bluuebunny/crossref_metadata_2025 huggingface dataset:
Person‐directed care planning in nursing homes: A scoping review
Authors: Lepore Michael , Scales Kezia , Anderson Ruth A. , Porter Kristie , Thach Trini , McConnell Eleanor , Corazzini Kirsten
Published: October 2018

Aim

Federal regulations require nursing homes in the United States to support residents in directing their own care rather than having their care plans developed for them without their engagement, but knowledge of person‐directed approaches to care planning in nursing homes is limited. The purpose of this study was to advance understanding of person‐directed care planning (PDCP).

Methods

A multidisciplinary research team conducted a scoping review on individual and family involvement in care planning, including literature from a variety of care contexts. Search results were systematically screened to identify literature that addressed individual or family involvement in care planning as a primary concern, and then analysed using thematic content analysis.

Results

Several themes were identified, including definitions of the concept of PDCP, essential elements of PDCP, barriers, facilitators and outcomes. The concept of PDCP is informed by multiple disciplines, including humanist philosophy, disability rights and end‐of‐life care. Essential elements of PDCP include knowing the person, integrating the person's goals in care planning and updating care plans as individuals’ needs or preferences change. Limited time for care planning in nursing homes hinders PDCP. Facilitators include regulatory mandates and humanist social trends. Outcomes of PDCP were found to be positive (e.g., increased independence), but were inconsistently assessed across studies.

Conclusion

This study offers pragmatic information that can support PDCP within nursing homes and insights for policy reform that may more effectively support PDCP.

Implications for practice

These findings can be used to guide implementation of PDCP.
Visual training in hemianopia alters neural activity in the absence of behavioural improvement: a pilot study
Authors: Larcombe Stephanie J , Kulyomina Yuliya , Antonova Nikoleta , Ajina Sara , Stagg Charlotte J , Clatworthy Philip L , Bridge Holly
Published: October 2018

Background

Damage to the primary visual cortex (V1) due to stroke often results in permanent loss of sight affecting one side of the visual field (homonymous hemianopia). Some rehabilitation approaches have shown improvement in visual performance in the blind region, but require a significant time investment.

Methods

Seven patients with cortical damage performed 400 trials of a motion direction discrimination task daily for 5 days. Three patients received anodal transcranial direct current stimulation (tDCS) during training, three received sham stimulation and one had no stimulation. Each patient had an assessment of visual performance and a functional magnetic resonance imaging (fMRI) scan before and after training to measure changes in visual performance and cortical activity.

Results

No patients showed improvement in visual function due to the training protocol, and application of tDCS had no effect on visual performance. However, following training, the neural response in motion area hMT+ to a moving stimulus was altered. When the stimulus was presented to the sighted hemifield, activity decreased in hMT+ of the damaged hemisphere. There was no change in hMT+ response when the stimulus was presented to the impaired hemifield. There was a decrease in activity in the inferior precuneus after training when the stimulus was presented to either the impaired or sighted hemifield. Preliminary analysis of tDCS data suggested that anodal tDCS interacted with the delivered training, modulating the neural response in hMT+ in the healthy side of the brain.

Conclusion

Training can affect the neural responses in hMT+ even in the absence of change in visual performance.
Cutting the Gordian Knot of abiotic stress in grapevine: From the test tube to climate change adaptation
Authors: Carvalho Luísa C. , Amâncio Sara
Published: October 2018

In Mediterranean climate areas, the available scenarios for climate change suggest an increase in the frequency of heat waves and severe drought in summer. Grapevine (Vitis vinifera L.) is a traditional Mediterranean species and is the most valuable fruit crop in the world. Currently, viticulture must adjust to impending climate changes that are already pushing vine‐growers toward the use of irrigation, with the concomitant losses in wine quality, and researchers to study tolerance to stress in existing genotypes. The viticulture and winemaking worlds are in demand to understand the physiological potential of the available genotypes to respond to climate changes. In this review, we will focus on the cross‐talk between common abiotic stresses that currently affect grapevine productivity and that are prone to affect it deeper in the future. We will discuss results obtained under three experimental stress conditions and that call for specific responses: (1) acclimatization of in vitro plantlets, (2) stress combinations in controlled conditions for research purposes, (3) extreme events in the field that, driven by climate changes, are pushing Mediterranean species to the limit. The different levels of tolerance to stress put in evidence by the plasticity of phenotypic and genotypic response mechanisms, will be addressed. This information is relevant to understand varietal adaptation to impending climate changes and to assist vine growers in choosing genotypes and viticulture practices.
Comprehensive transcriptome profiling and phenotyping of rootstock and scion in a tomato/potato heterografting system
Authors: Zhang Guanghai , Mao Zichao , Wang Qiong , Song Jie , Nie Xuheng , Wang Tingting , Zhang Han , Guo Huachun
Published: October 2018

Tomato/potato heterografting‐triggered phenotypic variations are well documented, yet the molecular mechanisms underlying grafting‐induced phenotypic processes remain unknown. To investigate the phenotypic and transcriptomic responses of grafting parents in heterografting in comparison with self‐grafting, tomato (Sl) was grafted onto potato rootstocks (St), and comparative phenotyping and transcriptome profiling were performed. Phenotypic analysis showed that Sl/St heterografting induced few phenotypic changes in the tomato scion. A total of 209 upregulated genes were identified in the tomato scion, some of which appear to be involved in starch and sucrose biosynthesis. Sl/St heterografting induced several modifications in the potato rootstocks (St‐R), stolon number, stolon length and tuber number decreased significantly, together with an increase in GA3content of stolon and tuber, compared with self‐grafted potato (St‐WT). These results indicate that the tomato scion is less effective at producing substances or signals to induce tuberization but promotes stolon development into aerial stems and sprouting. RNA‐Seq data analysis showed that 1529 genes were upregulated and 1329 downregulated between St‐WT and St‐R; some of these genes are involved in plant hormone signal transduction, with GID1‐like gibberellin receptor (StGID1) and DELLA protein (StDELLA) being upregulated. Several genes in auxin, abscisic acid and ethylene pathways were differentially expressed as well. Various hormone signals engage in crosstalk to regulate diverse phenotypic events after grafting. This work provides abundant transcriptome profile data and lays a foundation for further research on the molecular mechanisms underlying RNA‐based interactions between rootstocks and scions after tomato/potato heterografting.
Political Information Has Bright Colors: Narrative Attention Theory
Authors: Peterson Holly L.
Published: October 2018

Attention plays an important role in driving policy process dynamics at multiple levels of analysis. Despite this, narrative policy process studies often center on the position that narrative is strategically used in subsystem debates because it alters policy beliefs and preferences. This paper explicates the relationship between narrative and attention in the policy process according to theory and empirical findings in the Punctuated Equilibrium Theory (PET) and Narrative Policy Framework (NPF) literatures, developing a theory of narrative attention. According to Narrative Attention Theory (NAT), narrative focuses attention at multiple levels of analysis in the policy process, but is most important to consider at the macro level, where preferences are most stable. In associating PET's notion of macro political institutions (e.g., executive branch) and NPF's macro level of analysis (institutions or culture), NAT offers new hypotheses about narrative dynamics, a PET macro institutional approach to NPF's macro level, and an NPF conceptualization of PET's policy image.
Should heart rate variability be “corrected” for heart rate? Biological, quantitative, and interpretive considerations
Authors: de Geus Eco J. C. , Gianaros Peter J. , Brindle Ryan C. , Jennings J. Richard , Berntson Gary G.
Published: October 2018

Metrics of heart period variability are widely used in the behavioral and biomedical sciences, although somewhat confusingly labeled as heart rate variability (HRV). Despite their wide use, HRV metrics are usually analyzed and interpreted without reference to prevailing levels of cardiac chronotropic state (i.e., mean heart rate or mean heart period). This isolated treatment of HRV metrics is nontrivial. All HRV metrics routinely used in the literature exhibit a known and positive relationship with the mean duration of the interval between two beats (heart period): as the heart period increases, so does its variability. This raises the question of whether HRV metrics should be “corrected” for the mean heart period (or its inverse, the heart rate). Here, we outline biological, quantitative, and interpretive issues engendered by this question. We provide arguments that HRV is neither uniformly nor simply a surrogate for heart period. We also identify knowledge gaps that remain to be satisfactorily addressed with respect to assumptions underlying existing HRV correction approaches. In doing so, we aim to stimulate further progress toward the rigorous use and disciplined interpretation of HRV. We close with provisional guidance on HRV reporting that acknowledges the complex interplay between the mean and variability of the heart period.
Complementing open innovation in multi‐business firms: practices for promoting knowledge flows across internal units
Authors: Moellers Thomas , Visini Camillo , Haldimann Mirella
Published: October 2018

Over the past decades open innovation (OI) practices have gained prominence among both scholars and practitioners as a mean to accelerate time‐to‐market and reduce development costs of innovations. Thereby scholars have nearly exclusively focused on cross‐boundary knowledge flows between the focal firm and (its) external collaborators. This paper argues that such a focus limits our understanding of how multi‐business firms with a diverse knowledge base profit from internally applied open innovation practices that in turn provide complementary benefits to OI. We build on the current literature by investigating and describing OI activities that are conducted within the boundaries of the multi‐business firm. Based on a multiple case study of 23 collaboration practices conducted across 14 firms, our findings reveal 5 archetypal forms of internally applied open innovation activities. We draw on the literature of cross‐divisional innovation and crowdsourcing to highlight how these archetypes differ in terms of their purpose and underlying managerial processes. Multi‐business firms regularly rely on internal practices due to lower transaction costs and for stimulating a collaborative culture. We conclude that internally applied OI practices are effectively stimulated by a combination of non‐monetary reward systems and purposive integration mechanisms.
Whole genome sequence analysis to detect signatures of positive selection for high fecundity in sheep
Authors: Nosrati Maryam , Asadollahpour Nanaei Hojjat , Amiri Ghanatsaman Zeinab , Esmailizadeh Ali
Published: October 2018

Contents

Ovulation rate and prolificacy are the most important reproductive traits that have major impact on the efficiency of lamb meat production. Here, we compared the whole genomes of the Romanov sheep, known as one of the high prolific breeds, and four other sheep breeds namely Assaf, Awassi, Cambridge and British du cher, to identify genetic mechanisms underlying prolificacy in sheep. Selection signature analysis revealed 637 and 477 protein‐coding genes under positive selection from FST and nucleotide diversity (Pi) statistics, respectively. Further analysis showed that several candidate genes including LEPR, PDGFRL and KLF5 genes are involved in sheep prolificacy. The identified candidate genes in the selected regions are novel and provide new insights into the genetic mechanisms underlying prolificacy in sheep and can be useful in sheep breeding programmes to develop improved breeds for high reproductive efficiency.
Interfacial long traveling waves in a two‐layer fluid with variable depth
Authors: Pelinovsky Efim , Talipova Tatiana , Didenkulova Ira , Didenkulova (Shurgalina) Ekaterina
Published: October 2018

Long wave propagation in a two‐layer fluid with variable depth is studied for specific bottom configurations, which allow waves to propagate over large distances. Such configurations are found within the linear shallow‐water theory and determined by a family of solutions of the second‐order ordinary differential equation (ODE) with three arbitrary constants. These solutions can be used to approximate the true bottom bathymetry. All such solutions represent smooth bottom profiles between two different singular points. The first singular point corresponds to the point where the two‐layer flow transforms into a uniform one. In the vicinity of this point nonlinear shallow‐water theory is used and the wave breaking criterion, which corresponds to the gradient catastrophe is found. The second bifurcation point corresponds to an infinite increase in water depth, which contradicts the shallow‐water assumption. This point is eliminated by matching the “nonreflecting” bottom profile with a flat bottom. The wave transformation at the matching point is described by the second‐order Fredholm equation and its approximated solution is then obtained. The results extend the theory of internal waves in inhomogeneous stratified fluids actively developed by Prof. Roger Grimshaw, to the new solutions types.
Linguistic indirectness in parent–preschooler reminiscing about emotion‐related events: Links with emotion regulation and psychosocial adjustment
Authors: Hernandez Erika , Carmichael Katie , Kiliç Şükran , Dunsmore Julie C.
Published: October 2018

The concept of linguistic indirectness is well established within the field of pragmatics, in which it has been observed that speakers express ideas directly and indirectly. We integrated the analysis of linguistic directness and indirectness with the examination of two established measures of parental emotion socialization through reminiscing: elaboration and emotion explanations. We examined the unique associations of parents’ direct and indirect elaboration and emotion explanations with preschoolers’ emotion regulation and psychosocial adjustment. Participants were 55 parent–preschooler dyads (31 girls, 24 boys). The dyads reminisced about positive and negative events. Conversations were coded for parental elaboration, parental use of emotion explanations, and parental linguistic directness and indirectness. Children's emotion regulation was observed during standard tasks, and teachers reported on children's psychosocial adjustment. Multivariate regressions including direct elaboration and direct emotion explanations indicated that parents who engaged in more indirect elaboration when discussing positive events had children with worse emotion regulation. Parents who used indirect emotion explanations when discussing positive events had children with better psychosocial adjustment. Parents’ indirect speech during negative event discussions was not related to child outcomes. The results suggest differential functions for indirect elaboration and indirect emotion explanations in relation to children's social outcomes, and support the utility of examining linguistic indirectness.
Age‐related changes in lip morphological and physiological characteristics in Korean women
Authors: Kim Hyerim , Lee Myeongryeol , Park Sun Young , Kim Yong Min , Han Jiyeon , Kim Eunjoo
Published: October 2018

Objective

Age‐related changes in lip morphological and physiological characteristics are key indices for estimating age based on facial features, as reported in many studies. Yet, a majority of studies have focused on Caucasian individuals, with few studies characterizing these changes in Asian female populations. Therefore, the aim of this study was to investigate lip morphological and physiological characteristics in a cohort of Korean women.

Methods

A total of 114 volunteers participated in the study. Linear distances (length of philtrum, length of lip, width of lip, and lengths of lower and upper oral commissures), angle of the upper lip, 3D lip heights, and wrinkles were calculated and averaged for each age‐group. We also measured lip color, hydration, trans‐epidermal water loss (TEWL), and blood flow. Statistical analyses were performed using SPSS version 20.0 (significance level P < 0.05).

Results

Length of the philtrum and lip width significantly increased with age while upper and lower lip lengths and length of the lower oral commissure significantly decreased with age. The angle of the upper lip tended to decrease with age, but this finding was no significance. Three‐dimensional height of the upper lip, wrinkles, and TEWL also decreased with age while hydration increased with age. Finally, redness of the upper and lower lips as well as blood flow significantly decreased with age.

Conclusion

Lips tended to shorten in length and widen with age, resulting in a thinner and longer appearance. With regard to physiological parameters, there were important age‐related changes in hydration and lip color.
Impact of motion blur on stereo‐digital image correlation with the focus on a drone‐carried stereo rig
Authors: Balcaen R. , Lavatelli A. , Jiménez‐Peña C. , Pfeiffer H. , Zappa E. , Debruyne D.
Published: October 2018

Stereo‐digital image correlation (DIC) is a wide‐spread technique in the field of experimental mechanics for measuring shape, motion, and deformation and it is frequently used for material identification by using inverse methods (e.g., virtual fields method and finite element model updating). New applications emerge due to the reached maturity level of the technique, which poses new challenges towards reaching a desired level of accuracy in operating conditions. In this work, the possibility of a drone carrying an in‐house‐made portable DIC setup is explored, and the effect of the drone‐induced vibrations on the accuracy of stereo‐DIC for shape and strain measurement is evaluated. During acquisition, the relative motion between the camera system and the measured item generates motion‐blurred images. The effect of this phenomenon on the precision of stereo‐DIC is further evaluated in this paper.
Validation of an immunocytochemical assay for immunophenotyping of lymphoma in guinea pigs (Cavia porcellus)
Authors: Evans Samantha J. M. , Harr Kendal E. , Thielen Lauren , MacNeill Amy L.
Published: October 2018

Background

Lymphoma is an important disease of pet guinea pigs, although validation of immunophenotyping techniques based on cytologic or hematologic samples has not been reported.

Objective

To describe an immunocytochemical method for immunophenotyping of lymphoma (as either T‐ or B‐cell) in guinea pigs, and to validate antibodies for this purpose.

Methods

Blood and tissues were obtained at the time of necropsy from laboratory guinea pigs and a privately owned dog (control) euthanized for reasons unrelated to lymphoproliferative disease. Fine‐needle aspirates of enlarged peripheral lymph nodes were obtained from a case of spontaneous lymphoma in a pet guinea pig. Anti‐CD3 and anti‐Pax5 antibodies were validated by a combination of western blotting performed on splenic lysates of both the dog and guinea pigs, immunohistochemical studies on normal guinea pig tissues, and immunocytochemistry on normal guinea pig peripheral blood and splenic impression smears.

Results

The antibodies bound to antigens of an appropriate size in both the dog and guinea pig splenic lysates by Western blot analysis. Immunohistochemistry and immunocytochemistry demonstrated the expected distribution of putative T‐ and B‐lymphocytes in normal tissues, peripheral blood, and splenic impression smears. As a proof‐of‐principle for its clinical utility, this immunocytochemical assay was used to diagnose a B‐cell phenotype in a spontaneous lymphoma case in a pet guinea pig.

Conclusions

Here, we validated an immunocytochemical method for immunophenotyping of lymphoma in guinea pigs as either a T‐ or B‐cell phenotype. This enables future research into the clinical attributes of these subtypes and may ultimately improve both prognostication and therapy of lymphoma in guinea pigs.
When things go badly – Managing quality problems and complaints in transfusion medicine
Authors: Vuk Tomislav
Published: October 2018

Continuous and dynamic progress in all segments of transfusion medicine has significantly improved the quality, safety and efficacy of transfusion therapy. In addition to the scientific and technological innovations, implementation of the quality system and haemovigilance in blood establishments significantly contributed to this progress. Despite the fact that most of the activities in transfusion chain take place without problems, some risks are still present and even the best organized and managed systems are sometimes faced with quality problems and complaints. In transfusion medicine, their causes are mostly related to the biological origin of blood products, while the complexity of the process and a large number of participants in transfusion chain facilitates the occurrence of errors. Some quality problems are caused by materials and equipment used in product realization, inadequate education or skills of the staff, suboptimal planning and organization of work. The best approach to managing quality problems is preventative approach, including comprehensive risk management, education, defining critical control points, permanent quality monitoring and audits. Quality problems and complaints should be resolved in a timely manner, following the standardized protocol with clearly defined responsibilities. All procedures and decisions should be documented and traceable. The root cause analysis of the problem should be carried out and followed by appropriate corrective actions. The ultimate goal is to increase quality, safety, productivity, efficiency and customer satisfaction, while reducing defects and costs.
Sarcolemmal membrane excitability during repeated intermittent maximal voluntary contractions
Authors: Rodriguez‐Falces Javier , Place Nicolas
Published: October 2018

New Findings

What is the central question of this study?

Is impaired membrane excitability reflected by an increase or by a decrease in M‐wave amplitude?

What is the main finding and its importance?

The magnitude of the M‐wave first and second phases changed in completely different ways during intermittent maximal voluntary contractions, leading to the counterintuitive conclusion that it is an increase (and not a decrease) of the M‐wave first phase that reflects impaired membrane excitability.

The study was undertaken to investigate separately the changes in the first and second phases of the muscle compound action potential (M‐wave) during 4 min of intermittent maximal voluntary contractions (MVCs) of the quadriceps. M‐waves were evoked by supramaximal single electrical stimulation to the femoral nerve delivered in the resting periods between 48 successive MVCs of 3 s. The amplitude, duration and area of the M‐wave first and second phases were measured separately, together with muscle conduction velocity and MVC force. During the intermittent MVCs, the amplitude of the M‐wave first phase increased uninterruptedly for the first 3 min (12–16%, P < 0.05) and stabilized thereafter, whereas the second phase initially increased for 55–75 s (11–22%, P < 0.05), but decreased subsequently. The enlargement of the first phase occurred in parallel with an increase in its duration, and concomitantly with a decline in conduction velocity (maximal cross‐correlations, 0.89–0.97; time lag, 0 s). Also, a significant temporal association was found between the amplitude of the first phase and MVC force (time lag, 0 s; maximal cross‐correlations, 0.85–0.97). Conversely, there was no temporal association between the second phase amplitude and conduction velocity or MVC force (time lag, 73–117 s; maximal cross‐correlations, 0.65–0.77). It is concluded that the enlargement of the M‐wave first phase is the electrical manifestation of impaired muscle membrane excitability. The results highlight the importance of independently analysing the first and second phases, as only the first phase can be used reliably to detect changes in membrane excitability, while the second might be affected by muscle architecture.
Comparison of Grasping Performance of Tendon and Linkage Transmission Systems in an Electric-Powered Low-Cost Hand Prosthesis
Authors: Andrés F. Javier , Pérez-González Antonio , Rubert Carlos , Fuentes José , Sospedra Bruno
Published: October 2018

The popularization of fused deposition modeling (FDM) technology and open-source microcontrollers has permitted the explosion of electric hand prostheses that can be designed, shared, built, and operated at a low cost, under the Do It Yourself premise. Patients with limb reductions at the transcarpal or transradial level are best candidates to benefit from them. They manage the gross location with the remaining limb, while the built-in motors offer the possibility of controlling each finger independently. The number of mobile joints along the finger and the type of transmission can determine the quality of the grasp. Moreover, there is a need of objective procedures to assess the functionality of complete prototypes at reasonable effort. This work makes a critical review of the different transmission systems that can be found in most low-cost finger designs: linkage and tendon mechanisms. Mechanical performance has been analyzed using a standardized model of the index finger. Furthermore, robotic grasp quality metrics (GQM) have been used to evaluate by simulation the functionality of complete devices. Neither finger transmission design appeared clearly advantageous in the range of flexion studied. The evaluation of the complete devices gave slightly better quality grades for the linkage-driven model. Instead, tendon-driven model achieved a greater quantity of successful grasps. In the current state of art, some other aspects may have led to a dominant situation of the tendon-driven hands: fewer number of parts to be printed, easier assembly for a nonexpert user, advantageous in pursuit of lightweight devices.
Turbocharger Heat Transfer Determination With a Power-Based Phenomenological Approach and a Conjugate Heat Transfer Validation
Authors: Savic Bojan , Gao Xunan , Baar Roland
Published: October 2018

This investigation represents work on a model to determine heat flows on turbochargers. Recently, a power-based method has been developed to compare adiabatic and hot gas tests from radial turbines and compressors. Moreover, this method has shown the ability to correct standard measurements in terms of heat flows. In this investigation, a wastegate turbocharger has been investigated from a small gasoline engine. For validation purposes of the isentropic efficiencies, a conjugate-heat-transfer (CHT) simulation has been carried out on the turbine. Results have shown that isentropic efficiencies fit well for values of turbine inlet temperatures of 600 °C between corrected data and the simulation. For other temperatures, the differences between the determined values and CHT are greater. The differences rise with higher temperatures generally. So, the objective of the investigation is to improve the existing method for determining turbocharger heat transfers. Hence, an additional dependency of turbine inlet temperatures has been implemented in the approach and tested for T3 = 400 °C, 600 °C, 800 °C, and 950 °C. The modification has shown better results and smaller differences to CHT simulation. Especially, at low speeds where the former approach has had big differences, the modification improves the distribution for the investigated turbine inlet temperatures.
Experimental Evidence of Temperature Ratio Effect on Turbine Blade Tip Heat Transfer
Authors: Jiang H. , Zhang Q. , He L. , Lu S. , Wang L. , Teng J.
Published: October 2018

Determination of a scalable Nusselt number (based on “adiabatic heat transfer coefficient”) has been the primary objective of the most existing heat transfer experimental studies. Based on the assumption that the wall thermal boundary conditions do not affect the flow field, the thermal measurements were mostly carried out at near adiabatic condition without matching the engine realistic wall-to-gas temperature ratio (TR). Recent numerical studies raised a question on the validity of this conventional practice in some applications, especially for turbine blade. Due to the relatively low thermal inertia of the over-tip-leakage (OTL) flow within the thin clearance, the fluids' transport properties vary greatly with different wall thermal boundary conditions and the two-way coupling between OTL aerodynamics and heat transfer cannot be neglected. The issue could become more severe when the gas turbine manufacturers are making effort to achieve much tighter clearance. However, there has been no experimental evidence to back up these numerical findings. In this study, transient thermal measurements were conducted in a high-temperature linear cascade rig for a range of tip clearance ratio (G/S) (0.3%, 0.4%, 0.6%, and 1%). Surface temperature history was captured by infrared thermography at a range of wall-to-gas TRs. Heat transfer coefficient (HTC) distributions were obtained based on a conventional data processing technique. The profound influence of tip surface thermal boundary condition on heat transfer and OTL flow was revealed by the first-of-its-kind experimental data obtained in the present experimental study.
Numerical Investigation Into the Effects of Motion Parameters on Energy Extraction of the Parallel Foils
Authors: Wang Y. L. , Jiang W. , Xie Y. H.
Published: October 2018

Due to the deficiency of the research on parallel foils, the parallel configuration of foils is concerned and the effects of motion parameters on energy extraction are systematically discussed in the present study. The foils undergo combined plunging and pitching motions. The effects of motion parameters (pitching amplitude, plunging amplitude, reduced frequency, and spacing between foils) in wide range are investigated at Re = 1100 through two-dimensional (2D) unsteady laminar flow simulations. The features of power output and efficiency changing with these motion parameters as well as the evolution of the vortex fields are gained. The principle that how motion parameters affecting energy extraction performance is studied. The extraction performance of parallel foils and single foil is compared at the optimal working parameters of the single foil. Numerical results indicate the optimal extraction performance of the parallel foils is superior to that of the single foil. CPm improves by 6.87% relatively. Therefore, it reveals that the parallel foils can perform the better extraction characteristics than the single foil by controlling parameters.
Strakes Effects on Asymmetric Flow Over a Blunt-Nosed Slender Body at a High Angle of Attack
Authors: Yuan Qihang , Wang Yankui , Qi Zhongyang
Published: October 2018

In general speaking, the missiles execute flight at high angles of attack in order to enhance their maneuverability. However, the inevitable side-force, which is caused by the asymmetric flow over these kinds of traditional slender body configurations with blunt nose at a high attack angle, induces the yawing or rolling deviation and the missiles will lose their predicted trajectory consequently. This study examines and diminishes the side-force induced by the inevitable asymmetric flow around this traditional slender body configuration with blunt nose at a high angle of attack (AoA = 50 deg). On one hand, the flow over a fixed blunt-nosed slender body model with strakes mounted at an axial position of x/D = 1.6–2.7 is investigated experimentally at α = 50 deg (D is the diameter of the model). On the other hand, the wingspan of the strakes is varied to investigate its effect on the leeward flow over the model. The Reynolds number is set at ReD = 1.54 × 105 based on D and incoming upstream velocity. The results verify that the formation of asymmetric vortices is hindered by the existence of strakes, and the strake-induced vortices develop symmetrically and contribute to the reduction in side-force of the model. In addition, the increase in strake wingspan reduces asymmetric characteristics of the vortex around the model and causes a significant decrease in side-force in each section measured. The strake with the 0.1D wingspan can reduce the sectional side-force to 25% of that in the condition without strakes.
Numerical Investigations of Flow Past a Rotating Stepped Cylinder
Authors: Shin Jamie , Rahai Hamid , Taherian Shahab , Ferris Ryan J.
Published: October 2018

Unsteady numerical investigations of flow past a partially rotating stepped cylinder have been performed. The objective of the study was to investigate whether the wake characteristics could be controlled with rotation of one cylinder while the other remains stationary and how partial rotation impacts the aerodynamic forces. The stepped cylinder was 2 m in length where the first meter was a round cylinder 5 cm in diameter followed by a 2:1 step down cylinder. Two round end plates, 0.1 cm thick and 40 cm in diameter, were placed at each end. The end plates were positioned at 5 degrees with respectto the incoming flow to remove the end effect on vortex shedding. All simulations were performed using the Siemens PLM STAR-CCM+ CFD software with K-ω turbulence model. The time step was 0.00083 second to resolve the flow for each 10 degrees rotation. 1200 time steps were used. The investigations were performed with one cylinder rotating while the other remains stationary. Four cases were investigated. When either cylinder was rotating, the RPM was maintained at either 2000 or 4000 while the free stream velocity was maintained at 10 m/sec. The Reynolds number for the large and small cylinders were approximately 32,258 and 16,129, respectively. The corresponding velocity ratios λ for the large cylinder rotating were 0.5 and 1.0, and 0.25 and 1.0 for the small cylinder.

Previous investigations have classified vortical structure in the wake of a step cylinder in terms of L-cell (for large cylinder), S-cell (for small cylinder) and N-cell (the region in between). When the large cylinder is rotating, at λ = 1.0, the velocity and vorticity in the wake of the large cylinder is increased. The N-cell initially has a larger velocity than the L-cell and is at a slanted angle. A suction effect was observed in the near wake region, causing the flow in the L-cell to coalesce near its midsection. The vortices originated at the step were connected to the S-cell at a lower speed. The overall lift to drag ratio (L/D) for this case was 1.14. When λ = 0.5, vortex structures were maintained through the three different cells with increased variations in cell frequency across the large cylinder, the L/D was reduced to 0.36.

When the small cylinder was rotating, at λ = 0.5, vortex shedding was suppressed within the S-cell and considerable distortion was observed in the vortical structure in the wake of the large cylinder. However, the N-cell had similar structure as when large cylinder was rotating, but connecting to the L-cell at a larger slanted angle. When λ was reduced to 0.25, shedding was observed across the length of the cylinder with increased variations. The corresponding L/D ratios for these cases were both at 0.2.
Numerical and Experimental Study of Inner Flow and Hydraulic Performance of the Mixed-Flow Pump With Low Specific Speed
Authors: Yuan Jianping , Fan Meng , Li Yanjun , Fu Yanxia , Lu Rong
Published: October 2018

Mixed flow pumps are very suitable for market demand with the rapid development of urbanization, especially for low specific speed mixed flow pumps which has been widely used in various fields [1–3]. In this study, the calculations of the incompressible 3D internal flow of the mixed-flow pump with low specific speed was carried out by using CFD technique based on the N-S equation coupled with the standard k-ε turbulence model at different flow rates. The hydraulic performances of the mixed-flow pump as well as the inner flow were analyzed in comparison with the corresponding experimental data. Meanwhile, the static pressure and relative velocity distribution on blades were studied at low, design as well as large flow rates, respectively. Finally, it can obtain that the predicted pump performance curves based on numerical simulation have a good agreement with the experimental results, which verify the numerical method applied in this work accurate in a certain extent. Furthermore, the results also provide some references to hydraulic forces and pressure fluctuation analysis and the performance improvement for the mixed-flow pump design.
CFD and Experiment Investigation of the Mixing Characteristics of Non-Newtonian Fluids in a Stirred Vessel
Authors: Wang Peng , Reviol Thomas , Ren Haikun , Böhle Martin
Published: October 2018

The mixing performance of a novel design propeller fixed at a position with the angle of −10° combine the inference of the variety of rotation speed and rheology properties were investigated using an ultrasonic Doppler anemometer (UDA) and CFD simulation to investigate the flow patterns and the power consumption in a mixing vessel. The fluids of interest in this research are CMC fluids, which is a type of Walocel CRT 40,000PA powder was added into water to prepare the solutions with the mass concentration which performed shear thinning non-Newtonian fluid properties. As the viscosity of the non-Newtonian fluids varies from the shear rate, rather than a constant value. Therefore, a non-Newtonian power-law model has been selected to describe the properties of the non-Newtonian fluids, and combine with six turbulence models (the standard k-ω model, RNG k-ε, standard k-ε, Realizable k-ε, SST k-ω and Reynolds stress model (RSM))for mechanical agitation of non-Newtonian fluids. Through comparing experiment results, the SST k-ω and Reynolds stress model (RSM) are found more physical than other turbulence models at the design operating point. Furthermore, the CFD simulation results from Reynolds stress model (RSM) and the SST models were validated with the experimental results over the range of rotation speed (small, design, and large rotation speeds), and show that the simulated propeller torque and flow patterns agreed very well with experimental measurements. The velocity field distribution with different operating conditions within selected planes also have been compared with each other and found that for different rheology concentrations and operating conditions, the turbulence model should be properly chosen. The model for simulating non-Newtonian fluid in a stirred vessel in this study can lay a foundation for further optimum research.
Flow Structures and Vortex Dynamics in the Wake of Three Tandem Prisms
Authors: Zheng Qinmin , Alam Md. Mahbub
Published: October 2018

A study of the flow around three tandem square prisms may provide us a better understanding of complicated flow physics related to multiple closely spaced structures. In this paper, a numerical investigation on the flow around three tandem prisms at Reynolds number Re = 150 is conducted for L/W = 1.2 ∼ 10.0, where L is the prism center-to-center spacing and W is the prism width. Four distinct flow regimes and their ranges are identified, viz., single bluff-body flow (L/W < 3.0), alternating reattachment flow (3.0 < L/W < 4.3), synchronized coshedding flow (4.3 < L/W < 7.3) and desynchronized coshedding flow (7.3 < L/W ≤ 10.0). The synchronized coshedding flow can be further subdivided into two regimes: single St flow (4.3 < L/W < 5.1) and dual St flow (5.1 < L/W < 7.3). A secondary vortex street following the primary vortex street is observed for the dual St flow and the desynchronized coshedding flow. The detailed physics of the evolution of the primary vortex street to the secondary is imparted. The inherent frequency associated with the secondary vortex street is smaller than that with the primary. The evolution process of the primary vortex street to the secondary leads to a tertiary frequency. The DMD (dynamic mode decomposition) analysis for the first time is proposed as a useful and quantitative tool to identify the secondary vortex street and its onset position.
Stall Flutter Measurements on a Rectangular Wing
Authors: Gkiolas D. , Mouzakis F. , Mathioulakis D. S.
Published: October 2018

The continuous development of wind turbine technology gradually leads to larger, more flexible blades with increasing aspect ratios and high tip speeds, while in everyday operation or extreme cases the blades experience stalled flow conditions. These aforementioned facts create the need for further study and physical understanding of stall induced vibrations – stall flutter. In this context an aeroelastic setup was constructed at the NTUA subsonic wind tunnel with a rigid rectangular wing (500 mm × 1400 mm) of a NACA 64-418 airfoil supported by a spring system that enables pitching and plunging motions. The elastic axis of the wing is located 35% of the chord far from the leading edge while its center of mass at 46%. Increasing the free stream velocity (up to Re = 670 000) under various initial static angles of attack, the wing was set at fluid induced oscillations (pitching and plunging). The response of the wing under these conditions was recorded employing two accelerometers and two wire sensors for both the rotational and linear wing displacements. At the same time, in the middle of the wing span thirty (30) fast responsive pressure transducers measured the pressure distribution along the chord, while strain gauges attached to the wing rotating shaft measured the applied unsteady aerodynamic loading. Based on the above simultaneously measured quantities various aspects of the aeroelastic instability of the examined wing were revealed.
Sand Erosion Model Prediction, Selection and Comparison for Electrical Submersible Pump (ESP) Using CFD Method
Authors: Zhu Haiwen , Zhu Jianjun , Rutter Risa , Zhang Jiecheng , Zhang Hong-Quan
Published: October 2018

Electrical submersible pump (ESP) is one of the most widely used artificial lift methods in the petroleum industry. It is crucial to study the wear in ESP stages with sand production, which can severely reduce pump performance and life span. Usually, experiments and simulation studies were conducted for simple flow geometry such as direct impingement and pipe elbow. Various erosion equations and models were developed for different material and affecting factors. However, the predictions of these erosion models for complex flow geometry need to be evaluated in order to make a proper selection. This study will compare the wear patterns and erosion rates of six different erosion models in three ESPs by using commercial Computational Fluid Dynamics (CFD) software ANSYS Fluent. The results will offer engineers a brief guidance of erosion model selection for complicated flow domain.

In this paper, stages of three ESPs, DN1750, TE2700 and Flex31, are modeled. For each pump, the flow domain of two stages are selected and high-quality structured meshes, comprising around 1.2 to 1.8 million hexahedral grids per stage, are generated by ICEM or Turbogrid. Six erosion models, Ahlert (1994), Haugen (1995), Zhang (2007), Oka (2007), Mansouri (2014) and DNV (2015), are simulated under pump best efficiency point.

Among six selected erosion models, Ahlert (1994) gives a much higher wear rate than others, while DNV predicts lowest, Besides, the impact angle functions show that all models, except Haugen (1995), assume steel to be a ductile material. Furthermore, the erosion pattern, location, and distribution of all three pumps are different, which indicates different solid particle handling capabilities and failure reasons of radial type and mixed type ESPs.
Three-Dimensional Volume of Fluid Simulations of Air Bubble Dynamics in a Converging Nozzle
Authors: Law Deify , Shepard Thomas G.
Published: October 2018

The present work relates to the dynamics of single bubbles accelerating through a converging nozzle. There are two main aspects to this study. First, this expands upon a previously used two-dimensional model [1] by providing three-dimensional volume of fluid (VOF) simulations that show better agreement with experiments. The VOF model is employed to perform simulations using the commercial computational fluid dynamics (CFD) code ANSYS FLUENT. Second, the present work uses experimental high-speed camera results in conjunction with simulation results to demonstrate bubble time trace and velocity information. Time series of the average liquid velocity at the atomizer exit orifice when the bubble exits as determined via simulation are reported. The passing of a bubble through the nozzle is found to cause a significant fluctuation in the exit velocity that is coupled to the liquid and gas dynamics upstream of the exit.
Lift and Drag Forces With Respect to Azimuth Position of a Darrieus Wind Turbine
Authors: Ali Sajid , Lee Sang-Moon , Jang Choon-Man
Published: October 2018

Tangential force is the most important parameter for driving the blade of a straight bladed H-Darrieus wind turbine forward. The direction of this force is very critical as it may move the blade forward (positive force) or it can also oppose the rotation (negative force). The direction of tangential force depends upon the distribution of two fundamental aerodynamic forces around the wind turbine blade i.e. Lift and drag. Current study aims to understand the impact of lift and drag forces on the tangential force variation with respect to (w.r.t) azimuth position. Commercial CFD software SC/tetra was employed in order to solve the unsteady Reynold-averaged Navier stokes (URANS) equations around the blades. Results show that very small portion (maximum 20% during rotation) of the drag force is actually converted into useful tangential force whereas rest of the drag force is converted into either normal force or negative tangential force (waste of energy). On the other hand, out of all the generated lift force, 70–90 percent is seemed to be beneficial for moving the blade forward and rest of the lift force also tries to oppose the motion (almost 15%). Overall, it was found that only 50–60 percent of the resultant force (lift + drag) acting on the blade, is actually useful to move the blade forward. The study was conducted at seven different tip speed ratios (TSRs) i.e. 1, 2, 2.28, 3, 3.5, 4 and 5 with NACA 0015 airfoil. Relatively higher fluctuations were observed in the distribution of forces at low values of TSRs (1 and 2) as compared to high values of TSRs (4 and 5). The results presented here are only limited to NACA 0015 whereas same methodology can be adopted for other blade profiles in future as well.