkönen Outi , Saaranen Terhi , Kankkunen Päivi , Lamidi Marja‐Leena , Kyngäs Helvi , Miettinen Heikki
Published: November 2017

Aims and objectives

To identify the predictors of adherence in patients with coronary heart disease after a percutaneous coronary intervention.

Background

Adherence is a key factor in preventing the progression of coronary heart disease.

Design

An analytical multihospital survey study.

Methods

A survey of 416 postpercutaneous coronary intervention patients was conducted in 2013, using the Adherence of People with Chronic Disease Instrument. The instrument consists of 37 items measuring adherence and 18 items comprising sociodemographic, health behavioural and disease‐specific factors. Adherence consisted of two mean sum variables: adherence to medication and a healthy lifestyle. Based on earlier studies, nine mean sum variables known to explain adherence were responsibility, cooperation, support from next of kin, sense of normality, motivation, results of care, support from nurses and physicians, and fear of complications. Frequencies and percentages were used to describe the data, cross‐tabulation to find statistically significant background variables and multivariate logistic regression to confirm standardised predictors of adherence.

Results

Patients reported good adherence. However, there was inconsistency between adherence to a healthy lifestyle and health behaviours. Gender, close personal relationship, length of education, physical activity, vegetable and alcohol consumption, LDL cholesterol and duration of coronary heart disease without previous percutaneous coronary intervention were predictors of adherence.

Conclusions

The predictive factors known to explain adherence to treatment were male gender, close personal relationship, longer education, lower LDL cholesterol and longer duration of coronary heart disease without previous percutaneous coronary intervention.

Relevance to clinical practice

Because a healthy lifestyle predicted factors known to explain adherence, these issues should be emphasised particularly for female patients not in a close personal relationship, with low education and a shorter coronary heart disease duration with previous coronary intervention.
Producing the Product: A Case Study of Law and Its Absence
Authors: Carr Helen , Cowan Dave , Wallace Alison
Published: November 2017

In this article, we seek to develop socio‐legal studies through a rupturing of the ideas behind the social and the legal, ideas that are most often presumed to exist and are used to explain that which is already there. The ubiquity of law and the omniscience of society have become givens. We use a product called shared ownership as a case study, arguing that the product was given life by a legal document (the lease) which itself represented the translation of a range of different perspectives and audiences (albeit not the consumer), and which, itself, has been translated, most notably in a 2008 High Court decision. That decision counterintuitively found that the lease had created an assured shorthold tenancy (albeit a long one) but, despite its threat to the product, has been largely ignored. We discuss the processes of, and reasons for, the translation through which that ignorance has been induced.
Eyes of the Law: A Visual Turn in Socio‐Legal Studies?
Authors: Mulcahy Linda
Published: November 2017

A number of sub‐disciplines have emerged in recent years with the specific goal of examining the visual dynamics of academic fields of inquiry. The turn to the visual masks a multitude of meanings about the significance of the image, ranging from new ways of defining a field of inquiry, to what constitutes legitimate sources for research or discussions of image production or visual prompts as a data collection method. This article asks what it means for socio‐legal scholars to engage with the image and the opportunity it might provide us with to see what law looks like from the perspective of law's subjects. These might include art installations in galleries, images of the places where justice is administered as well as photographs created by those who are subjected to legal regulation. In addition to a written essay I offer up three visual essays which can be read and contemplated with or without the written text which accompanies them.
An Examined Life: Research into University Legal Education in the United Kingdom and the Journal of Law and Society
Authors: Cownie Fiona , Bradney Anthony
Published: November 2017

For academics, the nature of their work means that the Socratic demand to live an examined life has a particular force. In this article we look at the extent to which those working in university law schools in England and Wales have lived up to this suggestion, in the context of assessing the nature and quality of work on university legal education from the beginnings of university law schools. In doing so, we respond to the comments on such work in the REF 2014 law sub‐panel report and make some suggestions about likely future developments in the field.
Dose-dependent effect of triiodothyronine on the chondrogenic differentiation of mesenchymal stem cells from the bone marrow of female rats
Authors: Assis Higor A , Elert Nathalia C , Azevedo André Luiz B P , Braga Iolanda S , Serakides Rogéria , de Melo Ocarino Natália , de Goes Alfredo M , de Paula Careta Francisco , Paneto Greiciane G , da Silva Adriana M A , Boeloni Jankerle N
Published: November 2017

Objectives

Verify the in-vitro effect of triiodothyronine (T3) on the chondrogenic differentiation of female rat bone marrow mesenchymal stem cells (BMMSCs) over several time periods and at several doses.

Methods

CD54 + /CD73 + /CD90 + BMMSCs from Wistar female rats were cultured in chondrogenic medium with or without T3 (0.01; 1; 100; 1000 nm). At seven, 14 and 21 days, the cell morphology, chondrogenic matrix formation and expression of Sox9 and collagen II were evaluated.

Key findings

The dose of 100 nm did not alter the parameters evaluated in any of the periods studied. However, the 0.01 nm T3 dose improved the chondrogenic potential by increasing the chondrogenic matrix formation and expression of Sox9 and collagen II in at least one of the evaluated periods; the 1 nm T3 dose also improved the chondrogenic potential by increasing the chondrogenic matrix formation and the expression of collagen II in at least one of the evaluated periods. The 1000 nm T3 dose improved the chondrogenic potential by increasing the chondrogenic matrix formation and Sox9 expression in at least one of the evaluated periods.

Conclusions

T3 has a dose-dependent effect on the differentiation of BMMSCs from female rats.
Evaluating the nutritive profile of three insect meals and their effects to replace soya bean in broiler diet
Authors: Khan S. , Khan R. U. , Alam W. , Sultan A.
Published: November 2017

This study was conducted to evaluate the comparative effect of maggot meal, silkworm meal and mealworm as dietary protein source on the production performance and some aspects of meat quality in broilers. In this regard, maggot meal was reared on chicken offal and poultry waste. Silkworm meal was obtained from silk industry, while mealworm was developed through beetles rearing. A total of 120‐day‐old broiler chicks were randomly divided into four groups where soya bean meal (M0) was replaced with maggot meal (M1), silkworm meal (M2) and mealworm (M3) respectively. Each group was further divided into three replicates. The study was carried out for a period of 5 weeks. Diets containing mealworm significantly reduced overall feed consumption and resulted into higher weight gain (p < .05). Lowest feed conversion ratio (FCR) was recorded for birds fed with mealworm diet (p < .05). Tenderness and juiciness of meat were higher (p < .05) in M3 compared to the control and other treatments. Mortality did not vary between the control and the treated groups. Therefore, it is concluded that insect meal is rich in essential nutrients and could be successfully used in broiler ration without compromising acceptability. In the light of this study, mealworm is the best choice in broiler ration, in comparison with maggot and silkworm.
A 6‐bp Deletion Variant in a Novel Canine Glutathione‐S‐Transferase Gene (GSTT5) Leads to Loss of Enzyme Function
Authors: Craft S. , Ekena J. , Sacco J. , Luethcke K. , Trepanier L.
Published: November 2017

Objectives

Glutathione‐S‐transferases (GSTs) detoxify reactive xenobiotics, and defective GST gene polymorphisms increase cancer risk in humans. A low activity GST‐theta variant was previously found in research beagles. The purpose of our study was to determine the molecular basis for this phenotype and its allele frequency in pet dogs.

Methods

Banked livers from 45 dogs of various breeds were screened for low GST‐theta activity by the substrate 1,2‐dichloro‐4‐nitrobenzene (DCNB), and were genotyped for variants in a novel canine GST gene, GSTT5. Whole‐genome sequences from 266 dogs were genotyped at one discovered variant GSTT5 locus.

Results

Canine livers ranged 190‐fold in GST‐theta activities, and a GSTT5 exon coding variant 385_390delGACCAG (Asp129_Gln130del) was significantly associated with low activity (P < 0.0001) and a marked decrease in hepatic protein expression (P = 0.0026). Recombinant expression of variant GSTT5 led to a 92% decrease in Vmax for DCNB (P = 0.0095). The minor allele frequency (MAF) for 385_390delGACCAG was 0.144 in 45 dog livers, but was significantly higher in beagles (0.444) versus nonbeagles (0.007; P = 0.0004). The homozygous genotype was significantly over‐represented in Pembroke Welsh corgis (P < 0.0001) based on available whole‐genome sequence data.

Conclusions

An Asp129_Gln130del variant in canine GSTT5 is responsible for marked loss of GST‐theta enzyme activity. This variant is significantly over‐represented in purpose‐bred laboratory beagles and in Pembroke Welsh corgis. Additional work will determine the prevalence of this variant among other purebred dogs, and will establish the substrate range of this polymorphic canine enzyme with respect to common environmental carcinogens.
The cotton MAPK kinase GhMPK20 negatively regulates resistance to Fusarium oxysporum by mediating the MKK4–MPK20–WRKY40 cascade
Authors: Wang Chen , He Xiaowen , Li Yuzhen , Wang Lijun , Guo Xulei , Guo Xingqi
Published: November 2017

Fusarium wilt is one of the most serious diseases affecting cotton. However, the pathogenesis and mechanism by which Fusarium oxysporum overcomes plant defence responses are unclear. Here, a new group D mitogen‐activated protein kinase (MAPK) gene, GhMPK20, was identified and functionally analysed in cotton. GhMPK20 expression was significantly induced by F. oxysporum. Virus‐induced gene silencing (VIGS) of GhMPK20 in cotton increased the tolerance to F. oxysporum, whereas ectopic GhMPK20 overexpression in Nicotiana benthamiana reduced F. oxysporum resistance via disruption of the salicylic acid (SA)‐mediated defence pathway. More importantly, an F. oxysporum‐induced MAPK cascade pathway composed of GhMKK4, GhMPK20 and GhWRKY40 was identified. VIGS of GhMKK4 and GhWRKY40 also enhanced F. oxysporum resistance in cotton, and the function of GhMKK4–GhMPK20 was shown to be essential for F. oxysporum‐induced GhWRKY40 expression. Together, our results indicate that the GhMKK4–GhMPK20–GhWRKY40 cascade in cotton plays an important role in the pathogenesis of F. oxysporum. This research broadens our knowledge of the negative role of the MAPK cascade in disease resistance in cotton and provides an important scientific basis for the formulation of Fusarium wilt prevention strategies.
The relationship between esophageal acid exposure and the esophageal response to volumetric distention
Authors: Carlson D. A. , Kathpalia P. , Craft J. , Tye M. , Lin Z. , Kahrilas P. J. , Pandolfino J. E.
Published: November 2017

Background

Increased esophagogastric junction (EGJ) distensibility is thought to contribute to gastroesophageal reflux disease (GERD). Using the functional lumen imaging probe (FLIP), we aimed to assess the esophageal response to distension among patients undergoing esophageal pH monitoring.

Methods

25 patients (ages 22‐73; 13 females) who underwent ambulatory wireless esophageal pH testing while off proton‐pump inhibitors were evaluated with FLIP during sedated upper endoscopy. Esophageal reflux was quantified by total percent acid exposure time (AET; <6% was considered normal). FLIP studies were analyzed using a customized program generate FLIP topography plots to identify esophageal contractility patterns and to calculate the EGJ‐distensibility index (DI). Reflux symptoms were assessed with the GERDQ. Values reflect median (interquartile range).

Results

Among all patients, the AET was 7.2% (3.7‐11.1) and EGJ‐DI was 4.2 (2.5‐7.6) mm2/mm Hg. Repetitive antegrade contractions (RACs) were induced in 19/25 (76%) of patients; AET was lower among patients with (6.1%, 3‐7.8) than without (14.9, 8.5‐22.3) RACs (P = .009). Correlation was weak and insignificant between AET and EGJ‐DI, GERDQ and AET, and GERDQ and EGJ‐DI. Patients with abnormal AET (n = 16) and normal AET (n = 9) had similar EGJ‐DI, 4.6 mm2/mm Hg (2.9‐9.2) vs 3.2 (2.2‐5.1), P = .207 and GERDQ, P = .138.

Conclusions

Abnormal esophageal acid exposure was associated with an impaired contractile response to volume distention of the esophagus. This supports that acid exposure is dependent on acid clearance mechanisms.
A role for the gene regulatory module microRNA172/TARGET OF EARLY ACTIVATION TAGGED 1/FLOWERING LOCUS T (miRNA172/TOE1/FT) in the feeding sites induced by Meloidogyne javanica in Arabidopsis thaliana
Authors: Díaz‐Manzano Fernando E. , Cabrera Javier , Ripoll Juan‐José , del Olmo Iván , Andrés Mari Fe , Silva Ana Cláudia , Barcala Marta , Sánchez María , Ruíz‐Ferrer Virginia , de Almeida‐Engler Janice , Yanofsky Martin F. , Piñeiro Manuel , Jarillo Jose Antonio , Fenoll Carmen , Escobar Carolina
Published: November 2017

Root knot nematodes (RKNs) penetrate into the root vascular cylinder, triggering morphogenetic changes to induce galls, de novo formed ‘pseudo‐organs’ containing several giant cells (GCs). Distinctive gene repression events observed in early gall/GCs development are thought to be mediated by post‐transcriptional silencing via microRNAs (miRNAs), a process that is far from being fully characterized.

Arabidopsis thaliana backgrounds with altered activities based on target 35S::MIMICRY172 (MIM172), 35S::TARGET OF EARLY ACTIVATION TAGGED 1 (TOE1)‐miR172‐resistant (35S::TOE1R) and mutant (flowering locus T‐10 (ft‐10)) lines were used for functional analysis of nematode infective and reproductive parameters. The GUS‐reporter lines, MIR172A–E::GUS, treated with auxin (IAA) and an auxin‐inhibitor (a‐(phenyl ethyl‐2‐one)‐indole‐3‐acetic acid (PEO‐IAA)), together with the MIR172C AuxRE::GUS line with two mutated auxin responsive elements (AuxREs), were assayed for nematode‐dependent gene expression.

Arabidopsis thaliana backgrounds with altered expression of miRNA172, TOE1 or FT showed lower susceptibility to the RKNs and smaller galls and GCs. MIR172C−D::GUS showed restricted promoter activity in galls/GCs that was regulated by auxins through auxin‐responsive factors. IAA induced their activity in galls while PEO‐IAA treatment and mutations in AuxRe motifs abolished it.

The results showed that the regulatory module miRNA172/TOE1/FT plays an important role in correct GCs and gall development, where miRNA172 is modulated by auxins.
Prediction in ecology: promises, obstacles and clarifications
Authors: Maris Virginie , Huneman Philippe , Coreau Audrey , Kéfi Sonia , Pradel Roger , Devictor Vincent
Published: November 2017

In the current context of global change and a biodiversity crisis, there are increasing demands for greater predictive power in ecology, in both the scientific literature and at the science–policy interface. The implicit assumption is that this will increase knowledge and, in turn, lead to better decision‐making. However, the justification for this assumption remains uncertain, not least because the definition of ‘prediction’ is unclear. We propose that two types of prediction should be distinguished: corroboratory‐prediction is linked to the validation of theories; and anticipatory‐prediction is linked to the description of possible futures. We then discuss four families of obstacles to prediction, linked to the specific features of ecosystems: 1) they are historical entities, 2) they are complex, 3) their dynamics are stochastic, and 4) they are influenced by socio‐economic drivers. A naïve understanding of ecological science suggests that the two types of predictions are simply two phases in a sequence in which scientists first improve their knowledge of ecological systems via corroboratory‐predictions, and then apply this knowledge in order to forecast future states of ecosystems via anticipatory‐predictions in order to help policy makers taking decisions. This sequence is however not straightforward, partly because corroboration and anticipation are not affected by the obstacles to prediction in the same way. We thus invite to reconsider the role of ecological prediction as a tool in a deliberative model of decision‐making rather than as external scientific information aimed at enlightening the political process. Doing so would be beneficial for both the policy‐relevance of anticipatory‐prediction and the theoretical‐relevance of corroboratory‐prediction.
Assessing fitness parameters of hybrids between weed beets and transgenic sugar beets
Authors: Vigouroux Yves , Darmency Henri
Published: November 2017

Herbicide resistance is a desired trait for sugar beet (Beta vulgaris L.) production because it is a low‐competitor crop that requires careful weed management. However, gene flow to weed beet (also B. vulgaris) could jeopardize the weed control strategy by causing the emergence of resistant weed beets; it could also lead to further adaptation of weed beet as a troublesome weed for other crops by selecting more competitive plants. To evaluate the hazard that such a selection process represents, apart the herbicide resistance, we investigated the morphology and reproduction of progeny of weed beets having inherited a herbicide resistance gene. First‐generation resistant weed beet exhibited traits likely counter‐selected. But such crop traits rapidly disappeared with backcrossing to weedy relatives: no biologically relevant difference was noted between resistant and susceptible near‐isogenic siblings in the various experiments. In the absence of resistance selection, our data indicate low chances for weed beet to evolve more competitive forms than present weed beet populations. However, they also suggest that there is no fitness cost limiting transgenes spread.
Armillaria root rot spreading into a natural woody ecosystem in South Africa
Authors: Coetzee M. P. A. , Musasira N. Y. , Roux J. , Roets F. , van der Merwe N. A. , Wingfield M. J.
Published: November 2017

Signs and symptoms of a disease similar to those of armillaria root rot have recently been observed on various native woody plants on the foothills of Table Mountain in South Africa, one of the most botanically diverse natural environments globally. This is of concern because the root rot fungus Armillaria mellea has previously been shown to be an alien pathogen of European origin in planted gardens in the City of Cape Town. An aim of this study was to identify the cause of the root rot disease on infected plants. Based on DNA‐sequence phylogeny, it was shown that isolates collected from at least 16 native tree and woody shrub species represented the non‐native A. mellea. Microsatellite markers were then used to determine the genetic diversity and population structure of the A. mellea isolates from Table Mountain and two planted gardens where the pathogen has previously been found. Population genetic analyses revealed low levels of gene diversity and no population differentiation amongst the three populations. The results provide the first firm evidence that A. mellea has escaped the planted environment and invaded a sensitive and ecologically important natural woody environment in South Africa. This is only the second definitive case of a non‐native tree pathogen invading a natural ecosystem in the country.
Reduced Numbers of Mature Medullary Thymic Epithelial Cells in SKG Mice
Authors: Engelmann R. , Biemelt A. , Johl A. , Kuthning D. , Müller‐Hilke B.
Published: November 2017

Attenuated T cell receptor (TCR) signalling contributes to the susceptibility for autoimmunity as shown via mutants of PTPN22 and Zap70 genes. We here set out to investigate the effect of an attenuated TCR signal on the composition of the thymic epithelial cell (TEC) compartment. To that extent, we combined flow cytometry and histology and compared the TEC subpopulations of Zap70 wild type with SKG mutant mice. We found an increased cortical TEC compartment in SKG thymi at the expense of reduced numbers of mature medullary TECs and a 4.8‐fold reduced medulla area. We also found reduced proportions of CD69+‐activated thymocytes among double‐negative, double‐positive and CD4−CD8+ single‐positive stages, reduced absolute numbers of single‐positive thymocytes, diminished expression of Lta and Ltb by CD4−CD8+ single‐positive thymocytes and a diminished expression of Ccl19, a target gene of the lymphotoxin‐b‐receptor. While the reduced thymocyte numbers together with the attenuated TCR signal explain the diminished expression of lymphotoxins, the latter is required for an AIRE‐independent expression of tissue‐restricted antigens as well as attracting positively selected thymocytes to the medulla. Our results describe altered TEC compartments in SKG mice that are likely to support the development of autoimmunity.
Evaluation of the Effect of Bariatric Surgery-Induced Weight Loss on Knee Gait and Cartilage Degeneration
Authors: Liukkonen Mimmi K. , Mononen Mika E. , Vartiainen Paavo , Kaukinen Päivi , Bragge Timo , Suomalainen Juha-Sampo , Malo Markus K. H. , Venesmaa Sari , Käkelä Pirjo , Pihlajamäki Jussi , Karjalainen Pasi A. , Arokoski Jari P. , Korhonen Rami K.
Published: November 2017

The objective of the study was to investigate the effects of bariatric surgery-induced weight loss on knee gait and cartilage degeneration in osteoarthritis (OA) by combining magnetic resonance imaging (MRI), gait analysis, finite element (FE) modeling, and cartilage degeneration algorithm. Gait analyses were performed for obese subjects before and one-year after the bariatric surgery. FE models were created before and after weight loss for those subjects who did not have severe tibio-femoral knee cartilage loss. Knee cartilage degenerations were predicted using an adaptive cartilage degeneration algorithm which is based on cumulative overloading of cartilage, leading to iteratively altered cartilage properties during OA. The average weight loss was 25.7±11.0 kg corresponding to a 9.2±3.9 kg/m2 decrease in body mass index (BMI). External knee rotation moment increased, and minimum knee flexion angle decreased significantly (p < 0.05) after weight loss. Moreover, weight loss decreased maximum cartilage degeneration by 5±23% and 13±11% on the medial and lateral tibial cartilage surfaces, respectively. Average degenerated volumes in the medial and lateral tibial cartilage decreased by 3±31% and 7±32%, respectively, after weight loss. However, increased degeneration levels could also be observed due to altered knee kinetics. The present results suggest that moderate weight loss changes knee kinetics and kinematics and can slow-down cartilage degeneration for certain patients. Simulation results also suggest that prediction of cartilage degeneration is subject-specific and highly depend on the altered gait loading, not just the patient's weight.
Effect of Prestress on Bridge–Vehicle Interactions
Authors: Zhong Hai , Yang Mijia
Published: November 2017

Prestress applied on bridges affects the dynamic interaction between bridges and vehicles traveling over them. In this paper, the prestressed bridge is modeled as a beam subjected to eccentric prestress force at the two ends, and a half-vehicle model with four degrees-of-freedom is used to represent the vehicle passing the bridge. A new bridge–vehicle interaction model considering the effect of prestress with eccentricity is developed through the principle of virtual work. The correctness and accuracy of the model are validated with literature results. Based on the developed model, numerical simulations have been conducted using Newmark's β method to study the effects of vehicle speed, eccentricity and amplitude of the prestress, and presence of multiple vehicles. It is shown that prestress has an important effect on the maximum vertical acceleration of vehicles, which may provide a good index for detecting the change of prestress. It is also interesting to find that the later-entering vehicle on the prestressed bridge will largely reduce the maximum vertical acceleration of the vehicle ahead of it.
Dynamical Graph Models of Aircraft Electrical, Thermal, and Turbomachinery Components
Authors: Williams Matthew A. , Koeln Justin P. , Pangborn Herschel C. , Alleyne Andrew G.
Published: November 2017

The current trend of electrification in modern aircraft has driven a need to design and control onboard power systems that are capable of meeting strict performance requirements while maximizing overall system efficiency. Model-based control provides the opportunity to meet the increased demands on system performance, but the development of a suitable model can be a difficult and time-consuming task. Due to the strong coupling between systems, control-oriented models should capture the underlying physical behavior regardless of energy domain or time-scale. This paper seeks to simplify the process of identifying a suitable control-oriented model by defining a scalable and broadly applicable approach to generating graph-based models of thermal, electrical, and turbomachinery aircraft components and systems. Subsequently, the process of assembling component graphs into a dynamical system graph that integrates multiple energy domains is shown. A sample electrical and thermal management system is used to demonstrate the capability of a graph model at matching the complex dynamics exhibited by nonlinear and empirically based simulation models.
Experimental Study on the Hydrodynamic Performance of Floating Pontoon Type Breakwater With Skirt Walls
Authors: Neelamani S. , Ljubic Josko
Published: November 2017

Floating breakwaters (FBWs) are widely used in moderate wave climatic conditions for coastal protection against erosion and for wave reduction around offshore loading terminals and open ocean construction sites. Literature shows that the width of a pontoon-type FBW is about 50% of the incident wavelength in order to achieve 50% wave height reduction at the lee side of the FBW. Hence, for a typical wavelength of 40 m, the width needed for pontoon FBW is about 20 m. Such an FBW may not be cost competitive. Is it possible to reduce the width of the pontoon FBW significantly by adding skirt walls (single, twin, triple, or five) at its keel. What will be the effect on mooring forces? In order to find solutions for these problems, experimental investigations were carried out on a typical pontoon-type FBW as well as pontoon with skirt walls. Both opaque and porous skirt walls were used. Wave transmission, reflection, and mooring forces, both on the sea side and lee side, were measured. It was found from this study that it is possible to reduce the width by 20 to 40% by introducing three or five skirt walls. However, introducing skirt walls increased the mooring forces by 10 to 30%. The results of this study are expected to be useful for cost-effective design of FBWs.
An Investigation on Creep and Creep-Rupture Behaviors of HMPE Ropes
Authors: Lian Yushun , Zheng Jinhai , Liu Haixiao
Published: November 2017

Creep tests of high modulus polyethylene (HMPE) samples are performed to obtain the corresponding creep and creep-rupture curves. The results show that the secondary creep stage is especially pronounced, and its creep rate is nearly constant. Based on this fact, the creep rate at the secondary stage has been utilized as the representative value of each case. Therefore, the similarity criterion of creep rate at secondary stage is proposed to analyze the corresponding relationship between engineering creep rate and that in laboratory tests. Besides, an empirical expression of HMPE yarns is proposed to account for the effects of both loading level and test temperature on the creep rate at the secondary stage. Moreover, an equation for calculating the creep lifetime of HMPE samples is derived and verified by test data. This study will help to improve the understanding of creep behaviors of HMPE ropes and provide a significant reference for the application of HMPE ropes in mooring engineering.
Reduced Order Modeling for Multistage Bladed Disks With Friction Contacts at the Flange Joint
Authors: Battiato Giuseppe , Firrone Christian M. , Berruti Teresa M. , Epureanu Bogdan I.
Published: November 2017

Most aircraft turbojet engines consist of multiple stages coupled by means of bolted flange joints which potentially represent source of nonlinearities due to friction phenomena. Methods aimed at predicting the forced response of multistage bladed disks have to take into account such nonlinear behavior and its effect in damping blades vibration. In this paper, a novel reduced order model (ROM) is proposed for studying nonlinear vibration due to contacts in multistage bladed disks. The methodology exploits the shape of the single-stage normal modes at the interstage boundary being mathematically described by spatial Fourier coefficients. Most of the Fourier coefficients represent the dominant kinematics in terms of the well-known nodal diameters (standard harmonics), while the others, which are detectable at the interstage boundary, correspond to new spatial small wavelength phenomena named as extra harmonics. The number of Fourier coefficients describing the displacement field at the interstage boundary only depends on the specific engine order (EO) excitation acting on the multistage system. This reduced set of coefficients allows the reconstruction of the physical relative displacement field at the interface between stages and, under the hypothesis of the single harmonic balance method (SHBM), the evaluation of the contact forces by employing the classic Jenkins contact element. The methodology is here applied to a simple multistage bladed disk and its performance is tested using as a benchmark the Craig–Bampton ROMs of each single stage.
Computational Fluid Dynamics Simulations of Regular and Irregular Waves Past a Horizontal Semi-Submerged Cylinder
Authors: Liu Shengnan , Ong Muk Chen , Obhrai Charlotte , Seng Sopheak
Published: November 2017

Two-dimensional (2D) numerical simulations have been performed to investigate both regular and irregular waves past a fixed horizontally semisubmerged circular cylinder. The 2D simulations are carried out by solving Navier–Stokes equations discretized by finite volume method. Volume of fluid (VOF) method is employed to capture the free surface in the numerical wave tank (NWT). Validation studies have been performed by comparing the numerical results of free surface waves past the cylinder with the published experimental and numerical data. The present numerical results are in good agreement with both the experimental and the other numerical results in terms of hydrodynamic forces and free surface elevation. Subsequently, the effects of the wave height and the wavelength on wave–structure interaction are investigated by conducting numerical simulations on the regular and the irregular waves past a semisubmerged cylinder at different wave heights and the wavelengths. The averaged and maximum vertical wave forces on the cylinder increase with the increasing wave height. The numerical results for the irregular waves are compared with those induced by the regular waves in terms of the maximum and averaged vertical wave forces. When the significant wave height and the spectral peak period of the irregular waves are equal to the wave height and the wave period of the regular waves, the maximum vertical wave force induced by the irregular waves is larger than that induced by the regular waves, meanwhile, the average vertical wave forces have the contrary relationship.
The Effects of Constant Kinetic Energy of Different Impacting Particles on Slurry Erosion Wear of AA 6063
Authors: Nandre Bhushan D. , Desale Girish R.
Published: November 2017

The present experimental study investigates the effect of constant kinetic energy on erosion wear of aluminum alloy 6063. Three different natural erodents (quartz, silicon carbide, and alumina) with different particle sizes are used to impact at 45 deg and 90 deg impact angles. For calculating the number of particles in the slurry pot, it is assumed that the solid particles are of spherical shape. The total numbers of impacting solid particles were kept constant by adjusting the solid concentration, velocity, and test duration. The scanning electron microscope (SEM) images of the three erodents show that the alumina particles have sharp edges with more angularity, and silicon carbide particles have subangular nature while quartz particles are blocky in shape. The mass loss per particle at 45 deg impact angle is observed higher than at normal impact angle. It may be due to the change in material removal mechanism with changing the impact angle. It is also found that the mass loss per particle from the target material having different particle size with constant kinetic energy remains constant for respective erodents. This indicates that the velocity exponent of impacting particles is around 2. The SEM images of eroded surfaces reveal the different mechanisms of material removal at 45 deg impact angle and at normal impact angle.
Methods for the Measurement of Non-Linear Damping and Frequency in Built-Up Structures
Authors: Goyder Hugh G. D. , Lancereau Damien P. T.
Published: November 2017

Two key properties of a vibrating structure are the frequencies at which it resonates and its ability to absorb energy. For a linear structure, these properties are characterised by the natural frequencies and the damping ratios. For nonlinear systems, such properties may not exist and equivalents must be sought. A method of measuring equivalent properties has been developed for nonlinear systems by examining the decaying vibration time history following excitation of the system.

In a first stage, the time history is filtered to separate out a frequency range of interest. In the second stage, which is the main concern of this paper, instantaneous values of natural frequencies and damping ratios are extracted from the decaying time history by means of a curve fitting process. The curve fitting involves finding four parameters two of which are the instantaneous natural frequency and damping ratio and two more which account for the amplitude and phase. The curve fitting is a minimisation process which is divided into two stages. For each minimisation step, the amplitude and phase are extracted first. It is shown that this may be done in a one-step process. Next the frequency and damping are determined. This is found to be a straightforward although more difficult process. The key to simplifying the problem is to recast the model in a favourable form that reduces the curve fitting process from one of finding four parameters to finding just two. The procedure is found to be robust and capable of detailed investigation.
A Numerical Study on Vibrations of a Roller Bearing With a Surface Crack in the Races
Authors: Liu Jing , Shi Zhifeng , Shao Yimin , Shi Boyang , Tian Zhongjian , Chen Jiahao
Published: November 2017

Vibrations of roller bearings will be affected when a surface crack is caused in the bearing system. Thus, it is very helpful to study relationships between the sizes of the surface crack and vibrations of the bearings for detecting and diagnosing the surface crack in the bearing systems. In this study, a dynamic finite element model for a roller bearing with a vertical or slant surface crack on its outer race is presented using an explicit dynamic finite element software package. All components of the roller bearing are formulated as elastic bodies in the finite element model, which can consider the elastic deformations in the bearing system. Effects of the depth and slope angle of the surface crack on the contact forces between the roller and races of the bearing are studied, as well as the vibrations of the bearing. The simulation results show that the explicit dynamic finite element analysis method can be applied for studying the vibration characteristics produced by a vertical or slant surface crack in roller bearings.
A Framework for Designing and Managing Flexibility and Real Options in Engineering Systems Based on Decision Rules
Authors: Xie Qihui , Cardin Michel-Alexandre
Published: November 2017

This paper introduces a framework to design and manage flexibility in engineering systems based on the concept of decision rules. A decision rule can be described as a heuristic triggering mechanism that is used to determine when it is appropriate to exercise flexibility in systems operations. The proposed framework differs from existing real options analysis (ROA) approaches used in a design and management setting by focusing on the practicability in the implementation phase of engineering systems. By incorporating decision rules in the design process, this framework not only helps generate better performing designs, it also provides intuitive guidance for decision makers (DMs) to manage the system in operations. The proposed framework is applied as demonstration to the design and management of an anaerobic digestion (AD) waste-to-energy (WTE) plant. It demonstrates significant lifecycle performance improvement as compared to a standard design analysis. A comparison with existing ROA approaches shows that another advantage of the proposed framework is the ability to analyze systems facing multiple uncertainty sources and relying on multiple flexibility strategies as a way to improve expected lifecycle performance.
Calculation of Time-Varying Mesh Stiffness Affected by Load Based on FEM
Authors: Cheng Qian , Shao Yimin , Liu Jing , Yin Lei , Du Minggang , Yang Yang
Published: November 2017

Time-varying mesh stiffness (TVMS) is a key component of gear transmission system for gear dynamic response. When the machine starts working, stop working or goes into an unstable working condition, the load will be varying. In order to investigate the impact of different loads on TVMS, a numerical method based on FEM is proposed in this paper to study the effect of TVMS. The dynamic mesh forces and dynamic displacements along the action line direction at each mesh point are extracted. The calculated TVMS is validated by comprising with the TVMS calculated by the analytical method (AM). The results show that TVMS increases with the rise of input moment which can be intruded in gear dynamic behavior study under different load condition.
A Numerical Approach to the Calculation of the Surface Temperature Distribution of Worm Gears
Authors: Roth Philipp , Sigmund Werner , Born Sebastian , Kadach Daniel , Stahl Karsten
Published: November 2017

This paper presents a numerical approach to calculate the distribution of the surface temperature of worm gears, which is needed to determine the scuffing load capacity. The simulation model used for the heat transport as well as its boundary conditions are explained. Exemplary results for various operating conditions and temperature courses over time are presented. A comparison of the simulation model with another model from literature reveals deviating results. It is shown that the deviations can be attributed to limitations of the model from literature. These limitations do not apply to the numerical simulation model that is presented in this paper.
Optimal Rib Layout Design of Gearbox for the Reduction of Radiated Noise
Authors: Liu G. , Wang J. P. , Chang S.
Published: November 2017

In this paper, a method to determine the optimal rib layout of gearbox for the noise reduction is proposed based on acoustic contribution analysis and topology optimization. Firstly, the radiated noise is simulated using the finite element method (FEM) and boundary element method (BEM). The field point with maximum sound pressure is taken as the objective field point. Secondly, the surface of gearbox is divided into different regions and the region with maximum acoustic contribution to the sound pressure on the objective field point is found by acoustic transfer vector analysis and acoustic contribution analysis. Thirdly, the topology optimization model is established to reduce the velocities on the region with maximum acoustic contribution. Lastly, the topology optimization model is solved using the SIMP method and the ribs can be arranged according to the results of topology optimization. The simulation results show that the sound pressure on objective field point is reduced remarkably by using this method.
Modeling and Design Enhancement of Differential-Frequency Microgyroscopes Made of Nanocrystalline Material
Authors: Ghommem Mehdi , Abdelkefi Abdessattar
Published: November 2017

The performance of a microgyroscope consisting of a microbeam made of nanocrystalline silicon connected to a rigid proof mass and subjected to electric actuation is numerically investigated. The operating principle is based on the transfer of mechanical energy among two vibration modes (drive and sense) via the Coriolis effect. The onset of the base rotation is observed to split the common natural frequency of the two bending modes along drive and sense directions into a pair of closely-spaced natural frequencies. The difference between this pair of frequencies is considered as the output parameter detecting the rotation rate. We follow an analytical approach to obtain closed-form solutions of the static and dynamic responses of the microsystem. Furthermore, we perform a sensitivity analysis of the output parameter of the present microgyroscope to the rotation rate when varying the material properties of the microbeam and the electric actuation.
Well-Posedness of Fractional Differential Equations
Authors: Li Changpin , Ma Li
Published: November 2017

Generally speaking, definite conditions of fractional differential equations with Riemann-Liouville, Riesz or Hadamard fractional derivatives are quite different from those of classic differential equations. In this paper, we propose the well-posed conditions for fractional differential equation involving right Riemann-Liouville, Riesz and Hadamard fractional derivatives.
Analysis of Nonlinear Dynamics of a Rotor-Active Magnetic Bearing System With 16-Pole Legs
Authors: Wu Ruiqin , Zhang Wei , Yao Ming Hui
Published: November 2017

In this paper, we use the asymptotic perturbation method to analyze the nonlinear dynamics of a rotor-active magnetic bearing (AMB) system with 16-pole legs. The motion governing equation is derived by using classical Newton law. The resulting dimensionless equation of motion for the system is expressed as a two-degree-of-freedom system including the parametric excitation, quadratic and cubic nonlinearities. The asymptotic perturbation method is used to obtain the averaged equation when the primary resonance and 1/2 sub-harmonic resonance are taken into consideration. From the averaged equations obtained, numerical simulations are presented to investigate the modulation of vibration amplitudes of the rotor-AMB system. Based on a specific set of parameters, it is found that there exist the periodic, quasi-periodic and chaotic motions in the modulated amplitude of the rotor in the system.
Generalized Disturbance Observer Synthesis Using a Two-Stage Heuristic Algorithm
Authors: Xiang Guofei , Su Jianbo
Published: November 2017

Disturbance observer (DOB) based control has been widely applied in industries due to its easy usage but powerful disturbance rejection ability. However, the existence of innate structure constraint, namely the inverse of the nominal plant, prevents its implementation on more general class of systems, such as non-minimum phase plants, MIMO systems etc.. Furthermore, additional limitations exerted on Q-filter design, i.e., unity steady state gain and low-pass nature, which narrow down its solution space largely and prevent from achieving optimal performance even if it exists. In this paper, we present a novel DOB architecture, named generalized disturbance observer (G-DOB), with the help of nontraditional use of the celebrated Youla parametrization of two degree-of-freedom controller. Rigorous analyses show that the novel G-DOB not only inherits all the merits of the conventional one, but also alleviates the limitations stated before partially. By some appropriate system manipulation, the synthesis of Q-filter has been converted to the design of reduced-order controller. Thus, a heuristic two-stage algorithm has been developed with the help of Kalman-Yakubovich-Popov (KYP) lemma: firstly design a full information controller for the augmented system and then compute a reduced-order controller. Numerical examples are presented to demonstrate the effectiveness of the proposed G-DOB structure and design algorithm.
On the ADRC of Non-Differentially Flat, Underactuated, Nonlinear Systems: An Experimental Case Study
Authors: Sira-Ramírez H. , Zurita-Bustamante E. W. , Hernández-Flores E.
Published: November 2017

In this article, the output reference trajectory tracking control of a non-differentially flat, underactuated, system is approached from the perspective of Active Disturbance Rejection Control (ADRC) including a suitable Extended State Observer (ESO). The class of underactuated systems, which are non-differentially flat, constitutes the most challenging area for testing the effectiveness of robust feedback control algorithms, specially under output trajectory tracking requirements. The problem, however, is substantially alleviated and feasibly approached provided the tangent linearization of the system is found to be controllable around an arbitrary equilibrium point. The flatness of the tangent system is taken advantage of for the design of an observer-based feedback controller taking the tangent system operation substantially far from the operating point. The ADRC scheme robustly takes efficient care of the excited (endogenous) nonlinearities, which were neglected in the linearization process, as well as any other external (exogenous) disturbances. Here, we take the gantry crane and its closely associated system: the inverted pendulum on a cart, as working laboratory examples to illustrate the effectiveness of the proposed approach.
Nonlinear Dynamics of FGM Conical Panel With Initial Imperfection in Thermal Environment
Authors: Yao Ming Hui , Niu Yan , Zhang Wei
Published: November 2017

In this paper, the nonlinear dynamics of a simply supported functionally graded materials (FGM) conical panel with different forms of initial imperfections is investigated. The conical panel is subjected to the simple harmonic excitation along the radial direction and the parametric excitation in the meridian direction. The small initial geometric imperfection of the conical panel is expressed by the form of the Cosine functions. According to a power-law distribution, the effective material properties are assumed to be graded along the thickness direction. Based on the first-order shear deformation theory and von Karman type nonlinear geometric relationship, the nonlinear equations of motion are established by using the Hamilton principle. The nonlinear partial differential governing equations are truncated by Galerkin’s method to obtain the ordinary differential equations along the radial displacement. The effects of imperfection types, half-wave numbers and amplitudes on the dynamic behaviors are studied by numerical simulation. Maximum Lyapunov exponents, bifurcation diagrams, time histories and phase portraits are obtained to show the dynamic response.