bluuebunny/crossref_metadata_2025 huggingface dataset:
Elevated carbon dioxide and warming impact silicon and phenolic‐based defences differently in native and exotic grasses
Authors: Johnson Scott N. , Hartley Susan E.
Published: November 2017

Global climate change may increase invasions of exotic plant species by directly promoting the success of invasive/exotic species or by reducing the competitive abilities of native species. Changes in plant chemistry, leading to altered susceptibility to stress, could mediate these effects. Grasses are hyper‐accumulators of silicon, which play a crucial function in the alleviation of diverse biotic and abiotic stresses. It is unknown how predicted increases in atmospheric carbon dioxide (CO2) and air temperature affect silicon accumulation in grasses, especially in relation to primary and secondary metabolites. We tested how elevated CO2(eCO2) (+240 ppm) and temperature (eT) (+4°C) affected chemical composition (silicon, phenolics, carbon and nitrogen) and plant growth in eight grass species, either native or exotic to Australia. eCO2increased phenolic concentrations by 11%, but caused silicon accumulation to decline by 12%. Moreover, declines in silicon occurred mainly in native species (−19%), but remained largely unchanged in exotic species. Conversely, eT increased silicon accumulation in native species (+19%) but decreased silicon accumulation in exotic species (−10%). Silicon and phenolic concentrations were negatively correlated with each other, potentially reflecting a defensive trade‐off. Moreover, both defences were negatively correlated with plant mass, compatible with a growth‐defence trade‐off. Grasses responded in a species‐specific manner, suggesting that the relative susceptibility of different species may differ under future climates compared to current species rankings of resource quality. For example, the nativeMicrolaena stipoideswas less well defended under eCO2in terms of both phenolics and silicon, and thus could suffer greater vulnerability to herbivores. To our knowledge, this is the first demonstration of the impacts of eCO2and eT on silicon accumulation in grasses. We speculate that the greater plasticity in silicon uptake shown by Australian native grasses may be partly a consequence of evolving in a low nutrient and seasonally arid environment.
Electoral geography: From mapping votes to representing power
Authors: Forest Benjamin
Published: November 2017

In some ways, electoral geography has never been more popular. From the detailed, online maps of the Brexit vote to discussions of the electoral college versus the popular vote in the 2016 Trump–Clinton U.S. presidential contest, the relationships among geography, voting, and political power have seldom been more visible. The popularity of electoral geography in social and news media, however, does not necessarily reflect its presence in scholarly discussions, and indeed, in some ways, the former has replaced the latter. Digital technology and the burgeoning availability of electronic data mean that it is easier than ever to create maps of votes, often in near real time. Yet the academic field of electoral geography encompasses more than just mapping votes, including the study of election campaigns, political parties, electoral systems, and gerrymandering. The 3 major approaches are the geography of voting (mapping and visualizing votes), geographic influences on voting (the effect of place on political preferences and behavior), and the geography of representation (the analysis of electoral systems). Indeed, the structure of the electoral system, including gerrymandering, is often the key to understanding how political and racial/ethnic minorities can (or cannot) wield power and influence. This article examines each approach after a brief review of the historical origins of the subfield.
Factors predicting quality of work life among nurses in tertiary‐level hospitals, Bangladesh
Authors: Akter N. , Akkadechanunt T. , Chontawan R. , Klunklin A.
Published: November 2017

Aim

This study examined the level of quality of work life and predictability of years of education, monthly income, years of experience, job stress, organizational commitment and work environment on quality of work life among nurses in tertiary‐level hospitals in the People's Republic of Bangladesh.

Background

There is an acute shortage of nurses worldwide including Bangladesh. Quality of work life is important for quality of patient care and nurse retention. Nurses in Bangladesh are fighting to provide quality care for emerging health problems for the achievement of sustainable development goals.

Methods

We collected data from 288 randomly selected registered nurses, from six tertiary‐level hospitals. All nurses were requested to fill questionnaire consisted of Demographic Data Sheet, Quality of Nursing Work Life Survey, Expanded Nursing Stress Scale, Questionnaire of Organizational Commitment and Practice Environment Scale of the Nursing Work Index. Data were analysed by descriptive statistics and multiple regression.

Results

The quality of work life as perceived by nurses in Bangladesh was at moderate level. Monthly income was found as the best predictor followed by work environment, organizational commitment and job stress.

Discussion

A higher monthly income helps nurses to fulfil their personal needs; positive work environment helps to provide quality care to the patients.

Limitation

Quality of work life and predictors measured by self‐report only may not reflect the original picture of the quality of work life among nurses.

Conclusion and policy implications

Findings provide information for nursing and health policymakers to develop policies to improve quality of work life among nurses that can contribute to quality of nursing care. This includes the working environment, commitment to the organization and measures to reduce job stress.
Similarity and entropy measures for hesitant fuzzy sets
Authors: Hu Junhua , Yang Yan , Zhang Xiaolong , Chen Xiaohong
Published: November 2017

Hesitant fuzzy sets (HFSs) are beneficial tools for expressing the hesitancy of decision makers (DMs) to access alternatives in daily life, thereby enabling the membership of an element to a set that is represented by several possible values. This study proposes an interval bound footprint (IBF), which describes the fluctuation range of the values of hesitant fuzzy elements (HFEs) arranged in order. In addition, a few similarity and entropy measures for HFSs are deduced. First, the interval bound footprint, upper bound footprint, and lower bound footprint for HFEs are defined and their corresponding properties are discussed. Subsequently, several similarity and entropy measures for HFSs are presented based on IBF. Lastly, a hesitant fuzzy multi‐criteria decision‐making method based on the proposed similarity and entropy measures is introduced. We use a numerical example to discuss the differences among the proposed similarity measures and the applicable environment based on the risk preferences of the different DMs.
The importance of ethical aspects when implementing eHealth services in healthcare: A discussion paper
Authors: Skär Lisa , Söderberg Siv
Published: November 2017

Aim

The aim of this paper was to discuss the importance of ethical aspects when implementing eHealth services in health care.

Background

Challenges in healthcare today include a growing older population and, as a consequence, an increased need for healthcare services. One possible solution is the use of eHealth services.

Design

Discussion paper.

Data sources

Research literature published from 2000–2017 in CINAHL, PubMed and Scopus.

Implications for nursing

Implementing eHealth services in health care involves ethical challenges where different technologies can solve different problems in different ways. eHealth services should therefore be developed and implemented based on the patient's specific needs and conditions for use and in accordance with the healthcare professionals' presumption to provide high‐quality care.

Conclusion

To preserve patients' integrity, dignity and autonomy, healthcare professionals must include ethical aspects when implementing and using eHealth services in health care. Healthcare professionals have to take responsibility for the eHealth services introduced, explaining why and how they are implemented based on a person‐centred approach. More knowledge is needed about ethical aspects when implementing eHealth services to improve the quality of care.
Instruments to assess patient comfort during hospitalization: A psychometric review
Authors: Lorente Sonia , Losilla Josep‐Maria , Vives Jaume
Published: November 2017

Aim

To analyse the psychometric properties and the utility of instruments used to measure patient comfort, physical, social, psychospiritual and/or environmental, during hospitalization.

Background

There are no systematic reviews nor psychometric reviews of instruments used to measure comfort, which is considered an indicator of quality in health care associated with quicker discharges, increased patient satisfaction and better cost–benefit ratios for the institution.

Design

Psychometric review.

Data sources

MEDLINE, CINAHL, PsycINFO, Web of Knowledge, ProQuest Thesis&Dissertations, Google.

Review methods

We limited our search to studies published between 1990‐2015. The psychometric analysis was performed using the COnsensus‐based Standards for the selection of health status Measurement INstruments (COSMIN), along with the Quality Criteria for Measurement Properties. The utility of the instruments was assessed according to their cost‐efficiency, acceptability and educational impact. Protocol registration in PROSPERO, CRD42016036290.

Results

Instruments reviewed showed moderate methodological quality and their utility was poorly reported. Thus, we cannot recommend any questionnaire without reservations, but the Comfort Scale, the General Comfort Questionnaire and their adaptations in adults and older patients, the Psychosocial Comfort Scale and the Incomfort des Patients de Reanimation are the most recommendable instruments to measure comfort.

Conclusions

The methodology of the studies should be more rigorous and authors should adequately report the utility of instruments. This review provides a strategy to select the most suitable instrument to assess patient comfort according to their psychometric properties and utility, which is crucial for nurses, clinicians, researchers and institutions.
Risk factors for psychological and psychosomatic symptoms among children with malignancies
Authors: Maeda Kenichi , Hasegawa Daisuke , Urayama Kevin Y , Tsujimoto Shinichi , Azami Yuriko , Ozawa Miwa , Manabe Atsushi
Published: November 2017

Aim

With increasing survival rates in paediatric malignancies, the quality‐of‐life of children during hospitalisation should be given more attention. We aimed to identify factors associated with psychological and psychosomatic symptoms (PPS) that required medication among children hospitalised for treatment of malignancies.

Methods

We retrospectively analysed data of 190 patients aged 2–18 years old. They were diagnosed with malignant diseases and admitted for treatment at St. Luke's International Hospital between 2003 and 2013. Patients were considered as having PPS if they were prescribed psychotropic agents during hospitalisation.

Results

Of the 190 patients, 56 (30%) were prescribed psychotropic agents for PPS. Types of PPS included insomnia in 21 (38%), anxiety in 11 (20%), and others conditions (psychogenetic nausea, agitation, delirium, depression). The most prescribed psychotropic agents were etizolam for 34 cases (61%), followed by diazepam and risperidone. The multivariable analyses confirmed statistically significant independent associations for haematopoietic stem cell transplantation (HSCT) (odds ratio (OR), 5.21; 95% confidence interval (CI), 1.77–15.35), older age (12–18 years vs. 2–5 years, OR, 3.74; 95% CI, 1.04–10.00), and opioid use (OR, 7.15; 95% CI, 2.36–21.69).

Conclusions

Older age at admission, undergoing HSCT, and those given opioids were found to be risk factors for PPS among children with malignancies. Appropriate preventive measures against PPS may be warranted for patients with these risk factors.
Differentiation between cystic biliary atresia and choledochal cyst: A retrospective analysis
Authors: Tang Jue , Zhang Dan , Liu Wei , Zeng Ji‐Xiao , Yu Jia‐Kang , Gao Yi
Published: November 2017

Aim

Cystic biliary atresia (CBA) can be easily misdiagnosed as choledochal cyst (CC). Some patients have already progressed to severe liver fibrosis and missed the optimal surgical time, when the differential diagnosis is made. We aim to determine the differentiation between CBA and CC, and to validate the value of aspartate aminotransferase‐to‐platelet ratio index (APRI) in the assessment of liver fibrosis and prediction of post‐operative outcome for infants with biliary cystic malformations (BCMs).

Methods

Clinical data of children (categorised into CBA and CC groups) with BCMs were analysed retrospectively. Biochemical indicators together with B‐ultrasound examinations and the degree of liver fibrosis were analysed, and those with statistical difference between the two groups were selected for diagnostic receiver operating characteristic curve analysis.

Results

The parameter that showed the highest accuracy with a significant diagnostic performance for differentiating CBA from CC was cyst size. Liver assessment at operation was categorised into mild fibrosis and moderate‐to‐severe fibrosis. The APRI values were much lower in the mild fibrosis groups than in the moderate‐to‐severe fibrosis group (0.4 ± 0.2 vs. 1.4 ± 0.8, P < 0.001). A cut‐off value of 0.96 (area under the curve 0.92, P < 0.001) showed a sensitivity of 81.3% and a specificity of 100% for moderate‐to‐severe fibrosis. Lower APRI value was correlated with short‐term post‐operative bilirubin clearance.

Conclusion

There is still certain difficulty in the early identification of CBA and CC clinically. Liver fibrosis could occur as early as infantile period in both CBA and CC. In infants with BCMs, APRI can be used as a non‐invasive method to detect liver fibrosis in early stages.
Minimally invasive technique for coxofemoral luxation stabilisation using transarticular toggle system: a cadaveric study
Authors: Segal U. , Shani J. , Joseph R.
Published: November 2017

Objective

To present a novel, semi‐closed, surgical technique for coxofemoral luxation stabilisation using a transarticular toggle rod.

Study Design

Cadaveric study.

Materials and Methods

Craniodorsal luxation was generated by transecting the ligamentum teres in 12 coxofemoral joints and was then reduced using a closed technique. Anteversion and inclination angles were measured using fluoroscopic projections. An arthroscope was inserted through a bone tunnel drilled from the third trochanter through the femoral neck. Following retraction of the arthroscope, a hole was drilled through the acetabular fossa via the femoral bone tunnel. A standard Arthrex® TightRope toggle button was pushed through the femoral bone tunnel into the acetabular fossa hole and tied over the oval metallic button above the third trochanter site. The exit point of the drill hole over the femoral head and that in the acetabular fossa were evaluated by surgical exposure of the coxofemoral articular surfaces.

Results

The TightRope entrance point into the acetabular fossa was accurate in all joints, with a mean distance from the acetabular fossa centre of 0·06 ±0·1 mm. The measured distance of the TightRope exit point from the femoral head to the fovea capitis was 2·04 ±1·7 mm. Femoral head cartilage damage was detected in nine of 12 joints.

Conclusion and Clinical Relevance

Closed reduction and stabilisation of coxofemoral luxations can be achieved using this minimally invasive technique. Refinements to the technique may be needed for its application in clinical cases due to relative high incidence of femoral head cartilage damage.
Expression of tomato prosystemin gene in Arabidopsis reveals systemic translocation of its mRNA and confers necrotrophic fungal resistance
Authors: Zhang Haiyan , Yu Pengli , Zhao Jiuhai , Jiang Hongling , Wang Haiyang , Zhu Yingfang , Botella Miguel A. , Šamaj Jozef , Li Chuanyou , Lin Jinxing
Published: November 2017

Systemin (SYS), an octadecapeptide hormone processed from a 200‐amino‐acid precursor (prosystemin, PS), plays a central role in the systemic activation of defense genes in tomato in response to herbivore and pathogen attacks. However, whether PS mRNA is transferable and its role in systemic defense responses remain unknown.

We created the transgenic tomato PS gene tagged with the green fluorescent protein (PS‐GFP) using a shoot‐ or root‐specific promoter, and the constitutive 35S promoter in Arabidopsis. Subcellular localization of PS‐/SYS‐GFP was observed using confocal laser scanning microscopy and gene transcripts were determined using quantitative real‐time PCR.

In Arabidopsis, PS protein can be processed and SYS is secreted. Shoot‐/root‐specific expression of PS‐GFP in Arabidopsis, and grafting experiments, revealed that the PS mRNA moves in a bi‐directional manner. We also found that ectopic expression of PS improves Arabidopsis resistance to the necrotrophic fungus Botrytis cinerea, consistent with substantial upregulation of the transcript levels of specific pathogen‐responsive genes.

Our results provide novel insights into the multifaceted mechanism of SYS signaling transport and its potential application in genetic engineering for increasing pathogen resistance across diverse plant families.
Designing Public Participation: Managing Problem Settings and Social Equity
Authors: Clark Jill K.
Published: November 2017

Researchers suggest that inequity and disparities in public participation in the policy‐making process will go hand in hand unless public managers and community leaders are attentive to these concerns when they are designing participation opportunities. Previous research has considered how the design of participatory opportunities can address inequity, but it has provided few insights into what is behind design choices. This article provides a theoretical framework that links public managers' and community leaders' perspectives on their own political efficacy and sources of their efficacy, yielding four types of “designers.” The research hypothesizes that these types have different narratives of social equity in participation that affect their design choices. Data from more than 100 public managers and community leaders provide preliminary support for these relationships. Findings suggest that inequitable public participation will persist unless designers consider what is behind their choices, focusing first on understanding the problem setting, or their narrative of equity in public participation.
The effects of off‐farm work on fertilizer and pesticide expenditures in China
Authors: Ma Wanglin , Abdulai Awudu , Ma Chunbo
Published: November 2017

This study examines the effects of participation in off‐farm work on farm expenditures on fertilizer and pesticide, using farm household survey data from China. Simple mean value comparisons reveal no statistically significant differences in fertilizer and pesticide expenditures between off‐farm work participants and nonparticipants. However, econometric estimation with a treatment effects model shows a negative selection bias. After controlling for this bias, the empirical results show that participation in off‐farm work exerts a positive and statistically significant impact on fertilizer and pesticide expenditures. Our findings generally suggest that the income effect of off‐farm work stimulates agricultural production by increasing investments in productivity‐enhancing inputs.
Improving the SNA Treatment of Multinational Enterprises
Authors: Rassier Dylan G.
Published: November 2017

Core measures in the System of National Accounts (SNA) may reflect distortions based on the treatment of multinational enterprises (MNEs) under the residence concept, which is effectively a legal concept rather than an economic concept for special purpose entities that lack production. This paper suggests an improvement to the SNA treatment of MNEs by proposing an SNA framework that offers a dual presentation of measures on operating entities and measures on special purpose entities. A dual presentation adds information to better understand the role of MNEs and special purpose entities in national accounts. Nevertheless, the proposal also yields a meaningful departure from current SNA recommendations and current practice by statistical compilers, which requires careful consideration of practical matters before implementation is feasible.
Inequality: Measurement, Trends, Impacts and Policies
Authors: Addison Tony , Pirttilä Jukka , Tarp Finn
Published: November 2017

Many low‐ and middle‐income countries are achieving good rates of economic growth, while high inequality remains a priority concern. Some countries meanwhile have low growth, high inequality, and pervasive poverty—often linked to their fragility. There is now active debate on how countries should set themselves goals for achieving both absolute poverty reduction and lower inequality. But policy action needs to be better served by analysis and data.
Markups and Concentration in South African Manufacturing Sectors: An Analysis with Administrative Data
Authors: Fedderke Johannes , Obikili Nonso , Viegi Nicola
Published: November 2017

This paper uses newly available firm‐level tax data to evaluate the market structure in South African manufacturing sectors in the period 2010‐2012. To describe the market structure, we compute markups for South African manufacturing firms and concentration indexes for 4‐digit manufacturing sectors. We find both significant markups and significant concentration across most sectors. We compare computed markups and concentration with early estimates in South Africa and with other international benchmark countries. We then examine the market structure based on the concentration, firms size and entry and exit dynamics to rule out some potential explanations for relatively high markups. We find that the relationships are not monotonic and point to the importance of specific barriers to entry in explaining the relationship between these three characteristics.
Unemployment in Africa: A Fractional Integration Approach
Authors: Caporale Guglielmo Maria , Gil‐Alana Luis Alberiko
Published: November 2017

This paper estimates long‐memory models to analyse the stochastic behaviour of unemployment in eleven African countries (Botswana, Ethiopia, Ghana, Kenya, Malawi, Mauritius, Nigeria, Senegal, South Africa, Tanzania and Zambia) from the 1960s until 2010. The empirical results provide very strong evidence of lack of mean reversion in all series under examination. This suggests that hysteresis models are the most relevant for the African experience (not surprisingly, given the rigidities in their labour markets). Therefore in such countries shocks hitting the unemployment series will have permanent effects, and policy makers should take appropriate action to reverse the effects of negative shocks.
Composite Estimation for Single‐Index Models with Responses Subject to Detection Limits
Authors: Tang Yanlin , Wang Huixia Judy , Liang Hua
Published: November 2017

We propose a semiparametric estimator for single‐index models with censored responses due to detection limits. In the presence of left censoring, the mean function cannot be identified without any parametric distributional assumptions, but the quantile function is still identifiable at upper quantile levels. To avoid parametric distributional assumption, we propose to fit censored quantile regression and combine information across quantile levels to estimate the unknown smooth link function and the index parameter. Under some regularity conditions, we show that the estimated link function achieves the non‐parametric optimal convergence rate, and the estimated index parameter is asymptotically normal. The simulation study shows that the proposed estimator is competitive with the omniscient least squares estimator based on the latent uncensored responses for data with normal errors but much more efficient for heavy‐tailed data under light and moderate censoring. The practical value of the proposed method is demonstrated through the analysis of a human immunodeficiency virus antibody data set.
The biology and polymer physics underlying large‐scale chromosome organization
Authors: Sazer Shelley , Schiessel Helmut
Published: November 2017

Chromosome large‐scale organization is a beautiful example of the interplay between physics and biology. DNA molecules are polymers and thus belong to the class of molecules for which physicists have developed models and formulated testable hypotheses to understand their arrangement and dynamic properties in solution, based on the principles of polymer physics. Biologists documented and discovered the biochemical basis for the structure, function and dynamic spatial organization of chromosomes in cells. The underlying principles of chromosome organization have recently been revealed in unprecedented detail using high‐resolution chromosome capture technology that can simultaneously detect chromosome contact sites throughout the genome. These independent lines of investigation have now converged on a model in which DNA loops, generated by the loop extrusion mechanism, are the basic organizational and functional units of the chromosome.
Does noncontact low‐frequency ultrasound therapy contribute to wound healing at the molecular level?
Authors: Wiegand Cornelia , Bittenger Kyle , Galiano Robert D. , Driver Vickie R. , Gibbons Gary W.
Published: November 2017

Noncontact low‐frequency ultrasound (NLFU) is used to treat various types of chronic wounds including venous, diabetic, and pressure ulcers. The objective for this substudy of the IN BALANCE RCT VLU trial was to characterize and compare the NLFU treatment group and patients receiving standard of care (SOC) with respect to the effect of the assigned study treatment on content/quantity of inflammatory cytokines and fibrinogen as well as bacteria. Higher mean wound area reduction was observed in the NLFU treatment group (67.0%) compared to the SOC group (41.6%, p < 0.05). Hypertension, diabetes type II, coronary artery disease, and anemia were identified as the most common comorbidities of the Chronic venous leg ulcer (CVLU) patients included in the study. Pseudomonas, Corynebacterium, and unclassified Enterobacteriaceae were dominant in the highest number of samples. Anaerococcus, Peptoniphilus, and Finegoldia, had the highest median proportion in the samples overall. Peptoniphilus abundance decreased more in the NLFU treatment group relative to SOC; similar trends were observed for Anaerococcus and Finegoldia. Progression of mediators like TNF‐alpha, IL‐1beta, IL‐6, IL‐8, and IL‐10 as well as PF4, TGF‐beta, and fibrinogen was monitored and trends for several of the mediators were identified. Fibrinogen amounts were significantly reduced over time in the NLFU treatment group (p < 0.05). IL‐8 levels declined in wound fluid from NLFU responders as well as SOC responders. Bacterial load (total bacterial abundance) determined local parameters of ulcer inflammation. If a bioburden of ≥ 10E5 was found compared to < 10E5, levels of IL‐1beta, IL‐8, and TNF‐alpha were significantly higher. In conclusion, NLFU treatment is an effective adjuvant tool for CVLU therapy. This study demonstrates that it improves wound healing by equally inhibiting abundant levels of pro‐inflammatory cytokines as well as by reducing the overall bacterial burden.
Intrauterine growth restriction results in persistent vascular mismatch in adulthood
Authors: Kuo Anderson H. , Li Cun , Huber Hillary F. , Clarke Geoffrey D. , Nathanielsz Peter W.
Published: November 2017

Key points

Intrauterine growth restriction (IUGR) increases offspring risk of chronic diseases later in life, including cardiovascular dysfunction.

Our prior studies suggest biventricular cardiac dysfunction and vascular impairment in baboons who were IUGR at birth because of moderate maternal nutrient reduction.

The current study reveals changes in artery sizes, distensibility, and blood flow pattern in young adult IUGR baboons, which may contribute to cardiac stress.

The pattern of abnormality observed suggests that vascular redistribution seen with IUGR in fetal life may continue into adulthood.

Maternal nutrient reduction induces intrauterine growth restriction (IUGR), increasing risks of chronic diseases later in life, including cardiovascular dysfunction. Using ultrasound, we determined regional blood flow, blood vessel sizes, and distensibility in IUGR baboons (8 males, 8 females, 8.8 years, similar to 35 human years) and controls (12 males, 12 females, 9.5 years). The measured blood vessels were larger in size in the males compared to females before but not after normalization to body surface area. Smaller IUGR normalized blood vessel sizes were observed in the femoral and external iliac arteries but not the brachial or common carotid arteries and not correlated significantly with birth weight. Mild decrease in distensibility in the IUGR group was seen in the iliac but not the carotid arteries without between‐sex differences. In IUGR baboons there was increased carotid arterial blood flow velocity during late systole and diastole. Overall, our findings support the conclusion that region specific vascular and haemodynamic changes occur with IUGR, which may contribute to the occurrence of later life cardiac dysfunction. The pattern of alteration observed suggests vascular redistribution efforts in response to challenges in the perinatal period may persist into adulthood. Further studies are needed to determine the life course progression of these changes.
Heat Transfer of Springs in Oblique Crossflows
Authors: Biggs Daniel B. , Churchill Christopher B. , Shaw John A.
Published: November 2017

An experimental program is presented of heated tension springs in an external crossflow over a range of laminar Reynolds numbers, spring stretch ratios, and angles of attack. Extensive measurements of the forced convection heat transfer of helical wire within a wind tunnel reveal an interesting nonmonotonic dependence on angle of attack. Computational fluid dynamics (CFD) simulations, showing good agreement with the experimental data, are used to explore the behavior and gain a better understanding of the observed trends. A dimensionless correlation is developed that well captures the experimental and CFD data and can be used as an efficient computational tool in broader applications.
A New Transient High Heat Flux Convection Calibration Facility for Heat Transfer Gauges in High Enthalpy Flows
Authors: Lubbock R. J. , Luque S. , Rosic B. R.
Published: November 2017

This paper presents a novel transient method for calibrating heat transfer gauges for convective wall heat flux measurements in high enthalpy flows. The new method relies on the transient heating of sensor substrates under rapid exposure to a hot flow in order to obtain the necessary reference heat flux. Compared to previous calibration facilities, the new facility is simple, inexpensive, easy to adapt for different flow configurations and sensor geometries, and quick to run across a wide range of conditions. In this paper, the design of the new calibration facility is described and the transient calibration method explained. The method is demonstrated by calibrating a Gardon gauge at convective heat transfer coefficients between 300 and 600 W/m2 K. Typical facility data and calibration results are presented in terms of voltage-heat flux sensitivity and calibration correction ratio. These results are shown to agree with theoretical estimates within the estimated calibration uncertainty.
The Coordinated Immersion and Variance Control of Power Systems With Excitation and Steam-Valve
Authors: Li Shengtao , Liu Xiaomei , Liu Xiaoping
Published: November 2017

Transient stability is the key problem for reliable and secure planning under the new deregulated market conditions. By using immersion and invariance (I&I) method, a nonlinear coordinated generator excitation and steam-valve controller is designed to improve transient stability of power systems. The proposed coordinated I&I controller can assure power angle stability, voltage, and frequency regulations, when a large disturbance occurs on the transmission line or a small perturbation to mechanical power. Compared with the Lyapunov method, the proposed method does not need to construct a Lyapunov energy function. Some numerical simulations are used to validate the proposed controller. Simulation results show that the nonlinear coordinated I&I controller has better control performance than the existing coordinated passivation controller (CPC).
Improved In-Line Vortex-Induced Vibrations Prediction for Combined In-Line and Cross-Flow Vortex-Induced Vibrations Responses
Authors: Yin Decao , Passano Elizabeth , Larsen Carl M.
Published: November 2017

Slender marine structures are subjected to ocean currents, which can cause vortex-induced vibrations (VIV). Accumulated damage due to VIV can shorten the fatigue life of marine structures, so it needs to be considered in the design and operation phase. Semi-empirical VIV prediction tools are based on hydrodynamic coefficients. The hydrodynamic coefficients can either be calculated from experiments on flexible beams by using inverse analysis or theoretical methods, or obtained from forced motion experiments on a circular cylinder. Most of the forced motion experiments apply harmonic motions in either in-line (IL) or crossflow (CF) direction. Combined IL and CF forced motion experiments are also reported. However, measured motions from flexible pipe VIV tests contain higher order harmonic components, which have not yet been extensively studied. This paper presents results from conventional forced motion VIV experiments, but using measured motions taken from a flexible pipe undergoing VIV. The IL excitation coefficients were used by semi-empirical VIV prediction software vivana to perform combined IL and CF VIV calculation. The key IL results are compared with Norwegian Deepwater Programme (NDP) flexible pipe model test results. By using present IL excitation coefficients, the prediction of IL responses for combined IL and CF VIV responses is improved.
Fabrication and Characterization of Additive Manufactured Nickel-Based Oxide Dispersion Strengthened Coating Layer for High-Temperature Application
Authors: Min Zheng , Parbat Sarwesh Narayan , Yang Li , Kang Bruce , Chyu Minking K.
Published: November 2017

Increasing turbine inlet temperature is important for improving the efficiency of gas turbine engine. Elevated thermal load causes severe oxidation and corrosion for base alloy in turbine airfoils. To survive in this extreme high-temperature and harsh oxidation environment, both outside protection like thermal barrier coatings (TBC) and inside air cooling have been applied to turbine blades. Significantly more protection can be achieved if the cooling channels are embedded near surface, constructed partially by the coating system and partially by the superalloy substrate. However, neither the ceramic coating layer nor the metallic bond coating layer in current TBC system can provide structural support to such internal cooling channels. Development of structural bond coating layers consequently becomes one of the key technologies to achieve this goal. The present study proposed a method to fabricate structural coating layers on top of turbine blades with the aid of additive manufacturing (AM) and oxide dispersion strengthened (ODS) nickel-based alloy. ODS powder comprised of evenly distributed host composite particles (Ni, Al, Cr) with oxide coating layers (Y2O3) was subjected to a direct metal laser sintering (DMLS) process to fabricate a desirable structural coating layer above nickel-based superalloy substrates. Systematic experimental tests were carried out focusing on the interface adhesion, mechanical strength, microstructure, and surface finish of the ODS coating layer. Based on characterization results from indentation tests and microscopy observations, an optimal coating quality was obtained under ∼250 W laser power. The selected samples were then characterized under isothermal conditions of 1200 °C for 2000 h. Scanning electron microscope (SEM) observations and energy-dispersive X-ray spectroscopy (EDX) analysis were conducted in different stages of the oxidation process. Results indicated a formation of Al2O3 scale on top of the ODS coating layer at early stage, which showed long-term stability throughout the oxidation test. The formation of a stable alumina scale is acting as a protective layer to prevent oxygen penetrating the top surface. Spallation of part of nickel oxide and chromium oxide is observed but the thickness of oxide scale is almost no change. In addition, the observed adhesion between ODS coating layer and substrate was tight and stable throughout the entire oxidation test. The present study has provided strong proof that additive manufacturing has the capability to fabricate structural and protective coating layers for turbine airfoils.
Frictional Hysteresis Model for Stick–Slip Behavior of Magnetorheological Elastomer Under Various Magnetic Field Strengths
Authors: Lim Jinwoo , Lee Kwang-Hee , Lee Chul-Hee
Published: November 2017

In recent studies, many mathematical models have been introduced to describe the shear deformation characteristics of a magnetorheological elastomer (MRE). Owing to its beneficial elastomeric characteristics, an MRE can be adopted in novel controllable devices such as friction dampers and brakes. In this study, mathematical models are introduced to identify the frictional behavior of an MRE under different magnetic field conditions. Specifically, the improved LuGre (I-LuGre) model and the strain-stiffening model are compared using a system identification method. To identify the model that best describes the stick/slip behavior of an MRE, a harmonic frictional force was exerted on its surface with magnetic fields of varying strength. The I-LuGre model showed a precise correlation with the experimental results, and the strain-stiffening model was shown to have a simple structure for describing the frictional phenomenon. The system output error of the I-LuGre model remained within smaller errors than that of the strain-stiffening model. The parameter variations of each model that can be utilized to construct a control strategy are provided herein.
Effects of Compound Groove Texture on Noise of Journal Bearing
Authors: Meng F. M. , Zhang W.
Published: November 2017

The noise of a journal bearing with the compound groove textures is studied based on computation fluid dynamic (CFD) theory and broadband noise source theory. In doing so, the acoustic power levels of the noise for the journal bearing with the compound groove textures and simple ones are separately solved at different geometry sizes and positions of the groove texture, and varied lubricant parameters using CFD method. Numerical results show that the compound groove texture can more effectively lower the acoustic power level of the journal bearing, compared with the simple groove texture. This reduction depends on the groove size and its position, and density and viscosity of the lubricant.
Reciprocating Shaft Seals for High-Temperature and High-Pressure Applications: A Review
Authors: McKee Michael , Gordaninejad Faramarz
Published: November 2017

This study reviews the work performed in the field of reciprocating shaft seals from the advent of the scientific topic in the 1940s. Concepts of leakage, film layers, friction, wear, and other concerns with shaft seals are discussed. The importance of shaft seals as it pertains to liquid springs is brought to light along with issues requiring a need for these seals to withstand high temperatures and high pressures. Issues resulting from a seal exposure to high temperatures, such as thermosetting and embrittlement, are discussed in conjunction with materials and properties that allow seals to operate in high-temperature environments. High-pressure sealing challenges are identified along with the techniques currently employed to overcome these issues, such as fiber reinforcement and backup rings. Sealing solutions have been implemented independently for both high-pressure and high-temperature applications; however, the combination of high pressures coupled with high temperatures is still a challenge today.
A Study on the Influence of Micro Surface Texture on Mixed EHL Friction
Authors: Li Sheng , Parmar Utsav
Published: November 2017

In this work, the impact of the surface micro-dimple arrays on the frictional behavior under the mixed elastohydrodynamic lubrication condition is examined, considering a point contact problem. The interested geometric parameters of the micro-dimple arrays include the dimple center distance and the dimple depth. To quantify the influence of these parameters on the friction coefficient, a computational approach is implemented. In addition, different surface texture combinations, namely micro-dimpled and polished surface versus polished surface, polished surface versus polished surface and ground surface versus ground surface, are compared to determine any advantage or disadvantage of micro-dimpled surfaces on the aspect of the friction performance under the typical gearing application operating conditions.
A Method to Determine Grinding Wheel Profiles for Manufacturing Threads in Planetary Roller Screw Mechanism
Authors: Fu X. J. , Liu G. , Ma S. J. , Zhang W. J.
Published: November 2017

In this paper, a method to determine the axial profiles of the grinding wheels for machining the screw, roller and nut in planetary roller screw mechanism is proposed. Firstly, the thread fillets of the screw, roller and nut are defined and there is a continuous first-order derivative at any point of the fillets. The equations of thread surfaces are derived. Secondly, the position relationship between grinding wheel and workpiece is described by using a coordinate transformation matrix. Thirdly, according to the theory of gear engagement, the equations of meshing for the grinding of the screw, roller and nut threads are developed. A parameterized program is designed by the meshing equations and the axial profiles of the grinding wheels are calculated. Finally, a specific example is provided and the influence of center distance and axis angle on the grinding wheel profiles is analyzed. The results show that the center distance has little influence of the grinding wheel profile.
The Study of Parameters Matching Technology for Integrated Starter Generator
Authors: Zhou Yong , Han Yanting , Mi Yanzhao , Chen Long
Published: November 2017

Energy crisis and environment pollution are closely correlated with the widespread use of internal combustion engine (ICE) vehicles. Considering multi-factors, developing hybrid electric vehicle (HEV) is an ideal solution to solve the problems since its environmental protection and practicability. Integrated Starter Generator (ISG), integrated by two motors between engine and mechanical transmission system, performs better in efficiency and economy. This paper attempts to design a parameter matching method of hybrid electric system according to its dynamic performance, driving condition and control strategy. An ISG model and the model of parameter matching HEV system are proposed in this paper.
Feature Recognition and Parameterization Methods for Algorithm-Based Product Development Process
Authors: Weber Martins Thiago , Anderl Reiner
Published: November 2017

The algorithm-based product development process applies mathematical optimization tools in the conceptual steps of the product development process. It relies on formalized data such as initial loads and boundary conditions to find the best product solution for optimized bifurcated sheet metal parts. Previous research efforts focused on the automation of CAD modeling steps. Current algorithms are able to generate the CAD models of optimized bifurcated sheet metal products automatically, however, they are rough with low-level of detail and abstraction. Consequently, CAD models are embodied and detailed manually in a partly iterative and time-consuming process to include parameters, constraints and design features. Hence, this paper introduces feature recognition and parametrization methods for the algorithm-based product development of bifurcated sheet metal products. It proposes the inclusion of a pre-processor to analyze the solution graph resulted from topology optimization before the generation of CAD models. Algorithms that derive the geometric shape from the solution graph by recognizing features as well as assigning parameters are introduced. Then, feature-based CAD models of bifurcated sheet metal products are automatically generated. The proposed methods and algorithms are implemented with Python and validated with a use-case. Benefits and limitations of the proposed methods are discussed.
Effect of Track Geometric Irregularity on Dynamic Characteristics of Gear Transmission in a Locomotive
Authors: Zhang Tao , Chen Zaigang , Zhang Jie , Sui Shunqi , Pan Cheng
Published: November 2017

Gear transmission is a key component in locomotive where it delivers the traction or braking forces between the motor and the wheelset. Its working performance has a direct effect on the operating reliability and safety. Therefore, investigation on the dynamic characteristics of the gear transmission in locomotives is very meaningful. In this study, a gear transmission-locomotive-track spatial coupled dynamic model is established based on the classical locomotive-track coupled dynamics and the gear dynamics theory. Based on this model, the dynamic responses of the gear transmission can be analysed under excitations from different track geometrical irregularity, and the dynamic performance of the gear transmission can be obtained. This paper also studies the effect law of the track irregularity on the vibration of the gear transmission by using statistical indicators RMS (Root Mean Square) and PtP (Peak-to-Peak). The results indicate that the track geometrical irregularity has an obvious impact to the dynamic performance of gear transmission. The dynamic response of the gear transmission will increase violently when the locomotive runs on the track in a worse condition. The results are expected to be capable of providing some references for fatigue life prediction and reliability analysis of the gear transmissions in locomotive.
Investigation on the Lubrication Performances and Thermal Characteristics of the Tapered Roller Bearing
Authors: Zhang Yunjia , Ruan Dengfang
Published: November 2017

In this paper, the tapered roller bearing supported on the output shaft of the dual clutch transmission was studied. During the operating process of the DCT (Dual Clutch Transmission) gearbox, the heat generation of the bearing is very large due to the large operating load and high operating speed, which will easily result in bearing failure, such as pitting and abrasion, so it is necessary to investigate the lubrication performances and thermal characteristics of the tapered roller bearing. The simulation models considering or not considering the roller’s spinning (the rollers rotating on their own axles) were established based on Ansys Fluent software. The influences of the roller’s spinning on the lubrication performances of the bearing were analyzed. Furthermore, the transit heat transfer properties of the bearing were simulated and analyzed. The roller’s spinning and transit heat boundary specification were realized by using UDF (user-defined functions). At the same time, the lubrication performances and heat transfer properties of the bearing with different operating conditions are presented and analyzed.